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  • 1.
    Aguilar-Sanchez, Andrea
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Jalvo, Blanca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Mautner, Andreas
    Rissanen, Ville
    Kontturi, Katri S.
    Abdelhamid, Hani Nasser
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Tammelin, Tekla
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Charged ultrafiltration membranes based on TEMPO-oxidized cellulose nanofibrils/poly(vinyl alcohol) antifouling coating2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 12, s. 6859-6868Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study reports the potential of TEMPO-oxidized cellulose nanofibrils (T-CNF)/poly(vinyl alcohol) (PVA) coatings to develop functionalized membranes in the ultrafiltration regime with outstanding antifouling performance and dimensional/pH stability. PVA acts as an anchoring phase interacting with the polyethersulfone (PES) substrate and stabilizing for the hygroscopic T-CNF via crosslinking. The T-CNF/PVA coated PES membranes showed a nano-textured surface, a change in the surface charge, and improved mechanical properties compared to the original PES substrate. A low reduction (4%) in permeance was observed for the coated membranes, attributable to the nanometric coating thickness, surface charge, and hydrophilic nature of the coated layer. The coated membranes exhibited charge specific adsorption driven by electrostatic interaction combined with rejection due to size exclusion (MWCO 530 kDa that correspond to a size of similar to 35-40 nm). Furthermore, a significant reduction in organic fouling and biofouling was found for T-CNF/PVA coated membranes when exposed to BSA and E. coli. The results demonstrate the potential of simple modifications using nanocellulose to manipulate the pore structure and surface chemistry of commercially available membranes without compromising on permeability and mechanical stability.

  • 2.
    Akhtar, Farid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Luleå University of Technology, Sweden.
    Keshavarzi, Neda
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Shakarova, Dilshod
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Cheung, Ocean
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Hedin, Niklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Aluminophosphate monoliths with high CO2-over-N2 selectivity and CO2 capture capacity2014Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 4, nr 99, s. 55877-55883Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monoliths of microporous aluminophosphates (AlPO4-17 and AlPO4-53) were structured by binder-freepulsed current processing. Such monoliths could be important for carbon capture from flue gas. TheAlPO4-17 and AlPO4-53 monoliths exhibited a tensile strength of 1.0 MPa and a CO2 adsorption capacityof 2.5 mmol g1 and 1.6 mmol g1, respectively at 101 kPa and 0 C. Analyses of single component CO2and N2 adsorption data indicated that the AlPO4-53 monoliths had an extraordinarily high CO2-over-N2selectivity from a binary gas mixture of 15 mol% CO2 and 85 mol% N2. The estimated CO2 capturecapacity of AlPO4-17 and AlPO4-53 monoliths in a typical pressure swing adsorption (PSA) process at 20C was higher than that of the commonly used zeolite 13X granules. Under cyclic sorption conditions,AlPO4-17 and AlPO4-53 monoliths were regenerated by lowering the pressure of CO2. Regeneration wasdone without application of heat, which would regenerate them to their full capacity for CO2 adsorption.

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    Aluminophosphate monoliths with high CO2-over- N2 selectivity and CO2 capture capacity
  • 3. Alanis, Andrés
    et al.
    Hernández Valdés, Josué
    Maria Guadalupe, Neira-Velázquez
    Lopez, Ricardo
    Mendoza, Ricardo
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Diaz de León, Ramón
    Valencia, Luis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Plasma surface-modification of cellulose nanocrystals: a green alternative towards mechanical reinforcement of ABS2019Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 9, nr 30, s. 17417-17424Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article proposes a strategy to functionalize cellulose nanocrystals by means of plasma-surface modification utilizing monomers of different nature: caprolactone, styrene and farnesene. The surface characteristics of the nanocrystals were studied by different techniques including XPS, FTIR and STEM, demonstrating that this technique allows a successful functionalization, yielding homogenous functionalization which does not alter the rod-like shape of the nanocrystals, and therefore their anisotropic behavior. We have furthermore studied the employment of the modified nanocrystals as reinforcement additive of ABS, which significantly enhanced the impact resistance of the thermoplastic, which could have great implications for industrial applications.

  • 4.
    B. Brant Carvalho, Paulo H.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Moraes, Pedro Ivo R.
    Leitão, Alexandre A.
    Andersson, Ove
    Tulk, Chris A.
    Molaison, Jamie
    Lyubartsev, Alexander P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Häussermann, Ulrich
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    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, Fdm, 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.

  • 5. Bassyouni, Fatma A.
    et al.
    Abu-Baker, Sherifa M.
    Mahmoud, Khaled
    Moharam, Maysa
    El-Nakkady, Sally S.
    Rehim, Mohamed Abdel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för analytisk kemi.
    Synthesis and biological evaluation of some new triazolo[1,5-a]quinoline derivatives as anticancer and antimicrobial agents2014Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 4, nr 46, s. 24131-24141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present study, versatile multifunctional unreported triazolo[1,5-a]quinoline derivatives were prepared. Compounds 1-19 were synthesized by adopting appropriate synthetic routes and were pharmacologically evaluated for their in vitro anticancer activity against human cancer cell lines: hepatocellular liver carcinoma (HEPG2) and Caucasian breast adenocarcinoma (MCF-7), in addition to their antibacterial and antifungal activities. Compound 4 demonstrated strong inhibitory effects against breast cancer (MCF-7), whereas compounds 8 and 19 exhibited moderate activity against breast carcinoma cell line MCF-7. Compounds 16 and 19 gave moderate activity against liver carcinoma cell line HEPG2. The antimicrobial activity of the prepared compounds was tested against bacteria and fungi. Among them, the results of antimicrobial activity indicated that compounds 4, 9, 11, 13, 15, 17, 18 and 19 were the most active compounds. Compound 4 exhibited strong activity against Fusarium sp., whereas compounds 9, 11, 15, 17, 18 and 19 showed high activity against Escherichia coli. More specifically, compound 17 displayed a high inhibitory effect against Bacillus cereus, Escherichia coli and Rhizoctonia sp.

  • 6.
    Bermejo Gómez, Antonio
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Holmberg, Pär
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martin-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalyzed redox isomerization of codeine and morphine in water2014Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 4, nr 74, s. 39519-39522Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A water-soluble rhodium complex formed from commercially available [Rh(COD)(CH3CN)(2)]BF4 and 1,3,5-triaza-7-phosphaadamantane (PTA) catalyzes the isomerization of both codeine and morphine into hydrocodone and hydromorphone with very high efficiency. The reaction is performed in water, allowing isolation of the final products by simple filtration, which results in very high isolated yields. The reactions can be easily scaled up to 100 g.

    Ladda ner fulltext (pdf)
    fulltext
  • 7. Blahut, Jan
    et al.
    Benda, Ladislav
    Lejeune, Arthur L.
    Sanders, Kevin J.
    Burcher, Benjamin
    Jeanneau, Erwann
    Proriol, David
    Catita, Leonor
    Breuil, Pierre-Alain R.
    Quoineaud, Anne-Agathe
    Pell, Andrew J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Université de Lyon, France.
    Pintacuda, Guido
    Proton-detected fast-magic-angle spinning NMR of paramagnetic inorganic solids2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 47, s. 29870-29876Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fast (60 kHz) magic angle spinning solid-state NMR allows very sensitive proton detection in highly paramagnetic organometallic powders. We showcase this technique with the complete assignment of H-1 and C-13 resonances in a high-spin Fe(ii) polymerisation catalyst with less than 2 mg of sample at natural abundance.

  • 8.
    Cheung, Ocean
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Hedin, Niklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zeolites and related sorbents with narrow pores for CO2 separation from flue gas2014Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 4, nr 28, s. 14480-14494Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Adsorbents with small pores are especially relevant for capturing carbon dioxide at large emission sources. Such sorbents could be used potentially to reduce the energy demands for separating carbon dioxide from flue gas as compared with today's technologies. Here, we review the literature for crystalline, inorganic, and potentially inexpensive adsorbents. A number of different adsorbents with narrow pore openings are compared.

