Synthesis of Highly Efficient Ag@AgCl Plasmonic Photocatalysts with Various Structures

By means of a simple ion‐exchange process (using different precursors) and a light‐induced chemical reduction reaction, highly efficient Ag@AgCl plasmonic photocatalysts with various self‐assembled structures—including microrods, irregular balls, and hollow spheres—have been fabricated. All the obtained Ag@AgCl catalysts were characterized by means of X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning electron microscopy, and UV‐visible diffuse reflectance spectroscopy. The effect of the different morphologies on the properties of the photocatalysts was studied. The average content of elemental Ag in Ag@AgCl was found to be about 3.2 mol %. All the catalysts show strong absorption in the visible‐light region. The obtained Ag@AgCl samples exhibit enhanced photocatalytic activity for the degradation of organic contaminants under visible‐light irradiation. The stability of the plasmonic photocatalysts was also investigated in detail.     

Development of a molecularly imprinted polymer for the analysis of avermectin

Five molecularly imprinted polymers (MIPs) were synthesized for a large molecule, avermectin, using different preparation techniques, monomers, and polymerization solvents. Selectivities (α) of each were compared using HPLC and different mobile phases containing various levels of acetic acid. Selectivity (α) for avermectin was greatest (α estimated ≥18) when the polymer was prepared non-covalently (utilizing only non-covalent interactions between avermectin and monomer) in chloroform using methacrylic acid (MAA) monomer and evaluated in chloroform. When evaluated in acetonitrile, an MIP prepared in acetonitrile provided better selectivity (α=8.4) than the polymer prepared in chloroform. Optimizing mobile phase conditions by adding acetic acid was much more important when MIPs were evaluated in chloroform than in acetonitrile. MIPs prepared with MAA provided better selectivity than a polymer prepared with acrylamide monomer. Covalent preparation of two MIPs utilizing a covalent bond between avermectin and monomer before polymerization did not improve selectivity but did improve peak shape in chromatograms. Specificity was demonstrated by comparing the selectivity of avermectin with eprinomectin (α=3.0), a compound with a very similar structure. Results indicate that an MIP can be prepared for the large avermectin molecule, and has the potential to simplify sample preparation and to reduce the time needed for analysis.     

Characterization of phosphate solubilizing bacteria in sediments from a shallow eutrophic lake and a wetland: isolation, molecular identification and phosphorus release ability determination

The transformation of phosphorus (P) is a major factor of lake eutrophication, and phosphate releasing bacteria play an important role in the release process. Experiments were conducted to investigate P content and characterize phosphate solubilizing bacterial composition at the molecular level in a shallow eutrophic lake and a wetland. Results showed that P concentrations were relatively high and derived from agricultural runoff and domestic or industrial pollution. Enumeration and molecular identification of these strains indicated that these bacterial groups were abundant in the ecosystem and various kinds of bacteria participated in the phosphorus release process. Twelve phosphate solubilizing bacteria, including eight organic P-solubilizing bacteria (OPBs) and four inorganic P-solubilizing bacteria (IPBs), which belonged to three different families, were isolated and identified. Cupriavidus basilensis was found for the first time to have the ability to mineralize organic P (OP). Laboratory tests on P release ability revealed that IPBs were more effective at releasing P than OPBs. The most efficient IPB strain could accumulate over 170 mg·L-1 orthophosphate, while the equivalent OPB strain only liberated less than 4 mg·L-1 orthophosphate in liquid culture. The results obtained from this investigation should help clarify the roles of microorganisms in aquatic systems and the mechanisms of eutrophication.     

Voltammetric behavior of mammalian tumor cells and bioanalytical applications in cell metabolism

The voltammetric behavior of human mammalian cells was studied by choosing human leukemia cells (HL60) and human erythroleukemia cells (HEL). The voltammetric response of the cells was found having relation with cell metabolic viability in culture course. For example, the fluctuations of peak currents of HL60 were parallel with the nutrients replenished or not, which can reflect cell health state; the voltammetric response of HL60 regulated by the anti-metabolic drug 5F-Uriacil (5F-U) in culture course behaved in a much decreased manner, by which a voltammetric method for evaluating cytotoxicity is proposed. In this paper, the relation between HEL cell metabolism and the activation of receptor Mpl by its ligand TPO was also studied. Moreover, the mechanism of cell voltammetric behavior was discussed.     

