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  • 1.
    Auroux, Etienne
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Huseynova, Gunel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ràfols-Ribé, Joan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Miranda la Hera, Vladimir
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    A metal-free and transparent light-emitting device by sequential spray-coating fabrication of all layers including PEDOT:PSS for both electrodes2023Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 13, nr 25, s. 16943-16951Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The concept of a metal-free and all-organic electroluminescent device is appealing from both sustainability and cost perspectives. Herein, we report the design and fabrication of such a light-emitting electrochemical cell (LEC), comprising a blend of an emissive semiconducting polymer and an ionic liquid as the active material sandwiched between two poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) conducting-polymer electrodes. In the off-state, this all-organic LEC is highly transparent, and in the on-state, it delivers uniform and fast to turn-on bright surface emission. It is notable that all three device layers were fabricated by material- and cost-efficient spray-coating under ambient air. For the electrodes, we systematically investigated and developed a large number of PEDOT:PSS formulations. We call particular attention to one such p-type doped PEDOT:PSS formulation that was demonstrated to function as the negative cathode, as well as future attempts towards all-organic LECs to carefully consider the effects of electrochemical doping of the electrode in order to achieve optimum device performance.

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  • 2.
    Brant Carvalho, Paulo H. B.
    et al.
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
    Moraes, Pedro Ivo R.
    Department of Chemistry, Federal University of Juiz de Fora, MG, Juiz de Fora, Brazil.
    Leitão, Alexandre A.
    Department of Chemistry, Federal University of Juiz de Fora, MG, Juiz de Fora, Brazil.
    Andersson, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Tulk, Chris A.
    Neutron Scattering Division, Oak Ridge National Laboratory, TN, Oak Ridge, United States.
    Molaison, Jamie
    Neutron Scattering Division, Oak Ridge National Laboratory, TN, Oak Ridge, United States.
    Lyubartsev, Alexander P.
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
    Häussermann, Ulrich
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
    Structural investigation of three distinct amorphous forms of Ar hydrate2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 49, s. 30744-30754Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three amorphous forms of Ar hydrate were produced using the crystalline clathrate hydrate Ar·6.5H2O (structure II, Fd3m, a ≈ 17.1 Å) as a precursor and structurally characterized by a combination of isotope substitution (36Ar) neutron diffraction and molecular dynamics (MD) simulations. The first form followed from the pressure-induced amorphization of the precursor at 1.5 GPa at 95 K and the second from isobaric annealing at 2 GPa and subsequent cooling back to 95 K. In analogy to amorphous ice, these amorphs are termed high-density amorphous (HDA) and very-high-density amorphous (VHDA), respectively. The third amorph (recovered amorphous, RA) was obtained when recovering VHDA to ambient pressure (at 95 K). The three amorphs have distinctly different structures. In HDA the distinction of the original two crystallographically different Ar guests is maintained as differently dense Ar–water hydration structures, which expresses itself in a split first diffraction peak in the neutron structure factor function. Relaxation of the local water structure during annealing produces a homogeneous hydration environment around Ar, which is accompanied with a densification by about 3%. Upon pressure release the homogeneous amorphous structure undergoes expansion by about 21%. Both VHDA and RA can be considered frozen solutions of immiscible Ar and water in which in average 15 and 11 water molecules, respectively, coordinate Ar out to 4 Å. The local water structures of HDA and VHDA Ar hydrates show some analogy to those of the corresponding amorphous ices, featuring H2O molecules in 5- and 6-fold coordination with neighboring molecules. However, they are considerably less dense. Most similarity is seen between RA and low density amorphous ice (LDA), which both feature strictly 4-coordinated H2O networks. It is inferred that, depending on the kind of clathrate structure and occupancy of cages, amorphous states produced from clathrate hydrates display variable local water structures.

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  • 3.
    Chen, Hui
    et al.
    Wallenberg Wood Science Center, Department of Fiber and Polymer Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Montanari, Céline
    Wallenberg Wood Science Center;Department of Fiber and Polymer Technology;KTH Royal Institute of Technology;Stockholm;Sweden.
    Yan, Max
    Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden.
    Popov, Sergei
    Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden.
    Li, Yuanyuan
    Wallenberg Wood Science Center, Department of Fiber and Polymer Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Sychugov, Ilya
    Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden.
    Berglund, Lars A
    Wallenberg Wood Science Center, Department of Fiber and Polymer Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Refractive index of delignified wood for transparent biocomposites2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 67, s. 40719-40724Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Refractive index (RI) determination for delignified wood templates is vital for transparent wood composite fabrication. Reported RIs in the literature are based on either single plant fibers or wood powder, measured by the immersion liquid method (ILM) combined with mathematical fitting. However, wood structure complexity and the physical background of the fitting were not considered. In this work, RIs of delignified wood templates were measured by the ILM combined with a light transmission model developed from the Fresnel reflection/refraction theory for composite materials. The RIs of delignified balsa wood are 1.536 ± 0.006 and 1.525 ± 0.008 at the wavelength of 589 nm for light propagating perpendicular and parallel to the wood fiber direction, respectively. For delignified birch wood, corresponding values are 1.537 ± 0.005 and 1.529 ± 0.006, respectively. The RI data for delignified wood scaffolds are important for tailoring optical properties of transparent wood biocomposites, and also vital in optical properties investigations by theoretical modelling of complex light propagation in transparent wood and related composites. The developed light transmission model in combination with the immersion liquid method can be used to determine the RI of complex porous or layered solid materials and composites.

