Highly monodisperse magnetite/carbon composite microspheres with a mesoporous structure as high-performance lithium-ion battery anodesLim, Hyung-Seok; Kim, Daun; Hwang, Jun-Ki; Kim, Yu-Jeong; Sun, Yang-Kook; Suh, Kyung-Do
doi: 10.1039/c5ra05732apmid: N/A
In this study, we propose a fabrication method for highly monodisperse magnetite/carbon (Fe3O4/C) composite microspheres with a mesoporous structure. Highly monodisperse porous polystyrene (PS) microspheres are synthesized by traditional seeded polymerization. Textural properties of porous PS microspheres can be controlled by using different amounts of diluent. In order to carbonize and introduce ferrous (Fe2+) and ferric (Fe3+) ions into the pores of PS microspheres, the sulfonation reaction is carried out using sulfuric acid. Fe3O4 nanocrystals are formed in the pores as well as on the surface of the sulfonated porous PS microspheres by a simple wet chemical method. The obtained mesoporous structure of the Fe3O4/C composite microspheres is still retained after a heat treatment in a nitrogen atmosphere. The homogeneous distribution of Fe3O4 nanocrystals in the porous carbon matrix was analyzed through elemental mapping by preparing cross-sections using focused ion beam scanning electron microscopy milling. When the composite electrodes are tested as an anode material in a Li-ion half-cell, the mesoporous Fe3O4/C composite microspheres exhibit not only a high reversible capacity of 562 mA h g−1 after 100 cycles at 1 C but also good capacity retention at various current rates (0.1–10 C) with a high coulombic efficiency of above 99%.
Extension of three-dimensional activity cliff information through systematic mapping of active analogsHu, Ye; Furtmann, Norbert; Bajorath, Jürgen
doi: 10.1039/c5ra01732gpmid: N/A
Activity cliffs are formed by pairs or groups of structurally similar or analogous compounds with large potency differences against a given target. Three-dimensional activity cliffs (3D-cliffs) are obtained by comparison of the binding modes of ligands in complex X-ray structures. Currently, 630 high-confidence 3D-cliffs are available for a total of 61 human targets, which provide a knowledge base for structure-based SAR exploration and compound design. In this work, a systematic search for structural analogs of 3D-cliff compounds was carried out applying a variant of the matched molecular pair (MMP) formalism to further extend the structure–activity relationship (SAR) information associated with 3D-cliffs. In many instances, series of active analogs were successfully mapped to 3D-cliffs. Compound relationships were explored in network representations and key compounds involved in the formation of multiple 3D-cliffs and structural relationships identified. In addition, the superposition of analogs onto 3D-cliffs helped to rationalize distinguishing interactions and potency variations. In total, 1980 analogs were identified for 268 cliff compounds active against 50 human targets, which further extended 414 3D-cliffs and provided a variety of SAR environments for further study. A database comprising the currently available 3D-cliffs and assigned analogs has been generated and is freely available.
Effect of sodium chloride on the electrochemistry activity of electrodeposited CdTe films with various morphologiesWang, Jun; Li, Qian; Mu, Yannan; Zhou, Xiaoming; Yang, Lihua; Lv, Pin; Su, Shi; Niu, Jiasheng; Fu, Wuyou; Yang, Haibin
doi: 10.1039/c5ra05885fpmid: N/A
In this paper, a cadmium telluride (CdTe) film is successfully synthesized on Ni foils via a simple electrochemical deposition method. Especially, with sodium chloride (NaCl) being added into the electrolyte directly, an interesting morphology evolution from spherical CdTe film to rod-shaped CdTe film, then to clustered CdTe film, and finally to double-layered film is observed with the increase of the NaCl concentration. The products are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV-vis spectroscopy, and photoelectrochemical measurements. It is found that the amount of NaCl played an important role in determining the morphology of CdTe film. The possible growth mechanism is discussed as well. Photoelectrochemical measurements reveal that the morphology of CdTe film can affect their photoelectrical properties greatly, and the uniform CdTe nanorod arrays prepared at 0.05 mol L−1 NaCl exhibit excellent photoelectrical properties, which is meaningful to the investigation of CdTe solar cells. According to the experiments, this simple but effective method can also be extended to the control of the growth of other nanostructures.
Quantifying the co-solvent effects on trypsin from the digestive system of carp Catla catla by biophysical techniques and molecular dynamics simulationsReddy, P. Madhusudhana; Taha, M.; Sharma, Y. V. R. Kameshwar; Venkatesu, Pannuru; Lee, Ming-Jer
doi: 10.1039/c5ra01302jpmid: N/A
Here, circular dichroism (CD) spectroscopy, fluorescence spectroscopy, UV-Vis spectroscopy, SDS-PAGE, substrate SDS-PAGE, and molecular dynamics (MD) simulations techniques have been employed to understand the structural behavioral changes of trypsin (MW: 19.72 kDa, source: digestive system of adult Indian major carp, Catla C. catla) in the presence of various chemical environments. The stability of the trypsin can be increased by stabilizers, including trimethylamine N-oxide (TMAO), proline, and betaine, without affecting its native structure. Trypsin has shown unusual high thermal stability in the presence of betaine. Further, these experimental results were confirmed by means of MD simulations. The present results explicitly elucidated that the behavior of a co-solvent may vary depending upon the type of the protein.