Ionic liquid-based ultrasonic/microwave-assisted extraction combined with UPLC-MS-MS for the determination of tannins in Galla chinensis

Ionic liquid was used as extraction solvents and applied to the extraction of tannins from Galla chinensis in the simultaneous ultrasonic- and microwave-assisted extraction (UMAE) technique. Several parameters of UMAE were optimised, and the results were compared with of the conventional extraction techniques. Under optimal conditions, the content of tannins was 630.2?±?12.1?mg?g?1. Compared with the conventional heat-reflux extraction, maceration extraction, regular ultrasound- and microwave-assisted extraction, the proposed approach exhibited higher efficiency (11.7-22.0% enhanced) and shorter extraction time (from 6?h to 1?min). The tannins were then identified by ultraperformance liquid chromatography tandem mass spectrometry. This study suggests that ionic liquid-based UMAE is an efficient, rapid, simple and green sample preparation technique.     

Chemical constituents of Asplenium ruta-muraria L

A phytochemical study of Asplenium ruta-muraria L. (Aspleniaceae) led to the isolation of a new caffeic acid glycoside, 2-O-caffeoyl-β-D-fructofuranosyl-(2?→?1)-α-D-glucopyranoside and an (α, β)-isomeric pair of 2E-caffeoyl-D-glucopyranoside, together with kaempferol-3-O-β-D-[6-E-caffeoyl-β-D-glucopyranosyl-(1?→?2)glucopyranoside]-7-O-β-D-glucopyranoside, 1-O-caffeoyl glycoside, sucrose, diploptene and β-sitosterol. Their structures were established by means of MS and capillary NMR techniques. Additionally, aromatase inhibitory activity of the extracts and phenolic compounds was evaluated.     

Needle trap extraction for GC analysis of formic and acetic acids in aqueous solution

Formic and acetic acids are ubiquitous in the environment, food, and most of the natural products. Extraction of the acids from aqueous solution is required for their isotope analysis by the gas chromatography-isotope ratio mass spectrometry. To this objective, we have previously developed a purge-and-trap technique using the dynamic solid-phase microextraction technology, the NeedlEX. The extraction efficiency, however, remains unexamined. Here, we address this question using the flame ionization detector and isotope ratio mass spectrometer while comparing it with that of the CAR/PDMS fiber. The results show that the NeedlEX is applicable at a wide range of concentration through coordination of purge volume given the minimum amount 3.7 ng and 1.8 ng of formic and acetic, respectively, is extracted. The efficiency of NeedlEX was 6-7 times lower than the fiber at 1000 μg/mL depending on the analyte. It is, however, superior to the latter at 10 μg/mL or less owing to its lower detection limit. The extraction efficiency of both acids is equivalent in molar amount. This is, however, disguised by the different response of the flame ionization detector. The isotope ratio mass spectrometor overcomes this problem but is compromised by relatively large errors. These results are particularly useful for isotopic analysis of carboxylic acids.     

Theoretical analysis of structure, thermodynamic properties, and optical properties of Ge-doped amorphous SiO2

Different stable geometric configurations of Ge doped amorphous SiO₂ (a-SiO₂) system, originating from one, two, or three Si atoms in various places of the a-SiO₂ substituted by Ge atoms randomly have been investigated using interatomic potentials in this work. The most stable structures have been identified and corresponding evolutional rules obtained. The structural growth pattern for Ge-doped a-SiO₂ system is that Ge atoms tend to spread far away from each other and keep away from the center. Furthermore, the thermodynamic properties including speci?c heat, Debye temperature, vibrational entropy, and so on are calculated from the structure with 16 Si atoms of the constructed a-SiO₂ cell replaced by Ge atoms and with the biggest Ge-Ge distance. It can be seen that entropy of Ge doped system with larger specific heat is higher than that of the pure system with smaller specific heat. At last, optical properties including optical absorption spectrum and electron energy loss function of nGe-doped a-SiO₂ (n=0-3, 8) system is also obtained.     

An indirect approach for anion detection: the displacement strategy and its application

The development of new optical anion chemosensors with high sensitivity and selectivity is very important, since anions possess some fundamental roles in a wide range of biological and chemical processes. The displacement approach is a method using anion binding sites and signaling subunits, which are not covalently attached but forming a coordination complex, in which the presence of anions revives the noncoordinated spectroscopic behavior of the indicator. In the past five years, according to the displacement strategy, many good optical anion chemosensors have been successfully obtained. This paper reviews the recent progress in the field of the fluorescent and colorimetric anion chemosensors designed according to the displacement strategy (mainly from 2008 to 2011), and gives some outlooks for the further exploration of new optical anion chemosensors.