Showing papers by "Utsunomiya University published in 2002"

Experimental Observation of Radiation from Cherenkov Wakes in a Magnetized Plasma

Abstract: A proof-of-principle experiment demonstrates the generation of radiation from the Cherenkov wake excited by an ultrashort- and ultrahigh-power pulse laser in a perpendicularly magnetized plasma. The frequency of the radiation is in the millimeter range (up to 200 GHz). The intensity of the radiation is proportional to the magnetic field intensity as expected by theory. Polarization of the emitted radiation is also detected. The difference in the frequency of the emitted radiation between these experiments and previous theory can be explained by the electrons' oscillation in the electric field of a narrow column of ions in the focal region.

Analysis of chatter suppression in vibration cutting

Abstract: The occurrence of chatter is strongly influenced by the tool geometry in conventional cutting. Therefore, the tool geometry is regarded as a very important factor. On the other hand, it is known that vibration cutting is capable of cutting hardened steels. However, the theoretical explanation for finish hard-cutting with vibration cutting is still unknown. In this paper, experimental investigations show that chatter is effectively suppressed without relying on the tool geometry, and the work displacement amplitudes are reduced from a wide range of 10–102 μm to the range of 3–5 μm by applying vibration cutting. In order to study the precision machining mechanism of vibration cutting, a new cutting model which contains a vibration cutting process is proposed. Simulations of the chatter model exhibit the main feature of chatter suppression in vibration cutting. The simulation results are in good agreement with the measurement values and accurately predict the work displacement amplitudes of vibration cutting.

Hygiene measures considering actual distributions of microorganisms in Japanese households

Abstract: Aims: Effective household hygiene measures require that sources of bacterial contamination and the places to which contamination spreads be carefully identified. Therefore, a study was performed to examine the distribution of microorganisms throughout ordinary households in Japan, which has its own unique customs of daily life and food preparation. Methods and Results: Using the stamping method, samples were taken from 100 different places and items in each of 86 households. This study found kitchens/dining rooms to have the greatest level of microbial contamination and bathrooms, the next highest level. Toilets (water closets) were found to have an unexpectedly low level of bacterial contamination. The largest bacterial counts were found on items such as drain traps, dish-washing sponges, counter towels, sinks, dish-washing tubs, and bathroom sponges. Conclusions: It is necessary to carefully identify both the items that can become instruments for spreading bacterial contamination and the places that easily become subject to secondary contamination, and then to take timely and effective disinfection/sanitizing measures. Significance and Impact of the Study: The data gathered in this study will be very valuable for anticipating the pathways over which bacteria are transported and prioritizing disinfection targets, to make effective disinfection possible.

Seismoelectromagnetic Effect Associated with the İzmit Earthquake and Its Aftershocks

Abstract: In order to investigate the resistivity structure beneath the northern and the southern branches of the western part of the North Anatolian Fault Zone (NAFZ), which has been known as a seismic gap area, we started wideband magnetotelluric (MT) measurements on 27 July 1999, along a north-south profile crossing the northern branch near Izmit and the southern branch near Iznik. When the Izmit (Kocaeli) earthquake ( M w 7.4) occurred on 17 August 1999, MT fields were being measured at five sites, four of which happened to be located near the surface rupture zone associated with the mainshock, and large variations in the MT fields were observed in association with seismic waves. We propose motional electromagnetic induction in the electrically conducting crust, which vibrates under the Earth's magnetic field, as one of the possible generation mechanisms for such MT field variations. For more detailed studies of such a mechanism, we installed a wideband MT instrument and a three-component seismometer at two of the four sites on 16 September 1999 and made simultaneous measurements during several aftershocks. The estimate of the order of the magnitude of motional electromagnetic response, derived from the MT fields and ground motion observed during a large aftershock ( M 4.5), supports our claim that the seismo-dynamo effect is a plausible mechanism for variations in the MT fields associated with the seismic waves. Manuscript received 31 July 2000.

Rapid suppression of protein degradation in skeletal muscle after oral feeding of leucine in rats.

Abstract: A diet containing adequate amounts of protein rapidly suppresses myofibrillar protein degradation in rats and mice. This study determined whether dietary amino acids inhibit postprandial protein degradation in rat skeletal muscle. When rats fed on a 20% casein diet for 1 h after 18 h starvation, the rate of myofibrillar protein degradation measured by N τ -methylhistidine release from the isolated extensor digitorum longus muscle was significantly ( p p p p

Which side of the π-macrocycle plane of (bacterio)chlorophylls is favored for binding of the fifth ligand?

