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  • 201.
    Engström, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mineralogical influence of different cooling conditions on leaching behaviour of steelmaking slags2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Swedish steelmaking industry produces large amounts of by-products. In 2006, the total amount of slag produced reached approximately 1 375 000 metric tons, of which 30% was deposited. Due to its strength, durability and chemistry, steel slag is of interest in the field of construction due to it's similarities with ordinary ballast stone. However, some steel slags face an array of quality concerns that might hinder their use. These concerns generally involve the following physical and chemical properties: Volume expansion, Disintegration, Leaching of metals By controlling and modifying process parameters during slag handling in liquid state, the physical properties of steel slags can be adequately modified to obtain a high-quality product for external application. The present work was undertaken as a research project within the Minerals and Metals Recycling Research Centre, MiMeR. The major objectives of this work have been to investigate how different cooling methods and cooling rates influence the properties of slag products. Four types of steel slags, Ladle slag, BOF (Basic Oxygen Furnace) slag and two different EAF (Electric Arc Furnace) slags, were characterized and modified by semi-rapid cooling in crucibles and rapid cooling by water granulation. Experiments were conducted in laboratory scale using an induction furnace. Analysis techniques used in this investigation include: thermodynamic calculations using FactSageTM, X-ray diffraction analyses (XRD), scanning electron microscope (SEM) and a standard leaching test (prEN 12457-2/3). The experimental results show that disintegrating ladle slag is volume stabilized by water granulation resulting in a product consisting of 98% glass. However EAF slag 1, EAF slag 2 and the BOF slag formed only 17%, 1% and 1% glass, respectively. The leaching tests showed that water granulation did not prevent leaching of minor elements from the modified slags. The solubility of chromium, molybdenum and vanadium varied in the different modifications, probably due to their presence in different minerals. Variations in crystal size as well as phase composition and distribution were observed in the different materials as a result of different cooling methods. The magnesium content of the wustite-type solid solution (Fe,Mg,Mn)O in BOF slag increased when rapid cooling was used. The reactivity factor, á, was calculated for the BOF and EAF slag 1. A majority of the elements of interests in the slags became more reactive when cooled rapidly. The reactivity for silica in BOF and EAF slag 1 was increased by ~4700% and ~1200%, respectively, and for chromium by ~5300% and ~1500%.

  • 202.
    Engström, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mineralogical influence on leaching behaviour of steelmaking slags: a laboratory investigation2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Swedish steelmaking industry produces large amounts of by-products. In 2008, the total amount of slag produced reached approximately 1,300,000 metric tons, of which 20% was deposited. Due to its strength, durability and chemistry, steel slag is of interest in the field of construction, since it has similar or better qualities than ordinary ballast stone, which makes it a competitive construction material. However, some steel slags face an array of quality concerns that might hinder their use. These concerns generally involve the following physical and chemical properties:Volume expansion Disintegration Leaching of metalsBy controlling and modifying process parameters during slag handling in liquid state, the physical and chemical properties of steel slags can be adequately modified to obtain a high-quality product for external application. The present work was undertaken as a research project within the Minerals and Metals Recycling Research Centre, MiMeR. The major goal of this work has been to investigate how different treatment methods including hot stage processing, cooling rates, ageing time and chemical composition influence the final properties of the slag. Analysis techniques used in this investigation include: thermodynamic calculations using FactsageTM, X-ray diffraction analyses (XRD), scanning electron microscopy (SEM), leaching tests (EN12457-2/3) and thermo-gravimetric analyses (TG).The results from this study show that it is possible to control/change the properties of the final product by additions to the liquid slag, thereby changing the chemical composition, as well as by varying the rate and method of cooling. The mineralogical composition, the size of the crystals and the composition of some solid solutions are affected by the cooling rate. The solubility of elements such as chromium and molybdenum varies, probably due to their presence in different minerals. The reactivity of the investigated slag samples increases as the cooling rate increases.When steel slags are aged, the leaching properties of the materials are changed. The total leachability and the pH decrease for all the investigated samples. All elements except magnesium decrease in leachability. As the slags are aged CaCO3 is formed on the slag surfaces. The degree of carbonation differs between different slags, due to the presence of different calcium-rich minerals in the slag. In order to form CaCO3, the calcium-containing mineral must be dissolved. This means that the solubility of the calcium-containing mineral will affect the outcome of the carbonation. The rate of dissolution for six typical slag minerals was investigated in order to distinguish the difference in solubility between the different minerals. Acidic to alkaline pHs (4, 7 and 10) were selected to investigate the solubility of the minerals under conditions comparable to those prevailing in newly produced slags and the potential future pH values obtained under acid conditions. It can be concluded that all six minerals behave differently when dissolving and that the rate of dissolution is generally slower at higher pH. At pH 10, the solubility of merwinite, akermanite and gehlenite is considered slow. The dissolution of γ-Ca2SiO4 is not affected in the same way as the other minerals when the pH is changed.

  • 203.
    Engström, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Adolfsson, Daniel
    SSAB EMEA, Luleå.
    Samuelsson, Caisa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sandström, Åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    A study of the solubility of pure slag minerals2013In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 41, p. 46-52Article in journal (Refereed)
    Abstract [en]

    Large amounts of oxidic by-product are annually produced by the steel industry worldwide. By far the largest in volume is slag, generated from different stages of steel production. In order to avoid landfilling, steelmakers usually try to process the slag into useful resources that can be used externally. However, leaching of different metals can sometimes be a problem. Since steel slags are a mixture of numerous types of minerals, the solubility of each mineral will affect the outcome of the leachability. The aim of this study was to investigate how six common slag minerals behave during dissolution. Mayenite (Ca12Al14O33), merwinite (Ca3MgSi2O8), akermanite (Ca2MgSi2O7), gehlenite (Ca2Al2SiO7), γ-dicalcium silicate (γ-Ca2SiO4) and tricalcium aluminate (Ca3Al2O6) were synthesized and their dissolution was evaluated through titration using HNO3 at constant pH. Acidic to alkaline pHs (4, 7 and 10) were selected to investigate the solubility of the minerals under conditions comparable to those prevailing in newly produced slags, and one pH value, representing acid conditions. It can be concluded that all six minerals behave differently when dissolving and that the rate of dissolution is generally slower at higher pH values, which are normal in the case of steelmaking slags. At pH 10, the solubility of merwinite, akermanite and gehlenite is considered low. The dissolution of γ-Ca2SiO4 is not affected in the same way as the other minerals when the pH is changed.

  • 204. Engström, Fredrik
    et al.
    Adolfsson, Daniel
    Yang, Qixing
    Samuelsson, Caisa
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Crystallization behaviour of some steelmaking slags2010In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 81, no 5, p. 362-371Article in journal (Refereed)
    Abstract [en]

    The present study was aimed at highlighting the final properties of two different steelmaking slags which undergo different cooling rates. The experiments were conducted in laboratory scale using an induction furnace. One of the slags originates from an electric arc furnace (EAF) (high-alloyed) and the second slag from a basic oxygen furnace (BOF). The treatment of the slag included re-melting along with different cooling rates. The material collected from the tests was characterized through X-ray diffraction, scanning electron microscopy as well as thermodynamic calculations which were compared with experimental results, for confirmation. The results indicate that both the EAF and BOF slags show increased reactivity with water, as well as a decrease in crystal size when rapid cooling is applied. The wüstite-type solid solution (Mg,Fe,Mn)O varies in composition depending on the cooling conditions. Metastable Ca3SiO5 was found in the rapidly- cooled BOF slag.

  • 205.
    Engström, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Lidström-Larsson, Margareta
    Samuelsson, Caisa
    Björkman, Bo
    Ageing investigation of steel slags from EAF (Electric Arc Furnace) processes2008In: REWAS 2008: Global Symposium on Recycling, Waste Treatment and Clean Technology / [ed] B Mishra; C Ludwig; S Das, Minerals, Metals & Materials Society, 2008, p. 353-358Conference paper (Refereed)
    Abstract [en]

    Large amounts of by-products are generated by the Swedish steel industry each year. The EAF-process generates about 400 000 ton of slag, from which 80% is deposit. An alternative to deposit is to use slag as road construction material. However, metal content in the slag can be a problem, due to the leaching. The aim of this work was to investigate how stable these materials are when ageing and kept outside. Five different EAF-slags from domestic steel plants were used in this study. The materials were characterised after 0, 6, 12, 18 and 24 month to evaluate the ageing process. Scanning electron microscope (SEM), x-ray diffraction pattern (XRD) and a standard test for leaching were used. The changes in behaviour differ between the five materials. The total leachability decreases with time for all samples. CaCO3 is formed on slag surfaces as CaO reacts with moister and CO2 in the air.

