The microstructure of Fe-Ni metallic phases in Dong Ujimqin mesosiderite was studied using the field emission SEM. Taenite is characterized by a zoned structure, consisting of outer clear taenite and inner cloudy zone...The microstructure of Fe-Ni metallic phases in Dong Ujimqin mesosiderite was studied using the field emission SEM. Taenite is characterized by a zoned structure, consisting of outer clear taenite and inner cloudy zone (CZ). CZ has a typical 'island-honeycomb' microstructure. The average size of the island phase is about 358 nm, suggesting a cooling rate of～0.5℃/Ma at low temperature (【400℃). The Ni concentration profiles across kamacite and zoned taenite were also measured by electron probe microscope analysis (EPMA). Formation of the Fe-Ni metallic phases, microstructure in Dong Ujimqin mesosiderite was discussed based on the new low-temperature Fe-Ni phase diagram.展开更多
扫描电镜具有分辨率高、信号稳定、操作简便等优点,可观察试样的微观形貌,在材料测试中起着重要的作用。扫描电镜主要由真空系统、电子光学系统、显示系统以及附属设备等组成。随着科技的不断发展,扫描电镜变得越来越普及,多数操作人员...扫描电镜具有分辨率高、信号稳定、操作简便等优点,可观察试样的微观形貌,在材料测试中起着重要的作用。扫描电镜主要由真空系统、电子光学系统、显示系统以及附属设备等组成。随着科技的不断发展,扫描电镜变得越来越普及,多数操作人员缺乏系统性的培训,操作水平参差不齐,对设备维护方面不够了解。以FEI Nova NanoSEM 450型场发射扫描电镜为例,介绍了该设备的一系列科学管理与规范操作方法,以期为相关操作人员提供参考。展开更多
The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E ...The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E 1050-12.The Creality Ender-3,a 3D printer,was used for printing the honeycomb structures,and polylactic acid(PLA)material was employed for their construction.The organic,inorganic,and polymeric compounds within the composites were identified using fourier transformation infrared(FTIR)spectroscopy.The structure and homogeneity of the samples were examined using a field emission scanning electron microscope(FESEM).To determine the sound absorption coefficient of the 3D printed honeycomb structure,numerous samples were systematically developed using central composite design(CCD)and analysed using response surface methodology(RSM).The RSM mathematical model was established to predict the optimum values of each factor and noise reduction coefficient(NRC).The optimum values for an NRC of 0.377 were found to be 1.116 wt% carbon black,1.025 wt% aluminium powder,and 3.151 mm distance between parallel edges.Overall,the results demonstrate that a 3Dprinted honeycomb structure filled with nanofillers is an excellent material that can be utilized in various fields,including defence and aviation,where lightweight and acoustic properties are of great importance.展开更多
目的研究一种表征可吸收胶原蛋白材料微观形貌的方法,并分析其孔隙率和孔径。方法利用场发射扫描电子显微镜(Scanning Electron Microscope,SEM),在不同的加速电压下对未喷金样品和喷金样品进行拍摄,使用Image J软件对所得的SEM图像的...目的研究一种表征可吸收胶原蛋白材料微观形貌的方法,并分析其孔隙率和孔径。方法利用场发射扫描电子显微镜(Scanning Electron Microscope,SEM),在不同的加速电压下对未喷金样品和喷金样品进行拍摄,使用Image J软件对所得的SEM图像的孔隙率和孔径进行分析,并对结果的有效性进行验证。结果样品未喷金时使用低倍加速电压可获得清晰的SEM图像;样品喷金后其耐受电压能力明显提高,即使在较高的加速电压下依然能获得清晰的SEM图像。使用Image J软件可对拍摄的SEM图像的孔径和孔隙率进行分析,其中,平均孔隙率为50.9%,平均孔径为11.9μm;孔隙率离散系数为8.6%,孔径离散系数6.7%。结论场发射SEM结合Image J软件是一种表征可吸收胶原蛋白材料孔结构的有效方法,可解决相关标准中方法缺失的问题。展开更多
Our research introduces a groundbreaking chemical reduction method for synthesizing silver nanoparticles, marking a significant advancement in the field. The nanoparticles were meticulously characterized using various...Our research introduces a groundbreaking chemical reduction method for synthesizing silver nanoparticles, marking a significant advancement in the field. The nanoparticles were meticulously characterized using various techniques, including optical analysis, structural analysis, transmission electron microscopy (TEM), and field-emission scanning electron microscope (FESEM). This thorough process instills confidence in the accuracy of our findings. The results unveiled that the silver nanoparticles had a diameter of less than 20 nm, a finding of great importance. The absorption spectrum decreased in the peak wavelength range (405 - 394 mm) with increasing concentrations of Ag nanoparticles in the range (1 - 5%). The XRD results indicated a cubic crystal structure for silver nanoparticles with the lattice constant (a = 4.0855 Å), and Miller indices were (111), (002), (002), and (113). The simulation on the XRD pattern showed a face center cubic phase with space group Fm-3m, providing valuable insights into the structure of the nanoparticles.展开更多
