In this work, the ability of polyvinylpyrrolidone (PVP)-stabilised gold nanoparticle (AuNP) coatings to inhibit blood protein adsorption was evaluated by studying time-resolved solid–liquid ...interactions of the coatings with the model blood protein bovine serum albumin (BSA). Inhibiting unspecific blood protein adsorption is of crucial importance for blood-contacting implant devices,
vascular grafts, stents, artificial joints, and others, as a preventive strategy for bacterial biofilm formation. A quartz crystal microbalance was used in this work to coat the AuNPs on piezoelectric sensors and to follow time-resolved solid–liquid interactions with the proteins. The AuNP coatings were evaluated for their wettability by contact angle measurements, their surface morphology by light- and atomic force microscopy, and their chemical composition by energy-dispersive X-ray spectroscopy. Results revealed a homogeneous distribution of AuNPs on the sensor surface with a dry mass coverage of 3.37 ± 1.46 µg/cm
and a contact angle of 25.2 ± 1.1°. Solid–liquid interaction studies by quartz crystal microbalance showed a high repellence of BSA from the PVP-stabilised AuNP coatings and the importance of the PVP in the mechanism of repellence. Furthermore, the conformation of the polymer on the coatings as well as its viscoelastic properties were revealed. Finally, the activated partial thrombin time test and fibrinogen adsorption studies revealed that the AuNPs do not accelerate blood coagulation and can partially inhibit the adhesion of fibrinogen, which is a crucial factor in the common blood coagulation cascade. Such AuNPs have the potential to be used in blood-contact medical applications.
Pre-twin is widely accepted as an efficient method for weakening the basal texture to improve the plasticity of magnesium alloys, particularly for formability. However, the enhancement is limited ...since the largest Schmid factor (SF) of basal slip cannot be achieved. In-plane simple shear strain is used to control the twin orientation in accordance with Schmid law to further decrease the basal texture and improve the formability of the Mg alloys sheet. Consequently, secondary regulation of initial twin orientation (SRITO) technology, a novel combination procedure, was developed. In this method, the AZ31 Mg alloys sheet is compressed to pre-twins with various volumes (1%, 3%, and 5%), then the twin orientation is regulated by in-plane simple shear strain for the second time. Compared with the as-received sample, the average fracture elongation of the annealed sample with the best properties improves from 15.3 to 28.8%, and the Erichsen value increases from 2.8 to 6.1 mm due to the regulation of twin orientation.
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Colloidal gold nanoparticles (AuNPs) were prepared from two different liquid precursors (gold (III) acetate and gold (III) chloride), using the Ultrasonic Spray Pyrolysis (USP) process. The STEM ...characterisation showed that the AuNPs from gold chloride are spherical, with average diameters of 57.2 and 69.4 nm, while the AuNPs from gold acetate are ellipsoidal, with average diameters of 84.2 and 134.3 nm, according to Dynamic Light Scattering (DLS) measurements. UV/VIS spectroscopy revealed the maximum absorbance band of AuNPs between 532 and 560 nm, which indicates a stable state. Colloidal AuNPs were used as starting material and were mixed together with acrylic acid (AA) and acrylamide (Am) for the free radical polymerization of polyacrylate-AuNPs' composites, with the purpose of using them for temporary cavity fillings in the dental industry. SEM characterisation of polyacrylate-AuNPs' composites revealed a uniform distribution of AuNPs through the polymer matrix, revealing that the AuNPs remained stable during the polymerization process. The density measurements revealed that colloidal AuNPs increase the densities of the prepared polyacrylate-AuNPs' composites; the densities were increased up to 40% in comparison with the densities of the control samples. A compressive test showed that polyacrylate-AuNPs' composites exhibited lower compressive strength compared to the control samples, while their toughness increased. At 50% compression deformation some of the samples fracture, suggesting that incorporation of colloidal AuNPs do not improve their compressive strength, but increase their toughness significantly. This increased toughness is the measured property which makes prepared polyacrylate-AuNPs potentially useful in dentistry.
