MWCNTs-Reinforced Epoxidized Linseed Oil Plasticized Polylactic Acid Nanocomposite and Its Electroactive Shape Memory Behaviour

A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %), with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC), tensile test, and thermo gravimetric analysis (TGA). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME) in the resulting nanocomposite was investigated by a fold-deploy “U”-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices.     

Fabrication of Mn–Co Spinel Coatings on Crofer 22 APU Stainless Steel by Electrophoretic Deposition for Interconnect Applications in Solid Oxide Fuel Cells

This study investigates the microstructure, oxidation kinetics, and electrical behavior of Mn–Co spinel coating for interconnect applications in solid oxide fuel cells. A relatively dense, uniform, and well‐adherent Mn–Co (Mn_1.5Co_1.5O₄) spinel coating with good oxidation resistance and stable conductivity was successfully prepared on the surface of Crofer 22 APU stainless steel using electrophoretic deposition followed by sintering at 1150°C. During further thermal treatment at 800°C, the chromium oxide (Cr₂O₃) sublayer formed at the substrate/coating interface during sintering showed a very slow growth, and no chromium penetration was detected in the Mn–Co coating. The oxidation kinetics of the Mn–Co‐coated substrate obeyed the parabolic law with the a parabolic rate constant k_p of 5.20 × 10^?15 g²/cm⁴/s, which was 1–2 orders of magnitude lower than that of the uncoated Crofer 22 APU stainless steel substrate. For oxidation (at 800°C) times ≥50 h, the area‐specific resistance of the Mn–Co‐coated Crofer 22 APU substrate became ~17 mΩ·cm² and was almost constant after further oxidation.     

Influence of monosodium glutamate additive on the morphology and permeability characteristics of polyamide dialysis membranes

Membranes were prepared with dope solutions of various concentrations of polyamide and monosodium glutamate (MSG) additive for dialysis applications. The results show that the membranes with higher MSG concentrations had higher water uptakes and porosities. The membranes were characterized with scanning electron microscopy (SEM) and atomic force microscopy techniques and evaluated in terms of the permeability of solutes, such as urea and creatinine. The cross‐sectional structure of the membranes prepared without MSG additive or with a low MSG concentration were dense, and their surfaces consisted of large‐sized nodule aggregates. The permeation of solutes was less through these membranes. When the amount of additive in the membrane solution was sufficient, macrovoids were seen in the SEM images, and the sizes of nodules were small, which caused an increase in the diffusive permeability of solutes. The surfaces of the membranes with higher MSG concentrations were found to be smooth; this could be useful for the dialysis process. The contact angles of these membranes were also lower; this indicated that this additive improved the hydrophilicity of the membranes. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mobile radio propagation path loss studies at VHF/UHF bands inSouthern India

Field strength measurements at 200, 400 and 450 MHz (VHF/UHF band) were conducted with the field strength meter placed on board a vehicle in Southern India. Observed field strength values were converted into path losses and are compared with different path loss prediction methods like Hata (1980), Egli (1957), Blomquist-Ladell (1974), COST 231 Walfisch-Ikegami (Doble 1996), Walfisch-Bertoni (1988) and ITU-R. These path loss studies are carried out in urban, suburban and open areas in this region. The results showed that Hata's method gave better agreement with observed values in urban, suburban and open regions; the COST 231 Walfisch-Ikegami model is also in good agreement with the observed values in urban and suburban regions, the Egli and Blomquist-Ladell methods showed moderate agreement in open regions only. The agreement of the Walfisch-Bertoni and ITU-R methods with observed values is not good     

Hydrokinetic energy conversion systems and assessment of horizontal and vertical axis turbines for river and tidal applications: A technology status review

The energy in flowing river streams, tidal currents or other artificial water channels is being considered as viable source of renewable power. Hydrokinetic conversion systems, albeit mostly at its early stage of development, may appear suitable in harnessing energy from such renewable resources. A number of resource quantization and demonstrations have been conducted throughout the world and it is believed that both in-land water resources and offshore ocean energy sector will benefit from this technology. In this paper, starting with a set of basic definitions pertaining to this technology, a review of the existing and upcoming conversion schemes, and their fields of applications are outlined. Based on a comprehensive survey of various hydrokinetic systems reported to date, general trends in system design, duct augmentation, and placement methods are deduced. A detailed assessment of various turbine systems (horizontal and vertical axis), along with their classification and qualitative comparison, is presented. In addition, the progression of technological advancements tracing several decades of R&D efforts are highlighted.     

