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Diastereoselective Michael Addition of (4'S)-Ethyl-3-(2',2'-Dimethyl-1',3'- dioxolan-4'-yl) acrylate with Furyl Lithium

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Chinese Chemical Letters 2001年第5期12卷 403-406页

作者： Dong mei HAN Xun Tian jianG jian Hong CHEN Bin WANG Dong lu BAI Shanghai Institute of Meteria Medica Shanghai Institutes for Biological SciencesChinese Academy of SciencesShanghai 200031

Michael addition of the chiral alpha,beta -unsaturated ester 2 with furyl lithium proceeded in syn manner with excellent diastereoselectivity. The diastereoselectivity was not affected by the configuration of the doub... 详细信息

关键词： Michael addition configuration determination syn addition.

THREE-DIMENSIONAL FLOW AROUND TWO TANDEM CIRCULAR CYLINDERS WITH VARIOUS SPACING AT Re=220

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Journal of Hydrodynamics 2006年第1期18卷 48-54页

作者： DENG jian REN An-lu ZOU jian-feng Department of Mechanics Zhejiang University Hangzhou 310027 China

The flow around two tandem circular cylinders was studied by a three-dimensional numerical simulation of the Navier-Stokes equations at Re=220 . The improved virtual boundary method was applied to model the no-slip boundary condition of the cylinders. The results show that as the spac ing ratio L/D≥4 , the three dimensionality occurs in the wake. When L/D≤3.5 the wake keeps a two-dimensional state at the Reynolds number Re=220 . The critical spacing for the appearance of three-dimensional instability obtained is at the range 3.5〈 L/D 〈 4, similar to the critical spacing found in two-dimensional case. Two sources of instability from upstream and downstream cylinder generate a complicat ed vortex structures in the wake, investigated by streamlines topology analysis in the streamwise plane. Many other interesting problems were also addressed in this paper.

关键词： three-dimensional Navier-Stokes equations,virtual boundary method flow around two tandem circular cylinders three-dimensional vortex structure

Current research on electrospinning of silk fibroin and its blends with natural and synthetic biodegradable polymers

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Frontiers of Materials Science 2013年第2期7卷 129-142页

作者： jian-Guang ZHANG Xiu-mei MO Biomaterials and Tissue Engineering Lab College of Chemistry Chemical Engineering & Biotechnology Donghua University Shanghai 201620 China

Silk fibroin （SF） is a kind of natural polymers with a great potential in biomedical application. Due to its good biocompatibility, biodegradability and minimal inflammatory reaction, SF is an excellent candidate for generating tissue engineering scaffolds. Electrospinning is a simple and effective method to fabricate nanofibers, which has several amazing characteristics such as very large surface area to volume ratio, flexibility in surface functionalities, and superior mechanical performance. The electro- spun nanofibers from SF and its blends have been used for varied tissue engineering. This paper will give a brief review about the structure, properties and applications of SF and blend nanofibers via electrospinning.

关键词： electrospinning nanofiber silk fibroin (SF) biodegradable polymer

A first-principles study of displacive β to ω transition in Ti-V alloys

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Progress in Natural Science:Materials International 2017年第6期27卷 703-708页

作者： Wei mei jian Sun Yufeng Wen Shanghai Key Laboratory of Advanced High-Temperature Materials and Precision Forming School of Materials Science and Engineering Shanghai Jiao Tong University School of Mathematical Sciences & Physics Jinggangshan University

The ground state properties of β and ω phases in Ti-(0–30 at%)V alloys were calculated, and subsequently thermodynamics and energy barriers of the displacive β to ω transition were investigated by first-principles. The results show that the lattice parameters of β and ω phases decreases with increasing V content in Ti-V alloys. The principal lattice strains for the β to ω transition are highly compositional dependent, and the volume variation decreases with increasing V content. The mechanical stability of the ω phase increases initially at the V content around 10 at% and then decreases with increasing V content. Based on the quasiharmonic Debye model, a metastable diffusionless phase diagram has been established, showing that the ω phase is thermodynamically more stable than the β phase at room temperature, anticipating a spontaneous transition from β to ω phases in Ti-V alloys. The calculations of energy pathways indicate that there is an energy barrier during the displacive βto ω transition in Ti-V alloys at temperatures from 100 to 500 K, but not at 0 K.

