Nanoparticles (NPs) typically display a wide distribution of different sizes in aquatic environments, yet little information is available on the impact of particle size dispersity on organismal uptake and elimination. This study investigated uptake and elimination of polyvinylpyrrolidone-coated platinum nanoparticles (PVP-PtNPs) of different sizes ( e.g. , 20.0 ± 4.8 nm, 40.5 ± 4.1 nm, and 70.8 ± 4.2 nm) by the estuarine amphipod Leptocheirus plumulosus . Accumulation and elimination were determined by measuring total Pt body burden in amphipods exposed to PtNPs using inductively coupled plasma-mass spectroscopy, as well as the mass and number PtNP body burden using single particle-ICP-MS (sp-ICP-MS). L. plumulosus accumulated Pt from PtNP suspensions of different sizes from water exposure, mostly ( e.g. , >90%) as PtNPs rather than as dissolved Pt. Mass- and number-based uptake increased with decreases in PtNP size whereas mass- and number-based elimination increased with increasing PtNP size. The residual whole-animal body burden of PtNPs after 48 h elimination increased with decreases in PtNP size, with residual body burdens approximately two-fold higher for amphipods exposed to 20 nm PtNPs than amphipods exposed to 70 nm PtNPs. PtNP influx rate ( k uw ) increased with decreasing NP size, with k uw s of 1.07 ± 0.31, 0.82 ± 0.22, and 0.67 ± 0.10 μg g −1 d −1 for 20 nm, 40 nm, and 70 nm PtNPs, respectively. PtNP efflux rate ( k e ) increased with increasing PtNP size, with k e s of 0.31 ± 0.08, 0.66 ± 0.04, and 0.83 ± 0.07 d −1 for 20 nm, 40 nm, and 70 nm PtNP, respectively. When exposed to mixtures of 40 and 70 nm PtNPs with equal masses, surface areas, or number concentrations of 40 nm and 70 nm PtNPs, L. plumulosus accumulated higher numbers of the 40 nm PtNPs than 70 nm PtNPs from all mixtures. The increased exposure concentration of 70 nm PtNPs in the mixture did not affect the uptake of 40 nm PtNPs, suggesting that in a polydispersed NP suspension the uptake of a given size fraction is independent of other size fractions in the mixture.
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Waveform-Agile Frequency Doubled Laser System for Optical Switching and Characterization of Phase Change Materials at Near-IR Wavelengths
We created a system for the characterization of Ge2Sb2Te5 starting with a 1550 nm CW laser and utilizing second harmonic generation through a PPLN crystal in order to achieve full pulse control at 775 nm.
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- Award ID(s):
- 1710273
- NSF-PAR ID:
- 10303770
- Date Published:
- Journal Name:
- Conference on Lasers and Electro-Optics
- Volume:
- 2020
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ABSTRACT Rigorous coupled wave analysis (RCWA) simulation was used to model the absorption in periodic arrays of GaAs(0.73)P(0.27) nanowires (NWs) on Si substrates dependent upon the diameter (D), length (L), and spacing (center-to-center distance, or pitch, P) of the NWs. Based on this study, two resonant arrangements for a top NW array sub-cell having the highest limiting short-circuit current densities (J_sc) were found to be close to D = 150 nm, P = 250 nm and D = 300 nm, P = 500 nm, both featuring the same packing density of 0.28. Even though a configuration with thinner NWs exhibited the highest J_sc = 19.46 mA/cm^2, the array with D = 350 nm and P = 500 nm provided current matching with the underlying Si sub-cell with J_sc = 18.59 mA/cm^2. Addition of a rear-side In(0.81)Ga(0.19)As nanowire array with D = 800 nm and P = 1000 nm was found to be suitable for current matching with the front NW sub-cell and middle Si. However, with thinner and sparser In(0.81)Ga(0.19)As NWs with D = 700 nm and P = 1000 nm, the J_scof the bottom sub-cell was increased from 17.35 mA/cm^2 to 18.76 mA/cm^2 using a planar metallic back surface reflector, thus achieving a current matching with the top and middle cells.more » « less
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Abstract The ongoing COVID-19 global pandemic has necessitated evaluating various disinfection technologies for reducing viral transmission in public settings. Ultraviolet (UV) radiation can inactivate pathogens and viruses but more insight is needed into the performance of different UV wavelengths and their applications. We observed greater than a 3-log reduction of SARS-CoV-2 infectivity with a dose of 12.5 mJ/cm 2 of 254 nm UV light when the viruses were suspended in PBS, while a dose of 25 mJ/cm 2 was necessary to achieve a similar reduction when they were in an EMEM culture medium containing 2%(v/v) FBS, highlighting the critical effect of media in which the virus is suspended, given that SARS-CoV-2 is always aerosolized when airborne or deposited on a surface. It was found that SARS-CoV-2 susceptibility (a measure of the effectiveness of the UV light) in a buffer such as PBS was 4.4-fold greater than that in a cell culture medium. Furthermore, we discovered the attenuation of UVC disinfection by amino acids, vitamins, and niacinamide, highlighting the importance of determining UVC dosages under a condition close to aerosols that wrap the viruses. We developed a disinfection model to determine the effect of the environment on UVC effectiveness with three different wavelengths, 222 nm, 254 nm, and 265 nm. An inverse correlation between the liquid absorbance and the viral susceptibility was observed. We found that 222 nm light was most effective at reducing viral infectivity in low absorbing liquids such as PBS, whereas 265 nm light was most effective in high absorbing liquids such as cell culture medium. Viral susceptibility was further decreased in N95 masks with 222 nm light being the most effective. The safety of 222 nm was also studied. We detected changes to the mechanical properties of the stratum corneum of human skins when the 222 nm accumulative exposure exceeded 50 J/cm 2 .The findings highlight the need to evaluate each UV for a given application, as well as limiting the dose to the lowest dose necessary to avoid unnecessary exposure to the public.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1364/CLEO_AT.2020.JTu2B.14
