Rational synthesis of atomically thin quantum structures in nanowires based on nucleation processes.

Excitonic properties in quantum dot (QD) structure are essential properties for applications in quantum computing, cryptography, and photonics. Top-down fabrication and bottom-up growth by self-assembling for forming the QDs have shown their usefulness. These methods, however, still inherent issues in precision integrating the regimes with high reproducibility and positioning to realize the applications with on-demand quantum properties on Si platforms. Here, we report on a rational synthesis of embedding atomically thin InAs in nanowire materials on Si by selective-area regrowth. An extremely slow growth rate specified for the synthesis demonstrated to form smallest quantum structures reaching nuclear size, and provided good controllability for the excitonic states on Si platforms. The system exhibited sharp photoluminescence spectra originating from exciton and bi-exciton suggesting the carriers were confined inside the nuclei. The selective-area regrowth would open new approach to integrate the exciton states with Si platforms as building-blocks for versatile quantum systems.

Molecular Epidemiological Survey of Leptospira Infection of Wild Rodents in the Urban Settlement of Cambodia.

INTRODUCTION: Leptospirosis remains a major public health threat in Cambodia. In this study, we aimed at facilitating the development of preventive strategies against leptospirosis in Cambodia by conducting molecular epidemiological surveys of Leptospira infection among wild rodents. MATERIALS AND METHODS: One hundred sixty-three wild rodents were captured in the capital Phnom Penh and surrounding areas, and their kidneys and bladders were collected for analysis. Identification of wild rodent species was determined by using the cytochrome c oxidase I gene. TaqMan PCR of the flagellin B gene (flaB) was performed to detect Leptospira, and species of the isolates were identified by flaB sequencing analysis. RESULTS: The species and respective number of rodents collected were as follows: Rattus norvegicus, 80 (49.1%); Rattus argentiventer, 53 (32.5%); Rattus exulans, 6 (3.7%); Rattus indica, 15 (9.2%); Maxomys surifer, 3 (1.8%); and Rattus sp., 6 (3.7%). Leptospira was detected in 20 out of the 163 rodents (12.3%) and was categorized as either Leptospira interrogans or Leptospira noguchii. R. norvegicus had the highest prevalence of Leptospira (17.5%), and R. argentiventer and Rattus sp. showed infection rates of 9.4% and 16.7%, respectively. CONCLUSIONS: Based on these results, wild rodents living in urban areas of Cambodia were found to be important reservoirs of highly virulent Leptospira. The flaB sequence results of our study provided information regarding the prevalence of Leptospira species, which was dependent on the rodent species. This study is the first study on leptospirosis in wild rodents in the urban areas of Cambodia, where there is limited information on leptospirosis.

Growth of All-Wurtzite InP/AlInP Core-Multishell Nanowire Array.

We demonstrated the formation of all-wurtzite (WZ) InP/AlInP core-multishell (CMS) nanowires (NWs) by selective-area growth with the crystal structure transfer method. The CMS NWs consisting of an AlInP-based double heterostructure showed that the crystal structure of the multishell succeeded to the WZ phase from the WZ InP NW by the crystal structure transfer method. Transmission electron microscopy revealed that the core-shell interface had a few stacking faults due to lattice mismatch. In addition, lattice constants of WZ AlInP with a variation of Al content were determined by X-ray diffraction reciprocal space mappings, and the WZ AlInP shell had tensile strain along the c-axis. The WZ AlInP shells (Al content: 25-54%) showed cathode luminescence emissions at 1.6-2.1 eV, possibly related to In-rich domains due to composition fluctuation in the WZ AlInP shell.

Selective-Area Growth of InAs Nanowires on Ge and Vertical Transistor Application.

