Qatar Foundation Annual Research Conference Proceedings Volume 2016 Issue 1
- تاريخ المؤتمر: 22-23 Mar 2016
- الموقع: Qatar National Convention Center (QNCC), Doha, Qatar
- رقم المجلد: 2016
- المنشور: ٢١ مارس ٢٠١٦
201 - 220 of 656 نتائج
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Application of TiO2–WO3 Composite for Continuous Reduction of Chromium(VI) in Light-limited Condition
المؤلفون: Rand Elshorafa, Dong Suk Han, Hyunwoong Park and Ahmed Abdel-WahabHexavalent chromium (Cr(VI)) is toxic and hazard chemical to human health and it is categorized as a carcinogen chemical. Cr(VI) is released from many industrial processes such as electroplating, metal finishing, and textile/leather dyeing. Although there are many treatment technologies for removal of Cr(VI), the photocatalytic treatment using metal oxide semiconductor (SC) materials has been shown to be a promising technology because of the fact that toxic Cr(VI) can be effectively reduced to less toxic Cr(III) by cheap, nontoxic, and stable photocatalyst such as titanium dioxide (TiO2). In this study, two different types of TiO2 particles (nano-sized particle, nanotube particle) were used as photocatalysts for Cr(VI) reduction. These two types have different kinetics of transferring the charge carriers. Based on results of this research, each TiO2 particle type was used for fabrication of multijuntion SC with WO3 particles for continuous reduction of Cr(VI) in water.
For the continuous reduction of Cr(VI), two different methods were applied: Photoelectrochemical(PEC) system and Nanofiltration system. Regardless of the method, WO3 was in junction with TiO2 in order to reduce Cr(VI) even in the dark because WO3 has an ability to storing solar energy through charging/discharging route. Upon light-on, the electrons that was photogenerated from TiO2 transfer to WO3, forming HxW(6-x)O3 of the photocharged surface specie. Upon light-off, the trapped electrons in WO3 are released gradually to the environment that requires electrons for certain chemical reactions to take place thermodynamically. The fabricated heterojunction TiO2/WO3 will have a good example of the photoelectrode to perform the multi-functionalities: solar light conversion and simultaneous solar energy storage, and electron transfer for application of environmental remediation.
In case of the PEC system, TiO2 was doped with WO3 on the fluorine doped tin oxide (FTO) glass by a layer-by-layer deposition technique. The TiO2/WO3 composites that was charged at AM 1.5 G irradiation (100 mW/cm2) shows a gradual reduction of Cr(VI) in the dark until 12 hours. Also, the Cr(VI) results were dependent on TiO2 type, doping ratio of TiO2 and WO3, and charging time.
For the nanofiltration system, the suspended TiO2/WO3 particles were filtered by anodic membrane filtration (20 nm of pore size) and subsequently the deposited TiO2/WO3 particles were charged by illumination of sunlight with light intensity higher than 200 mW/cm2. The charged TiO2/WO3 retained on the membrane was inserted to dead-end filtration apparatus and the membrane system was used for continuous reduction of Cr(VI) over filtration time. For this, various experimental conditions were applied, including loading amount of TiO2/WO3 with different ratio of TiO2/WO3, initial concentration of Cr(VI), charging time, reduction capacity over number of recycle of charging/discharging, etc. This system will have a benefit of no application of UV or light source in the filtration system, which is a major challenge when photocatalysis and filtration are combined for a specific treatment process. Therefore, we believe that two approaches will provide scientific and technical information for continuous removal of Cr(VI) in the light-limited condition.
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Role of Biodiesel in the Enhancement of GTL Diesel Fuel Properties
المؤلفون: Nimir Elbashir, Wajdi Jamal Ahmed, Ahmad Alrachid, Nasr Mohammed and Marwan ElwahshThe Conversion of natural gas into synthetic liquid fuel carried out through a catalytic conversion process, known as the gas-to-liquid (GTL) technology, had a great impact since its discovery. The process utilizes the Fischer-Tropsch synthesis (FTS) chemistry that was first developed in 1925. Gas-to-liquid (GTL) fuels are synthetic fuels that are intrinsically cleaner than conventional fuels.[1] They are environmentally benign due to the absence of sulfur content and the extremely low aromatic content. Gas-to-liquid (GTL) diesel fuel, being one of the most important GTL products, is therefore classified as ultra-clean fuel with lower emissions of carbon monoxide and particulates upon combustion. Nevertheless, the lack of sulfur and aromatic in the diesel fuels negatively impacts certain important physical characteristics such as lubricity and density. This fact makes these fuels improper for use in existing diesel engines. The lubricity issue is significant for GTL diesel fuels, as it not match the standards required by regulations in the United States, Europe and elsewhere. Lubricity is defined as “a qualitative term describing the ability of a fluid to affect friction between, and wear to, surfaces in relative motion under load.” [2]
The aim of this research project is to design new generation ultra clean diesel fuels, from the GTL process, that are environmentally friendly, have less emissions upon combustion but also practicable and compliant with global standards. The focus of this study is to develop a comprehensive knowledge and data to observe the possibility of stretching and tailoring the GTL diesel properties such that they meet the standards needed to be used in existing engines. The enhancement of lubricity, which serves as the major disadvantage, is to be carried out while maintaining all other physical properties within the range needed for existing engines and ASTM D975 and D7467 standards.
Fatty acid methyl and ethyl esters are biodiesels that can provide significant improvements in the lubricity of diesel fuel. Previous studies on the effects of fatty acid methyl esters on diesel fuel lubricity have shown an increase in lubricity associated with the addition of these esters [3]. Addition of these esters in GTL diesel was found to be the best fit for lubricity enhancement. Our campaign, unlike other studies on diesel lubricity, does not only focus on certain physical properties of diesel but provide a comprehensive study showing all changes in other properties that accompany the change of the targeted property, being diesel in this case.
For this study, four lubricity enhancement additives were selected. The selection covers a wide range of biodiesel characteristics and would thus allow deeper understanding of other factors such as saturation and chain length of esters on diesel lubricity and properties enhancement. The four esters that proved to have significant impact are Methyl Oleate (C19H36O2), Methyl Stearate (C19H38O2), Ethyl Oleate (C20H38O2) and Ethyl Stearate (C20H40O2). Both methyl and ethyl esters were found to affect the lubricity. However, other studies showed variation on which serves as a better lubricity enhancement additive. Our research will validate these findings and widen the study to experiment the effect of mixing different additives on all other diesel fuel properties. The concentrations of additives were selected to be in the range of 5%–20% by volume. For this purpose 28 blends were prepared for conducting the research.
Subsequently blends were tested for fuel characteristics and physical properties. The tests nclude vapor pressure, viscosity, flash point, pour point, cloud point, distillation performance, heat content and lubricity. Current results show an increase in density, viscosity, flash point and vapor pressure with increasing additive concentrations of biodiesel. In contrast, the increase in additive concentration decreased the pour point, cloud point, recovery by distillation and calculated cetane number. All the changes lie well within American Society of Testing and Materials (ASTM) standards.
The work will be further continued to validate experimental results with industry partners, testing of lubricity characteristics using advanced microscopy and conducting a thorough result analysis and representation statistical methods and visualization techniques.
This work will suggest ideal mixtures of GTL diesel and biodiesel additives that will best enhance the GTL diesel fuel. Such findings can be used in blending commercial GTL diesel fuel with suggested biodiesel to produce practicable, engine compliant and ASTM standard compliant GTL diesel. Since Qatar has the largest GTL plant in the world, this research is essentially significant and relevant. It also enriches Qatar's scientific research culture and serves the world by creating cleaner fuels for a cleaner environment.
References
[1] Elmalik, E.E., Raza, B., Warrag, S., Ramadhan, H., Alborzi, E., Elbashir, N.O. (2014). Role of Hydrocarbon Building Blocks on Gas-to-Liquid Derived Synthetic Jet Fuel Characteristics. Industrial & Engineering Chemistry Research, 53, 1856–1865.
[2] Crown, L., Warfield, L., Hockert, C. (2013). Handbook 130 (2013)- Uniform Laws and Regulations in the areas of legal metrology and engine fuel quality.
[3] Geller, D. P., & Goodrum, J. W. (2004). Effects of specific fatty acid methyl esters on diesel fuel lubricity. Fuel, 83(17-18), 2351–2356.
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Flooding Limitations in a Three-Phase Direct Contact Condenser for the Utilisation of Low-Grade Energy Sources for Desalination and Power Generation Application
مزيد أقلThe continuing enhancement of energy recovery cycles that exploit low grade energy resources requires an efficient heat absorption and rejection system. Implementation of a conventional surface type heat exchanger, evaporator or condenser has many disadvantages. The low efficiency, fouling, corrosion problems, high cost and high heat transfer resistance are the most important shortcomings that emerge as a result of the metallic barriers involved. On the other hand, a direct contact heat transfer device offers a high heat transfer area and reduces or eliminates fouling and corrosion problems. They can also work with very low temperature differences and subsequently can enhance the cycle efficiency. Direct contact heat exchangers clearly have many advantages over surface type heat exchangers and can also be efficiently used in places where the surface heat exchanger cannot be.
Accordingly, direct contact heat exchanger can be found in different applications, such as water desalination and power generation from geothermal brine. Water desalination utilising direct contact heat exchangers can be achieved by two general methods: direct contact freezing-melting and direct contact evaporation- condensation. The former is based on the ability to remove water from a solution by freezing it out as crystalline ice. The ice or crystal should contain only pure water; therefore the partial freezing separates the fresh water from brine. The ice melts at another stage to produce distilled water. Direct contact freezing exploits the concept of direct contact evaporation of a low boiling point working fluid by absorbing heat from surrounding continuous fluid (water). The heat absorbed by the working fluid; which causes the water to freeze, is equivalent to the energy required to melt the ice. The working fluid used must have a low boiling point and a high freezing point along with other properties mentioned above. Refrigerants such as carbon dioxide and butane are widely used as a working fluid. For second application, the most common application of direct contact heat exchangers is in the generation of electricity from hot geothermal brine, utilising low boiling point fluids and the conventional Rankine cycle. The first plant utilising a spray column, which produces 500 k. We was designed by Barber-Nichols Engineering and installed at the East Mesa Geothermal Field in the U.S. in 1980. The spray column was 12 m in length and 1 m diameter. Hot brine is flashed to remove the non-condensable gases before entering the spray column from the top, while the isopentane liquid is injected in to the bottom of the column through a suitable distributer. Direct contact counter-current heat transfer between the two fluids takes place throughout the column height. According to the density difference, isopentane drops/bubbles rise upward with brine falling down and exiting the column at the bottom after being cooled down. On the other hand, isopentane heats up as a result of absorbing heat from the brine, and leaves the column as a superheated vapour from the top of the column. Isopentane vapour expands through a turbine to produce electricity, is liquefied in a condenser, and sent back to the direct contact heat exchanger again.
For a bubble type three-phase direct contact condenser, it is widely reported that its performance is characterised by a volumetric heat transfer coefficient, which is directly proportional to the holdup ratio in the column. It is both economical and practical for the bubble type direct contact condenser to operate at the maximum possible holdup ratio. This, of course, increases the possibility of flooding, which considerably impairs the performance of the column. Flooding can be either defined as the case when the continuous phase is completely held up by the dispersed phase or the dispersed phase is swept backward by the continuous phase.
