Viewpoint Of Energetics Research Articles

Aggregation or dispersion of Si atoms in Al–Si alloys? from the view point of energetics

Aggregation or dispersion of Si atoms in Al–Si alloys? from the view point of energetics

Energy and Exergy Analyses of a Combined Infrared Radiation-Counterflow Circulation (IRCC) Corn Dryer

Energy consumption performance evaluation of an industrial grain dryer is an essential step to check its current status and to put forward suggestions for more effective operation. The present work proposed a combined IRCC dryer with drying capacity of 4.2 t/h that uses a novel drying technology. Moreover, the existing energy–exergy methodology was applied to evaluate the performance of the dryer on the basis of energy efficiency, heat loss characteristics, energy recovery, exergy flow and exegetic efficiency. The results demonstrated that the average drying rate of the present drying system was 1.1 gwater/gwet matter h. The energy efficiency of the whole drying system varied from 2.16% to 35.21% during the drying process. The overall recovered radiant energy and the average radiant exergy rate were 674,339.3 kJ and 3.54 kW, respectively. However, the average heat-loss rate of 3145.26 MJ/h indicated that measures should be put in place to improve its performance. Concerning the exergy aspect, the average exergy rate for dehydration was 462 kW and the exergy efficiency of the whole drying system ranged from 5.16% to 38.21%. Additionally, the exergy analysis of the components indicated that the combustion chamber should be primarily optimized among the whole drying system. The main conclusions of the present work may provide theoretical basis for the optimum design of the industrial drying process from the viewpoint of energetics.

Dissipation in Langevin Equation and Construction of Mobility Tensor from Dissipative Heat Flow

The rheological behavior of a material is strongly related to the energy dissipation, and the understanding and modeling of dissipation is important from the view point of rheology. To study rheological properties with some mesoscopic and macroscopic dynamics models, the modeling of dynamic equation which appropriately incorporates the dissipation is important. Although there are several methods to construct mesoscopic and macroscopic dynamic equations, such as the Onsager's method, their validity is not fully clear. In this work, we theoretically analyze the dissipation in a mesoscopic Langevin equation in detail, from the view point of stochastic energetics. We show that the dissipative heat flow from the heat bath to the system plays an important role in the mesoscopic dynamics. The dissipative heat flow is unchanged under the variable transform, and thus it is a covariant quantity. We show that we can construct the Langevin equation and also perform a coarse-graining based on the dissipative heat flow. We can derive the mobility tensor from the dissipative heat flow, and construct the Langevin equation by combining it and the free energy. Our method can be applied to various systems, such as the dumbbell model and the diffusion type equation for the density field, to give the coarse-grained dynamic equations for them.

Structure and energetics of carbon defects in SiC (0001)/SiO2 systems at realistic temperatures: Defects in SiC, SiO2, and at their interface

We report systematic first-principles calculations that reveal the atomic configurations, stability, and energy levels of carbon defects in SiC (0001)/SiO2 systems. We clarify the stable position (i.e., in SiC, SiO2, or at SiC/SiO2 interfaces) of defects depending on the oxidation environment (an oxygen-rich or -poor condition). At finite temperatures, the chemical potential of atomic species was corrected referring to thermochemical tables in order to obtain the temperature-dependent defect formation energies. Under an oxygen-rich condition, we found that the dicarbon antisite [(C2)Si] in SiC is one of the favorable defects at a typical oxidation temperature of 1600 K and it creates a localized level near the conduction band edge of SiC, being a critical defect for n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). A variety of carbon-dimer defects at a SiC/SiO2 interface, such as Si—CO—CO2, Si—CO—CO—Si, and Si—(CO)—CO2, are stable under the oxygen-rich condition at 1600 K, and they create localized levels relatively close to the valence band edge of SiC, thus being critical defects for p-channel MOSFETs. In the viewpoint of static energetics, our results suggest that the oxidation of SiC under a high-temperature oxygen-poor condition is effective in suppressing the generation of carbon defects.

