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  • viscosity  (6)
  • Alzheimer type dementia  (2)
  • Analytical Chemistry and Spectroscopy  (2)
  • 1
    ISSN: 1435-1463
    Schlagwort(e): Urate ; xanthine ; vascular dementia of the Binswanger type ; Alzheimer type dementia ; Parkinson's disease ; cerebrospinal fluid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We determined the urate and xanthine concentrations in the cerebrospinal fluid (CSF) in patients with vascular dementia of the Binswanger type (VDBT), Alzheimer type dementia (ATD), and Parkinson's disease (PD). We found that the urate concentration was significantly increased in VDBT patients, but significantly decreased in ATD patients compared with controls. The ratio of the concentrations of uric acid (UCSF) to xanthine (XCSF) in the CSF (UCSF/XCSF) had a significant correlation with the ratio of the UCSF to the urate concentration in serum (Userum) (UCSF/Userum) in ATD and PD, whereas UCSF/Userum increased independently of UCSF/XCSF in VDBT. We concluded that the significant increase in the urate concentration in VDBT is mainly due to an impairment of the blood-brain barrier (BBB), and its significant reduction in ATD may reflect impaired brain metabolism.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1435-1463
    Schlagwort(e): Alzheimer type dementia ; vascular dementia of the Binswanger type ; serotonin ; kynurenine ; citalopram ; cerebrospinal fluid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We studied changes in the concentrations of serotonin (5-HT), kynurenine, and other indoleamines in the cerebrospinal fluid of patients with Alzheimer type dementia (ATD) and those with Binswanger type vascular dementia (VDBT), and changes in these indoleamine concentrations 2 weeks after administration of citalopram, a 5-HT uptake inhibitor. The concentrations of total 5-HT (p〈0.005) and kynurenine (p〈0.005) were significantly decreased in ATD patients in comparison to those of the controls. After citalopram administration, there was a remarkable increase in 5-HT concentration (249%, p〈0.0001) and a significant decrease in 5-HIAA concentration (22%, p〈0.02). In the VDBT patients, only 5-HT showed a significant decrease (p〈0.005) in comparison to the control values. It also increased significantly (214%) after citalopram administration. The 5-HT/tryptophan and kynurenine/tryptophan ratios were not correlated for the controls, but did significantly for the ATD and VDBT patients; after citalopram treatment, the increase in 5-HT/tryptophan was correlated significantly with that of kynurenine/tryptophan for ATD, but not for VDBT. These results suggest that both the serotonin and kynurenine pathways are impaired in ATD; whereas, the serotonin pathway alone is in VDBT, and that these impairments are ameliorated by the administration of citalopram.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 12 (1991), S. 105-117 
    ISSN: 1572-9567
    Schlagwort(e): capillary viscometer ; fluorocarbons ; refrigerants ; viscosity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Viscosity measurements were carried out on saturated liquid fluorocarbon refrigerants using an improved capillary viscometer for 11 kinds of fluorocarbon refrigerants; CCl3F (R11), CCl2F2 (R12), CHClF2 (R22), CBrF3 (R13B1), CH3CHF2 (R152a), CCl2FCClF2 (R113), CHCl2CF3 (R123), CHClFCClF2 (R123a), CH3CF3 (R143a), CClF2CCl2F2 (R114), and CH2FCF3 (R134a), in the temperature range from 273 to 353 K. An equation is given to represent the viscosity as a function of temperature.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 14 (1993), S. 45-53 
    ISSN: 1572-9567
    Schlagwort(e): density ; diethylene glycol ; ethylene glycol ; HFC-134a ; polyethylene glycol ; polypropylene glycol ; tetraethylene glycol ; triethylene glycol ; viscosity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Liquid viscosity and density of six binary mixtures of HFC-134a with glycols [ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (400), and polypropylene glycol (2000)] have been measured in the temperature range from 273 to 333 K. The viscosity was measured by a rolling-ball viscometer calibrated with standard liquids of viscosities and densities (JS5, JS10, JS20, and JS50). The density was measured with a glass pycnometer. The uncertainties of the measurements were estimated to be less than 3.4 % for viscosity and 0.04 % for density, respectively. An equation is given to represent the obtained viscosity values as a function of weight fraction and temperature.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 15 (1994), S. 603-626 
    ISSN: 1572-9567
    Schlagwort(e): critical anomaly ; mode-coupling theory ; nitrous oxide ; viscosity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The gaseous viscosity of nitrous oxide (N2O) was measured in the critical region. The experimental temperature range was between 309.650 and 318.150 K and the pressure range was up to 9.6 MPa. The measurements were obtained with an oscillating-disk viscometer, combined with local determination of the density at the position of the oscillating disk, and they have an estimated accuracy of 0.6 % for viscosity and 0.5 % for gas density. The viscosity of N2O exhibits an anomalous increase near the critical point. The anomalous increase in viscosity was analyzed with the viscosity equation proposed by Basu and Sengers.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 16 (1995), S. 773-779 
