Aims Biological soil crusts (BSCs) could improve severe environment ecological conditions by increasing soil moisture, soil nitrogen concentration, and so on. In order to control desertification and recover the destroyed soil fertility utilizing a new means using BSCs, the soil surface was artificially inoculated with Microcoleus vaginatus and Scytonema javanicum. Relationships between the development of the artificially induced biological soil crusts and the distribution and dynamic changes of nitrogen and phosphorus in the soil crusts have been analyzed. Methods Crusts of different ages were investigated by measuring soil physical and chemical factors, such as moisture, pH, total and available N content, and total and available P, which were correlated with the depths of the crusts.

Photocatalytic CO2 reduction to CH4 is a promising strategy to solve the greenhouse effect and energy shortage problems. However, the application has been restricted by the low efficiency and poor...

The intramolecular magnetic interactions in one-electron oxidized iron(iii) porphyrin π-radical cations with planar and saddle conformations have been compared by means of a variety of spectroscopic, physical methods and unrestricted DFT calculations.

Saddle-shaped hemes have been discovered in the structures of most peroxidases. How such a macrocycle deformation affects the reaction of Fe III hemes with hydrogen peroxide (H 2 O 2 ) to form high-valent Fe-oxo species remains uncertain. Through examination of the ESI-MS spectra, absorption changes and 1 H NMR chemical shifts, we investigated the reactions of two Fe III porphyrins with different degrees of saddling deformation, namely Fe III (OETPP)ClO 4 (1 OE ) and Fe III (OMTPP)ClO 4 (1 OM ), with tert-butyl hydroperoxide (tBuOOH) in CH 2 Cl 2 at À 40 °C, which quickly resulted in OÀ O bond homolysis from a highly unstable Fe III -alkylperoxo intermediate, Fe III -O(H)OR (2) into Fe IV -oxo porphyrins (3).Insight into the reaction mechanism was obtained from [tBuOOH]-dependent kinetics. At À 40 °C, the reaction of 1 OE with tBuOOH exhibited an equilibrium constant (K a = 362.3 M À 1 ) and rate constant (k = 1.87 × 10 À 2 s MÀ > 1 ) for the homolytic cleavage of the 2 OÀ O bond that were 2.1 and 1.4 times higher, respectively, than those exhibited by 1 OM (K a = 171.8 M À 1 and k = 1.36 × 10 À 2 s À 1 ). DFT calculations indicated that an Fe III porphyrin with greater saddling deformation can achieve a higher HOMO ([Fe(d z 2 ,d x 2 À y 2 )-porphyrin(a 2u )]) to strengthen the orbital interaction with the LUMO (OÀ O bond σ*) to facilitate OÀ O cleavage.

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