Effect of REM addition of wire on CO2 gas shielded arc phenomenon

Carbon dioxide (CO₂) gas shielded arc welding is the main arc welding method, but it generates a large amount of spatter during welding. The root cause of spatter lies in the fact that the droplet undergoes repeated irregular shaking. To solve this problem, spatter generation modes were clarified and the effects of polarity and rare earth metal (REM) addition of the wire on CO₂ gas shielded arc welding were investigated. As a result, when welding is performed with an electrode negative (DCEN) polarity using REM added wire, it was found that a conical arc plasma is formed, and the droplet which is transferred from the wire tip to the molten pool is fine and continuous, in what is termed ‘spray transfer’. Thus, spatter generation was reduced to 10% of amount of the conventional CO₂ gas shielded arc welding (from 0.058 to 0.005g/s).     

Magnetic measurements at pressures above 10 GPa in a miniature ceramic anvil cell for a superconducting quantum interference device magnetometer

A miniature ceramic anvil high pressure cell (mCAC) was earlier designed by us for magnetic measurements at pressures up to 7.6 GPa in a commercial superconducting quantum interference magnetometer [N. Tateiwa et al., Rev. Sci. Instrum. 82, 053906 (2011)]. Here, we describe methods to generate pressures above 10 GPa in the mCAC. The efficiency of the pressure generation is sharply improved when the Cu-Be gasket is sufficiently preindented. The maximum pressure for the 0.6 mm culet anvils is 12.6 GPa when the Cu-Be gasket is preindented from the initial thickness of 300-60 μm. The 0.5 mm culet anvils were also tested with a rhenium gasket. The maximum pressure attainable in the mCAC is about 13 GPa. The present cell was used to study YbCu(2)Si(2) which shows a pressure induced transition from the non-magnetic to magnetic phases at 8 GPa. We confirm a ferromagnetic transition from the dc magnetization measurement at high pressure. The mCAC can detect the ferromagnetic ordered state whose spontaneous magnetic moment is smaller than 1 μ(B) per unit cell. The high sensitivity for magnetic measurements in the mCAC may result from the simplicity of cell structure. The present study shows the availability of the mCAC for precise magnetic measurements at pressures above 10 GPa.     

Experiments and Predictions of Soil Desaturation by Air-Injection Technique and the Implications Mediated by Multiphase Flow Simulation

Measures preventing an earthquake-induced soil liquefaction are of significant importance to mitigate the liquefaction hazards. An air-injection technique may be a simple, inexpensive method - this leads the saturated soils to the desaturated by injecting pressurized air, resulting in a higher liquefaction strength and lower susceptibility. The objective of this study is to investigate the evolution of desaturation process during air injection into saturated soil deposits and verify the validity of a multiphase flow simulator if it is capable of being applied for predicting the process as well as the distribution of degree of saturation after the air injection ceased. In this study simplified model tests that simulate the air injection into saturated soils using air-injection probes, are conducted using two different sizes of soil containers. The experiments using the small container are aimed to examine the nominal rates and magnitudes of the soil desaturation driven by air injection, whilst those with the large container are performed to obtain not only the rates and magnitudes but also the distributions of the desaturated zones within the soil. The results obtained indicate, although clearly depending on the physical properties of targeted soils, that the evolution of desaturation is strongly controlled by the air pressures injected and the soil permeabilities. Numerical analyses are also conducted using a multiphase flow simulator to describe the evolution of the soil desaturation, and to examine the applicability of the model as a prediction tool enabling an evolution of desaturation in situ to be followed with time and space. Predictions show a relatively good agreement with the experimental measurements regarding the rates, magnitudes, and distribution of desaturation specifically for the small-container experiments although predictions of desaturated domain slightly overestimate the measurements for the large-container experiments. Thus, this study indicates that the numerical model described is applicable to field problems when the soil properties in terms of flow transport are well-constrained.     

Stability of metastable tetragonal ZrO2 in compound powders and nucleation arguments

ZrO₂-SiO₂ (11) mixtures and ZrO₂ particles were prepared by a sol-gel method from the solutions of ZrOCl₂·8H₂O (ZOC) + Si(OC₂H₅)₄ (TEOS) + C₂H₅OH and ZOC + C₂H₅OH + H₂O + NH₄Cl systems, respectively. Quantitative changes of phase crystallized by heating were compared with those of ZOC + TEOS + H₂O and/or ZrO(NO₃)₂ · 2H₂O + H₂O systems, respectively. The stability of metastable tetragonal (mt)-ZrO₂ particles depends on the Young's modulus of the SiO₂ matrix. Transition metal oxides existing on the interface assisted in stabilizing mt-ZrO₂. The order of the assistance agreed with that of the relative field strengths of their oxides. A relationship between the ionic radius and the volatility of anionic groups, and the difficulty of nucleation for the martensitic transformation accompanying a shear stress, is suggested.     

