Exposed facets dictate microbial methylation potential of mercury sulfide nanoparticles

2020 ◽  
Author(s):  
Li Tian ◽  
Wenyu Guan ◽  
Yunyun Ji ◽  
Xin He ◽  
Wei Chen ◽  
...  
Keyword(s):  
Contaminated Soils ◽  
Early Stage ◽  
Theoretical Calculations ◽  
Desulfovibrio Desulfuricans ◽  
Mercury Contamination ◽  
Nanocrystal Growth ◽  
Subsequent Effect ◽  
Microbial Methylation ◽  
Methylmercury Production ◽  
Exposed Facets

Abstract Methylmercury formation is the major concern of global mercury contamination. Accurate prediction of methylmercury production remains elusive due in part to the lack of mechanistic understanding of microbial methylation potential of particulate-phase mercury. Here we show that the methylation potential of nanoparticulate metacinnabar, which is formed during the early stage of mercury mineralization and is ubiquitous in contaminated soils and sediments, is determined by its exposed facets. Nanoparticulate metacinnabar with higher (111) content exhibits significantly greater affinity to the methylating bacterium Desulfovibrio desulfuricans ND132, leading to higher methylmercury production. This is likely attributable to the favored binding between the (111) facet and the protein transporter responsible for mercury cellular uptake prior to methylation. The (111) facet of metacinnabar tends to diminish during nanocrystal growth, but natural ligands alleviate this process by preferentially adsorbing to the (111) facet (verified with adsorption experiments using facet-engineered model materials coupled with theoretical calculations). This facet evolution of metacinnabar and its subsequent effect on mercury bioavailability explain the intriguing observation that methylation potential of nanoparticulate mercury is surface-area-independent. Our discovery provides new mechanistic insights for interfacial processes involved in nanoparticle−microorganism interactions that have important implications for understanding the environmental behavior of mercury and other nutrient or toxic elements associated with widely present crystalline nanoparticles.

scholarly journals Assessment of Mercury-Polluted Soils Adjacent to an Old Mercury-Fulminate Production Plant

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
M. Camps Arbestain ◽  
L. Rodríguez-Lado ◽  
M. Bao ◽  
F. Macías
Keyword(s):  
Surface Waters ◽  
Contaminated Soils ◽  
Flow Direction ◽  
Surface Flow ◽  
Mercury Contamination ◽  
Production Plant ◽  
Polluted Soils ◽  
Flow Through ◽  
Contamination Of Soils ◽  
Surrounding Soil

Mercury contamination of soils and vegetation close to an abandoned Hg-fulminate production plant was investigated. Maximum concentrations of Hg (>6.5 gkg−1soil) were found in the soils located in the area where the wastewater produced during the washing procedures carried out at the production plant used to be discharged. A few meters away from the discharge area, Hg concentrations decreased to levels ranging between 1 and 5 gkg−1, whereas about 0.5 ha of the surrounding soil to the NE (following the dominant surface flow direction) contained between 0.1 and 1 gkg−1. Mercury contamination of soils was attributed (in addition to spills from Hg containers) to (i) Hg volatilization with subsequent condensation in cooler areas of the production plant and in the surrounding forest stands, and (ii) movement of water either by lateral subsurface flow through the contaminated soils or by heavy runoff to surface waters.

scholarly journals Quantification of Hydrocarbon Abundance in Soils Using Deep Learning with Dropout and Hyperspectral Data

2019 ◽  
Vol 11 (16) ◽  
pp. 1938 ◽  
Author(s):  
Asmau M. Ahmed ◽  
Olga Duran ◽  
Yahya Zweiri ◽  
Mike Smith
Keyword(s):  
Deep Learning ◽  
Contaminated Soils ◽  
Early Stage ◽  
Imaging Techniques ◽  
Rapid Identification ◽  
Hyperspectral Data ◽  
Learning Approach ◽  
Backpropagation Algorithm ◽  
Average Mean Square Error ◽  
Deep Learning Neural Network

Terrestrial hydrocarbon spills have the potential to cause significant soil degradation across large areas. Identification and remedial measures taken at an early stage are therefore important. Reflectance spectroscopy is a rapid remote sensing method that has proven capable of characterizing hydrocarbon-contaminated soils. In this paper, we develop a deep learning approach to estimate the amount of Hydrocarbon (HC) mixed with different soil samples using a three-term backpropagation algorithm with dropout. The dropout was used to avoid overfitting and reduce computational complexity. A Hyspex SWIR 384 m camera measured the reflectance of the samples obtained by mixing and homogenizing four different soil types with four different HC substances, respectively. The datasets were fed into the proposed deep learning neural network to quantify the amount of HCs in each dataset. Individual validation of all the dataset shows excellent prediction estimation of the HC content with an average mean square error of ~ 2 . 2 × 10 - 4 . The results with remote sensed data captured by an airborne system validate the approach. This demonstrates that a deep learning approach coupled with hyperspectral imaging techniques can be used for rapid identification and estimation of HCs in soils, which could be useful in estimating the quantity of HC spills at an early stage.

