catena-Poly[[[diaqua­diformato­cobalt(II)]-μ-1,4-bis­(1H-benzimidazol-1-yl)benzene] dihydrate]

In the title coordination polymer, {[Co(CHO2)2(C20H14N4)(H2O)2]·2H2O}n, the CoII atom (site symmetry ) is coordinated by two formate O atoms, two water O atoms and two N atoms from two 1,4-bis­(1H-benzimidazol-1-yl)benzene ligands (L), resulting in a distorted trans-CoN2O4 octa­hedral coordin­ation environment. The complete L ligand is generated by crystallographic inversion symmetry and serves to bridge the cobalt ions into a chain propagating in [1 ]. The dihedral angle between the central benzene ring and the imidazole ring system is 38.48 (12)°. O—H⋯O hydrogen bonds involving both the coordinated and uncoordinated water mol­ecules occur and help to link the chains together

Responses of Community Structure, Productivity and Turnover Traits to Long-Term Grazing Exclusion in a Semiarid Grassland on the Loess Plateau of Northern China

Grazing exclusion has been widely used for restoration of degraded grassland all over the world. Based on over a 30-year (from 1982 to 2011) vegetation survey and a 2-year (from 2013 to 2014) field decomposition experiment in Yunwu Mountain Grassland Nature Reserve on the Loess Plateau of China, responses of community structure and productivity and decomposition traits of dominant Stipa species (Stipa bungeana, Stipa grandis and Stipa przewalskyi) litters were determined to reveal the ecosystem cyclic process. Results showed that grassland coverage, plant density, Shannon-Wiener index and aboveground productivity changed in a hump pattern with peaks in 2002. Productivity was significantly positively correlated with mean annual temperature. The direction and magnitude about effects of climatic changes on productivity depended on phonological stages of plant community. Warming in early stage of growing season (April–May) contributed the increase of productivity, while temperature rise after the growing season (September–March in the next following year) was negatively correlated with productivity in the following year. Leaf litters of three Stipa species (S. bungeana, S. grandis and S. przewalskyi) had higher decomposition rates in the growing season than that in the nongrowing season. Nutrient-releasing pattern in litters of three Stipa species followed a different pattern: S. bungeana > S.grandis>S. przewalskyi. Considering productivity and decomposition traits, grazing exclusion promotes carbon sequestration of semiarid grassland, while adjustments in nutrient cycling might explain fluctuations of community structure

Effect of congenital ptosis on astigmatism and axis length

AIM: To investigate the effects of congenital ptosis degree on total astigmatism, corneal astigmatism, intraocular astigmatism and axis length, and to discuss the relation with amblyopia. <p>METHODS: Fifty patients(100 eyes)with congenital ptosis were selected and divided into four groups: 33 eyes in group Ⅰ(normal); 20 eyes in group Ⅱ(mild); 17 eyes in group Ⅲ(moderate); 30 eyes in group Ⅳ(severity). Firstly, they received standardized medical optometry. Absolute value of astigmatism was recorded as total astigmatism. Then, corneal topography was used to measure double eyes for at least 3 times, and the best results were used to record the SimK. Define absolute value of △SimK as corneal astigmatism. Finally, axial length was measured for 5 times by A super-measurement, and take the mean value. Formula: intraocular astigmatism=total astigmatism-corneal astigmatism.<p>RESULTS: There was a significance difference between total astigmatism and cornea astigmatism(<i>P</i>=0.000, 0.002<0.05). Also they were positive correlation with severity of ptosis(Spearman <i>r</i>_s=0.514, 0.721,<i>P</i><0.05), but there was not significance difference in axial orientation, intraocular astigmatism and axial length(all <i>P</i>>0.05). The axial orientation, intraocular astigmatism had no correlation with severity of ptosis.<p>CONCLUSION: The congenital ptosis affects on eye astigmatism through the change of cornea astigmatism, which is related to severity of ptosis, but has no effect on axial length. The rate of amblyopia is higher than normal on congenital ptosisespecially severity. Amblyopia is related to high astigmatism which is moderate astigmatism with rule