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103.
Joanna S. Stevens Alba C. de Luca Michalis Pelendritis Giorgio Terenghi Sandra Downes Sven L. M. Schroeder 《Surface and interface analysis : SIA》2013,45(8):1238-1246
The C 1 s, N 1 s, and O 1 s core level binding energies (BEs) of the functional groups in amino acids (glycine, aspartic acid, glutamic acid, arginine, and histidine) with varied side‐chains and cell‐binding RGD‐based peptides have been determined and characterized by X‐ray photoelectron spectroscopy with a monochromatic Al Kα source. The zwitterionic nature of the amino acids in the solid state is unequivocally evident from the N 1 s signals of the protonated amine groups and the C 1 s signature of carboxylate groups. Significant adventitious carbon contamination is evident for all samples but can be quantitatively accounted for. No intrinsic differences in the XP spectra are evident between two polymorphs (α and γ) of glycine, indicating that the crystallographic differences have a minor influence on the core level BEs for this system. The two nitrogen centers in the imidazole group of histidine exhibit an N 1 s BE shift that is in line with previously reported data for theophylline and aqueous imidazole solutions, while the nitrogen and carbon chemical shifts reflect the unusual guanidinium chemical environment in arginine. It is shown that the complex envelopes of C 1 s and O 1 s photoemission spectra for short‐chain peptides can be analyzed quantitatively by reference to the less complex XP spectra of the constituent amino acids, provided the peptides are of high enough purity. The distinctive N 1 s photoemission from the amide linkages provides an indicator of peptide formation even in the presence of common impurities, and variations in the relative intensities of N 1 s were found to be diagnostic for each of the three peptides investigated (RGD, RGDS, and RGDSC). Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
104.
Harshanie Abeywardena Aaron R. Jex Simon M. Firestone Sandra McPhee Nicole Driessen Anson V. Koehler Shane R. Haydon Georg von Samson‐Himmelstjerna Melita A. Stevens Robin B. Gasser 《Electrophoresis》2013,34(15):2259-2267
In the present study, we undertook a molecular epidemiological survey of Cryptosporidium and Giardia in calves on three dairy and two beef farms within an open drinking water catchment area (Melbourne, Australia). Faecal samples (n = 474) were collected from calves at two time points (5 months apart) and tested using a PCR‐based mutation scanning‐targeted sequencing phylogenetic approach, employing regions within the genes of small subunit (SSU) of ribosomal RNA (designated partial SSU), 60 kDa glycoprotein (pgp60) and triose phosphate isomerase (ptpi) as genetic markers. Using partial SSU, the C. bovis, C. parvum, C. ryanae and a new genotype of Cryptosporidium were characterised from totals of 74 (15.6%), 35 (7.3%), 37 (7.8%) and 9 (1.9%) samples, respectively. Using pgp60, C. parvum genotype IIa subgenotype A18G3R1 was detected in 29 samples. Using ptpi, G. duodenalis assemblages A and E were detected in totals of 10 (2.1%) and 130 (27.4%) samples, respectively. The present study showed that a considerable proportion of dairy and beef calves in this open water catchment region excreted Cryptosporidium (i.e. subgenotype IIaA18G3R1) and Giardia (e.g. assemblage A) that are consistent with those infecting humans, inferring that they are of zoonotic importance. Future work should focus on exploring, in a temporal and spatial way, whether these parasites occur in the environment and water of the catchment reservoir. 相似文献
105.
Mary E. Neubert Corresponding author Michael R. Fisch Sandra S. Keast Julie M. Kim Mark C. Lohman Rachel S. Murray 《Liquid crystals》2013,40(7):941-963
The typical sidewalls produced in the fabrication of protrusion electrodes are proposed to create a low voltage (4.5 Vrms) and high transmittance (93%) blue-phase liquid crystal display (BP-LCD). The tilted electrodes produce a strong horizontal electrical field that reduces the operating voltage considerably. The common problem of the ‘dead zones’ is solved by reflecting the light onto the electrodes. In order to estimate the phase retardation of the reflected light, a ray tracing simulation program for anisotropic mediums has been developed. The proposed device is more competitive than vertical field switching based BP-LCD and also, has the advantages of protruded in-plane-switching structures. These facts make this technology a potential candidate for the next generation of BP-LCDs. 相似文献
106.
