High Concentration Of Gas Research Articles

Corrosion Characteristics of Polymer-Modified Oil Well Cement-Based Composite Materials in Geological Environment Containing Carbon Dioxide.

Oil well cement is easily damaged by carbon dioxide (CO2) corrosion, and the corrosion of oil well cement is affected by many factors in complex environments. The anti-corrosion performance of oil well cement can be improved by polymer materials. In order to explore the influence of different corrosion factors on the corrosion depth of polymer-modified oil well cement, the influence of different corrosion factors on corrosion depth was studied based on the Box-Behnken experimental design. The interaction of different influencing factors and the influence of multiple corrosion depths were analyzed based on the response surface method, and a response surface model was obtained for each factor and corrosion depth. The results indicate that within the scope of the study, the corrosion depth of polymer-modified oil well cement was most affected by time. The effects of temperature and the pressure of CO2 decreased sequentially. The response surface model had good significance, with a determination coefficient of 0.9907. The corrosion depth was most affected by the interaction between corrosion time and the pressure of CO2, while the corrosion depth was less affected by the interaction between corrosion temperature and corrosion time. Improving the CO2 intrusion resistance of cement slurry in an environment with a high concentration of CO2 gas can effectively ensure the long-term structural integrity of cement.

A ppb-level NO2 gas sensor with ultra-high concentration shock resistance characteristics based on In2O3-In2(MoO4)3

Metal oxides are widely used because of their simple structure, low price, and excellent gas-sensitive properties. But now, the metal oxide sensor faces two challenges. One is that when the detection limit of the sensor is low, it will be affected by a high concentration of gas and fail in practical applications. Second, the metal oxide sensor is susceptible to temperature changes, resulting in inaccurate measurement results. To address the above problems, the performance of metal oxides is enhanced through doping. Indium oxide doped with various levels of indium molybdate was prepared using a two-step hydrothermal method resulting in a composite material with an n-n heterostructure. The interaction formed by the n-n heterostructure enhances the redox reaction between NO2 gas and the sensor, and the unique nano cluster structure provides more active sites for the sensor, significantly improving the gas performance of the sensor towards NO2. Sensors based on In2(MoO4)3 with a doping ratio of 4 % (the sample IM3) showed excellent gas sensitivity. The lower and upper detection limits of the sensor are 200 ppb (response is 1.46) and 150 ppm (response is 515.94), respectively. And the sensor has good resistance to ultra-high concentration (10000 ppm) nitrogen dioxide (NO2) impact. In the range of 130–170°C, the temperature has a small and linear effect on the sensor response, which is very beneficial for temperature correction of gas sensors. The sensor prepared by In2(MoO4)3 doped In2O3 composite material has a good potential for application in engineering practice.

High-voltage AlGaN/GaN heterojunction lateral photoconductive semiconductor switch based on semi-insulating 4H-SiC substrate

A novel high-power AlGaN/GaN heterojunction lateral photoconductive semiconductor switch (PCSS) based on the SiC substrate is proposed, which achieves high dark-state resistance characteristics by groove etching. Under the action of biased electric field and incident laser, a high concentration of two-dimensional electron gas is formed at the heterojunction interface. The photo-generated free carriers transport along the heterojunction interface, which improves the utilization efficiency of photo-generated carriers. Moreover, the simulation of the current density distribution of the PCSS provides theoretical support for this phenomenon. Compared with the conventional GaN PCSS, the power capacity and conduction characteristics are further improved. The test results show that the output current of the device increases significantly after the introduction of the AlGaN/GaN heterojunction. At the biased voltage of ∼34 kV, the maximum output current of the AlGaN/GaN PCSS reaches 205 A.

