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  • 1.
    Adolfsson, Karin H.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hassanzadeh, Salman
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Valorization of cellulose and waste paper to graphene oxide quantum dots2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 34, s. 26550-26558Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biobased graphene oxide quantum dots (GOQD) were derived from cellulose via carbon nanospheres (CN) as intermediate products. Solid CN were synthesized from cellulose through microwave-assisted hydrothermal degradation of alpha-cellulose with H2SO4 as a catalyst at 160 degrees C. The obtained CN were further utilized for the synthesis of GOQD by a two-step reaction including 30 minutes of sonication followed by heating at 90 degrees C under O-rich acidic conditions (HNO3). This process broke down the 3D CN to 2D GOQD. The size of the synthesized GOQD was controlled by the heating time, reaching a dot diameter of 3.3 nm and 1.2 nm after 30 and 60 minutes of heating, respectively. The synthesis process and products were characterized by multiple analytical techniques including FTIR, TGA, SEM, TEM, XPS, XRD, BET, DLS and AFM. Interesting optical properties in aqueous solutions were demonstrated by UV/Vis and fluorescence spectroscopy. Finally we demonstrated that corresponding GOQD can be synthesized from waste paper. This production route thus uses renewable and cheap starting materials and relatively mild synthesis procedures leads to instant nanometric production of 2D dots. In addition it enables recycling of low quality waste to value-added products.

  • 2.
    Akan, Rabia
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Parfeniukas, Karolis
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Carmen
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Toprak, M. S.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Ulrich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructures2018Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, nr 23, s. 12628-12634Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based X-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HFH2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of ≈0.7 μm min-1, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures. 

  • 3.
    Andersson, Richard
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Cabedo, L.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Olsson, Richard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Ström, Valter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Superparamagnetic [sic] nanofibers by electrospinning2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 26, s. 21413-21422Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The preparation of superparamagnetic thin fibers by electrospinning dispersions of nanosized magnetite (Fe3O4, SPIO/USPIO) in a PMMA/PEO polymer solution is reported. The saturation magnetization and coercivity were not affected by the concentration (0, 1, 10, 20 wt%) or fiber orientation, showing hysteresis loops with high magnetization (64 A m(2) kg(-1) @ 500 kA m(-1)) and record low coercivity (20 A m(-1)). AC susceptibility measurements vs. temperature at frequencies from 60 to 2 kHz confirmed superparamagnetism. The mechanical properties were only slightly dependent on the particle concentration because the nanoparticles were separately encapsulated by the polymer. A uniform fibre fracture cross section was found at all the investigated particle contents, which suggests a strong interaction at the polymer/particle interface. A theoretical value of the magnetic low field susceptibility was calculated from the Langevin function and compared with measured values. The results show a distinct but concentration-independent anisotropy, favoring magnetization along the fiber orientation with no sign of exchange interaction, explained by complete nanoparticle separation. Superparamagnetism cannot be inferred from particle size alone, so a relevant interpretation and criterion for superparamagnetism is presented, in accordance with Neel's original definition. From the measurements, it can be concluded that magnetic characterization can be used to elucidate the material morphology beyond the resolution of available microscopy techniques (TEM and SEM).

  • 4. Banerjee, Chandrima
    et al.
    Pal, Semanti
    Ahlberg, Martina
    Nguyen, T. N. Anh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik. Vietnam Acad Sci & Technol, Vietnam.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik. Univ Gothenburg, Sweden.
    Barman, Anjan
    All-optical study of tunable ultrafast spin dynamics in [Co/Pd]/NiFe systems: the role of spin-twist structure on Gilbert damping2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 83, s. 80168-80173Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate optically induced ultrafast magnetization dynamics in [Co(0.5 nm)/Pd(1 nm)](5)/NiFe(t) exchange-spring samples with tilted perpendicular magnetic anisotropy using a time-resolved magneto-optical Kerr effect magnetometer. The competition between the out-of-plane anisotropy of the hard layer, the in-plane anisotropy of the soft layer and the applied bias field reorganizes the spins in the soft layer, which are modified further with the variation in t. The spin-wave spectrum, the ultrafast demagnetization time, and the extracted damping coefficients - all depend on the spin distribution in the soft layer, while the latter two also depend on the spin-orbit coupling between the Co and Pd layers. The spin-wave spectra change from multimode to single-mode as t decreases. At the maximum field reached in this study, H = 2.5 kOe, the damping shows a nonmonotonic dependence on t with a minimum at t = 7.5 nm. For t < 7.5 nm, intrinsic effects dominate, whereas for t > 7.5 nm, extrinsic effects govern the damping mechanisms.

  • 5.
    Banerjee, Indradumna
    et al.
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi.
    Salih, Tagrid
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi.
    Ramachandraiah, Harisha
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Erlandsson, Johan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Tidigare Institutioner (före 2005), Kemi.
    Araújo, A. C.
    Karlsson, M.
    Russom, Aman
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Slipdisc: A versatile sample preparation platform for point of care diagnostics2017Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 56, s. 35048-35054Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report a microfluidic sample preparation platform called "Slipdisc" based on slipchip technology. Slipdisc is a rotational slipchip that uses a unique hand-wound clockwork mechanism for precise movement of specially fabricated polycarbonate discs. In operation, the microchannels and microchambers carved on the closely aligned microfluidic discs convert from continuous filled paths to defined compartments using the slip movement. The clockwork mechanism introduced here is characterised by a food dye experiment and a conventional HRP TMB reaction before measuring lactate dehydrogenase (LDH) enzyme levels, which is a crucial biomarker for neonatal diagnostics. The colorimetry based detection of LDH was performed with an unmodified camera and an image analysis procedure based on normalising images and observing changes in red channel intensity. The analysis showed a close to unity coefficient of determination (R2 = 0.96) in detecting the LDH concentration when compared with a standard Chemical Analyser, demonstrating the excellent performance of the slipdisc platform with colorimetric detection. The versatile point of care sample preparation platform should ideally be suited for a multitude of applications at resource-limited settings.

  • 6.
    Bondarchuk, Sergey V.
    et al.
    Bogdan Khmelnitsky Cherkasy National University, Ukraine.
    Minaev, Boris F.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Bogdan Khmelnitsky Cherkasy National University, Ukraine.
    Thermally accessible triplet state of pi-nucleophiles does exist. Evidence from first principles study of ethylene interaction with copper species2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 15, s. 11558-11569Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three different models of ethylene interaction with copper species, namely, the Cu(100) surface, odd-numbered copper clusters C2H4/Cu-n (where n = 3, 7, 11, 15, 17, 19, 21, 25 and 27) and atomic copper C2H4/Cu were studied theoretically. It was found that the ethylene molecule possesses three different types of bonding depending on the presence of the unpaired spin on the reacting copper atom. These bonding structures demonstrate different types of band gap (bulk) or SOMO-LUMO gaps (cluster/atom), where SOMO stands for the singly occupied and LUMO means the lowest unoccupied molecular orbitals of the copper species. The obtained results are in good agreement with the previous experimental and computational results on the structural, spectral and energetic properties of the studied species. The bulk copper and sub-nanosized clusters (n > 7) build up the mono-pi-bonded ground state complexes with ethylene where the latter species possesses the C-2v symmetry. The single-atom complex C2H4/Cu forms the CS-symmetrical ground state (X) over tilde (2)A' and the excited B-2(2) and B-4 state complexes of the C-2v and C-2 symmetry, respectively. The (X) over tilde (2)A' state complex is mono-sigma-bonded and involves the singlet ethylene moiety. The more tightly bound excited B-2(2) complex has the di-sigma-bonded structure and corresponds to the triplet ethylene. The adiabatic energy difference between the B-2(2) and (X) over tilde (2)A' states is equal to 10.8 kcal mol(-1) and can be ascribed to the singlet-triplet splitting of the ethylene moiety interacting with copper. The QTAIM analysis supports the coordination type of the Cu-C bonds in all the studied complexes. Formation of the C2H4/Cu(100), C2H4/Cu-n and C2H4/Cu species is in accord with the well-known Dewar-Chatt-Duncanson model, in such a way that the opposing sigma-donation step yields the ground state complex ((X) over tilde (2)A'), while the subsequent more expensive supporting pi*-back donation step provides the excited B-2(2) state complex. In the present paper we have developed a computational procedure to optimize the latter complex.

