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  • 2701.
    Wren, Joakim
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära. Linköpings universitet, Tekniska högskolan.
    Andersson, P.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära. Linköpings universitet, Tekniska högskolan.
    Radiofrequency Thermal Ablation of Liver Tumors: Impact of Large Vessels2009Ingår i: ASME 2008 Summer Bioengineering Conference: Parts A and B, The American Society of Mechanical Engineers (ASME) , 2009, nr PART B, s. 611-612Konferensbidrag (Refereegranskat)
    Abstract [en]

    Surgical resection is the golden standard for treatment of both primary and metastatic liver tumors, and the method is associated with the highest long-time survival rates [1]. A large number of patients are however not candidates for tumor resection, for example due to un-sufficent hepatic reserve or tumor location relative to large blood vessels. In those cases, an alternative treatment strategy is to heat the tumor(s) to lethal temperatures by means of Radiofrequency (RF) current.

  • 2702.
    Wright, Thomas
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    The linear and nonlinear biomechanics of the middle ear2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis addresses the biomechanics of the human middle ear, that part of the auditory system which converts sound pressure waves in air to fluid pressure waves in the cochlea. The middle ear's mechanism is analysed in four papers, three main and one supporting; in the main papers the middle ear is treated as a multi-particle, multi-rigid body ensemble possessing a variable number of degrees of freedom depending upon the case being investigated.

    It is confirmed, using the standard representation of a single fused incudo-malleal block, that the middle ear's motion is linear, but when this fused block restriction is lifted nonlinearity is present which significantly affects the mechanism's behaviour. In view of the linearity of the chain under the fused block conditions, the explanatory veracity of the conventionally accepted `fixed axis hypothesis' of ossicular motion is examined and found to be wanting as a realistic description of the chain's physical movement.

    The nonlinear behaviour of the ossicular chain centres around the action of the incudo-malleal joint. This joint is shown to have preferential planes of operation, principally the pitch or longitudinal plane and in general to act as an efficient energy dissipator at high driving pressures and low frequencies. Providing the pressure is high enough, it is shown this energy dissipator effect eventually becomes independent of frequency.

    The supporting paper discusses the dynamics of the imposition and removal of equation constraints justifying methods used to investigate the functioning of the incudo-malleal joint.

  • 2703.
    Wu, Yi Ning
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap. School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, China.
    Mattsson, Marie
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Rydberglaboratoriet för tillämpad naturvetenskap (RLAS).
    Ding, Min Wei
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap. School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, China.
    Wu, Meng T.
    School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, China.
    Mei, Juan
    School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, China.
    Shen, Yao Liang
    School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, China.
    Effects of Different Pretreatments on Improving Biogas Production of Macroalgae Fucus Vesiculosus and Fucus Serratus in Baltic Sea2019Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, nr 3, s. 2278-2284Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Global warming along with energy demand and rising prices of natural energy resources have motivated studies to find some renewable and clean energy. The use of algae as the third-generation biofuel can avoid the competition for farmland, and algae can be considered as a potential future source of renewable energy. Algae can be used for biogas production through anaerobic digestion (AD). Fucus vesiculosus and Fucus serratus are the two dominating species of brown seaweed growing in the Baltic Sea in the southwest of Sweden. Pretreatment can significantly affect the biogas production because hydrolysis of the algae cell wall structure is a rate-limiting step in the AD process. In this study, four different pretreatments: mechanical, microwave (600 W, 2 min), ultrasonic (110 V, 15 min), and microwave combined with ultrasonic (600 W, 2 min; 110 V, 15 min) were applied to the seaweed and then codigested with a biogas plant leachate. The aim of this study was to investigate methane yields from AD after these pretreatments. The results showed that when compared with only mechanical pretreatment, the ultrasonic, ultrasonic combined with microwave, and microwave pretreatments could obtain increased cumulative methane yields of 167, 185, and 156%, respectively. The combined pretreatment showed a maximum methane yield of 260 mL/g·of volatile solids after 20 days of digestion. The ultrasonic combined with microwave pretreatment showed a significant improvement in methane yield when compared with the mechanical pretreatment. Copyright © 2019 American Chemical Society

  • 2704.
    Wu, Yu-Tang
    et al.
    Univ Paris 11, Univ Paris Saclay, Inst Integrat Biol Cell, NanoBioPhoton Nanofret Com,CNRS,CEA, Orsay, France..
    Qiu, Xue
    Univ Paris 11, Univ Paris Saclay, Inst Integrat Biol Cell, NanoBioPhoton Nanofret Com,CNRS,CEA, Orsay, France..
    Lindbo, Sarah
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Proteinteknologi.
    Susumu, Kimihiro
    US Naval Res Lab, Opt Sci Div, Code 5600, Washington, DC USA.;KeyW Corp, Hanover, MD 21076 USA..
    Medintz, Igor L.
    US Naval Res Lab, Ctr Bio Mol Sci & Engn, Code 6900, Washington, DC USA..
    Hober, Sophia
    KTH, Skolan för bioteknologi (BIO), Centra, Centrum för Bioprocessteknik, CBioPT. KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Hildebrandt, Niko
    Univ Paris 11, Univ Paris Saclay, Inst Integrat Biol Cell, NanoBioPhoton Nanofret Com,CNRS,CEA, Orsay, France..
    Quantum Dot-Based FRET Immunoassay for HER2 Using Ultrasmall Affinity Proteins2018Ingår i: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 14, nr 35, artikel-id 1802266Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Engineered scaffold affinity proteins are used in many biological applications with the aim of replacing natural antibodies. Although their very small sizes are beneficial for multivalent nanoparticle conjugation and efficient Forster resonance energy transfer (FRET), the application of engineered affinity proteins in such nanobiosensing formats has been largely neglected. Here, it is shown that very small (approximate to 6.5 kDa) histidine-tagged albumin-binding domain-derived affinity proteins (ADAPTs) can efficiently self-assemble to zwitterionic ligand-coated quantum dots (QDs). These ADAPT-QD conjugates are significantly smaller than QD-conjugates based on IgG, Fab', or single-domain antibodies. Immediate applicability by the quantification of the human epidermal growth factor receptor 2 (HER2) in serum-containing samples using time-gated Tb-to-QD FRET detection on the clinical benchtop immunoassay analyzer KRYPTOR is demonstrated here. Limits of detection down to 40 x 10(-12)m (approximate to 8 ng mL(-1)) are in a relevant clinical concentration range and outperform previously tested assays with antibodies, antibody fragments, and nanobodies.

  • 2705.
    Wållberg, Fredrik
    et al.
    KTH, Skolan för bioteknologi (BIO).
    Sundström, Heléne
    KTH, Skolan för bioteknologi (BIO).
    Ledung, E.
    Department of Biology and Chemical Engineering, Mälardalen University.
    Hewitt, C. J.
    Centre for Formulation Engineering, School of Engineering (Chemical Engineering), University of Birmingham.
    Enfors, Sven-Olof
    KTH, Skolan för bioteknologi (BIO).
    Monitoring and quantification of inclusion body formation in Escherichia coli by multi-parameter flow cytometry2005Ingår i: Biotechnology letters, ISSN 0141-5492, E-ISSN 1573-6776, Vol. 27, nr 13, s. 919-926Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multi-parameter flow cytometry was used to monitor the formation of promegapoietin (PMP) inclusion bodies during a high cell density Escherichia coli fed-batch fermentation process. Inclusion bodies were labelled with a primary antibody and then with a secondary fluorescent antibody. Using this method it was possible to detect PMP inclusion body formation with a high specificity and it was possible to monitor the increased accumulation of the protein with process time (6-48 mg PMP/g CDW) whilst highlighting population heterogeneity.

  • 2706.
    Xia, Xin
    et al.
    Nanologica AB, Stockholm, och Dept of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Zhou, Chunfang
    Nanologica AB, Stockholm.
    Ballell, Luís
    Diseases of the Developing World, GlaxoSmithKline, Madrid, Spanien.
    Garcia-Bennett, Alfonso E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    In vivo Enhancement in Bioavailability of Atazanavir in the Presence of Proton-Pump Inhibitors using Mesoporous Materials2012Ingår i: ChemMedChem, ISSN 1860-7179, E-ISSN 1860-7187, Vol. 7, nr 1, s. 43-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Matters of the HAART! The current treatment for human immunodeficiency virus (HIV), HAART, makes use of a combination of antiretroviral drugs, which are poorly soluble in aqueous media. Enhancing the solubility of such drugs through the use of mesoporous materials could lead to improved treatment efficiency and might provide a solution to the drug-drug interaction problems associated with these types of therapeutic regimes.

