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61.
Summary The present paper reports the first evidence that homocarnosine-carnosine synthetase from rat brain requires free sulfhydryl groups for activity. The activity of the synthetase can be stabilized by dithioerythritol and inhibited strongly by Cu2+, Cd2+, Hg2+, Zn2+, and to a lesser extent by Ca2+, Ni2+, Li, chlorpromazine, -methyl DOPA and norepinephrine at the concentrations tested.Acknowledgment. This work was supported by United States Public Health Service Grant No. NS-06137. 相似文献
62.
A view of manufacturing processes is presented in which five distinct categories are defined as casting, deformation, machining, joining, and solid freeforming. Solid freeforming is essentially biomimetic and shares problems of morphogenesis with natural processes. Our team in University of London has been exploring three mechanisms of solid freeforming. In dry powder deposition and direct ink-jet printing, the emphasis has turned to the problem of delivering a complex shape in which the three dimensional spatial arrangement of composition is delivered from the design file. In extrusion freeforming, the aim is to control microstructure at hierarchical levels also from the design file. The quest for 3-D functional gradients is satisfied by acoustic and ultrasonic dispensing and mixing of powders so that each layer can be patterned. These methods could be extended to deliver the complex patterns demanded by left-handed microwave metamaterials. Dry powder deposition and direct ink-jet printing are turning towards combinatorial methods in which multiple sample libraries are used to accelerate discovery. In turn, this paves the way for ‘autonomous research machines’ which steer their own search refinements in response to our requests for new materials. In this way, solid freeforming used for sample preparation can give an ‘arm’ to an intelligent machine so that it can conduct its own experimentation and learning; an idea that originated with Alan Turing in the late 1940s. 相似文献
63.
A view of manufacturing processes is presented in which five distinct categories are defined as casting, deformation, machining, joining, and solid freeforming. Solid freeforming is essentially biomimetic and shares problems of morphogenesis with natural processes. Our team in University of London has been exploring three mechanisms of solid freeforming. In dry powder deposition and direct ink-jet printing, the emphasis has turned to the problem of delivering a complex shape in which the three dimensional spatial arrangement of composition is delivered from the design file. In extrusion freeforming, the aim is to control microstructure at hierarchical levels also from the design file. The quest for 3-D functional gradients is satisfied by acoustic and ultrasonic dispensing and mixing of powders so that each layer can be patterned. These methods could be extended to deliver the complex patterns demanded by left-handed microwave metamaterials. Dry powder deposition and direct ink-jet printing are turning towards combinatorial methods in which multiple sample libraries are used to accelerate discovery. In turn, this paves the way for ’autonomous research machines’ which steer their own search refinements in response to our requests for new materials. In this way, solid freeforming used for sample preparation can give an ’arm’ to an intelligent machine so that it can conduct its own experimentation and learning; an idea that originated with Alan Turing in the late 1940s. 相似文献
64.
It is easy to apply lines in design drawings to create different styles, however, there is no guarantee that all the style lines drawn are able to be manufactured. In this paper, we focus on one undeliverable style to enhance our understanding of the relationship between the design sketch and the pattern design process. In order to evidence that such style is unworkable, a systematic display of pattern development, and to be reinforced by mathematical evaluation, will be introduced and addressed. When one can easily detect design fault, waste of product development time can be minimized. 相似文献
65.
This paper uses a finite dominating set (FDS) to investigate the multi-facility ordered median problem (OMP) in a strongly
connected directed network. The authors first prove that the multi-facility OMP has an FDS in the node set, which not only
generalizes the FDS result provided by Kalcsics, et al. (2002), but also extends the FDS result from the single-facility case
to the multiple case, filling an important gap. Then, based on this FDS result, the authors develop an exact algorithm to
solve the problem. However, if the number of facilities is large, it is not practical to find the optimal solution, because
the multi-facility OMP in directed networks is NP-hard. Hence, we present a constant-approximation algorithm for the p-median problem in directed networks. Finally, we pose an open problem for future research. 相似文献
66.
Zhu P Liu J Bess J Chertova E Lifson JD Grisé H Ofek GA Taylor KA Roux KH 《Nature》2006,441(7095):847-852
Envelope glycoprotein (Env) spikes on AIDS retroviruses initiate infection of host cells and are therefore targets for vaccine development. Though crystal structures for partial Env subunits are known, the structure and distribution of native Env spikes on virions is obscure. We applied cryoelectron microscopy tomography to define ultrastructural details of spikes. Virions of wild-type human immunodeficiency virus 1 (HIV-1) and a mutant simian immunodeficiency virus (SIV) had approximately 14 and approximately 73 spikes per particle, respectively, with some clustering of HIV-1 spikes. Three-dimensional averaging showed that the surface glycoprotein (gp120) 'head' of each subunit of the trimeric SIV spike contains a primary mass, with two secondary lobes. The transmembrane glycoprotein 'stalk' of each trimer is composed of three independent legs that project obliquely from the trimer head, tripod-like. Reconciling available atomic structures with the three-dimensional whole spike density map yields insights into the orientation of Env spike structural elements and possible structural bases of their functions. 相似文献
67.
Frihi Zahrate El Oula Choutri Salah Eddine Barreiro-Gomez Julian Tembine Hamidou 《系统科学与复杂性》2022,35(1):1-17
This paper solves a mean-field type hierarchical optimal control problem in electricity market.The authors consider n-1 prosumers and one producer.The ith prosu... 相似文献
68.
Shrinkage Properties of Wool and Acrylic/Wool Plain Knitted Fabrics Treated with DC109 总被引:1,自引:0,他引:1
This paper examines the effects of shrink - resist treatment, washing cycle and fabric tightness on the shrinkage properties of plain knitted fabrics made from 100% wool, acrylic/wool (50/50) and acrylic/wool (70/30). It was found that shrinkages of both treated and untreated wool fabrics were negatively correlated to fabric tightness and exceeded the IWS shrinkage limits (5% in length and 8 % in area) after 2 - 5A washing cycle. The effect of tightness was not as obvious with acrylic/wool (A/W) fabrics, but the shrinkage was seen to increase with stages of washing cycle for untreated A/W fabrics with some exceeding IWS standard. By applying the DC 109 shrink - resist solvent treatment, it was identified that by with higher percentage of acrylic fibre blended with wool, shrinkage could be reduced considerably and within acceptable limits. 相似文献
69.
70.