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991.
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建立原子尺度模拟三维立方晶格纳米单晶金属固体力学行为的物理模型,基于修正的镶嵌原子势,采用分子动力学方法分析面心立方晶格(FCC)镍和体心立方晶格(BCC)α-铁三维纳米单晶固体在拉伸和剪切载荷作用下的变形破坏,得到两种不同立方晶格三维纳米单晶固体的力学性能,与实验现象和结果吻合。研究表明晶格结构影响纳米晶固体的拉伸变形机制,FCC纳米单晶固体的拉伸变形以定向滑移为主,拉伸破坏存在短暂屈服阶段,有明显弹性模量软化现象;BCC纳米单晶固体的拉伸变形出现原子堆垛,存在较长屈服阶段,延性高于FCC纳米固体,而弹性模量小于后者。FCC纳米单晶固体的剪切模量小于拉伸模量,剪切强度小于拉伸强度,BCC纳米固体则相反。 相似文献
994.
995.
某低品位银铅锌多金属硫化矿石含银74 g/t、铅0.36%、锌0.82%。银矿物以脆银矿和辉银矿为主,铅矿物以方铅矿为主,锌矿物以闪锌矿为主,主要脉石矿物为石英,其次是白云母、绿泥石和钾长石。矿石中银铅锌矿物均部分被氧化,大部分铅锌矿物嵌布粒度较粗,少部分嵌布粒度微细,银在铅、锌、硫等矿物中均有分布,且嵌布粒度较细。为确定矿石的选矿工艺,进行了选矿试验研究。结果表明,矿石在磨矿细度为-0.074 mm占55%的情况下,采用银铅混浮再浮锌最后选硫工艺处理矿石,可获得含银8 515 g/t、含铅51.64%、含锌4.61%、银回收率42.41%、铅回收率56.04%、锌回收率2.15%的银铅精矿,含锌45.47%、含银1 692 g/t、含铅3.48%、锌回收率69.63%、银回收率27.71%、铅回收率12.42%的锌精矿,以及含硫43.79%、含银781 g/t、硫回收率10.56%、银回收率5.63%的硫精矿。 相似文献
996.
建立了高效分离高铀镎比样品中微量镎的方法。采用TEVA-TEVA萃取色层柱分离铀产品中微量镎,经3.0 mol/L HNO3淋洗过后以0.5 mol/L (NH4)2CO3洗脱TEVA树脂上的镎,加入HNO3分解洗脱液中的碳酸镎酰离子并将溶液调至3.0 mol/L HNO3,进行TEVA柱二次分离,最后采用0.02 mol/L HNO3-0.02 mol/L HF洗脱。结果表明:该法稳定性较好,测量相对标准偏差优于4%(n=3),镎的平均回收率大于86%,铀的去污因子大于105,适用于高铀镎比样品中微量镎的分离,在乏燃料后处理工艺中铀线尾端的微量镎分析中具有较好的应用前景。 相似文献
997.
Anna Gazka Anna Marzec-Grzdziel Milan Varsadiya Jacek Nied
wiecki Karolina Gawryjoek Karolina Furtak Marcin Przyby Jarosaw Grzdziel 《International journal of molecular sciences》2022,23(5)
The formation of specific features of forest habitats is determined by the physical, chemical, and biological properties of the soil. The aim of the study was to determine the structural and functional biodiversity of soil microorganisms inhabiting the bulk soil from the peri-root zone of three tree species: Alnus glutinosa, Betula pendula, and Pinus sylvestris. Soil samples were collected from a semi-deciduous forest located in an area belonging to the Agricultural Experimental Station IUNG-PIB in Osiny, Poland. The basic chemical and biological parameters of soils were determined, as well as the structural diversity of bacteria (16S ribosomal RNA (rRNA) sequencing) and the metabolic profile of microorganisms (Biolog EcoPlates). The bulk soils collected from peri-root zone of A. glutinosa were characterized by the highest enzymatic activities. Moreover, the highest metabolic activities on EcoPlates were observed in bulk soil collected in the proximity of the root system the A. glutinosa and B. pendula. In turn, the bulk soil collected from peri-root zone of P. sylvestris had much lower biological activity and a lower metabolic potential. The most metabolized compounds were L-phenylalanine, L-asparagine, D-mannitol, and gamma-hydroxy-butyric acid. The highest values of the diversity indicators were in the soils collected in the proximity of the root system of A. glutinosa and B. pendula. The bulk soil collected from P. sylvestris peri-root zone was characterized by the lowest Shannon’s diversity index. In turn, the evenness index (E) was the highest in soils collected from the P. sylvestris, which indicated significantly lower diversity in these soils. The most abundant classes of bacteria in all samples were Actinobacteria, Acidobacteria_Gp1, and Alphaproteobacteria. The classes Bacilli, Thermoleophilia, Betaproteobacteria, and Subdivision3 were dominant in the B. pendula bulk soil. Streptosporangiales was the most significantly enriched order in the B. pendula soil compared with the A. glutinosa and P. sylvestris. There was a significantly higher mean proportion of aerobic nitrite oxidation, nitrate reduction, sulphate respiration, and sulfur compound respiration in the bulk soil of peri-root zone of A. glutinosa. Our research confirms that the evaluation of soil biodiversity and metabolic potential of bacteria can be of great assistance in a quality and health control tool in the soils of forested areas and in the forest production. Identification of bacteria that promote plant growth and have a high biotechnological potential can be assume a substantial improvement in the ecosystem and use of the forest land. 相似文献
998.
999.
通过铜模吸铸法获得直径为2mm的Fe61Co10Zr5W4B20块体非晶合金.采用X射线衍射(XRD)、示差扫描量热(DSC)、显微硬度及压缩试验等方法研究了非晶合金的结构、热稳定性,特别是等温热处理对其显微硬度与压缩强度的影响.结果表明,Fe61Co10Zr5W4B20非晶合金的显微硬度为1207HV0.2,压缩强度σbc为1707.6MPa.当等温热处理温度低于晶化起始温度时,硬度不随热处理时间的增长而变化;但在高于晶化峰值温度时,硬度值随时间变化先升后降.在热处理时间相同的条件下,随着处理温度的升高,合金的硬度增大,但压缩强度会逐步减小. 相似文献
1000.
《钢铁研究学报(英文版)》2016,(1):42-47
The metallic glass matrix composites(MGMCs)and bulk metallic glasses(BMGs)were studied by statistical analysis during plastic deformation at the strain rates of 2×10~(-2),2×10~(-3),and 2×10~(-4) s~(-1),respectively.No serration events occur in both MGMCs and BMGs during compression tests at the strain rate of 2×10~(-2) s~(-1).When deformed at the strain rate of 2×10~(-3) s~(-1),the BMG displays a larger plasticity,which is due to the larger serration events followed by a series of small serrations caused by the continuous movement of free volume.The amplitudes and elastic-energy densities increase with increasing the strain rates owing to many serrations in MGMCs.It is deduced that the Young′s modulus decreases from the normalized stress drop and fluctuations are observed on stressstrain curves,which is attributed to a lower coefficient according to the stick-slip model. 相似文献