732 research outputs found

    Seroprevalence of bovine anaplasmosis caused by Anaplasma marginale in Malaysia

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    Anaplasmosis, also known as yellow fever, is an infectious parasitic disease of cattle caused by the protozoan Anaplasma marginale. Anaplasma marginale infects the erythrocytes and causes severe anaemia, weakness, loss of appetite, fever, depression, abortion, decreased milk production, constipation, jaundice and sometimes death. In Malaysia, data on A. marginale infection is still behind compared to other parasites such as nematodes. Anaplasmosis in livestock has received little attention in Malaysia with only occasional reports in cattle. In addition, the determinants of tick- and fly-borne transmission are not well understood. Looking into this possibility, this study was carried out to investigate and to compare the prevalence rate of bovine anaplasmosis in Malaysia. A seroprevalence study on bovine anaplasmosis was conducted at the Veterinary Research Institute, Malaysia. Sera of various cattle breeds were collected from farms and abattoirs to be tested for the presence of A. marginale. Competitive enzyme-linked immunosorbent assay (c-ELISA) Anaplasma antibody test kits by VMRD, Inc. were used for this study, where antibodies to A. marginale from sample sera inhibit the binding of horseradish peroxidase (HRP)-labelled monoclonal antibody to the Anaplasma antigen coated on the plastic wells. A total number of 267 serum samples were tested and 79.4% were positive for bovine anaplasmosis. Results showed that the infection percentage is 100% in Pahang while the state with lowest infection percentage is Sabah with 59.2%. A comparison is done between Peninsular Malaysia with Sabah and Sarawak. The infection percentage in Peninsular Malaysia is higher at 87% while Sabah and Sarawak has an infection percentage of 60%. However, there is no significant difference in the rate of infections. The high number of cases in Peninsular Malaysia may be caused by the lack of strict control measures due to dependence on modern tools and drugs, while cases in Sabah and Sarawak may be due to traditional practices carried out frequently that may cause iatrogenic transmission. More samples should be obtained in order to validate the results. In addition, annual studies must be done to monitor the status of A. marginale prevalence in local cattle that is medically and economically significant to Malaysia

    Shear-strain-induced Spatially Varying Super-lattice Structures on Graphite studied by STM

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    We report on the Scanning Tunneling Microscope (STM) observation of linear fringes together with spatially varying super-lattice structures on (0001) graphite (HOPG) surface. The structure, present in a region of a layer bounded by two straight carbon fibers, varies from a hexagonal lattice of 6nm periodicity to nearly a square lattice of 13nm periodicity. It then changes into a one-dimensional (1-D) fringe-like pattern before relaxing into a pattern-free region. We attribute this surface structure to a shear strain giving rise to a spatially varying rotation of the affected graphite layer relative to the bulk substrate. We propose a simple method to understand these moire patterns by looking at the fixed and rotated lattices in the Fourier transformed k-space. Using this approach we can reproduce the spatially varying 2-D lattice as well as the 1-D fringes by simulation. The 1-D fringes are found to result from a particular spatial dependence of the rotation angle.Comment: 14 pages, 6 figure

    X-ray absorption spectroscopy studies of Ba1-xCaxTiO3

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    [[abstract]]We report x-ray absorption near edge spectroscopy (XANES) of Ca and O K-edges of Ba1-xCaxTiO3 (x = 0, 0.01, 0.08, 1) and understand the spectral features related to the electronic structure of these perovskites. The XANES spectra of Ca K-edge possess a pre-edge peak similar to other 3d transition metals like Ti, Ni when present in perovskite structure and provides information about p-type or hole doping. Presence of considerable amount of 3d states justifies the reason to consider it as a light 3d transition metal. The O K-edge spectra display characteristic spectral features assigned as eg and t2g and show strong dependence on concentration.[[notice]]èŁœæ­ŁćźŒç•ą[[journaltype]]ćœ‹ć€–[[booktype]]çŽ™æœŹ[[booktype]]é›»ć­ç‰ˆ[[countrycodes]]US

