| 281. |
- Zhao, Fang, et al.
(författare)
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TiO2 nanoparticle interactions with supported lipid membranes – an example of removal of membrane patches
- 2016
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:94, s. 91102-91110
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for different levels of model systems for effect studies of engineered nanoparticles and the development of nanoparticle structure–activity relationships in biological systems. Descriptors for nanoparticles based on their interactions in molecular model systems may become useful to predict toxicological responses of the nanoparticles in cells. Towards this end, we report on nanoparticle-induced formation of holes in supported model membranes. Specifically, TiO2 nanoparticle – lipid membrane interactions were studied under low ionic strength, basic conditions (pH 8), using different membrane compositions and several surface-sensitive analytical techniques. It was found that for mixed POPC/POPG (PG fractions ≥ 35%) membranes on silica supports, under conditions where electrostatic repulsion was expected, the addition of TiO2 nanoparticles resulted in transient interaction curves, consistent with the removal of part of the lipid membrane. The formation of holes was inferred from quartz crystal microbalance with dissipation (QCM-D) monitoring, as well as from optical measurements by reflectometry, and also verified by atomic force microscopy (AFM) imaging. The interaction between the TiO2 nanoparticles and the PG-containing membranes was dependent on the presence of Ca2+ ions. A mechanism is suggested where TiO2 nanoparticles act as scavengers of Ca2+ ions associated with the supported membrane, leading to weakening of the interaction between the membrane and the support and subsequent removal of lipid mass as TiO2 nanoparticles spontaneously leave the surface. This mechanism is consistent with the observed formation of holes in the supported lipid membranes.
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| 282. |
- Zhao, Shengzhong, et al.
(författare)
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Re-direction of smoke flow in inclined tunnel fires
- 2019
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798 .- 1878-4364. ; 86, s. 113-127
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Tidskriftsartikel (refereegranskat)abstract
- The re-direction of smoke flow in inclined tunnel fires refers to the phenomenon that the smoke flow direction suddenly changes due to the changes of thermal buoyancy or outside pressure or the activation of fans. This poses special risk for fire rescue services fighting fires in tunnels. Both small-scale tunnel fire tests (28 scenarios) and numerical simulations of full-scale tunnel fires (31 scenarios) were conducted to study this special phenomenon. A one-dimensional model was used to predict the flow velocity in the inclined tunnels, based on two different methods for calculating the mean smoke temperature (Method I and Method II, respectively). Results show that the smoke flow direction could be well predicted by the model with Method II. When the ventilation velocity is relatively large and the flow tends to be one dimensional, both methods produce similar results. Further, the influences of important factors on the re-direction of smoke flows were systematically analyzed. These factors include heat release rate, tunnel slope, tunnel length, friction factor, tunnel cross sectional area and fire source location.
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| 283. |
- Zhao, Yunlong, et al.
(författare)
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Stable Alkali Metal Ion Intercalation Compounds as Optimized Metal Oxide Nanowire Cathodes for Lithium Batteries
- 2015
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 15:3, s. 2180-2185
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Tidskriftsartikel (refereegranskat)abstract
- Intercalation of ions in electrode materials has been explored to improve the rate capability in lithium batteries and supercapacitors, due to the enhanced diffusion of Li+ or electrolyte cations. Here, we describe a synergistic effect between crystal structure and intercalated ion by experimental characterization and ab initio calculations, based on more than 20 nanomaterials: five typical cathode materials together with their alkali metal ion intercalation compounds A-M-O (A = Li, Na, K, Rb; M = V, Mo, Co, Mn, Fe-P). Our focus on nanowires is motivated by general enhancements afforded by nanoscale structures that better sustain lattice distortions associated with charge/discharge cycles. We show that preintercalation of alkali metal ions in V-O and Mo-O yields substantial improvement in the Li ion charge/discharge cycling and rate, compared to A-Co-O, A-Mn-O, and A-Fe-P-O. Diffraction and modeling studies reveal that preintercalation with K and Rb ions yields a more stable interlayer expansion, which prevents destructive collapse of layers and allow Li ions to diffuse more freely. This study demonstrates that appropriate alkali metal ion intercalation in admissible structure can overcome the limitation of cyclability as well as rate capability of cathode materials, besides, the preintercalation strategy provides an effective method to enlarge diffusion channel at the technical level, and more generally, it suggests that the optimized design of stable intercalation compounds could lead to substantial improvements for applications in energy storage.
