Protonated and deprotonated vanadyl imidazole tartrates for the mimics of the vanadium coordination in the FeV-cofactor of V-nitrogenase.

Chiral imidazole-based oxidovanadium tartrates (Him)[Δ,Λ-VIV2O(,-Htart)(,-tart)(Him)]·Him (1, Htart = tartaric acid, Him = imidazole) and [Λ,Λ-VIV2O(,-tart)(Him)]·4HO (2) and their corresponding enantiomers (Him)[Λ,Δ-VIV2O(,-Htart)(,-tart)(Him)]·Him (3) and [Δ,Δ-VIV2O(,-tart)(Him)]·4HO (4) were obtained in alkaline solutions. Interestingly, the tartrates chelate with vanadium bidentately through α-alkoxy/α-hydroxy and α-carboxy groups and imidazole coordinates monodentately through nitrogen atom. It is worth noting that complexes 1 and 3 contain both protonated α-hydroxy and deprotonated α-alkoxy groups simultaneously, which have short V-O distances [1.

The inhibitory effect of mixotrophic Ochromonas gloeopara on the survival and reproduction of Daphnia similoides sinensis.

Mixotrophs account for a high proportion (occasionally up to 80%) of the phytoplankton biomass. Chrysophyte is one major component of mixotrophs. Because of their possible toxicity and linkage between microbial community and higher trophic levels, the effect of mixotrophic golden algae on potential grazers received much attention.

Radiometer-to-imager in-flight cross calibration and verification.

This work develops a method to complete the in-flight cross calibration and verification between a radiometer and an imager hosted on aircraft. The in-flight cross calibration is data transmission through time matching, space matching, and spectral matching of two polarization instruments on the same platform, and this method can not only complete the data transfer without considering the surface type to reduce the calibration cycle but also can obtain huge and rich calibration data. The radiometer is the particulate observing scanning polarimeter (POSP), which takes multi-angle, photo-polarimetric measurements in several spectral channels.

Bond-valence analyses of the crystal structures of FeMo/V cofactors in FeMo/V proteins.

The bond-valence method has been used for valence calculations of FeMo/V cofactors in FeMo/V proteins using 51 crystallographic data sets of FeMo/V proteins from the Protein Data Bank. The calculations show molybdenum(III) to be present in MoFeSC(Cys)(HHis)[R-(H)homocit] (where Hhomocit is homocitric acid, HCys is cysteine and HHis is histidine) in FeMo cofactors, while vanadium(III) with a more reduced iron complement is obtained for FeV cofactors. Using an error analysis of the calculated valences, it was found that in FeMo cofactors Fe1, Fe6 and Fe7 can be unambiguously assigned as iron(III), while Fe2, Fe3, Fe4 and Fe5 show different degrees of mixed valences for the individual Fe atoms.