An integrated and efficient process for borax preparation and magnetite recovery from soda-ash roasted ludwigite ore under CO–CO_(2)–N_(2) atmosphere

To realize the comprehensive utilization of ludwigite ore,an integrated and efficient route for the boron and iron separation was proposed in this work,which via soda-ash roasting under CO–CO_(2)–N_(2) atmosphere followed by grind-leaching,magnetic separation,and CO_(2) carbonation.The effects of roasting temperature,roasting time,CO/(CO+CO_(2))composition,and Na_(2)CO_(3) dosage on the boron and iron separation indices were primarily investigated.Under the optimized conditions of the roasting temperature of 850℃,roasting time of 60 min,soda ash dosage of 20 wt%,and CO/(CO+CO_(2)) of 10 vol%,92%of boron was leached during wet grinding,and 88.6%of iron was recovered during the magnetic separation and magnetic concentrate with a total iron content of 61.51 wt%.Raman spectra and^(11)B NMR results indicated that boron exists asB(OH)_(4)^(-) in the leachate,from which high-purity borax pentahydrate could be prepared by CO_(2) carbonation.

Life cycle assessment of HFC-134a production by calcium carbide acetylene route in China

HFC-134a is a widely used environment-friendly refrigerant.At present,China is the largest producer of HFC-134a in the world.The production of HFC-134a in China mainly adopts the calcium carbide acetylene route.However,the production route has high resource and energy consumption and large waste emission,and few of the studies addressed on the environmental performance of its production process.This study quantified the environmental performance of HFC-134a production by calcium carbide route via carrying out a life cycle assessment(LCA)using the CML 2001 method.And uncertainty analysis by Monte-Carlo simulation was also carried out.The results showed that electricity had the most impact on the environment,followed by steam,hydrogen fluoride and chlorine,and the impact of direct CO_(2) emissions in calcium carbide production stage on the global warming effect also could not be ignored.Therefore,the clean energy(e.g.,wind,solar,biomass,and natural gas)was used to replace coal-based electricity and coal-fired steam in this study,showing considerable environmental benefits.At the same time,the use of advanced production technologies could also improve environmental benefits,and the environmental impact of the global warming category could be reduced by 4.1%via using CO_(2) capture and purification technology.The Chinese database of HFC-134a production established in this study provides convenience for the relevant study of scholars.For the production of HFC-134a,this study helps to better identify the specific environmental hotspots and proposes useful ways to improve the environmental benefits.

Morphological and phylogenetical analysis reveals that a new tapeworm species (Cestoda: Hymenolepididae) from whooper swan belongs to Cloacotaenia not Hymenolepis

During a helminthological study of waterfowl in China,a new species(Cloacotaenia cygnimorbus sp.nov.)of hymenolepidid cestodes(tapeworm)was found in the small intestine of whooper swan(Cygnus cygnus,Linnaeus,1758).The rudimentary rostellum and four unarmed muscular suckers,proglottids with distinct craspedote and three spherical testes were coincident with the characters of Cloacotaenia or Hymenolepis,but phylogenetic analysis of 28S rRNA and cox1 gene revealed that the new species is Cloacotaenia rather than Hymenolepis.Its morphology was also clearly diff erentiated from C.megalops in the arrangement of its testes in a triangle instead of in line and the cirrus unarmed rather than spined.Compared with C.megalops,the new species has more elongated neck,much larger mature proglottids and much smaller testes,cirrus sac,ovary,vitellarium and uterine proglottid.In addition,it infected the host intestine not the cloacae.Phylogenetic analysis of cox1 gene of the new species shows that it had a level of sequence variation(10.52–23.06%)with the sequences of C.megalops.The considerable morphological and molecular diff erences between those two parasites support C.cygnimorbus sp.nov.as a new species.

