NFATc1/αA and Blimp-1 Support the Follicular and Effector Phenotype of Tregs

CD4+CXCR5+Foxp3+ T-follicular regulatory (TFR) cells control the germinal center responses. Like T-follicular helper cells, they express high levels of Nuclear Factor of Activated T-cells c1, predominantly its short isoform NFATc1/αA. Ablation of NFATc1 in Tregs prevents upregulation of CXCR5 and migration of TFR cells into B-cell follicles. By contrast, constitutive active NFATc1/αA defines the surface density of CXCR5, whose level determines how deep a TFR migrates into the GC and how effectively it controls antibody production. As one type of effector Treg, TFR cells express B lymphocyte-induced maturation protein-1 (Blimp-1). Blimp-1 can directly repress Cxcr5 and NFATc1/αA is necessary to overcome this Blimp-1-mediated repression. Interestingly, Blimp-1 even reinforces the recruitment of NFATc1 to Cxcr5 by protein-protein interaction and by those means cooperates with NFATc1 for Cxcr5 transactivation. On the contrary, Blimp-1 is necessary to counterbalance NFATc1/αA and preserve the Treg identity. This is because although NFATc1/αA strengthens the follicular development of Tregs, it bears the inherent risk of causing an ex-Treg phenotype.

Comparative modelling of the destruction of a soft armour barrier using two- and threedimensional textile materials based on orthogonal fabrics

The article suggests an approach to virtual testing of textile materials for high-speed penetration. The comparison of two materials developed using different technologies – 3D orthogonal fabric and a package of plain weave fabric is carried out. For this purpose, such parameters of fabrics are selected so that the surface density is identical, the number of layers is the same, the linear density of the threads would be the same. The material of the threads is aramid fibre. In general, according to the assessment along the warp and weft, the lesion area for 3D orthogonal tissue is higher by up to 30 %. At the same time, 31.7 % more kinetic energy of the bullet was extinguished.

FORMATION OF A NOVEL DIAMOND-LIKg BILAYER BASED ON 5-7 GRAPHENE

Выполнены первопринципные расчеты структуры и свойств орторомбического графена L и нового алмазоподобного бислоя, формируемого на его основе. Расчеты методом теории функционала плотности показали, что графен L, состоящий из топологических дефектов Стоуна-Уэльса, должен устойчиво существовать при нормальных условиях, и его структура должна волнообразно гофрироваться. При сильном одноосном сжатии бислойного графена L может происходить формирование нового алмазоподобного бислоя DL. Давление фазового перехода «L → DL» составляет 10,1 ГПа, когда межслоевое расстояние в бислойном графене уменьшается до 1,61 Å. Этот бислой имеет орторомбическую кристаллическую решетку (pbam) с параметрами a = 10,145 Å и b = 5,270 А. Элементарная ячейка бислоя DL pbam содержит 32 атома углерода. Длины связей изменяются в интервале от 1,5590 до 1,6226 Å, тогда как углы между связями принимают значения от 89,62 до 140,8°. Структура алмазоподобного бислоя должна быть стабильна до 270 К. Рассчитанные значения поверхностной плотности и разностной полной энергии этого бислоя относительно полной энергии алмаза равны 1,19·10 г/см и 1,31 эВ/атом, соответственно. Бислой DL pbam должен быть полупроводником с шириной прямой запрещенной зоны 1,63 эВ. Irst-principle calculations of the structure and properties of orthorhombic L graphene and a novel diamond-like bilayer formed on its basis are performed. The calculations using the density functional theory method showed that L- graphene of Stone-Wales defects should exist stably under normal conditions, and its structure should be corrugated in a wave-like manner. Under strong uniaxial compression of bilayer L graphene, the formation of the novel diamond-like DL bilayer can occur. The pressure of the « L → DL» phase transition is 10,1 GPa, when the interlayer distance in bilayer graphene decreases to 1,61 Å. This bilayer has an orthorhombic crystal lattice (pbam) with the parameters a = 10,145 Å and b = 5,270 Å. The unit cell of the DL- pbam bilayer contains 32 carbon atoms. The bond lengths vary in the range from 1,5590 to 1,6226 Å, while the angles between these bonds range from 89,62 to 140,8°. The structure of the diamond-like bilayer should be stable up to 270 K. The calculated values of the surface density and the difference total energy of this bilayer relative to the diamond total energy are 1,19 -10 g/cm and 1,31 eV/atom, respectively. The DL pbam bilayer should be a semiconductor with a straight bandgap of 1,63 eV.

