74 results match your criteria AIP Advances[Journal]

A 3D finite element model to study the cavitation induced stresses on blood-vessel wall during the ultrasound-only phase of photo-mediated ultrasound therapy.

AIP Adv 2022 Apr 19;12(4):045020. Epub 2022 Apr 19.

Institute for Bioengineering Research and Department of Mechanical Engineering, University of Kansas, Lawrence, Kansas 66045, USA.

Photo-mediated ultrasound therapy (PUT) is a novel technique utilizing synchronized ultrasound and laser to generate enhanced cavitation inside blood vessels. The enhanced cavitation inside blood vessels induces bio-effects, which can result in the removal of micro-vessels and the reduction in local blood perfusion. These bio-effects have the potential to treat neovascularization diseases in the eye, such as age-related macular degeneration and diabetic retinopathy. Read More

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Simulating stochastic adsorption of diluted solute molecules at interfaces.

Jixin Chen

AIP Adv 2022 Jan 11;12(1):015318. Epub 2022 Jan 11.

Department of Chemistry and Biochemistry, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA.

This report uses Monte Carlo simulations to connect stochastic single-molecule and ensemble surface adsorption of molecules from dilute solutions. Monte Carlo simulations often use a fundamental time resolution to simulate each discrete step for each molecule. The adsorption rate obtained from such a simulation surprisingly contains an error compared to the results obtained from the traditional method. Read More

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January 2022

Airborne virus transmission under different weather conditions.

AIP Adv 2022 Jan 13;12(1):015019. Epub 2022 Jan 13.

School of Physical Sciences, Indian Institute of Technology Goa, Ponda 403401, Goa, India.

The COVID19 infection is known to disseminate through droplets ejected by infected individuals during coughing, sneezing, speaking, and breathing. The spread of the infection and hence its menace depend on how the virus-loaded droplets evolve in space and time with changing environmental conditions. In view of this, we investigate the evolution of the droplets within the purview of the Brownian motion of the evaporating droplets in the air with varying weather conditions under the action of gravity. Read More

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January 2022

Reducing indoor particle exposure using mobile air purifiers-Experimental and numerical analysis.

AIP Adv 2021 Dec 9;11(12):125114. Epub 2021 Dec 9.

Institute of Flow in Additively Manufactured Porous Media (ISAPS), Heilbronn University of Applied Sciences, Max-Planck-Str. 39, 74081 Heilbronn, Germany.

Aerosol particles are one of the main routes of transmission of COVID-19. Mobile air purifiers are used to reduce the risk of infection indoors. We focus on an air purifier that generates a defined volumetric air flow through a highly efficient filter material. Read More

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December 2021

Experimental study of the dispersion of cough-generated droplets from a person going up- or downstairs.

AIP Adv 2022 Jan 3;12(1):015002. Epub 2022 Jan 3.

The dispersion of cough-generated droplets from a person going up- or downstairs was investigated through a laboratory experiment in a water tunnel. This experiment was carried out with a manikin mounted at inclination angles facing the incoming flow to mimic a person going up or down. Detailed velocity measurements and flow visualization were conducted in the water tunnel experiments. Read More

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January 2022

Dynamic strain evolution in an optically excited Pt thin film.

AIP Adv 2021 Nov 8;11(11):115111. Epub 2021 Nov 8.

Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA.

The structural evolution of a Pt thin film following photo-thermal excitation by 1 ps optical laser pulses was studied with a time resolution of 100 ps over a total time period of 1 ms. Laser pulse fluences below 50 mJ/cm were insufficient to relax the residual stress state of the as-prepared film even after 10 000 pulses. In this fluence regime, a rapid initial lattice expansion and a decrease in the lattice coherence length due to ultrafast photo-thermal heating were observed. Read More

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November 2021

Development of a rapid plasma decontamination system for decontamination and reuse of filtering facepiece respirators.

AIP Adv 2021 Oct 7;11(10):105311. Epub 2021 Oct 7.

School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom.

