On the effect of aluminum on the microstructure and mechanical properties of CrN coatings deposited by HiPIMS

BNDES - BANCO NACIONAL DE DESENVOLVIMENTO ECONÔMICO E SOCIALCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOHard coatings are a suitable solution for increasing the lifetime of tools and components employed in different industrial applications. Coatings of transition metal nitrides have great use for tribological applications due to due to their unique mechanical properties. Although widely employed, current deposition methods such as cathodic arc evaporation produce coatings with many defects, which in turn reduce the resistance to wear, especially under severe conditions. High Power Impulse Magnetron Sputtering is a novel physical vapor deposition technique that produces homogeneous coatings. In this study, CrN and CrAlN monolayer coatings were deposited on AISI 304 stainless steel substrates using HiPIMS. X-Ray Diffraction, Scanning Electron Microscopy, Atomic Force Microscopy were used to evaluate the microstructure, phase composition, morphology and chemical composition of the coating. Results showed that HiPIMS is a promising technique to deposit CrN and CrAlN homogeneous coatings with high hardness and good adhesion to the substrate.21316BNDES - BANCO NACIONAL DE DESENVOLVIMENTO ECONÔMICO E SOCIALCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOBNDES - BANCO NACIONAL DE DESENVOLVIMENTO ECONÔMICO E SOCIALCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO640/2012sem informaçãosem informaçã

Self-sterilizing ormosils surfaces based on photo-synzthesized silver nanoparticles

Medical device-related infections represent a major healthcare complication, resulting in potential risksfor the patient. Antimicrobial materials comprise an attractive strategy against bacterial colonizationand biofilm proliferation. However, in most cases these materials are only bacteriostatic or bactericidal,and consequently they must be used in combination with other antimicrobials in order to reach theeradication condition (no viable microorganisms). In this study, a straightforward and robust antibac-terial coating based on Phosphotungstate Ormosil doped with core-shell (SiO2@TiO2) was developedusing sol-gel process, chemical tempering, and Ag nanoparticle photoassisted synthesis (POrs-CS-Ag).The coating was characterized by X-ray Fluorescence Spectroscopy (XRF), Field Emission ScanningElectron Microscopy (FE-SEM), Atomic Force Microscopy (AFM) and X-ray Photoelectron Microscopy(XPS). The silver free coating displays low antibacterial activity against Staphylococcus aureus and Pseu-domonas aeruginosa, in opposition to the silver loaded ones, which are able to completely eradicate thesestrains. Moreover, the antimicrobial activity of these substrates remains high until three reutilizationcycles, which make them a promising strategy to develop self-sterilizing materials, such as POrs-CS-Ag-impregnated fabric, POrs-CS-Ag coated indwelling metals and polymers, among other materials.Fil: Gonçalves, Lidiane Patrícia. Universidade de Sao Paulo; BrasilFil: Miñan, Alejandro Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Benítez, Guillermo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Fernandez Lorenzo, Monica Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Vela, Maria Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Schilardi, Patricia Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Ferreira Neto, Elias Paiva. Universidade de Sao Paulo; BrasilFil: Noveletto, Júlia Cristina. Universidade de Sao Paulo; BrasilFil: Correr, Wagner Rafael. Universidade de Sao Paulo; BrasilFil: Rodrigues Filho, Ubirajara Pereira. Universidade de Sao Paulo; Brasi

Detection of the peanut allergen Ara h 6 in foodstuffs using a voltammetric biosensing approach

A voltammetric biosensor for Ara h 6 (a peanut allergen) detection in food samples was developed. Gold nanoparticle-modified screen-printed carbon electrodes were used to develop a sandwich-type immunoassay using two-monoclonal antibodies. The antibody-antigen interaction was detected through the electrochemical detection of enzymatically deposited silver. The immunosensor presented a linear range between 1 and 100 ng/ml, as well as high precision (inter-day RSD ≤9.8 %) and accuracy (recoveries ≥96.7 %). The detection and quantification limits were 0.27 and 0.88 ng/ml, respectively. It was possible to detect small levels of Ara h 6 in complex food matrices

Fluorescence spectroscopy for the detection of potentially malignant disorders of the oral cavity: analysis of 30 cases

Oral cancer is a major health problem worldwide and although early diagnosis of potentially malignant and malignant diseases is associated with better treatment results, a large number of cancers are initially misdiagnosed, with unfortunate consequences for long-term survival. Fluorescence spectroscopy is a noninvasive modality of diagnostic approach using induced fluorescence emission in tumors that can improve diagnostic accuracy. The objective of this study was to determine the ability to discriminate between normal oral mucosa and potentially malignant disorders by fluorescence spectroscopy. Fluorescence investigation under 408 and 532 nm excitation wavelengths was performed on 60 subjects, 30 with potentially malignant disorders and 30 volunteers with normal mucosa. Data was analyzed to correlate fluorescence patterns with clinical and histopathological diagnostics. Fluorescence spectroscopy used as a point measurement technique resulted in a great variety of spectral information. In a qualitative analysis of the fluorescence spectral characteristics of each type of injury evaluated, it was possible to discriminate between normal and abnormal oral mucosa. The results show the potential use of fluorescence spectroscopy for an improved discrimination of oral disorders.FAPESP/CePOF-CEPID (07/57126-5)CNPq (477439/2007-1)Instituto Nacional de Ciência e Tecnologia em Oncogenômica (INCITO

Detection of the peanut allergen Ara h 6 in foodstuffs using a voltammetric biosensing approach

