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International audience; The development of simple and reproducible synthesis techniques for obtaining one-dimensional semiconducting nanostructures is essential for the advancement of gas sensor devices. We report a facile and versatile approach for the in-situ growth of vertically oriented hematite nanorods to be applied as a resistive ozone gas sensor. The α-Fe2O3 nanorods were grown via a hydrothermal treatment directly onto an Al2O3 substrate with interdigitated Pt electrodes, thus facilitating the integration of nanorods into the sensing platform. At 150 °C, the gas-sensing experiments revealed a good sensitivity of these nanorods to different ozone concentrations (10 to 570 ppb), besides a fast response time and repeatable response–recovery cycles. The present study offers a promising way for designing high-performance gas sensors based on hematite nanorods.

Made available in DSpace on 2021-06-25T11:44:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-07 LNLS, Campinas, SP, Brazil Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) In this study, we report the potential of ethylenediamine (En) in the modification of the morphological, structural, optical and catalytic properties of alpha-Ag2WO4 crystals decorated with Ag nanoparticles (Ag NPs). Experimental techniques were used to characterize the as-synthesized samples such as X-ray diffraction, Raman, electron microscopy, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and photoluminescence spectroscopy. The results confirmed the efficiency of En in the decoration with the formation of Ag/alpha-Ag2WO4 crystals and also the modification of alpha-Ag2WO4 morphology that indicated its influence on the crystal growth mechanism via self-assembly and Ostwald ripening. En affects the degree of order/disorder of the crystalline structures in long and short-ranges. In addition, photoluminescence measurements revealed a blue shift of the optical emission caused by a reduction of oxygen vacancies and an increase in structural disorder due to the En concentration used in the synthesis processes. Regarding the photocatalysis experiments, the reduction in oxygen vacancies also caused a decrease in the photoactivity of alpha-Ag2WO4 against the rhodamine B dye, thus confirming the relevance of oxygen vacancies for the development of alpha-Ag2WO4 photocatalysts. Univ Fed Sao Carlos, Ctr Dev Funct Mat, Rod Washington Luiz,Km 235, BR-13565904 Sao Carlos, SP, Brazil Sao Paulo State Univ, Interdisciplinary Lab Ceram Studies, BR-14800900 Araraquara, SP, Brazil Univ Estadual Campinas, Inst Chem, Dept Phys Chem, BR-13083970 Campinas, SP, Brazil Univ Fed Sao Carlos, Dept Phys, Rod Washington Luiz,Km 235, BR-13565905 Sao Carlos, SP, Brazil Sao Paulo State Univ, Interdisciplinary Lab Ceram Studies, BR-14800900 Araraquara, SP, Brazil LNLS, Campinas, SP, Brazil: XAFS2-20180338 CNPq: 443733/2018-0 FAPESP: 2013/07296-2 FAPESP: 2017/12437-5 CAPES: 001

International audience; Chemiresistors are highly important for monitoring and detection of harmful gases produced from industrial processes and vehicle emissions. We report herein an experimental investigation of the gas-sensing properties of Zn0.95Co0.05O thin film deposited by spray pyrolysis technique. The X-ray photoelectron spectroscopy indicated the presence of Co2+ ions into de ZnO lattice. The gas-sensing measurements revealed the sensitivity of Zn0.95Co0.05O film towards ozone gas in a wide range of concentrations from 20 to 1040 ppb, exhibiting good repeatability and total reversibility after consecutive exposures. Selectivity towards ozone is observed in comparison to NO2, NH3, and CO gases even at low levels. This manuscript reports the effectiveness of spray-pyrolysis method for obtaining nanostructured Zn1-xCoxO thin films for practical applications as an ozone gas sensor.

CO2 electrochemical reduction reaction (CO2RR) is an attractive strategy for closing the anthropogenic carbon cycle and storing intermittent renewable energy. Tin-based electrocatalysts exhibit remarkable properties for reducing CO2 into HCOOH. However, the effects of morphology and oxidation state of tin-based electrocatalysts on the performance of CO2 reduction have not been well-described. We evaluate the oxidation state and particle size of SnOx for CO2 reduction. SnOx was effective for converting CO2 into formic acid, reaching a maximum selectivity of 69%. The SnO exhibited high activity for CO2RR compared to SnO2 electrocatalysts. A pre-reduction step of a SnO2 electrocatalyst increased its CO2 reduction performance, confirming that Sn2+ is more active than Sn4+ sites. The microsized SnO2 is more effective for converting CO2 into formic acid than nanosized SnO2, likely due to the impurities of nanosized SnO2. We illuminated the role played by both SnOx particle size and oxidation state on CO2RR performance. Graphic abstract

International audience; Over the past fifty years, gas sensors based on metal semiconducting oxides (MOXs) have drawn attention due to their performance in detecting various gases. Thus, we report herein on a BTEX gases sensor based on hematite (α-Fe2O3) microrhombuses synthesized via the hydrothermal method. X-ray diffraction and X-ray absorption spectroscopy analyses indicated the presence of a pristine hematite phase after hydrothermal treatment. Electron microscopy analyses revealed that the hematite sample consists of single-crystals with a rhombus-like shape and an average size of 140 nm. Electrical measurements pointed out that hematite microrhombuses were sensitive towards sub-ppm BTEX levels, in which the minimum detected level was 3 ppb and the long-term stability was 1 month. The results presented here demonstrate the potential of hematite microrhombuses as a sensing material to manufacture BTEX gas sensor devices.

