Calculation Of Energy Density Research Articles

Molecular modeling study on surface, thermal, mechanical and gas diffusion properties of chitosan

AbstractThe motivation of this work is to provide reliable and accurate modeling studies of the physical (surface, thermal, mechanical and gas diffusion) properties of chitosan (CS) polymer. Our computational efforts have been devoted to make a comparison of the structural bulk properties of CS with similar type of polymers such as chitin and cellulose through cohesive energy density, solubility parameter, hydrogen bonding, and free volume distribution calculations. Atomistic modeling on CS polymer using molecular mechanics (MM) and molecular dynamics (MD) simulations has been carried out in three dimensionally periodic and effective two dimensionally periodic condensed phases. From the equilibrated structures, surface energies were computed. The equilibrium structure of the films shows an interior region of mass density close to the value in the bulk state. Various components of energetic interactions have been examined in detail to acquire a better insight into the interactions between bulk structure and the film surface. MD simulation (NPT ensemble) has also been used to obtain polymer specific volume as a function of temperature. It is demonstrated that these V–T curves can be used to locate the volumetric glass transition temperature (Tg) reliably. The mechanical properties of CS have been obtained using the strain deformation method. Diffusion coefficients of O2, N2, and CO2 gas molecules at 300 K in CS have been estimated. The calculated properties of CS are comparable with the experimental values reported in the literature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1260–1270, 2007

The energy density of jellyfish: Estimates from bomb-calorimetry and proximate-composition

Two techniques are described to calculate energy densities for the bell, gonad and oral arm tissues of three scyphozoan jellyfish ( Cyanea capillata, Rhizostoma octopus and Chrysaora hysoscella). First, bomb-calorimetry was used, a technique that is readily available and inexpensive. However, the reliability of this technique for gelatinous material is contentious. Second, further analysis involving the more labour intensive proximate-composition analysis (protein, fat and carbohydrate) was carried out on two species ( C. capillata and R. octopus). These proximate data were subsequently converted to energy densities. The two techniques (bomb-calorimetry and proximate-composition) gave very similar estimates of energy density. Differences in energy density were found both amongst different species and between different tissues of the same species. Mean (± S.D.) energy density estimates for whole animals from bomb-calorimetry were 0.18 ± 0.05, 0.11 ± 0.04, and 0.10 ± 0.03 kJ g wet mass − 1 for C. capillata, R. octopus, and C. hysoscella respectively. The implications of these low energy densities for species feeding on jellyfish are discussed.

Electron promotion and electronic friction in atomic collision cascades

We present a computer simulation model for the space- and time-resolved calculation of electronic excitation energy densities in atomic collision cascades. The model treats electronic friction as well as electron promotion as a source term of electronic energy that is carried away from the original point of excitation according to a nonlinear diffusion equation. While the frictional source is treated within the Lindhard model of electronic stopping, electron promotion is described using diabatic correlation curves derived from ab initio molecular orbital energy level calculations in combination with the Landau–Zener curve crossing model. Results calculated for two selected collision cascades show that the electron promotion mechanism may contribute significantly to the excitation energy density in the cascade volume, giving rise to distinct peaks of the local electron temperature at the surface. This contribution is essentially restricted to the first 100 fs after the projectile impact and may therefore be of significance for either external or internal kinetic electron emission. At later times, where the bombardment-induced particle kinetics lead to the sputter ejection of material from the surface, the excitation is shown to be primarily governed by electronic friction. This finding is important in light of excitation and ionization probabilities of sputtered particles.

