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| 2. |
- Danielsson, Karin, et al.
(författare)
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Effects of the adsorption of NOM model molecules on the aggregation of TiO2 nanoparticles in aqueous suspensions
- 2018
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Ingår i: NanoImpact. - : Elsevier BV. - 2452-0748. ; 10, s. 177-187
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 Interaction of synthetic TiO2(anatase) nanoparticles in aqueous suspension at pH 5 was investigated as a function of time in the presence of various organic molecules in terms of adsorption and aggregation behaviour. ζ-potential and average particle diameter were determined with electrophoretic and dynamic light scattering, respectively, while batch adsorption experiments were used to quantify the amount of organic ligand adsorbed to the TiO2NP. An IR spectroscopic study was carried out at pH 2.8 and 5 to gain information about the interactions of the adsorbed molecules with the TiO2surface on the molecular level. Furthermore, DLVO calculations provided information about the interaction energies between particles and their tendency to aggregate under some experimental conditions. Colloidal stability of TiO2NPs in the presence of organic molecules was studied during a time period of up to 90 days. Results showed that ligands with different functional groups may interact differently with the surface depending on the type and position of available surface sites, the molecular structure of the ligand and suspension pH. Adsorption, hydrodynamic diameter and ζ-potential were affected by the ligand concentration in all tested systems. Increased concentration gave rise to increased adsorption, while ζ-potential decreased and charge inversion was observed for all tested molecules at pH 5. IR spectroscopic study showed the formation of inner sphere and/or outer sphere complexes depending on pH and type of organic ligand. According to DLVO calculations, the critical coagulation concentration (CCC) indicated a trend of increasing colloidal stability with increased concentration of SRFA at pH 5, which was in agreement with the experimental data.
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| 3. |
- Lundberg, Oscar, et al.
(författare)
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Adrenomedullin and endothelin-1 are associated with myocardial injury and death in septic shock patients
- 2016
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Ingår i: Critical Care. - : Springer Science and Business Media LLC. - 1364-8535 .- 1466-609X. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- AbstractBackgroundAdrenomedullin and endothelin-1 are hormones with opposing effects on the cardiovascular system. Adrenomedullin acts as a vasodilator and seems to be important for the initiation and continuation of the hyperdynamic circulatory response in sepsis. Endothelin-1 is a vasoconstrictor and has been linked to decreased cardiac performance. Few studies have studied the relationship between adrenomedullin and endothelin-1, and morbidity and mortality in septic shock patients. High-sensitivity troponin T (hsTNT) is normally used to diagnose acute cardiac injury but is also prognostic for outcome in intensive care. We investigated the relationship between mid-regional pro-adrenomedullin (MR-proADM), C-terminal pro-endothelin-1 (CT-proET-1), and myocardial injury, measured using transthoracic echocardiography and hsTNT in septic shock patients. We were also interested in the development of different biomarkers throughout the ICU stay, and how early measurements were related to mortality. Further, we assessed if a positive biomarker panel, consisting of MR-proADM, CT-proET-1, and hsTNT changed the odds for mortality.MethodsA cohort of 53 consecutive patients with septic shock had their levels of MR-proADM, CT-proET-1, hsTNT, and left ventricular systolic functions prospectively measured over 7 days. The relationship between day 1 levels of MR-proADM/CT-proET-1 and myocardial injury was studied. We also investigated the relationship between biomarkers and early (7-day) and later (28-day) mortality. Likelihood ratios, and pretest and posttest odds for mortality were calculated.ResultsLevels of MR-proADM and CT-proET-1 were significantly higher among patients with myocardial injury and were correlated with left ventricular systolic dysfunction. MR-proADM and hsTNT were significantly higher among 7-day and 28-day non-survivors. CT-proET-1 was also significantly higher among 28-day but not 7-day non-survivors. A positive biomarker panel consisting of the three biomarkers increased the odds for mortality 13-fold to 20-fold.ConclusionsMR-proADM and CT-proET-1 are associated with myocardial injury. A biomarker panel combining MR-proADM, CT-proET-1, and hsTNT increases the odds ratio for death, and may improve currently available scoring systems in critical care.Keywords: Sepsis, Shock, Adrenomedullin, Endothelin-1, High-sensitivity troponin, Echocardiography, Myocardial injury, Mortality, Likelihood ratio
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| 4. |
- Lutzenkirchen, J., et al.
