| 1. |
- Dai, Jingjing, et al.
(författare)
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Behavior of intrinsic defects in BaF2 under uniaxial compressions : An ab initio investigation
- 2021
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Ingår i: Materials Today Communications. - : Elsevier. - 2352-4928. ; 28
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Tidskriftsartikel (refereegranskat)abstract
- We revisit the defects and related optical properties of one of the prototypical scintillator materials, BaF2, by means of density functional theory calculations. The interstitial F atom is found to be the most favorable defect to be formed, while it is rather difficult to create a F vacancy, Ba vacancy and Ba interstitial intrinsically, unless external forces are applied to the lattice, such as shock compression. The migration barriers for the above defects are remarkably path dependent. For a Ba vacancy, the migration barrier in the (001) (loading) direction is significantly reduced compared to those in the perpendicular (100) and (010) directions, while the migration along the (101) direction has the least value, which is surprisingly smaller than that at ambient pressure. An interstitial Ba atom prefers to move along the (100) and (010) directions in a manner similar to collective diffusion. The F vacancy has the lowest energy barrier along the (001) direction, while uniaxial strain greatly hinders the diffusion of F interstitials. We also study the role of defects on the optical absorption and find that a F vacancy, and interstitial F and Ba atoms are able to introduce pronounced changes to the spectra, whereas the Ba vacancy only shows marginal effects. The favorable migration paths for the different types of defects under strain or pressure can contribute to the design of specific ionic conductor properties under extreme conditions.
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| 2. |
- Song, Gang, et al.
(författare)
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Intestinal Metabolite Compound K of Ginseng Saponin Potently Attenuates Metastatic Growth of Hepatocellular Carcinoma by Augmenting Apoptosis via a Bid-Mediated Mitochondrial Pathway
- 2010
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 58:24, s. 12753-12760
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Tidskriftsartikel (refereegranskat)abstract
- It was recently shown that compound K (CK), an intestinal bacterial metabolite of ginseng saponin, exhibits antihepatocellular carcinoma (HCC) activity, and Bid is a potential drug target for HCC therapy. This paper reports a novel mechanism of CK-induced apoptosis of HCC cells via Bid-mediated mitochondrial pathway. OK dramatically inhibited HCC cells growth in concentration- and time-dependent manners, and a high dose of OK could induce HCC cell apoptotic cell death. Furthermore, the effective dose of CK potently attenuated the subcutaneous tumor growth and spontaneous HOC metastasis in vivo. At the molecular level, immunohistochemical staining revealed that Bid expression in subcutaneous tumor and liver metastasis tissues decreased dramatically in OK-treated groups compared to untreated controls, which also implies that Bid may play a critical role in the growth and progression of HCC. Further study shows that translocation of full-length Bid to the mitochondria from nuclei during cytotoxic apoptosis was associated with the release of cytochrome c from mitochondria, indicating that full-length Bid is sufficient for the activation of mitochondrial cell death pathways in response to CK treatment in HCC cells. Taken together, the results not only reveal a Bid-mediated mitochondrial pathway in HCC cells induced by CK but also suggest that OK may become a potential cytotoxic drug targeting Bid in the prevention and treatment of HCC.
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| 3. |
- Sun, Xuan, et al.
(författare)
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Construction of Electron Transfer Network by Self-Assembly of Self-n-Doped Fullerene Ammonium Iodide
- 2016
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 28:23, s. 8726-8731
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Tidskriftsartikel (refereegranskat)abstract
- Construction of pi-conjugation network in ordered fullerenes by self-assembly remains challenging for improving their optoelectronic performance and developing advanced materials. Here, we present a layered stacking of self-n-doped fullerene ammonium iodide (PCBANI) through a delicate balance among iodide anion-C-60 pi, electrostatic, and C-60 pi-pi interactions to construct an unprecedented supra molecular system. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and computational modeling are carried out to clarify the structure. Remarkably, the formation of intermolecular iodide anion pi interactions between iodide and the surrounded fullerene cores yields an iodide-linked C-60 pi-pi two-dimensional (2-D) network. Consequently, the ordered and tightly packed fullerenes sandwiching iodide could facilitate electron transfer along the network system. Comparative devices incorporating the disordered films show dramatically decreased current densities and manifest the importance of the pi-extended network for electron transfer. This work provides a key strategy to control the packing of ordered electron-transport materials to suppress defect formation. Moreover, engineering self-assembly of self-n-doped fullerenes with novel architectures, such as nanowire, nanotube, and nanoparticle would yield new functionalities that are suitable for photovoltaic devices, nanoelectronics, etc.
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| 4. |
- An, Feng-Wei, et al.
