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  • 1.
    Barzegar, Hamid Reza
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics. Department of Physics, University of California, Berkeley, CA 94720, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
    Yan, Aiming
    Coh, Sinisa
    Gracia-Espino, Eduardo
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Ojeda-Aristizabal, Claudia
    Dunn, Gabriel
    Cohen, Marvin L.
    Louie, Steven G.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zettl, Alex
    Spontaneous twisting of a collapsed carbon nanotube2017In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 10, no 6, 1942-1949 p.Article in journal (Refereed)
    Abstract [en]

    We study the collapsing and subsequent spontaneous twisting of a carbon nanotube by in situ transmission electron microscopy (TEM). A custom-sized nanotube is first created in the microscope by selectively extracting shells from a parent multi-walled tube. The few-walled, large-diameter daughter nanotube is driven to collapse via mechanical stimulation, after which the ribbon-like collapsed tube spontaneously twists along its long axis. In situ diffraction experiments fully characterize the uncollapsed and collapsed tubes. The experimental observations and associated theoretical analysis indicate that the origin of the twisting is compressive strain.

  • 2.
    Chandolias, Konstantinos
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lignocellulosic Biorefinery for Biohydrogen and Carboxylic Acids Production in Flexible Membrane Bioreactor and Two-stage System2017In: 7th Nordic Wood Biorefinery Conference. 28-30 March 2017. Stockholm, 2017Conference paper (Other academic)
    Abstract [en]

    Lignocellulosic biorefineries can produce numerous biofuels and chemicals via the anaerobic digestion process. Although several works have been recently conducted on this field, the technology is considered new and more research efforts are required towards industrialisation. In this work, wheat straw was digested after hydrolysis with dilute phosphoric acid. The substrate was biologically converted into carboxylic acids and biohydrogen at different OLRs (4.42-17.95 g COD/L.d). The semi-continuous experiments took place at 55 °C, both in reactors with free-cells or mixed free and membrane-encased cells, According to the results, the optimum biohydrogen, acetic and isobutyric acid yields were obtained at OLR of 4.42 g COD/L.d. Moreover, the highest lactic acid production was recorded at OLR of 9.33 g COD/L.d. Furthermore, a reactor containing both free and membrane-encased cells showed 60% higher lactic acid production (at OLR of 13.42 g COD/L.d) in comparison to the conventional free cell reactor. In addition, the production of acetic and isobutyric acid was greatly improved by a two-stage system. The use of both free and encased cells in a flexible membrane system along with the two-stage system for the optimisation of the process is the main novelty of this work.

  • 3. Cheeseman, J. D.
    et al.
    Tocilj, A.
    Park, Seongsoon
    KTH, Superseded Departments, Biochemistry and Biotechnology. Department of Chemistry, McGill University, Canada .
    Schrag, J. D.
    Kazlauskas, R. J.
    Structure of an aryl esterase from Pseudomonas fluorescens2004In: Acta Crystallographica Section D: Biological Crystallography, ISSN 0907-4449, E-ISSN 1399-0047, Vol. 60, no 7, 1237-1243 p.Article in journal (Refereed)
    Abstract [en]

    The structure of PFE, an aryl esterase from Pseudomonas fluorescens, has been solved to a resolution of 1.8 Å by X-ray diffraction and shows a characteristic α/β-hydrolase fold. In addition to catalyzing the hydrolysis of esters in vitro, PFE also shows low bromoperoxidase activity. PFE shows highest structural similarity, including the active-site environment, to a family of non-heme bacterial haloperoxidases, with an r.m.s. deviation in 271 Cα atoms between PFE and its five closest structural neighbors averaging 0.8 Å. PFE has far less similarity (r.m.s. deviation in 218 Cα atoms of 5.0 Å) to P. fluorescens carboxyl esterase. PFE favors activated esters with small acyl groups, such as phenyl acetate. The X-ray structure of PFE reveals a significantly occluded active site. In addition, several residues, including Trp28 and Met95, limit the size of the acyl-binding pocket, explaining its preference for small acyl groups.

  • 4.
    Hao, Nanjing
    et al.
    Department of Chemistry, University of Massachusetts, USA.
    Neranon, Kitjanit
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Department of Chemistry, University of Massachusetts, USA.
    Glyconanomaterials for biosensing applications2016In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 76, no 15, 113-130 p.Article in journal (Refereed)
    Abstract [en]

    Nanomaterials constitute a class of structures that have unique physiochemical properties and are excellent scaffolds for presenting carbohydrates, important biomolecules that mediate a wide variety of important biological events. The fabrication of carbohydrate-presenting nanomaterials, glyconanomaterials, is of high interest and utility, combining the features of nanoscale objects with biomolecular recognition. The structures can also produce strong multivalent effects, where the nanomaterial scaffold greatly enhances the relatively weak affinities of single carbohydrate ligands to the corresponding receptors, and effectively amplifies the carbohydrate-mediated interactions. Glyconanomaterials are thus an appealing platform for biosensing applications. In this review, we discuss the chemistry for conjugation of carbohydrates to nanomaterials, summarize strategies, and tabulate examples of applying glyconanomaterials in in vitro and in vivo sensing applications of proteins, microbes, and cells. The limitations and future perspectives of these emerging glyconanomaterials sensing systems are furthermore discussed.

