| 1. |
- Chen, Yong, et al.
(författare)
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Metformin, an AMPK Activator, Inhibits Activation of FLSs but Promotes HAPLN1 Secretion
- 2020
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Ingår i: Molecular therapy. Methods & clinical development. - : Elsevier BV. - 2399-6951 .- 2329-0501. ; 17, s. 1202-1214
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Tidskriftsartikel (refereegranskat)abstract
- AMP-activated protein kinase (AMPK) is essential for maintaining energy balance and has a crucial role in various inflammatory pathways. In this study, AMPK levels positively correlated with many inflammatory indexes in rheumatoid arthritis (RA) patients, especially in the affected synovium. In RA sera, a positive correlation between phosphorylated (p-)AMPK-α1 levels and DAS28 (disease activity score 28) activity (r = 0.270, p < 0.0001) was found. Similarly, a positive correlation was observed between AMPK-α1 and tumor necrosis factor α (TNF-α) levels (r = 0.460, p = 0.0002). Differentially expressed genes between osteoarthritis (OA) and RA synovium from NCBI GEO profiles and our RNA sequencing data suggested activation of metabolic pathways specific to RA-fibroblast-like synoviocytes (FLSs). AMPK-α1 was highly expressed in the synovium of RA but not OA patients. An AMPK activator, metformin, inhibited FLS proliferation at higher but not lower concentrations, whereas the inhibitor dorsomorphin promoted the proliferation of RA-FLSs. Interestingly, both metformin and dorsomorphin inhibited the migration of RA-FLSs. After metformin treatment, expression of interleukin 6 (IL-6), TNF-α, and IL-1β were significantly downregulated in RA-FLSs; however, increased expression of p-AMPK-α1, protein kinase A (PKA)-α1, and HAPLN1 (hyaluronan and proteoglycan link protein 1) was observed. Increased levels of HAPLN1 in RA-FLSs by an AMPK activator could potentially be beneficial in protecting the joints. Hence, our results demonstrate the potential of an AMPK activator as a therapeutic for RA.
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| 2. |
- Cho, Kanghee, et al.
(författare)
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Mesopore generation by organosilane surfactant during LTA zeolite crystallization investigated by high-resolution SEM and Monte Carlo simulation
- 2011
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Ingår i: Solid State Sciences. - : Elsevier BV. - 1293-2558 .- 1873-3085. ; 13:4, s. 750-756
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Tidskriftsartikel (refereegranskat)abstract
- The crystallization of LTA zeolite under a hydrothermal synthesis condition that contained a quaternary ammonium-type organosilane surfactant was studied with X-ray powder diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and Monte Carlo simulation of the crystal growth. The hydrothermal reaction products were collected at various crystallization times, and investigated with XRD and HRSEM. The HRSEM images of the final zeolite products were taken as synthesized and also after cross-sectioning with an argon ion beam. The HRSEM investigation revealed presence of a disordered network of mesoporous channels that penetrated the microporous zeolite crystal. Unless the loading of the surfactant was exceedingly high, the microporous zeolite particles exhibited truncated cubic morphologies that were almost like single crystals, despite penetration by the mesopores. The outline of the zeolite particle became progressively rounded as the mesoporosity was increased according to the surfactant loading. The mesoporosity in the zeolite crystals was well maintained against crystal-ripening processes for 6 d. This result supports the fact that the organosilane surfactant micelles became incorporated inside the zeolite crystal as a mesopore generator during the crystallization process. Data from Monte Carlo simulation agreed with these experimental results.
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| 3. |
- Garcia-Bennett, Alfonso E, et al.
(författare)
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Bicontinuous Cubic Mesoporous Materials with Biphasic Structures
- 2011
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 17:48, s. 13510-13516
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Tidskriftsartikel (refereegranskat)abstract
- The replication of amphiphilic systems within an inorganic silica matrix allows the study of the fundamental properties of mesostructural changes, that is, kinetic and structural parameters. Herein we report a detailed study of the transition between cubic bicontinuous mesostructure with space groups Ia$\bar 3$d and Pn$\bar 3$m symmetry, which are associated with the minimal G and D surfaces, respectively. The transition may be induced through micellar swelling of the anionic amphiphilic surfactant N-lauroyl alanine by trimethylbenzene. Rich kinetic behaviour is observed and has been exploited to prepare particles with biphasic structures. Transmission electron microscopy evidence indicates that there is epitaxial growth from one mesostructure to the other involving the [111] and [110] orientations of the Ia$\bar 3$d and Pn$\bar 3$m symmetry structures, respectively. From kinetic studies, we show that the formation of the Ia$\bar 3$d mesophase is preceded by a hexagonal phase (plane group p6mm) and an epitaxial relationship has been observed involving the sixfold or $\bar 3$ axis orientations of both structures. Our data suggests that the Pn$\bar 3$m mesostructure is kinetically stable at low temperatures whereas the Ia$\bar 3$d mesostructure is the more stable structure after prolonged periods of hydrothermal treatment. We present evidence from transmission electron microscopy and small-angle X-ray diffractograms and also electron crystallography modelling of the unit cells at particular points in the structural change.
