Cytosine detection by a fluorescein-labeled probe containing base-discriminating fluorescent nucleobase

We report on a new method for the detection of a base at a specific site in a DNA sequence by monitoring the fluorescence emission of fluorescein. To achieve this goal, we developed a new base-discriminating fluorescent (BDF) nucleobase, naphthodeazaadenine ((ND)A). The fluorescence spectrum of the duplex possessing a cytosine base as a complementary base of (ND)A showed a fluorescence peak at 383 nm when using an excitation wavelength of 350 nm. When the complementary base of (ND)A was one of the other bases, the fluorescence intensity was very low. The fluorescence emission spectrum of (ND)A overlapped with the fluorescence excitation spectrum of fluorescein in the wavelength range of 400-500 nm. Thus, we designed FRET-BDF probes containing (ND)A as the FRET donor and fluorescein as the acceptor. The interaction of these two fluorophores, which are separated by defined base pairs, allowed an efficient energy transfer that resulted in a dominant fluorescence emission of fluorescein at 520 nm when using an excitation wavelength of 350 nm. Fluorescence emission from FRET-BDF probes was observed only when the complementary base of (ND)A is C, thus achieving a clear distinction of a C base on the complementary DNA strand. However, the general utility of our method is limited due to the quenching of the (ND)A fluorescence by a G/C base pair flanking (ND)A.     

Electrochemical reduction of acetone on mercury electrode in aqueous sulphuric acid solution

Electrochemical reduction of acetone in aqueous H₂SO₄ solution was studied on Hg electrode by galvanostatic, potentiodynamic and polarographic methods. Electrocapillary curves show that acetone molecule adsorbs to a monolayer at concentrations larger than 0·5 M in a potential range of 0 > V > ? 1·0 V (nhe). It orients with the positive end of the dipole toward electrode surface and extends an attractive interaction to its neighbours.Kinetics oberved by galvanostatic pulse method and polarography leads the following conclusions; (1) adsorbed acetone molecule undergoes elecrochemical reduction at potentials more negative than ?1·0 V (nhe), (2) reaction rate is the first and second order with respect to the amount of adsorbed acetone and proton activity, and (3) one electron transfer step determines the reaction rate (Tafel slope is 0·12 V). Reaction intermediate is concluded from the potentiodynamic study to be isopropanol radical, (CH₃)₂??OH, whose amount is proportional to that of adsorbed acetone and to a_H+. From the above results, the rate of the electrochemical reduction of acetone is H₂SO₄ solution is concluded as determined by the step, (CH₃)₂?OH(a) + H⁺ + e^? → (CH₃)₂CHOH.     

Synthesis and Properties of Cross-Linked Poly(vinylene-arsine)

Summary Cross-linked poly(vinylene-arsine)s (4) were synthesized by a free-radical terpolymerization of phenylacetylene (2), hexaphenylcyclohexaarsine (l), and p- or m-diethynylbenzene (p- or m-3) at different compositions in the presence of a catalytic amount of AIBN. The number-average molecular weights of the resulting polymers were a few thousands estimated by gel permeation chromatography (GPC) analysis. By gas chromatography (GC) analysis p-3 was found to be more reactive during the polymerization than m-3 and the resulting cross-linked polymer (p-4) showed lower solubility than that of m-4. The cross-linked poly(vinylene-arsine)s showed higher glass transition temperature in the measurement of differential scanning calorimetry (DSC) and more red-shifted emission in chloroform solution than that of the linear poly(vinylene-arsine). These properties could be tuned by varying the monomer feed ratio.     

Effects of calcium stearate addition of ultrahigh molecular weight polyethylene in direct compression molding

The effects of calcium stearate addition in molding of ultrahigh molecular weight polyethylene (UHMWPE) were investigated by tensile testing, scanning electron microscope (SEM), Fourier transform infrared (FT‐IR) spectroscopy, and elemental analysis. Four types of UHMWPE specimens with varying contents of calcium stearate (<5, 50, 100, and 1000 ppm) were used in this study. SEM observation revealed that calcium stearate added specimens have smoother and more homogeneous microstructures. After accelerated aging, subsurface oxidative degeneration was observed in all specimens; however, calcium stearate added specimens had less oxidative degeneration in comparison with specimens without additives. Specimens showed better mechanical properties with increasing content of calcium stearate. Though all specimens aggravated their mechanical properties due to oxidation after accelerated aging, the specimens of 100 ppm of calcium stearate showed better properties at 3.7 MPa larger yield strength and four times larger value of elongation at fracture than the specimens without additives. These results indicate that calcium stearate addition produces dense packing of UHMWPE particles, which brings about stronger fusion among the particles and fewer structural defects, and results in better mechanical properties and better resistance to oxidative degeneration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1602–1609, 2003     

Grapefruit juice enhance the uptake of coenzyme Q10 in the human intestinal cell-line Caco-2

Coenzyme Q10 (CoQ10) is very widely consumed by humans as a food supplement. However, CoQ10 is taken up from the intestine into the circulation at a low rate. The absorption of compounds from the gastrointestinal tract is one of the important determinants for oral bioavailability. Secretory transport limits the oral bioavailability of compounds. It has been reported that efflux transport of CoQ10 is mediated by P-glycoprotein (P-gp) in Caco-2 cells. We tried to improve intestinal absorption of CoQ10 by modulating P-gp. Since grapefruit juice (GFJ) is reported to inhibit P-gp function, we investigated the effect of GFJ on the transport of CoQ10 by Caco-2 cells. In the presence of GFJ, the basal-to-apical transport of CoQ10 was decreased and the uptake of CoQ10 was increased. These findings suggest that the combined administration of CoQ10 and GFJ could enhance CoQ10 absorption.     

Response of osteoblast-like MG63 cells to TiO2 layer prepared by micro-arc oxidation and electric polarization

Micro-arc oxidation (MAO) is one of the useful surface modifications of titanium implants to improve bioactivity. Also, electric polarization treatment enhances bioactivity of calcium phosphate. The aim of this study was to evaluate the effect of the combination of two surface modifications, micro-arc oxidation (MAO) with electric polarization, on the behavior of osteoblast-like osteosarcoma MG63 cells. MAO-treated materials had a surface geometry that was favored by MG63 cells as determined using scanning electron microscopy and X-ray diffraction; additionally, electric polarization induced surface electric fields, which were measured using thermally stimulated depolarization currents. The results of assays to study cell–material interactions suggest that these two approaches could regulate cell attachment, spreading, proliferation, and differentiation without the addition of other reagents. This new surface modification processes produce materials with a good surface geometry, generate surface electric fields and enhance the osteopromotive ability of osteoblasts.     

A Study about the Effect of Space Size on the Individual Distance

This study is the design guidelines for the living space with robots. The study can be applied to the architectural planning and focused on the basic environmental primary factor. The authors focused on space size, specifical distance from the wall in the front direction, position, and distance between an individual as factors affecting individual distance. The authors research the distances a small mobile robot moves to a six mats space compared with that toward a distances 5 m or more （space less physical factors）. The following three results were obtained： （1） The individual distance is smaller than 30 cm in both the approach angle in the experiment space of six mats; （2） The distance from the wall in the front increased, and the individual distance between a participant and a robot also increased; （3） In terms of body position, the upright positioning was clarified and the individual distance was small.