THERMAL-INDUCED DOMAIN PROCESSES IN TRIGLYCINE SULFATE CRYSTALS WITH CHROMIUM IMPURITIES

В работе представлены результаты исследований термоиндуцированных доменных процессов в хромсодержащих кристаллах триглицинсульфата. Показано, что изменение температуры кристаллов ТГС: Cr в отсутствие внешних электрических полей сопровождается перестройкой доменной структуры, которая наиболее интенсивно происходит в области фазового перехода. Деполяризующее поле величиной ~1,4·10 В·м, которое порождается градиентным изменением температуры образца, вызывает процесс переключения его доменной структуры. В неотожженных кристаллах при концентрациях примеси, превышающих 5·10 вес. % процессы переключения затруднены, а интенсивность термоиндуцированных доменных процессов существенно ниже аналогичных для образцов с меньшим содержанием примеси. На интенсивность процессов переключения кристаллов ТГС: Cr существенное влияние оказывает скорость их нагревания. Зависимости интегрального числа скачков переполяризации от скорости нагревания образцов N = f (V) носят экстремальный характер. Экстремумы кривых N = f (V) лежат в интервалах скоростей (0,2-0,8) K·c. Доменная структура кристаллов ТГС:Cr состоит из матрицы основного домена, линзовидных и ламелеобразных доменов. Под воздействием электронного пучка наблюдается эволюция доменной структуры, сопровождающаяся ростом доменов, их слиянием и переключением образца. Высокотемпературный отжиг кристаллов приводит к их полидоменизации. The article presents the results of studies of thermally induced domain processes in chromium-containing crystals of triglycine sulfate (TGS). It is shown that a change in the temperature of TGS: Cr crystals in the absence of external electric fields is accompanied by a rearrangement of the domain structure, that occurs most intensively in the region of the phase transition. A depolarizing field of ~1,4·10 V·m, which is generated by a gradient change in the temperature of the sample, causes the process of switching its domain structure. In unannealed crystals at impurity concentrations exceeding 5·10 wt.%, switching processes are hindered, and the intensity of thermally induced domain processes is significantly lower than that for samples with a lower impurity content. The intensity of the switching processes of TGS: Cr crystals is significantly influenced by the rate of their heating. The dependences of the integral number of polarization-reversal jumps on the heating rate of the samples N = f (V) are extreme. The extrema of the N = f (V) curves lie in the rate intervals (0,2 - 0,8) K·c. The domain structure of TGS: Cr crystals consists of a matrix of the main domain, lenticular and lamellar domains. Evolution of the domain structure is observed under the influence of an electron beam, accompanied by the growth of domains, their coalescence, and sample switching. High-temperature annealing of crystals leads to their polydomenization.

Microstructure analysis and crack nucleation in TWIP steel tube at expansive deformation

The expansion test of twinning induced plastic (TWIP) steel tube was carried out at room temperature. Cracks appeared inside the tube edge when TWIP steel tube expands by 15.6%. The microstructure evolution, deformation mechanism and crack generation of TWIP steel after expansion were investigated by XDR OM TEM and EBSD. The results show that TWIP steel tube still austenite phase after expansion at room temperature; a great deal of dislocations are gathered around the grain boundaries and twin boundaries, the integral number of twins is high, and the mechanism of expansion deformation is the joint action of dislocations slip and deformation twins; Twins produce a large number of finer secondary or even multiple twins, intersecting each other; After expansion, the silk texture with direction of <111>∥X0 dominated by rotating brass texture {110}<111> is gradually produced through grain deformation and rotation; The proportion of small angle grain boundaries increased greatly; It is deduced that the criterion of crack nucleation is based on the difference between the dislocation pile-up energy (DPE) and the crack nucleation energy (CNE), and the expansion deformation process of TWIP steel satisfies the condition of crack nucleation.

Large genotype–phenotype study in carriers of D4Z4 borderline alleles provides guidance for facioscapulohumeral muscular dystrophy diagnosis

