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Household and road dust as indicators of airborne particulate matter elemental composition
Klemen Teran, 2020, doktorska disertacija

Opis: Household dust (HD) and road dust (RD) are widespread and easily accessible urban sediments, which are influenced by deposition of airborne particulate matter (PM). Since airborne PM is considered to be one of the most important pollutants in urban areas, with significant adverse effects on human health, a better understanding of its elemental composition and dispersion mechanisms is needed. The present study examines whether the HD and RD elemental composition can be used as a quick alternative method for the determination of corresponding PM elemental composition over a selected area. In summer 2016, HD, RD, and topsoil samples were collected from 249 sampling locations distributed across rural, urban, and industrial areas in Slovenia. The collected samples were sieved for particle diameters below 63 μm and analysed for 53 elements with ICP-MS after aqua regia digestion. SEM/EDS analyses were applied for the determination of characteristic particles at the microlevel. Finally, the elemental composition of HD and RD was compared with the PM10 elemental composition obtained from National Network for Ambient Air Quality Monitoring governed by Slovenian Environmental Agency (ARSO) to determine any potential connection between them. The results show that HD and RD are considerably enriched with a large set of elements compared to the topsoil. Correlations and factor analyses show that spatial distribution of factor scores in RD revealed strong regional trends, connected with soil resuspension (Al, Ce, Ga, K, La, Li, P, Rb, Sc and Y) or with anthropogenic sources such as traffic (Ag, Bi, Cu, Sb and Sn), steel mill emissions (Cr, Mo, Mn, Ni and W) and construction material decomposition (Ca and Sr). In contrast, HD elemental composition was highly variable between sampling locations. Variability was probably caused by indoor sources, such as smoking (Ce and La), biomass combustion (K, P and Rb), construction material decomposition (Ca and Sr) and residents’ professional occupation: dental care employees (Ag, Au, Pd) and employees in the metal-processing industry (Cr, Mo, Ni). Among deposited particles in RD, urbanization processes, such as fossil fuel combustion and traffic emissions, including brake pad abrasion and tyre wear, contributed the largest share of particles with anomalous elemental composition. Brake pad abrasion, for instance, contributed Ba-, Cu-, Sn-, and Zn-enriched irregular, angular and tabular particles, while tyre wear produced elongated rubber particles with traces of Ba, Cu, and Zn. RD from urban areas showed significantly higher elemental levels of Ag, Bi, Ca, Cd, Cr, Cu, Hg, Fe, Mo, Nb, Pb, Pt, Sb, Sn, Sr, Ti, Zn, and W in comparison to the rural environment, indicating the strong impact of urbanization on RD elemental composition. Another important anthropogenic source of deposited particles in RD were steel mills. Strong anomalies of Cr, Mo and Ni were detected in their vicinity. Their elemental levels decreased with distancing from the plan location, reaching urban background levels between 15 and 20 km from the mills. SEM/EDS analyses identified enrichments of Cr, Mn, Mo, Ni, V, and W in spherical particles and particles with partially melted surfaces, which were found only in the proximity of steel mills, indicating their influence of the PM deposition. Comparison of RD and the corresponding PM10 elemental composition showed that the RD fraction with particle diameters below 63 μm reflects PM10 elemental composition for the last 30 to 90 days for Cr, Cu, Mo and Zn and can be used as a predictor for PM10 elemental levels. This is not true for HD, as indoor particle sources prevail over the deposition of ambient PM10.
Najdeno v: ključnih besedah
Povzetek najdenega: ...traffic (Ag, Bi, Cu, Sb and Sn), steel mill emissions (Cr, Mo, Mn, Ni and...
Ključne besede: household dust, road dust, particulate matter, PM10, pollution, Slovenia, steel mills, topsoil, traffic, urbanization
Objavljeno: 02.12.2020; Ogledov: 1744; Prenosov: 91
.pdf Polno besedilo (16,34 MB)

Modeling of occurrence of surface defects of C45 steel with genetic programming
Miha Kovačič, Robert Jager, 2015, izvirni znanstveni članek

Najdeno v: ključnih besedah
Ključne besede: mechanical engineering, metallurgy, C45 steel, making steel
Objavljeno: 17.05.2016; Ogledov: 2586; Prenosov: 122
URL Polno besedilo (0,00 KB)

A meshless model of electromagnetic braking for the continuous casting of steel
Božidar Šarler, Robert Vertnik, Katarina Mramor, 2015, izvirni znanstveni članek

Najdeno v: ključnih besedah
Ključne besede: continuous casting of steel, turbulent flow, magnetic field, macro-segregation
Objavljeno: 17.05.2016; Ogledov: 3377; Prenosov: 115
URL Polno besedilo (0,00 KB)

Polyphenol, antioxidant and antimicrobial potential of six different white and red wine grape processing leftovers
Peter Raspor, Sonja Smole Možina, Katja Jug, Melita Sternad Lemut, Branka Mozetič Vodopivec, Anja Klančnik, Kajetan Trošt, 2016, izvirni znanstveni članek

Opis: BACKGROUND During winemaking, grape polyphenols are only partly extracted, and consequently unexploited. The main aim was to characterise the phenolic content of freeze-dried grape skin and seed (FDSS) extracts obtained from Slovenian and international grape varieties and evaluate their antioxidant, antimicrobial, and anti-adhesive activities. RESULTS FDSS of six Vitis vinifera L. grapevine cultivars from Vipava Valley region (Slovenia) underwent extraction and sonification under different conditions. Flavonols were the predominant content of extracts from white ‘Zelen’ and ‘Sauvignon Blanc’ grape varieties, with strong antimicrobial activities against Gram-negative bacteria. ‘Pinot Noir’ FDSS extracted with 50% aqueous ethanol extraction produced a high phenolic content in the final extract, which was further associated with strong antioxidant and antimicrobial activities against all tested bacteria. Bacterial adhesion to stainless steel surfaces with minimal and maximal surface roughness was significantly inhibited (up to 60%) across a wide FDSS concentration range, with lower concentrations also effective with two types of stainless steel surfaces. CONCLUSION FDSS extracts from winery by-products show interesting phenolic profiles that include flavonols, catechins, anthocyanins, and hydroxycinnamic acids, with yields influenced by grapevine cultivar and extraction conditions. The antioxidant, antimicrobial and anti-adhesive activities of 50% aqueous ethanol ‘Pinot Noir’ FDSS extract reveals potential applications in food, pharmaceutical and cosmetic industries for these bioactive residues.
Najdeno v: ključnih besedah
Povzetek najdenega: ...all tested bacteria. Bacterial adhesion to stainless steel surfaces with minimal and maximal surface roughness...
Ključne besede: grape skins and seeds, extraction solvents, phenolic profile, antioxidant activity, antimicrobial activity, anti-adhesion activity to stainless steel
Objavljeno: 08.08.2016; Ogledov: 3795; Prenosov: 0
.pdf Polno besedilo (2,02 MB)

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