Preparation and some properties of cholesterol oxidase from Rhodococcus sp. R14-2

Rhodococcus sp. R14-2, isolated from Chinese Jin-hua ham, produces a novel extracellular cholesterol oxidase (COX). The enzyme was extracted from fermentation broth and purified 53.1-fold based on specific activity. The purified enzyme shows a single polypeptide band on SDS-PAGE with an estimated molecular weight of about 60 kDa, and has a pI of 8.5. The first 10 amino acid residues of the NH2-terminal sequence of the enzyme are A-P-P-V-A-S-C-R-Y-C, which differs from other known COXs. The enzyme is stable over a rather wide pH range of 4.0¿10.0. The optimum pH and temperature of the COX are pH 7.0 and 50°C, respectively. The COX rapidly oxidizes 3ß-hydroxysteroids such as cholesterol and phytosterols, but is inert toward 3¿-hydroxysteroids. Thus, the presence of a 3ß-hydroxyl group appears to be essential for substrate activity. The Michaelis constant (Km) for cholesterol is estimated at 55 ¿M; the COX activity was markedly inhibited by metal ions such as Hg2+ and Fe3+ and inhibitors such as p-chloromercuric benzoate, mercaptoethanol and fenpropimorph. Inhibition caused by p-chloromercuric benzoate, mercuric chloride, or silver nitrate was almost completely prevented by the addition of glutathione. These suggests that -SH groups may be involved in the catalytic activity of the present CO

Determination of material parameters in the chaboche unified viscoplasticty model

An experimental programme of cyclic mechanical testing of a 316 stainless steel, at temperatures up to 600°C, under isothermal conditions, for the identification of material constitutive constants, has been carried out using a thermo-mechanical fatigue (TMF) test machine with induction coil heating. The constitutive model adopted is a modified Chaboche unified viscoplasticity model, which can deal with both cyclic effects, such as combined isotropic and kinematic hardening, and rate-dependent effects, associated with viscoplasticity. The characterisation of 316 stainless steel is presented and compared to results from cyclic isothermal tests. A least squares optimisation algorithm has been developed and implemented for determining the material constants in order to further improve the general fit of the model to experimental data, using the initially obtained material constants as the starting point in this optimisation process. The model predictions using both the initial and optimised material constants are compared to experimental data

Numerical Simulation-Based Optimization of Contact Stress Distribution and Lubrication Conditions in the Straight Worm Drive

Tooth contact area optimization/meshing of the straight worm pair is vital for improving its operation efficiency. Geometric parameters of a worm helicoid were derived via the gear meshing theory using the equations of the instantaneous contact line. The visualization function and powerful computing capability of MATLAB are used for the numerical analysis where the instantaneous contact line distribution is simulated for particular worm drive parameters, which yields the induced curvature and slip angle in the direction of the line. The above results are used for further optimization of the meshing performance of the straight worm gear and identification of its influencing factors. A case study of the particular cylindrical worm gear in compliance with the GB 10085-1988 Standard of China demonstrate that a reasonable selection of worm gear parameters can extend the contact line and the working range of the tooth surface of the worm gear and/or make the contact line distribution along the worm wheel more uniform, thus improving the local meshing performanceОптимизация зубчатой контактной поверхности/зацепление прямолинейной червячной пары определяют повышение эффективности ее эксплуатации. Геометрические параметры червячного геликоида получены с использованием теории зацепления зубчатых колес и уравнения линии мгновенного контакта. Численный анализ основан на функции визуализации и вычислительных возможностях программы MATLAB, что позволяет моделировать распределение на линии мгновенного контакта для специфических параметров червячного привода, создавая вынужденную кривизну и угол скольжения в направлении этой линии. Полученные результаты обеспечивают последующую оптимизацию параметров зацепления прямолинейной червячной передачи и установление определяющих факторов. Пример использования специфической цилиндрической червячной передачи в соответствии со стандартом Китая (GB 10085-1988) показывает, что рациональный выбор параметров этой передачи может увеличить линию контакта, а также расширить рабочий диапазон ее зубчатой поверхности и/или обеспечить более равномерный контакт по червячному колесу, повышая тем самым эффективность локального зацепления

Superconductivity and single crystal growth of Ni0:05TaS2

Superconductivity was discovered in a Ni0:05TaS2 single crystal. A Ni0:05TaS2 single crystal was successfully grown via the NaCl/KCl flux method. The obtained lattice constant c of Ni0:05TaS2 is 1.1999 nm, which is significantly smaller than that of 2H-TaS2 (1.208 nm). Electrical resistivity and magnetization measurements reveal that the superconductivity transition temperature of Ni0:05TaS2 is enhanced from 0.8 K (2H-TaS2) to 3.9 K. The charge-density-wave transition of the matrix compound 2H-TaS2 is suppressed in Ni0:05TaS2. The success of Ni0:05TaS2 single crystal growth via a NaCl/KCl flux demonstrates that NaCl/KCl flux method will be a feasible method for single crystal growth of the layered transition metal dichalcogenides.Comment: 13pages, 6 figures, Published in SS

Recognizing basal cell carcinoma on smartphone‐captured digital histopathology images with a deep neural network

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154530/1/bjd18026.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154530/2/bjd18026_am.pd

Unified order-disorder vortex phase transition in high-Tc superconductors

The diversity of vortex melting and solid-solid transition lines measured in different high-T$_{c}$ superconductors is explained, postulating a unified order-disorder phase transition driven by both thermally- and disorder-induced fluctuations. The temperature dependence of the transition line and the nature of the disordered phase (solid, liquid, or pinned liquid) are determined by the relative contributions of these fluctuations and by the pinning mechanism. By varying the pinning mechanism and the pinning strength one obtains a spectrum of monotonic and non-monotonic transition lines similar to those measured in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$$, YBa$_{2}$Cu$_{3}$O$_{7-\delta}$, Nd$_{1.85}$Ce$_{0.15}$CuO$$, Bi$_{1.6}$Pb$_{0.4}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ and (La$_{0.937}$Sr$_{0.063}$)$_{2}$CuO$_{4}$Comment: To be published in Phys. Rev. B Rapid Com

Genetic characterisation and cytological identification of a male sterile mutant in maize (Zea mays L.)

