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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.

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.

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.

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.

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.

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.

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 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.

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 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.

Carbon doping for p -type GaP and GaPN using carbon tetrabromide (CBr4) source in rf plasma molecular beam epitaxy was investigated. The doping concentration could be easily controlled by adjusting CBr4 pressure, and a wide region of hole concentration form ∼1017 to ∼1019 cm-3 was obtained in both GaP and GaPN. It was found that the activation ratio of carbon in GaPN is lower than that in GaP. The hole concentration and mobility in GaPN do not change with nitrogen content at a wide region from 0.5 to 3%. The Hall mobility values in GaP and GaPN were ∼120 and ∼50 cm2/Vs at a hole concentration of ∼1 × 1017 cm-3. Photoluminescence measurement show that the carbon incorporation reduces the intensity of luminescence, and the relative peak intensity decreases with the increase of hole concentration. This implies the existence of carbon-related defects that quench the luminescence (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Gallium(III) tetraphenylporphyrin (GaTPP) was found to act as an ionophore for valproate, an agent widely used for anti-epileptic therapy. An electrode constructed using GaTPP and bis(1-butylpentyl)decane-1,10-diyl diglutarate (ETH 469) as a membrane solvent in a poly(vinyl chloride) membrane matrix exhibited a near-Nernstian response to valproate in the concentration range 5×10–5–1×10–2 M with a slope of –55 mV per concentration decade in a buffer solution containing 0.1 M 2-morpholinoethanesulfonic acid (MES)-NaOH (pH 5.5). The lower limit of detection was 20 µM. The electrode displayed the following selectivity sequence: valproate>salicylate> SCN–>benzoate>ClO4–≈F–>NO2–>CH3COO–≈I–>Cl–>NO3–. This electrode was applied to the determination of valproate levels in deproteinized serum samples.

ATX-S10(Na), a hydrophilic chlorin photosensitizer having an absorption maximum at 670 nm, is a candidate second-generation photosensitizer for photodynamic therapy (PDT) for cancer treatment. In this study, we examined plasma protein binding, cellular uptake and subcellular targets of ATX-S10(Na) in vitro. Protein binding ratios of 50 microg / ml ATX-S10(Na) in rat, dog and human plasma were 73.0%, 87.2% and 97.7%, respectively. Gel filtration chromatography revealed that 1 mg / ml ATX-S10(Na) bound mainly to high-density lipoprotein (HDL) and serum albumin at the protein concentration of 0.4%, with binding ratios of 46% and 36%, respectively. The free form of ATX-S10(Na) was mostly incorporated into T.Tn cells, and its cellular uptake was partially but significantly inhibited by endocytosis inhibitors such as phenylarsine oxide, chloroquine, monensin and phenylglyoxal, and by chilling the cells to 4 degrees C. However, ouabain, harmaline, sodium cyanide, probenecid and aspartic acid did not influence the uptake of ATX-S10(Na), suggesting that cellular uptake of ATX-S10(Na) was not related to sodium-potassium pump activity, sodium-dependent transporter activity, mitochondrial oxidative respiration, organic anion transporter activity or aspartic acid transporter activity. By fluorescence microscopy, lysosomal localization of ATX-S10(Na) was observed in T.Tn cells. However, electron microscopic observation revealed that many subcellular organelles such as mitochondria, endoplasmic reticulum, ribosomes, Golgi complex and plasma membrane were damaged by PDT using 25 microg / ml ATX-S10(Na) soon after laser irradiation at 50 J / cm(2), and tumor necrosis was rapidly induced. This result indicated that ATX-S10(Na) was widely distributed within the cell.

ATX-S10(Na), a hydrophilic chlorin photosensitizer having an absorption maximum at 670 nm, is a candidate second-generation photosensitizer for use in photodynamic therapy (PDT) for cancer treatment. The effectiveness of PDT using ATX-S10(Na) and a diode laser for experimental tumors was evaluated in vitro and in vivo. In-vitro PDT using ATX-S10(Na) and the diode laser showed drug concentration-, laser dose- and drug exposure time-dependent cytotoxicity to various human and mouse tumor cell lines. In Meth-A sarcoma-implanted mice, optimal PDT conditions were found where tumors were completely eliminated without any toxicity. Against human tumor xenografts in nude mice, the combined use of 5 mg / kg ATX-S10(Na) and 200 J / cm(2) laser irradiation 3 h after ATX-S10(Na) administration showed excellent anti-tumor activity, and its efficacy was almost the same as that of PDT using 20 mg / kg porfimer sodium and a 100 J / cm(2) excimer dye laser 48 h after porfimer sodium injection. Microscopic observation of tumor tissues revealed that PDT using ATX-S10(Na) and the diode laser induced congestion, thrombus and degeneration of endothelial cells in tumor vessels, indicating that a vascular shutdown effect plays an important role in the anti-tumor activity of PDT using ATX-S10(Na) and the diode laser.

