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Influence of cerium ions on structure-dependent magnetic properties of Ba-Sr m-type hexaferrite nanocrystals

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Journal of Rare Earths 2024年第2期42卷 364-372,I0005页

作者： Ram A.pawar Sunil m.patange p.m.Dighe Sher Singh meena Abdullah GAl-Sehemi mehboobali pannipara Santosh S.Jadhav Department of physics ArtsCommerce and Science CollegeAhmednagar413711MaharashtraIndia Department of physics Shri Krishna MahavidyalayaGunjotiDistOsmanabad413606MaharashtraIndia padmashri Vikhe patil College of Arts Science and CommercePravaranagarA/P.Loni(Kd)Tal.RahataDistAhmednagar413713MaharashtraIndia Solid State physics Division Bhabha Atomic Research CentreMumbai400085MaharashtraIndia Department of Chemistry King Khalid UniversityAbha61413Saudi Arabia Department of physics D.S.M's ArtsCommerce and Science CollegeJintur431509MaharashtraIndia

The present study is a systematic effort to investigate the structure-sensitive magnetic parameters of Ce^(3+) substituted Ba-Sr hexaferrite nanocrystals chemically formulated as Ba_(0.5)Sr_(0.5)Ce_(x)Fe_(12-x)O_(19) where x=0.0-0.2 with Δx=*** hexaferrite powders were prepared using the sol-gel self-ignition route and structurally characterized by means of powder X-ray diffraction and Fourier transform infrared *** creation of the m-type hexaferrite phase within the synthesized samples was revealed from the Rietveld refinement of the X-ray *** occurrence of a secondary phase of CeO_(2) was revealed within the hexaferrites for the substitution,x> *** refined X-ray diffraction data were utilized to compute the lattice parameters,X-ray density,and lattice parameter *** crystal structure plotted from the refined XRD data reveals the occupancy of the ions at different lattice *** XpS data of the hexaferrite were analyzed to confirm the oxidation states of the constituent *** nanocrystalline nature of the hexaferrites was revealed from the crystallite sizes calculated using Scherer's *** analysis of FTIR spectra confirms that only a fraction of Ce^(3+)accommodated in the lattice and the remaining Ce content reside in the form of the CeO_(2) *** morphology of the hexaferrites was analyzed from the FESEm profiles of the ferrite *** magnetic behavior study was performed by analyzing the Curie temperature,hysteresis loops,and hyperfine interactions by means of susceptibility,V.S.m,and mossbauer spectroscopy,*** hexaferrites with increasing coercivity,decreasing saturation magnetization,and decreasing Curie temperature are reported in the *** substituted Ce^(3+)ions inhibit the grain growth and create lattice imperfections giving rise to hexaferrites with tuned magnetic parameters suitable for different applications.

关键词： Ba-Sr hexaferrite Ce^(3+)substitution XpS Saturation magnetization Coercivity m?ssbauer spectroscopy

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乳液聚合数学模型

化工学报 1982年第1期 14-25页

作者：曹同玉 A.J.merry m.p.wilson 天津大学化工系 International Ltd. University of Aston Birmingham U.K. Whitchcurch Dep.of Chem.Eng. patterson Candv U.k. Hants

本文报导了在50℃下苯乙烯乳液聚合和悬浮聚合的试验研究。对在无挡板搅拌釜中的间歇乳液聚合提出了一个数学模型。这个模型不仅考虑了吸附在单体珠滴表面上的乳化剂的影响,而且考虑到凝胶效应。模型所需要的终止速度常数与转化率之间... 详细信息

本文报导了在50℃下苯乙烯乳液聚合和悬浮聚合的试验研究。对在无挡板搅拌釜中的间歇乳液聚合提出了一个数学模型。这个模型不仅考虑了吸附在单体珠滴表面上的乳化剂的影响,而且考虑到凝胶效应。模型所需要的终止速度常数与转化率之间的依赖关系是从悬浮聚合的试验数据整理而成的。结果表明,本模型可以在相当宽的转化率范围内成功地预计转化速率和胶乳中的颗粒尺寸及数目。

关键词：单体依赖关系乳液聚合转化率凝胶效应珠滴速度常数数学模型试验模型苯乙烯

乳液聚合数学模型Ⅰ.吸附在单体珠滴上的乳化剂对乳液聚合的影响

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天津大学学报 1981年第4期 44-58页

作者：曹同玉 A.J.merry m.p.wilson patterson Candy International Ltd. Whitchurch Hauts U. K. Chem. Eng. Depart. University of Aston Birmingham

本文研究了在低乳化剂浓度下苯乙烯的乳液聚合,建立了一个考虑到吸附在单体珠滴表面上乳化剂的数学模型。发现,在低乳化剂浓度下和在高搅拌转速下本模型比经典模型可以更有效地予计乳液聚合的性能。结果表明,模型的予计很好地符合试验... 详细信息

本文研究了在低乳化剂浓度下苯乙烯的乳液聚合,建立了一个考虑到吸附在单体珠滴表面上乳化剂的数学模型。发现,在低乳化剂浓度下和在高搅拌转速下本模型比经典模型可以更有效地予计乳液聚合的性能。结果表明,模型的予计很好地符合试验结果。

