Simulation Analysis on Flow Field and Temperature Field in Mould of Special Thick Slab Caster

A three-dimensional model of the thick slab continuous casting mould of 400 × 2200 mm was established. The effects of immersion depth of nozzle and casting speed on the flow field and temperature field were investigated. The high temperature distribution in mould, the thickness of narrow face solidified shell, the impact position of stream and the free surface velocity were used as the main points of analysis. Simulation and practical water modelling both exhibited the same changing trends, namely, the flow velocity of the surface increases with the distance from nozzle. The scientific basis for optimizing the flow field and temperature field in the continuous casting of special thick slab mould was acquired through calculations

Hierarchical TiO2/C nanocomposite monoliths with a robust scaffolding architecture, mesopore-macropore network and TiO2-C heterostructure for high-performance lithium ion batteries.

Engineering hierarchical structures of electrode materials is a powerful strategy for optimizing the electrochemical performance of an anode material for lithium-ion batteries (LIBs). Herein, we report the fabrication of hierarchical TiO2/C nanocomposite monoliths by mediated mineralization and carbonization using bacterial cellulose (BC) as a scaffolding template as well as a carbon source. TiO2/C has a robust scaffolding architecture, a mesopore-macropore network and TiO2-C heterostructure. TiO2/C-500, obtained by calcination at 500 °C in nitrogen, contains an anatase TiO2-C heterostructure with a specific surface area of 66.5 m(2) g(-1). When evaluated as an anode material at 0.5 C, TiO2/C-500 exhibits a high and reversible lithium storage capacity of 188 mA h g(-1), an excellent initial capacity of 283 mA h g(-1), a long cycle life with a 94% coulombic efficiency preserved after 200 cycles, and a very low charge transfer resistance. The superior electrochemical performance of TiO2/C-500 is attributed to the synergistic effect of high electrical conductivity, anatase TiO2-C heterostructure, mesopore-macropore network and robust scaffolding architecture. The current material strategy affords a general approach for the design of complex inorganic nanocomposites with structural stability, and tunable and interconnected hierarchical porosity that may lead to the next generation of electrochemical supercapacitors with high energy efficiency and superior power density.Sincere gratitude goes to funding agencies for financially support: Y. Xu to NNSF China (2117 1067, 21373100), Jilin Provincial Talent Fund (802110000412) and Tang Aoqing Professor Fund of Jilin University (450091105161). T. Hasan to the Royal Academy of Engineering Research Fellowship. B.L. Su to the Thousand Talents Program of China (“Expert of the State” position), Clare Hall Life Membership at the Clare Hall College and the financial support of the Department of Chemistry, University of Cambridge, L.H. Chen and Y. Li to the Department of Education of Hubei Province for “Chutian Scholar” program, NNSF China (21301133), Hubei Natural Science Foundation (2014CFB1 60, 2015CFB428) and the financial support of SRF for ROCS (SEM [2015]311).This is the author accepted manuscript. The final version is available from the Royal Society of Chemistry via https://doi.org/10.1039/C5NR09149

Fast detection and structural identification of carbocations on zeolites by dynamic nuclear polarization enhanced solid-state NMR

Acidic zeolites are porous aluminosilicates used in a wide range of industrial processes such as adsorption and catalysis. The formation of carbocation intermediates plays a key role in reactivity, selectivity and deactivation in heterogeneous catalytic processes. However, the observation and determination of carbocations remain a significant challenge in heterogeneous catalysis due to the lack of selective techniques of sufficient sensitivity to detect their low concentrations. Here, we combine 13C isotopic enrichment and efficient dynamic nuclear polarization magic angle spinning nuclear magnetic resonance spectroscopy to detect carbocations in zeolites. We use two dimensional 13C–13C through-bond correlations to establish their structures and 29Si–13C through-space experiments to quantitatively probe the interaction between multiple surface sites of the zeolites and the confined hydrocarbon pool species. We show that a range of various membered ring carbocations are intermediates in the methanol to hydrocarbons reaction catalysed by different microstructural β-zeolites and highlight that different reaction routes for the formation of both targeted hydrocarbon products and coke exist. These species have strong van der Waals interaction with the zeolite framework demonstrating that their accumulation in the channels of the zeolites leads to deactivation. These results enable understanding of deactivation pathways and open up opportunities for the design of catalysts with improved performances

Unprecedented and highly stable lithium storage capacity of (001) faceted nanosheet-constructed hierarchically porous TiO2/rGO hybrid architecture for high-performance Li-ion batteries.

