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51.
Luis O. Soto-Rojas B. Berenice Campa-Crdoba Charles R. Harrington Andrs Salas-Casas Mario Hernandes-Alejandro Ignacio Villanueva-Fierro Marely Bravo-Muoz Linda Garcs-Ramírez Fidel De La Cruz-Lpez Miguel ngel Ontiveros-Torres Goar Gevorkian Mar Pacheco-Herrero Jos Luna-Muoz 《International journal of molecular sciences》2021,22(7)
Alzheimer’s disease (AD) is a neurodegenerative disease, characterized histopathologically by intra-neuronal tau-related lesions and by the accumulation of amyloid β-peptide (Aβ) in the brain parenchyma and around cerebral blood vessels. According to the vascular hypothesis of AD, an alteration in the neurovascular unit (NVU) could lead to Aβ vascular accumulation and promote neuronal dysfunction, accelerating neurodegeneration and dementia. To date, the effects of insoluble vascular Aβ deposits on the NVU and the blood–brain barrier (BBB) are unknown. In this study, we analyze different Aβ species and their association with the cells that make up the NVU. We evaluated post-mortem AD brain tissue. Multiple immunofluorescence assays were performed against different species of Aβ and the main elements that constitute the NVU. Our results showed that there are insoluble vascular deposits of both full-length and truncated Aβ species. Besides, insoluble aggregates are associated with a decrease in the phenotype of the cellular components that constitute the NVU and with BBB disruption. This approach could help identify new therapeutic targets against key molecules and receptors in the NVU that can prevent the accumulation of vascular fibrillar Aβ in AD. 相似文献
52.
Tjokorde W. Samadhi Linda E. Jones Alexis G. Clare 《Journal of the American Ceramic Society》2003,86(12):2044-2049
Carbon reacts with Na2 SO4 in glass batches, influencing SO x emissions. To study the role of carbon active surface area (ASA) in the decomposition phenomena, Na2 SO4 is reacted with three carbons with a wide ASA range. The decomposition behavior was evaluated by thermogravimetric analysis (TGA) and evolved gas analysis via mass spectrometry and Fourier transform infrared spectrometry. Higher carbon ASA yields lower decomposition temperatures. SO x emissions are realized at temperatures as low as 773 K. Isothermal Na2 SO4 –C decomposition initiates via the nucleation of Na2 S. The rate constants for the nucleation regime are normalized against ASA, yielding an activation energy of 275 kJ/mol for nucleation. 相似文献
53.
A multilayer background modeling technique is presented for video surveillance. Rather than simply classifying all features in a scene as either dynamically moving foreground or long-lasting, stationary background, a temporal model is used to place each scene object in time relative to each other. Foreground objects that become stationary are registered as layers on top of the background layer. In this process of layer formation, the algorithm deals with ”fake objects” created by moved background, and noise created by dynamic background and moving foreground objects. Objects that leave the scene are removed based on the occlusion reasoning among layers. The technique allows us to understand and visualize a scene with multiple objects entering, leaving, and occluding each other at different points in time. This scene understanding leads to a richer representation of temporal scene events than traditional foreground/background segmentation. The technique builds on a low-cost background modeling technique that makes it suitable for embedded, real-time platforms. 相似文献
54.
An experimental study to determine the effect of copper (I) iodide (Cul) on the rate and product distribution of degradation of a model of an aliphatic–aromatic polyamide was carried out. N,N′-Dihexylisophthalamide (DHI) was reacted in both an inert argon atmosphere and a pure oxygen environment at 350°C with CuI added in amounts ranging from 0 to 20% by weight. The rate of disappearance of DHI was enhanced by an order of magnitude when 0.5% by weight of CuI was added and was an increasing function of increasing CuI loading. Reaction in pure O2 increased the rate of DHI degradation by two orders of magnitude over that for neat DHI pyrolysis. The rate of disappearance of DHI in O2 was relatively unchanged when 5% CuI by weight was added. The transformations of DHI and its products are organized in terms of a set of reaction rules. This “reaction operator” formalism allowed computer generation of the reaction network and facilitated estimation of kinetic parameters. © 1995 John Wiley & Sons, Inc. 相似文献
55.
