Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Die vorliegende Arbeit befaßt sich mit dem Stofftransport zwischen einem vertikalen Rieselfilm über eine beheizte Platte und einem kondensierenden Film über eine parallele gekühlte Platte, wobei im Spalt dazwischen Diffusion auftritt. Dies ist ein typischer Fall für einen Destillationsprozeß in einer Diffusionsanlage. Es werden die Bilanzgleichungen für Masse, Impuls und Energie für den verdampfenden Film, den Diffusionsspalt und den kondensierenden Film zusammen mit den Bedingungen für die Grenzschicht und für die Phasengrenzflächen betrachtet. Für die numerische Lösung des Problems und für die Berechnung der Verteilung von Geschwindigkeit und Temperatur im Spalt wird eine örtliche Simulationstechnik verwendet. Es wird eine umfassende Analyse über die Einflüsse von Verdampfungstemperatur, Kondensationstemperatur und Abmessungen des Diffusionsspaltes zur Berechnung des diffusiven Mengenstromes und des Wärmeübergangskoeffizienten infolge Verdampfung vorgenommen. Weiterhin wird das Verhalten von Luft- und Heliumdiffusion im Spalt behandelt. Die analytischen Ergebnisse werden experimentell verifiziert.
    Notes: Abstract The present work deals with mass transfer between a vertical falling film over a heated plate and a condensing film over a parallel cooled plate in a diffusion gap. This is typically the case of the distillation process in a diffusion still. The governing equations for mass, momentum, and energy are considered for the evaporating film, the diffusion gap, and the condensing film, together with the boundary and interfacial conditions. The local similar technique is used to solve the problem numerically and to get the velocity and temperature distributions in the gap. A comprehensive analysis of the effect of evaporating temperature, condensing temperature, and diffusion gap width over the diffusion mass flow rate and evaporation heat transfer coefficient are carried out. Performance charts of air and helium diffusion gaps are given. Additionally, the analytical results are experimentally validated.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Es wird die Wirbelschichtleistung untersucht, wenn diese an einen parabolischen Solarkonzentrator gekoppelt ist. Die Methode benutzt das eindimensionale Wirbelschichtmodell in Verbindung mit einem Solarkonzentrator-Empfänger-Modell. Eine analytische Untersuchung der verschiedenen Auslegungsparameter, wie z. B. die Konzentrationsrate, die Blende des Konzentrators und die Größe der Wirbelschicht wird durchgeführt. Die Ergebnisse werden schließlich benutzt um eine Beziehung zwischen Leistung und Auslegungsparametern zu erhalten, welche dann benutzt werden kann, um die Konstruktion eines Wirbelschicht-Konzentrator-Speichersystems zu optimieren.
    Notes: Abstract The fluidized bed performance is predicted when it is coupled to a solar parabolic concentrator. The prediction method uses the one dimensional fluidized bed model in connection to a solar concentrator-receiver model. An analytical study of the different design parameters such as the concentration ratio, concentrator aperture area and the size of the fluidized bed is presented. The results are then used to obtain a correlation between some performance and design parameters, which can be used to optimize the design of the fluidized bed-concentrator storage system.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit wird das numerische Modell über die Wärmespeicherung in einem Wirbelbett der oben genannten Autoren [5] verbessert und in eine dimensionslose Form umgearbeitet. Das verbesserte Modell basiert auf neuere Experimente bei unterschiedlichen Lufteintrittstemperaturen. Zwischen den numerischen und den experimentellen Ergebnissen wird eine sehr gute Übereinstimmung erzielt. Das neue Modell wird für die Durchführung einer ausführlichen Parameterstudie verwendet. Damit soll der Einfluß der dimensionslosen Parameter (α2, α3 und α4) auf die Leistung des Wirbelbettes bestimmt, sowie die Bedingungen für eine günstige Arbeitsweise des Bettes aufgezeigt, und die Leistung des Wirbelbettes mit der eines Festbettes zu verglichen werden. Die numerischen Ergebnisse werden anhand des zeitlichen Verlaufes der Bett-Temperatur $$\bar \theta _b $$ und des Bett-Wirkungsgrades(η) dargestellt. Der Leistungsverlauf wird für verschiedene Werte der einzelnen Parameter (α2,α3 und α4) angegeben. Die Studie zeigt, daß das Wirbelbett sich für α2 〈 10, α3 〉 30 und α3 〈 10 am günstigsten verhält. Ferner kam man zu dem Ergebnis, daß das Festbett im allgemeinen bei gleicher Bettgröße und gleicher Wärmezufuhr ein besseres Leistungsverhalten bietet.
