Изучение свойств нитрид-, карбидкремниевого (Si[3]N[4]-SiC) композиционного материала

Materials based on silicon carbide and nitride occupy a certain segment of ceramics market due to its thermal and chemical stability, thermal conductivity and hardness. In presented report properties, composition, structure and catalytic activity of silicon nitride and silicon carbide Si[3]N[4]-SiC material have been studied. The behavior of 5% mas. Ag supported on Si[3]N[4]-SiC has been investigated in the process of gas-phase catalytic oxidation of ethylene glycol to glyoxal

本邦で分離されたカルバペネマーゼ産生肺炎桿菌の分子遺伝学的解析

Carbapenemase-producing Enterobacteriaceae represent a serious public health threat worldwide. Carbapenemase genes, harbored on a transferable plasmid, have been isolated globally with distinct geographical features. Klebsiella pneumoniae, included in Enterobacteriaceae, also produces carbapenemase and often shows hypervirulence. Overlapping carbapenem resistance and hypervirulence in K. pneumoniae have been reported, but such strains have not yet been found in Japan. Here, we screened 104 carbapenemase-producing K. pneumoniae isolates collected from 37 hospitals and outpatient clinics in Japan between September 2014 and July 2015. PCR and DNA sequencing demonstrated IMP-1 in 21 isolates and IMP-6 in 83 isolates, 77 of which coharbored CTX-M-2. Most of the isolates showed low MICs toward imipenem and meropenem but high MICs toward penicillin and cephalosporins. Conjugation experiments with an Escherichia coli J53 recipient showed that most of the plasmids in IMP-6 producers were transferable, whereas only one-half of the plasmids in IMP-1 producers were transferable. PCR-based replicon typing and multiplex PCR identified five isolates belonging to the CG258 non-tonB79 cluster and no isolate belonging to the CG258-tonB79 cluster or sequence type 307 (ST307). Four K1-ST23 isolates, 10 K2-ST65 isolates, and 7 K2-ST86 isolates were detected that harbored virulence genes. The resistance genes in 85 isolates were transferable, but the virulence genes were not transferred. These results demonstrate the acquisition of IMP-type carbapenemase genes and CTX-M-type genes among hypervirulence isolates in Japan, warranting further attention and countermeasures. In this study, we have determined the molecular characteristics and epidemiology of IMP-6 producers that coharbored various CTX-M genes in Japan.IMPORTANCE Carbapenems serve as a last resort for the clinical treatment of multidrug-resistant infections. Therefore, the rapid spread of carbapenemase-producing strains represents a serious public health threat, further limiting antibiotic choices. The current findings of hypervirulent carbapenemase-producing Klebsiella pneumoniae clinical isolates in Japan demonstrate the potential broad spread and transfer of these genes, necessitating close surveillance.博士（医学）・乙第1509号・令和3年3月15日Copyright © 2020 Yonekawa et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license(https://creativecommons.org/licenses/by/4.0/)

Control of Cortical Axon Elongation by a GABA-Driven Ca<sup style="margin: 0px; padding: 0px; border: 0px; outline-style: none; font-weight: inherit; font-style: inherit; font-size: 0.85em; font-family: inherit; line-height: 0; text-align: inherit; vertical-align: super;">2+/Calmodulin-Dependent Protein Kinase Cascade</sup>

Ca(2+) signaling plays important roles during both axonal and dendritic growth. Yet, whether and how Ca(2+) rises may trigger and contribute to the development of long range cortical connections remains largely unknown. Here we demonstrate that two separate limbs of CaMK kinase (CaMKK) - CaMKI cascades, CaMKK-CaMKIα and CaMKK-CaMKIγ, critically coordinate axonal and dendritic morphogenesis of cortical neurons, respectively. The axon-specific morphological phenotype required a diffuse cytoplasmic localization and a strikingly α-isoform-specific kinase activity of CaMKI. Unexpectedly, treatment with muscimol, a GABA(A) receptor agonist, selectively stimulated elongation of axons but not of dendrites, and the CaMKK-CaMKIα cascade critically mediated this axonogenic effect. Consistent with these findings, during early brain development, in vivo knockdown of CaMKIα significantly impaired the terminal axonal extension, and thereby perturbed the refinement of the interhemispheric callosal projections into the contralateral cortices. Our findings thus indicate a novel role for the GABA-driven CaMKK-CaMKIα cascade as a mechanism critical for accurate cortical axon pathfinding, an essential process which may contribute to fine-tuning the formation of interhemispheric connectivity during the perinatal development of the central nervous system

The Constrained Maximal Expression Level Owing to Haploidy Shapes Gene Content on the Mammalian X Chromosome.

