scholarly journals A Modified Method to Calculate Dual Isotope Slopes for the Natural Attenuation of Organic Pollutants in the Environment

2021 ◽  
Author(s):  
Jin-Ru Feng ◽  
Hong-Gang Ni
Keyword(s):  
Reaction Mechanism ◽  
Isotope Fractionation ◽  
Isotope Analysis ◽  
Aerobic Biodegradation ◽  
Two Dimensional ◽  
Data Set ◽  
Dual Isotope ◽  
Sulfate Reducing ◽  
Modified Method ◽  
Novel Method

Abstract Two-dimensional compound specific isotope analysis has become a powerful tool to distinguish reaction mechanism. Lambda (Λ), an essential and important parameter for processing two-dimensional isotope fractionation data, is specific to a reaction mechanism. In the present article, we modified the existing algorithms for Lambdas based on the review of the current methods. Specifically, through regressing [(1000+δE0,2)*(n1*x2)*ΔδEbulk,1] versus [(1000+δE0,1)*(n2*x1)*ΔδEbulk,2] by York method, a novel method was developed to calculate Λs. The improved method eliminates both the influence of non-reacting position and the initial isotope signatures. Furthermore, this method retains the advantages of two-dimension isotope plot, which eliminates contributions from commitment to catalysis, no need to determine fraction of remaining substrate and can be constructed even from filed data. At the same time, one sample t test is applied to generate 95% confidence interval of data set of Λris for various reaction mechanisms. The range of 5.67-24.8, 8.54-9.80, 0.51-8.35, 25.2-36.8, 7.09-21.9 are responsible for oxidation of C-H bonds (ZC=1, ZH=3), oxidation of C-H bonds (ZC=1,ZH=4), aerobic biodegradation of benzene (ZC=6,ZH=6), methanogenic or sulfate-reducing biodegradation of benzene (ZC=6,ZH=6), and nitrate-reducing biodegradation of benzene (ZC=6,ZH=6). The accumulation and correction of these values will make the data measured in the field easier to interpret.

scholarly journals Carbon Isotope Fractionation during Anaerobic Degradation of Methyl tert-Butyl Ether under Sulfate-Reducing and Methanogenic Conditions

2006 ◽  
Vol 72 (2) ◽  
pp. 1157-1163 ◽  
Author(s):  
Piyapawn Somsamak ◽  
Hans H. Richnow ◽  
Max M. Häggblom
Keyword(s):  
Carbon Isotope ◽  
Anaerobic Degradation ◽  
Isotope Fractionation ◽  
Isotope Analysis ◽  
Methyl Tert Butyl Ether ◽  
Public Attention ◽  
Butyl Ether ◽  
Carbon Isotope Fractionation ◽  
Sulfate Reducing ◽  
Mtbe Degradation

ABSTRACT Methyl tert-butyl ether (MTBE), an octane enhancer and a fuel oxygenate in reformulated gasoline, has received increasing public attention after it was detected as a major contaminant of water resources. Although several techniques have been developed to remediate MTBE-contaminated sites, the fate of MTBE is mainly dependent upon natural degradation processes. Compound-specific stable isotope analysis has been proposed as a tool to distinguish the loss of MTBE due to biodegradation from other physical processes. Although MTBE is highly recalcitrant, anaerobic degradation has been demonstrated under different anoxic conditions and may be an important process. To accurately assess in situ MTBE degradation through carbon isotope analysis, carbon isotope fractionation during MTBE degradation by different cultures under different electron-accepting conditions needs to be investigated. In this study, carbon isotope fractionation during MTBE degradation under sulfate-reducing and methanogenic conditions was studied in anaerobic cultures enriched from two different sediments. Significant enrichment of 13C in residual MTBE during anaerobic biotransformation was observed under both sulfate-reducing and methanogenic conditions. The isotopic enrichment factors (ε) estimated for each enrichment were almost identical (−13.4 to −14.6; r 2 = 0.89 to 0.99). A ε value of −14.4 ± 0.7 was obtained from regression analysis (r 2 = 0.97, n = 55, 95% confidence interval), when all data from our MTBE-transforming anaerobic cultures were combined. The similar magnitude of carbon isotope fractionation in all enrichments regardless of culture or electron-accepting condition suggests that the terminal electron-accepting process may not significantly affect carbon isotope fractionation during anaerobic MTBE degradation.

