The static O-H bond parameters including O-H bond length, O-H charge difference, O-H Mulliken population and O-H bond stretching force constant (k) for 17 phenols were calculated by ab initio method HF/6-31G**. In com...The static O-H bond parameters including O-H bond length, O-H charge difference, O-H Mulliken population and O-H bond stretching force constant (k) for 17 phenols were calculated by ab initio method HF/6-31G**. In combination with the O-H bond dissociation enthalpies (BDE) of the phenols determined by experiment, it was found that there were poor correlationships between the static O-H bond parameters and O-H BDE. Considering the good correlationship bt tween O-H BDE and logarithm of free radical scavenging rate constant for phenolic antioxidant, it is reasonable to believe that the ineffectiveness of static O-H bond parameters in characterizing antioxidant activity arises from the fact that they cannot measure the O-H BDE.展开更多
The mechanism underlying pollen tube growth involves diverse genes and molecular pathways. Alterations in the regulatory genes or pathways cause phenotypic changes reflected by cellular morphology, which can be captur...The mechanism underlying pollen tube growth involves diverse genes and molecular pathways. Alterations in the regulatory genes or pathways cause phenotypic changes reflected by cellular morphology, which can be captured using fluorescence microscopy. Determining and classifying pollen tube morphological phenotypes in such microscopic images is key to our understanding the involvement of genes and pathways. In this context, we propose a computational method to extract quantitative morphological features, and demonstrate that these features reflect morphological differences relevant to distinguish different defects of pollen tube growth. The corresponding software tool furthermore includes a novel semi-automated image segmentation approach, allowing to highly accurately identify the boundary of a pollen tube in a microscopic image.展开更多
To elucidate the different lipid-oxidation potentials of aminoxylantioxidants, a kind of combined density functional theory (DFT) method was employed to calculateC―H bond dissociation enthalpies (BDEs) of a model lin...To elucidate the different lipid-oxidation potentials of aminoxylantioxidants, a kind of combined density functional theory (DFT) method was employed to calculateC―H bond dissociation enthalpies (BDEs) of a model linoleic acid (LH) and O―H BDEs of hydrogenatedaminoxyls. The higher the O―H BDE is, the more potent the aminoxyl to abstract the H-atom from LHand the stronger the LH-oxidation potential. Accordingly, the prooxidant activity differences ofaminoxyls were elucidated by the different O―H BDEs of hydrogenated aminoxyls, which were furtherclarified in terms of distinct electronic effects of the substituents.展开更多
This paper analyzes a mathematical model of the photosynthetic carbon metabolism, which incorporates not only the Calvin-Benson cycle, but also another two important metabolic pathways： starch synthesis and photoresp...This paper analyzes a mathematical model of the photosynthetic carbon metabolism, which incorporates not only the Calvin-Benson cycle, but also another two important metabolic pathways： starch synthesis and photorespiratory pathway. Theoretically, the paper shows the existence of steady states, stability and instability of the steady states, the effects of CO2 concentration on steady states. Especially, a critical point is found, the system has only one steady state with C02 concentration in the left neighborhood of the critical point, but has two with C02 concentration in the right neighborhood. In addition, the paper also explores the influence of C02 concentration on the efficiency of photosynthesis. These theoretical results not only provide insight to the kinetic behaviors of the photosynthetic carbon metabolism, but also can be used to help improving the efficiency of photosynthesis in plants.展开更多
The multiple,complex and systemic problems of the agriculture-food-water-environment nexus(“Nexus”)are among the most significant challenges of the 21st century.China is a key site for Nexus research amidst profound...The multiple,complex and systemic problems of the agriculture-food-water-environment nexus(“Nexus”)are among the most significant challenges of the 21st century.China is a key site for Nexus research amidst profound socio-environmental problems.The policy implications of these problems have been authoritatively summarized elsewhere.This study presents discussions at an international workshop in Guangzhou that asked instead“What science is needed to deliver the growing policy commitments regarding these challenges?And,What changes are needed to the science itself?”Understanding and effective intervention regarding the Nexus calls for a paradigm shift:to a new kind of science of(capacity for)international,interdisciplinary,and impactful research working with and within complex socio-natural systems.We here argue that science must become proactive in approach,striving only for“minimal harm”not“silver bullet”solutions,and adopting an explicitly long-term strategic perspective.Together,these arguments lead to calls for reorienting science and science policy in three ways:from short-term remediation to longer-term optimization;from a focus on environmental threats to one on the opportunities for international collaborative learning;and toward supporting new forms of scientific career.We bring these points together by recommending a new form of scientific institution:a global network of collaborative Nexus Centres,under the umbrella of a global Food Nexus Organization akin to those of the human genome and proteome.展开更多
基金Acknowledgments We thank Gaoyang Zhu for technical assistance. This work was supported by grants from the National Natural Science Foundation of China （30930050, 30921004）, the 973 Program （2006CB943401, 2010CB833706） to YGC, and grants from the China National Science Foundation （Grant # 30890033, 30588001 and 30620120433）, Chinese Ministry of Science and Technology（Grant # 2006CB910700） to JDH.
