Project description:The unique properties of ionic liquids make them suitable candidates to prepare nanoscale materials. A simple method that uses exclusively a corresponding bulk material and an ionic liquid-in this case, [P6,6,6,14]Cl-was used to prepare AgCl nanoparticles and AgCl@Fe3O4 or TiO2@Fe3O4 magnetic nanocomposites. The prepared nanomaterials were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy. The photodegradation of atenolol as a model pharmaceutical pollutant in wastewater was investigated under ultraviolet-visible light irradiation using the different synthesized nanocatalysts. In the presence of 0.75 g·L-1 AgCl nanoparticles, a practically complete degradation of 10 ppm of atenolol was obtained after 30 min, following pseudo-first-order reaction kinetics. The effect of different variables (concentrations, pH, oxidant agents, etc.) was analyzed. The recyclability of the nanocatalyst was tested and found to be successful. A degradation mechanism was also proposed. In order to improve the recovery stage of the nanocatalyst, the use of magnetic nanocomposites is proposed. Under the same experimental conditions, a slightly lower and slower degradation was achieved with an easier separation. The main conclusions of the paper are the suitability of the use of ionic liquids to prepare different nanocatalysts and the effectiveness of these at degrading an emerging pollutant in wastewater treatment.
Project description:The current study investigates a novel redox technology based on synthetic franklinite-like zinc-ferrite nanomaterial with magnetic properties and redox nature for potential use in water treatment. Physicochemical characterization revealed the nanoscale size and AB2O4 spinel configuration of the zinc-ferrite nanomaterial. The redox activity of nanoparticles was tested for degradation of diclofenac (DCF) pharmaceutical in water, without any added external oxidants and under dark experimental conditions. Results revealed ~90% degradation in DCF (10 μM) within 2 min of reaction using 0.17 g/L Zn1.0Fe2.0O4. Degradation of DCF was due to chemical reduction by surface electrons on zinc-ferrite and oxidation by oxygen-based radicals. Three byproducts from reduction route and eight from oxidation pathways were identified in the reaction system. Reaction pathways were suggested based on the identified byproducts. Results demonstrated the magnetic zinc-ferrite is a standalone technology that has a great promise for rapid degradation of organic contaminants, such as DCF in water.
Project description:The subcellular compartments of eukaryotic cells are characterized by different redox environments. Whereas the cytosol, nucleus and mitochondria are more reducing, the endoplasmic reticulum represents a more oxidizing environment. As the redox level controls the formation of intra- and inter-molecular disulfide bonds, the folding of proteins is tightly linked to its environment. The proteostasis network of each compartment needs to be adapted to the compartmental redox properties. In addition to chaperones, also members of the thioredoxin superfamily can influence the folding of proteins by regulation of cysteine reduction/oxidation. This review will focus on thioredoxin superfamily members and chaperones of C. elegans, which play an important role at the interface between redox and protein homeostasis. Additionally, this review will highlight recent methodological developments on in vivo and in vitro assessment of the redox state and their application to provide insights into the high complexity of redox and proteostasis networks of C. elegans.
Project description:A container used in contact lens cleaning requires a Pt plating weight of 1.5 mg for H?O? decomposition although Pt is an expensive material. Techniques that decrease the amount of Pt are therefore needed. In this study, Pt nanoparticles instead of Pt plating film were supported on a substrate of acrylonitrile-butadiene-styrene copolymer (ABS). This was achieved by the reduction of Pt ions in an aqueous solution containing the ABS substrate using high-energy electron-beam irradiation. Pt nanoparticles supported on the ABS substrate (Pt-particle/ABS) had a size of 4-10 nm. The amount of Pt required for Pt-particle/ABS was 250 times less than that required for an ABS substrate covered with Pt plating film (Pt-film/ABS). The catalytic activity for H?O? decomposition was estimated by measuring the residual H?O? concentration after immersing the catalyst for 360 min. The Pt-particle/ABS catalyst had a considerably higher specific catalytic activity for H?O? decomposition than the Pt-film/ABS catalyst. In addition, sterilization performance was estimated from the initial rate of H?O? decomposition over 60 min. The Pt-particle/ABS catalyst demonstrated a better sterilization performance than the Pt-film/ABS catalyst. The difference between Pt-particle/ABS and Pt-film/ABS was shown to reflect the size of the O? bubbles formed during H?O? decomposition.
Project description:The shape-controlled synthesis of nanoparticles was established in single-phase solutions by controlling growth directions of crystalline facets on seed nanocrystals kinetically; however, it was difficult to rationally predict and design nanoparticle shapes. Here we introduce a methodology to fabricate nanoparticles in smaller sizes by evolving shapes thermodynamically. This strategy enables a more rational approach to fabricate shaped nanoparticles by etching specific positions of atoms on facets of seed nanocrystals in reverse micelle reactors where the surface energy gradient induces desorption of atoms on specific locations on the seed surfaces. From seeds of 12-nm palladium nanocubes, the shape is evolved to concave nanocubes and finally hollow nanocages in the size ~10?nm by etching the centre of {200} facets. The high surface area-to-volume ratio and the exposure of a large number of palladium atoms on ledge and kink sites of hollow nanocages are advantageous to enhance catalytic activity and recyclability.