The effect of hydrothermal pretreatment on the structure and fast pyrolysis behaviors of Sheng Li lignite

The structure and composition of coal determine its fast pyrolysis characteristics,and the study of the relationship between them can play an important role in the efficient and clean utilization of coal.So,in this work,hydrothermal pretreatment was used to artificially change the structure and composition of Sheng Li(SL)lignite,which was used to investigate the influence of structural changes on pyrolysis.The physicochemical structure and composition of samples were characterized by X-ray diffraction,specific surface area and porosity analyzer,solid-state 13C nuclear magnetic resonance,Fourier transform infrared spectroscopy,and elemental analyzer.Pyrolysis experiments were carried out in a powderparticle fluidized bed reactor,and the distribution and composition of the pyrolysis products were analyzed.The gasification activity of char was investigated by thermogravimetric analysis with a CO_(2) atmosphere.The results show that hydrothermal pretreatment(HTP)can destroy the cross-linking structure of SL lignite,and affect its aromaticity,pore structure,functional group,and carbon structure to change the distribution and composition of pyrolysis products of SL lignite,especially the composition of tar.Finally,the structure–activity relationship between the structure,composition,and pyrolysis characteristics of coal was comprehensively studied.

Correction to:Morphological and phylogenetical analysis reveals that a new tapeworm species(Cestoda:Hymenolepididae)from whooper swan belongs to Cloacotaenia not Hymenolepis

Correction to:J.For.Res.(2020)31(6):2581-2587 https://doi.org/10.1007/s11676-019-01036-2 After publication of this article,it was brought to our atten-tion that the legend to Figure 1 did not state that Figure 1d was adapted from Figure 1d of Makarikov and Tkach(2013).In addition,Makarikov and Tkach(2013)should have been cited in the methods section.

Mineralogical Characterization of Kuru Cassiterite Ore by SEM-EDS,XRD and ICP Techniques

The morphology and elemental characteristics of Kuru Cassiterite ore deposit was performed by the combination of different instruments. This is vital to obtain accurate mineralogical, surface properties and compositions of the ore. Mineral particles were prepared on epoxy resin, polished and analyzed by a SEM coupled with an EDS. X- ray diffraction showed that the ore contained different minerals of cassiterite, coffinite, siderophyllite,ilmenite, qartz, rutile, manganocolumbite, zircon, tilleyite and monazite. Further quantitative analysis using inductive coupled plasma – optical emission spectrometry gave the elemental analysis as follows;Sn (28.0%), Si (5.5%), Fe (5.16%),Ti (3.51%), Al (2.48%), Y (1.06%), and Nb (2.53%). The other trace elements found include Mn, K, Na, Mg, La, Ce, U and Ca. The ICP-OES data was correlated with the XRD data obtained using the Guassian Pro 8.1 origin software and it showed significant correlation.

具有优越镍-锌电池性能的低结晶镍钴氢氧化物

因具有大量的晶界和离子扩散通道,低结晶度的电极活性材料有望在储能领域中实现更好的性能.然而在大多数应用中通常是结晶良好的样品具有更好的稳定性,稳定性较差限制了低结晶样品在相关研究领域的应用.本文利用一种溶剂热法调控N-甲基吡咯烷酮和水混合溶剂的体积比以合成低结晶度的镍钴氢氧化物(NiCo-OH-L).研究发现,将合成的镍钴氢氧化物用作镍-锌电池正极时,NiCo-OH-L不仅表现出与高结晶度的同类样品相当的循环稳定性能,而且在1-50 A g^(-1)的电流范围内显示出更高的容量以及容量保持率.其优异的电化学性能可归因于低结晶的结构,显著提高的比表面积和降低的电荷转移电阻.此外,NiCo-OH-L的钴组分进一步提高了倍率和循环稳定性能.NiCo-OH-L在1 A g^(-1)时的比容量达到238.9 mA h g^(-1),当电流密度升至50 A g^(-1)时的容量仍有116.4 mA h g^(-1),显示出高容量和高倍率性能.不仅如此,由NiCo-OH-L组装成的镍-锌电池在不同的电流和循环周期下也表现出较高的性能.

