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  • 1995-1999  (142)
  • 1998  (142)
  • Industrial Chemistry and Chemical Engineering  (141)
  • Engineering General
  • 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.
    Type of Medium: Electronic Resource
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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: Nickel-σ-organyl complexes ; dispersed atomic Ni(0) ; Ni(I) ions ; silica ; EPR ; FMR ; spectrum calculation ; strain ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dispersed atomic nickel(0) is formed during the reaction of the nickel-σ-organyl complexes with silanol groups at temperatures below 373 K. That nickel is oxidized to Ni(I) by protons of the silanol groups in a consecutive step. The Ni(I) portion amounts to about 70% w/w of the Ni used. Six different Ni(I) species are detected by electron paramagnetic resonance. They are stabilized by interaction with the silica surface and the organic moieties; they act as anchor ions for the Ni(0) atoms. Ni(0) crystallites stabilized in this way are about 0.5 nm in diameter after a treatment at 373 K. The influence of the Ni(I) ions on the collective, magnetic properties of the clusters is revealed by calculation of ferromagnetic resonance (FMR) spectra using the independent-grain approach according to Schlömann and Kotyukov. A strain of about 10 GPa is brought about in the nickel crystallites by the interaction with Ni(I) ions. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
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  • 4
    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.
    Additional Material: 3 Ill.
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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 467-467 
    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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  • 7
    ISSN: 0268-2605
    Keywords: fungicidal activity ; Ceratocystis ulmi ; triphenyltin(IV) ; tributyltin(IV) ; phenolic bridge ; carboxylate bridge ; polymers ; trigonal bipyramidal structures ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methods of synthesis, elemental analysis, IR and NMR spectroscopic data and fungicidal activity against Ceratocystis ulmi are reported for a series of triorganotin esters of N-arylidene-ω-amino acids of general formula R3SnOCO(CH2)nN = CHAr (R = Ph, n-Bu; Ar = 2-HOC6H4, 2-HOC10H6; n = 1, 2, 3 and 5). The crystal structures for two of the compounds, tributyltin N-2-hydroxynaphthalidene glycinate (1) and tributyltin N-2-hydroxynaphthalidene-β-alaninate (2), have been determined. Although both of these compounds have a trans-R3SnO2 structure, in compound 1 the carboxylate group is monodentate and the fifth coordination position around the tin atom is taken up by a coordinated phenolic group, whereas in 2 the carboxylate group is bridging. These two examples thus correspond to the two different structures reported for trans-R3SnO2 complexes. Both compounds were found to be active against Ceratocystis ulmi, but there was no significant difference in their levels of biological activity against this particular fungus. Apart from compound 1, the other tributyltin compounds reported are believed to adopt the carboxylate bridging mode shown by compound (2).Crystal data: for 1, crystals monoclinic, space group P21/c, a = 12.9435(11) Å, b = 13.5769(10) Å, c = 15.7715(12) Å, β = 108.919(6)°, Z = 4, Rf = 0.046 and Rw = 0.058 for 1448 significant reflections; for 2, crystals monoclinic, space group C 2/c,a = 24.588(14) Å, b = 9.733(3) Å, c = 27.611(12) Å,β = 113.49(4)°, Z = 8, Rf = 0.053 and Rw = 0.069 for 3822 significant reflections. © 1998 John Wiley & Sons, Ltd.
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  • 8
    ISSN: 0268-2605
    Keywords: density functional calculation ; binuclear metal carbonyl ; Cr2(CO)6+ ; laser ablation ; molecular beam ; optimized structures ; dissociation energy ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Density functional calculations have been made on a binuclear metal carbonyl ion Cr2(CO)6+ found in our laser ablation-molecular beam (LAMB) experiment. Optimized structures are calculated for three different conformations: T33 of D3d symmetry with three terminal carbonyl groups on each chromium atom, B2T22 of D2h symmetry with two bridging carbonyl groups and two terminal carbonyl groups on each chromium atom, and B4T11 of D4h symmetry with four bridging carbonyl groups and one terminal carbonyl group on each chromium atom. The most stable conformation is T33 which is 36.76 and 286.44 kJ mol-1 lower in energy than B2T22 and B4T11, respectively. The difference of conformation exerts a significant influence on the internuclear distance between chromium and the carbon of terminal CO, but hardly on the Cr-Cr bond length. For B2T22 and B4T11, longer C-O distances for bridging carbonyls compared with those for terminal ones indicate effective π*-back donation from the chromium atom to the bridging carbonyl groups. Furthermore, the relative abundance of Cr2(CO)n+ (n = 0-6) observed in our previous experimental study can be explained qualitatively by comparison of the excess energy produced in the formation of a Cr+-Cr bond with the CO dissociation energy of Cr2(CO)6+. © 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. 467-468 
    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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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 468-468 
    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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  • 11
    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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  • 12
    ISSN: 0268-2605
    Keywords: metal clusters ; quantum-size effect ; nanostructures ; size effects ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Meta-cluster compounds can be exploited advantageously to study the evolution, with increasing size of the molecules of the physical properties of metal clusters from molecular to bulk-metal behavior. The metal-cluster molecules are well-defined, stoichiometric, chemical compounds. The molecules consist of a metal core of a variable number of atoms, surrounded by a shell of ligand atoms or molecules. Depending on the compound, the type of metal atom may be varied, whereas the core size can be changed from a few up to several thousands of atoms. Accordingly, these materials provide excellent model systems for monodisperse metal particles, embedded in a dielectric matrix, and can be investigated by the well-known experimental techniques of solid-state physics. © 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. 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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  • 14
