To explore ways to improve the accuracy of quantitative analysis of samples in the micrometer to nanometer range of magnitudes,we adopted analytical transmission electron microscopy(AEM/EDS)for qualitative and quantit...To explore ways to improve the accuracy of quantitative analysis of samples in the micrometer to nanometer range of magnitudes,we adopted analytical transmission electron microscopy(AEM/EDS)for qualitative and quantitative analysis of pyrite materials.Additionally,the k factor of pyrite is calculated experimentally.To develop an appropriate non-standard quantitative analysis model for pyrite materials,the experimentally calculated k factor is compared with that estimated from the non-standard quantitative analytical model of the instrument software.The experimental findings demonstrate that the EDS attached to a TEM can be employed for precise quantitative analysis of micro-and nanoscale regions of pyrite materials.Furthermore,it serves as a reference for improving the results of the EDS quantitative analysis of other sulfides.展开更多
This study determines the geochemical and depositional environment analysis of the sediments of the Sohnari Member of the Laki Formation, Northern Kirthar Fold Belt of Pakistan. The Energy-Dispersive-X-Ray Spectroscop...This study determines the geochemical and depositional environment analysis of the sediments of the Sohnari Member of the Laki Formation, Northern Kirthar Fold Belt of Pakistan. The Energy-Dispersive-X-Ray Spectroscopy (EDS) technique is used for the detection of major elements and the effects of shifting depositional climatic conditions of six representative samples which were acquired from the Sohnari Member of the Laki Formation at Lakhra area, Sindh, Pakistan. The sedimentological studies clarify that the sediments the Sonahri Member are relatively immature and most migrated in clastic mode. The availability of Silica shows that the Member was formed due to biochemical precipitation and detrital mode and was deposited at a fast rate of sediment deposition under the fluvio-deltaic depositional system. This is also deduced that the rapid rate of sediment deposition might be created a reducing atmosphere and allowing for the mineralization of sulphur.展开更多
The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the...The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the magnetic minerals present in ordinary and carbonaceous chondrites, providing information on the evolution of magnetic fields. The interaction of organic compounds with magnetic minerals is a possible source of chemical diversity, which is crucial for molecular evolution. Carbon compounds in meteorites are of great scientific interest for a variety of reasons, such as their relevance to the origins of chirality in living organisms. This study presents the characterization of organic and mineral compounds in the Allende meteorite. The structural and physicochemical characterization of the Allende meteorite was accomplished through light microscopy, powder X-ray diffraction with complementary Rietveld refinement, Raman and infrared spectroscopy, mass spectrometry, scanning electron microscopy, and atomic force microscopy using magnetic signal methods to determine the complex structure and the interaction of organic compounds with magnetic Ni-Fe minerals. The presence of Liesegang-like patterns of chondrules in fragments of the Allende structure may also be relevant to understanding how the meteorite was formed. Other observations include the presence of magnetic materials and nanorod-like solids with relatively similar sizes as well as the heterogeneous distribution of carbon in chondrules. Signals observed in the Raman and infrared spectra resemble organic compounds such as carbon nanotubes and peptide-like molecules that have been previously reported in other meteorites, making the Mexican Allende meteorite a feasible sample for the study of the early Earth and exoplanetary bodies.展开更多
This paper reviews research on coprolites from India,providing the first evidence of microcoprolites from the early Miocene(Aquitanian)Khari Nadi Formation sedimentary succession,exposed about 1.5 km northeast of the ...This paper reviews research on coprolites from India,providing the first evidence of microcoprolites from the early Miocene(Aquitanian)Khari Nadi Formation sedimentary succession,exposed about 1.5 km northeast of the village of Kotada,Kachchh(Kutch)District,Gujarat State,western India.Morphometric and size comparisons(in a statistical framework)with known coprolites from the Mesozoic-Cenozoic successions of India(including those recorded herein)and globally suggest that fishes were the likely producers of the Kotada coprolites.Scanning electron microscopy confirms the presence of fish dental remains within the coprolites,while both Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray Spectroscopy(EDS)reveal the phosphatic nature of the microscopic coprolite specimens(recorded herein)hinting that the producer(s)were predominantly carnivorous(ichthyophagous)in their diet.Furthermore,X-Ray Fluorescence(XRF)analysis of the host and associated lithologies allows us to deduce that the Kotada coprolites were deposited in a shallow marine environment,with possible aerial exposure of the host lithology occurring at some point after deposition.To the best of our knowledge,the present report is the first record of microscopic fish coprolites from India,as well as being the first from the Aquitanian of India and the oldest Neogene record from India.展开更多
