A novel chitinolytic and chitosanolytic bacterium, Sphingomonas sp. CJ-5, has been isolated and characterized. It secretes both chitinase and chitosanase into surrounding medium in response to chitin or chitosan induc...A novel chitinolytic and chitosanolytic bacterium, Sphingomonas sp. CJ-5, has been isolated and characterized. It secretes both chitinase and chitosanase into surrounding medium in response to chitin or chitosan induction. To characterize the enzymes, both chitinase and chitosanase were purified by ammonium sulfate precipitation, Sephadex G-200 gel filtration and DEAE-Sepharose Fast Flow. SDS-PAGE analysis demonstrated molecular masses of chitinase and chitosanase were 230 kDa and 45 kDa respectively. The optimum hydrolysis conditions for chitinase were about pH 7.0 and 36 ℃, and these for chitosanase were pH 6.5 and 56 ℃, respectively. Both enzymes were quite stable up to 45 ℃ for one hour at pH 5-8. These results show that CJ-5 may have potential for industrial application particularly in recycling of chitin wastes.展开更多
Using directional distance function and nonparametric data envelopment analys&, th& paper estimates the environmental total factor productivity (ETFP) of energy-intensive industries in China from 1995 to 2010, and...Using directional distance function and nonparametric data envelopment analys&, th& paper estimates the environmental total factor productivity (ETFP) of energy-intensive industries in China from 1995 to 2010, and performs an empirical analysis on factors affecting ETFP growth after studying the differences of energy-intensive industries ' ETFP by industries and provinces. The findings include the following: energy-intensive industries 'ETFP growth is mainly driven by technical progress; China, at its current development stage, still has the potential to raise the productivity of its energy- intensive industries. By estimating the provincial data, we find that the ETFP growth of different provinces converge at different levels. Further market liberalization, increased FDl flows and reductions in energy intensity will help to improve each province's ETFP growth. In addition, increasing investment in energy saving and emissions reduction and improving corporate environmental management capacity can help to reduce a company's short-term cost of complying with environmental regulations.展开更多
Spherical polystyrene‐supported ammonium salts containing different linking chains between the support and ammonium groups were prepared as efficient and easily reusable heterogeneous catalysts for the cycloadditions...Spherical polystyrene‐supported ammonium salts containing different linking chains between the support and ammonium groups were prepared as efficient and easily reusable heterogeneous catalysts for the cycloadditions of CO2and epoxides.The effects of the length of the linking chains and a hydroxyl group pendent on the linking chain on the catalytic performance of ionic liquid immobilized catalysts and their mechanisms were studied through experiments and density functional theory calculations.It was found that,compared with a short linking chain,a long chain can make the halogen anion more negative and provide a larger contact area of the catalysts with the reactants,thus enhancing the reaction kinetics.The hydroxyl group can stretch the C-O bonds of the epoxides,promoting the reaction thermodynamics.As a result,for the cycloaddition of propylene oxide,the yield of propylene carbonate is much higher for the catalyst with a long linking chain(yield:91.4%)compared with the yield for that with a short chain(yield:70.9%),and is further increased in the presence of pendent hydroxyl groups(yield:98.5%).The catalyst also shows a high catalytic activity even at mild temperature and good reusability(yield:≥96%for10cycles),and the selectivity is always above99%.展开更多
In Eastern Africa, the experience of Machakos has been heavily debated between Malthusians and the more optimistic Boserupians. Machakos was the epitome of overpopulation and resource degradation in the 1950s, but has...In Eastern Africa, the experience of Machakos has been heavily debated between Malthusians and the more optimistic Boserupians. Machakos was the epitome of overpopulation and resource degradation in the 1950s, but has since thrived. The Boserupians view Machakos as an illustration of how population growth can solve rather than exacerbate the vicious cycle of poverty and resource degradation. The question arises whether Machakos is unique. This study investigates the role of social capital in Machakos. Using principal component analysis, the authors estimate various dimensions of social capital and find significant differences between Machakos and two other Kenyan regions particularly when it comes to the formation of associations.展开更多
The closed-loop stability issue of finite-precision realizations was investigated for digital control-lers implemented in block-floating-point format. The controller coefficient perturbation was analyzed resultingfrom...The closed-loop stability issue of finite-precision realizations was investigated for digital control-lers implemented in block-floating-point format. The controller coefficient perturbation was analyzed resultingfrom using finite word length (FWL) block-floating-point representation scheme. A block-floating-point FWL closed-loop stability measure was derived which considers both the dynamic range and precision. To facilitate the design of optimal finite-precision controller realizations, a computationally tractable block-floating-point FWL closed-loop stability measure was then introduced and the method of computing the value of this measure for a given controller realization was developed. The optimal controller realization is defined as the solution that maximizes the corresponding measure, and a numerical optimization approach was adopted to solve the resulting optimal realization problem. A numerical example was used to illustrate the design procedure and to compare the optimal controller realization with the initial realization.展开更多
