Chemical-Labeling-Assisted Detection of Nucleobase Modifications by Quantum-Tunneling-Based Single-Molecule Sensing

Quantum-tunneling-based DNA sensing is a single-molecule technique that promises direct mapping of nucleobase modifications. However, its applicability is seriously limited because of the small difference in conductivity between modified and unmodified nucleobases. Herein, a chemical labeling strategy is presented that facilitates the detection of modified nucleotides by quantum tunneling. We used 5-Formyl-2′-deoxyuridine as a model compound and demonstrated that chemical labeling dramatically alters its molecular conductance compared with that of canonical nucleotides; thus, facilitating statistical discrimination, which is impeded in the unlabeled state. This work introduces a chemical strategy that overcomes the intrinsic difficulty in quantum-tunneling-based modification analysis—the similarity of the molecular conductance of the nucleobases of interest.     

Comprehensive evaluation of antioxidant activity for various substances with 5-axe cobweb chart

Antioxidant activities of various substances against peroxynitrite and peroxyl radical generated from 2,2′-azobis (2-methylpropionamidine) dihydrochloride (AAPH) were evaluated by the previously proposed method [Terashima, M., Nakatani, I., Harima, A., Nakamura, S., & Shiiba M. (2007). New method to evaluate water-soluble antioxidant activity based on protein structure change. Journal of Agricultural and Food Chemistry, 55(1), 165–169] using myoglobin as a probe. Activities of several antioxidants against five different reactive oxygen species, DPPH, hypochlorite ion, hydroxyl radical, peroxynitrite, and peroxyl radical, were characterised comprehensively by 5-axe cobweb charts. For example, Trolox, ascorbic acid, and ferulic acid show similar activities against DPPH radicals (7–10 mM VC), the shapes of the 5-axe cobweb charts are different from each others. This clear-cut expression would be useful to predict probable physiological effects of various antioxidants and to compare quality of antioxidants contained in food materials and food products.     

Requirements for large‐sized high‐resolution TFT‐LCDs

Abstract— A 22‐in. prototype TFT‐LCD with a resolution of 200 pixels per inch and wide‐viewing‐angle capability has been developed and its requirements in terms of screen quality and technology will be discussed. An in‐plane‐switching mode with dual‐domain structure, post‐spacers, and high‐resolution process were implemented to achieve superior front‐of‐screen quality. And, also, in order to improve reliability and productivity, we developed a new injection method for liquid crystals which enabled us to eliminate injection holes.     

On the thermal field of a wall plume (The response to artificial disturbances)

Experimental investigations were carried out on the characteristics of the thermal field of a wall plume ascending from a horizontal line heat source embedded on the low part of a vertical wall surface. For the stability analysis of the present wall plume field, a vibrating copper wire was set horizontally near the line heat source in the field and the wall plume field was disturbed by the vibrating wire. Some two-dimensional sinusoidal thermal disturbances were introduced into the wall plume field and the growth or diminution of the amplitude of temperature fluctuations by the artificial disturbance were measured in the wall plume field with a thermal probe. The response characteristics of the wall plume field to the disturbance frequency were also examined. As a result, it was ascertained that the frequency response of a wall plume field could be predicted by linear stability analysis. © 1999 Scripta Technica, Heat Trans Asian Res, 28(7): 559–572, 1999     

Removal of low-density lipoprotein from plasma by adsorption increases bradykinin and plasma nitric oxide levels in patients with peripheral atherosclerosis

Low-density lipoprotein (LDL) adsorption using a dextran sulfate cellulose column is brought about by electrostatic binding between the positive charges of apolipoprotein B in LDL and the negative charges of dextran sulfate cellulose. There is general agreement that the initial contact phase in the coagulation pathway may be activated by a negatively charged surface such as dextran sulfate cellulose, resulting in the generation of bradykinin. We investigated whether the increase in the generation of bradykinin during LDL adsorption is accompanied by the activation of endogenous production of nitric oxide (NO) in patients with peripheral atherosclerosis. LDL adsorption therapy was repeated ten times over a period of 3 months in ten peripheral atherosclerosis patients. Treatment significantly reduced serum total cholesterol and LDL cholesterol levels. This was associated with a significant improvement in Fontaine's classification and ankle pressure index. We also measured the kinin-kallikrein system and plasma levels of NO in the same patients. The results showed that coagulation factors of the intrinsic pathway including high-molecular-weight kininogen and prekallikrein decreased markedly after initial adsorption compared with the levels before treatment. There was a marked increase in bradykinin and NO concentrations after the initial adsorption, compared with their levels before adsorption. Our results suggest that the generation of bradykinin and increased plasma levels of NO may contribute to the improvement in peripheral circulation after LDL adsorption in peripheral atherosclerosis patients.     

