Magnetic photocatalysts from δ-FeOOH and TiO2 and application in reactions for degradation of methylene blue and paracetamol with UV-C and sunlight.

Water contamination is a common problem, especially considering dyes and drugs disposal. A possible and effective treatment method to remove these organic pollutants from water is photocatalytic reaction. This study aimed to improve the photocatalytic properties of TiO2 using iron oxides (Ti/Fe composite). Different magnetic photocatalysts based on commercial TiO2 were obtained with 30, 50, and 80% (wt./wt.) of TiO2 supported on maghemite. X-ray diffraction with Rietveld refinement confirms the presence of γ-Fe2O3, α-Fe2O3, anatase, and rutile, as well as the relative percentages of the phases present in each photocatalyst. The magnetic properties were certified by VSM and sedimentation kinetics in the presence of a magnetic field. Besides their magnetic properties, UV-vis DRS shows that the obtained photocatalysts presented lower bandgap values when compared with TiO2. These factors allowed the materials to absorb radiation in the visible-light region and the separation from the reaction medium by the application of magnetic field. It was observed an enhancement of photodegradation reaction of methylene blue (MB) and paracetamol (PC). For example, when the content of TiO2 increased from 30 to 80% (wt./wt.), the efficiency increased from 58 to 99% (for MB) and 39 for 80% (for PC) under UV (λ = 254 nm). The reactions carried out with solar radiation showed 56 to 95% efficiency to discolor MB. In addition, the results of sedimentation kinetics and characterization confirmed the goals of the synthesis.

Superabsorbent crosslinked carboxymethyl cellulose-PEG hydrogels for potential wound dressing applications.

This study focused on the synthesis and comprehensive characterization of environmentally friendly hydrogel membranes based on carboxymethyl cellulose (CMC) for wound dressing and skin repair substitutes. These new CMC hydrogels were prepared with two degrees of functionalization (DS=0.77 and 1.22) and chemically crosslinked with citric acid (CA) for tuning their properties. Additionally, CMC-based hybrids were prepared by blending with polyethylene glycol (PEG, 10wt.%). The results demonstrated that superabsorbent hydrogels (SAP) were produced with swelling degree typically ranging from 100% to 5000%, which was significantly dependent on the concentration of CA crosslinker and the addition of PEG as network modifier. The spectroscopical characterizations indicated that the mechanism of CA crosslinking was mostly associated with the chemical reaction with CMC hydroxyl groups and that PEG played an important role on the formation of a hybrid polymeric network. These hydrogels presented very distinct morphological features depended on the degree of crosslinking and the surface nanomechanical properties (e.g., elastic moduli) were drastically affected (from approximately 0.08GPa to 2.0GPa) due to the formation of CMC-PEG hybrid nanostructures. These CMC-based hydrogels were cytocompatible considering the in vitro cell viability responses of over 95% towards human embryonic kidney cells (HEK293T) used as model cell line.

Eco-friendly and biocompatible cross-linked carboxymethylcellulose hydrogels as adsorbents for the removal of organic dye pollutants for environmental applications.

In this study, new eco-friendly hydrogel adsorbents were synthesized based on carboxymethylcellulose (CMC, degree of substitution [DS] = 0.7) chemically cross-linked with citric acid (CA) using a green process in aqueous solution and applied for the adsorption of methylene blue (MB). Spectroscopic analyses demonstrated the mechanism of cross-linking through the reaction of hydroxyl functional groups from CMC with CA. These CMC hydrogels showed very distinct morphological features dependent on the extension of cross-linking and their nanomechanical properties were drastically increased by approximately 300% after cross-linking with 20% CA (e.g. elastic moduli from 80 ± 15 to 270 ± 50 MPa). Moreover, they were biocompatible using an in vitro cell viability assay in contact with human osteosarcoma-derived cells (SAOS) for 24 h. These CMC-based hydrogels exhibited adsorption efficiency above 90% (24 h) and maximum removal capacity of MB from 5 to 25 mg g-1 depending on the dye concentration (from 100 to 500 mg L-1), which was used as the model cationic organic pollutant. The adsorption of process of MB was well-fit to the pseudo-second-order kinetics model. The desorption of MB by immersion in KCl solution (3 mol L-1, 24 h) showed a typical recovery efficiency of over 60% with conceivable reuse of these CMC-based hydrogels. Conversely, CMC hydrogels repelled methyl orange dye used as model anionic pollutant, proving the mechanism of adsorption by the formation of charged polyelectrolyte/dye complexes.

Frontal reconstruction with frontal musculocutaneous V-Y island flap.

BACKGROUND: Defects of the frontal region are mostly caused by the ablation of tumors. When the treatment of such a defect cannot be achieved by the approximation of its margins, some of the solutions may alter the form or the continuity of the frontal aesthetic unit. METHODS: With the intent of reconstructing frontal defects with proper skin, a musculocutaneous island flap of the frontal belly of the occipitofrontalis muscle based on the supratrochlearis or the supraorbitalis vessels was planned for a V-Y application in a single procedure. It was used in 31 patients. RESULTS: The treated frontal defects ranged from 1.5 per 1.5 cm to 4.5 per 5.5 cm and, depending on the depth of the resection, exposed periosteum, bone, or dura mater. All the vessels were identified and preserved and the flaps were viable and sufficient for the defects. Three cases presented 1 cm of superficial skin necrosis with spontaneous healing that caused hypochromic scars. In eight patients the extirpation of the tumor compromised the rami temporales of the nervus facialis and caused postoperative asymmetry of the facial mimicking. All the followed patients presented normal sensitivity to touch stimuli on the flap skin and presented loss of sensitivity on the scalp distally to the flap and to the donor site. CONCLUSION: The frontal musculocutaneous island V-Y flap based on the supratrochlearis or the supraorbitalis vessels is safe and permits frontal reconstruction in a single procedure with proper maintenance of the aesthetic unit.