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Direct microwave leaching conditions of rare earth elements in fluorescent wastes

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Journal of Rare Earths 2024年第6期42卷 1165-1174,I0007页

作者： A.bilen b.birol M.N.Saridede S.S.Kaplan M.S.Sonmez Department of Metallurgical and Materials Engineering Yildiz Technical UniversityIstanbulTurkey Department of Chemical Engineering and Materials Science Stevens Institute of TechnologyNew JereyUSA Department of Metallurgical and Materials Engineering Istanbul Technical UniversityIstanbulTurkey

The luminescent phosphor powder in the fluorescent lamp constitutes 2%of the lamp’s *** can be mentioned that fluorescent wastes are a crucial raw material to produce rare earth *** the present study,microwave leaching process was conducted to dissolve rare earth elements yttrium(Y),europium(Eu),and remaining rare earth elements(REEs)present in the phosphor powder of the fluorescent *** the yields were *** the microwave leaching process,the effects of the temperature(80-160℃),acid type(hydrochloric acid(HCl),nitric acid(HNO_(3)),sulphuric acid(H_(2)SO_(4))),acid concentration(0.5-6 mol/L),solid to liquid ratio(0.1:10-0.5:10)and reaction time(5-90 min)parameters on leaching efficiencies of varying rare earth elements and calcium were *** highest yield was obtained in the direct microwave leaching of fluorescent waste with the experimental conditions of 6 mol/L HCl,160℃,0.1:10 solid-to-liquid ratio(S:L),and 90 *** energy calculations were made,and kinetic models of the reactions were obtained,and it is observed that Y and Eu dissolution is diffusion-controlled,on the other hand,lanthanum(La),cerium(Ce),and terbium(Tb)were examined to be chemical reaction ***,calcium(Ca)and gadolinium(Gd)seem coherent with the mixed ***,mathematical models of all experimental studies are created with the response surface box-behnken method and the correlation coefficients of all the models are over 90%.

关键词： Rare earth elements(REEs) Direct microwave leaching Fluorescent waste Kinetic models Response surface method

Rare earth-doped mixed Ni-Cu-Zn ferrites as an effective photocatalytic agent for active degradation of Rhodamine b dye

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Journal of Rare Earths 2024年第3期42卷 488-496,I0003页

作者： Swapnil A.Jadhav Sandeep b.Somvanshi Sudarshan S.Gawali Kranti Zakde K.M.Jadhav Department of Physics Dr.Babasaheb Ambedkar Marathwada UniversityAurangabad431004MaharashtraIndia School of Materials Engineering Purdue UniversityWest Lafayette 47906USA University Department of basic and Applied Sciences MGM UniversityAurangabad431003MaharashtraIndia

In this study, a series of Gd^(3+)-doped mixed Ni-Cu-Zn ferrites with composition of Zn_(0.5)Ni_(0.3)Cu_(0.2)Fe_(2-x)Gd_(x)O_(4)(x = 0, 0.025, 0.05, 0.075, 0.1) was prepared using self-ignition sol-gel method. The prepared nanoparticles with an average size ranging from 22 to 26 nm show a single-phase cubic structure belonging to the spinel matrix. A rise in the Gd^(3+)concentration leads to an increase in crystallite size and lattice parameter. In Fourier transform infrared spectra, two main absorption bands belonging to the spinel structure are observed. The high-frequency bands(v_(1)) represent the tetrahedral complex, while the lowfrequency bands(v_(2)) signify the octahedral complex. The optical bandgap of the nanoferrites is found within the range of 2.91 to 2.41 eV, depending on their size. The magnetic characteristics of the material,such as saturation magnetization and coercivity are significantly altered with the concentration of Gd^(3+)in the solution. Using Rhodamine b(Rhb) as a model organic pollutant, an in-depth investigation of the photocatalytic activity of the compounds was carried out. The present outcomes show that adding an adequate amount of Gd^(3+)significantly enhances the number of hydroxyl radicals produced by the ferrite,in turn, increasing the photocatalytic activity of the material. Mechanism elucidated by scavenger studies reveals that ·OH and holes are the primary reactive radicals responsible for the degradation *** photocatalysts show an insignificant performance loss in five consecutive cycles. Thus, it is concluded that these photocatalysts are highly suitable for the remediation of dye-contaminated wastewater.

关键词： Gd^(3+)substitution Spinel ferrite Structural properties Magnetic properties Photocatalysis Rare earths

Three- and Four-Dimensional Generalized Pythagorean Numbers

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Advances in Pure Mathematics 2024年第1期14卷 1-15页

作者： Alfred wünsche Institute of Physics Humboldt University Berlin Germany

The Pythagorean triples (a, b | c) of planar geometry which satisfy the equation a2+b2=c2 with integers (a, b, c) are generalized to 3D-Pythagorean quadruples (a, b, c | d) of spatial geometry which satisfy the equation a2+b2+c2=d2 with integers (a, b, c, d). Rules for a parametrization of the numbers (a, b, c, d) are derived and a list of all possible nonequivalent cases without common divisors up to d2 is established. The 3D-Pythagorean quadruples are then generalized to 4D-Pythagorean quintuples (a, b, c, d | e) which satisfy the equation a2+b2+c2+d2=e2 and a parametrization is derived. Relations to the 4-square identity are discussed which leads also to the N-dimensional case. The initial 3D- and 4D-Pythagorean numbers are explicitly calculated up to d2, respectively, e2.

