The Effects of Pulsed UV Light Implementation on the Preservation Duration of Şavak Cheese Made from Raw Milk

This study aimed to investigate the effect of pulsed UV light on the the preservation of the Şavak cheese. In this study, the samples of Savak cheese (average 2 cm) that were produced from raw milk were exposed to two-sided pulsed UV light. The microbial analysis (enterobacteria, psychrophilic aerob, lactic acid, sulphate reducing bacteria, S.aureus and yeast-fungus) and chemical analysis (acidity, pH and the number of thiobarbituric acid) of şavak cheese were performed during storage time (25 days) at 4°C. According to the results, spoilage was observed in the control group after ten days, Group 1 was the best in terms of microbiological quality. When experimental samples were compared to the control group, no statistically differences were observed in terms of TBA, acidity, and pH value.

N,N′-bis(3-methylphenyl)-N,N′-dyphenylbenzidine Based Distributed Feedback Lasers with Holographically Fabricated Polymeric Resonators

The molecule N,N′-bis(3-methylphenyl)-N,N′-dyphenylbenzidine (TPD) has been widely used in optoelectronic applications, mainly for its hole-transporting properties, but also for its capability to emit blue light and amplified spontaneous emission, which is important for the development of organic lasers. Here, we report deep-blue-emitting distributed feedback (DFB) lasers based on TPD dispersed in polystyrene (PS), as active media, and dichromated gelatin layers with holographically engraved relief gratings, as laser resonators. The effect of the device architecture (with the resonator located below or on top of the active layer) is investigated with a dye (TPD) that can be doped into PS at higher rates (up to 60 wt%), than with previously used dyes (<5 wt%). This has enabled changing the index contrast between film and resonator, which has an important effect on the laser performance. With regards to thresholds, both architectures behave similarly for TPD concentrations above 20 wt%, while for lower concentrations, top-layer resonator devices show lower values (around half). Remarkably, the operational durability of top-layer resonator devices is larger (in a factor of around 2), independently of the TPD concentration. This is a consequence of the protection offered by the resonator against dye photo-oxidation when the device is illuminated with pulsed UV light.

Preharvest Management and Postharvest Intervention Strategies to Reduce Escherichia coli Contamination in Goat Meat: A Review

Goat meat is the main source of animal protein in developing countries, particularly in Asia and Africa. Goat meat consumption has also increased in the US in the recent years due to the growing ethnic population. The digestive tract of goat is a natural habitat for Escherichia coli organisms. While researchers have long focused on postharvest intervention strategies to control E. coli outbreaks, recent works have also included preharvest methodologies. In goats, these include minimizing animal stress, manipulating diet a few weeks prior to processing, feeding diets high in tannins, controlling feed deprivation times while preparing for processing, and spray washing goats prior to slaughter. Postharvest intervention methods studied in small ruminant meats have included spray washing using water, organic acids, ozonated water, and electrolyzed water, and the use of ultraviolet (UV) light, pulsed UV-light, sonication, low-voltage electricity, organic oils, and hurdle technologies. These intervention methods show a strong antimicrobial activity and are considered environmentally friendly. However, cost-effectiveness, ease of application, and possible negative effects on meat quality characteristics must be carefully considered before adopting any intervention strategy for a given meat processing operation. As discussed in this review paper, novel pre- and post-harvest intervention methods show significant potential for future applications in goat farms and processing plants.

A novel streak velocimetry technique based on 2D fits of decaying phosphor particle images

A new 2D velocimetry technique based on streaks formed by individual phosphor particles, which are moving during their luminescence decay following pulsed excitation is proposed in this study. Tin-doped phosphor particles (Sr,Mg)3(PO4)2:Sn2+ are dispersed into flows and excited by a pulsed UV light sheet. During the phosphor decay time (~27 µs), the emission streaks due to particle motion are recorded. A 2D fitting is then applied on each particle streak against the analytical expression of intensity distribution, to obtain the velocity information for each particle. Unlike Particle Tracking Velocimetry (PTV) this technique does not rely on any particle image searching procedure.

