摘要:

AbstractWe synthesized Leu‐Arg‐Pro‐Val‐Ala‐Ala‐Glu, the peptide contained in lactoferrin (Lf), to identify the angiotensin converting enzyme (ACE) inhibition. In an attempt to know the structure‐activity relationship of this peptide, we replaced Pro (the third amino acid residues from N‐terminal) or Val (the fourth amino acid residues from N‐terminal) with Ala (neutral amino acid), Glu (acidic amino acid) or Lys (basic amino acid) to produce six peptides. From the in vitro ACE inhibition (IC50) of these synthesized peptides, the original peptide (Leu‐Arg‐Pro‐Val‐Ala‐Ala‐Glu) showed higher ACE inhibition than the replaced six peptides. Thus, replacement of Pro at the third amino acid residues or Val at the fourth position with Ala, Glu or Lys revealed the ACE inhibition to be lower than the original form of Leu‐Arg‐Pro‐Val‐Ala‐Ala‐Glu. Otherwise, we added one peptide at the C‐terminal of Leu‐Arg‐Pro‐Val‐Ala‐Ala‐Glu and found both products with an addition of Val (Leu‐Arg‐Pro‐Val‐Ala‐Ala‐Glu‐Val) or Ile (Leu‐Arg‐Pro‐Val‐Ala‐Ala‐Glu‐Ile) showing a lower ACE inhibition than the original one. The ACE inhibitions produced by both replaced peptides were without significance. Also, deletion of the last peptide at the C‐terminal (Leu‐Arg‐Pro‐Val‐Ala‐Ala) failed to produce a marked change of ACE inhibition as compared to the original one. The

ISSN:0009-4536    

DOI:10.1002/jccs.200600068

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractDensity‐functional theory method (DFT) B3LYP/6–311++G(3df,2pd) and Moller‐Plesset perturbation method (MP2) MP2/6–311++G(3df,2pd) of Gaussian 03 were selected for the theoretical study of weakly bound CO2—HF complex. In addition to the well‐known linear structure, the various bent structure complexes were also found in this work. The self‐consistent energy differences were only around 0.02 kJ/mol between the bent structure and linear structure by comparison. From the results of H‐bonding distance, dHF elongation and red shift of VHF vibration frequency, all the evidence shows that the H‐bonding effect in the bent structure is stronger than the linear structure. However, if one compares the Gibbs energy of the complex formation by temperature variation, it is very easily found that the linear form is favored under the thermal conditions of most temperatures whenever T ≥ 40 K. Such a fact is consistent with the former spectroscopic observed result

ISSN:0009-4536    

DOI:10.1002/jccs.200600069

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractThe viscosities, η, and refractive indices, n, of pure dimethylsulphoxide (DMSO), benzene, toluene,o‐xylene,m‐xylene,p‐xylene and mesitylene, and those of their 54 binary mixtures, with DMSO as common component, covering the whole composition range have been measured at 298.15, 303.15, 308.15, 313.15, and 318.15 K. From the experimental data, the deviations in viscosity, Δη and deviations in molar refraction, ΔRmhave been calculated. The variation of these parameters with composition and temperature of the mixtures have been discussed in terms of molecular interaction in these mixtures. The effect of the number and position of the methyl groups in these aromatic hydrocarbons on molecular interactions in these mixtures has also been discussed. The free energies, ΔG*, enthalpies, ΔH*and entropies, ΔS*of activation of viscous flow have also been obtained by using Eyring viscosity equation. The ΔH*values were found independent of temperature. The dependence of these thermodynamic parameters on composition of the mixtures has been discussed. Further, the viscosities and refractive indices of these binary mixtures were calculated theoretically from pure component data by using various empirical and semi‐empirical relations and the results were compared with the experi

ISSN:0009-4536    

DOI:10.1002/jccs.200600070

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractOxidative deprotection of a variety of trimethylsilyl ethers were performed by Fe(NO3)3.9H2O in the presence of H3PMo12O40.xH2O as catalyst at room temperature in good to high yields under solvent‐free condition

ISSN:0009-4536    

DOI:10.1002/jccs.200600071

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractA facile, reliable and reproducible method for speciation and determination of the traces amounts of chromium(III) in waste water has been developed. The method was based on complex formation on the surface of the ENVI‐18 DSK™disks followed by stripping of the retained species by minimum amounts of appropriate organic solvents. The elution was efficient and quantitative. The effects of potential interfering ions, pH, ligand amount, stripping solvent, and sample flow rate were also investigated. Under the optimal experimental conditions, the break‐through volume was found to be about 1500 mL providing a preconcentration factor of 300. The maximum capacity of the disks was found to be 225 ± 3.9 μg for Cr3+. A limit of detection of 0.02 ng.mL−1was obtained, and the method was applied for determination of chromium in electroplating industries waste water located in the eastern regions

