Efficiency Of Energy Deposition Research Articles

Surface-induced dissociation of diphenyl ether

The primary fragmentation of diphenyl ether and further secondary dissociation of its fragments have been studied by surface-induced dissociation (SID). In a tandem linear time-of-flight mass spectrometer, the dissociation of ions is studied as a function of the collision energy with a liquid perfluorinated polyether (PFPE) surface. In a tandem quadrupole instrument, an alkyl terminated (C 18) and a perfluoroalkyl terminated (FC 10) self-assembled monolayer surface have been used. The differences in the spectra obtained with the TOF and quadrupole instruments are attributed to the different time frames available for observation of the fragments. Deconvolution of the collision energy resolved SID spectra of diphenyl ether shows that above 50 eV collision energy, the energy deposition efficiency is similar in the two experimental set-ups, in spite of the different geometries. Ion/surface reactions are observed upon collisions of the diphenyl ether radical cation with the C 18 surface but not with the FC 10 surface The rearrangement fragments, obtained from perdeuterated diphenyl ether, C 11D 10 + and C 11D 9 +, react with both the C 18 and FC 10 surface. Hydrogen exchange with the surface combined with hydrocarbon loss from C 12D 10O +, C 11D 10 +, and C 11D 9 + is observed.

Amorphous track formation in SiO 2

Amorphous track formation is analyzed in SiO 2 α-quartz according to a thermal spike model. As predicted by the model, for tracks with R e > 4.5 nm R e 2 ∼ S e ( R e — the effective track radius, S e — the electronic stopping power) fulfils for α-SiO 2. The efficiency of energy deposition is g = 0.36 for low velocity ion bombardment in excellent agreement with that in yttrium iron garnet and lithium niobate. The high efficiency is the consequence of the effect of the ion velocity on the damage cross section. Tracks with R e < 4.5 nm exhibit an ambiguity that can be resolved only by new experiments. The consequences of the variation of the spatial width of the electron energy distribution with the ion velocity are discussed.

GHz ultrasonic measurement using a transient reflecting grating method under a surface plasmon resonance condition

A transient holographic pattern, which is called a transient reflecting grating (TRG), is produced on a solid surface when two pulsed lights are simultaneously irradiated at the same spot of a small size. By using a probe light delayed relative to the above excitation pulses, a time profile of the TRG is observed by changing the delay time of the probe pulse. The signal waveform includes information about generation and relaxation of ultrasonics and heat. Using this technique, a few-GHz ultrasonics were observed for a wide variation of material surfaces [A. Harata et al., Trends Anal. Chem. 14, 504–511 (1995)]. In this report highly sensitive detection of the TRGs utilizing surface plasmon resonance (SPR) is described. Energy deposition efficiency from light into heat was very effective under an SPR condition and the energy absorbed by a surface plasmon polariton (SPP) is concentrated on the solid surface. Utilizing an arrangement of total internal reflection for the SPP excitation, a TRG method about ten times more sensitive could be realized. A new type of SPR-enhanced TRG method is also proposed where the probe beam excites SPPs. The method made it possible to separate ultrasonics and the heat contribution to the TRG signal.

Separate and combined effects of ephedrine and caffeine on protein and lipid deposition in finishing pigs

AbstractTwo experiments were conducted to examine the effects of dietary inclusion of an ephedrine (Eph)/caffeine (Caf) mixture on finishing (55 to 100 kg live weight) castrated male pigs. The first experiment was conducted as a dose-response study and showed that the mixture had an optimal effect on performance and carcass composition at a dietary inclusion level of approximately 56/560 mg/kg of Eph and Caf, respectively. In the second experiment, interactions between the compounds were studied by dietary inclusion of Eph (56 mg/kg) and Caf (560 mg/kg) separately or as a mixture (56/560 mg/kg). The mixture reduced food intake by 0·12 and improved the food: gain ratio by 0·08. Muscle protein deposition rate was increased proportionately by 0·25, lipid accretion rate was decreased proportionately by 0·27, and gross energetic efficiency of energy deposition decreased proportionately by 0·09. This resulted in a changed proportional carcass composition towards more muscle (0·08) and less fat (0·21) after treatment with the mixture. The reduction in food intake was sustained due to an interaction over the first 3 weeks of treatment changing to additive effects by the compounds. The increased muscle protein deposition rate after feeding the mixture was entirely due to Eph, while the decreased gross energetic efficiency of energy deposition was caused by Caf. On the other hand, both compounds contributed almost equally to the decrease in lipid accretion rate. These results show that an Eph/Caf mixture markedly improves performance and body composition in finishing castrated pigs.

Efficiency of energy deposition in lasers pumped by uranium fission fragments

An investigation was made of the efficiency of energy deposition by fission fragments in nuclear-pumped lasers. A comparison was made with results obtained by other authors. Possible reasons for the discrepancy between the experiment and theory were analysed.

