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  • Digitale Medien  (228)
  • AV-Medium
  • Loseblatt
  • 1995-1999  (228)
  • 1997  (228)
  • Industrial Chemistry and Chemical Engineering  (228)
Materialart
  • Digitale Medien  (228)
  • AV-Medium
  • Loseblatt
Erscheinungszeitraum
  • 1995-1999  (228)
Jahr
  • 101
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 533-537 
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Airlift loop reactors are useful in many chemical and biotechnological processes where three phase reaction systems are required. One example is biological waste water treatment. In order to enhance biological reaction rates it is often useful to immobilize the bacteria on carrier particles. Knowledge of solid distribution and local gas holdup in those systems is important for calculation of mass and energy transfer or reaction kinetics. For this reason a method has been developed which enables to measure such local phase holdups. The measuring system consists of a time-domain-reflectometry (TDR)-instrument in combination with a pressure difference meter. The method has successfully been applied to determine local axial gas and solid distribution in internal airlift loop reactors, filled with a three phase system consisting of water, air, and polymer particles.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 102
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 538-549 
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: New data of gas-liquid mass transfer for cocurrent downflow through packed beds of porous and non-porous particles are presented. Mass transfer parameters for air/carbon dioxide/water, air/carbon dioxide/carboxymethylcellulose solution and air/carbon dioxide/sodium hydroxide systems were evaluated by least square fit of the calculated CO2 concentration profiles in gas phase to the experimental values. The volumetric liquid-side mass transfer coefficient increases with the increase of the flow consistency index of the liquid. A comparison of the volumetric liquid-side mass transfer coefficient values evaluated with and without taking into account the axial dispersion shows that the influence of the liquid axial dispersion is significant at low liquid velocity and high CMC concentrations, and the influence of the gas axial dispersion is insignificant.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 103
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997) 
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 104
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 304-308 
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The radial solids fraction profiles in the inlet region of a high density circulating fluidized bed (HDCFB) are studied by a dual-beam optic density sensor. Three kinds of inlet structures are employed to examine the axial developing process of the profiles. The acceleration effect of solids is analyzed by comparing the cross-sectional average solids fraction obtained by the density sensor and differential pressure method. The results show that the radial solids fraction profile is largely influenced by the inlet structure. The length for the inlet effect region is no more than 1.5 m above the air injection.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 105
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 317-325 
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The detailed knowledge of the soot distribution is an indispensible prerequisite for a study of the impact of fluid dynamics on the regeneration behaviour of ceramic fiber coil filters. As shown by experiments and simulation calculations the soot distribution can be reliably predicted with a mathematical model formulated in terms of the structural parameters as well as of the operating conditions. Furthermore, it is demonstrated that besides its effect on the regeneration behaviour the impact of fluid dynamics on the soot distribution must be considered, too.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 106
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 342-347 
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Two types of solid adsorbents, activated carbon and zeolite 13X, were used at 80°C to remove sulfur compounds from naphtha solutions. Adsorption isotherms have been determined in a pressure vessel. This investigation indicated that activated carbon is superior to zeolite 13X at such high temperatures. A new formula based on the Langmuir model has been found to fit the experimental data satisfactorily. Comparison of the findings of this study with those of a previous one conducted at ambient temperatures in this department indicates that such treatment generally gives better results at low temperature where almost complete recovery of the sulfur compounds can be performed by using zeolite 13X.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 107
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 596-605 
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The objective of the work presented here was the development of a method of modeling the effect of an impeller on the velocity distribution in a stirred vessel. The developed model makes it possible to numerically investigate the flow field almost independently of any experimental data. The starting point was a force balance around an impeller blade, which took into consideration the lift and drag forces. The obtained volume forces were circumferentially averaged in the impeller region. The calculations were carried out time-averaged for the case of a pitched blade impeller. The results were compared with experimental data which were obtained by laser Doppler anemometry. The comparison of the axial velocity components shows a good agreement between numerical and experimental data. Furthermore some characteristic integral values were calculated, which demonstrate the efficiency of the impeller.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 108
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 20 (1997), S. 612-616 
    ISSN: 0930-7516
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The instability of a falling film under high pressure (droplet formation) was characterized by the dimensionless Reynolds, Weber, and fluid-film numbers and could be predicted in a characteristic diagram. Incipient droplet formation was achieved with the given material properties of the system, i.e., at a constant KF number, by increasing the volumetric flowrate of the liquid phase.The investigations were performed with the material systems α-tocopherol/CO2 and squalane/CO2 in the pressure ranges between 8 and 35 MPa and 6 and 12 MPa, respectively, at four different temperatures between 313 and 353 K. The volumetric flowrate of the liquid phase was varied between 10 and 300 ml/min, whereas the speed of the supercritical gas phase in counter-current flow to the falling film in the falling-film cell was kept constant at 7 mm/s. The high-pressure falling-film cell used for this purpose had an external diameter of 104 mm, an internal diameter of 34 mm, and a total length of 710 mm. The diameter and length of the cylindrical falling-film carrier were 10 and 500 mm, respectively.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 109
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 14 (1997) 
    ISSN: 0934-0866
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 110
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 14 (1997), S. 272-277 
    ISSN: 0934-0866
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Two descriptors based on mathematical morphology are described which permit discrimination between convex and concave polygonal shapes which often characterize crystalline particles. Their computation is based on the comparison between the silhouette of the particle and a reference shape. Three reference shapes are discussed: the convex hull, the circle circumscribed to the particle and the equivalent circle.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 111
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 14 (1997), S. 267-271 
    ISSN: 0934-0866
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A method called “image-sedimentation”, based on the application of Stokes' law to suspension and image techniques, is proposed for the rapid analysis of particle size distributions. A parallel beam of optical light, after passing through a cell containing particles, is measured with a linear image sensor with 2048 photodetectors to determine the attenuated light intensity displayed on a monitor screen. The settling height between any given point and the liquid surface can be measured accurately by use of this image technique without any additional mechanical device to move either the light beam or the glass cell containing the suspension. Consequently, the total time required for the determination of the particle size distribution, typically of a carborundum powder having a median diameter of 5 μm, takes only 5 min as compared with more than 20 min by using other instruments based on the sedimentation principle.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 112
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 14 (1997), S. 278-282 
    ISSN: 0934-0866
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In previous work, the relative performance of various methods used to characterize the particle size distribution of powders composed of fine irregularly shaped particles was assessed. It was found that methods employing Fraunhofer diffraction theory were inferior with respect to particle counting methods. Furthermore, calculated particle size distributions varied considerably between manufactures of Fraunhofer devices. It is well known that the Mie optical model can also be used to analyze the data collected by laser diffraction instruments. Here, we have compared particle size distributions collected using two Laser diffraction instruments to those determined by the Aerosizer. In our earlier work the Aerosizer was shown to produce results nearly identical to those determined by image analysis. The results of this study indicate that the use of the Mie optical model does not correct for deficiencies previously noted for laser diffraction methods. Considerable variation exists between the results obtained on laser diffraction instruments manufactured by different companies. Our earlier recommendation to use extreme caution when employing laser diffraction instruments to characterize fine powders continues to be supported in the present work.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 113
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 756-756 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 114
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 737-741 
    ISSN: 0268-2605
    Schlagwort(e): organotin speciation ; pulsed flame photometric detection ; capillary gas chromatography ; environmental samples ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Pulsed flame photometric detection (PFPD) for gas chromatography was applied to organotin compounds as standards and in environmental samples. Ethylated organotin species (n-propyl-, n-butyl- and phenyl-) were extracted from spiked artificial seawater and from an environmental sample. Selectivity towards tin is shown in the analysis of highly polluted seawater samples from a commercial port where no significant interferences are found. The self-cleaning capability and long-term stability of PFPD is shown in this work during 140 days of continuous operation. The absolute limit of detection for this capillary GC-PFPD technique ranged from 0.2 to 0.4 pg (Sn) for tetraethyl- to tetraphenyl-tin, allowing determination of sub-nanogram/litre concentrations of organotin compounds. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 115
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 539-539 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 116
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 540-540 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 117
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 491-497 
    ISSN: 0268-2605
    Schlagwort(e): palladium ; complexes ; imidazole ; cyclometalation ; DNA ; intercalation ; drug ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In this paper, we show the synthesis of palladium(II) 4,5-phenylimidazole cyclometalated complexes. They have been characterized by IR, 1H- and 13C-NMR spectroscopy. The cyclometalated dimer compound 2 [Pd(C15H11N2)(μ-OAc)]2 and the cyclometalated monomer compound 5 [PdBr(SEt2)(C15H11N2)], having OAc and Br as leaving groups, interact with DNA, modifying its secondary structure (as measured by Tm and CD), without modifying its tertiary structure (as determined by measurement of the electrophoretic mobility in agarose gels). The monomeric compound 5 seems to be the one that induces the highest alterations in DNA secondary structure since it strongly modifies the CD spectrum of the DNA. Melting data of drug-DNA complexes suggest that, at low drug concentration, the 4,5-Imd ligand intercalates between the base pairs in the DNA molecule, increasing the Tm, while at high drug concentrations the palladium(II) centers destabilize the double helix, producing a lowering in Tm values. These results indicate that complexes containing planar structures might selectively bind to DNA that is not supercoiled, and that therefore it only has a secondary structure. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 118
