Utsunomiya University

About: Utsunomiya University is a education organization based out in Utsunomiya, Japan. It is known for research contribution in the topics: Laser & Holography. The organization has 4139 authors who have published 6812 publications receiving 91975 citations. The organization is also known as: Utsunomiya daigaku.

Lack of promoting effects of the electromagnetic near-field used for cellular phones (929.2 MHz) on rat liver carcinogenesis in a medium-term liver bioassay.

Abstract: The possible cancer promotion potential of local exposure to a pulse modulated 929.2 MHz electromagnetic near-field on chemically-initiated rat liver carcinogenesis was investigated employing a medium-term bioassay. A 929.2-MHz electromagnetic near-field of time division multiple access (TDMA) signal for PDC (Personal Digital Cellular, Japanese cellular telephone standard) system was directed to rats through a quarter-wavelength monopole antenna. Maximum local specific absorption rates (SARs) on temporal average were 7.2-6.6 W/kg within the whole body and 2.0-1.7 W/kg within the liver, which was the target organ. The whole-body average SARs on temporal average were 0.80-0.58 W/kg. Temporal peak SARs had three times these values due to the duty ratio of the PDC signal. Exposure was for 90 min a day, 5 days a week, over 6 weeks. The exposure apparatus was specially designed for this experiment, to allow exposure of the lateral mid-section of the rat body to the electromagnetic near-field. Male F344 rats, 6 week-old, were initially (at week 0) given a single dose of diethylnitrosamine (DEN, 200 mg/kg body wt, i.p.). At 2 weeks later, exposure (48 rats) or sham-exposure (48 rats) was started. The exposure of electromagnetic near-fields was performed using the exposure apparatus mentioned above. At week 3, all rats were subjected to a 2/3 partial hepatectomy. At week 8 (i.e. after 6 weeks exposure or sham-exposure), the experiment was terminated and all rats were killed. Carcinogenic potential was scored by comparing the numbers and areas of the induced glutathione S-transferase placental form (GST-P) positive foci in the livers of the exposed and sham-exposed rats. A further group of 24 animals, given only DEN and partial hepatectomy, served as the controls. The numbers (no./cm2) of GST-P positive foci were 4.61 +/- 1.77, 5.21 +/- 1.92 (P < 0.05, versus control) and 4.09 +/- 1.47 and the areas (mm2/cm2) were 0.30 +/- 0.16, 0.36 +/- 0.21 and 0.28 +/- 0.15, for the exposed, sham-exposed and control groups, respectively. There were no significant differences between the exposed and sham-exposed groups. These findings clearly indicated that local body exposure to a 929.2-MHz field, modulated in a PDC waveform, has no significant effect on rat liver carcinogenesis under the experimental conditions employed.

Structural diversity of strigolactones and their distribution in the plant kingdom

Abstract: Strigolactones (SLs) are plant secondary metabolites that were first identified as germination stimulants for the root parasitic weeds witchweeds (Striga spp.) and broomrapes (Orobanche and Phelipanche spp.). In the rhizosphere, SLs also promote root colonization by arbuscular mycorrhizal fungi. In plants, SLs as a novel class of plant hormones regulate various aspects of plant growth and development. Herein I discuss structural diversity of naturally occurring SLs and their distribution in the plant kingdom.

Blue-to-red chromatic sensor composed of gold nanoparticles conjugated with thermoresponsive copolymer for Thiol sensing.

Abstract: We describe the first determination of thiol compounds with gold nanocomposites composed of gold nanoparticles and thermoresponsive copolymers having polyamino groups. The gold nanocomposites, which are used as a chromatic sensor, reveal chromatic change from blue to red with thermal stimuli, heating followed by cooling the solution. The blue-to-red chromatic change results from disassembly of the gold nanocomposites, which arises from shrinkage of the thermoresponsive copolymers bound to the gold nanoparticle surfaces due to the phase transition induced by thermal stimuli. The disassembly is inhibited by addition of thiol compounds through displacement of the adhered thermoresponsive copolymers. The detached copolymers no longer influence morphological change of the gold nanocomposites. Corresponding with increase of concentration of the thiol compounds, a solution of the gold nanocomposites after the thermal stimuli shows chromatic change, which was quantified with the a* value in L*a*b* chromatic coordinates. A linear relationship between the a* value and concentration of cysteine, examined as a bio-important thiol, is obtained below 7x10(-6) mol dm(-3), estimating a detection limit defined as 3sigma of the blank to be 2.8x10(-7) mol dm(-3). The chromatic sensor of the gold nanocomposites is applied to the determination of cysteine in commercial supplements containing ascorbic acid, which seriously interferes with redox-based determination of cysteine. Analytical results obtained with the chromatic sensor are identical to those obtained with HPLC.

Dual-comb spectroscopic ellipsometry.

Abstract: Spectroscopic ellipsometry is a means of investigating optical and dielectric material responses. Conventional spectroscopic ellipsometry is subject to trade-offs between spectral accuracy, resolution, and measurement time. Polarization modulation has afforded poor performance because of its sensitivity to mechanical vibrational noise, thermal instability, and polarization-wavelength dependency. We combine spectroscopic ellipsometry with dual-comb spectroscopy, namely, dual-comb spectroscopic ellipsometry. Dual-comb spectroscopic ellipsometry (DCSE). DCSE directly and simultaneously obtains the ellipsometric parameters of the amplitude ratio and phase difference between s-polarized and p-polarized light signals with ultra-high spectral resolution and no polarization modulation, beyond the conventional limit. Ellipsometric evaluation without polarization modulation also enhances the stability and robustness of the system. In this study, we construct a polarization-modulation-free DCSE system with a spectral resolution of up to 1.2 × 10−5 nm throughout the spectral range of 1514–1595 nm and achieved an accuracy of 38.4 nm and a precision of 3.3 nm in the measurement of thin-film samples.

Submanifolds with harmonic mean curvature vector field in contact 3-manifolds

Abstract: Biharmonic or polyharmonic curves and surfaces in 3-dimensional contact manifolds are investigated. Introduction. This paper concerns curves and surfaces in 3-dimen- sional contact manifolds whose mean curvature vector eld is in the kernel of certain elliptic dieren tial operators. First we study submanifolds whose mean curvature vector eld is in the kernel of the Laplacian (submanifolds with harmonic mean curvature vector elds). The study of such submanifolds is inspired by a conjecture of Bang-yen Chen (14):