Novel gold-capped nanopillars imprinted on a polymer film for highly sensitive plasmonic biosensing

Herein, a nanoporous alumina was fabricated to use as a mold in transforming nanopillar structures onto a thin film polymer by thermal nanoimprint lithography (NIL). The size of the pores was successfully controlled by varying the applied voltages and etching time. These nanoporous structures were transferred to the Cyclo-olefin polymer (COP) film surface from the porous mold by a thermal nanoimprinting process. A plasmonic substrate was fabricated by sputtering a thin layer of gold onto this nanopillar polymer structure, and the refractive index response in a variety of media was evaluated. Finally, the biosensing capacity of this novel plasmonic substrate was verified by analysis of Human immunoglobulin and achieved a minimum detection limit of 1.0 ng/mL. With the advantages of mass production with consistent reproducibility stemming from the nanoimprint fabrication process, our gold-capped polymeric pillars are ready for the transition from academic interest into commercialization systems for practical use in diagnostic applications.     

ADSORPTION BEHAVIOR OF COBALT( II) IONS ON LAYERED DIHYDROGEN TETRATITANATE HYDRATE FIBERS IN AQUEOUS SOLUTIONS IN THE RANGE FROM 298 to 523 K

The adsorption properties of cobalt(II) ions have been studied on layered dihydrogen tetratitanate hydrate fibers, H₂Ti₄O₉,?nH₂O, in the temperature range from 298 to 523?K. The distribution coefficients of the adsorption of cobalt (II) ions were increased with increasing temperatures up to 367?K, but were decreased in the temperature range between 367 and 523?K. The X-ray powder diffraction patterns of the fibers indicate that the fibers hold layer structure up to 367?K, but change to low crystalline anatase or its precursor above that temperature. It is notable that the material has the capability of cobalt (II) adsorption even at 523?K, although the maximum is present at 367?K.     

Magnetic Field Effect on Chemical Compositions of Magnetic Aerosol Particles Synthesized Photochemically from a Gaseous Mixture of Iron Pentacarbonyl and Trimethylsilyl Azide

Under intense UV light irradiation with an Nd:YAG laser at 355 nm, a gaseous mixture of iron pentacarbonyl (Fe(CO)₅) and trimethylsilyl azide (TMSAz) produced aerosol magnetic particles with diameters of 50–100 nm. Two photon absorption of TMSAz and Fe(CO)₅ took place efficiently to produce trimethylsilyl nitrene and iron carbonyls (Fe(CO) _n n = 1–4). In cases where a partial pressure of TMSAz was high, nucleation reactions of aerosol particles proceeded via chemical reactions between trimethylsilyl nitrene and two iron carbonyls, resulting in bridging between two iron carbonyls by silyl nitrene. In cases where a partial pressure of TMSAz was low, the nucleation reactions proceeded via chemical reactions between two iron carbonyls, resulting in the formation of di-iron carbonyls with bridging >C?O group. Both of these nucleation reactions took place concurrently during aerosol particle formation. From FT-IR spectral change of sedimentary particles produced under an external magnetic field of up to 5 T, it was found that application of an external magnetic field accelerated the latter chemical reaction to result in the appearance of bridging ν(>C?O) band in FT-IR spectrum of the magnetic particles.

Copyright 2013 American Association for Aerosol Research     

ION-EXCHANGE PROPERTIES OF HYDROUS TITANIUM DIOXIDE WITH A FIBROUS FORM OBTAINED FROM POTASSIUM DITITANATE

ABSTRACT

Ion-exchange properties of a new type of hydrous titanium dioxide with a fibrous form, which was obtained from potassium dititanate (K₂O(TiO₂)2), have been studied. The pH titration curve snowed that this material behaved as a bifunctional ion-exchanger. Distribution coefficients of some divalent metal ions on this material were measured as a function of pH and the selectivity series were found to be Ba > Sr > Ca > Mg for alkaline earth metal ions and Cu > Zn > Mn > Co > Ni for divalent transition metal ions. Large separation factors were obtained between some metal ion pairs and the mutual separations such as Cu from Sr, Ca, Mg, Co and Ni, and Mg from Ba and Zn have been achieved on columns of this material.     

Nanoscale molecular cavity in crystalline polymer membranes studied by molecular dynamics simulation

The size, shape, and connectivity of cavities in the crystals of syndiotactic polystyrene were investigated by molecular dynamics simulation. Cluster analysis of the free volume in the crystals clearly reveals the cavity structures: large individual holes are in an orderly manner connected by narrow channels. We call such a cavity structure a ‘molecular cavity’. The diffusion behavior and solubility of gases in the molecular cavity were also simulated. The extremely high solubility of a larger gas and the controllable diffusion path in the narrow channels proved the applicability of the concept of the molecular cavity to high performance separation membranes.     

Dietary CLA and DHA modify skin properties in mice

This study investigated the influence of PUFA on the properties of mouse skin. Mice (3 wk old) were given free access to oils high in linoleic acid, CLA, or DHA for 4 wk. At the end of the experiment, their skins were compared by both biochemical and histological methods. No significant differences in lipid and collagen contents were detected among treatments, although the FA composition in the skin was altered depending upon the FA composition of the supplemented oils. Electron microscopy revealed that the subcutaneous tissue layers in the CLA and DHA groups were significantly thinner than that in the high linoleic acid group, whereas no differences in the thickness of dermis layers were observed among the three groups. These results suggest that skin properties in mice are readily modified by dietary FA sources within 4 wk of dietary oil supplementation.