he analytical technique of trace uranium has been developed rapidly since Robbins firstreported the laser uranium analyzer in 1978. Because of the complicated operation and experimentalprocedure of the normal spectrop...he analytical technique of trace uranium has been developed rapidly since Robbins firstreported the laser uranium analyzer in 1978. Because of the complicated operation and experimentalprocedure of the normal spectrophotometer, neutron activation and solid fluorescence, they havebeen replaced gradually by the laser induced fluoresccncc mcthod. According to high sensitivity andIow detection limit of the fluoreseenee, it can determine the trace uranium. The uranium content inthe lake water, underground water and rain etc. can be measured directly without pretreatment. Therange of the method for determining uranium is from 005 ppb to 20 ppb, and the detection limitis 0.05 ppb.展开更多
目的探讨基质辅助激光解析电离飞行时间质谱(matrix-assisted laser desorption/ionization-time of flight mass spectrometry,MALDI-TOF MS)鉴定临床复合群菌种及常规方法难鉴定菌种的应用价值。方法收集烟台毓璜顶医院2020年1月至202...目的探讨基质辅助激光解析电离飞行时间质谱(matrix-assisted laser desorption/ionization-time of flight mass spectrometry,MALDI-TOF MS)鉴定临床复合群菌种及常规方法难鉴定菌种的应用价值。方法收集烟台毓璜顶医院2020年1月至2021年9月临床分离的153株非重复复合群菌种及常规方法难鉴定菌种,采用MALDI-TOF MS与16SrRNA两种方法进行菌种鉴定。结果以16SrRNA测序鉴定作为金标准,MALDI-TOF MS均可将153株复合群菌种及常规方法难鉴定菌种准确鉴定至属水平,一致性为100%。在种水平鉴定上,143株细菌MALDI-TOF MS鉴定结果与16SrRNA测序鉴定的一致性为93.5%。对于复合群菌种,MALDI-TOF MS鉴定鲍曼不动杆菌复合群、洋葱伯克霍尔德复合群的一致率均为100%,阴沟肠杆菌复合群一致率为50%(6/12),并将6株霍氏肠杆菌中的1株错误鉴定为阿氏肠杆菌,其余5株被错误鉴定成阴沟肠杆菌;对于常规方法难鉴定菌种,凝固酶阴性葡萄球菌属、其他不动杆菌属及其他不常见菌属一致率为100%,诺卡菌属一致率为89.5%,棒状杆菌属一致率为77.8%。2株Appendicis棒状杆菌和弗雷尼棒状杆菌只鉴定到属水平,2株盖尔森基兴诺卡菌鉴定成豚鼠耳炎诺卡菌。结论MALDI-TOF MS在临床复合群菌种及常规方法难鉴定菌种鉴定中具有操作简便、鉴定准确率高的优点,可用于临床微生物实验室对临床复合群菌种及常规方法难鉴定菌种标本的常规鉴定,为临床抗菌药物的使用提供依据。展开更多
Selective laser melting is an additive manufacturing method based on local melting of a metal powder bed by a high power laser beam. Fast laser scans are responsible for severe thermal gradients and high cooling rates...Selective laser melting is an additive manufacturing method based on local melting of a metal powder bed by a high power laser beam. Fast laser scans are responsible for severe thermal gradients and high cooling rates which produce complex hydrodynamic fluid flow. These phenomena affect crystal growth and orientation and are believed to be the cause of material spattering and microstructural defects, e.g. pores and incompletely melted particles. In this work, the microstructure and texture of 316L bars built along two different orientations and the effect of different distribution of defects on their mechanical response and failure mechanisms were investigated. Partially molten powder particles are believed to be responsible for the scattering in elongation to failure, reduced strength, and premature failure of vertical samples.展开更多
The shape and shift of Raman peak of solid organics prove to be capable of revealing atomic and molecular level vibration information of aromatic ring structure and its relationship with sample maturation. Raman "...The shape and shift of Raman peak of solid organics prove to be capable of revealing atomic and molecular level vibration information of aromatic ring structure and its relationship with sample maturation. Raman "D" peaks and "G" peaks of a series of continuously maturated coal samples were measured, and the inter-peak intervals (G-D) and peak height ratios (Dh/Gh) were derived and correlated with the vitrinite reflectance (vRo%) of standard coal samples. As a result, two formulae were established by using the two Raman indices for calculation of Raman reflectance (RmcRo%), which is equivalent to vitrinite reflectance. The formula for calculating Raman reflectance indicative of organic maturation using Raman shift inter-peak interval (G-D) is RmcRo%=0.0537d(G-D)-11.21, which is mainly applicable