Abstract: Reported crystallographic data and calculated molecular models indicated that chlorophyll (Chl) a and bacteriochlorophyll (BChl) a tend to bind the fifth ligand on the side of the macrocycle where the C132-(R)-methoxycarbonyl moiety protrudes (denoting the ‘back’ side). The crystal structures of 34 photosynthetic proteins possessing (B)Chl cofactors revealed that most of Chl a and BChl a (and b) are coordinated by any peptidyl residue (e.g., histydyl-imidazolyl group), peptidyl backbone or water from the ‘back’ side. Almost all the cofactors that bind a water molecule as the fifth ligand in these proteins have a ‘back’ configuration. Theoretical model calculations for methyl chlorophyllide a (MeChlid a) and methyl bacteriochlorophyllide a (MeBChlid a) bound to an imidazole molecule indicated that the ‘back’ side is energetically favored for the ligand binding. These results are consistent with the fact that ethyl chlorophyllide a (EtChlid a) dihydrate crystal consists of the ‘back’ complex. The modeling also showed that both removal and stereochemical inverse of the C132-methoxycarbonyl group affect the relative stability between the ‘back’ and ‘face’ complexes. The effect of the C132-moiety on the choice of the macrocycle side for the ligand binding is discussed in relation to the function of P700.

Bacterial contamination of Japanese households and related concern about sanitation.

Abstract: The bacterial contamination of Japanese homes and the attitudes of Japanese people toward sanitation were studied. By taking bacterial counts of approximately 90 places each in five homes, this study found kitchens to have the greatest degree of bacterial contamination, followed by bathing rooms. Toilets had less bacterial contamination than was expected. While concern about bacteria on highly contaminated items such as sponges, towels for wiping counters, and other reservoirs/disseminators was common, there was a relative lack of concern regarding contact surfaces such as dining tables. It is believed that an in-depth study of bacterial contamination in the home and concern about it would lead to the promotion of greater public understanding of home sanitation and help to facilitate the provision of useful information and products to the public.

Micro-Phase Separation in Binary Mixed Langmuir Monolayers of n-Alkyl Fatty Acids and a Perfluoropolyether Derivative

Abstract: Micro-phase separation in binary mixed Langmuir monolayers of cadmium salts of n-alkyl fatty acids (CH3(CH2)n-2COOH; Cn (n = 18, 20, 22, 24)) and a perfluoropolyether surfactant (F(CF(CF3)CH2O)3CF(CF3)COOH, PFPE) is studied by film balance measurement and atomic force microscopy (AFM). At different temperatures, mixtures of Cn/PFPE in chloroform were spread onto the aqueous Cd2+ subphase and deposited on silicon wafers. AFM images showed that Cn and PFPE separate into microscopic domains of condensed phase and a surrounding matrix of expanded phase, respectively, in their mixed monolayers. The morphological feature of phase-separated structures was characterized by characteristic length (λ) expressing the periodicity of two-phase distribution and fractal dimension (D) of Cn domains reflecting the complexity of domain shape, which were determined through AFM image analyses. It was found that the monolayer morphologies systematically vary with alkyl chain length of Cn and temperature of the water surface; c...

Analysis of Oil Film Thickness and Heat Transfer on a Piston Ring of a Diesel Engine: Effect of Lubricant Viscosity

Abstract: The effect of lubricant viscosity on the temperature and thickness in oil film on a piston ring in a diesel engine was analyzed by using unsteady state thermohydrodynamic lubrication analysis, that is Reynolds equation and an unsteady state two-dimensional (2-D) energy equation with heat generated from viscous dissipation. The oil film viscosity was then estimated by using the mean oil film temperature and the shear rate for multi grade oils. The shear rate between the ring and liner becomes higher, so that the viscosity for the multi grade oil is affected by the oil film temperature and shear rate, and the viscosity becomes lower. Under low temperature condition, the viscosity becomes lower due to viscous heating and shear rate and under higher temperature condition, the viscosity affected by the shear rate becomes lower. The oil film thickness between the ring and liner decreases with decrease of the oil viscosity, and it is the thinnest that the oil film thickness is calculated by using the viscosity estimated by both the shear rate and the oil film temperature. Moreover, the heat transfer at ring and liner surfaces was examined.Copyright © 2002 by ASME

Biodegradation of β-1,4-linked polyglucuronic acid (cellouronic acid)

Abstract: Biodegradability of β-1,4-linked polyglucuronic acid (cellouronicacid), which was prepared from regenerated cellulose by2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation underaqueous conditions, was examined by enzymatic treatments and incubationtreatments with microorganisms collected from some soil samples. Degradation ofcellouronic acid was traced by size exclusion chromatography (HPSEC) or totalorganic carbon (TOC) of the treated products or solutions, respectively.Cellouronic acid was depolymerized by a commercial crude cellulase anddecreasedin its weight average degree of polymerization from about 1600 to 40 by thecellulase treatment at 20 °C for 40 days. 13C-NMRanalysis and liquid chromatography of the treated products showed thathydrolysis-type enzymes present in the crude cellulase as contaminantsprimarilydepolymerized cellouronic acid to give glucuronic acid. When aqueous solutionscontaining cellouronic acid were incubated with soil microorganisms for morethan 3 days, the TOC values decreased to less than 20% of the initial value,depending on molecular weight of the cellouronic acid used. The decreasing rateof TOC for cellouronic acid was clearly higher than that ofcarboxymethylcellulose, which is one of the cellulose derivatives havingcarboxymethyl substituents. These results imply that cellouronic acid has bothbiodegradability and metabolizability in the natural environment.

