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  • 1995-1999  (747)
  • Industrial Chemistry and Chemical Engineering  (746)
  • Nuclear reactions
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Space science reviews 84 (1998), S. 199-206 
    ISSN: 1572-9672
    Keywords: Nuclear reactions ; Nucleosynthesis ; Abundances ; Stars:Evolution ; Interior ; Rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We first recall the observational and theoretical facts that constitute the so-called 3He problem. We then review the chemical anomalies that could be related to the destruction of 3He in red giants stars. We show how a simple consistent mechanism can lead to the destruction of 3He in low mass stars and simultaneously account for the low 12C/13C ratios and low lithium abundances observed in giant stars of different populations. This process should both naturally account for the recent measurements of 3He/H in galactic HII regions and allow for high values of 3He observed in some planetary nebulae. We propose a simple statistical estimation of the fraction of stars that may be affected by this process.
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  • 2
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0268-2605
    Keywords: triarylantimony dichrysanthemate ; plant growth-regulating activity ; crystal structure ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of triarylantimony dichrysanthemate compounds of the type Ar3Sb(O2CR)2 [Ar=C6H5, 4-CH3C6H4, 3-CH3C6H4, -CH3C6H4, 4-ClC6H4; R=4-ClC6H4CH(i-Pr), cis-Cl2C:CH trans-Cl2C:CH] have been synthesized and characterized by elemental analysis, infrared spectra, 1H NMR spectra and mass spectra. Some activities of these compounds in plant growth regulation have been determined. Their results indicate that the derivatives of cis-dichlorochrysanthemic acid and trans-dichlorochrysanthemic acid significantly promote rooting of excised cucumber cotyledons at 10 ppm. An X ray structure determination has been carried out as follows for Ph3Sb(O2CCHCMe2CMe2)2: orthorhombic, space group Pbcn, Z=4, structure solution with 2385 independent reflections, R=0.035. Lattice dimensions at 26 °C: a=15.616(3) Å, b=10.275(2) Å, c=20.201(5) Å, V=3241(2) Å3, ρ=1.302 g cm-3. © 1998 John Wiley & Sons, Ltd.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 39-46 
    ISSN: 0268-2605
    Keywords: organotin(IV): organosilicon(IV) complexes ; thiosemicarbazones ; antimicrobial studies ; NMR spectra ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diorganotin(IV) and diorganosilicon(IV) derivatives of the types R2MCl(TSCZ) and R2M(TSCZ)2 (where TSCZ is the anion of a thiosemicarbazone ligand, R=Ph or Me and M=Sn or Si) have been synthesized and characterized by elemental analyses, molecular weight determinations and conductivity measurements. The mode of bonding has been established on the basis of IR and 1H, 13C 29Si and 119Sn NMR spectroscopic studies. Some of the representative complexes have also been evaluated for their antimicrobial effects on different species of pathogenic fungi and bacteria in vivoas well as in vitro.The results of these investigations are reported. © 1998 John Wiley & Sons, Ltd.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 145-145 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 1-12 
    ISSN: 0268-2605
    Keywords: reaction ; morin ; hydroxyflavone ; preconcentration ; sample clean-up ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analytical procedure for the determination of phenyltin compounds in environmental sample waters was studied. Chromatography of mono-, di- tri-phenyltin (MPT, DPT and TPT) was performed on a reversed-phase C18 column with the mobile phase comprising methanol/10-2 M H3PO4 (80:20 v/v) at pH 3 and UV detection at 214 nm. To enhance the sensitivity of the detection system, the post-column reaction between morin or 3-hydroxyflavone and phenyltin compounds was formed before fluorescence detection. Several parameters affecting the fluorescence intensity were studied systematically, including the optimum condition for the post-column reagent that was also compatible with the eluent. The parameters concerned in this study were the pH, the percentage of Triton X-100, the ratio of fluorigenic reagent to phenyltin compounds and the amount of methanol in the eluent. Detection limits before the preconcentration process were in the region of 1.5 ppb for TPT and 150-250 ppb for MPT and DPT, respectively. Utilizing solid-phase extraction on a C18 cartridge for sample clean-up as well as preconcentration successfully reduced the detection limit of TPT to the level of ng dm-3 and can be applied to seawater analysis. Recovery in the range 95.0-98.0% was obtained by developing the optimum elution profile in the preconcentration step. © 1998 John Wiley & Sons, Ltd.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 59-65 
    ISSN: 0268-2605
    Keywords: cobaltocenium ; ferrocene ; Nafion ; phenytoin ; phenobarbital ; square-wave voltammetry ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two different cationic redox labels, i.e. a ferroceneammonium ion and a cobaltocenium ion, were covalently attached to two antiepileptics, phenytoin and phenobarbital, respectively. The two labeled drugs possess distinct standard redox potentials of 0.39 V for the phenytoin derivative and -0.92 V for phenobarbital derivative (vs Ag/AgCl, Cl- 0.05 M) at a carbon paste electrode. After preconcentration in a polyanionic Nafion-loaded carbon paste electrode the positively charged labeled phenytoin and phenobarbital derivatives could be simultaneously detected in concentration ranges which were relevant to the therapeutic ranges of the antiepileptics, with a view to a future dual-analyte immuno- assay. Square-wave voltammetry permitted detection limits of 5×10-8 M (for the phenytoin derivative) and 2.5×10-8 M (for the phenobarbital derivative) for non-simultaneous detection. © 1998 John Wiley & Sons, Ltd.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 79-85 
    ISSN: 0268-2605
    Keywords: organic tellurium compounds ; polycondensation ; amino groups ; polyamides ; polyurea ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several new and known organic tellurium compounds containing amino groups (i.e. ArTeBr3, Ar2Te2 and Ar2Te, where Ar= 4-NH2C6H4, 2-NH2C6H4, 4-CH3CONHC6H4 or 2-NH2-5-NO2-C6H3) were prepared by reacting aminoarylmercury chlorides with tellurium tetrabromide in glacial acetic acid. Bis(4-aminophenyl) telluride and bis(2-amino-5-nitrophenyl) telluride were polymerized with aromatic and aliphatic diacid chlorides (i.e. terephthaloyl chloride and sebacoyl chloride), as well as with toluene di-isocyanate, leading to new organic tellurium polyamides and polyurea. All organic tellurium compounds and their condensation polymers were characterized by elemental analyses, IR, 1H and 13C NMR, and mass spectroscopy. The thermal stabilities of the resulting polymers were determined by thermogravimetric and derivative thermogravimetric techniques. © 1998 John Wiley & Sons, Ltd.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 99-107 
    ISSN: 0268-2605
    Keywords: phenyltin ; model membrane ; hemolysis ; fluorescence ; 1H NMR ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenyltin compounds are known to be biologically active. Their chemical structure suggests that they are likely to interact with the lipid fraction of cell membranes. Using fluorescence and NMR techniques, the effect of phenyltin compounds on selected regions of model lipid bilayers formed from phosphatidylcholine was studied. The polarization of N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) dipalmitoyl-L-phosphatidylethanolamine and desorption of praseodymium ions was used to probe the polar region, whereas the polarization of 1 - (4 - trimethylammoniumphenyl) - 6 - phenyl - 1,3,5-hexatriene p-toluenesulfonate measured the hydrophobic core of the membrane. In addition, changes in the N-(5-fluoresceinthiocarbanoly)dipalmitoyl - L - α - phosphatidyl - ethanolamine fluorescence intensity indicated the amount of charge introduced by organotin compounds to the membrane surface. There were no relevant changes of measured parameters when tetraphenyltin was introduced to the vesicle suspension. Diphenyltin chloride causes changes of the hydrophobic region, whereas the triphenyltin chloride seems to adsorb in the headgroup region of the lipid bilayer. When the hemolytic activity of phenyltin compounds was measured, triphenyltin chloride was the most effective whereas diphenyltin chloride was much less effective. Tetraphenyltin causes little damage. Based on the presented data, a correlation between activity of those compounds to hemolysis (and toxicity) and the location of the compound within the lipid bilayer could be proposed. In order to inflict damage on the plasma membrane, the compound has to penetrate the lipid bilayer. Tetraphenyltin does not partition into the lipid fraction; therefore its destructive effect is negligible. The partition of the compound into the lipid phase is not sufficient enough, by itself, to change the structure of the lipid bilayer to a biologically relevant degree. The hemolytic potency seems to be dependent on the location of the compound within the lipid bilayer. Triphenyltin chloride which adsorbs on the surface of the membrane, causes a high level of hemolysis, whereas diphenyltin chloride, which penetrates much deeper, seems to have only limited potency. © 1998 John Wiley & Sons, Ltd.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 109-119 
