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Materials Sciences and Applications 2013年第9期4卷 549-555页

作者： Alexandre Goncalves Pinheiro Gilberto Dantas Saraiva Josué Mendes Filho antonio sergio bezerra sombra Faculdade de Educacao Ciencias e Letras do Sertao Central Universidade Estadual do CearáQuixadáBrazil Departamento de Fisica Universidade Federal do CearáFortalezaBrazil

We prepared the Nano-sized bismuth titanate Bi4Ti3O12 (BIT) powders, through a high-energy ball milling process from their oxides Bi2O3 and TiO2. This BIT phase can be formed after a milling process for 40 min. With an increasing milling time, this particle size of mixture is gradually reduced, thus, we have mostly an amorphous phase. The BIT ceramics were duly obtained by sintering the synthesized powders at temperatures ranging from 850°C to 1000°C. The BIT ceramics sintered at 1020°C for 1 h, exhibiting a density with 7.52 g/cm3 of a crystaline phase and a dielectric of K = 288.11 (100 Hz), as well as a dielectric loss of 0.05 (100 kHz). The High-energy ball milling process is a promising way to prepare BIT ceramics. After the preparation of the BIT, we doped it with the Multi-Walled Carbon Nanotubes which are properly obtained by a chemical vapour deposition (CVD), using nickel as a catalyst, as well as using acetilene at 720°C, and then proceeded with the dielectric and optical measurements.

关键词： Bi_(4)Ti_(3)O_(12) Ceramics Ferroelectric High-Energy Ball Milling Sintering Carbon Nanotubes MWNT

Periodic Modulation of Nonlinearity in a Fiber Bragg Grating:A Numerical Investigation

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Journal of Electromagnetic Analysis and Applications 2012年第2期4卷 53-59页

作者： antonio Francisco Gomes Furtado Filho Jose Rubens Rodrigues de Sousa Apiano Ferreira de Morais Neto Jose Wally Mendonca Menezes antonio sergio bezerra sombra Teleinformatics Engineering Department Federal University of CearaFortaleza-CeBrazil Telecommunications and Materials Science and Engineering Laboratory(LOCEM) Campus do PiciFortaleza-CEBrazil Department of Infrastructure Telecommu-nications Systems Specialist Laboratory and TeachingEastFederal Institute of CearaFortaleza CampusFortalezaBrazil

We present numerical studies on the switching characteristics of a fiber Bragg grating (FBG) with modulation in the third order nonlinear index of refraction along it’s length. The FBG is operating in a continuous wave regime (CW). This study was done taking into account the possible asymmetry brought by the non harmonic modulation of the nonlinearity, leading to different reflection and transmission characteristics, that depend on the direction of propagation along the modulated nonlinear FBG. This phenomenon may be useful for applications like an optical isolator. It was found that for a set of values of the modulation parameter, the FBG can exhibit multistable states. The numerical studies were obtained starting from the coupled-mode equations solved from the coupled-mode theory and simulated using the fourth-order Runge-Kutta method.

关键词： Bragg Gratings Nonlinearity Modulation Optical Bistability Nonlinear Switching

Optical Bistability in an Acousto-Optic Tunable Filter(AOTF)Operating with Short Optical Pulses

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Journal of Electromagnetic Analysis and Applications 2012年第3期4卷 112-117页

作者： Karlo David Alves Saboia Alex Sander Barros Queiroz Francisco Tiago Lima Cicero Saraiva Sobrinho Jose Wally Mendonca Menezes antonio sergio bezerra sombra Departamento de Fisica Laboratorio de Telecomunicacoes e Ciencia e Engenharia de Materiais(LOCEM)Universidade Federal do CearaFortalezaBrazil Faculdade de Educacao de Crateus-Universidade Estadual do Ceara CrateusBrazil Departamento de Teleinformatica Laboratorio Especialista em Sistemas de Telecomunicacoes e Ensino(LESTE)Instituto Federal do Ceara(IFCE)Campus FortalezaFortalezaBrazil

In this paper we report for the first time the presence of bistability in an acoustic-optic tunable filter (AOTF) operating with ultrashort (2 ps) optical light pulses. The results for the study of bistability has shown the dependence of the hysteresis curve with the product of the coupling constant (κ) by the length of the device (ξL) and the conversion power-coupling constant factor (G). The range of bistability varies significantly with both G and with κξL parameters. The variation of κξL directly increases the size of the range of bistability hysteresis while the increase in G causes the bistability to occur at low powers. The phenomenon of optical bistability (OB) is the object of increasing interest due to its possibilities for important device applications. A bistable device is a device with a capability to generate two different outputs for a given input and the physical requirements for this are an intensity-dependence refractive index and an optical feedback mechanism.

