Preparation and chromatographic performance of chiral peptide-based stationary phases for enantiomeric separation.

This study presents the development of three new chiral stationary phases. They are based on silica modified with peptides containing phenylalanine and proline. Successful analyses and characterizations were conducted using Fourier transform infrared spectra, elemental analysis, and thermogravimetric analysis. After this, the enantioselective performance of the three chiral peptide-based columns was evaluated. The evaluation used 11 racemic compounds under normal-phase high performance liquid chromatography mode. Optimized enantiomeric separation conditions were established. Under these conditions, the enantiomers of flurbiprofen and naproxen were successfully separated on CSP-1 column: the separation factor of these was 1.27 and 1.21, respectively. In addition, the reproducibility of the CSP-1 column was also investigated. The results of the investigation illustrated that the stationary phases have good reproducibility (RSD = 0.73%, n = 5).

Design, synthesis and evaluation of 2-(2-oxoethyl)pyrimidine-5-carboxamide derivatives as acetylcholinesterase inhibitors.

A novel series of 2-(2- oxoethyl)pyrimidine-5-carboxamide derivatives were designed, synthesized and evaluated as acetylcholinesterase inhibitors (AChEIs) for the treatment of Alzheimer's disease (AD). Biological activity results demonstrated that compound 10q showed the best inhibitory activity against AChE (IC50 = 0.88 ± 0.78 µM), which was better than that of Huperzine-A, and its inhibitory effect on BuChE was weak (IC50 = 10.0 ± 1.30 µM), which indicated that compound 10q was a dominant AChE inhibitor. In addition, the result of molecular docking study displayed that 10q could simultaneously bind to CAS and PAS sites of AChE, which was consistent with the mixed inhibition mode shown by the enzymatic kinetics study of 10q. Furthermore, the molecular properties of the target compounds were predicted online using the molinspiration server and pkCSM, The results exhibited that compound 10q had drug-like properties that satisfied the Lipinski's rule of five. Based on the bioactivity and molecular properties, compound 10q for further development was valuable.

Highly conductive VC embedded in carbon matrix as effective trapper and catalyst for Li-S batteries.

Vanadium carbide embedded in a nitrogen-doped carbon matrix (VC@NCM) is synthesized as a 3D freestanding sulfur host. Owing to the high electrical conductivity (1.6 × 104 S cm-1) of VC and strong chemisorption and catalytic effect on sulfur species, Li-S batteries with VC@NCM deliver enhanced redox kinetics with ultralow capacity decay of 0.01% per cycle after 1000 cycles at 1C. This work identifies the effect of strong chemisorption and high electrical conductivity on high S utilization and cycle stability in Li-S batteries.

A Full Li-S Battery with Ultralow Excessive Li Enabled via Lithiophilic and Sulfilic W2 C Modulation.

The practical application of Li-S batteries demands low cell balance (Licapacity /Scapacity ), which involves uniform Li growth, restrained shuttle effect, and fast redox reaction kinetics of S species simultaneously. Herein, with the aid of W2 C nanocrystals, a freestanding 3D current collector is applied as both Li and S hosts owing to its lithiophilic and sulfilic property. On the one hand, the highly conductive W2 C can reduce Li nucleation overpotentials, thus guiding uniform Li nucleation and deposition to suppress Li dendrite growth. On the other hand, the polar W2 C with catalytic effect can enhance the chemisorption affinity to lithium polysulfides (LiPSs) and guarantee fast redox kinetics to restrain S species in cathode region and promote the utilization of S. Surprisingly, a full Li-S battery with ultralow cell balance of 1.5:1 and high sulfur loading of 6.06 mg cm-2 shows obvious redox plateaus of S and maintains high reversible specific capacity of 1020 mAh g-1 (6.2 mAh cm-2 ) after 200 cycles. This work may shed new sights on the facile design of full Li-S battery with low excessive Li supply.

Conductive FeOOH as Multifunctional Interlayer for Superior Lithium-Sulfur Batteries.

The commercial course of Li-S batteries (LSBs) is impeded by several severe problems, such as low electrical conductivity of S, Li2 S2 , and Li2 S, considerable volume variation up to 80% during multiphase transformation and severe intermediation lithium polysulfides (LiPSs) shuttle effect. To solve above problems, conductive FeOOH interlayer is designed as an effective trapper and catalyst to accelerate the conversion of LiPSs in LSBs. FeOOH nanorod is effectively affinitive to S that Fe atoms act as Lewis acid sites to capture LiPSs via strong chemical anchoring capability and dispersion interaction. The excellent electrocatalytic effect enables that reduced charging potential barrier and enhanced electron/ion transport is realized on the FeOOH interlayer to promote LiPSs conversion. Significantly, Li2 S oxidation process is improved on the FeOOH interlayer determined as a combination of reduced Li2 S decomposition energy barrier and enhanced Li-ion transport. Therefore, the multifunctional FeOOH interlayer with conductive and catalytic features show strong chemisorption with LiPSs and accelerated LiPSs redox kinetics. As a result, LSBs with FeOOH interlayer displays high discharge capacity of 1449 mAh g-1 at 0.05 C and low capacity decay of 0.05% per cycle at 1 C, as well as excellent rate capability (449 mAh g-1 at 2 C).

