Application Of UV-C Research Articles

Evaluation of Germicidal UV-C Light for Suppression of Grape Powdery Mildew and Botrytis Bunch Rot in Western Oregon.

Germicidal UV light (UV-C) has been shown to effectively suppress several plant pathogens as well as some arthropod pests. Recent reports describe the efficacy of nighttime applications of UV-C at doses from 100 to 200 J/m2 in vineyards to reduce grape powdery mildew (Erysiphe necator). Our in vitro studies confirmed the efficacy of UV-C to inhibit germination of E. necator and Botrytis cinerea conidia, demonstrated a range of tolerances to UV-C within a collection of E. necator isolates, and showed growth stage-specific effects of UV-C on B. cinerea. Nighttime use of UV-C was evaluated at 48 to 96 J/m2 in small plot trials (<1,000 vines) from 2020 to 2023. Once- or twice-weekly UV-C applications significantly reduced the incidence of foliar powdery mildew compared with non-UV-C-treated controls (P < 0.02). Suppression of powdery mildew on fruit was less consistent, where once or twice weekly UV-C exposure reduced powdery mildew disease severity in 2020 (P = 0.04), 2021 (P = 0.02), and 2023 (P = 0.003) but less so in 2022 (P = 0.07). Bunch rot severity was not significantly reduced with UV-C treatment in any year of the study. Application of UV-C until the onset of fruit color change (veraison) also had a minimal effect on the fruit-soluble solids, pH, anthocyanins, or phenolics in harvested fruit at any UV-C dose or frequency (P > 0.10). Suppression of powdery mildew by nighttime application of UV-C at lower doses in small plots suggests that such treatments merit further evaluation in larger-scale studies in Western Oregon.

An energy efficiency and cost analysis of utilizing high-intensity profile UVC systems on air handling unit under cool-humid climate

The feasibility of the ultraviolet germicidal irradiation (UVGI) application has been proven over the past few decades, especially in disinfection performances; however, a small number of studies were found that explored the energy efficiency improvement and cost savings of real buildings by implementing the UVC systems on cooling coils. The goal of this study is to verify the energy efficiency improvements and cost savings of AHU in a real building environment by removing biofilms on the cooling coil surfaces with the UVC irradiation techniques that can provide higher lamp output (300 μW/cm2) as well as higher intensity levels (1000–4000 μW/cm2) on the cooling coil surfaces. A series of experiments were conducted in an AHU in a medical center located in Michigan, US, to estimate energy efficiency improvement of cooling coils, chiller, and fan with UVC application. The results show that after 7 weeks of UVC operation increased coil overall enthalpy-based thermal conductance by 15.62 %, achieved chiller-side energy savings by up to 28.2 %, reduced pump energy by 32.1 %, and fan energy by 17.7 %. A return on investment (ROI) based only on energy savings is estimated to be 43 % and has a payback period of 2.32 years. When the labor, chemical, and water-saving costs for coil cleaning were included, the ROI was increased to 49 % and reduced the payback period to 2.04 years. When it comes to UVC's disinfection performances, six pathogens showed a more than 99 % removal rate while Klebsiella pneumoniae and Clostridium difficile showed a relatively lower 94 % removal rate.

Efficacy of gaseous ozone and UVC radiation against Candida auris biofilms on polystyrene surfaces

The growth and attachment of highly resistant biofilms on/to polymer-based surfaces, including reusable medical devices is a significant health concern in infection control. The increasing prevalence of the multidrug-resistant yeast, Candida auris, has recently garnered immense interest as a contributor to healthcare-associated infections. In this study, we investigate the potential of disinfection processes (ozone, UVC, and ozone + UVC) to inactivate C. auris biofilms (NCPF 8971), grown on polystyrene surfaces. A bespoke decontamination chamber is used to expose the substrate for 20–60 mins, corresponding to ozone doses between 1000 and 3000 ppm.min and UVC doses between 2864 and 11,592 mJ/cm2, respectively. The performance of these 3 treatment methods against the biofilms and vegetative/planktonic cells of the organism is comparatively evaluated. While complete inactivation (> 8 log10 reduction, CFU/mL) of the vegetative cells is observed within 40 mins by all methods, the biofilms proved considerably difficult to inactivate. Only 3.3 log10 reduction was achieved using ozone for 40 min, whereas 7.2 log10 reduction was obtained using UVC for 40 min. A hybrid application of ozone and UVC improved the decontamination efficacy compared to their independent applications (i.e., ozone only and UVC only). Scanning electron microscopy results yielded new insights into the inactivation mechanisms; thus providing the needed foundation for newer developments in oxidation-based processes for biofilm mitigation and control.

