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Mechanistic insights into stepwise activation of malachite for enhancing surface reactivity and flotation performance

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2159-2172页

作者： Qicheng Feng Wanming Lu Han Wang Qian Zhang State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Faculty of Land Resource EngineeringKunming University of Science and TechnologyKunming 650093China Yunnan Key Laboratory of Green Separation and Enrichment of Strategic Mineral Resources Kunming University of Science and TechnologyKunming 650093China

Malachite is a common copper oxide mineral that is often enriched using the sulfidization-xanthate flotation ***,the direct sulfidization method cannot yield copper concentrate ***,a new sulfidization flotation process was developed to promote the efficient recovery of *** this study,Cu^(2+) was used as an activator to interact with the sample surface and increase its reaction sites,thereby strengthening the mineral sulfidization process and *** to single copper ion activation,the flota-tion effect of malachite significantly increased after stepwise Cu^(2+) *** potential,X-ray photoelectron spectroscopy(XPS),time-of-flight secondary ion mass spectroscopy(ToF-SIMS),scanning electron microscopy and energy dispersive spectrometry(SEM-EDS),and atomic force microscopy(AFM)analysis results indicated that the adsorption of S species was significantly enhanced on the mineral surface due to the increase in active Cu sites after Cu^(2+) stepwise ***,the proportion of active Cu-S spe-cies also increased,further improving the reaction between the sample surface and subsequent ***-transform infrared spec-troscopy(FT-IR)and contact angle tests implied that the xanthate species were easily and stably adsorbed onto the mineral surface after Cu^(2+) stepwise activation,thereby improving the hydrophobicity of the mineral ***,the copper sites on the malachite sur-face after Cu^(2+) stepwise activation promote the reactivity of the mineral surface and enhance sulfidization flotation of malachite.

关键词： malachite copper ions stepwise activation flotation mechanism enhanced sulfidization

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A new interacting capillary bundle model on the multiphase flow in micropores of tight rocks

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Petroleum science 2024年第2期21卷 1099-1112页

作者： Wen-Quan Deng Tian-Bo Liang Wen-Zhong Wang Hao Liu Jun-Lin Wu Fu-Jian Zhou National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China

Surfactants are widely used in the fracturing fluid to enhance the imbibition and thus the oil recovery rate. However, current numerical models cannot capture the physics behind capillary imbibition during the wettability alteration by surfactants. Although the interacting capillary bundle(ICB) model shows potential in characterizing imbibition rates in different pores during wettability alteration, the existing ICB models neglect the influence of wettability and viscosity ratio on the imbibition behavior, making it difficult to accurately describe the oil-water imbibition behavior within the porous media. In this work,a new ICB mathematical model is established by introducing pressure balance without assuming the position of the leading front to comprehensively describe the imbibition behavior in a porous medium under different conditions, including gas-liquid spontaneous imbibition and oil-water *** the pore size distribution of a tight rock is known, this new model can predict the changes of water saturation during the displacement process in the tight rock, and also determine the imbibition rate in pores of different sizes. The water saturation profiles obtained from the new model are validated against the waterflooding simulation results from the CMG, while the imbibition rates calculated by the model are validated against the experimental observations of gas-liquid spontaneous imbibition. The good match above indicates the newly proposed model can show the water saturation profile at a macroscopic scale while capture the underlying physics of the multiphase flow in a porous medium at a microscopic scale. Simulation results obtained from this model indicate that both wettability and viscosity ratio can affect the sequence of fluid imbibition into pores of different sizes during the multiphase flow, where less-viscous wetting fluid is preferentially imbibed into larger pores while more-viscous wetting fluid tends to be imbibed into smaller pores. Fur

关键词： Imbibition Multiphase flow Tight rock Interacting capillary bundle model Wettability

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Visible light promoted aerobic selective photo-oxidation of cyclohexene on LaCo_(x)Cu_(1−x)O_(3) catalyst

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Nano Research 2024年第8期17卷 6940-6950页

作者： Xu Guo Liru Song Wenyu Wang Fengfeng Li Minh Ngoc Ha Jun Tang Qiang Ling Ping Cui Qingping Ke College of Chemistry and Chemical Engineering Anhui University of TechnologyMaanshan 243000China VNU Key Laboratory of Advanced Material for Green Growth Faculty of ChemistryUniversity of ScienceVietnam National UniversityHanoi 100000Vietnam

