The Qingtonggou deposit is the largest Hg-Sb deposit in the Qinling orogenic belt, but the deposit genesis remains unclear. Fluid inclusion study indicates that the homogenization temperature range from 139.9 °C to 217 °C and the salinities vary from 0.7 to 2.1 wt% (NaCleq). The δ13C value in ore-stage calcite is from-7.6 ‰ to −7.1 ‰, and the δ18OSMOW value is between 13.6 ‰ and 15.3 ‰. The δ18OV-SMOW value in hydrothermal quartz is from 21.5 ‰ to 24.8 ‰, and the δD value is between −138 ‰ to −99 ‰. The δ34SV-CDT value range from 4 ‰ to 11.6 ‰, the 206Pb/204Pb values range from 18.0351 to 18.5080, the 207Pb/204Pb values range from 15.6390 to 15.6672, and the 208Pb/204Pb values range from 38.1586 to 38.4128. The hydrothermal calcite Sm-Nd isochron age for ore-stage calcite is 98.02 ± 0.42 Ma. The Hg-Sb mineralization is controlled by tectonic space formed by the left strike-slip fault, the ore-forming fluid has the characteristics of medium–low temperature, low density, and supergene mineralization, the ore-forming fluid comes from meteoric water and formation water, the ore-forming material comes from the stratum and basement of Yaolinghe group and Lower Cambrian, the Hg-Sb mineralization occurred at early Late Cretaceous. The complete metallogenic process is that the Yaolinghe Group and Lower Cambrian in this area are the source areas for Hg-Sb mineralization, the subsequent high background values Hg and Sb strata which received the denudation deposit of the source bed all contributed ore-forming materials, with the Qinling collision orogeny and extrusion in the Indosinian period and the continuous contraction of the Paleozoic basin, porous meteoric water and formation water extracted the ore-forming materials in source bed, formed ore-forming fluids, during the strike-slip process in intracontinental environment, deep and large faults provide a channel for the upward discharge of ore-forming fluids, with the decrease of fluid temperature, sulfide precipitation occurs in secondary fracture.
Abstract Pyrite (FeS2), the most abundant sulfide mineral on Earth, typically contains a host of minor and trace elements, including As, Co, Ni, and Au. It is an important semiconductor with unique structural properties markedly influenced by elemental impurities. However, whether the change in semiconducting properties of natural pyrite is caused by the type and concentration of trace elements or by a non-stoichiometry-related doping mechanism remains uncertain. Moreover, the effect of semiconducting properties on the enrichment mechanism of Au has not been well addressed. Here, we investigate microscopic pyrite crystals from the Heilangou gold field (HGF) in the eastern Jiaodong Peninsula using field emission scanning electron microscopy (SEM), electron probe microanalysis (EPMA), in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), potential-Seebeck microprobe (PSM), and thermoelectric measurements. The results demonstrate that pyrite grains show either p- or n-type conductivity depending on chemical compositions. Pyrite enriched in As, which typically substitutes for S in the crystal structure, tends to be p-type with a positive Seebeck coefficient, whereas pyrite crystals enriched in Co, Ni, Cu, and Zn, as well as those depleted in As, are typically n-type. Moreover, As shows the strongest influence on the semiconducting properties of natural pyrite crystals and a strong positive correlation with Au. We observed that visible Au grains are preferentially accumulated on individual domains of sulfides (e.g., As-rich pyrite) that act as cathodes, suggesting that electrical p-n junctions in sulfides drive electrochemical reactions with ore-forming fluids, resulting in the deposition of visible Au. The electrochemical precipitation mechanism of Au may account for the formation of other types of hydrothermal Au deposits.
Nano-micro calcium carbonate has a small particle size, uniform distribution, and good dispersion performance, offering great research value and development prospects. It has been widely used as a filler material for rubber, paper, ink, pigments, and coatings. Developing an efficient and controllable approach to preparing nano-micro calcium carbonate with adjustable morphology and controllable size has significant economic and environmental benefits. This study reports the controllable synthesis of nano-micro calcium carbonate meditated by additive engineering. The effects of various additives including inorganic acids, organic acids, alcohol, and surfactants on the particle size and morphology of the prepared materials were investigated. SEM, FT-IR and other characterization methods were used to analyze the prepared nano-micro calcium carbonate particle size, dispersion, and uniformity. The results showed that the particle size of calcium carbonate was 4~7 μm with a cubic structure. The particle size of calcium carbonate prepared by adding surfactant additives is in the range of 1~4 μm, and the crystal shape of calcium carbonate changes from calcite to vaterite after adding sodium dodecyl benzene sulfonate. With the aid of additives, the calcium carbonate particles dispersed more evenly. The mechanism of the controllable synthesis of nano-micro calcium carbonate mediated by additive engineering is elucidated and discussed. SDBS was found to be the best additive for preparing nano-micro calcium carbonate, and the synthesis conditions were explored and optimized.
