Dark Current Characteristics of a Radiation Detector Array Developed Using MOVPE-Grown Thick CdTe Layers on Si Substrate

We present reverse bias current (dark current) characteristics of a two-dimensional monolithic pixel-type nuclear radiation detector array fabricated using metalorganic vapor-phase epitaxy (MOVPE)-grown thick CdTe epitaxial layers on Si substrate. The (14?×?8) pixel array was formed by cutting deep vertical trenches using a dicing saw, where each pixel possesses a p-CdTe/ n-CdTe/n ⁺-Si heterojunction diode structure. The dark currents showed pixel-to-pixel variations when measured at higher applied biases exceeding 100?V. The dark current had a dependence on the pixel thickness, where pixels with lower CdTe thickness exhibited higher currents. Moreover, the temperature dependence of the dark current revealed that a deep level with activation energy of around 0.6?eV is responsible for the observed dark currents and their pixel-to-pixel variation. We discuss that the effective ratio of Te to Cd at the growth surface is a major factor that controls the thickness variation, and is also responsible for the formation of 0.6?eV deep levels.     

Simplified preparation of crude and functional coagulogen by thermal inactivation of serine proteases in Limulus amebocyte lysate and its application for rapid endotoxin determination

The effects of thermal treatment on Limulus amebocyte lysate (LAL) reagent were studied. Thermal resistances of enzymes and coagulogen in LAL reagent were evaluated by aggregometry and SDS-PAGE. Although enzyme activities of LAL reagent were completely lost after heating at temperatures above 60 °C for 10 min, gelating activities of coagulogen were retained even over 80 °C. Phenylmethanesulfonyl fluoride (PMSF; 1 mmol/mL), a strong non-specific serine-protease inhibitor, did not completely inactivate serine-protease activities of LAL. As a result, complete hydrolysis of coagulogen to coagulin was unexpectedly obtained. Solvent treatment of LAL was similar in effect to thermal treatment of LAL, but there were 2 problems: complete removal of solvent from samples and increased solution turbidity during preparation. To study the application of thermal-treated LAL, we conjugated it with titania particles. LAL-conjugated titania particles were obtained as small aggregates between titania nanoparticles and thermal-treated LAL (LAL-conjugated microbeads; LCM). When the mixture of LCMs and fresh LAL reagent was reacted with endotoxin an acute aggregation of LCMs was induced prior to the aggregate formation of LAL as monitored by stirring turbidimetry. This method, endotoxin microbeads aggregometry (EMA) may provide a rapid and sensitive method for endotoxin determination.     

Dietary Guar Gum Reduces Lymph Flow and Diminishes Lipid Transport in Thoracic Duct-Cannulated Rats

Guar gum has a well-recognized hypolipidemic effect. This effect is thought to be due to the physicochemical properties of guar gum, which may cause changes in adsorption of lipids or the viscosity of the intestinal contents. Guar gum is a non-specific absorption inhibitor of any type of lipid-soluble compound. Permanent lymph duct cannulation was performed on rats to investigate the effects of dietary guar gum on lymph flow and lipid transport. Rats fed a 5% guar gum diet were compared with those fed a 5% cellulose diet, and lymph was collected after feeding. The water-holding capacity (WHC), settling volume in water (SV), and viscosity of guar gum were compared with those of cellulose. Rats fed with the guar gum diet had significantly lower lymph flow and lymphatic lipid transport than did rats fed with the cellulose diet. The WHC, SV, and viscosity of guar gum were significantly higher than those of cellulose. We propose that dietary guar gum reduces lymph flow and thereby diminishes lipid transport by means of its physicochemical properties related to water behavior in the intestine.     

Signal flow graph modelling and analysis of interleaved DC?DC parallel converters

This paper presents a systematic development of a unified signal flow graph model for an interleaved DC–DC parallel converter system operating in continuous current mode. This signal flow graph approach provides a means to translate directly the switching converter to its graphic model, from which the steady-state and dynamic behaviour of the converter can be studied easily. The development of a unified signal flow graph is explained for a three-cell interleaved parallel converter system. Derivation of large-signal, small-signal and steady-state models from a unified signal flow graph is demonstrated by considering a two-cell interleaved converter system operating in complementary activation mode. Converter performance expressions such as steady-state voltage gain, efficiency expressions and small-signal characteristic transfer functions are also derived. A large-signal model was programmed in a TUTSIM simulator, and the large-signal responses against supply and load disturbances were predicted. Signal flow graph analysis results are validated with PSIM simulations. Experimental observations are provided to validate the signal flow graph modelling method. Further, the mathematical models obtained from the signal flow graph modelling are in agreement with those obtained from the state-space averaging technique.     