文摘The static O-H bond parameters including O-H bond length, O-H charge difference, O-H Mulliken population and O-H bond stretching force constant (k) for 17 phenols were calculated by ab initio method HF/6-31G**. In combination with the O-H bond dissociation enthalpies (BDE) of the phenols determined by experiment, it was found that there were poor correlationships between the static O-H bond parameters and O-H BDE. Considering the good correlationship bt tween O-H BDE and logarithm of free radical scavenging rate constant for phenolic antioxidant, it is reasonable to believe that the ineffectiveness of static O-H bond parameters in characterizing antioxidant activity arises from the fact that they cannot measure the O-H BDE.
基金supported by a Chinese Academy of Sciences Visiting Professorship for Senior International Scientists (2011T1S11) to A.M.the National Natural Science Foundation of China (30970266) to D.Z
文摘The mechanism underlying pollen tube growth involves diverse genes and molecular pathways. Alterations in the regulatory genes or pathways cause phenotypic changes reflected by cellular morphology, which can be captured using fluorescence microscopy. Determining and classifying pollen tube morphological phenotypes in such microscopic images is key to our understanding the involvement of genes and pathways. In this context, we propose a computational method to extract quantitative morphological features, and demonstrate that these features reflect morphological differences relevant to distinguish different defects of pollen tube growth. The corresponding software tool furthermore includes a novel semi-automated image segmentation approach, allowing to highly accurately identify the boundary of a pollen tube in a microscopic image.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .3 0 10 0 0 3 5 )
文摘To elucidate the different lipid-oxidation potentials of aminoxylantioxidants, a kind of combined density functional theory (DFT) method was employed to calculateC―H bond dissociation enthalpies (BDEs) of a model linoleic acid (LH) and O―H BDEs of hydrogenatedaminoxyls. The higher the O―H BDE is, the more potent the aminoxyl to abstract the H-atom from LHand the stronger the LH-oxidation potential. Accordingly, the prooxidant activity differences ofaminoxyls were elucidated by the different O―H BDEs of hydrogenated aminoxyls, which were furtherclarified in terms of distinct electronic effects of the substituents.
基金Supported by the National Natural Science Foundation of China(No.11071238)the Key Lab of Random Complex Structures and Data Science,CAS(No.2008DP173182)the National Center for Mathematics and interdisciplinary Sciences,CAS(N0.Y029184K51)
文摘This paper analyzes a mathematical model of the photosynthetic carbon metabolism, which incorporates not only the Calvin-Benson cycle, but also another two important metabolic pathways： starch synthesis and photorespiratory pathway. Theoretically, the paper shows the existence of steady states, stability and instability of the steady states, the effects of CO2 concentration on steady states. Especially, a critical point is found, the system has only one steady state with C02 concentration in the left neighborhood of the critical point, but has two with C02 concentration in the right neighborhood. In addition, the paper also explores the influence of C02 concentration on the efficiency of photosynthesis. These theoretical results not only provide insight to the kinetic behaviors of the photosynthetic carbon metabolism, but also can be used to help improving the efficiency of photosynthesis in plants.
基金the funding of the European Union EuropeAid for the SEW-REAP project(ECRIP 348-010)that has sponsored the work behind this article.
文摘The multiple,complex and systemic problems of the agriculture-food-water-environment nexus(“Nexus”)are among the most significant challenges of the 21st century.China is a key site for Nexus research amidst profound socio-environmental problems.The policy implications of these problems have been authoritatively summarized elsewhere.This study presents discussions at an international workshop in Guangzhou that asked instead“What science is needed to deliver the growing policy commitments regarding these challenges?And,What changes are needed to the science itself?”Understanding and effective intervention regarding the Nexus calls for a paradigm shift:to a new kind of science of(capacity for)international,interdisciplinary,and impactful research working with and within complex socio-natural systems.We here argue that science must become proactive in approach,striving only for“minimal harm”not“silver bullet”solutions,and adopting an explicitly long-term strategic perspective.Together,these arguments lead to calls for reorienting science and science policy in three ways:from short-term remediation to longer-term optimization;from a focus on environmental threats to one on the opportunities for international collaborative learning;and toward supporting new forms of scientific career.We bring these points together by recommending a new form of scientific institution:a global network of collaborative Nexus Centres,under the umbrella of a global Food Nexus Organization akin to those of the human genome and proteome.
