Techn. Hochsch., Diss.--Aachen, 2007.

Zugl.: Berlin, Freie Univ., Diss., 2008

No description available.

Detection of airborne influenza virus is needed in order to determine exposure and prevent and control infections. Few researchers have successfully detected airborne influenza virus in environmental settings with current bioaerosol samplers. Therefore, new sampling strategies should be considered to increase the likelihood of detection. This study compared four bioaerosol samplers in collection of airborne influenza virus – the SKC Biosampler, NIOSH Biosampler, Andersen N6 single-stage impactor containing a liquid media, and the newly developed Next Generation Inhalable Aerosol Sampler (NGIAS). Ten 30-minute laboratory trials were completed by aerosolizing active influenza virus (H1N1) in a bioaerosol chamber to compare the ability of four bioaerosol samplers to collect aerosolized virus. Samples were analyzed using RT-qPCR. The mean total virus particles per liter of sampled air (TVP) recovered with the NGIAS was significantly less than that measured by all other samplers (p < 0.001). The TVP recovered with the SKC Biosampler (111.41) and Andersen N6 sampler (102.36) was substantially larger than that recovered with the NIOSH Biosampler (58.59), however the difference in TVP between these samplers was not statistically significant (SKC – NIOSH p-value = 0.187 ; Andersen – NIOSH p-value = 0.297). Our results demonstrated that liquid based bioaerosol samplers recovered more TVP than dry collection samplers. The high flow rate sampler, the Andersen N6, did not collect more TVP, but had a lower limit of detection than other samplers. Furthermore, the SKC Biosampler collected the most TVP. Therefore, future investigators should design a liquid based personal bioaerosol sampler to maximize the likelihood of influenza virus detection.

A circumferential slot In-line Virtual Impactor (IVI) has been designed using Computational Fluid Dynamics (CFD) simulation tools and experimentally characterized using monodispersed liquid aerosols to validate simulation results. The base design, IVI-100, has an application as a pre-separator for sampling inlets, where the device scalps large particles from the aerosol size distribution. The IVI-100 samples air in at 111 L/min and deliver the fine aerosol fraction in a 100 L/min flow and provide a cutpoint particle size of 10 µm, with a pressure drop of 45 Pa. An inverted dual cone configuration encased inside a tube provides the IVI-100 with a characteristic circumferential slot of width 0.254 mm (0.100 inches) and a slot length of 239 mm (9.42 inches) at the critical zone. The upper cone causes the flow to accelerate to an average throat velocity of 3.15 m/s, while the lower cone directs the major flow toward the exit port and minimizes recirculation zones that could cause flow instabilities in the major flow region. The cutpoint Stokes number is 0.73; however, the cutpoint can be adjusted by changing the geometrical spacing between the acceleration nozzle exit plane and a flow divider. Good agreement is obtained between numerically predicted and experimentally observed performance. An aerosol size selective inlet for bioaerosol and other air sampling applications using an upgraded prototype of IVI-100, mounted inside a BSI-100 inlet shell was tested in an aerosol wind tunnel over a speed range of 2 – 24 km/hr. The BSI-IVI-100 inlet has a cutpoint of 11 µm aerodynamic diameter and delivers the fine fraction at 100 L/m. The geometric standard deviation of the fractionation curve is 1.51 and the performance is not affected by wind speeds. An IVI-350, which is an adaptation of the IVI to be used as a powder fractionator, was designed based on computational simulations, and provides a cutpoint of 3 µm AD, while operating in a total flow rate of 350 L/min. Four Identical IVI -350 units will be operated in parallel to fractionate aerosolized powders in a 1400 L/min flow. An optimized inlet, with a contoured tear-drop shaped insert provides uniform flow to four identical IVI units and prevents powder accumulation in the system entrance.

In this study, a system for the collection of bioaerosols emitted from the mail sorting process was designed and characterized. Two different wetted-wall cyclones, the JBPDS cyclone and the glass cyclone sampler (GCS), were evaluated as system collection devices. These devices operate at 780 L/min and have a D50 of ~ 1 μm. A trimming impactor with a D50 of 10 μm was used upstream of the collection devices. Using two reference probes, the cyclone liquid outputs were compared with aerosol collected on filters and the output of an Aerosol-to-Hydrosol Transfer Stage (AHTS). The mass emission rate of the postal sorting machine was 3.15 mg/min and found not to vary significantly with flow rates above 700 L/min. On average, greater than 66% of the mass collected had a Da < 10 μm. Using a Coulter Counter, the volume median diameter (volume equivalent) for both device hydrosol outputs was 4.18 μm. For the effluent aerosol, the volume median diameter was 12.5 μm. For a bioaerosol release, this study found that greater than 65% (by volume) of the material released had a Da greater than 7.2 μm. Using filters, it was found that on average, 95% of the bioaerosol particles emitted had a Da less than 10 μm. According to the reference data, the expected number of bioaerosol particles in 1.5 times that collected by the GCS and 5.5 times that collected by the JBPDS cyclone for a one milligram release. The time constant for the system in response to a letter release was found to be 1.3 minutes for the GCS and 1.75 minutes for the JBPDS cyclone. A final note to this study states that the probe dimensions were incorrectly developed, therefore affecting the aspiration efficiency of the probes. In turn, this may have affected the outcome of some of the results. A plot is given at the end of the paper showing to what extent the results may have been affected. It is recommended that further experimental studies be performed to verify the results in this study.

