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91.
The Q-TG mass loss and first derivative Q-DTG mass loss accompanying benzene thermodesorption from silica gel samples under
quasi-isothermal conditions were studied with a Derivatograph Q-1500 D (MOM, Hungary). The isotherms of adsorption-desorption
of benzene vapour on different porous silica gels were measured gravimetrically by using a McBain balance. The benzene mass
loss in the adsorption region, obtained from the Q-TG curves, and the adsorption capacity, established gravimetrically, exhibited
a satisfactory correlation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
92.
The reaction of MoO2Cl2(OPMePh2)2 with t-butylhydroperoxide (TBHP) in the presence of cis-cyclooctene yields the tetrameric complex Mo4O6(O2)2(μ3-O)2{(μ2-O,μ3-OC8H14}2(OPMePh2)2, (1). Additionally in the absence of cis-cyclooctene MoO(O2)Cl2(OPMePh2)2, MoO(O2)2(H2O)(OPMePh2), (2), and two novel yellow compounds can be isolated depending on the quantity of TBHP used and the reaction conditions. Both the starting material MoO2Cl2(OPMePh2)2 and tetramer 1 are capable of accomplishing the epoxidation of cis-cyclooctene as catalysts. The single crystal X-ray determined structures of complexes 1 and 2 are reported.Dedicated to Professor F. A. “Chief” Cotton on the occasion of his 75th birthday 相似文献
93.
Peptides bound to MHC molecules on the surface of cells convey critical information about the cellular milieu to immune system T cells. Predicting which peptides can bind an MHC molecule, and understanding their modes of binding, are important in order to design better diagnostic and therapeutic agents for infectious and autoimmune diseases. Due to the difficulty of obtaining sufficient experimental binding data for each human MHC molecule, computational modeling of MHC peptide-binding properties is necessary. This paper describes a computational combinatorial design approach to the prediction of peptides that bind an MHC molecule of known X-ray crystallographic or NMR-determined structure. The procedure uses chemical fragments as models for amino acid residues and produces a set of sequences for peptides predicted to bind in the MHC peptide-binding groove. The probabilities for specific amino acids occurring at each position of the peptide are calculated based on these sequences, and these probabilities show a good agreement with amino acid distributions derived from a MHC-binding peptide database. The method also enables prediction of the three-dimensional structure of MHC-peptide complexes. Docking, linking, and optimization procedures were performed with the XPLOR program [1]. 相似文献
94.
Blayne M. McKenzie Rudy J. Wojtecki Kelly A. Burke Patrick T. Mather Stuart J. Rowan 《Tetrahedron》2008,64(36):8488-8495
A versatile one-pot synthetic platform for the preparation of a range of functionalized 2,6-bisbenzimidazolylpyridine (Bip) derivatives is presented. This protocol significantly reduces the cost and time of previous synthetic routes, while facilitating scale up to multi-gram quantities in good yields (63-90%). The previous synthetic methodology was improved through judicious choice of the reducing agent and solvent in the reduction/ring-closing step. Via this platform, we also successfully accessed a mesogenic Bip ligand and herein report initial liquid crystalline properties of this derivative. 相似文献
95.
Rudy Simons Jean‐Paul Vincken Edwin J. Bakx Marian A. Verbruggen Harry Gruppen 《Rapid communications in mass spectrometry : RCM》2009,23(19):3083-3093
Due to their substitution with an isoprenoid group, prenylated flavonoids have an increased affinity for biological membranes and target proteins, enhancing their potential bioactivity. Although many prenylated flavonoids have been described, there are no methods that specifically screen for their presence in complex mixtures, prior to purification. We describe a method based on ultra‐high‐performance liquid chromatography (UHPLC) with electrospray ionisation mass spectrometry (ESI‐MS) that allows rapid screening for prenylated flavonoids in multi‐component plant extracts. Identification of the prenylated flavonoids is based on screening for neutral losses of 42 u and 56 u in the positive‐ion mode MS2 and MS3 spectra within the MS chromatograms. In addition, this method discriminates between a prenyl chain and a ring‐closed prenyl (pyran ring), based on the ratio of the relative abundances of the ions that lose 42 u and 56 u (42:56). The application of this screening method on a 70% aq. ethanol, ethanol and ethyl acetate extract of the roots of Glycyrrhiza glabra indicated the presence of 70 mono‐ and di‐prenylated flavonoids. In addition, of each prenylated flavonoid the type of prenylation, chain or pyran ring was determined. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
96.
