Portable automatic bioaerosol sampling system for rapid on-site detection of targeted airborne microorganisms

Bioaerosols could cause various severe human and animal diseases and their opportune and qualitative precise detection and control is becoming a significant scientific and technological topic for consideration. Over the last few decades bioaerosol detection has become an important bio-defense related issue. Many types of portable and stationary bioaerosol samplers have been developed and, in some cases, integrated into automated detection systems utilizing various microbiological techniques for analysis of collected microbes. This paper describes a personal sampler used in conjunction with a portable real-time PCR technique. It was found that a single fluorescent dye could be successfully used in multiplex format for qualitative detection of numerous targeted bioaerosols in one PCR tube making the suggested technology a reliable "first alert" device. This approach has been specifically developed and successfully verified for rapid detection of targeted microorganisms by portable PCR devices, which is especially important under field conditions, where the number of microorganisms of interest usually exceeds the number of available PCR reaction tubes. The approach allows detecting targeted microorganisms and triggering some corresponding sanitary and quarantine procedures to localize possible spread of dangerous infections. Following detailed analysis of the sample under controlled laboratory conditions could be used to exactly identify which particular microorganism out of a targeted group has been rapidly detected in the field. It was also found that the personal sampler has a collection efficiency higher than 90% even for small-sized viruses (>20 nm) and stable performance over extended operating periods. In addition, it was found that for microorganisms used in this project (bacteriophages MS2 and T4) elimination of nucleic acids isolation and purification steps during sample preparation does not lead to the system sensitivity reduction, which is extremely important for development of miniature bioaerosol monitoring instrumentation in the future. © 2012 The Royal Society of Chemistry

Study of Emission Rates from Fluidized Catalytic Crackers During Start Up Situations

Fluidized Catalytic Cracker Units (FCCU) have been used for many years in the oil refining industry. Under normal operation, there is little concern regarding catalyst dust emission into the atmosphere from these devices. However, concern does arise during FCCU start ups, as higher than normal emission rates are common. Stack sampling was carried out on an FCCU during start up to confirm the magnitude and type of emissions present. The current paper presents the results of stack testing undertaken during the first 19 days after a start up and discusses distinct stages, with regards to air emissions, which occur during that period of time

Surface plasmon resonance-based bacterial aerosol detection

Aims: In the area of bioaerosol research, rapid methods for precise detection attracted much interest over last decades. One of such technologies operating in nearly real-time mode without any specific labelling is known as surface plasmon resonance (SPR). Recently, we validated a SPR protocol in conjunction with our earlier developed personal bioaerosol sampler for rapid detection of airborne viruses. Considering that the biological interaction between targeted micro-organism and corresponding antibody is strongly related to sizes of targeted micro-organisms, this research is vital validating suitability of SPR technique for bacterial aerosol detection, as characteristic size of bacteria is 2-3 orders of magnitude larger than sizes of common viruses. The combination of SPR with portable air sampling instrumentation could lead to the development of portable bioaerosol monitor. Methods and Results: This study is focussed on the SPR technology application for direct detection of common environmental bacterial strain-Escherichia coli. The detection limit of developed SPR techniques based on utilization of a planar gold sensor chip functionalized with polyclonal antibody via NeutrAvidin junction for sensing of bacterial cells was found to be 1·5 × 103 CFU ml-1, which corresponds to the limit of detection in the air to be 2·19 × 104 CFU l-1 for 1 min of sampling time. Conclusions: The technology was found fully suitable for rapid and reliable detection of large size bacterial aerosols. Low magnitude of the limit of detection looks very promising for sensitive detection of highly pathogenic airborne bacteria in the ambient air. Significance and Impact of the Study: The suggested technology based on a simple model organism is one of the first attempts to develop a real-time monitor for reliable detection of airborne bacteria. The outcomes would be of strong interest of professionals involved in monitoring and/or control of pathogenic airborne bacteria, including Legionella, Mycobacterium tuberculosis and Bacillus anthracis