    Temperature Induced Degradation of Nb Ti/Cu Composite Superconductors

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    The degradation mechanisms of state-of-the-art Nb-Ti/Cu superconductors are described, based on in-situ synchrotron X-ray diffraction measurements during heat treatment. A quantitative description of the Nb-Ti/Cu degradation in terms of critical current density, Cu stabiliser resistivity and mechanical composite strength is presented. In an applied magnetic field a significant critical current degradation is already observed after a 5-minute 400 °C heat treatment, due to variations of a-Ti precipitate size and distribution within the Nb-Ti alloy filaments. A strong degradation of the strand mechanical properties is observed after several minutes heating above 550 °C, which is also the temperature at which the formation of Cu Ti intermetallic phases is detected. Several minutes heating at 250 °C are sufficient to increase the RRR of the strongly cold work strands inside a Rutherford type cable from about 80 to about 240. Heating for several minutes at 400 °C does not cause a significant conductor degradation in self-field and, thus, leaves enough temperature margin for the electrical interconnection of Nb-Ti/Cu conductors with common low temperature solders

    Phase Transformations during the Reaction Heat Treatment

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    The evolution of Nb containing phases during the diffusion heat treatment of three different high critical current Nb3_{3}Sn strand types is compared, based on synchrotron X-ray diffraction results that have been obtained at the ID15 beam line of the European Synchrotron Radiation Facility (ESRF). In all strands studied, Nb3_{3}Sn formation is preceded by the formation of a Cu-Nb-Sn ternary phase, NbSn2 and Nb6Sn5. As compared to the PIT and Tube Type strand, the amount of these phases formed in the RRP strand is relatively small. In the RRP strand subelements with a fine filament structure Nb3_{3}Sn grows more quickly, thereby preventing to a large extent the formation of the other higher tin phases

    Electronic states of disordered grain boundaries in graphene prepared by chemical vapor deposition

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    Perturbations of the two dimensional carbon lattice of graphene, such as grain boundaries, have significant influence on the charge transport and mechanical properties of this material. Scanning tunneling microscopy measurements presented here show that localized states near the Dirac point dominate the local density of states of grain boundaries in graphene grown by chemical vapor deposition. Such low energy states are not reproduced by theoretical models which treat the grain boundaries as periodic dislocation-cores composed of pentagonal-heptagonal carbon rings. Using ab initio calculations, we have extended this model to include disorder, by introducing vacancies into a grain boundary consisting of periodic dislocation-cores. Within the framework of this model we were able to reproduce the measured density of states features. We present evidence that grain boundaries in graphene grown on copper incorporate a significant amount of disorder in the form of two-coordinated carbon atoms. © 2013 Elsevier Ltd. All rights reserved

    AWPP: A New Scheme for Wireless Access Control Proportional to Traffic Priority and Rate

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    Cutting-edge wireless networking approaches are required to efficiently differentiate traffic and handle it according to its special characteristics. The current Medium Access Control (MAC) scheme which is expected to be sufficiently supported by well-known networking vendors comes from the IEEE 802.11e workgroup. The standardized solution is the Hybrid Coordination Function (HCF), that includes the mandatory Enhanced Distributed Channel Access (EDCA) protocol and the optional Hybrid Control Channel Access (HCCA) protocol. These two protocols greatly differ in nature and they both have significant limitations. The objective of this work is the development of a high-performance MAC scheme for wireless networks, capable of providing predictable Quality of Service (QoS) via an efficient traffic differentiation algorithm in proportion to the traffic priority and generation rate. The proposed Adaptive Weighted and Prioritized Polling (AWPP) protocol is analyzed, and its superior deterministic operation is revealed

    Carbon nanotube substrates enhance SARS-CoV-2 spike protein ion yields in matrix assisted laser desorption-ionization mass spectrometry

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    Nanostructured surfaces enhance ion yields in matrix assisted laser desorption-ionization mass spectrometry (MALDI-MS). The spike protein complex, S1, is one fingerprint signature of Sars-CoV-2 with a mass of 75 kDa. Here, we show that MALDI-MS yields of Sars-CoV-2 spike protein ions in the 100 kDa range are enhanced 50-fold when the matrix-analyte solution is placed on substrates that are coated with a dense forest of multi-walled carbon nanotubes, compared to yields from uncoated substrates. Nanostructured substrates can support the development of mass spectrometry techniques for sensitive pathogen detection and environmental monitoring
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