Intergrain scattering in polycrystals

Cross sections for attachment of thermal and near-thermal energy electrons to nine aromatic hydrocarbons are reported. The attachment cross sections peak sharply at zero energy and vary inversely with the electron velocity at thermal energies. The thermal attachment cross sections are discussed in relation to the energy of the first excited π-singlet state and the electron affinity.

Thermoplastic starch (TPS) materials have great potential to replace some conventional synthetic plastics, and have the advantage of being economical, biodegradable, renewable, and can usually be processed using conventional plastic processing equipment. An important requirement is that TPS materials should have acceptable mechanical and biodegradability properties as a given functional material. The structure of TPS materials, at the molecular, crystalline and granular levels, may be altered during processing, which in turn affect their mechanical properties and biodegradability. This dissertation encompasses a detailed understanding of starch structural changes resulting from an archetypal processing procedure, and also examines its effects on mechanical properties and biodegradability. The effects of the thermal and mechanical energies of extrusion on the starch degradation at multiple structural levels were quantitatively investigated. Waxy (WMS), normal (NMS), and high-amylose maize starch (HAMS) with different amylose contents of 0, 34 and 63%, were extruded with varying temperatures, screw speeds, and plasticizer contents. The size distributions of individual branches did not show any significant change after extrusion. The whole amylopectin molecules were degraded into smaller sizes during extrusion while whole amylose molecules were not significantly affected. The crystalline and granular structures were disrupted during extrusion, without changing the crystalline polymorph displayed, suggesting that the crystalline structure remaining mainly originated from ungelatinized starch, which was confirmed by polarized light microscope images. Starch structural degradation was more severe at lower plasticizer content due to the greater amount of mechanical energy input at the same screw speed. Higher processing temperature (thermal energy) did not have any significant effect on the crystalline structure. The effects of mechanical and thermal energies on starch structural degradation were analyzed separately using Pearson correlation tests to compare the effect of the different parameters, showing that mechanical energy caused more significant degradation on starch structure than thermal energy. The starch extrudates obtained previously were compression-molded and the crystalline structure of NMS films was further altered using a hydrothermal treatment (HTT). The mechanical properties of starch films with various molecular and crystalline structures were investigated. For WMS, which contains only amylopectin, the degradation at the molecular level did not affect the mechanical properties significantly. HAMS films, with a higher amylose content and longer branches, showed higher elongation at break, and tensile strength than WMS and NMS films. The effects of amylose content on the mechanical properties were not significant when the plasticizer content was low, probably because the starch chains were restrained in a more rigid network. As distinct from previous studies reporting that an increase in crystallinity enhanced some mechanical properties, the present study found that the crystallinity of different films prior HTT was not significantly correlated with their mechanical properties, which might be due to these crystalline structure from the remaining ungelatinized starch granules unable to form a continuous network. On the other hand, the alteration of TPS crystalline structure by HTT increased the tensile strength and Young’s modulus, while decreased the elongation at break. The results indicate that the crystallinity from the remaining ungelatinized starch granules has less significant effects on the mechanical properties of TPS than the crystalline structure formed from starch retrogradation, probably due to the leached-out amylose forming a stronger network surrounding the remaining starch granules. The effects of starch structures on the biodegradability of TPS films were investigated by hydrolyzing starch films using fungal α-amylase. The substrates comprised varied starch structures obtained by different degrees of acid hydrolysis, different granular sizes using size fractionation, and different degrees of crystallinity by aging for different times (up to 14 days). Two stages are identified for unretrograded films by fitting degradation data using first-order kinetics. Starch films containing larger molecules were degraded faster, but the rate coefficient was independent of the granule size. Retrograded films were degraded much slower than unretrograded ones, with a similar rate coefficient to that in the second stage of unretrograded films. Although initially the smaller molecules or the easily accessible starch chains on the amorphous film surface were degraded faster, the more ordered structure (resistant starch) formed from retrogradation, either before or during enzymatic degradation, strongly inhibits film biodegradation. Starch structural changes induced by processing at different levels can be inter-related with one another; for example, amylopectin molecules present in the rigid semi-crystalline conformation in native starch granules undergo severe shear scission by mechanical energy during extrusion, decreasing the degree of crystallinity and destroying the granular structure. Crystalline structure from the continuous network in TPS materials is dominant in improving the mechanical properties and decreasing the degradation rate of TPS. Although the molecular size does not influence the mechanical properties, it has a great impact on the biodegradability of starch films.