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  • 4.
    Fan, Junpeng
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ekspong, Joakim
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ashok, Anumol
    Koroidov, Sergey
    Gracia-Espino, Eduardo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Solid-state synthesis of few-layer cobalt-doped MoS2 with CoMoS phase on nitrogen-doped graphene driven by microwave irradiation for hydrogen electrocatalysis2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 56, s. 34323-34332Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The high catalytic activity of cobalt-doped MoS2 (Co–MoS2) observed in several chemical reactions such as hydrogen evolution and hydrodesulfurization, among others, is mainly attributed to the formation of the CoMoS phase, in which Co occupies the edge-sites of MoS2. Unfortunately, its production represents a challenge due to limited cobalt incorporation and considerable segregation into sulfides and sulfates. We, therefore, developed a fast and efficient solid-state microwave irradiation synthesis process suitable for producing thin Co–MoS2 flakes (∼3–8 layers) attached on nitrogen-doped reduced graphene oxide. The CoMoS phase is predominant in samples with up to 15 at% of cobalt, and only a slight segregation into cobalt sulfides/sulfates is noticed at larger Co content. The Co–MoS2 flakes exhibit a large number of defects resulting in wavy sheets with significant variations in interlayer distance. The catalytic performance was investigated by evaluating the activity towards the hydrogen evolution reaction (HER), and a gradual improvement with increased amount of Co was observed, reaching a maximum at 15 at% with an overpotential of 197 mV at −10 mA cm−2, and a Tafel slope of 61 mV dec−1. The Co doping had little effect on the HER mechanism, but a reduced onset potential and charge transfer resistance contributed to the improved activity. Our results demonstrate the feasibility of using a rapid microwave irradiation process to produce highly doped Co–MoS2 with predominant CoMoS phase, excellent HER activity, and operational stability.

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  • 5. Gemo, Nicola
    et al.
    Menegazzo, Federica
    Biasi, Pierdomenico
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Turku/Åbo, Finland .
    Sarkar, Anjana
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Raut, Dilip G.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kordás, Krisztián
    Rautio, Anne-Riikka
    Mohl, Melinda
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Åbo Akademi University, Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Turku/Åbo, Finland .
    TiO2 nanoparticles vs. TiO2 nanowires as support in hydrogen peroxide direct synthesis: the influence of N and Au doping2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 105, s. 103311-103319Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The performance of Pd on titania support were evaluated in the direct synthesis of hydrogen peroxide. The equipment used was a high pressure, semi-batch apparatus equipped with a special injection system. Pd (1 wt%) catalysts on TiO2 materials with different nature were prepared by wet impregnation method. Three aspects were investigated: (a) the structure of the support (nanoparticles vs. nanowires); (b) the addition of a second active metal (Au); (c) the influence of N-doping of the support. All samples were characterized by means of XPS, TEM and XRD analyses. TiO2 nanoparticle supported catalyst demonstrated higher H2O2 selectivity and higher turnover frequency (TOF) than the catalysts based on TiO2 nanowires. The addition of Au to the Pd TiO2 nanowire catalyst improved the H2O2 selectivity due to altered particle size and electronic effects. Both N-doped versions of the catalysts gave rise to higher H2O2 selectivity than the parent non-doped ones. The synthetic procedure was the source of this observation: larger mean Pd nanoparticles were present, thus favouring the formation of H2O2 as the primary product.

  • 6.
    Gracia-Espino, Eduardo
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Advanced Materials Department, IPICYT, Camino a la Presa San José 2055, Col. Lomas 4a sección, San Luis Potosí S.L.P., 78216, México. E-mail: flo@ipicyt.edu.mx.
    López-Urias, F.
    Terrones, H.
    Terrones, M.
    Electron transport study on functionalized armchair graphene nanoribbons: DFT calculations2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 26, s. 21954-21960Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quantum transport studies are performed on doped and functionalized 8- and 11-armchair graphene nanoribbons (aGNRs) by means of density functional theory. Substitutional doping is performed by introducing boron, nitrogen, oxygen, silicon, phosphorus, and sulfur atoms within the lattice of the aGNRs. Other functional groups such as borane, amine, hydroxyl, thiol, silane, silene, phosphine, and phosphorane groups are also introduced at the nanoribbon's edge. The dopant position and the nanoribbon's width strongly influence the current-voltage characteristics, and generally, the narrow 8-aGNRs and edge-doped 11-aGNRs show deteriorated transport properties, mainly due to the formation of irregular edges that create highly localized states disrupting several conducting bands. On the other hand, the inside-doped 11-aGNRs are barely affected, mainly because these systems preserve the edge's structure, thus edge conduction bands still contribute to the electron transport. Our results suggest that wider graphene nanoribbons could be functionalized at the inner sections without significantly compromising their transport characteristics while retaining the chemical reactivity that characterize doped nanocarbons. Such characteristics are highly desirable in fuel cells where doped graphene is used as a catalyst support or as a metal-free catalyst.

  • 7.
    Hu, Guangzhi
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Nitze, Florian
    Chalmers University of Technology.
    Jia, Xueen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sharifi, Tiva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Barzegar, Hamid Reza
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Gracia-Espino, Eduardo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Reduction free room temperature synthesis of a durable and efficient Pd/ordered mesoporous carbon composite electrocatalyst for alkaline direct alcohols fuel cell2014Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 4, nr 2, s. 676-682Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of easy and environmentally benign synthesis methods of efficient electrocatalysts for use in energy conversion applications motivates researchers all over the world. Here we report a novel and versatile method to synthesize well-dispersed palladium-functionalized ordered mesoporous carbons (Pd/OMCs) at room temperature without any reducing agent by one-pot mixing of tri(dibenzylideneacetone)palladium(0) (Pd2DBA3) and OMCs together in a common N,N-dimethylformamide (DMF) solution. The formation of Pd nanoparticles and their crystallization on the OMC is catalyzed by protons in the solution and can thus be controlled by the solution pH. The complete process and the as-prepared nanocomposite was characterized by UV-spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (HTEM), X-ray photoelectron spectrum (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The electrocatalytic property of the as-decorated material was examined with cyclic voltammetry (CV). The Pd/OMC composite shows up to two times higher electrocatalytic ability with a significantly better durability towards ethanol and methanol oxidation in alkaline media compared to commercial high surface area conductive carbon black Vulcan XC-72 decorated with equivalent Pd nanoparticles. Our described method provides new insight for the development of highly efficient carbon based nanocatalysts by simple and environmentally sound methods.

