The charge distribution of airborne MS2 bacteriophage nanoparticles and the efficiency of electrical-mobility-based capture mechanisms with bipolar charging were studied. MS2 virions form large ...agglomerated particles in a suspension. The average charge on airborne MS2 virions can be as high as one unit charge (negatively charged). The application of both soft X-ray irradiation and alpha rays from a Po-210 bipolar charger was shown to not only reduce the average charge on MS2 virion particles but also partially fragment the larger MS2 virion agglomerates, thereby increasing the number of ultrafine MS2 virion particles. A cylindrical electrostatic precipitator with a mounted soft X-ray emitter was used to determine the effectiveness of electrical capture methods for virus particles. At low applied voltages, it was found that the capture efficiency of ultrafine virus particles can be increased by applying in situ soft X-ray irradiation with electrostatic precipitation. It has also been shown that in the presence of both a positive and negative corona, virus particles are readily captured with log removal values exceeding 4. The unit developed and demonstrated in this work is a compact, low-pressure drop system that can be readily mounted in ventilation ducts or air supply systems to remove ultrafine particles such as viruses.
Protein binding and protein-induced nanoparticle aggregation are known to occur for a variety of nanomaterials, with the extent of binding and aggregation highly dependent on nanoparticle surface ...properties. However, often lacking are techniques that enable quantification of the extent of protein binding and aggregation, particularly for nanoparticles with polydisperse size distributions. In this study, we adapt ion mobility spectrometry (IMS) to examine the binding of bovine serum albumin to commercially available anionic-surfactant-coated superparamagnetic iron oxide nanoparticles (SPIONs), which are initially ∼21 nm in mean mobility diameter and have a polydisperse size distribution function (geometric standard deviation near 1.4). IMS, carried out with a hydrosol-to-aerosol converting nebulizer, a differential mobility analyzer, and a condensation particle counter, enables measurements of SPION size distribution functions for varying BSA/SPION number concentration ratios. IMS measurements suggest that initially (at BSA concentrations below 50 nM) BSA binds reversibly to SPION surfaces with a binding site density in the 0.05–0.08 nm–2 range. However, at higher BSA concentrations, BSA induces SPION–SPION aggregation, evidenced by larger shifts in SPION size distribution functions (mean diameters beyond 40 nm for BSA concentrations near 100 nM) and geometric standard deviations (near 1.3) consistent with self-preserving aggregation theories. The onset of BSA aggregation is correlated with a modest but statistically significant decrease in the specific absorption rate (SAR) of SPIONs placed within an alternating magnetic field. The coating of SPIONs with mesoporous silica (MS-SPIONs) as well as PEGylation (MS-SPIONs-PEG) is found to completely mitigate BSA binding and BSA-induced aggregation; IMS-inferred size distribution functions are insensitive to BSA concentration for MS-SPIONs and MS-SPIONs-PEG. The SARs of MS-SPIONs are additionally insensitive to BSA concentration, confirming the SAR decrease is linked to BSA-induced aggregation.
The Fourth Data Release of the Sloan Digital Sky Survey Adelman-McCarthy, Jennifer K; Allam, Sahar S; Anderson, Kurt S. J ...
The Astrophysical journal. Supplement series,
01/2006, Letnik:
162, Številka:
1
Journal Article
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This paper describes the Fourth Data Release of the Sloan Digital Sky Survey (SDSS), including all survey-quality data taken through 2004 June. The data release includes five-band photometric data ...for 180 million objects selected over 6670 deg super(2) and 673,280 spectra of galaxies, quasars, and stars selected from 4783 deg super(2) of those imaging data using the standard SDSS target selection algorithms. These numbers represent a roughly 27% increment over those of the Third Data Release; all the data from previous data releases are included in the present release. The Fourth Data Release also includes an additional 131,840 spectra of objects selected using a variety of alternative algorithms, to address scientific issues ranging from the kinematics of stars in the Milky Way thick disk to populations of faint galaxies and quasars.
