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排序方式: 共有1026条查询结果,搜索用时 15 毫秒
51.
María L Auad Tara Richardson William J Orts Eliton S Medeiros Luiz HC Mattoso Mirna A Mosiewicki Norma E Marcovich Mirta I Aranguren 《Polymer International》2011,60(5):743-750
Segmented polyurethanes exhibiting shape memory properties were modified by the addition of polyaniline (PANI)‐coated cellulose nanofibrils (CNFs). The two‐phase structure of the polymer is responsible for the material's ability to ‘remember’ and autonomously recover its original shape after being deformed in response to an external thermal stimulus. PANI was grown on the surface of the CNFs via in situ polymerization. Modified nanocrystals were added to the segmented polyurethane in concentrations ranging from 0 to 15 wt%. The changes in the material properties associated with the percolation of the coated fibrils appear at higher concentrations than previously observed for non‐modified CNFs, which suggests that fibril agglomeration is occurring due to the PANI coating. The shape memory behavior of the composites is maintained at about the same level as that of the unfilled polyurethane only up to 4 wt% of fibrils. At higher concentrations, the rigidity of the nanofibrils as well as their interaction with the hard‐segment phase and the increasing difficulty of dispersing them in the polymer collaborate to produce early breakage of the specimens when stretched at temperatures above the melting point of the soft segments. Copyright © 2010 Society of Chemical Industry 相似文献
52.
The present paper discusses the role of cabs and the presence of other men in the cab in manufacturing respectability for
the unmarried women agents of call centers in India. The night shift, an intrinsic part of work, at call centers in India
demands mobility and access to public space during nights for its women employees. The paper elaborates how the relation between
gender and space is evolving in the backdrop of the presence of someone trusted, through a shift from private patriarchy to
public patriarchy for the women agents while accessing the public space. The paper is based on a total of sixty-one qualitative
interviews conducted with unmarried women call center employees and parents based in Gurgaon, India. 相似文献
53.
Andrea Gabriellini Matteo Naccari Marta Mrak David Flynn Glenn Van Wallendael 《Signal Processing: Image Communication》2013,28(3):197-208
New generations of video compression algorithms, such as those included in the under development High Efficiency Video Coding (HEVC) standard, provide substantially higher compression compared to their ancestors. The gain is achieved by improved prediction of pixels, both within a frame and between frames. Novel coding tools that contribute to the gain provide highly uncorrelated prediction residuals for which classical frequency decomposition methods, such as the discrete cosine transform, may not be able to supply a compact representation with few significant coefficients. To further increase the compression gains, this paper proposes transform skip modes which allow skipping one or both 1-D constituent transforms (i.e., vertical and horizontal), which is more suitable for sparse residuals. The proposed transform skip mode is tested in the HEVC codec and is able to provide bitrate reductions of up to 10% at the same objective quality when compared with the application of 2-D block transforms only. Moreover, the proposed transform skip mode outperforms the full transform skip currently investigated for possible adoption in the HEVC standard. 相似文献
54.
Abstract. This paper presents a commitment transformation framework for analysing the change in actors' commitment during the transition from escalation to de-escalation in information technology projects. De-escalation is potentially a more important issue than escalation because de-escalation provides remedies for the ills of escalation. Therefore, it is important to understand how stakeholders may bias facts in the direction of previously accepted beliefs and thus prevent an organization from de-escalating. Here, we adopt Lewin's change theory to examine the commitment transformation during the transition from escalation to de-escalation of an e-government project in a local council in the United Kingdom. By conceiving actors' commitment transformation as an 'unfreezing–changing–refreezing' process, researchers may develop a deeper understanding of how actors may give up previous failing course of action and accept an alternative course of action. Practitioners can also utilize the framework in post-mortem analyses of projects which have faced escalation to devise useful de-escalation strategies for future project development. 1 相似文献
55.
56.