Made available in DSpace on 2018-11-29T12:10:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-06-05 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Brazilian Nanotechnology National Laboratory Brazilian Laboratory of Synchrotron Radiation (LNLS) Generalitat Valenciana, Ministerio de Economia y Competitividad Programa de Cooperacion Cientifica con Iberoamerica (Brazil), Ministerio de Educacion This paper consists of an experimental investigation on the effects of annealing temperature on the structural, surface and ozone gas-sensing properties of CuWO4 nanoparticles prepared via a sono-chemical route. X-ray diffraction patterns and X-ray absorption near-edge structure spectroscopy revealed that both long-and short-order structures increase with the annealing temperature. Electrical resistance measurements indicated that CuWO4 samples were sensitive in the range of 15-1400 ppb, exhibiting a good reversibility and repeatability. The enhancement of the ozone gas-sensing properties was attributed to the reduction of hydroxyl species and the improvement of the crystallization degree. This study provides a versatile strategy for obtaining CuWO4 nanoparticles for practical applications as an ozone gas sensor. (C) 2018 Elsevier B.V. All rights reserved. Sao Paulo State Univ, Inst Chem, POB 355, BR-14801907 Araraquara, SP, Brazil Aix Marseille Univ, CNRS UMR 7334 IM2NP, FS St Jerome S152, F-13397 Marseille, France Univ Estadual Piaui, PPGQ CCN, POB 381, BR-64002150 Teresina, PI, Brazil Univ Fed Sao Carlos, Dept Phys, Lab Nanostruct Multifunct Mat, BR-13565905 Sao Carlos, SP, Brazil Jaume I Univ, Dept Chem & Phys, Castellon De La Plana, Spain Sao Paulo State Univ, Inst Chem, POB 355, BR-14801907 Araraquara, SP, Brazil FAPESP: 2013/07296-2 FAPESP: 2017/10313-7 FAPESP: 2017/12437-5 CNPq: 310863/ 2014-7 CNPq: 434266/2016-7 Brazilian Nanotechnology National Laboratory: LMF-18580 Brazilian Laboratory of Synchrotron Radiation (LNLS): D04B-XAFS111883

Made available in DSpace on 2018-11-26T17:44:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The need to improve the sensitivity, selectivity and stability of ozone gas sensors capable of monitoring the environment to prevent hazard to humans has sparked research on binary metal oxides. Here we report on a novel ozone gas sensor made with ca. 0.5 mu m yolk-shelled ZnCo2O4 microstructures synthesized via an eco-friendly, co-precipitation method and subsequent annealing. With these ZnCo2O4 microspheres, ozone concentrations down to 80 parts per billion (ppb) could be detected with a.c. and d.c. electrical measurements. The sensor worked within a wide range of ozone concentrations, from 80 to 890 ppb, being also selective to ozone compared to CO, NH3 and NO2. The high performance could be attributed to the large surface area to volume ratio inherent in yolk-shell structures. Indeed, ozone molecules adsorbed on the ZnCo2O4 surface create a layer of holes that affect the conductivity, as in a p-type semiconductor. Since this mechanism of detection is generic, ZnCo2O4 microspheres can be further used in other environment monitoring devices. (c) 2017 Elsevier B.V. All rights reserved. Univ Sao Paulo, Sao Carlos Inst Phys, CP 369, BR-13560970 Sao Carlos, SP, Brazil Univ Calif Berkeley, Dept Mech Engn, Berkeley, CA 94720 USA Univ Fed Sao Carlos, Dept Phys, Rodovia Washington Luis Km 235, BR-13565905 Sao Carlos, SP, Brazil Myongji Univ, Dept Energy Sci & Technol, Yongin, South Korea Sao Paulo State Univ, Inst Chem, Dept Phys Chem, POB 355, BR-14800900 Araraquara, SP, Brazil Sao Paulo State Univ, Inst Chem, Dept Phys Chem, POB 355, BR-14800900 Araraquara, SP, Brazil FAPESP: 2012/15543-7 FAPESP: 2013/14262-7 FAPESP: 2013/07296-2 FAPESP: 2014/23546-1 FAPESP: 2016/23474-6

This manuscript addresses an experimental and theoretical investigation regarding the ozone (O3) gas-sensing properties of hematite microrhombuses obtained via the hydrothermal method. Gas-sensing experiments showed the sensitivity of the microrhombuses towards O3 gas from 12 ppb (parts-per-billion), presenting total recovery and a long-term stability of 4 months. Theoretical calculations revealed that the surfaces play an important role in the adsorption/desorption processes. Moreover, it was found that the presence of (1 0 4) surfaces is favorable to the high sensitivity towards O3 molecules, confirming the experimental results. These results allowed us to better understand the morphological changes and directly relate the sensing performance of hematite microcrystals at different exposed surfaces.

Made available in DSpace on 2018-11-26T15:44:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-11-30 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Financiadora de Estudos e Projetos (FINEP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) Reduced graphene oxide-zinc oxide (rGO-ZnO) nanocomposites were successfully synthesized using a facile microwave-hydrothermal method under mild conditions, and their electrocatalytic properties towards O-2 evolution were investigated. The microwave radiation played an important role in obtainment of well dispersed ZnO nanoparticles directly on reduced graphene oxide sheets without any additional reducing reagents or passivation agent. X-ray diffraction (XRD), Raman and infrared spectroscopies indicated the reduction of GO as well as the successful synthesis of rGO-ZnO nanocomposites. The chemical states of the samples were shown by XPS analyses. Due to the synergic effect, the resulting nanocomposites exhibited high electronic interaction between ZnO and rGO sheets, which improved the electrocatalytic oxidation of water with low onset potential of 0.48 V (vs. Ag/AgCl) in neutral pH and long-term stability, with high current density during electrolysis. The overpotential for water oxidation decreased in alkaline pH, suggesting useful insight on the catalytic mechanism for O-2 evolution. (C) 2017 Elsevier B.V. All rights reserved. Univ Fed Uberlandia, Inst Quim, BR-38400902 Uberlandia, MG, Brazil Univ Estadual Paulista, LIEC, Inst Quim, BR-14800900 Araraquara, SP, Brazil Univ Fed Sao Carlos, Dept Fis, BR-13565905 Sao Carlos, SP, Brazil Univ Fed Sao Carlos, Dept Quim, LIEC, BR-13565905 Sao Carlos, SP, Brazil Univ Estadual Paulista, LIEC, Inst Quim, BR-14800900 Araraquara, SP, Brazil FAPEMIG: APQ-00988-13 FAPEMIG: CEX-RED-00010-14 FAPEMIG: APQ-00330-14

