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  • Analytical Chemistry and Spectroscopy  (2,665)
  • Life and Medical Sciences  (1,981)
  • FLUID MECHANICS AND HEAT TRANSFER
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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of 252californium plasma desorption and fast atom bombardment mass spectrometry for analysis of small peptides (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 380-387 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The data obtained with 252Cf plasma desorption (PD) and fast atom bombardment mass spectrometry of eight tri-, tetra- and pentapeptides were compared. Good spectra were obtained with 1-10 nmol of peptide. In both techniques molecular weight information was obtained. The PD mass spectra are often dominated by the cationized molecular ions in contrast to the fast atom bombardment (FAB) mass spectra, where cationization is rarely observed. Amino acid content is reflected in the immonium ions equally well in both techniques. The fragmentation patterns observed with the two techniques are almost identical. However, practical sequencing of peptides based on either FAB or PD mass spectrometry of underivatized peptides alone is difficult. This is due to the unpredictable and sometimes absent cleavage yield at certain peptide bonds. Another difficulty is the many simultaneous fragmentation pathways. However, for many peptides enough information is present to allow sequence determination for at least a major part of the molecule.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200120805
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  • 2
    Electronic Resource
    Electronic Resource
    Total reflection x-ray fluorescence spectrometry of metal samples using synchrotron radiation at SSRLPresented at the European Conference on EDXRS. Myconos, Greece, 30 May-6 June 1992. (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 22 (1993), S. 277-280 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: It was demonstrated that a total reflection x-ray fluorescence spectrometer, using monoenergetic synchrotron radiation as the primary x-ray source, is suitable to measure the concentration of transmutational elements in Cu and Fe metal matrices. In a typical irradiation of copper with 590 MeV protons or with spallation neutrons, where the damage dose is 0.4 dpa (displacement per atom), the calculated concentration of transmutational elements is Ni 25, Co 8 and Fe 8 μg g-1. The results show that the minimum detectable concentrations were lower than these values. The energy of the sychrotron radiation was set just below the K-edge energy of the matrix element, eliminating the large peak due to the matrix. As an example, in the case of a Cu (Z = 29) matrix, the minimum detectable concentration for Ni (Z = 28) was as low as 3 μg g-1. In order to check systematically the possible geometric arrangements of beam direction-reflector position-detector position, a new vacuum chamber was designed and tested. It provides all technical components for remote control of the adjustment procedure to align the reflector in total reflection geometry. Two ways of positioning the reflector in the beam, vertical to the plane of polarization and parallel to that plane, were investigated, to find the best excitation conditions and lowest limits of detection. A few pg corresponding to a concentration of ng g-1 of samples where the matrix can be easily removed as in aqueous or acidic solutions and 50 ng g-1 concentration of metals in a light matrix as in oil were found as detection limits.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300220419
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation of biological tissue sections for correlative ion, electron, and light microscopy (1984)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 1 (1984), S. 299-309 
    Details
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Ion microscopy ; Correlative microscopy ; Electron probe microanalysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In order to correctly interpret the chemical images obtained using ion microscopy (IM), it is useful to correlate them with the information provided by conventional light microscopy (LM), secondary electron imaging (SEI), backscattered electron imaging (BEI), and electron probe microanalysis (EPMA). Accordingly, we have devised a technique of specimen preparation which allows for the application of several different microanalytical techniques to a single histologic section mounted on the same substrate. Sections are cut onto polyester plastic coverslips (devoid of peaks for any element with atomic number 〉 9 using EPMA) and studied by LM. After a light rotary coating with carbon (to prevent charging), the section can then be examined by SEI, BEI, and EPMA. Specific areas can be marked for IM study either with an objective-mounted pin tissue microlocater, or by placing small pieces of metal foil, cut in specific geometric shapes, over features of interest. After sputter-coating the sample with platinum, metal-free shadows are visible using a low-power reflected light microscope available on a typical IM sample chamber as a guide for ion beam placement. The conductive coatings also minimize specimen charging during IM. Post-IM light microscopy, SEI, and BEI are used to confirm the location of specific areas probed in the IM experiments and to provide information on differential ion-sputtering artifacts and tissue contaminants. This new correlative technique should permit better understanding of the images obtained with these diverse instruments.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060010309
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  • 4
    Electronic Resource
    Electronic Resource