    Notes: Abstract In the present work, the numerical model developed earlier by the same authors [5] is refined and recast in non-dimensional form. The refined model is calibrated with recent experiments at different bed air-inlet temperatures. Excellent agreement between the numerical results and experiments is obtained. The refined model is then used to conduct an extensive parametric study. The objectives of the parametric study are: (i) to determine the effect of the non-dimensional parameters (α2, α3 and α4) on the bed performance; (ii) to indicate the conditions required for favourable bed operation, and (iii) to compare the fluidized-bed performance with a small-particle packed bed performance. The numerical results are presented as time-histories of average bed temperature ( $$\bar \theta _b $$ ) and bed efficiency(η). The performance histories are given for different value of each parameter (α2, α3, and α4). The study shows that the fluidized bed behaves favourably for α2 〈 10, α3〉 30 and α4 〈 10. Moreover, it was concluded that the small particle packed bed, in general, offers better performance behaviour over a fluidized bed having the same bed size and heat input.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Wärmeübertragung bei gleichzeitiger freier Konvektion und Strahlung in ein Fluid wurde in den letzten Jahren stärker beachtet. Die meisten der bisherigen Arbeiten beschäftigen sich jedoch mit Gasen, während hier Flüssigkeiten behandelt werden. Es werden Berechnungen durchgeführt für eine absorbierende kalte Fluidschicht an einer nicht emittierenden, nicht reflektierenden strahlungsdurchlässige Platte. An der äußeren Oberfläche erfolgen Wärmeverluste an die Umgebung. Die beschreibenden Differentialgleichungen werden dimensionslos dargestellt, die Lösung ist dann von folgenden Parametern abhängig: Dem Absorptionsgrad der Platteα p; der dimensionslosen Längekoordinate der Platteζ; der Prandtl-Zahl der FlüssigkeitPr und dem dimensionslosen Wärmeverlustkoeffizienten an die UmgebungN c. Eine örtliche Nichtähnlichkeitslösung wird angewandt, um Lösungen fürPr=6,5 und einen großen Bereich von αp,C und Nc zu erzielen. Die Ergebnisse zeigten, daß Geschwindigkeits- und Temperaturprofil nicht ähnlich sind und bei kleinen C stark von αp beeinflußt werden. Für große Werte von ζ nimmt der Einfluß von αp ab und für eine Platte ohne Wärmeverluste werden die Geschwindigkeitsprofile ähnlich, d. h. unabhängig von ζ. Der Wärmeverlust von der äußeren Oberfläche der Platte verursacht eine Verschiebung des Temperaturmaximums im Fluid von der Platte weg. Die Ergebnisse zeigen auch, daß der örtliche Wärmeübergangskoeffizient bei Platten ohne Wärmeverluste von der örtlichen Grashof-Zahl mit der Potenz 0.185 abhängt.
