Periodic Micropillar-Patterned FTO/BiVO4 with Superior Light Absorption and Separation Efficiency for Efficient PEC Performance

In this study, a high-performance photoanode based on 3D periodic, micropillar-structured fluorine-doped tin oxide (FTO-MP) deposited with BiVO₄ is fabricated using the patterned FTO by direct printing and spray pyrolysis, followed by the deposition of BiVO₄ by sputtering and V ion heat-treatment on the patterned FTO. The FTO-MP enables light scattering owing to its 3D periodic structure and increases the light absorption efficiency. In addition, the high electron mobility of FTO and enlarged surface area of FTO-MP enhance the separation efficiency. Due to the combination of these enhancing strategies, the photocurrent density of micropillar-patterned BiVO₄ at 1.23 V_RHE reached 2.97 mA cm^-2 , which is 67.8% higher than that of flat BiVO₄ . The results suggest that the efficiency can increase significantly using the patterned FTO fabricated by an inexpensive and simple process (i.e., direct printing and spray pyrolysis), thereby indicating a new strategy for the enhancement of efficiency in various energy fields.

The optimization of surface morphology of Au nanoparticles on WO3 nanoflakes for plasmonic photoanode

Among many candidates for photoanode materials of photoelectrochemical (PEC) cell, nanostructured tungsten trioxide (WO₃) is regarded as one of the most promising materials due to its superior electrical properties and adequate bandgap (∼2.8 eV) and band edge position. WO₃ nanoflakes (WO₃ NFs), which have merits on its high surface area and crystallinity, have been actively studied for this manner but solar-to-hydrogen efficiency of WO₃ NFs based photoanode is still not sufficient both in light absorption and charge separation. Plasmon-induced enhancement using Au nanoparticles is excellent approach for both the efficiency of light absorption and charge separation of WO₃. However, it still needs optimization on its amount, shape, coverage, and etc. Here, we synthesized WO₃ NFs by solvothermal growth and decorated gold nanoparticles on these nanoflakes by e-beam evaporation and rapid thermal annealing process in a row. By this process, a large-area AuNPs/WO₃ nanocomposite structure with various size, interparticle distance, and coverage of AuNPs were fabricated. These AuNPs/WO₃ NFs type photoanode achieve high light absorption both in UV and visible range and consequently higher photocurrent density. The optimized AuNPs/WO₃ nanocomposite photoanode exhibits 1.01 mA cm^-2 of photocurrent density, which is increased to 19.8% compared with bare WO₃ nanoflakes. Field emission-scanning electron microscope, x-ray diffraction, UV-vis spectrometer analysis were measured to analyze the morphology and crystallinity and relationship between structure and PEC performance.

Development of polymorphic microsatellite loci in Odontobutis obscura using Illumina paired-end sequencing and the test of cross-species amplification

Odontobutis obscura is a bottom-dwelling freshwater fish native to East Asia. Its range encompasses southwest China, western Japan, and Geoje Island in South Korea. Despite its widespread range in China and Japan, only a small and spatially isolated population is found in South Korea. We developed a total of 23 novel and polymorphic microsatellite loci of O. obscura using Illumina paired-end shotgun sequencing and characterized them using 80 Japanese and Korean samples. An extensive genetic polymorphism was detected at these 23 loci, with the observed number of alleles at a locus ranging from 2 to 15 and expected and observed heterozygosities ranging from 0 to 0.656 and 0 to 0.547, respectively. Korean O. obscura exhibited a much lower level of genetic variability than the Japanese population did, probably as a result of long-term isolation combined with historical bottlenecks. The Japanese and Korean populations showed a high level of genetic differentiation with F_ST = 0.700 and R_ST = 0.913. Many of our primer sets were successfully transferable to congeneric O. interrupta and O. platycephala, which exhibited even greater polymorphism than Korean O. obscura. In conclusion, our study showed that these 23 microsatellite markers are useful for understanding the conservation biology and population genetic structure of O. obscura and other congeneric species.

Fabrication of a transparent conducting Ni-nanomesh-embedded film using template-assisted Ni electrodeposition and hot transfer process

We developed a new method for fabricating Ni nanomeshes for transparent conducting electrodes using template-assisted Ni electrodeposition and a hot transfer process.

