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  • Physical Chemistry  (5)
  • Key words: Computed tomography – Magnetic resonance imaging – Acute pancreatitis – Chronic pancreatitis  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Pancreatitis: computed tomography and magnetic resonance imaging (2000)
    Springer
    European radiology 10 (2000), S. 401-408 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Computed tomography – Magnetic resonance imaging – Acute pancreatitis – Chronic pancreatitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The value of CT in management of severe acute pancreatitis is well established. Some, but not all, experimental studies suggest a detrimental effect of intravenous iodinated contrast agents in acute pancreatitis, but although initial clinical data tends to support this, the positive advantages of enhanced CT outweigh the possible risks. Magnetic resonance imaging has been shown to be as effective as CT in demonstrating the presence and extent of pancreatic necrosis and fluid collections, and probably superior in indicating the suitability of such collections for percutaneous drainage. Image-guided intervention remains a key approach in the management of severely ill patients, and the indications, techniques and results of radiological intervention are reviewed herein. Both CT and MRI can be used to diagnose advanced chronic pancreatitis, with the recent addition of MRCP as a viable alternative to diagnostic endoscopic retrograde cholangiopancreatography (ERCP). Both MRCP and CT/MR imaging of the pancreatic parenchyma still have limitations in the recognition of the earliest changes of chronic pancreatitis – for which ERCP and tests of pancreatic function remain more sensitive – but the clinical significance of these minor changes remains contentious.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050066
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics of the reactions of cyclopropane derivatives, part II. The gas-phase pyrolysis of cyclopropylamine (1973)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 5 (1973), S. 27-35 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: At temperatures of 356-425°C and pressures of 15-60 Torr, cyclopropylamine reacts to give an equimolar mixture of ammonia and N-propylidenecyclopropylamine as the initial product. The reaction is first order, homogeneous, and unaffected by the presence of radical inhibitors, and thus proceeds by an initial rate-determining unimolecular isomerization to give a reactive intermediate, which then reacts with a further molecule of cyclopropylamine to give the observed products. Reaction in the presence of added aliphatic amines gives other imines in addition, and the nature of these indicates that the intermediate is propenylamine or its tautomer propylideneamine:
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550050103
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics of the reactions of cyclopropane derivatives. V. The gas-phase unimolecular reactions of 1 α-chloro-2α,3α-dimethylcyclopropane and 1α-chloro-2α,3β-dimethylcyclopropanePreliminary communications, see [7]; Part IV, D. A. Luckraft and P. J. Robinson, Int. J. Chem. Kinet., 5, 329 (1973) (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 937-950 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermolysis of the “all-cis” compound 1α-chloro-2α,3α-dimethylcyclopropane (A) at 550-607 K and 6-115 torr is a first-order homogeneous non-radical-chain process giving penta-1,3-diene (PD) and HCl as products. The Arrhenius parameters are log10A(sec-1) = 13.92 ± 0.08 and E = 199.6 ± 0.9 kJ/mol. The isomer with trans-methyl groups, 1α-chloro-2α,3β-dimethylcyclopropane (B) reacts by two parallel first-order processes giving as observed products trans-4-chloropent-2-ene (4CP) and PD + HCl, with log10A(sec-1) = 14.6 and 13.8, respectively, and E = 199.5 and 190.2 kJ/mol, respectively. The 4CP undergoes secondary decomposition to PD + HCl (as investigated previously). Comparison of the results for compounds (A) and (B) with those for other gas-phase and solution reactions leads to the conclusion that the gas-phase thermolyses proceed by rate-determining ring opening to form olefins which may decompose further by thermal or chemically activated reactions, and that the ring opening is a semiionic electrocyclic reaction in which alkyl groups in the 2,3-positions trans to the migrating chlorine semianion move apart, with appropriate consequences for the rate of reaction and the stereochemistry of the products.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550110902
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  • 4
    Electronic Resource
    Electronic Resource
    A simple nondestructive method of determining the volume of dead space in a gas-kinetic apparatus (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 9 (1977), S. 503-505 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550090317
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetics of the reactions of cyclopropane derivatives. III. Gas-phase unimolecular isomerization of cyclopropyl cyanide to the cyanopropenes (1973)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 5 (1973), S. 137-147 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclopropyl cyanide isomerizes in the gas phase at 660°-760°K and 2-89 torr to give mainly cis- and trans-crotonitrile and allyl cyanide, with traces of methacrylonitrile. The reactions are first order, homogeneous, and unaffected by the presence of radical-chain inhibitors. The rate constants are given by Overall: \documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} k/{\rm sec}^{ - 1} = (14.58 \pm 0.08) - (242.0 \pm 1.2){\rm kJ}\,{\rm mole}^{ - 1} /2.303RT$$\end{document} cis-Crotonitrile: \documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} k/{\rm sec}^{ - 1} = (14.01 \pm 0.11) - (237.6 \pm 1.4){\rm kJ}\,{\rm mole}^{ - 1} /2.303RT$$\end{document} trans-Crotonitrile: \documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} k/{\rm sec}^{ - 1} = (14.09 \pm 0.07) - (243.7 \pm 0.9){\rm kJ}\,{\rm mole}^{ - 1} /2.303RT$$\end{document} Allyl cyanide: \documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} k/{\rm sec}^{ - 1} = (14.59 \pm 0.13) - (252.0 \pm 1.8){\rm kJ}\,{\rm mole}^{ - 1} /2.303RT$$\end{document} where the error limits are standard deviations. On the basis of a biradical mechanism, it is deduced that the —CH—CN radical center is resonance stabilized by ca. 30 kJ mole-1. Approximate equilibrium data are given for interconversion of the 1- and 3-cyanopropenes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550050112
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetics of the reactions of cyclopropane derivatives. IV. Kinetic isotope effect in the isomerisation of cyclopropylamine (1973)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 5 (1973), S. 329-331 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The high-pressure isotopic rate ratio kH/kD for isomerisation of cyclopropylamine and cyclopropylamine-N-d2 is 1.06 at 649-678 K, supporting a mechanism which does not involve migration of hydrogen from the amine group in the rate-determining step.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550050303
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