Surface plasmon resonance-based real-time bioaerosol detection

Aims: Rapid and precise bioaerosol detection in different environments has become an important research and technological issue over last decades. Previously, we employed a real-time PCR protocol in conjunction with personal bioaerosol sampler for rapid detection of airborne viruses. The approach has been proved to be specific and sensitive. However, a period of time required for entire procedure was in manner of hours. Some new developments are required to decrease the detection time down to real-time protocols. Methods and Results: Presently, a surface plasmon resonance (SPR)-based immunosensor that coupled with a specific antigen-antibody reaction could offer sensitive, specific, rapid and label-free detection. This study describes the possibility of combining the personal sampler with SPR technology for qualitative and extremely rapid detection of airborne micro-organisms. Common viral surrogate MS2 bacteriophage, frequently used in bioaerosol studies, was employed as a model organism. The results of the sensor functionalizing procedure with monoclonal anti-MS2 antibody and optimization of the chip performance are presented. The SPR-based detection of the airborne virus was found to be very fast; the viral presence was detected in less than 2 min, and the entire procedure (sampling and analysis) was undertaken in 6 min, which could be considered as real-time detection for this type of measurements. Conclusions: The combination of SPR with the personal sampler targeted towards bioaerosol detection was proven to be feasible. The SPR sensor was found to be highly stable and suitable for multiple utilizations without significant decrease in response. The suggested approach opens new possibilities for the development of portable and rapid (almost real time) bioaerosol monitors. Significance and Impact of the Study: This technology is the first in the world real-time bioaerosol monitor. This outcome would be of strong interest to individuals representing public health, biosecurity, defence forces, environmental sciences and many others

Photon-photon interaction under light localization in a system of conducting nanoparticles

It is shown that, under conditions of light localization in a system of scatterers, effective photon-photon interaction appears. This interaction is related to neither nonlinearity of medium nor nonlocal interaction of polarization-entangled photon pairs. It is related to the complex topology of photon trajectories. Taking into account this interaction, the scattering cross section of photon pairs is calculated. It is shown that this cross section contains only an extra degree of the small Rayleigh factor in comparison with the classic Rayleigh cross section. The proposed approach could potentially open a gate for controlling light by alternative light fluxes, eliminating the need for slow optoelectronic converters

Portable automatic bioaerosol sampling system for rapid on-site detection of targeted airborne microorganisms

Bioaerosols could cause various severe human and animal diseases and their opportune and qualitative precise detection and control is becoming a significant scientific and technological topic for consideration. Over the last few decades bioaerosol detection has become an important bio-defense related issue. Many types of portable and stationary bioaerosol samplers have been developed and, in some cases, integrated into automated detection systems utilizing various microbiological techniques for analysis of collected microbes. This paper describes a personal sampler used in conjunction with a portable real-time PCR technique. It was found that a single fluorescent dye could be successfully used in multiplex format for qualitative detection of numerous targeted bioaerosols in one PCR tube making the suggested technology a reliable "first alert" device. This approach has been specifically developed and successfully verified for rapid detection of targeted microorganisms by portable PCR devices, which is especially important under field conditions, where the number of microorganisms of interest usually exceeds the number of available PCR reaction tubes. The approach allows detecting targeted microorganisms and triggering some corresponding sanitary and quarantine procedures to localize possible spread of dangerous infections. Following detailed analysis of the sample under controlled laboratory conditions could be used to exactly identify which particular microorganism out of a targeted group has been rapidly detected in the field. It was also found that the personal sampler has a collection efficiency higher than 90% even for small-sized viruses (>20 nm) and stable performance over extended operating periods. In addition, it was found that for microorganisms used in this project (bacteriophages MS2 and T4) elimination of nucleic acids isolation and purification steps during sample preparation does not lead to the system sensitivity reduction, which is extremely important for development of miniature bioaerosol monitoring instrumentation in the future. © 2012 The Royal Society of Chemistry

Portable automatic bioaerosol sampling system for rapid on-site detection of targeted airborne microorganisms

