The Experts below are selected from a list of 30183 Experts worldwide ranked by ideXlab platform
Herbert Sixta - One of the best experts on this subject based on the ideXlab platform.
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water induced crystallization and nano scale spinodal decomposition of cellulose in nmmo and ionic liquid dope
Cellulose, 2019Co-Authors: Yoshiharu Nishiyama, Shirin Asaadi, Patrik Ahvenainen, Herbert SixtaAbstract:We followed the cellulose structure formation induced by water diffusion into Lyocell dopes based on both N-Methylmorpholine N-oxide (NMMO) and 1,5-diazabicyclo[4.3.0]non-5-ene acetate ([DBNH][OAc], by using scanning simultaneous small- and wide-angle Scattering (SAXS-WAXS) experiment along the diffusion gradient. The water content at each point was estimated from the wide-angle Scattering Profile, giving a binary diffusion constant of the order of 5 × 10−10 m2/sec. In the case of the cellulose solution in NMMO monohydrate, diffraction peaks corresponding to cellulose II appeared concomitantly with the increase in small angle Scattering features indicative of nanofibril formation. In the cellulose solution in the ionic liquid, an increase in small angle Scattering intensity with the progression of water content appeared at Scattering vector q = 0.015 A−1 corresponding to a correlation length of about 40 nm, indicative of nanometric spinodal decomposition preceding the coagulation process, though no crystalline peak appeared in the wide-angle Scattering.
F Peiro - One of the best experts on this subject based on the ideXlab platform.
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resolving material specific structures within fe o γ mn o core shell nanoparticles using anomalous small angle x ray Scattering
ACS Nano, 2013Co-Authors: Kathryn Krycka, J A Borchers, German Salazaralvarez, Alberto Lopezortega, Marta Estrader, Sonia Estrade, E Winkler, R D Zysler, Jordi Sort, F PeiroAbstract:Here it is demonstrated that multiple-energy, anomalous small-angle X-ray Scattering (ASAXS) provides significant enhancement in sensitivity to internal material boundaries of layered nanoparticles compared with the traditional modeling of a single Scattering energy, even for cases in which high Scattering contrast naturally exists. Specifically, the material-specific structure of monodispersed Fe3O4|γ-Mn2O3 core|shell nanoparticles is determined, and the contribution of each component to the total Scattering Profile is identified with unprecedented clarity. We show that Fe3O4|γ-Mn2O3 core|shell nanoparticles with a diameter of 8.2 ± 0.2 nm consist of a core with a composition near Fe3O4 surrounded by a (MnxFe1–x)3O4 shell with a graded composition, ranging from x ≈ 0.40 at the inner shell toward x ≈ 0.46 at the surface. Evaluation of the Scattering contribution arising from the interference between material-specific layers additionally reveals the presence of Fe3O4 cores without a coating shell. Finally,...
Yoshiharu Nishiyama - One of the best experts on this subject based on the ideXlab platform.
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water induced crystallization and nano scale spinodal decomposition of cellulose in nmmo and ionic liquid dope
Cellulose, 2019Co-Authors: Yoshiharu Nishiyama, Shirin Asaadi, Patrik Ahvenainen, Herbert SixtaAbstract:We followed the cellulose structure formation induced by water diffusion into Lyocell dopes based on both N-Methylmorpholine N-oxide (NMMO) and 1,5-diazabicyclo[4.3.0]non-5-ene acetate ([DBNH][OAc], by using scanning simultaneous small- and wide-angle Scattering (SAXS-WAXS) experiment along the diffusion gradient. The water content at each point was estimated from the wide-angle Scattering Profile, giving a binary diffusion constant of the order of 5 × 10−10 m2/sec. In the case of the cellulose solution in NMMO monohydrate, diffraction peaks corresponding to cellulose II appeared concomitantly with the increase in small angle Scattering features indicative of nanofibril formation. In the cellulose solution in the ionic liquid, an increase in small angle Scattering intensity with the progression of water content appeared at Scattering vector q = 0.015 A−1 corresponding to a correlation length of about 40 nm, indicative of nanometric spinodal decomposition preceding the coagulation process, though no crystalline peak appeared in the wide-angle Scattering.
Kathryn Krycka - One of the best experts on this subject based on the ideXlab platform.
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resolving material specific structures within fe o γ mn o core shell nanoparticles using anomalous small angle x ray Scattering
ACS Nano, 2013Co-Authors: Kathryn Krycka, J A Borchers, German Salazaralvarez, Alberto Lopezortega, Marta Estrader, Sonia Estrade, E Winkler, R D Zysler, Jordi Sort, F PeiroAbstract:Here it is demonstrated that multiple-energy, anomalous small-angle X-ray Scattering (ASAXS) provides significant enhancement in sensitivity to internal material boundaries of layered nanoparticles compared with the traditional modeling of a single Scattering energy, even for cases in which high Scattering contrast naturally exists. Specifically, the material-specific structure of monodispersed Fe3O4|γ-Mn2O3 core|shell nanoparticles is determined, and the contribution of each component to the total Scattering Profile is identified with unprecedented clarity. We show that Fe3O4|γ-Mn2O3 core|shell nanoparticles with a diameter of 8.2 ± 0.2 nm consist of a core with a composition near Fe3O4 surrounded by a (MnxFe1–x)3O4 shell with a graded composition, ranging from x ≈ 0.40 at the inner shell toward x ≈ 0.46 at the surface. Evaluation of the Scattering contribution arising from the interference between material-specific layers additionally reveals the presence of Fe3O4 cores without a coating shell. Finally,...
Peter Lindblad - One of the best experts on this subject based on the ideXlab platform.
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oligomerization and characteristics of phosphoenolpyruvate carboxylase in synechococcus pcc 7002
Scientific Reports, 2020Co-Authors: Claudia Durall, Sandesh Kanchugal P, Maria Selmer, Peter LindbladAbstract:Phosphoenolpyruvate carboxylase (PEPc) is an essential enzyme in plants. A photosynthetic form is present both as dimer and tetramer in C4 and CAM metabolism. Additionally, non-photosynthetic PEPcs are also present. The single, non-photosynthetic PEPc of the unicellular cyanobacterium Synechococcus PCC 7002 (Synechococcus), involved in the TCA cycle, was examined. Using size exclusion chromatography (SEC) and small angle X-ray Scattering (SAXS), we observed that PEPc in Synechococcus exists as both a dimer and a tetramer. This is the first demonstration of two different oligomerization states of a non-photosynthetic PEPc. High concentration of Mg2+, the substrate PEP and a combination of low concentration of Mg2+ and HCO3- induced the tetramer form of the carboxylase. Using SEC-SAXS analysis, we showed that the oligomerization state of the carboxylase is concentration dependent and that, among the available crystal structures of PEPc, the Scattering Profile of PEPc of Synechococcus agrees best with the structure of PEPc from Escherichia coli. In addition, the kinetics of the tetramer purified in presence of Mg2+ using SEC, and of the mixed population purified in presence of Mg2+ using a Strep-tagged column were examined. Moreover, the enzyme showed interesting allosteric regulation, being activated by succinate and inhibited by glutamine, and not affected by either malate, 2-oxoglutarate, aspartic acid or citric acid.
