638 research outputs found

    Magnetic properties of triethylene glycol coated CoFe2O4 and Mn0.2Co0.8Fe2O4 NP's synthesized by polyol method

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    AbstractIn this study, we reported on the structural and magnetic properties of TEG-CoFe2O4 and TEG-Mn0.2Co0.8Fe2O4 nanocomposites produced by the glycothermal reaction (polyol). X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibration sample magnetometer (VSM) analysis have been carried out in order to understand the effect of Mn2+ into CoFe2O4 and it was observed that the addition of Mn2+ tends to reduce the crystallite size, increase the ao (cell parameter) and increase the TB. The presence of adsorbed polyol entities on the surface of the CoFe2O4 and Mn0.2Co0.8Fe2O4 NP's was also proven by TG measurements. FT-IR analysis suggested the presence of adsorbed TEG molecules on the surface of CoFe2O4 and Mn0.2Co0.8Fe2O4 NP's

    A translational repression complex in developing mammalian neural stem cells that regulates neuronal specification

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    The mechanisms instructing genesis of neuronal sub-types from mammalian neural precursors are not well understood. To address this issue, we have characterized the transcriptional landscape of radial glial precursors (RPs) in the embryonic murine cortex. We show that individual RPs express mRNA, but not protein , for transcriptional specifiers of both deep and superficial layer cortical neurons. Some of these mRNAs, including the superficial versus deep layer neuron transcriptional regulators Brn1 and Tle4, are translationally repressed by their association with the RNA-binding protein Pumilio2 (Pum2) and the 4E-T protein. Disruption of these repressive complexes in RPs mid-neurogenesis by knocking down 4E-T or Pum2 causes aberrant co-expression of deep layer neuron specification proteins in newborn superficial layer neurons. Thus, cortical RPs are transcriptionally primed to generate diverse types of neurons, and a Pum2/4E-T complex represses translation of some of these neuronal identity mRNAs to ensure appropriate temporal specification of daughter neurons.No sponso

    Atmospheric transport and chemistry of trace gases in LMDz5B: evaluation and implications for inverse modelling

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    Representation of atmospheric transport is a major source of error in the estimation of greenhouse gas sources and sinks by inverse modelling. Here we assess the impact on trace gas mole fractions of the new physical parameterizations recently implemented in the atmospheric global climate model LMDz to improve vertical diffusion, mesoscale mixing by thermal plumes in the planetary boundary layer (PBL), and deep convection in the troposphere. At the same time, the horizontal and vertical resolution of the model used in the inverse system has been increased. The aim of this paper is to evaluate the impact of these developments on the representation of trace gas transport and chemistry, and to anticipate the implications for inversions of greenhouse gas emissions using such an updated model. Comparison of a one-dimensional version of LMDz with large eddy simulations shows that the thermal scheme simulates shallow convective tracer transport in the PBL over land very efficiently, and much better than previous versions of the model. This result is confirmed in three-dimensional simulations, by a much improved reproduction of the radon-222 diurnal cycle. However, the enhanced dynamics of tracer concentrations induces a stronger sensitivity of the new LMDz configuration to external meteorological forcings. At larger scales, the inter-hemispheric exchange is slightly slower when using the new version of the model, bringing them closer to observations. The increase in the vertical resolution (from 19 to 39 layers) significantly improves the representation of stratosphere/troposphere exchange. Furthermore, changes in atmospheric thermodynamic variables, such as temperature, due to changes in the PBL mixing modify chemical reaction rates, which perturb chemical equilibriums of reactive trace gases. One implication of LMDz model developments for future inversions of greenhouse gas emissions is the ability of the updated system to assimilate a larger amount of high-frequency data sampled at high-variability stations. Others implications are discussed at the end of the paper

    AREsite: a database for the comprehensive investigation of AU-rich elements

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    AREsite is an online resource for the detailed investigation of AU-rich elements (ARE) in vertebrate mRNA 3′-untranslated regions (UTRs). AREs are one of the most prominent cis-acting regulatory elements found in 3′-UTRs of mRNAs. Various ARE-binding proteins that possess RNA stabilizing or destabilizing functions are recruited by sequence-specific motifs. Recent findings suggest an essential role of the structural mRNA context in which these sequence motifs are embedded. AREsite is the first database that allows to quantify the structuredness of ARE motif sites in terms of opening energies and accessibility probabilities. Moreover, we also provide a detailed phylogenetic analysis of ARE motifs and incorporate information about experimentally validated targets of the ARE-binding proteins TTP, HuR and Auf1. The database is publicly available at: http://rna.tbi.univie.ac.at/AREsite

    DNA demethylases target promoter transposable elements to positively regulate stress responsive genes in Arabidopsis

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    © 2014 Le et al. Background: DNA demethylases regulate DNA methylation levels in eukaryotes. Arabidopsis encodes four DNA demethylases, DEMETER (DME), REPRESSOR OF SILENCING 1 (ROS1), DEMETER-LIKE 2 (DML2), and DML3. While DME is involved in maternal specific gene expression during seed development, the biological function of the remaining DNA demethylases remains unclear. Results: We show that ROS1, DML2, and DML3 play a role in fungal disease resistance in Arabidopsis. A triple DNA demethylase mutant, rdd (ros1 dml2 dml3), shows increased susceptibility to the fungal pathogen Fusarium oxysporum. We identify 348 genes differentially expressed in rdd relative to wild type, and a significant proportion of these genes are downregulated in rdd and have functions in stress response, suggesting that DNA demethylases maintain or positively regulate the expression of stress response genes required for F. oxysporum resistance. The rdd-downregulated stress response genes are enriched for short transposable element sequences in their promoters. Many of these transposable elements and their surrounding sequences show localized DNA methylation changes in rdd, and a general reduction in CHH methylation, suggesting that RNA-directed DNA methylation (RdDM), responsible for CHH methylation, may participate in DNA demethylase-mediated regulation of stress response genes. Many of the rdd-downregulated stress response genes are downregulated in the RdDM mutants nrpd1 and nrpe1, and the RdDM mutants nrpe1 and ago4 show enhanced susceptibility to F. oxysporum infection. Conclusions: Our results suggest that a primary function of DNA demethylases in plants is to regulate the expression of stress response genes by targeting promoter transposable element sequences