  • 9. Cheung, Ocean
    et al.
    Zhang, Peng
    Frykstrand, Sara
    Zheng, Haoquan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Yang, Taimin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Sommariva, Marco
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Strømme, Maria
    Nanostructure and pore size control of template-free synthesised mesoporous magnesium carbonate2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 78, s. 74241-74249Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure of mesoporous magnesium carbonate (MMC) first presented in 2013 is investigated using a bottom-up approach. MMC is found to be built from the aggregation of nanoparticles of amorphous MgCO3 and MgO with a coating of amorphous MgCO3. The nanoparticles have dimensions of approximately 2-5 nm as observed using transmission electron microscopy and the aggregation of the particles creates the pore structure of MMC. We further show that the average pore diameter of MMC can be controlled by varying the temperature during the powder formation process and demonstrate that altering the pore size opens the possibility to tune the amorphous phase stabilisation properties that MMC exerts on poorly soluble drug compounds. Specifically, we show the loading and release of the antifungal drug itraconazole using MMC as a drug carrier.

  • 10. Coroaba, Adina
    et al.
    Isac, Dragos-Lucian
    Al-Matarneh, Cristina
    Vasiliu, Tudor
    Ibanescu, Sorin-Alexandru
    Zonda, Radu
    Ardeleanu, Rodinel
    Neamtu, Andrei
    Timpu, Daniel
    Nicolescu, Alina
    Mocci, Francesca
    Maier, Stelian S.
    Laaksonen, Aatto
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Petru Poni Institute of Macromolecular Chemistry, Romania.
    Médard Abadie, Marc Jean
    Pinteala, Mariana
    Probing the supramolecular features via π–π interaction of a di-iminopyrene-di-benzo-18-crown-6-ether compound: experimental and theoretical study2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 63, s. 38304-38315Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel DPyDB-CN-18C6 compound was synthesised by linking a pyrene moiety to each phenyl group of dibenzo-18-crown-6-ether, the crown ether, through –HCN– bonds and characterized by FTIR, 1H-NMR, 13C-NMR, TGA, and DSC techniques. The quantitative 13C-NMR analysis revealed the presence of two position isomers. The electronic structure of the DPyDB-CN-18C6 molecule was characterized by UV-vis and fluorescence spectroscopies in four solvents with different polarities to observe particular behavior of isomers, as well as to demonstrate a possible non-bonding chemical association (such as ground- and excited-state associations, namely, to probe if there were forming dimers/excimers). The interpretation of the electronic structure was realized through QM calculations. The TD-CAM-B3LYP functional, at the 6-311+G(d,p) basis set, indicated the presence of predominant π → π* and mixed π → π* + n → π* transitions, in line with the UV-vis experimental data. Even though DPyDB-CN-18C6 computational studies revealed a π-extended conjugation effect with predominantly π → π* transitions, thorough fluorescence analysis was observed a weak emission, as an effect of PET and ACQ. In particular, the WAXD analysis of powder and thin films obtained from n-hexane, 1,2-dichloroethane, and ethanol indicated an amorphous organization, whereas from toluene a smectic ordering was obtained. These results were correlated with MD simulation, and it was observed that the molecular geometry of DPyDB-CN-18C6 molecule played a defining role in the pyrene stacking arrangement.

  • 11. Deiana, Luca
    et al.
    Rafi, Abdolrahim A.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Cordova, Armando
    Subtilisin integrated artificial plant cell walls as heterogeneous catalysts for asymmetric synthesis of (S)-amides2023Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 13, nr 29, s. 19975-19980Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Subtilisin integrated artificial plant-cell walls (APCWs) were fabricated by self-assembly using cellulose or nanocellulose as the main component. The resulting APCW catalysts are excellent heterogeneous catalysts for the asymmetric synthesis of (S)-amides. This was demonstrated by the APCW-catalyzed kinetic resolution of several racemic primary amines to give the corresponding (S)-amides in high yields with excellent enantioselectivity. The APCW catalyst can be recycled for multiple reaction cycles without loss of enantioselectivity. The assembled APCW catalyst was also able to cooperate with a homogeneous organoruthenium complex, which allowed for the co-catalytic dynamic kinetic resolution (DKR) of a racemic primary amine to give the corresponding (S)-amide in high yield. The APCW/Ru co-catalysis constitutes the first examples of DKR of chiral primary amines when subtilisin is used as a co-catalyst.

  • 12. Doyle, Bradley
    et al.
    Madden, Leigh A.
    Pamme, Nicole
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). University of Hull, UK.
    Jones, Huw S.
    Immobilised-enzyme microreactors for the identification and synthesis of conjugated drug metabolites2023Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 13, nr 40, s. 27696-27704Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The study of naturally circulating drug metabolites has been a focus of interest, since these metabolites may have different therapeutic and toxicological effects compared to the parent drug. The synthesis of metabolites outside of the human body is vital in order to conduct studies into the pharmacological activities of drugs and bioactive compounds. Current synthesis methods require significant purification and separation efforts or do not provide sufficient quantities for use in pharmacology experiments. Thus, there is a need for simple methods yielding high conversions whilst bypassing the requirement for a separation. Here we have developed and optimised flow chemistry methods in glass microfluidic reactors utilising surface-immobilised enzymes for sulfonation (SULT1a1) and glucuronidation (UGT1a1). Conversion occurs in flow, the precursor and co-factor are pumped through the device, react with the immobilised enzymes and the product is then simply collected at the outlet with no separation from a complex biological matrix required. Conversion only occurred when both the correct co-factor and enzyme were present within the microfluidic system. Yields of 0.97 & PLUSMN; 0.26 & mu;g were obtained from the conversion of resorufin into resorufin sulfate over 2 h with the SULT1a1 enzyme and 0.47 & mu;g of resorufin glucuronide over 4 h for UGT1a1. This was demonstrated to be significantly more than static test tube reactions at 0.22 & mu;g (SULT1a1) and 0.19 & mu;g (UGT1a1) over 4 h. With scaling out and parallelising, useable quantities of hundreds of micrograms for use in pharmacology studies can be synthesised simply. On-chip continuous-flow synthesis of metabolites from glucuronidation and sulfonation reactions to enable synthesis of analytical standards and study drug metabolism.

  • 13. El-Seedi, Hesham R.
    et al.
    El-Shabasy, Rehan M.
    Khalifa, Shaden A. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för molekylär biovetenskap, Wenner-Grens institut. Karolinska University Hospital, Sweden.
    Saeed, Aamer
    Shah, Afzal
    Shah, Raza
    Iftikhar, Faiza Jan
    Abdel-Daim, Mohamed M.
    Omri, Abdelfatteh
    Hajrahand, Nahid H.
    Sabir, Jamal S. M.
    Zou, Xiaobo
    Halabi, Mohammed F.
    Sarhan, Wessam
    Guo, Weisheng
    Metal nanoparticles fabricated by green chemistry using natural extracts: biosynthesis, mechanisms, and applications2019Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 9, nr 42, s. 24539-24559Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Nanoparticles (NPs) are new inspiring clinical targets that have emerged from persistent efforts with unique properties and diverse applications. However, the main methods currently utilized in their production are not environmentally friendly. With the aim of promoting a green approach for the synthesis of NPs, this review describes eco-friendly methods for the preparation of biogenic NPs and the known mechanisms for their biosynthesis. Natural plant extracts contain many different secondary metabolites and biomolecules, including flavonoids, alkaloids, terpenoids, phenolic compounds and enzymes. Secondary metabolites can enable the reduction of metal ions to NPs in eco-friendly one-step synthetic processes. Moreover, the green synthesis of NPs using plant extracts often obviates the need for stabilizing and capping agents and yields biologically active shape- and size-dependent products. Herein, we review the formation of metallic NPs induced by natural extracts and list the plant extracts used in the synthesis of NPs. In addition, the use of bacterial and fungal extracts in the synthesis of NPs is highlighted, and the parameters that influence the rate of particle production, size, and morphology are discussed. Finally, the importance and uniqueness of NP-based products are illustrated, and their commercial applications in various fields are briefly featured.

