Facile Assembly of Graphene on Anion Exchange Resin Microspheres for Electrochemical Sensing and Biosensing

Graphene sheets were assembled on anion exchange resin (AER) microspheres based on the electrostatic interactions between graphene oxide and AER and subsequent chemical reduction. The prepared graphene‐coated AER microspheres were characterized by scanning electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy. They were then embedded in the bores of pipette tips to fabricate disposable electrodes for electrochemical sensing. The workability and performance of the novel electrodes were examined by analyzing the electrochemical behavior of the electrodes for the sensing of ascorbic acid, dopamine, uric acid, acetaminophen, aniline, and glucose by cyclic voltammetry and amperometry. The advantages of the electrodes include ease of fabrication, low cost, pronounced electrocatalytic activity, and rapid response. Thus, they hold great promise for a wide range of applications.     

Surface‐Passivated SBA‐15‐Supported Gold Nanoparticles: Highly Improved Catalytic Activity and Selectivity toward Hydrophobic Substrates

Silanol groups on a silica surface affect the activity of immobilized catalysts because they can influence the hydrophilicity/hydrophobicity, matter transfer, or even transition state in a catalytic reaction. Previously, these silanol groups have usually been passivated by using surface‐passivation reagents, such as alkoxysilanes, bis‐silylamine reagents, chlorosilanes, etc., and surface passivation has typically been found in mesoporous‐silicas‐supported molecular catalysts and heteroatomic catalysts. However, this property has rarely been reported in mesoporous‐silicas‐supported metal‐nanoparticle catalysts. Herein, we prepared an almost‐superhydrophobic SBA‐15‐supported gold‐nanoparticle catalyst by using surface passivation, in which the catalytic activity increased more than 14 times for the reduction of nitrobenzene compared with non‐passivated SBA‐15. In addition, this catalyst can selectively catalyze hydrophobic molecules under our experimental conditions, owing to its high (almost superhydrophobic) hydrophobic properties.     

Study of the Phase Transformation of Single Particles of Ga2O3 by UV‐Raman Spectroscopy and High‐Resolution TEM

By taking advantage of UV‐Raman spectroscopy and high‐resolution TEM (HRTEM), combined with the focused ion beam (FIB) technique, the transformation from GaOOH into α‐Ga₂O₃ and then into β‐Ga₂O₃ was followed. We found that the stepwise transformations took place from the surface region before developing into the bulk of single particles without particle agglomeration and growth. During the transformation from GaOOH into α‐Ga₂O₃, the elimination of water vapor through the dehydroxylation of GaOOH resulted in the formation of micropores in the single particles, whilst maintaining their particle size. For the phase transformation from α‐Ga₂O₃ into β‐Ga₂O₃, the nucleation of β‐Ga₂O₃ was found to occur at the surface defects and this process could be retarded by occupying these defects with a small amount of La₂O₃. By finely controlling the process of the phase transformation, the β‐Ga₂O₃ domains gradually developed from the surface into the bulk of the single particles without particle agglomeration. Therefore, the surface structure of the α‐Ga₂O₃ single particles can be easily tuned and a particle with an α@β core–shell phase structure has been obtained.     

Quantification and pharmacokinetics of Taiwanin E methyl ether in rats by liquid chromatography–tandem mass spectrometry

This study firstly describes the development of an accurate and sensitive high‐performance liquid chromatography–tandem mass spectrometry (LC‐MS/MS) assay for the quantification of Taiwanin E methyl ether (TEME) in rat plasma. The assay involved a simple liquid–liquid extraction step with ethyl acetate and a gradient elution using a mobile phase consisting of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid. Chromatographic separation was successfully achieved on an Agilent Zorbax‐C₁₈ column (2.1 × 50 mm, 3.5 µm) with a flow rate of 0.40 mL/min. The multiple reaction monitoring was based on the transitions of m/z = 379.1 → 320.1 for TEME and 386.1 → 122.0 for buspirone (internal standard). The assay was validated to demonstrate the specificity, linearity, recovery, accuracy, precision and stability. The lower limit of quantification was 0.50 ng/mL in 50 μL of rat plasma. The developed and validated method was successfully applied to the quantification and pharmacokinetic study of TEME in rats after intravenous and oral administration of 1.45 mg/kg TEME. The oral absolute bioavailability of TEME was estimated to be 5.85 ± 1.41% with an elimination half‐life value of 2.61 ± 0.55 h, suggesting its poor absorption and/or strong metabolism in vivo. Copyright © 2012 John Wiley & Sons, Ltd.     