Facioscapulohumeral muscular dystrophy (FSHD) is a myopathy with prevalence of 1 in 20,000. Almost all patients affected by FSHD carry deletions of an integral number of tandem 3.3 kilobase repeats, termed D4Z4, located on chromosome 4q35. Assessment of size of D4Z4 alleles is commonly used for FSHD diagnosis. However, the extended molecular testing has expanded the spectrum of clinical phenotypes. In particular, D4Z4 alleles with 9–10 repeat have been found in healthy individuals, in subjects with FSHD or affected by other myopathies. These findings weakened the strict relationship between observed phenotypes and their underlying genotypes, complicating the interpretation of molecular findings for diagnosis and genetic counseling. In light of the wide clinical variability detected in carriers of D4Z4 alleles with 9–10 repeats, we applied a standardized methodology, the Comprehensive Clinical Evaluation Form (CCEF), to describe and characterize the phenotype of 244 individuals carrying D4Z4 alleles with 9–10 repeats (134 index cases and 110 relatives). The study shows that 54.5% of index cases display a classical FSHD phenotype with typical facial and scapular muscle weakness, whereas 20.1% present incomplete phenotype with facial weakness or scapular girdle weakness, 6.7% display minor signs such as winged scapula or hyperCKemia, without functional motor impairment, and 18.7% of index cases show more complex phenotypes with atypical clinical features. Family studies revealed that 70.9% of relatives carrying 9–10 D4Z4 reduced alleles has no motor impairment, whereas a few relatives (10.0%) display a classical FSHD phenotype. Importantly all relatives of index cases with no FSHD phenotype were healthy carriers. These data establish the low penetrance of D4Z4 alleles with 9–10 repeats. We recommend the use of CCEF for the standardized clinical assessment integrated by family studies and further molecular investigation for appropriate diagnosis and genetic counseling. Especially in presence of atypical phenotypes and/or sporadic cases with all healthy relatives is not possible to perform conclusive diagnosis of FSHD, but all these cases need further studies for a proper diagnosis, to search novel causative genetic defects or investigate environmental factors or co-morbidities that may trigger the pathogenic process. These evidences are also fundamental for the stratification of patients eligible for clinical trials. Our work reinforces the value of large genotype–phenotype studies to define criteria for clinical practice and genetic counseling in rare diseases.

Spacer acquisition by Type III CRISPR–Cas system during bacteriophage infection of Thermus thermophilus

Type III CRISPR–Cas systems provide immunity to foreign DNA by targeting its transcripts. Target recognition activates RNases and DNases that may either destroy foreign DNA directly or elicit collateral damage inducing death of infected cells. While some Type III systems encode a reverse transcriptase to acquire spacers from foreign transcripts, most contain conventional spacer acquisition machinery found in DNA-targeting systems. We studied Type III spacer acquisition in phage-infected Thermus thermophilus, a bacterium that lacks either a standalone reverse transcriptase or its fusion to spacer integrase Cas1. Cells with spacers targeting a subset of phage transcripts survived the infection, indicating that Type III immunity does not operate through altruistic suicide. In the absence of selection spacers were acquired from both strands of phage DNA, indicating that no mechanism ensuring acquisition of RNA-targeting spacers exists. Spacers that protect the host from the phage demonstrate a very strong strand bias due to positive selection during infection. Phages that escaped Type III interference accumulated deletions of integral number of codons in an essential gene and much longer deletions in a non-essential gene. This and the fact that Type III immunity can be provided by plasmid-borne mini-arrays open ways for genomic manipulation of Thermus phages.

Cross section determination for TAD materials in quasi mono-energetic neutron spectrum from p(Li) reaction

Threshold activation detectors (TAD) are of great importance for a determination of neutron energy spectra and flux density. For different sources, it is necessary to choose the right combination of materials that cover the estimated spectra. Several different materials were irradiated in a quasi-monoenergetic neutron field with 29.1 MeV peak neutrons energy in the CANAM facility. Neutrons were produced in p + Li-7 reaction in a thin target and the foils were situated in the proton beam axis and close geometry to the Li target. The integral number of protons was established from accelerator telemetry and lithium target activation measurements after the experiment. During the experiment, one long irradiation was done for following foils: Al, Au, Bi, Co, Cu, Fe, In, Mn, Pb, Ta, V, Y and four short irradiations for foils: Cu, Fe, In, Ta, V, W, Y. The foils were irradiated in a sandwich configuration, sorted by cross-section where the materials with higher cross-section were placed in the back of the sandwich. Neutrons produced in the p + Li-7 reaction have a quasi mono-energetic spectrum which provides a suitable basis for cross-section determination. Experimental results were calculated for (n,xn), (n,p) and (n,α) reactions via the dosimetry foils activation method including a gamma-ray spectroscopy method. Several important spectroscopic corrections have to be applied to increase the accuracy of the obtained results, including neutron background suppression. Experimental data will be submitted to the EXFOR database.

