Low radiation dose computed tomography coronary angiography: evaluation of the variations in coronary arteries.

OBJECTIVE: Despite attempts to decrease the radiation dose, coronary computed tomography angiography (CCTA) generally uses higher doses than computed tomography scans of other organs. The purpose of this study was to evaluate the incidence of the variations of the coronary arteries using the adaptive statistical iterative reconstruction technique to perform low-dose coronary computed tomography (CTA). METHODS: Diagnostic CCTA scans were performed in 3433 patients (from November 2010 to January 2015) using an Optima CT660 (GE Healthcare, USA) 64-slice and analyzed retrospectively. RESULTS: The mean effective dose was 2.1 mSv (1.2-4.9 mSv) for prospective and 4.5 mSv (3.6-9.1 mSv) for retrospective ECG-gated scans. The variations of the coronary arteries (CA) excluding myocardial bridge (MB) were detected in 76 (2.2 %) of the 3433 patients. A myocardial bridge was the most common variation (n = 288, 8.3 %). The second most common variation (n = 13, 17.1 %) was an absence of the left main coronary artery (LMCA) with separate starting points for the left anterior descending (LAD) and left circumflex (LCX) arteries. In addition, there was a rare variation (n = 1, 1.3 %) consisting of the LAD artery originating from the right coronary artery (RCA). CONCLUSIONS: The present retrospective study was conducted using CCTA on patients with a coronary artery variations in Turkey (n = 3433). Our data show that low-dose CCTA can be used to detect common coronary variations.

Bio-reduction of tetrachloroethen using a H2-based membrane biofilm reactor and community fingerprinting.

Chlorinated ethenes in drinking water could be reductively dechlorinated to non-toxic ethene by using a hydrogen based membrane biofilm reactor (H2-MBfR) under denitrifying conditions as it provides an appropriate environment for dechlorinating bacteria in biofilm communities. This study evaluates the reductive dechlorination of perchloroethene (PCE) to non-toxic ethene (ETH) and comparative community analysis of the biofilm grown on the gas permeable membrane fibers. For these purposes, three H2-MBfRs receiving three different chlorinated ethenes (PCE, TCE and DCE) were operated under different hydraulic retention times (HRTs) and H2 pressures. Among these reactors, the H2-MBfR fed with PCE (H2-MBfR 1) accomplished a complete dechlorination, whereas cis-DCE accumulated in the TCE receiving H2-MBfR 2 and no dechlorination was detected in the DCE receiving H2-MBfR 3. The results showed that 95% of PCE dechlorinated to ETH together with over 99.8% dechlorination efficiency. Nitrate was the preferred electron acceptor as the most of electrons generated from H2 oxidation used for denitrification and dechlorination started under nitrate deficient conditions at increased H2 pressures. PCR-DGGE analysis showed that Dehalococcoides were present in autotrophic biofilm community dechlorinating PCE to ethene, and RDase genes analysis revealed that pceA, tceA, bvcA and vcrA, responsible for complete dechlorination step, were available in Dehalococcoides strains.

Stripping/flocculation/membrane bioreactor/reverse osmosis treatment of municipal landfill leachate.

This study presents a configuration for the complete treatment of landfill leachate with high organic and ammonium concentrations. Ammonia stripping is performed to overcome the ammonia toxicity to aerobic microorganisms. By coagulation-flocculation process, COD and suspended solids (SS) were removed 36 and 46%, respectively. After pretreatment, an aerobic/anoxic membrane bioreactor (Aer/An MBR) accomplished the COD and total inorganic nitrogen (total-N(i)) removals above 90 and 92%, respectively, at SRT of 30 days. Concentrations of COD and total-N(i) (not considering organic nitrogen) in the Aer/An MBR effluent decreased to 450 and 40 mg/l, respectively, by significant organic oxidation and nitrification/denitrification processes. As an advanced treatment for the leachate, the reverse osmosis (RO) was applied to the collected Aer/An MBR effluents. Reverse osmosis provided high quality effluent by reducing the effluent COD from MBR to less than 4.0mg/l at SRT of 30 days.