Shock vaporization/devolatilization of evaporitic minerals, halite and gypsum, in an open system investigated by a two-stage light gas gun

Dry lakebeds might constitute large volatile reservoirs on Mars. Hypervelocity impacts onto ancient dry lakebeds would have affected the volatile distribution on Mars. We developed a new experimental method to investigate the response of evaporitic minerals (halite and gypsum) to impact shocks in an open system. This technique does not result in chemical contamination from the operation of the gas gun. The technique is termed the two-valve method and the gun system is located in the Planetary Exploration Research Center, Chiba Institute of Technology, Japan. We detected the vaporization of halite at 31 GPa and devolatilization from gypsum at 11 GPa, suggesting that impact-induced volatile release from dry lakebeds has periodically occurred throughout Martian history. The vaporization of halite deposits might have enhanced the production of perchlorates, which are found globally on Mars. The water loss from gypsum possibly explains the coexisting types of Ca-sulfates found in Gale Crater.Comment: 17 pages, 4 figures, 1 supporting information, accepted for publication in Geophysical Research Letter

Inverse square Levy walk emerging universally in goal-oriented tasks

The Levy walk in which the frequency of occurrence of step lengths follows a power-law distribution, can be observed in the migratory behavior of organisms at various levels. Levy walks with power exponents close to 2 are observed, and the reasons are unclear. This study aims to propose a model that universally generates inverse square Levy walks (called Cauchy walks) and to identify the conditions under which Cauchy walks appear. We demonstrate that Cauchy walks emerge universally in goal-oriented tasks. We use the term "goal-oriented" when the goal is clear, but this can be achieved in different ways, which cannot be uniquely determined. We performed a simulation in which an agent observed the data generated from a probability distribution in a two-dimensional space and successively estimated the central coordinates of that probability distribution. The agent has a model of probability distribution as a hypothesis for data-generating distribution and can modify the model such that each time a data point is observed, thereby increasing the estimated probability of occurrence of the observed data. To achieve this, the center coordinates of the model must be moved closer to those of the observed data. However, in the case of a two-dimensional space, arbitrariness arises in the direction of correction of the center; this task is goal oriented. We analyze two cases: a strategy that allocates the amount of modification randomly in the x- and y-directions, and a strategy that determines allocation such that movement is minimized. The results reveal that when a random strategy is used, the Cauchy walk appears. When the minimum strategy is used, the Brownian walk appears. The presence or absence of the constraint of minimizing the amount of movement may be a factor that causes the difference between Brownian and Levy walks

Atomic-scale flattening of SiC surfaces by electroless chemical etching in HF solution with Pt catalyst

The authors present a method for flattening SiC surfaces with Pt as a catalyst in HF solution. The mechanism for flattening SiC surfaces is discussed. The flattened 4H-SiC (0001) surface is composed of alternating wide and narrow terraces with single-bilayer-height steps, which are induced by the rate difference of the catalytic reactions between adjacent terraces. Scanning tunneling microscopy images reveal a 1×1 phase on the terraces. The 1×1 phase is composed of coexisting of F- and OH-terminated Si atoms, which originate from the polarization of the underlying Si-C bonds. © 2007 American Institute of Physics.Kenta Arima, Hideyuki Hara, et al. "Atomic-scale flattening of SiC surfaces by electroless chemical etching in HF solution with Pt catalyst", Appl. Phys. Lett. 90(20), 202106 (2007) https://doi.org/10.1063/1.2739084

Microwave-assisted Tertiary Carbon Radical Reaction for Construction of Quaternary Carbon Center

Microwave-assisted tertiary carbon radical reaction was developed. The reaction of tertiary xanthates with electron deficient alkenes was prompted by microwave irradiation, and various coupling products possessing quaternary carbon centers were obtained in good yields. The reaction was conducted under simple and common radical condition except for microwave irradiation, and the reaction completes within 5 min

Crystalline Inclusions in Hepatocyte Mitochondria of a Patient with Porphyria Cutanea Tarda

Intramitochondrial crystalline inclusions were found in hepatocytes of a patient with porphyria cutanea tarda (PCT). They were composed of parallel filamentous structures which measured approximately 12 nm in diameter. Each filament was separated from an adjacent filament by a space measuring approximately 5 nm. The mitochondria containing such inclusions were usually elongated and enlarged. It seemed likely that these changes are not particular in PCT, but indicate one reversible pathological finding in the liver

The Relational Database for Research on Japanese Politics

本論文では,政治・行政データに関するリレーショナルデータベースの構築を目指した試みを紹介する.日本政治に関する多くの論文で統計分析が用いられる一方で,分析に用いるデータセットは，個々の研究者によってアドホックに作成されているのが現状である.この状況は,日本政治研究の発展を阻害するといっても過言ではなく,改普すべき点である.このような問題意識に立って,われわれは,さまざまな種類のデータを簡易な処理によって加工できるリレーショナルデータベースの構築を始めた.本論文が紹介するのは,その成果の一部である. このデータベースの特色は, ドラッグ&ドロップによる簡易な操作性, Excelなど表計算ソフトによっても可能な入力形式の柔軟性，データ内容を確認しながら処理できる視認性を重視した点である. また,映像編集ソフトのタイムラインから着想を得たインターフェースを採用することも特徴の一つである. 着手を始めたばかりの取り組みであるが,本データベースの開発は日本政治研究の発展に貢献を果たすものと考えられる.This paper presents our attempt to construct a relational database system designed for research on Japanese politics. Japanese political studies currently suffer from the insufficiency of data environment despite the growing uses of statistical analysis. As this can be a major factor hindering the development of research on Japanese politics，we began to construct a relational database system which utilizes an interface inspired by video editing software. The database system includes features that would facilitate data input and management in terms of convenience， visibility and flexibility. While there are still scopes for improvement，we believe that this system could contribute to the progress of the analysis of Japanese politics

