RSC Advances

Gao, Yu; Li, Yazhen; Yang, Xiping; He, Fangfei; Huang, Jiamei; Jiang, Minghong; Zhou, Zaihui; Chen, Haijun

doi: 10.1039/c5ra12620gpmid: N/A

A novel fluorescence sensor was designed and synthesized for detecting Cu2+ with high sensitivity and selectivity. The sensor showed a large red-shift in UV-vis spectra and obvious decline of fluorescent intensity in fluorescence emission spectra upon the addition of Cu2+. Bio-imaging studies and flow cytometric analysis revealed that this sensor was cell-permeable and could be used for detection of changes of intracellular Cu2+, suggesting the suitability of this sensor for biological application. Cell cytotoxicity studies demonstrated it was capable of chelating excess Cu2+ in vitro to modulate the biological functions of Cu2+ with low cytotoxicity. Therefore, this compound could be a promising fluorescent sensor combining the abilities of either detection or modulation of the biological function of Cu2+ in biological conditions.

Kang, Baotao; Moon, Jong Hun; Lee, Jin Yong

doi: 10.1039/c5ra12188dpmid: N/A

In the present paper, density functional theory calculations have been implemented by using Dmol3 to study the electronic band structures of β-graphyne nanotubes (βGyNTs) and γ-graphyne nanotubes (γGyNTs). Our results found different GyNTs show diverse electronic band structures. All βGyNTs have quite small band gaps without any correlation with tube size. Meanwhile, γGyNTs, no matter zigzag or armchair, exhibit semiconductor characteristics with oscillatory band gap ranging from 0.48 eV to 1.20 eV. Furthermore, based on the variation of band gap, both zigzag and armchair γGyNTs can be divided into two subgroups: 2m and 2m + 1 where n is a positive integer, following the order of 2m + 1 > 2m.

Yang, Mengmeng; Yang, Yuanjun; Hong, Bin; Wang, Liangxin; Luo, Zhenlin; Li, Xiaoguang; Kang, Chaoyang; Li, Ming; Zong, Haitao; Gao, Chen

doi: 10.1039/c5ra13490kpmid: N/A

A series of high-quality vanadium dioxide (VO2) epitaxial thin films on (0001)-oriented sapphire substrates with various thicknesses were fabricated using radio frequency (RF) magnetron sputtering techniques. Structural analysis revealed that an out-of-plane tensile strain (∼+0.035%) in the thinner VO2 epitaxial films was induced by epitaxial lattice mismatch between the monoclinic VO2 films and Al2O3 substrates. However, an anomalous compressive strain (∼−0.32%) was accumulated along the out-of-plane direction in the thicker VO2 films. This result contradicts with the conventional epitaxial lattice-mismatch mechanism for strain formed in epitaxial films. We attribute this anomalous strain to the surface growth mode (island growth) in the thicker VO2 films, especially those sputtered from the metal target at low pressure. Furthermore, the metal–insulator transition (MIT) temperature shifted to lower temperature with decreasing thickness, which is attributed to modulation of the orbital occupancy through the epitaxial strain and growth-mode-induced strain in the VO2 epitaxial films. Moreover, the very large resistance change (on the order of magnitude ∼103) in the VO2/Al2O3 epitaxial heterostructures is promising for electrical switch applications.

Wen, Yu-qing; Meng, Hui-min; Shang, Wei

doi: 10.1039/c5ra12034apmid: N/A

A bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTESPT) self-assembled membrane (SAM) was prepared by self-assembly membrane technology on 6061 aluminum alloy. The SAM was evaluated using electrochemical techniques (potentiodynamic polarization and electrochemical impedance) in 3.5 wt% NaCl solution. In addition, molecular dynamics calculations showed a high binding energy between the self-assembled molecule and aluminum alloy surface. The formation of the self-assembled molecule was believed to be achieved by a chemical bond between the silicon oxide group and the metal surface atoms. Finally, X-ray photoelectron spectroscopy and scanning electron microscopy were carried out to confirm that BTESPT could form a membrane on 6061 aluminum alloy.

Li, Jingjing; Li, Xiaona; Li, Jianzhang; Gao, Qiang

doi: 10.1039/c5ra10003hpmid: N/A

This study was conducted to evaluate the potential of peanut meal (PM) to produce plywood adhesives via sodium dodecyl sulfate (SDS) and ethylene glycol diglycidyl ether (EGDE) modification. Five-ply plywood specimens were fabricated to measure water resistance. The physical properties, cross section, thermal behavior, and functional groups of the resultant adhesives were characterized in detail. The results showed using SDS and EGDE in the adhesive formulation greatly improved the water resistance of the resultant adhesive by 90% and met the interior use plywood requirements. This improvement was attributed to three reasons: (1) SDS broke the structure of the PM protein and exposed inner active groups, which reacted with EGDE and formed a dense network to improve the water resistance of the resultant adhesive; (2) EGDE decreased the adhesive viscosity and led to the adhesive easily penetrating into wood and forming more interlocks; (3) the adhesive with SDS and EGDE created a smooth surface of the cured adhesive to prevent moisture intrusion. Additionally, compared with the peanut meal-based control adhesives, the viscosity of the cured adhesive was reduced by 95.8% to 24 140 mPa s, which further demonstrated that peanut meal has favorable potential as an alternative adhesive material for plywood.

