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Item type:Publication, Rapid Scalable Processing of Tin Oxide Transport Layers for Perovskite Solar Cells(American Chemical Society, 2020-06-22)Abstract The development of scalable deposition methods for perovskite solar cell materials is critical to enable the commercialization of this nascent technology. Herein, we investigate the use and processing of nanoparticle SnO2 films as electron transport layers in perovskite solar cells and develop deposition methods for ultrasonic spray coating and slot-die coating, leading to photovoltaic device efficiencies over 19%. The effects of postprocessing treatments (thermal annealing, UV ozone, and O2 plasma) are then probed using structural and spectroscopic techniques to characterize the nature of the np-SnO2/perovskite interface. We show that a brief ?hot air flow? method can be used to replace extended thermal annealing, confirming that this approach is compatible with high-throughput processing. Our results highlight the importance of interface management to minimize nonradiative losses and provide a deeper understanding of the processing requirements for large-area deposition of nanoparticle metal oxides. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Synthesis and characterization of stiff, self-crosslinked thermoresponsive DMAA hydrogels(MDPI, 2020-06-01)Stiff thermosensitive hydrogels (HG) were synthesized by self-crosslinking free radical polymerization of N, N-dimethylacrylamide (DMAA) and N-isopropylacrylamide (NIPAAm), adjusting the degree of swelling by carboxylate-containing sodium acrylate (NaAc) or a 2-oxazoline macromonomer (MM). The formation of hydrogels was possible due to the self-crosslinking property of DMAA when polymerized with peroxodisulfate initiator type. The MM was synthetized by the ring-opening cationic polymerization of 2-methyl-2-oxazoline (MeOxa) and methyl-3-(oxazol-2-yl)-propionate (EsterOxa), and contained a polymerizable styryl endgroup. After ester hydrolysis of EsterOxa units, a carboxylate-containing MM was obtained. The structure of the hydrogels was confirmed by 1Hhigh-resolution (HR)-MASNMRspectroscopy. Suitable conditions and compositions of the comonomers have been found, which allowed efficient self-crosslinking as well as a thermoresponsive swelling in water. Incorporation of both the polar comonomer and the macromonomer, in small amounts furthermore allowed the adjustment of the degree of swelling. However, the macromonomer was better suited to retain the thermoresponsive behavior of the poly (NIPAAm) due to a phase separation of the tangling polyoxazoline side chains. Thermogravimetric analysis determined that the hydrogels were stable up to ~ 350 ffiC, and dynamic mechanical analysis characterized a viscoelastic behavior of the hydrogels, properties that are required, for example, for possible use as an actuator material.7 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Fabrication and luminescence properties in Yb–Tb co-doped a-SiCO thin films(VBRI Press, 2020-07-24)Amorphous silicon oxycarbide (a-SiCxOy) single doped with Yb3+ and co-doped with the couple Tb3+ - Yb3+ thin films were grown on crystalline silicon substrates by rf magnetron sputtering. The elemental composition in at. % is determined by energy dispersive spectroscopy and fourier transform infrared spectroscopy allows to investigate the chemical properties of the host. The concentration of Yb in the single doped sample was 3.5% and for the codoped samples (Yb, Tb) were (3%, 0.9%), (3.5%, 0.6%) and (4%, 0.6%), respectively. Post-deposition annealing treatments were made in order to induce optical activation of the rare earths. Conversion or absorption of high energy photons were analyzed by photoluminescence spectroscopy. The photoluminescence spectra show that for a given temperature range in the thermal annealing process, as well as for the appropriate rare earth concentrations the activation of Yb3+ and Tb3+ is enhanced. A strong reduction of the Tb3+ emission in contrast to the Yb3+ emission in the a-SiCxOy,:Tb:Yb samples at annealing temperature at 500°C suggests a energy transfer from Tb3+ to Yb3+ ions. Copyright © 2018 VBRI Press. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Strain and grain size of CeO2 and TiO2 nanoparticles: comparing structural and morphological methods(MDPI, 2021-06-07)Various crystallite size estimation methods were used to analyze X-ray diffractograms of spherical cerium dioxide and donut-like titanium dioxide anatase nanoparticles aiming to evaluate their reliability and limitations. The microstructural parameters were estimated from Scherrer, Monshi, Williamson-Hall, and their variants: i) uniform deformation model, ii) uniform strain deformation model, and iii) uniform deformation energy density model, and also size-strain plot, and Halder-Wagner method. For that, and improved systematic Matlab code was developed to estimate the crystallite sizes and strain, and the linear regression analysis was used to compare all the models based on the coefficient of determination, where the Halder Wagner method gave the highest value (close to 1). Therefore, being the best candidate to fit the X-ray Diffraction data of metal-oxide nanoparticles. Advanced Rietveld was introduced for comparison purposes. Refined microstructural parameters were obtained from a nanostructured 40.5 nm Lanthanum hexaboride nanoparticles and correlated with the above estimation methods and transmission electron microscopy images. In addition, electron density modelling was also studied for final refined nanostructures, and μ-Raman spectra were recorded for each material estimating the mean crystallite size and comparing by means of a phonon confinement model. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Development and validation of the mechanical behavior of a cervical disc implant with an “S” shape of Ti6Al-4V ELI manufactured by SLM(Universidad del Norte, 2021-01-21)Publicación de la División de Ingenierías de la Universidad del Norte. Ofrece a los sectores académico y productivo los desarrollos científicos y tecnológicos en esta área. La revista circula semestralmente. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Perspective chapter: optimal analysis for the correlation between vibration and temperature through an intelligent sensor/transducer based in amorphous nanostructures to measure vibrating surfaces temperature(IntechOpen, 2022-12-02)The vibration is an oscillatory movement caused by a propagation of waves through fluids or solids, and this consequence is achieved in many mechanic systems by the energy transmission between the movement source with the machine that needs the transmission movement, such as the vibration produced by a combustion engine, by a compressor system and by a result of movement transmission over rotor systems. However, if it is not a controlled mechanism to moderate the produced decibels, the main system that is affected by the vibration can reduce its performance; moreover, it can increase the surface temperature of the vibrating source and systems around. In spite of this, when it uses contact sensors to measure the vibration and temperature over the surface vibrating system, the measured data are under disturbance caused by the vibration source. Therefore, in this research is proposed an intelligent sensor/transducer based in amorphous nanostructures owing to measure the vibration of the surface through infrared (IR) emitter/receiver and the absorbance of the receiver sample has a quite range of work and robustness under disturbance of vibrating signals. This proposed sensor also has the possibility to charge energy by itself because of sun/warmth energy conversion. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Highly porous seeding-free boron-doped ultrananocrystalline diamond used as high-performance anode for electrochemical removal of carbaryl from water(Elsevier BV, 2022-06-25)Boron-doped diamond (BDD) electrodes are regarded as the most promising catalytic materials that are highly efficient and suitable for application in advanced electrochemical oxidation processes targeted at the removal of recalcitrant contaminants in different water matrices. Improving the synthesis of these electrodes through the enhancement of their morphology, structure and stability has become the goal of the material scientists. The present work reports the use of an ultranano-diamond electrode with a highly porous structure (B-UNCD WS /TDNT/Ti) for the treatment of water containing carbaryl . The application of the proposed electrode at current density of 75 mA cm −2 led to the complete removal of the pollutant (carbaryl) from the synthetic medium in 30 min of electrolysis with an electric energy per order of 4.01 kWh m −3 order −1 . The results obtained from the time-course analysis of the carboxylic acids and nitrogen-based ions present in the solution showed that the concentrations of nitrogen-based ions were within the established maximum levels for human consumption. Under optimal operating conditions, the proposed electrode was successfully employed for the complete removal of carbaryl in real water. Thus, the findings of this study show that the unique, easy-to-prepare BDD-based electrode proposed in this study is a highly efficient tool which has excellent application potential for the removal of recalcitrant pollutants in water. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Estudos decoloniais nos circuitos hegemônicos da produção acadêmica brasileira(Fundação Getulio Vargas, Escola Brasileira de Administração Pública e de Empresas, 2024-01-01)Resumo Em que medida a circulação contemporânea de teorias que questionam ontologias coloniais e reivindicam renovação crítica para o pensamento latino-americano influenciou o desenvolvimento de novas agendas de pesquisa no Brasil? Este artigo dirige-se aos circuitos hegemônicos da produção do conhecimento acadêmico brasileiro para compreender o impacto das perspectivas decoloniais durante a primeira década de recepção e apropriação dessa teoria pela produção intelectual do país. Por meio de um mapeamento de 246 artigos que abordaram os termos “decolonial” ou “decoloniais” publicados até 2018, procuramos analisar diferentes usos que a categoria adquiriu em pesquisas brasileiras. O objetivo foi descrever a configuração de redes de estudos decoloniaisj com base na revisão bibliométrica dessa literatura, com a intenção de apresentar um quadro histórico parcial dos principais temas, autores, autoras e bibliografias que foram mobilizados em periódicos registrados nas bases de dados Scopus e Web of Science entre 2009 e 2018. Os resultados desta investigação sugerem que estudos identificados com perspectivas decoloniais apresentaram-se como investigações simultaneamente analíticas e políticas, que se organizavam em torno do campo disciplinar das ciências sociais, mas com impacto visível em outras áreas do conhecimento. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A superhydrophobic and supercapacitive nanocoating: Reduced graphene oxide/fluoropolymer applied on PET fabric by spray mist coating(RELX Group (Netherlands), 2024-01-01) - Some of the metrics are blocked by yourconsent settings
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