High efficiency electricity and gas cogeneration through direct carbon solid oxide fuel cell with cotton stalk biochar

For the first time, biochar derived from a renewable resource, cotton stalk, is used as the feedstock of direct carbon solid oxides fuel cells (DC-SOFCs) for electricity and gas cogeneration. It turns out that the cotton stalk biochar has plenty of naturally grown K and Ca, which are active catalysts for the reverse Boudouard reaction in DC-SOFCs. This natural advantage of the cotton stalk biochar enables an extremely high power density of an anode-supported DC-SOFC at 850 °C, 0.9 W cm−2, which is the highest among those of the reported DC-SOFCs. Meanwhile, high concentration of CO gas, which is an important feedstock for chemical industry, is obtained from the DC-SOFCs. The energy conversion efficiency of the electricity-gas cogeneration of DC-SOFCs reaches over 70%. A novel method, using compressed char, is proposed and carried out for continuous supply of cotton stalk char to a DC-SOFC. The present work has demonstrated the feasibility and advantages of cogenerating electricity and gas through DC-SOFCs with biochar derived from cotton stalk as the feedstock.

A multi-objective optimal collaborative gas flow regulation method for non-stationary ventilation network based on improved NSGA-Ⅲ algorithm

After the shockwave of a coal and gas outburst disappears, the influx of a high concentration of gas causes ventilation network disorder. This will further lead to the occurrence of secondary disasters, resulting in serious human and economic losses. This study focuses on solving the cooperative regulation problem of non-stationary ventilation networks (NSVNs) after a disaster. The NSVN solution model is dynamically combined with the ventilation network regulation method to simulate the results of post-disaster cooperative regulation. The Pareto optimal solution for decision variables is obtained with the goals of reducing the affected area, preventing the reversal of branch airflow, and rapidly discharging the high concentration of gas. In this regard, an NSGA-III algorithm based on segmented hybrid coding with conditional distribution sampling is designed to solve the problem of the population crossover operation under the dynamic change of the decision variables. In addition, according to the applicability of the decision variables in the regulation of NSVNs, the sampling distribution function that meets the practical application requirements is selected. Moreover, conditional distribution sampling is carried out for chromosome generation via real number coding, the aim of which is to improve the search efficiency and optimization effect. Via the hierarchical logical relationship between the decision variables, conversion is carried out to generate population individuals of different dimensions to realize the dynamic inputs of the NSVN solution model and calculate the corresponding target values. Finally, the feasibility of the proposed model and solution method is verified by studying and analyzing the case of an airflow disaster in a coal mine in Jiulishan, China. This study provides theoretical support for the cooperative regulation of NSVNs, as well as guidance for the post-disaster emergency rescue work in possible coal and gas herniation accidents.

Numerical Study on Leakage Dispersion Pattern and Hazardous Area of Ammonia Storage Tanks

Ammonia can be extremely dangerous if it leaks during storage and use. Therefore, in this article, the ammonia leakage diffusion law is investigated and the hazardous area is analyzed by establishing numerical model and simulating the diffusion process of concentration, flow rate, and temperature of ammonia storage tanks at different leakage locations, wind speeds, and leakage amounts. In the results, it is shown that when the leakage port is located at the top of the tank, and ammonia in high concentrations is more deflected and closer to the surface with the increase of wind speeds, the high concentration of ammonia gas gradually takes a vertical shape with the increase of leakage volume. When the leakage location is at the bottom of the storage tank, the leeward side area is the hazardous area with the increase of wind speed. The area and height of the cloud of highly concentrated ammonia increase with the increase of leakage volume. When the leak is located on the side of the tank and the wind direction opposite side, with the increase of wind speed both sides of the tank are in the hazardous area. High concentrations of ammonia will spread backward across the tank with the increase of leakage volume.

Determine the hazards of radioactive elements and radon gas manufacturing processes in an Egyptian fertilizer factory

