Search

Ion Mobility Spectroscopy (IMS) is commonly used for in-situ rapid online detection of trace substances at atmospheric pressure. By selecting four types of Phthalic acid Ester (PAE) compounds as the quantitative research objects, studying the effects of the temperature of the mobility tube, the temperature of the sample desorbed heater and the electric field strength of the mobility region on the detection, analysing the microscopic process of ion reaction after the addition of reagent molecules using the Rectilinear Ion Trap Mass Spectrometer (RIT-MS), the paper preliminary studies the product ions of phthalic acid ester, and establish a method for rapid measurement of phthalic acid ester-like environmental hormones with ion mobility spectrometry. With the addition of ammonia reagent molecules, the detection limits of dimethyl phthalate, diethyl phthalate, dibutyl phthalate and butyl benzyl phthalate were 0.08 and 0.1, 0.09, 0.70 ng, respectively, and relative standard deviation RSD of 6 parallel measurements <6.3%. When used for the detection of phthalates in plastics, this method can quickly and easily screen products containing trace PAE-like contaminants. [ABSTRACT FROM AUTHOR]

When the dimensionality of layered compounds decreases to the physical limit, ultimate two-dimensional (2D) anisotropy and/or quantum confinement effects may lead to extraordinary physicochemical attributes. Here, we report single-layer Rh nanosheets (NSs) exhibiting ultrahigh peroxidase-like activity, far exceeding that of horseradish peroxidase (HRP) and of most known layered nanomaterial-based peroxidase mimics. Considering per NS as an active subunit, the Rh NSs displayed a catalytic rate constant (Kcat) as high as 4.45 × 105 s-1 to H2O2, two orders of magnitude higher than those of HRP and Rh nanoparticles. The high atom efficiency of the Rh NSs can be attributed to the full exposure of surface-active Rh atoms, which greatly facilitates electron transfer and formation of superoxide anions, representing reactive oxygen species in the catalytic process. As a proof-of-concept application, the Rh NSs were successfully used as peroxidase mimics for the colorimetric detection of H2O2 and xanthine, with high sensitivity and selectivity. Moreover, a simple, rapid, and sensitive Rh-based paper sensor for ascorbic acid was also developed. In summary, this work provides a novel example of single-layer metallic NSs for biosensing. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) supported HSiW/MWCNTs was successfully prepared and characterized by Fourier transform infrared spectoscopy, X-ray powder diffraction, transmission electron microscopy and N adsorption-desorption test. Its catalytic performance for the catalytic Baeyer-Villiger oxidation of cyclic ketones with 30 % HO as oxidants was investigated. It was found that HSiW/MWCNTs was very efficient to transform of some cycloketones to the corresponding lactones with high conversions as well as selectivities. Factors affecting the oxidations and the reusability of the catalyst were also investigated. It was found that the catalyst can be reused seven times in the catalytic oxidation reaction of cyclopentanone without obviously catalytic activity losing in the oxidation. Graphical Abstract: A supported solid acid of HSiW/MWCNTs was used as efficient catalyst for the Baeyer-Villiger oxidation of ketones. High cyclopentanone conversion (98 %) and ε- valerolactone selectivity (99 %) were obtained. The catalyst can be reused at least seven runs in the oxidation of cyclopentanone.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

An amphipathic highly branched diblock polyether, PA60-2-40, was synthesized via anion ring-opening polymerization of propylene oxide (PO) and ethylene oxide (EO), using phenol-amine resin (PA) as the initiator. The molecular structure was confirmed by FT-IR and 1H NMR. The surface tension and fluorescence spectroscopy measurements provide information about the effect of cosolvents on the critical micelle concentration (CMC) and the standard Gibbs energy (ΔG omic). The cosolvents have a significant effect on the CMC of PA60-2-40; the CMC first decreases and then increases with increasing content of n-pentanol, but with an increase of ethylene glycol concentration, there is durative decrease of the CMC. The micellization becomes more spontaneous in the presence of cosolvents with more hydroxyl groups, but the CMC does not monotonically increase or decrease with the increasing carbon chain length of aliphatic monohydric alcohols. The values of surface activity parameters (Г max, A min and ∆G omic) calculated all coincide with the results of the experiment. Additionally, TEM and DLS demonstrate that the size of the micelles can be changed by the addition of alcohols, but the aggregation morphology will not change. [ABSTRACT FROM AUTHOR]