Qatar Foundation Annual Research Conference Proceedings Volume 2018 Issue 1

The constant increase in energy demand necessitates exploration of new oil fields at challenging reservoir environments. A proper selection of the drilling fluid, or a drilling mud, is crucial in minimizing the cost and time required for the drilling process. The circulating drilling fluid aids in cooling, lubricating the drilling bit and in removing the rock cuttings from the drilling well. Water-based muds are widely used as a drilling fluid in oil and gas industry while exploring the hydrocarbon. During deep-sea drilling activities at extreme depths, high-temperature and high-pressure (HTHP) conditions are encountered. These results in overheating of drilling equipment and malfunction due to lost circulation posing a severe limitation to the drilling fluid used. Several studies have been conducted to enhance the rheological and thermal properties of water-based drilling muds. Owing to the enhanced thermo-physical properties and stable nature, suspensions of nanoparticles have been suggested to be used along with drilling fluids for such conditions. Colloidal suspensions containing nano-sized particles (1-100nm) in a basefluid are generally termed nanofluids. Rheological characteristics of various nanofluids prepared from different types of nanoparticles have been thoroughly studied in the past. However, the effect of nanoparticles on drilling fluids at high temperature and pressure conditions are not investigated in detail. In the present work, the rheological study of nanomud suspensions prepared by adding multi-walled carbon nanotubes (MWCNT) into the drilling fluid is conducted. A Nanofluid suspension based on CNT is deemed advantageous due to its high thermal conductivity, and efficient mechanical properties. High-pressure and high-temperature rheology of a nanomud suspension is reported here. The CNT-drilling mud nanofluids (nanomuds) are prepared using a top-down approach. Initially, the water-based drilling mud (base fluid/basemud) is prepared. The Water Based Mud (WBM) used in this study contain Bentonite (1%) and Barite (7%) which makes up the total percentage of solids by volume of the whole mud with a 12.5 ppg (pounds per gallon) as the final weight. The Bentonite was initially mixed with the water and seated for approximately 16 hours of hydration to form Prehydrated Bentonite or PHB. A high-pressure high-temperature (HPHT) viscometer (Chandler Viscometer 7600) is used for the rheological analysis. The viscometer is designed for rheological studies of drilling fluids while subjected to varying drilling well conditions in accordance with ISO 10414-1, 10414-2 and API 13 recommended practices. As the variation of the pressure and temperature would influence the measured viscosity values of the suspension, two independent experimental schedules are performed. Automated measurements are recorded once the pressure and temperature values of the sample have reached the set values. Viscosity values are measured at a maximum pressure of 170 MPa with temperatures ranging from ambient to 180°C. The effect of MWCNT nanoparticle concentration and variation in shear rate are also investigated. A shear thinning non-Newtonian behavior is observed for the basemud and the nanomud samples at all pressures and temperatures. The basemud showed an increase in viscosity with an increase in pressure. However, with MWCNT particle addition, this trend is observed to have reversed.

