Sophia University
UniversityTokyo, Japan
Research output, citation impact, and the most-cited recent papers from Sophia University (Japan). Aggregated across the NobleBlocks index of 300M+ scholarly works.
Top-cited papers from Sophia University
In this review we will explore recent advances in the design and application of excited-state intramolecular proton-transfer (ESIPT) based fluorescent probes. Fluorescence based sensors and imaging agents (probes) are important in biology, physiology, pharmacology, and environmental science for the selective detection of biologically and/or environmentally important species. The development of ESIPT-based fluorescence probes is particularly attractive due to their unique properties, which include a large Stokes shift, environmental sensitivity and potential for ratiometric sensing.
The effect of the sample particle size on the crystal structure and the Curie temperature of BaTiO 3 powder has been investigated in the particle size range 0.1 to 1.0 μm. The transformation from tetragonal to cubic symmetry occurs at a critical particle size of 0.12 μm at room temperature, and the Curie temperature drops below room temperature at the critical particle size.
Transparent superhydrophobic thin films with TiO2 photocatalyst were prepared by utilizing a sublimation material and subsequent coating of a (fluoroalkyl)silane. The transparency of the films decreased with increasing TiO2 concentration, which was attributed to the size difference of the starting materials. The film with only 2 wt % TiO2 maintained higher contact angle than the film without TiO2 after 1800-h outdoor exposure, the accumulation of stain being avoided due to TiO2 photocatalysis. The films prepared in this study are the first ones that satisfy the requirements of transparency, superhydrophobicity, and long lifetime simultaneously.
A stable glow plasma at atmospheric pressure has been achieved for plasma treatment under selected conditions, for example the structure of electrodes, the kind of dilute gas, and the frequency of power. The surface fluorination of PET film and carbon thin-film deposition by such a plasma is described here. The surface energy can be controlled by plasma treatment of various concentrations (O2/CF4/He) in the same way as the lower pressure method that has been reported by Kogoma and co-workers (1987). Active species in plasma are identified by emission spectroscopy.
The static mechanical properties of major branches of the human arteries (common carotid artery, abdominal aorta, femoral artery, and brachial artery) were studied in 39 subjects, aged 6-81 years, using an ultrasonic phase locked echo tracking system that allows continuous transcutaneous measurement of the diameter of the artery. The stiffness indices were calculated from the relation between systemic blood pressure and arterial diameter. With advancing age there was a significant increase in the diameter of all arteries with a reduction in percentage change in diameter. The stiffness index increased with age in all arteries; however, in the brachial and femoral arteries there was considerable variation in the individual values for a given age. The age associated increase in stiffness was statistically significant only in the common carotid artery and the abdominal aorta. Although the mechanical properties of the peripheral arteries were significantly influenced by the measuring environment, the calculated stiffness indices were less vulnerable to these stimuli in the central arteries. These results indicate that the stiffness indices of the peripheral muscular arteries are modified appreciably by vasoactive stimuli and that the mechanical properties of the deeper elastic arteries provide sufficiently reliable information about changes caused by aging and arteriosclerosis. The new ultrasonic method used appears to be suitable for this analysis.
ROS, calcium, and electric signals mediate rapid systemic signaling in plants.
Multiple photovoltaic (PV) modules feeding a common load is the most common form of power distribution used in solar PV systems. In such systems, providing individual maximum power point tracking (MPPT) schemes for each of the PV modules increases the cost. Furthermore, its v-i characteristic exhibits multiple local maximum power points (MPPs) during partial shading, making it difficult to find the global MPP using conventional single-stage (CSS) tracking. To overcome this difficulty, the authors propose a novel MPPT algorithm by introducing a particle swarm optimization (PSO) technique. The proposed algorithm uses only one pair of sensors to control multiple PV arrays, thereby resulting in lower cost, higher overall efficiency, and simplicity with respect to its implementation. The validity of the proposed algorithm is demonstrated through experimental studies. In addition, a detailed performance comparison with conventional fixed voltage, hill climbing, and Fibonacci search MPPT schemes are presented. Algorithm robustness was verified for several complicated partial shading conditions, and in all cases this method took about 2 s to find the global MPP.
