For developing highly selective and sensitive electrochemical sensors for chiral recognition, taking advantage of the synthetical properties of β-cyclodextrin (β-CD, strong host−guest recognition) and carbon nanotubes wrapped with reduced graphene oxide (CNTs@rGO, excellent electrochemical property and large surface area), as well as the differences in binding affinity between β-CD and guest molecules, a dual signal electrochemical sensing strategy was proposed herein for the first time in chiral recognition based on the competitive host−guest interaction between probe and chiral isomers with β-CD/CNTs@rGO. As a model system, rhodamine B (RhB) and phenylalanine enantiomers (Dand L-Phe) were introduced as probe and target enantiomers, respectively. Due to the host−guest interactions, RhB can enter into the β-CD cavity, showing remarkable oxidation peak current of RhB. In the presence of L-Phe, competitive interaction with the β-CD cavity occurs and RhB are replaced by L-Phe owing to the stronger binding affinity between L-Phe and β-CD, which results in the peak current of RhB decreasing and the peak current of L-Phe appears, and interestingly, the changes of both signals linearly correlate with the concentration of L-Phe. As for D-Phe, it cannot replace RhB owing to the weaker binding affinity between D-Phe and β-CD. Based on this, a dual-signal electrochemical sensor was developed successfully for recognizing Phe. This dual-signal sensing strategy can provide highly selective and sensitive recognition compared to single-signal sensor and has important potential applications in chiral recognition.C hirality has an important impact on chemical/biological research, since most active substances possess chirality. Generally, the performance of chiral enantiomers show great differences in terms of biochemical activity, toxicity, transport processes, and metabolic pathways. 1−3 Typically, only one isomer exhibits perfect activity and the other has no desirable value and even causes serious side-effects. Thus, chiral recognition is always a popular topic in chemical and biological research. 4−6 For resolving this problem, many approaches, such as capillary electrophoresis, 7 high-performance liquid chromatography, 8 circular dichroism spectroscopy, 9,10 colorimetry 11,12 and fluorescence, 13,14 were developed to recognize electroactive chiral molecules, which are very important in chiral recognition. However, the most of reported approaches need complex sample pretreatment and expensive chiral columns and are time-consuming as well. 15,16 Recently, electrochemical chiral recognition has received considerable attention, due to the many advantages they offer, such as low cost, fast response, inexpensive instrument, and facile miniaturization. 17−22 For instance, Kong et al. 23

A series of pyridinium and quaternary ammonium copper corroles has been designed and synthesized. All new compounds have been fully characterized by NMR spectroscopy, high-resolution mass spectrometry, UV/Vis spectrscopy, and elemental analysis. Biochemical studies have indicated that all of these corrole derivatives can stabilize G-quadruplex structures, with corrole 4 being the most effective according to the results of circular dichroism (CD) melting experiments, polymerase chain reaction (PCR) stop assays, and surface plasmon resonance (SPR) experiments. Moreover, both corroles 3 and 4 tend to induce the human telomeric sequence to form hybrid G-quadruplex structures, whereas corroles 8 and 9 are more inclined to induce the human telomeric sequence to form antiparallel G-quadruplex structures.

New Delhi metallo-β-lactamase-1 (NDM-1), an acquired class B carbapenemase, is a significant clinical threat due to its extended hydrolysis of β-lactams including carbapenems. In this study, we identified the first confirmed clinical isolate of Escherichia coli BJ01 harboring bla NDM-1 in China. The isolate is highly resistant to all tested antimicrobials except polymyxin. bla NDM-1, bla CTX-M-57, and bla TEM-1 were identified in the isolate. bla NDM-1 was transferable to E. coli EC600 and DH5α in both plasmid conjugation experiments and plasmid transformation tests. BJ01 was identified as a new sequence type, ST224, by multilocus sequence typing. Analysis of genetic environment shows complex transposon-like structures surrounding the bla NDM-1 gene. Genetic analysis revealed that the region flanking bla NDM-1 was very similar to previously identified NDM-positive Acinetobacter spp. isolated in China. The findings of this study raise attention to the emergence and spread of NDM-1-carrying Enterobacteriaceae in China.

2198 Al-Li alloy welds were performed by friction stir welding (FSW) to investigate the influence of the ratio of rotation speed to welding speed (v/n) on joint microstructure, microhardness, and tensile properties. Transmission electron microscopy (TEM) was used to reveal the precipitate type across the weld cross-section. Results show that v/n has a little impact on both macroscopic morphology and microstructure of joints. Dissolution of precipitates has occurred in the weld nugget (WN). The density of T 1 phase and its size in the WN decrease remarkably. Changes to the T 1 phase are linked to a significant reduction in microhardness across the weld. With increasing v/n the microhardness of the joints decreases. The value of v/n also has impact on the fracture mode of the joints as well as the elongation.