scholarly journals Intracellular bound chlorophyll residues identify 1 Gyr-old fossils as eukaryotic algae

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Marie Catherine Sforna ◽  
Corentin C. Loron ◽  
Catherine F. Demoulin ◽  
Camille François ◽  
Yohan Cornet ◽  
...  
Keyword(s):  
Metamorphic Rocks ◽  
Low Grade ◽  
Direct Identification ◽  
New Approach ◽  
X Ray ◽  
Eukaryotic Algae ◽  
Fundamental Step ◽  
In Situ Detection ◽  
Chlorophyll Derivatives

AbstractThe acquisition of photosynthesis is a fundamental step in the evolution of eukaryotes. However, few phototrophic organisms are unambiguously recognized in the Precambrian record. The in situ detection of metabolic byproducts in individual microfossils is the key for the direct identification of their metabolisms. Here, we report a new integrative methodology using synchrotron-based X-ray fluorescence and absorption. We evidence bound nickel-geoporphyrins moieties in low-grade metamorphic rocks, preserved in situ within cells of a ~1 Gyr-old multicellular eukaryote, Arctacellularia tetragonala. We identify these moieties as chlorophyll derivatives, indicating that A. tetragonala was a phototrophic eukaryote, one of the first unambiguous algae. This new approach, applicable to overmature rocks, creates a strong new proxy to understand the evolution of phototrophy and diversification of early ecosystems.

scholarly journals Non-dispersive UV Absorption Spectroscopy: A Promising New Approach for in-situ Detection of Sulfur Dioxide

2019 ◽  
Vol 7 ◽  
Author(s):  
Jan-Lukas Tirpitz ◽  
Denis Pöhler ◽  
Nicole Bobrowski ◽  
Bruce Christenson ◽  
Julian Rüdiger ◽  
...  
Keyword(s):  
Sulfur Dioxide ◽  
Absorption Spectroscopy ◽  
Uv Absorption ◽  
New Approach ◽  
Uv Absorption Spectroscopy ◽  
In Situ Detection

In situ back-side illumination fluorescence XAFS (BI-FXAFS) studies on platinum nanoparticles deposited on a HOPG surface as a model fuel cell: a new approach to the Pt-HOPG electrode/electrolyte interface

2014 ◽  
Vol 16 (27) ◽  
pp. 13748-13754 ◽  
Author(s):  
Hiromitsu Uehara ◽  
Yohei Uemura ◽  
Takafumi Ogawa ◽  
Kentaro Kono ◽  
Ryoichi Ueno ◽  
...  
Keyword(s):  
Fine Structure ◽  
Fuel Cell ◽  
Back Side ◽  
New Approach ◽  
X Ray ◽  
Model Fuel ◽  
Fluorescence Xafs ◽  
X Ray Absorption ◽  
Side Illumination

We measured the in situ polarization-dependent X-ray absorption fine structure of PtNPs deposited on a flat HOPG substrate.

Stratospheric CℓO: In-situ detection with a new approach

1985 ◽  
Vol 12 (7) ◽  
pp. 441-444 ◽  
Author(s):  
Wm. H. Brune ◽  
E. M. Weinstock ◽  
M. J. Schwab ◽  
R. M. Stimfle ◽  
J. G. Anderson
Keyword(s):  
New Approach ◽  
In Situ Detection

New approach in the monitoring and characterization of titanium nitride thin films

1999 ◽  
Vol 14 (2) ◽  
pp. 436-441 ◽  
Author(s):  
S. Logothetidis ◽  
E. I. Meletis ◽  
G. Kourouklis
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Ex Situ ◽  
New Approach ◽  
X Ray ◽  
Plasma Energy

In situ and ex situ spectroscopic ellipsometry (SE), Raman spectroscopy (RS), x-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) have been used to study the stoichiometry and characterize TiNx thin films deposited by magnetron sputtering at various stoichiometries. In situ SE can provide parameters, such as the plasma energy, that can be utilized for monitoring of the film stoichiometry. Besides plasma energy, optical phonon position in RS was also found to be a sensitive probe of TiNx stoichiometry as detected by RS, XPS, and ex situ SE. Under these conditions, AES faces difficulties for reliable film characterization, and the complementary use of other techniques is required for determining the exact film stoichiometry.

scholarly journals The soft X-ray Neupert effect as a proxy for solar energetic particle injection

2020 ◽  
Vol 10 ◽  
pp. 64
Author(s):  
Ruhann Steyn ◽  
Du Toit Strauss ◽  
Frederic Effenberger ◽  
Daniel Pacheco
Keyword(s):  
Thermal Emission ◽  
Transport Model ◽  
Solar Energetic Particle ◽  
Particle Injection ◽  
New Approach ◽  
X Ray ◽  
Neupert Effect ◽  
Long Duration ◽  
Cast Model

The acceleration and injection of solar energetic particles (SEPs) near the Sun is one of the major unsolved problems in contemporary SEP transport modeling efforts. Here, we establish a new approach to the injection problem by utilizing a correlation between the soft X-ray thermal emission in solar flares, and their hard X-ray counterpart, the so-called Neupert effect, which is indicative of the presence of non-thermal particles. We show that the resulting injection function, in the initial phase of the flare, is similar to those inferred from inverting the transport problem based on in-situ observations. For few cases, we find early injections with no in-situ correspondence, that can be caused by particles accelerated before there is a magnetic connection between the source and the spacecraft. The method has limitations for long-duration injections, since it is not applicable to the decay phase of the flare where particle trapping might play a role. For a sample of SEP events in 1980, observed with the Helios-1 and IMP8 spacecraft, we show the results of a 2D SEP transport model based on this approach. We discuss that, with this method, a physics-based, real-time operational SEP now-cast model for the heliosphere is feasible.