  • 8.
    Johansson, Emil
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Caraballo, Remi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Zocher, Georg
    Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
    Mistry, Nitesh
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Arnberg, Niklas
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Stehle, Thilo
    Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany; Vanderbilt University, School of Medicine, TN, Nashville, United States.
    Elofsson, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Exploring divalent conjugates of 5-N-acetyl-neuraminic acid as inhibitors of coxsackievirus A24 variant (CVA24v) transduction2022Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 12, nr 4, s. 2319-2331Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coxsackievirus A24 variant (CVA24v) is responsible for several outbreaks and two pandemics of the highly contagious eye infection acute hemorrhagic conjunctivitis (AHC). Currently, neither prevention (vaccines) nor treatments (antivirals) are available for combating this disease. CVA24v attaches to cells by binding Neu5Ac-containing glycans on the surface of cells which facilitates entry. Previously, we have demonstrated that pentavalent Neu5Ac conjugates attenuate CVA24v infection of human corneal epithelial (HCE) cells. In this study, we report on the structure-based design of three classes of divalent Neu5Ac conjugates, with varying spacer lengths, and their effect on CVA24v transduction in HCE cells. In relative terms, the most efficient class of divalent Neu5Ac conjugates are more efficient than the pentavalent Neu5Ac conjugates previously reported.

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  • 9.
    Khokarale, Santosh G.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, FI-20500 Åbo-Turku, Finland.
    Hydrogen sulfide gas capture by organic superbase 1,8-diazabicyclo-[5.4.0]-undec-7-ene through salt formation: salt synthesis, characterization and application for CO2 capture2018Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 8, nr 33, s. 18531-18541Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrogen sulfide (H2S) is a toxic and environment polluting gas like other acid gases and hence its capture and sequestration is equally important before release into the atmosphere. In this regard, solvent-based processes involving aqueous tertiary amine systems were extensively studied and used. Herein, in line with an analogous pathway, we report capture of H2S gas in the form of its salt with an organic superbase such as 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) and the obtained salt was thoroughly studied. Spectroscopic analyses such as NMR and FTIR analyses confirmed that the H2S molecule formed an ionic solid adduct with DBU through protonation of its sp2-hybridized N atom. The stability of formed [DBUH][SH] salt in aqueous solution as well as under thermal treatment was also studied and monitored by NMR and thermogravimetric analysis (TGA), respectively. In aqueous medium, compared to DBU, the [DBUH][SH] salt exhibited long term stability without decomposition whereas under thermal treatment both DBU and its salt with H2S turned out to be thermally unstable where salt showed a volatile nature like a sublimized solid. Dissolution feasibility of [DBUH][SH] salt was also compared with DBU in polar as well as non-polar solvents and even though the [DBUH][SH] salt had an ionic nature, like DBU, it was also found soluble in various polar and non-polar solvents. Considering the stability of [DBUH][SH] salt in aqueous medium, its aqueous solution was further explored as a solvent media for CO2 capture where the influence of process parameters such as the influence of concentration of water in the solvent and CO2 flow rate was studied. Most importantly, here we demonstrated the synthesis of [DBUH][SH] salt for easy capture of H2S gas following reaction with DBU under ambient reaction conditions.

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  • 10.
    Khokarale, Santosh G.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, FI-20500 Åbo - Turku, Finland.
    Metal free synthesis of ethylene and propylene carbonate from alkylene halohydrin and CO2 at room temperature2019Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 9, nr 58, s. 34023-34031Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Herein we describe a metal free and one-pot pathway for the synthesis of industrially important cyclic carbonates such as ethylene carbonate (EC) and propylene carbonates (PC) from molecular CO2 under mild reaction conditions. In the actual synthesis, the alkylene halohydrins such as alkylene chloro- or bromo or iodohydrin and organic superbase, 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) reacted equivalently with CO2 at room temperature. The syntheses of cyclic carbonates were performed in DMSO as a solvent. Both 1,2 and 1,3 halohydrin precursors were converted into cyclic carbonates except 2-bromo- and iodoethanol, which were reacted equivalently with DBU through n-alkylation and formed corresponding n-alkylated DBU salts instead of forming cyclic carbonates. NMR analysis was used to identify the reaction components in the reaction mixture whereas this technique was also helpful in terms of understanding the reaction mechanism of cyclic carbonate formation. The mechanistic study based on the NMR analysis studies confirmed that prior to the formation of cyclic carbonate, a switchable ionic liquid (SIL) formed in situ from alkylene chlorohydrin, DBU and CO2. As a representative study, the synthesis of cyclic carbonates from 1,2 chlorohydrins was demonstrated where the synthesis was carried out using chlorohydrin as a solvent as well as a reagent. In this case, alkylene chlorohydrin as a solvent not only replaced DMSO in the synthesis but also facilitated an efficient separation of the reaction components from the reaction mixture. The EC or PC, [DBUH][Cl] as well as an excess of the alkylene chlorhydrin were separated from each other following solvent extraction and distillation approaches. In this process, with the applied reaction conditions, >90% yields of EC and PC were achieved. Meanwhile, DBU was recovered from in situ formed [DBUH][Cl] by using NaCl saturated alkaline solution. Most importantly here, we developed a metal free, industrially feasible CO2 capture and utilization approach to obtain EC and PC under mild reaction conditions.

