Ozone Gas Research Articles

Enhanced ozone gas detection with Sb doped ZnO nanorods synthesized on MEMS microheater

Metal oxide semiconductors infused with noble metals or metalloids are studied and employed in semiconductor sensors applications to a greater extent. In this study, antimony (Sb) is doped with ZnO in 4 different concentrations to compare the optimal parameters in gas sensing properties. Sb/ZnO nanostructure is synthesized by hydrothermal process and deposited on MEMS (Micro electro mechanical system) microheater device. The morphology of the nanostructure is analyzed for planar structure, oxidation states and the presence of Sb/ZnO is successfully verified. Ozone is a powerful oxidizing gas which is a health hazard in public places, so low concentrations of ozone is tested with Sb/ZnO sensor at various parameters. Since Sb acts as catalyst to promote the gas sensing properties, the sensor responses have been enhanced compared to pure ZnO sensor. Sensor performed its best at 200 °C and has the lowest detection gas concentration of 10 ppb. Sb/ZnO showed good selectivity over ozone gas.

Quality attributes of oil extracted from hazelnuts treated with gaseous ozone

In this study, the impact of ozonation on hazelnut oil quality was investigated. Hazelnuts were exposed to gaseous ozone at different concentrations (3.3 and 10 mg·L−1) and exposure times (30, 60, and 120 min). The fatty acid value and composition remained unchanged. β-sitosterol, campesterol, and ∆5-avenasterol contents were unaffected. With increasing ozone levels and exposure times, there was a slight rise in peroxide value and γ-tocopherol, and a decrease in α-tocopherol. The total phenolic content and antioxidant activity were lower in oil extracted from hazelnuts which had been ozonated for more than 60 min at both doses, compared to the control. Overall, the quality and composition of hazelnut oil remained stable with ozone treatments, depending on the treatment conditions.

Examining the Proliferative Effect of Ozonated Olive Oil and Ozonated Distilled Water on Healthy Colon Fibroblast Cells and Colon Cancer Cells

Ozone therapy is an alternative form of treatment based on the administration of ozone gas to the body in the treatment of diseases and different medical conditions, and ozone applications are recommended in some studies. In this study, it was aimed to determine the possible anti-cancer activity by enriching extra virgin olive oil and distilled water with ozone gas and determining its cytotoxic effect on colon cancer and normal colon fibroblast cells. The effect of ozone enriched extra virgin olive oil and distilled water on cell viability was determined by MTT assay on DLD1 (colon cancer) and CCD-18Co (healthy colon fibroblast) cell lines. In the DLD-1 cell line, ozonated distilled water and olive oil decreased in vitro cell viability at all concentrations and this decrease was most pronounced at higher concentrations (5 and 10 ppm). In the CCD-18Co cell line, ozonized distilled water and ozonized olive oil increased in vitro cell viability at all concentrations, but this increase was not significant compared to the control. The results of this study are consistent with the results of other studies in the literature. Therefore, ozone therapy is thought to be promising in cancer treatment.

Environmentally Friendly Bleaching Process of the Cellulose Fibres Materials Using Ozone and Hydrogen Peroxide in the Gas Phase.