Modeling the diffusion of residential solar photovoltaic (PV) systems in their social, political and economic context is crucial to help policymakers assess which policies may best support adoption. Current models of renewable energy adoption [1, 2, 3, 4] assume regulatory and incentive frameworks that do not apply to Gulf Cooperation Council (GCC) states, where energy tariffs are strongly subsidized, tax credits are not viable due to the lack of personal income tax, and support for distributed generation through grid access policies such as the Feed-in Tariff and Net Metering is not available. The goal of this study is to address this gap by analyzing the impact of home ownership, the falling cost of PV, the reduction of electricity subsidies, the introduction of a carbon tax, and the diffusion of innovation on the residential adoption of solar PV technologies in Qatar. Our objective is to develop a social simulation platform that helps policymakers and other stakeholders assess the optimal regulatory framework to promote the adoption of building-integrated PV systems in Qatar and other countries which share a similar geographical, political, economic and social context. We present an agent-based model for residential adoption of solar photovoltaic (PV) systems in the state of Qatar as a case study for the Arabian Gulf Region. Agents in the model are defined as households. Each household corresponds to a dwelling in the Al Rayyan municipality of Qatar that is either owned (by citizens) or rented (by expatriates). The objective of the model is to evaluate PV adoption in terms of these two household cohorts under diverse regulatory and incentive scenarios. In the present state of affairs, only Qatari citizens can own property in Al Rayyan and Qatari households are exempt from electricity charges. Therefore, home owners are Qataris who have free electricity, while renters tend to be expatriates who pay for electricity. The more competitive the cost of electricity from residential PV systems is as compared to the electricity tariff, the more likely are household agents to adopt solar PV. Several factors can contribute to make the cost of electricity from residential PV more competitive, including: the falling cost of PV due to increasing technology maturity the reduction of subsidies for electricity and the gas used for electricity production the introduction of a carbon tax the extension of the electricity tariff to Qatari households the neighborhood effect, which implements peer effects on the diffusion of PV innovation as a percent discount on residential PV cost. We compute solar PV adoption as resource limited exponential growth. Households adopt solar PV with a probability established by the logistic function in (1), where L is a scaling constant, e is the natural logarithm, x is the cost of electricity from residential PV systems and k is a parameter which determines the slope of the adoption curve. We set L = 1 to normalize the output of the logistic function as a probability. For the k parameter, we select a value (k = 0.59) that in the null-hypothesis scenario yields a PV market share that is equivalent to the innovator cohort of adopters in Rogers' adoption/innovation curve (2.5%) [5]. According to Rogers, “innovators are active information seekers about new ideas”, who are close to the scientific community and other innovators, have financial liquidity, and are willing to take high risks to pursue their vision. The rationale for restricting adopters to innovators in the null hypothesis scenario is that only eco-warriors with financial means and high technology awareness would adopt in the absence of incentives, with high PV costs.(1) f (x) = L / 1 + e^(-k*x) At each simulation tick, each household agent that has not adopted yet, is presented with the opportunity of doing so. Adoption is determined randomly according to the output of the logistic function in (2): a random probability p is generated, and if the probability of adoption as calculated by (1) is greater or equal to p, adoption occurs. We analyze three alternative simulation scenarios: Scenario 1 – Business as usual: no measures are introduced to incentivize PV, the neighborhood effect is active, and the price of PV falls due to increasing technology maturity Scenario 2 – 40% of gas and electricity subsidies are curtailed, the neighborhood effect is active, a carbon tax of $8/tCO2e is introduced, the price of PV falls due to increasing technology maturity, and citizens continue to have free electricity Scenario 3 – same as scenario 2, with the variant that citizens to pay for electricity. As baseline, we establish a null hypothesis scenario, which is the same as scenario 1, except that the price of PV does not fall due to increasing technology maturity. Details of the simulation results are provided in the attached file to this submission. Our study suggests that Qatar's residential PV adoption is strongly promoted by the falling cost of PV and can be further facilitated through the reduction of electricity subsidies and the extension of the electricity tariff to Qatari households, which are currently exempt. The introduction of a carbon tax can also play a role in accelerating residential PV adoption, if above $8 per metric ton of carbon dioxide equivalent. The ensuing PV adoption rates would help facilitate the national targets of 2% electricity production from solar energy by 2020 and 20% by 2030.

References

[1] Zhao, J., E. Mazhari, N. Celik, Y.-J. Son. “Hybrid agent-based simulation for policy evaluation of solar power generation systems”. Simulation Modeling Practice and Theory 19, (2011): 2189‒2205.

[2] Paidipati, J., L. Frantzis, H. Sawyer, A. Kurrasch. “Rooftop photovoltaics market penetration scenarios”. Navigant Consulting, Inc., for NREL: February, (2008).

[3] Drury, E., P. Denholm, R. Margolis. “Modeling the US rooftop photo- voltaics market”. In National Solar Conference 2010, 17‒22 May 2010, Phoenix, USA, (2010).

[4] Graziano, M. and K. Gillingham. “Spatial patterns of solar photovoltaic system adoption: the influence of neighbors and the built environment”. Journal of Economic Geography 15, (2015): 815‒839.

