Investigation of interfacial instabilities with a two-layer slide coating process

Organic electronics have been thoroughly investigated due to their broad application potential, ranging from light-emitting diodes to photovoltaics. The processing of organic electronics is trending from vacuum toward wet chemical deposition, which allows fast low-cost mass production of devices with scalable dimension. One of the current challenges of wet film processing is the redissolution of already dried active materials when applying a liquid top layer. Further, increasing overall process efficiency by coating multiple liquid layers in one step raises such challenges as liquid–liquid mixing or dewetting. This article describes the experimental investigation of these instabilities for two-layer flows with organic solvents. A modified slide coating device was chosen where an extended plate after the slot exit allows prolonged observation of the flow while it travels down the plate. During experimentation, stable and unstable two-layer flows as well as different types of instabilities were detected. The key finding is a correlation of flow stability with the spreading coefficient, a combined measure of surface and interfacial tensions. Focusing on fluid properties, this paper succeeds in defining a three-dimensional stability window for a dual-layer flow.     

Accelerated aromatic compounds degradation in aquatic environment by use of interaction between Spirodela polyrrhiza and bacteria in its rhizosphere

Accelerated degradation of organic chemicals by aquatic plant-bacterial associations was reported for the first time with elucidation of the role and contribution of aquatic plant and bacteria in its rhizosphere using a fast-growing giant duckweed, Spirodela polyrrhiza. The results clearly showed the accelerated degradation of all the three aromatic compounds (phenol, aniline and 2,4-dichlorophenol [2,4-DCP]) tested by aquatic plant-bacterial associations. In phenol degradation system, phenol-degrading bacteria indigenous to the rhizosphere fraction of S. polyrrhiza mainly contributed, while in aniline degradation system S. polyrrhiza mainly contributed by stimulating aniline-degrading bacteria both in the rhizosphere and balk water fraction. On the other hand in 2,4-DCP degradation system, S. polyrrhiza itself mainly contributed to its removal by uptake and degradation. Thus, the mechanisms for accelerated removal of aromatic compounds were quite different depending on the substrates. S. polyrrhiza showed selective accumulation of phenol-degrading bacteria in its rhizosphere fraction, while aniline- and 2,4-DCP-degrading bacteria were not much accumulated. S. polyrrhiza secreted peroxidase and laccase. However, both of the enzymatic activities increased with the addition of aromatic compounds, degrading ability of S. polyrrhiza itself should be owing to the production of peroxidase rather than laccase because the change of peroxidase activity and concentration of each aromatic compound well concurred. From the results obtained in the present study, it can be concluded that the feasibility of the use of aquatic plant-bacterial associations to accelerate the degradation of organic chemicals especially recalcitrant compounds in aquatic environment was shown.     

Vitamin C supplementation alleviates electroshock stress but not restraint stress in ICR mice

The aim of this study was to investigate what kind of stress vitamin C could alleviate. Experiments were performed using male ICR mice. Vitamin C (1, 5, 25, and 100 mg/kg) was administered orally daily for 7 days without stress and then were given for 5 days with electroshock (ES) or restraint stress (RS). After loading final stress, we recorded stress-related behaviors and measured the levels of blood corticosterone. Vitamin C supplementation (25 and 100 mg/kg) partially blocked stress-related behaviors such as freezing, smelling, burrowing, facewashing, and grooming. It decreased also staying time in closed arms. Stress responses induced by ES but not immobility were also significantly alleviated by vitamin C. Vitamin C (25 and 100 mg/kg) decreased corticosterone level increased by ES. Swimming time in cold water (8±2°C) was not changed by vitamin C, but crossing frequency in the electric field was increased by vitamin C (25 mg/kg). These results suggest that vitamin C supplementation can prevent damages or diseases induced by stress, especially psychological stress.     