  • 14.
    Ermilova, Inna
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Lyubartsev, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Modelling of interactions between Aβ(25-35) peptide and phospholipid bilayers: effects of cholesterol and lipid saturation2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 7, s. 3902-3915Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aggregation of amyloid beta (Aβ) peptides in neuronal membranes is a known promoter of Alzheimer’s disease. To gain insight into the molecular details of Aβ peptide aggregation and its effect on model neuronal membranes, we carried out molecular dynamics simulations of the Aβ(25–35) fragment of the amyloid precursor protein in phospholipid bilayers composed of either fully saturated or highly unsaturated lipids, in the presence or absence of cholesterol. It was found that the peptide does not penetrate through any of the considered membranes, but can reside in the headgroup region and upper part of the lipid tails showing a clear preference to a polyunsaturated cholesterol-free membrane. Due to the ordering and condensing effect upon addition of cholesterol, membranes become more rigid facilitating peptide aggregation on the surface. Except for the case of the cholesterol-free saturated lipid bilayer, the peptides have a small effect on the membrane structure and ordering. It was also found that the most “active” amino-acid for peptide–lipid and peptide–cholesterol interaction is methionine-35, followed by asparagine-27 and serine-26, which form hydrogen bonds between peptides and polar atoms of lipid headgroups. These amino acids are also primarily responsible for peptide aggregation. This work will be relevant for designing strategies to develop drugs to combat Alzheimer’s disease.

  • 15. Esquivel-Pena, Vicente
    et al.
    Guccini, Valentina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). KTH Royal Institute of Technology, Sweden .
    Kumar, Sugam
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Salazar-Alvarez, German
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). KTH Royal Institute of Technology, Sweden .
    de San Miguel, Eduardo Rodriguez
    de Gyves, Josefina
    Hybrids based on borate-functionalized cellulose nanofibers and noble-metal nanoparticles as sustainable catalysts for environmental applications2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 21, s. 12460-12468Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polymeric supports from renewable resources such as cellulose nanomaterials are having a direct impact on the development of heterogenous sustainable catalysts. Recently, to increase the potentiality of these materials, research has been oriented towards novel functionalization possibilities. In this study, to increase the stability of cellulose nanofiber films as catalytic supports, by limiting the solubility in water, we report the synthesis of new hybrid catalysts (HC) based on silver, gold, and platinum nanoparticles, and the corresponding bimetallic nanoparticles, supported on cellulose nanofibers (CNFs) cross-linked with borate ions. The catalysts were prepared from metal precursors reduced by the CNFs in an aqueous suspension. Metal nanoparticles supported on CNFs with a spherical shape and a mean size of 9 nm were confirmed by TEM, XRD, and SAXS. Functionalized films of HC-CNFs were obtained by adding a borate solution as a cross-linking agent. Solid-state B-11 NMR of films with different cross-linking degrees evidenced the presence of four different boron species of which the bis-chelate is responsible for the cross-linking of the CNFs. Also, it may be concluded that the bis-chelate and the mono-chelates modify the microstructure of the film increasing the water uptake and enhancing the catalytic activity in the reduction of 4-nitrophenol.

  • 16. Fan, Junpeng
    et al.
    Ekspong, Joakim
    Ashok, Anumol
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Koroidov, Sergey
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Gracia-Espino, Eduardo
    Solid-state synthesis of few-layer cobalt-doped MoS(2)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-MoS(2)flakes (similar to 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-MoS(2)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-MoS(2)with predominant CoMoS phase, excellent HER activity, and operational stability.

  • 17.
    Fijoł, Natalia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Abdelhamid, Hani Nasser
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Assiut University, Egypt.
    Pillai, Binsi
    Hall, Stephen A.
    Thomas, Nebu
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    3D-printed monolithic biofilters based on a polylactic acid (PLA) - hydroxyapatite (HAp) composite for heavy metal removal from an aqueous medium2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 51, s. 32408-32418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High flux, monolithic water purification filters based on polylactic acid (PLA) functionalised with fish scale extracted hydroxyapatite (HAp) were prepared by solvent-assisted blending and thermally induced phase separation (TIPS), followed by twin-screw extrusion into filaments and processed via three-dimensional (3D) printing. The printed filters with consistent pore geometry and channel interconnectivity as well as homogenous distribution of HAp in the PLA matrix showed adsorption capabilities towards heavy metals i.e. cadmium (Cd) and lead (Pb) with maximum adsorption capacity of 112.1 mg gHAp−1 and 360.5 mg gHAp−1 for the metal salt of Pb and Cd, respectively. The adsorption was found to be driven by a combination of ion exchange, dissolution and precipitation on HAp and surface complexation.

  • 18. Francois, Camille
    et al.
    Pourchet, Sylvie
    Boni, Gilles
    Fontaine, Stephane
    Gaillard, Yves
    Placet, Vincent
    Galkin, Maxim V.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Orebom, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Samec, Joseph
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Plasseraud, Laurent
    Diglycidylether of iso-eugenol: a suitable lignin-derived synthon for epoxy thermoset applications2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 73, s. 68732-68738Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel lignin-based synthon, diglycidylether of iso-eugenol (DGE-isoEu) is used as a prepolymer for the preparation of thermosetting resins. DGE-isoEu is synthesized in a two-step procedure with a satisfactory yield from bio-based iso-eugenol (isoEu, 2-methoxy-4-(1-propenyl)phenol) catalytically fragmented from lignin in an organosolv process. DGE-isoEu was fully characterized by NMR, MS and FTIR. Curing of the DGE-isoEu monomer has then been investigated in the presence of several carboxylic acid derivatives hardeners. The thermal and mechanical properties of each material were recorded showing, in particular, a high T-g and instantaneous modulus values in the range of 78-120 degrees C and 4.6-5.5 GPa, respectively. The lignin derived new materials give very attractive thermo-mechanical properties comparable to that of common BPA-containing epoxy resins.

  • 19. González-Zapata, José Luis
    et al.
    Enríquez-Medrano, Francisco Javier
    López González, Héctor Ricardo
    Revilla-Vázquez, Javier
    Mendoza Carrizales, Ricardo
    Georgouvelas, Dimitrios
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Valencia, Luis
    Díaz de León Gómez, Ramón Enrique
    Introducing random bio-terpene segments to high cis-polybutadiene: making elastomeric materials more sustainable2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 72, s. 44096-44102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we explore the statistical copolymerization of 1,3-butadiene with the terpenic monomers myrcene and farnesene, carried out via coordination polymerization using a neodymium-based ternary catalytic system. The resultant copolymers, poly(butadiene-co-myrcene) and poly(butadiene-co-farnesene), were synthesized at different monomer ratios, elucidating the influence of the bio-based monomer content over the kinetic variables, molecular and thermal properties, and the reactivity constants (Fineman-Ross and Kelen-Tudos methods) of the resultant copolymers. The results indicate that through the herein employed conditions, it is possible to obtain more sustainable high-cis (approximate to 95%) polybutadiene elastomers with random and tunable content of bio-based monomer. Moreover, the polymers exhibit fairly high molecular weights and a rather low dispersity index. Upon copolymerization, the T-g of high-cis PB can be shifted from -106 to -75 degrees C (farnesene) or -107 to -64 degrees C (myrcene), without altering the microstructure control. This work contributes to the development of more environmentally friendly elastomers, to form green rubber materials.

  • 20.
    Guo, Hua
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Jaworski, Aleksander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Ma, Zili
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). RWTH Aachen University, Germany.
    Slabon, Adam
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bacsik, Zoltan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Nedumkandathil, Reji
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Häussermann, Ulrich
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Trapping of different stages of BaTiO3 reduction with LiH2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 58, s. 35356-35365Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigated the hydride reduction of tetragonal BaTiO3 using LiH. The reactions employed molar H : BaTiO3 ratios of 1.2, 3, and 10 and variable temperatures up to 700 °C. The air-stable reduced products were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy, thermogravimetric analysis (TGA), X-ray fluorescence (XRF), and 1H magic-angle spinning (MAS) NMR spectroscopy. Effective reduction, as indicated by the formation of dark blue to black colored, cubic-phased, products was observed at temperatures as low as 300 °C. The product obtained at 300 °C corresponded to oxyhydride BaTiO∼2.9H∼0.1, whereas reduction at higher temperatures resulted in simultaneous O defect formation, BaTiO2.9−xH0.1□x, and eventually – at temperatures above 450 °C – to samples void of hydridic H. Concomitantly, the particles of samples reduced at high temperatures (500–600 °C) display substantial surface alteration, which is interpreted as the formation of a TiOx(OH)y shell, and sintering. Diffuse reflectance UV-VIS spectroscopy shows broad absorption in the VIS-NIR region, which is indicative of the presence of n-type free charge carriers. The size of the intrinsic band gap (∼3.2 eV) appears only slightly altered. Mott–Schottky measurements confirm the n-type conductivity and reveal shifts of the conduction band edge in the LiH reduced samples. Thus LiH appears as a versatile reagent to produce various distinct forms of reduced BaTiO3 with tailored electronic properties.

