Real-time detection of an airborne microorganism using inertial impaction and mini-fluorescent microscopy

To achieve successful real-time detection of airborne pathogenic microorganisms, the problem must be considered in terms of their physical size and biological characteristics. We developed an airborne microorganism detection chip to realize the detection of microorganisms, ensuring compactness, sensitivity, cost-efficiency, and portability, using three key components: an inertial impaction system, a cartridge-type impaction plate, and a mini-fluorescent microscope. The inertial impaction system was used to separate microorganisms in terms of their aerodynamic particle size, and was fabricated with three impaction stages. Numerical analysis was performed to design the system; the calculated cutoff diameter at each impaction stage was 2.02 (first stage), 0.88 (second stage), and 0.54 μm (third stage). The measured cutoff diameters were 2.24, 0.91, and 0.49 μm, respectively. A cartridge-type impaction plate was used, composed of molded polydimethylsiloxane (PDMS) and an actual impaction region made of a SYBR green I dye-stained agar plate. A mini-fluorescent microscope was used to distinguish microbes from non-biological particles. Images of the microorganisms deposited at the impaction zone were obtained via mini-fluorescent microscopy, and fluorescent intensities of the images were calculated using in-house image-processing software. The results showed that the developed system successfully identified aerosolized biological particles from non-biological particles in real time

Pattern of Failure in Bladder Cancer Patients Treated with Radical Cystectomy: Rationale for Adjuvant Radiotherapy

Thus far, the role of adjuvant radiotherapy (RT) after radical cystectomy (RC) in urinary bladder cancer patients has yet to be defined. The purpose of this study is to analyze patterns of failure, and suggest the rationale for RT. Between 1986 and 2005, a total of 259 patients treated with RC and pelvic lymph node dissection was enrolled. The age range was 27-82 yr (median, 62 yr). Node positivity increased according to tumor staging. Patients were divided into the following two groups based on pathologic analysis: organ-confined disease group (n=135) and extravesical/lymph node-positive disease group (n=80). Pelvic failures (PF) were observed in 8 (4.9%) in organ-confined disease group, and 21 (21.7%) in extravesical/lymph node-positive disease group. Five-year PF-free survival rates were 91.2% in organ-confined disease group and 68.0% in extravesical/lymph node-positive disease group. Five-year cancer-specific survival rates were 86.2% in organ-confined disease group and 53.9% in extravesical/lymph node-positive disease group. In conclusion, a relatively high PF rate was observed in extravesical lymph node-negative and lymph node-positive disease patients in this study. Adjuvant pelvic RT may be considered to reduce pelvic failures in extravesical lymph node-positive bladder cancer. Future prospective trials are required to test the clinical benefit of adjuvant RT

On-Road Measurements of Ultrafine Particles and Associated Air Pollutants in a Densely Populated Area of Seoul, Korea

Spatial distributions of ultrafine particles (UFPs; 6 < Dp < 560 nm) and related gaseous and particulate pollutants were estimated from on-road measurements undertaken on busy roadways of Seoul, Korea, using a mobile laboratory (ML). The objectives of the study were to determine the spatial variations in UFP size distributions and concentrations of associated gaseous and particulate pollutants and to observe the relationships of UFP number concentrations with other pollutants on roadways in an urban area in Korea. The pollutants associated with diesel vehicles such as black carbon (BC) and particle-bound polycyclic aromatic hydrocarbons (PM-PAHs) exhibited a high determination coefficient (r2 = 0.65), indicating the influence of diesel vehicles on emissions in the study area. Further supporting evidence for the influence of diesel vehicles on emissions was given by the higher determination coefficients of PM-PAHs and BC concentrations with larger size-classified particles, ranging from 60 < Dp < 220 nm, than with total UFP number concentrations or smaller particles in the 6 < Dp < 60 nm size range. Peak concentrations of measured pollutants were observed mostly at intersections, reflecting the relationships of transient driving modes (i.e., deceleration and acceleration) with emissions of UFPs, associated pollutants, and concentrated traffic volumes at such locations

Effects of Electric Field Strength on an Antimicrobial Air Filter

We investigated the effects of a surrounding electric field (EF) on the performance of antimicrobial air filters coated with natural-product nanoparticles. The filtration efficiency of the control filter increased with increasing EF strength, whereas the filtration efficiency of the antimicrobial filter did not, probably because its original efficiency was already high (> 99%) and non- or relatively weakly charged bacterial aerosols were hardly affected by EF strength. The bacterial deposition profiles through the depth of the antimicrobial filters were evaluated. The bacterial concentration at depths of 0–68 µm was increased by about 30% at an EF of 7.7 kV/cm compared with the concentration at 0 kV/cm. Scanning electron microscopy revealed that at 7.7 kV/cm, but not at 0 kV/cm, the bacteria formed dendrites on the fibers of the filter, and the concentration of bacteria deposited on the fibers at 7.7 kV/cm was two to three times that at 0 kV/cm. In antimicrobial tests, the performance of the antimicrobial filters increased with increasing concentration of antimicrobial nanoparticles, but the effectiveness differed between 0 and 7.7 kV/cm. At an identical nanoparticle concentration, the inactivation efficiency of the antimicrobial filter at 7.7 kV/cm was at most 23% lower than that at 0 kV/cm, because the relative increase in bacterial concentration and dendrite formation in the first layer of the antimicrobial filter at 7.7 kV/cm reduced the surface contact area between the bacteria and the antimicrobial nanoparticles. This study provides valuable information for developing a hybrid air purification system that serves various functions and can be used in an indoor environment

Effects of Surrounding Temperature on Antimicrobial Air Filters Coated with Sophora flavescens Nanoparticles

Bioaerosols, such as bacterial and fungal cells and their spores, are components of indoor airborne particulate matter and have been associated with human health problems as well as various environmental issues. Natural antimicrobial products have been used in air filters for bioaerosol control. However, natural products may lose some function due to their sensitivity to environmental factors such as temperature and humidity. In this study, we investigated the effects of temperature on antimicrobial fiber filters coated with nanoparticles of a natural product, namely, Sophora flavescens extract. Inactivation efficiency decreased with increasing temperature and treatment time. A quantitative chemical analysis of the filters revealed that the quantities of antimicrobial compounds decreased noticeably, with a consequent decrease in antimicrobial activity. In addition, the S. flavescens nanoparticles on the filter fiber surface melted gradually as treatment time increased at temperatures >100°C. This change in nanoparticle morphology in turn affected the pressure and filtration efficiency of filters, both of which decreased with increasing temperature and treatment time. These results could provide a scientific basis for the improvement of indoor air-quality control using antimicrobial air filters coated with S. flavescens nanoparticles