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| 4. |
- Garcia-Martinez, Javier, et al.
(författare)
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Evidence of Intracrystalline Mesostructured Porosity in Zeolites by Advanced Gas Sorption, Electron Tomography and Rotation Electron Diffraction
- 2014
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Ingår i: ChemCatChem. - : Wiley. - 1867-3880 .- 1867-3899. ; 6:11, s. 3110-3115
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Tidskriftsartikel (refereegranskat)abstract
- The small size of micropores (typically <1 nm) in zeolites causes slow diffusion of reactant and product molecules in and out of the pores and negatively impacts the product selectivity of zeolite based catalysts, for example, fluid catalytic cracking (FCC) catalysts. Size-tailored mesoporosity was introduced into commercial zeolite Y crystals by a simple surfactant-templating post-synthetic mesostructuring process. The resulting mesoporous zeolite Y showed significantly improved product selectivity in both laboratory testing and refinery trials. Advanced characterization techniques such as electron tomography, three-dimensional rotation electron diffraction, and high resolution gas adsorption coupled with hysteresis scanning and density functional theory, unambiguously revealed the intracystalline nature and connectivity of the introduced mesopores. They can be considered as molecular highways that help reactant and product molecules diffuse quickly to and away from the catalytically active sites within the zeolite crystals and, thus, shift the selectivity to favor the production of more of the valuable liquid fuels at reduced yields of coke and unconverted feed.
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| 5. |
- Graves, Alex, et al.
(författare)
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An experimental and theoretical investigation on Ti-5553/WC-Co(6%) chemical interactions during machining and in diffusion couples
- 2023
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 516-517, s. 204604-
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Tidskriftsartikel (refereegranskat)abstract
- Chemical interactions that drive crater wear in turning are often studied using diffusion couples where the tool and workpiece are fixed. In contrast, in actual turning, there is a constant supply of new workpiece material at the tool-chip interface. In this work, diffusion simulations of a WC-Co(6%) and Ti-5Al-5V system were conducted, with constant replenishment of titanium at the interface (open system) and a fixed amount of material (closed system). The simulations showed that the formation of W(bcc), ry-phase, and TiC is dependent on the activity of C and the permeability of Co and C in titanium. Scanning and transmission electron microscopy-based techniques were used to analyse a Ti-5Al-5V-5Mo-3Cr and WC-Co(6%) diffusion couple and a worn WC-Co(6%) insert. The sequence of phases in the closed system simulation was similar to that observed in the diffusion couple. The open system simulation indicated that W(bcc) can form at WC-WC boundaries (where Co is low) within the subsurface of a WC-Co(6%) that has adhered titanium, and at the WC/Ti interface. Additionally, high densities of stacking faults and dislocations were found within subsurface WC grains, indicating a significant reduction of the tool's integrity.
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| 6. |
- Han, Lu, et al.
(författare)
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Silica-Based Nanoporous Materials
- 2014
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Ingår i: Zeitschrift für Anorganische und Allgemeines Chemie. - : Wiley. - 0044-2313 .- 1521-3749. ; 640:3-4, s. 521-536
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Forskningsöversikt (refereegranskat)abstract
- Ordered nanoporous structures are among the most fascinating and industrially important materials currently in use. The archetypal zeolite material has now been joined by an eclectic array of new structures that exhibit porosity over a wide range of length scales and with order/disorder expressed in a multitude of ways. This raises the bar in terms of characterization and extends a real challenge to the scientific community to fully understand the properties and potential future applications of such materials. In this review we discuss the importance of modern microscopy tools combined with diffraction in this endeavour and show how the details of even the most complex quasi-crystalline nanoporous architectures can be elucidated. We show by using the appropriate spherical aberration (C-s) corrections in scanning transmission electron microscopy it is possible to decipher all the individual silicon and aluminum atoms in a zeolite structure. Automated routines for using large electron diffraction datasets for crystal structure determination of nanocrystals is described making the need for large single crystal synthesis less-and-less important. The power of complementary combinations of surface tools such as atomic force microscopy and high-resolution scanning electron microscopy is discussed to elucidate crystal growth mechanisms. For mesoporous materials synthesized from self-organized organic mesophases electron microscopy reveals the details of the complex hierarchy of porosity so crucial for the functional performance of the structure.
