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Selected AbstractsTransition of Failure Mode and Enhanced Plastic Deformation of Metallic Glass by Multiaxial Confinement,ADVANCED ENGINEERING MATERIALS, Issue 11 2009Fu-Fa Wu Multiple shear bands are formed in a confined metallic-glass specimen under small-punch loading. The intersecting of shear bands and the formation of profuse secondary shear bands are promoted under this confinement; accordingly, the failure mode changes from catastrophic fracture to stable multiple shear banding. Multiaxial confinement is an effective method to stabilize shear banding and further enhance the mechanical performance, especially the plastic deformation capability of metallic glass. These results present a simple step for making shear banding more stable and exploiting the shear-deformation capability of metallic glasses, leading to the toughening of brittle metallic glasses and potentially broadening their applications. [source] Enhanced Electrical Switching and Electrochromic Properties of Poly(p-phenylenebenzobisthiazole) Thin Films Embedded with Nano-WO3ADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Jiahua Zhu Abstract The electrical switching and electrochromic phenomena of a novel nanocomposite comprising poly(p-phenylenebenzobisthiazole) (PBZT) and tungsten oxide (WO3) nanoparticles are investigated as a function of the nanoparticle loading. Both dissolving PBZT and doping PBZT backbone structure with acid are achieved by one simple step. Chlorosulfonic acid (CSA) is used as a solvent and spontaneously transformed to sulfuric acid upon exposure to moisture. The formed sulfuric acid serves as doping agent to improve the electrical conductivity of PBZT. The most significant enhancement of electrical switching is observed in the nanocomposites with low weight fraction (5%). The electrical conductivity of 5% WO3/PBZT nanocomposite thin film is increased by about 200 times and 2 times, respectively, as compared to those of the as-received PBZT and PBZT/CSA thin films. As the nanoparticle loading increases to 20% and 30%, the nanocomposites follow an ohmic conduction mechanism. Stable electrical conductivity switching is observed before and after applying a bias on the pristine PBZT and WO3/PBZT nanocomposite thin films. Electrochromic phenomena of both PBZT and WO3/PBZT nanocomposite thin films with high contrast ratio are observed after applying a bias (3 V). The mechanisms of the nanoparticles in enhancing the electrical switching and electrochromic properties are proposed. [source] Self-Organization of a Highly Integrated Silicon Nanowire Network on a Si(110),16,×,2 Surface by Controlling Domain GrowthADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Ie-Hong Hong Abstract Here, bottom-up nanofabrication for the two-dimensional self-organization of a highly integrated, well-defined silicon nanowire (SiNW) mesh on a naturally-patterned Si(110),16,×,2 surface by controlling the lateral growths of two non-orthogonal 16,×,2 domains is reported. This self-ordered nanomesh consists of two crossed arrays of parallel-aligned SiNWs with nearly identical widths of 1.8,2.5,nm and pitches of 5.0,5.9,nm, and is formed over a mesoscopic area of 300,×,270,nm2 so as to show a high integration density in excess of 104,µm,2. These crossed SiNWs exhibit semiconducting character with an equal band gap of ,0.95,eV as well as unique quantum confinement effect. Such an ultrahigh-density SiNW network can serve as a versatile nanotemplate for nanofabrication and nanointegration of the highly-integrated metal-silicide or molecular crossbar nanomesh on Si(110) surface for a broad range of device applications. Also, the multi-layer, vertically-stacked SiNW networks can be self-assembled through hierarchical growth, which opens the possibility for creating three-dimensionally interconnected crossbar circuits. The ability to self-organize an ultrahigh-density, functional SiNW network on a Si(110) surface represents a simple step toward the fabrication of highly-integrated crossbar nanocircuits in a very straightforward, fast, cost-effective, and high throughput process. [source] Rapid analysis of food products by means of high speed gas chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2007Paola Donato Abstract Since the invention of GC, there has been an ever increasing interest