  • 7.
    Bruce, Carl
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Javakhishvili, Irakli
    Fogelström, Linda
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Hvilsted, Søren
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Well-defined ABA- and BAB-type block copolymers of PDMAEMA and PCL2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 49, s. 25809-25818Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Triblock copolymers of ABA- and BAB-type consisting of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA, A) and poly(epsilon-caprolactone) (PCL, B) have successfully been prepared. PDMAEMA-b-PCL-b-PDMAEMA (ABA) and PCL-b-PDMAEMA-b-PCL (BAB) were synthesised by a combination of ring-opening polymerisation of epsilon-CL, atom transfer radical polymerisation of DMAEMA and end-group conversion, performed through either acylation or azide-alkyne "click" chemistry. All samples were analysed by size exclusion chromatography where it was found that the evaluation of PDMAEMA-containing polymers was difficult due to the thermoresponsivity of PDMAEMA, affecting the solubility of the polymer in the temperature range at which the SEC was operated. From differential scanning calorimetry measurements it was shown that the crystallinity could be altered by changing the order of the blocks; with PDMAEMA as the outer block (ABA), the inherent crystallinity of PCL was destroyed while with PCL as the outer block (BAB), the degree of crystallinity was in the same proximity as for a PCL homopolymer.

  • 8.
    Bu, Junfu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär Göran
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    The effect of NiO on the conductivity of BaZr0.5Ce0.3Y0.2O3-delta based electrolytes2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 67, s. 62368-62377Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of NiO on the sintering behaviors, morphologies and conductivities of BaZr0.5Ce0.3Y0.2O3-delta (BZCY532) based electrolytes were systematically investigated. 1 wt% NiO powder was added by different methods during the sample preparation: (i) added during ball-milling before a powder mixture calcination (named BZCY(Ni) 532), (ii) no NiO addition in the whole preparation procedure (named BZCY532) and (iii) added after a powder mixture calcination (named BZCY532(Ni)). The conductivities of these three kinds of dense BZCY532 ceramics were investigated in dry air, wet N-2 and wet H-2 atmospheres, respectively. Moreover, the electronic contributions to the total conductivities were also identified in a broad oxygen partial pressure range. According to the achieved results, it can be concluded that the dense BZCY(Ni) 532 ceramics showed the best enhanced oxygen and proton conductivities, followed by the BZCY532(Ni) and BZCY532 ceramics. Furthermore, the BZCY(Ni) 532 and BZCY532 ceramics showed a tiny electronic conductivity, when the testing temperatures were lower than 800 degrees C. However, the BZCY532(Ni) ceramics revealed an obvious electronic conduction when they were tested at temperatures of 600-800 degrees C. Therefore, it is preferable to add the NiO during powder preparation, which can lower the sintering temperature and also increase the conductivity of BZCY532-based electrolytes.

  • 9.
    Carrick, Christopher
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Larsson, Per A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Brismar, Hjalmar
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Aidun, Cyrus
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Native and functionalized micrometre-sized cellulose capsules prepared by microfluidic flow focusing2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 37, s. 19061-19067Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose capsules with average outer and inner radii of approximately 44 mu m and 29 mm respectively were prepared from cellulose dissolved in a mixture of lithium chloride and dimethylacetamide using a microfluidic flow focusing device (MFFD). The MFFD had three inlets where octane oil in a cellulose solution in silicone oil was used to produce a double emulsion containing a cellulose capsule. This technique enables the formation of capsules with a narrow size distribution which can be beneficial for drug delivery or controlled release capsules. In this respect, cellulose is a highly interesting material since it is known to cause no autoimmune reactions when used in contact with human tissue. Furthermore, by controlling the chemical properties of the cellulose, it is possible to trigger a swelling of the capsules and consequentially the release of an encapsulated substance, e. g. a model drug, when the capsule becomes exposed to an external stimulus. To demonstrate this, capsules were functionalized by carboxymethylation to be pH- responsive and to expand approximately 10% when subjected to a change in pH from 3 to 10. The diffusion constant of a model drug, a 4 kDa fluorescently labelled dextran, through the native capsule wall was estimated to be 6.5 X 10(-14) m(2) s(-1) by fitting fluorescence intensity data to Fick's second law.

  • 10. Chen, Bin
    et al.
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Wu, Wenjun
    Zha, Quanzheng
    Xie, Yongshu
    A novel trigeminal zinc porphyrin and corresponding porphyrin monomers for dye-sensitized solar cells2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 21, s. 10439-10449Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel trigeminal zinc porphyrin sensitizer (T) and two zinc porphyrin monomers (M1 and M2) were successfully designed and synthesized. The spectral, electrochemical, and photovoltaic properties of the porphyrin dyes were investigated. Compared with M1, the molecule of M2 has an additional aliphatic n-hexyloxyl chain at the meso-position of the porphyrin framework, and such a structure is favorable for the formation of a compact hydrophobic layer at the TiO2 surface and the retardation of the diffusion of I-3(-) ions into the nanoporous TiO2 electrode, resulting in more effective suppression of the charge recombination process and a higher V-oc. Meanwhile, M2 has larger IPCE values than those of M1, leading to the higher J(sc) value. Thus, the DSSC devices based on M2 demonstrated a relatively high power conversion efficiency of 5.77%, with the J(sc), V-oc and ff values of 13.93 mA cm(-2), 732 mV, and 0.566, respectively. Even though dye T has the highest molar absorption coefficients and multiple binding moieties, the corresponding power conversion efficiency is 2.30%, which is lower than those for M1 and M2. These observations may be ascribed to the low efficiency of the electron injection process caused by the isolation of the LUMOs from the anchoring carboxyl groups in addition to the lowest adsorption amount.

  • 11. Chen, Cheng
    et al.
    Yang, Xichuan
    Cheng, Ming
    Zhang, Fuguo
    Zhao, Jianghua
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Highly efficient organic dyes containing a benzopyran ring as a pi-bridge for DSSCs2013Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, nr 31, s. 12688-12693Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of novel organic dyes containing a benzopyran ring as a p-bridge have been designed and applied in dye-sensitized solar cells (DSSCs). This series of dyes show the excellent DSSCs' performance, due to their efficient light-to-photocurrent conversion in the region from 380 nm to 600 nm, with the highest IPCE values exceeding 90%. Through modification of the donor units, an efficiency as high as 7.5% has been achieved under standard light illumination (AM 1.5G, 100 mW cm(-2)) by the dye CC103.

  • 12.
    Chen, Fei
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gällstedt, M.
    Olsson, Rickard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    A novel chitosan/wheat gluten biofoam fabricated by spontaneous mixing and vacuum-drying2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 114, s. 94191-94200Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new type of chitosan and wheat gluten biofoam is presented. The pore structure achieved relied solely on the specific mixing and phase distribution when a film was cast from an aqueous mixture of chitosan/wheat gluten solution, in the absence of any chemical blowing agent, porogen or expanding gas. The foam was obtained when the liquid phase was removed by vacuum drying, without the need for the traditional freeze-drying that is frequently used for pore formation. Soft foam samples could be prepared with stiffnesses from 0.3 to 1.2 MPa and a high rebound resilience (64 and 94% at compressive strains of 80 and 20%, respectively). The foams were relatively ductile and did not require any plasticiser to allow for in-plane deformation (20% compression) and smaller bending. Only open pores with sizes of the order of 70-80 μm were observed by microscopy. The density of all the foams was ∼50 kg m-3, due to the high porosity (96% air). The foams showed a rapid and large uptake of both non-polar (limonene) and polar (water) liquids. When immersed in these liquids for 1 second, the maximum uptake recorded was 40 times the initial mass of the foam for limonene and 8 times for water.

  • 13. Chen, S.
    et al.
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Song, L.
    A fluorescent photochromic diarylethene based on naphthalic anhydride with strong solvatochromism2017Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 47, s. 29854-29859Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel "push-pull" diarylethene molecule consisting of an electron withdrawing ethene bridge (1,8-naphthalic anhydride) and two moderate electron donating side chains (2,5-dimethylthiophene) has been designed and synthesized. The photochromism study, together with density functional theory calculations, revealed that the molecule exhibits reversible fluorescence switching capacity upon photo-isomerization and remarkable solvatochromism with red shift of the fluorescence maximum by more than 150 nm owing to intramolecular charge transfer.

