Methods of Introduction of MgO Nanoparticles Into Bi-2212/Ag Tapes

The effect of addition of ultra-fine MgO particles, obtained by Mg combustion, in Bi-2212/Ag tapes was investigated. Bi-2212/Ag tapes were prepared by coating and partial melt processing. Four different methods of MgO particles embedment were applied in green tape preparation; settlement of MgO in Bi-2212, pre-mixing of MgO in the solvent, deposition of the MgO into the solvent, and deposition of MgO onto the surface of Bi-2212. Microstructural studies of processed tapes show that uniformity of MgO particles distribution in Bi-2212 matrix depends on the methods of tape preparation. MgO particles, introduced in Bi-2212 matrix by all applied methods, significantly enhanced transport properties of the tapes. The Jc degradation with the increase of magnetic field and/or temperature in all doped samples was significantly lower compared to un-doped Bi-2212 samples. The best improvement was achieved when MgO particles were introduced into Bi-2212 matrix by settlement method of the tape coating. The improvement also depends on a magnitude of the magnetic field and operating temperatures

In-situ rapid bioaerosol detection in the ambient air by miniature multiplex PCR utilizing technique

Given the current problems associated with the COVID-19 pandemic, research in the field of rapid and reliable detection and characterization of airborne pathogenic microorganisms is becoming of exceptional urgency. This project is focused on development of portable first alert bioaerosol monitoring technique utilizing personal bioaerosol sampler capable of high efficient trapping of airborne microorganisms into collecting liquid along with a laser based mini Polymerase Chain Reaction (PCR) machine in a multiplex format (multi-target simultaneous detection) with following identification of minimal time period required for detection of any airborne microbial targets in the ambient air. The experimental program was undertaken under controlled laboratory conditions utilizing of up to 7 plex PCR format for detection of airborne microbial targets in the dynamic aerosol chamber. The technology demonstrated efficient operation and was capable of detecting airborne microbial targets during even shortest experimental sampling periods of 10 s. The total time of detection/analysis was less than 40 min. The proposed sampling timeframe represents realistic scenario of bioaerosol exposure of humans’ moving through areas potentially contaminated by bioaerosol originated from natural or anthropogenic sources. The research outcomes look very promising enabling development of new generation of portable, reliable and fast bioaerosol monitors, which are unique and highly demanded in the areas of defence, public health and others

New personal sampler for viable airborne viruses: feasibility study

While various sampling methods exist for collecting and enumerating airborne bacteria and fungi, no credible methodology has yet been developed for airborne viruses. A new sampling method for monitoring the personal exposure to bioaerosol particles has recently been developed and evaluated with bacteria and fungi. In this method, bacterial/fungal aerosol is aspirated and transported through a porous medium, which is submerged into a liquid layer. As the air is split into numerous bubbles, the particles are scavenged by these bubbles and effectively removed. The current feasibility study was initiated to evaluate the efficiency of the new personal sampler prototype ("bubbler") with airborne viable viruses. Two common viral strains, Influenza (stress-sensitive) and Vaccinia (robust), were aerosolized in the test chamber and collected by two identical "bubblers" that operated simultaneously for a duration of upto 5 min. A virus maintenance liquid, proven to be the optimum collecting environment for the test organisms, was used as a collection fluid. After sampling, the collecting fluid was analyzed and the viral recovery rate was determined. The overall recovery (affected not only by the sampling but also by the aerosolization and the aerosol transport) was 20% for Influenza virus and 89% for Vaccinia virus. The new sampling method was found feasible for the collection and enumeration of robust airborne viruses

