Vibrational and Thermal Properties of ZnX (X=Se, Te): Density Functional Theory (LDA and GGA) versus Experiment

We calculated the phonon dispersion relations of ZnX (X=Se, Te) employing ab initio techniques. These relations have been used to evaluate the temperature dependence of the respective specific heats of crystals with varied isotopic compositions. These results have been compared with mea- surements performed on crystals down to 2 K. The calculated and measured data are generally in excellent agreement with each other. Trends in the phonon dispersion relations and the correspond- ing densities of states for the zinc chalcogenide series of zincblende-type materials are discussed.Comment: 10 pages, submitted to PR

Магнитомягкие композиты на основе порошков железа для создания компонентов двухстаторного комбинированного электродвигателя

An experimental prototype of electric motor on permanent (FeNdB) magnets with switchable magnetic flux with two sectioned stators and a rotor using SMC material based on encapsulated metal powders has been developed. The method of manufacture of magnetic cores by powder metallurgy method on the basis of magnetically soft encapsulated titanium dioxide composites has been developed, including computer modeling of magnetic cores components, creation of tooling for their manufacture by pressing and selection of technological modes of pressing. Press set for manufacturing stator components by pressing in the form of a mold was made of hardened 5XHB steel. With its use magnetic components for twostator combined electric motor are pressed. The main electromagnetic characteristics of the components were measured with an express magnetometer. Complex studies showed that the magnetic components have sufficient strength and the necessary electromagnetic characteristics to create a two-stator combined electric motor of this type. An experimental sample of electric motor with maximum power of 15 kW was created on the basis of manufactured magnetic components. Advantages of composite material over electrical steel and other soft magnetic alloys allow providing their wider application in electric machines in order to increase specific power at high speed of rotation with less losses.Разработан экспериментальный образец электродвигателя с переключаемым магнитным потоком с двумя секционированными статорами и ротором на постоянных (FeNdB) магнитах с применением SMC-материала на основе капсулированных металлических порошков. Создана методика изготовления магнитопроводов на основемагнитомягких капсулированных диоксидом титана композитов методом порошковой металлургии, включающая в себя компьютерное моделирование компонентов магнитопроводов, создание оснастки для их изготовления методом прессования и выбор технологических режимов прессования. Оснастка для компонентов статора методом прессования в виде пресс-формы изготовлена из закаленной стали 5ХHB. С ее применением спрессованы магнитныекомпоненты для двухстаторного комбинированного электродвигателя. Основные электромагнитные характеристики компонентов измерены с помощью экспресс-магнетометра. Комплексные исследования показали, что магнитные компоненты обладают достаточной прочностью и необходимыми электромагнитными характеристиками длясоздания двухстаторного комбинированного данного типа электродвигателя. На основе изготовленных магнитных компонентов создан экспериментальный образец электродвигателя с максимальной расчетной мощностью 15 кВт. Преимущества композиционного материала перед электротехнической сталью и другими магнитомягкими сплавами позволяют обеспечить более широкое их применение в электрических машинах с целью повышения удельной мощности при высокой скорости вращения с меньшими потерями

СТРУКТУРНЫЕ И МАГНИТНЫЕ СВОЙСТВА ТВЕРДЫХ РАСТВОРОВ СИСТЕМЫ АНТИМОНИД КОБАЛЬТА–ТЕЛЛУРИД КОБАЛЬТА

By the method of melting special powder amounts of cobalt antimonide and cobalt telluride in vacuum, the solid solutions alloys of the CoSb1–x Tex system were synthesized with the NiAs structure. X-ray analysis results of the alloys confirmed the formation of a continuous series of solid solutions with a nickel-arsenide-type structure in the system. The constants a of the initial CoSb and CoTe compounds are close in values, which determines the course of the dependence a = f(x) that is practically parallel to the concentration axis. The dependence of the constant c on the concentration increases smoothly from 5.181 Å in CoSb to 5.371 Å in CoTe with a slight deflection to the concentration axis. The alloy density, determined by the hydrostatic weighing in carbon tetrachloride, has a linear dependence on the concentration. The concentration dependence of the micro hardness of the CoSb1–x Tex alloys passes through a weakly expressed maximum in the range of average compositions. Specific magnetization and magnetic susceptibility of the alloys are measured by the ponderomotive method in a magnetic field of 6.8 · 105 A/m in the temperature range 80–1200 K. At the temperature of liquid nitrogen, the value of specific magnetization is maximum (~6,0–6,5 Гс · см3 · г–1) in CoTe and solid solutions based on it. Solid solutions of compositions x = 0.4–0.9 have a magnetic transition temperature exceeding 1200 K. Методом плавления соответствующих количеств порошков соединений антимонида кобальта и теллурида кобальта в вакууме синтезированы сплавы твердых растворов системы CoSb1–x Tex . Результаты рентгеноструктурного анализа сплавов подтвердили образование в системе непрерывного ряда твердых растворов со структурой никель- арсенидного типа. Постоянные а исходных соединений CoSb и CoTe близки по величинам, что определяет практически параллельный оси концентрации ход зависимости a = f(x). Зависимость постоянной с от концентрации плавно возрастает от 5,181 Å у CoSb до 5,371 Å у CoTe с небольшим прогибом к оси концентраций. Плотность сплавов, определенная методом гидростатического взвешивания в тетрахлориде углерода, имеет линейный характер зависимости от концентрации. Концентрационная зависимость микротвердости сплавов системы CoSb1–x Tex проходит через слабо выраженный максимум в области средних составов. Пондеромоторным методом в магнитном поле 6,8 · 105 А/м в интервале температур 80–1200 К измерены удельная намагниченность и магнитная восприимчивость сплавов системы. При температуре жидкого азота величина удельной намагниченности максимальна (~6,0–6,5 Гс · см3 · г–1) у составов CoTe и CoSb0,1Te0,9 и практически равна нулю у CoSb и твердых растворов на его основе. Твердые растворы составов х = 0,4–0,9 обладают температурой магнитного перехода, превышающей 1200 К