    ISSN: 0268-2605
    Keywords: bioconcentration ; toxicity ; TBTCl ; tilapia ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acute toxicity (96 h) and bioconcentration experiments of tributyltin chloride (TBT) in tilapia were conducted in an aqueous solution with salinity of 15‰, and a toxicity mechanism has been suggested. The 96-h LC50 was 3.80 μg Sn l-1. Bioconcentration factors in different tissues increased in the order muscle〈gill〈viscera. Studies on the metabolism of TBT showed that it can be easily degraded to DBT (dibutyltin) in these tissues. Further degradation of DBT to MBT (monobutyltin) was much more difficult. A mesocosm was used for the first time to study the toxicity of TBT in tilapia. The result demonstrated that the TBT bioconcentration curve changed with the initial concentrations of TBT but the order of bioconcentration in the tissues did not change. © 1998 John Wiley & Sons, Ltd.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 145-145 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 12
    ISSN: 0268-2605
    Keywords: laser-assisted chemical vapor deposition ; SnO2 ; SnBr4 ; copper(II) acetate ; gas sensors ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser-assisted chemical vapor deposition (LCVD) was utilized to produce SnO2 films from SnBr4 plus air, O2 or N2O. SnO2 films were successfully generated using either 222 or 308 nm laser pulses but there was evidence for film contamination when using less than 60 mJ/pulse laser energies at 222 nm. Films were characterized using ultraviolet absorption spectroscopy; the spectra of films with impurities resembled the spectrum of SnBr4. AFM images were obtained which indicated that this LCVD route produced small and fairly uniform SnO2 grains which were 50-100 nm in size. Multiphoton ionization spectroscopy was used to verify that the dissociation of a film dopant precursor, copper(II) acetate, produced gas-phase copper atoms under conditions similar to those used in film deposition experiments. The deposition of SnO2 from SnBr4 plus an oxidant was found to be more efficient than from di-n-butyl tin diacetate but films produced via this new LCVD route, including those doped with copper, were found to be much less sensitive in preliminary gas-sensing screening. © 1998 John Wiley & Sons, Ltd.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 341-346 
    ISSN: 0268-2605
    Keywords: silver halides ; nanoparticles ; pseudoisocyanine ; stability ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudoisocyanine (PIC) was adsorbed on colloidal silver halide nanoparticles where it formed aggregates (J-aggregates). The nanoparticles were prepared using a surfactant (AOT)/n-heptane/water microemulsion. The molecules of pseudoisocyanine replaced the molecules of surfactant (AOT) on the surface of the nanoparticles and caused an instability of the silver bromide dispersion. The stability could be improved by two methods: either by using an adsorption inhibitor (e.g. p-xylene) or by adding another surfactant (CTAB). The adsorption has also been carried out at low temperature: the stability of the particles was then improved, and the J-aggregates are smaller. © 1998 John Wiley & Sons, Ltd.
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 353-360 
    ISSN: 0268-2605
    Keywords: surface chemistry ; sodium nanoclusters ; optical spectroscopy ; plasmon excitation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of molecular adsorbate layers on surface plasmon excitation in small supported metal particles has been investigated and exploited to study adsorption reactions on their surfaces. For this purpose sodium nanoclusters on quartz and LiF substrates served as model systems. Their optical transmission spectra are dominated by two maxima which are due to the excitation of surface plasmon resonances in the direction of the long and short axes of the oblate particles. By recording the spectra under ultrahigh-vacuum conditions and, subsequently, after exposure to gases such as O2, N2O, CO2, H2 and N2, changes in the optical spectra can be identified if the clusters are covered by as little as half a molecular monolayer. Depending on the adsorbed molecules, different modifications of the maximum position, the width and the amplitude of the surface plasmon resonances are observed. The results of a series of measurements together with calculations using the quasi-static approximation indicate that the variations in the spectra allow one to distinguish between physisorption and chemisorption, i.e. to characterize the strength of the chemical bond. In addition, diffusion of the molecules into the bulk of the particles can be detected. Particularly interesting is the observation that the clusters can experience a change in their shape if gases such as O2 or CO2 react with their surface. © 1998 John Wiley & Sons, Ltd.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 375-379 
    ISSN: 0268-2605
    Keywords: granular films ; pulsed laser deposition ; giant magnetoresistance ; microstructure ; magnetic properties ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An investigation into the microstructural properties of CoxAg1 - x films, grown by pulsed laser deposition, as a function of deposition and post-deposition annealing temperature is reported. Surface morphology and microstructure were investigated by XPS, SEM and TEM measurements. Magnetic measurements were used to gain further information on particle size distributions through the analysis of the temperature dependence of the irreversible magnetization. Depending on cobalt content, deposition and post-deposition annealing temperature, the maximum of the cobalt grains diameter distribution was estimated to be in the range 2-6 nm. © 1998 John Wiley & Sons, Ltd.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 381-386 
    ISSN: 0268-2605
    Keywords: nanoparticles ; magnetic susceptibility ; magnetic anisotropy ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dynamical behavior of γ-Fe2O3 particles dispersed in a polymer have been investigated by a.c. susceptibility and Mössbauer spectroscopy measurements. The effect of interparticle interactions on the relaxation time is satisfactorily described by a superparamagnetic model where the dipolar energy is determined by a statistical calculation for a disordered arrangement of particles with volume distribution and easy axes in random orientations. The results indicate that the single particle anisotropy energy is mainly determined by surface anisotropy and that the energy barrier increases with the interaction strength. © 1998 John Wiley & Sons, Ltd.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 305-314 
    ISSN: 0268-2605
    Keywords: mesoporous ; oxides ; nanostructures ; luminescence ; zeolites ; guest/host ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ordered porous inorganic compounds can now be synthesized with pore sizes between 0.3 nm and several tens of nanometers. The sharp pore size distribution of such materials and the ordered pore arrangement open possibilities for using them to organize matter on the nanometer scale. This overview highlights different aspects of this topic, using four selected examples: the spatial organization of molecules with high molecular hyperpolarizability to create a frequency-doubling element; the encapsulation of a laser dye which results in a new class of solid-state lasers; the encapsulation of small metal clusters in mesoporous ordered oxides; and the encapsulation of semiconductor clusters in such oxides. © 1998 John Wiley & Sons, Ltd.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 427-433 
    ISSN: 0268-2605
    Keywords: laser ; chemical vapour deposition ; thin films ; Si/C/H materials ; divinylsilane ; silicon carbide ; polycarbosilane ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transversely excited atmospheric (TEA) CO2 laser-induced decomposition of divinylsilane in the gas phase yields unsaturated C2-C4 hydrocarbons, benzene and vinylsilane, and it represents a convenient process for chemical vapour deposition of thin solid films composed of silicon carbide and polycarbosilane. © 1998 John Wiley & Sons, Ltd.