  • 206.
    Engström, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Pontikes, Yiannis
    Centre for High Temperature Process and Sustainable Materials Management, Department of Metallurgy and Materials Engineering, Katholieke University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Heverlee (Leuven), Belgium.
    Geysen, Daneel
    Centre for High Temperature Process and Sustainable Materials Management, Department of Metallurgy and Materials Engineering, Katholieke University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Heverlee (Leuven), Belgium.
    Jones, Peter Tom
    Centre for High Temperature Process and Sustainable Materials Management, Department of Metallurgy and Materials Engineering, Katholieke University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Heverlee (Leuven), Belgium.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Blanpain, Bart
    Centre for High Temperature Process and Sustainable Materials Management, Department of Metallurgy and Materials Engineering, Katholieke University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Heverlee (Leuven), Belgium.
    Review: Hot stage engineering to improve slag valorisation options2011In: Proceedings of the second international Slag Valorisation Symposium: : the transition to sustainable materials management : 18-20 April 2011, Leuven, Belgium / [ed] Peter Tom Jones, Leuven: Katholieke Universitat , 2011, p. 230-251Conference paper (Refereed)
    Abstract [en]

    A number of studies are briefly reviewed dealing with hot stage processing of slags, i.e. additions during the molten state and variations of the cooling path, and the influence on the microstructure and properties of solidified slags. Emphasis is placed on research and developments in the last five years, although other works that created the thinking framework for several of the current practices are also mentioned. The additions include: a) quartz sand with concurrent oxygen injection for the minimisation of free CaO and MgO, b) various materials for the modification of the composition of liquid blast furnace slag after tapping, c) borates and boron wastes and their distribution in both synthetic and industrial stainless steel slags, d) phosphates in stainless steel slags and their distribution in BOF slags e) waste glass and fly ash for the stabilisation of stainless steel slags, f) K2CO3 for the production of potassium silicate fertiliser from steelmaking slag and g) bauxite, Al2O3 containing residues and aluminium metal that enhance the Cr recovery and minimise leaching in EAF slags. In terms of cooling, the effect of cooling rate on the final mineralogy, as a way to stabilise stainless steel slags and to control free lime formation in BOF slags, is presented. A more in-depth discussion regarding leaching performance, which has been identified as a key issue in slag valorisation, is also taking place. Although it is acknowledged that many research questions are still open and that both technical and economical barriers exist, it is strongly believed that a conscious hot stage processing step can both increase slag utilisation rates and make higher value applications achievable.

  • 207.
    Engström, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Samuelsson, Caisa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mineralogical influence of different cooling conditions on leaching behavior of steelmaking slags2009Conference paper (Other academic)
  • 208.
    Engström, V.
    et al.
    Luleå tekniska universitet.
    Mihailova, Boriana
    Bulgarian Academy of Sciences.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Holmgren, Allan
    Sterte, Johan
    The effect of seed size on the growth of silicalite-1 films on gold surfaces2000In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 38, no 1, p. 51-60Article in journal (Refereed)
    Abstract [en]

    Silicalite-1 films grown on gold surfaces seeded with colloidal crystals with a size of 60, 165 and 320 nm were investigated by reflection–absorption infrared spectroscopy, scanning electron microscopy and X-ray diffraction in order to follow up the formation of nano-scale defects and to determine the optimal synthesis conditions for preparation of silicalite-1 films with a low concentration of defects. Using 60-nm-sized colloidal crystals, the seeding method was capable of producing silicalite-1 films with low concentrations of defects and with thicknesses ranging from 100 to 300 nm, which are predominantly oriented with the a-axis perpendicular to the surface. Hydrothermal treatment times of the 60-nm-seeded surfaces longer than 36 h as well as the seeding with 165 or 320 nm colloidal crystals substantially enhanced the formation of defects in the films.

  • 209.
    Enman, Josefine
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Fungal production and solid state chemistry of eritadenine: an integrated approach to development of an active pharmaceutical ingredient2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present thesis demonstrates an integrated approach to the development of a potential active pharmaceutical ingredient, eritadenine, a cholesterol reducing compound originating from the shiitake mushroom (Lentinus edodes). The main areas covered in the thesis are a method for quantification of eritadenine, production of eritadenine by submerged cultivation of fungal mycelia and investigation of the influence of process parameters on mycelial growth and production, and finally solid state characterizations of eritadenine. The usage of the fungus as a source of eritadenine requires an analytical tool for quantification of the compound. An HPLC method was hence developed for identification and quantification of eritadenine, using chemically synthesized eritadenine as a reference. The amount of eritadenine in fruit bodies of selected strains of shiitake was determined and with the method developed in this study, eritadenine concentrations up to ten times higher than previously reported were detected. Since both fruit bodies and mycelia of shiitake have been shown to contain eritadenine submerged cultivation of shiitake mycelia was investigated as an alternative source for this compound. The mycelia were cultivated in various submerged conditions, both in shake flasks and in bioreactors. It was found that both the mycelia and the culture media contained eritadenine, of which the major part was detected in the culture media. While the biomass concentrations were higher in shake flasks, the eritadenine concentrations were considerably higher in the bioreactors, which were assigned to morphological variations. In an attempt to improve the mycelial growth and eritadenine production, a growth promotive substance in the form of a water extract of DDGS, a by-product from drygrind ethanol facilities, was added to the culture media. It was demonstrated that an amendment of the cultivation media with this extract caused a considerable growth promotive effect on shiitake mycelia in bioreactor cultivations, along with enhanced eritadenine production. If eritadenine will be used as a pharmaceutical agent, understanding about the solid state chemistry of the compound is required. Raman spectroscopy is a valuable technique for investigation of structural properties; hence, a Raman reference spectrum with line assignments for the solid state of synthetic eritadenine was established. To further investigate the solid state chemistry of eritadenine, its synthetic analogue was slowly crystallized from water and different ethanol concentrations, at different temperatures. Solids formed from slow cooling of either water or aqueous ethanol showed crystallinity. No polymorphism was detected, irrespective of solvent system or temperature. However, dissimilar thermal behaviours were observed, deducing crystals derived from water as dihydrates and crystals derived from aqueous ethanol as 2.5 hydrates.