Natural magnetic black sands are known from several sites often located in areas of volcanic origin. Their elemental and mineral composition provides information on the geology of their territory and depends on severa...Natural magnetic black sands are known from several sites often located in areas of volcanic origin. Their elemental and mineral composition provides information on the geology of their territory and depends on several factors occurred during their formation. A sample of black sand was collected on the seashore of the island of Mayotte in the Indian Ocean and its magnetic part was investigated by means of energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), and MÖssbauer spectroscopy at room temperature. The mineral composition is dominantly magnetite, in good agreement with samples collected in other sites of volcanic origin. Contrary to pure magnetite, a relevant fraction of Ti was detected by EDS. The 16% Ti and 1% Mn content increase the magnetite lattice parameter to 8.4312 (25) Å. The broadening of XRD lines pointed towards a significant degree of disorder. This was confirmed by MÖssbauer spectroscopy and is attributed to the presence of Ti replacing Fe in the magnetite lattice. The presence of Ti modifies the local magnetic field on the Fe sites, leading to a broader and more complex MÖssbauer transmission spectrum with respect to the one of pure magnetite. To study the effect of temperature, samples were heated for 12 hours to 600°C and 800°C in argon and to 1000°C in air. Annealing in argon did not improve the crystallinity while annealing in air caused a complete decomposition of magnetite into hematite and pseudobrookite.展开更多
The study of natural magnetic sands is instrumental to investigate the geological aspects of their formation and of the origin of their territory. In particular, Mossbauer spectroscopy provides unique information on t...The study of natural magnetic sands is instrumental to investigate the geological aspects of their formation and of the origin of their territory. In particular, Mossbauer spectroscopy provides unique information on their iron content and on the oxidation state of iron in their mineral composition. The Italian coast on the Mediterranean Sea near Rome is known for the presence of highly magnetic black sands of volcanic origin. A study of the room temperature Mossbauer spectrum, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and magnetic measurements of a sample of black magnetic sand collected on the seashore of the town of Ladispoli is performed. This study reveals magnetite as main constituent with iron in both tetrahedral and octahedral sites. Minor constituents are the iron minerals hematite and ilmenite, the iron containing minerals diopsite, gossular, and allanite, as well as ubiquitous sanidine, quartz, and calcite.展开更多
Elastomeric materials show promise as potential micro-fillers in brake linings.They can provide vibration damping and acoustic advantages in intermittent and abrupt impact applications such as braking.The elastomeric ...Elastomeric materials show promise as potential micro-fillers in brake linings.They can provide vibration damping and acoustic advantages in intermittent and abrupt impact applications such as braking.The elastomeric material can be salvaged from non-biodegradable automotive tires,thereby providing an opportunity to reuse materials that will otherwise be discarded in landfills.Both tribological and thermomechanical performances of the waste tire rubber were assessed to determine their potential for use as micro-fillers in the brake linings of commercial vehicles with a gross weight less than 16 tons.Accordingly,the brake lining materials were fabricated with fine waste tire rubber particulates(WTRPs)as the micro-fillers,phenolic-R resin as the binder,graphite as the dry lubricant,laterite as the co-filler,and coconut coir for natural fiber reinforcement.The effects of increasing the WTRP weight fraction on the brake response of the linings were analyzed,and the different compositions were benchmarked against a commercial brake lining.Mechanical characterization comprising compressive strength,hardness,density,and porosity studies were carried out.Frictional and wear characteristics of the linings were analyzed using a rotary tribometer with simultaneous thermal monitoring.The manufactured lining with 15 wt%WTRPs exhibited a mean friction coefficient of^0.38,a specific volumetric loss rate of 1,662μm3/(N?m),and improved thermal response.Using optical microscopy and scanning electron microscopy(SEM)with energy dispersive spectroscopy(EDS),wear surface morphology studies compared the relative development of primary and secondary plateaus and revealed the redistribution of wear debris,leading to the stability of the coefficient of friction.展开更多
Clean energy innovation has triggered the development of single-atom catalysts(SACs)due to their excellent catalytic activity,high tunability and low cost.The success of SACs for many catalytic reactions has opened a ...Clean energy innovation has triggered the development of single-atom catalysts(SACs)due to their excellent catalytic activity,high tunability and low cost.The success of SACs for many catalytic reactions has opened a new field,where the fundamentals of catalytic property-structure relationship at atomic level await exploration,and thus raises challenges for structural characterization.Among the characterization techniques for SACs,aberration-corrected transmission electron microscopy(TEM)has become an essential tool for direct visualization of single atoms.In this review,we briefly summarize recent studies on SACs using advanced TEM.We first introduce TEM methods,which are particularly important for SACs characterization,and then discuss the applications of advanced TEM for SAC characterization,where not only atomic dispersion of single atoms can be studied,but also the distribution of elements and the valence state with local coordination can be resolved.We further extend our review towards in-situ TEM,which has increasing importance for the fundamental understanding of catalytic mechanism.Perspectives of TEM for SACs are finally discussed.展开更多
基金Funded by the International Science&Technology Cooperation Program of Hubei Province of China(No.2022EHB024)。
文摘To explore ways to improve the accuracy of quantitative analysis of samples in the micrometer to nanometer range of magnitudes,we adopted analytical transmission electron microscopy(AEM/EDS)for qualitative and quantitative analysis of pyrite materials.Additionally,the k factor of pyrite is calculated experimentally.To develop an appropriate non-standard quantitative analysis model for pyrite materials,the experimentally calculated k factor is compared with that estimated from the non-standard quantitative analytical model of the instrument software.The experimental findings demonstrate that the EDS attached to a TEM can be employed for precise quantitative analysis of micro-and nanoscale regions of pyrite materials.Furthermore,it serves as a reference for improving the results of the EDS quantitative analysis of other sulfides.