    ISSN: 0268-2605
    Schlagwort(e): organotin ; porphyrin ; structures ; Mössbauer ; infrared ; NMR ; biologial activity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis, the structural features and the in vivo biological activity of diorganotin(IV) and triorganotin(IV) derivatives of [meso-tetra(4-carboxyphenyl)porphine] (H4TPPC) are reported. Derivatives with general formula (R2Sn)2TPPC and (R3Sn)4TPPC (R=Me, Bu, and Ph) were obtained, and the main information extracted from the infrared and Mössbauer spectral data, in the solid state, was in favor of the occurrence of five-coordinated tin(IV) atoms, in a polymeric trigonal-bipyramidal configuration, attained through two differently coordinated, ester-type and chelating respectively, carboxylate anions in [R2Sn]2TPPC, while in [Alk3Sn]4TPPC five-coordination of the tin(IV) atom is reached through bridging carboxylate groups.1H and 13C NMR spectra, in DMSO-d6 or CDCl3 suggested that the soluble derivatives, at room temperature or at 342 K, were present in solution as simple monomers.The interactions of (trimethyltin)4[meso-tetra(4-carboxyphenyl)porphinate] (TMTPPC) and (tributyltin)4[meso-tetra(4-carboxyphenyl)porphinate] (TBTPPC) with Bluescript KS(+) plasmid and cultured 3T3 fibroblasts were studied.Both compounds have a clear inhibitory effect on the growth of cultured mouse embryonal fibroblasts (NIH-3T3), TBTPPC being much more active. No evidence was found, however, for DNA cleavage by the compounds at molar ratios as high as 1:10 (TMTPPC, TBTPPC/DNA base pairs).According to our observations, the cytotoxicity of TBTPPC and TMTPPC does not seem to be based on direct interaction with DNA. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 119
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 565-575 
    ISSN: 0268-2605
    Schlagwort(e): complexes of furan oximes ; IMP dehydrogenase ; purine inhibitors ; cytotoxicity ; nucleic acid inhibitors ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The copper complexes of furan oxime derivatives were found to be potent cytotoxic agents in both murine and human tissue cultured cell lines which were suspended as well as solid tumors. Mode of action studies in murine L1210 lymphoid leukemia cells showed that the compounds suppressed DNA, RNA and protein synthesis after 60 min at 100 μM. Inhibition of purine and pyrimidine de novo syntheses, as well as inhibition of ribonucleoside reductase and nucleoside kinase activities with DNA strand scission occurred. All of these effects of the drug probably added to its ability to cause cell death but most important was the inhibition of DNA topoisomerase II activity with IC50 values lower than those afforded by VP-16, the standard, which should cause apoptosis. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 120
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 591-600 
    ISSN: 0268-2605
    Schlagwort(e): organotin compounds ; lecithin liposome membrane ; Ca2+ and Pr3+ desorption ; 1H NMR ; radioactive tracer methods ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organometallic compounds and surfactants constitute a potential threat to the environment. For that reason we have embarked on a study of their joint action on membranes. Model lecithin liposome membranes were modified with the cationic surfactant trimethyldodecylammonium bromide or the anionic surfactant sodium dodecylsulfonate, and the effect of tripropyltin chloride on the process of calcium (Ca2+) and praseodymium (Pr3+) desorption from the liposome membrane was studied.Kinetic constants for the process of Ca2+ ion desorption from lecithin liposome membranes were determined using the radiotracer method. The percentage of Pr3+ ion desorption from liposome membranes was measured by the 1H NMR method.Trimethyltin, triethyltin and tripropyltin alone caused increased Ca2+ and Pr3+ desorption from liposome membranes with increasing concentration of the compounds and alkyl chain length. For both the processes studied, a cationic surfactant brought about a lower effectiveness of tripropyltin and an anionic surfactant resulted in a higher effectiveness.The effect observed can be explained by changes in the surface charge of the membrane, induced by the surfactant modifiers and by the concomitant change in the partition coefficient of the organotin. The results obtained indicate a protective or harmful joint action of the surfactants used with tripropyltin on membranes. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 121
    ISSN: 0268-2605
    Schlagwort(e): triorganotin(IV) ; L-homocysteic acid ; infrared ; Mössbauer ; NMR ; sea urchin ; Paracentrotus lividus (Echinodermata) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Several new triorganotin(IV) derivatives of L-homocysteic acid (L-HCAH) with formula R3Sn(L-HCA) (R=Me, nBu, Ph) have been synthesized. Their solid-state configurations were determined by IR and Mössbauer spectroscopy. The tin(IV) atom is five-coordinated in all the complexes, with the L-homocysteic acid behaving as a monoanionic bidentate ligand coordinating the tin(IV) atom through a chelating or bridging carboxylate group. The sulfonate (SO3-) and NH3+ groups of L-homocysteic acid maintain their free acid configuration and hence do not participate to the coordination of the tin(IV) atom. Coordination hypotheses have been checked through the correlation between the Mössbauer parameter isomer shift, δ, and partial atomic charge on the tin atoms, QSn, performed, for all the new organotin(IV) compounds, on the basis of an equalization procedure applied to idealized trigonal-bipyramidal structures for R3Sn(L-HCA).1H and 13C NMR spectra of the complexes show that pentacoordination of the tin atom, with R groups in the equatorial plane of a trigonal bipyramid, is retained in DMSO solution. The NMR data confirm also that the uncoordinated NH3+ group of the ligand is still present in solution.Results gathered after exposure of two- to four-cell embryos of the sea urchin Paracentrotus lividus (Echinodermata) to the triorganotin(IV) L-homocysteate derivatives as well as to the parent triorganotin(IV) chlorides document cytotoxicity of the complexes, while free L-homocysteic acid exerts no significant toxic activity. The trimethyltin(IV) L-homocysteate derivative seems to exert a lower cytotoxicity than the tributyl- and triphenyl-tin(IV) ones. Different structural lesions have been identified by comparative analysis of mitotic chromosomes from untreated embryos (negative controls) and embryos treated with triorganotin(IV) L-homocysteate derivatives, such as (1) suppression of the stretch among sister chromatids at the beginning of anaphase stage; (2) deeply stained zones mainly located at the telomeric regions of chromosomes; (3) arm breakages; and (4) chromosome bridges among daughter chromosomes at anaphase stage. A colchicine-like effect of triorganotin(IV) L-homocysteate derivatives was observed. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 20 Ill.
    Materialart: Digitale Medien
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  • 122
    ISSN: 0268-2605
    Schlagwort(e): palladium ; platinum ; imidazoline ; DNA ; cyclometallated complexes ; cytotoxic activity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In this paper we describe the synthesis and chemical characterization of three new Pd(II)-imidazoline complexes: [PdCl2 (C6H5-CH2-C3H5N2)2] (2), [PdCl(SEt2) (C6H4-C3H5N2)] (5) and [Pd(C6H4-C3H5N2) (μ-Br)]2 (6). We have also analyzed the DNA modifications and in vitro antileukaemic activity of these compounds and of their previously reported analogs [Pd Cl2 (C6H5-C3H5N2)2] (1), [Pd (C6H4-C3H5N2) (μ-OAc)]2 (3), [Pd (C6H4-C3H5N2) (μ-Cl)]2 (4) and [Pt(C6H4-C3H5N2)(μ-Cl] (7). All these compounds modify the DNA secondary structure since they alter the melting temperature (Tm) of the DNA. Circular dichroism spectra indicated, moreover, that compounds 3, 5 and 6 induced higher modification on the double helix than compounds 1, 2 and 4. While compounds 1, 2 and 5 seem to induce slight changes in the electrophoretic mobility of the open and covalently closed circular forms of pUC8 DNA at high ri (input molar ratio of Pd or Pt to nucleotides), compounds 3, 6 and 7 do not modify at any ri the tertiary structure of the plasmid DNA. Antileukaemic tests suggest that compounds 1, 4 and 7 exhibit important cytotoxic activity since their IC50 values against HL-60 human leukaemic cells were below 10 μg ml-1. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 123
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 705-705 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 124
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 543-550 
    ISSN: 0268-2605
    Schlagwort(e): tributyltin ; passive adsorption ; facilitated absorption ; uptake mechanism ; phytoplankton ; surface cells ; toxic effects ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The sorption of tributyltin (TBT) by phytoplankton cells was studied by exposing the marine microflagellated alga Pavlova lutheri grown in batch culture to TBT chloride concentrations ranging from 0.37 to 74 nM (0.1 to 21 μg l-1) for a 24-hour period. The phytotoxicity of TBT was indicated by a decrease in cell density at all TBT concentrations used. TBT was tightly bound to the surface cell and was only washed out by a strong acidic solution (pH≤3) while inner cell-absorbed TBT was only recovered by means of an organic solvent. The sorption of TBT by P. lutheri occurred via two mechanisms: a passive ionic surface adsorption followed by a facilitated intracellular absorption. The coupling/uncoupling of these two mechanisms was dependent upon the contamination level used. The cell surface adsorption of TBT was best described by the Freundlich adsorption model whereas the obstruction of the facilitated absorption mechanism was apparently related to the toxic activity of TBT towards cell components. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
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  • 125
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 126
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 633-633 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 127
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 706-706 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 128
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 693-702 
    ISSN: 0268-2605
    Schlagwort(e): organotin ; Grignard reagents ; sodium tetraethylborate ; mussels ; derivatization ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two different derivatization methods, alkylation with Grignard reagents, and ethylation with sodium tetraethylborate, were compared for the determination of organotin compounds, viz. tributyltin, dibutyltin, monobutyltin, triphenyltin, diphenyltin and monophenyltin, in mussel samples. Temperature, reaction time and concentration of Grignard reagents were optimized in the former method; in the latter the effect of pH, concentration of sodium tetraethylborate and reaction time were studied. In the derivatization with Grignard reagents hexyl, pentyl, propyl, ethyl and methyl were used as alkyl Grignard groups. A critical evaluation of the different derivatization methods is presented. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 6 Ill.
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  • 129
    ISSN: 0268-2605
    Schlagwort(e): organotin(IV) ; Schiff base ; amino-acid ; antimicrobial activity ; antitumour activity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Equimolar reactions of dibutyltin(IV) oxide with Schiff bases derived from amino-acids led to the formation of a new series of dibutyltin(IV) complexes of general formula, Bu2SnL [L=dianion of tridentate Schiff bases derived from the condensation of 2-hydroxy-1-naphthaldehyde or acetyl acetone with glycine (L-1), L-β-alanine (L-2), DL-valine (L-3), DL-4-aminobutyric acid (L-4), L-methionine (L-5), L-leucine (L-6) and phenylglycine (L-7)]. An attempt has been made to prove the structures of the resulting complexes on the basis of elemental analyses, conductance measurements and electronic, IR, multinuclear magnetic resonance (1H, 13C and 117Sn) and 119Sn Mössbauer spectral studies. The complexes have been tested against various bacteria [Streptococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus penicillin resistance (2500 units)] and fungi (Candida albicans, Cryptococcus neoformans, Sporotrichum schenckii,Trichophyton mentagrophytes and Aspergillus fumigatus). All the complexes showed moderate activity. The cytotoxicity of a few compounds has been screened in vitro against seven human tumour cell lines, viz. MCF-7, EVSA-T, WiDr, IGROV, M19 MEL, A498 and H226. The activities found experimentally were better than those obtained for cisplatin and carboplatin © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Ill.
