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  • 1.
    Akhtar, Farid
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    Keshavarzi, Neda
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Shakarova, Dilshod
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cheung, Ocean
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Aluminophosphate monoliths with high CO2-over-N2 selectivity and CO2 capture capacity2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 99, p. 55877-55883Article in journal (Refereed)
    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.

  • 2. Alanis, Andrés
    et al.
    Hernández Valdés, Josué
    Maria Guadalupe, Neira-Velázquez
    Lopez, Ricardo
    Mendoza, Ricardo
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Diaz de León, Ramón
    Valencia, Luis
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Plasma surface-modification of cellulose nanocrystals: a green alternative towards mechanical reinforcement of ABS2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 30, p. 17417-17424Article in journal (Refereed)
    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.

  • 3. Bassyouni, Fatma A.
    et al.
    Abu-Baker, Sherifa M.
    Mahmoud, Khaled
    Moharam, Maysa
    El-Nakkady, Sally S.
    Rehim, Mohamed Abdel
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Synthesis and biological evaluation of some new triazolo[1,5-a]quinoline derivatives as anticancer and antimicrobial agents2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 46, p. 24131-24141Article in journal (Refereed)
    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.

  • 4.
    Bermejo Gómez, Antonio
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Holmberg, Pär
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martin-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition metal-catalyzed redox isomerization of codeine and morphine in water2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 74, p. 39519-39522Article in journal (Refereed)
    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.

  • 5.
    Cheung, Ocean
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zeolites and related sorbents with narrow pores for CO2 separation from flue gas2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 28, p. 14480-14494Article, review/survey (Refereed)
    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.

  • 6. Cheung, Ocean
    et al.
    Zhang, Peng
    Frykstrand, Sara
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sommariva, Marco
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Strømme, Maria
    Nanostructure and pore size control of template-free synthesised mesoporous magnesium carbonate2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 78, p. 74241-74249Article in journal (Refereed)
    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.

  • 7. El-Seedi, Hesham R.
    et al.
    El-Shabasy, Rehan M.
    Khalifa, Shaden A. M.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. 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 applications2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 42, p. 24539-24559Article, review/survey (Refereed)
    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.

  • 8. Francois, Camille
    et al.
    Pourchet, Sylvie
    Boni, Gilles
    Fontaine, Stephane
    Gaillard, Yves
    Placet, Vincent
    Galkin, Maxim V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Orebom, Alexander
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Plasseraud, Laurent
    Diglycidylether of iso-eugenol: a suitable lignin-derived synthon for epoxy thermoset applications2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 73, p. 68732-68738Article in journal (Refereed)
    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.

  • 9. 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.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Biendicho, Jordi Jacas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Tuning the high-temperature properties of Pr2NiO4+delta by simultaneous Pr- and Ni-cation replacement2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 40, p. 33951-33958Article in journal (Refereed)
    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).

  • 10. Jesús Naveja, J.
    et al.
    Norinder, Ulf
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences. Swetox, Karolinska Institutet, Sweden.
    Mucs, Daniel
    López-López, Edgar
    Medina-Franco, Jose L.
    Chemical space, diversity and activity landscape analysis of estrogen receptor binders2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 67, p. 38229-38237Article in journal (Refereed)
    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.

  • 11. Karim, Zoheb
    et al.
    Hakalahti, Minna
    Tammelin, Tekla
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    In situ TEMPO surface functionalization of nanocellulose membranes for enhanced adsorption of metal ions from aqueous medium2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 9, p. 5232-5241Article in journal (Refereed)
    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.

  • 12. Karim, Zoheb
    et al.
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (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 effluents2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 25, p. 20644-20653Article in journal (Refereed)
    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.

  • 13.
    Lee, Kian Keat
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hao, Wenming
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gustafsson, Mikaela
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Morin, Daniel
    Björkman, Eva
    Lilliestråle, Malte
    Björefors, Fredrik
    Andersson, Anna M.
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Tailored activated carbons for supercapacitors derived from hydrothermally carbonized sugars by chemical activation2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 112, p. 110629-110641Article in journal (Refereed)
    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.