  • 14. Chen, Shangjun
    et al.
    Li, Wenlong
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Zhu, Wei-Hong
    Substitution effect on the photochromic properties of benzo[b]thiophene-1,1-dioxide based diarylethenes2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 106, s. 87626-87634Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Benzo[b]thiophene-1,1-dioxide based diarylethenes (DAEs), BTT-1 to BTT-4, containing methyl, phenyl, formyl and triphenylamine groups at the 5,5'-position of the thiophene rings have been developed for gaining an insight into the substituent effect on the absorption and photochromic properties. Electron-donating substituents, such as phenyl and triphenylamine groups, are found to be effective at shifting the absorption band to a longer wavelength and decreasing the cyclization quantum yield. The electron-withdrawing formyl group can increase the cyclization quantum yield, but it reduces the thermal stability of the ring-closed isomer to some extent. BTT-4 bearing a triphenylamine group shows the poorest fatigue resistance among these four compounds, which is possibly due to the larger extended pi-conjugation length in the ring-closed isomer. BTT-2 bearing a phenyl unit undergoes typical photochromic reaction not only in solution, but also in PMMA thin film and in bulky crystals with excellent fatigue resistance and thermal stability.

  • 15. Chen, Wei
    et al.
    Zhang, Zhiyun
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Su, Jianhua
    Highly sensitive detection of low-level water content in organic solvents and cyanide in aqueous media using novel solvatochromic AIEE fluorophores2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 16, s. 12191-12201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A great deal of effort has been devoted to develop easy-to-use fluorescent probes for detecting analytes due to their advantages in the field of chemo- and bio-sensing. Herein, two novel 2,2 '-biindenyl-based derivatives BDM and BDBM containing dicyanovinyl groups have been designed and synthesized, and are shown to possess the remarkable dual properties of solvatochromism and aggregation-induced emission enhancement (AIEE). Importantly, both of them are found to serve as fluorescent indicators for the qualitative and quantitative detection of low-level water in organic solvents. Meanwhile, both BDM and BDBM emit yellowish orange and orange fluorescence, respectively, in their aggregated states. Furthermore, with dicyanovinyl groups as the recognition sites, both compounds can act as colourimetric and fluorescent sensors for highly sensitive and selective detection of cyanide in aqueous media, and the apparent response signals can be observed by the naked eye even in the presence of various interference anions, promising practical applications for detecting cyanide in drinking water. Besides, optical spectroscopic techniques, NMR titration measurements, and density functional theory calculations are conducted to rationalize the sensing mechanisms of the two probes.

  • 16.
    Claudino, Mauro
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Thiol-ene coupling kinetics of D-limonene: a versatile 'non-click' free-radical reaction involving a natural terpene2013Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, nr 27, s. 11021-11034Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The free-radical photoinduced thiol-ene reaction between D-limonene, as renewable diolefinic substrate, and two mono-/tri-functional thiols (iso-tridecyl 3-mercaptopropionate and trimethylolpropane tris(3-mercaptopropionate)), has been investigated kinetically to define a relationship between alkene structure and reactivity. Separate thiol-ene solutions of the appropriate thiol in d-chloroform, supplemented with 1.0 wt% of DMPA (Irgacure 651), were subjected to polychromatic UV-irradiation and the chemical changes monitored discontinuously via H-1 NMR spectroscopy to quantify double bond conversion. The kinetic concentration profiles were modeled analytically and simulated in the application software COPASI for parameter estimation and to verify if the experimental data explained a suggested mechanistic scheme. Empirical results demonstrate that the external vinylidene bond of limonene reacts about 6.5 times faster with thiol than the internal trisubstituted 1-methyl-cyclohexene unsaturation. The selectivity observed for the two unsaturations was successfully explained by means of a simplified steady-state equation derived from the sequential reaction mechanism accounting for propagation and chain-transfer elementary steps with estimated rate coefficients. Kinetic modeling results attribute the difference in selectivity partially to steric impediments controlling thiyl-radical insertion onto the double bonds and predominantly to differences in relative energy between the two tertiary insertion carbon radical intermediates. The rate-limiting step was identified as the third chain-transfer hydrogen-abstraction reaction promoted by the second insertion carbon radical intermediate. High thiol-ene conversions were obtained in a timely fashion without major influence of secondary reactions demonstrating the suitability of this reaction for network forming purposes. The mechanistic and kinetic information collected can be used as a quantitative predictive tool to assess the potential use of D-limonene in thiol-ene network forming systems involving multifunctional alkyl ester 3-mercaptopropionates.

  • 17.
    Claudino, Mauro
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Utilizing thiol-ene coupling kinetics in the design of renewable thermoset resins based on D-limonene and polyfunctional thiols2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 20, s. 10317-10329Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An extended model is developed to predict the free-radical thiol-ene reaction dynamics between D-limonene, as a renewable diolefin, and a monothiol compound (iso-tridecyl 3-mercaptopropionate) in bulk liquid conditions. Thermally and photo-initiated reactions of the two monomers showed favored thiol-ene coupling at the exo-isopropenyl alkene structure when reacted at 1 : 1 and 1 : 0.5 mole ratios. Experimental kinetic data obtained from the two stoichiometries were well reproduced numerically via the simulation software COPASI by introducing a multi-route mechanistic scheme with propagation-chain-transfer steps accounting for primary (mono-additions) and secondary (di-addition) modes of coupling. The differences in intrinsic double-bond reactivity enable synthesis of limonene-terminated resins (mono-versus poly-disperse) as multifunctional network precursors. Off-stoichiometry manipulations in the initial mole ratio, assisted by numerical simulations, offer a convenient approach to visualize the overall reaction system kinetics irrespective of temporal effects, thus being regarded as an important guiding tool for chemists aiming at designing thiol-ene systems based on limonene.

  • 18. Crespo, Gaston A.
    et al.
    Bakker, Eric
    Dynamic electrochemistry with ionophore based ion-selective membranes2013Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, nr 48, s. 25461-25474Artikkel i tidsskrift (Fagfellevurdert)
  • 19.
    Dispenza, Clelia
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. Università Degli Studi di Palermo, Italy.
    Sabatino, M. A.
    Grimaldi, N.
    Mangione, M. R.
    Walo, M.
    Murugan, Eagambaram
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    On the origin of functionalization in one-pot radiation synthesis of nanogels from aqueous polymer solutions2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 4, s. 2582-2591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Radiation-engineered poly(N-vinyl pyrrolidone) nanogels are very interesting biocompatible nanocarriers for i.v. administration of therapeutics and contrast agents for bioimaging. The manufacturing process is fast and effective, it grants excellent control of particle size and simultaneous sterilization of the formed nanogels. Interestingly, primary amino groups and carboxyl groups, useful for (bio) conjugation, are also formed in a dose-dependent fashion. In this paper, by means of both numerical simulations and experiments, the origin of nanogel size control and functionalization is investigated. This understanding offers a new dimension for the design and production of radiation-sculptured multifunctional nanocarriers from aqueous solutions of polymers.

  • 20. Dobrota, Ana S.
    et al.
    Gutic, Sanjin
    Kalijadis, Ana
    Baljozovic, Milos
    Mentus, Slavko V.
    Skorodumova, Natalia V.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Uppsala Univ, Sweden.
    Pasti, Igor A.
    Stabilization of alkali metal ions interaction with OH-functionalized graphene via clustering of OH groups - implications in charge storage applications2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 63, s. 57910-57919Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Graphene synthesized by reduction of graphene oxide, depending on the degree of reduction, retains a certain amount of surface OH groups. Considering the surface OH groups/graphene layer system by means of density functional theory calculations, we evidenced the tendency of OH groups to cluster, resulting in enhanced system stability and no band gap opening. In the oxygen concentration range between 1.8 and 8.47 at%, with the addition of each new OH group, integral binding energy decreases, while differential binding energy shows the boost at even numbers of OH groups. Furthermore, we found that the clustering of OH groups over graphene basal plane plays a crucial role in enhancing the interactions with alkali metals. Namely, if alkali metal atoms interact with individual OH groups only, the interaction leads to an irreversible formation of MOH phase. When alkali atoms interact with clusters containing odd number of OH groups, a reversible transfer of an electron charge from the metal atom to the substrate takes place without OH removal. The strength of the interaction in general increases from Li to K. In an experimental investigation of a graphene sample which dominantly contains OH groups, we have shown that the trend in the specific interaction strength reflects to gravimetric capacitances measured in alkali metal chloride solutions. We propose that the charge stored in OH groups which interact with alkali metal cation and the pi electronic system of the graphene basal plane presents the main part of its pseudocapacitance.

