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Preparation of Semi-interpenetrating Polymer Network of Silicon Rubber and Poly(methyl methylacrylate) Using Supercritical CO_2

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Chinese Chemical Letters 2002年第7期13卷 683-684页

作者： Zhi min liu jia Qiu WANG Guan Ying YANG Bu Xing HAN Center for molecular sciences Institute of ChemistryChinese Academy of SciencesBeijing 100080

The heterogeneous free-radical polymerization of methyl methylacrylate (MMA) and divinylbenzene (DVB) as cross-linker within supercritical carbon dioxide-swollen silicon rubber (SR) has been studied as an approach to preparing semi-interpenetrating polymer network (semi-IPN) of SR and poly(methyl methylacrylate) (PMMA). The SR/PMMA semi-IPNs were characterized by scanning electron microscopy (SEM) and dynamic mechanical analyzer (DMA).

关键词： Supercritical CO2 interpenetrating polymer network silicon rubber poly(methyl methylacrylate) polymerization.

Analysis of expression and chitin-binding activity of the wing disc cuticle protein BmWCP4 in the silkworm, Bombyx moil

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Insect Science 2016年第6期23卷 782-790页

作者： Hui-min Deng Yong Li jia-Ling Zhang Lin liu Qi-Li Feng Guangzhou Key Laboratory of Insect Development Regulation and Application Research School of Life Sciences South China Normal University Guangzhou 510631 China

The insect exoskeleton is mainly composed of chitin filaments linked by cuticle proteins. When insects molt, the cuticle of the exoskeleton is renewed by degrading the old chitin and cuticle proteins and synthesizing new ones. In this study, chitin-binding activity of the wing disc cuticle protein BmWCP4 in Bombyx mori was studied. Sequence analysis showed that the protein had a conservative hydrophilic ＂R＆R＂ chitin-binding domain （CBD）. Western blotting showed that BmWCP4 was predominately expressed in the wing disc-containing epidermis during the late wandering and early pupal stages. The immunohistochemistry result showed that the BmWCP4 was mainly present in the wing disc tissues containing wing bud and trachea blast during day 2 of wandering stage. Recombinant full-length BmWCP4 protein, ＂R＆R＂ CBD peptide （CBD）, non-CBD peptide （BmWCP4-CBD^-）, four single site-directed mutated peptides （M1, M2, M3 and M4） and four-sites-mutated peptide （MF） were generated and purified, respectively, for in vitro chitin-binding assay. The results indicated that both the full-length protein and the ＂R＆R＂ CBD peptide could bind with chitin, whereas the BmWCP4-CBD- could not bind with chitin. The single residue mutants M1, M2, M3 and M4 reduced but did not completely abolish the chitin-binding activity, while four-sites-mutated protein MF completely lost the chitin-binding activity. These data indicate that BmWCP4 protein plays a critical role by binding to the chitin filaments in the wing during larva-to-pupa transformation. The conserved aromatic amino acids are critical in the interaction between chitin and the cuticle protein.

关键词： Bombyx mori chitin chitin binding cuticle protein wing disc

Synthesis and Characterization of Specific Haptens Used to Generate Abzyme with Glutathione Peroxidase Activity

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Chemical Research in Chinese Universities 1998年第3期14卷 55-57页

作者： liu Jun-qiu Gao Shu-juan Luo Gui-min Shen jia-cong The National Laboratory of Enzyme Engineering Key Laboratory for Supermolecular Spectra and Structure of Jilin UniversityJinlin UniversityChangchun130023

Glutathione was modified selectively by 2,4 dinitrochlorobenzene,giving S substituted dinitrophenyl glutathione(GSH S DNP).GSH S DNP was further esterified by iso butanol,hexanol,cyclohexanol and benzyl *** haptens used to generate abzyme with glutathione peroxidase(GPX)activity were *** are GSH DNP biesters:GSH DNP di iso butyl ester(GSH DNP IBU),GSH DNP bihexyl ester(GSH DNP HE),GSH DNP bicyclohexyl ester(GSH DNP CH),GSH DNP bibenzylmethyl ester(GSH DNP BE).The structures of the haptens were characterized by means of elemental analysis,IR and 1H NMR.

