Free-Standing Electrode and Fixed Surface Tiny Electrode Implemented Triboelectric Nanogenerator with High Instantaneous Current

Conventional triboelectric nanogenerators (TENGs) face challenges pertaining to low output current density at low working frequencies and high internal impedance. While strategies, such as surface modification to enhance surface charge density, permittivity regulation of materials, and circuit management, have partially mitigated these issues. However, they have also resulted in increased complexity in the fabrication process. Therefore, there is an urgent demand for a universal and simplified approach to address these challenges. To fulfill this need, this work presents a free-standing electrode and fixed surface tiny electrode implemented triboelectric nanogenerator (FFI-TENG). It is fabricated by a straightforward yet effective method: introducing a tiny electrode onto the surface of the tribo-negative material. This approach yields substantial enhancements in performance, notably a more than tenfold increase in output current density, a reduction in effective working frequencies, and a decrease in matching resistance as compared to vertical contact-separation TENGs (CS-TENGs) or single-electrode TENGs (SE-TENGs). Simultaneously, a comprehensive examination and proposition regarding the operational mechanism of FFI-TENG, highlighting its extensive applicability are also offered. Significantly, FFI-TENG excels in mechanical energy harvesting even under ultra-low working frequencies (0.1 Hz), outperforming similar contact-separation models. This innovation positions it as a practical and efficient solution for the development of low-entropy energy harvesters.

Multicrystalline Informatics Applied to Multicrystalline Silicon for Unraveling the Microscopic Root Cause of Dislocation Generation

A comprehensive analysis of optical and photoluminescence images obtained from practical multicrystalline silicon wafers is conducted, utilizing various machine learning models for dislocation cluster region extraction, grain segmentation, and crystal orientation prediction. As a result, a realistic 3D model that includes the generation point of dislocation clusters is built. Finite element stress analysis on the 3D model coupled with crystal growth simulation reveals inhomogeneous and complex stress distribution and that dislocation clusters are frequently formed along the slip plane with the highest shear stress among twelve equivalents, concentrated along bending grain boundaries (GBs). Multiscale analysis of the extracted GBs near the generation point of dislocation clusters combined with ab initio calculations has shown that the dislocation generation due to the concentration of shear stress is caused by the nanofacet formation associated with GB bending. This mechanism cannot be captured by the Haasen-Alexander-Sumino model. Thus, this research method reveals the existence of a dislocation generation mechanism unique to the multicrystalline structure. Multicrystalline informatics linking experimental, theoretical, computational, and data science on multicrystalline materials at multiple scales is expected to contribute to the advancement of materials science by unraveling complex phenomena in various multicrystalline materials.

Hydrogenation of silicon-nanocrystals-embedded silicon oxide passivating contacts

We investigate the effect of hydrogen passivation of dangling bonds in silicon oxide passivating contacts with embedded silicon nanocrystals (NAnocrystalline Transport path in Ultra-thin dielectrics for REinforced passivation contact, NATURE contact). We first investigated the differences in electrical properties of the samples after hydrogen gas annealing and hydrogen plasma treatment (HPT). The results show that the NATURE contact was efficiently passivated by hydrogen after HPT owing to the introduction of hydrogen radicals into the structure. Furthermore, we examined the dependence of process parameters such as HPT temperature, duration, and H2pressure, on the electrical properties and hydrogen depth profiles. As a result, HPT at 500 °C, 15 min, and 0.5 Torr resulted in a large amount of hydrogen inside the NATURE contact and the highest implied open-circuit voltage of 724 mV. Contact resistivity and surface roughness hardly increased when HPT was performed under the optimized condition, which only improved the passivation performance without deteriorating the electron transport properties of the NATURE contact.

Fabrication of light trapping structures specialized for near-infrared light by nanoimprinting for the application to thin crystalline silicon solar cells

Vehicle-integrated photovoltaics (VIPV) are gaining attention to realize a decarbonized society in the future, and the specifications for solar cells used in VIPV are predicated on a low cost, high efficiency, and the ability to be applied to curved surfaces. One way to meet these requirements is to make the silicon substrate thinner. However, thinner substrates result in lower near-infrared light absorption and lower efficiency. To increase light absorption, light trapping structures (LTSs) can be implemented. However, conventional alkali etched pyramid textures are not specialized for near-infrared light and are insufficient to improve near-infrared light absorption. Therefore, in this study, as an alternative to alkaline etching, we employed a nanoimprinting method that can easily fabricate submicron-sized LTSs on solar cells over a large area. In addition, as a master mold fabrication method with submicron-sized patterns, silica colloidal lithography was adopted. As a result, by controlling silica coverage, diameter of silica particles (D), and etching time (t_et), the density, height, and size of LTSs could be controlled. At the silica coverage of 40%, D = 800 nm, and t_et = 5 min, the reduction of reflectance below 65% at 1100 nm and the theoretical short-circuit current gain of 1.55 mA/cm² was achieved.

