Improvement of the photostability for YVO4:Bi,Eu nanoparticles synthesized by the citrate route

YVO₄:Bi³⁺,Eu³⁺ nanophosphor synthesized by the citrate route shows the photobleaching behavior, i.e., the decrease in photoluminescence intensity under the continuous irradiation of excitation light. This photobleaching property is remarkably suppressed by the washing post-treatment combined with centrifugation and the hydrothermal post-treatment. A relation between the fraction of photobleach and the amount of citrate ions coordinating to metallic ions at the surface of nanoparticles verifies that the photobleaching behavior of YVO₄:Bi³⁺,Eu³⁺ nanophosphor originates from the redox reaction between the citrate ions and V⁵⁺ in YVO₄ host crystal. The long-term light fastness test reveals that the hydrothermally treated YVO₄:Bi³⁺,Eu³⁺ nanophosphor has sufficient photostability for practical use over 15 years outside.     

Selective and in-situ determination of carbonate and oxide particles in aqueous solution using laser-induced breakdown spectroscopy (LIBS) for wearable information equipment

Laser-induced breakdown spectroscopy (LIBS) has been applied for quantitative analysis of Al₂O₃, CaCO₃ and MgO particles suspended in water. In the single elemental system, the plasma emission intensities of Al, Ca and Mg were linearly increased with concentration of elements in the range of 1.0×10^?5–1.0×10^?3  M, 1.0×10^?4–2.0×10^?3 M and 8.0×10^?5 –4.0×10^?3 M, respectively. We also investigated the concentration dependence of breakdown spectra for suspended mixtures of Al₂O₃, CaCO₃ and MgO particles. The emission lines, such as Al I, Ca I, Ca II and Mg I, were appeared in the LIBS spectrum simultaneously, and each emission peak could be deconvoluted. The plasma emission intensities of Al, Ca and Mg in the multielemental system were also linearly increased with their concentrations in the range of 1.0×10^?5–1.0×10^?3 M, 1.0×10^?4–2.0×10^?3 M and 4.0×10^?4–2.0×10^?3 M, respectively. LIBS was found to be available for quantitative and qualitative measurement of the concentrations of Al₂O₃, CaCO₃ and MgO particles suspended in water. The present results suggest that LIBS is a potentially useful tool for in-situ analysis on particles composition and concentrations for environmental monitoring by the wearable information equipments.     

Water mist formation in vapor-mist dielectrics and its effect

It has been proposed that vapor-mist dielectrics in which mixing liquid droplets such as tetrachloroethlene in a gas have the ability of increasing flashover, impulse voltage, and of suppressing partial discharge. Vapor-mist methods have been performed on other materials and the effect of the mist can also be obtained on benzene, hexane, and even water as general materials. Although these studies have been carried out, neither the discharge mechanism on vapor-mist nor the reason for the increase of the discharge voltage is understood fully because the mist is of various sizes. On the other hand, agglomeration of water molecules can be studied with the FR-IR method, and are classified into monomer, dimer, trimer (including polymer). Water gives mist stats which are significant in discussing effects. This paper describes states of water mist and their effect under nonuniform field with positive and negative polarities. Water mist in vapor exists as dimer and trimer, and their amount decreases with the reduction of temperature. These mists have no effect on discharge suppression. However, when the mists are formed by space charges, the inception voltage is increased by these mists in the negative polarity.     

Prediction of the capacity of a heat exchanger by a thermal network method: Modified effective specific heat model considering the influence of static pressure distributions of refrigerants

In this paper, we proposed a method to predict the capacity of a heat exchanger by considering static pressure distributions of refrigerants. The thermal network method was modified by adding an equivalent heat generation term into a heat balance equation that was connected with calculated 1D static pressure distributions of refrigerants. An experiment was performed with a heat exchanger having two rows and two passes to verify the accuracy of the proposed method. The result showed the error of the predicted capacity to be less than 1% for an evaporator and less than 2% for a condenser. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(5): 376–390, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10039     

Recursion Schemata for Slowly Growing Depth Circuit Classes

We characterize iterated log depth circuit classes between AC⁰ and AC¹ by Cobham-like bounded recursion schemata. We also give alternative characterizations which utilize the safe recursion method developed by Bellantoni and Cook.     

Occurrence,horizontal transfer and degeneration of VDE intein family in Saccharomycete yeasts

VDE is a homing endonuclease gene originally discovered as an intervening element in VMA1s of Saccharomyces cerevisiae. There have been two independent subfamilies of VDE, one from S. cerevisiae strain X2180-1A and the other from Saccharomyces sp. DH1-1A in the host VMA1 gene, and they share the identity of 96.3%. In order to search the occurrence, intra/interspecies transfer and molecular degeneration of VDE, complete sequences of VMA1 in 10 strains of S. cerevisiae, eight species of saccharomycete yeasts, Candida glabrata and Kluyveromyces lactis were determined. We found that six of 10 S. cerevisiae strains contain VDEs 99.7-100% identical to that of the strain X2180-1A, one has no VDE, whereas the other three harbour VDEs 100% identical to that of the strain DH1-1A. S. carlsbergensis has two VMA1s, one being 99.8% identical to that of the strain X2180-1A with VDE 100% identical to that of the strain DH1-1A and the other containing the same VMA1 in S. pastorianus with no VDE. This and other evidence indicates that intra/interspecies transmissions of VDEs have occurred among saccharomycete yeasts. Phylogenetic analyses of VMA1 and VDE suggest that the S. cerevisiae VDEs had branched earlier than other VDEs from an ancestral VDE and had invaded into the host loci as relatively late events. The two VDEs seemed to degenerate in individual host loci, retaining their splicing capacity intact. The degeneration of the endonuclease domains was distinct and, if compared, its apparent rate was much faster than that of the protein-splicing domains.     

