Air Sterilization Research Articles

Impact Assessment of Saline Aerosols on Exercise Capacity of Athletes

The treatment in natural salt mines (speleotherapy) was known since a very long time ago; the miners and other persons involved in these activities might have known about the great effects of the microclimate within salt mines upon human health, long before they were described in a book published by a Polish doctor in 1843. The effectiveness of speleotherapy is associated with the unique cave microclimate; the sodium chloride aerosols represent the main curative factor. The saline aerosols are formed off the salt walls by convective diffusion.[1] Halotherapy is the natural therapy method which boroughs the main curative factor for speleotherapy, meaning the saline aerosol particles dispersed in the salt mine microclimate.[2]The salt room microclimate should have a constant humidity (a relative air humidity of 40-60%) and a temperature of 18-24¼ Celsius, as these parameters create favourable conditions for patients and they are a stable environment for aerosols.[3-4] The precinct should also ensure a stable environment, bacteria- and allergen-free; studies have shown that the microbial contamination during a halotherapy session is of 130-200 saprophyte microorganisms to 1m3 of air (the WHO standards regarding air sterility are of > 300 microorganisms/1m3 air). Thus, a 10-20minutes break after each session is necessary to purify the air within the chamber.[1]

공기 조화를 위한 자외선 C 살균기의 개발 및 평가

Nowadays, with improvement of economical income and life qualities, life pattern changes have been brought such as increasing of avocational activities. Consequently, following those life trends, utilization of car is getting increased. Thus, the perceptions of car have been changed from the only means of transport in the past to a 2nd residental space. that is why the car`s endo environmental factors are getting so important. Air conditioner regulating air ventilization in vehicle`s indoor automatically sets the right temperature based on the differences of indoor and outdoor`s temperature with development of advanced functions to provide better environmental qualities in vehicle. However, even those advanced techniques for functional development are got so diverse though, the essential technique for preventing the growth of bateria and mold inside of the air conditioner are not even severals. Especially, evaporator one of the vehicle air conditioning equipments generates cooled air by vaporizing refrigerant in liquid state with the water as the adduct for this reactions. It has structural difficulties for water vaporation then cause the growth of germs. That`s why this reseach was focused on the way of eliminating germs in the vehicle air conditioner efficiently. Direct air sterilizer by using UVC(Ultraviolet C) is manufactured and that performances are evaluated.

Ion energy and angular distributions onto polymer surfaces delivered by dielectric barrier discharge filaments in air: II. Particles

Atmospheric pressure streamers intersecting particles are of interest in the context of plasma aided combustion, where the particle may be a fuel aerosol droplet, or in sterilization of air, where the particle may be a bacterium. The ion energy and angular distributions (IEADs) incident on the particles, small curved dielectric surfaces, then in part determine the propensity for activating chemical reactions or, in the case of bacteria, the plasma's sterilization capability. In this paper, we discuss results from a computational investigation of IEADs on small particles (45 µm radius) produced by atmospheric pressure discharge. Streamers intersecting a particle momentarily generate a large sheath potential as the streamer passes by as the particle charges towards the plasma floating potential. During that time, ions of energies up to 3–10 eV can strike the particle. The permittivity of the particle and the streamer polarity in part determine the character of the IEAD.