This study investigated the levels of radioactivity in soil surrounding a phosphate fertilizer factory in Egypt, aiming to assess potential risks to the population exposed to radiation. Concentrations of 238U, 226Ra, 232Th, and 40K were measured in soil samples collected from two subsites: one near the factory (subsite 1) and another further away (subsite 2). Two different systems were used for measuring radioactivity, a high-purity gamma ray spectroscopy system with an HPGe detector for gamma-emitting isotopes and a CR-39 solid nuclear track detector for alpha-emitting radon gas. Subsite 1, located close to the factory, displayed significantly elevated levels of 226Ra compared to global background levels (514 and 456 Bq/kg vs. 35 Bq/kg). Additionally, the concentrations of 238U (241.06 Bq/kg vs. global average 35 Bq/kg), 232Th (16.15 Bq/kg vs. global average 30 Bq/kg), and 40K (146.36 Bq/kg vs. global average 400 Bq/kg) were all above global averages. Furthermore, a high concentration of radon gas (337.06 μSv/y) was measured at subsite 1. The strong positive correlation observed between 226Ra and 238U (0.96256) provides further evidence of potentially elevated radioactivity levels near the factory. In contrast, subsite 2, situated farther from the factory, exhibited natural radioactive background levels within international limits. Quantitative analysis revealed that gamma ray absorbed doses for 226Ra and 232Th exceeded global averages in some samples. Specifically, 226Ra doses ranged from 7.8 to 46.26 ppm (exceeding the 20 ppm global average in some cases), and 232Th doses ranged from 1.98 to 9.14 ppm (exceeding the 10 ppm global average in some cases). The concentration of 40K, however, remained within the global range (0.07%–0.69 %). The observed imbalances in the ratios of Th/U (0.17–0.24 Bq/kg and 0.73–0.24 ppm) and U/Ra (0.81–0.73 Bq/kg and 0.73–0.17 ppm), both of which are significantly lower than their respective global averages of 4 and 2.4, point towards the presence of fertilizer-derived contamination. This conclusion is further supported by the high phosphate concentrations detected in the samples. Overall, this study suggests that radioactive contamination near the phosphate fertilizer factory significantly exceeds global background levels and international limits in some cases. This raises concerns about potential risks posed to surrounding agricultural land and crops.

Fixation of air nitrogen to ammonia and nitrate using cathodic plasma and anodic plasma in the air plasma electrolysis method

AbstractThe fixation of nitrogen (N2) from the air into ammonia (NH3) and nitrate (NO3−) is usually conducted using the Haber–Bosch process, which requires the raw material of hydrocarbons for hydrogen (H2), which has a large amount of energy but produces high CO2 emissions. An environmentally friendly and energy‐saving alternative is the air plasma electrolysis method, which can be used to synthesize NH3 and NO3− under ambient conditions. In this study, this method was used to inject air into the plasma zone in a K2SO4 electrolyte solution to produce N2 fixation compounds. The results showed that the use of cathodic plasma promoted the formation of NH3 but suppressed NO3− production. The optimal air injection rate was achieved at 0.6 L.min−1 and an electrical power of 452 W, with a total fixed N2 of 51.66 mmol. The highest formation of NO3− in cathodic plasma was obtained in 35 min, with a value of 29.92 mmol, and 2.57 mmol NH3 was achieved at 60 min. The high concentration of H2 gas, which is a by‐product of this process, can contribute to increasing the use of Haber–Bosch green technology in the production of NH3.

Research on gas hazard prevention and control of a high-gas fully mechanized mining face based on ventilation system optimization.

The gas accumulation in the return corner of a high-gas fully mechanized mining face can easily cause the gas volume fraction to exceed the safety limit, threatening the safety of coal mines. In this study, the unit method was used to analyze the gas sources and emissions based on the actual case. The airflow and gas distribution characteristics of the two-inlet-one-outlet (TIOO) ventilation system and the one-inlet-two-outlet (OITO) ventilation system were studied using CFD numerical simulation. The results show that under the TIOO ventilation system, the "U"-type air leakage in the goaf leads deep gas into the return corner, which causes the gas volume fraction in the return corner to rise to 0.4-2.0%. After the mining face is optimized into the OITO ventilation system, the "J"-type air leakage of the goaf suppresses the high concentration of gas in the deep position of the goaf. Combined with the gas extraction measures, the gas volume fraction in the return corner, exhaust roadway's outlet, and retaining roadway's outlet is controlled at 0.28%, 0.34%, and 0.23%. This study will provide new ideas for solving the problem of gas accumulation in the return corner of a high-gas fully mechanized mining face.