Quantifying the contribution of three competing pathways to total degradation in groundwater by a triple-isotope analysis approach

2020 ◽  
Author(s):  
Martin Thullner ◽  
Florian Centler ◽  
Thomas Hofstetter
Keyword(s):  
Stable Isotope ◽  
Isotope Fractionation ◽  
Environmental Science ◽  
Isotope Analysis ◽  
Enrichment Factors ◽  
Theoretical Concept ◽  
Degradation Pathways ◽  
Theoretical Concepts ◽  
Dual Isotope ◽  
Stable Isotope Fractionation

<p>In groundwater and other environmental compartments, compound-specific stable isotope analysis (CSIA) has been used for the determination of specific degradation pathways by analyzing the stable isotopes of two elements. This ‘dual-isotope’ or two-dimensional isotope’ analysis also allows for an estimation of the contribution of two different pathways contributing both to the overall degradation and stable isotope fractionation. Heterogeneous groundwater flow patterns lead to some yet acceptable uncertainities in the results of this method.  Recent CSIA approaches also allow for investigating the simultaneous stable isotope fractionation effects for three different elements. Such information on the stable isotope fractionation of three different elements of a degradable compound could be used for a quantitative analysis of the contribution of different degradation pathways in systems with three different pathways, but up to know there is no theoretical concepts providing such quantitative estimate.</p><p>The aim of the present study is to overcome this shortage and to present such theoretical concept for the quantification of single pathway contribution to the overall biodegradation in groundwater and other systems with three parallel degradation pathways. For this purpose the approach of Centler et al. (2013) for the analysis of dual-isotope analysis has been expanded to consider the fractionation of three different elements affected by three different pathways. The obtained analytical expression allows for the quantification of each pathway to total degradation based stable isotope enrichment factors and measured stable isotope signatures. The applicability of the concept is demonstrated using data from Wijker et al. (2013).</p><p> </p><p>Centler, F., Hesse, F., and Thullner, M. (2013) Journal of Contaminant Hydrology, 152, 97-116.</p><p>Wijker, R. S., Bolotin, J., Nishino, S. F., Spain, J. C., and Hofstetter, T. B. (2013) Environmental Science & Technology, 47, 6872-6883.</p><p> </p>

scholarly journals Effect of Metabolic Constraints on the Observable Isotope Fractionation Associated with Aerobic Biodegradation of Hexachlorocyclohexanes

2019 ◽  
Author(s):  
Iris E. Schilling ◽  
Hans-Peter E. Kohler ◽  
Thomas Hofstetter
Keyword(s):  
Contaminated Soils ◽  
Isotope Fractionation ◽  
Isotope Analysis ◽  
Enrichment Factors ◽  
Aerobic Biodegradation ◽  
Side Reactions ◽  
Preferential Formation ◽  
Soils And Sediments ◽  
Competitive Behaviour ◽  
Hydrolytic Dechlorination

<div>Biodegradation of the highly persistent hexachlorocyclohexanes is difficult to assess in contaminated soils and sediments because this process occurs only slowly over timescales of years to decades. Recent instrumental advances for compound-specific isotope analysis (CSIA) now make it possible to monitor such processes based on the isotope fractionation of multiple elements as changes of 13C/12C, 37Cl/35Cl, and 2H/1H ratios in the residual HCH contamination. However, metabolic constraints from the expression of enzymes that can compete with the primary metabolic reactions leading to HCH biodegradation and thus alter the observable contaminant isotope fractionation through co metabolic side reactions have largely been overlooked. Here, we developed activity-based assays to assess the competitive behaviour of mixtures of lindane dehydrochlorinase LinA and haloalkane dehydrochlorinase LinB which catalyze the dehydrochlorination and hydrolytic dechlorination of several HCH isomers. Using X-HCH as model contaminant that can be transformed by both enzymes in mixtures of different LinA2/LinB activity, we observed preferential formation of products from hydrolytic dechlorination. This observation suggests that LinB was more reactive than predicted from the nominal enzyme activities. The C and H isotope fractionation of X-HCH in LinA2/LinB mixtures can be rationalized by a combination of isotope enrichment factors from independent dehydrochlorination and hydrolytic dechlorination reactions where LinA2 contributed more to H isotope fractionation than LinB, thus contrasting the assessment of competitive enzyme activity. Our study shows that metabolic constraints associated with the expression of multiple enzymes can potentially compromise inferences of extent and pathways of contaminant biodegradation from CSIA.</div>

scholarly journals Effect of Metabolic Constraints on the Observable Isotope Fractionation Associated with Aerobic Biodegradation of Hexachlorocyclohexanes

2019 ◽  
Author(s):  
Iris E. Schilling ◽  
Hans-Peter E. Kohler ◽  
Thomas Hofstetter
Keyword(s):  
Contaminated Soils ◽  
Isotope Fractionation ◽  
Isotope Analysis ◽  
Enrichment Factors ◽  
Aerobic Biodegradation ◽  
Side Reactions ◽  
Preferential Formation ◽  
Soils And Sediments ◽  
Competitive Behaviour ◽  
Hydrolytic Dechlorination

