Synergistic effect of acetic acid and NOXfor objects made of lead and its alloys; Indoor corrosive environments in museums and depositories

Complex corrosion simulation to evaluate synergistic effect have to cover large number of factors. To do so, environmental and corrosion datasets collected by monitoring sites of interest have been used to tailor complex artificial ageing of lead and lead alloys, using lead, tin and tin-lead coupons. Material composition was based on objects of interest which are tin-lead alloy based although naming lead objects is used widespread for vast of them. To evaluate results corrosion rate based on weight loss, phase composition of corrosion product and colour change of the coupon surface were utilized. For thin corrosion layers formed micro Raman and FTIR did not provide suitable results, and GIXRD have been used. Although limited number of conditions were used for the simulations, synergistic effect was observed for lead under specific conditions. Synergistic effect do occur on lead when exposed to NOX and acetic acid fumes of relatively low concentrations (18 μg·m-3 and 500 ppb respectively). In addition, there is grouping of colourimetric data collected according to test regimes-phase composition of corrosion product respectively. This information albeit preliminary suggests that colourimetric spectroscopy may be suitable as fast and easy corrosion monitoring

Influence of linseed oil on the microstructure and composition of lime and lime-metakaolin pastes after a long curing time

This study investigates the effect of linseed oil on the microstructure of lime and lime-metakaolin pastes after 68 months of curing under controlled conditions. The hydrophobicity imparted by linseed oil to the pastes’ bulk was confirmed by measuring water drops’ contact angle. The results of thermal analysis, X-ray powder diffraction, and Fourier transform infrared spectroscopy showed that linseed oil significantly hindered the carbonation reaction in both lime and lime-metakaolin pastes and promoted the development of amorphous phases. The obtained results also indicated that linseed oil could foster the pozzolanic reaction in the lime-metakaolin system by stabilizing and/or promoting the development of hydration products resulting in reduced shrinkage in comparison with the reference

Leeches as Sensor-bioindicators of River Contamination by PCBs

The aim of the study was to evaluate the use of leeches of the genus Erpobdella as a means of assessing polychlorinated biphenyl contamination of watercourses. The River Skalice, heavily contaminated with PCBs, was selected as a model. The source of contamination was a road gravel processing factory in Rožmitál pod Třemšínem from which an estimated 1 metric ton of PCBs leaked in 1986. Levels of PCB were measured in leeches collected between 1992 to 2003 from 11 sites covering about 50 km of the river (the first sampling site upstream to the source of contamination and 10 sites downstream). The PCB indicator congeners IUPA no. 28, 52, 101, 118, 138, 153, and 180 were measured. Levels were highest at the four sampling sites nearest the source of pollution. The highest values of PCB congeners were found in 1992. PCB content decreased from 1992 to 2003 and with distance from the source. The study indicated that leeches of the genus Erpobdella are a suitable bioindicator of contamination in the surface layer of river sediments

Protective role of female gender in programmed accelerated renal aging in the rat

The aging kidney exhibits a progressive decline in glomerular filtration rate, accompanied by inflammatory and oxidative damage. We hypothesized that accelerated, age-related progression of renal injury is ovarian hormones-dependant. To address this we used an established model of developmentally programmed accelerated renal aging in the rat, superimposed by ovariectomy to assess interactions between ovarian hormones and the aging process. Under our experimental conditions, we found that kidney function worsens with age, that is GFR reduces over 18 month analyzed time-course and this was worsened by fetal exposure to maternal low-protein diet and absence of estrogen. Reduction in GFR was followed by increases in albuminuria, proteinuria, inflammatory markers, and tissue carbonyls, all suggesting inflammatory response and oxidative stress. This was associated with changes in AGTR2 expression which was greater at 18 months of age compared to earlier time points, but in MLP offspring only. Our studies show an influence of ovarian hormones on programmed accelerated renal aging and the AGTR2 across the lifespan. The main findings are that ovariectomy is a risk factor for increased aging-related renal injury and that this and oxidative damage might be related to changes in AGTR2 expression

Selective and quantitative nitrate electroreduction to ammonium using a porous copper electrode in an electrochemical flow cell

International audienceThe aim of this work was to set up a novel electrochemical system allowing an efficient transformation of concentrated nitrate solutions to ammonium and which can be subsequently implemented on a large scale application. First, this paper describes the preparation of a porous copper modified electrode by successive electrodeposition of nickel then copper on a graphite felt of large specific surface area. Homogeneous Cu coating of all fibers in the 3D porous structure was successfully obtained using low concentrations of copper salts and high applied current intensities. The porous copper electrode was then used in a flow electrochemical process to achieve a selective and quantitative transformation of concentrated nitrate into ammonium. Different electrolytic solutions, slightly acid (acetate buffer) or neutral (phosphate buffer), and flow rates were investigated. The nitrate solution was quantitatively reduced into NH4+ with high selectivity in only one pass through the electrode. When the applied current was similar to the theoretical one, the maximum selectivity (96%) and the best current efficiency (72%) for NH4+ formation were reached at pH 7.2 with a flow rate of 2 mL min−1. The obtained ammonium solution can be subsequently used either as a potential nitrogen source during microbial culture or simply as a fertilizer