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  • 21.
    Hadi, Seyed Ehsan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Yeprem, H. Aygül
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Yıldız Technical University, Turkey.
    Åhl, Agnes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Morsali, Mohammad
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Kapuscinski, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Kriechbaum, Konstantin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Sipponen, Mika H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Highly magnetic hybrid foams based on aligned tannic acid-coated iron oxide nanoparticles and TEMPO-oxidized cellulose nanofibers2023Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 13, nr 20, s. 13919-13927Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lightweight iron oxide nanoparticle (IONP)/TEMPO-oxidized cellulose nanofibril (TOCNF) hybrid foams with an anisotropic structure and a high IONP content were produced using magnetic field-enhanced unidirectional ice-templating. Coating the IONP with tannic acid (TA) improved the processability, the mechanical performance, and the thermal stability of the hybrid foams. Increasing the IONP content (and density) increased the Young's modulus and toughness probed in compression, and hybrid foams with the highest IONP content were relatively flexible and could recover 14% axial compression. Application of a magnetic field in the freezing direction resulted in the formation of IONP chains that decorated the foam walls and the foams displayed a higher magnetization saturation, remanence, and coercivity compared to the ice-templated hybrid foams. The hybrid foam with an IONP content of 87% displayed a saturation magnetization of 83.2 emu g−1, which is 95% of the value for bulk magnetite. Highly magnetic hybrid foams are of potential interest for environmental remediation, energy storage, and electromagnetic interference shielding.

  • 22. Istomin, S. Ya.
    et al.
    Karakulina, O. M.
    Rozova, M. G.
    Kazakov, S. M.
    Gippius, A. A.
    Antipov, E. V.
    Bobrikov, I. A.
    Balagurov, A. M.
    Tsirlin, A. A.
    Michau, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Biendicho, Jordi Jacas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Svensson, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Tuning the high-temperature properties of Pr2NiO4+delta by simultaneous Pr- and Ni-cation replacement2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 40, s. 33951-33958Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Novel Pr2-xSrxNi1-xCoxO4 +/-delta (x = 0.25; 0.5; 0.75) oxides with the tetragonal K2NiF4-type structure have been prepared. Room-temperature neutron powder diffraction (NPD) study of x = 0.25 and 0.75 phases together with iodometric titration results have shown the formation of hyperstoichiometric oxide for x = 0.25 (delta = 0.09(2)) and a stoichiometric one for x = 0.75. High-temperature X-ray powder diffraction (HT XRPD) showed substantial anisotropy of the thermal expansion coefficient (TEC) along the a-and c-axis of the crystal structure, which increases with increasing the Co content from TEC(c)/TEC(a) = 2.4 (x = 0.25) to 4.3 (x = 0.75). High-temperature NPD (HT NPD) study of the x = 0.75 sample reveals that a very high expansion of the axial (Ni/Co)-O bonds (75.7 ppm K-1 in comparison with 9.1 ppm K-1 for equatorial ones) is responsible for such behaviour, and is caused by a temperature-induced transition between low- and high-spin states of Co3+. This scenario has been confirmed by high-temperature magnetization measurements on a series of Pr2-xSrxNi1-xCoxO4 +/-delta samples. For compositions with high Ni content (x = 0.25 and 0.5) we synthesised K2NiF4-type oxides Pr2-x-ySrx+y(Ni1-xCox)O-4 +/-delta, y = 0.0-0.75 (x = 0.25); y = 0.0-0.5 (x = 0.5). The studies of the TEC, high-temperature electrical conductivity in air, chemical stability of the prepared compounds in oxygen and toward interaction with Ce2-xGdxO2-x/2 (GDC) at high temperatures reveal optimal behaviour of Pr1.35Sr0.65Ni0.75Co0.25O4+delta. This compound shows stability in oxygen at 900 degrees C and does not react with GDC at least up to 1200 degrees C. It features low TEC of 13 ppm K-1 and high-temperature electrical conductivity in air of 280 S cm(-1) at 900 degrees C, thus representing a promising composition for use as a cathode material in intermediate temperature solid oxide fuel cells (IT-SOFC).

  • 23. Jesús Naveja, J.
    et al.
    Norinder, Ulf
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap. Swetox, Karolinska Institutet, Sweden.
    Mucs, Daniel
    López-López, Edgar
    Medina-Franco, Jose L.
    Chemical space, diversity and activity landscape analysis of estrogen receptor binders2018Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 8, nr 67, s. 38229-38237Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding the structure-activity relationships (SAR) of endocrine-disrupting chemicals has a major importance in toxicology. Despite the fact that classifiers and predictive models have been developed for estrogens for the past 20 years, to the best of our knowledge, there are no studies of their activity landscape or the identification of activity cliffs. Herein, we report the first SAR of a public dataset of 121 chemicals with reported estrogen receptor binding affinities using activity landscape modeling. To this end, we conducted a systematic quantitative and visual analysis of the chemical space of the 121 chemicals. The global diversity of the dataset was characterized by means of Consensus Diversity Plot, a recently developed method. Adding pairwise activity difference information to the chemical space gave rise to the activity landscape of the data set uncovering a heterogeneous SAR, in particular for some structural classes. At least eight compounds were identified with high propensity to form activity cliffs. The findings of this work further expand the current knowledge of the underlying SAR of estrogenic compounds and can be the starting point to develop novel and potentially improved predictive models.

  • 24. Johansson, Mikael P.
    et al.
    Niederegger, Lukas
    Rauhalahti, Markus
    Hess, Corinna R.
    Kaila, Ville R. I.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik. Technical University of Munich (TUM), Germany.
    Dispersion forces drive water oxidation in molecular ruthenium catalysts2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 1, s. 425-432Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rational design of artificial water-splitting catalysts is central for developing new sustainable energy technology. However, the catalytic efficiency of the natural light-driven water-splitting enzyme, photosystem II, has been remarkably difficult to achieve artificially. Here we study the molecular mechanism of ruthenium-based molecular catalysts by integrating quantum chemical calculations with inorganic synthesis and functional studies. By employing correlated ab initio calculations, we show that the thermodynamic driving force for the catalysis is obtained by modulation of pi-stacking dispersion interactions within the catalytically active dimer core, supporting recently suggested mechanistic principles of Ru-based water-splitting catalysts. The dioxygen bond forms in a semi-concerted radical coupling mechanism, similar to the suggested water-splitting mechanism in photosystem II. By rationally tuning the dispersion effects, we design a new catalyst with a low activation barrier for the water-splitting. The catalytic principles are probed by synthesis, structural, and electrochemical characterization of the new catalyst, supporting enhanced water-splitting activity under the examined conditions. Our combined findings show that modulation of dispersive interactions provides a rational catalyst design principle for controlling challenging chemistries.

  • 25.
    Jose, Jiya
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Mahatma Gandhi University, India.
    Sultan, Sahar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Kalarikkal, Nandakumar
    Thomas, Sabu
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Fabrication and functionalization of 3D-printed soft and hard scaffolds with growth factors for enhanced bioactivity2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 62, s. 37928-37937Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Strategies to improve the acceptance of scaffolds by the body is crucial in tissue engineering (TE) which requires tailoring of the pore structure, mechanical properties and surface characteristics of the scaffolds. In the current study we used a 3-dimensional (3D) printing technique to tailor the pore structure and mechanical properties of (i) nanocellulose based hydrogel scaffolds for soft tissue engineering and (ii) poly lactic acid (PLA) based scaffolds for hard tissue engineering in combination with surface treatment by protein conjugation for tuning the scaffold bioactivity. Dopamine coating of the scaffolds enhanced the hydrophilicity and their capability to bind bioactive molecules such as fibroblast growth factor (FGF-18) for soft TE scaffolds and arginyl glycyl aspartic acid (RGD) peptide for hard TE scaffolds, which was confirmed using MALDI-TOFs. This functionalization approach enhanced the performance of the scaffolds and provided antimicrobial activity indicating that these scaffolds can be used for cartilage or bone regeneration applications. Blood compatibility studies revealed that both the materials were compatible with human red blood cells. Significant enhancement of cell attachment and proliferation confirmed the bioactivity of growth factor functionalized 3D printed soft and hard tissues. This approach of combining 3D printing with biological tuning of the interface is expected to significantly advance the development of biomedical materials related to soft and hard tissue engineering.

