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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 23 (1991), S. S813 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Diffusion and heat treatment experiments in closed ampoules were carried out on two different molecular beam epitaxy-grown GaAs-AlAs superlattice wafers. All of the diffusion experiments were undertaken at 1000° C. The effects of varying the As and S vapour pressures as well as the diffusion time were investigated. Angle-lapping, transmission electron microscopy, X-ray photoelectron spectroscopy and secondary-ion mass spectroscopy were the techniques employed to analyse the samples. It was demonstrated that the diffusion of S enhances the group III interdiffusion or ‘intermixing’ compared with the effect of plain heat treatment. It was also shown that S-induced intermixing has two origins, one being the diffusion of S and its effects on the concentration of native defects and the other being a mechanism related to the formation of a coating on the semiconductor surface during the diffusion.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0495
    Keywords: Organic compounds ; Groundwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract In situ microcosms were successfully used to study the degradation of a range of organic compounds in two pristine aquifers, one aerobic (Vejen) and one anaerobic (Villa Farm). Degradation and sorption behavior in the laboratory column microcosms packed with Villa Farm sediment was very similar to that in the in situ microcosms. However, when the columns were packed with quartz and equilibrated with aerated Villa Farm groundwater, behavior mirrored that at Vejen, indicating that oxygen rather than sediment or groundwater composition was the critical parameter. The aromatic and polyaromatic compounds (benzene, toluene,o-xylene, naphthalene) degraded under aerobic conditions only. The organochlorine compounds (trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, 1,4-dichlorobenzene and 1,2-dichlorobenzene) showed little or no sign of degradation either aerobically or anaerobically. Interpretation of the data was complicated by strong sorption to the Villa Farm sediment but tetrachloromethane, nitrobenzene, ando-nitrophenol appeared to degrade under anaerobic conditions only. Phenol degraded rapidly under both sets of conditions.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0495
    Keywords: Key words: Organic compounds ; Groundwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract . In situ microcosms were successfully used to study the degradation of a range of organic compounds in two pristine aquifers, one aerobic (Vejen) and one anaerobic (Villa Farm). Degradation and sorption behaviour in the laboratory column microcosms packed with Villa Farm sediment was very similar to that in the in situ microcosms. However, when the columns were packed with quartz and equilibrated with aerated Villa Farm groundwater, behaviour mirrored that at Vejen, indicating that oxygen rather than sediment or groundwater composition was the critical parameter. The aromatic and polyaromatic compounds (benzene, toluene, o-xylene, naphtalene) degraded under aerobic conditions only. The organochlorine compounds (trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, 1,4-dichlorobenzene and 1,2-dichlorobenzene) showed little or no sign of degradation either aerobically or anaerobically. Interpretation of the data was complicated by strong sorption to the Villa Farm sediment but tetrachloromethane, nitrobenzene, and o-nitrophenol appeared to degrade under anaerobic conditions only. Phenol degraded rapidly under both sets of conditions.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A detailed study of the effect of rapid thermal annealing in a N2 or Ar atmosphere on the properties of thin GaN layers grown by molecular-beam epitaxy on sapphire substrates was performed. After rapid thermal annealing, an enhancement of the crystal quality of such films was observed. Low-temperature photoluminescence measurements revealed a substantial increase in impurity recombination near the fundamental absorption edge after a rapid high-temperature anneal in a nitrogen atmosphere. A significant decrease in the impurity photoluminescence of the GaN films with protective SiO2 coatings was observed following the anneals.
