Plasma-Driven Tuning of Dielectric Permittivity in Graphene.

Materials with tunable negative electromagnetic performance, i.e., where dielectric permittivity becomes negative, have long been pursued in materials research due to their peculiar electromagnetic (EM) characteristics.

Valorisation of spent tire rubber as carbon adsorbents for Pb(II) and W(VI) in the framework of a Circular Economy.

Spent tire rubber-derived chars and their corresponding HPO and CO-activated chars were used as adsorbents in the recovery of Pb(II) ion and (W(VI)) oxyanion from synthetic solutions. The developed chars (both raw and activated) were thoroughly characterized to have insight about their textural and surface chemistry properties. HPO-activated chars presented lower surface areas than the raw chars and an acidic surface chemistry which affected the performance of these samples as they showed the lowest removals of the metallic ions.

Bactericide Activity of Cellulose Acetate/Silver Nanoparticles Asymmetric Membranes: Surfaces and Porous Structures Role.

The antibacterial properties of cellulose acetate/silver nanoparticles (AgNP) ultrafiltration membranes were correlated with their integral asymmetric porous structures, emphasizing the distinct features of each side of the membranes, that is, the active and porous layers surfaces. Composite membranes were prepared from casting solutions incorporating polyvinylpyrrolidone-covered AgNP using the phase inversion technique. The variation of the ratio acetone/formamide and the AgNP content resulted in a wide range of asymmetric porous structures with different hydraulic permeabilities.

Cotton decorated with CuO-Ag and CuO-Ag-AgBr NPs via an in-situ sacrificial template approach and their antibacterial efficiency.

Cotton fabrics decorated with CuO-Ag and CuO-Ag-AgBr NPs have been prepared using chemically immobilized CuO NPs as sacrificial templates. The objective is to prepare CuO-Ag heterostructures with Ag being intimately in contact with CuO NPs by galvanic replacement reactions without addition of any external reducing agent. Field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis were used to study the morphology and the chemical composition of the nanocomposites formed on the fabrics.

Preclinical In Vitro Assessment of Submicron-Scale Laser Surface Texturing on Ti6Al4V.

Loosening of orthodontic and orthopedic implants is a critical and common clinical problem. To minimize the numbers of revision surgeries due to peri-implant inflammation or insufficient osseointegration, developments of new implant manufacturing strategies are indicated. Ultrafast laser surface texturing is a promising contact-free technology to modify the physicochemical properties of surfaces toward an anti-infectious functionalization.

Cotton fabrics decorated with nanostructured Ag/AgX (X:Cl,Br) as reusable solar light-mediated bactericides: A comparative study.

In this study, cotton fabrics decorated with Ag/AgCl and Ag/AgBr NPs were produced by a simple hydrothermal treatment using AgCl and AgBr as precursors. Their morphological features as well as, chemical composition and structural and luminescence properties were compared. Their water disinfection aptitude against E.

Silver Nanoparticles on Cellulose Surfaces: Quantitative Measurements.

In this work, cellulose films pre-activated with carbonyldiimidazole (CDI) and grafted with 1,6-hexanediamine, were decorated with silver nanoparticles (AgNPs). The generation of AgNPs was followed by quartz crystal microbalance (QCM). The obtained films were characterized by X-Ray Photoelectron Spectroscopy (XPS) and imaged by atomic force microscopy (AFM).

Hybrid chitosan-TiO/ZnS prepared under mild conditions with visible-light driven photocatalytic activity.

Thin films of chitosan (CS) coated on glass substrates were used as support for the immobilization of nanostructures TiO/ZnS via a mild chemical process followed by a hydrothermal treatment at 90 °C. The preparation route involved the coating of the CS film on the glass substrate followed by the deposition of a thin layer of Ti(OBu) precursor and immersion in a solution of Zn(OCCH) and NaS. After a hydrothermal treatment at 90 °C, an even layer of TiO anatase decorated by ZnS nanorods was generated.

Unraveling the reaction mechanism of silver ions reduction by chitosan from so far neglected spectroscopic features.

Metallic silver nanoparticles were synthesized in aqueous solution using chitosan, as both reducing and stabilizing agent, and AgNO as silver precursor aiming the production of solid ultra-thin films. A systematic characterization of the resulting system as a function of the initial concentrations was performed. The combination of UV-vis absorption - and its quantitative analysis - with X-ray photoelectron spectra, light scattering measurements and atomic force microscopy allowed obtaining a rational picture of silver reduction mechanism through the identification of the nature of the formed reduced/oxidized species.

Human mesenchymal stem cell behavior on femtosecond laser-textured Ti-6Al-4V surfaces.

Aim: The aim of the present work was to investigate ultrafast laser surface texturing as a surface treatment of Ti-6Al-4V alloy dental and orthopedic implants to improve osteoblastic commitment of human mesenchymal stem cells (hMSCs).

Materials & Methods: Surface texturing was carried out by direct writing with an Yb:KYW chirped-pulse regenerative amplification laser system with a central wavelength of 1030 nm and a pulse duration of 500 fs. The surface topography and chemical composition were investigated by scanning electron microscopy and x-ray photoelectron spectroscopy, respectively.

Hybrid systems of silver nanoparticles generated on cellulose surfaces.

A method to produce hybrid systems of cellulose ultrathin films containing immobilized silver nanoparticles (Ag NPs) generated and grown at the surface is presented. Ag NPs were produced via a mild wet chemistry technique on cellulose ultrathin films spin-coated on GaAs substrates and on modified films after grafting of diaminoalkanes activated by N,N'-carbonyldiimidazole. Appended amine groups operate as anchoring centers of the silver NPs enabling selective generation and immobilization of Ag NPs.

Physical immobilization of Rhizopus oryzae lipase onto cellulose substrate: activity and stability studies.

Rhizopus oryzae lipase (ROL) was immobilized by adsorption onto oxidized cellulose fibers and regenerated films. The maximum adsorption level increases with the raise in the amount of carboxylic groups on cellulose surface confirming that adsorption is being governed mainly by electrostatic interaction between the enzyme and the substrate. This hypothesis was further confirmed by zeta-potential measurements showing a decrease in the zeta-potential of the fibers after enzyme adsorption.

Grafting of porphyrins on cellulose nanometric films.

Ultrathin films of cellulose were functionalized with iron protoporphyrin IX (FePP). Spin-coating allows the production of silylated cellulose films in a controlled way. Cellulose regeneration is achieved through the hydrolyzation of the silane groups, exposing the film to acidic vapors.

Counterions in layer-by-layer films--influence of the drying process.

The amount of counterions, measured by means of X-ray photoelectron spectroscopy (XPS), in layer-by-layer (LbL) films of poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS), prepared from solutions with various NaCl concentrations, is shown to be greatly influenced by the film drying process: a smaller amount of counterions is observed in films dried after adsorption of each layer, when compared with films that were never dried during the film preparation. This is attributed to the formation of NaCl nanocrystals during the drying process which dissolve when the film is again immersed in the next polyelectrolyte solution. The presence of bonded water molecules was confirmed in wet films indicating that the counterions near the ionic groups are immersed in a water network.

Counterions in poly(allylamine hydrochloride) and poly(styrene sulfonate) layer-by-layer films.

The amount of counterions in layer-by-layer (LBL) films of poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) has been determined with X-ray photoelectron spectroscopy (XPS) for films prepared from solutions with various NaCl concentrations. Sodium and chloride counterions are present in LBL films produced from salt solutions, which are located at the surface and in the bulk of the films. The percentage of bulk counterions increases with the ionic strength of the polyelectrolyte before reaching a constant value.