Near-infrared spectroscopic monitoring of the diffusion process of deuterium-labeled molecules in wood. Part I: softwood

The diffusion process of several molecules (D2O, n-butanol (OD) and t-butanol (OD)) in softwood (Sitka spruce) was investigated by means of a deuterium exchange method and Fourier transform near-infrared (FT-NIR) polarization spectroscopy. The location of OH groups in different states of order of cellulose in wood was clarified by analyzing the FT-NIR transmission spectra ranging from 7200 to 6000 cm(-1). Four absorption bands were assigned to 2 x v(OH) absorptions of the amorphous regions, OH groups in semi-crystalline regions, and two types of intramolecular hydrogen-bonded OH groups in the crystalline regions, respectively. The saturation level of accessibility was very different for these absorption bands (i.e., 70-80, 60, and 40-50% for the amorphous, semi-crystalline, and crystalline regions, respectively). However, the saturation accessibilities for each absorption band varied little with molecular structure and geometry of the diffusants. The diffusion rate of D2O was much faster than that of n-butanol (OD) and t-butanol (OD) for all states of orders. The size effect of the butanols led to slight differences in the diffusive transport in the crystalline regions.     

Structural change of water with solutes and temperature up to 100 degrees C in aqueous solutions as revealed by attenuated total reflectance infrared spectroscopy

The attenuated total reflectance infrared (ATR-IR) spectra of several aqueous solutions have been measured by using a newly developed heatable rod-type ATR cell. The OH stretching bands showed systematic change with increasing solute concentrations and these changes can be explained by four different OH components based on curve-fitting results. NaCl solutions show longer H-bond distance character, while carbonate solutions present shorter ones. The Na2CO3 1 M solution conserves this shorter H-bond nature up to 100 degrees C. On the other hand, the loose nature of NaCl solutions becomes less pronounced at higher temperatures because of the dissociation of pure water clusters. These in situ observations of water structures are generally in agreement with the expected nature of fluids within the earth.     

Cytochemistry of gastric parietal cells with high-pressure freezing followed by freeze-substitution

Gastric parietal cells were examined for changes in their ultrastructure and distribution of the proton pump during feeding and fasting states in rats. The fundic glands from rats fed ad libitum or fasted with free access to water were cryofixed using high-pressure freezing followed by freeze-substitution in acetone containing osmium or acrolein and then embedded in Epon 812 or Lowicryl K4M resin, respectively. Excellent ultrastructural preservation was achieved. During the feeding state, intracellular canaliculi and numerous microvilli were well developed, while tubulovesicles were poorly developed. In contrast, during the fasting state, the microvilli in the narrowed space of the intracellular canaliculi were tightly packed and the tubulovesicles were enlarged. Ultrathin sections were immunostained with antibodies against the alpha- and beta-subunits of the proton pump, H+ x K(+)-ATPase, using the immunogold method. The labelling was strong and clearly localized in comparison with that obtained using the conventional chemical-fixation method. Each subunit was localized on the membrane of the microvilli, intracellular canaliculi and tubulovesicles. The distribution of subunit proteins varied between the two states. During ad libitum feeding, the immunolabelling was localized strongly on the membranes of the microvilli and intracellular canaliculi. In contrast, the labelling was strong on the tubulovesicle membrane in the fasting state. The results obtained with each anti-subunit antibody by H+ x K(+)-ATPase immunostaining revealed differences in distribution and labelling density between the feeding and fasting states.     

Dynamic flying characteristics of an air bearing slider over a disk with grooves and distribution of material properties

Bit-patterned media (BPM) consisting of land parts for read/writing and grooves, which are almost filled with non-magnetic materials to prevent magnetic interference between recording bits, are considered to be promising media for achieving ultrahigh density recording. A flying head slider flying over a BPM disk suffers from variations in both the spacing and van der Waals (vdW) attractive forces, which induce slider vibrations and spacing fluctuations. In the present study, we considered that BPM disks not only have a groove depth distribution, but that they also have a distribution of material properties (e.g., refractive index), which gives rise to a distribution in the vdW force. In the dynamic responses of sliders with small groove depths and a small variation in the refractive index, spacing fluctuations are found to be a superposition of fluctuations due to slider behaviors (1) over a disk with transverse grooves in a uniform material with a uniform refractive index (Case 1) and (2) over a flat disk with a refractive index distribution (Case 2). When the effects of Cases 1 and 2 cancel each other, the spacing fluctuations for the two cases cancel each other, reducing the total spacing fluctuation.