Small electric and magnetic signals observed before the arrival of seismic wave

Abstract: Electric and magnetic data were obtained above the focal area in association with the 1999 Izmit, Turkey earthquake. The acquired data are extremely important for studies of electromagnetic phenomena associated with earthquakes, which have attracted much attention even without clear physical understanding of their characteristics. We have already reported that large electric and magnetic variations observed during the earthquake were simply due to seismic waves through the mechanism of seismic dynamo effect, because they appeared neither before nor simultaneously with the origin time of the earthquake but a few seconds later, with the arrival of seismic wave. In this letter we show the result of our further analyses. Our detailed examination of the electric and magnetic data disclosed small signals appearing less than one second before the large signals associated with the seismic waves. It is not yet solved whether this observational fact is simply one aspect of the seismic dynamo effect or requires a new mechanism.

Runaway current termination in JT-60U

Abstract: Termination of the runaway electron current generated during plasma disruptions is found in JT-60U during simulated vertical plasma displacement events where the safety factor at the plasma surface qs decreases. For all discharges with runaway electron generation, the runaway current disappears for qs≥2 with the appearance of spikes in the magnetic fluctuations. The growth rate of the spikes in the magnetic fluctuations decreases by an order of magnitude during the termination of runaway current. Corresponding to the loss of runaway electrons by magnetic fluctuations, heat flux pulses are measured at the inner divertor plates, which indicates interaction of the wall with the runaway electrons. The halo current during runaway termination is small and increases after runaway termination with a dominant toroidal mode of n = 1.

Discrimination between mono- and trimethylated cap structures by two isoforms of Caenorhabditis elegans eIF4E.

Abstract: Primitive eukaryotes like Caenorhabditis elegans produce mRNAs capped with either m7GTP or m32,2,7GTP. Caenorhabditis elegans also expresses five isoforms of the cap-binding protein eIF4E. Some isoforms (e.g. IFE-3) bind to m7GTP–Sepharose exclusively, whereas others (e.g. IFE-5) bind to both m7GTP– and m32,2,7GTP–Sepharose. To examine specificity differences, we devised molecular models of the tertiary structures of IFE-3 and IFE-5, based on the known structure of mouse eIF4E-1. We then substituted amino acid sequences of IFE-5 with homologous sequences from IFE-3. As few as two changes (N64Y/V65L) converted the cap specificity of IFE-5 to essentially that of IFE-3. Molecular dynamics simulations suggested that the width and depth of the cap-binding cavity were larger in IFE-5 than in IFE-3 or the N64Y/V65L variant, supporting a model in which IFE-3 discriminates against m32,2,7GTP by steric hindrance. Furthermore, the affinity of IFE-5 (but not IFE-3) for m32,2,7GTP was reversibly increased when thiol reagents were removed. This was correlated with the formation of a disulfide bond between Cys-122 and Cys-126. Thus, translation of m32,2,7GTP-capped mRNAs may be regulated by intracellular redox state.

Propagation of short intense laser pulses in gas-filled capillaries.

Abstract: The guided laser pulse propagation and wake-field generation are studied in a wide (in comparison with the laser spot size) gas-filled capillary with an on-axis gas density depletion, which can be produced by a rapid spin of the capillary around its axis or by radially propagating shock waves generated in a piezoceramic tube. A single equation for the wake-field potential, which describes the fully relativistic plasma response in the presence of optical field ionization (OFI) of a gas, is derived and used to demonstrate a guided propagation of a short intense laser pulse over many Rayleigh lengths in a leaky plasma channel produced by the pulse due to OFI in the capillary filled with a radially inhomogeneous gas. The efficient generation of a regular wake field over long distances suitable for the laser wake-field accelerators is shown.

