Borohydrides

硼氢化物
  • 文章类型: Journal Article
    RNA中表位基因组修饰的功能分析受到缺乏准确捕获其位置和水平的方法的限制。我们先前证明,RNA修饰N4-乙酰胞苷(ac4C)可以通过硼氢化钠还原为四氢乙酰胞苷(四氢-ac4C)以碱基分辨率定位,随后进行cDNA合成,使腺苷错误掺入相对于减少的ac4C位点,在乙酰化的胞苷(RedaC:T)处达到C:T错配。然而,这个过程相对低效,在18SrRNA中的完全修饰的ac4C位点处导致小于20%的C:T错配。考虑到包括mRNA在内的其他底物中的ac4C位置不太可能达到完全外显率,这种方法对于全面映射并不理想。这里,我们引入了“RetraC:T”(还原为四氢ac4C并用氨基dATP进行逆转录以诱导C:T错配)作为一种增强检测细胞RNA中ac4C的能力的方法。简而言之,RNA通过NaBH4或密切相关的试剂氰基硼氢化钠(NaCNBH3)还原,然后在修饰的DNA核苷酸存在下进行cDNA合成,2-氨基-dATP,优先结合四氢-ac4C。引入改良的dNTP大大提高了C:T失配率,在18SrRNA中达到ac4C的化学计量检测。重要的是,2-氨基-dATP不会导致截短的cDNA产物,也不会增加其他位置的错配。因此,修改后的dNTP作为新添加到工具箱中,用于以基本分辨率检测ac4C。
    The functional analysis of epitranscriptomic modifications in RNA is constrained by a lack of methods that accurately capture their locations and levels. We previously demonstrated that the RNA modification N4-acetylcytidine (ac4C) can be mapped at base resolution through sodium borohydride reduction to tetrahydroacetylcytidine (tetrahydro-ac4C), followed by cDNA synthesis to misincorporate adenosine opposite reduced ac4C sites, culminating in C:T mismatches at acetylated cytidines (RedaC:T). However, this process is relatively inefficient, resulting in <20% C:T mismatches at a fully modified ac4C site in 18S rRNA. Considering that ac4C locations in other substrates including mRNA are unlikely to reach full penetrance, this method is not ideal for comprehensive mapping. Here, we introduce \"RetraC:T\" (reduction to tetrahydro-ac4C and reverse transcription with amino-dATP to induce C:T mismatches) as a method with enhanced ability to detect ac4C in cellular RNA. In brief, RNA is reduced through NaBH4 or the closely related reagent sodium cyanoborohydride (NaCNBH3) followed by cDNA synthesis in the presence of a modified DNA nucleotide, 2-amino-dATP, that preferentially binds to tetrahydro-ac4C. Incorporation of the modified dNTP substantially improved C:T mismatch rates, reaching stoichiometric detection of ac4C in 18S rRNA. Importantly, 2-amino-dATP did not result in truncated cDNA products nor increase mismatches at other locations. Thus, modified dNTPs are introduced as a new addition to the toolbox for detecting ac4C at base resolution.
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  • 文章类型: Journal Article
    在弱配位非质子环境中通过离子复分解反应合成了四甲基硼氢化物。[(CH3)4P]BH4,与倾向于在四方晶系中结晶的相关[(CH3)4N]化合物相反,采用扭曲的纤锌矿结构(P63mc),类似于一些含有类似As和Sb离子的盐。[(CH3)4P]BH4在上述几个吸热和放热步骤中热分解。240°C。这使得它比[(CH3)4N]BH4更稳定,分解起始温度降低了约1。20°C和单独观察到的放热过程。在0-10GPa范围内测得的拉曼光谱表明,在0.53-1.86GPa内发生了多态转变,这由周期性DFT计算进一步证实。后者表明约0.8GPa的相变为[(CH3)4N]BH4的高压相。P63mc相似乎在高压下由于相对更紧密的二氢相互作用而不稳定,包括C-H...H-C触点.
    Tetramethylphosphonium borohydride was synthesized via an ion metathesis reaction in a weakly-coordinating aprotic environment. [(CH3)4P]BH4, in contrast to related [(CH3)4N]+ compounds which tend to crystallize in a tetragonal system, adopts the distorted wurtzite structure (P63mc), resembling some salts containing analogous ions of As and Sb. [(CH3)4P]BH4 decomposes thermally in several endo- and exothermic steps above ca. 240 °C. This renders it more stable than [(CH3)4N]BH4, with a lowered temperature of decomposition onset by ca. 20 °C and solely exothermic processes observed. Raman spectra measured at the 0-10 GPa range indicate that a polymorphic transition occurs within 0.53-1.86 GPa, which is further confirmed by the periodic DFT calculations. The latter suggests a phase transition around 0.8 GPa to a high-pressure phase of [(CH3)4N]BH4. The P63mc phase seems to be destabilized under high pressure by relatively closer dihydrogen interactions, including the C-H…H-C contacts.