Occupational Exposure of Dentists to Extremely‐low‐frequency Magnetic Field

To compare occupational exposure to extremely-low-frequency magnetic field (ELF-MF) between dentists practicing in dental clinics and those employed in hospitals. Thirty-two dentists who worked at clinics (n=15) and 33 dentists employed at hospital dental departments (n=7) voluntarily provided their informed consent to participate in this measurement study. The study dentists were requested to wear an ELF-MF dosimeter for some 3 h at work to determine their personal exposure. Spot measurements taken at a number of locations in each dental office were used to indicate the work environment exposure level. Additionally, ELF-MF emitted from common dental equipment was also measured. All measurements were performed with EMDEX Lite meters. The average environmental exposure to ELF-MF is higher in clinic dental offices than in hospital dental departments (0.55 vs. 0.15 µT, p=0.008). Personal dosimetry showed that on average, clinic dentists spent 35.71 and 19.39% of their time at exposures above 0.3 and 0.4 µT at work, respectively. The corresponding figures for hospital dentists were 19.61 and 13.92%. Additionally, ELF-MF was greater than 0.4 µT at 30 cm from all selected equipment, but the ELF-MF generally diminished as the distance from dental equipment increased. Uultraviolet air sterilization system produced 3 times as much ELF-MF as other dental equipment. This study suggests the possibility of over-exposure of dentists to power frequency ELF-MF. Additionally, certain dental equipment may produce ELF-MF levels greater than 0.4 µT in areas where dentists usually work when treating patients.

Inactivation of bacteria and fungus aerosols using microwave irradiation

This study investigated the survivals of both lab-generated and environmental bioaerosols when exposed to the microwave irradiation (2450 MHz) for ∼2 min at different output powers (700, 385 and 119 W). Control and exposed bioaerosols were collected by a BioSampler or a mixed cellulose ester (MCE) filter, and the air samples were further cultured. As a comparison, liquid-borne exposure for one species was also conducted. Environmental scanning electron microscope (ESEM) and transmission electron microscope (TEM) were used to study the membrane surface morphologies and intracellular components of the microwave-treated and untreated microbes. The survival rates of airborne Bacillus subtilis var niger spores were shown to be about 35%, 44% and 35% when exposed to the microwave irradiation for 1.5 min with high, medium and low power applied, respectively ( p-value=0.37). In contrast, the airborne Pseudomonas fluorescens were shown to have lower survival rates of 5.8%, 12.2% and 21% ( p-value=0.0045). Similar patterns but higher survival rates at respective powers were observed for airborne Aspergillus versicolor exposure ( p-value<.0001). For environmental bacterial and fungal bioaerosols, 30–40% of them were shown to survive the high power microwave irradiation for 1.7 min. Outdoor bioaerosols were shown to have stronger survival than the indoor bioaerosols when exposed to the microwave irradiation. ESEM and TEM images showed visible damages to the microwave-irradiated microbes. The results obtained here can be used to develop microwave-based air sterilization technologies especially targeted for biological aerosols.

Deep-Ultraviolet Light-Emitting Diodes

Compact solid-state deep-ultraviolet (DUV) light-emitting diodes (LEDs) go far beyond replacing conventional DUV sources such as mercury lamps. DUV LEDs enable new applications for air, water, and surface sterilization and decontamination, bioagent detection and identification, UV curing, and biomedical and analytical instrumentation. We review materials growth, device physics, design, fabrication, and performance of DUV LEDs with wavelength ranging from 210 to 365 nm, describe prototype systems for water purification and sterilization, and discuss other emerging applications and systems using DUV LEDs.

Thermal effects on bacterial bioaerosols in continuous air flow

Exposure to bacterial bioaerosols can have adverse effects on health, such as infectious diseases, acute toxic effects, and allergies. The search for ways of preventing and curing the harmful effects of bacterial bioaerosols has created a strong demand for the study and development of an efficient method of controlling bioaerosols. We investigated the thermal effects on bacterial bioaerosols of Escherichia coli and Bacillus subtilis by using a thermal electric heating system in continuous air flow. The bacterial bioaerosols were exposed to a surrounding temperature that ranged from 20 °C to 700 °C for about 0.3 s. Both E. coli and B. subtilis vegetative cells were rendered more than 99.9% inactive at 160 °C and 350 °C of wall temperature of the quartz tube, respectively. Although the data on bacterial injury showed that the bacteria tended to sustain greater damage as the surrounding temperature increased, Gram-negative E. coli was highly sensitive to structural injury but Gram-positive B. subtilis was slightly more sensitive to metabolic injury. In addition, the inactivation of E. coli endotoxins was found to range from 9.2% (at 200 °C) to 82.0% (at 700 °C). However, the particle size distribution and morphology of both bacterial bioaerosols were maintained, despite exposure to a surrounding temperature of 700 °C. Our results show that thermal heating in a continuous air flow can be used with short exposure time to control bacterial bioaerosols by rendering the bacteria and endotoxins to a large extent inactive. This result could also be useful for developing more effective thermal treatment strategies for use in air purification or sterilization systems to control bioaerosols.

