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Abstract  

A sensitive method of carbon determination in silicon by activation with deuterons and3He particles followed by chemical separation of the measured nuclides13N and11C has been developed. Aside from the etch removal after irradiation, it is essential for a low detection limit to avoid too much thermal exposure of the target surface during the irradiation process, or else microflaw formation and diffusion on the surface have to be anticipated. The ion current must have an optimal rather than a maximum value.

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It is suggested to carry out thermogravimetric measurements at pressures between 1 and 100 torr. In this pressure range thermal gas flow will cause only small disturbances, and the gas evolution will be much less inhibited by the surrounding gas than at higher pressures. In a thermal analysis of calcium oxalate, carried out with an apparatus containing a pressure controller, the weighing disturbances were reduced to a few micrograms.

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Abstract  

An accurate knowledge of the ratio Ca/P in bone biopsies is very useful in the diagnosis of osteoporosis. Similarly, measurements on muscle biopsies are important in understanding the disturbance of intracellular fluid and electrolyte (Na, Cl, K and P) balance in patients with metabolic myopathies (muscle diseases) and acid-base disturbances including renal failure. The ratio Ca/P in normal subjects was found to be 2.30. Similarly, the ratio K/P was found to be very nearly constant in normal subjects.

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pv. syringae and P. fluorescence caused disturbances of energy flow in PSII by lowering its efficiency ( Table 1 ). In comparison with absolute control values of parameters F v / F m and phenomenological fluxes (energy absorption ABS, energy

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Abstract  

In machine drawn weldor safety glasses with a different protection grade and a total iron oxide content of 6.8–9.5% the lattice coordination of iron and the Fe2+/Fetot ratio were determined by Mössbauer spectroscopy. In combination with electron beam microanalysis and specific sample preparation, homogeneity disturbances were observed inside the defect glass as well as on its surface.

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Abstract  

In the course of ion-exchange separations of highly active solutions, the radiolysis gives rise to considerable disturbances and deteriorated separation results. On the example of241Am/242Cm separations some results of radiolysis investigations for Dowex 50X8 are briefly shown, and experiences with the choice of parameters of a high-pressure column system are described for several examples.

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The stability behaviour of a thin-film superconductor under a localized release of thermal disturbance is investigated. Two-dimensional conjugate film/substrate conduction equation with anisotropic thermal conductivity of the film, and Joule heat are employed to investigate effects of substrate and thermal properties on the intrinsic stability and quenching recovery. To consider the thermal boundary resistance between film and substrate, an interfacial-layer model (ILM) with very low diffusivity and an acoustic mismatch model (AMM) are employed. Results show that the thermal boundary resistance influences strongly the intrinsic stability. Thermal boundary resistance increases intrinsic stability if the thermal conductivity of the substrate or the disturbance energy is large. Higher Biot numbers and thermal conductivity ratios of film to substrate in longitudinal direction influence stability favorably. We demonstrate also that operation of a film/substrate system, such as YBCO/MgO, is either intrinsically stable or irrecoverably unstable.

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Abstract  

The mass spectrum of secondary ions emitted from a solid surface under ion bombardment is characteristic of the composition of the superficial monolayers. By the use of very low primary ion current densities and highly sensitive detection techniques, analysis can be performed without measurable disturbance of the original first monolayers. Some results demonstrating the capabilities of this ‘static’ method of secondary ion mass spectrometry (SIMS) are presented.

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Abstract  

Instrumental neutron activation techniques for the determination of 26–36 impurities in MoSi2, WSi2, TiB2, NbB2, TiC, NbC and SiC with detection limit of 0.1–0.000001 ppm in the range of contents of 100–0.001 ppm have been developed. The determination of this large number of elements was achieved with using complex conditions of irradiation, including varying neutron energy and choosing optimal time parameters. The contents of short-lived radionuclides also have been determined. Self-shielding and disturbance of neutron flux, absorption of -rays were taken into account both with the help of literature data and preliminarily obtained experimental results.

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Abstract  

Aqueous Pb(II) samples, spiked with210Pb/210Bi in secular equilibrium to study container adsorption, can provide some helpful insights if one takes advantage of the Cherenkov effect. While both radionuclides give high efficiencies when counted in a scintillator cocktail medium, only210Bi has a sufficiently energetic -particle to yield an appreciable count rate in a water medium. Thus, monitoring the cocktail-to-water count rate ratio can provide important clues as to what happens during adsorption. A significant change in the ratio indicates not only disturbance of the secular equilibrium relationship, but indicates which nuclide is preferentially adsorbed.

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