Two mechanisms could lead to the inception of flooding in the three direct contact columns, depending on the critical velocity of each individual phase. The critical velocity can be defined as a maximum velocity that can be achieved by a given direct contact system and it is a function of the bubble size, the flow rate and the physical properties of the phases. The first mechanism depends on the reduction in the dispersed phase (bubbles) upward velocity due to the interactions within a swarm of two-phase bubbles. The two-phase bubbles move closer together when the dispersed phase flow rate increases, which results in a further dispersed phase slowing. Bubbles are swept down and drain out with the continuous phase from the bottom of the column. Therefore, the danger from this form of flooding form is the increased loss of the working fluid. The second scenario assumes that the continuous phase is swept upwards because of a high dispersed phase flow rate. This occurs when the dispersed phase velocity passes the critical velocity. The result of this flooding type lies in a change of geometry and makes the heat transfer relationships available invalid. Accordingly, flooding can be defined as the case when the continuous phase is completely held up by the dispersed phase or the dispersed phase is swept backward by the continuous phase.
As the first time, experiments to study the limitation of flooding inception of three-phase direct contact condenser have been carried out in a counter-current small diameter vertical condenser. The total column height was 70 cm and 4 cm diameter. Only 48 cm has been used as an active three-phase direct contact condenser height. Vapour pentane with three different initial temperatures (40°, 43.5° and 47.5°) and water with a constant temperature (19°) have been used as a dispersed phase and a continuous phase respectively. Five different continuous phase mass flow rate and four different dispersed phase mass flow rate have been tested throughout the experiments.
The experimental results showed that the effect of dispersed phase initial temperature on flooding inception to be insignificant at low continuous phase velocity (v_L^(*1/2).
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Genome Mining of Secreted Effectors of Fusarium Oxysporum, Fusarium Solani and Rhizectonia Solani
المؤلفون: Resna Nishad and Talaat AhmedAbstract Introduction: Of the various devastating diseases triggered by necrotrophic fungi, the diseases caused by following fungi Fusarium oxysporum, Fusarium solani and Rhizectonia solani are of particular economic significance in date palm (Phoenix dactylifera L.) growing countries. Undoubtedly date palm is the most important fruit tree cultivated in Arabian Peninsula. Unfortunately date palm cultivation encounter many challenges, such as fungal diseases. It has been reported that Fusarium oxysporum, Fusarium solani and Rhizectonia solani are the major causative of various diseases in Date palm.
For successful colonization of host, necrotrophic pathogens secrete an arsenal of effector proteins that facilitates infection by manipulating host cell structure and function. Thus secretory proteins (SPs) are critical for both short and long range intercellular signaling during infection and colonization.
The present study is conducted on three date palm pathogens, which causing diseases like bayoud disease and other necrotrophic diseases including root rot. This study focused on molecular genetics of necrotrophic pathogenicity in date palm by following an in silico approach to mine putative secreted elicitors from publically available Fusarium oxysporum, Fusarium solani and Rhizectonia solani ESTs. Methodology: Methodology involved mining of 25213 Fusarium oxysporum ESTs, 12433, Fusarium solani ESTs and 22324 Rhizectonia solani ESTs for protein sequence based features characteristic of SPs (signal peptides). All the ESTs were collected from NCBI. With using ORF predictor (http://proteomics.ysu.edu/tools/OrfPredictor.html) algorithm, found out all the six frame ORF. Predisi (http://www.predisi.de/) and SignalP (http://www.cbs.dtu.dk/services/SignalP/) algorithms was exploited to infer signal peptide within the ORF. Followed by scanning of transmembrane domain performed with TMHMM (http://www.cbs.dtu.dk/services/TMHMM/) to discard the transmembrane sequences. 0 TM/1TM proteins were selected for further CD (conserved domain) search.
Before going to the mining experiment, the pathogenicity of soil isolated (from northern part of Qatar) fungal pathogen on Date palm was confirmed with detached leaf inoculation method. All the three fungi, Fusarium oxysporum, Fusarium solani and Rhizectonia solani showed necrosis in date palm leaf after three days of infection. Result and conclusion: Out of 25213 Fusarium oxysporum ESTs 24890 have ORF. 12176 ORF found in Fusarium solani ESTs. Above 60% of all the three fungal ESTs had signal peptide. Number of sequences narrowed down by transmembrane topology search and the sequence doesn't containing transmembrane domain were selected for conserved domain identification.
Subsequent to our searches with sequences lacking transmembrane domains, we could catalog candidate effector sequences based on conserved features common to characterized fungal effectors. In Fusarium oxysporum following protein found to be extracellular secretory protein, this include cellulose binding protein, which possibly involved in in host cell adhesion, qaq like polyprotein: a virulent associated protein, lysin motif: an effector protein, extracellular peptidase, cell wall hydrolase, 150 amino acid cerato platanin sequence (elicitor), alpha amylase, beta 1,3 glucanase and 165 amino acid necrosis inducing protein. These effector proteins have the ability to degrade plant derived compound, this suggest the role of the effectors in pathogenicity.
In addition to these high amount of lipid targeting enzymes and glycoside hydrolase found in all the three phyto pathogenic ESTs. Presents of secretory protease detected in Fusarium solani. Peptidase like superfamily domain found in Rhizectonia solani.
To date, none of these effectors have been cloned and thus we propose that the catalogued effectors will in future be useful for isolation and characterization of these identified proteins. Expression studies are already underway and we expect that the results will provide insights into mechanisms underlying host-Pythium interactions and thereby help in generating new strategies for effective date palm disease control.
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33-Level Single-Phase SubMultilevel Inverter for Grid-Connected Photo-Voltaic Systems Using Model Predictive Control
المؤلفون: Morcos Morad Saad Metry, Sertac Bayhan and Robert BalogGreen House Gases (GHG) that are currently being emitted from conventional energy production methods are of global concern; especially with the climate change that is occurring. The United Nations has taken the initiative by holding a global conference that aims combating climate change “United Nations Framework Convention on Climate Change (UNFCCC)”, which sets a common ground of regulations and agreements that aim at reducing polluting production methods. Qatar, as part of the UNFCCC, has signed and agreed to the Kyoto protocol. The first component of the protocol determines that countries should enhance energy efficiency in different sectors of their national economy.
In addition, “Qatar National Vision 2030”, states: “The rights of future generations would be threatened if the depletion of non-renewable resources were not compensated by the creation of new sources of renewable wealth”. With the increase in numbers of large-scale educational, industrial, commercial and residential buildings, Qatar needs to look into means of making them more energy efficient. Adopting solar energy is a priority for Qatar because of high abundance.
Photovoltaic (PV) systems transform sunlight into useful electricity with efficiencies that range from 12 to 20% without concentrators. PVs are designed with two layers, the n-layer (negative) and the p-layer (positive), which get charged when exposed to sunlight causing potential difference across the cell. PVs are static devices, eco-friendly, noise-less and require minimal maintenance. According to a study that compares unit generation costs of gas turbines and PVs, PVs are becoming a more viable alternative despite of the fact that they are still more expensive due to their initial installation costs. Another major disadvantage is the lower conversion efficiency. Power conditioning is also required in a solar PV system to convert DC power to AC power, regulate the load flow, offer different types of protection and keep the total harmonic distortion (THD) within the specified limit. Different types of inverters (DC to AC converter) have been employed for solar PV systems.
Dynamic behavior of solar energy resource entails the need of robust controllers that can converge to the maximum power point (MPP) to maximize energy harvest. The low conversion efficiency of PV systems is a significant hindrance to their growth, therefore Maximum Power Point Tracking (MPPT) is required to ensure the maximum available solar energy is harnessed from the solar panel. It is common in the industry that power conditioning is done at the array level. Less common but proven more efficient is to do conditioning at the module level. This guarantees maximum power is harnessed from one module regardless of the irradiance condition of the other neighboring modules. It would even be more efficient to do power conditioning at the cell level. In which case, each array of cells within a single module, has its own MPPT controller.
This project explores an improved Perturb and Observe (P&O) technique that combines a fixed step model predictive controller (MPC), to speed up the control loop, applied to a boost converter. The proposed MPC Maximum Power Point Tracking (MPPT) technique had proven higher efficacy and robustness over conventional MPPT. The main characteristic of MPC is predicting the future behavior of the desired control variables until a predefined step ahead in horizon of time. The predicted variables will be used to obtain the optimal switching state by minimizing a cost function.
A boost converter is used as a DC/DC converter prior to the sub multi-level inverter. P&O determines the reference current for the MPC, which determines the next switching state. This technique predicts the error of the next sampling time and based on optimization of the cost function g, the switching state will be determined. The inputs to the predictive controller are the PV system current and voltage, and the reference current. By deriving the discrete time set of equations, the behavior of control variables can be predicted at next sampling time k+1. The proposed methodology is based on the fact that the slope of the PV array power curve is zero at the predicted MPP, positive on the left and negative on the right of the predicted MPP.
The improved MPC-MPPT is tested for the first time on an MPC strategy of 33-level SubMultilevel Inverter (SMI) using 16 power arms cascaded with the H-bridge inverter. SMIs use less switches than conventional MIs and this is noticeable at larger number of levels. Such topology uses a switching frequency for the H-bridge that is equal to the grid frequency, which allows for lower switching losses when compared to conventional MIs. Such topology brings about many sizable benefits such as reduced number of power switches and their grate drivers when compared to the traditional multilevel inverter. MPC is also used as the control strategy for the SMI to eliminate complexities in the space vector pulse width modulation (SVPWM) and overcome the weaknesses of the inner control loop performance. This topology allows for each module to be divided into 16 parts each comprised of an array of cells. Each array of cells is connected to the MPC-MPPT boost converter. Then the 16 levels are fed to the input stage of the SMI. Finally, each module will have its own H-Bridge inverter that directly feeds the grid. Such topology provides the advantage of localized MPPT tracking, increased reliability of the whole power system as the failure of one cell won't fail the whole system, and lower components withstand ratings.
To verify the dynamic and steady-state performances of the proposed MPC scheme under various load and reference currents, simulation studies are performed with Matlab & Simulink software.
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Simulation Studies of Charged Particle Detectors for Collider Experiments
المؤلفون: Taif Mohamed and Neeraja RenganathanThe Compact Muon Solenoid (CMS) experiment in the Large Hadron Collider (LHC) at CERN has been the tool to performing ground-breaking research in high energy physics. The CMS detector has been built over the last two decades by an international collaboration of scientists from all over the world. Two years after its operation, the two experiments ATLAS and CMS have announced in 2012 the discovery of the Higgs boson, a long awaited particle responsible to give elementary particles their respective masses.
After the first 3 years of operation at moderate luminosity, the LHC is entering a new phase of high luminosity and energy regimes, which will put stringent requirements on the detectors.
The CMS experiment has planned a rigorous plan of upgrade of its different components to cope with the harsh conditions imposed by the new regime. One of the subsystem of CMS detector that will require upgrade is the muon system. This latter detects muon particles, which are the signature of most of the interesting physics channels we are looking for at the LHC.
The Qatar team, together with an international team of scientists, has proposed the Gas Electron Multiplier (GEM) as the future detecting element of the upgrade of the muon system.
We have conducted an extensive simulation program to assess the GEM detector and optimize it for the future upgrade.
