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Molecular shuttles are typical molecular machines that could be applied in various fields. The motion modes of wheel components in rotaxanes could be strategically modulated by external stimuli, such as pH, ions, solvent, light, and so on. Light is particularly attractive because it is harmless and can be operated in a remote mode and usually no byproducts are formed. Over the past decade, many examples of light-driven molecular shuttles are emerging. Accordingly, this review summarizes the recent research progress of light-driven molecular shuttles. First, the light-driven mechanisms of molecular motions with different functional groups are discussed in detail, which show how to drive photoresponsive or non-photoresponsive molecular shuttles. Subsequently, the practical applications of molecular shuttles in different fields, such as optical information storage, catalysis for organic reactions, drug delivery, and so on, are demonstrated. Finally, the future development of light-driven molecular shuttle is briefly prospected.

In this article, the T15M (belonging to a kind of high speed steel powder) composite coating with different Ti content was prepared by laser cladding technology (LCT). The microstructure and properties of the samples were investigated by scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), automatic micro hardness tester and multifunctional friction and wear testing machine. The results show that the microstructure of the T15M composite coating is mainly composed of martensite, austenite and carbides which mainly distribute on the original austenite grain boundaries. With the increase of titanium element, the shape of carbides become more spherical and the carbides on the grain boundaries change from continuous to discontinuous which attributes to the destruction of carbon concentration balance at the interface. In contrast to the T15M composite coating without adding titanium, the carbides distribution in the coating are more uniform relying on preferential homogeneous nucleation of titanium compounds in solidification. By hardness test, it can be discovered that the addition of titanium to T15M composite coating has no significant effect on the average hardness, but the fluctuation range of the microhardness value decreases. After the sliding wear test, both the coefficient of friction and the mass loss after wear are reduced with the addition of titanium.

Low-cost and environmentally friendly mediators could facilitate the application of laccase (EC 1.10.3.2) in variant biotechnological processes. Acetylacetone (AA) represents an inexpensive and low toxic small molecular diketone that has been proven as an effective mediator for laccase in free radical polymerization. However, the potential of AA as a mediator for laccase in pollutant detoxification and/or degradation is still unknown. In this work, the roles of AA in laccase-induced polymerization and transformation were investigated. AA was demonstrated to be a highly efficient mediator in the laccase-induced grafting copolymerization of acrylamide and chitosan. The efficacy of AA in the laccase-induced decoloration of malachite green (MG) was compared with that of the widely used 1-hydroxybenzotriazole (HBT). The laccase-AA system had the highest turnover number (TON, 39.1 μmol/U), followed by the laccase-only system (28.5 μmol/U), while the TON of the laccase-HBT system was the lowest (14.9 μmol/U). The pseudo-first-order transformation rate constant (k 1) of MG in the laccase-AA system was up to 0.283 h−1 under the given conditions, while the k 1 of AA caused by laccase was only 0.008 h−1. In the five-cycle run, the concentration of AA remained stable. The larger TON of the laccase-AA system and the stability of AA in the cycling runs demonstrate that AA was more recyclable than HBT in the LMS, leading to a prolonged serving life of laccase. These results suggest that AA might be a potential redox mediator for laccase.

Dose distribution was calculated and analyzed on the basis of 16-bit computed tomography (CT) images in order to investigate the effect of scanning conditions on CT for metal implants. Stainless steel and titanium rods were inserted into a phantom, and CT images were obtained by scanning the phantom under various scanning conditions: i) Fixed tube current of 230 mA and tube voltages of 100, 120, and 140 kV; and ii) fixed tube voltage of 120 kV and tube currents of 180, 230, and 280 mA. The CT value of the metal rod was examined and corrected. In a Varian treatment planning system, a treatment plan was designed on the basis of the CT images obtained under the set scanning conditions. The dose distributions in the phantom were then calculated and compared. The CT value of the metal area slightly changed upon tube current alteration. The dose distribution in the phantom was also similar. The maximum CT values of the stainless steel rod were 14,568, 14,127 and 13,295 HU when the tube voltages were modified to 100, 120, and 140 kV, respectively. The corresponding CT values of the titanium rod were 9,420, 8,140 and 7,310 HU. The dose distribution of the radiotherapy plan changed significantly as the tube voltage varied. Compared with the reference dose, the respective maximum dose differences of the stainless steel and titanium rods in the phantom were 5.70, and 6.62% when the tube voltage varied. The changes in tube currents resulted in a maximum dose error of

In this study, a combined method based on cold extrusion and cold drawing was used to fabricate pure Mg mini-tubes. Their mechanical properties and corrosion behavior in simulated body fluid were systematically investigated. The results demonstrated the as-drawn pure Mg tube exhibited superior strengths with yield strength and ultimate tensile strength of 146.9 ± 5.3 MPa and 187.4 ± 7.4 MPa, respectively. Moreover, the as-drawn pure Mg tube also revealed relatively good corrosion resistance. After soaking in SBF for 144 h, the average corrosion rate of the pure Mg tube is 0.36 ± 0.03 mm y−1. The refined microstructure and strong basal texture induced by severe plastic deformation account for the improvement of corrosion resistance.

