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synthesis of coral-like structures of Pr-Yb co-doped YIG: structural,optical, magnetic and antimicrobial properties

Journal of Rare Earths 2024年第3期42卷 543-554,I0004页

作者： A.Fernandez Francisca P.Araujo Y.Guerra s.castro-Lopes J.Matilla-Arias Idglan s.de Lima Edson C.silva-Filho Josy A.Osajima F.Guerrero R.Pena-Garcia Federal University of Piau Graduate Program in Materials Science and EngineeringTeresinaPIBrazil Federal Rural University of Pernambuco Academic Unit of Cabo de Santo AgostinhoCabo de Santo AgostinhoPEBrazil Federal University of Piaui Department of PhysicTeresinaPBrazil Federal University of Pernambuco Graduate Program in Materials ScienceRecifePEBrazil University of Granma Departmentof Basic Sciences and Applied InformaticsFaculty of Technical SciencesBayamoCuba Federal University of Amazonas Department of PhysicManausAMBrazil Federal University of Pernambuco Department of PhysicRecifePEBrazil

Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona-O-Iondangle, Iona-O,Iond-O and Ionc-O bond distances and decrease in the average crystallite size. Fourier transform infrared(FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy(EDs) spectra and textural properties show corallike structures, peaks associated with Pr^(3+) and Yb^(3+) atoms and the effect of dopants on surface area,diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer,correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12)compound. The saturation magnetization(M_(s)), cubic anisotropy constant(K_(1)) and coercive field(H_(c)) increase with the Pr^(3+)cations content, as consequence of their magnetic nature and distribution around of Fe^(3+)ions due to the coexistence with the Yb^(3+). Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr^(3+)and Yb^(3+)and it is shown that, relatively high dosages of Pr^(3+) cations favored the activity against s. aureus, therefore, a new biological property for YIG doped with rare earths is presented.

关键词： Yttrium iron garnet(YIG) Coral-like structures Rare earths Band gap energy Magnetic properties Antimicrobial properties

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Enhanced Rsa (Ersa): An Advanced Mechanism for Improving the security

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Intelligent Automation & soft Computing 2023年第5期36卷 2267-2279页

作者： s.castro R.PushpaLakshmi Karpagam College of Engineering Coimbatore641032Tamil NaduIndia PsNA College of Engineering And Technology Dindigul624622Tamil NaduIndia

Cloud computing has become ubiquitous in our daily lives in recent *** are the source of technology that is generated hugely by various *** data is dealing with huge data volumes or complex *** major concern in big data is security *** concerns create a negative impact on the user on the aspect of *** big data still,security threats exist as com-monly known as DDOs(Distributed-Denial-of-service)attacks,data loss,Inade-quate Data Backups,system Vulnerabilities,and Phishing as well as social Engineering *** our work,we have taken the data loss and Inadequate Data Backups issues into *** analyze that RsA(Rivest,shamir,&Adleman)is the most secure cryptography *** cloud computing,user authentication is the weaker section to be ***,the cryptogra-phy mechanism is done in the authentication section *** implemented our new idea of registration with selected images and pins for processing *** valid authentication approval earned by the proposed mechanism,the user is allowed to use the cloud database,encryption,decryption,*** prove the efﬁ-ciency level of our proposed system,a comparison work is conducted between DssE(Digital signature standard Encryption)and EFssA(Efﬁcient framework for securely sharing aﬁle using asymmetric key distribution management).The experimental work is carried out and the performance evaluation is done using encryption time and decryption time analysis,throughput,and processing *** this observation,the security level attained by ERsA is far better in compar-ison to DssE and EFssA with the maximum throughput attained by the proposed E-RsA being 500 Mb/Min and encryption time of 3.2 s,thus ensuring the user trust in using the cloud environment.

关键词： Cloud computing encryption decryption ﬁle sharing RsA key generation

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synthesis and evaluation of nickel cobalt ferrite magnetic ceramics employing two alternative routes

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Journal of Advanced Dielectrics 2021年第3期11卷 2-7页

作者： Javier E.Camargo Leandro A.Ramajo Miriam s.castro División Cerámicos INTEMA Instituto de Investigaciones en Ciencia y Tecnología de Materiales(INTEMACONICET-UNMdP)Av.Colón 108507600Mar del PlataArgentina

Ni_(0.5)Co_(0.5)Fe_(2)O_(4)(NCF)powders were obtained employing two alternative synthesis routes:solid-state reaction and Pechini’s *** ceramic powders were pressed and sintered in the temperature range of 1100℃ to 1250℃.Microstructural and structural properties were evaluated by sEM,XRD,and Raman *** hysteresis loops of sintered samples were also recorded.A secondary phase was observed in samples synthesized by Pechini’s method,whereas samples obtained by the solid-state reaction method,with the mechanochemical activation of the reagents,only produced the spinel *** properties of samples obtained by the solid-state method displayed higher magnetic saturations and lower coercive fields than those obtained from the Pechini’s method.