Efficient optical activation of ion-implanted Zn acceptors in GaN by annealing under 10 kbar N2 overpressure

We continue our investigations into the optical activation of Zn-implanted GaN annealed under ever higher N2 overpressure. The samples studied were epitaxial GaN/sapphire layers of good optical quality which were implanted with a 1013 cm−2 dose of Zn+ ions at 200 keV, diced into equivalent pieces and annealed under 10 kbar of N2. The N2 overpressure permitted annealing at temperatures up to 1250°C for 1 hr without GaN decomposition. The blue Zn-related photoluminescence (PL) signal rises sharply with increasing anneal temperature. The Zn-related PL intensity in the implanted sample annealed at 1250°C exceeded that of the epitaxially doped GaN:Zn standard proving that high temperature annealing of GaN under kbar N2 overpressure can effectively remove implantation damage and efficiently activate implanted dopants in GaN. We propose a lateral LED device which could be fabricated using ion implanted dopants activated by high temperature annealing at high pressure.

Structural Defects in Heteroepitaxial and Homoepitaxial GaN

The microstructure and characteristic defects of heteroepitaxial GaN films grown on sapphire using molecular beam epitaxy (MBE) and metal-organic-chemical-vapor-deposition (MOCVD) methods and of homoepitaxial GaN grown on bulk substrates are described based on transmission electron microscopy (TEM), x-ray diffraction, and cathodoluminescence (CL) studies. The difference in arrangement of dislocations along grain boundaries and die influence of buffer layers on the quality of epitaxial films is described. The structural quality of GaN epilayers is compared to diat of bulk GaN crystals grown from dilute solution of atomic nitrogen in liquid gallium. The full width at half maximum (FWHM) of the x-ray rocking curves for these crystals was in the range of 20–30 arc sec, whereas for the heteroepitaxially grown GaN the FWHM was in the range of 5–20 arc min. Homoepitaxial MBE grown films had FWHMs of about 40 arc sec. The best film quality was obtained for homoepitaxial films grown using MOCVD; these samples were almost free from extended defects. For the bulk GaN crystals a substantial difference in crystal perfection was observed for the opposite sides of the plates shaped normal to the c direction. On one side the surface was almost atomically flat, and the underlying material was free of any extended structural defects, while the other side was rough, with a high density of planar defects. This difference was related to the polarity of the crystal. A large difference in crystal stoichiometry was also observed within different sublayers of the crystals. Based on convergent beam electron diffraction and cathodoluminescence, it is proposed that GaN antisite defects are related to the yellow luminescence observed in these crystals.

Doping, Activation of Impurities, and Defect Annihilation in Gan by High Pressure Annealing

GaN semiconductor is characterized by strong bonding and high vapor pressure of nitrogen. The strong bonds limit an efficiency of annealing procedures required for variety of semiconductor technologies, for example, post-implantation annealing, or doping by diffussion. Maximum temperatures employed up to now (at ambient pressure) in GaN annealing have not exceeded about 1100°C. A desired increase of annealing temperatures would cause a decomposition of GaN unless an elevated pressure of N2 is supplied. In this work, we report onapplication of high pressure annealing procedures (temperatures up to 1550°C and pressures up to 16 kbar) which enabled us to study variation of the properties of epitaxial films and bulk crystal of GaN. In particular, we discuss the following results obtained using high pressure annealing: i) structural quality improvement and increase of the thermal strain in as grown epitaxial layers of GaN/A12O3, The annealing at above 1300°C resulted in the decrease of the X-ray rocking curve width from about 700 arc sec. down to 470 arc sec., ii) drastic increase of bandedge (bound exciton) photoluminescence intensity iii) enhancement in removal of implant damage, iv) increase of diffusivity of Zn and Mg atoms (introduced by implantation and/or diffusion from external source). For Zn in epitaxial layers of GaN/A12O3 a diffusion starts at 1200–1250°C, v) enhancement of the blue-photoluminescence intensity in Zn and Mg implanted GaN. The performed experiments give an evidence of the importance of the defect (dislocations) in diffusion of Zn and Mg in the GaN semiconductor.

A processed HLA-A*24:02 pseudogene found in the peripheral blood of a father and his son

We encountered a case that exhibited a discrepancy in human leukocyte antigen-A (HLA-A) type determined by sequence-based typing (SBT) and sequence-specific primer (SSP) molecular typing. The child of this case was identified as A* 02:01 homozygote and A* 02, A* 24, respectively. The HLA-A type of his father was A* 02:01, 26:01, but low-resolution SSP also showed unexpected amplification with A* 24 primers as with the child. Serologic typing of the child and the father was A2/blank and A2/A26, respectively. Sequencing analysis of the A* 24 variant in the child and the father showed a complete deletion of all introns of the A* 24:02 allele. Though rare, this type of processed pseudogene variant can be one of the causes of discrepancies between high- and low-resolution HLA typing.

