Inter-laboratory evaluation studies for development of notified ELISA methods for allergic substances (wheat)

Extracts of sausage, sauce, pasta sauce, fish paste and cereal spiked with wheat standard protein at a level of 5-20 ng/mL as sample solutions were analyzed in replicate in 10 laboratories. Coefficients of variation (CVs) of both ELISA methods using a Wheat Protein ELISA Kit (Gliadin kit) and a FASTKIT Wheat ELISA Kit (Wheat ELISA kit) were mostly below 10%. Mean recoveries of the wheat standard protein from the food extracts were over 40% in the two ELISA methods except those from cereal extract determined using the Wheat ELISA kit. Repeatability relative standard deviations of wheat standard protein in the five food extracts were in the ranges of 16-26.9% and 3.7-36.2% for the Gliadin kit and the Wheat ELISA kit, respectively. Reproducibility relative standard deviations of wheat standard protein in the five food extracts were 21.6-38.5%, 29.7-53.8% for the Gliadin kit and the Wheat ELISA kit, respectively. The recoveries of wheat standard protein from the cereal extract were improved by the increasing the amount of antibody coated on the plate in the Wheat ELISA kit. The detection limits of both ELISA methods were 1 ng/mL in sample solutions. These results suggested that the notified ELISA methods are reliable and reproducible for the inspection of wheat protein levels in extracts of sausage, sauce, pasta sauce, fish paste and cereal.     

Inter-laboratory evaluation studies for development of notified ELISA methods for allergic substances (milk)

Extracts of sausage, sauce, cookie, cereal and pasta sauce spiked with milk standard protein at a level of 5-20 ng/mL as sample solutions were analyzed in replicate in 10 laboratories. Coefficients of variation (CVs) of the three ELISA methods using a Milk Protein Casein ELISA Kit (Casein kit), a Milk Protein Beta-Lactoglobulin ELISA Kit (Beta-Lactoglobulin kit) and a FASTKIT Milk ELISA Kit (Milk ELISA kit) were mostly below 10%. Mean recoveries of the milk standard protein from the food extracts were over 40% in the three ELISA methods with a few excertions. The recoveries of milk standard protein from the sauce extract in Casein kit were improved by adjusting the extract to neutrality before the Casein kit assay. The recoveries of milk standard protein from cookie, cereal and pasta sauce were improved by the increasing the amount of antibody coated in the Milk ELISA kit. The detection limits of all the ELISA methods were 1 ng/mL in sample solutions. These results suggested that the notified ELISA methods are reliable and reproducible for the inspection of milk protein levels in extracts of sausage, sauce, cookie, cereal and pasta sauce.     

Control of Thermally Induced Vibration in a Composite Beam with Damping Effect

ABSTRACT

This article deals with control of thermally induced vibration in a composite beam with damping effect. The beam consists of a central thermoelastic structural layer and two outer piezothermoelastic layers. The thermoelastic vibration in the beam is suppressed by the superposition of electroelastic vibration. The electroelastic vibration is repeatedly excited through application of electric potential differences across the piezoelectric layers. The initiation and termination times of the applied electric pulses are determined by a method similar to the optimization procedure developed previously by the authors. The amplitudes of the applied electric pulses are determined using a control method based on speed feedback. Numerical results for an aluminum/PZT ceramic beam are illustrated graphically.     

Inverse Problem of a Piezothermoelastic Cylinder Subject to Transient Heating

An inverse problem of a radially polarized piezoelectric hollow circular cylinder of crystal class 6 mm is investigated. It is assumed that a voltage induced by the action of a time-varying temperature applied to the inner surface of the cylinder is measured on the outer surface. The inverse problem entails a determination of the heating temperature from knowledge of the measured voltage. First, an exact solution to the problem is found by solving the equations of equilibrium and electrostatics for the cylinder subject to the prescribed boundary conditions. Then a least-squares residual method that incorporates Lagrange multipliers for satisfaction of the boundary equations is employed to derive an approximate analytic solution. Both formulations are utilized in order to calculate the unknown heating temperature, and the corresponding temperature, displacement and stress fields in a cylinder of cadmium selenide. Numerical results based upon the least-squares residual formulation are found to compare favorably with those obtained by the exact analysis.     

Electrochemical corrosion of platinum electrode in concentrated sulfuric acid

We report on the electrochemical corrosion of a Pt electrode in strong sulfuric acid. The electrochemical measurements were conducted using a Pt-flag working electrode, Ag/Ag₂SO₄ reference electrode and Pt counter electrode at 25 °C. The measured cyclic voltammograms significantly changed in the H₂SO₄ concentration range of 0.5–18 mol dm⁻³, especially from 14 to 18 mol dm⁻³. After successive potential sweeps for 15 h in 16 mol dm⁻³ H₂SO₄, a weight loss of the Pt-flag electrode was realized. In contrast, a controlled potential electrolysis by cathodic polarization caused a weight gain, which was attributed to sulfur deposition by the H₂SO₄ reduction. The subsequent anodic polarization produced corrosion of the deposited sulfur. Consequently, the alternating polarization generated platinum corrosion, resulted in the production of platinum and sulfur composite particulates in the solution.     