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  • 文章类型: Journal Article
    石榴石型氧化物Li6.4La3Zr1.4Ta0.6O12(LLZTO)具有优异的离子导电性和对锂(Li)金属的良好稳定性,但是需要高温烧结(约1200°C),这会导致高制造成本,机械加工性差,和高界面电阻。这里,报道了一种包含LLZTO-4LiBH4/xLi3BN2H8的新型高性能三组分复合固体电解质(CSE),它是通过球磨LLZTO-4LiBH4混合物,然后用Li3BN2H8手工研磨制备的。通过在120°C下加热冷压CSE粉末制成的绿色颗粒可提供超快的室温离子电导率(在30°C下约为1.73×10-3Scm-1)和超高的锂离子迁移数(约0.9999),这使得Li|Li对称电池在30°C下以仅30mV的过电位循环超过1600h。此外,Li|CSE|TiS2全电池提供201mAhg-1的容量,具有长循环能力。这些出色的性能是由于电解质颗粒中的低开孔率以及Li3BN2H8的高固有离子电导率和易变形性。
    Garnet-type oxide Li6.4 La3 Zr1.4 Ta0.6 O12 (LLZTO) features superior ionic conductivity and good stability toward lithium (Li) metal, but requires high-temperature sintering (≈1200 °C) that induces high fabrication cost, poor mechanical processability, and high interface resistance. Here, a novel high-performance tricomponent composite solid electrolyte (CSE) comprising LLZTO-4LiBH4 /xLi3 BN2 H8 is reported, which is prepared by ball milling the LLZTO-4LiBH4  mixture followed by hand milling with Li3 BN2 H8 . Green pellets fabricated by heating the cold-pressed CSE powders at 120 °C offer ultrafast room-temperature ionic conductivity (≈1.73 × 10-3  S cm-1  at 30 °C) and ultrahigh Li-ion transference number (≈0.9999), which enable the Li|Li symmetrical cells to cycle over 1600 h at 30 °C with only 30 mV of overpotential. Moreover, the Li|CSE|TiS2  full cells deliver 201 mAh g-1  of capacity with long cyclability. These outstanding performances are due to the low open porosity in the electrolyte pellets as well as the high intrinsic ionic conductivity and easy deformability of Li3 BN2 H8 .
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  • 文章类型: Journal Article
    通过三种不同途径合成的AgNP的比较评估。丁香芽提取物介导的AgNPs,硼氢化钠AgNPs和谷胱甘肽(GSH)覆盖的AgNPs用于抗氧化和杀蚊子的活性是本研究的主要重点。使用紫外-可见分光光度法对纳米粒子进行表征,动态光散射(DLS),X射线衍射(XRD)场发射扫描电子显微镜(FE-SEM),透射电子显微镜(TEM)和傅里叶变换红外光谱(FTIR)分析。表征研究揭示了稳定的合成,晶体AgNPs测量28nm,7nm和36nm为绿色,化学和GSH封端的AgNPs。FTIR分析显示出负责还原的表面官能部分,加帽和稳定AgNPs。抗氧化活性为74.11%,丁香为46.62%和58.78%,分别为硼氢化物和GSH封端的AgNP。AgNPs对埃及伊蚊的杀幼虫生物活性显示丁香AgNPs最有效(LC50-4.9ppm,LC90-30.2ppm),然后是GSH封端(LC50-20.13ppm,LC90-46.63ppm)和硼氢化物AgNPs(LC50-13.43ppm,LC90-160.19ppm)24小时后。对水生模型大型水蚤的毒性筛选显示,与硼氢化物AgNP相比,丁香介导的和GSH封端的AgNP更安全。可以设想,绿色和封端的AgNP可以被进一步探索用于多种生物医学和治疗应用。
    A comparative assessment of AgNPs synthesized through three different routes viz. clove bud extract mediated AgNPs, sodium borohydride AgNPs and Glutathione (GSH) capped AgNPs for antioxidant and mosquito larvicidal activities was the major focus of the present study. The nanoparticles were characterized using UV-VIS spectrophotometry, dynamic light scattering (DLS), X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. Characterization studies revealed the synthesis of stable, crystalline AgNPs measuring 28 nm, 7 nm and 36 nm for green, chemical and GSH-capped AgNPs respectively. FTIR analysis exhibited the surface functional moieties that were responsible for reduction, capping and stabilizing AgNPs. Antioxidant activity was found to be 74.11%, 46.62% and 58.78% for clove, borohydride and GSH-capped AgNPs respectively. Mosquito larvicidal bioactivity of AgNPs against Aedes aegypti IIIrd instar larvae depicted clove AgNPs being most effective (LC50-4.9 ppm, LC90-30.2 ppm) followed by GSH-capped (LC50-20.13 ppm, LC90-46.63 ppm) and borohydride AgNPs (LC50-13.43 ppm, LC90-160.19 ppm) after 24 h. Toxicity screening against aquatic model Daphnia magna revealed Clove mediated and GSH-capped AgNPs to be safer as compared to the borohydride AgNPs. It may be envisaged that green and capped AgNPs may be further explored for diverse biomedical and therapeutic applications.
