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  • Chemistry  (2,030)
  • FLUID MECHANICS AND HEAT TRANSFER  (187)
  • 1975-1979  (2,217)
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 9 (1975), S. 127-142 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A thermodynamic approach to the problem of platelet adsorption out of a suspension on to a smooth and homogeneous solid surface is developed. The interfacial tension values required may be estimated from contact angle data by means of an equation of state relation. According to the thermodynamic approach the functional dependence of platelet adsorption on surface tension of the solid differs according to whether the surface tension of the platelets is smaller or larger than the surface tension of the liquid in which they are suspended. The implications of this thermodynamic approach in situations where plasma proteins are present and the biomaterials surfaces may be heterogeneous and rough are discussed. Previous analyses using the critical surface tension of wetting and other surface-related parameters are compared with the thermodynamic analysis given here.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 543-549 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From deuterium labelling experiments it was concluded that metastable molecular ions of ethyl methyl sulfide lose a methyl radical with the formation of both [CH3S=CH2]+ amd [CH3CH=SH]+· The fragmentation reactions of metastable ions generated with these structure are losses of C2H2, H2S and CH4. These reactoins and the preceding isomerizations have also been studied by means of deuterium labelling. From the results it is concluded that the three fragmentation reactions most probably occur from ions with a C—C—S skeleton. Appearance energy measurements for ions generated with the two structures above and all give rise to the same ΔHf value for these three isomeric forms. Ab initio molecular orbitals calculations confirm that these three ions fortuitously have very similar heats of formation. A potential energy diagram rationalizing the isomerizations and the principal fragmentation reaction is presented.
    Additional Material: 1 Ill.
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  • 3
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of a series of N-nitrosamines for carcinogenicity studies presented an opportunity to study mass spectral fragmentation schemes in detail. Condensed spectra are listed for 146 N-nitrosamines of widely differing structures, including nitroso derivatives of commercial drugs and insecticides. Aliphatic nitrosamines were generally characterized by molecular ions and loss of OH. Subsequent fragmentation via α-cleavage is similar to that of aliphatic amines. The loss of OH is believed to result in a cyclic ion. Substituted aliphatic nitrosamines varied in fragmentation schemes with structure and position of the substituent groups. However, most showed α-cleavage at some point in fragmentation. When substituted with aromatic groups, prominent peaks due to the aromatic moiety were observed. The alicyclic nitrosamines showed losses of NO, NOH and OH and subsequent α-cleavages. Nitrosamides were characterized by rupture of the carbonyl to nitrogen bond. Spectra of substituted ureas usually showed charge retention by the carbonyl fragment, while carbamate esters showed ions from both fragments.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 444 (1978), S. 21-29 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemical Reactions in Molten Salts. XVIII. Synthesis of Methyltin Trichloride, Ch3SnCl3A process for the synthesis of CH3SnCl3 by reaction of molten SnCl2 and CH2Cl infused salts is described. Out of the systems investigated with NaCl, KCl, AlCl3, ZnCl2, KZnCl3, LiAlCl4, NaAlCl4, KAlCl4, and CuAlCl4, the systems with NaAlCl4 and NaAlCl4/KAlCl4 proved best. We measured the space-time-yield (RZA) as a function of the salts admixed to SnCl2 as well as a function of the reaction temperatur, gasification, and inlet rate of CH3Cl respectively. The optimum reaction conditions are investigated and the system SnCl2//NaAlCl4 is described.
    Notes: Ein Verfahren zur Synthese von CH3SnCl3 durch Reaktion von geschmolzenem SnCl2 mit CH3Cl in Salzschmelzen wird beschrieben. Von den untersuchten Systemen mit NaCl, KCl, AlCl3, ZnCl2, KZnCl3, LiAlCl4, NaAlCl4, KAlCl4 und CuAlCl4 erwiesen sich als besonders vorteilhaft NaAlCl4 und NaAlCl4/KAlCl4. Gemessen wurde die Abhängigkeit der Raum-Zeit-Ausbeute (RZA) vom Zusatz von Fremdsalz zum SnCl2 sowie von der Reaktions-Temperatur, der Begasung und der Einleitgeschwindigkeit von CH3Cl, und die optimalen Versuchsbedingungen bestimmt. Das System SnCl2/NaAlCl4 wird beschrieben.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 416 (1975), S. 306-310 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Substitution Reactions with Sulphur DiimidesSubstituted sulphur diimides are obtained by the reactions of (CH3)3Si—N=S=N—Si(CH3)3 with CH3SO2Cl and CCl3SCl or with P2O3F4 and (CH3)3Si—N=S=N—SN(CH3)2. S4N4 reacts with (CH3)2Si[N(CH3)2]2 to from (CH3)2Si(N(CH3)2)—N=S=N—SN(CH3)2 while S3N2Cl2 yields (CH3)2Si(Cl)—N=S=N—SN(CH3)2.It is possible to substitute the chlorine atom by diethylamine in the last compound.The new compounds are intermediates for the syntheses of cyclic sulphur-nitrogen compounds. They were characterized by mass-, ir-, 1H-nmr spectra and elemental analysis.
