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191.
The development of diffusion creep (DC) accompanying superplastic deformation (SPD) of the highly doped nickel alloy ZhS6KP is studied based on an investigation of the redistribution of dispersed intragrain deposits of the phase of Ni3(Al, Ti). Deposit-free zones (DFZ) are formed in the alloy, held at the temperature of SPD and accompanying deformation at the grain boundaries. The contribution of DC to the deformation was determined from a comparative analysis of the width of the DFZ in the deformed and undeformed parts of the samples for different grain sizes and rates of DC taking into account diffusion accommodation. It was established that for the optimum rate of SPD the upper limit of the contribution of DC to deformation for 2-m grains does not exceed 11%. It is concluded, based on the distribution of DFZ, that the effect of DC accompanying SPD is determined by diffusion fluxes, associated with the local concentration of stress accompanying the development of grain-boundary slipping.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 40–45, June, 1986.In conclusion, we thank Yu. M. Mishin for a useful discussion of the results. 相似文献
192.
P. Herzog U. Dämmrich K. Freitag C. -D. Herrmann K. Schlösser 《Zeitschrift für Physik B Condensed Matter》1986,64(3):353-356
Nuclear magnetic resonance of82Br oriented at low temperature in iron has been observed with a sample prepared by ion implantation atT<0.2 K. The asymmetric resonance signal can be decomposed in a broad background signal and a narrow line of FWHM=1.8 (4) MHz which can be attributed to82Br in undisturbed substitutional sites of Fe. From the center frequency of this narrow line (B
ext=0)=201.86(13) MHz we derive the magnetic hyperfine field asB
hf(BrFe)=81.38(6) T. This value is considerably larger than the result of theoretical calculations. 相似文献
193.
Optical frequency doubling of a single-mode cw Rhodamin 6G ring dye laser is performed with a thin angle-tuned LiIO3 Brewster cut crystal in a stabilized passive ring resonator. A conversion efficiency of =5 mW uv/320 mW fundamental input power was achieved at =603 nm. 相似文献
194.
F. A. Gianturco F. Ragnetti M. Faubel B. Martínez-Haya L. Y. Rusin F. Sondermann U. Tappe 《Chemical physics》1995,200(3):405-413
A recently proposed anisotropic potential model for the interaction of a fluorine atom with a hydrogen molecule treated as a rigid rotor analysed by carrying out exact quantum calculations of elastic and rotationally inelastic differential cross sections for comparison with previoully reported F---H2 and newly measured F---D2 state selected measurements. The sensitivity of the cross sections to changes of the potential anisotropy and to isotopic substitution is examined. The results provide specific indications on the features of the best potential energy surface in terms of its average ‘size’ and its most likely anisotropy responsible for inelastic rotational excitations occuring at collision energies of about 85 meV. 相似文献
195.
The reaction of C5H5Rh(CO)(PiPr3) (1] which is prepared from C5H5Rh(CO)2 and neat P1Pr3, with the nitriloxides 2-RC6H4CNO (R = H, Cl) leads to the formation of the metallaheterocycles C5H5(P1Pr3)
) (2, 3) in 90–95% yield. Compound 1 reacts with tosylazide to give the C,N-bound isocyanate complex C5 H5(PiPr3)Rh(η2-TosN=C=O) (6). Analogously, on treatment of C5Me5Co(CO)(PMe3) with phenylazide the phenylisocyanate derivative C5Me5(PMe3)Co(η2-PhN=C=O) (7) is formed. Protonation of 7 with CF3CO 2H affords the non-ionic carbamoylcobalt complex C5Me5(PMe3)Co[C(O)NHPh](O2CCF3) (8). The X-ray structural analysis of 2 reveals the presence of an almost planar
heterocycle in which the two Rh-C distances differ by 0.045 Å 相似文献
196.
Zusammenfassung Für Elementbestimmungen in Abwasser wird ein Röntgenfluorescenzverfahren beschrieben. Zur Probenvorbereitung werden die Elemente durch Gefriertrocknung auf einem inerten Träger angereichert. Diese Anreicherung ist nicht selektiv und erfaßt praktisch alle in Abwasser gelösten und suspendierten Verunreinigungen. Für die Berechnung der Elementkonzentrationen aus den gemessenen Fluorescenzintensitäten wird ein Matrixkorrekturverfahren angegeben, welches dem unterschiedlichen Absorptionsverhalten der Probenmatrix Rechnung trägt. Die Massenabsorptionskoeffizienten werden durch Messung der diffus gestreuten Bremsstrahlung bzw. der Comptonstreustrahlung ermittelt. Die Selbstabsorption des zu bestimmenden Elementes wird rechnerisch berücksichtigt. Das Korrekturverfahren kann auf alle mit Röntgenfluorescenzanalyse bestimmbaren Elemente angewendet werden.
Determination of elements in waste water by x-ray fluorescence analysis: Sample preparation and matrix correction method
Summary For sample preparation the elements are enriched upon an inert carrier by freeze-drying. This enriching procedure is not selective and collects all dissolved and suspended contaminations from the waste water. In order to calculate the element concentrations from the measured fluorescence intensities a matrix correction method is given which considers the different absorption behaviour of the matrix. The mass absorption coefficients are obtained by measuring the scattered X-ray tube spectrum or a Compton scattered X-ray tube line, respectively. The self-absorption of the element to be determined is taken into account. The correction method is applicable to all elements detectable by X-ray fluorescence.