Efecto de la UV-C en la calidad postcosecha de cítricos de la región nororiente del Valle del Cauca, Colombia

Ultraviolet short wave (UV-C) irradiation is an emerging technology employed in postharvest fruits treatment. This method facilitates a reduction in microbial load, triggers an elicitor effect, and prolongs the shelf life of fruits. In this study, UV-C was applied to rangpur red lime, Tahitian lime, and sweet orange cv. 'Sweety,' which are the primary citrus varieties cultivated in the northeastern region of Valle del Cauca, Colombia. The citrus fruits were exposed to UV-C irradiation for 5 min using a lamp positioned 11 cm above the work area. Subsequently, the fruits were stored in plastic baskets for 21 days at 26 °C with a relative humidity of 70%. Positive and negative control treatments were also implemented. The positive treatment involved samples treated with a 150 mg/L sodium hypochlorite solution for 5 min, while the negative treatment comprised samples without any postharvest treatment. The results revealed that UV-C application effectively delayed maturation, prevented granulation, and maintained the physicochemical parameters, morphology, and surface color of citrus fruits. In conclusion, UV-C shows promise as a technology for treating citrus fruits during the postharvest stage, offering a means to mitigate losses, and assuring food availability.

The combined application of ultrasound and UVC have the potential to control mature Listeria monocytogenes and Bacillus subtilis biofilms

The present study aims to determine the bactericidal and disintegrating effect of ultraviolet type C treatments combined with ultrasound against biofilms of Listeria monocytogenes and Bacillus subtilis formed at different incubation periods (i.e. 24, 48, and 72 h). Treatments applied are UVC doses ranging from 60 to 360 mJ/cm2 (5–30 s) and US doses of 5–15 min, depending on the maturity of biofilms and the microorganism. Initially, we investigated the effects of UVC on planktonic cells, revealing a significantly higher lethality in L. monocytogenes compared to B. subtilis (P < 0.05). Moreover, B. subtilis demonstrated greater resistance in both its spore and vegetative forms (P < 0.05). The application of UVC on biofilms demonstrates that, as the more structured and robust the biofilm is, the more difficult it is for UVC to penetrate the biofilm structure and reach the cells that conform them, which is why higher lethality is observed in the shortest formation period (i.e. 24 h). In addition, as the UVC dose increases, microorganisms show a higher resistance to the treatment, thus showing a greater reduction in the microbial population at lower doses. The single application of ultrasound (US) manages to reduce the cell load between 1 and 4 log CFU/cm2, depending on the microorganism and exposure time. The results obtained after the combination of both technologies achieve higher lethality, 5.2 log reductions at the lowest doses (i.e. applying 5 min of US and 5 s of UVC). Furthermore, the maximum reduction possible for these experiments (≥5.6 log) is achieved in any treatment applying a 15-s UVC exposure time. Significant differences are observed (P < 0.05) as the maturity stage increases ([+Let] 24a > 48b > 72c hours). The combination of these two technologies demonstrates highly promising outcomes across all examined bacterial structures, including spores and vegetative biofilms.

Grape Berry Morphology in Semi-Arid Climate of Tekirdağ: Evaluating the Effects of Environmental Factors and Stress Applications

