Ying Liu, Kai Li, Zijun He, Liancheng Zhang, Xuming Zhang
Objective: Non-thermal plasma is a promising method for producing clean fuels. This work provides a deeper understanding of the impact of O2/n-C5H12 ratio on the partial oxidation of n-pentane from both physical and chemical perspectives. Moreover, this work offers insight into improving fuel combustion efficiency and technical support for the preparation of clean fuels. Methods: An experimental system based on dielectric barrier discharge plasma was established. The discharge characteristics and product generation status of n-pentane partial oxidation were measured by changing the concentration of oxygen and n-pentane to evaluate different O2/n-C5H12 ratios. Results: Research on discharge characteristics showed that the O2/n-C5H12 ratio did not affect the discharge mode, and typical Lissajous shapes were present at different ratios. Changing the O2/n-C5H12 ratio affected the oxygen concentration, average electron energy or electron density, and background temperature. As the O2/n-C5H12 ratio increased, the conversion of the n-pentane partial oxidation reaction increased. However, changing the O2/n-C5H12 ratio did not affect the type of generated products. The oxygenates exhibited a volcano curve, and an O2/n-C5H12 ratio of 1.00 achieved the highest selectivity of 35.1%. As the O2/n-C5H12 ratio continued to increase, the selectivity of oxygenates decreased and the selectivity of CO2 increased. This was potentially due to a shift from partial oxidation toward complete oxidation, which led to the generation of secondary pollutants. Thus, higher O2/n-C5H12 ratios were not conducive to clean fuel production and environmental friendliness. Conclusion: In the partial oxidation of n-pentane, the highest clean fuel production rate was achieved when the O2/n-C5H12 ratio was 1.00. When this ratio exceeded 1.00, the reaction shifted toward complete oxidation, producing secondary pollutants. This study provides ideas for improving fuel combustion efficiency and technical support for the preparation of clean fuels.
{"title":"Effect of O2/n-C5H12 Ratio on Oxygenates Production from Plasma N-pentane Partial Oxidation","authors":"Ying Liu, Kai Li, Zijun He, Liancheng Zhang, Xuming Zhang","doi":"10.53964/mltp.2024001","DOIUrl":"https://doi.org/10.53964/mltp.2024001","url":null,"abstract":"Objective: Non-thermal plasma is a promising method for producing clean fuels. This work provides a deeper understanding of the impact of O2/n-C5H12 ratio on the partial oxidation of n-pentane from both physical and chemical perspectives. Moreover, this work offers insight into improving fuel combustion efficiency and technical support for the preparation of clean fuels. Methods: An experimental system based on dielectric barrier discharge plasma was established. The discharge characteristics and product generation status of n-pentane partial oxidation were measured by changing the concentration of oxygen and n-pentane to evaluate different O2/n-C5H12 ratios. Results: Research on discharge characteristics showed that the O2/n-C5H12 ratio did not affect the discharge mode, and typical Lissajous shapes were present at different ratios. Changing the O2/n-C5H12 ratio affected the oxygen concentration, average electron energy or electron density, and background temperature. As the O2/n-C5H12 ratio increased, the conversion of the n-pentane partial oxidation reaction increased. However, changing the O2/n-C5H12 ratio did not affect the type of generated products. The oxygenates exhibited a volcano curve, and an O2/n-C5H12 ratio of 1.00 achieved the highest selectivity of 35.1%. As the O2/n-C5H12 ratio continued to increase, the selectivity of oxygenates decreased and the selectivity of CO2 increased. This was potentially due to a shift from partial oxidation toward complete oxidation, which led to the generation of secondary pollutants. Thus, higher O2/n-C5H12 ratios were not conducive to clean fuel production and environmental friendliness. Conclusion: In the partial oxidation of n-pentane, the highest clean fuel production rate was achieved when the O2/n-C5H12 ratio was 1.00. When this ratio exceeded 1.00, the reaction shifted toward complete oxidation, producing secondary pollutants. This study provides ideas for improving fuel combustion efficiency and technical support for the preparation of clean fuels.","PeriodicalId":169878,"journal":{"name":"Modern Low Temperature Plasma","volume":" 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140993039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xixi Jing, Shengduo Xu, Hao Zhang, Han Xu, Dingxin Liu