  • 26. Karim, Zoheb
    et al.
    Hakalahti, Minna
    Tammelin, Tekla
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Luleå University of Technology, Sweden.
    In situ TEMPO surface functionalization of nanocellulose membranes for enhanced adsorption of metal ions from aqueous medium2017Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 7, nr 9, s. 5232-5241Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current work demonstrates an innovative approach to develop nanocellulose based membranes with high water permeability, mechanical stability and high functionality via (1) tailoring the composition of the support layer of sludge microfibers/cellulose nanofibers (CNFSL) and (2) in situ TEMPO functionalization of the thin functional layer of cellulose nanocrystals (CNCBE) to enhance the metal ion adsorption capacity. SEM studies showed a porous network structure of the cellulose support layer and a denser functional layer with CNCBE embedded within gelatin matrix. AFM studies indicated the presence of a nanoscaled coating and increased roughness of membranes surface after TEMPO modification whereas FT-IR and conductometric titration confirmed the introduction of carboxyl groups upon TEMPO oxidation. The contact angle measurement results showed improved hydrophilic nature of membranes after in situ TEMPO functionalization. High networking potential of CNFSL made the membrane support layer tighter with a concomitant decrease in the average pore size from 6.5 to 2.0 mm. The coating with CNCBE further decreased the average pore size to 0.78 and 0.58 mm for S/CNCBE and S-CNFSL/CNCBE, respectively. In parallel, a drastic decrease in water flux (8000 to 90 L MPa-1 h(-1) m(-2)) after coating with CNCBE was recorded but interestingly in situ functionalization of top CNCBE layer did not affect water flux significantly. The increase in adsorption capacity of approximate to 1.3 and approximate to 1.2 fold was achieved for Cu(II) and Fe(II)/Fe(III), respectively after in situ TEMPO functionalization of membranes. Biodegradation study confirmed the stability of layered membranes in model wastewater and a complete degradation of membranes was recorded after 15 days in soil.

  • 27. Karim, Zoheb
    et al.
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Luleå University of Technology, Sweden.
    Kokol, Vanja
    Wei, Jiang
    Grahn, Mattias
    High-flux affinity membranes based on cellulose nanocomposites for removal of heavy metal ions from industrial effluents2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 25, s. 20644-20653Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fully biobased affinity membrane processing and its application in the removal of heavy metal ions from mirror industry effluents were successfully demonstrated; indicating the potential use of these membranes in point-of-use or point-of-entry water cleaning products that are cheap, environmentally friendly and efficient. Layered cellulose nanocomposite membranes were fabricated using cellulose microfiber sludge as a support layer and cellulose nanocrystals (CNCSL, CNCBE or PCNCSL) in a gelatin matrix as the functional layer. Scanning electron microscopy (SEM) studies revealed the bi-layered morphology of the membrane and well-individualized nanocelluloses in the functional layer. Bubble point measurements confirmed the membrane pore structure in the microfiltration range (5.0- 6.1 mu m), which provided very high water permeability (900-4000 L h (1) m (2)) at <1.5 bars. A tensile strength of 16 MPa in dry conditions and a wet strength of 0.2 MPa, was considered sufficient for use of these membranes in spiral wound modules. Mirror industry effluent laden with metal ions (Ag+ and Cu2+/Fe3+/Fe2+) when treated with cellulose nanocomposite membranes, showed high ion removal capacity, being 100% for PCNCSL followed by CNCBE than CNCSL. The removal of metal ions was expected to be driven by interactions between negatively charged nanocellulose and the positively charged metal ions.

  • 28.
    Lee, Kian Keat
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Hao, Wenming
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Gustafsson, Mikaela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Morin, Daniel
    Björkman, Eva
    Lilliestråle, Malte
    Björefors, Fredrik
    Andersson, Anna M.
    Hedin, Niklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Tailored activated carbons for supercapacitors derived from hydrothermally carbonized sugars by chemical activation2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 112, s. 110629-110641Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Activated carbons (ACs) are actively researched as electrode materials for supercapacitors and there is a significant interest to produce ACs from sustainable and low cost precursors. In this study, various ACs were prepared from hydrothermally carbonized sugars by KOH activation. Both the hydrothermal carbonization and activation processes were optimized to tailor the properties (e.g. textural properties, chemical composition, N-doping, electrical conductivity) of the ACs. For instance, the Brunauer-Emmett-Teller (BET) surface areas (S-BET) were tuned in the range of 800-3000 m(2) g(-1) with associated variation in the extent of microporosity and pore size distributions (PSDs). The ACs were evaluated electrochemically as materials for supercapacitor electrodes in a symmetrical two-electrode cell using an aqueous electrolyte. The relationship between the electrochemical, textural, electrical, and physicochemical properties were analyzed systematically to understand the key factors determining the electrochemical performance. A high specific capacitance (C-m) of similar to 260 F g(-1) was achieved at a moderately high S-BET of similar to 1300 m(2) g(-1), which was equivalent to a C-m/S-BET of 20 mu F cm(-2), for an optimal AC prepared from hydrothermally carbonized glucose. The very high surface-specific capacitance highlights that the specific surface area is certainly not the sole limiting parameter for effective electrode materials.

  • 29.
    Li, Duan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    de Moraes, Elisangela Guzi
    Colombo, Paolo
    Shen, Zhijian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Preparation of nasal cavity-like SiC-Si3N4 foams with a hierarchical pore architecture2015Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 5, nr 35, s. 27891-27900Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rigid SiC-Si3N4 foams with hierarchical porosity were prepared through protein-based gel-casting followed by radiant sintering in a modified spark plasma sintering (SPS) set-up. The porous bodies sintered at 1500-1700 degrees C for only 10 minutes achieved a compressive strength of 15-21 MPa while keeping a porosity of 60-70 vol%. Gradient porous structures, with pore sizes ranging between 1 to 100 mm, were intersected by the growth of hybrid SiC and Si3N4 nanowires inside the pores resulting in a nasal cavity-like appearance. Gas permeability at room temperature (25 degrees C) and 600 degrees C was evaluated. Darcian permeabilities and non-Darcian permeabilities of all the prepared foams at room temperature fell within (0.354-1.55) x 10(-12) m(2) and (1.60-6.33) x 10(-8) m, respectively. Measurement of the Darcian and non-Darcian permeabilities at 600 degrees C were much higher, at 1.71 x 10(-11) m(2) and 2.68 x 10(-7) m, respectively. The microstructure, stability, gas flow properties and the green synthesis route reveal the potential of these ceramic foams to be used as industrial PM filters for airborne pollutions.

  • 30.
    Liu, Peng
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Luleå University of Technology, Sweden.
    Garrido, Beatriz
    Oksman, Kristiina
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Luleå University of Technology, Sweden.
    Adsorption isotherms and mechanisms of Cu(II) sorption onto TEMPO-mediated oxidized cellulose nanofibers2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 109, s. 107759-107767Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) mediated oxidized cellulose nanofibers (TOCNF) have shown potential in the removal of metal ions from contaminated water owing to their abundant carboxylate groups on their surface, functioning as metal sorption sites. The current work aims to study the kinetics and thermodynamics of the sorption behavior of Cu(II) onto TOCNF, and verify the correlation between Delta[H+] and the corresponding Delta[Cu(II)] in aqueous solution during sorption. Sorption of Cu(II) onto TOCNF was found to be an exothermic process with fast kinetics; reaching equilibrium Cu(II) adsorption in less than 1 min. The sorption data fits well with Langmuir isotherm models. The SEM imaging of the TOCNF after Cu(II) sorption revealed interesting copper-containing nanoparticles, which was further analyzed by using XRD. Besides, a linear correlation between Delta[H+] and the corresponding D [Cu(II)] in the solution was found, which indicates that the Cu(II) sorption capacity might be well predicted and calculated by Delta[H+] or pH variation during Cu(II) ion sorption onto TEMPO oxidized nanocellulose fibers and have potential to develop online sensors for tracking metal ion removal.