The growth and development of grapes are influenced by various biotic and abiotic stresses. The presence of Vitis vinifera L. on Earth is threatened by the increase in abiotic stresses and biotic stresses due to global warming. On the other hand, grape quality and, consequently, berry characteristics can also be negatively affected by these stress factors. The hypothesis of this experiment is to determine the effects of biotic and abiotic stresses applied five days before harvest on the berries of live grapevines under field conditions. For this purpose, for two years (2016 and 2017), Cabernet-Sauvignon and Merlot grape varieties grafted onto the SO4 rootstock at Te-Ha Corp. vineyard were used. In the late pre-harvest period (five days before harvest), seven stress applications, including control, were implemented. The stress application methods included control, impact (1 minute with a plastic hammer at 08:00 and 19:00), leaf removal (removing all leaves), leaf injury (injuring all leaves by hitting with a stick), UV-C (1 minute at 08:00 and 19:00), vibration (1 minute of vibration at 08:00 and 19:00), and Botrytis cinerea Pers ex. Fr (once). The measurements of the features performed are as follows, in order: berry width-length (mm), bery volume (cm3), berry skin area (cm2/grain), berry skin area/berry flesh volume ratio (cm2/cm3), berry fresh-dry weight (g), 100 berry fresh weight (g), berry density (g/cm3), and % dry weight. As a result, it was observed that the applied abiotic and biotic stress treatments did not negatively affect berry characteristics in two years, especially in the second year. Therefore, the application of Shock action, UV-C, Vibration, Leaf injury, Leaf removal, and Botrytis cinerea for improving grape quality was found not to be objectionable.

Investigation of antimicrobial and anticancer activity of extracts obtained following UV application to Althaea officinalis L. callus cultures

Althaea officinalis L., a plant of the Malvaceae family, is widely used in alternative medicine. The aim of this study is to cultivate the Althaea officinalis plant under in vitro conditions to create an appropriate callus regeneration protocol and investigate the antimicrobial and anticancer activities of methanol and ethyl acetate extracts of calli after UV-C application. Leaf, petiole, and root parts of A. officinalis plants germinated in a sterile environment were used as explant sources. Explants were cultured on MS medium containing different concentrations of 2,4-D (1, 2 mg/l) and BAP (0.25, 0.50, 0.75 mg/l). The most effective (100%) callus growth and callus weight (516.24±0.48 mg) was observed on petiole explants using MS medium containing 1 mg/l 2,4-D + 0.25 mg/l BAP. Calli obtained from leaf and petiole explants were exposed to UV-C treatment. Extractions of calli were carried out using methanol and ethyl acetate solutions. 1 mg/ml, 5 mg/ml, and 10 mg/ml solutions of methanol and ethyl acetate extracts were prepared and their antimicrobial activity on bacteria was investigated using the disc diffusion method for 7 different gram-positive and 9 different gram-negative bacteria. None of the three extract concentrations used had any antimicrobial activities. The anticancer activities of the extracts on SH-SY5Y human neuroblastoma cells were studied using the WST-1 viability kit. 1000, 500, 250, 125, and 62.5 µg/ml concentrations of ethyl acetate extracts of leaf and petiole calli had anticancer activity.

Is UV-C light compatible with biological control of twospotted spider mite?

Biological control agents such as predatory mites, Neoseiulus cucumeris Oudemans, Amblyseius swirskii Athias-Henriot, and Phytoseiulus persimilis Athias-Henriot are effective in the management of a cosmopolitan crop pest, Tetranychus urticae Koch. Studies have shown that physical control by ultraviolet B (UV-B, 280–315 nm) light applications can control T. urticae by reducing egg hatch. However, to have a successful biological control program, the compatibility with other crop management strategies such as use of UV light needs to be determined. Therefore, the objectives of this study were to, 1) assess the impact of UV-C (200–280 nm) application on egg hatchability of biological control agents, A. swirskii, N. cucumeris, P. persimilis, and the pest T. urticae; 2) assess the impact of UV-C application on feeding efficiency of P. persimilis on T. urticae eggs; and 3) determine the LD50 and LD90 of adult female T. urticae to UV-C exposure. Results indicate that more eggs of A. swirskii survived when 200 J/m2 UV-C was used to control T. urticae, which suffered higher egg loss from the same UV-C dose. Also, UV-C treatments of 200 and 350 J/m2 did not have a significant impact on predation by P. persimilis adult females on T. urticae eggs. Therefore, UV-C can be compatibly utilized along with biological control of T. urticae by timing the application before release of predators. After 24 h of application, the UV-C LD50 for T. urticae adults was 8,839.35 J/m2 and the LD90 was 12,352.91 J/m2. After 48 h of application, the LD50 was 7,449.81 J/m2 and the LD90 was 9,621.83 J/m2. These UV-C doses are not feasible for T. urticae adult suppression, but biological control agents can play a crucial role with effective predation on T. urticae adults.