Objective: In recent years, the anticancer effect induced by cold atmospheric plasma (CAP) has received much attention and has become a rapidly growing research topic. The purpose of this article is to study the anticancer effect of CAP combined with drugs to seek more efficient anticancer therapy. Methods: The plasma source used in this study was surface air discharge plasma, and the anticancer drug was thymidine (TMD). Breast cancer cells (MCF-7) and cervical cancer cells (HeLa) were treated in vitro to evaluated the anticancer effect of the combination of the two therapy. The anticancer efficiency was assessed by detecting cell viability and cell apoptosis rate. And the combined anticancer mechanism was further analyzed by measuring intracellular reactive oxygen species (ROS) levels. Results: The results of cell viability and cell apoptosis showed that the combined anticancer effect of plasma and TMD was significantly better than TMD treatment alone, but not as good as plasma treatment alone. Intracellular ROS levels were increased by plasma treatment of MCF-7 and HeLa cells, and ROS played an important role in plasma-induced apoptosis of cancer cells. In addition, TMD didn’t induce intracellular ROS production, but only interfered with DNA replication and normal division of cancer cells and could increase the stress of cell division, thus inducing apoptosis of cancer cells. Conclusion: TMD may interfere with the targets of plasma action and affect the anticancer effects of plasma, which indicated that not all anticancer drugs can achieve synergistic effect with plasma, and some drugs even interfere with plasma action.
目的：近年来，冷大气等离子体（CAP）诱导的抗癌效应备受关注，已成为一个迅速发展的研究课题。本文旨在研究 CAP 与药物结合的抗癌效果，以寻求更有效的抗癌疗法。研究方法本研究使用的等离子体源为表面空气放电等离子体，抗癌药物为胸腺嘧啶（TMD）。对乳腺癌细胞（MCF-7）和宫颈癌细胞（HeLa）进行体外处理，以评估两种疗法结合的抗癌效果。抗癌效果通过检测细胞活力和细胞凋亡率来评估。并通过测量细胞内活性氧（ROS）水平进一步分析了联合抗癌机制。结果细胞活力和细胞凋亡结果显示，血浆和 TMD 的联合抗癌效果明显优于 TMD 单独治疗，但不如血浆单独治疗。血浆处理 MCF-7 和 HeLa 细胞后，细胞内 ROS 水平升高，ROS 在血浆诱导癌细胞凋亡中发挥了重要作用。此外，TMD 不会诱导细胞内 ROS 的产生，只会干扰 DNA 复制和癌细胞的正常分裂，并能增加细胞分裂的应激反应，从而诱导癌细胞凋亡。结论TMD可能干扰血浆的作用靶点，影响血浆的抗癌作用，这表明并非所有抗癌药物都能与血浆产生协同作用，有些药物甚至会干扰血浆的作用。
{"title":"Combined Anticancer Effect of Treatment with Cold Atmospheric Plasma and Thymidine","authors":"Xixi Jing, Shengduo Xu, Hao Zhang, Han Xu, Dingxin Liu","doi":"10.53964/mltp.2023010","DOIUrl":"https://doi.org/10.53964/mltp.2023010","url":null,"abstract":"Objective: In recent years, the anticancer effect induced by cold atmospheric plasma (CAP) has received much attention and has become a rapidly growing research topic. The purpose of this article is to study the anticancer effect of CAP combined with drugs to seek more efficient anticancer therapy. Methods: The plasma source used in this study was surface air discharge plasma, and the anticancer drug was thymidine (TMD). Breast cancer cells (MCF-7) and cervical cancer cells (HeLa) were treated in vitro to evaluated the anticancer effect of the combination of the two therapy. The anticancer efficiency was assessed by detecting cell viability and cell apoptosis rate. And the combined anticancer mechanism was further analyzed by measuring intracellular reactive oxygen species (ROS) levels. Results: The results of cell viability and cell apoptosis showed that the combined anticancer effect of plasma and TMD was significantly better than TMD treatment alone, but not as good as plasma treatment alone. Intracellular ROS levels were increased by plasma treatment of MCF-7 and HeLa cells, and ROS played an important role in plasma-induced apoptosis of cancer cells. In addition, TMD didn’t induce intracellular ROS production, but only interfered with DNA replication and normal division of cancer cells and could increase the stress of cell division, thus inducing apoptosis of cancer cells. Conclusion: TMD may interfere with the targets of plasma action and affect the anticancer effects of plasma, which indicated that not all anticancer drugs can achieve synergistic effect with plasma, and some drugs even interfere with plasma action.","PeriodicalId":169878,"journal":{"name":"Modern Low Temperature Plasma","volume":" 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139139667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Objective: Plasma catalysis is regarded as a promising technology in mitigating atmospheric CO2, but there is still a gap between industrial demand and current efficiency. This paper aimed to investigate the synergistic effect between vibrational states and catalyst surfaces in plasma catalysis, and to offer a theoretical guide on how to maximize the effectiveness of the synergistic effect in a more energy-efficient way. Methods: A novel 1D dielectric barrier discharge plasma catalysis model has been developed. The Arrhenius equations were used to solve the surface catalytic chemistry. The influence of CO2 vibrational excitation on surface reaction rates were expressed in the framework of the theoretical-informational approach. Results: The simulation suggested that a lower electron temperature fosters vibrational excitation, while a higher electron temperature promotes electronic excitation, therefore, the CO2 conversion rate and energy efficiency were difficult to be improved simultaneously. Furthermore, our model elucidates the pivotal role of catalysts in achieving efficient decomposition of vibrationally excited CO2 (CO2v). However, under conditions of low vibrational density, this synergistic effect fails to yield substantial improvements in catalytic efficiency under low vibrational density conditions. Conclusion: By increasing the pulse voltage, using narrow pulses with rapid rise times, implementing rapid cooling techniques and enlarging the surface catalytic area, the concentrations of CO2v can be augmented. Consequently, the dissociation rate via the V-V process and surface processes can both be enhanced, thereby potentially enabling simultaneous improvements in the CO2 conversion rate and energy efficiency.
{"title":"The CO2 Conversion in a DBD Plasma: A 1D Synergistic Catalysis Model","authors":"He Cheng, Xiaoting Lei, Xinpei Lu","doi":"10.53964/mltp.2023008","DOIUrl":"https://doi.org/10.53964/mltp.2023008","url":null,"abstract":"Objective: Plasma catalysis is regarded as a promising technology in mitigating atmospheric CO2, but there is still a gap between industrial demand and current efficiency. This paper aimed to investigate the synergistic effect between vibrational states and catalyst surfaces in plasma catalysis, and to offer a theoretical guide on how to maximize the effectiveness of the synergistic effect in a more energy-efficient way. Methods: A novel 1D dielectric barrier discharge plasma catalysis model has been developed. The Arrhenius equations were used to solve the surface catalytic chemistry. The influence of CO2 vibrational excitation on surface reaction rates were expressed in the framework of the theoretical-informational approach. Results: The simulation suggested that a lower electron temperature fosters vibrational excitation, while a higher electron temperature promotes electronic excitation, therefore, the CO2 conversion rate and energy efficiency were difficult to be improved simultaneously. Furthermore, our model elucidates the pivotal role of catalysts in achieving efficient decomposition of vibrationally excited CO2 (CO2v). However, under conditions of low vibrational density, this synergistic effect fails to yield substantial improvements in catalytic efficiency under low vibrational density conditions. Conclusion: By increasing the pulse voltage, using narrow pulses with rapid rise times, implementing rapid cooling techniques and enlarging the surface catalytic area, the concentrations of CO2v can be augmented. Consequently, the dissociation rate via the V-V process and surface processes can both be enhanced, thereby potentially enabling simultaneous improvements in the CO2 conversion rate and energy efficiency.","PeriodicalId":169878,"journal":{"name":"Modern Low Temperature Plasma","volume":" 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139141519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yue Hua, Lingyu Zhao, Qian Zhao, G. Xia, Xiuling Zhang, L. Di