    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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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    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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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    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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  • 17
    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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  • 18
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 878-878 
    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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  • 20
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 884-884 
    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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  • 21
    Electronic Resource
    Electronic Resource
    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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  • 22
    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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  • 23
    ISSN: 0268-2605
    Keywords: methylmercury ; analysis ; HPLC- ICP MS ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel technique has been developed for the determination of trace amounts of methylmercury in various sample matrices. The newly developed HPLC method makes it possible to separate methylmercury and inorganic mercury with ultrasonic nebulization and detection by ICP MS for different mercury isotopic masses. The isotope-specific detection allows the application of the species-specific isotope addition method for the determination of methylmercury with a correction for artifact formation. The well-known water-vapour distillation method was used in combination with an enriched stable inorganic mercury isotope (200Hg2+) for the separation of methylmercury from various matrices. The subsequent determination of CH3 - 200Hg+ generated from 200Hg2+ was used in the correction for artifact formation during sample preparation. In comparison with a previously developed HPLC coupling technique with HPF-HHPN (high-performance flow/­hydraulic high-pressure nebulization), the stability of the detection procedure was improved considerably. The limit of detection (S/N = 3) for methylmercury was calculated to be about 0.015 μg kg-1. © 1998 John Wiley & Sons, Ltd.
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  • 24
    ISSN: 0268-2605
    Keywords: methylmercury ; solid-phase microextraction ; gas chromatography-atomic fluorescence ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analytical method is described for methylmercury determination in fish and aqueous samples using solid-phase microextraction (SPME) followed by gas chromatography-atomic fluorescence spectrometry (GC-AFS). The procedure involves aqueous-phase derivatization of methylmercury species with sodium tetraethylborate in a sample vial and subsequent extraction with a silica fiber coated with poly-­(dimethylsiloxane). The mercury derivatives are desorbed in the splitless injection port of a gas chromatograph and subsequently analyzed by GC-AFS. The headspace SPME procedure is used and parameters affecting the extraction, adsorption and desorption are evaluated. Results for methylmercury analysis in standard reference material (DORM-2) and fish samples are presented. © 1998 John Wiley & Sons, Ltd.
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  • 25
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    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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  • 26
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 659-666 
    ISSN: 0268-2605
    Keywords: polymers ; polyphosphazenes ; synthesis ; surfaces ; surface reactions ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The macromolecular substitution approach for the synthesis of polyphosphazenes provides access to many different polymers. However, it precludes the use of reagents that contain two or more functional groups because such compounds would cause extensive crosslinking of the chains. This presents a problem because many of the uses for which polyphosphazenes seem ideally suited require the presence of -OH, -COOH, -NH2, -SO3H, -PR2 and other functional units in the side-chain structure. We have developed two approaches to introduce such active sites: (1) protection-deprotection reactions; and (2) direct reactions of active reagents with the organic side-groups of non-functional poly(organophosphazenes). These methods have been applied both at the molecular level and in the form of reactions carried out only at polymer surfaces. The resultant polymers have special properties that are valuable in the micro-encapsulation of sensitive biological agents; in the formation of hydrophobic, hydrophilic, or adhesive surfaces; in crosslinking reactions; and in the development of solid polymer electrolytes, bio-erodible polymers, pH-triggered hydrogels, polymer blends and interpenetrating polymer networks. Overall, more than 700 different polyphosphazenes are now known, and a large number of these are functional macromolecules targeted for specific property combinations and uses. © 1998 John Wiley & Sons, Ltd.
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  • 27
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 707-713 
    ISSN: 0268-2605
    Keywords: polyhedral oligomeric silsesquioxane ; hybrid ; thermoplastic ; polymer ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A diverse and entirely new class of monomer and polymer technology based on polyhedral oligomeric silsesquioxane (POSS) reagents has been developed. POSS reagents are unique in that they are physically large (approx. 15 Å diameter and 1000 amu) and are composed of a robust silicon-oxygen framework that can be easily functionalized with a variety of organic substituents. Appropriate functionalization of POSS cages allows for their incorporation into traditional thermoplastic resins without modification of existing manufacturing processes. The incorporation of POSS segments into linear copolymer systems results in increased glass transition and decomposition temperatures, increased oxygen permeability and reduced flammability and heat evolution, as well as modified mechanical properties relative to conventional organic systems. © 1998 John Wiley & Sons, Ltd.
