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Preparation of glucosamine by hydrolysis of chitosan with commercial α-amylase and glucoamylase

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2011年第11期12卷 931-934页

作者： Sai-kun PAN Sheng-jun WU jin-moon KIM Jiangsu Key Laboratory of Marine Biotechnology Huaihai Institute of Technology Lianyungang 222005 China School of Marine Science and Technology Huaihai Institute of Technology Lianyungang 222005 China Food Safety and Inspection Service Office of Field Operations US Department of Agriculture Albany iVY 12203 USA

Objective： In order to overcome the defects of chemical hydrolysis approach to prepare glucosamine, an enzymatic hydrolysis method was developed. Methods： Glucosamine was prepared by hydrolyzing chitosan, em- ploying e-amylase initially, and subsequently, glucoamylase. Results： The optimal hydrolyzing conditions were as follows： reaction time, 4 h; pH, 5.0; temperature, 50 ℃; and, α-amylase, 80 U/g for the initial reaction. Subsequently, glucoamylase was added in the presence of a-amylase. The optimal reaction conditions were found to be： reaction time, 8 h; pH, 4.5; temperature, 55 ℃; and, glucoamylase, 4000 U/g. The hydrolysates were subject to filtrating, concentrating to about 20% （w/w）, precipitating with five volumes of ethanol, and drying at 60 ℃ for 2 h. The content and the yield of glucosamine in the dried precipitate were 91.3% （w/w） and 86.2% （w/w）, respectively. Conclusions： The method developed in this study is a promising option in the preparation of glucosamine.

关键词： Glucosamine o-Amylase Glucoamylase Hydrolysis

Synthesis and characterization of biodegradable amphiphilic PEG-grafted poly(DTC-co-CL)

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Chinese Chemical Letters 2010年第10期21卷 1255-1258页

作者： Qiu jin Zhang Wei Pu Zhu Zhi Quan Shen MOE Key Laboratory of Macromolecule Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China

A novel biodegradable copolymer, poly（5,5-dibromomethyltrimethylene carbonate-co-ε-caprolactone）（poly（DBTC-co-CL）） with pendant bromine groups, was synthesized via ring-opening polymerization （ROP） of ε-caprolactone （CL） and 5,5- dibromomethyltrimethylene carbonate （DBTC） using stannous octoate （Sn（Oct）2） as catalyst. Then the pendant bromine groups were completely converted into azide form, which permitted ＂click＂ reaction with alkyne-terminated polyethylene （A-PEG） by Huisgen 1,3-dipolar cycloadditions preparing biodegradable amphiphilic poly（DTC-co-CL）-g-PEG graft copolymer. The graft copolymer was characterized by nuclear magnetic resonance （NMR） and size-exclusion chromatography （SEC）.

关键词： Polycarbonate "Click" reaction Graft copolymer Ring-opening polymerization

Tissue specific prediction of N^(6)-methyladenine sites based on an ensemble of multi-input hybrid neural network

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BIOCELL 2022年第4期46卷 1105-1121页

作者： CANGZHI JIA DONG jin XIN WANG QI ZHAO School of Science Dalian Maritime UniversityDalian116026China School of Computer Science and Software Engineering University of Science and Technology LiaoningAnshan114051China

N^(6)-Methyladenine is a dynamic and reversible post translational modification,which plays an essential role in various biological *** of the current inability to identify m6A-containing mRNAs,computational approaches have been developed to identify m6A sites in DNA *** to improve prediction performance,we introduced a novel ensemble computational approach based on three hybrid deep neural networks,including a convolutional neural network,a capsule network,and a bidirectional gated recurrent unit(BiGRU)with the self-attention mechanism,to identify m6A sites in four tissues of three *** a total of 11 datasets,we selected different feature subsets,after optimized from 4933 dimensional features,as input for the deep hybrid neural *** addition,to solve the deviation caused by the relatively small number of experimentally verified samples,we constructed an ensemble model through integrating five sub-classifiers based on different training *** compared through 5-fold cross-validation and independent tests,our model showed its superiority to previous methods,im6A-TS-CNN and iRNA-m6A.

关键词： M6A sites Deep hybrid neural networks Ensemble model Feature selection

Constitutive Model for F45V Microalloyed Forging Steel at High Temperature

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Journal of Iron and Steel Research International 2014年第4期21卷 464-468页

作者： jin WANG Wen-long MA Zhong CHU Qi ZHANG Department of Mechanical Engineering Qingdao Technological University

Isothermal hot compression experiments of F45V, a microalloyed steel, were performed on a Gleeble-1500 thermo-mechanical simulator at temperatures of 950--1200 ;C and strain rate of 0.01--10 s -1. Based on the experi- mental flow stress curves, a constitutive model that was expressed by the hyperbolic laws in an Arrhenius-type equa- tion was established, and the material parameters of the model were expressed as 6th order polynomial form of strain. Standard statistical parameters such as correlation coefficient and average absolute relative error were em- ployed to quantify the predictability of the model. They were found to be 0. 995 and 4.34% respectively. The results show that the established constitutive mode[ can predict the magnitude and tendency of flow stress with the increase of deformation accurately, and can be used for the numerical simulation of hot forging process of the F45V steel.