Target screening of chemicals of concern in recycled water

The results of a characterisation study of water samples collected from an Advanced Water Recycling Plant (AWRP) operating in Perth, Western Australia are presented. The AWRP treats secondary wastewater by ultrafiltration, reverse osmosis (RO) and ultraviolet radiation (UV) to produce recycled water for groundwater replenishment. Water samples collected after RO and UV treatment were characterised by liquid chromatography-high resolution mass spectrometry, using an established protocol for target screening. The target screening of 291 compounds detected a total of 13 chemicals in post-RO and post-UV water, including 2 corrosion inhibitors (4+5-methyl-1H-benzotriazole, benzotriazole), 3 pesticides (metolachlor, propiconazol, prosulfocarb), 3 pharmaceuticals (lamotrigin, metformin, tramadol), 1 personal care product (galaxalidone), 3 artificial sweeteners (saccharin, acesulfame, sucralose) and 1 flame retardant (triethyl phosphate). The corrosion inhibitors benzotriazole and 4+5-methyl-1H-benzotriazole, and the pharmaceutical metformin were detected in hundreds of ng L−1, while the other compounds were present in low ng L−1 concentrations. Analysis of UV treated water samples showed that UV treatment also helped to reduced UV degradable compounds such as the corrosion inhibitors (>50% removal), triethyl phosphate (~50% removal) and the artificial sweetener acesulfame (~95% removal). Overall, the detection of 13 chemicals through target screening analyses did not account for the residual dissolved organic carbon (DOC) in post RO water, the majority of which is still an intriguing unknown. However, the target screening did show that there were no obvious “known” anthropogenic contaminants contributing to the majority of the DOC in post-RO and post-UV treated water. Calculated risk quotients (RQ) for all detected chemicals in UV treated water were 2 to 6 order of magnitude below 1, implying an high degree of safety associated with human consumption of recycled water. Overall the chemicals screening provided further evidence of the overall safety of the use of recycled wastewater treated by RO and UV as a potable water source

Ecotoxicity of carbamazepine and its UV photolysis transformation products

Carbamazepine, an anti-epileptic pharmaceutical agent commonly found in wastewater, is highly recalcitrant to standard wastewater treatment practices. This study investigated the mixture toxicity of carbamazepine transformation products formed during UV photolysis using three standard ecotoxicity assays (representing bacteria, algae and crustaceans). UV-treatment of 6 mg L-1 carbamazepine solution was carried out over a 120 min period and samples were removed periodically over the course of the experiment. Quantification results confirmed the degradation of carbamazepine throughout the treatment period, together with concurrent increases in acridine and acridone concentrations. Ecotoxicity was shown to increase in parallel with carbamazepine degradation indicating that the mixture of degradation products formed was more toxic than the parent compound. In fact, ecotoxicity was still greater than 60 % for all three endpoints even when the carbamazepine concentration had decreased to < 1 % of the starting concentration, and acridine and acridone had decreased to < 10 % of their maximum measured concentrations. Single compound toxicity testing also confirmed the higher toxicity of measured degradation products relative to the parent compound. These results show that transformation products considerably more toxic than carbamazepine itself are likely to be produced during UV treatment of wastewater effluents and/or photo-induced degradation of carbamazepine in natural waters. This study highlights the need to consider mixture toxicity and the formation and persistence of toxicologically relevant transformation products when assessing the environmental risks posed by pharmaceutical compounds

Impact of gonadectomy on blood pressure regulation in ageing male and female rats

Sexual dimorphism in blood pressure has been associated with differential expression of the angiotensin II (AII) receptors and with activity of the nervous system. It is generally accepted that aging affects kidney function as well as autonomic nervous system and hormonal balance. Given that hypertension is more prevalent in men than women until women reach their seventh decade we hypothesised that females would be relatively protected from adverse effects of ageing compared to males, and that this would be mediated by the protective effect of ovarian steroids. Intact and gonadectomised male and female normotensive Wistar rats aged 6, 12 and 18 months were used to study renal function, blood pressure, heart rate and blood pressure variability. We observed that intact females had lower levels of proteinuria and higher (12.5%) creatinine clearance compared to intact males, and that this difference was abolished by castration but not by ovariectomy. Ovariectomy resulted in a change by 9% in heart rate, resulting in similar cardiovascular parameters to those observed in males or gonadectomised males. Spectral analysis of systolic blood pressure revealed that high frequency power spectra were significantly elevated in the females vs. males and were reduced by ovariectomy. Taken altogether the results show that females are protected from age-related declining renal function and to a lesser extent from rising blood pressure in comparison to males. Whilst ovariectomy had some deleterious effects in females, the strongest effects were associated with gonadectomy in males, suggesting a damaging effect of male hormones

Polyamorphism and frustrated crystallization in the acid-base reaction of magnesium potassium phosphate cements

Magnesium potassium phosphate cements are a class of acid-base cements for bioengineering and civil engineering applications. The kinetics of their chemical reaction was investigated in situ with isothermal conduction calorimetry and powder X-ray diffraction, quantifying amorphous and crystalline products. The first reaction step, dissolution of MgO, with an apparent activation energy of 71 kJ mol-1, dictates the time evolution of two amorphous intermediate precursors and the crystalline product. The early crystallization of the latter has been described with an Avrami equation with an apparent activation energy of 81 kJ mol-1, pointing to a mechanism of deceleratory nucleation and growth in one direction, compatible with the acicular crystal habit observed with electron microscopy. The observed polyamorph transformation is controlled by a complex interplay between kinetic and thermodynamic factors, in which the changes in the chemical environment (increase in pH) driven by the MgO dissolution, play a crucial role. It is proposed that the onset of the amorphous-amorphous transformation hinders crystallization by decreasing ion mobility, raising the energy barriers to structural reorganization. The rate of MgO dissolution depends on the reactivity of the powder and the parameters of the mix (such as the amount of liquid) and influences the reaction pathways, impacting on material performance