Search results for "leaching"

Surface versus bulk composition of a phosphate glass

1994

Transmission and conversion electron Mossbauer spectroscopy as well as photoelectron spectroscopy were applied to study alterations of the surface layer of an iron containing industrial phosphate glass as compared with its bulk. In the surface layer, after polishing and exposure to ambient atmosphere, Fe 2+ is partially oxidized to Fe 3+ . This oxidation, however, does not increase the O/P ratio in this layer, because it goes along with a strong leaching of network modifiers. This leaching leads to a net decrease of the O/P ratio because it overcompensates the relative oxygen increase by Fe 2+ oxidation and by uptake of water

Effects of Dissolved Complexation on REE Fate During Interactions between Volcanic Ash and Coexisting Fluids

2013

AbstractThis work analyzes REE behavior during the delivery of volcanic ash into a marine system and highlights the effects induced by dissolved carbonate and humate complexes on REE release. Kinetic experiments were carried out during a 6-month period using a batch method approach. Results show that the highest degree of REE leaching occurs during the early stage. Altered phases that crystallize induce REE sorption and dissolved complexation towards surface complexation, concurrent processes that are enhanced by Y/Ho, La/Yb, and Ce/Ce* changes, whereas dissolved humates and carbonates influence the dissolution rate of ash and the dissolved REE behavior.

TRACE ELEMENT BEHAVIOUR IN SEAWATER DURING PYROCLASTIC ETNA'S ACTIVITY IN 2001. CONCURRENT EFFECTS OF NUTRIENTS AND FORMATION OF ALTERATION MINERALS

2010

From July 13 2001 began the most intense Etna's eruptive activity in the last 300 years. While this phenomenon occurred the oceanographic cruise ANSIC 01 was carrying out. Therefore the unique opportunity is arisen to investigate the chemical effects on marine system of delivery of large amount of pyroclastic particles (about 1 g m-2) into seawater. Comparing collected trace element data with those analysed during the oceanographic cruise JUVENILE 99, carried out two years before, large enrichments in V, Cr, Mn, Fe, Co, Cu and Pb contents have been recognised and attributed to leaching of freshly-erupted volcanic ash. Further comparison between to-day and previous collected trace element da…

Rate of clay mineral, poorly cristalline and crystalline oxy-hydroxide formation and humus development in volcanic soils of Etna (Sicily).

2006

Influence of soil surface sealing and hydrophobicity on water infiltration

Nella tesi viene affrontato lo studio dell’impatto dei fenomeni di sealing superficiale e di idrofobicità sui processi di infiltrazione dell’acqua nel suolo. A tal fine vengono utilizzati diversi tipi di esperimenti infiltrometrici che consentono di determinare le modificazioni delle proprietà idrauliche del suolo indotte da questi due fenomeni permettendo di valutare così le loro ripercussioni negative sui processi idrologici. The thesis aims at investigating the effects of soil sealing and hydrophobicity on the water infiltration process. Different field infiltrometric techniques are applied at this end due to their ability to characterize modifications of soil hydraulic properties that d…

Evaluation of the effect of different enamel surface treatments and waiting times on the staining prevention after bleaching

2017

Background Bleached dental enamel can be more susceptible to staining than the enamel that has never been bleached, especially right after tooth bleaching. The aim of this study is to evaluate the effect of surface treatments and waiting time prior to contact with dye on bleached enamel staining susceptibility. Material and Methods One hundred teeth were bleached with 35% hydrogen peroxide (Whiteness HP, FGM) and randomly assigned to G1 artificial saliva, G2 2% sodium fluoride (Flugel, Nova DFL), G3 casein phosphopeptide-amorphous calcium phosphate fluoride paste (CPP-ACPF, MI Paste Plus, GC America), G4 rinse for color maintenance after bleaching (Keep White Rinse, DMC) and G5 polishing wi…

The comparative research of leaching tests and the sequential chemical extraction based on the environmental risk assessment by a selected type of wa…

2020

The problem of the circulation of metal ions in the environment remains a current problem in view of the quality of received agricultural crops. The necessity of increasingly frequent use of alternative sources of biogenesis in the form of waste substances poses a threat of bringing significant amounts of heavy metals harmful to human health and life to soils. The article discusses a significant problem, which is the comparison of the results of the environmental impact assessment of waste obtained based on the implementation of legitimate leaching tests (the three-stage leachability test according to PN-Z-15009) with the results obtained from sequential chemical extraction tests according …

Compost Effect on Diuron Retention and Transport in Structured Vineyard Soils

2015

12 pages; International audience; Diuron is frequently detected in surface- and groundwater under the vineyards, where organic amendments are often used, in Burgundy of France. Undisturbed column experiments were conducted to study the influence of three composted organic amendments on diuron leaching through columns of two vineyard soils from Vosne-Romanée (VR, calcareous Cambisol) and Beaujolais (Bj, sandy Leptosol), France. Bromide (used as non-reactive tracer) and diuron breakthrough curves (BTCs) were analyzed using convectivedispersive equation (CDE), two-region (mobile-immobile, MIM) and two-site models. No influence of the composts was observed on the bromide recovery rates. The CDE…

Different Behaviour of Plasma Antioxidant Status after Red Wine Consumption in Subjects of the Same Sex: A Preliminary Report

2012

<p>Several studies report that the plasma antioxidant capacity (PAC) increases after a single ingestion of red wine. However, data on the different behaviour of PAC after food intake in subjects of the same sex are still lacking. On the basis of these observations some investigations were undertaken in order to evaluate the effects of red wine intake on PAC in a homogeneous groups of healthy female volunteers (n=18). Additionally, the possible correlation between increase of PAC values and increase in uric acid levels was also assessed. PAC and uric acid concentrations were determined before wine intake and 50, 120 and 240 minutes thereafter. The results obtained following these studi…

Polar Localization of a Tripartite Complex of the Two-Component System DcuS/DcuR and the Transporter DctA in Escherichia coli Depends on the Sensor K…

2014

The C4-dicarboxylate responsive sensor kinase DcuS of the DcuS/DcuR two-component system of E. coli is membrane-bound and reveals a polar localization. DcuS uses the C4-dicarboxylate transporter DctA as a co-regulator forming DctA/DcuS sensor units. Here it is shown by fluorescence microscopy with fusion proteins that DcuS has a dynamic and preferential polar localization, even at very low expression levels. Single assemblies of DcuS had high mobility in fast time lapse acquisitions, and fast recovery in FRAP experiments, excluding polar accumulation due to aggregation. DctA and DcuR fused to derivatives of the YFP protein are dispersed in the membrane or in the cytosol, respectively, when …