关键词：珠滴聚合物胶束大分子化合物胶态离子单体乳化剂农药助剂乳液聚合数学模型试验模型

mechanisms behind the environmental sensitivity of carbon fiber reinforced polytetrafluoroethylene(pTFE)

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Friction 2024年第5期12卷 997-1015页

作者： pontus JOHANSSON p.mARKLUND m.BJORLING Y.SHI Division of machine Element LuleåUniversity of TechnologyLuleåSE-97187Sweden

Carbon fiber reinforced polytetrafluoroethylene (CF/pTFE) composites are known for their exceptional tribological performance when sliding against steel or cast iron in inert gas environments. Compared to experiments in humid air, about an order of magnitude lower wear rate and several times lower coefficient of friction have been reported for tests conducted in dry nitrogen and hydrogen. moreover, trace moisture has been shown to affect the friction and wear significantly of this tribosystem, although a possible effect of oxygen cannot be ruled out due to uncertainties regarding the oxygen concentrations. While several studies have pointed out the environmental sensitivity of CF/pTFE, the understanding of the underlying mechanisms are very limited. The objective of this research is to investigate the individual and combined effect of oxygen and moisture on the tribological behavior of CF/pTFE sliding against steel. Additionally, this study aims to elucidate the underlying mechanisms that govern the environmental sensitivity of the system. Climate-controlled three-pin-on-disc experiments were conducted in nitrogen atmospheres at various concentrations of oxygen and moisture. The tribological results clearly demonstrate that both moisture and oxygen contribute to increased friction and wear. However, the adverse effect was much more pronounced for oxygen than moisture. A qualitative method was developed to estimate the tribofilm coverage on the CF/pTFE surface. Results showed strong correlation between high coverage of strongly adhered tribofilm and low wear rate. moreover, a loosely adhered tribofilm was observed on top of the CF/pTFE surface in presence of moisture. FTIR analysis indicated that the loosely adhered tribofilm found in the moisture-enriched environment contained a significant amount of adsorbed water, which may explain the lower coefficient of friction in presence of moisture compared to oxygen. The adsorbed water in the loosely adhered tribofilm coul

关键词： polymer composite tribofilm tribochemistry atmosphere

Drought events influence nutrient canopy exchanges and green leaf partitioning during senescence in a deciduous forest

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Forest Ecosystems 2024年第1期11卷 110-119页

作者： J.Touche C.Calvaruso p.De Donato m.-p.Turpault INRAE BEFF-54000NancyFrance UmR 7359 GeoRessourcesFaculte des Sciences-Campus des Aiguillettes54506Vandoeuvre Les NancyFrance EcoSustain Environmental Engineering OfficeResearch and DevelopmentKanfen57330France

The increase in the frequency and intensity of drought events expected in the coming decades in Western Europe may disturb forest biogeochemical cycles and create nutrient deficiencies in *** possible origin of nutrient deficiency is the disturbance of the partitioning of the green leaf pool during the leaf senescence period between resorption,foliar leaching and senesced ***,the effects of drought events on this partitioning and the consequences for the maintenance of tree nutrition are poorly *** experiment in a beech forest in meuse(France)was conducted to assess the effect of drought events on nutrient canopy exchanges and on the partitioning of the green leaf pool during the leaf senescence *** aim was to identify potential nutritional consequences of droughts for *** nutrient dynamics,including resorption,chemistry of green and senesced leaves,foliar absorption and leaching in mature beech stands from 2012 to 2019 allowed us to compare the nutrient exchanges for three nondry and three dry years(i.e.,with an intense drought event during the growing season).During dry years,we observed a decrease by almost a third of the potassium(K)partitioning to resorption(*** efficiency),thus reducing the K reserve in trees for the next growing *** result suggests that with the increased drought frequency and intensity expected for the coming decades,there will be a risk of potassium deficiency in trees,as already observed in a rainfall exclusion experiment on the same study *** foliar leaching and higher parititioning to the senesced leaves for K and phosphorus(p)were also *** addition,a slight increase in nitrogen(N)resorption efficiency occurred during dry years which is more likely to improve tree *** calcium(Ca)negative resorption decreased,with no apparent consequence in our study *** results show that nutrient exchanges in the canopy and the partitioning of the green leaf

关键词： Natural drought Beech forest Canopy Resorption Foliar leaching Senesced leaves Nutrition

Intertype superconductivity evoked by the interplay of disorder and multiple bands

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Frontiers of physics 2024年第4期19卷 81-89页

作者： p.m.marychev A.A.Shanenko A.V.Vagov HSE University 101000 MoscowRussia Center for Advanced mesoscience and Nanotechnology MIPTDolgoprudny141700Russia

Nonmagnetic impurity scattering is known to shift up the Ginzburg-Landau parameter k of a *** this case,when the system is initially in type I,it can change its magnetic response,crossing the intertype domain with k~1 between the two standard superconductivity types and arriving at type *** the present work we demonstrate that the impact of disorder can be much more profound in the presence of the multiband structure of the charge carrier *** particular,when the band diffusivities differ from each other,the intertype domain tends to expand significantly,including points with k>1 that belong to deep type-Ⅱ in conventional single-band *** finding sheds light on the nontrivial disorder effect and significantly complements earlier results on the enlargement of the intertype domain in clean multiband superconductors.

