利用同步辐射进行氟塑料的表面改性与微器件制造研究

It is well-known that fluorinated polymers are very unique polymer materials because of their distinguished properties, such as high electrical resistivities, chemical and thermal stabilities, bio-compatibilities, etc. However,polytetrafluoroethylene (PTFE) is degraded by ionizing radiation with a low dose through main chain scission, and the mechanical properties are seriously deteriorated. In early 1990's, it was found that irradiation for PTFE at elevating temperature enhances recombination of radicals induced by ionizing radiation. Thus, crosslinked PTFE had been obtained[1,2]. The crosslinked PTFE shows remarkable improvements for the radiation durability and mechanical properties, etc.We have performed micro-fabrication by means of synchrotron radiation (SR) for various kinds of PTFEs including crosslinked PTFEs. The direct photo--etching technique using SR is known as TIEGA() technology,which has been developed by Sumitomo Heavy Industries, Ltd. The technology was applied for the micro-fabrication of fluorinated polymers. It has been found that etching rates obtained for crosslinked PTFEs were much larger than those of the non-crosslinked. The fact is strange from the viewpoint of radiation durability of crosslinked PTFEs. Hence, the results are not described by simple consideration such as the G-values of main chain scission. We have proposed that the etching rates should be controlled by the complex mechanism through at least two different steps as polymer decomposition and fragment desorption mechanisms.On the other hand, we have found that abnormal reactions were induced at the surface region under the SR etching for the various kinds of fluorinated polymers. Through the measurements using differential scanning calorimetory (DSC) and solid state 19F-NMR, we have confirmed crosslinking reactions for the polymers even in solid states. This reaction should be induced by the very high density radicals formation and their recombination in very localized area of the polymers under the SR etching processes.     

Prediction of greenhouse gas reduction potential in Japanese residential sector by residential energy end-use model

A model is developed that simulates nationwide energy consumption of the residential sector by considering the diversity of household and building types. Since this model can simulate the energy consumption for each household and building category by dynamic energy use based on the schedule of the occupants’ activities and a heating and cooling load calculation model, various kinds of energy-saving policies can be evaluated with considerable accuracy. In addition, the average energy efficiency of major electric appliances used in the residential sector and the percentages of housing insulation levels of existing houses is predicted by the “stock transition model.” In this paper, energy consumption and CO₂ emissions in the Japanese residential sector until 2025 are predicted. For example, as a business – as-usual (BAU) case, CO₂ emissions will be reduced by 7% from the 1990 level. Also evaluated are mitigation measures such as the energy efficiency standard for home electric appliances, thermal insulation code, reduction of standby power, high-efficiency water heaters, energy-efficient behavior of occupants, and dissemination of photovoltaic panels.     

The inhibitory action of long-chain fatty acids on the DNA binding activity of p53

The in vitro relationship between human p53 DNA binding domain (p53 DBD) and FA was investigated. We found that saturated and monounsaturated long-chain FA inhibited the double-stranded DNA (dsDNA) binding activity of p53 DBD. The strongest inhibitors of saturated and unsaturated FA were docosanoic acid (22∶0) and cis-12-heneicosenoic acid (21∶1n−9), respectively. n-Octadecane, trans-unsaturated FA, and FAME had no influence on the binding activity of p53 DBD, showing that the FA structures such as one or no double bond of cis configuration, hydrocarbon chain of length C₂₀ to C₂₂, and free carboxyl groups are important for the inhibition. The inhibitory effect of the R248A mutant of p53 DBD by saturated FA was as strong as that for wild-type p53 DBD. On the other hand, the inhibition of dsDNA binding activity of the same mutant by the cis-configuration of monounsaturated FA was weaker than that for the wild type. These results suggest that R248 in p53 DBD is important for binding to monounsaturated FA. This is the first report that long-chain FA act as dsDNA binding inhibitor of p53, and it could be considered that FA in the cell membrane might regulate the activity of p53 for cell division, cell-cycle checkpoint, and tumor suppression.     

Dynamical structure of peptide molecules

In view of the importance of the peptide linkage in structural biology, we have carried out intensive investigations on peptide molecules consisting of a peptide linkage with one or two substituents in the gas phase by Fourier transform microwave spectroscopy, paying special attention to the internal rotation of the substituents relative to the central linkage framework. We have found that, in sharp contrast with the stiff structure around the central C-N bond of the linkage, the internal rotations of the substituents are of low frequency and thus of large amplitude and are extremely susceptible to their local environment such as the presence of other substituents.     