During this project, various simulations have been conducted to predict the efficiency and time resolution of the GEM. The simulations, which have been conducted using ANSYS, computational fluid dynamics software, focus on producing the electric field maps inside the detector. In addition, the resulting electron avalanche was simulated based on the solution of the Boltzmann equation. A signal was then generated to study the gain, resolution, and other parameters. During this work, several conditions were simulated in order to reach the optimum conditions under which the GEM would be most effective. These simulations had to be conducted using a supercomputing facility since their range surpasses the regular computing powers of personal computers. Using Raad, the cluster at Texas A&M University at Qatar, helped widen the scope of the simulations to approach a realistic situation that would occur within the CMS.
Furthermore, as part of its next upgrade, a novel detector, the Fast Timing Micropattern (FTM) detector is being considered as a possible beneficial addition to the CMS. Initial investigations of the FTM detector have shown a considerable improvement in the time resolution that is proportional to the number of layers. In addition, the use of resistive WELL techniques solves the problem of spark occurrences and discharges that such detectors experience with high electric fields. It also differs from the GEM in the sense that the gain is extracted at every multiplication stage rather than at the very last level of the detector where the readout plane exists. The FTM detector could be cost-efficient in its assembly process. Simulations are being further extended in order to evaluate the FTM's performance and optimize its gain and other resulting parameters.
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Green Mobility Application (GMAP)
المؤلفون: Nurettin Sezer, Irfan Batur and Ibrahim ArıBroadly speaking, one of the most important aspects of Sustainable Development Goals (SDGs) of United Nations is to increase awareness of people for sustainability related issues namely economic, environmental and social problems. In this direction, it can be concluded that there is a lack of awareness for individuals regarding their habits and their related impacts on sustainability. Especially in developed countries, it is well-known that people are linked to over consumption, overweight, over waste, over pollution and so on. However, most of them are not aware of the results which are caused from their daily activities in terms of pollution, waste, energy footprints and their related effects on global sustainability. Mobility is one such area resulting in that kind of problems especially in urban areas. Our current road-based transportation system which is mainly dependent on automobile use causes a wide range of formidable problems. These include traffic congestion, air pollution, noise, accidents and related fatalities, depletion of non-renewable resources and inaccessibility of amenities and services. To illustrate this, more than one-quarter of total U.S. greenhouse gas emissions come from the transportation sector and light vehicles are responsible for 59% of transportation energy use (see Fig. 1). Due to the accidents on roads, approximately one million people dies except the millions of injuries (WHO, 2010). In addition to that, there are many cities suffering from traffic congestion which slows down daily businesses, causes unreliability in terms of time, results in unpleasant life in urban life and costs billions of dollars to the economies (Everyday Money, 2014; TomTom, 2013). These are just few figures to illustrate detrimental effects of transportation especially due to automobile use in urban areas. Transport demand, however, increases as economic growth increases (EU Energy, 2012) which will make the situation even worse in the upcoming years. Therefore, there are various dimensions of transport system which can be group into three categories: economic, environmental, and social (see Table 1). Given these problems, and their associated economic, environmental, and social impacts, the current transportation system especially in urban areas may be considered as unsustainable from various respects. To counter this challenge of moving towards sustainable transportation, much more effort is needed.
According to World Business Council on Sustainable Development (2004), sustainable mobility is defined as ‘the ability to meet the needs of society to move freely, gain access, communicate, trade, and establish relationships without sacrificing other essential human or ecological values today or in the future’. To this end, there are certain areas to focus on to mitigate transport related problems and make a transition towards sustainable transport (C2ES, 2012). Firstly, on the fuels side, transitioning to low-carbon energy sources such as biofuels or electricity from renewable resources to directly reduce emissions from fuel consumption is required. Secondly, more efficient transportation equipment is needed to run on these low-carbon fuel sources. Thirdly, increasing the efficiency of existing transportation system is needed such as applying advanced traffic monitoring and signaling. Lastly, switching from unsustainable modes (mostly personal car usage) to alternative (or sustainable) travel modes such as public transportation, walking and cycling is needed to reduce the demand for the use of more energy intensive by changing land use patterns, increasing and promoting sustainable travel options while dis-incentivizing the use of unsustainable modes. After all, it can be said that a “new mobility” is needed which is a vision of the cities in which resident no longer excessively rely on their cars but on public transportation, shared cars, bikes or walking. Therefore, there will be less pollution, less noise, less stress at the end; cities will be more livable environments.
In this direction, we are working on a mobile application project which will be capable of tracking individuals’ daily mobility activities; walking, bicycling, and driving. According to these mobility activities, the application will present the sustainability level of each individual in a sustainability scale and its related impacts on his\her health and the environment. By doing that, we aim to increase awareness of individuals for their current actions and encourage them to change their related behaviors into more sustainable ways by using different incentive and awareness tools. The application will prepare individualized packages to show people their mobility footprint with its effects on their life and on the environment and suggest other sustainable mobility ways.
Our main target group will be mostly educated people from younger and middle age groups, rich-enough to having a smart-phone, and most importantly having unsustainable mobility activities. After successfully completion of the application, as a pilot area, Education City would be a perfect place to conduct pilot experiments where members of the community are suitable to our potential customer portfolio then it can spread all over the world through Qatar and Gulf Cooperation Council (GCC) countries. By doing that, we need to tailor incentive and awareness tools towards culture and expectations of the community. In this sense, we are going to present our findings from initial phases we have conducted so far in this developing process which includes; (1) literature review, (2) market assessments via various interviews with different stakeholders and survey questionnaire with people from potential target groups to figure out their perceptions and needs regarding this behavioral change for mobility, (3) analysis of requirements based on the results from previous phase and (4) concept design which includes flow diagrams, database schema and sketching user interfaces etc. In addition to these, we will utilize Quality Function Deployment (QFD) in our concept design to transform business requirements and specs of GMAP into it. Comparison of the competitive mobile applications will be able to seen in QFD as well. GMAP intends to raise public awareness on the impacts of their behaviors, to make them healthier, to reduce carbon emissions a little by walking much more and to build a green social network who shares the same thoughts on sustainability. In short, we believe our application (when being turned into reality) will contribute orienting people into the new sustainable lifestyles or it will pave the way at least.
References
C2ES. (2012). Transportation Overview | Center for Climate and Energy Solutions. Retrieved November 9, 2015, from http://www.c2es.org/energy/use/transportation
EU Energy. (2012). Transport in Figures, Statistical Pocketbook 2012, European Commission.
Everyday Money. (2014). No Title. Retrieved November 10, 2015, from http://time.com/money/3511481/traffic-jams-cost-americans-124-billion-time-money/
Rahman, A., & Grol, R. van. (2005). SUMMA final publishable report v. 2.0; July 2005. Available Online on Http://www. Summa-Eu.Org/control/
TomTom. (2013). TomTom Congestion Index -. Retrieved from http://www.tomtom.com/en_gb/congestionindex/
WHO. (2010). Number of road traffic deaths. Retrieved November 9, 2015, from http://www.who.int/gho/road_safety/mortality/traffic_deaths_number/en/
World Business Council on Sustainable Development. (2004). Mobility 2030: Meeting the Challenges to Sustainability.
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Use of Formation Water and Associated Gases and their Simultaneous Utilization for Obtaining Microelement Concentrates Fresh Water and Drinking Water
المؤلفون: Makhkam Mamatkulov, Mashal Mamatkulov and Ikrom GulamovAbstract Purpose: The invention relates to the oil industry, inorganic chemistry, in particular, to the methods of complex processing of formation water, using flare gas of oil and gas field as fuel for producing enriched concentrates of iodine, bromine, magnesium and valuable trace elements, as well as desalinated water (technical and drinking water). The technology includes pre-cleaning of formation water from mechanical impurities and oil using adsorbents, followed by evaporation of water under vacuum, condensing water vapor in the barometric condenser, using of condensed water vapor as the coolant, using of saline water as a coolant of hot water coming out of the barometric condenser to 15–20 °C. The novelty of the design?: The novelty of the design is to get a comprehensive treatment of formation water, using flare gas of oil and gas field as fuel for obtaining enriched concentrates of iodine, bromine, magnesium and valuable trace elements, as well as desalinated water (technical and drinking water). Recycling of formation water with this method considers new directions. Worldwide the patents were received for constructing chemical plants for producing cheap food salt, killing fluid for oil wells, iodine, bromine, hydrochloric acid, caustic soda, sodium sulfate, sodium chloride, potassium bromide, sodium bromide, borax, boric acid, phosphoric acid, lithium carbonate, lithium phosphate, borax, boric acid, ammonia and carbonate products, potassium chloride, bromide and products LiCl, alkali rare elements, uranium, etc.
Hundreds of plants are engaged in the processing of brines in the world, but due to the large content variety of raw materials for each company developed its own individual process steps, depending on the climate or nearby sources of cheap heat. This is due to the fact that for concentrating and isolating the salts removal of a large mass of water required. Therefore, all businesses usually do not produce a particular product, but try to all the useful chemical elements alongside with secondary products - metals, chlorine, bromine, etc. All plants use successive allocation scheme of used salts may vary greatly from each other depending on the primary composition of the brine.
An important advantage of groundwater as a raw material source of rare elements are: the low cost of the product, because groundwater is a grade raw material, some of its geochemical types have relatively high adaptability, besides exploitation of rare elements water deposits does not require expensive mining. So in most countries (United States, Italy, Israel, Japan, New Zealand, Iceland, Australia, etc.) technological research to develop methods for extracting these elements from specific geochemical types of natural waters are constantly and systematically conducted. Cleaning the reservoir water: The technology includes pre-cleaning of formation water from mechanical impurities and oil using adsorbents. Cleaning is carried out in order to separate the unnecessary substances (organic substances) for a concentrate. Organic substances with high concentration cause by negative effects under using a concentrate and are considered to be hazardous substances in fresh water. Getting technical and drinking water and concentrate?: This technology helps to solve issues on providing facilities and public by technical water and are urgently needed, especially in those areas where there are sufficient amounts of formation waters and flare gases resources. The authors of the project developed a way for using flare gas and reservoir water for drinking water treatment and concentrates for medicine. The advantages of this technology?: Thanks to Tashkent State Technical University scientists an improved vacuum evaporation plant, was developed to split reservoir water 2 fractions - for distillate and concentrate. The advantage of this plant is that it works at lower boiling temperatures. This fact has a positive effect on the process of evaporation. Process takes place with low fuel consumption and lack of scale on the inner surfaces of the plant, since it is operated at temperatures not exceeding the limit scaling. Moreover, a significant part of the energy consumed in this process, is formed during combustion of existing flare gas, which leads to cheaper cost of the products. Using the results of this project, the production of a concentrate rich in iodine, bromine, magnesium and other minerals, as well as technical and drinking water will be ensured.
Recycling formation water and separating necessary useful from its structure we can get low cost products, as well as improve the environmental situation. In addition, solving problems with providing with of water is urgently, especially in those areas where there is sufficient amounts of formation water and flare gases resources. Water scarcity is felt in more than 40 countries (estimated at the beginning of the 21st century will reach 120–150 √ 109 m3 per year). Nearly a billion people in the world suffer from a lack of clean drinking water. This deficit can be covered by desalination of saline (salt content of more than 10 g/l) and saline (2–10 g/l) of ocean, sea and groundwater reserves totaling 98% of all water on earth.
