Stimuli-responsive synthesis of silver nanoparticles applying green and chemical reduction approaches

Introduction: The current study reports the comparative stimuli-responsive synthesis of silver nanoparticles (AgNPs) with various sizes and morphologies employing Lycium ruthenicum (L. ruthenicum) extract and sodium citrate solutions. Methods: The morphology and size of AgNPs were regulated by varying the pH values, concentrations of the extract solution, and temperatures in the reaction medium. The prepared AgNPs were assessed via various instrumental analyses, including UV-Vis, FTIR, XRD, TEM, and DLS. Results: The L. ruthenicum extract displayed several functional groups that reduced the Ag ions to the AgNPs at different values of pH. However, the primary chemical structure of L. ruthenicum was virtually unaltered at these conditions. Variations in the pH and extract concentration of the reaction medium yielded AgNPs of different sizes and morphologies. Both bio- and chemo-synthesized AgNPs revealed a relatively dispersed sphere-shaped morphology under alkaline conditions (≈ 36 nm). Conclusion: This study introduced a simple, valuable, and green technique for stimuli-sensitive AgNPs synthesis employing the L. ruthenicum extract

Bioactivity and antibacterial behaviors of nanostructured lithium-doped hydroxyapatite for bone scaffold application

The material for bone scaffold replacement should be biocompatible and antibacterial to prevent scaffold-associated infection. We biofunctionalized the hydroxyapatite (HA) properties by doping it with lithium (Li). The HA and 4 Li-doped HA (0.5, 1.0, 2.0, 4.0 wt.%) samples were investigated to find the most suitable Li content for both aspects. The synthesized nanoparticles, by the mechanical alloying method, were cold-pressed uniaxially and then sintered for 2 h at 1250 °C. Characterization using field-emission scanning electron microscopy (FE-SEM) revealed particle sizes in the range of 60 to 120 nm. The XRD analysis proved the formation of HA and Li-doped HA nanoparticles with crystal sizes ranging from 59 to 89 nm. The bioactivity of samples was investigated in simulated body fluid (SBF), and the growth of apatite formed on surfaces was evaluated using SEM and EDS. Cellular behavior was estimated by MG63 osteoblast-like cells. The results of apatite growth and cell analysis showed that 1.0 wt.% Li doping was optimal to maximize the bioactivity of HA. Antibacterial characteristics against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were performed by colony-forming unit (CFU) tests. The results showed that Li in the structure of HA increases its antibacterial properties. HA biofunctionalized by Li doping can be considered a suitable option for the fabrication of bone scaffolds due to its antibacterial and unique bioactivity properties

How should we assess knowledge translation in research organizations; designing a knowledge translation self-assessment tool for research institutes (SATORI)

<p>Abstract</p> <p>Background</p> <p>The knowledge translation self-assessment tool for research institutes (SATORI) was designed to assess the status of knowledge translation in research institutes. The objective was, to identify the weaknesses and strengths of knowledge translation in research centres and faculties associated with Tehran University of Medical Sciences (TUMS).</p> <p>Methods</p> <p>The tool, consisting of 50 statements in four main domains, was used in 20 TUMS-affiliated research centres and departments after its reliability was established. It was completed in a group discussion by the members of the research council, researchers and research users' representatives from each centre and/or department.</p> <p>Results</p> <p>The mean score obtained in the four domains of 'The question of research', 'Knowledge production', 'Knowledge transfer' and 'Promoting the use of evidence' were 2.26, 2.92, 2 and 1.89 (out of 5) respectively.</p> <p>Nine out of 12 interventional priorities with the lowest quartile score were related to knowledge transfer resources and strategies, whereas eight of them were in the highest quartile and related to 'The question of research' and 'Knowledge production'.</p> <p>Conclusions</p> <p>The self-assessment tool identifies the gaps in capacity and infrastructure of knowledge translation support within research organizations. Assessment of research institutes using SATORI pointed out that strengthening knowledge translation through provision of financial support for knowledge translation activities, creating supportive and facilitating infrastructures, and facilitating interactions between researchers and target audiences to exchange questions and research findings are among the priorities of research centres and/or departments.</p

