Antioxidant activity of various extracts from an edible mushroom Pleurotus eous

Pleurotus eous is a pink edible oyster mushroom cultivated in Coimbatore. The aim of present study was to evaluate antioxidant potential of ethyl acetate, methanol, and hot water extracts from P. eous using various in vitro ROS/RNS generated chemical and biological models. Results demonstrated that the graded-dose (2–50 mg/mL) of various extracts markedly scavenged the DPPH, ABTS, and hydroxyl radicals, and showed metal chelating ability, reducing capacity in Fe³⁺/ferricyanide complex, and ferric reducing antioxidant power assays. In biological models, different extracts were found to inhibit lipid peroxidation in brain and liver homogenate. Total antioxidant activity was high in methanolic extract. Hot water extract showed higher amount of total phenol and methanolic extract showed higher amount of flavonoid as compared to other extracts. Based on EC₅₀ values it can be concluded that the various extracts from P. eous were good in antioxidant properties with methanol and ethyl acetate extracts being more effective. The results of this study showed that various extracts could serve as natural antioxidants owing to their significant antioxidant activity.     

Additive manufactured bipolar plate for high-efficiency hydrogen production in proton exchange membrane electrolyzer cells

Additive manufacturing (AM) technology is capable of fast and low-cost prototyping from complex 3D digital models. To take advantage of this technology, a stainless steel (SS) plate with parallel flow field served as a combination of a cathode bipolar plate and a current distributor; it was fabricated using selective laser melting (SLM) techniques and investigated in a proton exchange membrane electrolyzer cell (PEMEC) in-situ for the first time. The experimental results show that the PEMEC with an AM SS cathode bipolar plate can achieve an excellent performance for hydrogen production for a voltage of 1.779 V and a current density of 2.0 A/cm². The AM SS cathode bipolar plate was also characterized by SEM and EDS, and the results show a uniform elemental distribution across the plate with very limited oxidization. This research demonstrates that AM method could be a route to aid cost-effective and rapid development of PEMECs.     

Advance Electronic Load Controller for Micro Hydro Power Plant

Most of the MHP （micro hydro power） plants use ELC （electronic load controller） for speed control. Various types of ELC have been developed so far. A dummy ballast load is connected across each phase of generator terminals and ELC controls the power consumed by the ballast load to result in constant speed operation. The ELC developed so far uses thyristor switches in each phase to control ballast load power. The ELC senses the system frequency and comparing it with reference frequency, it generates a common value of firing angle for all three thyristor pairs of each phase. The performance of such ELC is not perfect for unbalanced consumers load connected in each phase, which overloads the generator. This paper presents an advanced type of ELC which senses frequency as well as consumer＇s load current of each phase and fires the thyristor pairs with different value of firing angles for different phases. This solves the problem of overloading of the generator with unbalanced consumer＇s load. Simutink model is developed to perform transient analysis of the proposed scheme and the prototype of hardware is also fabricated. The simulation results and experimental results are presented.     

Numerical and Experimental Investigations of Heat Removal Performance of Sodium-to-Air Heat Exchanger Used in Fast Reactors

Sodium-to-air heat exchangers (AHX) are used in fast breeder reactors for removal of decay heat generated in the core after a reactor shutdown. The AHX is an important component of the safety-grade decay heat removal system in a fast reactor. Decay heat removal critically depends on the performance of the AHX, which is essentially a cross-flow heat exchanger with liquid sodium flowing on the tube side and air flowing across finned tubes in the cross-flow mode. In this paper, a three-dimensional numerical study is carried out to investigate the flow and heat transfer characteristics when air flows over a representative bank of finned tubes in an AHX. The computational model has been validated against published experimental benchmarks. Based on parametric studies, appropriate correlations for the Nusselt number and fin effectiveness are derived. A computationally efficient porous body model is then developed and an integrated thermal hydraulics study of AHX is carried out using the derived heat transfer correlation. The numerical predictions of the porous body model are compared with the results of an experimental AHX tested at the Indira Gandhi Centre for Atomic Research; Kalpakkam, India. A good agreement between the results is seen.     