  • 2707.
    Xiong, S.
    et al.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden.
    Martín, C.
    Umeå University, Department of Chemistry, Umeå, Sweden.
    Eilertsen, L.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden. Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, Umeå, Sweden.
    Wei, M.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden. Guangxi University, College of Agronomy, Nanning, China.
    Myronycheva, Olena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik. Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden.
    Larsson, S.H.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden.
    Lestander, T.A.
    Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, Umeå, Sweden.
    Atterhem, L.
    Biosteam AB, Burträsk, Sweden.
    Jönsson, L.J.
    Umeå University, Department of Chemistry, Umeå, Sweden.
    Energy-efficient substrate pasteurisation for combined production of shiitake mushroom (Lentinula edodes) and bioethanol2019Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 274, s. 65-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hot-air (75 -100°C) pasteurisation (HAP) of birch-wood-based substrate was compared to conventional autoclaving (steam at 121 °C) with regard to shiitake growth and yield, chemical composition of heat-pretreated material and spent mushroom substrate (SMS), enzymatic digestibility of glucan in SMS, and theoretical bioethanol yield. Compared to autoclaving, HAP resulted in faster mycelial growth, earlier fructification, and higher or comparable fruit-body yield. The heat pretreatment methods did not differ regarding the fractions of carbohydrate and lignin in pretreated material and SMS, but HAP typically resulted in lower fractions of extractives. Shiitake cultivation, which reduced the mass fraction of lignin to less than half of the initial without having any major impact on the mass fraction of glucan, enhanced enzymatic hydrolysis of glucan about four-fold. The choice of heating method did not affect enzymatic digestibility. Thus, HAP could substitute autoclaving and facilitate combined shiitake mushroom and bioethanol production.

  • 2708. Xiros, C.
    et al.
    Christakopoulos, Paul
    Biotechnological potential of brewers spent grain and its recent applications2012Ingår i: Waste and Biomass Valorization, ISSN 1877-2641, E-ISSN 1877-265X, Vol. 3, nr 2, s. 213-232Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Brewers spent grain (BSG) is a by-product of the brewing process corresponding to around 85% of total by-products generated. The great number of publications over the last 5 years, on the biotechnological applications of BSG, represents the increased scientific interest on it. This critical, state of the art review aims at gathering and analysing the most recent scientific efforts on the biotechnological potential of Brewer’s spent grain and on its evaluation as a feedstock for high added value products.MethodsThe assiduous bibliographic retrospection focused on the latest scientific reports. The consideration of all relevant scientific articles was thorough and critical. The classification of the scientific efforts was made not only according to the end-products but also according to the biotechnological approach adopted.ResultsBSG has been used in a wide range of biotechnological applications such as substrate for enzymes production, as a source for value-added products (antioxidants, monosaccharides, oligosaccharides, xylitol, arabitol, bioethanol, biogas or lactic acid) or for the production of functional proteins and lipids. Its applications as a carrier in various bioprocesses have also been reported.ConclusionThe implementation of BSG’s fractionation in industrial scale seems to be the next step in BSG’s exploitation. A fractionation process which allows the exploitation of biomolecules belonging to different classes, produced from one feedstock (BSG) may be used as a pattern for the implementation of the biorefinery concept in industrial scale, as long as the methods adopted ensure the functionality of the potentially valuable components.

  • 2709.
    Xiros, Charilaos
    et al.
    National Technical University of Athens, Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Topakas, Evangelos
    National Technical University of Athens, School of Chemical Engineering, National Technical University of Athens, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hydrolysis and Fermentation for Cellulosic Ethanol Production2016Ingår i: Advances in Bioenergy: The Sustainability Challenge, Chichester, UK: John Wiley & Sons Ltd , 2016, s. 11-31Kapitel i bok, del av antologi (Refereegranskat)
  • 2710.
    Xiros, Charilaos
    et al.
    Chalmers University of Technology, Department of Chemical and Biological Engineering.
    Topakas, Evangelos
    BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens.
    Christakopoulos, Paul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hydrolysis and fermentation for cellulosic ethanol production2013Ingår i: Wiley Interdisciplinary Reviews: Energy and Environment, ISSN 2041-8396, E-ISSN 2041-840X, Vol. 2, nr 6, s. 633-654Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Second-generation bioethanol produced from various lignocellulosic materials, such as wood, agricultural, or forest residues, has the potential to be a valuable substitute for, or a complement to, gasoline. At least three major factors—rapidly increasing atmospheric CO2 levels, dwindling fossil fuel reserves, and their rising costs—suggest that we now need to accelerate research plans to make greater use of plant-based biomass for energy production and as a chemical feedstock as part of a sustainable energy economy. Optimizing the production of bioethanol to be competitive with petrochemical fuels is the main challenge for the underlying process development. The exhaustive research on enzyme technology during the latest years, resulting in significant advances in the field, show the importance of the enzymatic hydrolysis for a profitable ethanol production process. On the other hand, the persisting challenges in biomass pretreatment, which are the initial steps in most process designs, show the remarkable recalcitrance of the lignocellulosic materials to biological degradation. The recent scientific trends show toward an integrated overall bioconversion process in which fermentation technology and genetic engineering of ethanologenic microorganisms aim not only at maximizing yields and productivities but also at widening the range of fermentation products and applications.

  • 2711.
    Xiros, Charilaos
    et al.
    National Technical University of Athens.
    Vafiadi, Christina
    National Technical University of Athens.
    Topakas, Evangelos
    National Technical University of Athens.
    Christakopoulos, Paul
    Decrement of cellulose recalcitrance by treatment with ionic liquid (1-ethyl-3-methylimidazolium acetate) as a strategy to enhance enzymatic hydrolysis2012Ingår i: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 87, nr 5, s. 629-634Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: The high crystallinity of cellulose underlies the recalcitrance that this polymer presents in enzymatic degradation. Thus, a pre-treatment step is applied in most bioconversion processes. Treatments with ionic liquids are considered an emerging pre-treatment technology, owing to their high efficiency in solvating cellulose, over molecular solvent systems.RESULTS: Crystalline cellulose with and without ionic liquid (1-ethyl-3-methylimidazolium acetate) treatment, both commercially available, were used as substrates in enzymatic hydrolysis reactions using the earlier evaluated cellulolytic system of Fusarium oxysporum. The in situ removal of the hydrolysate during reactions enhanced the reaction rate as well as the overall glucose production. Ionic liquid treatment significantly decreased cellulose crystallinity and enhanced bioconversion yields and rates. The effects of cellulose structural changes during treatment on hydrolysis rate were investigated and the recalcitrance constants were determined.CONCLUSION: The study showed that ionic liquid-treated cellulose became more homogeneous and more easily degradable than the untreated cellulose, a conclusion that was expressed mathematically by the difference in the recalcitrance constants for the two substrates. It was concluded that glucose production from ionic liquid-treated cellulose could achieve very high conversion yields in consolidated bioprocesses or during simultaneous saccharification and fermentation

  • 2712.
    Xu, Bingze
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för ytbioteknik med Centrum för ytbioteknik.
    Endoglucanase and Mannanase from Blue Mussel, Mytilus edulis: Purification, Characterization, Gene and Three Dimensional Structure2002Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Two polysaccharide-degrading enzymes (endo-1,4-D-glucanase and β-mannanase) from blue mussel, Mytilus edulis, have been purified to homogeneity using a combination of several chromatographic steps. Each enzyme has been characterized with regard to its molecular weight, isoelectric point, pH and temperature stability, pH and temperature optimum and substrate specificity. The amino acid sequence of the endoglucanase has been determined at the protein level. The two enzymes are true blue mussel proteins as confirmed at the DNA level. The nucleotide sequences of synthesized cDNA from digestive gland and of genomic DNA from gill tissue were compared. Both genes contain introns, a property typical of eucaryotic organisms. Amino acid sequence based classification has revealed that the endoglucanase belongs to the glycoside hydrolase family 45, subfamily 2 while β-mannanase is a member of family 5.