A new boronated porphyrin compound (STA-BX909) was developed as a possible agent for boron neutron capture therapy. The boron concentration was measured by an in vivo rat experimental brain tumor model and an in vitro cell culture study. This agent was compared to sodium borocaptate (BSH) which has been used in clinical trials of boron neutron capture therapy. In the 9L rat brain tumor model, STA-BX909 achieved a higher boron tumor/blood ratio 24 h after injection in comparison to BSH. A boron concentration study in cultured glioma cell lines (U-251, U-87, 9L) demonstrated an increased boron concentration as a function of exposure time to STA-BX909, while the boron concentration remained stable with increasing exposure time to BSH. Use of a colony forming assay with thermal neutron irradiation revealed more cytotoxicity with STA-BX909 than BSH when the same concentration of 10B was administered. We concluded that STA-BX909 may be an effective drug for use in boron neutron capture therapy and that it merits further investigation.

We investigate Si nanocrystals fabricated by the rapid thermal oxidation (RTO) of an ultrathin chemical vapour deposition (CVD) amorphous Si (a-Si:H) film. It is found from the transmission electron microscope (TEM) observation that the ultrathin RTO film contains Si nanocrystals of around or less than 5 nm in size. The dynamic electrical conduction measurement of the RTO diode structure including the Si nanocrystals reveals novel features such as the N-shaped tunnel current versus gate voltage characteristics and the hysteresis. It is also found that the gate voltages at the first and second current rise are fixed and the current reduction in the fixed time interval is observed at the constant gate voltage. These findings can be explained by the fixed-amount electron charging effect at the Si nanocrystals and the consequent screening effect on the tunnel current flowing through the diode structure.

We used a two-color analysis system to assess the porphyrin uptake and DNA content in four established cell lines of glioma employing flow cytometry (FCM). The FCM study revealed porphyrin uptake in all cells, regardless of the phase of the cell cycle they were in. However, those in the G0/G1 phase showed moderate uptake of porphyrin and those in the G2/M phase showed a higher uptake. These results indicated the advantage of using porphyrin as the carrier of tumor targeting agents as a therapeutic strategy for malignant tumors.

We synthesized a radiosensitizer KADTF, consisting of a hypoxic radiosensitizer, KU2280, bound to the side chain group of Mn-metalloporphyrin, which accumulates in tumor tissue. In the in vitro colony-forming activity test using HeLa cells, KADTF enhanced the effect of radiation under hypoxic conditions. Radiation therapy at 20 Gy, 1.5 h after infusion of KADTF (0.15 mM/kg), inhibited tumor growth more markedly than did a single radiation treatment. A clear tumor MR images of the SCCVII tumor was obtained at 1.5 h after administration of KADTF (0.1 mM/kg).

Experimental studies and numerical analysis have been carried out to clarify the relationship between carrier diffusion lengths and defect density in undoped a-Si:H. It has been confirmed that in device quality plasma-deposited a-Si:H, the diffusion lengths of both electrons and holes under steady-state illumination of the intensity equivalent to normal solar cell operating conditions are determined by the density of Si dangling-bond defects ranging between 3×1015 and 8×1016 cm−3. This rather trivial result, however, has not been obtained in previous studies in which the carrier transport data obtained by the steady-state photocarrier grating method were treated incorrectly. The ratio of the drift mobility of electrons to that of holes and the ratio of electron lifetime to the hole lifetime in a-Si:H under illumination have been determined and their implications discussed.

The time-of-flight photoconductivity technique has been employed to evaluate the electron and hole drift mobility in a-Si:H samples prepared with varying energy-of-ion-bombardment during growth. The values of the room temperature measured hole drift mobility increases from conventional values of ≈ 0.004 cm2/V s up to ≈ 1 cm2/V s. The corresponding electron drift mobility increases from ≈ 1 cm2/V s to ≈ 60 cm2/V s. This increase is accompanied by a decrease of the mobility activation energy and an increase in its field dependence. Low-frequency capacitance—voltage measurements reveal that there is no significant change of the mid-gap defect density.

