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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2435-2441 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Powdered samples of the type Ce1−xRExO2−y, where RE=La, Pr, Nd, Eu, Gd, and Tb, are synthesized over the range 0≤x≤0.5 starting from nitrate solutions of the rare earths. X-ray diffraction and Raman scattering are used to analyze the samples. These compounds, at least in the low doping regime and for strictly trivalent dopants, form solid solutions that maintain the fluorite structure of CeO2 with a change in lattice constant that is approximately proportional to the dopant ionic radius. The single allowed Raman mode, which occurs at 465 cm−1 in pure CeO2, is observed to shift to lower frequency with increasing doping level for all the rare earths. However, after correcting for the Grüneisen shift from the lattice expansion, the frequency shift is actually positive for all the strictly trivalent ions. In addition, the Raman line broadens and becomes asymmetric with a low frequency tail, and a new broad feature appears in the spectrum at ∼570 cm−1. These changes in the Raman spectrum are attributed to O vacancies, which are introduced into the lattice whenever a trivalent RE is substituted for Ce4+. This conclusion is supported by a simple model calculation of the effects of O vacancies on the Raman spectrum. The model uses a Green's function technique with the vacancies treated as point defects with zero mass.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4046-4054 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this work fast-changing bias conditions in the nanosecond regime are applied to n-channel metal-oxide-semiconductor field effect transistors. Short bunches of holes are injected into the silicon dioxide (SiO2) and subjected to different field conditions which influence the final trapping. It is shown that by this experiment the kinetics of hole movement in the oxide can be studied. The model of polaron formation originating from work on high-energy irradiation is essentially confirmed. Evidence for a prepolaron formation phase is found, however, with a smaller scattering length for which we propose the different hole formation process in this experiment to be responsible. On this basis the interface trap formation by injected holes is investigated. It is found that not the number of trapped holes but the one of injected holes is decisive for interface trap formation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2171-2173 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is demonstrated that SiC films can be deposited epitaxially on [001] and [111] Si wafers by excimer laser ablation of just a carbon target, in vacuum, at deposition temperatures as low as 1100 °C. Diffraction studies show that the SiC films have the same crystalline orientation as the substrates. The film growth on the Si substrate to thicknesses as large as 4000 A(ring) with no significant excess carbon indicates that in addition to reaction of the carbon in the plume with Si of the substrate, there is transport of Si within the SiC film. For continued deposition beyond this thickness a carbon layer will form. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 113 (1994), S. 0 
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The interaction between varieties and environment can make the prediction of crop performance difficult. The farmer is obviously interested in achieving optimum production within the particular growing environment of his farm, thus, this paper investigates if crop performance predictions can be improved by making information from other locations into account. The investigation is based on yield data from winter wheat resulting from official German variety-performance tests. The predictors are based on the single location (control), unweighted means, principal components, and weighted means, produced using regression coefficients as weights. These predictors were tested on an independent data set from another year. For the given yield data in winter wheat, the overall mean proved to be the best, which suggests that prediction for all locations should be the same, and predictors for specific locations cannot, therefore, be recommended. The main reason for this is the relatively small interaction between genotype and location, in comparison to the second-order interaction between genotypes, locations and years.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 737 (1994), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 29 (1990), S. 289-294 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 7595-7601 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Homogeneous injection of holes into the gate oxide of metal-oxide-semiconductor (MOS) devices was obtained using p-channel MOS transistors under illumination conditions. Because gate hole currents could be measured the dependence of the hole trapping on the oxide electric field and on the energy of the holes at the injection point could be investigated. In contrast to results recently reported for electron injection no evidence for the generation of traps during hole injection was found. Only a small dependence of the capture cross section on the oxide field was observed. The study of the interface state generation during hole injection at various fields revealed that the amount of interface states directly generated by the injected holes is less than 5% of the number of trapped holes. For longer times a transformation process occurs and a correlation is found between the detrapping of holes and the generation of interface states.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 29 (1990), S. 39-46 
    ISSN: 1436-6215
    Keywords: thiamine (vitaminB 1) ; pregnancy ; intrauterine growth retardation (IUGR) ; Thiamin (Vitamin B1) ; Schwangerschaft ; intrauterineMangelentwicklung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Der Gehalt an Thiamin (Vitamin B1) wurde im mütterlichen Blut jeweils in den Blutzellen und im Plasma bei normalem Schwangerschaftsverlauf und bei Schwangerschaft mit intrauteriner Mangelentwicklung des Feten bestimmt. Die Bestimmung der Thiaminkonzentration erfolgte mit der Thiochrom-Methode mittels HPLC-Trennung und anschließender fluorimetrischer Bestimmung nach der Methode von Weber et al. (2). Bei normalem Schwangerschaftsverlauf ist ein Abfall des Thiamingehalts in den Blutzellen von 230 nmol/l bis 170 nmol/l von der 28. bis zur 39. Schwangerschaftswoche zu beobachten. Bei schwerer intrauteriner Mangelentwicklung ist nur ein geringer Abfall des Thiamingehaltes von 140 nmol/l in der 30. Schwangerschaftswoche bis zu einem Gehalt von 130 nmol/l in der 39. Schwangerschaftswoche zu beobachten. Demgegenüber bleiben die Thiaminwerte in Plasma annähernd konstant. Um die Thiaminkonzentrationen bei normaler Schwangerschaft und bei schwerer intrauteriner Mangelentwicklung zu vergleichen, führten wir eine Einteilung in zwei Gruppen — eine von 28/0 bis 34/6 und eine von 35/0 bis 39/6 Schwangerschaftswochen durch. In beiden Gruppen waren die Thiaminwerte in den Blutzellen bei normaler Schwangerschaft signifikant höher als bei intrauteriner Mangelentwicklung (p=0,0001 und p=0,0005). Die Thiaminwerte im Plasma unterschieden sich jedoch nicht signifikant bei normalem Schwangerschaftsverlauf und bei Schwangerschaften mit intrauteriner Mangelentwicklung. Unsere Ergebnisse deuten darauf hin, daß mütterlicher Thiaminmangel einen Grund für eine intrauterine Mangelentwicklung darstellt.
    Notes: Summary The concentration of thiamine (vitamin B1) was measured in blood cells and plasma from mothers with normal pregnancy and from mothers whose pregnancy was complicated by intrauterine growth retardation (IUGR). Thiamine concentrations were estimated by the thiochrome method using HPLC separation and fluorimetric detection according to Weber et al. (2). During normal pregnancies the thiamine values in blood cells fall in the 28th to the 39th week of gestation from 230 nmol/l to 170 nmol/l. In cases with severe IUGR there is only a slight decrease in the thiamine levels from 140 nmol/l in the 30th week of gestation to a level of 130 nmol/l in the 39th week of gestation. During this period the thiamine values in plasma remain constant. To compare the thiamine concentrations in normal pregnancies and in those with IUGR we separated the thiamine values in a group from 28/0 to 34/6 and one from 35/0 to 39/6 weeks of gestation. In both groups mothers with normal pregnancy had significantly higher thiamine levels in the blood cells than mothers whose pregnancy was complicated by IUGR (p=0.0001 and p=0.0005). However, the thiamine values in plasma were not significantly different in normal pregnancies and pregnancies with IUGR. The results indicate that maternal thiamine deficiency might be one cause of IUGR.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    International journal of legal medicine 103 (1990), S. 313-313 
    ISSN: 1437-1596
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Type of Medium: Electronic Resource
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