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41.
Nanometer-sized grain structures that exhibit a large number of grain boundaries on the surface of a bulk material demonstrate excellent properties relative to their coarse-grained (CG) equivalents. Surface modification using surface mechanical attrition treatment (SMAT) is an option that cab be used to tailor the corrosion, tribological, mechanical, and chemical reaction properties of a surface. SMAT is an effective route to create the nanostructured surface layer. The SMAT process has unique advantages compared with the other coating and deposition techniques for surface nanocrystallization. For example, SMAT does not alter the chemical composition of the nanocrystalline surface layer in the matrix. In addition, SMAT has been demonstrated to activate the material surface layer by surface modification and enhance the atomic diffusivity. This article presents a review of the advantages offered by the SMAT technique for the creation of high performance surface layers. The influence of the created nanocrystalline layer on mechanical, physical, and chemical properties is assessed. Developments and the current status of the surface nanolayer that are formed are evaluated from a physical approach. Finally, prospects for the future development of grain refinement on the surface of a material matrix and potential applications are presented.  相似文献   
42.
The building blocks of life, amino acids, are believed to have been synthesized in the extreme conditions that prevail in space, starting from simple molecules containing hydrogen, carbon, oxygen and nitrogen. However, the fate and role of amino acids when they are subjected to similar processes largely remain unexplored. Here we report, for the first time, that shock processed amino acids tend to form complex agglomerate structures. Such structures are formed on timescales of about 2 ms due to impact induced shock heating and subsequent cooling. This discovery suggests that the building blocks of life could have self-assembled not just on Earth but on other planetary bodies as a result of impact events. Our study also provides further experimental evidence for the ‘threads’ observed in meteorites being due to assemblages of (bio)molecules arising from impact-induced shocks.  相似文献   
43.
An efficient method for the preparation of novel 2-(5-arylisoxazol-3-yl)cyclohexa-2,5-diene-1,4-dione hybrids via 1,3-dipolar cycloaddition followed by an oxidation reaction using ceric ammonium nitrate (CAN) has been described. Using this method, various aryl as well as alkyl substituted isoxazole-benzoquinone hybrids were synthesized in high yields.  相似文献   
44.
The stability of regioregular poly(3-hexylthiophene 2,5-diyl) (P3HT) thin films sandwiched between indium tin oxide (ITO) and aluminium (Al) electrodes have been investigated under normal environmental conditions (25°C and RH∼45–50%). Electrical and optical properties of ITO/P3HT/Al devices have been studied over a period of 30 days. Mobility μ of the order of 10−4 cm2/V-s has been obtained from the V 2 law in the as-deposited P3HT films. Scanning electron microscopy (SEM) investigations show blistering of Al contacts in devices with a poly(3,4-ethylenedioxythiophene) (PEDOT) interlayer on application of voltage whereas no blistering is seen in devices without PEDOT. The results have been explained in terms of trap generation and propagation and the moisture-absorbing nature of PEDOT.   相似文献   
45.
A highly sensitive, rapid assay method has been developed and validated for the simultaneous estimation of tolmetin (TMT) and MED5 in human plasma with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive‐ion mode. A simple solid‐phase extraction process was used to extract TMT and MED5 along with mycophenolic acid (internal standard, IS) from human plasma. Chromatographic separation was achieved with 0.2% formic acid–acetonitrile (25:75, v/v) at a flow rate of 0.50 mL/min on an X‐Terra RP18 column with a total run time of 2.5 min. The MS/MS ion transitions monitored were 258.1 → 119.0 for TMT, 315.1 → 119.0 for MED5 and 321.2 → 207.0 for IS. Method validation and clinical sample analysis were performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 20 ng/mL and the linearity was observed from 20 to 2000 ng/mL, for both the anlaytes. The intra‐day and inter‐day precisions were in the range 3.27–4.50 and 5.32–8.18%, respectively for TMT and 4.27–5.68 and 5.32–8.85%, respectively for MED5. This novel method has been applied to a clinical pharmacokinetic study. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
46.
We show that polarisations of type on -dimensional abelian varieties are never very ample, if . This disproves a conjecture of Debarre, Hulek and Spandaw. We also give a criterion for non-embeddings of abelian varieties into -dimensional linear systems.

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47.
Novel sulfuric acid-functionalized mesoporous benzene-silicas with a molecular-scale periodicity in the walls were derived from the mesoporous benzene-silica possessing mercaptopropyl groups by the oxidative transformation of -SH into -SO3H.  相似文献   
48.
49.
The complexes [(η5-C5H5)M(CO)nPbPh3] (M = Fe, Cr, Mo, W) have been studied with respect to their thermal and photochemical stability and their reactivity with respect to SO2. The iron complex is the only complex that exhibits the ability to decompose via a 1,2-phenyl migration to the transition metal under thermal conditions, but photochemically the tungsten complex also exhibits this behaviour. All complexes react readily with SO2 to yield the corresponding sulphinatophenyl complexes, LMSO2Ph, in high yield.  相似文献   
50.
The trivalent ruthenium, rhodium and iridium complexes of dipicolinic acid and its mixed ligand complexes with several nitrogen, oxygen donor molecules, of types: Na[M(dipic)2]·2H2O and [M(dipic)(N-O)]·nH2O (where M = Ru(III), Rh(III) or Ir(III); dipicH2 = dipicolinic acid; NOH represents different nitrogen, oxygen donor molecules, viz., picolinic acid, nicotinic acid, isonicotinic acid, glycine, aminophenol, o- or p-aminobenzoic acid), have been synthesized and characterised on the basis of elemental analyses, electrical conductance, magnetic susceptibility measurements and spectral (electronic and infrared) data. The parent dipicolinic acid complexes are found to have a six-coordinate pseudooctahedral structure, whereas for mixed ligand complexes, a polymeric six-coordinate structure has been assigned. Various ligand field and nephelauxetic parameters have also been evaluated.  相似文献   
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