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  • 11. Konwar, Lakhya Jyoti
    et al.
    Mäki-Arvela, Päivi
    Thakur, Ashim Jyoti
    Kumar, Narendra
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University.
    Sulfonated carbon as a new, reusable heterogeneous catalyst for one-pot synthesis of acetone soluble cellulose acetate2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 11, s. 8829-8837Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A sulfonated carbon (SO3H/PhSO3H-carbon) catalyzed novel process was developed for the solvent free synthesis of acetone soluble-cellulose acetate (CA) via acetylation of cellulose with acetic anhydride. The SO3H/PhSO3H functionalized carbons easily outperformed the traditional solid acids (zeolites, heteropoly acids, Amberlyst-15 etc.) producing acetylated products with DS values between 1.6 and 2.94, in high yield (48-77% isolated yield) and under solvent free conditions, in a one-pot process. Further, it was possible to produce the commercially desired, soluble CA (DS values 2-2.7) in excellent yields ([similar]70%) from microcrystalline cellulose under optimized reaction conditions over the highly active mesoporous sulfonated catalyst (AC500S). A catalyst-to-cellulose (w/w) ratio of 1, acetic anhydride-to-AGU (anhydroglucose unit) mole ratio of 4.5 and reaction time of 12 h was applied. Additionally, the sulfonated catalyst could be easily recovered by centrifugal separation of the reaction mixture (diluted with acetone) and subsequently applied in the next reaction cycle with no significant reduction in yield and DS of CA over multiple reaction cycles.

  • 12.
    Kulshreshtha, Chandramouli
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Clement, Arul
    Pascher, Torbjoern
    Sundstroem, Villy
    Matyba, Piotr
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Investigating ultrafast carrier dynamics in perovskite solar cells with an extended π-conjugated polymeric diketopyrrolopyrrole layer for hole transportation2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 11, s. 6618-6624Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Here, we show a new diketopyrrole based polymeric hole-transport material (PBDTP-DTDPP, (poly[[2,5-bis(2-hexyldecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-alt-[[2,2′-(4,8-bis(4-ethylhexyl-1-phenyl)-benzo[1,2-b:4,5-b′]dithiophene)bis-thieno[3,2-b]thiophen]-5,5′-diyl]])) for application in perovskite solar cells. The material performance was tested in a solar cell with an optimized configuration, FTO/SnO2/perovskite/PBDTP-DTDPP/Au, and the device showed a power conversion efficiency of 14.78%. The device charge carrier dynamics were investigated using transient absorption spectroscopy. The charge separation and recombination kinetics were determined in a device with PBDTP-DTDPP and the obtained results were compared to a reference device. We find that PBDTP-DTDPP enables similar charge separation time (<∼4.8 ps) to the spiro-OMeTAD but the amount of nongeminate recombination is different. Specifically, we find that the polymeric PBDTP-DTDPP hole-transport layer (HTL) slows-down the second-order recombination much less than spiro-OMeTAD. This effect is of particular importance in studying the charge transportation in optimized solar cell devices with diketopyrrole based HTL materials.

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  • 13.
    Kumari, Kanchan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). DNA Nanotechnology & Application Laboratory, CSIR-Institute of Minerals & Materials Technology, Bhubaneswar, India.
    Kar, Avishek
    DNA Nanotechnology & Application Laboratory, CSIR-Institute of Minerals & Materials Technology, Bhubaneswar, India.
    Nayak, Ashok K.
    DNA Nanotechnology & Application Laboratory, CSIR-Institute of Minerals & Materials Technology, Bhubaneswar, India.
    Mishra, Sandip K.
    Cancer Biology Laboratory, Institute of Life Sciences, Bhubaneswar, India.
    Subudhi, Umakanta
    DNA Nanotechnology & Application Laboratory, CSIR-Institute of Minerals & Materials Technology, Bhubaneswar, India; Academy of Scientific & Innovative Research (AcSIR), Uttar Pradesh, Ghaziabad, India.
    miRNA-mediated alteration of sulfatase modifying factor 1 expression using self-assembled branched DNA nanostructures2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 18, s. 10670-10680Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sulfatase enzymes catalyze sulfate ester hydrolysis, thus deficiencies of sulfatases lead to the accumulation of biomolecules resulting in several disorders. One of the important sulfatases is estrone sulfatase that converts inactive estrone sulfate to active estradiol. Posttranslational modification of highly conserved cysteine residue leads to unique formylglycine in the active site of sulfatases being critical for its catalytic activity. The essential factor responsible for this modification of sulfatase is Sulfatase-Modifying Factor 1 (SUMF1). The role of estrone sulfatase is well evident in breast cancer progression. However, the function and regulation of SUMF1 in cancer are not studied. In the present study, for the first time, we have assessed the expression of SUMF1 in breast cancer and report the oncogenic behavior upon overexpression of SUMF1. Although increased expression or activity of SUMF1 is anticipated based on its function, the expression of SUMF1 was found to be reduced in breast cancer cells at both mRNA and protein levels. An estrogen receptor (ER) dependent expression of SUMF1 was observed and higher SUMF1 expression is associated with improved breast cancer patient survival in ER-positive cases. However, high SUMF1 expression leads to reduced median survival in ER-negative breast cancer patients. Putative binding sites for miRNAs-106b-5p, 128-3p and 148b-3p were found at 3′-UTR of SUMF1. Since self-assembled branched DNA (bDNA) structures have emerged as a highly efficient strategy for targeting multiple miRNAs simultaneously, we studied the alteration in SUMF1 expression using bDNA nanostructures with a complementary sequence to miRNAs. The findings suggest the involvement of co-regulators and repressors in miRNA-mediated SUMF1 expression in breast cancer cells and reveal the therapeutic potential of SUMF1 in endocrine-related malignancies.