关键词： Elastic property Phase transition Ti-V alloys First-principles

Silencing of Transposable Elements by piRNAs in Drosophila:An Evolutionary Perspective

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Genomics, Proteomics & Bioinformatics 2017年第3期15卷 164-176页

作者： Shiqi luo jian lu State Key Laboratory of Protein and Plant Gene Research Center for BioinformaticsCollege of Life Sciences and Peking-Tsinghua Center for Life SciencesPeking University Beijing Advanced Innovation Center for Food Nutrition and Human Health College of Food Science and Nutritional EngineeringChina Agricultural University

Transposable elements （TEs） are DNA sequences that can move within the genome. TEs have greatly shaped the genomes, transcriptomes, and proteomes of the host organisms through a variety of mechanisms. However, TEs generally disrupt genes and destabilize the host genomes, which substantially reduce fitness of the host organisms. Understanding the genomic distribution and evolutionary dynamics of TEs will greatly deepen our understanding of the TE-mediated bio- logical processes. Most TE insertions are highly polymorphic in Drosophila melanogaster, providing us a good system to investigate the evolution of TEs at the population level. Decades of theoretical and experimental studies have well established ＂transposition-selection＂ population genetics model, which assumes that the equilibrium between TE replication and purifying selection determines the copy number of TEs in the genome. In the last decade, P-element-induced wimpy testis （PIW1）- interacting RNAs （piRNAs） were demonstrated to be master repressors of TE activities in Droso- phila, The discovery of piRNAs revolutionized our understanding of TE repression, because it reveals that the host organisms have evolved an adaptive mechanism to defend against TE invasion. Tremendous progress has been made to understand the molecular mechanisms by which piRNAs repress active TEs, although many details in this process remain to be further explored. The inter- action between piRNAs and TEs well explains the molecular mechanisms underlying hybrid dysge- nesis for the IoR and P-M systems in Drosophila, which have puzzled evolutionary biologists for decades. The piRNA repression pathway provides us an unparalleled system to study the co-evolutionary process between parasites and host organisms.

关键词： Transposable element piRNA Hybrid dysgenesis Evolution Drosophila

Mechanocaloric materials for solid-state cooling

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Science Bulletin 2015年第19期60卷 1638-1643页

作者： Binfeng lu jian Liu Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences

This article reviews the up-to-date progress in mechanocaloric effect and materials near ambient temperature. For elastocaloric materials, we focus on directly measured temperature change and its entropy origin in nonmagnetic and magnetic shape memory alloys. In terms of barocaloric materials, change in magnetic state, volume and shift of transition temperature due to hydrostatic pressure are systematically compared. We propose advantages and challenges of elastocaloric materials for solidstate cooling. Strategies to enhance elastocaloric and mechanical stability under long-term mechanical cycles are presented. Finally, we conclude with an outlook on the prospect of elastocaloric cooling application.

关键词： Elastocaloric effect Barocaloric effect Shape memory alloy Entropy

Changes in the Vascular Cylinder of Wild Soybean Roots Under Alkaline Stress

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Journal of Integrative Agriculture 2014年第10期13卷 2164-2169页

作者： NIU lu lu Jing-mei WU Dong-mei LI Yan GAO Ting-ting School of Life Sciences Northeast Normal University Qinghai Key Laboratory of Tibetan Medicine Pharmacology and Safety Evaluation Northwest Institute of Plateau BiologyChinese Academy of Sciences

