New heat treatment technique (tempering-austempered in single treatment) for matrix transformation and mechanical properties of ductile iron / Bulan Abdullah … [et al.]

A new heat treatment process which synthesized using the concepts from Austempered Ductile Cast Iron (ADI), Tempering and Quenching technology. The metallurgy of materials matrix transformation on each sequential cycle with different parameter such as time and temperature will be determine through the mechanical properties of ductile iron. Samples for the testing specimen will produce using the C02 casting. The compositions of samples will be determined by using the spectrometer machine. The heat treatment process consists of Quenching, Austempering and new developed heat treatment process with different parameter such as time and temperature. The new developed heat treatment process will be synthesized using the concepts from Austempered Ductile Cast Iron (ADI) and Quenching technology. The micro structure of specimens will be observed on each sequential cycle of heat treatment process. The chemical information of matrix surface will gain through the energy Dispersive X-Ray spectroscopy (EDX). The hardness, impact (ASTM E23), tensile (TS 138 EN10002-1) and density test were carried out before and after heat treatment process. The fracture surface of the tensile and impact samples will examine under Scanning Electron Microscope (SEM). A treatment process is expected possessed the better mechanical properties compared to conventional heat treatment can be used for the specific application that suite th

Marine-inspired enzymatic mineralization of dairy-derived whey protein isolate (WPI) hydrogels for bone tissue regeneration

Whey protein isolate (WPI) is a by-product from the production of cheese and Greek yoghurt comprising β-lactoglobulin (β-lg) (75%). Hydrogels can be produced from WPI solutions through heating; hydrogels can be sterilized by autoclaving. WPI hydrogels have shown cytocompatibility and ability to enhance proliferation and osteogenic differentiation of bone-forming cells. Hence, they have promise in the area of bone tissue regeneration. In contrast to commonly used ceramic minerals for bone regeneration, a major advantage of hydrogels is the ease of their modification by incorporating biologically active substances such as enzymes. Calcium carbonate (CaCO3) is the main inorganic component of the exoskeletons of marine invertebrates. Two polymorphs of CaCO3, calcite and aragonite, have shown the ability to promote bone regeneration. Other authors have reported that the addition of magnesium to inorganic phases has a beneficial effect on bone-forming cell growth. In this study, we employed a biomimetic, marine-inspired approach to mineralize WPI hydrogels with an inorganic phase consisting of CaCO3 (mainly calcite) and CaCO3 enriched with magnesium using the calcifying enzyme urease. The novelty of this study lies in both the enzymatic mineralization of WPI hydrogels and enrichment of the mineral with magnesium. Calcium was incorporated into the mineral formed to a greater extent than magnesium. Increasing the concentration of magnesium in the mineralization medium led to a reduction in the amount and crystallinity of the mineral formed. Biological studies revealed that mineralized and unmineralized hydrogels were not cytotoxic and promoted cell viability to comparable extents (approximately 74% of standard tissue culture polystyrene). The presence of magnesium in the mineral formed had no adverse effect on cell viability. In short, WPI hydrogels, both unmineralized and mineralized with CaCO3 and magnesium-enriched CaCO3, show potential as biomaterials for bone regeneration

Characterization of microstructure, weld heat input, and mechanical properties of Mg−Al−Zn alloy GTA weldments

The present study investigated the influence of welding speed on the microstructure, hardness, and tensile properties of the AZ31 Mg alloy gas tungsten arc (GTA) welds that were prepared using alternating current (AC). A microstructural examination of the weld metal and base metal was performed using stereo, optical, and scanning electron microscopy (HR-SEM and EDS) techniques. The microstructure of all fusion zones consists of two parts: a columnar zone, adjacent to the fusion boundary, and equiaxed grains, in the centre of the weld fusion zone. It is shown that the average width of the equiaxed zone present at the centre of the fusion zone increases with increasing welding speed. Metallographic examination shows that the highest welding speed (5 mm/s) results in the smallest average grain size. The welds prepared with high welding speed exhibit an increase in strength, hardness, and ductility compared with other welding speeds, which is attributed to low heat input

