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排序方式: 共有2141条查询结果,搜索用时 93 毫秒
941.
Liangwei Yang Zhenyu Li Linwei He Jiayu Sun Junren Wang Yumin Wang Dr. Ming Li Zibin Zhu Prof. Xing Dai Prof. Shu-Xian Hu Dr. Fuwan Zhai Qian Yang Ye Tao Prof. Zhifang Chai Prof. Shuao Wang Prof. Yaxing Wang 《Angewandte Chemie (International ed. in English)》2023,62(33):e202306465
The development of high-performance X-ray detectors requires scintillators with fast decay time, high light yield, stability, and X-ray absorption capacity, which are difficult to achieve in a single material. Here, we present the first example of a lanthanide chalcogenide of LaCsSiS4 : 1 % Ce3+ that simultaneously integrates multiple desirable properties for an ideal scintillator. LaCsSiS4 : 1 % Ce3+ demonstrates a remarkably low detection limit of 43.13 nGyair s−1 and a high photoluminescence quantum yield of 98.24 %, resulting in a high light yield of 50480±1441 photons/MeV. Notably, LaCsSiS4 : 1 % Ce3+ exhibits a fast decay time of only 29.35±0.16 ns, making it one of the fastest scintillators among all lanthanide-based inorganic scintillators. Furthermore, this material shows robust radiation and moisture resistance, endowing it with suitability for chemical processing under solution conditions. To demonstrate the X-ray imaging capacity of LaCsSiS4 : 1 % Ce3+, we fabricated a flexible X-ray detector that achieved a high spatial resolution of 8.2 lp mm−1. This work highlights the potential of lanthanide chalcogenide as a promising candidate for high-performance scintillators. 相似文献
942.
Hai-Jun Liu Shuo Zhang Prof. Yong-Ming Chai Prof. Bin Dong 《Angewandte Chemie (International ed. in English)》2023,62(48):e202313845
Highly efficient hydrogen evolution reaction (HER) electrocatalyst will determine the mass distributions of hydrogen-powered clean technologies, while still faces grand challenges. In this work, a synergistic ligand modulation plus Co doping strategy is applied to 1T−MoS2 catalyst via CoMo-metal-organic frameworks precursors, boosting the HER catalytic activity and durability of 1T−MoS2. Confirmed by Cs corrected transmission electron microscope and X-ray absorption spectroscopy, the polydentate 1,2-bis(4-pyridyl)ethane ligand can stably link with two-dimensional 1T−MoS2 layers through cobalt sites to expand interlayer spacing of MoS2 (Co−1T−MoS2-bpe), which promotes active site exposure, accelerates water dissociation, and optimizes the adsorption and desorption of H in alkaline HER processes. Theoretical calculations indicate the promotions in the electronic structure of 1T−MoS2 originate in the formation of three-dimensional metal-organic constructs by linking π-conjugated ligand, which weakens the hybridization between Mo-3d and S-2p orbitals, and in turn makes S-2p orbital more suitable for hybridization with H-1s orbital. Therefore, Co−1T−MoS2-bpe exhibits excellent stability and exceedingly low overpotential for alkaline HER (118 mV at 10 mA cm−2). In addition, integrated into an anion-exchange membrane water electrolyzer, Co−1T−MoS2-bpe is much superior to the Pt/C catalyst at the large current densities. This study provides a feasible ligand modulation strategy for designs of two-dimensional catalysts. 相似文献
943.
Jin-Dong Wang Dr. Kong-Qiu Hu Dr. Zhi-Wei Huang Prof. Lei Mei Dr. Ji-Pan Yu Prof. Zhi-Fang Chai Dr. Xin-Peng Wang Prof. Wei-Qun Shi 《欧洲无机化学杂志》2023,26(15):e202300072
The polynuclear metal clusters continually attract wide interest due to their intriguing structures and potential applications in various scientific fields. Here, four actinide clusters have been synthesized by the utilization of multifunctional ligand ferrocenecarboxylic acid (HFcc) and Th4+/U4+ ions by solvent evaporation or solvothermal synthesis strategies in different solvents. Therein, compounds 1 , 2 and 4 feature similar [An6(μ3-O)4(μ3-OH)4]12+ cores, which are further coordinated by 12 Fcc− ligands and different solvent molecules. The U6Fe12 cluster of compound 4 is linked by four free HFcc molecules via multiple hydrogen bonding to form a supramolecular cluster [U6(μ3-O)4(μ3-OH)4(Fcc)12(H2O)4] ⋅ 4HFcc. The cluster core of compound 3 is a μ3-O2− bridged [U3(μ3-O)]10+ unit, which is further coordinated by 10 Fcc− ligands via three kinds of coordination modes. It is worth noting that multifunctional Fcc− ligand not only endows compound 1 a main redox wave at E1/2=0.720 V in CH2Cl2/DMF solution, but also enables it to exhibit aggregation-induced emission (AIE) property. 相似文献
944.
Goldberg R Chai L Perkin S Kampf N Klein J 《Physical chemistry chemical physics : PCCP》2008,10(32):4939-4945
Using a surface force balance, we have measured the normal and shear forces between mica surfaces across aqueous caesium salt solutions (CsNO(3) and CsCl) up to 100 mM concentrations. In contrast to all other alkali metal ions at these concentrations, we find no evidence of hydration repulsion between the mica surfaces on close approach: the surfaces appear to be largely neutralized by condensation of the Cs ions onto the charged lattice sites, and are attracted on approach into adhesive contact. The contact separation at adhesion indicates that the condensed Cs ions protrude by 0.3 +/- 0.2 nm from each surface, an observation supported both by the relatively weak adhesion energies between the surfaces, and the relatively weak frictional yield stress when they are made to slide past each other. These observations show directly that the hydration shells about the Cs(+) ions are removed as the ions condense into the charged surface lattice. This effect is attributed to the low energies-resulting from their large ionic radius-required for dehydration of these ions. 相似文献
945.
