94 results match your criteria: "National Institute for Standards[Affiliation]"

Article Synopsis
  • - A new eco-friendly method was created to produce nanoparticles from dried molokhia leaves, resulting in sustainable materials that act as flame retardants, antibacterial agents, and UV protectors for polymer films, specifically polyvinyl alcohol (PVA) nanocomposites.
  • - The nanoparticles, which are around 8.5 nm in size, significantly improved the flame retardancy and UV protection of PVA films, completely preventing burning and providing over 900% better UV protection compared to films without nanoparticles.
  • - The engineered nanoparticles also inhibited bacterial growth against common strains, offering clear inhibition zones, and a flame retardancy mechanism was proposed, along with an economic assessment for large-scale production of these sustainable nanoparticles.
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TL-SDA: A designed toolkit for the deconvolution analysis of thermoluminescence glow curves.

Appl Radiat Isot

April 2024

Nuclear Physics and Elementary Particles Physics Section, Physics Department, Aristotle University of Thessaloniki, Greece.

In the present study, a graphical user interface (GUI) toolkit has been developed to analyze the thermoluminescence (TL) glow-curve and evaluate the trapping parameters using TL expression based on the one-trap one-recombination model. The basic idea of the deconvolution analysis in the developed toolkit is based on performing a sequence of successful fits, where the information provided by each fit is used by the next fit until the deconvolution of the entire glow curve approaches an optimum solution. The starting values and ranges of the fitting parameters can be controlled and adjusted to improve the deconvolution analysis of complex structure glow curves.

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The CLC-ec1 chloride/proton antiporter is a membrane-embedded homodimer with subunits that can dissociate and associate, but the thermodynamic driving forces favor the assembled dimer at biological densities. Yet, the physical reasons for this stability are confounding as dimerization occurs via the burial of hydrophobic interfaces away from the lipid solvent. For binding of nonpolar surfaces in aqueous solution, the driving force is often attributed to the hydrophobic effect, but this should not apply in the membrane since there is very little water.

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Newly synthesized mono- and bis-thioureidophosphonate (MTP and BTP) analogues in eco-friendly conditions were employed as reducing/capping cores for 100, 500, and 1000 mg L of silver nitrate. The physicochemical properties of silver nanocomposites (MTP(BTP)/Ag NCs) were fully elucidated using spectroscopic and microscopic tools. The antibacterial activity of the nanocomposites was screened against six multidrug-resistant pathogenic strains, comparable to ampicillin and ciprofloxacin commercial drugs.

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Efficient chip-based optical parametric oscillators from 590 nm to 1150 nm.

Optica

January 2022

Joint Quantum Institute, NIST/University of Maryland, College Park, MD 20742 USA.

Optical parametric oscillators are widely used to generate coherent light at frequencies not accessible by conventional laser gain. However, chip-based parametric oscillators operating in the visible spectrum have suffered from pump-to-signal conversion efficiencies typically less than 0.1 %.

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Our current work intends to primarily engineer a new type of antibacterial composite by preparing a highly biocompatible graphene sheet decorated with TMC-CMS IPNs nanoparticles utilizing one-pot, green, cost-effective ultrasonication approach. The microstructure of as-formed materials was chemically confirmed using various analytical techniques such as H-NMR, FTIR, UV/vis, SEM, and TEM. TEM data has proved the formation of uniformly distributed TCNPs on graphene surfaces with a small particle size of ~22 nm compared with that of pure nanoparticles (~30 nm).

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Optical parametric oscillation in a Kerr nonlinear microresonator can generate coherent laser light with frequencies that are widely separated from the pump frequency, allowing, for example, visible light to be generated using a near-infrared pump. To be practically useful, the pump-to-signal conversion efficiency must be far higher than what has been demonstrated in microresonator-based oscillators with widely-separated output frequencies. To address this challenge, here we theoretically and numerically study parametric oscillations in Kerr nonlinear microresonators, revealing an intricate solution space that arises from an interplay of nonlinear processes.