  • 31.
    Liu, Peng
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Milletto, Charles
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Monti, Susanna
    Zhu, Chuantao
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Design of ultrathin hybrid membranes with improved retention efficiency of molecular dyes2019Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 9, nr 49, s. 28657-28669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ultrathin layers of 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) Oxidized Cellulose Nanofibers (TOCNF) embedded with Graphene Oxide nanosheets (GOs) in different ratios were built, via the blade coating technique, on a polyvinylidene difluoride (PVDF) substrate to obtain superior membranes for separating water pollutants from aqueous media. Cellulose nanofiber-graphene oxide hybrid materials have shown a great potential for water purification due to their active microporous structure with extended areas rich in negatively charged carboxyl functional groups capable of adsorbing positively charged contaminants efficiently. In contrast to the pristine free-standing TOCNF films, which are completely impermeable, the ultrathin (68 nm thick) hybrid coating with a 100 : 1 TOCNF : GO ratio showed a stable water permeability (816 +/- 3.4 L m(-2) h(-1) bar(-1)) higher than that of common polymeric membranes, and a very efficient size selectivity during filtration of water contaminated by various types of dyes. The membranes had high retention efficiency (82-99%) for dyes with hydrated radii greater than approximate to 0.5 nm due to the favorable combination of electrostatic/hydrophobic interactions with the hybrid matrices and steric entrapment controlled by the pore size. This was confirmed by theoretical calculations that revealed both the structure and dynamic behavior of the dyes in the complex environment of the membranes.

  • 32.
    Mille, Christian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Tyrode, Eric C.
    Corkery, Robert W.
    3d titania photonic crystals replicated from gyroid structures in butterfly wing scales: approaching full band gaps at visible wavelengths2013Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 3, nr 9, s. 3109-3117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    3D titania photonic crystals are replicated from single gyroid structures found in the butterfly Callophrys rubi. Photonic crystals were characterised using SEM imaging, X-ray and Raman scattering and reflection spectroscopy. The overall symmetry and topology of the original single gyroid structures is replicated with high fidelity. Titania replicas display photonic responses that are thermal history dependent. Replicas treated at 700 degrees C, show up to 96% reflectivity at similar to 505 nm, while at lower and higher treatment temperatures the photonic response was not as pronounced. Simulated band structures fitted to the observed spectral reflectivity data constrain the solid volume fractions and dielectric constants of the replicas. The titania photonic crystals were also found to be optically active, with both left- and right-handed single gyroids contributing to the chiral response. The 3D titania photonic crystals replicated here have nearly complete overlapping of partial band gaps, strongly suggesting that materials with full photonic band gaps are experimentally within reach using the general replication approach reported here.

  • 33.
    Mobarak, Hani
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Engström, Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of methyl 3-amino-3,6-dideoxy-alpha-d-galactopyranoside carrying different amide substituents2013Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 3, nr 45, s. 23090-23097Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bacterial polysaccharides may contain rare sugars of different stereochemistry and diverse functional groups; the repertoire can be further extended by varying the exocyclic substituents. Synthesis of four monosaccharides is described utilizing a suitably protected key intermediate obtained by regioselective acetal ring-opening reduction, dexoygenation at C6, alcohol oxidation at C3 followed by formation of an oxime, which was stereoselectively reduced by samarium diiodide to give a 3-amino-derivative having the desired galacto-configuration. Subsequent functionalization was performed resulting in one to four carbon atoms in the amide substituent.

  • 34.
    Nair, Santhosh S.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Chen, Jianhong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Slabon, Adam
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Converting cellulose nanocrystals into photocatalysts by functionalisation with titanium dioxide nanorods and gold nanocrystals2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 61, s. 37374-37381Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose nanocrystals (CNCs) are promising building blocks for water purification due to their high surface area, tuneability of surface charge and grafting of surface groups depending on the pollutants. In this report we have converted CNCs into photocatalysts, without altering the surface groups, byin situgrowth of TiO(2)nanorods (NRs) and functionalization with Au nanocrystals (NCs) for enhanced light absorption. The control of the density of the NRs assures that the CNC surface and functionalities are accessible for the pollutant, followed by the photocatalytic degradation on the light absorption layer under solar illumination. This seed-mediated NR synthesis can be applied to realize a series of CNC-inorganic NR photocatalysts. The low temperature (90 degrees C compared to commonly reported growth at 150 degrees C) of the NR growth provides the opportunity to use nanostructured biopolymers as functional substrates for preparation of photocatalysts using a bio-inspired design.

  • 35. Naseri, Narges
    et al.
    Poirier, Jean-Michel
    Girandon, Lenart
    Fröhlich, Mirjam
    Oksman, Kristiina
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    3-Dimensional porous nanocomposite scaffolds based on cellulose nanofibers for cartilage tissue engineering: tailoring of porosity and mechanical performance2016Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 6, nr 8, s. 5999-6007Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fully bio-based 3-dimensional porous scaffolds based on freeze-dried cellulose nanofibers (70-90 wt%) stabilized using a genipin crosslinked matrix of gelatin and chitosan were prepared. Morphology studies using scanning electron microscopy showed that the scaffolds have interconnected pores with average pore diameters of 75-200 mu m and nanoscaled pore wall roughness, both favorable for cell interactions with cartilage repair. X-ray tomography confirmed the 3-dimensional homogeneity and interconnectivity of the pores as well as the fibrillar structure of the scaffolds. The compression modulus of the scaffolds (1-3 MPa) at room conditions was higher than natural cartilage (approximate to 1 MPa). The lowered compression modulus of 10-60 kPa in phosphate buffered saline (PBS) at 37 degrees C was considered favorable for chondrogenesis. The current study therefore successfully addressed the challenge of tailoring the pore structure and mechanical properties simultaneously for cartilage regeneration. Furthermore, the scaffolds' high porosity (approximate to 95%), high PBS uptake and good cytocompatibility towards chondrocytes are considered beneficial for cell attachment and extracellular matrix (ECM) production.

  • 36.
    Navarro, Julien R. G.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Labelling of N-hydroxysuccinimide-modified rhodamine B on cellulose nanofibrils by the amidation reaction2014Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 4, nr 105, s. 60757-60761Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have labelled cellulose nanofibrils with rhodamine B and characterized the grafting and the fluorescent properties by infrared and UV/visible spectroscopy together with fluorescence spectroscopy and confocal laser scanning microscopy. The cellulose nanofibrils were surface modified with amine groups using 4-(Boc-aminomethyl)phenyl isothiocyanate, that allows grafting of a wide number of commercially available molecules that e.g. contain carboxylic acid groups. The amine-modified cellulose nanofibrils were reacted with N-hydroxysuccinimide-modified rhodamine B ester through the amidation reaction. The labeling of the dye onto CNF results in a red-shift of the absorption and emission bands and despite some quenching of the fluorescence intensity of the surface-bound chromophore, it was possible to image the luminescent CNF at both low and high magnification using a confocal laser scanning microscope.

  • 37.
    Pettersson, Pontus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Barth, Andreas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Correlations between the structure and the vibrational spectrum of the phosphate group. Implications for the analysis of an important functional group in phosphoproteins2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 8, s. 4715-4724Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Density functional theory calculations were used to establish correlations between the structure and the vibrational spectrum of the phosphate group in model compounds for phosphorylated amino acids. The model compounds were acetyl phosphate, methyl phosphate, and p-tolyl phosphate, which represented the phosphorylated amino acids aspartyl phosphate, serine or threonine phosphate, and tyrosine phosphate, respectively. The compounds were placed in different environments consisting of one or several HF or H2O molecules, which modeled interactions of phosphorylated amino acids in the protein environment. The calculations were performed with the B3LYP functional and the 6-311++G(3df, 3pd) basis set. In general, the wavenumbers (or frequencies) of the stretching vibrations of the terminal P-O bonds correlated better with bond lengths of the phosphate group than with its bond angles. The best correlations were obtained with the shortest and the mean terminal P-O bond lengths with standard deviations from the trend line of only 0.2 pm. Other useful correlations were observed with the bond length difference between the shortest and longest terminal P-O bond and with the bond length of the bridging P-O bond.