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  • 130
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 743-749 
    ISSN: 0268-2605
    Schlagwort(e): methylarsonic acid ; dimethylarsinic acid ; trimethylarsine oxide ; mitotic arrest ; aneuploidy ; c-mitosis ; tetraploidy ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Inorganic arsenic is methylated in the mammalian body to methylarsonic acid (MMA), dimethylarsinic acid (DMA) and trimethylarsine oxide (TMA). To achieve a more precise understanding of arsenic carcinogenicity, we examined the genotoxic effects of organic arsenic compounds on human lymphocytes by assessing induction of mitotic arrest, sister chromatid exchange (SCE) and aneuploidy. MMA, DMA and TMA arrested mitosis, DMA induced hyperdiploid cells, and DMA and TMA induced tetraploid cells. Of the three arsenic metabolites tested, DMA had the strongest effects on cell mitosis and aneuploidy induction. DMA arrested mitosis and induced c-mitosis significantly. These results suggest that DMA arrests mitosis and induces aneuploidy through spindle disruptions similar to those observed with known spindle poisons, such as colchicine or vinblastine. Since aneuploidy has been thought to be associated with tumor induction or neoplastic transformation, induction of aneuploidy by organic metabolites of arsenic may play a major role in arsenic carcinogenesis in humans. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 131
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 57-66 
    ISSN: 0268-2605
    Schlagwort(e): Chlorella sp. ; biomethylation ; arsenic ; HPLC-ICP-MS ; cadmium ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The growth of Chlorella Böhm, Chlorella kessleri and Chlorella 108 in media containing sodium arsenate at 200 or 2000 mg As dm-3 was investigated. The cell densities in the stationary phases were 40% higher for Chlorella Böhm (5.6×105 cells cm-3) and Chlorella kessleri (4.5×105 cells cm-3) grown in the 2000 mg As dm-3 arsenate media compared with the arsenic-free media. The growth of Chlorella 108 was depressed by arsenate. Dimethylarsinic acid (at concentrations never exceeding 1.2 mg As dm-3) and arsenite (≲0.2 mg As dm-3) were detected in the growth medium. The cells harvested during the stationary phase had 2400 mg arsenic associated with 1 kg dry mass. A water/methanol (80:20) mixture extracted all the arsenic from the cells. Most of the arsenic (99%) was arsenate. Arsenite, methylarsonic acid and dimethylarsinic acid accounted for the remaining arsenic. Cadmium in the arsenic-containing growth media (50 μg to 100 mg dm-3) reduced the yield of algal cells and induced the formation of an unidentified arsenic compound in Chlorella Böhm. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
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  • 132
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 147-151 
    ISSN: 0268-2605
    Schlagwort(e): chemical vapor deposition ; tin(IV) oxide ; films ; di(n-butyl)tin ; photolysis ; dopant ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A laser-assisted chemical vapor deposition scheme for SnO2 films has been developed, based on the UV multiphoton dissociation of di (n-butyl) tin diacetate. Doped films were produced by simultaneous photolysis of other inorganic precursors. Films were characterized by UV-visible spectroscopy, room-temperature resistance measurements in the presence of a variety of gas-phase contaminants, and the temperature dependence of film resistance. These preliminary investigations demonstrate the ability to vary detection sensitivity and selectivity by changing the dopant precursor identity. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
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  • 133
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 163-179 
    ISSN: 0268-2605
    Schlagwort(e): sol-gel ; ceramics ; glasses ; films ; organometallic ; titanium ; niobium ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The advent of the sol-gel technique over the past several decades and the recognition of its excellent flexibility for synthesizing a large variety of oxide ceramics and glasses in both bulk and thin-film forms has generated considerable interest in using solution-based processes to prepare ceramic materials. Because of the success of the sol-gel technique, a number of other chemical processes have been developed utilizing metalorganic/organometallic starting materials to create molecularly architectured precursors, which have proven effective in synthesizing both oxide and non-oxide materials. In the present study, two different chemical approaches have been implemented to synthesize non-oxides (sulfides and nitrides) of reactive transition-metal elements. Accordingly, a novel thio-sol-gel process for preparing TiS2 and NbS2 powders has been studied. In the case of TiS2 synthesis, the chemical reaction has been examined in detail using Fourier-transform infrared spectroscopy (FTIR) and gas chromatography (GC). The effects of modification of the titanium precursor on the morphology of the final sulfide have also been investigated and are discussed. A second, more generalized process has been developed for synthesizing homogeneous precursors in multicomponent systems. Its utilization in preparing ternary nitrides has been demonstrated, and is also presented. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 9 Ill.
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  • 134
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 69-69 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 135
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 181-194 
    ISSN: 0268-2605
    Schlagwort(e): synthesis ; silazanes ; polymer pyrolysis ; non-oxide ceramics ; Si3N4 ; SiC ; crystallization ; ceramic matrix composites ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The goal of this investigation was to optimize the synthesis of silazane-based polymers for processing fibre-reinforced ceramic matrix composites (CMCs). Liquid oligomeric silazanes were synthesized by ammonolysis of chlorosilanes and characterized spectroscopi- cally (FTIR, NMR) as well as by elemental analysis. The silazanes were obtained in high yield and purity. Different functional groups (system S1: Si - H, Si - CH3, Si - CH=CH2) and different degrees of branching in the Si - N backbone [system S2; Si(NH)3, Si(NH)2] were realized in order to study the properties of the silazanes that are dependent on the molecular structure.For processing ceramics via pyrolysis of pre-ceramic oligomers, molecular weight, rheological behaviour, thermosetting and ceramic yield were investigated systematically and correlated with the molecular structure of the silazanes. Low molecular weights (500-1000 g mol-1) as well as low viscosity values (0.1-20 Pa s) enable processing of the silazanes in the liquid phase without any solvent. Due to the latent reactivity of the functional groups, curing of the polymers via hydrosilylation is achieved.Structural changes and weight loss during polymer curing as well as the organic/inorganic transition were monitored by FTIR spectroscopy and differential thermogravimetric analysis. With increasing temperature (room temperature to 800 °C) the hydrogen content decreases from 7 to 〈 0.5 wt% due to the formation of gaseous molecules (NH3, CH4, H2). High ceramic yields up to 80% were reached by branching the oligomers, thus reducing the amount of volatile precursor fragments.Up to 1300 °C, ceramic materials remained amorphous to X-rays. At higher temperatures (1400-1800 °C) either SiC or SiC/Si3N4 composites were selectively crystallized, depending on the pyrolysis conditions. The utility of the optimized precursors for CMCs has been demonstrated by infiltration of fibre preforms and subsequent pyrolysis. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 13 Ill.
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  • 136
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 297-304 
    ISSN: 0268-2605
    Schlagwort(e): freshwater biota ; freshwater fish ; freshwater algae ; organic arsenic ; arsenic ; arsenobetaine ; arsenosugar ; dimethylarsenic ; trimethylarsenic ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Arsenic circulation in an arsenic-rich freshwater ecosystem was elucidated to detect arsenic species in the river water and in biological samples living in the freshwater environment. Water-soluble arsenic compounds in biological samples were extracted with 70% methanol. Samples containing arsenic compounds in the extracts were treated with 2 mol dm3 of sodium hydroxide and reduced with sodium borohydride. The detection of arsenic species was accomplished using a hydride generation/cold trap/cryofocus/gas chromatography-mass spectrometry (HG/CT/CF/GC-MS) system. The major arsenic species in the river water, freshwater algae and fish are inorganic arsenic, dimethylarsenic and trimethylarsenic compounds, respectively. Trimethylarsenic compounds are also detected in aquatic macro-invertebrates. The freshwater unicellular alga Chlorella vulgaris, in a growth medium containing arsenate, accumulated arsenic and converted it to a dimethylarsenic compound. The water flea Daphnia magna, which was fed on arsenic-containing algae, converted it to a trimethylarsenic species. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 137
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 337-343 
    ISSN: 0268-2605
    Schlagwort(e): organosilane ; α-alkyl-α-aminosilane ; metalation ; hydrosilylation ; rearrangement ; Brook ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The readily available aminomethylsilanes can be utilized to prepare the less available α-alkyl-α-aminosilanes. Versatile t-butoxy-carbonal (Boc) derivatives can be metalated between nitrogen and silicon, and then alkylated by an electrophile at this position. Two alternative procedures were also developed, including an aza-reverse-Brook rearrangement of metalated N-silylcarbamates and hydrosilylation of N-alkenylcarbamates. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
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  • 138
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 458-458 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 139
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 397-402 
    ISSN: 0268-2605
    Schlagwort(e): arsenic ; arsenate ; arsenite ; cacodylic acid ; NO production ; DNA ; cellular proliferation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Exposure to arsenic, either through chronic consumption of contaminated water or inhalation, is associated with increased risk of cancer, yet the mechanism by which arsenicals promote neoplastic change remains undefined. The carcinogenic process involves the formation of heritable genetic changes in the DNA of normal cells and this process may be enhanced by environmental agents that increase cellular proliferation, increase DNA damage and decrease the ability to repair damage or cause immunosuppression. We describe the inhibition of cellular proliferation of C3H 10T1/2 murine fibroblasts in the presence of 1.0 μM arsenate or arsenite; yet cacodylic acid had no significant effect on cell growth in culture at this concentration. Both arsenate and cacodylate, at micromolar concentrations, slightly stimulated cell growth and cell density when cells were treated with interferon-γ/lipopolysaccharide (IFN-γ/LPS). At 1 μM, arsenate and cacodylate also slightly increased IFN-γ/LPS-induced nitric oxide (NO) synthesis in this cell line, consistent with the increase in cell number observed, whereas 1 μM arsenite significantly increased NO production on a per-cell basis. In contrast, arsenite significantly inhibited NO synthesis at concentrations above 10 μM arsenite as, to a lesser extent, did arsenate and cacodylate. These results suggest that ingestion of arsenicals could alter cellular generation of NO and interfere with its associated physiological functions. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
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  • 140
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 67-67 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 141
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 153-161 
    ISSN: 0268-2605
    Schlagwort(e): polyimides ; solution polycondensation ; seven-membered cyclic polyimide intermediate ; polyimide-silica gel hybrids ; sol-gel reaction ; pyrolysis ; pore size ; surface area ; adsorption-desorption isotherms ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A facile preparation of polyimide-silica gel hybrids by the simultaneous in-situ formation of polyimides during the hydrolysis-condensation of tetramethoxysilane (TMOS) is reported here. The hydrolysis and condensation of TMOS was carried out in a solution of DMAc containing 5% LiCl, CaCl2 or ZnCl2 and the seven-membered cyclic polyimide intermediate. The seven-membered cyclic intermediates, precursors of polyimides, were derived from the low-temperature polycondensation of dianhydrides [benzophenonetetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA), and 4,4-bis(hexafluoroisopropylidene)phthalic dianhydride (6FDA)] and di-isocyanates [isophorone di-isocyanate (IPDI), toluene di-isocyanate (TDI), hexamethylene di-isocyanate (HDI) and 4,4′-diphenylmethane di-isocyanate (MDI)]. These intermediates could readily be converted to the corresponding polyimides. Films were cast from the resulting mixtures and the solvent was gradually evaporated at 130 °C to result in the formation of clear, transparent, pale yellow or amber-colored hybrid films in which the salts were dispersed at the molecular level. Pyrolysis of polyimide-silica gel hybrids at 600 °C gave mesoporous silica. Silica gel obtained from hybrids HPI-8 (containing no salt) and HPI-11 (containing ZnCl2) had a pore radius (BJH method) of 2.9 nm, while that from hybrid HPI-9 (containing LiCl) had a pore radius of 11.4 nm. The surface areas (BET method) obtained were 203 m2 g-1, 19 m2 g-1 and 285 m2 g-1, while the pore volumes were 0.373 cm3 g-1, 0.158 cm3 g-1 and 0.387 cm3 g-1, respectively, for samples obtained from hybrids HPI-8, HPI-9 and HPI-11. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Ill.
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  • 142
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 223-230 
    ISSN: 0268-2605
    Schlagwort(e): butyltin ; TBT ; Ganges river ; dolphin ; pollution ; food chain ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Concentrations of butyltin compounds (mono-, di-, and tri-butyltin) were determined in dolphin (Platanista gangetica), fish, invertebrates and sediment collected from the River Ganges, India, in order to understand the contamination levels, sources, and potential for biomagnification in freshwater food chains. Total butyltin concentration in dolphin tissues was up to 2000 ng g-1 wet wt, which was about 5-10 times higher than in their diet. The concentrations in fish and benthic invertebrates, including polychaetes, were 3-10 times greater than in sediment. The biomagnification factor for butyltins in river dolphin from its food was in the range 0.2-7.5. Butyltin concentrations in Ganges river organisms were higher than those reported for several persistent organochlorine compounds. Discharge of untreated domestic sewage was one of the major sources of butyltin residues in Ganges river biota. High concentrations of butyltin compounds in freshwater food chains suggest the need to assess their toxic effects in aquatic organisms and to regulate their use. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 1 Ill.
