Radical grafting of polyethylene onto MWCNTs: A model compound approach

Covalent functionalization of pentadecane-decorated multiwalled carbon nanotubes (MWCNTs) has been studied as a model compound approach for the grafting of poly(ethylene-co-1-octene) onto MWCNTs by reactive extrusion. It was accomplished through radical addition onto unsaturated bonds located on the MWCNTs' surface using dicumyl peroxide as hydrogen abstractor. It was found that this surface treatment results into the break-up of the native nanotube bundles and increases solubility in various solvents. Raman spectroscopy was utilized to follow the introduction of pentadecane on the MWCNTs' surface; while thermogravimetric analysis and elemental analysis indicated the extent of this grafting. Pentadecane functionalized MWCNTs were imaged by transmission electronic microscopy showing single long functionalized MWCNTs distinct from the starting pristine bundles.     

Ozonation of Trace Nitrobenzene in Water in the Presence of a TiO2/Silica-Gel Catalyst

Heterogeneous catalytic ozonation was investigated for the degradation of nitrobenzene in the presence of TiO₂ supported on Silica-gel as a solid catalyst. The conditions in preparing the catalyst are experimentally optimized. The catalytic activity of the supported TiO₂ is strongly influenced by the calcination temperature. The TiO₂/Silica-gel calcined at 500 °C showed the highest activity for the degradation of nitrobenzene. An approximate increase of 21% in removal efficiency was achieved for catalytic ozonation compared with the case of ozonation alone. Nitrobenzene degradation was significantly influenced by the presence of carbonate and t-butanol, which confirmed that TiO₂/Silica-gel catalyzed ozonation followed a radical-type mechanism. Kinetic study demonstrated that catalytic ozonation is pseudo–first-order with no respect to the initial nitrobenzene concentration. The effect of catalyst dosage and pH on the oxidation efficiency of nitrobenzene was also investigated. Catalyst dosage exerted a positive influence on nitrobenzene removal, and nitrobenzene degraded more completely under neutral or basic conditions. Finally, the catalyst stability was tested through repeated experiments.     

激进的回溯——20世纪60-70年代乌托邦理念对当代地下空间发展的启示

对于地下空间的回溯性思考,通过聚焦历史中持久的批判性,激发知识的重构力量,将有助于基于过去面向未来找寻迭代提升的机会。本文试图通过聚焦20世纪60—70年代的城市建筑理念,连接对地下空间发展的思考,以一种映射参与性、空间结构化、同质异质性的切入尝试思考地下空间,试图进一步看待地下空间可以被“一体化”“异质化”以及被进一步发掘的潜在意义。     

Unraveling the discriminative mechanisms for peroxy activation via atomically dispersed Fe-N5 sites for tunable water decontamination

The discriminative activities and mechanisms for activation of O-O bond in peroxy compounds via single-atom catalysts (SACs) especially with a higher coordination number (M-N₅) are rarely explored. Herein, the atomic catalyst (Fe-SAC) with Fe-N₅ as the active center was constructed, which could simultaneously and effectively activate peroxymonosulfate (PMS), peroxydisulfate (PDS), and hydrogen peroxide (H₂O₂). Density functional theory (DFT) calculations combined with experiments results demonstrated that the degradation efficiencies of acyclovir were corresponding to the changes of O-O bond length in various peroxy compounds. Meanwhile, the experiments exposed that the three oxidants all produced ^•OH, but the PMS also contained ¹O₂ and Fe(IV)=O, and PDS contained O₂^•- additively. The scale-up experiment showed Fe-SAC could operate steadily for nearly 7 d. Overall, this work unveils the discriminative mechanisms for activation of O-O band in different Fenton-like systems. Moreover, the Fe-SAC with high coordination numbers has excellent catalytic properties and practical performance.     

Benzylic Fragmentation (BFR), an Aromatic Analogue of E1cB Including a Homolytic Variant,as either Nucleofugal or Homolytic Path to Aryl Stabilized Carbanions or Ketyls,respectively

BFR is the decisive step of novel reductions at benzyl‐type carbons that may complement available methods. BFR is mechanistically important for understanding and control of curious findings in radical anion chemistry. Driving force of BFR is rearomatization of a dihydroarene species usually derived from anthracene. This intermediate 1 arises (solvent THF) either from coupling of anthracenidyl A ^°− with a benzyl radical or from nucleophilic reaction of anthracene hydride AH ⁻ with a benzylic electrophile followed by CH ₂ deprotonation (excess AH ⁻ ) of the generated 9‐benzyl‐dihydroanthracene. 1 spontaneously undergoes BFR either heterolytically or homolytically depending on the stabilities of carbanion 2 (or even dianion 2 , e.g. from chalcone) and ketyl 3 . BFR is more rapid with counterion Na⁺ than with Li⁺ . The overall reaction is a selective one electron (innersphere eletron transfer) or two electron reduction of a benzylic electrophile, sometimes under expected subsequent rearrangement. This account reports on mechanism and scope of these reductions; a few related cases are described.     

Mixing Up the Mediterranean Model: Architecture Amid Urban Flux

The Radical movement born in 1960s Italy sparked a rethinking of the urban landscape. Its key proponents, such as Andrea Branzi, understand the city as a constantly fluctuating organism, rather than an ever-expanding Modernist assembly of parts with fixed functions. Luca Molinari – Professor of History and Theory of Contemporary Architecture at the Università degli Studi della Campania ‘Luigi Vanvitelli’, Naples – reflects on how this organic model recalls that of traditional Mediterranean towns. He traces the spread of its influence around the world in recent decades, and asks whether it could be a solution to the decline of suburbia in economically advanced nations.     

海带中褐藻糖胶的提取及其对自由基清除能力的研究

以海带为原料提取褐藻糖胶，并初步研究了一些因素对褐藻糖胶的自由基清除能力的影响。研究表明，褐藻糖胶的最佳提取温度为100℃，提取时间为6h，加水量为90mL/g，得率为11．05％，温度对自由基清除能力影响不大，浓度与自由基清除能力正相关。