(författare)
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The surface chemistry of sapphire-c: A literature review and a study on various factors influencing its IEP
- 2018
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Ingår i: Advances in Colloid and Interface Science. - : Elsevier BV. - 0001-8686 .- 1873-3727. ; 251, s. 1-25
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Forskningsöversikt (refereegranskat)abstract
- A wide range of isoelectric points (IEPs) has been reported in the literature for sapphire-c (alpha-alumina), also referred to as basal plane, (001) or (0001), single crystals. Interestingly, the available data suggest that the variation of IEPs is comparable to the range of IEPs encountered for particles, although single crystals should be much better defined in terms of surface structure. One explanation for the range of IEPs might be the obvious danger of contaminating the small surface areas of single crystal samples while exposing them to comparatively large solution reservoirs. Literature suggests that factors like origin of the sample, sample treatment or the method of investigation all have an influence on the surfaces and it is difficult to clearly separate the respective, individual effects. In the present study, we investigate cause-effect relationships to better understand the individual effects. The reference IEP of our samples is between 4 and 4.5. High temperature treatment tends to decrease the IEP of sapphire-c as does UV treatment. Increasing the initial miscut (i.e. the divergence from the expected orientation of the crystal) tends to increase the IEP as does plasma cleaning, which can be understood assuming that the surfaces have become less hydrophobic due to the presence of more and/or larger steps with increasing miscut or due to amorphisation of the surface caused by plasma cleaning. Pre-treatment at very high pH caused an increase in the IEP. Surface treatments that led to IEPs different from the stable value of reference samples typically resulted in surfaces that were strongly affected by subsequent exposure to water. The streaming potential data appear to relax to the reference sample behavior after a period of time of water exposure. Combination of the zeta potential measurements with AFM investigations support the idea that atomically smooth surfaces exhibit lower IEPs, while rougher surfaces (roughness on the order of nanometers) result in higher IEPs compared to reference samples. Two supplementary investigations resulted in either surprising or ambiguous results. On very rough surfaces (roughness on the order of micrometers) the IEP lowered compared to the reference sample with nanometer-scale roughness and transient behavior of the rough surfaces was observed. Furthermore, differences in the IEP as obtained from streaming potential and static colloid adhesion measurements may suggest that hydrodynamics play a role in streaming potential experiments. We finally relate surface diffraction data from previous studies to possible interpretations of our electroldnetic data to corroborate the presence of a water film that can explain the low IEP. Calculations show that the surface diffraction data are in line with the presence of a water film, however, they do not allow to unambiguously resolve critical features of this film which might explain the observed surface chemical characteristics like the dangling OH-bond reported in sum frequency generation studies. A broad literature review on properties of related surfaces shows that the presence of such water films could in many cases affect the interfacial properties. Persistence or not of the water film can be crucial. The presence of the water film can in principle affect important processes like ice-nucleation, wetting behavior, electric charging, etc. (C) 2017 Elsevier B.V. All rights reserved.
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| 5. |
- Magnér, Jörgen, et al.
(författare)
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Fate of pharmaceutical residues - in sewage treatment and on farmland fertilized with sludge
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Pharmaceutical products constitute a fundamental part of modern medicine and are in many cases crucial for health and wellbeing in our everyday life. However, the benefits from pharmaceutical come with drawbacks for the environment. These chemicals are designed to have a biological effect, which they unfortunately also might have on other living organisms than humans. They are moreover also considered to be semi-persistent due to the continuous discharge from our society. These characteristics make them problematic if they end up in the environment. For the last ten years pharmaceutical companies on the Swedish market can choose to publish environmental information about their products on the public web-based portal www.fass.se. Prior to publication the environmental information is reviewed by an external part (IVL Swedish Environmental Research Institute). Within the context as third party reviewer, IVL also performs research to increase the knowledge of pharmaceuticals in the environment to improve the reviewing process. This report describes the Fass research study conducted in 2014 and 2015. The focus of this study was to investigate the distribution and removal of a selection of pharmaceuticals within a sewage treatment plant (STP) and their final fate in the environment. For unclear reasons residues of pharmaceuticals can be represented in higher concentration in the effluent wastewater compared to the influent, which limits correct conclusions to be drawn regarding their removal during sewage treatment. Several studies on matrix effects and metabolism were performed to test different hypothesis that could explain the phenomena and to be able to estimate the “true” concentrations of pharmaceuticals within a STP. A mass balance was also performed to further study the pharmaceutical distribution. To assess the dispersion and fate of pharmaceuticals in the environment a farmland fertilized with sludge from the investigated STP were studied. Soil and sludge samples were analyzed as well as soil water collected by lysimeter techniques. In addition laboratory based soil sorption tests of the farmland soil exposed to pharmaceutical and sewage sludge were also performed. The result of the study showed that analytical interferences (ion-suppression) due to competition with co-eluting matrix components during instrumental analysis was the main contributor to the observed increase in concentration of pharmaceuticals from influent to effluent wastewater, with an average ion-suppression of 49% in influent wastewater and 35% in effluent wastewater of the investigated pharmaceuticals. Den här rapporten finns endast på engelska. Svensk sammanfattning finns i rapporten.
