A novel mechanistic anion exclusion model to investigate partially water‐saturated transport in soils and shales: a case study of nitrate solution flow

2021 ◽  
Author(s):  
Nima Hamidian Shoormasti ◽  
Seyyed Alireza Tabatabaei‐Nezhad
Keyword(s):  
Nitrate Solution ◽  
Solution Flow ◽  
Anion Exclusion ◽  
Water Saturated

Electrostatic charge interaction: a case study on tapered PMMA fiber for calcium nitrate detection

Sensor Review ◽  
2014 ◽  
Vol 34 (4) ◽  
pp. 424-427 ◽  
Author(s):  
M. Batumalay ◽  
A. Lokman ◽  
H.A. Rahman ◽  
S.W. Harun ◽  
H. Ahmad
Keyword(s):  
Limit Of Detection ◽  
Nitrate Solution ◽  
Calcium Nitrate ◽  
Fiber Optic Sensor ◽  
Multimode Fiber ◽  
Working Mechanism ◽  
Content Type ◽  
Charge Interaction ◽  
Chemical Solutions

Purpose – This paper aims to propose and demonstrate a simple fiber optic sensor using a tapered plastic multimode fiber as a probe for measurement of calcium nitrate concentrations in de-ionized water. Design/methodology/approach – The working mechanism is based on the observed increment in the transmission of the sensor that is immersed in calcium nitrate solution of higher concentration. The tapering of the plastic fiber is carried out by etching method using acetone, sand paper and de-ionized water. Findings – Tapered fiber with diameter 0.45 mm gives the highest sensitivity of 0.028 mV/% due to better interaction between the evanescent field and the calcium nitrate solution with a good slope linearity of more than 98 per cent for a 1.07 per cent limit of detection in a straight probe arrangement. The use of calcium and nitrate ions within the sensing medium demonstrates the strong dependency of the sensor output trend on the electrolytic nature of the chemical solutions. Originality/value – Demonstration of tapered plastic multimode fiber sensor probe for measurement electrolytic chemical solutions.

scholarly journals BENTONITE-QUARTZ SAND AS THE BACKFILL MATERIALS ON THE RADIOACTIVE WASTE REPOSITORY

2010 ◽  
Vol 5 (2) ◽  
pp. 115-120
Author(s):  
Raharjo Raharjo
Keyword(s):  
Radioactive Waste ◽  
Quartz Sand ◽  
Nitrate Solution ◽  
Fixed Bed ◽  
Weight Percent ◽  
Retardation Factor ◽  
Backfill Materials ◽  
Uranium Migration ◽  
Water Saturated ◽  
Bentonite Particle

An investigation of the contribution of quartz sand in the bentonite mixture as the backfill materials on the shallow land burial of radioactive waste has been done. The experiment objective is to determine the effect of quartz sand in a bentonite mixture with bentonite particle sizes of -20+40, -40+60, and -60+80 mesh on the retardation factor and the uranium dispersion in the simulation of uranium migration in the backfill materials. The experiment was carried out by the fixed bed method in the column filled by the bentonite mixture with a bentonite-to-quartz sand weight percent ratio of 0/100, 25/75, 50/50, 75/25, and 100/0 on the water saturated condition flown by uranyl nitrate solution at concentration (Co) of 500 ppm. The concentration of uranium in the effluents in interval 15 minutes represented as Ct was analyzed by spectrophotometer, then using Co and Ct, retardation factor (R) and dispersivity () were determined. The experiment data showed that the bentonite of -60+80 mesh and the quartz sand of -20+40 mesh on bentonite-to-quartz sand with weight percent ratio of 50/50 gave the highest retardation factor and dispersivity of 18.37 and 0.0363 cm, respectively.   Keywords: bentonite, quartz sand, backfill materials, radioactive waste  

