scholarly journals Effect of gamma irradiation on filtering facepiece respirators and SARS-CoV-2 detection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Khaled Al-Hadyan ◽  
Ghazi Alsbeih ◽  
Najla Al-Harbi ◽  
Sara Bin Judia ◽  
Maha Al-Ghamdi ◽  
...  
Keyword(s):  
Particle Size ◽  
Gamma Irradiation ◽  
Filtration Efficiency ◽  
Particle Sizes ◽  
Threshold Values ◽  
Dose Rates ◽  
Size Dependent ◽  
High Doses ◽  
Rna Genes ◽  
Potential Use

AbstractTo cope with the shortage of filtering facepiece respirators (FFRs) during the coronavirus (COVID-19) pandemic, healthcare institutions were forced to reuse FFRs after applying different decontamination methods including gamma-irradiation (GIR). The aim of this study was to evaluate the effect of GIR on the filtration efficiency (FE) of FFRs and on SARS-CoV-2 detection. The FE of 2 FFRs types (KN95 and N95-3 M masks) was assessed at different particle sizes (0.3–5 µm) following GIR (0–15 kGy) delivered at either typical (1.65 kGy/h) or low (0.5088 kGy/h) dose rates. The detection of two SARS-CoV-2 RNA genes (E and RdRp4) following GIR (0–50 kGy) was carried out using RT-qPCR assay. Both masks showed an overall significant (P < 0.001) reduction in FE with increased GIR doses. No significant differences were observed between GIR dose rates on FE. The GIR exhibited significant increases (P ≤ 0.001) in the cycle threshold values (ΔCt) of both genes, with no detection following high doses. In conclusion, complete degradation of SARS-CoV-2 RNA can be achieved by high GIR (≥ 30 kGy), suggesting its potential use in FFRs decontamination. However, GIR exhibited adverse effects on FE in dose- and particle size-dependent manners, rendering its use to decontaminate FFRs debatable.

Multiscale Analysis of Particle Size-dependent Steady Compaction Waves in Granular Energetic Materials

2012 ◽  
Vol 13 (2) ◽  
Author(s):  
Xin-Ming Zhang ◽  
Yan-Qing Wu ◽  
Feng-Lei Huang
Keyword(s):  
Particle Size ◽  
Energetic Materials ◽  
Multiscale Analysis ◽  
Multiscale Model ◽  
Particle Sizes ◽  
Coarse Particles ◽  
Size Dependent ◽  
Compaction Processes ◽  
Compaction Waves

AbstractA multiscale model is used to analyze the compaction processes in granular HMX beds composed of different particle sizes (coarse particles,

The Heating Effects of Dextran Coated Iron Oxides

2006 ◽  
Vol 962 ◽  
Author(s):  
Qi Zeng ◽  
Ian Baker ◽  
Jack Hoopes
Keyword(s):  
Particle Size ◽  
Specific Absorption Rate ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Particle Sizes ◽  
Heating Effects ◽  
Magnetic Hysteresis Loops ◽  
Heating Behavior ◽  
Potential Use

ABSTRACTThe structural and quasi-static magnetic behaviors and the temperature rises of three Dextran-coated maghemite nanoparticles subjected to alternating magnetic field (AMF) were investigated for potential use in magnetic hyperthermia treatments. In order to elucidate the effect of the hydrodynamic particle size on the specific absorption rate, the temperature rises for various hydrodynamic particle sizes were investigated in AMFs of various strengths and frequencies. Structural characterization was performed using a TEM and a SEM as well as by dynamic light scattering, and the quasi-static magnetic hysteresis loops were measured using a VSM. The heating behavior is discussed in relation to the magnetic behavior and particle size. While it was found that the heating mechanism for the ferromagnetic particles was mainly magnetic hysteresis losses, Brownian relaxation losses also contributed to the heating.

SIZE-DEPENDENT EQUATION OF STATE FOR NANOMATERIALS

2012 ◽  
Vol 11 (01) ◽  
pp. 1250010
Author(s):  
ARCHANA BHATT ◽  
MUNISH KUMAR
Keyword(s):  
Particle Size ◽  
Equation Of State ◽  
Size Dependence ◽  
Theoretical Method ◽  
Particle Sizes ◽  
Isothermal Compression ◽  
Compression Curve ◽  
Size Dependent ◽  
Theory And Experiment ◽  
Good Agreement

Simple theoretical method is developed to study the size dependence of equation of state of nanomaterials. The isothermal compression of Ni and ε- Fe has been computed for different particle sizes. A shift in compression curve is obtained by increasing the particle size. This demonstrates the softening of the material by increasing the particle size. For larger particle size (~100 nm) the compression curve resembles with that of the bulk. This demonstrates that the nanomaterial becomes bulk for larger particle size. The results have been compared with the available experimental data. A good agreement between theory and experiment demonstrates the validity of the method proposed in the present paper.

