电压稳定剂作用机理及应用范围

从塑料工业用防老剂和其它助剂中筛选三种电压稳定剂，研究了它们的作用机理和适用范围，按作用机理将所选电压稳定剂分为自由基清除剂和弱电解质两类，前者可抑制均匀场下的电老化和非均匀场下的电树枝化，但难以用于交联聚乙烯，而后者只能抑制电网枝化。     

Aging and the detection of observer and moving object collisions.

The authors examined age-related differences in the detection of collision events. Older and younger observers were presented with displays simulating approaching objects that would either collide or pass by the observer. In 4 experiments, the authors found that older observers, as compared with younger observers, had less sensitivity in detecting collisions with an increase in speed, at shorter display durations, and with longer time-to-contact conditions. Older observers also had greater difficulty when the scenario simulated observer motion, suggesting that older observers have difficulty discriminating object motion expansion from background expansion from observer motion. The results of these studies support the expansion sensitivity hypothesis-that age-related decrements in detecting collision events involving moving objects are the result of a decreased sensitivity to recover expansion information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prefrontal and parietal regions are involved in naming of objects seen from unusual viewpoints.

Object naming is commonly used for demonstrating semantic memory abilities, known to be affected in normal aging. Yet, neuropsychological assessments of older people do not reflect irregularities. The authors used a test with 2 levels of naming complexity by 2 kinds of stimuli: common objects pictured from a conventional viewpoint (usual condition) or from an unconventional viewpoint (unusual condition). The authors studied naming performance with 129 healthy participants, aged 20-85 years. For the usual stimuli, the success rate was high (90.9%), with no reduction in performance until 65 years of age. However, for the unusual stimuli, there was a marked reduction in performance with age. Brain activity was studied on 11 healthy young participants (20-30 years of age) using functional magnetic resonance imaging. The usual condition activated brain regions associated with visual perception, language, and memory. Additional brain regions associated with semantic searching and decision making were obtained in the unusual condition in the prefrontal cortex (Brodmann's area [BA] 9 and BA 47) and anterior cingulate (BA 32). The results suggest that the poor naming performance for unusual-viewed objects in older people might be related to the shrinkage of frontal gray matter with age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Estimating creep deformation of glass-fiber-reinforced polycarbonate

Thermoplastic resin and fiber-reinforced thermo-plastics (FRTPs) were used without post-cure treatment as “molded material.” For such materials, creep behavior and physical aging occur simultaneously. This study examined the creep behavior of polycarbonate (PC) and glass-fiber-reinforced polycarbonate (GFRPC) injection moldings, including the effect of physical aging and fiber content, and determined that the time–temperature superposition principle could be applied to the creep behavior for different fiber contents. The effects of physical aging on creep behavior were evaluated quantitatively on pure resin and with various fiber contents without heat treatment. We found that the effect of physical aging could be evaluated with the proposed factor, “aging shift rate.” To discuss the linearity of viscoelasticity in FRTPs, this study used two shift factors: time and modulus shift factors. The fiber content affected creep behavior by both retarding and restraining it through changing the elastic modulus. This was shown by generating a grand master curve of creep compliance, which included the effects of time, temperature, and fiber content. Using the grand master curve of creep compliance and shift factors, it was possible to estimate the creep deformation of molded materials under varying conditions and fiber contents. The estimated creep deformation gave a very good fit to the experimental creep deformation.     

Production of senescent cells of Saccharomyces cerevisiae by centrifugal elutriation

The centrifugal elutriator has been used as a baby machine by loading the chamber with a population of mixed-generation daughter cells and allowing this population to grow, divide and age under continuous washing-out of newborn daughter cells. Clear peaks in the number of elutriated cells were reproducibly obtained for at least ten generations. The parent cells growing in the chamber continued to divide at the steady-state generation time of 95–100 min, showing no change in cycle time during aging. The washed-out daughter cells increased in volume during the first five generations from their steady-state value of 17 μm³ to a maximum of 34 μm³. As to be expected, the generation times of these large daughters, determined in a synchronous batch culture, were shorter (130 min) than that of the steady-state daughters (240 min), even when derived from 15-generation parents. No indication for a volume increase of daughter cells without bud was observed when a population was allowed to grow in the chamber without washing-out the smaller daughter cells. The 15-generation parent population, recovered from the chamber, had an average volume of 80 μm³ and consisted of: (i) 71% cells with more than ten scars, (ii) 13% cells with one to nine scars, and (iii) 17% daughter cells. The production of senescent cells by undisturbed growth in the elutriator chamber has been prolonged to 29 generations. The method is therefore suitable to examine what factors determine the life span of budding yeast.     