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  • 19
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 285-291 
    ISSN: 0268-2605
    Keywords: mushroom ; arsenic speciation ; HPLC-ICP-MS ; dimethylarsinic acid ; arsenobetaine ; trimethylarsine oxide ; toxicological evaluation ; soil contamination ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Samples of the edible mushroom Laccaria amethystina, which is known to accumulate arsenic, were collected from two uncontaminated beech forests and an arsenic-contaminated one in Denmark. The total arsenic concentration was 23 and 77 μg  As g-1 (dry weight) in the two uncontaminated samples and 1420 μg As g-1 in the contaminated sample. The arsenic species were liberated from the samples using focused microwave-assisted extraction, and were separated and detected by anion- and cation-exchange high-performance liquid chromatography with an inductively coupled plasma mass spectrometer as arsenic-selective detector. Dimethylarsinic acid accounted for 68-74%, methylarsonic acid for 0.3-2.9%, trimethylarsine oxide for 0.6-2.0% and arsenic acid for 0.1-6.1% of the total arsenic. The unextractable fraction of arsenic ranged between 15 and 32%. The results also showed that when growing in the highly arsenate-contaminated soil (500-800 μg As g-1) the mushrooms or their associated bacteria were able to biosynthesize dimethylarsinic acid from arsinic acid in the soil. Furthermore, arsenobetaine and trimethylarsine oxide were detected for the first time in Laccaria amethystina. Additionally, unidentified arsenic species were detected in the mushroom. The finding of arsenobetaine and trimethylarsine oxide in low amounts in the mushrooms showed that synthesis of this arsenical in nature is not restricted to marine biota. In order to minimize the toxicological risk of arsenic to humans it is recommended not to consume Laccaria amethystina mushrooms collected from the highly contaminated soil, because of a genotoxic effect of dimethylarsinic acid observed at high doses in animal experiments. © 1998 John Wiley & Sons, Ltd.No Abstract.
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  • 20
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 475-478 
    ISSN: 0268-2605
    Keywords: organomercurials ; symmetrization ; column chromatography ; organomercury halides ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The symmetrization reaction of organomercury(II) chlorides (RHgCl) to R2Hg and HgCl2 in toluene solution under identical conditions using a basic alumina column has been studied­in order to compare the effect of the nature of the R groups on the extent of symmetrization. The efficiency of symmetrization depends markedly on the electron-withdrawing nature of­R, varying from 90-94% for R = trichlorovinyl or phenyl to 11% for R = 2,6-dimethylphenyl.© 1998 John Wiley & Sons, Ltd.
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  • 21
    ISSN: 0268-2605
    Keywords: iron ; clusters ; magnetic properties ; laser vaporization ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Clusters of iron produced in a laser vaporization source have been characterized with time-of-flight spectra and deposited on different substrates for production of films of varying thickness. The magnetic properties of these films with thicknesses of 60 and 120 nm were investigated using an alternating gradient magnetometer. The films exhibit mono-domain behavior from a broad size distribution which has been confirmed by transmission electron microscopy. Films were also investigated by Mössbauer spectroscopy, which showed fast relaxation in the particles at room temperature. © 1998 John Wiley & Sons, Ltd.
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  • 22
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 861-871 
    ISSN: 0268-2605
    Keywords: diorganotin ; Pyrimidine ; complex ; Mössbauer ; IR ; NMR ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complexes formed between the diorganotin(IV) moieties, R2Sn(IV), and the ligand 2-mercaptopyrimidine, (H)SPym, were investigated. Complexes R2SnHal(SPym) and R2Sn(SPym)2 [R = Me, iPr, nBu, iBu, tBu, cyclohexyl(Cy), Ph] were synthesized, and characterized by elemental analysis. In the solid state, chelation of SPym through S and N donors was established by IR spectroscopy, and the nature of the environment of tin centers was investigated by 119Sn Mössbauer spectroscopy. From the dynamics of 119Sn nuclei determined by variable-temperature measurements on representative compounds [Me2SnCl(SPym) and Cy2SnBr(SPym)], as well as by point-charge model treatment of nuclear quadrupole splitting parameters, it was inferred that Me2SnCl-­(SPym) may assume a trans-Me2 octahedral coordination geometry around tin in a monodimensional polymer, or a monomeric trigonal-bipyramidal structure (distorted). The latter type of structure was assigned to the other R2SnHal(SPym) species, while R2Sn(SPym)2 complexes assume a trans-octahedral, or skew trapezoidal, tin environment. In CHCl3-CDCl3 solutions, monomeric species occur (according to vapor-pressure osmometry), where 1H and 13C NMR spectroscopic parameters of SPym indicate the persistence of Sn chelation by S and N donor atoms. The Me2SnCl(SPym) species assume trigonal-bipyramidal structures with a chelating SPym ligand, in CDCl3 and C2H5OH solutions, according to the coupling constants 1J(119Sn,13C), as well as IR and 119Sn Mössbauer spectroscopic data. 119Sn NMR parameters fully correspond with data for the homologous complexes with 2-mercaptopyridine. Copyright © 1998 John Wiley & Sons, Ltd.
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  • 23
    ISSN: 0268-2605
    Keywords: platinum compound antileukaemic ; cytotoxic ; DNA ; thiosemicarbazone ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: p-Isopropylbenzaldehyde thiosemicarbazone (p-is.TSCN) (1) reacts with [Pt(µ-Cl)(η3-C4H7)]2 to form a dinuclear [Pt(µ-Cl)(p-is.TSCN)]2 complex (2) and a cyclometallated cluster [Pt(p-is.TSCN)]4 (3). Biological testing of these complexes against HL-60 and U-937 human leukemic cells suggest that complexes 2 and 3 may be endowed with important cytotoxic activity properties since they exhibit IC50 values (50% inhibition of cell growth) in the micromolar range, as does the clinically used drug cisplatin (cis-DDP). Analysis of the interaction of compounds 2 and 3 with DNA indicates that the kinetics of DNA platination due to compounds 2 and 3 is faster than that of cisplatin and that after 24 h of incubation most of the platinum centers are bound to DNA. Thus, it is likely that the cytotoxic activity displayed by compounds 2 and 3 may be correlated with their high level of DNA platination. Copyright © 1998 John Wiley & Sons, Ltd.