    Notes: Abstract Heat transfer by simultaneous free convection and radiation in a participating fluid has received some attention during the past few years. However most of the previous work has been focussed on gases. The present work investigates the problem of combined radiation and natural convection in liquids. Analysis are given for an optically thick cold fluid layer adjacent to a non-emitting and non-reflecting radiation-transmitting plate. The external surface of the plate is subjected to heat loss to surroundings. The governing differential equations are transformed to a dimensionless form where the solution becomes dependent on the following parameters: the plate absorpitivity,α p; the dimensionless distance along the plate,ζ; the fluid Prandtl number,Pr; and dimensionless heat loss coefficient to surrounding,N c. A local non-similar technique is adopted to obtain solutions atPr=6.5 and at a wide range ofα p,ζ, andN c. The results showed that both velocity and temperature are non-similar and they are greatly affected by the value ofα p whenζ is small. At large values of f the effect ofα p diminishes and for a plate without heat loss the velocity becomes similar, i.e. independent of C The heat loss from the external surface of the plate causes the maximum temperature of the fluid to depart far from the plate. The results also showed that for plates without heat loss the local heat transfer coefficient from the plate depends on the local Grashof number to the power 0.185.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple and direct method for the determination of ethinyloestradiol as a minor component in the presence of norethisterone and in oral contraceptive tablets is presented. The method is based on measuring the signal intensity, dδA/dλ and d2δA/dλ 2, of the generated first and second derivative spectra of the δ-absorbance curves obtained by measuring solutions in methanol and methanol-sodium hydroxide at certain wavelengths. The method has been applied to the determination of ethinyloestradiol in oral contraceptive tablets, with a coefficient of variation of less than 2%.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cell-free extracts of 3-4 days old mats of nitrate-grown Penicillium citrinum catalyze the hydrolytic cleavage of the N-glycosidic bonds of inosine, guanosine and adenosine optimally at pH 4, 0.1 M citrate buffer. The same extracts catalyze the hydrolytic deamination of cytidine at a maximum rate in 0.08 M Tris-acetate buffer pH 6.5, 40°C and 50°C were the most suitable degrees for purine nucleoside hydrolysis and cytidine deamination, respectively. The incubation of the extracts at 60°C, in the absence of cytidine caused a loss in the deaminating activity, while freezing and thawing had no effect on both activities. The deaminating activity seems to be cytidine specific as neither cytosine, adenine, adenosine nor guanosine could be deaminated. Uridine competively inhibited this activity, while ammonia had no effect. The apparent Km value of this enzyme for cytidine was 1.57×10-3M and its Ki value for uridine was 7.8×10-3M. The apparent Km values of the N-glycosidic bond cleaving enzyme for inosine, guanosine and adenosine were 13.3, 14.2 and 20×10-3 M, respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Pulsatile flow of blood through a porous medium has been studied studied underthe influence of body acceleration. With the help of Laplace and finite Hankeltransforms, analytic expressions for axial velocity, fluid acceleration, flow rate,and shear stress have been obtained.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2018-01-23
    Description: Analytical Chemistry DOI: 10.1021/acs.analchem.7b04008
    Print ISSN: 0003-2700
    Electronic ISSN: 1520-6882
    Topics: Chemistry and Pharmacology
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2018-08-02
    Description: Contrary to other anticancer targets, topoisomerase I (TOP1) is targeted by only one chemical class of FDA-approved drugs: topotecan and irinotecan, the derivatives of the plant alkaloid, camptothecin. The indenoisoquinolines LMP400, LMP744, and LMP776 are novel noncamptothecin TOP1 inhibitors in clinical trial, which overcome the limitations of camptothecins. To further improve metabolic stability, their methoxy groups have been replaced by fluorine, as in the fluoroindenoisoquinolines NSC 781517 (LMP517), NSC 779135 (LMP135), and NSC 779134 (LMP134). We tested the induction and stability of TOP1 cleavage complexes (TOP1cc), and the induction and persistence of DNA damage measured by histone H2AX phosphorylation (H2AX) compared with their parent compounds LMP744 and LMP776 in leukemia CCRF-CEM and colon carcinoma HCT116 cells. The fluoroindenoisoquinolines induced TOP1cc and H2AX at nanomolar concentrations, and at higher levels than the parent indenoisoquinolines. The fluoroindenoisoquinoline LMP135 showed greater antitumor activity than topotecan in small-cell lung cancer cell H82 xenografts. It was also more potent than topotecan in the NCI-60 cancer cell line panel. Bioinformatics tools ( http://discover.nci.nih.gov/cellminercdb ) were used to investigate the following: (i) the correlations of fluoroindenoisoquinolines activity with other drugs, and (ii) genomic determinants of response in the NCI-60. The activity of the fluoroindenoisoquinolines was mostly correlated with camptothecin derivatives and the parent indenoisoquinolines, consistent with TOP1 targeting. Genomic analyses and activity assays in CCRF-CEM SLFN11 –deleted cells showed that SLFN11 expression is a dominant determinant of response to LMP135. This study shows the potential value of the fluoroindenoisoquinolines for further development as novel anticancer agents targeting TOP1. Mol Cancer Ther; 17(8); 1694–704. ©2018 AACR .
    Print ISSN: 1535-7163
    Electronic ISSN: 1538-8514
    Topics: Medicine
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...