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An improved microwave Clevenger apparatus for distillation of essential oils from orange peel 总被引:5,自引:0,他引:5
Microwave Clevenger or microwave accelerated distillation (MAD) is a combination of microwave heating and distillation, performed at atmospheric pressure without added any solvent or water. Isolation and concentration of volatile compounds are performed by a single stage. MAD extraction of orange essential oil was studied using fresh orange peel from Valencia late cultivar oranges as the raw material. MAD has been compared with a conventional technique, which used a Clevenger apparatus with hydro-distillation (HD). MAD and HD were compared in term of extraction time, yields, chemical composition and quality of the essential oil, efficiency and costs of the process. Extraction of essential oils from orange peels with MAD was better in terms of energy saving, extraction time (30 min versus 3 h), oxygenated fraction (11.7% versus 7.9%), product yield (0.42% versus 0.39%) and product quality. Orange peels treated by MAD and HD were observed by scanning electronic microscopy (SEM). Micrographs provide evidence of more rapid opening of essential oil glands treated by MAD, in contrast to conventional hydro-distillation. 相似文献
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Low-pressure structural properties of simple cubic polonium are explored through first-principles density-functional theory based relativistic total energy calculations using pseudopotentials and plane-wave basis set, as well as linear-response theory. We have found that Po undergoes structural phase transition at low pressure near 2 GPa, where the element transforms from simple cubic to a mixture of two trigonal phases namely, hR1 (α=86°) and hR2 (α=97.9°) structures. The lattice dynamics calculations provide strong support for the observed phase transition, and show the dynamical stability (instability) of the hR2 (hR1) phase. 相似文献
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Fabrice Gouanvé H. Phuong-Nguyen Zohra Ferhat Hamida Geneviève Delmas 《Colloid and polymer science》2005,283(9):994-1006
A new technique to investigate the nano-structure of ethylene–propylene (EP) random copolymers has been developed. It consists in the measurement of the turbidity which develops at a lower critical solution temperature (LCST) in pentane solutions. The information on the solution comes from different types of turbidity obtained during a step-by-step temperature increase. The transient turbidity (hi) is associated with random coils (I) and structured coils (II) while the stable turbidity comes from aggregates (III). The proportion of (I), (II) and (III) depends on the solution history and on the solvent. The Mw distribution can be obtained from the set hi (Ti) of (I). Turbidity (II) has an unexpected gap in the hi (Ti) trace. The gap (10–20 K) is explained by the presence of two entities in solution. Their temperatures of phase separation permit their identification as monomolecular micelles, whose outer core is either E-rich or P-rich. This nano-structure is thought to exist in the solid and also in solution as a metastable state. The technique can differentiate between mobile chains in solutions (I, II) and attached chains in a network (III) through the sedimentation behaviour of the concentrated phase. Three samples with a similar (EP) content (0.75) made with different catalysts have been analysed by LCST and slow calorimetry. 相似文献
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Maharram?Z.?ZarbaliyevEmail author Ibrahim?H.?Mutlu Ferhat?Aslan 《Journal of Sol-Gel Science and Technology》2011,59(1):153-157
This study describes the In2S3 semiconductor thin film coating on glass substrate by sol–gel method. The In2S3 thin film samples were prepared and examined by the X-ray diffraction (XRD), the UV–visible optical absorption and transmission
study, and the Scanning Electron Microscope (SEM) image analyses. The XRD analysis results show that the In2S3 semiconductor thin films prepared by sol–gel method is formed at T~360–520 °C temperature interval. Band gap energy and optical
absorption spectrum analysis of the In2S3 thin films reveal that Eg~2.51 eV for the In2S3 thin films. According to the EDX result the film was In-rich with the In/S = 1.42 ratio. The thickness of prepared In2S3 layer is about 400 nm. 相似文献
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We present first-principles pseudopotential plane-wave calculations to explore the effects of alloying of non conventional III–V compound GaN with bismuth. We found a highly nonlinear reduction of the energy gap of GaN for small Bi composition. Consequently the optical band gap bowing is found extremely important and composition dependent. The stronger contribution is due principally to structural and, to less extent, to charge transfer effects. Moreover, because of strong relativistic effects caused by bismuth, we found a giant bowing for the spin–orbit splitting energy of valence band, by far the largest of any III–V ternary alloys. 相似文献
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Ferhat Bekhoucha Said Rechak Laëtitia Duigou Jean-Marc Cadou 《Nonlinear dynamics》2013,74(4):1281-1296
This work deals with forced vibration of nonlinear rotating anisotropic beams with uniform cross sections. Coupling the Galerkin method with the balance harmonic method, the nonlinear intrinsic and geometrically exact equations of motion for anisotropic beams subjected to large displacements, are converted into a static formulation. This latter is treated with two continuation methods. The first one is the asymptotic-numerical method, where power series expansions and Padé approximants are used to represent the generalized vector of displacement and the frequency. The second one is the pseudo-arclength continuation method. Numerical tests dealing with isotropic and anisotropic beams are considered. The natural frequencies obtained for prismatic beams are compared with the literature. Response curves are obtained and the nonlinearity is investigated for various geometrical conditions, excitation amplitudes and kinematical conditions. The nonlinearity related to the angular speed for prismatic isotropic beam is thus identified. The stability of the solution branch is examined, in the frequency domain using the Floquet theory. 相似文献
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The optical properties of hexagonal InN have been studied using the all-electron approach based on density functional theory (DFT). The full-potential augmented plane wave method is employed with two different exchange-correlation potentials, the Perdew–Wang (PW) and the Engel–Vosko (EV) approximations. In addition, both non-relativistic and relativistic approximations are considered. We found that the PW and relativistic approximations give a metallic ground state; whereas using the EV and non-relativistic approximations a semiconductor phase is obtained, opening the gap up to 0.83 eV. Besides, the calculated interband transitions of the complex dielectric function up to 13 eV show favourable agreement with the recent spectroscopic ellipsometry results. 相似文献
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We have performed ab initio self-consistent calculations based on the full potential linear augmented plane-wave method (FP-LAPW) with the local density approximation (LDA) and the Generalised Gradient Approximation (GGA) to investigate the relativistic effects, on the structural, and transport properties of III–V compounds. We found that the stabilisation (destabilisation) of s, p∗(p,d) orbital energies (i) reduces the lattice parameters of III–V compounds, considerably reduces the band gaps of the III–V compounds, (ii) reduces the effective masse, and (iii) induces strong spin orbit splitting of heavier III–V compounds. Furthermore we circumvent the negative gap problem by combining non relativistic and Engel–Vosko approximations. These approaches open the gap of the most III–V compounds, and leads to a realistic band structure. 相似文献
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The Gross-Pitaevskii equation, which is the governor equation of Bose-Einstein condensates, is solved by first order perturbation expansion under various q-deformed potentials. Stationary probability distributions reveal one and two soliton behavior depending on the type of the q-deformed potential. Additionally a spatial shift of the probability distribution is found for the dark soliton solution, when the q parameter is changed. 相似文献