Browsing by Subject "LIQUID"

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  • Katul, Gabriel; Mammarella, Ivan; Grönholm, Tiia; Vesala, Timo (2018)
    Two ideas regarding the structure of turbulence near a clear air-water interface are used to derive a waterside gas transfer velocity k(L) for sparingly and slightly soluble gases. The first is that k(L) is proportional to the turnover velocity described by the vertical velocity structure function D-ww(r), where r is separation distance between two points. The second is that the scalar exchange between the air-water interface and the waterside turbulence can be suitably described by a length scale proportional to the Batchelor scale l(B) = Sc-1/2, where Sc is the molecular Schmidt number and eta is the Kolmogorov microscale defining the smallest scale of turbulent eddies impacted by fluid viscosity. Using an approximate solution to the von Karman-Howarth equation predicting D-ww(r) in the inertial and viscous regimes, prior formulations for k(L) are recovered including (i) kL = root 2/15Sc(-1/2)v(K), v(K) is the Kolmogorov velocity defined by the Reynolds number v(K)eta/nu = 1 and nu is the kinematic viscosity of water; (ii) surface divergence formulations; (iii) k(L) alpha Sc(-1/2)u(*), where u(*) is the waterside friction velocity; (iv) k(L) alpha Sc-1/2 root g nu/u(*) for Keulegan numbers exceeding a threshold needed for long-wave generation, where the proportionality constant varies with wave age, g is the gravitational acceleration; and (v) k(L) = root 2/15Sc(-1/2) (nu g beta(o)q(o))(1/4) in free convection, where q(o) is the surface heat flux and beta(o) is the thermal expansion of water. The work demonstrates that the aforementioned k(L) formulations can be recovered from a single structure function model derived for locally homogeneous and isotropic turbulence.
  • Reischl, Bernhard; Raiteri, Paolo; Gale, Julian D.; Rohl, Andrew L. (2019)
    Advances in atomic force microscopy (AFM) in water have enabled the study of hydration layer structures on crystal surfaces, and in a recent study on dolomite (CaMg(CO3)(2)), chemical sensitivity was demonstrated by observing significant differences in force-distance curves over the calcium and magnesium ions in the surface. Here, we present atomistic molecular dynamics simulations of a hydration layer structure and dynamics on the (10 (1) over bar4) surfaces of dolomite, calcite (CaCO3), and magnesite (MgCO3), as well as simulations of AFM imaging on these three surfaces with a model silica tip. Our results confirm that it should be possible to distinguish between water molecules coordinating the calcium and magnesium ions in dolomite, and the details gleaned from the atomistic simulations enable us to clarify the underlying imaging mechanism in the AFM experiments.
  • Doulgeris, Konstantinos-Matthaios; Komppula, Mika; Romakkaniemi, Sami; Hyvarinen, Antti-Pekka; Kerminen, Veli-Matti; Brus, David (2020)
    Continuous, semi-long-term, ground-based in situ cloud measurements were conducted during the Pallas Cloud Experiment (PaCE) in 2013. The measurements were carried out in Finnish sub-Arctic region at Sammaltunturi station (67 degrees 58 ' N, 24 degrees 07 ' E; 560m a.s.l.), part of Pallas Atmosphere - Ecosystem Supersite and Global Atmosphere Watch (GAW) program. The main motivation of the campaign was to conduct in situ cloud measurements with three different cloud spectrometer probes and perform an evaluation of their ground-based setups. Therefore, we mutually compared the performance of the cloud and aerosol spectrometer (CAS), the cloud droplet probe (CDP) and the forward-scattering spectrometer probe (FSSP-100) (DMT; Boulder, CO, USA). We investigated how different meteorological parameters affect each instrument's ground-based setup operation and quantified possible biases and discrepancies of different microphysical cloud properties. Based on the obtained results we suggested limitations for further use of the instrument setups in campaigns where the focus is on investigating aerosol-cloud interactions. Measurements in this study were made by instruments owned by the Finnish Meteorological Institute and results concern their operation in sub-Arctic conditions with frequently occurring supercooled clouds. The measured parameter from each instrument was the size distribution, and additionally we derived the number concentration, the effective diameter, the median volume diameter and the liquid water content. A complete intercomparison between the CAS probe and the FSSP-100 ground setups and additionally between the FSSP-100 and the CDP probe ground setups was made and presented. Unfortunately, there was not a sufficient amount of common data to compare all three probes together due to operational problems of the CDP ground setup in sub-zero conditions. The CAS probe that was fixed to one direction lost a significant number of cloud droplets when the wind direction was out of wind iso-axial conditions in comparison with the FSSP-100 and the CDP, which were both placed on a rotating platform. We revealed that CAS and FSSP-100 had good agreement in deriving sizing parameters (effective diameter and median volume diameter from 5 to 35 mu m) even though CAS was losing a significant amount of cloud droplets. The most sensitive derived parameter was liquid water content, which was strongly connected to the wind direction and temperature.