The paper presents the new eco-friendly method of bleaching process of the cellulose fibre materials. Cellulose materials were bleached using hydrogen peroxide (both in aqueous solution, vapours, ozone and by the combined action of gaseous hydrogen peroxide and ozone. The method using hydrogen peroxide in aqueous solution presents the standard procedure and was used as the comparison technique. The bleaching processes using gaseous oxidants were carried out in a prototype device for dry, low-temperature treatment of fibrous materials with the use of oxidising agents in the gas phase. The influence of the innovative gas-phase bleaching method on the cotton samples' properties was analysed by Scanning Electron Microscopy (SEM), evaluation of the colour and whiteness, assessment of the polymerisation degree (DP), analysis of the mechanical properties and sorption capacity as well as microbiological assessment against colonies of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The comparison of the obtained results led to the conclusion that the bleaching processes using gas-phase agents-vaporised hydrogen peroxide, ozone or their combination-are non-invasive. The applied bleaching processes resulted in a slightly lower whiteness parameters than standard bath bleaching. After the bleaching processes with ozone and vaporised hydrogen peroxide separately, the decrease in the DP and tensile strength was similar to that observed after the bleaching with aqueous H2O2. When both processes were used together, a higher reduction in DP and tensile strength was noticed. Both oxidising agents showed a strong biocidal effect against bacteria. Gas-phase bleaching procedures, due to the lower temperature (35 °C vs. 98 °C) and minimal water consumption, have economic and environmental advantages, which allows their use in semi-industrial applications. It has been shown that the treatment of cotton fabrics using ozone and hydrogen peroxide in the gas phase allows to simultaneously obtain the bleaching and disinfection effect.

Self-Powered InGaZnO Ozone Gas Sensors Based on a Metal–Semiconductor–Metal Structure with Asymmetric Interdigitated Electrodes

Self-Powered InGaZnO Ozone Gas Sensors Based on a Metal–Semiconductor–Metal Structure with Asymmetric Interdigitated Electrodes

THE COMPARISON OF OXIDATION EFFICIENCY OF REACTIVE OXYGEN SPECIES (ROS): PILOT SCALE OF MICROBUBBLE TECHNOLOGIES WITH OXYGEN CONCENTRATION

The objective of this study is to assess and compare the effectiveness of an oxidizing agent. Within the field of advanced oxidation processes (AOPs), ozone, a highly reactive gas, generates reactive oxygen species (ROS) as byproducts through chemical reactions. The study employed a dielectric barrier discharge (DBD) plasma generator to produce ozone gas. This study was carried out under different gas source conditions, including both air and oxygen. Additionally, the ROS produced as byproducts from the interaction between ozone gas and water were measured using oxidation-reduction potential (ORP) values. The ORP values exhibit strong foundational attributes for both ozone dissolution and ROS oxidation efficiency. To extend the interaction duration between ozone gas and water, a stone diffuser was utilized to introduce ozone gas into the water. This mechanism resulted in the creation of ozone microbubbles through a process known as cavitation. The results illustrate a positive relationship between the flow rate and ozone yield. This trend reached its highpoint with the highest observed ozone concentrations approximately 14.11 mg/L for oxygen and 4.55 mg/L for air both achieved at a flow rate of 11 L/min. Furthermore, the highest ozone concentrations were recorded at 15.17 mg/L for oxygen and 12.59 mg/L for air after a 10 min discharge period. Interestingly, ozone generated from oxygen feed gas exhibited a higher concentration yield than that from air feed gas. Moreover, the ORP value displayed a continuous increase with longer treatment times, eventually stabilizing at around the 15 min. This pattern corresponded to the water reaching its highest the ORP values approximately 821 mV for oxygen and 569 mV for air. In summary, this study emphasizes the potential benefits of utilizing ozone as an effective oxidant in both gaseous (ozone gas) and liquid (ROS) phases. It especially emphasizes the essential role played by the generation of ozone and ROS from an oxygen-fed gas source. Moreover, it highlights the significance of maintaining an optimal flow rate of 11 L/min and a discharge duration of 10 min for achieving the highest ozone concentration. Similarly, a treatment time of 15 min for the liquid phase is recommended to maximize ORP values. Both of these values indicate the highest potential advantages for producing an effective oxidant.

Ozone Treatment for the Management of Caries in Primary Dentition: A Systematic Review of Clinical Studies.