Bayesian optimization of hydrogen plasma treatment in silicon quantum dot multilayer and application to solar cells

Silicon quantum dot multilayer (Si-QDML) is a promising material for a light absorber of all silicon tandem solar cells due to tunable bandgap energy in a wide range depending on the silicon quantum dot (Si-QD) size, which is possible to overcome the Shockley-Queisser limit. Since solar cell performance is degenerated by carrier recombination through dangling bonds (DBs) in Si-QDML, hydrogen termination of DBs is crucial. Hydrogen plasma treatment (HPT) is one of the methods to introduce hydrogen into Si-QDML. However, HPT has a large number of process parameters. In this study, we employed Bayesian optimization (BO) for the efficient survey of HPT process parameters. Photosensitivity (PS) was adopted as the indicator to be maximized in BO. PS (σ_p/σ_d) was calculated as the ratio of photoconductivity (σ_p) and dark conductivity (σ_d) of Si-QDML, which allowed the evaluation of important electrical characteristics in solar cells easily without fabricating process-intensive devices. 40-period layers for Si-QDML were prepared by plasma-enhanced chemical vapor deposition method and post-annealing onto quartz substrates. Ten samples were prepared by HPT under random conditions as initial data for BO. By repeating calculations and experiments, the PS was successfully improved from 22.7 to 347.2 with a small number of experiments. In addition, Si-QD solar cells were fabricated with optimized HPT process parameters; open-circuit voltage (V_OC) and fill factor (FF) values of 689 mV and 0.67, respectively, were achieved. These values are the highest for this type of device, which were achieved through an unprecedented attempt to combine HPT and BO. These results prove that BO is effective in accelerating the optimization of practical process parameters in a multidimensional parameter space, even for novel indicators such as PS.

Zn1-xGexOy Passivating Interlayers for BaSi2 Thin-Film Solar Cells

BaSi₂ is a promising absorber material for next-generation thin-film solar cells (TFSCs). For high-efficiency TFSCs, a suitable interlayer should be found for every light absorber. However, such an interlayer has not been studied for BaSi₂. In this study, we investigated amorphous Zn_1-xGe_xO_y films as interlayers for BaSi₂. The Zn/Ge atomic ratio in the Zn_1-xGe_xO_y film and the optical band gap depend on the substrate temperature during sputtering deposition. A suitable i-Zn_1-xGe_xO_y/BaSi₂ heterointerface with spike-type conduction band offset was achieved when Zn_1-xGe_xO_y was deposited on BaSi₂ at 50 °C. Furthermore, photoresponsivity measurements revealed that Zn_1-xGe_xO_y has an excellent surface passivation effect on BaSi₂. When the thickness of Zn_1-xGe_xO_y was 2 nm, a high photoresponsivity of 0.9 A/W was obtained for a 500 nm thick BaSi₂ layer at a wavelength of 780 nm under an applied bias voltage of 0.5 V between the front and rear electrodes, where the photoresponsivity in the short-wavelength region was significantly improved compared with that of BaSi₂ capped with an amorphous Si layer. X-ray photoelectron spectroscopy revealed that the Zn_1-xGe_xO_y films suppressed the oxidation of the BaSi₂ surface, decreasing the carrier recombination rate. This is the first demonstration of passivation interlayers for BaSi₂ with suitable band alignment for carrier transport and surface passivation effects.

Data-Driven Optimization and Experimental Validation for the Lab-Scale Mono-Like Silicon Ingot Growth by Directional Solidification

The casting mono-like silicon (Si) grown by directional solidification (DS) is promising for high-efficiency solar cells. However, high dislocation clusters around the top region are still the practical drawbacks, which limit its competitiveness to the monocrystalline Si. To optimize the DS-Si process, we applied the framework, which integrates the growing experiments, transient global simulations, artificial neuron network (ANN) training, and genetic algorithms (GAs). First, we grew the Si ingot by the original recipe and reproduced it with transient global modeling. Second, predictions of the Si ingot domain from different recipes were used to train the ANN, which acts as the instant predictor of ingot properties from specific recipes. Finally, the GA equipped with the predictor searched for the optimal recipe according to multi-objective combination, such as the lowest residual stress and dislocation density. We also implemented the optimal recipe in our mono-like DS-Si process for verification and comparison. According to the optimal recipe, we could reduce the dislocation density and smooth the growth rate during the Si ingot growing process. Comparisons of the growth interface and grain boundary evolutions showed the decrease of the interface concavity and the multi-crystallization in the top part of the ingot. The well-trained ANN combined with the GA could derive the optimal growth parameter combinations instantly and quantitatively for the multi-objective processes.

Effects of grain boundary structure and shape of the solid-liquid interface on the growth direction of the grain boundaries in multicrystalline silicon

We report on the effects of grain boundary (GB) structure on the growth direction of the GBs by utilizing silicon ingots with artificially designed asymmetric tilt GBs. The ingots were...

