Development of multi‐analyte DNA microchip using 3D nanoprototyping fabrication method

The importance of microfluidics systems for high‐throughput postgenome analysis has been steadily increasing. We conceived and fabricated an integrated six‐microchip capillary electrophoresis unit on a small area of 30 × 30 mm for high‐throughput DNA analysis. The design of the structure was performed using a fluid dynamics simulation of electrophoresis to improve the DNA separation resolution. A narrow width of the micro channel at the corners was adopted. For simple fabrication of the microchip, we developed the PMMA structure of the micro fluid channel using lithography, molding, and fusion bonding techniques. It was demonstrated that the proposed integrated structure of micro channels results in good performance of on‐chip DNA separation in a small one‐unit area of 9 × 9 mm. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(1): 32–36, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21156     

Effect of electrode surface roughness on breakdown conditioning under non-uniform electric field in vacuum

Breakdown (BD) characteristics in vacuum are strongly dependent on the electrode surface conditions, such as surface roughness. However, there is little known concerning the details of the relationship between the surface roughness and BD conditioning effect. In practical application, it is important to clarify how the surface roughness affects the breakdown conditioning characteristics, especially for the non-uniform field configuration. This paper discusses the effect of surface roughness on breakdown conditioning characteristics under non-uniform electric field in vacuum under applications of negative standard lightning impulse voltage. For this purpose, we examined the BD conditioning of a rod-to-plane electrode made of SUS304 and Cu-Cr. The surface roughness of R_a is controlled from 0.3 to 2.5 mum. Experimental results revealed that the enhancement of surface roughness of electrodes increases the number of BD to complete the conditioning effect. We explained the results from the observed results of the electrode surface. Consequently, we could clarify the effect of surface roughness on the conditioning effect under non-uniform electric field in vacuum quantitatively.     

Breakdown conditioning characteristics of long gap electrodes in a vacuum

An improvement in dielectric strength is required in vacuum circuit breakers (VCBs) intended for use in higher voltage systems. In order to develop higher voltage VCBs, it is important to improve the dielectric strength in a vacuum based on consideration of the vacuum breakdown mechanism. Particularly for gaps longer than 10 mm, little is known about the breakdown mechanisms and their quantitative analyses in a vacuum. This paper discusses the breakdown conditioning characteristics of long gap electrodes, under a non-uniform electric field in a vacuum. We treat gap lengths of up to 50 mm in this paper. The conditioning characteristics are investigated under impulse voltage applications. A negative standard lightning impulse voltage was applied to rod-plane electrodes made of Cu-Cr and SUS304 for different tip radii and gap distances until the conditioning effect was completed. We observed illumination spots on electrodes at each breakdown during the conditioning process and calculated the corresponding breakdown field strengths. Experimental results revealed that the tendency of breakdowns associated with long gaps is different from that for the short gaps. As a result, we clarified that the breakdown field strengths are nearly constant at 110-120 kV/mm at the distances longer than 10 mm, and the breakdown field strength is at its maximum when the gap distance is about 5 mm.     

Genomic Instability and Cancer Risk Associated with Erroneous DNA Repair

Many cancers develop as a consequence of genomic instability, which induces genomic rearrangements and nucleotide mutations. Failure to correct DNA damage in DNA repair defective cells, such as in BRCA1 and BRCA2 mutated backgrounds, is directly associated with increased cancer risk. Genomic rearrangement is generally a consequence of erroneous repair of DNA double-strand breaks (DSBs), though paradoxically, many cancers develop in the absence of DNA repair defects. DNA repair systems are essential for cell survival, and in cancers deficient in one repair pathway, other pathways can become upregulated. In this review, we examine the current literature on genomic alterations in cancer cells and the association between these alterations and DNA repair pathway inactivation and upregulation.     

Oxytocin-Dependent Regulation of TRPs Expression in Trigeminal Ganglion Neurons Attenuates Orofacial Neuropathic Pain following Infraorbital Nerve Injury in Rats

We evaluated the mechanisms underlying the oxytocin (OXT)-induced analgesic effect on orofacial neuropathic pain following infraorbital nerve injury (IONI). IONI was established through tight ligation of one-third of the infraorbital nerve thickness. Subsequently, the head withdrawal threshold for mechanical stimulation (MHWT) of the whisker pad skin was measured using a von Frey filament. Trigeminal ganglion (TG) neurons innervating the whisker pad skin were identified using a retrograde labeling technique. OXT receptor-immunoreactive (IR), transient receptor potential vanilloid 1 (TRPV1)-IR, and TRPV4-IR TG neurons innervating the whisker pad skin were examined on post-IONI day 5. The MHWT remarkably decreased from post-IONI day 1 onward. OXT application to the nerve-injured site attenuated the decrease in MHWT from day 5 onward. TRPV1 or TRPV4 antagonism significantly suppressed the decrement of MHWT following IONI. OXT receptors were expressed in the uninjured and Fluoro-Gold (FG)-labeled TG neurons. Furthermore, there was an increase in the number of FG-labeled TRPV1-IR and TRPV4-IR TG neurons, which was inhibited by administering OXT. This inhibition was suppressed by co-administration with an OXT receptor antagonist. These findings suggest that OXT application inhibits the increase in TRPV1-IR and TRPV4-IR TG neurons innervating the whisker pad skin, which attenuates post-IONI orofacial mechanical allodynia.     

