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  • Wiley-Blackwell  (349)
  • Springer Science + Business Media  (182)
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  • 1
    ISSN: 1434-1948
    Keywords: Imidazaboles ; Carbene-borane adducts ; Azole-borane adducts ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation and characterization of five new imidazabole derivatives is reported: 1,5-dibenzyl-4,4,8,8-tetrahydroimidazabole (2), 4,4,8,8-tetrafluoro-1,5-dimethylimidazabole (3), 4,4-difluoro-8,8-dihydro-1,5-dimethylimidazabole (4), 4,4,8,8-tetrachloro-1,5-dimethylimidazabole (5), and 4,4,8,8-tetraethyl-1,5-dimethylimidazabole (6). The structures of compounds 2-6 as dimeric carbene-borane adducts rather than dimeric N-borane adducts are discussed on the basis of NMR (2-6) and X-ray diffraction data (2, 3, 5 and 6).
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  • 2
    Publication Date: 2014-04-01
    Description: PurposeWhen dealing with remediation projects in zones affected by mining activities, the risk posed by the ingestion of the plants by fauna is often forgotten. The purpose of this study is the assessment of arsenic assimilation by the natural vegetation in these areas. To study the transfer to the trophic chain two mammals, the sheep and the vole are selected. The risk analysis is founded on the contribution of these natural plants to the ingestion.Material and methodsSoil samples and the same number of plants (165) growing in the soils were collected in an old mining area in the southeast of Spain. Physico-chemical properties were calculated by means of the usual procedures. To determine the arsenic content, the soil samples and plant materials were digested by means of a microwave system and the arsenic concentration was determined using atomic fluorescence spectrometry with automated continuous flow hydride generation (HG-AFS). A semiquantitative estimation of the mineralogical composition of the samples was made by X-ray diffraction analysis.Results and discussionThe mineralogy and As content of the soils studied depends on the materials related with the mining activity. The descriptive statistical analysis of the population of plants studied points to an As range of 0.31–150 mg/kg in roots, although the concentration in shoots was lower (0.21–83.4 mg/kg). Bioconcentration (BCF) and transfer factors (TF) were studied for each plant species and soil type on which it grew. The results show that As transfer depends on the plant species and the characteristics of the soil. The potential risk of As entering the food chain through the plant species was evaluated. The exposure pathway considered was oral ingestion, calculating the contribution of the plant to the daily dose based on the arsenic concentration in the shoots of the plants analysed.ConclusionsIn the samples studied, the levels of As in roots were higher than in shoots, and increased with the As concentration in the soil. The BCFs were generally very low, and the TFs while slightly higher, seldom exceeded unity. When undertaking with the phytoremediation of contaminated sites, the contribution of the As level in plants to the daily diet of animals should be used as an indicator for the screening of the vegetal species to be used. ©2014 Springer-Verlag Berlin Heidelberg
    Print ISSN: 1439-0108
    Electronic ISSN: 1614-7480
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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  • 3
    ISSN: 0935-6304
    Keywords: High resolution GC-MS ; Mass spectrometry ; Anise oil ; Catalytic transformation ; Zeolite Y ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 4
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The main fragmentation pathway of vinyl triflates in mass spectra involves the loss of CF3SO2·, followed by the loss of olefin and/or CO. The loss of TfOH takes place with fragmentation of a vinylic C—H bond. TfOH2+ ions are formed via regiospecific double hydrogen transfer from five- and six-membered cyclic triflates.
    Additional Material: 3 Tab.
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  • 5
    ISSN: 0749-1581
    Keywords: 1H, 13C, 15N and 113Cd NMR ; Two-dimensional NMR ; CP/MAS NMR ; Hg and Cd complexes 4(1H) -Quinazolinone-2,3-dihydro-2-thioxo ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Cd(II) and Hg(II) complexes of 4(1H)-quinazolinone-2,3-dihydro-2-thioxo (1) and the free ligand were studied by 1D and 2D multinuclear magnetic resonance in solution and 13C cross polarization magic angle spinning NMR in the solid state. Compound 1 adopts only one of five possible tautomeric structures in solution, namely the thiouracyl-like structure. It was found that the metal atom is linked to two molecules of deprotonated 1 by N-1 and coordinated by the sulphur atom. The compounds retain the same structure in the solid state and in dimethyl sulphoxide solution.
    Additional Material: 2 Ill.
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  • 6
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have prepared two new tetracyclic phenylboronic esters 4 and 5 derived from myo-inositol and from 1,2-O-isopropylidene-myo-inositol, respectively. The structures of these compounds were established from NMR and IR spectra, elemental analyses, and an X-ray diffraction study in the case of 4. Compound 4 is a tetracyclic derivative of the less stable conformer of inositol (five axial hydroxy groups and one equatorial) with two dioxaboroline rings at opposite faces of the six-membered ring, one formed between the boron atom and the axial hydroxyl groups at C-3 and C-5 and the other between the boron atom and the hydroxyl groups at C-4 and C-6, and a dioxaborolidine ring bridging C-1 and C-2 at axial and equatorial positions. A similar structure was found for 5 with the difference that bridging C-1 and C-2 there is a dioxolane ring. The boron atoms are planar with their attached atoms, stabilized by retrocoordination between the boron and oxygen and carbon atoms, respectively. The two phenyl rings that are in the same face of the molecule are essentially parallel, with a dihedral angle between planes of 28.26 ± 0.79°.
    Additional Material: 2 Ill.
