新能源产业的飞速发展使磷酸铁锂电池广泛应用于储能领域。磷酸铁锂电池电解液固有的可燃性使其热稳定性和安全性问题不容忽视。为了更好地防控储能电站的爆炸事故,有必要开展储能电池的热失控过程研究,并对产气过程和产气组分的危害性...新能源产业的飞速发展使磷酸铁锂电池广泛应用于储能领域。磷酸铁锂电池电解液固有的可燃性使其热稳定性和安全性问题不容忽视。为了更好地防控储能电站的爆炸事故,有必要开展储能电池的热失控过程研究,并对产气过程和产气组分的危害性进行深入分析。开展了不同荷电状态(State of Charge, SOC)60 Ah磷酸铁锂电池热失控试验,根据电池温度演变曲线,将电池热失控过程分成三个阶段;依据电池产气曲线,将电池产气过程分为四个阶段;使用FLACS软件建模对预混气体进行了爆炸仿真,探索了SOC对可燃气体燃爆行为的影响规律,混合可燃气体的爆炸上下限和爆炸超压随着SOC的增大而增大。研究成果对储能电站的安全防护具有理论指导意义。展开更多
[ Objective] The study was to investigate the volatile components of secondary metabolites from M. alpine producing arachidonic acid and explore the changes in its metabolic pathway. [ Method] The air above M. alpine ...[ Objective] The study was to investigate the volatile components of secondary metabolites from M. alpine producing arachidonic acid and explore the changes in its metabolic pathway. [ Method] The air above M. alpine broth was extracted by solid-phase microextraction（SPME） during the post-exponential phase of growth and analyzed by GC-MS. [Result] 13 compounds were identified, 12 of which were sesquiterpenes with C15H24 formula and accounting for 99.62% of the complete compounds. Thujopsene-（ 12）, α-Guaiene and Aristolene were three most sesquiterpenes accounting for 10.66%, 33.69% and 34.85% of total content respectively. It can be sufficiently certified that sesquiterpene metabolic pathway existing in M. alpine. [ Coclusion] Metabolic flux of sesquiterpene pathway increased to improve its mass accumulation, because one or several key enzyme genes mutation in isoprene or sesquiterpene pathway enhanced their activities during induction of mutation from initial strain.展开更多
[Objective] The paper was to study the climate conditions of celery indus- trial belt in Huluhe Basin. [Method] Using the climate data of Xiji national basic sta- tion during 1981 and 2010, the meteorological data dur...[Objective] The paper was to study the climate conditions of celery indus- trial belt in Huluhe Basin. [Method] Using the climate data of Xiji national basic sta- tion during 1981 and 2010, the meteorological data during crop growth period in 3 automatic weather stations along Huluhe Basin were carried out regression analysis, and the climate condition of west celery industrial belt was conducted hierarchical clustering analysis by SPSS. [Result] West celery industrial belt along Huluhe Basin could be divided into 2 growing regions： partially southern warm, rainy and early mature region, partially northern cold, rainless and late mature region. Years of practice proved that the small climate differences within 2 planting regions were more obvious, so these 2 planting regions could be further divided into 4 subre- glens： Xinglong warm, rainy and early mature subregion, Xiaohe thermal, rainy and partially early mature region, Jiqiang cool, rainless and middle mature subregion and Xinying cold, rainless and late mature subregion. [Conclusion] The study has refer- ence value for determination of different sowing time, different fertilizer and irrigation scheme, pests and diseased control and marketing time of west celery under mulch- sanded bunch plantation in market economic condition.展开更多
This article presents an acetylene production process by partial oxidation/combustion of natural gas. The thermodynamic performance and exergy analysis in the process are investigated using the flow-sheeting program A...This article presents an acetylene production process by partial oxidation/combustion of natural gas. The thermodynamic performance and exergy analysis in the process are investigated using the flow-sheeting program Aspen Plus. The results indicate that the most important destruction of exergy is found to occur in the reactor and water quenching scrubber, amounting to 8.23% and 10.39%, respectively, of the entire system. Based on the results of thermodynamic and exergy analysis, the acetylene reactor has been retrofitted. The improvement ratios of molar 02 to CH4 and molar CO to CN4 are 0.65 and 0.20, respectively. An improvement of the acetylene production system is proposed. Adopting the improvement operation conditions and using oil to realize the reaction heat recovery, the feedstock of natural gas is reduced by 9.88% and the exergy loss in the retrofitting process is decreased by 19.71% compared to the original process.展开更多