Preparation of carbon-coated iron oxide nanoparticles dispersed on graphene sheets and applications as advanced anode materials for lithium-ion batteries

We report a novel chemical vapor deposition （CVD） based strategy to synthesize carbon-coated Fe203 nanoparticles dispersed on graphene sheets （Fe2Og@C@G）. Graphene sheets with high surface area and aspect ratio are chosen as space restrictor to prevent the sintering and aggregation of nanoparticles during high temperature treatments （800 ℃）. In the resulting nanocomposite, each individual Fe2O3 nanoparticle （5 to 20 nm in diameter） is uniformly coated with a continuous and thin （two to five layers） graphitic carbon shell. Further, the core-shell nanoparticles are evenly distributed on graphene sheets. When used as anode materials for lithium ion batteries, the conductive-additive-free Fe2OB@C@G electrode shows outstanding Li＋ storage properties with large reversible specific capacity （864 mAh/g after 100 cycles）, excellent cyclic stability （120% retention after 100 cycles at 100 mA/g）, high Coulombic efficiency （-99%）, and good rate capability.

Strain engineering of 2D semiconductors and graphene:from strain fields to band-structure tuning and photonic applications

Two-dimensional(2D)transition metal dichalcogenides(TMDCs)and graphene compose a new family of crystalline materials with atomic thicknesses and exotic mechanical,electronic,and optical properties.Due to their inherent exceptional mechanical flexibility and strength,these 2D materials provide an ideal platform for strain engineering,enabling versatile modulation and significant enhancement of their optical properties.For instance,recent theoretical and experimental investigations have demonstrated flexible control over their electronic states via application of external strains,such as uniaxial strain and biaxial strain.Meanwhile,many nondestructive optical measurement methods,typically including absorption,reflectance,photoluminescence,and Raman spectroscopies,can be readily exploited to quantitatively determine strain-engineered optical properties.This review begins with an introduction to the macroscopic theory of crystal elasticity and microscopic effective low-energy Hamiltonians coupled with strain fields,and then summarizes recent advances in strain-induced optical responses of 2D TMDCs and graphene,followed by the strain engineering techniques.It concludes with exciting applications associated with strained 2D materials,discussions on existing open questions,and an outlook on this intriguing emerging field.

Sandwich structured graphene-wrapped FeS-graphene nanoribbons with improved cycling stability for lithium ion batteries

Sandwich structured graphene-wrapped FeS-graphene nanoribbons （G@FeS-GNIKs） were developed. In this composite, FeS nanoparticles were sandwiched between graphene and graphene nanoribbons. When used as anodes in lithium ion batteries （L1Bs）, the G@FeS-GNR composite demonstrated an outstanding electrochemical performance. This composite showed high reversible capacity, good rate performance, and enhanced cycling stability owing to the synergy between the electrically conductive graphene, graphene nanoribbons, and FeS. The design concept developed here opens up a new avenue for constructing anodes with improved electrochemical stability for LIBs.

Electromagnetic wave absorption properties of cobalt-zinc ferrite nanoparticles doped with rare earth elements

Traditional ferrites are of poor electromagnetic wave(EMW) absorption while doping rare earth elements(REEs) can greatly enhance their permeability to improve the EMW loss performance.In this study,Co-Zn ferrite nanoparticles doped with various amounts of REEs(Gd^(3+),Nd^(3+)and Pr^(3+)) were synthesized by a hydrothermal method,and their particle morphology and an EMW absorption performance were characterized by using transmission electron microscopy(TEM) and a Vector network analyzer(VNA).The results show that the initial spherical Co-Zn ferrite nanoparticles present an irregular quadrilateral structure after Gd^(3+)doping,and the average particle size of Co_(0.5)Zn_(0.5-x)Gd_(x)Fe_(2) O_(4) increases from 26 to 50 nm with x increasing from 0 to 0.35.At x of 0.25,the reflectivity absorbance achieves-27.94 dB at 18 GHz with the effective absorption bandwidth(EAB) of 4.08 GHz at a sample thickness of 2.5 mm.When Nd^(3+)doping amount reaches x=0.3,the minimum reflection loss(RL)is-25.63 dB at 18 GHz and EAB is 3.91 GHz.Doping Pr^(3+)(x=0.25) in the sample broadens EAB,and the minimum RL is-16.1 dB at 16.81 GHz and EAB is 7.31 GHz.This study shows that the magnetic moment produced by doping REES can form magnetic domains,which affects the incident EMW and improves the magnetic loss.It is expected that REEs-doped Co-Zn ferrite nanoparticles can be used as efficient electromagnetic shielding materials in aerospace.