III-V compound semiconductor and Ge are promising channel materials for future low-power and high-performance integrated circuits. A heterogeneous integration of these materials on the same platform, however, raises serious problem owing to a huge mismatch of carrier mobility. We proposed direct integration of perfectly vertically aligned InAs nanowires on Ge as a method for new alternative integrated circuits and demonstrated a high-performance InAs nanowire-vertical surrounding-gate transistor. Virtually 100% yield of vertically aligned InAs nanowires was achieved by controlling the initial surface of Ge and high-quality InAs nanowires were obtained regardless of lattice mismatch (6.7%). The transistor performance showed significantly higher conductivity with good gate control compared to Si-based conventional field-effect transistors: the drain current was 0.65 mA/µm, and the transconductance was 2.2 mS/µm at drain-source voltage of 0.50 V. These demonstrations are a first step for building alternative integrated circuits using vertical III-V/multigate planar Ge FETs.

Age-Related Changes in Soluble Vascular Endothelial Growth Factor Receptor 1 (sVEGFR1) and Receptor 2 (sVEGFR2) in Healthy Japanese Subjects.

We measured serum soluble vascular endothelial growth factor receptor 1 (sVEGFR1) and receptor 2 (sVEGFR2) levels in healthy Japanese individuals in order to establish a reference value using a specific ELISA. Significant differences were observed in serum sVEGFR1 and sVEGFR2 levels between children and adults. To demonstrate the usefulness of the reference value for children, we measured serum sVEGFR1 and sVEGFR2 levels in children with diarrhea positive (D+) hemolytic uremic syndrome (HUS) as a preliminary study. Serum sVEGFR2 levels in children with HUS were markedly higher than those in healthy children from the onset of D + HUS. The reference value for healthy children in the present study will allow normal and pathological conditions to be discriminated from each other in future study.

Antibacterial effects of protruding and recessed shark skin micropatterned surfaces of polyacrylate plate with a shallow groove.

Antibacterial effects in terms of biofilm formation and swarming motility were studied using polyacrylate plates having protruding or recessed shark skin micropatterned surfaces with a shallow groove (2 µm pattern width and spacing, 0.4 µm pattern height). It was found that biofilm formation and swarming motility of Pseudomonas aeruginosa were strongly inhibited by the shark skin pattern plates with a shallow (0.4 µm) pattern height. Biofilm formation of Staphylococcus aureus was also strongly inhibited. Live bacteria were located on the pattern rather than in the spacing. When the shape of pattern was a linear ridge instead of shark skin, the antibacterial effects were weaker than seen with the shark skin pattern. The results indicate that the pattern of shark skin is important for decreasing bacterial infection even with a shallow feature height.

Leptospira-rat-human relationship in Luzon, Philippines.

Leptospirosis is a zoonotic infection that is caused by the pathogenic species of Leptospira. Rats are the most important reservoirs of these organisms. Our study aimed to characterize Leptospira isolates from humans and rats and elucidate the Leptospira-rat-human relationship in Luzon, Philippines. Forty strains were isolated from humans and rats. The isolates were confirmed to be Leptospira and pathogenic through rrl- and flaB-PCR, respectively. Around 73% of the isolates were found to be lethal to hamsters. Serotyping showed that there were mainly three predominant leptospiral serogroups in the study areas namely Pyrogenes, Bataviae, and Grippotyphosa. Gyrase B gene sequence analysis showed that all the isolates belonged to Leptospira interrogans. Most had 100% similarity with serovar Manilae (15/40), serovar Losbanos (8/40), and serogroup Grippotyphosa (8/40). Strains from each group had highly identical pulsed-field gel electrophoresis patterns and were further grouped as A (Pyrogenes, 14), B (Bataviae, 8), and C (Grippotyphosa, 10). Results further revealed that similar serotypes were isolated from both humans and rats in the same areas. It is suggested that these three predominant groups with highly similar intra-group PFGE patterns may have been primarily transmitted by rats and persistently caused leptospirosis in humans particularly in the Luzon islands.

Detection of Anaplasma phagocytophilum and Anaplasma bovis in small wild mammals from Taichung and Kinmen Island, Taiwan.

