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A beneficial effect of argon (Ar) ion bombardment for crystalline silicon (c-Si) surface passivation has been studied. Experiments of an Ar plasma treatment over an hydrogenated amorphous silicon (a-Si:H) layer grown on c-Si are performed, where an a-Si:H layer is prepared at different levels of defect density. Interestingly, the c-Si surface passivation is improved by an Ar plasma treatment for a defect-rich, i.e. low-quality, a-Si:H layer, while it is deteriorated by the treatment for a low-defect, i.e. high-quality, a-Si:H layer. The improvement of passivation is discussed in terms of microstructural changes of a-Si:H, associated with redistribution of hydrogen, where mobile hydrogens play an important role.

Interface defects in state-of-the-art semiconductors have a strong impact on device performance. These defects are often generated during device fabrication, in which a variety of plasma processing is used for deposition, etching and implantation. Here, we present the ion-induced defects in hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) heterojunction. The experiments of argon ion (Ar+) irradiation over an a-Si:H/c-Si stack are systematically performed. The results suggest that the defects are generated not only by the impact of Ar+ (i.e. well-known effects), but also by another unique effect associated with “hot” mobile hydrogens (H). The mobile H atoms generated near the a-Si:H surface by the impact of Ar+ diffuse deeper, and they generate the a-Si:H/c-Si interface defects such as dangling bonds. The diffusion length of mobile H is determined to be 2.7 ± 0.3 nm, which indicates efficient reactions of mobile H with weak bonds in an a-Si:H network structure.

In the present study, TONS504 (C51H58N8O5I2; molecular weight, 1,116.9), a novel cationic hydrophilic photosensitizer, was synthesized from protoporphyrin IX dimethyl ester through a five‑step process according to a patented method for use in photodynamic therapy (PDT). The subcellular localization of TONS504 and the cytotoxic effects of TONS504‑mediated PDT in the mouse mammary tumor EMT6 cell line were investigated. TONS504 was localized primarily in the lysosomes and partially in the mitochondria. The cytotoxic effects of TONS504‑mediated PDT in the mouse mammary tumor EMT6 cell line were investigated using a WST8 assay and an Oxidative Stress kit. The cell viability values following treatment with 10 µg/ml TONS504 at light energies of 0, 1, 5 and 10 J/cm2 were 92.5, 101.8, 27.7 and 1.8%, respectively. The percentages of reactive oxygen species (ROS)(+) cells following the same treatment were 8.6, 8.5, 29.2 and 70.1%, respectively, whereas the percentages of apoptotic cells were 7.1, 5.6, 24.8 and 48.7%, respectively. The percentages of ROS(+) and apoptotic cells in the group subjected to TONS504‑mediated PDT increased in a manner dependent on the TONS504 concentration and light energy. Further studies are required to evaluate the in vivo pharmacokinetics, tissue distribution and photodynamic effects of TONS504.

Passivating antireflection coating of crystalline silicon has been experimentally studied using a three-layered stack, consisting of an i/n a-Si:H/SiN trilayer. The passivation property is characterized by the minority carrier lifetime, which shows ≳ 1 ms for the i/n a-Si:H/SiN trilayer prepared at a temperature as low as 250 ∘C. The antireflection property is confirmed by a reflection of light of ≲ 2.0% at 550 nm and a low reflection in a wide range of visible and near-infrared regions, which is adequate for solar cell application, particularly in back-contact structure. The roles of each layer are discussed in terms of the chemical and field-effect passivation as well as the antireflection property. The optoelectronic properties of a neat SiN layer are also discussed to achieve a stable and reliable antireflection performance under the low-temperature growth conditions.

Electronic defects in semiconductor devices play important roles in device performance and reliability. These defects are created during fabrication using plasma-based processing technology. The authors investigate the generation and annihilation of defects in amorphous silicon by measuring the photocurrent during processing with hydrogen and argon plasmas. Unfavorable species for defect generation and favorable species for defect recovery are distinguished. These results are beneficial for improving semiconductor plasma processing, which is used to make state-of-the-art devices such as FinFETs, computer memory, and solar cells.

Carrier trapping in hydrogenated amorphous silicon (a-Si:H) has been investigated by means of an optical pump-probe technique. The trapped carriers (electrons) at the conduction band tail are detected as an increment of the photocurrent, and their density is quantitatively determined under the assumption of carrier generation and recombination kinetics. We find that carrier trapping strongly depends on the band tail distribution in addition to the pump light intensity. Specifically, the trapped electron density increases with the Urbach energy that characterizes the valence band tail broadening. Under the condition of a pump light intensity of 10 mW/cm2 operated at 532 nm, the trapped electron density is determined to be ≈ 4 × 1017 cm− 3 for an intrinsic a-Si:H film with an Urbach energy of 45 mV. The effects of carrier trapping on the device performance are studied in single-junction a-Si:H p-i-n solar cells. The results suggest that carrier trapping causes a reduction in the fill factor of the solar cells.

