Graphene Oxide Carboxymethylcellulose Nanocomposite for Dressing Materials

Sore, infected wounds are a major clinical issue, and there is thus an urgent need for novel biomaterials as multifunctional constituents for dressings. A set of biocomposites was prepared by solvent casting using different concentrations of carboxymethylcellulose (CMC) and exfoliated graphene oxide (Exf-GO) as a filler. Exf-GO was first obtained by the strong oxidation and exfoliation of graphite. The structural, morphological and mechanical properties of the composites (CMCx/Exf-GO) were evaluated, and the obtained composites were homogenous, transparent and brownish in color. The results confirmed that Exf-GO may be homogeneously dispersed in CMC. It was found that the composite has an inhibitory activity against the Gram-positive Staphylococcus aureus, but not against Gram-negative Pseudomonas aeruginosa. At the same time, it does not exhibit any cytotoxic effect on normal fibroblasts

Size-Dependent Persistent Luminescence of YAGG:Cr3+ Nanophosphors

In the current work, YAGG:Cr3+ nanophosphors were synthesized by the Pechini method and then annealed at different temperatures in the range 800–1300 °C. The structure and morphology of the samples were characterized by X-ray Powder Diffraction (XRPD). The lattice parameters and average crystalline sizes as site occupation by Al3+ and Ga3+ ions were calculated from the Rietveld refinement data. To investigate the effect of crystalline size of the materials on their optical properties: excitation and emission spectra were recorded and analyzed. Finally, the effect of crystalline size on the probability of carrier recombination leading to PersL was determined experimentally with thermoluminescence analyses. The Tmax-Tstop method was applied to determine the trap type and particle size (calcination temperature) effect on their redistribution. A correlation between structural changes and trap redistribution was found. In particular, the extinction of high-temperature TL maximum with increasing annealing temperatures is observed, while low-temperature TL maximum increases and reaches a maximum when the lattice parameter reaches saturation

Up-converting ALD/MLD thin films with Yb3+, Er3+ in amorphous organic framework

openaire: EC/H2020/339478/EU//LAYERENG-HYBMATNear-infrared to green and red up-conversion is reported for a new type of hybrid (Yb,Er)-IR-806 films prepared using the atomic/molecular layer deposition (ALD/MLD)thin-film fabrication technology. These amorphous films can be realized in controllable nanothicknesses and they show an exceptionally wide absorption band in the near-infrared region. The films exhibit a highly local up-conversion excitation process, which suggests strong potential for use as e.g. temperature sensors with Ångström scale surface resolution.Peer reviewe

Urea Glass Route as a Way to Optimize YAGG:Ce3+,Cr3+,Pr3+ Nanocrystals for Persistent Luminescence Applications

A new approach for the synthesis of Y3Al2Ga3O12 (YAGG) nanophosphors allowing the preparation of crystallites with sizes starting from 45 nm is presented. The controllability of the energy and trap density of the resulting material samples by annealing temperature was confirmed by thermoluminescence (TL) measurements. It has been shown that the annealing of samples at temperatures up to 1300 degrees C does not cause any substantial growth of crystallites, still remaining below 100 nm, but leads to changes in the activation energy of the persistent luminescence (PersL) process. On the other hand, annealing above 1400 degrees C results in grain growth on the submicron scale, which was confirmed by X-ray powder diffraction (XRPD) and electron transmission microscopy (TEM) measurements. In addition, with an increase in the molar ratio of urea to the total amount of metals used (R), qualitative changes are observed in the PersL process occurring from the excited states of Cr3+ and Pr3+ ions. This proves the influence of the synthesis process, in particular of the metal complexation at its initial stage, on the final structure ordering in the annealed materials. These observations are linked to previously reported defects in the YAGG structure, leading to PersL

Fabrication and properties of pink 3 mol% yttria‐stabilized zirconia ceramics with high toughness

To broaden the applications of yttria-stabilized zirconia (YSZ) in mobile phone back panels and high-end decorative materials, the 3 mol% YSZ (3YSZ) ceramics doped with erbium oxide (Er2O3) as colorant were successfully sintered at 1250 and 1350°C in air. The influences of Er2O3-doping concentration and sintering temperature on the phase, microstructure, color, and mechanical properties of the pink Er2O3-3YSZ ceramics were investigated. As the Er2O3 concentration increased, the redness value a* gradually increased, while the yellowness value b* and the lightness value L* gradually decreased. The highest value a* and b* of Er2O3-3YSZ ceramics reached absolute values of 15.2 and 4.5, respectively. The effect of Er2O3 concentration is also depicted in detail, which also affects the mechanical properties including hardness and fracture toughness of the ceramics. The maximum hardness and fracture toughness of Er2O3-3YSZ ceramics reached 13.9 ± 0.3 GPa and 6.21 ± 0.20 MPa·m1/2, respectively. The hardness of the ceramics exceeds 12.5 GPa, which is the required market index for further practical application. This work provides a method for preparing 3YSZ ceramics with excellent mechanical properties and bright pink color, which has the potential to be used in the fields of advanced and superior electronics in particular

Gallato Zirconium (IV) Phtalocyanine Complex Conjugated with SiO₂ Nanocarrier as a Photoactive Drug for Photodynamic Therapy of Atheromatic Plaque

A new conjugate of gallato zirconium (IV) phthalocyanine complexes (PcZrGallate) has been obtained from alkilamino-modified SiO2 nanocarriers (SiO2-(CH2)3-NH2NPs), which may potentially be used in photodynamic therapy of atherosclerosis. Its structure and morphology have been investigated. The photochemical properties of the composite material has been characterized. in saline environments when exposed to different light sources Reactive oxygen species (ROS) generation in DMSO suspension under near IR irradiation was evaluated. The PcZrGallate-SiO2 conjugate has been found to induce a cytotoxic effect on macrophages after IR irradiation, which did not correspond to ROS production. It was found that SiO2 as a carrier helps the photosensitizer to enter into the macrophages, a type of cells that play a key role in the development of atheroma. These properties of the novel conjugate may make it useful in the photodynamic therapy of coronary artery disease