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21.
Terry Carolyn J.; Blake Colin C. F. 《Protein engineering, design & selection : PEDS》1992,5(6):505-510
The structure of cleaved thyroxine-binding globulin (TBG) hasbeen modelled on the crystal structure of cleaved 1-antitrypsin(a member of the serine proteinase inhibitor, serpin, superfamily)based on the high sequence homology exhibited by the two proteins.Particular attention was paid to the identification and modelledcharacteristics of the thyroxine binding site. The primary aimof the study was to compare the site qualitatively with thecrystallographically determined binding site of transthyretin,the other major transporter of thyroxine, in an attempt to explainthe higher binding affinity of the site compared with the knownthyrox ine binding site in transthyretin (1010 versus 108 M1).The proposed binding site shares some similar characteristicswith the transthyretin binding site but also includes a clusterof aromatic residues which are entirely absent in transthyretin.It is proposed that this might account for the substantial differencein binding affinities. 相似文献
22.
Carlos G. Levi Eric Sommer Scott G. Terry Amalia Catanoiu Manfred Rühle 《Journal of the American Ceramic Society》2003,86(4):676-85
The microstructure of Al2 O3 formed by oxidation of a model NiCrAlY alloy during electron-beam physical vapor deposition of ZrO2 –7.6 mol% YO1.5 is examined and compared with that formed on the bare substrate. The growth rate, morphology, and chemical composition of the oxide vary among the different constituents of the alloy surface and are further influenced by the O2 partial pressure and the physical presence of the thermal barrier coating (TBC) layer. These differences, however, are largely limited to the outer oxide layer. The interplay between the TBC and the growing oxide leads to the formation of a fine-grain Al2 O3 –ZrO2 "mixed zone" within the thermally grown oxide. A mechanism is outlined to explain this behavior, based on the dissolution of ZrO2 in a transient Al2 O3 structure growing by outward diffusion of Al, and its subsequent reprecipitation when the metastable phase transforms to the stable α-Al2 O3 form. 相似文献
23.
Meadowfoam fatty acids, when treated with mineral acid catalysts in the presence of polar nonparticipating solvents, undergo
a facile ring closure to form δ-lactones. Perchloric and sulfuric acids catalyze the cyclization at concentrations of 0.6–13
mole equivalents, both neat and in the presence of solvent. Under constant acid concentrations, methylene chloride was found
to increase the rate of reaction, the regioselectivity for the formation of δ-lactone, and the overall yield. In the absence
of solvent, increased acid concentration improved the yield of lactone but reduced regioselectivity for the δ-isomer. Solvent
polarity plays a significant role in the regioselectivity of the cyclization for δ-lactone, with solvents of higher dielectric
strength providing larger δ/γ ratios (38:1) and higher yields up to 92%. 相似文献
24.
Keiichiro Oh-ishi John Boydon Terry R. McNelley 《Journal of Materials Engineering and Performance》2004,13(6):710-719
The importance of grain size refinement in enabling superplasticity is reviewed, and the current understanding of grain boundary
characteristics is summarized. The application of orientation-imaging microscopy (OIM) methods to the processing response
and the deformation and failure modes in superplastic aluminum alloys are illustrated through microtexture analysis and determination
of grain boundary characteristics in selected commercial materials. Continuous and discontinuous recrystallization reactions
exhibit distinct microtextures and grain boundary characteristics. The application of OIM and microtexture analysis to the
evaluation of both deformation and failure mechanisms during superplastic forming is illustrated.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
25.
Terry C. Lowe Ruslan Z. Valiev 《JOM Journal of the Minerals, Metals and Materials Society》2004,56(10):64-68
Severe plastic deformation (SPD) has emerged as a promising method to produce ultrafine-grained materials with attractive
properties. Today, SPD techniques are rapidly developing and are on the verge of moving from lab-scale research into commercial
production. This paper discusses new trends in the development of SPD techniques suchas high-pressure torsion and equal-channel
angle pressing, as well as new alternative techniques for introducing SPD. The paper also contains a comparative analysis
of SPD techniques in terms of their relative capabilities for grain refinement, enhancement of properties, and potential to
economically produce ultrafine-grained metals and alloys.
For more information, contact Terry C. Lowe, Science and Technology Base Programs, Los Alamos National Laboratory, Los Alamos,
NM 87545; (505) 667-7824; fax (505) 665-3199; e-mail tlowe@lanl.gov. 相似文献
26.