The COVID-19 pandemic has caused a high demand for filtering facepiece respirators (FFRs), which has brought global challenges in sustaining the supply chain for FFRs. Because respirators are basic personal protective equipment to protect frontline healthcare workers against COVID-19, the chronic, global shortage of N95/N99 masks is one of the most urgent threats to our collective ability to save lives from the coronavirus. The reuse of masks may need to be considered as a crisis capacity strategy to ensure continued availability even though most of the masks are considered one-time use. Read More

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October 2021

Effects of surface charge and environmental factors on the electrostatic interaction of fiber with virus-like particle: A case of coronavirus.

AIP Adv 2021 Oct 7;11(10):105008. Epub 2021 Oct 7.

Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi, Vietnam.

We propose a theoretical model to elucidate intermolecular electrostatic interactions between a virus and a substrate. Our model treats the virus as a homogeneous particle having surface charge and the polymer fiber of the respirator as a charged plane. Electric potentials surrounding the virus and fiber are influenced by the surface charge distribution of the virus. Read More

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October 2021

On the utility of a well-mixed model for predicting disease transmission on an urban bus.

AIP Adv 2021 Aug 25;11(8):085229. Epub 2021 Aug 25.

Department of Naval Architecture and Marine Engineering, University of Michigan, Ann Arbor, Michigan 48109-2145, USA.

The transport of virus-laden aerosols from a host to a susceptible person is governed by complex turbulent airflow and physics related to breathing, coughing and sneezing, mechanical and passive ventilation, thermal buoyancy effects, surface deposition, masks, and air filtration. In this paper, we study the infection risk via airborne transmission on an urban bus using unsteady Reynolds-averaged Navier-Stokes equations and a passive-scalar model of the virus-laden aerosol concentration. Results from these simulations are directly compared to the widely used well-mixed model and show significant differences in the concentration field and number of inhaled particles. Read More

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Cold atmospheric plasma: A non-negligible strategy for viral RNA inactivation to prevent SARS-CoV-2 environmental transmission.

AIP Adv 2021 Aug 10;11(8):085019. Epub 2021 Aug 10.

Anhui Academy of Medical Sciences, Hefei, China.

Cold atmospheric plasma (CAP), regarded as a powerful physics technology, displays antimicrobial, antitumor, and even antiviral properties, but the underlying mechanism is rarely studied. In this study, four CAP exposure doses (30, 60, 120, and 240 s) were applied to inactivate a severe acute respiratory syndrome coronavirus 2 like pseudovirus on a stainless steel disk, which comprised spike protein on its membrane and can express a green fluorescent protein. In order to unravel the potential effects of CAP irradiation on pseudovirus, infection assay, optical emission spectra analysis, transmission electron microscopy (TEM), sodium dodecyl sulfate polyacrylamide gel electrophoresis, ELISA, and qPCR experiments were carried out. Read More

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Impact of grain orientation and phase on Volta potential differences in an additively manufactured titanium alloy.

AIP Adv 2021 ;11(2)

Material Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305, USA.

This work introduces a method for co-localized multi-modal imaging of sub-m features in an additively manufactured (AM) titanium alloy. Ti-6Al-4V parts manufactured by electron beam melting powder bed fusion were subjected to hot isostatic pressing to seal internal porosity and machined to remove contour-hatch interfaces. Electron microscopy and atomic force microscopy-based techniques (electron backscatter diffraction and scanning Kelvin probe force microscopy) were used to measure and categorize the effects of crystallographic texture, misorientation, and phase content on the relative differences in the Volta potential of -Ti and -Ti phases. Read More

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January 2021

Nano-layered surface plasmon resonance-based highly sensitive biosensor for virus detection: A theoretical approach to detect SARS-CoV-2.

AIP Adv 2021 Jun 14;11(6):065023. Epub 2021 Jun 14.

Department of Electrical and Electronic Engineering, Khulna University of Engineering and Technology, Khulna 9203, Bangladesh.

