Germicidal Properties Research Articles

Non-Thermal Atmospheric Pressure Plasma Application in Endodontics.

The failure of endodontic treatment is frequently associated with the presence of remaining microorganisms, mainly due to the difficulty of eliminating the biofilm and the limitation of conventional irrigation solutions. Non-thermal atmospheric pressure plasma (NTPP) has been suggested for many applications in the medical field and can be applied directly to biological surfaces or indirectly through activated liquids. This literature review aims to evaluate the potential of NTPP application in Endodontics. A search in the databases Lilacs, Pubmed, and Ebsco was performed. Seventeen manuscripts published between 2007 and 2022 that followed our established inclusion criteria were found. The selected manuscripts evaluated the use of NTPP regarding its antimicrobial activity, in the direct exposure and indirect method, i.e., plasma-activated liquid. Of these, 15 used direct exposure. Different parameters, such as working gas and distance from the apparatus to the substrate, were evaluated in vitro and ex vivo. NTPP showed a disinfection property against important endodontic microorganisms, mainly Enterococcus faecalis and Candida albicans. The antimicrobial potential was dependent on plasma exposure time, with the highest antimicrobial effects over eight minutes of exposure. Interestingly, the association of NTPP and conventional antimicrobial solutions, in general, was shown to be more effective than both treatments separately. This association showed antimicrobial results with a short plasma exposure time, what could be interesting in clinical practice. However, considering the lack of standardization of the direct exposure parameters and few studies about plasma-activated liquids, more studies in the area for endodontic purposes are still required.

Personal Care Products as a Contributing Factor to Antimicrobial Resistance: Current State and Novel Approach to Investigation.

Antimicrobial resistance (AMR) is one of the world's industrialized nations' biggest issues. It has a significant influence on the ecosystem and negatively affects human health. The overuse of antibiotics in the healthcare and agri-food industries has historically been defined as a leading factor, although the use of antimicrobial-containing personal care products plays a significant role in the spread of AMR. Lotions, creams, shampoos, soaps, shower gels, toothpaste, fragrances, and other items are used for everyday grooming and hygiene. However, in addition to the primary ingredients, additives are included to help preserve the product by lowering its microbial load and provide disinfection properties. These same substances are released into the environment, escaping traditional wastewater treatment methods and remaining in ecosystems where they contact microbial communities and promote the spread of resistance. The study of antimicrobial compounds, which are often solely researched from a toxicological point of view, must be resumed considering the recent discoveries, to highlight their contribution to AMR. Parabens, triclocarban, and triclosan are among the most worrying chemicals. To investigate this issue, more effective models must be chosen. Among them, zebrafish is a crucial study system because it allows for the assessment of both the risks associated with exposure to these substances as well as environmental monitoring. Furthermore, artificial intelligence-based computer systems are useful in simplifying the handling of antibiotic resistance data and speeding up drug discovery processes.

Surface Disinfection and Sanitizing Action of the Alcohol-Free Essential Oil-based Green Formulation

The surface disinfectant property of a prepared formulation using potential and effective EO (Murraya koenigii), phytochemical (Geraniol), and an amino acid epsilon-L-Poly-Lysine (ɛ-PL) is examined in this present study. To investigate its potential as a surface disinfectant (SD) different tests using multiple bacterial strains were conducted. All tested bacterial strains were inhibited by the SD treatments, with a MIC range of (0.78-3.12%) v/v. Notably, Staphylococcus sp. was found to be more susceptible to the treatment than its gram-negative counterparts. In the test, sterile stainless-steel surfaces were used and externally contaminated with Escherichia sp. Cleaning the surface with the prepared formulation was more effective than the equal concentration of vinegar in terms of bacterial growth reduction. Vinegar was used as a mother solvent in the preparation of the SD due to its proven antibacterial effect. It is worth mentioning, this formulation is also proven to be effective on biofilm-embedded bacterial cells of Pseudomonas aeruginosa PAO1 as found in epifluorescence microscopy staining. Even though the impact of each constituent needs to be further explored, the effectiveness of this formulation may encourage large farms to seek out alternatives that are more environmentally friendly, safe, and effective than conventional products.

