Microwave absorption properties of (1 − x)La0.85Ag0.15MnO3/x graphene (x = 0, 3, and 5 wt.%) composites

Composite of (1 − x)La_0.85Ag_0.15MnO₃/x graphene (x = 0, 3, and 5 wt.%) and epoxy resin with a ratio of 4:1 were prepared to investigate the influence of the addition of graphene in (1 − x)La_0.85Ag_0.15MnO₃/x graphene on real and imaginary parts of permittivity, permeability, as well as microwave reflection loss (RL), using a vector network analyzer in the 8–18 GHz of the frequency range. It is found that the value of RL is smaller at x = 3 wt.% (−20.74 dB at 14.85 GHz) and 5 wt.% (−14.81 at 16.50 GHz) compared to at x = 0 wt.% (−8.89 dB at 15.90 GHz). The result indicates that microwave absorption properties significantly improved as a result of the addition of graphene. It is suggested that the addition of graphene enhanced the dielectric loss–related mechanism such as interfacial polarization and conduction loss resulting in an improvement of microwave absorption performance for both x = 3 wt.% and x = 5 wt.% samples. It also shows that the observed enhanced microwave absorption properties may also be influenced by the resistivity of the sample as x = 3 wt.% sample exhibits enhanced microwave absorption properties and the lowest resistivity among the studied samples.     

Syngas Production via Bi-Reforming of Methane Over Fibrous KCC-1 Stabilized Ni Catalyst

Topics in Catalysis - Bi-reforming of methane (BRM) technology has the potential to serve as an alternative energy source while also mitigating greenhouse gas emissions. However, the main hurdle in...     

Symmetric and asymmetric impacts of the palm oil industry on carbon dioxide emissions in Malaysia based on linear and nonlinear autoregressive distributed lag models

Clean Technologies and Environmental Policy - Palm oil is a major global commodity that is vital for the well-being of many communities. Despite its significant contribution to the attainment of...     

Production of N-methyldiethanolamine di-ester via heterogeneous transesterification of palm methyl ester over modified calcium oxide catalyst by metal oxides

The production cycle of the heterogeneous catalyzed-transesterification of methyl ester and alkanolamine for the production of esterquats precursor can be considered as a cleaner and sustainable process. This process is an important alternative route as opposed to the conventional homogeneous catalysis as it can eliminates the formation of wastewater, consumes less toxic chemical and reduce the production cost through catalyst reuse. Calcium oxide (CaO)-based catalysts which include pure CaO and modified CaO by other metal oxides were employed in this study for the production of alkanolamine ester, a precursor of esterquats. The basicity and textural properties of these catalysts were characterized using TPD-CO₂ and N₂ physisorption, respectively. Transesterification activity of CaO-based catalysts successfully showed a high di-ester yield of more than 85% at 160°C, 80 mbar, 4 wt% of catalyst dosage, 6 h reaction time, methyl palmitate to N-methyldiethanolamine mole ratio of 2:1 and agitation speed of 150 rpm. ZnO/CaO catalyst rendered the best durability characteristic as it exhibited constant activities for three subsequent runs with 85% di-ester yield. ZnO/CaO showed high catalytic activity similar to pure CaO catalyst with low leaching of Ca active phase and better reusability than that of pure CaO catalyst, that shows loss of its activity after the first cycle.     

Comparison of high pressure and thermal pasteurization on the quality parameters of strawberry products: a review

Food Science and Biotechnology - Strawberry (Fragaria ananassa) is rich in bioactive compounds with high antioxidant activity. High pressure processing (HPP) is an efficient alternative to preserve...     

Effects of Positive Carbon Quantum Dots on Gram-Negative Bacteria as an Antimicrobial Agent

Journal of Inorganic and Organometallic Polymers and Materials - Non-radiative decay is the main limitation to applications of the excellent optical properties of carbon quantum dots. Moreover, the...     

Recent progress in food processing applications of air impingement technology: A review

Air impingement method has been widely used in a variety of industrial applications, such as textile and paper drying, turbine cooling, and glass quenching, because it is an efficient technology with high heat and mass transfer rates. This technology has received increasing interest in the field of food processing over the last two decades, such as drying, baking, blanching, freezing, and thawing. In a food processing equipment using air impingement, jets of high-velocity air (with speeds of 10–50 m/s) are directed at a food product. The performance of the system is influenced by several critical elements, including jet velocity, nozzle array diameter and layout, jet distance, and boundary layer characteristics. The use of computational fluid dynamics, an emerging tool, has been shown to be valuable in the analysis of fluid flow and heat and mass transfer in jet impingement systems. The physical properties of impinging jets, such as turbulent mixing in the free jet zone, stagnation, boundary layer formation, recirculation, and their interactions with food products in terms of heat and mass transfer, have been discussed in this article. The benefits and disadvantages of air jet impingement technology in different food processing applications together with potential trends for improving impingement technology performance were identified and discussed. This review not only contributes to a better understanding of the research status of impingement technology on food processing but also triggers new research opportunities in this field in order to provide more healthy and nutritious food in a more sustainable way to the world's growing population.