Focusing the electromagnetic wave with a magnetic field

We examine manipulating the electromagnetic (EM) wave with an external static magnetic field (ESMF) taking advantage of the versatility of the magnetic photonic crystal (PC). The effect of a nonuniform ESMF on the permeability of the constituent magnetic material in the PC is demonstrated to create a gradient of the effective optical index in the crystal, leading to the focusing of the EM wave, with a magnetically tunable focal length, focused waist radius, and the intensity at the focus.     

Comprehensive two-dimensional separations based on capillary high-performance liquid chromatography and microchip electrophoresis

A novel comprehensive two-dimensional (2-D) separation system coupling capillary high-performance liquid chromatography (cHPLC) with microchip electrophoresis (chip CE) is demonstrated. Reversed-phase cHPLC was used as the first dimension, and chip CE acted as the second dimension to perform fast sample transfers and separations. A valve-free gating interface was devised simply by inserting the outlet-end of LC column into the cross-channel on a specially designed chip. A home-made confocal laser-induced fluorescence detector was used to perform on-chip high-sensitive detection. The cHPLC effluents were continuously delivered to the chip and pinched injections of the effluents every 20 seconds were employed for chip CE separation. Gradient elution of cHPLC was carried out to obtain the high-efficiency separation. Free-zone electrophoresis was performed with triethylamine buffer to achieve high-speed separation and prevent sample adsorption. Such a simple-made comprehensive system was proved to be effective. The relative standard deviations for migration time and peak height of rhodamine B in 150 sample transfers were 3.2% and 9.8%, respectively. Peptides of the fluorescein isothiocyanate (FITC)-labeled tryptic digests of bovine serum albumin were fairly resolved and detected with this comprehensive 2-D system.     

Bifunctional Catalysts Containing Zn(II) and Imidazolium Salt Ionic Liquids for Chemical Fixation of Carbon Dioxide

Zn(II) can efficiently promote the catalytic performance of imidazolium salt ionic liquids (imi-ILs) for the chemical fixation of CO₂ into epoxides. To obtain sustainability, immobilized bifunctional catalysts containing both imi-ILs and Zn(II) were prepared using bimodal mesoporous silica (BMMs) as carrier, through grafting of Zn(OAc)₂ and 1-(trimethoxysilyl)propyl-3-methylimidazolium chloride (Si-imi) separately in the nanopores. The catalysts, named as BMMs−Zn&ILs, were identified as efficient catalysts for cycloaddition reaction of CO₂ into epoxides under solvent-free conditions. BMMs−Zn&ILs showed good catalytic activity, which increased with the increase of the molar ratio of Zn(II) to Si-imi. As a comparison, different catalytic systems including homogeneous imi-IL, BMMs-ILs and BMMs−Zn were studied to demonstrate different cooperation behaviors. Furthermore, the kinetics studies of homogeneous and heterogeneous bifunctional catalysts were employed to confirm the differences, as well as to support the proposed cooperative catalysis mechanism in the nanopores.     

Hyperfluorescent polymers enabled by through-space charge transfer polystyrene sensitizers for high-efficiency and full-color electroluminescence

Fluorescent polymers are suffering from low electroluminescence efficiency because triplet excitons formed by electrical excitation are wasted through nonradiative pathways. Here we demonstrate the design of hyperfluorescent polymers by employing through-space charge transfer (TSCT) polystyrenes as sensitizers for triplet exciton utilization and classic fluorescent chromophores as emitters for light emission. The TSCT polystyrene sensitizers not only have high reverse intersystem crossing rates for rapid conversion of triplet excitons into singlet ones, but also possess tunable emission bands to overlap the absorption spectra of fluorescent emitters with different bandgaps, allowing efficient energy transfer from the sensitizers to emitters. The resultant hyperfluorescent polymers exhibit full-color electroluminescence with peaks expanding from 466 to 640 nm, and maximum external quantum efficiencies of 10.3–19.2%, much higher than those of control fluorescent polymers (2.0–3.6%). These findings shed light on the potential of hyperfluorescent polymers in developing high-efficiency solution-processed organic light-emitting diodes and provide new insights to overcome the electroluminescence efficiency limitation for fluorescent polymers.

Hyperfluorescent polymers with high efficiency and full-color electroluminescence are developed by using through-space charge transfer polystyrenes as sensitizers for exciton utilization and fluorescent chromophores as emitters for light emission.     