Currently, one of the areas of energy is an efficient search of alternative methods to the traditional technologies of desalination of saline and brackish water that is the development of desalination methods of electro- spray nozzles and with subsequent evaporation and condensation. The authors of the project developed a way to use flare gas and reservoir water for drinking water treatment and concentrates.
Another advantage of the technology is solving environmental issues. These environmental problems exist in the areas where flare gases is burnt more million tons per day. Flare gas contains sulfur compounds. Sulfur compounds influences negatively on man and nature. Before the use, flare gas is purify led from compounds of sulfur, moreover, a boiler used in the technology helps complete combustion of flare gases. As a result, of flare gas, full burning decreases a rate of waste gases in the atmosphere. Technical and economic advantages of technology: The developed technology has several technical and economic advantages extraction formation water does not require much cost to obtaining it, produced water gets oil and condensates, and separated from them as by water, oil and gas fields also present flare gases of low pressure. Flare gases can be used as a source of thermal energy concentration - the result of the evaporation process of saline salty water. In addition, the next to the field “South Kemachi” there is a pond of salt water (lake “Devhona”). In the technology it is used as a coolant. In this region, there is the scarcity of fresh water. It should be noted that obtaining a concentrate rich in trace elements, from mineral water from underground using this technology is considered to be cheap raw materials and of low cost.
Lack of technologies that allow effectively utilize APG (gases rich in heavy hydrocarbons, that complicates their pumping through pipelines). Remoteness of potential markets from oil locations. Construction of pipelines to transport the petroleum to plants requires much capital investments, 1 km of the pipeline will cost more than $ 1.0 million to transport APG gas to processing enterprises from remote fields increase the cost of associated gas.
Associated petroleum gas can be used by the subsoil user as fuel in order to heat and electricity in the manner prescribed by the legislation in the field of gas and electricity and in compliance with applicable statutory rules of industrial and environmental safety.
The feature of the field “South Kemachi” is the high content of hydrogen sulfide in oil and associated petroleum gas (APG). As part of APG volume fraction of hydrogen sulfide it is about 2%. Without prior purification of hydrogen sulfide is not possible to use APG for production needs of the field and in this case the only acceptable way of dealing with it is APG flaring. Consumption of crude APG production on the deposit site is not possible. Gas contaminated with hydrogen sulfide when it is used as fuel for the boiler with prolonged exposure can lead to hydrogen embrittlement, cracking sulfide stress and/or cracking under stress corrosion in iron alloys, in other words, to a rapid deterioration of equipment.
In this project the authors consider purification associated gas from hydrogen sulfide in order to use APG purified for use as fuel for a iodine-bromine-magnesium concentrate and desalinated water and gas condensate of the field of formation water, significantly reducing the pollutants and greenhouse gases (GHG) into the atmosphere.
Reduction GHG emission achieved by the volume of natural gas, as well as in a much more complete oxidation of methane using APG as fuel compared to flaring. Flares of the deposits provide a so-called smoke spot flaring characterized by a high coefficient of unburnt gas, which leads to the release of a significant amount of methane in to the atmosphere.
Purification of hydrogen sulfide chemicals is costly.
Boiler for of desulfurization. It makes sense to include this boiler in the project due to the fact that APG is burned with total oxidation. Therefore, due to the work of the boiler methane emissions are reduced compared to flaring.
In the technology barometric condenser is used to create the vacuum that receives the amount of vapor generated by concentrating the solution and evaporation of cooling water. Certain part of the barometric condenser condensate is brought refrigerator X -1 which is the bottom of the lake “Devhona.” cooling fresh water from the cooler X-1 is brought to the barometric condenser. These regions, are short of fresh water for cooling. It is required to develop new methods for cooling.
Reservoir coolers were designed and constructed at Smolensk, Kursk, Chernobyl, South Ukrainian, Khmelnitsky, Kostroma NPP, and Surgut GRES Berezovsky; a cooling reservoir on the basis of natural lakes and depressions is in: Kalinin NPP.
A the construction of such facilities in areas where there is a lack of cooling water is very important. Recently, the amount of industrial cooling water has been increased significantly, so penetrate existing and develop new cooling methods.
Lake water have different temperatures at different depths (10 to 25 °C on the surface of 30 to 40 °C at a depth of 1 m and from 40 to 60 °C at a depth of 1.5 m). In deeper layers, the temperature is lowered at a depth of 10 m up to 18–20 °C.
In the salt lakes several types of vertical thermal structure are observed. Salt lake is a reservoir with a capacity of warm water layer between two layers of colder. In some lakes may be two “hot” zone. Often “hot” area is located in the bottom layer and in this case the vertical thermal structure of the lake consists of an upper “cold” zone and the lower “hot” as it was observed in the lake. Vanda (Antarctica), Solarium Lake Elat (Israel), in some lakes Kulunda steppe, on the Crimean peninsula, the Karakum (Dzens-Litovsk, 1957) and on the lake. Sassykkul the Eastern Pamirs (Egorov, 1991).
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The Elimination of Selenium from Contaminated Water using Sulfide or Dithionite Activated by UV Light
المؤلفون: Bahngmi Angela Jung, Aya Safan and Ahmed Abdel-WahabSelenium (Se) is an essential trace element for animals and humans because it functions as an antioxidant and catalyst for the production of active thyroid hormone. However, higher intake of Se can cause disease and death to humans. This study investigates the removal of inorganic Se (selenite, Se (IV)) from contaminated water which is known as less bioavailable and more toxic than organic forms. Several technologies exist for Se removal such as lime neutralization, bacterial reduction, ion exchange membranes, electrocoagulation, sorption, and hybrid processes such as coagulation/filtration. However, these techniques were demonstrated to be effective only at low Se concentrations levels (below 5 mg/L). This study employs an advanced reduction process (ARP) that combines a reducing agent and an activation method and investigates its applicability for Se removal at high concentrations (∼10 mg/L).
The goal of this research is to investigate the effectiveness of ARP for reducing Se (IV) to elemental Se or stable solids composing of Se and S (e.g. SeS or SeS2) in water using a combination of dithionite or sulfide as reducing agents and UV light as an activating method. Three different UV light sources including monochromatic 254 nm UV-L, UV-M with primary energy peak at 365 nm, and 312 nm UV-B were evaluated. This work studied the effects of operating conditions such as concentrations of reducing agents, solution pH, and initial selenium concentration for the optimum combination that achieves the efficient reduction of Se (IV).
In industrial applications, sulfur dioxide has been used as the reactant to reduce Se (IV) to elemental Se, but it was reported that SO2 was ineffective for Se (IV) reduction for waters with low Se concentration at room temperature. In this study, sodium dithionite and sodium sulfide were used as a strong reducing agent of interest. Sodium dithionite was proven to be an effective reductant and produce active reducing radicals when activated by UV light. It has been shown to be very effective in reducing chlorate, trichloroethylene or 1,2-dichloroethane in our earlier studies. It is known that dithionite undergoes decomposition reactions which is strongly dependent on the pH and is rapid in the acidic environment and its major decomposition products are thiosulfate (S2O3 2–) and bisulfite (HSO3–). Decomposition reaction is very complicated because its reaction products can decompose and interact with each other and can be activated by UV irradiation at various rates, which will result in the production of elemental sulfur or selenium, or precipitates of Se-S at different stages. In Se-S solution, the compounds having a general formula, SeSn (n:1–7) can be produced and it can form crystalline or amorphous composition. Therefore, we investigated the chemistry of dithionite and sulfide in Se-S water system and the behavior Se removal under UV irradiation.
Screening tests of various combinations of reducing agents and UV light types showed that the greatest Se removal (86.4%) was found with dithionite irradiated by UV-L lamp (254 nm) at around pH 5. Sulfide as a reducing reagent at neutral pH resulted in selenium removal percentages of 83.5% and 92.5% without and with UV-L irradiation, respectively. Maximum removal efficiency of Se was observed when sulfide or dithionite molar concentration was 40 times the initial Se molar concentration under UV light at given conditions. A typical color of the Se-dithionite mixture solution was milky yellow during UV-L irradiation.
Yellow-colored solids were precipitated. The combination of dithionite and UV-B (major peak at 312 nm) showed orange-colored solid in 3 hours of irradiation. It is expected that dithionite or dithionite decomposition products will produce active radicals dependent on UV light types, which may change Se-S solid chemistry. To investigate surface chemistry of solids and sulfur-containing species, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) were utilized. Also, incremental reducing agent solution injection or electrocoagulation method was utilized to reduce final Se concentration to below the maximum contaminant level.
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3D Geological Modeling with Multi-Source Data Integration for Asl Member in Rudies Formation Gulf of Suez
المؤلفون: Shaimaa RamadanBy stepwise refinement on multiple data, the method increases the accuracy of 3D models gradually and effectively. In addition, the mechanisms used in the method for organizing and manipulating information can have an equally important impact upon geologists’ thought, the interpretation of geological data, and 3D modeling methodology. A concrete example of using the method to Huai Bei fault and fold belt shows that the method can be applied to broad and complex geological areas. The technology of 3D geological modeling will bring about great changes in the methods of acquiring, storing, processing and displaying geological data. The 3D modeling methods frequently used are mainly based on plenty of 2D/3D seismic data or borehole data with cross sections between boreholes. Outlined a prospective 3D model construction method that depends on a 2.5D geological mapping anddata extraction technique. An open CORBA-based system architecture was presented that connects two existing geoscientific software tools—the geological 3D modeling and visualization tool (GOCAD) and a geophysical 3D modeling tool (IGMAS)––via a 3D Geo-database kernel. We propose a stepwise refinement method with multi-source data integration and present a comprehensive yet convenient 3D modeling system. The method can naturally simulate geological structures no matter whether the available geological data is sufficient or not. By stepwise refinement on multiple data, the method increases the accuracy of 3D modeling gradually and effectively. In addition, the mechanisms used in the method for organizing and manipulating information. 3D subsurface visualization system (SVS) has been developed. The SVS implemented in Visual C++ 6.0 and OpenGL graphics library and being able to run on the PC platform, provides a comprehensive yet convenient environment, which makes it possible for the user to build 3D models in oil exploration where there is enough available data, as well as in geological survey and mineral extraction where the geological data is insufficient. The method/SVS can be applied to broad and complex geological areas. The proposed method builds 3D models from multisource data in a stepwise manner and involves six steps: (1) integration of 2D/2.5D data, (2) supplement of cross sections, (3) Simulation of faults, (4) definition of a template, (5) construction of horizons, and (6) representation of solids. Data of different types and qualities are first merged into a 3D geologic model by data conversion interfaces. The diverse data are classified into three types: direct data, indirect data, or assistant data, depending on the type and the purpose of the information and application.
• 1-Direct data, such as borehole data and property data, is original sampling data obtained by direct observation and survey, and is highly accurate.
• 2-Indirect data, being original too, has different precision with different resolutions of graphs, such as boundaries, faults, folds and DEM derived from geological maps, topographic maps and structural geology maps, as well as 2D/3D seismic-reflection data, exploring data, etc. This type of data should be stored as files after being digitized. However, this kind of data cannot be used as direct input data for the 3D modeling system.
