Comprehensive Recovery Process of Skarn Type Copper-sulfur Ore Resources

This is an article in the field of mineral processing engineering. For a skarn copper ore, the disseminated particle size is fine, the valuable elements in the ore are Cu, S, Fe and the associated element Ag. Compared with the effects of copper preferential flotation and copper-sulfur mixed flotation-copper-sulfur separation on the comprehensive recovery, the copper-sulfur mixed flotation-copper-sulfur separation process can achieve better recovery of copper, sulfur and silver, and magnetite has a certain recovery value. Copper concentrate with copper grade of 24.39% and copper recovery of 91.68% and sulfur concentrate with sulfur grade of 33.10% and sulfur recovery of 61.19% were obtained by copper sulfur mixed flotation. Ag was enriched in the copper concentrate, with a grade of 185 g/t and Ag recovery of 83.21%. The recovery of iron concentrate can be increased after the regrinding magnetic separation of flotation tailings. With two-stage weak magnetic separation, iron concentrate with iron grade of 56.48% and iron recovery of 33.84% can be obtained. The results can provide a reference for the similar copper sulfide

Study on the Characteristics of Soil Moisture of Artificial Robinia pseudoacacia Forest Land in Different Latitudinal Zones of Northern Shaanxi

This article studies the soil moisture conditions of 30 years artificial Robinia pseudoacacia in the north of Shaanxi under different climate conditions in order to explore the relationship between soil moisture and impact factor of Robinia pseudoacacia in this area, and variation characteristics of soil moisture in the Loess Plateau region. The results show that soil moisture content decreases with increase of soil depth, and in 40-50 cm depth the jump point of moisture reduction appears significantly. Soil moisture was lower than the growth critical moisture in 5 samples to the north of Chunhua, and has different degrees of deficit. Soil moisture deficit degree was more than 50% in sandy loam and light loam soils such as Yulin, Shenmu and Suide. With the increasing of latitude, both of soil accumulative storage and net rainfall tends to decrease, but the relationship between them is significant correlation, indicating that that climate conditions are the major factors causing significant difference of soil moisture

Characterization and evaluation of polysaccharide/konjac glucomannan blend hydrogel for wound healing

Bletilla striata polysaccharide (BSP) is effective for wound healing and has important applications in health care. A series of blend hydrogels was designed with BSP and konjac glucomannan (KGM) in this study to overcome the deficient mechanical performance caused by the excessive dissolution of BSP without affecting its physiological activity. The interplay between them, as well as the effects of KGM concentration on the physical properties and microstructures of hydrogels, were also explored. It was proved that the frame of the hydrogel was primarily formed by KGM. BSP was dispersed uniformly and linked to KGM through hydrogen bonding, which effectively improved the physical properties, such as increasing the water-holding capacity, improving the swelling degree, and enhancing the mechanical properties. Blend hydrogel BK2-2 (containing 1.0% BSP and 1.0% KGM, w/v) was found to be the optimal formulation based on the thermal stability and microstructure, which was used for further research. In vitro experiments revealed the L929 cell proliferative effects of the blend hydrogel, and no difference was found with BSP sponge extract after 72 h of exposure. In vivo animal studies indicated that the BK2-2 accelerated wound healing compared with the control group; however, no difference was found with dressings only made of BSP. These results demonstrated that KGM improved the physical properties of BSP-based material without negatively affecting its physiological properties. Also, the BSP/KGM blend hydrogel had good comprehensive properties and is expected to be used as a wound healing material in the future

Monsoon intra-seasonal variability in a high-resolution version of Met Office Global Coupled model

Intra-seasonal oscillation (ISO) is a key ingredient of the East Asia and western North Pacific (EAWNP) summer monsoon and particularly important for seasonal forecast. This paper evaluates the seasonal means and ISOs of the EAWNP summer monsoon simulated by the latest version of the Met Office Global Coupled Model (HadGEM3-GC2) with two different atmospheric model resolutions at ~130 and ~25 km coupled to a same 0.25° × 0.25° resolution ocean model. Results show that the mean states of sea surface temperature (SST), low-level specific humidity and the western Pacific subtropical high are all improved in HadGEM3-GC2 with higher atmosphere resolution. Moreover, although ISO variance is overestimated over the western North Pacific, the model has good fidelity in characterising ISO basic features over the EAWNP including the dominant EOF structure, northward propagation and cycle evolution, as well as the zonal displacement of western Pacific Subtropical High and South Asian High associated with the northward propagating ISOs. Increasing atmosphere model resolution yields improvements in most aspects of the Monsoon ISO over the EAWNP, especially for its northward propagation. Further analysis indicates that this improvement is mainly due to the better description of ISO-related air–sea interaction in higher resolution experiment, as evidenced by the enhanced intra-seasonal SST variance and more coherent northward propagation of rainfall, SST, and the associated surface dynamic and thermodynamic variables in the higher resolution model

Mapping of Soil Organic Carbon Stocks Based on Aerial Photography in a Fragmented Desertification Landscape

Northern China’s agropastoral ecotone has been a key area of desertification control for decades, and digital maps of its soil organic carbon (SOC) stocks are needed to reveal the gaps between the actual SOC levels and baseline to support land degradation neutrality (LDN) under the Sustainable Development Goals. However, reliable soil information is scarce, and accurate prediction is hindered by the fragmented landscape, which is a dominant characteristic of desertified land. To improve the patchiness identification and accuracy of SOC prediction, we conducted field surveys and collected low-altitude aerial images along the desertification degrees (severe and extremely severe, moderate, slight) in the Horqin Sandy Land. Linear regressions were performed on the relationships between the normalized difference vegetation index and the fractional vegetation cover (FVC) extracted from aerial images, and regression kriging was applied to predict SOC stocks based on the soil-forming factors (vegetation, climate, and topography). Our prediction and cross-validation showed that the fragmented structure and prediction accuracy of SOC stocks were both greatly improved for desertified land. The FVC (R2c = 0.94) and evapotranspiration (R2c = 0.86) had significant positive effects on SOC stocks, respectively, with indirect and direct causal relationships. Our results could provide soil information with better patchiness and accuracy to help policymakers determine the future LDN status in this fragmented desertification landscape. As drone technology becomes more available, it will fully support digital mapping of soil properties

