Experimental study on the free surface deformation in the oxide melt

1 Introduction The convective motion induced by local variations of surface tension along a liquid free surface is called Marangoni convection. Flows driven by a temperature gradient aligned parallel to the free surface are often named thermocapillary convection, which is often a dominating effect in material processing techniques. It is well known for the melt crystal growth that the thermocapillary convection becomes instable at high Marangoni numbers, which gives rise to temperature oscill…     

Isolation of the YAP1 homologue of Candida utilis and its use as an efficient selection marker

The industrially important yeast Candida utilis is widely used in the production of food and medical materials, but its practical host-vector system has not been well developed. In order to construct a food-grade host-vector system, we isolated the YAP1 homologue, CuYAP1, of C. utilis IAM4264 and evaluated its use as a selection marker in transformation. A DNA probe was obtained by PCR using degenerate primers and the CuYAP1-encoding 438 amino acid protein was isolated by hybridization. Although the amino acid identity of Yap1 and CuYap1 was 28.7% as a whole, the characteristic bZip region and two cysteine-rich domains (CRDs) showed a higher homology. CuYAP1 was inserted in a CuGAP1 expression cassette of the C. utilis ARS vector pRI177, and C. utilis AHU3053 was transformed with this plasmid. A number of transformant colonies grew in the presence of cycloheximide, which indicated that CuGAP1-CuYAP1 is an effective selection marker. The transformant also showed higher resistance to other agents, including cadmium and fluconazole. The overexpression of CuYAP1 in S. cerevisiae also resulted in increased resistance to various types of drugs.     

The J-integral fracture criterion under opening and tearing modes and unloading effects

Measurements of $\text{J}$ from certain formulae agree well with compliance measurements for a round notched bar specimen subjected to tensile (Mode I) and torsional (Mode III) loadings. Crack growth resistance curves ($\text{R-}\text{curves}$) obtained by a three parameter technique are compared with those obtained by two current approaches. The $\text{J}{}_{\mathrm{IC}}$ values (Mode I) at initial crack growth are in good agreement with the $\text{j}{}_{\mathrm{IIIC}}$ values (Mode III). In addition, the effect of unloading on fracture toughness is examined.     

Effects of operating potential and temperature on degradation of electrocatalyst layer for PEFCs

The objective of this research work is to clarify essential factors related to degradation of PEFC electrodes. The degradation of Pt catalysts and the carbon support after a daily start and stop (DSS) operation was evaluated separately by measuring the electrochemical active area (S_Pt) and the double layer charging current (I_DL) with cyclic voltammetry without and with CO adsorption on Pt catalyst surfaces, respectively. Corrosion of the carbon support was accelerated mainly by raising the operating potential to 0.90 V, which was observed by increase in I_DL. The high-temperature operation at 90 °C or high-potential operation at 0.90 V resulted in a dramatic decrease in S_Pt. In contrast, it was found that the apparent cell performance was not so degraded probably because the decrease in S_Pt was cancelled by an increase in the proton conductance in the swollen ionomer. The agglomeration of Pt catalyst particles and their migration in the electrolyte membrane were also analyzed by TEM observation after the DSS operations.     

Structure and Thermophysical Properties of Molten BaGe Using Electrostatic Levitation Technique

BaGe alloys with two compositions near their eutectic point form open framework structures called the clathrate structure. These BaGe compounds with the clathrate structure can be made by rapid solidification from their liquid state. However, the formation mechanism of the clathrate structure has not been clarified due to lack of information on their liquid-state structure and properties. Since BaGe alloy melts have very high reactivity, it is difficult to measure the thermophysical properties of them by ordinary methods using a container. Therefore, a containerless technique must be used to measure the thermophysical properties of BaGe melts. Using the electrostatic levitation (ESL) technique as a containerless technique, the thermophysical properties (density, surface tension, and viscosity) of BaGe melts around the eutectic composition were measured in order to clarify the formation mechanism of the clathrate structure, and also the structure of them was observed by using the high-energy X-ray diffraction method combined with ESL. From experimental results, it was observed that the short-range order based on the clathrate structure exists even in the liquid state at the clathrate-forming compositions.     

A rod matrix compensator for small-field intensity modulated radiation therapy: a preliminary phantom study

A compensator made of a tungsten-based rod matrix has been proposed for small-field intensity modulated radiation therapy. The compensator was attached to a 6 MV linac gantry head. The proposed compensator could modulate the X-ray intensity with a step of 10% and a minimum transmission of 2.5%.     

Radiophotoluminescence dosimetry using a small spherical glass: a preliminary phantom study

A radiophotoluminescence dosimetry has been proposed using a spherical silver-activated phosphate glass with a diameter of 1.5 mm. A 6 MV photon dose of 2 Sv (2 Gy) was delivered to 14 spherical glass samples placed between two solid water phantoms at a depth of 10 cm. The samples were positioned within a 20 x 20 mm(2) centred at beam axis to ensure uniform dose absorption. A normalised output from a read-out system was obtained by simultaneously measuring luminescence from a non-irradiated reference and that from an irradiated reference to eliminate background contamination and time-varying fluctuation of the readout system, leading to a normalised standard deviation of 1.8%. A dose up to 3.5 Sv (3.5 Gy) was delivered to three spherical glass samples positioned between two solid water phantoms at a depth of 10 cm. The normalised output increased linearly with the applied dose.     

Rugate filters fabricated by a radio frequency magnetron sputtering system by use of an optical in situ monitoring technique

We propose, for the first time to our knowledge, a new feedback fabrication technique for rugate filters with sinusoidal refractive index distribution. The technique uses an in situ optical monitoring system, in contrast to conventional techniques for rugate filters that are based on time control, which is generally unsuitable for accurate fabrication of a continuous index distribution. We employed a-SiOx:H thin film as the material for the rugate filters because its refractive index can be successively controlled. Using the proposed technique and material, we fabricated near-infrared rugate minus filters having multiple and continuous refractive index distributions. The experimental and calculated spectra were well correlated as a result of applying the proposed feedback fabrication technique.