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981.
One form of damage to automotive painted plastic composites, in particular thermoplastic bumpers and fascias, is known to be caused from compressive shear loading placed on the surface of the composite. The loading inflicted upon the composite by a stationary force (e.g. an automobile hitting a post) or a moving object (e.g. an automobile hitting another automobile), and consequent compressive shear that is induced, can result in cohesive delamination of the substrate. The cohesive delamination in the painted composite (herein referred to as ‘gouge') is not only influenced by the cohesive strength of the substrate but also by the mechanical properties of the coating. Our studies indicate that one important attribute of the coating, namely the coating's coefficient of friction, can significantly impact the ‘gouge' resistance of the painted composite. In this work, we will describe the derivation of coating attributes as they affect ‘gouge' resistance and relate changes in the coating chemistry to useful life parameters. 相似文献
982.
Isotope tracer experiments prove the role of methyl in the oxidative coupling of methane and disprove a recently proposed mechanism involving methylene. The ethane product from oxidative coupling of CH4/CD4 mixtures over a Li/MgO catalyst consists of C2H6, C2D6 and CH3CD3 thus proving that ethane is formed by combination of methyl intermediates. The co-reaction of labelled CH4 (D and13C) with C2H4 produces propylene labelled predominantly at the methyl (3) position, thus proving C3 formation by terminal addition of methyl to ethylene rather than via a cyclic intermediate as has been proposed. 相似文献
983.
The enzymology of sludge solubilisation utilising sulphate-reducing systems: the properties of lipases 总被引:4,自引:0,他引:4
The first stage in the degradation and recycling of particulate organic matter is the solubilisation and enhanced hydrolysis of complex polymeric organic carbon structures associated with the sulphidogenic environment. An investigation into the enzymology of these processes has shown that lipase enzyme activities were found predominantly associated with the organic particulate matter of the sewage sludge. Sonication of the sludge gave an increase in enzyme activity as the enzymes were released into the supernatant. pH and temperature optimisation studies showed optima between 6.5 and 8 and 50-60 degrees C, respectively. All the lipase enzymes from the methanogenic bioreactors indicated extensive stability for at least an hour at their respective optimum temperatures and pH; sulphidogenic lipases reflected limited stability at these temperatures and pH during this time period. Though sulphate showed inhibitory properties towards lipases both sulphide and sulphite appeared to enhance the activity of the enzymes. It is argued that these sulphur species, liberated at different times during the sulphate reduction process, disrupt the integrity of the organic particulate floc by neutralising acidic components on the surface. The release of further entrapped enzymes from the organic particulate matter result in a subsequent enhancement of hydrolysis of polymeric material. 相似文献
984.
Detection of mortality clusters associated with highly pathogenic avian influenza in poultry: a theoretical analysis 下载免费PDF全文
Nicholas J Savill Suzanne G St. Rose Mark E.J Woolhouse 《Journal of the Royal Society Interface》2008,5(29):1409-1419
Rapid detection of infectious disease outbreaks is often crucial for their effective control. One example is highly pathogenic avian influenza (HPAI) such as H5N1 in commercial poultry flocks. There are no quantitative data, however, on how quickly the effects of HPAI infection in poultry flocks can be detected. Here, we study, using an individual-based mathematical model, time to detection in chicken flocks. Detection is triggered when mortality, food or water intake or egg production in layers pass recommended thresholds suggested from the experience of past HPAI outbreaks. We suggest a new threshold for caged flocks—the cage mortality detection threshold—as a more sensitive threshold than current ones. Time to detection is shown to depend nonlinearly on R0 and is particularly sensitive for R0<10. It also depends logarithmically on flock size and number of birds per cage. We also examine how many false alarms occur in uninfected flocks when we vary detection thresholds owing to background mortality. The false alarm rate is shown to be sensitive to detection thresholds, dependent on flock size and background mortality and independent of the length of the production cycle. We suggest that current detection thresholds appear sufficient to rapidly detect the effects of a high R0 HPAI strain such as H7N7 over a wide range of flock sizes. Time to detection of the effects of a low R0 HPAI strain such as H5N1 can be significantly improved, particularly for large flocks, by lowering detection thresholds, and this can be accomplished without causing excessive false alarms in uninfected flocks. The results are discussed in terms of optimizing the design of disease surveillance programmes in general. 相似文献
985.
