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21.
Tetsuya Tanigami Kanna Kai Koji Tanaka Shuji Matsuzawa 《Journal of Inorganic and Organometallic Polymers》2003,13(4):237-253
Poly[bis(-phenoxyethoxy)phosphazene] [PBPEP] had been shown in our previous paper to be a very useful polymer for investigating the crystallization mechanism of polymers, as the crystallization rate of PBPEP is extraordinarily small when isothermally crystallized from the melt. The crystallization of the low molecular weight oligomers of PBPEP was first studied in comparison to the high molecular weight polymers. The oligomer-rich fraction was obtained by fractionation of the as-polymerized sample, which had a broad molecular weight distribution. The fractions thus obtained were characterized by solution viscometry and size exclusion chromatography. The melting temperature and the growth rate of the spherulite from the melt were investigated by differential scanning calorimetry and optical microscopy. The growth rate was one or two orders of magnitude smaller in the oligomer-rich fraction than in the other high molecular weight fractions. A collapsed spherulite appeared in the oligomer-rich fraction at high crystallization temperatures. It is speculated that in the oligomer-rich fraction there is an excess free energy due to defects in the crystal phase. This defect is considerably larger in the oligomer-rich fraction than in the other fractions because a large quantity of short length chains is present. 相似文献
22.
Kojima Shuichi; Takagi Nobuyuki; Minagawa Tetsuya; Fushimi Noriko; Miura Kin-ichiro 《Protein engineering, design & selection : PEDS》1999,12(10):857-862
We have previously shown that replacing the P1-site residue(Ala) of chicken ovomucoid domain 3 (OMCHI3) with a Met or Lysresults in the acquisition of inhibitory activity toward chymotrypsinor trypsin, respectively. However, the inhibitory activitiesthus induced are not strong. In the present study, we introducedadditional amino acid replacements around the reactive siteto try to make the P1-site mutants more effective inhibitorsof chymotrypsin or trypsin. The amino acid replacement AspTyrat the P2' site of OMCHI3(P1Met) resulted in conversion to a35000-fold more effective inhibitor of chymotrypsin with aninhibitor constant (Ki) of 1.17x1011 M. The Ki valueof OMCHI3(P1Met, P2'Ala) indicated that the effect on the interactionwith chymotrypsin of removing a negative charge from the P2'site was greater than that of introducing an aromatic ring.Similarly, enhanced inhibition of trypsin was observed whenthe AspTyr replacement was introduced into the P2' site of OMCHI3(P1Lys).Two additional replacements, AspAla at the P4 site and ArgAlaat the P3' site, made the mutant a more effective inhibitorof trypsin with a Ki value of 1.44x109 M. By contrast,ArgAla replacement at the P3' site of OMCHI3(P1Met, P2'Tyr)resulted in a greatly reduced inhibition of chymotrypsin, andAspAla replacement at the P4 site produced only a small changewhen compared with a natural variant of OMCHI3. These resultsclearly indicate that not only the P1-site residue but alsothe characteristics, particularly the electrostatic properties,of the amino acid residues around the reactive site of the proteaseinhibitor determine the strength of its interactions with proteases.Furthermore, amino acids with different characteristics arerequired around the reactive site for strong inhibition of chymotrypsinand trypsin. 相似文献
23.
This study concerns a comparative study of three crosslinkers, divinylbenzene (DVB), 1,2‐bis(p,p‐vinylphenyl)ethane (BVPE), and triallyl cyanurate (TAC) crosslinked poly(ethylene‐co‐tetrafluoroethylene) (ETFE)‐based radiation‐grafted membranes, which were prepared by radiation grafting of p‐methylstyrene onto ETFE films and subsequent sulfonation. The effect of the different types and contents of the crosslinkers on the grafting and sulfonation, and the properties such as water uptake, proton conductivity, and thermal/chemical stability of the resulting polymer electrolyte membranes were investigated in detail. Introducing crosslink structure into the radiation‐grafted membranes leads to a decrease in proton conductivity due to the decrease in water uptake. The thermal stability of the crosslinked radiation‐grafted membranes is also somewhat lower than that of the noncrosslinked one. However, the crosslinked radiation‐grafted membranes show significantly higher chemical stability characterized in the 3% H2O2 at 50°C. Among the three crosslinkers, the DVB shows a most pronounced efficiency on the crosslinking of the radiation‐grafted membranes, while the TAC has no significant influence; the BVPE is a mild and effective crosslinker, showing the moderate influence between the DVB and TAC crosslinkers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4565–4574, 2006 相似文献
24.
Satoshi Ueki Tetsuya Mouri Takahiro Endo Haruhisa Kawasaki 《Artificial Life and Robotics》2016,21(1):31-36
This paper proposes a method for visualizing the stiffness of a soft object in a palpation-support information system by the teleoperation of a robot hand. It is important that a palpation system display a body’s shape and stiffness. In our method, the stiffness of the contact area between the soft object and the robot finger is estimated by a recursive least-squares method with forgetting factor that uses an impedance dynamics model. With the estimated stiffness and direction of contact force, we calculate the scalar parameter for visualization of stiffness. Moreover, we propose a safety control method for the palpation system, which is part of a tele-control method based on will-consensus building. The system configuration, estimated algorithm, and experimental results are presented. 相似文献
25.