Made available in DSpace on 2020-12-10T17:37:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-09 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) LNLS, Campinas, SP, Brazil White light photoluminescent materials can overcome many problems due to an intrinsic color balance, in addition to reducing the cost for application in emitting components and electronic devices. In this sense, to observe this phenomenon of photoluminescence, variations in the synthesis time at low temperatures were carried out, which also influenced the degree of structural order/disorder of strontium vanadate (Sr10V6O2.5, SVO). The microwave-assisted hydrothermal route allowed us to evaluate the structural and morphological evolution of the SVO compound. Furthermore, this paper discusses how van der Waals forces influence the morphological evolution of a semiconductor as a function of orientation, induction, and dispersion interactions. The experimental study combined with theoretical approaches provided information about the structure and electronic properties of SVO. From the experimental data and theoretical analysis, we propose, for the first time, that the unit cell of the SVO structure is composed of three distorted [SrOx] (x = 6, 7, and 9) and two distorted [VO4] clusters. Photoluminescence measurements revealed an efficient broadband emission, and the conversion of ultraviolet light excitation into visible light was observed. The emission chromaticity showed that the structural disorders of the [SrOx] and [VO4] clusters present the possibility of change in the Commission Internationale de l'Eclairage emission color. Univ Fed Sao Carlos, CDMF UFSCar, BR-13565905 Sao Carlos, SP, Brazil Univ Estadual Campinas, Inst Chem, BR-13083970 Campinas, SP, Brazil Univ Estadual Sudeste Bahia, UESB, BR-45700000 Itapetinga, BA, Brazil Univ Fed Sao Carlos, Dept Fis, BR-13565905 Sao Carlos, SP, Brazil Univ Estadual Paulista, Fac Ciencias, Grp Modelagem & Simulacoes Mol, BR-17033360 Bauru, SP, Brazil IFSC Univ Sao Paulo, BR-13560970 Sao Carlos, SP, Brazil Univ Estadual Paulista, Fac Ciencias, Grp Modelagem & Simulacoes Mol, BR-17033360 Bauru, SP, Brazil CAPES: 001 FAPESP: 2013/07296-2 FAPESP: 2019/01732-1 FAPESP: 2016/23891-6 LNLS, Campinas, SP, Brazil: XAFS2-20180338

In this contribution, we present an experimental and theoretical investigation of the role of counter-ions in the crystal morphology, surface structure, and photocatalytic activity of hierarchical ZnO nanostructures. The effect of zinc precursor (nitrate, acetate and, sulfate) along the synthesis of ZnO nanostructures grown directly onto a substrate by means of a simple hydrothermal method was analyzed in detail. Scanning electron microscopy images showed a preferential growth of ZnO nanostructures along the c-axis, with a slight reduction in the orientation depending on the choice of the Zn source. Theoretical calculations based on the Wulff theory allowed us to better understand the morphological changes and directly relate the photocatalytic performance at the different exposed surfaces of the as-observed crystal shapes. Our results showed that photocatalytic activities in the discoloration of organic dyes became superior for hierarchical ZnO nanostructures obtained from zinc nitrate. This finding was explained by X-ray photoelectron and photoluminescence spectroscopies, which revealed that in addition to, the attached counter-ions and the abundance of carboxylate groups and organic residuals on ZnO surfaces, the presence of surface defects are determinant to enhance the photocatalytic performance of the material.

Made available in DSpace on 2018-12-11T17:17:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-04-01 The donkey jack sex glands are larger than stallions, responsible for producing most part of seminal plasma and the second fraction of ejaculate, along with epididymis tail. Plugged ampullae occur by sperm accumulation obstructing the lumen, inducing decrease in sperm quality and may cause azoospermia. In this study, a Pêga breed donkey jack, aging 4 years, was evaluated for breeding soundness evaluation due to a sudden decrease in semen parameters and low fertility rates. Palpation, measurements, and ultrasound examinations of testicles were normal; however, rectal palpation revealed increased volume of ampullae and deferent duct, and the transrectal ultrasonography revealed distended ampullae with hyperechogenic material in the ampullae lumen. After ampullae massage, the semen was collected with artificial vagina for evaluation, resulting in high concentrated semen (1.46 × 109 spermatozoa/mL) with low motility (5%), 14% of major defects, and 57% of minor defects. Plugged ampullae were suggested, and the treatment was performed by ampullae massage per rectum and three consecutive semen collections associated with the parenteral use of oxytocin 20 IU iv, aiming to discharge the semen accumulation. Daily regimen of semen collection was recommended during 10 days, and after this time, semen was collected at least three times a week. The semen parameters restored to normal (80% motility) after 30 days. The donkey jack returned to the breeding season with a regimen of 3 days a week of semen collection. Department of Animal Reproduction and Veterinary Radiology College of Veterinary Medicine and Animal Science Univ Estadual Paulista (UNESP) Department of Animal Reproduction and Veterinary Radiology College of Veterinary Medicine and Animal Science Univ Estadual Paulista (UNESP)

Made available in DSpace on 2022-04-28T19:28:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-04-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Generalitat Valenciana Ministerio de Economía y Competitividad Universitat Jaume I Laboratório Nacional de Luz Síncrotron To achieve a stable material capable of white-light emission, we fabricated Ca10V6O25 by both co-precipitation (CP) and microwave-assisted hydrothermal (MAH) methods at different temperatures. The effects of structural disorder at a short-range (Raman spectra), medium-range (UV–vis spectra), and long-range (X-ray diffraction) on the material structure and its effect on optical properties were investigated. Both CP and the MAH methods were efficient for obtaining pure Ca10V6O25 material with different morphologies. Significant changes in morphology and degree of structural order and disorder were found to affect the photoluminescence (PL) properties. All samples exhibited a broadband PL spectrum, characteristic associated to charge transfer processes of the [VO4]3- group, as well as transitions that occurred in the energy levels located within the band gap. The samples obtained by the MAH method at temperatures of 100 °C and 120 °C exhibited a lower structural disorder (at long- and short-ranges), the CIE chromaticity coordinates were located in the white region, MAH100 (x = 0.311 and y = 0.348) and MAH120 (x = 0.350 and y = 0.368). Furthermore, we conducted a detailed study of temperature dependence of PL spectra. All samples displayed decreased luminescence intensity as temperatures increased and low values of activation energy (approximately 2 meV). Finally, the as-synthetized Ca10V6O25 material has interesting properties for possible applications as a white-emitting phosphor under ultraviolet excitation. CDMF-UFSCar Universidade Federal de São Carlos, P.O. Box 676 Departamento de Física Universidade Federal de São Carlos Rod. Washington Luiz, km 235, CP 676 High Fields Magnetic Laboratory Radboud University, Toernooiveld 7 Departamento de Química Física i Analítica Universitat Jaume I Grupo de Modelagem e Simulações Moleculares Faculdade de Ciências Universidade Estadual de São Paulo Grupo de Modelagem e Simulações Moleculares Faculdade de Ciências Universidade Estadual de São Paulo CAPES: 001 CNPq: 166281/2017–4 FAPESP: 2018/01808–5 Generalitat Valenciana: ACOMP/2015/1202 Ministerio de Economía y Competitividad: CTQ2015-65207-P Generalitat Valenciana: PrometeoII/2014/022 Universitat Jaume I: UJI-B2016-25 Laboratório Nacional de Luz Síncrotron: XAFS2-20180338