The outbreak of the coronavirus disease (COVID-19) pandemic has become a worldwide health catastrophe instigated by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). Countries are battling to slow the spread of this virus by testing and treating patients, along with other measures such as prohibiting large gatherings, maintaining social distance, and frequent, thorough hand washing, as no vaccines or medicines are available that could effectively treat infected people for different types of SARS-CoV-2 variants. However, the testing procedure to detect this virus is lengthy. Read More

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Nanowaveguide-illuminated fluorescence correlation spectroscopy for single molecule studies.

AIP Adv 2021 Jun 4;11(6):065112. Epub 2021 Jun 4.

Department of Physics and Astronomy, San Francisco State University, 1600 Holloway Avenue, San Francisco, California 94132, USA.

Fluorescence Correlation Spectroscopy (FCS) is a method of investigating concentration fluctuations of fluorescent particles typically in the nM range as a result of its femtoliter-sized sample volume. However, biological processes on cell membranes that involve molecules in the μM concentration range require sample volumes well below the conventional FCS limit as well as nanoscale confinement in the longitudinal direction. In this study, we show that an effective measurement volume down to the zeptoliter range can be achieved via the introduction of a nanowire waveguide, resulting in an illumination spot of about 50 nm in lateral dimensions and a longitudinal confinement of around 20 nm just above the waveguide exit surface. Read More

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COVID-19 pandemic, lockdown, and consequences for a fossil fuel-dominated electricity system.

AIP Adv 2021 May 5;11(5):055307. Epub 2021 May 5.

Department of Electrical and Electronic Engineering, Jashore University of Science and Technology, Jashore 7408, Bangladesh.

In South Asian countries, the spread of COVID-19 was not treated seriously until mid-March 2020. Measures similar to those considered in Europe and other developed countries, such as maintaining social distance and lockdowns, were imposed. Lockdowns imposed a significant impact on the power sector, and this has been well explored in the literature for developed countries. Read More

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Understanding the sodium cation conductivity of human epileptic brain tissue.

AIP Adv 2021 Apr 16;11(4):045118. Epub 2021 Apr 16.

Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095, USA.

Transient and frequency-dependent conductivity measurements on excised brain-tissue lesions from epilepsy patients indicate that sodium cations are the predominant charge carriers. The transient conductivity ultimately vanishes as ions encounter blockages. The initial and final values of the transient conductivity correspond to the high-frequency and low-frequency limits of the frequency-dependent conductivity, respectively. Read More

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Continuous and discrete phasor analysis of binned or time-gated periodic decays.

Xavier Michalet

AIP Adv 2021 Mar 23;11(3):035331. Epub 2021 Mar 23.

Department of Chemistry and Biochemistry, 607 Charles E. Young Drive E., Los Angeles, California 90095, USA.

The time-resolved analysis of periodically excited luminescence decays by the phasor method in the presence of time-gating or binning is revisited. Analytical expressions for discrete configurations of square gates are derived, and the locus of the phasors of such modified periodic single-exponential decays is compared to the canonical universal semicircle. The effects of instrument response function offset, decay truncation, and gate shape are also discussed. Read More

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Design and characterization of telecentric f- scanning lenses for broadband terahertz frequency systems.

AIP Adv 2020 Dec 11;10(12):125313. Epub 2020 Dec 11.

Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, USA.

Telecentric beam scanning using f- lenses offers nearly uniform spot size, linear beam displacement, and normal incidence angle over a planar surface. These unique properties allow for the minimization of imaging distortion over a wide field-of-view. In this article, we present a numerical method for designing custom f- lenses in the THz regime. Read More

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December 2020

A modified SEIR model applied to the data of COVID-19 spread in Saudi Arabia.

AIP Adv 2020 Dec 4;10(12):125210. Epub 2020 Dec 4.

Science and Technology Unit (STU), Umm Al-Qura University, Makkah 21955, Saudi Arabia.

The Susceptible-Exposed-Infectious-Recovered (SEIR) model is an established and appropriate approach in many countries to ascertain the spread of the coronavirus disease 2019 (COVID-19) epidemic. We wished to create a new COVID-19 model to be suitable for patients in any country. In this work, a modified SEIR model was constructed. Read More

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December 2020

Pandemic infection rates are deterministic but cannot be modeled.