• 3-Assistant data will be used in the process of 3D modeling as icons like 2D/3D primitives, and texture maps including satellite or aerial imagery, scanned maps, etc. The research in the past has focused on generating 3D models from borehole and cross-section data. This has limitations, however, since these data are lacking in many areas. In this section, we emphasize on how to use data of different types and qualities, as well as various mathematical methods to gradually refine 3D models to a desired accuracy.
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Life Time Stability Study of PCDTBT:PC71BM Solar Cells with the Organic-inorganic Hybrid Hole Transport Layer Fabricated in Various Atmospheric Conditions
المؤلفون: Saqib Rafique, Khaulah Sulaiman and Shahino Mah AbdullahBulk heterojuntion organic solar cells (BHJ OSCs) have gained much attraction in recent years. These solar cells have layered geometric structure and optimization of each layer is essential to achieve the overall performance of the device. Active layer consisting of donor and acceptor material is sandwiched between two electrodes. In order to improve the device stability and efficiency, often interfacial layers, namely electron and hole transport layers, between the active layer and electrodes are introduced. Poly (3.4-ethylenedioxythiophene): Poly (styrenesulfonate) (PEDOT:PSS) is most commonly applied hole transport layer (HTL) in OSCs. However, it limits the device performance due to its highly hygroscopic and acidic nature which arise reliability issues while reducing the cell life drastically. Metal oxides have been proved to be a good alternative to it. These metal oxides improve the device efficiency comparable with standard HTL and at the same time they substantially enhance cell stability. The aim of this work is to optimize the hole transport layer by using different metal oxides such as vanadium pentaoxide (V2O5) by improving its structural, optical, and electrical properties. V2O5 has been extensively studied as a promising candidate for charge extraction and transportation because of its exceptional electronic properties. It proved to be more stable due to its good transparency, low resistance and better adhesions to the active layer. The novelty of our study is to develop a highly controllable, reproducible and cost effective fabrication technique to build our device with poly [N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3’-benzothiadiazole)] (PCDTBT), and (6,6)-Phenyl C71 butyric acid methyl ester (PC71BM) based active layer yielding high stability and efficiency. This work is focused on improving the device stability along with the efficiency which has not been explored much to date.
In this work, we demonstrate the fabrication of PCDTBT:PC71BM based bulk heterojunction solar cells with two variants of hole transport layer (HTL) in different fabrication atmospheres. Device with standard PEDOT:PSS hole transport layer has been compared with its organic-inorganic (V2O5 in PEDOT:PSS) hybrid variant in terms of efficiency and life time stability when they are fabricated in controlled mode in the nitrogen filled atmosphere and an ambient mode in the presence of oxygen and 65% relative humidity (RH). Vanadium pentaoxide (V2O5) nanoparticles, synthesized by co precipitation method, are mixed in PEDOT:PSS layer to form an organic-inorganic hybrid HTL. Both variant of hole transport layer are further characterised for their structural and optical properties to optimise these fundamental properties to ensure highly stable and efficient solar cell. Normalized efficiencies are calculated as a function of time for life time stability tests of both types of devices fabricated in both atmospheric modes. The best performance is achieved for a device with hybrid HTL fabricated in controlled mode where the life time stability has improved from 70% to 94% over one week period and from 65% to 90% over four week time when they are compared with their standard PEDOT:PSS HTL counterpart. Our results confirm that fabrication environment play a key role in device performance in terms of stability and efficiency along with the improvement brought by addition of V2O5 nanoparticles in the pristine PEDOT:PSS hole transport layer.
Keywords: Hole transport layer; Organic solar cells; PEDOT:PSS; Stability; V2O5
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Experimental and Numerical Analysis of Heat Transfer in Grooved Tubes for Solar Collector Applications
المؤلفون: Ben Alex Baby and Y. Raja SekharSolar thermal energy research and utilization is progressing rapidly since it is clean energy and can achieve carbon credits in developed and developing countries. The energy conversion efficiency of most of the solar collectors is low, as much of the energy absorbed by collectors is lost due to transient atmospheric conditions. Reduction of losses and improving the performance of collectors by providing economical solutions has been the greatest challenge that scientists are facing even today. Material technology has achieved highest boundaries in all the applied fields ranging from medical to space. According to literature, the use of nanofluids in thermal devices improves the performance thereby further increasing the thermal conversion efficiency of solar collectors. The work here aims at numerically and experimentally studying the heat transfer enhancement obtained as a result of introducing grooved tube collector and using ZnO nanofluid as the working media in a solar flat plate collector. Helical grooves of different pitch are made in collector tubes that generate a spin flow which would increases the heat transfer rate at the expense of increased pressure drop. The convection heat transfer is enhanced as a result of flow through these grooved tubes which is the reason for the absorption efficiency increase. Heat transfer augmentation increase in grooved and plain tubes is compared here. Heat transfer augmentation is expected to increase when compared to a plain tube and a comparative analysis is carried out on the basis of the heat transfer coefficient, wall shear stress at constant Reynolds number and constant mass flow rate condition. The improvement in absorption efficiency at two different groove depth (e/d = .023, .0175) and varying flow velocity is also studied. The use of nanofluid has been a recent technological advancement as the metal/metal oxides dispersed in a base medium improved the absorptive solar energy by up to 95% which further increasing the thermal conversion efficiency. ZnO nanofluids are prepared by economical methods at different volume concentrations. The particle concentration is one determining parameter and on increasing the concentration the heat transfer properties show a rise up to a maximum value and beyond which it decreases. The numerical analysis here is done for ZnO nanofluid with particle concentration varying from .5%–2%. The synergic effect of the two improvements in the heat transfer and fluid flow characteristic is studied experimentally and numerically in the transition and turbulent flow regimes.
Keywords: Flat plate collector, grooved tube, Heat transfer coefficient, Reynolds number, ZnO nanofluid
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Stem Cell-Based Selective Delivery of Alpha Keto Reductases for Therapeutic Targeting of Residual Androgens in Metastatic Prostate Cancer
المؤلفون: Asim B. Abdel-MageedIntroduction: The de novo synthesis and “intracrine” production of androgens by prostate tumors provides a significant survival advantage leading to the outgrowth of castration resistant tumors. Currently, targeting residual androgens in metastatic prostate cancer (PC) microenvironment is the toughest challenge in the clinical management of advanced PC patients treated with androgen ablation therapy (AAT), as they are implicated for development of castration-resistant PC (CRPC). Our previous studies (Stem Cells, 2014) demonstrate that PC-derived adipose derived stem cells (pASCs) promote tumor growth and undergo PC mimicry through neoplastic reprogramming. The present study examines the role of pASCs in synthesizing and producing and rogens and its potential in supporting growth of hormone-dependent PC cells under castrate conditions in vitro and in vivo. Further more, the study attempts to identify key players among the and rogen-metabolizing enzymes (AMEs) in the backdoor pathway for targeting and degradation of androgen synthesis in the prostate tumor microenvironment, by both in vitro and in vivo assays. Methods: Based on an IRB approved protocol, the pASCs were isolated from fatt issues procured from PC patients undergoing radical prostatectomies. The purity of the pASC isolates was validated by FACS analysis and differentiation assays. The ability of pASCs exposed to PC-derived conditioned media (CM) to produce androgens was monitored by expression of AMEs (PCR) and androgen release (EIAkit). The ability of pASC CM to support growth of androgen-dependent LNCaP cells was assessed by MTT assay and growth of LNCaP tumors co-transplanted with pASCs in castrated mice in vivo. Normal donor-derived adipose derived stem cells (nASCs) were enriched for tumor tropicity by a transwell system. Next, we subcloned in a GFP bicistronic IRES lentivirus construct (pLVX-IRES-ZsGreen1) the rat androgen hydrolyzing enzyme 3α-hydroxysteroid dehydrogenase (Type I, 3α-HSD), as known as AKRIC14, in-frame with IL-2SS sequence at the N-terminus. R1C14. The ILL2SS sequencec enables the AKR1C14 by the transduced cells. Upon transduction, the enriched nASC population was monitored for the transgene expression and release by qRT-PCR, immunoblotting and EIA kit. The efficacy and functional activity of the recombinant enzyme and the nASC-released ANR1C14 enzyme were monitored by MTT, LDH and luciferase reporterassays in the androgen-dependent LNCaP cells in vitro. The tumor-homing potential of the GFP-AKRC14 expressing nASCs infused by IV route was validated by their engraftment in LNCaP tumor-bearing mice. To examine the efficacy of secreted enzyme to hydrolyze androgens andinduce tumor regression in vivo, the GFP-AKR1C14 transduced nASCs were injected in mice bearing LNCaP tumors and tumor volumes were measured weekly. Results: We demonstrate here in that unlike normal adipose-tissue derived stem cells (nASCs), the PC cell microenvironment subverts tumor-tropic PC patients' derived ASCs (pASCs) to synthesize and produce androgens in the tumor microenvironment. The pASC-mediated hormone production was sufficient to support the growth of androgen-dependent LNCaP PC cells in vitro under hormone-deprivation conditions as well as in castrated nude mice. Comparative analysis of gene expression of AMEs in microdissected cells versus the adjacent normal tissue revealed AKR1C4, an alpha keto reductase, to be the most promising candidate for targeting the backdoor pathway in dihydrotestesterone (DHT) synthesis. Type 1 3α-HSD enzyme has been shown to readily oxidize testosterone to Δ4-androstene-3, 17-dione in a substrate dependent reaction. The recombinant AKR1C4 induced cytotoxicity and apoptosis in androgen-dependent PC cells in vitro. Next, using a GFP bicistronic IRES lentivirus construct, we demonstrate that the genetically engineered tumor-tropic nASCs enable expression and secretion of AKR1C14. The results showed that the engineered nASCs are capable of expressing the enzyme, which in turn catabolizes androgens in vitro and induce apoptosis in androgen-dependent LNCaP cells. The AKR1C14 transduced nASCs successfully engrafted in and reduced growth of LNCaP tumors in nude mice. Conclusions: Together, our data demonstrates that selective delivery of alpha keto reductases by nASCs could eliminate residual androgens and further paves the way for their potential use in combination with AAT for treatment of CRPC.