Dr. Sandra Ast Tobias Fischer Holger Müller Dr. Wulfhard Mickler Mathias Schwichtenberg Dr. Knut Rurack Prof. Dr. Hans‐Jürgen Holdt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):2990-3005
In a systematic approach we synthesized a new series of fluorescent probes incorporating donor–acceptor (D‐A) substituted 1,2,3‐triazoles as conjugative π‐linkers between the alkali metal ion receptor N‐phenylaza‐[18]crown‐6 and different fluorophoric groups with different electron‐acceptor properties (4‐naphthalimide, meso‐phenyl‐BODIPY and 9‐anthracene) and investigated their performance in organic and aqueous environments (physiological conditions). In the charge‐transfer (CT) type probes 1 , 2 and 7 , the fluorescence is almost completely quenched by intramolecular CT (ICT) processes involving charge‐separated states. In the presence of Na+ and K+ ICT is interrupted, which resulted in a lighting‐up of the fluorescence in acetonitrile. Among the investigated fluoroionophores, compound 7 , which contains a 9‐anthracenyl moiety as the electron‐accepting fluorophore, is the only probe which retains light‐up features in water and works as a highly K+/Na+‐selective probe under simulated physiological conditions. Virtually decoupled BODIPY‐based 6 and photoinduced electron transfer (PET) type probes 3 – 5 , where the 10‐substituted anthracen‐9‐yl fluorophores are connected to the 1,2,3‐triazole through a methylene spacer, show strong ion‐induced fluorescence enhancement in acetonitrile, but not under physiological conditions. Electrochemical studies and theoretical calculations were used to assess and support the underlying mechanisms for the new ICT and PET 1,2,3‐triazole fluoroionophores. 相似文献
107.
Dr. Jacorien Coetzee Dr. Deborah L. Dodds Prof. Jürgen Klankermayer Sandra Brosinski Prof. Walter Leitner Prof. Alexandra M. Z. Slawin Prof. David J. Cole‐Hamilton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(33):11039-11050
Hydrogenation of amides in the presence of [Ru(acac)3] (acacH=2,4‐pentanedione), triphos [1,1,1‐tris‐ (diphenylphosphinomethyl)ethane] and methanesulfonic acid (MSA) produces secondary and tertiary amines with selectivities as high as 93 % provided that there is at least one aromatic ring on N. The system is also active for the synthesis of primary amines. In an attempt to probe the role of MSA and the mechanism of the reaction, a range of methanesulfonato complexes has been prepared from [Ru(acac)3], triphos and MSA, or from reactions of [RuX(OAc)(triphos)] (X=H or OAc) or [RuH2(CO)(triphos)] with MSA. Crystallographically characterised complexes include: [Ru(OAc‐κ1O)2(H2O)(triphos)], [Ru(OAc‐κ2O,O′)(CH3SO3‐κ1O)(triphos)], [Ru(CH3SO3‐κ1O)2(H2O)(triphos)] and [Ru2(μ‐CH3SO3)3(triphos)2][CH3SO3], whereas other complexes, such as [Ru(OAc‐κ1O)(OAc‐κ2O,O′)(triphos)], [Ru(CH3SO3‐κ1O)(CH3SO3‐κ2O,O′)(triphos)], H[Ru(CH3SO3‐κ1O)3(triphos)], [RuH(CH3SO3‐κ1O)(CO)(triphos)] and [RuH(CH3SO3‐κ2O,O′)(triphos)] have been characterised spectroscopically. The interactions between these various complexes and their relevance to the catalytic reactions are discussed. 相似文献
108.