Effects of Nighttime Applications of Germicidal Ultraviolet Light upon Powdery Mildew (Erysiphe necator), Downy Mildew (Plasmopara viticola), and Sour Rot of Grapevine.

Nighttime applications of germicidal ultraviolet were evaluated as a means to suppress three diseases of grapevine. In laboratory studies, UV-C light (peak 254 nm, FWHM 5 nm) applied during darkness strongly inhibited the germination of conidia of Erysphe necator, and at a dose of 200 J/m2 germination was nil. Reciprocity of irradiance and duration of exposure with respect to conidial germination was confirmed for UV-C doses between 0 and 200 J/m2 applied at 4 or 400 seconds. When detached grapevine leaves were exposed during darkness to UV-C at 100 J/m2 up to 7 days before they were inoculated with zoospores of Plasmopara viticola, infection and subsequent sporulation was reduced by over 70% compared to untreated control leaves, indicating an indirect suppression of the pathogen exerted through the host. A hemicylindrical array of low-pressure discharge UV-C lamps configured for trellised grapevines was designed and fitted to both a tractor-drawn carriage and a fully autonomous robotic carriage for vineyard applications. In 2019, in a Chardonnay research vineyard with a history of high inoculum and severe disease, weekly nighttime applications of UV-C suppressed E. necator on leaves and fruit at doses of 100 and 200 J/m2. In the same vineyard in 2020, UV-C was applied once or twice weekly at doses of 70, 100, or 200 J/m2, and severity of E. necator on both leaves and fruit was significantly reduced compared to untreated controls, and twice-weekly applications at 200 J/m2 provided suppression equivalent to a standard fungicide program. None of the foregoing UV-C treatments significantly reduced the severity of P. viticola on Chardonnay vines compared to the untreated control in 2020. However, twice-weekly applications of UV-C at 200 J/m2 to the more downy mildew-resistant Vitis interspecific hybrid cultivar Vignoles in 2021 significantly suppressed foliar disease severity. In commercial Chardonnay vineyards with histories of excellent disease control in Dresden, NY, E. necator remained at trace levels on foliage and was nil on fruit following weekly nighttime applications of UV-C at 200 J/m2 in 2020, and after weekly or twice-weekly application of UV-C at 100 or 200 J/m2 in 2021. In 2019, weekly nighttime applications of UV-C at 200 J/m2 also significantly reduced the severity of sour rot, a decay syndrome of complex etiology, on fruit of the Vitis interspecific hybrid cultivar 'Vignoles', but not the severity of bunch rot caused by Botrytis cinerea. A similar level of suppression of sour rot was observed on Vignoles vines treated twice-weekly with UV-C at 200 J/m2 in 2021. Nighttime UV-C applications did not produce detectable indications of metabolic abnormalities, phytotoxicity, growth reduction, or reductions of fruit yield or quality parameters, even at the highest doses and most frequent intervals employed.

Changes in phenolics and flavonoids in amaranth and soybean sprouts after UV-C treatment.

Sprouts, mainly from cereals, legumes, and some pseudo-cereals, are rich in nutrients and contain biocompounds, making them attractive for consumption. This research study aimed to develop treatments with UV-C light in soybean and amaranth sprouts and evaluate their effect on biocompounds content, compared with chlorine treatments. UV-C treatments were applied at distances of 3 and 5cm and times of 2.5, 5, 10, 15, 20, and 30min, whereas chlorine treatments were applied as immersion in solutions at 100 and 200ppm for 15min. Phenolics and flavonoid content were higher in UV-C-treated sprouts than in those treated with chlorine solutions. Ten biocompounds were identified in soybean sprouts, with increasing in apigenin C-glucoside-rhamnoside (105%), apigenin 7-O-glucosylglucoside (237%), and apigenin C-glucoside malonylated (70%) due to UV-C application (3cm, 15min); for amaranth sprouts, five biocompounds were identified, with higher contents of p-coumaroylquinic acid (17.7%) after UV-C treatment (3cm, 15min). The best treatment to achieve the highest bioactive compounds concentration was UV-C at a distance of 3cm for 15min, without significant modification on the color parameters, Hue and chroma. PRACTICAL APPLICATION: UV-C can be used to increase the biocompound content in amaranth and soybean sprouts. Nowadays, there is UV-C equipment available for industrial applications. In this way, sprouts may be maintained as fresh through this physical technology, and they will retain or increase the concentration of health-related compounds.

