A pulsed switching peroxi-coagulation process to control hydroxyl radical production and to enhance 2,4-Dichlorophenoxyacetic acid degradation

The aim of this study was to develop a new pulsed switching peroxi-coagulation system to control hydroxyl radical(∙OH)production and to enhance 2,4-Dichlorophenoxyacetic acid(2,4-D)degradation.The system was constructed with a sacrifice iron anode,a Pt anode,and a gas diffusion cathode.Production of H_(2)O_(2) and Fe^(2+)was controlled separately by time delayers with different pulsed switching frequencies.Under current densities of 5.0 mA/cm^(2)(H_(2)O_(2))and 0.5 mA/cm^(2)(Fe^(2+)),the∙OH production was optimized with the pulsed switching frequency of 1.0 s(H_(2)O_(2)):0.3 s(Fe^(2+))and the ratio of H_(2)O_(2) to Fe^(2+)molar concentrations of 6.6.Under the optimal condition,2,4-D with an initial concentration of 500 mg/L was completely removed in the system within 240 min.The energy consumption for the 2,4-D removal in the system was much lower than that in the electro-Fenton process(686 vs.13610 kWh/kg TOC).The iron consumption in the system was~20 times as low as that in the peroxi-coagulation process(19620 vs.3940400 mg/L)within 240 min.The system should be a promising peroxi-coagulation method for organic pollutants removal in wastewater.

Quenching effect of deferoxamine on free radical-mediated photon production in luminol and ortho-phenanthroline-dependent chemiluminescence

Removing excessive free radicals （FRs） by a synthetic chemical might give a clue for treatment of many iron-mediated diseases. Deferoxamine （DFO） can be one of the chemicals of choice for the clue. To investigate photoredox properties of DFO, its quenching effect on superoxide radical （O2°）, hydrogen peroxide （H202） and hydroxyl radical （OH~） was examined using luminol and ortho-phenanthroline （o- phen） chemiluminescence （CL） systems and UV-vis spectrophotometry. Stern-Volmer equation was also used for the CL kinetics. The observed quenching effect of DFO on CL]photon production in luminol and o-phen CL systems strongly confirmed the static arm of quenching properties of DFO on OH° and H2O2, but much less pronounced on O2^-°; the quenching property was maximal when iron was involved in the reaction systems. The Stern-Volmer plots in the designed photochemical reaction systems also confirmed a potent quenching effect of DFO on FR-mediated CL. Our study highlights strong photoreducing and antioxidant properties of DFO with huge quenching capacity on excessive FRs, and thus implies its promising prospects for therapeutic applications.

Efficient and collective total synthesis of natural products via radical cascade reactions

Subject Code:B02With the support of the National Natural Science Foundation of China,the research team led by Prof.Qin Yong(秦勇)at Sichuan University accomplished a collective synthesis of 33 monoterpenoid indole alkaloids that belong to four families,by developing new photoredox-initiated radical cascade reactions.

保罗·赫斯特对马克思主义探索的历程论析

保罗·赫斯特曾对马克思主义进行过深入而细致的研究,家庭氛围的熏染、激进左翼思想的影响、将马克思的理论暗含于社会学研究的早期尝试,使他在马克思主义的研究中形成了独特的思想品格和精神气质。他的马克思主义探索历程经历了走向马克思主义、马克思主义思想的进一步探索到后马克思主义转向等十分复杂的阶段性思想转变过程。保罗·赫斯特的这种马克思主义思想演进路向具有三个方面的特点,分别是显现着英国新左派不同代际的理论特质、具有鲜明的史学理论底色以及与英国社会主义思潮的本土化步调有着某种程度的相像之处。