Enabling High-Performance All-Solid-State Batteries via Guest Wrench in Zeolite Strategy.

All-solid-state batteries with a high energy density and safety are desirable candidates for next-generation energy storage applications. However, conventional solid electrolytes for all-solid-state batteries encounter limitations such as poor ionic conduction, interfacial compatibility, instability, and high cost. Herein, taking advantage of the ingenious capability of zeolite to incorporate functional guests in its void space, we present an innovative ionic activation strategy based on the "guest wrench" mechanism, by introducing a pair of cation and anion of LiTFSI-based guest species (GS) into the supercage of the LiX zeolite, to fabricate a zeolite membrane (ZM)-based solid electrolyte (GS-ZM) with high Li ionic conduction and interfacial compatibility. The restriction of zeolite frameworks toward the framework-associated Li ions is significantly reduced through the dynamic coordination of Li ions with the "oxygen wrench" of TFSI- at room temperature as shown by experiments and Car-Parrinello molecular dynamics simulations. Consequently, the GS-ZM shows an ∼100% increase in ionic conductivity compared with ZM and an outstanding Li+ transference number of 0.97. Remarkably, leveraging the superior ionic conduction of GS-ZM with the favorable interface structure between GS-ZM and electrodes, the assembled all-solid-state Li-ion and Li-air batteries based on GS-ZM exhibit the best-level electrochemical performance much superior to batteries based on liquid electrolytes: a capacity retention of 99.3% after 800 cycles at 1 C for all-solid-state Li-ion batteries and a cycle life of 909 cycles at 500 mA g-1 for all-solid-state Li-air batteries. The mechanistic discovery of a "guest wrench" in zeolite will significantly enhance the adaptability of zeolite-based electrolytes in a variety of all-solid-state energy storage systems with high performance, high safety, and low cost.

Construction of a High Nuclear Gadolinium Cluster with Enhanced Magnetocaloric Effect through Structural Transition.

Starting from a dinuclear complex {Gd2(L)2(NO3)4(H2O)2}·2(CH3CN) (1) based on 2,6-dimethoxyphenol (HL), a nonanuclear cluster {Gd9(L)4(µ4-OH)2(µ3-OH)8(µ2-OCH3)4(NO3)8 (H2O)8}(OH)·2H2O (2) was obtained via modulating the amount of the ligand and base. Both of them have been structurally and magnetically characterized. Complex 1 decorates the Gd2 core bridged by double µ2-phenoxyl oxygen atoms and coordinated neutral CH3CN molecules, while 2 features the Gd9 core with a sandglass-like topology. Magnetic investigations reveal that the weaker antiferromagnetic interactions between adjacent metal ions exist in complex 2 than in 1, which is in agreement with the theoretical results. Meanwhile, the magnetocaloric effect with a maximum -ΔS m value changes from 27.32 to 40.60 J kg-1 K-1 at 2 K and 7 T.

Er:YAG MOPA system based on a polarization-multiplexing 4-pass structure.

A 4-pass structure Er:YAG MOPA system at 1645 nm is theoretically and experimentally investigated. In accordance with the theoretical analysis, the 4-pass structure significantly improved the amplification performance. The highest gain is about 4 with 1 mJ incident seed energy. The power fluctuation and beam quality are improved after the amplification.

Neglect and associated factors among migrant middle school students in Tianjin / 中国学校卫生

Objective@#To understand neglect and its associated factors among migrant middle school students in Tianjin, and to help them develop physically and mentally.@*Methods@#A survey of 3 666 middle school students in 10 middle schools located in migrant gathering regions was conducted. Neglect and associated factors were collected and compared between migrant and non-migrant students.@*Results@#The neglect rate of migrant middle school students in Tianjin was 45.79% and that of non-migrant students was 31.37%, the difference was statistically significant (χ2=56.25, P<0.01). The total neglect of middle school students who moved with them was (52.46±8.12) points; the neglect of boys, junior high schools, non-only children, fathers and mothers with high school education and below were significantly higher than those of girls, high schools, single children, and parents with high school education (t=3.73, 10.40, -11.36, 13.81, 15.57, P<0.01). The longer the follow-up period and the lower the family income, the higher the degree of neglect among the middle school students, and the difference was statistically significant (F=89.27, 53.48, P<0.01). Regression analysis showed that the following time (OR=3.55), whether the only child (OR=4.19) showed a positive correlation with the neglect of middle school students; family income (OR=0.71), parental education (OR=0.48, 0.25) were negatively correleted with neglect (P<0.05).@*Conclusion@#The neglect of middle school students in Tianjin is serious. The time of family migration, family income and parental education are important factors affecting neglect.

High-energy, single-frequency, Q-switched Er:YAG laser with a double-crystals-end-pumping architecture.

A high-energy, single-frequency, injection-seeded, Q-switched Er:YAG laser oscillating at 1645 nm is demonstrated. For obtaining high output energy, a double-crystals-end-pumping architecture is utilized. The maximum output energies of single-frequency pulses are 12.84 mJ, 16.87 mJ, and 20.3 mJ at pulse repetition rates of 500 Hz, 300 Hz and 200 Hz, respectively. Correspondingly, the pulse widths are 162 ns, 125 ns, and 110 ns, respectively. The half-width of the pulse spectrum at the pulse repetition rate of 200 Hz is 4.59 MHz, measured by using the heterodyne technique, which is 1.14 times transform limited. To the best of our knowledge, 20.3 mJ is the highest energy obtained from a single-frequency, injection-seeded Er:YAG laser.

Photoluminescence from quasi-type-II spherical CdSe-CdS core-shell quantum dots.