Developing low-carbon economy and enhancing carbon productivity are basic approaches to coordinating economic development and protecting global environment, which are also the major ways to address climate change unde...Developing low-carbon economy and enhancing carbon productivity are basic approaches to coordinating economic development and protecting global environment, which are also the major ways to address climate change under the framework of sustainable development. In this paper, the authors analyze the annual rate of carbon productivity growth, the differences of carbon productivity of different countries, and the factors for enhancing carbon productivity. Consequently, the authors clarify their viewpoint that the annual rate of carbon productivity growth can be used to weigh the efforts that a country takes to address climate change, and propose policies and suggestions on promoting carbon production.展开更多
The current cost-plus natural gas pricing mechanism makes the gas price too low,resulting in a lot of consumer-side subsidies and over-consumed natural gas.This paper applies the price-gap approach and input-output an...The current cost-plus natural gas pricing mechanism makes the gas price too low,resulting in a lot of consumer-side subsidies and over-consumed natural gas.This paper applies the price-gap approach and input-output analysis technology to quantitatively analyze both the direct and indirect effects on urban residents under the condition that natural gas subsidies are cancelled in China in 2007.It is shown that the gas price will increase by 33.3%-41.6%,and the residential consumption expenditure by 0.26%-0.33%.The low-income groups are mostly affected,so different subsidies should be implemented to make subsidies more efficient.展开更多
[Objective] The paper aims to study the effect of weather on rice production in Guangxi. [Method] The authors evaluated the effect of weather and weather disasters in Guangxi on rice production by comparison and analy...[Objective] The paper aims to study the effect of weather on rice production in Guangxi. [Method] The authors evaluated the effect of weather and weather disasters in Guangxi on rice production by comparison and analysis in terms of temperature,rain and sunlight in 2009. [Result] The study summarized the main favorable and unfavorable weather conditions of rice growth,and proposed the measures and suggestions to tend to interest and avoid harm on rice production in Guangxi. [Conclusion] This study provides references to the evaluations about effect of weather in Guangxi on rice production and suggestions on how to reduce weather disasters influence and ensure rice production security.展开更多
Aspen plus software was employed to simulate process. The system concludes gasification scrubbing system the opposed multi-burner gasifier （OMB） methanol production and purification shift system. The distributions o...Aspen plus software was employed to simulate process. The system concludes gasification scrubbing system the opposed multi-burner gasifier （OMB） methanol production and purification shift system. The distributions of ammonia con- centration in streams were obtained. The study demonstrates that ammonium crystallization problem caused by ammonia ac- cumulation, and if the process has ammonia exports its concentration will greatly reduced and the ammonia salt problem will effectively alleviate. Aspen plus simulation is a useful tool strengthening the ammonia recycling use and reducing pollutant for improving water quality, maintaining stable production, emissions.展开更多
Expecting that agricultural yield is highly dependent on climatic conditions, particularly water availability and suitable temperature, an agroclimatic study was carried out on rice crops during three different season...Expecting that agricultural yield is highly dependent on climatic conditions, particularly water availability and suitable temperature, an agroclimatic study was carried out on rice crops during three different seasons in four regions of Bangladesh. Data on climate （surface air temperature and precipitation） and seasonal rice production were examined for the period 1986-2006 from 18 rice growth observatories. The relationship between climate and rice production was statistically analyzed by removing long-term trends so that the effects of improved irrigation, which results in a general increase in crop production, may be removed. The analysis involved both single and multiple regressions. The results suggested that, during monsoon and summer, higher temperatures had negative effects on rice production, especially in the northwestern （NW） region. In winter, positive effects were observed throughout Bangladesh. Since the annual mean temperature was positively correlated with those in the three seasons individually, the annual temperature had negative effects on the annual rice production only in the NW region, while it had positive effects in the central and southern regions. With the exception of the NW region, it was basically dry, excessive rainfall both in summer and monsoon yielded floods and reduced rice yield. In winter, more rainfall showed positive effects on crop production only in the central region, which was least irrigated. These findings suggested that accelerated atmospheric warming would result in serious damage to crops during summer and monsoon. Reliable prediction of future crop production will rely on the temperature and rainfall trends in individual seasons.展开更多