The ability to analyze and identify large macromolecular complexes whose molecular weight is beyond the analyzable range of mass spectrometry is of great interest. The size of such complexes makes ...them suitable for analysis via mobility size spectrometry. In this work, charge reduced electrospray size spectrometry was used for the analysis of bacteriophage viruses with total molecular masses ranging from 3.6 MDa up to the gigadalton range. The electrospray source used was operated in “cone jet” mode with a mean droplet diameter of 170.56 nm. Bacteriophage MS2 was found to have a mobility diameter of 24.13 ± 0.06 nm and remain highly viable after the electrospray process. Larger bacteriophages T2 and T4 have lengths greater than the diameter of the electrospray jet and droplets; thus, they could not be completely enclosed and were found to fragment at the virus capsid head−tail noncovalent interface during either the jet formation or jet breakup process. No viable T2 or T4 virions were detectable after being electrosprayed. While the exact mechanism of fragmentation could not be determined, it is proposed here that macromolecular fragmentation at noncovalent interfaces occurs due to mechanically and electrically induced stresses during jet formation and jet breakup. Bacteriophage T4 capsid heads were found to be statistically significantly larger than bacteriophage T2 capsid heads, with a mean peak diameter of 88.32 ± 1.02 nm for T4 and 87.03 ± 0.18 nm for T2. While capsid head fragments were detectable, tail and tail-fiber fragments could not be detected by size spectrometric analysis. This is attributed to the fact that the contractile tails of bacteriophage T2 and T4 virions mechanically deform to a varying degree while confined within the smaller jet and droplets. Further evidence of contractile tail deformation during the electrospray process was found by measuring the size spectrum of bacteriophage λ, which has a noncontractile tail. Bacteriophage λ had two distinct peaks in its size spectrum, one corresponding to the capsid head and the other corresponding to the tail fragment. Size spectrometry was also used for rapid quantification of virus concentrations, thus demonstrating its full capabilities in the analysis of large macromolecular complexes.
Loxosceles spiders have a worldwide distribution and are considered one of the most medically important groups of spiders. Envenomation (loxoscelism) can result in dermonecrosis and, less commonly, a ...systemic illness that can be fatal. The mechanism of venom action is multifactorial and incompletely understood. The characteristic dermonecrotic lesion results from the direct effects of the venom on the cellular and basal membrane components, as well as the extracellular matrix. The initial interaction between the venom and tissues causes complement activation, migration of polymorphic neutrophils, liberation of proteolytic enzymes, cytokine and chemokine release, platelet aggregation, and blood flow alterations that result in edema and ischemia, with development of necrosis. There is no definitive treatment for loxoscelism. However, animal model studies suggest the potential value of specific antivenom to decrease lesion size and limit systemic illness even when such administration is delayed.
Aims: The aerosolization and collection of submicrometre and ultrafine virus particles were studied with the objective of developing robust and accurate methodologies to study airborne viruses.
...Methods and Results: The collection efficiencies of three sampling devices used to sample airborne biological particles – the All Glass Impinger 30, the SKC BioSampler® and a frit bubbler – were evaluated for submicrometre and ultrafine virus particles. Test virus aerosol particles were produced by atomizing suspensions of single‐stranded RNA and double‐stranded DNA bacteriophages. Size distribution results show that the fraction of viruses present in typical aqueous virus suspensions is extremely low such that the presence of viruses has little effect on the particle size distribution of atomized suspensions. It has been found that none of the tested samplers are adequate in collecting submicrometre and ultrafine virus particles, with collection efficiencies for all samplers below 10% in the 30–100 nm size range. Plaque assays and particle counting measurements showed that all tested samplers have time‐varying virus particle collection efficiencies. A method to determine the size distribution function of viable virus containing particles utilizing differential mobility selection was also developed.
Conclusions: A combination of differential mobility analysis and traditional plaque assay techniques can be used to fully characterize airborne viruses.
Significance and Impact of the Study: The data and methods presented here provide a fundamental basis for future studies of submicrometre and ultrafine airborne virus particles.
Sloan Digital Sky Survey: Early Data Release Lupton, Robert H; Bernardi, Mariangela; Castander, Francisco J ...
The Astronomical journal,
01/2002, Letnik:
123, Številka:
1
Journal Article
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