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  • Chemistry  (54)
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  • 1
    Electronic Resource
    Electronic Resource
    Adsorptive stripping voltammetric measurements of chromium accumulation in mice organs using mercury film microelectrodes (1997)
    Weinheim : Wiley-Blackwell
    Electroanalysis 9 (1997), S. 941-944 
    Details
    ISSN: 1040-0397
    Keywords: Chromium ; Microelectrodes ; Adsorptive stripping voltammetry ; Biomaterials ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chromium is the metallic species of most concern with the use of stainless steel implants. To study the distribution of chromium in mice organs with time, several animals were subcutaneously injected with 2.70 × 10-3 mol/L of chromium solution during a certain period of time. Square wave voltammetry using adsorptive collection of Cr3+ -DTPA complex on a mercury film microelectrode (MFM) was used for quantitation. Optimized conditions included DTPA concentration of 2.0 × 10-2 mol/L, sodium acetate 4.0 × 10-2 mol/L, sodium nitrate 0.40 mol/L, potassium permanganate 1.0 × 10-3 mol/L, pH ca. 6.1, deposition potential of -1.15 V, deposition time 20 s, frequency 100 Hz, step 2.5 mV and an amplitude of 20 mV. The detection limit of the method was 1.54 × 10-8 mol/L after deposition of 20s. Other species presented in the biological material such as calcium and iron do not interfere with the chromium determinations. The accuracy of the proposed method was checked by comparing the results with those obtained by atomic absorption spectrometry (AAS) yielding good agreement. The results showed an increase of chromium levels with time in liver, kidney and spleen, indicating that this metal is partially accumulated in the studied organs.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140091215
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  • 2
    Electronic Resource
    Electronic Resource
    Application of High Temperature High Resolution Gas Chromatography to Crude Extracts of Propolis (1998)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 396-400 
    Details
    ISSN: 0935-6304
    Keywords: high temperature gas chromatography ; flavonoids ; propolis ; high molecular weight compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The underivatized acetone and hexane fractions from propolis samples (predominant flora Citrus spp. and Vernonia polyanthes) were analyzed by HT-HRGC (high temperature high resolution gas chromatography) and HT-HRGC coupled to mass spectrometry (HT-HRGC-MS). Several compounds, including flavonoid aglycones, phenolic acids, and high molecular weight compounds were characterized in crude extracts by HT-HRGC-MS. HT-HRGC and HT-HRGC-MS were shown to be quick and informative tools for rapid analysis of crude extracts without need for prior derivatization and purification.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of nickel toxicity on liver, spleen, and kidney of mice after administration of high-dose metal ion (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 40 (1998), S. 40-47 
    Details
    ISSN: 0021-9304
    Keywords: nickel ; biomaterial ; mice ; microelectrodes ; histology ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The toxic effects caused by nickel (Ni) per si were explored by performing in vivo studies on mice following subcutaneous administration of a metallic solution of nickel at 1, 2, 3, and 4 weeks to evaluate the side effects of this metal ion when released from stainless steel implants. Other groups were similarly injected with HBSS and used as controls. Accumulation of Ni ions on liver, spleen, and kidney was assessed by an electrochemical method, adsorptive stripping voltammetry (AdSV) using microelectrodes, and atomic absorption spectrometry (AAS). Alterations of those organs induced by Ni ions were studied, showing that several histological changes had been induced. Chemical analysis and histological features indicate that Ni is partially accumulated in the study organs. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 40-47, 1998.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Metal ion sorption ability of poly(4-vinylpyridine-co-N,N-dimethylacrylamide) (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 230 (1995), S. 89-98 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch radikalische Polymerisation wurden Harze mit Amid- und 4-Vinylpyridin-Gruppen synthetisiert. Die hergestellten wasserunlöslichen Polymeren Poly(4-vinylpyridin) (1), Poly(4-vinylpyridin-co-N,N-dimethylacrylamid) (2) und Poly(N,N-dimethylacrylamid) (3) wurden mit FT-IR-Spektroskopie, Elementaranalyse und Thermoanalyse charakterisiert. Die Fähigkeit der Harze, Cu(II)-, Fe(II)-, Fe(III)- und U(VI)-Ionen zu binden, wurde mit der Batch-Gleichgewichts-Methode bei verschiedenen pH-Werten untersucht. Die Harze 1 und 2 adsorbierten bei pH 1 mehr als 50% U(VI). Die Selektivität von U(VI) gegenüber Cu(II) bei pH 1,0 betrug 2,11. Durch Behandlung mit Schwefelsäure und Natriumcarbonat konnte das mit Uran beladene Polymere 2 teilweise regeneriert werden.