[5] Rogers, E. M. Diffusion of innovations. New York, Free Press of Glencoe, RS(N), (2010).

Soluble conjugated polymers have nowadays attracted broad academic and industrial spotlight as innovative materials of easy tuneable optical and electronic properties.1 These properties translate into various optoelectronic applications such as organic solar cells, light-emitting diodes (LEDs), and thin film transistors. The pivotal parameters that define characteristics of conjugated polymer based devices are of chemical (structure, solubility, mass) and mechanical (macroscopic) nature.2 Although the physical properties CPs is determined by designed chemical structure, critical alterations result from variations of the nanostructure of the polymer in its solid state.3 Therefore the complete optoelectronic potential of CP based device can be fully assessed only with the optimal conjugated chains alignment. We envisioned thermal and UV induced post processing of conjugated polymers predesigned to dramatically change their properties in given conditions by removal of nonconductive side chains and reducing interlayer distance.

About one third of the oil and gas extracted worldwide comes from offshore sources. There is currently thousands of large-scale oil and gas platforms spread across the seas and coastal oceans, from the North Sea to the seas of South Asia. Although their primary purpose is not related to enrichment of biodiversity, gas and oil platforms can act as large and complex artificial marine habitats for a wide range of marine organisms, including sessile invertebrates and fishes. These structures have shown to enhance ecosystem function, especially secondary fish production, relative to adjacent natural reefs, besides being among the most productive marine fish habitats globally. Indeed oil platforms constitute important fish aggregating devices, especially in areas subjected to a range of environmental perturbations. Hard substratum availability combined with exclusion zones around these structures allows for the development of diverse fish assemblages. We carried out the first assessment of vertical distribution, diel migration, taxonomic and functional diversity of fishes at offshore platforms in the Arabian Gulf. Video footages were recorded at the Al Shaheen Oil Field, between 2007 and 2014 using a Remotely Operated Vehicle (ROV). Indeed diving and snorkeling are strictly forbidden in the exclusion zone around offshore platforms, precluding conventional monitoring techniques such as underwater visual census, collection of sessile organisms, etc. Routine inspection and maintenance surveys, however, are conducted to monitor the state of underwater structures using ROVs. A total of 4,510 video files, containing 120 hours of underwater video recordings, were provided by Maersk Oil Qatar A/S. These videos were recorded over six years (2007, 2009, 2010, 2011, 2012 and 2014), during day and night, at the 9 platform locations (A-I) within the Al Shaheen Oil Field using a ROV of the model SAAB Seaeye Surveyor Plus 229. To assess the local fish community, a total of 242 videos amounting to twenty-one hours of observation were selected randomly, however, if no fish appear in a selected video a new video was randomly selected from the list. This work represents the first assessment of reef fish communities inhabiting oil and gas platforms in the Arabian Gulf. A total of 12,822 fish, belonging to 83 taxonomic groups were recorded around the platforms. Among them, two species are first recorded for Qatari waters: Cyclichthys orbicularis and Lutjanus indicus. In addition two chondrichthyes, one endangered (Stegostoma fasciatum) and a vulnerable species (Taeniurops meyeni), were also observed across the platforms. Several trends were found in the vertical distribution of the fish community, most species were observed between 20 and 50 m depth and higher fish abundance recorded in the upper layers, down to 40 m depth and decreasing with depth. Vertical variation, however, in fish diversity was generally not accompanied by differences in vertical movements. The vertical variation, however, in fish diversity was not accompanied by differences in vertical movements of the fish. These results suggest that the vertical zonation pattern does not change, or only changes slightly, on a daily basis. The mean centers of mass of the most abundant fish species did not overlap, likely due to potential competition or niche differences. The dominant trophic groups were carnivores and invertivores, being well represented at each depth range (each spanning 10 m) from surface to seabed. Diel vertical movement was observed only for Acanthopagrus bifasciatus, which was concentrated at shallow depths during the daytime but migrated to deeper layers at night. The functional indices showed no significant differences between water depths or diel cycles (day / night). Besides the temperature variation, the reduced light penetration due to platform structures makes difficult the algal growth necessary for browsing herbivorous fish. Thereby, the effect of sunlight penetration may be reflected in the vertical distribution of herbivorous fish, which are rare in deeper layers. Planktivores are densely grouped within and just below the thermocline, which is located around 18 m during summertime. The study demonstrates that oil platforms represent a hotspot of fish diversity and interesting sites for studying fish communities, abundance and behaviour.

