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241.
    
Photo‐oxidative degradation of polyethylene triggers significant deterioration in the polymer properties. Much interest is aimed at characterizing and possibly predicting photo‐oxidative damages, at early stages, prior to the occurrence of profound changes in mechanical properties. Herein, we study the degradation of low‐density polyethylene (LDPE) films, focusing on surface deterioration processes. Thin films of various molecular weights are exposed to accelerated weathering while their chemical, mechanical and morphological characteristics are monitored throughout by apparent contact angle (CA) measurements, Fourier‐transform infrared spectroscopy (FTIR), tensile test, and electron microscopy. A significant decrease in the films' CA during degradation is observed. CA is highly sensitive to two simultaneous phenomena with opposing effect: nanoscale surface roughening and composition changes. We found the latter (specifically the evolution of polar groups) to be the dominant parameter affecting the CA behavior. Consequently, simple CA measurements coincide well with conventional FTIR analysis, and are more sensitive to changes occurring at early stages of degradation. The deterioration in the mechanical properties is also characterized and is found to present poor sensitivity and high variability at these early aging stages. Thus, simple CA measurements could potentially be used as a qualitative indicator for evaluating the aging impact on LDPE. POLYM. ENG. SCI., 59:E129–E137, 2019. © 2018 Society of Plastics Engineers  相似文献   
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243.
介绍了JBZS-1型三相交流逆变电源综合测试仪测量交,直流电压、电流、功率、失真度、频率等参数的测量原理,并阐述了单片机与可编程系统器件、液晶显示器、微型打印机的接口设计和汇编软件设计.  相似文献   
244.
    
The two basic questions in food intake study are what we eat, and how much do we eat. Most research is directed toward the control of how much is eaten. This is likely the result of the increased number of individuals with eating disorders in the Western world. Feeding behavior is highly complex, and is controlled by many psychological, physiological, biochemical, and immunological factors. The aim of this review is to clarify the involvement of fatty acids in eating disorders such as anorexia and binge eating disorder. The review will describe the modified fatty acid profile observed in individuals with anorexia or binge eating disorder, and discuss on what factors fatty acids can exert beneficial effects. In addition, the differences and similarities between anorexia and binge eating disorder will be discussed. We suggest that beneficial effects of essential fatty acids on both anorexia and binge eating disorder can be explained by the stabilizing effect of those fatty acids on the neuronal membrane fluidity index.  相似文献   
245.
    
Oreochromis fishes exhibit variability of sex-determination (SD) genes whose characterization contributes to understanding of the sex differentiation network, and to effective tilapia farming, which requires all-male culture. However, O. niloticus (On) amh is the only master-key regulator (MKR) of SD that has been mapped (XY/XX SD-system on LG23). In O. aureus (Oa), LG3 controls a WZ/ZZ SD-system that has recently been delimited to 9.2 Mbp, with an embedded interval rich with female-specific variation, harboring two paics genes and banf2. Developing genetic markers within this interval and using a hybrid Oa stock that demonstrates no recombination repression in LG3, we mapped the critical SD region to 235 Kbp on the orthologous On physical map (p < 1.5 × 10−26). DNA-seq assembly and peak-proportion analysis of variation based on Sanger chromatograms allowed the characterization of copy-number variation (CNV) of banf2. Oa males had three exons capable of encoding 90-amino-acid polypeptides, yet in Oa females, we found an extra copy with an 89-amino-acid polypeptide and three non-conservative amino acid substitutions, designated as banf2w. CNV analysis suggested the existence of two to five copies of banf2 in diploidic Cichlidae. Disrupting the Hardy–Weinberg equilibrium (p < 4.2 × 10−3), banf2w was concordant with female determination in Oa and in three cichlids with LG3 WZ/ZZ SD-systems (O. tanganicae, O. hornorum and Pelmatolapia mariae). Furthermore, exclusive RNA-seq expression in Oa females strengthened the candidacy of banf2w as the long-sought LG3 SD MKR. As banf genes mediate nuclear assembly, chromatin organization, gene expression and gonad development, banf2w may play a fundamental role inducing female nucleus formation that is essential for WZ/ZZ SD.  相似文献   
246.
梁仕然 《中国园林》2020,36(7):129-133
依据古代文献对惠州西湖核心区域建筑布局复原的基础上,借用《园冶》\"相地\"\"立基\"之说,并结合实测数据探讨了主要建筑的选址、造景意图和自然山水条件之间的联系。提出古代惠州西湖建筑的选址布局并非简单的空间布置,而是融合古典造园理念、宏观山形地势走向及风水思想,最终形成具有较深刻、丰富的内涵,并符合传统山水审美的规划设计。通过古惠州西湖为个案探索中国古代大尺度景观的\"民族特色\"。  相似文献   
247.
The primary objective of this four-way crossover study was to compare the concentration-time profile of paracetamol from a new rapidly absorbed paracetamol tablet containing sodium bicarbonate (PS) with a conventional paracetamol tablet (P), in a panel of 28 fed and fasted healthy volunteers. The results demonstrated that paracetamol was absorbed more rapidly from tablets containing sodium bicarbonate compared to conventional tablets, as indicated by a shorter tmax in both the fed and fasted state and a higher Cmax in the fasted state. The two formulations were bioequivalent with respect to area under curve (AUC). Food did not affect the extent of absorption from either formulation, as indicated by AUC, however, food did reduce the rate of absorption from both formulations, as indicated by a longer tmax and a lower Cmax. Metabolic activation of paracetamol to its oxidation metabolites, as assessed by combined partial clearances to subsequent secondary metabolites cysteine and mercapturic acid conjugates, indicated that the two formulations were bioequivalent in this respect.  相似文献   
248.
To test the proposition that an intake, multivariate battery of 42 psychometric predictors can predict duration of stay in rehabilitation and competence in ambulation and self-care, multiple-regression equations were computed for 54 Ss with left hemiplegia, and their retrospective outcome scores were highly accurately predicted. To reduce administration cost, redundant information was deleted. A compact battery of 27 variables was thus obtained, and the program was repeated. Resulting multiple correlations and predictive accuracy were only slightly less than those arrived at with the full battery. A cross-validation study on 15 new Ss yielded essentially identical results. It is concluded that the prediction of outcomes from psychometric measures, taken at the initiation of the rehabilitation program is highly feasible. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
249.
An ``Alternating Sequential/Parallel' system, the Mopps was introduced a few years ago and is modified despite the fact that it solved satisfactorily a number of real-time problems. The new system, the ``Topps' is described and compared to Mopps in Section II and two applications are chosen to prove it to be superior. In Section III, the advantage of having a third basic, the ``ring' mode, is illustrated when solving sets of linear equations with band matrices. In Section IV, the advantage of having independent I/O for the slaves is illustrated for biomedical signal analysis.  相似文献   
250.
Transesophageal echocardiographic findings and their effect on disease management were evaluated in 216 patients with suspected cardiovascular source of emboli. Clinical and transesophageal echocardiographic findings were useful in defining pretest probability for finding a probable cardiovascular source of emboli on transesophageal echocardiography.  相似文献   
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