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This study aims to create controlled fine space by electrospinning, and to develop the electrode materials for high-performance energy devices. With the popularization of mobile devices, household appliances, hybrid vehicles, electric vehicles, and the like, the use of power storage devices is expanding, and further performance improvements are required. In this study, a novel electrode material was developed by compositing Si with carbon nanofibers derived from polyacrylonitrile (PAN) by electrospinning and heat treatment. The texture and structure of the nanofibers were observed and analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and transmission electron microscopy (TEM) combined with image processing. Nano spaces were created in the CNFs and Si particles were able to be contained in the CNFs. In the second and subsequent cycles of the charge/discharge experiments of lithium ion battery (LIB) electrode made from the materials, the capacity was more than twice the theoretical capacity using graphite, and good cycle performance was obtained.
In recent years, the discovery of massive quasars at
has provided a striking challenge to our understanding of the origin and growth of supermassive black holes in the early Universe. Mounting observational and theoretical evidence indicates the viability of massive seeds, formed by the collapse of supermassive stars, as a progenitor model for such early, massive accreting black holes. Although considerable progress has been made in our theoretical understanding, many questions remain regarding how (and how often) such objects may form, how they live and die, and how next generation observatories may yield new insight into the origin of these primordial titans. This review focusses on our present understanding of this remarkable formation scenario, based on the discussions held at the Monash Prato Centre from November 20 to 24, 2017, during the workshop ‘Titans of the Early Universe: The Origin of the First Supermassive Black Holes’.
The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.
Surface radiocarbon (Δ14C) in the North Pacific has been monitored using a commercial volunteer observation ship since the early 2000s. Here we report the temporal and spatial variations in Δ14C in the summer surface water when the surface ocean is vertically stratified over a 13-yr period, 2004–2016. The long-term Δ14C decreasing trend after the late 1970s in the subtropical region has continued to the present and the rate of decrease of the Kuroshio and Kuroshio Extension, North Pacific and California current areas is calculated to be –3.3, –5.2 and –3.3 ‰/yr, respectively. After 2012 the Δ14C of the Kuroshio and Kuroshio Extension area, however, has remained at an approximately constant value of around 50‰. The result may indicate that subtropical surface Δ14C in the western North Pacific has reached an equilibrium with atmospheric Δ14CO2. The Δ14C in the subarctic region is markedly lower than values in the subtropical region and it seems that the decreasing tendency of surface Δ14C has changed to an increasing tendency after 2010. The results may indicate that bomb-produced 14C, which has accumulated below the mixed layer in the past few decades, has been entrained into the surface layer by deep convection.
This study focused on parotid gland tumours diagnosed as benign by fine-needle aspiration cytology and investigated the necessity of frozen section biopsy.
There were 104 cases of parotid gland tumour where fine-needle aspiration cytology was benign and frozen section biopsy was subsequently performed, between April 2006 and June 2016. In this retrospective study, the results of frozen section biopsy were analysed and compared with the final histological diagnosis.
Among the 104 cases diagnosed as benign by fine-needle aspiration cytology, 102 cases and 2 cases were diagnosed as benign and malignant, respectively, by frozen section biopsy. The final histological diagnoses showed that 98 cases were benign and 6 cases were malignant. The sensitivity and specificity values of frozen section biopsy in detecting malignant tumours were 33 per cent and 100 per cent, respectively.
The necessity of frozen section biopsy in cases with benign fine-needle aspiration cytology may be low in parotid gland surgery.
Between July of 2012 and December of 2014, 39 patients were enrolled prospectively to investigate the prevalence of glucose transporter 1 (GLUT1) deficiency in a ketogenic diet clinic. None of them had GLUT1 deficiency. All patients seen in the same clinic within the same period were reviewed retrospectively. A total of 18 of these 85 patients had a genetic diagnosis, including GLUT1 deficiency, pathogenic copy number variants, congenital disorder of glycosylation, neuronal ceroid lipofuscinosis type II, mitochondrial disorders, tuberous sclerosis, lissencephaly, and SCN1A-, SCN8A-, and STXBP1-associated epileptic encephalopathies. The prevalence of genetic diagnoses was 21% and prevalence of GLUT1 deficiency was 2.4% in our retrospective cohort study.