Surface passivation of crystalline silicon (c-Si) is experimentally studied during the growth of a hydrogenated amorphous silicon (a-Si:H) and epitaxial silicon (epi-Si) passivation layer at a subnanometer to nanometer scale. The property of surface passivation is monitored in real time via in situ measurement of a photocurrent in c-Si under plasma-enhanced vapor deposition for the passivation layer growth. The measurement results suggest the following. Passivation is improved by the growth of an a-Si:H layer, where a large band offset is formed at the a-Si:H/c-Si interface, and the carrier recombination is suppressed. On the other hand, passivation is deteriorated with the growth of an ultrathin epi-Si layer ( d ≲ 2.5 ± 1.0 nm) because the band offset is not formed at the interface, and plasma-induced defects are created in c-Si. However, passivation is improved with a thick epi-Si layer ( d ≳ 2.5 ± 1.0 nm), where the band bending is formed near the epi-Si/c-Si interface, which partially suppresses the carrier recombination. The suppression of the plasma-induced defects as well as the formation of the band offset are important for surface passivation.

We fabricated 20-layer-stacked Ge/Si 1− x C x quantum dots (QDs) by solid source molecular beam epitaxy, for the realization of Si-based, strain-compensated Ge QDs. We inserted 2-nm-thick Si mediating layers between the Ge QDs and the Si 1− x C x strain-compensating spacer layers (SCLs) and evaluated their influence on the structural and optical properties of the obtained system. High density QDs with a size fluctuation of approximately 14% were successfully maintained independent of the number of stacked layers in the case of QDs with Si mediating layers, while the QD size monotonically increased with a number of stacked layers in the case of QDs without Si mediating layers. The sheet density of QDs with Si mediating layers reached 1.2×10 11 cm −2 . A strong photoluminescence (PL) emission with a line-width of 96.7 meV was obtained for the QDs with Si mediating layers. The improvement of the aforementioned properties was caused by both the absence of C bonds at the surface and the improved surface roughness obtained by introducing Si mediating layers. The QD size increased for the 20-layer-stacked Ge/Si QDs samples grown with 10-nm-thick spacer layers, due to the accumulation of internal strains. By contrast, the size distribution of QDs was almost constant for the range of spacer layer thicknesses used in the present work (between 10 nm and 40 nm), implying that the tensile-strained Si 1− x C x SCLs compensated a certain fraction of the strain field created by the compressive-strained Ge QDs.

We examined the influence of the processing temperature on hydrogenated amorphous Si/crystalline Si0.3Ge0.7 heterojunction solar cells with a bandgap of 1.0 eV, which were grown on Si(001) by solid-source molecular beam epitaxy. Stepwise, compositionally graded buffer Si1−xGex layers were applied to prepare Si0.3Ge0.7 films with low dislocation density. We studied the influence of the annealing temperature applied at the buffer layer on the diode characteristics. The diode factor was minimized to 1.45 at 800 °C, and the saturation current density monotonically decreased from 7.5×10−4 A/cm2 for an annealing temperature of 650 °C to 5.0×10−5 A/cm2 for that of 900 °C, as a result of the promotion of dislocation annihilation. Consequently, the Si0.3Ge0.7 heterojunction solar cell showed a maximum conversion efficiency of 1.50% when the annealing temperature was 850 °C. We also studied the influence of the growth temperature of the p-Si0.3Ge0.7 active layer (absorber) on the cell performance. The short circuit current density increased from 16.03 mA/cm2 for 520 °C to 20.95 mA/cm2 for 600 °C. This result corresponded to an improvement of quantum efficiency response in the longer wavelength region due to the reduction of crystal defects caused by oxygen contamination. However, the Si0.3Ge0.7 active layer processed at a higher temperature showed an accumulation of threading dislocations and roughening of the surface, resulting in the degradation of both the open circuit voltage and the fill factor.

New disodium mercaptoundecahydro-closo-dodecaborate (BSH)-conjugated chlorin derivatives 11, 12, 16 and 20 as agents for both photodynamic therapy (PDT) and boron neutron capture therapy (BNCT) of cancer were synthesized. The in vivo biodistribution and clearance of 11, 12, 16 and 20 were investigated in tumor-bearing mice. Compounds 12 and 16 showed good tumor-selective accumulation among the four derivatives. The time to maximum accumulation of compound 16 in tumor tissue was one-fourth of that of compound 12, and clearance from normal tissues of compound 16 was similar to that of compound 12. The in vivo therapeutic efficacy of PDT using 16, which has twice as many boron atoms as 12, was evaluated by measuring tumor growth rates in tumor-bearing mice with 660 nm light-emitting diode irradiation at 6h after injection of 16. Tumor growth was significantly inhibited by PDT using 16. These results suggested that 16 is a good candidate for both PDT and BNCT of cancer.

