Modelling of Thin Films Hardness Measured by a Spherical Indenter

In this theoretical contribution, we chose to use an indenter having a spherical geometrical form, which we used to model the surfaces mixture to separate the contributions of substrate and film in the composite covered material hardness. We have considered the coefficients α, β of the model as ratios of the projections of the imprints at the horizontal plans (disks surfaces). We prove that the film hardness of monolayer coating is dependent on the composite and substrate hardness, the geometrical form of the indenter, and the film thickness.В этой теоретической работе рассмотрен индентор сферической геометрической формы, который был использован для составления модели смешанных поверхностей, чтобы оценить вклады подложки и плёнки в твёрдость композитного материала покрытия. Коэффициенты модели α, β рассматриваются как отношения проекций отпечатков на горизонтальные плоскости (в виде дисков). Доказано, что твёрдость плёнки однослойного покрытия зависит от твёрдостей композитного покрытия и подложки, геометрической формы индентора и толщины плёнки.У цій теоретичній роботі розглянуто індентор сферичної геометричної форми, який було використано для складання моделю змішаних поверхонь, щоб оцінити внески підкладинки та плівки у твердість композитного матеріялу покриття. Коефіцієнти моделю α, β розглядаються як співвідношення проєкцій відбитків на горизонтальні площини (у вигляді дисків). Доведено, що твердість плівки одношарового покриття залежить від твердостей композитного покриття та підкладинки, геометричної форми індентора та товщини плівки

Measured Hardness by an Indenter Having Ellipsoidal Shape

Если при исследовании твердости в качестве индентора использовалось твердое тело эллипсоидальной формы, выражение для статической твердости рассматривалось как функция от глубины и радиусов отпечатка индентора. При этом применялась общая формула, связывающая статическую твердость с отношением нормальной силы, прилагаемой к индентору, к реальной площади его отпечатка. При получении конечной формулы для расчета твердости использовались геометрический и математический подходы.Якщо при дослідженні твердості за індентор слугувало тверде тіло еліпсоїдної форми, вираз для статичної твердості розглядався як функція від глибини і радіусів відбитка індентора. При цьому використовувалась загальна формула, що зв язувала статичну твердість із відношенням нормальної сили, прикладеної до індентора, до реальної площі його відбитка. При отриманні кінцевої формули для розрахунку твердості використовувались геометричний і механічний підходи

Origins of the Ambient Solar Wind: Implications for Space Weather

The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind. We also discuss where the community stands in its ability to forecast how variations in the solar wind (i.e., fast and slow wind streams) impact the Earth. Although the last few decades have seen significant progress in observations and modeling, we still do not have a complete understanding of the relevant physical processes, nor do we have a quantitatively precise census of which coronal structures contribute to specific types of solar wind. Fast streams are known to be connected to the central regions of large coronal holes. Slow streams, however, appear to come from a wide range of sources, including streamers, pseudostreamers, coronal loops, active regions, and coronal hole boundaries. Complicating our understanding even more is the fact that processes such as turbulence, stream-stream interactions, and Coulomb collisions can make it difficult to unambiguously map a parcel measured at 1 AU back down to its coronal source. We also review recent progress -- in theoretical modeling, observational data analysis, and forecasting techniques that sit at the interface between data and theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue connected with a 2016 ISSI workshop on "The Scientific Foundations of Space Weather." 44 pages, 9 figure

Molecular and functional variation in iPSC-derived sensory neurons

Induced pluripotent stem cells (iPSCs), and cells derived from them, have become key tools for modeling biological processes, particularly in cell types that are difficult to obtain from living donors. Here we present a map of regulatory variants in iPSC-derived neurons, based on 123 differentiations of iPSCs to a sensory neuronal fate. Gene expression was more variable across cultures than in primary dorsal root ganglion, particularly for genes related to nervous system development. Using single-cell RNA-sequencing, we found that the number of neuronal versus contaminating cells was influenced by iPSC culture conditions before differentiation. Despite high differentiation-induced variability, our allele-specific method detected thousands of quantitative trait loci (QTLs) that influenced gene expression, chromatin accessibility, and RNA splicing. On the basis of these detected QTLs, we estimate that recall-by-genotype studies that use iPSC-derived cells will require cells from at least 20-80 individuals to detect the effects of regulatory variants with moderately large effect sizes

Pharmacological reversal of a pain phenotype in iPSC-derived sensory neurons and patients with inherited erythromelalgia

In common with other chronic pain conditions, there is an unmet clinical need in the treatment of inherited erythromelalgia (IEM). TheSCN9Agene encoding the sodium channel Nav1.7 expressed in the peripheral nervous system plays a critical role in IEM. A gain-of-function mutation in this sodium channel leads to aberrant sensory neuronal activity and extreme pain, particularly in response to heat. Five patients with IEM were treated with a new potent and selective compound that blocked the Nav1.7 sodium channel resulting in a decrease in heat-induced pain in most of the patients. We derived induced pluripotent stem cell (iPSC) lines from four of five subjects and produced sensory neurons that emulated the clinical phenotype of hyperexcitability and aberrant responses to heat stimuli. When we compared the severity of the clinical phenotype with the hyperexcitability of the iPSC-derived sensory neurons, we saw a trend toward a correlation for individual mutations. The in vitro IEM phenotype was sensitive to Nav1.7 blockers, including the clinical test agent. Given the importance of peripherally expressed sodium channels in many pain conditions, our approach may have broader utility for a wide range of pain and sensory conditions

Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg

© 2018, The Author(s). High-pressure torsion (HPT) processing was applied to cast pure magnesium, and the effects of the deformation on the microstructure, hardness, tensile properties and corrosion resistance were evaluated. The microstructures of the processed samples were examined by electron backscatter diffraction, and the mechanical properties were determined by Vickers hardness and tensile testing. The corrosion resistance was studied using electrochemical impedance spectroscopy in a 3.5% NaCl solution. The results show that HPT processing effectively refines the grain size of Mg from millimeters in the cast structure to a few micrometers after processing and also creates a basal texture on the surface. It was found that one or five turns of HPT produced no significant difference in the grain size of the processed Mg and the hardness was a maximum after one turn due to recovery in some grains. Measurements showed that the yield strength of the cast Mg increased by about seven times whereas the corrosion resistance was not significantly affected by the HPT processing

Distribution and variability of deformed wing virus of honeybees (Apis mellifera L.) in the Middle East and North Africa

Three hundred and eleven honeybee samples from 12 countries in the Middle East and North Africa (MENA) (Jordan, Lebanon, Syria, Iraq, Egypt, Libya, Tunisia, Algeria, Morocco, Yemen, Palestine, and Sudan) were analyzed for the presence of deformed wing virus (DWV). The prevalence of DWV throughout the MENA region was pervasive, but variable. The highest prevalence was found in Lebanon and Syria, with prevalence dropping in Palestine, Jordan, and Egypt before increasing slightly moving westwards to Algeria and Morocco Phylogenetic analysis of a 194 nucleotide section of the DWV Lp gene did not identify any significant phylogenetic resolution among the samples, although the sequences did show consistent regional clustering, including an interesting geographic gradient from Morocco through North Africa to Jordan and Syria. The sequences revealed several clear variability hotspots in the deduced amino acid sequence, which furthermore showed some patterns of regional identity. Furthermore, the sequence variants from the Middle East and North Africa appear more numerous and diverse than those from Europe