Spectrographic Determination of Microamount of Calcium in Magnesium with the Transient Discharge Source Unit

A spectrographic method was studied to determine microamount of calcium in magnesium metal and magnesium alloys, and it was found that calcium in magnesium could be determined by exciting sample solution in a porous-cup electrode with the transient discharge source unit. The results obtained were as follows : (1) In consideration of the viscosity of magnesium solution and the spectral intensity of calcium, 0.5g of sample was dissolved in hydrochloric acid, afterwards diluted to 50 ml. (2) The discharge conditions were E (discharge voltage)=200V, C=18μF, L=30μH, and R=2Ω (3) Exposure was started after 15-sec preliminary discharge, as the discharge was unstable in the biginning of its start. (4) Aluminium, zinc, manganese, iron and zirconium contained in magnesium alloys had no influence on the analytical results of calcium determination, excepting the case when sample contained about 5 per cent of zinc. (5) Samples containing 0.01 to 0.3 per cent of calcium were analysed with Sr II 4215.52A/Ca II 3933.67A as the analytical line pair, the reproducibility being 5 to 7 per cent. (6) It was ascertained that the lower limit of the determination of calcium could be extended down to about 0.001 per cent by using magnesium of higher purity as the base material

Spectrographic Determination of Microamounts of Arsenic, Antimony, Bismuth, Tin and Lead

After calcium nitrate (used as the spectroscopic buffer) and cadmium nitrate (used as the internal standard) were added to the sample solution, the mixed solution was evaporated and a part of the nitrate salt deposited was excited in the cavity of graphite electrode by direct current are method with a medium quartz spectrograph. By this salt powder method, at least 3γ of arsenic, 1γ of antimony, 0.3γ of tin and lead, and 0.1γ of bismuth could be determined spectrographically

Spectrographic Determination of Microamounts of Calcium and Magnesium in Cast Iron by Porous-Cup Technique

A spectrochemical method was studied to determine simultaneously microamounts of calcium and magnesium in cast iron. Samples were dissolved with acid, iron was removed by methyl isobutyl ketone extraction, then the solution containing calcium and magnesium was put in a porous-cup electrode and the spectra were excited with a condensed spark. Strontium and beryllium were added as the internal standard elements for calcium and magnesium, respectively, and SrII 4215.52A/CaII 3933.67A and BeII 3130.42A/MgII 2802.70A were used as the analytical line pairs. This method was applicable to the determination of calcium and magnesium in contents above 0.005 per cent, and the variation coefficients were 13.5 per cent for calcium and 9.7 per cent for magnesium at a concentration level of 0.01 per cent

Spectrographic Determination of Ferroalloys. I : Spectrographic Determination of Microamounts of Arsenic and Antimony in Ferromanganese

A rapid and accurate method was examined with a quartz spectrograph of medium type to determine arsenic and antimony contained in ferromanganese as impurities. Stable excitation conditions were studied for both block sample and powdered sample, and it was found optimal to excite a mixture of powdered sample and graphite powder by direct current intermittent arc. Silver was introduced into the mixture as the internal standard, and Ag 2309.64A/AsI 2288.12A and Ag 2309.64A/SbI 2311.47A were used as analytical line pairs. By this method arsenic and antimony in ferromanganese were determined with variation coefficients of 5 to 11 per cent and about 6 per cent, respectively

The effect of varying sound velocity on primordial curvature perturbations

We study the effects of sudden change in the sound velocity on primordial curvature perturbation spectrum in inflationary cosmology, assuming that the background evolution satisfies the slow-roll condition throughout. It is found that the power spectrum acquires oscillating features which are determined by the ratio of the sound speed before and after the transition and the wavenumeber which crosses the sound horizon at the transition, and their analytic expression is given. In some values of those parameters, the oscillating primordial power spectrum can better fit the observed Cosmic Microwave Background temperature anisotropy power spectrum than the simple power-law power spectrum, although introduction of such a new degree of freedom is not justified in the context of Akaike's Information Criterion.Comment: 12 pages, 3 figures; references added; appendix modifie

Specific-heat study for ferromagnetic and antiferromagnetic phases in SrRu_{1-x}Mn_xO3

Low-temperature electronic states in SrRu_{1-x}Mn_xO_3 for x <= 0.6 have been investigated by means of specific-heat C_p measurements. We have found that a jump anomaly observed in C_p at the ferromagnetic (FM) transition temperature for SrRuO_3 changes into a broad peak by only 5% substitution of Mn for Ru. With further doping Mn, the low-temperature electronic specific-heat coefficient gamma is markedly reduced from the value at x=0 (33 mJ/K^2 mol), in connection with the suppression of the FM phase as well as the enhancement of the resistivity. For x >= 0.4, gamma approaches to ~ 5 mJ/K^2 mol or less, where the antiferromagnetic order with an insulating feature in resistivity is generated. We suggest from these results that both disorder and reconstruction of the electronic states induced by doping Mn are coupled with the magnetic ground states and transport properties.Comment: 4 pages, 2 figures, submitted to the proceedings of ICM2009 (Karlsruhe

Angular dependence of Josephson currents in unconventional superconducting junctions

Josephson effect in junctions between unconventional superconductors is studied theoretically within the model describing the effects of interface roughness. The particularly important issue of applicability of the frequently used Sigrist-Rice formula for Josephson current in d-wave superconductor / insulator / d-wave superconductor junctions is addressed. We show that although the SR formula is not applicable in the ballistic case, it works well for rough interfaces when the diffusive normal metal regions exist between the d-wave superconductor and the insulator. It is shown that the SR approach only takes into account the component of the d-wave pair potential symmetric with respect to an inversion around the plane perpendicular to the interface. Similar formula can be derived for general unconventional superconductors with arbitrary angular momentum l.Comment: 4 pages, 4 figure

Nonmonotonic temperature dependence of critical current in diffusive d-wave junctions

We study the Josephson effect in D/I/DN/I/D junctions, where I, DN and D denote an insulator, a diffusive normal metal and a d-wave superconductor, respectively.The Josephson current is calculated based on the quasiclassical Green's function theory with a general boundary condition for unconventional superconducting junctions. In contrast to s-wave junctions, the product of the Josephson current and the normal state resistance is enhanced by making the interface barriers stronger. The Josephson current has a nonmonotonic temperature dependence due to the competition between the proximity effect and the midgap Andreev resonant states.Comment: 5 pages, 4 figure