Process Of SF Research Articles

Toward Silicon‐Matched Singlet Fission: Energy‐Level Modifications Through Steric Twisting of Organic Semiconductors

AbstractSinglet fission (SF) is a potential avenue for augmenting the performance of silicon photovoltaics, but the scarcity of SF materials energy‐matched to silicon represents a barrier to the commercial realization of this technology. In this work, a molecular engineering approach is described to increase the energy of the S1 and T1 energy levels of diketopyrrolopyrrole derivatives such that the energy‐level requirements for exothermic SF and energy‐transfer to silicon are met. Time‐resolved photoluminescence studies show that the silicon‐matched materials are SF active in the solid state, forming a correlated triplet pair 1(TT) – a crucial intermediate in the SF process – as observed through Herzberg‐Teller emission from 1(TT) at both 77 K and room temperature. Transient electron paramagnetic resonance studies show that the correlated triplet pair does not readily separate into the unbound triplets, which is a requirement for energy harvesting by silicon. The fact that the triplet pair do not separate into free triplets is attributed to the intermolecular crystal packing within the thin films. Nevertheless, these results demonstrate a promising route for energy‐tuning silicon‐matched SF materials.

Veil of the Charge Transfer State in Bay-Annulated Indigo-Based Donor-Acceptor Systems: Charge Separation versus Singlet Fission.

Bay-annulated indigo (BAI) is a new potential SF-active building block, which has aroused great interest in the design of highly stable singlet fission materials. However, singlet fission of unfunctionalized BAI is inactive due to the inappropriate energy levels. Herein, we seek to develop a new design strategy by introducing the charge transfer interaction to tune the exciton dynamics of BAI derivatives. A new donor-acceptor molecule (TPA-2BAI) and two control molecules (TPA-BAI and 2TPA-BAI) were designed and synthesized to unravel the veil of CT states in tuning the excited-state dynamics of BAI derivatives. Transient absorption spectroscopy studies show that CT states are generated immediately following the excitation. However, the low-lying CT states induced by strong donor-acceptor interactions result in them acting as trap states and inhibiting the SF process. These results show that the low-lying CT state is detrimental to SF and provide insight into the design of CT-mediated BAI-based SF materials.

Homogenous Sono-Fenton reaction can trigger long term bactericidal effect against Acinetobacter baumannii due to residual stress induced by reactive oxygen species

Gastrointestinal diseases caused by microbial contamination of water has been one of the enduring public health challenges of the mankind, wherefore demands continual innovation in the contemporary water treatment techniques. Here, a systematic study was carried out to elucidate the bactericidal mechanism of ultrasound assisted Fenton reaction (Sono-Fenton: SF) against multidrug resistant Acinetobacter baumannii. Inactivation of ≈5 × 106 CFU/mL of A. baumannii was achieved within 90 min of SF under weak acidic conditions using 20 mg L-1 of H2O2 and 2 mg L-1 of Fe2+. Having more than 99 % inactivation efficiency, no reactivation of the bacteria was observed for 96 h. After SF, a combination of ultrasound and H2O2 was found to be more efficient although complete inactivation was not achieved within the same time frame. Experimental evidence suggests the generation of multiple reactive oxygen species (ROS) such as H2O2, •OH and O2•–. The synergistic effect of ROS and ultrasound may have resulted in the membrane damage of the bacteria as evident from the electron microscopy analysis. Interestingly, our data also suggests that the residual stress associated with SF could have long term bactericidal effect and is influenced by incubation temperature. Comparative transcriptomic analysis showed that NirD/YgiW/YdeI family stress tolerance protein, KGG domain containing proteins, and PspC domain containing proteins, all known to control the stress induced responses in bacteria was significantly upregulated after SF treatment. Additionally, genes regulating transcription (GntR) and translation (rpsQ) have been downregulated which may induce a nutrient and metabolite limiting conditions in the bacterial cell. The bacterial inactivation ability of SF process was further validated with real water samples collected from natural systems and therefore, advocate the possible real-world applications.

