Determination of β-carotene in plasma,blood cells and buccal mucosa by electrochemical detection

The β-carotene concentrations in plasma, blood cells and buccal mucosal cells were determined by high-performance liquid chromatography with electrochemical detection. This method was 1,000 times more sensitive than the conventional spectrophotometric method. Polymorphonuclear cells and red blood cells had lower β-carotene levels than the other cells. After oral administration of 580 mg/day of all-trans β-carotene to human male volunteers for a week, the β-carotene concentrations in all cell types increased at least several times above the original levels.     

Current and potential characterization on InAs nanowires by contact-mode atomic force microscopy and Kelvin probe force microscopy

We fabricated InAs nanowires on GaAs giant step structures, and studied their surfaces by two methods; one was current detection by contact-mode atomic force microscopy, and the other was surface potential measurement by Kelvin probe force microscopy (KFM). In the current detection method, the regions where the large current flowed were distributed along the step edges, and these regions agreed well with the expected distribution of InAs. This result confirms that the InAs nanowires were formed along the GaAs giant step edges. The KFM measurements showed that the potential value became more negative along each step edge, where the InAs nanowire was expected to be formed. The surface potential of the InAs nanowires is more negative than that of the surrounding GaAs, which may result from the electron accumulation in the InAs nanowires.     

Tip-to-sample distance dependence of an electrostatic force in KFM measurements

In most scanning probe methods like an atomic force microscopy, a cantilever is mechanically vibrated in order to obtain topographies. Therefore, a tip-to-sample distance periodically changes during the scanning. Since the electrostatic force, which is a long-range force, is used for potential feedback in Kelvin probe force microscopy (KFM), such mechanical vibration leads to the fluctuation of the electrostatic force between the tip and the sample. In this study, firstly, we performed two-dimensional simulations of the electric fields between surfaces of the tip and the sample and evaluated the tip-to-sample distance dependence of the electrostatic force. Secondly, we experimentally confirmed the existence of the fluctuation of the electrostatic force and the tip-to-sample distance dependence of the electrostatic force was evaluated. Both the simulations and the experiments on the tip-to-sample distance dependence showed the importance of considering the tip sidewall effect in the KFM potential determination.     

Hydrogen concentration in water from an Alkali–Ion–Water electrolyzer having a platinum-electroplated titanium electrode

The supersaturated concentration of hydrogen in electrolyzed water obtained from a flow-type electrolytic cell was studied under various electrolysis conditions. The degree of supersaturation was found to decrease as the solution supply rate to the cell increased. The ratio of observed hydrogen concentration to the theoretical hydrogen concentration obtained from the electrochemical equivalent, as calculated from the transfer of charge in the cell, was found to increase with the solution supply rate. The concentration of hydrogen in solution has a maximum at a current density of approximately 0.3 A dm^–2. This maximum was found to be independent of the flow rate, indicating that the hydrogen concentration is related to both the diffusion of dissolved hydrogen from the electrode surface to the bulk solution and hydrogen bubble growth.     

Thermionic emission model for contact resistance in organic field-effect transistor

Injection mechanism of top-contact pentacene field-effect transistor (OFET) was investigated in respect to the internal field. The contact resistance was evaluated by the transmission line method for various applied external voltages as well as various pentacene film thicknesses. The behaviour of contact resistance was described in terms of the thermionic emission model (Schottky injection) and internal electric field generated by excess charges accumulated on pentacene–gate insulator interface. It was shown that pentacene film thickness changes the internal electric field affecting the carrier injection barrier. It was concluded that the space-charge field effect made a significant contribution for smaller pentacene film thicknesses and therefore in accordance to the thermionic model was able to decrease contact resistance representing the potential drop.     

FEM analysis for hot rolling process of AM60 alloy

The rolling of AM60 sheets for 50%reduction was analyzed with DEFORM to investigate the hot deformation process. The simulated results show that the sheet velocities at the entrance(21 mm/s) and at the exit(37 mm/s) are less and larger than roll velocity,respectively.From the entrance to the neutral point,the velocity at the sheet surface is greater than that at the middle point of sheet in thickness,while that from the neutral point to the exit shows the opposite pattern.The effective strain of the shee...     

Nanostructure and High Thermoelectric Performance in Nonstoichiometric AgPbSbTe Compounds: the Role of Ag

High-performance nanostructured Ag_1−x Pb_22.5SbTe₂₀ thermoelectric materials have been fabricated using mechanical alloying and spark plasma sintering. A decrease in Ag content causes a great reduction in thermal conductivity and a prominent increase in ZT value. A minimum thermal conductivity of 0.86 W/m K and a high ZT value of 1.5 (700 K) have been obtained for the Ag_0.4Pb_22.5SbTe₂₀ sample. The smaller and denser nanoscopic regions with reduced Ag content are thought to enhance phonon scattering, resulting in decreased thermal conductivity and enhanced thermoelectric performance.     

Performance analysis design

Control of an output value y when it is a function of various variables such as A, B, is usually achieved by controlling those causes A, B. After discussing methods using partial derivatives and Monte-Carlo, which are either inaccurate or inefficient, the use of orthogonal arrays, and the use of analysis of variance for the data calculated or conducted by the arrays, are proposed in this paper as these methods have no such defects. A live example taken from an electric circuit used for a colour T.V. set is used for the explanation.     

Heavy metals removal from automobile shredder residues (ASR)

The fate of heavy metals during a separation process for automobile shredder residues (ASR) was investigated. A washing method to remove heavy metals from the ASR was also investigated. Although the separation process was not designed for removal of heavy metals, but for the recovery of reusable materials, the heavy metal content in the ASR was efficiently decreased. The concentrations of Pb, Cr and Cd in ASR were effectively reduced by a nonferrous metals removal process, and the As concentration was reduced by the removal of light dusts during the separation process. Five heavy metals (As, Se, Pb, Cr, Cd) remaining in the ASR after the separation process satisfied the content criteria of the Environmental Quality Standards for Soil (EQSS), while the concentrations of As, Se, Pb in the leachate from the remaining ASR did not satisfy the elution criteria of the EQSS. After additional washing of the remaining ASR with a pH 1 acid buffer solution, the As, Se, and Pb concentrations satisfied the EQSS for elution. These results indicate that an ASR residue can be safely recycled after a separation process, followed by washing at acidic pH.