Study of aging and electrochemical behaviour of Al?Li?Cu?Mg alloys

Aging study of 1441 and 8090 Al? Li? Cu? Mg alloys exhibited characteristic precipitation hardening phenomena. Potentiodynamic polarisation studies carried out on various tempers of the 1441 and 8090 Al? Li? Cu? Mg alloys in 3.5% NaCl, with a small amount of H₂O₂, and in 3.5% NaCl solution with pH 10 and 12 showed the shifting of open circuit potential (OCP) towards more negative potential and higher corrosion rate, with the increase of aging time. The OCP value has shifted anodically with addition of H₂O₂ in 3.5% NaCl solution. Further, passivity phenomenon has been observed for all the alloy tempers in 3.5% NaCl solution at pH 10 and 12. The observation of OCP shift towards more negative potential and the higher corrosion rate with the increase of aging time has been attributed to the presence of higher amounts of anodic δ (AlLi), S′ (Al₂CuMg) and T₁ (Al₂CuLi) phases, studied by TEM, XRD and DSC methods.     

Topical Developments in High-Field Dynamic Nuclear Polarization

We report our recent efforts directed at improving high-field dynamic nuclear polarization (DNP) experiments. We investigated a series of thiourea nitroxide radicals and the associated DNP enhancements ranging from ε=25 to 82, which demonstrate the impact of molecular structure on performance. We directly polarized low-gamma nuclei, including ¹³C, ²H, and ¹⁷O, by the cross effect mechanism using trityl radicals as a polarization agent. We discuss a variety of sample preparation techniques for DNP with emphasis on the benefits of methods that do not use a glass-forming cryoprotecting matrix. Lastly, we describe a corrugated waveguide for use in a 700 MHz/460 GHz DNP system that improves microwave delivery and increases enhancements up to 50 %.     

The “Monkey-Bar” Mechanism for Searching for the DNA Target Site: The Molecular Determinants

DNA recognition by DNA-binding proteins, which is a pivotal event in most gene regulatory processes, is often preceded by an extensive search for the correct site. A facilitated diffusion process, in which a DBP combines 3D diffusion in solution with 1D sliding along DNA, has been suggested to explain how proteins can locate their target sites on DNA much faster than predicted by 3D diffusion alone. One of the key mechanisms in the localization of the target by a DNA-binding protein is intersegment transfer in which the protein forms a bridged intermediate between two distant DNA regions. This jumping mechanism is more enhanced when the DNA-binding protein is asymmetric in its structure or its dynamics. We suggest that asymmetry supports the “monkey bar” mechanism, in which different domains of the protein interact with different DNA regions. In this minireview, we discuss how the molecular architectures of the proteins and DNA may modulate the efficiency of monkey bar dynamics.     

Preparation of SO42−/Fe2O3?MoO3 and its catalytic activity in the electrolytic reaction of phenol with methanol

BACKGROUND: Environmentally friendly solid catalysts are important in many processes from an industrial point of view and are applied widely in the study of alkylation of phenol with methanol in gas phase. However, liquid‐phase reactions have not been well studied. This paper deals with an assessment of liquid‐phase electrolytic alkylation in the presence of SO₄^2?/Fe₂O₃? MoO₃. RESULTS: A bidentate structure was formed between the SO₄^2? and metal. A catalyst with an amorphous structure delivered lower catalytic activity even at a higher Mo content. The highest activity was obtained at an Mo content of 16% (molar composition), which delivered a phenol conversion of up to 70.5%. Experiments also showed that the catalyst can be reused at least for three times. CONCLUSION: Application of solid catalyst in the liquid‐phase reaction assisted by electrolysis alkylation was found to be viable. The main products were methoxyphenols, in contrast to that associated with gas‐phase operation. A possible mechanism of product formation has been proposed. Copyright © 2008 Society of Chemical Industry     

Candidate Genes for Eyelid Myoclonia with Absences,Review of the Literature

Eyelid myoclonia with absences (EMA), also known as Jeavons syndrome (JS) is a childhood onset epileptic syndrome with manifestations involving a clinical triad of absence seizures with eyelid myoclonia (EM), photosensitivity (PS), and seizures or electroencephalogram (EEG) paroxysms induced by eye closure. Although a genetic contribution to this syndrome is likely and some genetic alterations have been defined in several cases, the genes responsible for have not been identified. In this review, patients diagnosed with EMA (or EMA-like phenotype) with a genetic diagnosis are summarized. Based on this, four genes could be associated to this syndrome (SYNGAP1, {"type":"entrez-protein","attrs":{"text":"KIA02022","term_id":"741799207"}}KIA02022/NEXMIF, RORB, and CHD2). Moreover, although there is not enough evidence yet to consider them as candidate for EMA, three more genes present also different alterations in some patients with clinical diagnosis of the disease (SLC2A1, NAA10, and KCNB1). Therefore, a possible relationship of these genes with the disease is discussed in this review.     

Ce∶LiM(M=Ca,Sr)A1F6晶体生长与性能研究

报道了在CF4 气氛中生长的掺Ce3 + 的LiM (M =Ca ,Sr)A1F6晶体和掺Ce3 + 的LiSr0 .8Ca0 .2 AlF6混晶 ,以及Ce3 + 在这些晶体中的紫外吸收光谱及有效分凝系数。Ce3 + ∶LiSr0 .8Ca0 .2 AlF6在 2 40～ 2 80nm波长范围内有连续展宽的吸收带 ,它的有效分凝系数为 0 0 37。Ce3 + 的吸收带展宽是由于Ce3 + 替代晶体中二价离子位引起的 ,表明Ce3 + 在Colquiriite结构的晶体中替代的是二价位     

近距离上位煤层开采底板破坏规律分析

针对近距离煤层群开采中存在开采中受多重动压影响,煤柱留设、巷道布置随意性强、缺少有效支护方式等问题,以己_16-17-23140运输巷为例,采用理论分析、数值模拟方法,研究了近距离上位煤层开采底板破坏规律,分析得出了侧向支承压力峰值随着与煤壁距离增大快速达到载荷峰值,得出侧向支承压力集度计算公式;计算得出平煤股份四矿己15煤层开采后的底板最大损伤破坏深度为30 m,利用FLAC^3D数值模拟软件模拟分析了上位煤层开采下伏煤岩体应力变化规律,随着垂直距离增加,支撑载荷集中系数慢慢减小。研究对矿井下分层全锚支护具有参考价值。     

Direct C‐2 Alkylation of Quinoline N‐Oxides with Ethers via Palladium‐Catalyzed Dehydrogenative Cross‐Coupling Reaction

An efficient and concise one‐pot strategy for the direct alkylation of quinoline N‐oxides via palladium‐catalyzed dual C H bonds activation has been developed. This methodology provides quinoline‐containing heterocyclic molecules in moderate to excellent yields.

     

Zheda‐Phos for General α‐Monoarylation of Acetone with Aryl Chlorides

A new, readily available, and air‐stable monophosphine ligand, i.e., Zheda‐Phos , has been developed for the general and highly effective palladium‐catalyzed monoarylation of acetone with aryl chlorides. The reaction rate is of first‐order dependence with the aryl chloride.     

Synthesis of 2‐Substituted Benzothiazoles by Visible Light‐Driven Photoredox Catalysis

An efficient method for synthesis of the widely applicable 2‐substituted benzothiazoles has been developed. The process requires only 0.1 mol% [Ru(bpy)₃Cl₂], O₂, and visible light irradiation with substrates: 2‐aminothiophenol and a variety of aldehydes. We established an oxidative quenching of the photoredox catalyst as being the key process in this photoelectrocatalytic cycle.