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101.
Rocco P. Viggiano III Edward E. Ball Ronald E. Park Karl W. Haider David A. Schiraldi 《应用聚合物科学杂志》2015,132(39)
The feasibility of incorporating ground recycled polyurethane (PU) foam into clay/polymer aerogels was demonstrated, and a range of compositions were prepared and characterized to determine the effect of variation in the formulations on density and mechanical properties of the resulting materials. This study followed a modified combinatorial approach. Initially, experiments were performed in water using either sodium exchanged montmorillonite or laponite clay, poly(vinyl alcohol) (PVOH) solution as the polymer binder, and the recycled PU foam. Freezing and freeze‐drying the aqueous gels produced aerogels, which were characterized through density and mechanical testing, scanning electron microscopy, and thermal gravimetric analysis. The study was expanded by exploring alternative binder chemistries, including the use of an alginate polymer in place of the PVOH or adding a polyisocyanate as a crosslinking agent for PVOH. The effect of recycled PU foam content, clay type and level, and binder type and level on the mechanical properties of the aerogels were determined and will be discussed herein. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42586. 相似文献
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104.
Karl Becker 《化学,工程师,技术》2016,88(8):1031-1049
Focus of the two preceding papers within this publication series were the development and manufacturing of technical catalysts at the Leuna Werke company from 1921 – 1945 (part I) and 1950 – 1991 (part II) for the reforming and isomerization catalysts. This article describes the genesis of the hydrofining group of catalysts as cornerstones of the GDR economy. 36 catalysts and 15 special aluminum oxides, X‐ray amorphous as well as crystalline aluminum silicates, were developed and brought into service for the Leuna hydrogenation and other refineries. During that time, a vast knowledge base was generated; new chemical processes were pioneered and equipped with tailor‐made catalysts developed in Leuna. 相似文献
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106.
Grigor B. Bantchev Kenneth M. Doll Girma Biresaw Karl E. Vermillion 《Journal of the American Oil Chemists' Society》2014,91(12):2117-2123
Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2‐ethylhexanol, benzyl alcohol, in the presence of Brønsted acid catalyst, were investigated. Products, not reported in prior studies of similar reactions, were found. These were furan fatty acid alkyl esters (FFE, mixture of alkyl 8‐(5‐hexyl‐2‐furyl) octanoate and alkyl 9‐(5‐pentyl‐2‐furyl)nonanoate) which were unambiguously identified by means of GC–MS and two‐dimensional NMR. Evidence suggests that the FFE are formed by an acid‐catalyzed rearrangement of the epoxidized linoleates. The FFE were formed in presence of all four alcohols tested and in the presence of either sulfuric acid or Amberlyst 15 catalyst. Yields of up to 13 %, as quantified by GC and NMR spectroscopies, were observed. 相似文献
107.
A series of model polytetrahydrofuran (PTHF) networks were synthesized via end-linking reactions of α, ω-allyl PTHF oligomers with a stoichiometric tetrafunctional crosslinker. The telechelic PTHF oligomers were synthesized by living cationic ring-opening polymerization of tetrahydrofuran followed by a termination reaction with allyl alcohol. Networks thus prepared have well-controlled architecture in terms of the inter-crosslink chain length (Mc) and chain length distribution: resulting in unimodal, bimodal and clustered structures. Unimodal network was prepared by using polymer chains of same molecular weight, bimodal networks were synthesized by using two groups of polymer chains with different average molecular weights, and the clusters are prepared by incorporating clusters of networks with small molecular weight chains in a network matrix made of longer chains. Thermal characteristics of these model networks were investigated as a function of crosslink density, as well as inhomogeneities of crosslink distribution using DSC. We demonstrate that glass transition temperature (Tg) and crystallization behavior (melting temperature and crystallinity) of the networks are both strongly influenced by crosslink density (Mc). By comparing the unimodal, bimodal and clustered networks with similar average Mc, the effects of inhomogeneities in the crosslink distribution on the thermal properties were also investigated. Results show that inhomogeneities have trivial influence on Tg, but strongly affects the crystallization behavior. Moreover, the effects of the content ratio and length ratio between long and short chains, and the effects of cluster size and size distribution on the thermal characteristics were also studied. 相似文献
108.