to matured to highly matured carbonized samples of solid organics; The formula for calculating Raman reflectance indicative of organic maturation using Raman peak height ratio (Dh/Gh) is RmcRo%=1.1659h (Dh/Gh)+2.7588, which is mainly applicable to carbonized samples of solid organics that are over matured or going to be turned into granulated graphite. Preliminary applications indicate that Raman reflectance "RmcRo%" calculated based on results of Raman spectral analysis of solid organics can be used to characterize sample maturation at molecular level, so enjoying extensive prospects in geological applications.展开更多
文摘he analytical technique of trace uranium has been developed rapidly since Robbins firstreported the laser uranium analyzer in 1978. Because of the complicated operation and experimentalprocedure of the normal spectrophotometer, neutron activation and solid fluorescence, they havebeen replaced gradually by the laser induced fluoresccncc mcthod. According to high sensitivity andIow detection limit of the fluoreseenee, it can determine the trace uranium. The uranium content inthe lake water, underground water and rain etc. can be measured directly without pretreatment. Therange of the method for determining uranium is from 005 ppb to 20 ppb, and the detection limitis 0.05 ppb.
文摘Selective laser melting is an additive manufacturing method based on local melting of a metal powder bed by a high power laser beam. Fast laser scans are responsible for severe thermal gradients and high cooling rates which produce complex hydrodynamic fluid flow. These phenomena affect crystal growth and orientation and are believed to be the cause of material spattering and microstructural defects, e.g. pores and incompletely melted particles. In this work, the microstructure and texture of 316L bars built along two different orientations and the effect of different distribution of defects on their mechanical response and failure mechanisms were investigated. Partially molten powder particles are believed to be responsible for the scattering in elongation to failure, reduced strength, and premature failure of vertical samples.
基金supported by the National Basic Research Program of China (2012CB214705)the National Natural Science Foundation of China (41072095)+1 种基金the State Scientific Brainstorm Program (2011ZX05008-002)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-Q05-03 and KZCX2-YW-Q05-06)
文摘The shape and shift of Raman peak of solid organics prove to be capable of revealing atomic and molecular level vibration information of aromatic ring structure and its relationship with sample maturation. Raman "D" peaks and "G" peaks of a series of continuously maturated coal samples were measured, and the inter-peak intervals (G-D) and peak height ratios (Dh/Gh) were derived and correlated with the vitrinite reflectance (vRo%) of standard coal samples. As a result, two formulae were established by using the two Raman indices for calculation of Raman reflectance (RmcRo%), which is equivalent to vitrinite reflectance. The formula for calculating Raman reflectance indicative of organic maturation using Raman shift inter-peak interval (G-D) is RmcRo%=0.0537d(G-D)-11.21, which is mainly applicable to matured to highly matured carbonized samples of solid organics; The formula for calculating Raman reflectance indicative of organic maturation using Raman peak height ratio (Dh/Gh) is RmcRo%=1.1659h (Dh/Gh)+2.7588, which is mainly applicable to carbonized samples of solid organics that are over matured or going to be turned into granulated graphite. Preliminary applications indicate that Raman reflectance "RmcRo%" calculated based on results of Raman spectral analysis of solid organics can be used to characterize sample maturation at molecular level, so enjoying extensive prospects in geological applications.