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  • 28
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 667-673 
    ISSN: 0268-2605
    Keywords: polysilanes ; poly(dimethylsiloxane) ; polyphosphazenes ; atom transfer radical polymerization ; controlled/‘living’ radical polymerization ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent advances in the synthesis of block, graft and star polymers containing inorganic macromolecular species are described. Anionic copolymerization techniques were used in the for-­mation of diblock copolymers of poly(styrene-block-methylphenylsilylene) and poly(isoprene-block-methylphenylsilylene) by the ring-opening polymerization of 1,2,3,4-tetramethyl-1,2,3,4-tetraphenylcyclotetrasilane initiated by living anionic polystyrene and isoprene respectively. Hydrosilation of an attachable initiator onto telechelic vinyl- or hydrosilyl-terminal or­-pendant poly(dimethylsiloxane) (PDMS) yielded a PDMS macroinitiator. This macroinitiator was used in atom transfer radical polymerization (ATRP) of styrene and isobornyl acrylate to produce ABA triblock copolymers. As a model for graft copolymers from a polyphosphazene backbone, chemical trans-­formation of hexachlorocyclotriphosphazene­resulted in hexafunctional molecules containing either benzyl bromide or bromopropionyl moieties. The initiator 1,1,3,3,5,5-hexakis[4-(2-bromopropionyloxymethyl)phenoxy]cyclotriphosphazene was used in the ATRP of styrene to yield a polymer with a narrow, monomodal molecular weight distribution. Chain extension of this star polymer with isobornyl acrylate is also described. © 1998 John Wiley & Sons, Ltd.
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  • 29
    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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  • 30
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 749-753 
    ISSN: 0268-2605
    Keywords: polymer ; silicon ; gel ; films ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of organic-inorganic polymer hybrids consisting of carbon-carbon and siloxane chains was investigated by radical polymerization of 3-methacryloxypropyltrimethoxysilane (MAS) followed by acid-catalyzed hydrolytic polycondensation. The condensation of poly(3-methacryloxypropyltrimethoxysilane) (S-PMA) of various molecular weights Mn =830-12000 prepared by polyaddition provided transparent and flexible free-standing hybrid gel films. The mechanical properties of these films were highly dependent on the carbon-carbon chain length: with an increase in the carbon-carbon chain length, the elasticity of gel films increased, while the tensile strength and Young's modulus decreased. Hydrolyzability of S-PMA decreased with an increase in the carbon-carbon chain length, resulting in the formation of rubber-like films with flexibility. © 1998 John Wiley & Sons, Ltd.
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  • 31
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    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 755-762 
    ISSN: 0268-2605
    Keywords: poly(vinyl alcohol) (PVA) ; sol-gel ; polymer hybrid ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Homogeneous poly(vinyl alcohol) (PVA)-silica gel polymer hybrids were prepared by in-situ hydrolysis of poly(vinyl acetate) (PVAc) in a sol-gel reaction mixture with tetramethoxysilane (TMOS). The degree of hydrolysis was evaluated by FTIR and 13C CP/MAS NMR; it increased with an increase in the acid catalyst and reached 85% with 1.6 ml of 0.1 M HCl. The homogeneity of the polymer hybrids obtained was maintained when the reaction was performed at 60 °C. However, the polymer hybrid became turbid with an increase of the amount of catalyst present when the reaction was conducted at room temperature. The homogeneity of the polymer hybrids obtained was evaluated by nitrogen sorption porosimetry of a porous silica that was obtained by charring the PVA hybrid. The results confirmed the molecular-level dispersion of the PVA in the hybrid. © 1998 John Wiley & Sons, Ltd.
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  • 32
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    Applied Organometallic Chemistry 12 (1998), S. 781-785 
    ISSN: 0268-2605
    Keywords: phosphonium ; polymer ; monomer ; film ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(arylene ether) main-chain phosphonium ionomers were successfully synthesized and characterized. The reaction scheme involved first preparing the poly(arylene ether phosphine oxide) by a nucleophilic step or condensation polymerization of bisphenolates on activated aryl halides, wherein phenyl phosphine oxide was the activating group. High-molecular-weight, tough, film-forming polymers were produced with glass transition temperatures of 200°C or higher. The resulting materials were successfully reduced using phenylsilane in refluxing chlorobenzene. The derived phosphine or phosphine/phosphine oxide copolymer was reacted with alkyl halides to produce the phosphonium salts. The resulting materials showed enhanced hydrophilicity and in some cases could be successfully dispersed in water. In addition, chromophores such as Methyl Orange and Methyl Red were combined with the backbone ionomer to produce new film-forming, ionically linked species. The materials are of general interest for situations where water-dispersible intermediates, e.g. coatings, fiber sizings etc. are required. The phosphonium salts can be converted back to the phosphine oxide in fairly high yields by simple thermal methods and in quantitative yield by chemical methods (e.g. the Wittig reaction). © 1998 John Wiley & Sons, Ltd.