    Reproducibility of sample separation using liquid or forced air convection thermostatted high performance capillary electrophoresis systems (1992)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 517-525 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Run-to-run reproducibility ; Capillary thermostatting ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Run-to-run sample separation reproducibility has been compared on two commercial high performance capillary electrophoresis units which differ in the mode by which the capillary temperature is thermostatted. Three standard analytes, differing dramatically in molecular character and size, were used for the analysis: benzoic acid, a 14 amino acid peptide from human chorionic gonadotropin, and ribonuclease A represent, respectively, small stable organic molecules, small peptides with little or no secondary structure, and proteins with secondary structure. These standards were evaluated with regard to reproducibility of migration time, peak area, and peak height. The analyses, performed in buffers of optimum pH for the separations, demonstrated that the liquid and forced air convection thermostatted systems both performed extremely well. The reproducibility, as judged by the percent coefficient of variance (% CV) of replicate analyses, was generally found to be less than 1 % (migration time); the reproducibility decreased in the order migration time 〉 peak height 〉 peak area. Whereas the absolute % CV values for MTrel (migration relative to a standard) observed with the liquid thermostatted system were 2- to 4-fold lower than those observed with the forced air convection thermostatted system, there was little statistically significant difference between the two. As expected, the data indicated a reduction in reproducibility as the complexity of the analyte increased, perhaps as the result of an increased potential for wall interactions. Comparing separations in which low (≍1 watt/meter [W/m] of capillary) and high (〉5 W/m) Joule heat was generated by altering the sodium chloride content of the buffer revealed few statistically significant differences in the reproducibility obtained from the two systems. With these particular standard analytes and their respective buffer systems, there appears to be little difference between forced air convection and liquid thermostatting of the capillary.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240150807
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  • 5
    Electronic Resource
    Electronic Resource
    Modulatory function of protein kinase C in the activation of ornithine decarboxylase and in cAMP production in rat osteoblasts (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 138 (1989), S. 548-554 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of activation of protein kinase C on stimulation of ornithine decar-boxylase (ODC) activity and cAMP production was studied in fetal rat osteoblasts. Both phorbol 12-myristate, 13-acetate (PMA), an activator of protein kinase C, and 4α-phorbol, ineffective in activating protein kinase C, failed to stimulate ODC activity and cAMP production. We tested the effect of protein kinase C on stimulation of ODC activity by parathyroid hormone (PTH) and forskolin. In contrast to PTH-stimulated ODC activity, which was not affected by PMA, forskolin-stimulated (1 and 10 μM) ODC activity was dose dependently reduced. PMA (400 nM) reduced both 1 and 10 μM forskolin-stimulated ODC activity to the same level, ∼ 3 nmol CO2/mg protein, which suggests a controlling role of protein kinase C in forskolin-stimulated ODC activity. The study of the effect of protein kinase C on PTH- and forskolin-stimulated cAMP production also revealed differences between PTH and forskolin. When PMA was added simultaneously with PTH (4 and 20 nM) or forskolin (1 and 10 μM) the PTH-stimulated cAMP production was dose-dependently potentiated by PMA, whereas forskolin-stimulated cAMP production was not affected. However, both PTH- and forskolin-stimulated cAMP production was dose-dependently augmented when PMA was added 3 min prior to PTH or forskolin. With increasing preincubation periods (up to 24 h) with PMA instead of a potentiation an inhibition was observed. This inhibition is not due to PTH receptor desensitization, although, on basis of the present results desensitization can not completely be excluded. In all cases 4α-phorbol was without effect. The present results show that protein kinase C modulates stimulation of ODC activity and cAMP production in fetal rat osteoblasts. The modulation of both ODC activity and cAMP production appears to be dependent on the nature of the stimulator. The present data suggest a role for protein kinase C in limiting the cAMP-mediated stimulation of ODC activity in these cells. Furthermore, it is suggested that protein kinase C can interfere at more than one site in the cAMP-generating system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041380315
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  • 6
    Electronic Resource
    Electronic Resource
    Mass spectrometric investigation of some macrocyclic and macroacyclic compartmental schiff bases (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 231-239 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectrometric behaviour of four macroacyclic and five macrocyclic Schiff bases using two ionization methods (electron impact and fast atom bombardment) was studied in detail with the aid of mass-analysed ion kinetic energy (MIKE) spectrometry. It was possible to propose a common electron impact-induced decomposition pattern for the acyclic compounds, whereas for the cyclic compounds, analysed by fast atom bombardment, peculiar fragmentation routes occurred, which were strongly dependent on the macrocyclic structure and on the different side-chains.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210270314