Background The lipophilic photosensitizer, TONS 501, is a novel porphyrin-derived methyl ester that was developed for photodynamic antimicrobial chemotherapy. This study developed a hydrophilic and anionic porphyrin salt of this compound (TONS 501-Na) for use in photodynamic therapy (PDT). This chlorin derivative is synthesized from the protoporphyrin IX dimethyl ester. Materials and methods We investigated the in vitro cytotoxic effects of TONS 501-Na-mediated PDT on EMT6 mouse breast cancer cells. EMT6 cells were incubated with 0-100 μg/ml TONS 501-Na for 24 h prior to replacing the culture medium and exposing the cells to 6 mW/cm2 diode laser irradiation at 0-13 J/cm2 to induce PDT. Morphological changes and cell viability were evaluated 24 h after PDT. The percentages of apoptotic cells were evaluated 4 h and 24 h after PDT. Results The concentrations of TONS 501-Na that killed 50% of EMT6 cells after exposure to light doses of 0, 0.4, 3, 6, or 13 J/cm2 were 84.6, 33.2, 18, 8.2, and 2.2 μg/ml, respectively. Tumor cells exposed to PDT showed chromatin condensation and fragmentation. The percentages of apoptotic cells increased in a TONS 501-Na concentration-dependent manner in the PDT group, and were significantly higher than those in the control group or in cells treated with TONS 501-Na or laser irradiation alone. Conclusion TONS 501-Na-mediated PDT induced mouse breast cancer cell death in a concentration-dependent manner. Future studies should evaluate the in vivo pharmacokinetics, tissue distribution, and photodynamic effects of TONS 501-Na.

We have studied the effect of the deposition rate on the structural and optical characteristics of five-layer-stacked Ge self-assembled quantum dots (QDs) on a Si (001) substrate grown by molecular beam epitaxy. Ge QDs were formed using a pulse growth technique, which consists of high-rate Ge deposition and an interruption in growth. In this work, the deposition rate was varied from 1.1 A/s to 2.8 A/s. Pyramid-shaped QDs with a monomodal size distribution were obtained at 2.8 A/s, while a bimodal size distribution including pyramid-shaped QDs and multifaceted dome-shaped QDs was observed between 1.1 A/s and 2.2 A/s. As a result, an improved size fluctuation of 11.1% and highest sheet density of 5.6 × 10 10 cm − 2 were achieved for the QD sample grown at 2.8 A/s. As for the optical characteristics, a single photoluminescence (PL) emission line at 0.825 eV with a width of 86.1 meV was observed at 12 K. Furthermore, we found that the PL emission from the Ge QDs shows type-II emission characteristics, i.e., the shift of the PL peak energy with respect to the PL excitation power ( P exc ) was proportional to P exc 1/3 .

New boron-containing chlorin derivatives 9 and 13 as agents for both photodynamic therapy (PDT) and boron neutron capture therapy (BNCT) of cancer were synthesized from photoprotoporphyrin IX dimethyl ester ( 2 ) and l -4-boronophenylalanine-related compounds. The in vivo biodistribution and clearance of 9 and 13 were investigated in tumor-bearing mice. The time to maximum accumulation of compound 13 in tumor tissue was one-fourth of that of compound 9 , and compound 13 showed rapid clearance from normal tissues within 24 h after injection. The in vivo therapeutic efficacy of PDT using 13 was evaluated by measuring tumor growth rates in tumor-bearing mice with 660 nm light-emitting diode irradiation at 3 h after injection of 13 . Tumor growth was significantly inhibited by PDT using 13 . These results suggested that 13 might be a good candidate for both PDT and BNCT of cancer.

Defects in hydrogenated amorphous silicon (a-Si:H)/crystalline silicon (c-Si) heterojunction have been detected via in situ photocurrent measurement during growth of a-Si:H and consecutive postannealing. During growth, defects are generated not only in the a-Si:H layer but also in c-Si. The defects in the a-Si:H layer are completely recovered by postannealing, whereas those in c-Si are partially recovered; the residual defects are formed in c-Si. Interestingly, the postannealing induces the formation of the interface defects at a-Si:H/c-Si, which may deteriorate the performances of a-Si:H/c-Si heterojunction solar cells.

Electronic defects in crystalline silicon induced by hydrogen plasma treatments are studied, based on in-situ photocurrent measurements and real-time spectroscopic ellipsometry. The electronic defects are generated by the plasma treatments, and annihilated partially by postannealing. The generation and annihilation of defects strongly depends on both the treatment time and the annealing temperature. A long-time plasma treatment results in the formation of the residual defects in the silicon bulk. The density of these defects is estimated to be of the order of 1013 cm−2. Interestingly, the electronic defects are formed even before a strong modification of the surface structure, i.e., the formation of a nanometer-scale disordered surface layer.