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  • 24
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 881-881 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 25
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 883-884 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 26
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    Applied Organometallic Chemistry 12 (1998), S. 591-599 
    ISSN: 0268-2605
    Keywords: arsenic speciation ; LC-ICP-MS ; validation ; urine samples ; background levels ; The Netherlands ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The method validation for the speciation of five arsenic species in urine samples by liquid chromatography hyphenated to inductively coupled plasma mass spectrometry is described. Arsenic species which are identified and quantified in urine samples are the anions of arsenic(III), arsenic(V), monomethylarsonic acid and dimethylarsinic acid, and the cationic arsenobetaine. Detection limits were obtained in the range 0.3-0.4 μg As l-1 while the repeatability was in the range 3-4% (RSD) for concentrations above five times the detection limit. Urine samples could be analysed directly after a ten-fold dilution step. Arsenic compound concentrations were determined in urine samples from a volunteer who consumed a portion of tuna fish high in arsenobetaine. It was found that arsenobetaine was excreted rapidly via the urine with maximum concentrations after 12 h. Nearly complete arsenobetaine excretion was reached after 48 h. Background levels of arsenic compounds were determined in 61 urine samples from non-exposed inhabitants of The Netherlands. © 1998 John Wiley & Sons, Ltd.
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  • 27
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    Applied Organometallic Chemistry 12 (1998), S. 613-620 
    ISSN: 0268-2605
    Keywords: manganese oxides ; montmorillonite ; kaolinite ; mercury(II) ; methylation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of freshwater sediment components such as kaolinite, montmorillonite and birnessite (δ-MnO2) on the biomethylation of mercury(II) in a synthetic growth medium (M-IIY) were assessed. Additions of kaolinite or montmorillonite to media containing mercuriC nitrate [Hg(NO3)2; 12 μg Hg ml-1] had no significant effect on either bacterial growth or the production of methylmercury (CH3Hg+). However, whereas the addition of birnessite resulted in only a small (ca 4%) increase in bacterial growth, it also produced a significant decrease (ca 50%) in the production of CH3Hg+. Further, it was demonstrated that, with the exception of kaolinite, adsorption of mercury(II) onto the sediment components before they were added to the M-IIY medium decreased its bioavailability, i.e., the amounts of CH3Hg+ produced from the adsorbed mercury(II) were significantly lower than those produced from equivalent concentrations of Hg(NO3)2 in the absence of the mineral colloids. In the case of montmorillonite, CH3Hg+ production was decreased by 21% relative to the control system. Most striking was the case of birnessite, in which no CH3Hg+ was detected after a 25 h incubation period and only very small quantities of CH3Hg+ (3-7 ng l-1) were present in the medium after 336 h. These data demonstrate that mineral colloids common in freshwater sediments significantly influence the extent of biomethylation of mercury(II) adsorbed on their surfaces. Birnessite, in particular, is a very effective inhibitor of the biomethylation of surface-bound mercury(II). Therefore, it may be possible to reduce the severity of mercury pollution in some aquatic environments by adding a reactive manganese oxide, such as birnessite, to the system and thereby to inhibit the transformation (methylation) of inorganic mercury(II) into the much more toxic CH3Hg+ species. © 1998 John Wiley & Sons, Ltd.
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  • 28
    ISSN: 0268-2605
    Keywords: surfactants ; carbohydrate ; carbosilane ; silane ; wetting ; surface tension ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of carbohydrate surfactants bearing carbosilane, silane, polysilane and non-permethylated siloxane moieties is described. These surfactants consist of three structural elements: (1) a silicon-containing moiety, (2) a spacer and (3) a carbohydrate unit. Additionally two different types of mixed structures have been synthesized: (a) single-chained carbosilane-siloxane surfactants and (b) double-chained combinations of carbo- silanes, silanes and siloxanes. The wetting behaviour of the key intermediates, the allyl glycidyl derivatives, has been investigated by static surface tension (γlv, σ) and wetting tension (γsv-γsl, α) measurements on a non-polar perfluorinated surface (FEP® plate). The contact angles obtained for these pure liquids are not a linear function of the surface tension but depend on the polarity of the substructures. © 1998 John Wiley & Sons, Ltd.
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  • 29
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    Applied Organometallic Chemistry 12 (1998), S. 67-75 
    ISSN: 0268-2605
    Keywords: organotin ; tributyltin ; tributyltin oxide ; tetrabutyltin ; degradation ; bioassay ; bioindicator ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The growth response of the alga Chlorella kessleri and the euglenoid Euglena gracilis has been studied as a model system to determine the effects of a tin salt (SnCl4·5H2O) and of some organotin (OT) derivatives, namely tetrabutyltin (TeBT), tributyltin (TBT) and tributyltin oxide (TBTO). Abiotic degradation was studied as well. Cells were exposed to a toxicity series (0-50 μg/mL-1) for the four chemicals in seven-day bioassays. Both microorganisms are tolerant of the inorganic salt, but growth inhibition was significant for all OT compounds, and especially large for TBT and TBTO. Although C. kessleri and E. gracilis are known to be tolerant towards metals and organic chemicals, the present results show that both are sensitive to organotin compounds: the inhibition of the growth was greater for C. kessleri. © 1998 John Wiley & Sons, Ltd.
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  • 30
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    Applied Organometallic Chemistry 12 (1998), S. 189-199 
    ISSN: 0268-2605
    Keywords: single-source precursor ; tetrakis(diethylamido)chromium ; pyrolysis mechanism ; MOCVD ; low-temperature deposition ; chromium carbonitride thin films ; hard metallurgical coatings ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amorphous chromium carbonitride coatings with a low nitrogen content (3-8 at%) were deposited by low-pressure MOCVD in the temperature range 573-793 K using Cr(NEt2)4 as single-source precursor. This poor nitrogen incorporation is in agreement with the trends predicted by thermochemical calculations. XPS data, resistivity measurements and annealing experiments suggest that the films grown at 573 K are contaminated by organic species due to incomplete elimination of the ligands. The films deposited at higher temperature crystallize upon annealing at 873 K to form an orthorhombic ternary chromium carbonitride phase. The major volatile by-products of the MOCVD reaction were analyzed by 1H and 13C NMR. Their amount and the quasi-equimolar EtN=CHMe/HNEt2 ratio suggest that most of the NEt2 ligands are removed by a stepwise mechanism which probably occurs with other diethylamido complexes of transition metals when they are used as single-source precursors in MOCVD. The incorporation of the metalloid elements in the film is discussed in comparison with recent literature data. © 1998 John Wiley & Sons, Ltd.