UV-C treatment: A non-thermal inactivation method for microbiological stabilisation of must and wine

UV-C treatment is discussed as an effective and efficient method to inactivate harmful microorganisms in wine and other viticultural products. In comparison to other stabilisation techniques, the application of UV-C is thought to be beneficial to reduce energy costs and to minimize SO2 addition. The object of this work was to determine the lethal UV-C dose for harmful microorganisms such as Brettanomyces bruxellensis and Acetobacter aceti. The concept of 5-log inactivation was applied and the Weibull model was used to compare different microbial and wine parameters. Microbial relevant UV-C doses and 2-fold overdose treatments and how they affected chemical and sensory changes of wine were investigated. Riesling and Pinot noir wine, which have different absorbance at 254 nm, were individually inoculated with microorganisms at different inoculation numbers. The results showed that the Weibull model is appropriate to predict the lethal UV-C dose. Already at microbially relevant doses, UV-C treatment can lead to significant changes in the colour and concentration of aroma compounds in white wine. Higher concentrations of 2-aminoacetophenone were found with increasing UV-C doses. Hence, UV-C overdosing can cause the “atypical ageing” off-flavour in wine. However, microbially relevant UV-C doses change the sensory properties of wine more towards a typical ageing character.

Effect of UV-C light on fungi causing root rot/wilt of sage (Salvia offecialis L.)

One of the most significant ornamental, medicinal plants in the world is sage (Salvia offecialis L.). It is susceptible to a wide range of diseases, including root rot brought on by pathogens including Macrophomina phaseoli, Rhizoctonia solani, Fusarium solani, and others that have been identified by multiple studies. Due to the non-traditional nature of the crop, root rot is a serious disease that results in significant loss and little is known about the relationship between the pathogen(s) and its management. Therefore, the current inquiry was conducted to identify the pathogen(s) responsible for the root rot/wilt symptoms and to test if UV-C application may be used to treat this disease. It has been shown that the disease is spread throughout all trial fields in the several districts of the Minia Governorate. Twenty three isolates of fungi, belonging to seven different genera, were obtained from naturally infected samples of sage. The most dominant fungi were Fusarium solani, M. phasiolina, Rhizoctonia solani, which have proved their ability to infect sage plants inducing root rot/ wilt symptoms. The mycelial growth of these fungi was reduced gradually when exposed to UV-C radiation, the highest inhibition was recorded when mycelium was exposed to to UV-C radiation for 120 seconds. Immersed cuttings of sage in pre-treated mycelium of these fungi with UV-C led to reduce the percentages of disease incidence and severity. Also, when cuttings of sage were exposed to UV-C for different periods of exposure, the disease incidence and severity were reduced more than mycelial treatment.

Effectiveness of the Field Application of UV-C for Cucumber Downy Mildew Control

There is growing interest in the application of ultraviolet (UV-C) energy to control crop pathogens. In the present study, the efficacies of UV-C treatments for controlling cucumber downy mildew (Pseudoperonospora cubensis) were investigated on a commercial farm in eastern Massachusetts, USA. Controlled doses of UV-C, delivered by a tractor-mounted array of sources, between 120 and 480 J·m-2 were applied and compared to conventional fungicide treatments as well as to untreated controls, for each of two consecutive years (2020 and 2021). Visual assessments of foliar disease severity in the trial plots were made several times from planting through the end of productive life. In contrast to the successful control of powdery mildew, the UV-C treatments for controlling cucumber downy mildew were not as successful as conventional fungicides. None of the UV-C treatments affected the overall progression rate of downy mildew once the disease became apparent, although disease onset was delayed slightly compared to untreated controls. This delay may have been due to UV-C induced resistance to infection by the host. Unlike powdery mildews, downy mildew spores from P. cubensis are darkly pigmented, possibly decreasing the efficacy of the UV-C treatments for controlling the disease. DM spores may also be only susceptible to UV exposure prior to encysting in the leaves of the host, thereby perhaps limiting the window of opportunity when UV-C treatments can be effective. Although not the primary focus of this study, the use of reflective mulch appeared to delay disease onset relative to black mulch in fields with significant sunlight exposure, perhaps due to lowering plant stress by maintaining a lower soil temperature.

