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  • 1
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; Supercritical fluid Chromatography ; Light scattering detection ; Pharmaceutical analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The evaporative light scattering detector (ELSD) has been used in pharmaceutical analysis by liquid and supercritical fluid chromatography. An ELSD equipped with interchangeable interfaces enables the use of various eluents (UV- or non-UV-absorbing) in isocratic or gradient mode. Analyses were performed on several non-UV-absorbing excipients and active substances. The narrow spread of the response factors of the various compounds investigated has indicated that the detector is suitable for direct raw quantitation of unknown samples in stability studies.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; Beet ; Carbohydrates ; Light scattering detection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An evaluation of the most commonly used HPLC system (reversed phase octadecyl sillica gel) was undertaken in order to determine the level of certain carbohydrates in molasses produced in the refining of sugar beet. Chromatographic parameters and purification operations prior to analysis are discussed in order to develop an analytical method permitting automation of sugar determination. A Zorbax ODS column (250 × 9.4 mm), water elution, and light scattering detection allow easy determination of glucose + fructose, sucrose, and raffinose in molasses using an internal standard (maltose).
    Additional Material: 6 Ill.
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  • 3
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dispersion of monosized drops downstream a point injection in a grid-generated turbulence is studied. Influence of extra bodyforces is also investigated by use of ferrofluid drops and magnetic field. Datas are obtained through LDV and given for fluid and particles mean and fluctuant velocities. Presence probability repartition for particles downstream the injection is obtained by LDV counting.
    Additional Material: 10 Ill.
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  • 4
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In the absence of vitamin K or in the presence of the vitamin K antagonists, abnormal nonfunctional forms of prothrombin circulate in the blood. A reliable and reproducible technique, derived from traditional crossed affinoimmunoelectrophoresis in presence of calcium lactate, was developed and optimized. The technique is based on nondenaturing polyacrylamide gel affinoelectrophoresis, with calcium lactate, of plasma samples, followed by immunoblotting with rabbit anti-human prothrombin serum and detection with an anti-rabbit immunoglobulin peroxidase conjugate. Depending on the plasmas, one or two bands were visualized and quantified by densitometry of the immunoblots. The technique was able detect abnormal des-gamma-carboxylated prothrombins at concentration of 0.1 μg/mL.
    Additional Material: 3 Ill.
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  • 5
    ISSN: 0170-2041
    Keywords: Housane ; Norcaradiene ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloaddition of a Very Reactive Cyanovinylcarbene with Benzene and 3,4-Dichlorocyclobutene. Molecular and Crystal Structure of 2,3-Dichloro-5-(1-cyano-2-methyl-1-propenyl)-5-housanecarbonitrile and 7-(1-Cyano-2-methyl-1-propenyl)-7-norcaradienecarbonitrileThe cyanovinylcarbene 2 has been generated by photolysis of 3,3-dimethyl-3H-pyrazole-4,5-dicarbonitril (1) and the cycloaddition products with benzene and with 3,4-dichlorocyclobutene have been isolated. The molecular structures of the cycloaddition products 7-(1-cyano-2-methyl-1-propenyl)-7-norcaradienecarbonitrile (3) and 2,3-dichloro-5-(1-cyano-2-methyl-1-propenyl)-5-housanecarbonitrile (4) were determined by X-ray analyses. The bridging bond of the bicyclo[2.1.0]pentane group in 4 is shortened to 1.515 Å by the electronic interaction of this group with the cyano substituent. The vinyl substituent has no influence because of perpendicular orientation.
    Additional Material: 2 Ill.
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  • 6
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron impact ionization-collision-induced dissociation (EI-CID) and negative ion chemical ionization-collision-induced dissociation (NICI-CID) experiments have been performed on the molecular or quasi-molecular ions (M+· or [M - H]-) of series of terpenoid alcohols, using a Fourier transform ion cyclotron resonance spectrometer. These terpenes belong to the p-menthane family and bear a hydroxyl group in various positions relative to the isopropyl or isopropenyl substituent (positional or stereochemical isomers). In the case of positional isomers, different CID spectra were always obtained. Within a given diastereoisomeric series, stereochemical differences were also observed in both NICI-CID and EI-CID experiments.
    Additional Material: 2 Ill.
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  • 7
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; Carbohydrates ; Light scattering detector ; Automatic analysis ; Prepurification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sugar analysis in the beet industry presents some difficulties due to the highly complex composition of the raw products. This is particularly important in molasses, which contains a considerable ionic component. However, precise determination of raffinose concentration is necessary to optimize the crystallization process. Purification of raw products on mixed-bed ion exchangers followed by passage through a ODS precolumn is performed before the actual chromatographic step. These steps must be automated in order to improve precision and productivity. A completely automatic system, designed for maximum stability of chromatographic columns and good analytical precision of results is presented.
