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991.
JK Ma BY Hikmat K Wycoff ND Vine D Chargelegue L Yu MB Hein T Lehner 《Canadian Metallurgical Quarterly》1998,4(5):601-606
The effect of a temperature increase to 52 degrees C or the addition of ethanol (6%) to an exponential Escherichia coli culture on putrescine and potassium transport was studied. The first stage of heat shock was accompanied by a decrease in the extent of DNA supercoiling, due to the dissociation of the putrescine-DNA complex. The loss of potassium ions at this phase produced a synergistic effect. The second phase of the heat shock was characterized by a reversal in the direction of putrescine and potassium transport, which was accompanied by restoration of the prestress extent of DNA supercoiling. An increase in the ATP pool and cell energy charge resulting from the uncoupling of the energy metabolism and synthetic processes also played an important role in the restoration of the DNA initial topology at the second phase of the heat shock via the activation of the energy-dependent gyrase or the heat shock protein DnaK. A mechanism is suggested that explains the involvement of putrescine in the regulation of DNA topology, which is a universal regulator of gene expression under stress, heat shock in particular. 相似文献
992.
R Lehner MM Maassen H Leysieffer D Plester HP Zenner 《Canadian Metallurgical Quarterly》1998,46(1):27-37
OBJECTIVE: The present study sought to examine the validity and utility of diagnostic criteria for binge-eating disorder (BED) by replicating and extending a study reported by de Zwaan and colleagues (International Journal of Eating Disorders, 15, 43-52, 1994). METHOD: Four groups of obese individuals were selected from a large community-based sample of men and women: 33 women and 20 men with BED, 79 women and 40 men with subthreshold BED, 21 women and 39 men who reported recurrent overeating, and 80 female and 80 male normal controls. The groups were compared on measures of body image concern, dieting behavior, and associated psychological distress. RESULTS: Individuals with BED were distinguishable from overeaters and normal controls on a number of psychological and behavioral variables. Few differences were found between subthreshold and full-syndrome BED, raising questions about the diagnostic validity of the frequency threshold. Men with BED did not differ from women with BED above and beyond the gender-related differences observed across all four groups. DISCUSSION: Our findings support the view of BED as a distinct syndrome. 相似文献
993.
Qi Sheng Wendy Tian Florian Lapierre Song Gao Roger J. Mulder Yonggang Zhu Karen A. Kozielski Colin D. Wood 《应用聚合物科学杂志》2014,131(12)
This study introduces a radical‐free approach for generating polyacrylamide (PAM) hydrogels with no toxic residues remaining in the networks. Acrylamide and bisacrylamide, which are neurotoxins, are not used during the hydrogel synthesis and only nontoxic side products are generated. This is achieved using a gentle carbodiimide‐mediated crosslinking (CMCL) reaction that does not require complex initiation systems and is effective in the presence of oxygen. This overcomes some of the key limitations related to PAM hydrogel synthesis using free‐radical routes and maintains the advantages of synthetic hydrogels over biopolymers. In addition, the CMCL reaction allows for accurate placement of functional groups, which controls hydrogel structure and performance including mechanical strength, swelling capacity, and hydrophobic balance. This flexibility is demonstrated through the synthesis and rheological characterization of a library of structurally diverse hydrogels as well as spherical hydrogels. PAM‐based hydrogels are used extensively in a broad number of applications, and this study demonstrates the applicability of this method as a nontoxic and radical‐free complementary alternative route that can generate structures analogous to those prepared using free‐radical routes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40416. 相似文献
994.
Two maize flours (standard and waxy grades) were plasticized in an internal mixer with a constant amount of water and two glycerol contents. The resulting thermoplastic flours (TPFs) were characterized in dynamic oscillatory shear and creep/recovery rheometry. They displayed two different behaviors: the viscoelastic behavior of a high‐molecular‐weight polymer for the first one and a gel‐like behavior for the second one. The TPFs were then mixed with a copolyester [poly(butylene adipate–terephtalate)]. All of the blends contained the same volume fractions and were prepared with the same mixing conditions. The morphology and rheological behavior of each blend were characterized. Different morphologies, ranging from cocontinuous to nodular, were observed. In fixed mixing conditions, the blend morphology was shown to be governed by the rheological behavior of the starchy phase and the plasticizer content. The gel‐like behavior of the second TPF seemed to prevent droplet coalescence; this led to a very fine dispersion. The rheological behavior of each blend appeared to be linked to both the morphology and the rheological behavior of the two phases. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40222. 相似文献
995.
