Influence of various plasma treatment on the properties of carbon nanotubes for composite applications

In present work, the effects of hydrogen and oxygen plasma treatments on the structural properties of carbon nanotubes (CNTs) synthesized by catalytic CVD (Chemical Vapor Deposition) have been systematically investigated. Field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy were used to characterize the microstructural changes of the CNTs. The oxygen plasma treatment resulted in that the nanoparticles were appeared at the surface of CNTs. At high r.f. power (300 Watt), the microstructure of CNT was changed from nanotube type to nano particles. Long plasma treatment time changed the CNT morphology dramatically. For hydrogen plasma, however, there was no change in microstructure of CNT From the Raman analysis, the crystallinity of CNT was deteriorated by the plasma treatment, regardless of plasma power, treatment time, and gas types. The CNTs treated in oxygen plasma for 90 min showed excellent dispersion properties in aqueous solution.     

催化重整装置再接触方案探讨

对催化重整装置再接触系统的三种流程：低温再接触,常温再接触和常温再接触＋吸收,从产品收率,公用工程消耗,设备投资和经济效益方面进行了比较,结论是：对于产氢去PSA的重整装置,若PSA的尾气只作为燃料气时,低温再接触流程优于常温再接触流程;若PSA尾气还要去轻烃回收,则再接触可采用常温再接触,不必采用低温再接触。     

Mechanisms of positive gate-bias stress induced instabilities in CMOS transistors

Increase of positive gate oxide charge and interface trap densities has been shown to be responsible for positive gate-bias stress induced instabilities of threshold voltage and gain factor in Al-gate and Si-gate CMOS transistors. The electron tunneling from trivalent-silicon and/or oxygen-vacancy defects into the oxide conduction band has been established as a mechanism of the positive gate oxide charge creation. The creation of interface traps, appearing due to interfacial trivalent silicon atoms, has been related to the reaction between interfacial Si-H or Si-OH groups and the positive gate oxide charge built up close to the oxide-silicon interface.     

Optimal convex error estimators for classification

A cross-validation error estimator is obtained by repeatedly leaving out some data points, deriving classifiers on the remaining points, computing errors for these classifiers on the left-out points, and then averaging these errors. The 0.632 bootstrap estimator is obtained by averaging the errors of classifiers designed from points drawn with replacement and then taking a convex combination of this “zero bootstrap” error with the resubstitution error for the designed classifier. This gives a convex combination of the low-biased resubstitution and the high-biased zero bootstrap. Another convex error estimator suggested in the literature is the unweighted average of resubstitution and cross-validation. This paper treats the following question: Given a feature-label distribution and classification rule, what is the optimal convex combination of two error estimators, i.e. what are the optimal weights for the convex combination. This problem is considered by finding the weights to minimize the MSE of a convex estimator. It also considers optimality under the constraint that the resulting estimator be unbiased. Owing to the large amount of results coming from the various feature-label models and error estimators, a portion of the results are presented herein and the main body of results appears on a companion website. In the tabulated results, each table treats the classification rules considered for the model, various Bayes errors, and various sample sizes. Each table includes the optimal weights, mean errors and standard deviations for the relevant error measures, and the MSE and MAE for the optimal convex estimator. Many observations can be made by considering the full set of experiments. Some general trends are outlined in the paper. The general conclusion is that optimizing the weights of a convex estimator can provide substantial improvement, depending on the classification rule, data model, sample size and component estimators. Optimal convex bootstrap estimators are applied to feature-set ranking to illustrate their potential advantage over non-optimized convex estimators.     

An electrochemical Nafion® matrix oxygen sensor and the evaluation of oxygen permeation in coated films

A Nafion® matrix was used to prepare a small and simple oxygen sensor whose sensing electrode and counter electrode were made by r.f. sputtering of platinum deposits on both sides of the Nafion® membrane. The sensing current varied linearly with oxygen partial pressure. This sensor enabled an estimation of oxygen permeation in coated films at working conditions. The present method clarifies the correspondence between the permeation rate through the clear layer and the degree of deterioration of underlayered paint film.[/p]     

Passive transfer of insulitis from the "BB" rat to the nude mouse

The "BB" rat spontaneously develops insulitis, and an insulin-dependent diabetic syndrome like that in man. Lymphocytes were isolated from blood and spleen of newly-detected "BB" diabetic rats and injected intraperitoneally (IP) into athymic nude mice. Of 72 mice receiving single injections 37% showed insulitis, with 13% of islets examined being affected, and mean intensity of 1.9 +/- 0.3 (on a scale of 0 to 3). In 12 mice receiving 3 separate injections of pooled blood and spleen lymphocytes, 58% showed insulitis, with 17% of islets affected, and mean intensity 2.5 +/- 0.3. Of 45 control mice either untreated, injected IP with saline, or injected with cells from nondiabetic control rats, only one showed mild insulitis. No random or post IP glucose hyperglycemia was observed. Thus, 1) passive transfer of insulitis has been achieved; 2) insulitis may be present without glucoregulatory disturbances; 3) the pancreatic B cell need not display abnormal membrane structure for it to be susceptible to involvement in the cell-mediated immune process; and 4) detailed studies are required to define the relationship of administered lymphocytes to the observed pathology.     

