In situ production of high purity noble metal nanoparticles on fumed silica and catalytic activity towards 2-nitrophenol reduction

In-situ synthesis of chemically pure noble metal (Au, Pt, Pd, Ru) nanoparticles was performed via redox reaction under ambient conditions from aqueous noble metal salt solutions on non-porous fumed silica. Nanoparticles of average sizes Au > Ru > Pt

Temperature profiling of ex-vivo organs during ferromagnetic nanoparticles-enhanced radiofrequency ablation by fiber Bragg grating arrays

In this paper, we present real-time profiles of temperature during a ferromagnetic nanoparticles (NPs)enhanced radiofrequency ablation (RFA). A minimally invasive RFA setup has been prepared and applied ex vivo on a liver phantom; NPs (with concentration of 5 mg/mL) have been synthetized and injected within the tissue prior to perform the ablation, in order to facilitate the heat distribution to the peripheral sides of the ablated tissue. Temperature detection has been realized in situ with a network of 15 fiber Bragg grating (FBG) sensors in order to highlight the impact of the NPs on the RFA mechanism. Obtained temperature profiles and thermal maps confirm that nanoparticles injection ensures better heat penetration than in case of pristine RFA procedure. The results show that adding NPs solution leads to extending the successfully ablated area achieving a double-sized lesion

Investigation of rice husk derived activated carbon for removal of nitrate contamination from water

Development of porous carbons with high specific surface area (>1200mg−1) targeted at nitrate removal from aqueous solutions is investigated by chemical activation of carbonized rice husk. Potassium carbonate is used as activating and desilicating agent. The effect of post-synthetic treatment by gas phase ammoxidation with ozone/ammonia or oxidation with concentrated nitric acid followed by nitrification with urea on main physicochemical properties and on the effectiveness of the activated carbons in nitrate removal is compared with those determined for a pristine activated carbonized rice husk sample. The two-fold enhancement of nitrate removal by the urea-modified activated carbon in comparison with pristine and ammoxidated sample is in direct correlation with the development of surface basic groups

EFFECTIVENESS OF BIO-WASTE-DERIVED CARBON DOPING ON DE-ICING PERFORMANCE OF AN ELECTRICALLY RESISTANT CONCRETE

This paper proposes a modified carbon-based concrete filler composition, which can potentially be used as a self-de-icing pavement. Carbon fibers (CNFs), graphene-like porous carbon (GLC), and a CNF/GLC composite were developed to reinforce concrete with the aim to improve its electrical conductivity and mechanical properties. The effect of the CNF and GLC loadings on the electrical conductivity of the filled concrete was evaluated in a climatic chamber at temperatures simulating water-freezing conditions on a concrete road. The results show that even a negligible loading (0.2 wt.%) of concrete with CNF/GLC results in a dramatic decrease in its resistance when compared to the same loadings for CNF and GLC added separately. Depending on the number of fillers, the temperature of the modified concrete samples reached up to +19.8 °C at low voltage (10 V) at −10 °C, demonstrating the perspective of their heat output for anti-icing applications. Additionally, this study shows that adding 2.0 wt.% of the CNF/GLC composite to the concrete improves its compressive strength by 33.93% compared to the unmodified concrete

EFFECT OF GRAPHENE OXIDE/HYDROXYAPATITE NANOCOMPOSITE ON OSTEOGENIC DIFFERENTIATION AND ANTIMICROBIAL ACTIVITY

This paper presents the fabrication and characterization of electrospun graphene oxide/calcium hydroxyapatite/polycaprolactone composite. Polycaprolactone is well-known for its excellent medical property and chemo-resistance. On the other hand graphene oxide (GO) and calcium hydroxyapatite (HAp) are both known for their superior biocompatibility, high mechanical properties, considerable electrical and thermal conductivity. Under current research GO and HAp were synthesized from an abundant bio-wastes material. As-prepared GO/HAp composite was dispersed in biodegradable polymer – polycaprolactone (PCL) in order to device a composite scaffold with the purpose to enhance osteogenic differentiation of osteoblasts for potential medical application. Synthesised composite was characterised using various chemo-physical methods. Biocompatibility was tested in the cell proliferation assay with preosteoblasts MC3T3-E1 cell line in order to identify any cytotoxic effect caused by its compounds. The bacteriostatic effect of GO was assessed using Staphylococcus aureus and Escherichia coli bacterial strains. Obtained GO/HAp/PCL composite scaffold can serve as a biologically compatible matrix for potential bone tissue regeneration with antimicrobial effect; provides an excellent biological compatibility for prospective application in medicine and clinical dentistry

Single-layer graphenes functionalized with polyurea: architectural control and biomolecule reactivity

The nondestructive, covalent reactivity of single-layer graphene oxide (SLGO) and hydrazine-reduced graphene oxide (rGO) in relation to its 3-dimensional geometry has been previously considered for various chemical reactions. However, the capability of the modified system to undergo additional chemistry is now demonstrated through an in-situ polycondensation reaction resulting in various linear or hyperbranched condensed polymers [e.g., polyureas, polyurethanes, and poly(urea–urethane)-bonded graphenes]. The use of aliphatic diisocyanates as the anchor molecule initially forms star-like clusters of SLGO and rGO, and on in-situ polycondensation reaction with aliphatic diamines, the underlying graphene architecture is further modified into scroll-like domains with extensive intersheet bridging. The use of aromatic isocyanates as bridging molecules keeps the graphene structure flat and is maintained throughout the polycondensation reaction with aromatic diamines. Critical point drying of the graphene–polymer composites shows that changes to the architecture of the composite occur in the solution phase and not through surface tension effects on drying. According to TGA analysis, the aliphatic systems have higher grafted polymer weight proportions of polyurea than the aromatic counterparts and the rGO systems are found to be greater than the SLGO composites. In all experiments, the external surface of the graphene–polyurea macrostructure is demonstrated to be reactive toward biomolecules such as ferritin and is therefore useful toward a solution chemistry development of morphology-controlled graphene-based bio-nano applications

pH driven physicochemical conformational changes of single-layer graphene oxide

Single-layer graphene oxides (SLGOs) undergo morphological changes depending on the pH of the system and may account for restricted chemical reactivity. Herein, SLGO may also capture nanoparticles through layering and enveloping when the pH is changed, demonstrating potential usefulness in drug delivery or waste material capture

Driving forces of conformational changes in single-layer graphene oxide

The extensive oxygen-group functionality of single-layer graphene oxide proffers useful anchor sites for chemical functionalization in the controlled formation of graphene architecture and composites. However, the physicochemical environment of graphene oxide and its single-atom thickness facilitate its ability to undergo conformational changes due to responses to its environment, whether pH, salinity, or temperature. Here, we report experimental and molecular simulations confirming the conformational changes of single-layer graphene oxide sheets from the wet or dry state. MD, PM6, and ab initio simulations of dry SLG and dry and wetted SLGO and electron microscopy imaging show marked differences in the properties of the materials that can explain variations in previously observed results for the pH dependent behavior of SLGO and electrical conductivity of chemically modified graphene-polymer composites. Understanding the physicochemical responses of graphene and graphene oxide architecture and performing selected chemistry will ultimately facilitate greater tunability of their performance