Material processing has become essential for the proper control, tuning and consequent application of the properties of micro/nanoparticles. In this case, we report herein the capability of the microwave-assisted hydrothermal (MAH) method to prepare the SrTiO3 compound, as a case study of inorganic compounds. Analyses conducted by X-ray diffraction, X-ray photoelectron and X-ray absorption spectroscopies confirmed that the MAH route enables the formation of pristine SrTiO3. The results indicated that the combination of thermal and non-thermal effects during the MAH treatment provides ideal conditions for an efficient and rapid synthesis of pristine SrTiO3 mesocrystals. Scanning electron microscopy images revealed a cube-like morphology (of ca. 1 μm) formed via a self-assembly process, influenced by the MAH time. Additionally, photoluminescence measurements revealed a broad blue emission related to intrinsic defects, which decreased with the MAH synthesis time.

Over the last decades, there has been considerable interest in the synthesis of one-dimensional (1D) metal oxide nanostructures that can be used in gas sensor devices. Heterostructures, obtained by a combination of different semiconductor nanomaterials with different band energies, have been extensively studied in order to enhance their gas-sensing performance. In this context, our present study focuses on the investigation of chemiresistive-sensing capabilities of a combination of TiO2 nanoparticles and V2O5 nanowires obtained via hydrothermal treatment of the peroxo-metal complex. The formation of V2O5/TiO2 heterostructures was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) measurements. This study also proposes an efficient approach to produce 1D V2O5/TiO2 heterostructures with a good range of detection (0.09–1.25 ppm) and remarkable ozone-sensing properties related to repeatability and selectivity., The authors gratefully acknowledge the financial support of the Brazilian research funding agencies FAPESP (under grant number FAPEP 2013/17639-4, 2013/07296-2, 17/18649-4, and 2017/12437-5), CNPq (311463/2017-7), and CAPES (Financial Code 001). Transmission electron microscopy (TEM-21464) and X-ray photoelectron spectroscopy (XPS20607 and XPS-21082) were performed at the LME/ LNNano/CNPEM. The electrodes used for the gas-sensing experiments were fabricated in the Laboratory of Microfabrication at the LNNano/CNPEM (Projects LMF-18580). The STEM-EELS and HRTEM measurements were performed in the Advanced Microscopy Laboratory (LMA) at the Institute of Nanoscience of Aragon (INA), University of Zaragoza (Spain). R.A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MAT2016-79776-P) and the Government of Aragon through projct DGA E13_17R (FEDER, EU).

Two kinds of flexible ozone (O3) sensors were obtained by placing pristine ZnO nanorods and gold-modified ZnO nanorods (NRs) on a bi-axially oriented poly(ethylene terephthalate) substrate. The chemiresistive sensor is operated at typically 1 V at room temperature under the UV-light illumination. The ZnO nanorods were prepared via a hydrothermal route and have a highly crystalline wurtzite structure, with diameters ranging between 70 and 300 nm and a length varying from 1 to 3 μm. The ZnO NRs were then coated with a ca. 10 nm gold layer whose presence was confirmed with microscopy analysis. This sensor is found to be superior to detect ozone at a room temperature. Typical figures of merit include (a) a sensor response of 108 at 30 ppb ozone for gold-modified ZnO NRs, and (b) a linear range that extends from 30 to 570 ppb. The sensor is stable, reproducible and selective for O3 compared to other oxidizing and reducing gases. The enhanced performance induced by the modification of ZnO nanorods with thin layer of gold is attributed to the increased reaction kinetics compared to pristine ZnO NRs. The sensing mechanism is assumed to be based on the formation of a nano-Schottky type barrier junction at the interface between gold and ZnO.

Made available in DSpace on 2019-10-06T15:22:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-02-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Zinc sulfide (ZnS) is a II–VI inorganic semiconductor material and has received remarkable attention because of fundamental physical properties, versatility, nontoxicity, chemical stability and has been widely applied to make numerous optical devices as phosphor material. As a wide band gap semiconductor, ZnS can easily host different metal ions as luminescent center to improve or modify its structural and optical performances such as Cu atoms. In this paper, ZnS:Cu nanoparticles were synthesized by solvothermal method and the photoluminescence and the structural at long- and local-range properties were characterized. According to X-ray diffraction results, ZnS sample crystallizes with the cubic zinc blende structure (F-43m space group) without spurious phases. Images from transmission electron microscope depict the morphology of ZnS particles as round shape and average size value lower than 5 nm. Theoretical and experimental X-ray absorption near edge structure (XANES) spectra at Zn K-edge suggest the incorporation of Cu atoms into the ZnS host and indicate the occurrence of Zn and S vacancies, which are confirmed by extended X-ray absorption fine structure (EXAFS) fit results. These native defects are related to a red-shift observed in the peak emission of photoluminescence (PL) spectrum for ZnS sample, which is centered at ~ 504 nm. An emission in orange-red region is observed as Cu is incorporated in the ZnS host matrix that is attributed to the transition from the 4T1 level to the 6A1 level. Moreover, the intensity of the emissions due to zinc vacancies and interstitial zinc in the deconvoluted PL spectrum is in accordance with results determined in X-ray absorption spectroscopy characterization. Institute of Geosciences and Exact Sciences São Paulo State University Unesp Department of Physics Federal University of São Carlos UFSCar São Carlos Institute of Physics University of São Paulo USP LIEC Department of Chemistry Federal University of São Carlos UFSCar Institute of Geosciences and Exact Sciences São Paulo State University Unesp FAPESP: 2013/07296-2 FAPESP: 2013/12993-4 FAPESP: 2017/12437-5 CNPq: 473568/2013-6