Designing Photo Absorbing Materials by Cation Substitutions for Photovoltaics Merid Legesse1, Heesoo Park1, Fedwa El Mellouhi1, Sergey N Rashkeev1, Sabre Kais1, 2, 3, Fahhad H Alharbi1, 3 1Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha, Qatar. 2Department of Chemistry and Physics, Purdue University, West Lafayette, Indiana 46323, USA. 3College of Science and Engineering, Hamad Bin Khalifa University, Doha, Qatar. Email: [email protected]. Recently, significant research efforts have focused on some emerging solar cell technologies such as dye-sensitized solar cells, perovskite photovoltaics, etc. However, these technologies face many challenges. In this talk, we will present a new family of light absorbing materials so-called pyroxene silicates. These materials are abundantly present in the earth crust however, bandgaps of naturally formed pyroxene silicates such as NaAlSi2O6 are quite high (∼5 eV). Therefore, it is important to find a way to reduce bandgaps below 3 eV to make them usable for optoelectronic applications [1, 2, 3]. Using first-principles calculations we investigated the possibility of band structure engineering of pyroxene silicates with chemical formula A+1B+3Si2O6 by proper cation substitution (A+ =  Na, NH4+, PH4+, SH3+, CH3NH3+, CH3PH3+, CH3SH2+ and B3+ =  Al3+ Ga3+, In3+, Tl3+). We found that appropriate substitutions of both A+ and B3+ cations can reduce the bandgaps of these materials to as low as 1.31 eV. In this talk, we will also discuss in details how the bandgap in this class of materials is affected and thermodynamic stabilities. We would like to thank Qatar National Research Foundation (QNRF) for the support (Grant No. NPRP 7-317-1-055. References (1) A.A.B. Baloch, S.P. Aly, M.I. Hossain, F. El-Mellouhi, N. Tabet, and F.H. Alharbi, Sci. Rep. 7, 11984 (2017). (2) F. El Mellouhi, A. Akande, C. Motta, S.N. Rashkeev, G. Berdiyorov, M.E.A. Madjet, A. Marzouk, E.T. Bentria, S. Sanvito, S. Kais, and F.H. Alharbi, ChemSusChem 10 1931 (2017). (3) F.H. Alharbi, S.N. Rashkeev, F. El-Mellouhi, H. P. Lüthi, N. Tabet, S. Kais, npj Comput. Mater 1, 15003 (2015).