Monitoring Uji Kualitas Udara Dan Tingkat Kebisingan Di SMAN 1 Semarapura Kabupaten Klungkung

Air pollution occurs due to the amount of pollutants that exceed the maximum limit affecting ambient air quality. Pollutant gases are produced predominantly from uncontrolled community activities, one of which is using transportation facilities. Air quality test research has been carried out at SMAN 1 Semarapura, Klungkung Regency, in the context of observing a river safety development project. Based on the analysis, the results obtained from air quality measurements for the parameter sulfur dioxide (SO2) 37.5 μg/m3; nitrogen dioxide (NO2) 6.5 μg/m3; oxidant (O3) 6.8 μg/m3; carbon monoxide (CO) 1150 μg/m3; lead (Pb) 0.002 μg/m3; total dust (TSP) 72.3 μg/m3; hydrogen sulfide (H2S) 0.017 ppm and a noise level of 43.8 dBA. These parameter values are still below the ambient air quality standards stipulated in Peraturan Gubernur Bali No. 16 Tahun 2016. Meanwhile, the ammonia (NH3) parameter is worth 9.5 mg/m3, which exceeds the ambient air quality standard. The high concentration of ammonia gas in the air can disrupt ecosystems and the health of the human body. Ammonia gas accumulating in the body can interfere with the respiratory system and irritate the respiratory tract. Therefore it is necessary to periodically monitor air quality to overcome the impact of air pollution.

Based on laser energy absorption ratio differential algorithm methane concentration detection system

To reduce the interference of other gases and improve the detection accuracy in CH4 concentration detection, a CH4 concentration detection system is proposed, and a ratio differential algorithm is designed. The difference value of the absorbed light intensity between chamber 1 and chamber 2 used to suppress the calculation of CH4 concentration by other component gases. The high concentration of CH4 gas in chamber 3 used to obtain the accurate position of the characteristic absorption peak, and it is applied as a boundary condition for data extraction in chamber 1. Two sets of gases chamber differential calculations were used, one set was used to calculate the differential value of laser energy at the characteristic position of CH4 absorption, and the other set was used to calculate the differential value of laser energy for the other gases. Then, calculate the proportion coefficients of the two sets of difference values to obtain the CH4 concentration inversion function using this structure. The interfering gases include C2H6, SO2 and CO2. A total of 1,000 sets for sample data were collected for the mixed gas, with 400 sets as the sample data and the rest as the test samples. The results show that the accuracy of CH4 concentration inversion by this algorithm is about 3 times that of traditional algorithm. The algorithm modeling time is approximately 1/4 of that of traditional methods. It has certain advantages in detecting CH4 concentration in environments with interfering gases.

Interfacial heat transfer with non-condensable gas in ASTEC V2.2: Application to severe accidents study during PWR cold shutdown states

In a diphasic flow, the presence of non-condensable gas has an important impact on interfacial heat transfer, especially at low global pressure. In severe accidents studies, such flow can be commonly encountered. For example, in pressurised water reactors, high concentration of non-condensable gas can be found in the reactor coolant system in case of late core reflooding with a high oxidation rate (high hydrogen concentration) or in case of accidents happening during the cold shutdown of the reactor, when the reactor coolant system has been partly drained (high air concentration). Such flows with non-condensable gas are challenging to compute for severe accident system codes. A new model is implemented in ASTEC v2.2 to improve the interfacial heat transfer calculation in presence of non-condensable gas. The model gives a more accurate estimation of the heat transfer by assuming that it is mainly driven by vapour diffusion in the gas phase. The new model is applied to study cold shutdown states for 1300 MWe pressurized water reactors. A complete calculation of the cooling, depressurisation and draining of the reactor can be successfully performed. In order to show ASTEC new capabilities, a first accident scenario with loss of the residual heat removal system is also presented.

