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991.
Syed Mashhood Ali Santosh Kumar Upadhyay Arti Maheshwari 《Journal of inclusion phenomena and macrocyclic chemistry》2007,59(3-4):351-355
Desloratadine (DES) is an antihistamine used in the treatment of allergies and chronic urticaria. 1H NMR spectroscopic study of varying ratios of DES and β-Cyclodextrin (β-CD) in D2O suggests the formation of a 1:1 inclusion complex formed by the penetration of Cl-substituted aromatic ring into the β-CD
cavity. The stoichiometry and binding constant of the complex were determined by Scott’s method. 相似文献
992.
An analytical method using alumina modified with water-soluble polyacrylic acid polymer for the simultaneous separation and
preconcentration of trace Cu and Cd in a column system, and their determination by flame atomic absorption spectrometry was
developed. The conditions for coating Al2O3 with polyacrylic acid were optimized, then the column was packed with 50 mg of this sorbent. Cd and Cu solution was passed
through a glass column at pH 4.5, and elution was carried out with 5 mL of 0.05 M HCl at a flow rate of 1 mL min−1. A sorption capacity of 10 mg Cu and 12 mg Cd was obtained for 1 g sorbent. The detection limit was calculated as 4.5 μg L−1 for Cu and 1.54 μg L−1 for Cd in the final solution. Enrichment factors of 300 for Cd and 400 for Cu were obtained. 相似文献
993.
Amir Abbas Matin Ramin Maleki Mir Ali Farajzadeh Khalil Farhadi Reza Hosseinzadeh Abolghasem Jouyban 《Chromatographia》2007,66(5-6):383-387
A new method for extraction and analysis of acetone in human urine based on headspace solid phase microextraction using a
mixture of activated carbon and zeolite as sorbents in a PVC matrix coated on a silver wire and its application to the determination
of ketone bodies is described. Unlike commercial fibers, which are coated on fused silica, the coating adheres strongly to
the silver wire and is thermally stable up to 250 °C. After optimization of coating composition and microextraction conditions
the fiber was used for the analysis of acetone in human urine. 相似文献
994.
It is well known that in any ab initio molecular orbital (MO) calculation, the major task involves the computation of molecular
integrals, among which the computation of Coulomb integrals are the most frequently encountered. As the molecular system gets
larger, computation of these integrals becomes one of the most laborious and time consuming steps in molecular systems calculation.
Improvement of the computational methods of molecular integrals would be indispensable to a further development in computational
studies of large molecular systems. The atomic orbital basis functions chosen in the present work are Slater type functions.
These functions can be expressed as finite linear combinations of B functions which are suitable to apply the Fourier transform method. The difficulties of the numerical evaluation of the analytic
expressions of the integrals of interest arise mainly from the presence of highly oscillatory semi-infinite integrals. In
this work, we present a generalized algorithm based on the nonlinear transformation of Sidi, for a precise and fast numerical evaluation of molecular integrals over Slater type functions and
over B functions. Numerical results obtained for the three-center two-electron Coulomb and hybrid integrals over B functions and over Slater type functions. Comparisons with numerical results obtained using alternatives approaches and an
existing code are listed. 相似文献
995.
Ali M. Ali Ayman H. Ahmed Tarek A. Mohamed Bassem H. Mohamed 《Transition Metal Chemistry》2007,32(4):461-467
New copper(II), nickel(II), iron(III) and palladium(II) Schiff base complexes derived from o-tolidine and selected aldehydes, namely salicyaldehyde and 2-hydroxynaphthaldehyde have been synthesized and characterized
by a combination of elemental analyses, magnetic moments, spectral (u.v.–vis., i.r.) and thermal (tg, dtg) mesurements. The
corrosion inhibition of aluminium and copper in 1 M HCl and chromium–nickel steel in crude oil using N,N′bis(salicyledene)-o-tolidine have been studied by weight loss method. 相似文献
996.
Electroactive conducting copolymers of aniline (ANI) and o-aminophenol (OAP) and two-layered poly(o-aminophenol) (POAP)/polyaniline (PANI) composites were prepared in aqueous acidic solution by electrode potential cycling.