  • 38.
    Qi, Kezhen
    et al.
    Shenyang Normal University, Shenyang, China.
    Selvaraj, Rengaraj
    Sultan Qaboos University, Muscat, Sultanate of Oman.
    Jeong, Uiseok
    Kwangwoon University, Korea .
    Al-Kindy, Salma M. Z.
    Sultan Qaboos University, Muscat, Sultanate of Oman.
    Sillanpää, Mika
    Lappeenranta University of Technology, FInland.
    Kim, Younghun
    Kwangwoon University, Korea.
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Hierarchical-like multipod γ-MnS microcrystals: solvothermal synthesis, characterization and growth mechanism2015Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 5, nr 13, s. 9618-9620Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Novel hierarchical multipod gamma-MnS microcrystals have been successfully synthesized by a simple solvothermal method, in which manganese acetate was used as a manganese source and thiosemicarbazide was used as both sulfur source and capping agent.

  • 39.
    Qian, Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Xiao, Changhong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zou, Ji
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zhong, Yuan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Shen, Zhijian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Assembled nano-structures from micron-sized precursors2014Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 4, nr 58, s. 30754-30757Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Oriented assembly of small crystals to form larger structures are common in nature and full understanding and control of such process would be beneficial for the forthcoming nano-technologies. Such bottom-up assembly of nano-structures most often requires a precursor of nano-sized crystals. Here we demonstrate a novel laser sintering process that can rupture a submicron-sized zirconia precursor into nano-sized crystals, followed by a rapid oriented assembly of these small crystals. A detailed structure study has been carried out to understand the complex process and a model has been proposed. Such a process sheds light on a new way of fabricating nano-materials using commercialized oxide materials.

  • 40.
    Ribbenstedt, Anton
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Benskin, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Rapid in-plate screening of biotransformation products in single zebrafish embryos2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 45, s. 27812-27819Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A procedure was developed for rapid screening of xenobiotic biotransformation products (bioTPs) in single zebrafish (ZF; Danio rerio) embryos. Exposure was carried out from 0–120 hours post fertilization (hpf) to 6 different concentrations of the model compound propranolol (PPL). Following in-plate extraction and non-target instrumental analysis by high resolution mass spectrometry, suspected bioTPs were identified using custom data filtration scripts and matching to in silico structural predictions. A total of eight PPL bioTPs were identified (five at a level 1 confidence and one at a level 2–3 confidence). These findings supplement previously generated toxicometabolomic models derived from the same dataset, and were obtained without conducting additional exposure experiments. In addition to facilitating assessments of inter-individual variability in bioTP production in ZF embryos, we demonstrate that bioTPs can be elucidated using extremely small quantities of biomass (i.e. ∼200 μg). To the best of our knowledge, this is the first time bioTP elucidation has been carried out in single ZF embryos.

  • 41.
    Saeidi, Kamran
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Kvetkova, Lenka
    Lofajc, Frantisek
    Shen, Zhijian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Austenitic stainless steel strengthened by the in situ formation of oxide nanoinclusions2015Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 5, nr 27, s. 20747-20750Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An austenitic stainless steel was prepared by laser melting. High resolution transmission electron microscopy with energy dispersive spectrometry confirmed the in situ formation of oxide nanoinclusions with average size less than 50 nm. Scanning electron microscopy examination revealed the homogeneous dispersion of the oxide nanoinclusions in the steel matrix. The tensile and yield strengths of the prepared specimens were 703 and 456 MPa respectively with high ductility which is significantly improved compared to its conventionally casted counterpart.

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  • 42.
    Santoro, Stefano
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Azeredo, Juliano B.
    Nascimento, Vanessa
    Sancineto, Luca
    Braga, Antonio L.
    Santi, Claudio
    The green side of the moon: ecofriendly aspects of organoselenium chemistry2014Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 4, nr 60, s. 31521-31535Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Organoselenium chemistry has proven to be a powerful tool for organic synthesis over several decades. Nevertheless, the use of selenating reagents has often been limited by a generally bad reputation surrounding selenium toxicity and its potential impact on the environment. In this review we would like to stress some aspects that will encourage the reader to discover an unexpected green side to this element and the chemistry connected with its organic derivatives.

  • 43. Seisenbaeva, Gulaim A.
    et al.
    Melnyk, Inna V.
    Hedin, Niklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Chen, Yang
    Eriksson, Philip
    Trzop, Elzbieta
    Zub, Yuriy L.
    Kessler, Vadim G.
    Molecular insight into the mode-of-action of phosphonate monolayers as active functions of hybrid metal oxide adsorbents. Case study in sequestration of rare earth elements2015Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 5, nr 31, s. 24575-24585Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The insight into the molecular aspects of ligand grafting and potential maximal capacity of hybrid organic-inorganic adsorbents bearing phosphonate ligand monolayers as active functions was obtained by single crystal X-ray studies of ligand-functionalized titanium alkoxide complexes. The attachment of molecules occurs generally in the tripodal vertical fashion with the minimal distance between them being about 8.7 angstrom, resulting in 0.19 nm(2) as the minimal surface area per function. In the present experimental work the theoretical loading capacity could almost be achieved for functionalization of mesoporous nanorods of anatase with imino-bis-methylphosphonic acid (IMPA, NH(CH2PO3H2)(2)) or aminoethylphosphonic acid (AEPA, H2NC2H4PO3H2). The products had the same morphology as the starting material, as was established by SEM and optical microscopy. The size and structure of the individual nanoparticles of the constituting inorganic component of the material were preserved and practically unchanged through the surface modification, as established by powder XRD and EXAFS studies. The surface area of the inorganic-organic hybrids decreased somewhat from the initial similar to 250 m(2) g(-1), on adsorption of AEPA (0.21 mmol g(-1)) to similar to 240 m(2) g(-1), and on adsorption of IMPA (0.17 mmol g(-1)) to similar to 190 m(2) g(-1). The ligands were bound effectively to the surface according to TGA, EDS and FTIR analyses and remained in the mono-deprotonated form. The produced hybrid adsorbents had for the selected pH (3.5) high capacities towards adsorption of Rare Earth Element (REE) cations, but with equilibria achieved relatively slowly. The composition of the surface complexes was determined as M : L = 1 : 1 for IMPA, but varied for the AEPA from 1 : 3 to 1 : 1 dependent on the REE, which can be interpreted in terms of charge compensation as the major driving force behind binding. The cation desorption in strongly acidic media for recuperation of the adsorbed REE and the relative capacity of the re-used adsorbent have been quantified.

  • 44. Selvaraj, Rengaraj
    et al.
    Qi, Kezhen
    Al-Kindy, Salma M. Z.
    Sillanpaa, Mika
    Kim, Younghun
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    A simple hydrothermal route for the preparation of HgS nanoparticles and their photocatalytic activities2014Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 4, nr 30, s. 15371-15376Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    HgS nanoparticles have been successfully prepared by a hydrothermal method using polyethylene glycol (PEG) as stabilizing agent and characterized by a variety of methods. Our experiments confirmed that the size of the HgS nanocrystals could be easily modified by tuning the chain length of PEG. X-ray powder diffraction (XRD) results for the nanoparticles revealed the hexagonal structure of the HgS, i. e. a-phase known as cinnabar. Morphological studies performed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the synthesized nanocrystals were nanoparticles. Furthermore, a rational mechanism of the formation and evolution of the products was proposed. The optical properties of HgS were investigated by diffuse reflectance spectroscopy (DRS), which indicated that the band gap of the nanoparticles is slightly decreased from 2.05 to 2.00 eV as the average particle size decreases from 55 to 35 nm. Furthermore, the photocatalytic activity studies of the particles demonstrated their excellent photocatalytic performance in rapidly degrading aqueous methylene blue dye solution under visible light irradiation. These results suggest that HgS nanoparticles will be an interesting candidate of photocatalyst working in visible light range.