Apple Juice Preservation Using Combined Nonthermal Processing and Antimicrobial Packaging

This study investigated the effectiveness of pulsed electric fields (PEF) treatment (19, 23, 30 kV/cm), pulsed UV light (PL) treatment (5 to 50 s; 1.04 J/cm 2 /s), and antimicrobial packaging (AP) treatment, either individually or combined, in inactivating bacteria and in maintaining the quality of fruit juices. Apple juice samples, inoculated with Escherichia coli K12 or native mold and yeast (M&Y), were treated by a bench scale PEF and/or PL processing systems and stored in glass jars with antimicrobial caps containing 10 µl of carvacrol (AP). The reduction in microbial populations and the physicochemical properties of juice samples were determined after treatments and during storage at 10°C. The treatments included PL (5 to 50 s; 1.04 J/cm 2 /s ), PEF (19, 23, 30 kV/cm), PEF followed by PL (PEF+PL), PL followed by PEF (PL+PEF), and PEF+PL+AP. PEF treatments from 19 to 30 kV/cm (PEF19, PEF23, PEF30) achieved E. coli reduction by 2.0, 2.6 and 4.0 log CFU/ml, respectively; PL treatments for 10 to 50 seconds (PL10, PL20, PL30, PL40, PL50) achieved E. coli reduction by 0.45, 0.67, 0.76, 2.3, and 4.0 log CFU/ml, respectively. There were no significant (p&gt;0.05) differences between the combined PL20+PEF19 and PEF19+PL20 treatments; both treatments reduced E. coli K12 populations to non-detectable levels (&gt; 5 log reduction) after 7 days. Both PEF+PL and PEF+PL+AP treatments achieved over 5 log reduction of M&Y; however, juice samples subject to PEF+PL+AP treatment had lower M&Y counts (2.9 log) than samples subject to PEF+PL treatment (3.9 log) after 7 days. There were no significant (p &gt; 0.05) differences in pH, acidity, total soluble solid contents among all samples after treatments. Increased PL treatment times reduced color a*, b* values, total phenolics and carotenoid contents. This study provides valuable information to juice processors for consideration and design of nonthermal pasteurization of juice products.

Pulsed Broad-Spectrum UV Light Effectively Inactivates SARS-CoV-2 on Multiple Surfaces and N95 Material

The ongoing SARS-CoV-2 pandemic has resulted in an increased need for technologies capable of efficiently disinfecting public spaces as well as personal protective equipment. UV light disinfection is a well-established method for inactivating respiratory viruses. Here, we have determined that broad-spectrum, pulsed UV light is effective at inactivating SARS-CoV-2 on multiple surfaces in vitro. For hard, non-porous surfaces, we observed that SARS-CoV-2 was inactivated to undetectable levels on plastic and glass with a UV dose of 34.9 mJ/cm2 and stainless steel with a dose of 52.5 mJ/cm2. We also observed that broad-spectrum, pulsed UV light is effective at reducing SARS-CoV-2 on N95 respirator material to undetectable levels with a dose of 103 mJ/cm2. We included UV dosimeter cards that provide a colorimetric readout of UV dose and demonstrated their utility as a means to confirm desired levels of exposure were reached. Together, the results presented here demonstrate that broad-spectrum, pulsed UV light is an effective technology for the in vitro inactivation of SARS-CoV-2 on multiple surfaces.

Pulsed broad-spectrum UV light effectively inactivates SARS-CoV-2 on multiple surfaces

The ongoing SARS-CoV-2 pandemic has resulted in an increased need for technologies capable of efficiently disinfecting public spaces as well as personal protective equipment. UV light disinfection is a well-established method for inactivating respiratory viruses. Here, we have determined that broad-spectrum, pulsed UV light is effective at inactivating SARS-CoV-2 on multiple surfaces. For hard, non-porous surfaces we observed that SARS-CoV-2 was inactivated to undetectable levels on plastic and glass with a UV dose of 34.9 mJ/cm2 and stainless steel with a dose of 52.5 mJ/cm2. We also observed that broad-spectrum, pulsed UV light is effective at reducing SARS-CoV-2 on N95 respirator material to undetectable levels with a dose of 103 mJ/cm2. We included UV dosimeter cards that provide a colorimetric readout of UV dose and demonstrated their utility as a means to confirm desired levels of exposure were reached. Together, the results present here demonstrate that broad-spectrum, pulsed UV light is an effective technology for the inactivation of SARS-CoV-2 on multiple surfaces.