scholarly journals New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

2015 ◽  
Vol 12 (3) ◽  
pp. 863-873 ◽  
Author(s):  
A. Alexandre ◽  
I. Basile-Doelsch ◽  
T. Delhaye ◽  
D. Borshneck ◽  
J. C. Mazur ◽  
...  
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Extraction Procedure ◽  
Chemical Extraction ◽  
Natural Environments ◽  
X Ray ◽  
C Cycle ◽  
Internal Cavities ◽  
The Subject ◽  
Occluded Carbon

Abstract. Phytoliths contain occluded organic compounds called phytC. Recently, phytC content, nature, origin, paleoenvironmental meaning and impact in the global C cycle have been the subject of increasing debate. Inconsistencies were fed by the scarcity of in situ characterizations of phytC in phytoliths. Here we reconstructed at high spatial resolution the 3-D structure of harvested grass short cell (GSC) phytoliths using 3-D X-ray microscopy. While this technique has been widely used for 3-D reconstruction of biological systems it has never been applied in high-resolution mode to silica particles. Simultaneously, we investigated the location of phytC using nanoscale secondary ion mass spectrometry (NanoSIMS). Our data evidenced that the silica structure contains micrometric internal cavities. These internal cavities were sometimes observed isolated from the outside. Their opening may be an original feature or may result from a beginning of dissolution of silica during the chemical extraction procedure, mimicking the progressive dissolution process that can happen in natural environments. The phytC that may originally occupy the cavities is thus susceptible to rapid oxidation. It was not detected by the NanoSIMS technique. However, another pool of phytC, continuously distributed in and protected by the silica structure, was observed. Its N/C ratio (0.27) is in agreement with the presence of amino acids. These findings constitute a basis to further characterize the origin, occlusion process, nature and accessibility of phytC, as a prerequisite for assessing its significance in the global C cycle.

scholarly journals New highlights on phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

2014 ◽  
Vol 11 (10) ◽  
pp. 14699-14727 ◽  
Author(s):  
A. Alexandre ◽  
I. Basile-Doelsch ◽  
T. Delhaye ◽  
D. Borshneck ◽  
J. C. Mazur ◽  
...  
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Extraction Procedure ◽  
Chemical Extraction ◽  
Natural Environments ◽  
X Ray ◽  
3 Dimensional ◽  
C Cycle ◽  
Internal Cavities

Abstract. Phytoliths contain occluded organic compounds called phytC. Recently, phytC content, nature, origin, paleoenvironmental meaning and impact in the global C cycle has been the subject of increasing debate. Inconsistencies were fed by the scarcity of in-situ characterization of phytC in phytoliths. Here we reconstructed at high spatial resolution the 3-dimensional (3-D) structure of harvested grass short cell (GSC) phytoliths using 3-D X-ray microscopy. While this technic has been widely used for 3-D reconstruction of biological systems it has never been applied in high resolution mode to silica particles. Simultaneously, we investigated the location of phytC using Nano-scale Secondary Ion Mass Spectrometry (NanoSIMS). Our data evidenced that the silica structure contains micrometric internal cavities. These internal cavities were sometimes observed isolated from the outside. Their opening may be an original feature or may result from a beginning of dissolution of silica during the chemical extraction procedure, mimicking the progressive dissolution process that can happen in natural environments. The phytC that may originally occupy the cavities is thus susceptible to rapid oxidation. It was not detected by the nanoSIMS technique. To the contrary another pool of phytC, continuously distributed in and protected by the silica structure was evidenced. Its N/C ratio (0.27) is in agreement with the presence of amino acids. These findings allowed to discuss discrepancies in phytC quantification, evaluate phytC accessibility to oxidation, and reassess the paleo-environmental meaning of opaque features observed in phytoliths by natural light (NL) microcopy. They also should help to reappraise the significance of phytC in the global C cycle.