Dental caries in children is a frequent and debilitating condition, whose management is often challenging. The aim of this systematic review was to investigate the effectiveness of ozone applications for the treatment of caries in primary dentition. According to PRISMA guidelines, a systematic literature search was performed up to 6 January 2024. Clinical studies using ozone to treat caries of deciduous teeth were considered for inclusion. Out of the 215 records retrieved, seven studies were eventually included in the review, all of which used gaseous ozone. Four studies were judged at high risk of bias, two at low risk, and one of some concerns. The great heterogeneity of designs, outcomes, and protocols made it impossible to conduct a meta-analysis. Despite some limitations, the evidence yielded by the included studies suggests that ozone application, regardless of the protocol applied, is comparable to other interventions in terms of clinical outcomes and anti-bacterial activity, with no reported adverse effects and good patient acceptance. Therefore, ozone application may be a non-invasive approach to treat caries in primary dentition, especially in very young and poorly cooperative patients. Further standardized and rigorous studies are, however, needed to identify the best clinical protocols for this specific field.

Potential of gaseous ozone to inhibit Aspergillus flavus and detoxify aflatoxin B1 in agar and broth media (solid and liquid food states) at different growth phases

Agricultural food crops are prone to Aspergillus flavus contamination during post-harvest and storage stages. Their consumption is toxic due to aflatoxin production, a potent carcinogenic and immunosuppressive agent. Present study explored the ozone's effect as a function of food media states (solid and liquid) to inhibit Aspergillus flavus under three modes of treatment (0th-day, Every-day and Nth-day ozone treatment), that adds novelty to the work. Results showed that ozone concentration to treat Aspergillus flavus and aflatoxins is higher in liquid than solid food state. Further, ozone treatment affected the intactness of fungal spores and inhibited 100% conidial growth. It also exhibited 88 %% inhibition and 90% reduced biomass in solid and liquid food states. Effectiveness of ozone towards inhibiting Aspergillus flavus and aflatoxin was in the following order: Nth -day treatment > Every-day treatment > 0th -day ozone treatment. Further, growth studies showed ozone treated cultures exhibit delayed sporulation and aflatoxin production by 72 h. when cultured on fresh media. Additionally, ozone purging into extracted aflatoxin led to > 99% degradation. The above results show the significance of ozone technology in increasing the shelf-life of post-harvested food crops. Further, it can be used as a disinfectant in the food industry to treat contaminated food crops/liquid products by detoxifying aflatoxins.

On the potential use of highly oxygenated organic molecules (HOMs) as indicators for ozone formation sensitivity

Abstract. Ozone (O3), an important and ubiquitous trace gas, protects lives from harmful solar ultraviolet (UV) radiation in the stratosphere but is toxic to living organisms in the troposphere. Additionally, tropospheric O3 is a key oxidant and a source of other oxidants (e.g., OH and NO3 radicals) for various volatile organic compounds (VOCs). Recently, highly oxygenated organic molecules (HOMs) were identified as a new compound group formed from the oxidation of many VOCs, making up a significant source of secondary organic aerosol (SOA). The pathways forming HOMs from VOCs involve autoxidation of peroxy radicals (RO2), formed ubiquitously in many VOC oxidation reactions. The main sink for RO2 is bimolecular reactions with other radicals, such as HO2, NO, or other RO2, and this largely determines the structure of the end products. Organic nitrates form solely from RO2 + NO reactions, while accretion products (“dimers”) form solely from RO2 + RO2 reactions. The RO2 + NO reaction also converts NO into NO2, making it a net source for O3 through NO2 photolysis. There is a highly nonlinear relationship between O3, NOx, and VOCs. Understanding the O3 formation sensitivity to changes in VOCs and NOx is crucial for making optimal mitigation policies to control O3 concentrations. However, determining the specific O3 formation regimes (either VOC-limited or NOx-limited) remains challenging in diverse environmental conditions. In this work we assessed whether HOM measurements can function as a real-time indicator for the O3 formation sensitivity based on the hypothesis that HOM compositions can describe the relative importance of NO as a terminator for RO2. Given the fast formation and short lifetimes of low-volatility HOMs (timescale of minutes), they describe the instantaneous chemical regime of the atmosphere. In this work, we conducted a series of monoterpene oxidation experiments in our chamber while varying the concentrations of NOx and VOCs under different NO2 photolysis rates. We also measured the relative concentrations of HOMs of different types (dimers, nitrate-containing monomers, and non-nitrate monomers) and used ratios between these to estimate the O3 formation sensitivity. We find that for this simple system, the O3 sensitivity could be described very well based on the HOM measurements. Future work will focus on determining to what extent this approach can be applied in more complex atmospheric environments. Ambient measurements of HOMs have become increasingly common during the last decade, and therefore we expect that there are already a large number of groups with available data for testing this approach.