AIP Adv 2020 Nov 24;10(11):115023. Epub 2020 Nov 24.

Physics Department, University of Houston, Houston, Texas 77204, USA.

The covid-19 infection rates for a large number of infections collected from a large number of different sites are well defined with a negligible scatter. The simplest invertible iterated map, exponential growth and decay, emerges from country-wide histograms whenever Tchebychev's inequality is satisfied to within several decimal places. This is one point. Read More

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November 2020

A novel methodology and new concept of SARS-CoV-2 elimination in heating and ventilating air conditioning systems using waste heat recovery.

AIP Adv 2020 Aug 4;10(8):085308. Epub 2020 Aug 4.

Urmia University of Medical Sciences, Department of Dermatology and Infectious Diseases, Urmia, Iran.

Heating and ventilation air conditioning systems in hospitals (cleanroom HVAC systems) are used to control the transmission/spreading of airborne diseases such as COVID-19. Air exiting from these systems may contribute to the spreading of coronavirus droplets outside of hospitals. Some research studies indicate that the shortest time of survival of SARS-CoV-2 in aerosol form (as droplets in the air) is four hours and the virus becomes inactive above 60 °C air temperature. Read More

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Transient acoustic vaporization signatures unique to low boiling point phase change contrast agents enable super-resolution ultrasound imaging without spatiotemporal filtering.

AIP Adv 2020 Oct 19;10(10):105124. Epub 2020 Oct 19.

Joint Department of Biomedical Engineering, University of North Carolina-Chapel Hill and North Carolina State University, 116 Manning Drive, 9018 Mary Ellen Jones Building, CB7575, Chapel Hill, North Carolina 27599, USA.

The unique activation signal of phase-change contrast agents (PCCAs or droplets) can be separated from the tissue signal and localized to generate super-resolution (SR) ultrasound (US) images. Lipid-shelled, perfluorocarbon PCCAs can be stochastically vaporized (activated) by a plane wave US transmission thereby enabling them to be used as separable targets for ultrasound localization microscopy. The unique signature of droplet vaporization imaging and the transient inherent nature of this signature increases signal contrast and therefore localization confidence, while the poor resolution of the low-frequency vaporization signal is overcome by the super-resolution result. Read More

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October 2020

Fluid surface tension evaluation using capillary wave measurement with optical coherence tomography.

AIP Adv 2020 May 19;10(5):055121. Epub 2020 May 19.

Department of Robotics and Mechatronics, AGH University of Science and Technology, Al. Mickiewicza 30, Krakow 30-059, Poland.

The surface tension of biological fluids is an important parameter because the mechanical properties of fluids are closely linked with hematological diseases and other pathophysiologies. Capillary waves are associated with fluid mechanical properties. Here, we propose a method that utilizes the acoustic radiation force (ARF) to generate propagating waves and optical coherence tomography (OCT) to measure the wave motion. Read More

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An adapted particle swarm optimization algorithm as a model for exploring premyofibril formation.

AIP Adv 2020 Apr 17;10(4):045126. Epub 2020 Apr 17.

While the fundamental steps outlining myofibril formation share a similar scheme for different cell and species types, various granular details involved in the development of a functional contractile muscle are not well understood. Many studies of myofibrillogenesis focus on the protein interactions that are involved in myofibril maturation with the assumption that there is a fully formed premyofibril at the start of the process. However, there is little known regarding how the premyofibril is initially constructed. Read More

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Flow physics and mixing quality in a confined impinging jet mixer.

AIP Adv 2020 Apr 2;10(4):045105. Epub 2020 Apr 2.

Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA.

