Ultrasonic cavitation in microspace

Ultrasound was irradiated to a micro-1D and -2D space having a characteristic length of 200 microm, and the presence of cavitation was confirmed from video images, and the generation of OH radicals, which was quantitatively evaluated with fluorometry.     

Optimum bubble temperature for the sonochemical production of oxidants

Numerical simulations of bubble oscillations in liquid water irradiated by an ultrasonic wave are performed for various acoustic amplitudes and various ambient pressures. In the numerical simulations, effect of non-equilibrium evaporation and condensation of water vapor at the bubble wall and that of chemical reactions of gases and vapor inside a bubble are taken into account. The oxidants such as OH radicals, O radicals, H(2)O(2) molecules, and O(3) molecules are created from water vapor inside a heated bubble when a bubble collapses strongly. They are dispersed into the liquid and solutes are oxidized by the oxidants, which is called sonochemical reactions. The computer simulations have revealed that there exists the optimum bubble temperature, which is about 5500 K, for the production of the oxidants inside an air bubble because at higher bubble temperature the oxidants are strongly consumed inside a bubble by oxidizing nitrogen. Correspondingly, there exists an optimum acoustic amplitude for the production of the oxidants, which is about 2.2 atm when the ultrasonic frequency is 140 kHz and the ambient pressure is 1 atm. For an oxygen bubble, on the other hand, the amount of the oxidants created inside a bubble becomes nearly independent of the bubble temperature at the collapse above about 6000 K because nitrogen is absent.     

New Infinite Series of Einstein Metrics on Sphere Bundles from AdS Black Holes

A new infinite series of Einstein metrics is constructed explicitly on S²×S³, and the non-trivial S³-bundle over S², containing infinite numbers of inhomogeneous ones. They appear as a certain limit of 5-dimensional AdS Kerr black holes. In the special case, the metrics reduce to the homogeneous Einstein metrics studied by Wang and Ziller. We also construct an inhomogeneous Einstein metric on the non-trivial S^d–2-bundle over S² from a d-dimensional AdS Kerr black hole. Our construction is a higher dimensional version of the method of Page, which gave an inhomogeneous Einstein metric on      

Whole-body transmission scintigraphy using a line source

Transmission scanning was proposed to be a useful adjunct to conventional emission scanning for accurately keying radionuclide deposition to radiographic anatomy. After introduction of a scintillation camera, transmission whole-body scintigraphy using a flood source has been performed in a patient with differentiated thyroid carcinoma. Recently immunoscintigraphy with radiolabeled monoclonal anti-tumor antibodies has become popular and transmission whole-body scintigraphy has been re-evaluated to make diagnosis for laterality of metastases. However, there are several problems to handle a flood source for preparation and shielding. We developed a special line source for transmission whole-body scintigraphy. The line source is composed of a plastic tube (inner diameter: 3 mm) with three-way stop in a U-shaped metal. There are several advantages to use this line source as compared to a flood one; (1) a small volume of radioactive solution (less than 5 ml), (2) easy preparation and setting, and (3) less radiation. Moreover good quality of transmission image is obtained using this line source.     

Collagen-protein interactions mapped by phototriggered thiol introduction

Accumulating evidence shows that collagen plays important roles in many biological systems by interacting with various proteins. The major limitation to determining protein-binding sites on collagen has been a lack of useful methods. We have developed a new strategy for mapping these sites using a photoreactive cross-linker, APDP. A unique -SH group can be introduced into collagen in the vicinity of the protein-binding sites by DTT reduction of the SS bond in the cross-linked product. To identify the sites of cross-linking in collagen, the strategy used was as follows: (i) derivatization of the free -SH group with fluorescein-5-maleimide (FM); (ii) fragmentation of collagen with an appropriate collagenase; (iii) separation of FM-labeled fragments by two-dimensional diagonal electrophoresis; and (iv) detection of cross-linked partners of collagen-binding protein as fluorescent spots under UV light. This strategy can be used to determine the binding sites of various proteins on collagen.     

Intermittent frequency offset lock of a symmetric three-mode stabilized He-Ne laser to an iodine stabilized He-Ne laser

There is a need for an intense, unmodulated single-frequency stabilized laser light that guarantees absolute optical frequency in a rapid laser calibration or an ultra-high resolution interferometer. To obtain such a light, we developed a new laser system that uses an intermittent frequency offset lock of a symmetric three-mode stabilized He-Ne laser to an iodine stabilized He-Ne laser. The proposed laser system provides two operational modes: (1) independent and (2) slave mode. In the independent mode, frequency of the three-mode laser is stabilized via control of frequency difference between two intermode beats. The resultant output is a single longitudinal mode light of maximum intensity that locates at the top of the gain curve. Frequency instability of 8X10^-12 (at a sampling time of 100 s) which is better than conventional stabilized lasers is attained in the independent mode. Slow optical frequency drift during the independent mode is periodically corrected by the offset lock to the iodine stabilized laser (slave mode), resulting in accurate reset of the frequency drift. After reset of the frequency deviation, the three-mode laser is again operated in the independent mode. Due to such intermittent offset lock, duty factor of the iodine stabilized laser was reduced to a few % of continuous operation.