Performance evaluation and optimization of a suspension-type reactor for use in heterogeneous catalytic ozonation

Packed fixed-bed reactors are traditionally used for heterogeneous catalytic ozonation. However, a high solid-to-liquid requirement, poor ozone dissolution, ineffective utilization of catalyst surface area, and production of large amounts of catalyst waste impede application of such reactors. In this study, we designed a suspension catalytic ozonation reactor and compared the performance of this reactor with that of a traditional fixed-bed catalytic ozonation reactor employing oxalic acid (OA) as the target contaminant. Our results showed that total O3 dissolved into the suspension reactor (117–134 mg.L−1) was much higher compared to that measured in the fixed-bed reactor (53 mg.L−1) due to a higher O3(g) interphase mass transfer rate in the suspension reactor. In accordance with the higher O3(g) interphase mass transfer, we observed a much higher proportional OA removal (32 %) compared to that achieved in the fixed-bed reactor (10%) employing an Fe-oxide catalyst supported on Al2O3 (Fe-oxide@Al2O3) in both reactors. Use of a double-layered Cu-Al hydroxide (Cu-Al LDHs) catalyst in the suspension reactor further enhanced the performance with nearly 90 % OA removal observed. Given the superior performance of the suspension reactor, we investigated the impact of operating conditions (catalyst dosage, hydraulic retention time and ozone dosage) employing Cu-Al LDHs as the catalyst. We also developed a mathematical kinetic model to describe the performance of the suspension reactor and, through use of the kinetic model, showed that O3(g) interphase transfer rate was the rate-limiting step in OA removal. Thus, improvement in ozone gas diffuser design is required to improve the performance of the suspension reactor. Overall, the present study demonstrated that suspension reactors were more effective than fixed-bed reactors for oxidation of surface-active organic compounds such as OA due to the higher ozone interphase mass transfer rate and effective utilization of the catalyst surface area that can be achieved. As such, further research on suspension reactor design and development of catalysts suitable for use in suspension reactors should facilitate large-scale application of catalytic ozonation processes by the wastewater treatment industry.

Can Nanobubble Ozone Liposomes Be A New Agent In The Fight Against Foodborne Infections?

In this study, a nanobubble ozone liposome solution containing 2% ZnCl2 was used. The aging tests were conducted according to the ASTM F 1980 [1] standards. The minimum inhibitory concentration (MIC) level of the nanobubble ozone liposome solution with 2% ZnCl2 was determined as 1.562 ppm for strains of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) by the CLSI M07 A9 [2] standard test method. To assess the time-dependent antibacterial effect of the nanobubble liposome solution with 2% ZnCl2, the solution's efficiency at a concentration of 2000 ppm and for different time intervals was tested on strains of Salmonella enterica subsp. enterica (ATCC® 14028™) and Listeria monocytogenes (ATCC® 7644™). The results showed that the antibacterial activity of the strains of S. enterica subsp. enterica started at the end of the 10th minute and the solution was effective after 30 minutes. For strains of L. monocytogenes, it was observed that the activity started at the end of the 2nd minute and the product was effective after the 10th minute. According to the ASTM F 1980 standards, it was found that the nanobubble ozone liposome solution retained its effectiveness in one-year stability tests. As a result, the nanoparticle liposome solution, a new product, does not lose its stability and effectiveness for a long time, contrary to what is known. Although the half-life of gaseous ozone is as short as 20 minutes, the stability in the nanoparticle liposome solution has been determined as at least one year. Since nanoparticle liposome solution is a natural and slow-release product, nanobubble ozone liposome solution with 2% ZnCl2 may be used as a newly developed agent against contaminations in food processing facilities caused by biofilm-forming microorganisms through the use in disinfections of surfaces that are in direct contact with food products.