In this study, we fabricated strain-relaxed Si 0.58 Ge 0.42 thin films on Si substrates by molecular beam epitaxy (MBE) for heterojunction solar cell applications. A combined set of stepwise Si 1− x Ge x buffer layers and a Si 0.51 Ge 0.49 strain-inverted layer, in conjunction with rapid thermal annealing (RTA), were employed to confine the dislocations within the buffer layers. Structural characterization of the samples revealed a low dislocation density of less than 10 5 cm −2 and a relatively smooth surface (0.903 nm in root mean square roughness). The results of solar cell characterization showed both an extended absorption edge (1200 nm) and improved diode characteristics. For these cells, the short-circuit current density, open-circuit voltage, fill factor, and efficiency were 8.25 mA cm −2 , 233 mV, 0.509, and 0.98%, respectively.

Three new water-soluble chlorin derivatives 3 , 5 and 8 for potential use as photosensitizers in photodynamic therapy (PDT) for cancer were synthesized from photoprotoporphyrin IX dimethyl ester ( 1 ). The in vivo biodistribution and clearance of chlorin derivatives 3 , 5 and 8 were investigated in tumor-bearing mice. Iminodiacetic acid derivative 8 showed the greatest tumor-selective accumulation among the new chlorin derivatives with maximum accumulation in tumor tissue at 3 h after intravenous injection and rapid clearance from normal tissues within 24 h after injection. The in vivo therapeutic efficacy of PDT using 8 was evaluated by measuring tumor growth rates in tumor-bearing mice with 660 nm light-emitting diode irradiation at 3 h after injection of 8 . Tumor growth was significantly inhibited by PDT using 8 . These results indicate that iminodiacetic acid derivative 8 is useful as a new photosensitizer to overcome the disadvantages of photosensitizers that are currently in clinical use.

Details of light-induced annealing of hole trap state in undoped hydrogenated amorphous silicon (a-Si:H) have been studied; it has been found that prolonged illumination significantly reduces the density of hole trap states in the energy range deeper than 0.5 eV, and subsequent thermal annealing increases the density of hole trap states and restored the sample to the initial state before the illumination. We can speculate, from the experimental results and discussion in this work, that defect conversion processes are taking place during the long exposure to light; Si dangling bonds are generated from the precursors or latent sites which manifested as hole trap states located between 0.5 and 0.7 eV from the top of the valence band.

Surface passivation has been recognized as a crucial step in the evaluation of minority carrier lifetime of photovoltaic materials as well as in the fabrication of high efficient solar cells. Dilute acids of HF and HCl are employed for germanium (Ge) surface passivation. An effective lifetime of passivated Ge wafers has been evaluated by a microwave photoconductive decay (μ-PCD) measurement. Surface recombination velocities, S , of H- and Cl-terminated Ge surfaces are 23 and 37 cm/s, respectively. The stability of passivated Ge surfaces against exposure to air has also been examined. The HCl-passivated Ge surfaces are found to be more robust than HF-passivated surfaces.

A method to fabricate metal nanostructures by transfer printing, applicable to textured surfaces, is described. The key is the use of self-assembled polystyrene-block-poly-2-vinylpyridine thin films as binding layers. The plasmonic properties of the obtained metal (Ag) nanostructures showed the potential of this method in the design of novel devices.

Internal photoemission (IPE) has been successfully applied to evaluate band offsets of heterojunctions (HJs) in crystalline silicon (c-Si)-based solar cells. Tunneling of carriers through the potential spike at HJ and the presence of a carrier conduction path in the wide-band-gap material of HJ can affect the IPE results. In other words, IPE measures the effective band discontinuity, including effects of the carrier conduction path. This feature of IPE is suited for the characterization of solar-cell structures. Results obtained for hydrogenated amorphous silicon/c-Si HJ and gallium phosphide/c-Si HJ are presented and discussed.

Low-temperature n-type silicon epitaxial growth has been studied for the application to n+/p homojunction solar cells. Epitaxial Si films can be grown at the substrate temperatures from room temperature (RT) to 200 °C by plasma-enhanced chemical vapor deposition. Two-step growth is effective for obtaining high-quality layers above 150 °C. In this growth, a very thin Si layer has been deposited on Si substrates at a low hydrogen-to-silane gas-flow ratio, and subsequently an epitaxial Si layer has been grown at a higher ratio. Smooth nucleation with reduced local stress has been enhanced in the initial stage of the epitaxial growth. An open-circuit voltage, Voc, of 0.610 V and a conversion efficiency, η, of 13.54% have been obtained for an n+/p cell, where the n+ layer was deposited at 200 °C. Film growth mode changes below 100 °C. The stress in the film during the epitaxial growth is relieved by introducing a small fluctuation of crystal orientation and the voids in the film at these temperatures. We have succeeded in fabricating a solar cell with a Voc of 0.608 V and an η of 13.52% having an n+ layer deposited at RT.

