174 research outputs found
Документи Державного архіву Чернігівської області як джерело захисту прав жертв нацистського окупаційного режиму
The retention of phosphorus in surface waters through co-precipitation of
phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich
groundwater is not well understood. We developed an experimental field
set-up to study Fe(II) oxidation and P immobilization along the flow-path
from groundwater into surface water in an agricultural experimental
catchment of a small lowland river. We physically separated tube drain
effluent from groundwater discharge before it entered a ditch in an
agricultural field. Through continuous discharge measurements and weekly
water quality sampling of groundwater, tube drain water, exfiltrated
groundwater, and surface water, we investigated Fe(II) oxidation kinetics
and P immobilization processes. The oxidation rate inferred from our field
measurements closely agreed with the general rate law for abiotic oxidation
of Fe(II) by O<sub>2</sub>. Seasonal changes in climatic conditions affected the
Fe(II) oxidation process. Lower pH and lower temperatures in winter
(compared to summer) resulted in low Fe oxidation rates. After exfiltration
to the surface water, it took a couple of days to more than a week before
complete oxidation of Fe(II) is reached. In summer time, Fe oxidation rates
were much higher. The Fe concentrations in the exfiltrated groundwater were
low, indicating that dissolved Fe(II) is completely oxidized prior to inflow
into a ditch. While the Fe oxidation rates reduce drastically from summer to
winter, P concentrations remained high in the groundwater and an order of
magnitude lower in the surface water throughout the year. This study shows
very fast immobilization of dissolved P during the initial stage of the
Fe(II) oxidation process which results in P-depleted water before Fe(II) is
completely depleted. This cannot be explained by surface complexation of
phosphate to freshly formed Fe-oxyhydroxides but indicates the formation of
Fe(III)-phosphate precipitates. The formation of Fe(III)-phosphates at redox
gradients seems an important geochemical mechanism in the transformation of
dissolved phosphate to structural phosphate and, therefore, a major control
on the P retention in natural waters that drain anaerobic aquifers
Het effect van faunapassages bij rijkswegen op de levensvatbaarheid van dierpopulaties; potentiële onderzoeklocaties
Тренинговые услуги в украинском туризме: состояние, тенденции, проблемы
Целью данной статьи является анализ места и роли тренингов в системе туризма Украины на фоне общемировых тенденций
Het toevoegen van kopersulfaat aan rantsoenen voor mestvarkens = Effect of adding copper sulphate to rations for fattening pigs
Current Tolerance-Associated Peripheral Blood Gene Expression Profiles After Liver Transplantation Are Influenced by Immunosuppressive Drugs and Prior Cytomegalovirus Infection
Spontaneous operational tolerance to the allograft develops in a proportion of liver transplant (LTx) recipients weaned off immunosuppressive drugs (IS). Several previous studies have investigated whether peripheral blood gene expression profiles could identify operational tolerance in LTx recipients. However, the reported gene expression profiles differed greatly amongst studies, which could be caused by inadequate matching of clinical parameters of study groups. Therefore, the purpose of this study was to validate differentially expressed immune system related genes described in previous studies that identified tolerant LTx recipients after IS weaning. Blood was collected of tolerant LTx recipients (TOL), a control group of LTx recipients with regular IS regimen (CTRL), a group of LTx recipients with minimal IS regimen (MIN) and healthy controls (HC), and groups were matched on age, sex, primary disease, time after LTx, and cytomegalovirus serostatus after LTx. Quantitative Polymerase Chain Reaction was used to determine expression of twenty selected genes and transcript variants in PBMCs. Several genes were differentially expressed between TOL and CTRL groups, but none of the selected genes were differentially expressed between HC and TOL. Principal component analysis revealed an IS drug dosage effect on the expression profile of these genes. These data suggest that use of IS profoundly affects gene expression in peripheral blood, and that these genes are not associated with operational tolerance. In addition, expression levels of SLAMF7 and NKG7 were affected by prior cytomegalovirus infection in LTx recipients. In conclusion, we found confounding effects of IS regimen and prior cytomegalovirus infection, on peripheral blood expression of several selected genes that were described as tolerance-associated genes by previous studies
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