Effect of the Niobium-Doped Titanium Oxide Thickness and Thermal Oxide Layer for Silicon Quantum Dot Solar Cells as a Dopant-Blocking Layer

Silicon quantum dot (Si-QD) embedded in amorphous silicon oxide is used for p-i-n solar cell on quartz substrate as a photogeneration layer. To suppress diffusion of phosphorus from an n-type layer to a Si-QD photogeneration layer, niobium-doped titanium oxide (TiO_x:Nb) is adopted. Hydrofluoric acid treatment is carried out for a part of the samples to remove the thermal oxide layer in the interface of TiO_x:Nb/n-type layer. The thermal oxide acts as a photo-generated carrier-blocking layer. Solar cell properties using 10-nm-thick TiO_x:Nb without the thermal oxide are better than those with the thermal oxide, notably short circuit current density is improved up to 1.89 mA/cm². The photo-generated carrier occurs in Si-QD with quantum confinement effect. The 10-nm-thick TiO_x:Nb with the thermal oxide layer effectively blocks P; however, P-diffusion is not completely suppressed by the 10-nm-thick TiO_x:Nb without the thermal oxide. These results indicate that the total thickness of TiO_x:Nb and thermal oxide layer influence the P-blocking effect. To achieve the further improvement of Si-QD solar cell, over 10-nm-thick TiO_x:Nb is needed.

A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9

The isolation of qubits from noise sources, such as surrounding nuclear spins and spin-electric susceptibility ^1-4 , has enabled extensions of quantum coherence times in recent pivotal advances towards the concrete implementation of spin-based quantum computation. In fact, the possibility of achieving enhanced quantum coherence has been substantially doubted for nanostructures due to the characteristic high degree of background charge fluctuations ^5-7 . Still, a sizeable spin-electric coupling will be needed in realistic multiple-qubit systems to address single-spin and spin-spin manipulations ^8-10 . Here, we realize a single-electron spin qubit with an isotopically enriched phase coherence time (20 μs) ^11,12 and fast electrical control speed (up to 30 MHz) mediated by extrinsic spin-electric coupling. Using rapid spin rotations, we reveal that the free-evolution dephasing is caused by charge noise-rather than conventional magnetic noise-as highlighted by a 1/f spectrum extended over seven decades of frequency. The qubit exhibits superior performance with single-qubit gate fidelities exceeding 99.9% on average, offering a promising route to large-scale spin-qubit systems with fault-tolerant controllability.

Real-time observation of irradiated HeLa-cell modified by fluorescent ubiquitination-based cell-cycle indicator using synchrotron X-ray microbeam

Fluorescent ubiquitination-based cell-cycle indicator (FUCCI) human cancer (HeLa) cells (red indicates G1; green, S/G2) were exposed to a synchrotron X-ray microbeam. Cells in either G1 or S/G2 were irradiated selectively according to their colour in the same microscopic field. Time-lapse micrographs of the irradiated cells were acquired for 24 h after irradiation. For fluorescent immunostaining, phosphorylated histone proteins (γ-H2AX) indicated the induction of DNA double-strand breaks. The cell cycle was arrested by irradiation at S/G2. In contrast, cells irradiated at G1 progressed to S/G2. The foci were induced in cells irradiated at both G1 and S/G2, suggesting that the G1-S (or S) checkpoint pathway does not function in HeLa cells due to the fact that the cells are functionally p53 deficient, even though X-ray microbeam irradiation significantly induces double-strand breaks. These results demonstrate that single FUCCI cell exposure and live cell imaging are powerful methods for studying the effects of radiation on the cell cycle.

Enhanced photocarrier generation in large-scale photonic nanostructures fabricated from vertically aligned quantum dots

We demonstrate enhanced photocarrier generation using photonic nanostructures fabricated by a wet etching technique with vertically aligned quantum dots (QDs). Using photoluminescence excitation spectroscopy, we found that the photocarrier generation in Ge/Si QDs placed close to the surface is enhanced below the band gap energy of crystalline silicon. The enhancement is explained by light trapping owing to the photonic nanostructures. Electromagnetic wave simulations indicate that the photonic nanostructure with a subwavelength size will be available to light trapping for efficient photocarrier generation by increasing their dip depth.

Enhanced photocarrier generation in large-scale photonic nanostructures fabricated from vertically aligned quantum dots

We demonstrate enhanced photocarrier generation using photonic nanostructures fabricated by a wet etching technique with vertically aligned quantum dots (QDs). Using photoluminescence excitation spectroscopy, we found that the photocarrier generation in Ge/Si QDs placed close to the surface is enhanced below the band gap energy of crystalline silicon. The enhancement is explained by light trapping owing to the photonic nanostructures. Electromagnetic wave simulations indicate that the photonic nanostructure with a subwavelength size will be available to light trapping for efficient photocarrier generation by increasing their dip depth.

Grazing-incidence small-angle X-ray scattering from Ge nanodots self-organized on Si(001) examined with soft X-rays

Grazing-incidence small-angle X-ray scattering (GISAXS) measurements with soft X-rays have been applied to Ge nanodots capped with a Si layer. Spatially anisotropic distribution of nanodots resulted in strongly asymmetric GISAXS patterns in the qy direction in the soft X-ray region, which have not been observed with conventional hard X-rays. However, such apparent differences were explained by performing a GISAXS intensity calculation on the Ewald sphere, i.e. taking the curvature of Ewald sphere into account.