Twomey DP Wheelock AI Flynn J Meaney WJ Hill C Ross RP 《Journal of dairy science》2000,83(9):1981-1988
We assessed the effectiveness of a novel dry cow treatment containing lacticin 3147 using deliberate challenge studies in lactating cows. Infection-free quarters of lactating cows were infused with Teat seal (Cross Vetpharm Group, Ltd., Dublin, Ireland) combined with the food-grade bacteriocin, lacticin 3147. Natural infection of the teat was simulated by deliberately introducing Staphylococcus aureus into the teat duct and teat sinus. Relative to control quarters, teat seal plus lacticin 3147 reduced the number of teats shedding viable cells when an inoculum of either approximately 1.7 x 10(3) or approximately 6.8 x 10(3) cfu per teat was used. In addition, the numbers of challenge organisms in those teats from which S. aureus was subsequently recovered were also reduced. However, when the concentration of bacteriocin in the teat seal formulation was reduced by approximately 50%, the number of teats shedding S. aureus cells was not reduced. These data indicate the potential for lacticin 3147 to prevent staphylococcal mastitis infections when a sufficient concentration of the bacteriocin is present. This study also highlights the application of a lactating-cow model to assess the effectiveness of antimicrobial intramammary products on mastitic cell populations. 相似文献
57.
It is argued that psychologists, through activities related to program evaluation, can make contributions to at least four pressing issues: participation in and formulation of public policy regarding rehabilitation; clarification of the nature and scope of rehabilitation itself; practice of theory-driven evaluation; and the cumulation of knowledge through meta-analytic methods. Papers in the Special Issue are briefly introduced and described. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
58.
Y Qian JM Baisden EH Westin AC Guappone TC Koay DC Flynn 《Canadian Metallurgical Quarterly》1998,16(17):2185-2195
The SH2 and SH3 binding partner AFAP-110 is a tyrosine phosphorylated substrate of Src. AFAP-110 has been hypothesized to link Src to actin filaments, which may contribute to the effects of Src upon actin filament integrity. However, it has been unclear what effect activated Src (Src527F) has upon AFAP-110 structure or function and whether AFAP-110 plays a role in actin filament integrity. We report here that the carboxy terminal 127 amino acids of AFAP-110 are comprised of an alpha-helical region that contains a leucine zipper motif. This indicated the potential of AFAP-110 to self-associate. Expression of the carboxy terminus as a fusion protein (GST-cterm) will permit affinity absorption of cellular AFAP-110. The integrity of the alpha-helical leucine zipper motif in GST-cterm is required for affinity absorption, but binding is not due to a classical leucine zipper interaction. Co-expression of Src527F, unlike cSrc, will abrogate affinity absorption of AFAP-110 with GST-cterm. These data indicate that Src527F has affected a change in the carboxy terminal structure that renders AFAP-110 unavailable for affinity absorption. Superose chromatography demonstrate that AFAP-110 will fractionate as a monomer or multimer, indicating AFAP-110 can be detected in a self-associated form in cell lysates. Co-expression of Src527F resulted in AFAP-110 fractionating with a molecular weight that predicts only a multimeric population. Deletional mutagenesis also indicate a biological role for the carboxy terminus in cellular localization and actin filament integrity. Deletion of the entire carboxy terminal alpha-helix (84 amino acids) will not permit AFAP-110 to efficiently colocalize with actin filaments or the cell membrane. Deletion of only the leucine zipper region of the carboxy terminal alpha-helix (44 amino acids) from AFAP-110 (AFAPAdeltazip) demonstrate that both AFAPdeltalzip and actin filaments are repositioned into rosette-like structures, similar to the effects of Src527F, while co-expression of AFAP-110 with cSrc will not affect actin filaments. These data indicate that AFAP-110 can play an important role in modulating actin filament integrity through carboxy terminal interactions that can be affected by Src527F. 相似文献
59.
60.
We studied a 14-year-old girl who suffered fractures of her mandible and tegmen following a fall from a balance beam. Thirteen days after hospitalization, she developed severe, protracted, recurrent episodes of hyperventilation; subsequently, she suffered posthyperventilation apnea, which at times was prolonged and association with severe hypoxemia with an arterial oxygen pressure as low as 25 mm Hg. The patient was treated with added dead space and chlorpromazine hydrochloride (Thorazine). Postulated mechanisms for her disorder are discussed. The importance of close clinical and laboratory observation in similar cases is stressed. 相似文献