Currently, biodiesel is presented as one of the best alternatives for gradually replacing the use of fossil fuels, but it has some factors that make it economically impractical if it does not have a government support...Currently, biodiesel is presented as one of the best alternatives for gradually replacing the use of fossil fuels, but it has some factors that make it economically impractical if it does not have a government support. For this reason, research efforts focused on this area have been responsible for optimizing the process of biodiesel production by different catalytic routes to achieve greater efficiency at a lower cost. In this case, the biggest problem has been the high cost generated by an investigation, which in many occasions is the main factor to decide if an investigation could be carried out. Trying to reduce these costs, in the current study, we are using a technique of glycerol quantification by volumetric methods and comparing obtained results with the chromatographic method, which is conventionally used and comparatively much more expensive. Biodiesel employee was obtained by an enzymatic catalysis process varying one of three process variables：oil：alcohol molar ratio, temperature and proportion of catalyst. The numerical differences obtained between the two quantification methods generated relative errors lower than 10%, resulting in some occasions lower than 1%. By gas chromatography analysis the best yield was obtained at the same conditions of the volumetric method, a temperature of 45 ℃, an oil：alcohol ratio 1：4 and 8 wt.% of catalyst, but a yield of 95.5% and 97.1%, respectively. Due to the high precision of gas chromatography, this method is used to carry out a surface response analysis obtaining as ideal operating conditions a temperature of 43.5 ℃, 8.9 wt.%. of catalyst and an oil：alcohol ratio 1：4.展开更多
In wine production, the typical characteristics of variety, defined by its place of their origin, contribute to the development of distinctive and unique wines. In the current study, we analyzed the effect of the envi...In wine production, the typical characteristics of variety, defined by its place of their origin, contribute to the development of distinctive and unique wines. In the current study, we analyzed the effect of the environment using vine response and grape composition as indicators. Four cv. Tannat vineyards in three different climatic regions of Uruguay with similar soil conditions were studied in 2008 and 2009. Vines grafted onto SO4 （Vitis berlandieri × Vitis riparia） rootstock and were trained on a trellis system. Weather information was obtained from weather stations （MMO standards）. At each vineyard, we recorded： yield per plant, pruning weight, leaf area and pre-dawn leaf water potential. We analyzed sugars, total acidity and pH, polyphenolic potential, organic acids and berry weight. Analysis of variance, Pearson correlations and discriminant analysis were carried out. The climate factors with the highest discriminant weight were water balance, degree days （〉 10 ℃） of maturation and rainfall during the vegetative growth period. Plant response allowed us to discriminate between vineyards regardless of the year and was consistent with climate. Exposed leaf area and length of maturation period were the indexes with the highest values, followed by leaf water potential and grape yield. The total anthocyanin content, sugar contents and their daily accumulation, and acid composition statistically separate regions regardless of the year. We concluded that plant response and grape composition were strongly influenced by water supply and thermal conditions during ripening.展开更多
Corrosion behavior of AZ91 magnesium alloy under NaCl particle deposition condition was investigated by gravimetric method and surface analysis technique.It was found that the mass gain increased rapidly at the beginn...Corrosion behavior of AZ91 magnesium alloy under NaCl particle deposition condition was investigated by gravimetric method and surface analysis technique.It was found that the mass gain increased rapidly at the beginning of exposure and then slowly with time.The corrosion morphologies were observed and the results showed that NaCl deposition resulted in the occurrence of localized corrosion.The composition of corrosion product was analyzed using X-ray photo electron spectroscopy.It was suggested that the corrosion product was a mixture of oxide and hydroxide of magnesium and aluminum.展开更多
