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  • 1
    Electronic Resource
    Electronic Resource
    Degradation of dielectric breakdown field of thermal SiO2 films due to structural defects in Czochralski silicon substrates (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7944-7957 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We used heat treatment to intentionally introduce various structural defects in Czochralski silicon substrates. The type, size, and number density of the induced defects were surveyed with transmission electron microscopy, and the defects were then incorporated into SiO2 films (10–50 nm thick) during thermal oxidation in dry O2. The effect of the defects on dielectric strength of the SiO2 films was examined with a time zero dielectric breakdown method. Larger platelet oxygen precipitates caused greater decreases of the breakdown field, and precipitates smaller than the SiO2 film thickness did not appreciably reduce the breakdown field. Every large platelet oxygen precipitate incorporated in the SiO2 film caused a degradation. Octahedral oxygen precipitates caused little degradation. The breakdown field was higher than 7 MV/cm and did not depend much on the SiO2 film thickness and precipitate size. We discussed possible mechanisms for the degradation due to both kinds of precipitates. Oxidation-induced stacking faults formed by a surface oxidation did not markedly reduce the breakdown field when only segments of dislocations and stacking faults were incorporated in the SiO2 film. Another serious degradation was caused by pits that were formed by dissolving octahedral oxygen precipitates in a HF solution. The breakdown field was lower for thicker oxide films, and it recovered as the pit shape became smoother during chemical etching. We proposed that this degradation was caused by a local thinning of SiO2 film due to stress generated in the oxidation of pits. These results suggest that voids rather than the other reported grown-in defects play the most important role in the degradation observed for as-grown silicon. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362344
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  • 2
    Electronic Resource
    Electronic Resource
    Adult onset globoid cell leukodystrophy (Krabbe disease): analysis of galactosylceramidase cDNA from four Japanese patients (1997)
    Springer
    Human genetics 〈Berlin〉 100 (1997), S. 450-456 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We examined galactosylceramidase (GALC) cDNA in four Japanese patients with adult onset globoid cell leukodystrophy (Krabbe disease; AO-GLD) by polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analysis, subsequent sequence determination, and restriction enzyme digestion of PCR products. Initial symptoms were the onset of slowly progressive spastic paraplegia from the middle of the second decade, and all patients had diminished GALC activity in their leukocytes. We identified three missense mutations (I66M, G270D, L618S) and one exon-6 skipping (535– 573del). Two of the patients had only the I66M mutant mRNA, and one only the G270D mutant mRNA. The fourth patient carried a compound heterozygous mutation of 535–573del and L618S. To determine the enzymatic activities produced by these mutations, we constructed mutated GALC cDNAs and expressed them in COS-1 cells. Three mutations, viz., G270D, L618S, and exon-6 skipping (535–573del), produced diminished GALC activity as expected. The I66M mutation in the wild-type GALC cDNA(I289) had normal activity, but when this mutation and the V289 polymorphism were introduced into the same allele, it had decreased activity. Thus, the combination of a unique mutation and polymorphism causes conformational change in the GALC enzyme, resulting in low enzymatic activity. AO-GLD mutations, including those found here, are located in the N-terminus (I66M, G270D, 535–573del) or C-terminus (L618S) of the GALC enzyme, whereas the reported mutations in the infantile form (IF-GLD) are in the central domain. This difference in mutation sites may affect the clinical features of GLD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004390050532
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  • 3
    Electronic Resource
    Electronic Resource
    Additional mechanisms of nafamostat mesilate-associated hyperkalaemia (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 149-151 
    Details
    ISSN: 1432-1041