  • 5. Honarvar, H.
    et al.
    Strand, J.
    Perols, Anna
    KTH, School of Biotechnology (BIO), Protein Technology.
    Orlova, Anna
    Selvaraju, R. K.
    Eriksson Karlström, Amelie
    KTH, School of Biotechnology (BIO), Protein Technology.
    Tolmachev, V.
    Position for site-specific attachment of a DOTA chelator to synthetic affibody molecules has a different influence on the targeting properties of 68Ga-Compared to 111in-labeled conjugates2014In: Molecular Imaging, ISSN 1535-3508, E-ISSN 1536-0121, Vol. 13, no 10Article in journal (Refereed)
    Abstract [en]

    Affibody molecules, small (7 kDa) scaffold proteins, are a promising class of probes for radionuclide molecular imaging. Radiolabeling of Affibody molecules with the positron-emitting nuclide 68Ga would permit the use of positron emission tomography (PET), providing better resolution, sensitivity, and quantification accuracy than single-photon emission computed tomography (SPECT). The synthetic anti-HER2 ZHER2:S1 Affibody molecule was conjugated with DOTA at the N-terminus, in the middle of helix 3, or at the Cterminus. The biodistribution of 68Ga-and 111In-labeled Affibody molecules was directly compared in NMRI nu/nu mice bearing SKOV3 xenografts. The position of the chelator strongly influenced the biodistribution of the tracers, and the influence was more pronounced for 68Ga-labeled Affibody molecules than for the 111In-labeled counterparts. The best 68Ga-labeled variant was 68Ga-[DOTA-A1]-ZHER2:S1, which provided a tumor uptake of 13 ± 1 %ID/g and a tumor to blood ratio of 39 ± 12 at 2 hours after injection. 111In-[DOTA-A1]-ZHER2:S1 and 111In-[DOTA-K58]-ZHER2:S1 were equally good at this time point, providing a tumor uptake of 15 to 16 %ID/g and a tumor to blood ratio in the range of 60 to 80. In conclusion, the selection of the best position for a chelator in Affibody molecules can be used for optimization of their imaging properties. This may be important for the development of Affibody-based and other protein-based imaging probes.

  • 6.
    Ingemarson, Rolf
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Herpes simplex ribonucleotide reductase1989Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In all bacterial, plant and animal cells, as well as in many viruses, genetic information resides in DNA (deoxyribonucleic acid). Replication of DNA is essential for proliferation, and DNA-containing viruses (such as herpesviruses) must carry out this process within the mammalian cells they infect. The enzyme ribonucleotide reductase catalyzes the first unique step leading to the production of the four deoxy-ribonucleotides used to make DNA. Each deoxyribonucleotide is produced by reduction of the corresponding ribonucleotide. After infection of a mammalian cell with herpes simplex virus (HSV) a new ribonucleotide reductase activity appears, which is distinct from the mammalian enzyme activity. This is due to induction of a separate, virally-encoded ribonucleotide reductase. Two monoclonal antibodies were raised against HSV (type 1) ribonucleotide reductase, and were found to bind but not neutralize its enzyme activity. One antibody recognized a larger (140 kD) protein and the other a smaller (40 kD) protein, suggesting the HSV 1 ribonucleotide reductase had a heterodimeric composition similar to that found in many other organisms. The 140 kD protein was sequentially degraded to 110 kD, 93 kD and 81 kD proteins by a host (Vero) cell-specific serine protease. Of these different proteolytic products, at least the 93 kD residue was enzymatically active, suggesting that part of the 140 kD protein may have functions unrelated to ribonucleotide reduction. The 140 and 40 kD proteins bound tightly to each other in a complex of the a2ß2 type, as shown by analytical glycerol gradient centrifugation. An assay system for functional small and large subunits of HSV 1 ribonucleotide reductase was developed, using two temperaturesensitive mutant viruses, defective in either the large (tsl207) or small (tsl222) subunits. Active holoenzyme was reconstituted both in vitro, by mixing extracts from cells infected with either mutant, and in vivo by coinfection of cells with both mutants. The gene encoding the small subunit of HSV 1 ribonucleotide reductase was cloned into an expression plasmid under control of a tac promoter. The recombinant protein was purified to homogeneity from extracts of transfected E. coli, and was active when combined with large subunit, as provided by extracts of tsl222- infected hamster (BHK) cells. The protein contained a novel tyrosyl free radical that spectroscopically resembled, but was distinguishable from, the active-site free radical found in either the E. coli or mammalian small subunits of ribonucleotide reductase. The gene encoding the large subunit of HSV 1 ribonucleotide reductase was also expressed in E. coli, using similar techniques. The recombinant large subunit was immunoprecipitated from extracts of transfected bacteria, and showed weak activity when combined with small subunit, provided by extracts of tsl20-infected hamster (BHK) cells.