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The Impact of Bariatric Surgery on Neuropathic Pain and on Objective Markers of Neuropathy
Background: Obesity (BMI ≥ 30 kg/m2) is associated with T2 diabetes (40-fold relative risk) and cardiovascular complications. Bariatric surgery is becoming a treatment of choice in obese individuals because of the multiple benefits associated with significant weight loss leading to an improved quality of life and decreased morbidity and mortality, which far out weighs the cost of surgery. A major metabolic benefit is the remission from T2 diabetes as a consequence of alterations in gut hormone signaling and weight loss. Indeed cost-effectiveness analyses have led NICE to recommend that all patients with a BMI ≥ 35 kg/m2 with T2 diabetes should be considered for bariatric surgery. In relation to the impact on macro vascular complications there is a significant reduction in MI and stroke in long term follow up studies, which translates to reduced mortality. For the microvascular complications of diabetes, studies are limited but have primarily focused on retinopathy and nephropathy after bariatric surgery. Despite the fact that neuropathy (nerve damage) can lead to pain and foot ulceration with amputation together with increased mortality from autonomic neuropathy, few studies have objectively assessed the impact of bariatric surgery on neuropathy. However, there are concerns that neuropathy could worsen following bariatric surgery due to nutritional deficiencies [1] and indeed there are case-reports of acute Guillain-Barre like demyelinating [2] and motor axonal [3, 4] neuropathy following bariatric surgery. The term post bariatric surgery neuropathic pain has also been coined with a reported prevalence of 33% following bariatric surgery [5]. However, a more recent study has shown complete resolution of neuropathic symptoms with an improvement in the neuropathy disability score [6]. Whereas a recent case-control study has showed no improvement in nerve conduction velocity [7]. Given the potential benefits and indeed harm following bariatric surgery there is a need for a systematic quantitative assessment of neuropathy to define true rates of remission or worsening. Aims: Systematically define the baseline prevalence of neuropathic pain and neuropathy and the outcomes following bariatric surgery on neuropathic pain and objective markers of somatic and autonomic neuropathy in obese subjects with and without T2 diabetes, 6 and 12 months after surgery. Methods: This is a prospective, randomized, single center trial assessing the effect of gastric bypass surgery. The subjects in the study were recruited from Salford Royal NHS Foundation Trust, UK and the study was performed at the Wellcome Trust Clinical Research Facility/NIHR, Manchester, UK from 3 September 2013 until 30 July 2015. We estimated that the minimum sample required to detect a significant difference in peripheral autonomic (Neuropad response) and sensory nerve morphology using the novel imaging technique of corneal confocal microscopy (CCM) to quantify corneal nerve fibre length (CNFL) over 12 months was 52 and 46 subjects, respectively with a power of 80%. Exclusion criteria included history of neuropathy due to non-diabetic cause and corneal trauma or surgery. Painful neuropathy was defined using a composite score of the McGill questionnaire with either a positive neuropathic symptom profile (NSP) or diabetic neuropathy symptom (DNS). The objective end-points for remission from neuropathy were: 1) >15 nerve branches/mm2 in corneal nerve branch density (CNBD) and >15 mm/mm2 in corneal nerve fibre length (CNFL), 2) for autonomic neuropathy >90% on the Neuropad response, and 3) for sensory neuropathy, < 2 on the neuropathic disability score (NDS) and < 15 Volts for vibration perception threshold (VPT). The Local Research Ethics committee approved this study and all subjects gave informed consent to take part in the study. The research adhered to the tenets of the declaration of Helsinki. Results: Of 106 subjects recruited, 40 refused and 23 are awaiting follow-up assessments. We have analysed 43 subjects with an average age of 52.2 ± 2.1 years. Baseline BMI was 50.6 ± 2.8 kg/m2 and was significantly reduced to 38.2 ± 1.4 kg/m2 (P < 0.0001) and 35.8 ± 1.7 kg/m2 (P < 0.0001) at 6 and 12 months, respectively. 26/43 (60%) of subjects had T2 diabetes before surgery. Based on normalization of HbA1c the remission rate from diabetes was 81% 12 months after surgery. Baseline HbA1c in 26 subjects with T2 diabetes was 7.4 ± 0.3% and was significantly reduced to 5.9 ± 0.2% (P = 0.0007) and 5.6 ± 0.1% (P < 0.0001) at 6 and 12 months, respectively. Hypertension (Systolic BP >120 mmHg) was identified in 37/43 (86%) of subjects pre-surgery. The remission rate from hypertension was 57%, 12 months after bariatric surgery. The average starting systolic blood pressure in these subjects was 130.3 ± 2.7 mmHg and was significantly reduced to 120.8 ± 3.13 (P = 0.03) and 114.4 ± 5.49 (P = 0.008) at 6 and 12 months, respectively. The prevalence of sensory neuropathy assessed using the Neuropathy Disability Score (NDS) in 41 subjects was 34% pre-surgery and the remission rate was 50%, 12 months after surgery. Baseline NDS was 2.0 ± 0.4, indicative of minimal neuropathy but was significantly improved to 0.89 ± 0.4 (P = 0.05) at 12 months. Vibration perception threshold was 13.6 ± 1.25 V and showed no improvement (12.6 ± 1.46 V, P = 0.58) 12 months after surgery. The prevalence of neuropathic pain in 36 subjects was 39% pre-surgery and a complete recovery was observed in 71% and 93% of patients at 6 and 12 months, respectively. Likewise, 45% of the 22 subjects with T2 diabetes had neuropathic pain at baseline and 70% and 90% had no painful neuropathy at 6 and 12 months, respectively. The prevalence of peripheral autonomic dysfunction assessed using Neuropad in 24 subjects was 57% pre-surgery and the remission rate was 69% 12 months after surgery. The Neuropad response at baseline was 77.95 ± 5.1% and improved significantly (91.3 ± 3.86%, P = 0.04) 12 months after surgery. Corneal confocal microscopy showed a significant increase in corneal nerve fibre length in the 26 subjects with diabetes from a mean of 14.2 ± 0.7 mm/mm2 to 16.7 ± 1.04 mm/mm2 (P = 0.049) and an increase in corneal nerve branch density (32.8 ± 3.35 no./mm2 to 43.2 ± 4.49 no./mm2 (P = 0.068). However, there was no change in corneal nerve fibre length or branch density in 17 subjects without T2 diabetes 12 months after surgery. Conclusion: Our study shows a high prevalence of diabetes; hypertension, neuropathic pain and neuropathy assessed using objective measures of somatic and autonomic neuropathy in obese people. Bariatric surgery results in significant weight loss, and improved glycemic control and blood pressure, with a reduction in the prevalence of painful neuropathy and improvement in autonomic and in particular small fibre neuropathy assessed using corneal confocal microscopy. Morbid obesity is common (-30%) in the Qatari population and bariatric surgery is an increasingly performed procedure. Contrary to previous data showing a worsening of both neuropathic symptoms and deficits, our data show significant weight loss with an improvement in glycaemic control and blood pressure which improves neuropathy and therefore provide a strong rationale for undertaking bariatric surgery and reducing disabilities to reach the goals of VISION 2020-Qatar.
References
1. Thaisetthawatkul, P., et al., A controlled study of peripheral neuropathy after bariatric surgery. Neurology, 2004. 63(8): p. 1462-70.
2. Ishaque, N., et al., Guillain-Barre syndrome (demyelinating) six weeks after bariatric surgery: A case report and literature review. Obes Res Clin Pract, 2015. 9(4): p. 416-9.
3. Landais, A., Neurological complications of bariatric surgery. Obes Surg, 2014. 24(10): p. 1800-7.
4. Landais, A.F., Rare neurologic complication of bariatric surgery: acute motor axonal neuropathy (AMAN), a severe motor axonal form of the Guillain Barre syndrome. Surg Obes Relat Dis, 2014. 10(6): p. e85-7.
5. Kattalai Kailasam, V., et al., Postbariatric surgery neuropathic pain (PBSNP): case report, literature review, and treatment options. Pain Med, 2015. 16(2): p. 374-82.
6. Muller-Stich, B.P., et al., Gastric bypass leads to improvement of diabetic neuropathy independent of glucose normalization-results of a prospective cohort study (DiaSurg 1 study). Ann Surg, 2013. 258(5): p. 760-5; discussion 765-6.
7. Miras, A.D., et al., Type 2 diabetes mellitus and microvascular complications 1 year after Roux-en-Y gastric bypass: a case-control study. Diabetologia, 2015. 58(7): p. 1443-7.
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The Role of 4-hydroxynonenal in Human Preadipocyte Proliferation and Differentiation
Accumulation of lipid peroxidation products in response to oxidative stress can cause dysfunction and pathology in a variety of tissues. In this study, we investigated the presence of 4-hydroxynonenal (4-HNE), the most abundant lipid peroxidation end product, in paired subcutaneous (SC) and omental (OM) tissues obtained from morbidly obese individuals undergoing weight reduction surgery. We further assessed 4-HNE effect on proliferation and differentiation of preadipocytes derived from these tissues in two metabolically distinct groups. Levels of 4-HNE accumulation were positively correlated between the paired SC and OM tissues (R2 = 0.9, p = 0.01) and exhibited a higher accumulation in OM-adipocytes and connective tissues compared to SC-derived counterparts. Exposure of tissues-derived preadipocytes to physiological levels of 4-HNE caused inhibition of proliferation and differentiation of SC, but not OM-derived preadipocytes. When samples were dichotomized into insulin sensitive (IS) and insulin resistant (IR) groups based on their HOMA-IR index, 4-HNE treatment caused a greater reduction of both proliferation by 76% with a mean difference of 11.4% (3–45.3) and differentiation capacity by 56% with a mean difference of 25.9% (3.9–55.7) in IS compared to IR. This data suggest that 4-HNE induced oxidative stress plays a role in the regulation of adipocyte proliferation and differentiation in a depot and insulin sensitivity-specific manners and may therefore contribute to metabolic dysfunction associated with insulin resistance. This research was sponsored by Qatar National Research Fund (QNRF), Grant number NPRP6-235-1-048.
