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11.
Bor‐Sen Chiou Diana Valenzuela‐Medina Mark Wechsler Cristina Bilbao‐Sainz Artur K. Klamczynski Tina G. Williams Delilah F. Wood Greg M. Glenn William J. Orts 《应用聚合物科学杂志》2015,132(10)
Torrefied almond shells and wood chips were incorporated into polypropylene as fillers to produce torrefied biomass‐polymer composites. The composites were prepared by extrusion and injection molding. Response surface methodology was used to examine the effects of filler concentration, filler size, and lignin factor (relative lignin to cellulose concentration) on the material properties of the composites. The heat distortion temperatures, thermal properties, and tensile properties of the composites were characterized by thermomechanical analysis, differential scanning calorimetry, and tensile tests, respectively. The torrefied biomass composites had heat distortion temperatures of 8–24°C higher than that of neat polypropylene. This was due to the torrefied biomass restricting mobility of polypropylene chains, leading to higher temperatures for deformation. The incorporation of torrefied biomass generally resulted in an increase in glass transition temperature, but did not affect melting temperature. Also, the composites had lower tensile strength and elongation at break values than those of neat polypropylene, indicating weak adhesion between torrefied biomass and polypropylene. However, scanning electron microscopy results did indicate some adhesion between torrefied biomass and polypropylene. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41582. 相似文献
12.
Genoveva Buelna Mutlu Ulutagay-Kartin Tina M. Nenoff 《Chemical Engineering Communications》2006,193(5):606-619
Alkylation reactions of benzene with propylene using heterogeneous catalysts H+-β zeolite, MCM-22, and ZSM-5 were studied for their affinity for cumene production. This work focused on the gas-phase reaction using different crystalline catalysts at several temperatures and amounts of reactants using both batch and continuous fixed-bed reactors. The properties of baseline commercial H+-β catalysts versus versions modified with Ga, La, and Pt were studied. Quantitative analysis of product mixture was performed by gas chromatography. For the batch reactor, β-zeolite produced the highest cumene yield and selectivity of 72% and 92%, respectively, at 225°C. At this temperature, a benzene:propylene dilution of 7:1 molar ratio was the optimum. For the continuous system, cumene production is favored at lower space velocities, higher benzene-to-propylene ratio, and temperatures close to 225°C. Ga modification of the H+-β zeolite significantly enhanced cumene yield in the continuous fixed-bed reactor at 225°C, from 27% of the unmodified β-zeolite to 36% for the Ga-modified one. The life span of modified β-catalysts was studied in the fixed-bed reactor for the first eight hours of reaction. 相似文献
13.
Cationic Nanogels: Reduction‐Sensitive Dextran Nanogels Aimed for Intracellular Delivery of Antigens (Adv. Funct. Mater. 20/2015) 下载免费PDF全文
14.
Tina M. Briere Marcel H. F. Sluiter Vijay Kumar Yoshiyuki Kawazoe 《Bulletin of Materials Science》2003,26(1):115-116
The geometries of several Mn clusters in the size range Mn13-Mn{on23} are studied via the generalized gradient approximation to density functional theory. For the 13-and 19-atom clusters, the
icosahedral structures are found to be most stable, while for the 15-atom cluster, the bcc structure is more favoured. The
clusters show ferrimagnetic spin configurations. 相似文献
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Živec Tina Anžur Andreja Verbovšek Timotej 《Bulletin of Engineering Geology and the Environment》2019,78(3):1631-1643
Bulletin of Engineering Geology and the Environment - Terrestrial laser scanning (TLS) was performed in tectonically undisturbed flysch in the Elerji quarry (south-west Slovenia), which represents... 相似文献
17.
Lütke-Eversloh T Fischer A Remminghorst U Kawada J Marchessault RH Bögershausen A Kalwei M Eckert H Reichelt R Liu SJ Steinbüchel A 《Nature materials》2002,1(4):236-240
The development of non-petrochemical sources for the plastics industry continues to progress as large multinationals focus on renewable resources to replace fossil carbon. Many bacteria are known to accumulate polyoxoesters as water-insoluble granules in the cytoplasm. The thermoplastic and/or elastomeric behaviour of these biodegradable polymers holds promise for the development of various technological applications. Here, we report the synthesis and characterization of microbial polythioesters (PTEs), a novel class of biopolymers of general technological relevance. Biosynthesis of PTE homopolymers was achieved using a recombinant strain of Escherichia coli that expressed a non-natural pathway consisting of a butyrate kinase, a phosphotransbutyrylase, and a PHA synthase. Different homopolymers were produced, consisting of either 3-mercaptopropionate, 3-mercaptobutyrate, or 3-mercaptovalerate repeating units, if the respective mercaptoalkanoic acids were provided as precursor substrates to the fermentative process. The PTEs contributed up to 30% (w/w) of the cellular dry weight and were identified as hydrophobic inclusions in the cytoplasm. The chemical and stereochemical homogeneity of the purified PTEs were identified by different methods, and the estimated physical properties were compared to the oxypolyester equivalents, revealing low crystalline order and, for the poly(3-mercaptopropionate) improved thermal stability. The ability to produce PTEs through a biosynthetic route opens up new avenues in the field of biomaterials. 相似文献
18.
Chen Edith; Hermann Cathy; Rodgers Denise; Oliver-Welker Tina; Strunk Robert C. 《Canadian Metallurgical Quarterly》2006,25(3):389
This study tested the relationship of anxiety and asthma severity to symptom perception. Eighty-six children diagnosed with mild or moderate asthma had symptom perception and pulmonary function measured throughout methacholine challenge (to induce bronchoconstriction). Higher trait anxiety was associated with heightened symptom perception (controlling for pulmonary function) at baseline. Greater asthma severity was associated with blunted symptom perception (controlling for pulmonary function) at the end of methacholine challenge and with a slower rate of increase in symptom perception across methacholine challenge. These results suggest that anxiety plays a role when children's symptoms are mild, whereas medical variables such as severity play a role in perception of changes in asthma symptomatology as bronchoconstriction worsens. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Tina Yu 《Genetic Programming and Evolvable Machines》2001,2(4):345-380
We present a novel approach using higher-order functions and abstraction to evolve recursive and modular programs. Moreover, a new term structure abstraction is introduced to describe the property emerged from the higher-order function program structure. We test this technique on the general even-parity problem. The results indicate that this approach is very effective with the general even-parity problem due to the appropriate selection of the foldr higher-order function. Initially, foldr structure abstraction identify the promising area of the search space at generation zero. Once the population is within the promising area, foldr structure abstraction provides hierarchical processing for search. Consequently, solutions to the general even-parity problem are found very efficiently. We identify the limitations of this new approach and conclude that only when the appropriate higher-order function is selected that the benefits of structure abstraction show. 相似文献