信号处理方法在电分析化学中的应用

评述了数字信号处理方法在电分析化学中进展，着重介绍了这些方法的基本原理及其在电分析化学中的应用．     

Determination and on-line clean-up of (fluoro)quinolones in bovine milk using column-switching liquid chromatography fluorescence detection

A simple, cost-effective, and high throughput method using on-line column-switching liquid chromatography fluorescence detection was developed and validated for analysing five (fluoro)quinolones (FQs)--enrofloxacin (ENRO), ciprofloxacin (CIPR), sarafloxacin (SARA), oxolinic acid (OXOL), and flumequine (FLUM) in bovine milk. Norfloxacin (NORF) and nalixidic acid (NALI) were used as internal standards. After simple deproteination of milk sample with 5% (w/v) metaphosphoric acid, the supernatant was subject to on-line column clean-up and direct analysis by LC-FLD. The extraction cartridge was prepared in-house by slurry packing with hydrophilic-lipophilic polymer sorbent. The accuracy of measurement for each (fluoro)quinolone at different maximum residue limits (MRL) was 101-103% (ENRO), 92.8-97.4% (CIPR), 89.8-92.8% (SARA), 116-121% (OXOL), and 81.3-85.5% (FLUM), whilst the precision was 2.9-6.1% (ENRO), 2.5-5.1% (CIPR), 2.3-5.0% (SARA), 3.1-5.9% (OXOL), and 5.6-6.5% (FLUM). The decision limits, detection capabilities, specificity and analytes stability during storage were also investigated.     

Growth of Au nanoparticles on phosphorylated zein protein particles for use as biomimetic catalysts for cascade reactions at the oil–water interface

Chemo-enzymatic cascade processes are invaluable due to their ability to rapidly construct high-value products from available feedstock chemicals in a one-pot relay manner. However, they have proven to be challenging because of the mutual inactivation of both catalysts. A conceptually novel strategy based on Pickering interfacial catalysis (PIC) is proposed here to address this challenge. This study aimed to construct a protein-stabilized Pickering system for biphasic cascade catalysis, enabled by phosphorylated zein nanoparticles (ZCPOPs) immobilized in gold nanoparticles (Au NCs). Ultra-small Au NCs, 1–2 nm in diameter, were integrated into ZCPOPs at room temperature. Then, the as-synthesized ZCPOPs–Au NCs were used to stabilize the oil-in-water (o/w) Pickering emulsion. Besides their excellent catalytic activity and recycling ability in a variety of oil phases, ZCPOPs–Au NCs possess unpredictable catalytic activity and exhibit mimicking properties of horseradish peroxidase. Particularly, the cascade reaction is well achieved using a metal catalyst and a biocatalyst at the oil–water interface. The result showed that such a combination of chemo- and biocatalysis improved the catalytic yield more than two times compared with that of sole metal catalysis. This study opened a new avenue to design nanomaterials using the combination of chemo- and biocatalysis in a Pickering emulsion system for multistep syntheses.

A robust chemo- and biocatalytic cascade PIC with a recovery catalyst and a separation product was developed. The results groundbreakingly highlighted the preliminary applications of artificial enzymes and bio-enzymes in a one-pot cascade PIC.     

REVERSIBLE PHOTODIMERIZATION OF ANTHRACENE AND TETRACENE

Abstract— Dianthracene is efficiently photodissociated, forming anthracene with a quantum yield of about 0.63. Like anthracene, tetracene undergoes a reversible photochemical reaction, the product of which appears to be di-tetracene. In dilute, deoxygenated solutions the of quantum yeild for the formation of di-tetracene is directly proportional to the concentration of the monomer ødim = 2.2 (). The quantum yield for the reverse reaction is approximately 0.74
When dilute deaerated solutions of anthracene are irradiated with the unfiltered radiation from a quartz-mercury arc, a degradation product is formed. Unlike the dimer, this product cannot be converted into anthracene either by heating it to 200C or by irradiating it in solution with light of 254 nm. This degradation product appears to be the compound or compounds which Birks et al. believed to be dianthracene. Irradiation of deaerated solutions of anthracene (or tetracene) with light of wavelenghts longer than 300 nm produces only the dimer, which has an absorption spectrum similar to that reported by Coulson et al.     

Synthetic biohybrid peptidoglycan oligomers enable pan-bacteria-specific labeling and imaging: in vitro and in vivo

Peptidoglycan is the core component of the bacterial cell wall, which makes it an attractive target for the development of bacterial targeting agents. Intercepting its enzymatic assembly with synthetic substrates allows for labeling and engineering of live bacterial cells. Over the past two decades, small-molecule-based labeling agents, such as antibiotics, d-amino acids or monosaccharides have been developed for probing biological processes in bacteria. Herein, peptidoglycan oligomers, substrates for transglycosylation, are prepared for the first time using a top-down approach, which starts from chitosan as a cheap feedstock. A high efficiency of labeling has been observed in all bacterial strains tested using micromolar substrates. In contrast, uptake into mammalian cells was barely observable. Additional mechanistic studies support a hypothesis of bacteria-specific metabolic labeling rather than non-specific binding to the bacterial surface. Eventually, its practicality in bacterial targeting capability is demonstrated in resistant strain detection and in vivo infection models.

Peptidoglycan oligomers have been derived from chitosan, using a top-down bio-hybrid strategy, as highly bacteria-specific substrates.     

Wavelet frequency spectrum and its application in analyzing an oscillating chemical system

Based on the continuous wavelet transform (CWT), three types frequency spectra, wavelet frequency spectrum (WFS), point frequency spectrum (PFS) and time frequency spectrum (TFS), were developed. Two data sets were simulated and treated with the proposed spectra, the results indicated that WFS could extract the frequency information, which was like Fourier analysis but more accurate, PFS could obtain the frequency at any moment, TFS could show frequency change with time. These abilities of PFS and TFS were impossible for Fourier analysis. An oscillating chemical signal was processed with WFS and TFS. From the processed results, two points could be learned about the oscillating chemical reaction: one was the oscillating chemical reaction was a mixture one including two or more complex kinetics processes, the velocity of the switch from the reduced state (RS) to the oxidized state (OS) was faster than the reverse switch (from OS to RS); the other was increase of KBrO₃ could decrease the velocities of both switches, which led to the oscillating period became longer.     

一种新型手性席夫碱的合成及其在不对称环丙烷化反应中的催化性能

在不对称催化的发展过程中,设计与合成新的手性配体一直是人们所关注的热点,并已取得很大的进展[1].     

金纳米棒/石墨相氮化碳复合薄膜的制备及其光电化学性能

石墨相氮化碳(g-C₃N₄)作为一种新型的非金属有机半导体材料在光催化领域受到了人们的广泛关注。 为进一步改善它的光电化学性能,本文利用种子生长法和一锅法相结合制备了Au纳米棒/g-C₃N₄复合材料。 结果表明,金纳米棒降低了载流子的复合率,使复合材料表现出了较好的光电化学性能。 该材料光电流密度可达到17.18 μA/cm²(相对于可逆氢电极),是纯的石墨相氮化碳材料的2.5倍。