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101.
Sacha inchi (Plukenetia volubilis L., Euphorbiaceae) seed oil is rich in α-linolenic acid, a kind of n-3 fatty acids with many health benefits. To discover the mechanism underlying α-linolenic acid accumulation in sacha inchi seeds, preliminary research on sacha inchi seed development was carried out from one week after fertilization until maturity, focusing on phenology, oil content, and lipid profiles. The results suggested that the development of sacha inchi seeds from pollination to mature seed could be divided into three periods. In addition, investigations on the effect of temperature on sacha inchi seeds showed that total oil content decreased in the cool season, while unsaturated fatty acid and linolenic acid concentrations increased. In parallel, expression profiles of 17 unsaturated fatty acid related genes were characterized during seed development and the relationships between gene expression and lipid/unsaturated fatty acid accumulation were discussed. 相似文献
102.
Polymers are frequently used in applications in which they may be exposed to high rate or impact loading, and there is growing industrial importance in understanding their mechanical behavior at different strain rates. An important aspect of this is the temperature rise due to adiabatic conditions in high rate loading. This paper describes research that has been performed to measure the temperature rise that occurs in specimens undergoing rapid deformation. A novel thermocouple design is presented and applied to PMMA and 20 wt% DINP-plasticized PVC, deformed at moderate and high strain rates. The measurements are accompanied by investigations of strain energy. 相似文献
103.
电热炉温控系统自身具有大时滞和大惯性的特点,常规控制方法难以实现炉温预期的控制效果。针对此问题,提出一种基于改进型延时观测器的电热炉温度复合控制方法,将扰动观测器与延时观测器相结合,在消除系统集总扰动的同时,估计出时滞前的状态变量,简化滑模控制器的设计,提高系统的抗干扰能力,消除时滞危害。将所提控制方法与GPC控制、基于Smith预估器的模糊自适应PID控制进行仿真对比,结果表明:所提控制方案的响应速度更快,超调量几乎为零,抗干扰能力更强,鲁棒性更好。 相似文献
104.
采用超音速火焰喷涂(HVOF)制备了WC-WB-CoCr涂层,研究了温度对WC-WB-CoCr涂层高温摩擦磨损性能的影响。通过SEM、XRD和显微硬度仪对涂层的微观组织、相结构和力学性能进行表征。通过摩擦磨损试验机和拉曼光谱仪研究了WC-WB-CoCr涂层的高温摩擦学性能和氧化产物,采用台阶仪扫描磨痕形貌并计算WC-WB-CoCr涂层的磨损率。结果表明:WC-WB-Co-Cr涂层主要由WC和CoW2B2组成,涂层结构致密,与基体结合紧密;随着磨损试验温度升高,涂层的摩擦系数从0.66降低到0.57,涂层的磨损率随着温度的升高而升高,但是其磨损率增长程度随着温度的升高而降低。在高温磨损过程中,磨痕表面的氧化膜主要由WO3和CoWO4组成,且CoWO4比WO3表现出更好的耐高温磨损性能。涂层的主要磨损机制为氧化磨损、疲劳磨损和粘着磨损。 相似文献
105.
《Journal of the European Ceramic Society》2014,34(7):1727-1732
The dielectric and ferroelectric properties of the ceramic system, (1 − x)Ba0.8Ca0.2TiO3–xBi(Zn0.5Ti0.5)O3, were investigated for compositions 0 ≤ x ≤ 0.4. X-ray powder diffraction patterns indicated tetragonal symmetry at x ≤ 0.05, switching to pseudocubic at x ≥ 0.1, with a single-phase solid solution limit at 0.2 < x < 0.3. The x = 0 and 0.05 samples were ferroelectric; a change to relaxor behaviour occurred at x ≥ 0.1, with broad frequency dependent peaks in plots of relative permittivity versus temperature. A significant reduction in the temperature dependence of relative permittivity occurred at x = 0.3, with ɛr = 1030 ± 15% over the temperature range ∼25–425 °C, and loss tangent, tan δ ≤ 0.01 from 110 °C to 420 °C. The dc resistivity values for x = 0.3 were ∼109 Ω m at 300 °C and ∼106 Ω m at 450 °C. 相似文献
106.
《Food and Bioproducts Processing》2014,92(2):208-225
Ion exchange processes are widely used in the food, bioprocessing and related industries for the isolation of proteins and other ionic species. Traditional ion exchange resins require salts, acids or bases for releasing adsorbed molecules creating a strong saline waste stream with negative environmental and economic impact. Stimuli responsive polymers (SRPs) with ion exchange functional groups can be used to selectively capture and release charged molecules from a complex mixture using physical stimuli to trigger conformational transitions in the polymer. The structural change of the polymers in response to a stimulus may lead to reduced ligand–target molecule interaction resulting in the release of the captured molecule without the use of chemical reagents, thereby reducing the environmental burden associated with ion exchange processes. The use of temperature responsive polymers has already been demonstrated for such applications at analytical scale. However, little progress has been made to extend these discoveries to the development of materials and methods amenable to industrial scale processing. So far, other SRPs such as, electric, magnetic and light responsive polymers remain largely unexplored for such application. This article discusses the potential of temperature responsive and other SRPs for developing sustainable ion exchange processes. It also highlights the material science and engineering challenges that need to be overcome to bring such processes to industrial application. 相似文献
107.
108.
F. Erchiqui 《Drying Technology》2014,32(8):946-959
This article analyzes the influence of frequency, temperature, moisture content, and structural orientation on the applicability of the Beer-Lambert law for various wood species using radio frequency and microwave radiation. To achieve this objective, the study compares the power dissipation computed from Maxwell's equation and Lambert's power law. The wood species considered are white oak (Quercus alba), Douglas fir (Pseudotsuga menziesii), trembling aspen (Populus tremuloides), white birch (Betula paperyfera), yellow birch (Betula alleghaniensis), sugar maple (Acer saccharum), and four commercial hardboards. The dielectric constant and dielectric loss factor are examined as a function of moisture conditions, temperature, frequencies, and the three principal structural orientations. The study involved 3,000 complex dielectric constants. It was found that the radial critical thickness is somewhat smaller than the tangential critical thickness (0.95 times smaller) and the longitudinal critical thickness is significantly smaller than the radial (0.52 times). It was demonstrated that the critical thickness L crit above which the Beer-Lambert law is valid for all of the wood species studied under various conditions obeys the following conditions: log10(L crt) = 0.999 log10(β?1) + 0.4122, where β?1 is the penetration depth (cm). In the case of microwave radiation, the critical thickness can be estimated from L crt = 2.615 β?1 ? 0.0626. Finally, a model is proposed to take into consideration the effect of moisture content with frequency (or with attenuation constant). 相似文献
109.
110.