In this work an economical evaluation that established the viability of a low enthalpy geothermal resource as an energy source in north Africa is presented. The factors considered included the payback period, average ...In this work an economical evaluation that established the viability of a low enthalpy geothermal resource as an energy source in north Africa is presented. The factors considered included the payback period, average rate of return, net present value, and net benefit-cost ratio. The model was based on utilising the energy source to energise four models that comprised thermal equipment consisting of water/air cooled single/half effect lithium bromide water mixture absorption chillers and an R-245fa organic Rankine cycle. These modelled cycles were based on the energy demand for Waddan city a community in southern Libya which has a demand for combined cooling/electricity only or cooling/electricity with district hot water supply. The results revealed that all of the proposed simulated stand-alone models, except the water-cooled half effect chiller, are not economically viable unless they are heavily subsidized or combined with the district hot water supply at least in the winter season.展开更多
This study reports on the dietary exposure of people in Yaounde, Cameroon to heavy metals： lead （Pb）, cadmium （Cd）, mercury （Hg）, copper （Cu） and zinc （Zn）. One hundred and fifty table-ready food, water and...This study reports on the dietary exposure of people in Yaounde, Cameroon to heavy metals： lead （Pb）, cadmium （Cd）, mercury （Hg）, copper （Cu） and zinc （Zn）. One hundred and fifty table-ready food, water and soft drink samples were collected from households and street restaurants in Yaounde and analyzed for heavy metals contents using atomic absorption spectrophotometer. Lead （93%, range 0.019-1.77 ppm）, Cd （70%, range 0.01-4.68 ppm）, Hg （81%, range 0.03-10.56 ppm）, Cu （90%, range 0.004-40.32 ppm） and Zn （87%, range 0.014-2,447.04 ppm） were detected in studied samples. Maximum level of each metal exceeded its corresponding European Commissions legislative limits. Samples from street restaurants were most tainted with heavy metals. The highest average daily intakes （ADIs） of Pb （0.96 mg/day） and Hg （1.84 mg/day） were through tap water, while Cd （1.15 mg/day）, Cu （5.42 mg/day） and Zn （601.6 mg/day） were through rice/peanut sauce mixed food. The ADI for Cd and Hg was each higher than its respective PTDI （provisional tolerable daily intake） as defined by JECFA （Joint FAO/WHO Expert Committee on Food Additives） and EVM （Expert Group on Vitamins and Minerals）. The estimated average daily exposure dose of each detected metal significantly （p = 0.001） exceeded its corresponding PTDI. However, the health risk index was 〈 1 for all studied samples and it was found to be safe, indicating there is a relative absence of health risks associated with the ingestion of contaminated foods, water and soft drinks. Notwithstanding, the detected levels and ADI being higher than legislative limits and PTDI respectively speculates need for awareness raising towards reducing exposure levels to heavy metals in Cameroon.展开更多
Drug discovery is a costly and time-consuming process, with very few novel molecular entities approved for clinical use today. With the advancement of computational chemistry, integrated X-ray crystallography and nucl...Drug discovery is a costly and time-consuming process, with very few novel molecular entities approved for clinical use today. With the advancement of computational chemistry, integrated X-ray crystallography and nuclear magnetic resonance spectroscopy technology, more and more potential therapeutic agents for the treatment of human diseases are discovered. Furthermore, multiple medicinal chemistry approaches have been developed in support of early drug discovery. However, there is still much can be done in the early phase of drug discovery to improve the chances of success of a drug candidate. This paper reviews the discovery and evaluation of new chemical entities in the early stages of drug development.展开更多
A series of coumarin-derived azolyl ethanols including imidazolyl,triazolyl,tetrazolyl,benzotriazolyl,thiol-imidazolyl and thiol-triazolyl ones were conveniently synthesized and characterized by IR,~1H NMR,^(13)C NMR ...A series of coumarin-derived azolyl ethanols including imidazolyl,triazolyl,tetrazolyl,benzotriazolyl,thiol-imidazolyl and thiol-triazolyl ones were conveniently synthesized and characterized by IR,~1H NMR,^(13)C NMR and high-resolution mass spectra(HRMS) spectra.Some of the prepared compounds showed appropriate logP_(ow) values and effective antibacterial and antifungal activities.Noticeably,compound 14 with bis-triazolyl ethanol group exhibited low minimal inhibitory concentration(MIC)value of 8 μg/mL against MRSA,which was comparable or even superior to reference drugs Norfloxacin(MIC=8μg/mL)and Chloramphenicol(MIC=16μg/mL).It could also effectively inhibit the growth of the tested fungal strains compared to Fluconazole.Further binding studies of coumarin 14 with calf thymus DNA were investigated by UV-Vis absorption and fluorescence spectroscopy.It was found that compound 14 could interact with calf thymus DNA by groove binding to form14-DNA complex via both hydrogen bonds and van der Waals force,which might be the factor to exert the powerful antimicrobial activity.展开更多
文摘In this work an economical evaluation that established the viability of a low enthalpy geothermal resource as an energy source in north Africa is presented. The factors considered included the payback period, average rate of return, net present value, and net benefit-cost ratio. The model was based on utilising the energy source to energise four models that comprised thermal equipment consisting of water/air cooled single/half effect lithium bromide water mixture absorption chillers and an R-245fa organic Rankine cycle. These modelled cycles were based on the energy demand for Waddan city a community in southern Libya which has a demand for combined cooling/electricity only or cooling/electricity with district hot water supply. The results revealed that all of the proposed simulated stand-alone models, except the water-cooled half effect chiller, are not economically viable unless they are heavily subsidized or combined with the district hot water supply at least in the winter season.