Male sterile mutants play an important role in the utilisation of crop heterosis. Male sterile plants were found in S5 generations of maize hybrid ZH2, through continuous sib-mating by using the fertile plants in the same population, we obtained a male sterile sibling population K932MS including sterile plants K932S and a fertile plant K932F. The objective of this study was to clarify the genetic characterisation and abortion characteristics by nucleus and cytoplasm effect analyses, cytoplasm grouping, and cytological observation. The results showed that no difference was found between K932S and K932F in the vegetative growth stage, but K932S had no emerging anther or pollen grains. The segregation ratio of fertile plants to sterile plants was 1:1 in the sibling progenies, while it was 3:1 in self-crossing progenies of K932F. The sterility of K932S could be restored among reciprocal progenies when seven normal inbred lines were used as females respectively. The fertility expression of K932S crossed with 30 testers would be changed in different test-crosses and some backcross progenies. The C-type restorer Zifeng-1 (Rf4Rf4) was able to restore the fertility of K932S, and the specific PCR amplification bands of K932MS were consistent with CMSCMo17. The anther of K932S began abortion at dyad with its tapetum expanded radically and vacuolated: this induced abnormality in the shapes of both dyads and tetrads. The microspore could not develop normally, and then it collapsed and gradually disappeared. Hence, K932MS is a C-type cytoplasmic male sterile mutant with a pollen-free, stable inheritance: it has potential application value for further research

Violation of the Mott-Ioffe-Regel Limit: High-temperature Resistivity of Itinerant Magnets Srn+1RunO3n+1 (n=2,3,infinity) and CaRuO3

Srn+1RunO3n+1 represents a class of layered materials whose physical properties are a strong function of the number of Ru-O layers per unit cell, n. This series includes the p-wave superconductor Sr2RuO4 (n=1), enhanced paramagnetic Sr3Ru2O7 (n=2), nearly ferromagnetic Sr4Ru3O10 (n=3) and itinerant ferromagnetic SrRuO3 (n=infinity). In spite of a wide spectrum of physical phenomena, this series of materials along with paramagnetic CaRuO3 shares two major characteristics, namely, robust Fermi liquid behavior at low temperatures and anomalous transport behavior featured by linear temperature dependence of resistivity at high temperature where electron wavepackets are no longer clearly defined. There is no crossover separating such two fundamentally different states. In this paper, we report results of our study that systematically addresses anisotropy and temperature dependence of basal-plane and c-axis resistivity as a function of n for the entire Srn+1RunO3n+1 series and CaRuO3 and for a wide temperature range of 1.7 K<T<900 K. It is found that the anomalous transport behavior correlates with magnetic susceptibility and becomes stronger with decreasing dimensionality. Implications of these results are discussed

Determination of oxygen stoichiometry in the mixed-valent manganites

The possible redox (oxidation reduction) chemical methods for precisely determining the oxygen content in the perovskite manganites including hole-doped La1-xCaxMnOy and electron-doped La1-xTexMnOy compounds are described. For manganites annealed at different temperatures, the oxygen content of the samples was determined by a redox back titration in which the powder samples taken in a quartz crucible were dissolved in (1+1) sulfuric acid containing an excess of sodium oxalate, and the excess sodium oxalate was titrated with permanganate standard solution. The results indicate that the method is effective and highly reproducible. Moreover, the variation of oxygen content is also reflected in significantly affecting the electrical transport property of the samples, which is mainly considered to be closely related to introduce oxygen vacancies in the Mn-O-Mn network.Comment: 13 pages, 1 figure. J. Magn. Magn .Mater (accepted

Correlates of School Children's Handwashing: A Study in Tibetan Primary Schools

Hand hygiene, including handwashing by children, has been reported to contribute to the prevention of various infectious conditions. This study aims to explore the correlates of handwashing behavior among 1690 fourth to sixth grade primary school students in 19 Tibetan primary schools (Golog, Qinghai, China). The theory of reasoned action (TRA) was applied. Data was collected by questionnaire. Structural equation modeling (SEM) analysis showed that students’ attitude (β = 0.22, 95% CI 0.13–0.31) and subjective norms in terms of compliance to teachers’, parents’ and peers’ suggestions to wash hands (β = 0.09, 95% CI 0.01–0.18) were directly associated with students’ handwashing behavior. Students’ knowledge (β = 0.04, 95% CI 0.03–0.07) had an indirect association with handwashing behavior, mediated by students’ attitudes and subjective norms. Subjective norms (β = 0.12, 95% CI 0.07–0.17) were also indirectly correlated with handwashing through students’ attitudes. Therefore, our study supported the theory of reasoned action through our findings that students’ attitude and knowledge, and also attitudes from teachers, parents and peers were correlated with student handwashing behavior. Students reported higher level of compliance to teachers than to their parents and classmates. Based on this information, we recommend teacher-involved participatory hygiene education to promote students’ handwashing behaviors in areas at high risk for infectious diseases that can be prevented by handwashing