Yuliya Voronko Gabriele C. Eder Marlene Knausz Gernot Oreski Thomas Koch Karl A. Berger 《Progress in Photovoltaics: Research and Applications》2015,23(11):1501-1515
The influence of the type of backsheet on the electrical performance of test modules was evaluated before and after increasing time of accelerated ageing (damp heat [DH] exposure). Besides the measurement of the electrical power of the modules and the performance of the cells by electroluminescence, the ageing‐induced changes within the polymeric encapsulate and backsheets were investigated by means of vibrational spectroscopy and by thermo analytical methods. In addition, the permeability of the backsheets in the original and aged state was determined. This wide set of test parameters and methods allowed for the detection of correlations between (i) physical and chemical properties as well as their ageing‐induced changes of the materials and (ii) the module performance. A clear dependence of the relative loss in power output upon exposure under DH conditions for 2000 h could be observed for a set of identical test modules varied in composition only in the type of back cover used. While the modules containing gas‐tight backsheets and glass experienced only little loss in the relative power output, some modules with permeable backsheets showed a significant relative decrease in the power output and fill factor in dependence of the backsheet type used. Cell degradation could be visualised by recording electroluminescence images before and after the accelerated ageing test. The permeation properties of the backsheet used and their ageing‐induced changes seem to have an influence on the module performance. However, the absolute values neither of the water vapour transmission rate (WVTR) nor of the oxygen transmission rate (OTR) are directly linked to the loss in power output upon accelerated ageing under DH conditions. It could be shown that the ageing‐induced changes (relative transmission rates) between WVTR and OTR can be correlated with the module performance. These ageing‐induced changes in the permeation behaviour of the backsheets can be explained by (i) physical changes (e.g. post‐crystallisation, changes in the crystal structure or the crystalline microstructure) and (ii) chemical ageing effects such as a decrease in the molecular mass of the polyester (PET) polymer chains because of hydrolytic polymer degradation leading to a change in the crystallisation behaviour of PET. Hydrolytic degradation (= chemical ageing) of the PET core layer was observed (with varying extent) for all PET‐based backsheets and can, thus, not be directly correlated with the loss in performance of the corresponding test modules. The physical ageing effects, however, were detected only for those backsheets showing (i) strong deviating changes in the relative permeation rates for oxygen and water vapour upon accelerated ageing and (ii) a clear loss in electrical performance. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
109.
Eugenia Z. Poh Courtney Green Luca Agostinelli Marissa Penrose-Menz Ann-Kathrin Karl Alan R. Harvey Jennifer Rodger 《International journal of molecular sciences》2022,23(5)
Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique that has the potential to treat a variety of neurologic and psychiatric disorders. The extent of rTMS-induced neuroplasticity may be dependent on a subject’s brain state at the time of stimulation. Chronic low intensity rTMS (LI-rTMS) has previously been shown to induce beneficial structural and functional reorganisation within the abnormal visual circuits of ephrin-A2A5-/- mice in ambient lighting. Here, we administered chronic LI-rTMS in adult ephrin-A2A5-/- mice either in a dark environment or concurrently with voluntary locomotion. One day after the last stimulation session, optokinetic responses were assessed and fluorescent tracers were injected to map corticotectal and geniculocortical projections. We found that LI-rTMS in either treatment condition refined the geniculocortical map. Corticotectal projections were improved in locomotion+LI-rTMS subjects, but not in dark + LI-rTMS and sham groups. Visuomotor behaviour was not improved in any condition. Our results suggest that the beneficial reorganisation of abnormal visual circuits by rTMS can be significantly influenced by simultaneous, ambient visual input and is enhanced by concomitant physical exercise. Furthermore, the observed pathway-specific effects suggest that regional molecular changes and/or the relative proximity of terminals to the induced electric fields influence the outcomes of LI-rTMS on abnormal circuitry. 相似文献
110.
Jiraporn Ousingsawat Raquel Centeio Rainer Schreiber Karl Kunzelmann 《International journal of molecular sciences》2022,23(6)
SLC26A9 is an epithelial anion transporter with a poorly defined function in airways. It is assumed to contribute to airway chloride secretion and airway surface hydration. However, immunohistochemistry showing precise localization of SLC26A9 in airways is missing. Some studies report localization near tight junctions, which is difficult to reconcile with a chloride secretory function of SLC26A9. We therefore performed immunocytochemistry of SLC26A9 in sections of human and porcine lungs. Obvious apical localization of SLC26A9 was detected in human and porcine superficial airway epithelia, whereas submucosal glands did not express SLC26A9. The anion transporter was located exclusively in ciliated epithelial cells. Highly differentiated BCi-NS1 human airway epithelial cells grown on permeable supports also expressed SLC26A9 in the apical membrane of ciliated epithelial cells. BCi-NS1 cells expressed the major Cl− transporting proteins CFTR, TMEM16A and SLC26A9 in about equal proportions and produced short-circuit currents activated by increases in intracellular cAMP or Ca2+. Both CFTR and SLC26A9 contribute to basal chloride currents in non-stimulated BCi-NS1 airway epithelia, with CFTR being the dominating Cl− conductance. In wtCFTR-expressing CFBE human airway epithelial cells, SLC26A9 was partially located in the plasma membrane, whereas CFBE cells expressing F508del-CFTR showed exclusive cytosolic localization of SLC26A9. Membrane localization of SLC26A9 and basal chloride currents were augmented by interleukin 13 in wild-type CFTR-expressing cells, but not in cells expressing the most common disease-causing mutant F508del-CFTR. The data suggest an upregulation of SLC26A9-dependent chloride secretion in asthma, but not in the presence of F508del-CFTR. 相似文献