Opening Band Gap of Graphene by Chemical Doping: a First Principles Study

Single atom chemically doped graphene has been theoretically studied by density functional theory. The largest band gap, 0.62 eV, appears in arsenic atom doped graphene, then 0.60 eV comes by the tin atom, whose deformations can neither be ignored. It is also found that oxygen and iron single atom embedded graphene can open band gap by 0.52 and 0.54 eV, respectively. Moreover, doping O atom shows little distortion and high stability by charge redistribution. The band gap of Fe doped graphene is opened by orbital hybridization. The other heteroatom doped results are a little inferior to them.     

UV-Vis Spectrum and the Third-order Nonlinear Optical Properties of the Chiral Camphorderived β-diketonate Platinum Complexes

UV-Vis spectrum and the third-order nonlinear optical properties of the chiral camphor-derived β-diketonate have been studied at the B3LYP/6-31G* level. The results showed that the introduction of electron-drawing group-CF3 and-C3F7 on β-diketonate made the strongest absorption peak red-shift and the lowest energy absorption blue-shied. Introduction of-OC2H5 on the benzene or pyridine ring made the lowest energy absorption blue-shift. When the-C2H3 was introduced on the benzene or pyridine ring, the lowest energy absorption was red-shifted. Introduction of electron-donating group on β-diketonate can enlarge their nonlinear optical properties. On the contrary, the introduction of electron-drawing group dropped it down.     

Conductometric and fluorescence probe investigations of molecular interactions between dodecyltrimethylammonium bromide and dipeptides

The effect of five dipeptides (glycylglycine, glycyl-l-valine, glycyl-l-leucine, glycyl-l-glutamine, and l-alanyl-l-glutamine) on the micellar properties of catonic surfactant dodecyltrimethylammonium bromide (DTAB) has been investigated by electrical conductivity and fluorescence spectroscopy. From the conductivity data, the critical micellar concentration (c _cmc), counterion binding constant (β), and thermodynamic parameters of micellization (ΔG _m ^o , ΔH _m ^o and ΔS _m ^o ) have been calculated. The effect of dipeptides on the micellar properties of DTAB depends upon their nature and concentration as well as on temperature and has been used to study the interactions present in the micellar systems. Enthalpy–entropy compensation effect has also been observed. The pyrene fluorescence spectra were used as an index for the estimation of micropolarity of micellar produced by the interaction of DTAB with dipeptides and the aggregation behavior of DTAB. Comparison on the interactions between different types of surfactants and dipeptide showed that the order of the strength for these interactions is TX-100?相似文献   

Catalytic epoxidation of alkenes over supported manganese oxide with hydrogen peroxide: effect of supports and manganese loading

Manganese oxides supported on γ-Al₂O₃, amorphous SiO₂, MCM-41, and TiO₂ prepared by an impregnation method were used as heterogeneous catalysts for epoxidation of alkenes with 30 % H₂O₂ in the presence of NaHCO₃ aqueous solution. The effect of support and manganese loading on their activity was studied. The 1.3-MnO _x /γ-Al₂O₃ exhibited superior epoxidazing activity of styrene, compared with other supported MnO _x . Hydrogen temperature-programmed reduction, UV–vis and ESR analyses suggested that Mn²⁺ (catalytic activity species) dominated in 1.3 % MnO _x /γ-Al₂O₃ due to a strong interaction between MnO _x and γ-Al₂O₃. Recycling studies showed the catalyst was a heterogeneous one and retained its activity after recycling four times.     

1-(2-苯并噻唑)-3-(3,5-二溴吡啶)-三氮烯的合成及其与铜(Ⅱ)的荧光反应

报道了1-(2-苯并噻唑)-3-(3,5-二溴吡啶)三氮烯(BTDPT)的合成及其与Cu(Ⅱ)的荧光反应研究。在pH 9.16的Na2B4O7-NaOH缓冲溶液中,该试剂与Cu(Ⅱ)形成2:1的稳定络合物,体系的激发和发射波长分别为359和401 nm。Cu质量浓度在0.5~80.0μg/L范围内与△F呈良好的线性关系,其线性回归方程为:ΔF=-0.178+0.209ρ(μg/L),相关系数r=0.9956,检出限为0.2μg/L,用于测定环境水中痕量Cu,结果与原子吸收光谱法相符。样品6次测定值相对标准偏差小于5%,加标回收率为98.5%~103.0%。     