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| 7. |
- Lin, C., et al.
(författare)
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Nano Pores Evolution in Hydroxyapatite Microsphere during Spark Plasma Sintering
- 2011
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Ingår i: Science of Sintering. - 0350-820X. ; 43:1, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- Micron-spherical granules of hydroxyapatite (HAp) nanoparticles were prepared by powder granulation methods. Through subsequent sintering, porous HAp microspheres with tailored pore and grain framework structures were obtained. Detailed microstructure investigation by SEM and TEM revealed the correlation of the pore structure and the necking strength with the sintering profiles that determine the coalescence features of the nanoparticles. The partially sintered porous HAp microspheres containing more than 50% porosity consisting of pores and grains both in nano-scale are active in inducing the precipitation of HAp in simulated body fluid. The nano-porous HAp microspheres with an extensive surface and interconnecting pores thus demonstrate the potential of stimulating the formation of collagen and bone and the integration with the newly formed bones during physiological bone remodeling.
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| 8. |
- Liu, Zheng, et al.
(författare)
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A review of fine structures of nanoporous materials as evidenced by microscopic methods
- 2013
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Ingår i: Microscopy. - : Oxford University Press (OUP). - 2050-5698 .- 2050-5701. ; 62:1, s. 109-146
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Forskningsöversikt (refereegranskat)abstract
- This paper reviews diverse capabilities offered by modern electron microscopy techniques in studying fine structures of nanoporous crystals such as zeolites, silica mesoporous crystals, metal organic frameworks and yolk-shell materials. For the case of silica mesoporous crystals, new approaches that have been developed recently to determine the three-dimensionally periodic average structure, e. g., through self-consistent analysis of electron microscope images or through consideration of accidental extinctions, are presented. Various structural deviations in nanoporous materials from their average structures including intergrowth, surface termination, incommensurate modulation, quasicrystal and defects are demonstrated. Ibidem observations of the scanning electron microscope and atomic force microscope give information about the zeolite-crystal-growth mechanism, and an energy for unstitching a building-unit from a crystal surface is directly observed by an anatomic force microscope. It is argued how these observations lead to a deeper understanding of the materials.
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| 9. |
- Miyasaka, Keiichi, et al.
(författare)
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The role of curvature in silica mesoporous crystals
- 2012
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Ingår i: Interface Focus. - : The Royal Society. - 2042-8898 .- 2042-8901. ; 2:5, s. 634-644
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Tidskriftsartikel (refereegranskat)abstract
- Silica mesoporous crystals (SMCs) offer a unique opportunity to study micellar mesophases. Replication of non-equilibrium mesophases into porous silica structures allows the characterization of surfactant phases under a variety of chemical and physical perturbations, through methods not typically accessible to liquid crystal chemists. A poignant example is the use of electron microscopy and crystallography, as discussed herein, for the purpose of determining the fundamental role of amphiphile curvature, namely mean curvature and Gaussian curvature, which have been extensively studied in various fields such as polymer, liquid crystal, biological membrane, etc. The present work aims to highlight some current studies devoted to the interface curvature on SMCs, in which electron microscopy and electron crystallography (EC) are used to understand the geometry of silica wall surface in bicontinuous and cage-type mesostructures through the investigation of electrostatic potential maps. Additionally, we show that by altering the synthesis conditions during the preparation of SMCs, it is possible to isolate particles during micellar mesophase transformations in the cubic bicontinuous system, allowing us to view and study epitaxial relations under the specific synthesis conditions. By studying the relationship between mesoporous structure, interface curvature and micellar mesophases using electron microscopy and EC, we hope to bring new insights into the formation mechanism of these unique materials but also contribute a new way of understanding periodic liquid crystal systems.
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| 10. |
- Qian, Bin, et al.
(författare)
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Assembled nano-structures from micron-sized precursors
- 2014
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:58, s. 30754-30757
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Tidskriftsartikel (refereegranskat)abstract
- Oriented assembly of small crystals to form larger structures are common in nature and full understanding and control of such process would be beneficial for the forthcoming nano-technologies. Such bottom-up assembly of nano-structures most often requires a precursor of nano-sized crystals. Here we demonstrate a novel laser sintering process that can rupture a submicron-sized zirconia precursor into nano-sized crystals, followed by a rapid oriented assembly of these small crystals. A detailed structure study has been carried out to understand the complex process and a model has been proposed. Such a process sheds light on a new way of fabricating nano-materials using commercialized oxide materials.
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