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101.
Zarei M Bindila L Souady J Dreisewerd K Berkenkamp S Müthing J Peter-Katalinić J 《Journal of mass spectrometry : JMS》2008,43(6):716-725
Matrix-assisted laser desorption/ionization (MALDI) process of sialoglycoconjugates is generally accompanied by different levels of cleavage of sialic acid residues and/or by dehydration, and decarboxylation reactions. Quantitative densitometry of the mouse brain ganglioside (MBG) components separated by high-performance thin layer chromatography (HPTLC) and evidenced by orcinol staining was a basis to verify the ganglioside composition pattern with respect to the relative abundances of individual components in the mixture. A systematic mass spectrometry (MS) sialylation analysis has been carried out to evaluate the feasibility of an axial time-of-flight (a-TOF) MS, equipped with a vacuum MALDI source and an orthogonal-TOF (o-TOF) instrument with an ion source operated at about 1 mbar of N(2). Besides, the esterification by one methyl group of the carboxyl group in sialic acid to increase the stability of the ganglioside species for MALDI MS analysis has been tested and the yield of intact ganglioside species and of the neutral loss of water and carbon dioxide estimated. For the sialylation analysis of native ganglioside mixtures the MALDI o-TOF analysis with 6-azo-2-thiothymine/diammonium citrate (ATT/DAC) as a matrix appears as an optimal approach for ganglioside profiling. 相似文献
102.
Horst Böttcher Boris Mahltig Jamal Sarsour Thomas Stegmaier 《Journal of Sol-Gel Science and Technology》2010,55(2):177-185
The preparation of TiO2-coated polyester fabrics for purposes of photocatalytic water purification requires coating agents with crystalline TiO2 particles preferably in the anatase modification. The resulting coatings should exhibit a high water resistance and high
photocatalytic activity according to reaction with structurally different dyestuffs. For this, the synthesis of anatase sols
by hydrolysis of tetraisopropyltitanate in acidic medium under reflux was optimized. By precoating or addition of polymeric
epoxysilanes a good adhesion on the polyester support could be realized. The photocatalytic activity was tested with different
dyestuffs as: Methylene blue, Rhodamine B and the azo dyes AcidOrange 7 and C.I. Reactive red 158. The rate of photodestruction
depends strongly on the type of used dye and its structure. Surprisingly, no differences in photodegradation were found in
case of investigations with Rhodamine B, if the photoreaction is performed under exposure with UV or with visible light. A
possible explanation of the similar behavior of photoreaction under different light sources could be a photodestruction by
electron transfer from Rhodamine B to TiO2. Therefore, Rhodamine B seems to be generally not suitable for the evaluation of the photoactivity of TiO2 under irradiation with visible light. 相似文献
103.
Paul P. Horley Vítor R. Vieira Peter M. Gorley Vitalii K. Dugaev Jamal Berakdar Józef Barna? 《Journal of magnetism and magnetic materials》2010,322(9-12):1373-1376
One of the important requirements for spintronic devices concerns an efficient magnetization reversal, which may eventually lead to ultra-fast non-volatile magnetic memory applications. In particular, it is necessary to achieve stable sub-nanosecond switching times and to reduce magnetization “ringing”, so that the reversal will proceed along the shortest ballistic path connecting the initial and the target magnetization states. This paper is dedicated to the numerical simulations of a mono-domain ferromagnetic particle, described by the Landau–Lifshitz–Gilbert equation. We study the general case of arbitrary orientation of the applied field/current pulses, constructing dynamic diagrams for the reversal time. We have found that even short 50 ps pulses, applied at a proper angle, will induce magnetization reversal with minimal ringing effects. 相似文献
104.
105.
Assist. Prof. Dr. Sumbal Saba Caio R. Dos Santos Bruno R. Zavarise Aline A. S. Naujorks Marcelo S. Franco Alex R. Schneider Marcos R. Scheide Dr. Ricardo F. Affeldt Assoc. Prof. Dr. Jamal Rafique Prof. Dr. Antonio L. Braga 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(20):4461-4466
Herein, a greener approach to the eosin Y-Na2 catalyzed, C(sp2)−H bond azo coupling of imidazoheteroarene with aryl diazonium salts is described, under acid free conditions. This direct photoredox process resulted in the corresponding azo products in good to excellent yields. Besides, this new approach could also be applicable to anilines, which is a poorly reactive substrate by other methods. The main features of this reaction are that it provides high yields and is gram-scalable and applicable to biologically relevant imidazoheteroarenes and -anilines. 相似文献
106.
通过离子液体氯化1-苄基-3-甲基咪唑(BenzMeIm-Cl)与PtCl2的反应,合成了配合物(BenzMeIm)2[PtCl4],并用元素分析、红外光谱、紫外-可见光谱、1H NMR、13C NMR和单晶X射线衍射对其进行了表征。单晶X射线分析表明,配合物结构属于P21/c空间群,晶胞参数和结构解析参数为:a=0.981 80(5)nm,b=0.861 47(3)nm,c=0.144 332(7)nm,β=92.480(2)°,V=121.96(1)nm3,R1=0.014 4,wR2=0.038 8。 相似文献
107.