Copolymerization was carried out at different feed concentrations of OAP and ANI on a gold electrode. A strong inhibition
of electropolymerization was found at a high molar fraction of OAP in the feed. The copolymers showed good adherence on the
electrode surface and gave a redox response up to pH=10.0. Two transitions were observed in the in situ conductivities of
the copolymers (as with PANI), but the conductivities were lower by 2.5–3 orders of magnitude as compared to PANI. Electrosynthesis
of PANI on POAP modified electrodes showed copolymer formation after reaction initiation and finally formation of a PANI layer
at the copolymer/solution interface. The ‘memory effect’ of the bilayer structures of both polymers was discussed in terms
of protonation/deprotonation and anion consumption taking place during redox processes of both polymers. 相似文献
997.
Ali Liazid Gerardo F. Barbero Miguel Palma Jamal Brigui Carmelo G. Barroso 《Chromatographia》2007,66(7-8):571-575
Results from a systematic study of the factors affecting extraction of cis-verbenol and verbenone from pine seeds are presented. Five extraction conditions were investigated: extraction solvent, method
of extraction, extraction temperature, volume of solvent, and the ratio of the mass of sample to the amount of extraction
solvent. The resulting optimized method uses magnetic-stirring-assisted extraction of pine seeds (5 g) with ethyl acetate
(75 mL) for 20 min, at room temperature. RSDs were less than 5% for both compounds. GC–FID was used for quantification of
cis-verbenol and verbenone in the extracts. 相似文献
998.
Mohammad Ali Zolfigol Mojtaba Bagherzadeh Shadpour Mallakpour Gholamabbas Chehardoli Arash Ghorbani-Choghamarani Nadiya Koukabi Mina Dehghanian Mahmoudreza Doroudgar 《Journal of molecular catalysis. A, Chemical》2007,270(1-2):219-224
A combination of periodic acid or oxone® and a catalytic amount of KBr in the presence of few drops of water, were used for the catalytic oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogeneous conditions with moderate to excellent yields. 相似文献
999.
In this study, the functionality of maleic anhydride was utilized in the maleic anhydride-styrene-methyl metacrylate (MAStMMA) terpolymer. First, the polyester of poly(ethylene adipate), PEA, polycondensation copolymer was synthesized from ethylene glycol and adipic acid monomers. PEA was then modified on its maleic anhydride units in the MAStMMA terpolymer which has been synthesized previously. This modified copolymer was characterized by FTIR (Fourier Transform Infrared spectroscopy). The viscosimetric and thermomechanical characterization of MAStMMA terpolymer and its modified copolymer were also performed and the results were compared. The modified copolymer obtained was found to be more elastic and more soluble, and had lower viscosity and density. 相似文献
1000.
In this work, two toxic compound, sulfide and thiocyanate were determined simultaneously using kinetic spectrophotometry. These anions have shown the catalytic effects on the reaction between iodine and azide. Since the system was nonlinear, a nonlinear model, principal component-wavelet neural network (PC-WNN) was used as the multivariate calibration method. The principal component analysis was used to decrease the dimension of the original matrix. In other words, the scores of the PCs, 5, instead of the original variables, 301, were used as the input for the model. Two methods were used to select the most relevant principal components: eigenvalue ranking and correlation ranking. In this work, eigenvalue and correlation ranking methods have shown better results for thiocyanate and sulfide, respectively, and it can be concluded that these methods are complementary. The WNN has several advantages relative to other types of neural network such as better convergence ability. The data set was divided to calibration, prediction and validation sets. Each set was selected so that the concentrations of the analytes were approximately covered the entire ranges of the analytes. Mean relative error for thiocyanate and sulfide in validation set were 8.5 and 10.6, respectively. Thiocyanate and sulfide can be determined in the range of 60–700 ng ml−1 and 20–400 ng ml−1, respectively. The proposed method was applied for the determination of sulfide and thiocyanate in real samples such as tap, waste and river waters with satisfactory results. 相似文献