Cellulose fiber surface was modified with silk sericin (or simply, sericin). Sericin fixation on cellulose was confirmed by environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectrophotometry–attenuated total reflectance (FTIR‐ATR). Sericin content in finished samples was estimated by dyeing treated fabrics with an acid dye, Supranol Bordeaux B, and determining K/S and L values of the dyed fabrics. The treated fabrics were tested for free formaldehyde content, crease recovery, tensile strength, electrical resistance, water retention, and biocidal activity. From ESEM and FTIR‐ATR results, it was found that sericin coated onto cotton surfaces as a film. Increasing sericin content in the finishing solution increased the amount of coated sericin, and a greater depth of color in dyed samples and reduced free formaldehyde content in treated samples were observed. The sericin content in samples was found to have a negligible influence on tensile strength and crease recovery angle. With increasing sericin content, electrical resistivity of the samples dramatically decreased and water retention increased, indicating that sericin‐treated fabrics may be comfortable to wear because of its maintenance of moisture balance with respect to human skin. Because cotton textile coated with sericin exhibited low formaldehyde content and no biocidal activity against Klebsiella pneumoniae and Staphylococcus aureus, the fabric may reduce skin irritation and disturbance of physiological skin flora arising from textile contact. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1421–1428, 2005 相似文献
56.
Plastic injection molding machine that can be classified as reciprocating extruders are among the most widely used machines in industry. However, most studies in the injector design were based on steady state models developed for extruders that involved no reciprocation. This over-simplified model leaves out the most important aspect of reciprocation. The authors of this paper have derived a transient melting model that takes care of the change from the conventional steady extrusion to that of a discontinuous transient process. This paper describes simulations conducted on the derived model to explain observation that cannot be explained by the steady extrusion model in practical experiments. The simulation was conducted by using parameters given in Donovan's experiment [Polym Engng, 11 (1971) 353]. The simulation results are found to qualitatively match with the experimental results. It proves the validity of the model. Simulation has also been conducted with the model on materials that their viscosities are temperature and shear rate dependent. The result has shown that screw rotation speed, screw axial movement speed, barrel thickness, barrel heat capacity, temperature of heater and polymer are factors affecting the melting speed and the transient effects. 相似文献
57.
A methylene-interrupted C18 keto-acetylenic fatty ester (methyl 12-oxo-9-octadecynoate) was obtained from methyl ricinoleate by bromination-dehydrobromination
followed by oxidation. Reaction of methyl 12-oxo-9-octadecynoate with bis(benzonitrile) palladium(II) chloride, allyl bromide,
or methyl-allyl bromide furnished methyl 8-[5-hexyl-3-allyl-furan-2-yl]-octanoate (1, 56%) or methyl 8-[5-hexyl-3-(2-methyl-allyl)-furan-2-yl]-octanoate (2, 55%). Reaction of methyl 12-oxo-11-chloro-or 11-fluoro-9-octadeyynoate (prepared from methyl santalbate-methyl 11-E-9-octadecynoate, found in sandalwood, Santalum album, seed oil) with bis(benzonitrile) palladium(II) chloride gave methyl 8-(4-fluoro-5-hexyl-furan-2-yl)-octanoate (3, 50%) or methyl 8-(4-fluoro-5-hexyl-furan-2-yl)-octanoate (4, 50%), respectively. And when methyl 12-oxo-11-chloro- or 11-fluoro-9-octadecynoate was treated with a mixture of bis(benzonitrile)
palladium(II) chloride, allyl bromide, or methyl-allyl bromide, the reaction yielded tetrasubstituted C18 furan derivatives, viz, methyl 8-(3-allyl-4-chloro-5-hexyl-furan-2-yl)-octanoate (5, 54%), methyl 8-[4-chloro-5-hexyl-3-(2-methyl-allyl)-furan-2-yl)-octanoate (6, 54%), methyl 8-(3-allyl-4-fluoro-5-hexyl-furan-2-yl]-octanoate (7, 10%), and methyl 8-[4-fluoro-5-hexyl-3-(2-methyl-allyl)-furan-2-yl]-octanoate (8, 10%). The presence of a fluorine atom in the furan derivatives 4, 7, and 8 was readily characterized by the appearance of doublets for carbon nuclei, which were coupled to the fluorine atom
in the 13C NMR spectra. All furan fatty derivatives from this work were characterized by NMR spectroscopic and mass spectrometric analyses.
