Fabrication of CsPbBr₃ Thick Films by Using a Mist Deposition Method for Highly Sensitive X-ray Detection

X-ray imaging is a valuable technique used for medical imaging and non-destructive inspection of industrial products. However, the radiation may put humans at risk of developing cancer. Consequently, highly sensitive X-ray detectors, which enable X-ray imaging at a low dose rate, are required. Metal halide perovskite materials have demonstrated excellent X-ray detection performance including a high sensitivity owing to their high absorption coefficient, high carrier mobility, and long carrier lifetime. However, perovskite thick films with a large area, which is essential to realize the application of such materials to X-ray imaging devices have not been extensively investigated. To this end, in this study, a polymer is employed as a buffer layer to avoid film exfoliation, which makes it difficult to fabricate perovskite thick films, and a 110-μm-thick CsPbBr₃ film is successfully obtained using a scalable solution method. In addition, an X-ray detector based on the CsPbBr₃ thick film is fabricated, which demonstrates a sensitivity of 11, 840 μC Gyair⁻¹ cm⁻². This sensitivity is approximately 600 times higher than that of the existing commercial a-Se X-ray detectors

One-Step Coating of Full-Coverage CsPbBr₃ Thin Films via Mist Deposition for All-Inorganic Perovskite Solar Cells

In this work, one-step coating of CsPbBr₃ thin films using the mist deposition method is demonstrated. The CsPbBr₃ layer is composed of large grains with an average size of approximately 1.4 μm, and it fully covers the substrate surface, unlike the layers prepared by conventional one-step spin-coating methods, so that efficient carrier transport is realized. Carbon-based CsPbBr₃ perovskite solar cells (PSCs) fabricated using the mist deposition method exhibit a stabilized power conversion efficiency of 7.7%, which is a record value for carbon-based CsPbBr₃ PSCs prepared via a one-step solution process

Population and hierarchy of active species in gold iron oxide catalysts for carbon monoxide oxidation

The identity of active species in supported gold catalysts for low temperature carbon monoxide oxidation remains an unsettled debate. With large amounts of experimental evidence supporting theories of either gold nanoparticles or sub-nm gold species being active, it was recently proposed that a size-dependent activity hierarchy should exist. Here we study the diverging catalytic behaviours after heat treatment of Au/FeOx materials prepared via co-precipitation and deposition precipitation methods. After ruling out any support effects, the gold particle size distributions in different catalysts are quantitatively studied using aberration corrected scanning transmission electron microscopy (STEM). A counting protocol is developed to reveal the true particle size distribution from HAADF-STEM images, which reliably includes all the gold species present. Correlation of the populations of the various gold species present with catalysis results demonstrate that a size-dependent activity hierarchy must exist in the Au/FeOx catalyst

Monthly Precipitation Collected at Hirosaki, Japan: Its Tritium Concentration and Chemical and Stable Isotope Compositions

Monthly precipitation samples were collected at Hirosaki, Aomori Prefecture from January 2018 to December 2020 to measure the ion species and stable hydrogen and oxygen isotope ratios in order to understand the regional properties. The tritium concentration ranged from 0.28 to 1.20 Bq/L, with mean values (±S.D.) of 0.52 ± 0.18, 0.67 ± 0.25 and 0.63 ± 0.21 Bq/L in 2018, 2019 and 2020, respectively. This concentration level was almost the same as for Rokkasho, Aomori Prefecture. The tritium concentration had clear seasonal variation: high in the spring and low in the summer. This trend was thought to arise from seasonal fluctuations in the atmospheric circulation. On the other hand, the pH tended to be low, and the electrical conductivity (EC) tended to be high from the winter to the spring. The ion components, which major ion species contained in sea salt, also tended to be high in the winter, and these components had a strong influence on EC. The d-excess values were high in the winter and low in the summer, and when this trend was considered from the viewpoint of the wind direction data in Hirosaki, these dust components were attributed to the northwest monsoon in the winter to the spring coming from the Asian continent