Objective: Controllable synthesis of high-performance palladium catalysts toward 4-nitrophenol (4-NP) reduction still remains a significant challenge. This work aims to exploit a facile dielectric barrier discharge (DBD) plasma treatment method to synthesize the graphene-supported palladium catalysts (Pd/G-P), and to as certain the effect of plasma discharge voltage and discharge time on the structure-performance relationship of Pd/G-P, then provides insight into the synthesis of high-performance Pd/G-P by DBD plasma. Methods: A graphene-supported palladium precursor was prepared by excess impregnation method firstly, and then treated using hydrogen DBD plasma to synthesize Pd/G-P catalysts. The effect of discharge voltage and discharge time on the structure-performance relationship of Pd/G-P were systematically investigated based on the reaction model of 4-NP reduction. Results: The Pd/G-P prepared by DBD plasma at discharge voltage of 13.0kV and discharge time of 4min exhibited the highest performance for 4-NP reduction with a rate constant (k) of as high as 0.88min-1. The discharge diagnosis and sample characterization results showed that Pd/G-P with much higher than Pd/C and O/C atomic ratios, and surface defects density can be obtained at the optimal discharge parameters. These features enabled the formation of small-sized and highly-dispersed palladium nanoparticles, thereby enhancing the catalytic activity. The experimental study of reaction kinetics showed that plasma synthesized Pd/G-P at optimal parameters can adsorb intermediate reactants more effectively and enhance the catalytic performance. Conclusion: In this work, controllable synthesis of high-performance Pd/G-P were synthesized, which provides important reference significance for preparing other catalysts by plasma regulation.
{"title":"Cold Plasma for Preparation of Pd/graphene Catalysts toward 4-nitrophenol Reduction: Insight into Plasma Treatment","authors":"Yue Hua, Lingyu Zhao, Qian Zhao, G. Xia, Xiuling Zhang, L. Di","doi":"10.53964/mltp.2023007","DOIUrl":"https://doi.org/10.53964/mltp.2023007","url":null,"abstract":"Objective: Controllable synthesis of high-performance palladium catalysts toward 4-nitrophenol (4-NP) reduction still remains a significant challenge. This work aims to exploit a facile dielectric barrier discharge (DBD) plasma treatment method to synthesize the graphene-supported palladium catalysts (Pd/G-P), and to as certain the effect of plasma discharge voltage and discharge time on the structure-performance relationship of Pd/G-P, then provides insight into the synthesis of high-performance Pd/G-P by DBD plasma. Methods: A graphene-supported palladium precursor was prepared by excess impregnation method firstly, and then treated using hydrogen DBD plasma to synthesize Pd/G-P catalysts. The effect of discharge voltage and discharge time on the structure-performance relationship of Pd/G-P were systematically investigated based on the reaction model of 4-NP reduction. Results: The Pd/G-P prepared by DBD plasma at discharge voltage of 13.0kV and discharge time of 4min exhibited the highest performance for 4-NP reduction with a rate constant (k) of as high as 0.88min-1. The discharge diagnosis and sample characterization results showed that Pd/G-P with much higher than Pd/C and O/C atomic ratios, and surface defects density can be obtained at the optimal discharge parameters. These features enabled the formation of small-sized and highly-dispersed palladium nanoparticles, thereby enhancing the catalytic activity. The experimental study of reaction kinetics showed that plasma synthesized Pd/G-P at optimal parameters can adsorb intermediate reactants more effectively and enhance the catalytic performance. Conclusion: In this work, controllable synthesis of high-performance Pd/G-P were synthesized, which provides important reference significance for preparing other catalysts by plasma regulation.","PeriodicalId":169878,"journal":{"name":"Modern Low Temperature Plasma","volume":"33 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139247920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Background: Atmospheric pressure plasma as a green preservation technology for fruits and vegetables can effectively reduce the number of microorganisms on the surface of fruits and vegetables to achieve the effect of reducing the decay rate and prolonging the freshness period. In addition, plasma can affect the quality of fruits and vegetables and delay the aging of fruits and vegetables. However, the intrinsic mechanism by which plasma affects the quality of fruits and vegetables is unclear. Objective: The aim of this work is to observe the quality changes of Citrus sinensis Osbecks led by plasma treatment during storage period and to analyze the intrinsic mechanism behind it, for the