Personal sampler for viable airborne microorganisms: Main development stages

A new personal bioaerosol sampler has been developed and verified as an efficient tool for monitoring of viable/non-viable airborne microorganisms, including bacteria, fungi, and viruses. The operational principle of the device is based on continuous passage of an air sample through porous media submerged into a liquid layer. During motion along narrow and tortuous ways inside the porous media, the air stream is split into a large number of ultra small bubbles with the particulates are being scavenged by these bubbles and, thus, effectively trapped. The device was initially verified for monitoring of viable airborne bacteria and fungi, firstly, under controlled laboratory conditions and later in a field. It was demonstrated that bacterial recovery rates for these two groups of microorganisms were very high and the device was found to be fully feasible for such monitoring. The next step of the device investigation was performed in the laboratory on monitoring viable airborne viruses with a range of sensitivities to physical and biological stresses. As the result, the new personal sampler demonstrated a very high recovery rate even for viruses which are rather sensitive to environmental stress (Avian Influenza, SARS, Mumps, etc.). Some following field studies, undertook in a hospital and animal houses, also demonstrated an excellent performance of the new device for selective and reliable monitoring of viable airborne viruses even in environments highly contaminated by other microorganisms. This paper reviews the main development staged of the new personal bioaerosol sampler

Development and evaluation of a new personal sampler for culturable airborne microorganisms

The objective of this study was to develop a new personal sampler for viable airborne microorganisms and to evaluate its performance under controlled laboratory conditions and in a field. In the sampler, air is bubbled through a porous medium submerged in a liquid layer, as has earlier been demonstrated to be highly efficient for air purification. The prototype had the physical collection efficiency >95% for particles >0.32 μm in aerodynamic diameter during 8 h of continuous operation. The pressure drop across the sampler was below 1700 Pa, much lower than that of most conventional bioaerosol samplers. The collection liquid losses due to evaporation and aerosolization did not exceed 18% in 8 h and the culturability of sampled microorganisms remained high: the recovery rate of stress-sensitive gram-negative P. fluorescens bacteria was 61±20%; for stress-resistant B. subtilis bacteria and A. versicolor fungal spores it was 95±9% and 97±6%, respectively. Six identical personal samplers were tested simultaneously on a simplified human manikin in an office environment. The culturable microbial concentration data obtained during 2, 4 and 8-h sampling were not affected by the sampling time. Inter-sample variation did not exceed 30%. The laboratory and field evaluations have demonstrated that the new sampler is capable of long-term personal sampling of airborne culturable microorganisms. The estimation of the detection limits has indicated that the sampler is capable of monitoring microbial exposure in the environments with the bacterial concentrations above 15 CFU/m3 and fungal concentrations above 5 CFU/m3 when using a sampling time of 8 h

A new thermophoretic precipitator for off-line particle analysis

A new thermophoretic particle precipitator has been developed for representative and efficient collection of aerosol particles from the ambient air and technological pipelines. The device consists of hot and cold plates (5×5cm) capable of operation at temperature gradients ranging from 20000 to 100000K/m. A gas sample is made to pass through a 1-mm slot between the plates at a flow rate of up to 1.5L/min, which makes the device suitable for operation in conjunction with common aerosol instruments including DMA and diffusion batteries with similar operational flow rates. It was shown that the efficiency of the device was highest for the lowest gas flow rate used (0.3L/min) reaching a level of above 99%. The efficiency was decreased reaching its minimal values at the highest flow rate investigated (1.5L/min). However, even for highest flow rate, the average efficiency for removal of particle smaller than 60nm was around 50%

Collection of airborne microorganisms into liquid by bubbling through porous medium

A new method for the removal of airborne particles by air bubbling through fibrous filters immersed into a liquid has recently been developed (Agranovski et al. 1999) and shown to be very efficient for cleaning air environments with ultra-fine aerosol particles. The principal objective of the present study was to evaluate the new bubbling technique for the collection of airborne bacteria into a liquid for subsequent physical and microbiological analysis. It was found that the technique is capable of achieving a physical collection efficiency of 98.5% or higher for particles larger than 0.3 wm in aerodynamic diameter. The physical collection efficiency of the prototype bubbler remained at that high level for 8 h of continuous operation with negligible variation of the pressure drop across the device. Evaporation of the collection fluid did not exceed 20% during 8 h, and the reaerosolization effect on the physical collection efficiency of the bubbler prototype was <8%. The recovery rate of gram-negative Pseudomonas fluorescens bacteria collected for 20 min was shown to be as high as 74% - 10%. Its decrease with time was not statistically significant: the recovery rate reached 63% - 15% and 58% - 16% after 4 and 8 h of continuous operation, respectively. Thus the bubbling technique was demonstrated to be suitable for collecting viable airborne bacteria even if they are sensitive to the stress