scholarly journals Underwater Holographic Sensor for Plankton Studies In Situ Including Accompanying Measurements

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4863
Author(s):  
Victor Dyomin ◽  
Alexandra Davydova ◽  
Igor Polovtsev ◽  
Alexey Olshukov ◽  
Nikolay Kirillov ◽  
...  
Keyword(s):  
World Ocean ◽  
Field Tests ◽  
Field Measurements ◽  
Measuring Systems ◽  
Water Turbidity ◽  
Background Data ◽  
Average Size ◽  
Size Dispersion

The paper presents an underwater holographic sensor to study marine particles—a miniDHC digital holographic camera, which may be used as part of a hydrobiological probe for accompanying (background) measurements. The results of field measurements of plankton are given and interpreted, their verification is performed. Errors of measurements and classification of plankton particles are estimated. MiniDHC allows measurement of the following set of background data, which is confirmed by field tests: plankton concentration, average size and size dispersion of individuals, particle size distribution, including on major taxa, as well as water turbidity and suspension statistics. Version of constructing measuring systems based on modern carriers of operational oceanography for the purpose of ecological diagnostics of the world ocean using autochthonous plankton are discussed. The results of field measurements of plankton using miniDHC as part of a hydrobiological probe are presented and interpreted, and their verification is carried out. The results of comparing the data on the concentration of individual taxa obtained using miniDHC with the data obtained by the traditional method using plankton catching with a net showed a difference of no more than 23%. The article also contains recommendations for expanding the potential of miniDHC, its purpose indicators, and improving metrological characteristics.

Strategies of In Situ Generated Magnesium Catalysis in Asymmetric Reactions

Synlett ◽  
2021 ◽  
Author(s):  
Dongxu Yang ◽  
Linqing Wang
Keyword(s):  
Asymmetric Synthesis ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Asymmetric Reactions ◽  
Chiral Ligands ◽  
Alkaline Earth Metal ◽  
Enantioselective Reactions ◽  
Earth's Crust

AbstractMagnesium (Mg) is a cheap, non-toxic, and recyclable alkaline earth metal that constitutes about 2% weight in the Earth’s crust. The use of magnesium catalysts to forge chiral moieties in molecules is highly attractive. Based on our work in recent years, we describe the current progress in the development of in situ generated magnesium catalysts and their application in asymmetric synthesis. In this perspective, a critically concise classification of in situ generated magnesium catalytic modes, with relevant examples, is presented, and representative mechanisms of each category are discussed. Building on the established diverse strategies, one can foresee that more innovative and structurally creative magnesium catalysts that are generated in situ will be developed to overcome more formidable challenges of catalytic enantioselective reactions.1 Introduction2 Magnesium Catalysts Generated in Situ from Chiral Ligands Containing Dual Reactive Hydrogens3 Magnesium Catalysts Generated in Situ from Monoanionic Chiral Ligands4 Bimetallic and Polymetallic Magnesium Catalysts Assembled in Situ5 Summary and Outlook

scholarly journals Laboratory and In Situ Determination of Hydraulic Conductivity and Their Validity in Transient Seepage Analysis

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1131
Author(s):  
Soonkie Nam ◽  
Marte Gutierrez ◽  
Panayiotis Diplas ◽  
John Petrie
Keyword(s):  
Hydraulic Conductivity ◽  
Field Measurements ◽  
Natural Soil ◽  
In Situ Tests ◽  
Seepage Analysis ◽  
Soil Deposits ◽  
Seepage Modeling ◽  
Sample Disturbance

This paper critically compares the use of laboratory tests against in situ tests combined with numerical seepage modeling to determine the hydraulic conductivity of natural soil deposits. Laboratory determination of hydraulic conductivity used the constant head permeability and oedometer tests on undisturbed Shelby tube and block soil samples. The auger hole method and Guelph permeameter tests were performed in the field. Groundwater table elevations in natural soil deposits with different hydraulic conductivity values were predicted using finite element seepage modeling and compared with field measurements to assess the various test results. Hydraulic conductivity values obtained by the auger hole method provide predictions that best match the groundwater table’s observed location at the field site. This observation indicates that hydraulic conductivity determined by the in situ test represents the actual conditions in the field better than that determined in a laboratory setting. The differences between the laboratory and in situ hydraulic conductivity values can be attributed to factors such as sample disturbance, soil anisotropy, fissures and cracks, and soil structure in addition to the conceptual and procedural differences in testing methods and effects of sample size.

Standoff femtosecond filament-induced breakdown spectroscopy for classification of geological materials

2020 ◽  
Vol 35 (12) ◽  
pp. 3007-3020
Author(s):  
S. Abdul Kalam ◽  
S. V. Balaji Manasa Rao ◽  
M. Jayananda ◽  
S. Venugopal Rao
Keyword(s):  
Geological Materials ◽  
Breakdown Spectroscopy ◽  
Remote Locations

Femtosecond (fs) filaments delivering substantial peak intensities at remote locations are exploited in classification of geological materials together with in situ /standoff investigations.