Mukhopadhyay S Lasri J Charmier MA da Silva MF Pombeiro AJ 《Dalton transactions (Cambridge, England : 2003)》2007,(45):5297-5304
[2 + 3] Cycloaddition reactions of the diazidoplatinum(II) complexes cis-[Pt(N3)2(PPh3)2] 1 and cis-[Pt(N3)2(2,2'-bipy)] 4 with organonitriles NCR 2 give the bis(tetrazolato) complexes trans-[Pt(N4CR)2(PPh3)2] 3 [R = Me (3a), Et (3b), Pr (3c), Ph (3d), 4-ClC6H4 (3e)] and cis-[Pt(N4CR)2(2,2'-bipy)] 5 [R = Me (5a), Et (5b), Pr (5c), Ph (5d)]. The reaction of cis-[Pt(N3)2(PPh3)2] I with propionitrile also affords, apart from 3b, the unexpected mixed cyano-tetrazolato complex trans-[Pt(CN)(5-ethyltetrazolato)(PPh3)2] 3b' which is derived from the reaction of the bis(tetrazolato) 3b with propionitrile, with concomitant formation of 5-ethyl-1H-tetrazole, via a suggested unusual oxidative addition of the nitrile to PtII. All these reactions are greatly accelerated by microwave irradiation and this method also shows a higher selectivity in the case of the reaction of propionitrile with 1, leading only to the formation of 3b. All the complexes obtained were characterized by IR, 1H, 13C and 31P[1H] (for complexes 3) NMR spectroscopies, FAB-MS and elemental analyses. Complexes 3b', 3d, 3e and 5d were also characterized by X-ray structural analyses. 相似文献
108.
On-line flow injection solid sample introduction, leaching and potentiometric determination of fluoride in phosphate rock 总被引:1,自引:0,他引:1
Sweileh JA 《Analytica chimica acta》2007,581(1):168-173
A flow injection method with on-line solid sample dissolution was developed for the determination of fluoride in phosphate rock. The fluoride was selectively leached (98-102.4 % recovery) from a 50-mg powdered phosphate rock sample with 0.50 M citric acid. Using the zone sampling technique the fluoride in the buffered leachate was determined by injecting 87 μL into the carrier stream using a fluoride ion-selective electrode detector. The sensing element of the electrode was housed in a home-made sleeve-type flow-through cell. On-line solid sample digestion with 0.50 M citric acid at 55 °C resulted in minimum dissolution of interfering iron and aluminum ions with improved accuracy and calibration linearity. The incorporation of relatively high level of fluoride in the carrier stream (40 μg mL−1) facilitated the determination of high levels of fluoride in phosphate rock (up to 4.1%) with out the need for excessive on-line dilution.The optimized flow system was applied for the determination of fluoride in phosphate rocks samples and a reference material at a rate of nine samples per hour with a relative standard deviation (n = 5) of 2.95-4.0 %. Comparison of the proposed flow injection method with the standard method, which involves steam distillation from sulfuric acid solution and manual titration with thorium nitrate, showed no evidence of bias at the 95% confidence level. 相似文献
109.
Mahmoud Sunjuk Bassam El-Eswed Jamal N. Dawoud Amneh Shtaiwi Monther Khanfar Mohammad El-Khateeb 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):558-575
Abstract Lithium complexes were prepared with phenylphosphinic and phenylphosphonic acids. The complexes were studied in the solid state using Fourier transform infrared spectroscopy spectroscopy and in solution (methanol) using 1H, 13C, and 31P Nuclear magnetic resonance spectroscopy (NMR) spectroscopy; the most preferred structures of the complexes were determined by density functional theory (DFT) computational method. Although methanol has a strong solvation effect on lithium ions and ligands, which causes dissociation of the complexes, significant changes of the NMR spectra of the complexes (relative to those of the free ligands) were observed. The new spectroscopic results indicate the presence of the phenylphosphinic acid tautomer (I: C6H5PH(?O)OH) rather than that of phenyl-phosphorous acid (II: C6H5P(OH)2) in deuterated methanol showing PH/PD exchange. On the other hand, tautomer I predominates in the complex with lithium without showing PH/PD exchange. The DFT calculations predict that tautomer I is the preferred structure in the case of free ligand and lithium complex. The absence of a PH/PD exchange in the complex is due to the formation of a chelating complex, rather than of a simple salt between lithium ion and the two oxygen atoms of I, which prevent tautomerization of I into II. DFT calculations support the formation of lithium chelating complexes. The lithium ion was found to affect the spectroscopic properties of phenylphosphinic acid more dramatically than those of phenylphosphonic acid. 相似文献
110.
Synthesis and characterization of new soluble thermally stable poly(azomethine‐ether‐imide)s: discerning the possibility for high temperature applications 下载免费PDF全文
Rubbia Iqbal Muhammad Kaleem Khosa Muhammad Asghar Jamal Sadia Ilyas Muhammad Tahir Hussain Mazhar Hamid 《先进技术聚合物》2016,27(2):221-227
A new series of polyimides was synthesized by the condensation of monomers (azomethine‐ether diamine, DA‐1 and DA‐2) with pyromelliticdianhydride (PMDA), 3,4,9,10‐perylenetetracarboxylic dianhydride (PD) and 3,3′4,4′‐benzophenonetetracarboxylic dianhydride (BD). The structural explications of monomers and polyimides was conducted by FT‐IR, 1H NMR and elemental analysis. All polyimides were found soluble in polar aprotic solvents and found to be semicrystalline in nature confirmed by XRD. The inherent viscosities were found in the range of 0.67–0.77 g/dl. %. Average molecular weight (MW) and number average molecular weight (Mn) of the polyimides were found in the range of 5.72 × 105 g/mol–6.58 × 105 g/mol and 3.79 × 105 g/mol 4.11 × 105 g/mol respectively. The polyimides exhibited excellent thermal properties having a glass transition temperature Tg in the range of 230–290°C and the 10% weight loss temperature was above 450°C. The values of thermodynamic parameters, activation energy, enthalpy and entropy fall in the range of 45.2–53.90 kJ/mol, 43.5–52.30 kJ/mol and 0.217 kJ/mol k to 0.261 kJ/mol k respectively. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献