Bioactive Nano Hydroxyapatites for Orbital Floor Repair and Regeneration

Bioactive nano-hydroxyapatites have been synthesised for orbital floor repair and regeneration. Hydroxyapatite (HA) is widely used for bone repair and regeneration. It is composed of multiple anionic and cationic species, such as carbonate, fluoride, phosphate, sodium, magnesium, silicon and citrate. However, the development of bioactive materials that can repair and regenerate bone is crucial for orbital floor fracture repair. Different ionic-substituted hydroxyapatites that included carbonate, fluoride and citrate were prepared by using a low-temperature hydrothermal flow process and their chemical and physical properties evaluated. Biological properties were evaluated by analysing cell viability of these synthesised materials by Alamar Blue cell metabolic activity assay with two different cell lines (MG63 and HTERT-BMSC’s). Results confirmed that ionic substitution with fluoride and citrate improved biocompatibility and cell viability of synthesised hydroxyapatites

Single-cell Raman microscopy of microengineered cell scaffolds

Studying cells in a three‐dimensional (3D) environment has great potential in understanding cell behaviours such as morphology, proliferation, differentiation, and migration. Microengineered 3D cell scaffolds with precise defined geometries have offered a new approach to study cell behaviour and its interactions with scaffolds. The use of Raman spectroscopy to characterise biomolecules is a rapidly expanding area and has been implemented in numerous fields including pharmacology, microbiology, toxicology, and single‐cell studies. However, one area where it remains unexploited despite the vast potential of the technique is in the investigation of 3D cell scaffolds. A combination of Raman microscopy and chemometric approaches have employed to investigate the structure and biochemistry of nanofabricated scaffolds and a cell–scaffold complex. The 3D Raman mapping combined with the use of nanofabricated 3D scaffolds offers a unique opportunity to assess the influence of scaffold architecture on cell body and cell nuclei morphology and biochemistry. For the first time, we have cultured a human epithelial colorectal adenocarcinoma cell line on OrmoComp scaffolds and determined the structure and biochemistry of nanofabricated scaffolds and a cell–scaffold complex with the use of Raman microscopy combined with appropriate data analysis protocols. The results demonstrate the potential of 3D Raman mapping for identifying biochemical and physical variation within single cells as they grow and adhere to 3D scaffolds

Bioactive Composite for Orbital Floor Repair and Regeneration

In the maxillofacial area, specifically the orbital floor, injuries can cause bone deformities in the head and face that are difficult to repair or regenerate. Treatment methodologies include use of polymers, metal, ceramics on their own and in combinations mainly for repair purposes, but little attention has been paid to identify suitable materials for orbital floor regeneration. Polyurethane (PU) and hydroxyapatite (HA) micro- or nano- sized with different percentages (25%, 40% & 60%) were used to fabricate bioactive tissue engineering (TE) scaffolds using solvent casting and particulate leaching methods. Mechanical and physical characterisation of TE scaffolds was investigated by tensile tests and SEM respectively. Chemical and structural properties of PU and PU/HA scaffolds were evaluated by infrared (IR) spectroscopy and Surface properties of the bioactive scaffold were analysed using attenuated total reflectance (ATR) sampling accessory coupled with IR. Cell viability, collagen formed, VEGF protein amount and vascularisation of bioactive TE scaffold were studied. IR characterisation confirmed the integration of HA in composite scaffolds, while ATR confirmed the significant amount of HA present at the top surface of the scaffold, which was a primary objective. The SEM images confirmed the pores’ interconnectivity. Increasing the content of HA up to 40% led to an improvement in mechanical properties, and the incorporation of nano-HA was more promising than that of micro-HA. Cell viability assays (using MG63) confirmed biocompatibility and CAM assays confirmed vascularization, demonstrating that HA enhances vascularization. These properties make the resulting biomaterials very useful for orbital floor repair and regeneration