scholarly journals Deciphering Silicification Pathways of Fossil Forests: Case Studies from the Late Paleozoic of Central Europe

Minerals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 432 ◽  
Author(s):  
Steffen Trümper ◽  
Ronny Rößler ◽  
Jens Götze
Keyword(s):  
Central Europe ◽  
Lattice Defect ◽  
Late Paleozoic ◽  
Polarizing Microscopy ◽  
Hydrothermal Quartz ◽  
Complex Processes ◽  
Physico Chemical ◽  
Oxygen Hole ◽  
Intensity Ratios ◽  
Chemical Conditions

The occurrence and formation of silicified wood from five late Paleozoic basins in Central Europe was investigated. Fossil wood from diverse geological settings was studied using field observations, taphonomic determinations as well as mineralogical analyses (polarizing microscopy, cathodoluminescence (CL) microscopy and spectroscopy). The results indicate that silicification is either a monophase or multiphase process under varying physico-chemical conditions. In particular, CL studies revealed complex processes of silica accumulation and crystallization. The CL characteristics of quartz phases in silicified wood can mostly be related to blue (390 and 440 nm), yellow (580 nm), and red (650 nm) emission bands, which may appear in different combinations and varying intensity ratios. Yellow CL is typical for initial silicification, reflecting quick precipitation under oxygen-deficient conditions caused by initial decay of the organic material. Blue CL is predominantly of secondary origin, resulting from replacement of precursor phases by a secondary hydrothermal quartz generation or subsequent silicification of wood. The red CL can be related to a lattice defect (non-bridging oxygen hole center—NBOHC).

Viability of nematode eggs in high rate algal ponds: the effect of physico-chemical conditions

2000 ◽  
Vol 42 (10-11) ◽  
pp. 371-374 ◽  
Author(s):  
S. Araki ◽  
J. M. González ◽  
E. de Luis ◽  
E. Bécares
Keyword(s):  
Hydraulic Retention Time ◽  
Pilot Scale ◽  
High Rate ◽  
Sterile Water ◽  
Egg Viability ◽  
High Rate Algal Ponds ◽  
Helminth Eggs ◽  
Physico Chemical ◽  
Nematode Eggs ◽  
Chemical Conditions

The viability of Parascaris equorum eggs was studied in two experimental pilot-scale high-rate algal ponds (HRAPs) working in parallel with 4 and 10 days hydraulic retention time respectively. Semi-permeable bags of cellulose (15000 daltons pore size) were used to study the effect of physico-chemical conditions on the survival of these helminth eggs. Three thousand eggs were used in each bag. Replicates of these bags were submerged for 4 and 10 days in the HRAPs and egg viability was compared with that in control bags submerged in sterile water. After 4 days exposure, 60% reduction in viability was achieved, reaching 90% after 10 days, much higher than the 16% and 25% found in the control bags for 4 and 10 days respectively. Ionic conditions of the HRAP may have been responsible for up to 50–60% of the egg mortality, suggesting that mortality due to the ionic environment could be more important than physical retention and other potential removal factors.

scholarly journals Compartmentalization of bacterial and fungal microbiomes in the gut of adult honeybees

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Matteo Callegari ◽  
Elena Crotti ◽  
Marco Fusi ◽  
Ramona Marasco ◽  
Elena Gonella ◽  
...  
Keyword(s):  
Gut Microbiome ◽  
Bacterial Phylotypes ◽  
Specific Variable ◽  
The Core ◽  
Physico Chemical ◽  
Metabolic Conditions ◽  
Chemical Conditions ◽  
And Behavior

AbstractThe core gut microbiome of adult honeybee comprises a set of recurring bacterial phylotypes, accompanied by lineage-specific, variable, and less abundant environmental bacterial phylotypes. Several mutual interactions and functional services to the host, including the support provided for growth, hormonal signaling, and behavior, are attributed to the core and lineage-specific taxa. By contrast, the diversity and distribution of the minor environmental phylotypes and fungal members in the gut remain overlooked. In the present study, we hypothesized that the microbial components of forager honeybees (i.e., core bacteria, minor environmental phylotypes, and fungal members) are compartmentalized along the gut portions. The diversity and distribution of such three microbial components were investigated in the context of the physico-chemical conditions of different gut compartments. We observed that changes in the distribution and abundance of microbial components in the gut are consistently compartment-specific for all the three microbial components, indicating that the ecological and physiological interactions among the host and microbiome vary with changing physico-chemical and metabolic conditions of the gut.