Evaluation of danger from fermentation-induced spontaneous ignition of wood chips

Recently we conducted investigations in biological wastes because large pile-up storage of waste wood chips and others caused many fires in Japan. This paper shows the experimental results on wood chips with thermal analysis, by using a Thermogravimetry-differential thermal analysis (TG-DTA) and micro calorimeters, and as well with spontaneous ignition measurements, such as a UN wire mesh cube tester and a spontaneous ignition tester (SIT). Exothermic reaction of wood chips was observed during 45-60 degrees C only by the high sensitive microcalorimeters, TAM and MS 80. This reaction is far apart from the second major reaction by oxidation and is not easy to be recognized by the conventional detectors, like the TG-DTA and the wire mesh cube tester, because their sensitivity cannot meet the strict requirement. Correspondingly, experimental results under the adiabatic condition in the SIT confirmed this theory, in which the onset temperature of spontaneous ignition of wood chips was measured as 50-80 degrees C. This implies that the weak initial reaction at ambient temperatures mainly results from microbial fermentation in the presence of its inherent moisture and possibly gives rise to the further intense combustion sustained by a chemical reaction if the heat cannot be removed from the large scale storage of wood chips.     

Removal of arsenic from contaminated soils by microbial reduction of arsenate and quinone

We investigated bioremediation of As-contaminated soils by reductive dissolution of As using a dissimilatory As(V)-reducing bacterium (DARB), Bacillus selenatarsenatis SF-1. We also examined the effect of anthraquinone-2,6-disulfonate (AQDS), an extracellular electron-shuttling quinone, on the As extraction. When B. selenatarsenatis was incubated with As(V)-laden Al precipitates, no acceleration of As dissolution was observed in the presence of AQDS, even though the microbial reduction of AQDS occurred actively. In contrast, AQDS addition significantly enhanced the reductive dissolution of As and Fe in analogous experiments with As(V)-laden Fe(III) precipitates, whereas As dissolution did not occur in the absence of the As(V) reducer. These results indicate the dissolution of As was accelerated by indirect reduction of solid-phase Fe(III) following microbial AQDS reduction, although As(V) reduction is vital for As extraction. B. selenatarsenatis was able to extract As from two types of industrially contaminated soils through reduction of solid-phase As(V) and Fe(III). The copresence of AQDS with B. selenatarsenatis improved the removal efficiency of As from the contaminated soils, concomitantly releasing Fe(II), suggesting that simultaneous use of DARB and electron-shuttling compounds can be an effective strategy for remediation of As-contaminated soils.     

An assumed displacement hybrid finite element model for linear fracture mechanics

This paper deals with a procedure to calculate the elastic stress intensity factors for arbitrary-shaped cracks in plane stress and plane strain problems. An assumed displacement hybrid finite element model is employed wherein the unknowns in the final algebraic system of equations are the nodal displacements and the elastic stress intensity factors. Special elements, which contain proper singular displacement and stress fields, are used in a fixed region near the crack tip; and the interelement displacement compatibility is satisfied through the use of a Lagrangean multiplier technique. Numerical examples presented include: central as well as edge cracks in tension plates and a quarter-circular crack in a tension plate. Excellent correlations were obtained with available solutions in all the cases. A discussion on the convergence of the present solution is also included.     

Arsenic extraction from solid phase using a dissimilatory arsenate-reducing bacterium

We investigated the feasibility of a novel bioremedial strategy for arsenic-contaminated soil using a dissimilatory arsenate-reducing bacterium (DARB), Bacillus sp. SF-1. SF-1 was able to effectively extract arsenic from various arsenic-laden solids, via the reduction of solid-phase arsenate to arsenite, which is much less adsorptive than arsenate. The strain can be an easy-to-handle, and cost-effective bioremedial agent.     