Drilling phase is one of the most important parts of developing a field. The durability of the well and its performance is greatly related to the quality of the drilling. A good drilling will also have an effect on how fast the project can start make profits as the drilling phase become shorter and more efficient. There are number of different factors that can hinder the quality of the drilling job and in some cases stop it or damage the wellbore and cause catastrophic disasters. Barite sagging is a one of the main causes of damage in the wellbore during the drilling stage. Any drilling job needs a drilling fluid that can provide the engineers with: enough hydrostatic pressure to prevent the well from collapsing in, removing the drilling cuts to the surface, cools down and lubricates the drill bit during the drilling job, suspend the drilling cuts within itself during the drilling and when drilling is stopped,seal the permeable zones in the wellbore to prevent lost circulation, control the corrosion caused by corrosive gasses such as H2S, provide hydraulic energy to the bit to fasten and improve the drilling and finally help the engineer to the cementing and completion after the drilling was done. Barite Sag is a common phenomenon that occurs while drilling for oil and gas. Barite, BaSO4 is a weighing agent used to increase the density of drilling fluids to a desired level. It has a high density of 4.2 g/cm3. The problem that occurs in this phenomenon is that as the mud is circulated through the borehole, the barite that was dissolved in the mud starts separating from the liquid phase and settles down. This separation of barite from the aqueous phase creates an undesired density gradient and causes a lot of further problems. Barite sag can occur in both conventional and deviated wells. In vertical wells, higher density drilling fluids or barite-rich phase settles on the bottom of the well bore while the lower density fluid form layers on the upper part of the column. This usually occurs during static conditions i.e. when drilling is stopped or very low shear rate (rpm). Additionally, a very low shear-rate viscosity can also result in barite sag. However, deviated wells are more susceptible to barite sag as in deviated wells, gravity induces an additional settling effect which results in sediment beds of barite at the bottom of the borehole. In deviated wells, Boycott effect is the reason for barite sagging. In an inclined tubing, the vertical distance of the settling particles is greatly reduced as compared to that in vertical columns. Hence the process of sedimentation is accelerated. Barite sagging can cause some serious problems during drilling operations. These problems are: loss of mud circulation, well bore instability, and uneven mechanical friction which can cause pipes and tools to get stuck downhole. Barite sagging, if not controlled properly, can lead to a complete shutdown and well abandonment. Hence, this study is being conducted to look in detail at the various chemical and physical factors, that affect barite sag, so that more viable and optimal solutions can be derived to control the extent of barite sag. Barite sagging is just a general term used to describe the phenomenon of which the weighting material detaches itself from its own liquid phase and slowly settles down the wellbore. But many more specific examples of barite sagging have been looked into and researched to further expand our understanding of this phenomenon. From dynamic to static sagging, in wells that are vertical, horizontal or deviated, all of these scenarios have been heavily examined and studied. The extent of the research that has been done in regards to barite sagging is surely well deserved as barite sagging can cause major problems while drilling in the field such as loss circulation, sudden changes of density in the drilling fluid which could further escalate into a blowout. Problems with cementation, well control issues and stuck pipe, all have been encountered mainly due to barite sagging. The research papers available look into a wide range of aspects related to barite sagging, but I will mainly look at the research conducted that studies adding different substances into the drilling fluids and comparing the effects that the new substances can cause to the sagging affect. Another major topic that I will try to cover is the different methods that have been used through the years to measure barite sagging in the laboratory environments.

