Efficient desorption and reuse of collector from the flotation concentrate:A case study of scheelite

Flotation is the most common method to obtain concentrate through the selective adsorption of collectors on target minerals to make them hydrophobic and floatable.In the hydrometallurgy of concentrate,collectors adsorbed on concentrate can damage ion-exchange resin and increase the chemical oxygen demand(COD)value of wastewater.In this work,we proposed a new scheme,i.e.,desorbing the collectors from concentrate in ore dressing plant and reusing them in flotation flowsheet.Lead nitrate and benzohydroxamic acid(Pb-BHA)complex is a common collector in scheelite flotation.In this study,different physical(stirring or ultrasonic waves)and chemical(strong acid or alkali environment)methods for facilitating the desorption of Pb-BHA collector from scheelite concentrate were explored.Single-mineral desorption tests showed that under the condition of pulp pH 13 and ultrasonic treatment for 15 min,the highest desorption rates of Pb and BHA from the scheelite concentrate were 90.48%and 63.75%,respectively.Run-of-mine ore flotation tests revealed that the reuse of desorbed Pb and BHA reduced the collector dosage by 30%for BHA and 25%for Pb.The strong alkali environment broke the chemical bonds between Pb and BHA.The cavitation effect of ultrasonic waves effectively reduced the interaction intensity between Pb-BHA collector and scheelite surfaces.This method combining ultrasonic waves and strong alkali environment can effectively desorb the collectors from concentrate and provide“clean”scheelite concentrate for metallurgic plants;the reuse of desorbed collector in flotation flowsheet can reduce reagent cost for ore dressing plants.

Resequencing-based QTL mapping for yield and resistance traits reveals great potential of Oryza longistaminata in rice breeding

As a natural genetic reservoir, wild rice contains many favorable alleles and mutations conferring high yield and resistance to biotic and abiotic stresses. However, there are few reports describing favorable genes or QTL from the AA genome wild rice O. longistaminata, which is characterized by tall and robust habit and long tassels and anthers and shows high potential for use in cultivated rice improvement. We constructed a stable BC_(2)F_(20) backcross inbred line(BIL) population of 152 lines from the cross of 9311 × O.longistaminat. Some BILs showed large panicles, large seeds, and strong resistance to rice false smut, bacterial leaf blight, rice blast spot, and brown planthopper. Genomic resequencing showed that the 152 BILs covered about 99.6% of the O. longistaminata genome. QTL mapping with 2432 bin markers revealed 13QTL associated with seven yield traits and eight with resistance to brown planthopper and to four diseases. Of these QTL, 12 for grain yield and 11 for pest and disease resistance are novel in Oryza species.A large-panicle NIL1880 line containing QTL qPB8.1 showed a nearly 50% increase in spikelet number and27.5% in grain yield compared to the recurrent parent 9311. These findings support the potential value of O. longistaminata for cultivated rice improvement.

Ethylenediamine tetramethylenephosphonic acid as a selective collector for the improved separation of chalcopyrite against pyrite at low alkalinity

Chalcopyrite is the main Cu-containing mineral and cannot be separated well from pyrite using traditional xanthate collectors with large amounts of lime depressant, resulting in difficulties of the tailing treatment and associated precious metals recovery. Therefore, in this study, the green and odourless ethylenediamine tetramethylenephosphonic acid(EDTMPA) was introduced as a novel chalcopyrite collector. Flotation results from the binary mineral mixture and real ore demonstrated that EDTMPA could realize the selective separation of chalcopyrite from pyrite relative to ethyl xanthate(EX) without any depressants within the wide p H range of 6.0–11.0, and might replace the traditional high-alkaline lime process. Electrochemical and Fourier transform infrared spectra measurements indicated that the difference in adsorption performance of EDTMPA on chalcopyrite and pyrite was larger than that of EX, suggesting a better selectivity for EDTMPA. Density functional theory calculations demonstrated that there were stronger chemical bonds between P—O groups of EDTMPA and the Fe/Cu atoms on chalcopyrite in the form of a stable six-membered ring. Crystal chemistry calculations further revealed that the activity of metal atoms of chalcopyrite was higher than that of pyrite. Therefore, these basic theoretical results and practical application provide a guidance for the industrial application of EDTMPA in chalcopyrite flotation.