2 MeV As + implantation in InAs

High energy ion implantation of 2 MeV As + ions into 〈100〉 InAs was investigated using Rutherford backscattering spectrometry with 2 MeV He + ions. The ion fluence N 1 varied over a wide range between 2 × 10 12 cm −2 and 5 × 10 16 cm −2. The relative defect concentration n pd( z), calculated from the backscattering spectra with the help of the computer code DICADA2, is compared to the distribution of the electronic and the nuclear energy density obtained from TRIM simulations. It is found that the defect mobility and the defect annealing during room temperature implantation are strongly influenced by the total energy density deposited into electronic processes. A similar behaviour is found for GaAs but not for InP. We believe that in the arsenides the energy deposition into electronic processes reduces the efficiency of the nuclear energy deposition for producing stable defects.

'Squirrel-cage'-an effective configuration of REB injection

An effective system of REB injection has been proposed. The cylindrical N-pole magnetic wall formed by N conductors performs effective trapping of REB electrons of N band beams injected through the N cusps of multipole magnetic field. The proposed scheme of REB injection allows one to minimize beam losses and to reach a high efficiency of energy deposition into gas up to 90%. The desirable shape of beam energy deposition and plasma distribution can be realized by changing the number of magnetic poles and the value of magnetic field. The model of an effective source of argon plasma has been represented by using the Monte Carlo method in combination with a plasma kinetics simulation.

An application of minimax robust optimal control theory for selective vibrational excitation in molecules

In recent investigations control theory was applied to design electromagnetic fields capable of producing vibrational excitation in molecular systems. This approach has been applied to linear or non-linear classical approximations of molecular systems or to quantal systems using distributed cost functionals. Practical computations of molecular optimal control theory for large molecules especially with anharmonic potentials become difficult due to the increased dimensionality and the mixed nature of the boundary conditions. This paper proposes to approach the control design for such systems by treating a portion of the molecule containing the target and dipole bonds in full detail while the effect of the remainder of the system is modelled as a disturbance of limited energy. The optimal fieldminimizes the cost functional which is simultaneouslymaximized with respect to the disturbance. Such assumptions give rise to a robust controller akin to theH∞ theory of robust estimation. We investigate the various field designs for truncated harmonic systems associated with different disturbance energies and demonstrate that the existence of the solution to the associated Ricatti equation ensures the existence of the equilibrium game point. In addition, in the range of physically reasonable disturbance energy the optimal field could be accurately predicted from an asymptotic expansion involving only the undisturbed reference case. As an application we show the optimal field design for a 20 atom truncated molecular chain containing both the target bond (the 5th bond) and the dipole bonds (1st and 9th) where the disturbance only affects the end bond of the system attached to the remainder of the chain. In an effort to improve on the efficiency of the bond energy deposition we investigate shortened target times and also a 40 atom truncated chain. This approach presents very conservative estimates of possible disturbances but provides insight into the sensitivity of different configurations with respect to external disturbances. The minimax approach can be generalized to non-linear molecular systems by modelling the original system as a linear system plus an energy constrained disturbance.

Influence of the chemical composition of the hydrogen-containing component in an RH active medium and of the initiation method on the parameters of a pulsed chemical SF6–RH laser

The influence of the composition of the active medium on the lasing characteristics and energy deposition efficiency was studied under conditions of electron-beam and electric-discharge initiation in SF6–H2 and SF6–HI pulsed hydrogen fluoride chemical lasers.The best radiation energy characteristics were achieved for an SF6–HI active medium using electron-beam initiation and for an SF6–H2 active medium when the pump reaction was initiated by a self-sustained volume discharge. The following pulse parameters were obtained for an SF6–HI laser:energy 1.5 J, half-height pulse duration 60 ns,and leading edge duration 20 ns.

Numerical Investigations of Electron Beam Energy Deposition into the Gas Medium of an Excimer Laser

Electron beam propagation in a dense gas medium is numerically investigated. All the main phenomena that determine electron beam behavior in a gas (scattering and energy losses of the electrons on the gas atom molecules, ionization and excitation, electron thermalization, beam pinching, and influence of a magnetic guide field) are taken into account. The initial beam energy and the gas chamber dimensions are varied in a wide range: typical gas mixtures for the excimer lasers are considered. Graphs are given that allow the choice of the optimal electron beam energy that provides the maximum efficiency of the beam energy deposition into the gas, depending on the gas chamber dimensions.

