In the field of synthesis and processing of noble metal nanoparticles, the study of the bottom-up method, called Ultrasonic Spray Pyrolysis (USP), is becoming increasingly important. This review ...analyses briefly the features of USP, to underline the physical, chemical and technological characteristics for producing nanoparticles and nanoparticle composites with Au and Ag. The main aim is to understand USP parameters, which are responsible for nanoparticle formation. There are two nanoparticle formation mechanisms in USP: Droplet-To-Particle (DTP) and Gas-To-Particle (GTP). This review shows how the USP process is able to produce Au, Ag/TiO2, Au/TiO2, Au/Fe2O3 and Ag/(Y0.95 Eu0.05)2O3 nanoparticles, and presents the mechanisms of formation for a particular type of nanoparticle. Namely, the presented Au and Ag nanoparticles are intended for use in nanomedicine, sensing applications, electrochemical devices and catalysis, in order to benefit from their properties, which cannot be achieved with identical bulk materials. The development of new noble metal nanoparticles with USP is a constant goal in Nanotechnology, with the objective to obtain increasingly predictable final properties of nanoparticles.
Monitoring of the corrosion process of alloys in real conditions often results in extensive data, which is characterized by complex interdependence, but by a large degree of mutual deviation. First ...of all, the large dispersion of the obtained results makes it very difficult to draw accurate conclusions about the real influence of the tested parameters on the corrosion behavior of alloys. On the other hand, in many cases, the high interdependence between the corrosion factors can also greatly burden the analyzed system and thus make it significantly difficult to recognize the main influence. Multivariate analysis, especially the principal component analysis, is becoming increasingly popular in processing of this type of data, due to its ability to recognize and eliminate redundant data. The aim of this study was to examine the possibility of using multivariate analysis methods in the processing of the corrosion test results obtained under real conditions. Based on the obtained results, it can be concluded that used multivariate method in combination with energy dispersive spectrometer analysis can be successfully used to identify the most important corrosion factors (type of corrosion environment, exposure time and technological production processes), as well as their influence on the degradation of the tested TiNi alloys under the given conditions.
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.
A stone chest found in 1971 near one of the largest early Christian basilicas in Northern Dalmatia (Croatia) contained brass tiles decorated with various biblical scenes. An archaeological study ...confirmed the thesis that the fragments of brass tiles are most likely the remains of a wooden chest made in the 4th century AD, and that this is one of the best preserved archaeological finds of its kind in the world as one of the biblical scenes shows Mary, together with a record of her name (Maria). Based on the preserved brass tiles, a reconstruction of the wooden chest was made in 1973 with tiles glued onto a plastic frame. Subsequent studies have shown that such a reconstruction was not adequate, as some of the brass tiles were destroyed (disintegrated), and they were not connected properly into a whole that could represent the original. For the new reconstruction of this archaeological object it was necessary to carry out a material analysis, including the chemical composition of the brass tiles, as well as to find a solvent for the glue which could be used to remove the brass tiles from the plastic framework without any additional destruction. Based on extensive investigations and material analyses including the following techniques (SEM, EDX, FTIR, DSC), the starting points for the restoration process of the wooden chest with brass tiles were set, as well as the proposal for the appearance of the new chest.
The aim of this study was to investigate and understand bacterial adhesion to different dental material surfaces like amalgam, Chromasit, an Co-Cr alloy, an IPS InLine ceramic, yttrium stabilized ...tetragonal polycrystalline zirconia (TPZ), a resin-based composite, an Au-Pt alloy, and a tooth. For all materials, the surface roughness was assessed by profilometry, the surface hydrophobicity was determined by tensiometry, and the zeta potential was measured by electrokinetic phenomena. The arithmetic average roughness was the lowest for the TPZ ceramic (R
= 0.23 µm ± 0.02 µm), while the highest value was observed for the Au-Pt alloy (R
= 0.356 µm ± 0.075 µm). The hydrophobicity was the lowest on the TPZ ceramic and the highest on the Co-Cr alloy. All measured streaming potentials were negative. The most important cause of tooth caries is the bacterium
, which was chosen for this study. The bacterial adhesion to all material surfaces was determined by scanning electron microscopy. We showed that the lowest bacterial extent was on the amalgam, whereas the greatest extent was on tooth surfaces. In general, measurements showed that surface properties like roughness, hydrophobicity and charge have a significant influence on bacterial adhesion extent. Therefore, dental material development should focus on improving surface characteristics to reduce the risk of secondary caries.