Optimization of magnet arrangement in double‐layer interior permanent‐magnet motors

The arrangement of permanent magnets in double‐layer interior permanent‐magnet motors is optimized for variable‐speed applications. First, the arrangement of magnets is decided by automatic optimization. Next, the superiority of the optimized motor is discussed by considering d‐ and q‐axis equivalent circuits that take into account the magnetic saturation of the rotor core. Finally, experimental veri?cation is carried out with a prototype motor. It is con?rmed that the maximum torque of the optimized motor under both low‐speed and high‐speed conditions is higher than that of conventional motors because of the relatively large q‐axis inductance and small d‐axis inductance. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(4): 54–63, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22348     

Next Day Peak Load Forecasting Using Neural Network With Adaptive Learning Algorithm Based On Similarity

In this article we propose the adaptive learning algorithm of neural network with respect to a rapid temperature change of forecasted day. The proposed adaptive learning algorithm is used to shift the learning range of previous year of forecasted day. Therefore, the proposed neural network can be trained by using learning data, including the maximum temperature to be forecasted. The suitability of the proposed approach is illustrated through an application to actual load data of Okinawa Electric Power Company in Japan.     

The Effects of Conventional Stabilizers and Phenol Compounds Used as Antioxidants on the Stabilization of Nitrocellulose

The thermal behavior of nitrocellulose (NC) containing diphenylamine (DPA), 2‐nitrodiphenylamine (2‐NO₂‐DPA), N‐nitrosodiphenylamine (N‐NO‐DPA), ethyl centralite (EC), akardite II (AKII), 1,1,3‐tri‐(2‐methyl‐4‐hydroxy‐5‐tert‐butyl‐phenyl)‐butane (BP_less), 3‐(3,5‐di‐tert‐butyl‐4‐hydroxy‐phenyl)‐propionic acid octadecyl ester (BP_hin), and 3‐(3‐tert‐butyl‐4‐hydroxy‐5‐methyl‐phenyl)‐propionic acid 2‐(9‐{2‐[3‐(3‐tert‐butyl‐4‐hydroxy‐5‐methyl‐phenyl)‐propionyloxy]‐1,1‐dimethyl‐ethyl}‐2,4,8,10‐tetraoxa‐spiro [5.5] undec‐3‐yl)‐2‐methyl‐propyl ester (BP_semi) was observed during isothermal storage at 393 K using a C80 microcalorimeter. The results indicate that each stabilizer decreased NC's maximum heat release rate and increased the induction period of heat release. We also observed that the maximum heat release rate and the induction period were dependent on the amount of stabilizer. DPA decreased the maximum heat release rate to the greatest extent, with the other stabilizers having similar effects on the decrease of maximum heat release rate. AKII prolonged the induction period of heat release most. The order of prolongation of the induction period was AKII>2‐NO₂‐DPA≈DPA>N‐NO‐DPA≈EC>BP_less≈BP_semi≈BP_hin.     

Effects of dietary defatted squid on cholesterol metabolism and hepatic lipogenesis in rats

Male Sprague-Dawley rats were fed a cholesterol-free (Exp. 1) or cholesterol-supplemented (Exp. 2) diet containing 20% casein (control group) or 15% defatted squid and 5% casein (defatted squid group), as protein, for 14 d. Serum and hepatic cholesterol concentrations were lower in rats fed defatted squid than in those fed casein in both cholesterol-free (−20%, P<0.05 and −15%, P<0.05, respectively) and cholesterol-supplemented (−25%, P<0.05 and −15%, P<0.05, respectively) diets. Hepatic triglyceride concentration was lower in the defatted squid than in the control groups in both cholesterol-free (−51%, P<0.05) and cholesterol-supplemented diets (−38%, P<0.01). The activities of cytosolic fatty acid synthase and the NADPH-generating enzymes, malic enzyme and glucose-6-phosphate dehydrogenase, in the liver were lower in the defatted squid than in the control groups in both cholesterol-free (−21%, P<0.01, −33%, P<0.05, and −33%, P<0.01, respectively) and cholesterol-supplemented diets (−34%, P<0.05, −57%, P<0.05, and −67%, P<0.05, respectively). The activity of mitochondrial carnitine palmitoyltransferase in the liver was comparable between the control and defatted squid groups. The activity of Mg²⁺-dependent phosphatidate phosphohydrolase in the liver cytosol was lower in the defatted squid (−9%, P<0.05) than in the control groups only in the cholesterol-free diet. Fecal excretion of total steroids was stimulated by the feeding of defatted squid in both cholesterol-free (+77%, P<0.005) and cholesterol-supplemented diets (+29%, P<0.01). These results suggest that the nonlipid fraction of squid exerts a hypocholesterolemic effect by increasing the excretion of total steroids in feces. The fraction also induces a triglyceride-lowering activity in the liver by decreasing hepatic lipogenesis.     

Am1 MO Study of Benzene Nitro Derivatives

Molecular properties of benzene nitro derivatives were investigated by using semi-empirical MO calculations. As the results, the molecular structures and the rotational barrier of the nitro group calculated by AM1 showed a good agreement with the experimental values. The heats of formation in gaseous and condensed phases were obtained by considering isodesmic reactions. By this procedure, the heat of formation of hexanitrobenzene in solid phase was calculated to be +22.7 kcal/mol. The detonation parameters were also calculated by using four equations of state. The predicted detonation velocities showed a good agreement with the experimental values.