Efficacy of Ozone Gas on the Greater Wax Moth, Galleria mellonella Larvae

Efficacy of Ozone Gas on the Greater Wax Moth, Galleria mellonella Larvae

Modeling of tubular membrane contactors for ozonation of water reveals reduced bromate formation with static mixers

Bromate formation and insufficient micropollutant degradation are two major problems in wastewater ozonation. The conventional process using bubble columns has the drawback of an inhomogeneous ozone distribution, causing increased bromate formation. Membrane contactors are a promising alternative as they can dissolve ozone bubble-free. This work presents a simulation of a tubular membrane contactor in COMSOL Multiphysics that includes flow, mass transfer, ozone decay, and reactions of organic molecules and bromide with ozone and hydroxyl radicals. Gaseous ozone and water flow on the lumen and shell side of the membrane, respectively. Static mixers are placed in the water channel, coaxial between the membrane and housing. The simulations show a 75% increase in ozone flux through the membrane, a homogenized ozone distribution, and 13 times higher degradation of a medium-oxidizable micropollutant in the presence of additional static mixers. Furthermore, static mixers enable the use of a lower gaseous ozone concentration, resulting in 31% lower bromate formation at the same ozone exposure without affecting micropollutant degradation. Overall, we demonstrate that membrane contactors with static mixers can be used as a strategy to reduce bromate formation.

Efficacy of Intra-Articular Ozone Versus Hyaluronic Acid In Patients of Knee Osteoarthritis

Objective: To determine the analgesic efficacy of ozone gas versus hyaluronic acid solution in knee osteoarthritis patients. Study Design: Quasi-experimental study. Place and duration of study: Department of Pain Medicine, Combined Military Hospital, Rawalpindi Pakistan, from Jun to Dec 2020. Methodology: Seventy patients suffering from knee osteoarthritis fulfilling the inclusion criteria were included in this study and were randomly assigned to two equal groups to undergo intra-articular knee injection using either Hyaluronic Acid (Group-H) or Ozone (Group-O). Improvement in the numeric rating scale (NRS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale were recorded 1, 3 and 6 months after the procedure. Results: In both groups, the pain score (Group-H Pre-procedure NRS =7.66±0.87 vs. Post-Procedure 6 month NRS = 4.74±0.70, Group-O Pre-procedure NRS = 7.86±0.88 vs. Post-Procedure 6 month NRS = 4.46±0.92) and WOMAC (Group-H Pre-procedure =77.60±7.93 vs. Post-Procedure 6 month =40.31±6.81, Group-O Pre-procedure=75.54±9.40 vs. Post-Procedure 6 month =38.37±8.98) score improved. However, the NRS pain score (p-value = 0.21) and patient WOMAC score (p-value = 0.31) were not significantly different between groups. Conclusion: Neither Hyaluronic Acid nor Ozone appears superior in decreasing pain scores or physical limitations, particularly for knee osteoarthritis.

Ozone and Laser Effects on Dentin Hypersensitivity Treatment: A Randomized Clinical Study