SYNOPSIS. A study of common snapping turtles conducted from 1975 through 1992 in southeastern Michigan provided sufficient demographic data to examine how life history characteristics may constrain population responses of long-lived organisms. Females reached sexual maturity between 11 and 16 years of age. Minimum reproductive frequency was less than annual (0.85), and nest survivorship over 17 years ranged from 0 to 64% and averaged 23%. Survivorship of yearlings had to be estimated since hatchlings can pass through the mesh on traps. Actual survivorship of juveniles was over 0.65 by age 2 and averaged 0.77 between the ages of 2 and 12 years. Annual survivorship of adult females ranged from 0.88 to 0.97. A life table for the population resulted in a cohort generation time of 25 years. Population stability was most sensitive to changes in adult or juvenile survival, and less sensitive to changes in age at sexual maturity, nest survival or fecundity. An increase in annual mortality of 0.1 on adults over 15 years of age with no density-dependent compensation would halve the number of adults in less than 20 years. The results from the present study indicate that life history traits of long-lived organisms consist of co-evolved traits that severely constrain the ability of populations to respond to chronic disturbances. Successful management and conservation programs for long-lived organisms will be those that recognize that protection of all life stages is necessary. Without protection of adults and older juveniles, programs that protect nests and headstart hatchlings have a low probability of success. Carefully managed sport harvests of turtles or other long-lived organisms may be sustainable; however, commercial harvests will certainly cause substantial population declines
This study investigates the potentially facilitative effects of internal and external attention-drawing devices—output and visual input enhancement—on the acquisition of English relativization by adult English as a second language (ESL) learners. Specifically, the study addresses: (a) whether the act of producing output promotes noticing of formal elements in the target language (TL) input and affects subsequent learning of the form; and (b) whether such output- induced noticing and learning, if any, would be the same as that effected by visual input enhancement designed to draw learners' attention to problematic form features in the input. These questions were examined in a controlled experimental study in which the requirements of output and exposure to enhanced input were systematically varied. A computer-assisted reconstruction and reading task was used as the vehicle of presentation of the target input materials. The major findings are: (a) Those engaged in output-input activities outperformed those exposed to the same input for the sole purpose of comprehension in learning gains; (b) those who received visual input enhancement failed to show measurable gains in learning, despite the documented positive impact of enhancement on the noticing of the target form items in the input; and (c) in view of the above, no support was found for the hypothesis that the effect of input enhancement was comparable to that of output. The subsequent discussion centers on reexamining the construct of noticing and argues for the need to consider levels and types of processing in order to account for how sensory detection can lead to learning.
Unusual glow discharges in air, argon, oxygen and nitrogen at atmospheric pressure can be produced using a 50 Hz source. This technique is introduced on the basis of the idea of a lower dielectric breakdown voltage gas. The electrode system, which is composed of a fine metal wire mesh of specified radius and a dielectric substance, is very useful for plasma surface processes and for chemical reactions in the plasma bulk. The observations of the Lissajous figure of voltage-electric charges and of the current pulse shapes are proposed as a method of distinguishing between the atmospheric pressure glow plasma and the silent electric discharge.