Back Cover: The Integrin Ligand c(RGDf(NMe)Nal) Reduces Neointimal Hyperplasia in a Polymer‐Free Drug‐Eluting Stent System (ChemMedChem 7/2014)
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996.
Blend uniformity and powder phenomena inside the continuous tumble mixer using DEM simulations
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Powder mixing is an essential operation in pharmaceutical, food, and petrochemical industries. Pharmaceutical companies have been working in the implementation of continuous processes as an alternative to the batch process using the food and drug administration process analytical technology initiative. The main goal was to understand the mixing phenomena inside the continuous tumble mixer and monitor blend uniformity using discrete element method. Results demonstrated that the main mixing mechanism is convection similar to the common tumbling mixers. This mechanism is driven by the bulk flow of the particles, due to the mixer rotation. The simulations' results, demonstrated that the cohesion reduces the concentration variability due to the higher holdup, particle interactions, and mean residence time. The blend uniformity at the exit of the system was measured and a relationship between relative standard distribution, cohesion, and the collision frequency was found. © 2014 American Institute of Chemical Engineers AIChE J, 61: 792–801, 2015 相似文献
997.
Florian Koch 《International Planning Studies》2015,20(4):407-423
During the last several years a dynamic transformation has been taking place at the northern city fringe of Barranquilla, Colombia: shopping malls, gated communities and gated tower buildings have been built — a process very similar to other Latin American cities. The aim of this article is to reveal the underlying planning approaches and explain the role and influence of the private and public actors involved. This work contributes to the discussion on formal and informal practices of urban development in the global South and shows the blurring borders between the ‘formal’ and the ‘informal’. The main finding of the analysis is the coherence between the interests of the landowning company, the official land-use plan and the actually implemented projects. This coherence was achieved through the massive influence of private interests in public planning and a multitude of informal arrangements between the landowner and the public authorities. This form of urban planning is described as ‘arranged urbanism’ and stands in a tradition of similar forms of spatial development in Latin America. Nevertheless, forms of ‘arranged urbanism’ can also be found outside of the Latin American context. 相似文献
998.
Ignasi Burgués‐Ceballos Florian Machui Jie Min Tayebeh Ameri Monika M. Voigt Yuriy N. Luponosov Sergei A. Ponomarenko Paul D. Lacharmoise Mariano Campoy‐Quiles Christoph J. Brabec 《Advanced functional materials》2014,24(10):1449-1457
Replacing halogenated solvents in the processing of organic solar cells by green solvents is a required step before the commercialization of this technology. With this purpose, some attempts have been made, although a general method is yet to be developed. Here, the potential of the Hansen solubility parameters (HSP) analysis for the design of green ink formulations for solution‐processed active layer in bulk heterojunction photovoltaic devices based on small molecules is demonstrated. The motivation of moving towards organic small molecules stems from their lower molecular weight and more definite structure which makes them more likely to be dissolved in a wider variety of organic solvents. In the first step, the HSP of selected active materials are determined, namely, the star‐shaped D‐π‐A tris{4‐[5′′‐(1,1‐dicyanobut‐1‐en‐2‐yl)‐2,2′‐bithiophen‐5‐yl]phenyl}amine N(Ph‐2T‐DCN‐Et)3 small molecule and fullerene derivative [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC70BM). Secondly, computer simulations based on HSP allow the prediction of suitable green solvents for this specific material system. The most promising green solvents, according to the simulations, are then used to fabricate solar cell devices using pristine solvents and two solvents mixtures. These devices show power conversion efficiencies around 3.6%, which are comparable to those obtained with halogenated solvents. This good performance is a result of the sufficient solubility achieved after a successful prediction of good (green) solvents. 相似文献
999.