  • 210.
    Enman, Josefine
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Production and quantification of eritadenine, a cholesterol reducing compound in shiitake (Lentinus edodes)2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cardiovascular diseases are among the main causes of death in our society and there is a strong correlation between enhanced blood cholesterol levels and the development of such diseases. The popular edible fungus, shiitake mushroom (Lentinus edodes), has been shown to produce a blood cholesterol lowering compound designated eritadenine, and the hypocholesterolemic action of this compound has been quite extensively examined in rats. Eritadenine is suggested to accelerate the removal of blood cholesterol either by stimulating tissue uptake or by inhibiting tissue release; there are no indications of this compound inhibiting the biosynthesis of cholesterol. If shiitake mushrooms are to be used as a source for a potential cholesterol reducing product, it is of great importance to determine the content of eritadenine in the mushrooms as accurately as possible. Hence, in paper I methanol extraction was used to recover as much as possible of the hypocholesterolemic agent from the fungal cells. In order to analyse the target compound, a reliable and reproducible HPLC method for separation, identification and quantification of eritadenine was developed. The amounts of eritadenine in fruit bodies of four commercially cultivated shiitake mushrooms were determined, and the mushrooms under investigation exhibited up to ten times higher levels of eritadenine (3.17-6.33 mg/g dry mushrooms) than previously reported. Not only the fruit bodies of shiitake, but also its mycelia contain eritadenine. Growing fruit bodies of shiitake is a fairly demanding and time consuming process. Hence, in search for a source of eritadenine, submerged (liquid) cultivation of shiitake mycelia could be an alternative. The reason why shiitake mushrooms synthesize eritadenine is yet not clarified; i.e. the function of this secondary metabolite and the growth conditions that favour its production are not elucidated. In addition, like other filamentous fungi, shiitake exhibits different hyphal morphologies in submerged cultures depending on cultivation conditions such as medium composition, temperature, pH, inoculum concentration, dissolved oxygen and shear. The fungal metabolism and hence production of secondary metabolites is in turn affected by the morphology, as have been shown in several studies on filamentous fungi. Submerged cultivation of shiitake mycelia offers a convenient way to change the cultivating conditions in order to improve eritadenine yield and productivity. The study in paper II focused on cultivation of mycelia at different conditions, both in shake flasks and in bioreactors, to investigate the effect of pH and stirring rate on production of eritadenine. The shiitake mycelia were found to produce eritadenine, and the compound of interest was found in both the fungal cells and the growth media. The major part (90-99%) was found in the culture medium, which offers a facilitated downstream processing if large scale production of the compound is to be conducted. The mycelial morphology in the shake flask cultures were macroscopic aggregates, pellets, and the specific productivity of eritadenine was relatively low; 6.56 mg/g dry cell weight (DCW). In the bioreactor cultivations, the mycelia grew as freely dispersed filaments, showing a higher specific productivity than in the shake flasks, ranging between 26.00- 39.58 mg/g DCW. This indicates the influence of morphology on eritadenine production. The biomass yield in shake flasks and bioreactors was in parity; 0.45 g in the shake flasks and 0.25- 0.62 g in the bioreactors. A stirring rate of 50 rpm in the bioreactors was preferable for eritadenine production, whereas for biomass production it was 250 rpm, indicating the influence of agitation on both growth and productivity. The pH did not have any major impact on growth, whereas the specific productivity in the bioreactors was higher when pH was uncontrolled than controlled at 5.7.

  • 211.
    Enman, Josefine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hodge, David
    Berglund, Kris
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Growth promotive conditions for enhanced eritadenine production during submerged cultivation of Lentinus edodes2012In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 87, no 7, p. 903-907Article in journal (Refereed)
    Abstract [en]

    Background: Mycelium of the medicinal mushroom shiitake, Lentinus edodes, is a potential source for production of the blood cholesterol reducing compound eritadenine. To increase the mycelial biomass and in turn the production of eritadenine, a potential growth promoting substance in the form of a water extract of distillers dried grains with solubles (DDGS) was added to the culture media. Results: The hot water extract of DDGS was shown to considerably increase the growth of shiitake mycelia in bioreactor cultivations; the mycelial yield was 2-3 times higher than in the control, and the highest final biomass concentration obtained was 3.4 g L -1. Further, by using shake flask cultures as inoculums the bioreactor cultivation time could be reduced by 1 week for some of the experiments. The highest final titer of eritadenine in the present study was 25.1 mg L -1, which was about 2 times higher than in the control, and was also obtained when a water extract of DDGS was added to the culture medium. Conclusion: It was demonstrated that a water extract of DDGS promoted the growth of shiitake mycelia in bioreactor cultivations, along with enhanced eritadenine production

  • 212.
    Enman, Josefine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hodge, David
    Berglund, Kris
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rova, Ulrika
    Production of the bioactive compound eritadenine by submerged cultivation of shiitake (Lentinus edodes) mycelia2008In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 56, no 8, p. 2609-2612Article in journal (Refereed)
    Abstract [en]

    Fruit bodies and mycelia of shiitake mushroom (Lentinus edodes) have been shown to contain the cholesterol-reducing compound eritadenine, 2(R),3(R)-dihydroxy-4-(9-adenyl)butyric acid. In the search for a production method for eritadenine, shiitake mycelia were investigated in the present study. The mycelia were cultivated both in shake flasks and in bioreactors, to investigate the effects of pH, stirring rate, and reactor type on the production and distribution of eritadenine. Both the biomass and the culture broth were examined for their eritadenine content. In the shake flasks, the final concentration of eritadenine was 1.76 mg/L and eritadenine was equally distributed between the mycelia and the growth media. In the bioreactors, the shiitake mycelia were found to contain eritadenine in relatively low levels, whereas the majority, 90.6-98.9%, was detected in the growth media. Applying a stirring rate of 250 rpm during bioreactor cultivation resulted in the highest eritadenine concentrations: 10.23 mg/L when the pH was uncontrolled and 9.59 mg/L when the pH was controlled at 5.7. Reducing the stirring rate to 50 rpm resulted in a decreased eritadenine concentration, both at pH 5.7 (5.25 mg/L) and when pH was not controlled (5.50 mg/L). The mycelia in the shake flask cultures appeared as macroscopic aggregates, whereas mycelia cultivated in bioreactors grew more as freely dispersed filaments. This study demonstrates for the first time the extra- and intracellular distribution of eritadenine produced by shiitake mycelial culture and the influence of reactor conditions on the mycelial morphology and eritadenine concentrations.

  • 213.
    Enman, Josefine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Patra, Anuttam
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Ramser, Kerstin
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Berglund, Kris
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Solid state characterization of sodium eritadenate2011In: American Journal of Analytical Chemistry, ISSN 2156-8251, E-ISSN 2156-8278, Vol. 2, no 2, p. 164-173Article in journal (Refereed)
    Abstract [en]

    Knowledge of the solid state is of great importance in the development of a new active pharmaceutical ingredient, since the solid form often dictates the properties and performance of the drug. In the present study, solid state characteristics of the sodium salt of the candidate cholesterol reducing compound eritadenine, 2(R), 3(R))-dihydroxy-4-(9-adenyl)-butanoic acid, were investigated. The compound was crystallized by slow cooling from water and various aqueous ethanol solutions, at different temperatures. Further, the compound solution was subjected to lyophilization and to high vacuum drying. The resulting solids were screened for polymorphism by micro Raman spectroscopy (λex = 830 nm) and the crystallinity was investigated by X-ray powder diffraction. Further, thermal analysis was applied to study possible occurrence of solvates or hydrates. Solids obtained from slow cooling showed crystallinity, whereas rapid cooling gave rise to more amorphous solids. Analysis of difference spectra of the Raman data for solids obtained from slow cooling of solution revealed subtle differences in the structures between crystals derived from pure water and crystals derived from aqueous ethanol solutions. Finally, from the thermal analysis it was deduced that crystals obtained from pure water were stoichiometrically dihydrates whereas crystals obtained from aqueous ethanol solutions were 2.5 hydrates; this formation of different hydrates were supported by the Raman difference analysis.

  • 214.
    Enman, Josefine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Ramser, Kerstin
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Rova, Ulrika
    Berglund, Kris
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Raman analysis of synthetic eritadenine2008In: Journal of Raman Spectroscopy, ISSN 0377-0486, E-ISSN 1097-4555, Vol. 39, no 10, p. 1464-1468Article in journal (Refereed)
    Abstract [en]

    Eritadenine, 2(R),3(R)-dihydroxy-4-(9-adenyl)-butyric acid, is a cholesterol-reducing compound naturally occurring in the shitake mushroom (Lentinus edodes). To identify the unknown Raman spectrum of this compound, pure synthetic eritadenine was examined and the vibrational modes were assigned by following the synthesis pathway. This was accomplished by comparing the known spectra of the starting compounds adenine and D-ribose with the spectra of a synthesis intermediate, methyl 5-(6-Aminopurin-9H-9-yl)-2,3-O-isopropylidene-5-deoxy-β-D-ribofuranoside (MAIR) and eritadenine. In the Raman spectrum of eritadenine, a distinctive vibrational mode at 773 cm-1 was detected and ascribed to vibrations in the carbon chain, ν(C--C). A Raman line that arose at 1212 cm-1, both in the Raman spectrum of MAIR and eritadenine, was also assigned to ν(C--C). Additional Raman lines detected at 1526 and at 1583 cm-1 in the Raman spectrum of MAIR and eritadenine were assigned to ν(N--C) and a deformation of the purine ring structure. In these cases the vibrational modes are due to the linkage between adenine and the ribofuranoside moiety for MAIR, and between adenine and the carbon chain for eritadenine. This link is also the cause for the disappearance of adenine specific Raman lines in the spectrum of both MAIR and eritadenine. Several vibrations observed in the spectrum of D-ribose were not observed in the Raman spectrum of eritadenine due to the absence of the ribose ring structure. In the Raman spectrum of MAIR some of the D-ribose specific Raman lines disappeared due to the introduction of methyl and isopropylidene moieties to the ribose unit. With the approach presented in this study the so far unknown Raman spectrum of eritadenine could be successfully identified and is presented here for the first time.