  • 14.
    Li, Duan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    de Moraes, Elisangela Guzi
    Colombo, Paolo
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Preparation of nasal cavity-like SiC-Si3N4 foams with a hierarchical pore architecture2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 35, p. 27891-27900Article in journal (Refereed)
    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.

  • 15.
    Liu, Peng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    Garrido, Beatriz
    Oksman, Kristiina
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    Adsorption isotherms and mechanisms of Cu(II) sorption onto TEMPO-mediated oxidized cellulose nanofibers2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 109, p. 107759-107767Article in journal (Refereed)
    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.

  • 16.
    Liu, Peng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Milletto, Charles
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Monti, Susanna
    Zhu, Chuantao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Design of ultrathin hybrid membranes with improved retention efficiency of molecular dyes2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 49, p. 28657-28669Article in journal (Refereed)
    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.

  • 17.
    Mille, Christian
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Tyrode, Eric C.
    Corkery, Robert W.
    3d titania photonic crystals replicated from gyroid structures in butterfly wing scales: approaching full band gaps at visible wavelengths2013In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, no 9, p. 3109-3117Article in journal (Refereed)
    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.

  • 18.
    Mobarak, Hani
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Engström, Olof
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of methyl 3-amino-3,6-dideoxy-alpha-d-galactopyranoside carrying different amide substituents2013In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, no 45, p. 23090-23097Article in journal (Refereed)
    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.

  • 19. Naseri, Narges
    et al.
    Poirier, Jean-Michel
    Girandon, Lenart
    Fröhlich, Mirjam
    Oksman, Kristiina
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    3-Dimensional porous nanocomposite scaffolds based on cellulose nanofibers for cartilage tissue engineering: tailoring of porosity and mechanical performance2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 8, p. 5999-6007Article in journal (Refereed)
    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.

  • 20.
    Navarro, Julien R. G.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Labelling of N-hydroxysuccinimide-modified rhodamine B on cellulose nanofibrils by the amidation reaction2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 105, p. 60757-60761Article in journal (Refereed)
    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.

  • 21.
    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
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hierarchical-like multipod γ-MnS microcrystals: solvothermal synthesis, characterization and growth mechanism2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 13, p. 9618-9620Article in journal (Refereed)
    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.

  • 22.
    Qian, Bin
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Xiao, Changhong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Ji
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhong, Yuan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Assembled nano-structures from micron-sized precursors2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 58, p. 30754-30757Article in journal (Refereed)
    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.

  • 23.
    Saeidi, Kamran
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kvetkova, Lenka
    Lofajc, Frantisek
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Austenitic stainless steel strengthened by the in situ formation of oxide nanoinclusions2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 27, p. 20747-20750Article in journal (Refereed)
    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.

  • 24.
    Santoro, Stefano
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Azeredo, Juliano B.
    Nascimento, Vanessa
    Sancineto, Luca
    Braga, Antonio L.
    Santi, Claudio
    The green side of the moon: ecofriendly aspects of organoselenium chemistry2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 60, p. 31521-31535Article in journal (Refereed)
    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.

  • 25. Seisenbaeva, Gulaim A.
    et al.
    Melnyk, Inna V.
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (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 elements2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 31, p. 24575-24585Article in journal (Refereed)
    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.

  • 26. Selvaraj, Rengaraj
    et al.
    Qi, Kezhen
    Al-Kindy, Salma M. Z.
    Sillanpaa, Mika
    Kim, Younghun
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A simple hydrothermal route for the preparation of HgS nanoparticles and their photocatalytic activities2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 30, p. 15371-15376Article in journal (Refereed)
    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.