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  • 33
    Electronic Resource
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    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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  • 34
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    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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  • 35
    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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  • 36
    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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  • 37
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    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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  • 38
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    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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  • 39
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    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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  • 40
    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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  • 41
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    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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  • 42
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    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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  • 43
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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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  • 44
    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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  • 45
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    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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  • 46
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    Applied Organometallic Chemistry 12 (1998), S. 87-97 
    ISSN: 0268-2605
    Keywords: antitumor ; metal complexes ; amine-carboxyborane ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The amine carboxyborane metal complexes, tetrakis - μ - (trimethylamine - boranecarbo - xylato)acetonitrile dicopper(II) and bis-μ- (morpholine-boranecarboxylato)zinc(II) dihydrate demonstrated cytotoxic activity against human Tmolt3, HeLa-S3 and MB-9812 cell growth.Tetrakis-μ-(trimethylamine-boranecarboxylato)-acetonitrile dicopper(II) and bis - μ - (morpholine - boranecarboxylato)zinc (II) dihydrate inhibited L1210 DNA, RNA and protein syntheses, with greatest inhibitory effects on DNA synthesis. The reduction in DNA synthesis correlates well with inhibition of de novopurine synthesis and the key enzymes involved in this pathway, i.e. IMP dehydrogenase and PRPP amido transferase. These compounds were also observed to induce DNA strand scission but did not appear to intercalate between base pairs of DNA, alkylate bases or cause cross-linking of the strands of DNA. Tetrakis-μ-(trimethylamine - boranecarboxylato)acetonitrile dicopper(II) also demonstrated the ability to inhibit L1210 DNA topoisomerase II activity. © 1998 John Wiley & Sons, Ltd.
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  • 47
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    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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  • 48
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    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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  • 49
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    Applied Organometallic Chemistry 12 (1998), S. 121-128 
    ISSN: 0268-2605
    Keywords: MMT ; soils ; interactions ; Fourier-transform IR ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and headspace analysis gas-phase infrared spectroscopy (HAGIS) were used to investigate interactions between soils and the gasoline additive methylcyclopentadienylmanganese tricarbonyl (MMT). Various soil samples, as well as alumina and silica substrates, were studied. Each substrate exhibited a splitting or broadening of the degenerate e ν(CO) band of MMT, suggesting an interaction involving one or two of the CO ligands. The adsorption was shown to be reversible under relatively mild conditions using HAGIS. The proposed interaction is of the Brønsted type, involving the carbonyl oxygen and a surface-bound water or hydroxyl group. This type of interaction could stabilize MMT by inhibiting photo-ejection of CO ligands, a common first step in the decomposition of organometallic carbonyl compounds such as MMT. © 1998 John Wiley & Sons, Ltd.
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  • 50
    ISSN: 0268-2605
    Keywords: trimethylantimony ; molecular rearrangement ; demethylation ; speciation ; hydride generation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The method of hydride generation for the speciation of antimony compounds was examined with respect to the problem of molecular "rearrangement'. Specifically, demethylation of trimethylstilbine during the analysis of trimethylantimony dichloride (Me3SbCl2) was studied. Previously published observations that enhanced demethylation takes place as a result of inadequate preconditioning of the analytical apparatus were found to be not reproducible. However, demethylation was enhanced as the pH decreased when using two different analytical methods: semi-continuous flow hydride generation-gas chromatography-atomic absorption spectrometry (HG- GC-AAS), and batch-type hydride generation- gas chromatography-inductively coupled plasma mass spectrometry (HG-GC-ICP MS). Applications of the hydride generation method to environmental samples revealed differences in analytical results at high and low pH, and enhanced demethylation taking place because of the matrix in a fungal extract sample. The authors recommend that researchers using the method of hydride generation for antimony compounds carefully test the reaction conditions with standard compounds and use the method of standard addition only. © 1998 John Wiley & Sons, Ltd.
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  • 51
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    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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  • 52
    ISSN: 0268-2605
    Keywords: arsenobetaine ; arsenocholine ; trimethylarsine oxide ; tetramethylarsonium iodide ; organic arsenic compound ; arsenite ; arsenate ; marine organisms ; cytotoxicity ; chromosomal aberration ; sister chromatid exchange (SCE) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arsenobetaine, arsenocholine, trimethylarsine oxide and tetramethylarsonium iodide, which are contained in marine fishery products, were examined for their potencies on cell growth inhibition, chromosomal aberration and sister chromatid exchange (SCE). Arseno- betaine, the major water-soluble organic arsenic compound in marine animals, exhibited very low cytotoxicity towards mammalian cells. This compound showed no cell growth inhibition at a concentration of 10 mg cm-3 and the cytotoxicity was lower than 1/14 000th of that of sodium arsenite and 1/1600th of that of sodium arsenate towards BALB/c 3T3 cells. The chromosomal aberrations caused by arsenobetaine at a concentration of 10 mg cm-3 consisted mainly of chromatid gaps and chromatid breaks, but in this concentration chromosomal breakage owing to its osmotic pressure is likely to be considerable. No SCE was observed at a concentration of 1 mg cm-3. Arsenocholine and trimethylarsine oxide also showed no cell growth inhibited at a concentration of 10 mg cm-3. However, tetramethylarsonium iodide inhibition the growth of BALB/c 3T3 at a concentration of 8 mg cm-3. These compounds exhibited a low ability to induce chromosomal aberrations at a concentration range of 2-10 mg cm-3 and no SCE was observed at a concentration of 1.0 mg cm-3. These results suggested that the major and minor organic arsenic compounds contained in marine fishery products are much less cytotoxic inorganic arsenic, methylarsonic acid and dimethylarsinic acid. © 1998 John Wiley & Sons, Ltd.
