Mesoporous silica hybridized by ordered mesoporous carbon for in‐tube solid‐phase microextraction

To enhance the extraction performance, a mesoporous silica was modified with ordered mesoporous carbon for solid‐phase microextraction. Three stainless‐steel wires coated with the mesoporous material were placed in a polyetheretherketone tube for getting an extraction tube. The tube was coupled to high‐performance liquid chromatography with diode array detector, and the online analysis system was constructed. Then its extraction performance was evaluated using hydrophobic polycyclic aromatic hydrocarbons, phthalates, and hydrophilic neonicotinoids. The best selectivity was presented for polycyclic aromatic hydrocarbons. Several main conditions were optimized such as sampling volume, sampling rate, methanol concentration in the sample, and desorption time, a rapid and sensitive analytical method was established toward polycyclic aromatic hydrocarbons. The analytical method exhibited wide linear range from 0.017 to 15 µg/L with acceptable correlation coefficients more than 0.9990, limits of detection in 0.005‐0.020 µg/L, limits of quantification ranging from 0.017 to 0.066 µg/L as well as large enrichment factors of 377‐2314. It was successfully applied to detect trace polycyclic aromatic hydrocarbons in some real water samples including tap water, snow water, and domestic sewage.     

Liquid chromatographic separation of alkaloids in herbal medicines: Current status and perspectives

Alkaloids are a widespread group of basic compounds in herbal medicines and have attracted great interest due to various pharmaceutical activities and desirable druggability. Their distinctive structures make chromatographic separation fairly difficult. Peak tailing, poor resolution, and inferior column‐to‐column reproducibility are common obstacles to overcome. In order to provide a valuable reference, the methodologies and/or strategies on liquid chromatographic separation of alkaloids in herbal medicines proposed from 2012 to 2019 are thoroughly summarized.     

囊泡型荧光纳米界面的构建及其对CD44蛋白的比例型传感

本文设计合成了两亲性Eu(Ⅲ)配合物(Eu L^3+)、两亲性香豆素衍生物(CA)以及荧光素修饰的透明质酸(HA-FA).Eu L^3+和CA可在水中共组装形成带正电荷的囊泡型荧光纳米界面(Eu L^3+/CA).HA-FA可通过静电引力络合在Eu L^3+/CA表面,促使CA与FA之间发生有效的荧光共振能量转移,体系的荧光发射以荧光素的绿色荧光为主.当肿瘤细胞标识物CD44蛋白与络合在囊泡表面上的透明质酸发生特异相互作用后,降低了CA与FA之间的能量转移效率,体系的荧光发射从绿色转变为蓝色.据此,实现了对CD44的高灵敏检测(DL=1.79×10^-7g/m L),而所测试的氨基酸、蛋白质等生物分子几乎不对荧光纳米界面的荧光性质产生影响.基于此,我们成功地将Eu L^3+/CA/HA-FA用于人乳腺癌细胞MCF-7和MDA-MB-231悬浮液中CD44蛋白的高效检测,该工作为构建新型CD44蛋白荧光探针提供了思路,为癌症早期诊断和治疗奠定了基础.     

Through-space charge transfer blue polymers containing acridan donor and oxygen-bridged triphenylboron acceptor for highly efficient solution-processed organic light-emitting diodes

Three kinds of through-space charge transfer(TSCT) blue polymers containing non-conjugated polystyrene backbone together with spatially-separated acridan donor and oxygen-bridged triphenylboron acceptors having different substituents of tert-butyl,hydrogen and fluorine are designed and synthesized. The designed TSCT blue polymers possess photoluminescence quantum yields up to 70% in solid-state film, single-triplet energy splitting below 0.1 eV, and typical thermally activated delayed fluorescence(TADF) effect. Meanwhile, the resulting polymers exhibit aggregation-induced emission(AIE) effect with emission intensity increased by up to ～27 folds from solution to aggregation state. By changing the substituent of acceptors to tune the charge transfer strength, blue emission with peaks from 444 to 480 nm can be realized for the resulting polymers.Solution-processed organic light-emitting diodes based on the polymers exhibit excellent device performance with Commission Internationale de L'Eclairage(CIE) coordinates of(0.16, 0.27), together with the maximum luminous efficiency of 30.7 cd A~(-1) and maximum external quantum efficiency of 15.0%, which is the best device efficiency for blue TADF polymers.     