The corrosion resistance in artificial saliva of titanium and Ti-13Nb-13Zr alloy processed by high pressure torsion

In order to optimize and enhance the implant material properties, metallic materials may be modified by severe plastic deformation (SPD) procedures. One of the most attracting SPD methods is high-pressure torsion (HPT), which is method where deformation is obtained mainly by simple shear. In the present study ultrafine-grained titanium (UFG cpTi) and ultrafine-grained Ti-13Nb-13Zr (UFG TNZ) alloy were obtained by high pressure torsion (HPT) under a pressure of 4.1 GPa with a rotational speed of 0.2 rpm up to 5 rotations at room temperature. In order to analyse microstructure of materials before and after HPT process, scanning electron microscope (SEM) was used. The aim of this study was to determine the corrosion resistance of titanium and its alloy after HPT process. Electrochemical measurements were performed in artificial saliva with a pH value of 5.5 at 37 degrees C, in order to simulate the oral environment. The materials were analysed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. All examined materials showed good corrosion resistance, but results indicate that HPT process can improves corrosion resistance

Effect of Tricalcium Magnesium Silicate Coating on the Electrochemical and Biological Behavior of Ti-6Al-4V Alloys.

In the current study, a sol-gel-synthesized tricalcium magnesium silicate powder was coated on Ti-6Al-4V alloys using plasma spray method. Composition of feed powder was evaluated by X-ray diffraction technique before and after the coating process. Scanning electron microscopy and atomic force microscopy were used to study the morphology of coated substrates. The corrosion behaviors of bare and coated Ti-6Al-4V alloys were examined using potentiodynamic polarization test and electrochemical impedance spectroscopy in stimulated body fluids. Moreover, bare and coated Ti-6Al-4V alloys were characterized in vitro by culturing osteoblast and mesenchymal stem cells for several days. Results demonstrated a meaningful improvement in the corrosion resistance of Ti-6Al-4V alloys coated with tricalcium magnesium silicate compared with the bare counterparts, by showing a decrease in corrosion current density from 1.84 μA/cm2 to 0.31 μA/cm2. Furthermore, the coating substantially improved the bioactivity of Ti-6Al-4Valloys. Our study on corrosion behavior and biological response of Ti-6Al-4V alloy coated by tricalcium magnesium silicate proved that the coating has considerably enhanced safety and applicability of Ti-6Al-4V alloys, suggesting its potential use in permanent implants and artificial joints

Morphology of the cells on the surface of the bare Ti-6Al-4V alloy (a) and the Ti-6Al-4V alloy coated with tricalcium magnesium silicate (b, c) after 5 d of culture.

<p>Morphology of the cells on the surface of the bare Ti-6Al-4V alloy (a) and the Ti-6Al-4V alloy coated with tricalcium magnesium silicate (b, c) after 5 d of culture.</p

Characterization and optical properties of mechanochemically synthesized molybdenum-doped rutile nanoparticles and their electronic structure studies by density functional theory

The optical and electronic properties of molybdenum (Mo) doped rutile TiO2 prepared by the mechanochemical method were studied both experimentally and using density functional theory (DFT). The synthesized nanoparticles were characterized by XRD, TEM, EDS-MAP, and XPS. The XRD results showed the successful incorporation of Mo in the rutile crystal lattice. High-resolution TEM images illustrated a decreasing trend in the (110) d-spacing for samples doped up to 3 at%. The shift toward higher binding energies in the XPS spectra was due to the higher oxidization tendencies of Mo5+ and Mo6+ substituted in Ti4+ sites. The optical behavior of samples was examined by UV–Vis and photoluminescence spectroscopy. The bandgap energy value of rutile was reduced from 3.0 eV to 2.4 eV by 2 at% Mo doping. The DFT calculations showed a reduction of bandgap energy value of rutile to 2.35 eV with 2 at% Mo, which is in harmony with the experimental results. The creation of energy states below the conduction band because of Mo doping was identified as the reason for reducing the bandgap energy and photoluminescence emission of rutile