Spherical CdSe-CdS core-shell quantum dots (QDs) are found to be flexible in the transition between the type-I regime and the type-II regime with different core/shell dimensions. The quasi-type-II feature of the colloidal dots is confirmed with time-resolved photoluminescence (PL) measurements. Two recombination paths of the excitons with significantly different decay rates are observed and analyzed. The spherical CdSe-CdS core-shell QDs are numerically simulated to investigate the carrier separation. A relatively long radiative lifetime and high degree of spatial carrier separation provide good potential to achieve lasing under continuous-wave excitation. Amplified spontaneous emission at room temperature is detected from the QDs embedded in the polymer matrix. It is shown that a larger shell thickness results in a lower pumping threshold, while a smaller shell thickness leads to higher PL efficiency.

Pharmacokinetics and urine metabolite identification of dehydroevodiamine in the rat.

This study investigates the oral bioavailability and characterizes urine metabolites of dehydroevodiamine (DeHE), one of the bioactive alkaloids isolated from the fruit of Evodia rutaecarpa . A freely moving rat model coupled with an automated blood sample system was used to evaluate the pharmacokinetics of DeHE. High-performance liquid chromatography (HPLC), mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectrometry were applied to determine DeHE and its metabolites. The averaged oral bioavailability of DeHE (100 and 500 mg/kg) in the freely moving rats was approximately 15.35%. Cumulative fecal and urinary excretions of unchanged DeHE were 6 and 0.5%, respectively, after a single oral dose (500 mg/kg) of DeHE. The protein binding of DeHE in rat plasma was 65.6 ± 6.5%. Six metabolites, including five DeHE-O-glucuronides and one DeHE-sulfate, were identified after oral administration. The structures of two glucuronide conjugates, DeHE-10-O-glucuronide (M3) and DeHE-11-O-glucuronide (M4), and one sulfate conjugate, DeHE-12-sulfate (M6), were assigned. The findings indicate that the oral bioavailability of DeHE was much higher than that of evodiamine, and hydroxylation and conjugative metabolism were essential for the urinary elimination of DeHE.

Synthesis of tetrahedral quasi-type-II CdSe-CdS core-shell quantum dots.

Synthesis of colloidal nanocrystals of II-VI semiconductor materials has been refined in recent decades and their size dependent optoelectronic properties have been well established. Here we report a facile synthesis of CdSe-CdS core-shell heterostructures using a two-step hot injection process. Red-shifts in absorption and photoluminescence spectra show that the obtained quantum dots have quasi-type-II alignment of energy levels. The obtained nanocrystals have a heterostructure with a large and highly faceted tetrahedral CdS shell grown epitaxially over a spherical CdSe core. The obtained morphology as well as high resolution electron microscopy confirms that the tetrahedral shell have a zinc blende crystal structure. A phenomenological mechanism for the growth and morphology of the nanocrystals is discussed.

Novel solution route synthesis of low thermal conductivity nanocrystalline bismuth telluride.

A novel synthesis approach based on a solution route has been developed for the fabrication of nanocrystalline bismuth telluride. The method consists of dissolving both bismuth and tellurium into the same organic solvent with the assistance of complexing agents and one-step coprecipitation of bismuth telluride. The synthesized nanocrystalline bismuth telluride powders possess rhombohedral crystal structure and are nanosheet/nanorod-like with an average size of between 30 and 40 nm. The thermal conductivity of the hot-pressed compact consolidated from the as-synthesized nanopowders is 0.39-0.45 Wm(-1)K(-1) in the temperature range of 323 to 523 K, which is at most one third of that of bulk bismuth telluride-based materials reported in the literature. Such low thermal conductivity of the investigated bismuth telluride is mainly attributed to substantially high concentration of grain boundaries provided by nanostructuring to scatter phonons intensively.

Nanocomposites of polymer and inorganic nanoparticles for optical and magnetic applications.

This article provides an up-to-date review on nanocomposites composed of inorganic nanoparticles and the polymer matrix for optical and magnetic applications. Optical or magnetic characteristics can change upon the decrease of particle sizes to very small dimensions, which are, in general, of major interest in the area of nanocomposite materials. The use of inorganic nanoparticles into the polymer matrix can provide high-performance novel materials that find applications in many industrial fields. With this respect, frequently considered features are optical properties such as light absorption (UV and color), and the extent of light scattering or, in the case of metal particles, photoluminescence, dichroism, and so on, and magnetic properties such as superparamagnetism, electromagnetic wave absorption, and electromagnetic interference shielding. A general introduction, definition, and historical development of polymer-inorganic nanocomposites as well as a comprehensive review of synthetic techniques for polymer-inorganic nanocomposites will be given. Future possibilities for the development of nanocomposites for optical and magnetic applications are also introduced. It is expected that the use of new functional inorganic nano-fillers will lead to new polymer-inorganic nanocomposites with unique combinations of material properties. By careful selection of synthetic techniques and understanding/exploiting the unique physics of the polymeric nanocomposites in such materials, novel functional polymer-inorganic nanocomposites can be designed and fabricated for new interesting applications such as optoelectronic and magneto-optic applications.

Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites.

PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

Template electrodeposition of ordered bismuth telluride nanowire arrays.

Thermoelectric bismuth telluride nanowire arrays have been synthesized by direct-current electrode-position into porous anodic alumina membranes both galvanostatically and potentiostatically. The as-synthesized Bi2Te3 nanowire arrays are highly ordered in large area, stoichiometric, uniform, with high aspect ratio (above 100) and high filling ratio (>90%) of the membrane. The effects of different electrochemical deposition parameters on crystal structures, morphology and composition have been investigated. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) have been used to characterize the physical and chemical properties of the nanowires.