Association analysis of accident factors in petrochemical storage tank farms

In order to identify and clarify the association between the factors leading to accidents in a petrochemical tank area, this study analyzes investigation reports of 212 petrochemical tank farm accidents and combines this with the “association rule” mining and science related to complex networks. The main risk factors are determined and a risk factor data set is constructed; 75 association rules are extracted from the factor data set based on the Apriori algorithm. Then the obtained association rules are used to construct an accident factors network of the petrochemical storage tank area, and the topology characteristics of the network are further analyzed to reveal the importance of factors. Factors with large node degree, betweenness, and clustering coefficients are obtained, such as “violation of operating regulations”, “high concentration of flammable gas in the air”, “lack of experience and professional skills”, etc. These factors play an important role in the formation and development of accidents. The results also show that the accident cause network of the petrochemical storage tank area has a small average shortest path length and a large cluster coefficient, indicating a relatively close connection between the accident factors. The contributions of this study is not only extracting the hidden relationships among contributory factors to tank farm accidents using association analysis, but also revealing which factors are more important for the tank farm safety through the complex network.

Formaldehyde Gas Sensing Characteristics of ZnO-TiO2 Gas Sensors

Since the increase in the emission of various Volatiles Organic Compounds, gas and formaldehyde gas have had a harmful effect on the human body, and gas sensors that can measure those gases were fabricated in this study. After Pt coating was performed on the alumina substrate, Zn seed layers were fabricated. Nanostructures were formed through sonochemical synthesis by varying the ratio of ZnO and TiO2. Thereafter, the reactivity and recovery properties were compared and evaluated according to the concentrations of formaldehyde and toluene gas. The ZnO(99%)-TiO2(1%) gas sensor showed meaningful selectivity of about 40% or more at a concentration ranging from 5 to 20 ppm (high concentration) of formaldehyde and toluene gas, and showed a low selectivity of about 5% or more for a concentration ranging from 0.1 to 1 ppm (low concentration) of formaldehyde and toluene gas. This sensor can be optimized to have a meaningful selectivity of formaldehyde gas compared to other Volatiles Organic Compounds gases by optimizing the ZnO-TiO2 nanostructure.

Improvement of SiO2 surface morphology during the selective Si3N4 etching in the multi-layered 3D NAND Si3N4/SiO2 stack structures by the generation of CO2 gas through the control of redox reaction

Selective removal of silicon nitride (Si3N4) layers from multilayer Si3N4/silicon dioxide (SiO2) stack structures is essential for fabricating 3-dimensional (3D) NAND flash memory devices. Although phosphoric acid (H3PO4) selectively etches Si3N4 layers to a certain degree, the tip thicknesses of the SiO2 layers increase owing to oxide regrowth, and the SiO2-layered trenches become clogged. In particular, the oxide regrowth phenomenon worsens as it progresses to the bottom of the structure. In this study, carbon dioxide (CO2) gas was generated by adding acidic reducing agents to H3PO4 to suppress the oxide regrowth in the stack structure. CO2 gas creates a turbulent flow in the slits and SiO2/Si3N4/SiO2 trenches, promoting the diffusion of Si3N4 etch byproducts from the cul-de-sac of the SiO2/Si3N4/SiO2 trench structures to the outside of the stack structure. The addition of oxalic acid to H3PO4 generated a high concentration of CO2 gas and selectively etched Si3N4 layers without oxide regrowth in the stack structure. Finally, the selective etching of Si3N4 layers, which is faster and more uniform than that in pure 85 wt.% H3PO4, was performed without oxide regrowth in the entire 128-layer Si3N4/SiO2 multi-stack structure.

Experimental and modelling study of hydrogen ignition in CO2 bath gas

Direct-fired supercritical CO2 power cycles, operating on natural gas or syngas, have been proposed as future energy technologies with 100 % carbon capture at a price competitive with existing fossil fuel technologies. Likewise, blue or green hydrogen may be used for power generation to counter the intermittency of renewable power technologies. In this work, ignition delay times (IDTs) of hydrogen were measured in a high concentration of CO2 bath gas over 1050 – 1300 K and pressures between 20 and 40 bar. Measured datasets were compared with chemical kinetic simulations using AramcoMech 2.0 and the University of Sheffield supercritical CO2 (UoS sCO2 2.0) chemical kinetic mechanisms. The UoS sCO2 2.0 mechanism was recently developed to model IDTs of methane, hydrogen, and syngas in CO2 bath gas. Sensitivity analyses were used to identify important reactions and to illustrate the trends observed among various datasets. The performance of both mechanisms was evaluated quantitatively by comparing the average absolute error between the predicted and experimental IDTs, which showed UoS sCO2 2.0 as the superior mechanism for modelling hydrogen IDTs in CO2 bath gas. The importance of OH time-histories is identified as the most appropriate next step in further validation of the kinetic mechanism.

