Showing papers by "Nagoya Institute of Technology published in 2006"

Nutraceutical Effects of Branched-Chain Amino Acids on Skeletal Muscle

Abstract: BCAA catabolism in skeletal muscle is regulated by the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, located at the second step in the BCAA catabolic pathway. The activity of the BCKDH complex is regulated by a phosphorylation/dephosphorylation cycle. Almost all of BCKDH complex in skeletal muscle under normal and resting conditions is in an inactive/phosphorylated state, which may contribute to muscle protein synthesis and muscle growth. Exercise activates the muscle BCKDH complex, resulting in enhanced BCAA catabolism. Therefore, exercise may increase the BCAA requirement. It has been reported that BCAA supplementation before exercise attenuates the breakdown of muscle proteins during exercise in humans and that leucine strongly promotes protein synthesis in skeletal muscle in humans and rats, suggesting that a BCAA supplement may attenuate muscle damage induced by exercise and promote recovery from the damage. We have examined the effects of BCAA supplementation on delayed-onset muscle soreness (DOMS) and muscle fatigue induced by squat exercise in humans. The results obtained showed that BCAA supplementation prior to squat exercise decreased DOMS and muscle fatigue occurring for a few days after exercise. These findings suggest that BCAAs may be useful for muscle recovery following exercise.

Lewis Acid-Catalyzed Enantioselective Hydroxylation Reactions of Oxindoles and β-Keto Esters Using DBFOX Ligand

Abstract: The first catalytic enantioselective hydroxylation reaction of both 3-aryl and 3-alkyl-2-oxindoles using the DBFOX−Zn(II) complex, leading to pharmaceutically important chiral 3-hydroxy-2-oxindoles was described. The structure of oxidant was found to play an important role to increase the enantioselectivity. The methodology has successfully applied to the highly enantioselective hydroxylation of β-keto esters using the DBFOX−Ni(II) complex.

Characterization and dielectric behavior of willemite and TiO2-doped willemite ceramics at millimeter-wave frequency

Abstract: Willemite ceramics (Zn2SiO4) have been successfully prepared in the temperature range from 1280 to 1340 ◦ C. It is found that willemite ceramics possess excellent millimeter-wave dielectric properties: a dielectric constant er value of 6.6, a quality factor Q × f value of 219,000 GHz and a temperature coefficient of resonant frequency τf value of −61 ppm/ ◦ C. By adding TiO2 with large positive τf value (450 ppm/ ◦ C), near zero τf value can be achieved in a wide sintering temperature range. With 11 wt% of TiO2 ,a ner value of 9.3, a Q × f value of 113,000 GHz, and a τf value of 1.0 ppm/ ◦ C are obtained at 1250 ◦ C. The relationships between microstructure and properties are also studied. Our results show that willemite with appropriate TiO2 is an ideal temperature stable, low er and high Q × f dielectric for millimeter-wave application.

Comparisons of computed mobile phone induced SAR in the SAM phantom to that in anatomically correct models of the human head

Abstract: The specific absorption rates (SAR) determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct models of the human head when exposed to a mobile phone model are compared as part of a study organized by IEEE Standards Coordinating Committee 34, Sub-Committee 2, and Working Group 2, and carried out by an international task force comprising 14 government, academic, and industrial research institutions. The detailed study protocol defined the computational head and mobile phone models. The participants used different finite-difference time-domain software and independently positioned the mobile phone and head models in accordance with the protocol. The results show that when the pinna SAR is calculated separately from the head SAR, SAM produced a higher SAR in the head than the anatomically correct head models. Also the larger (adult) head produced a statistically significant higher peak SAR for both the 1- and 10-g averages than did the smaller (child) head for all conditions of frequency and position.