  • 215.
    Enman, Josefine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rova, Ulrika
    Berglund, Kris A.
    Quantification of the bioactive compound eritadenine in selected strains of shiitake mushroom (Lentinus edodes)2007In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 55, no 4, p. 1177-1180Article in journal (Refereed)
    Abstract [en]

    Cardiovascular disease is one of the most common causes of death in the Western world, and a high level of blood cholesterol is considered a risk factor. The edible fungus, shiitake mushroom (Lentinus edodes), contains the hypocholesterolemic agent eritadenine, 2(R),3(R)-dihydroxy-4-(9-adenyl)-butyric acid. This study was conducted to quantify the amount of the cholesterol reducing agent eritadenine in shiitake mushrooms, in search of a potential natural medicine against blood cholesterol. The amounts of eritadenine in the fruit bodies of four different shiitake mushrooms, Le-1, Le-2, Le-A, and Le-B, were investigated in this study. To achieve this goal, methanol extraction was used to recover as much as possible of the hypocholesterolemic agent from the fungal cells. In addition, enzymes that degrade the fungal cell walls were also used to elucidate if the extraction could be further enhanced. To analyze the target compound, a reliable and reproducible HPLC method for separation, identification, and quantification of eritadenine was developed. The shiitake strains under investigation exhibit up to 10 times higher levels of eritadenine than previously reported for other shiitake strains. Further, pretreating the mushrooms with hydrolytic enzymes before methanol extraction resulted in an insignificant increase in the amount of eritadenine released. These results indicate the potential for delivery of therapeutic amounts of eritadenine from the ingestion of extracts or dried concentrates of shiitake mushroom strains.

  • 216.
    Eriksson, Johan
    et al.
    Luleå tekniska universitet.
    Ping, Ma
    Luleå tekniska universitet.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Zander, Bo
    Utilisation of oily mill scale sludge as scrap resource1999In: REWAS '99: Global Symposium on Recycling, Waste Treatment and Clean Technology ; proceedings of the "REWAS'99: Global Symposium on Recycling, Waste Treatment and Clean Technology", held in San Sebastián, Spain, September 5 - 9, 1999 ; TMS Fall 1999 Extraction and Process Metallurgy Meeting / [ed] I. Gaballah, 1999, p. 1423-1430Conference paper (Refereed)
    Abstract [en]

    This paper presents the results of reduction trials of oily mill scale sludge. Laboratory experiments and two campaigns in a pilot plant rotary kiln have been carried out. The results indicate that it's possible to reduce oily mill scale sludge to sponge iron in the rotary kiln. The first pilot plant campaign was carried out with a mix of 75 wt-% mill scales and 25 wt-% mill scale sludge. During the second campaign 100 wt-% oily mill scale sludge were mixed with blast furnace flue dust and reduced. Petroleum coke has been used as the main reductant in both campaigns. Smelting trials of the sponge iron product have also been carried out in a production EAF. The sponge iron was charged into the scrap bin in big-bags. These trials showed that the degree of metallization of the sponge iron must be higher than 55% to avoid an increased iron oxide content in the slag, i.e. a low iron yield to the metal

  • 217.
    F., Su
    et al.
    Luleå University of Technology.
    Rao, K. Hanumantha
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Samskog, Per-Olof
    Computer estimation of flotation kinetic model parameters1998In: 2Papers presented at the APCOM '98 conference, organized by the Institution of Mining and Metallurgy and held in London, United Kingdom from 19 to 23 April, 1998, London: The Institution of Mining and Metallurgy , 1998, p. 513-524Conference paper (Refereed)
    Abstract [en]

    The effect of chemical variables on the kinetic parameters of apatite flotation from magnetite has been investigated. The two common first-order kinetic models reported in the literature, i.e., the model with rectangular distribution of floatabilities and the model with fast and slow-floating components (F-S model) have been applied in the evaluation of flotation results. The models are evaluated by fitting the flotation results from batch flotation tests. The results although indicate that both models describe the apatite flotation kinetics well in a wide range of kinetic parameters, the F-S model is found to be better in the goodness of fit to the results from every flotation test and also to describe the flotation performance adequately. The kinetic parameters of the F-S model are varied with a change in chemical variables. In particular, the rate constants ratio Kf/Ks is found to be an important parameter for achieving selectivity between apatite and magnetite, and the effect of reagents dosages on the ratio is discussed. The effect of particle size on the apatite flotation kinetics is also illustrated by analysing the froth products at each flotation time in different size classes.

  • 218.
    Falcon, Javier A.
    et al.
    Michigan State University.
    Berglund, Kris
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Monitoring of antisolvent addition crystallization with Raman spectroscopy2003In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 3, no 6, p. 947-952Article in journal (Refereed)
    Abstract [en]

    Fiber optic Raman spectroscopy was used for in situ monitoring of antisolvent addition crystallization of cortisone acetate. Raman spectral features of the solvent, the antisolvent, and the solute were monitored to measure the relative concentration of the components. Different rates of antisolvent addition were monitored and the resulting solid-state form was characterized using Raman spectroscopy and DSC. Raman spectroscopy was used to monitor dehydration during storage of the product crystals. The current study demonstrates the advantages of using Raman spectroscopy to monitor the solution phase during crystallization and simultaneously monitoring the solid-state form.

  • 219.
    Fatima, Nowshir
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Marklund, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Mathew, Aji P.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Degradation mechanism of water contaminated automatic transmission fluid (ATF) in wet clutch system2013Conference paper (Refereed)
  • 220.
    Felippov, A.
    et al.
    Umeå university.
    Sulejmanova, A.
    Kazan State University, Tatarstan.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Grobner, G.
    Umeå university.
    Diffusion and aggregation of Alzheimer's Aβ1-40 peptide in aqueous trifluoroethanol solutions as studied by pulsed field gradient NMR2005In: Applied Magnetic Resonance, ISSN 0937-9347, E-ISSN 1613-7507, Vol. 29, no 3, p. 439-449Article in journal (Refereed)
    Abstract [en]

    Pulsed field gradient nuclear magnetic resonance technique was applied to measure the self-diffusion coefficient of Aβ1-40 peptide in trifluoroethanol (TFE) and mixed solvent TFE-water (D2O) buffer (pD 7.8) at 293 K. The data were analyzed on the basis of the Stokes model and the hard-sphere approach was used to estimate self-diffusion coefficients. It was found that the extent of the Aβ1-40 aggregation in TFE solutions depends on the concentration of the peptide and the sample preparation protocol. After soft mixing, i.e., without any additional mechanical pretreatment of the peptide, the peptide is present in the monomeric form in TFE solutions. However, the additional water-bath sonication of the sample during the dissolution of Aβ1-40 in TFE enforces oligomerization of the peptide with the size of aggregates ranging from tetra- to hexamers. An increase of D2O in the mixed TFE-D2O solvent of up to 75% leads to the aggregation of the larger part of the peptide. However, the components of self-diffusion coefficients related to low-mass Aβ1-40 oligomers (dimers and trimers) were not observed in the diffusion decay curves. The most probable explanation is that dimers and trimers are not the principal intermediate species in the aggregation of Aβ1-40 peptide (23 refs.)

  • 221.
    Feng, Lili
    et al.
    Michigan State University.
    Berglund, Kris
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    ATR-FTIR for determining optimal cooling curves for batch crystallization of succinic acid2002In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 2, no 5, p. 449-452Article in journal (Refereed)
    Abstract [en]

    The temperature profile applied during batch cooling crystallization affects the supersaturation level, which in turn affects the crystal size distribution. It is possible, in principle, to calculate the optimal cooling profile; however, the nucleation and growth kinetics are rarely known to the degree of accuracy necessary for this calculation. The current study demonstrates an alternative approach to determination of the optimal cooling profile without any prior knowledge of kinetic data or subsequent modeling. An attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometer was used to monitor the supersaturation level during batch cooling crystallization. The ATR-FTIR was interfaced to a LABMAX automatic reactor system that was used in a feedback mode to control the cooling rate so that the supersaturation level remained close to the solubility throughout the cooling process. The resulting temperature profile corresponds to the optimal operating conditions for the maximum in the mean crystal size.