A novel hermetic‐sealing material for FEDs

Abstract— An hermetic‐sealing material for FEDs composed of thermosetting polyimide and glass fiber, has been developed. The main backbone and end‐capping material of polyimide were investigated to satisfy both high Tg and high flowability. A thermosetting function, 4‐phenylethynylphthalic anhydride (PEPA), was used as the end‐capping material. The fracture of a rigid and softening structure was optimized in the main polymer structure. The obtained polyimide demonstrated both a high Tg (265°C) and low viscosity (98 Pa‐sec at a sealing temperature of 350°C). In order to improve the gas permeability and the mechanical and thermal characteristics of the sealing material, a mixture of various types of ceramic fillers and polyimide has been investigated, and glass fiber was adopted. When 30 wt.% of glass fiber was combined when the developed polyimide, the Ar permeability and coefficient of thermal expansion of the sealing material decreased to below one‐half of the base polyimide. This material enables us to seal at a temperature of about 350°C in nitrogen atmosphere and shows superior performance suitable for glass‐to‐glass sealing.     

Electrical communication between glucose oxidase and electrodes mediated by phenothiazine-labeled poly(ethylene oxide) bonded to lysine residues on the enzyme surface

A series of glucose oxidase (GOx) hybrids (GOx-phe-nothiazine-labeled poly(ethylene oxide) (PT-PEO)) capable of direct electrical communication with electrodes is synthesized by covalently modifying PT-PEO to lysine residues on the enzyme surface. The length of the PEO chain and the number of PT groups are systematically altered. After the PT-PEO modification, all the hybrids maintain more than 50% of enzyme activity relative to that of native GOx, although loss of the activity becomes greater with increasing PEO chain length. The catalytic current, i(cat), is observed at a potential more positive than 0.55 V after the addition of glucose, due to the intramolecular electron transfer (El) from reduced forms of flavin adenine dinucletide (FADH2/FADH) to PT+ that are electrogenerated at the electrode. The i(cat) value increases with the number of PT groups, indicating that most of the modified PT groups act as mediators. The magnitude of the i(cat) increase depends on the PEO chain length and reveals a maximum for PT-PEO with the molecular weight of 3,000. In contrast, the i(cat) is almost constant for GOx-2-(10-phenothiazyl)propionic acid (PT-PA) hybrids with more than two PT groups synthesized by covalently modifying PT-PA to surface lysines, indicating that only a few key PT groups function as mediators. The maximum rate constant (130 s(-1)) for the ET from FADH2/FADH to PT+ is obtained for the GOx hybrid modified with five PT-PEO groups with the molecular weight of 3,000.     

Dynamic structures of motor proteins myosin and kinesin, and switch protein troponin as detected by SDSL-ESR

We have studied biological nano-machines, motor and switch proteins operating as supramolecular complexes by electron spin resonance (ESR) and found key features of their molecular movements. In all the systems, the specific movements of elements or domains were detected and quite dynamic at nanometer scale. We have observed two broad but distinct orientations, separated by a 25 degrees axial rotation, of a spin label attached specifically to the light chain (LC) domain of myosin motor in the muscle fibers. The distribution became only narrower upon muscle activation. ESR spectrum from the spin label of the neck-linker of dimeric kinesin motor consisted of immobilized and mobilized components and did not exhibit nucleotide-dependent mobility change. The distance between two labels of kinesin dimer was also measured by spin dipole-dipole interaction, showing a broad distribution and a nucleotide-dependent change on the nanometer scale (>1.5 nm). These results suggest that two LC domains of myosin and two neck linkers of kinesin play a similar role for sliding movement using two conformations. The spin label of the skeletal (Tn)-I regulatory domain (TnIreg) showed a large mobility change by Ca2+ ion suggesting a Ca-induced switch movement of TnIreg. Spin dipole-dipole interaction showed that in reconstituted muscle fibers both skeletal and cardiac TnC undergo Ca2+-induced structural change that is thought to be essential for TnIreg movement. We also succeeded in fixing the newly-synthesized bifunctional spin label rigidly on the TnC molecule in solution, indicating that we can determine the precise coordinate of the spin principal axis of troponin on the oriented filament.     

Hot pressing of SiC-TiC composites

Sintering behaviour during hot pressing of SiC-TiC composite ceramics has been investigated with special emphasis on the effect of various processing parameters on the density and mechanical properties of the sintered body. At hot pressing temperatures greater than 2000° C, significant densification occurred in SiC-50 wt%TiC (–0.5 wt%B-1 wt%C) composites. The room temperature flexural strength of the sintered body increased with the hot pressing temperature up to 2000° C and reached a highest value of 710 MPa in accordance to the variation of density with temperature. In sintering of composites without additives, densification was enhanced with the addition of up to 25 wt%TiC, with relative densities higher than 98% observed when hot pressing at 2150° C for 2h.