Dynamics of ammonia oxidizers and denitrifiers in response to compost addition in black soil, Northeast China

Organic fertilizer application could have an impact on the nitrogen cycle mediated by microorganisms in arable soils. However, the dynamics of soil ammonia oxidizers and denitrifiers in response to compost addition are less understood. In this study, we examined the effect of four compost application rates (0, 11.25, 22.5 and 45 t/ha) on soil ammonia oxidizers and denitrifiers at soybean seedling, flowering and mature stage in a field experiment in Northeast China. As revealed by quantitative PCR, compost addition significantly enhanced the abundance of ammonia oxidizing bacteria (AOB) at seedling stage, while the abundance of ammonia oxidizing archaea was unaffected across the growing season. The abundance of genes involved in denitrification (nirS, nirK and nosZ) were generally increased along with compost rate at seedling and flowering stages, but not in mature stage. The non-metric multidimensional scaling analysis revealed that moderate and high level of compost addition consistently induced shift in AOB and nirS containing denitrifers community composition across the growing season. Among AOB lineages, Nitrosospira cluster 3a gradually decreased along with the compost rate across the growing season, while Nitrosomonas exhibited an opposite trend. Network analysis indicated that the complexity of AOB and nirS containing denitrifiers network gradually increased along with the compost rate. Our findings highlighted the positive effect of compost addition on the abundance of ammonia oxidizers and denitrifiers and emphasized that compost addition play crucial roles in shaping their community compositions and co-occurrence networks in black soil of Northeast China

Three Representative Island Microgrids in the East China Sea: Key Technologies and Experiences

In recent years, providing green and reliable energy supply to islands has appeared in the strategic plans of many countries. This paper introduces three representative island microgrids that have been built and are operating in the East China Sea. Key technologies of the island microgrids are discussed, including the analysis of island resources and load, selection of energy storage, control strategies, and energy management systems. Through analyzing their operation data for one year, this paper demonstrates the impacts of the three microgrids from the perspectives of technology, economics, and sustainability. Summarizing the experiences and insights gained from their construction and operation, this paper provides references for the future development of island microgrid projects

CD spectroscopy as a fingerprint technique for the structural characterization and determination of absolute configurations of unsymmetric chiral Schiff base Ni(II) complexes

Unsymmetric Schiff base complexes have attracted more attention in recent years due to their diverse effects in catalytic reactions. Due to their high dissymmetry, unsymmetric metallosalen complexes are harder to prepare than symmetric ones. This means that X-ray crystallographic structural determination is sometimes unavailable, so their absolute configurations are determined by circular dichroism (CD) spectroscopy instead. Herein, some quadridentate unsymmetric metallosalen nickel(l]) complexes were synthesized and their structures were characterized by CD spectra. An empirical rule for assignment of the absolute configurations of tetra-coordinated pseudo-planar Ni(II) complexes was put forward. Furthermore, a fingerprint was found to judge whether the metallosalen complexes are symmetric or unsymmetric. (C) 2008 Elsevier Ltd. All rights reserved.Project of Innovation Foundation of Xiamen University [XDKJCX20061027]; National NSF of China [20773098, 20572061]; Projects of International Cooperation MOST [2006DFA43030]; Major Program of National Natural Science Foundation of China [20732004

Absolute asymmetric synthesis and resolution mechanism of chiral cis-bromoamminebis(ethylenediamine)cobalt(III) bromide