    Both enzymes form insoluble inclusion bodies when expressed in Escherichia coli. Refolding attempts were unsuccessful. However, the β-mannanase was successfully expressed in the methylotropic yeast Pichia pastoris with an expression level above 100 mg/l in shaking culture. Crystals of the endoglucanase were made from the native protein and a dataset was collected to 1.85 Å resolution using an in-house rotating anode x-ray source. Crystals were also produced using recombinant β-mannanase and a dataset was collected to 1.4 Å resolution at the ESRF synchrotron beamline ID14-EH1. The three dimensional structure of the endoglucanase was solved by X-ray crystallography.

  • 2713.
    Yang, Jingjing
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Gebremedhin, Alemayehu
    Strand, Michael
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för bygg- och energiteknik (BE).
    Characterization of Particles and Inorganic Vapors through High-Temperature Extraction in a Biomass-Fired Grate Boiler2013Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, nr 10, s. 5915-5922Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, a method for sampling particles and inorganic vapors in hot flue gases was examined in laboratory studies and then applied in field measurements. The method included a hot dilution probe, where the dilution ratio can be controlled. The laboratory results indicated that applied flow rates and dilution ratios can be optimized to produce two distinct particle modes in the particle size distribution: one from the original particles and one from the condensing vapors. The field measurements were performed in a moving grate biomass boiler, and the probe was used for sampling at two positions, at 800 and 1100 degrees C. The size distributions and the size-resolved elemental composition of the samples showed that, at 800 degrees C, alkali sulfates had formed a fine particle mass mode at around 100 nm and that alkali chlorides condensed in the probe to form an additional ultrafine mode in the 10-30 nm range. At 1100 degrees C, a similar bimodal size distribution was obtained as for 800 degrees C; however, the particle diameter of the fine mode was lower and the particle mass concentration was about one-third of the mass at 800 degrees C. The elemental analysis of the ultrafine mode sampled at 1100 degrees C indicated that it was formed mainly from condensing alkali sulfates. In addition, the sample contained detectable amounts of Zn. The suggested interpretation of these results was that, at 1100 degrees C, Zn had oxidized to form ZnO particles and that the formation and condensing of alkali sulfates was in progress, while alkali chlorides were present as vapor.

  • 2714. Yang, Qian
    et al.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Ahmed, Sheikh Ali
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Dimensional stability and water repellency of european aspen improved by oxidized carbohydrates2013Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, nr 1, s. 487-498Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Small samples from European aspen (Populus tremula L.) were impregnated with carbohydrates oxidized by Fenton’s reagent using water in a vacuum, followed by heating in an oven at 103°C. An antiswelling efficiency (ASE) of around 45% for wood treated with oxidized glucose and 35% for wood treated with oxidized sucrose was obtained. Samples treated with oxidized carbohydrates gave water repellent effectiveness (WRE) values over 35%. The decrease in cell wall thickness during impregnation was about 18% less in the presence of oxidized glucose than samples only treated with Fenton’s reagent. An ASE of 20% for the wood samples that had been treated with oxidized glucose was obtained after 7 days of soaking in water. The reasons for the improvement in dimensional stability are discussed in this work.

  • 2715.
    Yang, Xifeng
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Fu, Kai
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Fu, Ying
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Strain effect in determining the geometric shape of self-assembled quantum dot2009Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 42, nr 125414Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The geometric shape of a self-assembled quantum dot (QD) formed by the strain-induced Stranski-Krastanov mode has been studied as a function of strain energy by the short-range valence-force-field approach. It has been shown by dynamic bond relaxation through strain energy minimization that for the most commonly used InAs QD in GaAs and InP matrices and Ge QD in Si matrix, a pyramidal shape is energy favoured over an hemispherical shape when the QD is not capped due to the lattice relaxation at the QD surface. When the QD becomes totally embedded in the background material, the elastic strain energy of a hemispherical InAs QD is minimal. The results agree with experimental observations. We further studied the coupling of strain fields of QDs in adjacent QD layers which shows that QDs in multiply stacked QD layers can be aligned along the layer growth direction in order to minimize the strain energy.

  • 2716. Yanti, Heri
    et al.
    Wikandari, Rachma
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Millati, Ria
    Niklasson, Claes
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Effect of ester compounds on biogas production: beneficial or detrimental?2014Ingår i: Energy Science & Engineering, Vol. 2, nr 1, s. 22-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Esters are major flavor compounds in fruits, which are produced in high volume. The widespread availability of these compounds in nature attracts interest on their behavior in anaerobic digestion in waste and wastewater treatments. The aim of this work was to study the effects of various esters at different concentrations in anaerobic digestion followed by determination of their minimum inhibitory concentration (MIC), and to study the effect of chain length of functional group and alkyl chain of ester on methane production. Addition of methyl butanoate, ethyl butanoate, ethyl hexanoate, and hexyl acetate at concentration up to 5 g L−1 increased methane production, while their higher concentrations inhibited the digestion process. The MIC values for these esters were between 5 and 20 g L−1. Except hexyl acetate, the esters at concentration 5 g L−1 could act as sole carbon source during digestion. For ethyl esters, increasing number of carbon in functional group decreased methane production. For acetate esters, alkyl chain longer than butyl inhibited methane production. Effect of ester on methane production is concentration-dependent.

  • 2717. Yazdani, Parviz
    et al.
    Zamani, Akram
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Karimi, Keikhosro
    Taherzadeh, Mohammad J
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Characterization of Nizimuddinia zanardini macroalgae biomass composition and its potential for biofuel production.2015Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 176, s. 196-202Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nizimuddinia zanardini macroalgae, harvested from Persian Gulf, was chem. characterized and employed for the prodn. of ethanol, seaweed ext., alginic acid, and biogas. In order to improve the products yields, the biomass was pretreated with dil. sulfuric acid and hot water. The pretreated and untreated biomasses were subjected to enzymic hydrolysis by cellulase (15 FPU/g) and β-glucosidase (30 IU/g). Hydrolysis yield of glucan was 29.8, 82.5, and 72.7 g/kg for the untreated, hot-water pretreated, and acid pretreated biomass, resp. Anaerobic fermn. of hydrolyzates by Saccharomycescerevisiae resulted in the max. ethanol yield of 34.6 g/kg of the dried biomass. A seaweed ext. contg. mannitol and a solid residue contg. alginic acid were recovered as the main byproducts of the ethanol prodn. On the other hand, the biogas yield from the biomass was increased from 170 to 200 m3 per ton of dried algae biomass by hot water pretreatment. [on SciFinder(R)]

  • 2718.
    Yedur, Sanjay K
    et al.
    Michigan State University.
    Berglund, Kris
    Use of fluorescence spectroscopy in concentration and supersaturation measurements in citric acid solutions1996Ingår i: Applied Spectroscopy, ISSN 0003-7028, E-ISSN 1943-3530, Vol. 50, nr 7, s. 866-870Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Measurement of supersaturation is of critical importance in the operation and control of crystallizers. In this work, we report a novel spectroscopic technique to achieve the measurement of concentration and supersaturation in crystallizing solutions. In order to develop a sensor for this measurement, citric acid is chosen as the model solute, and the analytical technique involves fluorescence spectroscopy. Citric acid is a common food-grade compound with a wide range of applications that is exclusively produced by crystallization. The fluorescent properties of a probe, 8-hydroxy-1,3,6-pyrenetrisulfonate (pyranine), are used to provide concentration measurements in aqueous citric acid solutions, thereby providing for supersaturation estimation. The change in the relative emission peak intensities of the probe in different solute concentrations gives an excellent calibration curve for concentration measurements. It is also shown that, although pyranine responds to both its solvent microenvironment and the pH of the solution, it is still possible to measure concentration and supersaturation by using this fluorescence technique.

  • 2719.
    Yedur, Sanjay K.
    et al.
    Michigan State University.
    Dulebohn, Joel
    Grand River Technologies, Lansing, MI.
    Werpy, Todd
    Michigan Biotechnology Institute, Lansing.
    Berglund, Kris
    Synthesis and testing of catalysts for the production of maleic anhydride from a fermentation feedstock1996Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 35, nr 3, s. 663-671Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is necessary to develop alternate pathways for the production of chemicals that are traditionally produced from fossil fuels to reduce our dependency on nonrenewable energy sources. In this paper, an alternate technology is presented for producing maleic anhydride from a fermentation feedstock. The process involves the catalytic oxydehydrogenation of fermentation-derived succinic anhydride to produce maleic anhydride. Various catalysts have been synthesized and tested for the oxydehydrogenation reaction. Iron phosphate based catalysts are found to be the best on the basis of high conversions and selectivities obtained. The effects of temperature, oxygen concentration, contact time, and the total time on stream on the performance of the catalyst are investigated, and an optimum set of conditions for the operation of the bench-scale reactor is presented. The bulk and surface compositions, the surface areas, and the bulk crystallographic structure of the catalysts are also reported.

