Absorption-free calibration on X-ray fluorescence analysis of high-speed steel with glass bead preparation

This article describes a novel idea on preparation of a glass bead for X-ray fluorescence spectrometry, to determine alloyed elements in high-speed steel without any matrix correction. The quantification method using the glass bead is generally effective to reduce secondary X-ray absorption and enhancement (matrix effect) by coexisting elements in a sample. Although the glass bead is normally prepared based on a flux-to-sample ratio, the suggested method mainly controls an absolute amount of the sample in the glass bead to prevent from any interference with the matrix elements. As a result, the alloyed elements, except tungsten, in high-speed steels could be determined with high precision and accuracy, independent of the flux-to-sample ratio. However, the fluorescent X-ray intensity of tungsten Lα line (8.40 keV) was obviously influenced by the sample amount (iron content) in a glass bead; in this case, the Mα line (1.77 keV) could be employed alternatively.     

Large area lateral overgrowth of mismatched InGaP on GaAs(111)B substrates

Application of InGaAs/InGaP double‐heterostructure (DH) lasers increases the band offset between the cladding layer and the active layer more than the use of conventional 1.3 µm InGaAsP/InP lasers. As a first step in realizing 1.3 µm InGaP/InGaAs/InGaP DH lasers, we proposed InGaP lattice‐mismatched epitaxial lateral overgrowth (ELO) technique and successfully carried out the InGaP growth on both GaAs (100), (111)B and InP (100) substrates by liquid phase epitaxy. In this work, we grew the InGaP crystal on GaAs (111)B substrate by adjusting Ga and P composition in In solution, to obtain In_0.79Ga_0.21P (λ = 820 nm) virtual substrate for 1.3 µm InGaAs/InGaP DH lasers. To grow the InGaP all over the lateral surface of the substrate, the growth time was extended to 6 hours. The amount of InGaP lateral growth up to 2 hours was gradually increased, but the lateral growth was saturated. The InGaP lateral width was about 250 µm at the growth time of 6 hours. We report the result that optical microscope observation, CL and X‐ray rocking curve measurements and reciprocal lattice space mapping were carried out to evaluate the crystal quality of the grown InGaP layers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Interaction between charged soft microcapsules and red blood cells: effects of PEGylation of microcapsule membranes upon their surface properties

Four types of hydrophilic gel microcapsules containing water have been prepared by an interfacial polymerization method. Each type of microcapsules has a membrane of different composition. Using three kinds of monomers, N,N-dimethylacrylamide (DMAAm), 4-(aminomethyl)styrene (AmSt), and N,N-dimethylaminopropylacrylamide (DMAPAA), one type of aqueous copolymer having primary and tertiary amino groups was obtained. By the polymerization of three kinds of monomers, DMAAm, AmSt, and 2-[(methacryloyloxy)ethyl] trimethylammoniumchloride (METAC), another type of aqueous copolymer having primary and quaternary ammonium groups was also obtained. Two more types of copolymers were synthesized by copolymerization of -acryloxy-ω-methoxy-poly(ethylene glycol) (a-PEG) with the above two kinds of monomer mixture. These copolymers were polymerized with terephthaloyldichloride at the water/oil interface to prepare four types of microcapsules containing water, i.e., poly(DMAAm-co-DMAPAA-co-AmSt-alt-terephthalic acid) microcapsules, poly(DMAAm-co-DMAPAA-co-AmSt-co-PEG-alt-terephthalic acid) microcapsules, poly (DMAAm-co-METAC-co-AmSt-alt-terephthalic acid) microcapsules, and poly (DMAAm-co-METAC-co-AmSt-co-PEG-alt-terephthalic acid) microcapsules, which will be abbreviated to MC 1, MC 2, MC 3, and MC 4, respectively. It has been predicted that the microcapsule membranes are hydrophilic and soft and have two-sublayer structures from electrophoretic mobility measurements and from the analysis of the data with Ohshima’s electrokinetic theory for soft particles. The outer sublayers of MC 1 and MC 2 are negatively charged and those of MC 3 and 4 are slightly positively charged. Also, the surfaces of MC 1 and MC 2 are harder than those of MC 3 and 4. By PEGylation, the surface charge density in the membranes decreases and the surface becomes softer. It has been found that the membrane of red blood cells (RBC) is also soft and is composed of two-sublayers, the outer sublayer of which is negatively charged and the inner one is positively charged. The interaction of four types of microcapsules with RBC has been studied. It was found that microcapsules with soft surfaces (MC 3 and MC 4) do not interact with RBC, even though the microcapsule surfaces are positively charged and the surface of RBC is negatively charged. On the other hand, microcapsules with negatively charged but harder surfaces (MC 1) interact with RBC to introduce hemolysis. The membrane surface of MC 2, which is obtained by PEGylation of MC 1, becomes softer than that of MC 1 so that the interaction with RBC was weakly suppressed. From these, it was concluded that the dominant factor to control the interaction between synthetic polymer surfaces and biological cell surfaces is not the surface charges carried by the polymer surfaces but the softness of the polymer surfaces.     