TiO_(2)@NH_(2)-MIL-125(Ti) composite derived from a partial-etching strategy with enhanced carriers' transfer for the rapid photocatalytic Cr(Ⅵ) reduction

Metal-organic frameworks (MOFs)-based composites have been widely applied as photocatalysts because of their synergistic effect between the two individual component.Herein,TiO_(2)@NH_(2)-MIL-125(Ti) nanocomposites which possess unsaturated titanium–oxo clusters,mesoporous structure,and intimate interface were successfully constructed via an in-situ distilled water-etched route.The X-ray photoelectron spectroscopy (XPS) measurements indicated strong electronic interaction between TiO_(2)and NH_(2)-MIL-125(Ti),confirming the formation of TiO 2@NH_(2)-MIL-125(Ti) nanocomposite.Photoelectrochemical and thermodynamics measurements showed that TiO_(2)@NH_(2)-MIL-125(Ti)nanocomposites have improved charge separation efficient and decreased transfer resistance of the carriers within the heterojunction interfaces,which facilitates the photoexcited electrons transfer and reduction of the Cr(VI) species.Therefore,the optimal TiO_(2)@NH_(2)-MIL-125(Ti)nanocomposite demonstrated superior performance compared to NH_(2)-MIL-125(Ti) and NH_(2)-MIL-125(Ti) derived TiO_(2).Based on the free radical trapping experiment and electron paramagnetic resonance (EPR) measurements,a possible type-II scheme was proposed for the enhanced photocatalytic activity over the TiO_(2)@NH_(2)-MIL-125(Ti) nanocomposite.

Mechanism of calcium lignosulfonate in apatite and dolomite flotation system

Since the physical and chemical properties of apatite and dolomite can be similar,the separation of these two minerals is difficult.Therefore,when performing this separation using the flotation method,it is necessary to search for selective depressants.An experimental research was performed on the separation behavior of apatite and dolomite using calcium lignosulfonate as a depressant,and the mechanism by which this occurs was analyzed.The results show that calcium lignosulfonate has a depressant effect on both apatite and dolomite,but the depressant effect on dolomite is stronger at the same dosage.Mechanism analysis shows that the adsorptive capacity of calcium lignosulfonate on dolomite is higher than that of apatite,which is due to the strong reaction between calcium lignosulfonate and the Ca sites on dolomite.In addition,there is a hydrogen bond between calcium lignosulfonate and dolomite,which further prevents the adsorption of sodium oleate to dolomite,thus greatly inhibiting the flotation of dolomite.

Gas leakage recognition for CO2 geological sequestration based on the time series neural network

The leakage of stored and transported CO2 is a risk for geological sequestration technology. One of the most challenging problems is to recognize and determine CO2 leakage signal in the complex atmosphere background. In this work, a time series model was proposed to forecast the atmospheric CO2 variation and the approximation error of the model was utilized to recognize the leakage. First, the fitting neural network trained with recently past CO2 data was applied to predict the daily atmospheric CO2. Further, the recurrent nonlinear autoregressive with exogenous input(NARX) model was adopted to get more accurate prediction. Compared with fitting neural network, the approximation errors of NARX have a clearer baseline, and the abnormal leakage signal can be seized more easily even in small release cases. Hence, the fitting approximation of time series prediction model is a potential excellent method to capture atmospheric abnormal signal for CO2 storage and transportation technologies.