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  • 7
    Electronic Resource
    Electronic Resource
    Pharmacological profile of the substituted beta-lactam L-659,286: A member of a new class of human PMN elastase inhibitors (1989)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 39 (1989), S. 47-53 
    Details
    ISSN: 0730-2312
    Keywords: elastase inhibitors ; β-lactams ; lung damage ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Human polymorphonuclear leukocyte elastase (PMN elastase) is inhibited by L-659, 286 (7α-methoxy-8-oxo-3-[[(1,2,5,6-tetrahydro-2-methyl-5,6-dioxo-1,2,4-triaz-in-3-yl)thio]methyl]-5-thia-1-aza-6R-bicyclo [4.2.O]oct-2-ene-2-pyrrolidine carboxamide-5,-dioxide) with a Ki of 0.4 μM. This inhibition is time-dependent, rapid, and only slowly reversible, with a t1/2 of 〉 3 days at 25°C. L-659, 286 is also highly selective for PMN elastase, as it does not inhibit thrombin, trypsin, papain, plasmin, chymotrypsin, or cathepsin G. L-659, 286 administered intratracheally inhibits lung damage caused by administration via the same route of human PMN elastase into hamsters. In marmosets, L-659, 286 is cleared from blood very rapidly after an intravenous injection but is recovered in bronchoalveolar lavage fluid for several hours after intratracheal administration.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240390106
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  • 8
    Electronic Resource
    Electronic Resource
    Fast-atom bombardment mass spectrometry of new polydentate schiff bases. 1. The case of variously substituted mono-and bis-salicylaldimine derivatives (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 111-119 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The mass spectrometric behaviour of ten variously substituted mono- and bis-salicylaldimine derivatives has been studied by fast-atom bombardment and metastable-ion studies. In general, well detectable protonated molecules are present and fragmentation processes mainly related to aldimine chain cleavages are evidenced. Interesting cyclization reactions leading to particularly stable product ions are discussed.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080121
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  • 9
    Electronic Resource
    Electronic Resource
    In vitro fertilization, development, and implantation after exposure of mature mouse oocytes to visible light (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 297-302 
    Details
    ISSN: 1040-452X
    Keywords: Light exposure ; Implantation rate ; IVF ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mature mouse oocytes were exposed prior to in vitro fertilization to visible light during 1, 2, or 4 hr at an intensity of 4,000 lux. Compared to controls cultured under identical conditions but protected from light, exposed eggs did not show any significant modification of cleavage speed are rate. After transfer of blastocysts obtained in vitro in uteri of pseudopregnant females, the implantation rate and the proportion of normal fetuses were not found to be different in relation to preliminary light exposure of oocytes fertilized and cultured in vitro. © 1992 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080330310
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  • 10
    Electronic Resource
    Electronic Resource
    Flow cytometric detection of bicarbonate-induced changes in lectin binding in boar and ram sperm populations (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 164-176 
    Details
    ISSN: 1040-452X
    Keywords: Capacitation ; FITC-lectins ; Spermatozoa ; Cell surface ; Glycoconjugates ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Boar and ram spermatozoa were incubated in Tyrode's medium in the presence or absence of bicarbonate/CO2, a component believed essential for capacitation. At intervals, samples were stained with a range of FITC-lectins to detect changes in surface glycoconjugates, using a rapid staining technique to avoid problems of lectin toxicity. The samples were then analysed directly by flow cytometry, using propidium iodide to distinguish dead cells. In the presence of bicarbonate, a live subpopulation of spermatozoa developed, which in both animal species showed higher binding affinities towards Phaseolus Vulgaris Agglutinin (PHA-E), Sophora Japonica Agglutinin (SJA), and Soybean Agglutinin (SBA), and lower binding affinity towards Erythrina Cristagalli Lectin (ECL). In boar samples, the modified subpopulation reached a maximum after 3 hr incubation, whereas in ram samples it maximized after 1.5 hr. No changes were seen when spermatozoa were incubated in bicarbonate-free medium. The bicarbonate-induced changes in lectin binding were not due to the onset of acrosome reactions, because spermatozoa induced to undergo acrosome reactions with the ionophore A23187 displayed very different lectin-binding patterns. Tested on boar spermatozoa, seminal plasma not only inhibited but reversed the bicarbonate-induced development of the modified subpopulation. EGTA also inhibited development of boar sperm subpopulations; excess Ca2+ was unable to overcome this inhibition, suggesting that multivalent metal ions might be involved in bicarbonate's action. We conclude that bicarbonate causes a loss of surface coating material with affinity for ECL and an unmasking of binding sites for SBA, SJA and PHA-E. A modified subpopulation of live spermatozoa is thereby established, which appears to maximize at a rate in accord with reported capacitation times. © 1995 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080400205
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