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101.
We previously showed that vaccinia virus infection of BSC40 cells was blocked by soluble heparin, suggesting that cell surface heparan sulfate mediates vaccinia virus binding (C.-S. Chung, J.-C. Hsiao, Y. -S. Chang, and W. Chang, J. Virol. 72:1577-1585, 1998). In this study, we extended our previous work and demonstrated that soluble A27L protein bound to heparan sulfate on cells and interfered with vaccinia virus infection at a postbinding step. In addition, we investigated the structure of A27L protein that provides for its binding to heparan sulfate on cells. A mutant of A27L protein, named D-A27L, devoid of a cluster of 12 amino acids rich in basic residues, was constructed. In contrast to the soluble A27L protein, purified D-A27L protein was inactive in all of our assays, including binding to heparin in vitro, binding to heparan sulfate on cells, and the ability to block virus infection. These data demonstrated that the N-terminal region acts as a glycosaminoglycan (GAG)-binding domain critical for A27L protein binding to cells. Previously A27L protein was thought to be involved in fusion of virus-infected cells induced by acid treatment. When we investigated whether cell surface GAGs also participate in A27L-dependent fusion, our results indicated that soluble A27L protein blocked cell fusion, whereas D-A27L protein did not. Taken together, the results therefore demonstrated that A27L-mediated cell fusion is triggered by its interaction with cell surface GAGs through the N-terminal domain. 相似文献
102.
A novel benzonorbornane-based dietheramine monomer, 3,6-bis(4-aminophenoxy)benzonorbornane (BAPBN), was prepared in two steps from aromatic nucleophilic chloro-displacement reaction of p-chloronitrobenzene with the potassium phenolate of 3,6-dihydroxybenzonorbornane, followed by hydrazine catalytic reduction of the intermediate dinitro compound. A series of benzonorbornane-based polyimides were prepared from the diamine BAPBN with various aromatic dianhydrides via a conventional two-stage synthesis in which the poly(amic acid)s obtained in the first stage were heated stage-by-stage at 150300°C to give the polyimides. The intermediate poly(amic acid)s had inherent viscosities between 0.58 and 2.03 dL/g. Almost all the solution-cast poly(amic acid) films could be thermally converted into flexible and tough polyimide films with good tensile properties. Some polyimides with more flexible backbones exhibited good solubility in polar organic solvents. Depending on the structures of the dianhydrides, the glass-transition temperatures (T
g) of these polyimides were recorded between 209 and 327°C by differential scanning calorimetry (DSC) or dynamic mechanical analysis (DMA), and the softening temperatures (T
s) determined by thermomechanical analysis (TMA) stayed in the 197320°C range. Decomposition temperatures for 10% weight loss all occurred above 480°C in both air and nitrogen atmospheres. The polyimides also showed low dielectric constants (2.62–3.53 at 1 MHz). For the comparative purpose, a series of corresponding polyimides based on l,4-bis(4-aminophenoxy)benzene (BAPB) was also prepared and characterized. 相似文献
103.
Chih-Fan Chen Chi-Huang Hsiao 《Automatic Control, IEEE Transactions on》1975,20(5):596-603
This paper presents a technique for determinating time-varying feedback gains of linear systems with quadratic performance criteria. The gains are approximated by the piecewise constants which axe naturally determined by Walsh functions. After introducing Walsh functions in the beginning we develop an operational matrix for solving state equations. Then using the operational matrix we solve the piecewise constant gains problem. 相似文献
104.
Compared the effects of cholecystokinin (CCK) and bombesin (BBS) on the consummatory response in male albino rats in 3 experiments. The normal licking response pattern did not change as the meal progressed; no predictor was found to indicate when the meal would terminate. Licks normally occurred at about 6/sec, but there were a few licks that occurred at about 3/sec with no licking occurring in the intermediate range; thus, a distinctive bimodal frequency distribution of the interlick interval was formed. CCK reduced the intake of milk and the related licking indices as expected, but it also induced an unusual licking pattern: The contact duration was shortened, the interlick interval was lengthened, and there was an increase in the proportion of licks with long interlick intervals, the effects that accentuated the bimodality of the distribution of interlick intervals. BBS reduced the intake and the related licking indices. The CCK effect may be mediated partially by a change in the motor aspect of the consummatory response; however, BBS reduced intake by simply decreasing the number of licks and shortening the intake duration. BBS may be a candidate for a natural satiety hormone. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
105.
