DET - Departamento de Engenharia Têxtil

URI Permanente desta comunidadehttps://repositorio.ufrn.br/handle/1/134

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Spectral power distributions for the CIE stimuli
(Wiley Periodicals, LLC, 2001-10-08) Bezerra, Clovis de Medeiros; Hawkyard, C. J.
The CIE reference colour stimuli, X, Y, and Z, were derived by constructing a triangle outside the R,G,B triangle and outside the area bounded by the spectrum locus and the purple line. By this means, all colours, including monochromatic ones, have positive tristimulus values. The colour-matching functions are the relative quantities of these stimuli required to be mixed additively to match the equal energy monochromatic colours. The stimuli are not realizable as light sources, and the CIE has not specified their spectral power distributions. There is an infinite num ber of spectral power distributions whose properties meet the prerequisites for X (X 5 100, Y 5 0, Z 5 0), Y (0, 100, 0), and Z (0, 0, 100), and two possible sets have been calculated by different methods. These curves could be used as primary red, green, and blue lights in additive mixing to produce synthetic reflectance curves, which are useful in the specification of on-screen colours, and as a means of pro ducing colour constant standards
Effects of gas composition during plasma modification of polyester fabrics
(ELSEVIER, 2006) Costa, Thércio Henrique de Carvalho; Feitor, Michelle Cequeira; Alves Júnior, Clodomiro; Freire, P. B.; Bezerra, Clovis de Medeiros
In order to increase the hydrophilicities and to improve dyeability, poly(ethylene terephathalate) (polyester) fabrics were treated in low pressure and temperature plasma. Different plasma atmosphere were used in this work, leaving the gas type (oxygen, nitrogen, methane and hydrogen) as plasma variables, other parameters like pressure, exposure time, voltage and current were not variables in the process. After plasma treatment, the properties of the fabric, including surface morphology and chemical alteration, were investigated. The polyester fabrics treated with different plasma gases exhibited different morphological changes. The capillary method was applied to evaluate the improvement in water uptake of polyester fabrics, which indicated a good wettability to all atmospheres used in this work, except for a mixture containing methane, hydrogen and nitrogen
Computer match prediction for fluorescent dyes by neural networks
(John Wiley & Sons, 2006-06-22) Bezerra, Clovis de Medeiros; Hawkyard, C. J.
Fluorescent dyes present difficulties for match prediction due to their variable excitation and emission characteristics, which depend on a variety of factors. An empirical approach is therefore favoured, such as that used in the artificial neural network method. In this paper, the production of a database with four acid dyes (two fluorescent and two non-fluorescent) is described, along with the large number of mixture dyeings that were carried out. The data were used to construct a network connecting reflectance values with concentrations in formulations. The results show that, although time consuming, this approach is viable and accurate
Tratamento em plasma de tecido 100% Aramida para análise de molhabilidade
(2008-01-19) Costa, Thércio Henrique de Carvalho; Feitor, Michelle Cequeira; Alves Júnior, Clodomiro; Freire, P. B.; Bezerra, Clovis de Medeiros; Furtado, Duciane Oliveira de Freitas
Um tecido de fibras de Aramida (Kevlar) foi tratado em plasma de O2, Ar, e N2, a fim de estudar os efeitos sobre a hidrofilicidade deste material. Foram usadas as técnicas de arraste vertical e MEV (microscopia eletrônica de varredura) para analisar as amostras. As amostras tratadas em plasma de O2 e N2 apresentaram uma melhoria substancial na hidrofilidade, a qual foi atribuída à formação de rugosidade na superfície das fibras.