Generation of high photocurrent in three-dimensional silicon quantum dot superlattice fabricated by combining bio-template and neutral beam etching for quantum dot solar cells

We fabricated a three-dimensional (3D) stacked Si nanodisk (Si-ND) array with a high aspect ratio and uniform size by using our advanced top-down technology consisting of bio-template and neutral beam etching processes. We found from conductive atomic microscope measurements that conductivity became higher as the arrangement was changed from a single Si-ND to two-dimensional (2D) and 3D arrays with the same matrix of SiC, i.e., the coupling of wave functions was changed. Moreover, our theoretical calculations suggested that the formation of minibands enhanced tunneling current, which well supported our experimental results. Further analysis indicated that four or more Si-NDs basically maximized the advantage of minibands in our structure. However, it appeared that differences in miniband widths between 2D and 3D Si-ND arrays did not affect the enhancement of the optical absorption coefficient. Hence, high photocurrent could be observed in our Si-ND array with high photoabsorption and carrier conductivity due to the formation of 3D minibands.

Effects of formation of mini-bands in two-dimensional array of silicon nanodisks with SiC interlayer for quantum dot solar cells

A sub-10 nm, high-density, periodic silicon nanodisk (Si-ND) array with a SiC interlayer has been fabricated using a new top-down process that involves a 2D array of a bio-template etching mask and damage-free neutral beam etching. Optical and electrical measurements were carried out to clarify the formation of mini-bands due to wavefunction coupling. We found that the SiC interlayer could enhance the optical absorption coefficient in the layer of Si-NDs due to the stronger coupling of wavefunctions. Theoretical simulation also indicated that wavefunction coupling was effectively enhanced in Si-NDs with a SiC interlayer, which precisely matched the experimental results. Furthermore, the I-V properties of a 2D array of Si-NDs with a SiC interlayer were studied through conductive AFM measurements, which indicated conductivity in the structure was enhanced by strong lateral electronic coupling between neighboring Si-NDs. We confirmed carrier generation and less current degradation in the structure due to high photon absorption and conductivity by inserting the Si-NDs into p-i-n solar cells.

Silicon-based current-injected light emitting diodes with Ge self-assembled quantum dots embedded in photonic crystal nanocavities

Room temperature light emission from Ge self-assembled quantum dots (QDs) embedded in L3-type photonic crystal (PhC) nanocavity is successfully demonstrated under current injection through a lateral PIN diode structure. The Ge QDs are grown on silicon-on-insulator (SOI) wafer by solid-source molecular beam epitaxy (SS-MBE), and the PIN diode is fabricated by selective ion implantation around the PhC cavity. Under an injected current larger than 0.5 mA, strong resonant electroluminescence (EL) around 1.3-1.5 μm wavelength corresponding to the PhC cavity modes is observed. A sharp peak with a quality factor up to 260 is obtained in the EL spectrum. These results show a possible way to realize practical silicon-based light emitting devices.

Simultaneous enhanced photon capture and carrier generation in Si solar cells using Ge quantum dot photonic nanocrystals

We propose a novel solar cell structure with photonic nanocrystals coupled to quantum dots (QDs) for advanced management of photons and carriers. The photonic nanocrystals at the surface create an extra interaction between the photons and the QDs, which promotes light trapping. Photo-generated carriers can be efficiently transported by preparing vertically aligned QDs with electronic coupling. Implementation of the proposed structure was realized in crystalline Si solar cells with Ge QDs by development of a simple and practical formation method based on a wet chemical process without any lithography techniques. The wet process utilizes a periodically modulated etching rate induced by self-organized Ge QDs. The effectiveness of the proposed solar cell was demonstrated by the marked increase of the absolute conversion efficiency when compared with the control crystalline Si solar cells. It is found that light trapping by the photonic nanocrystals has a larger contribution to the efficiency improvement than the contributions from the carrier transport of the vertically aligned QDs.

Configuration and local elastic interaction of ferroelectric domains and misfit dislocation in PbTiO3/SrTiO3 epitaxial thin films

We have studied the strain field around the 90° domains and misfit dislocations in PbTiO3/SrTiO3 (001) epitaxial thin films, at the nanoscale, using the geometric phase analysis (GPA) combined with high-resolution transmission electron microscopy (HRTEM) and high-angle annular dark field--scanning transmission electron microscopy (HAADF-STEM). The films typically contain a combination of a/c-mixed domains and misfit dislocations. The PbTiO3 layer was composed from the two types of the a-domain (90° domain): a typical a/c-mixed domain configuration where a-domains are 20-30 nm wide and nano sized domains with a width of about 3 nm. In the latter case, the nano sized a-domain does not contact the film/substrate interface; it remains far from the interface and stems from the misfit dislocation. Strain maps obtained from the GPA of HRTEM images show the elastic interaction between the a-domain and the dislocations. The normal strain field and lattice rotation match each other between them. Strain maps reveal that the a-domain nucleation takes place at the misfit dislocation. The lattice rotation around the misfit dislocation triggers the nucleation of the a-domain; the normal strains around the misfit dislocation relax the residual strain in a-domain; then, the a-domain growth takes place, accompanying the introduction of the additional dislocation perpendicular to the misfit dislocation and the dissociation of the dislocations into two pairs of partial dislocations with an APB, which is the bottom boundary of the a-domain. The novel mechanism of the nucleation and growth of 90° domain in PbTiO3/SrTiO3 epitaxial system has been proposed based on above the results.