Mechanical properties of upper torso rotation from the viewpoint of energetics during baseball pitching

This study aims to examine if upper torso rotation is caused mainly by pelvis rotation during baseball pitching from the viewpoint of energetics. Twelve right-handed males participated in this study. Five were and seven had been collegiate baseball pitchers, and all used an overarm style. They threw a baseball as fast and precisely as possible, and data from three strikes were used. A motion capture system consisting of 13 cameras and two force platforms was used to collect the data and calculate joint torques of the thoracic and the lumbar joint. The joint torque of the thoracic and the lumbar joint were calculated using a top-down and a bottom-up approach, respectively. Then, the mechanical energy generation and transfer by the torsional torques were quantified. The mechanical energy generation exerted by the torsional torques of the thoracic and lumbar joints were 0.03 ± 0.03 and 0.15 ± 0.04 J kg−1 m−1, respectively. The mechanical energy transfer exerted by the torsional torques of the thoracic and lumbar joints were 0.72 ± 0.19 and 0.88 ± 0.24 J kg−1 m−1, respectively. These results indicated that torsional torques transferred a substantial amount of mechanical energy from the pelvis to the upper torso. Furthermore, the findings indicate that the mechanical energy transfer exerted by the torsional torques was a major contributor to the upper torso rotation.

Exact solution of the generalized Peierls equation for arbitrary n-fold screw dislocation

The exact solution of the generalized Peierls equation is presented and proved for arbitrary n-fold screw dislocation. The displacement field, stress field and the energy of the n-fold dislocation are also evaluated explicitly. It is found that the solution defined on each individual fold is given by the tail cut from the original Peierls solution. In viewpoint of energetics, a screw dislocation has a tendency to spread the distribution on all possible slip planes which are contained in the dislocation line zone. Based on the exact solution, the approximated solution of the improved Peierls equation is proposed for the modified γ-surface.

Nickel complex engineered interface energetics for efficient photoelectrochemical hydrogen evolution over p-Si

Here we report a p-Si photocathode decorated with nickel complex Ni(TEOA)2Cl2 (Ni1) in acidic aqueous solution (pH=0.3) for photoelectrochemical (PEC) H2 generation. Compared to bare p-Si, p-Si/Ni1 electrode exhibits significantly enhanced PEC performance, with higher cathodic photocurrent and exceptional lower onset potential. A relatively high photocurrent density of 5.57mA/cm2 was obtained at 0.0V vs. reversible hydrogen electrode (RHE) under simulated 1 Sun illumination, which is even comparable to that of p-Si/Pt. Furthermore, the highly active p-Si/Ni1 electrode shows a remarkable stability over 24h. The possible catalysis mechanism of Ni1 for p-Si in the PEC H2 evolution process was also proposed in detail. The excellent PEC performance should be attributed to the Ni1 engineered p-Si/electrolyte interface energetics and the Ni1 catalyzed water reduction reaction, leading to robust hydrogen generation and excellent PEC stability. The present study made a deep insight into the engineered interface charge transfer and catalyst-driven surface water reduction processes at the semiconductor/electrolyte interface, which could provide some referable guidelines for fabricating highly efficient PEC system for solar H2 generation from the viewpoint of interface energetics engineering with metal complexes.

Cleanliness is next to godliness: mechanisms for staying clean.

Getting dirty is a fundamental problem, and one for which there are few solutions, especially across the enormous range of animal size. How do both a honeybee and a squirrel get clean? In this Review, we discuss two broad types of cleaning, considered from the viewpoint of energetics. Non-renewable cleaning strategies rely upon the organism as an energy source. Examples include grooming motions, wet-dog shaking or the secretion of chemicals. Renewable cleaning strategies depend on environmental sources of energy, such as the use of eyelashes to redirect incoming wind and so reduce deposition onto the eye. Both strategies take advantage of body hair to facilitate cleaning, and honeybees and squirrels, for example, each have around 3 million hairs. This hair mat increases the area on which particles can land by a factor of 100, but also suspends particles above the body, reducing their adhesion and facilitating removal. We hope that the strategies outlined here will inspire energy-efficient cleaning strategies in synthetic systems.

A theoretical study on the hydrogen transport mechanism in SrTiO3 perovskite. II. Scandium doping at titanium site

AbstractHybrid Kohn–Sham calculations are performed to clarify the proton‐conduction mechanism in Sc‐doped SrTiO3 perovskite, from the viewpoint of energetics and bonding. The calculated potential energy curves are discussed and a molecular‐orbital analysis performed. Much hydrogen can exist around doped scandium, where it is energetically stabilized. However, scandium‐doping has no energetic advantage in the activation energy for proton‐conduction. © 2012 Wiley Periodicals, Inc.