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  • 143
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 251-255 
    ISSN: 0268-2605
    Schlagwort(e): enzyme ; arsonate ; biochemistry ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Enzymes that act on substrates R-O-PO3H2 often work on substrate analogues R-O-AsO3H2; such substrates are unstable, since esters of H3AsO4 hydrolyse easily. They also form easily, so that an enzyme that acts on R-O-PO3H2 often acts on a mixture of R-OH and arsenate via an ester that forms at the active site. Similarly coenzyme analogues may be formed; for example, a stable and active aspartate aminotransferase forms from the apoenzyme with free pyridoxal and arsenate.Enzymes that convert R-O-PO3H2 into a diester often act on R-CH2-AsO3H2, a stable substrate analogue; then the product is unstable and hydrolyses to re-form the analogue, giving a futile cycle. For example, RNA polymerase acquires exonuclease activity in the presence of H2O3P-CH2-AsO3H2; adenylate kinase acquires ATPase activity in the presence of the arsonomethyl analogue of AMP.A recent observation is that HO-CH2-CHOH-CH2-CH2-AsO3H2 is a good substrate for glycerol-3-phosphate dehydrogenase. The product is unstable and eliminates arsenite, sharing this ability with other 3-oxoalkylarsonates. Thus this enzyme-catalysed oxidation is a lethal synthesis, in view of the toxicity of arsenite. Another unusual biochemical reaction of an arsonic acid is seen in the ability of a bacterium to use arsonoacetate as its sole source of carbon and energy.In contrast with the elimination of arsenite by 3-oxoalylarsonic acids, 3-oxoalkylphosphonic acids, R-CO-CH2-CH2-PO3H2, are stable. 2-Oxoalkylphosphonic acids, R-CO-CH2-PO3H2, however, are moderately unstable to hydrolysis, yielding phosphate and R-CO-CH3. 2-Oxoalkylarsonic acids, R-CO-CH2-AsO3H2, decompose in the same way, but much more readily, yielding arsenate. © 1997 by John Wiley & Sons, Ltd.
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  • 144
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 313-326 
    ISSN: 0268-2605
    Schlagwort(e): selenium ; biogeochemical cycle ; Anadara trapezia ; Mugil cephalus ; selenocysteine ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Data on the factors affecting the accumulation of selenium in the cockle Anadara trapezia and mullet Mugil cephalus are presented, together with the distribution and speciation of selenium in tissues. Selenium concentration in whole cockles showed a small but significant decrease with weight. No further decrease in selenium concentration was apparent once an organism reached 0.25 g dry weight. Selenium concentration in cockles was not dependent on sex. The tissue distribution of selenium concentration in cockles was in the order gill〉intestine〉adductor〉mantle 〉foot.Selenium concentrations in liver tissues of mullet increased with the whole weight of the fish. In contrast, selenium concentrations in muscle, stomach, heart and kidney tissues were fairly low and constant in fish weighing less than 200 g (20 cm in length). Fish of greater weight and size (〉250 g and 〉30 cm) had higher and more variable selenium concentrations. No differences in selenium concentration between male and female fish occurred; however, the sex of many of the fish could not be distinguished. The tissue distribution of selenium concentration in mullet was in the order liver〉stomach〉heart〉muscle〉kidney.Most of the selenium recovered from both the cockle tissues and the mullet muscle tissues was found to be associated with proteins and to be present as selenocysteine. A conceptual model is presented for selenium transformations in marine organisms based on the formation of selenoamino-acids and subsequent incorporation into proteins. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 8 Ill.
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  • 145
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 327-335 
    ISSN: 0268-2605
    Schlagwort(e): arsenic ; urine ; HPLC-ICP-MS ; arsenobetaine ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Arsenic compounds were determined in 21 urine samples collected from a male volunteer. The volunteer was exposed to arsenic through either consumption of codfish or inhalation of small amounts of (CH3)3As present in the laboratory air. The arsenic compounds in the urine were separated and quantified with an HPLC-ICP-MS system equipped with a hydraulic high-pressure nebulizer. This method has a determination limit of 0.5 μg As dm-3 urine. To eliminate the influence of the density of the urine, creatinine was determined and all concentrations of arsenic compounds were expressed in μg As g-1 creatinine. The concentrations of arsenite, arsenate and methylarsonic acid in the urine were not influenced by the consumption of seafood. Exposure to trimethylarsine doubled the concentration of arsenate and increased the concentration of methylarsonic acid drastically (0.5 to 5 μg As g-1 creatinine). The concentration of dimethylarsinic acid was elevated after the first consumption of fish (2.8 to 4.3 μg As g-1 creatinine), after the second consumption of fish (4.9 to 26.5 μg As g-1 creatinine) and after exposure to trimethyl- arsine (2.9 to 9.6 μg As g-1 creatinine). As expected, the concentration of arsenobetaine in the urine increased 30- to 50-fold after the first consumption of codfish. Surprisingly, the concentration of arsenobetaine also increased after exposure to trimethylarsine, from a background of approximately 1 μg As g-1 creatinine up to 33.1 μg As g-1 creatinine. Arsenobetaine was detected in all the urine samples investigated. The arsenobetaine in the urine not ascribable to consumed seafood could come from food items of terrestrial origin that - unknown to us - contain arsenobetaine. The possibility that the human body is capable of metabolizing trimethyl- arsine to arsenobetaine must be considered. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 146
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 369-379 
    ISSN: 0268-2605
    Schlagwort(e): efflux ; liposomes ; dimethylarsinic acid ; membrane modification ; egg phosphatidylcholine ; bilayer ; tributyltin chloride ; monobutyltin trichloride ; facilitated diffusion ; NMR ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The efflux of dimethylarsinic acid (DMA) from liposomes formed from egg phosphatidylcholine (EPC) is increased when tributyltin chloride (TBT) is added to the extraliposomal compartment; however the addition of monobutyltin trichloride (MBT) slows down the efflux. When the liposomes are prepared from EPC and organotin compounds, different mechanisms for DMA efflux seem to operate: TBT-EPC liposomes show a mixture of facilitated and passive diffusion; MBT-EPC liposomes show only passive diffusion. The facilitated diffusion of DMA- seems to be stopped by the addition of TBT to the extraliposomal compartment. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 147
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 353-368 
    ISSN: 0268-2605
    Schlagwort(e): dsorption ; disease ; environmental chemistry ; non-covalent surface interactions ; pathology ; silicone ; toxicity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: While most organometallics enter the en- vironment through their industrial release, silicones are organometallic compounds purposefully introduced in high volume directly into healthy humans. A chemically centered study of the behavior of silicones in the biological environment reveals numerous de- gradative reactions and surface interactions that can produce bioreactive substances. Data from a variety of disciplines suggest that the preponderance of evidence supports the argument that silicone is a toxic organometallic. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
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  • 148
    ISSN: 0268-2605
    Schlagwort(e): halophytes ; arsenobetaine ; arsenocholine ; tetramethylarsonium ; arsenosugars ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Five species of halophytes were sampled in the salt marshes of the Tagus estuary, dried, ground and digested. They were further extracted with ethanol and the extracts passed through weak and strong cationic ion-exchange resins, purified through TLC and submitted to pyrolysis mass spectrometry and HPLC-ICP/MS. Arsenic content and hydride-forming arsenic species were verified, in each step, by GF-AA and HG-QFAA. A high content of arsenic was found in the samples of halophytes studied, both di- and tri-methylated arsenic compounds being present. A considerable fraction of this arsenic content seems to be refractory to hydride generation. Moreover, the arsenic fraction found seems to have the same ion-exchange behaviour as the refractory fractions formerly studied in estuarine water.A partial characterization of these structures by pyrolysis-GC-MS suggests the presence of arsenobetaine and arsenocholine compounds. Furthermore, HPLC-ICP/MS data seem to confirm the presence of these compounds. In addition, the latter hyphenated technique strongly suggests the presence of a number of other organoarsenicals including tetramethylarsonium (TMAs), trimethylarsine oxide (TMAO), cacodylate (DMA) and possibly an arsenosugar-type compound. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 149
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 485-490 
    ISSN: 0268-2605
    Schlagwort(e): tin ; tributyltin ; brown trout ; timber treatments ; freshwater ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Total tin and tributyltin (TBT) concentrations were measured in the brown trout, Salmo trutta, in 1988 from three river systems that had been contaminated by losses of TBT from timber preservation plants. Mean total tin concentrations in trout muscle ranged from 0.07 to 0.48 mg/kg. In the more contaminated areas approximately 30% of this tin was in the form of TBT. © Crown copyright 1997.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 150
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 513-521 
    ISSN: 0268-2605
    Schlagwort(e): dithienyl(diorgano)germanes ; diorganometal(2,5-thiophene) polymers ; poly(organometal)thiophene ; optical properties ; electrical conductivity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The syntheses of several types of polymers containing silicon, germanium and tin in the main chain are described. Optical studies show that they exhibit absorption in the far-ultraviolet region of the spectrum (200-400 nm). Electrical studies show that these polymers behave as insulators. Preliminary studies indicate, that depending on the chemical structure of the backbone, it is possible to dope some of the polymers via partial oxidation in solution. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 151
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 67-68 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 152
    ISSN: 0268-2605
    Schlagwort(e): seleno-DL-cystine ; seleno-DL-methionine ; pKa ; HPLC ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We have determined the deprotonation constants (pKa) of seleno-DL-cystine and seleno-DL-methionine together with those of DL-cystine and DL-methionine for comparison, by potentiometric measurements. In the case of seleno-DL-cystine, the difference between the pKa values for the two amino groups was found to be only slightly lower than that observed for DL-cystine itself. In contrast, the difference between the two pKa values for the carboxylic groups was found to be much smaller for seleno-DL-cystine than for DL-cystine. In both seleno-amino-acids, the zwitterionic species appear to be dominant in the pH range between 4 and 7, while positively charged protonated species are found to be present at pH values lower than 4. Based on a knowledge of the ionic species distributions as a function of pH, we have proposed an interpretation for the chromatographic separation of selenocystine and selenomethionine by HPLC. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 153
    ISSN: 0268-2605
    Schlagwort(e): organotin ; solid-state NMR ; crystal structure ; antitumor activity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bis(dicyclohexylammonium) bis(2,6-pyridinedicarboxylato)dibutylstannate is assigned seven-fold coordination at tin on the basis of its 119Sn CP/MAS NMR chemical shift (δ=-424.9 ppm). The assignment has been corroborated by a crystal structure determination of its monohydrate, whose tin atom has the trans-C2SnNO4 pentagonal bipyramidal [Sn-C=2.040(9), 2.067(8) Å; C-Sn-C =168.9(5)°] geometry. One 2,6-pyridine- dicarboxylato group chelates to the tin atom (Sn-O=2.234(4), 2.260(4); Sn-N =2.279(5) Å) whereas the other binds through only one carboxyl -CO2 end (Sn-O=2.416(5), 2.441(5) Å). Hydrogen bonds link the cation and the stannate into a linear chain parallel to the b-axis. The lattice water molecule is hydrogen-bonded to the free carboxyl end. The anhydrous compound showed higher in vitro antitumor activity than those of carboplatin and cisplatin when screened against breast (MCF-7, EVSAT), colonic (WiDr), ovarian (IGROV) and renal (A498) carcinoma, and melanoma (M19 MEL) cell lines. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 154
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 137-146 
    ISSN: 0268-2605
    Schlagwort(e): CdTiO3 ; sol-gel ; thin films ; powders ; Raman spectroscopy ; X-ray diffraction (XRD) ; scanning electron microscopy (SEM) ; electrical properties ; structural properties ; humidity sensors ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cadmium titanate, CdTiO3, was prepared by the sol-gel technique in bulk and in thin film form. The thermal evolution of the gels and the phase changes were studied by thermo- gravimetric analysis (TGA), X-ray diffractometry (XRD) and Raman and energy-dispersive (EDS) spectroscopies. The morphology of the samples was observed using scanning electron microscopy (SEM). Gels heated to 800 °C gave rise to powders with only the ilmenite-like phase. The orthorhombic perovskite phase is the only crystalline phase observed after a 4 h heat-treatment at 1100 °C. With respect to the conventional preparation method by solid-state reaction, by the sol-gel method it is possible to prepare the ilmenite phase at lower temperatures and the perovskite phase in a shorter time. Clear, homogeneous thin films were obtained by the dip-coating method. The refraction index and the thickness of the films were measured using ellipsometry. The humidity-sensitive electrical properties were measured for thin films deposited on alumina substrates with comb-type gold electrodes, heated to 200 °C and 450 °C. The films heated to 200 °C, which still contained organics, showed a variation of the resistance of six orders of magnitude in the relative humidity (RH) range tested (4-87% RH). The films heated to 450 °C, made of ilmenite-type CdTiO3, were nearly insensitive to RH. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
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  • 155
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 107-127 
    ISSN: 0268-2605
    Schlagwort(e): sol-gel ; composite glass ; fiber ; dye laser ; optical power limiter ; nonlinear optics ; multiphasic nanostructured composites ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Sol-gel-processed organic-inorganic hybrid materials combine the merits of inorganic glass and organic molecules, and are therefore a class of materials with good potential for photonics. In this review, two approaches which have shown promising results for producing useful materials for photonics are described: (i) a novel way to fabricate organically doped, multiphasic nanostructured composite monoliths and (ii) a method of fabrication of organically doped, sol-gel-derived optical fibers. For each approach, the preparation process is presented, together with selected applications such as multidye solid-state tunable laser, multiphasic optical power limiter, a micron-scale chemical-sensing and biosensing fibers and solid-state dye-doped fiber lasers. © 1997 by John Wiley & Sons Ltd.