Dipl.‐Chem. Steffen Styra Dr. Sandra González‐Gallardo Dr. Felix Armbruster Dr. Pascual Oña‐Burgos Dipl.‐Chem. Eric Moos Dr. Matthias Vonderach Priv.‐Doz. Dr. Patrick Weis Priv.‐Doz. Dr. Oliver Hampe Dipl.‐Chem. Anneken Grün Dipl.‐Chem. Yvonne Schmitt Prof. Dr. Markus Gerhards Dipl.‐Chem. Fabian Menges Dipl.‐Chem. Maximilian Gaffga Prof. Dr. Gereon Niedner‐Schatteburg Prof. Dr. Frank Breher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(26):8436-8446
A series of bimetallic silyl halido cuprates consisting of the new tripodal silicon‐based metalloligand [κ3N‐Si(3,5‐Me2pz)3Mo(CO)3]? is presented (pz=pyrazolyl). This metalloligand is straightforwardly accessible by reacting the ambidentate ligand tris(3,5‐dimethylpyrazolyl)silanide ({Si(3,5‐Me2pz)3}?) with [Mo(CO)3(η6‐toluene)]. The compound features a fac‐coordinated tripodal chelating ligand and an outward pointing, “free” pyramidal silyl donor, which is easily accessible for a secondary coordination to other metal centers. Several bimetallic silyl halido cuprates of the general formula [CuX{μ‐κ1Si:κ3N‐Si(3,5‐Me2pz)3Mo(CO)3}]? (X=Cl, Br, I) have been synthesized. The electronic and structural properties of these complexes were probed in detail by X‐ray diffraction analysis, electrospray mass spectrometry, infrared‐induced multiphoton dissociation studies, cyclic voltammetry, spectroelectrochemistry, gas‐phase photoelectron spectroscopy, as well as UV/Vis and fluorescence spectroscopy. The heterobimetallic complexes contain linear two‐coordinate copper(I) entities with the shortest silicon–copper distances reported so far. Oxidation of the anionic complexes in methylene chloride and acetonitrile solutions at ${E{{0\hfill \atop 1/2\hfill}}}$ =?0.60 and ?0.44 V (vs. ferrocene/ferrocenium (Fc/Fc+)), respectively, shows substantial reversibility. Based on various results obtained from different characterization methods, as well as density functional theory calculations, these oxidation events were attributed to the Mo0/MoI redox couple. 相似文献
109.
Dr. Ludovic Fournier Dr. Isabelle Aujard Dr. Thomas Le Saux Sylvie Maurin Sandra Beaupierre Prof. Dr. Jean‐Bernard Baudin Prof. Dr. Ludovic Jullien 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(51):17494-17507
The small and synthetically easily accessible coumarinylmethyl backbone has been modified to generate a family of photolabile protecting groups with redshifted absorption. We relied on introducing electron‐donating groups in the 7 position and electron‐withdrawing groups in the 2‐, and 2‐ and 3 positions. In particular, we showed that the diethylamino‐thiocoumarylmethyl and the diethylamino‐coumarylidenemalononitrilemethyl are relevant for uncaging with cyan light. They both exhibit a significant action cross section for uncaging in the 470–500 nm wavelength range and a low light absorption between 350 and 400 nm. These attractive features are favorable to perform chromatic orthogonal photoactivation with UV and blue‐cyan light sources, respectively. 相似文献
110.
Paula?Reis Luísa?Canto e Castro Sandra?Dias M.?Ivette?GomesEmail author 《Methodology and Computing in Applied Probability》2015,17(1):189-206
In reliability theory any coherent system can be represented as either a series-parallel or a parallel-series system. Its lifetime can thus be written as the minimum of maxima or the maximum of minima. For large-scale coherent systems it is sensible to assume that the number of system components goes to infinity. Then, the possible non-degenerate extreme value laws either for maxima or for minima are eligible candidates for the system reliability or at least for the finding of adequate lower and upper bounds for the reliability. The identification of the possible limit laws for the system reliability of homogeneous series-parallel (or parallel-series) systems has already been done under different frameworks. However, it is well-known that in most situations such non-degenerate limit laws are better approximated by an adequate penultimate distribution. Dealing with regular and homogeneous parallel-series systems, we assess both theoretically and through Monte-Carlo simulations the gain in accuracy when a penultimate approximation is used instead of the ultimate one. 相似文献