scholarly journals Highly Multifunctional GNP/Epoxy Nanocomposites: From Strain-Sensing to Joule Heating Applications

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2431
Author(s):  
Xoan F. Sánchez-Romate ◽  
Alejandro Sans ◽  
Alberto Jiménez-Suárez ◽  
Mónica Campo ◽  
Alejandro Ureña ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Joule Heating ◽  
Dominant Role ◽  
Strain Sensors ◽  
Sonication Time ◽  
Strain Sensing ◽  
Strain Monitoring ◽  
Radar Chart ◽  
Nanofiller Content

A performance mapping of GNP/epoxy composites was developed according to their electromechanical and electrothermal properties for applications as strain sensors and Joule heaters. To achieve this purpose, a deep theoretical and experimental study of the thermal and electrical conductivity of nanocomposites has been carried out, determining the influence of both nanofiller content and sonication time. Concerning dispersion procedure, at lower contents, higher sonication times induce a decrease of thermal and electrical conductivity due to a more prevalent GNP breakage effect. However, at higher GNP contents, sonication time implies an enhancement of both electrical and thermal properties due to a prevalence of exfoliating mechanisms. Strain monitoring tests indicate that electrical sensitivity increases in an opposite way than electrical conductivity, due to a higher prevalence of tunneling mechanisms, with the 5 wt.% specimens being those with the best results. Moreover, Joule heating tests showed the dominant role of electrical mechanisms on the effectiveness of resistive heating, with the 8 wt.% GNP samples being those with the best capabilities. By taking the different functionalities into account, it can be concluded that 5 wt.% samples with 1 h sonication time are the most balanced for electrothermal applications, as shown in a radar chart.

scholarly journals Electrical Properties and Strain Sensing Mechanisms in Hybrid Graphene Nanoplatelet/Carbon Nanotube Nanocomposites

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5530
Author(s):  
Xoan F. Sánchez-Romate ◽  
Alberto Jiménez-Suárez ◽  
Mónica Campo ◽  
Alejandro Ureña ◽  
Silvia G. Prolongo
Keyword(s):  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Transport Mechanisms ◽  
Sonication Time ◽  
Strain Sensing ◽  
Electromechanical Properties ◽  
Exponential Behavior ◽  
Graphene Nanoplatelet ◽  
Low Viscosity ◽  
Nanofiller Content

Electrical and electromechanical properties of hybrid graphene nanoplatelet (GNP)/carbon nanotube (CNT)-reinforced composites were analyzed under two different sonication conditions. The electrical conductivity increases with increasing nanofiller content, while the optimum sonication time decreases in a low viscosity media. Therefore, for samples with a higher concentration of GNPs, an increase of sonication time of the hybrid GNP/CNT mixture generally leads to an enhancement of the electrical conductivity, up to values of 3 S/m. This means that the optimum sonication process to achieve the best performances is reached in the longest times. Strain sensing tests show a higher prevalence of GNPs at samples with a high GNP/CNT ratio, reaching gauge factors of around 10, with an exponential behavior of electrical resistance with applied strain, whereas samples with lower GNP/CNT ratio have a more linear response owing to a higher prevalence of CNT tunneling transport mechanisms, with gauge factors of around 3–4.

Micromechanics Modeling of Bi-Axial Stretching Effects on the Electrical Conductivity of CNT-Polymer Composites

2015 ◽  
Vol 07 (01) ◽  
pp. 1550005 ◽  
Author(s):  
Chuang Feng ◽  
Liying Jiang
Keyword(s):  
Electrical Conductivity ◽  
Polymer Composites ◽  
Volume Expansion ◽  
Dominant Role ◽  
Separation Distance ◽  
Simulation Results ◽  
Axial Stretching ◽  
Micromechanics Modeling ◽  
Variation Trends

