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Monodispersed ligand-capped TiO2 nanocrystals are synthesized by a low temperature solvothermal method using oleic acid (OA) as the capping agent. The single layer hybrid films based on the OA-capped TiO2 nanocrystals and poly(9,9-dihexylfluorene) (PFH) are prepared by solution processing at room temperature and characterized by atomic force microscopy, UV-vis absorption and photoluminescence spectra. The hybrid film is applied in the fabrication of nanostructured UV-A photodetector (320-420 nm) by sandwiching it between two electrodes to form bulk heterojunction. The high ultraviolet signal-to-noise ratio of 3 orders of magnitude with short response time less than 200 ms can be achieved for the device. Furthermore, the device shows drastic changes in current under a wide range of UV irradiation with a linear relationship between them. The thermal behavior of the device is also discussed. The high photosensitivity in the UV-A range and the low-cost endow them with potential for environmental and biological uses. 相似文献
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This study investigated the influence of verbal self-instructions (VSI) on the transfer of task-switching training in older adults (56–78 years). We applied an internally cued switching paradigm in a pretest–training–posttest design. Training-related improvements were not modulated by VSI. Transfer (the pretest–posttest reduction of switch costs) was most pronounced when participants applied the VSI at posttest after practicing the switching task without VSI. The results indicate that in contrast to transfer of executive control training, transfer of (verbal) strategy training seems to be limited and that VSI is most beneficial when the task-switching abilities are already well practiced. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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M. Jaureguiberry M.J. Giuliodori A.V. Mang L.V. Madoz H. Pothmann M. Drillich R.L. de la Sota 《Journal of dairy science》2017,100(4):3083-3085
The objective of the present study was to test the association between the presence of fluid in uterine lumen and the fertility of repeat breeder cows (RBC). Grazing Holstein cows that were clinically normal and were not pregnant after at least 3 consecutive inseminations were defined as RBC and included in the study (n = 358). A cut-point ≥2 mm of uterine lumen visible by ultrasonography was used as indicative of the presence of fluid in the uterus. The effect of this fluid on the fertility of RBC was assessed by mixed logistic regression. Twenty percent of the RBC had ≥2 mm of fluid in their uterus, and this finding was associated with a marked reduction in the odds of conception (odds ratio = 0.46). Additional intrauterine sampling revealed that 24.0% of RBC showed signs of subclinical endometritis [≥5% neutrophils in endometrial cytology (SCE)]. However, we found no agreement between the finding of uterine fluid and the diagnosis of SCE (kappa coefficient = 0.03, 95% confidence interval = ?0.07 to 0.14). In conclusion, the presence of fluid (≥2 mm) in uterine lumen, detected by ultrasonography, was associated with lower fertility in RBC, but was not related to the diagnosis of SCE. Thus, ultrasonographic evaluation is an important tool to assist in assessment of RBC. 相似文献
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本文讨论了烯丙基类端基聚氧乙烯(PEO)大单体与苯乙烯进行自由基型以及阳离子型的共聚。采用BF_3·(OC_2H_5)_2催化体系进行PEO大单体与苯乙烯阳离子共聚时,所得共聚物具有较自由基引发体系为高的接枝数,但共聚产率仍相对较低。采用Al(C_2H_5)_3为催化剂或采用甲基烯丙基为端基的PEO大单体为中间体时,所得共聚物具有更大的接枝数和高的产率。 相似文献
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实现两种基于无结构Delaunay三角网格的自适应方法,并且把两种方法分别应用于求解一个典型的二维溃坝问题,同时对两种方法的数值结果和稳定性进行比较。数值结果表明两种方法对提高数值解的精度和调整问题求解区域的剖分起到明显的作用。 相似文献
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Herbert A. Mang Gerhard Höfinger Xin Jia 《Computer Methods in Applied Mechanics and Engineering》2011,200(13-16):1558-1567
The scientific motivation for this paper is lack of clarity about the interdependency of primary and initial secondary equilibrium paths in the frame of sensitivity analysis of elastic structures. The investigation of this interdependency comprises of the following four cases: (1) nonlinear primary path, nonlinear stability problem, (2) linear primary path, nonlinear stability problem, (3) nonlinear primary path, linear stability problem, and (4) linear primary path, linear stability problem. The consistently linearized eigenproblem is used for differentiation of two classes of nonlinear stability problems with markedly different characteristics of both the prebuckling and the postbuckling behavior. For one of them, e.g. zero-stiffness postbuckling is impossible. For the other one, which is restricted to a prebuckling regime with axial deformations only, sensitivity analysis of the initial postbuckling behavior either exhibits its continuous improvement or its continuous deterioration, depending on whether the bifurcation point diverges from or converges to the snap-through point. In other words, a monotonic variation of the design parameter cannot result in a non-monotonic change of the initial postbuckling behavior. The practical motivation for this work is to explore the mechanical reasons for qualitatively different modes of transition from imperfection sensitivity to insensitivity in the course of sensitivity analysis for the purpose of improving the postbuckling behavior of structures by means of minor design changes. Results from a numerical investigation corroborate the theoretical findings. 相似文献