Lotus Root-Like Nitrogen-Doped Carbon Nanofiber Structure Assembled with VN Catalysts as a Multifunctional Host for Superior Lithium-Sulfur Batteries.

Lithium-sulfur batteries (LSBs) are regarded as one of the most promising energy-recycling storage systems due to their high energy density (up to 2600 Wh kg-1), high theoretical specific capacity (as much as 1672 mAh g-1), environmental friendliness, and low cost. Originating from the complicated redox of lithium polysulfide intermediates, Li-S batteries suffer from several problems, restricting their application and commercialization. Such problems include the shuttle effect of polysulfides (Li2Sx (2 < x ≤ 8)), low electronic conductivity of S/Li2S/Li2S2, and large volumetric expansion of S upon lithiation. In this study, a lotus root-like nitrogen-doped carbon nanofiber (NCNF) structure, assembled with vanadium nitride (VN) catalysts, was fabricated as a 3D freestanding current collector for high performance LSBs. The lotus root-like NCNF structure, which had a multichannel porous nanostructure, was able to provide excellent (ionically/electronically) conductive networks, which promoted ion transport and physical confinement of lithium polysulfides. Further, the structure provided good electrolyte penetration, thereby enhancing the interface contact with active S. VN, with its narrow resolved band gap, showed high electrical conductivity, high catalytic effect and polar chemical adsorption of lithium polysulfides, which is ideal for accelerating the reversible redox kinetics of intermediate polysulfides to improve the utilization of S. Tests showed that the VN-decorated multichannel porous carbon nanofiber structure retained a high specific capacity of 1325 mAh g-1 after 100 cycles at 0.1 C, with a low capacity decay of 0.05% per cycle, and demonstrated excellent rate capability.

Synthesis and Investigation of CuGeO3 Nanowires as Anode Materials for Advanced Sodium-Ion Batteries.

Germanium is considered as a potential anode material for sodium-ion batteries due to its fascinating theoretical specific capacity. However, its poor cyclability resulted from the sluggish kinetics and large volume change during repeated charge/discharge poses major threats for its further development. One solution is using its ternary compound as an alternative to improve the cycling stability. Here, high-purity CuGeO3 nanowires were prepared via a facile hydrothermal method, and their sodium storage performances were firstly explored. The as-obtained CuGeO3 delivered an initial charge capacity of 306.7 mAh g-1 along with favorable cycling performance, displaying great promise as a potential anode material for sodium ion batteries.

Flower-like Cu2SnS3 Nanostructure Materials with High Crystallinity for Sodium Storage.

In this study, ternary Cu2SnS3 (CTS) nanostructure materials with high crystallinity were successfully prepared via a facile solvothermal method, which was followed by high-temperature treatment. The morphology of the as-synthesized samples is uniform flower-like spheres, with these spheres consisting of hierarchical nanosheets and possessing network features. Sodium storage measurements demonstrate that the annealed CTS electrodes have high initial reversible capacity (447.7 mAh·g−1 at a current density of 100 mA·g−1), good capacity retention (200.6 mAh·g−1 after 50 cycles at a current density of 100 mA·g−1) and considerable rate capability because of their high crystallinity and unique morphology. Such good performances indicate that the high crystallinity CTS is a promising anode material for sodium ion batteries.

Toxic effects of different types of zinc oxide nanoparticles on algae, plants, invertebrates, vertebrates and microorganisms.

Concerns about the potential environmental risks of zinc oxide nanoparticles (ZnO NPs) are becoming an important issue because of their rapid growth in different fields. ZnO NPs are inevitably released in the environment during the production, transport, use and disposal process. Therefore, it is necessary to understand their toxicities and mode of actions. This review summarizes the toxic effects of ZnO NPs with different properties and exposed conditions on different species. The mechanisms of ZnO NPs on living organisms could be mainly attributed to one or more of the following aspects: the physical damage of direct contact, the dissolved zinc ions and the ROS-mediated mechanism. This paper systematically reviews the toxic effects of ZnO NPs on organisms and puts forward the existing problems, which are helpful for the safe and efficient use of ZnO NPs, providing the basis for further study of the toxic effects of ZnO NPs and establishing a comprehensive and safe evaluation system.