Three-dimensional printing techniques have been widely used in the fabrication of new materials applied to energy, sensing and electronics due to unique advantages, such as fast prototyping, reduced ...waste generation, and multiple fabrication designs. In this paper, the production of a conductive 3D-printing filament composed of Ni(OH)2 microparticles and graphene within a polylactic acid matrix (Ni-G-PLA) is reported. The nanocomposite was characterized by thermogravimetric, energy-dispersive X-ray spectroscopic, scanning electronic microscopic, Raman spectroscopic and electrochemical techniques. Characteristics such as printability (using fused deposition modelling), electrical conductivity and mechanical stability of the polymer nanocomposite were evaluated before and after 3D printing. The novel 3D-printed disposable electrode was applied for selective detection of glucose (enzyme-less sensor) with a detection limit of 2.4 μmol L−1, free from the interference of ascorbic acid, urea and uric acid, compounds typically found in biological samples. The sensor was assembled in a portable electrochemical system that enables fast (160 injection h−1), precise (RSD < 5%) and selective determination of glucose without the need of enzymes (electrocatalytic properties of the Ni-G-PLA nanocomposite). The obtained results showed that Ni-G-PLA is a promising material for the production of disposable sensors for selective detection of glucose using a simple and low-cost 3D-printer.
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•Production of a conductive 3D-printing filament composed by nickel microparticles and graphene within a PLA matrix.•Fast 3D printing of disposable electrodes for selective detection of glucose (enzyme-less sensor).•Single step fabrication of electrodes modified with nickel nanoparticles.•Direct printing of modified electrodes.
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•Nickel ferrite nanoparticles prepared by proteic sol–gel method as a energy storage eletrodes.•Capacitance enhancement by magnetic fields.•Magnetocapacitance in iron oxides.
Due to ...their differentiated structure and properties, nanoporous metals gain great attention in several areas, such as catalysis and energy storage. The effects of magnetic fields on electrochemical processes affect the theoretical and practical performance of the capacitors. This work describes the effect of a external magnetic field on the electrochemical performance of nickel ferrite nanoparticles prepared by the proteic sol–gel method. Here the electrochemical capacitance and the cyclability of the electrodes modified by the NiFe2O4 nanoparticles are compared without the intervention of any magnetic field and with the presence of a magnetic field of 200 mT flow density. Our experimental data showed that the studied material under an external magnetic field has a much better electrochemical performance when compared with the one without the application of a magnetic field. A magnetic field can improve the capacitance, reduce the charge transfer resistance and enhance the discharge performance. The improvement in the capacitance of the magnetized electrode increases 29.3 % in the current density of 1 A g−1, and the cyclability increases around 69.1 % when compared to the tested electrode without the magnetic field. Therefore, our results show an alternative way to improve the electrochemical performance of energy storage materials.
The increase in demand for both fast and inexpensive prototyping of objects, with a certain degree of resilience and durability, is the main reason why 3D printing has become part of the concept of ...industry 4.0 and it is omnipresent in research facilities and industries around the world. In this work, we describe step-by-step the construction process of a filament winder that can be adapted for many commercially available bench-size polymer extruders. The electronic circuit used to regulate the winding rate, and therefore the thickness of the filament, is completely based on simple open-code microcontrollers such as Arduino Uno. Finally, it is showed that using this system it is possible to obtain printable ABS filaments with a wide range of thicknesses and a margin of error of around 5%.
Applications in electronics and photonics have spurred research on new electronic and optical materials, including organic chromophores. In this work, we synthesized and characterized five compounds ...(4 of which novel) containing the 1,3,4-oxadiazole group. Four of the molecules contain one oxadiazole moiety connected on one side to a phenylene bridge and an aliphatic tail, while the other side terminates with either a thiophene or a pyridine group. The fifth molecule features an additional phenylene and oxadiazole group separating the core from its thiophene terminus. DFT calculations were used to investigate the photophysical properties of the molecules. The calculated excitation energy reflected well the trend observed in the UV–Vis spectra. The calculated first hyperpolarizability (β(0)) increased as the pyridine groups replaced the thiophenes. Extending the π-conjugated bridge did increase β in comparison to the shorter analog (both with the 2-thiophenyl end group), probably due to decreasing bandgap and excitation energy. Still, the highest β(0) found was for the compound containing the 4-pyridyl end group (Oxa-4-Py, 24.0 × 10−30 e.s.u.), suggesting that the appropriate end group might overcome the effect of extending π-conjugation.