    Relationships among curricular and extra-curricular activities and fundamental competencies for working persons

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    Two kinds of data analysis methods were applied to the retrospective survey data collected by Morita, Shimizu, and Funaba (2012) to determine which university education programs and activities influence the alumni’s job performance. The result by correspondence analysis among university programs and activities and the fundamental competencies for working persons defined by the Japanese Ministry of Economy, Trade and Industry (2007) indicated the following four clusters: (1) seminar and one’s ability to deliver opinions clearly, to analyze the status quo, and to clarify issues; (2) curriculum and one’s foreign language ability; (3) extra-curricular activities and one’s ability to listen carefully to others’ opinions and to influence and involve others; and (4) one’s activities outside university and the ability to create new values. The causal relationships among the actual degrees of curricular and extra-curricular activities in university, the utility of such activities in university life, and the three factors extracted from the responses to the questions of the fundamental competencies were also analyzed by the path analysis method. Activities outside university affected most significantly the alumni’s ability to solve issues, while a few activitiesrelated to university life affected their ability to collaborate with various people and to manage stress. The methodological issues with the alumni survey were also discussed along with the implications of these findings.大学における教育プログラムと活動が,卒業生の仕事の遂行に与える影響について明らかにするために,森田・清水・船場(2011)によって収集された回想的調査データに2 種類の分析方法論を適用した。経済産業省(2007)によって定義された社会人基礎力と大学におけるプログラム,活動の関係についての対応分析による結果から,以下の4クラスタが得られた:⑴ゼミと自分の意見を分かりやすく伝える力,現状を分析し課題を明らかにする力,⑵講義と語学力,⑶正課外活動と相手の意見を丁寧に聴く力,他人に働きかけ巻き込む力,そして,⑷学外での活動と新しい価値を生み出す力,である。大学の正課・正課外活動,大学生活における幾つかの活動の有用性,そして基礎能力についての質問項目から抽出された3つの因子の因果関係について,パス解析による分析を行った。学外での活動は,課題解決力に対して最も有意に影響していた。大学生活における少数の活動が対人関係力,ストレス耐性力に影響していた。卒業生調査における方法論的問題とこれらの知見について考察を行った

    Magnetic properties of Fe implanted SrTiO3 perovskite crystal

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    The results of investigations of magnetic properties of SrTiO3 perovskite crystal implanted with 40 keV Fe ions at the fluencies between 0.5 × 1017 and 1.5 × 1017 ion/cm2 are presented. It has been revealed that high-fluency implantation with Fe ions results in the formation of a granular metal particulate composite in the irradiated near-surface layer of SrTiO3 substrate, which exhibits remarkable ferromagnetic behavior. The measurements of the temperature dependence of the magnetic moment showed that the samples exhibit blocking temperature at about 350 K, above which a superparamagnetic behavior has been observed. Ferromagnetic ordering and magnetic hysteresis loops were observed in Fe implanted SrTiO3 at the temperatures lower than 350 K. It has been shown that the magnetization of the ferromagnetic state depends on the fluency of implantation. © 2013 Elsevier Ltd. All rights reserved

    Plant-Expressed Cocaine Hydrolase Variants of Butyrylcholinesterase Exhibit Altered Allosteric Effects of Cholinesterase Activity and Increased Inhibitor Sensitivity

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    Butyrylcholinesterase (BChE) is an enzyme with broad substrate and ligand specificities and may function as a generalized bioscavenger by binding and/or hydrolyzing various xenobiotic agents and toxicants, many of which target the central and peripheral nervous systems. Variants of BChE were rationally designed to increase the enzyme’s ability to hydrolyze the psychoactive enantiomer of cocaine. These variants were cloned, and then expressed using the magnICON transient expression system in plants and their enzymatic properties were investigated. In particular, we explored the effects that these site-directed mutations have over the enzyme kinetics with various substrates of BChE. We further compared the affinity of various anticholinesterases including organophosphorous nerve agents and pesticides toward these BChE variants relative to the wild type enzyme. In addition to serving as a therapy for cocaine addiction-related diseases, enhanced bioscavenging against other harmful agents could add to the practicality and versatility of the plant-derived recombinant enzyme as a multivalent therapeutic

    Magnetic phase composition of strontium titanate implanted with iron ions

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    Thin magnetic films were synthesized by means of implantation of iron ions into single-crystalline (1 0 0) substrates of strontium titanate. Depth-selective conversion electron Mössbauer spectroscopy (DCEMS) indicates that origin of the samples magnetism is α-Fe nanoparticles. Iron-substituted strontium titanate was also identified but with paramagnetic behaviour at room temperature. Surface magneto-optical Kerr effect (SMOKE) confirms that the films reveal superparamagnetism (the low-fluence sample) or ferromagnetism (the high-fluence sample), and demonstrate absence of magnetic in-plane anisotropy. These findings highlight iron implanted strontium titanate as a promising candidate for composite multiferroic material and also for gas sensing applications. © 2011 Elsevier Ltd. All rights reserved
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