Chitosan-based hydrogels obtained via photoinitiated click polymer IPN reaction

Chitosan (CTS) is a polysaccharide with a wide variety of applications in the biomedical field, owing to its outstanding disinfectant properties, biocompatibility and biodegradability, but with limited mechanical properties. The proposed strategy to improve CTS-based hydrogel properties in this study is the formation of a semi-interpenetrating polymer network (semi-IPN). In this way, a photo-initiated radical click reaction was proposed to obtain a synthetic polymer, whose components were included in a CTS solution, resulting in the semi-IPN network after UV illumination. Different crosslinking degrees (CD) and CTS/polymer ratios were evaluated through rheological characterization, along with an assessment of both variables based on an experimental model design, obtaining that, for every CTS/polymer ratio, intermediate values of CD (8 %) offered the best rheological properties. In addition, chemical and microstructural characterization were carried out for selected hydrogels, obtaining consistent results according to rheological characterization, as the 1/1 CTS/polymer ratio with CD 8 % hydrogel displayed the most homogeneous pore size and distribution, consequently leading to the best rheological performance.

Antimicrobial properties of oxygen-active disinfectants

Oxygen-active disinfectants are widely used for the nonspecific prevention of infectious diseases: hydrogen peroxide, chlorine dioxide, potassium fluoride peroxyhydrate, perborates, persulfates, perphosphates, and percarbonates. These compounds have a broad spectrum of antimicrobial activity against bacteria (including Mycobacterium tuberculosis), viruses, fungi, and spores of bacilli.
 The primary exposure targets exposure for oxygen-containing disinfectants are proteins and lipids in the cytoplasmic membranes of bacterial cells and the spore membranes of bacterial spores. When a bacterial cell is exposed to hydrogen peroxide at the stage of contact with the cytoplasmic membrane, hydrogen peroxide decomposes into highly reactive hydroxyl radicals, which have a destructive effect on the membranes. Hydroxyl radicals are powerful oxidizing agents, have a short existence and interact with lipids, proteins, and nucleic acids. Lipid oxidation, mainly unsaturated fatty acids, leads to increased membrane permeability. During the membrane protein oxidation consisting of amino acids with disulfide bonds, the latter are converted into SH-radicals, forming cross-links at amino groups and resulting in protein-lipid complexes. The proteins are oxidized and denatured, leading to cell death. Hydroxyl radicals and other intermediate decomposition products of hydrogen peroxide, such as hydronium cation (Н3О+) and perhydroxylanion (НО2-), have damaging effects.
 This article analyzes scientific papers on the mechanism of action of oxygen-active disinfectants on vegetative cells and bacterial spores.

Characterization of a lytic Escherichia coli phage CE1 and its potential use in therapy against avian pathogenic Escherichia coli infections.

The high incidence of Avian pathogenic Escherichia coli (APEC) in poultry has resulted in significant economic losses. It has become necessary to find alternatives to antibiotics due to the alarming rise in antibiotic resistance. Phage therapy has shown promising results in numerous studies. In the current study, a lytic phage vB_EcoM_CE1 (short for CE1) against Escherichia coli (E. coli) was isolated from broiler feces, showing a relatively wide host range and lysing 56.9% (33/58) of high pathogenic strains of APEC. According to morphological observations and phylogenetic analysis, phage CE1 belongs to the Tequatrovirus genus, Straboviridae family, containing an icosahedral capsid (80 ~ 100 nm in diameter) and a retractable tail (120 nm in length). This phage was stable below 60°C for 1 h over the pH range of 4 to 10. Whole-genome sequencing revealed that phage CE1 contained a linear double-stranded DNA genome spanning 167,955 bp with a GC content of 35.4%. A total of 271 ORFs and 8 tRNAs were identified. There was no evidence of virulence genes, drug-resistance genes, or lysogeny genes in the genome. The in vitro test showed high bactericidal activity of phage CE1 against E. coli at a wide range of MOIs, and good air and water disinfectant properties. Phage CE1 showed perfect protection against broilers challenged with APEC strain in vivo. This study provides some basic information for further research into treating colibacillosis, or killing E. coli in breeding environments.