Abiotic stresses such as drought, heat or salinity are a major cause of yield loss worldwide. Recent studies revealed that the acclimation of plants to a combination of different environmental stresses is unique and cannot be directly deduced from studying the response of plants to each of the different stresses applied individually. Here we report on the response of Arabidopsis thaliana to a combination of salt and heat stress using transcriptome analysis, physiological measurements and mutants deficient in abscisic acid, salicylic acid, jasmonic acid or ethylene signaling. Arabidopsis plants were found to be more susceptible to a combination of salt and heat stress compared to each of the different stresses applied individually. The stress combination resulted in a higher ratio of Na+/K+ in leaves and caused the enhanced expression of 699 transcripts unique to the stress combination. Interestingly, many of the transcripts that specifically accumulated in plants in response to the salt and heat stress combination were associated with the plant hormone abscisic acid. In accordance with this finding, mutants deficient in abscisic acid metabolism and signaling were found to be more susceptible to a combination of salt and heat stress than wild type plants. Our study highlights the important role abscisic acid plays in the acclimation of plants to a combination of two different abiotic stresses.
A novel technology for controlling the In composition of InGaN quantum wells on the same wafer was developed, which paved the way for the monolithic integration of three-primary-color nano-light-emitting diodes. In the experiment, InGaN/GaN multiple quantum well nanocolumn arrays with nanocolumn diameters from 137 to 270 nm were prepared on the same substrate with the Ti-mask selective area growth by rf-plasma-assisted molecular beam epitaxy. The emission color changed from blue to red (from 479 to 632 nm in wavelength) with increasing nanocolumn diameter. The emission color change mechanism was clearly explained by the beam shadow effect of the neighboring nanocolumns.
Demography provides critical data to increase our understanding of the evolution, ecology, and conservation of primate populations. The chimpanzees of the Mahale Mountains National Park, Tanzania, have been studied for more than 34 yr on the basis of individual identification and standardized attendance records. From this long-term study, we derived the following demographic data: The major cause of death was disease (48%), followed by senescence (24%) and within-species aggression (16%). Fifty percent of Mahale chimpanzees died before weaning. The median ages of female life history variables were: first maximal swelling, 10.0 yr (n = 5); emigration, 11.0 yr (n = 11); and first birth, 13.1 yr (n = 5). The median period of adolescent infertility was 2.8 yr (n = 4) when calculated from the age at immigration to that at first birth. Female fecundity was highest between 20 and 35 yr of age, with an annual birth rate of 0.2. Twenty-six females that were observed from a young age (10-13 yr) to death at various ages (15-40 yr) gave birth to an average of 3.9 and weaned an average of 1.4 offspring. Twenty-five females that were observed from middle age (18-33 yr) to death in older age (31-48) gave birth to an average of 2.7 and weaned an average of 2.0 offspring. The post-reproductive lifespan for female chimpanzees was defined as the number of years that passed from the year when the last offspring was born to the year when the female died, minus 5. Twenty-five percent of old females had a post-reproductive lifespan. The interbirth interval after the birth of a son (x = 72 mo) tended to be longer than that after the birth of a daughter (x = 66 mo). The extent of female transfer, which is a rule in chimpanzees, is influenced by the size and composition of the unit group and size of the overall local community.
For large photovoltaic power generation plants, number of panels are interconnected in series and parallel to form a photovoltaic (PV) array. In this configuration, partial shade will result in decrease in power output and introduce multiple peaks in the P-V curve. As a consequence, the modules in the array will deliver different row currents. Therefore, to maximize the power extraction from PV array, the panels need to be reconfigured for row current difference minimization. Row current minimization via Su Do Ku game theory do physical relocation of panels may cause laborious work and lengthy interconnecting ties. Hence, in this paper, an alternative to physical relocation based on particle swarm optimization (PSO) connected modules is proposed. In this method, the physical location of the modules remains unchanged, while its electrical connections are altered. Extensive simulations with different shade patterns are carried out and thorough analysis with the help of I-V, P-V curves is carried out to support the usefulness of the proposed method. The effectiveness of proposed PSO technique is evaluated via performance analysis based on energy saving and income generation. Further, a comprehensive comparison of various electrical array reconfiguration based is performed at the last to examine the suitability of proposed array reconfiguration method.