  • 2720.
    Ying, Zhang
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    A new generation density functional towards chemical accuracy2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Density functional theory (DFT) has become the leading method in calculating theelectronic structures and properties from first principles. In practical applicationsof DFT in the frame work of Kohn-Sham (KS) method, an approximate exchange-correlation functional has to be chosen. Hence, the success of a DFT calculationcritically depends on the quality of the exchange-correlation functional.This thesis focuses on the development and validation of the so-called dou-bly hybrid density functionals (DHDFs). DHDFs present a new generation offunctionals, which not only have a non-local orbital-dependent component in theexchange part, but also incorporate the information of unoccupied orbitals in thecorrelation part. I will first give an overview of modern DFT in the introductorychapters, emphasizing the theoretical bases of a newly developed DHDF, XYG3.I will then present further examination of XYG3 and new development on top ofXYG3, leading to XYG3o and XYG3s. Attempts have also been made to extractband structure information of a periodic system from cluster model calculations.

  • 2721.
    Ylitervo, P.
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Franzen, C.J.
    Taherzadeh, M.J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Continuous ethanol production with a membrane bioreactor at high acetic Acid concentrations2014Ingår i: Membranes, ISSN 2077-0375, E-ISSN 2077-0375, Vol. 4, nr 3, s. 372-387Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The release of inhibitory concentrations of acetic acid from lignocellulosic raw materials during hydrolysis is one of the main concerns for 2nd generation ethanol production. The undissociated form of acetic acid can enter the cell by diffusion through the plasma membrane and trigger several toxic effects, such as uncoupling and lowered intracellular pH. The effect of acetic acid on the ethanol production was investigated in continuous cultivations by adding medium containing 2.5 to 20.0 g·L−1 acetic acid at pH 5.0, at a dilution rate of 0.5 h−1. The cultivations were performed at both high (~25 g·L−1) and very high (100–200 g·L−1) yeast concentration by retaining the yeast cells inside the reactor by a cross-flow membrane in a membrane bioreactor. The yeast was able to steadily produce ethanol from 25 g·L−1 sucrose, at volumetric rates of 5–6 g·L−1·h−1 at acetic acid concentrations up to 15.0 g·L−1. However, the yeast continued to produce ethanol also at a concentration of 20 g·L−1 acetic acid but at a declining rate. The study thereby demonstrates the great potential of the membrane bioreactor for improving the robustness of the ethanol production based on lignocellulosic raw materials.

  • 2722.
    Ylitervo, Päivi
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Concepts for improving ethanol productivity from lignocellulosic materials: encapsulated yeast and membrane bioreactors2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Lignocellulosic biomass is a potential feedstock for production of sugars, which can be fermented into ethanol. The work presented in this thesis proposes some solutions to overcome problems with suboptimal process performance due to elevated cultivation temperatures and inhibitors present during ethanol production from lignocellulosic materials. In particular, continuous processes operated at high dilution rates with high sugar utilisation are attractive for ethanol fermentation, as this can result in higher ethanol productivity. Both encapsulation and membrane bioreactors were studied and developed to achieve rapid fermentation at high yeast cell density. My studies showed that encapsulated yeast is more thermotolerant than suspended yeast. The encapsulated yeast could successfully ferment all glucose during five consecutive batches, 12 h each at 42 °C. In contrast, freely suspended yeast was inactivated already in the second or third batch. One problem with encapsulation is, however, the mechanical robustness of the capsule membrane. If the capsules are exposed to e.g. high shear forces, the capsule membrane may break. Therefore, a method was developed to produce more robust capsules by treating alginate-chitosan-alginate (ACA) capsules with 3-aminopropyltriethoxysilane (APTES) to get polysiloxane-ACA capsules. Of the ACA-capsules treated with 1.5% APTES, only 0–2% of the capsules broke, while 25% of the untreated capsules ruptured within 6 h in a shear test. In this thesis membrane bioreactors (MBR), using either a cross-flow or a submerged membrane, could successfully be applied to retain the yeast inside the reactor. The cross-flow membrane was operated at a dilution rate of 0.5 h-1 whereas the submerged membrane was tested at several dilution rates, from 0.2 up to 0.8 h-1. Cultivations at high cell densities demonstrated an efficient in situ detoxification of very high furfural levels of up to 17 g L-1 in the feed medium when using a MBR. The maximum yeast density achieved in the MBR was more than 200 g L-1. Additionally, ethanol fermentation of nondetoxified spruce hydrolysate was possible at a high feeding rate of 0.8 h-1 by applying a submerged membrane bioreactor, resulting in ethanol productivities of up to 8 g L-1 h-1. In conclusion, this study suggests methods for rapid continuous ethanol production even at stressful elevated cultivation temperatures or inhibitory conditions by using encapsulation or membrane bioreactors and high cell density cultivations.

  • 2723.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Akinbomi, J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Taherzadeh, M.J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Membrane bioreactors’ potential for ethanol and biogas production: A review2013Ingår i: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 34, nr 13-14, s. 1711-1723Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Companies developing and producing membranes for different separation purposes, as well as the market for these, have markedly increased in numbers over the last decade. Membrane and separation technology might well contribute to making fuel ethanol and biogas production from lignocellulosic materials more economically viable and productive. Combining biological processes with membrane separation techniques in a membrane bioreactor (MBR) increases cell concentrations extensively in the bioreactor. Such a combination furthermore reduces product inhibition during the biological process, increases product concentration and productivity, and simplifies the separation of product and/or cells. Various MBRs have been studied over the years, where the membrane is either submerged inside the liquid to be filtered, or placed in an external loop outside the bioreactor. All configurations have advantages and drawbacks, as reviewed in this paper. The current review presents an account of the membrane separation technologies, and the research performed on MBRs, focusing on ethanol and biogas production. The advantages and potentials of the technology are elucidated.

  • 2724.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Barghi, Hamidreza
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Franzén, Carl Johan
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Improving the stability and mechanical resistance of capsules for encapsulation of S. cerevisiae2010Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Nowadays, fuel ethanol is both used as a substitute and an additive to the conventional fossil fuels and the interest in converting lignocellulose to fuel ethanol has expanded in the last few decades. Lignocellulose is attractive as raw material due to its high abundance and low price. However, chemical hydrolysis or pre-treatment of lignocelluloses creates several components that are toxic to fermenting organisms and makes cultivation complicated. By using encapsulated yeast, one can overcome this problem. In encapsulation, the yeast cells are confined inside a capsule composed of an outer semi-permeable membrane and an inner liquid core (Fig. 1). Encapsulation is an attractive method since it can improve the cell stability and inhibitor tolerance, increase the biomass concentration, and decrease the cost of cell recovery, recycling, downstream processing, and fermentation time. Mechanical resistance is a key parameter together with permeability for the success of an encapsulation system. In order to improve the robustness of the capsules we are testing different cross linkers to introduce covalent bonds to the chitosan-alginate matrix. By treating chitosan covered alginate capsules with glutaraldehyde the capsules became harder and less elastic. One big disadvantage in using crosslinking agent is, however, that they are toxic for the yeast. If the encapsulated yeast is treated at too harsh conditions they will die. Although, to improve the capsules mechanical strength the membrane have to be crosslinked to a satisfying degree. We have examined different capsule-treatments and found some encouraging results when applying repetitive treatments with crosslinking agent.

  • 2725.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Doyen, Win
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Fermentation of lignocellulosic hydrolyzate using a submerged membrane bioreactor at high dilution rates2014Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A submerged membrane bioreactor (sMBR) was developed to ferment toxic lignocellulosic hydrolyzate to ethanol. The sMBR achieved high cell density of Saccharomyces cerevisiae during continuous cultivation of the hydrolyzate by completely retaining all yeast cells inside the sMBR. The performance of the sMBR was evaluated based on the ethanol yield and productivity at the dilution rates 0.2, 0.4, 0.6, and 0.8 h-1 with the increase of dilution rate. Results show that the yeast in the sMBR was able to ferment the wood hydrolyzate even at high dilution rates, attaining a maximum volumetric ethanol productivity of 7.94 ± 0.10 g L-1 h-1 at a dilution rate of 0.8 h-1. Ethanol yields were stable at 0.44 ± 0.02 g g-1 during all the tested dilution rates, and the ethanol productivity increased from 2.16 ± 0.15 to 7.94 ± 0.10 g L-1 h-1. The developed sMBR systems running at high yeast density demonstrates a potential for a rapid and productive ethanol production from wood hydrolyzate.