Polymer nanocomposite foam filled with carbon nanomaterials as an efficient electromagnetic interference shielding materialDhakate, Sanjay R.; Subhedar, Kiran M.; Singh, Bhanu Pratap
doi: 10.1039/c5ra03409dpmid: N/A
Increasing use of the latest electronic gadgets in modern society causes rapid growth in electromagnetic pollution, which leads to detrimental effects on the function of highly sensitive precision electronic equipment as well as on human life. Mitigating this effect requires efficient electromagnetic radiation shielding materials, which should be lightweight, corrosion resistant and cost-effective. In this review article, we have presented lightweight polymer composite foams filled with carbon nanofibers, carbon nanotubes and graphene as efficient electromagnetic radiation shielding materials. It is seen that the low loading of multiwalled carbon nanotubes with uniform dispersion in polymer, uniform cell size of pore and controlled dielectric constant results in the attenuation of electromagnetic radiation by absorption phenomena. Flexible graphene–polymer composite foam derived using the chemical vapor deposition technique demonstrates a specific shielding effectiveness of ∼333 dB cm3 g−1, which is the highest value among those reported in literature. The SE is mostly dominated by the absorption of electromagnetic radiation, which is due to the multiple reflection of radiation inside the cells of the composite foam. Moreover, different carbon nanomaterial, such as carbon nanofibers and few layer graphene-filled polymer composite foams, with varying content of conducting filler are reported in this review. Their use in different applications, their future prospective and the challenges ahead are discussed in this review.
Effects of agricultural waste-based conditioner on ultrasonic-aided activated sludge dewateringGuo, Shaodong; Qu, Fangshu; Ding, An; He, Junguo; Yu, Huarong; Bai, Langming; Li, Guibai; Liang, Heng
doi: 10.1039/c5ra05743dpmid: N/A
The effects of agricultural wastes on ultrasonic-aided activated sludge dewaterability were investigated in this study. Wheat straw powder (WSP), corn stalk powder (CSP) and rice hull powder (RHP) were used as physical conditioners. Several indicators, including capillary suction time (CST), specific resistance to filtration (SRF) and the dewatering process were adopted to characterize the sludge dewaterability. Soluble protein and filtrate polysaccharide were also characterized to estimate their function on sludge dewatering. The results showed that sludge dewaterability was greatly improved by adding WSP or CSP under an ultrasonic intensity of 28 kHz. The SRF was reduced from 1.0 × 109 S2 g−1 to 0.4 × 109 S2 g−1 (or less) with a dosage of more than 0.75 g/g dry solid (DS). The moisture content of the sludge cake decreased from 93% to 80% and from 94% to 79% by adding WSP and CSP with ultrasonication. However, no visible enhancements were observed in sludge dewaterability by adding RHP. Moreover, the addition of these agricultural wastes contributed to an increase in the high heating value of dewatered sludge, and ultrasonication further improved the sludge low heating value by reducing the moisture content. The synergistic mechanism of sludge conditioned by agricultural wastes and ultrasonication was attributed to agricultural wastes forming a permeable and rigid lattice structure and ultrasonication cracking the sludge structure.
A mixed-function-grafted magnetic mesoporous hollow silica microsphere immobilized lipase strategy for ultrafast transesterification in a solvent-free systemZheng, Mingming; Mao, Lijing; Huang, Fenghong; Xiang, Xia; Deng, Qianchun; Feng, Yuqi
doi: 10.1039/c5ra05611jpmid: N/A
Although enzymatic catalysis is an attractive approach for the green synthesis of chemicals, it often suffers from low reactivity and poor stability during the reaction. In this study, lipase from Candida rugosa (CRL) was immobilized and stabilized on magnetically-separable, mixed-function-grafted, large pore mesostructured magnetic hollow mesoporous silica microspheres (MHMSS) by means of multiple-mode adsorption based on both hydrophobic and strong cation-exchange interactions. Benefiting from the hollow large mesoporous structure, ultrafast enzyme immobilization could be realized in 5 min, with a high loading of CRL (95.2 mg g−1). Stabilized CRL@MHMSS was successfully used for the ultrafast transesterification of phytosterol with fatty acids and triglycerides in a solvent-free system, which reached high conversions (≧90.9%) within 15 min at 55 °C. Magnetic separation of MHMSS facilitated the repeated usage of CRL@MHMSS for more than 50 successive reactions without damaging its catalytic activity. Its high activity and stability make the MHMSS immobilized enzyme an attractive catalyst for green synthesis in a solvent-free system.
Solar light sensitive samarium-doped ceria photocatalysts: microwave synthesis, characterization and photodegradation of Acid Orange 7 at atmospheric conditions and in the absence of any oxidizing agentsMandal, Bappaditya; Mondal, Aparna
doi: 10.1039/c5ra03758apmid: N/A
Novel, high surface area, mesoporous and crystalline samarium-doped ceria (CeO2:Sm3+) nanopowders were successfully synthesized by combining the excellent properties of both microwave heating and surfactants and were used as remarkably efficient new photocatalysts for the degradation of a representative azo dye, Acid Orange 7 (AO7), in an aqueous medium under natural sunlight without the addition of any external reagents like peroxide, acid or base. The synthesized nanopowders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis and UV-vis diffuse reflectance spectroscopy. The effects of calcination temperature, pH of the medium, catalyst dosage and irradiation time on the decolorization of AO7 were investigated and are discussed in this paper. Sm3+ doping in CeO2 narrowed the band gap and significantly enhanced the photocatalytic degradation of the azo dye. The photocatalytic degradation of AO7 was also investigated by using certain radical scavengers and the results suggest that under solar light irradiation predominantly positive holes and superoxide radicals (O2˙−) act as the active species in the degradation process. Our results suggest that the materials developed here are a promising alternative solar light sensitive photocatalyst.