Laboratory performance study of the quantitative detection method for genetically modified soybeans (roundup ready soybeans 40-3-2)

To investigate important factors affecting the analytical results, a laboratory-performance study was attempted for the Japanese official methods to detect genetically modified (GM) soybeans (40-3-2). Test samples containing 0, 1 and 5% GM soya powder in non-GM soya powder was prepared. A set of 3 test samples was sent to the participating laboratories along with the protocol. The data were collected from all laboratories and statistically analyzed. In the real-time PCR detection method, the average values of the GM 1% and 5% samples were both much lower than the spiked value because the laboratories using a silica-membrane DNA extraction method underestimated the GM value. On the other hand, the laboratories using other extraction methods, such as the CTAB method obtained values close to the spiked value. These results suggest that use of the silica-membrane DNA extraction method may result in underestimation of the GM content in the real-time PCR method. In the ELISA method, the average value of 5% spiked samples appears to be slightly higher than the fortified value. But, overall, it was considered that reported values were close to the spiked level.     

Tunable spin polarization in bismuth ultrathin film on Si(111)

We performed a spin- and angle-resolved photoemission spectroscopy of bismuth ultrathin film on Si(111) with various film thickness d. We found that the spin polarization of spin-split Rashba surface states near the Brillouin-zone boundary, which is high (0.7) at d = 40 BL (bilayers), is gradually reduced on decreasing d and almost vanishes at d = 8 BL. This finding provides a novel method to generate spin-polarized electrons with tunable spin-polarization.     

Longwave radiation flux from an urban canopy: Evaluation via measurements of directional radiometric temperature

Longwave radiation flux, an important part of the surface heat budget, is generally represented by εσT_r⁴, where ε is the surface emissivity, σ is the Stefan-Boltzmann constant, and T_r is the measured radiometric temperature. εσT_r⁴ differs from hemispheric emission because the measured radiometric temperature is anisotropic for an uneven surface. This paper analyzes the anisotropy-related error in measurements of longwave radiation flux from a building canopy. The flux difference between εσT_r⁴ and directly measured flux was up to 8% of the directly measured flux, which could be greater than the typical error in measurement of turbulent heat flux over a building canopy. The flux difference increased as the temperature variation within the urban street canyon increased, and also with increasing difference between the incident solar radiation of the building walls and street canyon floors (pavement, roads, ground surface). Theoretical calculations indicate that the flux difference is due to the structure of the building canopy and the temperature difference between the walls and canopy floors. A numerical model of a building canopy heat budget shows that the flux difference increases as the street canyon aspect ratio increases.     

Mutual adaptation among man and machine by using f-MRI analysis

A prosthetic device for disabled people requires new and reliable robotics technology. This paper describes the interesting reaction of our brain to an adaptable prosthetic system. The adaptable prosthetic system is composed of an EMG signal controlled robot hand with an EMG pattern recognition learning function for Transradial (below elbow) prostheses. The mutual adaptation between the system and the human body is analyzed using functional magnetic resonance imaging (f-MRI) in order to clarify the plasticity of the motor and sensory cortex area according to the changes in the prosthetic system. The developed prosthetic hand has 13 DOF: three motors on the thumb, two motors for each finger, and two motors for the wrist. The tactile feedback is applied by using surface electrical stimulus. The f-MRI data shows the process of replacement from a phantom limb image to the prosthetic hand image.     

Strain effects and phase separation tendency in highly strained La0.7Ba0.3MnO3 thin films on LaAlO3 substrates

The magnetic and transport properties of epitaxial La_0.7Ba_0.3MnO₃ films on LaAlO₃ substrates have been investigated and compared with those on SrTiO₃ substrates. It is found that the ferromagnetic and metallic transition temperature of the highly compressive strained films on LaAlO₃ substrates decreases steadily with decreasing film thickness, while it changes little in the lightly strained films on SrTiO₃ substrates. The properties of the films on LaAlO₃ substrates are more sensitive to a post-annealing procedure. A tendency to phase separation, which induces a difference between the insulator-metal transition temperature T_MI and the Curie temperature T_C, is observed for the films with a medium oxygen annealing process. We argue that the phase separation is due to both the highly compressive strain and oxygen deficiency in the films.     