Factors influencing maize stemflow in western Liaoning, China

AbstractStemflow (SF) is an important source of water for maize (Zea mays L.) growing in arid areas, and is very important for agricultural water management. However, the results of previous studies in different regions are quite different. There is also a lack of in‐depth research on the SF process of maize at each growth stage. The purpose of this study was to analyze the effects of rainfall characteristics and maize morphology on SF during the entire maize‐growing period, quantify the stemflow rate (SR) in western Liaoning, analyze the differences in the maize SF process during different growing periods, and establish a multiple regression model for the different growth stages to predict SF. The results showed that the SR in the study area was 12.62%–43.44% during the 28 rainfall events from 2015 to 2016, and the mean SR was 32.80%. The mean SR during the jointing, tasseling, and mature stages were 24.10%, 42.72%, and 35.37%, respectively. SF generally increases with increased precipitation, and with an increase in the leaf area index, but the effects of various factors on SF differed between the early (jointing) and later stages (tasseling and maturity) of maize growth. A multiple regression model of the different growth stages was established to better predict SF in the research region. This study is significant as it improves local farmland water cycle theory and improves the efficiency of irrigation water. In the next step, the effects of leaf angle and canopy coverage warrant further investigation.

Possibilities and Limitations of the Sono-Fenton Process Using Mid-High-Frequency Ultrasound for the Degradation of Organic Pollutants.

Mid-high-frequency ultrasound (200-1000 kHz) eliminates organic pollutants and also generates H2O2. To take advantage of H2O2, iron species can be added, generating a hybrid sono-Fenton process (sF). This paper presents the possibilities and limitations of sF. Heterogeneous (a natural mineral) and homogeneous (Fe2+ and Fe3+ ions) iron sources were considered. Acetaminophen, ciprofloxacin, and methyl orange were the target organic pollutants. Ultrasound alone induced the pollutants degradation, and the dual competing role of the natural mineral (0.02-0.20 g L-1) meant that it had no significant effects on the elimination of pollutants. In contrast, both Fe2+ and Fe3+ ions enhanced the pollutants' degradation, and the elimination using Fe2+ was better because of its higher reactivity toward H2O2. However, the enhancement decreased at high Fe2+ concentrations (e.g., 5 mg L-1) because of scavenger effects. The Fe2+ addition significantly accelerated the elimination of acetaminophen and methyl orange. For ciprofloxacin, at short treatment times, the degradation was enhanced, but the pollutant complexation with Fe3+ that came from the Fenton reaction caused degradation to stop. Additionally, sF did not decrease the antimicrobial activity associated with ciprofloxacin, whereas ultrasound alone did. Therefore, the chemical structure of the pollutant plays a crucial role in the feasibility of the sF process.

Simple Evaluation of Singlet Fission Couplings for Interacting Dimer Systems

AbstractSinglet fission (SF) could potentially generate two triplet excitations from the absorption of a single photon, which can be applied to significantly enhance the energy conversion efficiency of solar cells. Efficiency of SF for molecular dimers depend on couplings between electronic configurations, however, available theoretical methods for quantitative evaluations of these couplings often require high computational cost and thus it is still difficult to explore geometrical dependence of SF performance for molecular dimers. Herein, we present a direct derivation of the couplings relevant to SF process on the basis of rigorously localized dimeric orbitals. We then systematically show that the SF rates can be correlated with a SF overlap factor that can be easily evaluated from monomeric molecular orbitals. Furthermore, we demonstrate the validity of the overlap factor as a quantitative descriptor of effective SF coupling based on comparative studies on slip‐stacked ethylene and tetracene dimers. With the validity confirmed, we applied the descriptor to investigate a large family of polycyclic aromatic hydrocarbons to reveal dimer geometries that could potentially exhibit highly efficient SF. Our results provide a theoretical tool that could significant increase the speed and reliability of the discovery process for efficient organic SF materials.

