Ocean acidification has the capacity to impact future coccolithophore growth, photosynthesis, and calcification, but experimental culture work with coccolithophores has produced seemingly ...contradictory results and has focused on open-ocean species. We investigated the influence of pCO₂ (between 250 and 750 μatm) on the growth, photosynthetic, and calcification rates of the estuarine coccolithophore Pleurochrysis carterae using a CO₂ manipulation system that allowed for natural carbonate chemistry variability, representing the highly variable carbonate chemistry of coastal and estuarine waters. We further considered the influence of pCO₂ on dark calcification. Increased pCO₂ conditions had no significant impact on P. carterae growth rate or photosynthetic rate. However, P. carterae calcification rates significantly increased at elevated mean pCO₂ concentrations of 750 μatm. P. carterae calcification was somewhat, but not completely, light-dependent, with increased calcification rates at elevated mean pCO₂ conditions in both light and dark incubations. This trend of increased calcification at higher pCO₂ conditions fits into a recently developed substrate-inhibitor concept, which demonstrates a calcification optima concept that broadly fits the experimental results of many studies on the impact of increased pCO₂ on coccolithophore calcification.
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► Correlation of solvent activity on composition for ternary electrolyte solutions. ► The proposed equation is consistent with the thermodynamic limiting behaviour. ► The equation was ...successfully applied to 23 aqueous systems.
An analytical equation is proposed for the dependence on composition of the solvent activity of aqueous ternary electrolyte solutions. This equation was derived taking into account the limiting behaviour that must obey the solvent activity in order to be thermodynamically consistent. The correlation of experimental data corresponding to 23 ternary systems was successfully carried out. The results obtained demonstrate an excellent fitting capability of the proposed equation.
Mycotoxins are natural contaminants of cereals and other food commodities throughout the world and they significantly impact human and animal health. Mycotoxins are toxic secondary metabolites ...produced by species of filamentous fungi growing on grains before harvest and in storage. When ingested, inhaled, or absorbed through skin, mycotoxins may reduce appetite and general performance, and cause sickness or death in humans. Mycotoxins subject to government regulation in most countries include aflatoxins, fumonisins, ochratoxins, deoxynivalenol, zearalenone, and patulin, produced by species of Aspergillus, Fusarium, and Penicillium. Aflatoxins, fumonisins, and ochratoxins pose the most serious threats to human health worldwide. This review describes the prevalence of mycotoxins in foods and its implications on human health, which may help in establishing and carrying out proper management strategies. Data from detailed investigations of food mycotoxins worldwide help provide safer food for consumption and help prioritize future research programs.
Population genetic structure of North Atlantic killer whale samples was resolved from differences in allele frequencies of 17 microsatellite loci, mtDNA control region haplotype frequencies and for a ...subset of samples, using complete mitogenome sequences. Three significantly differentiated populations were identified. Differentiation based on microsatellite allele frequencies was greater between the two allopatric populations than between the two pairs of partially sympatric populations. Spatial clustering of individuals within each of these populations overlaps with the distribution of particular prey resources: herring, mackerel and tuna, which each population has been seen predating. Phylogenetic analyses using complete mitogenomes suggested two populations could have resulted from single founding events and subsequent matrilineal expansion. The third population, which was sampled at lower latitudes and lower density, consisted of maternal lineages from three highly divergent clades. Pairwise population differentiation was greater for estimates based on mtDNA control region haplotype frequencies than for estimates based on microsatellite allele frequencies, and there were no mitogenome haplotypes shared among populations. This suggests low or no female migration and that gene flow was primarily male mediated when populations spatially and temporally overlap. These results demonstrate that genetic differentiation can arise through resource specialization in the absence of physical barriers to gene flow.
The vapour pressure over water (1) sodium chloride (2) and sorbitol (3) ternary solutions of different concentrations (mi ≤ 4, i: 2,3) was measured at 338 K and 348 K. Starting from these data, the ...values of the experimental water activity (a1) were calculated. These data and those obtained for other authors at 293 K, 298 K and 308 K were correlated with a previously developed equation for a1(m2, m3). Thus, the equation parameters and their corresponding temperature dependences were obtained. The corresponding root mean square deviation was evaluated, being in all cases less than 0.005.
•Measurement of the vapour pressure of aqueous NaCl-sorbitol solutions.•Correlation of water activity on a wide range of compositions and temperature.•Dependence on temperature of the parameters in the range (293 ≤ T/K ≤ 348).