    Keywords: Key words Nafamostat mesilate ; Haemodialysis; anticoagulant ; hyperkalaemia ; erythrocyte ; potassium ; 6-amidino-2-naphthol ; p-guanidinobenzoic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: Nafamostat mesilate, a potent protease inhibitor, is widely used for the treatment of pancreatitis, disseminated intravascular coagulation and as an anticoagulant in haemodialysis. However, hyperkalaemia associated with nafamostat mesilate has been reported. It is thought to be due to decreased urinary potassium excretion, of the drug suppression of aldosterone secretion, and a direct inhibitory action on the apical Na+ conductance in collecting ducts. We have seen two cases of nafamostat mesilate associated-hyperkalaemia, which indicated that extrarenal potassium imbalance might play a role in inducing hyperkalaemia. Methods: To examine the effect of nafamostat mesilate on potassium transport in erythrocytes in vitro, 86RbCl uptake was measured in red blood cells from eight healthy volunteers. Results: Nafamostat mesilate and a metabolite, 6-amidino-2-naphthol, at concentrations of 10−4 and 10−3 M, respectively, significantly, suppressed potassium influx whilst another metabolite, p-guanidinobenzoic acid, had no effect. The inhibitory action of nafamostat mesilate was not affected by various inhibitors. Conclusion: Nafamostat mesilate and its metabolite, 6-amidino-2-naphthol, suppressed potassium influx in erythrocytes by inhibition of a Na-K ATPase dependent pathway, which was not inhibited by amiloride, barium, nor by frusemide (furosemide).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050176
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  • 4
    Electronic Resource
    Electronic Resource
    Placing actuators on space structures by genetic algorithms and effectiveness indices (1995)
    Springer
    Structural and multidisciplinary optimization 9 (1995), S. 69-75 
    Details
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Genetic algorithms are a powerful tool for the solution of combinatorial problems such as the actuator placement problem. However, they require a large number of analyses with correspondingly high computational costs. Therefore, it is useful to tune the operators and parameters of the algorithm on simple problems that are similar to more complex and computationally expensive problems. The present paper employs an easy-tocalculate measure of actuator effectiveness to evaluate several genetic algorithms. Additionally, the effects of population size and mutation rates are also investigated for a problem of placing actuators at 8 of 1507 possible locations. We find that even with the best of the algorithms and with optimum mutation rates, tens of thousands of analyses are required for obtaining near optimum locations. We propose a procedure that estimates the effectiveness of the various locations and discards ineffective ones, and find it helpful for reducing the cost of the genetic optimization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01758822
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  • 5
    Electronic Resource
    Electronic Resource
    Thermodynamics and molecular ordering of carbonate-type dimer liquid crystals with emphasis on the geometrical characteristics of the linking group (1995)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 46 (1995), S. 437-444 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mainchain liquid crystals having a regularly alternating rigid-flexible repeating structure often exhibit distinct odd-even oscillation in their thermodynamic quantities with respect to the number of methylene units in the spacer. The effect has been widely observed from dimer (DLC) to polymer liquid crystals (PLC), but not in the monomer liquid crystals (MLC) which comprise a mesogenic unit carrying one or two tails. The degree of oscillation varies depending on the chemical structure of the linking group used to join the spacer with mesogenic units. In our previous work, we have suggested that such characteristics are mainly due to the geometrical arrangement of the linkage. In this work, we have prepared a series of carbonate-type MLCs NCφφOCOO(CH2)n - 1CH3, where φ is a phenyl group, as well as DLCs NCφφOOCO(CH2)nO-COOφφCN. The thermodynamic behaviors at the nematic-isotropic NI transition have been compared with those previously reported for the ether-type DLCs. For the dimer series, the molecular orientation and the spacer conformation were investigated by using 2H NMR technique. The origin of the difference in the odd-even behaviors has been traced back to the geometrical characteristics of the linking groups, which affect the relative orientation of the terminal mesogenic cores, thus leading to modification of the conformational distribution in the nematic state. The analysis has yielded the nematic conformation which satisfactorily reproduces the observed values of the dipolar and quadrupolar couplings. The bond conformation vs. bond order plots are shown for the n odd and n even systems together with the corresponding results derived previously for the ether-type DLCs. Although the numbers of bonds of the flexible spacer are not exactly comparable with each other, the conformational ordering along the spacer tends to be pronounced in both DLC systems.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1995.010460606
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