Multi-product biorefinery from Arthrospira platensis biomass as feedstock for bioethanol and lactic acid production

With the aim to reach the maximum recovery of bulk and specialty bioproducts while minimizing waste generation, a multi-product biorefinery for ethanol and lactic acid production from the biomass of cyanobacterium Arthrospira platensis was investigated. Therefore, the residual biomass resulting from different pretreatments consisting of supercritical fluid extraction (SF) and microwave assisted extraction with non-polar (MN) and polar solvents (MP), previously applied on A. platensis to extract bioactive metabolites, was further valorized. In particular, it was used as a substrate for fermentation with Saccharomyces cerevisiae LPB-287 and Lactobacillus acidophilus ATCC 43121 to produce bioethanol (BE) and lactic acid (LA), respectively. The maximum concentrations achieved were 3.02 ± 0.07 g/L of BE by the MN process at 120 rpm 30 °C, and 9.67 ± 0.05 g/L of LA by the SF process at 120 rpm 37 °C. An economic analysis of BE and LA production was carried out to elucidate the impact of fermentation scale, fermenter costs, production titer, fermentation time and cyanobacterial biomass production cost. The results indicated that the critical variables are fermenter scale, equipment cost, and product titer; time process was analyzed but was not critical. As scale increased, costs tended to stabilize, but also more product was generated, which causes production costs per unit of product to sharply decrease. The median value of production cost was US$ 1.27 and US$ 0.39, for BE and LA, respectively, supporting the concept of cyanobacterium biomass being used for fermentation and subsequent extraction to obtain ethanol and lactic acid as end products from A. platensis.

Multiexciton state of singlet fission in triisopropylsilylethynyl‐pentacene

AbstractSinglet fission (SF) is a spin‐allowed conversion process, in which one singlet exciton is replaced by a pair of triplet excitons resided on adjacent molecules. To rationalize this phenomenon, a multiexcitonic spin‐zero triplet‐pair state is generally hypothesized as an intermediate state for SF. However, the details of its formation during the fission process, and its subsequent evolution over time are still remain unclear. Thus, this work provides a model of the SF system for triisopropylsilylethynyl‐pentacene by using femtosecond time‐resolved transient absorption spectroscopy. A mixed state of singlet and multiexciton, which mediates the ultrafast SF process is directly observed. This work represents a new viewpoint for the research on SF intermediates.

Direct, Mediated, and Delayed Intramolecular Singlet Fission Mechanism in Donor-Acceptor Copolymers.

Donor-acceptor (D-A) extended copolymers have shown great potential to be exploited for intramolecular singlet fission (iSF) because of their modular tunability and intrinsic ability to incorporate low-lying charge-transfer (CT) and a triplet-pair (1TT) states. While the SF mechanism has been widely debated in homo- and heterodimers, little is known about the singlet splitting process in A-D-A copolymer trimers. Unlike traditional two-site SF, the process of iSF in D-A copolymers involves three molecular units consisting of two A's and one D following an A-D-A polymeric chain. This scenario is, therefore, different from that of the homodimer analogues in terms of which states (if any) may drive the SF process. In this work, we identify how singlet splitting occurs in prototypical iSF D-A copolymer poly(benzodithiophene-alt-thiophene-1,1-dioxide) by means of wave packet propagations on the basis of the linear vibronic coupling model Hamiltonian. Our results reveal that three different mechanisms drive the S1 → 1TT population transfer via antisymmetric and symmetric vibrational motion, including two favorable mechanisms of direct and mediated interactions, as well as a parasitic decay pathway that potentially delays the process. Remarkably, we uncover the interplay between an upper state of marked multiexcitonic character and a low-lying CT state in balancing the splitting efficiency, which anticipates their major role in defining future guidelines for the molecular design of D-A copolymers for iSF.

