Litium-ontginning uit Zimbabwiese petaliet met behulp van ammoniumbifluoried

Extraction of Li2CO3 from Zimbabwean petalite, from the Bikita deposit, was studied using ammonium bifluoride (ABF) digestion at temperatures ranging from room temperature to 600 oC, and gram quantities of ore. ABF digestion bypasses the conventional hightemperature conversion of the mineral to β-spodumene before acid roasting. The process reaction takes place at surprisingly low temperatures – even at room temperature with slurry formation due to the release of water. Below the melting point of ABF, the main products are LiF, AlF3, K2NaAlF6, and (NH4)2SiF6. (NH4)2SiF6 decomposes readily to form ammonia and gaseous SiF4. At higher temperature, the products are cryolithionite (Li3Na3Al2F12) and eucryptite (LiAlSiO4). The fluoride solids are not readily soluble in water and may be roasted in sulfuric acid at relatively mild conditions for a few tens of minutes, then water leached, with 99 % pure lithium carbonate easily recovered from the aqueous phase.The Fluorochemical Expansion Initiative (FEI).http://www.satnt.ac.zaam2022Chemical Engineerin

Selective sublimation/desublimation separation of ZrF4 and HfF4

The separation of zirconium and hafnium, which is essential in the nuclear industry, is difficult due to the great similarities in their chemical and physical properties. In contrast to the traditional aqueous chloride separation systems, the current process focuses on dry fluoride-based technologies, which produce much lower volumes of chemical waste. In the present work, separation is achieved in both a sublimation and a desublimation step, where the Zr/Hf mole ratio varies between 160 and 245 across the length of desublimer and 86 to 40 within the sublimer. Model predictions for the sublimation/desublimation rates fit the experimental results well, with deviations becoming more apparent as sublimation proceeds. This may be attributed to crust formation preventing the system from reaching thermodynamic equilibrium. The model adequately predicts time- and temperature-dependent mole ratios of both the sublimer residue and of the desublimed mass.This paper was first presented at the AMI Precious Metals 2017 Conference ‘The Precious Metals Development Network’ 17–20 October 2017, Protea Hotel Ranch Resort, Polokwane, South Africa.The AMI of the DST and Necsa.http://www.saimm.co.za/journal-papersam2018Chemical Engineerin

Frequency and phenotypic spectrum of KMT2B dystonia in childhood: A single‐center cohort study

Background: Childhood-onset dystonia is often genetically determined. Recently, KMT2B variants have been recognized as an important cause of childhood-onset dystonia. Objective: To define the frequency of KMT2B mutations in a cohort of dystonic patients aged less than 18 years at onset, the associated clinical and radiological phenotype, and the natural history of disease. Methods: Whole-exome sequencing or customized gene panels were used to screen a cohort of sixty-five patients who had previously tested negative for all other known dystonia-associated genes. Results: We identified fourteen patients (21.5%) carrying KMT2B variants, of which one was classified as a Variant of Unknown Significance (VUS). We also identified two additional patients carrying pathogenic mutations in GNAO1 and ATM. Overall, we established a definitive genetic diagnosis in 23% of cases. We observed a spectrum of clinical manifestations in KMT2B variant carriers, ranging from generalized dystonia to short stature or intellectual disability alone, even within the same family. In 78.5% of cases, dystonia involved the lower limbs at onset, with later caudo-cranial generalization. Eight patients underwent pallidal Deep Brain Stimulation with a median decrease of BFMDRS-M score of 38.5% in the long term. We also report four asymptomatic carriers, suggesting that some KMT2B mutations may be associated with incomplete disease penetrance. Conclusions: KMT2B mutations are frequent in childhood-onset dystonia and cause a complex neurodevelopmental syndrome often featuring growth retardation and intellectual disability as additional phenotypic features. A dramatic and long-lasting response to Deep Brain Stimulation is characteristic of DYT-KMT2B dystonia

Discovery and functional prioritization of Parkinson's disease candidate genes from large-scale whole exome sequencing.