螺二芴和均三嗪构筑的主体材料的合成及应用

设计并合成了4种基于螺二芴和均三嗪类的新型主体材料2-(2′,7′-二叔丁基-9,9′-螺二芴-2-基)-4,6-二苯基-1,3,5-三嗪(DTSF-2-DP-TRZ)、2-(9,9′-螺二芴-2-基)-4,6-双(3,5-二-叔丁基苯基)-1,3,5-三嗪(SF-2-DTDP-TRZ)、2-(9,9′-螺二芴]-4-基)-4,6-双(3,5-二-叔丁基苯基)-1,3,5-三嗪(SF-4-DTDP-TRZ)、2-(9,9′-螺二芴-4-基)-4,6-双(4-(叔丁基)苯基)-1,3,5-三嗪(SF-4-TDP-TRZ),并对其结构和性能进行了表征.利用热重分析、差热分析、紫外可见吸收、荧光、低温磷光、循环伏安法对其物理和化学性质进行了研究,结果表明4种主体材料的热稳定性能优异,紫外-可见光吸收峰位于280～355nm之间;光学带隙(Eg)分布在3.28～3.36eV之间.为了研究其在有机电致发光中的应用,4个主体材料分别与绿光热激活延迟荧光材料共掺作为发光层,通过旋涂法制备,并研究其结构与性能之间的关联.所制备的器件光电性能表现优异,其中DTSF-2-DP-TRZ作为主体材料的器件最大亮度达到6600cd/m^2,最大电流效率为51.3cd/A,相应的最大外量子效率为16.6%.

Global gaps in age data based on skeletochronology for amphibians

Individual age and population age composition are the major concerns of ecologists,evolutionary biologists and conservation biologists.In amphibians,skeletochronology-counting the number of lines of arrested growth deposited in the bone tissue,is the dominant method to determine actual age of an individual.Since 1970s,age data of the ectothermic taxa have been accumulated and increasingly used in comparative studies.Here we make a global assessment for the availability of the data,based on a collection of 369 published papers.For a specific species,more males than females were sampled.Among the extant 8146 amphibian species,only 266(3.3%)have been skeletochronologically investigated.Of these studied species,2(0.9%of 214)belong to caecilians,56(7.6%of 740)salamanders and 208(2.9%of 7192)anurans.A complete paucity of data was seen in 80%,50%,and 54%of families in the corresponding orders.More temperate species than tropical species were sampled,while the proportion of Palearctic species studied was higher than that in the other 5 biogeographical realms.Species inhabiting semi-aquatic niche were more likely to be studied than fossorial or plant dwellers.Age information of multiple populations(2-48)was available for species with a broad distribution,accounts for 61%of salamander and 43%of anuran species studied.Because these gaps in demographic knowledge can limit our understanding of questions ranging from life history evolution,population dynamics to conservation,we encourage herpetologists to pay more efforts on filling them.

An initial coprological survey of parasitic fauna in the wild Amur leopard(Panthera pardus orientalis)

The Amur leopard,one of nine recently recognized subspecies of leopard,is still the most threatened by a stochastic procession of extinction.Evaluation of the potential danger to the conservation of the Amur leopard originating from disease urgently needs to be studied.Unfortunately,research on the potential risk to Amur leopards caused by disease is rare.In terms of parasitic diseases that affect this species,even basic data for parasitic fauna are absent.The aim of this study is to acquire this knowledge to improve the general understanding of Amur leopard parasites.Seven parasite species,including 3 nematodes(Toxocara cati,a capillarid-type parasite,and a Metastrongyloideatype parasite),2 cestodes(Spirometra sp.and Taenia sp.),1 trematode(Paragonimus sp.),and 1 protozoan(Cystoisospora felis),were found in this research.Toxocara cati occurred most frequently,followed by Spirometra sp.