Lasers in Periodontics: A Review of the Literature

Despite the large number of publications, there is still controversy among clinicians regarding the application of dental lasers to the treatment of chronic periodontitis. The purpose of this review is to analyze the peer-reviewed research literature to determine the state of the science concerning the application of lasers to common oral soft tissue problems, root surface detoxification, and the treatment of chronic periodontitis. A comprehensive computer-based search combined the following databases into one search: Medline, Current Contents, and the Cumulated Index of Nursing and Allied Health. This search also used key words. In addition, hand searches were done for several journals not cataloged in the databases, and the reference lists from published articles were checked. All articles were considered individually to eliminate non-peer-reviewed articles, those dealing with commercial laser technology, and those considered by the author to be purely opinion articles, leaving 278 possible articles. There is a considerable conflict in results for both laboratory studies and clinical trials, even when using the same laser wavelength. A meaningful comparison between various clinical studies or between laser and conventional therapy is difficult at best and likely impossible at the present. Reasons for this dilemma are several, such as different laser wavelengths; wide variations in laser parameters; insufficient reporting of parameters that, in turn, does not allow calculation of energy density; differences in experimental design, lack of proper controls, and differences in severity of disease and treatment protocols; and measurement of different clinical endpoints. Based on this review of the literature, there is a great need to develop an evidence-based approach to the use of lasers for the treatment of chronic periodontitis. Simply put, there is insufficient evidence to suggest that any specific wavelength of laser is superior to the traditional modalities of therapy. Current evidence does suggest that use of the Nd:YAG or Er:YAG wavelengths for treatment of chronic periodontitis may be equivalent to scaling and root planing (SRP) with respect to reduction in probing depth and subgingival bacterial populations. However, if gain in clinical attachment level is considered the gold standard for non-surgical periodontal therapy, then the evidence supporting laser-mediated periodontal treatment over traditional therapy is minimal at best. Lastly, there is limited evidence suggesting that lasers used in an adjunctive capacity to SRP may provide some additional benefit.

Equilibrium thermodynamics from basin-sampling

We present a "basin-sampling" approach for calculation of the potential energy density of states for classical statistical models. It combines a Wang-Landau-type uniform sampling of local minima and a novel approach for approximating the relative contributions from local minima in terms of the volumes of basins of attraction. We have employed basin-sampling to study phase changes in atomic clusters modeled by the Lennard-Jones potential and for ionic clusters. The approach proves to be efficient for systems involving broken ergodicity and has allowed us to calculate converged heat capacity curves for systems that could previously only be treated using the harmonic superposition approximation. Benchmarks are also provided by comparison with parallel tempering and Wang-Landau simulations, where these proved feasible.

3206 X線CTガントリーの構造シミュレーションと最適化(OS8 設計と最適化(II),未来社会を支えるものづくりとひとづくり(設計・システムから))

We obtained a high-rigidity and light-weight structure for an X-ray CT scanner gantry using topology and shape optimization methods. The optimization procedures were as follows. First we calculated the deformation caused by an imbalance of centrifugal forces and evaluated the strain energy density of the X-ray CT scanner gantry ; we focused on the stand through the calculation of the strain energy density. Then we determined the required stand stiffness satisfying the acceptable deformation that is the design specification to obtain high-quality tomograms. Finally, we optimized the stand under the constraint conditions for the stiffness. Thus, we confirmed that the optimized procedures have effectiveness for the X-ray CT scanner gantry design.

Stomach filling may mediate the influence of dietary energy density on the food intake of free-living humans

The energy density of the diet has been demonstrated to be a significant influence on the daily intakes of humans which has led to the hypothesis that intake control is based upon the weight and volume of food and not its energy content. The study explored the roles of the components used in the calculation of energy density and stomach filling in dietary energy density effects upon intake. Dietary energy density relationships with intake and body size were studied in 264 male and 406 female free-living adult humans who provided a detailed record of their eating and drinking in 7-day diaries. High energy density was associated with larger amounts of food energy and larger amounts of solids, but lower total weight of meals, daily intakes, and weekly intakes. The lower total weight occurred due to lower fluid intake in drinks. Multiple regression analysis revealed that overall dietary energy density was more important than the energy density of particular nutrients. Intake of fluids in drinks did not contribute to the relationship of dietary energy density with intake. The estimated weight of the contents of the stomach following the meals was relatively constant regardless of the energy density of the meals, daily, or weekly intakes. Energy density was not significantly related with body size, height, weight, or BMI. The findings support the notion that short-term intake is controlled on the basis of its weight and volume as opposed to its food energy content.

Electronic, optical and luminescent properties of PbFCl single crystal

The first-principles calculation of energy band structure and density of states of the PbFClcrystal based on the plane waves and pseudopotential method in the frame of thegeneralized gradient approximation (GGA) were performed. Further, calculation with theGW approximation was used to correct the bandgap. The so-calledGW approximation represents the lowest expansion of the self-energy,Σ, equal to the Greenfunction G times the screenedCoulomb interaction W. The calculated result shows that the direct bandgap is located at the Z pointin the Brillouin zone with the gap of 3.5 eV in the GGA frame and 5.0 eV afterGW correction. X-ray photoemission spectroscopy for the valence band (VB-XPS) was carriedout to compare with the calculated density of states in the valence band, suggesting thatthe calculated result is in agreement with the experimental result. The reflection,excitation and emission spectra were measured using a synchrotron radiation lightsource in the energy region of 4–9.5 eV. The absorption and emission of the cationexciton was observed at 5.0 and 3.8 eV, respectively. The components of Pb 6pstates and Pb 6s states located at the bottom of the conduction band and the topof the valence band, respectively, prove the possibility of the cation exciton ofPb2+.Violet band emission peaking at 3.1 eV was also observed, which may be due to the self-trapped excitonor the Pb2+ ion close to the Schottky-like defect.

