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Exploration of reaction rates of chlorine dioxide with tryptophan residue in oligopeptides and proteins

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Journal of Environmental Sciences 2020年第7期32卷 129-136页

作者： Yuexian Ge Yu lei xin lei Wenhui Gan Longfei Shu xin Yang School of Environmental Science and Engineering Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation TechnologySun Yat-sen UniversityGuangzhou 510275China Graduate School at Shenzhen Tsinghua UniversityShenzhen 518055China

Chlorine dioxide(ClO2),an alternative disinfectant to chlorine,has a superior ability to inactivate microorganisms,in which protein damage has been considered as the main inactivation ***,the reactivity of ClO2 with amino acid residues in oligopeptides and proteins remains poorly *** this research,we studied the reaction rate constants of ClO2 with tryptophan residues in five heptapeptides and four proteins using stopped-flow or competition kinetic *** heptapeptide and protein contain only one tryptophan residue and the reactivity of tryptophan residue with ClO2 was lower than that of free tryptophan(3.88×10^4(mol/L)^-1 sec^-1 at pH 7.0).The neighboring amino acid residues affected the reaction rates through promoting inter-peptide aggregation,changing electron density,shifting pKa values or inducing electron transfer via redox reactions.A single amino acid residue difference in oligopeptides can make the reaction rate constants differ by over 60%(e.g.3.01×10^4(mol/L)^-1 sec^-1 for DDDWNDD and 1.85×10^4(mol/L)^-1 sec^-1 for DDDWDDD at pH 7.0(D:aspartic acid,W:tryptophan,N:asparagine)).The reaction rates of tryptophan-containing oligopeptides were also highly pH-dependent with higher reactivity for deprotonated tryptophan than the neutral *** residues in proteins spanned a 4-fold range reactivity toward ClO2(i.e.0.84×10^4(mol/L)^-1 sec^-1 for ribonuclease T1 and 3.21×10^4(mol/L)^-1 sec^-1 for melittin at pH 7.0)with accessibility to the oxidant as the determinating *** local environment surrounding the tryptophan residue in proteins can also accelerate the reaction rates by increasing the electron density of the indole ring of tryptophan or inhibit the reaction rates by inducing electron transfer *** results are of significance in advancing understanding of ClO2 oxidative reactions with proteins and microbial inactivation mechanisms.

关键词： Chlorine dioxide(ClO2) Tryptophan Protein Disinfection Water treatment

Aerodynamic stability of cable-supported bridges using CFRP cables

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第5期8卷 693-698页

作者： ZHANG xin-jun YING lei-dong College of Civil Engineering and Architecture Zhejiang University of Technology Hangzhou 310014 China

To gain understanding of the applicability of carbon fiber reinforced polymer (CFRP) cable in cable-supported bridges, based on the Runyang Bridge and Jinsha Bridge, a suspension bridge using CFRP cables and a cable-stayed bridge using CFRP stay cables are designed, in which the cable’s cross-sectional area is determined by the principle of equivalent axial stiffness. Numerical investigations on the aerodynamic stability of the two bridges are conducted by 3D nonlinear aerodynamic stability analysis. The results showed that as CFRP cables are used in cable-supported bridges, for suspension bridge, its aerodynamic stability is superior to that of the case using steel cables due to the great increase of the torsional frequency; for cable-stayed bridge, its aerodynamic stability is basically the same as that of the case using steel stay cables. Therefore as far as the wind stability is considered, the use of CFRP cables in cable-supported bridges is feasible, and the cable’s cross-sectional area should be deter-mined by the principle of equivalent axial stiffness.

关键词： Cable-supported bridges Carbon fiber reinforced polymer (CFRP) cable Aerodynamic stability

Tailoring magnetostriction and magnetic domains of <100>-oriented Fe80Ga16Al4 alloy by magnetic field annealing

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Rare Metals 2021年第3期40卷 563-569页

作者： xin-lei Wang Yuan Liu Xiang Chen School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of Education Beijing 100084China

Magnetic field annealing(MFA) was used to tailor the magnetostriction and magnetic domains of Fe80Ga16Al4 alloy,and the relationship between the two characteristics was *** -oriented alloy was prepared by the directional solidification technique and annealed for 20 min at 700℃ in a magnetic field of 250 mT along a direction 45 ° to the orientation,followed by furnace cooling in the same magnetic *** magnetostriction along the length direction(λ‖),the width direction(λ丄) and the saturation magnetostriction(λs) was changed from λ‖=208 × 10^(-6) and λ丄=-16 × 10^(-6) of the initial alloy to λ‖≈λ丄≈ 1/2 λs ≈ 112 × 10^(-6)after *** magnetic domain structure,which mainly refers to the number,size,and direction of the domains,was tailored and rearranged by *** rearrangement of the magnetic domain structure resulted in a shift of magnetostrictive properties parallel and perpendicular to the orientation for the Fe80Ga16A14 *** magnetic field annealing method can aid understanding of the relationship between the microscopic magnetic domains and the macroscopic magnetostrictive *** can also aid in further tailoring better magnetostrictive properties within magnetostrictive materials to meet the requirements of different application conditions.

