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Objective Focal accumulations in the skeleton were analyzed in order evaluate the usefulness of bone scintigraphy in the detection of distant skeletal metatases originating from malignant oral tumors.

Responses of structure and mineral content in weight-bearing bones to 1-week hindlimb suspension were studied in growing rats. The weight, volume, and length of femur, tibia, and fibula were less in suspended rats than cage controls, although there was no significant difference in the weight/volume ratio. The diameter of mid-shaft, the thickness of cortical bone, and the ratio of cortical bone thickness to femur diameter were significantly less in the suspended rats. The width of marrow space showed no differences, suggesting that the cortical bone was mainly affected. The sum of mineral content and the mineral content per diameter in the cross section of femurs were decreased following suspension, suggesting a change in the internal structure of cortical bone. Data also indicated that the reduction of femur diameter was caused by decreased thickness which is accompanied by the decreased mineral content of the cortical bone. It was suggested that there is a close relationship between the responses of bones and muscles to hindlimb suspension of young rats, although the degree of weight loss was greater in muscles than in bones.

Objective: The purpose of this study was to differentiate between malignant tumors and benign tumors of the head and neck by means of thallium-201 chloride scintigraphy. Study Design: Thallium-201 chloride (Tl-201) scintigraphy and Ga-67 citrate (Ga-67) scintigraphy were performed in 10 patients with a benign tumor and in 90 patients with a malignant tumor. The blood flow index and the tumor retention index were obtained by means of Tl-201 scintigraphy. The blood flow index = the count of tumor/the count of control in the early dynamic scan from 30 to 120 seconds after injection, and the tumor retention index = (the count of tumor/the count of control in the delayed dynamic scan 2.5 hours after injection)/(the count of tumor/the count of control in the early dynamic scan from 4 to 5 minutes after injection). Results: The early and delayed scans with Tl-201 demonstrated a very high correlation with the blood flow index. The tumor retention index had a tendency to increase in malignant tumors, especially in the poorly differentiated tumors and the severely invasive tumors. Likewise, the tumor retention index decreased in benign tumors. These results proved to be statistically significant, and in turn Tl-201 scintigraphy was deemed superior to Ga-67 scintigraphy. Tl-201 scintigraphy was also useful in detecting small-size tumors. Conclusion: The tumor retention index of Tl-201 was useful for the differentiation of malignant tumors of the head and neck from benign tumors of the same areas. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;92:228-35)

To study the structure of an edge dislocation core in an ionic crystal, we measured the amplitude dependence of internal friction by the automated Marx's composite oscillator method and the vibrational current caused by charged dislocations in a hydrogen-absorbed NaCl single crystal. The change of the sign of dislocation charge at the strain amplitude of 10-6 disappeared with absorption of hydrogen, while it was preserved using helium. These findings suggest that hydrogen exists as a positive ion in the dislocation core.

We measured internal friction, Young's modulus, ionic conductivity corresponding to the density of vacancies and the dielectric loss corresponding to the dipole density at the same time by an automated Marx's composite oscillator method, in order to investigate the internal friction peaks of NaCl single crystal around 90°C. We observed peaks for both internal friction and dielectric loss, and interpreted the peaks to reflect relaxation by dipole reorientation.

To study the behavior of dislocation core in AgCl, we measured the amplitude dependence of internal friction by automated Marx's composite oscillator method and the vibrational current caused by charged dislocations, which are driven with the frequency of external force, f R=50 kHz. We obtained the association energy between vacancy and metallic impurity as E A=0.96 eV and the binding energy between dislocation and vacancy as E b=0.66 eV combining ionic conductivity measurements.

Internal friction and Young's modulus were measured in a deuterium-absorbed titanium rod during the heating process from liquid nitrogen temperature, but no change was observed at 30 °C, the point at which neutrons were detected by a Los Alamos group. An internal friction peak was observed at -70 °C.

To study the structure of the core of an edge dislocation in ionic crystal, we measured the amplitude dependence of internal friction by automated Marx's composite oscillator method and the vibrational current caused by charged dislocations. The phase angle between vibrational current and strain suddenly changed by 180 degrees at a strain amplitude of 10-6. From this fact we discuss the structure of the dislocation core.

We developed Marx's composite oscillator method to an automatic control system to keep the strain amplitude constant at fundamental and third overtone frequency. Stability of this control system is analyzed by an automatic control theory in the measurement of internal friction with varying strain amplitude, temperature, and external field. It is applied to measurement of a relaxation peak at a fundamental frequency of 50 kHz and overtone 150 kHz of the same specimen to study the relaxation process of AgCl.

Marx's composite oscillator method has been successfully automated for measuring internal friction and Young's modulus. The apparatus automatically finds the mechanical resonant frequency of the composite oscillator and keeps the strain amplitude constant, so that internal friction and the modulus can easily be measured and directly recorded on an X-t recorder. This device enables us to observe continuously the time dependence of the pinning and unpinning processes of dislocation by point defects. The error in strain amplitude is suppressed to within ±0.1%, while the internal friction value changes by 2 orders of magnitude. The operation of this system has been analyzed by automatic control theory, and the theoretical results are in good agreement with the experiment results. The analysis and the application of this method are presented here together with some experimental results.

By automated Marx's composite oscillator method, changes of internal friction with the pressure of nitrogen, oxygen, and argon were measured. The range of the measurement was from a pressure of 103 mbar to 10-5 mbar. An application to a wide range vacuum gauge was discussed.

The ion beam excited acoustic microscope (IAM) is a new microscope which provides visual representations of the elastic waves caused by localized chopping ion energy. Topographs of ultrasonic attenuation and local elastic variations were obtained by measuring frequency and amplitude at a composite resonant point between transducer and sample. Specific ion images were also obtained from the same measurement. In this paper, the IAM and observed topographs and intensity modulated images of the specific ions are described. The elasticity of the hydroxyapatite crystal of the teeth is examined.