Diet energy density and energy intake in palliative care cancer patients

Anorexia and cachexia are frequent in advanced cancer. Energy density may be important in the control of energy intake; however, current data are derived from studies in healthy or obese populations and there is no agreed definition and methods of calculation. We studied energy density and energy intake in a group of palliative cancer patients and explored which method of energy density calculation that yielded the highest determination coefficient of energy intake. Energy density was calculated from 259 food records using four methods, differing in the types of food and beverages included in the analysis. Association between energy density and energy intake was tested using regression analysis. The determination coefficient for total energy intake was: 0.181, 0.148, 0.222, and 0.211 for methods 1-4, respectively (P for all <0.001). In relation to energy per kg body weight and resting energy expenditure, methods 3 and 1 yielded the highest determination coefficient, R2 = 0.164 and 0.184, respectively. We found a positive association between diet energy density and energy intake. The method used when calculating energy density had limited impact on this association. When calculating energy density all food and beverages should be included in the analysis.

Dietary Energy Density Determined by Eight Calculation Methods in a Nationally Representative United States Population

Dietary energy density [kcal/g (kJ/g)] influences energy intake under controlled laboratory conditions. Little is known about the energy density of the diets of free-living persons. Because energy density investigations are a relatively new endeavor, there are neither standard calculation methods nor published nationally representative values. This paper examines the calculation of energy density based on systematic exclusion of beverage categories, presents data on variability, and compares values by sex, age, and race/ethnicity in a representative sample of U.S. adults. Mean daily dietary energy density values for adults (aged >19 y) were calculated using two 24-h recalls from the Continuing Survey of Food Intakes by Individuals 1994–1996 based on food, food and liquid meal replacements, food and alcohol, food and juice, food and milk, food and juice and milk, food and energy-containing beverages, and food and all beverages. Energy density varied by calculation method, ranging from 0.94 to 1.85 kcal/g (3.93–7.74 kJ/g). Intraindividual-to-interindividual CV ratios were highest for the food and energy-containing beverages calculation. Men reported diets with a higher energy density than women for all calculation methods (P < 0.0001). There were differences by race/ethnicity and an inverse linear trend for age. These data indicate that beverage inclusion schemes should be clearly defined when reporting energy density values. In epidemiologic studies, calculations based on food and all beverages and food and energy-containing beverages may diminish associations with outcome variables. These nationally representative data, which provide an important frame of reference for other studies, indicate that dietary energy density differs by sex, age, and race/ethnicity.

炭酸ガスレーザー照射によるラットけい骨の骨形成促進に関する研究

Low Level Laser Therapy (LLLT) using CO2 lasers is known to activate surrounding cells and tissue. However, few studies concerning LLLT using hard lasers have been perform, and much about the biological mechanism of LLLT. In the present study, we report morphological changes in rat tibiae irradiated by CO2 laser without surgical treatment. The purpose of this study was to histologically evaluate the effects of LLLT using a CO2 laser on bone formation in rat tibiae. The left tibiae underwent CO2 laser irradiation, while the right tibia did not undergo CO2 laser irradiatio (Control). Rat tibiae were irradiated by CO2 laser from the outside of the body.Irradiation was performed at the following power and exposure time: power, LOW; duration: 15 min; calculated energy density, -1.1KJ/cm2. On the 7th day after irradiation, tibiae were removed and were analyzed by Soft X-ray. Serial sections were prepared for osteoid staining (Yoshiki's method) and ALP (Alkalinephosphatase) staining, and were examined for mineralized apposition rate (Calcein labeling). Soft X-ray examination revealed no differences between the control and CO2 laser-irradiated groups. However, marked osteoid formation (Yoshiki's method) on the surface of laser-irradiated tibiae and young ALP-positive osteoblasts were present in the osteoid tissue. Interestingly, calcein labeling demonstrated that mineral apposition rate on the periosteum of laser-irradiated cortical bone was much higher than that in control tibia. These results demonstrate that LLLT using CO2 laser induced not only mineralization but also osteoblast differentiation. The present study suggests that CO2 laser can be applied to bone regeneration treatment. (J. Jpn. Soc. Laser Dent. 16: 23-30, 2005 Reprint request to Dr. YOKOSE) Key words=LLLT, Bone regeneration, CO2 laser