Thermal and transport properties of the Heusler-type Fe 2 VAl 1 − x Ge x ( 0 ≤ x ≤ 0.20 ) alloys: Effect of doping on lattice thermal conductivity, electrical resistivity, and Seebeck coefficient

Abstract: We report on the thermoelectric properties of the Heusler-type ${\mathrm{Fe}}_{2}{\mathrm{VAl}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ alloys with compositions $0\ensuremath{\le}x\ensuremath{\le}0.20$. While ${\mathrm{Fe}}_{2}\mathrm{VAl}\phantom{\rule{0.3em}{0ex}}(x=0)$ exhibits a semiconductorlike behavior in electrical resistivity, a slight substitution of Ge for Al causes a significant decrease in the low-temperature resistivity and a large enhancement in the Seebeck coefficient, reaching $\ensuremath{-}130\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{V}∕\mathrm{K}$ for $x=0.05$ at around room temperature. Comparison with the ${\mathrm{Fe}}_{2}{\mathrm{VAl}}_{1\ensuremath{-}x}{\mathrm{Si}}_{x}$ system demonstrates that the compositional variation of the Seebeck coefficient falls on a universal curve irrespective of the doping elements (Ge and Si), both of which are isoelectronic elements. The net effect of doping is most likely to cause a rigid-bandlike shift of the Fermi level from the central region in the pseudogap. In spite of a similar decrease in the electrical resistivity with composition of Ge and Si, the thermal conductivity decreases more rapidly for the Ge substitution. It is concluded that doping of heavier atoms such as Ge reduces more effectively the lattice thermal conductivity while retaining the low electrical resistivity as well as the large Seebeck coefficient.

One-dimensional self-assembly of gold nanoparticles for tunable surface plasmon resonance properties

Abstract: The localized surface plasmon resonance (LSPR) is a collective oscillation of the nanoparticle conduction electrons. LSPR excitation in silver and gold nanoparticles produces strong extinction and scattering spectra that in recent years have been used for important sensing and spectroscopy applications. Tuning the optoelectronic properties by controlling coupled SP modes in metals is one of the major challenges in the area of metal nanomaterials. Here we develop a simple method to fabricate linear-chainlike aggregates of gold nanoparticles (so-called nanochains), tuning the linear optical properties in a wide wavelength range from visible to the near infrared. The aggregation behaviour and linear self-assembly mechanism of citrate-stabilized gold colloids as provoked by the addition of cetyltrimethylammonium bromide (CTAB) are also analysed. The CTAB with appropriate concentration serves as the 'glue' that can link the {100} facets of two neighbour Au NPs, which leads to an anisotropic distribution of the residual surface charge, and this extrinsic electric dipole formation is responsible for the linear organization of the gold NPs into short chains.

Forsterite ceramics for millimeterwave dielectrics

Abstract: The wireless communications have been tremendously developed in the recent ubiquitous age. The utilizable frequency region has been expanded to millimeterwaves because of shortage of conventional frequency regions. For the ultra high frequencies of millimeterwaves, dielectrics with ultra high quality factor Q and low dielectric constant e r are desired. Low e r is necessary to short the delay time of signals and to make devices small in size. Silicates for candidate of millimeterwave materials have low dielectric constant, because of silica-oxygen tetrahedra composed of half covalent bonds. Forsterite (Mg2SiO4) as such kind of silicates has high Q ⋅ f of 270000 GHz and low e r of 6.8. The temperature coefficient of resonant frequency τ f was improved by adding rutile TiO2 with high τ f of plus 450 ppm/∘C. In this paper, these results for forsterite are summarized.