A diagnostic study of monsoon energetics for two contrasting years

Abstract. In the present study we made an attempt to explain the behavior of the southwest monsoon for two contrasting years, from the view point of energetics. As a test case we selected 2002 and 2003, which were weak and strong monsoon years, respectively, based on rainfall. The energy terms Kψ, Kχ and APE and the conversion terms f∇ψ. ∇χ, −ω'T' are calculated at 850 hPa level and also vertically integrated from 1000 hPa to 100 hPa. The results indicate that, the year of high energy (both KΨ, Kχ) i.e. 2002, does not give a good amount of rainfall compared to the good year i.e. 2003. The break period during the year 2002 has been clearly explained using the block diagrams. Periods of highest rainfall coincide with the positive conversions of f∇ψ. ∇χ and −ω'T'. Vertically integrated moisture fluxes during the break period of 2002, 2003 are also analyzed. The main reservoirs (sources and sinks) for the monsoon energy are also identified using block diagrams. Negative correlation between daily rainfall and energy terms in the year 2002 indicates its unusual behavior both in terms of energetics as well as precipitation. Positive correlations in the year 2003 represent strong monsoonal behavior. We calculated the climatology of the total kinetic energy at 850 hPa, vertically integrated (1000–100 hPa) for 30 years (1980–2009) and rainfall for 103 years (1901–2003) which clearly indicates that the monsoon is indeed a season of high energy for the South Asian region. Also the east- west direct thermal circulations are strongly related to the good and bad monsoon years.

Characteristics of the JRA-25 Dataset from the Viewpoint of Global Energetics

In this study, the global circulation represented by JRA-25 is examined from the viewpoint of global energetics, compared with ERA-40 and NCEP/NCAR reanalysis. Although the peak and slope of the spectrum for JRA-25 are consistent with those of the other datasets, the magnitude of energy or energy conversion is generally ERA-40 > JRA-25 > NCEP. For short waves, a rapid decrease of amplitude with increasing wave number is shown for NCEP/NCAR reanalysis and ERA-40. The energy conversion from zonal available potential energy to zonal kinetic energy, caused by zonal-mean meridional circulation, is the largest for JRA-25, which is the result of a large amount of cancellation of the local conversion term in the Hadley cell.

2P201 Interpretation of "Maxwell demon" in the induced potential motor molecule model from the viewpoint of the stochastic energetics(37. Molecular motor (II),Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)

2P201 Interpretation of "Maxwell demon" in the induced potential motor molecule model from the viewpoint of the stochastic energetics(37. Molecular motor (II),Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)

Thermodynamics of Nitroaromatic Compound Adsorption from Water by Smectite Clay

Nitroaromatic compounds enter the environment through their use as explosives, pesticides, solvents, and synthetic intermediates in the manufacturing of dyes, perfumes, and drugs. Recent studies have found that many nitroaromatic compounds are strongly retained by smectites, especially K+-saturated smectites. Sorption occurs when nitroaromatic compounds replace water associated with the clay and form complexes between K+ and -NO2 groups. This study seeks to further understand nitroaromatic-clay interactions from the viewpoint of energetics. Adsorption isotherms of 1,3-dinitrobenzene, 1,4-dinitrobenzene, and 1,3,5-trinitrobenzene from aqueous solution by K+- and Ca2+-saturated smectite (SWy-2) were measured at several temperatures between 4 degrees C and 37 degrees C to determine the molar differential adsorption enthalpies. Adsorption was found to be an exothermic process on both homoionic K+- and Ca2+-smectite. The smaller adsorption enthalpy on Ca-SWy-2 was consistent with its much smaller adsorption capacity for nitroaromatics compared to K-SWy-2. Our best estimate forthe enthalpy of 1,3,5-trinitrobenzene interactions with K-SWy-2 is -124 kJ/mol, which is referenced to gas-phase 1,3,5-trinitrobenzene, corrected forthe displacement of interlayer water, and can be directly compared with quantum chemical enthalpies from the literature. Our comparable estimates for 1,3- and 1,4-dinitrobenzene interaction enthalpies are near -90 kJ/mol. We conclude that our adsorption enthalpy results are consistent with the hypothesis that nitroaromatic compounds are sorbed strongly by K-smectites because they form inner- and/or outer-sphere complexes with K+ cations in clay interlayers. Indeed, the basal spacings of rewetted clay films in the presence of nitroaromatic compounds imply that water molecules cannot effectively compete with the adsorbed nitrobenzenes for reactive sites on K-SWy-2.