Influence of the Dispersion of the Size of the Si Nanocrystals on their Emission Spectra

1994 ◽  
Vol 358 ◽  
Author(s):  
J. B. Khurgin ◽  
E. W. Forsythe ◽  
S. I. Kim ◽  
B. S. Sywe ◽  
B. A. Khan ◽  
...  
Keyword(s):  
Systematic Study ◽  
Quantum Confinement ◽  
Emission Spectra ◽  
Emission Peak ◽  
Nanocrystal Size ◽  
Pl Spectra ◽  
Si Nanocrystals ◽  
Average Size ◽  
Size Dispersion ◽  
Confinement Model

ABSTRACTA systematic study of the PL spectra of Si quantum nanocrystals in the SiO2 matrix has been performed. The results have been fitted to a quantum-confinement model that includes the nanocrystal size dispersion rather than a specific size of the nanocrystal. This serves as a strong confirmation of the confinement-induced nature of the PL. It has been shown that if the dispersion is taken into account, the position of the emission peak as well as the PL width can always be correlated with the average size of the nanocrystal.

Molecular Cytogenetic Classification of Down Syndrome and Screening of Somatic Aneuploidy in Mothers

2021 ◽  
pp. 1-9
Author(s):  
Sushil Kumar Jaiswal ◽  
Ashok Kumar ◽  
Amit Kumar Rai
Keyword(s):  
Down Syndrome ◽  
Peripheral Blood ◽  
Trisomy 21 ◽  
Health Management ◽  
Chromosome 21 ◽  
Robertsonian Translocations ◽  
Significant Difference ◽  
And Control

Down Syndrome (DS) caused by trisomy 21 results in various congenital and developmental complications in children. It is crucial to cytogenetically diagnose the DS cases early for their proper health management and to reduce the risk of further DS childbirths in mothers. In this study, we performed a cytogenetic analysis of 436 suspected DS cases using karyotyping and fluorescent in situ hybridization. We detected free trisomies (95.3%), robertsonian translocations (2.4%), isochromosomes (0.6%), and mosaics (1.2%). We observed a slightly higher incidence of DS childbirth in younger mothers compared to mothers with advanced age. We compared the somatic aneuploidy in peripheral blood of mothers having DS children (MDS) and control mothers (CM) to identify biomarkers for predicting the risk for DS childbirths. No significant difference was observed. After induced demethylation in peripheral blood cells, we did not observe a significant difference in the frequency of aneuploidy between MDS and CM. In conclusion, free trisomy 21 is the most common type of chromosomal abnormality in DS. A small number of DS cases have translocations and mosaicism of chromosome 21. Additionally, somatic aneuploidy in the peripheral blood from the mother is not an effective marker to predict DS childbirths.

Assessment of Moisture Content in Sandy Beach Environments from Multispectral Satellite Imagery

2021 ◽  
Author(s):  
Julie Paprocki ◽  
Nina Stark ◽  
Hans C Graber ◽  
Heidi Wadman ◽  
Jesse E McNinch
Keyword(s):  
Moisture Content ◽  
Laboratory Data ◽  
Field Measurements ◽  
Weather Conditions ◽  
Sandy Beaches ◽  
Percent Error ◽  
Moisture Contents ◽  
Multispectral Satellite Imagery ◽  
Factor C

A framework for estimating moisture content from satellite-based multispectral imagery of sandy beaches was tested under various site conditions and sensors. It utilizes the reflectance of dry soil and an empirical factor c relating reflectance and moisture content for specific sediment. Here, c was derived two ways: first, from in-situ measurements of moisture content and average NIR image reflectance; and second, from laboratory-based measurements of moisture content and spectrometer reflectance. The proposed method was tested at four sandy beaches: Duck, North Carolina, and Cannon Beach, Ocean Cape, and Point Carrew, Yakutat, Alaska. Both measured and estimated moisture content profiles were impacted by site geomorphology. For profiles with uniform slopes, moisture contents ranged from 3.0%-8.0% (Zone 1) and from 8.0%-23.0% (Zone 2). Compared to field measurements, the moisture contents estimated using c calibrated from in-situ and laboratory data resulted in percent error of 3.6%-44.7% and 2.7%-58.6%, respectively. The highest percent error occurred at the transition from Zone 1 to Zone 2. Generally, moisture contents were overestimated in Zone 1 and underestimated in Zone 2, but followed the expected trends based on field measurements. When estimated moisture contents in Zone 1 exceeded 10%, surface roughness, debris, geomorphology, and weather conditions were considered.

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