Removal of radiocobalt from aqueous solution by Mg2Al layered double hydroxide

The adsorption behavior of radiocobalt by Mg₂Al layered double hydroxide (Mg₂Al LDH) was studied as a function of contact time, pH, ionic strength, foreign ions, FA and temperature under ambient conditions. The results showed that the kinetic adsorption could be described by a pseudo-second order model very well. The adsorption of Co(II) on Mg₂Al LDH was strongly dependent on pH and ionic strength. The presence of FA enhanced the adsorption of Co(II) on Mg₂Al LDH at low pH, whereas reduced Co(II) adsorption at high pH. The Langmuir model fitted the adsorption isotherms of Co(II) better than the Freundlich and D–R model at three different temperatures of 303, 323 and 343 K. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature dependent adsorption isotherms indicated that the adsorption process of Co(II) on Mg₂Al LDH was endothermic and spontaneous. The results show that Mg₂Al LDH is a promising material for the preconcentration and separation of pollutants from large volumes of aqueous solutions.     

Improvements in morphological and electro‐optical properties of polymer‐dispersed liquid crystal grating using a highly fluorine‐substituted acrylate monomer

To improve the morphological and electro‐optical properties of a polymer‐dispersed liquid crystal (PDLC) grating, a type of highly fluorine‐substituted acrylate monomer was added to the prepolymer mixture. The morphologies of the PDLC gratings were investigated using atom force microscopy and scanning electron microscopy. The grating had a very clear polymer/LC interface after addition of 3.9 wt % of fluorine‐substituted monomer. The LC droplets in this case were much larger than the sample without fluorinated monomer. This phenomenon indicated that an almost complete phase separation had occurred. However, as the content of fluorine‐substituted monomer increased, the morphologies of gratings became less defined and the volumes of LC droplets were smaller. The diffraction efficiency (DE) decreased with increasing of fluoride content and the V ₉₀ increased simultaneously, which may be ascribed to the blurry interface and the small LC droplets. The highest DE (90%) and lowest V ₉₀ (70 V) were obtained simultaneously under the condition of 3.9 wt % fluoride added in the prepolymer. In addition, it was also found that the fluorine‐substituted monomer may disorder the alignment of LCs in the grating.     

Photoalignment of liquid crystals by a covalently attached self-assembled ultrathin film

In this paper, the polyanion-containing cinnamoyl group (PACSS-CF3) was self-assembled with diazoresin (DR) to form a kind of stable covalent ultrathin film by irradiation with 365?nm UV light. The photoalignment properties of the DR/PACSS-CF₃ covalent film were investigated. The covalent film was found to have anisotropy after irradiation by 297?nm linearly polarised ultraviolet light (LPUVL), and could induce uniform alignment of liquid crystals (LCs). The pretilt angle of the LC was 2.5°. The stability of the film was enhanced by the covalent bonds. The films were thermally stable to 180°C. Polarised UV-Vis spectroscopy was utilised to investigate the photochemical process of the covalent film. It was found that cinnamoyl moieties parallel to the polarisation direction of the LPUVL were consumed by the photoreaction faster than those perpendicular to the polarisation direction. It can be concluded that the selective photoreaction induced the anisotropy of the films. The anisotropic films induced the homogeneous alignment of LC.     

反相离子对液相色谱测定葡萄糖化学氧化过程中的6种有机酸

建立了反相离子对液相色谱同时测定葡萄糖氧化产物:葡萄糖醛酸、葡萄糖酸、乙醇酸、乙酸、葡萄糖二酸及酒石酸含量的方法。采用kromasil C18色谱柱(250 mm×4.6 mm,5μm),流动相为10 mmol/L K2HPO4-10 mmol/L四丁基硫酸氢铵(pH 7.2):甲醇(95:5,V/V),检测波长210 nm,流速0.7 mL/min,进样量20μL。6种有机酸在线性范围内峰面积与浓度呈良好的线性关系;回收率为92.7%～107.0%;RSD(n=5)为0.9%～6.3%。20 min内即可将6种物质分开。对葡萄糖化学氧化过程检测表明,HNO3氧化法反应剧烈,除了生成葡萄糖酸、葡萄糖醛酸和葡萄糖二酸外,还生成碳-碳键断裂的副产物如酒石酸、乙醇酸等,而TEMPO法反应较为温和,并未发生碳-碳键断裂。     

两个含吡啶取代苯酚配体的铜配合物的合成与晶体结构

以2-[N,N-二(2-吡啶甲基)氨甲基]-6-醛基-4-甲基苯酚(L)为配体,合成了2个单核铜配合物[CuL(CH3CN)(ClO4)]ClO4(1)和cis-[CuL(NCS)2]·0.5C4H8O2(2),对它们进行了紫外、红外、质谱、元素分析和单晶结构表征。2个配合物都属于单斜晶系,每个铜均为扭曲的八面体构型。作为四齿配体,L通过2个吡啶氮原子,1个叔胺氮原子和1个酚氧原子和铜离子配位。在配合物1中,乙腈和1个ClO4-参与配位,而在配合物2中2个硫氰根离子为顺式配位。     

Conversion of CuO Nanoplates into Porous Hybrid Cu2O/Polypyrrole Nanoflakes through a Pyrrole‐Induced Reductive Transformation Reaction

