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Arsenic and sulfur nanoparticle synthesis mimicking environmental conditions of submarine shallow-water hydrothermal vents

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Journal of Environmental Sciences 2022年第1期34卷 301-312页

作者： Vicente Durán-Toro Kurosch Rezwan Solveig i.Bühring Michael Maas MARUM–Center for Marine Environmental Sciences University of BremenBremen 28359Germany Advanced Ceramics University of BremenBremen 28359Germany MAPEX-Center for Materials and Processes University of BremenBremen 28359Germany

Arsenic and sulfur mineralization is a natural phenomenon occurring in hydrothermal systems where parameters like temperature and organic matter(OM)can influence the mobilization of the toxic metalloid in marine *** the present study we analyze the influence of temperature and OM(particularly sulfur-containing additives)on As and S precipitation based on the recent discovery of As-rich nanoparticles in the hydrothermal system near the coast of the Greek island *** this end,we experimentally recreate the formation of amorphous colloidal particles rich in As and S via acidification(pH 3–4)of aqueous precursors at various *** higher temperatures,we observe the formation of monodisperse particles within the first 24 h of the experiment,generating colloidal particles with diameters close to 160 *** S:As ratio and particle size of the synthetized particles closely correlates with values for As_(x)S_(y)particles detected in the hydrothermal system off ***,organic sulfur containing additives(cysteine and glutathione,GSH)are a key factor in the process of nucleation and growth of amorphous colloidal As_(x)S_(y)particles and,together with the temperature gradient present in shallow hydrothermal vents,dictate the stabilization of As-bearing nanomaterials in the *** on these findings,we present a simple model that summarizes our new insights into the formation and mobility of colloidal As in aquatic *** this context,amorphous As_(x)S_(y)particles can present harmful effects to micro-and macro-biota not foreseen in bulk As material.

关键词： Biomineralization Milos Hydrothermal vent Arsenic Sulfur nanoparticles Ecotoxicology

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On the connection between the solutions to the Dirac and Weyl equations and the corresponding electromagnetic four-potentials

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Communications in Theoretical Physics 2020年第4期72卷 52-63页

作者： Aristides i Kechriniotis Christos A Tsonos Konstantinos K Delibasis Georgios n Tsigaridas Department of Physics University of ThessalyGR 35100 LamiaGreece Department of Computer Science and Biomedical informatics University of ThessalyGR-35100 LamiaGreece Department of Physics School of Applied Mathematical and Physical SciencesNational Technical University of AthensGR-15780 Zografou AthensGreece

in this work we study in detail the connection between the solutions to the Dirac and Weyl equations and the associated electromagnetic ***,it is proven that all solutions to the Weyl equation are degenerate,in the sense that they correspond to an infinite number of electromagnetic *** far as the solutions to the Dirac equation are concerned,it is shown that they can be classified into two *** elements of the first class correspond to one and only one four-potential,and are called non-degenerate Dirac *** the other hand,the elements of the second class correspond to an infinite number of four-potentials,and are called degenerate Dirac ***,it is proven that at least two of these fourpotentials are gauge-inequivalent,corresponding to different electromagnetic *** order to illustrate this particularly important result we have studied the degenerate solutions to the forcefree Dirac equation and shown that they correspond to massless *** have also provided explicit examples regarding solutions to the force-free Weyl equation and the Weyl equation for a constant magnetic *** all cases we have calculated the infinite number of different electromagnetic fields corresponding to these ***,we have discussed potential applications of our results in cosmology,materials science and nanoelectronics.

