Winter breeding of black swan Cygnus atratus in a solar greenhouse with a water pond.

Winter propagation of black swans Cygnus atratus is introduced at Kwangpho on the east coast of the Democratic People's Republic of Korea located in the temperate zone of northeast Asia. The natural lake Kwangpho was selected as a rearing site to provide the environment which matched most closely to black swan's natural habitats. Comparison of the climate data of Kwangpho with Australia and New Zealand led to the conclusion that it is necessary to increase winter temperature 10 °C for artificial rearing. In order to overcome the low temperature with renewable energy, a passive solar greenhouse with a water pond was introduced, where black swans were reared simultaneously while observing the microclimate such as air temperature, humidity and water temperature in winter. When the pond depth was 0.4 m and 0.8 m, there was no significant difference in indoor temperature, the depth fixed at 0.4 m to reduce pumping power by more than 50%. During the study, 80 mature black swans wintered safely and 13 pairs of them laid 74 eggs, the artificial hatching rate was 65% and the natural hatching rate was 53%. It was confirmed that the passive solar greenhouse with a pond can raise the winter minimum temperature 8-10 °C higher than outside, and in this microclimate it is possible to propagate the black swan and it is believed that the greenhouse has abundant potential to enable the artificial breeding as well as wintering of black swans, in temperate zone occupying wide area of the earth.

A robust biocatalyst based on laccase immobilized superparamagnetic Fe3O4@SiO2-NH2 nanoparticles and its application for degradation of chlorophenols.

The presence of chlorophenols in water and wastewater is considered a serious environmental issue. To eliminate these micropollutants, biodegradation of chlorophenols using enzyme-nanoparticle conjugated biocatalyst, is proposed as an economical and eco-friendly method. Herein, amino-functionalized superparamagnetic Fe3O4@SiO2-NH2 nanoparticles with core-shell structure were constructed as a promising carrier for immobilization of laccase from Trametes versicolor. Compared with free laccase, Fe3O4@SiO2-NH2-Laccase displayed remarkable outcomes in all major areas such as temperature and storage stabilities, and tolerance to organic solvents and metal ions. The biocatalytic performance and reusability of Fe3O4@SiO2-NH2-Laccase were evaluated for the degradation of 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) in repeated cycles. Even after 10 successive reuses, the degradation rate of 2,4-DCP and 2,4,6-TCP were found to be 54.9% and 68.7%, respectively. The influences of solution pH, initial chlorophenol concentration, and temperature on the degradation rate of these two chlorophenols were evaluated. The degradation intermediate products including dimers, trimers, and tetramers of 2,4-DCP and 2,4,6-TCP were identified. Release of chloride ions was observed during the enzymatic degradation of these two chlorophenols. Based on the determination of intermediate products and released chloride ions, the degradation pathway that was involved in dehydrogenation, reactive radical intermediates formation, dechlorination, self-coupling and oligomers/polymers formation was proposed. The toxicity of these two chlorophenols and their intermediates was substantially reduced during the enzymatic degradation. The results of this study might present an alternative clean biotechnology for the remediation of 2,4-DCP and 2,4,6-TCP contaminated water matrices.

Superior elimination of Cr(VI) using polydopamine functionalized attapulgite supported nZVI composite: Behavior and mechanism.

In this study, a polydopamine (PDA) modified attapulgite (ATP) supported nano sized zero-valent iron (nZVI) composite (PDA/ATP-nZVI) was rapidly synthesized under acidic conditions, and employed to alleviate Cr(VI) toxicity from an aqueous solution. Kinetic studies revealed that Cr(VI) adsorption process followed the pseudo-second order model, suggesting chemisorption was the dominant adsorption mechanism. Liu isotherm adsorption model was able to better describe the Cr(VI) adsorption isotherm with the maximum adsorption capacity of 134.05 mg/g. The thermodynamic study demonstrated that the adsorption process occurred spontaneously, accompanied by the increase in entropy and endothermic reaction. Low concentrations of coexisting ions had negligible effects on the removal of Cr(VI), while high concentrations of interfering ions were able to facilitate the removal of Cr(VI). Reactive species test revealed that Fe2+ played a key role in Cr(VI) reduction by PDA/ATP-nZVI. PDA enhanced the elimination of Cr(VI) via donation of electrons to Cr(VI) and acceleration of Fe3+ transformation to Fe2+. Furthermore, PDA was able to effectively inhibit the leaching of iron species and generation of ferric hydroxide sludge. Mechanistic study revealed that 72% of Cr(VI) elimination was attributed to reduction/precipitation, while 28% of Cr(VI) elimination was due to the surface adsorption.

A comparative study on influences of static electric field and power frequency electric field on cognition in mice.

Recently, electromagnetic fields around ultra-high voltage transmission lines have received considerable attentions for their potential biological effects. This study aimed to investigate the effects of static electric field (SEF) and power frequency electric field (PFEF) on cognition. Mice were exposed to SEF and PFEF with the same strength (35 kV/m) for 49 days, respectively. Behaviors in Morris water maze test and amino acid neurotransmitter levels in hippocampus were examined during exposure. Results indicated that the exposure of 35 kV/m SEF would not cause significant influences on learning and memory ability in mice, while the exposure of 35 kV/m PFEF would cause significant positive effects on learning and memory ability in mice on day 33. This difference in effects from SEF and PFEF on cognition was possibly induced by the difference in the degree of molecular polarization and ion migration in organisms under exposure of two kinds of electric fields with different frequency.

The impact of PHB accumulation on L-glutamate production by recombinant Corynebacterium glutamicum.

Corynebacterium glutamicum, a gram-positive soil bacterium, has been used extensively for the industrial production of l-glutamate and other amino acids. In this study, an Escherichia coli-C. glutamicum shuttle expression plasmid harboring polyhydroxybutyrate (PHB) synthesis genes, phbCAB from Ralstonia eutropha, was constructed under the Ptrc promoter. C. glutamicum harboring this plasmid accumulated 3-13% PHB with a weight average molecular mass of 125,400 and a polydispersity of 11.3 when grown on glucose. PHB synthesis related enzyme activities including beta-ketothiolase (PhbA), acetoacetyl-CoA reductase (PhbB) and PHB synthase (PhbC) were found to be constitutively produced independent of IPTG. l-Glutamate production increased 39-68% in two C. glutamicum strains harboring PHB synthesis genes compared with their parent strains in shake flask experiments. In fermentor studies, the recombinant produced approximately 23% more l-glutamate compared with that of the wild type, and yielded less intermediate metabolites or by-products including alpha-ketoglutarate, l-glutamine and lactate. These results suggested that the expression of phbCAB genes in C. glutamicum could help regulate glutamate production metabolism. This demonstrated that the expression of PHB synthesis genes has a positive effect on l-glutamate production in C. glutamicum.