Oxygen recovery from ozone generators by adsorption processes

As a triatomic allotrope of oxygen, ozone has many industrial and consumer applications because of its high oxidation potential and disinfectant properties. Most of the ozone is currently produced by corona discharge reactors using high-purity oxygen as the feed gas, where the conversion to ozone is typically 6−15 wt%. Given the high operating costs associated with the unreacted oxygen, it is essential to recover the oxygen for recycling to the ozone generator. This paper aims for the first time to design, simulate and assess cyclic adsorption processes for recovering oxygen from a mixture of ozone and oxygen (O3:O2 = 10:90 wt%) produced by a commercial ozone generator. A 2-bed, 2-step cycle was first investigated in which ozone is selectively adsorbed at high pressure and then desorbed by dry air used as a sweep gas. However, it was found that the O2 purity in the recycle stream was too low because of the nitrogen build up from air. Thus, two additional cycles, namely a 3-bed, 3-step cycle incorporating an oxygen purge step and a 3-bed, 4-step cycle incorporating a vacuum blowdown step, were evaluated with the purpose of removing nitrogen from the bed after the desorption step. Both adsorption cycles achieved a satisfactory O2 purity of 98+% in the recycle stream with a sacrifice of O2 recovery and an increase in energy consumption, respectively. As a result, the adsorption processes devised in this study could serve to significantly reduce the oxygen consumption in industrial ozone generators.

Superior photocatalytic performance and photo disinfection of bacteria of solvothermally synthesized mesoporous La-doped CeO2 under simulated visible light irradiation for wastewater treatment

A simple, cost-effective, and facile solvothermal approach has been adopted to synthesize mesoporous CeO2 nanostructures with varying La-doping (2, 4, and 6 mol%) concentrations. Photocatalytic and antibacterial performances are investigated against the inactivation of Escherichia coli and Bacillus licheniformis bacteria cells. Structural and microstructural characterizations of La-doped CeO2 nanostructures are performed by analyzing X-ray diffraction (XRD) data employing the Rietveld refinement method, scanning electron (SEM) and transmission electron microscopy (TEM) images, Brunauer–Emmett–Teller (BET), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) spectra. Among three doped samples, the 4 mol% La-doped CeO2 (LCe4) has exhibited high oxygen and Ce3+ concentrations, high microstrain, small crystallite size, and lowest band gap energy, as are revealed by the analysis of XPS, UV–VIS absorption spectra, photoluminescence (PL) spectra, and Rietveld refinement result. The LCe4 sample with the highest number of oxygen vacancies and high surface area shows superior photocatalytic activity (∼95% Rhodamin B (RhB) degradation in 130 min, ∼70% Methylene Blue (MB) degradation within 30 min, and ∼95% phenol degradation in 180 min under solar radiation). It shows a striking photo-disinfection effect and enhanced antibacterial activity (almost identical to a pure drug) against gram-positive and gram-negative bacteria under visible light irradiation. This novel disinfection and catalytic property of the LCe4 sample is attributed to the mesoporous structure of materials and surface activity, which lowers the electron-hole recombination rate and transports more photogenerated electrons and holes. The nanostructured mesoporous LCe4 material has been used as an effective visible light-activated photocatalyst and photo disinfection for treating wastewater containing organic dyes and gram-negative and gram-positive bacteria.

A Review of the Efficacy of Ultraviolet C Irradiation for Decontamination of Pathogenic and Spoilage Microorganisms in Fruit Juices.

