The heat capacities of D-galactose and galactitol were measured on a quantum design physical property measurement system(PPMS) over a temperature range of 1.9―300 K, and the experimental data were fitted to a function of T using a series of theoretical and empirical models in appropriate temperature ranges. The fit results were used to calculate thermodynamic function values,Cp,mθ,Δ0TSmθ, and Δ0THmθfrom 0 K to 300 K. The standard molar heat capacity, entropy and enthalpy values of D-galactose and galactitol at 298.15 K and 0.1 MPa were determined to be Cp,mθ =(227.96±2.28) and (239.50±2.40) J·K-1·mol-1,Smθ= (211.22±2.11) and (230.82±2.30) J·K-1·mol-1 and = Hmθ (33.95±0.34) and (36.57± 0.37) kJ/mol, respectively. 相似文献
Highly (100)-oriented (Pb1?x?yLaxCay)Ti1?x/4O3 (, ; , ; , ) thin films were deposited on Pt/Ti/SiO2/Si substrates at a low temperature of 450?°C via a sol–gel route. It was found that all the (Pb1?x?yLaxCay)Ti1?x/4O3 thin films could be completely crystallized and the content of La/Ca showed a significant effect on the electrical properties of films. Among the three films, the (Pb1?x?yLaxCay)Ti1?x/4O3 (, ) thin film exhibited the enhanced overall electrical properties, such as a low dielectric loss () and leakage current ( A/cm2), a high recoverable energy density (Wre ~ 15 J/cm3), as well as a large pyroelectric coefficient (p ~ 190 μC/m2K) and figure of merit (K). The findings suggest that the fabricated thin films with a good (100) orientation can be an attractive candidate for applications in Si-based energy storage and pyroelectric devices. 相似文献
An Fe layer was sputter-deposited onto porous alumina templates and Kapton respectively. Fe layer on the porous alumina templates formed an antidot arrays nanostructure, while Fe layer on the Kapton substrate formed a continuous film. Scanning electron microscopy and grazing incidence X-ray diffraction were employed to characterize the morphology and crystal structure of the Fe antidot arrays and continuous film, respectively. The temperature dependence of magnetic properties was shown in the temperature range 2-300 K. The irreversibility of the magnetization of Fe antidot arrays film, as measured in zero-field cooling (ZFC) and field cooling (FC) states, was attributed to the pinning effect of the holes. 相似文献
When GaAs–Si and GaAs–AlGaAs heterostructures are exposed to γ-quanta, radiation stimulated ordering is observed. However, the gettering efficiency in such systems falls for layer widths more than 1 μm. For this reason we seek effective methods of radiation resistance improvement of materials in which one would expect point radiation defects to be gettered not only at defect boundaries, but also in the active layer volume.
S.i.GaAs–s.i.AlxGa1−xAs–nGaAs : Te heterostructures are presented with epitaxial layers (doped with Yb or undoped), obtained by means of LPE (liquid-phase epitaxy). The electron concentration in nGaAs was found to be (1–3)×1018 cm−3 for widths 1–3 μm. The samples were exposed to 60Co γ-quanta with doses of 105–107 rad.
Investigations of irradiated samples by means of low-temperature (4.2 K) photoluminescence have shown considerable decrease of exciton halfwidth in the boundary spectra of nGaAs : Te : Yb epitaxial layers in comparison with nGaAs : Te layer spectra. This is caused by background impurity gettering which happens on the s.i.AlxGa1−xAs–nGaAs heteroboundaries as well as in deformed regions in the epitaxial layer volume. Formation of such regions is caused by the difference between the covalent radii of Yb atoms and GaAs lattice atoms. The maximum effect of radiation stimulated gettering of dopants in nGaAs epitaxial layers is observed for Yb concentrations which are equal to 10−4–10−5 atomic fractions in a solution-melt.
It is determined that the deformed regions in epitaxial layer volumes and heteroboundaries could be efficient drains for point radiation defects which form under radiation exposure. The investigations carried out showed that the doping of an epitaxial layers by rare-earth impurities provides considerable improvement in forming radiation resistant III–V materials. 相似文献
The major objective of this work is to numerically investigate the interacting physical and chemical phenomena that characterize
the flow in a stabilized cool flame diesel fuel spray evaporation system. A two-phase RANS computational fluid dynamics code
has been developed and used to predict the characteristics of the developing turbulent, multiphase, multi-component, reactive
flow-field. The code employs a Eulerian–Lagrangian approach, taking into account the mass, momentum, thermal and turbulent
energy exchange between the phases. A variety of physical phenomena, such as turbulent dispersion, droplet evaporation, droplet-wall
collision, conjugate heat transfer, drift correction, two-way coupling are taken into account by implementing respective sub-models.
Two alternative modelling approaches for the simulation of cool flame reactions have been validated and evaluated by comparing
numerical predictions with experimental data from two atmospheric pressure, evaporating Diesel spray, Stabilized Cool Flame
reactors. Both models have achieved good quantitative agreement in the majority of the considered test cases. The results
have been used to estimate the local physical and chemical characteristic time scales of the occurring phenomena, thus allowing,
for the first time, the classification of stabilized cool flames. 相似文献
A new method of combining low-temperature Shpol'skii effect with non-linear variable-angle synchronous fluorescence spectrometry (L-NLVASFS) has been proposed to increase spectral resolution. This coupled method was applied successfully to the simultaneous identification and quantification of some polycyclic aromatic hydrocarbons (PAHs) in mixtures, which cannot be determined by non-linear variable-angle synchronous fluorescence spectrometry at room-temperature (R-NLVASFS). The usefulness of this method is demonstrated by the analyses of synthetic mixtures and several real samples of airborne particulates. 相似文献