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951.
Williams TI Saggese DA Toups KL Frahm JL An HJ Li B Lebrilla CB Muddiman DC 《Journal of mass spectrometry : JMS》2008,43(9):1215-1223
Posttranslational modifications such as glycosylation can play a fundamental role in signaling pathways that transform an ordinary cell into a malignant one. The development of a protocol to detect these changes in the preliminary stages of disease can lead to a sensitive and specific diagnostic for the early detection of malignancies such as ovarian cancer in which differential glycan patterns are linked to etiology and progression. Small variations in instrument parameters and sample preparation techniques are known to have significant influence on the outcome of an experiment. For an experiment to be effective and reproducible, these parameters must be optimized for the analyte(s) under study. We present a detailed examination of sample preparation and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FT-ICR-MS) analysis of O-linked glycans globally cleaved from mucin glycoproteins. Experiments with stable isotope-labeled biomolecules allowed for the establishment of appropriate acquisition times and excitation voltages for MALDI-FT-ICR-MS of oligosaccharides. Quadrupole ion guide optimization studies with mucin glycans identified conditions for the comprehensive analysis of the entire mass range of O-linked carbohydrates in this glycoprotein. Separately optimized experimental parameters were integrated in a method that allowed for the effective study of O-linked glycans. Copyright (c) 2008 John Wiley & Sons, Ltd. 相似文献
952.
Vyas S Ali ME Hossain E Patwardhan S Datta SN 《The journal of physical chemistry. A》2005,109(19):4213-4215
We show that an ethylenic coupler provides a very strong intramolecular magnetic interaction. A recently synthesized nitronyl nitroxide derivative, D-NIT2, is investigated by ab initio quantum chemical methods. The broken symmetry approach yields a coupling constant -541 K that is in good agreement with the observed value in solid state. 相似文献
953.
Cation exchange resin, Amberlite IR-120, has been modified by the sorption of 1-(2-pyridylazo)-2-napthol (PAN) at pH 6.0. The optimum conditions for the sorption of PAN on the resin have been established. The maximum sorption of PAN was found to be 8.70 micromol/g. In order to explore the separation possibilities of the material, distribution coefficients of a number of metal ions were determined in various solvent systems. A number of binary separations of metal ions of analytical interest have been carried out using columns packed with this material. In order to demonstrate the practical utility of this material, Zn2+ and Hg2+ have been selectively separated from synthetic mixtures of metal ions and assay of Zn2+ and Fe2+ in commercially available pharmaceutical tablets; namely Fesofor-Z and FE-Z, was carried out. 相似文献
954.
Haskel D Lang JC Islam Z Cady A Srajer G van Veenendaal M Canfield PC 《Physical review letters》2005,95(21):217207
The magnetic moment reversal at each of the two inequivalent Nd sites in a single crystal of ferromagnetic Nd(2)Fe(14)B is probed by dichroic resonant diffraction of circularly polarized x rays. The results, supported by theory, show that the c-axis intrinsic magnetic stability of this superior permanent magnetic material arises predominantly at one of the Nd sites (g). The other site (f) undermines magnetic stability by favoring a magnetic moment orientation in the basal plane. 相似文献
955.
Underdoped cuprates exhibit a normal-state pseudogap, and their spins and doped carriers tend to spatially separate into 1D or 2D stripes. Some view these as central to superconductivity and others as peripheral and merely competing. Using La(2-x)Sr(x)Cu(1-y)Zn(y)O4 we show that an oxygen isotope effect in Tc and in the superfluid density can be used to distinguish between the roles of stripes and pseudogap and also to detect the presence of impurity scattering. We conclude that stripes and pseudogap are distinct, and both compete and coexist with superconductivity. 相似文献
956.
Jamal N. Islam 《General Relativity and Gravitation》1976,7(8):669-680
A class of approximate stationary solutions of the Einstein-Maxwell equations are obtained by expanding the metric in powers of a certain parameter and solving explicitly the first few orders in terms of four harmonic functions. These solutions, to the order considered, reduce to the Weyl, Bonnor, and Perjés-Israel-Wilson solutions, respectively, for suitable choice of the harmonic functions. They also contain a subclass that is asymptomatically flat and has realistic arbitrary spinning sources. 相似文献
957.