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  • 14.
    Li, Gui
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Iakunkov, Artem
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Boulanger, Nicolas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Lazar, Oana Andreea
    Center for Surface Science and Nanotechnology, University Politehnica of Bucharest, Bucharest, Romania.
    Enachescu, Marius
    Center for Surface Science and Nanotechnology, University Politehnica of Bucharest, Bucharest, Romania.
    Grimm, Alejandro
    Department of Forest Biomaterials and Technology, Biomass Technology Centre, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Talyzin, Aleksandr V.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Activated carbons with extremely high surface area produced from cones, bark and wood using the same procedure2023Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 13, nr 21, s. 14543-14553Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Activated carbons have been previously produced from a huge variety of biomaterials often reporting advantages of using certain precursors. Here we used pine cones, spruce cones, larch cones and a pine bark/wood chip mixture to produce activated carbons in order to verify the influence of the precursor on properties of the final materials. The biochars were converted into activated carbons with extremely high BET surface area up to ∼3500 m2 g−1 (among the highest reported) using identical carbonization and KOH activation procedures. The activated carbons produced from all precursors demonstrated similar specific surface area (SSA), pore size distribution and performance to electrodes in supercapacitors. Activated carbons produced from wood waste appeared to be also very similar to “activated graphene” prepared by the same KOH procedure. Hydrogen sorption of AC follows expected uptake vs. SSA trends and energy storage parameters of supercapacitor electrodes prepared from AC are very similar for all tested precursors. It can be concluded that the type of precursor (biomaterial or reduced graphene oxide) has smaller importance for producing high surface area activated carbons compared to details of carbonization and activation. Nearly all kinds of wood waste provided by the forest industry can possibly be converted into high quality AC suitable for preparation of electrode materials.

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  • 15.
    Martin, Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Biotechnology, Inland Norway University of Applied Sciences, Hamar, Norway.
    Rodríguez, Alejandro
    BioPrEn Group, Instituto Químico para la Energía y el Medioambiente, Chemical Engineering Department, Universidad de Córdoba, Córdoba, Spain.
    Montagnaro, Fabio
    Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant’Angelo, Naples, Italy.
    Introduction to the RSC Advances themed collection Chemistry in Biorefineries2023Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 13, nr 41, s. 28561-28563Artikel i tidskrift (Övrigt vetenskapligt)
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  • 16.
    Mavliutova, Liliia
    et al.
    Department of Biomedical Sciences, Faculty of Health and Society, Malmö University, SE-20506 Malmö, Sweden.
    Munoz Aldeguer, Bruna
    Department of Biomedical Sciences, Faculty of Health and Society, Malmö University, SE-20506 Malmö, Sweden.
    Wiklander, Jesper
    Bioorganic and Biophysical Chemistry Laboratory, Linnaeus University Centre for Biomaterials Chemistry, Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden.
    Wierzbicka, Celina
    Department of Biomedical Sciences, Faculty of Health and Society, Malmö University, SE-20506 Malmö, Sweden.
    Huynh, Chau Minh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Nicholls, Ian A.
    Bioorganic and Biophysical Chemistry Laboratory, Linnaeus University Centre for Biomaterials Chemistry, Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden.
    Irgum, Knut
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sellergren, Börje
    Department of Biomedical Sciences, Faculty of Health and Society, Malmö University, SE-20506 Malmö, Sweden.
    Discrimination between sialic acid linkage modes using sialyllactose-imprinted polymers2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 36, s. 22409-22418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Glycosylation plays an important role in various pathological processes such as cancer. One key alteration in the glycosylation pattern correlated with cancer progression is an increased level as well as changes in the type of sialylation. Developing molecularly-imprinted polymers (MIPs) with high affinity for sialic acid able to distinguish different glycoforms such as sialic acid linkages is an important task which can help in early cancer diagnosis. Sialyllactose with α2,6′vs.α2,3′ sialic acid linkage served as a model trisaccharide template. Boronate chemistry was employed in combination with a library of imidazolium-based monomers targeting the carboxylate group of sialic acid. The influence of counterions of the cationic monomers and template on their interactions was investigated by means of1H NMR titration studies. The highest affinities were afforded using a combination of Br−and Na+counterions of the monomers and template, respectively. The boronate ester formation was confirmed by MS and1H/11B NMR, indicating 1 : 2 stoichiometries between sialyllactoses and boronic acid monomer. Polymers were synthesized in the form of microparticles using boronate and imidazolium monomers. This combinatorial approach afforded MIPs selective for the sialic acid linkages and compatible with an aqueous environment. The molecular recognition properties with respect to saccharide templates and glycosylated targets were reported.