scholarly journals Effects of Cellular Sorption on Mercury Bioavailability and Methylmercury Production by Desulfovibrio desulfuricans ND132

2016 ◽  
Vol 50 (24) ◽  
pp. 13335-13341 ◽  
Author(s):  
Yu-Rong Liu ◽  
Xia Lu ◽  
Linduo Zhao ◽  
Jing An ◽  
Ji-Zheng He ◽  
...  
Keyword(s):  
Desulfovibrio Desulfuricans ◽  
Methylmercury Production

scholarly journals Low Momentum Direct Photon Measurement

2018 ◽  
Vol 182 ◽  
pp. 02041
Author(s):  
Wenqing Fan
Keyword(s):  
Early Stage ◽  
Theoretical Calculations ◽  
Theoretical Models ◽  
Gluon Plasma ◽  
Direct Photons ◽  
Electron Positron ◽  
Large Yield ◽  
Hadron Gas ◽  
200 Gev ◽  
Azimuthal Asymmetries

Direct photons have long been considered as golden probes to study the properties of the Quark Gluon Plasma (QGP). They do not interact strongly with the medium and are produced at all stages of the collision, hence carrying information of the entire evolution of the system to the detectors. The PHENIX experiment discovered a large excess of low pT photons in Au+Au collisions at √sNN = 200 GeV compared to reference p+p collisions, which has been interpreted as thermal radiation from the QGP and hadron gas medium. At the same time, the excess photons show a large elliptic and triangular flow. These results are challenging for the current theoretical models to describe simultaneously, because on one hand the large yield suggests early stage emissions when the temperature is high, on the other hand the large anisotropy is expected to be formed only at later stages of the collision when the system has cooled off and the thermal photon production rate is expected to be smaller. Using a variety of high statistics datasets across different collision systems and energies in PHENIX, simultaneous analyses of yields and azimuthal asymmetries of direct photons with higher precision are performed to provide more constraints to the theoretical calculations. In this talk, we will present recent results on low pT direct photons measured via their external conversions to electron-positron pairs, including new results from Au+Au at lower beam energies of 39 and 62.4 GeV, as well as Cu+Cu at 200GeV.

Bacterial growth phase influences methylmercury production by the sulfate-reducing bacterium Desulfovibrio desulfuricans ND132

2011 ◽  
Vol 409 (19) ◽  
pp. 3943-3948 ◽  
Author(s):  
Abir Biswas ◽  
Scott C. Brooks ◽  
Carrie L. Miller ◽  
Jennifer J. Mosher ◽  
Xiangping L. Yin ◽  
...  
Keyword(s):  
Bacterial Growth ◽  
Growth Phase ◽  
Desulfovibrio Desulfuricans ◽  
Sulfate Reducing ◽  
Methylmercury Production

scholarly journals Adsorption Mechanism of Typical Gases Exhaled by Lung Cancer Patients on the Anatase TiO2(101) Surface

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Qianqian Wan ◽  
Yancheng Xu ◽  
Xiaoxing Zhang
Keyword(s):  
Lung Cancer ◽  
Cancer Patients ◽  
Density Functional ◽  
Early Stage ◽  
Theoretical Calculations ◽  
Density Functional Theory Method ◽  
Cancer Prognosis ◽  
Frontier Molecular Orbital ◽  
Nanotube Arrays ◽  
Lung Cancer Patients

Considerable researches have proved that, to a great extent, high death rate of lung cancer is on account of its crypticity in the early stage, and detection of typical exhaled gases of possible patients has emerged as an effective and workable method to realize the prognosis of lung cancer. In this paper, the adsorption of the three typical exhaled components, namely, C6H6, C8H8, and C5H8, of lung cancer patients on the anatase TiO2(101) surface was simulated based on the density functional theory method in order to recommend TiO2nanotube arrays as sensing materials to fulfill this aim. Analysis based on adsorbing parameters, frontier molecular orbital theory, and density of states congruously implies that the anatase TiO2(101) surface possesses certain sensitivity to these three gases, especially to C8H8which possesses the best activity to be adsorbed on the proposed surface. Our experimental study showed great consensus with the theoretical calculations. Therefore, TiO2nanotube arrays can be applied as proper gas-sensing material for the preparation of lung cancer prognosis sensors as a family device to realize the simple and convenient detection of lung cancer in our daily life.

