High-throughput fabrication of carbonized electrospun polyacrylonitrile/poly(acrylic acid) nanofibers with additives for enhanced electrochemical sensing

Lightweight, polyacrylonitrile-derived electrodes with different additives were fabricated using high-throughput nozzle-free electrospinning. The electrospun precursor nanofibers (PNFs) containing iron oxide, gold nanoparticles, or reduced graphene oxide (rGO) were subjected to oxidative stabilization and carbonization to obtain a carbon-rich conductive nanofiber structure. Scanning electron microscopy showed that the carbon nanofibers contracted between 11 and 55% while the Fourier-transform infrared spectroscopy confirmed that the carbon nanofibers were thermally stable. Thermogravimetric and differential scanning calorimetry results revealed that the cross-linking of the chain molecules and cyclization were completed. Next, cyclic voltammetry results indicated that the electroactivity of the modified screen-printed carbon electrodes was decreased by 85% due to the presence of carbon glue. The modified device presented significant enhanced electrochemical responses with the inclusions of nanoparticles, with rGO showing a 2.13 times higher electroactive surface area, followed by iron oxide (two times) and gold nanoparticles (1.37 times) than the equivalent PNFs.     

Most Recent Changepoint Detection in Panel Data

Detecting recent changepoints in time-series can be important for short-term prediction, as we can then base predictions just on the data since the changepoint. In many applications, we have panel data, consisting of many related univariate time-series. We present a novel approach to detect sets of most recent changepoints in such panel data that aims to pool information across time-series, so that we preferentially infer a most recent change at the same time-point in multiple series. Our approach is computationally efficient as it involves analysing each time-series independently to obtain a profile-likelihood like quantity that summarizes the evidence for the series having either no change or a specific value for its most recent changepoint. We then post-process this output from each time-series to obtain a potentially small set of times for the most recent changepoints, and, for each time, the set of series that has their most recent changepoint at that time. We demonstrate the usefulness of this method on two datasets: forecasting events in a telecommunications network and inference about changes in the net asset ratio for a panel of US firms.     

Tag-less back-translation

An effective method to generate a large number of parallel sentences for training improved neural machine translation (NMT) systems is the use of the back-translations of the target-side monolingual data. The standard back-translation method has been shown to be unable to efficiently utilize huge amounts of existing monolingual data because of the inability of translation models to differentiate between authentic and synthetic parallel data during training. Tagging, or using gates, has been used to enable translation models to distinguish between synthetic and authentic data, improving standard back-translation and also enabling the use of iterative back-translation on language pairs that underperformed using standard back-translation. In this work, we approach back-translation as a domain adaptation problem, eliminating the need for explicit tagging. In our approach—tag-less back-translation—the synthetic and authentic parallel data are treated as out-of-domain and in-domain data, respectively, and through pre-training and fine-tuning, the translation model is shown to be able to learn more efficiently from them during training. Experimental results have shown that the approach outperforms the standard and tagged back-translation approaches on low resource English-Vietnamese and English-German NMT.

     

Physicochemical Properties and Sensory Attributes of Medium- and Long-Chain Triacylglycerols (MLCT)-Enriched Bakery Shortening

Six binary formulations of medium- and long-chain triacylglycerols (MLCT) fat and palm stearin and four ternary formulations of MLCT fat, palm stearin, and palm olein were produced. MLCT fat and palm stearin were mixed in ranges of 40–90% with 10% increments (w/w), while for the ternary formulations, 10% and 20% palm olein were substituted to palm stearin in MS 46 and MS 55 formulations. The solid fat content (SFC) by pulsed nuclear magnetic resonance and heating profiles using differential scanning calorimeter of these formulations were determined. Results obtained from SFC and heating profiles found that all the formulations melted completely at 55 °C. The high complete melting temperature is due to the stearic acid content in MLCT fat. Generally, increasing % MLCT fat (40–90%) in the formulations lowers the SFC curves at the measured temperatures (0–60 °C). The binary samples of MS 73, MS 82, and MS 91 showed SFC between 15% and 25% at room temperature (25 °C), which indicated that these formulations were suitable for shortening production. As the production cost of MLCT fat is high (approximately USD 3/kg), an attempt to reduce the proportion of MLCT fat in the shortening formulations was done by developing the ternary formulations. Shortenings formulated with 40:40:20 (MSO 442), 50:40:10 (MSO 541), and 50:30:20 (MSO 532) of MLCT fat/palm stearin/palm olein formulations had similar SFC% at 25 °C, and they were subsequently chosen to produce shortening. Using multivariate analysis, taste attribute showed positively and highly correlated to the melting temperature and SFC at 25 °C of the MLCT-enriched shortenings. In acceptance test, high correlation (R ² = 0.98) was only found on cakes made from MSO 442 and MSO 541 shortenings. Both untrained and trained panelists rated the Madeira cakes made from MSO 532 shortening the highest for overall acceptability.     