绝缘子表面防污处理层的形成机理及老化试验研究

本文通过XPS分析,提出了绝缘子表面处理层的形成机理及表面结构,从理论上论证了具有防污处理层的绝缘子在物理和电气方面的优良特性。同时,通过有关光老化试验研究,探索在加速光老化时,绝缘子交流污闪电压及泄漏电流的变化趋势。     

Dietary intake of fish,n-3 polyunsaturated fatty acids and risk of hip fracture: A systematic review and meta-analysis on observational studies

Previous studies have shown that fish consumption and dietary intake of n-3 polyunsaturated fatty acids (n-3 PUFAs) are associated with hip fracture; however, findings were conflicting. The present review aimed to summarize the current evidence on the association of fish consumption and dietary intake of n-3 PUFAs with hip fracture. The online databases of PubMed, ISI Web of Science, Scopus, ProQuest, Science Direct and Embase were searched until August 2017 for related publications using relevant keywords. To pool data, either a fixed-effects model or random-effects models were used. Cochran's Q tests were used to assess heterogeneity between studies. In total, 10 studies (7 prospective and 3 case-control studies) were included in this systematic review, and 9 studies with total sample size of 292657 participants were included in the meta-analysis. The age of participants was 20 years or older. Combining 8 effect sizes from 4 prospective studies and 2 case-control studies revealed a significant inverse association between fish consumption and risk of hip fracture (pooled effect size: 0.88, 95% CI: 0.79-0.98, P = 0.02). Although this relationship became non-significant in prospective studies, a significant inverse association was found in prospective studies with sample size of 10000 individuals or more, and studies that considered body mass index as a covariate. Furthermore, dietary intake of n-3 PUFAs was inversely associated with risk of hip fracture (pooled effect size: 0.89, 95% CI: 0.80-0.99, P = 0.02). Also, such relationship was seen after excluding one case-control study and combining effect sizes only from prospective studies (pooled effect size: 0.88, 95% CI: 0.80-0.98, P = 0.02). In conclusion, we found that fish consumption and dietary intake of n-3 PUFAs might have protective effects on bone health and decline the risk of hip fracture.     

Enhanced electrocatalytic activity of nickel particles electrodeposited onto poly (m-toluidine) film prepared in presence of CTAB surfactant on carbon paste electrode for formaldehyde oxidation in alkaline medium

In this work, carbon paste electrode is coated with poly (m-toluidine) film by potentiodynamic electropolymerization of m-toluidine monomer in the presence of cetyltrimethyl ammonium bromide (CTAB-PMT/MCPE). Then electrolysis at fixed potential (−1.0 V versus reference electrode for 15 min) is employed for electrodepositing of Ni from 1.5 M NiSO₄ acidic solution at the surface of polymer-modified electrode for preparation of Ni/CTAB-PMT/MCPE. The general electrochemical behaviors of these modified electrodes are characterized by cyclic voltammetry in alkaline media. In alkaline medium (i.e. NaOH 0.1 M) a good redox behavior of Ni(III)/Ni(II) couple at the surface of these electrodes can be observed. The nickel particles electrodeposited at the surface of Ni/CTAB-PMT/MCPE exhibits a significant electrocatalytic activity towards oxidation of formaldehyde. Moreover, the effects of various parameters such as concentration of CTAB, concentration of formaldehyde, film thickness and monomer concentration on the electrooxidation of formaldehyde as well as long-term stability of the Ni/CTAB-PMT/MCPE have also been investigated.     

4流大方坯45 t中间包流场的物理模拟和冶金效果

通过几何相似比1:3的水模型对钢厂4流410 mm × 530 mm大方坯连铸机的不同结构的40～50t中间包进行流场、温度场以及流动特征的研究,并得出最佳控流装置。研究结果表明,为满足4流大方坯中间包对流场的要求,有通道式感应加热装置的中间包与无通道式感应加热装置的中间包优化出的最佳控流装置不同。对于无通道式感应加热装置的中间包,采用最佳方案(湍流控制器+带导流孔的"V"型挡渣墙+挡坝组合的控流方式),延长了近流水口响应时间及平均停留时间,各水口钢液的流动模式趋于一致,中间包内钢液的流动特征得到明显改善。生产40Cr钢实践表明,可连浇8炉,各水口最大温差为4℃,中间包钢液中T[O]约为10×10^-6。