  • 21.
    El-Seedi, Hesham R.
    et al.
    Uppsala Univ, Biomed Ctr, Dept Med Chem, Pharmacognosy Grp, Box 574, SE-75123 Uppsala, Sweden.;Jiangsu Univ, Coll Food & Biol Engn, Zhenjiang 212013, Jiangsu, Peoples R China.;Al Rayan Coll, Al Rayan Res & Innovat Ctr, Medina 42541, Saudi Arabia.;Menoufia Univ, Fac Sci, Dept Chem, Al Minufiyah, Egypt..
    El-Shabasy, Rehan M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi. Menoufia Univ, Fac Sci, Dept Chem, Al Minufiyah, Egypt.
    Khalifa, Shaden A. M.
    Karolinska Univ Hosp, Clin Res Ctr, Huddinge, Sweden.;Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, SE-10691 Stockholm, Sweden..
    Saeed, Aamer
    Quaid I Azam Univ, Dept Chem, Islamabad 45320, Pakistan..
    Shah, Afzal
    Univ Bahrain, Coll Sci, Dept Chem, Sakhir 32038, Bahrain..
    Shah, Raza
    Univ Karachi, Int Ctr Chem & Biol Sci, HEJ Res Inst Chem, Karachi 75270, Pakistan..
    Iftikhar, Faiza Jan
    Quaid I Azam Univ, Dept Chem, Islamabad 45320, Pakistan..
    Abdel-Daim, Mohamed M.
    Suez Canal Univ, Fac Vet Med, Pharmacol Dept, Ismailia 41522, Egypt..
    Omri, Abdelfatteh
    KAU, Ctr Excellence Bionosci Res, Jeddah 21589, Saudi Arabia.;KAU, Dept Biol Sci, Biotechnol Res Grp, Fac Sci, Jeddah 21589, Saudi Arabia..
    Hajrahand, Nahid H.
    KAU, Ctr Excellence Bionosci Res, Jeddah 21589, Saudi Arabia.;KAU, Dept Biol Sci, Biotechnol Res Grp, Fac Sci, Jeddah 21589, Saudi Arabia..
    Sabir, Jamal S. M.
    KAU, Ctr Excellence Bionosci Res, Jeddah 21589, Saudi Arabia.;KAU, Dept Biol Sci, Biotechnol Res Grp, Fac Sci, Jeddah 21589, Saudi Arabia..
    Zou, Xiaobo
    Jiangsu Univ, Coll Food & Biol Engn, Zhenjiang 212013, Jiangsu, Peoples R China..
    Halabi, Mohammed F.
    Al Rayan Coll, Al Rayan Res & Innovat Ctr, Medina 42541, Saudi Arabia..
    Sarhan, Wessam
    Zewail City Sci & Technol, Cairo, Egypt..
    Guo, Weisheng
    Guangzhou Med Univ, Affiliated Hosp 2, Translat Med Ctr, Guangzhou 510260, Guangdong, Peoples R China..
    Metal nanoparticles fabricated by green chemistry using natural extracts: biosynthesis, mechanisms, and applications2019Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 42, s. 24539-24559Artikkel, forskningsoversikt (Fagfellevurdert)
    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.

  • 22. Emam, A. N.
    et al.
    Mohamed, M. B.
    Girgis, E.
    Rao, K. Venkat
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hybrid magnetic-plasmonic nanocomposite: Embedding cobalt clusters in gold nanorods2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 44, s. 34696-34703Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We developed a method to fabricate hybrid magnetic-plasmonic nanorods (Au-Co NRs) via a modified seed mediated method. The only modification is to use cobalt ions instead of Au3+ in the preparation of the seed solution to obtain gold nanorods doped with Co clusters. By adjusting the amount of cobalt seed solution, Au-Co NRs of controlled aspect ratio can be obtained. The optical properties of the obtained Au-Co NRs were investigated and compared to those of the pure Au NRs. A slight shift and broadening were observed in the alloys compared to the pure ones, which was attributed to the presence of Co clusters leading to suppression of the dielectric properties. High resolution transmission electron microscopy (HRTEM) images indicate the existence of Co clusters in situ in the Au NR host and clearly show the metal-metal interface. The magnetic properties of the obtained Au-Co NRs increase as the concentration of dopant Co cluster seeds increases, as investigated by vibrating sample magnetometry (VSM). Our approach allows us to design nanomaterials of controlled shape, optical and magnetic properties which have many promising applications in tharanostics and photoelectronics.

  • 23.
    Fang, Mei
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Aristov, Andrey
    Rao, K. Venkat
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Kabashin, Andrei V.
    Belova, Lyubov
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Particle-free inkjet printing of nanostructured porous indium tin oxide thin films2013Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, nr 42, s. 19501-19507Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report a simple, low-cost, single-step inkjet printing method for the fabrication of nanostructured, highly transparent and conductive ITO films, which completely avoids the use of ITO particles in the fabrication process. In our method, the inks are formed from a liquid solution presenting a properly selected mixture of indium and tin acetates. After jet printing, the ink is decomposed during a subsequent annealing step, in which the released CO2 gas bubbles control the ITO nucleation process to provide a porous film texture. We show that the fabricated ITO films are highly crystalline, stoichiometric, and nanoporous with controlled porosity. Electrical measurements show relatively low resistivity values for the films (down to 0.029 Omega cm) comparable to those of the best ITO thin films fabricated by other methods. Optical ellipsometry tests demonstrate a relatively high refractive index (1.5-1.7) and high transparency of the films over a wide region of the spectrum ranging from 500 to 1700 nm. Since the method does not require any pre-fabricated ITO particles, masks or templates, and enables the deposition of films on substrates of various materials and shapes, it can be employed for fabrication of nanoporous ITO films for a diversity of applications, including solar cell, bio- and chemical sensing, etc.

  • 24.
    Farahani, Pooria
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Oliveira, Marcelo
    Fdez. Galvan, Ignacio
    Baader, Wilhelm J.
    A combined theoretical and experimental study onthe mechanism of spiro-adamantyl-1,2-dioxetanone decomposition2017Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, s. 17462-17472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1,2-Dioxetanones have been considered as model compounds for bioluminescence processes. Theunimolecular decomposition of these prototypes leads mainly to the formation of triplet excited stateswhereas in the catalysed decomposition of these peroxides singlet states are formed preferentially.Notwithstanding, these cyclic peroxides are important models to understand the general principles ofchemiexcitation as they can be synthesised, purified and characterised. We report here results ofexperimental and theoretical approaches to investigating the decomposition mechanism of spiroadamantyl-1,2-dioxetanone. The activation parameters in the unimolecular decomposition of thisderivative have been determined by isothermal kinetic measurements (30–70 C) and thechemiluminescence activation energy calculated from the correlation of emission intensities. Theactivation energy for peroxide decomposition proved to be considerably lower than thechemiluminescence activation energy indicating the existence of different reaction pathways for groundand excited state formation. These experimental results are compared with the calculations at thecomplete active space second-order perturbation theory (CASPT2), which reveal a two-step biradicalmechanism starting by weak peroxide bond breakage followed by carbon–carbon elongation. Thetheoretical findings also indicate different transition state energies on the excited and ground statesurfaces during the C–C bond cleavage in agreement with the experimental activation parameters.

  • 25.
    Finnveden, Maja
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Brännström, Sara
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Johansson, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Malmström, Eva
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Martinelle, Mats
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Industriell bioteknologi.
    Novel sustainable synthesis of vinyl ether ester building blocks, directly from carboxylic acids and the corresponding hydroxyl vinyl ether, and their photopolymerization2018Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, nr 44, s. 24716-24723Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Increased environmental awareness has led to a demand for sustainable, bio-based materials. Consequently, the development of new benign synthesis pathways utilizing a minimum of reaction steps and available bio-based building blocks is needed. In the present study, vinyl ether alcohols and functional carboxylic acids were used to synthesize bifunctional vinyl ether esters using the immobilized enzyme Candida antarctica lipase B as a catalyst. Vinyl ethers are attractive alternatives to (meth)acrylates due to low allergenic hazards, low toxicity, and fast polymerization; however, difficult synthesis limits the monomer availability. The synthesis was performed in one-pot and the described method was successful within a broad temperature range (22-90 degrees C) and in various organic solvents as well as in the bulk. The synthesis of different vinyl ether esters reached high conversions (above 90%) after less than 1 h and products were purified by removing the enzyme by filtration using only small amounts of acetone. This approach is a straightforward route to reach monomers with multiple types of functionalities that can be used as different photo-curable thermoset resins. In this work, this was demonstrated by polymerizing the monomers with cationic and radical UV-polymerization. By changing the functional carboxylic acids, the architecture of the final polymer can be tailored, herein demonstrated by two examples. In the developed versatile method, carboxylic acids can be used directly as acyl donors, constituting a more sustainable alternative to the carboxylic acid derivatives used today.