purpose of providing a theoretical reference or the application of plasma in fruit preservation and quality enhancement. Methods: Postharvest Citrus sinensis Osbecks were treated with dielectric barrier discharge (DBD) for 5min, and then the total soluble solids, titratable acids and solid-acid ratios of fruit pulp during storage before and after treatment were measured using a hand-held digital refractometer, and an acid-base burette. Changes in melatonin, sucrose converting enzyme, and simple sugar content of fruit were measured with an ultraviolet-visible spectrophotometer. Results: It was found that the soluble solids and solid-acid ratio of Citrus sinensis Osbecks by DBD treated were significantly increased during storage, while titratable acid did not change significantly. Melatonin and sucrose converting enzyme measurements revealed that plasma treatment significantly increased melatonin content and sucrose converting enzyme activity in the pulp. Measurements of monosaccharides showed that the glucose and fructose contents of the treated Citrus sinensis Osbeck pulp increased, while the sucrose content decreased. Conclusion: The reactive oxygen and nitrogen species generated with DBD plasma can effectively increase the melatonin content in the pulp of Citrus sinensis Osbecks, thereby improving citrus quality including promoting sugar conversion and enhancing flavor.
{"title":"Plasma Affects Sugar Conversion during Storage of Citrus sinensis Osbeck: Melatonin Is a Key Factor","authors":"Xiangyu Ma, Congfu Ran, Xiongfeng Zhou, Kun Liu","doi":"10.53964/mltp.2023006","DOIUrl":"https://doi.org/10.53964/mltp.2023006","url":null,"abstract":"Background: Atmospheric pressure plasma as a green preservation technology for fruits and vegetables can effectively reduce the number of microorganisms on the surface of fruits and vegetables to achieve the effect of reducing the decay rate and prolonging the freshness period. In addition, plasma can affect the quality of fruits and vegetables and delay the aging of fruits and vegetables. However, the intrinsic mechanism by which plasma affects the quality of fruits and vegetables is unclear. Objective: The aim of this work is to observe the quality changes of Citrus sinensis Osbecks led by plasma treatment during storage period and to analyze the intrinsic mechanism behind it, for the purpose of providing a theoretical reference or the application of plasma in fruit preservation and quality enhancement. Methods: Postharvest Citrus sinensis Osbecks were treated with dielectric barrier discharge (DBD) for 5min, and then the total soluble solids, titratable acids and solid-acid ratios of fruit pulp during storage before and after treatment were measured using a hand-held digital refractometer, and an acid-base burette. Changes in melatonin, sucrose converting enzyme, and simple sugar content of fruit were measured with an ultraviolet-visible spectrophotometer. Results: It was found that the soluble solids and solid-acid ratio of Citrus sinensis Osbecks by DBD treated were significantly increased during storage, while titratable acid did not change significantly. Melatonin and sucrose converting enzyme measurements revealed that plasma treatment significantly increased melatonin content and sucrose converting enzyme activity in the pulp. Measurements of monosaccharides showed that the glucose and fructose contents of the treated Citrus sinensis Osbeck pulp increased, while the sucrose content decreased. Conclusion: The reactive oxygen and nitrogen species generated with DBD plasma can effectively increase the melatonin content in the pulp of Citrus sinensis Osbecks, thereby improving citrus quality including promoting sugar conversion and enhancing flavor.","PeriodicalId":169878,"journal":{"name":"Modern Low Temperature Plasma","volume":"8 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139268502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haiyu Li, Zhenyun Zhou, Dong Liu, Yunqiu Cui, Yuan Sun, Jiaxin Li, Yiming Wang, Zhishang Wang, Zhiguo Zhao, N. Lu