  • 7. Li, Ågot
    et al.
    Sem, Signe
    Håland, Julie Tesdal
    Petersen, Jens Højslev
    Jensen, Lisbeth Krüger
    Nordic project food contact materials: Control of declarations of compliance (DoC)2015Book (Other academic)
    Abstract [en]

    Denmark, Finland, Faroe Islands, Iceland, Norway and Sweden have in 2013–2015 conducted a Nordic project on food contact materials. Food contact materials are used in all stages of food production and can be a general source of contamination. The food safety authorities in most of the Nordic countries have had a limited focus on the FCM area with the exception of Denmark and Finland. The aim of the project was therefore to control establishments producing, importing or using plastic food contact materials as well as to increase the knowledge of the inspectors performing these controls. The focus of the inspections was to control the declaration of compliance (DoC) for plastic food contact materials. The requirement for a Doc is mandatory in order to ensure that the FCM complies with the legislation. In addition some products were analyzed for phthalates.

  • 8. Mohl, Melinda
    et al.
    Dobo, Dorina
    Kukovecz, Akos
    Konya, Zoltan
    Kordas, Krisztian
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wei, Jinquan
    Vajtai, Robert
    Ajayan, Pulickel M.
    Formation of CuPd and CuPt Bimetallic Nanotubes by Galvanic Replacement Reaction2011In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 19, 9403-9409 p.Article in journal (Refereed)
    Abstract [en]

    A galvanic replacement reaction has been successfully applied to prepare CuPd and CuPt bimetallic nanotubes. The nanotubes were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. Ultralong, single crystalline copper nanowires (NWs) with a diameter of similar to 64 nm and a length of several micrometers were used as template material. By controlling the amount of noble metal salt added, nanotubes with different compositions were obtained. After the replacement of Cu with Pt, nanotubes composed of a PtCu alloy were formed. EDS analysis revealed that the Pt content increased until about 66%. No further increase in the molar ratio resulted in any additional Pt incorporation into the alloy. As for the replacement of Cu with Pd, the thickening of the nanotubes was observed indicating that nanotubes composed of Pd nanoparticles were formed. Bacicscattered electron imaging and SEM-EDS revealed CuPd nanotubes with approximately 2.3% Cu content. These remarks indicate different evolution mechanism for the nanotubes in the two systems.

  • 9.
    Neranon, Kitjanit
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stimuli-Responsive, Multivalent Glycodendrimer/Metalloglycodendrimer Assemblies for Targeted DeliveryManuscript (preprint) (Other academic)
  • 10. Nordlander, E.
    et al.
    Thorin, E.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes. Mälardalen University, Sweden.
    Investigating the possibility of applying an ADM1 based model to a full-scale co-digestion plant2017In: Biochemical engineering journal, ISSN 1369-703X, E-ISSN 1873-295X, Vol. 120, 73-83 p.Article in journal (Refereed)
    Abstract [en]

    This study investigated the possibility of using a model based on the anaerobic digestion model no. 1 (ADM1) on a full-scale 4000 m3 digester in order to understand how such theoretical models can be applied to a real industrial process. The industrial scale digester co-digests the organic fraction of municipal solid waste, grease trap sludge, and ley crop silage with varying feed rates and amounts of volatile solids. A year of process data was collected. Biogas flow, methane content/flow, and ammonia nitrogen were the variables that the model was best at predicting (index of agreement at 0.78, 0.61/0.77, and 0.68, respectively). The model was also used to investigate the effect of increasing the volatile solids (VS) concentration entering the digester. According to simulation results, increasing the influent VS concentration will increase biogas and methane outflow (from 1.5 million Nm3 methane to more than 2 million Nm3 methane), but decrease the amounts of biogas/methane per unit of volatile solids (from about 264 Nm3 methane per tonne VS to below 215 Nm3 methane per tonne VS).

