N-Heterocyclic Carbene Silver Complex Modified Polyacrylonitrile Fiber/MIL-101(Cr) Composite as Efficient Chiral Catalyst for Three-Component Coupling Reaction.

Complex asymmetric synthesis can be realized by the chiral induction of amino acids in nature. It is of great significance to design a new biomimetic catalytic system for asymmetric synthesis. In this context, we report the preparation and characterization of the composite of polyacrylonitrile fiber (PANF) and metal-organic framework to catalyze the chiral synthesis of propargylamines. A confined microenvironment is established with N-heterocyclic carbene (NHC) silver complex-supported PANF and D-proline-encapsulated MIL-101(Cr). This novel supported catalyst demonstrated high activity in addition to excellent stereoselectivity in the three-component reaction between alkynes, aldehydes, and amines (A3). The regeneration can be realized by adsorption of D-proline again when the stereoselectivity decreases after recycle uses. By regulating the confined microenvironment on the composite, the activity and selectivity of the catalytic system are improved with turnover numbers of up to 2800 and 98% ee. The biomimetic catalytic system to A3 coupling reaction is systematically studied, and the synergistic catalytic mechanism between NHC-Ag and D-proline in the confined microenvironment is revealed.

Utilization of a Mobile Multifunctional Workstation for Coronavirus Nasopharyngeal/Oropharyngeal Specimen Collection.

Objectives: This study aimed to explore the utilization of a mobile multifunctional workstation for COVID-19 sample collection. Methods: Twenty-four nurses and 150 individuals who took nucleic acid tests using mobile multifunctional workstations in Beijing Youan Hospital, Capital Medical University, from September to November 2020, were enrolled in the study as the observation group. As the control group, we included 36 nurses and 150 individuals who did not use the workstations from June to September 2020. We compared the two groups on (1) comfort of working environment, self-perceived security, the convenience of information system, operational process flexibility, pharyngeal acquisition visibility, and effectiveness of communication among nurses; and (2) self-perceived safety, waiting time, and overall satisfaction among individuals who took nucleic acid tests. Results: The satisfaction score of nurses in the observation group of nurses were significantly higher than those of the control group (OR = 17.297 95% CI:4.294, 69.673), as well as the convenience of the information system (OR = 6.250 95% CI: 1.775, 22.008), and communication effectiveness (OR = 5.588 95% CI: 1.590, 19.646). Among individuals who took nucleic acid tests, the overall satisfaction (P < 0.05) and self-perceived security (P < 0.05) had statistical differences between the observation group and the control group. Conclusions: The mobile multifunctional workstation for specimen collection could improve the comfort of the working environment, the convenience of information systems, and the effectiveness of communication among nurses.It can improve satisfaction and self-perceived security among people who took nucleic acid tests.

A selective diaminomaleonitrile-based dual channel emissive probe for Al3+ and its application in living cell imaging.

A selective diaminomaleonitrile-based fluorescent probe for Al3+(L) has been synthesized and characterized. The sensing behavior of L towards different metal ions was investigated by fluorescent spectra and competition experiment. The results showed that L exhibited a dual channel emission (λem 522 & 558 nm) with yellow fluorescence in the presence of Al3+ over other metal ions in EtOH solution. The probe L was bound to Al3+ in a 1:2 stoichiometric manner as supported by Job's plot analysis. The binding constant was 9.55 × 108 M-2 with the detection limit of 10.3 nM. The turn-on response was attributed to the inhibition of PET and CN isomerization after binding with Al3+ while the dual emissions were due to ESIPT and ICT processes. In addition, the application of L for imaging Al3+ in living Hela cells was achieved.

Visual detection of cyanide ion in aqueous medium by a new chromogenic azo-azomethine chemosensor.

A simple and new chromogenic azo-azomethine chemosensor N'-(5-((2,4-dichloro- phenyl) diazenyl)-2-hydroxylbenzylidene) picolinohydrazide (L) has been synthesized as an effective colorimetric sensor for cyanide ion. The sensing behavior of the probe L towards CN- over other anions was examined by naked-eye, UV-vis spectroscopy and NMR studies. L exhibited a selective sensing ability to CN- in DMSO/H2O(6:4, v:v) binary solution and DMSO/Tris(10 mM, pH = 7.1, 6:4, v:v) buffer solution by changing color from colorless to yellow. The detection limit was calculated to be 6.4 µM. The recognition mechanism was attributed to deprotonation process according to 1H NMR titration method. Moreover, test strips coated with L were easily fabricated with low cost and could be used to detect CN- in aqueous solution conveniently.

Optimization of Vacuum Microwave-Mediated Extraction of Syringoside and Oleuropein from Twigs of Syringa oblata.

A vacuum microwave-mediated method was used to extract syringoside and oleuropein from Syringa oblata twigs. The optimal extraction conditions were an ethanol volume fraction of 40%, a liquid-solid ratio of 17 mL/g, 1 h of soaking time, -0.08 MPa of vacuum, a microwave irradiation power of 524 W, and a microwave irradiation time of 8 min. Under optimal parameters, the maximum yields of syringoside (5.92 ± 0.24 mg/g) and oleuropein (4.02 ± 0.18 mg/g) were obtained. The proposed method is more efficient than conventional methods for extracting syringoside and oleuropein from Syringa oblata. Moreover, less energy and time were required. The results implied that vacuum microwave-mediated extraction is a suitable method for the extraction of thermosensitive glycosides such as syringoside and oleuropein.

Poly[aqua-[µ(3)-4-carb-oxy-2-(pyridin-4-yl)-1H-imidazole-5-carboxyl-ato-κN,O:N,O:N]nickel(II)].

The water-coordinated Ni(2+) cation in the title compound, [Ni(C(10)H(5)N(3)O(4))(H(2)O)](n), assumes an octa-hedral NiN(3)O(3) coord-ination mode and is N,O-chelated by two deprotonated 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarb-oxy-lic acid (HPyImDC(2-)) ligands, forming a layer structure extending in the bc plane. The chains are arranged along the b-axis direction, forming a layer structure extending in the bc plane. O-H⋯O hydrogen bonding between the layers results in the formation of a three-dimensional supra-molecular framework. The structure is isotypic with the Zn analogue [Li et al. (2009). Cryst. Growth Des.6, 3423-3431].