To improve the efficacy of sonodynamic therapy of cancer using photosensitizers, we developed a novel porphyrin derivative designated DCPH-P-Na(I) and investigated its photochemical characteristics and sonotoxicity on tumor cells. DCPH-P-Na(I) exhibited a minimum fluorescent emission by excitation with light, compared with a strong emission from ATX-70, which is known to reveal both photo- and sonotoxicity. According to this observation, when human tumor cells were exposed to light in the presence of DCPH-P-Na(I) in vitro, the least phototoxicity was observed, in contrast to the strong phototoxicity of ATX-70. However, DCPH-P-Na(I) exhibited a potent sonotoxicity on tumor cells by irradiation with ultrasound in vitro. This sonotoxicity was reduced by the addition of L-histidine, but not D-mannitol, thus suggesting that singlet oxygen may be responsible for the sonotoxicity of DCPH-P-Na(I). DCPH-P-Na(I) demonstrated significant sonotoxicity against a variety of cancer cell lines derived from different tissues. In addition, in a mouse xenograft model, a potent growth inhibition of the tumor was observed using sonication after the administration of DCPH-P-Na(I) to the mouse. These results suggest that sonodynamic therapy with DCPH-P-Na(I) may therefore be a useful clinical treatment for cancers located deep in the human body without inducing skin sensitivity, which tends to be a major side-effect of photosensitizers.

It is known that the combination of laser light and its sensitizer is effective for noninvasive tumor treatment, referred to as photodynamic therapy. Using the combination of ultrasound and its sensitizer has also been suggested for a similar kind of tumor treatment, referred to as sonodynamic therapy. The purpose of this paper is to obtain such sensitizers accumulating selectively in tumors. Amphiphilic derivatives of rose bengal (RB) were synthesized to add a tumor-accumulating property to RB. One type of the synthesized RB derivatives (RBD3), having an alkyl chain with a branching carboxyl group, was found to be superior in amphiphilicity to the other types. Tumor tissue distribution of the synthesized derivatives in mice bearing colon 26 carcinoma was evaluated. It was found that RBD3s with carbon chain lengths of 12, 14, and 16 had higher concentrations in the tumor tissue than RB by more than 1 order of magnitude, several hours after administration. The concentrations correlated well with their water/1-octanol partition coefficients. Since RB is known to induce in vitro cell damage in combination with either laser light or ultrasound, the newly synthesized amphiphilic RB derivatives may be potentially useful as a tumor-selective sensitizer for both light and ultrasound.

Recent study revealed that photodynamic therapy (PDT) with a novel photosensitizer (ATX-S10(Na)) shows more potent effects for various skin diseases than ALA-PDT. The effect of ATX-S10(Na)-PDT on dermal fibroblasts is still unknown. Using dermal fibroblasts derived from normal and scleroderma patients, and mouse skin in vivo, we compared the effects of ATX-S10(Na)-PDT and ALA-PDT. Fibroblasts from normal, scleroderma patients or mice skin were treated with ATX-S10(Na)-PDT or ALA-PDT. After the PDT treatments, the expression of matrix metalloproteinases (MMPs) Tissue inhibitors of metalloproteinases (TIMPs) and collagen synthesis was assayed using ELISA and reverse transcription-PCR (RT-PCR). The expression of MMP-1 and MMP-3 was slightly decreased and collagen I mRNA was significantly increased in scleroderma fibroblasts compared with normal fibroblasts. Both ATX-S10(Na)-PDT and ALA-PDT increased the expression of MMP-1 and MMP-3 in protein and mRNA levels in both normal and scleroderma fibroblasts with more potent effect by ATX-S10(N)-PDT. Collagen I synthesis was markedly decreased by ATX-S10(Na)-PDT and by ALA-PDT again with more potent effect by ATX-S10(Na)-PDT in both normal and scleroderma fibroblasts. In mice skin the effect of PDT for MMPs and collagen I was also detected and the effect was more potent in ATX-S10(Na)-PDT. In contrast, MMP-2, TIMP-1, TIMP-2, and collagen III expression was not affected by the ATX-S10(Na)-PDT or ALA-PDT treatment. ATX-S10(Na)-PDT is more potent modulator for dermal matrix components than ALA-PDT and might be useful for scleroderma patients.

We demonstrate the polarization-dependent laser oscillation of a biphenyl-capped thiophene crystal based on stimulated resonance Raman scattering (SRRS) at room temperature. Under optical excitation at resonant absorption wavelengths, a platelet single crystal shows amplified spontaneous emission (ASE) with a full width at half maximum (FWHM) of ~5 nm. This ASE intensity is increased at the polarization perpendicular to the crystal face [i.e., transverse magnetic (TM) mode]. When excitation wavelengths approach the absorption edge, the single crystal emits a pair of further narrowed emission lines (FWHM < 0.5 nm) due to a transition into the SRRS regime. The intensity of the SRRS line at 1455 cm-1 is selectively increased at the polarization parallel to the crystal face [i.e., transverse electric (TE) mode]. On the other hand, the SRRS line at 1596 cm-1 is propagated in the TM mode. This polarization-dependent SRRS phenomenon is related to the coherent molecular vibrations in the uniaxially oriented single crystal.