<div>Biodegradation of the highly persistent hexachlorocyclohexanes is difficult to assess in contaminated soils and sediments because this process occurs only slowly over timescales of years to decades. Recent instrumental advances for compound-specific isotope analysis (CSIA) now make it possible to monitor such processes based on the isotope fractionation of multiple elements as changes of 13C/12C, 37Cl/35Cl, and 2H/1H ratios in the residual HCH contamination. However, metabolic constraints from the expression of enzymes that can compete with the primary metabolic reactions leading to HCH biodegradation and thus alter the observable contaminant isotope fractionation through co metabolic side reactions have largely been overlooked. Here, we developed activity-based assays to assess the competitive behaviour of mixtures of lindane dehydrochlorinase LinA and haloalkane dehydrochlorinase LinB which catalyze the dehydrochlorination and hydrolytic dechlorination of several HCH isomers. Using X-HCH as model contaminant that can be transformed by both enzymes in mixtures of different LinA2/LinB activity, we observed preferential formation of products from hydrolytic dechlorination. This observation suggests that LinB was more reactive than predicted from the nominal enzyme activities. The C and H isotope fractionation of X-HCH in LinA2/LinB mixtures can be rationalized by a combination of isotope enrichment factors from independent dehydrochlorination and hydrolytic dechlorination reactions where LinA2 contributed more to H isotope fractionation than LinB, thus contrasting the assessment of competitive enzyme activity. Our study shows that metabolic constraints associated with the expression of multiple enzymes can potentially compromise inferences of extent and pathways of contaminant biodegradation from CSIA.</div>

Novel method for calculating two-dimensional blade vortex interaction

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 909-912
Author(s):  
Ronald J. Epstein ◽  
John A. Rule ◽  
Donald B. Bliss
Keyword(s):  
Two Dimensional ◽  
Vortex Interaction ◽  
Blade Vortex Interaction ◽  
Novel Method

scholarly journals Homogeneous 2D and 3D alignment of cardiomyocyte in dilated cardiomyopathy revealed by intravital heart imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kiyoshi Masuyama ◽  
Tomoaki Higo ◽  
Jong-Kook Lee ◽  
Ryohei Matsuura ◽  
Ian Jones ◽  
...  
Keyword(s):  
Heart Failure ◽  
Dilated Cardiomyopathy ◽  
Cardiac Dysfunction ◽  
Three Dimensional ◽  
Single Layer ◽  
Specific Pattern ◽  
Two Dimensional ◽  
Heart Imaging ◽  
Novel Method ◽  
2D And 3D

AbstractIn contrast to hypertrophic cardiomyopathy, there has been reported no specific pattern of cardiomyocyte array in dilated cardiomyopathy (DCM), partially because lack of alignment assessment in a three-dimensional (3D) manner. Here we have established a novel method to evaluate cardiomyocyte alignment in 3D using intravital heart imaging and demonstrated homogeneous alignment in DCM mice. Whilst cardiomyocytes of control mice changed their alignment by every layer in 3D and position twistedly even in a single layer, termed myocyte twist, cardiomyocytes of DCM mice aligned homogeneously both in two-dimensional (2D) and in 3D and lost myocyte twist. Manipulation of cultured cardiomyocyte toward homogeneously aligned increased their contractility, suggesting that homogeneous alignment in DCM mice is due to a sort of alignment remodelling as a way to compensate cardiac dysfunction. Our findings provide the first intravital evidence of cardiomyocyte alignment and will bring new insights into understanding the mechanism of heart failure.

A novel method to fabricate two-dimensional nanomaterial based on electrospinning

2021 ◽  
Vol 143 ◽  
pp. 106275
Author(s):  
Wenjing Ji ◽  
Guojie Zhao ◽  
Cong Guo ◽  
Li Fan ◽  
Hua Deng ◽  
...  
Keyword(s):  
Two Dimensional ◽  
Novel Method

scholarly journals Prediction of Wide Range Two-Dimensional Refractivity Using an IDW Interpolation Method from High-Altitude Refractivity Data of Multiple Meteorological Observatories

2021 ◽  
Vol 11 (4) ◽  
pp. 1431
Author(s):  
Sungsik Wang ◽  
Tae Heung Lim ◽  
Kyoungsoo Oh ◽  
Chulhun Seo ◽  
Hosung Choo
Keyword(s):  
High Altitude ◽  
Korean Peninsula ◽  
Interpolation Method ◽  
Atmospheric Condition ◽  
Propagation Path ◽  
Two Dimensional ◽  
Data Set ◽  
Wide Range ◽  
Atmospheric Data ◽  
Terrain Surface