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  • 文章类型: Journal Article
    合成中使用的稀土(RE)起始材料的数量惊人,从简单的二元金属卤化物盐到硼氢化物和“设计试剂”,如烷基和有机铝酸盐络合物。这篇综述整理了RE合成化学中使用的最重要的起始材料,包括有关其制备和在现代合成方法中使用的基本信息。审查按起始材料类别和支持配体(即,金属作为合成前体,卤化物,硼氢化物,氮供体,氧气供体,三氟甲烷,和有机金属试剂),并在每一节中讨论了相关的合成方法和应用。
    The number of rare earth (RE) starting materials used in synthesis is staggering, ranging from simple binary metal-halide salts to borohydrides and \"designer reagents\" such as alkyl and organoaluminate complexes. This review collates the most important starting materials used in RE synthetic chemistry, including essential information on their preparations and uses in modern synthetic methodologies. The review is divided by starting material category and supporting ligands (i.e., metals as synthetic precursors, halides, borohydrides, nitrogen donors, oxygen donors, triflates, and organometallic reagents), and in each section relevant synthetic methodologies and applications are discussed.
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  • 文章类型: Journal Article
    使用生物活性化合物制备的银纳米颗粒(AgNP)的杀生物性质似乎对于生物和医学应用尤其重要。因此,这项研究的目的是确定和比较15种AgNP的抗菌和杀真菌特性。主要假设是AgNPs的生物活性具有相当的大小分布,形状,和离子释放曲线取决于吸附在其表面上的稳定剂分子的性质。选择大肠杆菌和金黄色葡萄球菌作为两种细菌细胞的模型。选择白色念珠菌作为真核微生物的代表性类型进行研究。所进行的研究表明,较大的AgNP可以比较小的AgNP更具杀生能力。发现带正电荷的精氨酸稳定的AgNP(ARGSBAgNP)是所有研究的纳米颗粒中最具生物杀灭性的。对于使用(-)-表没食子儿茶素没食子酸酯(EGCG)获得的带负电荷的EGCGAgNP,检测到最强的杀真菌特性。结论是,通过使用特定的稳定剂,可以调节AgNP对所需病原体的毒性的选择性。已经确定,无论AgNP大小和表面性质如何,大肠杆菌对AgNP暴露比金黄色葡萄球菌更敏感。
    The biocidal properties of silver nanoparticles (AgNPs) prepared with the use of biologically active compounds seem to be especially significant for biological and medical application. Therefore, the aim of this research was to determine and compare the antibacterial and fungicidal properties of fifteen types of AgNPs. The main hypothesis was that the biological activity of AgNPs characterized by comparable size distributions, shapes, and ion release profiles is dependent on the properties of stabilizing agent molecules adsorbed on their surfaces. Escherichia coli and Staphylococcus aureus were selected as models of two types of bacterial cells. Candida albicans was selected for the research as a representative type of eukaryotic microorganism. The conducted studies reveal that larger AgNPs can be more biocidal than smaller ones. It was found that positively charged arginine-stabilized AgNPs (ARGSBAgNPs) were the most biocidal among all studied nanoparticles. The strongest fungicidal properties were detected for negatively charged EGCGAgNPs obtained using (-)-epigallocatechin gallate (EGCG). It was concluded that, by applying a specific stabilizing agent, one can tune the selectivity of AgNP toxicity towards desired pathogens. It was established that E. coli was more sensitive to AgNP exposure than S. aureus regardless of AgNP size and surface properties.
