The kinetics of desilication of synthetic spent Bayer liquor and sodalite crystal growth

The kinetics of desilication of synthetic, sodium aluminosilicate solution (spent Bayer liquor) and growth of sodalite crystals have been studied under isothermal, batch crystallization conditions close to those prevailing in Bayer process heat exchangers. The desilication rate of the liquor via the formation and growth of sodalite scale on steel substrates was found to be independent of agitation rate. With sodalite seeding, the desilication rate was observed to increase dramatically due to seed crystal growth with the suppression of scale formation. An activation energy of 30 kJ mol−1 and a second order dependence of the desilication rate on relative supersaturation of SiO2 were obtained for sodalite crystal growth

The performing animal: causes and consequences of body remodeling and metabolic adjustments in red knots facing contrasting thermal environments

Using red knots (Calidris canutus) as a model, we determined how changes in mass and metabolic activity of organs relate to temperature-induced variation in metabolic performance. In cold-acclimated birds, we expected large muscles and heart as well as improved oxidative capacity and lipid transport, and we predicted that this would explain variation in maximal thermogenic capacity (Msum). We also expected larger digestive and excretory organs in these same birds and predicted that this would explain most of the variation in basal metabolic rate (BMR). Knots kept at 5°C were 20% heavier and maintained 1.5 times more body fat than individuals kept in thermoneutral conditions (25°C). The birds in the cold also had a BMR up to 32% higher and a Msum 16% higher than birds at 25°C. Organs were larger in the cold, with muscles and heart being 9–20% heavier and digestive and excretory organs being 21–36% larger than at thermoneutrality. Rather than the predicted digestive and excretory organs, the cold-induced increase in BMR correlated with changes in mass of the heart, pectoralis, and carcass. Msum varied positively with the mass of the pectoralis, supracoracoideus, and heart, highlighting the importance of muscles and cardiac function in cold endurance. Cold-acclimated knots also expressed upregulated capacity for lipid transport across mitochondrial membranes [carnitine palmitoyl transferase (CPT)] in their pectoralis and leg muscles, higher lipid catabolism capacity in their pectoralis muscles [β-hydroxyacyl CoA-dehydrogenase (HOAD)], and elevated oxidative capacity in their liver and kidney (citrate synthase). These adjustments may have contributed to BMR through changes in metabolic intensity. Positive relationships among Msum, CPT, and HOAD in the heart also suggest indirect constraints on thermogenic capacity through limited cardiac capacity

Role of microbial diversity for sustainable pyrite oxidation control in acid and metalliferous drainage prevention

Acid and metalliferous drainage (AMD) remains a challenging issue for the mining sector. AMD management strategies have attempted to shift from treatment of acid leachates post-generation to more sustainable at-source prevention. Here, the efficacy of microbial–geochemical at-source control approach was investigated over a period of 84 weeks. Diverse microbial communities were stimulated using organic carbon amendment in a simulated silicate-containing sulfidic mine waste rock environment. Mineral waste in the unamended leach system generated AMD quickly and throughout the study, with known lithotrophic iron- and sulfur-oxidising microbes dominating column communities. The organic-amended mineral waste column showed suppressed metal dissolution and AMD generation. Molecular DNA-based next generation sequencing confirmed a less diverse lithotrophic community in the acid-producing control, with a more diverse microbial community under organic amendment comprising organotrophic iron/sulfur-reducers, autotrophs, hydrogenotrophs and heterotrophs. Time-series multivariate statistical analyses displayed distinct ecological patterns in microbial diversity between AMD- and non-AMD-environments. Focused ion beam-TEM micrographs and elemental mapping showed that silicate-stabilised passivation layers were successfully established across pyrite surfaces in organic-amended treatments, with these layers absent in unamended controls. Organic amendment and resulting increases in microbial abundance and diversity played an important role in sustaining these passivating layers in the long-term. © 2020 Elsevier B.V

Effect of niobium on the structure of titanium dioxide thin films

This paper reports the effect of niobium on the structure of titanium dioxide (TiO2) thin films deposited on glass. The results obtained indicated that the direct current (DC) co-sputtering of Ti and Nb onto glass substrates in the presence of oxygen results in the formation of Nb-doped anatase thin films with strong preferential orientation. In the concentration range between 0 and 40 at.% Nb, niobium is incorporated into the TiO2 lattice according to a substitution mechanism, entering Ti sites in the cation sub-lattice. No evidence exists for a solubility limit < 40 at.% of Nb under the applied deposition conditions, however, it is not believed that an equilibrium situation prevails. Lattice charge compensation was concluded to occur by the formation of cation vacancies for samples with up to 10 at.% Nb, and by Ti3+ or Nb4+ ions for the samples with ≥ 15 at.% Nb, the latter in conjunction with cation vacancy compensation

The functional significance of facultative hyperthermia varies with body size and phylogeny in birds

1. Facultative hyperthermia, the elevation of body temperature above normothermic levels, during heat exposure, importantly affects the water economy and heat balance of terrestrial endotherms. We currently lack a mechanistic understanding of the benefits hyperthermia provides for avian taxa. 2. Facultative hyperthermia has been proposed to minimize rates of water loss via three distinct mechanisms: M1) by maintaining body temperature (Tb) above environmental temperatures (Te), heat can be lost non‐evaporatively, saving water; M2) by minimizing the thermal gradient when Te > Tb, environmental heat gain and evaporative water loss rates are reduced; and M3) by storing heat via increases in Tb which reduces evaporative heat loss demands and conserves water. 3. Although individuals may benefit from all three mechanisms during heat exposure, the relative importance of each mechanism has not been quantified among species that differ in their body size, heat tolerance and mechanisms of evaporative heat dissipation. 4. We measured resting metabolism, evaporative water loss and real‐time Tb from 33 species of birds representing nine orders ranging in mass from 8 to 300 g and estimated the water savings associated with each proposed mechanism. We show that facultative hyperthermia varies in its benefits among species. 5. Small songbirds with comparatively low evaporative cooling capacities benefit most from (M1), and hyperthermia maintains a thermal gradient that allows non‐evaporative heat losses. Other species benefited most from (M2) minimizing evaporative losses via a reduced thermal gradient for heat gain at high Te. We found that (M3), heat storage, only improved the water economy of the sandgrouse, providing little benefit to other species. 6. We propose that differences in the frequency and magnitude of hyperthermia will drive taxon‐specific differences in temperature sensitivity of tissues and enzymes and that the evolution of thermoregulatory mechanisms of evaporative heat dissipation may contribute to differences in basal metabolic rate among avian orders. 7. Understanding the mechanistic basis of heat tolerance is essential to advance our understanding of the ecology of birds living in hot environments that are warming rapidly, where extreme heat events are already re‐structuring avian communities.Alexander R. Gerson, Andrew E. McKechnie, Ben Smit, Maxine C. Whitfield Eric K. Smith, William A. Talbot, Todd J. McWhorter, Blair O. Wol

High resolution powder diffraction using synchrotron radiation Application to the structural investigation of n-alkanes and their homologous mixtures

SIGLEAvailable from British Library Document Supply Centre- DSC:6609.025(DL/SCI/P--678E) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Novel kinetic studies of wax crystallisation

SIGLEAvailable from British Library Document Supply Centre- DSC:6609.025(DL/SCI/P--639E) / BLDSC - British Library Document Supply CentreGBUnited Kingdo