关键词： Number Theory Pythagorean Triples Tesseract 4-Square Identity Diophantine Equation

Convergence Phenomenon with Fourier Series of tg(x2)and Alike

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Advances in Pure Mathematics 2024年第7期14卷 556-595页

作者： Alfred wünsche Institut fr Physik Humboldt-Universitt Berlin Berlin Germany

The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generalized functions and the convergence is weak convergence in the sense of the convergence of continuous linear functionals defining them. The figures show that the approximations of the Fourier series possess oscillations around the function which they represent in a broad band embedding them. This is some analogue to the Gibbs phenomenon. A modification of Fourier series by expansion in powers cosn(x)for the symmetric part of functions and sin(x)cosn−1(x)for the antisymmetric part (analogous to Taylor series) is discussed and illustrated by examples. The Fourier series and their convergence behavior are illustrated also for some 2π-periodic delta-function-like sequences connected with the Poisson theorem showing non-vanishing oscillations around the singularities similar to the Gibbs phenomenon in the neighborhood of discontinuities of functions. .

关键词： Gibbs Phenomenon Generalized Functions weak Convergence Chebyshev Polynomials of First and Second Kind Even and Odd Generating Functions for Chebyshev Polynomials Polylogarithms Completeness Relations

what diameter?what height?Influence of measures of average tree size on area-based allometric volume relationships

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Forest Ecosystems 2024年第1期11卷 100-109页

作者： Yilin wang John A.Kershaw Mark J.Ducey Yuan Sun James b.McCarter Integrated Forest Mensuration and Systems Analysis Laboratory Faculty of Forestry and Environmental ManagementUniversity of New BrunswickFrederictonNBCanada Department of Natural Resources and the Environment University of New HampshireDurhamNHUSA College of Forestry Nanjing Forestry UniversityNanjing210037China Scientific Programmer RayonierYuleeFLUSA

Volume is an important attribute used in many forest management *** from 83 fixed-area plots located in central New brunswick,Canada,are used to examine how different measures of stand-level diameter and height influence volume prediction using a stand-level variant of Honer's(1967)volume *** density was included in the models(Volume=f(Diameter,Height,Density))choice of diameter measure was more important than choice of height *** density was not included(Volume=f(Diameter,Height)),the opposite was *** models with density included,moment-based estimators of stand diameter and height performed better than all other *** models without density,largest tree estimators of stand diameter and height performed better than other *** overall best equation used quadratic mean diameter,Lorey's height,and density(root mean square error=5.26 m^3·ha^(-1);1.9%relative error).The best equation without density used mean diameter of the largest trees needed to calculate a stand density index of 400 and the mean height of the tallest 400 trees per ha(root mean square error=32.08 m^(3)·ha^(-1);11.8%relative error).The results of this study have some important implications for height subsampling and LiDAR-derived forest inventory analyses.

关键词： Allometric relationships Stand structure Volume estimation Stand-level attributes

Decellularised extracellular matrix-based injectable hydrogels for tissue engineering applications

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biomaterials Translational 2024年第2期5卷 114-128页

作者： Guo w.-Y. wang w.-H. Xu P.-Y. Kankala R.K. Chen A.-Z. Institute of biomaterials and Tissue Engineering Huaqiao University Fujian Province Xiamen China Fujian Provincial Key Laboratory of biochemical Technology (Huaqiao University) Fujian Province Xiamen China

Decellularised extracellular matrix (dECM) is a biomaterial derived from natural tissues that has attracted considerable attention from tissue engineering researchers due to its exceptional biocompatibility and malleability attributes. These advantageous properties often facilitate natural cell infiltration and tissue reconstruction for regenerative medicine. Due to their excellent fluidity, the injectable hydrogels can be administered in a liquid state and subsequently formed into a gel state in vivo, stabilising the target area and serving in a variety of ways, such as support, repair, and drug release functions. Thus, dECM-based injectable hydrogels have broad prospects for application in complex organ structures and various tissue injury models. This review focuses on exploring research advances in dECM-based injectable hydrogels, primarily focusing on the applications and prospects of dECM hydrogels in tissue engineering. Initially, the recent developments of the dECM-based injectable hydrogels are explained, summarising the different preparation methods with the evaluation of injectable hydrogel properties. Furthermore, some specific examples of the applicability of dECM-based injectable hydrogels are presented. Finally, we summarise the article with interesting prospects and challenges of dECM-based injectable hydrogels, providing insights into the development of these composites in tissue engineering and regenerative medicine. © 2024, Chinese Medical Multimedia Press Co Ltd. All rights reserved.

