Selective oxidation processes of organic substances in water by means of photocatalytic systems

Selective oxidation of benzyl alcohol into benzaldehyde in anoxic acidic aqueous solution, through a TiO2/Cu(II)/solar UV photocatalytic system, has been investigated both in a laboratory scaled reactor equipped with a high-pressure mercury lamp as well as in a solar pilot plant. During the laboratory experiments, benzaldehyde gave best results, in terms of yield, equal to 35% with respect to the initial benzyl alcohol concentration. A partial conversion of benzaldehyde to benzoic acid has also been observed. Traces of hydroxylated by-products have also been detected. On the basis of the formation of these species, a production of HO radicals has been thus inferred. The study has suggested that different operative parameters, such as the composition and amount of TiO2 photocatalyst, pH, ionic inorganic components in water, and the initial concentration of Cu(II) ions, play an important role in the photocatalytic selective oxidation of benzyl alcohol. The mechanism of photocatalytic selective oxidation of benzyl alcohol into benzaldehyde and benzaldehyde into benzoic acid has been investigated in the presence of TiO2 catalyst and cupric ions, as electron acceptor, in water at a pH = 2.0 and under deaerated conditions. A competitive adsorption has been proposed in which the aromatic substrates are adsorbed on the TiO2 surface and react with the positive holes. Whereas Cu(II) ions are reduced to Cu(0) by the photogenerated electrons. A new kinetic model has been developed by writing a set of mass balance equations for the main species involved in the photocatalytic oxidation process. The resulting mathematical model has been used for the analysis of the data collected at different starting substrates’ concentrations. During each of the selective photoxidation runs, it satisfactorily predicts the concentrations of Cu(II) species, organic substrates, and intermediates. The effect of ionic components, which compete with benzyl alcohol and benzaldehyde for the reaction with positive holes on the catalyst surface and behave as scavengers towards HO radicals, has been taken into account in the model. The values of some rate constants of the reactions of the holes with benzyl alcohol, benzaldehyde, Cu(II) species, and inorganic anions (sulfates and di-hydrogenophosphates), not available in the literature, have been estimated by a proper optimizing procedure. 7 The conversion of hydroxybenzyl alcohols, methoxybenzyl alcohols and nitrobenzyl alcohol into the corresponding aldehydes has been attempted by using the same process. The presence and position of substituent groups in the aromatic alcohols structure change the photocatalytic oxidation rates and product selectivities with respect to that previously observed for unsubstituted benzyl alcohol. In particular, the presence of both electron donating (hydroxy, methoxy groups) and electron withdrawing (nitro group) on the aromatic ring of the substrate causes a detrimental effect on the selectivity of the process with respect to that of benzyl alcohol. The technical feasibility of selective photocatalytic oxidation of benzyl alcohol to benzaldehyde, in aqueous solutions and in presence of cupric ions, has been then investigated in a solar pilot plant with Compound Parabolic Collectors. Under deaerated conditions, the presence of reduced copper species has been proved by XPS analysis. The results indicated that, at the end of the process, cupric species can be easily regenerated and reused, through a re-oxidation of reduced copper that is produced during the photolytic run, with air or oxygen in dark conditions. A figure-of-merit (ACM), proposed by the International Union of Pure and Applied Chemistry (IUPAC) and based on the collector area, has been estimated, under the proposed conditions, with the aim to provide a direct link to the solar-energy efficiency independently of the nature of the system. Generally speaking, it can be considered that the lower ACM values are, the higher is the system efficiency

Flap reconstruction of the hypopharynx: a defect orientated approach

The present retrospective analysis evaluated the outcomes of different flap reconstructions for several hypopharyngeal defects in 136 patients who underwent hypopharyngeal reconstruction with a free or pedicled flap after excision of pharyngeal or laryngeal carcinoma.Functional and oncological outcome were the main measures. Nine patients had a type I-a hypopharyngeal defect (partial with larynx preserved), 33 type I-b (partial without larynx preserved), 85 type II (circumferential), 5 type III (extensive superior) and 4 vertical hemipharyngolaryngectomy. The flaps used to reconstruct these defects were pectoralis major (n = 34), free radial forearm (n = 25), jejunum (n = 72), pedicled latissimus dorsi (n = 2), sternocleidomastoid (n = 1), lateral thigh (n = 1) and deltopectoral (n = 1). Twelve defects (9%) needed a secondary flap reconstruction. Surgical and medical complications were seen in 29% and 8% of patients, respectively; 18% of patients developed a fistula. No difference in complication rate or admission days was found for pre-operative versus no previous radiotherapy, type of defect or free versus pedicled flap. After 12 months follow-up, 38% of patients had a tracheo-oesophageal voice prosthesis, in 82% a fully oral diet was obtained and the average body weight gain was 0.9 kg. Five-year overall and disease-specific survival rates were 35% and 49%, respectively, while local and regional control rates were 65% and 91%, respectively. Considering these results, a defect orientated approach may be helpful for deciding which flap should be used for reconstruction of the hypopharynx. An algorithm is proposed with similar functional and oncological outcomes for the different groups. The choice of flap should be based on expected morbidity and functional outcome

Methyl orange photo‐degradation by tio2 in a pilot unit under different chemical, physical, and hydraulic conditions