New chlorin derivatives were synthesized from protoporphyrin IX dimethyl ester ( 1 ) as a starting material. The tumor-localizing abilities were determined by bathochromic and hyperchromic shift test using albumin and the photosensitivities were evaluated by photooxidation test using dansyl- l -methionine. NOH-P-H ( 3 ) was the most excellent in the both tests. NOH-P-H ( 3 ) was conjugated with aspartic acid to evaluate the biodistribution with the time progress by nitrogen pulsed laser spectrofluorometry. The concentration of NOH-P-Asp ( 15 ) in cancer tissues showed the highest concentration at 6 h after the administration and corresponded to five to seven times in other organs. The concentration in cancer tissues showed a rapid decrease at 24 h after the administration. PDT effect of NOH-P-Asp ( 15 ) was evaluated using tumor-bearing mice. Remarkable anti-tumor effect was observed. NOH-P-Asp ( 15 ) was expected to be applicable to a new photosensitizer for PDT.

Eleven Ga-phorphyrin complexes bearing various lengths of carbon-chain were synthesized and the UV–vis spectra shift patterns in various concentrations of albumin solutions were evaluated. The distributions of these derivatives into the organs were also determined by surface fluorescence using nitrogen-pulsed laser spectrophotometry. The shift patterns between 0 and 0.9% albumin concentrations (albumin test) were correlated to their tumor localizing property. The albumin test was proved to be useful for evaluation of tumor localizing properties of porphyrin derivatives. The tumor localizing ability was increased along with increasing their lipophilicity and the derivative bearing decyl groups as side chains was a maximum. The porphyrin–albumin complex might have key mission for the passive accumulation focusing on the tumor.

Two kinds of convenient photosensitivity screening methods (Methods A and B) were established to find new photosensitizers for photodynamic therapy (PDT). Method A is based on oxidation mechanism of cholesterol and types I and II can be specified. Method B is performed using dansyl- l -methionine and offers the benefits of fast response time. Various porphyrin, chlorin and phthalocyanine derivatives were synthesized and subjected to the screening methods. The assays have yielded similar results. The results were also identical to the photosensitivity (Ga > Zn > Mn-complex) of water-soluble metalloporphyrins bearing the same side chains. Therefore, the Methods A and B were thought to be appropriate as screening methods to find lead compounds of photosensitizers for PDT.

We have studied Ge self-assembled quantum dots (QDs) grown by molecular beam epitaxy on Si (001) substrates. We investigated the effect of a pulse growth technique, which involves the combination of a high deposition rate of 2.8 A/s and a 5-s growth interruption (GI) time, on the properties of 20-layer stacked Ge QDs. We found that both the size and size dispersion of the QDs grown using the pulse growth technique were successfully maintained without generating any dislocations even after 20 layers of stacking. Further, a high sheet density of 6.9×10 10 cm −2 and better size dispersion of 12.4% can be achieved. In photoluminescence (PL) measurements, PL emission at 0.833 eV with line width of 71.2 meV was clearly observed at 12 K for 20-layer stacked Ge QDs grown using the pulse growth technique.

We investigated the structural properties of 2-μm thick Si 0.58 Ge 0.42 thin films grown on a combined set of Si 1− x Ge x stepwise buffer layers and a Si 0.51 Ge 0.49 strain-inverted layer on Si substrates. Raman spectroscopy and Rutherford backscattering measurements showed smaller residual strain and superior crystalline lattice ordering compared to a sample without any buffer layer. Furthermore, a Si 0.58 Ge 0.42 thin film with a low dislocation density of less than 10 5 cm −2 and a smooth surface roughness of 0.903 nm can be achieved by using a combined set of Si 1− x Ge x stepwise buffer layers and a Si 0.51 Ge 0.49 strain-inverted layer, because most dislocations can be confined within each Si 1− x Ge x buffer layer.

We have fabricated silicon nanocrystals with different dimensions by the thermal annealing and thermal oxidation of ultrathin hydrogenated amorphous silicon (a-Si:H) films (2–10nm) deposited by thermal chemical vapor deposition. Dimensions of silicon nanodots are the function of thickness of the ultrathin a-Si:H film. Therefore, we can change the dimensions of silicon nanodots (3–10nm) by varying the a-Si:H film thickness according to our requirements. From our experimental studies, we have drawn a calibration curve of required a-Si:H film thickness against the average dimension of fabricated crystalline grains.