  • 27.
    Turdean-Ionescu, Claudia
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Izquierdo-Barba, Isabel
    Garcia, Ana
    Arcos, Daniel
    Vallet-Regi, Maria
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Composition-dependent in vitro apatite formation at mesoporous bioactive glass-surfaces quantified by solid-state NMR and powder XRD2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 105, p. 86061-86071Article in journal (Refereed)
    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.

  • 28. Wang, Jing
    et al.
    Guo, Peng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Dou, Maofeng
    Cheng, Yajuan
    Jonsson, Pär G.
    Zhao, Zhe
    Visible light-driven g-C3N4/m-Ag2Mo2O7 composite photocatalysts: synthesis, enhanced activity and photocatalytic mechanism2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 92, p. 51008-51015Article in journal (Refereed)
    Abstract [en]

    The g-C3N4/m-Ag2Mo2O7 composite photocatalysts with well-aligned band structures are successfully fabricated by a simple two-step method with different mass contents of m-Ag2Mo2O7. The as-prepared samples are evaluated as photocatalysts toward rhodamine B (RhB) degradation in aqueous solution under visible light irradiation (lambda > 420 nm). The results demonstrate that the photocatalytic activities of the composites are strongly influenced by the weight ratio of g-C3N4 to m-Ag2Mo2O7. When it is 6 : 1, the composite exhibits the highest photocatalytic efficiency. More specifically, this value is as high as 3.4 and 6.1 times that of pure g-C3N4 and P25 respectively. In order to investigate the mechanism causing the enhanced photocatalytic degradation, the band structures are determined by UV-vis diffuse reflection spectroscopy and the Mott-Schottky technique. Moreover, the reactive radicals involved in the photocatalytic process are examined in detail via active species trapping (AST) experiments. The improved photocatalytic activities can be attributed to the efficient separation of the photo-induced charge carriers and the strong redox capacities benefit from the synergetic effect between g-C3N4 and m-Ag2Mo2O7.

  • 29. Wang, Liping
    et al.
    Schütz, Christina
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Royal Institute of Technology, Sweden.
    Salazar-Alvarez, German
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Royal Institute of Technology, Sweden.
    Titirici, Maria-Magdalena
    Carbon aerogels from bacterial nanocellulose as anodes for lithium ion batteries2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 34, p. 17549-17554Article in journal (Refereed)
    Abstract [en]

    Carbon aerogels with large open pores and high surface area are fabricated via pyrolysis of a readily available natural resource, e. g., bacterial nanocellulose (BNC) aerogels. Freeze-drying of the BNC hydrogels is used to preserve the 3D open network structure upon calcination whereas using Fe(III) improves the yield and H/C ratio. These carbon aerogels are explored as anodes in lithium ion batteries where it is shown that they deliver superior capacity retention and rate performance compared to other carbon-based materials.

  • 30. Yang, X.
    et al.
    Li, Duan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ren, Z. H.
    Zeng, R. G.
    Gong, S. Y.
    Zhou, D. K.
    Tian, H.
    Li, J. X.
    Xu, G.
    Shen, Zhijian James
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Han, G. R.
    Colossal dielectric performance of pure barium titanate ceramics consolidated by spark plasma sintering2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 79, p. 75422-75429Article in journal (Refereed)
    Abstract [en]

    A facile sol-gel-hydrothermal method was developed to prepare well-dispersed BaTiO3 (BT) nanocrystals with a size of about 20 nm. By using such nanopowder, dense BT nanoceramics were densified via spark plasma sintering (SPS). Dielectric measurements reveal that pure BT nanoceramics have an extremely high permittivity up to 6 x 10(4) and a low dielectric loss. On the basis of microstructure characterization and dielectric measurement, it was proposed that the polaron dipoles configured by oxygen vacancies and Ti3+ cations within the grains could contribute to the colossal dielectric permittivity of the ceramics. By using the thermally activated polaron hopping model, a large activation energy EA has been determined (0.135 eV) below the Curie temperature, possibly due to the coupling of polaron dipoles and intrinsic ferroelectric dipoles. This simple method offers the possibility to produce pure BT nanoceramics with a colossal permittivity.