Pollution free UV-C radiation to mitigate COVID-19 transmission

The high rate of transmission of the COVID-19 virus has brought various types of disinfection techniques, for instance, hydrogen peroxide vaporization, microwave generating steam, UV radiation, and dry heating, etc. to prevent the further transmission of the virus. The chemical-based techniques are predominantly used for sanitization of hands, buildings, hospitals, etc. However, these chemicals may affect the health of humans and the environment in unexplored aspects. Furthermore, the UV lamp-based radiation sanitization technique had been applied but has not gained larger acceptability owing to its limitation to penetrate different materials. Therefore, the optical properties of materials are especially important for the utilization of UV light on such disinfection applications. The germicidal or microorganism inactivation application of UV-C has only been in-use in a closed chamber, due to its harmful effect on human skin and the eye. However, it is essential to optimize UV for its use in an open environment for a larger benefit to mitigate the virus spread. In view of this, far UV-C (222 nm) based technology has emerged as a potential option for the sanitization in open areas and degradation of microorganisms present in aerosol during the working conditions. Hence, in the present review article, efforts have been made to evaluate the technical aspects of UV (under the different spectrum and wavelength ranges) and the control of COVID 19 virus spread in the atmosphere including the possibilities of the human body sanitization in working condition.

Smartphone-based miniaturized, green and rapid methods for the colorimetric determination of sugar in soft drinks

Total sugar content of soft drinks was determined in a 3D-printed chamber equipped with an USB camera attached to the smartphone to take pictures directly from the vessels used for the reaction of monosaccharides with cupric ion from Benedict's reagent. The freely available PhotoMetrix UVC application was used to control the device and process images. Reaction time, total volume of solution and illumination were evaluated. Images were captured before and after centrifugation and the results were compared with official method (AOAC 923.09, Lane-Eynon titration). Partial least squares calibration was used reaching suitable values (R2 above 0.99; Root mean square error of calibration (RMSEC) and Root mean square error in cross-validation (RMSECV) values lower than 0.07 and 0.23 mg mL−1, respectively). The proposed methods presented agreements from 95.3 to 108.7% to the official one. Hundreds of samples can be analyzed in one hour and reductions in energy expenditure by 5.5 times and waste volume by 78 times were obtained in relation to the AOAC method.

Effect of UV-C Irradiation on the Shelf-Life of Fresh-Cut Potato and Its Sensory Properties after Cooking

SUMMARYResearch backgroundPotato tissue is damaged during fresh-cut production, which makes fresh-cut potato susceptible to the quality loss and microbiological spoilage. At the same time, such products are desirable due to their convenience; however, they are extremely sensitive and have short shelf life. The main challenge of the fresh-cut potato industry is to find possibilities to overcome these drawbacks. UV-C treatment, known for its antibacterial activity, is a promising technique and it shows a potential to improve shelf life of fresh-cut potato products.Experimental approachThe influence of the UV-C treatment on the safety and quality, as well as sensory traits of fresh-cut potato (Solanum tuberosum L. cv. Birgit) during storage was examined. For this purpose, 0-, 3-, 5- and 10-min UV-C irradiation was applied on vacuum-packed potato slices pretreated with sodium ascorbate solution. During 23 days of storage at (6±1) °C, microbiological, physicochemical and sensory properties of raw samples were monitored, along with sensory properties of boiled and fried fresh-cut potatoes.Results and conclusionsThe 5- and 10-min UV-C treatments significantly reduced microbial growth, increased total solids and lightness (L*), and positively affected odour and firmness of raw potatoes. Cooked UV-C-treated samples were described with more pronounced characteristic potato odour and taste. Overall, UV-C-treated fresh-cut potato retained its good quality and sensory traits up to 15 days at (6±1) °C.Novelty and scientific contributionTo the best of our knowledge, this is the first scientific article dealing with the effect of UV-C light on durability (safety, quality and sensory traits) of fresh-cut potato cv. Birgit and its suitability for boiling and frying. In general, UV-C treatment is a known antimicrobial technique, but its application on fresh-cut potato is poorly explored. Results confirmed that vacuum-packed fresh-cut potato treated only with UV-C and sodium ascorbate as anti-browning agent, without the addition of chemical preservatives, had twofold longer shelf-life at (6±1) °C than the fresh-cut potato not treated with UV-C. Fresh-cut potato treated with UV-C retained good overall quality and sensory properties either raw, boiled or fried. Results of this study could also be useful for producers in terms of potential UV-C application as a strategy for prolonging the shelf-life of fresh-cut potato.

