QScience Connect - Volume 2012, Issue 1

Abstract The operational feasibility temperature range of chemical looping combustion (CLC) and chemical looping reforming (CLR) of the fuels methane, propane, iso-octane and ethanol was explored using the common sulphates Na 2SO 4, CaSO 4 and MgSO 4 as oxygen carriers. The chemical reaction equations for each oxygen carrier and fuel were formulated and fed into the Chemical Equations module of HSC Chemistry 5.1 soft Read More

Abstract Background: Organophosphorus compounds have important industrial and biomedical applications as pharmaceutical and agrochemical agents, as well as transition state analogs for the production of monoclonal antibodies. Methods: Two diastereomers of a 6-membered ring, cyclic phenyl phosphonate were synthesized in 8 steps from 1,3-butanediol. Results: The stereochemistry of the diastereomers was elucidated on the basis Read More

Abstract The study of phytoplankton diversity and its seasonal variation was carried out by sampling water taken from the Santragachi Lake, of West Bengal between November 2009 and July 2010. Various physico-chemical variables were recorded and the correlation of this with phytoplankton density was established using Canonical Correspondence Analysis. This showed that the density of phytoplankton was higher when temperature and Read More

Abstract The petroglyph site in Jabal Jassasiyah Qatar is located approximately 60 km northeast of the capital city of Doha and has over 900 different types of petroglyphs. The most commonly found petroglyphs are cupules, which are almost always arranged in geometric patterns. A number of petroglyphs of boats are also found, usually seen from above, with a few seen in profile. As there is little evidence of what age to assign to th Read More

Abstract Background: The incidence of oral indigenous bacteria in cases of bacteremia has been reported in only a few studies. We investigated the annual incidence of oral indigenous bacteria isolated in blood cultures from patients with bacteremia and call into consideration the impact of oral health measures implemented at our facility. Methods: In the period from 2001 to 2006, 759 laboratory-confirmed cases of bacteremia were report Read More

Background: Synthetic cationic lipids hold much potential as gene packaging and delivery agents for the treatment of inherited and acquired life threatening diseases, such as cancer, AIDS, cardiovascular diseases, and certain autoimmune disorders. Methods: We report the synthesis, self-assembly as characterized by critical micelle concentrations and plasmid DNA gel retardation using two novel cyclic, phosphonate cationic lipi Read More

Abstract The optimal conditions of liquid–liquid extraction of two synthetic phenolic antioxidants, BHA and BHT were investigated in five Iranian edible vegetable oil samples using the central composite design. Stepwise multiple linear regression method was used for construction of different models based on the experimental data. Optimum conditions for BHA and BHT were achieved using 3 ml of ethanolic solution containing (0.25% v/v) Read More

Abstract N,N-disubstituted bis(furanyl-2-methyl)aminoanilines are new electrochemically-active probes for cations relying on the phenylenediamine moiety as an electroactive transducer and the difuranylamino group as an ionophore site. The electrochemical investigations, by means of cyclic and Osteryoung square wave voltammetries (CV and SWV, respectively), showed that these compounds are able to bind Mg2+, Ca2+, Ni2+ and Read More

Abstract In this review, the story of Qatar’s economic emergence is told chronologically, beginning with Qatar’s independence and the discovery of the North Field gas reservoir in 1971 and ending with the steps that Qatar is now taking as it transitions towards a more diversified and innovative economy.

Abstract Background: Attempts to optimize the synthetic yield of known macrocyclic phosphonates resulted in the discovery of two new macrocyclic bisphosphonate dimers. Methods: An attempt was carried out to optimize the yield of a known macrocyclic bisphosphonate dimer, 6, over the yield of monomers 2 and 3, using the Mitsunobu protocol in the macrocyclization step. Cyclization reactions were carried out at 0.003 M, 0.004 M, 0.0 Read More

The inheritance mechanism for plant height, days to heading, spike length, grains spike− 1 and biological yield traits in 8 × 8 half diallel F2 wheat populations was studied at Agricultural University, Peshawar, Pakistan, during 2006-07. The experiment was laid out in randomized complete block (RCB) design having four replications. Each experimental unit was assigned a four-row plot of 5 m length with row-row space of 30 cm. Analyses of Read More

We present a geometric, model-independent, argument that aims to explain why the Tsallis entropy describes systems exhibiting “weak chaos”, namely systems whose underlying dynamics has vanishing largest Lyapunov exponent. Our argument relies on properties of a deformation map of the reals induced by the Tsallis entropy, and its conclusion agrees with all currently known results.