Use of plastic bar molded casting in the modification of variably expanding investment to compensate for casting shrinkage of nickel-chromium alloy

Trial plastic bar molded castings were compared for accuracy with cast crowns by means of a nickel-chromium alloy, which was used to establish the liquid density of variably expanding investments. The plastic bars were invested to evaluate the change of expansion rate in a wide range of six liquid densities from 0% to 100%, and the distances between the sections were measured before and after casting. Wax crowns were cast to obtain a more detailed relation around 0% expansion at seven liquid densities, and the gaps between the base of the die and the margin of the crown were measured before and after casting. The expansion rates of both castings were calculated and thus were proportional to the liquid density; both regression curves indicated high correlation coefficients. As a result of the statistics of the Student's t-test, the difference between the two methods was not significant. The trial plastic bar was useful in establishing the variably expanding investment for precise casting of artificial crowns.     

Education and research in Japan

Good education has given Japanese industry and research an advantage over many other countries. Using personal experience of education and research in Japan, the authors outline the present education process and some future developments. The pervasiveness and homogeneity of the main-stream education system in Japan is first described. The programme of study and spartan life of students in university faculties are then outlined. The types of research open to successful students in Japan are illustrated by a broad outline of its funding and examples of research programmes     

A translocation t(8;14) and c-myc gene rearrangement associated with the histological transformation of B-cell acute lymphocytic leukemia (FAB-L2) into Burkitt''s type (FAB-L3) leukemia

During the late rainy season and winter season in 1990, outbreaks of suspected trypanosomiasis in native cattle (Bos indicus) occurred on 13 farms in Petchaboon province, Thailand. Forty-two cattle presented with nervous symptoms including circling, excitation, jumping, aggressive behavior, lateral recumbency, convulsion and finally death. Blood samples from 39 cattle on the two farms in which the outbreaks occurred were collected and examined for the presence of Trypanosoma evansi. It was found that all 16 blood samples from cattle on farm A were positive of T. evansi by mouse inoculation and indirect fluorescent antibody test (IFAT). In cattle from farm B, on the other hand only 37.5% and 39% of the samples were positive by mouse inoculation and IFAT, respectively. T. evansi was detected on impression smears of organs from the three cattle which died with nervous symptoms and also in smears made from their cerebrospinal fluid. In addition, trypanosomes were isolated from the cerebrum, cerebellum, pons and spinal cord by mouse inoculation.     

Investigation of Tribo-chemistry by means of Stable Isotopic Tracers: TOF-SIMS Analysis of Langmuir–Blodgett Films and Examination of their Tribological Properties

Deuterium-substituted and ¹³C-substituted octadecanoic acids were applied to study tribo-chemistry of binary-component Langmuir–Blodgett film deposited on Si(100) surfaces. Time-of-flight secondary ion mass spectroscopy was employed to study structure of the film. The isotopic tracers give typical fragment ions composed of the isotopes. Among these typical fragment ions, we paid attention to quasi-molecular ions and deuterium ion as “fingerprint region” of the film structure. The tribological properties of the binary-component film were evaluated by ball-on-plate type tribo-testers. The combination of octadecanol with octadecanoic acid affords good tribological properties, whereas the combination of octadecylamine with the acid gave poor results. The surface analysis of the plate after the tribo-test revealed that the alcohol and the acid were retained on the track even after the rubbing. On the other hand simultaneous removal of the acid and the amine from the surfaces were observed. Interactions between the acid and the amine were considered by the results of the tribo-tests and the surface analysis of the binary-component film.     

X-ray computed tomography used to measure fiber orientation in CFRP laminates

This paper explains a new method to measure the fiber orientation in carbon fiber reinforced plastics (CFRP) laminates from X-ray CT images. In the method, the fiber orientation is analyzed by the application of digital image correlation (DIC) method to the acquired tomographic images. Using DIC, the brightness pattern, which results from the radiodensity difference between fiber and resin, is compared between two different planes in the thickness direction. Then, the three-dimensional displacement of the brightness pattern, which indicates the fiber orientation, can be measured. This study applied the proposed method to a quasi-isotropic CFRP laminate. After X-ray CT imaging, the sample was sectioned and polished. The fiber orientation was then measured experimentally using microscopy. The fiber orientation calculated using the proposed method agrees very well with the experimentally measured one. After demonstrating the validity of the proposed method, we applied it to a plain woven CFRP laminate. Results revealed that an invalid fiber orientation might be calculated for fibers parallel to the plane of the CT image, or for the fiber orientation of the pattern around the outer edge of CT images.     

