2,661 research outputs found

    Semiconductor Materials by Ultrasonic Spray Pyrolysis and Their Application in Electronic Devices

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    Ultrasonic spray pyrolysis is a deposition technique that enables a fine mist of the precursor solution in order to deposit higher-density thin films. This characteristic makes of great potential the use of ultrasonically spray-deposited semiconductors films for low-cost, transparent, flexible and large-area applications. In this chapter, low-temperature deposition and characterization of ultrasonically spray-deposited zinc oxide (ZnO) films are presented. The ZnO films deposited by ultrasonic spray pyrolysis at 200°C were characterized by optical transmittance, photoluminescence spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The study of low-temperature annealing of ZnO films is also presented. Moreover, the characterization of aluminum-doped ZnO films deposited by ultrasonic spray pyrolysis at 200°C is presented. Finally, applications of these ultrasonic spray-deposited films in electronic devices are presented

    Integrated approach to assignment, scheduling and routing problems

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    This research considers a real life case study that determines the minimum number of sellers required to attend a set of customers located in a certain region taking into account the weekly schedule plan of the visits, as well as the optimal route. The problem is formulated as a combination of assignment, scheduling and routing problems. In the new formulation, case studies of small size subset of customers of the above type can be solved optimally. However, this subset of customers is not representative within the business plan of the company. To overcome this limitation, the problem is divided into three phases. A greedy algorithm is used in Phase I in order to identify a set of cost-effective feasible clusters of customers assigned to a seller. Phase II and III are then used to solve the problem of a weekly program for visiting the customers as well as to determine the route plan using MILP formulation. Several real life instances of different sizes have been solved demonstrating the efficiency of the proposed approach

    Clostridium perfringens epsilon toxin induces blood brain barrier permeability via caveolae-dependent transcytosis and requires expression of MAL.

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    Clostridium perfringens epsilon toxin (ETX) is responsible for causing the economically devastating disease, enterotoxaemia, in livestock. It is well accepted that ETX causes blood brain barrier (BBB) permeability, however the mechanisms involved in this process are not well understood. Using in vivo and in vitro methods, we determined that ETX causes BBB permeability in mice by increasing caveolae-dependent transcytosis in brain endothelial cells. When mice are intravenously injected with ETX, robust ETX binding is observed in the microvasculature of the central nervous system (CNS) with limited to no binding observed in the vasculature of peripheral organs, indicating that ETX specifically targets CNS endothelial cells. ETX binding to CNS microvasculature is dependent on MAL expression, as ETX binding to CNS microvasculature of MAL-deficient mice was not detected. ETX treatment also induces extravasation of molecular tracers including 376Da fluorescein salt, 60kDA serum albumin, 70kDa dextran, and 155kDA IgG. Importantly, ETX-induced BBB permeability requires expression of both MAL and caveolin-1, as mice deficient in MAL or caveolin-1 did not exhibit ETX-induced BBB permeability. Examination of primary murine brain endothelial cells revealed an increase in caveolae in ETX-treated cells, resulting in dynamin and lipid raft-dependent vacuolation without cell death. ETX-treatment also results in a rapid loss of EEA1 positive early endosomes and accumulation of large, RAB7-positive late endosomes and multivesicular bodies. Based on these results, we hypothesize that ETX binds to MAL on the apical surface of brain endothelial cells, causing recruitment of caveolin-1, triggering caveolae formation and internalization. Internalized caveolae fuse with early endosomes which traffic to late endosomes and multivesicular bodies. We believe that these multivesicular bodies fuse basally, releasing their contents into the brain parenchyma

    Integrated Approach to Assignment, Scheduling and Routing Problems in a Sales Territory Business Plan

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    AbstractThis paper considers a real life case study that determines the minimum number of sellers required to attend a set of customers located in a certain region taking into account the weekly schedule plan of the visits, as well as the optimal route. The problem is formulated as a combination of assignment, scheduling and routing problems. In the new formulation, case studies of small size subset of customers of the above type can be solved optimally. However, this subset of customers is not representative within the business plan of the company. To overcome this limitation, the problem is divided into three phases. A greedy algorithm is used in Phase I in order to identify a set of cost-effective feasible clusters of customers assigned to a seller. Phase II and III are then used to solve the problem of a weekly program for visiting the customers as well as to determine the route plan using MILP formulation. Several real life instances of different sizes have been solved demonstrating the efficiency of the proposed approach

    Fault Diagnosis of Electric Transmission Lines Using Modular Neural Networks

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    "(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works."This paper proposes a new method for fault diagnosis in electric power systems based on neural networks. With this method the diagnosis is performed by assigning a neural module for each type of component of the electric power system, whether it is a transmission line, bus or transformer. The neural modules for buses and transformers comprise two diagnostic levels which take into consideration the logic states of switches and relays, both internal and back-up. The neural module for transmission lines also has a third diagnostic level which takes into account the oscillograms of fault voltages and currents, as well as the frequency spectrums of these oscillograms, in order to verify if the transmission line had in fact been subjected to a fault. One important advantage of the diagnostic system proposed is that its implementation does not require the use of a network configurator for the system; it does not depend on the size of the power network, nor does it require retraining of the neural modules if the power network increases in size, making its application possible to only one component, a specific area, or the whole context of the power system..Flores, A.; Quiles Cucarella, E.; GarcĂ­a Moreno, E.; Morant Anglada, FJ. (2016). Fault Diagnosis of Electric Transmission Lines Using Modular Neural Networks. IEEE Latin America Transactions. 14(8):3663-3668. doi:10.1109/TLA.2016.7786348S3663366814