TiO2-based building materials: Above and beyond traditional applications

In the 1910s, TiO2 began to be used in building materials as pigments and opacifier due to its excellent optical property. Since the photocatalytic property of TiO2 was observed in 1972, its application field was expanded to air cleaning and sterilization. Thereafter, people added TiO2 into building materials to develop novel and facile building materials. These materials were widely used for air cleaning, sterilization, self-cleaning, anti-fogging, decoration, and building cooling. The combination of building and other functions can serve simultaneously. Although TiO2-based building materials have bright prospects, some aspects such as improving the stability and enhancing photoactive performance of the materials are of importance for future research.

Evaluation of Modeling and Measurement Techniques of Ultraviolet Germicidal Irradiation Effectiveness — Towards the Design of Immune Buildings

While concerns about occupants' health, comfort, energy consumption, and environment are becoming a main design consideration for ventilation systems there are also threats to public safety and security that cannot be overlooked and need to be taken into consideration. A sudden release of chemical and biological agents can pose a safety and security threat to public buildings and can cause injuries and loss of life. Recently air-cleaner technology has been introduced for air sterilization and purification in industrial buildings and hospitals due to its long life, functionality, and sustainability. However this technology has not been applied to the nonindustrial built environment in general, and the possibility of a sudden release of chemical or biological agents in particular has not been addressed. This paper presents a detailed review of previous studies on the measurement of ultraviolet germicidal irradiation effectiveness for decontamination, particularly as related to rooms and mechanical systems (ducting) in buildings. It also discusses the methods used to model the space, as well as the measurements and methods used to measure its performance followed by a comparison of the results and discussion of the possible causes of variance in reported data.

Protrusio of a Ceramic Femoral Head Through the Acetabular Metallic Shell, Extensive Metallosis and ‘Bubble Sign’

A 24-year-old patient with a history of juvenile rheumatoid arthritis underwent a primary cementless left total hip arthroplasty (THA). The original THA consisted of an Optifix 54 cup with a 3-mm thick polyethylene liner, an Optifix size 4 stem (Smith & Nephew Richards, Memphis, Tennessee) and a Biolox aluminum 32-mm femoral head. Fourteen years later, radiographs demonstrated extensive wear of the polyethylene liner resulting in direct articulation and abrasion wear of the ceramic femoral head on the cup and a bubble sign. This article presents a case of a catastrophic failure of a ceramic/polyethylene bearing with destruction of the polyethylene liner and the metallic shell and protrusio of the nonfractured ceramic head through the metallic shell. To our knowledge this is the first description of extensive metallosis and subsequent radiograph bubble sign not presenting as a result of wear of a metal-on-metal articulation. At the time of revision surgery-Hydrocel TNT Monoblock 58 cup (Zimmer, Warsaw, Indiana), Wagner 265/14 stem (Zimmer), and a Co/Cr 28-mm head-copious metallic debris was seen both macroscopically and histologically, with the ceramic head protruding behind the metallic shell. Multiple factors may have been responsible for this failure including a thin polyethylene shell, a suboptimal locking mechanism, gamma in air sterilization for polyethylene, multiple screw-holes that reduce the contact surface between shell and polyethylene, the rough surface on the inside of the shell and non-articular wear at the metal polyethylene interface within the acetabular component and the high demands of this active young patient.