  • 222.
    Feng, X.
    et al.
    Stockholms Universitet.
    Edén, M.
    Stockholms Universitet.
    Brinkmann, A.
    Stockholms Universitet.
    Luthman, H.
    Eriksson, L.
    Gräslund, A.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Levitt, M.H.
    Direct determination of a peptide torsional angle Ψ by double-quantum solid-state NMR1997In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 119, p. 12006-12007Article in journal (Other academic)
  • 223.
    Filippov, A. V.
    et al.
    Kazan State University, Tatarstan.
    Suleimanova, A. V.
    Kazan State University, Tatarstan.
    Grobner, G.
    Umea University, Department of Chemistry.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Effect of freezing on amyloid peptide aggregation and self-diffusion in an aqueous solution2008In: Colloid Journal of the Russian Academy of Science, ISSN 1061-933X, E-ISSN 1608-3067, Vol. 70, no 4, p. 501-506Article in journal (Refereed)
    Abstract [en]

    Pulsed-field gradient 1H NMR is employed to investigate the self-diffusion of amyloid Aβ-peptide in an aqueous buffer solution (pH 7.44) with a protein concentration of 50 μmol at 20°C. The self-diffusion coefficient of the peptide in a freshly prepared solution corresponds to its monomeric form. The storage of the solution at 24°C causes part of the peptide molecules to form amyloid aggregates as soon as over 48 h. However, the 1H NMR echo signal typical of aggregated molecules is not observed because of their dense packing in the aggregates and a large mass of the latter. A freezing-fusion of the solution after the aggregation does not cause changes in the self-diffusion coefficients of the peptide. After a peptide solution free of amyloid aggregates is subjected to a freezing-fusion cycle, part of the peptide molecules also remains in the monomeric form in the solution, while another part forms amyloid aggregates, with a portion of the aggregated peptide molecules retaining a high rotational mobility with virtually absolute absence of a translational mobility. The results obtained are interpreted in terms of the formation of "porous aggregates" of amyloid fibrils, with "pores" having sizes comparable with those of peptide molecules, though, being larger than water molecules. Peptide molecules, which do not form fibrils, are captured in the pores. Temperature regime is shown to be of importance for the aggregation of amyloid peptides. In particular, freezing, which is traditionally considered to be a method for the prevention from or temporary interruption of aggregation, may itself lead to the formation of amorphous amyloid aggregates, which remain preserved in solutions after their unfreezing.

  • 224.
    Filippov, Andrei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Synthesis and aggregation studies on amyloid oligomers of Alzheimer's Ab peptides2010Licentiate thesis, comprehensive summary (Other academic)
  • 225.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Influence of Alzheimer´s beta-amyloid peptide on the lateral diffusion of lipids in raft-forming bilayers2013In: Mendeleev communications (Print), ISSN 0959-9436, E-ISSN 1364-551X, Vol. 23, no 6, p. 316-318Article in journal (Refereed)
    Abstract [en]

    For the first time effect of added Alzheimer´s Abeta(1-40) peptide of wild type on lateral diffusion of lipids in macroscopically oriented bilayers of “raft” compositions (mixture of dioleoylphosphatidylcholine (DOPC), sphingomielin (SM) and cholesterol (CHOL)) was studied by NMR-diffusion technique. In homogeneous bilayers diffusion coefficients decrease, while in liquid ordered and in liquid disordered phases they change differently at varied concentrations of CHOL that was explained by decreased maximum solubility of CHOL in phospholipids in the presence of Abeta(1-40) peptide.

  • 226.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Artamonova, Marina
    Kazan (Volga Region) Federal University, Kazan.
    Rudakova, Maya
    Kazan (Volga Region) Federal University, Kazan.
    Gimatdinov, Roustam
    Kazan (Volga Region) Federal University, Kazan.
    Skirda, Vladimir
    Kazan (Volga Region) Federal University, Kazan.
    Self-diffusion in a hyaluronic acid–albumin–water system as studied by NMR2012In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 50, no 2, p. 114-119Article in journal (Refereed)
    Abstract [en]

    In the presence of even a small amount of hyaluronic acid, the self-diffusion coefficient of albumin decreases. Three hypotheses were proposed and analyzed. The most likely one is that BSA and HA molecules form complex. The state of the BSA molecules in the BSA-HA-D2O system corresponds to a ‘fast exchange’ condition from the NMR point of view: BSA molecules reside in the ‘free’ and ‘bound’ states for much shorter time than the diffusion time of the PFG NMR experiment. Hyaluronic acid (HA) is an anionic biopolymer that is present in many tissues and can be involved in cancerous neoformations. HA can form complexes with proteins (particularly, serum albumin) in the body. However, HA structures and processes involving HA have not been extensively studied by NMR because the molecule's rigid structure makes these studies problematic. In the current work, self-diffusion of HA and bovine serum albumin (BSA), and water in solutions was measured by 1H pulsed field gradient NMR (PFG NMR) with a focus on the HA-BSA-D2O systems at various concentrations of BSA and HA. It was shown that in the presence of even a small amount of HA, the self-diffusion coefficient (SDC) of BSA decreases. To explain this fact, three hypotheses were proposed and analyzed. The first one was based on the effect of slowing down of water mobility in the presence of HA. The second hypothesis suggested an effect of mechanical collisions of BSA with HA molecules. The third hypothesized that BSA and HA molecules form a complex where BSA molecules reduced in mobility. It was shown that the third mechanism is the most likely. The state of the BSA molecules in the BSA-HA-D2O system corresponds to a ‘fast exchange’ condition from the NMR point of view: BSA molecules reside in the ‘free’ and ‘bound’ (with HA) states for much shorter time than the diffusion time of the PFG NMR experiment, 7 ms. The fractions of ‘bound’ BSA molecules in the BSA-HA complex were estimated.

  • 227.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Dvinskikh, Sergey V.
    Royal Institute of Technology.
    Khakimov, Aidar
    Kazan (Volga Region) Federal University, Kazan.
    Grahn, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Zhou, Han
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Furo, Istvan
    Royal Institute of Technology.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Dynamic properties of water in silicalite-1 powder2012In: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 30, no 7, p. 1022-1031Article in journal (Refereed)
    Abstract [en]

    Self-diffusion of D 2O in partially filled silicalite-1 crystals was studied at 25°C by 2H nuclear magnetic resonance (NMR) with bipolar field gradient pulses and longitudinal Eddy-current-delay. For the first time, reliable experimental diffusion data for this system were obtained. Analysis of NMR diffusion decays revealed the presence of a continuous distribution of apparent self-diffusion coefficients (SDCs) of water, ranging from 10 -7 to ~10 -10 m 2/s, which include values much higher and lower than that of bulk water (~10 -9 m 2/s) in liquid phase. The observed distribution of SDC changes with variation of the diffusion time in the range of 10-200 ms. A two-site Kärger exchange model was successfully fitted to the data. Finally, the water distribution and exchange in silicalite-1 pores were described by taking into account (a) a gas-like phase in the zeolite pores, a gas-like phase in mesopores and an intercrystalline gas-like phase and (b) intercrystalline liquid droplets with intermediate exchange rate with the other phases. The other phases experience fast exchange on the NMR diffusion time scale. Diffusion coefficients and mean residence times of water in some of these states were estimated

  • 228. Filippov, Andrei
    et al.
    Gröbner, G.
    Umeå university.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Alzheimer's Ab(1-40)-peptide aggregation in TFE caused by ultrasonication2009In: International Bunsen Discussion Meeting on "Structure of Amyloid Fibrils and Mechanism of Amyloid Formation", 8-11 February 2009, Halle an der Saale (Germany): Abstract Book, 2009, p. 15-Conference paper (Other academic)
    Abstract [en]