Objective: If a medical device is not properly disinfected, it will pose a potential danger to patients. Spore is an experimental strain to verify the effect of disinfection on medical devices. It has a complex structure and is somewhat resistant to conventional disinfection techniques. Based on the advantages of simple structure and abundant reactive oxygen and nitrogen species (RONS), surface dielectric barrier discharge (SDBD) has been used to deal with inactivate spores, which provided experimental support for the application of sterilization spores in medical devices. Methods: The sterilization efficiency of the plasma was evaluated by calculating the number of viable colonies on Tryptose Soya Agar. RONS including ozone, nitrogen oxides and other reactive species produced in SDBD were measured by ozone analyzer, Fourier infrared spectrometer and chemical probes, respectively. Ultraviolet-visible spectrophotometer was used to determine the concentration of protein and nucleic acid. Results: After 20min of SDBD treatment, the number of inactivated spores could reach more than 4 log at high humidity (>6g/m3), while the spores were hardly inactivated at low humidity (<6g/m3). Ozone production was inhibited with increasing humidity while OH radicals and peroxynitrous acid increased with increasing humidity. The optical density values of protein and nucleic acid released from spores treated with SDBD was detected and a strong correlation was found with the spore inactivation trend. The protein shell and membrane structure of the spores were destroyed by SDBD, and more leakage and destruction of proteins and nucleic acids in the spores were obtained under the high humidity. Conclusion: With the increase of air humidity (from 0.15g/m3 to 70.16g/m3), stable SDBD is obtained showing a typical filamentous discharge pattern. Compared with low humidity, high humidity is more favorable to SDBD inactivation of spores.
{"title":"Effect of Humidity on the Inactivation of Bacillus Subtilis Spore by Non-thermal Atmospheric Air Plasma","authors":"Haiyu Li, Zhenyun Zhou, Dong Liu, Yunqiu Cui, Yuan Sun, Jiaxin Li, Yiming Wang, Zhishang Wang, Zhiguo Zhao, N. Lu","doi":"10.53964/mltp.2023005","DOIUrl":"https://doi.org/10.53964/mltp.2023005","url":null,"abstract":"Objective: If a medical device is not properly disinfected, it will pose a potential danger to patients. Spore is an experimental strain to verify the effect of disinfection on medical devices. It has a complex structure and is somewhat resistant to conventional disinfection techniques. Based on the advantages of simple structure and abundant reactive oxygen and nitrogen species (RONS), surface dielectric barrier discharge (SDBD) has been used to deal with inactivate spores, which provided experimental support for the application of sterilization spores in medical devices. Methods: The sterilization efficiency of the plasma was evaluated by calculating the number of viable colonies on Tryptose Soya Agar. RONS including ozone, nitrogen oxides and other reactive species produced in SDBD were measured by ozone analyzer, Fourier infrared spectrometer and chemical probes, respectively. Ultraviolet-visible spectrophotometer was used to determine the concentration of protein and nucleic acid. Results: After 20min of SDBD treatment, the number of inactivated spores could reach more than 4 log at high humidity (>6g/m3), while the spores were hardly inactivated at low humidity (<6g/m3). Ozone production was inhibited with increasing humidity while OH radicals and peroxynitrous acid increased with increasing humidity. The optical density values of protein and nucleic acid released from spores treated with SDBD was detected and a strong correlation was found with the spore inactivation trend. The protein shell and membrane structure of the spores were destroyed by SDBD, and more leakage and destruction of proteins and nucleic acids in the spores were obtained under the high humidity. Conclusion: With the increase of air humidity (from 0.15g/m3 to 70.16g/m3), stable SDBD is obtained showing a typical filamentous discharge pattern. Compared with low humidity, high humidity is more favorable to SDBD inactivation of spores.","PeriodicalId":169878,"journal":{"name":"Modern Low Temperature Plasma","volume":"636 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121986833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Objective: The purpose of this paper is to find a reasonable composite structure of electromagnetic protection device, especially the distribution characteristics of plasma parameters and operation conditions. Methods: Due to its high collision frequency, the high-pressure discharge plasma can be usedas a filling medium to take the electromagnetic protection effect. The