(författare)
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Establishment of a Large Animal Model for Eustachian Tube Functional Study in Miniature Pigs
- 2019
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Ingår i: Anatomical Record Part A-discoveries in Molecular Cellular and Evolutionary Biology. - : WILEY. - 1552-4884 .- 1932-8494. ; 302:6, s. 1024-1038
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Tidskriftsartikel (refereegranskat)abstract
- This study was performed to investigate whether miniature pigs are a suitable animal model for studies of the Eustachian tube (ET). Sixteen Chinese experimental miniature pigs were used in this investigation. Ten animals were used for anatomical and morphometric analyses to obtain qualitative and quantitative information regarding the ET. Three animals were used for histological analysis to determine the fine structure of ET cross-sections. Three animals were used to investigate the feasibility of balloon dilation of the Eustachian tube (BDET). The anatomical study indicated that the pharyngeal orifice and tympanic orifice of the miniature pig ET are located at the posterior end of the nasal lateral wall and anterior wall of the middle ear cavity, respectively. The cartilaginous tube was seen to pass through the whole length of the ET, the length of the cartilaginous part of the ET and the diameter of the isthmus were similar between humans and miniature pigs. The inclination of the ET in miniature pigs was larger than that in humans. The gross histology seemed to be slightly different between miniature pig and human, but the fine structures were essentially the same in both species. BDET experiments verified that the miniature pig model is suitable as a model for clinical operations. The miniature pig ET corresponds very well to that of humans. In addition, the miniature pig ET is suitable as a model for clinical operations. Therefore, the miniature pig is a valid animal model for ET study.
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| 5. |
- Cui, Weiwei, et al.
(författare)
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TOTALLY RAMIFIED RATIONAL MAPS
- 2022
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Ingår i: Conformal Geometry and Dynamics. - : American Mathematical Society (AMS). - 1088-4173. ; 26, s. 208-234
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Tidskriftsartikel (refereegranskat)abstract
- Totally ramified rational maps and regularly ramified rational maps are defined and studied in this paper. We first give a complete classification of regularly ramified rational maps and show that our definition of a regularly ramified rational map is equivalent to a much stronger definition of a map of this kind given by Milnor [Dynamics in one complex variable, Princeton University Press, Princeton, NJ, 2006]. Then we show that (1) any totally ramified rational map of degree d ≤ 6 must be regularly ramified; (2) for any integer d > 6, there exists a totally ramified rational map of degree d which is not regularly ramified. Furthermore, we count totally ramified rational maps up to degree 10. Finally, we present explicit formulas for all totally but not regularly ramified rational maps of degree 7 or 8, up to pre and post-composition by Möbius transformations.
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| 6. |
- Du, Chun, et al.
(författare)
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9-Alkylidene-9H-Fluorene-Containing Polymer for High-Efficiency Polymer Solar Cells
- 2011
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Ingår i: Macromolecules. - : American Chemical Society. - 0024-9297 .- 1520-5835. ; 44:19, s. 7617-7624
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Tidskriftsartikel (refereegranskat)abstract
- A novel donor-acceptor copolymer containing 9-alkylidene-9H-fluorene unit in the main chain, poly[9-(1-hexylheptylidene)-2,7-fluorene-alt-5, 5-(4,7-di-2-thienyl-5,6-dialkoxy-2,1,3-benzothiadiazole)] (PAFDTBT), has been synthesized and evaluated in bulk heterojunction polymer solar cells (BHJ PSCs). The polymer possesses a low band gap of 1.84 eV, a low-lying HOMO energy level (5.32 eV), and excellent solubility in common organic solvents. PSCs based on PAFDTBT and (6,6)-phenyl-C(71)-butyric add methyl ester (PC(71)BM) demonstrate a power conversion efficiency (PCE) of 6.2% with a high fill factor (FF) of 0.70, which indicates that 9-alkylidene-9H-fluorene can be a very useful building block for constructing narrow band gap conjugated polymers for high-efficiency BHJ PSCs.
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| 7. |
- Hu, Cheng, et al.