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| 6. |
- Persson, Per, et al.
(författare)
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Comparison of the adsorption of o-phthalate on boehmite (γ-AlOOH), aged γ-Al2O3, and goethite (α-FeOOH)
- 1988
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 206:1, s. 252-266
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Tidskriftsartikel (refereegranskat)abstract
- This work is concerned with the adsorption of o-phthalate (1,2-benzenedicarboxylate) at the water-metal (hydr)oxide interface. Previously published infrared spectroscopic, potentiometric, and adsorption data characterizing the boehmite (gamma-AlOOH) system are compared with new data collected for o-phthalate adsorption on aged gamma-Al2O3 and goethite (alpha-FeOOH). The study focuses on identifying bonding mechanisms, stoichiometries, and stabilities of the formed complexes, and comparing these among the three systems. Furthermore, the effects of ionic strength and composition of the ionic medium are investigated. The infrared spectroscopic data provided direct, molecular-level evidence for the existence of two dominating surface complexes on all three solids. One was shown to be a deprotonated outer-sphere species and the other was an inner-sphere surface complex. The inner-sphere complexes on the three solids were structurally related, and they were tentatively assigned to a mononuclear, chelating structure involving both carboxylate groups. The outer-sphere complexes were shown to increase in relative importance at high pH and low ionic strengths, while low pH and high ionic strengths favored the inner-sphere complexes. The information gained from the infrared spectroscopic investigations was used as qualitative input in the formulation of the surface complexation models. New models, based on the extended constant capacitance approach, were presented for the o-phthalate/aged gamma-Al2O3 and o-phthalate/goethite systems.
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| 7. |
- Rosenqvist, Jörgen, et al.
(författare)
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Adsorption of dicarboxylates on nano-sized gibbsite particles: effects of ligand structure on bonding mechanisms
- 2003
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Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects. ; 220:1-3, s. 91-104
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of the dicarboxylates o-phthalate, maleate, fumarate, malonate, and oxalate (representing ligands with the general composition −O2C---Cn---CO2−; n=0, 1, or 2) on gibbsite were studied by means of quantitative batch adsorption experiments and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The interpretations of ATR-FTIR spectra were aided by comparison with IR spectra of solution species and by results from theoretical frequency calculations. The main objectives of the study were to identify the molecular level bonding mechanisms of the dicarboxylates to gibbsite, and to investigate how these were influenced by the composition and structure of the ligands. Carboxylates with n=2 formed predominantly outer sphere complexes, whereas the importance of inner sphere complexes progressively increased for n=1 and 0. The inner sphere structures were identified as mononuclear chelates with one oxygen from each carboxylate group bonded to Al(III) at the surface. This showed the importance of chelate ring structure for the formation of inner sphere surface complexes, with stabilities of the complexes increasing in the order seven-membered ring less than six-membered ring less than five-membered ring. For ligands with n=2 only small variations in surface speciation were observed as a function of steric factors; irrespective of the relative positions of the carboxylate groups and bulkiness of the ligands outer sphere bonding is the dominating adsorption mode. Adsorption experiments were also conducted with gibbsite particles exhibiting differences in shape and surface roughness. These experiments showed that inner sphere complexes were favored on the less well-developed and more irregular gibbsite particles.
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