Bioaerosols could cause various severe human and animal diseases and their opportune and qualitative precise detection and control is becoming a significant scientific and technological topic for consideration. Over the last few decades bioaerosol detection has become an important bio-defense related issue. Many types of portable and stationary bioaerosol samplers have been developed and, in some cases, integrated into automated detection systems utilizing various microbiological techniques for analysis of collected microbes. This paper describes a personal sampler used in conjunction with a portable real-time PCR technique. It was found that a single fluorescent dye could be successfully used in multiplex format for qualitative detection of numerous targeted bioaerosols in one PCR tube making the suggested technology a reliable "first alert" device. This approach has been specifically developed and successfully verified for rapid detection of targeted microorganisms by portable PCR devices, which is especially important under field conditions, where the number of microorganisms of interest usually exceeds the number of available PCR reaction tubes. The approach allows detecting targeted microorganisms and triggering some corresponding sanitary and quarantine procedures to localize possible spread of dangerous infections. Following detailed analysis of the sample under controlled laboratory conditions could be used to exactly identify which particular microorganism out of a targeted group has been rapidly detected in the field. It was also found that the personal sampler has a collection efficiency higher than 90% even for small-sized viruses (>20 nm) and stable performance over extended operating periods. In addition, it was found that for microorganisms used in this project (bacteriophages MS2 and T4) elimination of nucleic acids isolation and purification steps during sample preparation does not lead to the system sensitivity reduction, which is extremely important for development of miniature bioaerosol monitoring instrumentation in the future. © 2012 The Royal Society of Chemistry

Localization and Poincaré catastrophe in the problem of a photon scattering on a pair of Rayleigh particles

It is shown that complexities in a problem of elastic scattering of a photon on a pair of Rayleigh particles (two small metallic spheres) are similar to the complexities of the classic problem of three bodies in celestial mechanics. In the latter problem, as is well known, the phase trajectory of a system becomes a nonanalytical function of its variables. In our problem, the trajectory of a virtual photon at some frequency could be considered such as the well-known Antoine set (Antoine's necklace) or a chain with interlaced sections having zero topological dimension and fractal structure. Such a virtual "zero-dimensional" photon could be localized between the particles of the pair. The topology suppresses the photon's exit to the real world with dimensional equal-to-or-greater-than units. The physical reason for this type of photon localization is related to the "mechanical rigidity" of interlaced sections of the photon trajectory due to a singularity of energy density along these sections. Within the approximations used in this paper, the effect is possible if the frequency of the incident radiation is equal to double the frequency of the dipole surface plasmon in an isolated particle, which is the only character frequency in the problem. This condition and transformation of the photon trajectory to the zero-dimensional Antoine set reminds of some of the simplest variants of Poincaré's catastrophe in the dynamics of some nonintegrable systems. The influence of the localization on elastic light scattering by the pair is investigated

Localization of electromagnetic field on the "Brouwer-island" and liquid metal embrittlement

Liquid metal embrittlement (LME) manifests itself as a sudden destruction of a metal sample if it is covered by a thin liquid film of eutectic mixture of specially selected metals. The proposed theoretical model of this phenomenon is based on an assumption related to the possibility of electromagnetic field localization in folds of interface between the phases or components of eutectic mixture filling cracks in solid metal surface (the typical example is In-Ga eutectic on Al-surface). Based on simultaneous presence of three different components in each space point of eutectic mixture (homogeneous In + Ga melt, solid In, and solid Ga), the system of interface folds could be simulated by the Brouwer surface - well known in topology. This surface separates three different components presented at each of its point. Such fractal surfaces posses by a finite volume. The volume occupied by the surface is defined as a difference between the eutectic mixture volume and the sum of volumes of its components. We investigate localization of external electromagnetic radiation in this system of folds. Due to very large magnitude of effective dielectric permeability of the considered system, at relative small volume change and fractal dimension of interface close to the value 3, the wave length of incident radiation inside the system is considerably decreased and multiscale folds are filled with localized photons. A probability of this process and the life time of the localized photons are calculated. The localized photons play crucial role in destruction of primary cracks in the metal surface. They are capable "to switch of" the Coulomb attraction of charge fluctuations on opposite "banks" of the crack filled with the eutectic. As a result, the crack could break down

Interference corrections to light scattering and absorption by metal nanoparticles

An irreducible four-point vertex composed of the most-crossed diagrams involved in Bethe-Salpeter equation for an averaged two-photon propagator in a system of metal nanoparticles was calculated directly in coordinate representation without the traditional introduction of an EM-energy diffusion coefficient. These diagrams describe the interference of amplitudes corresponding to two possible ways for a photon to pass the closed loop on its trajectory. Localization is interpreted as a bound state generation of two virtual photons passing the loop clockwise and counterclockwise. This bound state is described by a pole of the irreducible vertex. The influence of this interference correction on light scattering and effective absorption by a random system of particles is investigated