A total of 138 animals from 7 species (Apodemus agrarius, Bandicota indica, Crocidura suaveolens, Mus caroli, Mus formosanus, Rattus losea, and Suncus murinus) captured in Taichung, located in central Taiwan, and Kinmen Island, an island off the shore of China, were examined for the presence of Anaplasma phagocytophilum. The presence of the bacteria, which causes human granulocytic anaplasmosis, was examined by nested PCR targeting the16S rDNA. Twelve animals (8.7%) from M. caroli and R. losea, and 25 (18.1%) from A. agrarius, B. indica, M. caroli, and R. losea were infected with A. phagocytophilum and Anaplasma bovis, respectively. Phylogenetic analysis revealed that partial 16S rDNA sequences in the 12 aforementioned animals showed higher similarity to the sequences related to A. phagocytophilum detected in wild rodents (Rattus and Niviventer) from southeast China. The sequences of the other 25 animals belonged to the A. bovis clade. We demonstrated that small wild mammals were infected with A. phagocytophilum and A. bovis in Taichung and Kinmen Island, Taiwan.

PCR detection of Anaplasma phagocytophilum and Borrelia burgdorferi in Ixodes persulcatus ticks in Mongolia.

A molecular epidemiological survey was conducted to identify the tick-borne disease agents Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in Selenge Province, Mongolia. The survey was in response to a suspected A. phagocytophilum infection in a patient. In 2012, a total of 129 questing Ixodes persulcatus adult ticks were sampled by flagging vegetation. A. phagocytophilum and Borrelia spp. were detected by PCR, targeting the 16S rDNA (rrs) and 5S-23S intergenic spacer region, respectively. Infection rates for A. phagocytophilum and B. burgdorferi sensu lato spp. were 6.2% and 55.0%, respectively. Six of the 129 ticks (4.9%) were coinfected with A. phagocytophilum and B. burgdorferi sensu lato. Among Borrelia spp., the highest prevalence rate was that for B. garinii 20047 type (26.3%), followed by B. afzelii (7.8%) and B. garinii NT29 type (7.0%). Furthermore, ticks were detected that were dually infected with B. afzelii and B. garinii 20047 type (7.8%) and B. garinii NT29 and 20047 types (6.2%).

Sub 60 mV/decade switch using an InAs nanowire-Si heterojunction and turn-on voltage shift with a pulsed doping technique.

We report changes of turn-on voltage in InAs-Si heterojunction steep subthreshold-slope transistors by the Zn-pulsed doping technique for InAs nanowire channels. The doping of the nanowire channel moderately changes turn-on voltage from negative to positive voltage, while keeping a steep subthreshold-slope of 30 mV/decade under reverse bias direction. The formation of pseudointrinsic InAs segment is found to be important to make a normally off transistor with a steep subthreshold slope.

Van der Waals epitaxial double heterostructure: InAs/single-layer graphene/InAs.

Van der Waals (vdW) epitaxial double heterostructures have been fabricated by vdW epitaxy of InAs nanostructures on both sides of graphene. InAs nanostructures diametrically form on/underneath graphene exclusively along As-polar direction, indicating polarity inversion of the double heterostructures. First-principles and density functional calculations demonstrate how and why InAs easily form to be double heterostructures with polarity inversion.

Brazilian propolis ameliorates trinitrobenzene sulfonic acid-induced colitis in mice by inhibiting Th1 differentiation.

BACKGROUND: Propolis is a resinous substance collected by honeybees from leaf buds and cracks in the bark of various plants. We previously demonstrated the inhibitory activity of Brazilian propolis ethanolic extract against the differentiation process of Th17 cells and pathogenesis of collagen-induced arthritis, which is an experimental animal model of rheumatoid arthritis. Th1 cells are also involved in several autoimmune and inflammatory diseases, such as inflammatory bowel disease. In the present study, we demonstrated for the first time that Brazilian propolis significantly inhibited the generation of Th1 cells. Furthermore, we hypothesized that the administration of propolis to a murine model of colitis would suppress Th1 cell differentiation and ultimately ameliorate colitis. MATERIALS AND METHODS: CD4 T cells were stimulated under Th1-polarizing conditions (immobilized anti-CD3 and anti-CD28 antibodies with IL-12 plus an anti-IL-4 monoclonal antibody for 5days) with or without the propolis ethanolic extract. Cells were characterized for helper T cell subsets by flow cytometric analysis. Furthermore, we investigated the effects of propolis on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in a mouse model. RESULTS: Propolis dose-dependently reduced the frequency of IFNγ-producing CD4 T cells under Th1-polarizing conditions. Furthermore, the inhibitory effect of propolis on Th1 differentiation was demonstrated in vivo. The severity of colitis in mice fed propolis was significantly lower than that of mice fed the control diet. CONCLUSION: These findings suggest that the suppressive effect of Brazilian propolis on Th1 differentiation may be useful in controlling unbalanced cytokine networks in autoimmune diseases.