  • 26.
    Giummarella, Nicola
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Wallenberg Wood Science Center.
    Zhang, Liming
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Wallenberg Wood Science Center.
    Lawoko, Martin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Wallenberg Wood Science Center.
    Structural features of mildly fractionated lignin carbohydrate complexes (LCC) from spruce2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 48, s. 42120-42131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A protocol for the quantitative fractionation of lignin carbohydrate complexes (LCC) from wood under mild conditions has been developed. All operations occur at near-neutral pH conditions and low temperatures, in order to preserve the native structure. The protocol also achieved the fractionation of hemicelluloses of relatively high purity enabling for the first time estimates of hemicelluloses fractions not chemically bound to lignin in wood. 2D HSQC NMR was applied to decipher the structure of LCCs and was complemented by thioacidolysis-GC MS techniques. The carbohydrates linked to lignin in LCC are hemicelluloses, mainly arabinoglucuronoxylan (AGX) and galactoglucomannan (GGM). Benzylether (BE) and phenyl glycosidic (PG) linkages were detected. Significant structural differences in the lignin part of LCCs are also reported. The novelty of this work is that we report the first quantitative pH neutral protocol for LCC fractionation and detailed chemical analyses unveil important structural differences of relevance to fundamental knowledge in lignin polymerization and wood-based biorefineries.

  • 27. Golda-Cepa, M.
    et al.
    Aminlashgari, Nina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Kotarba, A.
    LDI-MS examination of oxygen plasma modified polymer for designing tailored implant biointerfaces2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 50, s. 26240-26243Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A versatile polymer coating for biomaterials was fabricated by the mild oxygen plasma treatment of Chemical Vapour Deposited (CVD) parylene C. The surface properties were tailored while the excellent protective properties of the bulk were preserved. The species, formed due to the plasma functionalisation, were fingerprinted by a novel Laser Desorption/Ionisation-Mass Spectrometry (LDI-MS) method. Improved osteosarcoma cells (line MG-63) attachment and viability on a modified surface were demonstrated.

  • 28. Golda-Cepa, M.
    et al.
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Kotarba, A.
    Development of crystalline-amorphous parylene C structure in micro-and nano-range towards enhanced biocompatibility: the importance of oxygen plasma treatment time2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 60, s. 48816-48821Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The crystalline-amorphous parylene C structure was fabricated by Chemical Vapour Deposited (CVD) and functionalised in the micro- and nano-range with the oxygen plasma treatment. The evolution of thermal stability, structure and surface biocompatibility of parylene C films as an effect of oxygen plasma treatment time were evaluated by means of thermogravimetric/differential thermal analysis (TG/DTA), X-Ray Diffraction (XRD) and cells adhesion tests (crystal violet assay, fluorescence microscopy). The results are epitomized by a crystalline-amorphous parylene C structural model. It was found that the time of oxygen plasma treatment is critical for adhesion of osteoblast cells with the optimum of 5-8 minutes.

  • 29.
    Gusev, Alexey
    et al.
    Russian Acad Sci, NS Kurnakov Inst Gen & Inorgan Chem, Moscow 119991, Russia. ryukova, Mariya.
    Braga, Elena
    Zamnius, Ekaterina
    Kiskin, Mikhail
    Kryukova, Mariya
    Baryshnikova, Alina
    Minaev, Boris F.
    Bohdan Khmelnytsky Natl Univ, Dept Chem & Nanomat Sci, UA-18031 Cherkassy, Ukraine.
    Baryshnikov, Gleb V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi. Bohdan Khmelnytsky Natl Univ, Dept Chem & Nanomat Sci, UA-18031 Cherkassy, Ukraine.
    Ågren, Hans
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Teoretisk kemi och biologi.
    Linert, Wolfgang
    Structure and excitation-dependent emission of novel zinc complexes with pyridyltriazoles2019Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 38, s. 22143-22152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of Zn(ii) complexes with 5-(4-R-phenyl)-3-(pyridin-2-yl)-1,2,4-triazoles have been synthesized and subsequently characterized by single crystal X-ray diffraction, H-1-NMR, FT-IR spectroscopy, elemental analyses, ESI-MS, and PXRD. The X-ray diffraction analyses revealed that the complexes have a similar molecular structure and their supramolecular frameworks are constructed by hydrogen bonds and pi center dot center dot center dot pi interaction scaffolds. Upon irradiation with UV light, the studied complexes display deep blue emission at 396-436 nm in the solid state. The compounds show an unexpected excitation-dependent emission phenomenon which is detected by a change in the emission color (from blue to yellow) upon increase of the excitation wavelength. The conducted quantum-chemical calculations indicate that supramolecular differences in the single-crystal architecture of the synthesized complexes play a crucial role for this photophysical behaviour.

  • 30. Ha, Minh Ngoc
    et al.
    Zhu, Feng
    Liu, Zhifu
    Wang, Lichao
    Liu, Linyan
    Lu, Guanzhong
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Shanghai Institute of Technology, China.
    Morphology-controlled synthesis of SrTiO3/TiO2 heterostructures and their photocatalytic performance for water splitting2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 25, s. 21111-21118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Different morphologies of SrTiO3/TiO2 heterostructures like nanocubes, nanoparticles, nanospheres, and nanofibers were synthesized via a facile hydrothermal process using TiO2 as both a template and precursor in Sr(OH)(2) solution. Their structure, interface and composition can be rationally tailored by simply adjusting the Sr(OH)(2)/TiO2 (Sr/Ti) mole ratios and the morphology of SrTiO3/TiO2 heterostructures can be controlled easily using TiO2 with different morphologies. A SrTiO3 crystal thin layer was grown on an anatase TiO2 substrate to fabricate a heterostructure interface contact between SrTiO3 and TiO2 and the lattice mismatch had an effect on the electrical transport properties. The SrTiO3/TiO2 heterostructures are beneficial for the fast separation of photogenerated electrons and holes so as to suppress the recombination of photogenerated electrons and holes at the interface of SrTiO3 and TiO2. Besides this, the different morphologies of the SrTiO3/TiO2 heterostructures allowing facile electron transfer, the hierarchical structure promoting mass transfer and allowing more light reflection and absorption, and the large specific surface area providing more reaction sites to facilitate the reactants to the desired oxidation places all together create a synergistic effect to improve the photocatalytic activity of the hierarchical SrTiO3/TiO2 heterostructures. Under the irradiation of UV light, in a water/methanol sacrificial reagent system, the SrTiO3/TiO2 NP heterostructures at a Sr/Ti mole ratio of 40% with the highest BET and smallest crystallite size achieve the highest photocatalytic activity generating 0.731 mmol of H-2. The SrTiO3/TiO2 heterostructures exhibit better photocatalytic activity by generating three times more H-2 than bare TiO2 and pure SrTiO3.

  • 31.
    Hassanzadeh, Salman
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Adolfsson, Karin H.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Controlling the cooperative self-assembly of graphene oxide quantum dots in aqueous solutions2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 71, s. 57425-57432Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fascinating 3D cooperative self-assembly behavior was observed for 2D graphene oxide quantum dots (GOQDs) in dilute and semi dilute aqueous solutions. In addition the optical properties could be tuned by controlling the supramolecular structures. While the electrostatic interactions between the charged single sheets were assigned as the main secondary interactions that were responsible for the supramolecular fine structures, the concentration, temperature, salt concentration and pH could tune the repulsive/attractive forces and the molecular binding between the GOQD sheets. The morphological studies combined with UV-Vis and fluorescence evaluations proved that after a slow nucleation step, elongation preceded radially by H-aggregate self-association of the GOQD monomers, forming the final porous spheres by radial growth of rods. The quenching properties of the self-associated-assembled GOQDs together with the excitation wavelengths of the GOQD solutions enabled tuning of the fluorescence intensity and color of the final solutions, which could be utilized for e.g. bioimaging and smart spectroscopy.