This article proposes a method for the prediction of wide range two-dimensional refractivity for synthetic aperture radar (SAR) applications, using an inverse distance weighted (IDW) interpolation of high-altitude radio refractivity data from multiple meteorological observatories. The radio refractivity is extracted from an atmospheric data set of twenty meteorological observatories around the Korean Peninsula along a given altitude. Then, from the sparse refractive data, the two-dimensional regional radio refractivity of the entire Korean Peninsula is derived using the IDW interpolation, in consideration of the curvature of the Earth. The refractivities of the four seasons in 2019 are derived at the locations of seven meteorological observatories within the Korean Peninsula, using the refractivity data from the other nineteen observatories. The atmospheric refractivities on 15 February 2019 are then evaluated across the entire Korean Peninsula, using the atmospheric data collected from the twenty meteorological observatories. We found that the proposed IDW interpolation has the lowest average, the lowest average root-mean-square error (RMSE) of ∇M (gradient of M), and more continuous results than other methods. To compare the resulting IDW refractivity interpolation for airborne SAR applications, all the propagation path losses across Pohang and Heuksando are obtained using the standard atmospheric condition of ∇M = 118 and the observation-based interpolated atmospheric conditions on 15 February 2019. On the terrain surface ranging from 90 km to 190 km, the average path losses in the standard and derived conditions are 179.7 dB and 182.1 dB, respectively. Finally, based on the air-to-ground scenario in the SAR application, two-dimensional illuminated field intensities on the terrain surface are illustrated.

A Constrained Delaunay Triangulation Algorithm Based on Incremental Points

2011 ◽  
Vol 90-93 ◽  
pp. 3277-3282 ◽  
Author(s):  
Bai Chao Wu ◽  
Ai Ping Tang ◽  
Lian Fa Wang
Keyword(s):  
Information System ◽  
Data Structures ◽  
Delaunay Triangulation ◽  
Spanning Tree ◽  
Minimum Spanning Tree ◽  
Three Dimensional ◽  
Geographical Information ◽  
Two Dimensional ◽  
Data Set ◽  
Constrained Delaunay Triangulation

The foundation ofdelaunay triangulationandconstrained delaunay triangulationis the basis of three dimensional geographical information system which is one of hot issues of the contemporary era; moreover it is widely applied in finite element methods, terrain modeling and object reconstruction, euclidean minimum spanning tree and other applications. An algorithm for generatingconstrained delaunay triangulationin two dimensional planes is presented. The algorithm permits constrained edges and polygons (possibly with holes) to be specified in the triangulations, and describes some data structures related to constrained edges and polygons. In order to maintain the delaunay criterion largely，some new incremental points are added onto the constrained ones. After the data set is preprocessed, the foundation ofconstrained delaunay triangulationis showed as follows: firstly, the constrained edges and polygons generate initial triangulations，then the remained points completes the triangulation . Some pseudo-codes involved in the algorithm are provided. Finally, some conclusions and further studies are given.

scholarly journals Pedestrian detection algorithm in traffic scene based on weakly supervised hierarchical deep model

2016 ◽  
Vol 14 (1) ◽  
pp. 172988141769231 ◽  
Author(s):  
Yingfeng Cai ◽  
Youguo He ◽  
Hai Wang ◽  
Xiaoqiang Sun ◽  
Long Chen ◽  
...  
Keyword(s):  
Deep Learning ◽  
Pedestrian Detection ◽  
Recognition Rate ◽  
Detection Algorithm ◽  
Training Methods ◽  
Two Dimensional ◽  
Data Set ◽  
Deep Model ◽  
Unsupervised Training ◽  
Weakly Supervised

The emergence and development of deep learning theory in machine learning field provide new method for visual-based pedestrian recognition technology. To achieve better performance in this application, an improved weakly supervised hierarchical deep learning pedestrian recognition algorithm with two-dimensional deep belief networks is proposed. The improvements are made by taking into consideration the weaknesses of structure and training methods of existing classifiers. First, traditional one-dimensional deep belief network is expanded to two-dimensional that allows image matrix to be loaded directly to preserve more information of a sample space. Then, a determination regularization term with small weight is added to the traditional unsupervised training objective function. By this modification, original unsupervised training is transformed to weakly supervised training. Subsequently, that gives the extracted features discrimination ability. Multiple sets of comparative experiments show that the performance of the proposed algorithm is better than other deep learning algorithms in recognition rate and outperforms most of the existing state-of-the-art methods in non-occlusion pedestrian data set while performs fair in weakly and heavily occlusion data set.

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