strategies and algorithmsare presented to solve the propagation characteristics of electromagnetic wave (EMW) in plasma with complex dielectric constant. When the real and imaginary part of permittivity are of the same order of magnitude, the imaginary part value will impact on the feature of plasma dielectric constant, also affect the behavior of propagation of EMW. The propagation process of EMW in virtual human brain (VHB) model is investigated by finite difference time domain method. By optimizing the layout of plasma layer and air layer, an effective phase regulator is constructed, and the reflected wave amplitude is greatly reduced. Results: The simulation results show that plasma makes the amplitude of the electromagnetic fields in VHB decrease to different degrees. their maximum average decrease is about 25% and the corresponding reduction of SAR value is more than 40% in the frequency range of 1.8-3.6GHz. Conclusion: The existence of plasma can make the scalp and muscle possess the excellent performance in resisting the incident of EMW, so that the amplitude of the electromagnetic field inside the brain body is small, so as to effectively protect the brain tissue. These research results have good reference value and engineering applicability for the structure design of protection equipment with high frequency of EMW.
{"title":"Effects of High-collision Plasma on Radiation Protection of Human Brain","authors":"Yuhuan Liu, T. Guo, Chaoxiang Guo, Yingqin Zeng, Xiangrui He, Songliu Yuan","doi":"10.53964/mltp.2023004","DOIUrl":"https://doi.org/10.53964/mltp.2023004","url":null,"abstract":"Objective: The purpose of this paper is to find a reasonable composite structure of electromagnetic protection device, especially the distribution characteristics of plasma parameters and operation conditions. Methods: Due to its high collision frequency, the high-pressure discharge plasma can be usedas a filling medium to take the electromagnetic protection effect. The strategies and algorithmsare presented to solve the propagation characteristics of electromagnetic wave (EMW) in plasma with complex dielectric constant. When the real and imaginary part of permittivity are of the same order of magnitude, the imaginary part value will impact on the feature of plasma dielectric constant, also affect the behavior of propagation of EMW. The propagation process of EMW in virtual human brain (VHB) model is investigated by finite difference time domain method. By optimizing the layout of plasma layer and air layer, an effective phase regulator is constructed, and the reflected wave amplitude is greatly reduced. Results: The simulation results show that plasma makes the amplitude of the electromagnetic fields in VHB decrease to different degrees. their maximum average decrease is about 25% and the corresponding reduction of SAR value is more than 40% in the frequency range of 1.8-3.6GHz. Conclusion: The existence of plasma can make the scalp and muscle possess the excellent performance in resisting the incident of EMW, so that the amplitude of the electromagnetic field inside the brain body is small, so as to effectively protect the brain tissue. These research results have good reference value and engineering applicability for the structure design of protection equipment with high frequency of EMW.","PeriodicalId":169878,"journal":{"name":"Modern Low Temperature Plasma","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121062389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chemodynamic therapy is (CDT) a novel emerging cancer treatment based on the Fenton-Fenton like reactions. During the Fenton chemical process, hydrogen peroxide in the presence of iron is converted to hydroxyl radical which is a highly reactive species to induce cell damage. The tumor optimal conditions for the occurrence of the Fenton-Fenton like reaction are: a high concentration of hydrogen peroxide, low pH level, and low Glutathione concentration. The requirement for these conditions limit us to achieving the best results from cancer chemodynamic therapy, thus combination with other treatments may be necessary. Here, using current research and a cell model, firstly we introduce the limitations of chemodynamic therapy in cancer treatment and then propose that cold atmospheric plasma could be a suitable candidate for combination with chemodynamic therapy to overcome these limitations.