Project description:AuNPs ranging in 20 to 300 nm size were synthesized at a room temperature using Yucca filamentosa leaf extract. Diverse nanomaterial morphologies were obtained by varying the extract concentration, reaction pH, and temperature. While low volumes of extract (0.25 and 0.5 mL) induced the formation of microscale Au sheets with edge length greater than 1 μm, high volumes yielded spherical particles ranging from 20 to 200 nm. Varying pH of the solution significantly influenced the particle shape with the production of largely spherical particles at pH 5 to 6 and truncated triangles at pH 2. Separation of multidimensional nanostructures was achieved using a novel method of sucrose density gradient centrifugation. The catalytic function of Yucca-derived AuNPs was demonstrated by degradation of a wastewater dye: methylene blue using spectrophotometric measurements over time. Treatment with Au nanosheets and spheres demonstrated methylene blue degradation approximately 100% greater than the activity in control at 60 min.
Project description:S-alkyltetrahydrothiophenium, [Cn THT]+ bis(trifluorosulfonyl)imide, [NTf2 ]- room temperature ionic liquids (ILs) and tetraphenylborate, [BPh4 ]- salts with alkyl chain lengths from C4 to C10 have been prepared. The ILs and salts were characterized and their purity verified by 1 H- and 13 C-nuclear magnetic resonance, elemental analysis, ion chromatography, Karl-Fischer titration, single crystal X-ray diffraction as well as thermogravimetric analysis. The experimentally determined density and viscosity decrease with increasing temperature. The experimental solubility of the [Cn THT][NTf2 ]-ILs in water (75 to 2.2 mg/L for C4 to C10 ) was modelled with very good agreement by Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT), based on the extremely low vapor pressures for the [Cn THT][NTf2 ]-ILs measured in this work (4.15 to 0.037 ⋅ 10-7 ×psat for C4 to C10 ). PC-SAFT is able to predict and correlate different thermodynamic properties by estimating the Helmholtz residual energy.
Project description:Xist RNA, the master regulator of X chromosome inactivation, acts in cis to induce chromosome-wide silencing. Whilst recent studies have defined candidate silencing factors, their relative contribution to repressing different genes, and their relationship with one another is poorly understood. Here we describe a systematic analysis of Xist-mediated allelic silencing in mouse embryonic stem cell-based models. Using a machine learning approach we identify distance to the Xist locus and prior gene expression levels as key determinants of silencing efficiency. We go on to show that Spen, recruited through the Xist A-repeat, plays a central role, being critical for silencing of all except a subset of weakly expressed genes. Polycomb, recruited through the Xist B/C-repeat, also plays a key role, favouring silencing of genes with pre-existing H3K27me3 chromatin. LBR and the Rbm15/m6A-methyltransferase complex make only minor contributions to gene silencing. Together our results provide a comprehensive model for Xist-mediated chromosome silencing.
Project description:In this study, natural graphite was first converted to collagen-graphene composites and then used as templates for the synthesis of nanoparticles of silver, iron oxide, and hydroxyapatite. X-ray diffraction did not show any diffraction peaks of graphene in the composites after inorganic nucleation, compared to the naked composite which showed (002) and (004) peaks. Scanning electron micrographs showed lateral gluing/docking of these composites, possibly driven by an electrostatic attraction between the positive layers of one stack and negative layers of another, which became distorted after inorganic nucleation. Docking resulted in single layer-like characteristics in certain places, as seen under transmission electron microscopy, but sp2/sp3 ratios from Raman analysis inferred three-layer composite formation. Strain-induced folding of these layers into uniform clusters at the point of critical nucleation, revealed beautiful microstructures under scanning electron microscopy. Lastly, cell viability studies using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays showed the highest cell viability for the collagen-graphene-hydroxyapatite composites. In this manner, this study provided - to the field of nanomedicine - a new process for the synthesis of several nanoparticles (with low toxicity) of high interest for numerous medical applications.
Project description:The field of conventional energy conversion using radioisotopes has almost exclusively focused on solid-state materials. Herein, we demonstrate that liquids can be an excellent media for effective energy conversion from radioisotopes. We also show that free radicals in liquid, which are continuously generated by beta radiation, can be utilized for electrical energy generation. Under beta radiation, surface plasmon obtained by the metallic nanoporous structures on TiO? enhanced the radiolytic conversion via the efficient energy transfer between plasmons and free radicals. This work introduces a new route for the development of next-generation power sources.