The yields of compounds 7 and 8 were very low (10%) despite attempts to improve the procedure by increasing the amounts of the reactants and catalyst. 相似文献
58.
Stephen Scypinski Linda Nelson Theodore Sadlowski 《Journal of Automated Methods and Management in Chemistry》1995,17(2):47-49
It has been over 10 years since robots have appeared in the pharmaceutical analysis laboratory. In the early days, it was common for one selected individual to be responsible for the programming, usage and maintenance of the robots(s). However, the increasing use of robotics has prompted the formation of robotics
‘laboratories’ and/or ‘groups’. This is especially true when
multiple robotic systems and applications are involved.Over the past several years at ISLAR, many champions of robotics have given presentations on the setup and usage of robotics within their organizations. These managers have described both the ‘centralized’ and ‘decentralized’ approaches to the implementation of robotics. In the centralized system, a single group is charged with all aspects of the robotic project, including justification, purchase, validation, use and maintenance. Under such an
arrangement, samples are usually given to the robotics group for analysis. In contrast, a totally decentralized approach to robotics would have units interspersed throughout the organization, with each individual group responsible for their respective unit(s), in
much the same way as liquid chromatographs are considered.At Hoffmann-La Roche, aspects of both the centralized and decentralized approaches to robotics are used which make our combined system the ‘best of both worlds’. This paper describes the Roche philosophy towards robotics and highlights the advantages to the system used. 相似文献
59.
J. Lau 《European Journal of Lipid Science and Technology》1978,80(9):355-357
Oil Refining: Data on Product, Energy, Process, Environmental Pollution, and Processing Data from Large Technical Plants The need to develope new methods for processing new raw materials, meeting wider market demands, conserving energy and providing environmental protection is discussed. Physical refinement provides the means to accomplish these ends, as well as being the only practical way to overcome certain new problems such as contamination with pesticides. Modern steam distillation equipment is flexible enough to handle a wide range of energy usage, recovering the fatty acids in a directly useable form without use of lye and soapstock splitting, and with very low oil losses. Data is provided to show the extreme economy of one particular method versus other physical refining equipment, and to give information on the product quality. A formula is presented to prove the reality of the low stripping steam usage achieved in practice. 相似文献
60.
A goal of network tomography is to infer the status (e.g. delay) of congested links internal to a network, through end-to-end measurements at boundary nodes (end-hosts) via insertion of probe signals. Because (a) probing constitutes traffic overhead, and (b) in any typical scenario, the number of congested links is a small fraction of the total number in the network, a desirable design objective is to identify those (few) congested links using a minimum number of probes. In this paper, we make a contribution to solving this problem, by proposing a new two-stage approach for this problem. First, we develop a binary observation model linking end-to-end observations with individual link statuses and derive necessary and sufficient conditions for whether at least one link in the network is congested. Stage I of the proposed method shows that achieving 1-identifiability with a minimum number of probes is equivalent to the familiar minimum set covering problem that can be efficiently solved via a greedy heuristic. A sequential algorithm is described, leading to a significantly lowered computational complexity vis-a-vis a batch algorithm. Next, a binary splitting algorithm originally developed in group testing is used to identify the location of the congested links. The proposed scheme is evaluated by simulations in OPNET and experiments on the PlanetLab testbed to validate the advantages of our 2-stage approach vis-a-vis a conventional (batch) algorithm. 相似文献