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Uncertainty of LiF thermoluminescence at low dose levels: Experimental results.

Appl Radiat Isot

July 2022

Radiation Protection Department, Nuclear and Radiological Safety Research Center, Egyptian Atomic Energy Authority, Egypt.

The LiF:Mg,Ti (TLD-100) thermoluminescence (TL) detectors are widely used in many dosimetric applications, particularly in personal dosimetry area. In the present study, the uncertainty of TLD-100 measurements at the low dose levels has been assessed for different TL readout analysis methods. The criteria used to evaluate the minimum measurable dose (MMD) have been also investigated.

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During COVID-19 crisis, water pollution caused by pharmaceutical residuals have enormously aggravated since millions of patients worldwide are consuming tons of drugs daily. Antibiotics are the preponderance pharmaceutical pollutants in water bodies that surely cause a real threat to human life and ecosystems. The excellent characteristics of chitosan such as nontoxicity, easy functionality, biodegradability, availability in nature and the abundant hydroxyl and amine groups onto its backbone make it a promising adsorbent.

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Shielding glass materials doped with heavy metal oxides show an improvement in the effectiveness of the materials used in radiation shielding. In this work, the photon shielding parameters of six tellurite glass systems doped with several metal oxides namely, 70TeO2-10P2O5- 10ZnO- 5.0PbF2- 0.

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Enhanced optical and structural features of Ni/La hybrid borate glasses.

Spectrochim Acta A Mol Biomol Spectrosc

February 2022

Department of Physics, Faculty of Science, Al-Azhar University, (Girls' Branch), Cairo, Egypt.

Glasses with the formula [80BO-4.0LaO-(16-x) PbO-xNiO, (x ranged from 0.0 to 4.

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The tremendous development in the industrial sector leads to discharging of the several types of effluents containing detrimental contaminants into water sources. Lately, the proliferation of toxic anions particularly phosphates and nitrates onto aquatic systems certainly depreciates the ecological system and causes a deadly serious problem. Chitosan (Cs) is one of the most auspicious biopolymer adsorbents that are being daily developed for removing of various contaminants from polluted water.

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Side-grooved Charpy impact testing: Assessment of splitting and fracture properties of high-toughness plate steels.

Mater Sci Eng A Struct Mater

July 2021

ASPPRC, Department of Metallurgical and Materials Engineering, Colorado School of Mines, 1500 Illinois St., Golden, CO, USA.

The fracture properties and susceptibility to crack-divider delamination (or splitting) of three commercially produced high-toughness X70 pipeline steels are evaluated with Charpy impact test samples modified to incorporate side grooves. Temperature-dependent impact data are compared with standard Charpy V-notch (CVN) and drop weight tear test data (DWTT). It is shown that the modified geometry prevents the accumulation of plastic deformation at upper shelf energy temperatures and improves the accuracy of impact properties measurements.

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In this study, thermoluminescence detectors (TLD)-600 and TLD-700 were used under different conditions to study neutron dosimetry for its application in medical dosimetry as albedo dosimeters. LiF has a high cross-section for neutrons and is more sensitive to neutrons than to gamma radiation. Conversely, TLD-700 showed a better response to gamma radiation.

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Over two-thirds of integral membrane proteins of known structure assemble into oligomers. Yet, the forces that drive the association of these proteins remain to be delineated, as the lipid bilayer is a solvent environment that is both structurally and chemically complex. In this study, we reveal how the lipid solvent defines the dimerization equilibrium of the CLC-ec1 Cl/H antiporter.

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Background: Metal oxide glass composites have attracted huge interest as promising shielding materials to replace toxic, heavy, and costly conventional shielding materials.

Objective: In this work, we evaluate shielding effectiveness of four novel tellurite-based glasses samples doped with oxide metals (namely, A, B, C, and D, which are 75TeO2- 10P2O5- 10ZnO- 5PbF2- 0.24Er2O3 ; 70TeO2- 10P2O5- 10ZnO- 5PbF2 -5MgO- 0.

