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The mechanical properties of composites consisting of high-density polyethylene (HDPE) and oil palm fibrous wastes—that is, empty fruit bunch (EFB)—have been investigated. Tensile modulus showed an increase, whereas tensile strength, elongation at break, and impact strength decreased with increasing filler loading. The strong tendency of EFB to exist in the form of fiber bundles and the poor filler–matrix interaction is believed to be responsible for the poor strength displayed by the composites. Attempts to improve these properties using two types of coupling agents, that is, 3-aminopropyltrimethoxysilane (3-APM) and 3-aminopropyltriethoxysilane (3-APE) and two types of compatibilizers, poly(propylene–acrylic acid) (PPAA) and poly(propylene–ethylene–acrylic acid), (PPEAA), are described. While almost all chemical treatments increased the stiffness of the composites, limited improvement has been observed in the case of tensile strength. This have been attributed to the presence of fiber bundles that remain intact even after several types of chemical treatment have been carried out. Thus, the role of EFB as reinforcing agent is not fully realized. Scanning electron microscopy (SEM) micrographs revealed that the main energy-absorbing mechanisms contributing towards toughness enhancement is through the fiber bundle pull-out process. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2189–2203, 1998 相似文献
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Permyakov Sergei E.; Cherskaya Alexandra M.; Senin Ivan I.; Zargarov Aminullah A.; Shulga-Morskoy Sergey V.; Alekseev Andrey M.; Zinchenko Dmitry V.; Lipkin Valery M.; Philippov Pavel P.; Uversky Vladimir N.; Permyakov Eugene A. 《Protein engineering, design & selection : PEDS》2000,13(11):783-790
A molecule of the photoreceptor Ca2+-binding protein recoverincontains four potential EF-hand Ca2+-binding sites, of whichonly two, the second and the third, are capable of binding calciumions. We have studied the effects of substitutions in the second,third and fourth EF-hand sites of recoverin on its Ca2+-bindingproperties and some other characteristics, using intrinsic fluorescence,circular dichroism spectroscopy and differential scanning microcalorimetry.The interaction of the two operating binding sites of wild-typerecoverin with calcium increases the protein's thermal stability,but makes the environment around the tryptophan residues moreflexible. The amino acid substitution in the EF-hand 3 (E121Q)totally abolishes the high calcium affinity of recoverin, whilethe mutation in the EF-hand 2 (E85Q) causes only a moderatedecrease in calcium binding. Based on this evidence, we suggestthat the binding of calcium ions to recoverin is a sequentialprocess with the EF-hand 3 being filled first. Estimation ofCa2+-binding constants according to the sequential binding schemegave the values 3.7 x 106 and 3.1 x 105 M1 for thirdand second EF-hands, respectively. The substitutions in theEF-hand 2 or 3 (or in both the sites simultaneously) do notdisturb significantly either tertiary or secondary structureof the apo-protein. Amino acid substitutions, which have beendesigned to restore the calcium affinity of the EF-hand 4 (G160D,K161E, K162N, D165G and K166Q), increase the calcium capacityand affinity of recoverin but also perturb the protein structureand decrease the thermostability of its apo-form. 相似文献
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A. K. M. Aminullah Bhulyan W. M. N. Ratnayake R. G. Ackman 《Journal of the American Oil Chemists' Society》1986,63(3):324-328
Fall Atlantic mackerel (Scomber scombrus L.), non-smoked and hot smoked according to the method of Torry (Aberdeen, Scotland) Advisory Note #82, in an AFOS-Torry
Mini Kiln, were used to study changes in oxidative rancidity and composition of major lipid classes and fatty acids. After
smoking there was an increase in thiobarbituric acid (TBAM) value and peroxide (PO) value, but the values were still indicative
of acceptable quality. The percentages of triglycerides (TG) and phospholipid (PL) did not change significantly, and free
fatty acids could barely be detected. The overall fatty acid composition remained virtually unchanged after the smoking process.
This included the longer chain C20 and C22 n-3 fatty acids, now regarded as potentially essential fatty acids for humans. 相似文献
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The growth of Ba0.55Sr0.45TiO3 films on p-type silicon substrate with depletion and enhancement treatments have been conducted in this research. The aims were to examine film sensitivity as light sensor and value range, resolution, acuracy level, and their hysteresis as temperature sensor. The films were annealed at 800, 850, and 900 °C for 15 hours. In this work, enhancement BST of 850 °C was the best quality film and utilized as light and temperature sensors. Its implementation has been successfully conducted on ATMega8535 microcontroller-based automatic drying system model by exploiting the working principle of the BST films as automatic switch. 相似文献
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