关键词： Ferrite Pechini Raman spectroscopy magnetic properties

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Treatment with Enterococcus faecalis CECT7121 Is Not Effective as Therapy in Mice with an Established Allergy status

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Advances in Microbiology 2017年第10期7卷 696-706页

作者： Ailén M.Díaz Matías A.Molina Guillermo G.Nunez Ana C.Mourelle Mónica D.sparo Marcela A.Manghi Marisa s.castro Facultad de Farmacia y Bioquímica Universidad de Buenos AiresInstituto de Estudios de la Inmunidad Humoral“Prof.Dr.R.A.Margni”(IDEHUCONICET-UBA)Buenos AiresArgentina Cátedra Microbiología y Parasitología(CUDEMyP) Facultad de Ciencias MédicasUniversidad Nacional de La PlataLa PlataArgentina

In allergies, an unbalanced immune response towards a T helper (Th) 2 profile with high levels of Immunoglobulin (Ig) E is produced. We have demonstrated that the pre-administration of Enterococcus faecalis CECT7121 prevents the development of allergy in ovalbumin-immunized mice. In this work, we evaluated whether this bacterium can also revert an established allergic status. Mice were immunized with ovalbumin (OVA) and after that, were inoculated with an E. faecalis CECT7121 suspension. In immunized animals, serum specific immune response, proliferative activity of memory splenocytes, and levels of Th2 cytokines were assessed. The in vivo active cutaneous anaphylaxis test was also performed. The treatment with E. faecalis CECT7121 only increased anti-OVA IgG2a levels. No differences were observed in other specific immunological parameters. Probiotic-treatment did not prove to have any desensitizing effect on mice. These results, together with those recently published, can be concluded that this bacterium would not be appropriate for the treatment of allergic symptoms.

关键词： Enterococcus faecalis CECT7121 Ovalbumin-Allergy Murine Model Immunoglobulin E Th2 Cytokines Probiotics

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Kentish Plover(Charadrius alexandrinus) and Little Tern(sternula albifrons) prefer shells for nesting:A field experiment

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Avian Research 2024年第1期15卷 55-59页

作者： Macarena castro Andrés De la Cruz Nuria Martin-sanjuan Alejandro Pérez-Hurtado Instituto Universitario de Investigacion Marina(INMAR) Campus de Excelencia Internacional del Mar(CEIMAR)Departamento de BiologíaUniversidad de CadizPuerto RealSpain servicios centrales de Investigacion salinas de la Esperanza Universidad de CadizPuerto RealSpain

shorebird populations are declining worldwide,mainly due to human disturbances and loss of coastal ***,supratidal habitats as saltpans could play a role in buffering human *** have shown to be important as feeding or breeding sites of some shorebird species.A potential conservation strategy to increase shorebird populations in saltpans is to manipulate the cues that birds use to select optimal breeding *** it is hypothesized that shorebirds are attracted to bivalve shells due to the advantages they *** this hypothesis,we supplemented a restored saltpan in 2019 and 2021 with bivalve shells,expecting an increase in the number of breeding birds’ *** than 75% of Kentish Plover(Charadrius alexandrinus) and Little Tern(sternula albifrons) nests were found in patches with shells in both *** best model for both species indicates that the presence of shells is the factor that most correlates with the location of *** probability of choosing one place over another to settle their nest increases in areas with an abundance of shells,double in the case of the Kentish Plover and triple in the case of the Little *** result of this study may constitute a valuable tool for attracting birds to restored saltpans and could contribute to the success of expensive restoration projects where time is usually a constraint.

关键词： Habitat management Nest site selection saltpan restoration shell supplementation shorebirds

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Deformation Analysis of Gasoline storage Tanks

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Journal of Civil Engineering and Architecture 2022年第12期16卷 626-631页

作者： Ana Cristina C.F.sieira Luis Fernando s.castro Rio de Janeiro Estate University Brasil sOLUM Consultoria e Engenharia Brasil

This paper aims to study the deformations of the five tanks implanted in a Terminal located in the region of Pará,***,the results of eight standard penetration tests(sPT),carried out around the construction area of the tanks,were analyzed to define a representative geological-geotechnical profile and estimate of geotechnical parameters of the local *** vertical deformations imposed by the construction of the tanks were predicted numerically from the PLAXIs 2D computational program,which performs stress-strain analysis using the finite element *** the prediction of the settlements,it was possible to estimate the maximum settlements and the angular distortions for the foundations of the tanks,comparing with the admissible values.

