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Reduction of junction leakage currents is important to exactly obtain the energy distribution of gap states in hydrogenated amorphous silicon (a-Si:H) by post-transit photocurrent spectroscopy (PTPS). A double-layer transparent conducting gate composed of indium-tin-oxide (ITO) and silicon oxide (SiOx) is an effective means for this purpose in Schottky barrier sSBd diodes. However, there has been some concern that the presence of the SiOx layer could affect the PTPS results. We demonstrate from careful experimental studies that the insertion of the SiOx layer between ITO and a-Si:H does not give any additional structure in the energy distribution of gap states of a-Si:H measured by PTPS and the SB diodes with the ITO-SiOx double-layer gate are suited for exact PTPS measurements. [ABSTRACT FROM AUTHOR]

Post-transit photocurrent spectroscopy (PTPS) has been employed as an effective method to obtain the energy distribution of gap states in undoped hydrogenated amorphous silicon. In this article, we demonstrate that the simplifying assumptions in conventional PTPS related to the trap occupation are not always valid and special care should be taken when we extend PTPS to samples with larger leakage currents and/or high-defect densities. We show test diode structures and experimental conditions to exactly determine the energy distribution of both electron and hole trap states in these cases. The attempt-to-escape frequency, ν, both for electrons and holes has been evaluated from the temperature dependence of the characteristic points in PTPS signal. It has been found that the density of electron and hole trap states in the deeper energy range increases with long exposure to visible light while the density in the shallower energy range decreases, which suggests the occurrence of defect conversion. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Experimental studies have revealed that defect related properties in hydrogenated amorphous silicon (α-Si:H) can be modified by visible-light illumination during plasma enhanced chemical vapor deposition growth; light-induced degradation after growth and initial defect density has been reduced in the samples prepared under illumination with and without a shield mesh separating the plasma region and a substrate in the deposition chamber, respectively. These properties are metastable below the deposition temperature and are a result of the counterbalance between illumination and the thermal effects during growth. The reduction of the light-induced changes in the present samples does not relate to changes in hydrogen bonding. The defect annihilation reaction during growth has been enhanced and the reaction barrier has been lowered from 0.57 to 0.34 eV under illumination. It has also been found that the defect density depends exponentially on the intensity of incident visible light. [ABSTRACT FROM AUTHOR]

Studies the relationship between carrier diffusion lengths and defect density in undoped hydrogenated amorphous silicon. Small-signal lifetime measurement; Dependence of carrier diffusion lengths on defect density; Ratio of drift mobility of electrons to that of holes in a doped silicon under illumination.

Presents a study which performed experiments to characterize hydrogenated amorphous silicon (a-Si:H) prepared by alternatively repeating chemical-vapor deposition (CVD) from disilane and hydrogen plasma (HP) treatment. Details on the light-induced instability in a-Si:H; Details of an experiment on a-Si:H; Summary of structural and optoelectronic properties of CVD a-Si:H; Description of the energy distribution of deep defect states of a HP treated CVD a-Si:H.

Reports the experimental results of constant photocurrent method (CPM) studies on the deep defect states in a series of undoped a:silicon:hydrogen samples deposited at various temperatures. Samples and experiments; Analysis of CPM spectra; Experimental results and discussion; Conclusions.

Presents a study which investigated the properties of hydrogenated amorphous silicon prepared by glow discharge decomposition of silane with visible light illumination on a growing surface. Experimental details; Results and discussion; Conclusion.

Presents information on a study which investigated the electrical characterization of amorphous silicon (a-Si:H) using a liquid Schottky barrier. Advantages of using the surface photovoltage method using a liquid Schottky barrier; Properties of a-Si:H and crystalline (c) Si contacts with redox couple of quinone-hydroquinone; Application of capacitance-voltage measurements in liquid Schottky barrier diodes.