The phase separation states of hemicellulose and lignin in their blends were investigated by means of contact angle measurements. The hysteresis behavior in dynamic contact angles suggested that a phase separation of cluster-state type (not of random dispersion type) took place at hemicellulose-rich and lignin-rich mixing ratios. It may be caused by the low cohesive force between hemicellulose and lignin molecules. Further, the total surface tension, and the balance between dispersion and polar forces in the total surface tension were evaluated from the equation of Wu. It was found that in the region of a hemicellulose-rich mixing ratio, the polar and dispersion forces of the surface tension of the solid were reduced and raised, respectively, and in contrary to this, in the lignin-rich region, the former were raised and the latter were reduced. The polymer-polymer interaction parameter of Flory between hemicellulose and lignin depends on the mixing ratio as reported previously ; this may be ascribed to a difference of the balancing of polar-dispersion forces.

We evaluated changes in hematology and chemical profile, and the tissue retention of hematoporphyrin derivative (HpD) following the intravenous injection in dogs. HpD at concentrations of 1, 5, 10, and 15 mg/kg was intravenously injected to 16 dogs (n=4 each) and complete blood count (CBC) and blood chemistry were performed on days 1, 3, 5, and 7 after the injection. To examine tissue retention, HpD (5 mg/kg) was administered to 15 dogs and 3 dogs were euthanized on days 1, 2, 7, 14, and 28 after the injection, respectively, to collect the skin, muscle, small intestine, spleen, kidney and liver as tissue samples. There were no significant changes in CBC and blood chemical profile except for an increase in LDH concentrations in dogs given 10 and 15 mg/kg of HpD at day 3. The levels of HpD retention in the tissues were ranked in the following order: liver > kidney > spleen > intestine > muscle > skin.

We spectrochemically analyzed 12 Ga-Metal porphyrins (Ga-Cn-P) with different degrees of hydrophobicity, and observed a close association between the in vivo Ga-Cn-P localization in the tumor and its affinity to transferrin and LDL. Image analysis of tumors with 99m-Tc-STA-R12, a porphyrin-scintigraphic agent, revealed STA-R12 localization in the tumor tissue alone about 1 h after intravenous infusion. Our results suggest the importance of endocytosis mediated by transferrin as well as LDL that have been reported as a mechanism of the tumor-localizing activity of porphyrin.

The viscoelasticity of the hydrogels, the moisture sorption, and the characteristics of the sorbed water of highly water-absorptive hydroxyethylcellulose (HEC) graft copolymers [e.g., HEC graft copolymers containing partially hydrolyzed polyacrylamide (HEC-P-Hyd-PAM), etc.] were investigated in comparison with commercial absorbents. The viscosity (η) and the rigidity (G) of the dispersions of their hydrogels were, respectively, proportional to the second to the sixth powers and the fifth to the seventh powers of their concentrations (η = KC2–6 and G = K′C5–7). With respect to the characteristics of the sorbed water, the conductivity of 0.1 N KCI in the hydrogels of the HEC water, absorbents was about 11.8 mS/cm, which was almost the same as that of 0.1 N KCI in pure water, and the water absorbency of dry matter (soybean seeds) in their hydrogels was almost the same as that in pure water. These results suggest that most of the sorbed water in the HEC super water absorbents behaves like free water. The maximum volume of sorbed moisture in a monolayer fashion (Vm) of HEC-P-Hyd-PAM analyzed using the Brunauer-Emmett-Teller equation was about 0.21 g/g (1.2 mol water/polymer repeat unit), and there was no cluster water at 92% relative humidity or below as a result of applying the cluster function concept. © 1995 John Wiley & Sons, Inc.

The structures of the hydrogels of the partially hydrolyzed cellulose-graft-polyacrylamide copolymers as super water absorbents were examined by use of a cryogenic scanning electron microscope. The hydrogel of the wood pulp graft copolymer that had been not hydrolyzed (P/PULP-AM) formed a spongelike structure with numerous circular micropores. The highly swollen hydrogel of the partially hydrolyzed wood pulp graft copolymer (P/PULP-AM-Hyd), on the other hand, formed a honeycomblike structure with polygonal pores surrounded with membraneous walls. A hydrogel of a crosslinked polyacrylamide (PAM) formed a similar structure to that of P/PULP-AM, but the honeycomblike structure shown in P/PULP-AM-Hyd was not observed in the partially hydrolyzed PAM. The pore size of the honeycomblike structure of the hydrogel of P/PULP-AM-Hyd decreased with an increase in the amount of the crosslinker added at graft copolymerization. For the hydrogel of the P/PULP-AM-Hyd with less addition of the crosslinker, however, the honeycomblike structure had been broken. The hydrogel of the P/PULP-AM-Hyd without the addition of the crosslinker did not show a honeycomblike structure. In spite of no addition of the crosslinker, the cellulosic film and nonwoven fabric graft copolymers formed honeycomblike structures. © 1994 John Wiley & Sons, Inc.

