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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 394-397 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In situ UV/VIS/near-IR diffuse reflectance spectroscopy can be carried out on catalysts with a suitable microreactor at temperatures up to 673 K. The experimental difficulties in the application of such a reactor at higher temperatures could be solved as follows. Integrating sphere and reactor are connected by a ceramic part of high reflectivity and low thermal conductivity, i.e., the integrating sphere is enlarged. The signal/noise ratio increases by a factor of 2. The standard IR detector was replaced by a temperature-stabilized version. In addition watercooling jackets were mounted at the integrating sphere. The signal/noise ratio in the near-IR region was thus improved by a factor of 2–3 with a very good reproducibility of measurements. To overcome an alteration of catalyst spectra by thermal radiation, a series of reference spectra of quartz powder (SiO2) were recorded at several temperatures. These spectra are used to correct the catalyst spectra by dividing catalyst and SiO2 spectra. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Journal of Luminescence 60-61 (1994), S. 16-20 
    ISSN: 0022-2313
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Journal of Luminescence 60-61 (1994), S. 16-20 
    ISSN: 0022-2313
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Journal of Luminescence 31-32 (1984), S. 409-411 
    ISSN: 0022-2313
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Physica B: Physics of Condensed Matter 201 (1994), S. 572-574 
    ISSN: 0921-4526
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Physik
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-1440
    Schlagwort(e): Blood pressure ; Catecholamines ; Eicosapentaenoic acid ; Essential hypertension ; Intracellular free calcium ; Lipids ; Platelets
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In a randomized, double-blind, crossover study our specific aim was to examine the effects of a dietary fish oil or olive oil supplementation on blood pressure, intracellular free platelet calcium, plasma lipoproteins, and circulating vasoactive substances such as norepinephrine, epinephrine, and renin in patients with essential hypertension. Ten hypertensive patients (WHO classes I, II) were randomly assigned to receive 9 g fish oil or 9 g olive oil daily for 6 weeks after a 4-week baseline period. The 6-week treatment periods were separated by a 4-week wash-out. During treatment with fish oil diastolic blood pressure decreased from 103±1 to 98±2 mmHg (P〈0.05) but did not change significantly during olive oil intake. Systolic blood pressure was not affected by either treatment. Intracellular free platelet calcium decreased in patients receiving fish oil (from 102±8 nM to 86±6 nM, P 〈 0.05) but was not significantly altered by olive oil treatment. In contrast, the dose-response curve for thrombin-induced intracellular free platelet calcium was not altered by the fish oil enriched diet. Plasma triglycerides decreased by approximately 40% in the fish oil group while low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and total cholesterol were not altered. Renin activity, norepinphrine, and epinephrine in plasma were not influenced by fish oil supplementation. We conclude that a moderate increase in dietary fish oil reduces diastolic blood pressure, intracellular free platelet calcium, and plasma triglycerides in patients with essential hypertension. The decrease in basal intracellular free platelet calcium concentration does not seem to be due to a diminished responsiveness of the calcium messenger system to thrombin.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 57 (1993), S. 167-169 
    ISSN: 1432-0630
    Schlagwort(e): 78.55.Et ; 07.20.Mc ; 44.30.+v
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A bistable heating of samples is found in liquid helium. Using the strong temperature dependence of the no-phonon doublet of the 4 T 1(G) → 6 A 1(S) emission of the ZnSe:Cr+ centre, the temperature can be determined in the excited volume. Temperature jumps of about 5 K are recorded. The cause for the bistable crystal heating lies in the transition from the nucleate boiling to the film boiling state of the helium. In this process, the heat transfer is drastically reduced and thus the sample is further heated.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 55 (1994), S. 473-478 
    ISSN: 1432-0827