Tetsuya Takahashi Yoshinori Dobashi Issei Fujishiro Tomoyuki Nishita Ming C. Lin 《Computer Graphics Forum》2015,34(2):493-502
We propose a stable and efficient particle‐based method for simulating highly viscous fluids that can generate coiling and buckling phenomena and handle variable viscosity. In contrast to previous methods that use explicit integration, our method uses an implicit formulation to improve the robustness of viscosity integration, therefore enabling use of larger time steps and higher viscosities. We use Smoothed Particle Hydrodynamics to solve the full form of viscosity, constructing a sparse linear system with a symmetric positive definite matrix, while exploiting the variational principle that automatically enforces the boundary condition on free surfaces. We also propose a new method for extracting coefficients of the matrix contributed by second‐ring neighbor particles to efficiently solve the linear system using a conjugate gradient solver. Several examples demonstrate the robustness and efficiency of our implicit formulation over previous methods and illustrate the versatility of our method. 相似文献
26.
Akihiro Nagase Eiji Niikura Masaru Shinozaki Tetsuya Nagayasu Taiji Kondo Gosuke Ohashi 《Journal of the Society for Information Display》2013,21(7):295-304
The color gamut is one of the critical parameters that dictate the image quality of displays. The liquid crystal displays using white color light‐emitting diodes (LEDs) as the backlight, though having been widely employed recently, are not very satisfactory in terms of their color gamut because of the broad spectrum inherent to white LEDs. This prompted the authors to develop improved liquid crystal displays using an edge‐lit wide color gamut backlight that used red laser diodes and cyan LEDs. Generating laser beams with high color purity, the laser diodes are light sources with a significant effect on expanding the color gamut. However, laser diodes, red ones in particular, have unfavorable thermal characteristics. To cope with this shortcoming, the authors clearly defined the restrictive criteria for laying out two kinds of light source on the edge‐lit backlight and made a prototype 55‐type laser backlight for performance evaluation. 相似文献
27.
Ryoichi Kawahara Tetsuya Takine Tatsuya Mori Noriaki Kamiyama Keisuke Ishibashi 《Computer Networks》2013,57(6):1560-1576
We consider the mean–variance relationship of the number of flows in traffic aggregation, where flows are divided into several groups randomly, based on a predefined flow aggregation index, such as source IP address. We first derive a quadratic relationship between the mean and the variance of the number of flows belonging to a randomly chosen traffic aggregation group. Note here that the result is applicable to sampled flows obtained through packet sampling. We then show that our analytically derived mean–variance relationship fits well those in actual packet trace data sets. Next, we present two applications of the mean–variance relationship to traffic management. One is an application to detecting network anomalies through monitoring a time series of traffic. Using the mean–variance relationship, we determine the traffic aggregation level in traffic monitoring so that it meets two predefined requirements on false positive and false negative ratios simultaneously. The other is an application to load balancing among network equipments that require per-flow management. We utilize the mean–variance relationship for estimating the processing capability required in each network equipment. 相似文献
28.
In this paper, we provide an overview of challenges in mobile search and ranking, and envision the fundamental features that
should be satisfied. We argue that two principles will help improve the relevance and quality of mobile search and ranking:
the first one is to examine both intrinsic content features and context of items (usage statistics and social features, etc.);
and the second one lies in that no algorithms can replace the objectivity of a human being—let users define the sites that
they feel are relevant, leverage their social networks, and over time see their results become highly personalized. Specifically,
wireless-virtualcommunity-based mobile search and ranking architecture is proposed in this paper, in which communities act
as a first class abstraction for information sharing. Then, we introduce briefly the potential procedures of achieving high
relevance and quality in mobile search and ranking based on wireless virtual community. 相似文献
29.
M. Nakao Y. Hatamura T. Sato K. Koyano K. Ichiki H. Sangu M. Hatakeyama T. Kobata K. Nagai 《Microsystem Technologies》1995,1(3):124-128
In order to make micro 3-D structures, we are designing a table-sized factory, namely Nano Manufacturing World (NMW). In NMW, we challenged to use a new process fused by semiconductor process for preciseness and machine process for 3-dimensionality. In order to realize the new process, we designed three new mechanisms in this paper: multi-face shape making beam, co-focus rotational robot and micro mechanical tools. Through an evaluation to actually make a micro Gojunoto with the mechanisms, we confirmed their validities for functions of integration of 3-D shape construction and assembly. 相似文献
30.
Particulate TiC-reinforced aluminum composite specimens were processed by compacting a mixture of titanium, carbon, and aluminum
powders into preforms that were infiltrated with molten aluminum and subsequently heated in a differential thermal analyzer
to about 1573 K under argon atmosphere. The onset of formation of TiC particles began at about 1150 K by reaction of TiAl3 with Al4C3. Subsequent formation of TiC particles at higher temperatures to approx-imately 1265 K occurred by direct reaction of carbon
with TiAl3. Above this temperature, the TiC particles coarsened with increasing temperature from an initial size of about 0.15μm. TiC
particles were also produced in preforms that were not infiltrated; however, the presence of liquid aluminum in infiltrated
specimens inhibited particle agglomeration and sintering. Infil-trated preforms could, therefore, serve as excellent "master
alloys" for subsequent dilution in an aluminum melt and processing of metal-matrix composites (MMCs) reinforced with sub-micron
TiC particulates.
Formerly Research Scientist, Massachusetts Institute of Technology, Cambridge, MA 02139 相似文献