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  • 1
    Electronic Resource
    Electronic Resource
    Spectra and structure of small ring compounds. XLVIII. Conformational stability of methylcyclobutane from low frequency Raman data of the gas (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 545-551 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The low frequency (500–80 cm−1) Raman spectra of gaseous methylcyclobutane, c-C4H7CH3, and methyl-d3-cyclobutane have been recorded. A series of Q branches beginning at 161 cm−1 for the light molecule and 154 cm−1 for the d3 compound with successive transitions falling to lower frequencies have been assigned to the ring puckering vibrations of both the low energy equatorial and high energy axial conformers. These data have been fitted to an asymmetric potential function of the form: V(cm−1)=(4.78±0.10)×105X4−(3.08±0.04)×104X2 +(2.18±0.1)×104X3 with an assumed reduced mass of 160 amu for the light compound. Utilizing this potential the difference between the puckering angles for the two conformers was calculated to be 4.3° with the equatorial conformer having the larger value of 20.7°. A similar potential was obtained for the d3 molecule. The energy difference between the equatorial and axial forms was found to be 247±20 cm−1 (706 cal/mol) and a barrier of 641±20 cm−1 (1.83 kcal/mol) was found for the interconversion. Experimental values for the ΔH of both the liquid (354±179 cm−1) and gas (295±75 cm−1) from relative intensities of different Raman band pairs over 85 and 37 °C temperature ranges, respectively, were found to be consistent with the value obtained from the potential function. These results are compared to the corresponding quantities for similar molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452305
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  • 2
    Electronic Resource
    Electronic Resource
    Spectral characteristics of plasma emission during ArF excimer laser ablation of YBa2Cu3O7 (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 469-471 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In order to characterize the laser ablation process as it relates to the deposition of high Tc superconducting thin films, optical emission spectra produced during ArF excimer laser ablation of the high Tc superconductor YBa2Cu3O7 were studied. The population of excited states within the gas phase blow-off material depends strongly on excimer laser fluence at 193 nm. Ablation using relatively low excimer laser fluences produces a significant fraction of YO in the gas phase. The plasmas derived from ablation of targets made from the high Tc material are similar to plasmas observed from ablation of the individual components BaCO3, CuO, and Y2O3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101555
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  • 3
    Electronic Resource
    Electronic Resource
    The gypsy retrotransposon of Drosophila melanogaster: Mechanisms of mutagenesis and interaction with the suppressor of Hairy-wing locus (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 239-248 
    Details
    ISSN: 0192-253X
    Keywords: Transposable element ; Transcription factor ; Suppression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have used the yellow gene of Drosophila melanogaster as a model system in which to study the molecular mechanisms by which the gypsy retrotransposon causes mutant phenotypes that can be reversed by nonalleiic mutations at the suppressor of Hairy-wing locus. This gene encodes a 109,000 dalton protein that contains an acidic domain and 12 copies of the Zn finger motif, which are characteristic of some transcription factors and DNA binding proteins. The suppressible y2 allele is caused by the insertion of the gypsy element at -700 bp from the start of transcription of the Yellow gene, resulting in a phenotype characterized by mouth parts and denticle belts in the larvae, and by bristles in the adults, that show wildtype coloration, but mutant wings and body cuticle in the adult flies. This phenotype is the result of the interaction of gypsy sequences homologous to mammalian enhancers with tissue-specific yellow transcriptional regulatory elements located upstream from the gypsy insertion site and responsible for the expression of the yellow gene in the mutated tissues. This interaction is dependent on the binding of the su(Hw) protein to the specific gypsy sequences involved in the induction of the mutant phenotype.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100313
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of trimellitic anhydride in workplace air using reverse phase high performance liquid chromatography (1986)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 308-309 
    Details
    ISSN: 0935-6304
    Keywords: High performance liquid chromatography, HPLC ; Reverse phase ; Internal standard ; Trimellitic anhydride ; Air sample ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240090516
