STUDY ON TOLERANCE TO OXYGEN DEFICIENCY,GENETIC STABILITY AND ECOLOGICAL FITNESS OF PSOCID, Liposcelis bostrychophila BADONNEL (Psoceoptera:Iposcelididae)

At the present paper,adult populations of the psocid, Liposcelis bostrychophila ,were exposed respectively for 30 generations to two atmospheres containing 0 5% and 1% O 2 (N 2 in mixture as balance),in order to select strains resistant to low O 2 content (LOC) atmosphere.Selection pressure was maintained at around 70% mortality.At the 30th generation,comparison of sensitivity between the selected strains (LOC1 and LOC2) and the original susceptible strain (CA S) indicated a tolerance factor (TF) at the 50% mortality level (LT 50 ) of 4 7 and 3 9 fold,respectively.Throughout the selection process,log time against probit mortality lines remained roughly parallel and the slopes remained lower than that of CA S strain until the last generation.The implication is that at high level of selection,multiple genetic factors continued act together even at the 30th generation to select for adaptation to survival at depleted O 2 concentration.Up to 30th generation,two selected strains still possessed the genetic potential to develop resistance to LOC.Removal of selection pressure for 5 generations from 2 sub populations of two selected strains from 25th generation caused significant reduction in resistance.In the absence of CA exposure,the two selected strains all possessed the reproductive disadvantages or fitness defect.LOC1 and LOC2 were calculated by R 0 to have a fitness value of 0 56 and 0 75 relative to unselected strain,respectively.

Enzyme-assisted Photoinitiated Polymerization-induced Self-assembly in Continuous Flow Reactors with Oxygen Tolerance

Polymerization-induced self-assembly(PISA)is an emerging method for the preparation of block copolymer nano-objects at high concentrations.However,most PISA formulations have oxygen inhibition problems and inert atmospheres(e.g.argon,nitrogen)are usually required.Moreover,the large-scale preparation of block copolymer nano-objects at room temperature is challenging.Herein,we report an enzyme-assisted photoinitiated polymerization-induced self-assembly(photo-PISA)in continuous flow reactors with oxygen toleranee.The addition of glucose oxidase(GOx)and glucose into the reaction mixture can consume oxygen efficiently and constantly,allow the flow photo-PISA to be performed under open-air conditions.Polymerization kinetics indicated that only a small amount of GOx(0.5 μmol/L)was needed to achieve the oxygen tolerance.Block copolymer nano-objects with different morphologies can be prepared by varying reaction conditions including the degree of polymerization(DP)of core-forming block,monomer concentration,reaction temperature,and solvent composition.We expect this study will provide a facile platform for the large-scale production of block copolymer nano-objects with different morphologies at room temperature.

Oxygen tolerance capacity of upflow anaerobic solid-state(UASS) with anaerobic filter(AF) system

In order to investigate the oxygen tolerance capacity of upflow anaerobic solid-state（UASS）with anaerobic filter（AF） system, the effect of microaeration on thermophilic anaerobic digestion of maize straw was investigated under batch conditions and in the UASS with AF system. Aeration intensities of 0–431 m L O2/gvswere conducted as pretreatment under batch conditions. Aeration pretreatment obviously enhanced anaerobic digestion and an aeration intensity of 431 m L O2/gvsincreased the methane yield by 82.2%. Aeration intensities of 0–355 m L O2/gvswere conducted in the process liquor circulation of the UASS with AF system. Dissolved oxygen（DO） of UASS and AF reactors kept around 1.39 ±0.27 and 0.99 ± 0.38 mg/L, respectively. p H was relatively stable around 7.11 ± 0.04. Volatile fatty acids and soluble chemical oxygen demand concentration in UASS reactor were higher than those in AF reactor. Methane yield of the whole system was almost stable at 85 ± 7 m L/gvs as aeration intensity increased step by step. The UASS with AF system showed good oxygen tolerance capacity.

Proton reduction in the presence of oxygen by iron porphyrin enabled with 2nd sphere redox active ferrocenes

Hydrogen evolution in the presence of atmospheric level of oxygen is a significant barrier in the quest for an alternative,sustainable and green source of energy to counter the depleting fossil fuel sources and increasing global warming due to fossil fuel burning.Oxygen reduction is thermodynamically more favourable than proton reduction and it often produces reactive oxygenated species upon partial reduction which deactivates the catalyst.Thus,catalyst development is required for efficient proton reduction in the presence of oxygen.Here,we demonstrate an iron porphyrin having triazole containing 2nd sphere hydrogen bonding residues appended with redox active ferrocene moieties(α4-Tetra-2-(3-ferrocenyl-1,2,3-triazolyl)phenylporphyrin(FeFc4))as a bifunctional catalyst for fast and selective oxygen reduction to water and thus,preventing the proton reduction by the same catalyst from oxidative stress.Fe(0)is the active species for proton reduction in these iron porphyrin class of complexes and it is observed that the kinetics of proton reduction at Fe(0)state occurs at much faster rate than O2 reduction and thus,paving the way for selective proton reduction in the presence of oxygen.

Hydrogenase as the basis for green hydrogen production and utilization

Hydrogenase is a paradigm of highly efficient biocatalyst for H_(2) production and utilization evolved in nature. A dilemma is that despite the high activity and efficiency expected for hydrogenases as promising catalysts for the hydrogen economy, the poor oxygen tolerance and low yield of hydrogenases largely hinder their practical application. In these years, the enigmas surrounding hydrogenases regarding their structures, oxygen tolerance, mechanisms for catalysis, redox intermediates, and proton-coupled electron transfer schemes have been gradually elucidated;the schemes, which can well couple hydrogenases with other highly efficient(in)organic and biological catalysts to build novel reactors and drive valuable reactions, make it possible for hydrogenases to find their niches. To see how scientists put efforts to tackle this issue and design novel reactors in the fields where hydrogenases play crucial roles, in this review,recent advances were summarized, including different strategies for protecting enzyme molecules from oxygen, enzyme-based assembling systems for H_(2) evolution in the photoelectronic catalysis, enzymatic biofuel cells for H_(2) utilization and storage and the efficient electricity-hydrogen-carbohydrate cycle for high-purity hydrogen and biofuel automobiles. Limitations and future perspectives of hydrogenasebased applications in H_(2) production and utilization with great impact are discussed. In addition, this review also provides a new perspective on the use of biohydrogen in healthcare beyond energy.

Living Bacteria-Mediated Aerobic Photoinduced Radical Polymerization for in Situ Bacterial Encapsulation and Differentiation

Conventional polymerizations mediated by living cells typically require synthetic transition-metal complexes or photoredox catalysts.Herein,we report an alternative photoinduced polymerization strategy for preparing functional polymer hydrogels through bacteria-initiated radical polymerization of acrylamides in ordinary culture media.Upon light irradiation under ambient conditions,polyacrylamides were obtained with molecular weights of over 150 kDa using various bacteria.