关键词： F45V steel microalloyed forging steel flow stress Arrhenius equation constitutive model

Lie group classification of the N-th-order nonlinear evolution equations

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Science China Mathematics 2011年第12期54卷 2553-2572页

作者： SHEN ShouFeng QU ChangZheng HUANG Qing jin YongYang Department of Applied Mathematics Zhejiang University of Technology Hangzhou 310023 China Department of Mathematics Ningbo University Ningbo 315211 China Department of Mathematics Northwest University Xi＇an 710069 China

In this paper, Lie group classification to the N-th-order nonlinear evolution equation Ut ： UNx ＋ F（x, t, u, ux, . . . , U（N-1）x）is performed. It is shown that there are three, nine, forty-four and sixty-one inequivalent equations admitting one-, two-, three- and four-dimensionM solvable Lie algebras, respectively. We also prove that there are no semisimple Lie group 50（3） as the symmetry group of the equation, and only two realizations oral（2, R） are admitted by the equation. The resulting invariant equations contain both the well-known equations and a variety of new ones.

关键词： group classification Lie algebra nonlinear evolution equation

A new depsidone from Usnea diffracta

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Chinese Chemical Letters 2009年第2期20卷 187-189页

作者： Huan Yang Qi Yuan Peng jin Yan Ping Shi Key Laboratory for Natural Medicine of Gansu Province Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou 730000 China

A new depsidone, diffractione A （1）, as well as six known phenolic compounds （2-7） were isolated from Usnea diffracta. Their structures were elucidated by 1D and 2D NMR spectroscopy together with HRESIMS analysis.... 详细信息

关键词： Depsidone Usneaceae Usnea diffracta Lichen Diffractione A

Electrochemical Determination of Phenylethanolamine A Based on Nafion/MWCNTs/AuNPs Modified Carbon Electrode

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Chinese Journal of Chemistry 2013年第2期31卷 221-229页

作者： Yanjun Lai jing Bai Wei Zhu Yuezhong Xian Litong jin Department of Chemistry East China Normal University Shanghai 200062 China Institute of Quality Inspection of Food and Cosmetics Shanghai institute of Quality Inspection and Technical Research Shanghai 200233 China

Phenylethanolamine A （PEA）, a fl-agonist, was found to be illegally used as a growth promoter in pigs last year, causing Chinese government＇s great attention. Here, a sensitive electrochemical method was developed for detecting PEA by immobilization of gold nanoparticles （AuNPs）, multiwalled carbon nanotubes （MWCNTs） and Nation on the surface of a glassy carbon electrode （GCE）. The Nafion/MWCNTs/AuNPs film was characterized by scanning electronic micrographs （SEM） and electrochemical impedance spectroscopy （EIS）. The electrochemical behaviors of PEA at the modified GCE were investigated in detail. The synergetic effects of AuNPs, MWCNTs and Nation amplify the electrochemical reduction signal of PEA, and result in high sensitivity for PEA determination. Under the optimal conditions, the electrochemical sensor shows a wide linear range of 0.01 to 10 μmol/L with a detection limit of 0.005μmol/L. Moreover, the fabricated sensor presents high selectivity and long-term stability, which paves a new way for simple, rapid, sensitive detection of PEA.

关键词： electrochemistry detection nanoparticles phenylethanolamine A

Time Lags between the 22 and 37 GHz Bursts of 48 Radio-loud AGNs

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Chinese Journal of Astronomy and Astrophysics 2008年第2期8卷 195-203页

作者： Wen-Guo Deng jin-Ming Bai Li Zhang Xian Yang National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 650011 Physics Department Yunnan University Kunming 650091

Based on the light curves at 22 and 37 GHz from the Metsahovi monitoring program, we investigate the time lags between the two radio bands for 48 radio-loud AGNs. DCF and ZDCF analyses are applied to the data. Our results show that there is a strong correlation between the two radio frequencies for all the sources, with the variations in the light curves at 37 GHz leading the ones at 22 GHz in general. There is no obvious differences between different sub-class AGNs as regards the time lag. In two sources, it was found that the bursts at the lower frequency lead the ones at the higher frequency. One possible explanation is that electron acceleration dominates the light curve until the radiation reaches the maximum. Some sources, such as 3C 273, 3C 279, 3C 345 and 3C 454.3, have good enough data, so we can calculate their lags burst-by-burst. Our calculations show that different outbursts have dif- ferent lags. Some bursts have positive lags, most of bursts have no clear lags, and a few have negative lags. This result means that different bursts are triggered by different mechanisms, and the interpretation for the result involves both an intrinsic and a geometric mechanism. The positive lags are well consistent with the shock model, and we use these lags to calculate the typical magnetic field strength of the radiating region.

关键词： galaxies: active -- galaxies: individual (3C 273 3C 279 3C 345 3C 454.3) --methods: data analysis

Novel Balun Structure for Dipole Antenna

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Transactions of Nanjing University of Aeronautics and Astronautics 2017年第5期34卷 561-566页

作者： jin Kui Zhang Enze Yang Yang He Xiaoxiang Gu Changqing College of Electronic Information Engineering Nanjing University of Aeronautics and Astronautics Ministerial Key Laboratory of JGMT Nanjing University of Science and Technology

A novel balun structure for dipole antenna,which is based on the current distribution on parallel microstrip lines and the emission cancellation characteristic of close equal and opposite currents,is *** principle of the balun structure is first elaborated and ***,a dipole antenna with resonance at 2.45 GHz is constructed using the balun and its radiation pattern is *** simulated and measured reflection coefficients(S_(11))of the antenna are in good agreement 2—3 *** relative bandwidth with an S_(11) of below-10 dB is more than 25%.The antenna also shows a good radiation pattern at 2.45 *** proposed structure can provide a new balun design method for dipole antennas.

关键词： coplanar balun dipole antenna wideband compact balun