Thermodynamics of phosphorus in molten Si-Fe and Si-Mn alloys

The thermodynamics of phosphorus in molten Si-Fe and Si-Mn alloys has been investigated at 1723 K by equilibrating the alloys in a controlled phosphorus partial pressure. The activity coefficient of phosphorus in each alloy shows a maximum value at a certain composition due to a strong interaction between silicon and iron and between silicon and manganese. Interaction coefficients between phosphorus and iron in molten silicon were found to be ε _P ^Fe =7.43 and ρ _P ^Fe =−16.4 (0≦X _Fe≦0.65), and those between phosphorus and manganese were ε _P ^Mn =12.0 and ρ _P ^Mn =−22.2 (0≦X _Mn≦0.5). Further discussion has revealed that the Si-Fe-P and Si-Mn-P systems approximately conform to a regular solution within the composition ranges investigated in the present work.     

Superhydrophilicity on nano-rough carbon surfaces achieved by hyperthermal oxygen-atom beam exposure

In order to investigate a method to increase hydrophilicity on nano-rough carbon surfaces, a nano-rough surface of C₆₀ film and an atomically flat surface of highly oriented pyrolytic graphite (HOPG) were oxidized by hyperthermal oxygen-atom beam exposure and the hydrophilicities of the surfaces were investigated. Superhydrophilicity were achieved on these exposed carbon surfaces, which had low O/C ratio of approximately 28% and surface roughness (Ra) of approximately 3 nm. The direct oxidations on sp² bonded carbon atoms (basal plane) of these two carbon materials by the exposure of hyperthermal O-atom beam would contribute the superhydrophilicity.     

Influence of magnesia on sintering stress of alumina

The sintering stress and the densification of MgO-doped Al₂O₃ were measured with a self-loading apparatus and a thermomechanical analyzer, respectively. The densification started at 950 °C and finished at about 1450 °C. The measured surface tensions were 0.7–0.8 N m⁻¹ in the intermediate sintering stage but drastically decreased to 0.2 N m⁻¹ in the final stage of sintering.     

EVALUATION OF LIQUID-LIQUID PARTITION COEFFICIENTS OF MULTTDENTATE AMINES BY SCALED PARTICLE THEORY

ABSTRACT

For some aliphatic and aromatic bidentate amines, e.g., ethylenedi-amine derivatives, which were used in the synergistic extraction system, the liquid-liquid partition coefficients (P) were measured between benzene and water phases and discussed together with other aliphatic and aromatic multidentate amines by using the scaled particle theory (SPT). The contributions of three kinds of Gibbs energies, i.e, the cavity formation energy (G¯_h), the dispersion energy (G¯_dis) and hydrogen-bonding energy (G¯_h), to the P values were successfully evaluated. The main factor to determine the P value was G¯_h (10–55 kJ/mol) in the aqueous phase, but the contributions of G¯_c (6–15 kJ/mol) and G¯_dis (6–28 kJ/mol) were not negligibly small.     

Plasticization of cellulose diacetate by reaction with maleic anhydride,glycerol, and citrate esters during melt processing

To accomplish the stable internal plasticization of cellulose diacetate (CDA), maleic anhydride (MAH) and glycerol (Gly) were used as reactive plasticizers. The plasticization method used was based on a melt‐processing reaction of CDA with MAH and Gly. MAH and Gly (MG)‐plasticized CDA showed stiff and brittle properties; that is, low elongation at break and high modulus. Thus, citrate esters were used as coplasticizers to improve physical properties. The resulted plasticized materials were optically clear, and showed attractive mechanical properties. The grafting of MG oligoesters to the free hydroxyl groups in CDA and their homo‐oligomerization were accelerated by two‐step kneading process, and verified by FTIR and GPC measurements. Differential scanning calorimeter (DSC) analysis revealed decreases of 80–100°C in the glass transition temperature (T_g) of CDA by these plasticizations. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 243–250, 2001     

