Study of Corrosion Behavior and In Vitro Bioactivity of Single NbSi2 and Duplex NbSi2/Nb5Si3 Coatings on Nb Substrates for Biomedical Applications

Protection of Metals and Physical Chemistry of Surfaces - Single NbSi2 and duplex NbSi2/Nb5Si3 coatings were successfully applied on Nb substrates using halide activated pack cementation (HAPC)...     

Numerical and experimental study of conjugate heat transfer in a horizontal air cavity

The demand for general reduction of the energy consumption in civil engineering leads to more frequent use of insulating materials with air gaps or cavities. Heat transfer through a constructional part can be decreased by adding an air gap and low emissivity reflective foils to the structure. In the first part of this paper, the impacts of cavity thickness and inner surface emissivity on combined conduction, convection and radiation heat transfer was experimentally explored in the case of constructional part with a horizontal cavity subjected to constant downward heat flux. The heat flow meter Netzsch HFM 436 Lambda was used for steady-state measurements. Results suggest that the studied parameters seriously affect the combined heat transfer in the composed structure. In the second part the paper reports the numerical study of two-dimensional conjugate heat transfer in closed horizontal cavity having air as the intervening medium. Numerical models validated by related experimental results were performed to further investigate the effect of radiation heat transfer. It was found that in general, the total heat flux through the composed structure decreases with increasing air cavity thickness, which is significant especially when low emissivity inner surfaces are taking into account. The direction of heat flow (downward or upward heat flow) has a significant impact on the convection heat transfer. An important contribution from the present work is the analysis of the optimal thickness of the cavity at different boundary conditions. The optimal thickness of the enclosure with low emissivity surfaces is 16 mm when subjected to upward heat flux.     

Graphene‐based ternary composites for supercapacitors

The research on electrode materials for supercapacitor application continues to evolve as the request of high‐energy storage system has increased globally due to the demand for energy consumption. Over the past decades, various types of carbon‐based materials have been employed as electrode materials for high‐performance supercapacitor application. Among them, graphene is 1 of the most widely used carbon‐based materials due to its excellent properties including high surface area and excellent conductivity. To exploit more of its interesting properties, graphene is tailored to produce graphene oxide and reduced graphene oxide to improve the dispersibility in water and easy to be incorporated with other materials to form binary composites or even ternary composites. Nowadays, ternary composites have attracted enormous interest as 2 materials (binary composites) cannot satisfy the requirement of the high‐performance supercapacitor. Thus, many approaches have been employed to fabricate ternary composites by combining 3 different types of electroactive materials for high‐performance supercapacitor application. This review focuses on the supercapacitive performance of graphene‐based ternary composites with different types of active materials, ie, conducting polymers, metal oxide, and other carbon‐based materials.     

Effect of the presence of ethyl lauroyl arginate on the technological properties of edible fish gelatin films

Physical, chemical and antimicrobial properties of fish gelatin films with different concentrations of ethyl lauroyl arginate (LAE) were studied. Optical properties of film-forming solution did not vary with increased LAE content. However, pH and surface tension increased. The incorporation of LAE into the formulation increased moisture and solubility of the films. In addition, the presence of LAE affected mechanical properties, making films stronger and more flexible; it had no effect on water vapour permeability. Finally, films with LAE significantly increased antimicrobial properties against Listeria innocua, Shewanella putrefaciens and Pseudomonas fluorescens, but not against Aeromonas hydrophila. These antimicrobial films could be used as an alternative technology for extending shelf-life of fresh fish products.     

A Fluorometric Enzymatic Assay for Quantification of Steryl Glucosides in Biodiesel

Steryl glucosides (SG) are common contaminants in biodiesel that form precipitates, which form and cause problems due to fouling during transport and storage. Therefore, their quantification is necessary to assess the quality of this fuel. The methods currently available for SG analysis require expensive instrumentation, need a previous concentration step by solid‐phase extraction (SPE) or are of limited use for the quantitative assessment. We developed an enzymatic method for SG quantification in biodiesel samples based on the hydrolysis of the glucoside catalyzed by a broadly specific beta glucosidase and the subsequent determination of the glucose released by the reaction. The method is non‐expensive, sensitive and was adapted to 96‐well format fluorescence plate reader, making it useful for the parallel assay of multiple samples. The enzymatic assay presented here represent a valuable tool for both quality control and the development of improved biodiesel production and purification procedures.     

Sustainability of the four generations of biofuels – A review

Biofuel has emerged as an alternative source of energy to reduce the emissions of greenhouse gases in the atmosphere and combat global warming. Biofuels are classified into first, second, third and fourth generations. Each of the biofuel generations aims to meet the global energy demand while minimizing environmental impacts. Sustainability is defined as meeting the needs of the current generations without jeopardizing the needs of future generations. The aim of sustainability is to ensure continuous growth of the economy while protecting the environment and societal needs. Thus, this paper aims to evaluate the sustainability of these four generations of biofuels. The objectives are to compare the production of biofuel, the net greenhouse gases emissions, and energy efficiency. This study is important in providing information for the policymakers and researchers in the decision-making for the future development of green energy. Each of the biofuel generations shows different benefits and drawbacks. From this study, we conclude that the first generation biofuel has the highest biofuel production and energy efficiency, but is less effective in meeting the goal of reducing the greenhouse gases emission. The third generation biofuel shows the lowest net greenhouse gases emissions, allowing the reduction of greenhouse gases in the atmosphere. However, the energy required for the processing of the third generation biofuel is higher and, this makes it less environmentally friendly as fossil fuels are used to generate electricity. The third and fourth generation feedstocks are the potential sustainable source for the future production of biofuel. However, more studies need to be done to find an alternative low cost for biofuel production while increasing energy efficiency.     

Mechanisms of molecular and structural interactions between lentil and quinoa proteins in aqueous solutions induced by pH recycling

There has been a growing interest in plant proteins due to their beneficial health effects, low cost and variety of applications in food industries. The low solubility of lentil proteins (LPs) is one of the significant factors that limit their use in food applications. Quinoa proteins (QPs), which have high water solubility, were combined with LPs at pH 12 to generate LP-QP complexes to generate pH-based soluble protein compounds. The LP-QP complexes demonstrated a large surface charge with an increase solubilisation of the protein complexes by more than 85%, together with resistance to protein aggregation. The combination of LPs to QPs led to a significant increase (P < 0.05) in unique tertiary and secondary protein structures as determined by the protein–protein interaction (PPI) technique involving pH recycling. Interactions between LPs and QPs affected the surface morphology of the protein complexes formed. Electrostatic interactions, hydrophobic forces and hydrogen bonding were indicated to play key roles in the PPIs. The capacity of pH cycling to illustrate the above protein interactions shows that this is a robust approach for assessing the emulsion and foaming properties of food proteins.