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  • 文章类型: Journal Article
    Silver nanomaterials have attracted a great deal of interest due to their broad-spectrum antimicrobial activity. However, it is still challenging to balance the high antibacterial efficiency with low damage to biological cells of silver nanostructures, especially when the diameter decreases to less than 10 nm. Here, we developed a new type of Ag nanohybrid material via a unimolecular micelle template method, which presents amazing antibacterial activities and almost noncytotoxicity. First, water-soluble multiarm star-shaped brushlike copolymer α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 was precisely synthesized and its micelle behavior in different solvents was revealed. Then, nanocrystal clusters assembled by Ag grains (Ag@Template NCs) were prepared through an in situ redox route using the unimolecular micelle of α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 as the soft template, AgNO3 as a precursor, and tetrabutylammonium borohydride (TBAB) as the reducing agent. The overall size of the achieved Ag@Template NCs is controlled by the template structure at around 40 nm (Dh in DMF), and the size of the Ag grain can be easily regulated from ∼1 to ∼5 nm by adjusting the feeding ratio of AgNO3/acrylic acid (AA) units in the template from 1:10 to 1:1. Benefitting from the structural design of the template, all Ag@Template NCs prepared here exhibit excellent dispersibility and chemical stability in different aqueous environments (neutral, pH = 5.5, and 0.9% NaCl physiological saline solution), which play a crucial role in the long-term storage and potential application in a complex physiological environment. The antibacterial and cytotoxicity tests indicate that Ag@Template NCs display much better performance than Ag nanoparticles (Ag NPs), which have a comparable overall size of ∼25 nm. The inhibitory capability of Ag@Template NCs to bacteria strongly depends on the grain size. Specifically, the Ag@Template-1 NC assembled by the smallest grains (1.6 ± 0.3 nm) presents the best antibacterial activity. For E. coli (-), the MIC value is as low as 5 μg/mL (0.36 μg/mL of Ag), while for S. aureus (+), the value is around 10 μg/mL (0.72 μg/mL of Ag). The survival rate of L02 cells and lactate dehydrogenase assay together illustrate the low cytotoxicity possessed by the prepared Ag@Template NCs. Therefore, the proposed Ag@Template NC structure successfully resolves the high reactivity, instability, and fast oxidation issues of the ultrasmall Ag nanoparticles, and integrates high antibacterial efficiency and nontoxicity to biological cells into one platform, which implies its broad potential application in biomedicine.
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  • 文章类型: Journal Article
    溶解有机物(DOM)与硼氢化钠的反应已用于了解DOM的地理起源并研究DOM光学性质的光物理模型。然而,DOM的物理化学性质(例如,分子大小和电荷)通过硼氢化物影响DOM的动力学和最终还原性的特征仍然很差。在这里,我们研究了DOM-硼氢化物反应的动力学,通过记录高时间频率的吸光度和荧光光谱(每10分钟,24小时)为一组不同的水生和土壤来源的DOM分离物。在所研究的DOM样品中,硼氢化钠对DOM的还原性(通过初始吸光度的相对去除来判断)差异很大,土壤腐殖质的还原性低于水生腐殖质和天然有机质。虽然DOM的可还原性与分子大小的描述符之间存在统计学上的显着相关性,这些描述符无法区分具有相似整体特性的土壤和水生DOM分离物的还原性。因此,看来,硼氢化物去除吸光度的程度在很大程度上是由腐殖质分离物(水生与土壤)的起源而不是分子大小或电荷驱动的。硼氢化物还原导致跨UV和可见激发波长的荧光发射增加。然而,在可见光激发下增强的发射在数小时到数天的时间内减少,表明DOM发色团的重要子集的减少是可逆的。荧光发射的这种可逆性与醌在DOM吸光度中的小作用一致,但表明在DOM的荧光中含醌的电荷转移接触具有更重要的作用,特别是在可见光激发波长。
    The reaction of dissolved organic matter (DOM) with sodium borohydride has been used to understand the geographic origin of DOM and investigate the photophysical model underlying DOM\'s optical properties. However, the physicochemical properties of DOM (e.g., molecular size and charge) that influence the kinetics and ultimate reducibility of DOM by borohydride remain poorly characterized. Herein, we studied the kinetics of DOM-borohydride reactions by recording absorbance and fluorescence spectra at a high temporal frequency (every ∼10 min for 24 h) for a diverse set of DOM isolates of aquatic and soil origin. The reducibility of DOM by sodium borohydride (as judged by relative removal of initial absorbance) varied appreciably among the DOM samples studied, with soil humic substances being less reducible than aquatic humic substances and natural organic matter. While statistically significant correlations were found between the reducibility of DOM and descriptors of molecular size, these descriptors were not able to differentiate the reducibility of soil versus aquatic DOM isolates that had similar bulk properties. Thus, it appears that the extent of absorbance removal by borohydride is largely driven by the origin of the humic substance isolate (aquatic vs soil) instead of molecular size or charge. Borohydride reduction resulted in increased fluorescence emission across UV and visible excitation wavelengths. However, the enhanced emission at visible excitation decreased over a time period of hours to days, suggesting that reduction of an important subset of DOM chromophores is reversible. This reversibility in fluorescence emission is consistent with the small role of quinones in the absorbance of DOM but suggests a more important role for quinone-containing charge-transfer contacts in the fluorescence of DOM, particularly at visible excitation wavelengths.
