Characteristics of surface oscillation on high speed liquid Li jet

In the International Fusion Materials Irradiation Facility (IFMIF), high speed liquid lithium (Li) wall jet will be used as target irradiated by two deuteron beams of 125 mA at 40 MeV. To obtain knowledge of Li flow behavior, we have been studying on the surface wave characteristics experimentally using the liquid metal Li circulation loop at Osaka University. In this present study, the characteristic of surface oscillation on high speed liquid Li jet were examined. The free surface oscillation of Li flow was measured by an electro-contact probe apparatus, which detects electric contacts between a probe tip and Li surface. It was installed at 175 mm and 15 mm downstream from the nozzle exit to see influence of the initial growth of surface waves. The wave height of free surface waves was obtained from contact signal. While at 15 mm region the flow surface is very smooth covered with small waves in amplitude, the surface waves are developed sufficiently at the 175 mm. In the case of the velocity of 15 m/s, the maximum wave height reaches 4.8 mm. Heat deposition was estimated on the target back-plate with using the present statistical wave data.     

Characteristic fungi observed in the fermentation process for Puer tea

The fermentation process for Puer tea, a unique Chinese tea produced by microbial activities, was investigated by physicochemical and microbial analyses. The temperature of a windrow-shaped pile of tea leaves increased instantly at the beginning of fermentation and stayed at around 50 degrees C until day 35, then decreased gradually to room temperature at the end of fermentation, at day 50. Water content was approximately 30% or less, and pH value was maintained at a weakly acidic level of 5 to 6 throughout the fermentation, conditions that are favorable for propagation of fungi including yeasts. Polyphenol, the characteristic component of tea leaves, decreased continually from day 10 to day 50 of fermentation, corresponding well with the fact that the total concentration of fungi steadily increased during the same period. PCR followed by denaturing gradient gel electrophoresis (DGGE) analysis revealed that there were at least two major fungi: Aspergillus niger, which has been well known among Puer tea manufacturers, and Blastobotrys adeninivorans, which is newly recognized in the present study. Furthermore, both of these fungi were observed in the DGGE fingerprint when other commercial Puer tea products were analyzed. These results prompted us to deduce that both A. niger and B. adeninivorans play important roles in the nutritional enhancement of tea leaves during Puer tea fermentation.     

Twisted Crystalline Organic Semiconductor Photodetectors

Optoelectronic properties of anisotropic crystals vary with direction requiring that the orientation of molecular organic semiconductor crystals is controlled in optoelectronic device active layers to achieve optimal performance. Here, a generalizable strategy to introduce periodic variations in the out-of-plane orientations of 5,11-bis(triisopropylsilylethynyl)anthradithiophene (TIPS ADT) crystals is presented. TIPS ADT crystallized from the melt in the presence of 16 wt.% polyethylene (PE) forms banded spherulites of crystalline fibrils that twist in concert about the radial growth direction. These spherulites exhibit band-dependent light absorption, photoluminescence, and Raman scattering depending on the local orientation of crystals. Mueller matrix imaging reveals strong circular extinction (CE), with TIPS ADT banded spherulites exhibiting domains of positive or negative CE signal depending on the crystal twisting sense. Furthermore, orientation-dependent enhancement in charge injection and extraction in films of twisted TIPS ADT crystals compared to films of straight crystals is visualized in local conductive atomic force microscopy maps. This enhancement leads to 3.3- and 6.2-times larger photocurrents and external quantum efficiencies, respectively, in photodetectors comprising twisted crystals than those comprising straight crystals.     

Fluorescence Imaging Using Enzyme-Activatable Probes for Detecting Diabetic Kidney Disease and Glomerular Diseases

A clear identification of the etiology of glomerular disease is essential in patients with diabetes. Renal biopsy is the gold standard for assessing the underlying nephrotic pathology; however, it has the risk for potential complications. Here, we aimed to investigate the feasibility of urinary fluorescence imaging using an enzyme-activatable probe for differentiating diabetic kidney disease and the other glomerular diseases. Hydroxymethyl rhodamine green (HMRG)-based fluorescent probes targeting gamma-glutamyl transpeptidase (GGT) and dipeptidyl-peptidase (DPP) were used. Urinary fluorescence was compared between groups which were classified by their histopathological diagnoses (diabetic kidney disease, glomerulonephritis, and nephrosclerosis) as obtained by ultrasound-guided renal biopsy. Urinary fluorescence was significantly stronger in patients with diabetic kidney disease compared to those with glomerulonephritis/nephrosclerosis after DPP-HMRG, whereas it was stronger in patients with nephrosclerosis than in patients with glomerulonephritis after GGT-HMRG. Subgroup analyses of the fluorescence performed for patients with diabetes showed consistent results. Urinary fluorescence imaging using enzyme-activatable fluorescence probes thus represents a potential noninvasive assessment technique for kidney diseases in patients with diabetes.     