Metal molybdate compounds have attracted considerable attention due to their technological applications. Herein, we demonstrate the controllable synthesis of cerium molybdate (Ce2(MoO4)3) nanocrystals via the co-precipitation method followed by microwave-assisted hydrothermal (MAH) treatment at 150 C during different times (15, 30 and 60 min). The effect of MAH treatment time on the microstructural, optical, and ozone gas-sensing properties of these nanocrystals was investigated. X-ray diffraction (XRD) and Raman spectroscopy measurements revealed that the samples presented a single-crystalline phase with scheelite-type tetragonal structure. Field emission gun scanning electron microscopy (FEG-SEM) images showed that the MAH conditions favored changes in the Ce2(MoO4)3 nano crystal morphology. Photoluminescence (PL) measurements indicated a significant enhancement of PL emission with MAH time, suggesting an increase in the intrinsic defects formed during the MAH treatment. The gas-sensing performance of cerium molybdate nanocrystals towards sub-ppm ozone levels was also investigated. The experiments revealed complete recovery and good repeatability as well as good sensor response, which was improved in the sample synthesized at longer MAH time

Strontium titanate nanoparticles have attracted much attention due to their physical and chemical properties, especially as photocatalysts under ultraviolet irradiation. In this paper, we analyze the effect of heating rate during the crystallization process of SrTiO3 nanoparticles in the degradation of organic pollutants. The relationship between structural, morphological and photocatalytic properties of the SrTiO3 nanoparticles was investigated using different techniques. Transmission electron microscopy and N2 adsorption results show that particle size and surface properties are tuned by the heating rate of the SrTiO3 crystallization process. The SrTiO3 nanoparticles showed good photoactivity for the degradation of methylene blue, rhodamine B and methyl orange dyes, driven by a nonselective process. The SrTiO3 sample with the largest particle size exhibited higher photoactivity per unit area, independent of the molecule to be degraded. The results pointed out that the photodegradation of methylene blue dye catalyzed by SrTiO3 is caused by the action of valence band holes (direct pathway), and the indirect mechanism has a negligible effect, i.e. degradation by O2 (-•) and (•) OH radicals attack.

Made available in DSpace on 2020-12-12T00:56:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Material processing has become essential for the proper control, tuning and consequent application of the properties of micro/nanoparticles. In this case, we report herein the capability of the microwave-assisted hydrothermal (MAH) method to prepare the SrTiO3 compound, as a case study of inorganic compounds. Analyses conducted by X-ray diffraction, X-ray photoelectron and X-ray absorption spectroscopies confirmed that the MAH route enables the formation of pristine SrTiO3. The results indicated that the combination of thermal and non-thermal effects during the MAH treatment provides ideal conditions for an efficient and rapid synthesis of pristine SrTiO3 mesocrystals. Scanning electron microscopy images revealed a cube-like morphology (of ca. 1 μm) formed via a self-assembly process, influenced by the MAH time. Additionally, photoluminescence measurements revealed a broad blue emission related to intrinsic defects, which decreased with the MAH synthesis time. Laboratory of Nanostructured Multifunctional Materials Federal University of São Carlos, Rodovia Washington Luiz, km 235 Institute of Geosciences and Exact Sciences São Paulo State University Unesp Institute of Physics Federal University of Goiás, Alameda Palmeiras s/n Institute of Chemistry Federal University of Uberlândia Institute of Physics of São Carlos University of São Paulo, Avenida Trabalhador São Carlos INCTMN Physical and Mathematics Institute (IFM) Universidade Federal de Pelotas Campus Universitário Capão Do Leão Center for Development of Functional Materials Federal University of São Carlos, Rodovia Washington Luiz, km 235 Departamento Química-Física y Analítica Universitat Jaume i Institute of Geosciences and Exact Sciences São Paulo State University Unesp

Made available in DSpace on 2018-11-27T00:47:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-10-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) Brazilian Nanotechnology National Laboratory, LNNano, Campinas, SP, Brazil We report for the first time a rapid preparation of Zn1-2xCoxNixO nanoparticles via a versatile and environmentally friendly route, microwave-assisted hydrothermal (MAH) method. The Co, Ni co-doped ZnO nanoparticles present an effect on photoluminescence and electrochemical properties, exhibiting excellent electrocatalytic performance compared to undoped ZnO sample. Photoluminescence spectroscopy measurements indicated the reduction of the green-orange-red visible emission region after adding Co and Ni ions, revealing the formation of alternative pathways for the generated recombination. The presence of these metallic ions into ZnO creates different defects, contributing to a local structural disorder, as revealed by Raman spectra. Electrochemical experiments revealed that the electrocatalytic oxidation of dopamine on ZnO attached to multi-walled carbon nanotubes improved significantly in the Co, Ni co-doped ZnO samples when compared to pure ZnO. (C) 2015 Elsevier Inc. All rights reserved. Univ Fed Uberlandia, Inst Quim, BR-38400902 Uberlandia, MG, Brazil Univ Estadual Paulista, LIEC, Inst Quim, BR-14800900 Araraquara, SP, Brazil Univ Estadual Paulista, LIEC, Inst Quim, BR-14800900 Araraquara, SP, Brazil FAPEMIG: APQ-00988-13 FAPEMIG: CEX - RED-00010-14 Brazilian Nanotechnology National Laboratory, LNNano, Campinas, SP, Brazil: XPS-18304

A microwave-assisted hydrothermal method was applied to synthesize BaZr1xHfxO3, (BZHO) solid solutions at a low temperature, 140 1C, and relatively short times, 160 min. The detailed features of the crystal structure, at both short and long ranges, as well as the crystal chemistry doping process, are extensively analysed. X-ray diffraction measurements and Raman spectroscopy have been used to confirm that pure and Hf-doped BZO materials present a cubic structure. Extended X-ray absorption fine structure (EXAFS) spectra indicate that Hf4+ ions have replaced the Zr4+ ions on the 6-fold coordination and a subsequent change on the Ba2+ 12-fold coordination can be sensed. X-ray absorption near-edge structure (XANES) spectroscopy measurements reveal a local symmetry breaking process, associated to overlap of the 4d–2p and 5d–2p orbitals of Zr–O and Hf–O bonds, respectively. Field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HRTEM) show the mesocrystalline nature of self-assembled BZHO nanoparticles under a dodecahedron shape. In addition first principle calculations were performed to complement the experimental data. The analysis of the band structures and density of states of the undoped BZO and doped BZHO host lattice allow deep insight into the main electronic features. The theoretical results help us to find a correlation between simulated and experimental Raman modes and allow a more substantial interpretation of crystal structure. Brazilian research funding institution FAPESP. 2009/17752-0 FAPERGS. 2031-2551/13-9SIAS CNPq (MCT/CNPq). 458452/2014-9 Generalitat Valenciana. Prometeo/2009/053 Ministerio de Ciencia e Innovacion. CTQ-2012-36253-C03-01 Programa de Cooperacion Cientificacon Iberoamerica (Brazil), Ministerio de Educacion. PHB2009-0065-PC