IntroductionThe aim of this study was to evaluate and compare the clinical efficacy of diode laser and ozone gas in the treatment of dentin hypersensitivity (DHS). MethodsOne hundred thirty-two teeth from 44 patients with moderate DHS were randomized into 3 groups according to a split-mouth design. In the diode laser group, the operator irradiated the superficial dentin exposed with an 808-nm wavelength and incremental power from 0.2 to 0.6 W with a 20-second interval. In the ozone gas group, the operator applied a high dose of ozone (32 g/m3) for 30 seconds using a silicon cup. In the placebo group, no therapy was applied. The dentin sensitivity level was evaluated upon enrollment (T0), immediately after treatment (T1), 3 months post-treatment (T2), and 6 months post-treatment (T3) with a cold air blast challenge and tactile stimuli. The pain severity was quantified according to the visual analogue scale. The Wilcoxon signed rank test was used to scrutinize potential statistical disparities among the treatments. Statistical significance was predetermined at P < .05. ResultsA significant decrease of DHS was observed in the ozone gas group and the `diode laser group immediately after treatment and after 3 and 6 months of the therapy. After 6 months from the therapy, the sensitivity values in the teeth treated with ozone gas remained statistically lower than those treated with diode lasers (P < .05). ConclusionsA laser diode and ozone gas are both efficient as dentin sensitivity treatment. Ozone maintains an invariable effectiveness after 6 months.

In vitro effects of different ozone preparations on microorganisms responsible for endometritis in the mare

Infectious endometritis is considered one of the major causes of infertility and it can affect up to 60% of barren mares. It is characterized by the presence of one or more microorganisms in the reproductive tract and it is treated with the administration of antibiotics, ecbolic agents and uterine lavages. Ozone, thanks to its antimicrobial properties that are based on its high oxidative potential, could represent an effective alternative treatment for endometritis. The aim of this study was to test in vitro the bactericidal and fungicidal properties of different ozone formulations, either as gas (experiment 1) or dissolved in two liquid matrices (experiment 2), specifically distilled water or oil (Neozone 4000, Cosmoproject, Parma, Italy), onto 6 different species of microorganisms isolated from mares with clinical endometritis, namely Escherichia coli, Staphylococcus aureus, Streptococcus equi subsp. Zooepidemicus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans. In the first experiment, 3 clinical antibiotic-resistant strains per each species were exposed to different conditions: to O2O3 gas mixtures (15 and 40 μg/ml for 1, 3 and 5 min), to 100 % O2 or left untreated. The results showed a reduction of the microbial count of over 99,9% for every pathogen, time and concentration of O2O3 gas mixtures tested. Furthermore, gaseous ozone showed both a time-dependant effect (5 vs 3 vs 1 min of exposure) and a concentration-dependant effect (40 vs 15 μg/ml) at 1 and 3 min, while after 5 min no differences were observed. In the second experiment, minimum inhibitory concentration (MIC), and minimum bactericidal/fungicidal concentration (MBC, MFC) of ozonated distilled water and ozonated oil were evaluated. Ozonated oil showed a bactericidal/fungicidal activity against all the strains tested (MIC range 12.5–25 % v/v, MBC/MFC range 12.5–50 % v/v) while ozonated distilled water didn't show an observable antimicrobial effect, discouraging its use as an antimicrobial agent for the treatment of endometritis.The results of this in vitro study indicate that both gaseous ozone and ozonated oil exerted remarkable antimicrobial activities and are promising alternative treatments for infectious endometritis, even when caused by antibiotic-resistant bacteria, and encourage further experiments in an effort to scale down or even prevent the use of antibiotics in equine reproduction.

Microbial and Fungal Growth Control and Evaluation of Quality Parameters During Ripening of Toma Piemontese PDO Cheese Treated with Gaseous Ozone

ABSTRACT The cheese ripening period, in which biochemical changes occur under specific temperature and humidity conditions, is crucial for making the finished product marketable. However, the food matrix can become a growth medium for developing spoilage microorganisms and fungi. In dairy factory, contamination of the crust area can be monitored with several wasteful and time-expensive methods, i.e., the use of saline solutions and/or the brushing of cheese wheels. This study investigates the effectiveness of different ozone treatments, 400 ppb, 8 hours (overnight) every other day until the end of ripening, and 300 ppb, 8 hours per day (overnight) for the entire ripening duration compared to control sample in normal atmosphere, in controlling microbial and fungal growth during the ripening of Toma Piemontese PDO cheese. Results showed that ozone treatments significantly affect spoilage microflora, preserving the overall quality parameters (i.e., weight loss, customer value, and greater sensory nuances).