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  • 5
    Electronic Resource
    Electronic Resource
    Cellular dynamics of conjugation in the ciliate euplotes aediculatus. I. Cytoskeletal elements (1987)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 192 (1987), S. 27-42 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fate and possible roles of the cytoskeleton in the process of conjugation in the hyptrich ciliate Euplotes aediculatus were investigated. Following the coalescence of the plasma membranes of the conjugant cells, a fusion zone or bridge of cytoplasm contributed by both partners is constructed. The sub-alveolar microtubule layers of the vegetative cell cortex remain in place to define the fusion zone boundaries after cell union. The initial fusion zone consists primarily of featureless ground cytoplasm; soon the ground plasm becomes crowded with microtubules and anastomosing smooth endoplasmic reticulum, which become displaced only late in conjugation as the migratory pronuclei are exchanged between partners. Fusion zone microtubules, functioning in some undetermined way, may be involved in the nuclear migration. Resorption of the posterior portion of each partner's buccal apparatus results in the degradation of the component cilia within acid phosphatase-positive autophagic bodies. Silver staining for light microscopy shows that the late fusion zone contracts forward from the posterior border, then constricts to separate the conjugants. In some separating pairs remnants of a microfilamentous assembly are seen at the posterior edge of the fusion zone; the full extent of this system may be masked by partial degradation due to osmium tetroxide fixation. Treatment of conjugants for 6 hours with cytochalasin B prevents separation, possibly through inhibition of the actin-like microfilament assembly in the fusion zone. The observations and experiments favor a model of cell separation following conjugation in which the fusion zone is resorbed by motile or contractile processes occurring within or around the fusion bridge itself.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051920104
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  • 6
    Electronic Resource
    Electronic Resource
    Cellular dynamics of conjugation in the ciliate euplotes aediculatus. II. Cellular membranes (1987)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 192 (1987), S. 43-61 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The formation and subsequent dissolution of a common bridge of cytoplasm between conjugating ciliated protozoan cells provides an excellent opportunity to follow the dynamics of the cellular membrane systems involved in this process. In particular, separation of conjugant partners offers the chance to observe, at a fixed site on the cell surface, how the ciliate surface complex of plasma and alveolar membranes (collectively termed the “pellicle”) is constructed. Consequently, cortical and cellular membranes of Euplotes aediculatus were studied by light and electron microscopy through the conjugation sequence. A conjugant fusion zone of shared cytoplasm elaborates between the partner cells within their respective oral fields (peristomes) to include microtubules, cytosol, and a concentrated endoplasmic reticulum (heavily stained by osmium impregnation techniques) that may also be continuous with cortical ER of each cell. Cortical membranes displacd by fusion are autolyzed in acid phosphatase-positive lysosomes in the fusion zone. As conjugants separate, expansion of the plasma membrane may occur through the fusion of vesicles with the plasma membrane, presumably at bare membrane, presumably at bare membrane patches near the fusion zone. The underlying cortical alveolar membranes and their plate-like contents are reconstructed beneath the plasma membrane, apparently by multiple fusions of dense-cored alveolar precursor vesicles (APVs). These precursor vesicles themselves appear to condense directly from the smooth ER present in the fusion zone. No Golgi apparatus was visible in the fusion zone cytoplasm, and no step of APV maturation that might involve the Golgi complex was noted.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051920105
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  • 7
    Electronic Resource
    Electronic Resource