Employing a comparative experimental design drawing on over 18,000 interviews across eleven countries on four continents, this article revisits the discussion about the economic and cultural drivers of attitudes towards immigrants in advanced democracies. Experiments manipulate the occupational status, skin tone and national origin of immigrants in short vignettes. The results are most consistent with a Sociotropic Economic Threat thesis: In all countries, higher-skilled immigrants are preferred to their lower-skilled counterparts at all levels of native socio-economic status (SES). There is little support for the Labor Market Competition hypothesis, since respondents are not more opposed to immigrants in their own SES stratum. While skin tone itself has little effect in any country, immigrants from Muslim-majority countries do elicit significantly lower levels of support, and racial animus remains a powerful force.
The purpose of this study was to clarify the association between hand, foot, and mouth disease (HFMD) epidemics and meteorological conditions. We used HFMD surveillance data of all 47 prefectures in Japan from January 2000 to December 2015. Spectral analysis was performed using the maximum entropy method (MEM) for temperature-, relative humidity-, and total rainfall-dependent incidence data. Using MEM-estimated periods, long-term oscillatory trends were calculated using the least squares fitting (LSF) method. The temperature and relative humidity thresholds of HFMD data were estimated from the LSF curves. The average temperature data indicated a lower threshold at 12 °C and a higher threshold at 30 °C for risk of HFMD infection. Maximum and minimum temperature data indicated a lower threshold at 6 °C and a higher threshold at 35 °C, suggesting a need for HFMD control measures at temperatures between 6 and 35 °C. Based on our findings, we recommend the use of maximum and minimum temperatures rather than the average temperature, to estimate the temperature threshold of HFMD infections. The results obtained might aid in the prediction of epidemics and preparation for the effect of climatic changes on HFMD epidemiology.
We report on the formation of shallow junctions with high activation in both n+/p and p+/n Ge junctions using ion implantation and Flash Lamp Annealing (FLA). The shallowest junction depths (Xj) formed for the n+/p and p+/n junctions were 7.6 nm and 6.1 nm with sheet resistances (Rs) of 860 ohms/sq. and 704 ohms/sq., respectively. By reducing knocked-on oxygen during ion implantation in the n+/p junctions, Rs was decreased by between 5% and 15%. The lowest Rs observed was 235 ohms/sq. with a junction depth of 21.5 nm. Hall measurements clearly revealed that knocked-on oxygen degraded phosphorus activation (carrier concentration). In the p+/n Ge junctions, we show that ion implantation damage induced high boron activation. Using this technique, Rs can be reduced from 475 ohms/sq. to 349 ohms/sq. These results indicate that the potential for forming ultra-shallow n+/p and p+/n junctions in the nanometer range in Ge devices using FLA is very high, leading to realistic monolithically-integrated Ge CMOS devices that can take us beyond Si technology.
