•Dual detection modes were realized for Hg2+ sensing.•Cytotoxicity of sulfur dots was evaluated.•Endocytosis mechanism concerning sulfur dots was established.•Cellular tracking of mercury ions was ...realized.
As the standard for heavy metal sensing systems increases, it becomes more important to find out new self-indicating materials as alternatives. The traditional design of optical probe contains receptor and fluorophore as two moieties. Here a novel sulfur quantum dot as the intrinsic fluorescent sensor has been established and the signal transduction involves interaction of mercury ions with sulfur atoms which belongs to the internal system of the fluorophore. Its analytical performances can be assessed by fluorometric and colorimetric titrations simultaneously and the detection limits for Hg2+ ions are determined to be 65 nM and 1.86 μM respectively. In the presence of sulfur dots, very low cytotoxicity has been verified in two cell lines (HeLa and K562) via both cell counting kit-8 method and flow cytometry. For the first time, four sorts of chemical inhibitors have been employed to clarify the endocytosis mechanism based on sulfur quantum dots. The collected results indicate that clathrin and lipid raft mediated endocytosis play as primary roles in the internalization processes. It has been found that sulfur dots are located in the cytoplasm with intense blue emissions and the cellular tracking of mercury ions has been realized.
Metallic Zn is considered as an ideal anode while its widespread use in rechargeable aqueous batteries still faces many challenges, mostly associated with the dendritic growth and corrosion of Zn and ...the side reactions. In this work, we demonstrate that a TiN protective coating layer with the preferential (200) orientation can effectively suppress both the Zn dendritic growth and side reactions; more interestingly, it can regulate the growth pattern of the byproduct (zinc hydroxide sulfate or ZHS) by inducing a lateral growth. As a result, reversible Zn plating/stripping over 2300 h at a practical current density of 1 mA cm–2 is achieved along with a nearly 100% Coulombic efficiency. This work not only establishes TiN (200) coatings as an effective Zn anode protective layer but also provides insights into the role of ZHS byproduct as well as strategies to inhibit side reaction and to regulate the growth pattern of ZHS.
Hierarchical Co3O4 porous nanowires （NWs） have been synthesized using a hydrothermal method followed by calcination. When employed as a cathode catalyst in non-aqueous Li-oxygen batteries, the Co3O4 ...NWs effectively improve both the round-trip efficiency and cycling stability, which can be attributed to the high catalytic activities of Co3O4 NWs for the oxygen reduction reaction and the oxygen evolution reaction during discharge and charge processes, respectively.
In this article, the molecular average polarizability α, the energy of the highest occupied molecular orbital E HOMO, the total thermal energy E thermal, and the total entropy S were used to ...correlate with glass transition temperature T g for 113 polymers. The quantum chemical descriptors obtained directly from polymer monomers can represent the essential factors that are governing the nature of glass transition in polymers. Stepwise multiple linear regression (MLR) analysis and back-propagation artificial neural network (ANN) were used to generate the model. The final optimum neural network with 4-4-2₂-1 structure produced a training set root mean square error (RMSE) of 11 K (R = 0.973) and a prediction set RMSE of 17 K (R = 0.955). The results show that the ANN model obtained in this paper is accurate in the prediction of T g values for polymers.
Series of biodegradable polyesters poly(butylene adipate) (PBA), poly(butylene succinate) (PBS), and poly(butylene adipate-co-butylene terephthalate) (PBAT) were synthesized successfully by melt ...polycondensation. The polyesters were characterized by Fourier transform infrared spectroscopy (FTIR), 1H-NMR, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC), respectively. The blends of poly(lactic acid) (PLA) and biodegradable polyester were prepared using a twin screw extruder. PBAT, PBS, or PBA can be homogenously dispersed in PLA matrix at a low content (5–20 wt%), yielding the blends with much higher elongation at break than homo-PLA. DSC analysis shows that the isothermal and nonisothermal crystallizabilities of PLA component are promoted in the presence of a small amount of PBAT.
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A new dicyanoisophorone-based derivative (ICM-S) with strong push-pull electron effect has been afforded and it exhibits red shift with distinct color change from pale yellow to deep ...yellow upon exposure to Hg2+. Moreover, an easily distinguishable fluorescence color change from green to red in the presence of Hg2+ under a UV lamp irradiation. Its in vitro responses to Hg2+ have been evaluated in 293 T cells and the effectiveness in zebrafish model has also been verified.