A grazing incidence small-angle x-ray scattering analysis on capped Ge nanodots in layer structures

The grazing incidence small-angle x-ray scattering (GISAXS) intensity from buried Ge nanodots is examined both by GISAXS/reflectivity measurements and by simulations with distorted wave Born approximation (DWBA). The validity and the condition of using the Born approximation (BA) are discussed using simulations based on the layer structures modeled from a reflectivity analysis. As expected in the previous kinematic analysis, use of the BA is reasonable in determining the size and the shape of very small or thin nanodots. Several effects of layer structures on the GISAXS analysis are discussed.

Room-temperature electroluminescence from Si microdisks with Ge quantum dots

A current-injected silicon-based light-emitting device was fabricated on silicon-on-insulator (SOI) by embedding Ge self-assembled quantum dots into a silicon microdisk resonator with p-i-n junction for current-injection. Room-temperature resonant electroluminescence (EL) from Ge self-assembled quantum dots in the microdisk was successfully observed under current injection, and observed EL peaks corresponding to the whispering gallery modes (WGMs) supported by the microdisk resonator were well identified by means of numerical simulations.

[Thymolipoma associated with myasthenia gravis]

A 42-year-old woman was admitted to our hospital complaining of left ptosis, diplopia, and muscle weakness. A diagnosis of myasthenia gravis was made. Chest roentgenograms, computed tomography (CT), and magnetic resonance imaging (MRI) showed a large anterior mediastial mass and suggested thymolipoma. Extended thymectomy was performed via a median sternotomy. Histopathological examination revealed that the tumor consisted of mature adipose tissue and weighed 1,500 grams, in which thymic tissues with Hassall' s corpuscles but without a germinal center were contained. The histological appearance was compatible with a typical thymolipoma. This is the 24th reported case of thymolipoma associated with myasthenia gravis.

Mutagenic and Transforming Effects of Soft-X-rays with Resonance Energy of Phosphorus K-absorption Edge

Syrian golden hamster embryo (SHE) cells were exposed to synchrotron-produced monochromatic X-rays at 5.747 (2.159 keV), 5.763 (2.153 keV) and 5.779 A (2.147 keV). Although X-rays of all wavelengths induced mutations and chromatid aberrations in a dose-dependent manner, when cells were irradiated with 2.153 keV X-rays, which correspond to the resonance energy of the phosphorus K-absorption edge, the frequencies of mutation and chromatid aberration at equal dose levels were higher than for X-rays of the other wavelengths. At equal survival levels, however, there was no difference in the frequencies of mutations and chromatid aberrations in cells irradiated with soft X-rays. On the other hand, the frequency of morphological transformation in cells irradiated with 2.147 keV X-rays was higher than those irradiated with 2.153 keV and 2.159 keV X-rays. The relative biological effectiveness compared to cobalt-60 gamma-rays in morphological transformation was 2.8 for 2.147 keV, 1.1 for 2.159 keV and 1.0 for 2.153 keV at a 37% survival level.

Growth mechanism of Si-faceted dendrites

The growth mechanism of Si-faceted dendrite was studied using an in situ observational technique. We directly observed the growth processes of Si-faceted dendrites from Si melts. It is found that triangular corners with an angle of 60 degrees are formed at the dendrite tip. We present an original growth model for faceted dendrites based on the experimental evidence. The model fully explains the growth process of faceted dendrites.

Irradiation of DNA loaded with platinum containing molecules by fast atomic ions C(6+) and Fe(26+)

PURPOSE

In order to study the role of the Linear Energy Transfer (LET) of fast atomic ions in platinum-DNA complexes inducing breaks, DNA Plasmids were irradiated by C(6+) and Fe(26+) ions.

MATERIAL AND METHODS

DNA Plasmids (pBR322) loaded with different amounts of platinum contained in a terpyridine-platinum molecule (PtTC) were irradiated by C(6+) ions and Fe(26+) ions. The LET values ranged between 13.4 keV/microm and 550 keV/microm. In some experiments, dimethyl sulfoxide (DMSO) was added.

RESULTS

In all experiments, a significant increase in DNA strand breaks was observed when platinum was present. The yield of breaks induced per Gray decreased when the LET increased. The yield of single and double strand breaks per plasmid per track increased with the LET, indicating that the number of DNA breaks per Gray was related to the number of tracks through the medium.

CONCLUSIONS

These findings show that more DNA breaks are induced by atomic ions when platinum is present. This effect increases for low LET heavy atoms. As DSB induction may induce cell death, these results could open new perspectives with the association of hadrontherapy and chemotherapy. Thus the therapeutic index might be improved by loading the tumour with platinum salts.

[Usefulness of dynamic computed tomography for the diagnosis of mediastinal hemangioma]

An asymptomatic 59-year-old female was admitted with an abnormal shadow on her chest radiography. Chest computed tomography (CT) revealed a mass measuring 20 mm in the anterior mediastinum. At the arterial phase on dynamic contrast-enhanced CT (dynamic CT), the pattern of "peripheral puddles", defined as discrete well-defined peripheral enhancing globles, was found in the mass. The tumor was completely resected via a median sternotomy, and was histopathologicaly diagnosed as hemangioma. In this case, dynamic CT was very useful for the preoperative diagnosis, and then the enhancement pattern of "peripheral puddles" on dynamic CT may be a conclusive finding for the diagnosis of mediastinal hemangiomas.

