scholarly journals Impact of Conducting Polymer Filler on the Dielectric Properties of Nylon 11

2009 ◽  
Vol 3 (1) ◽  
pp. 47-51
Author(s):  
Shilpa Pande ◽  
◽  
Deepali Kelkar ◽  
Dilip Peshwe ◽  
◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Conducting Polymer ◽  
High Frequency ◽  
Filler Content ◽  
Dissipation Factor ◽  
Polymer Filler ◽  
Wide Range ◽  
Conducting Filler ◽  
Nylon 11

The dielectric studies of semi-crystalline Nylon 11 filled with a conducting polymer (PANI) were investigated in a wide range of frequency and temperature by using Impedance Analyzer. The main focus was on the effects of conducting filler content on dielectric properties of Nylon 11. The prominent factors such as dielectric permittivity, loss factor, and loss tangent were studied at high frequency. Two different concentrations (1 % and 5 % w/w) of the conducting filler were used. It was observed that with the increase of fillers concentration, the value of dielectric permittivity (ε’)б The dissipation factor (ε’’) and loss (tan ) decrease compared to pure Nylon 11.

scholarly journals Sintering, Microstructure, and Dielectric Properties of Copper Borates for High Frequency LTCC Applications

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4017
Author(s):  
Dorota Szwagierczak ◽  
Beata Synkiewicz-Musialska ◽  
Jan Kulawik ◽  
Norbert Pałka
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Terahertz Time Domain Spectroscopy ◽  
Very High Frequency ◽  
X Ray ◽  
Low Dielectric ◽  
Very High

New ceramic materials based on two copper borates, CuB2O4 and Cu3B2O6, were prepared via solid state synthesis and sintering, and characterized as promising candidates for low dielectric permittivity substrates for very high frequency circuits. The sintering behavior, composition, microstructure, and dielectric properties of the ceramics were investigated using a heating microscope, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, and terahertz time domain spectroscopy. The studies revealed a low dielectric permittivity of 5.1–6.7 and low dielectric loss in the frequency range 0.14–0.7 THz. The copper borate-based materials, owing to a low sintering temperature of 900–960 °C, are suitable for LTCC (low temperature cofired ceramics) applications.

scholarly journals Permittivity and Loss of Composites of Epoxy Resin and Kevlar Fibres

1995 ◽  
Vol 4 (4) ◽  
pp. 096369359500400 ◽  
Author(s):  
G.M. Tsangaris ◽  
G.C. Psarras
Keyword(s):  
Dielectric Permittivity ◽  
Epoxy Resin ◽  
Filler Content ◽  
Low Frequency ◽  
Interfacial Polarization ◽  
Dielectric Behaviour ◽  
Frequency Range ◽  
Wide Range ◽  
Dielectric Permittivity And Loss

The dielectric behaviour of composites with epoxy resin and kevlar fibres is investigated in a wide range of frequency and temperature. Dielectric permittivity is increasing with filler content and temperature, being always higher in the low frequency range. Dielectric permittivity and loss of the composites is mostly affected by interfacial polarization arising from inhomogeneities at interfaces introduced by the filler.

Theoretical investigation of dielectric properties of rare earth stillwellite compounds

2015 ◽  
Vol 29 (21) ◽  
pp. 1550154
Author(s):  
R. Shaltaf ◽  
J. Khalifeh
Keyword(s):  
Electronic Structure ◽  
Rare Earth ◽  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Density Functional ◽  
Structural Parameters ◽  
The Other ◽  
Static Dielectric Permittivity ◽  
Dielectric Tensors

Ab initio density functional calculations are performed to investigate the dielectric properties of LnBSiO 5 (Ln = Ce, Pr, Nd) with the stillwellite structure. The calculated structural parameters are found to agree well with existing experimental results. The three compounds possess insulating electronic structure with nearly isotropic high frequency dielectric permittivity tensors. On the other hand, the static dielectric permittivity tensors are found to be less isotropic. The anisotropy of static dielectric tensors are found to increase as the atomic number of the lanthanide increases.

