Navegando por Assunto "Nanotechnology"

Agora exibindo 1 - 5 de 5

Acesso aberto (Open Access)
Análise de estruturas planares em THz baseadas em grafeno
(Universidade Federal do Pará, 2016-01-28) NASCIMENTO, Clerisson Monte do; DMITRIEV, Victor Alexandrovich; http://lattes.cnpq.br/0684541646225359
In this work we analyse the properties of scattering of electromagnetic waves in graphene surfaces and the planar plasmonic based devices made of the same material, both in THz frequency region. The work is presented in form of four scientific papers. In the first one a numerical analysis of the plasmonic waves propagation in graphene elements is performed. The influence of geometrical configuration, chemical potential variation, angle of incidence and polarizations is analysed. That results give us the information to project two devices (the second and third) based on frequency selective surfaces (FSS) on THz range and that are composed only by graphene elements and dielectric substrates without the insertions of different metals. The first device consists in a THz electromagnetic filter made by an planar array of graphene ring-shaped elements placed in both sides of a dielectric substrate. The second device presents new multifunctional graphene device that can operate either as an electromagnetic, dynamically controlled, filter or as an eletromagnectic switch. Both devices operates based on Fano resonance effect. The fourth paper presents a new method of analysis of periodic planar structure, based on group theory approach. This method takes account the transversal and longitudinal components of induced current in the structure. By using this, one can obtain more information about the device properties than by using exitenting methods, which uses only longitudinal components of the induced currents. As application, we suggest an analyse a periodic array of graphene elements.
Acesso aberto (Open Access)
Um estudo sobre a influência de defeitos de diferente natureza nas propriedades eletrônicas de nanotubos usando o método das ondas cilindricas linearizadas aumentadas
(Universidade Federal do Pará, 2014-12-12) GOMES, Fernando Antonio Pinheiro; PELAES, Evaldo Gonçalves; DMITRIEV, Victor Alexandrovich; http://lattes.cnpq.br/0684541646225359
The carbon and boron nitride nanotubes are one-dimensional structures which exhibit behavior both as metallic and semiconductor, depending on their chirality, except for the nanotubes of boron nitride which always have semiconductor characteristics, for pristine nanotubes. Due to their electronic characteristics, the nanotubes have great potential for application in nanoelectronic devices, such as nanodiodes, nanotransistors, interconnection elements, etc. For this reason, it is important to understand how external factors influence on the properties of such materials. One such factor is the introduction of external defects in the nanotubes. Such defects are the absence of one or more carbon atoms belonging to carbon nanotube and nitrogen or boron for boron nitride nanotubes, or the substitution of carbon, nitrogen or boron atoms by different ones in the structure of the corresponding nanotubes. This work presents a theoretical study of the effects of the introduction of a substitutional defects in the electronic properties of carbon and boron nitride nanotubes, via ab-initio simulation. The energy band and density of states structures was evaluated for both semiconducting and metallic carbon nanotube armchair and zig-zag types respectively and for boron nitride nanotube only armchair type using the method LACW - linearized augmented cylindrical waves. Furthermore, due to the boron nitride nanotubes are growing in importance, we make an additional systematic study of the electronic structure for these nanotubes, for a super cell formed by three unit cells, using intrinsic doping as well as quantitative analysis about relative stability based on the total energy and band gap value of these structures.
Acesso aberto (Open Access)
Interações de Quantum Dot com estruturas externas de vírus Nipah utilizando docking e dinâmica molecular
(Universidade Federal do Pará, 2023-01-30) ALMEIDA, Aguinaldo Pantoja de; OLIVEIRA, Mozaniel Santana de; http://lattes.cnpq.br/0810227136654245; HTTPS://ORCID.ORG/0000-0002-4076-2443; CHAVES NETO, Antônio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; https://orcid.org/0000-0002-9730-3512
Performing the interaction of the outermost protein of the Nipah virus with fourteen structures with possible potential for the emission of quantum dots, using anchoring and molecular dynamics, using molecular docking platforms: CB Docking, Swiss DOCK, AutoDock Vina 4.2.6 to perform a comparison of results explaining the best values, in addition to using Gromacs 2022 to make ligand trajectories in relation to time. The mostly hydrophobic complexes at the receptor binding site. The tolerance energy results tolerated the partial loads of the tips which showed better stability, the RMSD results also respected this premise. Thus, the set formed by combining proteins with a quantum dot has the potential to more efficiently adsorbing of the protein components of the virus. Molecular dynamics and docking studies and verification of binding energy revealed strong and stable binding between para QD K and QD-G and QD-F with the macrostructure of NIPAH virus. It was established in the docking studies, that the binders have emission energy scores of -13,658 kcal/mol, -13.6 kcal/mol, -13.9 kcal/mol, for K, G and F respectively. The same result was applied in the Gibbs free energy verification study with values for F of 239.00 kcal/mol, G of 246.65 kcal/mol and K of 259.52 kcal/mol.