A correlation for heat transfer during laminar natural convection in an enclosure containing uniform mixture of air and hydrogen

In this paper, a correlation for heat transfer due to laminar natural convection in a rectangular enclosure containing a uniform mixture of hydrogen and air with vertical walls at different temperatures is proposed. This correlation is in terms of Nusselt and Rayleigh numbers evaluated by taking properties of air alone. Mixture properties, viz., density, viscosity, specific heat capacity and thermal conductivity are not needed in this correlation. A modification factor which is based on the mole fraction of hydrogen in the mixture accounts for the differences in heat exchange due to differences in the properties of mixture and pure air. Thus, this correlation is easier to use for a dilute mixture of hydrogen and air as compared to the conventional correlations that are based on mixture properties which may be cumbersome to evaluate. Further, the results highlight that heat transfer correlations for a mixture of gases can be expressed in terms non-dimensional numbers for dominant gas and a correction factor for the gas mixing with it. An in-house code HDS (Hydrogen Distribution Simulator), which has well validated modules for calculation of mixture properties, has been used to carry out numerical study and establish this heat transfer correlation.     

Impact of cosolvent (glucose) on the stabilization of ovalbumin

Proteins are stabilized by glucose against denaturation due to extremes of pH. This was studied by means of density, ultrasonic velocity, viscosity and surface tension measurements in the ovalbumin (5 mg/ml) dissolved in phosphate buffer (pH 2, 5, 7, 9 and 12). Few thermo-acoustical parameters such as adiabatic compressibility, intermolecular free length, acoustic impedance, the partial apparent specific volume and the partial apparent specific adiabatic compressibility were calculated for the said systems. Obtained results suggest that the stabilization of ovalbumin occurs in the presence of glucose through strengthening of hydrophobic interactions supported by other non-covalent interactions and the steric exclusion effect of the cosolvent molecules.     

Characterizing microstructural changes in ferritic steels by positron annihilation spectroscopy: Studies on modified 9Cr–1Mo steel

Applicability of positron annihilation spectroscopy in probing the microstructural changes in ferritic steels has been investigated with thermal treatment studies on modified 9Cr–1Mo steel, during 300–1273 K. Positron lifetime results are compared with those of ultrasonic velocity and hardness techniques with two initial microstructural conditions i.e., normalized and tempered condition as well as only normalized condition. In first case, positron lifetime is found to be sensitive to small changes in metal carbide precipitation which could not be probed by other two techniques. In later case, positron lifetime is found to be sensitive to defect annealing until 673 K and in distinguishing the growth and coarsening of metal carbide precipitation stages during 773–1073 K. The present study suggests that by combining positron lifetime, ultrasonic velocity and hardness measurements, it is possible to distinguish distinct microstructures occurring at different stages.     

Influence of protein content and storage temperature on the particle morphology and flowability characteristics of milk protein concentrate powders

Milk protein concentrate (MPC) powders are widely used as ingredients for food product formulations due to their nutritional profile and sensory attributes. Processing parameters, storage conditions, and composition influences the flow properties of MPC powders. This study investigated the bulk and shear flow properties of 70.3, 81.5, and 88.1% (wt/wt, protein content) MPC after storage for 12 wk at 25 and 40°C. Additionally, the morphological and functional changes of the MPC powders were investigated and correlated with flowability. After 12 wk of storage at 25°C, the basic flow energy values significantly increased from 510 to 930 mJ as the protein content increased from 70 to 90% (wt/wt). Flow rate index was significantly higher for samples with high protein content. Dynamic flow tests indicated that MPC powders with high protein content displayed higher permeability. Shear tests confirmed that the samples stored at 25°C were more flowable than samples stored at 40°C. Likewise, the higher-protein content samples showed poor shear flow behavior. The results indicated that MPC powders stored at 25°C had less cohesiveness and better flow characteristics than MPC powders stored at 40°C. Overall, the MPC powders had markedly different flow properties due to their difference in composition and morphology. This study delivers insights on the particle morphology and flow behavior of MPC powders.