Sodium-ion batteries are applicable in cost-sensitive fields like grid electricity storage systems due to the widely distributed of sodium reserves. Hard carbons currently stand out as the most promising anode for practical sodium-ion batteries, but their performance and economy require improvement. In this work, we successfully developed spherical hard carbons through controlled pyrolysis of starch. Starch has an attractive natural spherical morphology, but direct pyrolysis leads to the cracking of spherical structure caused by the rapid release of small molecules. To address this issue, we employed an additive-free "stablization process" to establish a stable structure prior to pyrolysis. The underlying principle of this "stablization process" has been clarified: preheating starch below its melting point prompts partial thermal decomposition, preventing structural meltdown during subsequent decomposition. The resulting hard carbon, obtained through controlled pyrolysis, exhibits a high tap density exceeding 1 g cm -3 and the optimal reversible capacity reaches 321 mAh g -1 with an outstanding initial columb efficiency of 88% at 30 mA g -1 . Furthermore, its practical application was validated via multi–layer pouch cells. When coupled with Na 2 Fe(SO 4 ) 2 cathode, the pouch cell demonstrated a cycle life approaching 1000 cycles, surpassing all starch-based hard carbons reported thus far. This work guides an efficient approach for fabricating high–performance, remarkably economical hard carbon anodes for practical application of sodium-ion batteries.
Summary The abilities of broccoli seed extracts and purified sulforaphane ( SF ) to scavenge 2,2′‐azinobis [3‐ethylbenzothiazoline‐6‐sulphonate] ( ABTS •+ ), 2,2‐diphenyl‐1‐picrylhydrazyl ( DPPH • ) and superoxide anions were studied. The free radical scavenging activities of broccoli seed extracts had no exact correlation with SF content, indicating that SF was not the main antioxidant component. The broccoli seed extracts were separated by high‐speed countercurrent chromatography to obtain purified SF , which showed dose‐dependent free radical scavenging activities in the DPPH • and ABTS •+ assays, but its activities were weaker to those of ascorbic acid. The same trend was observed in the chemiluminescence assay. The results showed that broccoli seed extracts had strong free radical scavenging activities that were not attributable to SF .
After consuming broccoli, isothiocyanates can be produced by the hydrolytic action of myrosinase from plant and/or microbiota. Using male C57BL/6 mice, the present study investigated the effects of broccoli ingestion on the myrosinase-like activity, NAD(P)H:quinone oxidoreductase 1 (NQO1) activity, diversity and composition of the gut microbiota. Compared with the control group, continuously feeding raw or hydrolysed broccoli increased the myrosinase-like activities of the colon and caecum contents, and also improved the NQO1 activity of the colon mucosa. Significant difference between the broccoli and control feeding groups were found. 16S rRNA gene sequencing indicated that broccoli ingestion profoundly affected the composition of the gut bacteria community. The correlation between the gut bacterial community composition and microbiota myrosinase-like activity was also studied. However, one type of glucosinolate, sinigrin, had no effect on these activities, indicating that broccoli component(s), other than glucosinolate, had increased the NQO1 and myrosinase-like activities.
This study sought to investigate the historical background taking place the buildup concept of lifelong learning in Bangladesh and the learning society.It makes the knowledge center medium a possible institutional standard for the implementation of adult lifelong learning in Bangladesh.Implications of the knowledge center as a standard for lifelong learning in Bangladesh are explain by means of the container of representation on similarities as well as comparison with China.Eventually, lifelong knowledge education from the current study of the Asia-Pacific region are reviewed with regard to the advancement of strategic objectives aim to deliver adult and lifelong learning in Bangladesh point of view through and across the medium knowledge of society.
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