关键词： Glutathione peroxidase Abzyme Hapten

Some Sufficient Conditions for Convergent Multivariate Subdivision Schemes with Nonnegative Finite Masks

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Acta Mathematica Sinica,English Series 2012年第7期28卷 1411-1420页

作者： min WU jia Li ZHOU Department of Mathematics Zhejiang University of Science and Technology Department of Mathematics Zhejiang University of Technology

It is well known that the convergence of multivariate subdivision schemes with finite masks can be characterized via joint spectral radius. For nonnegative masks, we will present in this paper some computable simply s... 详细信息

关键词： Cascade algorithm dilation equation joint spectral radius mask subdivision scheme

Prediction model of volume average diameter and analysis of atomization characteristics in electrostatic atomization minimum quantity lubrication

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Friction 2023年第11期11卷 2107-2131页

作者： Dongzhou jia Changhe LI jiahao liu Yanbin ZHANG min YANG Teng GAO Zafar SAID Shubham SHARMA School of Mechanical&Automotive Engineering Qingdao University of TechnologyQingdao 266520China College of Mechanical Engineering and Automation Liaoning University of TechnologyJinzhou 121001China State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHong Kong 999077China College of Engineering University of SharjahSharjah 27272United Arab Emirates Mechanical Engineering Department University Center for Research and DevelopmentChandigarh UniversityMohaliPunjab 144603India

minimum quantity lubrication(MQL)is a relatively efficient and clean alternative to flooding workpiece *** atomization has the merits of small droplet diameter,high uniformity of droplet size,and strong coating,hence its superiority to pneumatic ***,as the current research hotspot,the influence of jet parameters and electrical parameters on the average diameter of droplets is not ***,by observing the shape of the liquid film at the nozzle outlet,the influence law of air pressure and voltage on liquid film thickness(h)and transverse and longitudinal fluctuations are ***,the mathematical model of charged droplet volume average diameter(VAD)is constructed based on three dimensions of the liquid film,namely its thickness,transverse wavelength(λ_(h)),and longitudinal wavelength(λ_(z)).The model results under different working conditions are obtained by numerical *** of the model results with the experimental VAD of the droplet confirm the error of the mathematical model to be less than 10%.The droplet diameter distribution span value Rosin–Rammler distribution span(R.S)and percentage concentrations of PM10(particle size of less than 10μm)/PM2.5(particle size of less than 2.5μm)under different working conditions are further *** results show that electrostatic atomization not only reduces the diameter distribution span of atomized droplets but also significantly inhibits the formation of PM10 and PM2.5 fine-suspension *** the air pressure is 0.3 MPa,and the voltage is 40 kV,the percentage concentrations of PM10 and PM2.5 can be reduced by 80.72%and 92.05%,respectively,compared with that under the pure pneumatic atomization condition at 0.3 MPa.

关键词： minimum quantity lubrication(MQL) electrostatic atomization volume average diameter(VAD) atomization characteristics

Novel backstepping design for blended aero and reaction-jet missile autopilot

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Journal of Systems Engineering and Electronics 2008年第1期19卷 148-153页

作者： liu Zhong jia Xiaohong Opto-Electro Technology Development Center Luoyang 471009 P.R. China

The advanced missile uses blended control of nero-fin and reaction-jet to improve missile maneuverability. The blended control design, which is multi-inputs and multi-outputs （MIMO）, severe nonlinear, and model uncertain, is much more complex than conventional nero-fin control. A novel nonlinear backstepping control approach is proposed to design the blended autopilot. Missile model is reformed to a new one by state reconstruction technique so that it is easy to be handled by the backstepping method. Then a Lyapunov function is chosen to avoid oscillation caused in normal backstepping way when control parameters are mismatched. In distribution of both inputs, optimal energy logic is proposed. In addition, a fuzzy cerebellar model articulation controller （FCMAC） neural network is used to guarantee controller robustness to uncertainties. Finally, simulation results demonstrate the efficiency and advantages of the proposed method.

关键词： missile control blended aero-fin and reaction-jet control nonlinear backstepping optimal enery logic.