(författare)
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On the steady-state workpiece flow mechanism and force prediction considering piled-up effect and dead metal zone formation
- 2021
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Ingår i: Journal of Manufacturing Science and Engineering. - : ASME International. - 1087-1357 .- 1528-8935. ; 143:4
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Tidskriftsartikel (refereegranskat)abstract
- The manufacturing of miniaturized components is indispensable in modern industries, where the uncut chip thickness (UCT) inevitably falls into a comparable magnitude with the tool edge radius. Under such circumstances, the ploughing phenomenon between workpiece and tool becomes predominant, followed by the notable formation of dead metal zone (DMZ) and piled-up chip. Although extensive models have been developed, the critical material flow status in such microscale is still confusing and controversial. In this study, a novel material separation model is proposed for the demonstration of workpiece flow mechanism around the tool edge radius. First, four critical positions of workpiece material separation are determined, including three points characterizing the DMZ pattern and one inside considered as stagnation point. The normal and shear stresses as well as friction factors along the entire contact region are clarified based on slip-line theory. It is found that the friction coefficient varies symmetrically about the stagnation point inside DMZ and remains constant for the rest. Then, an analytical force prediction model is developed with Johnson-Cook constitutive model, involving calibrated functions of chip-tool contact length and cutting temperature. The assumed tribology condition and morphologies of material separation including DMZ are clearly observed and verified through various finite element (FE) simulations. Finally, comparisons of cutting forces from cutting experiments and predicted results are adopted for the validation of the predictive model.
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| 8. |
- Lee, Ben H, et al.
(författare)
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Highly functionalized organic nitrates in the southeast United States: Contribution to secondary organic aerosol and reactive nitrogen budgets.
- 2016
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 113:6, s. 1516-21
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Tidskriftsartikel (refereegranskat)abstract
- Speciated particle-phase organic nitrates (pONs) were quantified using online chemical ionization MS during June and July of 2013 in rural Alabama as part of the Southern Oxidant and Aerosol Study. A large fraction of pONs is highly functionalized, possessing between six and eight oxygen atoms within each carbon number group, and is not the common first generation alkyl nitrates previously reported. Using calibrations for isoprene hydroxynitrates and the measured molecular compositions, we estimate that pONs account for 3% and 8% of total submicrometer organic aerosol mass, on average, during the day and night, respectively. Each of the isoprene- and monoterpenes-derived groups exhibited a strong diel trend consistent with the emission patterns of likely biogenic hydrocarbon precursors. An observationally constrained diel box model can replicate the observed pON assuming that pONs (i) are produced in the gas phase and rapidly establish gas-particle equilibrium and (ii) have a short particle-phase lifetime (∼2-4 h). Such dynamic behavior has significant implications for the production and phase partitioning of pONs, organic aerosol mass, and reactive nitrogen speciation in a forested environment.
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| 9. |
- Lee, Chunsik, et al.
(författare)
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VEGF-B prevents excessive angiogenesis by inhibiting FGF2/FGFR1 pathway
- 2023
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Ingår i: SIGNAL TRANSDUCTION AND TARGETED THERAPY. - : SPRINGERNATURE. - 2095-9907 .- 2059-3635. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Although VEGF-B was discovered as a VEGF-A homolog a long time ago, the angiogenic effect of VEGF-B remains poorly understood with limited and diverse findings from different groups. Notwithstanding, drugs that inhibit VEGF-B together with other VEGF family members are being used to treat patients with various neovascular diseases. It is therefore critical to have a better understanding of the angiogenic effect of VEGF-B and the underlying mechanisms. Using comprehensive in vitro and in vivo methods and models, we reveal here for the first time an unexpected and surprising function of VEGF-B as an endogenous inhibitor of angiogenesis by inhibiting the FGF2/FGFR1 pathway when the latter is abundantly expressed. Mechanistically, we unveil that VEGF-B binds to FGFR1, induces FGFR1/VEGFR1 complex formation, and suppresses FGF2-induced Erk activation, and inhibits FGF2-driven angiogenesis and tumor growth. Our work uncovers a previously unrecognized novel function of VEGF-B in tethering the FGF2/FGFR1 pathway. Given the anti-angiogenic nature of VEGF-B under conditions of high FGF2/FGFR1 levels, caution is warranted when modulating VEGF-B activity to treat neovascular diseases.
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| 10. |
- Qin, Tao, 1984-, et al.
(författare)
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A novel rapid synthesis, characterization and applications of calcium phosphate nanospheres from Baltic seawater
- 2018
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Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 44:8, s. 9076-9079
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Tidskriftsartikel (refereegranskat)abstract
- Due to the considerable high bio-compatibility, calcium phosphate nanoparticles are widely used in biomedical applications. This study proposes a novel strategy for low-cost manufacturing calcium phosphate nanoporous spheres. The controlled reaction only took less than five minutes, when using Baltic seawater with the dissolved calcium concentration of 2.2 mM as the calcium resources. Porous nanospheres were obtained, with spheres ranging from 50 to 130 nm. The obtained nanospheres possess high drug-loading capacity and exhibit sustained release and pH-dependent properties. In addition, this method provides a general efficient strategy to synthesize other low-cost inorganic nanospheres from seawater.
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