Background: The ketogenic diet (KD) is used to treat severe childhood-onset epileptic encephalopathies, such as Infantile Spasms (IS). Unfortunately, limited resources for KD initiation result in treatment delays. We ask if earlier KD treatment of early-onset drug-resistant epilepsy results in better seizure outcomes. Methods: Children who started KD before age 4 years between 2000-present at SickKids Hospital were identified. Six-month seizure outcome was calculated as percent of pre-diet baseline seizure frequency (BSF). Results: 67 children were identified. 30 (44.8%) started KD <2 years old, 37 (55.2%) started KD 2-4 years old. Among <2 years old group, 83.3% achieved 50% reduction in BSF and 36.7% achieved 90% reduction. Among 2-4 year old group, 62.2% achieved 50% reduction in BSF and 24.3% achieved 90% reduction. 38 children had a history of IS; 17 with IS at diet initiation and 21 with past history of IS. 41.2% of the spasms cohort achieved 90% reduction in BSF, compared to 23.8% of the post-spasms cohort. Conclusions: KD was more effective when started before age 2 years than 2-4 years, and more effective in children with IS than in children with past history of IS. A rapid protocol for KD initiation in young infants and children may improve long-term outcomes
We investigate clustering properties of quasars using a new version of our semi-analytic model of galaxy and quasar formation with state-of-the-art cosmological N-body simulations (Ishiyama et al. 2015; Oogi et al. 2015). We assume that a major merger of galaxies triggers quasar activity. We find that the quasar bias does not depend significantly on the quasar luminosity, similar to observed trends. This result reflects the fact that quasars with a fixed luminosity have various Eddington ratios and thus have various host halo masses that primarily determine the quasar bias. The quasar bias increases with redshift, which is in qualitative agreement with observations. Our bias value is lower than the observed values at high redshifts, implying that we need some mechanisms that make quasars inactive in low-mass haloes and/or that make them more active in high-mass haloes.
In our cosmological, chemodynamical simulations, (i) the black hole mass–velocity dispersion relation does not evolve, and black holes actually grow along the relation. (ii) the stellar mass–metallicity relation does not change its shape, while the gas-phase relation has a steeper slope at higher redshifts. (iii) While stellar metallicity gradients are made shallower by galaxy mergers, gas-phase gradients are affected more strongly by AGN feedback.
Four microseconds long Ar3+ beam with injection energy of 15 keV/u has been injected into the Digital Accelerator of the High-Energy Accelerator Research Organization. Beam production, transportation, and injection are described as well as machine properties. Results of a free running experiment under static magnetic field and longitudinal confinement and acceleration under a fast ramping magnetic field are presented in detail with a brief discussion on the beam lifetime.
Periodically arrayed rows of fine Fe2Hf Laves phase particles were found to form in 9Cr ferritic steel. Microstructural observation demonstrates that the particles were formed on cooling through the interphase precipitation on the phase transformation from the δ ferrite to the γ austenite along the eutectoid transformation route of δ → γ+Fe2Hf and subsequently a phase transformation from the austenite to the α ferrite took place. This eutectoid route is expected to be effectively used for improving the long term creep strength of ferritic steels with Laves phase.
Chalcogenide materials have regained attention after the recent recognition of the compatibility of transition metal dichalcogenides with graphene. Additionally, there has been a recent appreciation for the rich variety of properties they support due to the anomalies in the materials’ intrinsic band structure. These materials generally have layered structures and weak interlayer connection through the chalcogen layer and its van der Waals type bonding. We have synthesized orthorhombic copper telluride and measured its electrical transport properties. The results of these measurements reveal that the conduction is metallic in both the in-plane and out-of-plane directions. The range of stability of this structure is examined along with the lattice constants. The independence of the resistivity in samples to changes in excess copper indicates that the transport is essentially within the conducting planes. This result shows that the material hosts two-dimensional character likely due to its covalent interlayer bonding.
We present a concept to increase efficiencies utilizing nonlinear elements integrated with our semiconductor nanowire networks. Demonstrated here is power generation with thermoelectric devices made of two nanowire networks, one silicon and one indium phosphide, grown on a mechanically flexible copper substrate. Electron microscopy was utilized to characterize structural integrity of the nanowire networks. Non-linear current-voltage characteristics were observed, which suggests a new platform to increase maximum electrical power generation for a given temperature gradient.
Preparation of a sigma-CrFe single-phase specimen was achieved by arc melting of pure Fe and Cr, cold rolling, and subsequent annealing at 973 K or 1073 K in vacuum. Cold rolling before annealing is effective for the annealing-induced formation of sigma-CrFe from the bcc solid-solution phase. The phase stability and the structural change from sigma-CrFe to a bcc solid-solution phase under fast electron irradiation were investigated by in situ transmission electron microscope (TEM) observation in the temperature range between 22 K and 473 K by using an ultra-high voltage electron microscope (UHVEM). The phase transition of sigma-CrFe by fast electron irradiation was found to occur at a particular temperature.