Particle-in-cell simulation for effect of anode temperature on discharge characteristics of a Hall effect thruster

Propellant gas flow has an important impact on the ionization and acceleration process of Hall effect thrusters （HETs）. In this paper, a particle-in-cell numerical method is used to study the effect of the anode temperature, i.e., the flow speed of the propellant gas, on the discharge characteristics of a HET. The simulation results show that, no matter the magnitude of the discharge voltage, the calculated variation trends of performance parameters with the anode temperature are in good agreement with the experimental ones presented in the literature. Further mechanism analysis indicates that the magnitude of the electron temperature is responsible for the two opposing variation laws found under different discharge voltages. When the discharge voltage is low, the electron temperature is low, and so is the intensity of the propellant ionization; the variation of the thruster performance with the anode temperature is thereby determined by the variation of the neutral density that affects the propellant utilization efficiency. When the discharge voltage is high, the electron temperature is large enough to guarantee a high degree of the propellant utilization no matter the magnitude of the anode temperature. The change of the thruster performance with the anode temperature is thus dominated by the change of the electron temperature and consequently the electron-neutral collisions as well as the electron cross-field mobility that affect the current utilization efficiency.

Prevalence and Genomic Characterization of Multidrug-Resistant Salmonella enterica Serovar Kentucky Sequence Type 198 Circulating—Beijing Municipality,China,2016–2023

Introduction Highly fluoroquinolone-resistant Salmonella enterica serovar Kentucky(S.Kentucky)of sequence type(ST)198 has emerged as a global multidrug-resistant(MDR)clone,posing a threat to public health.Methods Whole genome sequencing and antibiotic susceptibility testing was used to characterize the population structure and evolutionary history of 54 S.Kentucky isolates recovered from food and human clinical cases in Beijing from 2016 to 2023.Results All 54 S.Kentucky ST198 isolates exhibited resistance to quinolones,carrying point mutations in the quinolone resistance-determining regions(gyrA_S83F and parC_S80I).Resistance to other antibiotics(folate pathway inhibitors,cephems,aminoglycosides,phenicols,rifamycin,fosfomycin,macrolides,and tetracyclines),mediated by the sul1,sul2,dfrA14,blaCTX-M,blaTEM-1B,aac(3)-Id,aadA2,aadA7,aph(3')-I,aph(3'')-Ib,rmtB,floR,arr-2,fosA,mph(A),and tet(A)genes,was also observed in different combinations.The Beijing S.Kentucky ST198 evolutionary tree was divided into clades 198.2-1 and 198.2-2,which were further differentiated into three subclades:198.2-2A,198.2-2B,and 198.2-2C.Compared with the extended-spectrumβ-lactamase-encoding gene blaCTX-M-14b in 198.2-1,the co-existence of blaCTX-M-55 and blaTEM-1B,as well as chromosomally located qnrS1,was detected in most 198.2-2 isolates,which showed more complex MDR phenotypes.S.Kentucky ST198 outbreak isolates derived from two predominant clonal sources:198.2-1 with cgST236434 and 198.2-2A with cgST296405.Conclusions The S.Kentucky population in Beijing is genetically diverse,consisting of multiple co-circulating lineages that have persisted since 2016.Strengthening surveillance of food and humans will aid in implementing measures to prevent and control the spread of AMR.

Risk Factors for Norovirus Outbreaks in Schools and Kindergartens—Beijing Municipality,China,July 2017–June 2022

What is already known on this topic?Norovirus is the leading cause of global acute gastroenteritis outbreaks.Norovirus outbreaks mainly occur in schools and kindergartens in China,always causing public health issues.What is added by this report?Conditional logistic regression method was used to analyze the risk factors for norovirus outbreaks in schools and kindergartens,and found that students vomiting at school or kindergarten,case activity in public areas,and the first case’s classroom less than 5 meters from toilets were risk factors.What are the implications for public health practice?Effective measures to address these factors can help reduce the risk of norovirus outbreaks in schools and kindergartens.

