Anaerobic biodegradation of methyl tert-butyl ether under iron-reducing conditions in batch and continuous-flow cultures.

The feasibility of biodegradation of the fuel oxygenate methyl tert-butyl ether (MTBE) under iron-reducing conditions was explored in batch and continuous-flow systems. A porous pot completely-mixed reactor was seeded with diverse cultures and operated under iron-reducing conditions. For batch studies, culture from the reactor was transferred anaerobically to serum bottles containing either MTBE alone or MTBE with ethanol (EtOH) and excess electron acceptor. In the continuous-flow reactor, MTBE conversion to tert-butyl alcohol (TBA) was observed after 181 days of operation, and stable removal was achieved throughout the remainder of the study. Simultaneously, both the MTBE only and the MTBE and EtOH iron-reducing batch serum bottles also began to degrade MTBE. Bottles were respiked and the degradation rate was determined to be 2.36 +/- 0.10 x 10(-4) mmol MTBE/min-kgVSS. The EtOH present with MTBE degraded faster (7.76 +/- 0.08 x 10(-3) mmol EtOH/min-kg VSS) but did not have a noticeable effect on the rate of MTBE degradation. No evidence of TBA degradation was observed by the iron-reducing cultures. Stoichiometry of iron utilization was determined from the iron balance of the continuous-flow reactor, and it was found that the bulk of the electron acceptor was required for energy and maintenance with little remaining for cell synthesis. This is consistent with a yield coefficient of less than 0.1. Molecular analysis of the iron-reducing culture by denaturing gradient gel electrophoresis indicated that uncultured strains of delta-Proteobacteria were dominant in the reactor.     

Prenatal diagnosis of Pierre–Robin sequence as part of Stickler syndrome

Stickler syndrome or hereditary progressive arthro-ophthalmopathy, is an autosomal dominant condition characterized by ocular manifestations, arthritic changes, orofacial features and deafness, in variable degrees. We report the first case of prenatal diagnosis of Stickler syndrome in a child with a Pierre–Robin sequence (PRS) causing a polyhydramnios. When isolated polyhydramnios is not explained by immunological, metabolic or infectious causes, swallowing difficulty due to PRS must be considered. As PRS is aetiologically heterogenous, the prognosis depends on the cause. Genetic investigations and familial history must be taken into account. Here, in a context of familial Stickler syndrome, making the prenatal diagnosis of PRS as part of Stickler syndrome allowed us to reassure the parents and to anticipate airway trouble at the child's birth. Copyright © 2002 John Wiley & Sons, Ltd.     

Prenatal exclusion of homocystinuria (cystathionine β-synthase deficiency) by assay of phytohaemagglutinin-stimulated fetal lymphocytes

Homocystinuria due to cystathionine β-synthase deficiency was excluded in a fetus at 23 weeks' gestation by demonstrating activity of the enzyme in fetal lymphocytes after stimulation by phytohaemagglutinin. Fetal blood sampling was carried out because two determinations of enzyme activity on cultured amniotic cells gave low, not fully diagnostic values.     

Maintaining a neutral water balance in a 450 MWe NGCC-CCS power system with post-combustion carbon dioxide capture aimed at offshore operation

A post-combustion CO₂ capture process intended for offshore operations has been designed and optimised for integration with a natural gas-fired power plant on board a floating structure developed by the Norway-based company Sevan Marine ASA—designated Sevan GTW (gas-to-wire). The concept is constrained by the structure of the floater carrying a SIEMENS modular power system rated at 450 MW_e, with a capture rate of 90% and CO₂ compression (1.47 Mtpa) for pipeline pressure at 12 MPa. A net efficiency of 45% (based on a lower heating value) is estimated for the system with CO₂ capture, thus suggesting that the post-combustion CO₂ capture system is accountable for a fuel penalty of nine percentage points.The rationale behind the technology selection is the urgency of replacing the dispersed aero-derivative gas turbines which power the offshore oil and gas production units in Norwegian waters with near-zero emission power.As (inherently) fresh water usually constitutes a limiting factor in sea operations, efforts are made to obtain a neutral water balance to obtain an optimal design. This is primarily achieved by controlling the cleaned flue gas temperature at the top of the absorber column.     