SDSS-IV MaNGA: effects of morphology in the global and local star formation main sequences

ABSTRACT We study the global star formation rate (SFR) versus stellar mass (M*) correlation, and the spatially resolved SFR surface density (ΣSFR) versus stellar mass surface density (Σ*) correlation, in a sample of ∼2000 galaxies from the MaNGA MPL-5 survey. We classify galaxies and spatially resolved areas into star forming and retired according to their ionization processes. We confirm the existence of a star-forming main sequence (SFMS) for galaxies and spatially resolved areas, and show that they have the same nature, with the global as a consequence of the local one. The latter presents a bend below a limit Σ* value, ≈3 × 107 M$\odot$ kpc−2, which is not physical. Using only star-forming areas (SFAs) above this limit, a slope and a scatter of ≈1 and ≈0.27 dex are determined. The retired galaxies/areas strongly segregate from their respective SFMSs, by ∼−1.5 dex on average. We explore how the global/local SFMSs depend on galaxy morphology, finding that for star-forming galaxies and SFAs, there is a trend to lower values of star formation activity with earlier morphological types, which is more pronounced for the local SFMS. The morphology not only affects the global SFR due to the diminish of SFAs with earlier types, but also affects the local SF process. Our results suggest that the local SF at all radii is established by some universal mechanism partially modulated by morphology. Morphology seems to be connected to the slow aging and sharp decline of the SF process, and on its own it may depend on other properties as the environment.

The validation of the Dutch OAB-q SF: An overactive bladder symptom bother and health-related quality of life short-form questionnaire.

The overactive bladder quality of life short-form questionnaire (OAB-q SF) evaluates both symptom bother and health-related quality of life in patients with OAB, a highly prevalent disease. The objective of this study was to translate and validate a Dutch version of the OAB-q SF. The translation into Dutch and validation process of the OAB-q SF was performed according to standardized guidelines. Patients with OAB who visited the department of Urology outpatient clinic completed the questionnaires OAB-q SF, European Quality of life 5-Dimension 5-Level questionnaire (EQ-5D-5L), Urogenital Distress Inventory 6 (UDI-6), and the International Consultation on Incontinence Questionnaire Overactive Bladder (ICIQ-OAB) at baseline (test) and 2 weeks later (retest). A reference group from the department of Allergology outpatient clinic completed the same questionnaires once. The evaluated measurement properties included content validity, internal consistency, reproducibility, criterion validity, and construct validity. Fifty-two patients were included in the study group and 51 references were included. The content validity was adequate and the internal consistency was excellent (Cronbach's α > 0.80). The reproducibility was good with intraclass correlation coefficients higher than 0.70. Patient's OAB-q SF scores were moderately to strongly correlated with the UDI-6, ICIQ-OAB, and the EQ-5D-5L confirming the criterion validity. A good construct validity was demonstrated with significant higher scores of the OAB-q SF score in patients compared to references. The Dutch OAB-q SF is a reliable and valid measure to evaluate symptom bother and health-related quality of life in patients with OAB.

Application of Food-Grade Proteolytic Enzyme for the Hydrolysis of Regenerated Silk Fibroin fromBombyx mori

In vitrobiodegradation ofBombyx morisilk fibroin (SF) was studied using food-grade proteolytic enzymes to replace acid hydrolysis. Based on the residual protein quantity and yield of amino acids (AAs) after enzymatic hydrolysis, we evaluated the proteolytic enzyme process of SF. FoodPro and Alcalase that are classified as alkaline proteases are selected as two of the best candidate enzymes for hydrolysis of SF. The activity of these enzymes exhibits a broad range of pH (6.5 to 9.0) and temperature (50°C to 65°C). The single enzyme treatment of SF using FoodPro exhibited a hydrolytic efficiency of 20–25%, and >2 g/L AAs were released after reaction for 3 h. A 2-stage enzymatic treatment using a combination of FoodPro and Flavourzyme in a sequence for a reaction time of 6 h was developed to enhance the efficiency of the proteolytic process. The yield of AAs and residual protein quantity in the enzymatic hydrolysates obtained from FoodPro-treated regenerated SF in the 1st step was 2,040 ± 23.7 mg/L and 70.6%, respectively. The yield of AAs was > two-fold (4,519 ± 42.1 mg/L), whereas the residual protein quantity decreased to 55.1% after the Flavourzyme treatment (2nd step) compared to those of the single FoodPro treatment. In the mixed treatment by simultaneously using FoodPro and Flavourzyme, approximately 45% of SF was degraded and 4.5 g/L of AAs were released within 3 h of reaction time. The regenerated SF and its enzymatic hydrolysates were characterized by performing UV-visible spectra, gel electrophoresis, and size-exclusion chromatography analyses. In the 2-stage treatment using FoodPro initially and subsequently Flavourzyme, the aggregates and high molecular weight proteins of SF were dissociated and degraded into the low molecular weight proteins/peptides (10–15 kDa and 27 kDa). SF hydrolysates as functional food might be enzymatically produced using the commercial food-grade proteolytic enzymes.

