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  • Chemistry  (3)
  • Microinjection  (1)
  • Oceanography
  • 1980-1984  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Micellar Solubilization of Biopolymers in Hydrocarbon Solvents III. Empirical Definition of an Acidity Scale in Reverse Micelles (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 2302-2311 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper deals with the problem of defining, and measuring, the pH inside the water pool (which we define as pHwp) of reverse micelles, i.e. micelles formed by surfactants dissolved in apolar solvents in the presence of minimal amounts of water. The conceptual and experimental difficulties are discussed, and it is argued that no absolute determination of pHwp is possible, mostly because water in the water pools of reverse micelles is a new solvent, for which no standardization of acidity is available. The problem can be approached only on the basis of an empirical acidity scale.An empirical acidity scale for water pools in reverse micelles of bis (2-ethyl-hexyl) sodium sulfosuccinate (AOT) in isooctane has been defined by measuring the 31P-chemical shifts of phosphate buffers. The chemical shifts in bulk water were compared to those found in reverse micelles under the assumption that the pK of phosphate ion is the same in the two systems. It was found that in most cases there was little difference (less than 0.4 pH units) between pHwp and the pH of the starting buffer in bulk water (which we define as pHst). However, this difference between pHwp and pHst may become much larger in certain cases.The difference (pHwp-pHst) is measured under a variety of conditions, and this permits the determination of an operational acidity in the micelle water pools as a function of the pHst with which the aqueous micelles are prepared. The significance of such data for interpreting the behaviour of enzymes confined in the micelles water pool is discussed. Based on the pHwp scale, the apparent pKa of phenol-red and 4-nitrophenol were determined in reverse micelles containing different buffers and different water content. The pKa values obtained were rather sensitive to changes of both these factors, which was taken to signify that organic dies have only a very limited applicability to measure the acidity of the water pools of reverse micelles.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630820
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  • 2
    Electronic Resource
    Electronic Resource
    Correlation of mitochondrial form and function in vivo: Microinjection of substrate and nucleotides (1982)
    Springer
    Cell & tissue research 227 (1982), S. 129-137 
    Details
    ISSN: 1432-0878
    Keywords: Mitochondria ; Ultrastructure ; Microinjection ; ATP ; ADP ; Amoeba proteus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Microinjection of adenine nucleotides and substrates into the cytoplasm of Amoeba proteus followed by EM examination has been used in an attempt to relate alterations in mitochondrial morphology with functional changes. Contracted mitochondria with dark matrix and wide cristae (Type I), and expanded mitochondria with light matrix and narrower cristae (Type II) coexist in normal active amoebae, but their numbers can be varied according to different cell activity states. Following injection of ATP, the mitochondria of the amoebae showed a time-dependent movement towards a predominately Type II form, whilst injections of ADP produced predominately the Type I form. Injection of succinate or deionised water, even in large amounts, had little effect on the numbers of Type I or Type II forms. The change induced by ATP was of long duration; that induced by ADP was influenced by both concentration injected and the cell's substrate levels. With 3 mM solutions of ADP the mitochondrial population was primarily of Type I organelles; higher ADP concentrations or the simultaneous injection of succinate, however, resulted in a switch with time to increased proportions of Type II mitochondria. The results extend the findings of previous in vivo and in vitro mitochondrial studies and are discussed in the light of these.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00206336
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  • 3
    Electronic Resource
    Electronic Resource
    Epoxy resin cure. II. FTIR analysis (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 3713-3726 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fourier transform infrared (FTIR) spectroscopy is used to determine the cure rate of an epoxy resin consisting of Tetraglycidyl-4,4′-diaminodiphenyl methane (TGDDM) and diaminodiphenylsulfone (DDS). Cure rates at 120 and 160°C are shown to increase noticeably when 1% BF3-MEA is added to either TGDDM to TGDDM plus DDS. Fluoroboric acid is shown to increase the cure rates even more than the BF3-MEA. These Results combined with the NMR results in the accompanying article indicate that BF3-MEA is not a catalyst for epoxy resin cure. Instead it is rapidly hydrolyzed to fluoroboric acid which acts as the catalyst.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070291207
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  • 4
    Electronic Resource
    Electronic Resource
    Epoxy resin cure. I. Fluorine-19 NMR of boron trifluoride monoethylamine and fluoroboric acid (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 3697-3711 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fluorine-19 NMR is used to examine the role of boron trifluoride monoethylamine (BF3-MEA) in epoxy resin cure. Spectra were first recorded in a variety of solvents suitable for dissolving different epoxy resins. All spectra contained a peak due to fluoroboric acid. Spectra of BF3-MEA in orthodichlorobenzene were then recorded at elevated temperatures. The floroboric acid peak area increased, indicating that the BF3-MEA was being hydrolyzed. Results indicate that, at temperatures above 100°C, BF3-MEA is completely hydrolyzed within 5 min to fluoroboric acid.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070291206
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