Characterization of a low-grade copper-sulphide ore to assess its suitability for in situ recovery

2017 ◽  
Vol 32 (S2) ◽  
pp. S78-S84
Author(s):  
Jian Li ◽  
Laura Kuhar ◽  
Peter Austin ◽  
Micheal Da Costa
Keyword(s):  
New Technologies ◽  
Copper Recovery ◽  
Low Grade ◽  
Mineralogical Characterization ◽  
X Ray ◽  
Sulphide Ore ◽  
Computed Tomography Scanning ◽  
Valuable Metals ◽  
Copper Gold

CSIRO Minerals is developing new technologies and approaches for the in situ recovery (ISR) of valuable metals. ISR provides opportunities to process small and/or deep deposits and could create additional revenue for conventional uneconomic mines. Unlike for conventional processing, no standard methodology exists for characterizing sample suitability for ISR. The authors are developing a workflow to understand sample and deposit amenability to ISR processing. A South Australian low-grade iron-oxide-copper-gold sulphide ore was studied. A total of 37 drill cores samples were obtained from the ore sample for detailed mineralogical and leaching characterization. A range of characterization techniques including chemical analysis, X-ray fluorescence mapping, quantitative evaluation of minerals by scanning electron microscopy, computed tomography scanning, and bulk- and micro-X-ray diffraction analyses were applied to understand the ore mineralogy. Leaching tests at 50 °C were performed on selected samples to understanding their leaching behaviour. Mineralogical characterization found that copper was present mostly as discrete secondary copper sulphides distributed in various areas and at various specimen depths, which, in theory should be readily available for leaching, provided sufficient solution access exists. Leaching results showed steady copper recovery under the conditions tested. This study provides insight into understanding the suitability of an ore for ISR processing.

Demonstration of an X-ray Fluorescence Sensor for the Cone Penetrometer

1995 ◽  
Vol 39 ◽  
pp. 861-867 ◽  
Author(s):  
W. T. Elam ◽  
J. V. Gilfrich
Keyword(s):  
Heavy Metal ◽  
High Voltage ◽  
Research Laboratory ◽  
Detection Limits ◽  
Naval Research ◽  
Cone Penetrometer ◽  
X Ray ◽  
Feasibility Test ◽  
In Situ Detection

A feasibility test at the Naval Research Laboratory has shown that a miniature X-ray Fluorescence (XRF) sensor can be constructed for the cone penetrometer. Such a sensor would have detection limits for heavy metal contaminants in soils of a few parts per million. The next step is to demonstrate the capabilities of such a sensor in the cone penetrometer. A sensor for this purpose is being constructed and will be tested both in the laboratory and in the field. The XRF sensor will be capable of evaluating the in-situ detection limits and field screening (semi-quantitative) capabilities of x-ray fluorescence and can be transitioned to field activities for further evaluation and feedback. The sensor will consist of a miniature x-ray tube and an x-ray detector, together with appropriate apertures and x-ray filters, in a custom fabricated section of penetrometer pipe. The sensor will use commercially available components. High voltage and signal cables will couple the sensor to electronics in the truck. Boron carbide will be used for the x-ray windows which protect the sensor components from soil abrasion.

Mineralogy and genesis of the Pugu Hill kaolin deposit, Tanzania

Clay Minerals ◽  
1987 ◽  
Vol 22 (4) ◽  
pp. 401-409 ◽  
Author(s):  
B. Schwaighofer ◽  
H. W. Müller
Keyword(s):  
River System ◽  
Field Studies ◽  
Metamorphic Rocks ◽  
Decomposition Products ◽  
X Ray ◽  
Uluguru Mountains ◽  
Channel Deposits ◽  
Kaolin Deposit ◽  
Arkosic Sandstone

AbstractAccording to field studies of the Pugu Hill kaolin deposit and mineralogical investigations (X-ray, SEM), two main types of Miocene sandstones are distinguished: (i) clayey-silty kaolinitic sandstones with stacks of idiomorphic pseudohexagonal kaolinite crystals; (ii) massive clayey-silty kaolinitic sandstones with irregular fabric of isolated kaolinite plates. The Precambrian metamorphic rocks of the Uluguru Mountains are a probable source for the kaolinitic sediments of the Pugu Hill Formation. Decomposition products of weathering profiles on meta-anorthosites are mainly 7Å- and 10Å-halloysite and gibbsite. It is suggested that the kaolinitic sandstones were deposited in a former delta. The first sandstone type is considered to have developed in situ from weathered arkosic sandstone, and the second represents channel deposits in an old river system (probably a Miocene predecessor of the Ruvu River) with kaolin transported from a hinterland and redeposited. The variable formation and fabric of the kaolinites in the Pugu Hill Formation are due to in situ weathering of transported primary minerals (fedspar), and to transported weathered material (with secondary halloysite).

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