Despite of its great importance, the detailed molecular mechanism for carbohydrate pyrolysis remains poorly understood. We perform a density functional study with a newly developed XYG3 functional on the processes for...Despite of its great importance, the detailed molecular mechanism for carbohydrate pyrolysis remains poorly understood. We perform a density functional study with a newly developed XYG3 functional on the processes for D-glucose pyrolysis to acrolein. The most feasible reaction pathway starts from an isomerization from D-glucose to D-fructose, which then undergoes a cyclic Grob fragmentation, followed by a concerted electrocyclic dehydration to yield acrolein. This mechanism can account for the known experimental results.展开更多
A novel marine microbial esterase PHE14 was cloned from the genome of Pseudomonas oryzihabit‐ans HUP022 isolated from the deep sea of the western Pacific Ocean. Esterase PHE14 exhibited very good tolerance to most or...A novel marine microbial esterase PHE14 was cloned from the genome of Pseudomonas oryzihabit‐ans HUP022 isolated from the deep sea of the western Pacific Ocean. Esterase PHE14 exhibited very good tolerance to most organic solvents, surfactants and metal ions tested, thus making it a good esterase candidate for organic synthesis that requires an organic solvent, surfactants or metal ions. Esterase PHE14 was utilized as a biocatalyst in the asymmetric synthesis of D‐methyl lactate by enzymatic kinetic resolution. D‐methyl lactate is a key chiral chemical. Contrary to some previous reports, the addition of an organic solvent and surfactants in the enzymatic reaction did not have a beneficial effect on the kinetic resolution catalyzed by esterase PHE14. Our study is the first report on the preparation of the enantiomerically enriched product D‐methyl lactate by enzymatic kinetic resolution. The desired enantiomerically enriched product D‐methyl lactate was obtained with a high enantiomeric excess of 99%and yield of 88.7%after process optimization. The deep sea mi‐crobial esterase PHE14 is a green biocatalyst with very good potential in asymmetric synthesis in industry and can replace the traditional organic synthesis that causes pollution to the environment.展开更多
We study the D-dimensional Schr6dinger equation for an energy-dependent Hamiltonian that linearly depends on energy and quadraticly on the relative distance. Next, via the Nikiforov-Uvarov （NU） method, we calculate ...We study the D-dimensional Schr6dinger equation for an energy-dependent Hamiltonian that linearly depends on energy and quadraticly on the relative distance. Next, via the Nikiforov-Uvarov （NU） method, we calculate the corresponding eigenfunctions and eigenvalues.展开更多
Approximate analytical solutions of the D-dimensional Klein-Gordon equation are obtained for the scalarand vector general Hulthen-type potential and position-dependent mass with any l by using the concept of supersymm...Approximate analytical solutions of the D-dimensional Klein-Gordon equation are obtained for the scalarand vector general Hulthen-type potential and position-dependent mass with any l by using the concept of supersymmetricquantum mechanics (SUSYQM).The problem is numerically discussed for some cases of parameters.展开更多
基金Acknowledgments This work was supported by the National Natural Science Foundation of China （No.I0774126） and the Ministry of Science and Technology （No.2007CB815206 and No.2011CB808505）.
文摘Despite of its great importance, the detailed molecular mechanism for carbohydrate pyrolysis remains poorly understood. We perform a density functional study with a newly developed XYG3 functional on the processes for D-glucose pyrolysis to acrolein. The most feasible reaction pathway starts from an isomerization from D-glucose to D-fructose, which then undergoes a cyclic Grob fragmentation, followed by a concerted electrocyclic dehydration to yield acrolein. This mechanism can account for the known experimental results.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA11030404)Key Project from the Chinese Academy of Sciences (KGZD-EW-606)+1 种基金the National Natural Science Foundation of China (21302199)Guangzhou Science and Technology Plan Projects (201510010012)~~
文摘A novel marine microbial esterase PHE14 was cloned from the genome of Pseudomonas oryzihabit‐ans HUP022 isolated from the deep sea of the western Pacific Ocean. Esterase PHE14 exhibited very good tolerance to most organic solvents, surfactants and metal ions tested, thus making it a good esterase candidate for organic synthesis that requires an organic solvent, surfactants or metal ions. Esterase PHE14 was utilized as a biocatalyst in the asymmetric synthesis of D‐methyl lactate by enzymatic kinetic resolution. D‐methyl lactate is a key chiral chemical. Contrary to some previous reports, the addition of an organic solvent and surfactants in the enzymatic reaction did not have a beneficial effect on the kinetic resolution catalyzed by esterase PHE14. Our study is the first report on the preparation of the enantiomerically enriched product D‐methyl lactate by enzymatic kinetic resolution. The desired enantiomerically enriched product D‐methyl lactate was obtained with a high enantiomeric excess of 99%and yield of 88.7%after process optimization. The deep sea mi‐crobial esterase PHE14 is a green biocatalyst with very good potential in asymmetric synthesis in industry and can replace the traditional organic synthesis that causes pollution to the environment.
文摘We study the D-dimensional Schr6dinger equation for an energy-dependent Hamiltonian that linearly depends on energy and quadraticly on the relative distance. Next, via the Nikiforov-Uvarov （NU） method, we calculate the corresponding eigenfunctions and eigenvalues.
文摘Approximate analytical solutions of the D-dimensional Klein-Gordon equation are obtained for the scalarand vector general Hulthen-type potential and position-dependent mass with any l by using the concept of supersymmetricquantum mechanics (SUSYQM).The problem is numerically discussed for some cases of parameters.