Ultraviolet C (UV-C, 200-280 nm) light has germicidal properties that inactivate a wide range of pathogenic and spoilage microorganisms. UV-C has been extensively studied as an alternative to thermal decontamination of fruit juices. Recent studies suggest that the efficacy of UV-C irradiation in reducing microorganisms in fruit juices is greatly dependent on the characteristics of the target microorganisms, juice matrices, and parameters of the UV-C treatment procedure, such as equipment and processing. Based on evidence from recent studies, this review describes how the characteristics of target microorganisms (e.g., type of microorganism/strain, acid adaptation, physiological states, single/composite inoculum, spore, etc.) and fruit juice matrices (e.g., UV absorbance, UV transmittance, turbidity, soluble solid content, pH, color, etc.) affect the efficacy of UV-C. We also discuss the influences on UV-C treatment efficacy of parameters, including UV-C light source, reactor conditions (e.g., continuous/batch, size, thickness, volume, diameter, outer case, configuration/arrangement), pumping/flow system conditions (e.g., sample flow rate and pattern, sample residence time, number of cycles), homogenization conditions (e.g., continuous flow/recirculation, stirring, mixing), and cleaning capability of the reactor. The collective facts indicate the immense potential of UV-C irradiation in the fruit juice industry. Existing drawbacks need to be addressed in future studies before the technique is applicable at the industrial scale.

Preparation of barium ferrate from mill scale and degradation study of aqueous Eriochrome black – T

This present study involves the utilization of mill scale, an iron rich steel industry waste, to synthesize barium ferrate. Ferrate with iron in +(VI) oxidation state is a green chemical with promising oxidation, disinfection and coagulation properties. The X-Ray diffraction(XRD) analysis of mill scale indicates the presence of iron in three forms hematite, magnetite and wustite. Mill scale was dissolved in concentrated HCl. The metallic composition of dissolved mill scale was determined by Inductively Couple Plasma Mass Spectroscopy(ICP-MS). Barium ferrate was synthesized using the dissolved mill scale by the wet oxidation method. The resulting crude ferrate was washed with different organic solvents to remove the impurities. The product thus obtained was analyzed by chromite method and characterized by Fourier Transform Infrared Spectroscopy(FTIR). Degradation of aqueous Eriochrome Black – T(EBT) with barium ferrate was studied at different pH, time and concentration. The degradation of the dye was monitored by UV-Visible spectroscopy and chemical oxygen demand. The degradation products of the aqueous EBT were characterized by Gas Chromatography-Mass Spectroscopy(GC-MS) and Proton Nuclear Magnetic Resonance (1H-NMR). Computational studies were performed to compare the stability of barium ferrate with that of potassium ferrate. The 1H-NMR calculations were performed to compare the degradation products obtained experimentally.

Effect of plasma‐activated water treatment on physicochemical and functional properties of whey protein isolate

SummaryPlasma‐activated water (PAW) is an emerging nonthermal processing method explored for its food disinfection properties. However, the effect of reactive species in PAW on the food composition has not yet been studied. In this study, a simple protein, whey protein isolate (WPI) was used to understand the effect of PAW reactive species on its physicochemical and functional properties. The results showed mild oxidation of WPI evidenced from the decrease in the sulfhydryl group content and increase in the surface hydrophobicity. Increase in the soluble protein content was observed with PAW 45 min treatment. Foam stability of the PAW‐treated samples increased significantly following PAW treatment. However, no linear change in WPI properties was observed with PAW treatment time. Reduction in the thermal stability of samples was observed in 10 and 50 mg mL−1 concentrations with PAW treatment. The SDS‐PAGE analysis revealed that PAW treatment did not form in‐soluble protein aggregation in WPI samples. FTIR spectrum of the treated WPI samples showed that there were no new functional groups formed by the PAW treatment. Increase in β‐sheet, random coil percentage and reduction in α‐helix percentage was observed in 5 mg mL−1 concentration. The results suggest that the reactive oxygen species in the PAW lead to mild oxidation and unfolding of the WPI samples and improved its foam stability.