关键词： FeGa alloy Magnetic field annealing Magnetostriction Magnetic domain

TRPIV investigation of space-time correlation in turbulent flows over flat and wavy walls

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Acta Mechanica Sinica 2014年第4期30卷 468-479页

作者： Wei Wang xin-lei Guan Nan Jiang Department of Mechanics Tianjin University Tianjin Key Laboratory of Modern Engineering Mechanics The State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences

The present experimental work is devoted to in- vestigate a new space-time correlation model for the turbulent boundary layer over a flat and a wavy walls. A turbulent boundary layer flow at Reo = 2460 is measured by tomographic time-resolved particle image velocimetry （Tomo-TRPIV）. The space-time correlations of instantaneous streamwise fluctuation velocity are calculated at 3 different wall-normal locations in logarithmic layer. It is found that the scales of coherent structure increase with moving far away from the wall. The growth of scales is a manifestation of the growth of prevalent coherent structures in the turbulent boundary layer like hairpin vortex or hairpin packets when they lift up. The resulting contours of the space-time correlation exhibit elliptic-like shapes rather than straight lines. It is suggested that, instead of Taylor hypothesis, the elliptic model of the space-time correlation is valid for the wallbounded turbulent flow over either a flat wall or a wavy wall. The elliptic iso-correlation curves have a uniform preferred orientation whose slope is determined by the convection velocity. The convection velocity derived from the space-time correlation represents the velocity at which the large-scale eddies carry small-scale eddies. The sweep velocity rep- resents the distortions of the small-scale eddies and is intimately associated with the fluctuation velocity in the logarithmic layer of turbulent boundary layers. The nondimensionalized correlation curves confirm that the elliptic model is more proper for approximating the space-time correlation than Taylor hypothesis, because the latter can not embody the small-scale motions which have non-negligible distortions. A second flow over a wavy wall is also recorded using TRPIV. Due to the combined effect of shear layers and the adverse pressure gradient, the space-time correlation does not show an elliptic-like shape at some specific heights over the wavy wall, but in the outer region of the wav

关键词： Tomographic particle image velocimetry Tur-bulent boundary layer Wavy wall Space-time correlation Taylor hypothesis Elliptic model

Porous hydrogel arrays for hepatoma cell spheroid formation and drug resistance investigation

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Bio-Design and Manufacturing 2021年第4期4卷 842-850页

作者： xin lei Changmin Shao xin Shou Keqing Shi Liang Shi Yuanjin Zhao Translational Medicine Laboratory The First Affiliated Hospital of Wenzhou Medical UniversityWenzhou 325035China Wenzhou Institute University of Chinese Academy of SciencesWenzhou 325001China State Key Laboratory of Bioelectronics School of Biological Science and Medical EngineeringSoutheast UniversityNanjing 210096China Department of Laboratory Medicine The Eighth Affiliated HospitalSun Yat-Sen UniversityShenzhen 518033China

Drug resistance is one of the major obstacles in the drug therapy of *** in this area in pre-clinical research have focused on developing novel platforms to evaluate and decrease drug *** this paper,inspired by the structure of hives where swarms live and breed,we propose porous hydrogel arrays with a uniform pore structure for the generation of hepatoma cell spheroids and the investigation of drug *** porous hydrogel arrays were fabricated using polyeth-ylene glycol diacrylate(PEGDA)hydrogel to negatively replicate a well-designed *** from the elaborate processing of the template,the prepared porous hydrogel arrays possessed a uniform pore *** to their anti-adhesion properties and the excellent biocompatibility of the PEGDA hydrogel,the hepatoma cells could form well-defined and uni-form hepatoma cell spheroids in the porous hydrogel *** found that the resistant hepatoma cell spheroids showed more significant Lenvatinib resistance and a migratory phenotype compared with a two-dimensional(2D)cell culture,which reveals the reason for the failure of most 2D cell-selected drugs for in vivo *** features give such porous hydrogel arrays promising application prospects in the investigation of tumor cell spheroid culture and in vitro drug resistance.

关键词： Drug resistance Hydrogel Porous Spheroid Hepatoma

HYDRAULIC PRESSURE SIGNAL DENOISING USING THRESHOLD SELF-LEARNING WAVELET ALGORITHM

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Journal of Hydrodynamics 2008年第4期20卷 433-439页

作者： GUO xin-lei YANG Kai-lin GUO Yong-xin Department of Hydraulics China Institute of Water Resources and Hydropower Research Beijing 100044 China

A pre-filter combined with threshold self-learning wavelet algorithm is proposed for hydraulic pressure signals denoising. The denoising threshold is self-learnt in the steady flow state, and then modified under a given limit to make the mean square errors between reconstruction signals and desirable outputs minimum, so the corresponding optimal denoising threshold in a single operating case can be obtained. These optimal thresholds are used for the whole signal denoising and are different in various cases. Simulation results and comparative studies show that the present approach has an obvious effect of noise suppression and is superior to those of traditional wavelet algorithms and back-propagation neural networks. It also provides the precise data for the next step of pipeline leak detection using transient technique.