A mu-oxo diiron(III) complex [{Fe(pbba)Cl}(2)(mu-O)]Cl-2 (1, pbba = N-pyridylmethyl-N,N-bis(4-methylbenzimidazol-2-yl)amine) bearing multi-imidazolyl motifs was synthesized and characterized by X-r ...

Laccase is a green biocatalyst. It works with molecular oxygen and produces water as the only by-product. However, its practical application is far less than satisfactory due to the low stability/poor reusability of free laccase and the potential secondary pollution caused by dissolved mediators. To address those bottlenecks in laccase-based catalysis, a novel biocatalyst (Immo-LMS) was fabricated by simultaneously immobilizing both laccase and a mediator (acetylacetone, abbreviated as AA) into a hydrogel through the laccase-AA initiated polymerization. This self-initiated immobilization process avoided the forced conformational change of laccase in the passive embedding to pre-existing carriers. Resulting from the effective cooperation of laccase and AA, the Immo-LMS had the highest substrate conversion quantity to malachite green, followed by the sole immobilized laccase and the immobilized laccase with an external mediator. Besides the improved activity, the Immo-LMS showed enhanced stability. The good performance of the Immo-LMS suggests that the co-immobilization of laccase and mediator through the self-initiated one-pot process was a promising strategy for the immobilization of laccase, which is expected to be helpful to cut down the running cost as well as the potential toxicity that come from mediators in the practical application of laccase.

A monoruthenium(II) complex of the benzimidazolyl ligand and its deprotonated counterpart were prepared and structurally characterized. The reversible protonation/deprotonation process of the ancillary ligand switches the redox potential of the ruthenium(II) core from 0.69 to 0.26 V vs. Ag/AgNO3. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Complexes [Fe(Hpbi)(3)](ClO4)(2) (1) and [Fe(Hpbi)(3)](SbF6)(2) (2) (Hpbi = 2-(2-pyridyl)benzimidazole) were prepared by a modified method and characterized by IR, H-1 and C-13 NMR, mass spectrometry, electron paramagnetic resonance spectra and elemental analysis. The catalytic activities of 1 and 2 were evaluated for the oxidation of cyclohexene, cyclohexane, ethylbenzene and adamantane with tert-butylhydroperoxide or H2O2 as oxidant, and the results were compared with the properties of their analogue [Fe(bpy)(3)](SbF6)(2) (3). Complexes 1 and 2 both afforded the ketonization product for the oxidation of ethylbenzene and the hydroxylation product for adamantane.

A highly stable and efficient biocatalyst was fabricated by encapsulating Trametes versicolor laccase within a chitosan grafted polyacrylamide hydrogel (denoted as Lac-PAM-CTS). Scanning electron microscopy and nitrogen adsorption–desorption tests demonstrated that channels of diameter of 10–20 μm were regularly distributed throughout the sponge-like Lac-PAM-CTS. Besides, there were massive mesopores and macropores in the lamellar walls of the hydrogel. Such a network structure reduced the diffusion resistance of the hydrogel to the target substrates. The recovered activity of the obtained Lac-PAM-CTS was 40.8%. As compared to free laccase, the Lac-PAM-CTS showed enhanced thermal and chemical stability. The positive surface charge of the Lac-PAM-CTS endowed it with a pre-enrichment effect in the treatment of anionic dyes. In a continuous six-cycle batch decoloration of Malachite Green, the Lac-PAM-CTS showed much better durability than the free laccase. The results here suggest that sponge-like hydrogel is a good supporting matrix for laccase.

Lead-magnesium-niobate relaxor ferroelectric ceramics with a high dielectric constant and low sintering temperature for multilayer capacitors have been studied. PMN-PT-PCW and PMN-PT+excess PbO+excess MgO with normal, chemically pure raw materials processed by the direct formation of oxides (mixed-oxides procedure) were sintered at 860-960 degrees C. Values of epsilon max from 13000 to 18500 (at 1 kHz) and good aging characteristics were obtained. By means of X-ray diffraction analysis, it was found that the amount of pyrochlore phase is less than 2-3% in both the calcined powder and the samples. The dielectric constant of PMN-based ceramics was found to increase with excess MgO and excess PbO. A dense uniform microstructure was obtained at low firing temperatures. The selected-area diffraction pattern shows a ratio of niobium to magnesium of 1:1. >