Owing to the hexagonal close-packed (HCP) crystal structure inherent in Mg alloys, strong basal texture can readily be induced through the processes of rolling or extrusion. The anisotropy of the ...texture of Mg alloys impacts their stamping and forming capabilities, limiting their use in certain applications. Microalloying and shear deformation are currently the most common methods of weakening the texture of Mg alloys. Many shearing processes have been extensively studied, and given that they require complex equipment and make it difficult to achieve mass production, major attention has turned to studying the design of microalloys. Traditional trial-and-error approaches for developing micro-alloying confront many challenges, including longer test cycles and increasing expenses. The rapid advancement of big data and artificial intelligence opens up a new channel for the efficient advancement of metallic materials, specifically the application of machine learning to aid in the design of Mg alloys. ML modeling can be used to find correlations between features and attributes in data, allowing for the development and design of high-performance Mg alloys. The article provides an extensive overview of machine learning applications in Mg alloys. These include the discovery of high-performance alloys, the selection of coating designs, the design of Mg matrix composites, the prediction of second phases, the microstructure modification, optimization of rolling or extrusion parameters, and the prediction of mechanical and corrosion properties. In conclusion, challenges and prospects for the rational design of alloys with machine learning support were discussed.
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•Porous Mg monoliths with different porosities were successfully surface modified by chitosan coatings.•Chitosan coated 40% porosity monolith properties are close to the properties of ...bone, suitable candidate for biomedical application.•The corrosion studies show that chitosan coating control the degradation of magnesium.
The present study evaluates the corrosion resistance effect of chitosan coating onto porous magnesium (Mg) monoliths with porosities of 14–40 vol.%, prepared by sintering of Mg powder with NH4HCO3 used as spacer particles. The dip-coated chitosan was found to interact with corrosion products (Mg(OH)2 and MgO) via hydrogen bonding, providing the physiological stability and the corrosion resistance, at the same time affecting the mineralization process towards amorphous apatite with a small contribution of crystalline hydroxyapatite(HAP). The electrochemical studies reveal that porosity increases, and that the coating process affects the corrosion resistance positively. However, the values for compression strength (17–72MPa) and elastic modulus (12–26MPa) of chitosan-coated monolith indicate its applicability as a supporting, rather than self-standing implantation material.
The present research informs about the synthesis of gold nanoparticles (AuNPs) through Ultrasonic Spray Pyrolysis (USP), which were collected in ethanol with 0.1% Polyvinylpyrrolidone (PVP). ...Initially, the research focused on two precursors, where the first represented a homemade H-HAuCl4, completed in our own laboratory through the chlorine gas method by using HCl and KMnO4, and the second was the commercial C-HAuCl4, prepared by using Gold (III) chloride tetrahydrate powder and deionised water. The goal was to find any potential precursor differences and their influences on the later use for AuNPs synthesis through USP using almost the same parameters. In the first step of research it was determined that the H-HAuCl4 precursor was similar to C-HAuCl4 in chemical composition, surface tension and pH value. This finding represented the starting point for being able to use H-HAuCl4 in the USP for AuNPs' synthesis. In the second step, AuNPs were synthesised from both types of precursors. Afterwards, characterisation of some functional properties by FTIR and UV-vis techniques was done directly for H- and C-AuNPs in the collecting media. For SEM/EDX and TEM microscopy both types of H- and C-AuNPs were dried, and observation revealed that the morphology, shape and size distribution of dried AuNPs were very similar. Based on the performed laboratory research, it could be concluded that prepared H-AuNPs could represent a new and low-cost effective solution for future USP transfer onto the industrial level, not only in in the process itself, but also in the field of Low-cost Precursor Preparation.