Herrn Dr. H. Wagner danken wir für das stete Interesse, die zahlreichen konstruktiven Diskussionen und die Hilfe beim Abfassen des Manuskripts. 相似文献
197.
Charles U. Pittman Thane D. Rounsefell 《Journal of polymer science. Part A, Polymer chemistry》1973,11(3):621-628
Three programs have been written for calculations involving use of the penultimate copolymerization model. The first computes the penultimate reactivity ratios from composition-conversion data, without constraints, at any conversion. A nonlinear leastsquares technique using Marquardt's algorithm is employed. The second program computes the four optimum starting monomer feed ratios, M10/M20 which should be used by the experimenter from the penultimate reactivity ratios. These optimum feed ratios are obtained by choosing the conditions necessary to minimize the determinant of the variance-covariance matrix. The input for the first program includes estimates of known values of the penultimate reactivity ratios. By using these two programs sequentially the experimenter has an optimized experimental approach toward evaluating penultimate reactivity ratios at any conversion. Finally, a program has been provided to calculate composition–conversion data, given penultimate reactivity ratios. 相似文献
198.
L Bedard M J Young D Hall T Paul K U Ingold 《Journal of the American Chemical Society》2001,123(50):12439-12448
Rates of peroxidation of human LDL and rates of consumption of the LDL's alpha-tocopherol (TocH) have been measured at 37 degrees C. Peroxidation was initiated by radicals generated in the aerated aqueous phase at known rates by thermal decomposition of appropriate precursors: superoxide (O2(*-)/HOO(*)) from a hyponitrite and alkylperoxyls (ROO(*), two positively charged, one negatively charged and one neutral) from azo compounds. The efficiencies of escape from the solvent cage of the geminate pair of neutral carbon-centered radicals was found to be 0.1, but it was 0.5 for the three charged radicals, a result attributed to radical/radical Coulombic repulsion within the cage. All four alkylperoxyls initiated and terminated tocopherol-mediated peroxidation (TMP) with about equal efficiency and essentially all of these radicals that were generated were consumed in these two reactions. TMP is a radical chain process, and when initiated by the alkylperoxyls, the rate of LDL peroxidation was faster in the early stages while TocH was present than later, after all of this "antioxidant" had been consumed. In contrast, only about 3-4% of the generated superoxide radicals reacted in any measurable fashion with TocH-containing LDL at pH's from 7.6 to 6.5 and peroxidation was much slower than with a similar rate of generation of alkylperoxyls. After all the TocH had been consumed, LDL peroxidation was negligible at pH 7.6 and 7.4, but at pH 6.8 and 6.5, the peroxidation rates showed a large increase over the rates while the TocH had been present. That is, endogenous TocH behaves as an antioxidant in LDL subjected to attack by the physiologically relevant superoxide radical, whereas TocH behaves as a prooxidant in LDL subjected to attack by the probably far less physiologically important alkylperoxyls. Rates of LDL peroxidation initiated by superoxide increased as the pH was decreased, and the results are consistent with the initiation of peroxidation of fresh LDL occurring via H-atom abstraction from TocH by HOO(*) to form the Toc(*) radical and termination by reaction of O2(*-) with Toc(*), a process that occurs partly by addition leading to TocH consumption and partly by electron plus proton transfer leading to the regeneration of TocH. 相似文献
199.
Infrared photodissociation spectra of (CH3OH) n clusters (n=2, 3 and 6) and the mixed dimer C2H4 · CH3COCH3 are presented. The clusters are generated in a supersonic jet expansion and size selected by scattering from a helium atomic beam combined with mass spectrometric detection. Continuous CO2-lasers are used to vibrationally excite the molecules in the cluster leading to rapid dissociation of the complex. Various dissociation peaks that are found in single-laser dissociation spectra can be assigned unambigously in a pump-probe experiment with two lasers to either different isomers (acetone-ethene dimer) or splitted lines of one isomer (methanol hexamer). For size distributions, the method is able to select contributions of single masses which is demonstrated for mixtures of methanol dimers and trimers. 相似文献
200.
I. W. Schulz U. Illgen J. Scheve K. -D. Backhaus 《Journal of Thermal Analysis and Calorimetry》1988,33(3):699-705
For application in catalysis and adsorption processes, zeolites are synthesized on the surface of spray-dried kaolin microspheres. Various thermal effects are used for the rapid characterization of the zeolite type and content. From DTA measurements, the exothermic lattice break-down peak gives information on the zeolite type and the thermal stability of the sample. Measurements of the heats of immersion by a very simple and quick method allow conclusions about the type and the sorption properties of the zeolite part of the clay. The most precise method to estimate the zeolite content was a standardized technique of desorption and readsorption of water or organic compounds by means of a thermobalance.
Zusammenfassung Zur Anwendung in der Katalyse und bei Adsorptinsprozessen werden Zeolithe auf der Oberfläche sprüh-getrockneter Kaolin-Mikrokugeln eingesetzt. Verschiedene thermische Effekte werden zur schnellen Charakterisierung des Zeolith-Typs und -Gehalts genutzt. Der exotherme DTA-peak beim Gitterzusammenbruch liefert Informationen über Zeolith-Typ und thermische Stabilität der Probe. Eine sehr einfache Schnellmethode zur Messung der Immersionswärmen erlaubt Schlussfolgerungen über Typ und Sorptionseigenschaften des zeolithischen Anteils des Tons. Die genaueste Methode zur Bewertung des Zeolithgehalts war eine standardisierte thermogravimetrische Desorptions- und Readsorptions-Methode mit Wasser oder organiscen Verbindungen.
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