Latest ArticlesMg2+ in MgAl-layered double hydroxides nanoparticles was substituted with different divalent transition metal ions (MAl-LDHs, M:Mg2+, Cu2+, Ni2+, Co2+, and Mn2+) via a facile method to be used as antibacterial agents. The phase structural and morphological characterizations of MAl-LDHs were investigated by XRD, FTIR spectroscopy and TEM. The results have shown that all of MAl-LDHs had typical layered structures except MnAl-LDH which contained Mn3O4 phases. Particular morphology of MnAl-LDH with ellipsoids, spherical and rod-like structure and CuAl-LDH with rod-like shape existed. IC50 (the concentrations providing 50% antibacterial activity) values of CuAl-LDH, NiAl-LDH, CoAl-LDH, and MnAl-LDH in broth dilution tests were ~800-1500 μg/mL. Dosages of CuAl-LDH, CoAl-LDH, and MnAl-LDH with >10 mm inhibition zone in disk diffusion tests were ~150-300 μg/disk. Antibacterial mechanism of MAl-LDHs may be attributed to the synergistic factors including effected surroundings, surface interactions, morphology of particles, ROS and metal ions. The results indicate a facile method to synthesis LDHs based effective antibacterial agents with the potential application in the area of water treatment and antibacterial coating.
A novel amphiphilic cationic block copolymer polylysine-b-polyphenylalanine (PLL-b-PPhe) was synthesized and self-assembled into micelles in aqueous solution, then shielded with poly(glutamic acid) (marked as PG/PLL-b-PPhe) to codeliver gene and drug for combination cancer therapy. Here, doxorubicin (DOX) was selected to be loaded into PLL-b-PPhe micelles and the drug loading efficiency was 8.0%. The drug release studies revealed that the PLL-b-PPhe micelles were pH sensitive and the released DOX could reach to 53.0%, 65.0%, 72.0% at pH 7.4, 6.8 and 5.0, respectively. In order to reduce positive charge and cytotoxicity of PLL-b-PPhe micelles, PG was used as shelding, simultaneously condensed with Bcl2 siRNA to form gene carrier system. Compared with PEI, PG/PLL-b-PPhe had excellent gene transfection efficiency, especially when the molar ratio of PLL to PPhe was 30:60 and the mixed mass ratio of PLL-b-PPhe to gene was 5:1. More importantly, DOX and Bcl2 siRNA gene codelivery system displayed remarkable cytotoxicity against B16F10 cells. Confocal laser scanning microscopy (CLSM) and flow cytometry were used to characterize endocytosis of the codelivery system, and confirmed that both DOX and Bcl2 siRNA had been endocytosed into B16F10 cells. The above results indicated that gene and drug codelivery was a promising strategy in future cancer therapy.
Reusable palladium nanoparticles highly dispersed in porous and hydrophilic interpenetrating polymer networks (IPN), i.e., Pd@IPN hybrid gels, are employed for catalysis of Suzuki and Heck coupling reactions. Good yields are obtained with high turnover frequencies when the reactions are run with very low Pdloadings. The use of IPN gives better recyclability than that of crosslinked polyvinyl alcohol alone. The polymer networks allow the reactants to have easy access to the Pd metals. The catalysts combine high activity with the reusability offered by the heterogeneous system, without the need for strong coordination or chelating ligands.
As one of the most environmentally friendly photovoltaic (PV) conversion equipments, aqueousprocessed CdTe nanocrystal solar cells (NC SCs) have attracted great interest in recent years because of their excellent properties such as high charge-carrier mobility and broad absorption. However, two issues including interfacial recombination and leakage current seriously restrict their performance. In this paper, insulating polymer poly(vinyl pyrrolidone) (PVP) is introduced into CdTe NC SCs to solve the problems. The experimental results of transmission electron microscopy (TEM), atomic force microscopy (AFM) and dark current measurements, etc., demonstrate the leakage current is effectively suppressed by introducing PVP. Through further designing device structure, the reduction of interfacial recombination after introducing PVP is confirmed. By strategically taking the advantages of PVP properties (e.g., water solubility and thermostability), the power conversion efficiency of the devices with PVP is enhanced by almost 37% compared to pure CdTe devices. This work demonstrates an effective and low-cost method to fabricate NC SCs via aqueous route. Moreover, it also proves that appropriate content of insulating polymer is of beneficial in promoting the PV performance.