Heterogeneously catalyzed liquid oxidation of olefins with O_(2) provides an alternative way for synthesizing high-value added ***,we report a straightforward urea-redox and sol-gel process for synthesizing LaCo_(x)Cu_(1−x)O_(3) for aerobic photooxidation of *** research highlights a marked increase in the proportions of Co^(2+) and Cu+species in a low chemical state,as well as enhanced visible light absorption through this *** investigations suggest that the catalytic process,particularly with LaCo_(0.7)Cu_(0.3)O_(3),involves a radical pathway mediated by reactive oxygen *** presence of Cu+/Co^(2+) species and surface oxygen vacancies is proposed to boost O_(2) adsorption and activation on the catalyst,facilitating the formation of ***,Cu^(2+)/Co^(3+) species are thought to aid in generating cyclohexenederived radical *** efficient aerobic oxidation of cyclohexene on LaCo_(0.7)Cu_(0.3)O_(3) catalyst relies on the formation of reactive oxygen species and carbon radicals,facilitated by its strong visible light *** achieves a cyclohexene conversion of 89.4% and selectivity to cyclohex-2-ene-1-one of 72.2%,along with stable recyclability after six *** creation of nano-structured LaCo_(x)Cu_(1−x)O_(3) through the urea-redox and sol-gel process offers a promising avenue for the development of highly efficient catalysts for the aerobic photo-oxidation of cyclohexene to cyclohex-2-ene-1-one in the future.

关键词： perovskite oxide photocatalysis oxidation cyclohexene LaCoCuO_(3) cyclohex-2-ene-1-one

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Numerical Study on the Effect of Gap Diffraction on the Hydrodynamic Performance of A Floating Breakwater

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china Ocean Engineering 2024年第4期38卷 663-675页

作者： BIAN Xiang-qian JI Chun-yan XU Sheng GUO Jian-ting HUO Fa-li School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China

Two-dimensional(2D)flume experiments are useful in investigating the performances of floating breakwaters(FBs),including hydrodynamic performances,motion responses,and mooring *** a reasonable gap between the flume wall and the FBs is a critical step in 2D flume ***,research on the effect of the gap on the accuracy of 2D FB experimental results is *** address this issue,a numerical wave tank is developed using CFD to estimate the wave-FB interaction of a moored dual-cylindrical FB,and the results are compared to experimental data from a previously published *** is good agreement between them,indicating that the numerical model is sufficiently *** numerical model is then applied to explore the effect of gap diffraction on the performance of FBs in2D *** was discovered that the nondimensional gap length L_(Gap)/W_(Pool)should be smaller than 7.5%to ensure that the relative error of the transmission coefficient is smaller than 3%.The influence of the gap is also related to the entering wave properties,such as the wave height and period.

关键词： floating breakwater diffraction effect gap hydrodynamic performance model experiments CFD numerical simulation

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Effect of speed humps on instantaneous traffic emissions in a microscopic model with limited deceleration capacity

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Chinese Physics B 2024年第6期33卷 413-420页

作者：胡宇晨李启朗刘军王君霞汪秉宏 School of Mathematics and Physics Anhui Jianzhu UniversityHefei 230601China School of Civil Engineering and Transportation Northeast Forestry UniversityHarbin 150040China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

As a common transportation facility, speed humps can control the speed of vehicles on special road sections to reduce traffic risks. At the same time, they also cause instantaneous traffic emissions. Based on the classic instantaneous traffic emission model and the limited deceleration capacity microscopic traffic flow model with slow-to-start rules, this paper has investigated the impact of speed humps on traffic flow and the instantaneous emissions of vehicle pollutants in a single lane situation. The numerical simulation results have shown that speed humps have significant effects on traffic flow and traffic emissions. In a free-flow region, the increase of speed humps leads to the continuous rise of CO_(2), NO_(X) and PM emissions. Within some density ranges, one finds that these pollutant emissions can evolve into some higher values under some random seeds. Under other random seeds, they can evolve into some lower values. In a wide moving jam region, the emission values of these pollutants sometimes appear as continuous or intermittent phenomenon. Compared to the refined Na Sch model, the present model has lower instantaneous emissions such as CO_(2), NO_(X) and PM and higher volatile organic components(VOC) emissions. Compared to the limited deceleration capacity model without slow-to-start rules, the present model also has lower instantaneous emissions such as CO_(2), NO_(X) and PM and higher VOC emissions in a wide moving jam region. These results can also be confirmed or explained by the statistical values of vehicle velocity and acceleration.