Adsorbed Atoms and Molecules Destined for a Reaction

The idea of an activation complex is popular for explaining reaction rates, but the characteristics of reactions and catalysis may not be explained in this way. A predestined state for each reaction composed of surface atoms and adsorbed species is responsible for these features. Two single Sn atoms trapped in adjacent half-unit cells of an Si(111) 7 × 7 surface is an example of a predestined state. An isolated Sn atom in a half-unit cell does not migrate to other half-unit cells at room temperature, but when two single Sn atoms are in adjacent half-unit cells they undergo rapid combination to form an Sn₂ dimer. In addition, these two single Sn atoms replace the center Si adatoms and an Si₄ cluster is formed. The spatial distribution of molecules desorbing from surfaces may reflect the predestined states for the desorption processes. The spatial distribution in the temperature-programmed desorption (TPD) of NO on Pd(110) and Pd(211) surfaces and that in the temperature-programmed reaction (TPR) of NO + H₂ were studied. N₂ desorbing from Pd(110) by the recombination of N atoms obeys cos⁶ – cos⁷ but the N₂ produced by a catalytic reaction of NO with H₂ obeys cos. In contrast, the N₂ desorbing with NO at 490 K in the TPD of Pd(110) shows a sharp off-normal distribution expressed by cos⁴⁶( – 38). The adsorption of NO on Pd(211) predominantly occurs on the (111) terrace but the spatial distribution suggests that the predestined states for the reaction and desorption are formed on both the (111) terrace and (100) step surfaces.     

Characteristics of visual feedback in postural control during standing.

In the present study, the visual feedback system in postural control was investigated. To suppress the vestibular and proprioceptive feedback paths, a subject stood on a force-measuring plate with a fixed back support. Because the subject's body was immovable under these conditions, the subject controlled a computer model which simulated body dynamics. Information on the sway angle of the model was fed visually. Under this condition, frequency response functions for the ankle moment in response to the sway angle were calculated. The experimental results suggest that the visual feedback system contains a large time delay and, consequently, the visual system does not by itself allow a subject to maintain an upright posture. Index Terms- Feedback control, frequency characteristics, identification, posture, visual sensory feedback.     

Solidification by Convective Drying of Particle Layer Wetted with Dilute Agar Gel

Solidified porous slab is formed through convective drying of glass particle layer wetted with aqueous dilute agar gel. Measured critical mean moisture content increases with increasing initial moisture or agar content. The agar gel moves in viscous flow caused by capillary pressure during drying. A new drying model based on the receding evaporation plane model is proposed. Drying period is divided into surface and internal evaporation periods. Wet slab consists of dried and wet zones during the internal evaporation period, while the wet slab consists of wet zone only during the surface evaporation period. In the new model, the evaporation rate from the wet zone in the internal drying period is estimated with the linear driving force (LDF) approximation in the field of adsorption engineering. Critical moisture content, that is, mean moisture content between the surface and internal periods, is estimated with a mass balance on the surface. Simulated results by the new drying model with reasonable fitting parameters agree very well with measured drying data.     

Ultra-sensitive high-speed density measurement of the “piston effect” in a critical fluid

In order to conduct a detailed investigation of the piston effect, the peculiar heat transportation phenomenon in critical fluids, an ultra-sensitive high-speed density measurement system was developed using a very thin heater, a sensitive interferometer and a large-capacity high-speed data acquisition system. As the first step of the investigation, an experiment was conducted to measure the velocity of sound in CO2 near its critical point. Short heat pulses suppressing the disturbance of natural convection were applied to a small cell filled with almost-critical CO2 fluid and were detected by the measurement system. Because the pulses propagated through the cell at the velocity of sound and were reflected several times between the cell walls, the velocity could be precisely determined by measuring the time intervals between successive reflections. The resulting velocity profile versus temperature showed good agreement with theoretical prediction and numerical simulations. This result validated the density measurement system, and it is considered that the measurement system will be a very effective tool for further studies on critical phenomena with the aid of numerical simulation.     

Polyether-segmented nylon hemodialysis membranes. III. Preparation and properties of new polyether-segmented nylon

In order to apply a blood-compatible polymer to hemodialysis membrane, a new polyether-segmented nylon which dissolved in common organic solvents was designed. The basic polyether-segmented nylon was synthesized by melt polycondensation from sebacic acid, m-xylenediamine, and α,ω-bisaminopropyl-poly(ethylene oxide). To improve the solubility, azelaic acid and hexamethylenediamine were copolycondensed with the basic copolymer. The solubility was correlated with the heat of fusion (ΔH_m) of the copolymer. When ΔH_m is < 30 mJ/mg, the polymer is soluble in dimethylsulfoxide and makes a stable solution. The nonthrombogenicity was investigated in the viewpoint of adhesion of platelet onto the copolymer surface. It is made clear that the surface of the block copolymer, having > 10 wt % of poly(ethylene oxide), suppresses the adhesion of platelet, and the composition of the nylon block has no effect on the adhesion of platelet. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1723–1729, 1997