Disordered carbon negative electrode for electrochemical capacitors and high-rate batteries

In order to understand the properties of high-rate capability and cycleability for a disordered carbon negative electrode in LiPF₆/PC based electrolyte solution, the cell performance tests with various rates and depth of discharges (DODs) has been studied by spectroscopic and electrochemical analyses. From the charge-discharge measurements, a surface carbon-edge redox reaction occurring between a carbonyl (C_edgeO) and a lithium alkoxide (C_edge-OLi) that delivers a large capacity was found fast and high cycleability at only shallow DOD (2.0-0.4 V). The limited or shallow charge-discharge cycling utilizing such facile and reversible action of the C_edgeO/C_edge-OLi of the disordered carbon is suited to an application for an negative electrode of asymmetric hybrid capacitors. A deep DOD discharge (2.0-0.0 V) revealed the existence of some complex processes involving a lithium cluster deposition at pores or microvoids as well as a lithium ion intercalation at graphene layers. The cluster deposition at pores was found to be relatively fast and reproducible. The lithium ion intercalation at graphenes and the subsequent cluster deposition at microvoids were found to be slow and degrade the cycleability after 100 cycles because of the accumulation of a thick and low-ion-conductive solid electrolyte interface (SEI) film on surface.     

Effects of magnesium content in the feed on cataract development in Shumiya cataract rat

Cataract is a phenomenon in which the eye becomes opaque resulting in severe visual impairment, and senile cataract is the most common cause of blindness in the world. We investigated the effect of magnesium (Mg) supplementation on cataract development using shumiya cataract rat (SCR). The SCR were fed on either a low Mg (Mg 50 mg/kg), standard Mg (Mg 500 mg/kg), or high Mg (Mg 5000 mg/kg) diet from aged 5 to 15 weeks. The growth curve of SCRs fed on a low Mg diet was the same as that of SCRs fed on a standard diet. The growth curve of SCRs fed on a high Mg diet was significantly suppressed in comparison with those fed on a standard diet. The opacification of lenses from SCR fed on a standard Mg diet started at 11 weeks of age. The opacification of lenses from SCR fed on a high Mg diet was similar to that from SCR fed on a standard Mg diet. On the other hand, the low Mg diet accelerated the onset of cataract development, and the opacity started at 10 weeks of age. In addition, the calcium ion (Ca2+) content in SCR lenses fed on a low Mg diet significantly increased in comparison with that in lenses from SCR fed on a standard Mg diet. These results suggest that Mg deficiency causes acceleration of cataract development in SCR, probably due to a rise in the Ca2+ content in the lens.     

Extraction of Stimulus-Selective Intrinsic Optical Signals From the Cat Visual Cortex

Optical imaging based on intrinsic optical signals has been widely utilized in studies on the functional organization of various areas of the brain. Because of the small size of the optical signals and the large amount of background noise that is present, it is critical to be able to separate the stimulus-driven optical change from the background. In this study, we propose a novel method and apply it to the analysis of the orientation preference structure in cat area 17. The three criteria used to determine the activation included the amplitude of the optical change in the optical intensity, the statistical significance level of the change, and the temporal relationship between the optical change and the visual stimulation. In the activated region extracted by the new method, 82.4 ± 8.2% of the cells were electrophysiologically responsive to the stimuli that evoked the optical change. This was significantly higher than the 46.4 ± 7.1% value obtained when the activation region was extracted by the most widely used method, i.e. a differential map between two complementary stimuli, such as orthogonal orientations. Our newly proposed method provides a robust and an effective way to reduce manual operations used in the signal extraction process. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Simplified 20-µm pitch vertical interconnection process for 3D chip stacking

This paper describes a simplified vertical interconnection process for three-dimensional (3D) chip stacking. The unique feature of this new process is that the conductive filling material in the through-silicon-vias (TSVs), the microbumps, and the interconnection materials are all fabricated in one processing stage. All of the steps can be performed with the same piece of equipment. Prototype chips with 20-µm-pitch vertical interconnections have been demonstrated successfully. By using this technique, 75-µm deep high-aspect-ratio vias can be completely filled without voids using Ni electroplating and uniform 20-µm-pitch microbumps that are 4-µm tall have been fabricated using Sn-Cu electroplating. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Application of elastic salmon collagen gel to uniaxial stretching culture of human umbilical vein endothelial cells

In this study, we investigated the potential of an elastic salmon collagen gel (e-gel) for use as stretching culture scaffold. First, human umbilical vein endothelial cells (HUVECs) were cultured on the e-gel under static condition, and their growth was evaluated by DNA content measurement, MTT test, and scanning electron microscopy. The results demonstrated steady increases in cell number with culture time. Next, HUVECs were cultured on the e-gel under static condition for 2 d, then uniaxially stretched at a constant frequency (10% elongation at 1 Hz). After the stretching culture for 2 h, the cells oriented perpendicularly to the stretch direction. Moreover, the interleukin-6 and interleukin-8 productions of the cells significantly increased under the stretch condition compared with those under the static condition. These results were in good agreement with the published data in which an elastic silicone membrane was used as a scaffold. In conclusion, the e-gel can be used for stretching culture for vascular tissue engineering.