Repozitorij Univerze v Novi Gorici

Iskanje po repozitoriju
A+ | A- | Pomoč | SLO | ENG

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


61 - 70 / 73
Na začetekNa prejšnjo stran12345678Na naslednjo stranNa konec
61.
62.
Determination of Dissolved Iron Redox Species in Freshwater Sediment using DGT Technique Coupled to BDS
Yue Gao, Arne Bratkič, Dorota Korte, Aleksander Kravos, Hanna Budasheva, Mladen Franko, 2019, izvirni znanstveni članek

Opis: In this work we have developed a novel method for determination of iron redox species by the use of diffusive gradients in thin-film (DGT) technique coupled to photothermal beam deflection spectroscopy (BDS). The combination of both methods achieved low limit of detection (LOD) of 0.14 μM for Fe (II) ions. The total Fe concentration determined in the Vrtojbica river sediment (Slovenia, Rožna Dolina, 5000 Nova Gorica) was 49.3 μgL–1. The Fe (II) and Fe (III) concentra- tion amounted to 12.8 μgL–1 and 39.9 μgL–1, respectively. Such an approach opens new opportunities for monitoring the content of iron species in natural waters and sediments and provides highly sensitive chemical analysis and an accurate qualitative and quantitative characteristic of the materials under study.
Najdeno v: osebi
Ključne besede: Beam deflection spectroscopy, diffusive gradients in thin-film technique, iron redox species, photothermal techniques, sediment
Objavljeno: 26.02.2019; Ogledov: 2344; Prenosov: 86
.pdf Polno besedilo (452,58 KB)

63.
64.
65.
66.
67.
68.
Towards a novel method for iron species determination in Antarctic sea ice
Hanna Budasheva, Arne Bratkič, Dorota Korte, Mladen Franko, 2021, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Sea-ice borne iron has been found to be an important factor controlling Southern Ocean phytoplankton growth [1]. Knowing the amount and chemical speciation of its labile fraction in sea ice would advance our understanding of the involved processes. Unfortunately, it is rather difficult to perform their measurement because of limited access to the Antarctic. Thus there is a strong need for the development of a quick, simple and reliable technique for determination of iron and its speciation in sea-ice that ensures also low enough limits of detection. Recently, diffusive gradients in thin films (DGT) have been widely used as passive samplers for collecting time-averaged data on the concentrations of transition metals in different media [2]. DGTs are further coupled to an analytical technique that in case of detecting metals in passive sampler films primarily requires their extraction [3], which may potentially lead to changes of the metal specification. In the present study, the beam deflection spectrometry (BDS) is coupled to DGT and used to determine the average concentration of iron in the sea ice samples collected at the Davis Station in the Antarctic. Such a combined technique has been already successfully applied for detecting labile iron species in freshwater sediments [4]. The obtained BDS data were validated by thermal lens spectrometry (TLS) and UV-Vis spectrophotometry (SPEC). The distribution of iron species over a given ice surface area using the DGT-BDS technique revealed total iron concentrations in the range of 0.6 – 5.3 μgL-1, whereas the Fe2+ content was found to be in the range of 0.1 – 1.5 μgL-1. The range taking into account all of the measurement points (5×4), the precision of a single measured point is 0.2 μgL-1. The calculated 24 h-average concentration of total Fe labile species in the ice by using BDS is 2.3 ± 0.5 μgL-1, which coincides with data obtained by SPEC (2.5 ± 0.4 μgL-1) and TLS (2.39 ± 0.02 μgL-1). Our results indicate that it is possible to develop a robust, contamination-resilient detection method for measuring the labile iron species concentration in the sea ice. In opposite to TLS and SPEC, BDS-DGT provides reliable information not only about the speciation of iron but also about their distribution on the ice surface.
Najdeno v: osebi
Ključne besede: beam deflection spectrometry, diffusive gradients, thin films, iron species, photothermal techniques, Antarctic sea ice
Objavljeno: 30.11.2021; Ogledov: 527; Prenosov: 0
.pdf Polno besedilo (216,61 KB)
Gradivo ima več datotek! Več...

69.
Through-plane and in-plane thermal diffusivity determination of graphene nanoplatelets by photothermal beam deflection spectrometry
Stefano Bellucci, Hanna Budasheva, Behnaz Abbasgholi N. Asbaghi, Humberto Cabrera, Dorota Korte, 2021, izvirni znanstveni članek

Opis: In this work, in-plane and through-plane thermal diffusivities and conductivities of a freestanding sheet of graphene nanoplatelets are determined using photothermal beam deflection spectrometry. Two experimental methods were employed in order to observe the effect of load pressures on the thermal diffusivity and conductivity of the materials. The in-plane thermal diffusivity was determined by the use of a slope method supported by a new theoretical model, whereas the through-plane thermal diffusivity was determined by a frequency scan method in which the obtained data were processed with a specifically developed least-squares data processing algorithm. On the basis of the determined values, the in-plane and through-plane thermal conductivities and their dependences on the values of thermal diffusivity were found. The results show a significant difference in the character of thermal parameter dependence between the two methods. In the case of the in-plane configuration of the experimental setup, the thermal conductivity decreases with the increase in thermal diffusivity, whereas with the through-plane variant, the thermal conductivity increases with an increase in thermal diffusivity for the whole range of the loading pressure used. This behavior is due to the dependence of heat propagation on changes introduced in the graphene nano-platelets structure by compression.
Najdeno v: osebi
Ključne besede: graphene nanoplatelets, thermal diffusivity, thermal conductivity, photothermal spectrometry
Objavljeno: 30.11.2021; Ogledov: 464; Prenosov: 17
URL Polno besedilo (0,00 KB)
Gradivo ima več datotek! Več...

70.
Application of beam deflection spectrometry for the determination of iron species in passive samplers exposed to Southern Ocean ice
Hanna Budasheva, Arne Bratkič, Martin Šala, Dorota Korte, Mladen Franko, 2021, prispevek na konferenci brez natisa

Najdeno v: osebi
Objavljeno: 02.12.2021; Ogledov: 455; Prenosov: 1
.pdf Polno besedilo (1,52 MB)
Gradivo ima več datotek! Več...

Iskanje izvedeno v 0 sek.
Na vrh