GaN-nanocolumn-based InGaN/GaN multiple quantum disk (MQD) light-emitting diodes (LEDs) with a novel columnar structure were fabricated on n-type (111) Si substrates. The n-GaN and InGaN/GaN MQD active region had isolated columnar structures, while the diameters were gradually increased in the p-GaN region by controlling the growth conditions. Consequently, the nanocolumn LED had a continuous surface without chasms. This novel structure enables p-type electrodes to be fabricated by the conventional method on top of nanocolumn devices while keeping the superior optical properties of the isolated nanocolumn active region. The nanocolumn LED showed clear rectifying behavior with a typical turn-on voltage of 2.5–3.0 V at room temperature. Electroluminescence was observed through semitransparent electrodes with various emission colors from green (530 nm) to red (645 nm).
We study the generalized Kompaneets equation (the kinetic equation for the photon distribution function taking into account Compton scattering by electrons) using a relativistically covariant formalism. Using the generalized Kompaneets equation, we derive an analytic expression for the Sunyaev-Zeldovich e ect, which takes into account up to terms, where is the relativistic expansion O(h e 5) h e \ k B T e /mc2 parameter and is the electron temperature. We carefully study the applicable region of the obtained T e analytic expression by comparing it with the result of the direct numerical integration. We conclude that the present analytic expression can be reliably applied to the calculation of the Sunyaev-Zeldovich e ect for keV, which is the highest electron temperature in the clusters of galaxies presently known. k B T e 15 Therefore, the present analytic expression can be applied to all known clusters of galaxies.
Columnar GaN nanostructures (GaN nanocolumns) were grown on Al 2 O 3 (0001) by RF-radical source molecular beam epitaxy (RF-MBE) through a self-organization process. The nanocolumns were grown at high density, with the c -axis maintained perpendicular to the substrate surface. The dependence of column diameter and density on growth conditions was systematically investigated. The average diameter was minimized to 53 nm and the density of the GaN nanocolumns was 130×10 12 columns per square meter.
Hydrated ionic liquids (ILs) were prepared by adding appropriate amounts of water to hydrophilic ILs. Some hydrated ILs show excellent solubilizing ability for proteins, keeping the basic properties of ILs. The solubility of cytochrome c (cyt c) depended on the structure of the component ions. When component anions have oxo acid residues, the resulting hydrated ILs solubilize cyt c quite well. In such hydrated ILs, the structure and activity of cyt c is influenced by the kosmotropicity of the component ions. We synthesized ILs from various ions having different kosmotropicity, including dihydrogen phosphate (dhp), dibutylphosphate, acetate, lactate, and methanesulfonate as anions. The activity of the dissolved cyt c depends on the permutations of kosmotropicity of the component ions. cyt c shows no structural change and retains its activity when dissolved in the hydrated choline dhp, which is an excellent combination of chaotropic cation and kosmotropic anion. Furthermore, cyt c dissolved in the hydrated choline dhp remained in a native state and was active after 18 months of storage at room temperature.
Data have been compiled on the cross sections for collisions of electrons and photons with nitrogen molecules (N2). For electron collisions, the processes considered are: total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational and electronic states, dissociation, and ionization. Ionization and dissociation processes are discussed for photon impact. Cross section data selected are presented graphically. Spectroscopic and other properties of the nitrogen molecule are summarized. The literature was surveyed through the end of 1984, but some more recent data are included when useful.
Using the epitaxial strain, the magnetic and electronic phases can be controlled for thin films of the manganites, La 1- x Sr x MnO 3 , grown on perovskite substrates with various lattice parameters. The strain-induced orbital-ordering (disordering) via coupling with the cooperative Jahn-Teller distortion produces different spin-structures, such as ferromagnetic, layer-type or chain-type antiferromagnetic states, and hence different magnetoelectronic characteristics. The spin-orbital phase diagram for La 1- x Sr x MnO 3 films has been obtained in the plane of strain-field ( c / a ratio) vs doping x , which can be quantitatively reproduced by the density-functional electronic-calculation.