关键词： Numerical analysis storage tanks settlements and distortions

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Design multifunctional Mg–Zr coatings regulating Mg alloy bioabsorption

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Journal of Magnesium and Alloys 2024年第4期12卷 1461-1478页

作者： Zohra Benzarti sandesh Itani JoséDavid castro sandra Carvalho Ana sofia Ramos University of Coimbra CEMMPREARISEDepartment of Mechanical EngineeringRua Luís Reis Santos3030-788CoimbraPortugal Laboratory of Multifunctional Materials and Applications(LaMMA) Department of PhysicsFaculty of Sciences of SfaxUniversity of SfaxSoukra Road km 3.5B.P.1171Sfax3000Tunisia

Magnesium(Mg)alloys are widely used for temporary bone implants due to their favorable biodegradability,cytocompatibility,hemocompatibility,and close mechanical properties to ***,rapid degradation and inadequate strength limit their *** overcome this,the direct current magnetron sputtering technique is employed for surface coating in Mg-based alloys using various zirconium(Zr)*** approach presents a promising strategy for simultaneously improving corrosion resistance,maintaining biocompatibility,and enhancing strength without compromising *** leveraging Mg’s inherent biodegradability,it has the potential to minimize the need for secondary surgeries,thereby reducing costs and *** paper is a systematic study aimed at understanding the corrosion mechanisms of Mg–Zr coatings,denoted Mg-xZr(x=0–5 at.%).Zr-doped coatings exhibited columnar growth leading to denser and refined structures with increasing Zr *** analysis confirmed the presence of the Mg(00.2)basal plane,shifting towards higher angles(1.15°)with 5 at.%Zr doping due to lattice parameter changes(i.e.,decrease and increase of“c”and“a”lattice parameters,respectively).Mg–Zr coatings exhibited“liquidphilic”behavior,while Young’s modulus retained a steady value around 80 GPa across all ***,the hardness has significantly improved across all samples’coating,reaching the highest value of(2.2±0.3)GPa for 5 at.%*** testing in simulated body fluid(sBF)at 37℃ revealed a significant enhancement in corrosion resistance for Mg–Zr coatings containing 1.0–3.4 at.%*** with the 5 at.%Zr coating which exhibited a corrosion rate of 32 mm/year,these coatings displayed lower corrosion rates,ranging from 1 to 12 mm/*** synergistic enhancement in mechanical properties and corrosion resistance,achieved with 2.0–3.4 at.%Zr,suggests potential ability for reducing stress shielding and controlled degradation performance,and consequentl

关键词： Mg-Zr coatings Magnetron sputtering Nanoindentation Corrosion resistance Bone implants

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A Novel Derivation of Black Hole Entropy in all Dimensions from Truly Point Mass sources

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Journal of High Energy Physics, Gravitation and Cosmology 2024年第3期10卷 1017-1028页

作者： Carlos.castro Perelman Bahamas Advanced science Institute and Conferences Ocean Heights Stella Maris Long Island Bahamas Ronin Institute Haddon Place Montclair USA

It is explicitly shown how the schwarzschild Black Hole Entropy (in all dimensions) emerges from truly point mass sources at r=0due to a non-vanishing scalar curvature involving the Dirac delta distribution. In order to achieve this, one is required to extend the domain of r to negative values −∞≤r≤+∞. It is the density and anisotropic pressure components associated with the point mass delta function source at the origin r=0which furnish the schwarzschild black hole entropy in all dimensions D≥4after evaluating the Euclidean Einstein-Hilbert action. Two of the most salient results are i) that the observed spacetime dimension D=4is precisely singled out from all the other dimensions when the strong and weak energy conditions are met, and ii) the point mass source described in this work is not the result of a spherically symmetric gravitational collapse of a star as described by the Oppenheimer-snyder model because we are not neglecting the pressure. As usual, it is required to take the inverse Hawking temperature βHas the length of the circle sβ1obtained from a compactification of the Euclidean time in thermal field theory which results after a Wick rotation, it=τ, to imaginary time. This approach can be generalized to the Reissner-Nordstrom and Kerr-Newman metrics. The physical implications of this finding warrant further investigation since it suggests a profound connection between the notion of gravitational entropy and spacetime singularities.