Caracterização de filmes de poliéster modificados por plasma de O2 a baixa pressão
(Universidade Federal do Rio de Janeiro, 2008-05-12) Costa, Thércio Henrique de Carvalho; Feitor, Michelle Cequeira; Alves Junior, Clodomiro; Bezerra, Clovis de Medeiros
Filmes de poliéster possuem um vasto campo de aplicação, devido algumas propriedades que são inerentes desse tipo de material, tais como boa resistência mecânica, resistência química a ácidos e bases e baixo custo de produção. Entretanto possuem limitações, como baixa tensão superficial, baixa rugosa, pouca afinidade com corantes, e pouca adesão, que impedem o uso dos mesmos para algumas finalidades principalmente quando esse uso requer que o material possua uma boa molhabilidade. Dentre as varias técnicas existentes para aumentar a tensão superficial, as técnicas que utilizam o plasma, como fonte energética, são as mais promissoras pela versatilidade e por não apresentar agentes nocivos ao meio. Então, tendo em vista a boa aceitabilidade do uso do plasma em materiais poliméricos, trataram-se filmes de poliéster usando plasma com atmosfera gasosa de oxigênio variando-se o tempo de tratamento de 10 - 60 min com incremento de 10 min a cada tratamento subseqüente. Após o tratamento por plasma as amostras foram caracterizadas por medidas de ângulo de contato, tensão superficial, espectroscopia Raman, Espectroscopia de infravermelho de reflexão total atenuada (IR-ATR), e microscopia de força atômica (AFM), onde foi caracterizado o aumento na molhabilidade dos filmes tratados por plasma bem como as variáveis que contribuíram para tal efeito. A técnica de plasma mostrou-se bastante eficiente na modificação de filmes de poliéster, uma vez que se obteve aumento na molhabilidade de todos os filmes tratados e sem nenhuma variação significativa com relação ao tempo de exposição das amostras pelo plasma, o que leva a propor que o tratamento por plasma tanto contribuiu para o aumento da molhabilidade através da implementação de grupos funcionais na superfície dos mesmos como com a criação de rugosidade superficial nas amostras
Surface modification of polyester fabric by non-thermal plasma treatment
(IOP Publishing Ltd, 2012) Silva, Ruthilene Catarina Lima da; Alves Júnior, Clodomiro; Nascimento, José Heriberto Oliveira do; Neves, J. R. O.; Teixeira, V.
In the present study it was carried out a surface modification of polyester fabric by plasma treatment with aim of providing hidrophilicity to fabric. In the process it were used three different gaseous atmosphere with mixtures of argon, nitrogen and/or oxygen [(1) Ar + N2 (4:2), (2) Ar + N2 +O2 (4:2:2) and N2 + O2 (2:0.6)] and maintained others parameters such as pressure, current and time of treatment fixed at 1.35 mBar, 0.08 A and 30 minutes, respectively. The plasma treatment was monitored by optical emission spectroscopy (OES) to identify the species presents in the plasma reactor. Chemical changes in the fabric surface after plasma treatments were determined by Fourier Transform Infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). Wicking properties were used to evaluate hydrophilicity of the fabric. Wicking measurement showed that the hydrophilicity of polyester fabric was remarkably improved after treatment and was explained by XPS analysis indicating higher presence of functional groups containing nitrogen and oxygen
Analysis and evaluation of shape memory alloy wires behaviour in weft-knitted fabrics
(Trans Tech Publications, 2012-11) Medeiros, José Ivan de; Fangueiro, Raul
It is widely acknowledged within the textile engineering community that Shape Memory Alloys (SMA), exhibit great potential for several applications. This paper presents the research undertaken at the University of Minho aiming to study the behaviour of weft-knitted fabrics produced with SMA nitinol® wires. SMA nitinol® wires of type B (which shows shape memory effect at body temperature) of 50, 127 and 210 µm diameters have been used to produce weftknitted fabrics with different loop types, e.g. stitch, tuck and miss. The influence of the loop type on the performance of the weft-knitted fabric, in terms of energy absorption, has been analyzed. Tensile tests were carried out according to ISO1462 standard, using a H100KS Hounsfield universal testing instrument. The results aim to help future applications of SMA in the development of new textile materials
Analysis of energy absorption for NiTi wires under different diameters and loop types
(The Textile Machinery Society of Japan, 2013) Medeiros, José Ivan de; Fangueiro, Raul