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  • 31
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    Applied Organometallic Chemistry 12 (1998), S. 221-236 
    ISSN: 0268-2605
    Keywords: MOCVD ; barium ; liquid delivery ; mixed-metal species ; aerosol-assisted CVD ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conventional MOCVD techniques require molecules displaying volatility and constant vapor pressure. Metal oxide precursors, i.e., β-diketonates, or classical or functionalized metal alkoxides are mostly solids. The various approaches used to tailor volatility are discussed with barium derivatives as an example. The relationships between sublimation temperature and molecular weight suggest that volatility can be optimized on the basis of molecular weight.   Aerosol-assisted CVD (AACVD) can use a larger range of precursors since volatility is no longer crucial. The solvent is an undesired ballast in a CVD process. High solubility of the precursors in the selected solvent is thus desirable. ‘Stability’ here includes the absence of precipitation which would change the stoichiometry of the feed solution for multicomponent oxides. Precipitation is often promoted by hydrolysis; stability toward moisture is thus desirable. The use of mixtures of precursors based on different ligands (β-diketonates, β-ketoesterates, alkoxides) can lead to ligand exchange reactions giving homometallic species, sometimes of low solubility, or mixed-metal species by self-assembly, thus improving solubility and stability toward moisture. These aspects are illustrated in compositions related to high-Tc superconductors. Novel copper, yttrium, cerum(IV), barium-copper, yttrium-copper and praseodynium-copper species are reported. © 1998 John Wiley & Sons, Ltd.
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  • 32
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 33
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    Applied Organometallic Chemistry 12 (1998), S. 296-296 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 34
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    Applied Organometallic Chemistry 12 (1998), S. 237-241 
    ISSN: 0268-2605
    Keywords: tin ; iodomethane ; solubilization ; methyltin species ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dissolution of tin metal by iodomethane-water mixtures has been studied and the influence of several parameters on both the extent and rate of reaction investigated. The rate-determining step shows a pseudo-first-order dependence on iodomethane (CH3I). The reaction is strongly dependent upon both water and oxygen. The activation energy of only 16 kJ mol-1 is interpreted in terms of a facile bond-breaking and making process at the metal surface, generating methyltin species. Analysis by hydride generation and GC-AA confirmed the formation of methylated species ranging from monomethyl- to tetramethyl-tin; inorganic tin (from hydrolysis) was the major form, however. These findings are similar to those made earlier by us on the solubilization of arsenic from GaAs by alkyl halide-water mixtures, and a similar multi-step scheme is proposed. © 1998 John Wiley & Sons, Ltd.
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  • 35
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    Applied Organometallic Chemistry 12 (1998), S. 257-264 
    ISSN: 0268-2605
    Keywords: Rochow reaction ; cesium chloride ; rubidium chloride ; silicon impurities ; action of promoters ; scanning electron microscopy (SEM) ; energy-dispersive X-ray spectroscopy (EDX) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cesium chloride- and rubidium chloride-promoted Rochow contact masses based on both technical-grade and highly pure silicon have been investigated in the Rochow reaction and by REM/EDX surface analysis. The alkali-salt promoters seem to act analogously to the well-known zinc promoter, by localizing the reaction to distinct reactive areas and keeping free the surface area for the reaction, probably for the formation of catalytically active Cu-Si surface species. The alkali salts exhibited their promoting action only in combination with the impurities within the technical-grade silicon. Otherwise, they acted as blocking poisons. The promoter action of alkali chlorides in contact masses based on technical-grade silicon is possibly connected with the formation of salt melts, containing alkali chlorides and impurities. These melts, analogously to zinc chloride, could dissolve oxidic impurities from the silicon surface which otherwise would enhance the blocking of potentially active surface by extensive copper deposition. © 1998 John Wiley & Sons, Ltd.
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  • 36
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    Applied Organometallic Chemistry 12 (1998), S. 277-284 
    ISSN: 0268-2605
    Keywords: carboxylation ; methane ; carbon monoxide ; ytterbium(III) acetate ; manganese(II) acetate ; sodium hypochlorite ; acetic acid ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method of synthesis of acetic acid in water has been developed from the carboxylation of methane with carbon monoxide using lanthanide catalysts. Ytterbium(III) acetate has been found to be the most active catalyst among the compounds of the lanthanide series in the carboxylation reaction of methane with carbon monoxide. Sodium hypochlorite or hydrogen peroxide was used as the oxidant in this reaction. Sodium hypochlorite exhibited more favorable activity than hydrogen peroxide in the reaction. The catalytic activity was improved by the addition of transition-metal salts such as manganese(II) acetate. The best result has been found at a ratio of manganese(II) acetate to ytterbium(III) acetate of 1:10. The optimum reaction conditions (reaction temperature, 40 °C; time, 20 h; methane, 20 atm; carbon monoxide, 5 atm) have been obtained. © 1998 John Wiley & Sons, Ltd.
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  • 37
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    Applied Organometallic Chemistry 12 (1998), S. 299-301 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 38
    ISSN: 0268-2605
    Keywords: magnetization reversal ; iron oxide particles ; SQUID ; atomic force microscopy ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report first measurements of the magnetization reversal of monodisperse 30 nm and 50 nm ferromagnetic Fe3O4 particles. These particles are produced in a carrier gas as an aerosol by spray pyrolysis. After production and size selection, they are precipitated on a silicon chip with a niobium SQUID (superconducting quantum interference device) incorporated on its surface. By changing a magnetic field in the plane of the SQUID, we can measure the magnetization reversal of the particles by the flux they induce into the SQUID. The angular dependence of this reversal is determined by rotating the magnetic field around the SQUID. Scanning electron microscope (SEM) images have confirmed the particle size and revealed the position of the collected particles. If the particle concentration is too high, we cannot detect changes in the magnetic moment of a single particle, but measure the magnetic properties of the whole assembly. If only a few particles are found on the SQUID loop the angular dependence of the magnetic reversal of a single particle can be measured; this result is compared with a simple model of magnetization reversal. © 1998 John Wiley & Sons, Ltd.
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  • 39
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    Applied Organometallic Chemistry 12 (1998), S. 520-520 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 40
    ISSN: 0268-2605
    Keywords: organotin ; N-(2-pyridylmethylene)arylamines ; IR ; NMR ; Mössbauer ; mutagenicity ; sister chromatid exchange ; cell cycle delay ; bone-marrow cells ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diorganotin(IV) dichloride complexes of the type R2SnCl2·L (R = methyl, ethyl, vinyl, t-butyl, n-butyl or phenyl; L = N-(2-pyridylmethylene)arylamine) have been synthesized and characterized on the basis of IR, NMR and 119Sn Mössbauer studies. Investigation of the complexes indicated that N-(2-pyridylmethylene)arylamines form distorted trans-octahedral complexes with R2SnCl2 similar to the well-known R2SnCl2·L. Cytogenetic toxicology testing has been performed for Et2SnCl2·L4 [L4 = N-(2-pyridylmethylene)-4-toluidine] in mouse bone-marrow cells in vivo since such testing is a regulatory requirement before new drugs are released. This tin compound induced delay in cell-cycle kinetics and sister chromatid exchanges (SCEs) significantly. The effect of Et2SnCl2·L4 was greater when endogenous glutathione (GSH) was depleted by buthionine sulphoximine (BSO). It seems that Et2SnCl2·L4 induces SCEs due to formation of adduct by binding on DNA which could interfere in DNA synthesis and cause delay in cell proliferation. Depletion of GSH could reduce the shielding effect of GSH on chromatin and allows more Et2SnCl2·L4 to bind on DNA. © 1998 John Wiley & Sons, Ltd.