The photo‐catalytic degradation of a textile azo‐dye as Methyl Orange was studied in an innovative unit constituted by a channel over which a layer of titanium dioxide (TiO2) catalyst in anatase form was deposited and activated by UVB irradiation. The degradation kinetics were followed after variation of the chemical, physical, and hydraulic/hydrodynamic parameters of the system. For this purpose, the influence of the TiO2 dosage (g/cm3), dye concentration (mg/L), pH of the solution, flow‐rate (L/s), hydraulic load (cm), and irradiation power (W) were evaluated on the degradation rates. It was observed that the maximum dosage of TiO2 was 0.79 g/cm3 while for higher dosage a reduction of homogeneity of the cement conglomerate occurred. The Langmuir– Hinshelwood (LH) kinetic model was followed up to a dye concentration around 1 mg/L. It was observed that with the increase of the flow rate, an increase of the degradation kinetics was obtained, while the further increase of the flow‐rate associated with the modification of the hydraulic load determined a decrease of the kinetic rates. The results also evidenced an increase of the kinetic rates with the increase of the UVB intensity. A final comparison with other dyes such as Methyl Red and Methylene Blue was carried out in consideration of the pH of the solution, which sensibly affected the removal efficiencies

Early thromboelastography in acute traumatic coagulopathy: an observational study focusing on pre-hospital trauma care

Background: Major brain injury and uncontrolled blood loss remain the primary causes of early trauma-related mortality. One-quarter to one-third of trauma patients exhibit trauma-induced coagulopathy (TIC). Thromboelastometry (ROTEM) and thrombelastography (TEG) are valuable alternatives to standard coagulation testing, providing a more comprehensive overview of the coagulation process. Purpose: Evaluating thromboelastographic profile, the incidence of fibrinolysis (defined as Ly30 > 3%) in severe trauma patients, and factors influencing pathological coagulation pattern. Methods: Prospective observational 2\ua0years cohort study on severe trauma patients assisted by Helicopter Emergency Medical System (HEMS) and Level 1 Trauma Center, in a tertiary referral University Hospital. Results: Eighty three patients were enrolled, mean NISS (new injury severity score) 36 (\ub1 13). Mean R value decreased from 7.25 (\ub1 2.6) to 6.19 (\ub1 2.5) min (p 40 groups, changes in R value increased their significance (p = 0.04 and p < 0.03, respectively). Pathological TEG was found in 71 (88.8%) patients at T0 and 74 (92.5%) at T1. Hypercoagulation was present in 57 (71.3%) patients at T0, and in 66(82.5%) at T1. 9 (11.3%) patients had hyperfibrinolysis at T0, 7 (8.8%) patients at T1. Prevalence of StO2 < 75% at T0 was greater in patients whose TEG worsened (7 patients, 46.7%) against whose TEG remained stable or improved (8 patients, 17.4%) from T0 to T1 (p = 0.02). 48 (57.8%) patients received < 1000\ua0mL of fluids, while 35 (42.2%) received 65 1000\ua0mL. The first group had fewer patients with hypercoagulation (20, 41.6%) than the second (6, 17.6%) at T1 (p < 0.03). No differences were found for same TEG pattern at T0, nor other TEG pattern. Conclusion: Our population is representative of a non-hemorrhagic severe injury subgroup. Almost all of our trauma population had coagulation abnormalities immediately after the trauma; pro-coagulant changes were the most represented regardless of the severity of injury. NISS appears to affect only R parameter on TEG. Hyperfibrinolysis has been found in a low percentage of patients. Hypoperfusion parameters do not help to identify patients with ongoing coagulation impairment. Small volume resuscitation and mild hypotermia does not affect coagulation, at least in the early post-traumatic phase

Thoracic ultrasound evaluation and B-type natriuretic peptide value in elective cesarean section under spinal anesthesia

Pregnancy-induced changes in cardiovascular status make women more susceptible to pulmonary edema. During cesarean section, to counterbalance the effect of hypotension caused by spinal anesthesia, anesthesiologists must choose between two fundamental approaches to maintain the hemodynamic state-intravenous fluids or vasopressors-and this choice will depend upon their particular opinions and experience. We aim to assess for any correlations between thoracic ultrasound A- and B-line artifacts, brain natriuretic peptide (BNP) levels, and the amount of intraoperative fluids administered

Direct photolysis of benzoylecgonine under UV irradiation at 254nm in a continuous flow microcapillary array photoreactor

Benzoylecgonine (BE) is the major metabolite of cocaine and a contaminant of emerging concern often detected in sewage treatment plant (STP) effluents and surface waters. In this study, an innovative microcapillary film (MCF) array photoreactor made of fluoropolymer material was used to determine the direct photolysis quantum yield of benzoylecgonine at 254 nm. The quantum yield of BE was found to be (6.22 ± 0.19) × 10-3 mol ein-1. The proposed methodology was validated by estimating the quantum yield of caffeine (7.48 10-4 ± 0.64) × 10-4 mol ein-1, which was found in agreement with results published in literature. The MCF uses a very small sample volume (in the order of 330μl per meter length of material) and allows extremely rapid photolysis with a short contact time ranging from a fraction of seconds to a few minutes. This new microfluidics approach presented in this study is particularly useful for determining the photochemical behavior of highly priced pharmaceuticals, illicit drugs, metabolites and uncommon or regulated substances