Porous hybrid Cu₂O/polypyrrole nanoflakes have been synthesized from solid CuO nanoplate templates through the pyrrole‐induced reductive transformation reaction at elevated temperature. The conversion mechanism involves the reductive transformation of CuO to Cu₂O and the in situ oxidative polymerization of pyrrole to polypyrrole. In addition, the morphology of the as‐converted nanohybrids depends on the shape of the CuO precursors. The strategy enables us to transform single‐crystalline CuO nanosheets into hollow hybrid Cu₂O/polypyrrole nanoframes. The ability to transform CuO and an organic monomer into porous hybrid materials of conducting polymer and Cu₂O with macrosized morphological retention opens up interesting possibilities to create novel nanostructures. Electrochemical examinations show that these porous hybrid Cu₂O/polypyrrole nanostructures exhibit efficient catalytic activity towards oxygen reduction reaction (ORR), excellent methanol tolerance ability, and catalytic stability in alkaline solution, thus making them promising nonprecious‐metal‐based catalysts for ORR in alkaline fuel cells and metal–air batteries.     

A Serum‐Tolerant Hydroxyl‐Modified Polyethylenimine as Versatile Carriers of pDNA/siRNA

The polyethylenimine (PEI) derivatives (PTn) are prepared by treating PEI25k with Tris(hydroxymethyl) acrylamidomethane via the Michael addition. These PTns can effectively condense nucleic acids into nanosized particles with positive surface charges. The PTns show lower cytotoxicity and better serum‐resistant capacity than PEI25k. Specially, the transfection efficiency of PT26/DNA is 29‐fold higher than that of PEI25k in HeLa cells in serum‐containing medium. The PTn/siRNA complexes show superior knockdown effect in CT26 cells in serum‐containing medium. In addition, flow cytometry analysis shows that the PTns can efficiently mediate the entry of nucleic acids into the cell. Thus, PTns are potentially applicable as non‐viral carriers of nucleic acids and warrant further development for use in gene therapy.

     

Determination of Seven Odorants in Purified Water Among Worldwide Brands by HS-SPME Coupled to GC–MS

Musty and earthy odors dramatically influence the esthetic quality and consumer acceptability of drinking water. This study was conducted to obtain a sensitive method for simultaneous analysis of seven odors, including geosmin (GSM), 2-methylisoborneol (2-MIB), 2-isopropyl-3-methoxy pyrazine (IPMP), dimethyl trisulfide (DMTS), 2,4,6-trichloroanisole (2,4,6-TCA), β-cyclocitral, and β-ionone, in water by applying headspace solid phase micro-extraction coupled to gas chromatography with mass spectrometry. Moreover, the proposed method was applied to obtain preliminary understanding of the levels of these odorants in purified water among various brands in the world, and to try to find out the potential causes when the odorants appeared in purified water. The target compounds could be separated and analyzed effectively within 23 min, and the GSM and DMTS could be detected in all brands of chosen countries, while the IPMP, β-ionone and 2,4,6-TCA cannot be observed in the above brands.     

Novel Microporous Membrane/Solvent Microextraction for Preconcentration of Cinnamic Acid Derivatives in Rhizoma Typhonii

A novel microporous membrane/solvent microextraction (MPMSME) approach was developed in which a piece of microporous filter membrane was used as not only extraction solvent holder but also solid phase extraction unit. Subsequently, high-performance liquid chromatography with an UV detector was conducted. The wide exchange surface and very little organic solvent consumption made this sample pretreatment technology very interesting. The cinnamic acid derivatives were used as model analytes to evaluate the procedure. Parameters that affect the MPMSME such as type of extraction solvent, membrane area (or volumes of extraction solvent), aqueous phase pH, ionic strength, extraction stirring rate, extraction time, and sample volume were investigated and optimized. The enrichment factor (EF) of analyte was defined in MPMSME. Under the optimized conditions, the EFs of cinnamic acid derivatives were 43–144. Good linearities were obtained from 4 to 4,000 ng mL^?1 for all the analytes with regression coefficients of between 0.9956 and 0.9977; the limits of quantification were below 0.4 ng mL^?1, and satisfactory recoveries (93–106 %) and precisions (0.37–13 %) were also achieved. The experimental results showed that the method was simple, rapid, practical, and effective for preconcentration and determination of the cinnamic acid derivatives in rhizoma typhonii.     

Solvent Bar Microextraction with HPLC for Determination and Protein-Binding Characteristics of Oleanolic Acid and Ursolic Acid

An improved solvent bar microextraction (SBME) combined with HPLC was applied to rapidly determine oleanolic acid (OA) and ursolic acid (UA) in Chinese medicinal herbs (CMHs), and to investigate drug–protein binding. Variables influencing SBME were investigated and optimized. Under optimal conditions, the linear ranges of 3.6–1,820 ng mL^?1 for OA and 4.2–2,080 ng mL^?1 for UA were obtained with square correlation coefficients of 0.9996 and 0.9997, respectively. The detection limits were 1.3 ng mL^?1 for OA and 1.5 ng mL^?1 for UA. The relative standard deviations were lower than 9.4 %. The protein-binding rates, the numbers of binding sites, and the binding constants of OA and UA were also obtained via the method. It has been demonstrated that SBME can not only be a simple, rapid and efficient sample preparation method for determination of active components from CMHs but also be a potential research protocol for protein-binding interactions.