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Alpha-Synuclein Oligomers as a Biomarker Candidate for Parkinson's Disease and Disorders
المؤلفون: Omar El-AgnafDeveloping effective treatments for neurodegenerative diseases is one of the greatest medical challenges of the 21st century. Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are very common neurological disorders of the elderly (Jankovic et al., 2008). Although many of these clinical entities have been recognized for more than a hundred years, it is only during the past fifteen years that the molecular events that precipitate the diseases have begun to be understood. Mutations in the α-synuclein gene cause early-onset PD, often associated with dementia, and one an α-synuclein mutation segregated with pure DLB (with no Alzheimer's pathology). Neuropathologically these diseases are characterized by the presence of Lewy bodies, intraneuronal inclusions mostly composed of α-synuclein protein fibrils, cementing the notion that this protein has a central role in Lewy body diseases (LBD). Despite the progress that has been made in understanding the underlying disease mechanisms of LBD, there remains an urgent need to develop methods for use in diagnosis. The development of reliable surrogate markers for the presence and abundance of α-synuclein lesions (Lewy bodies) in the brain would naturally facilitate a more streamlined work-up during the early care of PD and DLB patients, and importantly, allow for the biologically guided evaluation of future drug trials aimed at neuroprotection in the synucleinopathies. Recently, we generated new antibodies specific for different forms of α-synuclein such as oligomeric-α-synuclein (o-α-synuclein), phosphorylated-α-synuclein at serine 129 (p-S129-α-synuclein) or total-α-synuclein (t-α-synuclein), to develop highly specific and sensitive ELISA systems to assess the levels of these species in biological fluids. Next, we utilized our assays to explore the potential use of α-synuclein species as biomarkers for PD in cerebrospinal fluid (CSF) samples from a cross-sectional cohort of 46 PD patients and 48 age-matched healthy controls. Thereafter, we validated our results in large longitudinal DATATOP cohort (n = 242) over two-year follow-up period). In our study we also investigated the potential predictive role of CSF Alzheimer's disease (AD) core biomarkers (Aβ42, total tau, p-tau). In our study we also investigated the added predictive value of CSF AD core biomarkers (Aβ42, total tau, p-tau) to CSF α-synuclein species. Interestingly, a strong positive correlation between the changes in CSF t- and o-α-synuclein levels was noted. Such a strong correlation clearly suggests that the increase of CSF t-α-synuclein levels at the early stages of the disease lead to the formation and accumulation of the pathogenic species of o-α-synuclein in the brain that cause neuronal cell death. It has been shown that soluble o-α-synuclein are elevated in brain homogenates from PD and DLB compared to normal brains (Sharon, et al., 2003; Paleologou, et al., 2009). Together with the results from our previous studies, we provide strong evidence for the important role of o-α-synuclein in the pathogenesis of PD and other synucleinopathies (El-Agnaf et al., 2003). Consistent with our recent study (Parnetti, et al., 2014), we also found that the change in CSF Aβ42 levels correlated with the change in UPDRS-mental scores, suggesting that CSF Aβ42 may aid in predicting cognitive decline in PD patients. It's worth mentioning that one of the many important features that distinguished the DATATOP study from other studies is that the untreated PD subjects enrolled in the DATATOP study were at a very early stage of the disease; a stage estimated to be earlier than most of the other clinical trials. At baseline, PD patients presented with minimal disability and were followed until just prior to the initiation of the dopamine replacement therapy, and this is reflected in the low H&Y scores registered for these patients. This limited motor disability may explain the lack of an association between the baseline or follow-up CSF biomarkers and disease severity. However, the significant changes of CSF α-synuclein levels we observed in the DATATOP cohort over approximately two years of disease progression, suggest that a correlation between CSF α-synuclein levels and clinical parameters will become apparent with longer follow-up. However, our findings still need to be further validated in large-scale, prospective and well-controlled studies, especially those that include subjects with neuroimaging-supported definite PD and healthy controls such as the on-going Parkinson's Progression Markers Initiative. Synucleinopathies and tauopathies show significant clinical and pathological overlap, making the early diagnosis of PD more challenging. This overlap necessitates a combination of measurements of CSF α-synuclein species with AD key biomarkers to improve diagnostic accuracy. Our cross-sectional analyses revealed a positive correlation between CSF t-α-synuclein and t-tau and p-tau in the PD group. Our findings confirm and extend the observations by Toledo and his colleagues who reported a positive correlation between CSF t-α-synuclein and tau levels in PD, AD and controls (Toledo et al., 2013). These data suggest that the elevation of CSF tau and t-α-synuclein reflect synaptic degeneration and axonal loss. To our knowledge, this is the first study that combines measurements of different species of α-synuclein, along with AD biomarkers, and showed significant changes of CSF α-synuclein species in large longitudinal study at the early stages of PD. Taken together, these data suggest that the levels of t-, o- and p-S129-α-synuclein species change over the natural course of the disease, and thus might aid in monitoring disease progression and severity. This supports our hypothesis that changes in CSF α-synuclein species are a more direct measure of the formation of LBs and Lewy neurites, which are the hallmarks of PD pathology. Our findings study demonstrated that quantification of α-synuclein species in CSF has strong potential value as a tool not only for PD diagnosis but also for presymptomatic screening of high-risk individuals who are good candidates for neuroprotective treatment.
References
El-Agnaf OM, Walsh DM, Allsop D. Soluble oligomers for the diagnosis of neurodegenerative diseases. Lancet Neurol 2003;2:461–462.
Jankovic, J. Parkinson's disease: clinical features and diagnosis. J Neurol Neurosurg Psychiatry 2008;79:368–376, doi:10.1136/jnnp.2007.131045.
Kordower, J. H. et al. Disease duration and the integrity of the nigrostriatal system in Parkinson's disease. Brain 2013;136:2419–2431, doi:10.1093/brain/awt192.
Paleologou, K. E. et al. Detection of elevated levels of soluble alpha-synuclein oligomers in post-mortem brain extracts from patients with dementia with Lewy bodies. Brain 2009;132, doi:10.1093/brain/awn349.
Parnetti, L. et al. Differential role of CSF alpha-synuclein species, tau, and Aβ42 in Parkinson's Disease. Front Aging Neurosci 2014;6:53, doi:10.3389/fnagi.2014.00053.
Sharon, R. et al. The formation of highly soluble oligomers of alpha-synuclein is regulated by fatty acids and enhanced in Parkinson's disease. Neuron 2003;37:583–595.
Toledo, J. B., Korff, A., Shaw, L. M., Trojanowski, J. Q. & Zhang, J. CSF α-synuclein improves diagnostic and prognostic performance of CSF tau and Aβ in Alzheimer's disease. Acta Neuropathol 2013;126:683–697, doi:10.1007/s00401-013-1148-z.
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Exploring Depression Amongst Cardiovascular Patients Living in the State of Qatar – Findings from a Cross-Sectional Study
المؤلفون: Tam Truong DonnellyIntroduction
Cardiovascular diseases are the leading cause of death. Studies show that depression is associated with an increased morbidity and mortality among cardiovascular (CV) patients. Depression contributed to patients’ unfavorable prognosis after a cardiac event, hamper cardiac rehabilitation, and increase hospital re-admission rate among CV patients. Studies show that 15 – 30% of CV patients experience depression. Early detection and intervention for depression among cardiovascular patients can reduce morbidity and mortality rates. Understanding factors contribute to the risk of depression and its management among cardiovascular patients is necessary to adequately address the complex nature of depression as co-morbidity among Arab CV patients in the Middle East region. Objectives: (1) To evaluate the prevalence and severity of depression among patients who have confirmed diagnosis of cardiovascular diseases; and (2) To find ways to manage depression among male and female Arab CV patients. Methods: Using non-probability, convenient sampling method, a cross-sectional survey was conducted with 1000 Arab CV patients of which 688 (69%) male and 312 (31%) females between January, 2013 and September, 2014 at the Heart Hospital in Qatar. Inclusion criteria were ≥ 20 years of age, agreeing to participate in the study (98% response rate), and having final confirmation of acute cardiac conditions. Face-to-face interviews were conducted using structured survey questionnaires which included an Arabic demographic questionnaire and the Arabic version of the Beck Depression Inventory 2nd Edition (BDI-II) - a self-report instrument, which had been translated into Arabic and validated for its validity and reliability. Descriptive and inferential statistics were performed using SPSS version 20. Results: Almost half of the male and female participants were Qatari nationals (46%). Citizens of the Levant countries (Syria, Lebanon, Palestine, Jordan) constituted 20% and North African countries (Egypt, Libya, Tunisia, Algeria, Morocco) constituted 17% of the participants. 80% of the patients had no depressive symptoms, 15% of the patients had Mild Mood Disturbance and 5% had symptoms of clinical depression. Almost twice as many females (29%) than males (16%) were found to suffer from Mild Mood Disturbance and Clinical Depression. Approximately half of both male and female patients who scored ≥ 17 on the BDI-II (suggesting symptoms of clinical depression) refused psychiatric assistance. Chi Square tests indicated that age and socioeconomic factors, nationality, marital status, monthly income, employment, occupation, financial stress and support were significantly related to gender and depression (all p < 0.001).
Conclusion: (1) In-depth systematic assessment of mental health status and screening for depression should be performed routinely for all patients who had diagnosed with cardiovascular diseases, particularly females.
(2) Public awareness and education about mental health are critical in order to reduce the stigma associated with accessing treatment for it.
(3) Practices, treatments and diagnostic tools for depression should be thoroughly investigated and adapted to the Arab Middle Eastern context in order to facilitate the development of culturally appropriate mental health care and uptake of cardiac interventions and rehabilitation.
(4) Health policy makers should encourage and support psychiatric training and primary health care providers should be trained to provide psychiatric assistance to CV patients.
(5) Socioeconomic related factors influence the mental health of male and female CV patients differently and accordingly their CV conditions and outcomes.
(6) To effectively manage and treat depression among Arab CV patients, health care providers should be encourage to integrate gender differences approach into clinical practice.
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Derivation of Hepatocyte Like Cells from Human Pluripotent Stem Cells in GMP Compliant Conditions
المؤلفون: Imbisaat GetiThe liver is the largest internal organ in the human body and performs a broad range of functions. Hepatocytes are the primary cells of liver. They perform many functions, an endocrine function, secretion of most proteins found in the blood plasma including albumin, exocrine functions and secretion of bile into the digestive tract. They are also involved in carbohydrate and lipid metabolism, drug detoxification and storage of glycogen. In addition, the liver has a unique capability of regeneration as the liver can fully regenerate itself following severe damage which leaves one-third of the cells uninjured (Michalopoulos, 1997; Taub, 2004). Liver disease and progressive loss of liver function is a major clinical challenge. Liver disease is the fifth highest cause of early mortality in the UK and the only cause of death that is increasing every year (Office for National Statics., 2008). With changes in lifestyle, new diseases such-as non-alcoholic fatty liver disease and steatohepatitis, a lack of hepatitis C vaccination and risk of hepatocellular carcinoma in hepatitis patients with increasing age are further compounding the problem of liver disease in the UK (Bosch et al., 2004; Kim et al., 2002) Currently liver transplantation is the only treatment available for end stage liver disease and a few liver based metabolic defects (Sze et al., 2009). Split liver transplantations is available and makes more transplants possible but ultimately is not sufficient to fulfill the growing need. Cell-based therapy involving the transplantation of primary hepatocytes could greatly expand the number of patients provided with effective treatment. However, primary hepatocytes are difficult to obtain in sufficient number. Indeed, they can only be obtained from organs suitable for transplantation as they cannot be expanded in vitro. These limitations can be overcome by using human Embryonic stem cells (hESCs) or induced pluripotent stem cells to differentiate into hepatocytes. Stem cells have great potential because of their self-renewable capacity differentiation potential including differentiation into hepatocytes (Hannan et al., 2013; Si-Tayeb et al., 2010; Sullivan et al., 2010). In our lab Hannan et al. have previously published an efficient and robust protocol to differentiate human stem cells to hepatocyte-like cells in a stepwise manner using defined factors. Human pluripotent stem cells (hPSCs) hold several clinical promises including the potential to produce large quantity of cells necessary for cell based therapy approaches. Hence, hPSCs provide an advantageous alternative since they can be differentiated into hepatocyte-like cells which display functional characteristics of their in vivo counterparts. However, there are two major limitations that must be overcome before this approach can go to clinical trials. Firstly current protocols are not GMP (Good Manufacturing Practice) grade. Secondly, hepatocytes-like cells derived in-vitro lack a several characteristics of adult hepatocytes and express fetal markers indicating that they are not fully functional. Here, I aim to develop a method to generate hepatocyte-like cells from hPSCs in conditions compatible with clinical applications. For that, I have developed a culture system to generate hepatocyte-like cells using culture conditions compatible with GMP. The resulting cells display characteristics of their in vivo counterpart and represent a first step toward the development of cell based therapy for liver diseases. In my study, as far as we know I am the first to have translated differentiation of hepatocytes-like cells into GMP-compliant conditions. Here, I report a method to translate our previously published efficient and promising step-wise hPSCs directed research grade differentiation protocol for the generation of hepatocytes-like cells under GMP-compliance conditions, demonstrating that this can be attained and hepatocytes-like cells can be produced at a standard suitable for clinical trail purposes. In general, the employment of cell-based products in clinical studies needs formal approval from the respective regulatory body (British Standards Institution, London, UK). According to the current national regulations this approval requires manufacturing, processing and testing of cellular products (Bailey et al, 2014). The manufacturing of cell product requires use of safe and pure components and materials in order to fulfil the regulatory standards. It is essential to use stable and clinical grade hESCs cell lines that first generated and preserved in GMP banks which provided effective, safe cell source as starting material. If possible, licensed and GMP-grade materials must be used, in case of no alternatives, highly purified xeno-free or animal-free research grade reagent should be used, with additional in-house testing to ensure safety and quality. The translated protocol fulfills all the above criteria. Depending on the availability in the market the translated protocol has GMP compliant materials wherever possible. When no GMP grade material was available I used preclinical, xeno-free reagents from reputed suppliers. I tested 9 cell lines: two control cell lines derived in research grade (H9 and BBHX8) and 8 fully GMP grade (mShef3, mShef4, mShef7, mShef8, mShef10, mShef11, Val9). The matrixes used for maintenance and differentiation and hESC lines are fully GMP grade. The growth factors and supplements used are GMP grade apart from OncostatinM and HGF, which are soon-to-be GMP grade as promised by the manufacturer and are currently under preclinical version. The media used are GMP grade apart from hepatozyme, which is a serum free medium. Small molecules used are all GMP grade apart from LY294002, which is highly purified HPLC grade. In Addition, freezing medium, reconstitution reagents, splitting reagents, PBS, water etc. are all GMP grade. Both GMP grade and RG HPSCs cell lines maintained their pluripotency in GMP maintenance conditions and were karyotypically normal when karyotyped every 10 passages for 40 passages. Expression of all pluripotent markers was observed. These finding showed that the GMP maintenance conditions are robust, effective and good enough that cell grown in RG condition can also be transferred and maintained. I was able to generate hepatocytes-like cells expressing hepatic markers from mshef3, mShef7, mShef11, H9 and BBHX8. When compared to H9 GMP compliant derived hepatocytes-like cells these differentiated cell lines showed similar protein and gene expression, mShef3 being an exceptionally good cell line having 10 fold increase in Cyp3A4 and tyrosine aminotransferase (TAT). When analysed for the functionality mSef7, BBHX8 showed similar level of Cyp3A4 activity while mShef3 was 7 folds higher expressed. Here, I report successful translation of HPSCs differentiation protocol in hepatocytes-like cells into GMP-compliant conditions by using HPSCs derived in a fully GMP manner and changing into defined feeder and serum free differentiation media and supplements to GMP- compliant conditions.