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| 284. |
- Zhao, Z., et al.
(författare)
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Responses of the radial growth of the endangered species Keteleeria fortunei to climate change in southeastern China
- 2019
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Ingår i: Trees-Structure and Function. - : Springer Science and Business Media LLC. - 0931-1890. ; 33:4, s. 977-985
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge on the responses of endangered species to current global changes can highlight the necessity and importance of protecting these species. Tree-ring-based studies provide a longer term perspective than monitoring studies on the responses and adaptations of the growth of endangered species to climate change and forest disturbances. Therefore, this study conducted a tree-ring case study on Keteleeria fortunei, an endangered and endemic species in southern China, and presents the first tree-ring chronology of K. fortunei from 1850 to 2013 in the Fuzhou area, which is located west of the Taiwan Strait. K. fortunei trees tend to grow in moister locations in closed forests and are more sensitive to forest disturbances and sunshine than Pinus massoniana. Our study shows that missing rings are more frequent for K. fortunei than for P. massoniana in the same area, which agrees with previous findings that wedging and missing rings tend to occur in trees experiencing growth suppression in closed forests.
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| 285. |
- Zheng, Wei, et al.
(författare)
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Phthalorubines : Fused-Ring Compounds Synthesized from Phthalonitrile
- 2018
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 57:47, s. 15384-15389
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Tidskriftsartikel (refereegranskat)abstract
- A series of dibenzo[a, fll1,3,5] triazino[2,1,6-cd] pyrrolizine compounds have been synthesized from phthalonitriles by a facile intramolecular cyclization process using "half-phthalocyanine" precursors, and they were characterized by X-ray crystallography, H-1 NMR spectroscopy, UV/Vis, and theoretical calculations. These compounds have spectroscopic profiles similar to phthalocyanines and porphyrins, although their inner-core structures and coordination types are totally different. They can be regarded as a new class of aromatic fused-ring compounds. The low-energy absorption of these new fused-ring compounds are located at around 600 nm. Such a low-energy pi-pi* transition is scarce in aromatic compounds having a similar molecular size. According to the nomenclature of phthalocyanines, these types of compounds have been named phthalorubines (Prs).
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| 286. |
- Zhou, Yang, et al.
(författare)
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Benzylamine-Treated Wide-Bandgap Perovskite with High Thermal-Photostability and Photovoltaic Performance
- 2017
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Ingår i: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 7:22
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Tidskriftsartikel (refereegranskat)abstract
- Mixed iodide-bromide organolead perovskites with a bandgap of 1.70-1.80 eV have great potential to boost the efficiency of current silicon solar cells by forming a perovskite-silicon tandem structure. Yet, the stability of the perovskites under various application conditions, and in particular combined light and heat stress, is not well studied. Here, FA(0.15)Cs(0.85)Pb(I0.73Br0.27)(3), with an optical bandgap of approximate to 1.72 eV, is used as a model system to investigate the thermal-photostability of wide-bandgap mixed halide perovskites. It is found that the concerted effect of heat and light can induce both phase segregation and decomposition in a pristine perovskite film. On the other hand, through a postdeposition film treatment with benzylamine (BA) molecules, the highly defective regions (e.g., film surface and grain boundaries) of the film can be well passivated, thus preventing the progression of decomposition or phase segregation in the film. Besides the stability improvement, the BA-modified perovskite solar cells also exhibit excellent photovoltaic performance, with the champion device reaching a power conversion efficiency of 18.1%, a stabilized power output efficiency of 17.1% and an open-circuit voltage (V-oc) of 1.24 V.
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| 287. |
- Aad, G., et al.
(författare)
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- 2015
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Tidskriftsartikel (refereegranskat)
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| 288. |
- Aad, G., et al.
(författare)
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- 2015
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Tidskriftsartikel (refereegranskat)
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| 289. |
- Aad, G., et al.
(författare)
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- 2015
-
Tidskriftsartikel (refereegranskat)
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| 290. |
- Aad, G., et al.
(författare)
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- 2015
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Tidskriftsartikel (refereegranskat)
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