关键词： Bistability Acousto-Optic Tunable Filter

The Thermal Stability of (CaTiO₃)1-x (Cr_3/4Fe_5/4O₃)_x Ceramic Composites in the Microwave Region

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Materials Sciences and Applications 2016年第4期7卷 202-209页

作者： Francisco Nivaldo Aguiar Freire Manoel Roberval Pimentel Santos Hélio Henrique Barbosa Rocha Ana Fabiola Leite Almeida Selma Elaine Mazzetto antonio Jefferson Mangueira Sales antonio sergio bezerra sombra Department of Mechanical Engineering Federal University of Ceara Campus do Pici Fortaleza Brazil Western Para Federal University (UFOPA) Santarem Brazil Department of Organic and Inorganic Chemistry Federal University of Ceara Campus do Pici Fortaleza Brazil Department of Physics Federal University of Ceara Campus do Pici Fortaleza Brazil

The thermal stability, structural and dielectric properties of the (CaTiO3)1-x(Cr3/4Fe5/4O3)x ceramic composites with x = 0, 0.1, 0.5, 0.9 and 1 have been examined in microwave region. The samples were produced via the solid-state reaction. The orthorhombic structural phase of CaTiO3 and trigonal structural phase of Cr3/4Fe5/4O3 were confirmed by the X-Ray Powder Diffraction (XRPD). The XRPD patterns for composites reveal the quantities of each original phase present. The infrared spectra of the samples reinforce this structural verification indicating no or minimal occurrence of unwanted reactions. The first sample (x = 0) and last sample (x = 1) in this series exhibit the maximum and the minimum of the relative dielectric permittivity and values range from 140.1 to 8.3 respectively. The measured temperature coefficient of the matrix CaTiO3 was +921 ppm·℃-1 and for the matrix Cr3/4Fe5/4O3 was -56 ppm·℃-1. With the study of series of composites, it was possible to make a mathematical prediction for a composition reach the temperature coefficient near zero. The proposed ceramic has potential use as thermostable material in the microwave region and can be applied to resonators, low-noise amplifiers, filters, and so on.

关键词： Ceramics Composites Dielectric Properties

Analysis of the Performance of Optical Code-Division Multiple-Access System(OCDMA),Operating with Gold Codes under Nonlinear Effects

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Journal of Electromagnetic Analysis and Applications 2013年第2期5卷 49-57页

作者： Glendo de Freitas Guimaraes Agliberto Melo Bastos Alisson da Conceicao Ferreira Alex Sander Barros Queiroz Jose Wally Mendonca Menezes Jose Rubens Rodrigues de Sousa antonio sergio bezerra sombra Laboratorio de Telecomunicacoes e Ciencia e Engenharia dos Materiais(LOCEM) Departamento de FisicaUniversidade Federal do Ceara(UFC)FortalezaBrazil Laboratorio Especializado em Sistema de Telecomunicacoes e Ensino(LESTE) Departamento de TelematicaInstituto Federal do Ceara(IFCE)Campus FortalezaFortalezaBrazil Grupo de Fisica Aplicada e Docencia(GFAD) Instituto Federal do Ceara(IFCE)Campus SobralSobralBrazil Departamento de Engenharia de Teleinformatica(DETI) Centro de TecnologiaUniversidade Federal do Ceara(UFC)FortalezaBrazil Departamento de Engenharia de Energias Universidade da Integracao Internacional da Lusofonia Afro-Brasileira(UNILAB)RedencaoBrazil

A numerical simulation study of the performance of encoding and decoding of short optical pulse in OCDMA (Optical Code Division Multiple Access) systems under non-linear optical effects is presented. The performance of encoding and decoding short pulses is obtained through use of device FBG (fiber Bragg grating) where the codes are inserted through discrete jumps in the optical phase (±π). The multiuser interference is also the object of the present study, where a figure of merit (interference figure) is used to quantify the interference in multiuser auto and cross correlation. We evaluate the dependence of the multiuser interference for the coupling constant of FBG. Finally, the interference inserted in the autocorrelation due to nonlinear effects generated in the nonlinear switching of the coded pulse in a dual core nonlinear directional coupler is examined, where temporal broadening of pulses decoded is observed.