  • 2726. Ylitervo, Päivi
    et al.
    Franzen, Carl Johan
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol production at elevated temperatures using encapsulation of yeast2011Ingår i: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 156, nr 1, s. 22-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ability of macroencapsulated Saccharomyces cerevisiae CBS 8066 to produce previous termethanolnext term at previous termelevatednext termprevious termtemperaturesnext term was investigated in consecutive batch and continuous cultures. Prior to cultivation previous termyeastnext term was confined inside alginate–chitosan capsules composed of an outer semi-permeable membrane and an inner liquid core. The encapsulated previous termyeastnext term could successfully ferment 30 g/L glucose and produce previous termethanolnext term at a high yield in five consecutive batches of 12 h duration at 42 °C, while freely suspended previous termyeastnext term was completely inactive already in the third batch. A high previous termethanolnext termprevious termproductionnext term was observed also through the first 48 h at 40 °C during continuous cultivation at D = 0.2 h−1 when using encapsulated cells. The previous termethanolnext termprevious termproductionnext term slowly decreased in the following days at 40 °C. The previous termethanolnext termprevious termproductionnext term was also measured in a continuous cultivation in which the previous termtemperaturenext term was periodically increased to 42–45 °C and lowered to 37 °C again in periods of 12 h. Our investigation shows that a non-thermotolerant previous termyeastnext term strain improved its heat tolerance upon previous termencapsulationnext term, and could produce previous termethanolnext term at previous termtemperaturesnext term as high as 45 °C for a short time. The possibility of performing fermentations at higher previous termtemperaturesnext term would greatly improve the enzymatic hydrolysis in simultaneous saccharification and fermentation (SSF) processes and thereby make the bioethanol previous termproductionnext term process more economically feasible.

  • 2727.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Franzen, CJ
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ethanol production from lignocellulosic raw materials by encapsulated Saccharomyces cerevisiae2009Konferensbidrag (Övrigt vetenskapligt)
  • 2728.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Franzén, Carl Johan
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Impact of Furfural on Rapid Ethanol Production Using a Membrane Bioreactor2013Ingår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 6, nr 3, s. 1604-1617Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abstract: A membrane bioreactor was developed to counteract the inhibition effect of furfural in ethanol production. Furfural, a major inhibitor in lignocellulosic hydrolyzates, is a highly toxic substance which is formed from pentose sugars released during the acidic degradation of lignocellulosic materials. Continuous cultivations with complete cell retention were performed at a high dilution rate of 0.5 h−1. Furfural was added directly into the bioreactor by pulse injection or by addition into the feed medium to obtain furfural concentrations ranging from 0.1 to 21.8 g L−1. At all pulse injections of furfural, the yeast was able to convert the furfural very rapidly by in situ detoxification. When injecting 21.8 g L−1 furfural to the cultivation, the yeast converted it by a specific conversion rate of 0.35 g g−1 h−1. At high cell density, Saccharomyces cerevisiae could tolerate very high furfural levels without major changes in the ethanol production. During the continuous cultures when up to 17.0 g L−1 furfural was added to the inlet medium, the yeast successfully produced ethanol, whereas an increase of furfural to 18.6 and 20.6 g L−1 resulted in a rapidly decreasing ethanol production and accumulation of sugars in the permeate. This study show that continuous ethanol fermentations by total cell retention in a membrane bioreactor has a high furfural tolerance and can conduct rapid in situ detoxification of medium containing high furfural concentrations.

  • 2729.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Franzén, Carl Johan
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Mechanically robust polysiloxane: ACA capsules for prolonged ethanol production2013Ingår i: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 88, nr 6, s. 1080-1088Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fermentation using encapsulated yeast leads to more robust ethanol production from lignocellulose hydrolyzates. Encapsulated yeast is much more tolerant to inhibitors present in hydrolyzates, and fermentation is faster due to increased total cell density. For industrial applications, capsules must be made robust enough to endure long periods and numerous cultivations without breaking. Liquid core alginate–chitosan–alginate (ACA) capsules containing Saccharomyces cerevisiae were produced by the liquid-droplet-forming method and treated with hydrolyzed 3-aminopropyltrietoxysilane (hAPTES) forming very glossy capsules. Capsules produced with 3.0% hAPTES showed the best mechanical robustness but no ethanol could be produced in dilute-acid spruce hydrolyzate using these capsules. Untreated ACA capsules gave the highest ethanol production but demonstrated poor mechanical robustness. 25% of the ACA capsules ruptured within 6 h in the shear test. Capsules treated with 1.5% hAPTES were significantly stronger, since only 0–2% of these capsules broke. Moreover, the ethanol production in the fifth consecutive cultivation in lignocellulose hydrolyzate was nearly as high as for untreated ACA capsules. The mechanical robustness of ACA capsules can be easily improved by treating the capsules with hAPTES. ACA capsules treated with 1.5% hAPTES showed excellent mechanical robustness and a similar ethanol production profile to untreated ACA capsules. © 2012 Society of Chemical Industry

  • 2730.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Franzén, Carl Johan
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Robust liquid core APTES-alginate-chitosan-alginate capsules for 2nd generation bioethanol production2012Konferensbidrag (Övrigt vetenskapligt)
  • 2731.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Franzén, Carl Johan
    Taherzadeh, Mohammad
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Robust polysiloxane-ACA capsules for ethanol production from wood hydrolyzate by yeast2012Konferensbidrag (Övrigt vetenskapligt)
  • 2732.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Franzén, Carl Johan
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Continuous Ethanol Production with a Membrane Bioreactor at High Acetic Acid Concentrations2014Ingår i: Membranes, ISSN 2077-0375, E-ISSN 2077-0375, Vol. 4, nr 3, s. 372-387Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The release of inhibitory concentrations of acetic acid from lignocellulosic raw materials during hydrolysis is one of the main concerns for 2nd generation ethanol production. The undissociated form of acetic acid can enter the cell by diffusion through the plasma membrane and trigger several toxic effects, such as uncoupling and lowered intracellular pH. The effect of acetic acid on the ethanol production was investigated in continuous cultivations by adding medium containing 2.5 to 20.0 g•L−1 acetic acid at pH 5.0, at a dilution rate of 0.5 h−1. The cultivations were performed at both high (~25 g•L−1) and very high (100–200 g•L−1) yeast concentration by retaining the yeast cells inside the reactor by a cross-flow membrane in a membrane bioreactor. The yeast was able to steadily produce ethanol from 25 g•L−1 sucrose, at volumetric rates of 5–6 g•L−1•h−1 at acetic acid concentrations up to 15.0 g•L−1. However, the yeast continued to produce ethanol also at a concentration of 20 g•L−1 acetic acid but at a declining rate. The study thereby demonstrates the great potential of the membrane bioreactor for improving the robustness of the ethanol production based on lignocellulosic raw materials.

  • 2733.
    Ylitervo, Päivi
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Franzén, CJ.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Increasing the thermotolerance of Saccharomyces cerevisiae by encapsulation2010Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Encapsulated yeast has several advantages for ethanol production from lignocellulosic materials such as enhanced inhibitor tolerance and cell stability, higher biomass concentration inside the reactor, easier cell recovery and shortened fermentation time (Talebnia 2005). During encapsulation, cells are captured inside a spherical capsule composed of an outer semipermeable membrane and an inner liquid core. Compared to entrapment in a porous gel bead, the diffusion resistance is therefore much lower trough the capsule membrane (Talebnia 2005). Encapsulation has in several studies shown to stabilize cells and improve the tolerance for inhibitors (Talebnia 2005, Pourbafrani 2008). The main goal of the present work was to investigate if encapsulation can also improve the termotolerance characteristics of S. cerevisiae in order to produce ethanol at high temperatures. In the experiments glucose conversion and ethanol production was recorded during 24 h in encapsulated and suspended yeast at high temperatures.

