Electrical and Thermal Conduction Behaviors in La‐Substituted GdBaCuFeO5+δ Ceramics

Gd_1?xLa_xBaCuFeO_5+δ polycrystalline ceramics have been prepared by a sol–gel method combined with the traditional ceramic processing. Analysis of the microstructure and phase composition reveals that the pure GdBaCuFeO_5+δ phase can be obtained even after the substitution of 50% La at Gd‐site. The band gap can be tuned from 1.47 to 1.36 eV by La substitution, resulting in a significant increase in the electrical conductivity. In addition, the total thermal conductivity can also be suppressed by the substitution of La at Gd‐sites. A ZT value of 0.02 at 1023 K is achieved in the 50% La‐substituted samples, which is over 20 times higher than that of the pure GdBaCuFeO_5+δ sample.     

Nonisothermal analysis of a couple stress fluid in blade coating process

In this paper, a nonisothermal analysis for the process of blade coating of an incompressible couple stress fluid is presented using both plane and exponential coaters. The governing system is simplified using lubrication approximation theory (LAT). The interesting quantities from engineering point of view like normalized pressure, maximum pressure, pressure gradient, velocity, and effects of involved parameters on temperature distribution, which influence the coating process are evaluated. It is observed that pressure is at maximum near the edge of the blade whereas fluid velocity and temperature are at maximum near the substrate. An increasing couple stress parameter increases the load and decreases the coating thickness. It is worth mentioning that load and pressure are the most significant outcomes of the present exertion as these two physical quantities ensure thickness and the quality of coating.     

Enzyme‐assisted aqueous extraction of oil and protein from canola (Brassica napus L.) seeds

The emphasis of this study was to investigate the effect of enzymes on aqueous extraction of canola (Brassica napus L.) seed oil and protein. Four enzymes, Protex 7L, Multifect Pectinase FE, Multifect CX 13L, and Natuzyme, were tested for their effectiveness in releasing oil and protein during aqueous extraction. The enzyme‐extracted oil content of canola seeds (22.2–26.0%) was found to be significantly (p <0.05) higher than that of the control (without enzyme) (16.48%). An appreciable amount of protein (3.5–5.9%) originally present in the seed was extracted into the aqueous and creamy phases during aqueous extraction of oil. The physicochemical properties of oils extracted from canola seed by conventional solvent extraction, and aqueous extraction, with or without enzyme addition were compared. Significant (p <0.05) differences were observed in free fatty acid content, specific extinctions at 232 and 270 nm, peroxide value, color (1‐inch cell) and concentration of tocopherols (α, γ, and δ). However, no significant variation (p <0.05) was observed in iodine value, refractive index (40 °C), density (24 °C), saponification value, unsaponifiable matter and fatty acid composition. A better oil quality was obtained with aqueous extraction (with and without enzyme) than with solvent extraction. While the enzymes enhanced the oil extraction, the oil yield was still significantly (p <0.05) lower than that obtained by solvent (hexane) extraction.     

Evaluation of microstructure and mechanical properties of squeeze overcast Al7075-Cu composite joints

Al7075-Cu composite joints were prepared by the squeeze overcast process. The effects of melt temperature, die temperature, and squeeze pressure on hardness and ultimate tensile strength(UTS) of squeeze overcast Al7075-Cu composite joints were studied. The experimental results depict that squeeze pressure is the most significant process parameter affecting the hardness and UTS. The optimal values of UTS(48 MPa)and hardness(76 HRB) are achieved at a melt temperature of 800 ℃, a die temperature of...     

Effect of microstructure change on resistance of spherical LiCoO2 to electrode degradation for proton intercalation

Lithium cobalt oxide (LCO) with layered crystal structure suffers the structural proton intercalation in aqueous electrolytes of low pH values, little information is available about the effect of microstructure change on the cycling stability of LCO in response to the proton intercalation. In this work, electrochemical properties of three kinds of LCO spheres with different microstructures are studied in neutral aqueous 0.5 M Li₂SO₄ solution. The investigated materials were obtained by calcining the spherical LCO precursors at various temperatures, which were synthesized via a modified solid phase method for lithiation of spherical Co₃O₄. Structure and morphology of materials were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The spherical LCO prepared at lower temperature shows more superior electrochemical stability. Herein, the resistance of spherical LCO with a particular microstructure to the electrode degradation for the proton intercalation can be measured by the frequency of occurrences of greater-than-100% coulombic efficiencies during cycling. Meanwhile, the capability of retaining the capacity contribution from the order-to-disorder transformation of lithium ions on the hexagonal lattice of host site after the first-order phase transition was proposed to compare and investigate the cyclability of the three kinds of spherical LCO with different microstructures.     

Energy efficient virtual MIMO communication for wireless sensor networks

Virtual multiple input multiple output (MIMO) techniques are used for energy efficient communication in wireless sensor networks. In this paper, we propose energy efficient routing based on virtual MIMO. We investigate virtual MIMO for both fixed and variable rates. We use a cluster based virtual MIMO cognitive model with the aim of changing operational parameters (constellation size) to provide energy efficient communication. We determine the routing path based on the virtual MIMO communication cost to delay the first node death. For larger distances, the simulation results show that virtual MIMO (2×2) based routing is more energy efficient than SISO (single input single output) and other MIMO variations.     

Eu–Co substituted Sr-hexaferrites for recording media and microwave devices

Journal of Materials Science: Materials in Electronics - Among ferrites materials, M-type hexaferrites are very important due to their excellent technological applications. In the present...     

Conductive and antibacterial cellulose nanofibers decorated with copper nanoparticles for potential application in wearable devices

One of the contributions of nanotechnology to our daily life is the preparation of a large variety of polymer-based nanofibers, which could be the basis of future wearable devices. Wearable electronics are a great part of smart textiles research. Herein, we have reported an easy method to fabricate electrically conductive cellulose nanofibers (CNFs). To fabricate CNFs, we first prepared cellulose acetate (CA) nanofibers by using the electrospinning technique and later, the deacetylation process was done to obtain the CNFs. The electroless deposition (ELD) technique was then used to create the conductive nanofibers. Copper (Cu) was used to coat the CNFs because of their high conductivity and low cost. The ELD process parameters including time, temperature, volume, and pH were optimized to obtain a nanofiber with higher conductivity. The optimized condition was temperature: 40 °C, time: 10 min, volume: 600 ml, and pH: 13 to obtain a nanofiber web with 983.5 S/cm conductivity. Cu-coated CNFs were characterized by scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, water contact angle, antibacterial activity, tensile, and electrical conductivity. The bending cycle test was performed to quantitatively demonstrate the durability and flexibility of the Cu-coated nanofibers. Cu-coated CNFs exhibited great performance to be used as a conductive layer with antibacterial activity.