within the chromatographic community for faster GC methods. This is obviously related to the fact that the number of samples subjected to GC analysis has risen greatly. Nowadays, in routine analytical applications, sample throughput is often the most important aspect considered when choosing an analytical method. Gas chromatographic instrumentation, especially in the last decade, has been subjected to continuous and considerable improvement. High-speed injection systems, electronic gas pressure control, rapid oven heating/cooling and fast detection are currently available in a variety of commercial gas chromatographs. The main consequence of this favourable aspect is that high-speed GC is being increasingly employed for routine analysis in different fields. Furthermore, the employment of dedicated software makes the passage from a conventional to a fast GC method a rather simple step. The present review provides an overview of the employment of fast GC techniques for the analysis of food constituents and contaminants. A brief historical and theoretical background is also provided for the approaches described. [source] Liberalisation of legal services in Europe: progress and prospectsLEGAL STUDIES, Issue 2 2010Robert G Lee The usual excuse for regulation is the failure of market provision. This paper examines legal services and suggests that, in the case of provision of commercial legal services to corporate clients, true events of market failure, to support the case for regulation, and more particularly self-regulation, are hard to locate. It further argues that the market for legal services is heavily stratified with a commercial legal services market effectively operating quite separately to that of professional legal services for private clients. In consequence, it may be more effective and proportionate to adopt differentiated strategies of regulation. This might be achieved by shifting the focus of regulation away from the individual practitioner, as is historically the case, towards law firms as such. This simple step, it is suggested, could facilitate much greater liberalisation of the market for legal services. This proposal is explored with particular reference to freedom of services within the European single market and, as a backdrop to the paper, progress to date in facilitating cross-border legal services in Europe is reviewed. [source] A mass spectrometric strategy for profiling glycoproteinoses, Pompe disease, and sialic acid storage diseasesPROTEOMICS - CLINICAL APPLICATIONS, Issue 4 2008Valegh Faid Abstract Glycoproteinoses, Pompe disease, and sialic acid storage diseases are characterized by a massive accumulation of unprocessed oligosaccharides and/or glycoconjugates in urine. The identification of these glycocompounds is essential for a proper diagnosis. In this study, we investigated the potential of MALDI-TOF-MS to identify glycocompounds present in urine from patients with different inborn errors of glycan metabolism. Urinary glycocompounds were permethylated, and analyzed using GC-MS and MALDI-TOF-MS. In order to confirm tentative assignments, a second aliquot of urine was purified on a C18 Sep-Pak cartridge and glycocompounds were desalted on a column of nonporous graphitized carbon. The glycocompounds were then sequentially on-plate digested using an array of exoglycosidases. A range of disease-specific oligosaccharides as well as glycopeptides was identified for all oligosacchariduria models. In addition, free sialic acid accumulated in urine from a patient suffering from French-type sialuria, has been detected by a GC-MS approach, which could be applied to other sialic acid storage diseases. This procedure is simple, and can be performed in few simple steps in less than 24,h. This current method can be applied for newborn screening for other inherited metabolic diseases as well as for assessing treatments in clinical trials. [source] Olefins as Steering Ligands for Homogeneously Catalyzed HydrogenationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2004Pascal Maire Abstract Iridium(I) complexes containing a (5H -dibenzo[a,d]cyclohepten-5-yl)-phosphane (troppR; R = phosphorus-bound substituent = Ph, Cyc) as a rigid, concave-shaped, mixed phosphane olefin ligand were prepared and tested as catalyst precursors in the hydrogenation of imines. With the complex [Ir(troppCyc)(cod)]OTf, turnover