    Notes: Resins containing amide and 4-vinylpyridine moieties were synthesized by radical polymerization. All the resins were completely insoluble in water and characterized by FT-IR spectroscopy, elemental analysis and thermal analyses. The ability to bind Cu(II), Fe(II), Fe(III) and U(VI) ions at different pHs was studied by batch equilibrium procedure. Uranium(VI) was adsorbed at pH 1 above 50% by the resins 1 and 2. The selectivity of uranium(VI) respect to copper(II) at pH 1.0 was 2.11. The uraniumloaded resin 2 could be partially recovered by treatment with H2SO4 and Na2CO3.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052300105
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  • 5
    Electronic Resource
    Electronic Resource
    Minor Coumarins from Calophyllum teysmannii var. inophylloide and Synthesis of Cytotoxic Calanone Derivatives (1998)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 1404-1416 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Chemotaxonomic survey for biologically active compounds from Malaysian Calophyllum species led to the findings of the four new benzoylcoumarins 1a, 2, 3, and 4a (including the unusual prenylated 6-benzoylcoumann 1a), two uncommon coumarins 5 and 6a with a pyran-4-one moiety fused at C(6) and C(7), and compounds 7a, 9, and 10, all isolated from the bark of C. teysmannii var. inophylloide. Their structures were determined by spectroscopic analysis and chemical transformations. X-Ray crystal-structure determination of 2 provided information on the conformational preferences of substituents in this class of coumarins. The syntheses of the cytotoxic calanone (7a) and of some related coumarins are described.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19980810549
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  • 6
    Electronic Resource
    Electronic Resource
    Über herzwirksame Glykoside und Aglykone der Samen von Coronilla glauca. 21. Mitteilung über Herzglykoside (1949)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 32 (1949), S. 293-315 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coronilla glauca enthält ein kompliziertes Gemisch von Herzglykosiden, die sich aus verschiedenen Geninen und Glucose aufbauen. Bei der Einwirkung eines spezifischen Samenenzyms wird die Zucker-Aglykon-Bindung gelöst. Es ist unseres Wissens damit zum ersten Male ein spezifisches herzglykosidspaltendes Enzym, das sein Substrat bis zum Aglykon abbaut, bekannt geworden.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19490320141
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  • 7
    Electronic Resource
    Electronic Resource
    Identification and control of oxidative metabolism in Saccharomyces cerevisiae during transient growth using calorimetric measurements (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 610-619 
    Details
    ISSN: 0006-3592
    Keywords: dynamic model ; Saccharomyces cerevisiae ; oxidative capacity ; feedback control ; calorimetry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The objective of this study was to characterize the dynamic adaptation of the oxidative capacity of Saccharomyces cerevisiae to an increase in the glucose supply rate and its implications for the control of a continuous culture designed to produce biomass without allowing glucose to be diverted into the reductive metabolism. Continuous cultures subjected to a sudden shift-up in the dilution rate showed that the glucose uptake rate increased immediately to the new feeding rate but that the oxygen consumption could not follow fast enough to ensure a completely oxidative metabolism. Thus, part of the glucose assimilated was degraded by the reductive metabolism, resulting in a temporary decrease of biomass concentration, even if the final dilution rate was below Dcrit. The dynamic increase of the specific oxygen consumption rate, qO2, was characterized by an initial immediate jump followed by a first-order increase to the maximum value. It could be modeled using three parameters denoted qjumpO2, qmaxO2, and a time constant τ. The values for the first two of the parameters varied considerably from one shift to another, even when they were performed under identical conditions. On the basis of this model, a time-dependent feed flow rate function was derived that should permit an increase in the dilution rate from one value to another without provoking the appearance of reductive metabolism. The idea