SnFe2O4 Nanocrystals as Highly Efficient Catalysts for Hydrogen‐Peroxide Sensing

SnFe₂O₄ nanocrystals (NC), prepared with a simple one‐step carrier‐solvent‐assisted interfacial reaction process, were developed as highly efficient catalysts for hydrogen peroxide sensing. These NCs, with a size of around 7 nm, served as the sensing catalyst and were decorated onto the pore surfaces of a porous fluorine‐doped tin oxide (PFTO) host electrode, prepared from commercial FTO glass with a simple anodic treatment, to form the sensing electrode for hydrogen peroxide. The SnFe₂O₄ NCs‐loaded PFTO electrode exhibited an ultra‐high sensitivity of 1027 mA m ^?1 cm^?2 toward hydrogen peroxide, outperforming Pt NCs‐loaded PFTO electrodes. The SnFe₂O₄ NCs‐loaded PFTO electrode proved a promising relatively low cost, high performance sensing electrode for hydrogen peroxide.     

Full-capillary sample stacking/sweeping-MEKC for the separation of naphthalene-2,3-dicarboxaldehyde-derivatized tryptophan and isoleucine

In an attempt to improve the sensitivity of detection in capillary electrophoresis (CE), a novel online sample-concentration method, full-capillary sample stacking (FCSS)/sweeping-micellar electrokinetic chromatography (sweeping-MEKC) mode, is proposed. Naphthalene-2,3-dicarboxaldehyde (NDA)-derivatized tryptophan and isoleucine were selected as model compounds. In the initial step, the weakly acidic compounds, dissolved in a low-conductivity buffer (35.1 microS/cm; apparent ph (pH*) in a mixed solution of acetonitrile/methanol/water, 4.6), fill the entire capillary, two vials of a high-conductivity buffer (2.06 mS/cm; pH* 2.0) are placed on each end, and a negative polarity is then applied. Under these conditions, the direction of the electroosmotic flow (EOF) is toward the inlet. Meanwhile, the anionic analytes move in the reverse direction and are neutralized and stacked at the boundary of a dynamic pH-junction (between the sample matrix and the nonmicellar background solution (BGS)). When the sample concentration is completed, the BGS is quickly changed to solutions containing SDS-BGS for the subsequent separation. Since the mobility of SDS-analytes is then greater than the EOF, the following steps occur by the sweeping (for focusing) and MEKC (for separation) mode. Using these steps, a full-capillary sample injection/separation can be achieved.     

Kinetics of Phase Transfer Catalytic Preparation of Benzyl Phenyl Ether

Benzyl phenyl ether is prepared in a well-stirred batch reactor from phenol and benzyl chloride using tetrabutylammonium iodide as phase transfer catalyst. Phenol with sodium hydroxide is dissolved in water as the aqueous phase, and benzyl chloride is dissolved in toluene as the organic phase. Tetrabutylammonium iodide gives high reaction rate without the formation of micelles during the reaction. The reaction mechanism is verified by infrared spectrum study and other experimental observations. The kinetics of the reaction of benzyl chloride is modelled as a first-order chemical reaction. The cocatalytic effect of the iodide ion, and salting out effect on the overall reaction rate are discussed in detail using experimental data.     

Periodic extinction bands composed of all flat‐on lamellae in poly(dodecamethylene terephthalate) thin films crystallized at high temperatures

Using in‐house synthesized poly(dodecamethylene terephthalate) (P12T) as a model, periodic extinction‐banded spherulites melt‐crystallized at high T_cs (100–115 °C) are expounded in terms of growth mechanism. The extinction‐banded spherulites wildly differing from the usual blue/orange double ring‐banded spherulites are composed of all flat‐on discrete single‐crystalline lamellae packed like roof shingles (or fish scales) along the circularly curved bands and the lamellae in the extinction bands are flat with a lozenge shape with no continuous twisting at all. For P12T films of more than 10 µm crystallized at T_c = 105–115 °C, no periodic bands were seen, and all spherulites were ringless, where periodic growth precipitation of crystals to extinction does not occur until impingement. Extinction bands in the P12T spherulites with the inter‐ring spacing steadily decrease with decreasing film thickness, because for thinner films (submicrons to 2 µm), draining or depletion of available molten species takes place more frequently, leading to bands of smaller inter‐ring spacing. The petal‐like extinction bands are discussed and analyzed in detail using 3D AFM imaging. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 601–611