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In order to achieve the mass production of the brazing diamond tools, brazing of diamond grains to the matrix using Ni Cr active filler alloy was investigated in the mesh belt furnace, which could realize uninterrupted brazing under ammonia dissociating atmosphere. The surface characteristics and interfacial microstructures of brazed diamond in mesh belt furnace were analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The residual stress, static compressive strength and impact toughness of the brazing diamond were measured and the corresponding results were compared to the brazing diamond grains in vacuum furnace. Results demonstrated that chemical reaction occurred between the diamond and filler alloy. The compound composed of Cr 3 C 2 and Cr 7 C 3 was formed at diamond interface and a higher bonding strength was obtained. The residual stresses of brazing diamond in mesh belt furnace were lower than that in vacuum furnace in the case of identical protruding height. However the static compressive strength and the impact toughness were higher than that in vacuum furnace. [ABSTRACT FROM AUTHOR]

Abstract: Geographic variation in life history traits has been extensively studied along latitudinal and altitudinal clines, but life history variation among geographically close populations has received much less attention. We collected gravid female toad-headed lizards (Phrynocephalus przewalskii) and environmental data from three localities (Alxa Zuoqi, Alxa Youqi, and Shandan) across the Gobi desert in China, to examine among-population differences in reproductive strategies. The precipitation was significantly lower in Alxa Youqi than Alxa Zouqi and Shandan. Food availability was highest in Shandan, lowest in Alxa Zuoqi, with Alxa Youqi in between. Females from Shandan population were larger and produced more and larger eggs than their counterparts from the other two populations. Incubation period also differed among the populations, with the lowest incubation period in Alxa Youqi population, and the longest incubation period in Alxa Zuoqi population. Our data on the physiological mechanisms of incubation period indicated that the shortened incubation period in Alxa Youqi population was due to advanced embryogenesis completed prior to oviposition rather than higher embryonic heart rates during incubation. Therefore, our data support the hypothesis that geographically close populations can show different reproductive strategies if environmental factors vary among these populations. [Copyright &y& Elsevier]