scholarly journals Tunable Liquid Dielectric Antenna

2012 ◽  
Vol 1 (3) ◽  
pp. 223
Author(s):  
Kamal Raj Singh Rajoriya ◽  
P.K. Singhal
Keyword(s):  
Dielectric Properties ◽  
High Frequency ◽  
Dielectric Resonator ◽  
Return Loss ◽  
Pure Water ◽  
Liquid Dielectric ◽  
Dielectric Antenna ◽  
Dielectric Resonator Antennas ◽  
Wide Range ◽  
Molar Solution

This paper presents on modified the dielectric properties of liquid with varying salinity that was based on monopole structure. Dielectric resonator antennas (DRAs) can be made with a wide range of materials and allow many excitation methods [2]. Pure water does not work at high frequency (> 1 GHz) but increase in the salinity of water modifies the dielectric properties of water. Here proposed antenna shows that when the salinity increases in form of molar solution, the antenna was tuned at different frequency with increases return loss.

scholarly journals Low-Dissipation Thermosets Derived from Oligo(2,6-dimethyl phenylene oxide)-containing Benzoxazines

2018 ◽  
Author(s):  
Chien-Han Chen ◽  
Kuan-Wei Lee ◽  
Ching-Hsuan Lin ◽  
Tzong-Yuan Juang
Keyword(s):  
Dielectric Properties ◽  
Nucleophilic Substitution ◽  
Catalytic Hydrogenation ◽  
High Frequency ◽  
Main Chain ◽  
Dissipation Factor ◽  
Insulating Materials ◽  
Phenylene Oxide ◽  
Low Dissipation ◽  
Chain Type

Poly(2,6-dimethyl phenyl oxide) (PPO) is known for its low dissipation factor. To achieve insulating materials with low dissipation factor for high-frequency communication application, a monomer-type benzoxazine (P-APPO) and a main-chain-type benzoxazine (BPA-APPO) were prepared from an amine end-capped oligo (2,6-dimethyl phenylene oxide) (APPO). The APPO was prepared from a nucleophilic substitution of a phenol-end capped oligo (2,6-dimethyl phenylene oxide) (a commercial product, SA 90) with fluoronitrobenzene, and followed by catalytic hydrogenation. After self-curing or curing with a dicyclopentadiene-phenol epoxy (HP 7200), thermosets with high-Tg and low-dissipation factor can be achieved. Furthermore, the resulting epoxy thermosets show better thermal and dielectric properties than those of epoxy thermoset cured from its precursor SA90, demonstrating it is a successful modification in simultaneously enhancing the thermal and dielectric properties.

Dielectric Properties for the Ring Opening Polymerisation of ε-Caprolactone

2014 ◽  
Vol 493 ◽  
pp. 621-627 ◽  
Author(s):  
Mohd Johari Kamaruddin ◽  
Muhammad Abbas Ahmad Zaini ◽  
Anwar Johari ◽  
Tuan Amran Tuan Abdullah
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Penetration Depth ◽  
Scale Up ◽  
Small Diameter ◽  
Dissipation Factor ◽  
Bulk Temperature ◽  
Scale Production ◽  
Microwave Assisted ◽  
Wide Range

A dielectric property study was performed across a wide range of frequencies and temperatures onring opening polymerisation of ε-caprolactone system in order to relate quantitatively their dielectric properties to microwave heating mechanisms. An analysis of the results concluded that heating mechanism of the polymerisation mixtures in a microwave field was controlled by the dielectric properties of monomer, where the monomer was the major component (>90 % volume/volume) as well as the component with highest dielectric loss and dissipation factor. The penetration depth of mixtures at 2.45 GHz was noted to increase from ~0.58 cm (at 20 C) to ~3.3 cm (at 150 °C). This small penetration depth limits the potential to achieve the successful scale up of a microwave-assisted polymerisation of ε-caprolactone in batch mode at 2.45 GHz. As a result, this will lead to inhomogeneous bulk temperature distribution within the polymerisation mixture and irreproducible chemistry. However, a fast heating rate based on a high value of dissipation factor and dielectric loss of the polymerisation mixtures shows potential to enable the reaction to be completed in a few seconds that may allow the polymerisation to be transferred to a continuous flow process. In so doing, small diameter tubular reactors can be employed hence removing this penetration depth issue. Thus, the polymerisation mixtures dielectric properties are worth to be considered to ensure the reliability and reproducibility of the microwave assisted synthesis of poly-ε-caprolactone at large scale production.

