Cytocompatibility of calcium phosphate coatings deposited by an ArF pulsed laser

In the current studies, we deposited ultra-thin hydroxyapatite films on a pure titanium substrate by pulsed laser deposition, and we examined the effects of these surfaces on rat bone marrow (RBM) cells. This method allowed deposition of 500-, 2000-, and 5000-Angstrom-thick hydroxyapatite films. X-ray diffraction showed that the amorphous films recrystallized to a hydroxyapatite crystal structure after annealing. The proliferation of RBM cells was unaffected by the hydroxyapatite films, but osteocalsin and alkaline phosphatase mRNA and protein levels were elevated in cells grown on 2000- and 5000-Angstrom-thick films. These results indicate that ultra-thin hydroxyapatite films generated by pulsed laser deposition are better at promoting osteogenesis than pure titanium surfaces.     

Absolute phase measurements using geometric constraints between multiple cameras and projectors

The method of phase shift with the projection of multiple cyclic patterns enables 3D measurement that is highly accurate, dense, and fast. However, this measurement is only possible for the wrapped phase value, which has ambiguities in its multiples of cycles. Two particular problems are that conventional methods require additional patterns to be projected to determine the absolute phase and that unwrapping the phase tends to fail where depth varies abruptly. Two methods are proposed: the first is to determine the absolute phase without additional patterns being projected by observing the projected pattern with multiple cameras and applying the geometric constraints between them, and the second is to prevent failure in unwrapping the phase by referring to continuities in the relative phases of multiple projected patterns. The proposed methods were achieved with a 3D scanner that can measure approximately a 180 degrees field of view within 0.5 s, with an accuracy of 0.14 mm in depth.     

Development of novel thermoelectric materials by reduction of lattice thermal conductivity

Thermal conductivity is one of the key parameters in the figure of merit of thermoelectric materials. Over the past decade, most progress in thermoelectric materials has been made by reducing their thermal conductivity while preserving their electrical properties. The phonon scattering mechanisms involved in these strategies are reviewed here and divided into three groups, including (i) disorder or distortion of unit cells, (ii) resonant scattering by localized rattling atoms and (iii) interface scattering. In addition, we propose construction of a ‘natural superlattice’ in thermoelectric materials by intercalating an MX layer into the van der Waals gap of a layered TX₂ structure which has a general formula of (MX)_1+x(TX₂)_n (M=Pb, Bi, Sn, Sb or a rare earth element; T=Ti, V, Cr, Nb or Ta; X=S or Se and n=1, 2, 3). We demonstrate that one of the intercalation compounds (SnS)_1.2(TiS₂)₂ has better thermoelectric properties compared with pure TiS₂ in the direction parallel to the layers, as the electron mobility is maintained while the phonon transport is significantly suppressed owing to the reduction in the transverse phonon velocities.     

On-chip cell sorting system using laser-induced heating of a thermoreversible gelation polymer to control flow

We have developed a microfabricated fluorescence-activated cell sorter system using a thermoreversible gelation polymer (TGP) as a switching valve. The glass sorter chip has Y-shaped microchannels with one inlet and two outlets. A biological specimen containing fluorescently labeled cells is mixed with a solution containing a thermoreversible sol-gel polymer. The mixed solution is then introduced into the sorter chip through the inlet. The sol-gel transformation was locally induced by site-directed infrared laser irradiation to plug one of the outlets. The fluorescently labeled target cells were detected with sensitive fluorescence microscopy. In the absence of a fluorescence signal, the collection channel is plugged through laser irradiation of the TGP and the specimens are directed to the waste channel. Upon detection of a fluorescence signal from the target cells, the laser beam is then used to plug the waste channel, allowing the fluorescent cells to be channeled into the collection reservoir. The response time of the sol-gel transformation was 3 ms, and a flow switching time of 120 ms was achieved. Using this system, we have demonstrated the sorting of fluorescent microspheres and Escherichia coli cells expressing fluorescent proteins. These cells were found to be viable after extraction from the sorting system, indicating no damage to the cells.     

High-intensity multi-bunch beam generation by a photo-cathode RF gun

A multi-bunch photo-cathode RF gun system has been developed as an electron source for the production of intense quasi-monochromatic X-rays based on inverse Compton scattering. The desired multi-bunch beam is 100 bunches/pulse with a total charge of 500 nC and a bunch spacing of 2.8 ns. We modified the gun cavity of a ‘BNL-type IV’ RF gun to allow a CsTe cathode plug in the end plate. The system uses a four-dipole chicane beam line to allow the injection of laser light normal to the cathode surface. We compensate the gun cavity beam loading caused by the high-intensity multi-bunch electron beam by injecting the laser pulse before RF power has filled the cavity. We have achieved a total intensity of 220 nC in 100 bunches with a bunch-to-bunch energy spread under 1.3% (peak-to-peak). This paper concentrates on experiments to generate the high-intensity multi-bunch beam with compensation of the bunch-to-bunch energy spread due to heavy beam loading.     