Extreme climate events exhibit an increasing spatio-temporal trend globally, and the increasing intensity and frequency may have severe impacts on the human society and natural ecosystems. This study analyzed the extr...Extreme climate events exhibit an increasing spatio-temporal trend globally, and the increasing intensity and frequency may have severe impacts on the human society and natural ecosystems. This study analyzed the extreme temperature and precipitation variability from 1956 to 2016, and evaluated their potential effects on crop yield in Ethiopia. Relative extreme temperature indices exhibited a decreasing trend with low-temperature events, but a significantly upward trend with extreme high temperature events. The frequency of annual warm nights increased to a greater degree than that of cold days. The total annual wet-day precipitation decreased significantly at a rate of-46 mm/decade. Further, the succession of dry days gradually increased by 5.6 day/decade, while an opposite trend of wet days was found with a decline of 1.4 day/decade. The correlation between annual precipitation and crop production was 0.422, indicating that extreme precipitation indices may have higher explanatory power than extreme temperature indices in the crop yield variations. Moreover, the extreme climate changes have induced significant adverse impacts on crops yield particularly in Ethiopia where no proper adaptation measures have been implemented.展开更多
The appropriate production of liquefied natural gas(LNG)with least consuming energy and maximum efficiency is quite important.In this paper,LNG production cycle by means of APCI Process has been studied.Energy equilib...The appropriate production of liquefied natural gas(LNG)with least consuming energy and maximum efficiency is quite important.In this paper,LNG production cycle by means of APCI Process has been studied.Energy equilibrium equations and exergy equilibrium equations of each equipment in the APCI cycle were established.The equipments are described using rigorous thermodynamics and no significant simplification is assumed.Taken some operating parameters as key parameters,influences of these parameters on coefficient of performance(COP)and exergy efficiency of the cascading cycle were analyzed.The results indicate that COP and exergy efficiency will be improved with the increasing of the inlet pressure of MR(mixed refrigerant)compressors,the decreasing of the NG and MR after precooling process,outlet pressure of turbine,inlet temperature of MR compressor and NG temperature after cooling in main cryogenic heat exchanger(MCHE).The COP and exergy efficiency of the APCI cycle will be above 2% and 40%,respectively,after optimizing the key parameters.展开更多
Two new noble-metal-free molecular devices, [{Co（dmgH）2Cl}{Zn（PyTPP）}] （1, dmgH = dimethyloxime, PyTPP = 5-（4- pyridyl）-10,15,20-triphenylporphyrin） and [{Co（dmgH）2Cl}{Zn（apPyTPP）}] （2, apPyTPP = 5-[4-（i...Two new noble-metal-free molecular devices, [{Co（dmgH）2Cl}{Zn（PyTPP）}] （1, dmgH = dimethyloxime, PyTPP = 5-（4- pyridyl）-10,15,20-triphenylporphyrin） and [{Co（dmgH）2Cl}{Zn（apPyTPP）}] （2, apPyTPP = 5-[4-（isonicotinamidyl）phenyl]- 10,15,20-triphenylporphyrin）, for light-driven hydrogen generation were prepared and spectroscopically characterized. The zinc porphyrin photosensitizer and the Co III-based catalyst unit are linked by axial coordination of a pyridyl group in the periphery of zinc-porphyrin to the cobalt centre of catalyst with different lengths of bridges. The apparent fluorescence quenching and lifetime decays of 1 and 2 were observed in comparison with their reference chromophores, Zn（PyTPP） （3） and Zn（apPyTPP） （4）, suggesting a possibility for an intramolecular electron transfer from the singlet excited state of zinc porphyrin unit to the cobalt centre in the molecular devices. Photochemical H2-evolving studies show that complexes 1 and 2 are efficient molecular photocatalysts for visible light-driven H2 generation from water with triethylamine as a sacrificial electron donor in THF/H20, with turnover numbers up to 46 and 35 for 1 and 2, respectively. In contrast to these molecular devices, the multicomponent catalyst of zinc porphyrin and [Co（dmgH）2PyCl] did not show any fluorescence quenching and as a consequence, no H2 gas was detected by GC analysis in the presence of triethylamine with irradiation of visible light. The plausible mechanism for the photochemical H2 generation with these molecular devices is discussed.展开更多