In this paper, the bi-axial stretching effects on the electrical conductivity of carbon nanotube (CNT)-polymer composites are studied by a mixed micromechanics model with the consideration of the electrical conductive mechanisms. The bi-axial stretching effects are characterized by volume expansion of composite, re-orientation of CNTs and change of conductive networks. Simulation results demonstrate that the bi-axial stretching decreases the electrical conductivity of the composites due to the dominant role of the stretching-induced change in conductive networks, i.e., the increase in the percolation threshold, the separation distance among CNTs and the breakdown of the networks. It is also found that the bi-axial stretching enhances the decreasing rate of the electrical conductivity and increases the distribution randomness of the CNTs in the bi-axial stretching plane, as compared to a uni-axial stretching case. Furthermore, the dependency of the variation of electrical conductivity on the CNT concentration and sizes is also investigated. Possible reasons for the variation trends are interpreted. The study in this paper is expected to provide an increased understanding on the stretching effects upon the electrical conductivity of CNT-polymer composites.

Electrical Conductivity and Structure of Nanocrystalline CeO2 Thin Films

1996 ◽  
Vol 453 ◽  
Author(s):  
Igor Kosacki ◽  
Harlan U. Anderson
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Dominant Role ◽  
Boundary Phase ◽  
Electrical Measurements

AbstractThe results of structural and electrical measurements of nanocrystalline CeO2 thin films are presented. A correlation between the electrical conductivity and microstructure has been observed and discussed. The electrical properties of nanocrystalline CeO2 thin films are attributed to a dominant role of grain boundary phase.

Chronic Pain: Fundamental Scientific Considerations, Specifically for Legal Claims

2013 ◽  
Vol 18 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Robert J. Barth
Keyword(s):  
Health Outcomes ◽  
Pain Perception ◽  
Driving Forces ◽  
Psychological Treatment ◽  
Dominant Role ◽  
Meta Analysis ◽  
General Medicine ◽  
Pain Syndrome ◽  
Problematic Relationship

Abstract Scientific findings have indicated that psychological and social factors are the driving forces behind most chronic benign pain presentations, especially in a claim context, and are relevant to at least three of the AMA Guides publications: AMA Guides to Evaluation of Disease and Injury Causation, AMA Guides to Work Ability and Return to Work, and AMA Guides to the Evaluation of Permanent Impairment. The author reviews and summarizes studies that have identified the dominant role of financial, psychological, and other non–general medicine factors in patients who report low back pain. For example, one meta-analysis found that compensation results in an increase in pain perception and a reduction in the ability to benefit from medical and psychological treatment. Other studies have found a correlation between the level of compensation and health outcomes (greater compensation is associated with worse outcomes), and legal systems that discourage compensation for pain produce better health outcomes. One study found that, among persons with carpal tunnel syndrome, claimants had worse outcomes than nonclaimants despite receiving more treatment; another examined the problematic relationship between complex regional pain syndrome (CRPS) and compensation and found that cases of CRPS are dominated by legal claims, a disparity that highlights the dominant role of compensation. Workers’ compensation claimants are almost never evaluated for personality disorders or mental illness. The article concludes with recommendations that evaluators can consider in individual cases.

ROLE OF ADDED PHOSPHOGYPSUM AND HUMIC ACIDS IN THE KINETIC RELEASE OF SALT FROM SALT AFFECTED SOIL (SALINE – SODIC)

2020 ◽  
pp. 15-27
Keyword(s):  
Electrical Conductivity ◽  
Humic Acids ◽  
Release Rate ◽  
Release Kinetics ◽  
Sodium Adsorption Ratio ◽  
Salt Affected Soil ◽  
Two Factors ◽  
Dissolved Ions ◽  
Kinetic Release

