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Opt Express ; 27(23): 33061-33069, 2019 Nov 11.
Artículo en Inglés | MEDLINE | ID: mdl-31878380


We present an advanced optical-trapping method that is capable of trapping arbitrary shapes of transparent and absorbing particles in air. Two parabolic reflectors were used to reflect the inner and outer parts of a single hollow laser beam, respectively, to form two counter-propagating conical beams and bring them into a focal point for trapping. This novel design demonstrated high trapping efficiency and strong trapping robustness with a simple optical configuration. Instead of using expensive microscope objectives, the parabolic reflectors can not only achieved large numerical aperture (N.A.) focusing, but were also able to focus the beam far away from optical surfaces to minimize optics contamination. This design also offered a large free space for flexible integration with other measuring techniques, such as optical-trapping Raman spectroscopy, for on-line single particle characterization.

Air Med J ; 38(5): 359-365, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31578975


INTRODUCTION: Aeromedical evacuation (AE) is a challenging process, further complicated when a patient has a highly hazardous communicable disease (HHCD). We conducted a review of the literature to evaluate the processes and procedures utilized for safe AE high-level containment transport (AE-HLCT) of patients with HHCDs. METHODS: A literature search was performed in PubMed/MEDLINE (from 1966 through January 2019). Authors screened abstracts for inclusion criteria and full articles were reviewed if the abstract was deemed to contain information related to the aim. RESULTS: Our search criteria yielded 14 publications and were separated based upon publication dates, with the natural break point being the beginning of the 2013-2016 Ebola virus disease epidemic. Best practices and recommendations from identified articles are subdivided into pre-flight preparations, inflight operations, and post-flight procedures. CONCLUSIONS: Limited peer-reviewed literature exists on AE-HLCT, including important aspects related to healthcare worker fatigue, alertness, shift scheduling, and clinical care performance. This hinders the sharing of best practices to inform evacuations and equip teams for future outbreaks. Despite the successful use of different aircraft and technologies, the unique nature of the mission opens the opportunity for greater coordination and development of consensus standards for AE-HLCT operations.

Appl Opt ; 56(3): B1-B4, 2017 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-28157859


We demonstrate a method for measuring elastic back-scattering patterns from single laser trapped micron-sized particles, spanning the scattering angle range of θ=167.7°-180° and φ=0°-360° in spherical coordinates. We calibrated the apparatus by capturing light-scattering patterns of 10 µm diameter borosilicate glass microspheres and comparing their scattered intensities with Lorenz-Mie theory. Back-scattering patterns are also presented from a single trapped Johnson grass spore, two attached Johnson grass spores, and a cluster of Johnson grass spores. The method has potential use in characterizing airborne aerosol particles, and may be used to provide back-scattering data for lidar applications.

Opt Express ; 22(7): 8165-89, 2014 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-24718194


A system for measuring spectrally-resolved fluorescence cross sections of single bioaerosol particles has been developed and employed in a biological safety level 3 (BSL-3) facility at Edgewood Chemical and Biological Center (ECBC). It is used to aerosolize the slurry or solution of live agents and surrogates into dried micron-size particles, and to measure the fluorescence spectra and sizes of the particles one at a time. Spectrally-resolved fluorescence cross sections were measured for (1) bacterial spores: Bacillus anthracis Ames (BaA), B. atrophaeus var. globigii (BG) (formerly known as Bacillus globigii), B. thuringiensis israelensis (Bti), B. thuringiensis kurstaki (Btk), B. anthracis Sterne (BaS); (2) vegetative bacteria: Escherichia coli (E. coli), Pantoea agglomerans (Eh) (formerly known as Erwinia herbicola), Yersinia rohdei (Yr), Yersinia pestis CO92 (Yp); and (3) virus preparations: Venezuelan equine encephalitis TC83 (VEE) and the bacteriophage MS2. The excitation wavelengths were 266 nm, 273 nm, 280 nm, 365 nm and 405 nm.

Bacterias/química , Factores Biológicos/análisis , Espectrometría de Fluorescencia/métodos , Fluorescencia
Opt Express ; 21(19): 22285-313, 2013 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-24104120


This paper describes a mathematical model of fluorescent biological particles composed of bacteria, viruses, or proteins. The fluorescent and/or light absorbing molecules included in the model are amino acids (tryptophan, etc.); nucleic acids (DNA, RNA, etc.); coenzymes (nicotinamide adenine dinucleotides, flavins, and vitamins B6 and K and variants of these); and dipicolinates. The concentrations, absorptivities, and fluorescence quantum yields are estimated from the literature, often with large uncertainties. The bioparticles in the model are spherical and homogeneous. Calculated fluorescence cross sections for particles excited at 266, 280, and 355 nm are compared with measured values from the literature for several bacteria, bacterial spores and albumins. The calculated 266- and 280-nm excited fluorescence is within a factor of 3.2 of the measurements for the vegetative cells and proteins, but overestimates the fluorescence of spores by a factor of 10 or more. This is the first reported modeling of the fluorescence of bioaerosols in which the primary fluorophores and absorbing molecules are included.

Aerosoles/metabolismo , Bacterias/metabolismo , Biopolímeros/química , Modelos Biológicos , Espectrometría de Fluorescencia/métodos , Absorción , Aerosoles/química , Bacterias/química , Simulación por Computador , Fluorescencia , Luz , Modelos Químicos
Opt Express ; 20(28): 29867-81, 2012 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-23388813


A laboratory system for exposing aerosol particles to ozone and rapidly measuring the subsequent changes in their single-particle fluorescence is reported. The system consists of a rotating drum chamber and a single-particle fluorescence spectrometer (SPFS) utilizing excitation at 263 nm. Measurements made with this system show preliminary results on the ultra-violet laser-induced-fluorescence (UV-LIF) spectra of single aerosolized particles of Yersinia rohdei, and of MS2 (bacteriophage) exposed to ozone. When bioparticles are exposed in the chamber the fluorescence emission peak around 330 nm: i) decreases in intensity relative to that of the 400-550 nm band; and ii) shifts slightly toward shorter-wavelengths (consistent with further drying of the particles). In these experiments, changes were observed at exposures below the US Environmental Protection Agency (EPA) limits for ozone.

Aerosoles/análisis , Atmósfera/química , Laboratorios , Levivirus/química , Ozono/química , Yersinia/química , Espectrometría de Fluorescencia