Naphthalene Detection in Air by Highly Sensitive TiO2 Sensor: Real Time Response to Concentration Changes Monitored by Simultaneous UV Spectrophotometry.

Volatile low-weight polycyclic aromatic hydrocarbons (PAHs) are known to be potentially toxic to humans and animals. Their detection in ambient air has been of great interest in recent years and various detection methods have been implemented. In this study, we used naphthalene as a basic model of such compounds and constructed our own version of a titanium oxide-based sensor system for its detection. The main goal of the study was to clearly demonstrate the effectiveness of this type of sensor, record its response under well-controlled conditions, and compare that response to concentration measurements made by the widely accepted spectrophotometric method. With that goal in mind, we recorded the sensor response while monitoring naphthalene vapor concentrations down to 95 nM as measured by spectrophotometry. Air flow over the sensor was passed continuously and sample measurements were made every 3 min for a period of up to 2 h. Over that period, several cycles of naphthalene contamination and cleaning were implemented and measurements were recorded. The relative humidity and temperature of the air being sampled were also monitored to assure no major variations occurred that could affect the measurements. The sensor showed high sensitivity and a reproducible response pattern to changes in naphthalene concentration. It could be easily "cleaned" of the compound in ten minutes by means of the application of UV light and the passing of fresh air. Pending testing with other volatile PAH, this type of sensor proves to be an effective and inexpensive way to detect naphthalene in air.

Outcomes of acute kidney injury in a nephrology ward.

Acute kidney injury (AKI) is a global problem which predicts immediate and long-term adverse outcomes. We evaluated the AKI progression to end-stage renal disease, as well as the mortality associated with AKI and the in-hospital readmission rate because of a cardiovascular event in AKI patients admitted in a nephrology ward. A 5-year retrospective study was set in a nephrology department, with a follow-up period of up to 8 years. In a total of 191 patients, mean age was 73.83 ± 12.49 years, and 137 (71.7%) patients had history of chronic kidney disease. One hundred and twenty-four (65%) patients needed RRT and two (1%) needed surgery. Upon discharge, 107 (56%) patients had recovered the renal function, 41 (21.6%) patients had partial recovery, 25 (13%) patients were RRT dependent, 16 (8.4%) died, and two (1%) patients had outcomes unknown to us, because they were transferred to other hospitals. The median survival time free of RRT was 74 months. The median survival time of the followed patients was 34 months (95% CI 23.3-44.7). The mortality rate in the follow-up period in this sample was 18 deaths/100 patients-years, and the incidence of a composite cardiovascular endpoint of heart failure, acute coronary syndrome, and stroke was 6 events/100 patients-years. The mortality rate in the follow-up period was higher than usually described for patients outside intensive care unit, probably because our patients were old and had many comorbidities.

A sensitive crude oil bioassay indicates that oil spills potentially induce a change of major nitrifying prokaryotes from the archaea to the bacteria.

The sensitivity of nitrifiers to crude oil released by the BP Deepwater Horizon oil spill in Gulf of Mexico was examined using characterized ammonia-oxidizing bacteria and archaea to develop a bioassay and to gain further insight into the ecological response of these two groups of microorganisms to marine oil spills. Inhibition of nitrite production was observed among all the tested ammonia-oxidizing organisms at 100 ppb crude oil. Nitrosopumilus maritimus, a cultured representative of the abundant Marine Group I Archaea, showed 20% inhibition at 1 ppb, a much greater degree of sensitivity to petroleum than the tested ammonia-oxidizing and heterotrophic bacteria. The differing susceptibility may have ecological significance since a shift to bacterial dominance in response to an oil spill could potentially persist and alter trophic interactions influenced by availability of different nitrogen species.

A screening technique useful for testing the effectiveness of novel "self-cleaning" photocatalytic surfaces.

We describe a screening methodology that can be used to quickly determine the effectiveness of newly synthesized photocatalysts. We were particularly interested in measuring the destruction of organic molecules painted onto a photocatalytic surface by spraying, with destruction proceeding in ambient air (as a model for airborne toxin destruction). Our method can utilize photocatalysts that are synthesized as powders (such as doped and undoped titanium oxide) and which are then calcined onto a glass substrate disk at 600°C. Herein, we used UV illumination of Aeroxide P-25 TiO(2), but the method is general and can accommodate any region of the light spectrum.