白花败酱矿物质元素分析与利用

目的对野生白花败酱与栽培白花败酱8种矿物质元素进行了测定、分析与利用。方法采用火焰原子吸收分光光度法。结果白花败酱的嫩茎叶含有丰富的K、Ca、Na、Mg常量元素和Fe、Mn、Cu、Zn微量元素,栽培种的Mn含量是野生种的4倍多。结论白花败酱可作蔬菜食用,同时对土壤中的Mn有富集能力。     

基于丙二酰胺的不对称双子表面活性剂的合成及其乳化性能

将二(3-二甲氨基丙基)丙二酰胺分别与溴代十六烷和溴代十四烷反应,生成的季铵盐化产物经丙酮-乙腈重结晶,得到含丙二酰胺基的不对称阳离子双子(Gemini)表面活性剂(命名为16-9-14),总收率为45.9%(以溴代十六烷计);利用红外光谱和核磁共振谱表征了合成产物的结构,采用电导法测定了其临界胶束浓度(CMC),采用滴体积法测定了其临界张力(γCMC),进而初步探讨了其发泡沫性能和乳化性能.结果表明,合成的Gemini表面活性剂的CMC为1.57×10-4 mol/L,γCMC为38.45mN/m;其发泡性能和乳化性能优于相应的单子表面活性剂.     

羟基磷灰石/聚乙烯醇/壳聚糖水凝胶在模拟体液中的力学性能

从仿生学角度出发,将自制的人工角膜支架材料羟基磷灰石/聚乙烯醇/壳聚糖(n-HA/PVA/CS)浸泡在模拟体液中,对材料的含水率及力学性能进行了测试,并利用扫描电镜、X射线衍射仪、电感耦合等离子体原子发射光谱仪及热重分析仪研究了材料在模拟体液中的形貌、晶体结构、元素组成及热稳定性.结果表明,在模拟体液中,n-HA/PVA/CS复合水凝胶的含水率为80%~86%,具有较高的拉伸强度,能承受正常眼压,且热稳定性较好.在浸泡后期,n-HA/CS/PVA复合材料对Ca2+的吸附和释放达到动态平衡;而其表面含有微量的纳米羟基磷灰石沉积,有利于纤维细胞的长入.     

π-Interactions between Cyclic Carbocations and Aromatics Cause Zeolite Deactivation in Methanol-to-Hydrocarbon Conversion

The understanding of catalyst deactivation represents one of the major challenges for the methanol-to-hydrocarbon (MTH) reaction over acidic zeolites. Here we report the critical role of intermolecular π-interactions in catalyst deactivation in the MTH reaction on zeolites H-SSZ-13 and H-ZSM-5. π-interaction-induced spatial proximities between cyclopentenyl cations and aromatics in the confined channels and/or cages of zeolites are revealed by two-dimensional solid-state NMR spectroscopy. The formation of naphtalene as a precursor to coke species is favored due to the reaction of aromatics with the nearby cyclopentenyl cations and correlates with both acid density and zeolite topology.     

Deep-Eutectic-Solvent-Based Self-Healing Polymer Electrolyte for Safe and Long-Life Lithium-Metal Batteries

The deployment of high-energy-density lithium-metal batteries has been greatly impeded by Li dendrite growth and safety concerns originating from flammable liquid electrolytes. Herein, we report a stable quasi-solid-state Li metal battery with a deep eutectic solvent (DES)-based self-healing polymer (DSP) electrolyte. This electrolyte was fabricated in a facile manner by in situ copolymerization of 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate (UPyMA) and pentaerythritol tetraacrylate (PETEA) monomers in a DES-based electrolyte containing fluoroethylene carbonate (FEC) as an additive. The well-designed DSP electrolyte simultaneously possesses non-flammability, high ionic conductivity and electrochemical stability, and dendrite-free Li plating. When applied in Li metal batteries with a LiMn₂O₄ cathode, the DSP electrolyte effectively suppressed manganese dissolution from the cathode and enabled high-capacity and a long lifespan at room and elevated temperatures.