Rudy Hofmeister 《Fiber and Integrated Optics》2013,32(3):245-248
The sensitivity of a fiber-optic strain gauge that makes use of interference between the orthogonal linearly polarized eigen-modes propagated in a length of highly birefringent single-mode fiber is primarily determined by tension-induced modal birefiringence ΔB. This ΔB is in a close relationship with the ellipticity of the jacket surrounding the core, on which anisotropic residual stresses are imposed, but ΔB does not depend definitely on the beat length of fiber. Dependence of AB on Young's modulus and the Poisson ratio are computed and discussed in association with the measured results. 相似文献
97.
98.
Linsheng Feng Eugenijus Urnezius Rudy L. Luck 《Journal of organometallic chemistry》2008,693(8-9):1564-1571
The dioxo molybdenum and tungsten complexes MoO2Cl2(OPPh2CH2OH)2 and WO2Cl2(OPPh2CH2OH)2 have been synthesized and characterized by FT-IR, 1H and 31P NMR. Their structures, as determined by single crystal X-ray diffraction analysis, reveal distorted octahedral geometries with cis terminal oxygen atoms, trans Cl ligands and that the hydroxymethyldiphenylphosphine oxide ligands coordinate through the oxygen atom bonded to the P atom. Both of the compounds are studied as catalysts for the epoxidation of cis-cyclooctene in the presence of hydrogen peroxide as a source of oxygen. Both complexes showed good activity and very high selectivity for the formation of cyclooctene oxide. 相似文献
99.
Joél Smet Sara Seneca Boel De Paepe Ann Meulemans Helene Verhelst Jules Leroy Linda De Meirleir Willy Lissens Rudy Van Coster 《Electrophoresis》2009,30(20):3565-3572
Complex V, site of the final step in oxidative phosphorylation, uses the proton gradient across the inner mitochondrial membrane for the production of ATP. It is a multi‐subunit complex composed of a catalytic domain (F1) and a membrane domain (F0) linked by two stalks. Subcomplexes of complex V containing the F1 domain have previously been reported in small series of patients. We report the results in tissue samples and/or cultured skin fibroblasts studied by blue native PAGE followed by activity staining in the gel. Catalytically active subcomplexes of complex V were detected in 66 tissues originating from 53 patients. In 29 of the latter (55%), a mitochondrial DNA (mtDNA) defect was identified. Twelve patients had a pathogenic point mutation in a mitochondrial tRNA, one a large mtDNA deletion, 12 showed mtDNA depletion and four had a mutation in the MT‐ATP6 gene. We conclude that the presence of subcomplexes of complex V is a valuable indicator in the detection of mtDNA defects. 相似文献
100.
Pogány P Kovács A Varga Z Bickelhaupt FM Konings RJ 《The journal of physical chemistry. A》2012,116(1):747-755
The electronic structure and various molecular properties of the actinide (An) dicarbides ThC(2) and UC(2) were investigated by relativistic quantum chemical calculations. We probe five possible geometrical arrangements: two triangular structures including an acetylide (C(2)) moiety, as well as the linear AnCC, CAnC, and bent CAnC geometries. Our calculations at various levels of theory indicate that the triangular species are energetically more favorable, while the latter three arrangements proved to be higher-energy structures. Our SO-CASPT2 calculations give the ground-state molecular geometry for both ThC(2) and UC(2) as the symmetric (C(2v)) triangular structure. The similar and, also very close in energy, asymmetric (C(s)) triangular geometry belongs to a different electronic state. DFT and single-determinant ab initio methods failed to distinguish between these two similar electronic states demonstrating the power of multiconfiguration ab initio methods to deal with such subtle and delicate problems. We report detailed data on the electronic structure and bonding properties of the most relevant structures. 相似文献