Enhancement of thermoelectric properties of La-doped SrTiO3 bulk by introducing nanoscale porosity

Electron-doped SrTiO3 is a well-known n-type thermoelectric material, although the figure of merit of SrTiO3 is still inferior compared with p-type metal oxide-based thermoelectric materials due to its high lattice thermal conductivity. In this study, we have used a different amount of the non-ionic surfactant F127 during sample preparation to introduce nanoscale porosities into bulk samples of La-doped SrTiO3. It has been observed that the porosities introduced into the bulk sample significantly improve the Seebeck coefficient and reduce the thermal conductivity by the charge carrier and phonon scattering respectively. Therefore, there is an overall enhancement in the power factor (PF) followed by a dimensionless figure of merit (zT) over a wide scale of temperature. The sample 20 at% La-doped SrTiO3 with 600 mg of F127 surfactant (SLTO 600F127) shows the maximum PF of 1.14 mW m−1 K−2 at 647 K which is 35% higher than the sample without porosity (SLTO 0F127), and the same sample (SLTO 600F127) shows the maximum value of zT is 0.32 at 968 K with an average enhancement of 62% in zT in comparison with the sample without porosity (SLTO 0F127)

Direct Production of Furfural in One-pot Fashion from Raw Biomass Using Brønsted Acidic Ionic Liquids

The conversion of raw biomass into C5-sugars and furfural was demonstrated with the one-pot method using Brønsted acidic ionic liquids (BAILs) without any mineral acids or metal halides. Various BAILs were synthesized and characterized using NMR, FT-IR, TGA, and CHNS microanalysis and were used as the catalyst for raw biomass conversion. The remarkably high yield (i.e. 88%) of C5 sugars from bagasse can be obtained using 1-methyl-3(3-sulfopropyl)-imidazolium hydrogen sulfate ([C 3 SO 3 HMIM][HSO 4 ]) BAIL catalyst in a water medium. Similarly, the [C 3 SO 3 HMIM][HSO 4 ] BAIL also converts the bagasse into furfural with very high yield (73%) in one-pot method using a water/toluene biphasic solvent system

Facile Synthesis of Palladium-Nanoparticle-Embedded N-Doped Carbon Fibers for Electrochemical Sensing

2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. In recent years, there have been many studies on metal/carbon hybrid materials for electrochemical applications. However, reducing the metal content in catalysts is still a challenge. Here, a facile synthesis of palladium (Pd) nanoparticle-embedded N-doped carbon fibers (Pd/N-C) through electropolymerization and reduction methods is demonstrated. The as-prepared Pd/N-C contains only 1.5wt% Pd. Under optimal conditions, bisphenolA is detected by using amperometry in two dynamic ranges from 0.1 to 10μm and from 10 to 200μm, and the obtained correlation coefficients are close to 0.9836 and 0.9987, respectively. The detection limit (DL) for bisphenolA is determined to be 29.44 (±0.77)nm

Influence of disorder on the in-field Jc of MgB2 wires using highly active pyrene

In this work, we report on significantly enhanced critical current density (Jc) in MgB2 superconductor that was easily obtained by doping with a hydrocarbon, highly active pyrene (C16H10), and using a sintering temperature as low as ∼ 600 °C. The processing advantages of the C16H10 additive include production of a highly active carbon (C) source, an increased level of disorder, and the introduction of small grain size, resulting in enhancement of Jc

Facile Synthesis of Palladium-Nanoparticle-Embedded N-Doped Carbon Fibers for Electrochemical Sensing

2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. In recent years, there have been many studies on metal/carbon hybrid materials for electrochemical applications. However, reducing the metal content in catalysts is still a challenge. Here, a facile synthesis of palladium (Pd) nanoparticle-embedded N-doped carbon fibers (Pd/N-C) through electropolymerization and reduction methods is demonstrated. The as-prepared Pd/N-C contains only 1.5wt% Pd. Under optimal conditions, bisphenolA is detected by using amperometry in two dynamic ranges from 0.1 to 10μm and from 10 to 200μm, and the obtained correlation coefficients are close to 0.9836 and 0.9987, respectively. The detection limit (DL) for bisphenolA is determined to be 29.44 (±0.77)nm