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  • 53
    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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  • 54
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    Applied Organometallic Chemistry 12 (1998), S. 155-160 
    ISSN: 0268-2605
    Keywords: tungsten trioxide ; electrochromism ; thin films ; chemical vapor deposition (CVD) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystalline and amorphous thin films of tungsten(VI) oxide can be prepared by chemical vapor deposition using a variety of volatile precursors below 500 °C. Deposition parameters for preparation of WO3 films from tungsten hexacarbonyl [W(CO)6], tungsten hexafluoride (WF6), tungsten ethoxides [W(OEt)x, x = 5, 6] and tetra(allyl)tungsten [W(η3-C3H5)4] are summarized. The electrochromic behavior of these films is comparable with that observed for WO3 films prepared by evaporation, sputtering and electrodeposition. © 1998 John Wiley & Sons, Ltd.
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  • 55
    ISSN: 0268-2605
    Keywords: chemical vapor deposition ; platinum ; palladium ; rhodium ; heterogeneous catalysts ; fluidized bed ; MOCVD ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new one-step method, entitled fluidized-bed metal-organic chemical vapor deposition (FBMOCVD) of preparing highly dispersed metal-supported catalysts is reported. The following complexes were studied and used as CVD precursors in presence of H2: [Rh(μ-Cl)(CO)2]2, Rh(allyl)3, Rh(acac)(CO)2, Pd(allyl)(hfac), Pd(allyl)(Cp), Pt(COD)(CH3)2. (acac, acetylacetonato; hfac, hexafluoroacetylacetonato; Cp, cyclopentadienyl; COD, cyclooctadienyl). In a first approach, depositions on planar substrates were carried out to establish the best experimental conditions to obtain good-quality deposits. X-ray diffraction, X-ray photo-electron spectroscopy and electron microprobe studies were realized on the resulting thin films. Analyses of the products contained in the gas phase after and during deposition were performed by mass spectrometry and GC-MS. Finally, catalysts prepared by FBMOCVD were characterized by transmission electron microscopy-energy dispersion spectroscopy (TEM-EDS), metal-loading determinations and specific-surface measurements (BET). Dispersed nanosized aggregates were obtained, showing high activities in alkene hydrogenation and alcohol hydrocarbonylation. © 1998 John Wiley & Sons, Ltd.
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  • 56
    ISSN: 0268-2605
    Keywords: Metal-organic chemical vapor deposition (MOCVD) ; precursors ; titanium ; vanadium ; carbonitride ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ceramic thin films containing titanium, vanadium, carbon, oxygen and nitrogen were obtained on steel substrates at 873 K, under nitrogen and helium gases and at low pressure, by chemical vapor deposition (CVD) from two organometallic precursors, CpTiCl2N(SiMe3)2 and Cp2VMe2 (Cp, cyclopentadienyl). Independent TG-DTA-MS and CVD studies of the two precursors showed their ability to co-decompose within compatible temperature and pressure domains. The mechanism of the reactions occurring inside the CVD apparatus was also approached by GC-MS and NMR analyses of the condensed decomposition products. CVD conducted under He gas confirmed that the formation of nitride resulted from the nitrogen atoms of the precursor, but the nitrogen content in the films remained lower than approx. 5%. Higher nitrogen contents (up to 12%) were only obtained when using ammonia as a carrier gas. Both precursors being air- and moisture-sensitive, high-purity CVD equipment was used to reduce oxycarbide formation. © 1998 John Wiley & Sons, Ltd.
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  • 57
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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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  • 58
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    Applied Organometallic Chemistry 12 (1998), S. 201-220 
    ISSN: 0268-2605
    Keywords: MOCVD ; molybdenum oxycarbide ; chromium oxycarbide ; coating ; kinetics ; microstructure ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A review of the coating kinetics of molybdenum and chromium oxycarbides and a study on the properties of deposited films are reported. Molybdenum carbonyl, chromium carbonyl and their mixture were used to prepare coatings at temperatures between 170 and 450 °C on SS304 or SiC substrates by a process of metal-organic chemical vapor deposition (MOCVD). The processing parameters of the coatings, such as the evaporation of precursors, coating pressure and temperature, are discussed along with the coating rates, compositions and other microstructural information, so to reveal the kinetics of the coating process on two different substrates. In addition, the chemical composition, crystalline phases and microstructure of the coatings obtained in various conditions are presented with the evidence interpreted by various electron-microscopic and spectroscopic techniques, including XRD, EDS, EPMA and XPS. The dependence of some properties, such as hardness, adhesive strength and corrosive resistance of the coatings on SS 304, on their composition and the deposited phases, i.e. as a function of coating temperature and pressure, is reviewed. © 1998 John Wiley & Sons, Ltd.
