[Surface roughness characteristics of biological soil crusts and its influencing factors in the hilly Loess Plateau region, China].

Soil surface roughness exerts profound influence on runoff and sediments yield from slopes. Biological soil crusts (BSCs) are ubiquitous living cover in the open spaces between plants in arid and semiarid ecosystems, which considerably impact the surface roughness. Aimed to determine the effect of biological crusts on the surface roughness and its influence factors, this study investigated the surface roughness of soil with BSCs at their different successional stages by using the chain method. Besides, the impacts of slope aspects, soil water content and freezing and thawing on surface roughness were also investigated. Then, the correlations between roughness and soil chemical and physical properties were evaluated. The results showed that soil surface roughness decreased at the initial successional stage of BSCs but increased along with BSCs' development in the region. Soil roughness tended to be stabile since BSCs developed ten years later. The roughness was reduced by 47.0% by the light cyanobacteria-dominated crust and 20.4% by the dark cyanobacteria-dominated crust (moss coverage < 20%), compared with the bare soil. Soil moisture significantly impacted surface roughness. The surface roughness of BSCs changed obviously with soil moisture in the early development, but only slightly in their later succession. Freezing-thawing also affected surface roughness with BSCs. Roughness was more susceptible to freezing-thawing in the early de- velopment of BSCs, with an increase of 29.7% compared with the bare soil. The surface roughness of late successional BSCs exhibited a slight change only after repeated freezing-thawing. The surface roughness of BSCs showed a statistically significant relationship with the coverage of moss (P < 0.1).

[Impact of biological soil crusts on soil water repellence in the hilly Loess Plateau region, China].

By using water drop penetration time (WDPT) and molarity of ethanol droplet (MED) methods, the soil water repellence of undisturbed biological soil crusts (biocrusts) in five successional stages, from the hilly Loess Plateau region of China was tested. The five stages of biocrusts were light cyanobacterial crust, dark cyanobacterial crust, cyanobacterial with sparse moss crust, moss and tiny cyanobacteria patches crust and moss dominated crust. The results showed that 1) the soil water repellence was markedly increased both in the intensity and persistence since the formation of biocrusts. 2) The soil water repellence showed a decrease trend along with the successional stages of biocrusts. The soil water repellence of the biocrusts with the moss coverage above 20% was significantly lower than that of the cyanobacterial crusts. 3) The soil water repellence of the biocrusts was closely related to soil moisture and the dominant organism. The soil water repellence increased with the decrease of soil water content for the moss dominated biocrusts, while changed in a bimodal curve with the decrease of soil water content for the cyanobacterial biocrusts.

Clinical significance of detecting CXC chemotatic factor in early diabetic retinopathy / 中华实验眼科杂志

BackgroundDiabetic retinopathy (DR) is the result of the cytokine network disorders,the imbalance of angiogenic factor and vascular inhibitory factor is the start factor.ObjectiveTo analyze the levels of CXC chemotatic factors of type 2 diabetes mellitus patients,evaluate the clinical application value of them in different clinical types of DR using receiver operating characteristic (ROC)analysis and to approach the new way of individualized treatment.Methods This was a prospective research.The gold standard was ophthalmolscope and fundus fluorescein angiography.The levels of CXC chemotatic factors and multiplicaiton factors were measured in 96 cases with type 2 diabetes mellitus (66 cases with retinopathy and 30 cases without retinopathy as control).The assessment tasks were performed for these index and courses of DR with ROC curve.Results The expression of age,course of disease has significant difference in different courses of DR ( F =8.507,P =0.001 ; F =28.143,P =0.000).Compared with the control group,the expression of growth-related oncogene-α ( GROα ) ( t =- 2.172,P =0.035,AUC =0.625 ),whole blood viscosity 200 ( t =- 3.724,P =0.001,AUC =0.904 ) and neutrophilic leukocyte (t=-2.562,P =0.013,AUC =0.577 ) has significant difference in the group of mild NPDR.Compared with the control group,the expression of interferon-γ-inducible protein 10 ( IP-10 ) ( t =-3.591,P =0.001,AUC =0.592 ),platelet derivation growth factor-BB ( PDGF-BB ) ( t =- 3.233,P =0.003,AUC =0.735 ),vascular endothelial growth factor(VEGF) ( t =- 3.617,P =0.001,AUC =0.776 ),C peptide ( t =- 3.366,P =0.002,AUC =0.962 ),leukocyte ( t=-3.201,P =0.003,AUC =0.852) and neutrophilic leukocyte(t =-4.201,P=0.000,AUC =0.852) has significant difference in the group of moderate and severe NPDR.ConclusionsCXC chemotatic factors may act as reactivator in the pathogenesis of DR,GROα and IP-10 may be useful for clinical monitoring of the severity of DR,and evaluating the imbalance state of chemotatic factors maybe a new approach to clinical monitoring and prognosis of DR.