The evolution of interacting spiral galaxy NGC 5194

NGC 5194 (M51a) is a grand-design spiral galaxy and undergoing interactions with its companion. Here we focus on investigating main properties of its star-formation history (SFH) by constructing a simple evolution model, which assumes that the disc builds up gradually by cold gas infall and the gas infall rate can be parameterizedly described by a Gaussian form. By comparing model predictions with the observed data, we discuss the probable range for free parameter in the model and then know more about the main properties of the evolution and SFH of M51a. We find that the model predictions are very sensitive to the free parameter and the model adopting a constant infall-peak time $t_{\rm p}\,=\,7.0{\rm Gyr}$ can reproduce most of the observed constraints of M51a. Although our model does not assume the gas infall time-scale of the inner disc is shorter than that of the outer disc, our model predictions still show that the disc of M51a forms inside-out. We find that the mean stellar age of M51a is younger than that of the Milky Way, but older than that of the gas-rich disc galaxy UGC 8802. In this paper, we also introduce a 'toy' model to allow an additional cold gas infall occurred recently to imitate the influence of the interaction between M51a and its companion. Our results show that the current molecular gas surface density, the SFR and the UV-band surface brightness are important quantities to trace the effects of recent interaction on galactic SF process.

TYPICAL MEXICAN AGROINDUSTRIAL RESIDUES AS SUPPORTS FOR SOLID-STATE FERMENTATION

Biological wastes contain several reusable substanc es of high value such as soluble sugars and fiber. Direct disposal of such wastes to soil or landfill causes serious environmental problems. Thus, the development of potential value-added processes for these wastes is highly attractive. These biological wastes can be used as support-substrates in Solid-State Fermentation (SSF ) to produce industrially relevant metabolites with great economical advantage. In addition, it is an environ ment friendly method of waste management. In this study were analyzed six different Mexican agro industrial residues to evaluate their suitability as support- substrate in SSF, between physicochemical properties that have included Water Absorption Index (WAI), Critical Moisture Point (CHP) and Packing Density (PD). The selection of an appropriate solid substrate plays a n important role in the development of an efficient S SF process. The results provided important knowledge about the characteristics of these materials reveal ing their potential for use in fermentation process es.

Correlation analysis between formation process of SF6 decomposed components and partial discharge qualities

To obtain relationship between concentration of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> decomposed characteristic components (or their concentration ratio) during the formation process and partial discharge qualities and pulse repetition rate, this paper used needle-plate electrode to simulate outthrust insulation fault and conducted a serial of experiments. First, the SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> decomposition characteristic under different PD strengths is obtained. Then this paper defines average discharge qualities per second as Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SEC</sub> . It considers both apparent discharge qualities and discharge pulse repetition rate, and analyzes the relation feature between SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> decomposition characteristic (both concentration of component and their effective formation rates RRMS) and Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SEC</sub> . Besides, it proposes C(SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )/C(SOF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) as the energy characteristic ratio (ER) to represent PD energy, and defines the effective energy characteristic ratio as (ER <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> ). Moreover, it achieves the inner correlation feature between Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SEC</sub> and all the characteristic component concentration, the RRMS of each characteristic component and ERRMS. The results show that: since number of C atoms from stainless steel surface and content of trace H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O and O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> in gas chamber were limited, both decomposed component concentration and component concentration ratio accords with the famous "Logistic Population Model" growth trend in ecology, which means they present "S"-curve increase with Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SEC</sub> . The proposed ER can effectively indicate the amount of PD energy and the defined ER <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> can objectively reveal the variance regularity of PD energy with Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SEC</sub> . Hence, the correlation mathematic formula between ER <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> and Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SEC</sub> is obtained and ER <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> can be used as the new characteristic parameter to represent PD energy. It establishes the foundation for the further fault diagnosis research.