Application of functionally graded material for solid insulator in gaseous insulation system

Abstract: Functionally graded materials (FGM) have spatial distribution of a material property in order to achieve efficient stress control. An application of the FGM to a solid insulator (spacer) for a gaseous insulation system, like gas insulated switchgear, is expected to improve electric field (E-field) distribution around the spacer. In this paper, we describe the applicability of the FGM spacer to gas insulated power equipment. In the FGM spacer, we gave spatial distribution of dielectric permittivity to control the E-field distribution inside and outside the spacer. This paper includes following key results for the applications of the FGM. Firstly, E-field simulation results when applying the FGM by a finite element method are presented, in which we show the effective reduction of the maximum field strength by applying the FGM. Next, a fabrication technique of the FGM spacer sample with not only step-by-step but also continuous changes of permittivity is presented by use of centrifugal force. Finally, dielectric breakdown tests using FGM samples which are accurately controlled the spatial distribution of permittivity are carried out under lightning impulse voltage applications. The test result indicates the increase of breakdown voltage (BDV). From these results, we verified the applicability and the fabrication technique of FGM spacer for improvement of the dielectric strength in the gaseous insulation system.

Microwave dielectric properties and crystal structure of homologous compounds ALa4Ti4O15 (A = Ba, Sr and Ca) for base station applications

Abstract: Homologous compounds ALa4Ti4O15 (A = Ba, Sr and Ca) with high dielectric constant ϵr and quality factor Q × f are candidate materials for dielectric resonators in base station of telecommunication systems. We have investigated the relationship between the microwave dielectric properties and crystal structure of these new materials. Single crystals of CaLa4Ti4O15 were synthesized to analyze the crystal structure precisely. The ceramic discs of the ALa4Ti4O15 (A = Ba, Sr and Ca) were also synthesized and the microwave dielectric properties were measured. Ba-analogy showed the highest ϵr of 44.4 due to the large cationic movement. Ca-analogy showed the highest Q × f of 50,246 GHz due to resemblance in ionic radius between Ca2+ (r = 1.34 A: 12-coordination) and La3+ (r = 1.36 A: 12-coordination) ions. Sr-analogy showed near zero temperature coefficient of resonant frequency τf of −8.4 ppm/°C compared with the others. The relationships between their crystal structures and properties were discussed.

FDTD calculation of whole-body average SAR in adult and child models for frequencies from 30 MHz to 3 GHz.

Abstract: Due to the difficulty of the specific absorption rate (SAR) measurement in an actual human body for electromagnetic radio-frequency (RF) exposure, in various compliance assessment procedures the incident electric field or power density is being used as a reference level, which should never yield a larger whole-body average SAR than the basic safety limit. The relationship between the reference level and the whole-body average SAR, however, was established mainly based on numerical calculations for highly simplified human modelling dozens of years ago. Its validity is being questioned by the latest calculation results. In verifying the validity of the reference level with respect to the basic SAR limit for RF exposure, it is essential to have a high accuracy of human modelling and numerical code. In this study, we made a detailed error analysis in the whole-body average SAR calculation for the finite-difference time-domain (FDTD) method in conjunction with the perfectly matched layer (PML) absorbing boundaries. We derived a basic rule for the PML employment based on a dielectric sphere and the Mie theory solution. We then attempted to clarify to what extent the whole-body average SAR may reach using an anatomically based Japanese adult model and a scaled child model. The results show that the whole-body average SAR under the ICNIRP reference level exceeds the basic safety limit nearly 30% for the child model both in the resonance frequency and 2 GHz band.

Theoretical study on fabrication of functionally graded material with density gradient by a centrifugal solid-particle method

Abstract: Computer simulation was carried out for an estimation of the effect of centrifugal force on the formation of graded distribution of solid spherical particles within molten metal. The difference of migration rate between two kinds of spherical particles with different diameter and density was calculated taking account of the application of a centrifugal solid-particle method. Based on the systematic analysis, the capability of fabrication of the functionally graded materials ring with a unique density gradients which comprise the graded distributions of two kinds of solid particles is discussed. The unique gradient was essentially achieved due to the preferential movement of large particles with low density in comparison to small particles with high density.