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  • 41
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    Applied Organometallic Chemistry 12 (1998), S. 801-807 
    ISSN: 0268-2605
    Keywords: metal-containing vinylic monomers ; vinylbenzoyl complexes ; cinnamoyl complexes ; tungsten-olefin monomers ; iron-olefin monomers ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of metal-containing vinylic monomers of the type LnM(COC6H4CH=CH2) and LnM (COCH=CHC6H5) [LnM = (η5-C5H5)Fe(CO)2, (η5-C5Me5)Fe(CO)2 and (η5-C5H5)W(CO)3] were prepared by the reaction of the appropriate metal anion with either 4-vinylbenzoyl chloride or cinnamoyl chloride. (η5-C5H5)(CO)2FeCOCH=CH2 was prepared by the reaction of Na[(η5-C5H5)Fe(CO)2] and acryloyl chloride, whereas the compound (η5-C5H5)(CO)2Fe(C6H4CH=CH2) was prepared via a transmetallation reaction using a palladium catalyst. All compounds were fully characterized using FTIR, 1H and 13C NMR spectroscopy and mass spectrometry. Copyright © 1998 John Wiley & Sons, Ltd.
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  • 42
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    Applied Organometallic Chemistry 12 (1998), S. 793-799 
    ISSN: 0268-2605
    Keywords: anticancer ; antineoplastic ; ferrocene/ferricenium ; biological redox ; free radical ; polyaspartamide ; tumor ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ferrocene/ferricenium redox system plays a significant role in biological oxidation, reduction and free-radical reactions. Of particular interest are the findings of earlier investigations which showed certain water-soluble ferricenium salts to possess appreciable antiproliferative activity against various murine tumor lines and a xenografted human colorectal adenocarcinoma. Solubility in water, a prerequisite for efficacious transport and dissipation in central circulation, was then proposed as a principal requirement for the ferrocene complex system to exert antineoplastic activity irrespective of the oxidation state in which it is administered. In order to shed more light on this question, we decided to investigate the antiproliferative properties of polymer-ferrocene conjugates containing the metal complex in the non-oxidized (ferrocene) form while fulfilling the critical requirement of water solubility. To this end, five selected, water-soluble conjugates, synthesized by reversible coupling of 4-ferrocenylbutanoic acid to variously structured polyaspartamides featuring pendant primary amino groups as coupling sites, were tested in vitro against cultured HeLa cells at concentrations up to 50 µg Fe ml-1. Optimal antiproliferative activities, with IC50 in the range of 2-7 µg Fe ml-1, were determined for three compounds possessing tertiary-amine functions susceptible to protonation at physiological pH. Lower activities (IC50 = 45-60 µg Fe ml-1) were demonstrated for two poly(ethylene oxide)-containing conjugates. However, no reasonable structure-performance relationships can be derived at this stage from the small number of compounds tested. Copyright © 1998 John Wiley & Sons, Ltd.
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  • 43
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    Applied Organometallic Chemistry 12 (1998), S. 880-880 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 44
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    Applied Organometallic Chemistry 12 (1998), S. 439-447 
    ISSN: 0268-2605
    Keywords: high-performance liquid chromatography ; hydride generation ; atomic fluorescence spectrometry ; photo-oxidation ; arsenic speciation ; human urine ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potential of coupling anion-exchange high-performance liquid chromatography, hydride generation and atomic fluorescence spectrometry (HPLC-HG-AFS) for arsenic speciation is considered. The effects of hydrochloric acid and sodium tetrahydroborate concentrations on signal-to-background ratio, as well as argon and hydrogen flow rates, were investigated. Detection limits for arsenite, dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and arsenate were 0.17, 0.45, 0.30 and 0.38 μg l-1, respectively, using a 20-μl loop. Linearity ranges were 0.1-500 ng for As(III) and MMA (as arsenic), and 0.1-800 ng for DMA and As(V) (as arsenic). Arsenobetaine (AsB) was also determined by introducing an on-line photo-oxidation step after the chromatographic separation. In this case the limits of detection and linear ranges for the different species studied were similar to the values obtained previously for As(V). The technique was tested with a human urine reference material and a volunteer's sample. © 1998 John Wiley & Sons, Ltd.
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  • 45
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    Applied Organometallic Chemistry 12 (1998), S. 880-881 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
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  • 46
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    Applied Organometallic Chemistry 12 (1998), S. 521-521 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 47
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    Applied Organometallic Chemistry 12 (1998), S. 469-474 
    ISSN: 0268-2605
    Keywords: asymmetric catalysis ; diethylzinc ; alkylation ; chiral heterocyclic alcohols ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The asymmetric alkylation with diethylzinc of five heterocyclic aldehydes and benzaldehyde (for comparison) has been studied in the presence of two optically active amino alcohols: (S)-2-amino-1-butanol (AB) and (1S,2R)-N,N-dibutylnorephedrine (DBNE). A number of chiral (hetero)aromatic secondary alcohols were synthesized in high yields (95-98%) with enantioselectivity up to 92% enantiomeric excess (ee) in the presence of DBNE catalyst. Optically active thienyl and 4-pyridyl derivatives were prepared for the first time by catalytic asymmetric alkylation. The influence of the amount of DBNE on the enantioselectivity was investigated. In contrast to benzaldehyde, 2-furan- and 2-thiophene-carbaldehydes, in the case of 3- and 4-pyridinecarbaldehydes the ee values depend directly on the catalyst concentration. © 1998 John Wiley & Sons, Ltd.
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  • 48
    ISSN: 0268-2605
    Keywords: HPLC-ICP-MS ; cetaceans ; pinnipeds ; arsenic ; arsenobetaine ; arsenocholine ; whales ; seals ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Total arsenic concentrations and the concentrations of individual arsenic compounds were determined in liver samples of pinnipeds [nine ringed seals (Phoca hispida), one bearded seal (Erginathus barbatus)] and cetaceans [two pilot whales (Globicephalus melas), one beluga whale (Deliphinapterus leucus)]. Total arsenic concentrations ranged from 0.167 to 2.40 mg As kg-1 wet mass. The arsenic compounds extracted from the liver samples with a methanol/water mixture (9:1, v/v) were identified and quantified by anion- and cation-exchange chromatography. An ICP-MS equipped with a hydraulic high-pressure nebulizer served as the arsenic-specific detector. Arsenobetaine (0.052-1.67 mg As kg-1 wet mass) was the predominant arsenic compound in all the liver samples. Arsenocholine was present in all livers (0.005-0.044 mg As kg-1 wet mass). The tetramethylarsonium cation was detected in all pinnipeds (〈0.009 to 0.043 mg As kg-1) but not in any of the cetaceans. The concentration of dimethylarsinic acid ranged from 〈 0.001 to 0.109 mg As kg-1 wet mass. Most of the concentrations for methylarsonic acid (〈0.001 to 0.025 mg As kg-1 wet mass) were below the detection limit. Arsenous acid and arsenic acid concentrations were below the detection limit of the method (0.001 mg As kg-1). An unknown arsenic compound was present in all liver samples at concentrations from 0.002-0.027 mg As kg-1. © 1998 John Wiley & Sons, Ltd.