[Surgical treatment for adrenal metastasis from lung cancer]

Several long-term survivors after surgical resection for a solitary adrenal metastasis from non-small cell lung cancer (NSCLC) have been reported in case reports and case series with a small number of patients. We have experienced 6 cases of patients who had adrenalectomy (ADR) for a metastasis from NSCLC. The median survival time (MST) after ADR was 24 months, and there was only 1 case of 3-year survivor. To elucidate the surgical indication and the prognostic factors of patients with a solitary adrenal metastasis from NSCLC, we analyzed 104 patients including our 6 patients who had ADR for a metastasis from NSCLC. The MST after ADR and 5-year survival were 24 months and 31%, respectively. Univariate and multivariate analysis demonstrated that lymph node metastasis at the surgery for primary lung cancer was the only significant and independent predictor of poor survival in patients after ADR. The results suggest that aggressive surgical treatment of a solitary adrenal metastasis from NSCLC may be effective when a patient have N0 disease.

Radiation-induced gamma-H2AX in mammalian cells irradiated with a synchrotron X-ray microbeam

In order to study the radiobiological effects from low dose radiation, a cell irradiation system using synchrotron X-ray microbeam has been developed, by which cells can be recognised individually and irradiated one by one with the desired dose of monochromatic X rays. The minimum beam sizes obtained are 2 microm with the focusing optics and 5 microm square with the non-focused beam, and the beam size can be changed easily with a high-precision slit in the case of a non-focused beam. Human fibroblast cells were individually irradiated with this system, and immunostained by gamma-H2AX antibody to visualise the DNA damage. Most of the fluorescent foci were observed in a localised area in cell nuclei, the size of which was almost the same as the beam size.

Fast He2+ ion irradiation of DNA loaded with platinum-containing molecules

PURPOSE

The association of radiotherapy and chemotherapy is an attractive approach to improve the therapeutic index of the treatment of tumors. A lot of work has been devoted to investigate the effects of X-ray, gamma-ray and neutron irradiation of DNA or living cells loaded with different chemical compounds containing heavy atoms like platinum. No such studies exist presently when fast atomic ions are chosen as ionizing particles. In the present work, we investigate quantitatively the increase of DNA breaks in complexes of plasmid-DNA loaded with platinum atoms under irradiation by fast atomic He2+ ions.

MATERIALS AND METHODS

DNA Plasmids (pBR322) are incubated in solutions containing different concentrations of terpyridine platinum (PtTC). In some preparations, dimethyl sulfoxide (DMSO), a free radical scavenger, has been added in order to investigate the role of the free radicals. The complexes of DNA plasmids loaded with high-Z atoms are irradiated under atmospheric conditions by He2+ ions at an energy of 143 MeV/amu and a linear energy transfert (LET) of 2.24 keV/microm. Analysis of DNA damage--single and double strand breaks--is made by electrophoresis on agarose gels.

RESULTS

The results show a significant increase in DNA strand breaks when platinum is present, indicating a radiosensitization by the high Z atoms. The increase in DNA damages is attributed to inner-shell ionization of a platinum atom by secondary electrons emitted along the He2+ tracks followed by an Auger deexcitation, leading, thus, to a local amplification of the radiative effects close to the DNA. The contributions of scavengeable--solvant mediated--indirect effects and non-scavengeable effects (direct ionization) are quantitatively evaluated.

CONCLUSION

Enhancement of DNA breaks in plasmids loaded with heavy atoms like platinum and irradiated by atomic ions are observed. This finding suggests an enhancement of cell death rate will occur under irradiation by atomic ions when the cells contain high-Z atoms located close to DNA due to the increase of the DNA breaks.

[Pulmonary pleomorphic carcinoma; report of a case]

We report a case of a 64-year-old man with pleomorphic carcinoma of the lung and thymic cyst. He was admitted to our hospital because of an abnormal shadow observed on chest X-ray. Computed tomography (CT) showed a mass lesion located in the right upper lobe and a non-invasive anterior mediastinal tumor adjacent to the left brachiocepharic vein. On enhanced CT, the lung mass showed central low-attenuation areas with a substantial enhancement in the periphery. Preoperative transbronchial blushing cytology of the mass revealed adenocarcinoma. With a diagnosis of primary lung cancer (cT3N0M0) and mediastinal tumor, an operation was performed through a median sternotomy. The mediastinal tumor was excised and a right upper lobectomy and were also accomplished, because the lung tumor did not show adhesion or pleural invasion. Histopathologic examination of the resected specimen revealed that the lung tumor composed of a mixture of spindle and giant cell features and contained a component of adenocarcinoma and squamous cell carcinoma. This finding yielded a pathological diagnosis of pleomorphic carcinoma (pT2N0M0). The mediastinal tumor was diagnosed as thymic cyst. The postoperative course was uneventful, and he is currently well 6 months after surgery.