Observation of multi TeV diffuse gamma-rays from the galactic plane with the tibet air shower array

Abstract: Data from the Tibet III air shower array (with energies around 3 TeV) and from the Tibet II array (with energies around 10 TeV) have been searched for diffuse gamma rays from the Galactic plane. These arrays have an angular resolution of about 09. The sky regions searched are the inner Galaxy, 20? ? l ? 55?, and outer Galaxy, 140? ? l ? 225?, and |b| ? 2? or ? 5?. No significant Galactic-plane gamma-ray excess was observed. The 99% confidence level upper limits for gamma-ray intensity obtained are (for |b| ? 2?) 1.1 ? 10-15 cm-2 s-1 sr-1 MeV-1 at 3 TeV and 4.1 ? 10-17 cm-2 s-1 sr-1 MeV-1 at 10 TeV for the inner Galaxy, and 3.6 ? 10-16 cm-2 s-1 sr-1 MeV-1 at 3 TeV and 1.3 ? 10-17 cm-2 s-1 sr-1 MeV-1 at 10 TeV for the outer Galaxy, assuming a differential spectral index of 2.4. The upper limits are significant in the multi-TeV region when compared to those from Cerenkov telescopes in the lower energy region and other air shower arrays in the higher energy region; however, the results are not sufficient to rule out the inverse Compton model with a source electron spectral index of 2.0.

Assembly of puzzles using a genetic algorithm

Abstract: In this paper, we proposed a method for solving the rectangle piece jigsaw puzzle assembly problem. A shape of a piece is a rectangle, and a picture of a puzzle is only painted in black and white, i.e., puzzles are processed as binary images. The assembly of the puzzle is performed only using information of the pixel value on the border line of the pieces. This problem cannot be solved by the simple local piece matching because there are many similar pieces. Global matching is required. The proposed method utilizes a genetic algorithm (GA) to search the optimum piece arrangement because GA has the ability to find the global solution in the large optimization space. The proposed method correctly assembled all pieces in the 8 /spl times/ 8-piece puzzle.

Cascaded GI-fiber chips with a wedge-shaped end for the coupling between an SMF and a high-power LD with large astigmatism

Abstract: A novel lensed fiber for high-efficiency coupling between a single-mode fiber (SMF) and a high-power laser diode (LD) with large astigmatism of 176 /spl mu/m is proposed and demonstrated. We experimentally confirmed that the proposed lensed fiber had a minimum coupling loss of 2.5 dB including a reflection loss of 0.3 dB at both ends of the fiber. In addition the new configuration had a long working distance of 67 /spl mu/m. We also investigated the tolerance characteristics for various displacements.

The non-linear phenomena in vibration cutting system The establishment of dynamic model

Abstract: It is well-known that vibration cutting is an effective method to cut materials with accuracy. However, it often suffers from unevenness of surface roughness caused by the non-linear vibration phenomena in tool–work vibration system. To solve this problem, we propose a vibration cutting model described by two-dimensional differential equations to analyze the non-linear phenomena. This non-linear model reproduces the basic features of the real vibration cutting systems, that is, the reduction of the cutting force and the displacement of work by pulsing of the cutting force. In this report, our experiment shows that various non-linear phenomena exist in the vibration cutting system. Our non-linear model for the vibration cutting produce behaviors which qualitatively agree with these various non-linear phenomena. These behaviors can be classified by the Lyapunov exponents.

Labdane-type Diterpene Dialdehyde, Pungent Principle of Myoga, Zingiber mioga Roscoe

Abstract: The pungent principle of myoga (Zingiber mioga Roscoe) was identified as (E)-8β(17)-epoxylabd-12-ene-15,16-dial (miogadial) on the basis of its physical and spectroscopic properties (MS, NMR, IR, and UV). Galanal A and B, isolated as well as miogadial, had no hot taste. Reduced miogadial also was tasteless. The pungency of miogadial depended on the presence of αβ-unsaturated-1,4-dialdehyde group.

Experimental observation of short-pulse upshifted frequency microwaves from a laser-created overdense plasma.

Abstract: A short and frequency upshifted from a source microwave pulse is experimentally generated by the overdense plasma that is rapidly created by a laser. The source wave, whose frequency is 9 GHz, is propagating in the waveguide filled with tetrakis-dimethyl-amino-ethylene gas, which is to be converted to the overdense plasma by the laser. The detected frequency of the pulse is over 31.4 GHz and its duration is 10 ns. This technique has the potential for the generation of a tunable frequency source.

Determination of sulfur dioxide based on a silver dispersed functional self-assembled electrochemical sensor

Abstract: A new and simple amperometric sensor for sulfur dioxide (SO 2 ) has been constructed based on the self-assembly of (3-mercaptopropyl)trimethoxysilane (MPS) over a glassy carbon (GC) electrode followed by the complexation with silver. The silver dispersed onto the self-assembled surface exhibited excellent electrocatalytic activity for the determination of sulfur dioxide at a reduced potential (+0.3 V) with good sensitivity in a wide concentration range from 0.6 to 88 ppm with a correlation coefficient of 0.9989. The proposed sensor is easy to fabricate and has the advantages of good stability, reproducibility and rapid response.