关键词： Fiber Bragg Grating Gold Code OCDMA All-Optical Digital Processing of Signals

Reproductive patterns in Araucaria araucana forests in the Andean range, Chile

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Ecological Processes 2024年第1期13卷 252-261页

作者： sergio Donoso Karen Pe?a-Rojas Claudia Espinoza Carolain Badaracco Rómulo Santelices-Moya antonio Cabrera-Ariza Mediterranean Forests Laboratory Faculty of Forestry and Nature Conservation Centro Secano Faculty of Agricultural and Forestry Sciences Universidad Católica del Maule Maule Advanced Studies Research Center Vice-Rector's Office for Research and Postgraduate Studies Catholic University of Maule

Background Araucaria araucana is a mast species that presents a high variability in annual cone production. Researchers have recorded synchronization events in cone production in different populations, which allows the seed production to be concentrated, reducing the percentage of seeds consumed by different animal *** We sampled three populations located in the Andes Mountains, Araucanía Region, Chile. In 2004 we began the collection of data on cone production, for which we installed permanent plots（1200 m2each） at each location. We identified and labeled each female tree in each plot to monitor its cone production. In 2012 we selected a total of 30 trees near the plots to evaluate the number of seeds per cone. In each February from 2012 to 2014 we selected two mature cones and covered them with a porous mesh for subsequent collection and storage in March. At the beginning of June, we counted and weighed the seeds, determining the average weight, the number of seeds per cone, the germination capacity（GC）, and the germination speed（GS）.Results Cone production was synchronous across the three locations. We observed significant differences among the locations and years evaluated. The cones had fewer seeds in 2013（high production） compared to those in 2012（low production）, but their weights were similar. In 2014 the cones produced smaller seeds in fewer quantities. The difference between the years 2013 and 2014 resulted from the high-energy expenditure in 2013. Regarding GC and GS, there were significant differences among the three locations（GC: F = 45.41, p < 0.01; GS: F = 96.08, p < 0.01）, where the highest values were observed in *** Both GC and GS are related to seed weight but not to the number of cones produced in a given year. These annual fluctuations in seed production are determining factors in the population dynamics of forest species. Our results allow a better understanding of the reproductive phenology of A. araucana and could hel

关键词： Seed weight Germination potential Masting species Sustainable use Dioecious species

Robust hybrid bismuth perovskites as potential photocatalysts for overall water splitting

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Nano Research 2024年第5期17卷 4593-4601页

作者： antonio J.Chacón-García Herme G.Baldovi Artem A.Babaryk antonio Rodríguez-Diéguez sergio Navalón Yolanda Pérez Hermenegildo García Patricia Horcajada Advanced Porous Materials Unit IMDEA Energy InstituteAvda.Ramón y Cajal 328935 MóstolesMadridSpain Departamento de Química Universitat Politècnica de València46022 ValènciaSpain Departamento Química Inorgánica Universidad de Granada1807GranadaSpain Departamento de Biología y Geología Física y Química Inorgánica.ESCET.Universidad Rey Juan Carlos28933 MóstolesMadridSpain Instituto de tecnología química CSIC-UPV Universitat Politècnica de València(UPV)46022Spain

Organic-inorganic hybrid perovskites have gained great attention as promising photocatalysts for hydrogen ***,due to their poor stability in water,the use of aqueous hydrohalic acid solutions is specifically required for an efficient hydrogen ***,three novel photoactive lead-free hybrid perovskites based on bismuth and triazolium cations(denoted as IEF-15,IEF-16,and IEF-17(IEF stands for IMDEA energy frameworks))were synthesized and fully characterized(structural,compositional,optical,etc.).Further,these solids were proposed as photocatalysts for the challenging gas phase overall water splitting(OWS)***,IEF-16 thin films exhibited a remarkable photocatalytic activity in both H_(2) and O_(2) evolution,as a consequence of its appropriate bandgap and energy-band alignment,achieving hydrogen evolution rates ofμmol·g_(H_(2))^(-)1846 and 360 after 24 h under ultraviolet-visible(UV-vis)irradiation or simulated solar irradiation,*** study additionally highlights the remarkable structural and photochemical stability of IEF-16 under different operational conditions(*** volume,irradiation and temperature),paving the way for green hydrogen production from OWS using perovskite-based photocatalysts.

关键词： bismuth-based hybrid perovskites thin films photocatalysis overall water splitting green hydrogen

Spermotrend Improves Semen Quality and Infertility in Men with Varicocele —Spermotrend and Male Infertility

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Advances in Reproductive Sciences 2024年第2期12卷 83-97页

作者： Melida Aguilar Chamorro sergio antonio Vargas Collado David Marquez Soriano Clinica Seniors Managua Nicaragua Scientific Department Catalysis S.L. Madrid Spain