    Schlagwort(e): Strain ; Rat tibia ; c-fos ; Alkaline phosphatase ; Osteocalcin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract Although mechanical forces regulate bone mass and morphology, little is known about the signals involved in that regulation. External force application increases periosteal bone formation by increasing surface activation and formation rate. In this study, the early tibial periosteal response to external loads was compared between loaded and nonloaded contralateral tibia by examining the results of blot hybridization analyses of total RNA. To study the impact of external load on gene expression, RNA blots were sequentially hybridized to cDNAs encoding the protooncogene c-fos, cytoskeletal protein β-actin, bone matrix proteins alkaline phosphatase (ALP), osteopontin (Op), and osteocalcin (Oc), and growth factors insulin-like growth factor I (IGF-I) and transforming growth factor-β (TGF-β). The rapid yet transient increase in levels of c-fos mRNA seen within 2 hours after load application indirectly suggests that the initial periosteal response to mechanical loading is cell proliferation. This is also supported by the concomitant decline in levels of mRNAs encoding bone matrix proteins ALP, Op, and Oc, which are typically produced by mature osteoblasts. Another early periosteal response to mechanical load appeared to be the rapid induction of growth factor synthesis as TGF-β and IGF-I mRNA levels were increased in the loaded limb with peak levels being observed 4 hours after loading. These data indicate that the acute periosteal response to external mechanical loading was a change in the pattern of gene expression which may signal cell proliferation. The altered pattern of gene expression observed in the present study supports previous evidence of increased periosteal cell proliferation seen both in vivo and in vitro following mechanical loading.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 98 (1995), S. 215-221 
    ISSN: 1434-6036
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Samples of crystalline ZnTe with different concentrations of iron were prepared by the vertical high-pressure Bridgman method. Absorption and emission spectra were recorded at liquid-helium temperature in the region of the5 T 2(D)⇌5 E(D) infrared transitions of substitutional Fe2+(d 6) ions. In the range between 2400 and 2520 cm−1 a rich structure is observed showing more lines than predicted by plain crystal-field theory. The explanation of all these lines is found after introducing a vibronic Jahn-Teller term to the Hamiltonian. A linear coupling between the doubly degenerate vibrational mode ɛ to the electronic orbitals of the ionic multiplet5 D is added to the electronic and vibrational terms of the Hamiltonian. A diagonalization follows using just one free parameter: the Jahn-Teller energy representing the strength of the coupling. The corresponding value is 3 cm−1, which is identical to the one already reported for CdTe∶ Fe2+. The calculated spectrum is in good agreement with the one determined experimentally. Measurements of the absorption spectra support conclusions drawn earlier about a Jahn-Teller coupling also for the excited multiplet. Finally a prediction of how the far-infrared would look like is also given.
    Materialart: Digitale Medien
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  • 10
    ISSN: 0044-2313
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Eigenschaften von Bariumchlorophosphat (Apatit)-Leuchtstoffen bei Aktivierung mit zweiwertigem EuropiumEine Reihe von europiumaktivierten Barium- bzw. Calciumchlorophosphaten wurde in Pulverform dargestellt. Diese Leuchtstoffe sind isomorphe Vertreter der hexagonalen Chlorapatite (Ba, Ca, Mg)10(PO4)6Cl2. Neben Röntgendiffraktogrammen wurden Anregungs- und Emissionsspektren der Lumineszenz bei Zimmertemperatur und bei tiefen Temperaturen (T ∽ 4 K) untersucht. Steigender Calciumanteil beeinflußt die Lumineszenzeigenschaften dieser festen Lösungen durch Veränderung des am Eu2+-Ion wirkenden Kristallfelds. Das Erscheinen einer neuen Emissionsbande mit höherem Ca2+-Gehalt bei tiefen Temperaturen deutet auf Einbau der Eu2+-Ionen auf zwei verschiedenen Ba-Plätzen, so daß zwei Arten von Lumineszenzzentren auftreten. Die Lumineszenz entsteht durch Übergänge von der 4f65d- zur 4f7-Konfiguration des Eu2+.
    Notizen: A series of powder materials of barium and calcium chlorophosphate activated by divalent europium have been prepared. These luminophors are isomorphous representatives of the hexagonal chlorapatites (Ba, Ca, Mg)10(PO4)6Cl2. In addition to x-ray diffractograms, excitation and emission spectra of luminescence have been studied at room and low temperatures (T ∽ 4 K). An increasing calcium content affects the luminescence properties of the solid solutions by changing the crystal field acting upon the Eu2+ ion. The appearance of a new low-temperature emission band with higher Ca2+ content indicates that the Eu2+ ions substitute on two different barium sites thus forming two types of luminescent centres. The luminescence arises from transitions between 4f65d and 4f7 configurations of Eu2+.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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