Increasing pressure from the international community to reduce carbon emissions, coupled with the need to reduce domestic air pollutants, is forcing China to deal with both sources of emissions. Air pollutants and gre...Increasing pressure from the international community to reduce carbon emissions, coupled with the need to reduce domestic air pollutants, is forcing China to deal with both sources of emissions. Air pollutants and greenhouse gases are closely linked via their common source, fossil fuels. As a result of globalization, large portions of these emissions are associated with trade. This study uses data from the World Input-Output Database（WIOD）, including 27 EU countries and 13 major countries, covering the period from 2000 to 2009, and applies MRIO（Multiregional input-output） to estimate emissions embodied in China＇s international trade. We focus on the synergy between LAPs（local air pollutants） and GHG consumption-based emissions, and the relationship between virtual LAPs and virtual GHGs associated with China＇s international trade from 2000 to 2009. The results indicate that a strong synergistic relationship exists and that air pollutant control can serve as an endogenous mechanism to mitigating greenhouse gases. Thanks to domestic actions to control air pollutants, every ton reduction of LAP emissions related to export can save 27.1 tons of GHG emissions in 2005 over emissions efficiency levels, and can save 32.4 tons of GHG emissions in 2009 over 2005. Mitigation actions taken to reduce air pollutants could also reduce GHG emissions.展开更多
文摘新能源产业的飞速发展使磷酸铁锂电池广泛应用于储能领域。磷酸铁锂电池电解液固有的可燃性使其热稳定性和安全性问题不容忽视。为了更好地防控储能电站的爆炸事故,有必要开展储能电池的热失控过程研究,并对产气过程和产气组分的危害性进行深入分析。开展了不同荷电状态(State of Charge, SOC)60 Ah磷酸铁锂电池热失控试验,根据电池温度演变曲线,将电池热失控过程分成三个阶段;依据电池产气曲线,将电池产气过程分为四个阶段;使用FLACS软件建模对预混气体进行了爆炸仿真,探索了SOC对可燃气体燃爆行为的影响规律,混合可燃气体的爆炸上下限和爆炸超压随着SOC的增大而增大。研究成果对储能电站的安全防护具有理论指导意义。
基金Supported by the National Natural Science Foundation of China(20606018)the National Basic Research Program (also called 973Program)(2007CB707805)the Six Projects Sponsoring Talent Summits of Jiangsu Province~~
文摘[ Objective] The study was to investigate the volatile components of secondary metabolites from M. alpine producing arachidonic acid and explore the changes in its metabolic pathway. [ Method] The air above M. alpine broth was extracted by solid-phase microextraction（SPME） during the post-exponential phase of growth and analyzed by GC-MS. [Result] 13 compounds were identified, 12 of which were sesquiterpenes with C15H24 formula and accounting for 99.62% of the complete compounds. Thujopsene-（ 12）, α-Guaiene and Aristolene were three most sesquiterpenes accounting for 10.66%, 33.69% and 34.85% of total content respectively. It can be sufficiently certified that sesquiterpene metabolic pathway existing in M. alpine. [ Coclusion] Metabolic flux of sesquiterpene pathway increased to improve its mass accumulation, because one or several key enzyme genes mutation in isoprene or sesquiterpene pathway enhanced their activities during induction of mutation from initial strain.
基金Supported by Meteorological Science and Technology Project of Ningxia Meteorological Bureau in 2011 "West Celery Experiment of Sowing by Stages"~~
文摘[Objective] The paper was to study the climate conditions of celery indus- trial belt in Huluhe Basin. [Method] Using the climate data of Xiji national basic sta- tion during 1981 and 2010, the meteorological data during crop growth period in 3 automatic weather stations along Huluhe Basin were carried out regression analysis, and the climate condition of west celery industrial belt was conducted hierarchical clustering analysis by SPSS. [Result] West celery industrial belt along Huluhe Basin could be divided into 2 growing regions： partially southern warm, rainy and early mature region, partially northern cold, rainless and late mature region. Years of practice proved that the small climate differences within 2 planting regions were more obvious, so these 2 planting regions could be further divided into 4 subre- glens： Xinglong warm, rainy and early mature subregion, Xiaohe thermal, rainy and partially early mature region, Jiqiang cool, rainless and middle mature subregion and Xinying cold, rainless and late mature subregion. [Conclusion] The study has refer- ence value for determination of different sowing time, different fertilizer and irrigation scheme, pests and diseased control and marketing time of west celery under mulch- sanded bunch plantation in market economic condition.
基金Supported by the National Natural Science Foundation of China （90210032, 50576001）.
