Measurement of trace metal influx in plants: a case study with Co

2004 ◽  
Vol 31 (9) ◽  
pp. 941 ◽  
Author(s):  
Rob Reid ◽  
Juhong Liu
Keyword(s):  
Trace Metals ◽  
Trace Metal ◽  
Membrane Surface ◽  
Transport Systems ◽  
Ph Effects ◽  
Flux Measurements ◽  
Membrane Surface Charge ◽  
Broad Specificity

The analysis of transport systems involved in the uptake of trace metals in plants is complicated by technical difficulties associated with measurement of uptake and by the likely presence of multiple transporters with broad specificity. In this study, influx of Co was used to illustrate the problems involved and potential solutions. Issues surrounding kinetic descriptions of transport, multiple uptake systems, specificity of transporters, pH effects and the role of membrane surface charge in determining fluxes are addressed. A list of criteria for validation of flux measurements is provided.

scholarly journals To close or to collapse: the role of charges on membrane stability upon pore formation

2020 ◽  
Author(s):  
Rafael B. Lira ◽  
Fernanda S.C. Leomil ◽  
Renan J. Melo ◽  
Karin A. Riske ◽  
Rumiana Dimova
Keyword(s):  
Pore Formation ◽  
Electric Pulse ◽  
Membrane Surface ◽  
Medium Composition ◽  
Membrane Stability ◽  
Giant Vesicles ◽  
Membrane Pores ◽  
Edge Tension ◽  
Membrane Surface Charge

AbstractResealing of membrane pores is crucial for cell survival. We study membrane surface charge and medium composition as defining regulators of membrane stability. Pores are generated by electric field or detergents. Giant vesicles composed of zwitterionic and negatively charged lipids mixed at varying ratios are subjected to a single strong electric pulse. Charged vesicles are prone to catastrophic collapse transforming them into tubular structures. The spectrum of destabilization responses includes the generation of long-living submicroscopic pores and partial vesicle bursting. The origin of these phenomena is related to the membrane edge tension, which governs pore closure. This edge tension significantly decreases as a function of the fraction of charged lipids. Destabilization of charged vesicles upon pore formation is universal – it is also observed with other poration stimuli. Disruption propensity is enhanced for membranes made of lipids with higher degree of unsaturation. It can be reversed by screening membrane charge in the presence of calcium ions. We interpret the observed findings in light of theories of stability and curvature generation and discuss mechanisms acting in cells to prevent total membrane collapse upon poration. Enhanced membrane stability is crucial for the success of electroporation-based technologies for cancer treatment and gene transfer.

scholarly journals Impact of fear of crimes on public transport usage: A case study of Delhi

2020 ◽  
Vol 66 (3) ◽  
pp. 247-258
Author(s):  
Rabindra Nath Dubey ◽  
Keyword(s):  
Public Transport ◽  
Transport Systems ◽  
Public Transport System ◽  
Weak Negative Correlation ◽  
Bus Service ◽  
Bus Services ◽  
The City ◽  
Spearman’S Correlation

Delhi Transport Corporation (DTC and Delhi Metro-Rail System (DMRS) are two important public transport systems in Delhi. The DMRS has been attractive in respect to ridership but in 2015 it has shown a decrease in its ridership. It has also been found that ridership of the bus service, the most important public transport system for the poor in Delhi, has decreased over time whereas the numbers of private vehicles have recorded phenomenal increase resulting in traffic congestions and pollution problems in the city. The purpose of this study is to explore the role of the fear of crimes along with other reasons for decreasing trends in the usage of public transport in Delhi. The study is based on people opinion and perception for which 350 persons were interviewed with the structured questionnaire from ten transit places having varied socio-economic conditions. Fear of crimes within buses/coaches is considered an important reason for not using public transport in western countries but as per this study, the same is not true in the case of Delhi. Role of fear of crimes along with other factors was verified with the spearman’s correlation coefficient. The weak negative correlation has been found between the preference to public bus services and the fear of crimes; the crowing; the unavailability. It indicates that along with these other factors are equally responsible for the choice of public transports in Delhi.

Towards Simulating Cognitive Agents in Public Transport Systems

2009 ◽  
pp. 176-191 ◽  
Author(s):  
Sabine Timpf
Keyword(s):  
Public Transport ◽  
Spatial Models ◽  
Transport Systems ◽  
Default Reasoning ◽  
Cognitive Agents ◽  
Human Navigation ◽  
The World ◽  
Spatial Environment

In this chapter, the authors present a methodology for simulating human navigation within the context of public, multi-modal transport. They show that cognitive agents, that is, agents that can reason about the navigation process and learn from and navigate through the (simulated physical) environment, require the provision of a rich spatial environment. From a cognitive standpoint, human navigation and wayfinding rely on a combination of spatial models (“knowledge in the head”), (default) reasoning processes, and knowledge in the world. Spatial models have been studied extensively, whereas the reasoning processes and especially the role of the “knowledge in the world” have been neglected. The authors first present an overview of research in wayfinding and then envision a model that integrates existing concepts and models for multi-modal public transport illustrated by a case study.

A case study investigating the effects of EDTA washing and amendments on trace metal-contaminated soil

2020 ◽  
Author(s):  
Wolfgang Friesl-Hanl ◽  
Christoph Sebastian Noller ◽  
Rebecca Hood-Nowotny ◽  
Andrea Watzinger
Keyword(s):  
Trace Metals ◽  
Trace Metal ◽  
Soil Washing ◽  
Ex Situ ◽  
Metal Extraction ◽  
Garden Soil ◽  
Soil Conditions ◽  
Industrial Emissions ◽  
Guideline Values

<p>Trace metals emissions show a sustaining decrease in western Europe since several decades. Sources like leaded fuels have been banned and the use of efficient flue gas cleaning systems have reduced industrial emissions significantly. But trace metal additions are cumulative, and the contamination is permanent. Immobilizing trace metals can be an efficient and cost effective way to prevent groundwater contamination and uptake in the food chain but cannot account for all exposure pathways (e.g. ingestion), while guideline values are only concerned about total concentrations. Soil washing techniques comprise an enormous potential for the efficient and sustainable extraction of trace metals from contaminated soils. The Garden Soil Project is a case study investigating the effect of soil amendments applied after a new ex-situ soil washing procedure (Ethylenediaminetetraacetic acid) from a Cd-, Pb-, Zn-contaminated Cambisol from Arnoldstein, located at a former lead mining and smelting region in Austria.</p><p>To investigate the success of the EDTA soil washing and amendment application, an experimental garden was set up at the University Research Center (UFT) in Tulln an der Donau. It encompasses twelve raised beds of 1 m<sup>3</sup>, filled with three soil variants in four replicates: The contaminated, unwashed soil (U) and two washed variants (W), one amended with 2 %wt biochar and 2 %wt compost (A). The amendments aim to restore soil conditions after the invasive procedure. The success of the trace metal extraction and restoration of the original soil properties is investigated by analyzing vegetable cultivars grown on the soil variants, the physicochemical and microbiological characteristics of the soil in the course of 2 years. First results show a significant reduction in trace metal uptake by different vegetables after washing and an increase in biomass for both washed soil variants W and A. The continuing analysis of trace metals in soil leachates and multiple extractable fractions in soil will allow a more detailed assessment. Furthermore, an ongoing investigation of the carbon and nitrogen cycle, using stable isotopes, will be applied as an indicator for soil functions.</p>

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