    Platelet-derived growth factor stimulates rapid polyphosphoinositide breakdown in fetal human fibroblasts (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 124 (1985), S. 391-396 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The addition of human platelet-derived growth factor (PDGF) to confluent, quiescent cultures of human diploid fibroblasts induced the rapid breakdown of cellular polyphosphoinositides. The levels of 32P-labeled phosphatidylinositol 4,5-bisphosphate (PIP2), phosphatidylinositol 4-phosphate (PIP), and phosphatidylinositol (PI) decreased by 30 to 40% within 1 min after exposure of the cells to PDGF. The levels of PIP and PIP2 returned to their initial values within 3 and 10 min, respectively, after PDGF addition. The level of PI continued to increase after it had returned to control values and was up threefold within 30 min after PDGF addition. In cells prelabeled with myo-[3H]inositol PDGF caused an eightfold increase in the levels of inositol trisphosphate (IP3) within 2 min. Lesser increases, twofold and 1.3-fold, respectively, were seen in levels of inositol bisphosphate (IP2) and inositol monophosphate (IP). Within 10 min after PDGF addition the levels of all three inositol phosphates had decreased to control values. The levels of IP3 measured 2 min after PDGF addition depended on the PDGF concentration and were maximal at 5-10 ng/ml of PDGF. Similar concentrations of PDGF stimulate maximal cell growth and DNA synthesis in these cells.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041240306
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetische Racematspaltungen ausgehend von rac-Alkoholen oder rac-Carbonsäurehalogeniden unter Mitwirkung optisch aktiver Induktorbasen (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 533-538 
    Details
    ISSN: 0170-2041
    Keywords: Resolution, kinetic ; Chiral tertiary amines ; Chiral esters ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetic Resolutions Starting with rac-Alcohols or rac-Acyl Halides Using Optically Active Inductor BasesIn the reaction of one mole equivalent of achiral acyl halides with two equivalents of rac-alcohols in the presence of one equivalent of an optically active inductor base (tertiary amine) partially optically active esters and partially optically active alcohols are formed, having in some cases high optical purity (60 - 70%). The alcohol moiety of the ester and the unchanged alcohol are of opposite configuration. Treatment of two equivalents of rac-acylhalides with one equivalent of an achiral alcohol and an inductor base also leads to a high degree of optical induction. The carbonic acid moiety in the ester and the unchanged acid are of opposite configuration. The optical induction is influenced a) by the ligands linked to the reaction centers, b) by the relative quantities of the reacting partners, c) by the solvent, and d) by the temperature.
    Notes: Bei der Umsetzung eines Moläquivalents achiraler Carbonsäurehalogenide mit zwei Moläquivalenten rac-Alkoholen entstehen unter Mitwirkung von einem Moläquivalent einer optisch aktiven Induktorbase (tertiäres Amin) partiell optisch aktive Ester sowie partiell optisch aktive Alkohole in zum Teil hoher optischer Reinheit (60 - 70%). Der im Ester gebundene Anteil an Alkohol sowie der nicht umgesetzte Alkohol haben entgegengesetzte Konfiguration. Der Induktionsgrad ist ähnlich hoch, wenn man zwei Moläquivalente eines rac-Carbonsäurehalogenids mit je einem Moläquivalent eines achiralen Alkohols und einer Induktorbase umsetzt. Der Carbonsäureanteil im Ester und die freie Säure haben entgegengesetzte Konfiguration. Die optischen Induktionen werden beeinflußt a) durch die Art der mit den Reaktionszentren verknüpften Liganden, b) durch die relativen Mengen der Reaktionspartner, c) durch das Lösungsmittel und d) durch die Temperatur.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890194
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  • 9
    Electronic Resource
    Electronic Resource
    Spectra and structure of small ring compounds. XLIXFor Part XLVIII, see J. Chem. Phys. 86, 545 (1987). - Raman and infrared spectra, conformational analysis and vibrational assignment of methylcyclobutane and methyl-d3-cyclobutane (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 18 (1987), S. 581-592 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman (3500-20 cm-1) and infrared (3500-50 cm-1) spectra of gaseous and solid methylcyclobutane and methyl-d3-cyclobutane have been recorded. Additionally, the Raman spectra of the pure liquids have been recorded and qualitative depolarization values have been obtained. The spectra have been interpreted on the basis that both the axial and equatorial conformers are present in the fluid phases and that the equatorial form is thermodynamically preferred and the only form present in the annealed solid. All 39 of the normal vibrational modes have been assigned for both the d0 and d3 compounds. An abundance of spectral evidence is presented which indicates extensive coupling between the vibrations associated with the ring and those of the methyl group. The CH3 internal torsional mode has been observed in the Raman spectrum of the solid at 232 cm-1 and utilizing this frequency the periodic threefold barrier to internal rotation has been calculated to be 1190 cm-1 (3.40 kcal mol-1). The fundamental ring puckering mode has been assigned from the Raman spectra of the gases to weak features observed at 161 and 154 cm-1 for the d0 and d3 compounds, respectively. All of these results are compared with the corresponding quantities for some similar molecules.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250180809
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