Studies of the mesophase development in polymeric fibers during deformation by synchrotron SAXS/WAXD
Shaofeng Ran Xinhua Zong Dufei Fang Benjamin S. Hsiao Benjamin Chu P. M. Cunniff R. A. Phillips 《Journal of Materials Science》2001,36(13):3071-3077
On-line structural and morphological studies on Kevlar 49 and isotactic polypropylene (iPP) fibers during deformation were carried out using synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). A novel image analysis method was used to extract quantitative fractions of the crystal phase, the amorphous phase and a mesomorphic (intermediate) phase from two-dimensional (2D) WAXD patterns. Results showed that about 20 wt% in the Kevlar 49 fiber had an intermediate mesophase morphology. The transitions between crystal phase, amorphous phase and mesophase were not obvious during deformation of Kevlar 49 fiber at room temperatures. 2D SAXS patterns indicated that the superstructure of the Kevlar 49 fiber was fibril in nature. 2D WAXD results of iPP fibers showed that the -form crystals were quite defective in the initial state and were converted to the well-known mesomorphic form by drawing at room temperatures. The mesophase in Kevlar 49 fibers was then compared with that in iPP fibers. The shape of one-dimensional equatorial peak of the mesophase in the iPP fiber was similar to that in the Kevlar fiber, indicating that the mesophase in both iPP and Kevlar fibers could be similar in some aspects of molecular arrangement. Corresponding 2D SAXS patterns showed that there was no obvious long period in the mesophase of the drawn iPP fiber. We speculate that the constituents of the mesomorphic fraction extracted in the drawn iPP fibers may consist of partially oriented bundles of helical chains with random helical hands as well as oriented chains with no helical structures (consisting of stereo/tacticity defects). The latter is similar to the mesophase of rigid chains in Kevlar fibers, consisting of only oriented chains with no helical structures. 相似文献
106.
Byrne Peter Tangney Brendan Sanchez-Villalon Pedro P. Ortega Manuel Wu Lin-Jung Chang Kao-En Hsiao Hsien-Sheng Sung Yao-Ting 《Distributed Systems Online, IEEE》2007,8(7):3-3
Works in progress from selected papers presented at the 2006 IADIS International Conference on Mobile Learning provide an overview of the diverse research being conducted in this field. 相似文献
107.
Investigation of the Phase Equilibria of Sn-Cu-Au Ternary and Ag-Sn-Cu-Au Quaternary Systems and Interfacial Reactions in Sn-Cu/Au Couples 总被引:1,自引:0,他引:1
Yee-Wen Yen Chien-Chung Jao Hsien-Ming Hsiao Chung-Yung Lin Chiapyng Lee 《Journal of Electronic Materials》2007,36(2):147-158
The phase equilibria of the Sn-Cu-Au ternary, Ag-Sn-Cu-Au quaternary systems and interfacial reactions between Sn-Cu alloys
and Au were experimentally investigated at specific temperatures in this study. The experimental results indicated that there
existed three ternary intermetallic compounds (IMCs) and a complete solid solubility between AuSn and Cu6Sn5 phases in the Sn-Cu-Au ternary system at 200°C. No quaternary IMC was found in the isoplethal section of the Ag-Sn-Cu-Au
quaternary system. Three IMCs, AuSn, AuSn2, and AuSn4, were found in all couples. The same three IMCs and (Au,Cu)Sn/(Cu,Au)6Sn5 phases were found in all Sn-Cu/Au couples. The thickness of these reaction layers increased with increasing temperature and
time. The mechanism of IMC growth can be described by using the parabolic law. In addition, when the reaction time was extended
and the Cu content of the alloy was increased, the AuSn4 phase disappeared gradually. The (Au, Cu)Sn and (Cu,Au)6Sn5 layers played roles as diffusion barriers against Sn in Sn-Cu/Au reaction couple systems. 相似文献
108.
In many RFID applications, the reader repeatedly identifies the same staying tags. Existing anti-collision protocols can rapidly identify the staying tags by remembering the order in which the tags were recognized in the previous identification process. This paper proposes a novel protocol, dynamic blocking adaptive binary splitting (DBA), based on the blocking mechanism, which prevents the newly-arriving tags from colliding with the staying tags. Moreover, DBA utilizes a dynamic condensation technique to reduce the number of idle slots produced when recognized tags leave. Following the condensation process, multiple staying tags may be required to share the same slot, and thus may cause collisions among them. Accordingly, an efficient ordering binary tree mechanism is proposed to split the collided tags deterministically according to the order in which they were recognized. The analytical and simulation results show that DBA consistently outperforms previous algorithms in all of the considered environments. 相似文献
109.
110.
In the early stage of a design process, it is important to create numerous and varied possible color plans for the target consumer group. These color plans help individual designers quickly find a few good color design schemes and give the design team ideas for brainstorming. The color plan of a product consists of the color combinations of its components and decorative patterns, which strongly influence the feelings of customers and thus their desire to purchase. However, very few studies have discussed these issues. In this study, a consultation and simulation system for product color planning that helps designers obtain the optimal color planning for components and decorative patterns of a product is proposed. This system includes two parts: one uses the interactive genetic algorithm to establish a creative evolutionary system that can interact with a designer to explore novel design schemes; the other extends the boundary extract algorithm to establish a color simulation system that can apply colors to the areas of product components and decorative patterns for color simulation. Finally, a case study of color planning for a motorcycle model is used to verify the feasibility of the proposed system. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 375–390, 2013 相似文献