A voltammetric biosensor for Ara h 6 (a peanut allergen) detection in food samples was developed. Gold nanoparticle-modified screen-printed carbon electrodes were used to develop a sandwich-type immunoassay using two-monoclonal antibodies. The antibody-antigen interaction was detected through the electrochemical detection of enzymatically deposited silver. The immunosensor presented a linear range between 1 and 100 ng/ml, as well as high precision (inter-day RSD ≤9.8 %) and accuracy (recoveries ≥96.7 %). The detection and quantification limits were 0.27 and 0.88 ng/ml, respectively. It was possible to detect small levels of Ara h 6 in complex food matrices

Desenvolvimento de um sensor de DNA impedimétrico para o diagnóstico de infecção por Papilomavirus Humano tipo 18

Currently, the most common strategy employed to detect DNA sequences is PCR (Polymerase Chain Reaction). Nevertheless, in the last few years research on DNA biosensors has increased significantly. Such sensors represent an alternative to PCR in the detection of specific DNA sequences, once they exhibit fast response, low limits of detection, and require simpler sample preparation. The development of a biosensor for detection of DNA from Human Papillomavirus type 18 is reported. To immobilise DNA probe onto indium-tin oxide (ITO) electrodes, a silanisation was carried out using 3-Aminopropyltryethoxysilane (APTES). Silanisation was studied and optimised using ultra-violet absorption spectroscopy, atomic force microscopy, fluorescence microscopy, and cyclic voltammetry. After immobilisation, the hybridisation with target sequence is detected by changes in surface properties of ITO electrode by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy, using the Ferri-Ferrocyante redox couple. The detection of synthetic target sequence was performed in the range of 12.5 to 100 nM, and 300nM for PCR products. The sensor did not show significative response for non-complementary sequence at 50 nM. This sensor can be applied for fast and low cost detection of HPV genetic material at nanomolar levels.A estratégia mais empregada atualmente na detecção de sequência de DNA é a PCR (Reação em Cadeira da Polimerase). Contudo, nos últimos anos, a pesquisa em biossensores de DNA tem aumentado significativamente. Estes sensores representam uma alternativa a PCR na detecção de sequências específicas de DNA, uma vez que exibem resposta rápida, baixos limites de detecção e requerem preparação simples da amostra. Nesta dissertação descrito o desenvolvimento de um biossensor para a detecção do DNA do Papilomavirus Humano tipo 18. A fim de imobilizar a sequência de captura de DNA em eletrodos de óxido de estanho e índio (ITO), realizou-se uma silanização usando 3-Aminopropiltrietoxisilano (APTES). A reação de silanização foi estudada e otimizada através das técnicas de Espectroscopia de Absorção Ultravioleta, Microscopia de Força Atômica, Microscopia de Fluorescência e Voltametria Cíclica. Após a imobilização, a hibridização com a sequência alvo é detectada através de alterações nas propriedades de superfície do eletrodo através de Voltametria Cíclica e Espectroscopia de Impedância Eletroquímica, usando o par redox Ferri-ferrocianeto. A detecção da sequência alvo sintética foi realizada no intervalo de 12.5 a 100 nM, e para o produto de PCR, 300 nM. O sensor não demonstrou resposta significativa para sequência não complementar a 50 nM. Este sensor pode ser aplicado na detecção rápida e de baixo custo de material genético do HPV a níveis nanomolares

Deposition Rate Influence in O3 Sensing Response of Sputtered ZnO Thin Films

The study of semiconductor materials applied as chemical gas sensing devices is currently focused on the production of new sensing materials with the best possible properties in terms of detection limits, selectivity, work temperature and response time. Although theoretical models show the great importance of film morphology on gas detection, a direct relation between structure size/morphology and the gas sensing properties has not been experimentally established. In this work, RF-sputtering deposition technique was used for the synthesis of zinc oxide thin films, and deposition conditions are variated to achieve a remarkable difference in nanostructure size of the material. The electrical resistance variation of the air-exposed films in presence of different ozone concentrations show a strong dependence on the feature size and film morphology, demonstrating the effectiveness of use the parameters of RF sputtering deposition as tunable factors to improve the ZnO sensing properties

Impedimetric immunosensors for the detection of Cry1Ab proteinfrom genetically modified maize seeds

Regardless the controversies surrounding genetically modified organisms (GMO), their cultivation isconstantly increasing and in according to the EU legislation, labeling is mandatory for products con-taining EU-authorized-GMO higher than 0.9%. Thereby, new analytical strategies for rapid and effectivedetection of GMO on foodstuffs are required. In this work, an electrochemical immunosensor foreffective determination of Cry1Ab protein from MON810 transgenic maize (EU-authorized-GMO) isdescribed. The immunosensor was developed onto indium tin oxide (ITO) electrodes modified by3-aminopropyltrimethoxysilane (APTES) monolayer to covalently immobilize Anti-Cry1Ab polyclonalantibodies. The protein interaction with the polyclonal antibody (PAb) recognition platform was directlymonitored and measured by cyclic voltammetry and electrochemical impedance spectroscopy usingcommercially Cry1Ab protein. After the analytical features optimization a linear response from 1 to10 ng mL−1, a limit of detection (LOD) of 0.37 ng mL−1and a limit of quantification (LOQ) of 1.23 ng mL−1– which provided accurate results (RSD < 7.5%) – were achieved. The immunosensor allowed a simple andfast detection of Cry1Ab protein extracted from maize seeds with different GM maize mass percentages(0%, 0.5%, 1%, 2.5% and 5%). To crosscheck the detection of Cry1Ab protein, an enzyme-linked immunosor-bent assay (ELISA) was used. The results indicate that the immunosensor is suitable for the transgenicprotein Cry1Ab detection in GM maize representing a successfully tool to verify the compliance of theEU regulations.info:eu-repo/semantics/publishedVersio