ICAM-1-expressing pocket epithelium, LFA-1-expressing T cells in gingival tissue and gingival crevicular fluid as features characterizing inflammatory cell invasion and exudation in adult periodontitis

Activated T lymphocytes constitute a major component of inflammatory cells in the early periodontal lesion, and also appear in the gingival crevicular fluid. In an attempt to clarify the relationship between the ICAM-1 (CD54) expression of pocket epithelium in gingiva and the infiltrating lymphocyte population, we carried out an analysis of CD11a+(LFA-1 alpha), CD25+(IL-2R alpha) and CD4+(Th) cells subjacent to ICAM-1-expressing pocket epithelia and CD11a+CD25+CD4+ cells in gingival crevicular fluid (GCF). GCF was collected by crevicular washing from 16 patients with periodontitis (P group) and 3 subjects with healthy gingiva (H group). Peripheral blood (PB) was collected at the same time. Mononuclear cells were isolated by Ficoll-paque gradient centrifugation from GCF and PB. Monoclonal antibodies (mAb) to CD11a, CD25, and CD4 were used for three-color flow cytometry. Gingival biopsies were obtained from 7 patients in P group and 3 subjects in H group. Serial cryostat sections (6 microns in thickness) were prepared from each biopsy, on which a double staining was performed. The number of CD11a+CD25+CD4+ cells and the fluorescence intensity of FITC conjugated anti-CD11a were significantly higher in GCF than in PB (p < 0.001 to p < 0.01). CD11a+CD25+CD4+ cells were not detected in GCF in H group. The pocket epithelia expressed CD54 in P group, but not in H group. The number of CD11a+, CD25+ and CD4+ cells infiltrating the connective tissue subjacent to the upper, middle and lower parts of the CD54 positive pocket epithelium (n = 16) was 141 +/- 26, 38 +/- 13, 144 +/- 29 (cells/0.04 mm2), respectively, whereas in the CD54 negative pocket epithelium, it was (n = 5) 9 +/- 2, 3 +/- 1, 8 +/- 3. In P group, the CD11a+CD25+CD4+ cell number in GCF correlated with CD25+, CD11a+ cells in the connective tissue subjacent to the CD54+ pocket epithelium. These results indicate that expression of ICAM-1 in pocket epithelium is relevant to the migration of CD11a, CD25, CD4 positive cells in connective tissue subjacent to the pocket epithelium into the periodontal pocket. Assessing the relationship of our findings and other adhesion molecules would offer important clues to the understanding of T cell migration in affected gingiva.     

Effects of trace impurities on the adherence of oxide to ultra low carbon steel

The effects of trace impurities on the adherence of oxides to ultra low carbon steels were investigated. Three steels, of differing chromium, aluminium, silicon, nitrogen and oxygen content, were oxidized at 850 K in 10% CO₂-90% N₂ gas and then oxidized at 770 K in 10% CO₂-10% O₂-80% N₂ gas. Surface analysers, i.e. a Mössbauer spectrometer, Auger electron spectrometer and/or ion micro analyser, were utilized in the present study because of the very thin layer of oxides formed (1.0 to 2.0 µm). The following results were obtained. The oxide on the Al-containing steel spalled at the outer-inner oxide interface, where aluminium was enriched and many cavities appeared. The inner oxide layer, oxidized by the transport of CO₂ or O₂ gases along the outer layer grain boundaries or micropores, became thick. This generated a stress at the outer-inner layer interface with the resultant formation of cavities. On the other hand, the oxide on the Cr-containing steel showed good adherence to the metal. The inner layer, enriched with chromium, did not become thick and had no cavities at the interface. The addition of chromium to the Al-containing steel resulted in good oxide adherence because chromium acted as a barrier to the aluminium enrichment.     

Analysis of high-power factor AC-DC boost converter

This paper presents analysis of a high-power factor ac-dc converter with a boost converter operating in the discontinuous conduction mode (DCM) and the critical conduction mode (CRM). The converter can be expressed by a nonlinear differential equation for each mode. The equation in DCM is solved analytically by separating its variable (output voltage) into two terms of a ripple component and a direct component, and by linearizing the equation for the ripple component. On the other hand, the equation in CRM can be solved analytically. Furthermore, the source current waveform of the converter is expanded into the Fourier series. As a result, the output voltage, its ripple and the power factor of the converter in DCM and CRM are derived as a function of the circuit parameters, respectively, and verified experimentally. These equations exhibit clearly the effect of each circuit parameter of the converter and the difference between the converter in DCM and in CRM. The converter operating in CRM produces sinusoidal ac current with unity power factor.