Recently, ZnO-based gas sensors have been successfully fabricated and widely studied for their excellent sensitivity and selectivity, especially in CO detection. However, detailed explorations of their mechanisms are rather limited. Herein, aiming at clarifying the sensing mechanism, we carried out density functional theory (DFT) calculations to track down the CO adsorption and oxidation on the ZnO (1010) and (1120) surfaces. The calculated results show that the lattice O of ZnO(1010) is more reactive than that of ZnO(1120) for CO oxidation. From the calculated energetics and structures, the main reaction product on both surfaces can be determined to be CO2 rather than carbonate. Moreover, the surface conductivity changes during the adsorption and reaction processes of CO were also studied. For both ZnO (1010) and (1120), the conductivity would increase upon CO adsorption and decrease following CO oxidation, in consistence with the reported experimental results. This work can help understand the origins of ZnO-based sensors' performances and the development of novel gas sensors with higher sensitivity and selectivity.
Herein, we report the first RhIII-catalyzed regioselective C8 arylation of quinoline N-oxides with commercially available arylboronic acids as coupling partners. This procedure is simple, and the reaction shows perfect regioselectivity, a broad substrate scope, and isolated yields of up to 92%. We demonstrate the utility of the reaction by using it for late-stage functionalization of a fungicide.
The compound[(CH3)2CH-C3H17N] [CoBr4] (1) based on quinuclidine derivatives was achieved by the solution synthetic method and characterized by elemental analysis, infrared spectroscopy, single-crystal X-ray structural analysis and dielectric measurement, respectively. Variable-temperature single-crystal X-ray diffraction suggested that the compound underwent the phase transition from the space group C2/c to Cc. The polarization curve was measured using the Sawyer-Tower circuit. The structural phase transitions of 1 was ascribed to the distortion of a[(CH3)2CH-C3H17N]2+ cation from this inorganic-organic hybrid material[(CH3)2CH-C3H17N] [CoBr4]. The strong change in dielectric anomalies makes compound 1 a suitable candidate for promising switchable dielectric materials. This work represents a feasible strategy thought for the targeted harvesting of low temperature ferroelectrics.
H2S can cause multiple diseases and poses a great threat to human health. However, the precise detection of extremely toxic H2S at room temperature is still a great challenge. Here, a facile solvent evaporation induced aggregating assembly (EIAA) method has been applied for the production of ordered mesoporous carbon (OMCs) in an acidic THF/H2O solution with high-molecular-weight poly(ethylene oxide)-b-polystyrene (PEO-b-PS) copolymers as the structure-directing agent, formaldehyde and resorcinol as carbon precursors. Along with the continuous evaporation of THF from the mixed solution, cylindrical micelles are formed in the solution and further assemble into highly ordered mesostructure. The obtained OMCs possesses a two-dimensional (2D) hexagonal mesostructure with uniform and large pore diameter (~19.2 nm), high surface area (599 m2/g), and large pore volume (0.92 cm3/g). When being used as the resonant cantilever gas sensor for room-temperature H2S detection, the OMCs has delivered not only a superior gas sensing performance with ultrafast response (14 s) and recovery (21 s) even at low concentration (2 ppm) but also an excellent selectivity toward H2S among various common interfering gases. Moreover, the limit of detection is better than 0.2 ppm, indicating its potential application in environmental monitoring and health protection.
Due to the diversity and feasibility of structural modification for organic molecules, organic-based redox flow batteries (ORFBs) have been widely investigated, especially in aqueous solution under neutral circumstance. In this work, a symmetric aqueous redox flow battery (SARFB) was rationally designed by employing a bipolar redox active molecule (N, N'-dimethyl-4, 4-bipyridinium diiodide, MVI2) as both cathode and anode materials and combining with an anion exchange membrane. For one MVI2 flow battery, MV2+/MV·+ and I-/I3- serve as the redox couples of anode and cathode, respectively. The MVI2 battery with a working voltage of 1.02 V exhibited a high voltage efficiency of 90.30% and energy efficiency of 89.44% after 450 cycles, and crossover problem was prohibited. The comparable conductivity of MVI2 water solution enabled to construct a battery even without using supporting electrolyte. Besides, the bipolar character of MVI2 battery with/without supporting electrolyte was investigated in the voltage range between -1.2 V and 1.2 V, showing excellent stable cycling stability during the polarity-reversal test.
Graphene is a two-dimensional nanomaterial with huge surface area, high carrier mobility and high mechanical strength. Because of its great potential in nanotechnology and environmental protection, it has attracted much attention in environmental and energy fields since its discovery in 2004. Although graphene is a star material, many reviews have introduced its use in terms of energy, the research progress in the field of environment, especially water pollution control, has been rarely reported. Here, we review exhaustively the research progress of graphene-based materials in environmental pollution remediation in the past ten years. Firstly, the advantages and classification of graphene were introduced. Secondly, the research progress and main achievements of graphene and its composites in the fields of photocatalytic degradation, pollutant adsorption and water treatment were emphatically described, and the mechanism of action in the above fields was summarized. Finally, we discuss the problems existing in the preparation and summarize the application of graphene in the environment.
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