ISSN:0009-4536    

DOI:10.1002/jccs.200600072

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractLithium vanadium bronzes with composition formula LixV2O5(0.04 ≤ × ≤ 0.92) have been prepared by solid‐state reaction at 650 °C in argon atmosphere. The obtained products were characterized by X‐ray powder diffraction and IR spectroscopy. The results reveal that four phases are present in the range from x = 0.04 to 0.92, namely α, β, β′, and γ phase. The magnetic susceptibility for the investigated bronzes was measured using the conventional Gouy's method. The values of the effective magnetic moments, as calculated from experimental data, indicate the presence of V4+ions in all bronze samples. The electrical conductivity as a function of temperature and lithium content was measured in the temperature range from room temperature to 483 K. The electrical conductivity of the bronzes is found to be affected by lithium content. The values of the electrical conductivity increase with temperature for the prepared samples and both electronic and ionic conductio

ISSN:0009-4536    

DOI:10.1002/jccs.200600073

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractThe adsorption and reactions of CHCl3on three commercially available TiO2powders have been investigated by Fourier transform infrared spectroscopy in a gas‐solid reaction system. Probably, owing to the difference in surface morphology, CHCl3is weakly adsorbed on two of the three TiO2samples at 35 °C. But, as the more reactive TiO2is exposed to CHCl3at 35 °C, the surface is found to be covered with CHCl3, HCOO, H2O, and CO. In addition to these surface species, gaseous HCl and CO are generated at higher temperatures. Photoirradiation of CHCl3on TiO2in the absence or presence of O2causes the decomposition of CHCl3. This photoprocess is enhanced in

ISSN:0009-4536    

DOI:10.1002/jccs.200600074

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractAn amperometric cholesterol biosensor based on immobilization of cholesterol oxidase in a Prussian blue (PB)/polypyrrole (PPy) composite film on the surface of a glassy carbon electrode was fabricated. Hydrogen peroxide produced by the enzymatic reaction was catalytically reduced on the PB film electrode at 0 V with a sensitivity of 39 μA (mol/L)−1. Cholesterol in the concentration range of 10−5˜ 10−4mol/L was determined with a detection limit of 6 × 10−7mol/L by amperometric method. Normal coexisting compounds in the bio‐samples such as ascorbic acid and uric acid do not interfere with the determination. The excellent properties of the sensor in sensitivity and selectivity are attributed to the PB/PPy layer modified o

ISSN:0009-4536    

DOI:10.1002/jccs.200600075

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractThe chemical pollutants 2‐nitrophenol (2‐NP) and 2,4,6‐trinitrophenol (2,4,6‐TNP) were studied for their separation from water by the paper capillary permeation adsorption technique by the use of the four cationic surfactants dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium bromide (TTAB), cetyltrimethylammonium bromide (CTAB), cetylpyridinium chloride (CPC) as regulators. The effect of pH and the concentration of surfactant on the separatability have been investigated. A nearly 100% separatability was obtained for each pollutant at its optimum pH and surfactant concentration. It was shown that the separation was accomplished via surface adsorption onto the fibers of paper. The change in separatability at basic pH 11 with surfactant variety was analyzed. The result shows that the surfactant with a longer chain alkyl group is more effective for the separation of 2‐NP and the surfactants with 16 carbons in the long chain alkyl group are most effective. The surfactants with 12 carbons or more in the long alkyl group but containing no aromatic group such as pyridyl group are equally effective for accomplishing an efficient separation of 2,4,6‐TNP. Selective separation of 2‐NP from an admixture of 2‐NP plus 2,4,6‐TNP was attempted. The optimum surfactant for each pollutant was tested with seawater for removing the pollutant. The goal of this study is to search for an optimum cationic surfactant and optimum separation conditions

ISSN:0009-4536    

DOI:10.1002/jccs.200600076

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY

摘要:

AbstractA new inhibitory reaction is proposed and a kinteic method developed for the determination of ultra‐micro amounts of Mo(VI) on the basis of its inhibitory activity in oxidation of trimethylenediamine ‐N,N,N′,N′‐tetraacetic acid (TDTA) by KMnO4in the presence of hydrochloric acid. Under optimal conditions the sensitivity of the method is 0.5 ng/cm3. The probable relative error is 2.9–3.5% for the concentration range 7.5–2.0 ng/cm3of Mo(VI). The effect of certain foreign ions upon the reaction rate were determined for the assessment of the selectivity of the method. The selectivity of the method is relatively good. Kinetic equations were proposed for the investigated process. A method has been applied for determination of Mo(VI) in a certain

ISSN:0009-4536    

DOI:10.1002/jccs.200600077

出版商:WILEY‐VCH Verlag    

年代:2006

数据来源: WILEY