Although hydroxyapatite (HAP) and tricalcium phosphate (TCP) are currently used as bone graft substitutes or coatings on metallic prostheses because of their excellent biocompatibility and osteoconductivity, they do not stimulate bone formation or inhibit bone resorption. Zinc, an essential trace element in many animals, has a direct specific proliferative effect on osteoblastic cells and has a potent and selective inhibitory effect on osteoclastic bone resorption in vitro. Therefore, zinc-containing beta-tricalcium phosphate (ZnTCP) ceramics and composite ceramics of ZnTCP and HAP (ZnTCP/HAP) were implanted in the femora of New Zealand White rabbits for 4 weeks to promote bone formation. The implants were sintered ceramics with zinc contents of 0 (control), 0.063, 0.316 and 0.633 wt %. Histological and histomorphometrical investigation of the undecalcified sections revealed an increase by 51% (p =.0509) in the area of newly formed bone around the ZnTCP/HAP implants of 0. 316 Zn wt % compared with the control. Plasma zinc concentration was unchanged. An increased bone resorption on the endosteal surface was observed when ZnTCP and ZnTCP/HAP of 0.633 Zn wt % were implanted. To promote bone formation, the optimum zinc content of the calcium phosphate ceramics was therefore 0.316 wt %.
Zinc is an essential trace element with stimulatory effects on bone formation. Therefore, zinc was doped into beta-tricalcium phosphate to develop zinc-releasing biomaterials to promote bone formation. The zinc-doped beta-tricalcium phosphate, beta-tricalcium phosphate, and hydroxyapatite powders were mixed at a (Ca+Zn)/P molar ratio of 1.60, followed by sintering into a dense body at 1100 degrees C for 1 h. The sintered body was a composite ceramic consisting of zinc-doped beta-tricalcium phosphate and hydroxyapatite phases. The composite ceramic contained zinc oxide when the zinc content was higher than 1.20 wt %. The composite ceramic released zinc under pseudophysiological conditions. However, the release of calcium and phosphate decreased with an increase in zinc content in a range higher than 0.12 wt % owing to a decrease in solubility of the zinc-doped beta-tricalcium phosphate phase. Proliferation of osteoblastic MC3T3-E1 cells was significantly increased on the composite ceramic with a zinc content from 0.6 to 1.20 wt %, compared with those without zinc. When the zinc content was higher than 1.20 wt %, release of zinc from the zinc oxide caused cytotoxicity. Therefore, the zinc content of the composite ceramic must be <1.20 wt %.
A network that shows dynamical change in response to each input pattern works as a reservoir. In this study, we propose to use a network of Ag2S islands for reservoir computing. Input of a small number of electrons to an Ag2S island from a neighbored island causes Ag nanowire growth, which eventually connects the two islands. Shrinkage of an Ag nanowire also occurs depending on the distribution of a local electric potential. Thus, growth and shrinkage of Ag nanowires among Ag2S islands shows dynamical change in conductive channels responding to input bias, which is demonstrated by an Ag2S-island network surrounded by input/output electrodes. The Ag2S islands that are electrically connected to a surrounding electrode are identified using a conductive-atomic force microscope, confirming the operating mechanism.
The authors utilized a SAW directional coupler which consists of two IDTs and two waveguides with a horn structure for focusing SAW at each end of the waveguides, as an electrostatic voltage sensor and a displacement sensor. In the electrostatic voltage sensor, electrostatic voltage is applied on the surface of the substrate between two parallel waveguides.An amplifier was connected between the two IDTs, and a SAW oscillator with the oscillation frequency 10 MHz was constructed. The senitivity of the sensor is 0.07 Hz/V for the waveguide distance 0.4 nun.The displacement sensor consists of two substrates, on each one of which an IDT and a waveguide with a horn structure were formed by A1 deposition. The two substrates are contacted on the surfaces with the waveguide, with each other, and one is movable OK slides to the other. Thus a dirctional coupler with a variable coupling distance was performed, and a SAW oscillator was constructed by connecting an amplifier.The oscillation frequency is changed by moving or sliding one substrate and fixing the other. The sensitivity of the sensor is 50 kHz/mm.
ABSTRACT. A device has been developed that is useful for the size measurement of volatile liquid droplets. In this device, droplets are sampled into a tube, where they are allowed to collide with a hot-film sensor, which has originally been designed for use in a constant-temperature anemometer. Upon a collision of each droplet, a pulse is formed in the voltage applied to the sensor, and the diameter of the droplet is obtained directly from the pulse area; no calibration with any standard is necessary. The accuracy of the hot-film method was proved through test experiments in which water droplet sizes measured by the present device were compared with those measured by a microscopic photographic or a gravitational settling method. By evaluating the detection efficiency of droplets, the number concentration of droplets was also obtainable. The device was shown to be applicable to ethanol droplets as well as to water droplets. A field test to observe a fog event was carried out, and it was found that the variation of the liquid water content could be tracked with a measurement interval of about 3 min. AEROSOL
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