METHOD TO EVALUATE GERMICIDAL EFFICIENCY OF UR-UVGI SYSTEM

UVGI (Ultraviolet Germicidal Irradiation) system is recently considered for the sterilization of indoor air and practically applied to the buildings where need hygienic control mainly in America and Europe. In this study, the factors influencing the germicidal effect such as UV intensity and exposure time were reviewed and the several methods to evaluate the germicidal efficacy of UR (Upper Room)-UVGI system were introduced. The methods mainly use CFD simulation to calculate UV dose, considering the distribution of UV intensity of UR-UVGI system and the air flow induced by air handling system in a room. The methods were applied to a typical 4-patient ward model. Results showed that the positions of UR-UVGI system and supply or exhaust openings are important for UV dose. For example, spatial average UV dose decrease when UR-UVGI system is installed near the exhaust openings. Similar results were shown in the cases that the contaminants assumed to be exhausted from the mouth of patient. In the cases assuming infectious microbe flow in through supply openings or breathing of occupant, the germicidal efficacy of UR-UVGI could be evaluated with the methods.

Application of nano-sized TiO2 photocatalysis to air purification and sterilization

To develop and evaluate the efficiency of air purification and sterilization instrument based on nano-sized TiO(2) photocatalytic technique. The nano-sized TiO(2) photocatalytic air purification and sterilization instrument was designed and a sample had been prepared. The sterilization efficiencies for E.coli and Klebsiella by the nano-sized TiO(2) photocatalytic instrument and ultraviolet (UV) were measured in closed labs. The on-site efficiency of the instrument was evaluated, too. The nano-sized TiO(2) photocatalytic air purification and sterilization instrument was composed of five units: rough filter, nano-sized TiO(2) photocatalytic unit, activated carbon fiber filter, negative ion generator, and programmed control unit. The E.coli killing rates by the nano-sized TiO(2) photocatalytic instrument were 76.0%, 81.8%, 77.5%, and 80.7% at 30, 60, 90, and 120 minutes, respectively. There was no significant difference between the E.coli killing rates of the instrument and UV (P > 0.05), except the 120 minutes timepoint. The Klebsiella killing rates by the instrument were 78.4%, 79.5%, 67.3%, and 58.5% at 30, 60, 90, and 120 minutes, respectively. The Klebsiella killing efficiencies of the instrument at 30 and 60 minutes were better than that of UV (P < 0.01). There was no significant difference between the Klebsiella killing efficiencies of the instrument and UV (P > 0.05). The air sterilization efficiency of the nano-sized TiO(2) photocatalytic instrument should be equivalent or better as compared with the UV. This instrument might be used for the air purification and sterilization of the public locations.

Radiographic Assessment of the Thickness Lost from Polyethylene Tibial Inserts That Had Been Sterilized Differently

Archived serial radiographs of knee replacements provide indirect evidence of the clinical performance of ultra-high molecular weight polyethylene tibial bearings. Our purpose was to determine the loss of thickness in polyethylene tibial inserts that were of the same design but had been sterilized differently. Four hundred and sixteen knees with an Anatomic Modular Knee primary total knee replacement had five to eighteen years of follow-up and a posterior cruciate ligament-retaining polyethylene tibial insert that had been sterilized with either gamma radiation in air (from 1987 to 1993) or gamma radiation in an inert gas (from 1993 to 1995), or by means of a nonirradiation gas-plasma method (from 1995 to 2001). Readings were taken from 1975 weight-bearing anteroposterior radiographs of the knee on which the top surface of the metal tibial tray had nearly projected as a line. In each tibiofemoral compartment, loss of polyethylene thickness was calculated as the standard thickness of the insert minus the measured magnification-corrected thickness. For each sterilization method, thickness loss was plotted versus the corresponding follow-up time, and a mixed linear regression model was used to quantify the change in thickness over time. Multiple linear regression analysis was used to determine whether loss of thickness was associated with implant factors, patient variables, and early postoperative limb alignment. According to the mixed model regression coefficients, loss of medial compartment thickness was greatest for inserts that had been sterilized with gamma radiation in air (0.15 mm/yr), least for those sterilized with gamma radiation in an inert gas (0.02 mm/yr), and of an intermediate magnitude for those sterilized with a nonirradiation method (0.06 mm/year); loss of lateral compartment thickness ranged from 0.03 to 0.06 mm/yr. Notably, no insert irradiated in an inert gas showed a loss of thickness of >1 mm, and no nonirradiated insert showed a loss of >2 mm. Loss of medial compartment thickness in inserts sterilized with radiation in air increased significantly with a greater polyethylene shelf age, lesser patient age, and more varus alignment of the limb in the early postoperative period (p < 0.01). In this total knee design, tibial polyethylene performance improved markedly after discontinuation of the gamma radiation in air sterilization technique. Future concerns are that bearings sterilized with radiation in an inert gas may oxidize in vivo and develop fatigue wear because of free radicals generated during sterilization with radiation and that nonirradiated bearings may undergo greater losses in thickness from routine burnishing since they lack the cross-linking that accompanies sterilization with radiation.