We report on the chemiresistive gas sensing characteristics of ZnO nanorods (NRs) modified by a thin layer of nickel phthalocyanine (NiPc). Ozone detection was carried out through electrical measurements with an optimized performance at 250°C, good reproducibility and suitable concentration range (from 80 to 890 ppb) for technological applications. The hybrid NiPc:ZnO films had superior performance to pure ZnO nanorods in terms of response time and sensitivity. The response times were 22 s and 26 s, respectively, whereas the ratio of resistances under ozone and air was 3.27 for NiPc:ZnO films and 2.56 for the pure ZnO NRs. The improvement in response time is attributed to the large surface area generated with the coating of the ZnO nanorods with the NiPc layer. Significantly, images taken with field-emission scanning electron microscopy (FE-SEM) indicated that the ZnO nanorods were fully covered with NiPc. X-ray diffraction measurements (XRD) revealed a preferential growth of the nanorod-like structures along the [100] direction. In summary, a successful approach has been developed to functionalize ZnO nanorods, which is promising for detection of ppb levels of ozone gas.

Made available in DSpace on 2018-11-26T17:55:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-10-25 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Brazilian Nanotechnology National Laboratory (LNNano), Microfabrication laboratory, Campinas, SP, Brazil Generalitat Valenciana Ministerio de Ciencia e Innovacion Programa de Cooperacion Cientifica con Iberoamerica (Brazil) Ministerio de Educacion This manuscript addresses the synthesis of one-dimensional (1D) alpha-Ag2WO4 nanorod-like structures via a microwave-assisted hydrothermal method to be used as an acetone gas sensor. The nanorods showed excellent gas-sensing performance, evidenced by their sensor response and repeatability, as well as a good range of detection (0.5-20.0 ppm). The manuscript also proposes an easy and efficient way of obtaining 1-D alpha-Ag2WO4 nanorods that exhibit remarkable acetone sensing properties. (C) 2016 Elsevier B.V. All rights reserved. Univ Estadual Paulista, Inst Quim, LIEC, POB 355, BR-14800900 Araraquara, SP, Brazil Univ Sao Paulo, Inst Fis Sao Carlos, Ave Trabalhador Sao Carlense 400, BR-13566590 Sao Carlos, SP, Brazil Univ Fed Sao Paulo, Dept Fis, Rodovia Washington Luiz, Sao Carlos, SP, Brazil DQ GERATEC Univ Estadual Piaui, BR-64002150 Teresina, PI, Brazil Univ Jaume 1, Dept Quim Fis & Analit, Campus Riu Sec, E-12080 Castellon de La Plana, Spain Aix Marseille Univ, CNRS UMR 7334 IM2NP, FS St Jerome S152, F-13397 Marseille, France Univ Estadual Paulista, Inst Quim, LIEC, POB 355, BR-14800900 Araraquara, SP, Brazil FAPESP: 2013/09573-3 FAPESP: 2013/07296-2 FAPESP: 2012/15170-6 FAPESP: 479644/2012-8 FAPESP: 442076/2014-2 FAPESP: 304531/2013-8 Brazilian Nanotechnology National Laboratory (LNNano), Microfabrication laboratory, Campinas, SP, Brazil: 17168 Generalitat Valenciana: Prometeo/2009/053 Ministerio de Ciencia e Innovacion Programa de Cooperacion Cientifica con Iberoamerica (Brazil): CTO2009-14541-C02 Ministerio de Educacion: PHB2009-0065-PC

A detailed study of the structural, surface, and gas-sensing properties of nanostructured Co

Made available in DSpace on 2018-12-11T16:59:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-03-15 Small-angle X-ray scattering (SAXS) and nitrogen adsorption were used to study ambient pressure drying (APD) silica aerogels prepared from hydrolysis of tetraethoxysilane (TEOS) with additions of sodium dodecyl sulfate (SDS). The surfactant-extracted precursor wet gels have presented mass-fractal structure with typical fractal dimension 2.25 in a SAXS characteristic length scale from ∼10 nm to ∼0.35 nm. Hydrophobic APD aerogels with typical specific surface of 800 m2/g and bulk density of 0.20 g/cm3 were obtained after silylation of the precursor wet gels with a mixture of hexamethyldisiloxane (HMDSO) and trimethylchlorosilane (TMCS). The pore volume and the mean pore size of the APD aerogels increased with increasing the SDS quantity. APD aerogels presented most of the mass-fractal characteristics of the precursor wet gels at large length scales. The radius of gyration of the clusters of the APD aerogels (typically 17 nm) increased with increasing the SDS quantity, while the radius of the silica primary particles (typically 2.0 nm) increased at first with the addition of SDS (with respect to the sample without SDS) and decreased regularly afterward with increasing the SDS quantity. The primary particles presented yet some internal inhomogeneity and a diffuse-boundary interface with thickness of about 0.7 nm, according to a linear-gradient model for the diffuse boundary. Unesp-Univ Estadual Paulista IGCE Departamento de Física, Cx.P. 178 Unesp-Univ Estadual Paulista IQ Departamento de Bioquímica e Tecnologia, Rua Prof. Francisco Degni, 55 Unesp-Univ Estadual Paulista IGCE Departamento de Física, Cx.P. 178 Unesp-Univ Estadual Paulista IQ Departamento de Bioquímica e Tecnologia, Rua Prof. Francisco Degni, 55

This paper describes the effect of using different titanium precursors on the synthesis and physical properties of SrTiO3powders obtained by microwave-assisted hydrothermal method. X-ray diffraction measurements, X-ray absorption near-edge structure (XANES) spectroscopy, field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HRTEM) were carried out to investigate the structural and optical properties of the SrTiO3spherical and cubelike-shaped particles. The appropriate choice of the titanium precursor allowed the control of morphological and photoluminescence (PL) properties of SrTiO3compound. The PL emission was more intense in SrTiO3samples composed of spherelike particles. This behavior was attributed to the existence of a lower amount of defects due to the uniformity of the spherical particles.