Abstract: Aim: Stomach contractions show two types of specific patterns in many species, that is migrating motor contraction (MMC) and postprandial contractions (PPCs), in the fasting and fed states respectively. We found gastric PPCs terminated with migrating strong contractions in humans, dogs and suncus. In this study, we reveal the detailed characteristics and physiological implications of these strong contractions of PPC. Methods: Human, suncus and canine gastric contractions were recorded with a motility‐monitoring ingestible capsule and a strain‐gauge force transducer. The response of motilin and ghrelin and its receptor antagonist on the contractions were studied by using free‐moving suncus. Results: Strong gastric contractions were observed at the end of a PPC in human, dog and suncus models, and we tentatively designated this contraction to be a postprandial giant contraction (PPGC). In the suncus, the PPGC showed the same property as those of a phase III contraction of MMC (PIII‐MMC) in the duration, motility index and response to motilin or ghrelin antagonist administration. Ghrelin antagonist administration in the latter half of the PPC (LH‐PPC) attenuated gastric contraction prolonged the duration of occurrence of PPGC, as found in PII‐MMC. Conclusion: It is thought that the first half of the PPC changed to PII‐MMC and then terminated with PIII‐MMC, suggesting that PPC consists of a digestive phase (the first half of the PPC) and a discharge phase (LH‐PPC) and that LH‐PPC is coincident with MMC. In this study, we propose a new approach for the understanding of postprandial contractions. [ABSTRACT FROM AUTHOR]

Background Rikkunshito ( RKT) is a gastroprotective herbal medicine. In this study, we investigated the role of RKT in the relaxation of the gastric body (fundus and corpus) and antrum. Methods We used Suncus murinus, a unique small model animal with similar gastrointestinal motility to humans and dogs. RKT was added at 0.1, 1.0, and 5.0 mg/mL to induce relaxation in vitro; the outcome measure was the intensity of relaxation. The number of spontaneous antral contractions in the absence or the presence of RKT was also counted. Key Results Rikkunshito induced the relaxation of the gastric body and antrum and decreased the number of spontaneous antral contractions in a dose-dependent manner. The responses to RKT (1.0 mg/mL) were not affected by pretreatment with atropine, N-nitro- l-arginine methyl ester, ritanserin, or ondansetron. On the other hand, timolol almost completely reversed the relaxation induced by RKT (1.0 mg/mL) on the gastric body and antrum and the occurrence of the spontaneous antral contractions. Both butoxamine, a β2-adrenoreceptor antagonist, and L 748337, a β3-adrenoreceptor antagonist, but not CGP 20712, a β1-adrenoreceptor antagonist, significantly reversed the RKT-induced (1.0 mg/mL) gastric relaxation. Conclusions & Inferences These results indicate that RKT stimulates and modulates gastric relaxation through β2- and β3-adrenergic, but not β1-adrenergic, pathways in S. murinus. [ABSTRACT FROM AUTHOR]

The subband-gap absorption current in a hydrogenated amorphous silicon film has been measured during plasma-enhanced chemical vapor deposition. The current is probed by a near-infrared laser while photoexcited carriers are generated under visible laser illumination. The trapped charge density is determined from the magnitude of current under the assumption of carrier generation and recombination kinetics. The result indicates that trapped charges are distributed uniformly in the film during growth, and they are reduced after the growth. The trapped charge density is minimized at a growth temperature of ≈473 K [ABSTRACT FROM AUTHOR]