Research highlights: elucidation of biogeochemical factors influencing methylmercury production

2015 ◽  
Vol 17 (10) ◽  
pp. 1708-1711 ◽  
Author(s):  
Paul R. Erickson ◽  
Vivian S. Lin
Keyword(s):  
Nutrient Availability ◽  
Mercury Contamination ◽  
Factors Influencing ◽  
Biogeochemical Factors ◽  
Methylmercury Production ◽  
Demethylation Activity

This Highlight features recent articles that examine in detail the effects of nutrient availability on the methylation–demethylation activity of microorganisms living in sediment with mercury contamination.

scholarly journals Green Remediation And Physiological Responses of Plants To Metal-Contaminated Soils In Jinchang Mining Areas, Western Desert, China

2021 ◽  
Author(s):  
Changming Li ◽  
Xisheng Tai ◽  
Guohua Chang ◽  
Zidong Wan ◽  
Jingwen Fu ◽  
...  
Keyword(s):  
Contaminated Soils ◽  
Early Stage ◽  
Local Environment ◽  
Mining Area ◽  
Western Desert ◽  
Western China ◽  
Atriplex Canescens ◽  
Mining Areas ◽  
Metal Mine ◽  
Green Remediation

Abstract Jinchang mining area, as a metal mine with a long history of arid and semi-arid mining in western China, has brought a great risk of heavy metal pollution to the local environment. In this experiment, tailings, slag and native soil are mixed in equal proportions for the pot experiment settings. 9 species of sand plants unique to the arid region of the western inland were planted to screen the varieties with green remediation value. After six months of plant growth, the concentration of Zn in the plant was the highest, ranging from 103.27 to 467.63mg/kg, followed by Cu, ranging from 25.07 to 200.35mg/kg. In the early stage (2 months), POD was the main defense, and in the later stage (4\6 months), SOD and CAT were the main defense, accompanied by unknown proteins up-regulated. The results of net photosynthetic rate showed that it was inhibited by metal stress in the early stage, and it was high in the late stage to provide material basis for the accumulation and secretion of adaptable and resistant substances. Seven species of plants, such as Suaeda glauca, Bassia scoparia, Halogeton glomeratus, Kalidium foliatum, Medicago falcata, Atriplex canescens, Artemisia desertorum can be used as enrichment materials for Zn and Cu. While, Atriplex canescens has the highest metal enrichment potential, and can be used as a planting variety to enrich Cd, Ni and Pb in a broad spectrum of metals including Zn and Cu. This study lays a solid scientific foundation for green remediation of contaminated soil in arid desert area of western China.

Bone Marrow Pressure Changes under an Inflatable Tourniquet

HAND ◽  
1983 ◽  
Vol os-15 (1) ◽  
pp. 3-8 ◽  
Author(s):  
J. C. Griffiths ◽  
M. Sankarankutty
Keyword(s):  
Blood Pressure ◽  
Bone Marrow ◽  
Early Stage ◽  
Theoretical Calculations ◽  
Elastic Solid ◽  
Shear Stresses ◽  
Fluid Shift ◽  
Intramedullary Pressure ◽  
Tissue Interface ◽  
Pressure Changes

Theoretical calculations suggest that under a limb tourniquet, the pressure at the bone/tissue interface is greater than it is more peripherally. The central bony core must be incompressible for this hypothesis to be correct. Experiments designed to measure the intramedullary pressure confirm that this pressure does not rise at tourniquet pressures above the systolic blood pressure. It has also been suggested that shear stresses are the most likely cause of nerve damage under a tourniquet but this depends on the conversion of the tissue under compression into a fibro-elastic solid. This is likely to occur when all fluid has been driven out. From the experiments such a fluid shift does not seen to occur via the intramedullary cavity but it must nevertheless occur at an early stage of rising tourniquet pressure, probably by fluid shift through the veins proximal and distal to the tourniquet.

scholarly journals The Reaction of Aminonitriles with Aminothiols: A Way to Thiol-Containing Peptides and Nitrogen Heterocycles in the Primitive Earth Ocean

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 47 ◽  
Author(s):  
Ibrahim Shalayel ◽  
Seydou Coulibaly ◽  
Kieu Ly ◽  
Anne Milet ◽  
Yannick Vallée
Keyword(s):  
Hydrogen Cyanide ◽  
Early Stage ◽  
Theoretical Calculations ◽  
Membered Ring ◽  
Small Peptides ◽  
Primitive Earth ◽  
Peptide Bonds ◽  
Heterocyclic Molecules ◽  
Strecker Reaction ◽  
Life On Earth

The Strecker reaction of aldehydes with ammonia and hydrogen cyanide first leads to α-aminonitriles, which are then hydrolyzed to α-amino acids. However, before reacting with water, these aminonitriles can be trapped by aminothiols, such as cysteine or homocysteine, to give 5- or 6-membered ring heterocycles, which in turn are hydrolyzed to dipeptides. We propose that this two-step process enabled the formation of thiol-containing dipeptides in the primitive ocean. These small peptides are able to promote the formation of other peptide bonds and of heterocyclic molecules. Theoretical calculations support our experimental results. They predict that α-aminonitriles should be more reactive than other nitriles, and that imidazoles should be formed from transiently formed amidinonitriles. Overall, this set of reactions delineates a possible early stage of the development of organic chemistry, hence of life, on Earth dominated by nitriles and thiol-rich peptides (TRP).

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