    Zusätzliches Material: 16 Ill.
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  • 156
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 231-235 
    ISSN: 0268-2605
    Schlagwort(e): electron spin resonance ; spin-labeling ; doxyl-stearic acid ; erythrocyte ; organotin compounds ; hemolysis ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Various organotin compounds caused strong hemolysis of erythrocytes. To investigate the mechanism of hemolysis, spin-labeling techniques with electron spin resonance (ESR) spectroscopy were used and the relationship between hemolytic toxicity and signal intensity was investigated. Two kinds of spin-labeled stearic acid in which the para- magnetic center was located at different sites on the alkyl chain (5- and 12-doxyl-stearic acids; 5- and 12-NS) were used. It became clear that the decrease of ESR signal intensity was related to the hemolytic toxicity of the organotin compounds. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 157
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 213-221 
    ISSN: 0268-2605
    Schlagwort(e): laser fusion ; titanium ; metal-containing polymer ; titanocene ; carboxylic acid ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Linear, soluble copolymers containing titanium are of interest for use in targets for inertial-confinement fusion (ICF) experiments because the titanium is a useful spectroscopic probe for studying the nuclear fusion process. We have studied the reactions of dichloro- titanocene and diphenyltitanocene with carboxylic acids to determine if these can be used to prepare such polymers. Model reactions of dichlorotitanocene with p-toluic acid show that both mono- and di-carboxylates are formed. We have prepared a soluble titanium-containing copolymer via the reaction of poly(styrene-co-methacrylic acid) with an excess of dichlorotitanocene but attempts to remove the excess molecular titanocene from the copolymer result in crosslinking of the copolymer. Model reactions of benzoic and pivalic acids with diphenyltitanocene demonstrate that monosubstituted carboxylato(phenyl)titanocenes are formed but that these products are stable only at low temperatures and decompose readily at ambient temperature. Proton NMR studies of the reaction of diphenyltitanocene and benzoic acid at -20 °C indicate that this reaction is second order, suggesting that the reaction does not proceed through a benzyne intermediate. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 1 Ill.
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  • 158
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 237-247 
    ISSN: 0268-2605
    Schlagwort(e): Rochow reaction ; copper silicides ; η-Cu3Si ; promoters ; scanning electron microscopy (SEM) ; energy-dispersive X-ray spectroscopy (EDX) ; scanning Auger microscopy (SAM) ; Auger electron spectroscopy (AES) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Appropriate Rochow contact masses have been investigated by the spatial resolution techniques SEM-EDX and SAM-AES. The results gave evidence of the existence and the catalytic action of (X-ray)-amorphous copper-silicon (Cu-Si) surface species, i.e. extremely highly dispersed particles or two-dimensional species. The well-known Rochow promoter zinc seems to act as a moderator rather than as a real accelerator. It ensures a stable rate for the reaction by neutralizing the detrimental action of silicon impurities. The silicon impurities make the whole of the silicon surface reactive and in this way cause a general blockade of the silicon surface by inactive copper species. Zinc localizes the reaction. The silicon surface remains partly free, and active Cu-Si surface species can be formed by lateral diffusion of copper onto the silicon surface that is still free. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 159
    ISSN: 0268-2605
    Schlagwort(e): arsenobetaine ; microorganisms ; sinking particles ; deep sea ; trimethylarsine oxide ; dimethylarsinic acid ; inorganic arsenic ; degradation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The arsenobetaine-decomposing ability of microorganisms occurring in sinking particles, which play a main role in the vertical transport of organic substances produced in the photic zone, was investigated. The microorganisms in particles collected in the deep sea, 1100 and 3500 m in depth, clearly showed decomposing ability. With the particles from 1100 m, the degradation products were the same as those produced by microorganisms occurring in sources in the photic zone, i.e. trimethylarsine oxide (TMAO), dimethylarsinic acid (DMA) and inorganic arsenic(V). At 3500 m, the degradation activity was diminished, smalls amount of DMA and TMAO being produced. These results suggest that arsenobetaine contained in the animals starts to degrade immediately after the death of the animals and their transformation to particles. The degradation of arsenobetaine to inorganic arsenic in our tentative arsenic cycle in marine ecosystems (inorganic arsenic to inorganic arsenic via the biosynthesis of arsenobetaine) may apply to the deep sea as well as to the photic zone. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 160
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 289-296 
    ISSN: 0268-2605
    Schlagwort(e): mushrooms ; arsenic ; arsenobetaine ; arsenocholine ; hydraulic high-pressure nebulizer ; HPLC-HHPN-ICP-MS ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Three mushroom species from two old arsenic smelter sites in Austria were analyzed for arsenic compounds. The total arsenic concentrations were determined by ICP-MS. Collybia maculata contained 30.0 mg, Collybia butyracea 10.9 mg and Amanita muscaria 21.9 mg As kg-1 dry mass. The arsenic compounds extracted with methanol/water (9:1) from the dried mushroom powders were separated by HPLC on anion-exchange and reversed-phase columns and detected by ICP-MS using a hydraulic high-pressure nebulizer. In Collybia maculata almost all arsenic is present as arsenobetaine. Collybia butyracea contained mainly arsenobetaine (8.8 mg As kg-1 dry mass) and dimethylarsinic acid (1.9 mg As kg-1). Amanita muscaria contained arsenobetaine (15.1 mg As kg-1), traces of arsenite, dimethylarsinic acid and arsenate, and surprisingly arsenocholine (2.6 mg As kg-1) and a tetramethylarsonium salt (0.8 mg As kg-1). © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 161
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 345-349 
    ISSN: 0268-2605
    Schlagwort(e): siloxones ; sedimentary ; geochronology ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Selected samples of sediments from cores taken in the Ala Wai Canal (south-east Oahu, Hawaii) have been analyzed for organosilicon (silicone) content. Observed levels of silicone range from just above the detection limit (≈0.01 ppm) to over 1 ppm, and vertical distribution in the sediment column generally increases upwards, with the highest silicone content in the most contemporary sediments (dated independantly( by 210Pb and 137Cs measurements). Further, there is clear evidence of spike events (i.e. high levels of silicone in older, buried sediments) which appear to be associated with major, documented storm events on the island os Oahu. Silicone assay was by solvent extraction, and quantitative spectrophotometric measurement at 7.95 μm. The Ala Wai Canal is an anthropogenic hydorgraphic feature on Oahu. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
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  • 162
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 457-457 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 163
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 381-391 
    ISSN: 0268-2605
    Schlagwort(e): silicon-controlled ; bond formation ; cyclization ; allyltrimethylsilane ; 1,3-diketones ; β-ketoesters ; malonates ; ceric ammonium nitrate ; manganese(III) acetate ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effect of silicon on C-C bond formation between carbonyl compounds and allyltrimethylsilane was investigated. Treatment of 1,3-diketones, β-ketoesters or malonates with allyltrimethylsilane in the presence of ceric ammonium nitrate (CAN) in methanol produced the corresponding allylated products. Furthermore, introduction of Mn(OAc)3 · 2H2O into those reactions for replacement or assistance of CAN afforded silicon-containing cyclopentanes in 51-75% yields. A sequential process involving allylation, free-radical cyclization and elimination was also developed by use of CAN/Mn (OAc)3 · 2H2O/Cu(OAc)2 · H2O. Accordingly, β-ketoesters or malonates were allowed to react with allylsilanes in acetic acid to give silicon-containing cyclopentanes with an exo methylene unit in 52-71% yields. These reactions involved carbocationic and carboradical intermediates, of which formation and chemical activities were controlled by a β-silyl group. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Tab.
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  • 164
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 451-455 
    ISSN: 0268-2605
    Schlagwort(e): imposex ; Japanese sea snails ; organotin pollution ; tributyltin (TBT) ; triphenyltin (TPT) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A country-wide survey and laboratory experiments on imposex (a superimposition of male sex organs on female sea snails) in Japanese sea snails were carried out: 38 species were observed to be affected by imposex. For the rock shell, Thais clavigera, the percentage occurrence of imposex was 100% at almost all sites surveyed. The degree of imposex seemed to be positively correlated with the concentrations of tributyltin (TBT) and triphenyltin (TPT) in the species. The results of laboratory experiments showed that imposex in T. clavigera was initiated and promoted by both TBT and TPT. Many oviduct-blocked individuals, which were thought to be sterile, were observed in T. clavigera at sites near marinas and harbours. The effects of organotin pollution on the population of T. clavigera were observed at the sites near marinas. From the results of the additional country-wide survey on imposex in T. clavigera during 1993-1995, serious organotin pollution and imposex symptoms in the species are still continuing in Japan. © 1997 by John Wiley & Sons, Ltd.