Gastrointestinal cancer is one of the highly prevalent malignant diseases worldwide which is a major cause of morbidity and mortality. Gastric cancer is the second leading cause of cancer mortality in the world and it...Gastrointestinal cancer is one of the highly prevalent malignant diseases worldwide which is a major cause of morbidity and mortality. Gastric cancer is the second leading cause of cancer mortality in the world and its management, especially in advanced stages, has evolved relatively little [1]. Colorectal cancer (CRC) remains the third most common ma-lignancy and the third leading cause of cancer death worldwide [2]. The surgical treatment is still the most effective therapy for the gastrointestinal cancer. However, the majority of the patients had lost the opporunity of surgical therapy when it was detected at advanced stage, so to seek means other than surgical treatment of gastrointestinal cancer metastasis and recur-rence also has an important significance. With the deeping research of the molecular biology, molecular targeted therapy has become the hotspot and focus of comprehensive treatment of gastrointestinal cancer which is proposed against the molecular biological targets such as tumor cell growth, apoptosis, cell cycle, invasion and angiogenesis. Molecular targeted therapy can be grouped into six main areas: the epidermal growth factor receptor (EGFR) inhibitors, anti-angiogenic factors, cell cycle inhibitors, apoptosis promoters and matrix metalloproteinase inhibitors, cyclooxygenase inhibitors. The review of the progress are as follows.展开更多
Zinc halide-complexed alkyl-bridged bi-heterocycles were obtained as zwitterions from the Click reaction of a series of N-cyanoalkyl-N-alkylimidazolium halide ionic liquids with sodium azide. Reaction optimization sho...Zinc halide-complexed alkyl-bridged bi-heterocycles were obtained as zwitterions from the Click reaction of a series of N-cyanoalkyl-N-alkylimidazolium halide ionic liquids with sodium azide. Reaction optimization showed fast reaction times and milder conditions compared to conventional Click syntheses from neutral nitriles.展开更多
Adult stem cells(SCs) exist in all tissues that promote tissue growth, regeneration, and healing throughout life. The SC niche in which they reside provides signals that direct them to proliferate, differentiate, or r...Adult stem cells(SCs) exist in all tissues that promote tissue growth, regeneration, and healing throughout life. The SC niche in which they reside provides signals that direct them to proliferate, differentiate, or remain dormant; these factors include neighboring cells, the extracellular matrix, soluble molecules, and physical stimuli. In disease and aging states, stable or transitory changes in the microenvironment can directly cause SC activation or inhibition in tissue healing as well as functional regulation. Here, we discuss the microenvironmental regulation of the behavior of SC and focus on plasticity approaches by which various environmental factors can enhance the function of SCs and more effectively direct the fate of SCs.展开更多
With the boom of portable,wearable,and implantable smart electronics in the last decade,the demand for multifunctional microscale electrochemical energy storage devices has increased.Owing to their excellent rate perf...With the boom of portable,wearable,and implantable smart electronics in the last decade,the demand for multifunctional microscale electrochemical energy storage devices has increased.Owing to their excellent rate performance,high power density,long cycling lifetime,easy fabrication,and integration,multifunctional planar microsupercapacitors(PMSCs)are deemed as one of the ideal micropower sources for next-generation flexible on-chip electronics.Therefore,we offer a comprehensive overview of the recent progress regarding multifunctional devices based on PMSCs,including stretchable,self-healing,stimulus-responsive,thermosensitive,biodegradable,and temperaturetolerant microdevices.We also emphasize the unique applications of multifunctionally integrated PMSCs in the construction of self-powered and sensor-integrated systems in terms of multifunctional operation modes.Finally,the key challenges and future prospects related to these multifunctional devices are discussed to stimulate further research in this flourishing field.展开更多
基金Project supported by the Marine Bureau of Zhejiang Province, China
文摘A novel chitinolytic and chitosanolytic bacterium, Sphingomonas sp. CJ-5, has been isolated and characterized. It secretes both chitinase and chitosanase into surrounding medium in response to chitin or chitosan induction. To characterize the enzymes, both chitinase and chitosanase were purified by ammonium sulfate precipitation, Sephadex G-200 gel filtration and DEAE-Sepharose Fast Flow. SDS-PAGE analysis demonstrated molecular masses of chitinase and chitosanase were 230 kDa and 45 kDa respectively. The optimum hydrolysis conditions for chitinase were about pH 7.0 and 36 ℃, and these for chitosanase were pH 6.5 and 56 ℃, respectively. Both enzymes were quite stable up to 45 ℃ for one hour at pH 5-8. These results show that CJ-5 may have potential for industrial application particularly in recycling of chitin wastes.