关键词： Dirac equation Weyl equation degenerate solutions electromagnetic four-potentials electromagnetic fields massless particles

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Environmental performance assessments of different methods of coal preparation for use in small-capacity boilers: experiment and theory

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international Journal of Coal Science & Technology 2023年第5期10卷 57-71页

作者： A.n.Kozlov E.P.Maysyuk i.Yu.ivanova Melentiev Energy Systems institute of Siberian Branch of the Russian Academy of Sciences Irkutsk130Lermontov664033Russia

The purpose of this article is to receive environmental assessments of combustion of different types of coal fuel depending on the preparation(unscreened,size-graded,briquetted and heat-treated)in automated boilers and boilers with manual *** assessments were made on the basis of data obtained from experimental methods of coal preparation and calculated methods of determining the amount of pollutant and greenhouse gas emissions,as well as the mass of ash and slag *** main pollutants from coal combustion are calculated:particulate matter,benz(a)pyrene,nitrogen oxides,sulfur dioxide,carbon *** the greenhouse gases carbon dioxide is *** a result of conducted research it is shown that the simplest preliminary preparation(size-graded)of coal significantly improves combustion efficiency and environmental performance:emissions are reduced by 13%for hard coal and up to 20%for brown *** introduction of automated boil-ers with heat-treated coal in small boiler facilities allows to reduce emissions and ash and slag waste by 2-3 *** best environmental indicators correspond to heat-treated lignite,which is characterized by the absence of sulfur dioxide emissions.

关键词： Coal preparation Automated and hand-fed coal boilers Environmental performance metrics

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Effect of nb addition on the microstructural,mechanical and electrochemical characteristics of AlCrFeniCu high-entropy alloy

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international Journal of Minerals,Metallurgy and Materials 2020年第10期27卷 1332-1340页

作者： n.Malatji A.P.i.Popoola T.Lengopeng S.Pityana Tshwane University of Technology PretoriaSouth Africa Council for Scientific and industrial Research PretoriaSouth Africa

AlCrFeniCunbx(x=0.05,0.15,and 0.26)high-entropy alloys(HEAs)were successfully fabricated using the laser metal deposition *** laser power of 1600 W and scanning speed of 1.2 m/min were used during laser processing of the *** microstructural,mechanical,and electrochemical characteristics of the alloys were evaluated using various advanced characterization *** showed that the alloys exhibited a dual-phase structure with dendritic *** inclusion of nb in the AlCrFeniCu alloy matrix promoted the formation of fine eutectic structures and changed the shape of the grains from columnar to *** Cu content decreased with the increase in the content of nb,whereas the Al content increased with the increase in the content of *** findings indicated that the presence of nb in the alloy promoted the formation and enhanced the stability of the body-centered cubic(bcc)*** of the alloys that contained nb also exhibited high hardness,compressive strength,and wear ***,the low current density and positive shift in potential exhibited by HEAs with appropriate addition of nb highlighted the superior anticorrosive properties.

关键词： high-entropy alloys microstructure microhardness friction wear loss corrosion resistance

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Approximation of Rainfall Erosivity Factors in north Jordan

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Pedosphere 2010年第6期20卷 711-717页

作者： n.i.ELTAiF M.A.GHARAiBEH F.AL-ZAiTAWi M.n.ALHAMAD Department of natural Resources and Environment Faculty of AgricultureJordan University of Science and Technology

Despite being in arid and semi-arid areas,erosion is largely a result of infrequent but heavy rainfall events; therefore,rainfall erosivity data can be used as an indicator of potential erosion *** purpose of this study was to investigate the spatial distribution of annual rainfall erosivity in north Jordan.A simplified procedure was used to correlate erosivity factor R values in both the universal soil loss equation (USLE) and the revised universal soil loss equation (RUSLE) with annual rainfall amount or modified Fournier index (F mod ).Pluviometric data recorded at 18 weather stations covering north Jordan were used to predict R *** annual values of erosivity ranged between 86-779 MJ mm ha ?1 h ?1 year ?1 .The northwest regions of Jordan showed the highest annual erosivity values,while the northeastern regions showed the lowest annual erosivity values.