This paper presents the research undertaken at the University of Minho aiming to study the behaviour of 3D weft-knitted structures using Shape Memory Alloy (SMA) wires and elastomeric yarns, in order to produce dynamic structures as a support to answer specific situations and applications. Several samples were produced using NitinolR wires in different diameters and loop types. The Tensile tests were carried out being based to NP EN ISO 2062: 1993 standards, using a H100KS Hounsfield Universal Testing Instrument. The results showed that The 50 μm wire showed to be too thin to this propose;moreover, The 210 μm NiTi wire showed to be hard to process on the knitting machine due to its high stiffness;The 127 μm NiTi wire showed to be the best among them, due to the process and energy absorption ratio. Finally, for both NiTi wires in different diameters studied, tuck loop showed to have the highest energy absorption capacity
Dengue: prevenção e controle pelas ondas do rádio
(2014) Almeida Júnior, José Jailson de; Oliveira, Franklin Learcton Bezerra de; Araújo, Rayane Larissa Santos de; Brilhante, Magdalena Muryelle Silva; Silva, Dany Geraldo Kramer Cavalcanti e
INTRODUÇÃO: a dengue é uma doença viral que vem tomando grandes proporções mundialmente por possuir características endêmicas e epidêmicas, se alastrando por todo o mundo e provocando grande impac-to na saúde pública. OBJETIVO: apresentar as ações desenvolvidas nas rádios AM e FM do Projeto de Extensão Vigilância Ambiental em Saúde: ações integradas de controle da dengue no município de Santa Cruz/RN. MATERIAL E MÉTODOS: trata-se de um estudo descritivo do tipo relato de experi-ências sobre ações realizadas nas emissoras de rádio AM e FM do município de Santa Cruz/RN. RESULTADOS E DISCUSSÃO: as entrevistas tiveram boa repercussão, tendo em vista o público alcançado por meio das duas emissoras. CONCLUSÃO: acredita-se que o objetivo foi atingido, considerando que o programa de rádio proporciona um contato direto com o ouvinte, o que é reforçado com os apresentadores dos programas veicu-lados pelas emissoras
Azilsartan Increases Levels of IL-10, Down-Regulates MMP-2, MMP-9, RANKL/RANK, Cathepsin K and Up- Regulates OPG in an Experimental Periodontitis Model
(Faculté de Médecine de Nantes, France, 2014-05-12) Araújo, Aurigena Antunes de; Varela, Hugo; Brito, Gerly Anne de Castro; Medeiros, Caroline Addison Carvalho Xavier de; Araújo, Lorena de Souza; Nascimento, José Heriberto Oliveira do; Araújo Júnior, Raimundo Fernandes de
Aims The aim of this study was to evaluate the effects of azilsartan (AZT) on bone loss, inflammation, and the expression of matrix metallo proteinases (MMPs), receptor activator of nuclear factor κB ligand (RANKL), receptor activator of nuclear factor κB (RANK), osteoprotegerin (OPG), cyclooxygenase-2 (COX-2), and cathepsin K in periodontal tissue in a rat model of ligature-induced periodontitis. Materials and Methods Male Wistar albino rats were randomly divided into 5 groups of 10 rats each: (1) nonligated, water; (2) ligated, water; (3) ligated, 1 mg/kg AZT; (4) ligated, 5 mg/kg AZT; and (5) ligated, 10 mg/kg AZT. All groups were treated with saline or AZT for 10 days. Periodontal tissues were analyzed by histopathology and immunohistochemical detection of MMP-2, MMP-9, COX-2, RANKL, RANK, OPG, and cathepsin K. Levels of IL-1β, IL-10, TNF-α, myeloperoxidase (MPO), and glutathione (GSH) were determined by ELISA. Results Treatment with 5 mg/kg AZT resulted in reduced MPO (p<0.05) and IL-1β (p<0.05), increased levels of IL-10 (p<0.05), and reduced expression of MMP-2, MMP-9, COX-2, RANK, RANKL, cathepsin K, and increased expression of OPG. Conclusions These findings reveal that AZT increases anti-inflammatory cytokines and GSH and decreases bone loss in ligature-induced periodontitis in rats.
Photocatalytic properties of sisal fiber coated with nano titanium dioxide
(ELSEVIER, 2015) Oliveira, Fernando Ribeiro; Galvão, Felipe Mendonça Fontes; Nascimento, José Heriberto Oliveira do; Silva, Kesia Karina de Oliveira Souto; Medeiros, José Ivan de; Zille, Andrea
Molded sisal fibers dip-coated with titanium dioxide (TiO2) nanoparticles were physico-chemical characterized and tested for the photocatalytic treatment of textile wastewaters. The X-Ray powder diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and the scanning electron microscopy (SEM) analysis revealed uniform TiO2 nanoparticles deposition in the anatase phase with and average diameter of 32 nm. The sisal/TiO2 nanocomposite exhibits a remarkable photodegradation yield of methylene blue solution (92%) maintaining a good efficiency even after 5 washing cycles (70%). The nanocomposite also exhibits a remarkable fast photo-induced hydrophilicity decreasing the contact angle from 140º to 6º after 7 minutes of UV exposure. Sisal fibers revealed to be a promising substrate for TiO2 nanocomposites in wastewater treatment due to its low cost, low density, high specific strength and modulus, no health risk, easy availability and renewability
