Simultaneous determination of orthophosphate and total phosphates (inorganic phosphates plus purine nucleotides) using a bioamperometric flow-injection system made up by a 16-way switching valve

Orthophosphate and total phosphates (inorganic phosphates plus purine nucleotides) can be determined simultaneously in a novel flow-injection system made up by a 16-way switching valve with two sample loops, acid phosphatase (AcP) immobilized reactor and a delay coil needed to separate two peaks corresponding to two sample portions injected simultaneously. An orthophosphate enzyme electrode with a hybrid membrane of trienzyme film and poly(1,2-diaminobenzene) film was used to selectively detect both the endogenous orthophosphate and orthophosphate generated enzymatically into the AcP immobilized reactor, without any interferences from electroactive species, such as ascorbate and urate. Because two sample portions passed through the flow line with different residence time, two peaks were obtained. The first peak corresponded selectively to orthophosphate and the second peak to the total of inorganic phosphates and purine nucleotides. The maximum currents of both peaks were linearly related to the concentration of orthophosphate and total phosphates (as orthophosphate) in the range 5×10⁻⁷-8×10⁻⁴ M, respectively; 30 samples per hour can be processed with an R.S.D. <2.5%.     

Analysis of the peptides (Prp106-126, MSI-78A,and Oxaldie 1) with the same biological activity by discrete Fourier transform: toward a selection rule in ligand-receptor interaction

Here, we first report a novel method in which the "desired cross-spectrum" of the peptides Prp106-126, MSI-78A, and oxaldie 1 with the same biological activities is obtained by the multiplication of two cross-spectra derived from the RNA sequence and from the cognate amino acid sequence by discrete Fourier transform (DFT), respectively. Based on a well-known method reported previously, we investigated the cross-spectrum by the multiplication of two of three desired cross-spectra. As a result, we found that one prominent peak occurring in the three cross-spectra showed the same frequency when a binary scale was used as a parameter of nucleotide or amino acid in the analysis. Moreover, we examined the relationship between a binary scale and other physicochemical ones. Almost the same results could be reproduced when the absolute electronegativity scale (or the absolute hardness one) was used, but not in the case of the hydrophobic or electron-ion interacting potential scale reported previously. This indicates that either the absolute electronegativity scale (or the absolute hardness one) or a binary scale, or both is very useful in extracting the information desired for various proteins by the present method from the amino acid and the RNA sequence.     

Giant magnetorefractive effect in magnetic granular CoFe-MgF alloys

This paper reports on an IR study (5–20 µm) of the dispersion and field dependences of the magnetorefractive effect in granular CoFe-MgF (metal-insulator) systems, which exhibit, in compositions close to the percolation threshold, a tunneling magnetoresistance of 7.5% in a field of 1700 Oe. The change in the reflectivity of p-polarized light under magnetization in the IR spectral region 5–7 µm is of the order of 0.1%, while in the 10-to 12-µm region, this change, reaches record-high values of 1.2–1.5%, which exceed the usual odd and even magnetooptic reflectivities in the IR range by two orders of magnitude. The magnetorefractive effect in magnetic systems with tunneling conduction originates from spin-dependent high-frequency tunneling.     

Preparation of ferromagnetic semiconducting HgCr2Se4 thin films by molecular-beam deposition

Summary Polycrystalline thin films of the ferromagnetic semiconductor HgCr₂Se₄ have been prepared for the first time on insulating MgAl₂O₄ single-crystal substrates by molecular-beam deposition and subsequent annealing with HgSe. The optimum conditions for preparing single-phase thin films of HgCr₂Se₄ were obtained. The magnetoresistance and Hall effects of these films were measured from 77 to 295 K in magnetic fields up to 1.19·10⁶ A/m. It becomes evident that these electrical properties of the films are affected by the interdiffusion layers in the films near the substrates or the magnetically disordered layers such as amorphous or grain boundaries in the films. Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16, 1982.     

Analysis of Photo-Induced Waveguide in Lithium Niobate Crystal

In this letter, we estimate the refractive index distribution in a photo-induced waveguide. The photo-induced waveguide was fabricated by scanning a focused laser beam through a lithium niobate crystal. We made use of a parametric model of refractive index distribution of the photo-induced waveguide. The results of numerical simulation on the near-field patterns of curved waveguides are compared with experimental results.     

Correlation between magnetic anisotropy induced by stress annealing and viscoelastic properties for a metallic glass ribbon

In some metallic glass ribbons, the magnetic anisotropy obtained by stress annealing, appears to be separable into two contributions, one originating from an anelastic and another from a plastic deformation of the material. These contributions are of opposite signs. Measurements of the viscoelastic parameters and the induced anisotropy obtained at identical conditions suggest a simple proportionality between the anelastic deformation and the magnetic anisotropy of anelastic origin. For the plastic contribution the connection seems more complicated.     

The magnetic phase transition of an amorphous FePC and its alloys containing Ni and Cr

The magnetic phase transition of the amorphous ferromagnetic alloys Fe₈₀P₁₃C₇, Fe₇₀Cr₁₀P₁₃C₇ and Fe₇₀Ni₁₀P₁₃C₇ has been investigated by magnetization and specific heat measurements. From the field dependence of the isothermal magnetization, the critical exponents and the Curie temperature (T_C) of Fe₈₀P₁₃C₇ were obtained to be β = 0.38 ± 0.02, γ = 1.30 ± 0.05, θ = 4.47 ± 0.05 and T_c = 586.55 ± 0.1°K. These exponents sufficiently satisfy the static scaling law. The specific heat of Fe₈₀P₁₃C₇ showed an approximate logarithmic singularity at T_c. The specific heat from Fe₇₀Ni₁₀P₁₃C₇ shows fairly broad peak and the peak almost smears out for Fe₇₀Cr₁₀P₁₃C₇.