scholarly journals Proton-Enhanced Dielectric Properties of Polyoxometalates in Water under Radio-Frequency Electromagnetic Waves

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1202 ◽  
Author(s):  
Shuntaro Tsubaki ◽  
Shogo Hayakawa ◽  
Tadaharu Ueda ◽  
Tomohiko Mitani ◽  
Ei-ichi Suzuki ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Radio Frequency ◽  
Electromagnetic Waves ◽  
Ionic Conduction ◽  
Silicotungstic Acid ◽  
High Loss ◽  
Grotthuss Mechanism ◽  
Proton Relay ◽  
Organic Solutions ◽  
Loss Factors

Electromagnetic waves, such as microwaves, have been used to enhance various chemical reactions over polyoxometalates. The dielectric properties of catalysts are among the relevant parameters facilitating catalytic reactions under electromagnetic radiation. This study describes the dielectric properties of polyoxometalate catalysts in aqueous and organic solutions to understand the mechanism of interactions between polyoxometalates and electromagnetic waves. Specific loss factors of polyoxometalates were observed at lower frequencies (<1 GHz) by the ionic conduction of the polyoxometalate solution. The evolution of ionic conduction depended strongly on cations rather than anions. Proton-type polyoxometalates exhibited significantly higher loss factors than other cations did. The activation energy for ionic conduction in protonated silicotungstic acid (H4SiW12O40) was significantly low in water (7.6–14.1 kJ/mol); therefore, the high loss factor of protonated polyoxometalates in water was attributed to the proton relay mechanism (i.e., Grotthuss mechanism). The results suggested that the proton relay mechanism at the radio-frequency band is critical for generating selective interactions of polyoxometalates with applied electromagnetic fields.

scholarly journals Dielectric Properties of Switchgrass and Corn Stover in the Radio Frequency Range

2021 ◽  
Vol 64 (1) ◽  
pp. 243-252
Author(s):  
Augusto M. Souza ◽  
Stuart J. Birrell ◽  
Brian L. Steward
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Moisture Content ◽  
Radio Frequency ◽  
Corn Stover ◽  
Loss Factor ◽  
Prediction Models ◽  
Dielectric Constants ◽  
Frequency Range ◽  
Loss Factors

HighlightsDielectric permittivities of switchgrass and corn stover in the radio frequency range were calculated.Prediction models achieved R2 &gt; 0.9, except for the switchgrass loss factor for the material in motion.The loss factors were different when static and in motion, but the dielectric constants were similar.Abstract. The dielectric properties of biological materials are relevant when developing moisture content sensors. However, little is known about the permittivities of switchgrass and corn stover in a wider frequency range. The goal of this research was to determine their dielectric constants and loss factors at different moisture contents across a frequency range of 5 Hz to 13 MHz and with the material static and in motion inside a sample container. The permittivity of these materials was calculated by measuring their admittance in a test fixture using an impedance analyzer at three different moisture levels (9.0% to 30.5%). Overall, the materials’ dielectric properties increased with moisture but decreased with frequency. Prediction models were developed using the data in a frequency range of 10 kHz to 5 MHz. Model coefficients of determination were higher than 0.90 in general, except for the model measuring the loss factor of switchgrass in motion. Additionally, the dielectric constant was not different with the materials static or in motion, but the loss factor values were distinct. This work can be used for the development of electrical moisture content sensors for switchgrass and corn stover. Keywords: Corn stover, Dielectric constant, Loss factor, Moisture content, Permittivity, Switchgrass.

Destruction of water-in-oil emulsions in electromagnetic fields in a dynamic mode

2012 ◽  
Vol 9 (1) ◽  
pp. 110-115
Author(s):  
L.A. Kovaleva ◽  
R.R. Zinnatullin ◽  
V.N. Blagochinnov ◽  
A.A. Musin ◽  
Yu.I. Fatkhullina ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Radio Frequency ◽  
Electromagnetic Fields ◽  
Dynamic Mode ◽  
Droplet Dynamics ◽  
Oil Emulsion ◽  
Numerical Studies ◽  
Em Field ◽  
Oil Emulsions ◽  
Water In Oil Emulsion

Some results of experimental and numerical studies of the influence of radio-frequency (RF) and microwave (MW) electromagnetic (EM) fields on water-in-oil emulsions are presented. A detailed investigation of the dependence of the dielectric properties of emulsions on the frequency of the field makes it possible to establish the most effective frequency range of the EM influence. The results of water-in-oil emulsion stability in the RF EM field depending on their dielectric properties are presented. The effect of the MW EM field on the emulsion in a dynamic mode has been studied experimentally. In an attempt to understand the mechanism of emulsion destruction the mathematical model for a single emulsion droplet dynamics in radio-frequency (RF) and microwave (MW) electromagnetic fields is formulated.

Potential Impact of RFID-Based Tracing Systems on the Integrity of Pharmaceutical Products

2012 ◽  
pp. 1724-1745
Author(s):  
Michele Maffia ◽  
Luca Mainetti ◽  
Luigi Patrono ◽  
Emanuela Urso
Keyword(s):  
Supply Chain ◽  
Radio Frequency ◽  
Radio Frequency Identification ◽  
Electromagnetic Waves ◽  
Peptide Hormone ◽  
Pharmaceutical Products ◽  
Pharmaceutical Supply Chain ◽  
Rf Devices ◽  
And Performance ◽  
Auto Identification

Radio Frequency Identification (RFID) is going to play a crucial role as auto-identification technology in a wide range of applications such as healthcare, logistics, supply chain management, ticketing, et cetera. The use of electromagnetic waves to identify, trace, and track people or goods allows solving many problems related to auto-identification devices based on optical reading (i.e. bar code). Currently, high interest is concentrated on the use of Radio Frequency (RF) solutions in healthcare and pharmaceutical supply chain, in order to improve drugs flow transparency and patients’ safety. Unfortunately, there is a possibility that drug interaction with electromagnetic fields (EMFs) generated by RF devices, such as RFID readers, deteriorate the potency of bioactive compounds. This chapter proposes an experimental multidisciplinary approach to investigate potential alterations induced by EMFs on drug molecular structure and performance. To show the versatility of this approach, some experimental results obtained on two biological pharmaceuticals (peptide hormone-based) are discussed.

Dielectric properties, heating rate, and heating uniformity of various seasoning spices and their mixtures with radio frequency heating

2018 ◽  
Vol 228 ◽  
pp. 128-141 ◽  
Author(s):  
Samet Ozturk ◽  
Fanbin Kong ◽  
Rakesh K. Singh ◽  
Jesse Daniel Kuzy ◽  
Changying Li ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Radio Frequency ◽  
Heating Rate ◽  
Radio Frequency Heating ◽  
Heating Uniformity ◽  
Frequency Heating
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