The child's developing concept of inference

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN021346 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Διερεύνηση της βιολογικής και φυσικοχημικής αναγωγής του εξασθενούς χρωμίου με τη χρήση εδαφικών στηλών και πειραμάτων μικρόκοσμου.

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Επιστήμη και Τεχνολογία Υλικών

Reductive Cr(VI) Removal under Different Reducing and Electron Donor Conditions—A Soil Microcosm Study

Increased groundwater and soil contamination by hexavalent chromium have led to the employment of a variety of detoxification methods. Biological remediation of Cr(VI) polluted aquifers is an eco-friendly method that can be performed in situ by stimulating the indigenous microbial population with organic and inorganic electron donors. In order to study the effect of different redox conditions on microbial remediated Cr(VI) reduction to Cr(III), microcosm experiments were conducted under anaerobic, anoxic, and sulfate-reducing conditions and at hexavalent chromium groundwater concentrations in the 0–3000 μg/L range, with groundwater and soil collected from an industrial area (Inofyta region). As electron donors, molasses, emulsified vegetable oil (EVO), and FeSO4 were employed. To quantitatively describe the degradation kinetics of Cr(VI), pseudo-first-order kinetics were adopted. The results indicate that an anaerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III), while the addition of Fe2+ can further increase Cr(VI) removal rate significantly. Furthermore, Cr(VI) microbial reduction is possible in the presence of NO3− at rates comparable to anaerobic Cr(VI) microbial reduction, while high sulfate concentrations have a negative effect on Cr(VI) bioreduction rates in comparison to lower sulfate concentrations

Biotic and Abiotic Biostimulation for the Reduction of Hexavalent Chromium in Contaminated Aquifers

Hexavalent chromium is a carcinogenic heavy metal that needs to be removed effectively from polluted aquifers in order to protect public health and the environment. This work aims to evaluate the reduction of Cr(VI) to Cr(III) in a contaminated aquifer through the stimulation of indigenous microbial communities with the addition of reductive agents. Soil-column experiments were conducted in the absence of oxygen and at hexavalent chromium (Cr(VI)) groundwater concentrations in the 1000–2000 μg/L range. Two carbon sources (molasses and EVO) and one iron electron donor (FeSO4·7H2O) were used as ways to stimulate the metabolism and proliferation of Cr(VI) reducing bacteria in-situ. The obtained results indicate that microbial anaerobic respiration and electron transfer can be fundamental to alleviate polluted groundwater from hazardous Cr(VI). The addition of organic electron donors increased significantly Cr(VI) reduction rates in comparison to natural soil attenuation rates. Furthermore, a combination of organic carbon and iron electron donors led to a longer life span of the remediation process and thus increased total Cr(VI) removal. This is the first study to investigate biotic and abiotic Cr(VI) removal by conducting experiments with natural soil and by applying biostimulation to modify the natural existing microbial communities

Pravastatin versus Placebo in Pregnancies at High Risk of Term Preeclampsia.

BACKGROUND: Effective screening for term preeclampsia is provided by a combination of maternal factors with measurements of mean arterial pressure, serum placental growth factor and serum soluble fms-like tyrosine kinase-1 at 35 to 37 weeks of gestation, with detection rate of about 75%, at screen positive rate of 10%. However, there is no known intervention to reduce the incidence of the disease. METHODS: In this multicenter, double-blind, placebo-controlled trial, we randomly assigned 1,120 women with singleton pregnancies at high-risk of term preeclampsia to receive pravastatin, at a dose of 20 mg per day, or placebo from 35 to 37 weeks of gestation until delivery or 41 weeks. The primary outcome was delivery with preeclampsia at any time after randomization. The analysis was performed according to intention-to-treat. RESULTS: A total of 29 women withdrew consent during the trial. Preeclampsia occurred in 14.6% (80/548) participants in the pravastatin group and in 13.6% (74/543) in the placebo group. Allowing for the effect of risk at the time of screening and participating centre, the mixed effects Cox regression showed no evidence of an effect of pravastatin; hazard ratio (statin/placebo) 1.08 (95% confidence interval: 0.78, 1.49; p=0.65). There was no evidence of interaction between the effect of pravastatin, estimated risk of preeclampsia, previous pregnancy history, adherence and aspirin treatment. There was no significant between-group difference in the incidence of any secondary outcomes, including gestational hypertension, stillbirth, abruption, delivery of small for gestational age neonates, neonatal death or neonatal morbidity. There was no significant between-group difference in the treatment effects on serum placental growth factor and soluble fms-like tyrosine kinase-1 concentrations 1 and 3 weeks after randomization Adherence was good, with reported intake of 80% or more of the required number of tablets in 89% of participants. There were no significant between-group differences in neonatal adverse outcomes or other adverse events.pre-print263 K