Predicting Ozone Depletion using BIn2O3 With RH based Solid Conductometric Sensor

&lt;p&gt;Ozone depletion arises due to the presence of gases like chlorofluorocarbons and halons which are liberated into the atmosphere. The region of earth’s atmosphere named as ozone shield, in which absorbs the ultra violet radiations of the sun. Although, its thickness varies periodically, this layer is primarily located in the lower stratosphere between 15 to 35 kms above the earth. Due to this, the ultraviolet rays directly enter into the earth causes harmful effects little by little on both living and non-living organisms. In this paper, BIn2O3 with rh sensor in co precipitation method is used to detect the ozone depletion and it is based on the solid-state gas sensors. To achieve the excellent performance of an ozone depletion detecting branch like BIn2O3 with rh, this was designed using a simple precipitation method. The coprecipitation method had deposited in BIn2O3 with a thickness of 45 to 50 nanometer. The detection limit of ozone reduced as 30 parts per billion. Further, the gas detector demonstrated high sensitivity and selectivity of the device. The rhodium covers the surface areas ranges from 0 to 0.1. It reaches the accuracy of 96%. According to the degree of rhodium coverage, the sensors will be response to the ozone gas. The oxygen chemisorbed ability and a coverage of a great surface area of BIn2O3 with rhodium highly related to the excellent sensing behavior. This study paves the way for an exact sensing and ppb level detection ozone gas.&lt;/p&gt;&#x0D;

Sanitizing of stainless steel surfaces in the food industry: Effect of gaseous ozone against pathogens and filamentous fungi

AbstractThe aim of this work was to evaluate the resistance of two pathogenic bacteria (Listeria monocytogenes and Salmonella enterica subsp. enterica serotype Senftenberg), and three airborne food‐spoiling filamentous fungi (Hyphopichia burtonii, Penicillium nordicum, and Aspergillus brasiliensis ATCC 16404) to gaseous ozone on stainless steel. Tests were carried out by exposing inoculated tiles to gaseous ozone in a laboratorial chamber at concentrations up to 50 mg/L and at times up to 180 min (bacteria) or 300 min (filamentous fungi). For bacteria, the resistance to gaseous ozone of L. monocytogenes proved markedly higher than that of S. enterica. Their D‐values increased by seven times (from 27.3 to 200.7 min for the strain of L. monocytogenes studied; from 7.3 to 48.0 min for the Salmonella species studied) when the ozone concentration were reduced from 12 to 4 mg/L. For filamentous fungi, a substantial effect was observed only at 50 mg/L on single‐layered inocula: at these conditions, A. brasiliensis ATCC 16404 proved the most resistant strain to gaseous ozone, its D‐value (134.4 min) being higher than those registered for the tested strains of H. burtonii (9.9 min) and P. nordicum (17.1 min). The results demonstrated that the use of gaseous ozone as a sanitizing agent for environments and working surfaces seems to be a potential alternative to chemical sanitizers against the two pathogens studied, whereas it seemed effective against the three filamentous fungi studied only in limited circumstances.

Efficacy of Ozone, UV Radiation, Herbal and Glutaraldehyde Method for Sterilisation of Elastomeric Impression Materials for Orthodontic and Prosthodontic procedures

ABSTRACT Objectives: The objectives of the current study was to evaluate the disinfection efficacy of ozone, ultraviolet (UV) radiation, herbal and glutaraldehyde method for sterilization of elastomeric impression materials Materials and Methods: Disinfection of elastomeric impression material was performed with each of the disinfection methods: ozone, UV radiation, herbal, and glutaraldehyde. Later microbiological analysis was performed and the colony-forming units were evaluated and compared. Results: The highest disinfection efficacy was found with glutaraldehyde, followed by ozone and UV radiation, and the least with neem herbal rinse. Intergroup comparison was highly significant Conclusion: Dry gaseous ozone and UV radiation can be used effectively for the disinfection of impressions.