    Notes: Substituierte Schwefeldiimide werden durch Umsetzung von (CH3)3Si—N=S=N—Si(CH3)2 mit CH3SO2Cl und CCl3SCl oder von P2O3F4 mit (CH3)3Si—N=S=N—SN(CH3)2 dargestellt. S4N4 bzw. S3N2Cl2 reagieren mit (CH3)2Si[N(CH3)2]2 zu (CH3)2Si(N(CH3) 2)—N=S=N—SN(CH3)2 und (CH3)2Si(Cl)—N=S=N—SN(CH3)2.In der letzten Verbindung kann man das Chloratom durch Diäthylamin substituieren. Die neuen Verbindungen stellen Zwischenprodukte für die Synthese cyclischer Schwefel-Stickstoff- Verbindungen dar. Sie wurden durch Massen-, IR-, 1H-NMR-Spektren und Elementaranalysen charakterisiert.
    Additional Material: 1 Tab.
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  • 6
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    In:  Other Sources
    Publication Date: 2011-08-17
    Description: A critical analysis is given of the applicability of six-beam models to radiative transfer in particulate materials. The method of introducing transverse scattering in these models is shown to cause fundamental difficulties in the case of physically plausible phase functions; in particular, the effective absorptivity is abnormally large and thus results in incorrect reflectances and transmittances. Six-beam calculations for several media are compared with accurate solutions, with Chu-Churchill two-beam results, and with a simple modification to the Eddington approximation, the last being generally superior over a wide range of conditions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Applied Optics; 15; Dec. 197
    Format: text
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  • 7
    Publication Date: 2019-06-27
    Description: An experimental study of the initial development region of a hypersonic turbulent free mixing layer was made. Data were obtained at three stations downstream of a M = 19 nozzle over a Reynolds range of 1.3 million to 3.3 million per meter and at a total temperature of about 1670 K. In general, good agreement was obtained between electron-beam and conventional probe measurements of local mean flow parameters. Measurements of fluctuating density indicated that peak root-mean-square (rms) levels are higher in the turbulent free mixing layer than in boundary layers for Mach numbers less than 9. The intensity of rms density fluctuations in the free stream is similar in magnitude to pressure fluctuations in high Mach number flows. Spectrum analyses of the measured fluctuating density through the shear layer indicate significant fluctuation energy at the lower frequencies (0.2 to 5 kHZ) which correspond to large-scale disturbances in the high-velocity region of the shear layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TN-D-7981 , L-10138
    Format: application/pdf
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  • 8
    Publication Date: 2019-06-27
    Description: A computer code, based upon a finite element solution algorithm, was developed to solve the governing equations for three-dimensional, reacting boundary region, and constant area ducted flow fields. Effective diffusion coefficients are employed to allow analyses of turbulent, transitional or laminar flows. The code was used to investigate mixing and reacting hydrogen jets injected from multiple orifices, transverse and parallel to a supersonic air stream. Computational results provide a three-dimensional description of velocity, temperature, and species-concentration fields downstream of injection. Experimental data for eight cases covering different injection conditions and geometries were modeled using mixing length theory (MLT). These results were used as a baseline for examining the relative merits of other mixing models. Calculations were made using a two-equation turbulence model (k+d) and comparisons were made between experiment and mixing length theory predictions. The k+d model shows only a slight improvement in predictive capability over MLT. Results of an examination of the effect of tensorial transport coefficients on mass and momentum field distribution are also presented. Solutions demonstrating the ability of the code to model ducted flows and parallel strut injection are presented and discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-2661
    Format: application/pdf
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  • 9
    Publication Date: 2019-06-27
    Description: Results are presented for unsteady laminar thermal convection in compressible fluids at various reduced levels of gravity in a rectangular enclosure which is heated on one side and cooled on the opposite side. The results were obtained by solving numerically the equations of conservation for a viscous, compressible, heat-conducting, ideal gas in the presence of a gravitational body force. The formulation differs from the Boussinesq simplification in that the effects of variable density are completely retained. A conservative, explicit, time-dependent, finite-difference technique was used and good agreement was found for the limited cases where direct comparison with previous investigations was possible. The solutions show that the thermally induced motion is acoustic in nature at low levels of gravity and that the unsteady-state rate of heat transfer is thereby greatly enhanced relative to pure conduction. The nonlinear variable density profile skews the streamlines towards the cooler walls but is shown to have little effect on the steady-state isotherms.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 70; Aug. 26
    Format: text
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  • 10
    Publication Date: 2019-06-27
    Description: A three dimensional finite element computer code was developed to analyze ejector and axisymmetric fluted mixer systems whose flow fields are not significantly influenced by streamwise diffusion effects. A two equation turbulence model was used to make comparisons between theory and data for various flow fields which are components of the ejector system, i.e., (1) turbulent boundary layer in a duct; (2) rectangular nozzle (free jet); (3) axisymmetric nozzle (free jet); (4) hypermixing nozzle (free jet); and (5) plane wall jet. Likewise, comparisons of the code with analytical results and/or other numerical solutions were made for components of the axisymmetric fluted mixer system. These included: (1) developing pipe flow; (2) developing flow in an annular pipe; (3) developing flow in an axisymmetric pipe with conical center body and no fluting and (4) developing fluted pipe flow. Finally, two demonstration cases are presented which show the code's ability to analyze both the ejector and axisymmetric fluted mixers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-159467
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