关键词： erosion Fournier index iso-erodent map universal soil loss equation

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Generation of dual and quad‑optical frequency combs in the injected radiation free mode‑locked frequency‑shifted feedback laser

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Frontiers of Optoelectronics 2023年第3期16卷 43-56页

作者： Sergey n.Mantsevich Ekaterina i.Kostyleva Andrey n.Danilin Vladimir S.Khorkin Physics Department M.V.Lomonosov Moscow State UniversityMoscow 119991Russia Russian Quantum Center(RQC) Skolkovo 143026Russia

The results of an optoelectronic system—frequency-shifted feedback(FSF)laser experimental examination are *** considered FSF laser is seeded only with optical amplifer spontaneous emission(ASE)and operates in the mode-locked regime,whereby the output radiation is sequence of short pulses with a repetition rate determined by the delay time in its optical feedback *** the frequency domain,the spectrum of such a pulse sequence is an optical frequency comb(OFC).These OFCs we call *** consider the possibility of tunable acousto-optic(AO)dual and quad-comb frequency spacing downconversion in the FSF laser seeded with ASE and operating in the mode-locked *** examined system applies a single frequency shifting loop with single AO tunable flter as the frequency shifter that is fed with several radio frequency signals *** initial OFCs with frequency spacing of about 6.5 MHz may be obtained in the wide spectral range and their width,envelope shape and position in the optical spectrum may be *** dual-combs are obtained with a pair of initial OFCs aroused by two various ultrasound waves in the acousto-optic tunable flter(AOTF).The dual-combs frequency spacing is determined by the frequency diference of the signals applied to the AOTF piezoelectric transducer and can be tuned *** quad-combs are obtained with three initial OFCs,forming a pair of dual-combs,appearing when three ultrasound frequencies feed the AOTF *** quad-combs frequency spacing is defned by the diference between the frequency spacing of ***-combs with more than 5000 spectral lines and tunable frequency spacing are *** successive frequency downconversion gives the possibility to reduce the OFC frequency spacing form several MHz for initial OFC to tens of kHz for quad-combs.

关键词： Frequency-shifted feedback laser Optical frequency combs Acousto-optics Dual-combs Quad-combs

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Framing Shaping Outcomes:issues Related to Mitigation in the UnFCCC negotiations

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Fudan Journal of the Humanities and Social Sciences 2020年第3期13卷 375-394页

作者： M.n.i.Sorkar Fudan University ShanghaiChina Dhaka Bangladesh

Actors purposefully frame up their issues in multilateral negotiations to reach their desired *** were the issues related to mitigation framed up during the two decades of climate negotiations that yielded the Paris Agreement,what was the mechanism for the evolution of the frames and why did only certain crucially contested frames find traction?in these quests,this work conducts a simultaneous content and frame analysis by applying the framing theory and maps the historic evolution pathways of the related *** qualitative analysis identifies a process of frame generation through the contested rhetoric framing by the actors,in line with their primary logics which were shaped by their mental *** finds that the act of framing was the sine-qua-non for the sustenance and traction of the issues,but the fates of the crucially contested frames were determined by the powerful *** the concept of framing allows the systematic visualization of the negotiation process related to Greenhouse Gas mitigation at the annual conferences of the United nations Framework Convention on Climate Change and helps explain how and why certain outcomes appeared.

关键词： Climate negotiations Framing GHG mitigation Paris Agreement Process tracing

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Magnetic properties of Sn-substituted ni-Zn ferrites synthesized from nano-sized powders of niO, ZnO, Fe2O3, and SnO2

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Chinese Physics B 2017年第7期26卷 377-382页

作者： M A Ali M M Uddin M n i Khan F U Z Chowdhury S M Hoque S i Liba Department of Physics Chittagong University of Engineering and Technology (CUET) Materials Science Division Atomic Energy Center