A facile and efficient one-pot synthesis of highly substituted thiophenes has been developed and employed for the preparation of a small focused library. Treatment of 1,3-dicarbonyl compounds 1 with CS2 in the presence of K2CO3 in DMF at room temperature, followed by stepwise addition of alkyl bromides 2 and methylene active bromides 3, provided via intramolecular cyclization 2,3,4,5-tetrasubstituted thiophenes 4 in yields of 77-94%. This protocol, combining construction and modification of the thiophene ring, increases the structural diversity of final products from readily available materials. A mechanism for the one-pot synthesis of thiophenes of type 4 has been proposed. A small focused library of thiophenes is prepared using the sequential addition of reagents to achieve unique substitution in the 2 and 5 position of the thiophene ring. 相似文献
946.
A microwave-assisted protocol was developed for the construction of di- and monosubstituted 2-aminoimidazoles. The two-step reaction involves the synthesis of N-(1H-imidazol-2-yl)acetamides from readily available alpha-haloketones and N-acetylguanidine, followed by deacetylation. Significant rate enhancement was observed for both steps of the protocol, and the overall reaction time was shortened to 20 min compared to 48 h of the conventional procedures. A representative set of di- and monosubstituted 2-aminoimidazoles was prepared using commercially available parallel reactors. 相似文献
947.
A novel double-hydrophilic block copolymer (DHBC) poly(vinyl pyrrolidone)–block–poly(methacrylic acid) (PVP-b-PMAA) was synthesized via reversible addition–fragmentation chain transfer polymerization. The structure of the resulting
copolymer was characterized by 1H nuclear magnetic resonance, and the molecular weight of the block copolymer was determined by gel permeation chromatography.
The study of morphological control of calcium carbonate (CaCO3) has been performed in the presence of the PVP-b-PMAA block copolymer. Various morphologies of CaCO3 particles such as rhombohedral, multilayered, and aggregated with cavities can be produced by varying the copolymer concentrations.
The all-obtained CaCO3 particles were calcite, which was confirmed by either X-ray diffraction or Fourier transform infrared spectra. Such calcium
carbonate/polymer hybrids with complex morphologies may find valuable applications in biomimic mineralization. 相似文献
948.
Chengkuan Qin Jinling Chai Jingfei Chen Yan Xia Xiaoying Yu Jing Liu 《Colloid and polymer science》2008,286(5):579-586
The phase behavior and the solubilization of the microemulsion systems surfactant-like ionic liquids 1-hexadecyl-3-methylimidazolium
bromide (C16mimBr), 1-tetradecyl-3-methylimidazolium bromide (C14mimBr), or 1-dodecyl-3-methylimidazolium bromide (C12mimBr)/alcohol/alkane/brine have been studied with ɛ–β-fish-like phase diagram method at 40 °C and an oil-to-water mass ratio of 1:1. From the ɛ–β-fish-like phase diagram, the physicochemical parameters, such as the mass fraction of alcohol in the hydrophile–lipophile-balanced
interfacial layer (A
S), and the solubilities of ionic liquid (S
O) and alcohol (A
O) in alkane phase, were calculated. The solubilization of the microemulsion system has been discussed based on the ɛ–β-fish-like phase diagram. The smaller the oil molecule, the longer the alcohol chain length, and the larger the NaCl concentration
in water, the larger the solubilization of the microemulsion system. In this paper, the solubilization of the microemulsion
stabilized by both C12mimBr and sodium dodecyl sulfonate (sodium dodecyl sulfate) was also investigated with the ɛ–β-fish-like phase diagram. The unequimolar composite of anionic and cationic surfactants can avoid the sedimentation aroused
by the strong electrostatic attraction, and an obvious synergism effect in solubilization was obtained. 相似文献
949.
Selective adsorption of poly(ethylene oxide) onto a charged surface mediated by alkali metal ions 总被引:1,自引:0,他引:1
Chai L Goldberg R Kampf N Klein J 《Langmuir : the ACS journal of surfaces and colloids》2008,24(4):1570-1576
Using a surface force balance, we have measured normal and shear interactions between mica surfaces across pure water and across 0.1 M aqueous solutions of LiNO3, NaNO3, KNO3, and CsNO3, both prior to adding polymer and following addition of 1.5 x 10(-4) w/w poly(ethylene oxide) (PEO, Mw = 170 kD) and overnight incubation. Our results reveal that while the PEO adsorbs strongly from the KNO3 and CsNO3 solutions, unexpectedly it does not adsorb at all from the LiNO3 and NaNO3 salt solutions. We attribute this to the different nature of the hydration layers about the alkali metal ions: these favor liganding to the negatively charged mica surface of the etheric -O- group on the ethylene oxide monomer for the case of the more weakly hydrated K+ and Cs+, but not for the case of Na+ or Li+ with their more strongly bound water. A simple model relating the electrostatic energy changes occurring upon such liganding to the experimentally measured hydration energies of the different alkali metal ions supports this attribution. 相似文献
950.
Zhao Q Zheng J Chai B Pollack GH 《Langmuir : the ACS journal of surfaces and colloids》2008,24(5):1750-1755
Colloidal crystals were formed from microsphere suspensions via a simple and novel approach using gel beads. The microspheres self-assembled not only around each bead but also between beads in an ordered pattern. The crystals shrunk under incident light, with the effect of blue (wavelength 450 to 500 nm) being the most profound. The results shed new light on the fundamental issue of self-assembly and colloid science. 相似文献