Etching of elemental layers in oxide molecular beam epitaxy by O2-assisted formation and evaporation of their volatile suboxide: The examples of Ga and Ge

The delivery of an elemental cation flux to the substrate surface in the oxide molecular beam epitaxy (MBE) chamber has been utilized not only for the epitaxial growth of oxide thin films in the presence of oxygen but also in the absence of oxygen for the growth temperature calibration (by determining the adsorption temperature of the elements) and in-situ etching of oxide layers (e. g., Ga2O3 etched by Ga). These elemental fluxes may, however, leave unwanted cation adsorbates or droplets on the surface, which traditionally require removal by in-situ superheating or ex-situ wet-chemical etching with potentially surface-degrading effects. This study demonstrates a universal in-situ approach to remove the residual cation elements from the surface via conversion into a volatile suboxide by a molecular O2-flux in an MBE system followed by suboxide evaporation at temperatures significantly below the elemental evaporation temperature. We experimentally investigate the in-situ etching of Ga and Ge cation layers and their etching efficiency using in-situ line-of-sight quadrupole mass spectrometry (QMS) and reflection high-energy electron diffraction (RHEED). The application of this process is demonstrated by the in-situ removal of residual Ga droplets from a SiO2 mask after structuring a Ga2O3 layer by in-situ Ga-etching. This approach can be generally applied in MBE and MOCVD to remove residual elements with vapor pressure lower than that of their suboxides, such as B, In, La, Si, Sn, Sb, Mo, Nb, Ru, Ta, V, and W

Temporal–spatial variability of grazing behaviors of yaks and the drivers of their intake on the eastern Qinghai-Tibetan Plateau

IntroductionGrassland-livestock balance is an important principle of sustainable development of grassland livestock production and grassland ecosystem health. Grassland degradation becomes more serious at global scales and especially at the area that is sensitive to climate change and human activities. Decreases in pasture biomass and shifts in plant community composition in degraded grasslands can largely affect grazing behaviors of livestock. Up to date, however, it is unclear that whether livestock behaviors change across spatial and temporal scales and what key factors are to shape observed behavioral patterns of livestock.MethodsHere, yak behaviors including grazing, rumination and walking on the eastern Qinghai-Tibetan Plateau (QTP) were monitored by a continuous visual observation, to investigate temporal and spatial variations of grazing behavior of yaks (Bos grunniens); based on the data from public database in the past 18 years, a meta-analysis was conducted to examine the main factors that affect grazing behaviors and intake of yaks.ResultsWe showed that grazing behaviors of yaks differed significantly within hours, among hours of each day and among days as well as across different observation sites. Intake rate of yaks was higher in the morning than in the afternoon, but walking speed showed an inverse trend compared with intake rate. Resting, altitude, the mean annual precipitation (MAP), the mean annual temperature (MAT), forage ash, yak age and season were the main predictors for yak intake, and forage and yak individual characteristics had direct effects on grazing behaviors and intake of yaks.DiscussionThe findings confirm that grazing behaviors of yaks can vary even at small temporal scales and regional scales, which is closely related to the shift in forage quality and biomass caused by environmental changes. The study suggests that multiple factors can be responsible for the variation in livestock behaviors and shifts in behavioral patterns may consequently lead to positive or negative feedback to grassland ecosystems through plant-animal interactions

Validation of a Disability Assessment Tool Based on the International Classification of Functioning, Disability, and Health in the Chinese Context

Background:The common standards of disability assessment for long-term care (LTC) insurance are currently absent. The International Classification of Functioning, Disability and Health (ICF) was designed for a better description of health and functioning, which could fill the demand gap for the standards of disability assessment and be a promising tool for the development of LTC insurance system.ObjectivesTo validate a disability assessment scale for disabled elderly individuals based on the ICF for LTC in the Chinese context.MethodsThe present study is a cross-sectional study. A disability assessment tool based on the ICF was developed by referring to other assessment tools and an expert consensus meeting in the initial phase of the study. The developed tool was used to evaluate 1,610 elderly individuals in the LTC institutions. The Cronbach's α coefficient and split-half reliability were applied to test the internal consistency of the tool, while the Interclass correlation coefficients (ICCs) were used to evaluate the interrater reliability (IRR). Factor analysis was performed to verify the construct validity of the tool. The scores from the Medical Outcomes Short Form-12 (SF-12) were correlated with that from the disability assessment tool, to assess the criterion-related validity.ResultsThe Cronbach's α coefficient and split-half reliability of the disability assessment tool were 0.969 and 0.877, respectively. The ICCs of the sum scale was 0.85, and the ICCs of each of the 20 items in the scale ranged from 0.78 to 0.94. The items were divided into three factors through analysis, which is consistent with the structure expectation. The scores of each item and the sum score of the disability assessment scale were negatively correlated with the scores of the physical and psychological fields in SF-12 (p < 0.001). Overall, the data indicated that the tool was characterized by good internal consistency, IRR, construct validity, and criterion-related validity.ConclusionsThe disability assessment tool based on the ICF is a reliable and valid tool for the collection of information on functioning across various LTC settings. The information of disability provided evidence for the distribution of LTC service and guided the development of LTC insurance standards

Characterizing microRNA editing and mutation sites in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder whose pathogenesis is still unclear. MicroRNAs (miRNAs) are a kind of endogenous small non-coding RNAs that play important roles in the post-transcriptional regulation of genes. Recent researches show that miRNAs are edited in multiple ways especially in central nervous systems. A-to-I editing of RNA catalyzed by Adenosine deaminases acting on RNA (ADARs) happens intensively in brain and is also noticed in other organs and tissues. Although miRNAs are widely edited in human brain, miRNA editing in ASD is still largely unexplored. In order to reveal the editing events of miRNAs in ASD, we analyzed 131 miRNA-seq samples from 8 different brain regions of ASD patients and normal controls. We identified 834 editing sites with significant editing levels, of which 70 sites showed significantly different editing levels in the superior frontal gyrus samples of ASD patients (ASD-SFG) when compared with those of control samples. The editing level of an A-to-I editing site in hsa-mir-376a-1 (hsa-mir-376a-1_9_A_g) in ASD-SFG is higher than that of normal controls, and the difference is exaggerated in individuals under 10 years. The increased expression of ADAR1 is consistent with the increased editing level of hsa-mir-376a-1_9_A_g in ASD-SFG samples compared to normal SFG samples. Furthermore, we verify that A-to-I edited hsa-mir-376a-5p directly represses GPR85 and NAPB, which may contribute to the abnormal neuronal development of ASD patients. These results provide new insights into the mechanism of ASD

From a barren rock to a “little dragon”: The evolution of Hong Kong society

Abstract not availabl