Factors affecting the phase and morphology of CaCO3 prepared by a bubbling method

Abstract: Precipitated calcium carbonate (PCC) was prepared by bubbling a CO 2 /N 2 mixed gas into a CaCl 2 solution. The influence of preparation conditions on the phase and morphology of PCC was discussed with the help of XRD and SEM measurements. The results showed that the initial CaCl 2 concentration, flow rate and temperature play an important role on the morphology of PCC. At low initial CaCl 2 concentration or high flow rate, spherical vaterite was preferably formed. Otherwise, the rhombic calcite was ready to form. Temperature is a determining factor on the formation of aragonite. Needle-like aragonite was precipitated at 60 °C. The results also indicated that both the bubbling time and stirring rate have a minor effect on the phase and morphology of PCC.

Environmentally Friendly One-Pot Synthesis of α-Alkylated Nitriles Using Hydrotalcite-Supported Metal Species as Multifunctional Solid Catalysts

Abstract: A ruthenium-grafted hydrotalcite (Ru/HT) and hydrotalcite-supported palladium nanoparticles (Pd(nano)/HT) are easily prepared by treating basic layered double hydroxide, hydrotalcite (HT, Mg(6)Al(2)(OH)(16)CO(3)) with aqueous RuCl(3)n H(2)O and K(2)[PdCl(4)] solutions, respectively, using surface impregnation methods. Analysis by means of X-ray diffraction, and energy-dispersive X-ray, electron paramagnetic resonance, and X-ray absorption fine structure spectroscopies proves that a monomeric Ru(IV) species is grafted onto the surface of the HT. Meanwhile, after reduction of a surface-isolated Pd(II) species, highly dispersed Pd nanoclusters with a mean diameter of about 70 A is observed on the Pd(nano)/HT surface by transmission electron microscopy analysis. These hydrotalcite-supported metal catalysts can effectively promote alpha-alkylation reactions of various nitriles with primary alcohols or carbonyl compounds through tandem reactions consisting of metal-catalyzed oxidation and reduction, and an aldol reaction promoted by the base sites of the HT. In these catalytic alpha-alkylations, homogeneous bases are unnecessary and the only by-product is water. Additionally, these catalyst systems are applicable to one-pot syntheses of glutaronitrile derivatives.

Approximation of aging effect on dielectric tissue properties for SAR assessment of mobile telephones

Abstract: In electromagnetic dosimetry of children heads for mobile telephones, the dielectric properties of biological tissues for adults are so far being used due to the lack of the ones of children. In this paper, we derived an empirical formula according to Lichtenecker's exponential law for the complex permittivity of various tissues as a function of the hydrated rate or the total body water (TBW). We first examined its validity using the data measured by Peyman et al. for rats, and then applied the formula to the dielectric properties of 7-year-old and 3-year-old child head models by means of the relationship between the TBW and the age. With the dielectric properties for children derived in such an approach, we analyzed numerically the spatial peak specific absorption rate (SAR) for a 900-MHz mobile telephone in adult and child head models. As a result, we found that the dielectric properties for children do not affect significantly the 1- or 10- g averaged spatial peak SAR as well as the penetration depth. The finding could be qualitatively explained as cancellation of the increased conductivity and decreased electric field penetrating into the tissue because of the same degree of increase between the conductivity and permittivity in children compared to adults. Even in an extreme case, the age effect on the spatial peak SAR of dielectric properties is still within 10%.

Low resistivity p-ZnO films fabricated by sol-gel spin coating

Abstract: N-doped and In-N-codoped ZnO films were fabricated on quartz glass substrate by sol-gel spin coating. Their p-type conductivities were characterized by the Hall measurements, revealing low resistivities of the order of 10−1Ωcm. Thin-film junctions comprising an undoped ZnO layer and a N-doped ZnO layer displayed the typical rectifying characteristics, suggesting formation of p-n homojunctions at the interfaces.

Chiral recognition in cucurbituril cavities.