Optimized protocol for the extraction of RNA and DNA from frozen whole blood sample stored in a single EDTA tube

Cryopreservation of whole blood is useful for DNA collection, and clinical and basic research. Blood samples in ethylenediaminetetraacetic acid disodium salt (EDTA) tubes stored at − 80 °C are suitable for DNA extraction, but not for high-quality RNA extraction. Herein, a new methodology for high-quality RNA extraction from human blood samples is described. Quickly thawing frozen whole blood on aluminum blocks at room temperature could minimize RNA degradation, and improve RNA yield and quality compared with thawing the samples in a 37 °C water bath. Furthermore, the use of the NucleoSpin RNA kit increased RNA yield by fivefold compared with the PAXgene Blood RNA Kit. Thawing blood samples on aluminum blocks significantly increased the DNA yield by ~ 20% compared with thawing in a 37 °C water bath or on ice. Moreover, by thawing on aluminum blocks and using the NucleoSpin RNA and QIAamp DNA Blood kits, the extraction of RNA and DNA of sufficient quality and quantity was achieved from frozen EDTA whole blood samples that were stored for up to 8.5 years. Thus, extracting RNA from frozen whole blood in EDTA tubes after long-term storage is feasible. These findings may help advance gene expression analysis, as well as biomarker research for various diseases

Neurocognitive Evaluation of Japanese Childhood Cancer Survivors

Long-term cognitive effects following acute lymphoblastic leukemia treatment have been reported for Caucasians; however, these data remain unclear for other ethnicities and the treatment of other cancers. Here, we assessed cognitive function in Japanese childhood cancer survivors. This study enrolled 53 Japanese survivors of childhood cancer （mean age, 9.5 years; 36 boys and 17 girls）. We evaluated performance-based cognitive function using the Wechsler Intelligence Scale for Children-Fourth Edition （WISC-Ⅳ）. Deviation intelligence quotients （IQ） for verbal comprehension （VC）, perceptual reasoning （PR）, processing speed （PS）, and working memory （WM） were compared with the standardized mean and standard deviation （SD; 100 and 15, respectively）. We classified patients into three groups depending on the cumulative methotrexate （MTX） dose （none, 1–19g/m2, and＞20g/m2）. Full-scale IQ was within normal range at 104.8 （SD, 12.9）, although there were significant differences among the four WISC–Ⅳ index scores （P＜0.001）. The PS score （97.1±15.5） was significantly lower than the VC （107.2±15.8） and PR （105.3±14.2） scores （both P＜0.005）. WM performance decreased in an MTX dose-dependent manner （107.8, 102.6, and 96.5 for none, 1–19g/m2, and higher than 20g/m2, respectively; P=0.05）. Japanese childhood cancer survivors, including those in the non-MTX group, demonstrated significant PS impairment. High-dose MTX treatment might be associated with neurocognitive deficiencies, particularly in WM. Although current treatments are associated with high cure rates, future research and interventions are required to improve cognitive function in these patients

Combinatorial screening of halide perovskite thin films and solar cells by mask-defined IR laser molecular beam epitaxy

As an extension of combinatorial molecular layer epitaxy via ablation of perovskite oxides by a pulsed excimer laser, we have developed a laser molecular beam epitaxy (MBE) system for parallel integration of nano-scaled thin films of organic–inorganic hybrid materials. A pulsed infrared (IR) semiconductor laser was adopted for thermal evaporation of organic halide (A-site:CH3NH3I) and inorganic halide (B-site: PbI2) powder targets to deposit repeated A/B bilayer films where the thickness of each layer was controlled on molecular layer scale by programming the evaporation IR laser pulse number, length, or power. The layer thickness was monitored with an in situ quartz crystal microbalance and calibrated against ex situ stylus profilometer easurements. A computer-controlled movable mask system enabled the deposition of combinatorial thin film libraries, where each library contains a vertically homogeneous film with spatially programmable A- and B-layer thicknesses. On the composition gradient film, a hole transport Spiro-OMeTADlayer was spin-coated and dried followed by the vacuum evaporation of Ag electrodes to form the solar cell. The preliminary cell performance was evaluated by measuring I-V characteristics at seven different positions on the 12.5 mm × 12.5 mm combinatorial library sample with seven 2 mm × 4 mm slits under a solar simulator irradiation. The combinatorial solar cell library clearly demonstrated that the energy conversion efficiency sharply changes from nearly zero to 10.2% as a function of the illumination area in the library. The exploration of deposition parameters for obtaining optimum performance could thus be greatly accelerated. Since the thickness ratio of PbI2 and CH3NH3I can be freely chosen along the shadow mask movement, these experiments show the potential of this system for high-throughput screening of optimum chemical composition in the binary film library and application to halide perovskite solar cell