Research of plastic ice, mineral formations and air of multi-frozen karst cave Heetey in Transbaikalia

2020 ◽  
Vol 26 (7) ◽  
pp. 33-43
Author(s):  
I. Zheleznyak ◽  
◽  
S. Tsyrenzhapov ◽  
А. Gurulev ◽  
◽  
...  
Keyword(s):  
Radon Concentration ◽  
Maximum Level ◽  
Natural Environments ◽  
Geochemical Background ◽  
Karst Cave ◽  
Ice Volume ◽  
Internal Cavities ◽  
The Subject ◽  
Microwave Radiometers ◽  
Physical And Chemical

Heetey caves (“cold” and “warm”) which are located in the southern part of the permafrost in the Transbaikal Region have been chosen as the object of the research in the article. The subject is the physical and chemical parameters of the object. The results of the research in the “cold” Heetey cave are given in more detail. The following methods of this object research were chosen: study of the chemical composition of cave air using a chromatograph; radar survey of the cave grotto in the centimeter range; measurement of its own radio-thermal radiation using microwave radiometers. As a result of the research, the following results were obtained. The article provides information on the natural conditions that determine the dependence of the state of natural environments in the Heetey karst caves. The characteristics of occurrence and composition conditions of the natural environments of a karst cave (geological, cryogenic, atmospheric, groundwater) are given, taking into account the cryogenesis of their formation, transformation and influence on the cave air composition. A description of a rare low-temperature mineral, aragonite, which was first discovered in the cave and which is transformed into calcite over time is described. It is shown that the ice cover at the bottom of the cave has a layered structure, which is due to the seasonal ingress of surface water into the cave. The results of measurements of the surface air composition above the rocks’ surface and in caves, namely the content of oxygen, nitrogen, carbon dioxide, explosive gases – methane and hydrogen, mercury vapors are presented. A previously unknown fact of an increased geochemical background of radon concentration has been established. The most probable reasons for the formation and increased background of radon concentration are indicated. Microwave radiometric measurements have shown that there has been warming inside the cave over the past decade. This fact is associated with a general warming of the climate in Transbaikalia, as well as with an increase in the number of visits to caves by unorganized tourists. With the use of a 10 GHz nanosecond radar, hidden internal cavities were discovered in the roof of the cave, which can further lead to its destruction. The prints on the walls of the cave (in its lower part) show that the level of the ice sheet in 2015 is lower than its maximum level (1990) by 10 cm, which corresponds to a loss of ice volume of 12...15 m3 per year

Micromechanisms of Deformation and Fracture in Rapidly Solidified Ni3Al Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
G. Liu ◽  
G.M. Bond
Keyword(s):  
Dislocation Motion ◽  
In Situ Tem ◽  
Intermetallic Alloys ◽  
Stress Concentrations ◽  
X Ray ◽  
Deformation And Fracture ◽  
The Subject ◽  
Rapidly Solidified ◽  
Degree Of Order

ABSTRACTRapidly solidified Ni76 Al24 ribbons, with and without boron, have been the subject of in-situ TEM deformation studies, as well as X-ray and TEM characterization and TEM fractography. The aim has been to gain a better understanding of the influence of a reduced degree of order on grainboundary behavior and ductility. This, in turn, allows fresh insights to be gained, both into the manner in which boron additions can enhance ductility, and into the potential usefulness of sequential ordering in intermetallic alloys with a tendency to intergranular failure. Lower degrees of order are found to reduce stress concentrations at grain boundaries; this effect is due to easier generation of dislocations from boundary sources, and, to a lesser extent, the braking action of thermal APB's on dislocation motion. The beneficial effect of boron on ductility is seen to result, at least in part, from enhanced boundary cohesive strength.

scholarly journals In Situ Recrystallization of Co-Evaporated Cu(In,Ga)Se2 Thin Films by Copper Chloride Vapor Treatment towards Solar Cell Applications

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3938
Author(s):  
Deewakar Poudel ◽  
Benjamin Belfore ◽  
Tasnuva Ashrafee ◽  
Elizabeth Palmiotti ◽  
Shankar Karki ◽  
...  
Keyword(s):  
Thin Films ◽  
Secondary Ion Mass Spectrometry ◽  
Copper Chloride ◽  
Recrystallization Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stage Process ◽  
Secondary Ion ◽  
Vapor Treatment