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  • 49
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 50
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    Applied Organometallic Chemistry 12 (1998), S. 571-576 
    ISSN: 0268-2605
    Keywords: zerovalent metals ; bromoalkyltriphenylphosphonium bromides ; methylmercuric acetate ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aqueous solutions of bromoalkyltriphenylphosphonium bromides react with zerovalent metals, causing their dissolution. The reaction initially follows second-order kinetics, with the rate depending on both metal and bromide concentrations. Zerovalent metals similarly react with aqueous methylmercuric acetate and other dissolved organometals. © 1998 John Wiley & Sons, Ltd.
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  • 51
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 601-611 
    ISSN: 0268-2605
    Keywords: tributyltin ; triphenyltin ; bioavailability ; bioconcentration factors ; humic substances ; pH dependence ; speciation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bioconcentration of triphenyltin (TPT) and tributyltin (TBT) was studied in the freshwater organisms Daphnia magna (zooplankton), Chironomus riparius (sediment organism) and Thymallus thymallus (fish yolk-sac larvae). TPT bioconcentration factors (BCFs) at pH 8 were highest for Thymallus (2200), followed by Chironomus (680) and Daphnia (190). The differences could not be fully explained by different total lipid contents. Metabolism and lower bioconcentration were observed for TBT in Chironomus. The BCFs of both TBT and TPT were higher at pH 8 than at pH 5, but the difference was much less pronounced than predicted by the octanol-water partition model. This suggests that, besides the hydroxide species (TBTOH and TPTOH), the cations (TBT+ and TPT+) are also taken up by the organisms to some extent and that the octanol-water partition model underestimates the uptake of the charged species. Low concentrations of humic substances (HS) led to small reduction in the bioconcentration of TPT in Daphnia and Thymallus, and a significant reduction occurred at relatively high concentrations of HS (〉10 mg C l-1). The results of this study provide an important basis for future investigations aiming at a better understanding of the bioavailability and fate of TBT and TPT in freshwater ecosystems. © 1998 John Wiley & Sons, Ltd.
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  • 52
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 827-842 
    ISSN: 0268-2605
    Keywords: Scopulariopsis brevicaulis ; hydride generation ; antimony ; biomethylation ; biotransformation ; solid-phase extraction ; sudden infant death syndrome (SIDS) ; volatile antimony ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cultures of the fungus Scopulariopsis brevicaulis were grown in antimony-rich media. Although volatile compounds of other elements were readily detected in the culture headspace, volatile antimony compounds were formed irreproducibly and at only ultratrace levels. In order to monitor the media for nonvolatile methylantimony compounds, a method of sample preparation was developed, based on solid-phase extraction. This enabled the separation of large quantities of soluble inorganic antimony species from trace amounts of organoantimony compounds before speciation by HG-GC-AAS. By this methodology methylated antimony compounds were detected at concentrations of 0.8- 7.1 µg Sbl-1 in all media in which S. brevicaulis was grown in the presence of antimony(III) compounds. These methylantimony species were not detected in any of the nonliving or medium-only controls. Methylated compounds were not detected where S. brevicaulis was grown in the presence of antimony(V) compounds. This is the first study to show that antimony(III) compounds are biomethylated by S. brevicaulis under aerobic-only growth conditions. Copyright © 1998 John Wiley & Sons, Ltd.
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  • 53
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 873-876 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 54
    ISSN: 0268-2605
    Keywords: precursor ; ceramic ; thermolysis ; silicon ; carbodi-imide ; boron ; hydroboration ; plastic forming ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis, by two different reaction pathways, of boron-modified polysilylcarbodi-imides of general type {B[C2H4Si(R)NCN]3}n (R =­singly bonded organic ligand) and the plastic-forming and the thermal behavior of these polymers are described. Compounds {B[C2H4Si(R)NCN]3}n [2a, R = H; 2b, R = CH3; 2c, R = (NCN)0.5] can be obtained by treatment of the vinyl-substituted polysilylcarbodi-imides [(H2C=CH)(R)SiNCN]n [1a, R = H; 1b, R = CH3; 1c, R = (NCN)0.5] with borane dimethylsulfide BH3·S(CH3)2. The polysilylcarbodi-imides 1a-1c themselves are accessible via the reaction of vinyl-substituted chlorosilanes (H2C=CH)-­(R)SiCl2 with cyanamide H2N-C≡N in the presence of pyridine or by a non-oxide sol-gel process of vinylated chlorosilanes and bis(trimethylsilyl)carbodi-imide, (H3C)3SiN=C=NSi(CH3)3. In the second method for the synthesis of 2a-2c, hydroboration of vinyl-substituted chlorosilanes (H2C=CH)(R)SiCl2 with borane dimethylsulfide, borane trimethylamide or borane triethylamide to yield the tris[(chlorosilyl)ethyl]boranes B[C2H4Si(R)Cl2]3 (3a, R = H; 3b, R = CH3; 3c, R = Cl) is followed by treatment of the as-obtained compounds with bis(trimethylsilyl)carbodi-imide, which results in the formation of the hydroborated polysilylcarbodi-imides 2a-2c. The thermogravimetric behavior of the polymers 1a-1c and 2a-2c up to 2300°C is reported. It is shown that boron-modified polysilylcarbodi-imides are suitable precursors for the preparation of dense bulk ceramics. Therefore, the preparation of green bodies of the hydroborated polysilylcarbodi-imides 2a-2c by plastic forming (PF) is described. A series of experiments points to the fact that the microstructure of the as-obtained ceramic monoliths obtained by subsequent thermolysis of the plastic-formed green bodies is strongly influenced by the conditions during plastic forming. © 1998 John Wiley & Sons, Ltd.
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  • 55
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 675-680 
    ISSN: 0268-2605
    Keywords: polymer ; nanocomposites ; silicates ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymer nanocomposites, especially polymer-layered silicate (PLS) nanocomposites, represent a radical alternative to conventionally (macroscopically) filled polymers. Because of their nanometer-size dispersion, the nanocomposites exhibit markedly improved properties when compared with the pure polymers or conventional composites. These include increased modulus and strength, decreased gas permeability, increased solvent and heat resistance and decreased flammability. In addition to their potential applications, PLS nanocomposites are also unique model systems to study the structure and dynamics of polymers in confined environments. Using both delaminated and intercalated hybrids, the statics and dynamics of polymers confined over distances ranging from the radius of gyration of the polymer to the statistical segment length of the chains can be studied. © 1998 John Wiley & Sons, Ltd.