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Job Stress and Job Satisfaction Among Health Care Professionals
المؤلفون: Abdul SalamBackground: Workplace stress can lead to poor health and work-related injuries. Health care professionals comprise an important group of individuals who are affected by emotional states and stress because of their unique work environment. The employee's stress level and satisfaction with his/her job are primary factors that influence the quality of work and individual productivity. In health care, employee job stress can have a negative impact on the quality of patient care. Among this group, studies have found various causes of stress, including varied working hours, heavy work load, night shifts resulting in sleep deprivation, imbalance between work and life, isolated feelings, and minimal control over the workplace accompanied by minimal autonomy. Results of various researchers show that stress, fatigue, burnout, depression, and general psychological distress negatively affect health care systems and patient care. While there are a few published studies examining the prevalence of stress and job satisfaction among health care professionals in the Middle East, no such studies are available from Kingdom of Saudi Arabia (KSA). Objective: To measure the prevalence of job stress and job satisfaction among healthcare professionals and to identify potential factors that could affect job stress or satisfaction among health care workers were also explored. Research Design: The design of this study was a quantitative, multi-center, cross-sectional, correlational study where job stress and job satisfaction validated questionnaires were administered to randomly selected health care professionals working at National Guard Health Affairs, Eastern Region, Kingdom of Saudi Arabia. A total sample size of 620 subjects was needed to produce a two-sided 99% confidence interval (44.8%–55.2%), with an effect size of 5.2%. Subjects: Physicians, residents, nurses, and radiologists working at National Guard Health Affairs, Eastern Region, Kingdom of Saudi Arabia. Measures: Job stress and satisfaction were measured using 25 specific questions about sources of work-related stress and 17 questions about sources of work related satisfaction. Demographic and job characteristics variable data were also collected.
Statistical Methods Descriptive results for all demographic variables, job characteristics, and socioeconomic factors were reported using mean ± standard deviation (SD) and number (percentage) as appropriate. Logistic regression analysis was performed to identify predictors among the demographic variables, job characteristics, and socioeconomic factors between those who were stressed and not stressed using Wald test-statistics. Results were expressed as odds ratios using a 95% confidence interval. Multiple logistic regression models were used to identify significant independent predictors of job stress after adjusting for potentially confounding factors. Results were expressed as adjusted odds ratios with 95% confidence intervals. The final model was assessed using the Pearson chi-square goodness-of-fit test to see how well the model fit the data. Statistical significance was established when p < .05 (two-tailed). All statistical analyses were performed using SPSS (Statistical Package for Social Sciences version 20.0). Results: A total of 626 of the 1168 health care professionals completed the job stress and job satisfaction surveys, resulting in a response rate of 54%. Twenty-nine percent of the respondents were male, and 71.0% were female. The mean age among all participants was 39.3 years. Job Stress Results indicated that the majority of the health care professionals who participated reported moderate to high stress levels, and the overall prevalence of job stress was 66.2%. Results indicated that, on average, younger staff had higher stress levels than older staff (OR = 0.968; 95% CI: 0.95–0.987; p = .001). Residents reported a higher level of stress (p = .003). Being of Saudi nationality resulted in 4.4 times more stress than being non-Saudi (OR: 4.36; 95% CI: 2.46–7.73; p < .001) while education level did not result in a statistically significant relationship. Those who work more than 50 hours per week were more stressed (79.4%; p = .001). Of those who always worked night shifts, 84.0% were more stressed (p < .001), and of those who always worked weekends were also more stressed (81.8%’ p = .001) compared to those who never or sometimes worked weekends or nights shifts. Those who received free time compensation all the time were less stressed (56.8%) than those who received it sometimes (62.2%) or not at all (70.9%; p = .044).
Additionally, 93.9% of those who felt under pressure all the time, 95.2% of those who had conflicts of demand all the time, and 73.1% of those who believed there was inadequate staff to do the job were more stressed (p < .001 for all three groups). Health care professionals who don't know whom to approach if they have stress affecting their work and life were more stressed (76.3%; p < .001), and those who were exposed to a stressful event outside of work within a year were more stressed (73.8% p < .001). Those variables that were significantly associated with job stress using univariate analysis were considered for step-by step multiple logistic regression models to identify the statistically significant independent factors associated with job stress. These factors were: working on weekends, not getting free time compensation, feeling under pressure to meet deadlines, conflicts in the demand on time, being Saudi, believing there is inadequate staff to do the job, not knowing whom to approach if they are under stress, and being exposed to a stressful event outside of work within a year. Conclusion: This study shows that the current workplace environment could increase the risk of stress among health care professionals. However, the satisfaction rate was high and not negatively associated with low stress levels. The high satisfaction rate among the highly stressed could be a result of the benefits and incentive system applied in this organization. Our study identifies some potential factors, which if eliminated or changed, could lead to a decrease the stress level among health care workers. Future research is recommended to assess the impact of high stress on medical errors. This should be accompanied by studying the introduction of new policies and programs that could reduce the stress level among our health care staff.
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Attitudes, Barriers and Motivators of Clinical Research Recruitment in State of Qatar: Findings from PERCEPTIONS Study
المؤلفون: Hiba Tohid, Sahar Agouba, Lina Ahmed, Hoda Gad, Abdi Aden, Sopna Choudhury, Omar M. Omar, Odette Chagoury and Shahrad TaheriObjective: To explore the perceptions and attitudes about clinical research participation prevalent amongst the general public in State of Qatar. Background: Recruitment into research trials is a major challenge and an ongoing problem for biomedical researchers.1 A recent report indicates that only 6% of eligible subjects actually participate in a clinical trial.2 Costs of low recruitment rates are high. This includes not just loss of investment made in conducting the research but a more detrimental damage of investigator and institutional reputation as a result of a failed study.3 Surveys of attitudes to research participation have rarely been done.4 There is an urgent need to study and address recruitment shortfalls to ensure that trials meet their recruitment target.1
PERCEPTIONS Study (Perceptions about Enrollment and Recruitment in Clinical Research Prevalent In State of Qatar)
PERCEPTIONS Study is an elaborate, three phased, mixed design research project. Phase 1 was conducted to explore the existing attitudes and behaviours prevalent in the population in Qatar. With the dynamic National Vision 2030, Qatar is set to become world leader in health care research. Diabetes, hypertension, cancer and personalized medicine are some of the projected research goals therefore it is essential to gain an insight about the thoughts, beliefs and concerns of people that this research is meant to thrive with and eventually benefit. Methods: A survey was conducted at two large-scale public events held within the State of Qatar. Residents of Qatar who were 18 years of age or older were surveyed following a verbal consent. Those visiting/touring Qatar or under 18 years were excluded from the survey. Filled surveys were entered in Microsoft Excel and analyzed on SPSS version 23. Results: Total of 2517 surveys were conducted of which 2379 valid forms were analyzed. According to the data 5.6% respondents (n = 137) had previously been approached to participate in a clinical study. Of these 74.6% (n = 86) agreed to participate while 37.3% (n = 51) declined. Remaining 88.7% (n = 2114) of the surveyed population had never been approached to participate in a clinical study. Data was missing for 5.5% (n = 131) respondents. Main reasons for declined consent included: time constraint (50%, n = 11), ‘fear’ (13.6%, n = 3), lack of awareness about clinical research (9.1%, n = 2) and lack of interest in research (9.1%, n = 2). Maximum participation was reported in studies related to diabetes (n = 19) followed by heart diseases (n = 4). ‘To help others’ (n = 24) and ‘thought it might improve my access to health care’ (n = 21) were the prime motivators for participation. Maximum respondents (up to 50%) agreed that their research experience was associated with positive outcomes for self and others, research conduct was ethical and opportunities for participation were and will be welcomed. There was also significant disagreement that research had strong emotional repercussions or that the procedures were ‘too long’, ‘boring’ or ‘inconvenient’. Conclusion: Rate of clinical research participation in Qatar needs improvement. Out- reach to potentially eligible subjects is poor where an overwhelming majority is not approached for consent. Time constraints, lack of trust in and poor state of awareness about clinical research are main barriers to participation. Altruism, monetary benefits, improved health access are prime motivators. Length of stay in Qatar is a statistically significant determinant of recruitment in research (p < 0.002). Deeper insight into the factors affecting clinical research participation is needed to devise evidence based policies for improvement in recruitment strategies and the future of evidence based medical care.
Keywords: Attitudes, Barriers, Motivators, Clinical Research, State of Qatar
References: 1. Trauth JM, Musa D, Siminoff L, Jewell IK, Ricci E. Public attitudes regarding willingness to participate in medical research studies. J Health Soc Policy 2000;12(2):23–43.
2. Nair SC, Ibrahim H, Celentano DD. Clinical trials in the Middle East and North Africa (MENA) Region: grandstanding or grandeur? Contemp Clin Trials 2013 Nov;36(2):704–710.
3. McCullagh MC, Sanon MA, Cohen MA. Strategies to enhance participant recruitment and retention in research involving a community-based population. Appl Nurs Res 2014 Nov;27(4):249–253.
4. Teschke K, Marino S, Chu R, Tsui JK, Harris MA, Marion SA. Public opinions about participating in health research. Can J Public Health 2010 Mar-Apr;101(2):159–164.
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