Background/purpose: Photodynamic therapy (PDT) is a promising treatment for various skin tumors and other skin diseases. We investigated the potential therapeutic effects of PDT using ATX-S10(Na) ointment and a diode laser in mouse skin models of experimental skin tumors as well as transplanted human samples of superficial skin tumors and lesional psoriatic skin. Methods: ATX-S10(Na) ointment (1% w/v) was introduced into tape-stripped mouse skin, transplanted squamous cell carcinoma (SCC) samples and human skin diseases after topical application, then PDT was performed. Results: ATX-S10(Na) ointment (1% w/v) was introduced effectively into tape-stripped mouse skin and transplanted SCC samples after topical application, but was not detected after 48 h, as assessed by fluorescence microscopy. PDT, using 1% ATX-S10(Na) ointment and diode laser (50 J/cm2), was found to decrease epidermal thickness in 12-0-tetradecanoylphorbol-13-acetate (TPA)-treated mouse skin by 6 days. PDT with 1% ATX-S10(Na) ointment and diode laser (150 J/cm2) was also effective for transplanted SCC, and tumors were eliminated by 6 weeks. PDT against Bowen disease, basal-cell carcinoma, and psoriasis xenografts onto SCID mice also showed marked suppression of tumor growth and cell proliferation, respectively. Conclusion: Our results indicate that ATX-S10(Na)-PDT is an effective treatment for various skin tumors and psoriasis in experimental mouse models.

Photodynamic therapy (PDT) is a potent treatment for skin tumors. Although the therapeutic effect of PDT is supposed to be due to cellular cytotoxicity, the precise mechanism is still unknown. ATX-S10(Na) [13,17-bis(1-carboxypropionyl)carbamoylethyl-8-ethenyl-2-hydroxy-3-hydroxyiminoethylidene-2,7,12,18-tetramethylporphyrin sodium salt], a novel hydrophilic chlorin photosensitizer, shows good accumulation in tumors and is suitable for use in PDT. In this study, we investigated the mechanism of PDT-induced cell death using ATX-S10(Na).. Following ATX-S10(Na) treatment for 12 h, normal human keratinocytes (NHK) were irradiated using a diode laser. PDT-induced cell death and the activity of various caspases were measured. Activation of Fas antigen was also determined by immunoprecipitation analysis. The expression of Bax, cytochrome c, and apoptosis-inducing factor (AIF) was determined by Western blotting.ATX-S10(Na)-PDT had induced apoptosis of NHK by 2 h and the maximal effect was observed at 6 h following irradiation. The effect was suppressed by pretreatment of NHK with inhibitors of caspases 3, 6, 8 and 9. A caspase activity assay revealed the sequential activation of caspases 8, 3 and 6, and caspases 9, 3 and 6, respectively. Immunoprecipitation analysis indicated multimerization of Fas antigen without Fas ligand binding in ATX-S10(Na)-PDT-treated NHK. Western blotting revealed cytosolic release of cytochrome c and AIF accompanied by decreased Bax expression in the cytosol.ATX-S10(Na)-PDT induces apoptosis of NHK, and this was mediated by sequential activation of two caspase cascades, caspases 8, 3 and 6, and caspases 9, 3 and 6. This was accompanied by multimerization of Fas antigen and cytosolic release of cytochrome c and AIF.

Ultrasonically induced cell damage and active oxygen generation with 4-formyloximeetylidene-3-hydroxyl-2-vinyl-deuterio-porphynyl(IX)-6-7-diaspartic acid (ATX-S10) were compared in the same in vitro insonation setup. Sarcoma 180 cells suspended in air-saturated PBS were exposed to ultrasound at 2 MHz for up to 60 s in the presence and absence of ATX-S10. The viability was determined by Trypan blue exclusion test. Ultrasonically induced active oxygen generation in the presence and absence of ATX-S10 in air-saturated aqueous solutions of 50 mM 2,2,6,6-tetramethyl-4-piperidone was detected by electron spin resonance (ESR). Significant enhancement of the rates of both ultrasonically induced cell damage and nitroxide generation was demonstrated with 40-160 microM ATX-S10. Both rates correlated very well. The enhancement of both rates with ATX-S10 was suppressed by 10 mM histidine. These results suggest that ultrasonically generated active oxygen plays a primary role in the ultrasonically induced cell damage in the presence of ATX-S10.

The effect of initial low temperature grown buffer (LT buffer) layer thickness on GaAs on Si grown by conventional two-step growth method for molecular beam epitaxy has been investigated. The grown layers have been characterized by photoluminescence (PL), double crystal X-ray diffraction (XRD) and atomic force microscopy (AFM). It is indicated that the crystalline quality and the root-mean-square (RMS) roughness of thick GaAs layer on Si depends on the thickness of initial low temperature grown nucleation buffer layer. The present investigation confirms that the initial layer should be sufficiently thick to obtain good quality smooth layers of GaAs on Si substrate. The FWHM of heavy-hole band emission was as low as 4.8 meV for the samples with initial nucleation layer of around 200 nm. The AFM study revealed that the RMS roughness of the thick GaAs layer on Si is large for the samples with thin initial nucleation layer. Also, the annealed LT buffer layers indicate a similar RMS roughness tendency instead of almost constant RMS roughness for the as-grown LT buffer layers. They suggest that the macroscopic surface morphologies and the film quality of the stressed heteroepitaxial layer are dominated during the heating steps of the initial LT buffer layer.

