Edgewood Chemical and Biological Center
Edgewood Chemical and Biological Center
Kesavan J.,Edgewood Chemical and Biological Center |
Kesavan M.,Johns Hopkins University
Aerosol Science and Technology | Year: 2017
Prevention of airborne contagious diseases depends on successful characterization of aerosols in the environment. The use of cascade impactors to characterize ambient aerosols is one of the most commonly used methods, providing data on both particle size and concentration. In this study, the use of a cascade impactor recently described in the literature using 8 mL of liquid in Petri dishes (CI-L) was compared with a new method that uses wet membrane filters on top of wax filled Petri dishes (CI-WWMF). Sampling efficiencies of the cascade impactors were evaluated using 0.5, 1, 3, and 5 μm polystyrene latex (PSL) microspheres and aerosol consisting of single spores of Bacillus atrophaeus var. globigii (BG). The sampling efficiency of the CI-L was 6%, 11%, 17%, 21%, and 58% for 0.5, 1, 3, 5 μm PSL microspheres and BG spores, respectively. Higher overall sampling efficiencies of 71%, 91%, 60%, 64%, and 104% were observed for the same size and type of particles for the CI-WWMF. This study indicates that using wet filters on top of wax-filled Petri dishes (CI-WWMF) in a viable cascade impactor is more efficient than the CI-L method for size-selectively collecting biological aerosols from the environment. The CI-WWMF method is useful when a liquid medium is required for identifying and quantifying organisms using polymerase chain reaction (PCR) and immuno-assay techniques. © 2017 American Association for Aerosol Research © 2017 American Association for Aerosol Research
Mirsafavi R.Y.,University of California at Santa Barbara |
Lai K.,University of California at Santa Barbara |
Kline N.D.,Edgewood Chemical and Biological Center |
Fountain A.W.,Edgewood Chemical and Biological Center |
And 2 more authors.
Analytical Chemistry | Year: 2017
Papaverine is a non-narcotic alkaloid found endemically and uniquely in the latex of the opium poppy. It is normally refined out of the opioids that the latex is typically collected for, hence its presence in a sample is strong prima facie evidence that the carrier from whom the sample was collected is implicated in the mass cultivation of poppies or the collection and handling of their latex. We describe an analysis technique combining surface-enhanced Raman spectroscopy (SERS) with microfluidics for detecting papaverine at low concentrations and show that its SERS spectrum has unique spectroscopic features that allows its detection at low concentrations among typical opioids. The analysis requires approximately 2.5 min from sample loading to results, which is compatible with field use. The weak acid properties of papaverine hydrochloride were investigated, and Raman bands belonging to the protonated and unprotonated forms of the isoquinoline ring of papaverine were identified. © 2017 American Chemical Society.
Kilianski A.,Edgewood Chemical and Biological Center
Journal of Virology | Year: 2014
Undergraduate, graduate, and postdoctoral scientists trained as virologists can play critical roles in public health, such as in health science policy, epidemiology, and national defense. Despite a need for basic science backgrounds within these fields, finding entry-level careers can be challenging. Volunteer opportunities are a great way for scientists to experience public health careers while still in school, and this article describes volunteering with the Medical Reserve Corps and outlines unique postgraduate opportunities for early-career virologists. © 2014, American Society for Microbiology.
Grant Glover T.,SAIC |
Peterson G.W.,Edgewood Chemical and Biological Center |
Schindler B.J.,SAIC |
Britt D.,University of California at Los Angeles |
Yaghi O.,University of California at Los Angeles
Chemical Engineering Science | Year: 2011
Metal organic framework (MOF-74) analogs have been synthesized using cobalt, magnesium, nickel, and zinc metal centers. The capability of these materials to remove ammonia, cyanogen chloride, and sulfur dioxide from air has been evaluated via fixed-bed breakthrough testing in both dry and humid conditions. Octane breakthrough tests were performed to determine the physisorption capacities of the materials. All materials were stored in air prior to use. Dynamic breakthrough capacities of the analogs were compared to 13X zeolite and BPL activated carbon. The impact of the metal center on the adsorption behavior is illustrated with each analog providing different ammonia and cyanogen chloride adsorption capacities. The results provide an important step in the assessment of the potential of MOFs to function as porous adsorbent materials. © 2010 Elsevier Ltd.