Alessandro Sinopoli, a Michael Wasielewski, b Muhammad Sohail. a aQatar Environment & Energy Research Institute, Hamad Bin Khalifa University, PO Box 5825, Doha, Qatar; bDepartment of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA. The use of fossil fuels, especially natural gas, which has a lower carbon burden than oil or coal, will continue to dominate the energy market for the next several decades. In order to mitigate the large amounts of CO2 released into the atmosphere, it is essential to have clean ways of converting the CO2 back into a high energy density liquid fuel. Benchmark catalysts for CO2 reduction typically employ second and third row transition metals like palladium, iridium, and rhenium. The rarity, cost, and environmental ramifications of mining large quantities of such precious metals deter scaling up the usage of such catalysts. Developing a CO2 catalytic system that uses earth abundant first row transition metals like manganese, will push the field away from rare earth metal catalysts. While still an emerging field, transition metal-based catalysts can be successfully integrated in electrochemical and photoelectrochemical devices for CO2 reduction. Inside this class of compounds, developing manganese-based systems remains an extremely promising strategy for the advent of low cost but at the same time efficient molecular systems for CO2 reduction. We will therefore investigate Mn(bpy)(CO)3Br and its related derivatives that have recently been shown to efficiently reduce CO2 to CO. More importantly, none of these Mn-bipyridine complexes have yet been integrated with a covalent photo-driven source of electrons and this will be the main synthetic and experimental challenge within this project. Aromatic organic anions (radical anions or closed shell dianions) are reactive species involved in various chemical transformations. The photochemistry and photophysics of these species have been the subject of extensive study since they have been implicated in many photo-induced electron transfer processes, and are suggested to be powerful reducing agents. Such properties were substantiated by the observation of rapid electron ejection to give solvated electrons, electron-cation pairs, or reduced electron acceptors upon photolysis of aromatic anions (e.g. sodium pyrenide or biphenylide). We envision that the high reducing power (up to − 3 V vs. SCE) of excited monoanions or dianions of aromatic diimides can be exploited for CO2 reduction catalysis. In particular, the anions of PDI perylene-3,4:9,10-bis(dicarboximide) and its homolog naphthalene-1,8:4,5-bis(dicarboximide) (NDI) will be used as the primary photosensitizers in this study. These planar, chemically robust, redox-active compounds are widely used as industrial pigments, supramolecular building blocks, photooxidants, and n-type semiconducting materials. In the effort of integrating NDI and PDI units in the design and development of manganese based photocatalysts, experiments will be carried out in two stages. In the first stage, we will synthesise photosensitizer systems designed specifically to act as catalysts, so that their structures and properties can be determined. Figure 1. Examples of Mn-based catalysts designed for this project. The structures depicted in Figure 1 are examples of PDI and NDI photosensitizer systems designed for this project. For example, in the molecule on the left (Figure 1), two easily reducible PDI molecules are covalently attached to the bpy ligand. One-electron reduction of PDI will produce the stable PDI-• radical anion. The structure of the designed manganese complexes, the dynamics of CO2 binding, and subsequent protonation of the bound Mn carboxylate will be studied using femtosecond transient absorption spectroscopies with both UV-Vis and mid-IR probing as well as and femtosecond stimulated Raman spectroscopy (FSRS). The second stage of the experiments will study the laser-generated Mn(0)(bpy)-1(CO)3-based catalyst followed by CO2 binding and protonation. For this we will perform steady-state photolysis experiments on the systems in DMF with varying amounts of HBF4 and CO2 up to the limit of a saturated solution of CO2 in DMF at 25 °C and 1 atm, which is about 0.14 M. These studies will look for products generated following one-electron reduction of the Mn catalysts. We will quantitate the yield of CO produced by the overall photoreaction using a 16-sample parallel system in which the samples are illuminated using filtered LEDs and a parallel, continuous gas sampling system connected to a gas chromatograph. The system will be calibrated with appropriate standard gas mixtures, and a full range of conditions and appropriate control experiments will be performed by varying the concentrations of catalyst, CO2, HBF4, and sodium ascorbate in the solution. Solar energy, an abundant resource in Qatar, can drive CO2 reduction to produce both liquid solar fuels and potentially high value chemicals. In this regard, our study will represent the birth of a new generation of efficient photocatalytic systems for CO2 reduction by coupling robust light harvesting molecules with earth abundant transition metals like manganese.

The development of nanoscience and technology has devoted significant attention to conducting studies on hollow particles. Among the available materials, mesoporous silica nanoparticles have recently gained attention as potential nanocontainers due to their high stability, large surface area, controllable pore diameter and easy surface functionalization as they can store and release organic or inorganic molecules of different sizes and functionalities. The aim of this work is to study the use of mesoporous silica as a potential reservoir for corrosion inhibitor for active corrosion protection of carbon steel and using epoxy encapsulated halloysite nanotubes for the self healing process of the epoxy based coatings. The synthesized mesoporous silica particles were characterized by using XRD, FTIR and SEM. Mesoporous silica particles loaded with diethylenetriamine (DETA) were embedded into the epoxy polymer along with the halloysite nanotubes (HNTs) encapsulated with epoxy monomer and amine immobilized in mesoporous silica with a weight ratio of 5 wt% of mesoporous silica. Kinetics of release of corrosion inhibitor was evaluated by electrochemical impedance (EIS) measurements in 3.5 wt% NaCl solution. The EIS analysis confirms that the release of inhibitor during the corrosion process has significantly improved the anticorrosion properties when compared to the epoxy coated sample without any corrosion inhibitor. The self healing phenomenon in the scratched epoxy coated sample was monitored by SEM during different time intervals. The SEM results showed that that the epoxy pre-polymer was slowly released into the crack.Upon release, the epoxy pre-polymer came into contact with the amine immobilized in mesoporous silica and cross-linked to heal the scratch over the sample surface. This study suggests that these novel coatings may have some potential applications in the oil and gas industry.