    ISSN: 1572-9567
    Schlagwort(e): capillary viscometer ; density ; n-butane ; n-hexane ; squalane ; viscosity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Viscosity and density measurements are reported for binary liquid mixtures ofn-butane andn-hexane with squalane in the temperature range from 273 to 333 K. The viscosity measurements have been carried out by using a capillary viscometer calibrated with standard liquids. that is. JS5, JSIO, JS20, and water. The uncertainty in the viscosity data was estimated to be ± 1.7%. The density needed for the calculation of the viscosity has been measured by using a glass pycnometer within an accuracy of ±0.04%. In the prediction of the viscosity, the scheme of Assael et al. fails for mixtures of this type differing greatly in size.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 14 (1993), S. 339-342 
    ISSN: 1572-9567
    Schlagwort(e): density ; HCFC ; HCFC-141b ; HCFC-142b ; HCFC-225ca ; HCFC-225cb ; hydrochlorofluorocarbon ; viscosity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Measurements of saturated liquid viscosities and densities were performed on environmentally acceptable hydrochlorofluorocarbons (HCFCs), CH3CCl2F (HCFC-141b), CH3CClF2 (HCFC-142b; only for viscosity), CF3CF2CHCl2 (HCFC-225ca), and CClF2CF2CHClF (HCFC-225cb), using a capillary viscometer and a glass pycnometer in the temperature range from 273 to 353 K. The uncertainty in the measurement of viscosity is estimated to be 5% based on the comparison of the present data with those in the literature for HCFC-141b. An equation is given to represent our saturated liquid viscosity data as a function of temperature.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 15 (1994), S. 109-115 
    ISSN: 1572-9567
    Schlagwort(e): ethylene glycol ; diethylene glycol ; HFC-134x ; polyethylene glycol(400) ; polypropylene glycol(2000) ; tetraethylene glycol ; triethylene glycol ; viscosity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The liquid viscosity of six binary mixtures of HFC-134a with glycols [ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol(400), and polypropylene glyco](2000)] was measured in the temperature range from 273 to 333 K. The viscosity was measured with an improved capillary viscometer instead of the rolling-ball viscometer reported in our previous work. The measurement uncertainty was estimated to be 1.6%. Most of the present data are higher than previous data, and the gap between the two sets of data increases further in low-viscosity regions. The present results obtained with laminar flow are more reliable than previous results, which are indefinite because of the limit of usefulness of the rolling-ball viscometer in low-viscosity regions.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The methyl ester of trifluoroacetic acid was prepared by reaction with N,N′-dimethylformamide dimethylacetal and was successfully passed through a gas chromatograph. Trifluoroacetic acid was detected by the use of gas chromatography and low and high resolution gas chromatography mass spectrometry in an acidic extract of an incubation medium containing microsomes, reduced nicotinamide adenine dinucleotide phosphate, oxygen and halothane. However, trifluoroacetic acid could not be detected when nicotinamide adenine dinucleotide or oxygen was omitted from the incubation system. From these results, it was proved that halothane is oxidatively metabolized to trifluoroacetic acid by hepatic microsomes.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The combination of a high-performance liquid chromatograph and a magnetic type mass spectrometer with an atmospheric ionization source has been applied for analyses of thermolabile compounds, i.e. antibiotics, amino acids and glycosphingolipids.Chromatography was performed on a 4 mm i.d. x 150 mm column packed with 5 μm ODS at a flow rate of 1 ml min-1. The liquid chromatography/atmospheric pressure ionization (LC/API) magnetic-type mass spectrometer provides not only an abundant pseudo-molecular ion but also fragment ions which give a structural information resulting from collision-induced dissociation at the differential pumping region of the liquid chromatograph/mass spectrometer interface. The isomers of kanamycins could be differentiated from each other on the basis of their mass spectra obtained at the relatively higher drift voltage applied. LC/API mass spectra of leucine and isoleucine were very similar, but it was easy to differentiate one from another by checking the existence of the ions at m/z 43 or m/z 57 in their mass spectra. The LC/API mass spectra of glucosylceramides showed [MH]+ ions of good abundance and significant fragment ions useful for chemical characterization at a proper drift voltage setting in a controlled and reproducible manner.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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