Cu(In,Ga)Se2 (or CIGS) thin films and devices were fabricated using a modified three-stage process. Using high deposition rates and a low temperature during the process, a copper chloride vapor treatment was introduced in between the second and third stages to enhance the films properties. X-ray diffraction and scanning electron microscopy demonstrate that drastic changes occur after this recrystallization process, yielding films with much larger grains. Secondary ion mass spectrometry shows that the depth profile of many elements is not modified (such as Cu, In and Se) while others change dramatically (such as Ga and Na). Because of the competing effects of these changes, not all parameters of the solar cells are enhanced, yielding an increase of 15% in the device efficiency at the most.

scholarly journals <i>In situ</i> interactive characteristics of reactive minerals in soil colloids and soil carbon preservation differentially revealed by nanoscale secondary ion mass spectrometry and X-ray absorption fine structure spectroscopy

2016 ◽  
Author(s):  
Jian Xiao ◽  
Xinhua He ◽  
Ying Zhou ◽  
Lirong Zheng ◽  
Jialong Hao ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Fine Structure ◽  
Secondary Ion Mass Spectrometry ◽  
Organic Fertilization ◽  
X Ray ◽  
Submicron Scale ◽  
X Ray Absorption ◽  
Secondary Ion ◽  
Soil Colloids

Abstract. Mineral binding is a major mechanism for soil carbon (C) stabilization. However, the submicron information about the in situ mechanisms of different fertilization practices affecting organo-mineral complexes and associated C preservation remains unclear. Here, we applied nano-scale 20 secondary ion mass spectrometry (NanoSIMS), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure spectroscopy (XAFS) to examine differentiating effects of inorganic versus organic fertilization on interactions between highly reactive minerals and soil C preservation. To examine such interactions, soils and their extracted colloids were collected during a 24-year long-term fertilization period (1990-2014) (no-fertilization, Control; chemical nitrogen (N), phosphorus (P) and 25 potassium (K) fertilization, NPK; and NPK plus swine manure fertilization, NPKM). The results for different fertilization conditions showed a ranked soil organic matter (SOM) concentration with NPKM > NPK > Control. Meanwhile, oxalate extracted Al (Alo), Fe (Feo), short range ordered (SRO) Al (Alxps), Fe (Fexps), and dissolved organic carbon (DOC) ranked with NPKM > Control > NPK, but ratios of DOC/Alxps and DOC/Fexps ranked with NPKM > NPK > Control. Compared with the NPK 30 treatment, NPKM treatment enhanced the C binding loadings of Al and Fe minerals in soil colloids at the submicron scale. Furthermore, a greater concentration of highly reactive Al and Fe minerals was present under NPKM than under NPK. Together, these submicron scale findings suggest that both reactive mineral species and their associations with C are differentially affected by inorganic and organic fertilization.

A Practical Approach to Low Temperature Microscopy and X-Ray Microanalysis

2000 ◽  
Vol 6 (S2) ◽  
pp. 306-307
Author(s):  
Patrick Echlin
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Building Block ◽  
Solid Matrix ◽  
X Ray ◽  
State Water ◽  
The Subject ◽  
Living Material ◽  
Low Temperature Microscopy

Water is the most abundant and most important molecule in the hydrosphere, outer lithosphere and the biosphere of our planet. It is also the most abundant and energetically the least expensive building block of living material, forms an integral parts of natural inorganic matrices such as soil and is a constituent of many synthetic organic materials such as paints and polymers. Paradoxically, water does not exist naturally, in the pure state. Water, when converted to the solid state, can provide the perfect matrix in which we may observe the structure and study the in situ chemistry of hydrated samples. We will consider the nature of this solid matrix, and its constituent components in a range of sample, and show how it may be formed, manipulated, examined and analysed. In the short amount of time and space available, one can do little more than highlight the main features of the subject.

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