Polarization reversal and jump-like domain wall motion in stoichiometric LiTaO 3 produced by vapor transport equilibration

The polarization reversal and domain structure evolution has been studied in stoichiometric lithium tantalate prepared by vapor transport equilibration process. The first in situ visualization of domain kinetics has demonstrated the jump-like motion of few strictly oriented plane domain walls, which leads to short isolated current pulses in the switching current data. The proposed model of jump-like domain wall motion caused by interaction with pinning centers representing the areas with increased value of the threshold field is based on the effect of retardation of bulk screening. The derived formulas were applied successfully for analysis of the field dependence of the total switching time. The durations of wall jumps and wall stays (rest times) extracted from the switching current data are analyzed separately. The deceleration of the wall motion velocity during jump is controlled by the trail of residual depolarization field produced by bound charges and screening charges in the area behind the wall. The duration of the rest time is governed by the bulk screening of residual depolarization field. The value of Hurst exponent 0.75 obtained by fractal analysis of the switching current data has confirmed the essential influence of prehistory on the domain wall motion. The measurements of the coercive field by switching in bipolar triangular pulses in wide range of the field ramp rate have allowed us to extract the record low value of coercive field 60 V/mm for quasi-static polarization reversal. © 2012 American Institute of Physics

Measurement of young's modulus and hardness of Al-50 wt % Sn alloy phases using nanoindentation

The nanoindentation method was used to measure the Young's modulus and hardness of the phases of the alloy Al-50 wt % Sn: α-aluminum and eutectic. Samples are obtained in different ways, i.e., traditionally via the transition of the melt into a homogeneous structural state by heating to a certain temperature, followed by cooling using the cooling rate greater by the order than that of the traditional method and via the addition of 0.06 wt % Ti and 1 wt % Zr to the binary alloy. It has been found that the most significant effect of the Al-50 wt % Sn phases on the Young's modulus is the transition of the melt into a homogeneous structural state and the introduction of Zr into the melt. As part of the mathematical theory of elasticity, a numerical evaluation of the interfacial pressure that arises due to the difference between Young's modulus of α aluminum and eutectic has been performed. The calculation has showed that the extra pressure is nine times less for the alloy formed through the transition of the melt into a homogeneous structural state than for the alloy produced via a traditional way. © 2013 Pleiades Publishing, Ltd

Карнавальный характер современной американской администрации времен Д. Трампа и Д. Байдена

В статье рассматриваются характерные особенности американской администрации в контексте карнавальной политики. Проводится анализ высказываний как ключевых фигур исследования Дональда Трампа и Джо Байдена, так и их сторонников. Рассматривается отношение американского общества к карнавальной политике действующих политиков США. Проводится сопоставление имиджа, создаваемого элитарной части Америки и мнением экспертов, анализирующих и дающих критическую оценку реальным выступлениям и действиям политиков. Также, отслеживается хронологическое изменение мнений среди американской элиты. Для более точного анализа карнавальной политики американской элиты, были рассмотрены не только недавние высказывания действующих политиков Соединённых Штатов в текущем 2022 году, но и некоторые ключевые высказывания в контексте темы статьи, начиная с 2015 года. На основе приведённых примеров, доказывается карнавальный характер современных американских политиков, расхождение слов и действий бывшего и нынешнего лидеров Соединённых Штатов и их администраций. Приводятся подробные анализы ключевых американских политологов и журналистов в контексте несерьёзности администрации США. Анализируется связь теории «глубинного государства» с политикой Дональда Трампа. Выделяется закономерность появления русофобов в администрации Байдена

Assessment of the Use of the Potential of Agricultural Lands in Voronezh Region

The uniqueness and specifics of the land significantly affects both the organization of agricultural production and the rural area management. In order to make well-founded management decisions the economic subjects and public authorities need scientific grounding for assessment of land potential and its use efficiency. The authors suggest using three approaches to land quality and use assessment: agro-climatic potential, land quality score and agricultural production per hectare. Uniting these approaches into single assessment procedure produces a fairly objectively estimation of the economic potential of agricultural land in each selected territory

ИССЛЕДОВАНИЕ ВЛИЯНИЯ СТРУКТУРНОГО СОСТОЯНИЯ РАСПЛАВА НА КРИСТАЛЛИЧЕСКОЕ СТРОЕНИЕ И МЕХАНИЧЕСКИЕ СВОЙСТВА ФАЗ СПЛАВА AL-50 МАС.%SN МЕТОДОМ НАНОИНДЕНТИРОВАНИЯ

Nanoindentation is used to measure Young's modulus, the hardness, the plasticity, and the yield strength of the phases in Al-50 wt % Sn alloy samples prepared by a traditional method and using liquid-state homogenization. The effect of an increase in the cooling rate by an order of magnitude and alloying with 0.06 wt % Ti or 1 wt % Zr on the mechanical properties of the phases in the Al-50 wt % Sn alloy is studied. The most substantial effect on Young's modulus of the phases in the Al-50 wt % Sn alloy is found to be exerted by the homogenization of the metallic liquid and the introduction of zirconium in the alloy melt: the metal forming of an ingot is improved substantially. © 2013 Pleiades Publishing, Ltd