We show that a perfect quantum state transmission can be realized through a spin chain possessing a commensurate structure of energy spectrum, which is matched with the corresponding parity. As an exposition of the mirror inversion symmetry discovered by Albanese et. al (quant-ph/0405029), the parity matched the commensurability of energy spectra help us to present the novel pre-engineered spin systems for quantum information transmission. Based on the these theoretical analysis, we propose a protocol of near-perfect quantum state transfer by using a ferromagnetic Heisenberg chain with uniform coupling constant, but an external parabolic magnetic field. The numerical results shows that the initial Gaussian wave packet in this system with optimal field distribution can be reshaped near-perfectly over a longer distance.

CeO(2)-TiO(2) (CeTi) catalysts synthesized by an ultrasound-assisted impregnation method were employed to oxidize elemental mercury (Hg(0)) in simulated low-rank (sub-bituminous and lignite) coal combustion flue gas. The CeTi catalysts with a CeO(2)/TiO(2) weight ratio of 1-2 exhibited high Hg(0) oxidation activity from 150 to 250 °C. The high concentrations of surface cerium and oxygen were responsible for their superior performance. Hg(0) oxidation over CeTi catalysts was proposed to follow the Langmuir-Hinshelwood mechanism whereby reactive species from adsorbed flue gas components react with adjacently adsorbed Hg(0). In the presence of O(2), a promotional effect of HCl, NO, and SO(2) on Hg(0) oxidation was observed. Without O(2), HCl and NO still promoted Hg(0) oxidation due to the surface oxygen, while SO(2) inhibited Hg(0) adsorption and subsequent oxidation. Water vapor also inhibited Hg(0) oxidation. HCl was the most effective flue gas component responsible for Hg(0) oxidation. However, the combination of SO(2) and NO without HCl also resulted in high Hg(0) oxidation efficiency. This superior oxidation capability is advantageous to Hg(0) oxidation in low-rank coal combustion flue gas with low HCl concentration.

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Although nitrogenase enzymes routinely convert molecular nitrogen into ammonia under ambient temperature and pressure, this reaction is currently carried out industrially using the Haber-Bosch process, which requires extreme temperatures and pressures to activate dinitrogen. Biological fixation occurs through dinitrogen and reduced NxHy species at multi-iron centres of compounds bearing sulfur ligands, but it is difficult to elucidate the mechanistic details and to obtain stable model intermediate complexes for further investigation. Metal-based synthetic models have been applied to reveal partial details, although most models involve a mononuclear system. Here, we report a diiron complex bridged by a bidentate thiolate ligand that can accommodate HN=NH. Following reductions and protonations, HN=NH is converted to NH3 through pivotal intermediate complexes bridged by N2H3(-) and NH2(-) species. Notably, the final ammonia release was effected with water as the proton source. Density functional theory calculations were carried out, and a pathway of biological nitrogen fixation is proposed.