Approximately 60% of wasted heat originating from various sources, for example, electric power plants, factories, automobiles, and so on, is unused. Also there is a huge amount of unused, ambient heat around us. Therefore, thermoelectric (TE) power generation, which is a technology for directly recovering electric energy from unused, waste and ambient heat, has been drawing attention in recent years as next-generation energy.The combined use of thermal and photon energies has led to a new research topic based on the changes in the TE properties, i.e., Seebeck coefficient (S) and electrical conductivity (σ), under light irradiation. Two different phenomena are involved in this change. The first is the temperature gradient caused by thermal energy. The other is the contribution of photon energy of light called the photo-TE effect. In our previous research, platinum (Pt)-dispersed tungsten trioxide (WO3) thin film (Pt- WO3) after photochromic (PC) and/or gaschromic (GC) reaction (Pt-dispersed protonated WO3, Pt- dispersed HyWO3)) showed an n-type anomalous photo-TE effect where both S and s increased when irradiated with visible light in a nitrogen (N2) and formate (HCOOH) atmosphere [1]. The anomalous photo-TE effect was caused by the accumulation of electrons in Pt induced by the charge transfer from HyWO3 to Pt. In this study, we prepared Pt oxide and WO3 layered thin films (PtOx/WO3) and attempted to develop the anomalous photo-thermoelectric (photo-TE) effect for both n-type and p-type by controlling the thickness of PtOx.WO3 thin films were prepared on SiO2 substrate plates by a spin-coating using tungsten (VI) chloride as a tungsten source, being dissolved in ethanol, followed by drying on a hot plate. Then the spin-coated films were calcined in air at 500oC to form WO3 thin films. The thickness of the WO3 films was controlled to 650 nm. Pt species was deposited on the WO3 thin films, SiO2 substrates, and Si wafers by sputtering a Pt target under an argon atmosphere at room temperature. As discussed later, the deposited Pt species was a mixture of Pt and PtOx, which is referred to as PTO hereinafter. The thickness of PTO film was controlled at 50, 70, 90, 200 and 250 nm. The composition of the PTO were measured by X-ray photoelectron spectroscopy (XPS) on the surface and the inner region from the surface subjected in situ Ar+ etching of the PTO/WO3. PTO (50, 70, 90, 200, 250 nm) /WO3 that had been subjected to the GC reaction under a N2 flow containing HCOOH for 1 h was used for measuring the photo-TE effect. Here, HCOOH acted as a proton source and contributed to the GC reaction.Photo-TE properties (σ photo, S photo) were measured under visible light irradiation generated from a Xe lamp equipped with an optical filter (Y-52, > 500 nm). The same measurement was performed in the dark after the light irradiation. The measurements under these conditions were repeated several times to confirm the reproducibility of the σ photo and S photo data. At this time, HCHO was used instead of HCOOH to avoid the GC reaction during the measurement. In contrast to n-type conduction in PTO/Si, p-type conduction was confirmed in PTO/SiO2. The p-type conduction of PTO on SiO2 was explained by the formation of PtOx (PtO and PtO2) near the interface between PTO and SiO2. In fact, it was already reported that PtOx has the p-type characteristics [2,3]. In both cases, σ photo increased and the absolute value of S photo decreased, which we call the normal photo-TE effect. In contrast, in the cases of PTO (50, 90, 200, 250 nm)/WO3 (in fact, HyWO3), both the σ photo and S photo increased, indicating the anomalous photo-TE effect. On top of that, PTO (90, 200, 250 nm)/WO3 (HyWO3) indicated the p-type anomalous photo-TE effect, whereas PTO (50 nm)/WO3 (HyWO3) n-type anomalous photo-TE effect. We considered that the directions of photo excited electron transfer from PTO to H y WO3 and from H y WO3 to PTO are responsible for p- and n-type, respectively, of the anomalous photo-TE effect. A detailed study will be discussed at the meeting.References H. Irie et al., J. Appl. Phys., 119, 245109(2016).Fryer et al., J. Alloys Compd., 682, 216(2016).McBride et al., J. Appl. Phys., 69, 1596(1991).