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  • 59
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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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    Applied Organometallic Chemistry 12 (1998), S. 293-293 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 61
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 62
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    Applied Organometallic Chemistry 12 (1998), S. 294-294 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 63
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 64
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    Applied Organometallic Chemistry 12 (1998), S. 295-296 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 65
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    Applied Organometallic Chemistry 12 (1998), S. 296-296 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 66
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 67
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    Applied Organometallic Chemistry 12 (1998), S. 296-297 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 68
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    Applied Organometallic Chemistry 12 (1998), S. 297-297 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 69
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 70
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    Applied Organometallic Chemistry 12 (1998), S. 298-298 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 71
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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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  • 72
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    Applied Organometallic Chemistry 12 (1998), S. 243-251 
    ISSN: 0268-2605
    Keywords: arsenic ; speciation ; algae ; Fucus gardneri ; arsenosugar ; high-performance liquid chromatography (HPLC) ; inductively coupled plasma-mass spectrometry (ICP-MS) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arsenic speciation in a brown alga, Fucus gardneri, collected in Vancouver, B.C., Canada, was carried out by using high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). Hydride generation-atomic absorption spectrometry (HG-AAS) was used for total arsenic determination. The relative amounts of some arsenosugars 1 in growing tips are found to be different in comparison with the remainder of the plant. Fucus samples collected in summer contain 9 ppm of total arsenic. Most of the arsenic species are extractable. Fucus samples collected in winter contain relatively higher amounts of arsenic, 16-22 ppm, but only low amounts of this are extractable. © 1998 John Wiley & Sons, Ltd.
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  • 73
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    Applied Organometallic Chemistry 12 (1998), S. 253-256 
    ISSN: 0268-2605
    Keywords: disilane ; gas source MBE ; synchrotron radiation ; silicon hydride ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Surface hydrogen and growth mechanisms are investigated for synchrotron radiation (SR)-assisted gas source molecular beam epitaxy (SR-GSMBE) using Si2H6 on the Si(100) surface in the low-temperature region. The surface silicon hydrides (deuterides) are monitored in situ during the epitaxial growth by means of infrared reflection absorption spectroscopy with a Si(100) substrate and a CoSi2 buried metal layer. It is concluded that the chemisorption of gas-phase reactive species such as SiHn and H generated by SR irradiation and the subsequent hydrogen desorption are the key mechanisms of SR-GSMBE at low substrate temperatures. © 1998 John Wiley & Sons, Ltd.
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  • 74
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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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  • 75
    ISSN: 0268-2605
    Keywords: carbohydrate surfactants ; wetting behaviour ; siloxane ; silane ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The wetting behaviour of carbohydrate surfactants bearing siloxane, carbosilane, polysilane or silane moieties has been investigated. By static surface tension (γlv, σ) and wetting tension (γsv-γsl, α) measurements on a non-polar perfluorinated surface (FEP®), the contact angles of aqueous surfactant solutions above the critical micelle formation concentration (cmc) were determined. Surface tension and wetting tension react independently on defined changes in the chemical structure of the surfactant molecules. Siloxane surfactants reduce the surface tension most effectively, whereas for a neopentyl-substituted silane derivative the lowest solid/liquid interfacial tension was found. The data for isomeric siloxanes, carbosilanes and silanes suggest that donor-acceptor forces at solid interfaces have a maximum range of about 4.5 Å. © 1998 John Wiley & Sons, Ltd.
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  • 76
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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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  • 77
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    Applied Organometallic Chemistry 12 (1998), S. 298-299 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 78
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    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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    Applied Organometallic Chemistry 12 (1998), S. 299-299 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 80
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    Applied Organometallic Chemistry 12 (1998), S. 299-301 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 81
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    Applied Organometallic Chemistry 12 (1998), S. 301-301 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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  • 82
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    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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  • 83
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    Keywords: α-Fe2O3 ; nanoparticles ; Morin transition ; antiferromagnetism ; weak ferromagnetism ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The magnetic properties of α-Fe2O3 nanoparticles of different shapes (spherical, rhombohedral and acicular), prepared as powders by a chemical route, have been investigated. The particle size effect on the Morin transition (TM = 263 K in the bulk system) have been studied by analyzing the temperature dependence of the zero-field-cooled (ZFC) and field-cooled (FC) magnetization. For spherical (average diameter between 10 and 50 nm) and rhombohedral (edge between 30 and 350 nm) particles, the Morin temperature was found to decrease with decreasing particle size and increasing magnetic field. On the other hand, acicular particles (major axis between 300 and 700 nm, minor axis between 70 and 100 nm) do not show the Morin transition, unless annealed. © 1998 John Wiley & Sons, Ltd.