Magnetic anisotropy of FeGa alloys

Cubic magnetocrystalline anisotropy constants, K1 and K2, for Fe1−xGax alloys were measured using magnetization curves with x=0.05, 0.125, 0.14, 0.18, and 0.20. Thin circular (110) disks all with 〈100〉, 〈110〉, and 〈111〉 in the plane of the disk were used to measure K1 and K2. K1 was also measured with (100) circular disks. K1 for 5 at. % Ga content was found to be larger than that of pure Fe. (All compositions mentioned hereafter are atomic percents.) K1 and K2 both drop gradually up to 18 at. % Ga substitution. Then there is a sharp drop in the magnitude of both constants. K2 was found to be equal to −9K1/4 and the 〈110〉 and 〈111〉 directions were equally hard magnetically for all compositions considered in this study. Calculation of the anisotropy energy density verifies this result. K1 measured from both (110) and (100) disks was reasonably consistent.

Destruction of 1,1,1-Trichloroethane Using Dielectric Barrier Discharge Nonthermal Plasma

This study investigates the feasibility of using nonthermal plasma produced in a dielectric barrier discharge reactor to destroy 1,1,1-trichloroethane ~TCA! in a stream of air. The effects of various operating parameters on the destruction and removal efficiency ~DRE! of TCA were examined. The experiments indicated that the water vapor concentration greatly influenced the destruction of TCA and the relative amount of oxidation by-products. DRE as high as 99.9% could be achieved at very low relative humidity ~RH! conditions. Analysis of the CO/CO2 concentrations in the reactor effluent indicated a decrease in the amount of CO generated as the RH was increased. The lowest CO/CO2 ratio, 1:3, was observed at 88% RH. The estimated cost and energy requirement for operation were also determined. The calculated energy density values ~b! varied with respect to the RH, and ranged from 1,478 to 3,010 J/L over a RH range of 0- 88%.

Dietary Energy Density Is Associated with Increased Intake in Free-Living Humans

Dietary energy density markedly influences the daily dietary intake of humans. The present study examined the relation of energy density to dietary intake and body size in 371 male and 581 female adults. The subjects were free-living and provided a detailed record of their everyday food and drink intake in 7-d food diaries. The reported diets were analyzed for the relation of energy density to body size and to per-meal, daily, and weekly dietary intake. High energy density was associated with greater (P < 0.001) total intake, especially of fat, when intake was correlated with energy density (r = 0.26, P < 0.001) and when the daily intake of individual participants was correlated with their daily dietary density (r = 0.66, P < 0.001). These results occurred regardless of sex, low reporting, or the inclusion of drinks in the energy density calculations. High energy density was also associated with a high rate of intake (r = 0.46, P < 0.001) and large meal sizes (r = 0.61, P < 0.001). However, energy density was not correlated with body size, height, weight, or body mass index. High energy density appears to be related to greater overall intake in the short-term, but there may be compensation over the long term, with no net effect on body size.

A local energy density methodology for monitoring the evolution of gear faults

A new method for monitoring the evolution of gear faults based on the calculation of local energy density is presented. A theoretical model for a gear pair with a tooth root crack was developed. Experimental results from a test rig were analyzed using the continuous wavelet transform and the energy density of the vibration signal associated with the meshing of defected gears was calculated. It was shown that the local energy is a sensitive feature for assessing the fault magnitude. An empirical law, which relates the energy content to the depth of the crack, was established.

J1432+158: the most distant giant quasar

We present low-frequency, Giant Metrewave Radio Telescope (GMRT) observations at 333 and 617 MHz of the most distant giant quasar, J1432+158, which is at a redshift of 1.005. The radio source has a total angular extent of 168 arcsec, corresponding to a projected linear size of 1.35 Mpc. This makes it presently the largest single object observed beyond a redshift of 1. The objectives of the GMRT observations were to investigate the possibility of detecting a bridge of emission at low frequencies, which may be suppressed due to inverse-Compton losses against the cosmic microwave background radiation. We detect a jet-like structure connecting the core to the western hotspot, while the eastern hotspot is found to be largely tailless with no significant bridge emission. The estimated lifetime for the radiating electrons in the tail of the western lobe appears smaller than the travel time of the radiating particles from the hotspot, suggesting either in situ acceleration or dissipation of energy by the jet at this location. The pressure of the intergalactic medium at z ∼ 1 estimated from the minimum energy density calculations appears to be marginally lower than the value extrapolated from nearby giant radio galaxies.