Due to their ability to provide efficient mixing at small scales, confined impinging jet mixers (CIJMs) are employed widely in nanoparticle assembly processes such as flash nanoprecipitation and flash nanocomplexation, which require rapid mixing. In this mixing device, two jets from opposite directions impinge directly on each other forming a thin shear layer that breaks down rapidly into small flow structures. This enables effective mixing of the species transported by each jet by drastically reducing the diffusion distance. Read More

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Proton radiation effects on carrier transport in diamond radiation detectors.

AIP Adv 2020 Feb 3;10(2):025004. Epub 2020 Feb 3.

Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, USA.

Diamond, a highly radiation-resistant material, is considered a nearly ideal material for radiation detection, particularly in high-energy physics. In this study, radiation damage from high-energy proton beams was induced in diamond crystals to determine exposure lifetime in detectors made from this material; the effects were investigated using non-destructive x-ray techniques and through the FLUKA simulation package. Two diamond detectors were irradiated by an 800 MeV proton beam at different fluence rates, and the real-time current response was recorded to observe degradation in the signal over time. Read More

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February 2020

Integration of a rapid scanning technique into THz time-domain spectrometers for nonlinear THz spectroscopy measurements.

AIP Adv 2019 Mar 25;9(3):035348. Epub 2019 Mar 25.

Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany.

We have implemented a rapid scanning technique into THz time-domain spectrometers using an oscillating frictionless delay line, especially adapted for nonlinear THz experiments. Thereby we were able to increase the dynamic range of THz measurements in the frequency range from 40 to 200 cm by up to 24 dB and reduce the scanning time by up to a factor of 200. We report here test measurements on TDS-setups at repetition rates of 80 MHz and 5 kHz. Read More

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A double exponential potential for van der Waals interaction.

AIP Adv 2019 Jun 7;9(6):065304. Epub 2019 Jun 7.

Laboratory of Computational Biology, NHLBI, NIH, 12 South Dr., Bldg. 12A, Room 3053K, Bethesda, Maryland 20892, USA.

Van der Waals (vdw) interaction is an important force between atoms and molecules. Many potential functions have been proposed to model vdw interaction such as the Lennard-Jones (L-J) potential. To overcome certain drawbacks of existing function forms, this work proposes a double exponential (DE) potential that contains a repulsive exponential term and an attractive exponential term. Read More

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determination of exerted forces in magnetic pulling cytometry.

AIP Adv 2019 Mar 14;9(3):035221. Epub 2019 Mar 14.

Mechanical & Aerospace Engineering, Old Dominion University, Kaufman 238e, 1 Old Dominion University, Norfolk, Virginia 23529, USA.

Localized application of exogenous forces on soft biomaterials and cells is often essential for the study of their response to external mechanical stimuli. Magnetic means of applying forces, particularly those based on permanent magnets and magnetic beads coupled to substrates or cells provide an accessible means of exerting forces of appropriate magnitude. The amount of force exerted, however, is often inferred from calibration performed , with typically similar but different magnetic beads. Read More

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Micromagnetic study of soft magnetic nanowires.

AIP Adv 2019 ;9(12)

Department of Electrical and Computer Engineering, University of Akron, Akron, OH, 44325-3904, USA.

In this paper, micromagnetic analysis of an array of long magnetic nanowires (NWs) embedded in a nonmagnetic matrix is performed. It is found that for NWs with diameters on the order of a hundred nanometers, the anisotropy and exchange energies are negligible, so the total free energy is a sum of the Zeeman and magnetostatic energies. The minimum magnetostatic energy corresponds to the maximum Zeeman energy, whereby half of the NWs are magnetized parallel to the external field, while the rest of the NWs are magnetized antiparallel to the external fields. Read More

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January 2019

Investigation of femtosecond laser induced ripple formation on copper for varying incident angle.

AIP Adv 2018 10;8(1):015212. Epub 2018 Jan 10.

Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.

The hydrodynamic mechanisms associated with the formation of femtosecond laser induced ripples on copper for two angles of incidence are reported. Laser pulse length used for this work is 35 fs. A revised two-temperature model is presented that comprises transient changes of optical characteristics during the irradiation with femtosecond pulses to model relaxation processes and thermal response in bulk copper. Read More

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January 2018