Cassiterite oxygen isotopes in magmatic-hydrothermal systems: in situ microanalysis, fractionation factor, and applications

Tin and tungsten are important metals for the industrializing society. Deciphering the origin and evolution of hydrothermal fluids responsible for their formation is critical to underpin genetic models of ore formation. Traditional approaches obtain isotopic information mainly from bulk analysis of both ore and gangue minerals, or less frequently from in situ analysis of gangue minerals, which either bear inherited complexities and uncertainties or are indirect constraints. Hence, directly obtaining isotopic information from ore minerals such as cassiterite by in situ techniques is warranted. However, this has been hampered by challenges from both analytical and applicational aspects. In this study, we first demonstrate a lack of crystallographic orientation effects during cassiterite ion microprobe oxygen isotope analysis. Along with our newly developed matrix-matched reference material, the Yongde-Cst, which has a recommended δ18O value of 1.36 ± 0.16‰ (VSMOW) as defined by gas source isotope ratio mass spectrometry, in situ oxygen isotope analysis of cassiterite now is possible. We further refine the oxygen isotope fractionation (1000 ln α) for quartz-cassiterite by first-principles calculations, which is given by the equation of 1.259 × 106/T2 + 8.15 × 103/T − 4.72 (T is temperature in Kelvin). The 1000 ln α for quartz-cassiterite has a sensitive response to temperature, and makes cassiterite-quartz an excellent mineral pair in oxygen isotope thermometry, as described by the equation of T (℃) = 2427 × (δ18Oqtz − δ18Ocst)−0.4326 − 492.4. Using the well-established 1000 ln α of quartz-water, 1000 ln α of cassiterite-water is derived as 2.941 × 106/T2 − 11.45 × 103/T + 4.72 (T in Kelvin), which shows a weak response to temperature. This makes cassiterite an ideal mineral from which to derive δ18O of fluids as robust temperature estimates are no longer a prerequisite. We have applied oxygen isotope analysis to cassiterite samples from six Sn(-W) deposits in China. The results show considerable variability in δ18O values both within a single deposit and among studied deposits. Combining the δ18O of cassiterite samples and the equilibrium oxygen isotope fractionation, we find that the δ18O values of ore-forming fluids show a strong magmatic affinity with variable but mostly no to low degree involvements (~0-10%) of meteoric water, hence our results invite a reassessment on the extent and role of meteoric water in Sn-W mineralization. This study demonstrates that in situ oxygen isotope analysis of cassiterite is a promising tool to refine sources of ore-forming fluids, and to decode hydrothermal dynamics controlling tin and tungsten mineralization

Salt reduction policy for out of home sectors: a supplementary document for the salt reduction strategy to prevent and control non-communicable diseases (NCDS) in Malaysia 2021-2025.

Cardiovascular diseases (CVDs) are the major cause of death among Malaysians. Reduction of salt intake in populations is one of the most cost-effective strategies in the prevention of CVDs. It is very feasible as it requires low cost for implementation and yet could produce a positive impact on health. Thus, salt reduction initiatives have been initiated since 2010, and two series of strategies have been launched. However, there are issues on its delivery and outreach to the target audience. Further, strategies targeting out of home sectors are yet to be emphasized. Our recent findings on the perceptions, barriers and enablers towards salt reduction among various stakeholders including policy-makers, food industries, food operators, consumers and schools showed that eating outside of the home contributed to high salt intake. Foods sold outside the home generally contain a high amount of salt. Thus, this supplementary document is being proposed to strengthen the Salt Reduction Strategy to Prevent and Control Non-communicable Diseases (NCDs) for Malaysia 2021-2025 by focussing on the strategy for the out-of-home sectors. In this supplementary document, the Monitoring, Awareness and Product (M-A-P) strategies being used by the Ministry of Health (MOH) are adopted with a defined outline of the plan of action and indicators to ensure that targets could be achieved. The strategies will involve inter-sectoral and multi-disciplinary approaches, including monitoring of salt intake and educating consumers, strengthening the current enforcement of legislation on salt/sodium labelling and promoting research on reformulation. Other strategies included in this supplementary document included reformulation through proposing maximum salt targets for 14 food categories. It is hoped that this supplementary document could strengthen the current the Salt Reduction Strategy to Prevent and Control NCDs for Malaysia 2021-2025 particularly, for the out-of-home sector, to achieve a reduction in mean salt intake of the population to 6.0 g per day by 2025

Selective oxidation of propane to acrolein over MoPO/SiO2 catalyst

The selective oxidation of propane to acrolein over the MoPO/SiO2 catalyst has been studied. MoO/SiO2 exhibits only activity for the oxidative dehydrogenation of propane to propene. The propane conversion and acrolein selectivity are evidently increased by the addition of P to MoO/SiO2. The catalysts were characterized by XRD, Raman spectroscopy, H-2-TPR, NH3-TPD and FT-IR spectroscopy. The XRD and Raman results show that crystalline MoO3 is dominant on the silica-supported molybdenum oxide catalyst, while polymolybdate species are present on P-doped catalysts. Compared to the P-O-P stretching vibration at 905 cm(-1) in PO/SiO2, the P-doped sample exhibits the Raman band of the asymmetric PO4 stretching mode at 1085 cm(-1). Therefore, Mo-O-P bonds are likely to be formed on the P-doped catalyst, and the active sites are isolated by the phosphorus in MOPO/SiO2, preventing the growth of crystallized MoO3. These changes in structure and thus the improvement in reducibility of the MoPO/SiO2 catalyst may be responsible for the increase in propane conversion and acrolein selectivity. Furthermore, the results of FT-IR spectroscopy of pyridine adsorption and NH3-TPD show that both Bronsted and Lewis acid sites on the surface of the P-doped sample are stronger than those on MoO/SiO2. These suggest that the addition of phosphorus modifies the surface structure and enhances the surface acidity of the supported catalyst, thus improving the behavior of the catalyst

