Influence of calcination temperatures on lithium deportment by screening hard rock lithium.

Calcination of spodumene is a pre-treatment stage in preparation for sulfation roasting and leaching in lithium recovery. During calcination, α-spodumene (less reactive, monoclinic crystal structure) is converted to ß-spodumene (more reactive, tetragonal crystal structure). A third, metastable γ-phase has been identified at lower temperatures than full conversion to the ß-phase. It has been previously observed that calcination greatly alters the physical properties of the various minerals in pegmatite ores, impacting comminution energy and liberation. Thus, this work investigates the relationships between calcination temperatures and the physical behaviour of hard rock lithium ores. The results showed that the increase in calcination temperature resulted in a higher lithium deportment in the finest size fraction (-0.6 mm) and thus a higher lithium grade and recovery. The samples calcined at 813.15 K and 1223.15 K did not show a significant increase in lithium grades in the finest size fraction. This work shows the incremental change in the physical properties of various minerals in the ore with increasing calcination temperature.

Lithium deportment by size of a calcined spodumene ore.

Calcination of spodumene is used to convert α-spodumene to more reactive ß-spodumene, has been shown to greatly impact the physical characteristics of some of the components in the ore. This work investigates the energy efficiency of different grinding circuits used for upgrading the lithium content in the finer fraction of the calcined spodumene ore. The results showed that closed-circuit grinding resulted in 89% lithium recovery of the finest size fractions (- 0.6 mm) while open-circuit grinding led to 65% lithium recovery for the same grinding time. Closed-circuit grinding consumed lower energy than open-circuit grinding. The grade of the finest size fraction in the case of the open-circuit grinding was 1.7 times more than that in the case of the closed-circuit grinding. This work shows the potential of using different grinding modes to maximize energy efficiency and lithium deportment by size. However, it is suggested that open circuit grinding should be used for beneficiations of spodumene ores.

Effect of calcination on coarse gangue rejection of hard rock lithium ores.

Processing of spodumene ores requires calcination as a compulsory pre-treatment to convert α-spodumene to a more reactive ß-spodumene phase. This transformation takes place at an elevated temperature of above 900 °C and results in a 30% volumetric expansion of the mineral and the product having highly altered physical properties. This work examines these induced properties and the effect of calcination on lithium grade deportment with particle size. XRD analysis showed a significant amount of ß-spodumene in the calcined finest fraction (i.e. the particles less than 0.6 mm). A marked reduction in the bond ball mill work index of the calcined lithium samples (i.e. 42.3%) was recorded supporting the observed fracturing and friable appearance of the sample following α to ß-spodumene conversion. The deportment of lithium to finer fractions was significantly increased when the sample was calcined, indicating selective breakage of the spodumene over gangue minerals.

Meal patterns associated with energy intake in people with obesity.

It is widely assumed that people with obesity have several common eating patterns, including breakfast skipping, eating during the night and high fast-food consumption. However, differences in individual meal and dietary patterns may be crucial to optimising obesity treatment. Therefore, we investigated the inter-individual variation in eating patterns, hypothesising that individuals with obesity show different dietary and meal patterns, and that these associate with self-reported energy intake (rEI) and/or anthropometric measures. Cross-sectional data from 192 participants (aged 20-55 years) with obesity, including 6 d of weighed food records, were analysed. Meal patterns and dietary patterns were derived using exploratory hierarchical cluster analysis and k-means cluster analysis, respectively. Five clear meal patterns were found based on the time-of-day with the highest mean rEI. The daily rEI was highest among 'midnight-eaters' (10 669 (sd 2301) kJ), and significantly (P < 0·05) higher than 'dinner-eaters' (8619 (sd 2301) kJ), 'lunch-eaters' (8703 (sd 2176) kJ) and 'supper-eaters' (8786 (sd 1925) kJ), but not 'regular-eaters' (9749 (sd 2720) kJ). Despite differences of up to 2050 kJ between meal patterns, there were no significant differences in anthropometric measures or physical activity level (PAL). Four dietary patterns were also found with significant differences in intake of specific food groups, but without significant differences in anthropometry, PAL or rEI. Our data highlight meal timing as a determinant of individual energy intake in people with obesity. The study supports the importance of considering a person's specific meal pattern, with possible implications for more person-focused guidelines and targeted advice.

Zibotentan, an Endothelin A Receptor Antagonist, Prevents Amyloid-ß-Induced Hypertension and Maintains Cerebral Perfusion.