ОПРЕДЕЛЕНИЕ ДЕЗИНФИЦИРУЮЩИХ СВОЙСТВ СРЕДСТВА «БАКТЕРИДЕЗ ВЕТ» В ЛАБОРАТОРНЫХ УСЛОВИЯХ

Laboratory studies of the agent «Bacteridez Vet» were carried out, during which it was found that it has disinfectant properties. The studies were carried out on reference strains of microorganisms: Escherichia coli (strain 1257), Staphylococcus aureus (strain 209-P), Mycobacterium (strain B-5), Bacillus cereus (strain 96) and test samples made of smooth and rough materials used at veterinary surveillance facilities. Studies have shown that disinfection of artificially infected E. coli strain 1257 and S. aureus strain 209-P test surfaces achieved: smooth (stainless steel, tile) – 0,1%, rough (wood, concrete) – 1% solutions when exposed to the agent 1 hour, the rate of consumption of the agent 0,25–0,5 l/m2 for all types of surfaces. Disinfection of test surfaces made of wood and concrete contaminated with highly resistant and especially resistant microorganisms was achieved by double spraying, exposure of 24 hours for mycobacteria – 4% concentration, for spores of B. cereus strain 96-6%.

Lethal weapon IL: a nano-copper/tetraalkylphosphonium ionic liquid composite material with potent antibacterial activity

Ionic liquid (IL) based composite materials are promising antimicrobial agents, owing to their inherent germicidal properties, as well as their ability to stabilize metal nanoparticles (NPs), which may serve as a secondary antimicrobial reservoir.

Bacteriophages as therapeutic & disinfectant agents to tackle multidrug-resistant Acinetobacter baumannii.

Multidrug-resistant (MDR) Acinetobacter baumannii is a serious threat for human health worldwide. The studies on agents targeting A. baumannii are imperative due to identified A. baumannii co-infections in COVID-19. Bacteriophages are promising antibacterial agents against drug-resistant bacteria. This study intended to isolate bacteriophages against MDR A. baumannii from the water of river Ganga, to be used potentially as therapeutic and disinfectant particles. Acinetobacter phages were isolated from the Ganga water collected from Kanpur and further tested on 50 MDR A. baumannii isolates to determine host range. The phages were morphologically characterized by transmission electron microscopy. The disinfectant property of the isolated phages was tested by spraying of bacteriophage cocktail on MDR A. baumannii contaminated plastic surface, analyzed by colony-forming unit (CFU) and bioluminescence assay (adenosine triphosphate monitoring). A total of seven bacteriophages were isolated against MDR A. baumannii. The bacteriophages lysed three MDR A. baumannii isolates out of 50 tested, showing narrow host range. Electron microscopy revealed hexagonal heads and long tails of bacteriophages, belonging to order Caudovirales. The bacteriophage cocktail reduced the MDR A. baumannii load efficiently on plastic surface, evidenced by reduction in CFUs and bioluminescence. The findings of this study suggest that the isolated bacteriophages are potential lytic agents for MDR A. baumannii clinical isolates, and may be used as potential therapeutic agents as well as disinfectant to combat MDR A. baumannii with due consideration to phage host specificity, with further characterization.

Treating Bilateral Cornual Tubal Block by Ayurvedic Medications: A Case Study

Tubal diseases accounts for 25%–35% of infertility in women. The line of treatment for it is tubal cannulation and microsurgical reconstruction. Moreover, In Vitro Fertilization (IVF) is suggested to patients post tubal microsurgery. These treatments have low success rate but have high costs. Hence, it is important to look for alternative therapies which are safe and cost-effective. From an Ayurvedic perspective, tubal blockage can be considered as Sangha Srotodushti of Artavabeejvaha srotas due to vitiated Tridosha. This is a case report of a female patient with a Bilateral cornual tubal block with a history of infertility. Due to Kapha -Vata dosha, 5ml Kshartail Uttarbasti was planned for 2 days for 3 consecutive menstrual cycles to remove obstruction produced in the tube. Due to Vyavayi (spreading fast throughout the body), Vikasi (distribution throughout the body without routine digestive process), and Sukshma (minute) properties of Kshartail, it spreads quickly into minute pores of the tube. Due to its Ushna (hot), Tikshna (penetrates deep tissue), Chedan (punctures tissue), and Bhedan (break down of particles) properties it scrapes the obstructing substance and removes fibrosed and damaged endometrial lining of the tube & uterus. Due to its Avakashkara (produces space), Srotoshodhak (purification of srotas) Ropan (wound healing), and disinfectant properties, it promotes the rejuvenation of tissue and improves the conductive functions of tubes and its Snigdha (oily), Ushna (hot) properties neutralises vitiated Vata dosha. After removal of the tubal block, the patient gets conceived naturally within 4 months and delivers a healthy baby. The result suggests that Uttarbasti is a highly effective, safe, low-cost Ayurvedic treatment without apparent complications.

