Fabrication of ZnSe/C Hollow Polyhedrons for Lithium Storage

ZnSe has got extensive attention for high-performance LIBs anode due to its remarkable theoretical capacity and environmental friendliness. Nevertheless, the large volume variation for the ZnSe in the discharge/charge processes brings about rapid capacity fading and poor rate performance. Herein, ZnSe/C hollow polyhedrons are successfully synthesized by selenization of zeolitic imidazolate framework-8 (ZIF-8) with resorcinol-formaldehyde (RF) coating. The protection of C layer derived from RF coating layer and Ostwald ripening during the process of selenization play important roles in promoting formation of ZnSe/C hollow polyhedrons. The ZnSe/C hollow polyhedrons exhibit good rate performance and long-term cycle stability (345 mAh g⁻¹ up to 1000 cycles at 1 A g⁻¹) for lithium ion batteries (LIBs) anode. The improved electrochemical performance is benefit from the unique ZnSe/C hollow structure, in which the hollow structure can effectively avoid terrible volume expansion, and the thin ZnSe/C shell can not only provide adequate diffusion paths of lithium ions and but also enhance the electronic conductivity.     

A controlled porosity osmotic pump system with biphasic release of theophylline

A controlled porosity osmotic pump system with biphasic release of theophylline was developed for the nocturnal therapy of asthma. The developed system was composed of a tablet-in-tablet (TNT) core and a controlled porosity coating membrane. Release pattern of the developed system was influenced by amount of pore former (18.2-45.5%, w/w of polymer), weight gain (16-26 mg per tablet) of the coating membrane and osmotic agents used in inner layer of the TNT core. When sodium phosphate and sodium chloride were selected as the osmotic agents in inner and outer layer of the TNT core respectively, target release profile was obtained with coating solution cellulose acetate-polyethylene glycol 400-diethyl phthalate (54.5-36.4-9.1%, w/w) at a weight gain of 16-22 mg per tablet. To examine the mechanism of drug release, release profiles of osmotic agents, micro-environmental osmotic pressure and micro-environmental pH of the formulation during dissolution were studied. Micro-environmental osmotic pressure decreased and micro-environmental pH increased continuously during the whole dissolution process, theophylline release was dominated by the successive dissolution of sodium chloride and sodium phosphate. Theophylline solubility increased as environmental pH exceeded 10.8. At the last stage of the biphasic release, micro-environmental pH in the developed formulation reached 10.9, and theophylline release was promoted by its elevated solubility despite of the decrease of micro-environmental osmotic pressure in the developed formulaiton.     

Preparation and characterization of poly(propylene carbonate)/montmorillonite nanocomposites by solution intercalation

Poly(propylene carbonate) (PPC) is a new biodegradable aliphatic polycarbonate. However, the poor thermal stability and low glass transition temperatures (T_g) have limited its applications. To improve the thermal properties of PPC, organophilic montmorillonite (OMMT) was mixed with PPC by a solution intercalation method to produce nanocomposites. An intercalated-and-flocculated structure of PPC/OMMT nanocomposites was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal and mechanical properties of PPC/OMMT nanocomposites were investigated by thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC), and electronic tensile tester. Due to the nanometer-sized dispersion of layered silicate in polymer matrix, PPC/OMMT nanocomposites exhibit improved thermal and mechanical properties than pure PPC. When the OMMT content is 4 wt%, the PPC/OMMT nanocomposite shows the best thermal and mechanical properties. These results indicate that nanocomposition is an efficient and convenient method to improve the properties of PPC.     

A new anti-diabetic sesquiterpenoid from Acorus calamus

A new sesquiterpenoid,1β,5α-guaiane-4β,10α-diol-6-one(1),was isolated from 70%EtOH extract of the rhizomes of Acorus calamus.The structure was determined on spectroscopic methods,especially 2D NMR techniques.The absolute configuration of 1 was confirmed by TDDFT quantum chemical calculation of its ECD spectrum.Compound 1 showed promising anti-diabetic activity on a insulin-mediated glucose consumption model of HepG2 cells.     

The sandwich-type electrochemiluminescence immunosensor for α-fetoprotein based on enrichment by Fe3O4-Au magnetic nano probes and signal amplification by CdS-Au composite nanoparticles labeled anti-AFP

A novel and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was fabricated on a glassy carbon electrode (GCE) for ultra trace levels of α-fetoprotein (AFP) based on sandwich immunoreaction strategy by enrichment using magnetic capture probes and quantum dots coated with Au shell (CdS-Au) as the signal tag. The capture probe was prepared by immobilizing the primary antibody of AFP (Ab1) on the core/shell Fe₃O₄-Au nanoparticles, which was first employed to capture AFP antigens to form Fe₃O₄-Au/Ab1/AFP complex from the serum after incubation. The product can be separated from the background solution through the magnetic separation. Then the CdS-Au labeled secondary antibody (Ab2) as signal tag (CdS-Au/Ab2) was conjugated successfully with Fe₃O₄-Au/Ab1/AFP complex to form a sandwich-type immunocomplex (Fe₃O₄-Au/Ab1/AFP/Ab2/CdS-Au), which can be further separated by an external magnetic field and produce ECL signals at a fixed voltage. The signal was proportional to a certain concentration range of AFP for quantification. Thus, an easy-to-use immunosensor with magnetic probes and a quantum dots signal tag was obtained. The immunosensor performed at a level of high sensitivity and a broad concentration range for AFP between 0.0005 and 5.0 ng mL⁻¹ with a detection limit of 0.2 pg mL⁻¹. The use of magnetic probes was combined with pre-concentration and separation for trace levels of tumor markers in the serum. Due to the amplification of the signal tag, the immunosensor is highly sensitive, which can offer great promise for rapid, simple, selective and cost-effective detection of effective biomonitoring for clinical application.     