Airborne disease transmission is a prominent problem facing an increasingly mobilized world. It involves small droplets (bioaerosols) containing pathogens which form in the lungs and are expelled to the environment, where they may persist in the air until inhaled by others. Conceptually, there are two basic approaches to preventing transmission: protect the potential target, or eliminate the source. To this end, the effectiveness of modifying mucus viscoelasticity, through cation exposure, to prevent pathogen transport via bioaerosols was investigated. In vitro models were developed to explore the proposed mechanisms for droplet formation: shear-induced surface-wave instabilities in the airway lining fluid (ALF) of the upper airways; and film formation during the re-opening of collapsed bronchioles in the lower airways. Droplet formation during tidal breathing was shown to be an inhalation process for both upper and lower airway models, and the bifurcation angle of the first bronchi was relevant to the upper airway model. A simulated cough system was also developed and produced the largest number of droplets. COPD sputum viscoelasticity was characterized and its response to cation presence measured: low concentrations of calcium resulted in increased complex modulus and decreased loss tangent (indicating increased fluid stiffness resulting from higher elasticity). Higher concentrations of calcium had the reverse effect. Using the cough system, calcium treated (low concentration) and untreated sputum were compared: treated sputum produced fewer droplets. Droplet concentration (number per liter of air) correlated well with the magnitude of the complex modulus. Once the reduction in total droplets was established, pathogen transport experiments, in which human rhinovirus (HRV) was added to calcium-treated and untreated COPD sputum, were performed. Cell culture media was exposed to cough-air from the samples and then placed on HRV-sensitized HeLa cells, which were then monitored for cell death. Cell death was observed for untreated sputum samples, but not for cation-treated samples, indicating that reducing bioaerosol formation (through cationic modification of mucus viscoelasticity) prevented airborne transport of the virus. / Engineering and Applied Sciences

Zugl.: Aachen, Techn. Hochsch., Diss., 2007

abstract: A new challenge on the horizon is to utilize the large amounts of protein found in the atmosphere to identify different organisms from which the protein originated. Included here is work investigating the presence of identifiable patterns of different proteins collected from the air and biological samples for the purposes of remote identification. Protein patterns were generated using high performance liquid chromatography (HPLC). Patterns created could identify high-traffic and low-traffic indoor spaces. Samples were collected from the air using air pumps to draw air through a filter paper trapping particulates, including large amounts of shed protein matter. In complimentary research aerosolized biological samples were collected from various ecosystems throughout Ecuador to explore the relationship between environmental setting and aerosolized protein concentrations. In order to further enhance protein separation and produce more detailed patterns for the identification of individual organisms of interest; a novel separation device was constructed and characterized. The separation device incorporates a longitudinal gradient as well as insulating dielectrophoretic features within a single channel. This design allows for the production of stronger local field gradients along a global gradient allowing particles to enter, initially transported through the channel by electrophoresis and electroosmosis, and to be isolated according to their characteristic physical properties, including charge, polarizability, deformability, surface charge mobility, dielectric features, and local capacitance. Thus, different types of particles are simultaneously separated at different points along the channel distance given small variations of properties. The device has shown the ability to separate analytes over a large dynamic range of size, from 20 nm to 1 &mu;m, roughly the size of proteins to the size of cells. In the study of different sized sulfate capped polystyrene particles were shown to be selectively captured as well as concentrating particles from 103 to 106 times. Qualitative capture and manipulation of &beta;-amyloid fibrils were also shown. The results demonstrate the selective focusing ability of the technique; and it may form the foundation for a versatile tool for separating complex mixtures. Combined this work shows promise for future identification of individual organisms from aerosolized protein as well as for applications in biomedical research. / Dissertation/Thesis / Ph.D. Chemistry 2011

abstract: Bioparticles comprise a diverse amount of materials ubiquitously present in nature. From proteins to aerosolized biological debris, bioparticles have important roles spanning from regulating cellular functions to possibly influencing global climate. Understanding their structures, functions, and properties provides the necessary tools to expand our fundamental knowledge of biological systems and exploit them for useful applications. In order to contribute to this efforts, the work presented in this dissertation focuses on the study of electrokinetic properties of liposomes and novel applications of bioaerosol analysis. Using immobilized lipid vesicles under the influence of modest (less than 100 V/cm) electric fields, a novel strategy for bionanotubule fabrication with superior throughput and simplicity was developed. Fluorescence and bright field microscopy was used to describe the formation of these bilayer-bound cylindrical structures, which have been previously identified in nature (playing crucial roles in intercellular communication) and made synthetically by direct mechanical manipulation of membranes. In the biological context, the results of this work suggest that mechanical electrostatic interaction may play a role in the shape and function of individual biological membranes and networks of membrane-bound structures. A second project involving liposomes focused on membrane potential measurements in vesicles containing trans-membrane pH gradients. These types of gradients consist of differential charge states in the lipid bilayer leaflets, which have been shown to greatly influence the efficacy of drug targeting and the treatment of diseases such as cancer. Here, these systems are qualitatively and quantitatively assessed by using voltage-sensitive membrane dyes and fluorescence spectroscopy. Bioaerosol studies involved exploring the feasibility of a fingerprinting technology based on current understanding of cellular debris in aerosols and arguments regarding sampling, sensitivity, separations and detection schemes of these debris. Aerosolized particles of cellular material and proteins emitted by humans, animals and plants can be considered information-rich packets that carry biochemical information specific to the living organisms present in the collection settings. These materials could potentially be exploited for identification purposes. Preliminary studies evaluated protein concentration trends in both indoor and outdoor locations. Results indicated that concentrations correlate to certain conditions of the collection environment (e.g. extent of human presence), supporting the idea that bioaerosol fingerprinting is possible. / Dissertation/Thesis / Ph.D. Chemistry 2011