  • 2734.
    Yoon, Kukjin
    et al.
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Takahashi, Shiho
    Forestry and Forest Products Research Institute, Tsukuba, Ibaraki.
    Nge, Thi Thi
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi. Forestry and Forest Products Laboratory, Tsukuba, Ibaraki.
    Nakagawa-izumi, Akiko
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Ohi, Hiroshi
    Graduate School of Life and Environmental Sciences, University of Tsukuba.
    Uraki, Yasumitsu
    Faculty of Agriculture, Hokkaido University, Sapporo.
    Yamada, Tatsuhiko
    Graduate School of Life and Environmental Sciences, University of Tsukuba, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki.
    Thermal Melting of Lignin Derivates Prepared from Dried Black Liquor Powder of Softwood Soda-AQ Cooking and Polyehylene Glycol2015Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, nr 1, s. 912-921Artikel i tidskrift (Refereegranskat)
  • 2735.
    Youngsukkasem, S.
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Akinbomi, J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Rakshit, S.K.
    Taherzadeh, M.J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Biogas production by encased bacteria in synthetic membranes: Protective effects in toxic media and high loading rates2013Ingår i: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 34, nr 13-14, s. 2077-2084Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A bioreactor including encased digesting bacteria for biogas production was developed, and its performance in toxic media and under high organic loading rates (OLRs) was examined and compared with traditional digestion reactors. The bacteria (3 g) were encased and sealed in 3 × 6cm 2 PVDF (polyvinylidene fluoride) membranes with a pore size of 0.1 μ m, and then several sachets were placed in the reactors. They were then examined in toxic medium containing up to 3% limonene as a model inhibitor in batch reactors, and OLRs of up to 20 g COD / L.day in semi-continuous digestions. The free and encased cells with an identical total bacterial concentration of 9 g in a medium containing 2% limonene produced at most 6.56 and 23.06 mL biogas per day, respectively. In addition, the digestion with free cells completely failed at an OLR of 7.5 g COD / L.day, while the encased cells were still fully active with a loading of 15 g COD / L.day.

  • 2736.
    Youngsukkasem, Supansa
    et al.
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Chandolias, Konstantinos
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Taherzadeh, Mohammad J
    Högskolan i Borås.
    Rapid bio-methanation of syngas in a reverse membrane bioreactor: membrane encased microorganisms2015Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 178, s. 334-40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The performance of a novel reverse membrane bioreactor (RMBR) with encased microorganisms for syngas bio-methanation as well as a co-digestion process of syngas and organic substances was examined. The sachets were placed in the reactors and examined in repeated batch mode. Different temperatures and short retention time were studied. The digesting sludge encased in the PVDF membranes was able to convert syngas into methane at a retention time of 1 day and displayed a similar performance as the free cells in batch fermentation. The co-digestion of syngas and organic substances by the RMBR (the encased cells) showed a good performance without any observed negative effects. At thermophilic conditions, there was a higher conversion of pure syngas and co-digestion using the encased cells compared to at mesophilic conditions.[on SciFinder (R)]

  • 2737. Youngsukkasem, Supansa
    et al.
    Rakshit, Sudip K.
    Taherzadeh, Mohammad J.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Biogas production by encapsulated digesting bacteria2012Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, nr 1, s. 56-65Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Encapsulation of methane producing bacteria was performed to enhance the rate of biogas production, using natural as well as synthetic membranes. A one-step liquid-droplet-forming method was employed for the natural membrane, resulting in spherical capsules with an average diameter and a membrane thickness of 4.3 and 0.2 mm, respectively. The capsules were made from alginate, with chitosan or Ca2+ as counter-ions, with addition of carboxymethylcellulose (CMC). For synthetic capsules, the Durapore® membrane (hydrophilic PVDF), with a pore size of 0.1 µm, was used for capsules of the sizes 3×3 and 3×6 cm, holding the bacteria. During the digesting process the dissolved substrates penetrated through the capsule membranes, and biogas developed inside the capsules, escaping by diffusion. The results indicate that encapsulation is a promising method of digestion, with a high density of anaerobic bacteria. The method holds a considerable potential for further development of membranes and their applications.

  • 2738. Yu, Fang Fang
    et al.
    Lin, Xia Lu
    Yang, Lei
    Liu, Huan
    Wang, Xi
    Fang, Hua
    Lammi, Mikko J.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Institute of Endemic Diseases, School of Public Health of Health Science Center, Xi’an Jiaotong University, Key Laboratory of Trace Elements and Endemic Diseases, National Health and Family Planning Commission, Xi’an 710061, Shaanxi, China.
    Guo, Xiong
    Comparison of T-2 Toxin and HT-2 Toxin Distributed in the Skeletal System with That in Other Tissues of Rats by Acute Toxicity Test2017Ingår i: Biomedical and environmental sciences, ISSN 0895-3988, E-ISSN 2214-0190, Vol. 30, nr 11, s. 851-854Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Twelve healthy rats were divided into the T-2 toxin group receiving gavage of 1 mg/kg T-2 toxin and the control group receiving gavage of normal saline. Total relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system (thighbone, knee joints, and costal cartilage) were significantly higher than those in the heart, liver, and kidneys (P < 0.05). The relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system (thighbone and costal cartilage) were also significantly higher than those in the heart, liver, and kidneys. The rats administered T-2 toxin showed rapid metabolism compared with that in rats administered HT-2 toxin, and the metabolic conversion rates in the different tissues were 68.20%-90.70%.

  • 2739. Yu, Meijuan
    et al.
    Yang, Feifei
    Chu, Wangsheng
    Wang, Yu
    Zhao, Haifeng
    Gao, Bin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Zhao, Wei
    Sun, Jianping
    Wu, Fangming
    Zhang, Xiaowei
    Shi, Yunyu
    Wu, Ziyu
    3D local structure around Zn in Kti11p as a representative Zn-(Cys)4 motif as obtained by MXAN2008Ingår i: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 374, nr 1, s. 28-32Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Zinc is an important component of many proteins that play key roles in transcription, translation, and catalysis. Kti11p, DESR1, both belonging to a protein family characterized by a CSL zinc finger domain, and the co-catalytic zinc-protein PML containing a Zn2+ binding domain called RING or C3HC4 finger are all structurally determined by NMR although the zinc sites are silent to this spectroscopical method. The comparison of X-ray absorption near-edge spectroscopy (XANES) data for the three proteins demonstrates that fingerprints effect is a reliable method for a primary characterization of ligand species. Ab initio full MS Calculations performed by MAN are applied to obtain chemical and stereo structural information around the Zn ion in Kti11p. For the first time this high-spatial resolution technique confirms the formation of a stable Zn tetrahedral configuration with four sulfur ligands, and returns extremely accurate bond angle information between ligands.

  • 2740.
    Yu, Shengze
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap.
    Alkharusi, Amira
    Sultan Qaboos Univ, Coll Med & Hlth Sci, Muscat, Oman..
    Norstedt, Gunnar
    Sultan Qaboos Univ, Coll Med & Hlth Sci, Muscat, Oman.;Karolinska Inst, Ctr Mol Med, Stockholm, Sweden..
    Gräslund, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap.
    An in vivo half-life extended prolactin receptor antagonist can prevent STAT5 phosphorylation2019Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 14, nr 5, artikel-id e0215831Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increasing evidence suggests that signaling through the prolactin/prolactin receptor axis is important for stimulation the growth of many cancers including glioblastoma multiforme, breast and ovarian carcinoma. Efficient inhibitors of signaling have previously been developed but their applicability as cancer drugs is limited by the short in vivo half-life. In this study, we show that a fusion protein, consisting of the prolactin receptor antagonist PrlRA and an albumin binding domain for half-life extension can be expressed as inclusion bodies in Escherichia coli and efficiently refolded and purified to homogeneity. The fusion protein was found to have strong affinity for the two intended targets: the prolactin receptor (K-D = 2.3 +/- 0.2 nM) and mouse serum albumin (K-D = 0.38 +/- 0.01 nM). Further investigation showed that it could efficiently prevent prolactin mediated phosphorylation of STAT5 at 100 nM concentration and above, similar to the PrlRA itself, suggesting a potential as drug for cancer therapy in the future. Complexion with HSA weakened the affinity for the receptor to 21 +/- 3 nM, however the ability to prevent phosphorylation of STAT5 was still prominent. Injection into rats showed a 100-fold higher concentration in blood after 24 h compared to PrlRA itself.