Acute gastroenteritis outbreaks caused by human astrovirus,1978-2021:A systematic review

Human astrovirus(HAstV)is one of the main pathogens that cause sporadic cases of acute gastroenteritis,sometimes leading to outbreaks.This study aimed to elucidate the epidemiological and etiological character-istics of HAstV outbreaks worldwide.Literature on HAstV outbreaks published before January 2022 was retrieved from the China National Knowledge Infrastructure,WanFang,WeiPu,PubMed,and Web of Science databases.Date,region,population,settings,transmission modes,clinical symptoms,and etiological characteristics of the outbreaks were collected and analyzed.Thirty-one articles on 32 HAstV outbreaks reported between November 1978 and October 2018 were included.The outbreaks mainly occurred in autumn(14/32,43.75%),and more of them were reported in 1996,2004,and 2017.Outbreaks were primarily dis-tributed in the Northern Hemisphere and mainly occurred in nursery centers and kindergartens(9/29,31.03%),hospitals(5/29,17.24%),and schools(4/29,13.79%).Viral genotypes were identified during 19 outbreaks,and HAstV-1 was predominant(8/19,42.10%).Eleven outbreaks were caused by mixed infection,and norovirus(9/11,81.82%)and rotavirus(5/11,45.45%)were the most common mixed pathogens.The transmission routes were reported in 9 outbreaks of mixed infection,and most(7/9)were related to water-borne and foodborne transmission.Although HAstV outbreaks are infrequently reported,it is necessary to con-sider HAstV in norovirus-negative gastroenteritis outbreaks.In addition,local Centers for Disease Control and Prevention should have the capacity to handle HAstV outbreaks and identify pathogens.

Asymptomatic Norovirus Infection Among Children in Kindergartens and Primary Schools—Beijing Municipality,China,2021

Summary What is already known about this topic?Children in kindergartens and primary schools are the high-incidence groups of norovirus acute gastroenteritis.However,asymptomatic norovirus infection among them is seldom reported.What is added by this report?The norovirus positive rate was 3.48% among asymptomatic children in kindergartens and primary schools in Beijing Municipality in June 2021,the most common genotype was GII.4 Sydney,and no acute gastroenteritis outbreak was reported over the study period.

Octagold selenido nanoclusters:Significance of surface ligands on tuning geometric and electronic structure of Au8Se2 kernel

Two diphosphine-protected superatom gold selenido nanoclusters,[Au_(8)Se_(2)(dppm)4]^(2+)(SD/Au_(8)a,dppm=Ph_(2)PCH_(2)PPh_(2))and[Au_(8)Se_(2)(dppe)4]^(2+)(SD/Au_(8)b,dppe=Ph_(2)P(CH_(2))2PPh_(2)),were obtained by the reduction of[Au(SMe2)Cl]in the presence of Ph3PSe as the selenium ion releasing agents.Both can be regarded as“superatoms”with 1S^(2)configuration based on the spherical Jellium model.Despite the same metal-ligand binding motifs on the surface and the intrinsic C_(2)molecular symmetry,the configurations of Au_(8)Se_(2)kernels in them are different in terms of Au-Au bonded metallic frameworks.SD/Au_(8)a displays a heart-shaped[core+exo]type structure(Au4 tetrahedron core+two exo Au2Se units),whereas the two exo Au_(2)Se counterparts in SD/Au_(8)b are additionally locked by an obvious Au-Au bond,forming a distorted hexagonal Au6 ring with two capping AuSe units appended above and below it.Consequently,they showed different photophysical properties as reflected by their electronic absorption and emission spectra.Especially,both SD/Au_(8)a and SD/Au_(8)b exhibit blue-shifted thermochromic luminescence upon cooling from 293 to 83 K but the latter exhibits anomalous emission intensity evolution trends due to the occurrence of temperature-induced phase transition as revealed by varied-temperature crystallographic analyses.This work not only clearly illustrates the significance of ligands on tuning the kernel structure but also provides two rarely comparable examples for better understanding of the structure-property relationship of gold nanoclusters.