Michel J.A.M. van Putten Christoph Fahlke Karl W. Kafitz Jeannette Hofmeijer Christine R. Rose 《International journal of molecular sciences》2021,22(11)
Ischemic stroke is a leading cause of mortality and chronic disability. Either recovery or progression towards irreversible failure of neurons and astrocytes occurs within minutes to days, depending on remaining perfusion levels. Initial damage arises from energy depletion resulting in a failure to maintain homeostasis and ion gradients between extra- and intracellular spaces. Astrocytes play a key role in these processes and are thus central players in the dynamics towards recovery or progression of stroke-induced brain damage. Here, we present a synopsis of the pivotal functions of astrocytes at the tripartite synapse, which form the basis of physiological brain functioning. We summarize the evidence of astrocytic failure and its consequences under ischemic conditions. Special emphasis is put on the homeostasis and stroke-induced dysregulation of the major monovalent ions, namely Na+, K+, H+, and Cl−, and their involvement in maintenance of cellular volume and generation of cerebral edema. 相似文献
986.
Essam R. EL-Zahar Mohamed. A. Mansour A. M. Rashad Hamed A. EL-Mky Amal. M. A. EL-Hakiem 《亚洲传热研究》2021,50(7):6425-6443
The intent of the current investigation is to explore the axisymmetric flow of the micropolar nanoliquid past an orthogonal cylinder in the existence of mixed convection impact. Suitable similitude changes produce joined nonlinear differential schemes, which were explicated via fourth-order finite difference style. The authenticity of the results was emphasized by contrasting them with previous results with some limited presumptions and uncovered to be in excellent agreement. Performance of numerous physical parameters on velocity components and temperature distributions alongside the physical quantities of interests were revealed graphically and in tabular forms. It was shown that the skin friction and heat transport rate boost with rising in the volume fraction nanoparticle and the buoyancy, while they decline with the increase of micropolar parameter. This investigation intends to improve on an intuitive understanding of similar patterns by confirming the physical debates and may be applicable in the field of biomechanics, polymer processing, production of aerosol deposition, and thermal treatment. 相似文献
987.
988.
Julius Juma Okello Felix Mwala Shiundu Janet Mwende Carl Johan Lagerkvist Rose Adhiambo Nyikal Penina Muoki John Mburu Jan Low Guy Hareau Simon Heck 《International Journal of Food Science & Technology》2021,56(3):1432-1446
This 2018 study, conducted in six Tusky's supermarkets in Nairobi, Kenya, combined the Just-About-Right, Penalty and Mean-End-Chain analyses to examine the quality and psychosocial factors influencing the purchase of a novel bread made from orange-fleshed sweet potato (OFSP), a biofortified crop, focusing on sixty-one male and eighty female urban OFSP bread buyers recruited at point of purchase. It finds that sensory and psychosocial factors drive purchasing decisions and that some of the bread's sensory characteristics are misaligned with consumers' expectations. It also finds that women and men’s evaluations of the bread's characteristics are different, as are their motivations for purchase. However, good sensory attributes and the knowledge of the bread's nutritional value were key drivers. Some misaligned characteristics reveal levers for the reformulation of the bread and present opportunities for segmenting the market. Several other implications of the findings for policy and future improvement of the bread are discussed. 相似文献
989.
Hafsa Amal Sghaier Anissa Malek Jihene Machhout Mohsen 《Multimedia Tools and Applications》2021,80(13):19769-19801
Multimedia Tools and Applications - Currently, embedded systems can be found everywhere in quotidian life. In the development of embedded systems, information security is one of the important... 相似文献
990.
Al‑Alotaibi Amal L. Altamimi N. Howsawi E. Elsayed Khaled A. Massoudi Imen Ramadan A. E. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(9):3904-3904
Journal of Inorganic and Organometallic Polymers and Materials - A correction to this paper has been published: https://doi.org/10.1007/s10904-021-02038-6 相似文献