Effect of fatty acid composition of dietary fat on energy balance and expenditure in hamsters

The comparative effects of feeding diets containing corn, olive, coconut, or menhaden fish oil on efficiency of energy deposition and on short term energy expenditure were examined in growing hamsters. Diets comprising oils mixed with laboratory diets at 10% oil w/w were fed ad libitum for 3 weeks. Animals fed laboratory diets were used as controls. Body composition was determined before and after the feeding period using 3H2O distribution space. Oxygen consumption was measured in each animal during the final week. Weight gains of groups fed corn and olive oil diets exceeded those of the group fed laboratory diet alone (p less than 0.05), although metabolizable energy intakes were similar across groups. Corn oil fed animals demonstrated higher carcass energy gains as fat compared with laboratory diet fed or menhaden oil fed groups. This was reflected in an increased fractional deposition of metabolizable energy intake in the group fed corn oil diet compared with the latter two groups. Fecal energy losses were lower in the group fed corn oil diet, and higher in the group fed laboratory diet alone, compared with other groups. Oxygen consumption did not differ between groups. These findings indicate that feeding dietary fish oil, compared with corn oil, favours energy substrate oxidation reducing the fraction of metabolizable energy partitioned for storage.

Common envelope evolution of binary stars

We discuss the common envelope phase in the evolution of binary systems. The problem of the efficiency of energy deposition into envelope ejection is treated in some detail. We describe the implications of common envelope evolution for the shaping of planetary nebulae with close binary nuclei and for double white dwarf systems, considered to be the progenitors of Type I supernovae.

Common Envelope Evolution of Binary Stars

AbstractWe discuss the common envelope phase in the evolution of binary systems. The problem of the efficiency of energy deposition into envelope ejection is treated in some detail. We describe the implications of common envelope evolution for the shaping of planetary nebulae with close binary nuclei and for double white dwarf systems, considered to be the progenitors of Type I supernovae.

The common envelope phase in the evolution of binary stars

The common envelope phase in the evolution of binary systems is examined. Three parameters are identified which characterize the efficiency of energy deposition, the importance of three-dimensional effects, and the efficiency of spin-up of the envelope. It is demonstrated that the efficiency of deposition of orbital energy into envelope ejection can be quite low. It is found that significant spin-up of the envelope can be expected to occur in relatively early stages, when the spiralling-in occurs inside evolved supergiant envelopes. In normal giants spin-up can occur only in the final stages of the spiralling-in process. The results of a simplified three-dimensional numerical calculation of the common envelope phase are presented, and the implications of the results for the formation of planetary nebulae with binary nuclei, double white dwarf systems, and FK Com stars are discussed. 52 references.

Prevention of genetic fa/fa obesity with an ephedrine-methylxanthines thermogenic mixture.

A thermogenic mixture containing ephedrine and methylxanthines was administered to 8-wk-old genetically obese fa/fa rats (O-E/Mx group) for a period of 15 wk. Their energy balance and the final body composition were compared with an untreated ad libitum-fed (O-AL) group, as well as to other fa/fa obese animals that were either pair fed to lean controls (O-PF group), or that were food restricted to such an extent they maintained a similar body weight to that of lean animals (O-WF group). Energy intake was elevated above lean or O-PF levels by approximately 27 and 10% in the O-AL and O-E/Mx groups, respectively, but lower by 18% in the O-WF group. Energy expenditure, compared with the lean values, was 10% higher in both the O-AL and O-E/Mx groups, but reduced by 13 and 30% in the O-PF and O-WF groups, respectively. The gain in body energy and the efficiency of energy deposition remained elevated above the lean values by 2.3- to 3.5-fold in the O-AL, O-PF, and O-WF groups but were reduced to lean levels in the O-E/Mx groups. These studies indicate that, unlike food restriction, the ephedrine-methylxanthine mixture prevents or arrests the development of the obesity in the fa/fa mutant by normalizing their energetic efficiency to that of the lean.

Excitation and damping of compressional hydromagnetic waves on a magnetized, high-pressure plasma column

Azimuthally symmetric (m=0) radio-frequency (rf) waves for zero and for finite axial wavenumber k are investigated in a low-compression linear theta pinch. The (k=0) modes occur spontaneously following the implosion phase of the discharge. For the k≠0 modes, a novel 100 MW, 1 MHz current drive is used to excite the plasma column in the vicinity of the lowest fast magnetoacoustic mode at various filling pressures. Phases, amplitudes, and radial mode structure are studied for both the k=0 modes and the externally driven (k≠0) modes. In the first case, the damping is determined from the e-folding time of the decaying oscillations. In the latter case, the phases and amplitudes indicate a broad resonance structure, from which we extract the damping constant. The energy deposition of the externally driven rf wave leads to a radial expansion of the plasma column, as observed by axial interferometry and by excluded flux measurements. These experimental results are compared with the predictions of two MHD-like ion-kinetic models. The characteristic and resonant frequencies, as well as the oscillatory radial mode structure, can be understood within the ideal MHD description. It is found that the viscous kinetic model overestimates the observed k=0 damping by at least an order of magnitude, while both this and the ion Landau-damping model (with and without ion-cyclotron effects) underestimate the (k≠0) damping by at least an order of magnitude. The experimentally observed damping and wave-energy deposition are consistent with the magnitude of the rf oscillations. The efficiency of the rf energy deposition is at least 27%.