Development of immunochromatography-based methods for detection of leptospiral lipopolysaccharide antigen in urine.

Leptospirosis is an infectious disease caused by the spirochete bacteria Leptospira spp. and is commonly found throughout the world. Diagnosis of leptospirosis performed by culture and microscopic agglutination tests is laborious and time-consuming. Therefore, we aimed to develop a novel immunochromatography (ICG)-based method for detecting Leptospira antigen in the urine of patients and animals. We used the 1H6 monoclonal antibody (MAb), which is specific to the lipopolysaccharide (LPS) that is common among Leptospira spp. The MAb was coupled to 40-nm-diameter colloidal gold, and the amounts of labeled antibody and immobilized antibody were 23 µg and 2 µg per test, respectively. Several strains of Leptospira and other bacterial species were used to evaluate the sensitivities and specificities of the assays we developed. The detection limit of the assays was 10(6) cells/ml when disrupted whole bacterial cells were used. The assays were Leptospira specific since they did not cross-react with non-Leptospira bacteria used in the study. Application of diagnostic assays was done on the urine samples of 46 Leptospira-infected hamsters, 44 patients with suspected leptospirosis, and 14 healthy individuals. Pretreatment of the urine samples by boiling and centrifugation (for ultrafiltration and concentration) eliminated nonspecific reactions that occurred in the assay. The sensitivity and specificity of the ICG-based lateral flow assay (LFA) were 89% and 87%, respectively, which were higher than those of the dipstick assay, which were 80% and 74%, respectively. In summary, this ICG-based LFA can be used as an alternative diagnostic assay for leptospirosis. Further development is still necessary to improve the assay.

GaAs nanowire growth on polycrystalline silicon thin films using selective-area MOVPE.

The growth mechanism of GaAs nanowires (NWs) grown on polycrystalline silicon (poly-Si) thin films using selective-area metalorganic vapor-phase epitaxy was investigated. Wire structures were selectively grown in the mask openings on a poly-Si substrate. The appearance ratio of wire structures strongly depended on the growth conditions and deposition temperature of the poly-Si substrate. Evaluation of the grown shapes and growth characteristics revealed that GaAs NWs grown on a poly-Si substrate have the same growth mechanism as conventional GaAs NWs grown on a single-crystalline GaAs or Si substrate. Experiments showed that the wire structure yield can be improved by increasing the Si grain size and/or increasing the Si deposition temperature. The growth model proposed for understanding NW growth on poly-Si is based on the mask opening size, the Si grain size, and the growth conditions. The ability to control the growth mode is promising for the formation of NWs with complex structures on poly-Si thin layers.

Astasia and pyrexia related to Borrelia garinii infection in two dogs in Hokkaido, Japan.

Two dogs that exhibited sudden astasia, anorexia and fever higher than 40°C were suspected of having Lyme disease in July 2011. Clinical symptoms gradually improved with antibiotic treatment in both cases. Polymerase chain reaction and sequence analysis revealed Borrelia garinii DNA fragments in the peripheral blood in the acute disease phase. Serological tests, including enzyme linked immunosorbent assay and Western blot analysis, showed an increased IgG antibody titer against Borrelia pathogens in one of the dogs. These findings suggested that diagnosis of the two dogs was Lyme disease related to B. garinii infection.

Survey on tick-borne pathogens in thoroughbred horses in the Hidaka district, Hokkaido, Japan.