  • 32.
    Hatton, Fiona
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. University of Sheffield, United Kingdom.
    Engström, Joakim
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Forsling, Josefine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Biomimetic adsorption of zwitterionic-xyloglucan block copolymers to CNF: towards tailored super-absorbing cellulose materials2017Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 24, s. 14947-14958Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A biomimetic, facile approach to cellulose modification is the utilisation of self-adsorbing, naturally occurring biopolymers, such as the hemicellulose xyloglucan (XG). Herein, XG-block-poly(sulfobetaine methacrylate) (XG-b-PSBMA) zwitterionic block copolymers have been prepared and assessed for their ability to adsorb to cellulose, specifically cellulose nanofibrils (CNF). The polymers were synthesised using reversible addition-fragmentation chain-transfer (RAFT) polymerisation, employing an XG macromolecular RAFT agent (XG-RAFT), polymerising a sulfobetaine methacrylate (SBMA) under aqueous conditions. The incorporation of the XG block shifted the upper critical solution temperature (UCST) values to higher temperatures (20 and 30 °C) compared with the PSBMA homopolymers (17 and 22 °C) and the transition was also broadened. The adsorption of the polymers to a CNF surface was monitored using quartz crystal microbalance with dissipation monitoring (QCM-D), showing that the XG block enhanced the adsorption of the zwitterionic polymer. The formation of CNF-composite films was achieved utilising a facile vacuum filtration methodology, and the targeted compositions were confirmed by FT-IR and TGA analyses. The films exhibited high degrees of swelling in water, which were investigated at two different temperatures, 5 and 60 °C (below and above the polymer USCT values). These results highlight the advantage of using an XG block for the biomimetic modification of cellulose to form new cellulose-composite materials such as super-absorbing films.

  • 33. Hermans, J. J.
    et al.
    Keune, K.
    Van Loon, A.
    Corkery, Robert W.
    KTH.
    Iedema, P. D.
    Ionomer-like structure in mature oil paint binding media2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 96, s. 93363-93369Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Infrared spectra of samples from oil paintings often show metal carboxylate bands that are broader and shifted compared to those of crystalline metal soap standards (metal complexes of long-chain saturated fatty acids). Using quantitative attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), it is demonstrated that the broad metal carboxylate band is typically too intense to be explained by carboxylates adsorbed on the surface of pigment particles or disordered metal complexes of saturated fatty acids. The metal carboxylate species associated with the broad bands must therefore be an integral part of the polymerized binding medium. Small-angle X-ray scattering (SAXS) measurements on model ionomer systems based on linseed oil revealed that the medium contains ionic clusters similar to more classical ionomers. These structural similarities are very helpful in understanding the chemistry of mature oil paint binding media and the potential degradation mechanisms that affect oil paintings.

  • 34. Hong, Tao
    et al.
    Song, Heli
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Zhang, Weibing
    Xie, Yongshu
    Syntheses of mono- and diacylated bipyrroles with rich substitution modes and development of a prodigiosin derivative as a fluorescent Zn(II) probe2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 12, s. 6133-6140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The acylation of 2,20-bipyrrole with pentafluorobenzoyl chloride in the presence of AlCl3 afforded six acylated products with rich alpha-, beta-, beta(1)-, alpha,alpha'-, alpha,beta(')-, and alpha,beta(1)'-substitution modes for 1-6, respectively. Then, the alpha,alpha'-diacylated compound 4 was used to synthesize a prodigiosin derivative 9, which provides an alternative method for the syntheses of prodigiosin derivatives. Crystal structures of 1, 4 and 9 show interesting supramolecular dimers formed by multiple hydrogen bonds, O...pi interactions, as well as pi... pi interactions. Interestingly, 9 shows fluorescence turn-on probing behavior towards Zn2+ both in DMF and in DMF-HEPES, with high sensitivity and selectivity. The detection limit for Zn2+ in DMF was calculated to be 1.1 x 10(-8) M.

  • 35. Hu, M.
    et al.
    Yu, Z.
    Li, J.
    Jiang, X.
    Lai, J.
    Yang, X.
    Wang, M.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Low-cost solution-processed digenite Cu9S5 counter electrode for dye-sensitized solar cells2017Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 61, s. 38452-38457Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of low-cost alternatives to the commonly used but expensive platinum (Pt) catalyst in dye-sensitized solar cells (DSSCs) is important from a commercial point of view. In this work, Cu9S5 nanocrystalline film is fabricated directly onto a F-doped SnO2 (FTO) substrate by a solution-processed spin-coating method with low temperature post-treatment at 250 °C and it is further explored as a counter electrode (CE) material in DSSCs. The results from cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) disclose that Cu9S5 film exhibits a higher catalytic ability for the state-of-the-art cobalt(ii/iii) tris(bipyridyl) ([Co(bpy)3]2+/3+) redox system as compared to the widely used iodine-based electrolyte. Consequently, the DSSC devices based on the cobalt complex redox shuttles show a power conversion efficiency (PCE) of 5.7% measured at 100 mW cm-2 illumination (AM 1.5G), which is substantially higher than that of the iodine-based counterpart (3.9%). This has been the first presentation for the application of digenite copper sulfides as an electrocatalyst for the [Co(bpy)3]2+/3+ redox system in DSSCs. The present finding represents a promising solution for the development of alternative cost-effective CE materials for DSSCs in the future.

  • 36.
    Hua, Geng
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Olsen, Peter
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Franzen, Johan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Odelius, Karin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Anionic polycondensation and equilibrium driven monomer formation of cyclic aliphatic carbonates2018Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, nr 68, s. 39022-39028Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The current work explores the sodium hydride mediated polycondensation of aliphatic diols with diethyl carbonate to produce both aliphatic polycarbonates and cyclic carbonate monomers. The lengths of the diol dictate the outcome of the reaction; for ethylene glycol and seven other 1,3-diols with a wide array of substitution patterns, the corresponding 5-membered and 6-membered cyclic carbonates were synthesized in excellent yield (70-90%) on a 100 gram scale. Diols with longer alkyl chains, under the same conditions, yielded polycarbonates with an M-w ranging from 5000 to 16000. In all cases, the macromolecular architecture revealed that the formed polymer consisted purely of carbonate linkages, without decarboxylation as a side reaction. The synthetic design is completely solvent-free without any additional post purification steps and without the necessity of reactive ring-closing reagents. The results presented within provide a green and scalable approach to synthesize both cyclic carbonate monomers and polycarbonates with possible applications within the entire field of polymer technology.

  • 37.
    Hutchinson, Daniel J.
    et al.
    Department of Chemistry, University of Otago.
    Hanton, Lyall R.
    Department of Chemistry, University of Otago.
    Moratti, Stephen C.
    Department of Chemistry, University of Otago.
    The one pot synthesis of heterobimetallic complexes from a homoditopic pyrimidine–hydrazone ligand2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 28, s. 14550-14556Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The symmetrical, homoditopic, pyrimidine-hydrazone (pym-hyz) ligand L1 was used to synthesise three new heterobimetallic complexes, CuPbL1(ClO4)4, CuAgL1(SO3CF3)3, and CuZnL1(SO3CF3)4. Each of the complexes was produced in a one-pot reaction in CH3CN, and was isolated in high yield and purity simply by precipitation through the addition of diethyl ether. Analysis was carried out by IR, UV-Vis and ESMS spectroscopy, as well as microanalysis. Crystals were also grown for the purposes of X-ray diffraction studies, which yielded the structures [CuPbL1(ClO4)(CH3CN)2(H2O)](ClO4)3(1),[CuAgL1(SO3CF3)(CH3CN)2](SO3CF3)2$CH3CN (2), and CuZnL1(SO3CF3)2(CH3CN)(H2O)](SO3CF3)2$CH3CN (3), all of which were linear complexes containing a Cu(II) ion in one of the pym-hyz-py coordination sites, and either a Pb(II), Ag(I), or Zn(II) ion in the other.