Thermal conditions in a self-heated copper vapor laser and its stimulated emission characteristics

An investigation was made of the efficiency of the deposition of energy in a plasma of a pulse discharge pumping a copper vapor laser operating under self-heating conditions. It was found that the efficiency of energy deposition reached 50–70% when a thyratron power supply system was used. An analysis was made of the characteristics of stimulated emission on the energy characteristics of the excitation under various operating conditions.

Maintenance energy requirement in pregnant rats and net energetic efficiency for fetal growth during late pregnancy.

The maintenance energy requirement (MEm) of pregnant rats and net energetic efficiency for fetal growth during late pregnancy were examined by regression analysis. Pregnant rats, weighing about 180 g, were fed on 20% casein diet during early-mid pregnancy and then divided into three groups--ad libitum-fed, 50% food restricted, or starved. A linear relation between the energy balance (Y, kcal/100 g BW/day) and the metabolizable energy intake (X, kcal/100 g BW/day) was obtained as Y = 0.81 X-14.83 (n: 17, r = +0.99, p less than 0.001). The X-intercept, MEm, was calculated to be 18.31 kcal/100 g BW/day. Pregnant animals fed ad libitum retained 6.1 and 1.1 kcal of energy daily in their conceptuses and their own body, respectively, during late pregnancy. Assuming that the net efficiency of maternal energy deposition is equal to that for size- and age-matched nonpregnant rats, the net energetic efficiency for fetal growth was calculated to be 82%. This value was very close to the net efficiency for weanling rats reported previously, suggesting that the net energetic efficiency for maximum growth in well-nourished rats is about 82%.

Studies on the energy metabolism of the pregnant sow. 2. The partition and utilization of metabolizable energy intake in pregnant and non-pregnant animals.

The heat losses and energy and nitrogen balances of pregnant gilts, and of their non-pregnant litter sisters (controls), were measured for periods of 7 d at feed intakes of 1.8 or 2.5 kg/d (20 or 30 MJ metabolizable energy (ME) respectively) at an environmental temperature of 20 degrees. The measurements were made within three separate periods of gestation; 40-60 d (early), 60-80 d (mid) and 90-110 d (late). Values for ME intake, heat loss, energy retention (ER), protein deposition and fat deposition were determined for both the pregnant and control animals on each treatment. When expressed per kg body-weight0.75 per d, there was little difference in heat loss between pregnant and non-pregnant animals and between pregnant animals at the different stages of gestation at any given ME intake. However, heat loss was higher at the higher ME intake. ER varied inversely with heat loss. The decrease in ME intake (kJ/kg body-weight0.75 per d) during pregnancy resulted in a decrease in ER so that the pregnant animals were in negative energy balance at the low feed intake during late gestation. From the relation between ER and ME intake, estimates of the maintenance energy requirement (MEm) of 411 and 401 kJ/kg body-weight0.75 per d were calculated, with corresponding partial efficiencies of energy utilization (k) of 0.74 and 0.68 for the pregnant and non-pregnant animals respectively. For the pregnant animals, protein deposition was highest during mid-pregnancy and was relatively independent of level of feeding during mid- and late pregnancy. There was little difference in protein deposition between pregnant and non-pregnant animals at the high feed intake. At the low feed intake, the pregnant animals generally had a higher protein deposition than their non-pregnant litter sisters and this was entirely associated with the accretion in reproductive tissue. Fat deposition depended on the level of feeding, and at any given ME intake was similar for pregnant and control animals. In late gestation the low level of feeding was insufficient to prevent the pregnant animals losing fat. It was calculated that at term these animals lost 140 g fat/d from maternal stores. From the relation between ME intake and protein and fat deposition, estimates of MEm and the energetic efficiencies of protein (kp) and fat (kf) deposition were determined. There was little difference in MEm (422 and 420 kJ/kg body-weight 0.75 per d) and kf (0.88 and 0.90) between pregnant and non-pregnant animals respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Heating of metals by nanosecond XeCI* laser radiation pulses generating a surface plasma

An investigation was made of the interaction of metals in air with ultraviolet radiation of the wavelength 308 nm and intensity up to 3×109 W/cm2. The plasma formation threshold was found to depend strongly on the degree of laser cleaning and preliminary preparation of the target surfaces. The target material had a decisive influence on the dependence of the efficiency of energy deposition on the laser radiation intensity. Conditions for low-threshold breakdown of air by ultraviolet laser radiation were analyzed.