A 2.7-km canalised section of the Kallang River, a major storm-water drain and reservoir spillway in Singapore, was rehabilitated into a 3-km naturalised, meandering river between 2009 and 2011. A ...combination of plants, natural materials, and civil engineering techniques were introduced to soften the edges of the waterway, to give it a more natural appearance and prevent soil erosion. Baseline data and published evidence of enhancement of aquatic biodiversity in this naturalised urban waterway are lacking, as there have not been any comprehensive biological surveys of the system to date. To determine the effect of rehabilitation, we quantitatively compared the fish assemblage and abiotic variables in the Kallang River after its rehabilitation (re-named Kallang River at Bishan-Ang Mo Kio Park or KRBAP; 2016–2018) against a downstream unrehabilitated section of the river (Kallang Canal; 2012). Secondly, we qualitatively compared fish assemblages and abiotic variables at the KRBAP and the Kallang Canal, to their source (upstream) reservoir, as well as to natural forest streams in close proximity. The KRBAP has a unique fish assemblage, which is dominated by two non-native cichlid taxa (quetzal cichlid, Vieja melanura (68%) and tilapia, Oreochromis spp. (17%)). Fish species richness (p < 0.001) and the percentage of native species (p = 0.015) was significantly higher in the KRBAP compared to the unrehabilitated canal. Moreover, the abiotic variables at the two sites are also significantly different. The fish assemblage and abiotic variables at the KRBAP resemble those of its (upstream) source reservoir, but contrasts with those of nearby natural forest streams. The unique fish assemblage in the KRBAP is shown to be stable, with similar species captured in high abundances across the three sampling years post-rehabilitation. Given the stability within the rehabilitated stream, further research and monitoring are needed to determine the established food web and predict the possible influence of future non-native species additions.
•Rehabilitation of a concretised canal created a novel fish assemblage.•Fish species richness and % native species are higher in rehabilitated river sections.•The rehabilitated waterway remained dominated by non-native fish species.•Fish assemblage and abiotic variables resemble source reservoir not forest streams.
The hydrogen electrode reaction was studied on iridium electrodes covered by a hydrous oxide film in acid solution. The IrOx·nH2O film was prepared by the application of repetitive cyclic voltammetry ...and it was characterized by the charge of the broad voltammetric peak at 0.97V. It was observed for charges lower than 720μCcm−2 a slight increase of both, the HUPD electroadsorption and the steady state limiting current of hydrogen oxidation, with respect to Ir metal. For higher oxide charge values, both variables decrease while a small anodic peak appears at 0.65V. This behaviour was explained on the basis of the formation of two types of Ir oxide depending on the film thickness and the water concentration profile, which changes the site where the hydrogen reaction takes place.
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•Influence of oxide layers on the hydrogen electrode reaction on iridium•At low thickness, hydrous oxide layer increases the electroactive surface area.•At high thickness, an inner anhydrous oxide layer is formed.•The inner oxide layer decreases the electrocatalytic activity.
Abstract To address the demands in healthcare and industrial settings for spatially resolved magnetic imaging, we present a modular optically pumped magnetometer (OPM) system comprising a ...multi-sensor array of highly sensitive quantum magnetometers. This system is designed and built to facilitate fast prototyping and testing of new measurement schemes by enabling quick reconfiguration of the self-contained laser and sensor modules as well as allowing for the construction of various array layouts with a shared light source. The modularity of this system facilitates the development of methods for managing high-density arrays for magnetic imaging. The magnetometer sensitivity and bandwidth are first characterised in both individual channel and differential gradiometer configurations before testing in a real-world magnetoencephalography environment by measuring alpha rhythms from the brain of a human participant. We demonstrate the OPM system in a first-order axial gradiometer configuration with a magnetic field gradient sensitivity of 10 fT / cm / Hz at a baseline of 4.5 cm. Single-channel operation achieved a sensitivity of 65 fT / Hz . Bandwidths exceeding 200 Hz were achieved for two independent modules. The system’s increased temporal resolution allows for the measurement of spinal cord signals, which we demonstrate by using phantom signal trials and comparing with an existing commercial sensor.
On January 16, 2016, Professor Kym Thorne passed away in his sleep. Kym had a remarkable career and was beloved by his colleagues and friends on many continents. He was an exceptional academic and a ...much-loved and respected colleague and friend to the PAT-NET community as well. Through his legacy of publications, he will continue to encourage inspired thinking and to challenge commonly held beliefs. He is deeply and sincerely missed by those who were fortunate enough to know him.
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BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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