Comparative effect of simulated solar light, UV, UV/H2O2 and photo-Fenton treatment (UV-Vis/H2O2/Fe2+,3+) in the Escherichia coli inactivation in artificial seawater.

Innovative disinfection technologies are being studied for seawater, seeking a viable alternative to chlorination. This study proposes the use of H2O2/UV254 and photo-Fenton as disinfection treatment in seawater. The irradiations were carried out using a sunlight simulator (Suntest) and a cylindrical UV reactor. The efficiency of the treatment was compared for Milli-Q water, Leman Lake water and artificial seawater. The presence of bicarbonates and organic matter was investigated in order to evaluate possible effects on the photo-Fenton disinfection treatment. The photo-Fenton treatment, employing 1 mg L(-1) Fe(2+) and 10 mg L(-1) of H2O2, led to the fastest bacterial inactivation kinetics. Using H2O2/UV254 high disinfection rates were obtained similar to those obtained with photo-Fenton under UV254 light. In Milli-Q water, the rate of inactivation for Escherichia coli was higher than in Leman Lake water and seawater due to the lack of inorganic ions affecting negatively bacteria inactivation. The presence of bicarbonate showed scavenging of the OH(•) radicals generated in the treatment of photo-Fenton and H2O2/UV254. Despite the negative effect of inorganic ions, especially HCO3(-), the disinfection treatments with AOPs in lake water and seawater improved significantly the disinfection compared to light alone (simulated sunlight and UV254). In the treatment of photo-Fenton with simulated sunlight, dissolved organic matter had a beneficial effect by increasing the rate of inactivation. This is associated with the formation of Fe(3+)-organo photosensitive complexes leading to the formation of ROS able to inactivate bacteria. This effect was not observed in the photo-Fenton with UV254. Growth of E. coli surviving in seawater was observed 24 and 48 h after treatment with UV light. However, growth of surviving bacteria was not detected after photo-Fenton with UV254 and H2O2/UV254 treatments. This study suggests H2O2/UV254 and photo-Fenton treatments for the disinfection of seawater, in spite its high concentration of salts.

Traumatic neuroma of extrahepatic bile ducts after orthotopic liver transplantation.

Traumatic neuromas (TN) of the biliary tree causing strictures have only occasionally been described after liver transplantation. Herein, we have reported 15 cases of TN that were detected between 1 and 17 months after transplantation (median: 4 months) during surgery for obstructive jaundice (12 cases), after alterations of liver function tests (two cases), or incidentally discovered after retransplantation (n = 1) we resected the lesion and the biliary anastomosis. Pathological examination and immunostaining for S-100 protein were performed to study the nerve fascicles. After a median follow-up time of 64 months (range = 0-127), 10 patients are alive without any complication related to the previous biliary TN. We propose the following classification: type I: TN originating from and located in the main biliary tract wall, and type II: TN arising from the surrounding tissues next to the main biliary tract. We conclude that TN are not uncommon after liver transplantation and that they are sometimes symptomatic, causing a biliary stricture that requires surgical treatment. We propose a classification to help patient selection for surgery. In our opinion, resection of the TN is the operation of choice, together with resection of the involved biliary tract in type I TN.

Portable pilot plant for evaluating marine biofouling growth and control in heat exchangers-condensers.

Biofouling frequently involves a serious impediment to achieving optimum operating conditions in heat exchangers-condensers. The economic coat and energy losses associated with this phenomenon are significant and the environmental impact of biocides must satisfy stringent regulations. A portable pilot plant has been designed in order to carry out in-situ experimental study as biofilm is formed under thermal and hydrodynamically controlled conditions. The pilot plant has an automatic monitoring, control and data acquisition system, which automatically processes data from indirect measure of fouling in terms of increased fluid frictional and heat transfer resistances. A particular method is used and proposed for direct measuring and biofilm characterization. Once we know the actual film thickness, we can calculate the effective thermal conductivity of the layer by using the appropriate heat transfer equations.

Solvent effects on oxygen-17 chemical shifts in methyl formate: linear solvation shift relationships.

A multiple linear regression analysis has been carried out using the Kamlet-Abboud-Taft solvatochromic parameters in order to quantify the solvent effects on the (17)O chemical shifts of methyl formate (MF). The influence of the solvents upon the carbonyl oxygen chemical shifts is smaller for MF than for N-methylformamide (NMF). The influence (in parts per million) of the solvent polarity-polarizability reduces from -21.9pi* in amides to -9.6pi* in MF. The influence of the solvent hydrogen-bond-donor acidities reduces from -42.0alpha in formamides to -16.9alpha in MF. The solvent effects upon the dicoordinated oxygen chemical shifts of MF are smaller in magnitude and opposite in direction, i.e., 4.8pi* and 2.6alpha, than those for the carbonyl oxygen. (17)O hydration shifts have been calculated for the NMF + (H(2)O)(6) and MF + (H(2)O)(5) complexes by the ab initio GIAO method at the 6-311 + G** level. The hydration shifts calculated for the carbonyl oxygens of NMF and MF and for the dicoordinated oxygen of MF, -102.4, -64.7, and 17.6 ppm, respectively, show the same trend as the corresponding empirical hydration shifts, -101.7, -42.0, and 14.2 ppm.

[Renal effects of prolonged sevoflurane anesthesia in Wistar rats]. / Efectos renales de la anestesia prolongada con sevoflurano en ratas Wistar.

OBJECTIVES: To assess renal safety of sevoflurane administered to Wistar rats at clinical concentrations during prolonged periods of inhalation. MATERIAL AND METHODS: The experimental animals were assigned to two groups of six rats each. Group I received anesthesia with 1.5% sevoflurane for 6 hours and group II received the same concentration of sevoflurane for 15 hours. The anesthesia was inhaled in an open circuit of fresh air at 1 l/min (medicinal air, 22.75% O2). The animals were kept in metabolic cages throughout the nine days the experiment lasted. Weight and urine output were recorded daily and the day before anesthesia was started, inorganic fluoride and blood was analyzed for renal function (urea, sodium, and blood urea nitrogen [BUN]). Between two and three hours after withdrawal of anesthesia, inorganic fluoride was again assessed, and on the last day of the experiment a new blood sample was taken to evaluate renal function. Kidney tissue was then studied. RESULTS: The two groups were similar as to weight, urea, sodium and BUN. Hourly diuresis was significantly greater after anesthesia in group II but not in group I. Inorganic fluoride was significantly higher in both groups, with postanesthetic levels of 22.42 +/- 1.76 microM/l in group I and 35.05 +/- 1.80 microM/l in group II. Renal tissue from both groups appeared normal under an optical microscope. CONCLUSIONS: Sevoflurane at the doses tested increases inorganic fluoride concentrations although for both periods the levels stayed under 50 microM/l, which has been considered the nephrotoxic threshold. No signs of changes in renal function were observed in blood texts or tissue studies.