Cerebral blood flow is reduced in Alzheimer's disease (AD), which is associated with mid-life hypertension. In people with increased cerebral vascular resistance due to vertebral artery or posterior communicating artery hypoplasia, there is evidence that hypertension develops as a protective mechanism to maintain cerebral perfusion. In AD, amyloid-ß (Aß) accumulation may similarly raise cerebral vascular resistance by upregulation of the cerebral endothelin system. The level of endothelin-1 in brain tissue correlates positively with Aß load and negatively with markers of cerebral hypoperfusion such as increased vascular endothelial growth factor. We previously showed that cerebroventricular infusion of Aß40 exacerbated pre-existing hypertension in Dahl rats. We have investigated the effects of 28-day cerebral infusion of Aß40 on blood pressure and heart rate and their variability; carotid flow; endothelin-1; and markers of cerebral oxygenation, in the (normotensive) Wistar rat, and the modulatory influence of the endothelin A receptor antagonist Zibotentan (ZD4054). Cerebral infusion of Aß caused progressive rise in blood pressure (p < 0.0001) (paired t-test: increase of 3 (0.1-5.6) mmHg (p = 0.040)), with evidence of reduced baroreflex responsiveness, and accumulation of Aß and elevated endothelin-1 in the vicinity of the infusion. Oral Zibotentan (3 mg/kg/d, administered for 31 d) abrogated the effects of Aß40 infusion on baroreflex responsiveness and blood pressure, which declined, although without reduction in carotid blood flow, and Zibotentan caused uncoupling of the positive linear relationship between endothelin-1 and vascular endothelial growth factor, which as a sensor of tissue oxygenation would be expected to increase if there were hypoperfusion.

The homeobox factor Irx3 maintains adipogenic identity.

BACKGROUND: Inhibition of Irx3 and Irx5 has been shown to reduce body weight and white adipose tissue (WAT) mass through cell-autonomous and sympathetic-induced increases in adipocyte beiging and thermogenesis in mice and humans. However, the underlying mechanisms of the Irx control over beiging are still largely unknown, as illustrated by recent reports showing divergent effects of Irx3 on adipocyte metabolism and function. Here, we investigated the role of Irx3 in controlling beige preadipocyte function and differentiation. METHODS: Stable knock out of Irx3 in ME3 mouse preadipocytes capable of beiging was performed using a CRISPR-Cas9 system, and the effect on cell differentiation was assessed by qPCR, RNA-seq, Oil-red-O lipid staining and Alcian Blue staining of proteoglycans. Changes in cell identities were validated using cell type enrichment analysis from RNA-seq data. Proliferation and cell cycle progression in undifferentiated cells were measured by WST-1 and flow cytometry, reactive oxygen species (ROS) generation was determined by fluorescence spectrometry and mitochondrial respiration was investigated by Seahorse assay. RESULTS: Irx3 was found to be essential for the identity, function and adipogenic differentiation of beige adipocyte precursors. Irx3-KO impaired proliferation, ROS generation and mitochondrial respiration in the preadipocytes. We further observed profound changes in numerous genes during both early and late stages of adipogenic differentiation, including genes important for adipocyte differentiation, cell cycle progression, oxidative phosphorylation (OXPHOS) and morphogenesis. Irx3-KO cells failed to accumulate lipids following adipogenic stimuli, and cell enrichment analysis revealed a loss of preadipocyte identity and a gain of chondrocyte-like identity in Irx3-KO cells during early differentiation. Finally, unlike the control cells, the Irx3-KO cells readily responded to chondrogenic stimuli. CONCLUSIONS: Irx3 is required for preadipocyte identity and differentiation capacity. Our findings suggest that, while inhibition of Irx3 may be beneficial during later developmental stages to modulate adipogenesis in the beige direction, constitutive and complete absence of Irx3 in the embryonic fibroblast stage leads to detrimental loss of adipogenic differentiation capacity.

Synthesis and characterisation of ferrihydrite/silica co-precipitates.

The effect of the presence of soluble silicates on ferrihydrite precipitation and some properties of the products formed in co-precipitation of ferrihydrite and silica have been investigated. The co-precipitates were formed using a continuous crystallisation process in which a combined iron/silicon feed solution was reacted with sodium hydroxide at a constant rate, while maintaining pH at 2.65 and temperature at 85 degrees C. The products of co-precipitation and the supernatant solutions were characterised using a variety of analytical techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM) and surface charge measurements. The addition of silicates was shown to have a significant impact on the crystallinity and surface charge of the precipitates formed. For products collected after five residence times in the continuous crystalliser, co-precipitates formed from ferric sulfate solution were found to contain considerably less silica than those formed from ferric nitrate. We conclude that adsorption of silicate species on ferrihydrite surfaces speeds up the polymerisation process, and that sulfate ion competes with silicate for surface adsorption sites. Thus, the precipitation of silica proceeds much more rapidly in ferric nitrate media, than in ferric sulfate.