All-Solid-State Power Modulator for Pulsed Corona Plasma Reactors

Atmospheric pressure pulsed corona plasma (PCP) reactors of wire-plate design offer novel solutions to environmental issues and to a number of industrial processes. Emerging applications include indoor air sterilization and odor removal in air conditioning systems, chemical synthesis in non-thermal plasmas, and plasma reforming of gaseous fuels. We previously reported on experimental investigations of a laboratory size, wire-plate plasma reactor for pulsed corona treatment of gas flows. Operation with gas flow, at pulse repetition frequencies of between 10 pps and 200 pps, has been achieved at pulse voltage amplitudes of between 10 and >30 kV, at pulse durations of around 0.3 mus (FWHM). High efficiencies of up to 70 g/kWh have been reported using an all-solid-state pulse generator. In this work, we report on the development of all-solid-state power modulators for use with nonlinear loads like pulse corona plasmas. The pulse generators are based on a fast thyristor switch discharging pulse capacitors, a pulse step-up transformer, and one or two stages of magnetic pulse compression. At pulse repetition rates of up to 200 pps, amplitudes of > 30 kV into a resistive-capacitive load (1 kOmega200 pF) have been achieved, at risetimes of about 80 ns and a pulse width of 0.3 mus. The pulse generator is insensitive to load variations, in particular to sparking in the reactor. An advanced generator version uses two magnetic pulse compression stages resulting in even shorter rise times. The modulator and its performance concerning experimental results will be described in detail when driving a pulsed corona reactor.

Industrial applications of atmospheric non-thermal plasma in environmental remediation

Atmospheric non-thermal plasma (NTP) has been recognized as an important tool for the abatement of pollutants and for promoting various chemical reactions in gas or in liquid. Indoor air cleaners have been mass-produced and proved to be effective for the removal of odour and allergen. NTP has various potential applications in environmental remediation, such as the removal of volatile organic pollutants, simultaneous removal of NOx and soot in diesel exhaust and sterilization of air and water. To improve the efficiency of plasma chemical processes, a combination of NTP and catalysts/absorbents is effective. Synergetic effects have been recognized; however, its mechanism remains subject to further investigations. The generation of non-thermal discharge plasma and several industrial applications are presented in this paper.

Performance Evaluation of Air Sterlizer

Sterilized air has an important role in aseptic pouch packaging machine. The main use of sterilized air is in maintaining sterile condition in the filling and a slight positive pressure in relation to the environment, and in removing excess H2O2from the packaging material surfaces. In present study, an air sterilizer was designed and its performance was evaluated. The test was carried out with natural microflora. The bacterial count at velocity of40; m/s varied from 0 to 42; at 30 mls air velocity, bacterial count varied from 0 to 35 while at 20 mis, it was found to vary from 0 to 20 cfu/m3 Bacterial counts were found to be zero above 100 °C at all velocity. The hot air, free from any bacterial load, was used in aseptic pouch packaging machine for different purposes.