Nowadays, cost-effective, available, and flexible paper-based electronics play an essential role in the electronics industry. Herein, we present gold nanoparticles (AuNPs) as a potential raw material ...for gold inks in the future for such purposes. AuNPs in this research were synthesised using the ultrasonic spray pyrolysis (USP) technique from two precursors: gold (III) chloride tetrahydrate and gold (III) acetate. Synthesised AuNPs were collected in a suspension composed of deionised (D.I.) water and the stabiliser polyvinylpyrrolidone (PVP). AuNPs' suspensions were subjected to the rotavapor process to obtain gold inks with higher Au concentration (>300 ppm). ICP-MS measurements, the size and shape of AuNPs, ζ-potential, Ultraviolet-visible (UV-Vis) spectrophotometry measurements, and scanning electron microscop y (SEM) of gold inks were carried out in order to find the optimal printing parameters. In the final stage, the optical contact angle measurements were performed using a set of polar to non-polar liquids, allowing for the determination of the surface free energy of gold inks. Inkjet printing of gold inks as defined stripes on photo paper were tested, based on the characterisation results.
This study characterized the mechanical properties of Stainless Steel PH1 (SS PH1) alloy product fabricated by Direct Metal Laser Sintering (DMLS) technique. The use of DMLS for medical, aerospace ...and automotive is attracting increasing interest due to the ability to control the stiffness of the device in the desired model. SS PH1 alloy has excellent mechanical and material properties to meet the desired character of the products in the applications mentioned above. In this research tensile test, elemental analysis and surface characterization have been performed on the samples of SS PH1 manufactured by DMLS process. The tensile properties have been tested with and without heat treatment of the tensile specimens. Energy Dispersive X-Ray Spectroscopy evaluates the elemental analyses (chemical characterization) in some areas. Surface morphology is characterized on the samples produced in different energy densities. Scanning Electron Microscope is used to analyse the fracture zone of the tensile specimens after the tensile test, micro cracks, and surface morphology. The results suggest possible innovative applications of the SS PH1 product in aerospace, automotive and biomedical implantation such as bone and dental application which can produce by DMLS process.
In the present study, the Al/Al alloy reinforced with ZrB2 composite is produced by the combination of powder metallurgy (PM) and Vacuum arc melting (VAM) techniques. The composite powder is milled ...for homogenous composition and uniaxially cold compacted to form green compacts which are used as raw materials in VAM. The composites are remelted by tumbling the melts after completion of each melt to ensure homogenous composition. The composites are then ground to the core of the melt and metallographically mirror surface finished to examine the microstructure. Secondary phase CuAl2 precipitates are formed due to the alloying effect between Cu and Al. The ZrB2 reinforcement particles existed in groups along the grain boundaries and sparsely in the bulk of the composite. The hardness increased with the alloying effect and also with the addition of ZrB2 reinforcement particles. The corrosion rate of the composite was evaluated by potentiodynamic polarization study. Corrosion rate increased with the presence of secondary phase particles.
•In this study, the Al/Al alloy reinforced with ZrB2 composite is produced.•The hardness increased with the alloying effect and also with the addition of ZrB2 reinforcement particles.•Corrosion rate increased with the presence of secondary phase particles.
•Fundamentals of supercapacitors were effectively detailed.•Fabrication of graphene-based aerogels were discussed.•Importance of electric double layer capacitors and pseudocapacitors were ...addressed.•Recent progresses of graphene-based aerogels as supercapacitors were reviewed.
Super Capacitors have attained a huge amount of attention due to their outstanding features and characteristics such as high-power density, excellent charge/discharge routine, and tendency of a longer lifetime. Graphene, a single layer of hexagonally crammed carbon atoms, has always been considered as an outstanding material for super capacitor fabrication due to its higher theoretical surface area, high electrical conductivity, stable thermal properties, and its mechanical and chemical properties. Super capacitor electrode resources which are based on 3D network/aerogel structures are resultant of graphene is a prime area of research due to their porous structure and lattice which meets the expense of rapid electron transport, higher stability, and a good cycle performance. This review intents to summarize the fundamentals and the fabrication strategies of 3D graphene aerogels.
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