Androgen Receptor Drives Cellular Senescence

The accepted androgen receptor (AR) role is to promote proliferation and survival of prostate epithelium and thus prostate cancer progression. While growth-inhibitory, tumor-suppressive AR effects have also been documented, the underlying mechanisms are poorly understood. Here, we for the first time link AR anti-cancer action with cell senescence in vitro and in vivo. First, AR-driven senescence was p53-independent. Instead, AR induced p21, which subsequently reduced ΔN isoform of p63. Second, AR activation increased reactive oxygen species (ROS) and thereby suppressed Rb phosphorylation. Both pathways were critical for senescence as was proven by p21 and Rb knock-down and by quenching ROS with N-Acetyl cysteine and p63 silencing also mimicked AR-induced senescence. The two pathways engaged in a cross-talk, likely via PML tumor suppressor, whose localization to senescence-associated chromatin foci was increased by AR activation. All these pathways contributed to growth arrest, which resolved in senescence due to concomitant lack of p53 and high mTOR activity. This is the first demonstration of senescence response caused by a nuclear hormone receptor

Evaluation of Candidate Reference Genes for Gene Expression Normalization in Brassica juncea Using Real Time Quantitative RT-PCR

The real time quantitative reverse transcription PCR (qRT-PCR) is becoming increasingly important to gain insight into function of genes. Given the increased sensitivity, ease and reproducibility of qRT-PCR, the requirement of suitable reference genes for normalization has become important and stringent. It is now known that the expression of internal control genes in living organism vary considerably during developmental stages and under different experimental conditions. For economically important Brassica crops, only a couple of reference genes are reported till date. In this study, expression stability of 12 candidate reference genes including ACT2, ELFA, GAPDH, TUA, UBQ9 (traditional housekeeping genes), ACP, CAC, SNF, TIPS-41, TMD, TSB and ZNF (new candidate reference genes), in a diverse set of 49 tissue samples representing different developmental stages, stress and hormone treated conditions and cultivars of Brassica juncea has been validated. For the normalization of vegetative stages the ELFA, ACT2, CAC and TIPS-41 combination would be appropriate whereas TIPS-41 along with CAC would be suitable for normalization of reproductive stages. A combination of GAPDH, TUA, TIPS-41 and CAC were identified as the most suitable reference genes for total developmental stages. In various stress and hormone treated samples, UBQ9 and TIPS-41 had the most stable expression. Across five cultivars of B. juncea, the expression of CAC and TIPS-41 did not vary significantly and were identified as the most stably expressed reference genes. This study provides comprehensive information that the new reference genes selected herein performed better than the traditional housekeeping genes. The selection of most suitable reference genes depends on the experimental conditions, and is tissue and cultivar-specific. Further, to attain accuracy in the results more than one reference genes are necessary for normalization

Reference Gene Selection for Quantitative Real-time PCR Normalization in Quercus suber

The use of reverse transcription quantitative PCR technology to assess gene expression levels requires an accurate normalization of data in order to avoid misinterpretation of experimental results and erroneous analyses. Despite being the focus of several transcriptomics projects, oaks, and particularly cork oak (Quercus suber), have not been investigated regarding the identification of reference genes suitable for the normalization of real-time quantitative PCR data. In this study, ten candidate reference genes (Act, CACs, EF-1α, GAPDH, His3, PsaH, Sand, PP2A, ß-Tub and Ubq) were evaluated to determine the most stable internal reference for quantitative PCR normalization in cork oak. The transcript abundance of these genes was analysed in several tissues of cork oak, including leaves, reproduction cork, and periderm from branches at different developmental stages (1-, 2-, and 3-year old) or collected in different dates (active growth period versus dormancy). The three statistical methods (geNorm, NormFinder, and CV method) used in the evaluation of the most suitable combination of reference genes identified Act and CACs as the most stable candidates when all the samples were analysed together, while ß-Tub and PsaH showed the lowest expression stability. However, when different tissues, developmental stages, and collection dates were analysed separately, the reference genes exhibited some variation in their expression levels. In this study, and for the first time, we have identified and validated reference genes in cork oak that can be used for quantification of target gene expression in different tissues and experimental conditions and will be useful as a starting point for gene expression studies in other oaks

Updates on p53: modulation of p53 degradation as a therapeutic approach

The p53 pathway is aberrant in most human tumours with over 50% expressing mutant p53 proteins. The pathway is critically controlled by protein degradation. Here, we discuss the latest developments in the search for small molecules that can modulate p53 pathway protein stability and restore p53 activity for cancer therapy