Design and optimization of electrostatic fluid accelerators

Electrostatic air propulsion is a promising technology with such potential applications as energy-efficient ventilation, air sterilization, cooling of electronics, and dehumidification. The challenges of existing designs include the need to increase air speed, backpressure, energy efficiency, and heat exchange capability. The ultimate goal of this direction of research is to create multi-channel energy efficient ionic pumps. In the described project, a single cell analysis is conducted in this study as a building block of future designs. This paper presents the numerical simulation and experimental results of electrostatic fluid accelerators. This study was conducted for the purpose of optimizing device characteristics through the control of the electric field distribution. Simulations were performed for multiple collector electrode voltage distributions. A method to quantify the change in pump performance between different voltage distributions is presented. The influence of space charge on pump performance is also discussed. A significant improvement of air velocity generated by optimized electrostatic fluid accelerators has been achieved using the proposed approach.

Observation of Air Sterilization Effect of New Type Chinese Drugs Preparation Xiangliucao

目的 观察中药空气杀菌消毒剂草留香对诊室空气消毒的效果.方法观察在有人活动的情况下草留香对空气的消毒效果,及在无人状态下与常规紫外线空气消毒法进行比较.结果 草留香对空气消毒达到消毒要求,且优于传统紫外线消毒法.结论草留香是一种理想空气消毒剂,在人员不能离开诊室时亦可进行空气消毒,值得临床推广应用。

Sterilization of instruments in solar ovens.

The sterilization of instruments in rural health clinics in less developed countries is an increasing problem as chemical methods can no longer be recommended and fuel wood is becoming increasingly scarce. It seems obvious, therefore, to utilize solar energy for sterilization purposes. A solar oven was designed and manufactured using local materials and simple tools. It was tested by physical, chemical and microbiological methods and, after successful testing, installed in a rural clinic. The oven was able to generate temperatures above 180 degrees C. On days with direct sunlight the oven fulfilled the international recommendations for hot air sterilization. The chemical indicators, Browne's tubes type 3 and 5, also changed colour. It was difficult to reach the right value for the sterilization effect during months with a low sun position. A moveable oven, or two ovens, must be installed to solve this problem. The solar oven has proven to be a realistic method for the sterilization of instruments. The solar oven is easy to make and use. It saves fuel and can be used in most tropical areas.

Current industrial practice in solid state fermentations for secondary metabolite production: the Biocon India experience

Solid substrate fermentation at Biocon was originally envisaged for the production of enzymes, used in the food processing industry. The original process developed at Biocon was a hygienically designed automated tray culture process. Plants using this process still continue to run effectively at Biocon, and produce a variety of products meeting and exceeding FCC/JECFA specifications for food products. Biocon recently designed, developed and patented a new bioreactor, the PlaFractor™ (pronounced play-fractor) for carrying out fermentations that use solid matrices—a term covering both nutritive support matrices as well as non-nutritive matrices impregnated with medium. Using the PlaFractor™ process it is now possible to extend the use of solid matrix fermentation for the production of enzymes, biocontrol agents and pharmaceutical products, that require elaborate containment—under precisely defined conditions. The production takes place in computer controlled bioreactors, using complex fermentation control algorithms. All the operations of solid matrix fermentation, i.e. sterilization, cooling, inoculation, fermentation and process control, product recovery and post-fermentation sterilization, are all done in one single equipment, which was not hitherto possible. All the advantages of traditional solid state fermentation, over submerged fermentation, like low energy consumption, low water requirement, high mass transfer coefficient, no foaming, and high product concentrations are retained. In addition, techniques that are important to submerged fermentation, like fed-batch fermentation, process parameter profiling, air and media sterilization, operation under aseptic environments, and ease of handling, can now be easily applied to solid state fermentation, because of the way this bioreactor is designed. A production plant, built around this bioreactor has already been operating for more than a year.