Pyrite Biooxidation by Acidophilic Archaea AcidiplasmaSp. MBA-1 Under Varied Conditions

The goal of this research was to study pyrite (FeS2 ) bioleaching by a strain of the genus Acidiplasma under different conditions (temperature, pH) to evaluate the potential role of Acidiplasma representatives in biooxidation of this sulfide mineral. To compare the role of Acidiplasma archaea in pyrite biooxidation with other acidophilic microorganisms, the experiments were also performed with representatives of othergroups of microorganisms predominant in biohydrometallurgical processes.Pure and mixed cultures of moderately thermophilic acidophilic microorganisms, including strains Acidithiobacillus caldus MBC-1, Sulfobacillusthermosulfidooxidans VKMV 1269T and Acidiplasmasp. MBA-1, were used. The experiments were carried out in flasks with 100 mL of mineral nutrient medium supplemented with 0.02% yeast extract and 1 g of pyrite on a rotary shaker for 20 days. Bioleaching was performed at 45, 55, and 60∘С. The results demonstrated that the representatives of the genus Acidiplasmaprovided a comparatively higher rate of pyrite bioleaching at high temperatures (55 and 60∘C) and low pH of the medium (1.0). Thus, according to the results, strains of thegenus Acidiplasma may provide a high rate of pyrite bioleaching at low levels ofpH. Therefore, the results suggest that archaea of the genus Acidiplasma may be promising microorganisms to improve bioleaching processes with an increase in the operational temperature, which is usually maintained at 40–45∘C in industrial-scale reactors. Keywords: biomining, bioleaching, acidophilic microorganisms, sulfide minerals, pyrite

Electrospun ZnSnO3/ZnO Composite Nanofibers and Its Air-Sensitive Properties

In this work, a novel heterojunction based on ZnSnO3/ZnO nanofibers was prepared using electrospinning method. The crystal, structural and surface compositional properties of sample based on ZnSnO3 and ZnSnO3/ZnO composite nanofibers were investigated by X-ray diffractometer (XRD), Scanning electron microscope (SEM), X-ray photoelectron spectrometer (XPS) and Brunauer-Emmett-Teller (BET). Compared to pure ZnSnO3 nanofibers, the ZnSnO3/ZnO heterostructure nanofibers display high sensitivity and selectivity response with fast response towards ethanol gas at low operational temperature. The sensitivity response of sensor based on ZnSnO3/ZnO composite nanofibers were 19.6 towards 50 ppm ethanol gas at 225°C, which was about 1.5 times superior than that of pure ZnSnO3 nanofibers, which can be owed mainly to the presence of oxygen vacancies and the synergistic effect between ZnSnO3 and ZnO.

Development and Thermophysical Profile of Cetyl Alcohol-in-Water Nanoemulsions for Thermal Management

This study focuses on the preparation, thermophysical and rheological characterization of phase change material nanoemulsions as latent functionally thermal fluids. Aqueous dispersions with fine droplets of cetyl alcohol (with a melting temperature at ~321 K) were prepared by means of a solvent-assisted method, combining ultrasonication with non-ionic and anionic emulsifiers. Eicosyl alcohol (melting at ~337 K) and hydrophobic silica nanoparticles were tested as nucleating agents. Droplet size studies through time and after freeze–thaw cycles confirmed the good stability of formulated nanoemulsions. Phase change analyses proved the effectiveness of eicosyl alcohol to reduce subcooling to a few Kelvin. Although phase change material emulsions exhibited thermal conductivities much larger than bulk cetyl alcohol (at least 60% higher when droplets are solid), reductions in this property reached 15% when compared to water. Samples mainly showed desirable Newtonian behavior (or slight shear thinning viscosities) and modifications in density around melting transition were lower than 1.2%. In the case of phase change material nanoemulsions with 8 wt.% content of dispersed phase, enhancements in the energy storage capacity overcome 20% (considering an operational temperature interval of 10 K around solid–liquid phase change). Formulated dispersions also showed good thermal reliability throughout 200 solidification–melting cycles.

Impact of Temperature and Material Variation on Mechanical Properties of Parts Fabricated with Fused Deposition Modelling (FDM) Additive Manufacturing

Additive Manufacturing (AM) can be deployed for space exploration purposes, such as fabricating different components of robots’ bodies. The produced AM parts should have desirable thermal and mechanical properties to withstand the extreme environmental conditions, including the severe temperature variations on moon or other planets which cause changes in parts’ strengths and may fail their operation. Therefore, the correlation between operational temperature and mechanical properties of AM fabricated parts should be evaluated. In this study, three different types of polymers, including polylactic acid (PLA), polyethylene terephthalate glycol (PETG), and acrylonitrile butadiene styrene (ABS), were used in Fused Deposition Modeling (FDM) process to fabricate several parts. The mechanical properties of produced parts were then investigated at various temperatures to generate knowledge on the correlation between temperature and type of material. When varying the operational temperature during tensile tests, the material’s glass transition temperature was found influential in determining the type of material failure. Among the materials used, ABS showed the best mechanical properties at all temperatures due to its highest glass transmission temperatures. The results of statistical analysis indicated the temperature as the significant factor on tensile strength while the change in material did not show a significant effect.