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  • 17. McDonagh, Birgitte H
    et al.
    Singh, Gurvinder
    Bandyopadhyay, Sulalit
    Lystvet, Sina M
    Ryan, Joseph A
    Volden, Sondre
    Kim, Eugene
    Sandvig, Ioanna
    Sandvig, Axel
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap. Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
    Glomm, Wilhelm R
    Controlling the self-assembly and optical properties of gold nanoclusters and gold nanoparticles biomineralized with bovine serum albumin2015Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 5, nr 122, s. 101101-101109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    While the size-dependent optical properties of BSA-stabilized gold nanoclusters are well known, the timedependent growth mechanism remains to be described. Herein, we systematically compare two synthesis methods with and without ascorbic acid, and show that tuning of BSA-stabilized gold nanoclusters (AuNCs) of different sizes can be performed without the aid of an extrinsic reducing agent and with good reproducibility. We also show that adding ascorbic acid yields larger BSA-stabilized gold nanoparticles (AuNPs), and that AuNPs can only form above a threshold gold precursor concentration. Using computed tomography, we describe how these biomineralized AuNPs show size-dependent X-ray attenuation. Growth of BSA-stabilized AuNCs and AuNPs, over a range of gold precursor concentrations, was followed with steady-state fluorescence and UV-vis spectroscopy for one week, constituting the first study of its kind. Based on our results, we propose a mechanism for BSA-stabilization of AuNCs and AuNPs that can further aid in selective growth of discrete AuNCs and AuNPs.

  • 18. Muhammad, Yaseen
    et al.
    Rahman, Ata Ur
    Rashid, Haroon Ur
    Sahibzada, Maria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Subhan, Sidra
    Tong, Zhangfa
    Hydrodesulfurization of dibenzothiophene using Pd-promoted Co–Mo/Al2O3 and Ni–Mo/Al2O3 catalysts coupled with ionic liquids at ambient operating conditions2019Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 9, nr 18, s. 10371-10385Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sulfur compounds in fuel oils are a major source of atmospheric pollution. This study is focused on the hydrodesulfurization (HDS) of dibenzothiophene (DBT) via the coupled application of 0.5 wt% Pd-loaded Co–Mo/Al2O3 and Ni–Mo/Al2O3 catalysts with ionic liquids (ILs) at ambient temperature (120 °C) and pressure (1 MPa H2). The enhanced HDS activity of the solid catalysts coupled with [BMIM]BF4, [(CH3)4N]Cl, [EMIM]AlCl4, and [(n-C8H17)(C4H9)3P]Br was credited to the synergism between hydrogenation by the former and extractive desulfurization and better H2 transport by the latter, which was confirmed by DFT simulation. The Pd-loaded catalysts ranked highest by activity i.e. Pd–Ni–Mo/Al2O3 > Pd–Co–Mo/Al2O3 > Ni–Mo/Al2O3 > Co–Mo/Al2O3. With mild experimental conditions of 1 MPa H2 pressure and 120 °C temperature and an oil : IL ratio of 10 : 3.3, DBT conversion was enhanced from 21% (by blank Ni–Mo/Al2O3) to 70% by Pd–Ni–Mo/Al2O3 coupled with [(n-C8H17)(C4H9)3P]Br. The interaction of polarizable delocalized bonds (in DBT) and van der Waals forces influenced the higher solubility in ILs and hence led to higher DBT conversion. The IL was recycled four times with minimal loss of activity. Fresh and spent catalysts were characterized by FESEM, ICP-MS, EDX, XRD, XPS and BET surface area techniques. GC-MS analysis revealed biphenyl as the major HDS product. This study presents a considerable advance to the classical HDS processes in terms of mild operating conditions, cost-effectiveness, and simplified mechanization, and hence can be envisaged as an alternative approach for fuel oil processing.

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  • 19.
    Nordenström, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Iakunkov, Artem
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sun, Jinhua
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg, Sweden.
    Talyzin, Aleksandr V.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Thermally reduced pillared GO with precisely defined slit pore size2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 12, s. 6831-6839Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Graphene oxide (GO) pillared with tetrakis(4-aminophenyl)methane (TKAM) molecules shows a narrow distribution of pore size, relatively high specific surface area, but it is hydrophilic and electrically not conductive. Analysis of XRD, N2 sorption, XPS, TGA and FTIR data proved that the pillared structure and relatively high surface area (∼350 m2 g−1) are preserved even after thermal reduction of GO pillared with TKAM molecules. Unlike many other organic pillaring molecules, TKAM is stable at temperatures above the point of GO thermal reduction, as demonstrated by TGA. Therefore, gentle annealing results in the formation of reduced graphene oxide (rGO) pillared with TKAM molecules. The TKAM pillared reduced graphene oxide (PrGO/TKAM) is less hydrophilic as found using dynamic vapor sorption (DVS) and more electrically conductive compared to pillared GO, but preserves an increased interlayer-distance of about 12 Å (compared to ∼7.5 Å in pristine GO). Thus we provide one of the first examples of porous rGO pillared with organic molecules and well-defined size of hydrophobic slit pores. Analysis of pore size distribution using nitrogen sorption isotherms demonstrates a single peak for pore size of ∼7 Å, which makes PrGO/TKAM rather promising for membrane and molecular sieve applications.

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  • 20. Nowicki, Janusz
    et al.
    Muszynski, Marcin
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Industrial Chemistry & Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University.
    Ionic liquids derived from organosuperbases: en route to superionic liquids2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 11, s. 9194-9208Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Interest in ionic liquids with guanidine, amidine and other superbasic cations has grown markedly in recent years. The syntheses, characterization and properties of protic and quaternary alkylated salts based on cyclic or acyclic guanidine and amidine derivatives have been described in detail. By modifying the anion or the cation, a wide range of properties of superbasic ionic liquids can be tuned, including viscosity, melting point, density, conductivity, solubility, liquid range, and thermal and hydrolytic stability. They are promising solvents for electrochemical, photovoltaic and various synthetic applications, in particular as specific catalysts. Owing to their specific properties, superbasic ionic liquids can be used in applications of great industrial importance such as CO2, SO2 or COS chemisorption.