Equation of state for two flavor QCD at nonzero chemical potential

We present results of a simulation of QCD on a 4x16^3 lattice with 2 continuum flavors of p4-improved staggered fermion with mass m/T=0.4. Derivatives of the thermodynamic grand potential with respect to quark chemical potential mu_q up to fourth order are calculated, enabling estimates of the pressure, quark number density and associated susceptibilities as functions of mu_q via Taylor series expansion. Discretisation effects associated with various staggered fermion formulations are discussed in some detail. In addition it is possible to estimate the radius of convergence of the expansion as a function of temperature. We also discuss the calculation of energy and entropy densities which are defined via mixed derivatives of the thermodynamic grand potential with respect to the bare couplings and quark masses.

Ab initio calculation of intrinsic point defects in CuInSe 2

Preliminary ab initio calculation of different point defects energy and electronic density of states have been performed on the prototype chalcopyrite semiconductor CuInSe 2. The simulation method used is based on the density functional theory within the framework of pseudo-potentials and plane waves basis. The isolated neutral defects considered are: V Cu, V In, V Se, Cu i , In i , In Cu, Cu In and the complex defects are 2Cu i +Cu In, In Cu+Cu In and 2V Cu+In Cu, some of which being computed for the first time by advanced ab initio techniques. In agreement with previous results, we show that some point defects (such as V Cu) and pair defects (2V Cu+In Cu) have very low formation energies. Some energies of formation were found significantly lower than previous estimations. The comparison of the formation energies with the exchange correlation (LDA or GGA) is discussed. The perturbation induced by the presence of some of these ideal defects on the density of states is also presented.

Three-volt lithium-ion battery with Li[Ni 1/2Mn 3/2]O 4 and the zero-strain insertion material of Li[Li 1/3Ti 5/3]O 4

A 3 V lithium-ion cell with Li[Ni 1/2Mn 3/2]O 4 ( Fd 3 ̄ m ; a=8.17 Å) and the zero-strain insertion material of Li[Li 1/3Ti 5/3]O 4 ( Fd 3 ̄ m ; a=8.36 Å) was examined with an emphasis on rate-capability and cycle life. This cell showed a quite flat operating voltage of 3.2 V with excellent cycleability. Accelerated cycle tests indicated that 83% of the initial capacity was delivered and stored even after 1100 cycles. Although the calculated energy density of a Li[Li 1/3Ti 5/3]O 4/Li[Ni 1/2Mn 3/2]O 4 cell was about 250 Wh kg −1 or 1000 Wh dm −3 based on the active material weight or volume, the 3 V lithium-ion battery exhibited positive characteristic features, such as flatness in operating voltage, high rate capability, and cycle life.

Metrology system for pulsed electric fields processing

Efficient process monitoring and accurate measurement of the electrical parameters defining pulsed electric fields (PEF) treatment and lethality are key factors in the implementation of PEF. A metrology system that can accurately evaluate and record treatment delivery was developed. To achieve this end one current sensor and two high voltage sensors were placed in a food PEF coaxial treatment chamber, grounded and shielded to minimize noise pick up due to electromagnetic interference, and connected to a digital oscilloscope to register PEF pulses. A graphical computer program was developed to control the oscilloscope and conduct data acquisition, measurement, and keep a data record of the electrical parameters defining the process: peak current, peak voltage, electric field, pulse width, and energy delivered. The program allows real-time calculation of the electrical parameters and reports all measurements with their uncertainties, which were evaluated with an uncertainty propagation analysis of the whole system. The metrology system was tested during PEF processing of a saline solution (σ=0.47 S/m at 20 °C) using a pilot plant pulse generator. The relative uncertainties reported range from 1.3 to 13.5%. The experimental results showed good agreement when compared with those simulated by PSpice™ software. Also, the calculated energy density applied to the saline solution correlated to its temperature rise, within 1 °C. The methodology followed in this research and the metrology system developed can be extrapolated and implemented in industrial scale PEF systems to monitor and keep data records of the PEF process.