Cui, Fengxia; Liu, Huaqing; Zou, Zhongmei; Li, Hao

doi: 10.1039/c5ra12650apmid: N/A

Water deprivation can occur in isolated conditions by a natural disaster or under normal living conditions. However, the mechanism underlying response or adaption to water deprivation in mammals is not fully understood. This study was undertaken to unravel this mechanism. Male C57BL/6J mice were treated without or with water deprivation for four time periods (i.e., 1, 2, 3, and 4 days) before sacrifice. In four days of trial, no mice with or without drinking water experienced any mortality. Body weight, serum total protein, albumin, and trans-aminase activity were determined at 24 h intervals for 96 h. During dehydration, the mice's body weight decreased consistently. Moreover, a non-biased proton nuclear magnetic resonance (1H NMR)-based metabonomics strategy was performed to evaluate the effects of water deprivation on the responses of systemic hepatic metabolites in male C57BL/6J mice during a 96 h period. Water deprivation stress caused metabolic disturbance and changes in hepatic metabolites that are involved in the metabolisms of carbohydrates, lipids and amino acids. Under water deprivation stress, lactate and 3-hydroxybutylate might be the main energy sources. Increased taurine and branched chain amino acids (BCAAs) might confer tolerance and adaptability to mice under dehydration stress. Moreover, the increased free fatty acids (FFAs) caused by water deprivation probably contributed to counteracting dehydration related osmolality fluctuations. These results also reveal that the metabonomics strategy is a powerful tool to gain insight into the molecular mechanism of cellular response to environmental stresses.

Kraft, Vadim; Weber, Waldemar; Grützke, Martin; Winter, Martin; Nowak, Sascha

doi: 10.1039/c5ra16679apmid: N/A

In this work, the thermal decomposition of a lithium ion battery electrolyte (1 M LiPF6 in ethylene carbonate/ethyl methyl carbonate, 50/50 wt%) with a focus on the formation of organophosphates was systematically studied. The quantification of non-ionic dimethyl fluorophosphate and diethyl fluorophosphate was performed with synthesized standards by gas chromatography-mass spectrometry. Due to absence of commercially available or synthesized standards for the monitoring of ionic methyl fluorophosphate, ethyl fluorophosphate and ethylene phosphate a method working with ion chromatography-electrospray ionization-mass spectrometry was developed, where dibutyl phosphate was used as an internal standard. In addition, an ion chromatography conductivity detection method with short analysis time for simultaneous determination and quantification of F−, PF6− and BF4− was developed. The formation and degradation of analytes was studied to show the dependence of different temperatures, electrolyte volumes and separator materials. The thermal aging experiments were carried out in gas-tight aluminum vials at 80 °C for three weeks. After the storage time, the samples were diluted with the appropriate analysis solvents and investigated with gas chromatography-mass spectrometry, ion chromatography and ion chromatography-electrospray ionization-mass spectrometry. Finally, the thermal degradation of the electrolyte at 85 °C after five days in aluminum and glass vials was studied.

Deng, Weijun; Chen, Donghui; Hu, Jing; Chen, Liang

doi: 10.1039/c5ra15602epmid: N/A

We report a general and green approach to synthesize monodisperse ceria hollow spheres with tunable shell structure. After ceria precursor is coated on monodisperse poly(styrene-co-acrylic acid) spheres via a sol–gel method, ceria hollow spheres are successfully fabricated by calcination. The as-obtained hollow spheres exhibit enhanced photocatalytic activity under visible light. Our present work could not only provide a useful direction for the scale-up fabrication of other metallic oxide hollow spheres with tunable shell structure, but also open a new doorway to ceria based photocatalyst synthesis in an aqueous phase.

Li, Shanshan; Su, Zhi; Wang, Xinyu

doi: 10.1039/c5ra11005jpmid: N/A

A series of (1 − x)LiMnPO4·xLi3V2(PO4)3/C (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) composite nanoparticles are synthesized as cathode materials for lithium-ion batteries by the sol–gel method, using N,N-dimethyl formamide as a dispersing agent. The structure and morphology of the as-prepared materials are analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The materials exhibit good crystallinity and a grain size of about 20–100 nm. The 0.5LiMnPO4·0.5Li3V2(PO4)3/C composite delivers the best initial specific discharge capacity of 150.5 mA h g−1 at 0.05C in the voltage range of 2.5–4.4 V, and it exhibits excellent reversible capacities of 150.5, 135.1, 127.0, 122.5 and 115.7 mA h g−1 at charge–discharge rates of 0.05, 0.1, 0.2, 0.5, and 1C, respectively. Finally, 0.5LiMnPO4·0.5Li3V2(PO4)3/C retained 142.9 mA h g−1 (95%) of the initial specific discharge capacity after 50 cycles, demonstrating excellent cyclability. Compared with the LiMnPO4/C, its rate capability and cycle performance are both remarkably improved.

Zhou, Cuifeng; Du, Xusheng; Liu, Hongwei; Ringer, Simon P.; Liu, Zongwen

doi: 10.1039/c5ra13373dpmid: N/A

A novel Pt/CNT catalyst with a hierarchical structure was prepared. The effect of different morphologies of CNT supports on the catalyst microstructure and catalytic performance was studied. TEM tomography was used to analyse the real microstructure of the catalysts, including both the morphology of flower-like Pt clusters themselves and their distribution on the CNTs. The results revealed that Pt flowers were composed of nanorods, which dispersed in both the inner and outer tube surface of CNTs with larger inner tube diameter (TKCNTs). Comparing with the conventional Pt/CNT catalyst where Pt flowers only dispersed on the outer tube surface, the present Pt/TKCNT catalyst with the novel structure exhibited higher activity (enhanced to be ∼1.5 times higher current density) and better catalytic stability for methanol oxidation. Moreover, it displays ∼2 times higher activity for methanol electro-oxidation than that of CB supported Pt nanorod clusters. The results indicate that the catalytic performance of the Pt nanorods supported on different carbon supports depends on both carbon morphology and the distribution of the metal catalyst on the supports. The improved catalytic performance of the Pt/TKCNT catalyst with the novel hierarchical structure could be attributed to the confinement effect of TKCNTs.