Effect of Argon-Based Atmospheric Pressure Plasma Treatment on Hard Tissue Formation on Titanium Surface

In this paper, we suggest that the atmospheric pressure plasma treatment of pure titanium metal may be useful for improving the ability of rat bone marrow cells (RBMCs) to induce hard tissue differentiation. Previous studies have reported that the use of argon gas induces a higher degree of hard tissue formation. Therefore, this study compares the effects of plasma treatment with argon gas on the initial adhesion ability and hard tissue differentiation-inducing ability of RBMCs. A commercially available titanium metal plate was used as the experimental material. A plate polished using water-resistant abrasive paper #1500 was used as the control, and a plate irradiated with argon mixed with atmospheric pressure plasma was used as the experimental plate. No structural change was observed on the surface of the titanium metal plate in the scanning electron microscopy results, and no change in the surface roughness was observed via scanning probe microscopy. X-ray photoelectron spectroscopy showed a decrease in the carbon peak and the formation of hydroxide in the experimental group. In the distilled water drop test, a significant decrease in the contact angle was observed for the experimental group, and the results indicated superhydrophilicity. Furthermore, the bovine serum albumin adsorption, initial adhesion of RBMCs, alkaline phosphatase activity, calcium deposition, and genetic marker expression of rat bone marrow cells were higher in the experimental group than those in the control group at all time points. Rat distal femur model are used as in vivo model. Additionally, microcomputed tomography analysis showed significantly higher results for the experimental group, indicating a large amount of the formed hard tissue. Histopathological evaluation also confirmed the presence of a prominent newly formed bone seen in the images of the experimental group. These results indicate that the atmospheric pressure plasma treatment with argon gas imparts superhydrophilicity, without changing the properties of the pure titanium plate surface. It was also clarified that it affects the initial adhesion of bone marrow cells and the induction of hard tissue differentiation.     

Six-helix and eight-helix DNA nanotubes assembled from half-tubes

DNA nanotubes are cylinder-like structures formed from DNA double-helical molecules whose helix axes are fused at least twice by crossovers. It is potentially useful to use such tubes as sheaths around rodlike species that arise in biological systems and in nanotechnology. It seems easiest to obtain such sheathing by joining two or more components around an object rather than attempting to thread the object through a cavity in the tube. We report two examples of tubes containing a specific number of helices that are assembled from half-tube components. These tubes are a six-helix bundle and an eight-helix bundle, constructed respectively from two bent triple-crossover (BTX) molecules and from two four-helix arched motifs. Both species contain single strands in one molecule that are missing in its mate. The six-helix bundle is formed from two different BTX molecules, whereas the eight-helix species is a closed cyclic dimer of the same molecule. We demonstrate the formation of these species by gel electrophoresis, and we examine their arrangement into long one-dimensional arrays by means of atomic force microscopy.     

Capacitive sensing of electrocardiographic potential through cloth from the dorsal surface of the body in a supine position: a preliminary study

A method for obtaining electrocardiographic potential through thin cloth inserted between the measuring electrodes and the skin of a subject's dorsal surface when lying supine has been proposed. The method is based on capacitive coupling involving the electrode, the cloth, and the skin. Examination of a pilot device which employed the method revealed the following: (1) In spite of the gain attenuation in the high frequency region, the proposed method was considered useful for monitoring electrogardiogram (ECG) for nondiagnostic purpose. (2) The method was able to yield a stable ECG from a subject at rest for at least 7 h, and there was no significant adverse effect of long-term measurement on the quality of the signal obtained. (3) Electrode area was the factor that had most influence on the signal, compared with other factors such as cloth thickness and coupling pressure, but could be reduced to 10 cm2 for heart rate detection. (4) Input capacitance of the device was assumed to be the dominant factor for the gain attenuation in the high frequency region, and should be reduced with a view to diagnostic use. Although there is still room for improvement in terms of practical use, the proposed method appears promising for application to bedding as a noninvasive and awareness-free method for ECG monitoring.     