Changes in the vascular cylinder of wild soybean （Glycine soja Sieb. et Zucc） roots under alkaline stress were investigated in an experiment that applied 90 mmol L1 alkaline stress for 10 d at the five-trifoliate plant growth stage in Huinan County, Jilin Province, China. Root samples were collected and paraffin-cut sections were made, and the root structure was observed under an optical microscope. There were significant changes in the vascular cylinder of G. soja roots under alkaline stress. Root diameter was reduced and the vascular cylinder changed from tetrarch to triarch pattern. Alkaline stress resulted in reduced, diameters of root vessels, and a large amount of residual, alkaline solution was stained cyaneous in vessels. The paratracheal parenchymatous cells of the vessels were large and there was little secondary xylem. Thus, alkaline stress caused structural changes in the vascular cylinder of G. soja.

关键词： Glycine soja Sieb. et Zucc alkaline stress anatomical structure tetrarch condition of vascular cylinder triarchcondition of vascular cylinder

Global patterns of fern species diversity:An evaluation of fern data in GBIF

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Plant Diversity 2022年第2期44卷 135-140页

作者： Hong Qian jian Zhang mei-Chen jiang Research and Collections Center Illinois State Museum1011 East Ash StreetSpringfieldIL 62703USA Zhejiang Tiantong Forest Ecosystem National Observation and Research Station School of Ecological and Environmental SciencesEast China Normal University200241 ShanghaiChina

Despite that several studies have shown that data derived from species lists generated from distribution occurrence records in the Global Biodiversity Information Facility(GBIF)are not appropriate for those ecological and biogeographic studies that require high sampling completeness,because species lists derived from GBIF are generally very incomplete,Suissa et al.(2021)generated fern species lists based on data with GBIF for 100 km×100 km grid cells across the world,and used the data to determine fern diversity hotspots and species richness-climate *** conduct an evaluation on the completeness of fern species lists derived from GBIF at the grid-cell scale and at a larger spatial scale,and determine whether fern data derived from GBIF are appropriate for studies on the relations of species composition and richness with climatic *** show that species sampling completeness of GBIF is low(lude that fern species lists derived from GBIF are generally very incomplete across a wide range of spatial scales,and are not appropriate for studies that require data derived from species lists in high *** present a map showing global patterns of fern species diversity based on complete or nearly complete regional fern species lists.

关键词： Climate Data bias Fern GBIF Species diversity Species list

Energy-Efficient Optimal Guaranteed Cost Intermittent-Switch Control of a Direct Expansion Air Conditioning System

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IEEE/CAA Journal of Automatica Sinica 2021年第11期8卷 1852-1866页

作者： Jun mei Zhenyu lu Junhao Hu Yuling Fan School of Mathematics and Statistics South-Central University for NationalitiesWuhan 430074China School of Electronic and Information Engineering Nanjing University of Information Science and TechnologyNanjing 210044China College of Informatics Huazhong Agricultural UniversityWuhan 430072China

To improve the energy efficiency of a direct expansion air conditioning(DX A/C) system while guaranteeing occupancy comfort, a hierarchical controller for a DX A/C system with uncertain parameters is proposed. The control strategy consists of an open loop optimization controller and a closed-loop guaranteed cost periodically intermittent-switch controller(GCPISC). The error dynamics system of the closed-loop control is modelled based on the GCPISC principle. The difference,compared to the previous DX A/C system control methods, is that the controller designed in this paper performs control at discrete times. For the ease of designing the controller, a series of matrix inequalities are derived to be the sufficient conditions of the lower-layer closed-loop GCPISC controller. In this way, the DX A/C system output is derived to follow the optimal references obtained through the upper-layer open loop controller in exponential time, and the energy efficiency of the system is improved. Moreover, a static optimization problem is addressed for obtaining an optimal GCPISC law to ensure a minimum upper bound on the DX A/C system performance considering energy efficiency and output tracking error. The advantages of the designed hierarchical controller for a DX A/C system with uncertain parameters are demonstrated through some simulation results.

关键词： Energy efficiency hierarchical control open loop optimal control optimal guaranteed cost periodically intermittent-switch control