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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

Glial regenerative response in the imaginal discs of Drosophila melanogaster

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Neural Regeneration Research 2023年第1期18卷 109-110页

作者： sergio B.Velarde antonio Baonza Centro de Biología Molecular“Severo Ochoa” CSIC/UAMMadridSpain

Glial cells play a key role during nervous system development and actively participate in all the cellular processes involved in maintaining its structural robustness and functional *** response to neuronal damage,glial cells proliferate,migrate to the injured region and change their morphology,function,and behavior(Gallo and Deneen,2014;Kato et al.,2018).This glial regenerative response is associated with the repairing function of these cells and is found across species,suggesting that it may reflect a common underlying genetic mechanism(Kato et al.,2018).

关键词： damage migrate

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Rhynchophorus ferrugineus attack affects a group of compounds rather than rearranging Phoenix canariensis metabolic pathways

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Journal of Integrative Plant Biology 2016年第4期58卷 388-396页

作者： antonio Giovino Federico Martinelli sergio Saia Consiglio per la Ricerca in Agricoltura e l'analisi dell'economia agraria(CREA) Unita di ricerca per il recupero e la valorizzazione delle Specie Floricole Mediterranee(CREA-SFM)90011 Bagheria(PA)Italy Dipartimento di Scienze Agrarie e Forestali(SAF) University of PalermoViale delle ScienzeEdif.490128 PalermoItaly Istituto Euromediterraneo di Scienza e Tecnologia(IEMEST) Via E.Amari 12390139 PalermoItaly

The red palm weevil（RPW; Rhynchophorus ferrugineus） is spreading worldwide and severely harming many palm species. However, most studies on RPW focused on insect biology, and little information is available about the plant response to the attack. In the present experiment, we used metabolomics to study the alteration of the leaf metabolome of Phoenix canariensis at initial（1^（st） stage） or advanced（2^（nd） stage）attack by RPW compared with healthy（unattacked） *** leaf metabolome significantly varied among treatments. At the 1^（st） stage of attack, plants showed a reprogramming of carbohydrate and organic acid metabolism; in contrast, peptides and lipid metabolic pathways underwent more changes during the 2^（nd） than 1^（st） stage of attack. Enrichment metabolomics analysis indicated that RPW attack mostly affected a particular group of compounds rather than rearranging plant metabolic pathways. Some compounds selectively affected during the 1^（st） rather than 2^（nd） stage（e.g. phenylalanine; tryptophan; cellobiose;xylose; quinate; xylonite; idonate; and iso-threonate; cellobiotol and arbutine） are upstream events in the phenylpropanoid,terpenoid and alkaloid biosynthesis. These compounds could be designated as potential markers of initial RPW attack. However,further investigation is needed to determine efficient early screening methods of RPW attack based on the concentrations of these molecules.

关键词： Early detection Mediterranean environment metabolomics palms plant borer

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Avian malaria,haematocrit,and body condition in invasive wetland passerines settled in southwestern Spain

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Avian Research 2023年第1期14卷 99-107页

作者： Jaime Muriel Luz Garcia-Longoria sergio Magallanes Juan antonio Ortiz Alfonso Marzal Instituto de Investigación en Recursos Cinegéticos(IREC) CSIC-UCLM-JCCMRonda de Toledo 1213005Ciudad RealSpain Universidad de Extremadura Facultad de BiologíaDepartamento de AnatomíaBiología Celular y Zoología Avenida de Elvas s/n06006BadajozSpain Estación Biológica de Donana(EBD-CSIC) Departamento de Ecología de los HumedalesAvda.Américo Vespucio 2641092SevillaSpain Hirundo Bird Ringing Group BadajozSpain Grupo de Investigaciones en Fauna Silvestre Universidad Nacional de San MartínJr.Maynas177722021TarapotoPeru

Avian malaria and related haemosporidian parasites can negatively impact fitness in many *** on the malaria infection and its physiological costs on their avian hosts is heavily skewed toward native passerines,with exotic species ***,introduced species may carry on and spread new pathogens to native species,and play a role on parasite transmission cycle in invaded bird communities as pathogen ***,we molecularly assess the prevalence and diversity of haemosporidian parasites in three introduced wetland passerines(the Red Avadavat Amandava amandava,the Yellow-crowned Bishop Euplectes afer,and the Common Waxbill Estrilda astrild)captured during the same season in southwestern *** also explored the relation between parasite infection,body condition,haematocrit,and uropygial gland *** detected an overall parasite prevalence of 3.55%,where Common Waxbills showed higher prevalence(6.94%)than Red Avadavats(1.51%).None Yellow-crowned Bishops were infected with *** 60%of infections were caused by Leucocytozoon,and about 40%by *** identified four unique lineages of Plasmodium and three of ***,91%of the identified host-parasite interactions represented new host records for these haemosporidian *** infection was not related to body condition,haematocrit,and uropygial gland volume of the wetland *** values varied seasonally among bird ***,haematocrit was positively related to body condition in the Yellow-crowned Bishops,but not in the other *** Avadavats had higher haematocrit levels than Yellow-crowned Bishops,whereas Common Waxbills showed the lower haematocrit *** uropygial gland volume was positively correlated with body condition in all bird *** Waxbills showed higher uropygial gland volumes related to their body size than birds from other two *** outcomes highlight the importance of e

关键词： Avian malaria Exotic species Introduced birds Leucocytozoon Plasmodium Uropygial gland

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Small intestine bacterial overgrowth and irritable bowel syndrome-related symptoms:Experience with Rifaximin

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World Journal of Gastroenterology 2009年第21期15卷 2628-2631页

作者： sergio Peralta Claudia Cottone Tiziana Doveri Piero Luigi Almasio antonio Craxi Operative Unit of Gastroenterology and Hepatology

AIM： TO estimate the prevalence of small intestinal bacterial overgrowth （SIBO） in our geographical area （Western Sicily, Italy） by means of an observational study, and to gather information on the use of locally active, non-absorbable antibiotics for treatment of SIBO.METHODS： Our survey included 115 patients fulfilling the Rome II criteria for diagnosis of irritable bowel syndrome （IBS）; a total of 97 patients accepted to perform a breath test with lactulose （BTLact）, and those who had a positive test, received Rifaximin （Normix , Alfa Wassermann） 1200 mg/d for 7 d; 3 wk after the end of treatment, the BTLact was repeated.RESULTS： Based on the BTLact results, SIBO was present in about 56% of IBS patients, and it was responsible for some IBS-related symptoms, such as abdominal bloating and discomfort, and diarrhoea. 1-wk treatment with Rifaximin turned the BTLact to negative in about 50% of patients and significantly reduced the symptoms, especially in those patients with an alternated constipation/diarrhoea-variant IBS. CONCLUSION： SIBO should be always suspected in patients with IBS, and a differential diagnosis is done by means of a ＂breath test＂. Rifaximin may represent a valid approach to the treatment of SIBO.

关键词： Rifaximin Small intestinal bacterialovergrowth Irritable bowel syndrome Locally nonabsorbable antibiotics

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