Enhancement of the nitrogen fixation efficiency of genetically-engineered Rhizobium with high catalase activity

The vktA catalase gene, which had been cloned from Vibrio rumoiensis S-1^T having extraordinarily high catalase activity, was introduced into the root nodule bacterium, Rhizobium leguminosarum bv. phaseoli USDA 2676. The catalase activity of the vktA-transformed R. leguminosarum cells (free-living) was three orders in magnitude higher than that of the parent cells and this transformant could grow in a higher concentration of exogenous hydrogen peroxide (H₂O₂). The vktA-transformant was inoculated to the host plant (Phaseolus vulgaris L.) and the nodulation efficiency was evaluated. The results showed that the nitrogen-fixing activity of nodules was increased 1.7 to 2.3 times as compared to the parent. The levels of H₂O₂ in nodules formed by the vktA-transformant were decreased by around 73%, while those of leghemoglobins (Lba and Lbb) were increased by 1.2 (Lba) and 2.1 (Lbb) times compared with the parent. These results indicated that the increase of catalase activity in rhizobia could be useful to improve the nitrogen-fixing efficiency of nodules by the reduction of H₂O₂ content concomitantly with the enhancement of leghemoglobins contents.     

Gas transport in poly(vinyl benzoate)

The transport parameters of nine gases (O₂, N₂, CO₂, He, Ne, Ar, Kr, Xe) through poly(vinyl benzoate) (PVB) have been measured by the time lag method above and below the glass transition temperature, T_g The results are compared with the related data of poly(vinyl acetate) (PVAc) by Meares and discussed as the effect of replacement of the methyl group by a phenyl group in the side chain of PVAc. Small molecules, such as H₂, He, and Ne, diffuse more easily through PVAc than PVB, but the tendency is reversed for the larger gases. The activation energy for diffusion is proportional to the squares of the Lennard–Jones diameters of the gases below the T_g. On the other hand, above the T_g, linear relation is obtained to the cubes of the diameters. Solubility behavior is discussed by comparing the heats of solution for PVB and PVAc.     

Study on physical properties of poly(vinyl acetate) emulsion films obtained in batchwise and in semicontinuous systems

Emulsion polymerization of vinyl acetate was carried out batchwisely or semicontinuously in the presence of a nonionic surfactant or poly(vinyl alcohol) (PVA). From the investigation of degrees of polymerization of poly(vinyl acetate) (PVA_c) during the course of polymerization and those of corresponding hydrolyzed PVA, it was clarified that the degrees of polymerization of the batchwise system are much larger than those of the semicontinuous system, and long branches and shorter branches are formed in the batchwise and the semicontinuous systems, respectively. The emulsion films obtained batchwisely had properties with better tensile strengths by two to four times (nonionic system) and 1.5 times (PVA system) than those obtained semicontinuously. The former films revealed a better water-resistant nature compared with the latter films. © 1993 John Wiley & Sons, Inc.     

Oxidation behavior of isoprene polymers and butadiene polymers

The oxidation behavior of cis-1,4-polyisoprene, emulsion polyisoprene, emulsion isoprene/styrene copolymers, and emulsion butadiene/styrene copolymers by heat aging or ultraviolet irradiation has been investigated from the change of gel fraction and molecular weight distribution. It was determined that the oxidation behavior of both isoprene and butadiene polymers is strongly dependent on the composition of the polymers as well as on the microstructure of the polymers. In the case of oxidation by heat aging, the probability ratio of chain scission to crosslinking of both isoprene and butadiene copolymers increases gradually with increasing styrene fraction. In the case of oxidation by ultraviolet irradiation, isoprene copolymers show a remarkable increase in the probability ratio of chain scission to crosslinking, whereas butadiene copolymers show substantially no change with increase in styrene fraction. It was also demonstrated that both isoprene and butadiene polymers show a greater tendency for crosslinking with oxidation by ultraviolet irradiation than with oxidation by heat aging.