Evaluation of residual stress and texture in isotope based (MgB2)-B-11 superconductor using neutron diffraction

Magnesium diboride (MgB2) superconducting wires have demonstrated commercial potential to replace niobium-titanium (NbTi) in terms of comparable critical current density. Its higher critical temperature makes MgB2 wire suitable for liquid-helium-free operation. We recently reported boron-11 isotope-based low-activation Mg11B2 superconducting wire with decent critical current density appropriate for low-cost superconducting fusion magnets. In this study, we have mainly focused on the neutron diffraction technique to measure the residual stress in Mg11B2 superconducting wire for the first time. The residual stress state was given qualitative and quantitative interpretation in terms of micro- and macrostress generation mechanisms based on the isotropic model confirmed by neutron texture measurements. The relationship between the stress/strain state in the wire and the transport critical current density is also discussed. This investigation could pave the way to further enhancement of the critical current density of low-activation Mg11B2 superconducting wires suitable for next-generation fusion grade magnets

Evaluation of a solid nitrogen impregnated MgB2 racetrack coil

To develop powerful wind turbine generators using superconducting technology, high-performance superconducting racetrack coils are essential. Herein, we report an evaluation of a multifilamentary magnesium diboride (MgB2) conductor-based racetrack coil cooled and impregnated simultaneously by solid nitrogen (SN2). The coil was wound on a copper former with 13 mm winding width, an inner diameter of 124 mm at the curvature, and 130 mm length of the straight section. An in situ processed S-glass-insulated 36-filament MgB2 wire was wound on the former in two layers with 19.5 turns, and heat treated via the wind and react method without any epoxy resin. The coil was evaluated for critical temperature and transport critical current in the SN2 environment at different temperatures up to 31.3 K in self-field. The coil was able to carry 200 A transport current at 28.8 K in self-field. During coil charging and operation, SN2 effectively acted as an impregnation material. The test results demonstrate the viability to use MgB2 racetrack coil potentially with SN2 impregnation in advanced rotating machine applications

Enhanced Connectivity and Percolation in Binary and Doped in situ MgB2 Wires after Cold High Pressure Densification

The cold high pressure densification technique (CHPD) was recently developed in Geneva for improving the in-field critical current density of in situ binary and alloyed ¿¿ wires and tapes [1], [2]. of CHPD treated square wires alloyed with malic acid was enhanced by a factor 2 at 10 T and 4.2 K. In order to understand the fundamental mechanism behind this strong improvement of , the properties of binary and alloyed ¿¿ wires have been investigated without and with CHPD, using resistivity and specific heat measurements in the temperature range from 5 to 35 K in magnetic fields up to 15 T. In particular, a deconvolution of the specific heat data was used to determine the distribution of in the samples. We have found that the effect of the densification process on the electrical and transport properties is related to the improved grain connectivity and percolation. By combining the results arising from the analysis of the distribution and those from resistivity measurements, it is concluded that the minimum superconducting volume fraction needed for the percolation of a superconducting path is strongly reduced in samples treated by CHPD

Comparative analysis of extended aeration and Fenton process in landfill leachate treatment

This research is undertaken to investigate various operating conditions for minimising sludge disposal and maximising chemical oxygen demand from leachate. With conventional extended aeration process the optimum removal of COD and colour were 36% and 24% respectively. In Fenton process, for optimum pH of 5 and optimum H2O2/Fe2+ molar ratio of 1.3, the dosages of H2O2 and Fe2+ were found 1000 mg/l and 1250 mg/l, respectively. Under these conditions, the achievements for optimum COD and colour removal were 80% and 97%, respectively, while a combined treatment process of aeration followed by Fenton process resulted into higher COD and colour removals