关键词： decellularisation methods decellularised extracellular matrix injectable hydrogels tissue engineering

Precipitation of multi-type nano-quasicrystals in a Mg-Zn-Y alloy

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Journal of Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： w.Z.wang X.Z.Zhou L.F.Zhang H.Q.Ye Z.Q.Yang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China Ji Hua Laboratory Foshan 528251China Foshan University Foshan 528231China

Mg-6Zn-1Y(at.%)ribbons with strengthening precipitates of multi-type nanoquasicrystals were prepared by melt-spinning followed by aging *** evolution of the rapidly solidified ribbons during isothermal aging was comprehensively studied using various electron microscopy *** new kinds of decagonal quasicrystals were formed in aged ribbons,in addition to precipitation of nanometer icosahedral ***-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling with decagonal clusters of 2.5 nm in diameter,but overlap of neighboring clusters in both decagonal quasicrystals is different from the Gummelt model observed in other quasicrystals.A shell composed of complex Laves Mg-Zn domains was formed surrounding each decagonal quasicrystal precipitate upon prolonged *** addition,all kinds of nanoprecipitates exhibit excellent structure and size stability at 573 *** findings may have implications for not only fundamental studies about quasicrystals,but also microstructural manipulation of high-performance Mg alloys.

关键词： Quasicrystal Mg alloys Rapid solidification Scanning-transmission electron microscopy.

Interfacial stress engineering toward enhancement of ferroelectricity in Al doped HfO_(2)thin films

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Chinese Physics b 2024年第9期33卷 637-643页

作者： S X Chen M M Chen Y Liu D w Cao G J Chen Department of Microelectronics Jiangsu UniversityZhenjiang 212013China Department of Physics Jiangsu UniversityZhenjiang 212013China Guangdong–Hong Kong–Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology Foshan UniversityFoshan 528225China

Ferroelectric HfO_(2)has attracted much attention owing to its superior ferroelectricity at an ultra-thin thickness and good compatibility with Si-based complementary metal-oxide-semiconductor(CMOS)***,the crystallization of polar orthorhombic phase(o-phase)HfO_(2)is less competitive,which greatly limits the ferroelectricity of the as-obtained ferroelectric HfO_(2)thin ***,the crystallization of o-phase HfO_(2)can be thermodynamically modulated via interfacial stress *** this paper,the growth of improved ferroelectric Al doped HfO_(2)(HfO_(2):Al)thin films on(111)-oriented Si substrate has been *** analysis has suggested that nonpolar monoclinic HfO_(2):Al grown on(111)-oriented Si substrate suffered from a strong compressive strain,which promoted the crystallization of(111)-oriented o-phase HfO_(2)in the as-grown HfO_(2):Al thin *** addition,the in-plane lattice of(111)-oriented Si substrate matches well with that of(111)-oriented o-phase HfO_(2),which further thermally stabilizes the o-phase HfO_(2).Accordingly,an improved ferroelectricity with a remnant polarization(2P_(r))of 26.7C/cm^(2) has been *** results shown in this work provide a simple way toward the preparation of improved ferroelectric HfO_(2)thin films.

关键词： improved ferroelectricity interfacial stress engineering compressive strain HfO_(2)

Long-term monitoring of cycles in Clethrionomys rutilus in the Yukon boreal forest

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Integrative Zoology 2024年第1期19卷 27-36页

作者： Charles J.KREbS Alice J.KENNEY b.Scott GILbERT Rudy bOONSTRA Department of Zoology University of British ColumbiaVancouverBritish ColumbiaCanada Renewable Resources Management Program Yukon UniversityWhitehorseYukonCanada Department of biological Sciences University of Toronto ScarboroughTorontoOntarioCanada

baseline studies of small rodent populations in undisturbed ecosystems are *** report here 50 years of mon-itoring and experimentation in Yukon of a dominant rodent species in the North American boreal forest,the red-backed vole Clethrionomys *** voles breed in summer,weigh 20–25 g,and reach a maximum density of 20 to 25 per *** populations have shown consistent 3–4-year cycles for the last 50 years with the only change being that peak densities averaged 8/ha until 2000 and 18/ha since that *** the last 25 years,we have measured food resources,predator numbers,and winter weather,and for 1-year social interactions,to estimate their contribution to changes in the rate of summer increase and the rate of overwinter *** these potential limiting factors could contribute to changes in density,and we measured their relative contributions statistically with multiple *** rate of winter decline in density was related to both food supply and winter *** rate of summer increase was related to summer berry crops and white spruce cone *** measure of predator numbers was related to winter or summer changes in vole *** was a large signal of climate change effects in these *** is no density dependence in summer population growth and only a weak one in winter population *** of our results provide a clear understanding of what generates 3–4-year cycles in these voles,and the major missing piece may be an understanding of social interactions at high density.

关键词： boreal forest climate change density dependence population cycles predation winter severity