  • 38.
    Håkansson, Karl
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Online determination of anisotropy during cellulose nanofibril assembly in a flow focusing device2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 24, s. 18601-18608Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to utilize the high strength (ultimate tensile strength = 3 GPa) [Saito et al., Biomacromolecules, 2012, 14, 248] and stiffness (Young's modulus = 130 GPa) [Sakurada et al., J. Polym. Sci., 1962, 57, 651] of cellulose nanofibrils in a macroscopic material or composite, the structure of the elongated fibrils in the material must be controlled. Here, cellulose nanofibrils in a dispersed state are partly aligned in a flow focusing device, whereafter the anisotropic nano-structure is locked by a dispersion-gel transition. The alignment process has been studied by Hakansson et al., [Nat. Commun., 2014, 5, 4018], however, the location of the phase transition as well as at which alignment (anisotropy) the fibrils were locked was not investigated. In this study, the degree of alignment is determined with small angle X-ray scattering experiments and the location of the phase change is measured with polarized light experiments. Furthermore, the anisotropy of the hydrogel thread is determined and the thread is seen to still be anisotropic after six months in a water bath.

  • 39. Höglin, Viktor
    et al.
    Cedervall, Johan
    Andersson, Mikael Svante
    Sarkar, Tapati
    Hudl, Matthias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. Uppsala University, Uppsala, Sweden.
    Nordblad, Per
    Andersson, Yvonne
    Sahlberg, Martin
    Phase diagram, structures and magnetism of the FeMnP1-xSix-system2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 11, s. 8278-8284Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The magnetic properties of the (Fe,Mn)(2)(P,Si)-system have been shown to be readily manipulated by small changes in composition. This study surveys the FeMnP1-xSix-system (0.00 <= x <= 1.00) reporting sample syntheses and investigations of crystallographic and magnetic properties using X-ray powder diffraction and magnetic measurements. Two single phase regions exist: the orthorhombic Co2P-type structure (x < 0.15) and the Fe2P-type structure (0.24 <= x < 0.50). Certain compositions have potential for use in magnetocaloric applications.

  • 40.
    Iranmanesh, Ida Sadat
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Ramachandraiah, Harisha
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Russom, Aman
    KTH, Skolan för bioteknologi (BIO), Proteomik och nanobioteknologi. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Wiklund, Martin
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    On-chip ultrasonic sample preparation for cell based assays2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 91, s. 74304-74311Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate an acoustophoresis method for size-based separation, isolation, up-concentration and trapping of cells that can be used for on-chip sample preparation combined with high resolution imaging for cell-based assays. The method combines three frequency-specific acoustophoresis functions in a sequence by actuating three separate channel zones simultaneously: zones for pre-alignment, size-based separation, and trapping. We characterize the mutual interference between the acoustic radiation forces between the different zones by measuring the spatial distribution of the acoustic energy density during different schemes of ultrasonic actuation, and use this information for optimizing the driving frequencies and voltages of the three utilized ultrasonic transducers attached to the chip, and the flow rates of the pumps. By the use of hydrodynamic defocusing of the pre-aligned cells in the separation zone, a cell population from a complex sample can be isolated and trapped with very high purity, followed by dynamic fluorescence analysis. We exemplify the method's potential by isolating A549 lung cancer cells from red blood cells with 100% purity, 92% separation efficiency, and 93% trapping efficiency resulting in a 130× up-concentration factor during 15 minutes of continuous sample processing through the chip. Furthermore, we demonstrate an on-chip fluorescence assay of the isolated cancer cells by monitoring the dynamic uptake and release of a fluorescence probe in individual trapped cells. The ability to combine isolation of individual cells from a complex sample with high-resolution image analysis holds great promise for applications in cellular and molecular diagnostics.

  • 41.
    Jawerth, Marcus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lawoko, Martin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lundmark, Stefan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Perstorp AB, Sweden.
    Pérez-Berumen, Catalina Maria
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Univ Autonoma Coahuila, Mexico.
    Johansson, Mats K G
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Allylation of a lignin model phenol: a highly selective reaction under benign conditions towards a new thermoset resin platform2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 98, s. 96281-96288Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The lack of aromatic material constituents derived from renewable resources poses a problem to meet the future demands of a more sustainable society. Lignin is the most abundant source of aromatic structures found in nature and is a highly interesting source for material applications. Development of controlled chemical modification routes of lignin structures are crucial in order to further develop this area. In this study allyl chloride is used to selectively modify a lignin phenol in the presence of other lignin functionalities, i.e. aliphatic hydroxyls and conjugated alkenes, under mild reaction conditions in quantitative yields. For this, coniferyl alcohol was used as a model compound in the present study. The modification was carried out in ethanol as the synthesis media. Studies on the effect of reaction time and temperature revealed optimum conditions allowing for a quantitative yield without any detectable levels of byproducts as studied with NMR, FT-IR and FT-Raman. The thermal stability of the formed product was determined to be up to at least 160 degrees C through DSC measurements. In addition, as a proof of concept, the use of the allylated monomer to form crosslinked films using free radical thiol-ene polymerization was demonstrated.

  • 42.
    Johansson Salazar-Sandoval, Eric
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. SP Technical Research Institute of Sweden.
    Aguirre, Miren
    Paulis, Mari A.
    Leiza, Jose R.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Ahniyaz, Anwar
    Radical initiator modified cerium oxide nanoparticles for polymer encapsulation via grafting from the surface2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 106, s. 61863-61868Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present paper describes a versatile route to modify and stabilize ceria nanoparticles with a radical initiator, 4,4'-azobis(4-cyanovaleric acid) (ACVA), allowing a strong interface to be formed via grafting of polymers from the surface. This leads to the successful encapsulation of cerium oxide nanoparticles in a poly(methyl methacrylate) matrix. The interaction between the radical initiator and the surface of ceria is studied by FTIR spectroscopy where a consistent shift of the carboxylate band unequivocally demonstrates that the carboxylate groups of this acidic initiator complex the cerium ions on the ceria surface by means of strong and stable ionic bonding.

  • 43.
    Josefsson, Leila
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Cronhamn, Melker
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Ekman, Malin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Widehammar, Hugo
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Emmer, Åsa
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Lendel, Christofer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Structural basis for the formation of soy protein nanofibrils2019Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 11, s. 6310-6319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Amyloid-like protein nanofibrils (PNFs) can assemble from a range of different proteins including disease-associated proteins, functional amyloid proteins and several proteins for which the PNFs are neither related to disease nor function. We here examined the core building blocks of PNFs formed by soy proteins. Fibril formation at pH 2 and 90 degrees C is coupled to peptide hydrolysis which allows isolation of the PNF-forming peptides and identification of them by mass spectrometry. We found five peptides that constitute the main building blocks in soy PNFs, three of them from the protein b-conglycinin and two from the protein glycinin. The abilities of these peptides to form PNFs were addressed by amyloid prediction software and by PNF formation of the corresponding synthetic peptides. Analysis of the structural context in the native soy proteins revealed two structural motifs for the PNF-forming peptides: (i) so-called b-arches and (ii) helical segments involved in quaternary structure contacts. However, the results suggest that neither the native structural motifs nor the protein of origin defines the morphology of the PNFs formed from soy protein isolate.

  • 44. Kanhere, Pushkar
    et al.
    Chakraborty, Sudip
    Rupp, Caroline J.
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Sweden.
    Chen, Zhong
    Substitution induced band structure shape tuning in hybrid perovskites (CH3NH3Pb1-xSnxI3) for efficient solar cell applications2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 130, s. 107497-107502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic-inorganic hybrid perovskite compounds such as CH3NH3PbI3 hold a great potential for low cost photovoltaic devices. Though CH3NH3PbI3 possesses fundamental properties favorable for solar energy harvesting, environmentally safe materials with higher energy efficiency are needed for practical applications. Replacement of lead by tin is a promising solution and investigating the fundamental properties of lead and tin mixed halides is essential. In this article, we have reported electronic and optical properties by employing Density Functional Theory based first principles calculations of Sn doped methyl ammonium lead halide, CH3NH3Pb1-xSnxI3 (x = 0, 0.25, 0.5, 0.75, 1.0). Our results reveal that tin doping narrows the optical band gap allowing absorption of visible light up to 850 nm. Tin doping at Pb sites primarily affects the composition and nature of the valence band maximum. Tin 5p induced electronic states are highly delocalized in nature and are likely to improve the mobility and possible exciton diffusion lengths of holes. Based on the results of this study, 50% Sn doping could to be useful for enhanced performance of perovskite based photovoltaics.

