1. Pursuing the stabilisation of crystalline nanostructured magnetic manganites through a green low temperature hydrothermal synthesisPaolo Dolcet, Arianna Minelli, Stefano Diodati, Sandra Gardonio, Claudia Innocenti, Denis Badocco, Stefano Gialanella, Paolo Pastore, Luciano Pandolfo, Andrea Caneschi, Angela Trapanati, Silvia Gross, 2017, izvirni znanstveni članek Opis: A quick, easy and green water-based synthesis protocol involving coprecipitation of oxalates combined with hydrothermal treatment resulted in the crystallisation of nanostructured manganites at a relatively low temperature (180 °C). The subcritical hydrothermal approach was shown to play a key role in stabilising phases which are generally achieved at much higher temperatures and under harsher conditions, thus disclosing an exciting alternative for their synthesis. Through this mild wet chemistry approach, the compounds CuMnO2, ZnMn2O4 and ZnMnO3 were synthesised as nanocrystalline powders. Noticeably, the optimised route proved to be effective in stabilising the exotic polymorph cubic spinel ZnMnO3 in pure form. This is particularly notable, as very few records concerning this compound are available in the literature. The compounds were fully characterised from compositional, structural, morphological and magnetic points of view.
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Povzetek najdenega: ...for their synthesis. Through this mild wet chemistry approach, the compounds CuMnO2, ZnMn2O4 and ZnMnO3...
Ključne besede: nanostructured manganites, low temperature wet chemistry synthesis
Objavljeno: 28.03.2017; Ogledov: 3592; Prenosov: 0
 Polno besedilo (1,59 MB) |
2. CityFlux perfluorocarbon tracer experimentsFredrik K Petersson, Damien Martin, Iain R White, Stephen J Henshaw, Graham Nickless, Ian Longley, Carl J Percival, Martin Gallagher, Dudley E. Shallcross, 2010, izvirni znanstveni članek Opis: In June 2006, two perfluorocarbon tracer experiments were conducted in central Manchester UK as part of the CityFlux campaign. The main aim was to investigate vertical dispersion in an urban area during convective conditions, but dispersion mechanisms within the street network were also studied. Paired receptors were used in most cases where one receptor was located at ground level and one at roof level. One receptor was located on the roof of Portland Tower which is an 80m high building in central Manchester. Source receptor distances in the two experiments varied between 120 and 600 m. The results reveal that maximum concentration was sometimes found at roof level rather than at ground level implying the effectiveness of convective forces on dispersion. The degree of vertical dispersion was found to be dependent on source receptor distance as well as on building height in proximity to the release site. Evidence of flow channelling in a street canyon was also found. Both a Gaussian profile and a street network model were applied and the results show that the urban topography may lead to highly effective flow channelling which therefore may be a very important dispersion mechanism should the right meteorological conditions prevail. The experimental results from this campaign have also been compared with a simple urban dispersion model that was developed during the DAPPLE framework and show good agreement with this. The results presented here are some of the first published regarding vertical dispersion. More tracer experiments are needed in order to further characterise vertical concentration profiles and their dependence on, for instance, atmospheric stability. The impact of urban topography on pollutant dispersion is important to focus on in future tracer experiments in order to improve performance of models as well as for our understanding of the relationship between air quality and public health.
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Povzetek najdenega: ...air quality, atmospheric chemistry, concentration (composition), convective system, dispersion, public health,...
Ključne besede: air quality, atmospheric chemistry, concentration (composition), convective system, dispersion, public health, street canyon, tracer, urban area
Objavljeno: 18.07.2019; Ogledov: 2224; Prenosov: 0
Polno besedilo (1,07 MB) |
3. What effect does VOC sampling time have on derived OH reactivity?Hannah Sonderfeld, Iain R White, Iain C A Goodall, James R Hopkins, Alistair C Lewis, Ralf Koppmann, Paul S Monks, 2016, izvirni znanstveni članek Opis: State-of-the-art techniques allow for rapid measurements of total OH reactivity. Unknown sinks of OH and oxidation processes in the atmosphere have been attributed to what has been termed ĝ€missingĝ€ OH reactivity. Often overlooked are the differences in timescales over which the diverse measurement techniques operate. Volatile organic compounds (VOCs) acting as sinks of OH are often measured by gas chromatography (GC) methods which provide low-frequency measurements on a timescale of hours, while sampling times are generally only a few minutes. Here, the effect of the sampling time and thus the contribution of unmeasured VOC variability on OH reactivity is investigated. Measurements of VOC mixing ratios by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) conducted during two field campaigns (ClearfLo and PARADE) in an urban and a semi-rural environment were used to calculate OH reactivity. VOCs were selected to represent variability for different compound classes. Data were averaged over different time intervals to simulate lower time resolutions and were then compared to the mean hourly OH reactivity. The results show deviations in the range of 1 to 25%. The observed impact of VOC variability is found to be greater for the semi-rural site.The selected compounds were scaled by the contribution of their compound class to the total OH reactivity from VOCs based on concurrent gas chromatography measurements conducted during the ClearfLo campaign. Prior to being scaled, the variable signal of aromatic compounds results in larger deviations in OH reactivity for short sampling intervals compared to oxygenated VOCs (OVOCs). However, once scaled with their lower share during the ClearfLo campaign, this effect was reduced. No seasonal effect on the OH reactivity distribution across different VOCs was observed at the urban site.
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Povzetek najdenega: ...Hydroxyl radical, Atmospheric chemistry, Box model...