The influence of basicity on the solubility of platinum in oxide melts

The solubility of platinum in molten BaO-CuO _x , BaO-MnO _x , CaO_satd-SiO₂-FeO _x , KO_0.5-SiO₂, NaO_0.5-SiO₂, and NaO_0.5-PO_2.5 fluxes has been measured in order to seek a measure of the basicity of highly basic fluxes containing transition metal ions and to clarify the chemical behavior of platinum in those melts. The solubility of platinum increases with increasing content of basic oxide in highly basic fluxes, suggesting that it may be a good indicator of the basicity of highly basic fluxes containing transition metal ions. The solubility of platinum in the KO_0.5-SiO₂, NaO_0.5-SiO₂, and NaO_0.5-PO_2.5 melts has a minimum value, and it is suggested that a platinum is amphoteric: it exists as a platinum cation in an acidic flux and does as a platinate ion in a basic flux.     

Electron microscopic observation of photoreceptor cells in directly inserted anesthetized Drosophila into a high‐pressure freezing unit

The high‐pressure freezing (HPF) technique is known to cryofix water‐containing materials with little ice‐crystal formation in deep depths compared with other freezing techniques. In this study, HPF for anesthetized living Drosophila was performed by placing them directly on the carrier of the HPF unit and exposing them to light. Frozen Drosophila were freeze substituted, and their compound eyes were examined by transmission electron microscopy. The ultrastructures of ommatidia composed of photoreceptor cells were well preserved. The location of the cytoplasmic organelles inside the photoreceptor cells was observed. In some photoreceptor cells in ommatidia of the light‐exposed Drosphila, the cytoplasmic small granules were localized nearer the base of rhabdomeres, compared with those of the nonlight‐exposed Drosophila. Thus, HPF with the direct insertion of living Drosophila under light exposure into the HPF machine enabled us to examine changes to functional structures of photoreceptor cells that occur within seconds.     

The redox equilibria of copper ions in the molten silicate fluxes as a measure of basicity

The redox equilibria of copper ions in the molten NaO_0.5-SiO₂, NaO_0.5-NaF-SiO₂, NaO_0.5-CaO-SiO₂, CaO-CaF₂-SiO₂, CaO-MgO-SiO₂, and CaO-SiO₂ systems have been measured in order to seek a new measure of flux basicity. The Cu²⁺/Cu⁺ ratio decreases with increasing the content of basic oxide. The correlations between the Cu²⁺/Cu⁺ ratio and other refining indexes, such as carbonate, sulfide, and phosphate capacities, CaO activity, and theoretical optical basicity are discussed.     

Atomic origins of the high catalytic activity of nanoporous gold

Distinct from inert bulk gold, nanoparticulate gold has been found to possess remarkable catalytic activity towards oxidation reactions. The catalytic performance of nanoparticulate gold strongly depends on size and support, and catalytic activity usually cannot be observed at characteristic sizes larger than 5 nm. Interestingly, significant catalytic activity can be retained in dealloyed nanoporous gold (NPG) even when its feature lengths are larger than 30 nm. Here we report atomic insights of the NPG catalysis, characterized by spherical-aberration-corrected transmission electron microscopy (TEM) and environmental TEM. A high density of atomic steps and kinks is observed on the curved surfaces of NPG, comparable to 3-5 nm nanoparticles, which are stabilized by hyperboloid-like gold ligaments. In situ TEM observations provide compelling evidence that the surface defects are active sites for the catalytic oxidation of CO and residual Ag stabilizes the atomic steps by suppressing {111} faceting kinetics.     

The effect of sensitizing dyes for photo as antioxidants on the autoxidation of methyl linoleate

The sensitizing dyes for photo which are cyanine homologues have been used as medicine and cosmetics. Their uses are widespread. The authors expected that these dyes might serve as antioxidants by a radical termination mechanism such as hydroperoxy radicals added to the many conjugated double bonds which exist in the dyes. Determination of the induction period by the weighing method confirmed that some sensitizing dyes for photo are available as antioxidants in the autoxidation of methyl linoleate. Therefore, these dyes may serve as new types of antioxidants.