1191. Comparison of High Touch Surface Bioburden Associated with the Use of Disinfectants With and Without Continuously Active Disinfection Properties in Ambulatory Care Settings

Abstract Background Microbial contamination of high-touch surfaces (HTS) in health care settings contributes to pathogen transmission. HTS quickly become re-contaminated after disinfection. A quaternary ammonium (QA) and isopropyl alcohol (IPA)-based disinfectant (Sani-24®) with reported continuously active disinfection (CAD) properties for up to 24 hours has been associated with reduced microbial buildup on HTS over time in in vitro studies and inpatient healthcare settings. The performance of this product in ambulatory care settings has not been reported. Methods HTS bioburden associated with use of QA-IPA with CAD (Sani-24®) was compared to that of a QA-IPA disinfectant without CAD (Super Sani-Cloth®) in an urgent care center (UCC) and outpatient clinic (OPC). Surfaces/rooms were assigned 1:1 to the disinfectants. Study team used pre-saturated wipes to disinfect designated HTS (stretcher/exam table, stretcher rail, armrest, doorknob, counter, light switch) at the beginning of each sampling period. In the UCC, unit staff performed subsequent disinfection per routine protocols. In the OPC, unit staff used the study-assigned disinfectant for disinfection between patients. HTS were sampled at 0, 4-6, 8-12, and 24 hours using Eswabs soaked in neutralizing broth. Microbial burden was quantified after 48 hours of incubation. Average CFU/cm² were compared using T-tests and proportion of samples with < 2.5 CFU/cm², a microbiologic standard for environmental surfaces, were compared by chi-square test. Results 66 UCC HTS (33 per disinfectant) and 70 OPC HTS (35 per disinfectant) were included. There were no statistically significant differences in average CFU/cm² on individual HTS (Figure 1) or average CFU/cm² on all HTS combined between the disinfectants. There were also no significant differences in the proportion of surfaces with < 2.5 CFU/cm² (Figure 2) between the disinfectants. Conclusion No differences were observed in the HTS bioburden in ambulatory settings over 24 hours following disinfection using products with and without CAD. These findings differ from those of studies in other settings, perhaps due to frequent disinfection, less extensive recontamination, or Hawthorne effect in these ambulatory settings. Further study in other ambulatory care settings is warranted. Disclosures Harjot K. Singh, MD, clinical care options: Advisor/Consultant|MJSciences/HCP Live: Advisor/Consultant|NYC Health and Hospitals: Advisor/Consultant Lars Westblade, PhD, Accelerate Diagnostics, Inc.: Grant/Research Support|BioFire Diagnostics, LLC: Grant/Research Support|Hardy Diagnostics: Grant/Research Support|Roche Molecular Systems, Inc.: Advisor/Consultant|Roche Molecular Systems, Inc.: Grant/Research Support|Shionogi, Inc.: Advisor/Consultant|Talis Biomedical: Advisor/Consultant.

Antibacterial smart hydrogels: New hope for infectious wound management.

Millions of people die annually due to uncured wound infections. Healthcare systems incur high costs to treat wound infections. Tt is predicted to become more challenging due to the rise of multidrug-resistant conditions. During the last decades, smart antibacterial hydrogels could attract attention as a promising solution, especially for skin wound infections. These antibacterial hydrogels are termed 'smart' due to their response to specific physical and chemical environmental stimuli. To deliver different drugs to particular sites in a controlled manner, various types of crosslinking strategies are used in the manufacturing process. Smart hydrogels are designed to provide antimicrobial agents to the infected sites or are built from polymers with inherent disinfectant properties. This paper aims to critically review recent pre-clinical and clinical advances in using smart hydrogels against skin wound infections and propose the next best thing for future trends. For this purpose, an introduction to skin wound healing and disease is presented and intelligent hydrogels responding to different stimuli are introduced. Finally, the most promising investigations are discussed in their related sections. These studies can pave the way for producing new biomaterials with clinical applications.