Associations between CB-153 and p,p'-DDE and hormone levels in serum in middle-aged and elderly men

BACKGROUND: Animal and epidemiologic data indicate that exposure to persistent organochlorine pollutants (POPs) may disrupt the hypothalamus-pituitary-thyroid (HPT) and the hypothalamus-pituitary-gonadal (HPG) axes. We have assessed whether the POP-biomarkers 2,2'4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis(4-chlorophenyl)-ethene (p,p'-DDE) affect thyrotropin (TSH), thyroid hormones, gonadotropins or sex hormone concentrations in men. METHODS: Lipid adjusted serum concentrations of CB-153, and p,p'-DDE, were determined in 196 men (median age 59 years, range 48-82). Hormone analyses in serum were performed with immunoassays. The effect of CB-153 and p,p'-DDE (as continuous or categorized variables) were evaluated by linear regression models, adjusting for potential confounders. RESULTS: There was a significant positive association between p,p'-DDE and TSH. An increase of 100 ng/g lipid of p,p'-DDE corresponded to an increase of 0.03 mU/l (95% Confidence Interval (CI) 0.01, 0.05) in TSH level. The explanatory value (R(2)) of the multivariate model was only 7%. Moreover, there was a significant negative association between p,p'-DDE and estradiol. An increase of 100 ng/g lipid of p,p'-DDE corresponded to a decrease of 0.57 pmol/l (95% CI -1.0, -0.12) in estradiol level. The R(2)-value was only 4%. No associations were observed between any of the POP biomarkers and the other hormones. CONCLUSIONS: The positive association between p,p'-DDE and TSH and the negative association between p,p'-DDE and estradiol, among middle-aged and elderly men, were not accompanied by associations between the POP-markers and thyroxin, testosterone, and gonadotropins, respectively. The results gives some additional support for that POP exposure may affect HPT- and HPG-axes also in humans, but the overall epidemiological data are still not coherent enough to allow any firm conclusions.     

Evaluation of fluoranthene phytotoxicity in pea plants by Hill reaction and chlorophyll fluorescence

The effect of both increased concentrations (0.01 and 1 mg l(-1)) of fluoranthene (FLT) and the duration of exposure (18 and 25 days) on the growth and photosynthetic processes in pea plants (Pisum sativum L., cv. Garde) was investigated. FLT concentration in roots and shoot of pea plants was also determined. The obtained results demonstrated that the higher concentration of FLT (1 mg l(-1)) significantly inhibited the growth of the pea plants after 25 days of the application, also affected the content of photosynthetic pigments (chlorophyll a, b and carotenoids), and the primary photochemical processes of photosynthesis. In chlorophyll fluorescence parameters, the significant increase of F(0) values and the decrease of F(V)/F(M) and Phi(II) values was recorded. The Hill reaction of isolated chloroplasts of pea plants was significantly inhibited after 25 days by presence of FLT (0.01 and 1 mg l(-1)) in nutrient solution, while after 18 days no significant response of Hill reaction activity was recorded. The fluoranthene content in roots and shoot of pea plants increased with increasing FLT concentration in the environment and the substantial accumulation of FLT was observed in the roots.     

Role of plant activity and contaminant speciation in aquatic plant assimilation of 2,4,5-trichlorophenol

Aquatic plants uptake, transform and sequester organic contaminants and are used as a bioremediation strategy for the removal of pollutants from wastewaters. A better understanding of factors affecting rate of uptake of contaminants by aquatic plants is needed to improve engineered systems for removal of pollutants from wastewaters. This work focused on delineating sorption to plant surfaces and understanding effects of plant metabolic activity, inhibition, and media pH on the uptake of the ionizable contaminant 2,4,5-trichlorophenol (TCP) by aquatic plant Lemna minor. During L. minor exposure to TCP (0.5-13.9 mg l(-1)), a range of plant metabolic activities was measured using oxygen production rate (0-18.4 micromol h(-1)). A positive correlation was shown between contaminant uptake rate and plant activity. Contaminant uptake was examined at a range of media pH values (6-9) and uptake rates were linearly correlated to fraction of contaminant in protonated form. These results demonstrated a link between plant activity and uptake of contaminant by plants and stress the importance of incorporating plant metabolic activity and contaminant speciation in development of natural and engineered phytoremediation systems. This research also indicates that aquatic plants can actively accumulate trace-organic contaminants and may ultimately serve as a sink for these materials in the natural environment.     

Essential host plant cues in the grapevine moth

Host plant odours attract gravid insect females for oviposition. The identification of these plant volatile compounds is essential for our understanding of plant–insect relationships and contributes to plant breeding for improved resistance against insects. Chemical analysis of grape headspace and subsequent behavioural studies in the wind tunnel show that host finding in grapevine moth Lobesia botrana is encoded by a ratio-specific blend of three ubiquitous plant volatiles. The odour signal that attracts mated females to grape consists of the terpenoids (E)-β-caryophyllene, (E)-β-farnesene and (E)-4,8-dimethyl-1,3,7-nonatriene. These compounds represent only a fraction of the volatiles released by grapes, and they are widespread compounds known throughout the plant kingdom. Specificity may be achieved by the blend ratio, which was 100:78:9 in grape headspace. This blend elicited anemotactic behaviour in moths at remarkably small amounts. Females were attracted at release rates of only a few nanograms per minute, at levels nearly as low as those known for the attraction of male moths to the female sex pheromones.