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  • 165
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 539-540 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 166
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 415-437 
    ISSN: 0268-2605
    Schlagwort(e): lead ; alkyl-lead ; heavy metals ; analysis ; Hawaii ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In this paper we present and discuss heavy-metal concentrations in sediment cores from the Ala Wai Canal, a small urban drainage estuary in Honolulu, Hawaii (Oahu Island), and from selected soils and sediments collected in less impacted areas of Hawaii. We focus on lead and its isotope ratios to document the introduction, proliferation and subsequent phasing-out of alkyl-lead fuel additives in Honolulu over the past 60 years. Sedimentary lead increases from 〈10 ppm in the oldest (deepest) unimpacted portions of the cores to ˜750 ppm in sediments from the mid-1970s; lead contents then decrease to a range of 100-300 ppm in the most recent deposits.Lead concentrations in the canal sediments closely track the consumption of alkyl-lead fuel additives used on Oahu in the middle of this century. More than 90% of the lead in certain core intervals is of anthropogenic origin. Stable lead isotope ratios reflect changes in the estuary's sources of lead and show that this lead has an isotopic signature distinct from natural samples. Undisturbed layers of sediments in the Ala Wai canal track the average composition of anthropogenic lead used in its Honolulu watershed through time.The distinctive pattern of lead isotopes measured in Ala Wai Canal sediments can be used to distinguish anthropogenic from natural lead in Hawaiian rural locations. Soils located away from point-sources of contamination have isotopic compositions defined by mixtures of locally erupted volcanic rock, atmospheric dust and components similar to Ala Wai Canal anthropogenic lead. Natural lead concentrations in Hawaii are in the range of a few to a few tens of parts per million, with the high-concentration end-member occurring in a few selected intramountain basins where soils contain a significant component of continental dust fines scavenged by rainfall and concentrated by local geological conditions. Rural watershed material exhibits small but discernible elevations in lead concentrations due to anthropogenic effects.Other metals (cadmium, copper and zinc) in the Ala Wai Canal sediments also display patterns consistent with increased fluxes of metals attributable to anthropogenic activity. Unlike lead, no clear maxima are observed in sediments deposited during the mid 1970s. Rather, a continued input of these metals is attributed to expanding anthropogenic activity in the Ala Wai Canal watershed. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 11 Ill.
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  • 167
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 459-470 
    ISSN: 0268-2605
    Schlagwort(e): arsenocholine ; mushroom ; arsenobetaine ; arsenic compounds ; hydraulic high-pressure nebulizer ; ICP-MS ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Arsenic compounds were identified and quantified in the mushroom Amanita muscaria, collected close to a facility that had roasted arsenic ores. The powdered dried mushrooms were extracted with methanol/water (9:1), the extracts were concentrated and the concentrates were dissolved in water. The resulting solutions were chromatographed on anion-exchange, cation-exchange and reversed- phase columns. Arsenic was detected on-line with an ICP-MS detector equipped with a hydraulic high-pressure nebulizer. Arsenite, arsenate, dimethylarsinic acid and the tetramethylarsonium cation were minor arsenic compounds (∼2% each of the total 22 mg kg-1 dry mass), and arsenobetaine, arsenocholine (∼15% each) and several unidentified arsenic compounds (∼60%) were the major arsenic compounds in Amanita muscaria. The presence of arsenocholine (detected for the first time in a terrestrial sample) was ascertained by matching retention times in the anion-exchange, cation- exchange and reversed-phase chromatograms with the retention time of synthetic arsenocholine bromide and chromatographing extracts spiked with arsenocholine bromide. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
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  • 168
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 523-538 
    ISSN: 0268-2605
    Schlagwort(e): silicon-modified ; carbohydrate ; surfactant ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ionic siloxanyl-modified carbohydrate surfactants have been synthesized by alkylation/esterification of precursors containing tertiary amino functions. Depending on the reaction strategy, the siloxanyl moiety is part of the alkylating agent or the substrate. Polyhydroxylated tertiary amines can be quaternized by siloxanyl-modified chloroacetic acid esters or epoxysiloxanes in the presence of glacial acetic acid. The esterification of tertiary amines bearing carbohydrate and siloxanyl subunits by cyclic acid anhydrides yields, after neutralization, carboxylate salts. The reaction of hydroxyl groups and sulfamic acid leads to sulfates. The new substances were characterized by means of 13C NMR spectroscopy, gas chromatography, elemental analysis and their solubility profile. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 16 Ill.
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  • 169
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 551-558 
    ISSN: 0268-2605
    Schlagwort(e): chlorinated poly(vinyl chloride) ; organotins ; drinking water ; gas chromatography ; atomic absorption spectrometry ; ICP-MS ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A solid-phase extraction method, using a phenyl-bonded silica sorbent, was developed for the isolation of mono- and di-methyltin, -butyltin and -octyltin from drinking water. Recoveries averaged 92% over two tested sample weights and spiking levels. Ethyl derivatives were made by Grignard reaction for determination by gas chromatography-atomic absorption spectrometry (GC-AAS). Static and repetitive extraction studies were conducted at 24 and 65°C. Butyltins rapidly leached into drinking water kept in chlorinated poly(vinyl chloride) (CVPC) pipe samples. Monobutyltin and dibutyltin levels reached 19.8 (13.4 as Sn) and 197 (100.4 as Sn) ng g-1 respectively in water samples collected from CPVC pipe heated to 65°C. Butyltins were still leached from CPVC pipe after 20 repetitive extractions, suggesting that new CPVC water systems would contaminate water with organotins for some time after installation. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
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  • 170
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 577-581 
    ISSN: 0268-2605
    Schlagwort(e): dioxastannolanes ; antitumour ; human cell lines ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Six dibutyl-1,3,2-dioxastannolanes, including two enantiomeric pairs, exhibited greater in vitro antitumour activity towards a variety of human tumour cell lines than cisplatin but with little discrimination, suggesting hydrolysis to a common cytotoxic intermediate. A cell line hypersensitive to mitochondrial inhibitors (CI80-13S) was not sensitive to any of the test compounds, suggesting that cell mechanisms other than, or in addition to, mitochondrial function are targeted by tin antitumour agents. A pigmented melanoma cell line (MM418c5) was resistant to the test compounds, which were found to be sequestered by melanin. This resistance was not observed with triphenyltin hydroxide. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Ill.
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  • 171
    ISSN: 0268-2605
    Schlagwort(e): siloxanyl-modified ; carbohydrate ; surfactant ; wetting behaviour ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The siloxanyl-modified carbohydrate surfactants investigated consist of the four structural elements: (1) siloxanyl moiety; (2) spacer; (3) carbohydrate unit; and (4) modifying element. By static surface tension (γsν  -  γsβ α) measurements the contact angles of the aqueous surfactant solutions above the critical micelle formation concentration (cmc) on nonpolar perfluorinated surfaces (FEP® plate) were determined. Although the siloxanyl units were found to have a high capacity to level out the interfacial properties, both surface tension and wetting tension react independently to defined changes in the chemical structure of the surfactant molecules. The results of spreading experiments on polyproylene show good correlation with the dependences found by wetting meaurements. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 17 Ill.
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  • 172
    ISSN: 0268-2605
    Schlagwort(e): siloxane ; surface tension ; control angle ; interfacial tension ; wetting tension ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The surface tensions, wetting tensions, contact angles and solid/liquid interfacial tensions of defined siloxanes as well as those of analogous carbosilanes, polysilanes and neopentyl substituted silanes were determined. The wetting experiments were carried out on a glass plate coated with perfluoroalkyl methacrylate (FC 722®). The siloxanes possess the lowest surface tensions. Due to the presence of oxygen atoms in the siloxane backbone, a donor-acceptor portion (γ+/-lv) of the surface tension of about 1-2 mN/m was determined. The solid/liquid interfacial tension also contains a donor-acceptor portion (γ+/-sl). Its value is almost identical to that of γ+/-lv. The γ+/-sl differences between individual molecules of the same surface tension are responsible for contact angle differences of up to 4°. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 6 Ill.
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  • 173
    ISSN: 0268-2605
    Schlagwort(e): organotin(IV) ; porphine ; Mössbauer ; NMR ; development ; Ascidiaceae ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Diorgano- and triorgano-tin(IV) derivatives of meso-tetra(4-sulfonatophenyl)porphine (H4TPPS) with general formula (R2Sn)2TPPS and (R3Sn)4TPPS (TPPS4-=[meso-tetra(4-sulfonatophenyl)porphinate]4-, R=Me, Bu, Ph) have been obtained and their solid-state configuration inferred on the basis of IR and Mössbauer spectroscopy, while solution-phase studies have been carried out by 1H and 13C NMR in DMSO-d6, together with determination of the in vivo cytotoxicity of the new derivatives towards embryonic development of Ciona intestinalis. In particular, octahedral and trigonal-bipyramidal eq-R3Sn polymeric configurations are proposed, in the solid state, respectively for (R2Sn)2TPPS and (R3Sn)4TPPS complexes, with the arylsulfonate groups behaving as monoanionic bidentate bridging ligands.The 1H and 13C NMR data lead to the conclusion that the metal-to-ligand ratio (2:1 or 4:1), binding site (the sulfonato-group oxygens), and the coordination polyhedron around the metal (trans-octahedral or trigonal-bipyramidal) found in the solid state are preserved in solution. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 11 Ill.
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  • 174
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 755-756 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 175
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 31-37 
    ISSN: 0268-2605
    Schlagwort(e): methylcyclopentadienylmanganese tricarbonyl (MMT) ; gas chromatography ; helium microwave plasma atomic emission ; air ; soil ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A highly sensitive and specific method is described for the determination of methylcyclopentadienylmanganese tricarbonyl (MMT) in gasoline and environmental samples by gas chromatography-plasma atomic emission detection (GC-AED). The procedure is simple, rapid and free from interferences. The absolute limit of detection is 0.5 fg of MMT (0.5×10-15 g) expressed as Mn. The precision for replicate injections (n=5) of an MMT solution (10 pg Mn) was 2.8% relative standard deviation (RSD). Applications of the method to analysis of gasoline (petrol), and preliminary results of the analyses of environmental samples such as air and roadside dirt, are given. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
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  • 176
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 67-67 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 177
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 635-643 
    ISSN: 0268-2605
    Schlagwort(e): methylmercury ; superoxide dismutase ; mouse ; oxidative stress ; gene expression ; enzyme inhibition ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A study of alterations in two mammalian superoxide dismutases (SODs), Cu,Zn-SOD and Mn-SOD, caused by methylmercury has been reviewed. Mechanisms for the isozyme-selective decrease in MnSOD activity by the organometallic compound observed in vivo have been extensively examined by experiments with purified enzyme preparations. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
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  • 178
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 751-753 
    ISSN: 0268-2605
    Schlagwort(e): methylmercury ; radioactive ; synthesis ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A simple and fast synthesis of radioactive methylmercury is presented. It is based on the methylation of inorganic 203Hg(II) by methylcobalamin and isolation of resulting CH3203Hg(II) in a single extraction step. Time required is less than 4 hours and the final yield is ≥90%. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 1 Ill.
