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排序方式: 共有390条查询结果,搜索用时 156 毫秒
291.
Adaptive fin motion has long been the evolutionary means by which birds, fish, and various water-dwelling mammals create a propulsive thrust to propel them either through air or water. During the past decade, this particular phenomenon of kinematic motion has been studied by various scholars to gain an understanding of how and why the large relative efficiencies and body accelerations are attained. Invariably, the studies are interested in gaining an understanding of the phenomena so that these motions and kinematics can be applied to engineering design efforts. Various groups have built propulsive devices that are intended to mimic motions of these highly efficient adaptive motion propulsors with various degrees of successes. This paper summarizes some of these findings, bridging constructal theory and adaptive motions, with emphasis on their application. It also presents results of a research effort made by the writers to incorporate these concepts into low Reynolds number flexible turbine design. 相似文献
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This paper presents the analytical study of heat and mass transfer in a two-dimensional time-dependent flow of Williamson nanofluid near a permeable stretching sheet by considering the effects of external magnetic field, viscous dissipation, Joule heating, thermal radiation, heat source, and chemical reaction. Suitable transformations are introduced to reformulate the governing equations and the boundary conditions convenient for computation. The resulting sets of nonlinear differential equations are then solved by the homotopy analysis method. The study on the effects of relevant parameters on fluid velocity, temperature, and concentration profiles is analyzed and presented in graphical and tabular forms. Upon comparison of the present study with respect to some other previous studies, a very good agreement is obtained. The study points out that the transfer of heat can substantially be enhanced by decreasing viscoelasticity of the fluid and the transfer of mass can be facilitated by increasing permeability of the stretching sheet. 相似文献
294.
该研究探讨了脉冲强光(IPL)预处理联合控湿干燥对香菇储藏品质的影响。研究发现,脉冲强光预处理可以降低贮藏期间新鲜和干香菇的呼吸速率,分别为对照的76.69%和84.65%;脉冲强光预处理提高了还原糖的保留率。新鲜和干香菇在贮藏期间对照的多酚氧化酶(PPO)活性分别是IPL预处理样品的1.73倍和1.39倍,酶促褐变反应受到抑制,也因此提高了总酚的保留率。IPL可以提高鲜、干香菇在贮藏期间的品质、多糖保留率和抗氧化能力,延缓软化。IPL处理降低了新鲜香菇在贮藏期间的菌落总数(从6.43~8.02 log CFU/g减少至3.29~4.66 log CFU/g),但是对干香菇在贮藏期间菌落总数影响较小。与热烫处理相比,脉冲强光处理提升香菇贮藏品质更佳。因此脉冲强光可以作为一种稳定的预处理手段用于香菇干燥和保鲜中。 相似文献
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Chaoting Wen Jixian Zhang Yuqing Duan Haihui Zhang Haile Ma 《Journal of food science》2019,84(12):3330-3340
There is a growing demand in reusing agro‐industrial waste to enrich food proteins and develop new protein‐related products. Brewer's spent grain (BSG), the byproducts generated from the processing of beer‐brewing industry, is rich in abundant protein (26 to 30%) with good physicochemical properties and nutritional benefits. BSG is mainly composed of four proteins including hordein, gluten, globulin, and albumin. The methods for extracting protein from BSG mainly include alkali extraction, ultrasonic‐assisted extraction, and organic solvent extraction, among others. However, little researches have described the functional properties of Brewer's spent grain protein (BSGP) and how it can be improved by enzymatic modification. Additionally, BSG protein hydrolysates (BSGPHs) have good bioactivities, mainly including antioxidant, antiinflammatory, and angiotensin‐I–converting enzyme inhibitory activities, among others. Based on the above situation, this review provides a comprehensive overview about the isolation, physicochemical features, application of the BSGP. In addition, the functional properties and biological activities of BSGPHs are also emphasized. The purpose of this review is to provide an up‐to‐date summary of BSGP research, and to broaden the market potential of this emerging protein in food industry. Besides, this review provides a reference to study the use of BSGP or hydrolysates for a variety of purposes in‐depth, including pharmaceutical, food, and industrial applications. 相似文献
297.
Potential use of DNA barcodes in regulatory science: applications of the Regulatory Fish Encyclopedia 总被引:6,自引:0,他引:6
Yancy HF Zemlak TS Mason JA Washington JD Tenge BJ Nguyen NL Barnett JD Savary WE Hill WE Moore MM Fry FS Randolph SC Rogers PL Hebert PD 《Journal of food protection》2008,71(1):210-217
The use of a DNA-based identification system (DNA barcoding) founded on the mitochondrial gene cytochrome c oxidase subunit I (COI) was investigated for updating the U.S. Food and Drug Administration Regulatory Fish Encyclopedia (RFE; http://www.cfsan.fda.gov/-frf/rfe0.html). The RFE is a compilation of data used to identify fish species. It was compiled to help regulators identify species substitution that could result in potential adverse health consequences or could be a source of economic fraud. For each of many aquatic species commonly sold in the United States, the RFE includes high-resolution photographs of whole fish and their marketed product forms and species-specific biochemical patterns for authenticated fish species. These patterns currently include data from isoelectric focusing studies. In this article, we describe the generation of DNA barcodes for 172 individual authenticated fish representing 72 species from 27 families contained in the RFE. These barcode sequences can be used as an additional identification resource. In a blind study, 60 unknown fish muscle samples were barcoded, and the results were compared with the RFE barcode reference library. All 60 samples were correctly identified to species based on the barcoding data. Our study indicates that DNA barcoding can be a powerful tool for species identification and has broad potential applications. 相似文献
298.
Thermal and single frequency counter‐current ultrasound pretreatments of sodium caseinate: enzymolysis kinetics and thermodynamics,amino acids composition,molecular weight distribution and antioxidant peptides
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简述了表面分子印迹聚合物载体研究的最新进展。根据载体种类以及表面修饰方法的不同,分别介绍了以无机材料为载体和以壳聚糖为基质的表面分子印迹技术,并对表面分子印迹聚合物载体的发展前景进行了展望。对无机材料的表面修饰主要通过引入烷基化试剂的功能基团(如氨基、苄基等),再通过分子印迹的方法制备出理想的表面分子印迹聚合物;而对壳聚糖的修饰主要通过各种交联方法,从而获得单一基质载体或者壳聚糖杂化材料载体。文中指出,与传统方法相比,新型材料的吸附性能优良、回收利用率高、颗粒均一。但是,该材料制备过程中的微观行为模式以及功能单体同目标分子的成键规律等还有待进一步研究。 相似文献