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The development of efficient, robust, and low-cost electrocatalysts for the oxygen evolution reaction (OER) under mild conditions is a sustainable pathway for energy conversion and storage ...technologies. Cobalt Prussian blue analogue (Co-PBA) has been emerging as a potential candidate to be engineered and match such requirements. In this study, the catalytic activity performance of Co-PBA was improved by depositing over different types of graphene-based materials that act as supports, resulting in hybrid composites. The Co-PBA + r_GO N2, which is Co-PBA deposited over a reduced graphene oxide doped with N atoms (urea as N source), showed the best OER catalytic improvements in a neutral medium (0.5 mol L
−1
KNO
3
), reducing the overpotential in 54 mV and 137 mV to reach current densities of 10 (
J
10
) and 50 (
J
50
) mA cm
−2
, respectively, in comparison to the sole electrocatalyst Co-PBA. These results indicate that the interaction between the Co-PBA and graphene-based supports plays a pivotal role in effectively enhancing the OER activity of the electrocatalyst.
Graphene-based materials doped with N can act as supports to boost the electrocatalytic activity of Co-Prussian Blue in the oxygen evolution reaction (OER) under mild conditions.
ATLANTIC BIRDS Hasui, Érica; Metzger, Jean Paul; Pimentel, Rafael G. ...
Ecology (Durham),
02/2018, Volume:
99, Issue:
2
Journal Article
Peer reviewed
Open access
South America holds 30% of the world’s avifauna, with the Atlantic Forest representing one of the richest regions of the Neotropics. Here we have compiled a data set on Brazilian Atlantic Forest bird ...occurrence (150,423) and abundance samples (N = 832 bird species; 33,119 bird individuals) using multiple methods, including qualitative surveys, mist nets, point counts, and line transects). We used four main sources of data: museum collections, online databases, literature sources, and unpublished reports. The data set comprises 4,122 localities and data from 1815 to 2017. Most studies were conducted in the Florestas de Interior (1,510 localities) and Serra do Mar (1,280 localities) biogeographic sub-regions. Considering the three main quantitative methods (mist net, point count, and line transect), we compiled abundance data for 745 species in 576 communities. In the data set, the most frequent species were Basileuterus culicivorus, Cyclaris gujanensis, and Conophaga lineata. There were 71 singletons, such as Lipaugus conditus and Calyptura cristata. We suggest that this small number of records reinforces the critical situation of these taxa in the Atlantic Forest. The information provided in this data set can be used for macroecological studies and to foster conservation strategies in this biodiversity hotspot. No copyright restrictions are associated with the data set. Please cite this Data Paper if data are used in publications and teaching events.
Aim: To offer a test of expert knowledge about rarity of twenty Amazon forest bird species following an approach that equates rarity with low site occupancy and formally accounts for imperfect ...species detection. We define ten pairs of closely related species, each pair with one hypothetically common and one hypothetically rare species. Our null hypothesis is that members of each pair have similar occupancy, with hypothesized differences due to detection errors alone. Location: A 1000-ha plot of primary rainforest in the central Brazilian Amazon. Methods: We visited each of 55 sampling sites multiple times per season for three field seasons and estimated the probability of site occupancy by each species following a maximum likelihood state-space approach that also estimates the probability that a species is present yet undetected at a site. To maximize detection and account for its variation, we employed three different sampling techniques while systematically training and testing observer's ability to recognize species. Results: Occupancy estimates agree with expert predictions in all but two species pairs and show no evidence of clear temporal variation in occupancy between sampling seasons. Detection probability had a positive relation with observer ability, a strong relation to time of day across species, and a strong relation with the use of playback for some species. Detection with point counts and with autonomous recorders varied between species pairs. Main conclusions: We reject the null hypothesis of equal occupancy within pairs, concluding that expert knowledge on species rarity is useful and worth eliciting. Our results replace qualitative ratings of rarity with statistical estimates of occupancy, establishing a reliable baseline for future comparisons. Besides illustrating the relevance of expert knowledge, this application to Amazonian birds illustrates a flexible approach that can be used for testing knowledge about rarity for a variety of species groups and spatial scales.
An actinobacterial strain, designated SO9-6, was isolated from a copper iron sulfide mineral. The organism is Gram-positive, facultatively anaerobic, and coccoid. Chemotaxonomic and phylogenetic ...properties were consistent with its classification in the genus Kocuria. Here, we report the first draft genome sequence of Kocuria marina SO9-6 under accession JROM00000000 (http://www.ncbi.nlm.nih.gov/nuccore/725823918), which provides insights for heavy metal bioremediation and production of compounds of biotechnological interest.
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