    The translational diffusion of Alzheimer's Aβ(1-40)-peptide in sonicated trifluoroethanol (TFE) solutions was studied by the 1H NMR-diffusomery technique. Sonication was performed at the ultrasound frequency of 50 kHz and with the output of 80 W. In freshly-prepared solutions (without any preaggregates of the peptide) diffusion of Aβ(1-40) can be described by an unique diffusion coefficient (~1×10-10 m2/s), which corresponds to the calculated diffusion coefficient of Aβ(1-40) monomers using the Stokes-Einstein hard-sphere approximation. For untreated samples both the diffusion coefficient and the NMR signal amplitude were not changing with time that suggests no aggregation of the peptide in TFE. In contrary, the diffusion decay of the stimulated spin-echo in sonicated samples was more complex suggesting a presence of a few components with different diffusion coefficients. The diffusion decay was separated into spectral components using the CORE method for global analysis of correlated spectral data. This analysis revealed a new diffusion component, which is characterized by a very small diffusion coefficient (<1×10-13 m2/s), which may be attributed to large oligomers of Aβ(1-40) formed upon sonication. A fraction of this component from the total integral intensity of the 1H NMR signal does depend on the sonication time but it does not change during NMR measurements and the following storage of the sample. In all samples a large fraction of the peptide adopts the a-helical secondary structure as revealed by circular dichroism measurements. Upon ultrasonication this secondary structure changes only insignificantly. Therefore, ultrasonication leads to aggregation of Aβ(1-40)-peptide in TFE, without a detectable (by CD) disruption of its a-helical secondary structure.  An increase in the integral intensity of the 1H NMR signal in sonicated samples of Aβ(1-40) in TFE may be interpreted in terms of the transverse relaxation times, T2, of the solvent and Aβ(1-40) monomers: these times do increase as the fraction of Aβ(1-40) aggregates increases in the sample upon sonication. This effect can be further explained by either a concentration dependence of T2 (that reflects a changing ratio of "free" and "bound" solvent to the peptide molecules) or/and by a conformational change in Aβ(1-40) monomers as a result of sonication. Additional spin-echo T2-relaxation time measurements and 1H 2D NOESY NMR may assist in understanding of these interesting effects in sonicated solutions of Aβ(1-40) in TFE. Putative aggregation mechanisms and structures of monomers and oligomers in Aβ(1‑40)/TFE solutions at different duration of sonication are also discussed.

  • 229. Filippov, Andrei
    et al.
    Gröbner, G.
    Umeå university.
    Klochkov, V.
    Kazan State University, Tatarstan.
    Julmetov, A.
    Kazan State University, Tatarstan.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Aggregation on an amyloid peptide as studied by NMR diffusometry and 2D NMR noesy spectroscopy2009In: Protein folds in infectious and neurodegenerative diseases, Centre National de la Recherche Scientifique, CNRS , 2009, p. 91-Conference paper (Other academic)
    Abstract [en]

    Alzheimer's disease is a progressive neurodegenerative disorder affecting millions of people world-wide. Alzheimer's amyloid-b peptide forms amorphous aggregates or amyloid fibrils. However, recent studies indicate that soluble oligomers instead of fibrils may form probably most neurotoxic species. These oligomeric aggregates are difficult to study by traditional structural experimental techniques. NMR diffusometry offer useful additional possibilities.  In freshly-prepared solutions (without any pre-aggregates of the peptide) diffusion of the peptide can often be described by an unique diffusion kinetics, which corresponds to the calculated diffusion coefficient of the amyloid- b peptide monomers with the Stokes-Einstein hard-sphere approximation (typically D ~10-10 m2/s). In a quasi-equilibrium or in pulse-induced conditions, new larger aggregates of Ab with diffusion coefficients down to <1×10-13 m2/s were detected. 2D 1H NMR NOESY provides both an additional evidence of aggregation and also reveals most probable sites of the side chain interactions in the aggregates. "Pulse-like" treatment of the sample involves: (i) changing of the solution composition; (ii) freezing-thawing; and (iii) sonication of the sample in the course of its incubation. Putative aggregation mechanisms and structures of monomers and oligomers in solutions at different conditions are discussed.1.   Filippov A., Sulejmanova A., Antzutkin O. and Gröbner G. (2005) Diffusion and aggregation of Alzheimer's Abeta(1-40)-peptide in aqueous-TFE solutions as studied by pulsed field gradient NMR. Applied Magnetic Resonance. 29. 439 - 449.2.   Filippov A., Sulejmanova A., Gröbner G. and Antzutkin O. (2008) Effect of freezing on amyloid peptide aggregation and self-diffusion in an aqueous solution. Colloid J. 70. 501-506.3.   Filippov A., Gröbner G. and Antzutkin O. Effect of ultrasonication on amyloid peptide aggregation in trifluoroethanol solution. (in preparation).

  • 230.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Gröbner, Gerhard
    Biological Chemistry, Institute of Chemistry, Umeå University.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Aggregation of amyloid Aβ(1-40) peptide in perdeuterated 2,2,2-trifluoroethanol caused by ultrasound sonication2010In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 48, no 6, p. 427-434Article in journal (Refereed)
    Abstract [en]

    Ultrasound sonication of protein and peptide solutions is routinely used in biochemical, biophysical, pharmaceutical and medical sciences to facilitate and accelerate dissolution of macromolecules in both aqueous and organic solvents. However, the impact of ultrasound waves on folding/unfolding of treated proteins, in particular, on aggregation kinetics of amyloidogenic peptides and proteins is not understood. In this work, effects of ultrasound sonication on the misfolding and aggregation behavior of the Alzheimer's Aβ (1-40)-peptide is studied by pulsed-field gradient (PFG) spin-echo diffusion NMR and UV circular dichroism (CD) spectroscopy. Upon simple dissolution of Aβ(1-40) in perdeuterated trifluoroethanol, CF3-CD2-OD (TFE-d3), the peptide is present in the solution as a stable monomer adopting α-helical secondary structural motifs. The self-diffusion coefficient of Aβ(1 -40) monomers in TFE-d3 was measured as 1.35 × 10-10 m2 s-1, reflecting its monomeric character. However, upon ultrasonic sonication for less than 5 min, considerable populations of Aβ molecules (ca 40%) form large aggregates as reflected in diffusion coefficients smaller than 4.0 × 10-13 m2 s-1. Sonication for longer times (up to 40 min in total) effectively reduces the fraction of these aggregates in 1H PFG NMR spectra to ca 25%. Additionally, absorption below 230 nm increased significantly upon sonication treatment, an observation, which also clearly confirms the ongoing aggregation process of Aβ(1-40) in TFE-d3. Surprisingly, upon ultrasound sonication only small changes in the peptide secondary structure were detected by CD: the peptide molecules mainly adopt α-helical motifs in both monomers and aggregates formed upon sonication.

  • 231.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Khakimov, Aidar
    Kazan (Volga Region) Federal University, Kazan.
    Afonin, Sergii
    Karlsruhe Institute of Technology.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Interaction of prostatic acid phosphatase fragments with a lipid bilayer as studied by NMR spectroscopy2013In: Mendeleev communications (Print), ISSN 0959-9436, E-ISSN 1364-551X, Vol. 23, no 6, p. 313-315Article in journal (Refereed)
    Abstract [en]

    Effects of five fragments of prostatic acid phosphatase on the dimyiristoylphosphatidilcholine lipid multi-lamellar liposomes were studied by 2H and 31P NMR spectroscopy and on planar supported multi-bilayers of the same lipid by 1H and 31P NMR spectroscopy. It was found that hydrophobic interaction is dominated factor of the peptide–membrane binding, while short alpha-helical fragments PAP(262-270) and PAP(262-272) strongly interact to membrane at the interface, generally following to the Gibbs free energy of water-to-interface insertion.