Selective Synthesis of Z‐Cinnamyl Ethers and Cinnamyl Alcohols through Visible Light‐Promoted Photocatalytic E to Z Isomerization

A photocatalytic E to Z isomerization of alkenes using an iridium photosensitizer under mild reaction conditions is disclosed. This method provides scalable and efficient access to Z‐cinnamyl ether and allylic alcohol derivatives in high yields with excellent stereoselectivity. Importantly, this method also provides a powerful strategy for the selective synthesis of Z‐magnolol and honokiol derivatives possessing potential biological activity.     

Zero‐Dimensional Hybrid Cd‐Based Perovskites with Broadband Bluish White‐Light Emissions

Recently, low‐dimensional organic‐inorganic hybrid metal halide perovskites acting as single‐component white‐light emitting materials have attracted extensive attention, but most studies concentrate on hybrid lead perovskites. Herein, we present two isomorphic zero‐dimensional (0D) hybrid cadmium perovskites, (HMEDA)CdX₄ (HMEDA=hexamethylenediamine, X=Cl ( 1 ), Br ( 2 )), which contain isolated [CdX₄]^2? anions separated by [HMEDA]²⁺ cations. Under UV light excitation, both compounds display broadband bluish white‐light emission (515 nm for 1 and 445 nm for 2 ) covering the entire visible light spectrum with sufficient photophysical stabilities. Remarkably, compound 2 shows a high color rendering index (CRI) of 83 enabling it as a promising candidate for single‐component WLED applications. Based on the temperature‐dependent, powder‐dependent and time‐resolved PL measurements as well as other detailed studies, the broadband light emissions are attributed to self‐trapped excitons stemming from the strong electron‐phonon coupling.     

Study on wave dispersion characteristics of piezoelectric sandwich nanoplates considering surface effects

In this study, the wave propagation properties of piezoelectric sandwich nanoplates deposited on an orthotropic viscoelastic foundation are analyzed by considering the surface effects (SEs). The nanoplates are composed of a composite layer reinforced by graphene and two piezoelectric surface layers. Utilizing the modified Halpin-Tsai model, the material parameters of composite layers are obtained. The displacement field is determined by the sinusoidal shear deformation theory (SSDT). The Euler-Lagrange equation is derived by employing Hamilton’s principle and the constitutive equations of piezoelectric layers considering the SEs. Subsequently, the nonlocal strain gradient theory (NSGT) is used to obtain the equations of motion. Next, the effects of scale parameters, graphene distribution, orthotropic viscoelastic foundation, and SEs on the propagation behavior are numerically examined. The results reveal that the wave frequency is a periodic function of the orthotropic angle. Furthermore, the wave frequency increases with the increase in the SEs.

     

Thermally induced structural transformation of polytriazoleimide to polyindoleimide

A new kind of polytriazoleimide containing bisphenyl-l,2,3-triazole（BPT） was synthesized by copper-catalyzed 1,3-dipolar cycloaddition of azides and alkynes（CuAAC） and polycondensation.The thermal stability and degradation mechanism of the polytriazoleimide were investigated.The results show that the structure of BPT in polytriazoleimide transforms to phenylindole after thermal treatment,accompanying the release of N₂.     

Shears mechanism in two-dimensional cranking relativistic mean field approach

Using the new two-dimensional cranking relativistic mean field (RMF) approach, the shears mechanism of magnetic rotation based on configuration πh121/2νh-211/2 in 142Gd is microscopically and self-consistently examined by investigating the aligning angular momenta of the valence nucleons.     

Beam dynamics studies on BEPC-Ⅱstorage rings at the commissioning stage

During the 1st and 2nd stages of the commissioning of the upgrade project of the Beijing Electron Positron Collider(BEPC Ⅱ),which started on Nov.12,2006 and Oct.24,2007,respectively,we got the luminosity one tenth of its design value,provided beams to synchrotron radiation users for about 4 months,and studied beam dynamics as well.In this paper,some beam dynamics studies on the storage rings and their preliminary results are given.