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  • 7
    ISSN: 1434-1948
    Keywords: Alkaline earth metals ; Group-13 metals ; Coordination chemistry ; Bis(3,5-di-tert-butyl-1-hydroxy-2-phenyl)amine ligand ; Nonacoordinated strontium compound ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of 3,5-di-tert-butylcatechol and aqueous ammonia with boron, aluminum, gallium, or strontium chloride, or with calcium or barium acetate produce, under oxidizing conditions, neutral complexes of stoichiometric formulae ML (M = BCl), ML2, [M = Al (2), Ga (3), Ca (4), and Ba (5)], and ML3H [M = Sr (6)] [L = different oxidation states of bis(3,5-di-tert-butyl-1-hydroxy-2-phenyl)amine]. The structures of 1 and 4-6 were established by 1H- and 13C-NMR spectroscopy and of 2, 3, and 6 by X-ray diffraction. The coordination compound ClBL (1) was obtained by transmetallation of ZnL2 with BCl3. It is a tetracyclic compound with tetracoordinated boron and nitrogen atoms, the ligand being in the reduced form, bis(hydroxyphenyl)amine. The paramagnetic complexes 2 and 3 crystallized in the triclinic system and are hexacoordinated with two orthogonal planar ligands bonded to the metal atoms. The ligands appear in two different oxidation states: one as the monoanion and another as a radical dianion. Based on their X-ray diffraction molecular structures, it is deduced that both ligands have similar structures, confirming electronic delocalization and fast interconversion of their oxidation states. Ca and Ba complexes are diamagnetic and hexacoordinated, both ligands being monoanions The strontium complex crystallized in the monoclinic system, the metal atom is nonacoordinated, having two ligands as monoanions, and a third one is a neutral protonated diquinone. Its structure is a distorted helix with three paddles in a C3 geometry and its unexpected diamagnetic behaviour is due to the presence of a reduced protonated ligand.
    Additional Material: 4 Ill.
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  • 8
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The copolymerization of β-pinene with styrene oxide (SO) and β-pinene with N-vinylpyrrolidone (VP) was investigated by using SnCl4 in dichloromethane diluent at low temperature. Monomer reactivity ratios were evaluated for both copolymers at -80°C; these are r1(SO) = 2.979 and r2(β-pinene) = 0.002 and r1(VP) = 0.096 and r2(β-pinene) = 0.294.
    Additional Material: 1 Ill.
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  • 9
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of intracellular pH (pHin) in the regulation of cell growth in both normal and transformed cells is a topic of considerable controversy. In an effort to study this relationship NIH 3T3 cells were stably transfected with the gene for the yeast H+-ATPase, constitutively elevating their pHin. The resulting cell line, RN1a, has a transformed phenotype: The cells are serum independent for growth, clone in soft agar, and form tumors in nude mice. In the present study, we further characterize this system in order to understand how transfection with this proton pump leads to serum-independent growth, using defined media to investigate the effects of specific growth factors on the transfected and parental NIH 3T3 cells. While both cell lines show similar growth increases in response to platelet-derived growth factor (PDGF)-BB and epidermal growth factor (EGF), they respond differently to insulin, insulin-like growth factor-I (IGF-I) and PDGF-AA. RN1a cells exhibit increased growth at nanomolar concentrations of insulin but the parental cells had only a relatively minor response to insulin at 10 μM. Both cell lines showed some response to IGF-I in the nanomolar range but the response of RN1a cells was much larger. Differences in insulin and IGF-I receptor number alone could not explain these results. The two cell lines also respond differently to PDGF-AA. RN1a cells are relatively insensitive to stimulation by PDGF-AA and express fewer PDGF α receptors as shown by Northern blots and receptor-binding studies. We propose a unifying hypothesis in which the H+-ATPase activates a downstream element in the PDGF-AA signal transduction pathway that complements insulin and IGF-I signals, while leading to downregulation of the PDGF α receptor. © 1994 wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 10
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: NIH-3T3 cells transfected with yeast H+-ATPases (RN1A cells) are tumorigenic (Perona and Serrano, 1988, Nature, 334: 438). We have previously shown that RN1a cells maintain a chronically high intracellular pH (pHin) under physiological conditions. We have alsoshown that RN1a cells are serum-independent for growth, maintain a higher intracellular Ca2+(in), and glycolyze more rapidly than their non-transformed counterparts (Gillies et al., Proc. Natl. Acad. Sci., 1990, 87: 7414; Gillies et al., Cell. Physiol. Biochem., 1992, 2: 159). The present study was aimed to understand the interrelationships between glycolysis, pHin, and [Ca2+]in in RN1a cells and their non-transformed counterparts, NIH-3T3 cells. Our data show that the higher rate of glycolysis observed in RN1a cell is due to the presence of low affinity glucose transporters. Consequently, the higher rate of glycolysis is exacerbated at high glucose concentration in RN1a cells. Moreover, the maximal velocity (Vmax) for glucose utilization is up to sixfold higher in RN1a cells than in the NIH-3T3 cells, suggesting that the number of glucose transporters is higher in RN1a than NIH-3T3 cells. Glucose addition to NIH-3T3 cells results in modest decreases in both pHin and [Ca2+]in. In contrast, RN1a cells respond to glucose with a large decrease in pHin, followed by a large decrease in [Ca2+]in. The decrease in [Ca2+]in observed upon glucose addition is likely due to activation of Ca2+-ATPase by glycolysis, since the Ca2+ decrease is abolished by the Ca2+ ATPase inhibitors thapsigargin and cyclopiazonic acid. Glucose addition to ATP-depleted cells results in a decrease in [Ca2+]in, suggesting that ATP furnished by glycolysis is utilized by this pump. © 1994 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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