The thermal emission rates of electrons and holes at gold−acceptor levels in silicon have been measured in P+N junctions as a function of temperature using the dark−current transient method. From these measurements the linearly extrapolated absolute zero thermal activation energies of electrons (553 meV) and holes (641 meV) have been determined taking the temperature dependence of the hole capture rate into account. The latter has been determined by measuring the diffusion length at different temperatures. Using earlier optical results which showed that the energy distance of the gold−acceptor center from the conduction band is independent of temperature, the thermal activation energies of electrons and holes are calculated as a function of temperature. These results are to within a few meV in agreement with previously published optical data. Using the principle of detailed balance in thermal equilibrium, values of ctp=1×10−7 cm3/s, ctn=2×10−3 cm3/s, and gA?3.2 are estimated for the capture rates and the degeneracy factor, respectively, at room temperature.

Multi-objective design of the energy storage-based combined heat and power off-grid system to supply of thermal and electricity consumption energies

Fu's model [ibid., EDL-3, pp. 292-293, Oct. 1982] is based on the assumption that the thermal energy of electrons or holes in the inversion layer may be increased by the application of a gate field. In the absence of a tangential field (VDS = 0), however, carriers are in thermal equilibrium, regardless of the gate field, and hence can be characterized by a constant fermi level through the inversion layer and substrate. Indeed, as Smith (ref. [4] in Fu's paper) himself points out, the rate of increase in the thermal energy is the (dot) product of the field and the average velocity. If the average velocity is zero, there can be no heating. In fact, even in the case of an arbitrary tangential field E (VDS > 0), so large that the drift velocity is no longer simply pE, the gate field still plays no direct role in increasing the thermal energy, since it is normal to the current flowing in the channel. (To be sure it does affect the size of the current by altering the scattering rates, and hence, in this manner indirectly influences the heating of the carriers.)

Building’s energy efficiency has become a key area in energy saving and emission reduction; thus, heat pumps assisted with renewable energy are of great interest in designing the heating system of buildings. Solar energy is a good renewable energy, but its energy density is relatively low and is not stable. The performance of traditional air source heat pumps is significantly reduced at low-temperature conditions, while the thermal energy of waste bath water in buildings is another alternative heat source although intermittent. Given all of these cases, an integrated heating system with a thermal storage tank was designed, which could collect all the available thermal energy into the tank in real time and serve out the thermal energy for water heating and space heating when being required. Such an integrated heating system was created in our laboratory; its performance was tested and analyzed; results indicated that the whole system had a good performance in energy saving.

Thermal energy evolution and mechanical deformation of monocrystalline yttria-stabilized zirconia nanoparticles in aerosol deposition processes

Supernovae as thermal and kinetic energy input to their environment

Flexible hybrid piezoelectric-thermoelectric generator for harnessing electrical energy from mechanical and thermal energy

