Characteristics of neutralization of acids by newly isolated fungal cells

Soil microorganisms play an important role in maintaining soil pH at levels suitable for other soil organisms. To clarify the biological neutralization mechanism in soil, we isolated soil microorganisms showing a high ability to neutralize acids and studied their characteristics. From our taxonomic study, three isolated strains were identified as filamentous fungi, namely Mucor sp., Aspergillus fumigatus, and Aureobasidium pullulans. These strains could secrete basic materials, such as ammonia, for neutralization, grow in the medium at pH 4.0 and increase the pH of the medium to approximately 8.0. These microbial cells could neutralize not only nitric acid but also sulfuric and hydrochloric acids. The strains could also grow by utilizing nitric acid as a sole nitrogen source. In the soil containing these organisms, the pH was maintained in the neutral range by the buffering action of basic materials that they secrete. These results suggest that these fungal cells are useful for protecting the soil from acidification by acid rain.     

Pattern modification of a neuronal network for individual-cell-based electrophysiological measurement using photothermal etching of an agarose architecture with a multielectrode array

A new type of individual-cell-based on-chip multielectrode array (MEA) cell-cultivation system with an agarose microchamber (AMC) array for topographical control of the network patterns of a living neuronal network has been developed. The advantages of this system are that it allows control of the cell positions and numbers for cultivation using AMCs, as well as easy and flexible control of the pattern of connections between the AMCs through photothermal etching where a portion of the agarose layer is melted with a 1480 nm infrared laser beam. With adequate laser power, narrow micrometer-order grooves (microchannels) can easily be fabricated that can be used to combine neighbouring AMCs to enable topographical control of the neural network pattern. Using this system, an individual-cell-based neural network pattern was formed of rat hippocampal cells within the AMC array without cells escaping from the electrode positions in the microchamber during an eight-day cultivation, and could record cell firing in response to 1.5 V, 500 kHz stimulation through an electrode. This demonstrated the potential of the on-chip AMCMEA cell cultivation system for long-term single-cell-based electrophysiological measurement of a neural network system.     

Development and applications of a compact hybrid tabletop terawatt chirped-pulse amplification Ti:sapphire-Nd:glass laser for x-ray lasing and harmonic generation

A hybrid tabletop (2 m x 3 m) terawatt chirped-pulse amplification Ti:sapphire-Nd:glass laser (1054 nm, 475 fs, 500 mJ, 9 x 10(17) W cm(-2)) has been developed for laser-matter experiments. An overall gain factor of 10(10) was achieved for the laser. The results of laser applications in the studies of soft-x-ray Ni-like Mo 18.9-nm lasing and of harmonic generation from solid surfaces are presented.     

Identification of volatile flavor compounds developed during storage of a deodorized hydrogenated soybean oil

Hydrogenated soybean oil, even after it has been thoroughly deodorized, will develop a characteristic, objectionable flavor known as hydrogenation flavor during storage. The volatile compounds in such an oil were isolated, fractionated by gas chromatography, and the gas chromatographic fractions identified by IR and mass spectrometry. A total of 48 compounds was identified. Among them, 2-trans-6-trans-octadienal, and higher alcohols and lactones, appeared to play an important role in contributing to the hydrogenation flavor.     