文摘This article presents an acetylene production process by partial oxidation/combustion of natural gas. The thermodynamic performance and exergy analysis in the process are investigated using the flow-sheeting program Aspen Plus. The results indicate that the most important destruction of exergy is found to occur in the reactor and water quenching scrubber, amounting to 8.23% and 10.39%, respectively, of the entire system. Based on the results of thermodynamic and exergy analysis, the acetylene reactor has been retrofitted. The improvement ratios of molar 02 to CH4 and molar CO to CN4 are 0.65 and 0.20, respectively. An improvement of the acetylene production system is proposed. Adopting the improvement operation conditions and using oil to realize the reaction heat recovery, the feedstock of natural gas is reduced by 9.88% and the exergy loss in the retrofitting process is decreased by 19.71% compared to the original process.
基金Major Project of Key Research Bases of Humanities and Social Sciences of Ministry of Education(05JJD630035)Major International Joint Research Program Founded by National Natural Science Foundation of China(50246003)Major Project(90410016)
文摘Developing low-carbon economy and enhancing carbon productivity are basic approaches to coordinating economic development and protecting global environment, which are also the major ways to address climate change under the framework of sustainable development. In this paper, the authors analyze the annual rate of carbon productivity growth, the differences of carbon productivity of different countries, and the factors for enhancing carbon productivity. Consequently, the authors clarify their viewpoint that the annual rate of carbon productivity growth can be used to weigh the efforts that a country takes to address climate change, and propose policies and suggestions on promoting carbon production.
基金Supported by Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA05150600)National Natural Science Foundation of China (No. 71041006 and No. 70903066)
文摘The current cost-plus natural gas pricing mechanism makes the gas price too low,resulting in a lot of consumer-side subsidies and over-consumed natural gas.This paper applies the price-gap approach and input-output analysis technology to quantitatively analyze both the direct and indirect effects on urban residents under the condition that natural gas subsidies are cancelled in China in 2007.It is shown that the gas price will increase by 33.3%-41.6%,and the residential consumption expenditure by 0.26%-0.33%.The low-income groups are mostly affected,so different subsidies should be implemented to make subsidies more efficient.
基金Supported by Guangxi Natural Fund Project (0832204 )Guangxi Agricultural Key Technological Project (200702)~~
文摘[Objective] The paper aims to study the effect of weather on rice production in Guangxi. [Method] The authors evaluated the effect of weather and weather disasters in Guangxi on rice production by comparison and analysis in terms of temperature,rain and sunlight in 2009. [Result] The study summarized the main favorable and unfavorable weather conditions of rice growth,and proposed the measures and suggestions to tend to interest and avoid harm on rice production in Guangxi. [Conclusion] This study provides references to the evaluations about effect of weather in Guangxi on rice production and suggestions on how to reduce weather disasters influence and ensure rice production security.
文摘Aspen plus software was employed to simulate process. The system concludes gasification scrubbing system the opposed multi-burner gasifier （OMB） methanol production and purification shift system. The distributions of ammonia con- centration in streams were obtained. The study demonstrates that ammonium crystallization problem caused by ammonia ac- cumulation, and if the process has ammonia exports its concentration will greatly reduced and the ammonia salt problem will effectively alleviate. Aspen plus simulation is a useful tool strengthening the ammonia recycling use and reducing pollutant for improving water quality, maintaining stable production, emissions.
文摘Expecting that agricultural yield is highly dependent on climatic conditions, particularly water availability and suitable temperature, an agroclimatic study was carried out on rice crops during three different seasons in four regions of Bangladesh. Data on climate （surface air temperature and precipitation） and seasonal rice production were examined for the period 1986-2006 from 18 rice growth observatories. The relationship between climate and rice production was statistically analyzed by removing long-term trends so that the effects of improved irrigation, which results in a general increase in crop production, may be removed. The analysis involved both single and multiple regressions. The results suggested that, during monsoon and summer, higher temperatures had negative effects on rice production, especially in the northwestern （NW） region. In winter, positive effects were observed throughout Bangladesh. Since the annual mean temperature was positively correlated with those in the three seasons individually, the annual temperature had negative effects on the annual rice production only in the NW region, while it had positive effects in the central and southern regions. With the exception of the NW region, it was basically dry, excessive rainfall both in summer and monsoon yielded floods and reduced rice yield. In winter, more rainfall showed positive effects on crop production only in the central region, which was least irrigated. These findings suggested that accelerated atmospheric warming would result in serious damage to crops during summer and monsoon. Reliable prediction of future crop production will rely on the temperature and rainfall trends in individual seasons.
