Role of tannin pretreatment in flotation separation of magnesite and dolomite

Flotation separation of magnesite and its calcium-containing carbonate minerals is a difficult problem.Recently,new regulat-ors have been proposed for magnesite flotation decalcification,although traditional regulators such as tannin,water glass,sodium carbon-ate,and sodium hexametaphosphate are more widely used in industry.However,they are rarely used as the main regulators in research because they perform poorly in magnesite and dolomite single-mineral flotation tests.Inspired by the limonite presedimentation method and the addition of a regulator to magnesite slurry mixing,we used a tannin pretreatment method for separating magnesite and dolomite.Microflotation experiments confirmed that the tannin pretreatment method selectively and largely reduces the flotation recovery rate of dolomite without affecting the flotation recovery rate of magnesite.Moreover,the contact angles of the tannin-pretreated magnesite and dolomite increased and decreased,respectively,in the presence of NaOl.Zeta potential and Fourier transform infrared analyses showed that the tannin pretreatment method efficiently hinders NaOl adsorption on the dolomite surface but does not affect NaOl adsorption on the magnesite surface.X-ray photoelectron spectroscopy and density functional theory calculations confirmed that tannin interacts more strongly with dolomite than with magnesite.

聚吡咯@二氧化锰/碳纳米管薄膜电极的制备及在高性能锌离子电池中的应用

中性/弱酸性水系锌锰电池因其能量密度高、价格低廉、环境友好等优势受到广泛关注。然而,现有的二氧化锰正极材料存在导电性能差,在充放电过程中易于溶解等问题。这严重影响了电池的倍率性能和循环稳定性,阻碍了中性锌锰电池的应用。为了解决上述问题,本文设计了以碳纳米管(CNT)网络薄膜为导电基底沉积聚吡咯(PPy)包覆二氧化锰(PPy@MnO_(2)/CNT)的多级结构电极。碳纳米管和聚吡咯组装形成高比表面积的三维交联导电网络,为活性材料提供了快速的电子、离子传输通道;聚吡咯包覆纳米级二氧化锰能够有效地抑制二氧化锰的溶解,进而提升电池的倍率特性和循环稳定性。以PPy@MnO_(2)/CNT作为正极材料组装的水系锌锰电池在1 A·g^(-1)的电流密度下,比容量达到210 mAh·g^(-1),循环1000圈后,电池依然具有较高的容量保持率(85.7%)。本工作的导电聚合物包覆活性物质的策略可为发展高稳定柔性储能器件提供新思路。

miR-103-3p regulates the differentiation of bone marrow mesenchymal stem cells in myelodysplastic syndrome

The pathogenesis of myelodysplastic syndrome(MDS)may be related to the abnormal expression of microRNAs(miRNAs),which could influence the differentiation capacity of mesenchymal stem cells(MSCs)towards adipogenic and osteogenic lineages.In this study,exosomes from bone marrow plasma were successfully extracted and identified.Assessment of miR-103-3p expression in exosomes isolated from BM in 34 MDS patients and 10 controls revealed its 0.52-fold downregulation in patients with MDS compared with controls(NOR)and was downregulated 0.55-fold in MDS-MSCs compared with NOR-MSCs.Transfection of MDS-MSCs with the miR-103-3p mimic improved osteogenic differentiation and decreased adipogenic differentiation in vitro,while inhibition of miR-103-3p showed the opposite results in NOR-MSCs.Thus,the expression of miR-103-3p decreases in MDS BM plasma and MDS-MSCs,significantly impacting MDS-MSCs differentiation.The miR-103-3p mimics may boost MDS-MSCs osteogenic differentiation while weakening lipid differentiation,thereby providing possible target for the treatment of MDS pathogenesis.

Investigation of the flotation behavior and interaction characteristics of micro-fine quartz and magnesite in a dodecylamine system under ultrasonic treatment

Ultrasonic treatment,as an important surface modification method,profoundly affects the flotation behavior of minerals.This study examined the impact of ultrasonic treatment on the surface properties and flotation performance of magnesite and quartz in a dodecylamine(DDA)flotation system.Atomic force microscope detection results revealed that the surface roughness and roughness size of both magnesite and quartz increased after ultrasonic treatment.Flotation tests indicated that the recovery rates of magnesite and quartz were lower after ultrasonic treatment.At pH of 10 and DDA of 75 mg/L,ultrasonic treatment led to a 0.66%,3.46%,and 0.33%decrease in the flotation recovery rates for three different magnesite particle sizes.Following ultrasonic processing,the flotation recovery rates for three different quartz particle sizes decreased by 8.48%,30.76%,and 43.69%,in that order.X-ray photoelectron spectroscopy detection results showed an increased presence of characteristic Mg and Si sites on the surfaces of magnesite and quartz following ultrasonic treatment.DDA acted on the surfaces of the two minerals through electrostatic adsorption and hydrogen bonding adsorption and repelled the flotation of minerals owing to the same charge as characteristic sites,thereby reducing flotation recovery.Adsorption capacity tests and contact angle measurements demonstrated a decrease in DDA adsorption and contact angle on the surfaces of magnesite and quartz after ultrasonic treatment,explaining the reduced floatability.Extended Derjaguin–Landau–Verwey–Overbeek theoretical calculations indicated that before ultrasonic treatment,there was a repulsive energy between magnesite and fine-grained quartz particles.After ultrasonic treatment,the interaction energy between magnesite and fine quartz particles is mutual attraction.

