No abstract

The relaxation of amorphous materials, i.e., aging, would largely endanger their performances in service. Here we report a mechanical relaxation-to-rejuvenation transition of a Zr35Ti30Be27.5Cu7.5 bulk metallic glass (BMG) in elastostatic compression at ambient temperature, thus provide an accessible way to tailor the mechanical properties of amorphous materials. To unravel the structural evolution underlying the observed transition, atomistic simulations parallel with the experimental tests on a typical model glass system Zr60Cu40 were performed, which successfully reproduced and thus upheld the experimentally observed mechanical relaxation-to-rejuvenation transition. The variations of coordination number and atomic volume during the transition are evaluated to indicate a de-mixing tendency of the constituent atoms in the rejuvenation stage. This de-mixing tendency largely explains the difference between mechanical rejuvenation and thermal rejuvenation and reveals a competitive relationship between activation enthalpy and activation entropy in the stress-driven temperature-assisted atomic dynamics of BMG, such as diffusion and plastic deformation etc.

No abstract

The Dongting Lake region is one of the areas prone to flood disaster in China. Despite the frequent occurrence of flooding in this area, few studies have analysed its effects on rodent communities, especially their recovery after withdrawal of floodwaters. We carried out a study of rodent recovery after flooding of the Dongting Lake region in 1998. Rodent population monitoring in the flooded countryside of the Dongting Lake region was conducted during 1998-2001. The census was conducted in Anzao polder of Anxian County in Hunan Province, where the dike burst in 1998 and thousands of hectares of farmland were flooded from July to October. The results indicate that flood disaster could provide important changes in rodent community structure. Firstly, species abundance in the post-flood area became less than in the normal area. Striped field mice Apodemus agrarius colonized the flooded area in farmland until March 2000, and Norway rats Rattus norvegicus and house mice Mus musculus occurred in July and December 2000, respectively. The degree of the effect on the rodent community in residential premises is less than that in farmland. However, the rodent community in the flooded area could recover and become similar to the normal community. The recovery of rodent species composition was faster in residential premises than in farmland after flooding. Secondly, there was a similar tendency of the dominant concentration indices between post-flood and normal areas. Thirdly, inundation for a long period could reduce the species diversity of the rodent community in farmland. The significant difference in abundance was continued to 2000 in postflooded farmland; however, the influence on the rodent community in residential premises was less and their diversity indices did not differ in 1999. Similarity indices indicated that variation between post-flood and normal areas had been gradually becoming low from 1999 to 2001. Finally, the monitoring data showed that rodent populations in the flooded area were less than those in the normal area in the first step after withdrawal of floodwaters. However, the rodent population increased rapidly in the flooded area, and became greater than that in the unflooded area in half a year. The population in the flooded area also increased faster than that in unflooded neighbouring area after the application of rodenticide. Another phenomenon was that the population density of rodents could reach levels greater than the normal area, and may continue for more than 2 years. Flood disasters could reduce population densities and species abundance, species diversity and evenness, while increasing dominant concentration indices of the rodent community. However, after 3 years, the rodent community structure became similar to that in the non-flooded area, except for high density. The recovery of rodent communities in residential premises was faster than that in farmland for a lesser degree of flooding.

No abstract

Abstract. An experiment was conducted to study the influences of nitrification inhibitor (NI) and biochar incorporation on yield-scaled N 2 O using the static chamber method and gas chromatography in an intensively managed vegetable field with seven consecutive vegetable crops from 2012 to 2014 in southeastern China. With an equal annual nitrogen (N) application rate (1217 kg N ha −1 yr −1 ), six treatments under three biochar amendment rates -namely, 0 t ha −1 (C0), 20 t ha −1 (C1) and 40 t ha −1 (C2) -with compound fertilizer (CF) or urea mixed with NI of nitrapyrin as chlorinated pyridine (CP) were studied in these field experiments. The results showed that, although there was no significant influence on soil organic carbon (SOC) content or total nitrogen (TN), nitrapyrin could result in a significant increase in soil pH during the experimental period. Nitrapyrin significantly decreased cumulative N 2 O emissions by 15.9-32.1 % while increasing vegetable yield by 9.8-41.9 %. Thus, it also decreased yield-scaled N 2 O emissions significantly. In addition to the differential responses of the soil pH, biochar amendment significantly increased SOC and TN. Compared with the treatments without biochar addition, the cumulative N 2 O emissions showed no significant difference in the CF or the CP group treatments but increased slightly (not significantly) by 7.9-18.3 % in the CP group treatments. Vegetable yield was enhanced by 7.1-49.5 % in the CF group treatments compared with the treatments without biochar amendment, while there was no significant difference in the CP group treatments, and the yield-scaled N 2 O emissions were thus decreased significantly. Furthermore, treatments involving with nitrapyrin and biochar incorporation slightly increased yieldscaled N 2 O emissions by 9.4 %, on average, compared with CP-C0. Therefore, the application of nitrapyrin could serve as an appropriate practice for increasing vegetable yield and mitigating N 2 O emissions in intensively managed vegetable fields and should be further examined in various agroecosystems.

No abstract

Femoral head necrosis (FHN) is a common disorder in fast-growing broilers in the poultry industry, but the pathogenesis of FHN has not been clarified completely. In the present study, glucocorticoid (GC) administration was used to induce FHN in broilers. Compared with normal birds, histopathology showed that the length of the articular cartilage of GC-induced FHN broilers was thicker while the proliferative zone and prehypertrophic zone were obviously thinner. Moreover, hematoxylin and eosin (HE) staining showed the apoptotic chondrocyte in the growth plate of the femoral head in FHN-affected birds. Bone parameters also decreased significantly in GC-induced FHN broilers. In addition, as for the mRNA expression, GC-induced FHN broilers had an apparent reduction in Col-II, Col-X, and Bcl-2 but a significant promotion of Caspase-3, Caspase-9, ASK-1, and JNK-1 when compared with the normal birds. It showed glucocorticoid induced FHN in broilers by affecting the proliferation, differentiation, and apoptosis of chondrocytes accompanying the retarding of bone growth.