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Anion exchange membrane fuel cells (AEMFC) are potentially very low-cost replacements for proton exchange membrane fuel cells. However, AEMFCs suffer from one very serious drawback: significant performance loss when CO is present in the reacting oxidant gas (e.g.

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Under-reporting of greenhouse gas emissions in U.S. cities.

Nat Commun

February 2021

Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France.

Cities dominate greenhouse gas emissions. Many have generated self-reported emission inventories, but their value to emissions mitigation depends on their accuracy, which remains untested. Here, we compare self-reported inventories from 48 US cities to independent estimates from the Vulcan carbon dioxide emissions data product, which is consistent with atmospheric measurements.

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This study provides a unified presentation of thermoluminescence (TL) glow-curve deconvolution within the framework of the open source R package "tgcd", according to various analytical expressions that describe first-, second-, general-, and mixed-order kinetics as well as the recently developed semi-analytical expressions that derive from the one trap-one recombination center (OTOR) model that utilizes the Lambert W function or the Wright Omega function. We provide a comprehensive, flexible, convenient, and openly accessible program to analyze TL glow curves according to different models and expressions. The consistency of kinetic parameters determined using different model expressions was assessed using measured TL glow curve of CaF2:Dy.

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UNCERTAINTY OF THERMOLUMINESCENCE AT LOW DOSE LEVELS: A MONTE-CARLO SIMULATION STUDY.

Radiat Prot Dosimetry

December 2020

Ionizing Radiation Metrology Department, National Institute for Standards (NIS), Giza, Egypt.

The purpose of the current work is to investigate the effect of the scatter data and the background noise level on the uncertainty of the thermoluminescence (TL) measurements. The Monte-Carlo (MC) algorithm has been used to simulate the scattering data and the background noise signal in TL glow-curve. Under the simulation and experimental parameters used in the present study, a new general criterion for the minimum measurable dose has been established.

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We explore intrinsic thermal noise in soliton microcombs, revealing thermodynamic correlations induced by nonlinearity and group-velocity dispersion. A suitable dispersion design gives rise to control over thermal-noise transduction from the environment to a soliton microcomb. We present simulations with the Lugiato-Lefever equation (LLE), including temperature as a stochastic variable.

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The effects of the scattering data that might appear at the low radiation doses and the temperature lag that might occur between the heater pan and the detector on the thermoluminescence (TL) glow-curve have been addressed. The scattering data were mathematically induced in the TL glow curve using the Monte Carlo (MC) algorithm. While the phenomenon of the temperature lag has been simulated, assuming an exponential function.

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The structural relaxation in water solutions of kosmotrope (structure maker) and chaotrope (structure breaker) salts, namely sodium chloride, potassium chloride, and cesium chloride, were studied through quasielastic neutron scattering measurements. We found that the collective dynamics relaxation time at the structure factor peak obtained using heavy water solutions shows a distinctively different behavior in the kosmotrope as opposed to the chaotrope solutions, increasing with the salt concentration in the former and decreasing in the latter. In both cases the trends are proportional to the concentration dependence of the relative viscosity of the solutions.

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There is a need to understand the water dynamics of alkaline membrane fuel cells under various operating conditions to create electrodes that enable high performance and stable, long-term operation. Here we show, via operando neutron imaging and operando micro X-ray computed tomography, visualizations of the spatial and temporal distribution of liquid water in operating cells. We provide direct evidence for liquid water accumulation at the anode, which causes severe ionomer swelling and performance loss, as well as cell dryout from undesirably low water content in the cathode.

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Microresonator-based soliton frequency combs, microcombs, have recently emerged to offer low-noise, photonic-chip sources for applications, spanning from timekeeping to optical-frequency synthesis and ranging. Broad optical bandwidth, brightness, coherence, and frequency stability have made frequency combs important to directly probe atoms and molecules, especially in trace gas detection, multiphoton light-atom interactions, and spectroscopy in the extreme ultraviolet. Here, we explore direct microcomb atomic spectroscopy, using a cascaded, two-photon 1529-nm atomic transition in a rubidium micromachined cell.

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