Background It has been shown in human and canine studies that motilin, a gastroprokinetic hormone, induces gastric phase III contractions via the enteric nervous; however, the center of motilin action in the stomach has not been clearly revealed. In the present study, we investigated the neural pathway of motilin-induced gastric contraction by using Suncus murinus, a new animal model for motilin study. Methods An isolated suncus stomach was used in vitro to determine the mechanism of motilin action through the myenteric plexus. Synthetic suncus motilin (10−11-10−7 mol L−1) was added to an organ bath, and the spontaneous contraction response was expressed as a percent of ACh (10−5 mol L−1) responses. Motilin-induced contractions were also studied by a pharmacological method using several receptor antagonists and enzyme inhibitor. Key Results Suncus motilin induced a concentration-dependent gastric contraction at concentrations from 10−9 to 10−7 mol L−1. The responses to suncus motilin in the stomach were completely abolished by atropine and tetrodotoxin treatment and significantly suppressed by administration of hexamethonium, verapamil, phentolamine, yohimbine, ondansetron, and naloxone, whereas ritanserin, prazosin, timolol, and FK888 did not affect the action of motilin. Additionally, N-nitro l-arginine methylester slightly potentiated the contractions induced by motilin. Conclusions & Inferences The results indicate that motilin directly stimulates and modulates suncus gastric contraction through cholinergic, adrenergic, serotonergic, opioidergic, and NO neurons in the myenteric plexus. [ABSTRACT FROM AUTHOR]

A technique for achieving the in-cylinder stratification of external exhaust gas recirculation (EGR) gas in direct-injection (DI) diesel engines has been developed to reduce toxic exhaust emissions. The external EGR gas is supplied from one of the two intake ports which can create a swirl flow in either the upper or lower portion of the cylinder during the intake stroke. In the final stage of the compression stroke, a squish flow conveys the vertically stratified EGR gas into the piston cavity, generating a radially stratified EGR gas in the piston cavity at the end of the compression stroke. This strategy for achieving EGR gas stratification in the piston cavity was developed by using an unsteady computational fluid dynamics (CFD) code. Prior to the exhaust emission tests, the accuracy of the simulation was evaluated by planer laser-induced fluorescence (LIF) imaging. The exhaust emission tests showed that there was less smoke emission under medium load conditions when the EGR gas was delivered to the inner part of the piston cavity. The mechanism of this smoke reduction was investigated using CFD simulation, which is based on a series of calculations related to the internal flow of the injector nozzle, the in-cylinder fuel spray, and mixture formation and combustion. It has been shown that, at the beginning of the combustion, the higher concentration of EGR gas in the inner part of the cavity lowers the combustion temperature and reduces the soot formation rate. Air, which exists in the outer part of the cavity at the start of fuel injection, enhances the oxidation of the soot cloud in the piston cavity periphery in the latter half of the combustion period. [ABSTRACT FROM AUTHOR]

Thyroid-stimulating hormone (TSH)-producing cells (TSH cells), which account for a large fraction of the cells in the rat pars tuberalis (PT), have been found to express MT1 melatonin receptor and mammalian clock genes at high densities. Although these findings suggest that TSH production in the rat PT is regulated by melatonin and/or the biological clock, there have been no studies focusing on the diurnal change and regulation mechanism of TSH production in the rat PT. Therefore, in the present study, we examined diurnal changes of in TSHβ and α-glycoprotein subunit (αGSU) mRNA expression and TSH immunoreactivity (-ir) in the rat PT, and also examined the relationship between melatonin and TSH production in vivo. Both TSHβ mRNA expression and αGSU mRNA expression in the PT showed diurnal variations: the expression levels were lowest at the light phase [Zeitgeber time (ZT)4] and high at the dark phase (ZT12 and ZT20). TSH-ir in the PT showed the lowest level at ZT4, as was found for mRNA expression. Interestingly, TSH-ir, which was confined to the Golgi apparatus at ZT4, spread to the cytoplasm, and most of the TSH cells in the PT were uniformly immunostained in the cytoplasm at ZT20. Despite the fact that chronic administration of melatonin suppressed TSHβ and αGSU mRNA expression, TSH-ir in the PT was significantly enhanced. These findings results clearly show that there are diurnal changes in TSH expression and accumulation in rat PT-TSH cells and suggest that these fluctuations are regulated by melatonin. [ABSTRACT FROM AUTHOR]