Made available in DSpace on 2018-11-26T17:55:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Brazilian Nanotechnology National Laboratory, LNNano, Campinas, SP, Brazil The use of nanostructured heterojunctions has been a promising option for hindering the charge recombination and thus enhancing the photocatalytic performance of catalysts. Here we present a simple strategy to hierarchically grow heterostructures using a hydrothermal treatment route. A buffer SnO2 film was produced by a sol-gel derived method, resulting in a film of approximately 100 nm composed of 5-10 nm nanoparticles. X-ray diffraction and scanning electron microscopy revealed preferential growth of the nanorod-like structures along the c-axis perpendicular to the SnO2 film, with an average nanorod diameter and length of approximately 160 nm and 1.5 mu m, respectively. The photoluminescence spectra of ZnO-SnO2 revealed a reduction in UV emission compared to individual ZnO nanorods, indicating that the recombination of the photogenerated carriers was inhibited in the heterojunction. This behavior was confirmed by evaluating the photocatalytic performance of such films against methylene blue degradation, showing that the as-prepared ZnO-SnO2 heterojunction was superior to the individual semiconductors, ZnO and SnO2. Univ Estadual Paulista, Inst Quim, LIEC, BR-14800900 Araraquara, SP, Brazil EMBRAPA Instrumentacao, BR-13560970 Sao Carlos, SP, Brazil Univ Sao Paulo, Inst Fis Sao Carlos, BR-13566590 Sao Carlos, SP, Brazil Univ Fed Sao Carlos, Inst Fis, BR-13565905 Sao Carlos, SP, Brazil Univ Estadual Paulista, Inst Quim, LIEC, BR-14800900 Araraquara, SP, Brazil CNPq: 442076/2014-2 FAPESP: 2013/09573-3 FAPESP: 2013/07296-2 FAPESP: 2012/15170-6 FAPESP: 2013/13888-0 Brazilian Nanotechnology National Laboratory, LNNano, Campinas, SP, Brazil: XPS-18304 Brazilian Nanotechnology National Laboratory, LNNano, Campinas, SP, Brazil: TEM-18566

Made available in DSpace on 2018-11-26T15:31:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Nanostructured semiconducting oxides have been used as resistive gas sensors of toxic and non-toxic gases, but little emphasis has been placed on ozone sensing. Here we present a new ozone gas sensor based on hierarchical NiCo2O4 cubic structures synthesized via a facile urea-assisted co-precipitation method and annealed at 450 degrees C, which showed a low detection level. Ozone detection was carried out through electrical measurements with an optimized performance at 200 degrees C, with fast response (similar to 32 s) and recovery (similar to 60 s) time with suitable concentration range (from 28 to 165 ppb) for technological applications. Furthermore, NiCO2O4 platelets are selective to ozone compared to other oxidizing and reducing gases. The low detection level can be attributed to the coexistence of 3D structures based on hexagonal platelet-like and porous flower-like shape, which were revealed by field emission scanning electron microscopy (FE-SEM). In summary, NiCo2O4 is promising for detection of sub-ppb levels of ozone gas. Univ Sao Paulo, Sao Carlos Inst Phys, CP 369, BR-13560970 Sao Carlos, SP, Brazil Sao Paulo State Univ, Inst Chem, LIEC, POB 355, BR-14800900 Araraquara, SP, Brazil Myongji Univ, Dept Energy Sci & Technol, Yongin, South Korea Aix Marseille Univ, CNRS IM2NP, UMR 7334, FS St Jerome S152, F-13397 Marseille, France Sao Paulo State Univ, Inst Chem, LIEC, POB 355, BR-14800900 Araraquara, SP, Brazil FAPESP: 2014/23546-1

In this manuscript, we report an investigation into the sensitivity of two oxidizing gases (ozone and nitrogen dioxide) for nanocrystalline SrTi 0.85 Fe 0.15 O 3 thin films deposited by the electron beam physical vapor deposition technique. Annealing treatment at 500 °C enhanced the crystallization and surface roughness of the thin film. Electrical measurements revealed that the thin film was sensitive to oxidizing gases, especially to low ozone gas levels, exhibiting a fast response time, a short recovery time as well as good reproducibility and reversibility. These findings demonstrate the great potential of the SrTi 0.85 Fe 0.15 O 3 compound to be applied as a selective ozone gas sensor.

This paper reports on a new ozone gas sensor based on α-Ag₂WO₄ nanorod-like structures. Electrical resistance measurements proved the efficiency of α-Ag₂WO₄ nanorods, which rendered good sensitivity even for a low ozone concentration (80 ppb), a fast response and a short recovery time at 300 °C, demonstrating great potential for a variety of applications.

A novel and promising ozone gas sensor based on α-Ag2WO4 rod-like structures is obtained via a microwave-assisted hydrothermal method. The electrical resistance measurements show a good gas sensor performance of nanorods at an operating temperature of 300 °C, especially a fast response and a short recovery time.

We report herein a detailed study on the influence of microwave-assisted hydrothermal (MAH) treatment time on both long and short range structures around Ti atoms of SrTiO3 powders. Few studies have been carried out on short-order structural properties as well as the relationship between the local order and the SrTiO3 photocatalytic properties. We use X-ray diffraction to determine the long-range structure, while the local environment around the Ti atom is probed with X-ray absorption spectroscopy and the vibration frequencies are investigated by Raman spectroscopy. The faster crystallization of SrTiO3 powders provided by the MAH system resulted in large distortions of Ti–O bond lengths which remain unchanged even for a longer MAH treatment time. Despite the long-range structure being associated with ideal TiO6 clusters, X-ray absorption spectroscopy measurements identified the presence of undercoordinated TiO5 clusters. Compared with the reference bulk SrTiO3, the hierarchical SrTiO3 cube-like shape showed enhanced photocatalytic activity, which was associated with the presence of these TiO5 clusters. Field emission scanning electron microscopy (FE-SEM) revealed that the superstructures based on a cube-like shape are formed by an assembly process, becoming well defined as a function of MAH treatment time.

