scholarly journals Analysis of Electromagnetic Propagation from MHz to THz with a Memory-Optimised CPML-FDTD Algorithm

2018 ◽  
Vol 2018 ◽  
pp. 1-20
Author(s):  
A. Rodríguez-Sánchez ◽  
C. Couder-Castañeda ◽  
J. J. Hernández-Gómez ◽  
I. Medina ◽  
S. Peña-Ruiz ◽  
...  
Keyword(s):  
High Frequency ◽  
Fdtd Method ◽  
Research Area ◽  
Algorithm Analysis ◽  
Double Precision ◽  
Electromagnetic Propagation ◽  
High Frequencies ◽  
Extensive Analysis ◽  
Wide Range ◽  
Precision And Accuracy

FDTD method opened a fertile research area on the numerical analysis of electromagnetic phenomena under a wide range of media and propagation conditions, providing an extensive analysis of electromagnetic behaviour like propagation, reflection, refraction, and multitrajectory phenomena. In this paper, we present an optimised FDTD-CPML algorithm, focused in saving memory while increasing the performance of the algorithm. We particularly implement FDTD-CPML method at high frequency bands, used in several telecommunications applications as well as in nanoelectromagnetism. We show an analysis of the performance of the algorithm in single and double precision, as well as a stability of the algorithm analysis, from where we conclude that the implemented CPML ABC constitutes a robust choice in terms of precision and accuracy for the high frequencies herein considered. It is important to recall that the CPML ABC parameters provided in this paper are fixed for the tested range of frequencies, that is, from MHz to THz.

scholarly journals Optimization of subharmonic generation from ultrasound contrast agents at high frequency ultrasound

2021 ◽  
Author(s):  
Sara Iradji
Keyword(s):  
Contrast Agents ◽  
High Frequency ◽  
Ultrasound Contrast Agents ◽  
Surrounding Tissue ◽  
High Frequency Ultrasound ◽  
High Frequencies ◽  
Ultrasound Contrast ◽  
Wide Range ◽  
Frequency Ultrasound

The microcirculation can be differentiated from the surrounding tissue using high frequency ultrasound subharmonic imaging. This imaging technique relies on the detection of energy scattered from ultrasound contrast agents at half the transmit frequency due to their resonant oscillations. The current contrast agents and the subharmonic imaging parameters have not been optimized for high frequencies. Moreover, the origin of subharmonic generation from submicron bubbles is not well-understood. The size distribution of Definity™ phospholipid-shelled microbubbles was altered to find the optimal bubble size to be resonant over a wide range of high frequencies. The resonant behaviour of bubbles was investigated through in vitro attenuation measurements. The transmit frequency and pressure were varied to optimize the backscattered subharmonic signal. Alteration of Definity™ population significanatly improved the scattering for subharmonic imaging at 20 MHz. A peak negative pressure between 400 to 600 kPa is suggested for this frequency range.

scholarly journals Optimization of subharmonic generation from ultrasound contrast agents at high frequency ultrasound

2021 ◽  
Author(s):  
Sara Iradji
Keyword(s):  
Contrast Agents ◽  
High Frequency ◽  
Ultrasound Contrast Agents ◽  
Surrounding Tissue ◽  
High Frequency Ultrasound ◽  
High Frequencies ◽  
Ultrasound Contrast ◽  
Wide Range ◽  
Frequency Ultrasound

The microcirculation can be differentiated from the surrounding tissue using high frequency ultrasound subharmonic imaging. This imaging technique relies on the detection of energy scattered from ultrasound contrast agents at half the transmit frequency due to their resonant oscillations. The current contrast agents and the subharmonic imaging parameters have not been optimized for high frequencies. Moreover, the origin of subharmonic generation from submicron bubbles is not well-understood. The size distribution of Definity™ phospholipid-shelled microbubbles was altered to find the optimal bubble size to be resonant over a wide range of high frequencies. The resonant behaviour of bubbles was investigated through in vitro attenuation measurements. The transmit frequency and pressure were varied to optimize the backscattered subharmonic signal. Alteration of Definity™ population significanatly improved the scattering for subharmonic imaging at 20 MHz. A peak negative pressure between 400 to 600 kPa is suggested for this frequency range.

scholarly journals Selective Extraction of Entangled Textures via Adaptive PDE Transform

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Yang Wang ◽  
Guo-Wei Wei ◽  
Siyang Yang
Keyword(s):  
High Frequency ◽  
Local Variation ◽  
Selective Extraction ◽  
Research Area ◽  
Natural Landscape ◽  
Mode Decomposition ◽  
Wide Range ◽  
Important Research Area ◽  
Variation Of Functional ◽  
Functional Mode

Texture and feature extraction is an important research area with a wide range of applications in science and technology. Selective extraction of entangled textures is a challenging task due to spatial entanglement, orientation mixing, and high-frequency overlapping. The partial differential equation (PDE) transform is an efficient method for functional mode decomposition. The present work introduces adaptive PDE transform algorithm to appropriately threshold the statistical variance of the local variation of functional modes. The proposed adaptive PDE transform is applied to the selective extraction of entangled textures. Successful separations of human face, clothes, background, natural landscape, text, forest, camouflaged sniper and neuron skeletons have validated the proposed method.