Microhomology-mediated deletion and gene conversion in African trypanosomes

Antigenic variation in African trypanosomes is induced by DNA double-strand breaks (DSBs). In these protozoan parasites, DSB repair (DSBR) is dominated by homologous recombination (HR) and microhomology-mediated end joining (MMEJ), while non-homologous end joining (NHEJ) has not been reported. To facilitate the analysis of chromosomal end-joining, we established a system whereby inter-allelic repair by HR is lethal due to loss of an essential gene. Analysis of intrachromosomal end joining in individual DSBR survivors exclusively revealed MMEJ-based deletions but no NHEJ. A survey of microhomologies typically revealed sequences of between 5 and 20 bp in length with several mismatches tolerated in longer stretches. Mean deletions were of 54 bp on the side closest to the break and 284 bp in total. Break proximity, microhomology length and GC-content all favored repair and the pattern of MMEJ described above was similar at several different loci across the genome. We also identified interchromosomal gene conversion involving HR and MMEJ at different ends of a duplicated sequence. While MMEJ-based deletions were RAD51-independent, one-sided MMEJ was RAD51 dependent. Thus, we describe the features of MMEJ in Trypanosoma brucei, which is analogous to micro single-strand annealing; and RAD51 dependent, one-sided MMEJ. We discuss the contribution of MMEJ pathways to genome evolution, subtelomere recombination and antigenic variation.

Effects of two-band superconductivity on the flux-line lattice in magnesium diboride

We present neutron scattering from the flux line lattice (FLL) in MgB2. Between 0.5 and 0.9 T the FLL undergoes a 30 degrees reorientation, and simultaneously the scattered intensity falls sharply consistent with the weaker superconducting pi band being suppressed with increasing field. We speculate that the pi and sigma bands favor different FLL orientations, and that the reorientation is driven by the suppression of the pi band. When the c axis of the crystal is rotated 45 degrees to the applied field the penetration depth anisotropy could be measured, and rises both as a function of applied field and temperature.

Phonon dispersion and lifetimes in MgB2

We measure phonon dispersion and linewidth in a single crystal of MgB2 along the Gamma-A, Gamma-M, and A-L directions using inelastic x-ray scattering. We use density functional theory to compute the effect of both electron-phonon coupling and anharmonicity on the linewidth, obtaining excellent agreement with experiment. Anomalous broadening of the E(2g) phonon mode is found all along Gamma-A. The dominant contribution to the linewidth is always the electron-phonon coupling.

Direct evidence for two-band superconductivity in MgB2 single crystals from directional point-contact spectroscopy in magnetic fields

We present the results of the first directional point-contact spectroscopy experiments in high-quality MgB2 single crystals. Because of the directionality of the current injection into the samples, the application of a magnetic field allowed us to separate the contributions of the sigma and pi bands to the total conductance of our point contacts. By using this technique, we were able to obtain the temperature dependency of each gap independent of the other. The consequent, strong reduction of the error on the value of the gap amplitude as a function of temperature allows a stricter test of the predictions of the two-band model for MgB2.

Vortex imaging in the pi band of magnesium diboride

We report scanning tunneling spectroscopy imaging of the vortex lattice in single crystalline MgB2. By tunneling parallel to the c axis, a single superconducting gap (Delta=2.2 meV) associated with the pi band is observed. The vortices in the pi band have a large core size compared to estimates based on H(c2) and show an absence of localized states in the core. Furthermore, superconductivity between the vortices is rapidly suppressed by an applied field. These results suggest that superconductivity in the pi band is, at least partially, induced by the intrinsically superconducting sigma band.

Magneto-optical study of the superconducting gap of MgB(2) single crystals

We present magneto-optical reflectivity results in the basal plane of the hexagonal MgB(2). The data were collected on a mosaic of MgB(2) single crystals with T(c)=38 K from the ultraviolet down to the far infrared as a function of temperature and magnetic field oriented along the c axis. In the far infrared, there is a clear signature of the superconducting gap with a gap ratio 2 Delta/k(B)T(c) approximately 1.2, well below the weak-coupling value. The gap is suppressed in an external magnetic field, which is a function of temperature. We extract the upper critical field H(c2) along the c axis. The temperature dependence of H(c2) is compatible with the Helfand-Werthamer behavior.