    Numerical Study of the Seismic Response of an Urban Overpass Support System

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    A strategic urban overpass is to be built in the so-called transition and hill zones in Mexico City. The subsoil conditions at these zones typically consist on soft to stiff clay and medium to dense sand deposits, randomly interbedded by loose sand lenses, and underlain by rock formations that may outcrop in some areas. Several critical supports of this overpass are going to be instrumented with accelerometers, inclinometers and extensometers to assess their seismic performance during future earthquakes and to generate a database to calibrate soil-structure-interaction numerical models. This paper presents the seismic performance evaluation of one of these supports. The support foundation is a 3.6 by 4.6 m mat, structurally connected to four cast-in-place 0.80 m diameter piles. A finite elements model of the soil-foundation-structure system was developed. Initially, the model was calibrated analyzing the seismic response that an instrumented bridge support exhibited during the June 15th, 1999 Tehuacan (Mw=7) Earthquake. This bridge is located also within the surroundings of Mexico City, but at the lake zone, where highly compressible clays are found. The computed response was compared with the measured response in the free field, box foundation, and structure. Once the model prediction capabilities were established, the seismic response of the critical support of the urban overpass was evaluated for the design earthquake in terms of transfer functions and displacement time histories

    Metal-Semiconductor Interfaces in Thin-Film Transistors

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    The metal-semiconductor interface in thin-film transistors (TFTs) is one of the bottlenecks on the development of these devices. Although this interface does not play an active role in the transistor operation, a low-quality interface can be responsible for a low performance operation. In a-Si TFTs, a doped film can be used to improve this interface, however, in other TFT technologies, there is no doped film to be used. In this chapter, some alternatives to improve this interface are analysed. Also, the influence of this interface on the electrical stability of these devices is presented

    Minimally Invasive Laminate Veneer Therapy for Maxillary Central Incisors.

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    Minimally invasive dentistry is a considered process that requires the clinician to be prepared with the ideal sequence and the tools needed. This report describes a well-planned ultraconservative approach using only two ceramic laminate veneers for the maxillary central incisors to significantly improve the patient's overall smile. A 30-year-old female presented with the chief complaints of having diastemas between the central and lateral incisors as well as incisal wear. Diagnostic wax-up and mock-up were performed, and the patient approved the minimally invasive treatment with veneers only for central incisors. A reduction guide aided the conservative tooth preparations, and hand-crafted feldspathic veneers were bonded under total isolation with a rubber dam. The two final conservative veneers significantly improved the smile and fulfilled the patient's expectations. Following proper planning and sequencing, predictable outcomes were obtained and fulfilled the patient's esthetic demands. Minimally invasive restorative dentistry with only two single veneers can impact the entire smile frame. Overtreatment in the esthetic zone is unnecessary to meet a patient's esthetic expectations

    Coccolithophore biodiversity controls carbonate export in the Southern Ocean

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    Southern Ocean waters are projected to undergo profound changes in their physical and chemical properties in the coming decades. Coccolithophore blooms in the Southern Ocean are thought to account for a major fraction of the global marine calcium carbonate (CaCO3) production and export to the deep sea. Therefore, changes in the composition and abundance of Southern Ocean coccolithophore populations are likely to alter the marine carbon cycle, with feedbacks to the rate of global climate change. However, the contribution of coccolithophores to CaCO3 export in the Southern Ocean is uncertain, particularly in the circumpolar subantarctic zone that represents about half of the areal extent of the Southern Ocean and where coccolithophores are most abundant. Here, we present measurements of annual CaCO3 flux and quantitatively partition them amongst coccolithophore species and heterotrophic calcifiers at two sites representative of a large portion of the subantarctic zone. We find that coccolithophores account for a major fraction of the annual CaCO3 export, with the highest contributions in waters with low algal biomass accumulations. Notably, our analysis reveals that although Emiliania huxleyi is an important vector for CaCO3 export to the deep sea, less abundant but larger species account for most of the annual coccolithophore CaCO3 flux. This observation contrasts with the generally accepted notion that high particulate inorganic carbon accumulations during the austral summer in the subantarctic Southern Ocean are mainly caused by E. huxleyi blooms. It appears likely that the climate-induced migration of oceanic fronts will initially result in the poleward expansion of large coccolithophore species increasing CaCO3 production. However, subantarctic coccolithophore populations will eventually diminish as acidification overwhelms those changes. Overall, our analysis emphasizes the need for species-centred studies to improve our ability to project future changes in phytoplankton communities and their influence on marine biogeochemical cycles.info:eu-repo/semantics/publishedVersio
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