Genome structure of cotton revealed by a genome-wide SSR genetic map constructed from a BC1 population between gossypium hirsutum and G. barbadense

<p>Abstract</p> <p>Background</p> <p>Cotton, with a large genome, is an important crop throughout the world. A high-density genetic linkage map is the prerequisite for cotton genetics and breeding. A genetic map based on simple polymerase chain reaction markers will be efficient for marker-assisted breeding in cotton, and markers from transcribed sequences have more chance to target genes related to traits. To construct a genome-wide, functional marker-based genetic linkage map in cotton, we isolated and mapped expressed sequence tag-simple sequence repeats (EST-SSRs) from cotton ESTs derived from the A₁, D₅, (AD)₁, and (AD)₂genome.</p> <p>Results</p> <p>A total of 3177 new EST-SSRs developed in our laboratory and other newly released SSRs were used to enrich our interspecific BC₁genetic linkage map. A total of 547 loci and 911 loci were obtained from our EST-SSRs and the newly released SSRs, respectively. The 1458 loci together with our previously published data were used to construct an updated genetic linkage map. The final map included 2316 loci on the 26 cotton chromosomes, 4418.9 cM in total length and 1.91 cM in average distance between adjacent markers. To our knowledge, this map is one of the three most dense linkage maps in cotton. Twenty-one segregation distortion regions (SDRs) were found in this map; three segregation distorted chromosomes, Chr02, Chr16, and Chr18, were identified with 99.9% of distorted markers segregating toward the heterozygous allele. Functional analysis of SSR sequences showed that 1633 loci of this map (70.6%) were transcribed loci and 1332 loci (57.5%) were translated loci.</p> <p>Conclusions</p> <p>This map lays groundwork for further genetic analyses of important quantitative traits, marker-assisted selection, and genome organization architecture in cotton as well as for comparative genomics between cotton and other species. The segregation distorted chromosomes can be a guide to identify segregation distortion loci in cotton. The annotation of SSR sequences identified frequent and rare gene ontology items on each chromosome, which is helpful to discover functions of cotton chromosomes.</p

Landscape Composition and Spatial Prediction of Alveolar Echinococcosis in Southern Ningxia, China

In humans, larvae of the fox tapeworm Echinococcus multilocularis typically infect the liver where metastasis, calcification and necrosis cause the zoonotic disease alveolar echinococcosis (AE). Treatment is difficult. Early detection greatly increases patient life expectancy but under-detection is a problem. Understanding the ecological conditions that elevate AE risk would help identify at-risk communities. Voles and lemmings of the subfamily Arvicolinae are important intermediate hosts in most AE endemic areas, and arvicoline habitat has been proposed as a predictor of AE risk. Using a model of spatial autocorrelation with land cover identified from satellite remote sensing imagery, we identified AE hotspots in southern Ningxia Hui Autonomous Region (NHAR), China. Hotspots were not located near optimal arvicoline habitats. Thus, non-arvicolines provide principal reservoirs in NHAR and the range of ecological conditions sustaining E. multilocularis transmission in China is greater than previously thought. We also show: social factors explain higher prevalence in females than males; dogs increase infection risk; and we argue that water source quality is important via interaction with other environmental variables. Our map of AE prevalence represents the current state-of-the-art regarding the spatial distribution of AE in southern NHAR and provides an important baseline for future monitoring programs there

The Congenital Cataract-Linked G61C Mutation Destabilizes γD-Crystallin and Promotes Non-Native Aggregation

γD-crystallin is one of the major structural proteins in human eye lens. The solubility and stability of γD-crystallin play a crucial role in maintaining the optical properties of the lens during the life span of an individual. Previous study has shown that the inherited mutation G61C results in autosomal dominant congenital cataract. In this research, we studied the effects of the G61C mutation on γD-crystallin structure, stability and aggregation via biophysical methods. CD, intrinsic and extrinsic fluorescence spectroscopy indicated that the G61C mutation did not affect the native structure of γD-crystallin. The stability of γD-crystallin against heat- or GdnHCl-induced denaturation was significantly decreased by the mutation, while no influence was observed on the acid-induced unfolding. The mutation mainly affected the transition from the native state to the intermediate but not that from the intermediate to the unfolded or aggregated states. At high temperatures, both proteins were able to form aggregates, and the aggregation of the mutant was much more serious than the wild type protein at the same temperature. At body temperature and acidic conditions, the mutant was more prone to form amyloid-like fibrils. The aggregation-prone property of the mutant was not altered by the addition of reductive reagent. These results suggested that the decrease in protein stability followed by aggregation-prone property might be the major cause in the hereditary cataract induced by the G61C mutation