Ključne besede: Hydroxyl radical, Atmospheric chemistry, Box model
Objavljeno: 18.07.2019; Ogledov: 2069; Prenosov: 0 |
4. Variations in U concentrations and isotope signatures in two Canadian lakes impacted by U mining: A combination of anthropogenic and biogeochemical processesWei Wang, Duc Huy Dang, Breda Novotnik, R. Douglas Evans, Thai T. Phan, 2019, izvirni znanstveni članek Opis: Temporal and vertical variations in uranium (U) concentrations and U isotope (δ238U, ‰) signatures were
examined in sediment cores collected seven times over a one year period, from two lakes in Ontario, Canada,
which are contaminated with U by historical mining activities. Bow Lake is holomictic, experiencing seasonal
anoxia, while the sediments of meromictic Bentley Lake are permanently anoxic. Average annual peak concentrations
of U in Bow Lake subsurface sediments were approximately 300 μg L−1 and 600 μg g−1 in porewater
and bulk sediments, respectively. Similar ranges of concentrations (900 μg L−1 and 600 μg g−1, respectively)
were observed in Bentley Lake sediments. The exceedingly high levels of U observed in the porewaters of both
lakes, as well as the seasonal variability in U levels, challenge the traditional paradigm regarding U chemistry,
i.e., that reduced U(IV) should be insoluble under anoxic conditions.
The average annual δ238U ‰ values at the sediment-water interface of both lakes were similar (i.e.,
0.47 ± 0.09‰ and 0.50 ± 0.16‰, relative to IRMM-184). The deep sediments in both Bentley Lake and Bow
Lake record U isotope composition with a typical fractionation of 0.6‰ relative to the surface water, confirming
authigenic U accumulation, i.e., negligible contribution of particulate material from the tailings. Also, the δ238U
values in porewater have an average offset of ca. −0.1‰ relative to bulk sediments in anoxic zones and are
reversed in the oxic sediment layer.
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Povzetek najdenega: ...levels, challenge the traditional paradigm regarding U chemistry,
i.e., that reduced U(IV) should be insoluble under...
Ključne besede: Uranium
Isotope composition
Uranium tailings
Biogeochemical cycling
Redox chemistry
Objavljeno: 09.10.2019; Ogledov: 2279; Prenosov: 0
Polno besedilo (3,89 MB) |
5. Symmetry2009, druga izvedena dela Najdeno v: ključnih besedah
Povzetek najdenega: ...physics, chemistry, biology, mathematics, computer science, engineering...
Ključne besede: physics, chemistry, biology, mathematics, computer science, engineering
Objavljeno: 28.10.2019; Ogledov: 1905; Prenosov: 13
Polno besedilo (864,82 KB)
Gradivo ima več datotek! Več...
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6. Microwave-assisted synthesis of a viologen-based covalent organic polymer with redox-tunable polarity for dye adsorptionAli Trabolsi, John-Carl Olsen, Selbi Nuryyeva, Thirumurugan Prakasam, Tina Škorjanc, Gobinda Das, 2017, izvirni znanstveni članek Najdeno v: ključnih besedah
Ključne besede: viologen, microwave synthesis, phosphazene, dye adsorption, redox chemistry
Objavljeno: 02.09.2020; Ogledov: 1691; Prenosov: 0
Polno besedilo (2,48 MB) |
7. Immobilization of redox-responsive switches into calixarene-based covalent organic polymers for environmental applicationsAli Trabolsi, Ramesh Jagannathan, Sudhir Kumar Sharma, Dinesh Shetty, Tina Škorjanc, 2017, prispevek na konferenci brez natisa Najdeno v: ključnih besedah
Povzetek najdenega: ...calixarene, covalent polymers, redox chemistry, chemical switches...
Ključne besede: calixarene, covalent polymers, redox chemistry, chemical switches
Objavljeno: 03.09.2020; Ogledov: 1603; Prenosov: 0
Polno besedilo (373,43 KB) |
8. Redox-Tunable Polycationic Polymers for Environmental ApplicationsTina Skorjanc, Goinda Das, Selbi Nuryyeva, Thirumurugan Prakasam, Ali Trabolsi, 2017, objavljeni povzetek znanstvenega prispevka na konferenci Najdeno v: ključnih besedah
Povzetek najdenega: ...covalent polymers, viologen, redox chemistry, pollutant removal, dye adsorption, iodine capture...
Ključne besede: covalent polymers, viologen, redox chemistry, pollutant removal, dye adsorption, iodine capture
Objavljeno: 10.09.2020; Ogledov: 1654; Prenosov: 0
Gradivo ima več datotek! Več...
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9. Introduction of a Redox-Responsive Switch into calix[4]arene-based Covalent Organic Nanosheets for Environmental ApplicationsTina Skorjanc, 2018, objavljeni povzetek znanstvenega prispevka na konferenci Najdeno v: ključnih besedah
Povzetek najdenega: ...redox chemistry, viologen, covalent organic polymers, calixarene, dye adsorption,...
Ključne besede: redox chemistry, viologen, covalent organic polymers, calixarene, dye adsorption, iodine adsorption
Objavljeno: 11.09.2020; Ogledov: 1671; Prenosov: 0
Polno besedilo (2,11 MB) |
10. The microbial diversity of a storm cloud as assessed by hailstonesNiels Woetmann Nilesen, Bjarne Munk Hansen, Kai Finster, Tina Šantl Temkiv, Ulrich Gosewinkel Karlson, 2012, izvirni znanstveni članek Najdeno v: ključnih besedah
Povzetek najdenega: ...bacterial diversity, species richness, species evenness, atmospheric chemistry, biogeography...
Ključne besede: cloud-borne bacteria, bacterial diversity, species richness, species evenness, atmospheric chemistry, biogeography
Objavljeno: 04.01.2021; Ogledov: 1620; Prenosov: 0
Polno besedilo (194,35 KB) |
