Abstract  Vanadium oxide, supported on zinc oxide (ZnO), was prepared and used as a catalyst to enforce terephthalic acid (TA) elimination, using photocatalytic ozonation based on light emission diodes (UV-ALEDs). The catalyst characterization indicated that vanadium oxide was not incorporated into the pores of zinc oxide, due to the formation of thinner flakes. The synthesized catalyst exhibited high stability, because no significant changes between fresh and used catalyst were confirmed by the XPS results. All variants of ozonation (conventional, catalytic, and photocatalytic) removed the terephthalic acid completely during 60 min; however, its reaction rate constant was higher in the catalytic and photocatalytic ozonation (22% and 25%, respectively). The ozone decomposition study indicated that terephthalic acid was degraded by the combined action of molecular ozone and hydroxyl radicals. The latter oxidant species play an important role in promoting the byproduct elimination generated during the ozonation of TA. The distribution of UV-ALEDs was evaluated in two configurations (central and external irradiation), which resulted in significant differences. These differences were confirmed by the reaction rates of the byproducts accumulation and their decomposition. Even when the energy supplied in both cases remained constant (4 W m(-2)), the interaction between photons and active sites in the catalyst was twice higher, when the UV-ALEDs were on the peripheral of the reactor. All these results show that VxOy/ZnO is a potential catalyst for photocatalytic ozonation using a portion of the visible electromagnetic spectrum.

Abstract  In vitro studies showed that high-frequency pulsed electromagnetic fields (HF-PEMFs) increase the activity/expression of early and late osteogenic markers and enhance bone mineralization. The main aim of this study was to investigate the in vivo effects of HF-PEMFs on fracture healing using a rat model. A femur fracture was established by surgery in 20 male Wistar rats. Titanium nails were implanted to reduce and stabilize the fracture. After surgery, 20 rats were equally divided into untreated control and treated group (from the first postoperative day HF-PEMFs at 400 pulses/sec [pps] were applied for 10 minutes/day, for two weeks). Quantitative and qualitative assessment of bone formation was made at two and eight weeks following surgery and included morphological and histological analysis, serological analysis by ELISA, micro-computed tomography (micro-CT), and three-point bending test. At two weeks in HF-PEMF group, soft callus was at a more advanced fibrocartilaginous stage and the bone volume/total tissue volume (BV/TV) ratio in the callus area was significantly higher compared to control group (p = 0.047). Serum concentration of alkaline phosphatase (ALP) and osteocalcin (OC) was significantly higher in HF-PEMF group (ALP p = 0.026, OC p = 0.006) as well as the mechanical strength of femurs (p = 0.03). At eight weeks, femurs from HF-PEMF group had a completely formed woven bone with dense trabeculae, active bone marrow, and had a significantly higher BV/TV ratio compared to control (p = 0.01). HF-PEMFs applied from the first postoperative day, 10 minutes/day for two weeks, enhance bone consolidation in rats, especially in the early phase of fracture healing.

Abstract  Response surface methodology was applied to optimize the processing parameters (dosage of NaOH, dosage of H2O2, reaction temperature, liquid-to-solid ratio, stirring rate, and reaction time) that affected the leaching process of vanadium and chromium. The results indicated that the leaching process of vanadium was significantly affected by the dosage of NaOH and dosage of H2O2 used in the experiments, whereas the processing parameters affected the leaching efficiency of chromium in the following order: dosage of H2O2 (F) > reaction temperature (C) > dosage of NaOH (A) > reaction time (B) > stirring rate (D) > liquid-to-solid ratio (E). Almost 98.60% of vanadium and 79.82% of chromium were leached out during the leaching process.