Seismic study of the low-permeability volume in southern France karst systems

Geophysics ◽  
2014 ◽  
Vol 79 (1) ◽  
pp. EN1-EN13 ◽  
Author(s):  
Pierre-Yves Galibert ◽  
Rémi Valois ◽  
Manuela Mendes ◽  
Roger Guérin
Keyword(s):  
Seismic Attenuation ◽  
Low Permeability ◽  
Driving Mechanism ◽  
Refraction Tomography ◽  
Seismic Amplitudes ◽  
Karst Systems ◽  
Water Saturated ◽  
Low Amplitude ◽  
Wave Induced

Locating groundwater in deep-seated karst aquifers is inherently difficult. With seismic methods, we studied the upper epikarst and the underneath low-permeability volume (LPV) of several karst systems located in the southern Quercy and Larzac regions of France and found that refraction tomography was effective only in the epikarst and not in the LPV. We evaluated a 3D case study using a combination of surface records and downhole receivers to overcome this limitation. This 3D approach unveiled a set of elongated furrows at the base of the epikarst and identified heterogeneities deep inside the LPV that may represent high-permeability preferred pathways for water inside the karst. To achieve the same result when no borehole was available, we studied seismic amplitudes of the wavefield, recognizing that wave-induced fluid flow in low-permeability carbonates is a driving mechanism of seismic attenuation. We developed a workflow describing the heterogeneity of the LPV with spectral attributes derived from surface-consistent decomposition principles, and we validated its effectiveness at benchmark locations. We applied this workflow to the 3D study and found a low-amplitude signal area at depth; we interpreted this anomaly as a water-saturated body perched above the aquifer.

Cs batch sorption and column transport experiments on sand from the Yamin plain, Israel – Experimental results and modelling

2020 ◽  
Author(s):  
Ofra Klein-BenDavid ◽  
Noa Balaban ◽  
Svetlana Gelfer ◽  
Ronen Komerian ◽  
David Saban ◽  
...  
Keyword(s):  
Doping Level ◽  
Nitrate Solution ◽  
Solution Chemistry ◽  
Radioactive Waste Disposal ◽  
Disposal Site ◽  
Solution Flow ◽  
Batch Sorption ◽  
Conservative Tracer ◽  
Kd Values ◽  
Concentrated Solution

<p>The Yanim plain hosts the national Israeli radioactive waste disposal site. The site is located on the Miocene aged Hazeva formation, comprised of loose sand, sandstone and dispersed clay layers. The current research examines the sorption capacity of the local sand to solutions doped with Cs ions. The sand contains ~95% quartz and ~5% of various clays, carbonates, and oxides. Batch sorption experiments were conducted at a liquid to solid ratio of 10. Two end-member solutions were used, fresh (MQ) and concentrated (Na-Nitrate solution). Both solutions were doped with 0.1, 1, 10, 100 and 1000 ppm of Cs (as a nitrate). For the MQ experiments Kd values ranged between ~2 and ~1300, where the highest Kds were registered for the 1 ppm doping level, and the smallest Kds were for the 1000 ppm doping level. For the concentrated solution Kd values ranged between ~0 and ~1.5, where the highest Kds were for the 1 ppm doping level, for all other doping levels Kds were <1. Freundlich and Langmuir isotherm calculations revealed a significantly better correlation on a linearized Freundlich isotherm, indicating a multi-layer and multi-site sorption model, with a similar slope for both solutions, indicating a common sorption mechanism. Column transport experiments (L=25cm, r=2cm, φ=30%, 1PV=180cc) have shown minimal retardation of the Cs in the concentrated solution flow experiments (R= ~2). A second, probably colloid-related peak, showed an early breakthrough with respect to a conservative color tracer.  On the other hand, when MQ was run in the column no breakthrough was observed within 10 column pore volumes. In one fresh experiment a very small colloid related peak was found with breakthrough similar to the conservative tracer. We used the CXTFIT model to calculated the dispersity (λ [L]) and normalized velocity (V) of the measured tracer. For the conservative tracer the values were λ=0.13 cm and V=0.9 cm. For Cs transport in the concentrated solution λ=0.22 cm and V=1.6. Thus, it may be concluded that even in similar doping levels in the same matrix the solution chemistry will play a major role in contaminant retardation. Thus, rain episodes which abruptly change the solution chemistry, can significantly affect solute and colloid mobility.</p>

