[en] The method described by the authors is based on the knowledge that there is an excellent correlation obtainable in accordance with an exponential function between the serum activity curve and the camera activity curve (ROI over the thorax). One or two blood samples will suffice to correct the camera activity curve and thus to adjust the time-dependent curve of the activity concentration in the blood serum. The method A described in this paper requires one blood sample taken after 12 min p.i.; for method B, two blood samples are taken at 2 and 20 min. p.i.. The times of sample taking are based on experience, allowing best possible corrections. The effective renal plasma flow is determined using the two-compartment model. For validation of the methods, the results have been compared with the slope-clearance technique (method C, 5 blood samples taken at 2, 6, 12, 20, 28 min. p.i.). The clearance data obtained by methods A, B, and C have then been compared with the data determined with the gamma camera applying a technique comparable with the 'Oberhausen' method. Patients have been injected with 123-I-Hippuran, images taken on the patient in lying position, the camera focussing on kidneys and part of the thorax. The measured data are stored by a small computer, and the evaluating program also allows calculation of the lateral parts' contribution to the entire function, of the maxima and the half-lives of activity curves over the kidneys. (orig./MG)

[en] The oxidation process of the surface of superconductors is usually employed in the fabrication of Josephson tunnel junctions. The purpose of this paper is to clarify whether the oxidation model for the surface of Nb₃Ge is equally applicable to other A15 superconductors. The oxidation mechanisms were found to be divided into three groups according to ionization energies (I /SUB p/ ) of constituent atoms. In the A15 group of superconductors (formula A₃B), case I; I /SUP A/ /SUB p/ I /SUP B/ /SUB p/ : A atoms are preferentially ionized and diffuse to the surface and then form oxides. On the other hand, B atoms are hardly or little oxidized, These cases are Nb₃Ge and V₃Si, and their native oxide layers are not proper for a tunnel barrier. An exception case is Nb₃Si, but the reason is not clear. Case II; I /SUP A/ /SUB p/ I /SUP B/ /SUB p/ : Both A and B atoms are almost equally oxidized and form a composite oxide of A and B. The case is Nb₃Sn. Case III; I /SUP A/ /SUB p/ I /SUP B/ /SUB p/ : B atoms are preferentially oxidized at first and A atoms are slowly oxidized later. This case is Nb₃Al. The native oxide is proper for a tunnel barrier

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[en] A new method of nitrogen doping into GaAssub(1-x)Psub(x) was attempted using the ionized beam in molecular beam epitaxy (MBE). With the ionization system attached to MBE system, the ionized nitrogen beam was supplied onto the substrate during MBE. Nitrogen doping of more than 10¹⁸cm^-3 was successfully made without distrubing the high crystallographic quality of the epitaxial layer. Photoluminescence measurements show that the nitrogen atoms introduced into the epitaxial layer act as isoelectronic luminescence centers. The effective sticking coefficient of ionized nitrogen for GaAssub(1-x)Psub(x) at 580⁰C is estimated as the order of 0.01. (Auth.)

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[en] This paper presents characterization of amorphous boron (a-B) films prepared by the electron cyclotron resonance plasma chemical vapor deposition method using diborane (B₂H₆) and hydrogen mixtures. Compositional analyses show that hydrogen is the only impurity which influences film properties appreciably. The infrared absorption study shows that the hydrogen is incorporated into the film in the terminal bonding form. The hydrogen concentration has been estimated using the semiempirical equation given by Blum, Feldman, and Satkiewicz [Phys. Status Solidi A 41, 481 (1977)], which can be verified by the more fundamental principle. The infrared absorption study also shows that the amorphous films possess some short-range order related with the icosahedral structure. These observations allow us to consider that this film belongs to one of alloyed materials and is true hydrogenated a-B. In order to study the contributions of hydrogen to the film properties, variations of the color and the electrical resistivity of the film have been examined with changing the substrate temperature and the B₂H₆ concentration in source gases. These variations can be described with consistency in terms of the optical absorption edge. The films are a-B:H at substrate temperatures below 350 degree C. The hydrogen incorporation results in increase in the resistivity and increase in the optical transparency. At substrate temperatures above 350 degree C, the hydrogen is evolved from the film regardless of the B₂H₆ concentration, and intrinsic a-B films are obtained

[en] Two-dimensional epitaxial growth of SrCuO_2-y and SrTiO_3-z was examined using ArF pulsed laser MBE for the fabrication of cuprate-based superlattices. Throughout the film growth, streaky RHEED patterns were observed and their intensities oscillated with the same periodicities as the lattice spacings of SrCuO₂ and SrTiO₃; tetragonal SrCuO_2-y containing infinite (CuO₂)^2- layers and SrTiO_3-z were grown epitaxially on SrTiO₃(001). The laser MBE deposition of epitaxial SrCuO_2-y and SrTiO_3-z films was iterated to prepare cuprate-based superlattices. (orig.)

[en] An oxide layer grown on the A15 Nb³Ge surface after exposing to pure oxygen is found to be mainly Nb²O⁵ from the in situ observation of x-ray photoelectron spectroscopy. The thickness of the Nb²O⁵ layer varies with the oxidation time by following the logarithmic-growth-law. The oxide layer serves as a protective stable film with a thickness of around 1.5 nm. Beneath the oxide layer a Nb-deficient layer occurs in a thickness of 2 nm due to the preferential diffusion of Nb atoms. This is caused by the contact potential difference between Nb³Ge and adsorbed oxygen layer and the ionization potential difference between Nb and Ge atoms

[en] A variety of effects of substrate bias upon an electron cyclotron resonance plasma deposition have been studied, taking the deposition of amorphous boron carbide films as an example. First, the impact energy of ions incident on substrates was studied through the variation of the sheath potentials formed on insulating and conducting substrates. For this purpose, the plasma potential (V_p) was measured by the bias current-voltage (I_b-V_b) analysis, and the floating potential (V_f) was measured by the Langmuir probe method. These analyses show that the plasma potential is sufficiently influenced by the substrate bias for positive biases even if the area of the bias electrode is small. The energy of ions incident on conducting substrates is not effectively changed by imposing a positive bias. This effect can be explained in terms of the global balance of the electron and ion currents. This consideration leads to the criterion for the area of bias electrode at which the substrate bias perturbs the plasma potential. Next, the effects of the substrate bias upon the deposition processes and properties of the deposited films were studied through the variations of the deposition rates and the infrared absorption due to the atomic vibrations in the films. The deposition rates vary with the substrate bias according to the variation of sheath potentials: V_p-V_f for insulating substrates and V_p-V_b for conducting substrates. As the substrate bias increases negatively, the deposition rate on conducting substrates increases. This increase is hardly explained by the direct contribution of ions to the deposition