  • 11.
    Olofsson, Martin
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lamela, Teresa
    Necton SA, Olhao, Portugal.
    Nilsson, Emmelie
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Bergé, Jean-Pascal
    IFREMER, Nantes, France.
    del Pino, Victória
    Necton SA, Olhao, Portugal.
    Uronen, Pauliina
    Neste Oil, Ctr Technol, Porvoo, Finland.
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata 2014In: Marine Drugs, ISSN 1660-3397, Vol. 12, no 4, 1891-1910 p.Article in journal (Refereed)
    Abstract [en]

    Instead of sole nutrient starvation to boost algal lipid production, we addressed nutrient limitation at two different seasons (autumn and spring) during outdoor cultivation in flat panel photobioreactors. Lipid accumulation, biomass and lipid productivity and changes in fatty acid composition of Nannochloropsis oculata were investigated under nitrogen (N) limitation (nitrate:phosphate N:P 5, N:P 2.5 molar ratio). N. oculata was able to maintain a high biomass productivity under N-limitation compared to N-sufficiency (N:P 20) at both seasons, which in spring resulted in nearly double lipid productivity under N-limited conditions (0.21 g L−1 day−1) compared to N-sufficiency (0.11 g L−1 day−1). Saturated and monounsaturated fatty acids increased from 76% to nearly 90% of total fatty acids in N-limited cultures. Higher biomass and lipid productivity in spring could, partly, be explained by higher irradiance, partly by greater harvesting rate (~30%). Our results indicate the potential for the production of algal high value products (i.e., polyunsaturated fatty acids) during both N-sufficiency and N-limitation. To meet the sustainability challenges of algal biomass production, we propose a dual-system process: Closed photobioreactors producing biomass for high value products and inoculum for larger raceway ponds recycling waste/exhaust streams to produce bulk chemicals for fuel, feed and industrial material.

  • 12. Portugal-Nunes, Diogo J
    et al.
    Pawar, Sudhanshu S
    RISE, Hållbar samhällsbyggnad, Sweden.
    Lidén, Gunnar
    Gorwa-Grauslund, Marie F
    Effect of nitrogen availability on the poly-3-D-hydroxybutyrate accumulation by engineered Saccharomyces cerevisiae.2017In: AMB Express, Vol. 7, no 1, 35Article in journal (Refereed)
    Abstract [en]

    Poly-3-D-hydroxybutyrate (or PHB) is a polyester which can be used in the production of biodegradable plastics from renewable resources. It is naturally produced by several bacteria as a response to nutrient starvation in the excess of a carbon source. The yeast Saccharomyces cerevisiae could be an alternative production host as it offers good inhibitor tolerance towards weak acids and phenolic compounds and does not depolymerize the produced PHB. As nitrogen limitation is known to boost the accumulation of PHB in bacteria, the present study aimed at investigating the effect of nitrogen availability on PHB accumulation in two recombinant S. cerevisiae strains harboring different xylose consuming and PHB producing pathways: TMB4443 expressing an NADPH-dependent acetoacetyl-CoA reductase and a wild-type S. stipitis XR with preferential use of NADPH and TMB4425 which expresses an NADH-dependent acetoacetyl-CoA reductase and a mutated XR with a balanced affinity for NADPH/NADH. TMB4443 accumulated most PHB under aerobic conditions and with glucose as sole carbon source, whereas the highest PHB concentrations were obtained with TMB4425 under anaerobic conditions and xylose as carbon source. In both cases, the highest PHB contents were obtained with high availability of nitrogen. The major impact of nitrogen availability was observed in TMB4425, where a 2.7-fold increase in PHB content was obtained. In contrast to what was observed in natural PHB-producing bacteria, nitrogen deficiency did not improve PHB accumulation in S. cerevisiae. Instead the excess available carbon from xylose was shunted into glycogen, indicating a significant gluconeogenic activity on xylose.

  • 13.
    Stangenberg, Friedhelm
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Agren, S.
    Karlsson, Sigbritt
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Quality assessments of recycled plastics by spectroscopy and chromatography2004In: Chromatographia, ISSN 0009-5893, E-ISSN 1612-1112, Vol. 59, no 02-jan, 101-106 p.Article in journal (Refereed)
    Abstract [en]

    Quality assessments will be important for improved use of recycled polymeric materials. Ongoing preparation of new standards in the area of recycled polymers needs an overview of which properties and thus which polymer ckaracterisation methods that will be important for that purpose. We suggest three polymeric properties as important for this work; these are degree of mixing (composition), degree of degradation and number and amount of low molecular weight compounds (e.g. degradation products, additives, flavour compounds). DSC showed increased degradation as multi modality for LDPE materials obtained from three different sites in a recycling plant. IR demonstrated that the carbonyl index increased during the various steps going from collected material to new product. GC chromatograms obtained for collected film Rakes, processed granules and ready-made bags were quite complex with a series of hydrocarbons among other compounds. The recycling process seems, however, to remove some of the low molecular weight compounds found in the incoming dirty material.

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