Generation of E × B flow shear by finite orbit width effects from heat sources in tokamaks

We present a possible mechanism for the generation of strong E × B flow shear relevant to internal transport barrier formation in tokamak plasmas. From gyrokinetic calculations, we show that strong E × B flow shear can be generated by finite orbit width (FOW) effects associated with a non-uniform heat source and is sufficient to lead to transport barrier formation in the core region with a moderate power level. Two FOW effects inducing neoclassical polarization are shown to be responsible for this: 1) the radial drift of particle orbit center due to the variation of the heat source within orbit width and 2) the non-uniformly evolved orbit width by the non-uniform heating.

Investigation of thin films for fabrication of Nb/AlN/NbN tunnel junctions and microstrip lines of NbTiN-SiO2-Al.

The surface of thin films of Nb, Al, NbTiN, SiO2, Al2O3 is investigated in this work. These films are necessary for the fabrication of high-sensitive devices of THz range. The fabrication processes of such devices are described briefly. All films were fabricated using a Kurt J. Lesker magnetron sputtering system. The study of the film surface roughness was carried out using a Bruker Ikon atomic force microscope. The surface quality of films is determined not only deposition mode, but plasma etching process also. The best values of the root-mean-square deviation of the surface profile Rq = 2 nm were obtained for the used NbTiN film with a thickness of 325 nm. Thin Al-layers that is used for tunnel barrier formation is studied. It is shown than Al films with a thickness of more than 6 nm are already continuous. The surface roughness of the single-layer and multilayer films has been studied.

Control and understanding of metal contacts to β-Ga2O3 single crystals: a review

Gallium oxide (Ga2O3) is a promising semiconductor for high power devices and solar blind ultraviolet photodetectors due to its large bandgap, a high breakdown field, and high thermal stability. Recently, a considerable achievement has been obtained for the growth of high-quality β-Ga2O3 and high performance β-Ga2O3 based devices. However, rapid advance in device performance can be limited by the critical issues of metal contacts to β-Ga2O3 such as barrier height, leakage current, ohmic contact, and surface, interfacial and deep states. This article aims to provide a review on the recent studies in the control and understanding of metal contacts to β-Ga2O3, particularly in terms of the barrier formation. This review suggests that understanding the current transport mechanisms of metal contacts to β-Ga2O3 more thoroughly is necessary to enhance the performance, stability and reliability of β-Ga2O3 based devices.

Spatiotemporal endometrial transcriptome analysis revealed the luminal epithelium as key player during initial maternal recognition of pregnancy in the mare

During the period of maternal recognition of pregnancy (MRP) in the mare, the embryo needs to signal its presence to the endometrium to prevent regression of the corpus luteum and prepare for establishment of pregnancy. This is achieved by mechanical stimuli and release of various signaling molecules by the equine embryo while migrating through the uterus. We hypothesized that embryo’s signals induce changes in the endometrial gene expression in a highly cell type-specific manner. A spatiotemporal transcriptomics approach was applied combining laser capture microdissection and low-input-RNA sequencing of luminal and glandular epithelium (LE, GE), and stroma of biopsy samples collected from days 10–13 of pregnancy and the estrous cycle. Two comparisons were performed, samples derived from pregnancies with conceptuses ≥ 8 mm in diameter (comparison 1) and conceptuses ≤ 8 mm (comparison 2) versus samples from cyclic controls. The majority of gene expression changes was identified in LE and much lower numbers of differentially expressed genes (DEGs) in GE and stroma. While 1253 DEGs were found for LE in comparison 1, only 248 were found in comparison 2. Data mining mainly focused on DEGs in LE and revealed regulation of genes related to prostaglandin transport, metabolism, and signaling, as well as transcription factor families that could be involved in MRP. In comparison to other mammalian species, differences in regulation of genes involved in epithelial barrier formation and conceptus attachment and implantation reflected the unique features of equine reproduction at the time of MRP at the molecular level.

Single Visit Apexification Using MTA: A Case Report

Trauma to the dentition during the period of root formation may cause incomplete development of root resulting in open apex. In order to eliminate infection from root canal endodontic treatment is a tooth-saving treatment modality. The absence of a natural apical constriction in a nonvital permanent tooth makes endodontic treatment a challenge. Therefore, it is necessary to induce or create an apical barrier against, which the obturating material can be condensed. Traditionally, calcium hydroxide is considered as the gold standard to induce apexification. Due to certain drawbacks such as very long treatment period, possibility of tooth fracture, and incomplete apical barrier formation, it is being replaced by materials, which have a more predictable outcome like mineral trioxide aggregate (MTA). One-step apexification with MTA reduces the treatment time when compared with traditional calcium hydroxide apexification, which requires an average time of 12–19 months. Also, MTA has various other superior properties compared to calcium hydroxide that are discussed below in detail along with successful treatment of an immature permanent tooth with open apex wherein MTA was used for one-step apexification.

Transverse barrier formation by electrical triggering of a metal-to-insulator transition

Application of an electric stimulus to a material with a metal-insulator transition can trigger a large resistance change. Resistive switching from an insulating into a metallic phase, which typically occurs by the formation of a conducting filament parallel to the current flow, is a highly active research topic. Using the magneto-optical Kerr imaging, we found that the opposite type of resistive switching, from a metal into an insulator, occurs in a reciprocal characteristic spatial pattern: the formation of an insulating barrier perpendicular to the driving current. This barrier formation leads to an unusual N-type negative differential resistance in the current-voltage characteristics. We further demonstrate that electrically inducing a transverse barrier enables a unique approach to voltage-controlled magnetism. By triggering the metal-to-insulator resistive switching in a magnetic material, local on/off control of ferromagnetism is achieved using a global voltage bias applied to the whole device.

Dysregulation of Grainyhead-like 3 expression causes widespread developmental defects

The gene encoding the transcription factor, Grainyhead-like 3 (Grhl3), plays critical roles in mammalian development and homeostasis, and these have been uncovered through analysis of loss-of-function models. Grhl3-null embryos exhibit a range of gross phenotypes including a shortened longitudinal axis, thoraco-lumbo-sacral spina bifida and soft-tissue syndactyly. Additional studies reveal that these embryos also exhibit a proliferation/differentiation imbalance in the epidermis. This manifests as a failure in skin barrier formation resulting in peri-natal lethality, and defective wound repair. Conditional inactivation of Grhl3 in the squamous epithelium of adult skin, head and neck tissues, and oesophagus reproduces this proliferation/differentiation imbalance and leads to squamous cell carcinomas. These observations establish GRHL3 as a critical tumour suppressor. Despite these extensive analyses of Grhl3 loss-of-function models, the consequences of gain-of-function of this gene have been difficult to achieve. We have redressed this issue through the generation of a novel mouse model that expresses Grhl3 from a transgene integrated in the Rosa26 locus on an endogenous Grhl3-null background. Expression of the transgene rescues both the neurulation and skin barrier defects of the knockout mice, allowing survival into adulthood. Despite this, the mice are not normal, exhibiting a range of phenotypes attributable to dysregulated Grhl3 expression. In mice homozygous for the transgene, we observe a severe Shaker-Waltzer phenotype associated with hearing impairment. Micro-CT scanning of the cochleae and the vestibular apparatus revealed profound structural alterations underlying these phenotypes. In addition, these mice exhibit other developmental anomalies including hair loss, digit defects and epidermal dysmorphogenesis. These findings indicate that diverse developmental processes display low tolerance to dysregulation of Grhl3.