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  • 179
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 673-682 
    ISSN: 0268-2605
    Schlagwort(e): arsenic species ; mushrooms ; methylarsonic acid ; dimethylarsinic acid ; tetramethylarsonium ion ; arsenobetaine ; arsenocholine ; arsenite ; arsenate ; trimethylarsine oxide ; HPLC-ICP-MS ; taxonomy ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In 50 mushroom species (56 samples) from Slovenia, Switzerland, Brazil, Sweden, The Netherlands and USA, total arsenic was determined by radiochemical neutron activation analysis (RNAA). Arsenic concentrations ranged from 0.1 to 30 μg g-1 (dry mass). Arsenic compounds were determined in methanol extracts from the mushrooms by HPLC-ICP-MS. The aim of the study was not only to quantify arsenic compounds in mushrooms but also to uncover trends relating the methylating ability of a mushroom to its taxonomic or evolutionary status.The main arsenic compound found in many mushrooms (various puffballs, Agaricales and Aphyllophorales) was arsenobetaine. Arsenate [As(V)] was the main arsenic species in Laccaria fraterna and Entoloma rhodopolium and arsenite [As(III)] in Tricholoma sulphureum. A mixture of arsenite and arsenate was present in Amanita caesarea. Dimethylarsinic acid (DMA) and methylarsonic acid were present in many mushrooms, but generally as minor components. In Laccaria laccata, Leucocoprinus badhamii and Volvariella volvacea, DMA was the major metabolite. Arsenocholine (AC) and the tetramethylarsonium ion were present in a few species, generally at low concentrations, except for Sparassis crispa, in which AC was the main compound. Tri- methylarsine oxide was not found in any of the mushrooms. In some species small amounts of unknown compounds were also present. The possible taxonomic significance of the metabolite patterns and the predominance of arsenobetaine in more advanced fungal types are discussed. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
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  • 180
    ISSN: 0268-2605
    Schlagwort(e): geometry ; relative stability ; organotin(IV) derivatives ; 4-acylpyrazol-5-onates ; fungicidal ; insecticidal ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The fungicidal and insecticidal activities of the 4-acetyl (HPMAP) and 4-benzoyl (HPMBP) derivatives of 3-methyl-l-phenylpyrazol-5-one and their complexes with diorganotins [Bu2Sn(PMAP)2, Bu2Sn(PMBP)2, Ph2Sn(PMAP)2 and Ph2Sn(PMBP)2] and triorganotins [Bu3SnPMAP, Ph3SnPMAP, Bu3Sn(PMBP)(H2O) and Ph3SnPMBP] have been determined and their ED50 (fungicidal activity) and LC50 (insecticidal activity) values are reported. An attempt has been made to correlate the type of coordination geometry around the tin atom [based on published 119Sn NMR and 119Sn Mössbauer data as well as on the crystal structures of Bu2Sn(PMBP)2 and Bu3Sn(PMBP)(H2O)] and the relative stabilities with the observed bioactivities in these compounds. The diorganotin complexes are more effective than the triorganotins as insecticides. The effect of disproportionation of R3SnL to give R4Sn and R2SnL2 is discussed with respect to insecticidal activity. The stability constants of the diorganotin compounds are reported, and they suggest that these compounds are sufficiently stable to prevent appreciable ligand exchange before their assimilation into the living tissues of the insects. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
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  • 181
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 11-19 
    ISSN: 0268-2605
    Schlagwort(e): sulphur ; alkyltin compounds ; GC-FPD interference ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Elemental sulphur, a common constituent of marine sediments, has been shown to give dialkyl sulphides with the Grignard reagents commonly used to derivatize alkyltin species before their determination by gas chromatography with flame photometric detection (GC-FPD). Further, it has been demonstrated that even with the red filter for 610 nm (normally used for organotin compounds) fitted to the detector, sulphur compounds do give rise to an emission signal, which may be mistaken for tin emission from a pentylated or propylated alkyltin compound, as the respective retention times are in some cases quite close. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 8 Ill.
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  • 182
    ISSN: 0268-2605
    Schlagwort(e): organotin ; 2-thionaphthalene ; synthesis ; crystal structure ; biological activity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of di- and tri-organotin complexes of 2-thionaphthalene of general formula RR′R″SnL (R=R′=R″=C6H5, CH3, n-C4H9, C6H11, C6H5CH2; R=R′=C6H5CH2, R″=Cl; R=R′=Me, R″=C10H7S and L=2-thio-naphthalene, C10H7S) have been prepared by the reaction of di-or tri-organotin chloride(s) with 2-thionaphthalene. All compounds have been characterized by elemental analysis, IR, MS, NMR (1H, 13C, 119Sn) and 119Sn Mössbauer spectroscopies. X-ray crystal structures of the representative compounds (C6H5)3SnL and (CH3)2SnL2 confirm a tetrahydral geometry about tin. The biological activities of these compounds against various bacteria and fungi have been investigated. © 1997 by John Wiley & Sons, Ltd.
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  • 183
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 129-135 
    ISSN: 0268-2605
    Schlagwort(e): organic/inorganic gels ; interpenetrating networks ; polymer-impregnated gels ; organic-doped gels ; sol-gel process ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An attempt is made to classify transparent organic/inorganic materials synthesized by the sol-gel process. The chemical structures of the hybrids are the main criteria for this classification. Three main types of organic/inorganic gels are distinguished and their basic physico-chemical characteristics are outlined. © 1997 by John Wiley & Sons, Ltd.
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  • 184
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 71-106 
    ISSN: 0268-2605
    Schlagwort(e): polysilane ; poly(carbosilane) ; disilane ; oligosilane ; SiC fiber ; SiC precursor ; dehalocoupling ; dehydropolymerization ; disproportionation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Tailoring of polysilanes with given architectures and reactivities is a great challenge in the field of SiC pre-ceramic polymers. This paper reviews recent polysilane and related copolymer synthesis reactions.It is shown that the Wurtz-type polymerization of dichloro-, trichloro- or tetrachloro-silanes, so far the most extensively studied, enables access to a large variety of architectures ranging from one- to three-dimensional (3D) topologies, and based on secondary 〉SiR2, tertiary RSi(Si)3 or quaternary Si(Si)4 silicon units in the polymer backbone. These polysilanes usually present an intrinsic low reactivity, detrimental for fiber processing. Examples are given to illustrate how this reactivity can be increased by secondary substitution reactions, which create reactive entities that can favor further crosslinking reactions.Secondly a novel route involving heterogeneously catalyzed disproportionation of chloromethyldisilanes, developed in our laboratory, is reviewed which offers a direct access to polysilyne-type 3D architecture constituted by arrangements of fused rings. The Lewis-base catalyzed disproportionation mechanism is discussed and seems to involve donor-stabilized silylenes as key intermediates in the polymer formation process. The experimental results are supported by ab-initio quantum chemical calculations.Silylenes attack the Si sites of higher functionality causing a high regioselectivity for the exclusive formation of branched oligosilanes. The oligomers undergo thermally induced branching and crosslinking reactions leading to poly(chloromethylsilane)s. Obviously, there are analogies to the oligomer and polymer formation of the transition-metal complex catalyzed dehydropolymerzation of methyldisilanes. Poly(chloromethylsilane)s exhibit a high reactivity due to the presence of Si-Cl bonds.Disproportionation of chloromethyldisilanes in presence of olefins such as styrene provides promising polymer precursors for SiC fibers. Their rheological properties have been investigated for various styrene contents. The polymer fibers spun from melt are cured under ammonia, and then pyrolyzed to silicon carbide fibers, showing temperature resistance up to 1500 °C. © 1996 by John Wiley & Sons, Ltd.
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  • 185
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 205-212 
    ISSN: 0268-2605
    Schlagwort(e): urinary steroids ; per-TMS derivatives ; GC-SIM/MS profiling ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Complete GC-SIM/MS separation and identification of 19 steroids (including several steroid isomers) in a male urine sample, as their per-trimethylsilyl ethers, is described. Trimethylsilylation of their functional groups (hydroxyl and carbonyl) was achieved by a rapid, simplified and one-step derivatization method, using N-methyl-N-trimethylsilyl-2,2,2,-trifluoroacetamide as the silylating agent and the solvent as well, along with catalytic amounts of trimethylsilyl iodide and dithioerythritol. Furthermore, a GC/MS method for the analysis of a synthetic mixture of underivatized urinary steroids is proposed. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 186
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 195-203 
    ISSN: 0268-2605
    Schlagwort(e): OMCVD ; ceramic ; thin films ; metallacycle ; titanium ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The four-membered-ring heterocyclic molecule Cp2TiCH2Si(Me2)NSiMe3 (1; Cp=η-C5H5) was studied as a single-source precursor to titanium-based ceramic thin films. Its decomposition was studied at atmospheric and low pressure under nitrogen, argon and helium by TG-DTA-MS. Thin films containing the four elements of the metallacycle and oxygen were deposited on silicon substrates by low-pressure (20 Torr) chemical vapor deposition (CVD) between 773 and 923 K. Films were characterized by SEM-EDS, XPS, EPMA-WDS and XRD analyses. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 9 Ill.
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  • 187
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 257-264 
    ISSN: 0268-2605
    Schlagwort(e): tributyltin ; dibutyltin ; monobutyltin ; marine mammal ; water bird ; sea turtle ; tissue distribution ; metabolism ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Although organotins are notorious man-made organometallic species introduced into the aquatic environment, no investigation had been concerned with contamination of higher trophic animals such as marine mammals until the last few years. Our recent work demonstrated the detection of butyltin compounds (BTCs), including mono- (MBT), di-(DBT), and tri-butyltin (TBT) in marine mammals. This paper reviews BTC contamination in higher trophic animals, based on our recent publications. Analysis for BTCs showed significant accumulation in tissues and organs of three finless porpoises (Neophocaena phocaenoides) collected from Japanese coastal waters. More than 10 μg of butyltin ions per gram on a wet weight basis were detected in the liver of a porpoise collected in the semi-closed sea. Distribution of BTCs in the tissues and organs of the porpoises showed a similar pattern to several other marine mammal species: higher concentrations in liver and kidney, and lower in muscle and blubber. In addition, tissues and organs from two water birds and one sea turtle species were also analyzed for BTCs, and their concentrations and compositions were compared among the species. The results showed that the distribution of these contaminants extends widely, not only to marine mammals but also to other higher trophic species. On the other hand, the composition of the BTCs exhibited a specific profile in each species. The ratios of hepatic concentrations of DBT or MBT to TBT for marine mammals were relatively lower than those of water birds and the sea turtle, indicating that metabolism and excretion of TBT may be less efficient in the mammalian species. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
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  • 188
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 273-279 
    ISSN: 0268-2605
    Schlagwort(e): sediments ; adsorption ; desorption kinetics ; tributyltin ; dibutyltin ; zinc ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Adsorption-desorption equilibrium and de- sorption kinetic studies were conducted in order to assess desorption of tributyltin (TBT), dibutyltin (DBT) and zinc from resuspended sediment. Equilibria were described in terms of linear adsorption. Desorption kinetics were represented by a two-site model which assumed that desorption consisted of rapid desorption and first-order kinetic desorption. TBT desorbed the most easily. Desorption kinetic parameters were related to adsorption mechanisms. Some experimental results did not correspond with the theoretical model. This was thought to be caused by natural organic ligands originally held in the sediment. Zinc deviated the most, because it was affected by the natural organic ligands more strongly than butylins. For example the partition coefficient of zinc varied by up to 1000-fold, and re-adsorption to sediment of the zinc that had been discharged to the water took place. Release of chemicals induced by remedial dredging was assessed. Desorbed TBT may pose a high risk. Among remediation alternatives, capping or leaving the sediment to stand prior to in situ degradation are preferred. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 6 Ill.