  • 21. Privalova, Elena
    et al.
    Rasi, S.
    Mäki-Arvela, P.
    Eränen, K.
    Rintala, D.
    Murzin, D. Yu.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    CO2 capture from biogas: absorbent selection2013Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 3, nr 9, s. 2979-2994Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of proper biogas upgrading technology offers a viable means to utilize biogas in conventional power systems. In this paper, various molecular and ionic solvent systems were evaluated for CO2 removal from biogas in a loop reactor system. The performance of amine solutions, ionic liquids and their mixtures, amino acid salts and solutions blended with piperazine was compared in terms of their CO2 loading capacity. The experimental results revealed that addition of small amounts of piperazine can increase the efficiency of abovementioned solutions on average by 30 vol%. The CO2 capturing capacity of the most promising solvents was in the range of 50-60 L CO2/L absorbent. The regeneration of the solvent mixtures can be challenging since the solvents could loose 16-43 vol% of their initial efficiency upon CO2 release. Ionic liquid [C4mim][acetate] was found to be an efficient VOCs scrubbing media. Moreover, upon use of this ionic liquid, the amount of identified volatile organic compounds (VOCs) in the studied samples was reduced by 65 wt%, while the use of 15 wt% aqueous N-methyldiethanolamine (MDEA) resulted only in 32 wt% reduction in the amount of VOCs.

  • 22. Qin, Danfeng
    et al.
    Xu, Ruiyu
    Shen, Hangjia
    Mamat, Xamxikamar
    Wang, Le
    Gao, Shanshuang
    Wang, Ying
    Yalikun, Nuerbiya
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Zhang, Shiguo
    Yuan, Qunhui
    Li, Yongtao
    Hu, Guangzhi
    Protic salt-based nitrogen-doped mesoporous carbon for simultaneous electrochemical detection of Cd(II) and Pb(II)2017Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 7, nr 59, s. 36929-36934Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nitrogen-doped mesoporous carbon (NMC) derived from a single small-molecule protic salt (p-phenylenediamine bisulfate) is used for sensing toxic heavy metal ions. Using Nafion, bismuth and NMC to anchor the glassy carbon electrode surface, the fabricate electrode shows high sensitivity for detecting Cd(II) and Pb(II). The limits of detection (S/N = 3) are estimated to be 0.3 mu g L-1 for Cd(II) and 0.4 mu g L-1 for Pb(II), respectively, which are 10 and 25 times lower than the maximum acceptable content for drinking water recommended by the WHO. Furthermore, the sensor is successfully used to analyze Cd(II) and Pb(II) in tap-water with high anti-interference capability and good recovery.

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  • 23.
    Sandström, Robin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ekspong, Joakim
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Annamalai, Alagappan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sharifi, Tiva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Department of Materials Science and NanoEngineering, Rice University, Houston, TX, USA.
    Klechikov, Alexey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Fabrication of microporous layer - free hierarchical gas diffusion electrode as a low Pt-loading PEMFC cathode by direct growth of helical carbon nanofibers2018Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 8, nr 72, s. 41566-41574Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Improving interfacial contact between each component in the proton exchange membrane fuel cell (PEMFC) can lead to a significant increase in power density and Pt utilization. In this work, the junction between the catalyst layer and gas diffusion layer (GDL) is greatly enhanced through direct attachment of helical carbon nanofibers, giving rise to a hierarchical structure within the electrical interconnections. The alternative novel GDL is produced by spraying a thin layer of Pd2C60 precursor on commercial carbon paper, followed by chemical vapor deposition growth resulting in a surface morphology of well-attached nanofibers surrounding the microfibers present in the commercial carbon paper. Subsequent solvothermal deposition of platinum nanoparticles allowed evaluation of its suitability as gas diffusion electrode in cathodic H-2/O-2 PEMFC environment. A combination of lowered charge transfer resistance and enhanced Pt-utilization is attributed to its unique wire-like appearance and its robust properties. The fabricated microporous layer - free GDL is suitable for relatively aggressive membrane electrode assembly fabrication procedures and is produced by industrially favorable techniques, rendering it capable of efficiently supporting small amounts of precious metal catalyst nanoparticles in various PEM applications.

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  • 24.
    Sandström, Robin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ekspong, Joakim
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Gracia-Espino, Eduardo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Oxidatively Induced Exposure of Active Surface Area during Microwave Assisted Formation of Pt3Co Nanoparticles for Oxygen Reduction Reaction2019Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 9, nr 31, s. 17979-17987Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The oxygen reduction reaction (ORR), the rate-limiting reaction in proton exchange membrane fuel cells, can efficiently be facilitated by properly manufactured platinum catalysts alloyed with late 3d transition metals. Herein we synthesize a platinum:cobalt nanoparticulate catalyst with a 3:1 atomic ratio by reduction of a dry organometallic precursor blend within a commercial household microwave oven. The formed nanoparticles are simultaneously anchored to a carbon black support that enables large Pt surface area. Two separate microwave treatment steps were employed, where step one constitutes a fast oxidative treatment for revealing active surface area while a reductive secondary annealing treatment promotes a Pt rich surface. The resulting Pt3Co/C catalyst (~3.4 nm) demonstrate an enhanced ORR activity directly attributed to incorporated Co with a specific and mass activity of 704 μA cm-2Pt and 352 A g-1Pt corresponding to an increase by 279 % and 66 % respectively compared to a commercial Pt/C (~1.8 nm) catalyst measured under identical conditions. The method´s simplicity, scalability and novelty is expected to further assist in Pt-Co development and bring the catalyst one step closer toward commercialization and utility in fuel cells.