  • 45.
    Siegbahn, Per E. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A quantum chemical approach for the mechanisms of redox-active metalloenzymes2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 6, s. 3495-3508Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    During the past 20 years, quantum chemistry has grown to be a significant part in the investigation of mechanisms for redox-active enzymes. In our group we have developed an approach that has been applied to a large number of such systems. Hybrid density functional theory (hybrid DFT) has from the start of these investigations been the leading electronic structure tool. An understanding of how the method works in practice has significantly improved the accuracy and applicability. During the past ten years, it has been found that the results for redox enzymes mainly depend on the chosen fraction of exact exchange in the functional, and that a choice of 15% has worked best. The idea has therefore been to vary that fraction over a reasonable range and study the relative energy dependence. For modeling the enzymes, a cluster approach has been developed. In the present review the development of the method we used is described from its start in work on photosystem II, fifteen years ago. Examples from a few recent applications are described, where the metals have been iron, nickel, copper, cobalt or manganese. The results are in excellent agreement with available experiments, and a large number of new predictions have been made.

  • 46.
    Stingaciu, Marian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zhu, Bin
    Singh, Manish
    Johnsson, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Single-component fuel cells fabricated by spark plasma sintering2012Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 2, nr 32, s. 12140-12143Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Porous single-component fuel cells, made up of a single layer of mixed ionic and electronic conductivity, have been fabricated using spark plasma sintering (SPS) and their performances were tested in methanol. It was possible to optimize the current/power output by changing the sintering conditions which directly influence the grain size, porosity, grain contacts and conducting paths for the fabricated cells.

  • 47. Sun, Jun
    et al.
    Jennepalli, Sreenu
    Lee, Matthew
    O'Carroll, Denis M.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Manefield, Michael J.
    Das, Biswanath
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. The University of New South Wales, Australia.
    Kumar, Naresh
    Removal of per- and polyfluoroalkyl substances (PFAS) from water by ceric(iv) ammonium nitrate2021Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 11, nr 29, s. 17642-17645Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ceric(IV) ammonium nitrate (CAN) in aqueous medium acts as an excellent precipitating agent for perfluorooctanesulfonic acid (PFOS). The Ce(IV) center plays a crucial role. Interestingly, Ce(III) chloride showed much less effectiveness under similar conditions. The efficacy of CAN was reduced upon changing the substrate to perfluorooctanoic acid (PFOA).

  • 48. Svensson, Fredric G. G.
    et al.
    Daniel, Geoffrey
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Seisenbaeva, Gulaim A. A.
    Kessler, Vadim G. G.
    Titanium phosphonate oxo-alkoxide clusters: solution stability and facile hydrolytic transformation into nano titania2020Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 10, nr 12, s. 6873-6883Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Titanium (oxo-) alkoxide phosphonate complexes were synthesized using different titanium precursors and tert-butylphosphonic acid (tBPA) as molecular models for interaction between phosphonates and titania surfaces and to investigate the solution stability of these species. Reflux of titanium(iv) ethoxide or titanium(iv)(diisopropoxide)bis(2,4-pentadionate) with tert-butylphosphonic acid in toluene-ethanol mixture or acetone yielded seven titanium alkoxide phosphonate complexes; [Ti-5(mu(3)-O)(mu(2)-O)(mu-HOEt)(2)(mu-OEt)(3)(mu(2)-OEt)(mu(3)-tBPA)(3)(mu(3)-HtBPA)(mu(2)-tBPA)(2)(mu(2)-HtBPA)]center dot 3EtOH, 1, [Ti4O(mu-OEt)(5)(mu(2)-OEt)(7)(mu(3)-tBPA)], 2, [Ti-4(mu(2)-O)(2)(mu-OEt)(2)(mu-HOEt)(2)(mu(2)-tPBA)(2)(mu(2)-HtPBA)(6)]center dot 4EtOH, 3, [Ti-4(mu(2)-O)(2)(mu-OEt)(2)(mu-HOEt)(2)(mu(2)-tPBA)(2)(mu(2)-HtPBA)(6)]center dot 2EtOH, 4, [Ti-6(mu(2)-O)(mu(3)-O)(2)(mu(2)-OEt)(5)(mu-OEt)(6)(mu(3)-tBPA)(3)(mu(3)-HtBPA)], 5, [Ti-4(mu-(OPr)-O-i)(4)(acac)(4)(mu(2)-tBPA)(4)], 6 and [Ti-5(mu(4)-O)(mu(2)-O)(3)(mu(2)-OEt)(4)(mu-OEt)(6)(mu-HOEt)(mu(3)-tBPA)](2), 7. The binding mode of tBPA to the titanium oxo-core were either double or triple bridging or a combination of the two. No monodentate or chelating coordination was observed. P-31 NMR spectrometry of dissolved single crystals indicates that 1 and 5 retain their solid-state structures in solution, the latter even on moderate heating, while 6 and 7 dissolved into several other forms. The complexes were found to be sensitive towards hydrolysis, proceeding in a topotactic fashion with densification of the material into plates and lamellae resulting finally in core-shell nanoparticles with a crystalline core (anatase) and an amorphous outer shell upon contact with water at room temperature as observed by HRTEM and AFM analyses. P-31 NMR data supported degradation after addition of water to solutions of the complexes. Hydrolysis under different conditions affords complex oxide structures of different morphologies.

  • 49. Tessitore, Gabriella
    et al.
    Mudring, Anja-Verena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Krämer, Karl W.
    Upconversion luminescence in sub-10 nm b-NaGdF4: Yb3+,Er3+ nanoparticles2019Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 9, nr 60, s. 34784-34792Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sub-10 nm beta-NaGdF4:18% Yb3+,2% Er3+ nanoparticles were synthesized in ethylene glycol and various ionic liquids under microwave heating. The products were characterized by powder X-ray diffraction, electron microscopy, and upconversion (UC) luminescence spectroscopy. After Yb3+ excitation at 970 nm, Er3+ ions are excited by energy transfer upconversion and show the typical green and red emission bands. The UC luminescence intensity was optimized with respect to reactant concentrations, solvents, and reaction temperature and time. The strongest UC emission was achieved for sub-20 nm core-shell nanoparticles which were obtained in the ionic liquid diallyldimethylammonium bis(trifluoromethanesulfonyl)amide from a two-step synthesis without intermediate separation. Strictly anhydrous reaction conditions, a high fluoride/rare earth ion ratio, and a core-shell structure are important parameters to obtain highly luminescent nanoparticles. These conditions reduce non-radiative losses due to defects and high energy acceptor modes of surface ligands. A low power excitation of the core-shell particles by 70 mW at 970 nm results in an impressive UC emission intensity of 0.12% compared to the bulk sample.

  • 50.
    Turdean-Ionescu, Claudia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Stevensson, Baltzar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Grins, Jekabs
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Izquierdo-Barba, Isabel
    Garcia, Ana
    Arcos, Daniel
    Vallet-Regi, Maria
    Edén, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Composition-dependent in vitro apatite formation at mesoporous bioactive glass-surfaces quantified by solid-state NMR and powder XRD2015Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 5, nr 105, s. 86061-86071Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silicate-based bioactive glasses exhibit bone-bonding properties due to the formation of a hydroxycarbonate apatite (HCA) layer at the glass surface on its contact with living tissues. This bone-healing process is triggered by ionic exchange between the glass and the surrounding fluids and thereby depends on the glass composition. In this work, the HCA formation from three mesoporous bioactive glasses (MBGs) of different compositions immersed in a simulated body fluid (SBF) was monitored for variable time intervals between 15 minutes to 30 days. By utilizing two independent assessment techniques, solid-state P-31 NMR spectroscopy and powder X-ray diffraction (PXRD), we report the first quantitative assessment of the HCA growth (i.e., in vitro bioactivity) from a bioactive glass: both techniques allow for monitoring the crystallization of the amorphous calcium phosphate (ACP) precursor into HCA, i.e., a profile of the relative ACP/HCA fractions of the biomimetic phosphate layer formed at each MBG surface and SBF-exposure period. The amount of HCA present in each solid specimen after the SBF treatment, as well as the composition of the remaining cation-depleted MBG phase, was determined from PXRD data in conjunction with measured concentrations of Ca, Si, and P in the solution. In contrast with previous findings from in vitro bioactivity assessments of the same MBG compositions, the HCA formation is herein observed to increase concurrently with the Ca and P contents of the MBG; these apparently different composition-bioactivity observations stem from a significantly lower MBG-loading in the SBF solution utilized herein. The results are discussed in relation to the general task of performing bioactivity testing in SBF, where we highlight the importance of adapting the concentration of the biomaterial to its composition to avoid perturbing the HCA crystallization and thereby altering the outcome of the test.

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