Results are presented for mixed ligand copper(II) complexes of 3,3'-diaminodipropyl-amine and 1,3-diaminopropane studied by electron paramagnetic resonance. The spectra of the complexes in polycrystalline powder form and in frozen solutions of N,N'-dimethyl-formamide indicate that the complexes [Cu(dpt)tn]Cl2·H2O and [Cu(dpt)tn]Br2 have a square based pyramidal CuN5 chromophore and that the complexes [Cu(dpt)tn]I2 and [Cu(dpt)tn](ClO4)2 possess a compressed trigonal bipyramidal CuN5 chromophore. 相似文献
958.
Md Murshed Bhuyan Hirotaka Okabe Yoshiki Hidaka Nirmal Chandra Dafader Nazia Rahman Kazuhiro Hara 《高分子科学杂志,A辑:纯化学与应用化学》2018,55(4):369-376
The objective of the work is to synthesize pectin-N, N-Dimethylacrylamide (DMAA) hydrogel by gamma radiation without using any initiators and cross-linking agents. Effect of radiation doses on gel fraction and equilibrium swelling as a function of pH were studied, and 5 kGy radiation dose was found to be the optimum dose for hydrogel synthesis. The grafting /crosslinking was investigated by Fourier transform infrared spectroscopy. Thermal properties and surface morphology were studied by differential scanning calorimetry and scanning electron microscopy. To study the drug release kinetics, 5-fluorouracil was loaded into the hydrogel and in vitro release was carried out in simulated gastric and intestinal fluid. The release profile of drug showed that more than 90% of the loaded drugs were released after 4 hours at both gastric fluid and intestinal fluid pH. Drug release data was fitted into zero order, Higuchi and Korsmeyer-Peppas kinetic models. Higuchi model was found to be the best fitted and release exponent ‘n’ value of Korsmeyer-Peppas model indicated the non-Fickian transport. 相似文献
959.
Embedding 1D Conducting Channels into 3D Isoporous Polymer Films for High‐Performance Humidity Sensing 下载免费PDF全文
Rahul Shevate Md Azimul Haque Faheem Hassan Akhtar Luis Francisco Villalobos Prof. Tom Wu Prof. Klaus‐Viktor Peinemann 《Angewandte Chemie (International ed. in English)》2018,57(35):11218-11222
Isoporous block copolymer (BCP) films have received exponential interest as highly selective membranes, stemming from their unique morphological features, but their applications in functional devices remain to be realized. Now single‐walled carbon nanotubes (CNTs) were efficiently incorporated into isoporous block copolymer films for chemiresistive sensing at room temperature. Leveraging the efficient charge extraction ability of CNTs together with nanochannel arrays aligned perpendicular to the surface of the films, an ultrafast response time of 0.3 s was achieved for humidity detection with a sensor response of about 800 on changing humidity from 10 % to 95 %. Furthermore, the sensor also responds to various organic vapors, underscoring its promising detection capability. 相似文献
960.
Amiya Atahar M. Yousuf Ali Mollah M. Muhibur Rahman Md. Abu Bin Hasan Susan 《Journal of inclusion phenomena and macrocyclic chemistry》2018,92(3-4):301-309
Two imidazolium-based hexafluorophosphate ionic liquids (ILs), 1-butyl-3-methylimidazolium hexafluorophosphate and 1-dodecyl-3-methylimidazolium hexafluorophosphate, were used to form inclusion complexes (ICs) with α- and β-cyclodextrins (CDs). Formation of the ICs of each CD with each IL was confirmed by the appearance of a characteristic peak in the UV region. Characterisation of the ICs by NMR and FT-IR spectroscopy provided information about the interactions between the host and guest molecules and the structure of the ICs. Temperature-dependent particle size analysis by dynamic light scattering suggested that the size of the host and the guest governs their stability. 相似文献