关键词： traffic emissions speed humps slow-to-start rules deceleration capacity

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Designing Symmetric Gradient Honeycomb Structures with Carbon‑Coated Iron‑Based Composites for High‑Efficiency Microwave Absorption

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Nano-Micro Letters 2024年第11期16卷 224-241页

作者： Yu Zhang Shu‑Hao Yang Yue Xin Bo Cai Peng‑Fei Hu Hai‑Yang Dai Chen‑Ming Liang Yun‑Tong Meng Ji‑Hao Su Xiao‑Juan Zhang Min Lu Guang‑Sheng Wang School of Chemistry Beihang UniversityBeijing 100191People’s Republic of China School of Electronics and Information Zhengzhou University of Light IndustryZhengzhou 450002People’s Republic of China School of Chemical Engineering Northeast Electric Power UniversityJilin 132000People’s Republic of China College of Chemistry and Materials Engineering Beijing Technology and Business UniversityBeijing 100048People’s Republic of China

The impedance matching of absorbers is a vital factor affecting their microwave absorption(MA)*** this work,we controllably synthesized Material of Institute Lavoisier 88C(MIL-88C)with varying aspect ratios(AR)as a precursor by regulating oil bath conditions,followed by one-step thermal decomposition to obtain carbon-coated iron-based *** the precursor MIL-88C(Fe)preparation conditions,such as the molar ratio between metal ions and organic ligands(M/O),oil bath temperature,and oil bath time,influenced the phases,graphitization degree,and AR of the derivatives,enabling low filler loading,achieving well-matched impedance,and ensuring outstanding MA *** MOF-derivatives 2(MD_(2))/polyvinylidene Difluoride(PVDF),MD_(3)/PVDF,and MD4/PVDF absorbers all exhibited excellent MA properties with optimal filler loadings below 20 wt%and as low as 5 wt%.The MD_(2)/PVDF(5 wt%)achieved a maximum effective absorption bandwidth(EAB)of 5.52 GHz(1.90 mm).The MD_(3)/PVDF(10 wt%)possessed a minimum reflection loss(RL_(min))value of−67.4 at 12.56 GHz(2.13 mm).A symmetric gradient honeycomb structure(SGHS)was constructed utilizing the high-frequency structure simulator(HFSS)to further extend the EAB,achieving an EAB of 14.6 GHz and a RL_(min) of−59.0 *** research offers a viable inspiration to creating structures or materials with high-efficiency MA properties.

关键词： MIL-88C(Fe) Fe/Fe_(3)O_(4)/Fe_(3)C@C Controllable preparation Symmetric gradient honeycomb structure Microwave absorbing

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The MYC2-PUB22-JAZ4 module plays a crucial role in jasmonate signaling in tomato

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Molecular Plant 2024年第4期17卷 598-613页

作者： Shaofang Wu Chaoyi Hu Changan Zhu Yanfen Fan Jie Zhou Xiaojia Xia Kai Shi Yanhong Zhou Christine H.Foyer Jingquan Yu Department of Horticulture Zijingang CampusZhejiang UniversityHangzhou 310058China Hainan Institute Zhejiang UniversityYazhou Bay Science and Technology CitySanya 572025China College of Horticulture Northwest Agriculture&Forestry UniversityXianyang 712100China School of Biosciences College of Life and Environmental SciencesUniversity of BirminghamEdgbaston B152TTUK Key Laboratory of Horticultural Plants Growth and Development Agricultural Ministry of ChinaZhejiang UniversityHangzhou 310058China

Jasmonates(JAs),a class of lipid-derived stress hormones,play a crucial role across an array of plant physiological processes and stress *** JA signaling is thought to rely predominantly on the degradation of specific JAZ proteins by SCF^(COI1),it remains unclear whether other pathways are involved in the regulation of JAZ protein ***,we report that PUB22,a plant U-box type E3 ubiquitin ligase,plays a critical role in the regulation of plant resistance against Helicoverpa armigera and other JA responses in *** COI1 physically interacts with JAZ1/2/5/7,PUB22 physically interacts with JAZ1/3/4/***22 ubiquitinates JAZ4 to promote its degradation via the 26S proteasome ***,we observed that pub22 mutants showreduced resistance to ***,whereas jaz4 single mutants and jaz1 jaz3 jaz4 jaz6 quadruple mutants have enhanced *** hypersensitivity of pub22 mutants to herbivores could be partially rescued by JAZ4 ***,we found that expression of PUB22 can be transcriptionally activated by MYC2,thus forming a positive feedback circuit in JA *** noticed that the PUB22-JAZ4 module also regulates other JA responses,including defense against ***,inhibition of root elongation,and anthocyanin *** together,these results indicate that PUB22 plays a crucial role in plant growth and defense responses,together with COI1-regulated JA signaling,by targeting specific JAZs.