Tamusu mudstone formation, located in the Alxa area in western Inner Mongolia, is considered a potential host formation for high-level radioactive waste(HLW) underground disposal in China. In this study, complementary...Tamusu mudstone formation, located in the Alxa area in western Inner Mongolia, is considered a potential host formation for high-level radioactive waste(HLW) underground disposal in China. In this study, complementary analyses with X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), mercury intrusion porosimetry(MIP), and N_(2) physisorption isotherm were conducted on the Tamusu mudstone to characterize its physical characteristics and microstructural features, such as mineral compositions and pore structure. Several minerals, including carbonates, feldspar, clays and analcime, were identified in Tamusu mudstone by XRD. Images from FE-SEM show that pores in the Tamusu mudstone were dominantly on nanometer scale and generally located within their mineral matrix or at the interface with non-porous minerals. The combination of the MIP and N_2 physisorption curves indicated that the Tamusu mudstone has diverse pore sizes, a porosity varying from 2.34% to 2.84%, and a total pore volume in the range of 0.0065—0.0222 cm^(3)/g with the average pore diameter ranging from 9.6 nm to 19.23 nm. The specific surface area measured by MIP(2.572—5.861 m^(2)/g) was generally higher than that by N_(2) physisorption(1.29—3.04 m^(2)/g), due to the pore network effect, pore shape(e.g. ink-bottle shape), or technique limits. The results related to pore information can be applied as an input in the future to model single-or multi-phase fluid flow and the transport of radionuclides in porous geomedium by migration and diffusion.展开更多
The analysis of gunshot residue(GSR) has played an integral role within the legal system in relation to shooting cases. With a characteristic elemental composition of lead, antimony, barium, and a typically discrimina...The analysis of gunshot residue(GSR) has played an integral role within the legal system in relation to shooting cases. With a characteristic elemental composition of lead, antimony, barium, and a typically discriminative spheroidal morphology, the presence and distribution of GSR can aid in firearm investigations. In this experiment, three shots of low velocity rim-fire ammunition were fired over polished silicon collection substrates placed at six intervals over a 100 cm range. The samples were analysed using a Field Emission Gun Scanning Electron Microscope(FEG-SEM) in conjunction with an X-flash Energy Dispersive X-ray(EDX) detector, allowing for GSR particle analyses of composition and structure at the sub-micron level. The results of this experiment indicate that although classic spheroidal particles are present consistently throughout the entire range of samples their sizes vary significantly, and at certain distances from the firearm particles with an irregular morphology were discerned, forming "impactdisrupted" GSR particles, henceforth colloquially referred to as "splats". Upon further analysis, trends with regards to the formation of these splat particles were distinguished. An increase in splat frequency was observed starting at 10 cm from the firearm, with 147 mm^(-2) splat density, reaching a maximal flux at 40 cm(451 mm^(-2)), followed by a gradual decrease to the maximum range sampled. Moreover, the structural morphology of the splats changes throughout the sampling range. At the distances closest to the firearm, molten-looking particles were formed, demonstrating the metallic residues were in a liquid state when their flight path was disrupted. However, at increased distances-primarily where the discharge plume was at maximum dispersion and moving away from the firearm, the residues have had time to cool in-fight resulting in semi-congealed and solid particles that subsequently disrupted upon impact, forming more structured as well as disaggregated splats. The relative compositions of the characteristic elements that are present in GSR also change