Assessment of the possibility of surgical masks re-use after a sterilization process in the pandemic condition of COVID-19

The aim of this study was to explore the possibility to re-use disposable masks in order to prevent excessive waste generation during the pandemic period. The COVID-19 pandemic has caused rapidly increasing waste production resulting from the necessity of common usage of disposable personal protective equipment. This research covers the evaluation of the structure of surgical masks subjected to a threefold steam, gas or plasma sterilization process in order to verify the possibility of their re-use. The results of the study showed that gas sterilization even after three cycles did not cause significant changes in mask structure or air permeability. Hydrogen peroxide plasma sterilization caused significant changes in the structure of layer A after the third cycle of sterilization; nonetheless, it did not influence the air permeability of the mask. A significant reduction in the cover ratio of layers composing surgical masks causes an increase of air permeability in the case of steam sterilization, leading to a reduction of the mechanical ability to prevent the penetration of microorganisms. The reduction in cover ratio limits the filtration efficiency. Surgical masks subjected to threefold gas sterilization can be recommended for re-use. This allows one to use the mask thrice, ensuring safety for users and limiting the mask-waste production to one-third of the volume compared with when the mask is used once. The volume of mask-waste can be reduced with the application of the sterilization process for used masks during the pandemic period. Currently, it is not possible to sterilize all one-use masks, but implementation of this method in hospitals and medical centers is a step in the pro-environmental direction.

Susceptibility of Staphylococcus epidermidis to Argon Cold Plasma Jet by Oxygen Admixture

Cold atmospheric pressure sterilization is one of the nominated and efficient techniques to prevent the spread of diseases. Reactive species such as O and OH and other radicals play a major role in the mechanism of plasma sterilization. Therefore, in this work, oxygen was mixed with different parentage from (0.2 to1.2%) to argon to enhance the generation of the reactive species and increase the argon atmospheric pressure plasma sterilization efficacy. The emission spectra from the jet increase the radicle line intensities by increasing the percentage admixture of O2 with the argon gas to reach a maximum power at 0.8; then, it gradually decreases with a higher O2 percentage. The OH band intensity decreases with increasing the admixture of O2. The jet with different O2 percentages was tested against Gram-positive S. epidermidis, which is the causal agent of nosocomial infections. The maximum reduction in colony-forming units (CFU) was observed at 0.2% O2. No bacterial growth was observed at the later concentration applied for 8 min and the same case was detected at 0.4% O2 applied to 16 min.

Design of a Switching Flyback Transformer as High Voltage and Frequency Power Supply for Raw Milk Cold Plasma Sterilization

Plasma is one of the four fundamentals states of matter other than solid, liquid and gas. In terms of temperature, plasma can be classified into Hot Plasma occurs in thermal equilibrium, Thermal Plasma occurs in non-thermal equilibrium, Cold Plasma occurs in non-thermal equilibrium Cold plasma is an ultra-fast method of sterilization that operates under ambient temperatures (ideal for thermolabile products) at a low running cost and is environment-friendly. Therefore, technology is needed to solve the problem through the innovation of a milk sterilization machine with the principle of non-thermal plasma sterilization by utilizing plasma technology to reduce microbial contamination. The output frequency and voltage are determined through software simulation using voltmeter, oscilloscope, and counter timer. After 220VAC supplies a voltage step down and rectifier circuit to produce a 12VDC output voltage to supply the Switching circuit voltage and the Flyback Transformer driver. Rated voltage and frequency reach 20kV 15kHz.The positive wire from the Flyback Transformer is connected to the acrylic box filled with water (positive electrode) and the ground wire is connected to another acrylic sheet (ground electrode. The milk medium to be sterilized can be placed on the positive electrode or between the ground and positive electrodes. Non-thermal plasma has an effective ability to decontaminate bacteria. This is because plasma is composed of a mixture of ionized particles, reactive radical molecules, and also ultraviolet Schematic circuit design has been successfully simulated. Acrylic sterilization media designs can be used to generate plasma. The mechanism of bacterial sterilization in milk is by the activity of inhibiting bacterial biofilms which can lead to bacterial DNA damage through reactive species in the non-thermal plasma used. Milk quality testing is carried out based on comparison of supporting literature with milk quality requirements according to SNI 3950: 2014.

Synergistic Effects of Bacteriocin from Lactobacillus panis C-M2 Combined with Dielectric Barrier Discharged Non-Thermal Plasma (DBD-NTP) on Morganella sp. in Aquatic Foods

In this paper, Lactocin C-M2(C-M2) was used together with a new non-thermal technology, non-thermal plasma sterilization (NTPS), to inactive the putrefactive bacteria Morganella sp. wf-1 isolated from aquatic foods. The mechanism underlining the action mode of C-M2 and NTPS was investigated, revealing that the bacteriocin and NTPS had synergistic effects on the disinfection of Morganella sp. wf-1. Compared with the bacteria cells treated by only C-M2 or NTPS, the plasmolysis of cells treated by C-M2 and NTPS was to a larger extent. Moreover, the cell permeability and the contents of UV-absorbing compounds and K+ released from the intra-cells was significantly higher for the C-M2 + NTPS treated cells than the others (p < 0.05), and conversely was the SFA/UFA ratio (p < 0.05). The results on DNA damage showed that, 8-hydroxy-2′-deoxyguanosine(8-OHdG) content in C-M2 + NTPS treated cells was approximately 7 -fold and 2.5-fold greater than those in the C-M2- and NTPS-treated cells, respectively, indicating furthermore the eventual rupture of Morganella sp. wf-1 cells. The results showed the potential of the application of the bacteriocin and NTPS in the food industry.