关键词： superconductivity disorder intertype superconductivity twoband model

The effects of data aggregation on long-term projections of forest stands development

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Forest Ecosystems 2024年第3期11卷 381-389页

作者： Kobra maleki Rasmus Astrup Nicolas Cattaneo wilson Lara Henao Clara Anton-Fernandez Norwegian Institute of Bioeconomy Research Division of Forestry and Forest ResourcesP.O.Box 115ÅsNO-1431Norway

Forest management planning often relies on Airborne Laser Scanning(ALS)-based Forest management Inventories(FmIs)for sustainable and efficient *** the area-based(ABA)approach,these inventories estimate forest characteristics for grid cell areas(pixels),which are then usually summarized at the stand *** the ALS-based high-resolution Norwegian Forest Resource maps(16 m×16 m pixel resolution)alongside with stand-level growth and yield models,this study explores the impact of three levels of pixel aggregation(standlevel,stand-level with species strata,and pixel-level)on projected stand *** results indicate significant differences in the projected outputs based on the aggregation ***,the most substantial difference in estimated volume occurred between stand-level and pixel-level aggregation,ranging from-301 to+253 m^(3)·ha^(-1)for single *** differences were,on average,higher for broadleaves than for spruce and pine dominated stands,and for mixed stands and stands with higher variability than for pure and homogenous *** conclusion,this research underscores the critical role of input data resolution in forest planning and management,emphasizing the need for improved data collection practices to ensure sustainable forest management.

关键词： Growth and yield models Dominant species Norway spruce Scots pine Broadleaves Forest resource map Stand variability

Exact solutions for magnetohydrodynamic nanofluids flow and heat transfer over a permeable axisymmetric radially stretching/shrinking sheet

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Chinese physics B 2024年第2期33卷 108-114页

作者： U.S.mahabaleshwar G.p.Vanitha L.m.pérez Emad H.Aly I.pop Department of Studies in mathematics Davangere UniversityShivagangothriDavangereIndia Departamento de F´ısica FACIUniversidad de Tarapac´aCasilla 7DAricaChile Department of mathematics Faculty of EducationAin Shams UniversityRoxyCairoEgypt Department of mathematics Babes-Bolyai University400084 Cluj-NapocaRomania

We report on the magnetohydrodynamic impact on the axisymmetric flow of Al_(2)O_(3)/Cu nanoparticles suspended in H_(2)O past a stretched/shrinked *** the use of partial differential equations and the corresponding thermophysical characteristics of nanoparticles,the physical flow process is *** resultant nonlinear system of partial differential equations is converted into a system of ordinary differential equations using the suitable similarity *** transformed differential equations are solved *** of the magnetic parameter,solid volume fraction and stretching/shrinking parameter on momentum and temperature distribution have been analyzed and interpreted *** skin friction and Nusselt number were also *** addition,existence of dual solution was deduced for the shrinking sheet and unique solution for the stretching ***,Al_(2)O_(3)/H_(2)O nanofluid flow has better thermal conductivity on comparing with Cu/H_(2)O ***,it was found that the first solutions of the stream are stable and physically realizable,whereas those of the second ones are unstable.

关键词： magnetohydrodynamic nanofluid stretching/shrinking sheet axisymmetric flow analytical solution suction/injection

Laser-induced graphene-coated wearable smart textile electrodes for biopotentials signal monitoring

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Frontiers of materials Science 2024年第1期18卷 95-111页

作者： C.m.Vidhya Yogita maithani Sakshi Kapoor J.p.Singh Department of physics Indian Institute of Technology DelhiHauz KhasNew Delhi 110016India

This paper describes how to produce a wearable dry electrode at a reasonable cost and how to use it for the monitoring of biopotentials in *** textiles in wearable technologies have made a great advancement in the health care management and living standards of *** was manufactured using the low-cost single-step process,laser ablation of polyimide,a commercial *** dispersions were made using solvent isopropyl alcohol which has low boiling point,nontoxicity,and environmental *** successive coating of the graphene dispersion on the cotton fabric to make it conductive,the sheet resistance of the resulting fabric dropped to 3% of its initial *** laser-induced graphene(LIG)cotton dry electrodes thus manufactured are comparable to Ag/AgCl wet electrodes in terms of the skin-to-electrode impedance,measuring between 78.0 and 7.2 kΩ for the frequency between 40 Hz and 1 *** LIG cotton electrode displayed a signal-to-noise ratio of 20.17 *** to its comfort,simplicity,and good performance over a longer period of time,the textile electrode appears suited for medical applications.

关键词： biopotential electrocardiogram electromyogram flexible electrode textile porous graphene