Dihydrodiol dehydrogenase (DD; EC 1.3.1.20) catalyzes the oxidation of polycyclic aromatic hydrocarbon (PAH) trans-dihydrodiols (proximate carcinogens) to catechols which rapidly autoxidize to yield o-quinones (Smithgall, T. E., Harvey, R. G., and Penning, T. M. (1988) J. Biol. Chem 263, 1814-1820). Although this pathway suppresses the formation of the PAH anti- and syn-diol epoxides (ultimate carcinogens), the process of autoxidation is anticipated to yield reactive oxygen species (ROS). We now show that the NADP+ dependent oxidation of (+/-)-trans-1,2-dihydroxy-1,2-dihydronaphthalene (Npdiol) and (+/-)-trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (Bpdiol) catalyzed by homogeneous DD is accompanied by the consumption of molecular oxygen and the production of H2O2. With both trans-dihydrodiol substrates, oxygen consumption was stoichiometric with H2O2 production consistent with the reaction: QH2 + O2 = H2O2 + Q, where QH2 is the catechol and Q is the o-quinone. Using Npdiol or Bpdiol as substrates, a burst of superoxide anion production is catalyzed by DD which can be detected as the rate of cyt c reduction that is inhibited by superoxide dismutase. Using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as spin-trapping agent, secondary spin adducts corresponding to DMPO-CH3 were formed during the enzymatic oxidation of Npdiol and Bpdiol. The formation of the CH3. radical arises from the OH. attack of DMSO, which was used as cosolvent. These spin adducts were attenuated by superoxide dismutase and catalase, implying that O2-. and H2O2 are obligatory for the formation of DMPO-CH3. It is proposed that O2-. is the radical that propagates autoxidation and that the resultant H2O2 undergoes Fenton chemistry to produce the OH. radical. Identical spin adducts were observed using a superoxide anion generating system (hypoxanthine/xanthine oxidase) and DMPO as spin-trapping agent in the presence of DMSO. The ability of DD to generate ROS during the oxidation of PAH trans-dihydrodiols (proximate carcinogens) may have important implications for tumor initiation and promotion.

Owing to its high theoretical capacity of~4200 mAh g −1 and low electrode potential (<0.35 V vs. Li + /Li), utilising silicon as anode material can boost the energy density of rechargeable lithium batteries. Nevertheless, the volume change (~300%) in silicon during lithiation/ delithiation makes stable cycling challenging. Since some of the capacity fading mechanisms do not function in solid electrolytes, silicon anodes exhibit better cycling performance in solid electrolytes than liquids. Nonetheless, capacity can fade rapidly because of the difficulties in maintaining mechanical integrity in thick/bulky electrodes, especially when high active material loading is employed to deliver practically useful areal capacity. By contrast, silicon nanostructures can relieve deformation-induced stress and enhance cycling performance. Here we report enhanced cycling performances achieved using nanostructured silicon films and inorganic solid electrolyte and show that amorphous porous silicon films maintain high capacity upon cycling (2962 mAh g −1 and 2.19 mAh cm −2 after 100 cycles).

Solid-state lithium batteries are regarded as promising energy storage devices that meet the requirements for realizing a low-carbon society. Although solid-state batteries have been suffering from low power density, the power density has become comparable to or greater than that of liquid systems in a recently developed battery, which has been achieved not only by the high ionic conductivity of the used sulfide solid electrolyte. This Perspective presents anomalous transport properties appearing at the interfaces in solid-state batteries to highlight the importance of controlling the interface phenomena in achieving the high performance. The battery employs not only the highly conductive sulfide but also some oxides in spite of their low conductivity. LiNbO3 interposed to the cathode interface effectively reduces the cathode impedance by suppressing lithium depletion at the interface. Li4Ti5O12 used as the anode becomes a good conductor in its two-phase region because of enhanced transport properties at the phase boundaries.

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This paper reports the electrode performance of a Si anode composed of nanoparticles prepared by spray deposition in a solid-state cell. Upon lithiation, the Si nanoparticles undergo volume expansion, structural compaction, and appreciable coalescence in the confined space between the solid electrolyte layer and current collector in the solid-state cell to form a continuous film similar to that fabricated by the evaporation process. Hence, the particulate anode exhibited excellent performance, previously observed only in thin-film systems. The anode prepared by the scalable process delivers 2655 mAh g −1 even at a high discharge current density of 5.48 mA cm −2 (24C).