X‐ray crystallographic analysis and differential scanning calorimetry of two polymorphic forms of 2,6‐diphenyl‐1,4‐dithiin

2,6‐Diphenyl‐1,4‐dithiin 2 exists in the two polymorphic forms. The dithiin 2L , mp 62–63°C, was assigned as the metastable form, while the dithiin 2H , mp 79–80°C, was assigned as the stable form, mainly on the basis of differential scanning calorimetry (DSC) analysis. X‐Ray crystallographic analysis showed that the largest difference in the molecular structure between 2L and 2H is found in the coplanarity between the benzene ring and the double bond part of the dithiin ring; the benzene ring and the double bond are nearly coplanar for 2L , whereas these are far from being coplanar for 2H . © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:424–427, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20035     

Transitively twisted flows of 3-manifolds

A non-singular C ¹ vector field X of a closed 3-manifold M generating a flow induces a flow of the bundle N X orthogonal to X. This flow further induces a flow of the projectivized bundle of N X. In this paper, we assume that the projectivized bundle is a trivial bundle, and study the lift of to the infinite cyclic covering . We prove that the flow is not minimal, and construct an example of such that has a dense orbit. If is almost periodic and minimal, then is shown to be classified into three cases: (1) All the orbits of are bounded. (2) All the orbits of are proper. (3) is transitive. Received: December 2, 1999     

Sequential collection of selenium(IV) and selenium(VI) by the use of an anion-exchange resin loaded with bismuthiol-II sulphonic acid

A new ligand-loaded anion-exchange resin has been developed which allows determination of Se(VI) and Se(IV) in mixtures of the two. The ligand is a sulphonic acid derivative of bismuthiol-II.     

Determination of germanium by graphite-furnace atomic-absorption spectrometry

The premature loss of germanium as volatile GeO results in low sensitivity and poor reproducibility in the determination of germanium by graphite-furnace atomic-absorption spectrometry. This interference can be eliminated by suppressing the premature reduction of GeO(2) to GeO during the ashing step, and dissociating the germanium oxides into the atoms simultaneously with their vaporization during the atomization step. The premature reduction of GeO(2) to GeO has been successfully prevented by several approaches: (1) diminishing the reducing activity of the graphite furnace by (a) oxidizing the graphite surface and intercalating oxygen into the graphite lattice with oxidizing acids, such as nitric or perchloric, in the sample solution, or (b) using a tantalum-treated graphite furnace; (2) keeping the analyte as germanium (IV) by addition of sodium or potassium hydroxide to the sample solutions.     

Double internal bremsstrahlung in the electron-capture decay of 55Fe

The energy distribution of photons emitted in double internal bremsstrahlung accompanying the electron-capture decay of ⁵⁵Fe has been investigated. For sum photon energies in the range of 44–230 keV and at an emission angle of 90°, the ratio of transition probabilities of double to single internal bremsstrahlung processes has been found to be (5.6±0.5) × 10^?5. The experimental data are compared with the existing theoretical predictions.     

Sensitization of ZnO photoconductivity by chemical modification of surface states

Surface States on ZnO have been investigated through their effect on photoconductivity. Low energy photons (0·7 ～ 1·5 eV) are found to induce a feeble photocurrent in ZnO which is attributable to the direct electron injection from surface levels to the conduction band. A definite correlation has been found between the i.r. induced photocurrent and the intrinsic or the dye sensitized photocurrent excited by UV or visible radiation. It is proposed that phthalic anhydride on ZnO modifies the distribution of surface levels, by a chemical interaction with chemisorbed oxygen. Surface levels originating in chemisorbed oxygen ions are transformed by phthalic anhydride into new levels which are shallower but thermally more stable. These traps are found to enhance the photoconductivity of ZnO. The chemical nature of them and the mechanism of sensitization are discussed.