Strategies to Facilitate Photovoltaic Applications in Road Structures for Energy Harvesting

Photovoltaic (PV) facilities are sustainable and promising approaches for energy harvesting, but their applications usually require adequate spaces. Road structures account for a considerable proportion of urban and suburban areas and may be feasible for incorporation with photovoltaic facilities, and thereby have attracted research interests. One solution for such applications is to take advantage of the spare ground in road facilities without traffic load, where the solar panels are mounted as their conventional applications. Such practices have been applied in medians and slopes of roads and open spaces in interchanges. Applications in accessory buildings and facilities including noise/wind barriers, parking lots, and lightings have also been reported. More efforts in existing researches have been paid to PV applications in load-bearing pavement structures, possibly because the pavement structures cover the major area of road structures. Current strategies are encapsulating PV cells by transparent coverings to different substrates to prefabricate modular PV panels in factories for onsite installation. Test road sections with such modular solar panels have been reported, where inferior cost-effectiveness and difficulties in maintenance have been evidenced, suggesting more challenges exist than expected. In order to enhance the power output of the integrated PV facilities, experiences from building-integrated PVs may be helpful, including a selection of proper PV technologies, an optimized inclination of PV panels, and mitigating the operational temperature of PV cells. Novel integrations of amorphous silicon PV cells and glass fiber reinforced polymer profiles are proposed in this research for multi-scenario applications, and their mechanical robustness was evaluated by bending experiments.

Analysis of Thermomechanical Stresses of a Photovoltaic Panel Using a Passive System of Cooling

In this paper, the gradient temperature and the thermomechanical stresses of a photovoltaic panel has been studied with and without heatsink. For this purpose, a three-dimensional analysis was carried out. Accordingly, a heat transfer analysis was developed. The numerical results show a cooling close to 26.7% with the proposed triangle fins compared with the rectangular fins studied before by another author, and the temperature distribution was determined. With this information, the stress analysis was carried out in order to find the effect on the panel due to the thermomechanical stresses. The aluminium frame was restricted to move freely. The resulting stresses field established the magnitude of the alternative stresses, resulting in a 6.7% drop compared with a reference panel. The guidelines of IEC 61215 have to be take into account. Due to the results obtained, the use of this kind of system in desert conditions is desirable because of its high operational temperature and due to the increase in heat transfer by the fins.

FABRICATION AND CHARACTERIZATION OF UHTCMCS

The materials currently used in aerospace and aviation, such as C/C and C/SiC composites, possess excellent mechanical properties but are limited to a maximum operational temperature of 1600°C (C/SiC) and poorly oxidizing environments (C/C). For more demanding applications, new materials able to withstand extreme temperatures without recession are required. In the framework of the C3harme project, a new class of materials labelled UHTCMCs, consisting of a UHTC matrix reinforced with carbon fibers, has been developed and characterized in order to overcome these challenges. Different fiber reinforcements and sintering parameters have been investigated from the microstructural point of view. The composites were fabricated via slurry infiltration of fiber, using a powder mixture of ZrB2 and SiC; the green pellets were then sintered via hot pressing. Extensive microstructural analysis was carried out on the sintered samples, showing how the sintering parameters and the choice of the fibers are crucial to obtain full densification without jeopardizing the fibers integrity and permit adequate load transfer.

Simulation and Optimization Studies of the LHCb Beetle Readout ASIC and Machine Learning Approach for Pulse Shape Reconstruction

The optimization of the Beetle readout ASIC and the performance of the software for the signal processing based on machine learning methods are presented. The Beetle readout chip was developed for the LHCb (Large Hadron Collider beauty) tracking detectors and was used in the VELO (Vertex Locator) during Run 1 and 2 of LHC data taking. The VELO, surrounding the LHC beam crossing region, was a leading part of the LHCb tracking system. The Beetle chip was used to read out the signal from silicon microstrips, integrating and amplifying it. The studies presented in this paper cover the optimization of its electronic configuration to achieve the lower power consumption footprint and the lower operational temperature of the sensors, while maintaining a good condition of the analogue response of the whole chip. The studies have shown that optimizing the operational temperature is possible and can be beneficial when the detector is highly irradiated. Even a single degree drop in silicon temperature can result in a significant reduction in the leakage current. Similar studies are being performed for the future silicon tracker, the Upstream Tracker (UT), which will start operating at LHC in 2021. It is expected that the inner part of the UT detector will suffer radiation damage similar to the most irradiated VELO sensors in Run 2. In the course of analysis we also developed a general approach for the pulse shape reconstruction using an ANN approach. This technique can be reused in case of any type of front-end readout chip.

High Response of Ethanol Gas Sensor Based on NiO-Doped Apple Pectin by the Solution Process

Novel gas sensor devices, based on biomaterial apple pectin film (APN) doped with NiO, were fabricated for the first time using a solution processing technique. The device was then annealed in a microwave chamber. The structural, elemental, and surface morphology of the device was investigated, using TEM, XPS, and AFM, respectively. The as-fabricated film sensor possessed a superior sensing performance regarding ethanol gas, compared to the pure apple pectin film sensor. The response of the device was recorded at a maximum efficiency of 161. For a 10 ppm concentration of ethanol gas at an operational temperature of 250 °C, the response time was 1.379 s. Nevertheless, the sensing mechanism for the sensor device is also described thoroughly.