  • 2741. Yu, Tao
    et al.
    Zhou, Yongjin J.
    Wenning, Leonie
    Liu, Quanli
    Krivoruchko, Anastasia
    Siewers, Verena
    Nielsen, Jens
    KTH, Skolan för bioteknologi (BIO), Genteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab. Chalmers University of Technology, Sweden.
    David, Florian
    Metabolic engineering of Saccharomyces cerevisiae for production of very long chain fatty acid-derived chemicals2017Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, artikel-id 15587Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Production of chemicals and biofuels through microbial fermentation is an economical and sustainable alternative for traditional chemical synthesis. Here we present the construction of a Saccharomyces cerevisiae platform strain for high-level production of very-long-chain fatty acid (VLCFA)-derived chemicals. Through rewiring the native fatty acid elongation system and implementing a heterologous Mycobacteria FAS I system, we establish an increased biosynthesis of VLCFAs in S. cerevisiae. VLCFAs can be selectively modified towards the fatty alcohol docosanol (C22H46O) by expressing a specific fatty acid reductase. Expression of this enzyme is shown to impair cell growth due to consumption of VLCFA-CoAs. We therefore implement a dynamic control strategy for separating cell growth from docosanol production. We successfully establish high-level and selective docosanol production of 83.5 mg l(-1) in yeast. This approach will provide a universal strategy towards the production of similar high value chemicals in a more scalable, stable and sustainable manner.

  • 2742.
    Yuan, Zhaoyang
    et al.
    Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, United States.
    Singh, Sandip Kumar
    Department of Chemical & Biological Engineering, Montana State University, Montana, United States.
    Bals, Bryan
    Michigan Biotechnology Institute, Lansing, Michigan, United States.
    Hodge, David B.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. Department of Chemical & Biological Engineering, Montana State University, Bozeman, Montana , United States.
    Hegg, Eric L.
    Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, United States.
    Integrated Two-Stage Alkaline–Oxidative Pretreatment of Hybrid Poplar. Part 2: Impact of Cu-Catalyzed Alkaline Hydrogen Peroxide Pretreatment Conditions on Process Performance and Economics2019Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 58, nr 35, s. 16000-16008Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two-stage alkaline/copper 2,2′-bipyridine-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment is an effective strategy for improving the enzymatic digestibility of hybrid poplar. To reduce the chemical inputs and processing costs associated with this process, we investigated the effect of increasing the temperature for both the alkaline pre-extraction and the Cu-AHP pretreatment stages. The results indicate that increasing the alkaline pre-extraction and the Cu-AHP pretreatment temperatures from 30 to 120 and 80 °C, respectively, allowed us to reduce both the pretreatment time of the Cu-AHP stage and the chemical loadings. Incubating alkaline pre-extracted hybrid poplar for 12 h with 10% NaOH (w/w biomass), 8% hydrogen peroxide (w/w biomass), and a Cu2+ and 2,2′-bipyridine (bpy) concentration of 1 mM yielded monomeric sugar yields of approximately 77% glucose and 66% xylose (based on the initial sugar composition) following enzymatic hydrolysis. Technoeconomic analysis (TEA) indicates that these changes to the two-stage alkaline/Cu-AHP pretreatment process could potentially reduce the minimum fuel selling price (MFSP) by more than $1.00 per gallon of biofuel compared to the reference case where both stages were conducted at 30 °C with higher chemical inputs.

  • 2743.
    Yuwawech, Kitti
    et al.
    Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy, King Mongkut's University of Technology Thonburi(KMUTT), Bangkok.
    Wootthikanokkhan, Jatuphorn
    Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy, King Mongkut's University of Technology (KMUTT)Thonburi, Bangkok .
    Tanpichai, Supachok
    Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy, King Mongkut's University of Technology (KMUTT)Thonburi, Bangkok .
    Effects of Two Different Cellulose Nanofiber Types on Properties of Poly(vinyl alcohol) Composite Films2015Ingår i: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, Vol. 2015, artikel-id 908689Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work concerns a study on the effects of fiber types and content of cellulose nanofiber on mechanical, thermal, and optical properties polyvinyl alcohol (PVA) composites. Two different types of cellulose nanofibers, which are nanofibrillated cellulose (NFC) and bacterial cellulose (BC), were prepared under various mechanical treatment times and then incorporated into the PVA prior to the fabrication of composite films. It was found that tensile modulus of the PVA film increased with nanofibers content at the expense of its percentage elongation value. DSC thermograms indicate that percentage crystallinity of PVA increased after adding 2-4 wt% of the fibers. This contributed to the better mechanical properties of the composites. Tensile toughness values of the PVA/BC nanocomposite films were also superior to those of the PVA/NFC system containing the same fiber loading. SEM images of the composite films reveal that tensile fractured surface of PVA/BC experienced more ductile deformation than the PVA/NFC analogue. The above discrepancies were discussed in the light of differences between the two types of fibers in terms of diameter and their intrinsic properties. Lastly, percentage total visible light transmittance values of the PVA composite films were greater than 90%, regardless of the fiber type and content.

  • 2744.
    Yuwawech, Kitti
    et al.
    Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy, King Mongkut's University of Technology Thonburi(KMUTT), Bangkok.
    Wootthikanokkhan, Jatuphorn
    Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy, King Mongkut's University of Technology (KMUTT)Thonburi, Bangkok .
    Tanpichai, Supachok
    Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy, King Mongkut's University of Technology (KMUTT)Thonburi, Bangkok .
    Enhancement of thermal, mechanical and barrier properties of EVA solar cell encapsulating films by reinforcing with esterified cellulose nanofibres2015Ingår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 48, s. 12-22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Solar cell encapsulating film based on ethylene vinyl acetate copolymer (EVA) was modified by using bacterial cellulose (BC) nanofibres. Bacterial cellulose was chemically modified with propionic anhydride prior to compounding with EVA in a twin screw extruder. The effects of fibre content on the mechanical, thermal, optical and barrier properties of the EVA composite films were investigated. Better mechanical and barrier properties of the EVA films were obtained when the modified BC nanofibres were used. The results were ascribed to the different chemical functional groups on the fibre surface, as verified by FTIR spectra. Deacetylation of the EVA was delayed and visible light transparency of the EVA films above 75% was retained. Overall, our study showed that it was possible to improve the barrier properties of EVA film without sacrificing much transparency by using a suitable type and content of cellulose nanofibres.

  • 2745.
    Yuwawech, Kitti
    et al.
    Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy, King Mongkut's University of Technology (KMUTT)Thonburi, Bangkok .
    Wootthikanokkhan, Jatuphorn
    Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy, King Mongkut's University of Technology (KMUTT)Thonburi, Bangkok .
    Wanwong, Sompit
    Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy, King Mongkut's University of Technology (KMUTT)Thonburi, Bangkok .
    Tanpichai, Supachok
    School of EnergyEnvironment and Materials, King Mongkut's University of Technology Thonburi (KMUTT)Bangkok .
    Polyurethane/esterified cellulose nanocrystal composites as a transparent moisture barrier coating for encapsulation of dye sensitized solar cells2017Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 134, nr 45, artikel-id 45010Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This research work aims to investigate the effects of types and concentration of cellulose nanocrystals (CNCs) prepared from bacterial cellulose (BC) and nanofibrillated cellulose (NFC) on structure properties of polyurethane (PU) composites. Feasibility of applying the polymer composite for encapsulation of dye sensitized solar cells was of interest. Both CNCs were pretreated via esterification before mixing with the polyurethane by a solution process. Tensile strength and thermal stability of the PU/esterified CNCs were found to be superior to those of the systems reinforced with untreated CNCs. With the introduction of both untreated and esterified CNCs, water vapor transmission rates through the PU composite films were lowered while their visible light transmittance values were maintained to be above 80%. Also, better efficiency and stability of the solar cell were obtained when the PU was reinforced with CNCs, indicating its longer lifetime usage. The most suitable cell, described in terms of durability, was obtained when the PU was mixed with 2 wt % of esterified CNCs obtained from BC. Overall, this study shows that the surface modification of the CNCs is an important factor, affecting the reinforcing efficacy.

  • 2746.
    Zafar, Muhammad Abdullah
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Optimization of Combined heat and power plant (CHP) integrated with transportation fuel2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Regional energy system consists of the three sections heat, electricity and transport. The alternatives of fossil fuels are getting importance in research fields to reduce its adverse effect on the environment, especially in the transport sector. The bioethanol is focusing on recent years to reduce the greenhouse gas (GHG) emission and energy dependence on other countries.