We report on the use of nanocrystalline SrTi1−xFexO3 (STF) for sensing ozone gas. Amorphous thin films were evaporated by the electron-beam physical vapor deposition technique and then converted to a polycrystalline form, as shown by X-ray diffraction patterns, after ex situ annealing at a relatively low temperature (550 °C). The influence of the iron content on the microstructure was investigated by both scanning electron microscopy (SEM) and atomic force microscopy (AFM), which revealed that the surface roughness of the films increased slightly as the amount of iron increased. Electrical resistance measurements were carried out to determine the response of the films upon exposure to ozone and when compared to other oxide metal sensors, STF films can also be considered as good candidates for application as ozone gas sensors.

Background: Leptospirosis is a re-emerging zoonosis with protean clinical manifestations. Recently, the importance of pulmonary hemorrhage as a lethal complication of this disease has been recognized. In the present study, five human necropsies of leptospirosis (Weil‘s syndrome) with extensive pulmonary manifestations were analysed, and the antibodies expressed in blood vessels and cells involved in ion and water transport were used, seeking to better understand the pathophysiology of the lung injury associated with this disease. Principal Findings: Prominent vascular damage was present in the lung microcirculation, with decreased CD34 and preserved aquaporin 1 expression. At the periphery and even inside the extensive areas of edema and intraalveolar hemorrhage, enlarged, apparently hypertrophic type I pneumocytes (PI) were detected and interpreted as a non-specific attempt of clearence of the intraalveolar fluid, in which ionic transport, particularly of sodium, plays a predominant role, as suggested by the apparently increased ENaC and aquaporin 5 expression. Connexin 43 was present in most pneumocytes, and in the cytoplasm of the more preserved endothelial cells. The number of type II pneumocytes (PII) was slightly decreased when compared to normal lungs and those of patients with septicemia from other causes, a fact that may contribute to the progressively low PI count, resulting in deficient restoration after damage to the alveolar epithelial integrity and, consequently, a poor outcome of the pulmonary edema and hemorrhage. Conclusions: Pathogenesis of lung injury in human leptospirosis was discussed, and the possibility of primary noninflammatory vascular damage was considered, so far of undefinite etiopathogenesis, as the initial pathological manifestation of the disease.

We report herein for the first time a facile synthesis method to obtain SrTi1−xFexO3 nanocubes by means by a microwave-assisted hydrothermal (MAH) method at 140 °C. The effect of iron addition on the structural and morphological properties of SrTiO3 was investigated. X-ray diffraction measurements show that all STFO samples present a cubic perovskite structure. X-ray absorption spectroscopy at Fe absorption K-edge measurements revealed that iron ions are in a mixed Fe2+/Fe3+ oxidation state and preferentially occupy the Ti4+-site. UV-visible spectra reveal a reduction in the optical gap (Egap) of STFO samples as the amount of iron is increased. An analysis of the data obtained by field emission scanning electron microscopy points out that the nanoparticles present a cubic morphology independently of iron content. According to high-resolution transmission electron microscopy results, these nanocubes are formed by a self-assembly process of small primary nanocrystals.

The present study aimed to verify the time course of the effects of environmental levels of urban air pollution toxicity on lung arterioles. BALB/c mice (n=56) were continuously exposed to selective chambers equipped with (filtered, F) or without (non-filtered, NF) filter devices for particles and toxic gases for 24h/day, over 14, 21, 30 or 45 days. After exposure, we evaluated the lumen-wall relationship (an estimator of arteriolar narrowing), endothelial nitric oxide synthase (eNOS) and endothelin type A receptor (ETAr) expression in the vascular wall and inflammatory influx of the peribronchiolar area. Concentrations of fine particulate matter (PM

PURPOSE: This study was carried out in Monte Negro (state of Rondônia), a village in the Brazilian western Amazon region, where a University of São Paulo Medical School program for medical student training in rural assistance took place. It aimed to determine the prevalence of hepatitis B virus and hepatitis C virus, to investigate risk factors for infection, and to evaluate the State immunization program against hepatitis B virus in the region. METHODS: The study is a cross-sectional seroprevalence survey, comprising 267 volunteers who answered a comprehensive questionnaire and had blood samples collected, which were analyzed in São Paulo for the presence of antibodies against hepatitis B virus (Hbs Ag, anti-Hbs, and anti-Hbc) and hepatitis C virus using commercial kits. Data were stored in a specific data bank, and the association between seropositivity and potential risk factors was analyzed by means of uni-, bi-, and multi-variate analysis, considering ±5%. RESULTS: The seroprevalence of hepatitis B virus was 61.79% and of hepatitis C virus was 0.38%. Statistical analysis on the data bank showed that the prevalence of hepatitis B virus rose significantly with age, especially after adolescence. Infection was higher in those coming from outside the state of Rondônia. Exposure to vaccination against hepatitis B virus was higher in younger individuals and in those who were born in Rondônia. CONCLUSION: Monte Negro is a highly endemic region for hepatitis B virus but not for hepatitis C virus. Our results also provide indirect evidence indicating a significant improvement in the immunization program in Rondônia in recent years. OBJETIVOS: O presente estudo foi realizado em Monte Negro, Rondônia, Amazônia Oriental, onde um projeto de acadêmicos de Medicina da Universidade de São Paulo promoveu assistência médica à população rural. O objetivo foi determinar a soroprevalência de Hepatite B e Hepatite C, investigar os fatores de risco para sua infecção e avaliar o status imunológico vacinal contra Hepatite B nesta região. MÉTODOS: O estudo é uma pesquisa de corte transversal de soroprevalência, compreendendo 267 voluntários que tiveram suas amostras sanguíneas coletadas após preenchimento de um questionário. As amostras foram analisadas em São Paulo usando kits comerciais pesquisando anticorpos contra Hepatite B (AgHBs, Anti-HBs e Anti-HBc) e Hepatite C . Um banco de dados montado através do questionário foi analisado em relação aos resultados sorológicos com testes uni-, bi-, e multivariado, considerando ± = 5%. RESULTADOS: A soroprevalência do VHB encontrada foi de 61.79% e do Hepatite C, 0.38%. A análise dos possíveis fatores de risco mostrou que a prevalência de Hepatite B aumenta com a idade, especialmente após a adolescência, além de ser maior em aqueles nascidos em Rondônia. A exposição à vacinação contra Hepatite B foi maior em indivíduos jovens e aqueles nascidos em Rondônia. CONCLUSÃO: Monte Negro é uma região altamente endêmica para Hepatite B , mas não para Hepatite C . Ademais, os resultados obtidos evidenciam uma significativa melhora no programa de imunizações em Rondônia nos anos recentes.