Effects of High Concentration Nitrogen Gas Stunning of Pigs on the Quality Traits of Meat and Small Intestine.

Simple SummaryTo satisfy consumer demand, it is necessary to ensure the quality of the meat and small intestine of animals. For consideration of animal welfare and to obtain an adequate quality of the meat and small intestine, animals need to be stunned to minimize anxiety, pain, distress, or suffering. Electric stunning and exposure to a high concentration of carbon dioxide (CO2) are common stunning methods in the meat industry. However, both methods have some limitations. Pale color and a higher tendency of ecchymosis is the common feature in electric-stunned pigs’ meat. Exposure to higher concentration of carbon dioxide induces high aversion, irritation of nasal mucosal membranes, and severe respiratory distress causing hyperventilation and breathlessness in pigs. Hypercapnia, hyperglycemia, lactic acidosis, and an increased hematocrit also occur in pigs. To reducing the negative impacts of CO2, inert gases (i.e., Argon and N2) are sometimes mixed with CO2. But, the amount of Argon in the atmosphere is very negligible (0.93%) and Argon has a high cost in the market. To maintain hypercapnic–hypoxia and improve stability, a higher concentration of N2 has sometimes been mixed with CO2 and used in pig stunning. But, no trial has used only high concentration of nitrogen in the stunning of animals, while maintaining a hypoxic condition (less than 2% O2 in atmosphere). Our study involved conducting a trial on electricity, CO2 (80%), and high concentrations of nitrogen (98%) in the stunning of pigs and comparing the meat and small intestine quality traits. Findings show that the meat and small intestine quality of N2 (98%)-stunned pigs was favorable compared to the other treatment groups.The objective of present study was to investigate the feasibility of utilizing only high concentration of nitrogen gas in the stunning of pigs and its effects on the quality traits of the meat and small intestine.To conduct this experiment, three treatment groups were compared: (i) electric stunning (T1), (ii) CO2 (80%) gas stunning (T2), and (iii) N2 (98%) gas stunning (T3). A total of 21 standard pigs (Landrace × Yorkshire × Duroc; LYD) were collected from a commercial pig farm, randomly selecting seven pigs for each group (body weight of 104.5 to 120.6 kg). For stunning, each individual pig was separately kept in a gas chamber, after which each specific gas was used to fulfill the desired level in the pit. To obtain the desired level of concentration for each gas (N2 at 98% and CO2 at 80%), approximately 80 min and 35 min were required, respectively. It was observed that after reaching the desired level of concentration, pigs were stunned within a very short time (for CO2, 90 s and for N2, 120 s). For electric stunning, standard quality electric devices were used. After slaughtering, the meat and small intestine of each animal was collected separately and kept in a cool room where temperature was −2 °C. In the meat and small intestine, L* (Lightness) and b* (Yellowness) were high (p < 0.05) in the T1 and T3 groups. The T2 group showed high a* (Redness) (p < 0.05) values in both the meat and small intestine. A proximate composition of meat showed no significant differences except moisture. The water holding capacity (WHC), cooking loss (CL), and Warner-Bratzler shear force (WBSF) of meat were lowest in the T2 group, but not at a notable difference compared to T3. In the small intestine, L* (Lightness), a* (Redness), b* (Yellowness), and thickness significantly differed (p < 0.05) in each group, but WBSF showed no significance between the T2 and T3 groups. It is concluded that a high concentration of N2 gas (98%) may be considered in the stunning of pigs, and its effect on meat and small intestine is favorable.

