XPS determination of compositions of alloy surfaces and surface oxides on mechanically polished iron-chromium alloys

Using the XPS technique, the compositions of the alloy surface and the surface oxide on mechanically polished iron-chromium alloys were studied. For quantitative analysis, the ratio of photo-ionization cross section of Fe $\text{2p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ electrons to that of Cr $\text{2p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ electrons was estimated as 1.35 for Al Kα_1,2 radiation. Assuming a homogeneous oxide layer, the thickness of the oxide layer and compositions of the alloy surface and the surface oxide were simultaneously determined. The results showed no enrichment of chromium or iron either in the oxide layer or the alloy surface. Results on binding energies were also given.     

Dielectric behavior of non-spherical cells in culture

OBJECTIVE: To determine whether histological analysis of six multiple random biopsies of the gland or analysis of only one biopsy provides a good estimate of the different components of the hyperplastic gland compared with the results obtained from tissue specimens (reference values). MATERIALS AND METHODS: The various components of prostate tissue obtained from 30 men undergoing suprapubic adenomectomy were investigated. The histological analysis was performed on multiple tissue specimens reflecting adenoma (reference values) and on one and six biopsies performed at random on the enucleated material of the hyperplastic gland. Immunohisto chemistry using anti-actin as a label of smooth muscle and specific histological staining coupled with computer-assisted quantitative morphometric analysis was used to ascertain the histological composition of the prostate. RESULTS: The mean ( +/- SD) area densities obtained from tissue specimens were 34.1 +/- 5%, 32.4 +/- 6.9%, 17.6 +/- 4.5% and 15.9 +/- 5.5% of smooth muscular and fibrous tissue, and epithelium and glandular lumen, respectively. The mean ratio of stromal to epithelial hyperplasia averaged 4.05 +/- 1.73. Both one and six biopsies gave a good estimate of fibrous tissue and glandular epithelium, but the percentage of smooth muscles was overestimated and the percentage of glandular lumen was underestimated. There was a significant relation between the prostate area densities of glandular epithelium (r = -0.41, P < 0.05), the percentage area density of prostate smooth muscle (r = 0.43, P < 0.05), and the weight of enucleated adenoma. No correlation was found with prostate-specific antigen (PSA). CONCLUSION: It seems feasible to propose medical treatment of benign prostatic hyperplasia (BPH) based on the histological composition of the prostate gland. One biopsy, reflecting in good proportions the nature of the adenoma, would be used to provide insight into the pathogenesis and therapy of BPH.     

Design of whitelight laser based on cathode fall theory

A method is proposed to design a hollow-cathode type whitelight laser by applying the cathode fall theory. Several design examples and their oscillation characteristics are presented. The concentric-cylinder-type laser tube is found to be suitable for a long life, high power green laser, but some difficulties exist in its use as a white-light laser. The flute-type laser tube, however, appears to be suitable as a whitelight laser.     

LASER AND ELECTRON BEAM PROCESSING OF AMORPHOUS SURFACE ALLOYS ON CONVENTIONAL CRYSTALLINE METALS

During last fifteen years various superior surface characteristics including extremely high corrosion resistance and unique electrocatalytic activity have been found for novel melt-spun ribbon-shaped amorphous alloys. Preparation of those amorphous alloys as surface alloys covering bulk conventional crystalline metals has been eagerly awaited for the purpose of utilizing their superior surface characteristics. This is a review of efforts devoted to developing methods for processing amorphous surface alloys by instantaneous melting of a very restricted volume of the surface by irradiation with a CO₂ laser or electron beam and subsequent self quenching by the cold bulk substrates. Processing of a wide area by these high energy density beams requires heating the previously amorphized phase, which is easily crystallized by heating. Consequently, high energy density beam processing is most difficult among various methods for preparation of thermodynamically metastable amorphous alloys. Nevertheless, various amorphous surface alloys have been successfully prepared. The materials consisting of the amorphous surface alloys and bulk crystalline metals are quite suitable for corrosion resistant materials and electrodes for electrolysis of aqueous solutions. A comparison of CO₂ laser and electron beam processing showed the superiority of the latter to the former because of a significantly shorter processing time.     

Preparation of aluminium hydroxide by reacting sodium aluminate solutions with mineral acid

The preparation of aluminium hydroxide from sodium aluminate solutions by varying the alkaline concentration at a fixed molar ratio of Na₂O: Al₂O₃ has been investigated on addition of hydrochloric or nitric acids. The resulting materials have been examined by X-ray diffraction study, infrared spectrophotometry, thermogravimetrical and differential analyses. As a result, it was found that precipitates generally exist as pseudoboehmite or bayerite, but the formation of bayerite is enhanced by a low rate of addition of acid, higher temperature or higher alkaline concentration. In this case, the composition of the precipitates was little influenced at different molar ratios of Na₂O: Al₂O₃. When the precipitates from sodium aluminate solutions at low and higher alkali concentrations were aged in the mother liquors, pseudoboehmite therein transformed to hydrargillite and bayerite, respectively.     

3D structuring of dense alumina ceramics using fiber-based stereolithography with interparticle photo-cross-linkable slurry

In this paper, we demonstrated optical fiber-based stereolithography of alumina ceramics using concentrated slurry with low monomer content for enabling rapid firing of the printed green objects. Photo-cross-linkable alumina slurries were designed using a partial complex of polyethyleneimine and oleic acid (PEI-OA) as reactive polymer dispersants and multifunctional acrylates (MA) as monomers. The effects of the processing parameters, such as oleic acid contents, MA contents, particle contents, and particle sizes, on photocuring properties were systematically investigated. We found that the reactive amine sites of PEI-OA attached to particles and MA volume concentrations in the liquid phase were the most dominant factors to improve the photocuring properties. Therefore, a slurry composed of larger alumina particles with higher solid contents and PEI-OA with lower OA contents was more favorable for achieving photocuring under reduced MA content. The designed photocurable slurry was then applied to ceramic stereolithography using optical fiber. 3D alumina green parts were drawn by passing blue laser beam through an optical fiber in a droplet of photocuring slurry and dense sintered alumina were successfully fabricated by rapid drying (<10 min) and debinding (<1 h) without any structural collapse.     

Near lossless coding of sparse histogram images based on zero-skip quantization

Multimedia Tools and Applications - This paper introduces a zero-skip quantization (ZS.Q) scheme for the near lossless coding of sparse histogram images. Increases in the range of pixel values and...     

Combined ab initio/CALPHAD modeling of fcc-based phase-equilibria in the Ir–Nb system

A preliminary thermodynamic assessment of the Ir–Nb system, one of the key binary systems of the Ir-based refractory superalloys, has been performed by combining ab initio calculations and the CALPHAD (CALculation of PHAse Diagrams) technique. The ground-state formation enthalpies have been calculated by the full-potential linearized augmented plane wave method. The free energies at finite temperatures have been estimated using the cluster variation method, where the effective cluster interaction energies have been extracted from the formation enthalpies by the cluster expansion method. The liquid and A1 phases are modeled as substitutional solutions. The L1₀ and L1₂ phases are described using the four-sublattice model with the formula (Ir,Nb)_1/4(Ir,Nb)_1/4(Ir,Nb)_1/4(Ir,Nb)_1/4, while other solid phases are not considered in the present assessment. The obtained parameter set reproduces well the characteristic features of the experimental phase diagram and thermodynamic quantities.