Critical light scattering in4He near the gas-liquid critical point

Scattered intensities of light were measured near the gas-liquid critical point of ⁴ He at scattering angles of 30, 60, and 90° as functions of the reduced temperature =|T–T _c |/T _c along the critical isochore (T>T _c ) and the coexistence curve (T>T _c ). The temperature range was 3×10 ^–5 <<1.5×10 ^–2 . Critical exponents and coefficients describing divergence of the generalized susceptibility and the correlation length are obtained as (T>T _c )=1.31±0.02, v(T>T _c )=0.66±0.02, ₀ (T>T _c )=4.2±0.6 Å, (T>T _c )=1.32±0.02, v(T>T _c )=0.68±0.02, _± (T>T _c )=2.6±0.7 Å, =0.06±0.06(T>T _c ), 0.05±0.05(T>T _c ), and ₀(T>T _c )/x_± (T>T _c )=3.6±0.4. It is pointed out that the quantal nature of ⁴ He has remarkable influence on the critical behavior of ⁴ He in the above-mentioned temperature region.     

Occurrence of plant sterols in aquatic vertebrates

Plant sterols were found by gas liquid chromatography in the sterols of five species of aquatic vertebrates; mackerel (Scomber japonicus), rainbow trout (Salmo gairdnerii), smelt (Osmerus dentex), sardine (Sardinops melanosticta) and chimera (Chimera phantasma). The sterols of chimera liver, sardine flesh and sardine viscera contained 9.0, 2.4 and 3.1% of C₂₈ and C₂₉ sterols in addition to 86.7, 96.6 and 95.2% of cholesterol. The occurrence of norcholestandienol, campesterol, β-sitosterol and C₂₈ stanol was shown by combined gas chromatography-mass spectrometry. Sperm whale (Physeter catodon) sterols consisted of more than 99% cholesterol with only traces of 22-dehydrocholesterol.     

Muscle stiffness sensor to control an assistance device for the disabled

An innovative sensor has been developed as a man–machine interface to control an assistance device for people with disabilities. This sensor is applied to a mechanical glove that has a grasping function, and its usefulness is demonstrated through experiments. The sensor is attached to the operators skin and detects noninvasively how much the muscle under the sensor has stiffened.This work was presented in part at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003     

Enzyme-linked immunosorbent assay for monitoring toxic dioxin congeners in milk based on a newly generated monoclonal anti-dioxin antibody

To develop an enzyme-linked immunosorbent assay (ELISA) for monitoring the toxicity due to polychlorinated dibenzo-p-dioxins and dibenzofurans contaminated in human breast milk, we have generated novel monoclonal antibodies using some haptenic derivatives linked to bovine serum albumin via the C-1 or C-2 position on the dioxin skeleton. BALB/c or A/J mice were repeatedly immunized with the immunogen, and spleen cells were fused with P3/NS1/1-Ag4-1 myeloma cells. After five fusion experiments, a hybridoma clone was established that secretes an antibody D9-36 group specifically recognizing the major toxic congeners, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), 1,2,3,7,8-pentachlorodibenzo-p-dioxin, and 2,3,4,7,8-pentachlorodibenzofran. An ELISA is developed on the basis of the competitive and labeled-antigen format. The toxic congeners extracted from butter or milk specimens by a novel extraction cartridge and a peroxidase-labeled dioxin analogue were sequentially reacted with a fixed amount of D9-36 in the presence of Triton X-100. The bound fraction was captured on a microtiter plate, immobilizing a second antibody, and the enzyme activity was colorimetrically determined. This ELISA afforded a practical sensitivity (measurable range, 1-100 pg/assay; detection limit, 1.0 pg/assay as 2,3,7,8-TCDD equivalent). The assay values for milk and butter samples were in reasonable accordance with the sum of the toxicity-equivalent quantity of each congener, which had been determined by a high-resolution gas chromatography/high-resolution mass spectrometry method.     