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  • 6
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 11 (1977), S. 101-105 
    ISSN: 1432-1041
    Keywords: Spironolactone ; potassium canrenoate ; fludrocortisone ; kaliuresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The activity of two aldosterone antagonists in reversing the urinary electrolyte changes induced by the mineralocorticoid fludrocortisone was examined in healthy subjects. Between 2–10 h after treatment there were dose-related increases in sodium excretion and the urine log 10 Na/K ratio, but no significant changes in urine volume, potassium concentration, or potassium excretion. Between 12–16 h after treatment there were dose-related increases in urine sodium excretion and the log 10 Na/K ratio. Unexpectedly, there were significant dose-relatedincreases in potassium excretion despite significant dose-related reductions in urinary potassium concentration. The paradoxical increases in potassium excretion were attributed to dose-related increases in urine volume in the same period. These observations may explain the increased potassium excretion occasionally observed during clinical use of aldosterone antagonists and suggest that potassium excretion in man is influenced by the urine flow rate.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 10 (1976), S. 43-48 
    ISSN: 1432-1041
    Keywords: Spironolactone ; acetylsalicylic acid ; fludrocortisone ; kinetics ; pharmacology ; interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of 600 mg acetylsalicylic acid (ASA) on the renal excretion and clearance of canrenone, the principal unconjugated metabolite of spironolactone, was examined in a double-blind crossover study in six healthy subjects. ASA significantly reduced the urinary excretion, and the fractional excretion, of canrenone between 4 — 6 hours after administration of 50 mg spironolactone. The pharmacological activity of spironolactone, assessed simultaneously by alterations in fludrocortisone-induced urinary electrolyte changes, was slightly but not significantly reduced. The reductions in urinary canrenone excretion correlated with changes in the urinary log 10 Na/K ratio. The results suggest that canrenone may be actively secreted at the proximal renal tubule, and that secretion is blocked by ASA or its conjugates. This is a possible mechanism for the pharmacological interaction between ASA and spironolactone which has been described previously.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 417-424 
    ISSN: 1572-8943
    Keywords: HDPE ; quench cooling ; TREF
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In a previous paper we discussed co-crystallization in a LDPE/HDPE blend using TREF and DSC. As part of that study it was observed that pure HDPE showed an unexpected fractionation behavior when quench crystallized in TREF. The overall peak broadened and two peaks appeared instead of the previously observed single peak for slow cooled HDPE. The development of two peaks was observed for all commercial HDPEs investigated, independent of their melting indices and densities. TREF and GPC were used in an attempt to evaluate the origin of the two HDPE components.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 31 (1986), S. 875-881 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Ständige Versuche zur Identifizierung kompatibler und nichtkompatibler Gemische haben die Notwendigkeit mit sich gebracht, sich überlappende Kurven oder Peaks in thermischen Kurvenverläufen zu trennen. Eine Möglichkeit dafür bietet die Registrierung difierenzieller Kurven. Diese können mit den meisten modernen Geräten aufgenommen werden, ihre Brauchbarkeit wird aber oft durch den Geräuschpegel im System limitiert. Der Geräuschpegel kann durch digitale Filterung und durch Fourier-Transformation der Daten herabgesetzt werden. Beide Methoden wurden unter Verwendung identischer Datenserien geprüft. Die FT-Methode scheint bessere Möglichkeiten zu bieten, geeignete Differentialkurven aus starkes Rauschen aufweisenden Kurvenverläufen zu erhalten.
    Abstract: Резюме Продолжающиеся попы тки идентифицироват ь совмещающиеся и несо вмещающиеся смеси показали необх одимость разделения в термическом анализе накладывающихся дру г на друга кривых или пико в. Одним из способов ре шения этой задачи является дифф еренцирование таких кривых. Хотя так ая возможность имеет ся в самых современных термиче ских аналитических систе мах, однако полезност ь ее ограничивается нали чием больших шумов. Методами, которые мог ут помочь значительн о уменьшить шум, являются математ ическая фильтрация и фурье-пр еобразование данных. Оба метода были использованы дл я данных с одинаковым уровнем ш ума. Метод фурье-преоб разования обладает большими во зможностями для получения требуе мых производных крив ых.
    Notes: Abstract Continued efforts to identify compatible or incompatible blends have demonstrated a need to separate overlapping curves or peaks in a thermal trace. One way to do this is by using the derivatives of these curves. While the function is available on most modern thermal analysis units, its usefulness is often limited by noise in the system. Two techniques which can help to greatly reduce noise are digital filtering and Fourier transformation of the data. Both approaches have been used on identical sets of noisy data. The FT method appears to offer greater potential for producing useful derivatives from noisy composite curves.
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