Increased salinity and groundwater levels lead to degradation of the Robinia pseudoacacia forest in the Yellow River Delta

Forest degradation is a worldwide problem,although its causes vary due to geographical and climatic differences and man-made causes.In recent years,the Robinia pseudoacacia forest in the Yellow River Delta has suffered severe degradation.The causative mechanisms were investigated in the field over two years,and the results show that increased forest degradation was reflected by increased tree mortality,high leaf and soil sodium salt levels and groundwater depth.Average tree diameters decreased,and leaf chlorophyll and soil microbial contents decreased.Redundancy discriminate analysis(RDA)showed that degradation of the forest was correlated positively with soil salt content,but negatively with groundwater depth.Correlation analysis showed that 0.79%–0.95%soil salt content and above 1.20 m groundwater depth caused the death of R.pseudoacacia trees due to localized anthropogenic economic activities,such as rice farming,that disrupted the original water–salt balance.Measures are recommended to prevent further degradation and restore degraded forests.

尿囊素促进破骨细胞缺陷斑马鱼骨折修复

骨折愈合是一个由多细胞介导的多步骤的严密有序的过程,其中破骨细胞介导的骨重塑在骨折愈合中具有关键作用,其生成减少或者功能障碍不仅导致骨折的易发生,还会引起骨折愈合障碍。但是,目前关于破骨细胞缺陷所致的骨折愈合障碍的研究较少,并且临床上尚缺乏针对破骨细胞缺陷所致骨折愈合障碍的治疗药物。斑马鱼(Danio rerio)骨骼系统中的细胞类型和调节途径与哺乳动物高度相似,使得其被广泛地运用于骨骼相关的研究。为了研究破骨细胞缺陷所致的骨折愈合障碍过程以及寻找有潜力的治疗药物,本研究使用前期建立的fms基因突变斑马鱼(fmsj4e1)构建了体内破骨细胞缺陷骨折模型,结果发现功能性破骨细胞减少可在骨折早期影响骨折的愈合;使用离体鳞片培养系统用于筛选破骨细胞靶向药物,获得了可以激活破骨细胞的小分子化合物尿囊素(allantoin,ALL);随后,在体内fmsj4e1骨折缺陷模型中验证了ALL对破骨细胞的激活作用以及对骨折修复的促进作用;最后,通过对破骨细胞生成和成熟过程的分析,发现ALL可能通过调节RANKL/OPG来促进破骨细胞的成熟,从而促进fmsj4e1骨折愈合。本研究为未来改善破骨细胞缺陷引起的骨折愈合障碍提供了潜在的新方法。

The Comprehensive Benefits about Under-forest Economy in Shijiazhuang City

Based on the relevant domestic and foreign theories,we establish the evaluation indicator system for the comprehensive benefits about under-forest economy. Using the data from 2010 to 2014,we employ AHP to measure the comprehensive benefits of under-forest economy,and convert the comprehensive benefits into the data that can be used for analysis and comparison. It is found that the comprehensive benefit index of under-forest economy in Shijiazhuang City continued to increase from 2010 to 2014(0.223,0.515,0.523,0.698 and 0.956,respectively). This further indicates that the under-forest economy in Shijiazhuang City shows a good trend towards the goal of high quality and efficiency,so it is a correct model of development. Based on the results and the problems during the research process,some policy recommendations are brought forward for the development of under-forest economy.

Microstructure and Mechanical Properties of Nickel‑Aluminum Bronze Coating on 17‑4PH Stainless Steel by Laser Cladding

Bimetallic copper-steel composite could be an effective structural material to improve the performance of traditional nickel-aluminum bronze(NAB)ship propeller due to its high structural strength and corrosion resistance.In this work,the defect-free NAB coatings has been successfully fabricated by laser direct depositing technique on the 17-4PH stainless steel substrate.The phase constitution,microstructure characteristics and hardness properties were investigated in details.The XRD results showed that the coatings mainly consisted ofα-Cu,Fe and intermetallicκphases despite the diffraction peaks shifted more than 0.5°,which may due to the influence of the Ni,Fe and Al atoms dissolved into Cu-matrix.The microstructures of the coatings were affected significantly by laser energy density according to SEM and EDS results.The top region of the coating was more undercooled during solidification,therefore the grains at this region was much finer than that at the bottom region.The higher energy input would lead to coarser grains.Fe-rich dendrites and spherical particles were found in the Cu matrix,which could be a result of liquid separation.The hardness of the coating is in the range of 204 HV0.2–266 HV0.2 which is higher than traditional as-cast NAB.The uneven distribution of Fe-rich phases as well as the hardκphases could be the main reasons for the fluctuations of the hardness value.Tensile fracture occurred at bronze side,not at transition zone,which shows there is a good interfacial bonding between the two metals produced by laser cladding.

The synergistic role of Pu.1 and Fms in zebrafish osteoclast-reducing osteopetrosis and possible therapeutic strategies

Osteoclasts are bone resorption cells of myeloid origin. Osteoclast defects can lead to osteopetrosis, a genetic disorder characterized by bone sclerosis for which there is no effective drug treatment. It is known that Pu.1 and Fms are key regulators in myelopoiesis, and their defects in mice can lead to reduced osteoclast numbers and consequent osteopetrosis. Yet how Pu.1 and Fms genetically interact in the development of osteoclasts and the pathogenesis of osteopetrosis is still unclear. Here, we characterized pu.1^(G242) D;fms^(j4e1) double-deficient zebrafish, which exhibited a greater deficiency of functional osteoclasts and displayed more severe osteopetrotic symptoms than the pu.1^(G242) Dor fms^(j4e1) single mutants, suggesting a synergistic function of Pu.1 and Fms in the regulation of osteoclast development. We further demonstrated that Pu.1 plays a dominant role in osteoclastogenesis, whereas Fms plays a dominant role in osteoclast maturation. Importantly, treatment with the drug retinoic acid significantly relieved the different degrees of osteopetrosis symptoms in these models by increasing the number of functional osteoclasts. Thus, we report the development of valuable animal models of osteopetrosis, and our results shed light on drug development for antiosteopetrosis therapy.