湛水直播栽培では稲株の基部が地表近くの浅い土壌に位置するために稲体が株基から倒れる「ころび型倒伏」が生じ易い. そこでまず, 国内外の特徴的な20品種を圃場で2ヶ年にわたり栽培し, 出穂後10日から14日に押し倒し抵抗値を測定した. その結果, 1穂当たりの押し倒し抵抗値は2ヶ年の平均で0.56∼2.58Nで, 大きな品種間差異を認めた. 2ヶ年の押し倒し抵抗値は互いに高い正の相関関係にあったことから, この結果は各品種の遺伝的特性を示していると考えられた. そこでこれら20品種のうち, 押し倒し抵抗値が大きかった関東PL12と, 中程度であったM401, および小さかったキヌヒカリを選んで, 出穂後10日における冠根の伸長角度を調べたところ, 0∼18°の浅い角度で伸びる冠根数は, 関東PL12がM401およびキヌヒカリよりも多かった. 次に圃場で押し倒し抵抗値を測定した20品種について, 幼植物の冠根形質を調べた. 半球形の金属ネットを用いたバスケット法により, 播種後23日における幼植物の冠根の伸長角度を水平 (0°) から垂直 (90°) まで5等分して測定した結果, 押し倒し抵抗値が大きい品種は, 幼植物において36∼54°に伸長する冠根数が多いことが明らかになった. また押し倒し抵抗値と, 幼植物の太い冠根の引っ張りによる破断強度および冠根直径との間にも有意な正の相関関係があった. これらの結果から, 幼植物の36∼54°に伸長する冠根数および冠根の破断強度により, 品種の耐ころび型倒伏性を早期に検定できる可能性があることがわかった.

The performance of a newly developed potential tumor-seeking magnetic resonance (MR) contrast agent α-Aqua-13,17-bis(1-carboxypropionyl) carbamoylethyl-3,8-bis(1-phenethyloxyethyl)-β-hydroxy-2,7,12,18-tetramethyl-porphyrinato manganese (III) (HOP-8P) was tested using a mouse model. Tumor-bearing (SCC-VII) mice were imaged using a 1.5T MR imager before and after intravenous administration of 0.1 mmol/kg of HOP-8P. A biodistribution analysis was performed using an optical emission spectrometer. Significant enhancement of the transplanted tumor was observed in MR images 24 h after intravenous injection of HOP-8P. The biodistribution assessment of manganese also correlated with the results of the imaging study. During the 24-h period following contrast administration, HOP-8P was consistently cleared from the circulation, liver, kidneys, and muscle; however, it was progressively accumulated within the tumor. HOP-8P is a promising tumor-seeking metalloporphyrin MR contrast agent with a wide imaging window. Magn Reson Med 47:549–553, 2002. © 2002 Wiley-Liss, Inc.

Background We observed red autofluorescence emanating from bronchial cancer lesions using a sensitive color-fluorescence endoscopy system. We investigated to clarify the origin of the red autofluorescence. Methods The wavelengths of the red autofluorescence emanating from lesions were measured in eight patients using a spectrum analyzer and compared based on pathologic findings. Red autofluorescence at 617.3, 617.4, 619.0, and 617.1 nm was emitted by normal bronchus, inflamed tissue, tissue exhibiting mild dysplasia, and malignant lesions, respectively. Protoporphyrin, uroporphyrin, and coproporphyrin, the major porphyrin derivatives in human blood, were purchased to determine which porphyrin derivative is the source of red fluorescence when acquired de novo. We synthesized photoporphyrin, Zn-protoporphyrin and Zn-photoprotoporphyrin from protoporphyrin. Results Coproporphyrin and uroporphyrin emitted only weak fluorescence. Fluorescence was emitted by our synthesized Zn-photoprotoporphyrin at 625.5 nm and by photoprotoporphyrin at 664.0 nm. Conclusions From these results, we conclude that Zn-photoprotoporphyrin was the source of the red autofluorescence observed in bronchial lesions. Zn-protoporphyrin is converted to Zn-photoprotoporphyrin by radiation with excitation light. Our results suggest that red autofluorescence emanating from Zn-photoprotoporphyrin in human tissues could interfere with photodynamic diagnosis using porphyrin derivatives such as Photofrin® and Lazerphyrin® with a sensitive endoscopy system, because color cameras cannot differentiate Zn-photoprotoporphyrin red fluorescence from that of other porphyrin derivatives.