scholarly journals A physico-chemical model to study the ion density distribution in the inner coma of comet C/2016 R2 (Pan-STARRS)

2020 ◽  
Author(s):  
Susarla Raghuram ◽  
Anil Bhardwaj ◽  
Damien Hutsemékers ◽  
Cyrielle Opitom ◽  
Jean Manfroid ◽  
...  
Keyword(s):  
Density Distribution ◽  
Electron Impact ◽  
Emission Intensity ◽  
Impact Ionization ◽  
Excitation Source ◽  
Resonance Fluorescence ◽  
Ion Density ◽  
Physico Chemical ◽  
Intensity Ratios ◽  
Ion Emission

Abstract The recent observations show that comet C/2016 R2 (Pan-Starrs) has a unique and peculiar composition when compared with several other comets observed at 2.8 au heliocentric distance. Assuming solar resonance fluorescence is the only excitation source, the observed ionic emission intensity ratios are used to constrain the corresponding neutral abundances in this comet. We developed a physico-chemical model to study the ion density distribution in the inner coma of this comet by accounting for photon and electron impact ionization of neutrals, charge exchange and proton transfer reactions between ions and neutrals, and electron-ion thermal recombination reactions. Our calculations show that CO$_2^+$ and CO+ are the major ions in the inner coma, and close to the surface of nucleus CH3OH+, CH3OH$_2^+$ and O$_2^+$ are also important ions. By considering various excitation sources, we also studied the emission mechanisms of different excited states of CO+, CO$_2^+$, N$_2^+$, and H2O+. We found that the photon and electron impact ionization and excitation of corresponding neutrals significantly contribute to the observed ionic emissions for radial distances smaller than 300 km and at larger distances, solar resonance fluorescence is the major excitation source. Our modelled ion emission intensity ratios are consistent with the ground-based observations. Based on the modelled emission processes, we suggest that the observed ion emission intensity ratios can be used to derive the neutral composition in the cometary coma only when the ion densities are significantly controlled by photon and photoelectron impact ionization of neutrals rather than by the ion-neutral chemistry.

scholarly journals Dissolved organic nutrients at the interface of fresh and marine waters: flow regime changes, biogeochemical cascades and picocyanobacterial blooms—the example of Florida Bay, USA

2021 ◽  
Author(s):  
Patricia M. Glibert ◽  
Cynthia A. Heil ◽  
Christopher J. Madden ◽  
Stephen P. Kelly
Keyword(s):  
Water Quality ◽  
Anthropogenic Activities ◽  
Florida Bay ◽  
Climate Conditions ◽  
Regime Changes ◽  
Physico Chemical ◽  
Organic Nutrients ◽  
High Concentrations ◽  
Chemical Conditions ◽  
Favorable Conditions

AbstractThe availability of dissolved inorganic and organic nutrients and their transformations along the fresh to marine continuum are being modified by various natural and anthropogenic activities and climate-related changes. Subtropical central and eastern Florida Bay, located at the southern end of the Florida peninsula, is classically considered to have inorganic nutrient conditions that are in higher-than-Redfield ratio proportions, and high levels of organic and chemically-reduced forms of nitrogen. However, salinity, pH and nutrients, both organic and inorganic, change with changes in freshwater flows to the bay. Here, using a time series of water quality and physico-chemical conditions from 2009 to 2019, the impacts of distinct changes in managed flow, drought, El Niño-related increases in precipitation, and intensive storms and hurricanes are explored with respect to changes in water quality and resulting ecosystem effects, with a focus on understanding why picocyanobacterial blooms formed when they did. Drought produced hyper-salinity conditions that were associated with a seagrass die-off. Years later, increases in precipitation resulting from intensive storms and a hurricane were associated with high loads of organic nutrients, and declines in pH, likely due to high organic acid input and decaying organic matter, collectively leading to physiologically favorable conditions for growth of the picocyanobacterium, Synechococcus spp. These conditions, including very high concentrations of NH4+, were likely inhibiting for seagrass recovery and for growth of competing phytoplankton or their grazers. Given projected future climate conditions, and anticipated cycles of drought and intensive storms, the likelihood of future seagrass die-offs and picocyanobacterial blooms is high.

scholarly journals Croonian lecture.—Observations on isolated nerve. Electrical changes a measure of physico-chemical change

1896 ◽  
Vol 59 (353-358) ◽  
pp. 308-312
Keyword(s):  
Chemical Change ◽  
Physico Chemical ◽  
Chemical Conditions

The present investigation arises from experiments undertaken to determine autographically the varying relations between the magnitude of electrical change and the magnitude of stimulation in nerve under various chemical conditions.