Determination of selenium content in selected Pakistani foods

Owing to increased concern in a number of diseases associated with low-selenium (Se) foods, the estimation of total Se content (TSC) is the focus of research these days. TSC was determined in fruits, vegetables, meat, milk, poultry, fish and cereals. Hydride generation atomic absorption spectrometric method was employed using the wet digestion method. Different certified reference materials were used for the validation of the method. The lowest Se content was found in plant-based foods, whereas the highest was in fish and appreciable in other animal-based foods. The data was compared with TSC data from other countries. TSC in Pakistani foods was comparable with other countries, with few exceptions. This report may serve as a database for TSC in Pakistani foods.     

Effect of Minimal Processing Conditions on Respiration Rate of Carrots

ABSTRACT: Measurement, analysis, and modeling of respiration rate (RR) of fresh produce are fundamental for the engineering design of MAP. This study investigates the effect of type of cutting (sliced in circular shape, batons in rectangular shape, and shredded into thin strips) on the respiration rate of carrots at different temperatures (4, 8, 12, 16, and 20 °C) with ambient atmosphere. The higher respiration rates were found for shredded carrots and the lowest for whole carrots at all the temperatures tested. The RR increased from 9 ± 1 to 26 ± 3, 10 ± 1 to 53 ± 2, 11 ± 1 to 55 ± 2, and 18 ± 1 to 75 ± 3 mL of O₂ per kilogram hour for whole, sliced, baton, and shredded carrots, respectively, as the temperature increased from 4 to 20 °C. On an average, RO₂ and RCO₂ were increased by 85% and 64%, 100% and 72%, and 151% and 124% for sliced, baton, and shredded carrots, respectively, compared to the RR values of whole carrots. The temperature dependence of RR followed an Arrhenius‐type relationship for all types of carrots, with activation energies in the range of 35 ± 3 to 62 ± 2 kJ/mol. Type of cut was the major factor for both RO₂ and RCO₂, with shredded carrots having the highest rates and whole carrots the lowest. RR of whole carrots did not vary during storage, whereas it increased for cut carrots and especially for shredded carrots. The respiratory quotient (RQ) increased with temperature and did not vary during storage in all types of carrots, except the RQ of whole carrots decreased significantly over time.     

Nutritional quality of important food legumes

The proximate composition, mineral constituents and amino acid profile of four important legumes (chickpea, lentil, cowpea and green pea) were studied in order to evaluate their nutritional performance. Significant (P < 0.05) variations existed among the legumes with respect to their proximate composition, mineral constituent and amino acid profile. Lentil was found to be a good source of protein, while cowpea was good in ash among the grain legumes tested. All four types of legumes were also better suppliers of mineral matter, particularly potassium, phosphorus, calcium, copper, iron, and zinc. However, the concentrations of various mineral constituents was not in good nutritional balance. It was concluded that the four legumes tested were rich in lysine, leucine and arginine and can fulfil the essential amino acid requirement of human diet except for S-containing amino acids and tryptophan. In order to make good, the deficiency of certain essential amino acids in legume protein, they must be supplemented with other vegetables, meat and dairy products (e.g., Whey, yogurt).     

Thermosetting ROMP materials with thermally degradable linkages

Mono- and di-functional norbornene dicarboximide monomers containing acetal ester groups were synthesised. The ROMP of the di-functional monomer using Grubbs ruthenium first generation initiator at ambient temperature produced crosslinked material. Materials with various crosslink densities were prepared by the ROMP, under the same condition, of mixtures of the mono- and di-functional monomers. The FT-IR spectra clearly showed the presence of an acetal C-O band at 1135 cm⁻¹. The TGA study of the crosslinked materials showed that they are stable to 150 °C and that they exhibit rapid breakdown at about 200 °C, as the result of the thermal decomposition of the acetal ester linkage. FT-IR analysis of the retrieved materials following TGA-MS showed that the intensity of acetal C-O band at 1135 cm⁻¹ was greatly reduced.