Thermal Hysteresis of Palladium encaged inside Mesoporous Silica catalyst for Low Temperature CO oxidation Rola Al Soubaihi 1,2, Joydeep Dutta2 Liberal Arts and Science Program, Virginia Commonwealth University-Qatar, Doha, Qatar Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden Carbon Monoxide (CO) is colorless, odorless gas produced from incomplete combustion of carbon fuel under conditions with a limited supply of oxygen. Catalytic oxidation is one of the effective methods of removing CO and convert it to CO2. [1] Catalyzed CO oxidation reaction finds applications in many fields such as environmental protection, air purification for buildings or cars, orbiting, closed-cycle CO2 lasers, gas masks for mining applications, CO detectors[2-3]. Depending on their size, shape, and preparation conditions, Nanocatalysts can exhibit unique properties (electrical, optical, magnetic, and catalytic) which are different from their bulk material properties [4-6]. The surface of nanomaterials contains large number of high energy defects such as surface and edge atoms that can provide active sites for catalyzing surface reactions by lowering the activation energy [7-8]. Supported Palladium catalysts are known for their high activity, recyclability, and their cheap cost when compared to platinum catalysts. Support plays a crucial role in the synthesis of such catalysts. In this regard support can reduce the amounts of the metal and ensure a good dispersion, and increase their thermal stability. Mesoporous materials with large internal surface areas (>1000 m2/g) and narrow pore size distributions can be an ideal support for Palladium based catalysts [9-10]. Silica are well known for structural and thermal properties and allow anchoring of catalytically palladium active species onto their surfaces. Silica can provide enormous beneficial features to enhance the catalytic activity such as high surface area, high porous, high thermal insulation, and local heating and heat retention [11-13]. Here, we report for the first time exceptional catalytic CO oxidation on Pd supported on mesoporous SiO2 with good stability and recycling behavior under heating and cooling conditions with wide CO Thermal hysteresis (close to 200 °C). We attribute our results to the phase transformation of Palladium to palladium oxide intermediate at different temperatures during the heating and cooling cycles and the structure and the local environment of the palladium since Pd clusters are small and highly dispersed on the silica surfaces and encaged inside the pores. References [1] S. Biswas, K. Mullick, S. Y. Chen, A. Gudz, D. M. Carr, C. Mendoza, et al., «Facile access to versatile functional groups from alcohol by single multifunctional reusable catalyst,» Applied Catalysis B-Environmental, vol. 203, pp. 607–614, Apr 2017. [2] X. Zhang, Zhenping Qu, Xinyong Li, Meng Wen, Xie Quan, Ding Ma, and Jingjing Wu., «Studies of silver species for low-temperature CO oxidation on Ag/SiO 2 catalysts.,» Separation and Purification Technology, vol. 3, pp. 395–400., 2010. [3] P. A. Wright, Srinivasan Natarajan, John M. Thomas, and Pratibha L. Gai-Boyes, «Mixed-metal amorphous and spinel phase oxidation catalysts: characterization by x-ray diffraction, x-ray absorption, electron microscopy, and catalytic studies of systems containing copper, cobalt, and manganese,» Chemistry of materials vol. 5 pp. 1053–1065., 1992. [4] A. Cubo, J. Iglesias, G. Morales, J. A. Melero, J. Moreno, and R. Sanchez-Vazquez, «Dehydration of sorbitol to isosorbide in melted phase with propyl-sulfonic functionalized SBA-15: Influence of catalyst hydrophobization,» Applied Catalysis a-General, vol. 531, pp. 151–160, Feb 2017. [5] W. Fang, Y. C. Deng, L. Tang, G. M. Zeng, Y. Y. Zhou, X. Xie, et al., «Synthesis of Pd/Au bimetallic nanoparticle-loaded ultrathin graphitic carbon nitride nanosheets for highly efficient catalytic reduction of p-nitrophenol,» Journal of Colloid and Interface Science, vol. 490, pp. 834–843, Mar 2017. [6] M. V. D. Fernandes and L. R. D. da Silva, «Structural analysis of mesoporous vermiculite modified with lanthanum,» Materials Letters, vol. 189, pp. 225–228, Feb 2017. [7] A. K. Herrmann, P. Formanek, L. Borchardt, M. Klose, L. Giebeler, J. Eckert, et al., «Multimetallic Aerogels by Template-Free Self-Assembly of Au, Ag, Pt, and Pd Nanoparticles,» Chemistry of Materials, vol. 26, pp. 1074–1083, Jan 2014. [8] R. Muller, S. H. Zhang, B. Neumann, M. Baumer, and S. Vasenkov, «Study of Carbon Dioxide Transport in a Samaria Aerogel Catalyst by High Field Diffusion NMR,» Chemie Ingenieur Technik, vol. 85, pp. 1749–1754, Nov 2013. [9] Al-Oweini, S. Aghyarian, and H. El-Rassy, «Immobilized polyoxometalates onto mesoporous organically-modified silica aerogels as selective heterogeneous catalysts of anthracene oxidation,» Journal of Sol-Gel Science and Technology, vol. 61, pp. 541–550, Mar 2012. [10] B. N. Bhadra, P. W. Seo, J. W. Jun, J. H. Jeong, T. W. Kim, C. U. Kim, et al., «Syntheses of SSZ-39 and mordenite zeolites with N,N-dialkyl-2,6-dimethyl-piperidinium hydroxide/iodides: Phase-selective syntheses with anions,» Microporous and Mesoporous Materials, vol. 235, pp. 135–142, Nov 2016. [11] S. Dilger, C. Hintze, M. Krumm, C. Lizandara-Pueyo, S. Deeb, S. Proch, et al., «Gas phase synthesis of titania with aerogel character and its application as a support in oxidation catalysis,» Journal of Materials Chemistry, vol. 20, pp. 10032–10040, 2010. [12] A. K. Herrmann, P. Formanek, L. Borchardt, M. Klose, L. Giebeler, J. Eckert, et al., «Multimetallic Aerogels by Template-Free Self-Assembly of Au, Ag, Pt, and Pd Nanoparticles,» Chemistry of Materials, vol. 26, pp. 1074–1083, Jan 2014. [13] R. Muller, S. H. Zhang, B. Neumann, M. Baumer, and S. Vasenkov, «Study of Carbon Dioxide Transport in a Samaria Aerogel Catalyst by High Field Diffusion NMR,» Chemie Ingenieur Technik, vol. 85, pp. 1749–1754, Nov 2013.