Application of Ozone Therapy in Paediatric Dentistry

The therapeutic use of ozone has been suggested for a long time in general dentistry and paediatric dentistry for its antimicrobial, virucidal, disinfectant, and biocompatible properties. Ozone has also anti-inflammatory, analgesic, and immunostimulant properties, and it promotes tissue regeneration. Dental treatment in children is often complex and ozone could support the clinician to enhance the approach and prognosis with young patients, non-cooperant children, or special needs patients. The efficiency of ozone will certainly increase if studies continue to show positive outcomes in a growing number of dental paediatric conditions. This review explores the recent literature of ozone therapy in paediatric dentistry and suggests fields of application for future randomized controlled trials (RCTs).

Comparative Assessment of Pulsed and Continuous LED UV-A Lighting for Disinfection of Contaminated Surfaces

The germicidal efficacy of LED UV-A lighting has scarcely been compared in continuous and pulsed modes for contaminated surfaces. Herein, we compare the disinfection properties of pulsed versus continuous lighting at equal irradiances using a 365 nm LED device that replicates the doses of occupied-space continuous disinfection UV-A products. Representative organisms evaluated in this study included human-infectious enveloped and non-enveloped viruses (lentivirus and adeno-associated virus, respectively), a bacterial endospore (Bacillus atrophaeus), and a resilient gram-positive bacterium (Enterococcus faecalis). Nominal UV-A irradiances were tested at or below the UL standard limit for continuous human exposure (maximum irradiance of 10 W/m2). We observed photoinactivation properties that varied by organism type, with bacteria and enveloped virus being more susceptible to UV-A than non-enveloped virus and spores. Overall, we conclude that continuous-mode UV-A lighting is better suited for occupied-space disinfection than pulsing UV-A at equivalent low irradiances, and we draw comparisons to other studies in the literature.

Evaluation of plasma‐activated water characteristics and its process optimization

AbstractPlasma‐activated water (PAW) is an emerging technology for the disinfection of foods and it is also widely evaluated for its applications in medicine. The long‐lived reactive oxygen species such as hydrogen peroxide and ozone are mainly responsible for the disinfecting properties of Ar/O2 PAW. In this study, PAW characteristics were evaluated with respect to the process conditions and the post‐treatment time to understand the effect of process conditions and the time stability of PAW. PAW was generated using a continuous flow dielectric barrier discharge Ar/O2 atmospheric pressure plasma system at different PAW treatment times. PAW properties were evaluated based on the concentration of hydrogen peroxide, ozone, pH, and the disinfection of Escherichia coli. From the time stability analysis, it was found that the hydrogen peroxide was more stable than ozone in PAW when stored at room temperature for 2 days. The E. coli inactivation was mainly attributed to the H2O2 and ozone concentration than pH. The optimum process condition was found as 104 ml/min water flow rate, 20‐min treatment time and 4 slm gas flow rate for maximum reactive species concentration in PAW.Practical ApplicationsThere is a need for non‐chemical disinfection method of fresh fruits and vegetables, as the present chemical‐based disinfection methods are inefficient in controlling food‐borne outbreaks and the residual toxicity of these chemicals. Plasma‐activated water (PAW) is an emerging technology, which has the potential in disinfecting microorganisms. The aim of the work was to analyze the disinfection properties and the time stability of PAW. It is evident from the results that PAW is effective in disinfecting Escherichia coli and its reactive species degrade with time. This will facilitate the application of PAW as a disinfectant for fresh fruits and vegetables without any residual toxicity to the food and the environment. Further, from the optimization studies, understanding of the influence of process parameters on the PAW characteristics was derived which will be helpful to scale‐up of this technology.