{"title":"The Perspective of Chemodynamic Therapy Combination with Plasma in Cancer Treatments","authors":"L. K. Gadallo","doi":"10.53964/mltp.2023003","DOIUrl":"https://doi.org/10.53964/mltp.2023003","url":null,"abstract":"Chemodynamic therapy is (CDT) a novel emerging cancer treatment based on the Fenton-Fenton like reactions. During the Fenton chemical process, hydrogen peroxide in the presence of iron is converted to hydroxyl radical which is a highly reactive species to induce cell damage. The tumor optimal conditions for the occurrence of the Fenton-Fenton like reaction are: a high concentration of hydrogen peroxide, low pH level, and low Glutathione concentration. The requirement for these conditions limit us to achieving the best results from cancer chemodynamic therapy, thus combination with other treatments may be necessary. Here, using current research and a cell model, firstly we introduce the limitations of chemodynamic therapy in cancer treatment and then propose that cold atmospheric plasma could be a suitable candidate for combination with chemodynamic therapy to overcome these limitations.","PeriodicalId":169878,"journal":{"name":"Modern Low Temperature Plasma","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121730059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Baowei Zhou, Yunxiang Luo, He Cheng, Qingnan Xu, Shuqun Wu
Objective: Atmospheric pressure plasma jet is one of the promising plasma sources for biomedical applications. This work provides insight into the plasma dynamics near the substrate surface during the plasma treatment. Methods: Two-dimensional modeling of a helium plasma jet impinging on substrates with different relative permittivity and surface morphology is implemented. Results: When the tip of the plasma jet touches the substrate surface, there is a strong electric field and a high density of surface charge on the surface. The higher the substrate’s relative permittivity, the higher density of electrons and excited states near the surface are obtained, and the smaller area of the plasma on the surface is observed. For the wavy surface of the substrate, a surface ionization wave slowly propagating along the protrusions of the substrate is observed. It propagates along the protrusions (rather than the concaves), resulting in no plasma being generated directly inside the concaves. Detailed analysis shows that because the height and width of the concaves are smaller than the thickness of the plasma sheath, the narrow space of the concaves probably restricts the direct production of plasma inside it. Conclusion: The increase of substrate permittivity is beneficial to the production of electrons and chemical species but limits the radial propagation of the plasma along the surface. To generate the plasma directly inside the narrow concaves for the uneven surface of the substrate, the electron density or the width of the concaves should increase.
{"title":"Numerical Investigation of a Helium Plasma Jet Impinging on Substrates: Effects of Relative Permittivity and Surface Morphology","authors":"Baowei Zhou, Yunxiang Luo, He Cheng, Qingnan Xu, Shuqun Wu","doi":"10.53964/mltp.2023002","DOIUrl":"https://doi.org/10.53964/mltp.2023002","url":null,"abstract":"Objective: Atmospheric pressure plasma jet is one of the promising plasma sources for biomedical applications. This work provides insight into the plasma dynamics near the substrate surface during the plasma treatment. Methods: Two-dimensional modeling of a helium plasma jet impinging on substrates with different relative permittivity and surface morphology is implemented. Results: When the tip of the plasma jet touches the substrate surface, there is a strong electric field and a high density of surface charge on the surface. The higher the substrate’s relative permittivity, the higher density of electrons and excited states near the surface are obtained, and the smaller area of the plasma on the surface is observed. For the wavy surface of the substrate, a surface ionization wave slowly propagating along the protrusions of the substrate is observed. It propagates along the protrusions (rather than the concaves), resulting in no plasma being generated directly inside the concaves. Detailed analysis shows that because the height and width of the concaves are smaller than the thickness of the plasma sheath, the narrow space of the concaves probably restricts the direct production of plasma inside it. Conclusion: The increase of substrate permittivity is beneficial to the production of electrons and chemical species but limits the radial propagation of the plasma along the surface. To generate the plasma directly inside the narrow concaves for the uneven surface of the substrate, the electron density or the width of the concaves should increase.","PeriodicalId":169878,"journal":{"name":"Modern Low Temperature Plasma","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121676315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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