BACKGROUND: Whole-exome sequencing (WES) has been successful in identifying genes that cause familial Parkinson's disease (PD). However, until now this approach has not been deployed to study large cohorts of unrelated participants. To discover rare PD susceptibility variants, we performed WES in 1148 unrelated cases and 503 control participants. Candidate genes were subsequently validated for functions relevant to PD based on parallel RNA-interference (RNAi) screens in human cell culture and Drosophila and C. elegans models. RESULTS: Assuming autosomal recessive inheritance, we identify 27 genes that have homozygous or compound heterozygous loss-of-function variants in PD cases. Definitive replication and confirmation of these findings were hindered by potential heterogeneity and by the rarity of the implicated alleles. We therefore looked for potential genetic interactions with established PD mechanisms. Following RNAi-mediated knockdown, 15 of the genes modulated mitochondrial dynamics in human neuronal cultures and four candidates enhanced α-synuclein-induced neurodegeneration in Drosophila. Based on complementary analyses in independent human datasets, five functionally validated genes-GPATCH2L, UHRF1BP1L, PTPRH, ARSB, and VPS13C-also showed evidence consistent with genetic replication. CONCLUSIONS: By integrating human genetic and functional evidence, we identify several PD susceptibility gene candidates for further investigation. Our approach highlights a powerful experimental strategy with broad applicability for future studies of disorders with complex genetic etiologies

Political legacy of South Africa affects the plant diversity patterns of urban domestic gardens along a socio-economic gradient

Socioeconomic and cultural influences within the study area influenced plant diversity patterns, showing higher species richness in the more affluent, white-dominated suburbs. However, much of the plant diversity of affluent suburbs is made up of alien species, whereas utilitarian and indigenous plants are strongly associated with the lower socio-economic status of black suburbs. This study provides evidence of the effects that socio-economic factors can have on vegetation patterns, rather than ecological factors, which are more often investigated. Anthropogenic influences are one of the most dominant and persistent driving forces of species richness within urban areas

Separation of zirconium and hafnium by extraction with 2-octanol

Zirconium and hafnium are shown to be separable using 2-octanol (C8H18O) as an extractant. Zirconium basic carbonate was dissolved using hydrochloric acids at concentrations ranging from 5 % to 20 %. Potassium fluoride was found to be crucial to the process. Its effect was investigated in the concentration range of 1 M to 3 M. The optimum conditions obtained for extraction were 10 wt % HCl in a 1.5 M KF solution, a contact time of 15 minutes, and 100 % 2-octanol. Under these conditions, the separation factor of zirconium and hafnium is 9.2 with a maximum extraction percentage of 96.58 % of zirconium. The optimum conditions for stripping of zirconium were found to be 3 M H2SO4 as stripping agent, an A/O ratio of 1:1 and 40 minutes contact time. The McCabe-Thiele diagrams constructed from the experimental data indicate that four and five equilibrium stages are sufficient for the extraction and stripping of zirconium respectively. A recovery of 97.25 % of hafnium was obtained using a mixture of oxalic acid and nitric acid as a stripping agent. A study of chemical speciation in the two phases would be important for the improvement of the process.The University of Pretoria, the South African Research Foundation (NRF) and the Advanced Metals Initiative of the Department of Science and Technology.http://www.cetjournal.itam2020Chemical Engineerin

A novel TBK1 mutation in a family with diverse frontotemporal dementia spectrum disorders

Mutations in the TANK-binding kinase 1 (TBK1) gene have recently been shown to cause frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). The phenotype is highly variable and has been associated with behavioral variant FTD, primary progressive aphasia, and pure ALS. We describe the clinical, anatomical, and pathological features of a patient who developed corticobasal syndrome (CBS)/progressive nonfluent aphasia (PNFA) overlap. The patient presented with progressive speech difficulties and later developed an asymmetric akinetic–rigid syndrome. Neuroimaging showed asymmetrical frontal atrophy, predominantly affecting the right side. There was a strong family history of neurodegenerative disease with four out of seven siblings developing either dementia or ALS in their 50s and 60s. The patient died at the age of 71 and the brain was donated for postmortem analysis. Histopathological examination showed frontotemporal lobar degeneration TDP-43 type A pathology. Genetic screening did not reveal a mutation in the GRN, MAPT, or C9orf72 genes, but exome sequencing revealed a novel p.E703X mutation in the TBK1 gene. Although segregation data were not available, this loss-of-function mutation is highly likely to be pathogenic because it is predicted to disrupt TBK1/optineurin interaction and impair cellular autophagy. In conclusion, we show that TBK1 mutations can be a cause of an atypical parkinsonian syndrome and screening should be considered in CBS patients with a family history of dementia or ALS.Ruth Lamb, Jonathan D. Rohrer, Raquel Real, Steven J. Lubbe, Adrian J. Waite ... Tamas Revesz ... et al