PETREL for Astrophysics and Carbon Business

A multi-purpose 50kg class microsatellite hosting astrophysical mission and earth remote sensing, PETREL , will be launched in 2023. In the night side, PETREL observe the ultra-violet sky with a wide-field telescope covering 50 deg^2 for surveying transient objects related to supernovae, tidal disruption events, and gravitational wave events. Our UV telescope can detect the early phase UV emission from a neutron star merger occurred within 150 Mpc. In addition to the satellite observation, PETREL sends a detection alert including the coordinate and brightness of the UV transient to the ground via the real time communication network within several minutes after detection to conduct follow-up observations with the collaborating ground based observatories over the world. In the day side, PETREL observes the surface of the earth by using the tunable multi-spectral cameras and a ultra-compact hyperspectral camera. Our potential targets are the tropical forests (Green Carbon) and coastal zones (Blue Carbon) in the tropical areas to evaluating the global biological carbon strages. For this purpose PETREL will conduct multiple scale mapping collaborating with drones and small aircraft not only satellite. The obtained data will be used for academical research and for business applications. The technical difficulty of this satellite is that carries out multi-purpose with different requirements, such as astronomical observations which requires a quite high attitude stability and the earth observations requiring a high pointing accuracy, with limited resources. If it is possible, a novel small satellite system or a business style can be realized that can share the payload with academia and industry. PETREL has been adopted as Innovative Satellite Technology Demonstration Program No.3 led by JAXA, and development is underway with the aim of launching in FY2023

The whole blood transcriptional regulation landscape in 465 COVID-19 infected samples from Japan COVID-19 Task Force

「コロナ制圧タスクフォース」COVID-19患者由来の血液細胞における遺伝子発現の網羅的解析 --重症度に応じた遺伝子発現の変化には、ヒトゲノム配列の個人差が影響する--. 京都大学プレスリリース. 2022-08-23.Coronavirus disease 2019 (COVID-19) is a recently-emerged infectious disease that has caused millions of deaths, where comprehensive understanding of disease mechanisms is still unestablished. In particular, studies of gene expression dynamics and regulation landscape in COVID-19 infected individuals are limited. Here, we report on a thorough analysis of whole blood RNA-seq data from 465 genotyped samples from the Japan COVID-19 Task Force, including 359 severe and 106 non-severe COVID-19 cases. We discover 1169 putative causal expression quantitative trait loci (eQTLs) including 34 possible colocalizations with biobank fine-mapping results of hematopoietic traits in a Japanese population, 1549 putative causal splice QTLs (sQTLs; e.g. two independent sQTLs at TOR1AIP1), as well as biologically interpretable trans-eQTL examples (e.g., REST and STING1), all fine-mapped at single variant resolution. We perform differential gene expression analysis to elucidate 198 genes with increased expression in severe COVID-19 cases and enriched for innate immune-related functions. Finally, we evaluate the limited but non-zero effect of COVID-19 phenotype on eQTL discovery, and highlight the presence of COVID-19 severity-interaction eQTLs (ieQTLs; e.g., CLEC4C and MYBL2). Our study provides a comprehensive catalog of whole blood regulatory variants in Japanese, as well as a reference for transcriptional landscapes in response to COVID-19 infection

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target

ミストデポジション法による金属ハライドペロブスカイトの作製とその太陽電池およびX線検出器への応用

京都大学新制・課程博士博士(エネルギー科学)甲第24010号エネ博第446号新制||エネ||84(附属図書館)京都大学大学院エネルギー科学研究科エネルギー応用科学専攻(主査)教授 平藤 哲司, 教授 土井 俊哉, 教授 藤本 仁学位規則第4条第1項該当Doctor of Energy ScienceKyoto UniversityDFA

Fabrication of (101)-oriented CsPbBr₃ thick films with high carrier mobility using a mist deposition method

CsPbBr₃ is a promising candidate for highly sensitive flat-panel X-ray detectors due to its excellent optoelectronic properties. Thus, a method of preparing thick CsPbBr₃ films (>10 μm) over large areas (>10 × 10 cm²) is required. Herein, we report the fabrication of thick CsPbBr₃ films using a scalable mist deposition method. In this method, the film thickness was controlled and up-scaled by the number of deposition cycles. The obtained CsPbBr₃ films were composed of highly (101)-oriented columnar crystals and had a high carrier mobility of 13 cm² V⁻¹ s⁻¹, which is comparable to that for single crystals