The partially hydrolyzed graft copolymers of crosslinked polyacrylamide (PAM) on water-soluble hydro-xyethylcelluloses(HECs) with different molecular chain lengths were synthesized by using of the ceric ion in-itiation method in an aqueous medium, and the effect of the molecular chain length of the HEC trunk polymer on the swelling behavior of the graft copolymer (HEC-AM-Hyd) was investigated. The synthesized HEC-AM-Hyds were similar to one another in the proportion of the HEC trunk polymer and the grafted branch polymer and in the crosslinking density and content of carboxyl groups of the partially hydrolyzed PAM branch polymer. The absorbency of HEC-AM-Hyd increased with an increase in the molecular cahin length of the HEC trunk polymer. The HEC-AM-Hyd from the HEC with longer chain length had higher resistibility against the decrease in the absorbency with an increase in the NaCl concentration than that from the HEC with shorter chain length. It is con-sidered that the HEC molecule that has high rigidity and extends largely in water acts effectively in the swelling of HEC-AM-Hyd, and that the superior swelling properties of the HEC-AM-Hyd from the HEC with longer chain length are due to the larger extension of its trunk polymer.

Quinhydrone/methanol treatment for the measurement of carrier lifetime in crystalline silicon substrates has been investigated. To estimate the surface passivation effect, the lifetimes of the silicon substrates were measured using the microwave photoconductive decay method. The measured lifetime is dependent on quinhydrone concentration and passivation time. The 0.01 mol/dm3 quinhydrone/methanol treatment exhibited a good passivation effect, and a very low surface recombination velocity was obtained. The quinhydrone/methanol treatment can provide a reliable lifetime map of silicon wafers since a constant lifetime value without degradation can be obtained. Therefore, the quinhydrone/methanol treatment can be used for estimating the bulk lifetime of silicon substrates.

We have fabricated nanocrystalline dots by thermal annealing (TA) of thermal chemical-vapor-deposited amorphous silicon (a-Si:H) films. In S. Hazra, I. Sakata, M. Yamanaka, and E. Suzuki, Appl. Phys. Lett. 80, 1159 (2002), we observed that ultrathin a-Si:H films (2–10 nm) are stressed because of the presence of deformed crystallites or paracrystallites. With the increase of thickness, volume fraction of paracrystallites decreased in the films and stress in the films gradually reduced. Therefore, by changing the thickness, we can control the stress in the a-Si:H films and thereby the dimensions (in the range of 5 to 10 nm) as well as volume fractions of nanocrystallites formed by TA. On the other hand, it has been found that relaxed a-Si:H networks form polycrystalline films by TA.

To obtain the morphology of ultrathin hydrogenated amorphous silicon (a-Si:H) films with thicknesses of 2–10 nm grown by thermal chemical-vapor deposition, we have utilized spectroscopic ellipsometry and introduced a model, called the fine crystalline grain model. This model resolves that the growth of the amorphous silicon matrix starts with the formation of dense deformed crystallites or paracrystallites. A better fit to the experimental data has been obtained with this model when the a-Si:H film thickness is below 20 nm. The fine grain component gradually decreases with the film growth. It has been clarified that the presence of deformed crystallites in the starting a-Si:H films acts as a constraint for their crystallization by rapid thermal annealing.

Crystalline SiGe layers with Ge contents from 10 to 80 % were grown on Si (100) substrates by molecular beam epitaxy for the applications in Si-based multijunction thin film solar cells. The effects of different buffer layers on the structural and electrical properties of SiGe layers were studied in detail. It was found that the gradient SiGe buffer formed at a lower limit temperature of 400°C was effective in reducing the threading dislocations, and in turn improving the surface morphology and Hall mobility. a-Si/SiGe heterojunction solar cells were fabricated on metallic-like Si substrates to testify the suitability of SiGe layers for solar cell applications. E ff = 0.75% and V oc = 320 mV were achieved at a Ge content of 8%, and 0.5% and 200 mV at 57 %. Hydrogenation for SiGe layer improved V oc to 430 mV for the same Ge content of 8 %.

We synthesized and developed a new tumor imaging agent, 111In-labeled metalloporphyrin (111In-ATN-10) which consists of a carrier (ATN-10) of the tumor imaging possessing both a non-radioactive manganese complex in the porphyrin ring and a bifunctional chelating group (DTPA) attached to its side chain. The images of the three kinds of tumors were delineated more clearly by 111In-ATN-10 than 67Ga-citrate. Moreover, there was no photosensitivity in ATN-10. 111In-ATN-10 is studied as a new tumor positive scintigraphic agent instead of 67Ga-citrate.