Temperature and field dependence of the anisotropy of MgB2

The anisotropy gamma of the superconducting state of high quality single crystals of MgB2 was determined, using torque magnetometry with two different methods. The anisotropy of the upper critical field was found to be temperature dependent, decreasing from gamma approximately 6 at 15 K to 2.8 at 35 K. Reversible torque data near T(c) reveal a field dependent anisotropy, increasing nearly linearly from gamma approximately equal to 2 in zero field to 3.7 in 10 kOe. The unusual temperature dependence is a true bulk property and can be explained by nonlocal effects of anisotropic pairing and/or the k--> dependence of the effective mass tensor.

Transmembrane domain-mediated colocalization of HLA-DM and HLA-DR is required for optimal HLA-DM catalytic activity

HLA-DM catalyzes peptide loading and exchange reactions by MHC class II molecules. Soluble recombinant DM, lacking transmembrane and cytoplasmic domains, was observed to have 200- to 400-fold less activity compared with the full-length protein in assays measuring DM-catalyzed peptide dissociation from purified HLA-DR1 in detergent solutions. Additional studies with truncated soluble DR1 demonstrated that transmembrane domains in DR1 molecules are also required for optimal activity. The potential requirement for specific interaction between the transmembrane domains of DM and DR was ruled out in experiments with chimeric DR1 molecules containing transmembrane domains from either DM or the unrelated protein CD80. These results suggested that the major role of the transmembrane domains is to facilitate colocalization of DM and DR in detergent micelles. The latter conclusion was further supported by the observation that HLA-DM-catalyzed peptide binding to certain murine class II proteins is increased by reducing the volume of detergent micelles. The importance of membrane colocalization was directly demonstrated in experiments in which DM and DR were reconstituted separately or together into membrane bilayers in unilamellar liposomes. Our findings demonstrate the importance of membrane anchoring in DM activity and underscore the potential importance of membrane localization in regulating peptide exchange by class II molecules.

The glyoxylate cycle in an arbuscular mycorrhizal fungus. Carbon flux and gene expression

The arbuscular mycorrhizal (AM) symbiosis is responsible for huge fluxes of photosynthetically fixed carbon from plants to the soil. Lipid, which is the dominant form of stored carbon in the fungal partner and which fuels spore germination, is made by the fungus within the root and is exported to the extraradical mycelium. We tested the hypothesis that the glyoxylate cycle is central to the flow of carbon in the AM symbiosis. The results of (13)C labeling of germinating spores and extraradical mycelium with (13)C(2)-acetate and (13)C(2)-glycerol and analysis by nuclear magnetic resonance spectroscopy indicate that there are very substantial fluxes through the glyoxylate cycle in the fungal partner. Full-length sequences obtained by polymerase chain reaction from a cDNA library from germinating spores of the AM fungus Glomus intraradices showed strong homology to gene sequences for isocitrate lyase and malate synthase from plants and other fungal species. Quantitative real-time polymerase chain reaction measurements show that these genes are expressed at significant levels during the symbiosis. Glyoxysome-like bodies were observed by electron microscopy in fungal structures where the glyoxylate cycle is expected to be active, which is consistent with the presence in both enzyme sequences of motifs associated with glyoxysomal targeting. We also identified among several hundred expressed sequence tags several enzymes of primary metabolism whose expression during spore germination is consistent with previous labeling studies and with fluxes into and out of the glyoxylate cycle.

The glyoxylate cycle in an arbuscular mycorrhizal fungus. Carbon flux and gene expression

The arbuscular mycorrhizal (AM) symbiosis is responsible for huge fluxes of photosynthetically fixed carbon from plants to the soil. Lipid, which is the dominant form of stored carbon in the fungal partner and which fuels spore germination, is made by the fungus within the root and is exported to the extraradical mycelium. We tested the hypothesis that the glyoxylate cycle is central to the flow of carbon in the AM symbiosis. The results of (13)C labeling of germinating spores and extraradical mycelium with (13)C(2)-acetate and (13)C(2)-glycerol and analysis by nuclear magnetic resonance spectroscopy indicate that there are very substantial fluxes through the glyoxylate cycle in the fungal partner. Full-length sequences obtained by polymerase chain reaction from a cDNA library from germinating spores of the AM fungus Glomus intraradices showed strong homology to gene sequences for isocitrate lyase and malate synthase from plants and other fungal species. Quantitative real-time polymerase chain reaction measurements show that these genes are expressed at significant levels during the symbiosis. Glyoxysome-like bodies were observed by electron microscopy in fungal structures where the glyoxylate cycle is expected to be active, which is consistent with the presence in both enzyme sequences of motifs associated with glyoxysomal targeting. We also identified among several hundred expressed sequence tags several enzymes of primary metabolism whose expression during spore germination is consistent with previous labeling studies and with fluxes into and out of the glyoxylate cycle.