Active crystal facets can generate special properties for various applications. Herein, we report a (001) faceted nanosheet-constructed hierarchically porous TiO2/rGO hybrid architecture with unprecedented and highly stable lithium storage performance. Density functional theory calculations show that the (001) faceted TiO2 nanosheets enable enhanced reaction kinetics by reinforcing their contact with the electrolyte and shortening the path length of Li+ diffusion and insertion-extraction. The reduced graphene oxide (rGO) nanosheets in this TiO2/rGO hybrid largely improve charge transport, while the porous hierarchy at different length scales favors continuous electrolyte permeation and accommodates volume change. This hierarchically porous TiO2/rGO hybrid anode material demonstrates an excellent reversible capacity of 250 mAh g-1 at 1 C (1 C = 335 mA g-1) at a voltage window of 1.0-3.0 V. Even after 1000 cycles at 5 C and 500 cycles at 10 C, the anode retains exceptional and stable capacities of 176 and 160 mAh g-1, respectively. Moreover, the formed Li2Ti2O4 nanodots facilitate reversed Li+ insertion-extraction during the cycling process. The above results indicate the best performance of TiO2-based materials as anodes for lithium-ion batteries reported in the literature

Mixed halide perovskites for spectrally stable and high-efficiency blue light-emitting diodes.

Bright and efficient blue emission is key to further development of metal halide perovskite light-emitting diodes. Although modifying bromide/chloride composition is straightforward to achieve blue emission, practical implementation of this strategy has been challenging due to poor colour stability and severe photoluminescence quenching. Both detrimental effects become increasingly prominent in perovskites with the high chloride content needed to produce blue emission. Here, we solve these critical challenges in mixed halide perovskites and demonstrate spectrally stable blue perovskite light-emitting diodes over a wide range of emission wavelengths from 490 to 451 nanometres. The emission colour is directly tuned by modifying the halide composition. Particularly, our blue and deep-blue light-emitting diodes based on three-dimensional perovskites show high EQE values of 11.0% and 5.5% with emission peaks at 477 and 467 nm, respectively. These achievements are enabled by a vapour-assisted crystallization technique, which largely mitigates local compositional heterogeneity and ion migration

Chinese herb mix Tiáo-Gēng-Tāng possesses antiaging and antioxidative effects and upregulates expression of estrogen receptors alpha and beta in ovariectomized rats

<p>Abstract</p> <p>Background</p> <p>Herb mixtures are widely used as an alternative to hormonal therapy in China for treatment of the menopausal syndrome. However, composition of these herb mixtures are complex and their working mechanism is often unknown. This study investigated the effect of Tiáo-Gēng-Tāng (TG-decoction), a Chinese herbal mixture extract, in balancing female hormones, regulating expression of estrogen receptors (ERs), and preventing aging-related tissue damage.</p> <p>Methods</p> <p>Ovariectomized 5-month-old female rats were used to model menopause and treated with either TG-decoction or conjugated estrogen for 8 weeks. Estradiol (E₂), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured in serum and in the hypothalamus. Hypothalamic expression of estrogen receptor (ER) alpha and beta were studied by real-time PCR and western blotting. Total antioxidant capacity (T-AOC), oxidation indicator superoxide dismutase (SOD) activity and tissue damage parameter malondialdehyde (MDA) were measured using standard assays. Aging-related ultrastructural alterations in mitochondria were studied in all animals by transmission electron microscopy.</p> <p>Results</p> <p>TG-decoction-treatment elevated E₂and lowered FSH in serum of ovariectomized rats. The potency and efficacy of TG-decoction on the hypothalamus was generally weaker than that of conjugated estrogens. However, TG-decoction was superior in upregulating expression of ERα and β. TG-decoction increased hypothalamic SOD and T-AOC levels and decreased MDAlevels and mitochondrial damage in hypothalamic neurons.</p> <p>Conclusions</p> <p>TG-decoction balances female hormones similarly to conjugated estrogens but less effectively. However, it is superior in up regulating ERα and β and exhibits antioxidative antiaging activities. Whilst it shares similar effects with estrogen, TG-decoction also seems to have distinctive and more complex functions and activities.</p