Growth of Cu2ZnSnS4 thin films on Si (100) substrates by multisource evaporation

Cu₂ZnSnS₄ films were grown on Si (100) by vacuum evaporation using elemental Cu, Sn, S and binary ZnS as sources. X-ray diffraction patterns of films grown at different substrate temperatures indicated that polycrystalline growth was suppressed and the orientational growths were relatively induced in a film grown at higher temperatures. Tetragonal structure of Cu₂ZnSnS₄ films was confirmed by studying RHEED patterns. The existence of c-axis ([001] direction) growth, two kinds of a-axis (〈100〉 direction) growth and four kinds of {112} twins which can be classified as two symmetrical pairs is proposed. Broad emissions at around 1.45 eV and 1.31 eV were observed in the photoluminescence spectrum measured at 13 K.     

The long-term results of percutaneous isolated hepatic perfusion for patients with advanced hepatocellular carcinoma

We studied the long-term outcome of percutaneous isolated hepatic perfusion (PIHP) for patients with hepatocellular carcinoma. This study included 31 patients with Stage IVA and 5 with IVB disease treated by PIHP until December, 1997. The mean age and tumor diameter were 55 and 7.7 cm, respectively. Twenty-two had portal vein invasion, 13 had hepatic vein invasion, and all patients had multiple intrahepatic metastases of more than 5 tumor foci. The PIHP with adriamycin or cisplatin was undertaken in a total of 50 treatments in these 36 patients. CR was observed in 6 and PR in 13 with an overall response rate of 59%, excluding 4 patients who were not evaluable. Five of 6 patients with CR remain free of disease at 7 to 54 months after the first treatment. The overall survival rate was 67% at 1 year and 32% at 5 years. The survival rates of Stage IVA patients (1-year = 71%, 5-year = 36%) were higher than Stage IVB patients (1-year = 20%, 5-year = 0%). The 5-year survival rates of patients with vascular invasion (Vp1-3 = 23%, Vv1-3 = 8%) were lower than those without it (Vp0 = 47%, Vv0 = 51%). These results indicated that PIHP achieved a 5-year survival rate of approximately 40% in patients with multiple advanced hepatocellular carcinoma in the absence of distant organ metastases and marked vascular invasion, and yielded complete long-term remission in some of these patients.     

Prevention of marrow graft rejection without induction of graft-versus-host disease by a cytotoxic T-cell clone that recognizes recipient alloantigens

In allogeneic marrow transplantation, donor T cells that recognize recipient alloantigens prevent rejection but also cause graft-versus-host disease (GVHD). To evaluate whether the ability to prevent marrow graft rejection could be dissociated from the ability to cause GVHD, we generated a panel of four different CD8 cytotoxic T-lymphocyte clones specific for H2(d) alloantigens. Three of the clones caused no overt toxicity when as many as 20 x 10(6) cells were infused intravenously into irradiated H2(d)-positive recipients, and one clone caused acute lethal toxicity within 1 to 3 days after transferring 10 x 10(6) cells into H2(d)-positive recipients. One clone that did not cause toxicity was able to prevent rejection of (C57BL/6J x C3H/HeJ)F1 marrow in 800 cGy-irradiated (BALB/cJ x C57BL/6J)F1 recipients without causing GVHD. Large numbers of cells and exogenously administered interleukin-2 were required to prevent rejection. These results with different CD8 clones suggest that GVHD and prevention of rejection could be separable effects mediated by distinct populations of donor T cells that recognize recipient alloantigens.     

Magnetic resonance imaging in the diagnosis of jejunal leiomyoblastoma

We report a case of large leiomyoblastoma of the jejunum. The sagittal views in pre-operative magnetic resonance imaging (MRI) indicated that a cystic tumor with solid component was present, sequential from the small bowel. We suspected a smooth muscle tumor of the small bowel, but did not rule out the malignancy. The operative diagnosis was smooth muscle tumor of the proximal jejunum, and partial resection of the small bowel was performed. The pathological examination revealed benign leiomyoblastoma of the jejunum without metastasis. MRI contributed to the pre-operative diagnosis of the origin of this rare tumor, in a non-invasive fashion.