文摘This study determines the geochemical and depositional environment analysis of the sediments of the Sohnari Member of the Laki Formation, Northern Kirthar Fold Belt of Pakistan. The Energy-Dispersive-X-Ray Spectroscopy (EDS) technique is used for the detection of major elements and the effects of shifting depositional climatic conditions of six representative samples which were acquired from the Sohnari Member of the Laki Formation at Lakhra area, Sindh, Pakistan. The sedimentological studies clarify that the sediments the Sonahri Member are relatively immature and most migrated in clastic mode. The availability of Silica shows that the Member was formed due to biochemical precipitation and detrital mode and was deposited at a fast rate of sediment deposition under the fluvio-deltaic depositional system. This is also deduced that the rapid rate of sediment deposition might be created a reducing atmosphere and allowing for the mineralization of sulphur.
文摘The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the magnetic minerals present in ordinary and carbonaceous chondrites, providing information on the evolution of magnetic fields. The interaction of organic compounds with magnetic minerals is a possible source of chemical diversity, which is crucial for molecular evolution. Carbon compounds in meteorites are of great scientific interest for a variety of reasons, such as their relevance to the origins of chirality in living organisms. This study presents the characterization of organic and mineral compounds in the Allende meteorite. The structural and physicochemical characterization of the Allende meteorite was accomplished through light microscopy, powder X-ray diffraction with complementary Rietveld refinement, Raman and infrared spectroscopy, mass spectrometry, scanning electron microscopy, and atomic force microscopy using magnetic signal methods to determine the complex structure and the interaction of organic compounds with magnetic Ni-Fe minerals. The presence of Liesegang-like patterns of chondrules in fragments of the Allende structure may also be relevant to understanding how the meteorite was formed. Other observations include the presence of magnetic materials and nanorod-like solids with relatively similar sizes as well as the heterogeneous distribution of carbon in chondrules. Signals observed in the Raman and infrared spectra resemble organic compounds such as carbon nanotubes and peptide-like molecules that have been previously reported in other meteorites, making the Mexican Allende meteorite a feasible sample for the study of the early Earth and exoplanetary bodies.
基金funding support from BSIP in the form of In-house Project No.2.17(XIII five-year plan)。
文摘This paper reviews research on coprolites from India,providing the first evidence of microcoprolites from the early Miocene(Aquitanian)Khari Nadi Formation sedimentary succession,exposed about 1.5 km northeast of the village of Kotada,Kachchh(Kutch)District,Gujarat State,western India.Morphometric and size comparisons(in a statistical framework)with known coprolites from the Mesozoic-Cenozoic successions of India(including those recorded herein)and globally suggest that fishes were the likely producers of the Kotada coprolites.Scanning electron microscopy confirms the presence of fish dental remains within the coprolites,while both Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray Spectroscopy(EDS)reveal the phosphatic nature of the microscopic coprolite specimens(recorded herein)hinting that the producer(s)were predominantly carnivorous(ichthyophagous)in their diet.Furthermore,X-Ray Fluorescence(XRF)analysis of the host and associated lithologies allows us to deduce that the Kotada coprolites were deposited in a shallow marine environment,with possible aerial exposure of the host lithology occurring at some point after deposition.To the best of our knowledge,the present report is the first record of microscopic fish coprolites from India,as well as being the first from the Aquitanian of India and the oldest Neogene record from India.