A study on the differences in radon exhalation of different lithologies at various depths and the factors influencing its distribution in northern Shaanxi, China

The inhalation of a high concentration of radon gas increases the risk of cancer. Therefore, it is of utmost necessity to pay due attention to the problem of environmental radon pollution. The high radioactivity above the coal slab causes serious radon radiation contamination on the mining grounds in coal mining areas such as the northern part of China and the western part of the United States. At present, there is a lack of research on radon exhalation in different lithologies. In this study, the differences in the radon exhalation of different lithologies at various depths and their controlling factors were studied by NMR and radon measurement. The results highlighted that the radon exhalation rates in different rocks varied from 0.3 to 0.6 Bq/m2·s. The average radon exhalation rate of the soil was 0.7 Bq/m2·s, and the radon exhalation rates of different lithologies followed the pattern red clay > loess > sandstone > mudstone > coal. The radon exhalation rate increased initially, followed by a decrease, and the radon exhalation rate was the highest at the boundary between the soil and rock layers. The radon exhalation rates of different lithologies have a strong correlation with the small pores (<0.1 μm), which govern the changes in the porous structure with depth. The results of this study are important from the perspective evaluation of environmental radon pollution.

Localized Liquid Zones Assisted Highly Crystalline Single-Wall Carbon Nanotube Sheets: Implications for Conducting Shields in Coaxial Cables

The electrical conductivity of carbon nanotube (CNT) macro assemblies can be influenced by their crystallinity. Herein, we present the synthesis of high-quality SWCNT sheets for which an appropriate optimization parametric research of synthesis temperature, precursor flow rate, and H2 flow rate was carried out in this approach. It was found that highly crystalline SWCNT sheet (IG/ID = 180.3) was synthesized by floating catalyst chemical vapor deposition technique at 12 mL/h precursor flow rate and 1000 sccm H2 flow rate. Three distinct Raman laser wavelengths (514, 532, and 785 nm) were used to study the as-synthesized sheet, and the maximum calculated IG/ID ratio was found to be 180.3 (@ λ = 514 nm). Due to high concentration of H2 gas, the number of localized liquid zones or CNT nucleation sites increased which has an impact on both the quality as well as the diameter of CNTs. The I–V characteristics of CNT sheet were studied via four-probe technique, yielding a measured value of electrical conductivity of 9.21 × 106 S/m. Further, the R-T measurement showed the positive temperature coefficient up to the 108 K which indicates the metallicity of as produced CNT sheets. These highly conducting SWCNT sheets are the best solution for a wide range of applications in many fields, including conducting shields in coaxial cables, flexible and nano scale electrical and electronic devices, displays, biosensors, field-effect transistors and gas sensing materials.

Potent Activity of a High Concentration of Chemical Ozone against Antibiotic-Resistant Bacteria.

Background: Health care-associated infections (HAIs) are a significant public health problem worldwide, favoring multidrug-resistant (MDR) microorganisms. The SARS-CoV-2 infection was negatively associated with the increase in antimicrobial resistance, and the ESKAPE group had the most significant impact on HAIs. The study evaluated the bactericidal effect of a high concentration of O3 gas on some reference and ESKAPE bacteria. Material and Methods: Four standard strains and four clinical or environmental MDR strains were exposed to elevated ozone doses at different concentrations and times. Bacterial inactivation (growth and cultivability) was investigated using colony counts and resazurin as metabolic indicators. Scanning electron microscopy (SEM) was performed. Results: The culture exposure to a high level of O3 inhibited the growth of all bacterial strains tested with a statistically significant reduction in colony count compared to the control group. The cell viability of S. aureus (MRSA) (99.6%) and P. aeruginosa (XDR) (29.2%) was reduced considerably, and SEM showed damage to bacteria after O3 treatment Conclusion: The impact of HAIs can be easily dampened by the widespread use of ozone in ICUs. This product usually degrades into molecular oxygen and has a low toxicity compared to other sanitization products. However, high doses of ozone were able to interfere with the growth of all strains studied, evidencing that ozone-based decontamination approaches may represent the future of hospital cleaning methods.