文摘This study reports on the dietary exposure of people in Yaounde, Cameroon to heavy metals： lead （Pb）, cadmium （Cd）, mercury （Hg）, copper （Cu） and zinc （Zn）. One hundred and fifty table-ready food, water and soft drink samples were collected from households and street restaurants in Yaounde and analyzed for heavy metals contents using atomic absorption spectrophotometer. Lead （93%, range 0.019-1.77 ppm）, Cd （70%, range 0.01-4.68 ppm）, Hg （81%, range 0.03-10.56 ppm）, Cu （90%, range 0.004-40.32 ppm） and Zn （87%, range 0.014-2,447.04 ppm） were detected in studied samples. Maximum level of each metal exceeded its corresponding European Commissions legislative limits. Samples from street restaurants were most tainted with heavy metals. The highest average daily intakes （ADIs） of Pb （0.96 mg/day） and Hg （1.84 mg/day） were through tap water, while Cd （1.15 mg/day）, Cu （5.42 mg/day） and Zn （601.6 mg/day） were through rice/peanut sauce mixed food. The ADI for Cd and Hg was each higher than its respective PTDI （provisional tolerable daily intake） as defined by JECFA （Joint FAO/WHO Expert Committee on Food Additives） and EVM （Expert Group on Vitamins and Minerals）. The estimated average daily exposure dose of each detected metal significantly （p = 0.001） exceeded its corresponding PTDI. However, the health risk index was 〈 1 for all studied samples and it was found to be safe, indicating there is a relative absence of health risks associated with the ingestion of contaminated foods, water and soft drinks. Notwithstanding, the detected levels and ADI being higher than legislative limits and PTDI respectively speculates need for awareness raising towards reducing exposure levels to heavy metals in Cameroon.
基金The Shanghai Committee of Science and Technology (Grant No.11DZ2260600)the Fundamental Research Funds for the Central Universities
文摘Drug discovery is a costly and time-consuming process, with very few novel molecular entities approved for clinical use today. With the advancement of computational chemistry, integrated X-ray crystallography and nuclear magnetic resonance spectroscopy technology, more and more potential therapeutic agents for the treatment of human diseases are discovered. Furthermore, multiple medicinal chemistry approaches have been developed in support of early drug discovery. However, there is still much can be done in the early phase of drug discovery to improve the chances of success of a drug candidate. This paper reviews the discovery and evaluation of new chemical entities in the early stages of drug development.
基金supported by the National Natural Science Foundation of China(21172181,21372186,81450110094, 81250110089,81350110338)the Key Program from Natural Science Foundation of Chongqing(CSTC2012jjB10026)the Specialized Research Fund for the Doctoral Program of Higher Education of China(SRFDP 20110182110007)
文摘A series of coumarin-derived azolyl ethanols including imidazolyl,triazolyl,tetrazolyl,benzotriazolyl,thiol-imidazolyl and thiol-triazolyl ones were conveniently synthesized and characterized by IR,~1H NMR,^(13)C NMR and high-resolution mass spectra(HRMS) spectra.Some of the prepared compounds showed appropriate logP_(ow) values and effective antibacterial and antifungal activities.Noticeably,compound 14 with bis-triazolyl ethanol group exhibited low minimal inhibitory concentration(MIC)value of 8 μg/mL against MRSA,which was comparable or even superior to reference drugs Norfloxacin(MIC=8μg/mL)and Chloramphenicol(MIC=16μg/mL).It could also effectively inhibit the growth of the tested fungal strains compared to Fluconazole.Further binding studies of coumarin 14 with calf thymus DNA were investigated by UV-Vis absorption and fluorescence spectroscopy.It was found that compound 14 could interact with calf thymus DNA by groove binding to form14-DNA complex via both hydrogen bonds and van der Waals force,which might be the factor to exert the powerful antimicrobial activity.