THE ARECIBO LEGACY FAST ALFA SURVEY: THE GALAXY POPULATION DETECTED BY ALFALFA

Making use of HI 21 cm line measurements from the ALFALFA survey (alpha.40) and photometry from the Sloan Digital Sky Survey (SDSS) and GALEX, we investigate the global scaling relations and fundamental planes linking stars and gas for a sample of 9417 common galaxies: the alpha.40-SDSS-GALEX sample. In addition to their HI properties derived from the ALFALFA dataset, stellar masses (M_*) and star formation rates (SFRs) are derived from fitting the UV-optical spectral energy distributions. 96% of the alpha.40-SDSS-GALEX galaxies belong to the blue cloud, with the average gas fraction f_HI = M_HI/M_* ~ 1.5. A transition in SF properties is found whereby below M_* ~ 10^9.5 M_sun, the slope of the star forming sequence changes, the dispersion in the specific star formation rate (SSFR) distribution increases and the star formation efficiency (SFE) mildly increases with M_*. The evolutionary track in the SSFR-M_* diagram, as well as that in the color magnitude diagram are linked to the HI content; below this transition mass, the star formation is regulated strongly by the HI. Comparison of HI- and optically-selected samples over the same restricted volume shows that the HI-selected population is less evolved and has overall higher SFR and SSFR at a given stellar mass, but lower SFE and extinction, suggesting either that a bottleneck exists in the HI to H_2 conversion, or that the process of SF in the very HI-dominated galaxies obeys an unusual, low efficiency star formation law. A trend is found that, for a given stellar mass, high gas fraction galaxies reside preferentially in dark matter halos with high spin parameters. Because it represents a full census of HI-bearing galaxies at z~0, the scaling relations and fundamental planes derived for the ALFALFA population can be used to assess the HI detection rate by future blind HI surveys and intensity mapping experiments at higher redshift.

HIGH- AND LOW-MASS STAR-FORMING REGIONS FROM HIERARCHICAL GRAVITATIONAL FRAGMENTATION. HIGH LOCAL STAR FORMATION RATES WITH LOW GLOBAL EFFICIENCIES

We investigate the properties of star-forming regions in a previously published numerical simulation of molecular cloud formation out of compressive motions in the warm neutral atomic interstellar medium, neglecting magnetic fields and stellar feedback. We study the properties (density, total gas + stars mass, stellar mass, velocity dispersion, and star formation rate (SFR)) of the cloud hosting the first local, isolated star formation event and compare them with those of the cloud formed by the central, global collapse event. In this simulation, the velocity dispersions at all scales are caused primarily by infall motions rather than by random turbulence. We suggest that the small-scale isolated collapses may be representative of low- to intermediate-mass star-forming regions, with gas masses (M gas) of hundreds of solar masses, velocity dispersions σ v ~ 0.7 km s–1, and SFRs ~3 × 10–5 M ☉ yr–1, while the large-scale, massive ones may be representative of massive star-forming regions, with M gas of thousands of solar masses, σ v ~ a few km s–1, and SFRs ~3 × 10–4 M ☉ yr–1. We also compare the statistical distributions of the physical properties of the dense cores appearing in the central region of massive collapse with those from a recent survey of the massive star-forming region in the Cygnus X molecular cloud, finding that the observed and simulated distributions are in general very similar. However, we find that the star formation efficiency per free-fall time (SFEff) of the high mass region, similar to that of OMC-1, is low, ~0.04. In the simulated cloud, this is not a consequence of a slow SFR in a nearly hydrostatic cloud supported by turbulence, but rather of the region accreting mass at a high rate. Thus, we find that measuring a low SFEff may be incorrectly interpreted as implying a lifetime much longer than the core's local free-fall time, and an SFR much slower than that given by the free-fall rate, if the accretion is not accounted for. We suggest that rather than requiring a low value of the SFEff everywhere in the Galaxy, attaining a globally low specific SFR requires star formation to be a spatially intermittent process, so that most of the mass in a giant molecular cloud (GMC) is not participating in the SF process at any given time. Locally, the specific SFR of a star-forming region can be much larger than the global GMC's average.