SECONDARY CHANGES IN CARBONATE ROCKS OF OIL AND GAS COMPLEXES

2020 ◽  
pp. 18-23
Author(s):  
M.A. Tugarova
Keyword(s):  
Carbonate Rocks ◽  
Oil And Gas ◽  
Carbonate Reservoirs ◽  
Fundamental Importance ◽  
Schematic Diagram ◽  
Reservoir Properties ◽  
Physico Chemical ◽  
Chemical Conditions ◽  
First Time

The article considers the secondary transformations of carbonate rocks of oil and gas complexes, which are of fundamental importance in the formation of reservoir properties. For the first time, a schematic diagram, illustrating the regularities of secondary processes in carbonate reservoirs and their relationship with the physico-chemical conditions of the stratosphere is proposed.

scholarly journals Interstellar and interplanetary solids in the laboratory

2015 ◽  
Vol 11 (A29B) ◽  
pp. 416-419 ◽  
Author(s):  
Emmanuel Dartois ◽  
Ivan Alata ◽  
Cécile Engrand ◽  
Rosario Brunetto ◽  
Jean Duprat ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Environmental Parameters ◽  
Interstellar Matter ◽  
Additional Information ◽  
Set Constraints ◽  
Physico Chemical ◽  
Space Environments ◽  
Chemical Conditions ◽  
Extraterrestrial Material ◽  
Shed Light

AbstractThe composition of interstellar matter is driven by environmental parameters and results from extreme interstellar medium physico-chemical conditions. Astrochemists must rely on remote observations to monitor and analyze the interstellar solids composition. They bring additional information from the study of analogues produced in the laboratory, placed in simulated space environments. Planetologists and cosmochemists access and spectroscopically examine collected extraterrestrial material in the laboratory. Diffuse interstellar medium and molecular clouds observations set constraints on the composition of organic solids that can then be compared with collected extraterrestrial materials analyses, to shed light on their possible links.

scholarly journals Study Of Impacts Of Oil Spill On The Sundarbans Mangrove Forest Of Bangladesh

2015 ◽  
Vol 41 (1) ◽  
pp. 75-94 ◽  
Author(s):  
Abdullah Harun Chowdhury ◽  
Md Ali Akber
Keyword(s):  
Oil Spill ◽  
Oil Content ◽  
World Heritage Site ◽  
Heritage Site ◽  
Physico Chemical ◽  
Common Birds ◽  
Chemical Conditions ◽  
Monitor Lizards ◽  
Total Study Area ◽  
The Sundarbans

Studies were carried out on the recent oil spill in the Sundarbans of Bangladesh to findout the immediate impacts on the ecosystem of the Sundarbans after oil spilling. Morethan 500 km2 areas out of the total study area have been affected seriously by the oil spillcontamination on 9 December 2014. Recorded data of the physico-chemical conditions,oil content, productivity, diversity and abundance of phyto-zooplankton and benthos ofwater, and oil content in soil indicate that the water and soil of the Eastern part of theSundarbans were polluted by the oil contamination. Results also indicate that seedlings,mangrove algae, eggs and hatchlings of commercially valuable fishes, mudskippers, mudcrabs, snails, monitor lizards were affected due to oil spill. Regeneration of the Sundritrees; intertidal zone bird - ‘Masked finfoot’, common birds, fishing cat, otter, dolphins,crocodile would be affected due to the oil spill. Long term monitoring, in depth researchand proper implementation of all rules and regulations are necessary to save the fragileecosystem of the Sundarbans-the UNESCO declared world heritage site. Asiat. Soc. Bangladesh, Sci. 41(1): 75-94, June 2015

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