X chromosomes are unusual in many regards, not least of which is their nonrandom gene content. The causes of this bias are commonly discussed in the context of sexual antagonism and the avoidance of activity in the male germline. Here, we examine the notion that, at least in some taxa, functionally biased gene content may more profoundly be shaped by limits imposed on gene expression owing to haploid expression of the X chromosome. Notably, if the X, as in primates, is transcribed at rates comparable to the ancestral rate (per promoter) prior to the X chromosome formation, then the X is not a tolerable environment for genes with very high maximal net levels of expression, owing to transcriptional traffic jams. We test this hypothesis using The Encyclopedia of DNA Elements (ENCODE) and data from the Functional Annotation of the Mammalian Genome (FANTOM5) project. As predicted, the maximal expression of human X-linked genes is much lower than that of genes on autosomes: on average, maximal expression is three times lower on the X chromosome than on autosomes. Similarly, autosome-to-X retroposition events are associated with lower maximal expression of retrogenes on the X than seen for X-to-autosome retrogenes on autosomes. Also as expected, X-linked genes have a lesser degree of increase in gene expression than autosomal ones (compared to the human/Chimpanzee common ancestor) if highly expressed, but not if lowly expressed. The traffic jam model also explains the known lower breadth of expression for genes on the X (and the Z of birds), as genes with broad expression are, on average, those with high maximal expression. As then further predicted, highly expressed tissue-specific genes are also rare on the X and broadly expressed genes on the X tend to be lowly expressed, both indicating that the trend is shaped by the maximal expression level not the breadth of expression per se. Importantly, a limit to the maximal expression level explains biased tissue of expression profiles of X-linked genes. Tissues whose tissue-specific genes are very highly expressed (e.g., secretory tissues, tissues abundant in structural proteins) are also tissues in which gene expression is relatively rare on the X chromosome. These trends cannot be fully accounted for in terms of alternative models of biased expression. In conclusion, the notion that it is hard for genes on the Therian X to be highly expressed, owing to transcriptional traffic jams, provides a simple yet robustly supported rationale of many peculiar features of X's gene content, gene expression, and evolution

Highly Selective Sorption and Separation of CO₂ from a Gas Mixture of CO₂ and CH₄ at Room Temperature by a Zeolitic Organic–Inorganic Ionic Crystal and Investigation of the Interaction with CO₂

Mixed gas cosorption and gas chromatographic investigations demonstrate that a zeolitic organic–inorganic ionic crystal K₂[Cr₃O­(OOCH)₆(4-etpy)₃]₂[α-SiW₁₂O₄₀]·2H₂O [<b>1</b>·2H₂O] (etpy = ethylpyridine) with a pore diameter of 3.5 Å possesses high separation ability of carbon dioxide (kinetic diameter 3.3 Å) over methane (3.76 Å) at room temperature in the presence of water vapor. Monte Carlo simulation combined with density functional theory calculation suggests that carbon dioxide molecules diffuse into the one-dimensional channels and interact initially with the potassium ions and then with the oxygen atoms of silicododecatungstates, which are confirmed with carbon dioxide sorption enthalpy and <i>in situ</i> IR spectroscopy

Redox-Induced Reversible Uptake–Release of Cations in Porous Ionic Crystals Based on Polyoxometalate: Cooperative Migration of Electrons with Alkali Metal Ions