A Vibrational Analysis on Possible Peroxo Forms of Soluble Methane Monooxygenase

Abstract The vibrational structures for two possible peroxo intermediates of soluble methane monooxygenase (sMMO), in which O2 binds into the diiron(II) active site with end-on and side-on bridging modes, are analyzed from quantum chemical calculations at the B3LYP DFT level of theory. Dioxygen bridging modes should be controlled by carboxylate coordinations around the diiron active site. Two bridging carboxylato ligands are contained in the end-on peroxo complex, whereas one bridging carboxylato ligand is contained in the side-on peroxo complex. DFT calculations demonstrate that the end-on bridging mode into the diiron active site is energetically more stable than the side-on bridging mode. The end-on peroxo complex has a vibrational mode of O–O stretching at 909 cm−1, the isomer shift of which upon 18O2 substitution is 57 cm−1. The side-on peroxo complex exhibits a lower O–O stretching mode at 841 cm−1, and the isotope shift is 45 cm−1. The frequency of the O–O stretching mode and the 18O2 isotope shift are dependent on the dioxygen bridging modes in the active site of sMMO. The O–O stretching frequency in the end-on complex falls within the range measured in peroxo intermediates of other non-heme diiron enzymes and cis-μ-1,2 peroxo-bridged diiron(III) synthetic complexes. From the viewpoint of energetics and the vibrational frequencies, it is predicted that O2 should coordinate into the diiron active site of sMMO in an end-on cis-μ-1,2 fashion rather than a side-on fashion.

A non-radical mechanism for methane hydroxylation at the diiron active site of soluble methane monooxygenase

We propose a non-radical mechanism for the conversion of methane into methanol by soluble methane monooxygenase (sMMO), the active site of which involves a diiron active center. We assume the active site of the MMOH(Q) intermediate, exhibiting direct reactivity with the methane substrate, to be a bis(mu-oxo)diiron(IV) complex in which one of the iron atoms is coordinatively unsaturated (five-coordinate). Is it reasonable for such a diiron complex to be formed in the catalytic reaction of sMMO? The answer to this important question is positive from the viewpoint of energetics in density functional theory (DFT) calculations. Our model thus has a vacant coordination site for substrate methane. If MMOH(Q) involves a coordinatively unsaturated iron atom at the active center, methane is effectively converted into methanol in the broken-symmetry singlet state by a non-radical mechanism; in the first step a methane C-H bond is dissociated via a four-centered transition state (TS1) resulting in an important intermediate involving a hydroxo ligand and a methyl ligand, and in the second step the binding of the methyl ligand and the hydroxo ligand through a three-centered transition state (TS2) results in the formation of a methanol complex. This mechanism is essentially identical to that of the methane-methanol conversion by the bare FeO(+) complex and relevant transition metal-oxo complexes in the gas phase. Neither radical species nor ionic species are involved in this mechanism. We look in detail at kinetic isotope effects (KIEs) for H atom abstraction from methane on the basis of transition state theory with Wigner tunneling corrections.

A non-radical mechanism for methane hydroxylation at the diiron active site of soluble methane monooxygenase.

We propose a non-radical mechanism for the conversion of methane into methanol by soluble methane monooxygenase (sMMO), the active site of which involves a diiron active center. We assume the active site of the MMOH(Q) intermediate, exhibiting direct reactivity with the methane substrate, to be a bis(mu-oxo)diiron(IV) complex in which one of the iron atoms is coordinatively unsaturated (five-coordinate). Is it reasonable for such a diiron complex to be formed in the catalytic reaction of sMMO? The answer to this important question is positive from the viewpoint of energetics in density functional theory (DFT) calculations. Our model thus has a vacant coordination site for substrate methane. If MMOH(Q) involves a coordinatively unsaturated iron atom at the active center, methane is effectively converted into methanol in the broken-symmetry singlet state by a non-radical mechanism; in the first step a methane C-H bond is dissociated via a four-centered transition state (TS1) resulting in an important intermediate involving a hydroxo ligand and a methyl ligand, and in the second step the binding of the methyl ligand and the hydroxo ligand through a three-centered transition state (TS2) results in the formation of a methanol complex. This mechanism is essentially identical to that of the methane-methanol conversion by the bare FeO(+) complex and relevant transition metal-oxo complexes in the gas phase. Neither radical species nor ionic species are involved in this mechanism. We look in detail at kinetic isotope effects (KIEs) for H atom abstraction from methane on the basis of transition state theory with Wigner tunneling corrections.

Theoretical study on the structure and stability of the clusters of tropylium ion solvated by methanol molecules

Density functional theory (DFT) B3LYP calculations characterize the structure and stability of the clusters of tropylium ion (Tr +) coordinated by methanol molecules Tr +(MeOH) n with n=1–7. Methanol molecules are bound together through strong O–H⋯O type hydrogen bonds, resulting in a cyclic structure when n≥3, and the methanol cluster thus formed coordinates to Tr + through weak C–H⋯O type hydrogen bonds. Thus, the formation of the Tr +(MeOH) n clusters is mediated by two kinds of hydrogen bonds. Calculated distances of the O–H⋯O hydrogen bonds lie in the range 1.570–1.991 Å (1.712 Å in average) while those of the C–H⋯O hydrogen bonds lie in the range 2.083–2.319 Å (2.160 Å in average). Mass spectroscopic experiments demonstrated that Tr +(MeOH) 4 is a dominant, magic-numbered species and that Tr +(MeOH) 3 and Tr +(MeOH) 5 are minor [Chemical Communication, (2001) in press]. The experimental result is analyzed from the viewpoint of energetics. The specific size effect on the stability of Tr +(MeOH) n is a direct consequence of the stability of the (MeOH) n fragment itself.