Editorial

This special issue is devoted to a study of psychological perspectives of aging and gerontology. The present issue covers topics and themes that relate broadly to the perceptions and psychological functioning of older adults: Their motivations, their happiness and activities, their personal meanings of life and quality of life concerns, their sexual expressions, their television viewing, and how all these relate to successful aging. Also included are perspective-taking papers on problems of stress and depression and how these relate to the psychological health and welfare of older adults. The reader will find a rich assortment of research-based gerontology papers attesting to the vigorous activity of Canadian psychologists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of long-term thermal aging on the microstructural evolution of nuclear reactor pressure vessel materials: an atom probe study

Atom probe field ion microscopy (APFIM) investigations of the microstructure of unaged (as-fabricated) and long-term thermally-aged (˜100 000 h at 280°C) surveillance materials from commercial reactor pressure vessel steels were performed. This combination of materials and conditions permitted the investigation of potential thermal aging effects. This microstructural study focused on the quantification of the compositions of the matrix and carbides. The APFIM results indicate that there was no significant microstructural evolution after a long-term thermal exposure in weld, plate and forging materials. The matrix depletion of copper that was observed in weld materials was consistent with the copper concentration in the matrix after the stress relief heat treatment. The composition of cementite carbides aged for 100 000 h were compared to the Thermocalc™ prediction. The APFIM comparisons of materials under these conditions are consistent with the measured change in mechanical properties such as the Charpy transition temperature.     

Hygrothermal Aging Effects in Cured Epoxies

The effect of relatively severe hygrothermal aging on the sorption and also the diffusion of water at 40°C has been studied for a number of epoxy networks comprising tetraglycidyl 4,4′-diaminodiphenyl methane, and the curing agent 4,4′-diaminodiphenyl sulphone, 4,4′-diaminodiphenyl methane and 2,2′-dichloro-4,4′-diaminodiphenyl methane. Aging at high temperatures is accompanied by a pronounced increase in sorptive capacity at 40°C consistent with a significant expansion of the network. Dry annealing of the aged network at sub- T_g temperatures collapses the expanded structure to recover the sorptive capacity of the unaged network. Preliminary studies of the sorption-desorption kinetics for aged networks indicate that the effective diffusion coefficient is not markedly affected.     

不同竹笋粉添加量的面团特性及面包品质的变化

竹笋含有丰富的营养成分。为了探讨竹笋粉对面团和面包品质影响,该研究把竹笋粉以不同添加量（0%、3%、5%、7%,m/m）加入到小麦粉中制作成面包,对面团面筋蛋白、面包色泽、感官、质构特性和贮藏性进行测定。结果表明：随着竹笋粉添加量的增加,面团面筋蛋白含量降低,面包硬度和咀嚼性均提高。低剂量竹笋粉的添加（3%~5%）对面团的pH值和面筋含量影响不显著（P>0.05）,但添加量为7%时湿面筋含量相对下降了9.87%,影响显著。竹笋粉添加与面包的比容和失水率呈负相关,空白组、添加量3%、5%、7%（m/m）的失水率分别为2.45%、2.09%、2.17%、1.77%,其硬度、胶着性、弹性以及咀嚼性变化显著（P<0.05）,对内聚性、回复性影响不显著（P>0.05）。添加竹笋粉（3%~5%）可以提升面包的色泽,使面包具清香风味,但7%的添加量使面包的色泽过深,气味较浓。说明低剂量（3%~5%）的竹笋粉添加制备面包,可提升面包咀嚼感,亮色、丰富其营养成分,还起到延缓面包老化作用。     

老化窖泥复活与壮大的研究

窖泥的质量与酒质酒量有密切关系,但是中国白酒企业从北到南,窖泥使用过程中均出现不同程度老化,老化窖泥无法继续循环使用。通过对老化窖泥复活与壮大的研究,在已经老化的窖泥中加入富含己酸菌液的复活剂,以补充窖泥中优势微生物菌群。实验结果酒中主体呈香呈味物质己酸乙酯的增幅较大。总酸总酯及品评分值均有所提高,口感更协调、柔和,但也有一定的辛辣味。