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Povzetek: Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation efficiency after longer periods has not been reported. To gain insights into the mechanisms of immobilization of cadmium (Cd), lead (Pb), and znic (Zn), a study was performed in the laboratory experiment in uncontaminated, artificially contaminated, and remediated soils, and these soils treated with sulfate, to mimic conditions in contaminated soil from zinc smelter site. Remediation was performed by mixing contaminated soil with paper-ash to immobilize Cd, Pb, and Zn in the geotechnical composite. Partitioning of Cd, Pb, and Zn was studied over one year in seven-time intervals applying the sequential extraction procedure and complementary X-ray diffraction analyses. This methodological approach enabled us to follow the redistribution of Cd, Pb, and Zn over time, thus, to studying immobilization mechanisms and assessing the remediation efficiency and stability of newly formed mineral phases. Cd, Pb, and Zn were effectively immobilized by precipitation of insoluble hydroxides after the addition of paper-ash and by the carbonization process in insoluble carbonate minerals. After remediation, Cd, Pb, and Zn concentrations in the water-soluble fraction were well below the limiting values for inertness: Cd by 100 times, Pb by 125 times, and Zn by 10 times. Sulfate treatment did not influence the remediation efficiency. Experimental data confirmed the high remediation efficiency and stability of insoluble Cd, Pb, and Zn mineral phases in geotechnical composites.
Ključne besede: cadmium, lead, zinc, contaminated soil, paper ash, immobilization mechanisms
Objavljeno v DiRROS: 04.07.2023; Ogledov: 356; Prenosov: 233
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Povzetek: This paper investigates the effectiveness of a specific crystalline waterproofing admixture (CWA) in concrete as a function of a water–binder ratio. Four concrete mixes with and without CWA were prepared; two of them with a water–binder ratio of 0.45 and two of them with a water– binder ratio of 0.55. Water permeability and compressive strength were tested on hardened concrete specimens and self-healing of cracks over time was observed. Cement paste and CWA paste were prepared to clarify the results obtained on the concrete specimens. SEM and EDS and XRD and FTIR were performed on the hardened pastes to explain the mechanism of CWA working. The results show that the addition of CWA had no significant effect on the compressive strength of the concrete, but reduced the water penetration depth in the concrete, and the reduction was more effective for mixes with lower water–binder ratio. Regarding the self-healing effect, it can be concluded that the addition of CWA improves the crack healing in concrete, but the efficiency of self-healing is highly dependent on the initial crack width. The mechanisms involved in the reduction of water penetration depth and crack healing in concrete can be explained by different mechanisms; one is creation of the CSH gel from unreacted clinker grains, then formation carbonate, and additional mechanism is gel formation (highly expansive Mg-rich hydro-carbonate) from magnesium based additives. The presence of sodium silicate, which would transform into carbonate/bicarbonate, also cannot be excluded.
Ključne besede: slag, self healing concrete, crystal admixture, microstructural analysis
Objavljeno v DiRROS: 03.07.2023; Ogledov: 284; Prenosov: 203
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Objavljeno v DiRROS: 20.06.2023; Ogledov: 333; Prenosov: 137
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Povzetek: Obsevanje je del standardnega zdravljenja bolnic z rakom dojk. Odgovor na zdravljenje z obsevanjem je pri vsakem posamezniku drugačen in je odvisen tudi od genetskih dejavnikov. Eden od novejših genetskih označevalcev odgovora na obsevanje je dolžina telomerov. Telomeri ščitijo kromosome pred krajšanjem in vzdržujejo genomsko stabilnost. Rezultati naše raziskave kažejo, da se dinamika spreminjanja dolžine telomerov takoj po zdravljenju z obsevanjem in v šestih mesecih po obsevanju pri bolnicah z neinvazivnim rakom dojk spreminja in bi lahko služila kot biološki označevalec odgovora na obsevanje. Molekularni mehanizmi, povezani s tem procesom, ostajajo zaenkrat večinoma neraziskani.
Ključne besede: rak dojk, obsevanje, onkološko zdravljenje
Objavljeno v DiRROS: 16.06.2023; Ogledov: 355; Prenosov: 140
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Ključne besede: varstvo gozdov, morfološke analize, rdeči bor, osip borovih iglic, Lophodermium seditiosum, siva plesen, Botrytis cinerea, sušica najmlajših borovih poganjkov, Diplodia pinea, ekološke razmere, vlažnost zraka
Objavljeno v DiRROS: 06.06.2023; Ogledov: 346; Prenosov: 75
Celotno besedilo (1,12 MB)