Physical properties of a new cuprate superconductor Pr2Ba4Cu7O15–δ

We present studies of the thermal, magnetic, and electrical transport properties of reduced polycrystalline Pr₂Ba₄Cu₇O_15?δ (Pr247) showing a superconducting transition at T_c=10–16 K, and compare them with those of as-sintered non-superconducting Pr247. The electrical resistivity in the normal state exhibited T² dependence up to approximately 150 K. A clear specific heat anomaly was observed at T_c for Pr247 reduced in a vacuum for 24 h, proving the bulk nature of the superconducting state. By the reduction treatment, the magnetic ordering temperature T_n of Pr moments decreased from 16 to 11 K, and the entropy associated with the ordering increased, while the effective paramagnetic moments obtained from the DC magnetic susceptibility varied from 2.72 to 3.13μ_B. The sign of Hall coefficient changed from positive to negative with decreasing temperature in the normal state of a superconducting Pr247, while that of the as-sintered one was positive down to 5 K. The electrical resistivity under high magnetic fields was found to exhibit T^α dependence (α=0.08–0.4) at low temperatures. A possibility of superconductivity in the so-called CuO double chains is discussed.

PACS: 74.72.Jt; 74.25.Bt; 75.40.Cx; 74.25.Fy     

Long-Term Stability of 0.65-μm Radiation Thermometers at NMIJ

Narrow-band radiation thermometers with center wavelengths near 0.65 μm are frequently used as standard thermometers at high temperatures. The long-term stability of ten Topcon 0.65-μm radiation thermometers was assessed at NMIJ by using fixed-point blackbodies and spectral responsivity measurements. Most of the changes are due to shifts in the center wavelength of the interference filters to longer wavelengths. Even when the center wavelengths shifted, the filter widths and transmittances remained quite stable for some radiation thermometers, but one was found for which the bandwidth increased from 15.7 to 17.2 nm and the transmittance decreased by 6%. Three Barr filters were found to be very stable in wavelength. The output signals of 0.65-μm Topcon radiation thermometers were within 2% · year⁻¹ without correcting for the wavelength change and within 0.2% · year⁻¹ after the correction. Keeping the objective lens clean is very important for radiation thermometers. Large output decreases were observed in early 2000 for many radiation thermometers at NMIJ. The output changes were as large as 1% and were recovered by cleaning the objective lens.     

Tensile Ductility of Superplastic Al2O3–Y2O3–Si3N4/SiC Composites

Si₃N₄/SiC composites are ceramic materials that exhibit excellent performance for high-temperature applications. Prepared from an ultrafine amorphous Si-C-N powder, sintered materials are constituted mainly of a β -Si₃N₄ matrix with SiC inclusions and have a very small grain size (less than 1 μm). Such a microstructure is propitious for superplastic forming. Superplasticity has been studied in tension, from 1550° to 1650°C, under nitrogen atmosphere. Elongations over 100% have been achieved. In many cases, at the highest temperatures and slowest strain rates, materials are damaged by different processes, including microcracking, cavitation, and chemical decomposition. A map of the most suitable (strain-rate/temperature) domain has been established. It allows the prevention of any structural alteration by selecting carefully the testing conditions. Since specimens suffered considerable strain-induced hardening, sources for this phenomenon are examined. Although the experiments have involved high temperature and extensive strain, neither static nor dynamic grain growth has occurred. Crystallization of the amorphous grain-boundary phase, which is reported in most cases, may be invoked. However, based on microstructural observations, it is not the unique origin for flow hardening.     

Fabrication of Nanograined Silicon Carbide by Ultrahigh-Pressure Hot Isostatic Pressing

Dense nanograined SiC ceramics were obtained by using hot isostatic pressing (HIP). The starting powder was ultrafine β-SiC powder, which had a mean particle size of 30 nm and contained 3.5 wt% free carbon. SiC powders-both boron-doped and undoped-were densified via HIP under an ultrahigh pressure of 980 MPa at a temperature of 1600°C. Both doped and undoped SiC attained the same density (3.12 g/cm³) (relative density of 97.1%). The average grain sizes of boron-doped and undoped SiC were 200 and 30 nm, respectively. The compressive flow stress of undoped SiC was 3 times higher than that of boron-doped SiC at temperatures of 1800° and 1700°C; however, the flow stresses of both materials were almost the same at 1600°C. The HIPed SiC that was doped with boron could be deformed at a stress that was one-third lower than that of hot-pressed boron- and carbon-doped SiC with a grain size of 0.8 µm.     

Generation of nanosized optical beams by use of butted gratings with small numbers of periods

We have devised an optical high-throughput nanosized beam-generating structure consisting of butted gratings with small numbers of periods. We analyzed the structure of these grating by the transverse resonance method. We then demonstrated that it is possible to achieve a beam spot of 45 nm x 60 nm (FWHM) with this structure for the optical heads used in ultrahigh-density recording, such as those used in laser-assisted magnetic recording storage.