Testing Forecast Accuracy of Foreign Exchange Rates: Predictions from Feed Forward and Various Recurrent Neural Network Architectures 总被引:3,自引:1,他引:2
In this research, we work with data of futures contracts on foreign exchange rates for British pound (BP), Canadian dollar
(CD), and Japanese yen (JY) that are traded at the Chicago Mercantile Exchange (CME) against US dollars. We model relationships
between exchange rates in these currencies using linear models, feed forward artificial neural networks (ANN), and three versions
of recurrent neural networks (RNN1, RNN2 and RNN3) for predicting exchange rates in these currencies against the US dollar.
Our results on forecast evaluations based on AGS test the tests of forecast equivalence between any two competing models among
the entire models employed for each of the series show that ANN and the three versions of RNN models offer superior forecasts
for predicting BP, CD and JY exchange rates although the forecast evaluations based on MGN test are in sharp contrast. On
the other hand forecast based on SIGN test shows that ANN and all the versions of RNN models offer superior forecasts for
BP and CD in exception of JY exchange rates. The results for forecast evaluation for all the models for each of the series
based on summary measures of forecast evaluations show that RNN3 model appears to offer the most accurate predictions of BP
and RNN1 for JP exchange rates. However, none of the RNN models appear to be statistically superior to the benchmark (i.e.,
linear model) for predicting CD exchange rates.
相似文献
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29.
Cigarette smoking and the colorectal adenoma-carcinoma sequence: a hypothesis to explain the paradox
As recognized precursor lesions to colorectal cancer, colorectal adenomatous polyps have been studied to enhance knowledge of colorectal cancer etiology. Although most of the known risk factors for colorectal cancer are also associated with the occurrence of colorectal adenomas, cigarette smoking has had a strong, consistent relationship with colorectal adenomas but is generally not associated with colorectal cancer. The explanation for this paradox is unknown. With data collected in 1986-1988 during a large case-control study based on colonoscopy results in New York City, New York, the authors investigated the possibility that the paradox may arise because subjects with colorectal adenomas were included in the control group of cancer case-control studies. The authors found a statistically significant increased risk between heavy cigarette smoking (smokers with > or = 40 pack-years of smoking) and risk of adenoma (odds ratio (OR) = 1.61, 95% confidence interval (CI) 1.06-2.44). They saw no increased colorectal cancer risk from heavy cigarette smoking (OR = 1.02, 95% CI 0.52-1.99) using a "manufactured" control group to simulate a typical unscreened, population-based control group. When the authors compared these colorectal cancer cases with an adenoma-free control group examined by colonoscopy in a polytomous model with several case groups (newly diagnosed adenomas, carcinoma in situ, intramucosal carcinoma, and colorectal cancer), they found that the risk for 20-39 pack-years of smoking was elevated, although not statistically significant, and was similar for all four case groups. The risk for the highest smoking category (> or = 40 pack-years) was more strongly elevated in all four case groups, although it was statistically significant for only the newly diagnosed adenoma and the carcinoma in situ cases (adenomas, OR = 1.59, 95% CI 1.05-2.42; carcinoma in situ, OR = 2.05, 95% CI 1.01-4.15; intramucosal carcinoma, OR = 1.30, 95% CI 0.61-2.77; and colorectal cancer, OR = 1.30, 95% CI 0.64-2.65). While the authors' study is weakened by the lack of statistical significance concerning risk for colorectal cancer, these data offer some support for the hypothesis that the association between cigarette smoking and risk of colorectal cancer may have been masked by inclusion in the control group of subjects with adenomas. They also suggest that the major effect of smoking on the colorectal adenoma-carcinoma sequence occurs in the earlier stages of the formation of adenoma and the development of carcinoma in situ. 相似文献
30.
Robert Withnall Jack Silver Paul G. Harris Terry G. Ireland Paul J. Marsh 《Journal of the Society for Information Display》2011,19(11):798-810
Abstract— The current status of AC powder electroluminescent (ACPEL) displays is reviewed with particular emphasis given to color and lifetime. The printing of the displays in forward and reverse architectures is also discussed, in addition to the fabrication of ACPEL displays with interdigitated electrodes, and different types of ACPEL phosphors and materials for back electrodes, transparent conducting electrodes, binders, and dielectrics are considered. Furthermore, shape conformable and highly flexible ACPEL displays are surveyed. 相似文献