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  • 189
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 281-287 
    ISSN: 0268-2605
    Schlagwort(e): arsenic ; marine animals ; analysis ; HPLC-ICP MS ; algae ; arsenobetaine ; trimethylarsine oxide ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The chemical forms of arsenic in some herbivorous or mainly herbivorous marine animals and, in some cases, the algae on which they feed were determined by HPLC-ICP MS. In most cases arsenobetaine was present in the animals as well as arsenosugars consumed directly from the algae. However in the case of copepods Gladioferens imparipes fed only on the diatom Chaetoceros concavicornis which had been grown in axenic culture, arseno-betaine was absent. Arsenobetaine was also absent from the muscle of the silver drummer Kyphosus sydneyanus, although trimethyl-arsine oxide was present. This is the first reported case of the absence of arsenobetaine in a marine teleost fish and may be related to its fermentative faculty for digesting the macroalgae that it consumes. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 1 Ill.
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  • 190
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 305-311 
    ISSN: 0268-2605
    Schlagwort(e): arsenic speciation ; seasonal change ; arsenic methylation ; redox conditions ; freshwater ; hypolimnion ; biological activity ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Seasonal changes in the distribution of arsenic species were observed in a dredged area in the southern basin of Lake Biwa, Japan. The concentrations of dimethylarsenic acid [DMAA(V)] became comparable with those of inorganic forms during a stratification period. DMAA(V) increased not only in the photic zone but also in the hypolimnion. In the photic zone, an increase in DMAA(V) was observed with the yearly maximum of water temperature. In the hypolimnion, the seasonal changes in methylarsenicals differed from those in surface waters. DMAA(V) maxima appeared seasonally under sub-anoxic conditions and developed regionally at the redox boundary and above the sediment surface. The DMAA(V) concentrations increased in the initial period of oxygen depletion and just after the disappearance of anoxia, while they diminished in the anoxic hypolimnion by midsummer. The seasonal behavior of trivalent methylarsenicals, which are readily oxidized in oxic environments, was similar to that of DMAA(V). The total arsenic concentration in the surface layer rose to a maximum in late summer. Methylarsenicals did not increase in such a way that the total arsenic concentration increased during summer. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 6 Ill.
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  • 191
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 249-249 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Issues 4 and 5 of Applied Organometallic Chemistry, vol. 11, 1997 consist of papers based on work presented at two Symposia held at the Pacifichem '95 Meeting in Honalulu, Hawaii. The papers published here were reviewed by the normal process of the Journal and are not verbatim accounts of the presentations themselves.
    Materialart: Digitale Medien
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  • 192
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 457-458 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 193
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 393-396 
    ISSN: 0268-2605
    Schlagwort(e): antimony ; accumulation ; excretion ; Chlorella vulgaris ; freshwater alga ; association mode ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The bioaccumulation and excretion of antimony by the freshwater alga Chlorella vulgaris, which had been isolated from an arsenic-polluted environment, are described. When this alga was cultured in a medium containing 50 μg cm-3 of antimony(III) for 14 days, it was found that Chlorella vulgaris bioaccumulated antimony at concentrations up to 12 000 μg Sb g-1 dry wt after six days' incubation. The antimony concentration in Chlorella vulgaris decreased from 2570 to 1610 μg Sb g-1 dry wt after the cells were transferred to an antimony-free medium. We found that the excreted antimony consists of 40% antimony(V) and 60% antimony(III). This means that the highly toxic antimony(III) was converted to the less toxic antimony (V) by the living organism.Antimony accumulated in living Chlorella vulgaris cells was solvent-fractionated with chloroform/methanol (2:1), and the extract residue was fractionated with 1% sodium dodecyl sulfate (SDS). Gel-filtration chromatography of the solubilized part showed that antimony was combined with proteins whose molecular weight was around 4×104 in the antimony-accumulated living cells. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 194
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 403-414 
    ISSN: 0268-2605
    Schlagwort(e): inorganic arsenic ; inorganic germanium ; monomethylarsonic acid (MMAA) ; dimethylarsinic acid (DMAA) ; monomethylgermanium (MMGe) ; arsenic species ; germanium species ; seawater ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The vertical profiles of inorganic arsenic [As(III)+As(V)], monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA), inorganic germanium and monomethylgermanium (MMGe) were investigated at three sampling stations in the Pacific Ocean. In addition, the concentrations of these species in various surface waters have also been determined.The vertical profile of both inorganic arsenic and germanium displayed low concentrations, 1100 to 1450 ng dm3 for inorganic arsenic and 〈0.7 to 2 ng dm3 for inorganic germanium, in the surface zone. The concentrations of inorganic arsenic increased with depth to maximum concentrations that varied from 1500 to 2200 ng dm3 at a depth of 2000 m and then slowly decreased to concentrations that varied from 1300 to 1900 ng dm3 at a depth of 5000 m. On the other hand, the vertical profiles of inorganic germanium displayed a relatively constant concentration (4 to 8 ng dm3) from a depth of 2000 m to 5000 m. These vertical profiles of inorganic germanium were linearly correlated with those of silicate with a Ge/Si molar ratio of 0.715×106.Both MMAA and DMAA displayed maximum concentrations in surface water and abruptly dropped with depth from 0 to 200 m. The concentration in surface water was 12 ng dm3 for MMAA and varied from 48 to 185 ng dm3 for DMAA. At depths 〉200 m, MMAA and DMAA were generally at comparable concentrations of about 3 ng dm3. In the case of MMGe, it was uniformly distributed throughout the water column at a concentration of approximately 16 ng dm3, indicating that MMGe was not involved in the biogeochemical cycling of inorganic germanium.In deep waters (〉200 m), the concentrations of both inorganic arsenic and germanium increased from the southern Tasman Sea to the north. The increase in inorganic arsenic concentration was linearly correlated with that of phosphate and the increase in inorganic germanium concentration was linearly correlated with that of silicate, with apparent δAs/δP and δGe/δSi molar ratios of 4.53×103 and 0.73×106, respectively. © 1997 by John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
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  • 195
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 471-483 
    ISSN: 0268-2605
    Schlagwort(e): organoantimony ; trimethylstibine ; trimethylantimony ; biomethylation ; antimonyltartrate ; hexahydroxyantimonate ; Pseudomonas fluorescens ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We have evidence that an organic and an inorganic salt of antimony were reduced and methylated biologically by microorganisms in laboratory experiments. The organoantimony compound produced was trimethylstibine [(CH3)3Sb] and was detected in a culture headspace. This was confirmed by matching the compound's retention time in capillary gas chromatography, as detected by fluorine-induced chemiluminescence, with a com- mercial standard and by its mass spectrum determined with gas chromatography/ mass spectrometry (GC-MS). (CH3)3Sb was detected in the headspace of soil samples amended with either potassium antimonyltartrate or potassium hexahydroxyantimonate and augmented with any one of three different nitrate-containing growth media. The identity of the microorganisms in soil that accomplished this are as yet unknown. Of 48 soil samples amended with these two compounds, 24 produced trimethylstibine. Bioreduction of trimethyldibromoantimony was also detected in a liquid monoculture of Pseudomonas fluorescens K27 which also produced tri- methylstibine. This headspace production of (CH3)3Sb was determined to be linked to the culture's cell population as measured by optical density. This microbe, however, did not biomethylate either potassium antimonyltartrate or potassium hexahydroxyantimonate in any experiments we performed. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
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  • 196
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 633-633 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 197
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 559-564 
    ISSN: 0268-2605
    Schlagwort(e): metal chelates ; anti-inflammatory ; arthritis ; gastric ; irritancy ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: N-Phenylbenzamide-2,2′-dicarboxylic acid (PBDA) and its copper(II), nickel(II), cobalt (II), zinc(II) and manganese(II) chelates have been synthesized and characterized by their physical measurements, infrared and electronic spectra and magnetic moment data. In an acute anti-inflammatory test, the cobalt chelate was most active (31.1% inhibition) followed by the zinc and copper chelates, whereas the copper chelate (22.3% inhibition) was most active in an adjuvant arthritis test. Again the cobalt chelate was most active in the cotton-wad granuloma test. Gastric irritancy was markedly reduced after chelation by copper, followed in order by zinc, cobalt, manganese and nickel chelates. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Tab.
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  • 198
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 583-589 
    ISSN: 0268-2605
    Schlagwort(e): electroreduction ; di-n-hexyldichlorogermane ; poly(di-n-hexylgermane) ; sacrificial anode ; organic media ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effects of the nature of the electrodes (sacrificial anode and cathode) and of the solvent on the electroreduction of di-n-hexyldichlorogermane have been investigated. Several sacrificial anodes (magnesium, zinc and aluminium) and cathodes, including stainless steel, magnesium and aluminium, have been used in THF containing LiClO4. Monomodal and polymodal poly(di-n-hexylgermanes) were obtained with Al/Al and Mg/Mg electrode pairs, but the polymer yield was about twice as high with Al/Al (64%) as with Mg/Mg (30%). Various solvents (tetrahydrofuran, hexamethylphosphorotriamide, N,N-dimethylacetamide, acetonitrile and dimethylformamide) with LiClO4 have been used as electrolytic media. Monomodal PDHG with a relatively narrow molecular weight distribution ([M¯]w/[M¯]n=1.6) was obtained only in THF/HMPA with Al/stainless steel electrodes. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
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  • 199
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 705-706 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 200
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 667-671 
    ISSN: 0268-2605
    Schlagwort(e): vinyl-substituted silanes ; allylsilanes ; short-chain alkenylsilanes ; silylalkenes ; ruthenium catalyst ; cross-metathesis ; dehydrogenative silylation ; olefins ; vinylsilane ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In the cross-metathesis reaction of tri(methyl, ethoxy)vinylsilanes with propene and/or 1-butene catalyzed by RuCl2(PPh3)3 activated in benzene at 115-130 °C, a series of l-alkenylsilanes of general formula CH3(CH2)mCH = CHSiMe3-n(OEt)n, where m=0, 1, and n=0-3 (1-silyl-1-alkenes), as well as of formula CH2=C(Me)SiMe3-n(OEt)n, where n=1, 2 (2-silyl-1-alkenes), were obtained. Additional products determined were allysilanes of general formula CH2=CHCH2SiMe3-n(OEt)n and CH3CH= CHCH2SiMe3-n(OEt)n, where n=1-3. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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