Microbicidal Effects

PureBright antimicrobial mechanisms are based on the sensitivity of microorganisms to UV wavelengths that are readily absorbed by microbial nucleic acids and proteins, and the very high power and intensity of the flash.

The antimicrobial effects of one to several flashes are dramatic. PureBright treatment at 1.5 J/cm2 kills 7 logs of Staphylococcus aureus ATCC 27661 suspended in 25-mL droplets dried on the surface of microbiological media.

Figure 2 shows the pulsed light kill kinetics obtained using the microdrop assay for a number of different bacteria and spores. The results show 7 to 9 logs/cm2 reduction using a few flashes.

PureBright kill dynamics are superior to conventional ultraviolet light from a high-intensity mercury vapor lamp. Using relatively UV-resistant Aspergillus niger spores inoculated and dried on a packaging surface, conventional continuous wave UV kills 3.5 to 4.5 logs in 6 to 10 s with no appreciable increase in kill with additional treatment time. By comparison, PureBright kills more than 7 logs of A. niger spores with a few flashes applied in a fraction of

AC Power

AC Power

Low power source

Power conditioning system

High-energy pulsed dischage

Low power source

Power conditioning system

Charging

Pulse compression

Figure 1. Pulsed energy processing.

---B. pumilus spores

-----Listeria monocytogenes

---B. pumilus spores

-----Listeria monocytogenes

No survivors

Treatment fluence (J/cm2) Figure 2. Pulsed light kill kinetics.

lutions. In general, colors will inhibit the UV transmission and microbial kill.

The olefins (polyethylene, polypropylene), acrylics, many polyamides and nylons, ethylene acrylic acid, EVA, EVOH, and similar plastics that transmit in the ultraviolet are good candidates for PureBright treatment through the package. Plastics with aromatic hydrocarbon backbones, side groups, or additives generally absorb UV too strongly to permit treatment through the package.

No adverse chemical or functionality effects on plastic packaging materials have been found using a variety of plastics treated with PureBright at levels in excess of those needed to provide appropriate microbial kill.

PureBright is also effective for treating metal or plastic bottle caps. Tests using four different types and configurations of caps have shown total kill of 4 to 5 logs of inoculated A. niger conidiospores using 2 to 6 flashes.

a second. This dynamic provides the effectiveness required for high sterility assurance (Fig. 3).

How To Reduce Acne Scarring

How To Reduce Acne Scarring

Acne is a name that is famous in its own right, but for all of the wrong reasons. Most teenagers know, and dread, the very word, as it so prevalently wrecks havoc on their faces throughout their adolescent years.

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