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Methanobrevibacter oralis is an archaeal species frequently isolated from sites of severe periodontitis. However, its pathogenic roles remain unclear. Here, we aimed to isolate group II chaperonin from M.?oralisand examine its antigenicity. The genes encoding two chaperonin subunits (Cpn-1 and Cpn-2) were cloned from M.?oralisusing polymerase chain reaction and genome walking procedures. Recombinant proteins Cpn-1 and Cpn-2 were generated, and the reactivities of sera from patients with periodontitis were examined by Western immunoblotting. The open reading frames of Cpn-1 and Cpn-2 genes consisted of 1641 and 1614 base pairs, respectively. Putative ATP-binding domains conserved among the chaperonin family were observed in both genes. The deduced amino acid sequences of the two genes showed 28.8-40.0 identity to each of the subunits of human CCT (CCT1-8). Thirty and 29 of 36 patients' sera reacted with the recombinant Cpn-1 and recombinant Cpn-2, respectively. Western immunoblotting using antiserum against human CCT subunits indicated that anti-CCT3 and anti-CCT8 antibodies recognized recombinant Cpn-1. In addition, anti-CCT1, CCT3, CCT6, and CCT8 antibodies recognized an antigen of approximately 60?kDa in M.?oralis. The results suggested that the chaperonin subunits of M.?oraliswere antigenic molecules that were recognized by periodontitis patients and that may cross-react with human chaperonin CCT.

AbstractSince carbon deposition layers in tokamak devices will contain significant amount of tritium, it is important to study its formation mechanism. In this study, tungsten and molybdenum samples with a temperature gradient were irradiated by a mixed ion beam to precisely study temperature dependence of the deposition characteristics. For molybdenum, the temperature of the boundary between “deposition” and “nodeposition” is higher than W. This results roughly agree with the results by the material mixing model proposed by Kriegeretal [K. Krieger. J. Roth. J. of Nucl. Mater. 290-293 (2003) 107.]. Erosion yield of C deposition layer in our experimental conditions was almost equal or less than the yield by Rothmodel [J. Roth, C. Garcia-Rosales, Nucl. Fusion 36 (1996) 1647] for graphite.

Spot heating system utilizing a fiber-laser has been developed in order to control recrystallization, grain growth process and texture development. The newly developed system enables the laser beam to be focused onto the surface of specimen with a minimum diameter of around 10 m. The maximum power of laser in the present system is 100W. Specimens of cold rolled pure aluminum plates of 1mm thick are used for local recrystallization treatment by the spot heating. After laser-spot heating, preferentially recrystallized grains appeared in the irradiated and heat affected region with a diameter depending on the laser power density. The present system enables spot heating on any critical points of the specimen surface. Some laser-heated specimen show locally recrystallized regions occupied by almost single grain having similar crystallographic orientation as that of cold rolled matrix. But the orientation of recrystallized grain is not always the same as that of the matrix. Selective spot heating on grains having peculiar orientation would bring about a possibility of texture control that has not been achieved by means of conventional materials processing.

The present study tried to control grain structure in polycrystalline aluminum or titanium by means of a laser spot heating method as well as by a computer simulation technique. Monte Carlo simulation of spot heating was performed utilizing two-dimensional grain structure model composed of 200 x 200 sites with hexagonal cells. Grain growth proceeded preferentially in the higher temperature region and resulted in a large grain surrounded by small grains. This large grain tended to keep on growing during homogeneous heating after the spot heating, suggesting that the spot heating technique can fabricate a peculiar grain structure such as different grain size distribution and texture that are not realized by utilizing conventional uniform heating process. Laser spot heating utilizing a fiber-laser system realized heating of small area such as 30micorn diameter to bring about peculiar grain size distribution as calculated by the computer simulation.

The characteristic of the electrostatic mode excited in non-neutral plasma in the equilibrium state is closely related to the internal state of plasma. This relationship has been used for non-destructive diagnosis of non-neutral plasma. Under the present conditions, this diagnosis is only supported by simplified theory. We employ numerical simulation reflecting actual experimental conditions and examine the characteristic of this electrostatic mode.

