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111.
Chengkuo Lee Itoh T. Suga T. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1996,43(4):553-559
A micromachined lead zirconate titanate (PZT) force sensor for scanning force microscope (SFM) is conceptualized by its piezoelectricity. The fabrication procedure is interpreted, and mechanical characteristics of the micromachined PZT force sensors with various lengths are studied in this paper. A compact SFM is constructed by using the piezoelectric PZT sensor. A very clear image is taken by this SFM. The current study of the micromachined PZT force sensor can be considered as a breakthrough of design of SFM as well as a good example of integrated piezoelectric microdevices 相似文献
112.
113.
The AA7075 alloys reinforced with SiC and without SiC particles were fabricated by a pressureless infiltration method, and
then, their tensile properties and microstructures were analyzed. The spontaneous infiltration of molten metal at 800 °C for
1 hour under a nitrogen atmosphere made it possible to fabricate 7075 Al matrix composite reinforced with SiC, as well as
a control 7075 Al without SiC. A significant strengthening even in the control alloy occurred due to the formation of in-situ AlN particle even without an addition of SiC particles. Composite reinforced with SiC particles exhibited higher strength
values than the control alloy in all aging conditions (underaged (UA), peak-aged (PA), and overaged (OA)), as well as a solution
treated condition. Spontaneous infiltration was further prompted owing to the combined effect of both Mg and Zn. This may
lead to an enhancement of wetting between the molten alloy and the reinforcement. Consequently, strength improvement in a
composite may be attributed to good bond strength via enhancement of wetting. The grain size of the control alloy is greatly decreased to about 2.5 μm compared to 10 μm for the
commercial alloy. In addition, the grain size in the composite is further decreased to about 2 μm. These grain refinements
contributed to strengthening of the control alloy and the composite. 相似文献
114.
Measuring knowledge transfer between fields of science 总被引:4,自引:2,他引:2
Rinia Ed J. van Leeuwen Thed N. Bruins Eppo E. W. van Vuren Hendrik G. van Raan Anthony F. J. 《Scientometrics》2002,54(3):347-362
In this paper we report on the results of an exploratory study of knowledge exchange between disciplines and subfields of
science, based on bibliometric methods. The goal of this analysis is twofold. Firstly, we consider knowledge exchange between
disciplines at a global level, by analysing cross-disciplinary citations in journal articles, based on the world publication
output in 1999. Among others a central position of the Basic Life Sciences within the Life Sciences and of Physics within
the Exact Sciences is shown. Limitations of analyses of interdisciplinary impact at the journal level are discussed. A second
topic is a discussion of measures which may be used to quantify the rate of knowledge transfer between fields and the importance
of work in a given field or for other disciplines. Two measures are applied, which appear to be proper indicators of impact
of research on other fields. These indicators of interdisciplinary impact may be applied at other institutional levels as
well.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
115.
Michael Anthony Puso Tod A. Laursen 《International journal for numerical methods in engineering》2002,54(8):1161-1194
In this work, a method is developed for smoothing three‐dimensional contact surfaces. The method can be applied to both regular and irregular meshes. The algorithm employs Gregory patches to interpolate finite element nodes and provide tangent plane continuity between adjacent patches. The resulting surface interpolation is used to calculate gaps and contact forces, in a variationally consistent way, such that contact forces due to normal and frictional contact vary smoothly as slave nodes transition from one patch to the next. This eliminates the ‘chatter’ which typically occurs in a standard contact algorithm when a slave node is situated near a master facet edge. The elimination of this chatter provides a significant improvement in convergence behaviour, which is illustrated by a number of numerical examples. Furthermore, smoothed surfaces also provide a more accurate representation of the actual surface, such that resulting stresses and forces can be more accurately computed with coarse meshes in many problems. This fact is also demonstrated by the numerical examples. Published in 2002 by John Wiley & Sons, Ltd. 相似文献
116.
117.