The absolute asymmetric synthesis of the title complexes Lambda-(+)(D)-cis-[CoBr(NH3)(en)(2)]Br-2(1) and Delta-(-)(D)-cis-[CoBr(NH3)(en)(2)]Br-2(2)(en=1,2-ethylenediamine) as well as the improved optical resolution of cis-[CoBr(NH3)(en)(2)]Br-2.2H(2)O(3) are described in detail. The products were characterized by means of elemental analysis, TG-DTA, optical rotation, UV-Vis, and CD spectra. The distribution of enantiomeric excess(ee) of cis-[CoBr(NH3)(en)(2)]Br-2 in the absolute asymmetric synthesis was obtained by the measurements of their CD spectra. It was found that the complete resolution of rac-cis-[CoBr(NH3)(en)(2)]Br-2.2H(2)O was achieved by use of NH4(d-BCS) (ammonium d-alpha-bromocamphor-pi-sulfonate) or NH4(l-BCS) while NH4(dl-BCS) could only be partially resolved by chiral cis-[CoBr(NH3)(en)(2)]Br-2 at the same condition. It is deduced that there are notable differences in the chiral discrimination of the reciprocal resolution between cis-[CoBr(NH3)(en)(2)]Br-2 and NH4BCS. Moreover, a new "catalysis-crystal induction" mechanism in the preparation of the chiral Co(III) complex is put forward

Synthesis, characterization, structures and magnetic property of chiral oxalate-bridged dicopper(II) complexes

The oxalato-bridged dicopper(II) complexes [Cu-2(mu-ox)(L-RR)(2)(H2O)(2)(ClO4)(2)] (1), [Cu-2(mu-ox)(L-RR)(2)(CH3COCH3)(2)(ClO4)(2)](1a), [Cu-2(mu-ox)(L-SS)(2)(H2O)(2)(ClO4) 2] (2) and [Cu-2(mu-ox)(L-RR)(L-SS)(2)(CH3COCH3)(2)(ClO4)(2)] (3) [L-RR = (8R, 10R)-(-)-[4,5]-pineno-2,2'- bipyridine, L-SS=(8S, 10S)-(+)-[4,5]-pineno-2,2'-bipyridine; ox(2-) = oxalate] were first prepared. A possible mechanism for the formation of the chial dicopper(II) complexes was proposed. Based on elemental analysis, conductance measurement, UV-Vis spectra, CD spectra and X-ray single-crystal diffraction, the oxalato-bridged structures of 1 and 2 were deduced to adopt two Cu(II) ions and the bridged oxalate lying in the nearly same plane. The crystal structures of 1a and 3 reveal that the coordination geometry around each Cu(II) ion is an elongated and distorted octahedron and two axial solvent molecules and two perchlorate ions are anti to each other respectively in both binuclear molecules. The solution CD spectra of 1 and 2 in the visible d-d range show very weak Cotton effects with peaks at 588 and 779 nm, which are approximately of mirror image, suggesting the optical activities may be derived from the vicinal effects of the chiragenic centers at the pinene group of L-RR and L-SS, respectively. Complex 1 has been characterized by variable-temperature magnetic susceptibility and the data was least-square fitted to the Blenaey-Bowers equation. The exchange integral J was found to be. 338.41(4) cm(-1), indicating a strong antiferromagnetic interaction between two copper(II) ions.National Natural Science Foundation of China [20773098, 20973136]; Innovation Foundation of Xiamen University [XDKJCX20061027

pH-Switchable Inversion of the Metal-Centered Chirality of Metallabenzenes: Opposite Stereodynamics in Reactions of Ruthenabenzene with L- and D-Cysteine

We report herein the first study on the chemical interaction between metallabenzenes and bioactive molecules. Due to its unique stereoelectronic activities, a phenanthroline-derived ruthenabenzene [Ru{CHC-(PPh(3))CHC(PPh(3))CH}Cl(C(12)H(8)N(2))-(PPh(3))]Cl(2) (1) selectively binds cysteine in aqueous solution at physiological pH and then undergoes a dynamic inversion of configuration at the Ru center. The structure of the l-cysteine-binding product of 1 has been determined by means of X-ray diffraction. The replacement of the L-cysteine with the D form results in an inverted stereodynamic effect. Furthermore, the inversion process of the Ru-centered configuration could be conveniently controlled by a simple pH adjustment. This is attributed to the significant influence of a special intramolecular electrostatic interaction on the dynamic epimerization process of the cysteine-binding product.National Natural Science Foundation of China[20925208, 20705029, 20773098, 20801046