Stability Analysis of Centerless Grinding with Loss of Contact Nonlinearity

The paper presents a novel geometrical stability analysis of centerless grinding that takes into account the nonlinearity associated to wheel-workpiece detachment during lobes formation. Even though the rounding mechanism in centerless grinding has been studied since more than fifty years, stability analysis has been carried out applying stability criteria for linear systems (e.g., Nyquist) on a process model that neglects actual removal “clipping” due to wheel-workpiece detachment. This model limitation is usually overcome by considering only an integer number of lobes, supporting the restriction by the claim that a non-integral number of waves is less likely to build up since the waviness must be constantly removed and replaced by a succeeding wave, which is constantly moving around the workpiece. In this work, the nonlinearity entailed by removal clipping is explicitly taken into account and, by harmonic linearization, represented by a double input describing function (DIDF). Applying the Nyquist criterion on the resulting equivalent delayed system, the paramount instability associated to a quasi-integer number of lobes emerges naturally, without requiring additional assumptions. Moreover, it is shown that the nonlinearity due to wheel-workpiece detachment does not produce a limit cycle in a reasonable operation time. The results delivered by the proposed approach are verified by numeric simulations and positively compared to the relevant literature. The proposed formulation can be easily extended to consider also machine structure dynamics, thus increasing, even in this case, the accuracy of the stability analysis provided by the standard approach.

Impact of the Chamber Shape on a Soft Actuator Mechanism to Mimic the Esophageal Swallowing Process

A physical prototype of a human esophagus has been developed for reproducing the human swallowing process with the aim of studying various disorders that impair its function as well as for the development of new foods and technologies for their treatment. Several studies related to the peristalsis phenomena have been conducted in recent years by studying the effect of different parameters defining the peristaltic wave. Mathematical models have been developed to investigate the impact of an integral and a non-integral number of waves during the swallowing of food stuff such as jelly, tomato puree, among others. Swallowing through the esophagus has not only been studied numerically but also reported by using a pneumatic soft actuators. In the present work, the development of a soft actuator mechanism to reproduce the peristaltic wave as the one reported by F.J. Chen et. al. 2014 is described. Such a mechanism consists of a rubber structure that contains an array of chambers actuated by pressurized air to generate the peristaltic wave. The final chamber shape was determined after an iterative process, which involves the elastomer properties, different chamber shapes, finite element analysis and image processing. The characterization of the developed peristaltic mechanism was made by correlating a theoretical study of swallowing peristaltic model and the waveform obtained from the X-ray radiography analysis as the mechanism is actuated. As result, the soft actuator mechanism can reproduce a peristaltic waveform with a correlation coefficient near to 0.9 with respect to the mathematical model reported in literature. In addition, the manufacturing process based on additive manufacturing technologies is also presented.

Доменный эпитаксиальный рост сегнетоэлектрических пленок титаната бария-стронция на сапфире

A model of the epitaxial growth of crystalline multicomponent films on single-crystal substrates with a domain correspondence is presented using a solid solution of barium strontium titanate on sapphire substrates ( r cut). The domain epitaxial growth suggests the matching of the lattice planes of the film and the substrate having similar structures by comparison of domain multiple of an integral number of the interplanar spacings. Variation of the component composition of the solid solution enables changes in the domain size in the range sufficient for epitaxial growth. This method can be used to project the epitaxial growth of films of various solid solutions on single-crystal substrates.

Stability and resonance conditions of second-order fractional systems

The interest of studying fractional systems of second order in electrical and mechanical engineering is first illustrated in this paper. Then, the stability and resonance conditions are established for such systems in terms of a pseudo-damping factor and a fractional differentiation order. It is shown that a second-order fractional system might have a resonance amplitude either greater or less than one. Moreover, three abaci are given allowing the pseudo-damping factor and the differentiation order to be determined for, respectively, a desired normalized gain at resonance, a desired phase at resonance, and a desired normalized resonant frequency. Furthermore, it is shown numerically that the system root locus presents a discontinuity when the fractional differentiation order is an integral number.

New model of understanding income distribution through graduation of normalized Gini Mean Difference

<p>This work covers such a topical problem as the study of income and wealth inequality. It introduces the notion of “graduation”, i.e. rate of wage rate scale customary at time wage system. Graduation means introduction of the index m as a degree of the polynomial based on which the wage rate scale is distributed. In other words, using m allows to graduate Gini mean difference (0&lt;G&lt;1) by assigning integral number or fraction m, 0&lt;m&lt;∞ to every value of Gini index. Similarly, for each m we can calculate and estimate corresponding normalized Gini mean difference (the analog of Gini index used for simplicity of calculations).<br />Note that in this case we are not talking about distribution in real society, but in the simplest model of this society – a metaphoric community with only one person at each income level. This way we get the most distinct impression of the mechanism of income distribution that gives us the chance to assess scale of inequality. To some extent it clarifies the wide-spread Gini coefficient and “the nature of populations’ wealth”.</p>