Effects of low-dose cadmium exposure on biological examinations

We conducted an epidemiological study to investigate the effects of low-dose cadmium (Cd) exposure on human health in a specific area of a town in Japan where low Cd concentration was detected in rice. We compared clinical findings, urinary and whole blood Cd concentrations, and indicators of renal dysfunction between the polluted area and the control area. The study employed 44 men and 54 women from the polluted area and 21 men and 29 women from the control area. In urine analysis, as indicators of Cd exposure and possible related renal dysfunction, Cd, beta(2)-microglobulin (beta(2)-MG), alpha(1)-microglobulin (alpha(1)-MG), N-acetyl-beta-D-glucosaminidase (NAG), total protein, inorganic phosphorus, lysozyme and creatinine were quantitatively measured. In blood analysis, serum IP and creatinine and whole blood Cd were measured. No case of renal dysfunction due to Cd exposure was confirmed. However, both the urinary and whole blood Cd of the polluted area were significantly higher than those of the control area for both sexes. Urinary beta(2)-MG did not differ between the two areas. For women, urinary alpha(1)-MG was significantly higher in the polluted area than in the control area. In correlation analysis, beta(2)-MG, alpha(1)-MG and NAG, were positively correlated with both of urinary and whole blood Cd for men and women in the polluted area except for between urinary beta(2)-MG and urinary Cd for men. In the control area, the sole positive correlation observed was between urinary beta(2)-MG and whole blood Cd for men. We then examined the determinants of variations of parameters in urinary and blood tests. Potential determinants were age, sex, body mass index, an indicator of smoking habits (cigarette index) and the index of estimated Cd intake from rice (Cd-rice-index). Cd-rice-index was expressed as the product of Cd concentrations in homegrown rice multiplied by daily frequency multiplied by duration (years) of residence in the polluted area. In multiple regression analysis, whole blood Cd was independently associated with Cd-rice-index, age and gender. Variations in whole blood Cd accounted for a substantial portion of the variations in urinary Cd, although they were less influential in older individuals. Whole blood Cd was the sole independent variable related to variations in urinary beta(2)-MG. Cd-rice-index accounted for a portion of the variance in urinary NAG, while age was a more powerful determinant. It was thus revealed that the consumption of homegrown rice polluted with Cd in low concentration resulted in an elevation of whole blood Cd level and consequent increase in urinary Cd level. However, it was not clearly elucidated that the excretion of urinary low-molecular microglobulins could increase significantly in response to slight elevation of Cd body load.     

Profile structure of magnetic flux lines in type-II superconductor from a rectangular electron hologram

Profile magnetic configuration of a quantized flux line and flux-line lattice penetrating a type-II superconductor thin foil, niobium, was observed by electron holography and Lorentz microscopy using a 300 kV field-emission electron microscope. Each single flux line was distributed periodically as lattice structure in the mixed state just below its critical temperature of 8.5 K, while at low temperature of 5 K the flux lines were weakly bound as bundles. In order to observe the flux-line distribution over a wide area, discrete Fourier transform reconstruction in the holography was extended for a rectangular area without loss of information and data precision.     

New scheme for calculation of annular dark-field STEM image including both elastically diffracted and TDS waves

A new scheme of calculation of high-angle annular dark-field STEM image, capable of including both elastically diffracted and thermal diffuse scattering waves, has been presented by a combination of Pennycook's and Nakamura's methods. The new scheme has been demonstrated for image simulations of Si(011) as functions of thickness, defocus values and detector angles. In the present method, the TDS electron intensities are treated in the same way as in Pennycook's method, having a clear physical picture of its origin and reflecting the atom configuration in the systems. For the case of Si(011), it has been confirmed that at the detector angle of 60 to 160 mrad, which is usually applied, the image becomes highly incoherent, and even the image formed only from SOLZ beams becomes incoherent at the detector angle. At a low detector angle, however, the image has coherent features indicating the necessity of a simulation for individual systems.     

Analysis of main pigments and other ingredients in lac color product

The contents of the main pigments and other ingredients in commercial lac color products were determined by HPLC using an RP-18 column with 0.1 mol/L citric acid buffer solution-methanol (16:5) as the mobile phase, and a photodiode array (PDA) detector set at 280 nm and 490 nm. The main pigments were confirmed by PDA and electrospray ionization mass spectrometry. Laccaic acids A, B, C and E were detected in all lac color products, and the ratio of content of laccaic acid A in all products was over 50%. The total contents of laccaic acids A, B and C in lac color food additive products and reagent products were 775-858, 797 and 779 g/kg, respectively. As for the contents of ingredients except pigments in commercial food additive products, the maximum moisture content was about 10%, and ether-soluble substances amounted to 0.5-3.6%.     

自组织InAs/GaAs量子点的表面氮化研究

用低温光荧光(PL)和透射电子显微镜(TEM)研究了表面氮化自组织InAs/GaAs量子点的光学性能和微观结构。结果表明氮化后形成薄层的InAsN薄膜作为应变缓和层覆盖在量子点的表面,使得随着氮化时间的增加,InAs量子点的位错密度提高、尺寸变大、纵横比提高、发光波长变长、强度变低。