A wide variety of molecular probes have been developed for real-time analysis, but most of organic fluorophores possess small Stokes shifts and self-absorption or inner filter effect that could not be avoided. In this study, a new dicyanoisophorone-based derivative (E)-O-(4-(2-(3-(dicyanomethylene)-5,5-dimethylcyclohex-1-en-1-yl)vinyl)phenyl)diphenylphosphinothioate (λex=405 nm, λem=551 nm, denoted as ICM-S) with strong push-pull electron effect has been afforded and it exhibits red shift for absorption from 407 nm to 426 nm with distinct color change from pale yellow to deep yellow upon exposure to Hg2+. Moreover, an easily distinguishable fluorescence color change follows the route from green, yellow to red in the presence of Hg2+ over the range of 0−90 μmol/L (detection limit=137nmol/L) can be observed by the naked eye under a UV lamp irradiation. Chlorodiphenylphosphine and sublimed-sulfur are incorporated as responsive sites and P-O bond has been cleaved upon the addition of mercury ions. During the recognition process, such dicyanoisophorone dye (ICM-S) has been evolved to 2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene) malononitrile (ICM−OH). Clear evidences in the chemical processes can be identified via single crystal X-ray diffraction, spectroscopic analysis, photophysical studies and titration experiments. With the aim of exploring its potential in biological systems, its in vitro responses to Hg2+ have been evaluated in 293 T cells and the effectiveness in zebrafish model has also been verified.
Mechanical alloying technique and subsequent annealing were used to prepare the Ti49Zr26Ni25 quasicrystal. Composite materials of multi-walled carbon nanotubes (MWCNTs) doped Ti49Zr26Ni25 alloys were ...obtained via ball-milling to improve the hydrogen storage performance of Ti49Zr26Ni25. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to analyze the structural properties of the samples. The phase structures of the composite alloys were composed of icosahedral quasicrystal phase and Ti2Ni-type phase. Smaller alloy particles were obtained after doping MWCNTs. Moreover, a three-electrode battery system was carried out to test the electrochemical properties. The composites showed higher discharge capacity, stronger HRD, better cyclic stability and lower charge-transfer resistance than the original Ti49Zr26Ni25 alloy. In the composite electrodes, the optimal discharge capacity of 254.2 mAh/g and the highest capacity retention of 63.1% were achieved for 5 wt.% additive content of MWCNTs. The electro-catalytic function of MWCNTs, the reduction of particle size and raise of specific surface area for Ti49Zr26Ni25 alloy may provide larger electrochemically accessible area and rapid channel for hydrogen transportation, which are crucial for improving the electrochemical performance of the alloy.
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•Composites of Ti49Zr26Ni25 mixed with MWCNTs are prepared by ball-milling method.•The maximum discharge capacity is enhanced by doping with MWCNTs.•The cycling stability and HRD of the composite electrodes are improved.•The distinctive structure of MWCNTs may be favorable to the hydrogen transmission.
Ti45Zr38Ni17 quasicrystal ribbons were prepared by arc-melting and subsequent melt spinning technique. Composite materials of Ti45Zr38Ni17 mixed with different amounts of LiH were fabricated via ...mechanical ball-milling method. The phase structures of the final composite materials consist of the icosahedral quasicrystal phase (I-phase), face-centered cubic phase with a Ti2Ni type crystal, C14 Laves phase and LiH phase. The electrochemical measurements showed that the maximum discharge capacities for the composites were higher than those for the Ti45Zr38Ni17 alloy and reached a maximum (91.5 mAh/g) for 10 wt.% additive content of LiH. Furthermore, the cycling stability and high-rate dischargeability (HRD) of the composite electrodes were improved obviously. The capacity retention of Ti45Zr38Ni17 + 10 wt.% LiH enhanced to 88.1%, and the HRD increased from 75.2% to 88.6%. The improvement of electrochemical properties for the composites may be due to the reversible reaction of LiH in alkaline conditions, which can enhance the electrochemical activity of the alloy during the charging and discharging reactions. The results indicated that LiH was an effective material in improving the hydrogen storage property of the Ti45Zr38Ni17 alloy.
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•Composites of Ti45Zr38Ni17 mixed with LiH are prepared by ball-milling method.•The maximum discharge capacity is enhanced after doping with LiH.•The cycling stability and HRD of the composite electrodes are improved.•Electrochemical catalytic activity of LiH is favorable for transmission of hydrogen.
Study on the substituent effects of X and Y on NMR chemical shifts δ(H4,6), δ(C2), δ(C4,6), δ(C5), δ(C1′) and δ(C4’). Display omitted
•Forty-eight 2-(4-X phenyl)-5-Y pyrimidines with various ...substituents were synthesized.•1H NMR and 13C NMR spectra for each compound were determined.•Substituent effects on NMR chemical shifts were characterized by molecular descriptors.•QSPR models were built for NMR chemical shifts and the physical meaning of each model was discussed.•The results by QSPR models of this paper were compared with those predicted by CASCADE.
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