Redox-active porous ionic crystals based on polyoxometalates (POM) were synthesized. By treating the crystal with an aqueous solution of ascorbic acid (reducing reagent) and KCl, one-electron reduction of POM proceeded followed by simultaneous uptake of K⁺. Interestingly, the reduction did not proceed without KCl, and the molecular size of ascorbic acid was too large to enter the porous crystal lattice. The time courses of reduction and K⁺ uptake were monitored by UV–vis spectroscopy and atomic absorption spectrometry (AAS), respectively. Both profiles could be reproduced by the linear driving force (LDF) model with similar rate constants. The reduced crystal could be oxidized with aqueous chlorine solution followed by the release of K⁺, and the redox cycles were reversible. The water sorption properties of the crystals could be controlled by the types of alkali metal ions incorporated. The Cs⁺ uptake and the simultaneous reduction of the crystal proceeded much faster than in the case of K⁺, which is in line with the trends in the Gibbs energies of hydration of alkali metal ions. Complete selectivity to Cs⁺ was observed in the uptake of ions from an aqueous binary mixture of Cs⁺ and Na⁺. All these results suggest the cooperative migration of electrons with alkali metal ions and the redox induced ion-exchange in porous ionic crystals based on POM

Control of Polymorphisms and Functions in All-Inorganic Ionic Crystals Based on Polyaluminum Hydroxide and Polyoxometalates

Two kinds of polymorphs of all-inorganic ionic crystals were obtained by the combination of oppositely charged molecular ions (macroions) with <i>T</i>_d symmetry, Keggin-type polyaluminum hydroxide [ε-Al₁₃O₄(OH)₂₄(H₂O)₁₂]⁷⁺ (<b>Al</b>_<b>13</b>) and polyoxometalates (POMs) [α-CoW₁₂O₄₀]^6– (<b>POM6</b>), [α-1,2,3-SiV^V₃W₉O₄₀]^7– (<b>POM7</b>), or [α-1,2,3-SiV^IVV^V₂W₉O₄₀]^8– (<b>POM8</b>) in aqueous solutions. The needle-type crystals were grown by dissolution-recrystallization of the precipitates, which formed immediately by combining <b>Al</b>_<b>13</b> and POMs. On the other hand, the plate-type crystals were grown by adding inorganic salts (e.g., NaCl) into the aqueous solution containing the needle-type crystals: Dissolution of the needle-type crystals occurred followed by precipitation of the plate-type crystals, which is the more insoluble and stable polymorph with larger numbers of hydrogen bonds between the constituent ions. The plate-type crystals possess one-dimensional channels with large apertures (ca. 12 Å × 6 Å) and showed high activities as heterogeneous solid acid catalysts in pinacol rearrangement

Concerted Functions of Anions and Cations in a Molecular Ionic Crystal with Stable Three-Dimensional Micropores

The molecular ionic crystal [Cr₃O­(OOCCHCH₂)₆(H₂O)₃]₃[α-PW₁₂O₄₀]·15H₂O [<b>Ia</b>] with stable three-dimensional micropores and a minimum aperture of 3.3 Å was synthesized with a phosphododecatungstate [α-PW₁₂O₄₀]^3– (polyoxometalate, POM) and a macrocation with acrylate ligands [Cr₃O­(OOCCHCH₂)₆­(H₂O)₃]⁺. The porous structure of <b>Ia</b> was basically constructed by an arrangement of macrocations forming a six-membered ring: vinyl groups (CHCH₂) of adjacent macrocations were aligned parallel to each other, suggesting a weak dispersion force between them. A guest-free phase [Cr₃O­(OOCCHCH₂)₆­(H₂O)₃]₃­[α-PW₁₂O₄₀] [<b>Ib</b>] was formed by the treatment of <b>Ia</b> in vacuo at room temperature without any structure change. Compound <b>Ib</b> showed shape-selective sorption of CO₂ and C₂H₂ (molecular size = 3.3 Å) over N₂ (3.6 Å) and methane (3.7 Å), and the sorption enthalpy of C₂H₂ was larger than that of CO₂. The high affinity toward C₂H₂ was further confirmed as follows: the Monte Carlo simulations of the optimized geometries of C₂H₂ in <b>Ib</b> showed that both hydrogen atoms were in the vicinity of the surface oxygen atoms of POMs. The gas sorption profiles showed a much faster diffusion for C₂H₂. All these results suggest that the anion and cation mainly play the guest-binding and structure-directing roles, respectively, (i.e., concerted functions) in an ionic crystal with stable three-dimensional micropores