High resolution for single-strand conformation polymorphism analysis by capillary electrophoresis

Since the successful completion of the Human Genome Project, increasing concern is being directed toward the polymorphic aspect of the genome and its clinical relevance. A form of single-strand DNA-conformation polymorphism analysis (SSCP) employing nondenaturing slab-gel electrophoresis (SGE) is applicable to the genetic diagnosis of bladder cancer from urine samples. To bring this technique into routine clinical practice, the use of capillary electrophoresis (CE) is naturally favorable in terms of speed and automation. However, the resolving power of SSCP, a prerequisite basis for reliability required in diagnostics, remains as a challenge for CE systems. We thus focused on this topic and conducted studies on CE instruments equipped with a single capillary or an array of multiple capillaries, using the resolution (Rs) as a quantitative scale for the resolving power. Polymer concentration and buffer are shown to be the decisive parameters. High Rs values of >2.5 are achieved for representative SNPs markers under the optimized conditions, without sacrificing such intrinsic advantages of CE over SGE as the 10-fold quicker migration time and operation that is reproducible, continuous, and automatic. The strategies presented broaden the limits of CE in both the current and related applications.     

Numerical studies on time-domain responses of on-off-keyed modulated optical signals through a dense fog

We present a numerical technique to simulate the propagation characteristics of an on-off-keyed modulated optical signal through fog. The on-off-keyed modulated light (a square wave) is decomposed into a finite number of harmonic components, and a numerical solution for the vector radiative transfer equation is obtained for each harmonic that corresponds to the modulation frequency. With this method we study the distortion and the pulse spread in the received signal due to attenuation and scattering. We investigate the propagation characteristic of the modulated signal with different communication system parameters. This information can be used to study communication channel reliability.     

Interfacial properties of a direct bonded Nd-doped YVO4 and YVO4 single crystal

Laser crystal bonding of a neodymium-doped yttrium orthovanadate (Nd : YVO₄) and a non-doped yttrium orthovanadate (YVO₄) crystal as a cold finger has been demonstrated. Instead of a traditional chemical treatment, a newly developed dry etching process was applied to the preparation for contact of mechanically polished surfaces. In the subsequent heat treatment process, stable heating at 873 K was required to prevent precipitation at the bonded interface. The bonded interface of 3 mm×3 mm was investigated by optical scattering and wavefront distortion measurements. The scattering density around the bonded interface was less than 4.6×10⁶/cm³ and the wavefront distortion caused by the bonded region was assumed to be around 0.04 at 633 nm. Additional magnified inspection showed that atoms in the bonded region were well arranged with the same regularity as the bulk crystal. The diffusion coefficient of Nd³⁺ ions in the YVO₄ crystal was estimated at 2.3×10^–23 m²/s at 873 K.     

The mechanism of sperm-oocyte fusion in mammals

Sperm-oocyte fusion is one of the most impressive events in sexual reproduction, and the elucidation of its molecular mechanism has fascinated researchers for a long time. Because of the limitation of materials and difficulties in analyzing membrane protein-protein interactions, many attempts have failed to reach this goal. Recent studies involving gene targeting have clearly demonstrated the various molecules that are involved in sperm-oocyte binding and fusion. Sperm ADAMs (family of proteins with a disintegrin and metalloprotease domain), including fertilin alpha, fertilin beta and cyritestin, have been investigated and found to be important for binding rather than for fusion and painstaking studies have raised suspicions that their putative receptors, oocyte integrins, are necessary for the sperm-oocyte interaction. Recently, several studies have focused the spotlight on CD9 and glycosylphosphatidylinositol (GPI)-anchored proteins on oocytes, and epididymal protein DE on sperm, as candidate molecules involved in sperm-oocyte fusion. Lack of, or interference with the function of, these proteins can disrupt the sperm-oocyte fusion without changing the binding. In this review we highlight the candidate molecules involved in the sperm-oocyte interaction suggested from the recent progress in this research field.     

Microstructural analysis of the deformation range under nano-indentation in beta-SiC

As a powerful tool to analyse microstructural evolution under irradiation and the interaction of moving dislocations with radiation-induced defects, a focused ion beam (FIB) method was applied to ion-irradiated SiC followed by the nano-indentation test. An FIB method has excellent capability to prepare thin foils from the area of interest with a high accuracy of location and wide flexibility in the sampling direction. These advantages are demonstrated in the application to Si ion-irradiated SiC by transmission electron microscope observation.