脑啡肽的固相合成与LC-MS/MS分离鉴定

多肽在生命过程中扮演着重要的角色,对其生理生化功能的研究与应用,离不开对单一多肽物质的需求,而化学合成法是获取目标多肽的最有效方法之一。对合成产物的分离与鉴定,是优化合成条件,以得到高产率的重要保证。以两种内源性神经肽亮氨酸脑啡肽和甲硫氨酸脑啡肽为模型,利用Fmoc固相多肽合成策略对其进行合成,并建立了HPLC-ESI-MS/MS新方法用于所制备的亮氨酸脑啡肽和甲硫氨酸脑啡肽的分离与结构鉴定。研究结果显示,主要合成产物均为目标多肽,副产物主要包括C端丢失1个氨基酸所形成的四肽,以及由于甲硫氨酸残基氧化而形成的含甲硫氨酸亚砜的多肽。该研究为高效合成含敏感氨基酸的生理活性多肽提供了新信息。     

Orientation Angle of Molecules at Hexadecane-Water Interface Studied with Total Internal Reflection Second Harmonic Generation

The orientation angle is an important parameter that reflects the structure of molecules at interfaces. In order to obtain this parameter, second order nonlinear spectroscopic techniques including second harmonic generation (SHG) and sum frequency generation-vibrational spectroscopy (SFG-VS) have been successfully applied through analysis of the nonlinear signal from various polarizations. In some SHG and SFG-VS experiments, total internal reflection (TIR) configuration has been adopted to get enhanced signals. However, the reports on the detailed procedure of the polarization analysis and the calculation of the orientation angle of interfacial molecules under TIR configuration are still very few. In this paper, we measured the orientation angles of two molecules at the hexadecane-water interface under TIR and Non-TIR experimental configurations. The results measured from polarization analysis in TIR configuration consist with those obtained from Non-TIR configuration. This work demonstrates the feasibility and accuracy of polarization analysis in the determination of the orientation angle of molecules at the interfaces under TIR-SHG configuration.     

波纹状银纳米线的制备及其SERS性能研究

首先通过传统的多元醇方法合成了表面光滑的银纳米线,然后利用Fe（NO₃）₃作为刻蚀剂在室温条件下对合成的银纳米线进行刻蚀得到了具有波纹状表面的银纳米线. 通过扫描电镜（SEM）分析表明：银纳米线的表面粗糙程度随着刻蚀剂量的增加而增加,但过量的刻蚀剂又会导致纳米线的断裂甚至形成球状颗粒;当刻蚀剂的量为100 μL时,获得了波纹状表面的银纳米线. 对结晶紫（CV）的表面增强拉曼光谱（SERS）结果表明,这种波纹状银纳米线的拉曼信号强度比表面光滑的银纳米线提高了约5倍,其检测限可低至10^-10 mol/L. 此外,这种优势还可以延伸到敏感性检测10^-9 mol/L的对巯基吡啶（4-Mpy）分子,可以作为一种普适、有效的SERS活性基底.     

2 D Manganese Vanadate Nanoflakes as High‐Performance Anode for Lithium‐Ion Batteries

Nanometer‐sized flakes of MnV₂O₆ were synthesized by a hydrothermal method. No surfactant, expensive metal salt, or alkali reagent was used. These MnV₂O₆ nanoflakes present a high discharge capacity of 768 mA h g^?1 at 200 mA g^?1, good rate capacity, and excellent cycling stability. Further investigation demonstrates that the nanoflake structure and the specific crystal structure make the prepared MnV₂O₆ a suitable material for lithium‐ion batteries.     

Multi‐walled carbon nanotube modified dummy‐template magnetic molecularly imprinted microspheres as solid‐phase extraction material for the determination of polychlorinated biphenyls in fish

Novel multi‐walled carbon nanotube modified dummy‐template molecularly imprinted microspheres (MWCNTs@DMMIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs). MWCNTs@DMMIPs were prepared by a surface molecular imprinting technique. Core–shell Fe₃O₄@SiO₂ nanoparticles were employed as magnetic support. 3,4‐Dichlorobenzene acetic acid was used as a dummy template instead of PCBs, methacrylic acid was used as functional monomer and ethylene glycol dimethacrylate was used as the cross‐linker. The resulting absorbent was characterized by various methods. The adsorbent was employed for extracting PCBs and exhibited good selectivity and high adsorption efficiency. Furthermore, it was reusable and capable of magnetic separation. Adsorption kinetics fit well with a pseudo‐second‐order kinetic equation and also exhibited a three‐stage intra‐particle diffusion model. The Freundlich model was used to describe the adsorption isotherms. The materials were successfully applied to the magnetic dispersive solid‐phase extraction of six kinds of PCBs followed by gas chromatography with mass spectrometry determination in fish samples, the limit of detection of six kinds of PCBs were 0.0028–0.0068 μg/L and spiked recoveries ranged between 73.41 and 114.21%. The prepared adsorbent was expected to be a new material for the removal and recovery of PCBs from contaminated foods.