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  • 文章类型: Journal Article
    作为一种环保、高密度的能源载体,氢已被公认为化石燃料的理想替代品之一。“氢经济”面临的主要挑战之一是发展高效、低成本,从化学储存材料中安全和选择性地产生氢气。在这次审查中,我们总结了轻金属基材料水解和醇解制氢的最新进展,如硼氢化物,镁基和铝基材料,以及硼氢化物的高效再生。不幸的是,这些可水解材料中的大多数仍然受到缓慢的动力学和低氢产率的困扰。虽然包括催化在内的许多策略,合金化,解决方案修改,和球磨已经被开发来克服这些缺点,水解/醇解系统的“单程”利用所需的高成本最终使这些技术几乎不可能用于实际的大规模应用。因此,必须开发基于丰富资源和有效回收乏燃料技术的低成本材料系统,以实现高效运输,在基于燃料电池的氢经济中生产和储存氢。
    As an environmentally friendly and high-density energy carrier, hydrogen has been recognized as one of the ideal alternatives for fossil fuels. One of the major challenges faced by \"hydrogen economy\" is the development of efficient, low-cost, safe and selective hydrogen generation from chemical storage materials. In this review, we summarize the recent advances in hydrogen production via hydrolysis and alcoholysis of light-metal-based materials, such as borohydrides, Mg-based and Al-based materials, and the highly efficient regeneration of borohydrides. Unfortunately, most of these hydrolysable materials are still plagued by sluggish kinetics and low hydrogen yield. While a number of strategies including catalysis, alloying, solution modification, and ball milling have been developed to overcome these drawbacks, the high costs required for the \"one-pass\" utilization of hydrolysis/alcoholysis systems have ultimately made these techniques almost impossible for practical large-scale applications. Therefore, it is imperative to develop low-cost material systems based on abundant resources and effective recycling technologies of spent fuels for efficient transport, production and storage of hydrogen in a fuel cell-based hydrogen economy.
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  • 文章类型: Journal Article
    这篇综述包括合成方法的汇编以及I组和II组以外的硼氢化物的几种性质,即,过渡金属,主要群体,镧系元素,和act系元素。报告的性质包括晶体结构,分解温度,离子电导率,光致发光,等。,可用时。编制的性质反映了丰富的化学性质和可能的硼氢化物在储氢等领域的应用,需要离子导体的电子设备,催化作用,或光致发光。在审查结束时,包括两个简短但必不可少的部分:所有报告的硼氢化物的分解温度与阳离子的鲍林电负性的汇编,并简要讨论了乙硼烷排放过程中可能发生的反应,包括一些减少这种不便的策略,特别是用于储氢的目的。
    This review consists of a compilation of synthesis methods and several properties of borohydrides beyond Groups I and II, i.e., transition metals, main group, lanthanides, and actinides. The reported properties include crystal structure, decomposition temperature, ionic conductivity, photoluminescence, etc., when available. The compiled properties reflect the rich chemistry and possible borohydrides\' application in areas such as hydrogen storage, electronic devices that require an ionic conductor, catalysis, or photoluminescence. At the end of the review, two short but essential sections are included: a compilation of the decomposition temperature of all reported borohydrides versus the Pauling electronegativity of the cations, and a brief discussion of the possible reactions occurring during diborane emission, including some strategies to reduce this inconvenience, particularly for hydrogen storage purposes.
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