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    Applied Organometallic Chemistry 12 (1998), S. 361-365 
    ISSN: 0268-2605
    Keywords: silicon nanoparticles ; optical properties ; CO2 laser ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silicon nanoparticles have been synthesized by heating reactant gases with a 500 W CO2 laser. A technique based on scattering of He-Ne laser light by particulates in a reaction flame has been developed for probing the particle size evolution during the process, in order to scale down the particle diameter (under 10 nm). The optical and structural properties of laser-synthesized silicon nanopowders obtained in different runs are reported. © 1998 John Wiley & Sons, Ltd.
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    Applied Organometallic Chemistry 12 (1998), S. 515-517 
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    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
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    New York, NY [u.a.] : Wiley-Blackwell
    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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  • 87
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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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  • 88
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    Applied Organometallic Chemistry 12 (1998), S. 523-529 
    ISSN: 0268-2605
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract
    Additional Material: 1 Ill.
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  • 89
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    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
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  • 90
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    Applied Organometallic Chemistry 12 (1998), S. 531-539 
    ISSN: 0268-2605
    Keywords: methylmercury ; estuarine sediment ; certification ; (BCR) ; quality control ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Legislation on methylmercury within the European Union (EU), e.g. in food (national regulations) or water (EC Directives), requires that the determinations are of proven quality; thus implies that they should be carried out under strict quality control (QC). One method of achieving good quality control in chemical analysis is to verify the analytical performance of methods by analysing Certified Reference Materials (CRMs). While CRMs of biological matrices (e.g. fish, mussels) are already available, there was a lack of materials for the QC of sediment analysis. This paper describes the preparation of an estuarine sediment reference material, the homogeneity and stability studies and the analytical work performed for the certification of the contents of total mercury and methylmercury. The results of a group of expert laboratories are discussed and the methods used to certify the mass fractions of total mercury (132 ± 3 mg kg-1 on a dry mass basis) and methylmercury (75.5 ± 3.7 μg kg-1 as CH3Hg+ on a dry mass basis) are described. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 2 Ill.
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  • 91
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    Applied Organometallic Chemistry 12 (1998), S. 643-650 
    ISSN: 0268-2605
    Keywords: tributyltin ; sediment ; degradation ; coastal British Columbia ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Butyltin concentrations in the sediments of two coastal areas of British Columbia, Canada, are reported. Two recent box cores from the deepest basin in the Strait of Georgia were sectioned and analyzed by GC-atomic emission spectrometry. No butyltin compounds were detected above 0.5 μgSn kg-1 (dry weight) in either core. These results are compared to those for a previous (1991) core from the same area. In that study, tributyltin (TBT) concentrations were in the range 1-2 μgSn kg-1 down the core and were higher than those of either of the degradation products, dibutyltin (DBT) and monobutyltin (MBT). Radioisotope dating (210Po-210Pb counting methods) was used to establish the rates of sedimentation of 0.25 and 2.6 cm y-1 at the two sites. Data suggest that a combination of rapid deposition of new, less-contaminated material and degradation of previously deposited butyltin compounds has resulted in the observed absence. Thirty-three surface sediments from the northern BC coastal harbor at Prince Rupert, collected in 1995, were analyzed for butyltin residues by GC-FPD. Concentrations of TBT, DBT and MBT were in the ranges from below the appropriate limit of detection (LOD) to 1262, to 109 and to 37 μgSn kg-1, respectively. TBT/DBT ratios ranged from 0.2 to 62 with most above unity, indicating that there is continuing fresh input of TBT. The sources are almost exclusively large ocean-going vessels that use the harbor for long-term anchorage. These findings are discussed with reference to the global TBT status. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
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  • 92
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    Applied Organometallic Chemistry 12 (1998), S. 577-584 
    ISSN: 0268-2605
    Keywords: organotin ; extraction ; analysis ; GC-FPD ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of: (1) the modifier type (methanol and formic, acetic and propionic acids), (2) complexing agents (diethylammonium diethyldithiocarbamate, ammonium pyrrolidinedithiocarbamate) either with or without acidic modifiers, (3) the extraction temperature (50-80 °C) and pressure (30-50 MPa), (4) the extraction procedure (static-dynamic or dynamic), and (5) the volume of static modifier, on the extraction efficiency of native butyl- and phenyl-tin compounds from sediment, were evaluated comprehensively. The highest extraction efficiency for butyl- and phenyl-tin compounds was obtained at 30 MPa and 50 °C by using CO2 modified with acetic acid (200 μl in the cell). Supercritical fluid extraction (SFE) extracts were hexylated and determined by GC-FPD using a 610 nm bandpass filter without any clean-up step. In summary, the developed analytical procedure is robust (no restrictor clogging; free from FPD interferences), it is low-cost (no complexing agents needed), it has a high sample throughput (〈3 h), it is independent of the matrix for the determination of butyltin compounds in sediment, and it provides the highest precision among the SFE procedures reported for organotin determination. © 1998 John Wiley & Sons, Ltd.
