Construction of stable photo-Fenton system with efficient removal capability of ciprofloxacin by accelerating in-situ photoreduction of Fe3+ in MIL-100(Fe).

Well-dispersed MIL-100(Fe) nanoparticles were synthesized under mild conditions and used to construct a photo-Fenton system (VMH system) with the assistance of visible-light irradiation and hydrogen peroxide. In such a VMH system, the MIL-100(Fe) has a high specific surface area and provides numerous Fe3+ active sites, thus accelerating the reaction of Fe3+ with photo-generated electrons under visible-light irradiation and generates Fe2+, and then the acquired Fe2+ can activate H2O2 to generate ⋅OH, accompanying with the oxidation of Fe2+ to Fe3+. Hence, the in-situ recycling of Fe2+/Fe3+ promotes the generation of ·OH, thus making the VMH system exhibits promising photocatalytic activity. The removal rate of ciprofloxacin in the VMH system is as high as 95.2% within 120 min photo-Fenton reaction, which is about 26 times higher than that of the Visible light/MIL-100(Fe) system. Moreover, the VMH system also exhibits strong degradation ability to other typical antibiotics, such as tetracycline, norfloxacin and cephalexin, and maintains high cyclic stability, revealing great practical application potential in the purification of antibiotic wastewater.

Enhanced High-Temperature Wear Performance of H13 Steel through TiC Incorporation by Laser Metal Deposition.

High-temperature wear failure has been a major challenge to die parts. This work provides a comprehensive study on the high-temperature wear performance of a TiC/H13 composite coating prepared by laser metal deposition (LMD). The microstructures of wrought H13 samples, LMD-processed H13 and TiC/H13 samples were systematically investigated. The refined martensite size, the uniform distribution of TiC ceramic particles, as well as their bonding with the matrix endowed the fabricated composite coating with superior hardness. The LMD-prepared TiC/H13 composite coating material demonstrated outstanding wear resistance when compared with other counterparts, mainly due to the high thermal stability and the load-transferring effect triggered by the introduced TiC ceramic particles. The dominated wear mechanism transition from severe ploughing in the wrought H13 material to mild delamination in the TiC/H13 composite coating was confirmed. The present study is expected to shed light on high-temperature wear-resistant coating material design and applications within the highly demanding mould industry.

Structural Basis and Mechanism for Vindoline Dimers Interacting with α,ß-Tubulin.

Vinblastine and its derivatives used in clinics as antitumor drugs often cause drug resistance and some serious side effects; thus, it is necessary to study new vinblastine analogues with strong anticancer cytotoxicity and low toxicity. We designed a dimer molecule using two vindoline-bonded dimer vindoline (DVB) and studied its interaction with α,ß-tubulin through the double-sided adhesive mechanism to explore its anticancer cytotoxicity. In our work, DVB was docked into the interface between α-tubulin and ß-tubulin to construct a complex protein structure, and then it was simulated for 100 ns using the molecular dynamics technology to become a stable and refined complex protein structure. Based on such a refined structure, the quantum chemistry at the level of the MP2/6-31G(d,p) method was used to calculate the binding energies for DVB interacting with respective residues. By the obtained binding energies, the active site residues for interaction with DVB were found. Up to 20 active sites of residues within α,ß-tubulin interacting with DVB are labeled in ß-Asp179, ß-Glu207, ß-Tyr210, ß-Asp211, ß-Phe214, ß-Pro222, ß-Tyr224, and ß-Leu227 and α-Asn249, α-Arg308, α-Lys326, α-Asn329, α-Ala333, α-Thr334, α-Lys336, α-Lys338, α-Arg339, α-Ser340, α-Thr349, and α-Phe351. The total binding energy between DVB and α,ß-tubulin is about -251.0 kJ·mol-1. The sampling average force potential (PMF) method was further used to study the dissociation free energy (ΔG) along the separation trajectory of α,ß-tubulin under the presence of DVB based on the refined structure of DVB with α,ß-tubulin. Because of the presence of DVB within the interface between α- and ß-tubulin, ΔG is 252.3 kJ·mol-1. In contrast to the absence of DVB, the separation of pure ß-tubulin needs a free energy of 196.9 kJ·mol-1. The data show that the presence of DVB adds more 55.4 kJ·mol-1 of ΔG to hinder the normal separation of α,ß-tubulin. Compared to vinblastine existing, the free energy required for the separation of α,ß-tubulin is 220.5 kJ·mol-1. Vinblastine and DVB can both be considered through the same double-sided adhesive mechanism to give anticancer cytotoxicity. Because of the presence of DVB, a larger free energy is needed for the separation of α,ß-tubulin, which suggests that DVB should have stronger anticancer cytotoxicity than vinblastine and shows that DVB has a broad application prospect.