    This study focus on analyzing the energy system including the heat and power plant integrating with transportation fuel production with the best utilization of the locally available energy resources. The four regions of vastmanland Vasteras, Koping, Norberg, Skinskatterberg are considered for the energy resources due to its large arable land. The data regarding local energy resources (household waste, peat and wood chips, coal) used in CHP plant are taken from the different bureau and some are assumed as seen in the previous year's trends. The four crops ( winter wheat, spring wheat, spring barley, and oats) are focused for biofuel production in the integrated plant. It is very difficult to predict the crops production and its hectares areas because it is dependent upon the weather conditions. The passenger cars only considered for calculating the biofuel demand in considered regions because data is easily available.

    The dynamic model is developed for the optimization of the ethanol plant integrated with CHP plant to reduce the system cost and reduction of the greenhouse gas (GHG) emission.  The mixed integer programming is the best way for system optimization and it developed with the help of the GAMS, which is best suited for complex problems.

     The four case studies are analyzed in which different parameters are changed from 2017 to 2030 years. In the first scenario, all parameters are changed next fourteen years with previous trends. The vehicle's number run on gasoline, straw production hectares area and its production are changed in second, third and fourth scenarios respectively.

     The CHP produce the heat and electricity with local fuels and import fuels which have the cheapest production prices. The fuel E05 and tall oil pitch are also considered to use in the system but due to its heavy prices is not used. The region heat and electricity demand satisfied by importing to the region as compared to produce with some sources are very high prices.  The huge amount of ethanol is produced in each scenario because demand is very little in regions, large amount exported all scenario.  The ethanol import in the last three years of the second scenario because the production of ethanol is less and demand is high. The ethanol demand and production is equal from 3rd year to 5th year in the fourth scenario. The exported ethanol l to another region can provide the fuel to more than 500,000 passenger cars in each scenario.

    The ethanol utilization in the region can reduce the CO2 emission effectively. The first scenario emitted 120-140Kt CO2 during fourteen years while it reduced to 89 Kt and 77 Kt in the third and fourth scenario. It reduced 36% and 45% CO2 if  10%/year and 50%/years vehicles run by gasoline cars shifted to E85.

  • 2747.
    Zafarani-Moattar, Mohammed Taghi
    et al.
    Physical Chemistry Department, University of Tabriz.
    Sadeghi, Rahmat
    Physical Chemistry Department, University of Tabriz.
    Sarmad, Shokat
    Physical Chemistry Department, University of Tabriz.
    Measurement and modeling of densities and sound velocities of the systems poly(propylene glycol) + methanol, +ethanol, +1-propanol, +2-propanol and +1-butanol at T = 298.15 K2006Ingår i: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 38, nr 3, s. 257-263Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Experiments have been performed at T = 298.15 K to measure the density and sound velocity of the systems {poly(propylene glycol) + methanol, +ethanol, +1-propanol, 2-propanol and +1-butanol} over the whole range of composition. From these measurements, values of the excess molar volume (Vmex)">(Vmex) and excess molar isentropic compression, Ks,mex">Ks,mex , equal to -(&#x2202;Vmex/&#x2202;p)s">-(∂Vmex/∂p)s were calculated. The excess molar volume for all of these systems were found to be negative and decreases in magnitude as size of alcohol increases, except for 2-propanol solutions for which the magnitude of the excess volume is higher than that of 1-butanol solutions. Expressions for VmexandKs,mex">VmexandKs,mex of polymer solutions were obtained for the model of Flory–Huggins and the polymer non-random two liquid (NRTL) model. These expressions were used to fit the experimental VmexandKs,mex">VmexandKs,mex data of the investigated systems.

  • 2748.
    Zafarani-Moattar, Mohammed Taghi
    et al.
    Physical Chemistry Department, Faculty of Chemistry (Excellence of Science for New Materials and Clean Chemistry) University of Tabriz.
    Sarmad, Shokat
    Physical Chemistry Department, Faculty of Chemistry (Excellence of Science for New Materials and Clean Chemistry) University of Tabriz.
    Apparent molar volumes, apparent isentropic compressibilities, and viscosity B-coefficients of 1-ethyl-3-  methylimidazolium bromide in aqueous di-potassium hydrogen phosphate and potassium di-hydrogen phosphate solutions at T = (298.15, 303.15, 308.15, 313.15, and 318.15) K2012Ingår i: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 54, s. 192-203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Apparent molar volumes Vϕ, apparent isentropic compressibilities κϕ, and viscosity B-coefficients for 1-ethyl-3-methylimidazolium bromide (EmimBr) in aqueous di-potassium hydrogen phosphate (K2HPO4) solutions with salt weight fractions (ws = 0.00, 0.10, 0.15, and 0.20) and potassium di-hydrogen phosphate (KH2PO4) solutions with salt weight fractions (ws = 0.00, 0.04, 0.07, and 0.10) have been determined from solution density, sound velocity and viscosity measurements at temperatures over the range (298.15 to 318.15) K as function of concentration of 1-ethyl-3-methylimidazolium bromide (EmimBr). In the investigated temperature range, the relation: Vϕ0=a0+a1T+a2T2, has been used to describe the temperature dependence of the standard partial molar volumes Vϕ0. These results have, in conjunction with the results obtained in pure water, been used to deduce the standard volumes of transfer ΔVϕ0 and viscosity B-coefficients of transfer for 1-ethyl-3-methylimidazolium bromide from water to aqueous K2HPO4 and KH2PO4 solutions for rationalizing various interactions in the ternary solutions. The structure making or breaking ability of 1-ethyl-3-methylimidazolium bromide has been discussed in terms of the sign of ∂2Vϕ0∂T2. An increase in the transfer volume of 1-ethyl-3-methylimidazolium bromide with increasing phosphate salts concentration has been explained by Friedman–Krishnan co-sphere model. The activation parameters of viscous flow for the ternary solutions investigated were also determined and discussed by the application of transition state theory.

  • 2749.
    Zafarani-Moattar, Mohammed Taghi
    et al.
    Physical Chemistry Department, Faculty of Chemistry (Excellence of Science for New Materials and Clean Chemistry) University of Tabriz.
    Sarmad, Shokat
    Effect of tri-potassium phosphate on volumetric, acoustic, and transport behaviour of aqueous solutions of 1-ethyl-3-methylimidazolium bromide at T = (298.15 to 318.15) K2010Ingår i: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 42, nr 10, s. 1213-1221Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Density, sound velocity, and viscosity of 1-ethyl-3-methylimidazolium bromide, [Emim][Br], in aqueous solutions of tri-potassium phosphate with salt weight fractions (ws = 0.00, 0.10, 0.15, and 0.20) have been measured as a function of concentration of [Emim][Br] at atmospheric pressure and T = (298.15, 303.15, 308.15, 313.15, and 318.15) K. The apparent molar volume, isentropic compressibility, apparent isentropic compressibility, and relative viscosity values have been evaluated from the experimental data. The partial molar volume and isentropic compressibility at infinite dilution, and viscosity B-coefficient obtained from these data have been used to calculate the corresponding transfer parameters for the studied IL from water to the aqueous tri-potassium phosphate solutions. Also, an empirical equation was satisfactorily used to correlate the experimental viscosity data.

  • 2750.
    Zafarani-Moattar, Mohammed Taghi
    et al.
    Physical Chemistry Department, Faculty of Chemistry (Excellence of Science for New Materials and Clean Chemistry) University of Tabriz.
    Sarmad, Shokat
    Physical Chemistry Department, University of Tabriz.
    Osmotic and activity coefficient of 1-ethyl-3-methylimidazolium bromide in aqueous solutions of potassium dihydrogen phosphate, dipotassium hydrogen phosphate, and tripotassium phosphate at T = 298.15 K2010Ingår i: Journal of Chemical and Engineering Data, ISSN 0021-9568, E-ISSN 1520-5134, Vol. 55, nr 11, s. 5182-5190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Vapor−liquid equilibrium data (water activity, vapor pressure, osmotic coefficient, and activity coefficient) of the mixed electrolyte aqueous solution, 1-ethyl-3-methylimidazolium bromide, [Emim][Br], + tripotassium phosphate, [Emim][Br], + dipotassium hydrogen phosphate, [Emim][Br], + potassium dihydrogen phosphate, and their corresponding binary aqueous solutions have been measured by the isopiestic method at temperature 298.15 K. The osmotic coefficients for binary aqueous solutions were correlated to the Pitzer and modified Pitzer models. From these data, the corresponding mean molal activity coefficients, γ±, have been calculated. The activity coefficients of mixed electrolytes were calculated by Scatchard’s neutral-electrolyte method. The activity results were also satisfactorily fitted to the semiempirical equation.

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