Recovery of neutron-irradiation-induced defects of Al2O3, Y2O3, and yttrium-aluminum garnet

SiC fiber-reinforced SiC matrix composites (SiC_f/SiC) are considered as one of the candidates for blanket materials in future fusion reactors and as an advanced fuel cladding material for next-generation fission reactors. Generally, the densification of SiC needs sintering additives and oxides such as Al₂O₃, Y₂O₃, and yttrium-aluminum garnet (YAG, Y₃Al₅O₁₂), which are frequently added to SiC. However, the effects of neutron irradiation on sintering additives are still unclear. In this study, we performed the neutron irradiation of Al₂O₃, Y₂O₃, and YAG at fluences up to 2.0–2.5 × 10²⁴ n/m² (E > 0.1 MeV) at 60–90 °C. The isochronal recovery of the macroscopic volume of Al₂O₃ against annealing temperature showed smooth and continuous shrinkage at a temperature of up to 1200 °C, and the volume slightly increased above that temperature. In contrast, the volume of Y₂O₃ showed quick shrinkage at the low temperature range, and slower and smooth recovery was observed up to ～1100 °C. In the case of YAG, the recovery of volume occurred in a step-wise manner at 600–750 °C, and continuous shrinkage occurred at temperatures lower and higher than that temperature range. The activation energies for the macroscopic volume recoveries of three oxides were obtained from the Arrhenius plots of the rate coefficients. Two-stage recovery was observed for Al₂O₃, whereas more complicated recovery processes were suggested for Y₂O₃ and YAG.     

Enhancement of Thermoelectric Behavior of La0.5Co4Sb12−x Te x Skutterudite Materials

Metallurgical and Materials Transactions A - In this work, the effects of Te doping on the microstructure and thermoelectric properties of the partially filled skutterudite La0.5Co4Sb12 compounds...     

Microwave-induced pyrolysis of waste truck tyres with carbonaceous susceptor for the production of diesel-like fuel

Microwave-induced pyrolysis technique was utilised to pyrolyse waste truck tyres (TT) into useful pyrolysis oil with the aid of activated carbon. The effect of temperature was studied to determine the truck-tyre pyrolysis oil (TTPO) yield, hydrocarbon fractions, chemicals composition, energy yield and fuel properties. The activated carbon functions as microwave absorber to elevate the pyrolysis temperature for enhancing production of pyrolysis oil. The optimal pyrolysis temperature of 500 °C produces highest TTPO yield of 38.12 wt% with calorific value of 42.39 MJkg^?1 and energy yield of 40.55 wt%. Detailed analysis shows the TTPO contained large amount of aromatic hydrocarbons and limonene (14.29%) compared to pyrolysis oil from personal car tyre. Among the important chemical compounds also discovered in TTPO are benzene, toluene, xylene (BTX). The relative yields of toluene obtained at 400 °C is 14.85%, whereas the relative yields of benzene and xylene at 450 °C were 0.85 and 7.60%, respectively. The physiochemical properties of TTPO500 are rather similar to conventional diesel, except the slightly lower flash point and calorific value for the former. This work shows that microwave-induced pyrolysis is a promising technique to recover diesel-like fuel for use as supplemental alternative fuel.     

Physicochemical characteristics of soybean oil, palm kernel olein, and their binary blends

Soybean oil (SBO), palm kernel olein (PKO) and their binary blends (containing 5–40% PKO) were studied for their physicochemical characteristics. Decreases in band absorbencies of the resultant Fourier transform infrared spectra were observed in regions attributable to vibrations of the functional groups of unsaturated fatty acids, mainly the =C–H cis stretching at 3009 cm⁻¹and –C=C cis stretching at 1657 cm⁻¹. The solid fat content was measurable in the blends containing 15–40% PKO at 5 and 10 °C, ranging within 4–20% and 2–13%, respectively. The differential scanning calorimetry melting curve for SBO exhibited more complex transition peaks, suggesting a     polymorphic transformation when compared with PKO with a simpler     . Blending of SBO with PKO reduced the complexity caused by the polymorphic transformation, featuring the endotherms that only related to the β' fat crystals.     

Characteristics of slag produced from incinerated hospital waste

Ash produced from a hospital waste incinerator was treated using a high temperature melting process at 1200 degrees C. The quality of the produced slag was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), leaching tests and sequential chemical extraction of metals. The slag contained large amounts of SiO(2,) CaO, Al(2)O(3), Sn, Ni, Cu, Ba and B. XRD analysis revealed a moderate crystal structure for the melted slag and identified the main crystals as quartz (SiO(2)), kaolinite (Al(2)Si(2)O(5)(OH)(4)), albite (NaAlSi(3)O(8)) and gibbsite (Al(OH)(3)). The observed crystal structure assists in preventing the leaching of heavy metals from the slag. Furthermore, the leaching results found the produced slag to comply with disposal limits set by the US EPA. Results from sequential chemical extraction analysis showed that metals in the slag exhibited the strongest preference to be bound to the residual fraction (stable fraction), which is known to have very low leaching characteristics. Melting was found to stabilize heavy metals in hospital waste successfully and therefore it can be an acceptable method for disposal.