Heat transfer in high‐aspect‐ratio rectangular passage with skewed ribs

The heat transfer characteristics and flow behavior in a rectangular passage with two opposite 45° skewed ribs for turbine rotor blade have been investigated for Reynolds numbers from 7800 to 19,000. In this blade, the spanwise coolant passage at the trailing edge region whose thickness is very thin is chosen, so the channel aspect ratio (=width/height of channel) is extremely high, 4.76. Therefore the heat transfer experiment in the high‐aspect‐ratio cooling channel was performed using thermochromic liquid crystal and thermocouples. Furthermore, the calculation of flow and heat transfer was carried out using CFD analysis code to understand the heat transfer experimental results. The enhanced heat transfer coefficients on the smooth side wall at the rib's leading end were the same level as those on the rib‐roughened walls. © 2002 Scripta Technica, Heat Trans Asian Res, 31(2): 89–104, 2002; DOI 10.1002/htj.10018     

Preparation and characterization of carbonaceous materials containing nitrogen as electrochemical capacitor

Carbonaceous materials containing nitrogen (C/N materials) were prepared by a pyrolysis of 2,3,6,7-tetracyano-1,4,5,8-tetraazanaphthalene (CAN). A C/N material prepared by the pyrolysis of CAN at 1070 K (CAN-1070 K) had a C/N atomic ratio of 3.0 and a non-crystalline carbonaceous structure with a BET surface area of 880 m² g⁻¹. The material CAN-1070 K showed large capacitances of 160–180 F g⁻¹ and 110–120 F cm⁻³ in case of current density of 10 mA cm⁻² (2 A g⁻¹) by using three-electrode cell in 1 M H₂SO₄ aqueous solution, in comparison with that of activated carbon (160 F g⁻¹ and 55 F cm⁻³) having BET surface area of 2300 m² g⁻¹. ESCA study indicated that pyridinic and quarternary nitrogen atoms existed in the C/N materials, which could result in producing a pseudo-capacitance in addition to the electric double layer capacitance. Also introduction of nitrogen into the carbonaceous material could enhance the wettability of material, which might also improve the capacitance.     

A mathematical model of pacemaker activity recorded from mouse small intestine

The pacemaker activity of interstitial cells of Cajal (ICCs) has been known to initiate the propagation of slow waves along the whole gastrointestinal tract through spontaneous and repetitive generation of action potentials. We studied the mechanism of the pacemaker activity of ICCs in the mouse small intestine and tested it using a mathematical model. The model includes ion channels, exchanger, pumps and intracellular machinery for Ca2+ regulation. The model also incorporates inositol 1,4,5-triphosphate (IP3) production and IP3-mediated Ca2+ release activities. Most of the parameters were obtained from the literature and were modified to fit the experimental results of ICCs from mouse small intestine. We were then able to compose a mathematical model that simulates the pacemaker activity of ICCs. The model generates pacemaker potentials regularly and repetitively as long as the simulation continues. The frequency was set at 20 min(-1) and the duration at 50% repolarization was 639 ms. The resting and overshoot potentials were -78 and +1.2 mV, respectively. The reconstructed pacemaker potentials closely matched those obtained from animal experiments. The model supports the idea that cyclic changes in [Ca2+]i and [IP3] play key roles in the generation of ICC pacemaker activity in the mouse small intestine.     

Crystal structure of GdNi3 with superlattice alloy and its hydrogen absorption–desorption property

We synthesized the intermetallic compound GdNi₃, which has a PuNi₃-type structure (space group R-3m), and investigated its P–C isotherm. The refined lattice parameters were a = 0.4993(1) nm and c = 2.4536(4) nm. In the first absorption process, two plateaus were observed, and the maximum hydrogen capacity reached 1.07 H/M. In the first desorption process, a narrow and sloping plateau was observed at approximately 0.02 MPa. After the first full desorption, 0.6 H/M of hydrogen remained in the sample. This sample showed severe peak broadening in the XRD pattern, indicating that the metal sublattice deformed from the original alloy. No plateau region was observed in the second absorption–desorption cycle.