  • 232.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Munavirov, Bulat
    Kazan (Volga Region) Federal University, Kazan.
    Gizatullin, Bulat
    Kazan (Volga Region) Federal University, Kazan.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Disordering of phospholipid headgroups induced by a small amount of polyethylene oxide2013In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 51, no 1, p. 1-3Article in journal (Refereed)
    Abstract [en]

    We present a 31P NMR spectroscopy study of planar glass-plate-oriented multi-bilayers of dimyristoylphosphatidylcholine (DMPC) with addition of polyethylene oxide (PEO). This work revealed the presence of a new component in the spectra that appeared only with addition of a small fraction of PEO (up to one PEO segment per dimyristoylphosphatidylcholine molecule) and disappeared when larger amounts of PEO were added. We explained this phenomenon as an effect of an inhomogeneous force field induced by the PEO molecules located at a certain depth in the lipid membrane interface region

  • 233.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Munavirov, Bulat
    Kazan (Volga Region) Federal University, Kazan.
    Sparrman, Tobias
    Umeå university.
    Ishmuhametova, Valentina
    Kazan (Volga Region) Federal University, Kazan.
    Rudakova, Maya
    Kazan (Volga Region) Federal University, Kazan.
    Shriram, Prashant
    Umeå university.
    Tavelin, Staffan
    Umeå university.
    Interaction of a Poly(acrylic acid) Oligomer with Dimyristoylphosphatidylcholine Bilayers2011In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 7, p. 3754-3761Article in journal (Refereed)
    Abstract [en]

    We studied the influence of 5 kDa poly(acrylic acid) (PAA) on the phase state, thermal properties, and lateral diffusion in bilayered systems of dimyristoylphosphatidylcholine (DMPC) using 31P NMR spectroscopy, differential scanning calorimetry (DSC), 1H NMR with a pulsed field gradient, and 1H nuclear Overhauser enhancement spectroscopy (NOESY). The presence of PAA does not change the lamellar structure of the system. 1H MAS NOESY cross-peaks observed for the interaction between lipid headgroups and polyion protons demonstrated only surface PAA−biomembrane interaction. Small concentrations of PAA (up to 4 mol %) lead to the appearance of a new lateral phase with a higher main transition temperature, a lower cooperativity, and a lower enthalpy of transition. Higher concentrations lead to the disappearance of measurable thermal effects. The lateral diffusion coefficient of DMPC and the apparent activation energy of diffusion gradually decreased at PAA concentrations up to around 4 mol %. The observed effects were explained by the formation of at least two types of PAA−DMPC lateral complexes as has been described earlier (Fujiwara, M.; Grubbs, R. H.; Baldeschwieler, J. D. J. Colloid Interface Sci., 1997, 185, 210). The first one is characterized by a stoichiometry of around 28 lipids per polymer, which corresponds to the adsorption of the entire PAA molecule onto the membrane. Lipid molecules of the complex are exchanged with the “pure” lipid bilayer, with the lifetime of the complex being less than 0.1 s. The second type of DMPC−PAA complex is characterized by a stoichiometry of 6 to 7 lipids per polymer and contains PAA molecules that are only partially adsorbed onto the membrane. A decrease in the DMPC diffusion coefficient and activation energy for diffusion in the presence of PAA was explained by the formation of a new cooperative unit for diffusion, which contains the PAA molecule and several molecules of lipids.

  • 234.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Munavirov, Bulat
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Antzutkin, Oleg
    Institute of Physics, Kazan (Volga Region) Federal University.
    Phase transition, ordering and lateral diffusion in phospholipid bilayers in the presence of poly(ethylene oxide)2012In: Mendeleev communications (Print), ISSN 0959-9436, E-ISSN 1364-551X, Vol. 22, no 5, p. 250-251Article in journal (Refereed)
    Abstract [en]

    The thermal behaviour, molecular orientation and lateral diffusion in the bilayered systems of dimyristoylphosphatidylcholine (DMPC) in the presence of poly(ethylene oxide) (PEO) were studied by NMR and DSC techniques, and it was found that PEO decreases the melting temperature (of vesicles and flat multibilayers) and affects the degree of orientation of DMPC molecules relative to the bilayer normal, but it does not influence the lateral diffusion of DMPC molecules

  • 235.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Munavirov, Bulat
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Gröbner, Gerhard
    Umeå universitet.
    Rudakova, Maya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Lateral diffusion in equimolar mixtures of natural sphingomyelins with dioleoylphosphatidylcholine2012In: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 30, no 3, p. 412-421Article in journal (Refereed)
    Abstract [en]

    Cellular membranes of mammals are composed of a complex assembly of diverse phospholipids. Sphingomyelin (SM) and phosphatidylcholine (PC) are important lipids of eukaryotic cellular membranes and neuronal tissues, and presumably participate in the formation of membrane domains, known as “rafts,” through intermolecular interaction and lateral microphase decomposition. In these two-dimensional membrane systems, lateral diffusion of lipids is an essential dynamic factor, which might even be indicative of lipid phase separation process. Here, we used pulsed field gradient nuclear magnetic resonance to study lateral diffusion of lipid components in macroscopically oriented bilayers composed of equimolar mixtures of natural SMs of egg yolk, bovine brain, bovine milk and dipalmitoylphosphatidylcholine (DPPC) with dioleoylphosphatidylcholine (DOPC). In addition, differential scanning calorimetry was used as a complementary technique to characterize the phase state of the lipid bilayers. In fully liquid bilayers, the lateral diffusion coefficients in both DOPC/DPPC and DOPC/SM systems exhibit mean values of the pure bilayers. For DOPC/SM bilayer system, this behavior can be explained by a model where most SM molecules form short-lived lateral domains with preferential SM–SM interactions occurring within them. However, for bilayers in the presence of their low-temperature gel phase, lateral diffusion becomes complicated and cannot simply be understood solely by a simple change in the liquid phase decomposition.

  • 236.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rudakova, M. A.
    Kazan (Volga Region) Federal University, Kazan.
    Munavirov, B. V.
    Kazan (Volga Region) Federal University, Kazan.
    Lateral diffusion in sphingomyelin bilayers2010In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 48, no 12, p. 945-950Article in journal (Refereed)
    Abstract [en]

    Sphingomyelin (SM) is an important lipid of eukaryotic cellular membranes and neuronal tissues. We studied lateral diffusion in macroscopically oriented bilayers of synthetic palmitoylSM (PSM) and natural sphingomyelins of egg yolk (eSM), bovine brain (bSM) and bovine milk (mSM) by NMR pulsed field gradient (NMR PFG) in the temperature range of 50-60oC. We found that the mean values of lateral diffusion coefficients (LDCs) of SMs are 1.9-fold lower in comparison with dipalmitoylphosphatidylcholine, which is similar in molecular structure. This discrepancy could be explained by the characteristics of intermolecular SM interactions. The LDCs of different SMs differ: egg SM is most similar to PSM, both of them have a 10% higher LDC value in comparison with the two other natural SMs. Besides, all natural SMs show a complicated form of the spin-echo diffusion decay, which is an indicator of a distribution of LDC values in bilayers. This peculiarity was explained by broad distributions of fatty acid lengths of the natural SMs studied here, especially mSM and bSM. We confirmed the relationship between chain length and the LDC in bilayers by computer analysis of a set of 1H NMR spectra obtained by scanning the value of the pulsed field gradient: there is a correlation between lower LDC values and SM molecules with longer acyl chains. The most probable mechanisms by which long-chain SM molecules decrease their lateral diffusion relative to the average value are protrusion into the other side of the bilayer or lateral separation into areas that diverge with their LDCs.

  • 237.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rudakova, Maya
    Kazan (Volga Region) Federal University, Kazan.
    Peculiarities of lateral diffusion of lipids in three-component bilayers2011In: Russian Journal of Physical Chemistry, ISSN 0036-0244, E-ISSN 1531-863X, Vol. 85, no 3, p. 513-518Article in journal (Refereed)
    Abstract [en]

    The lateral diffusion of lipid molecules in macroscopically oriented bilayers of mixed dioleoylphosphatidylcholine (DOPC), egg sphingomyeline (SM), and cholesterol (CHOL) and its dependence on cholesterol concentration and temperature was studied by NMR with pulsed field gradient. The system forms a lamellar liquid crystalline (LC) phase; in a certain range of temperatures and concentrations of cholesterol the system is separated into two subphases: a disordered LC phase (ld) enriched with DOPC, and an ordered phase (l0) enriched with SM. These are characterized by their own lateral diffusion coefficients (LDCs), which differ from one another by a factor of 1.5–5. The dependence of the LDCs in the phases on the cholesterol concentration was analyzed. There was no clear dependence for the disordered LC phase, but we found that LDCs tend to grow in the concentration range of 15–35 mol % of CHOL. This behavior could be due to the redistribution of lipid components as the concentration of CHOL increases, eventually leading to a rise in DOPC concentration in the lo phase. In the range of liquidphase domains, we observed no dependence of LDCs on the diffusion time typical of the restricted diffusion regime, due to spatial restraints in the system. This could be associated with the relatively large size of the domains, and with the domain capability of lateral diffusion in a surrounding continuous phase.