We review our recent studies on structure formation in pure electron plasmas confined in magneto-electric traps. Two-dimensional dynamics of strongly magnetized plasmas is studied in terms of a two-dimensional vortex composed of high-density clumps and a low-density distribution in the background (BG). By controlling the initial distributions we examine in detail the fundamental processes where the clumps form highly ordered geometrical configurations (vortex crystals). Experimental studies of the formation of three-dimensional density structures have been initiated with a newly built strong-magnetic-field (2.2?T) trap operatable with various potential profiles including a square-well potential (Malmberg trap) and harmonic potential (Mohri trap). In the Mohri trap, Penning-type distributions are observed to form as a result of interaction of string-shaped distributions of electrons. The density distributions observed in the relaxation process are quite different from those observed in a square-well potential most probably due to three-dimensional deformations and merger of the string distributions. The equilibrium distributions generally consist of sets of spheroidal distributions, a core distribution plus halo distributions. Observationally the halo distributions appear to be associated with the amount of excessive angular momentum provided through the injection of off-axial electron strings. Like the BG vorticity distribution in the two-dimensional merger of clumps, the halo may act as the absorber of momentum in the course of the merging process of strings to create the core distribution. In the Penning-like distributions we have also observed the accumulation of negative ions replacing the electrons in time scales much longer than thermal relaxation.

The purpose of this study was to evaluate the role of the endothelial cell reaction after endovascular coil embolization for the treatment of intracranial aneurysms. A scanning electron microscopic (SEM) study of the platinum coil, embolized into a middle cerebral aneurysm in a 35-year-old woman and subsequently removed surgically eight months later, revealed no endothelial coverage on the coil.This finding prompted us to perform experimental studies. In the first in vitro study, endothelial cells from gerbil brain microvessels and canine carotid arteries were co-cultured with either bare-form platinum coils or type-1 collagen-coated coils for up to three weeks, and the endothelial cell population on the coils was ascertained. In the second in vivo study, platinum coils coated with type-1 collagen were delivered endovascularly into canine carotid arteries, while the contralateral side was treated with bare-form coils, and endothelialization over the coil was investigated.SEM studies revealed that no endothelial cells, either from gerbil brain microvessels or from canine carotid artery, were found on the uncoated coils, whereas gerbil endothelial cells began to proliferate on the collagen-coated coils in three days, covering extensively in one week and reaching confluence in two weeks in vitro. The in vivo canine study demonstrated that bare-form platinum coils did not show endothelial coverage until two weeks, but endothelial cells proliferated directly on the collagen-coated coils in three days, and coils were completely covered in two weeks.These results supported the SEM study of our case and several human histopathological reports in the literature in that endothelial cell coverage in the orifice of the intracranial aneurysm is exceptional after endovascular treatment. But if some extracellular matrix, like collagen in our study, is prepared, coverage could be possible, as is seen in a few human cases. Biological modification of the platinum coils, such as collagen coating, is awaited for the better long-term results of endovascular coil embolization without recanalization of the treated intracranial aneurysms.

The effect of palladium (Pd) addition to Ti-Ni alloy as the third element was investigated to improve the super-elasticity of the alloy castings at body temperature for dental application. Ti-50.8Ni (at %) alloy, which exhibited super-elasticity at 310 K in castings, was used for comparison. 5.0, 7.5, 10.0 and 15.0 at % Pd was added to Ti-50.0Ni alloy by the substitution for Ni. The change in the proportion of Ti and Ni was also examined at the fixed Pd addition of 7.5 at %. The properties of the alloys were investigated in tensile test and differential scanning calorimetry (DSC). Ti-42.5Ni-7.5Pd alloy castings showed good super-elasticity among the examined alloys from the viewpoint of residual strain and elongation. Moreover, apparent proof stress could be changeable by the proportion of Ti and Ni with residual strain being kept low. Ti-42.5Ni-7.5Pd alloy castings exhibited better super-elastic flexibility than Ti-50.8Ni alloy, which is proven by lower apparent proof stress and larger elongation. This flexibility appears to be caused by its relatively high martensitic transformation starting temperature point. It is suggested that this flexibility with super-elasticity could widen the clinical application of the alloy casting in dentistry. © 2000 Kluwer Academic Publishers

Films of ultrahigh molecular weight (5.4×106) polypropylene were produced by gelation/crystallization at various temperatures from dilute decalin solutions according to the method of Smith and Lemstra. The temperatures chosen were 20°, 30°, 50°, and 60°C. With increasing the temperature, the long period and crystallinity of the resultant gel film increased. By contrast, when the films were stretched up to 50 } 60 times, the increases in Young's modulus and crystallinity become more significant, as the temperature of the gelation/crystallization became lower. This interesting phenomenon is thought to be due to the dependence of the number of entanglements on the temperatures concerning gelation/crystallization and evaporation of solvent from the gel to form a film.