scholarly journals Assessing evidence for adaptive evolution in two hearing-related genes important for high-frequency hearing in echolocating mammals

2021 ◽  
Author(s):  
Hui Wang ◽  
Hanbo Zhao ◽  
Yujia Chu ◽  
Jiang Feng ◽  
Keping Sun
Keyword(s):  
Adaptive Evolution ◽  
Hair Cells ◽  
High Frequency ◽  
Phylogenetic Trees ◽  
Outer Hair Cells ◽  
Functional Domain ◽  
Coding Region ◽  
Selective Pressures ◽  
Wide Range ◽  
Different Parts

Abstract High-frequency hearing is particularly important for echolocating bats and toothed whales. Previously, studies of the hearing-related genes Prestin, KCNQ4, and TMC1 documented that adaptive evolution of high-frequency hearing has taken place in echolocating bats and toothed whales. In this study, we present two additional candidate hearing-related genes, Shh and SK2, that may also have contributed to the evolution of echolocation in mammals. Shh is a member of the vertebrate Hedgehog gene family and is required in the specification of the mammalian cochlea. SK2 is expressed in both inner and outer hair cells, and it plays an important role in the auditory system. The coding region sequences of Shh and SK2 were obtained from a wide range of mammals with and without echolocating ability. The topologies of phylogenetic trees constructed using Shh and SK2 were different; however, multiple molecular evolutionary analyses showed that those two genes experienced different selective pressures in echolocating bats and toothed whales compared to non-echolocating mammals. In addition, several nominally significant positively selected sites were detected in the non-functional domain of the SK2 gene, indicating that different selective pressures were acting on different parts of the SK2 gene. This study has expanded our knowledge of the adaptive evolution of high-frequency hearing in echolocating mammals.

Parasites in Antarctic krill guts inferred from DNA sequences

2019 ◽  
Vol 31 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Alison C. Cleary ◽  
Maria C. Casas ◽  
Edward G. Durbin ◽  
Jaime Gómez-Gutiérrez
Keyword(s):  
Dna Sequences ◽  
High Frequency ◽  
Dna Analysis ◽  
Antarctic Krill ◽  
Euphausia Superba ◽  
Gut Contents ◽  
The West ◽  
West Antarctic ◽  
Wide Range

AbstractThe keystone role of Antarctic krill,Euphausia superbaDana, in Southern Ocean ecosystems, means it is essential to understand the factors controlling their abundance and secondary production. One such factor that remains poorly known is the role of parasites. A recent study of krill diet using DNA analysis of gut contents provided a snapshot of the parasites present within 170E. superbaguts in a small area along the West Antarctic Peninsula. These parasites includedMetschnikowiaspp. fungi,Haptoglossasp. peronosporomycetes,LankesteriaandParalecudinaspp. apicomplexa,Stegophorussp. nematodes, andPseudocolliniaspp. ciliates. Of these parasites,Metschnikowiaspp. fungi andPseudocolliniaspp. ciliates had previously been observed inE. superba, as had other genera of apicomplexans, though notLankesteriaandParalecudina.In contrast, nematodes had previously only been observed in eggs ofE. superba, and there are no literature reports of peronosporomycetes in euphausiids.Pseudocolliniaspp., parasitoids which obligately kill their host, were the most frequently observed infection, with a prevalence of 12%. The wide range of observed parasites and the relatively high frequency of infections suggest parasites may play a more important role than previously acknowledged inE. superbaecology and population dynamics.

scholarly journals High frequency and wide range of human kidney papillary crystalline plugs

Urolithiasis ◽  
2017 ◽  
Vol 46 (4) ◽  
pp. 333-341 ◽  
Author(s):  
Léa Huguet ◽  
Marine Le Dudal ◽  
Marine Livrozet ◽  
Dominique Bazin ◽  
Vincent Frochot ◽  
...  
Keyword(s):  
High Frequency ◽  
Human Kidney ◽  
Wide Range
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