  • 238.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Taher, Mamoun
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Glavatskih, Sergei
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    NMR self-diffusion study of a phosphonium bis(mandelato)borate ionic liquid2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 23, p. 9281-9287Article in journal (Refereed)
    Abstract [en]

    Newly synthesized halogen-free boron based ionic liquids (hf-BILs) composed of chelated orthoborate anionsand phosphonium cations have hydrolytic stability, low melting point and outstanding wear and frictionreducing properties. We report here the peculiarities of self-diffusion in one representative from this class,trihexyltetradecylphosphonium bis(mandelato)borate, [P6,6,6,14][BMB], in the temperature range of itspractical interest, 20–100 1C. NMR techniques demonstrated complicated diffusional behaviour – the ionicliquid can exist in one or two liquid ‘‘phases’’. In the low-temperature range (20–50 1C), two phases coexistwhere the cations, [P6,6,6,14], are contained mainly in the phase with slower diffusion coefficients while theanions, [BMB], are in the phase with faster diffusion coefficients. Cations have lower diffusion coefficientswith a factor of 20 as compared with the anions, an effect which is caused by aggregation of cations intodomains due to so-called ‘‘hydrophobic interaction’’ of their hydrocarbon chains. As the temperature risesabove 60 1C, the two phases merge into one where both ions have equal diffusion coefficients. This iscaused by thermal motion making the cation domains smaller in size and more easily interacting withanions. As a result, anions and cations diffuse in this high-temperature range as a pair.

  • 239.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Skirda, Vladimir
    Kazan (Volga Region) Federal University, Kazan.
    Munavirov, Bulat
    Kazan (Volga Region) Federal University, Kazan.
    Sacharova, Anna
    Kazan (Volga Region) Federal University, Kazan.
    Mobility of molecules and diagram of the state of a glyceryl monooleate–water system according to NMR data2011In: Russian Journal of Physical Chemistry, ISSN 0036-0244, E-ISSN 1531-863X, Vol. 85, no 4, p. 573-583Article in journal (Refereed)
    Abstract [en]

    Transverse relaxation and selfdiffusion of molecules in a glyceryl monooleate (monoolein)–D2O system was studied using pulsed 1H NMR in a range of water concentrations from 10 to 30 wt % and a range of temperatures from 20 to 90°C. It was noted that selfdiffusion is described by one or two selfdiffusion coefficients, depending on the temperature and concentration of water, while NMRrelaxation has a complex form. It was determined that with a reduction in the transverse magnetization, a component that has a form similar to Gaussian and relaxation times of 70 to 250 mcs is observed at certain temperatures and concentrations of water, confirming the formation of structures in which glyceryl monooleate molecules (GM) are characterized by anisotropic rotational mobility. It was demonstrated that the ranges of the concentrations of water and temperature in which this component is observed correspond to liquidcrystalline phase for lamellar and inverse hexagonal structural organizations of lipids, according to the state diagram obtained by X-ray diffraction. In the state diagram fields corresponding to micellar and cubic structures (characterized by the isotropic rotation of GM molecules in the time scale of NMR), multiexponential attenuations of magnetization with average relaxation times were noted in the range of 10 to 200 ms. A number of features were discovered with the use of NMR: specimens always contain structures with isotropic rotational mobility in the presence of structures characterized by anisotropic rotational mobility; a change in the fraction of the structures with anisotropic rotational mobility takes place slowly over 5–15 degrees, not abruptly. Our conclusions regarding the polymorphism of a GM–D2O system in the presence of anisotropic structures was confirmed by an analysis of the transverse NMR relaxation in an egg phosphatidylcholine–D2O system, for which the presence of only lamellar liquidcrystalline structure is recorded in 31P NMR.

  • 240.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Syleymanova, A.
    Gröbner, A.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    NMR study of oligomeric state and molecular mobility of aggregating proteins2008Conference paper (Refereed)
  • 241.
    Forsling, Willis
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Research at the interface between industrial needs and scientific demands2004In: Proceedings, International Seminar on Mineral Processing Technology (MPT-2004): 19 - 21 February 2004 / [ed] G.V. Rao; V.N. Misra, New Delhi: Allied Publishers Ltd , 2004Conference paper (Refereed)
  • 242.
    Forsling, Willis
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Utveckling av aluminiumoxidstabilisering1989Report (Other academic)
  • 243.
    Forsling, Willis
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Vad ska vi göra med kärnkraftsavfallet?2003In: THULE: Kungl. Skytteanska Samfundets Årsbok 2003, Umeå: Kungl. Skytteanska samfundet , 2003, p. 161-172Chapter in book (Other (popular science, discussion, etc.))
  • 244. Forsling, Willis
    et al.
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Betydelsen av grundläggande forskning för mineraltekniska processer2006In: Konferens i mineralteknik / [ed] Marianne Thomaeus; Eric Forssberg, Föreningen Mineralteknisk Forskning / Swedish Mineral Processing Research Association , 2006Conference paper (Other academic)
  • 245.
    Forsling, Willis
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Samskog, Per-Olof
    Research at the interface between industrial needs and scientific demands2005In: Bergsmannen med Jernkontorets Annaler, ISSN 0284-0448, no 3, p. 49-52Article in journal (Other academic)
  • 246.
    Forsling, Willis
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sjöberg, Staffan
    Avdelningen för oorganisk kemi, Umeå universitet.
    Ytkomplexbildning vid sulfidmineralflotation1989In: Konferens i mineralteknik: Luleå 14-16 februari 1989 / [ed] Börje Sköld; Eric Forssberg, MinFo , 1989, p. 83-96Conference paper (Other academic)
  • 247.
    Forsling, Willis
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sterte, Johan
    Skogsindustrin satsar på forskning och utbildning i Luleå: professur i Kemisk Apparatteknik inrättad1997In: Svensk papperstidning, Nordisk cellulosa, ISSN 1101-766X, no 9, p. 49-50Article in journal (Other academic)
  • 248.
    Forsling, Willis
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Su, Fen-Wei
    Luleå tekniska universitet.
    Sun, Zheng-Xi
    Luleå tekniska universitet.
    Samskog, Per-Olof
    LKAB utveckling.
    Forsmo, Seija
    LKAB utveckling.
    Karakterisering av magnetitytor i vattensuspension1994In: Konferens i mineralteknik: Luleå, 2-4 februari 1993 / [ed] Marianne Thomaeus; Eric Forssberg, MinFo , 1994, p. 231-244Conference paper (Other academic)
  • 249.
    Forsling, Willis
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sun, Zhong-Xi
    Luleå tekniska universitet.
    Use of surface complexation models in sulphide mineral flotation1997In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 51, no 1-4, p. 81-95Article in journal (Refereed)
    Abstract [en]

    Surface complexation modelling is introduced to investigate the surface reactions in a mixed galena and sphalerite flotation system. Computer-assisted calculations based on surface complexation modelling (SCM) are performed to obtain the mineral surface distribution of ethyl xanthate as well as carbonate and excess sulphide ions as a function of pH. The significance of pe is demonstrated by computing the mineral surface speciation in a flotation system with xanthate and excess of sulphide ions. The results are used to evaluate the influences of pH, pe, the concentration of xanthate, sulphide or carbonate ions to the mineral flotability. The flotation mechanisms in galena-sphalerite system are discussed based on SCM.

  • 250.
    Forsling, Willis
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Wu, Liuming
    Luleå tekniska universitet.
    Adsorptionsmekanism för organisk tryckare på apatit och kalcit1992In: Konferens i mineralteknik: Luleå, 4-5 februari, 1992 / [ed] Börje Sköld; Eric Forssberg, MinFo , 1992, p. 65-74Conference paper (Other academic)
2345678 201 - 250 of 1343
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