Effect of Low-temperature Imidization on Properties and Aggregation Structures of Polyimide Films with Different Rigidity

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Chinese Journal of Polymer Science 2024年第8期42卷 1134-1146页

作者： Yan jia Lei Zhai Song Mo Yi liu Li-Xin liu Xin-Yu Du min-Hui He Lin Fan Key Laboratory of Science and Technology on High-tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

The traditional high-temperature preparation process of polyimide can cause many problems and limits the wider application in extreme *** important challenge to be solved urgently is the reduction of imidization *** this work,twelve kinds of polyimide films with different chain rigidity were prepared at low temperature of 200℃,in the absence or presence of imidazole used as the *** molecular rigidity and free volume were theoretically calculated,and relationship between structure and properties were systematically *** results show that imidization reaction under low temperatures is significantly affected by the rigidity of molecula r *** rigid structure of polyimide is not conducive to the low-temperature imidization,but this adverse effect can be eliminated by adding catalyst,resulting the notably increased imidization *** optical and thermal properties can be improved to a certain extent for the chemically catalyzed system,resulting in relatively higher heat resistance and thermal *** the mechanical performance could be determined by com plicating factors,greatly different from polyimide films prepa red by high temperature *** investigate aggregation structures of film s,the effect of chain rigidity and catalyst on the stacking or orientation of molecular chains was further *** wo rk can contribute to the understanding of chemically catalyzed imidization that is rarely reported in the existing research,and will provide guidance for the low-temperature preparation of high-performance polyimides.

关键词： Polyimide Imidization Catalyst Structure and properties Aggregation structures

Thermally Conductive Polyimide/Boron Nitride Composite Films with Improved Interfacial Compatibility Based on Modified Fillers by Polyimide Brushes

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Chinese Journal of Polymer Science 2023年第12期41卷 1921-1936,I0009页

作者： Meng-Yan Gao Lei Zhai Song Mo Yan jia Yi liu min-Hui He Lin Fan Key Laboratory of Science and Technology on High-tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

Polyimide-based composite films with high thermal conductivity,good mechanical property and electrical insulating performance are urgently needed in the electronics and microelectronics *** one of the key technical challenges to be solved,interfacial compatibility between filler and matrix plays an important role for composite ***,boron nitride was modified by grafting polyimide brushes via a twostep method,and a series of thermally conductive polyimide/boron nitride composite films were *** characterization and performance results proved that the interfacial interaction and compatibility was greatly enhanced,resulting in a significant reduction in defects and interfacial thermal *** interphase width of transition zone between two phases was also efficiently enlarged due to polyimide brushes grafted on filler *** a result,composite films based on polyimide-grafted boron nitride exhibited significantly improved properties compared with those based on pristine *** strength can reach up to 80 MPa even if the filler content is as high as 50 wt%.The out-of-plane and in-plane thermal conductivity of composite film increased to 0.841 and 0.850 W·m^(-1)·K^(-1),*** addition,thermal and dielectric properties of composite films were also enhanced to some *** above results indicate that surface modification by chemically grafting polymer brushes is an effective method to improve two-phase interfacial compatibility so as to prepare composite film with enhanced properties.

关键词： Polyimide Composite film Boron nitride Thermal conductivity Interfacial compatibility

Computational Study of the Effects of Shroud Geometric Variation on Turbine Performance in a 1.5-Stage High-Loaded Turbine

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Journal of Thermal Science 2013年第5期22卷 439-446页

作者： Wei jia Huoxing liu National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power Engineering Beihang University

Generally speaking, main flow path of gas turbine is assumed to be perfect for standard 3D computation. But in real engine, the turbine annulus geometry is not completely smooth for the presence of the shroud and associated cavity near the end wall. Besides, shroud leakage flow is one of the dominant sources of secondary flow in tur- bomachinery, which not only causes a deterioration of useful work but also a penalty on turbine efficiency. It has been found that neglect shroud leakage flow makes the computed velocity profiles and loss distribution signifi- cantly different to those measured. Even so, the influence of shroud leakage flow is seldom taken into considera- tion during the routine of turbine design due to insufficient understanding of its impact on end wall flows and tur- bine performance. In order to evaluate the impact of tip shroud geometry on turbine performance, a 3D computa- tional investigation for 1.5-stage turbine with shrouded blades was performed in this paper. The following ge- ometry parameters were varied respectively：

关键词： labyrinth seal tip shroud geometry shroud leakage flow turbine performance high-loaded turbine