To monitor the progress and prevent the spread of the COVID-19 pandemic in real time and outside laboratories, it is essential to develop effective tests that can ensure rapid, selective, and ...reliable diagnosis of infected persons in different environments. Key in this regard is the lateral flow immunoassays (LFIAs) that can detect the presence of the SARS-CoV-2 virus quickly, with the aid of nanoparticles (NPs) and specific proteins. We report the use of gold (Au) NPs AuNPs synthesised from a gold(
) chloride tetrahydrate precursor in a USP device and collected in a suspension composed of deionised water with polyvinylpyrrolidone as a stabiliser and cryoprotectant. In combination with freeze-drying of the AuNPs’ suspension to achieve water elimination, improved stability, and the target concentration, they exhibit the necessary properties for use as markers in LFIA rapid diagnostic tests. This was confirmed by complementary characterisation determined by using the techniques including inductively coupled plasma-optical emission spectrometry, dynamic light scattering method and zeta-potential, ultraviolet-visible spectroscopy, X-ray diffraction, scanning electron microscopy with energy dispersion spectrometer, and transmission electron microscopy, as well as with the preparation of a prototype LFIA test strip with AuNPs. Thus, such AuNPs, as well as the USP method, show promise for the development of new markers for use in LFIA.
A complex concentrated noble alloy (CCNA) of equiatomic composition (Ag20Pd20Pt20Cu20Ni20–20 at. %) was studied as a potential high—performance material. The equiatomic composition was used so that ...this alloy could be classified in the subgroup of high—entropy alloys (HEA). The alloy was prepared by induction melting at atmospheric pressure, using high purity elements. The degree of metastability of the cast state was estimated on the basis of changes in the microstructure during annealing at high temperatures in a protective atmosphere of argon. Characterisation of the metallographically prepared samples was performed using a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), differential scanning calorimetry (DSC), and X–ray diffraction (XRD). Observation shows that the microstructure of the CCNA is in a very metastable state and multiphase, consisting of a continuous base of dendritic solidification—a matrix with an interdendritic region without other microstructural components and complex spheres. A model of the probable flow of metastable solidification of the studied alloy was proposed, based on the separation of L—melts into L1 (rich in Ni) and L2 (rich in Ag). The phenomenon of liquid phase separation in the considered CCNA is based on the monotectic reaction in the Ag−Ni system.
Lateral flow immunoassays (LFIAs) are a simple diagnostic device used to detect targeted analytes. Wasted and unused rapid antigen lateral flow immunoassays represent mass waste that needs to be ...broken down and recycled into new material components. The aim of this study was to recover gold nanoparticles that are used as markers in lateral flow immunoassays. For this purpose, a dissolution process with aqua regia was utilised, where gold nanoparticles were released from the lateral flow immunoassay conjugate pads. The obtained solution was then concentrated further with gold chloride salt (HAuCl4) so that it could be used for the synthesis of new gold nanoparticles in the process of ultrasonic spray pyrolysis (USP). Various characterisation methods including scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy and optical emission spectrometry with inductively coupled plasma were used during this study. The results of this study showed that the recovery of gold nanoparticles from lateral flow immunoassays is possible, and the newly synthesised gold nanoparticles represent the possibility for incorporation into new products.
Mineral wool made from basalt fibers is frequently used as an insulating material in construction systems. In this study, both unused mineral wool and wool obtained from the softened roofing area ...were comprehensively analyzed in a laboratory using different characterization techniques. Firstly, the initial water content and compressive strength at 10% deformation were determined. Secondly, microstructure and surface chemical composition were analyzed by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDX). To study heterogeneities near the fiber surface and to examine cross-sectional composition, a scanning transmission electron microscope (STEM) was used. Finally, to verify possible reasons for resin degradation, thermogravimetric analysis and differential scanning colometry (TGA-DSC) were simultaneously carried out. The results show that natural aging under high humidity and thermal fluctuations greatly affected the surface morphology and chemical composition of the fibrous composite. Phenol-formaldehyde and other hydrophobic compounds that protect fibers against moisture and give compressive resistance were found to be degraded.
The Ni/Y2O3 catalyst showed high catalytic activity. Based on this, the aim of this study was to create Ni/Y2O3 nanocomposites powder with two innovative technologies, Ultrasonic Spray Pyrolysis ...(USP) and lyophilisation. In the USP process, thermal decomposition of the generated aerosols in an N2/H2 reduction atmosphere caused a complete decomposition of the nickel (II) nitrate to elemental Ni, which became trapped on the formed Y2O3 nanoparticles. The Ni/Y2O3 nanocomposite particles were captured via gas washing in an aqueous solution of polyvinylpyrrolidone (PVP) in collection bottles. PVP was chosen for its ability to stabilise nano-suspensions and as an effective cryoprotectant. Consequently, there was no loss or agglomeration of Ni/Y2O3 nanocomposite material during the lyophilisation process. The Ni/Y2O3 nanocomposite powder was analysed using ICP-MS, SEM-EDX, and XPS, which showed the impact of different precursor concentrations on the final Ni/Y2O3 nanocomposite particle composition. In a final step, highly concentrated Ni/Y2O3 nanocomposite ink (Ni/Y2O3 > 0.140 g/mL) and test coatings from this ink were prepared by applying them on a white matte photo paper sheet. The reflection curve of the prepared Ni/Y2O3 nanocomposite coating showed a local maximum at 440 nm with a value of 39% reflection. Given that Ni is located on the surface of the Ni/Y2O3 nanocomposite in the elemental state and according to the identified properties, tests of the catalytic properties of this coating will be performed in the future.
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