关键词： General Relativity Black Holes Entropy strings

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snapshot survey of the Presence of Perfluoroalkyl substances in Products, Articles, and the Environment in Ecuador

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Engineering 2024年第6期37卷 49-61页

作者： Heidelore Fiedler Luis Vega-Bustillos Jenny Arias-Pastrano Lander Vinicio Pérez-Aldás Jose castro-Díaz MTM Research Centre School of Science and TechnologyÖrebro UniversityÖrebro 70182Sweden Undersecretariat of Environmental Quality Ministry of EnvironmentWater and Ecological Transition of EcuadorQuito 170525Ecuador Department of Environmental Chemistry The Technical University of AmbatoHuachi CampusAmbato 180207Ecuador Alternativavision Ambiental Cia.Ltda. Mexico 03100Mexico

The stockholm Convention on Persistent Organic Pollutants(POPs)is a legally binding instrument for 186 Parties(status:April 2023).Accordingly,among other responsibilities,countries are obliged to report the production,import,or export of the POPs listed in Annexes A,B,or C;provide information to registers;maintain inventories;and monitor the presence of POPs in the *** the broader context of international chemicals and waste management,producer responsibilities,harmonized reporting,and compliance with national and international regulations,Ecuador has addressed the newly listed group of perfluorinated alkyl substances(PFAs)in its national implementation plan and sent selected products from its national market for PFAs *** products analyzed came from the initially listed fields of specific exemptions and acceptable purposes,including:fire-fighting foams;photographic aids;greasers/degreasers;various kinds of paper/packaging;textiles;and leather,coatings,cleaners,metal plating,and *** results showed that the three PFAs presently listed in the stockholm Convention could be quantified in only a few samples;additional PFAs,not yet listed in the Convention also had low detection *** the number of samples was limited,the samples covered a large spectrum of sample matrices,making it possible to conclude that—once these products become waste and are regulated under the Basel Convention—they would not constitute a disposal ***,verification of the presence of PFAs in products on the market is expected to pose an analytical challenge for both,developed and developing countries.

关键词： Emerging or newly listed POPs stockholm Convention Products and articles PFAs analysis Developing countries

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From strength to precision: A systematic review exploring the clinical utility of 7-Tesla magnetic resonance imaging in abdominal imaging

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World Journal of Radiology 2024年第1期16卷 20-31页

作者： Arosh s Perera Molligoda Arachchige Ana Claudia Teixeira de castro Gonçalves Ortega Federica Catapano Letterio s Politi Michael N Hoff Faculty of Medicine Humanitas UniversityPieve Emanuele 20072MilanItaly Department of Biomedical sciences Humanitas UniversityPieve Emanuele 20072MilanItaly IRCCs Humanitas Research Hospital Rozzano 20089MilanItaly Department of Neuroradiology IRCCS Humanitas Research HospitalRozzano 20089MilanItaly Department of Radiology and Biomedical Imaging University of CaliforniaSan FranciscoCA 94143United States

BACKGROUND After approval for clinical use in 2017 early investigations of ultra-high-field abdominal magnetic resonance imaging(MRI)have demonstrated the feasibility as well as diagnostic capabilities of liver,kidney,and prostate MRI at ***,the elevation of the field strength to 7-Tesla not only brought advantages to abdominal MRI but also presented considerable challenges and drawbacks,primarily stemming from heightened artifacts and limitations in specific Absorption Rate,***,evidence in the literature is relatively scarce concerning human studies in comparison to phantom/animal studies which necessitates an investigation into the evidence so far in humans and summarizing all relevant *** To offer a comprehensive overview of current literature on clinical abdominal 7T MRI that emphasizes current trends,details relevant challenges,and provides a concise set of potential *** This systematic review adheres to Preferred Reporting Items for systematic Reviews and Meta-Analyses guidelines.A PubMed search,utilizing Medical subject Headings terms such as"7-Tesla"and organ-specific terms,was conducted for articles published between January 1,1985,and July 25,*** criteria included studies exploring 7T MRI for imaging human abdominal organs,encompassing various study types(in-vivo/ex-vivo,method development,reviews/meta-analyses).Exclusion criteria involved animal studies and those lacking extractable *** selection involved initial identification via title/abstract,followed by a full-text review by two researchers,with discrepancies resolved through *** extraction covered publication details,study design,population,sample size,7T MRI protocol,image characteristics,endpoints,and *** The systematic review included a total of 21 *** distribution of clinical 7T abdominal imaging studies revealed a predominant focus on the prostate(n=8),followed by the kidney(n=6)and the hepato

关键词： 7-Tesla magnetic resonance imaging Abdominal Prostate Kidney Renal Pancreas Hepatobiliary Liver small bowel

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