A total of 87 Thoroughbred horses and 10 ixodid ticks from a ranch in Hidaka district, Hokkaido were tested for tick-borne diseases. Using the indirect fluorescent antibody (IFA) method, 3.4, 92.0 and 97.7% of the horses showed antibody titers of ≥ 80 against Anaplasma phagocytophilum, Rickettsia helvetica, and Borrelia garinii, respectively. This is the first report of infection with the 3 pathogens in horses in Japan. Using PCR, DNAs from the peripheral blood of all horses were found negative with any Anaplasma, Rickettsia and Borrelia spp., while those from Haemaphysalis megaspinosa ticks were found positive for Anaplasma sp. closely related to A. phagocytophilum in Japan, and A. bovis. B. japonica was also detected in an H. flava tick for the first time.

A III-V nanowire channel on silicon for high-performance vertical transistors.

Silicon transistors are expected to have new gate architectures, channel materials and switching mechanisms in ten years' time. The trend in transistor scaling has already led to a change in gate structure from two dimensions to three, used in fin field-effect transistors, to avoid problems inherent in miniaturization such as high off-state leakage current and the short-channel effect. At present, planar and fin architectures using III-V materials, specifically InGaAs, are being explored as alternative fast channels on silicon because of their high electron mobility and high-quality interface with gate dielectrics. The idea of surrounding-gate transistors, in which the gate is wrapped around a nanowire channel to provide the best possible electrostatic gate control, using InGaAs channels on silicon, however, has been less well investigated because of difficulties in integrating free-standing InGaAs nanostructures on silicon. Here we report the position-controlled growth of vertical InGaAs nanowires on silicon without any buffering technique and demonstrate surrounding-gate transistors using InGaAs nanowires and InGaAs/InP/InAlAs/InGaAs core-multishell nanowires as channels. Surrounding-gate transistors using core-multishell nanowire channels with a six-sided, high-electron-mobility transistor structure greatly enhance the on-state current and transconductance while keeping good gate controllability. These devices provide a route to making vertically oriented transistors for the next generation of field-effect transistors and may be useful as building blocks for wireless networks on silicon platforms.

Bidirectional growth of indium phosphide nanowires.

We present a bidirectional growth mode of InP nanowires grown by selective-area metalorganic vapor-phase epitaxy (SA-MOVPE). We studied the effect of the supply ratio of DEZn ([DEZn]) on InP grown structure morphology and crystal structures during the SA-MOVPE. Two growth regimes were observed in the investigated range of the [DEZn] on an InP(111)B substrate. At low [DEZn], grown structures formed tripod structures featuring three nanowires branched toward the [111]A directions. At high [DEZn], we obtained hexagonal pillar-type structures vertically grown on the (111)B substrate. These results show that the growth direction changes from [111]A to [111]B as [DEZn] is increased. We propose a growth mechanism based on the correlation between the incident facet of rotational twins and the shapes of the grown structures. Our results bring us one step closer to controlling the direction of nanowires on a Si substrate that has a nonpolar nature. They can also be applied to the development of InP nanowire devices.

Position-controlled III-V compound semiconductor nanowire solar cells by selective-area metal-organic vapor phase epitaxy.

We demonstrate position-controlled III-V semiconductor nanowires (NWs) by using selective-area metal-organic vapor phase epitaxy and their application to solar cells. Efficiency of 4.23% is achieved for InP core-shell NW solar cells. We form a 'flexible NW array' without a substrate, which has the advantage of saving natural resources over conventional thin film photovoltaic devices. Four junction NW solar cells with over 50% efficiency are proposed and discussed.

van der Waals epitaxy of InAs nanowires vertically aligned on single-layer graphene.

Semiconductor nanowire arrays integrated vertically on graphene films offer significant advantages for many sophisticated device applications. We report on van der Waals (VDW) epitaxy of InAs nanowires vertically aligned on graphene substrates using metal-organic chemical vapor deposition. The strong correlation between the growth direction of InAs nanowires and surface roughness of graphene substrates was investigated using various graphene films with different numbers of stacked layers. Notably, vertically well-aligned InAs nanowire arrays were obtained easily on single-layer graphene substrates with sufficiently strong VDW attraction. This study presents a considerable advance toward the VDW heteroepitaxy of inorganic nanostructures on chemical vapor-deposited large-area graphenes. More importantly, this work demonstrates the thinnest epitaxial substrate material that yields vertical nanowire arrays by the VDW epitaxy method.