in the different splat morphologies sampled,which may contribute to the particles' physical structures. Two distinct populations of splats were also observed: circular and elongated, which suggest the residues hit the substrate at different angles. The difference in the splat impact angle can be ascribed to the position of the residues within the firearm discharge plume; particles get caught up in the vortex that is created by the discharge gases behind the projectile as it leaves the barrel, thereby affecting their directionality and flight time. This reasoning could also justify the existence of both spheroidal and splat particles at certain distances. The novel sampling and analytical techniques used in this experiment have provided previously unknown information in relation to GSR structure and formation which could have greater implications to its current analysis amongst laboratories and law enforcement agencies worldwide.展开更多
文摘The microstructure of Fe-Ni metallic phases in Dong Ujimqin mesosiderite was studied using the field emission SEM. Taenite is characterized by a zoned structure, consisting of outer clear taenite and inner cloudy zone (CZ). CZ has a typical 'island-honeycomb' microstructure. The average size of the island phase is about 358 nm, suggesting a cooling rate of～0.5℃/Ma at low temperature (【400℃). The Ni concentration profiles across kamacite and zoned taenite were also measured by electron probe microscope analysis (EPMA). Formation of the Fe-Ni metallic phases, microstructure in Dong Ujimqin mesosiderite was discussed based on the new low-temperature Fe-Ni phase diagram.
文摘扫描电镜具有分辨率高、信号稳定、操作简便等优点,可观察试样的微观形貌,在材料测试中起着重要的作用。扫描电镜主要由真空系统、电子光学系统、显示系统以及附属设备等组成。随着科技的不断发展,扫描电镜变得越来越普及,多数操作人员缺乏系统性的培训,操作水平参差不齐,对设备维护方面不够了解。以FEI Nova NanoSEM 450型场发射扫描电镜为例,介绍了该设备的一系列科学管理与规范操作方法,以期为相关操作人员提供参考。
文摘The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties,utilizing an impedance tube setup in accordance with ASTM standard E 1050-12.The Creality Ender-3,a 3D printer,was used for printing the honeycomb structures,and polylactic acid(PLA)material was employed for their construction.The organic,inorganic,and polymeric compounds within the composites were identified using fourier transformation infrared(FTIR)spectroscopy.The structure and homogeneity of the samples were examined using a field emission scanning electron microscope(FESEM).To determine the sound absorption coefficient of the 3D printed honeycomb structure,numerous samples were systematically developed using central composite design(CCD)and analysed using response surface methodology(RSM).The RSM mathematical model was established to predict the optimum values of each factor and noise reduction coefficient(NRC).The optimum values for an NRC of 0.377 were found to be 1.116 wt% carbon black,1.025 wt% aluminium powder,and 3.151 mm distance between parallel edges.Overall,the results demonstrate that a 3Dprinted honeycomb structure filled with nanofillers is an excellent material that can be utilized in various fields,including defence and aviation,where lightweight and acoustic properties are of great importance.
文摘Our research introduces a groundbreaking chemical reduction method for synthesizing silver nanoparticles, marking a significant advancement in the field. The nanoparticles were meticulously characterized using various techniques, including optical analysis, structural analysis, transmission electron microscopy (TEM), and field-emission scanning electron microscope (FESEM). This thorough process instills confidence in the accuracy of our findings. The results unveiled that the silver nanoparticles had a diameter of less than 20 nm, a finding of great importance. The absorption spectrum decreased in the peak wavelength range (405 - 394 mm) with increasing concentrations of Ag nanoparticles in the range (1 - 5%). The XRD results indicated a cubic crystal structure for silver nanoparticles with the lattice constant (a = 4.0855 Å), and Miller indices were (111), (002), (002), and (113). The simulation on the XRD pattern showed a face center cubic phase with space group Fm-3m, providing valuable insights into the structure of the nanoparticles.