Microstructure evolution and superelasticity behavior of Ti-Ni-Hf shape memory alloy composite with multi-scale and heterogeneous reinforcements

In the present study,the in-situ TiB whisker was introduced into the Ti-Ni-Hf shape memory alloy composite by the in-situ reaction of the Ti-Ni-Hf alloy powder and TiB2 powders.The(Ti,Hf)2 Ni phase also precipitated,accompanied with the formation of TiB phase.Moreover,the residual TiB2 particles can be observed,as the TiB2 content was higher than 0.7 wt%.Thereinto,the larger scale reinforcements constituted the quasi-continuous network structure.The smaller scale reinforcements distributed in the interior of the network structure.The two-scale reinforcements showed the uniform distribution at macroscopic level and inhomogeneous distribution at microscopic level.The single stage B19?B2 martensitic transformation occurred in the Ti-Ni-Hf composites.In addition,the martensitic transformation temperatures continuously decreased with the increased TiB2 content owing to the compositional and mechanical effect.The moderate TiB2 addition not noly enhanced the matrix strength,but also significantly improved the superelasticity.The excellent superelaticity with the completely recoverable strain of 4%can be obtained in the Ti-Ni-Hf composite containing 0.7 wt%TiB2.

Optimization design of fertilizer apparatus owned arc gears based on discrete element method

To improve the uniformity of the flow when fertilizer apparatus discharges fertilizer,a kind of fertilizer apparatus owned arc gears was designed.Also,the design and working principle of its general structure and key components were analyzed theoretically.Aiming at exploring the influence of arc structural parameters to the performance of arc gears discharging fertilizer,DEM simulation was used in this study.Fertilizer apparatus owned arc gears was taken as the research object to analyze the influence of two key components including the arc radius of gears’concave-grooves and the minimal length between two mutual meshing gears.The variation coefficient of fertilizer discharging amount stability and the linear determined coefficient of fertilizer discharging amount in unit time as evaluation index were selected.Two factors and five levels quadratic rotation orthogonal experiment was applied,and Design-Expert 8.0 software was used to achieve data processing and analysis.The results of experiment indicated that the arc radius of gears’concave-grooves had significant effect on the linear determined coefficient of fertilizer discharging amount in unit time,and the minimal length between two mutual meshing gears had significant effect on the variation coefficient of fertilizer discharging amount stability.The optimum structural parameters were 8.54 mm as the arc radius of gears’concave-grooves and 5.22 mm as the minimal length between two mutual meshing gears.Upon this circumstance,the variation coefficient was 0.28 and determination coefficient was 0.9972.The optimum apparatus was selected to conduct the bench test and field simulation test.The results indicated that the variation coefficient is 0.27,and the linear determined coefficient of is 0.9980.The results of simulation experiment were anastomotic basically with the real result,which showed that DEM simulation technology was usable to the experiment of testing fertilizer discharging.The results of this research can provide a reference to the improving of performance in discharging fertilizer.

Model construction of soybean average diameter and hole parameters of seed-metering wheel based on DEM

To satisfy the demands of soybean precision sowing,this article starts with statistics of the physical parameters of soybean seeds in Heilongjiang province,China.The filling process of soybean seeds was analyzed,and the ratio relationship between the diameter,depth,chamfer length of seed-metering wheel’s holes and the mean diameter of soybean seeds was determined.EDEM was used to simulate seeding circumstances of hole seed-metering wheel with different holes’sizes.The hole diameter ratio,hole depth ratio,and chamfer length ratio were the test factors,while the percentage of single multiple and the empty seeds were test indexes.The triple quadratic regression orthogonal rotation combination test was designed,and the mathematical model between test indexes and test factors was established.Results showed that the influence of hole diameter ratio and hole depth ratio was significant(p<0.01)in the case of single,multiple and empty seed percentage while chamfer length ratio was only significant in single seed percentage compared to multiple and empty seeds percentage(p>0.05).The chamfer length ratio was 0.15,the hole diameter ratio was 1.63-1.73,the hole depth ratio was 0.81-1.20,the quality of seeding index was more than 90,and multiple and missing indexes were less than 6%and 4%,respectively.The soybean hole wheel seeding device was produced under the optimal parameter combination,to perform a comparative verification test with non-optimized parameters.The test showed anastomotic simulation results,verified the validity of the simulation.The seeding device after optimization expressed the best operating performance,which might satisfy the demands of soybean precision sowing.The study results can provide a theoretical reference for the optimization design of soybean seeding devices.