Germination of Bacillus cereus ATCC 14579 spore at various conditions and inactivation of the germinated cells with microwave heating and UVC treatment in milk samples

In this study, germination of Bacillus cereus spores under various conditions and the inactivation of germinated cells by microwave heating (MH) and 254 nm ultraviolet (UVC) treatment in milk samples were identified. A combination of germinants, ʟ-alanine and inosine, was the most effective for germination of B. cereus spores; and heat activation during the germination step increased the germination rate to 99.98% at pH 7 with 1% sodium chloride. The resistances of germinated cells by optimized conditions, inoculated in milk samples, to MH and UVC were investigated. The reduction rate was the highest in skimmed milk followed by low-fat and whole milk samples. The resistance of germinated cells was significantly higher than that of the vegetative cells regardless of the milk type. Sequential treatments exhibited a higher reduction rate than the sum of individual treatments, and resuscitation of germinated cells was not observed even after the longest treatment. Moreover, the quality aspects of milk samples were not significantly deteriorated (p > 0.05) except for the pH values which were found to be slightly decreased. These results would be used as a fundamental database for the application of UVC and MH to inactivate B. cereus spores in milk samples.

Investigation of the Disinfection Effect of Some Environmental Friendly Applications on Cotton Fabrics

ABSTRACT Today, the importance of health is kept on top of many things. Because people understood that neither the money they earn nor the life they live without their health is of any importance. Textile materials are together in every field during the day with us and they can be exposed to the attacks of microorganisms quite easily. Hence, ways of getting rid of these attacks in easy and environmental approaches should be considered in most cases. In this context, disinfection processes of textile products were investigated in this study. For this aim cotton fabrics were contaminated separately with two different types of bacteria. These bacterial species are Staphylococcus aureus (ATCC 29,213) and Escherichia coli (ATCC 25,922). Then bacterial contaminated fabric samples were treated with ozone and UV-C for different periods of time by a set of ozone and UV-C application system. Additionally hydrogen peroxide based disinfection has been tested as well. After these processes, bacterial reduction tests were carried out. In addition, SEM images of some fabric samples were taken to observe the surface modification. As a result, it was found that necessary and sufficient disinfection effect was obtained on cotton fabric in very short application time by using especially ozone gas.

Prevention of decay and maintenance of bioactive compounds in strawberry by application of UV-C and essential oils

Prevention of decay and maintenance of bioactive compounds in strawberry by application of UV-C and essential oils

Dual-wavelength ultraviolet photodetector based on vertical (Al,Ga)N nanowires and graphene* *Project supported by the National Key Research and Development Program of China (Grant No. 2018YFB0406602), Natural Science Foundation of Jiangsu Province, China (Grant No. BK20180252), Key Research Program of Frontier Sciences, CAS (Grant No. ZDBS-LY-JSC034), the National Natural Science Foundation of China (Grant Nos. 61804163, 61875224, and 61827823), the Key

Due to the wide application of UV-A (320 nm–400 nm) and UV-C (200 nm–280 nm) photodetectors, dual-wavelength (UV-A/UV-C) photodetectors are promising for future markets. A dual-wavelength UV photodetector based on vertical (Al,Ga)N nanowires and graphene has been demonstrated successfully, in which graphene is used as a transparent electrode. Both UV-A and UV-C responses can be clearly detected by the device, and the rejection ratio (R 254 nm/R 450 nm) exceeds 35 times at an applied bias of –2 V. The short response time of the device is less than 20 ms. Furthermore, the underlying mechanism of double ultraviolet responses has also been analyzed systematically. The dual-wavelength detections could mainly result from the appropriate ratio of the thicknesses and the enough energy band difference of (Al,Ga)N and GaN sections.