文摘Natural magnetic black sands are known from several sites often located in areas of volcanic origin. Their elemental and mineral composition provides information on the geology of their territory and depends on several factors occurred during their formation. A sample of black sand was collected on the seashore of the island of Mayotte in the Indian Ocean and its magnetic part was investigated by means of energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), and MÖssbauer spectroscopy at room temperature. The mineral composition is dominantly magnetite, in good agreement with samples collected in other sites of volcanic origin. Contrary to pure magnetite, a relevant fraction of Ti was detected by EDS. The 16% Ti and 1% Mn content increase the magnetite lattice parameter to 8.4312 (25) Å. The broadening of XRD lines pointed towards a significant degree of disorder. This was confirmed by MÖssbauer spectroscopy and is attributed to the presence of Ti replacing Fe in the magnetite lattice. The presence of Ti modifies the local magnetic field on the Fe sites, leading to a broader and more complex MÖssbauer transmission spectrum with respect to the one of pure magnetite. To study the effect of temperature, samples were heated for 12 hours to 600°C and 800°C in argon and to 1000°C in air. Annealing in argon did not improve the crystallinity while annealing in air caused a complete decomposition of magnetite into hematite and pseudobrookite.
文摘The study of natural magnetic sands is instrumental to investigate the geological aspects of their formation and of the origin of their territory. In particular, Mossbauer spectroscopy provides unique information on their iron content and on the oxidation state of iron in their mineral composition. The Italian coast on the Mediterranean Sea near Rome is known for the presence of highly magnetic black sands of volcanic origin. A study of the room temperature Mossbauer spectrum, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and magnetic measurements of a sample of black magnetic sand collected on the seashore of the town of Ladispoli is performed. This study reveals magnetite as main constituent with iron in both tetrahedral and octahedral sites. Minor constituents are the iron minerals hematite and ilmenite, the iron containing minerals diopsite, gossular, and allanite, as well as ubiquitous sanidine, quartz, and calcite.
文摘Elastomeric materials show promise as potential micro-fillers in brake linings.They can provide vibration damping and acoustic advantages in intermittent and abrupt impact applications such as braking.The elastomeric material can be salvaged from non-biodegradable automotive tires,thereby providing an opportunity to reuse materials that will otherwise be discarded in landfills.Both tribological and thermomechanical performances of the waste tire rubber were assessed to determine their potential for use as micro-fillers in the brake linings of commercial vehicles with a gross weight less than 16 tons.Accordingly,the brake lining materials were fabricated with fine waste tire rubber particulates(WTRPs)as the micro-fillers,phenolic-R resin as the binder,graphite as the dry lubricant,laterite as the co-filler,and coconut coir for natural fiber reinforcement.The effects of increasing the WTRP weight fraction on the brake response of the linings were analyzed,and the different compositions were benchmarked against a commercial brake lining.Mechanical characterization comprising compressive strength,hardness,density,and porosity studies were carried out.Frictional and wear characteristics of the linings were analyzed using a rotary tribometer with simultaneous thermal monitoring.The manufactured lining with 15 wt%WTRPs exhibited a mean friction coefficient of^0.38,a specific volumetric loss rate of 1,662μm3/(N?m),and improved thermal response.Using optical microscopy and scanning electron microscopy(SEM)with energy dispersive spectroscopy(EDS),wear surface morphology studies compared the relative development of primary and secondary plateaus and revealed the redistribution of wear debris,leading to the stability of the coefficient of friction.
基金National Natural Science Foundation of China(No.12074017)Beijing Municipal High Level Innovative Team Building Program,China(No.IDHT20190503)National Natural Science Fund for Innovative Research Groups of China(No.51621003).
文摘Clean energy innovation has triggered the development of single-atom catalysts(SACs)due to their excellent catalytic activity,high tunability and low cost.The success of SACs for many catalytic reactions has opened a new field,where the fundamentals of catalytic property-structure relationship at atomic level await exploration,and thus raises challenges for structural characterization.Among the characterization techniques for SACs,aberration-corrected transmission electron microscopy(TEM)has become an essential tool for direct visualization of single atoms.In this review,we briefly summarize recent studies on SACs using advanced TEM.We first introduce TEM methods,which are particularly important for SACs characterization,and then discuss the applications of advanced TEM for SAC characterization,where not only atomic dispersion of single atoms can be studied,but also the distribution of elements and the valence state with local coordination can be resolved.We further extend our review towards in-situ TEM,which has increasing importance for the fundamental understanding of catalytic mechanism.Perspectives of TEM for SACs are finally discussed.
