Survival of Listeria Strains and Shelf Life Determination of Fresh Blueberries (Vaccinium corymbosum) Treated with Cold Atmospheric Plasma.

Fresh blueberries are delicate, hand-picked, packaged, and refrigerated fruits vulnerable to spoilage and contamination. Cold atmospheric plasma (CAP) is a promising antimicrobial technology; therefore, this study evaluated the CAP treatment effect on acid-tolerant Listeria innocua and Listeria monocytogenes and evaluated changes in the quality of the treated fruit. Samples were spot-inoculated with pH 5.5 and 6.0 acid-adapted Listeria species. Samples were treated with gliding arc CAP for 15, 30, 45, and 60 s and evaluated after 0, 1, 4, 7, and 11 days of storage at 4 °C and 90% humidity for the following quality parameters: total aerobic counts, yeast and molds, texture, color, soluble solids, pH, and titratable acidity. CAP treatments of 30 s and over demonstrated significant reductions in pathogens under both the resistant strain and pH conditions. Sixty-second CAP achieved a 0.54 Log CFU g-1 reduction in L. monocytogenes (pH 5.5) and 0.28 Log CFU g-1 for L. monocytogenes (pH 6.0). Yeast and mold counts on day 0 showed statistically significant reductions after 30, 45, and 60 s CAP with an average 2.34 Log CFU g-1 reduction when compared to non-CAP treated samples. Quality parameters did not show major significant differences among CAP treatments during shelf life. CAP is an effective antimicrobial treatment that does not significantly affect fruit quality.

Functionalization of stable fluorescent nanodiamonds towards reliable detection of biomarkers for Alzheimer's disease.

BACKGROUND: Stable and non-toxic fluorescent markers are gaining attention in molecular diagnostics as powerful tools for enabling long and reliable biological studies. Such markers should not only have a long half-life under several assay conditions showing no photo bleaching or blinking but also, they must allow for their conjugation or functionalization as a crucial step for numerous applications such as cellular tracking, biomarker detection and drug delivery. RESULTS: We report the functionalization of stable fluorescent markers based on nanodiamonds (NDs) with a bifunctional peptide. This peptide is made of a cell penetrating peptide and a six amino acids long ß-sheet breaker peptide that is able to recognize amyloid ß (Aß) aggregates, a biomarker for the Alzheimer disease. Our results indicate that functionalized NDs (fNDs) are not cytotoxic and can be internalized by the cells. The fNDs allow ultrasensitive detection (at picomolar concentrations of NDs) of in vitro amyloid fibrils and amyloid aggregates in AD mice brains. CONCLUSIONS: The fluorescence of functionalized NDs is more stable than that of fluorescent markers commonly used to stain Aß aggregates such as Thioflavin T. These results pave the way for performing ultrasensitive and reliable detection of Aß aggregates involved in the pathogenesis of the Alzheimer disease.

Current measurement by Faraday effect on GEPOPU.

The design of an optical current sensor to be used in a pulsed power generator is presented. The current sensor is based on the polarization rotation by the Faraday effect. GEPOPU is a pulsed power generator, 110 kA, 120 ns double transit time, 1.5 Ω coaxial geometry, and current rise time of 50 ns. Two different optical geometries surrounding the conductor were tried, using Amici roof prism and pentaprism to go around the current once, as a way to preserve the state of polarization along the optical path by means of complementary reflections within the sensing element. We believe this to be the first time that such large and rapidly varying currents have been measured with this configuration. The values obtained for both geometries agree with the values obtained with a Rogowski coil. The traces obtained are completely noise-free and no significant time lag has been observed between the current determined from the Faraday rotation and the current measured using a Rogowski coil.

Simple holographic polarogram.

A new technique capable of obtaining quantitative values of the rotation angle of the polarization vector by using holography is presented. This is a two-stage holographic process; during the recording stage a hologram of the object of interest is obtained. The reference beam is composed of two beams that form a small angle between them and keep their polarization states at right angles to each other. In the reconstruction stage of the hologram, two images from the hologram are obtained along two different angles. As a result of the interference between these two images, a set of parallel fringes is formed at the image plane. The fringe contrast on the reconstruction is related to the angle of the polarization vector of the light at each position on the image plane. Measurements of the rotation of the polarization angle of a fraction of a degree were obtained. The main application of this technique is in the study of transient phenomena, where single-shot measurements are the only means of obtaining reliable data.