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101.
Nader Ebrahimi 《商业与工业应用随机模型》2014,30(3):294-302
In nanoscience and nanotechnology, much attention has been given to the dual problem of designing nanocomponents with novel physical properties and how such nanocomponents can be fabricated. Receiving less attention has been the question of the nanocomponent's reliability; how does a nanocomponent fail and how long does a nanocomponent survive under typical operating conditions? High reliability is necessary to guarantee the advancement and utilization of nanocomponents due to the fact that they account for a high proportion of costs of newly designed nanosystems as well as multiscale systems. A nanocomponent is a component that is made of atoms, and its reliability is determined by these atoms. There are situations where it is hard or impossible to extract information from a nanocomponent about its relationship to its atoms. In this article, we assess the nanocomponent's reliability by using its physical properties. Specifically, it is known that nanocrack growth involves considerable statistical variability and such variability should be accounted for assessing growth. In this paper, we first provide a stochastic nanocrack growth model and then evaluate the reliability of a nanocomponent based on this model. Various properties of this model are obtained. We also evaluate the reliability of a nanocomponent under different assumptions on our proposed growth model. This paper is a modification of the extensive literature on modeling fatigue cracks in materials on a larger scale, applied to nanoscale where growth is not a function of cumulative stress on the component but related to the time to first exceedance of a threshold. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
102.
We prove the classification of joinings for maximal horospherical subgroups acting on homogeneous spaces without any restriction
on the characteristic. Using the linearization technique, we deduce a special case of Raghunathan’s orbit closure conjecture.
In the appendix, quasi-isometries of higher rank lattices in semisimple algebraic groups over fields of positive characteristic
are characterized. 相似文献
103.
Let K be a number field and let A be its ring of integers. Let G be a connected, noncommutative, absolutely almost simple algebraic K-group. If the K-rank of G equals 2, then G(A[t]) is not finitely presented. 相似文献
104.
105.
Khan M. A. Uddin Hannes Orelma Pezhman Mohammadi Maryam Borghei Janne Laine Markus Linder Orlando J. Rojas 《Cellulose (London, England)》2017,24(7):2837-2848
Aerogels prepared from aqueous dispersions of anionic and cationic cellulose nanofibrils (CNFs) were investigated as solid supports for enzymes and silver nanoparticles and to elicit a sustained antibacterial effect. The imparted stabilization in dry conditions was studied with aerogels that were cast after mixing the enzymes with CNFs followed by dehydration (freeze-drying). The activity of lysozyme immobilized in the given CNF system was analyzed upon storage in liquid and air media. In contrast with aqueous solutions of free, unbound enzyme, which lost activity after the first day, the enzyme immobilized physically in unmodified and cationic CNF presented better stability (activity for a longer time). However, the enzyme activity was reduced in the case of anionic CNF, which was prepared by TEMPO-mediated oxidation (TO-CNF). Both humidity and temperature reduced the stability of the enzyme immobilized in the respective CNF aerogel. The antibacterial activity of CNF aerogels carrying lysozyme was also tested against gram-negative and gram-positive bacteria. The results were compared with those obtained from CNF systems loaded with silver nanoparticles (AgNP) after in situ synthesis via UV reduction. Storage in cold or dry conditions preserved the activity and antibacterial performance of enzyme-loaded CNF aerogels. As expected, the lysozyme-containing aerogels showed lower inhibition than the AgNP-containing aerogel. In this latter case, the antibacterial activity depended on the concentration and size of the nanoparticles. Compared to unmodified CNF and TO-CNF, the aerogels prepared with cationic CNF, loaded with either lysozyme or AgNPs, showed remarkably better antibacterial activity. Similar experiments were conducted with horseradish peroxidase, which confirmed, to different degrees, the observations derived from the lysozyme systems. Overall, the results indicate that non-toxic and biodegradable CNF is a suitable support for bio-active materials and is effective in protecting and retaining enzymatic and antibacterial activities. 相似文献
106.
107.
TiO 2 nanorods have been successfully grown into a track-etched polycarbonate (PC) membrane by a particulate sol-electrophoretic deposition from an aqueous medium.The prepared sols had a narrow particle size distribution around 17 nm and excellent stability against aging,with zeta potentials in the range of 47-50 mV at pH 2.It was found that TiO 2 nanorods were grown from dilute aqueous sol with a low,0.1-M concentration.Fourier transform infrared spectroscopy (FT-IR) analysis confirmed that a full conversi... 相似文献
108.
S. F. Mirshojaei M. Gandomkar R. Najafi S. E. Sadat Ebrahimi M. H. Babaei A. Shafiei M. H. Talebi 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):21-25
Cefotaxime, a cephalosporin antibiotic, used to treat bacterial infections was investigated to label with 99mTc. Labeling was performed using sodium dithionite as a reducing agent at 100 °C for 10 min and radiochemical analysis involved
ITLC and HPLC methods. The stability of labeled antibiotic was checked in the presence of human serum at 37 °C up to 24 h.
The maximum radiolabeling yield was 92 ± 2%. Bacterial binding assay was performed with S. aureus and the in vivo distribution was studied in mice. Images showed minimal accumulation in non-target tissues, with an average
target/non-target ratio of 2.89 ± 0.58. 相似文献
109.
We present low complexity models for the transport of passive scalars for environmental applications. The model uses partial observations assimilation. Similitude solutions are proposed in a non symmetric metric based on travel times. The approach does not require the solution of any PDE and is mesh free. Also, the solution can be computed in one point only without computing the whole solution. To cite this article: B. Mohammadi, J.-M. Brun, C. R. Mecanique 334 (2006). 相似文献
110.
This paper develops measures of information for multivariate distributions when their supports are truncated progressively. The focus is on the joint, marginal, and conditional entropies, and the mutual information for residual life distributions where the support is truncated at the current ages of the components of a system. The current ages of the components induce a joint dynamic into the residual life information measures. Our study of dynamic information measures includes several important bivariate and multivariate lifetime models. We derive entropy expressions for a few models, including Marshall-Olkin bivariate exponential. However, in general, study of the dynamics of residual information measures requires computational techniques or analytical results. A bivariate gamma example illustrates study of dynamic information via numerical integration. The analytical results facilitate studying other distributions. The results are on monotonicity of the residual entropy of a system and on transformations that preserve the monotonicity and the order of entropies between two systems. The results also include a new entropy characterization of the joint distribution of independent exponential random variables. 相似文献