聚合物/无机纳米粒子复合膜在气体分离中的研究进展

由于聚合物膜具有可高度设计、机械性能好、易于加工 等优点,是理想的气体分离材料。然而,聚合物膜在气体选择性和渗透性方面存在平衡限制,在聚合物中引入纳米粒子,是提高气体分离性能的一种有效手段。本文基于聚合物/无机纳米粒子复合膜在气体分离领域的研究现状,重点阐述了零维纳米粒子（二氧化硅、二氧化钛）、一维纳米粒子（碳纳米管）、二维纳米粒子（氧化石墨烯、二维过渡金属氧化物）、三维纳米粒子（金属有机框架、沸石）对气体分离性能的影响,并展望了聚合物复合分离膜的发展趋势,为未来高效分离膜的研发提供了参考。     

Synthesis and Electrochemical Investigation of O3-Type High-nickel NCM Cathodes for Sodium-ion Batteries

Sodium ion batteries(SIBs)are promising energy storage devices for smart grid applications due to their low cost and the high abundance of sodium,but few cathode materials of SIBs with high energy density are available for practical applications.Herein,a series of NaNCM ternary materials(NCM=nickel-cobalt-manganese)is obtained by solid-phase reaction with well-regulated temperature and other reaction conditions.XRD results show that impure NiO phase is more likely to occur under high nickel content.The cross-section SEM indicates that the primary particles in the electrode materials are radially distributed along the radial direction,and the internal porous structure is conducive to the infiltration of electrolyte.The initial specific capacities of Na[Ni0.68Co0.10Mn0.22]O2(NaNCM712),Na[Ni0.6Co0.2Mn0.2]O2(NaNCM622)and Na[Ni0.4Co0.3Mn0.3]O2(NaNCM433)at 0.2 C are 165.5,153.1 and 146.8 mA·h/g,and the corresponding capacity retention rates are 63.2%,78.5%and 71.7%after 100 cycles.NaNCM712 possesses the highest initial specific capacity,and NaNCM433 delivers the best rate capability.The rate capabilities of high-nickel and low-cobalt NaNCM cathodes need to be further improved.Moreover,ex-situ XRD pattern reveals the structure evolution(from O3 type to P2 type)during a long cycling charge and discharge process.     

Alkoxy encapsulation of carbazole-based thermally activated delayed fluorescent dendrimers for highly efficient solution-processed organic light-emitting diodes

Two n-butoxy-encapsulated dendritic thermally activated delayed fluorescent(TADF) emitters(namely O-D1 and O-D2) with the first-/second-generation carbazoledendrons are designed and synthesized via C—N coupling between carbazoledendrons and 2,4,6-tris(4-bromophenyl)-1,3,5-triazine core.It is found that,compa red with the commo nly-used tert-butyl groups,the use of n-butoxy encapsulation groups can lead to smallersinglet-triplet energy gap for the dendrimers,producing stronger TADF effect together with faster reverse intersystem crossing process.Solution-processed TADF organic light-emitting diodes(OLEDs) utilizingalkoxy-encapsulated dendrimers O-D1 and O-D2 as emitters exhibitstate-of-the-art device efficiency withthe maximum external quantum efficiency up to 16.8% and 20.6%,respectively,which are ～1.6 and～2.0 times that of the tert-butyl-encapsulated counterparts.These results suggest that alkoxy encapsulation of the carbazole-based TADF dendrimers can be a promising approach for developing highly efficient emitters for solution-processed OLEDs.     

Procyanidins and Their Therapeutic Potential against Oral Diseases

Procyanidins, as a kind of dietary flavonoid, have excellent pharmacological properties, such as antioxidant, antibacterial, anti-inflammatory and anti-tumor properties, and so they can be used to treat various diseases, including Alzheimer’s disease, diabetes, rheumatoid arthritis, tumors, and obesity. Given the low bioavailability of procyanidins, great efforts have been made in drug delivery systems to address their limited use. Nowadays, the heavy burden of oral diseases such as dental caries, periodontitis, endodontic infections, etc., and their consequences on the patients’ quality of life indicate a strong need for developing effective therapies. Recent years, plenty of efforts are being made to develop more effective treatments. Therefore, this review summarized the latest researches on versatile effects and enhanced bioavailability of procyanidins resulting from innovative drug delivery systems, particularly focused on its potential against oral diseases.     

Enabling High-Voltage Lithium Metal Batteries by Manipulating Solvation Structure in Ester Electrolyte

Lithium metal is an ideal electrode material for future rechargeable lithium metal batteries. However, the widespread deployment of metallic lithium anode is significantly hindered by its dendritic growth and low Coulombic efficiency, especially in ester solvents. Herein, by rationally manipulating the electrolyte solvation structure with a high donor number solvent, enhancement of the solubility of lithium nitrate in an ester-based electrolyte is successfully demonstrated, which enables high-voltage lithium metal batteries. Remarkably, the electrolyte with a high concentration of LiNO₃ additive presents an excellent Coulombic efficiency up to 98.8 % during stable galvanostatic lithium plating/stripping cycles. A full-cell lithium metal battery with a lithium nickel manganese cobalt oxide cathode exhibits a stable cycling performance showing limited capacity decay. This approach provides an effective electrolyte manipulation strategy to develop high-voltage lithium metal batteries.     

Acid controlled diastereoselectivity in asymmetric aldol reaction of cycloketones with aldehydes using enamine-based organocatalysts

The example of syn-aldol reaction of cyclohexanone to aldehyde was demonstrated based on chiral diamine organocatalysts and it was realized either by increasing the molecular size of acid additives or by introducing a hydrogen-bond donor into acid additives.