Clewes R.J.,UK Defence Science and Technology Laboratory |
Howle C.R.,UK Defence Science and Technology Laboratory |
Guicheteau J.,Edgewood Chemical and Biological Center |
Emge D.,Edgewood Chemical and Biological Center |
And 5 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013
The ability of a stand-off chemical detector to distinguish two different chemical warfare agents is demonstrated in this paper. Using Negative Contrast Imaging, based upon IR absorption spectroscopy, we were able to detect 1 μl of VX, sulfur mustard and water on a subset of representative surfaces. These experiments were performed at a range of 1.3 metres and an angle of 45° to the surface. The technique employed utilises a Q-switched intracavity MgO:PPLN crystal that generated 1.4 - 1.8 μm (shortwave) and 2.6 - 3.6 μm (midwave) infrared radiation (SWIR and MWIR, respectively). The MgO:PPLN crystal has a fanned grating design which, via translation through a 1064 nm pump beam, enables tuning through the SWIR and MWIR wavelength ranges. The SWIR and MWIR beams are guided across a scene via a pair of raster scanned mirrors allowing detection of absorption features within these spectral regions. This investigation exploited MWIR signatures, as they provided sufficient molecular information to distinguish between toxic and benign chemicals in these proof-of-concept experiments. ©2013 SPIE.
Swietnicki W.,Bethesda University |
Carmany D.,Batelle Memorial Institute |
Retford M.,Edgewood Chemical and Biological Center |
Guelta M.,Edgewood Chemical and Biological Center |
And 4 more authors.
PLoS ONE | Year: 2011
Yersinia pestis is a Gram negative zoonotic pathogen responsible for causing bubonic and pneumonic plague in humans. The pathogen uses a type III secretion system (T3SS) to deliver virulence factors directly from bacterium into host mammalian cells. The system contains a single ATPase, YscN, necessary for delivery of virulence factors. In this work, we show that deletion of the catalytic domain of the yscN gene in Y. pestis CO92 attenuated the strain over three million-fold in the Swiss-Webster mouse model of bubonic plague. The result validates the YscN protein as a therapeutic target for plague. The catalytic domain of the YscN protein was made using recombinant methods and its ATPase activity was characterized in vitro. To identify candidate therapeutics, we tested computationally selected small molecules for inhibition of YscN ATPase activity. The best inhibitors had measured IC50 values below 20 μM in an in vitro ATPase assay and were also found to inhibit the homologous BsaS protein from Burkholderia mallei animal-like T3SS at similar concentrations. Moreover, the compounds fully inhibited YopE secretion by attenuated Y. pestis in a bacterial cell culture and mammalian cells at μM concentrations. The data demonstrate the feasibility of targeting and inhibiting a critical protein transport ATPase of a bacterial virulence system. It is likely the same strategy could be applied to many other common human pathogens using type III secretion system, including enteropathogenic E. coli, Shigella flexneri, Salmonella typhimurium, and Burkholderia mallei/pseudomallei species.
Sullenberger R.M.,Lincoln Laboratory |
Clark M.L.,Lincoln Laboratory |
Kunz R.R.,Lincoln Laboratory |
Samuels A.C.,Edgewood Chemical and Biological Center |
And 3 more authors.
Optics Express | Year: 2014
Dynamic photoacoustic spectroscopy (DPAS) is a high sensitivity technique for standoff detection of trace vapors. A field-portable DPAS system has potential as an early warning provider for gaseous-based chemical threats. For the first time, we utilize DPAS to successfully detect the presence of trace aerosols. Aerosol identification via long-wavelength infrared (LWIR) spectra is demonstrated. We estimate the sensitivity of our DPAS system to aerosols comprised of silica particles is comparable to that of SF6 gas based on a signal level per absorbance unit metric for the two materials. The implications of these measurements are discussed. © 2014 Optical Society of America.