文摘Currently, biodiesel is presented as one of the best alternatives for gradually replacing the use of fossil fuels, but it has some factors that make it economically impractical if it does not have a government support. For this reason, research efforts focused on this area have been responsible for optimizing the process of biodiesel production by different catalytic routes to achieve greater efficiency at a lower cost. In this case, the biggest problem has been the high cost generated by an investigation, which in many occasions is the main factor to decide if an investigation could be carried out. Trying to reduce these costs, in the current study, we are using a technique of glycerol quantification by volumetric methods and comparing obtained results with the chromatographic method, which is conventionally used and comparatively much more expensive. Biodiesel employee was obtained by an enzymatic catalysis process varying one of three process variables：oil：alcohol molar ratio, temperature and proportion of catalyst. The numerical differences obtained between the two quantification methods generated relative errors lower than 10%, resulting in some occasions lower than 1%. By gas chromatography analysis the best yield was obtained at the same conditions of the volumetric method, a temperature of 45 ℃, an oil：alcohol ratio 1：4 and 8 wt.% of catalyst, but a yield of 95.5% and 97.1%, respectively. Due to the high precision of gas chromatography, this method is used to carry out a surface response analysis obtaining as ideal operating conditions a temperature of 43.5 ℃, 8.9 wt.%. of catalyst and an oil：alcohol ratio 1：4.
文摘In wine production, the typical characteristics of variety, defined by its place of their origin, contribute to the development of distinctive and unique wines. In the current study, we analyzed the effect of the environment using vine response and grape composition as indicators. Four cv. Tannat vineyards in three different climatic regions of Uruguay with similar soil conditions were studied in 2008 and 2009. Vines grafted onto SO4 （Vitis berlandieri × Vitis riparia） rootstock and were trained on a trellis system. Weather information was obtained from weather stations （MMO standards）. At each vineyard, we recorded： yield per plant, pruning weight, leaf area and pre-dawn leaf water potential. We analyzed sugars, total acidity and pH, polyphenolic potential, organic acids and berry weight. Analysis of variance, Pearson correlations and discriminant analysis were carried out. The climate factors with the highest discriminant weight were water balance, degree days （〉 10 ℃） of maturation and rainfall during the vegetative growth period. Plant response allowed us to discriminate between vineyards regardless of the year and was consistent with climate. Exposed leaf area and length of maturation period were the indexes with the highest values, followed by leaf water potential and grape yield. The total anthocyanin content, sugar contents and their daily accumulation, and acid composition statistically separate regions regardless of the year. We concluded that plant response and grape composition were strongly influenced by water supply and thermal conditions during ripening.
基金Projects(50671005,50971093)supported by the National Natural Science Foundation of ChinaProject(2007CB613705)supported by the National Basic Research Program of China
文摘Corrosion behavior of AZ91 magnesium alloy under NaCl particle deposition condition was investigated by gravimetric method and surface analysis technique.It was found that the mass gain increased rapidly at the beginning of exposure and then slowly with time.The corrosion morphologies were observed and the results showed that NaCl deposition resulted in the occurrence of localized corrosion.The composition of corrosion product was analyzed using X-ray photo electron spectroscopy.It was suggested that the corrosion product was a mixture of oxide and hydroxide of magnesium and aluminum.
基金National Natural Science Foundation of China(4176114405341501539+5 种基金41420104004)National Key R&D Program of China(2017YFC0505706)International Partnership Program of Chinese Academy of Sciences(121311KYSB20170004)Key Technologies R&D program of Tianjin(16YFXTSF00380)Natural Science Foundation of Inner Mongolia Autonomous(2015KF0120131510)
文摘Extreme climate events exhibit an increasing spatio-temporal trend globally, and the increasing intensity and frequency may have severe impacts on the human society and natural ecosystems. This study analyzed the extreme temperature and precipitation variability from 1956 to 2016, and evaluated their potential effects on crop yield in Ethiopia. Relative extreme temperature indices exhibited a decreasing trend with low-temperature events, but a significantly upward trend with extreme high temperature events. The frequency of annual warm nights increased to a greater degree than that of cold days. The total annual wet-day precipitation decreased significantly at a rate of-46 mm/decade. Further, the succession of dry days gradually increased by 5.6 day/decade, while an opposite trend of wet days was found with a decline of 1.4 day/decade. The correlation between annual precipitation and crop production was 0.422, indicating that extreme precipitation indices may have higher explanatory power than extreme temperature indices in the crop yield variations. Moreover, the extreme climate changes have induced significant adverse impacts on crops yield particularly in Ethiopia where no proper adaptation measures have been implemented.