Extraction and characterization of cellulosic nanowhisker obtained from discarded cotton fibers
(ELSEVIER, 2015) Nascimento, José Heriberto Oliveira do; Luz, Rodrigo Farias; Galvão, Felipe Mendonça Fontes; Melo, José Daniel Diniz; Oliveira, Fernando Ribeiro; Ladchumananandasivam, Rasiah; Zille, Andrea
This study aimed to characterize cellulose nanowhiskers extracted from discarded cotton fibers. The nanocellulose was characterized by dynamic light scattering, zeta potential, Scanning Transmission Electron Microscopy (STEM), Atomic force microscopy (AFM) and X-ray powder diffraction (XRD). The nanocrystals are characterized by a rod-like morphology with sizes between 100 nm and 300 nm. The acidic hydrolyses applied to the extract nanocrystals increased the crystallinity index from 72 to 86%. The average length and diameter obtained were 98.1±4.7 and 8.0±3.4 nm, respectively. The aspect ratio of the fibers, around 12.3, was lower than the values usually reported in the literature. The dynamic light scattering results were in accordance with the nano crystal dimensions showing an average size of 235 nm. Cellulose nanowhiskers obtained from cotton rejected by textile industry due to their abundance, low cost, high crystallinity, strength, low weight and biodegradability, are the ideal candidates for the processing of polymer nanocomposites
Characterization and acidic properties of AlMCM-41 prepared by conventional and post-synthesis alumination
(Australian Journal of Chemistry, 2015) Nascimento, Rubens Maribondo do; Costa, Maria José Fonseca; Chellappa, Thiago; Araujo, Antonio Souza de; Fonseca, Viviane Muniz; Fernandes Júnior, Valter José; Pacheco, Jose G. A.
The catalysts analysed in the current work are variations of MCM-41. The properties of these highly ordered mesoporous aluminosilicates were adjusted by an isomorphous substitution of Si by a trivalent cation, in this case Al3þ, generating catalysts of the AlMCM-41 type. The materials were synthesized with a silicon/aluminium ratio of 40, through two methods of impregnation of the metal: conventional and post-synthesis alumination. With the aim of determining the density of the acid sites of the Al40MCM-41 prepared by post-synthesis and conventional alumination, studies of the adsorption of n-butylamine probe molecule were carried out. Further, the studied material was characterized by thermogravimetry measurements, providing the profile of decomposition of the samples, which allowed calculation of the densities of the acid sites. The model-free kinetic algorithms were applied in order to determinate conversion and apparent activation energy. Comparison of energy-dispersive X-ray fluorescence and X-ray photoelectron spectroscopy measurements indicated that the post-synthesis method was more favourable based on the metal positioning, ‘anchored’ in the surface of the catalyst. The textural properties of the calcined Al40MCM-41 prepared by post-synthesis and conventional alumination were characterized by X-ray diffraction, N2 isothermal adsorption measurements (Brunauer– Emmett–Teller and Barrett–Joyner–Halenda), transmission electron microscopy, and X-ray photoelectron spectroscopy.
Development of porous alumina membranes for treatment of textile effluent
(Taylor & Francis, 2015-02-27) Silva, Késia Karina de Oliveira Souto; Paskocimas, Carlos Alberto; Oliveira, Fernando R.; Nascimento, José Heriberto Oliveira do; Zille, Andrea
Ceramic porous membranes sintered at two different temperature using polyvinyl alcohol and ethylene glycol as binders, and composed of two types of α-alumina with different parti- cle sizes were investigated for the microfiltration of a textile effluent containing indigo dye, auxiliaries, heavy metals, oils, and solids. The physicochemical properties of the membranes and effluent were evaluated. X-ray diffraction, energy dispersive X-ray fluorescence spectros- copy, differential scanning calorimetry, and thermogravimetric analysis confirm that the thin membrane is composed of high crystalline and pure α-alumina. Scanning electron microscopy observation indicates that the membranes have smooth porous surface making it suitable for microfiltration applications. The membrane sintered at 1,450 ̊C exhibited higher water absorp- tion (WA) and apparent porosity than that sintered at 1,475 ̊C. The apparent specific gravity and flexural strength are in inverse correlation with the WA due to the enhanced densification of the membranes. The filtered effluent was evaluated using a membrane with an average pore size of 0.4 μm and a total porosity of 29.6%. The average values of rejection were 90% for color, 93% for suspended solids, 95% for turbidity, 60% for metals, and 73% for chemical oxygen demand. These results demonstrate that low-cost ceramic alumina membranes are a very promising advanced treatment for textile industrial effluents