Robertson J.,Curtin University Australia |
Levy A.,Hospital Avenue |
Sagripanti J.-L.,Edgewood Chemical and Biological Center |
Inglis T.J.J.,Hospital Avenue
American Journal of Tropical Medicine and Hygiene | Year: 2010
We studied the effect of environmental parameters on the survival of Burkholderia pseudomallei. There was a small increase in bacterial count for up to 28 days in sterilized distilled water or rain water, in water at 20°C or 40°C, and in buffered solutions of pH 4 or higher. Counts of culturable B. pseudomallei declined at pH 3, in the presence of seawater or water with concentrations of 4% salt or higher, and under refrigeration. The morphological appearances of B. pseudomallei changed under conditions that maintained culturable numbers from bacilli to coccoid cells and spiral forms under pH or salt stress. These observations indicate that B. pseudomallei can endure nutrient-depleted environments as well as a wide range of pH, salt concentrations, and temperatures for periods of up to 28 days. The relative stability of B. pseudomallei under these conditions underlines the tenacity of this species and its potential for natural dispersal in water: in surface water collections, in managed water distribution systems, and through rainfall. These survival properties help explain the recent expansion of the known melioidosis endemic zone in Australia and may have played a part in recent melioidosis outbreaks. Copyright © 2010 by The American Society of Tropical Medicine and Hygiene.
Blatny J.,FFI Fotsvarets |
Fountain III A.W.,Edgewood Chemical and Biological Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011
To provide useful information during military operations, or as part of other security situations, a biological aerosol detector has to respond within seconds or minutes to an attack by virulent biological agents, and with low false alarms. Within this time frame, measuring virulence of a known microorganism is extremely difficult, especially if the microorganism is of unknown antigenic or nucleic acid properties. Measuring "live" characteristics of an organism directly is not generally an option, yet only viable organisms are potentially infectious. Fluorescence based instruments have been designed to optically determine if aerosol particles have viability characteristics. Still, such commercially available biological aerosol detection equipment needs to be improved for their use in military and civil applications. Air has an endogenous population of microorganisms that may interfere with alarm software technologies. To design robust algorithms, a comprehensive knowledge of the airborne biological background content is essential. For this reason, there is a need to study ambient live bacterial populations in as many locations as possible. Doing so will permit collection of data to define diverse biological characteristics that in turn can be used to fine tune alarm algorithms. To avoid false alarms, improving software technologies for biological detectors is a crucial feature requiring considerations of various parameters that can be applied to suppress alarm triggers. This NATO Task Group will aim for developing reference methods for monitoring biological aerosol characteristics to improve alarm algorithms for biological detection. Additionally, they will focus on developing reference standard methodology for monitoring biological aerosol characteristics to reduce false alarm rates. © 2011 SPIE.
Staymates M.,U.S. National Institute of Standards and Technology |
Bottiger J.,Edgewood Chemical and Biological Center |
Schepers D.,Edgewood Chemical and Biological Center |
Staymates J.,U.S. National Institute of Standards and Technology
Aerosol Science and Technology | Year: 2013
The design and characterization of a streamlined, high-volume particle impactor intended for use with trace chemical analysis is presented. The impactor has a single round jet and is designed to operate at a flow rate of 1000 L/min. Computational fluid dynamics (CFD) was used as a tool to optimize the aerodynamic performance of the impactor by iteratively redesigning the geometry and curvature of the internal walls. By eliminating recirculation zones within the flowfield of the impactor and using flowfield streamlines as new walls, successive designs revealed a significant reduction in the pressure drop across the impactor. Particle trajectories were simulated in the impactor and the 50% cutpoint was determined to be 1.05 μm. The impaction surface itself is easily removed fromthe body of the impactor assembly, potentially facilitating rapid trace chemical analysis using a variety of chemical detection techniques. A prototype impactor was fabricated with a 3D rapid prototyping printer and characterized in terms of particle cut-off diameter using test aerosols generated by an Ink Jet Aerosol Generator (IJAG) and fluorescence intensity measurements. The experimental particle cut-off diameter was not able to be measured because the smallest aerosol particles that could be tested were 1.86 μm which were collected at 100% efficiency. Particulate contamination from the high-explosive compound C4 was also collected with the impactor to demonstrate operational utility for trace explosives detection. Copyright © American Association for Aerosol Research.