重畳超仕上げに関する研究(第1報)(機械要素,潤滑,工作,生産管理など)

The objective or this investigation is to clarify a new and high efficient mirror machining, that can be named superposition superfinishing (SSF process) using a fine abrasive stone. In this machining, at first process (SVC process: superposition vibration cutting) high efficient cutting is achieved with simultaneously providing (20〜50Hz) low frequent vibration and ultrasonic vibration above 20kHz on fine abrasive stone, and at next process (SF process: superfinishing) mirror surface can be obtained in a short time with only low frequent vibration. In this report, it is shown that basic machining characteristics and possibility of high efficient mirror machining on this new process are practically confirmed by several experiments.

Transient Response Simulation of Downstream Thermofluid Field in a Gas Circuit Breaker during Current Interruption

A transient response of SF 6 thermofluid field inside the exhaust tube in a Gas Circuit Breaker under high temperature, high pressure and high velocity conditions is analyzed by taking compressible effect and some realistic processes into account related to the available experimental data of GCB test facility. Furthermore, computational simulation is conducted to clarify the effective cooling process of SF 6 hot gas flow inside the exhaust tube for transient time to avoid the SF 6 hot gas breakdown near exhaust tube exit after the arc current interruption. It is found that the SF 6 hot gas flow can be effectively cooled down for the rough inside wall of exhaust tube due to the separation of SF 6 hot gas flow from the inside wall and also active mixing with upstream cold gas. The effect of roughness pattern on the real time thermofluid field of SF 6 hot gas flow and possible breakdown region are also clarified. Finally, the computed temperature in GCB shows the good agreement with the available experimental data for smooth surface of exhaust tube.

Formation and Evolution of Disk Galaxies

We have developed a semianalitical approach to study galaxy formation and evolution in the cosmological context. Disk galaxies (dark matter halo+luminous disk) are considered to be formed through an extended process of gravitational collapse, whose character is determined by the statistical properties of the density fluctuation field assumed here to be Gaussian. Gas disks in centrifugal equilibrium within the collapsing dark halos are built up (detailed angular momentum conservation is assumed), and their galactic evolution is calculated with a model which consider all the gravitational interactions, the hydrodynamics of the ISM, and the SF process. A bulge as product of stellar disk gravitational instabilities is constructed. To study general behaviors a Gaussian σ8 = 1 SCDM model is used. For a given mass one obtains a range of dark matter configurations. The average case is in excellent agreement with results of cosmological N-body simulations. The slope of the mass-velocity relation agrees with the slope of the H- and I-band Tully-Fisher relations, but the velocities are too high. This problem dissapears if the power spectrum is renormalized to σ8 = 0.57, suggesting that the TF relation is result of the natural extension to galactic scales of the galaxy distribution power spectrum, and that on the basis of its origin are the cosmological initial conditions. The scatter on the mass-velocity relation is realistic. The models predict disk exponential surface brightness (SB) profiles, nearly flat rotation curves, and negative radial gradients in the B-V color. The obtained, gas fractions, B-V colors, central SBs μB0, bulge-to-disk (b/d) ratios, and rotation velocities (for σ8 = 0.57) are in agreement with observations, and their correlations are similar to those which define the Hubble sequence, including the LSB galaxies. These properties and correlations are the product of the combination of three fundamental physical factors: the mass, the mass aggregation history (MAH), and the initial angular momentum. The intensive properties are almost invariant to the mass, the MAH determines the B-V color, and the spin parameter λ mainly influences on μB0, and b/d ratio.