In order to study the effect of phosphogypsum and humic acids in the kinetic release of salt from salt-affected soil, a laboratory experiment was conducted in which columns made from solid polyethylene were 60.0 cm high and 7.1 cm in diameter. The columns were filled with soil so that the depth of the soil was 30 cm inside the column, the experiment included two factors, the first factor was phosphogypsum and was added at levels 0, 5, 10 and 15 tons ha-1 and the second-factor humic acids were added at levels 0, 50, 100 and 150 kg ha-1 by mixing them with the first 5 cm of column soil and one repeater per treatment. The continuous leaching method was used by using an electrolytic well water 2.72 dS m-1. Collect the leachate daily and continue the leaching process until the arrival of the electrical conductivity of the filtration of leaching up to 3-5 dS m-1. The electrical conductivity and the concentration of positive dissolved ions (Ca, Mg, Na) were estimated in leachate and the sodium adsorption ratio (SAR) was calculated. The results showed that the best equation for describing release kinetics of the salts and sodium adsorption ratio in soil over time is the diffusion equation. Increasing the level of addition of phosphogypsum and humic acids increased the constant release velocity (K) of salts and the sodium adsorption ratio. The interaction between phosphogypsum and humic acids was also affected by the constant release velocity of salts and the sodium adsorption ratio. The constant release velocity (K) of the salts and the sodium adsorption ratio at any level of addition of phosphogypsum increased with the addition of humic acids. The highest salts release rate was 216.57 in PG3HA3, while the lowest rate was 149.48 in PG0HA0. The highest release rate of sodium adsorption ratio was 206.09 in PG3HA3, while the lowest rate was 117.23 in PG0HA0.

НЕКОТОРЫЕ ОСОБЕННОСТИ РАСПРОСТРАНЕННОСТИ РЕСПИРАТОРНОЙ АЛЛЕРГИИ НА ЮГЕ РОССИИ

2019 ◽  
Author(s):  
D.Sh. Macharadze
Keyword(s):  
Dominant Role ◽  
Pollen Allergy ◽  
Respiratory Allergy ◽  
House Dust Mites ◽  
Dust Mites ◽  
The Past ◽  
Regional Features ◽  
Respiratory Allergies ◽  
Southern Russia

В обзорной статье приведены данные по распространенности респираторной аллергии - аллергического ринита и бронхиальной астмы на юге России, опубликованные за последние десятилетия. Показана доминирующая роль пыльцевой аллергии практически во всем южном регионе России. В Чеченской Республике у больных респираторной аллергией обнаружена сходная частота встречаемости сенсибилизации к клещам домашней пыли и пыльце злаковых трав (51,1 и 52,5 соответственно), тогда как сенсибилизация к пыльце амброзии и полыни встречалась в 3 раза реже (26,6 и 20,7 соответственно) по сравнению с соседними регионами юга России. Эти данные демонстрируют климатогеографические, экологические и другие региональные особенности в распространении респираторной аллергии.The review article presents data on the prevalence of respiratory allergy - allergic rhinitis and bronchial asthma in southern Russia, published over the past decades. The dominant role of pollen allergy is shown in almost the entire southern region of Russia. In the Chechen Republic, sensitization to house dust mites and grass pollen was found in patients with respiratory allergy equally (51.1 and 52.5, respectively), whereas ragweed and mugwort sensitization was 3 times less (26.6 and 20.7, respectively) compared with the neighboring regions of southern Russia. These data demonstrate climate-geographical, environmental and other regional features in the prevalence of respiratory allergies.

KEGAGALAN PRIVATISASI BUMN DI ERA REZIM ORDE BARU DALAM PERSPEKTIF EKONOMI POLITIK

Wacana Publik ◽  
2019 ◽  
Vol 12 (02) ◽  
Author(s):  
Syamsul Ma'arif
Keyword(s):  
Market Economy ◽  
Free Market ◽  
Dominant Role ◽  
The State ◽  
Early Years ◽  
New Order ◽  
Free Market Economy ◽  
Economic Sectors ◽  
Role Of The State

After had being carried out nationalization and hostility against west countries, the New Order regime made important decision to change Indonesia economic direction from etatism system to free market economy. A set of policies were taken in order private sector could play major role in economic. However, when another economic sectors were reformed substantially, effords to reform the State Owned Enterprises had failed. The State Owned Enterprise, in fact, remained to play dominant role like early years of guided democracy era. Role of the State Owned Enterprises was more and more powerfull). The main problem of reforms finally lied on reality that vested interest of bureaucrats (civil or military) was so large that could’nt been overcome. 

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