Ultrasonic motors using piezoelectric ceramic multimode vibrators

The development is reported of an ultrasonic motor using piezoelectric ceramic multimode vibrators consisting of circular or annular plates in which degenerate horizontal vibration modes of the same or different form are used. Two orthogonal nonaxisymmetric vibration modes were used in the same-form case, and the combination of a nonaxisymmetric vibration mode and a radial vibration mode was used in the different-forms case. Some details of the motor design and its experimental characteristics are presented. The ultrasonic motor presented here has a special advantage in its thin construction.     

DCOB: Action space for reinforcement learning of high DoF robots

Reinforcement learning (RL) for robot control is an important technology for future robots since it enables us to design a robot’s behavior using the reward function. However, RL for high degree-of-freedom robot control is still an open issue. This paper proposes a discrete action space DCOB which is generated from the basis functions (BFs) given to approximate a value function. The remarkable feature is that, by reducing the number of BFs to enable the robot to learn quickly the value function, the size of DCOB is also reduced, which improves the learning speed. In addition, a method WF-DCOB is proposed to enhance the performance, where wire-fitting is utilized to search for continuous actions around each discrete action of DCOB. We apply the proposed methods to motion learning tasks of a simulated humanoid robot and a real spider robot. The experimental results demonstrate outstanding performance.     

Real‐time up‐converter from HDTV to 4K with super‐resolution: Breaking the Nyquist frequency barrier

This real‐time up‐converter from high‐definition television (HDTV) to 4K with a novel super‐resolution (SR) creates 4K video with frequency elements higher than the Nyquist frequency of the original HDTV video. The novel SR uses non‐linear signal processing to overcome the theoretical limitation of the Nyquist frequency.     

Water-filled single-wall carbon nanotubes as molecular nanovalves

It is known that at low temperature, water inside single-wall carbon nanotubes (water-SWNTs) undergoes a structural transition to form tube-like solid structures. The resulting ice NTs are hollow cylinders with diameters comparable to those of typical gas molecules. Hence, the gas-adsorption properties of ice- and water-SWNTs are of interest. Here, we carry out the first systematic investigation into the stability of water-SWNTs in various gas atmospheres below 0.1 MPa by means of electrical resistance, X-ray diffraction, NMR measurements and molecular dynamics calculations. It is found that the resistivity of water-SWNTs exhibits a significant increase in gas atmospheres below a critical temperature Tc, at which a particular type of atmospheric gas molecule enters the SWNTs in an on-off fashion. On the basis of this phenomenon, it is proposed that water-SWNTs can be used to fabricate a new type of molecular nanovalve.     

The use of heterologous promoters for adeno-associated virus (AAV) protein expression in AAV vector production

OBJECTIVE: There are few nonproprietary papers addressing the mechanical strength of intramedullary nails; none address the characteristics of the proximal and distal ends of these devices. Our objective was to provide such data. DESIGN: Independent testing of eight femoral intramedullary nail systems at the proximal, middle, and distal regions was undertaken to evaluate strength and flexural rigidity (stiffness). METHODS: Each device, usually a reconstruction nail, was forty-two to forty-six centimeters in length. Four or five nails of each available size (range 9 to 13 millimeters in diameter) were tested for each system. The nails were cut into proximal, middle, and distal thirds. Each nail section was loaded to failure using a four-point bend test on a custom fixture (modification of the American Society of Testing Materials standard test). RESULTS: Significant variations (p < 0.05) were found in strength and stiffness between the middle and the proximal or distal aspects of some rods. A significant difference (p < 0.05) was observed when comparing the properties of earlier designs with the properties of more recent designs. Newer rod designs all performed in a similar manner with regard to strength. Strength and rigidity increased with increasing rod diameter in some but not all systems. CONCLUSIONS: Although none of the newer designs appeared to have superior static strength, the individual systems had significant variations in their mechanical properties (bending rigidity), particularly in the proximal and distal sections. It is important that the surgeon become familiar with the individual characteristics of strength and rigidity for the particular devices available and how these might impact fracture healing. Consideration of this information could alter the decision to select one system over another in a complex fracture situation.