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  • 93
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    Applied Organometallic Chemistry 12 (1998), S. 585-590 
    ISSN: 0268-2605
    Keywords: butyltin ; estuarine microcosm ; environmental fate ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A radiotracer experiment was conducted in a controlled experimental ecosystem (microcosm) to determine the persistence and behavior of tributyltin (TBT) under conditions simulating a temperate, shallow estuarine ecosystem. Radiolabeled TBT was introduced to the estuarine microcosm, which contained estuarine water, sediment and fish. TBT and its degradation products were monitored for 40 days. TBT rapidly distributed among the compartments of the microcosm. The TBT half-life in the water column was 2.55 days for the first 11 days and then slowed to 13.4 days. More than 60% of the TBT and its metabolites were found in the sediment, indicating that the sediment was an important sink for butyltins. Higher concentrations of butyltins, relative to the water column concentrations, were found in the surface microlayer. TBT could be bioconcentrated by the fish to levels more than 200 times the exposure concentration, and underwent rapid degradation in the fish body, so that high concentrations of its metabolites were found in the fish. The concentrations of TBT adsorbed on the suspended particles were three orders of magnitude greater than that in dissolved form. © 1998 John Wiley & Sons, Ltd.
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  • 94
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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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  • 95
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    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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  • 96
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    Applied Organometallic Chemistry 12 (1998), S. 651-656 
    ISSN: 0268-2605
    Keywords: butyltin ; TBT ; DBT ; MBT ; beluga whales ; St Lawrence River estuary ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fifty-two beluga whale samples (Six liver samples, and 46 blubber samples including ones from different depths of the fat layer) from the St Lawrence River, Canada, were analyzed for butyltin compounds (mono-, di-, and tri-butyltin) with a view to investigating the occurrence and contamination of butyltin in these animals. A special procedure was also developed for the determination of butyltin compounds in blubber samples with high lipid content (up to 95%). Total-butyltin concentrations in liver samples were found to be much higher than those in the blubber samples. The concentrations of butyltin compounds in blubber samples were observed to be related to their lipid content. Concentration levels of butyltin species in beluga whale were compared with those in other marine vertebrates in other parts of the world. The presence of butyltin compounds in liver and blubber samples suggests the accumulation of these toxicants by beluga whale. © 1998 John Wiley & Sons, Ltd.
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  • 97
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    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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  • 98
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    Applied Organometallic Chemistry 12 (1998), S. 763-770 
    ISSN: 0268-2605
    Keywords: siloxane network ; contact angle ; sol-gel reaction ; polydimethylsiloxane ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polydimethylsiloxane (PDMS) hybrid networks have been prepared by the reaction of PDMS(OH)2, average molecular weight 26 × 103, 43.6 × 103 and 58 × 103, and methyltriethoxysilane (MeTEOS, 10-60 wt%) using a dibutyltin dilaurate or dibutyltin diacetate catalyst. By hydrolysis and homo- and co-condensation, MeTEOS forms a siliceous domain (MeSD) and acts as a crosslinker for the PDMS domain. Kinetic studies showed that high MeTEOS and catalyst concentrations and reduction of free surface area favor fast gelation and efficiency in converting MeTEOS to the MeSD. Under the water-sparse conditions utilized, cure was slow and substantial evaporative loss of MeTEOS occurred. © 1998 John Wiley & Sons, Ltd.
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  • 99
    ISSN: 0268-2605
    Keywords: organophosphazenes ; liquid crystals ; phase transition ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organophosphazenes with a similar mesogenic moiety were prepared and their mesogenicity was studied by differential scanning calorinetry (DSC) measurements and polarizing microsope observations. In cyclotriphosphazenes with alk-­oxybiphenyl and Schiff base moieties, mesomorphic phase transitions were observed, but no mesomorphic phase was observed for the corresponding cyclotetraphosphazenes. In polyphos-­phazenes with an alkoxybiphenyl moiety, no mesomorphic phase was observed. The molecular structure of cyclotriphosphazenes facilitated the formation of a mesomorphic layer structure; in contrast, the formation of a mesomorphic layer structure did not occur in cyclotetraphosphazenes and polyphosphazenes, even though they bore a similar mesogenic moiety. Moreover, in cyclotriphosphazenes with an optically active alkoxybiphenyl group, a smectic C* phase was observed. The spontaneous polarization of the compound was -190 μ C m-2 at 436 K in 25 μ in cell using the triangular-wave method. © 1998 John Wiley & Sons, Ltd.
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  • 100
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    Applied Organometallic Chemistry 12 (1998), S. 657-657 
    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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