Acesso aberto (Open Access)
Nanotecnologia: a revolução silenciosa na segurança do trabalho
(Universidade Federal do Pará, 2023-09-28) ALMEIDA, Patrícia do Socorro Pereira Macêdo; DEL NERO, Jordan; http://lattes.cnpq.br/5168545718455899
A pesquisa exploratória tem como objetivo analisar a regulamentação existente em relação à nanotecnologia e seu impacto na segurança dos trabalhadores. O estudo se concentrará em examinar os desafios específicos associados à nanotecnologia, incluindo a falta de dados toxicológicos adequados para avaliar os riscos, a complexidade da caracterização dos nanomateriais e as limitações das técnicas de monitoramento existentes. Um dos principais desafios enfrentados é a falta de dados suficientes sobre os efeitos à saúde dos trabalhadores expostos a nanomateriais. A nanotecnologia é uma área relativamente nova, e ainda há muito a ser aprendido sobre os possíveis efeitos adversos à saúde que esses materiais podem causar. A falta de dados toxicológicos adequados dificulta a avaliação precisa dos riscos e a implementação de medidas de proteção eficazes. Além disso, a caracterização dos nanomateriais também é uma tarefa complexa. Suas propriedades físicas e químicas únicas exigem métodos de análise especializados e técnicas avançadas. A falta de padronização nesse campo dificulta a compreensão completa dos nanomateriais e sua relação com os efeitos à saúde. Outro desafio é a limitação das técnicas de monitoramento disponíveis para avaliar a exposição dos trabalhadores a nanomateriais. Os métodos tradicionais de monitoramento podem não ser adequados para detectar e quantificar a presença de nanomateriais no ambiente de trabalho, devido ao seu tamanho diminuto e às suas propriedades únicas. Isso dificulta a avaliação precisa da exposição dos trabalhadores e a implementação de medidas de controle apropriadas. O estudo também se propõe a examinar as estratégias e abordagens adotadas por diferentes países e organizações internacionais para enfrentar esses desafios e garantir a segurança dos trabalhadores expostos à nanotecnologia. Isso pode incluir o desenvolvimento de regulamentações específicas, a promoção de pesquisas e estudos toxicológicos, a criação de diretrizes de boas práticas e a implementação de medidas de controle de engenharia e proteção individual. Em resumo, a pesquisa exploratória visa analisar a regulamentação existente e os desafios relacionados à segurança dos trabalhadores na área da nanotecnologia. Compreender e abordar esses desafios é essencial para garantir a proteção dos trabalhadores e promover o uso seguro e responsável da nanotecnologia na indústria.
Acesso aberto (Open Access)
Prototipagem de sistema de alarme de incêndio baseado em sensor nanoestruturado integrado a IoT
(Universidade Federal do Pará, 2021-06-29) FREITAS, Luís Gustavo Oliveira de; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637
The improvement of remote sensing systems for the detection of forest fires or industrial plants is fundamental to the development of industry 4.0, and it is becoming increasingly important for many countries where forest fires occur frequently. Therefore, it is necessary to design and explore a device that has a quick response, that has remote monitoring in real time and can generate warning signs that precede major fires in indoor (indoor) and outdoor (outdoor) environments, this nanostructured sensor based on buckypaper that it consists of carbon nanotube films and has thermal sensitivities that can be measured in short response times. In the prototyping of the fire alert sensor, thermal tests were carried out to evaluate the effectiveness. Furthermore, it was integrated with IoT (Internet of Things) using the NodeMCU architecture together with the MQTT (Message Queuing Telemetry Transport) protocol, thus enabling the sending of the alert message to the end user through an Android application. Preliminary results show that this nanostructured sensor can be effective at distances of less than 1 meter from the fire source, for example at 20 cm, generating a thermovoltage of 2.3 mV over 80 seconds with a heat source at 240 ° C. This work shows the entire development process of this prototype with real-time monitoring with the function of issuing an early fire alert.