A new technique based on phosphor thermometry for measurements of two-dimensional gas-phase temperature, was examined as a new laser diagnostic. Calibration of Dy:YAG phosphor was carried out on the surface of a solid. The data were applicable for gas thermometry since the validation of the line intensity ratios method, showed good agreement with both the lifetime method and thermocouple data in a steady gas flow. Single-shot phosphor thermometry was examined in turbulent combustion in an engine. A reasonable temperature deviation and agreement with calculated data to within 5% precision was achieved in the ignition process of a compression ignition engine. Influencing factors such as chemical luminescence and intrusion into the combustion have also been discussed. [ABSTRACT FROM AUTHOR]

Background Photodynamic therapy (PDT) is available for the treatment of various skin tumours and other skin diseases. Ultraviolet (UV) irradiation induces DNA damage, cyclobutane pyrimidine dimers (CPD) (6-4) photoproducts (6-4PP) and 8-hydroxy-2′-deoxyguanosine (8-OHdG), all of which are carcinogenic for the skin. However, effects of PDT on DNA damage and carcinogenesis are unclear. Objectives To compare the production of photoproducts and the induction of skin tumours in mouse epidermis treated with UVB or PDT. Methods We performed UVB irradiation or ATX-S10(Na)–PDT on the skin of 20 hairless mice, in each case, and analysed DNA damage and tumour induction. Results After a single irradiation of UVB on mouse skin, CPD, 6-4PP and 8-OHdG were detected in the nuclei of keratinocytes. In contrast, PDT-treated mouse keratinocytes showed induction of 8-OHdG, but not of CPD or 6-4PP. Skin tumours induced by UVB irradiation (3 kJ m−2 three times weekly) were observed following 15 weeks of irradiation (mean ± SEM tumour incidence 3·2 ± 1·8%; tumour number 3·2 ± 1·6 per mouse) and increased depending on irradiation times and doses. Following 30 weeks of UVB irradiation (3 kJ m−2 three times weekly), mean ± SEM tumour incidence and tumour number were 28·7 ± 4·8% and 14·2 ± 2·8% per mouse, respectively. Although skin tumours were also detected in PDT-treated mouse skin following 80 weeks of treatment (mean ± SEM tumour incidence 9·1 ± 1·8%; tumour number 12·2 ± 2·3 per mouse), the number of tumours was not statistically different from untreated mouse skin (mean ± SEM tumour incidence 4·1 ± 3·8%; tumour number 5·2 ± 3·3 per mouse). Conclusions PDT induced 8-OHDG but not CPD or 6-4PP, and was shown to be a relatively safe modality following multiple applications to mouse skin. [ABSTRACT FROM AUTHOR]

The purpose of the study is to evaluate the tumour enhancing characteristics and biodistribution of a newly developed metalloporphyrin derivative, HOP-9P (13, 17-bis (1-carboxypropionyl) carbamoylethyl-3, 8-bis (1-phenylpropyloxyethyl)-2,7,12,18-tetramethyl-porphynato manganese (III)). Seven mice bearing SCC VII tumours were imaged using T1-weighted conventional spin echo magnetic resonance images before and 5 min, 2 h and 24 h after intravenous injection of 0.1 mmol/kg of HOP-9P. For the acquired images, signal intensities of the tumour, muscle and oil-phantom were measured. Then, tumor/oil and tumor/muscle signal intensity ratios were calculated. Nineteen mice were sacrificed before or after the administration of HOP-9P (at 5 min, 2 h and 24 h), and the biodistribution of manganese in the tumour, muscle, liver, blood and kidneys was measured using optical emission spectrometers and was expressed as micrograms of manganese per gram of tissue. The tumour/muscle signal intensity ratio at 24 h (3.18 ± 0.34) was significantly higher than precontrast ratio (1.77 ± 0.20) (P < 0.05). The biodistribution assessment of manganese demonstrated that HOP-9P gradually and consistently accumulated in the tumour to reach the highest concentration at 24 h (3.49 ± 1.22 μ gMn/g). It is concluded that HOP-9P is a potential tumour-specific MR contrast agent. [ABSTRACT FROM AUTHOR]