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排序方式: 共有5171条查询结果,搜索用时 203 毫秒
991.
Rahul V. Manek Olobayo O. Kunle Martins O. Emeje Philip Builders Goparaju V. Rama Rao Gabriel P. Lopez William M. Kolling 《Starch - St?rke》2005,57(2):55-61
The purpose of this study was to elucidate functional properties of starch granules obtained from tubers of Tacca leontopetaloides and compare them to a commercially available maize starch. Scanning electron microscopy (SEM), particle size analysis, X‐ray powder diffraction (XRPD), gravimetric moisture sorption, and differential scanning calorimetry (DSC) were used to characterize the samples. Tacca starch exhibited a monomodal distribution of irregularly shaped granules with a mean particle size of 2.64 µm. The spherulites of both samples indicated an A‐type pattern, with the degree of crystallinity estimated to be 35% for tacca starch and 38% for maize starch. The moisture sorption profile of both samples was analyzed according to the Guggenheim, Anderson and de Boer (GAB) equation. GAB analysis estimated the monolayer coverage for tacca and maize starch to be 0.0928 g/g and 0.0856 g/g, respectively. The gelatinization parameters of tacca starch were found to be 65.57 – 68.56 – 73.10°C while that of maize starch were 67.30 – 70.97 – 76.25°C. The results of DSC studies indicate that the associative forces that stabilize the granule structure in tacca starch are weaker than those in maize starch. The results obtained in this study establish the fundamental characteristics of tacca starch and suggest that further exploration of its potential for use in a variety of fields is warranted. 相似文献
992.
Yang Xiao Haizhon Li C. L. Philip Chen Bin Wang Yi Pan 《Wireless Communications and Mobile Computing》2005,5(2):219-243
Adaptive multimedia services are very attractive since resources in wireless/mobile networks are relatively scarce and widely variable, and more importantly the resource fluctuation caused by mobility and channel fading can be mitigated using adaptive services. Therefore, there are extensive research activities on Quality of Service (QoS), call admission control, as well as bandwidth degradation and adaptation for adaptive multimedia services in wireless/mobile networks in recent years. However, fairness of bandwidth degradation has largely been ignored in previous work and remains an important issue in adaptive multimedia service provisioning. In this paper, we propose and study proportional degradation service provisioning in wireless/mobile networks that offer multiple classes of adaptive multimedia services. The proposed proportional degradation fairness model guarantees the proportional bandwidth degradation among different classes of services. Two proportional degradation scenarios are studied in this paper. In the first scenario, we study the proportional degradation provisioning with two QoS parameters for adaptive multimedia: the degradation ratio (DR) and the degradation degree (DD). In the second scenario, we study the proportional degradation provisioning with a new QoS parameter for adaptive multimedia: the degradation area (DA). For each scenario, based on the QoS parameters, proportional degradation adaptation algorithms are proposed to approximate the proportional degradation model, to fairly adapt calls' degradations, to utilize the system resource efficiently, as well as to optimize QoS parameters. Performance studies show that in the first scenario, proportional DR has been achieved very well, whereas proportional DD has not been well achieved. In other words, DR outperforms DD in terms of proportional degradation. In the second scenario, proportional DA has been well achieved. Furthermore, bandwidth resources have been efficiently utilized and DA has been minimized. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
993.
Philip Schulz Leah L. Kelly Paul Winget Hong Li Hyungchul Kim Paul F. Ndione Ajaya K. Sigdel Joseph J. Berry Samuel Graham Jean‐Luc Brédas Antoine Kahn Oliver L. A. Monti 《Advanced functional materials》2014,24(46):7381-7389
The interfacial electronic structure between oxide thin films and organic semiconductors remains a key parameter for optimum functionality and performance of next‐generation organic/hybrid electronics. By tailoring defect concentrations in transparent conductive ZnO films, we demonstrate the importance of controlling the electron transfer barrier at the interface with organic acceptor molecules such as C60. A combination of electron spectroscopy, density functional theory computations, and device characterization is used to determine band alignment and electron injection barriers. Extensive experimental and first principles calculations reveal the controllable formation of hybridized interface states and charge transfer between shallow donor defects in the oxide layer and the molecular adsorbate. Importantly, it is shown that removal of shallow donor intragap states causes a larger barrier for electron injection. Thus, hybrid interface states constitute an important gateway for nearly barrier‐free charge carrier injection. These findings open new avenues to understand and tailor interfaces between organic semiconductors and transparent oxides, of critical importance for novel optoelectronic devices and applications in energy‐conversion and sensor technologies. 相似文献
994.
访谈中菲利普·乌尔施布隆首先讨论了当前历史性面临的危机,并得出"建筑理论已失去它的自主性"的观点.他认为当代理论已不存在中心化的大师理论,而是呈现出多元化的概念,恰如米克·巴尔的"微型理论"般运作.基于巴尔关于"概念旅行"的理论,他探讨了全球化语境下建筑教育的新机遇,最后由此出发分析中国与西方国家当代建筑教育之间的相互... 相似文献
995.
