Search Results (5)

In this study, the hyperbaric (2 bar) laser chemical vapor deposition of TiC fibers grown under various percent pressures of hydrogen and ratios of ethylene and titanium tetrachloride (2:1 or 1:1) are reported. In the hydrogen-rich (85%) condition, sequential fiber depositions became stunted as a result of a loss of hydrogen, which served as a reducing agent for the metal halide as hydrogen evolved with the hydrocarbon gas in the reaction zone because of the Le Chatelier principle. For the hydrogen-lean (25%) condition, the intrinsic fiber growth rate was invariant, but gas phase nucleation resulted in the hydrocarbon forming carbon soot in the chamber which subsequently deposited and coated on the fibers. In the hydrogen-balanced composition (50%), the 2:1 precursor ratio resulted in inconsistent intrinsic growth rates which ranged from approximately 30 μm/s to 44 μm/s. However, for the hydrogen-balanced (50%) 1:1 condition, the intrinsic growth rate variation was reduced to approximately 12 μm/s. The differences in fiber uniformity, composition, and structure under these process conditions are discussed in terms of hydrogen’s ability to serve as a reducing agent, a fluid to transport heat from the deposition zone, and alter the structure of the fiber through thermophoresis. Full article

In this paper, a light-controlled variable damping system (LCVDS) is proposed based on PLZT ceramics and electrorheological fluid (ERF). The mathematical models for the photovoltage of PLZT ceramics and the hydrodynamic model for the ERF are established, and the relationship between the pressure difference at both ends of the microchannel and the light intensity is deduced. Then, simulations are conducted by applying different light intensities in the LCVDS to analyze the pressure difference at both ends of the microchannel using COMSOL Multiphysics. The simulation results show that the pressure difference at both ends of the microchannel increases with the increase in light intensity, which is consistent with results from the mathematical model established in this paper. The error rate of the pressure difference at both ends of the microchannel is within 13.8% between the theoretical and simulation results. This investigation lays the foundation for the application of light-controlled variable damping in future engineering. Full article

Monitoring the transboundary spread of peste des petits ruminants (PPR) virus is an essential part of the global efforts towards the eradication of PPR by 2030. There is growing evidence that Lineage IV is becoming the predominant viral lineage, replacing Lineage I and II in West Africa. As part of a regional investigation, samples collected in Burkina Faso, Côte d’Ivoire, Guinea and Ghana were screened for the presence of PPRV. A segment of the nucleoprotein gene from positive samples was sequenced, and phylogenetic analysis revealed the co-circulation of Lineage II and IV in Burkina Faso, Côte d’Ivoire and Guinea, and the identification of Lineage IV in Ghana. These data will be of importance to local and regional authorities involved in the management of PPRV spread. Full article

Lymphocystic disease affects over 150 species of marine and freshwater fish worldwide. In this study, the lymphocystis pathogen was found in 2 (Amphiprion ocellaris and Amphiprion clarkii) of the 9 species of clownfish. Detection of lymphocystis disease virus (LCDV) was based on histopathological study, electron microscope observation of virus particles and gene sequence analysis from the MCP region. Infected A. ocellaris hosts showed sparse, multifocal, white, stiff, papilloma-like nodules on the body, skin, gills and fins; while, on A. clarkia, nodules were found on the operculum skin. Histopathologic study showed lymphocystic cells with an irregular nucleus, enlarged cytoplasm and intracytoplasmic inclusion bodies surrounded by the cell membrane. The viral particle presents virions 180–230 nm in diameter, hexagonal in shape with an inner dense nucleoid under transmission electron micrographs (TEM). From the ML polygenetic tree, the clownfish LCVD genotype was closely related to the LCDV strain from paradise fish, Macropodus opercularis (KJ408271) (pairwise distance: 92.5%) from China, then followed by the strain from Spain (GU320726 and GU320736) (pairwise distance: 90.8–90.5%), Korea (AB299163, AB212999, AB213004, and AB299164) (pairwise distance: 91.5–80.5%) and lastly Canada (GU939626) (pairwise distance: 83%). This is the first report of lymphocystis disease in A. clarkii in Taiwan. Full article

Carbon-based materials (CBMs) such as graphene, carbon nanotubes (CNT), highly ordered pyrolytic graphite (HOPG), and pyrolytic carbon (PyC) have received a great deal of attention in recent years due to their unique electronic, optical, thermal, and mechanical properties. CBMs have been grown using a variety of processes, including mechanical exfoliation, pulsed laser deposition (PLD), and chemical vapor deposition (CVD). Mechanical exfoliation creates materials that are irregularly formed and tiny in size. On the other hand, the practicality of the PLD approach for large-area high-quality CMB deposition is quite difficult. Thus, CVD is considered as the most effective method for growing CBMs. In this paper, a novel pulsed laser-assisted chemical vapor deposition (LCVD) technique was explored to determine ways to reduce the energy requirements to produce high quality CBMs. Different growth parameters, such as gas flow rate, temperature, laser energy, and deposition time were considered and studied thoroughly to analyze the growth pattern. CBMs are grown on Si and Cu substrates, where we find better quality CBM films on Cu as it aids the surface solubility of carbon. Raman spectroscopy confirms the presence of high-quality PyC which is grown at a temperature of 750 °C, CH₄ gas flow rate of 20 sccm, a laser frequency of 10 Hz, and an energy density of 0.116 J/cm² per pulse. It is found that the local pulsed-laser bombardment helps in breaking the carbon-hydrogen bonds of CH₄ at a much lower substrate temperature than its thermal decomposition temperature. There is no significant change in the 2D peak intensity in the Raman spectrum with the further increase in temperature which is the indicator of the number of the graphene layer. The intertwined graphene flakes of the PyC are observed due to the surface roughness, which is responsible for the quenching in the Raman 2D signal. These results will provide the platform to fabricate a large area single layer of graphene, including the other 2D materials, on different substrates using the LCVD technique. Full article