文摘Using directional distance function and nonparametric data envelopment analys&, th& paper estimates the environmental total factor productivity (ETFP) of energy-intensive industries in China from 1995 to 2010, and performs an empirical analysis on factors affecting ETFP growth after studying the differences of energy-intensive industries ' ETFP by industries and provinces. The findings include the following: energy-intensive industries 'ETFP growth is mainly driven by technical progress; China, at its current development stage, still has the potential to raise the productivity of its energy- intensive industries. By estimating the provincial data, we find that the ETFP growth of different provinces converge at different levels. Further market liberalization, increased FDl flows and reductions in energy intensity will help to improve each province's ETFP growth. In addition, increasing investment in energy saving and emissions reduction and improving corporate environmental management capacity can help to reduce a company's short-term cost of complying with environmental regulations.
基金supported by the National Natural Science Foundation of China(21406031,21476044,U1663223)the Changjiang Scholars Program(T2012049)+3 种基金the State Key Laboratory of Fine Chemicals(KF1507)Dalian High-Level Talent Support Program(2015R056)Education Department of the Liaoning Province of China(LT2015007)Fundamental Research Funds for the Central Universities(DUT16TD19)~~
文摘Spherical polystyrene‐supported ammonium salts containing different linking chains between the support and ammonium groups were prepared as efficient and easily reusable heterogeneous catalysts for the cycloadditions of CO2and epoxides.The effects of the length of the linking chains and a hydroxyl group pendent on the linking chain on the catalytic performance of ionic liquid immobilized catalysts and their mechanisms were studied through experiments and density functional theory calculations.It was found that,compared with a short linking chain,a long chain can make the halogen anion more negative and provide a larger contact area of the catalysts with the reactants,thus enhancing the reaction kinetics.The hydroxyl group can stretch the C-O bonds of the epoxides,promoting the reaction thermodynamics.As a result,for the cycloaddition of propylene oxide,the yield of propylene carbonate is much higher for the catalyst with a long linking chain(yield:91.4%)compared with the yield for that with a short chain(yield:70.9%),and is further increased in the presence of pendent hydroxyl groups(yield:98.5%).The catalyst also shows a high catalytic activity even at mild temperature and good reusability(yield:≥96%for10cycles),and the selectivity is always above99%.
文摘In Eastern Africa, the experience of Machakos has been heavily debated between Malthusians and the more optimistic Boserupians. Machakos was the epitome of overpopulation and resource degradation in the 1950s, but has since thrived. The Boserupians view Machakos as an illustration of how population growth can solve rather than exacerbate the vicious cycle of poverty and resource degradation. The question arises whether Machakos is unique. This study investigates the role of social capital in Machakos. Using principal component analysis, the authors estimate various dimensions of social capital and find significant differences between Machakos and two other Kenyan regions particularly when it comes to the formation of associations.