Extensively Drug-Resistant(XDR)Salmonella Typhi Outbreak by Waterborne Infection——Beijing Municipality,China,January-February 2022

Summary What is already known about this topic?Typhoid fever remains a major public health problem in developing countries.Waterborne typhoid fever affects an estimated 27 million people worldwide each year.Decades of indiscriminate antibiotic usage has driven the emergence and spread of multidrug-resistant(MDR)and even extensively drug-resistant(XDR)Salmonella Typhi(S.Typhi)strains.

Generation of the genetic mutant population for the screening and characterization of the mutants in response to drought in maize

The autonomous Mutator(Mu)transposon in maize(Zea mays L.)lines 115F,330I,and 715D were crossed with inbred lines B73,Mo17,97108,and H9-21,M1were self-pollinated to establish the Mu insertion-mutagenized M2seeds pool and The M2plants encompassed a large amount of biological variation relevant to improving agronomy traits by observed in the field.Next we statistically analyzed these candidate mutants.Under drought stress,we screened seedlings at 3-leaf stage by using the infrared thermography,and successfully got 108 droughtinsensitive and 121 drought-sensitive candidate mutants from more than 38,000 lines,which temperature were significant different with others.These candidate mutants were primarily analyzed by infrared thermography,chlorophyll fluorescence,leaf water losing,photosynthetic characteristics,content of soluble sugars,soluble protein,and proline assay.The selected mutants were cloned by MuTAIL–PCR methods.Here we provide the better genetic materials for research on maize breeding for drought tolerance.

Cholera Caused by a New Clone of Serogroup O1 Vibrio cholerae-Beijing Municipality,China,June 2021

Several lineages have been identified in the population of serogroup O1 Vibrio cholerae(V.cholerae)(1-3).The strains,which were responsible for the ongoing seventh cholera pandemic,were in Lineage 2.Nearly all the V.cholerae strains in this lineage carried genes coding cholera toxin(ctxAB)(1-2).Lineage 3b consists of strains isolated from different continents and the vast majority of strains in this lineage lack the ctxAB genes.

Revealing the interface structure of{111}typeⅠtwin in Ti-Ni-Hf shape memory alloy composite

1.Introduction Ti-Ni-Hf high temperature shape memory alloys have attracted great interests of many researchers due to the higher transformation temperatures and relatively lower cost[1,2].However,the recoverable strain is about 3%,which is signifcantly lower than the theoretical value[3-5].The functional performances of shape memory alloys are closely related to the substructure of twinned martensite and the structure of intervariant interface.

Tailoring the microstructure,martensitic transformation and strain recovery characteristics of Ti-Ta shape memory alloys by changing Hf content

In the present work,the microstructure features,martensitic transformation,mechanical properties and strain recovery characteristics of Ti-Ta based shape memory alloys were tailored by changing Hf contents.The singleα"martensite phase was dominated in Ti-Ta alloy with 2 at.%H f.Upon Hf content exceeded2 at.%,βphase started to appear.Moreover,the amount ofβphase gradually increased with Hf content increasing.The martensitic transformation temperatures continuously decreased with the increased Hf content,which was attributed to the rising of valence electron concentration.Meanwhile,Hf addition improved the thermal cycling stability of Ti-Ta alloys due to the suppression ofωprecipitation.The yield stress of Ti-Ta based alloys firstly decreased and then increased with Hf content increasing.In addition,the completely recoverable strain of 4%can be obtained in Ti-Ta alloy with 6 at.%Hf as a consequence of the higher critical stress for dislocation slip.Besieds,the Ti-Ta based alloy containing 8 at.%Hf had the superior superelasticity behavior with the fully recoverable strain of 2%at room temperature.