[Carney triad; report of a case]

We report a case of Carney triad which is very rare disease composed of gastrointestinal stromal tumor (GIST), pulmonary chondroma and paraganglioma. A 15-year-old girl was reffered for treatment with multiple tumors in the left lung. At the age of 13, she underwent total gastrestomy for GIST. At that time multiple pulmonary tumors have already developed and made a diagnosis of chondroma. Progressive enlargement of their size and persistent bloody sputum made her received operation. Finally she underwent left pneumonectomy. In general all 3 tumors have manifested for a long time. Gastric tumors and paragangliomas are often lethal. This shows the necessity of intensive and long-term follow-up.

Enhancement of X-ray-induced breaks in DNA bound to molecules containing platinum: a possible application to hadrontherapy

Complexes made of DNA and chloroterpyridine platinum (PtTC) bound to plasmid DNA were placed in aqueous solution and irradiated with monochromatic X rays tuned to the resonant photoabsorption energy of the L(III) shell of the platinum atom. The number of single- and double-strand breaks (SSBs and DSBs) induced by irradiation on a supercoiled DNA plasmid was measured by the production of the circular-nicked and linear forms. To distinguish the contribution of the direct effects of ionization from the indirect effects due to a free radical attack, experiments were also performed in the presence of a hydroxyl free radical scavenger, dimethyl sulfoxide (DMSO). An enhancement of the number of SSBs and DSBs was observed when the plasmids contained the platinum intercalating molecules. A quantitative analysis was made to evaluate the respective contributions of the direct effects (Auger effect) and the indirect effects (free radical attack) to the number of DNA strand breaks. Even when off-resonant X rays were used, the strand break efficiency remained higher than expected based upon the absorption cross section, suggesting that the platinum bound to DNA might be increasing the yield of strand breaks. A mechanism is suggested that involves photoelectrons generated from the ionization of water which efficiently ionize platinum atoms. If this mechanism is correct, then heavy atoms, with a large cross section for ionization by electrons that are bound to the DNA, should behave as a radiosensitizer. This observation may provide insight into understanding the effects of new radiotherapy protocols, related chemotherapeutic agents such as cisplatin, and conventional radiotherapy for the treatment of tumors. A possible way to deliver the dose selectively in a well-defined volume, which uses the properties of the linear energy transfer of atomic ions interacting with matter, is suggested.

Characterization of a major form of human isatin reductase and the reduced metabolite

Isatin, an endogenous indole, has been shown to inhibit monoamine oxidase, and exhibit various pharmacological actions. However, the metabolism of isatin in humans remains unknown. We have found high isatin reductase activity in the 105,000 g supernatants of human liver and kidney homogenates, and have purified and characterized a major form of the enzyme in the two tissues. The hepatic and renal enzymes showed the same properties, including an M(r) of 31 kDa, substrate specificity for carbonyl compounds and inhibitor sensitivity, which were also identical to those of recombinant human carbonyl reductase. The identity of the isatin reductase with carbonyl reductase was immunologically demonstrated with an antibody against the recombinant carbonyl reductase. About 90% of the soluble isatin reductase activity in the liver and kidney was immunoprecipitated by the antibody. The Km (10 microm) and k(cat)/K(m) (1.7 s(-1) x microm(-1)) values for isatin at pH 7.0 were comparable to those for phenanthrenequinone, the best xenobiotic substrate of carbonyl reductase. The reduced product of isatin was chemically identified with 3-hydroxy-2-oxoindole, which is also excreted in human urine. The inhibitory potency of the reduced product for monoamine oxidase A and B was significantly lower than that of isatin. The results indicate that the novel metabolic pathway of isatin in humans is mediated mainly by carbonyl reductase, which may play a critical role in controlling the biological activity of isatin.

Reparability of lethal lesions produced by phosphorus photoabsorption in yeast cells

The characteristics of DNA lesions produced by the photoabsorption of phosphorus in yeast cells were studied using monochromatized soft X-rays tuned to the absorption peak of the phosphorus K-edge (2153 eV) and below the peak energy (2147 eV). The repaired fractions of DNA double-strand breaks (dsb) were measured relatively by using both a mutant, rad 54-3, which shows the temperature-sensitive dsb repair-deficient phenotype, and a wild-type strain. The repaired fraction of lesion in rad 54-3, which corresponds to the relative yield of dsb reparable by the RAD 54 pathway, was not affected by the phosphorus photoabsorption. Repair of the produced lesions in the wild-type cells was also measured by comparing the surviving fraction of the immediately plated cells to that of those cells plated after holding in a non-nutrient medium for 80 hrs. The recovery of the surviving fraction after the holding treatment was dependent upon the irradiated X-ray energy. These results suggest that irreparable lesions are produced by the inner-shell photoabsorption of phosphorus in DNA, although its yield is small.