Thin tin and tio2 film deposition in glass samples by cathodic cage
(Materials Research, 2015-04) Feitor, Michelle Cequeira; Sousa, Rômulo Ribeiro Magalhães de; Araújo, Francisco Odolberto de; Costa, Thercio Henrique de Carvalho; Nascimento, Igor Oliveira; Santos, Francisco Eroni Paes; Alves Júnior, Clodomiro
Thin nitride and titanium dioxide films were produced using an innovative technique called cathodic cage depositon. Uniformity, three-dimensionality and high rate deposition are some of the advantages of this technique. In this study we discuss the influences of temperature, treatment time and gaseous atmosphere on the characteristics of the deposited films. The TiN (titanium nitride) and TiO2 (titanium dioxide) films were produced using a high deposition rate of 2,5 μm/h at a work temperature and pressure of 400°C and 150 Pa respectively. EDS technique was used to identify the chemical composition of the thin film deposited, whilst Raman spectroscopy indicated the phases present confirmed by DRX analysis. The thickness of the deposited films was studied using electron microscopy scanning. The results based on the deposition parameters confirm the great efficiency and versatility of this technique, which allows a uniform three-dimensional film deposition on any material without the appearance of stress. Compared to other techniques, cathodic cage deposition enables deposition at lower temperatures
Telmisartan decreases inflammation by modulating TNF-a, IL-10, and RANK/RANKL in a rat model of ulcerative colitis
(Pharmacological Reports, 2015-06) Silva, Késia Karina de Oliveira Souto; Guerra, Gerlane Coelho Bernardo; Araujo, Aurigena Antunes de; Lira, George A.; Melo, Maryanne N.; Fernandes, Daline; Silva, Arthur L.; Araujo Junior, Raimundo Fernandes de
Background: Telmisartan is an antihypertensive angiotensin II receptor blocker. This antihypertensive shows antiinflammatory activity. Purpose: In this study, the antiinflammatory activity of telmisartan was tested in an acetic acid (10%) model of ulcerative colitis (UC) in rats. Methods: Rats were given 1, 3, and 5 mg/kg/day of telmisartan orally for 3 days before induction of UC. The same doses were also administered 2 and 24 h after induction. Rats from the non-colitis and non- treated colitis groups were administered vehicle (saline, 5 ml/kg) orally and another group received sulfasalazine (50 mg/kg/day). Colons tissue was analyzed by macroscopic, by histopathology, by the immunohistochemical examination of RANKL/RANK pathway; by ELISA analysis of the levels of IL-10, TNF-a, myeloperoxidase (MPO) and malonaldehyde (MDA). Results: Telmisartan at 5 mg/kg reduced levels of MPO, MDA, TNF-a and increased of IL-10 (p < 0.05). Additionally, telmisartan reduced macroscopic damage, number of ulcers, and inflammatory and histopathological processes such as neutrophil infiltration, changes in cytoarchitecture, and necrosis. Immunohistochemistry revealed down-regulation of nuclear factor-kappaB receptor/nuclear factor- kappaB ligand (RANK/RANKL) in groups treated with sulfasalazine or telmisartan. Conclusion: Telmisartan exerts beneficial effects in an acetic acid model of colitis in rats. These effects may be due to accelerated termination of the acute inflammatory phase, indicated by decreased TNF-a and increased production of IL-10 and low expression of RANKL and RANK. 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp.
Evaluation of aging in air of poly (ethylene terephthalat) in oxygen plasma
(Materials Research, 2015-10) Feitor, Michelle Cequeira; Alves Junior, Clodomiro; Bezerra, Clovis Medeiros; Sousa, Rômulo Ribeiro Magalhães de; Costa, Thercio Henrique de Carvalho
Polyester fabric samples – PET (poly (ethylene terephtalate)), were treated with oxygen plasma, in order to alter the hydrophilicity of such material. The process parameters: working pressure, current, tension and temperature were kept constant, varying only the treatment time. In order to evaluate the change caused on samples hydrophilicity, as well as the influence of the treatment time, the vertical wicking test was used. The samples were stored at standard temperature and pressure conditions, and their wettability were measured one day after the treatment and repeated after 30, 60 and 360 days, in order to check the stability of the effects produced. Scanning electron microscopy (SEM), Raman and ATR (Attenuated total reflection) spectroscopies were used to evaluate physical and chemical alterations on the samples surface. The results have shown a substantial improvement on the hydrophilicity of the treated samples compared to the non-treated sample.
