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31.
Transdermal Iontophoretic Delivery of Thyrotropin-Releasing Hormone Across Excised Rabbit Pinna Skin
Enhanced transport of a model peptide drug thyrotropin-releasing hormone (TRH), a tripeptide of molar mass 362 g and a pKa 6.2, through excised rabbit pinna skin was achieved by means of iontophoresis with continuous current or monophase periodically pulsed current. The resulting flux in the steady state was proportional to the applied current density. In the transdermal iontophoretic delivery of TRH, the pulsed iontophoretic flux exceeded that obtained with a continuous current. At a low ionic strength, an increased degree of protonation in TRH increased the rate of permeation. The flux of TRH in a buffer at pH 4 is greater than that at pH 8 when the ionic strength is 0.1 M. At a greater ionic strength, the trend is reversed. The enhanced flux of unprotonated TRH during transdermal iontophoresis is attributed largely to electro-osmotic volume flow. An increased rate of permeation of TRH crossing the skin is achieved at low ionic strength, moderate pH, and a large duly cycle of current; the frequency of pulsed current had no significant influence on the rate of transdermal iontophoretic delivery of TRH. 相似文献
32.
W. W. Gerberich H. Huang W. Zielinski P. G. Marsh 《Metallurgical and Materials Transactions A》1993,24(3):535-543
An interconnected set of observations assesses current equilibrium models of the ductile-brittle-transition temperature (DBTT).
This involvesin situ transmission electron microscopy (TEM) studies of crack-tip dislocations in single and polycrystals and bulk fracture toughness
tests at various temperatures. Beyond KI values of 8 MPa · m1/2 in both iron-base single and polycrystals, large numbers of redundant dislocations are created, as postulated recently by
Weertman. [38] Still, the necessary shielding dislocations, as required by equilibrium, can be detected at values as high
as 20 and 40 MPa · m1/2 byex situ TEM and electron channeling, respectively. In addition, the close approach of dislocations to the crack tip in some of the
studies, as opposed to others, suggests that large dislocation free zones (DFZ) are a thin-film artifact. However, a failure
criterion based partly on the Rice-Thomson model’21 is both consistent with the absence of a large DFZ and observed fracture
toughness variations with test temperature. It is emphasized that this toughness transition is entirely in the semibrittle
regime where cleavage is the failure mode. Nevertheless,K
lc values increase from 3 to 60 MPa·m1/2 with an increase in test temperature.
This article is based on a presentation made in the symposium “Quasi-Brittle Fracture” presented during the TMS fall meeting,
Cincinnati, OH, October 21–24, 1991, under the auspices of the TMS Mechanical Metallurgy Committee and the ASM/MSD Flow and
Fracture Committee. 相似文献
33.
34.
钛容器的特点 总被引:2,自引:1,他引:1
黄嘉琥 《石油化工设备技术》1996,17(5):19-24
根据钛材的化学、物理、力学和工艺性能介绍了钛容器在设计、制造、检验和应用方面的特点。 相似文献
35.
36.
RG Wilde JT Billheimer SJ Germain EA Hausner PC Meunier DA Munzer JK Stoltenborg PJ Gillies DL Burcham SM Huang JD Klaczkiewicz SS Ko RR Wexler 《Canadian Metallurgical Quarterly》1996,4(9):1493-1513
Acyl-CoA:cholesterol acyltransferase (ACAT) is the enzyme largely responsible for intracellular cholesterol esterification. A systemic inhibitor of ACAT is believed to be able to slow or even reverse the atherosclerotic process. Towards that goal, a series of cyclic sulfides, derived from the hetero-Diels-Alder reaction of thioaldehydes with 1,3-dienes, and bearing carboxamide substituents, were prepared and evaluated for in vitro (in several tissues and species) and ex vivo ACAT inhibition. Minor changes in subsequent structure were found to have a significant effect in optimization of the biological activity of this series of compounds. 相似文献
37.
Shyh-Jier Huang Jeu-Min Lin 《Power Systems, IEEE Transactions on》2002,17(4):1022-1029
In this paper, a gap-statistic-algorithm (GSA)-based data-mining technique is applied to enhance the data debugging in power system operations. In the proposed approach, the GSA technique is embedded into a neural network frame in anticipation of improving the detection capability of bad data. Thanks to the clustering capability exhibited by GSA in which the number of clusters can be optimally determined, the proposed approach becomes highly effective to localize the group of abnormal data. This proposed approach has been tested through the data collected from different scenarios made on an IEEE 30-bus system and 118-bus systems. Test results reveal the feasibility of the method for the data diagnosis applications. 相似文献
38.
Tzu-Ming Liu Yin-Chieh Huang Gia-Wei Chern Kung-Hsuan Lin Yu-Chueh Hung Chih-Jie Lee Chi-Kuang Sun 《Quantum Electronics, IEEE Journal of》2002,38(11):1529-1535
We present a method to obtain complete information of femtosecond pulses. By measuring triple-optical autocorrelation directly with third-harmonic generation, without spectral information, a temporal pulse shape can be obtained by analytical calculation without direction-of-time ambiguity. Combining the resulting optical pulse shape with its corresponding optical spectrum, the exact phase and color variations in time can all be recovered with a Gerchberg-Saxton algorithm through an iterative calculation with an O(n) complexity. 相似文献
39.
An orthogonal basis for the hyperbolic hybrid polynomial space 总被引:1,自引:0,他引:1
Motivated by the wide usage of the Tchebyshev basis and Legendre basis in the algebra polynomial space, we construct an orthogonal basis with the properties of the H-Bézier basis in the hyperbolic hybrid polynomial space, which is similar to the Legendre basis and holds remarkable properties. Moreover, we derive the transformation matrices that map the H-Bézier basis and the orthogonal basis forms into each other. An example for approximating the degree reduction of the H- Bézier curves is sketched to illustrate the utility of the orthogonal basis. 相似文献
40.