Advances in liver engineering with cell, scaffold, and vascularization

Liver tissue engineering is a promising alternative to organ transplantation for the treatment of end-stage liver disease,acute liver failure,and liver-based metabolic disorders.This review discusses the current progress and obstacles in tissue engineering of cell sources,biomaterials,and vascularization strategies,which are key to constructing functional liver tissues.Significant progress has been made in developing available cell sources,tunable biomaterials,and integrating vascular networks.However,challenges remain in replicating the complex architecture and function of the liver.Further research is required to overcome these hurdles and ultimately realize the full potential of tissue-engineered liver constructs in clinical applications.

Mechanistic understanding of Cu-based bimetallic catalysts

Copper has received extensive attention in the field of catalysis due to its rich natural reserves,low cost,and superior catalytic performance.Herein,we reviewed two modification mechanisms of co-catalyst on the coordination environment change of Cu-based catalysts:(1)change the electronic orbitals and geometric structure of Cu without any catalytic functions;(2)act as an additional active site with a certain catalytic function,as well as their catalytic mechanism in major reactions,including the hydrogenation to alcohols,dehydrogenation of alcohols,water gas shift reaction,reduction of nitrogenous compounds,electrocatalysis and others.The influencing mechanisms of different types of auxiliary metals on the structure-activity relationship of Cu-based catalysts in these reactions were especially summarized and discussed.The mechanistic understanding can provide significant guidance for the design and controllable synthesis of novel Cu-based catalysts used in many industrial reactions.

High‑Temperature‑Tolerant Artificial Muscles Using Poly(p‑phenylene benzobisoxazole)Composite Yarns

Today the developed yarn muscles or actuators still cannot satisfy the requirements of working in high-temperature environ-ments.Thermal resistivity is highly needed in aerospace and industrial protection applications.Herein,an artificial muscle with high-temperature tolerance is prepared using carbon nanotube(CNT)wrapped poly(p-phenylene benzobisoxazole)(PBO)composite yarns.A thermal twisting method was utilized to reorientate the stiff PBO molecular chains into a uniform and twist-stable coiled structure.The CNT/PBO composite yarn muscle generates reversible contractile strokes up to 18.9%under 5.4 MPa tension and outputs 1.3 kJ kg^(-1) energy density.In contrast to previous actuators,which are normally oper-ated at room temperatures,the CNT/PBO composite yarn muscles can work at ambient temperatures up to 300℃ with high contractile stroke and long-term stability.A bionic inchworm robot,a deployable structure,and smart textiles driven by the high-temperature-tolerant yarn muscles were demonstrated,showing the promise as a soft actuator towards high-temperature environment applications.

High-performance carbon nanotube/polyaniline artificial yarn muscles working in biocompatible environments

Implantable artificial muscles are of great importance for muscle function restoration and physical augmentation but are still challenging.Herein,we report an artificial muscle by soaking-polymerization of polyaniline(PANI)inside a carbon nanotube(CNT)yarn.Working in aqueous biocompatible solutions,the yarn muscle generates a large contractile stroke of 17%and high isometric stress of 8 MPa at voltages lower than 2 V.The excellent performance can be ascribed to the large actuation volume that is enabled by the fast electrochemical redox of PANI confined in a coiled yarn structure.The actuation performance outperforms that of previously reported aqueous artificial yarn muscles.Moreover,the yarn muscle can work well and maintain excellent actuating performance in other biocompatible solutions such as normal saline and Na2SO4 aqueous solution,which makes the CNT/PANI yarn muscles suitable for implantable bionic applications.Finally,a biomimetic arm was fabricated to demonstrate the applications of the CNT/PANI yarn artificial muscle in implantable muscle,underwater robots,and soft exoskeletons.

Effect of acid corrosion on the surface roughness and floatability of magnesite and dolomite

To modify surface roughness and improve flotation performance,hydrochloric acid etching pretreatment was performed on magnesite and dolomite.Flotation tests disclosed that acid corrosion improved the flotation kinetics and flotation recovery rates of magnesite and dolomite.Under pulp pH 10 and sodium oleate(NaOl)concentration 20 mg·L^(-1),the flotation recovery rates of magnesite and dolomite after acid etching increased by 31.05%and 29.20%,respectively,compared with those before acid etching.Adsorption density tests proved that the adsorption density of NaOl on magnesite and dolomite was higher after acid etching than before acid etching,implying that acid etching drives Naol adsorption.Zeta potential analysis revealed that acid etching reduces the point of zero charge of magnesite and dolomite.Atomic force microscopy and X-ray photoelectron spectroscopy results demonstrated that acid corrosion modified the surface roughness of magnesite and dolomite,increasing the magnesium(Mg)content on the magnesite surface and the calcium and Mg contents on the dolomite surface.Contact angle measurements indicated that acid corrosion slightly reduced the contact angle between magnesite and dolomite.With Naol present on the surface,the contact angles of magnesite and dolomite after acid etching significantly increased compared with those before acid etching.Therefore,acid etching is effective in improving the floatability of magnesite and dolomite.

Research advancement of efficient flotation separation technologies for magnesium-containing minerals

As high-grade magnesite and brucite resources(hereinafter referred to as magnesium-containing minerals)are decreasing annually,developing flotation separation technologies capable of efficiently and economically extracting magnesium resources from low-grade magnesium-containing minerals is necessary.Although efficient flotation separation technologies for magnesium-containing minerals are well researched,related concepts are not yet clarified.Moreover,the industrial development of magnesium-containing mineral flotation technologies is limited by their low separation efficiency and environmental problems.This limitation has inhibited the full utilization of low-grade magnesium-containing minerals.This study comprehensively discusses the research progress of flotation separation technologies for magnesium-containing minerals,focusing on the crystal chemical and surface characteristics of magnesium-containing minerals and their gangue minerals,effect of inevitable ions on mineral flotation behavior,interaction effects of minerals,and research advancement of flotation reagents.The study aims to clarify the future development direction of the flotation separation of magnesium-containing minerals and provide theoretical support and technical references for an efficient separation.