Design study of a horizontal axis tidal turbine blade

Purpose: A design study was conducted to understand the implications of bio-mimicking a curved caudal fin type horizontal axis tidal turbine blade design, using NACA 0018 is presented. Design/methodology/approach: A method of transforming the traditional horizontal axis tidal turbine by defining a third order polynomial centre line on which the symmetrical airfoils were stationed is also disclosed. Each of the airfoil characteristics: twist angle distribution, chord lengths, and centre line passing through the airfoil centres were automatically transformed to create the curved caudal fin-shaped blade; translating the spinal blade axis into percentage wise chord lengths, using NACA 0018 airfoil. A 3D mesh independency study of a straight blade horizontal axis tidal turbine modelled using Computational Fluid Dynamics (CFD) was carried out. The grid convergence study was produced by employing two turbulence models, the standard k-ε model and Shear Stress Transport (SST) in ANSYS CFX. Findings: Three parameters were investigated: mesh resolution, turbulence model, and power coefficient in the initial CFD, analysis. It was found that the mesh resolution and the turbulence model affect the power coefficient results. The power coefficients obtained from the standard k-ε model are 15% to 20% lower than the accuracy of the SST model. Further analysis was performed on both the designed blades using ANSYS CFX and SST turbulence model. The results between the straight blade designed according to literature and the caudal fin blade showed a maximum power coefficient of 0.4028%, and 0.5073% respectively for 2.5m/s inlet velocity. Originality/ value: An original caudal fin based tidal turbine blade geometry characterised with symmetrical airfoil distribution, which produces higher efficiency throughout the year i.e. even for the lower tidal flow velocities which occur during the winter months, is presented

Hsp70 in mitochondrial biogenesis

The family of hsp70 (70 kilodalton heat shock protein) molecular chaperones plays an essential and diverse role in cellular physiology, Hsp70 proteins appear to elicit their effects by interacting with polypeptides that present domains which exhibit non-native conformations at distinct stages during their life in the cell. In this paper we review work pertaining to the functions of hsp70 proteins in chaperoning mitochondrial protein biogenesis. Hsp70 proteins function in protein synthesis, protein translocation across mitochondrial membranes, protein folding and finally the delivery of misfolded proteins to proteolytic enzymes in the mitochondrial matrix

Copolymerisation as a way to enhance the electrochromic properties of an alkylthiophene oligomer and a pyrrole derivative: copolymer of 3,3'" dihexyl-2,2':5',2":5",2'"-quaterthiophene with (R)-(-)-3-(1-pyrrolyl)propyl-N-(3,5-dinitrobenzoyl)-α-phenylglycinate

The copolymerisation of 3,3'" Dihexyl-2,2':5',2":5",2'"-quaterthiophene (DHQT) and (R)-(-)-3-(1-pyrrolyl)propyl-N-(3,5-dinitrobenzoyl)-α-phenylglycinate (DNBP) was successfully performed electrochemically in acetonitrile (CH3CN) containing tetrabutylammonium tetrafluoroborate ((C4H9)4NBF4) by direct oxidation of monomer mixtures in different feed ratios. Copolymerisation improved the properties of the films of both polymers PDHQT and PDNBP, in respect to the adhesion of PDHQT onto ITO/glass surface and the chromatic contrast of these electrochromic materials. PDHQT, PDNBP and P(DHQT-co-DNBP) films were characterised by FTIR spectroscopy, fluorescence spectroscopy, Scanning Electron Microscopy (SEM) and spectroelectrochemical techniques. Solutions of PDHQT and its copolymers with DNBP (independently of the feed ratio) in N-methylpyrrolidone are fluorescent with emission bands at 555 and 585 nm when excited at 375 nm. Reversible changes in the hue and saturation occur in all the copolymer films from yellow or orange in the reduced state to green or blue in the oxidised state, but were dependent on the proportion of the comonomers used to prepare the copolymers. These changes are more significant for P(DHQT-co-DNBP) films deposited onto ITO/glass with 1:5 feed ratio, as shown by the track of the CIE 1931 xy chromaticity coordinates and by the electrochromic parameters in which this film (thickness 0.8±0.2 μm) presented chromatic contrast (Δ%T) at 660 nm of 62%, coloration efficiency (η) of 266 cm2 C-1 and stability to redox cycling (Δ%T=17% at the 1000th cycle). Therefore, these copolymers are potentially applicable in displays and optoelectronic devices as electrochromic and fluorescent materials

Bose-Einstein Condensates in Optical Lattices: Band-Gap Structure and Solitons

We analyze the existence and stability of spatially extended (Bloch-type) and localized states of a Bose-Einstein condensate loaded into an optical lattice. In the framework of the Gross-Pitaevskii equation with a periodic potential, we study the band-gap structure of the matter-wave spectrum in both the linear and nonlinear regimes. We demonstrate the existence of families of spatially localized matter-wave gap solitons, and analyze their stability in different band gaps, for both repulsive and attractive atomic interactions

Particle Dark Matter Constraints from the Draco Dwarf Galaxy

It is widely thought that neutralinos, the lightest supersymmetric particles, could comprise most of the dark matter. If so, then dark halos will emit radio and gamma ray signals initiated by neutralino annihilation. A particularly promising place to look for these indicators is at the center of the local group dwarf spheroidal galaxy Draco, and recent measurements of the motion of its stars have revealed it to be an even better target for dark matter detection than previously thought. We compute limits on WIMP properties for various models of Draco's dark matter halo. We find that if the halo is nearly isothermal, as the new measurements indicate, then current gamma ray flux limits prohibit much of the neutralino parameter space. If Draco has a moderate magnetic field, then current radio limits can rule out more of it. These results are appreciably stronger than other current constraints, and so acquiring more detailed data on Draco's density profile becomes one of the most promising avenues for identifying dark matter.Comment: 13 pages, 6 figure