Food handling practices (FHP) is one of the most important stage where microbes can be introduced into produce through the infected food handlers or by cross-contamination. The fresh produce market in Doha, Qatar is the major market from which most of the food businesses, restaurants, super markets, and consumers obtain their fresh produce. Produce is handled by workers with no or minimum knowledge on safe produce handling practices. This study was carried out to assess the food safety knowledge and self-reported handling practices applied by produce handlers working at this major produce market in Qatar. About 120 produce handlers were surveyed using a systematic questionnaire (No. QU-IRB 509-E/15) to determine their food safety knowledge and attitudes during handling of fresh produce in January 2016. In addition, hand-swab samples and work uniform photos were collected. A standard microbial count were applied on the collected swabs to determine the hands' hygiene levels of the workers. The identification of microorganisms isolated from their hand swabs was carried out using MALDI-TOFF. The survey results revealed that the hygiene practices and food safety knowledge among produce handlers working at this produce market are insufficient. It was determined that none of the handlers received any food safety training on safe produce handling practices before joining the work at the market. Most of the workers' age was below 50 yrs (82.5%), about 37% of them was between 31 and 40 years old. Regarding educational level; 57.5% of them had middle school degree or below. More than 60 % of them claimed to wash their hands 4–5 times per duty time. The microbial hand-swabbing analyses demonstrated the presence of Enterococcus faecium, Klebsiella pneumoniae, Staphylococcus spp., and Bacillus circulans. Overall, these results are significant because they highlight the need to promote additional efforts that might assist in developing necessary intervention strategies to improve the conditions at this major market and prevent future foodborne illness outbreaks linked to produce sold in Qatar.