Alcalase-generated proteolysates of stone fish (Actinopyga lecanora) flesh as a new source of antioxidant peptides

In the present study, the alcalase-generated proteolysates obtained after 8 h of proteolysis of stone fish flesh showed the most potent antioxidant activity in terms of DPPH^? radical scavenging activity (77.43%, IC₅₀ of 0.5 mg/mL), ABTS^? radical scavenging activity (92.73%, IC₅₀ of 0.33 mg/mL) and FRAP value (39.2 mmol/100 mL FeSO₄). These proteolysates profiled and characterized as antioxidative peptides. The proteolysates were initially subjected to ultrafiltration using MWCO Spin-X UF. Potent fractions were further characterized based on hydrophobicity using reversed-phase high-performance liquid chromatography (RP-HPLC) and isoelectric point using an OFFGEL isoelectric focusing fractionator. Results indicated that most of the antioxidative peptides found in fractions with a molecular weight (MW) of less than 2 kDa, hydrophilic (hydrophilicity >80%) and basic (pI = 9.7). The final purified fraction with the highest antioxidant activity was selected for peptide identification and sequencing using Q-TOF mass spectrometry. A total of four peptides were identified, from which Peptide 1 (GVSGLHID) showed the highest antioxidant activity and this has potential as a novel bioingredient of nutraceuticals and functional foods to promote human health.     

Effect of Binary and Ternary Combination of Metal Salt Mordants on Dyeing and Fastness Properties of Natural Protein Fibre with Juglans regia L. Dye

The present article focuses on the effect of different combinations of metal mordants on color characteristics and fastness properties of natural dye extracted from Juglan regia L bark powder. The influence of different types of mordant combinations such as alum + ferrous sulphate, alum + stannous chloride, ferrous sulphate + stannous chloride, and alum + ferrous sulphate + stannous chloride on color parameters has been investigated in terms of CIELab (L*, a*, b*, c*, and h°) and K/S values. The fastness properties with respect to light, washing, and crocking of developed shades were determined according to ISO and AATCC test methods. Based on the experimental results, it has been found that 96 shades with novel and fashionable hues were produced by the use of these metal salt combinations. It was also found that all mordanted samples had satisfactory light and wash fastness ratings. Dry rub fastness was found relatively better than wet rub fastness.     

Hydroxyapatite and Fluoridated Hydroxyapatite Coatings and Their Effects on Commercially Pure Magnesium Corrosion Response

Dicalcium-phosphate dehydrate, converted to hydroxyapatite by post-treatment in sodium hydroxide, and fluoridated hydroxyapatite were electrodeposited on commercially pure magnesium substrates that were pretreated with sodium hydroxide. The coatings’ crystalline structure, thickness, scratch hardness, morphology and chemical composition were characterised by GIXRD, microscratch testing platform, SEM and EDS. The results showed that the apatite coatings had highly crystalline structure, acceptable scratch hardness, flake-like morphology and acceptable chemical composition. Corrosion behaviour of the uncoated and coated substrates was investigated by potentiodynamic polarization and immersion tests in simulated body fluid. The coated substrates, especially fluoridated hydroxyapatite coated substrates, showed significantly lower corrosion rates compared to uncoated substrates. The polarisation curves showed that the coatings hindered anodic reactions; the corrosion potentials were shifted toward less-negative. In general, this study concluded that the corrosion rate of commercially pure magnesium could be significantly decreased to be a candidate for future cost-effective biodegradable orthopaedic implants.     

Development of Cutting Tool Through Superplastic Boronizing of Duplex Stainless Steel

In this study, a cutting tool is developed from duplex stainless steel (DSS) using the superplastic boronizing technique. The feasibility of the development process is studied, and the cutting performances of the cutting tool are evaluated and compared with commercially available carbide and high-speed steel (HSS) tools. The superplastically boronized (SPB) cutting tool yielded a dense boronized layer of 50.5 µm with a surface hardness of 3956 HV. A coefficient of friction value of 0.62 is obtained, which is lower than 1.02 and 0.8 of the carbide and HSS tools. When tested on an aluminum 6061 surface under dry condition, the SPB cutting tool is also able to produce turning finishing below 0.4 µm, beyond the travel distance of 3000 m, which is comparable to the carbide tool, but produces much better results than HSS tool. Through superplastic boronizing of DSS, it is possible to produce a high-quality metal-based cutting tool that is comparable to the conventional carbide tool.     

ZnO microstructures and nanostructures prepared by sol-gel hydrothermal technique

Zinc oxide (ZnO) is an emerging material in large area electronic applications such as thin-film solar cells and transistors. We report on the fabrication and characterization of ZnO microstructures and nanostructures. The ZnO microstructures and nanostructures have been synthesized using sol-gel immerse technique on oxidized silicon substrates. Different precursor's concentrations ranging from 0.0001 M to 0.01 M (M=molarity) using zinc nitrate hexahydrate [Zn(NO3)2. 6H2O] and hexamethylenetetramine [C6H12N4] were employed in the synthesis of the ZnO structures. The surface morphologies were examined using scanning electron microscope (SEM) and atomic force microscope (AFM). In order to investigate the structural properties, the ZnO microstructures and nanostructures were measured using X-ray diffractometer (XRD). The optical properties of the ZnO structures were measured using photoluminescence (PL) and ultraviolet-visible (UV-Vis) spectroscopies.     

Degradation of compressive properties of pultruded kenaf fiber reinforced composites after immersion in various solutions

In this paper, water absorption behavior of pultruded kenaf fiber reinforced unsaturated polyester composites was investigated. Residual compressive properties of the composites after immersion were also reported. Composites were prepared using pultrusion method with minimum kenaf fiber content of 70% w/w. Water absorption tests were performed at room temperature under three different solutions, i.e. distilled water, sea water and acidic solution. The diffusion coefficient of water absorption and maximum moisture content were calculated by measuring the water uptake of specimen at regular time interval. Diffusion coefficient and the highest moisture content values were recorded for composite immersed in distilled water followed by acidic solution and sea water. The water absorption of kenaf fiber reinforced unsaturated polyester composites was found to follow a Fickian’s behavior where it reach equilibrium. The compressive properties were found to decrease with the increase in the percentage of water uptake. The decay in compression properties is attributed to the plasticization of the fiber–matrix interface and swelling of the kenaf fiber.