BH Shieh MY Zhu JK Lee IM Kelly F Bahiraei 《Canadian Metallurgical Quarterly》1997,94(23):12682-12687
Visual transduction in Drosophila is a G protein-coupled phospholipase C-mediated process that leads to depolarization via activation of the transient receptor potential (TRP) calcium channel. Inactivation-no-afterpotential D (INAD) is an adaptor protein containing PDZ domains known to interact with TRP. Immunoprecipitation studies indicate that INAD also binds to eye-specific protein kinase C and the phospholipase C, no-receptor-potential A (NORPA). By overlay assay and site-directed mutagenesis we have defined the essential elements of the NORPA-INAD association and identified three critical residues in the C-terminal tail of NORPA that are required for the interaction. These residues, Phe-Cys-Ala, constitute a novel binding motif distinct from the sequences recognized by the PDZ domain in INAD. To evaluate the functional significance of the INAD-NORPA association in vivo, we generated transgenic flies expressing a modified NORPA, NORPAC1094S, that lacks the INAD interaction. The transgenic animals display a unique electroretinogram phenotype characterized by slow activation and prolonged deactivation. Double mutant analysis suggests a possible inaccessibility of eye-specific protein kinase C to NORPAC1094S, undermining the observed defective deactivation, and that delayed activation may similarly result from NORPAC1094S being unable to localize in close proximity to the TRP channel. We conclude that INAD acts as a scaffold protein that facilitates NORPA-TRP interactions required for gating of the TRP channel in photoreceptor cells. 相似文献
118.
Synthesis of poly(gamma-glutamate) metabolites of natural folates and antifolates is a critical process. Folypolyglutamates are essential for cell proliferation. Polyglutamates of glutamate (Glu)-containing antifolates are often critical for their cytotoxic action and are relevant to antifolate resistance. However, the role of polyglutamate synthesis in selectivity is less clear. We have undertaken a research program to further define the significance of polyglutamate metabolism and to devise ways to exploit this metabolism to achieve greater therapeutic selectivity in cancer chemotherapy. This article briefly reviews several approaches tested thus far. Inhibition of folypolyglutamate synthesis should lead to cell death. Current ornithine (Orn)-containing folate-based inhibitors of the enzyme responsible for their synthesis, folypolyglutamate synthetase (FPGS), are poorly transported, apparently because of interference by the protonated delta-amine. Replacement of Orn with 4, 4-difluoroOrn, the delta-amine of which has a much lower pKa and is thus less protonated at physiological pH, was explored. Since it is unclear how polyglutamylation contributes to selectivity, we explored generic means either to eliminate or to enhance polyglutamylation. The data indicate that substitution for Glu in an antifolate by some Glu analogs in which the gamma-COOH is either altered or replaced (e.g., gamma-tetrazole-Glu) leads to loss of both FPGS substrate activity and binding; antifolate target specificity is unchanged, while uptake is actually enhanced. Substitution of 3,3-difluoroGlu for Glu leads to enhanced polyglutamylation (although probably only to the diglutamate), retention of target specificity, and at least equal uptake. Comparative studies of the same antifolate containing different replacements for Glu, such as gamma-tetrazole-Glu (no polyglutamylation) or 3,3-difluoroGlu (enhanced polyglutamylation), will be useful in exploring the role and significance of polyglutamylation. 相似文献
119.
Consistent calculation of fugacities of fluid mixtures remains as one of the most important subjects in contemporary molecular
thermodynamics. In practice, equations of state (EOSs) and gE-models have been used. However, most EOSs are erroneous for condensed phases at high densities and gE-models are inapplicable for pressuresensitive systems. Recently to remedy the shortcomings in both approaches, there has
been a surge of new gE-EOS mixing rules. By equating any set of EOS and gE-models, the limitations in both approaches could be resolved significantly. However, the self-consistency in the underlying
concept of those mixing rules remains controversial. During the last several years, the present authors proposed a new lattice-fluid
EOS and its simplification relevant to phase equilibrium calculations. Without employing any gE-EOS mixing rule and with only two parameters for a pure component and one adjustable interaction energy parameter for a binary
mixture, results obtained to date demonstrated that the EOSs are quantitatively applicable to a great variety of phase equilibrium
properties of mixtures, especially, for complex and/or macromolecular systems. In the present article we summarize the EOSs
and extended the applications to liquid-liquid Equilibria. In part I, we discussed briefly the molecular thermodynamic aspects
of general derivation of the EOS and a brief discussion of applying the EOSs to pure fluids while the illustrative application
to various real mixture systems is discussed in part II. 相似文献
120.
Young-Wan Choi O-Kyun Kwon El-Hang Lee 《Photonics Technology Letters, IEEE》1993,5(12):1406-1409
The authors report significantly improved performances of a symmetric self-electrooptic-effect device (S-SEED), with high on-off contrast ratio (>30:l) and large optical bistability loop widths (ΔP=44%) at an applied bias of Va=0 V, i.e., with no power supply. The S-SEED is made of extremely shallow quantum wells (ESQWs) in an asymmetric Fabry-Perot (AFP) cavity structure. At Va =5 V ΔP increased by up to 95%, preserving the high contrast ratio. The reflectivity changes at Va=0 and 5 V were about 15% and 30%, respectively. These are believed to be the largest values ever reported for such structures 相似文献