基金financial support of the National Natural Science Foundation of China (Grant Nos.51979266,51879258 and 51991392)。
文摘Tamusu mudstone formation, located in the Alxa area in western Inner Mongolia, is considered a potential host formation for high-level radioactive waste(HLW) underground disposal in China. In this study, complementary analyses with X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), mercury intrusion porosimetry(MIP), and N_(2) physisorption isotherm were conducted on the Tamusu mudstone to characterize its physical characteristics and microstructural features, such as mineral compositions and pore structure. Several minerals, including carbonates, feldspar, clays and analcime, were identified in Tamusu mudstone by XRD. Images from FE-SEM show that pores in the Tamusu mudstone were dominantly on nanometer scale and generally located within their mineral matrix or at the interface with non-porous minerals. The combination of the MIP and N_2 physisorption curves indicated that the Tamusu mudstone has diverse pore sizes, a porosity varying from 2.34% to 2.84%, and a total pore volume in the range of 0.0065—0.0222 cm^(3)/g with the average pore diameter ranging from 9.6 nm to 19.23 nm. The specific surface area measured by MIP(2.572—5.861 m^(2)/g) was generally higher than that by N_(2) physisorption(1.29—3.04 m^(2)/g), due to the pore network effect, pore shape(e.g. ink-bottle shape), or technique limits. The results related to pore information can be applied as an input in the future to model single-or multi-phase fluid flow and the transport of radionuclides in porous geomedium by migration and diffusion.
文摘The analysis of gunshot residue(GSR) has played an integral role within the legal system in relation to shooting cases. With a characteristic elemental composition of lead, antimony, barium, and a typically discriminative spheroidal morphology, the presence and distribution of GSR can aid in firearm investigations. In this experiment, three shots of low velocity rim-fire ammunition were fired over polished silicon collection substrates placed at six intervals over a 100 cm range. The samples were analysed using a Field Emission Gun Scanning Electron Microscope(FEG-SEM) in conjunction with an X-flash Energy Dispersive X-ray(EDX) detector, allowing for GSR particle analyses of composition and structure at the sub-micron level. The results of this experiment indicate that although classic spheroidal particles are present consistently throughout the entire range of samples their sizes vary significantly, and at certain distances from the firearm particles with an irregular morphology were discerned, forming "impactdisrupted" GSR particles, henceforth colloquially referred to as "splats". Upon further analysis, trends with regards to the formation of these splat particles were distinguished. An increase in splat frequency was observed starting at 10 cm from the firearm, with 147 mm^(-2) splat density, reaching a maximal flux at 40 cm(451 mm^(-2)), followed by a gradual decrease to the maximum range sampled. Moreover, the structural morphology of the splats changes throughout the sampling range. At the distances closest to the firearm, molten-looking particles were formed, demonstrating the metallic residues were in a liquid state when their flight path was disrupted. However, at increased distances-primarily where the discharge plume was at maximum dispersion and moving away from the firearm, the residues have had time to cool in-fight resulting in semi-congealed and solid particles that subsequently disrupted upon impact, forming more structured as well as disaggregated splats. The relative compositions of the characteristic elements that are present in GSR also change in the different splat morphologies sampled,which may contribute to the particles' physical structures. Two distinct populations of splats were also observed: circular and elongated, which suggest the residues hit the substrate at different angles. The difference in the splat impact angle can be ascribed to the position of the residues within the firearm discharge plume; particles get caught up in the vortex that is created by the discharge gases behind the projectile as it leaves the barrel, thereby affecting their directionality and flight time. This reasoning could also justify the existence of both spheroidal and splat particles at certain distances. The novel sampling and analytical techniques used in this experiment have provided previously unknown information in relation to GSR structure and formation which could have greater implications to its current analysis amongst laboratories and law enforcement agencies worldwide.
