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331.
Different defect chemical models for calculation of ionic and electronic defect concentrations are discussed regarding their applicability to transition metal perovskite-type oxides (ABO3 – ) with large ranges of oxygen non-stoichiometry. A point defect model, which allows simultaneous consideration of three different B-site species concentrations as a function of the oxygen partial pressure is compared to a simple point defect model, considering only two different B-site species. Additionally, a model assuming electrons/holes as negative resp. positive electronic charge carriers is presented. Further, models involving association of point defects in different complexes are discussed. Examples are given for fits of experimental data of La1 – xSrxBO3 – (x = 0.6, B = Fe, Co) to selected models in the temperature range 700–900_C and oxygen partial pressures 10– 5 < pO2/atm < 1. 相似文献
332.
Cites clinical examples, personal experience, and empirical research demonstrating that the values of psychotherapists affect diagnoses, as well as the process and goals of therapy. Some therapists believe that values should not influence therapy. Thus, indirect ways of dissemination of values may be used as shown by clinical illustrations. The author holds a value-determined image of psychotherapy, in which therapeutic schools are viewed as "perceptual houses" to which the client is being converted. The advantages of making the public aware of the role of values in psychotherapy are briefly discussed. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
333.
Developing commingled yarn technologies and understanding the fundamental interface nanostructures of reinforcement and thermoplastic
filaments are of significant current interest. Previous research on commingled yarns was mainly focused on the air-jet texturing
process, while the mechanical properties of the composites are strongly influenced by the impregnation homogeneity, the polymer
sizing properties and consolidation process. Here, we report a unique melt spinning equipment for E-glass fiber which is compatibly
combined with a melt spinning extruder to manufacture commingled yarns. The in-situ commingling enables to combine homogeneously
both glass and polypropylene filament arrays in one processing step and without fiber damage compared to commingling by air
texturing. Variation of processing conditions are investigated, i.e. sizings, diameter ratios, and arrangements of sizing/finish
application related to intermingling of filament arrays. A rapid processing is achieved because of good intermingling and
the low flow paths. We found that the sizing enables a good strand integrity with the polypropylene yarn. The interfacial
adhesion can be improved with a sizing for glass fibers consisting of aminosilane and maleic anhydride grafted polypropylene
film former, which results in both improved transverse tensile strength and compression shear strength. We also found that
a very small amount of single-wall carbon nanotubes (SWNTs) in the sizing provides significantly improved interfacial adhesion
strength. This is attributed to the change in fracture behavior of the nano-structured interface and morphology of the model
single-fiber composites. 相似文献
334.
Investigation on adhesion, interphases, and failure behaviour of cyclic butylene terephthalate (CBT)/glass fiber composites 总被引:1,自引:0,他引:1
Edith Mder Shang-Lin Gao Rosemarie Plonka Jing Wang 《Composites Science and Technology》2007,67(15-16):3140-3150
Interphases exist in hybrid materials and significantly influence their mechanical performance. To find a bridge between the microscopic and macroscopic mechanical properties, this work investigates the microscopic nature of glass fiber surfaces and glass/CBT interphases in terms of topography, fractography, and adhesion properties. The variations in glass fiber surface properties result from the different sizings. Using the single fiber pull-out test, AFM, and ζ potential tests, it is shown that the interfacial bond strengths in CBT resin composites can vary depending on the kind of sizing formulation and properties. The greatest adhesion strength is achieved by aminosilane sizings with epoxy resin film former. The surface roughness of the fibers can be varied by sizings with different content and ζ potential values, which has no significant contribution to interphase adhesion strength from ‘mechanical interlocking’. For the systems with film formers, cohesive failure occurs and similar values of both interfacial adhesion strength, τd, and fracture energy release rate, Gic, are obtained, in which τd approaches the shear yield strength of CBT matrix. A further enhancement of interfacial adhesion is limited by the mechanical properties and the non-homogeneous microstructure of CBT resin due to the less-than-perfect CBT polymerization. 相似文献
335.
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337.
There exist many different formalisms to model the notion of resource bounded truth-table reduction. Most papers in which truthtable reductions appear refer to the seminal paper of Ladner, Lynch and Selman for a definition. The definition of truth-table reductions given there however, pertains to only one of the possible incarnations of the notion. For larger resource bounds, this definition often coincides with other-often implicitly used-definitions of the notion. In this paper we focus our attention on resource bounds for which the various definitions probably donot pertain to the same notion. In particular, we show that coincidence of different notions implies coincidence of complexity classes likeNC
1,LOG, andP, which are widely believed to be different. 相似文献
338.
339.
Sterols and Stanols in Foods and Dietary Supplements Containing Added Phytosterols: A Collaborative Study 下载免费PDF全文
Cynthia T. Srigley Steven L. Hansen Sean A. Smith Anjalika Abraham Eileen Bailey Xiang Chen Soo Hui Chooi Lisa M. Clement Michael Dao Ali Reza Fardin Kia Barb Mitchell Mohit Mogla Juan Antonio Ruano Ortiz Keith Persons Edith von Kries George Ware Jason Wubben Richard Cantrill 《Journal of the American Oil Chemists' Society》2018,95(3):247-257
An international, multilaboratory collaborative study was carried out to evaluate the performance of Official Method Ce 12‐16 of the American Oil Chemists’ Society (AOCS) for the determination of plant sterols and stanols, collectively referred to as phytosterols, in foods and dietary supplements containing added phytosterols and in the phytosterol food additive concentrates used to prepare such products. AOCS Official Method Ce 12‐16 involves the extraction of free sterols/stanols and saponified steryl/stanol esters followed by the gas chromatographic separation and flame ionization detection of phytosterol trimethylsilyl ether derivatives. A total of 14 laboratories from six countries successfully completed the analysis of collaborative samples of foods (e.g., baked goods, beverages, margarines; n = 9), dietary supplements (n = 5), and phytosterol concentrates (n = 4). Study results for the contents of total phytosterols (weight/weight) were 0.19–8.4% for foods, 8.7–49% for dietary supplements, and 57–97% for concentrates. AOCS Official Method Ce 12‐16 showed acceptable performance for total and individual phytosterols, indicating that this method was suitable for the determination of added phytosterols in a wide variety of market products and concentrates. AOCS Official Method Ce 12‐16 is appropriate for the determination of the five major phytosterols (i.e., campesterol, stigmasterol, β‐sitosterol, campestanol, and sitostanol) that are the subject of the United States Food and Drug Administration's health claim for phytosterols and the reduced risk of coronary heart disease. 相似文献
340.
The distinction between several components of mental workload is often made in the ergonomics literature. However, measurements used are often established from a global score, notably with several questionnaires that originally reflect several dimensions. The present study tested the effect of driving situation complexity, experience and subjective levels of tension and alertness on each dimension of the NASA-TLX questionnaire of workload, in order to highlight the potential influence of intrinsic, extraneous and germane load factors. The results showed that, in complex situation, mental, temporal and physical demand (load dimensions) increased, and that novice drivers presented high physical demand when subjective tension was low on performance. Moreover, increase of mental and physical demand increased effort. It thus, appears essential to distinguish the different components of mental workload used in the NASA-TLX questionnaire.
Practitioner Summary: Currently, global score of NASA-TLX questionnaire is used to measure mental workload. Here, we considered independently each dimension of NASA-TLX, and results showed that mental load factors (driving situation complexity, experience, subjective tension and alertness) had a different effect on dimensions, questioning global score use to evaluate workload. 相似文献