    Additional Material: 7 Ill.
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  • 8
    ISSN: 0935-6304
    Keywords: HPLC ; Glucosinolate analysis ; Desulfated glucosinolates ; Synthetic glucosinolates ; Rapeseed ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separation of new, artificial, non-sulfated glucosinolates and desulfated natural glucosinolates on different apolar (C8, TMS, phenyl) or weakly polar (CN) bonded stationary phases by gradient elution has shown that apolar or weakly polar bonded silica-based adsorbents, in addition to the C8 phase chosen for the standard procedure, can be used with benefit for the analysis of glucosinolate mixtures.The use of new artificial glucosinolates, not present in cruciferae, as internal standards for the standard HPLC method for the determination of the main glucosinolate composition and content of rapeseed is discussed.The main factors influencing the retention and selectivity toward several natural and artificial non-sulfated glucosinolates for different chromatographic systems have been studied, and for additional information the retention data have been analyzed statistically by factor analysis.The first results from this study show that the mechanism of the HPLC retention of glucosinolates is the sum of only two methematically independent physico-chemical phenomena. The first is associated with the hydrophobicity of compounds.A better understanding of the chromatographic behavior of glucosinolates has made it possible to investigate the synthesis of new, artificial standard glucosinolates with the intention of providing an ideal standard for every kind of analysis. It also supplies a tool to enable laboratories to choose the best chromatographic system for a particular selectivity problem.
    Additional Material: 4 Ill.
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  • 9
    ISSN: 0887-3585
    Keywords: lectins ; crystal structure ; lectin specificity ; mannose ; glucose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The structure of the methyl-α-D-mannopyranoside-LOL I complex has been solved by the molecular replacement method using the refined saccharide-free LOL I coordinates as starting model. The methyl-α-D-mannopyranoside-LOL I complex was refined by simulated annealing using the program X-PLOR. The final R-factor value is 0.182 [Fo 〉 1σ(Fo)]. The isostructural methyl-α-D-glucopyranoside-LOL I complex was refined by X-Ray coupled energy minimization using the methyl-α-D-mannopyranoside-LOL I structure as a starting model to an R factor of 0.179 (all data). In both crystal forms, each dimer binds two molecules of sugar in pockets found near the calcium ions. The two saccharide moieties, which are in the C1 chair conformation, establish the same hydrogen bond pattern with the lectin. However, the van der Walls contacts are different between the O2, C2, C6, and O6 atoms of the two molecules and the backbone atoms of residues 208-211. Mannose, due to its axial C2 conformation, encloses the backbone atoms of the protein in a clamplike way. Van der Waals energy calculations suggest that this better complementarity of the mannoside molecule with the lectin could explain its higher affinity for isolectin I.
    Additional Material: 7 Ill.
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  • 10
    ISSN: 0887-3585
    Keywords: α/β-barrels ; protein structure ; loops ; molecular modeling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A systematic survey of seven parallel α/β barrel protein domains, based on exhaustive structural comparisons, reveals that a sizable proportion of the αβ loops in these proteins - 20 out of a total of 49 - belong to either one of two loop types previously described by Thornton and co-workers. Six loops are of the αβ1 type, with one residue between the α-helix and β-strand, and 13 are of the αβ3 type, with three residues between the helix and the strand. Protein fragments embedding the identified loops, and termed αβ connections since they contain parts of the flanking helix and strand, have been analyzed in detail revealing that each type of connection has a distinct set of conserved structural features. The orientation of the β-strand relative to the helix and loop portions is different owing to a very localized difference in backbone conformation. In αβ1 connections, the chain enters the β-strand via a residue adopting an extended conformation, while in αβ3 it does so via a residue in a near α-helical conformation. Other conserved structural features include distinct patterns of side chain orientation relative to the β-sheet surface and of main chain H-bonds in the loop and the β-strand moieties. Significant differences also occur in packing interactions of conserved hydrophobic residues situated in the last turn of the helix. Yet the α-helix surface of both types of connections adopts similar orientations relative to the barrel sheet surface. Our results suggest furthermore that conserved hydrophobic residues along the sequence of the connections, may be correlated more with specific patterns of interactions made with neighboring helices and sheet strands than with helix/strand packing within the connection itself. A number of intriguing observations are also made on the distribution of the identified αβ1 and αβ3 loops within the α/β-barrel motifs. They often occur adjacent to each other; αβ3 loops invariably involve even numbered β-strands, while αβ1 loops involve preferentially odd β-strands; all the analyzed proteins contain at least one αβ3 loop in the first half of the eightfold α/β barrel. Possible origins of all these observations, and their relevance to the stability and folding of parallel α/β barrel. Possible origins of all these observations, and their relevance to the stability and folding of parallel α/β barrel motifs are discussed.
    Additional Material: 6 Ill.
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