Large-scale selection of lines with deletions in chromosome 1 B in wheat and applications for fine deletion mapping

Terminal deletions of chromosome 1B in common wheat were selected on a large scale. The gametocidal gene of Aegilops cylindrica was used as the inducer of chromosome breakage. First, genes for endosperm storage proteins located on both arms of chromosome 1B were used as the selection markers. However, it was found that the chromosome breakage occurred during female gametogenesis, causing genotypic inconsistency between the embryo and endosperm. Thus, we isolated plants with terminal deletions in chromosome 1B by C-banding. Of 1327 plants examined, 128 showed aberrations in chromosome 1B: 47 in the short arm, 76 in the long arm, and 5 in both arms. The present deletions tended to have the breakpoint at more proximal regions than those produced previously by T.R. Endo and B.S. Gill. Using 33 deletion lines produced in this study and 34 lines previously produced, we mapped 39 RFLP loci and a nucleolar organizer region (NOR) on a specific region of chromosome 1B. The NOR was found to consist of two subregions with different repetitive units, which were termed NOR-Bld and NOR-Blp. Based on this fine deletion map and genotypic inconsistency between embryo and endosperm, the features of the gametocidal gene are discussed.

Large-scale selection of lines with deletions in chromosome 1B in wheat and applications for fine deletion mapping

Terminal deletions of chromosome 1B in common wheat were selected on a large scale. The gametocidal gene of Aegilops cylindrica was used as the inducer of chromosome breakage. First, genes for endosperm storage proteins located on both arms of chromosome 1B were used as the selection markers. However, it was found that the chromosome breakage occurred during female gametogenesis, causing genotypic inconsistency between the embryo and endosperm. Thus, we isolated plants with terminal deletions in chromosome 1B by C-banding. Of 1327 plants examined, 128 showed aberrations in chromosome 1B: 47 in the short arm, 76 in the long arm, and 5 in both arms. The present deletions tended to have the breakpoint at more proximal regions than those produced previously by T.R. Endo and B.S. Gill. Using 33 deletion lines produced in this study and 34 lines previously produced, we mapped 39 RFLP loci and a nucleolar organizer region (NOR) on a specific region of chromosome 1B. The NOR was found to consist of two subregions with different repetitive units, which were termed NOR-B1d and NOR-B1p. Based on this fine deletion map and genotypic inconsistency between embryo and endosperm, the features of the gametocidal gene are discussed.Key words: deletion line, gametocidal gene, Triticum aestivum, deletion map, nucleolar organizer region.

Genetic alteration of the beta-catenin gene (CTNNB1) in human lung cancer and malignant mesothelioma and identification of a new 3p21.3 homozygous deletion

The beta-catenin gene (CTNNB1) has been shown to be genetically mutated in various human malignancies. To determine whether the beta-catenin gene is responsible for oncogenesis in thoracic malignancies, we searched for the mutation in 166 lung cancers (90 primary tumors and 76 cell lines), one blastoma and 10 malignant mesotheliomas (two primary tumors and eight cell lines). Among the lung cancers, including 43 small cell lung cancers (SCLCs) and 123 non-small cell lung cancers (NSCLCs), we identified four alterations in exon 3, which is the target region of mutation for stabilizing beta-catenin. One primary adenocarcinoma had a somatic mutation from C to G, leading to an amino acid substitution from Ser to Cys at codon 37. Among the cell lines, SCLC NCI-H1092 had a mutation from A to G, leading to an Asp to Gly substitution at codon 6, NSCLC HCC15 had a mutation from C to T, leading to a Ser to Phe substitution at codon 45, and NSCLC NCI-H358 had a mutation from A to G, leading to a Thr to Ala substitution at codon 75. One blastoma also had a somatic mutation from C to G, leading to a Ser to Cys substitution at codon 37. Among the 10 malignant mesotheliomas, we identified a homozygous deletion in the NCI-H28 cell line. Cloning of the rearranged fragment from NCI-H28 indicated that all the exons except exon 1 of the beta-catenin gene are deleted and that the deletion junction is 13 kb downstream from exon 1. Furthermore, Northern blot analysis of 26 lung cancer and eight mesothelioma cell line RNAs detected ubiquitous expression of the beta-catenin messages except NCI-H28, although Western blot analysis showed that relatively less amounts of protein products were expressed in some of lung cancer cell lines. Our findings suggest that the beta-catenin gene is infrequently mutated in lung cancer and that the NCI-H28 homozygous deletion of the beta-catenin gene might indicate the possibility of a new tumor suppressor gene residing in this region at 3p21.3, where various types of human cancers show frequent allelic loss.

Clinical application of artificial ligament for ankle instability--long-term follow-up

We have applied a reconstructive operation to patients with injury of the lateral ligament in the ankle joint using an artificial ligament made of polyester (Leeds-Keio) since 1985. The operation was performed on 451 feet of 436 patients. Average follow-up period was 5 years and 8 months. Talar tilt and anterior drawer translation before and after the operation were improved from 16 degrees to 4 degrees and from 11 mm to 4 mm, respectively. In this study, which has followed the same patients over an extended period, there were no cases with a decrease in the range of motion of the joint, with further development of osteoarthritis, or with a poorer result than those observed in our earlier study, which reported a short-term follow-up of the same patients. It may therefore be concluded that this reconstructive procedure of the lateral ligament of the ankle joint, using the artificial ligament, is also excellent after long-term follow-up.