frequencies (TOFs) of >6000 h,1 were reached in the hydrogenation of N -phenyl-benzylidenamine, PhNCHPh. Lower activities (TOF>80 h,1) are observed with N -phenyl-(1-phenylethylidene)amine, PhNCMePh. Chiral tropp-type ligands were prepared in few simple steps. Monosubstitution of the olefinic unit in the dibenzo[a,d]cycloheptenyl moiety with (R)- or (S)-mentholate gave mixtures of diastereomers that could be separated and isolated in enantiomerically pure form. Iridium(I) complexes with these ligands are rare examples of side-on bonded enolether complexes. In catalytic imine hydrogenations, complete conversion (>98,%) was reached in all cases (conditions: p[H2] = 50 bar, T = 50,°C, t = 2 h, substrate/catalyst 100:1). The best enantiomeric excess (ee = 86,% S isomer) was reached with PhNCMePh as substrate and the R,R form of the (10-menthyloxy-5H -dibenzo[a,d]cyclohepten-5-yl)diphenylphosphane ligand. The iridium(I) complex containing the same phosphane gave a 60,% ee (S isomer) with the enamide N-(1-phenylvinyl)acetamide as substrate (conditions: p[H2] = 4 bar, T = 50,°C, t = 18 h, substrate/catalyst = 50:1). These reactions constitute the first examples in which chiral olefins have been used as steering ligands in catalytic enantioselective hydrogenations. [source] Thiourea Based Tweezer Anion Receptors for Selective Sensing of Fluoride IonsCHINESE JOURNAL OF CHEMISTRY, Issue 5 2007You-Ming Zhang Abstract Three 3,3,-di(4-substituted-phenyl)-1,1,-isophthaloylbis(thiourea) compounds were designed as novel neutral anion receptors, and synthesized by simple steps in good yields. The single crystal structure of receptor 1 shows that a solvent molecule was captured by the host molecule through intermolecular hydrogen bonding. Moreover, it was self-assembled as a supramolecular system for the presence of abundant inter- and intramolecular hydrogen bonding and ,-, interactions between phenyl groups. Their application as anion receptors has been examined by UV-Vis and 1H NMR spectroscopy, showing that they had a higher selectivity for fluoride than other halides. The host and guest formed a 1:1 stoichiometry complex through hydrogen bonding interactions in the first step, then following a process of deprotonation in presence of an excess of F, in the solvent of DMF. [source] Study on the Anion Recognition Properties of Synthesized Receptors (III): Convenient Synthesis and Anion Recognition Property of Bisthiosemicarbazone DerivativeCHINESE JOURNAL OF CHEMISTRY, Issue 10 2006You-Ming Zhang Abstract A new series of bisthiosemicarbazone derivative receptors (1, 2 and 3) have been synthesized by simple steps in good yields. Their anion recognition properties were studied by UV-Vis and 1H NMR spectroscopy. The result showed that the receptors 1, 2 and 3 all had a better selectivity to F,, CH3COO, and H2PO4,, but no evident binding with Cl,, Br,, I,, NO3, and HSO4,. Upon addition of the three anions to the receptors in DMSO, the solution acquired a color change from colorless to dark yellow that can be observed by the naked-eyes, thus the receptors can act as fluoride ion sensors even in the presence of other halide ions. The data showed that it was regular that the three receptors had different binding ability with the three anions. For the same anion, the association constants followed the trend: receptor 1>3>2. The UV-Vis data indicates that a 1:1 stoichiometry complex is formed through hydrogen bonding interactions between compound 1, 2 or 3 and anions. [source] Two Multi-armed Neutral Receptors for ,,, -Dicarboxylate AnionsCHINESE JOURNAL OF CHEMISTRY, Issue 4 2006Jin-Long Wu Abstract Two new multi-armed neutral receptors 1 and 2 containing thiourea and amide groups were synthesized by simple steps in good yields. Receptors 1 and 2 have a better selectivity and higher association constants for malonate anion than other anions examined by the present work. In particular, distinct color changes were observed upon addition of dicarboxylate anions to the solution of 1 in DMSO. The UV-Vis and fluorescence spectra data indicate that a 1:2 stoichiometry complex was formed between compound 1 or 2 and dicarboxylate anions of shorter carbon chain, and a 1:1 stoichiometry complex was formed between compound 1 or 2 and dicarboxylate anions of longer carbon chain through hydrogen bonding interactions. [source] | |||||||||||||