Philip C. Trackman Yaser Peymanfar Sayon Roy 《International journal of molecular sciences》2022,23(9)
Lysyl oxidases are multifunctional proteins derived from five lysyl oxidase paralogues (LOX) and lysyl oxidase-like 1 through lysyl oxidase-like 4 (LOXL1–LOXL4). All participate in the biosynthesis of and maturation of connective tissues by catalyzing the oxidative deamination of lysine residues in collagens and elastin, which ultimately results in the development of cross-links required to function. In addition, the five LOX genes have been linked to fibrosis and cancer when overexpressed, while tumor suppression by the propeptide derived from pro-LOX has been documented. Similarly, in diabetic retinopathy, LOX overexpression, activity, and elevated LOX propeptide have been documented. The proteolytic processing of pro-forms of the respective proteins is beginning to draw attention as the resultant peptides appear to exhibit their own biological activities. In this review we focus on the LOX paralogue, and what is known regarding its extracellular biosynthetic processing and the still incomplete knowledge regarding the activities and mechanisms of the released lysyl oxidase propeptide (LOX-PP). In addition, a summary of the roles of both LOX and LOX-PP in diabetic retinopathy, and brief mentions of the roles for LOX and closely related LOXL1 in glaucoma, and keratoconus, respectively, are included. 相似文献
996.
The experimental investigations of the effect of contact time/temperature on initiating the cook-off using 7.62 mm calibre cartridge cases (CC) were conducted previously. These cartridges were filled with commercial off-the-shelf (COTS) double based (DB) propellant (Bulls Eye) and were loaded in a hot chamber. The thermal explosion temperature is of great significance to both weapon designers and safety inspectors as it provides the operational limit and safe operating temperature. For CC under test, it was found that the cook-off temperatures of this propellant were encountered with the heat transfer profile of the simulated gun barrel between 151.4 ℃ and 153.4 ℃, with a reaction occurring in less than 300 s after the round was chambered. Usefully, each experiment was found to be consistent and repeatable. 相似文献
997.
The effects that adsorbed precursor surface diffusion has on electron beam induced deposition are explored via a three-dimensional Monte Carlo simulation. Initially the growth rate and resolution are compared for a common set of deposition conditions with a variable surface diffusion coefficient ranging from 0 to 1 × 10(-8)?cm(2)?s(-1). The growth rate and resolution are shown to both be enhanced as the growth changes from a mass transport limited regime to a reaction rate limited regime. The complex interplay between the vertical growth rate, the lateral growth rate, the interaction volume and the adsorbed and diffused precursor species are discussed. A second scenario is also simulated in which only gas diffused from a constant source at the perimeter of the simulation boundary is assumed (no gas phase adsorption). At low diffusion coefficients, the diffusing gas is consumed by secondary and backscattered electrons and experimentally observed ring-like structures are generated. At higher diffusion coefficients, the diffusion length is sufficient for the precursor atoms to diffuse to the center (and up the pillar sidewalls) to generate nanowires. 相似文献
998.
Intramyocardial Inflammation after COVID-19 Vaccination: An Endomyocardial Biopsy-Proven Case Series
Christian Baumeier Ganna Aleshcheva Dominik Harms Ulrich Gross Christian Hamm Birgit Assmus Ralf Westenfeld Malte Kelm Spyros Rammos Philip Wenzel Thomas Münzel Albrecht Elssser Mudather Gailani Christian Perings Alae Bourakkadi Markus Flesch Tibor Kempf Johann Bauersachs Felicitas Escher Heinz-Peter Schultheiss 《International journal of molecular sciences》2022,23(13)
Myocarditis in response to COVID-19 vaccination has been reported since early 2021. In particular, young male individuals have been identified to exhibit an increased risk of myocardial inflammation following the administration of mRNA-based vaccines. Even though the first epidemiological analyses and numerous case reports investigated potential relationships, endomyocardial biopsy (EMB)-proven cases are limited. Here, we present a comprehensive histopathological analysis of EMBs from 15 patients with reduced ejection fraction (LVEF = 30 (14–39)%) and the clinical suspicion of myocarditis following vaccination with Comirnaty® (Pfizer-BioNTech) (n = 11), Vaxzevria® (AstraZenica) (n = 2) and Janssen® (Johnson & Johnson) (n = 2). Immunohistochemical EMB analyses reveal myocardial inflammation in 14 of 15 patients, with the histopathological diagnosis of active myocarditis according the Dallas criteria (n = 2), severe giant cell myocarditis (n = 2) and inflammatory cardiomyopathy (n = 10). Importantly, infectious causes have been excluded in all patients. The SARS-CoV-2 spike protein has been detected sparsely on cardiomyocytes of nine patients, and differential analysis of inflammatory markers such as CD4+ and CD8+ T cells suggests that the inflammatory response triggered by the vaccine may be of autoimmunological origin. Although a definitive causal relationship between COVID-19 vaccination and the occurrence of myocardial inflammation cannot be demonstrated in this study, data suggest a temporal connection. The expression of SARS-CoV-2 spike protein within the heart and the dominance of CD4+ lymphocytic infiltrates indicate an autoimmunological response to the vaccination. 相似文献
999.