The Genesis and Internal Dynamics of El Salvador's People's Revolutionary Army, 1970–1976

2014 ◽  
Vol 38 (01) ◽  
pp. 102-129
Author(s):  
ALBERTO MARTÍN ÁLVAREZ ◽  
EUDALD CORTINA ORERO
Keyword(s):  
Latin America ◽  
El Salvador ◽  
Early Years ◽  
Left Wing ◽  
Internal Dynamics ◽  
Internal Coherence ◽  
The 1960S

AbstractUsing interviews with former militants and previously unpublished documents, this article traces the genesis and internal dynamics of the Ejército Revolucionario del Pueblo (People's Revolutionary Army, ERP) in El Salvador during the early years of its existence (1970–6). This period was marked by the inability of the ERP to maintain internal coherence or any consensus on revolutionary strategy, which led to a series of splits and internal fights over control of the organisation. The evidence marshalled in this case study sheds new light on the origins of the armed Salvadorean Left and thus contributes to a wider understanding of the processes of formation and internal dynamics of armed left-wing groups that emerged from the 1960s onwards in Latin America.

Culture and the plasticity of perception

2020 ◽  
Vol 43 ◽  
Author(s):  
Michael Lifshitz ◽  
T. M. Luhrmann
Keyword(s):  
Cultural Context ◽  
Sensory Experience ◽  
Cultural Learning ◽  
The World

Abstract Culture shapes our basic sensory experience of the world. This is particularly striking in the study of religion and psychosis, where we and others have shown that cultural context determines both the structure and content of hallucination-like events. The cultural shaping of hallucinations may provide a rich case-study for linking cultural learning with emerging prediction-based models of perception.

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

Sociocultural memory development research drives new directions in gadgetry science

2019 ◽  
Vol 42 ◽  
Author(s):  
Penny Van Bergen ◽  
John Sutton
Keyword(s):  
Episodic Memory ◽  
Autobiographical Memory ◽  
Developmental Psychology ◽  
Cross Cultural ◽  
Memory Development ◽  
Development Research ◽  
Cultural Research ◽  
New Directions ◽  
Cross Cultural Research

Abstract Sociocultural developmental psychology can drive new directions in gadgetry science. We use autobiographical memory, a compound capacity incorporating episodic memory, as a case study. Autobiographical memory emerges late in development, supported by interactions with parents. Intervention research highlights the causal influence of these interactions, whereas cross-cultural research demonstrates culturally determined diversity. Different patterns of inheritance are discussed.

An Environmental Wet Cell For High Voltage Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 18-19
Author(s):  
N.J. Tighe ◽  
H.M. Flower ◽  
P.R. Swann
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Image Quality ◽  
Inelastic Scattering ◽  
High Voltage ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Environmental Cell ◽  
Water Saturated ◽  
High Temperature Gas

A differentially pumped environmental cell has been developed for use in the AEI EM7 million volt microscope. In the initial version the column of gas traversed by the beam was 5.5mm. This permited inclusion of a tilting hot stage in the cell for investigating high temperature gas-specimen reactions. In order to examine specimens in the wet state it was found that a pressure of approximately 400 torr of water saturated helium was needed around the specimen to prevent dehydration. Inelastic scattering by the water resulted in a sharp loss of image quality. Therefore a modified cell with an ‘airgap’ of only 1.5mm has been constructed. The shorter electron path through the gas permits examination of specimens at the necessary pressure of moist helium; the specimen can still be tilted about the side entry rod axis by ±7°C to obtain stereopairs.

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