A series of ni0.6-x/2Zn0.4-x/2SnxFe2O4(x = 0.0, 0.05, 0.1, 0.15, 0.2, and 0.3)(nZSFO) ferrite composities have been synthesized from nano powders using a standard solid state reaction technique. The spinel cubic structure of the investigated samples has been confirmed by x-ray diffraction(XRD). The magnetic properties such as saturation magnetization(Ms),remanent magnetization(Mr), coercive field(Hc), and Bohr magneton(μ) are calculated from the hysteresis loops. The value of Msis found to decrease with increasing Sn content in the samples. This change is successfully explained by the variation of A-B interaction strength due to Sn substitution in different sites. The compositional stability and quality of the prepared ferrite composites have also been endorsed by the fairly constant initial permeability(μ’) over a wide range of frequency. The decreasing trend of μ’ with increasing Sn content has been observed. Curie temperature TChas been found to increase with the increase in Sn content. A wide spread frequency utility zone indicates that the nZSFO can be considered as a good candidate for use in broadband pulse transformers and wide band read-write heads for video recording. The composition of x = 0.05 shows unusual results and the possible reason is also mentioned with the established formalism.

关键词： magnetic properties saturation magnetization permeability Curie temperature

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Quantization of the O（n） nonlinear Sigma Model

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Communications in Theoretical Physics 2002年第5期37卷 567-570页

作者： S.i.Muslih DepartmentofPhysics Al－AzharUniversityGazaPalestine

The Hamilton-Jacobi method of quantizing singular systems is discussed. The equations of motion areobtained as total differential equations in many variables. it is shown that if the system is integrable, one can obtain thecanonical phase space coordinates and set of canonical Hamilton-Jacobi partial differential equations without any needto introduce unphysical auxiliary fields. As an example we quantize the O(2) nonlinear sigma model using two differentapproaches: the functional Schrodinger method to obtain the wave functionals for the ground and the exited state andthen we quantize the same model using the canonical path integral quantization as an integration over the canonicalphase-space coordinates.

关键词：量子力学 O(n)非线性Sigma模型量子化

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Enhancement of coercivity,permeability,and dielectric properties of Co_(0.2)Zn_(0.3)ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites for memory and high frequency devices

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Journal of Rare Earths 2024年第6期42卷 1128-1135,I0005页

作者： i.Sardar M.D.Hossain M.S.Sikder M.n.i.Khan M.R.Rahman Physics Discipline Khulna UniversityKhulna9208Bangladesh Department of Physics Khulna University of Engineering&TechnologyKhulna9203Bangladesh Department ofComputer Science and Engineering Northern University of Business&Technology KhulnaKhulna9100Bangladesh Material Science Division Atomic Energy CentreDhaka1000Bangladesh

Spinel cubic ferrites have huge applications in me mory and high frequency *** the improvement of these modern devices,the magnetic coercivity,permeability,and dielectric properties of a ferrite are the important *** article focuses on improving the magnetic coercivity,magnetic permeability,and dielectric properties of Co_(0.2)Zn_(0.3)ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites,where x=0.00,0.06,and *** X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTiR),field emission scanning electron microscopy(FESEM),energy dispersive X-ray(EDX),vibrating sample magnetometer(VSM),and an impedance analyzer were used to characterize the structural,magnetic,and dielectric properties of the *** XRD patterns indicate the formation of spinel cubic structure of the samples with a secondary peak(EuFeO_(3))for Eu doped *** densities and porosities of the samples follow an inverse trend,where the doped samples’lattice parameters are increased with the increment of rare earth Eu *** FTiR analysis also proves the spinel cubic phase of the *** average grain size of the ferrites is obtained via FESEM images,and it is increased from 121 to 198 *** analysis confirms that doping of the Eu content also changes other hysteresis loop properties of Co_(0.2)Zn_(0.3)ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ***,the coercivity of the Eu doped samples is greater than that of the mother alloy(x=0.00).The EDX study shows that there is no impurity contamination in the *** permeability and dielectric measurements show an improved quality factor of the Eu-doped samples with low magnetic and dielectric *** dependent resistivity and impedance analysis also show the improved *** the observed properties of the samples,all the investigated ferrites might be strong candidates for potential applications in memory devices,magnetic sensors,and high frequency applications.

关键词： Ferrites Raree arths Coercivity Permeability EDX Resistivity

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