was to increase the glucose supply in parallel with the dynamic increase of the oxidative capacity of the culture, so that all of the assimilated glucose could always be oxidized. Nevertheless, corresponding feed-profile experiments showed that deviations in the reductive metabolism could not be completely suppressed due to variability in the model parameters. Therefore, a proportional feedback controller using heat evolution rate measurements was implemented. Calorimetry provides an excellent and rapid estimate of the metabolic activity. Satisfactory control was achieved and led to constant biomass yields. Ethanol accumulated only up to 0.49 g L-1 as compared to an accumulation of 1.82 g L-1 without on-line control in the shift-up experiment to the same final dilution rate. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 610-619, 1998.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of chlorinated organic compounds in estuarine biota and sediments by chemical ionization tandem mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 464-470 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complex sample matrices of estuarine biota tissue and bed sediment extracts were analyzed for selected chlorinated compounds. By using gas chromatography/positive chemical ionization/tandem mass spectrometry, the coeluting interferences present in gas chromatography/electron ionization mass spectrometry were eliminated in the biota tissue and bed sediment extracts. The selected chlorinated compounds included chlorobenzene; 1,2-, 1,3- and 1,4-dichlorobenzene; 1,2,3-, 1,2,4- and 1,3,5-trichlorobenzene; 1,2,3,4-, 1,2,3,5- and 1,2,4,5-tetrachlorobenzene; pentachlorobenzene; hexachlorobenzene; hexachloro-1,3-butadiene; octachlorostyrene; and octachloronaphthalene. Daughter ion spectra for these compounds are included. The detection limit for most of the compounds was 20 pg, and the instrument response was linear over five orders of magnitude, by using 13C-labelled hexachlorobenzene as the internal standard.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200180704
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of herbicides and their degradation products in surface waters by gas chromatography/positive chemical ionization/tandem mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 820-827 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A rapid, sensitive and specific method was developed for the analysis of selected herbicides and their degradation products in surface water samples using gas chromatography/positive chemical ionization/tandem mass spectrometry (GC/PCI/MS/MS). Compounds included atrazine and its degradation products (deethylatrazine and deisopropylatrazine), simazine, alachlor and its degradation products (2-chloro-2′,6′-diethylacetanilide, 2-hydroxy-2′,6′-diethylacetanilide and 2,6-diethylaniline) and metolachlor. Daughter ion spectra for the protonated molecule of these compounds were generated and are described. The coeluting interferences present using GC/electron impact mass spectrometry in the surface water samples were eliminated by using GC/PCI/MS/MS in the neutral loss mode to detect specific daughter ions. The detection limit for most of the compounds was 200 pg, and instrument response was linear over three orders of magnitude.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200180928
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  • 10
    Electronic Resource
    Electronic Resource
    Immobilization of glucose oxidase on nylon membranes and its application in a flow-through glucose reactor (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 275-279 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The immobilization of glucose oxidase on hydrolyzed nylon-6,6 was studied. Various spacers were introduced on the support before the coupling of the enzyme. Best results were obtained when the membrane was covered with denatured bovine serum albumin (BSA) before spacer coupling and immobilization of glucose oxidase (GOD). The influence of various factors (pH, ionic strength, etc.) on the activity of the free and immobilized enzyme was investigated. It was found that the behavior of the fixed glucose oxidase and the free enzyme is very similar. The covalently immobilized enzyme had a lifetime of around 2 months (50% of initial activity).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080290216
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