High Frequency Electromagnetic Propagation/Scattering

2000 ◽  
Author(s):  
Vladimir Oliker ◽  
Bjorn Engquist ◽  
Stanley Osher
Keyword(s):  
High Frequency ◽  
Electromagnetic Propagation

Pharmaceutical Co-Crystals - Design, Development and Applications

2020 ◽  
Vol 10 (3) ◽  
pp. 169-184
Author(s):  
Rachna Anand ◽  
Arun Kumar ◽  
Arun Nanda
Keyword(s):  
Physicochemical Properties ◽  
Crystal Engineering ◽  
Pharmacological Action ◽  
Physicochemical Characteristics ◽  
Research Area ◽  
Dissolution Profile ◽  
Design Development ◽  
Drug Molecule ◽  
Wide Range ◽  
Major Factors

Background: Solubility and dissolution profile are the major factors which directly affect the biological activity of a drug and these factors are governed by the physicochemical properties of the drug. Crystal engineering is a newer and promising approach to improve physicochemical characteristics of a drug without any change in its pharmacological action through a selection of a wide range of easily available crystal formers. Objective: The goal of this review is to summarize the importance of crystal engineering in improving the physicochemical properties of a drug, methods of design, development, and applications of cocrystals along with future trends in research of pharmaceutical co-crystals. Co-crystallization can also be carried out for the molecules which lack ionizable functional groups, unlike salts which require ionizable groups. Conclusion: Co-crystals is an interesting and promising research area amongst pharmaceutical scientists to fine-tune the physicochemical properties of drug materials. Co-crystallization can be a tool to increase the lifecycle of an older drug molecule. Crystal engineering carries the potential of being an advantageous technique than any other approach used in the pharmaceutical industry. Crystal engineering offers a plethora of biopharmaceutical and physicochemical enhancements to a drug molecule without the need of any pharmacological change in the drug.

scholarly journals Anti-Biofilm Molecules Targeting Functional Amyloids

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 795
Author(s):  
Leticia Matilla-Cuenca ◽  
Alejandro Toledo-Arana ◽  
Jaione Valle
Keyword(s):  
Biofilm Formation ◽  
Therapeutic Strategy ◽  
Research Area ◽  
Therapeutic Strategies ◽  
Structural Components ◽  
Significant Issue ◽  
Wide Range ◽  
Effective Therapeutic Strategy ◽  
Functional Amyloids ◽  
Biofilm Matrix

The choice of an effective therapeutic strategy in the treatment of biofilm-related infections is a significant issue. Amyloids, which have been historically related to human diseases, are now considered to be prevailing structural components of the biofilm matrix in a wide range of bacteria. This assumption creates the potential for an exciting research area, in which functional amyloids are considered to be attractive targets for drug development to dissemble biofilm structures. The present review describes the best-characterized bacterial functional amyloids and focuses on anti-biofilm agents that target intrinsic and facultative amyloids. This study provides a better understanding of the different modes of actions of the anti-amyloid molecules to inhibit biofilm formation. This information can be further exploited to improve the therapeutic strategies to combat biofilm-related infections.

scholarly journals Rheology of rounded mammalian cells over continuous high-frequencies

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gotthold Fläschner ◽  
Cosmin I. Roman ◽  
Nico Strohmeyer ◽  
David Martinez-Martin ◽  
Daniel J. Müller
Keyword(s):  
High Frequency ◽  
Mammalian Cells ◽  
Mechanical Response ◽  
Cell Mass ◽  
Low Frequency ◽  
Mass Measurements ◽  
High Frequencies ◽  
Polymer Relaxation ◽  
Continuous Frequency ◽  
Rheological Experiments

AbstractUnderstanding the viscoelastic properties of living cells and their relation to cell state and morphology remains challenging. Low-frequency mechanical perturbations have contributed considerably to the understanding, yet higher frequencies promise to elucidate the link between cellular and molecular properties, such as polymer relaxation and monomer reaction kinetics. Here, we introduce an assay, that uses an actuated microcantilever to confine a single, rounded cell on a second microcantilever, which measures the cell mechanical response across a continuous frequency range ≈ 1–40 kHz. Cell mass measurements and optical microscopy are co-implemented. The fast, high-frequency measurements are applied to rheologically monitor cellular stiffening. We find that the rheology of rounded HeLa cells obeys a cytoskeleton-dependent power-law, similar to spread cells. Cell size and viscoelasticity are uncorrelated, which contrasts an assumption based on the Laplace law. Together with the presented theory of mechanical de-embedding, our assay is generally applicable to other rheological experiments.

scholarly journals An Overview on the Rheology, Mechanical Properties, Durability, 3D Printing, and Microstructural Performance of Nanomaterials in Cementitious Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2950
Author(s):  
Hongwei Song ◽  
Xinle Li
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Research Area ◽  
Cementitious Composites ◽  
Split Tensile Strength ◽  
Contour Crafting ◽  
Wide Range ◽  
Active Research

The most active research area is nanotechnology in cementitious composites, which has a wide range of applications and has achieved popularity over the last three decades. Nanoparticles (NPs) have emerged as possible materials to be used in the field of civil engineering. Previous research has concentrated on evaluating the effect of different NPs in cementitious materials to alter material characteristics. In order to provide a broad understanding of how nanomaterials (NMs) can be used, this paper critically evaluates previous research on the influence of rheology, mechanical properties, durability, 3D printing, and microstructural performance on cementitious materials. The flow properties of fresh cementitious composites can be measured using rheology and slump. Mechanical properties such as compressive, flexural, and split tensile strength reveal hardened properties. The necessary tests for determining a NM’s durability in concrete are shrinkage, pore structure and porosity, and permeability. The advent of modern 3D printing technologies is suitable for structural printing, such as contour crafting and binder jetting. Three-dimensional (3D) printing has opened up new avenues for the building and construction industry to become more digital. Regardless of the material science, a range of problems must be tackled, including developing smart cementitious composites suitable for 3D structural printing. According to the scanning electron microscopy results, the addition of NMs to cementitious materials results in a denser and improved microstructure with more hydration products. This paper provides valuable information and details about the rheology, mechanical properties, durability, 3D printing, and microstructural performance of cementitious materials with NMs and encourages further research.

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.

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