The Reaction Activity of Aromatic Carbonyl Compounds with Diphenylphosphine Oxide Studied by 31P NMR

Abstract

A series of α-hydroxyphosphine oxides were prepared by the reactions of diphenylphosphine oxide and aromatic carbonyl compounds and characterized by ¹H NMR, ¹³C NMR, ³¹P NMR, FT-IR, ESI-MS, and HR-MS spectra. The reaction rates and experimental conditions of aromatic aldehydes and aromatic ketones were obviously different due to the activity of their carbonyls. The different substituents of the aromatic aldehydes affected the reaction rate too, and the quantitative reactivity of their substituent conformed to the Hammett equation. The results were confirmed by ³¹P NMR spectroscopy.     

高质量NaNdF4六方棱柱纳米棒的水热形貌控制合成及发光性质

采用水热法在温和的条件下合成了具有规则外形的六方棱柱状NaNdF₄纳米棒。X射线衍射（XRD）分析表明：产物为纯六方相NaNdF₄,场发射扫描电镜（SEM）分析表明产物形貌为棱柱状纳米棒,长约为550nm,棒的端部呈规则六边形,边长约为85nm。高分辨透射电子显微镜（HRTEM）和选区电子衍射（SD）显示所得样品为良好的单晶。NaNdF₄晶体的生长动力学过程表明：螯合剂（EDTA-Na₂）与稀土金属离子间的螯合作用受pH值影响,导致成核速度变化,进而影响NaNdF₄纳米晶的最终尺寸和形貌。室温下的NaNdF₄纳米棒的发光峰位于红外光范围（λ=892,1058,和1342nm）,其最强发射峰位于1058nm,对应于Nd³⁺的⁴F_3/2→⁴I_11/2f-f跃迁。     

Synthesis of Main‐Chain Liquid‐Crystalline Polyesters Containing Diphenyl Mesogens by Chemo‐Enzymatic Route †

Main‐chain thermotropic liquid‐crystalline polyesters containing rigid biphenyl mesogens and flexible spacers were synthesized by chemo‐enzymatic route. The enzyme‐catalyzed polymerization showed high regio‐ and chemo‐ selectivity, and is environmentally friendly. The resulting polyesters were characterized with ¹H‐NMR, ¹³C‐NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and polarized light optical microscopy (POM).     

Synthesis and Characterization of Amphiphilic Copolymer Acrylic Acid-co-p-Chloromethylstyrene

The free radical copolymerization of acrylic acid (M₁) with p-chloromethylstyrene (M₂) in dioxane and in the presence of α,α′-azobisisobutyronitrile (AIBN) at 65°C is reported. Copolymer compositions of six copolymer samples obtained from feed ratios of M₁:M₂ = 95.2:4.8 to 21.4:78.6 were determined by ¹H-NMR. The reactivity ratios of AA/p-CMS copolymerization system calculated by the F-R method were r ₁ = 0.50 ± 0.06 and r ₂ = 1.52 ± 0.15, almost the same as r ₁ = 0.43 ± 0.21 and r ₂ = 1.31 ± 0.14 by the extended K-T method. On the basis of the reactivity ratios of two monomers, the sequence length distribution in the AA/p-CMS copolymers was obtained. For f₂ = 4.77%, the monomer unit of p-CMS is individually separated in the chain of AA; for f₂ = 35.53%, the alternating tendency prevails and a large number of mono-sequences are formed. The number-average ( _n) and weight-average ( _w) molecular weights were determined by gel permeation chromatography. The effect on molecular weights of feed composition is also discussed. In the presence of constant initiator concentration, the gradual increase in the ratio of M₂:M₁ (from14.7:85.3 to 78.6:21.4) was accompanied by a decrease in molecular weights ( _n from 11907 to 3961).