Multiple recombination events between two cytochrome P450 loci contribute to global pyrethroid resistance in Helicoverpa armigera

The cotton bollworm, Helicoverpa armigera (Hübner) is one of the most serious insect pest species to evolve resistance against many insecticides from different chemical classes. This species has evolved resistance to the pyrethroid insecticides across its native range and is becoming a truly global pest after establishing in South America and having been recently recorded in North America. A chimeric cytochrome P450 gene, CYP337B3, has been identified as a resistance mechanism for resistance to fenvalerate and cypermethrin. Here we show that this resistance mechanism is common around the world with at least eight different alleles. It is present in South America and has probably introgressed into its closely related native sibling species, Helicoverpa zea. The different alleles of CYP337B3 are likely to have arisen independently in different geographic locations from selection on existing diversity. The alleles found in Brazil are those most commonly found in Asia, suggesting a potential origin for the incursion of H. armigera into the Americas

Decreased occurrence of ketoacidosis and preservation of beta cell function in relatives screened and monitored for type 1 diabetes in Australia and New Zealand

Published December 2022Aims: Islet autoantibody screening of infants and young children in the Northern Hemisphere, together with semi-annual metabolic monitoring, is associated with a lower risk of ketoacidosis (DKA) and improved glucose control after diagnosis of clinical (stage 3) type 1 diabetes (T1D). We aimed to determine if similar benefits applied to older Australians and New Zealanders monitored less rigorously. Methods: DKA occurrence and metabolic control were compared between T1D relatives screened and monitored for T1D and unscreened individuals diagnosed in the general population, ascertained from the Australasian Diabetes Data Network. Results: Between 2005 and 2019, 17,105 relatives (mean (SD) age 15.7 (10.8) years; 52% female) were screened for autoantibodies against insulin, glutamic acid decarboxylase, and insulinoma-associated protein 2. Of these, 652 screened positive to a single and 306 to multiple autoantibody specificities, of whom 201 and 215, respectively, underwent metabolic monitoring. Of 178 relatives diagnosed with stage 3 T1D, 9 (5%) had DKA, 7 of whom had not undertaken metabolic monitoring. The frequency of DKA in the general population was 31%. After correction for age, sex and T1D family history, the frequency of DKA in screened relatives was >80% lower than in the general population. HbA1c and insulin requirements following diagnosis were also lower in screened relatives, consistent with greater beta cell reserve. Conclusions: T1D autoantibody screening and metabolic monitoring of older children and young adults in Australia and New Zealand, by enabling pre-clinical diagnosis when beta cell reserve is greater, confers protection from DKA. These clinical benefits support ongoing efforts to increase screening activity in the region and should facilitate the application of emerging immunotherapies.John M. Wentworth, Helena Oakey, Maria E. Craig, Jennifer J. Couper, Fergus J. Cameron, Elizabeth A. Davis, Antony R. Lafferty, Mark Harris, Benjamin J. Wheeler, Craig Jefferies, Peter G. Colman, Leonard C. Harriso

Isotope tracing of submarine groundwater discharge offshore Ubatuba, Brazil : results of the IAEA–UNESCO SGD project

Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Environmental Radioactivity 99 (2008): 1596-1610, doi:10.1016/j.jenvrad.2008.06.010.Results of groundwater and seawater analyses for radioactive (3H, 222Rn, 223Ra, 224Ra, 226Ra, 228Ra) and stable (2H, 18O) isotopes are presented together with in situ spatial mapping and time-series 222Rn measurements in seawater, direct seepage measurements using manual and automated seepage meters, pore water investigations using different tracers and piezometric techniques, and geoelectric surveys probing the coast. This study represents first time that such a new complex arsenal of radioactive and non-radioactive tracer techniques and geophysical methods have been used for simultaneous submarine groundwater discharge (SGD) investigations. Large fluctuations of SGD fluxes were observed at sites situated only a few meters apart (from 0 cm d-1 to 360 cm d-1; the unit represents cm3/cm2/day), as well as during a few hours (from 0 cm d-1 to 110 cm d-1), strongly depending on the tidal fluctuations. The average SGD flux estimated from continuous 222Rn measurements is 17±10 cm d-1. Integrated coastal SGD flux estimated for the Ubatuba coast using radium isotopes is about 7x103 m3 d-1 per km of the coast. The isotopic composition (δ2H and δ18O) of submarine waters was characterised by significant variability and heavy isotope enrichment, indicating that the contribution of groundwater in submarine waters varied from a small percentage to 20%. However, this contribution with increasing offshore distance became negligible. Automated seepage meters and time-series measurements of 222Rn activity concentration showed a negative correlation between the SGD rates and tidal stage. This is likely caused by sea level changes as tidal effects induce variations of hydraulic gradients. The geoelectric probing and piezometric measurements contributed to better understanding of the spatial distribution of different water masses present along the coast. The radium isotope data showed scattered distributions with offshore distance, which imply that seawater in a complex coast with many small bays and islands was influenced by local currents and groundwater/seawater mixing. This has also been confirmed by a relatively short residence time of 1-2 weeks for water within 25 km offshore, as obtained by short-lived radium isotopes. The irregular distribution of SGD seen at Ubatuba is a characteristic of fractured rock aquifers, fed by coastal groundwater and recirculated seawater with small admixtures of groundwater, which is of potential environmental concern and has implications on the management of freshwater resources in the region.This research was supported by IAEA and UNESCO (IOC and IHP) in the framework of the joint SGD project. Science support for some U.S. investigators was provided by grants from the National Science Foundation (OCE03-50514 to WCB and OCE02-33657 to WSM)