Multi-probe scanning system comprising three laser interferometers and one autocollimator for measuring flat bar mirror profile with nanometer accuracy

This paper describes a multi-probe scanning system comprising three laser interferometers and one autocollimator to measure a flat bar mirror profile with nanometer accuracy. The laser interferometers probe the surface of the flat bar mirror that is fixed on top of a scanning stage, while the autocollimator simultaneously measures the yaw error of the scanning stage. The flat bar mirror profile and horizontal straightness motion error are reconstructed by an application of simultaneous linear equations and least-squares method. Measurement uncertainties of the flat bar mirror profile were numerically evaluated for different installation distances between the laser interferometers. The average measurement uncertainty was found to be only 10 nm with installation distances of 10 and 21 mm between the first and second, and first and third interferometers, respectively. To validate the simulation results, a prototype system was built using an X–Y linear stage driven by a stepper motor with steps of 1 mm along the X direction. Experiments were conducted with fixed interferometers distances of 10 and 21 mm, as in the simulation, on a flat bar mirror with a profile known to an accuracy of λ = 632.8 nm. The average value of two standard deviations (95%) of the profile calculated over ten experiments was approximately 10 nm. Other results from the experiment showed that the system can also measure the yaw and horizontal straightness motion errors successfully at a high horizontal resolution. Comparing with the results measured by ZYGO's interferometer, our measured data excluding some edge points showed agreement to within approximately 10 nm. Therefore, we concluded that our measurement profile has an accuracy in the nanometer range.     

A photovoltaic cell from p-type boron-doped amorphous carbon film

Boron-doped amorphous carbon (a-C(B)) films were prepared on n-type silicon using pulsed laser deposition technique of a graphite target. The a-C(B) films have been proved to be p-type by the formation of a heterojunction between the a-C(B) film and n-Si. The device of a-C(B)/n-Si structure yielded an open-circuit voltage (V_oc) of 0.27 V and a short-circuit current density (J_sc) of 2.2 mA/cm² under illumination (AM1.5 100 mW/cm²). According to calculation, the energy conversion efficiency and fill factor were found to be about 0.3% and 0.53, respectively.     

Adsorption of tetrakis(p-sulfonatophenyl)porphyrin on kaolinite

The surface modification of kaolinite to introduce the adsorption sites for anionic species was reported. The introduction of an anion exchange site was as follows; intercalation of 2-aminoethanol into kaolinite by using dimethyl sulfoxide-kaolinite intercalation compound as a precursor and subsequent hydrochlorination of 2-aminoethanol-kaolinite in 1,4-dioxane. The hydrochlorination of 2-aminoethanol-kaolinite was confirmed by the increase in the basal spacing (0.2 nm, corresponding to the diameter of chlorine) and the appearance of the infrared absorption bands due to ammonium groups. The modified kaolinite adsorbed an anionic dye, tetrakis(p-sulfonatophenyl)porphyrin, from a N,N-dimethylformamide solution. Initial slope of the adsorption isotherm of tetrakis(p-sulfonatophenyl)porphyrin on the hydrochlorinated 2-aminoethanol-kaolinite was steep, showing strong adsorbate-adsorbent interactions. The gallery height after the adsorption of tetrakis(p-sulfonatophenyl)porphyrin was close to the thickness of the porphyrin ring, suggesting that tetrakis(p-sulfonatophenyl)porphyrin was intercalated as a monomolecular layer and that chlorine simultaneously deintercalated.     

Theoretical analysis of the tensile strength of a powder bed

The authors have proposed an experimental equation which correlates the tensile strength of a powder bed measured by split cell methods with the porosity of a powder bed. In this report, the authors discuss the relationships between the porosity and the pre-compressive stress and also between the tensile strength and the pre-compressive stress. As the results of this discussion, the physical base of the proposed experimental equation is proved theoretically.Furthermore, it has also been proved that the pre-compression of a powder bed brings not only the decrease of the porosity but also the increase of compressive force at the contact point of particles, and therefore the increase of tensile strength by increasing the-compression force cannot be explained simply by the change of the porosity, and then another factor, such as the compressive force at the contact point, must be considered.     

Characterization of single quantum wells on GaAs/Si grown bymetalorganic chemical vapor deposition

The use of Al_0.5Ga_0.5As/Al_0.55Ga _0.45P intermediate layers and in-situ thermal cycle annealing are shown to be effective in obtaining smooth and sharp heterointerfaces for Al_0.3Ga_0.7As/GaAs single quantum wells (SQWs) grown on Si substrates, as a result of an initial two-dimensional growth and a reduction in threading dislocation density. The best lasing characteristics are obtained in Al_0.3Ga_0.7As/GaAs SQW laser diodes fabricated using the above structure in comparison to those fabricated using the more conventional two-step growth technique     

Interference of free fatty acids from the hepatopancreas of mussels with the mouse bioassay for shellfish toxins

Determination of free fatty acids (FFA) in hepatopancreas of mussel,Mytilus coruscus, contaminated by diarrhetic shellfish poisoning (DSP) toxins, was carried out by high-performance liquid chromatography-fluorometry as their 9-anthryldiazomethane derivatives. The FFA in the hepatopancreas of mussels during May 30–June 14 were 443–666 μg/g. A marked increase in FFA content was observed on June 20 (2197 μg/g hepatopancreas) and June 27 (6322 μg/g hepatopancreas). The proportion of polyunsaturated fatty acids (PUFA), including 20∶4n–6, 20∶5n–3, and 22∶6n–3, in mussel FFA increased during the experimental period. Diatoms almost completely dominated the phytoplankton community at the experimental site, suggesting that diatoms were the origin of the PUFA accumulated in mussels. The toxicity of FFA in mussel hepatopancreas on June 27 was sufficiently high as to interfere with the mouse bioassay by injection of an extract of shellfish, the official method for DSP toxin analysis.     

Characterization of texture and mechanical properties of heat-induced soy protein gels

Heat-set gels were prepared from acid-precipitated soybean proteins at various heating temperatures (80–100°C), protein concentrations (18–20%), and proportions of glycinin. The gels were evaluated for mechanical parameters by means of a compression-decompression test. Gels formed at higher heating temperature and protein concentration were firm, tough and unfracturable. The elasticities of the gels were similar at all protein concentrations and were lower when heated at higher temperature. Heating above 93°C was necessary for formation of rigid gels. The glycinin/β-conglycinin ratio affected the texture of the gels. Three-dimensional representation of the gels through factor analysis of instrumental data and calculation of factor scores was useful to evaluate the texture of the gels.     

200 Channel Semiconductor Detectors for X-Ray Computed Tomography

Prototype 200 channel semiconductor detectors for third generation X-ray computed tomography have been developed using surface-barrier diodes fabricated from high-purity n-type silicon. The image reconstruction test was successful, and the relationship between the image quality and the detector characteristics has been studied.