关键词： PUB22 JAZ COI1 MYC2 JA signaling Solanum lycopersicum

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Novel damage constitutive models and new quantitative identification method for stress thresholds of rocks under uniaxial compression

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Journal of Central South University 2024年第8期31卷 2658-2675页

作者： Du, Kun Yi, Yang Luo, Xin-yao Liu, Kai Li, Peng Wang, Shao-feng School of Resources and Safety Engineering Central South University Changsha China Zhongnan Engineering Corporation Limited Power Construction Corporation of China Changsha China

Four key stress thresholds exist in the compression process of rocks, i. e., crack closure stress (σcc), crack initiation stress (σci), crack damage stress (σcd) and compressive strength (σc). The quantitative identifications of the first three stress thresholds are of great significance for characterizing the microcrack growth and damage evolution of rocks under compression. In this paper, a new method based on damage constitutive model is proposed to quantitatively measure the stress thresholds of rocks. Firstly, two different damage constitutive models were constructed based on acoustic emission (AE) counts and Weibull distribution function considering the compaction stages of the rock and the bearing capacity of the damage element. Then, the accumulative AE counts method (ACLM), AE count rate method (CRM) and constitutive model method (CMM) were introduced to determine the stress thresholds of rocks. Finally, the stress thresholds of 9 different rocks were identified by ACLM, CRM, and CMM. The results show that the theoretical stress - strain curves obtained from the two damage constitutive models are in good agreement with that of the experimental data, and the differences between the two damage constitutive models mainly come from the evolutionary differences of the damage variables. The results of the stress thresholds identified by the CMM are in good agreement with those identified by the AE methods, i.e., ACLM and CRM. Therefore, the proposed CMM can be used to determine the stress thresholds of rocks.

关键词： stress threshold acoustic emission damage constitutive model damage element quantitative method

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Efficient Preparation and Electrochemical Properties of BiOCl/Graphite by One-step Solvothermal Method

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Journal of Wuhan University of Technology(Materials science) 2024年第3期39卷 651-657页

作者：门丽娟 FEI Chi LIU An 陈春钰 ZHOU Jiankang JU Dianchun School of Metallurgy Engineering Jiangsu University of Science and TechnologyZhangjiagang 215600China

We used the surface-pretreated graphite paper(Gp)as a carrier and loaded BiOCl with high selectivity to Cl^(-)on its surface by solvothermal method to form BiOCl@Gp *** morphology,structure,and composition of the materials were characterized by scanning electron microscopy and nitrogen adsorption/desorption,and the results showed that the spherical BiOCl particles were uniformly dispersed on the surface of the Gp,forming a mesoporous BiOCl@Gp composite with a specific surface area of 22.82 m^(2)/g and a pore volume of 0.043 cm3/***,cyclic voltammetry and electrochemical impedance spectroscopy were used to test the electrochemical properties of the composites,and the stability of BiOCl and the high conductivity of Gp were synergistic,the BiOCl@Gp exhibited a specific capacitance of 30.2 F·g^(-1) at a current density of 0.5 A·g^(-1),and the selectivity of the BiOCl@Gp materials for Cl^(-)was significantly higher than that of SO_(4)^(2-),NO_(2)^(-),and HCO_(3)^(-).Therefore,BiOCl@Gp composite electrode materials can be used for the selective adsorption of Cl^(-)in wastewater,in order to achieve efficient wastewater recycling.

关键词： solvothermal method bismuth oxychloride electrochemistry electrode materials

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Strip flatness prediction of cold rolling based on ensemble methods

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Journal of Iron and Steel Research International 2024年第1期31卷 237-251页

作者： Wu-quan Yang Zhi-ting Zhao Liang-yu Zhu Xun-yang Gao Li Wang School of Mechanical and Power Engineering Shenyang University of Chemical TechnologyShenyang110142LiaoningChina

Aiming at the problem of insufficient prediction accuracy of strip flatness at the outlet of cold tandem rolling,the prediction performance of strip flatness based on different ensemble methods was studied and a high-precision prediction ensemble model of strip flatness at the outlet was ***,based on linear regression(LR),K nearest neighbors(KNN),support vector regression,regression trees(RT),and backpropagation neural network(BPN),bagging,boosting,and stacking ensemble methods were used for ensemble ***,three existing ensemble models,i.e.,random forest,extreme random tree(ET)and extreme gradient boosting,were used to conduct experiments and compare the *** research shows that bagging,boosting,and stacking three ensemble methods have the most significant improvement in the prediction accuracy of the regression trees model,which is increased by 5.28%,6.51%,and 5.32%,*** the same time,the stacking ensemble method improves both the simple model and the complex model,and the improvement effect on the simple base model is the greatest,which is 4.69%higher than that of the base model *** all of the ensemble models,the stacking ensemble model of level-1(ET,AdaBoost-RT,LR,BPN)paired with level-2(LR)was discovered to be the best model(EALB-LR)and can be further studied for industrial applications.

关键词： Tandem cold rolling Flatness prediction Machine learning Ensemble method

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