Background: Infertility affects 8% - 12% of couples globally, with approximately half of the cases reported in males. Oxidative stress is a common factor increased in the varicocele condition and particularly affects spermatozoa, due to their sensitivity to oxidative signals and testicular hypotrophy. The objective of this clinical trial is to study the effectiveness of Spermotrend in the improvement of sperm parameters in male infertility. Methods: A total of 170 males aged > 18 years with a diagnosis of infertility and varicocele were consecutively enrolled in a Phase II, open-label clinical trial. Spermotrend was administered 1 capsule (450 mg) orally every 8 hours for 6 months and was evaluated through semen analysis at 4 and 6 months of follow-up. Results: The trial results show a significant improvement following the administration of Spermotrend over 6 months in sperm concentration (44.1% at baseline vs. 64.1% at 6 months), sperm survival (28.2% with sperm survival ≥ 2 hours vs.56.5%), normalization of sperm morphology (31.2% vs. 72.9%). Varicocele condition decreased in all patients and, by the end of the study, 55.3% of patients had normal venous flow and dilation. Only 5.9% of the patients showed grade 2 varicocele at the end of the study, while 38.8% showed grade 1 varicocele, with no patients showing grade 3 varicocele. Regarding testicular hypotrophy, 90.6% of the patients completed the study with normalized testicular volume by recovering normal venous flow. Conclusion: A short-term course of Spermotrend may significantly improve sperm parameters associated with male infertility. Clinical Trial Registration: The clinical trial protocol was registered in the international clinical trial registry, ***, with the code: NCT05222841 on 15/06/2021.

关键词： Antioxidants Dietary Supplementation Male Infertility Spermatogenesis Varicocele Pygeum africanum

Assessment of earthquake location uncertainties for the design of local seismic networks

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Earthquake Science 2024年第5期37卷 415-433页

作者： antonio Fuggi Simone Re Giorgio Tango sergio Del Gaudio Alessandro Brovelli Giorgio Cassiani Isamgeo Italia S.r.l. Gallarate 21013Italy STOGIT S.p.A. UnitàGiacimentiCrema 26013Italy Dipartimento di Geoscienze Universitàdegli Studi di PadovaPadova 35131Italy

The ability to estimate earthquake source locations,along with the appraisal of relevant uncertainties,is paramount in monitoring both natural and human-induced *** this purpose,a monitoring network must be designed to minimize the location errors introduced by geometrically unbalanced *** this study,we first review different sources of errors relevant to the localization of seismic events,how they propagate through localization algorithms,and their impact on *** then propose a quantitative method,based on a Monte Carlo approach,to estimate the uncertainty in earthquake locations that is suited to the design,optimization,and assessment of the performance of a local seismic monitoring *** illustrate the performance of the proposed approach,we analyzed the distribution of the localization uncertainties and their related dispersion for a highly dense grid of theoretical hypocenters in both the horizontal and vertical directions using an actual monitoring network *** results expand,quantitatively,the qualitative indications derived from purely geometrical parameters(azimuthal gap(AG))and classical detectability *** proposed method enables the systematic design,optimization,and evaluation of local seismic monitoring networks,enhancing monitoring accuracy in areas proximal to hydrocarbon production,geothermal fields,underground natural gas storage,and other subsurface *** approach aids in the accurate estimation of earthquake source locations and their associated uncertainties,which are crucial for assessing and mitigating seismic risks,thereby enabling the implementation of proactive measures to minimize potential *** an operational perspective,reliably estimating location accuracy is crucial for evaluating the position of seismogenic sources and assessing possible links between well activities and the onset of seismicity.

关键词： network design earthquake localization detectability localization uncertainties local seismic network

Multi-omic study to unmask genes involved in prostate cancer development in amulti-case family

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Cancer Communications 2024年第3期44卷 443-447页

作者： Lucia Chica-Redecillas sergio Cuenca-Lopez Eduardo Andres-Leon Laura Carmen Terron-Camero Blanca Cano-Gutierrez Jose Manuel Cozar Jose antonio Lorente Fernando Vazquez-Alonso Luis Javier Martinez-Gonzalez Maria Jesus Alvarez-Cubero GENYO Centre for Genomics and Oncological ResearchPfizerUniversity of GranadaAndalusian Regional GovernmentPTS GranadaGranadaGranadaSpain Department of Biochemistry Molecular Biology III and ImmunologyFaculty of MedicineUniversity of GranadaPTS GranadaGranadaGranadaSpain Bioinformatics Unit Institute of Parasitology and Biomedicine“López-Neyra”Spanish National Research CouncilGranadaGranadaSpain Nursery Service.University Hospital Clínico San Cecilio GranadaGranadaSpain Urology Department University Hospital Virgen de las NievesGranadaGranadaSpain Legal Medicine and Toxicology Department Faculty of MedicineUniversity of GranadaPTS GranadaGranadaGranadaSpain Ibs Biosanitary Research InstituteGranadaGranadaSpain

Dear Editor,Hereditary prostate cancer(PC)comprises 5%-10%of all PC *** increased risk of PC in menwith a family his-tory of the disease is well known and is commonly caused by germline mutations,leading to clinical guidelines men-tioning various genes for identifying high-risk ***,the complex inheritance patterns involvingmul-tiple single nucleotide polymorphisms(SNPs)make it a genetically heterogeneous disease,with genetic testing still in its early stages.

关键词： cancer clinical cases