Three-Dimensional Whole-Organ Characterization of the Regional Alveolar Morphology in Normal Murine Lungs

Alveolar architecture plays a fundamental role in the processes of ventilation and perfusion in the lung. Alterations in the alveolar surface area and alveolar cavity volume constitute the pathophysiological basis of chronic respiratory diseases such as pulmonary emphysema. Previous studies based on micro-computed tomography (micro-CT) of lung samples have allowed the geometrical study of acinar units. However, our current knowledge is based on the study of a few tissue samples in random locations of the lung that do not give an account of the spatial distributions of the alveolar architecture in the whole lung. In this work, we combine micro-CT imaging and computational geometry algorithms to study the regional distribution of key morphological parameters throughout the whole lung. To this end, 3D whole-lung images of Sprague–Dawley rats are acquired using high-resolution micro-CT imaging and analyzed to estimate porosity, alveolar surface density, and surface-to-volume ratio. We assess the effect of current gold-standard dehydration methods in the preparation of lung samples and propose a fixation protocol that includes the application of a methanol-PBS solution before dehydration. Our results show that regional porosity, alveolar surface density, and surface-to-volume ratio have a uniform distribution in normal lungs, which do not seem to be affected by gravitational effects. We further show that sample fixation based on ethanol baths for dehydration introduces shrinking and affects the acinar architecture in the subpleural regions. In contrast, preparations based on the proposed dehydration protocol effectively preserve the alveolar morphology.

Effect of the ultra-low arsenic flux on characteristics of In(As) nanostructures formed during droplet epitaxy

In this paper, we present the results of an experimental study of the influence of the ultra-low arsenic flux on the parameters of In nanodroplets obtained by droplet epitaxy on the GaAs substrate. We demonstrate that the arsenic flux can be used to alter the size of droplets without changing their surface density. An increase in the arsenic flux leads to a reduction of the nanostructure size or their complete decay. However, we demonstrate that certain growth conditions allow providing saturation of the size of nanostructures (∼30 nm) which ensures good reproducibility of the process. The mechanism of ring and hole formation at various arsenic fluxes is also discussed.

Magnetic Fields and Accreting Giant Planets around PDS 70

Recent high-spatial/spectral-resolution observations have enabled the formation mechanisms of giant planets to be constrained, especially at the final stages. The current interpretation of such observations is that these planets undergo magnetospheric accretion, suggesting the importance of planetary magnetic fields. We explore the properties of accreting, magnetized giant planets surrounded by their circumplanetary disks, using the physical parameters inferred for PDS 70 b/c. We compute the magnetic field strength and the resulting spin rate of giant planets and find that these planets may possess dipole magnetic fields of either a few 10 G or a few 100 G; the former is the natural outcome of planetary growth and radius evolution, while the resulting spin rate cannot reproduce the observations. For the latter, a consistent picture can be drawn, where strong magnetic fields induced by hot planetary interiors lead both to magnetospheric accretion and to spin-down due to disk locking. We also compute the properties of circumplanetary disks in the vicinity of these planets, taking into account planetary magnetic fields. The resulting surface density becomes very low, compared with the canonical models, implying the importance of radial movement of satellite-forming materials. Our model predicts a positive gradient of the surface density, which invokes traps for both satellite migration and radially drifting dust particles. This work thus concludes that the final formation stages of giant planets are similar to those of low-mass stars such as brown dwarfs, as suggested by recent studies.

A Lopsided Outer Solar System?

Axisymmetric disks of eccentric orbits in near-Keplerian potentials are unstable and undergo exponential growth in inclination. Recently, Zderic et al. showed that an idealized disk then saturates to a lopsided mode. Here we show, using N-body simulations, that this apsidal clustering also occurs in a primordial Scattered Disk in the outer solar system, which includes the orbit-averaged gravitational influence of the giant planets. We explain the dynamics using Lynden-Bell's mechanism for bar formation in galaxies. We also show surface density and line-of-sight velocity plots at different times during the instability, highlighting the formation of concentric circles and spiral arms in velocity space.