关键词： hydraulic pressure signal wavelet threshold denoising self-learning neural network

Ultrathin 2D Conjugated Polymer Nanosheets for Solar Fuel Generation

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Chinese Journal of Polymer Science 2019年第2期37卷 101-114页

作者： xin-lei Zhang lei Wang Liang Chen Xiao-Yu Ma Hang-Xun Xu Chinese Academy of Sciences Key Laboratory of Soft Matter Chemistry Department of Polymer Science and Engineering Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China

Two-dimensional(2 D) polymers are fascinating as they exhibit unique physical, chemical, mechanical, and electronic properties that are completely different from those of traditional linear or branched polymers. They are very promising for applications in catalysis, separation, optoelectronics, energy storage, and nanomedicine. Recently, ultrathin 2 D conjugated polymers have emerged as advanced materials for converting solar energy into chemical energy. The inherent 2 D planar structure with in-plane periodicity offers many features that are highly desirable for photon-involved catalytic energy conversion processes, including high absorption coefficients,large surface areas, abundant surface active sites, and efficient charge separation. Moreover, the possibility of finely tuning the optoelectronic and structural properties through precise molecular engineering has opened up new opportunities for design and synthesis of novel 2 D polymer nanosheets with unprecedented applications. Herein, we highlight recent advances in developing ultrathin 2 D conjugated polymer nanosheets for solar-to-chemical energy conversion. Specifically, we discuss emerging applications of ultrathin 2 D conjugated polymer nanosheets for solar-driven water splitting and CO2 reduction. Meanwhile, future challenges and prospects for design and synthesis of ultrathin 2 D conjugated polymer nanosheets for solar fuel generation are also included.

关键词： 2D polymers Conjugated polymers Nanosheets Photocatalysis Energy conversion

A study on coherent structures and drag-reduction in the wall turbulence with polymer additives by TRPIV

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Acta Mechanica Sinica 2013年第4期29卷 485-493页

作者： xin-lei Guan Shi-Yong Yao Nan Jiang Department of Mechanics Tianjin University Tianjin Key Laboratory of Modern Engineering Mechanics The State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Nankai University-Tianjin University Center for Liu Hui Applied Mathematics

An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer additive solu- tion. The fully developed near-wall turbulent flow fields with and without polymer additives at the same Reynolds number were measured by TRPIV in a water channel. The compar- isons of turbulent statistics confirm that due to viscoelastic structure of long-chain polymers, the wall-normal velocity fluctuation and Reynolds shear stress in the near-wall region are suppressed significantly. Furthermore, it is noted that such a behavior of polymers is closely related to the decease of the motion of the second and forth quadrants, i.e., the ejection and sweep events, in the near-wall region. The spa- tial topological mode of coherent structures during bursts has been extracted by the new mu-level criteria based on locally averaged velocity structure function. Although the general shapes of coherent structures are unchanged by polymer additives, the fluctuating velocity, velocity gradient, velocity strain rate and vorticity of coherent structures during burst events are suppressed in the polymer additive solution com- pared with that in water. The results show that due to the polymer additives the occurrence and intensity of coherent structures are suppressed, leading to drag reduction.

关键词： Time-resolved particle image velocimetry ~ Wall-bounded turbulence ~ Coherent structures ~ Polymer addi-tives ~ Drag reduction

Tension and Drag Forces of Flexible Risers Undergoing Vortex-Induced Vibration

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China Ocean Engineering 2017年第1期31卷 1-10页

作者： SONG lei-jian FU Shi-xiao LI Man GAO Yun MA lei-xin State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Shanghai 200240China Marine Design & Research Institute of China Shanghai 200011China State Key Laboratory of Oil and Gas Reservoir Geology and Exploration Southwest Petroleum UniversityChengdu 610500China

This paper presents the results of an experimental investigation on the variation in the tension and the distribution of drag force coefficients along flexible risers under vortex-induced vibration（VIV） in a uniform flow for Reynolds numbers（Re） up to 2.2×10^5. The results show that the mean tension is proportional to the square of the incoming current speed, and the tension coefficient of a flexible riser undergoing VIV can be up to 12. The mean drag force is uniformly and symmetrically distributed along the axes of the risers undergoing VIV. The corresponding drag coefficient can vary between 1.6 and 2.4 but is not a constant value of 1.2, as it is for a fixed cylinder in the absence of VIV. These experimental results are used to develop a new empirical prediction model to estimate the drag force coefficient for flexible risers undergoing VIV for Reynolds number on the order of 10^5, which accounts for the effects of the incoming current speed, the VIV dominant modal number and the frequency.

关键词： Reynolds riser cylinder vortex Vortex hydrodynamic empirical turbulent averaged oscillating