文摘The appropriate production of liquefied natural gas(LNG)with least consuming energy and maximum efficiency is quite important.In this paper,LNG production cycle by means of APCI Process has been studied.Energy equilibrium equations and exergy equilibrium equations of each equipment in the APCI cycle were established.The equipments are described using rigorous thermodynamics and no significant simplification is assumed.Taken some operating parameters as key parameters,influences of these parameters on coefficient of performance(COP)and exergy efficiency of the cascading cycle were analyzed.The results indicate that COP and exergy efficiency will be improved with the increasing of the inlet pressure of MR(mixed refrigerant)compressors,the decreasing of the NG and MR after precooling process,outlet pressure of turbine,inlet temperature of MR compressor and NG temperature after cooling in main cryogenic heat exchanger(MCHE).The COP and exergy efficiency of the APCI cycle will be above 2% and 40%,respectively,after optimizing the key parameters.
基金supported by the National Natural Science Foundation of China (20633020)the National Basic Research Program of China(2009CB220009)+2 种基金the Swedish Energy Agencythe Swedish Research Councilthe K & A Wallenberg Foundation
文摘Two new noble-metal-free molecular devices, [{Co（dmgH）2Cl}{Zn（PyTPP）}] （1, dmgH = dimethyloxime, PyTPP = 5-（4- pyridyl）-10,15,20-triphenylporphyrin） and [{Co（dmgH）2Cl}{Zn（apPyTPP）}] （2, apPyTPP = 5-[4-（isonicotinamidyl）phenyl]- 10,15,20-triphenylporphyrin）, for light-driven hydrogen generation were prepared and spectroscopically characterized. The zinc porphyrin photosensitizer and the Co III-based catalyst unit are linked by axial coordination of a pyridyl group in the periphery of zinc-porphyrin to the cobalt centre of catalyst with different lengths of bridges. The apparent fluorescence quenching and lifetime decays of 1 and 2 were observed in comparison with their reference chromophores, Zn（PyTPP） （3） and Zn（apPyTPP） （4）, suggesting a possibility for an intramolecular electron transfer from the singlet excited state of zinc porphyrin unit to the cobalt centre in the molecular devices. Photochemical H2-evolving studies show that complexes 1 and 2 are efficient molecular photocatalysts for visible light-driven H2 generation from water with triethylamine as a sacrificial electron donor in THF/H20, with turnover numbers up to 46 and 35 for 1 and 2, respectively. In contrast to these molecular devices, the multicomponent catalyst of zinc porphyrin and [Co（dmgH）2PyCl] did not show any fluorescence quenching and as a consequence, no H2 gas was detected by GC analysis in the presence of triethylamine with irradiation of visible light. The plausible mechanism for the photochemical H2 generation with these molecular devices is discussed.
基金Research fund project of Renmin University of China(17XNA014)
文摘Increasing pressure from the international community to reduce carbon emissions, coupled with the need to reduce domestic air pollutants, is forcing China to deal with both sources of emissions. Air pollutants and greenhouse gases are closely linked via their common source, fossil fuels. As a result of globalization, large portions of these emissions are associated with trade. This study uses data from the World Input-Output Database（WIOD）, including 27 EU countries and 13 major countries, covering the period from 2000 to 2009, and applies MRIO（Multiregional input-output） to estimate emissions embodied in China＇s international trade. We focus on the synergy between LAPs（local air pollutants） and GHG consumption-based emissions, and the relationship between virtual LAPs and virtual GHGs associated with China＇s international trade from 2000 to 2009. The results indicate that a strong synergistic relationship exists and that air pollutant control can serve as an endogenous mechanism to mitigating greenhouse gases. Thanks to domestic actions to control air pollutants, every ton reduction of LAP emissions related to export can save 27.1 tons of GHG emissions in 2005 over emissions efficiency levels, and can save 32.4 tons of GHG emissions in 2009 over 2005. Mitigation actions taken to reduce air pollutants could also reduce GHG emissions.