  • 31.
    Yang, Yi
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Changzhou Vocational Institute of Engineering, China.
    Shen, Kang
    Lin, Jun-Zhong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhou, Yong
    Liu, Qiao-yun
    Hang, Cheng
    Abdelhamid, Hani Nasser
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhang, Zhen-qin
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). KTH Royal Institute of Technology, Sweden.
    A Zn-MOF constructed from electron-rich pi-conjugated ligands with an interpenetrated graphene-like net as an efficient nitroaromatic sensor2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 51, p. 45475-45481Article in journal (Refereed)
    Abstract [en]

    A novel zinc-based luminescent metal-organic framework (Zn-MOF) has been successfully constructed based on a designed flexible and electron-rich N-involved linker (HL = 4-(bis(4-(pyridin-4-yl) phenyl) amino) benzoic acid). The framework of this Zn-MOF exhibits a 2-fold interpenetrated network which is composed of (3,3)-c sheets. The Zn-MOF has a strong solid state emission at 512 nm. The luminescence signal of the Zn-MOF can be quenched efficiently by trace amounts of electron-deficient nitroaromatics, especially 2,4,6-trinitrophenol (TNP). The quenching constant (K-sv) for TNP is 2.11 x 10(4) M-1, indicating that this framework can be employed as an excellent chemical sensor for identifying and quantifying TNP. This work highlights a strategy for designing a N-involved p-electron-rich enhanced ligand with nucleophilic properties for MOF-based materials as sensors. It also paves the way toward exploring other more efficient MOF materials as sensors for determining electron-deficient nitroaromatics.

  • 32.
    Yu, Yang
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Structure-composition relationships of bioactive borophosphosilicate glasses probed by multinuclear B-11, Si-29, and P-31 solid state NMR2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 103, p. 101288-101303Article in journal (Refereed)
    Abstract [en]

    By combining B-11, Si-29, and P-31 nuclear magnetic resonance (NMR) experimental results, we present a comprehensive structural investigation of 15 borophosphosilicate (BPS) glasses of the Na2O-CaOB2O3- SiO2-P2O5 system: in two base compositions comprising 46 mol% (S46) and 49 mol% (S49) SiO2, progressive replacements of SiO2 by B2O3 were performed at a constant total Na2O and CaO content. The S46 glass members constitute B-bearing analogs of 45S5 Bioglass that is utilized extensively for bone grafting in periodontal and orthopedic surgery. Orthophosphate ions prevail throughout all structures, while the silicate network polymerization increases slightly with a growing amount of B2O3 in the glass. B-11 NMR revealed continuous BO3 -> BO4 conversions for increasing B2O3 content, with asymptotic fractions of 34% and 43% of B-[4] coordinations out of the borate speciation observed for the series of S46 and S49 glasses, respectively. While all BPS glasses are homogeneous across a mm-scale, strong preferences for B-[3]-O-B-[3] and B-[4]-O-Si-[4] bond formation lead to structures comprising (sub) nm-sized domains of BO3 groups in boroxol rings and borosilicate networks built by SiO4 and BO4 tetrahedra. These borate/ borosilicate networks are merged mainly by B-[4](3Si) and B-[3](1Si) moieties in Si-rich BPS glasses (where each value in parentheses specifies the number of bonds to Si atoms), while B-[4](3Si) and B-[4](2Si) groups are the dominant network contact points in the B-rich glasses. We discuss the partitioning of non-bridging oxygen ions between the BO3 and SiO4 groups, the relative propensities for B-[4]-O-Si-[4] and B-[4]-O-B-[3] bond formation, as well as the expected bearings of our proposed BPS structural model for the glass degradation in aqueous media, where we identify the fractional population of B-[4] coordinations and the silicate network connectivity to constitute the dissolution-controlling parameters.

1 - 32 of 32
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