scholarly journals Dynamic restructuring of supported metal nanoparticles and its implications for structure insensitive catalysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Charlotte Vogt ◽  
Florian Meirer ◽  
Matteo Monai ◽  
Esther Groeneveld ◽  
Davide Ferri ◽  
...  
Keyword(s):  
Particle Size ◽  
Metal Nanoparticles ◽  
Carbon Diffusion ◽  
Hydrogenation Reaction ◽  
Particle Sizes ◽  
Empirical Observation ◽  
Size Dependent ◽  
Ethene Hydrogenation ◽  
Structure Sensitive ◽  
Supported Metal Nanoparticles

AbstractSome fundamental concepts of catalysis are not fully explained but are of paramount importance for the development of improved catalysts. An example is the concept of structure insensitive reactions, where surface-normalized activity does not change with catalyst metal particle size. Here we explore this concept and its relation to surface reconstruction on a set of silica-supported Ni metal nanoparticles (mean particle sizes 1–6 nm) by spectroscopically discerning a structure sensitive (CO2 hydrogenation) from a structure insensitive (ethene hydrogenation) reaction. Using state-of-the-art techniques, inter alia in-situ STEM, and quick-X-ray absorption spectroscopy with sub-second time resolution, we have observed particle-size-dependent effects like restructuring which increases with increasing particle size, and faster restructuring for larger particle sizes during ethene hydrogenation while for CO2 no such restructuring effects were observed. Furthermore, a degree of restructuring is irreversible, and we also show that the rate of carbon diffusion on, and into nanoparticles increases with particle size. We finally show that these particle size-dependent effects induced by ethene hydrogenation, can make a structure sensitive reaction (CO2 hydrogenation), structure insensitive. We thus postulate that structure insensitive reactions are actually apparently structure insensitive, which changes our fundamental understanding of the empirical observation of structure insensitivity.

Size-Dependent Thermodynamic Properties of the Reaction of Nano-ZnO with Benzoic Acid

NANO ◽  
2015 ◽  
Vol 10 (07) ◽  
pp. 1550104 ◽  
Author(s):  
Shuting Wang ◽  
Zixiang Cui ◽  
Yongqiang Xue
Keyword(s):  
Particle Size ◽  
Thermodynamic Properties ◽  
Benzoic Acid ◽  
Equilibrium Constant ◽  
Particle Diameter ◽  
Particle Sizes ◽  
Research System ◽  
Reaction Enthalpy ◽  
Nano Zno ◽  
Size Dependent

Studying the thermodynamic properties of the reaction of nanoparticle with organic substance is significant for the application of nanomaterial in organic fields. In this work, by using the reaction of nano- ZnO with different particle sizes with benzoic acid as a research system, the size-dependent standard equilibrium constant and reaction thermodynamic properties were analyzed theoretically, and the influence regularities of the particle size on the standard equilibrium constant and the reaction thermodynamic properties were studied. The excellent agreement between the experimental results and theoretical analysis shows that the particle size has remarkable influence on the standard equilibrium constant and the thermodynamic properties of the reaction; with the decrease of the particle size, the standard equilibrium constant increases, while the standard molar reaction Gibbs energy, the standard molar reaction enthalpy and the standard molar reaction entropy decrease. Furthermore, the logarithm of the standard equilibrium constant and the thermodynamic properties present linear relations with the reciprocal of the particle diameter, respectively. The theory and the influence regularities will provide useful tools to lead better and broader application of nanomaterial in organic fields.

Multiscale Analysis of Particle Size-dependent Steady Compaction Waves in Granular Energetic Materials

2012 ◽  
Vol 13 (2) ◽  
Author(s):  
Xin-Ming Zhang ◽  
Yan-Qing Wu ◽  
Feng-Lei Huang
Keyword(s):  
Particle Size ◽  
Energetic Materials ◽  
Multiscale Analysis ◽  
Multiscale Model ◽  
Particle Sizes ◽  
Coarse Particles ◽  
Size Dependent ◽  
Compaction Processes ◽  
Compaction Waves

AbstractA multiscale model is used to analyze the compaction processes in granular HMX beds composed of different particle sizes (coarse particles,

Particle Size Dependent Structural and Magnetic Properties of CoCrFeO4 Nanoparticles

2012 ◽  
Vol 486 ◽  
pp. 129-133
Author(s):  
R. Mane Dhanraj ◽  
H. Kadam Ram ◽  
T. Alone Suresh ◽  
E. Shirsath Sagar
Keyword(s):  
Particle Size ◽  
Sintering Temperature ◽  
Sol Gel ◽  
Combustion Method ◽  
Blocking Temperature ◽  
Particle Sizes ◽  
Particle Size Range ◽  
Size Dependent ◽  
Auto Combustion ◽  
Different Temperatures

Nanoparticles of CoCrFeO4ferrite in the particle size range of 9 - 38 nm have been prepared by a sol-gel auto combustion method. Synthesized powders were annealed at four different temperatures viz. 400 °C, 600 °C, 800 °C and 1000 °C. Particle sizes are determined by X-ray analysis and TEM. The size of the nanoparticles increase linearly with sintering temperature and time, most probably due to coalescence that increases as sintering temperature increases. The saturation magnetization increases from 62 to 81 emu/g and coercivity initially increases up to 814 Oe and then decreases to 366 Oe with increase in particle size and sintering temperature. The typical blocking temperature increases from 135 to 165 K with increasing particle size.

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