Microfluidic chip toward cellular ATP and ATP-conjugated metabolic analysis with bioluminescence detection

In this article, a microfluidic platform integrating capillary electrophoresis and bioluminescence (BL) detection that was fabricated in poly(dimethylsiloxane) (PDMS) with lab-on-a-chip technology was demonstrated for cellular metabolic analyses. A microchannels network, "cross combining with Y", was designed to perform on-chip sample preparation, separation, and BL detection of ATP and ATP-conjugated metabolites, using firefly luciferin-luciferase BL system. A dynamic modification of the channel wall of PDMS proved to be crucial to reverse the direction of electroosmotic flow (EOF), which was uniquely achieved by a prewash cycle with a cationic surfactant didodecyldimethylammonium bromide. The influences of surfactant on the EOF and BL reaction were also investigated. Quantitative analyses revealed a dynamic linear range over 2 orders of magnitude for ATP, with a detection limit down to submicromolar (midattomole). The method was validated by measuring cellular ATP of E. coli. with direct on-chip cell lysis. Further work was emphasized on ATP-conjugated metabolite analysis, using galactose as an example. Assays of galactose in human urine samples confirmed the reliability of the protocol, which revealed good prospect of this platform for ATP-conjugated submetabolomic profiling.     

Cortical speech processing mechanisms while vocalizing visually presented languages

To elucidate cortical processing during vocalization, we used positron emission tomography to measure regional cerebral blood flow during vocalization in six Japanese subjects. During reading Japanese sentences used daily or short syllables aloud, the visual cortices, the left Heschl's gyrus, Broca's area, the primary motor area of the articulatory organs, the supplementary motor area and the cerebellum were significantly activated, compared with resting conditions. The superior temporal gyri were rarely activated. Significant activation of the cerebellum was observed by comparing cortical activity during reading sentences used daily with that during reading meaningless short syllables. These results suggest that vocalization of familiar materials is taken over by the cerebellum, rather than cortical speech areas, and without engagement of the superior temporal gyri.     

Temperature dependence of impact fracture energies of short glass fiber–epoxy and unsaturated polyester composites

The temperature dependence of the impact fracture energies of composites reinforced with random-planar orientation of short fibers was studied theoretically and experimentally. The theoretical values of the impact fracture energy of these composites is described by the sum of the fracture energy of the matrix and the fibers and the energy necessary to pull out the fibers on the crack surface, taking into consideration the temperature dependence of the critical fiber length and the breaking probability of fibers. The impact fracture energies were studied experimentally for epoxy and unsaturated polyester resins reinforced with random-planar orientation of short glass fibers. The theoretical values of the impact fracture energy were in good agreement with the experimental values. It was found that in any composite, the impact fracture energy of the fibers in a composite mainly contributes to the impact fracture energy of the composite at room temperature. At higher temperatures, fiber pull-out energy is more significant.     

Measurements of effective dielectric permittivity of microstrip-line-type liquid crystal devices using inductive coupled ring resonator

The effective dielectric permittivity of microstrip-line-type liquid crystal devices was determined in the 3-33 GHz frequency range by using a newly developed inductive coupled ring resonator. The frequency performance of /spl epsiv/'/sub /spl par// and /spl epsiv/'/sub /spl perp// can be obtained from the measured and simulated resonant frequencies of an inductive coupled ring resonator with or without a DC electric field E/sub 0/.     

Driver-compatible steering system for wide speed-range path following

This paper presents a method of realizing driver-compatible steering systems in ITS, for vehicles that have capabilities of carrying out path following tasks. The method aims to maintain steering smoothness from high to low vehicle speed, including nonhighway environments, which may involve tighter turns. Multiple look-ahead points are introduced, which allows to guide the vehicle with minimum steering corrections, while maintaining the tracking accuracy. The look-ahead points, one for recognizing the path deviation for the error-cancel feedback control and the other for predicting the necessary steering for feedforward control, are varied independently according to vehicle speed. This appropriately distributes the controls and determines the final output of the steering system. The look-ahead distance for feedforward is extended longer than the look-ahead distance for feedback at low velocities, and is shortened according to velocity increase. The look-ahead distance for the feedback acts the opposite. The steering control system was implemented onto an experimental vehicle and tests were conducted. The results of path following experiments show that the method is capable of realizing smooth steering control when tracking paths involving various turns, in a wide speed range, while maintaining tracking accuracy.     

Estimation Method for Liquidus Temperature of Lead-Free Solder Using Differential Scanning Calorimetry Profiles

It is usually complicated to analyze the liquidus temperature of lead-free solder, because unlike Sn-Pb eutectic solder, supercooling easily occurs during the cooling process of lead-free solder, and common lead-free solders contain only a small fraction of a primary phase. In order to determine the melting temperature range of lead-free solder easily, an estimation method using differential scanning calorimetry (DSC) profiles is proposed. The purpose of this study is to show the applicability of the newly proposed DSC-based approach. DSC profiles using several heating rates were measured and analyzed. As a result, it was found that the extrapolated onset temperature, the peak temperature, and the extrapolated end temperature of the endothermic peak were proportional to the square root of the DSC heating rate. For lower heating rate, the temperature–axis intercept of the relationship between the square root of the heating rate and the peak temperature can be regarded as the liquidus temperature under equilibrium conditions with better accuracy. For higher heating rate, the temperature–axis intercept of the relationship between the square root of the heating rate and the extrapolated end temperature can be approximately estimated as the liquidus temperature of noneutectic lead-free solder under equilibrium conditions.     

X—Y坐标平面的位置协调最优预见控制

在已知X—Y坐标平面的位置目标信号时,利用X轴坐标和Y轴坐标的位置协调关系,提出了一种X—Y坐标平面的位置协调最优预见控制方法。通过对具体的X—Y工作台的计算机仿真和实验研究,证实了该控制方法的有效性,改善了平面位置的跟踪响应特性,使在X—Y坐标平面上可获得较高的位置精度。     

Equivalence in Harmonics Between Cycloconverters and Bridge Converters

The similarity between a six-pulse three-phase cycloconverter operating in the circulating current-free mode and a six-pulse three-phase bridge converter is discussed analytically with regard to the rms value and the harmonics of the respective output voltages. A method is presented for calculating the rms voltage of a family of sideband frequencies which are generated in the output voltage of the cycloconverter. The results obtained from the analysis help to predict the amplitudes of subharmonics and beat frequencies with the cycloconverter and are essential for the design of the output filters. Analytical results are verified by comparison with those of experiment and digital computer simulation.     

Fabrication of high precision microstructure using ICP etching for capacitive inclination sensor

Capacitive inclination sensors have the advantage because it could easily provide a linear analog output with respect to inclination. Since the dimensions of the sensing region are very small, then this sensor is expected to be widely used in fields where efficient and reliable position control is a primary factor to be considered if this sensor could be mass produced at low cost. Therefore, we proposed fabrication process based on transfer to resin using mold. We successfully fabricated a micro capacitive inclination sensor by a combination of a resin forming method and a mold. The sensor consists of a gap distance of 80 μm between its electrodes. The sensor detects difference of capacitance, which varied with movement of silicone oil accompanying with inclination. When the sensor was inclined, linear analog output was obtained within the range of ?45 to +45°