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  • 56
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 715-723 
    ISSN: 0268-2605
    Keywords: Cubic Silsesquioxanes ; interface ; materials ; hybrids ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cubic silsesquioxanes, [RSiO1.5]x, potentially offer access to organic/inorganic hybrids wherein the exact shape, size and mechanical properties of the inorganic component are perfectly defined. Furthermore, by tailoring the organic functionality bound to silicon, the inorganic/organic interface can also be perfectly defined. Finally, careful selection of the polymerizable groups in the organic moieties can provide good-to-excellent control of the crosslinked density or degree of polymerization of the resulting hybrid materials. Thus, cubic silsesquioxanes may be exceptional model materials for inorganic/organic hybrids. Methods of synthesizing cubes with liquid-crystalline and/or polymerizable organic moieties are described. Some thermal properties are discussed. The catalytic copolymerization of the octavinyldimethylsiloxy-functionalized cube with the octahydridodimethyl-­siloxy-functionalized cube to produce a material with well-defined microporosity and high surface area is described. © 1998 John Wiley & Sons, Ltd.
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  • 57
    ISSN: 0268-2605
    Keywords: polymer ; organocobalt ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rearrangement reaction of an organocobalt polymer with cobaltacyclopentadiene moieties in the main chain (1) was carried out to yield a­new polymer bearing (η5-cyclopentadienyl) (η4-­cyclobutadiene)cobalt moieties in the main chain (2). For instance, a polymer (2) containing pure η4-cyclobutadienecobalt units was obtained as a yellow powder in 79% yield by the reaction of 1 in tetrahydrofuran (THF) at 110 °C for 1 h in a sealed tube. The polymer (2) obtained was soluble in organic solvents such as chloroform, THF and N,N-dimethylformamide and was quite stable under air. It showed good thermal stability and a weight loss of 5% was observed at 482 °C by thermogravimetric analysis (TGA). On the other hand, displacement of the triphenylphosphine ligands on the main chain of the organocobalt polymer (1), without rearrangement of the cobaltacyclopentadiene rings, was observed when the reaction was carried out in the presence of appropriate ligands such as P(n-Bu)3. The resulting ligand-exchanged polymer showed different properties in comparison with 1. For instance a polymer bearing tri-n-octylphosphine is soluble in n-hexane, which is a poor solvent for 1. © 1998 John Wiley & Sons, Ltd.
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  • 58
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 743-748 
    ISSN: 0268-2605
    Keywords: carbon black ; surface grafting of polymer ; polymer radical ; radical trapping ; azo-polymer ; peroxy-polymer ; electrical resistance ; poly(ethylene oxide) ; poly(ethylene imine) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The grafting of polymers onto a carbon black surface based on the trapping of polymer radicals by polycondensed aromatic rings of the surface was investigated. It was found that polymer radicals formed by the thermal decomposition of azo-polymer, peroxy-polymer and 2,2,6,6-tetramethylpiperidinyl-1-oxy-terminated polymer are successfully captured by a carbon black surface to give the corresponding polymer-grafted carbon blacks. The grafting of polymers onto carbon black was also achieved by the trapping of polymer radicals formed by the redox reaction of ceric ions with polymers having hydroxyl groups. It was concluded that surface grafting of polymers onto carbon black is effective when there are few functional groups. The electrical resistance of poly(ethylene oxide) (PEO)-grafted carbon black thus obtained is increased drastically to about 104-105 times the initial resistance at the melting point of PEO. This may be due to a widening of the gaps between the carbon black particles by melting of PEO. In addition, it was found that the electrical resistance of a crystalline poly(ethylene imine) (PEI)-grafted carbon black drastically increased to 103-104 times the initial resistance in methanol, ethanol and water vapor, but hardly any change in electrical resistance was observed in n-hexane or toluene vapor. These results suggest the possibility of detecting a slight change in the crystalline structure of PEI upon absorption of solvent vapor as a large increase in the electrical resistance of the polymer-grafted carbon black. © 1998 John Wiley & Sons, Ltd.
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  • 59
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 681-693 
    ISSN: 0268-2605
    Keywords: ceramics ; preceramic polymers ; SiNCB composites ; boron nitride ; boron ; silicon ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Our recent work directed at the design, synthesis, characterization and applications of new types of polyborazylene and polyborosilazane polymers is reviewed with a focus on the use of these polymers as processable precursors to BN and SiNCB composites. A design strategy based on the controlled functionalization of preformed polymers with pendant groups of suitable compositions and crosslinking properties has been employed to yield second-generation dipentylamine-polyborazylene (DPA) and pinacolborane-hydridopolysilazane (PIN-HPZ) polymers, which, unlike the parent polyborazylene (PB) and the borazine-hydridopolysilazane (B-HPZ) polymers, are stable as melts and can be easily melt-spun into polymer fibers. Subsequent pyrolyses of these polymer fibers then provide excellent routes to BN and SiNCB ceramic fibers. © 1998 John Wiley & Sons, Ltd.
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  • 60
    ISSN: 0268-2605
    Keywords: X ray structure ; triphenyltin ; p-ethoxybenzoic acid ; acetylsalicylic acid ; phthalic acid ; salicylaldehydato ; polymer ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triphenyltin(IV) compounds of p-ethoxybenzoic acid and acetylsalicylic acid contain molecular units with Sn-O bonds and distorted tetrahedral tin centers. The phthalic acid derivative contains two four-coordinate tin atoms between which the phthalic acid unit effectively forms a bridge. The salicylaldehydato compound is polymeric with trigonal bipyramidal tin centers in which the phenyl groups take equatorial positions. The polymerization occurs via the aldehyde oxygen atom bonding to a neighboring tin atom. © 1998 John Wiley & Sons, Ltd.
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  • 61
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 25-30 
    ISSN: 0268-2605
    Keywords: adduct ; carboxylate ; Ceratocystis ulmi ; Dutch elm disease ; far-infrared spectroscopy ; fungicide ; Mossbauer spectroscopy ; organotins ; QSAR ; thiazolidin-4-ones ; triphenyltin ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the interest of developing a more effective fungicide to combat Dutch elm disease, our laboratories have synthesized several triphenyltin carboxylates and some 1:1 addition compounds of triphenyltin chloride using 2,3-disubstituted thiazolidin-4-ones as the ligand and screened them in vitro against Ceratocystis ulmi, the causative agent of Dutch elm disease, using a shake culture method. Elemental analyses and spectroscopic data indicate that the structures of the carboxy- lates in the solid state are monomeric with a tetrahedral tin atom with the exception of the furan-2-carboxylic acid derivative, which was found to be polymeric. The triphenyltin chloride adducts are trigonal-bipyramidal with the three phenyl groups in the equatorial plane. Far-infrared data indicate that the three phenyl groups are not co-planar. Screening results for both series of organotins indicate that these two classes of compounds are effective inhibitors of Ceratocystis ulmi, with the adducts having a higher activity. The furan-2-carboxylic acid derivative has a markedly decreased activity compared with the other carboxylates and this is attributed to its polymeric structure. © 1998 John Wiley & Sons, Ltd.
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  • 62
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 78-78 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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