Energy hierarchy and urban landscape system

The study of ecosystems suggests principles by which the flow of energy generates hierarchies in all systems. From viewpoint of ecological energetics, urban system lies on the highest level of ecosystem hierarchy. The main objective of this paper is to study the effect of energy flows on the hierarchies and spatial organization of urban zonation. This research uses Taipei metropolitan region as the area for the case study. “Emergy” is used as the principal conceptual tool for energy analysis; “transformity” is used to measure the hierarchies of land uses and urban landscape systems. Based on the calculation of the spatial distribution of energy flows, using GIS, the empower density and transformity increase from rural to urban center. In order to delineate zones of different energetics, the 1178 administrative districts of the Taipei metropolitan region are used as units for multivariate classification, in which 19 variables of energy flows are condensed into four factors. The factor scores of each districts are then used as input for cluster analysis and discriminate analysis. As a result, different energy structures, and subsequently, different types and amount of energy flows tend to associate with different intensities of urbanization. The Taipei metropolitan region is classified into six energetic zones: mixed-use urban core; high density urban residential district; service and manufacturing urban district; agricultural district, newly developed suburban district; and natural area. The calculation of transformity and emergy indices further establish the hierarchical order of these zones. The distribution of the six energetic zones, reveals the spatial energetic hierarchies of Taipei metropolitan region. The implication of energetic characteristics to planning practice is also discussed to conclude this research.

Monte carlo method applied in the search for low‐energy conformations of βαβαβ structures

AbstractA Monte Carlo approach was used to find low‐energy conformations of sequentially linked βαβαβ structures to be used as initial conformations in energy minimizations. Only L‐type amino acids were used in the study. The composition of the linked polypeptide chain was H(Val)6(R)4(Ala)14(R)4(Val)6(R)4(Ala)14(R)4(Val)6OH. A loop region was represented by (R)4, where R was either Gly or Ala. Two types of connections were considered: connections between nearest neighbor strands in the β‐sheet, and connections between β‐strands separated by one intervening β‐strand. The loop energy and the total energy of the α‐helical and β‐strand segments in the energy‐minimized structures were analyzed. The orientations of the secondary structural elements were characterized. In agreement with the handedness observed by experiment, all right‐handed crossover conformations were computed to have lower conformational energies than the corresponding left‐handed crossover conformations. The energy gaps between the corresponding loop energies also favored right‐handed conformations. Furthermore, the packing angles between the α‐helix axis and the β‐sheet axis are also in good agreement with experimental observations. Therefore the right‐handedness of the observed βαβαβ structure can be understood from the viewpoint of energetics.

Electrical and mechanical activity of the diaphragm accompanying body position in severe chronic obstructive pulmonary disease.

Using a special gastroesophageal catheter, electromyographic measurements of the diaphragm (Edi) and transdiaphragmatic pressure (Pdi) were taken in the supine, standing, erect sitting, and leaning forward (sitting) positions in 8 normal subjects and 6 patients with severe chronic obstructive pulmonary disease (COPD) with marked hyperinflation and low fat diaphragms. Four patients had pronounced postural relief of their dyspnea from assuming the supine and/or leaning forward positions. All 8 normal subjects and 4 of the 6 patients with COPD showed substantial (2- to 5-fold) increases in delta Edi, the phasic inspiratory amplitude of Edi, on assuming the standing and erect sitting postures. In the normal subjects, delta Pdi, the phasic inspiratory increment in Pdi, was maintained in all 4 postures, whereas in all patients with COPD, it decreased significantly in the erect sitting and standing postures. In 2 of the 6 patients with COPD, the delta Edi did not increase in the erect postures. This suggested that in these patients a reflex, which normally compensates for reduced diaphragmatic efficiency because of shortened muscle fibers in the erect postures, was not operating. Although it is not clear what mechanism(s) might account for suppression of this compensatory reflex, such reflex suppression might be advantageous from the viewpoint of diaphragmatic muscle energetics. The diaphragm would be thus spared energetically wasteful attempts to accomplish a fatiguing mechanical task.