  • 45. Karaush, Nataliya N.
    et al.
    Bondarchuk, Sergey V.
    Baryshnikov, Gleb V.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Bohdan Khmelnytsky National University, Ukraine.
    Minaeva, Valentina A.
    Sun, Wen-Hua
    Minaev, Boris F.
    Computational study of the structure, UV-vis absorption spectra and conductivity of biphenylene-based polymers and their boron nitride analogues2016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 55, s. 49505-49516Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, we calculated the electronic and spectral properties of the one- and two-dimensional carbon and boron nitride materials composed of four-, six- and eight-membered rings (the (4, 6, 6, 8) topology) on the basis of density functional theory, including the band structure analysis for the infinite structures. We found that biphenylene-based two-dimensional (2D) sheets and zigzag-type biphenylene-based one-dimensional (1D) ribbons exhibit a semi-metal character. At the same time, the armchair 1D biphenylene-based ribbons possess a narrow-band-gap structure, while boron nitride 2D sheets, 1D zigzag- and armchair-type ribbons exhibit a wide-band-gap semiconducting nature. Simple single-point calculations with a periodic boundary condition generally underestimate the band-gap values in comparison with band structure calculations accounting for the supercell optimization. But in the general case, both approaches provide a correct explanation of the band-gap value. In this work, we also performed for the first time computational modelling of a novel porous biphenylene-based wide-band-gap carbon allotrope, which demonstrated the complexation ability relative to metal atoms forming the metal-carbon intercalates.

  • 46.
    Kuang, Guanglin
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Zhou, Yang
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Zou, Rongfeng
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Halldin, C.
    Nordberg, A.
    Långström, B.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. Siberian Federal University, Russian Federation.
    Tu, Yaoquan
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Characterization of the binding mode of the PET tracer [18F]ASEM to a chimera structure of the α7 nicotinic acetylcholine receptor2017Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 32, s. 19787-19793Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The α7 nicotinic acetylcholine receptor (α7-nAChR) is assumed to be implicated in a variety of neurological disorders, such as schizophrenia and Alzheimer's disease (AD). The progress of these disorders can be studied through imaging α7-nAChR with positron emission tomography (PET). [18F]ASEM is a novel and potent α7-nAChR PET radioligand showing great promise in recent tests. However, the mechanism of the molecular interaction between [18F]ASEM and α7-nAChR is still unclear. In this paper, the binding profile of [18F]ASEM to a chimera structure of α7-nAChR was investigated with molecular docking, molecular dynamics, and metadynamics simulation methods. We found that [18F]ASEM binds at the same site as the crystallized agonist epibatidine but with a different binding mode. The dibenzo[b,d]thiophene ring has a different orientation compared to the pyridine ring of epibatidine and has van der Waals interactions with residues from loop C on one side and π-π stacking interaction with Trp53 on the other side. The conformation of Trp53 was found to have a great impact on the binding of [18F]ASEM. Six binding modes in terms of the side chain dihedral angles χ1 and χ2 of Trp53 were discovered by metadynamics simulation. In the most stable binding mode, Trp53 adopts a different conformation from that in the crystalline structure and has a rather favorable π-π stacking interaction with [18F]ASEM. We believe that these discoveries can be valuable for the development of novel PET radioligands.

  • 47. Kuktaite, R.
    et al.
    Plivelic, T. S.
    Türe, Hasan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gällstedt, M.
    Marttila, S.
    Johansson, E.
    Changes in the hierarchical protein polymer structure: Urea and temperature effects on wheat gluten films2012Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 2, nr 31, s. 11908-11914Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding bio-based protein polymer structures is important when designing new materials with desirable properties. Here the effect of urea on the wheat gluten (WG) protein structure in WG-urea films was investigated. Small-angle X-ray scattering indicated the formation of a hexagonal close-packed (HCP) hierarchical structure in the WG-urea materials. The HCP structure was influenced significantly by the urea concentration and processing conditions. The interdomain distance d I between the HCP scattering objects increased with increasing content of urea and the objects seemed to be oriented in the extrusion direction. Additionally, the effect of temperature on the HCP structure was studied and it was shown that at ≥55°C the HCP structure disappeared. Transmission electron microscopy revealed a rather denatured pattern of both HMW-glutenins and gliadins in the WG-urea films. The molecular packing of the WG protein polymer can be highly affected by an additive and the processing method used.

  • 48. Kumavat, Sandip
    et al.
    Chakraborty, Sudip
    Rahane, Amol B.
    Deshpande, Mrinalini D.
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Uppsala University, Sweden.
    Time dependent DFT investigation of the optical response in pristine and Gd doped Al2O32016Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, nr 76, s. 72537-72543Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The optical absorption spectra and static polarizabilities for the lowest energy configurations of Al2O3 and Gd doped (Al2O3)(n) clusters (n = 1-10) are investigated based on the time-dependent density functional theory (TDDFT) formalism. The polarizabilities of (Al2O3)(n), GdAl2n-1O3n, and Gd2Al2n-2O3n clusters decrease with the increase in size (n) of the cluster. On the other hand, the polarizability of the pristine system increases with the Gd concentration. A systematic study of the optical band gap and HOMO-LUMO gap change for different cluster sizes and Gd concentrations has been envisaged. This could be quite useful from the application perspective of band gap tuning with respect to the cluster size. The study reveals the dependence of both the optical gap and the optical spectra on the geometry, size of the cluster and number of Gd atoms. It is observed that the optical gap oscillates with an increase in the cluster size. With an increase in the number of Gd atoms, a red shift is observed in the optical spectra compared to the pristine system. Interestingly, smooth transitions from discrete to quasi-continuous optical spectra have also been predicted with an increase in size. The simulated spectra exhibit long absorption tails extending deep into the region of lower transition energies.

  • 49.
    Larsson, Emma
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Boujemaoui, Assya
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Thermoresponsive cryogels reinforced with cellulose nanocrystals2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 95, s. 77643-77650Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein, we report the first study of thermoresponsive cryogels with cellulose nanocrystals (CNCs) incorporated into the structure. Free radical polymerization was utilized to synthesize cryogels of poly(N-isopropylacrylamide) (PNIPAAm), resulting in thermoresponsive gels after the cryo-polymerization. Two types of CNCs were investigated: one which had reactive vinyl groups on the surface, enabling covalent incorporation and crosslinking with the cryogel network; and one which had no reactive groups on the surface, rendering it physically embedded in the network. The degree of crosslinking of the cryogels was controlled by varying the addition of N,N'-methylenebisacrylamide (MBAm). The cryogels were analyzed by FE-SEM and were all found to be macroporous. The morphology of the gels was largely dependent on the reaction conditions and the presence of CNC. The swelling properties of the freeze-dried gels were investigated and all gels exhibited a thermoresponsive behavior. Our study showed that the incorporation of CNCs is an effective method to alter both the morphologies and the mechanical properties of a cryogel, although the final properties of the cryogels depend on several different parameters. Due to the complexity of the system, a clear trend regarding the CNC incorporation is difficult to conclude, but compression testing showed that a cryogel having 1 wt% of crosslinkable CNC was far superior to the other gels in terms of mechanical properties, exhibiting that the presence of crosslinkable groups on the surface of CNCs could have a large influence over the final properties.

  • 50. Li, J.
    et al.
    Yang, X.
    Yu, Z.
    Gurzadyan, G. G.
    Cheng, Ming
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Zhang, F.
    Cong, Jiayan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Wang, W.
    Wang, H.
    Li, X.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Wang, M.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Efficient dye-sensitized solar cells with [copper(6,6′-dimethyl-2,2′-bipyridine)2]2+/1+ redox shuttle2017Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, nr 8, s. 4611-4615Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The [copper(6,6′-dimethyl-2,2′-bipyridine)2]2+/1+ ([Cu(dmbp)2]2+/1+) redox couple, which possesses a distorted tetragonal geometry of a Cu(i) complex crystal and a distorted tetrahedral coordination geometry of Cu(ii) complex crystal, has been developed as a redox mediator in dye-sensitized solar cells (DSSCs). The energy of loss for dye regeneration was reduced with a very low but sufficient driving force of only 0.11 eV. A distinct increase in open-circuit voltage (VOC) was achieved and a remarkable power conversion efficiency of 10.3% was afforded at 100 mW cm−2 under AM 1.5G condition.

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