Mapping of Soil Organic Carbon Stocks Based on Aerial Photography in a Fragmented Desertification Landscape

Northern China’s agropastoral ecotone has been a key area of desertification control for decades, and digital maps of its soil organic carbon (SOC) stocks are needed to reveal the gaps between the actual SOC levels and baseline to support land degradation neutrality (LDN) under the Sustainable Development Goals. However, reliable soil information is scarce, and accurate prediction is hindered by the fragmented landscape, which is a dominant characteristic of desertified land. To improve the patchiness identification and accuracy of SOC prediction, we conducted field surveys and collected low-altitude aerial images along the desertification degrees (severe and extremely severe, moderate, slight) in the Horqin Sandy Land. Linear regressions were performed on the relationships between the normalized difference vegetation index and the fractional vegetation cover (FVC) extracted from aerial images, and regression kriging was applied to predict SOC stocks based on the soil-forming factors (vegetation, climate, and topography). Our prediction and cross-validation showed that the fragmented structure and prediction accuracy of SOC stocks were both greatly improved for desertified land. The FVC (R2c = 0.94) and evapotranspiration (R2c = 0.86) had significant positive effects on SOC stocks, respectively, with indirect and direct causal relationships. Our results could provide soil information with better patchiness and accuracy to help policymakers determine the future LDN status in this fragmented desertification landscape. As drone technology becomes more available, it will fully support digital mapping of soil properties

Effects of canyon geometry on the distribution of traffic-related air pollution in a large urban area:Implications of a multi-canyon air pollution dispersion model

Street canyons are ubiquitous in urban areas. Traffic-related air pollutants in street canyons can adversely affect human health. In this study, an urban-scale traffic pollution dispersion model is developed considering street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. In the model, vehicle exhausts generated from traffic flows first disperse inside street canyons along the micro-scale wind field generated by computational fluid dynamics (CFD) model. Then, pollutants leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NOx and CO from traffic emissions were studied over the center of Beijing. We found that an increase in building height leads to heavier pollution inside canyons and lower pollution outside canyons at pedestrian level, resulting in higher domain-averaged concentrations over the area. In addition, canyons with highly even or highly uneven building heights on each side of the street tend to lower the urban-scale air pollution concentrations at pedestrian level. Further, increasing street widths tends to lead to lower pollutant concentrations by reducing emissions and enhancing ventilation simultaneously. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry while considering traffic demand as well as local weather patterns may significantly reduce inhalation of unhealthy air by urban residents

Percutaneous endoscopy in direct real-time observation of choke vessels in rat perforator flap model

Background: Most of the techniques used to investigate choke vessels are indirect. The aim of the present study is to assess the effectiveness of percutaneous endoscopy in direct real-time visualization of choke vessels in rat perforator flap models. Methods: A classic perforator flap on the rat dorsum was designed (n = 12). An additional incision was made to place the percutaneous endoscope. Evans blue dye was injected from the common carotid artery to distinguish choke arteries from veins. Blood perfusion status was assessed using full-field laser perfusion imaging (FLPI) and the oxygen/carbon dioxide levels. Photographs of choke vessels were taken and compared at 1 h, 1 day, 4 days, and 7 days postoperation. The flap survival area was examined on day 7. Results: The average survival rate of perforator flaps was 70.1 ± 10.8%. The choke arteries but not choke veins were stained blue after injection of Evans blue dye. The choke arteries constricted instantly after surgery, dilated to a maximum diameter on postoperation day 4, and returned to the preoperation status on day 7. The choke veins dilated instantly after the operation, reached their largest diameters on postoperation day 4, and remained dilated on day 7. The behaviors of choke vessels were consistent with the FLPI results and oxygen/carbon dioxide statuses. Conclusion: Percutaneous endoscopy can provide direct real-time visualization of choke vessels in living rat perforator flap models and enable the identification of choke arteries and veins. This novel technique represents an ideal platform for investigating choke vessels in perforator flap models. Keywords: Percutaneous endoscopy, Choke vessel, Visualization, Perforator flap mode

Morphology Evolution of TiO₂ Facets and Vital Influences on Photocatalytic Activity

Modulation of anatase toward highly active facets has been attracting much attention, but the mechanism and photoactivity are still ambiguous. Here we demonstrate the inherent mechanisms for facets nucleation and morphology evolution, and clarify some vital influences of facets and surface nature on the photoactivity. Simply tuning the Ti/F ratio in the synthetic mixture leads to single anatase crystal exposed with different facets like {001}, {010}, or {110}. And complex sphere structure exposed with {001} facets can be formed by secondary nucleation and growth. Prolonging the hydrothermal treatment time causes selective etching on {001} facets, whereas defluorination via thermal calcination produces many pores on the surface. The photodegradation of positively and negatively charged, and zwitterionic dyes indicates that the type of reactant, adsorption mode and surface area play significant roles in photocatalysis. This work makes a step toward understanding the formation of facet-mediated structure and designing highly active materials for environmental remediation, hydrogen production, and dye-sensitized solar cells