Inter-laboratory evaluation studies for establishment of notified ELISA methods for allergic substances (buckwheat)

Inter-laboratory evaluation studies were conducted for the ELISA methods for allergic substances (buckwheat). Extracts of snack, bun and udon spiked with buckwheat standard protein at a level of 5-20 ng/mL as sample solutions were analyzed in replicate at 10 laboratories. Coefficients of variation (CVs) of the ELISA methods using a Buckwheat Protein ELISA Kit (Buckwheat kit) and a FASTKIT Buckwheat ELISA kit (Buckwheat ELISA kit) were mostly below 10%. Mean recoveries of the buckwheat standard protein from the food extracts were over 40% in the two ELISA methods. Repeatability relative standard deviations of buckwheat standard protein in three food extracts were in the ranges of 6.8-78.5% and 5.0-33.9% for the Buckwheat kit and the Buckwheat ELISA kit, respectively. Reproducibility relative standard deviations of buckwheat standard protein in three food extracts were 11.9-69.5% and 16.5-34.1% for the Buckwheat kit and the Buckwheat ELISA kit, respectively. The detection limits of both ELISA methods were 1 ng/mL in sample solutions. These results suggest that the notified ELISA methods are reliable and reproducible for the inspection of buckwheat protein levels in extracts of snack, bun and udon.     

Determination method of tricresyl phosphate in polyvinyl chloride

A simple and rapid method using HPLC was developed for the determination of tricresyl phosphate (TCP) in polyvinyl chloride (PVC) articles. A test sample was extracted with acetonitrile at 37 degrees C overnight. The extract solution diluted with an equivalent amount of water was applied to a Sep-Pak C18 cartridge, and TCP was eluted with acetonitrile-water (2:1) mixture. The eluate was analyzed by HPLC with an Inertsil Ph-3 column, using 65% acetonitrile/water as the mobile phase, with UV detection (264 nm). The calibration curve was rectilinear from 0.5 to 100 micrograms/mL. The recoveries of TCP added to various kinds of PVC articles at the level of 1,000 micrograms/g were 84.7-98.6%. The determination limit of TCP was 50 micrograms/g in samples. This method was applied to products including 3.1, 6.6 and 8.8% TCP and the recoveries of TCP were 87.3-91.4%. This method is very simple, and it seems suitable for a regulatory test.     

Determination of methanol in gardenia red and gardenia blue

The natural food color gardenia red is manufactured through the hydrolysis of the methyl ester of iridoid glucoside. Gardenia blue is also made from iridoid glucoside. Therefore, there is a possibility that the commercial products contain methanol. To determine methanol in gardenia red and gardenia blue, a headspace GC method with standard addition was developed. In the case of gardenia blue with the methyl ester, methanol may be formed during the analytical procedures for methanol. Thus, conditions in which methanol would not be produced in the headspace-GC method were investigated. Vials containing 1 g of the color preparation, 1 mL of water, and a standard solution were sealed. Equilibrium temperature was an important factor among the conditions for analyzing methanol in gardenia blue. Although at room temperature and 50 degrees C, the contents of methanol were equal, the content increased 1.2 times at 80 degrees C. Methanol contents determined at 50 degrees C were 8 and 9 micrograms/g in two gardenia red products and 25-34 micrograms/g in three gardenia blue products, which were below the residual limit of 50 micrograms/g set for many other natural food additives.     

Analysis of trans-fat levels in total diet and one-serving samples using the verified GC-method and estimation of the intake in Japan

In Japan, discussions on the regulation and labeling of trans-fat (TF) have under way for several years in the Food Safety Commission and the Consumer Affairs Agency. However, administrative measures for TF have not yet been taken, partly because of the insufficiency of scientific data in Japan. To provide data about the TF intake by Japanese, we determined the levels of TF contained in total diet samples and in food samples that were served as individual meals (one-serving samples). We analyzed 5 groups of total diet samples prepared in 11 regions throughout Japan, and 5 categories of one-serving samples using the GC-method after verifying its performance. The estimated daily intake of TF based on the analytical results of the total diet samples was around 500 mg and no significant difference was observed in the intake of the TF among the 11 surveyed regions. On the other hand, many one-serving samples classified into "hamburger", "pizza" and "Western food" categories contained more than 500 mg of TF per serving, the standard value in the labeling regulation in the United States. If these one-serving meals are taken to represent one meal out of 3 in a day, the intake of TF can easily be expected to exceed the daily intake estimated through the analysis of the total diet samples.