文摘The closed-loop stability issue of finite-precision realizations was investigated for digital control-lers implemented in block-floating-point format. The controller coefficient perturbation was analyzed resultingfrom using finite word length (FWL) block-floating-point representation scheme. A block-floating-point FWL closed-loop stability measure was derived which considers both the dynamic range and precision. To facilitate the design of optimal finite-precision controller realizations, a computationally tractable block-floating-point FWL closed-loop stability measure was then introduced and the method of computing the value of this measure for a given controller realization was developed. The optimal controller realization is defined as the solution that maximizes the corresponding measure, and a numerical optimization approach was adopted to solve the resulting optimal realization problem. A numerical example was used to illustrate the design procedure and to compare the optimal controller realization with the initial realization.
文摘Gastrointestinal cancer is one of the highly prevalent malignant diseases worldwide which is a major cause of morbidity and mortality. Gastric cancer is the second leading cause of cancer mortality in the world and its management, especially in advanced stages, has evolved relatively little [1]. Colorectal cancer (CRC) remains the third most common ma-lignancy and the third leading cause of cancer death worldwide [2]. The surgical treatment is still the most effective therapy for the gastrointestinal cancer. However, the majority of the patients had lost the opporunity of surgical therapy when it was detected at advanced stage, so to seek means other than surgical treatment of gastrointestinal cancer metastasis and recur-rence also has an important significance. With the deeping research of the molecular biology, molecular targeted therapy has become the hotspot and focus of comprehensive treatment of gastrointestinal cancer which is proposed against the molecular biological targets such as tumor cell growth, apoptosis, cell cycle, invasion and angiogenesis. Molecular targeted therapy can be grouped into six main areas: the epidermal growth factor receptor (EGFR) inhibitors, anti-angiogenic factors, cell cycle inhibitors, apoptosis promoters and matrix metalloproteinase inhibitors, cyclooxygenase inhibitors. The review of the progress are as follows.
基金supported by the US Air Force Office of Scientific Research (F49550-10-1-0521)
文摘Zinc halide-complexed alkyl-bridged bi-heterocycles were obtained as zwitterions from the Click reaction of a series of N-cyanoalkyl-N-alkylimidazolium halide ionic liquids with sodium azide. Reaction optimization showed fast reaction times and milder conditions compared to conventional Click syntheses from neutral nitriles.
基金supported in part by the National Basic Research Program of China(2012CB518103,2012CB518105)National High Technology Research and Development Program of Ministry of Science and Technology of China(2013AA020105,2012AA020502)National Natural Science Foundation of China(81121004,81230041,31400822)
文摘Adult stem cells(SCs) exist in all tissues that promote tissue growth, regeneration, and healing throughout life. The SC niche in which they reside provides signals that direct them to proliferate, differentiate, or remain dormant; these factors include neighboring cells, the extracellular matrix, soluble molecules, and physical stimuli. In disease and aging states, stable or transitory changes in the microenvironment can directly cause SC activation or inhibition in tissue healing as well as functional regulation. Here, we discuss the microenvironmental regulation of the behavior of SC and focus on plasticity approaches by which various environmental factors can enhance the function of SCs and more effectively direct the fate of SCs.
基金the National Natural Science Foundation of China(NSFC,22109009,21975027,22035005,and 52073159)China Postdoctoral Science Foundation(2020M680376)+1 种基金the National Key R&D Program of China(2017YFB1104300)the NSFCSTINT(21911530143).
文摘With the boom of portable,wearable,and implantable smart electronics in the last decade,the demand for multifunctional microscale electrochemical energy storage devices has increased.Owing to their excellent rate performance,high power density,long cycling lifetime,easy fabrication,and integration,multifunctional planar microsupercapacitors(PMSCs)are deemed as one of the ideal micropower sources for next-generation flexible on-chip electronics.Therefore,we offer a comprehensive overview of the recent progress regarding multifunctional devices based on PMSCs,including stretchable,self-healing,stimulus-responsive,thermosensitive,biodegradable,and temperaturetolerant microdevices.We also emphasize the unique applications of multifunctionally integrated PMSCs in the construction of self-powered and sensor-integrated systems in terms of multifunctional operation modes.Finally,the key challenges and future prospects related to these multifunctional devices are discussed to stimulate further research in this flourishing field.