The liver fluke, Opisthorchis viverrini, and the minute intestinal fluke, Haplorchis taichui, are prevalent in many Asian countries. This study analysed the patterns of infections of O. viverrini and H. taichui in Lahanam and Thakhamlien villages (Savannakhet Province, Lao PDR), in two cross-sectional investigations. Out of a total of 207 human participants, post-anthelmintic treatment positivity rates for expelled worms were 170 (82.1%) for H. taichui and 65 (31.4%) for O. viverrini. Both these species co-exist in the study villages. When each parasite was analysed separately, H. taichui infections reached a plateau among people aged >20 years. Opisthorchis viverrini infection rates were highest in the age group 21–30 years, with decreasing infection rates after the age of 30. Our findings indicated that fish-borne trematode infections were more prevalent among adults. Fish, common intermediate hosts, were acquired in the study area for analysis. The examination of 35 species of fish as intermediate hosts found O. viverrini metacercariae in only six species, and these were found mostly during the month of November. Many farmers who live on the rice fields obtain their food from their immediate environment, including these intermediate-host fish, potentially putting them at greater risk of O. viverrini infection. By contrast, H. taichui metacercariae were found in three species of fish obtained from the market, meaning that anyone could consume them and become infected. If people who work in rice fields limit the species of fish they consume, or avoid consuming raw fish during the month of November, they may reduce their risk of O. viverrini infection.
More than 50% of total input energy is wasted as heat in various industrial processes. If we could harness a small fraction of the waste heat while satisfying the economic demands of cost versus performance, then thermoelectric (TE) power generation could bring substantial positive impacts. To meet these demands single-crystal semiconductor nanowire networks have been investigated as a method to achieve advanced TE devices because of their predicted large reduction in thermal conductivity and increase in power factor.
To further our goal of developing practical and economical TE devices, we designed and developed a material platform that combined a semiconductor nanowire network and a semiconductor thin film integrated directly on a mechanically flexible metallic substrate. We assessed the potential of this platform by using indium phosphide (InP) nanowire networks and a doped poly-silicon (poly-Si) thin film combined on copper sheets. InP nanowires were grown by metal organic chemical vapor deposition (MOCVD). In the nanowire network, InP nanowires were grown in three-dimensional networks in which electrical charges and heat travel under the influence of their characteristic scattering mechanisms over a distance much longer than the mean length of the constituent nanowires. Subsequently, plasma-assisted CVD was utilized to form a poly-Si thin film to prevent electrical shorting when an ohmic copper top contact was made. An additional facet to this design is the utilization of multiple materials to address the various temperature ranges at which each material is most efficient at heat-to-energy conversion. The utilization of multiple materials could enable the enhancement of total power generation for a given temperature gradient. We investigated the use of poly-Si thin films combined with InP nanowires to enhance TE properties. TE power production and challenges of a large area nanowire device on a flexible metallic substrate were presented.
Multi-functionalization of catalytically-active nanomaterials provides a valuable tool for enhancing reaction yield by shifting reaction equilibrium, and potentially also by adjusting reaction-diffusion kinetics. For example, multi-functionalization of mesoporous silica to make the interior pore surface hydrophobic can enhance yield in dehydration reactions. Detailed molecular-level modeling to describe the pore environment, as well as the reaction and diffusion kinetics is challenging, although we briefly discuss current strategies. Our focus, however, is on coarse-grained stochastic modeling of the overall catalytic process for highly restricted transport within narrow pores (with single-file diffusion), while accounting for a tunable interaction of the pore interior with reaction products. We show that making the pore interior unfavorable to products can significantly enhance yield due to both thermodynamic and kinetics factors.