  • Hamzah, Nurhazlina; Kjellberg, Matti; Vanninen, Paula (2021)
    Highly polar ethanolamines (EAs), excreted in urine, are hydrolysis products of nitrogen mustards (NMs), which are prohibited by the Chemical Weapons Convention (CWC). The methods established for biological matrices are essential for verification analysis of the CWC related chemicals. This paper describes a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method developed for qualitative and quantitative analysis of EAs, N-ethyldiethanolamine (EDEA), N-methyldiethanolamine (MDEA) and triethanolamine (TEAOH) from urine samples. After optimization of sample preparation and chromatographic conditions, the method was fully validated. Silica solid-phase extraction (SPE) cartridges and a porous graphite carbon (PGC) column were selected for validation studies. The method is linear from 5 to 500, 0.5 to 250, and 0.5 to 500 ng/mL for TEAOH, EDEA, and MDEA, respectively. It is also precise and accurate. A minimum sample amount of 0.5 mL urine was used. The limit of quantification using this approach was 0.4, 5.5, and 6.3 ng/mL for MDEA, EDEA and TEAOH, respectively. The combination of the PGC column and high pH eluents in analysis retained and separated the studied EAs. Retention times were 2.11, 2.56 and 2.98 min for MDEA, EDEA and TEAOH, respectively. The method is applicable for verification analysis of the CWC.
  • Avdibegović, Dženita; Zhang, Wenzhong; Xu, Junhua; Regadío, Mercedes; Koivula, Risto; Binnemans, Koen (2019)
    A continuous worldwide increase in scandium (Sc) criticality leads to a quest for secondary scandium resources. Among them, bauxite residue (BR) – a waste product from alumina refineries – often contains substantial amounts of scandium. However, the complexity in BR composition drives the need for developing a selective, efficient and cost-effective process to achieve the separation and purification of scandium. Insoluble salts of tetravalent metal ions are inorganic, acid-resistant ion exchangers with well-established preparation procedures, but their potential use in rare-earth recovery and purification has not been extensively explored yet. Zirconium and titanium phosphates, both in amorphous and α-layered crystalline forms, were screened for Sc(III)/Fe(III) separation, as Fe(III) is one of the base elements in BR that is the most challenging to separate from Sc(III). The studied α-zirconium phosphate (α-ZrP, Zr(HPO4)2·H2O) exhibited the highest Sc(III)/Fe(III) separation factors (up to approximately 23) from HCl solutions. The metal selectivity of α-ZrP was considered to be affected by the solution pH, and the size and hydration enthalpy of the metal cations. Breakthrough curves for a binary Sc(III)/Fe(III) solution, composed of metal concentrations realistic to a typical BR leachate, revealed the selectivity of α-ZrP for Sc(III). Furthermore, chromatographic separation of Sc(III) from a real HCl leachate of BR was successfully achieved on an α-ZrP column. After a two-step elution with HCl about 60 % of Sc(III) was collected in fractions without measurable Fe(III), Al(III) or other rare-earth impurities. Overall, this study highlights the possibility for direct and simplified separation of Sc(III) from a much higher concentration of Fe(III) in BR, without the need of using reducing agents.
  • Jarvinen, Ville; Halkoaho, Tapio; Konnunaho, Jukka; Heinonen, Jussi S.; Ramo, O. Tapani (2021)
    Several mafic-ultramafic layered intrusions were emplaced in the Fennoscandian Shield during wide-spread mantle-sourced magmatism at 2.5-2.4 Ga. The Narankavaara intrusion (surface area 5 x 30 km(2)), northeastern Finland, contains a 1.5-2 km thick basal dunite (not dated), and a 1.5 km thick layered series (2436 +/- 5 Ma). A newly discovered marginal series between the basal dunite and the layered series indicates that the basal dunite is older, and highlights the need for further study on their relationship. Along its southern basement contact, the basal dunite contains a 200-300 m thick zone of olivine ortho- and mesocumulates, but the bulk of it is composed of olivine adcumulates and lesser olivine-orthopyroxene heteradcumulates. Based on whole-rock geochemistry, the basal dunite is divided into a low-Fe zone (average FeOt 10.2 wt% and Ni 2250 ppm) and a high-Fe zone (average FeOt 12.5 wt% and Ni 1700 ppm). Both zones have high MgO (32-47 wt%) and varying Cr (830-5160 ppm) and Al2O3/TiO2 (16-26). Textural and geochemical layering is similar along the 30 km strike of the basal dunite. A LREE-enriched high-MgO basaltic parental magma composition (13-18 wt% MgO) is inferred for the basal dunite from olivine-melt mixing trends in orthocumulates. The dunite exhibits at least two geochemical reversals as well as abundant low-porosity adcumulates, poikilitic chromite, and bimodal olivine, suggesting formation in a high-volume open magmatic system. Significant similarity in major and trace element compositions with the Narankavaara layered series and the Burakovsky intrusion and Vetreny belt extrusives in Russian Karelia suggests that the basal dunite belongs to the Fennoscandian 2.5-2.4 Ga mafic layered intrusions. An Archean komatiitic origin for the dunite body cannot be completely ruled out, however. Distinct Ni-depletion in olivine is found in the basal dunite from the low-Fe zone to the high-Fe zone (3200 versus 2200 ppm). This depletion does not correlate with Fo contents, which suggests that it is not related to olivine fractionation. The basal dunite may thus have potential for Ni-(Cu-Co-PGE) sulfide mineralization.