Quantitative analysis of lymphocyte differentiation and proliferation in vitro using carboxyfluorescein diacetate succinimidyl ester

Mature T and B lymphocytes respond to receptor-delivered signals received during and following activation. These signals regulate the rates of cell death, growth, differentiation and migration that ultimately establish the behaviour patterns collectively referred to as immune regulation. We have been pursuing the philosophy that in vitro systems of lymphocyte stimulation, when analysed quantitatively, help reveal the logical attributes of lymphocyte behaviour. The development of carboxyfluorescein diacetate succinimidyl ester (CFSE) to track division has enabled the variable of division number to be incorporated into these quantitative analyses. Our studies with CFSE have established a fundamental link between differentiation and division number. Isotype switching, expression of T cell cytokines, surface receptor alterations and changes to intracellular signalling components all display independent patterns of change with division number. The stochastic aspects of these changes and the ability of external signals to independently regulate them argue for a probabilistic modelling framework for describing and understanding immune regulation.

Clinical study of orthokeratology in young myopic adolescents

This project was designed to study the efficacy of orthokeratology and its related problems in a population of young myopic adolescents. Fifty-four young myopia adolescents ages 11 to 15 years were enrolled in the study and followed over a 6-month period. The procedures included (1) baseline refraction, assessment of tear quality and quantity, and cornea examination including cornea topography, A-scan ultrasound of cornea thickness, and spectromicroscopy of the corneal endothelium; (2) diagnostic lens fitting and evaluation; (3) lens dispensing and educating the patients or their parents; (4) follow-up schedule and data analysis; and (5) maintenance lens dispensing and analysis of wearing schedules. Myopia was reduced between -1.25 and -5.00 D (-3.00 D average). Myopia reduction was almost complete in the first 6 months, with most of the reduction occurring during the first 2 weeks. Seventy-five percent of the possible reduction occurred during this 2-week time period. Tear quality and quantity influenced reduction speed and amount. Corneal thickness and endothelium remained unchanged over the study period. Subjective refraction is the most reliable method to measure the status of ocular refractive changes. Corneal staining occurred in 45% of subjects during the procedure, mainly in subjects with tear problems. Eighteen percent of the subjects showed induced astigmatism, which could be reversed by refitting the lens or changing the wearing schedule. Maintenance lenses had to be worn every night for young adolescents to maintain myopia reduction. Orthokeratology is a reliable option for reducing some myopia in young adolescents. The first 2 weeks are critical for the procedure. Complete examination and the data analysis procedures are important for monitoring prognosis and eye health.

Preparation of general proteinase substrates using 3,5-dinitrosalicylaldehyde

To search for new proteinases in Bacillus subtilis we have developed a general method for synthesizing chromogenic proteinase substrates using 3,5-dinitrosalicylaldehyde (DNSA). Hammersten casein and soluble protein from extracts from B. subtilis cells were labeled with DNSA in the presence of NaBH4. After dialysis (pH 7.8), the resultant 3,5-dinitro-2-hydroxybenzyl-casein (DNHB-casein) and DNHB-bacterial cell protein solutions were a light orange color. A model compound, N-benzyl-3,5-dinitro-2-hydroxybenzylamine was synthesized and estimated to have a molar absorption coefficient of 14,100 M-1 cm-1 at 366 nm at pH 8, which was used to calculate dye loading on casein. Chromogenic substrates prepared in this way should retain positive charges on lysine residues. DNHB-casein and DNHB-bacterial cell protein were incubated with varying concentrations of subtilisin BPN' for varying times, precipitated with trichloroacetic acid and centrifuged. The acid-soluble supernatant fractions were made basic with NaOH and absorbances were measured at 366 nm, the absorption maximum. Color production was proportional to subtilisin concentration and times of incubation; under the assay conditions used, the limit of detection of subtilisin was about 100 ng. Five proteinase activities were detected in soluble extracts of B. subtilis using DNHB-labeled proteins as substrates.