Abstract: For the first time, achiral cucurbiturils (CBs) were endowed with significant enantiomeric and distereomeric discrimination by incorporating a strong chiral binder. Calorimetric, nuclear magnetic, light-scattering, and mass spectral studies revealed that (S)-2-methylbutylamine (as a strong binder) can be discriminated by two enantiomeric supramolecular hosts, composed of CB[6] and (R)- or (S)-2-methylpiperazine, with an unprecedented 95% enantioselectivity in aqueous NaCl solution. This is the highest enantioselectivity ever reported for a supramolecular system derived from an achiral host. Similarly, CB[7], with a larger cavity, exhibited diastereoselectivities up to 8 times higher for diastereomeric dipeptides, as demonstrated for L-Phe-L-Leu-NH3+ versus L-Phe-D-Leu-NH3+.

Method and apparatus for detecting charged state of secondary battery based on neural network calculation

Abstract: A neural network type of apparatus is provided to detect an internal state of a secondary battery implemented in a battery system. The apparatus comprises a detecting unit, producing unit and estimating unit. The detecting unit detects electric signals indicating an operating state of the battery. The producing unit produces, using the electric signals, an input parameter required for estimating the internal state of the battery. The input parameter reflects calibration of a present charged state of the battery which is attributable to at least one of a present degraded state of the battery and a difference in types of the battery. The estimating unit estimates an output parameter indicating the charged state of the battery by applying the input parameter to neural network calculation.

Branched-chain amino acid catabolism in exercise and liver disease.

Abstract: Branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, the enzyme catalyst for the second step of the BCAA catabolic pathway, plays a central role in the regulation of BCAA catabolism. The activity of the complex is regulated by a covalent modification cycle in which phosphorylation by BCKDH kinase inactivates and dephosphorylation by BCKDH phosphatase activates the complex. Many studies suggest that control of the activity of the kinase is a primary determinant of the activity of the complex. The kinase exists at all times in the mitochondrial matrix space in two forms, with a large amount being free and a smaller amount bound rather tightly to the BCKDH complex. Only the bound form of the kinase appears to be catalytically active and, therefore, responsible for phosphorylation and inactivation of the complex. alpha-Ketoisocaproate, the transamination product of leucine and the most important known physiological inhibitor of BCKDH kinase, promotes release of the kinase from the complex. alpha-Chloroisocaproate, the analogue of leucine and the most potent known inhibitor of the kinase, is more effective than alpha-ketoisocaproate in promoting release of BCKDH kinase from the complex. Exercise and chronic liver disease (liver cirrhosis) likewise decrease the amount of the kinase bound to the complex in rat liver. The resulting activation of the BCKDH complex appears responsible for the increase in BCAA catabolism caused by exercise and liver cirrhosis. Our findings support the use of BCAA supplements for patients with liver cirrhosis.

Proxy-based sliding mode control for accurate and safe position control

Abstract: High-gain PID position control, which is widely used with industrial robots, involves some risks in cases of abnormal events, such as unexpected environment contacts and temporal power failures. This paper proposes a new position control method to achieve both accurate, responsive tracking during normal operation and smooth, overdamped recovery from a large positional error after abnormal events. The proposed method, which we call proxy-based sliding mode control, is a modified version of sliding mode control adapted to discrete-time systems, and also is an extension of PID control. The validity of the proposed method is demonstrated through experiments

Development of Prediction System for Environmental Burden for Machine Tool Operation

Abstract: Recently, some activities for environmental protection have been attempted to reduce environmental burdens in many fields. The manufacturing field also requires such reduction. Hence, a prediction system for environmental burden for machining operation is proposed based on the Life Cycle Assessment (LCA) policy for the future manufacturing system in this research. This system enables the calculation of environmental burden (equivalent CO2 emission) due to the electric consumption of machine tool components, cutting tool status, coolant quantity, lubricant oil quantity and metal chip quantity, and provides accurate information of environmental burden of the machining process by considering some activities related to machine tool operation. In this paper, the development of the prediction system is described. As a case study, two Numerical Control (NC) programs that manufacture a simple shape are evaluated to show the feasibility of the proposed system.