Estudo comparativo da atuação do enfermeiro no controle de dengue e febre chikungunya
(FapUNIFESP (SciELO), 2016) Almeida Júnior, José Jailson de; Oliveira, Franklin Learcton Bezerra de; Millions, Rejane Medeiros; Costa, Marcelo Viana da; Silva, Dany Geraldo Kramer Cavalcanti e
O objetivo deste estudo foi analisar a atuação dos enfermeiros das Estratégias de Saúde da Família no controle de dengue e febre chikungunya nos municípios de Parnamirim e Santa Cruz/RN. Trata-se de um estudo exploratório, descritivo, com abordagem qualitativa de tratamento e análise de dados. A coleta foi realizada entre novembro e dezembro de 2015 por meio de uma entrevista gravada, voltada às questões que abordam a ação da enfermagem e sua equipe no controle de dengue e febre chikungunya no campo de atuação da ESF. Utilizou-se como método de observação dos dados a análise de conteúdo de Bardin. Após análise, houve criação de duas categorias – educação em saúde e campanhas pontuais. Na primeira, os entrevistados informaram realizar palestras educativas, mas não explicam a metodologia usada e nem a participação popular, como também a articulação com o setor de endemias da cidade para fortalecer a discussão. Na segunda, algumas ações são assistencialistas de caráter campanhista/higienista, realizadas pelos enfermeiros dos municípios em campanhas de “higienização” e “limpeza”, as quais se mostram bastante presentes nas falas dos entrevistados. Há uma forte presença desse modelo enraizada tanto nas ações quanto na realização de atividades educativas, usando como metodologia a palestra. Além disso, há necessidade de se realizar mais estudos que aprofundem o tema abordado, a julgar por uma amostra pequena, especialmente no município de Parnamirim
Spectrophotometric characterization of simple glazings for a modular façade
(ELSEVIER, 2016-09) Sacht, Helenice; Bragança, Luis; Almeida, Manuela; Nascimento, Jose Heriberto Oliveira do; Caram, Rosana
A large variety of transparent materials is available for uses in buildings façades and all glazing properties must be considered in their choice. Such a selection should be a careful process of evaluation and weighing of tradeoffs. The correct glazing specifications for façades can reduce energy consumption in buildings, because the heat exchange and passage of radiation into the building as light and heat occur through transparent surfaces. Therefore, glazing significantly contributes to the heat transfer between outdoor and indoor spaces, which act directly on daylighting and thermal comfort. This manuscript addresses a spectrophotometric characterization of glazings for the study of components for the design of a modular façade system based on the climate of Portugal. The study focused on results of spectrophotometric measurements of an optical behavior in different solar spectrum intervals (ultraviolet, visible and near infrared), specifically the transmittance of some types of simple glazings. The results show the percentage of transmission to spectrum intervals, which enabled the analysis (OK?) of the efficiency of the glazing regarding daylighting and correlation to the thermal performance. Indications for specifications and adequate uses based on transmission of transparent surfaces have been obtained and complemented the datasheets available from the manufactures
Effect of Ag clusters doping on the photoluminescence, photocatalysis and magnetic properties of ZnO nanorods prepared by facile microwave-assisted hydrothermal synthesis
(Springer, 2017-04-13) Souza, Renata Priscilla de Araújo; Motta, Fabiana Vilella da; Nascimento, José Heriberto Oliveira do; Delmonte, Maurício Roberto Bomio; Borges, Filipe Martel de Magalhães; Corrêa, Marcio Assolin; Silva, Elson Longo da; Li, Maximo Siu; Bohn, Felipe; Paskocimas, Carlos Alberto
We report a chemical route to synthesize stabilized ZnO:Ag nanoparticles (NPs) combined with nanosized metallic Ag using microwave-assisted hydrothermal synthesis. We employ X-ray diffraction (XRD), field emission guns scanning electron microscopy, transmission electron microscopy, spectrophotometry, photodegradation, photoluminescence and magnetic characterizations to investigate the structural, morphological, photocatalytic and magnetic properties of ZnO:Ag samples with different Ag concentrations. We verify through XRD results the standard wurtzite crystalline phases and face-centered cubic for metallic Ag NPs. Moreover, we confirm through spectrophotometry the photocatalysis in the samples. The Ag clusters doping the pure material causes the shift from green to yellow-red, which are lower energy wavelengths, thus corroborating changes of its electrical properties due to the decreased gap. We interpret the magnetic properties in terms of the nanosizing and similar effects. Under these conditions, we show the improvement of the photocatalytic and magnetic properties of ZnO NPs

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