Simple preparation of ordered mesoporous carbons assisted by an organosilicate as a linking material

Ordered mesoporous carbon materials (OMCs) were prepared from a silica–carbon composite assisted by 3-mercaptopropyltrimethoxysilane (MPTMS) in an aqueous phase. The obtained OMCs have a high surface area, large pore volume and uniform pore structure. MPTMS plays an important role in linking the polymer part with silica part to form a mesoporous structure. Importantly, the amount of MPTMS used is an important determinant in the development of a uniform mesoporosity. The method described herein has some important advantages over existing methods, such as simplified synthesis steps for the preparation of OMCs, the fact that the aqueous phase can be used and that the resulting materials have a high surface area of more than 1700 m²/g.     

Increasing the toughness of nylon 12 by the incorporation of functionalized graphene

The effect of functionalized graphene (FG) on the mechanical properties, especially toughness, of nylon12 was investigated. The results revealed that the incorporation of a very small amount (about 0.6 wt%) of the FG caused a significant improvement in ultimate tensile strength, elongation, impact strength and toughness. With 0.6 wt% FG ultimate tensile strength and elongation at break of the nylon 12 are improved by ∼35% and ∼200%, respectively. The K_Ic of the nylon 12 is ∼1.28 MPa m^0.5 and the incorporation of 0.6 wt% FG causes a significant increase of 72% (∼2.2 MPa m^0.5). 0.6 wt% FG also causes a significant improvement of 175% in impact failure energy of the nylon 12. The incorporation of FG resulted in an increase in amount of γ-phase of nylon12 which could be the direct reason for the increase of toughness.     

Nanorod-assembled spinel Li1.05Mn1.95O4 rods with a central tunnel along the rod-axis for high rate capability of rechargeable lithium-ion batteries

Nanorod-assembled spinel Li_1.05Mn_1.95O₄ rods with a central tunnel along the rod-axis were synthesized using highly crystalline β-MnO₂ rods as self-templates. The synthesized spinel Li_1.05Mn_1.95O₄ is an assembly of several single crystal-like nanorods with an average diameter and length of 100 and 400 nm, respectively, which was determined by microstructural Rietveld refinement using the synchrotron powder XRD data. Galvanostatic battery testing showed that central-tunneled and nanorod-assembled Li_1.05Mn_1.95O₄ rods have a high charge storage capacity at high current densities in comparison with those of the spinel rods without a tunnel structure and commercial powders. Moreover, a capacity retention value of ∼81% was observed at the end of 100 cycles at a current of 250 mAh g⁻¹.     

Electrostatic heterocoagulation of carbon nanotubes and LiCoO2 particles for a high-performance Li-ion cell

Nanotubes were coated on the surface of active LiCoO₂ particles using electrostatic heterocoagulation to enhance the electrochemical properties of a Li-ion battery. Only 0.5 wt% of multiwalled carbon nanotubes (MWCNTs) was added as a conducting agent into the LiCoO₂ cathode, which had a density of 4.0 g cm⁻³. We found that our electrode that was prepared using heterocoagulation with 0.5 wt% of thin MWCNTs maintained a volumetric capacitance of 403 mAh cm⁻¹ after 40 cycles from the initial 624 mAh cm⁻¹, compared with previous result of 310 mAh cm⁻¹ obtained from simple mixing with 3 wt% MWCNTs. The high volumetric capacity with smaller swelling using less amount of MWCNTs was attributed to the self-assembled nanotube network formed between active particles during coagulation, which was maintained with volume expansion during cycle testing.     

Effect of Contact Mode on the Electrical Transport and Field‐Emission Performance of Individual Boron Nanowires

Vapor–liquid–solid processing of boron nanowires (BNWs) can be carried out either using a bottom‐up or top‐down growth mode, which results in different contact modes between the nanowire and the substrate. The contact mode may strongly affect the electrical transport and field‐emission performance of the individual boron nanowires grown on a Si substrate. The electrical transport and field‐emission characteristics of individual boron nanowires of different contact modes are investigated in situ using a scanning electron microscope. The contact barriers are very distinct for the different contact modes. Moreover, the transition from a “contact‐limited” to a “bulk‐limited” field‐emission (FE) process is demonstrated in nanoemitters for the first time, and the proposed improved metal–insulator–vacuum (MIV) model may better illustrate the nonlinear behavior of the Fowler‐Nordheim (FN) plots in these nanoscale systems. Individual BNWs with different contact modes have a discrepancy in their emission stability and vacuum breakdown characteristics though they have similar aspect ratios, which suggests that their electrical transport and field‐emission performance are closely related to their contact mode. Boron nanowires grown in the base‐up mode have better field‐emission performances and are more beneficial than those grown in the top‐down mode for various device applications.     

我国科普资源共享发展战略研究

我国科普资源共享在我国科普工作中具有基础性、牵动性的地位。本文在深入调研基础上,分析了公共科普资源共享的发展现状、工作难点和存在问题,探讨提出了科普资源共享工作下一步发展的指导思想、战略目标及工作原则,并有针对性地提出了下一步工作的若干建议。     

科研机构向公众开放活动中的问题研究——以中科院为例

科研机构向公众开放是其重要的社会责任和义务,有利于提升我国的科普能力。近年来,中科院利用自身的资源优势开展了“公众科学日”等开放的活动,本文在深入调研的基础上,从政策、组织运行、经费、评价激励等方面入手,对中科院向公众开放过程中存在的问题进行了分析,并尝试提出解决问题的建议。     

Novel chains constructed from heterotrinuclear units and 1,2-bis(4-pyridyl)ethane formulated as [M2M′(O2CPh)6](bpa) (M = Co,Zn, M′ = Co,Cd): Their catalytic activity

Three novel heterometallic complexes containing two bridging ligands bpa and benzoate, formulated as [M₂M′(O₂CC₆H₅]_n(bpa)_n (bpa = 1,2-bis(4-pyridyl)ethane, M₂M′ = Zn₂Co (1), Zn₂Cd (2), and Co₂Cd (3)), have been synthesized. All three compounds show one-dimensional structures containing linear heteronuclear coordination units linked by bridging bpa ligands. Reactivity study of the compounds 1–3 for the transesterification of a variety of esters has shown that they are very efficient and 2 is the best among them.     

Two isomers containing a [Cu(Me2bpzb)] unit: Molecule (0-D) and 1-D

Two isomers (molecule 1 and 1-D 2) containing [Cu(Me₂bpzb)] units have been obtained under the different reaction conditions, and their structures have been determined by X-ray crystallography. From the temperature-dependent magnetic data for 2, there was no interaction between Cu²⁺ ions through the ligand. The photoluminescence of the free H₂Me₂bpzb molecule displayed an intense emission band centered at about 482 nm, while complexes 1 and 2 exhibited no obvious emission bands.     

Synthesis and spectroscopic properties of novel phthalimide‐derived monoazo disperse dyes containing ester groups

The synthesis and spectroscopic properties of monoazo dye series, whose members consist of N‐alkylphthalimide diazo components combined with a coupling component containing two ester groups, are reported. Such colourants are potentially alkali‐clearable as a consequence not only of the presence of diester functionality on the coupler, but also through use of the base‐sensitive phthalimide system. Shortening the N‐alkyl group by removing one or two methylene units from a butyl chain made little difference to absorption properties, as would be expected given the relatively minor differences in inductive character produced. Shifts in the absorption maximum of the dyes associated with dibromination of the phthalimidylazo motif and its subsequent cyanodehalogenation were in agreement with theory and literature data for related series. Diester substitution on the coupling component brought about hypsochromism and hypochromism.