Bulk n-type ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Te crystals heavily doped with Ga are known to exhibit strong persistent photoconductivity (PPC) at low temperatures (below \ensuremath{\sim}100 K). In order to identify the origin of the PPC effect, we investigated the electronic properties of deep-level defects present in this material by deep-level transient spectroscopy (DLTS) and by thermally stimulated capacitance (TSCAP) measurements. We used a ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Te crystal with x=0.03 and a Ga doping level of 1\ifmmode\times\else\texttimes\fi{}${10}^{19}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. The DLTS measurements revealed the presence of two deep levels, with thermal activation energies for electron emission of 0.25 and 0.43 eV. The electron capture process to the 0.25-eV level was found to be thermally activated, with a thermal energy barrier of 0.11 eV. DLTS measurements performed after sub-band-gap illumination at low temperatures established that, in addition to the PPC effect, the illumination causes also a strong increase in the concentration of the 0.25-eV states, which persist to temperatures as high as T=200 K. This finding indicates that---in addition to the metastability of conduction electrons with respect to the 0.25-eV states, which results in the PPC below 100 K---the 0.25-eV states are also metastable with respect to other (ground) states from which they are created by photoexcitation. Our TSCAP measurements detected also two transitions to two different deep levels, in agreement with these results. The first of these levels is donorlike, with an activation energy of 0.21 eV. The second level is acceptorlike, and the electron transition to this level requires a thermal energy of several hundreds of meV. Because the concentrations of both the 0.25- and the 0.43-eV states found by DLTS appear to be very close to each other, we propose a single defect model with two charge states, attributing the 0.43-eV level to an acceptorlike two-electron ground state of the defect, and the 0.25-eV level to the excited, donorlike one-electron state. According to this model, the defect possesses a positive Hubbard correlation energy (positive-U system). We discuss a configuration coordinate diagram of the defect in the paper.

Relativistic Sweet-Parker type magnetic reconnection is investigated by relativistic resistive magnetohydrodynamic (RRMHD) simulations. As an initial setting, we assume anti-parallel magnetic fields and a spatially uniform resistivity. A perturbation imposed on the magnetic fields triggers magnetic reconnection around a current sheet, and the plasma inflows into the reconnection region. The inflows are then heated due to ohmic dissipation in the diffusion region, and finally become relativistically hot outflows. The outflows are not accelerated to ultra-relativistic speeds (i.e., Lorentz factor ~ 1), even when the magnetic energy dominates the thermal and rest mass energies in the inflow region. Most of the magnetic energy in the inflow region is converted into the thermal energy of the outflow during the reconnection process. The energy conversion from magnetic to thermal energy in the diffusion region results in an increase in the plasma inertia. This prevents the outflows from being accelerated to ultra-relativistic speeds. We find that the reconnection rate R obeys the scaling relation R S^{-0.5}, where S is the Lundquist number. This feature is the same as that of non-relativistic reconnection. Our results are consistent with the theoretical predictions of Lyubarsky (2005) for Sweet-Parker type magnetic reconnection.

The energy of the general circulation of the atmosphere is mainly supplied by thermal energy, but in some parts of the circulation, say, in temperate latitudes, it is reasonable to consider that the energy of the circulation may be supplied by kinematical process of the earth's rotation.The kinetic energy of the earth's rotation is 242×1036 ergs and the dissipation in the earth's circulation is estimated by Brunt to be 5×107 ergs per m2 per sec.Thus the delay in the earth's rotation of 0.01_??_2 sec. per 100 years is sufficient enough to maintain the general circulation, assuming the total kinetic energy of the earth to be consumed for it.Next the thermal and dynamical energies in the equatorial circulation are compared and V. Bjerknes'model of circulation in temperate region is rejected by quantitative analysis.

As a result of investigating analytically and experimentally the interchangeability between thermal, electrical and magnetic energies, it is proved in the presented study that the electric and magnetic energies have an equivalent grade and nature as the thermal energy. So, the natural flow of electric charges and magnetic flux is associated also by increase of entropy of universe, similar to the heat, and has the same nature of waves as the electromagnetic heat radiation. Casting the Maxwell’s wave equation into an energy frame of reference that replaces the time in wave equations by entropy, it is possible to represent the electric charges and magnetic flux as electromagnetic waves of electric and magnetic potentials. Such results lead to modify exclusively the definition of the physical nature of the electric charge and magnetic flux which is unavailable in literature.

Renewable energy in cities: by the Center for Renewable Resources. Van Nostrand Reinhold Co., New York, 1984