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  • 25.
    Wu, Guochao
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Shandong Key Lab of Edible Mushroom Technology, School of Agriculture, Ludong University, Yantai, China.
    Alriksson, Björn
    RISE Research Institutes of Sweden AB, Örnsköldsvik, Sweden.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Conditioning of pretreated birch by liquid-liquid organic extractions to improve yeast fermentability and enzymatic digestibility2023Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 13, nr 29, s. 20023-20030Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By-products from hydrothermal pretreatment of lignocellulosic biomass inhibit enzymatic saccharification and microbial fermentation. Three long-chain organic extractants (Alamine 336, Aliquat 336 and Cyanex 921) were compared to two conventional organic solvents (ethyl acetate and xylene) with regard to conditioning of birch wood pretreatment liquid (BWPL) for improved fermentation and saccharification. In the fermentation experiments, extraction with Cyanex 921 resulted in the best ethanol yield, 0.34 ± 0.02 g g−1 on initial fermentable sugars. Extraction with xylene also resulted in a relatively high yield, 0.29 ± 0.02 g g−1, while cultures consisting of untreated BWPL and BWPL treated with the other extractants exhibited no ethanol formation. Aliquat 336 was most efficient with regard to removing by-products, but the residual Aliquat after the extraction was toxic to yeast cells. Enzymatic digestibility increased by 19-33% after extraction with the long-chain organic extractants. The investigation demonstrates that conditioning with long-chain organic extractants has the potential to relieve inhibition of both enzymes and microbes.

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  • 26.
    Zannotti, Marco
    et al.
    Chemistry Interdisciplinary Project, School of Science and Technology, Chemistry Division, University of Camerino, Camerino, Italy; IridES s.r.l., Camerino, Italy.
    Ramasamy, Kesava Priyan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Loggi, Valentina
    Chemistry Interdisciplinary Project, School of Science and Technology, Chemistry Division, University of Camerino, Camerino, Italy.
    Vassallo, Alberto
    School of Biosciences and Veterinary Medicine, Biosciences and Biotechnology Division, University of Camerino, Camerino, Italy.
    Pucciarelli, Sandra
    School of Biosciences and Veterinary Medicine, Biosciences and Biotechnology Division, University of Camerino, Camerino, Italy; IridES s.r.l., Camerino, Italy.
    Giovannetti, Rita
    Chemistry Interdisciplinary Project, School of Science and Technology, Chemistry Division, University of Camerino, Camerino, Italy; IridES s.r.l., Camerino, Italy.
    Hydrocarbon degradation strategy and pyoverdine production using the salt tolerant Antarctic bacterium Marinomonas sp. ef1.2023Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 13, nr 28, s. 19276-19285Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the most concerning environmental problems is represented by petroleum and its derivatives causing contamination of aquatic and underground environments. In this work, the degradation treatment of diesel using Antarctic bacteria is proposed. Marinomonas sp. ef1 is a bacterial strain isolated from a consortium associated with the Antarctic marine ciliate Euplotes focardii. Its potential in the degradation of hydrocarbons commonly present in diesel oil were studied. The bacterial growth was evaluated in culturing conditions that resembled the marine environment with 1% (v/v) of either diesel or biodiesel added; in both cases, Marinomonas sp. ef1 was able to grow. The chemical oxygen demand measured after the incubation of bacteria with diesel decreased, demonstrating the ability of bacteria to use diesel hydrocarbons as a carbon source and degrade them. The metabolic potential of Marinomonas to degrade aromatic compounds was supported by the identification in the genome of sequences encoding various enzymes involved in benzene and naphthalene degradation. Moreover, in the presence of biodiesel, a fluorescent yellow pigment was produced; this was isolated, purified and characterized by UV-vis and fluorescence spectroscopy, leading to its identification as a pyoverdine. These results suggest that Marinomonas sp. ef1 can be used in hydrocarbon bioremediation and in the transformation of these pollutants in molecules of interest.

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  • 27. Zhao, Li Na
    et al.
    Zhang, Tong
    Zhang, Ce
    Wang, Chao
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Morozova-Roche, Ludmilla A.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Chew, Lock Yue
    Mu, Yuguang
    S100A9 induces aggregation-prone conformation in Abeta peptides: a combined experimental and simulation study2013Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 3, nr 46, s. 24081-24089Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inflammation is one of the prominent pathological features in Alzheimer's disease (AD). Recently, there have been various proposed roles of neuroinflammation, such as the driving forces, bystander, byproduct or the neuroprotective response. Notwithstanding these diverse possible mechanisms, experiments have found that S100A9 is one of the pro-inflammatory proteins abundant and over-expressed in the inflammation sites of AD. In this paper, we examine the role of S100A9 in the oligomerization process of A beta peptides by means of replica exchange molecular dynamics simulation and experimental investigations. Our experiments, based on atomic force microscopy and Thioflavin T spectroscopic assays, have clearly indicated that the close interaction between S100A9 and A beta has significantly enhanced the A beta oligomerization. In line with the experimental observation, our simulation studies have revealed that the pro-inflammatory S100A9 protein interacts with the A beta peptides directly, mainly through hydrophobic interactions with the A beta central hydrophobic core region. In addition, the formation of hydrogen bonds between the residues of the S100A9 homodimer and the two ends of the A beta peptides is found to cause a straightening of the A beta(12-24) peptides. A more straight A beta(12-24) peptide with a higher beta-content then may function as a template to induce the folding of new incoming A beta peptides, which leads to the formation of aggregation-prone oligomers.

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