scholarly journals Influence of Controlling Plasma Gas Species and Temperature on Reactive Species and Bactericidal Effect of the Plasma

2021 ◽  
Vol 11 (24) ◽  
pp. 11674
Author(s):  
Yuma Suenaga ◽  
Toshihiro Takamatsu ◽  
Toshiki Aizawa ◽  
Shohei Moriya ◽  
Yuriko Matsumura ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Singlet Oxygen ◽  
Bactericidal Effect ◽  
Nitrogen Plasma ◽  
Reactive Species ◽  
Oh Radicals ◽  
Oh Radical ◽  
Gas Temperature ◽  
Log Reduction ◽  
Carbon Dioxide Plasma

In this study, plasma gas species and temperature were varied to evaluate the reactive species produced and the bactericidal effect of plasma. Nitrogen, carbon dioxide, oxygen, and argon were used as the gas species, and the gas temperature of each plasma was varied from 30 to 90 °C. Singlet oxygen, OH radicals, hydrogen peroxide, and ozone generated by the plasma were trapped in a liquid, and then measured. Nitrogen plasma produced up to 172 µM of the OH radical, which was higher than that of the other plasmas. In carbon dioxide plasma, the concentration of singlet oxygen increased from 77 to 812 µM, as the plasma gas temperature increased from 30 to 90 °C. The bactericidal effect of carbon dioxide and nitrogen plasma was evaluated using bactericidal ability, which indicated the log reduction per minute. In carbon dioxide plasma, the bactericidal ability increased from 5.6 to 38.8, as the temperature of the plasma gas increased from 30 to 90 °C. Conversely, nitrogen plasma did not exhibit a high bactericidal effect. These results demonstrate that the plasma gas type and temperature have a significant influence on the reactive species produced and the bactericidal effect of plasma.

scholarly journals Discrimination of structural isomers of amphetamine using carbon dioxide negative-ion chemical ionization mass spectrometry

1997 ◽  
Vol 13 (2) ◽  
pp. 151-161 ◽  
Author(s):  
Kevin B. Thurbide ◽  
C. M. Elson ◽  
P. G. Sim
Keyword(s):  
Carbon Dioxide ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Negative Ion ◽  
Ionization Mass ◽  
Structural Isomers ◽  
Mass Spectral ◽  
Negative Ion Chemical Ionization ◽  
Spectral Behaviour ◽  
Carbon Dioxide Plasma

The negative‒ion chemical ionization mass spectra of a group of structural isomers of amphetamine have been studied using carbon dioxide as the reagent gas. Characteristic and reproducible differences are observed for each member of the set implying that this technique offers a means of distinguishing among groups of amphetamine isomers. Characteristic adducts to the molecular ion are observed in the form (M–[H]+[O]) and (M–[H]+[CO2]). Descriptions of some fragments are given based on the mass spectral behaviour of a set of analogue compounds and the results of oxygen-18 labelled carbon dioxide reagent gas experiments. Contents of the carbon dioxide plasma and their impact on various analytes is also discussed.

scholarly journals Evolution of Singlet Oxygen by Activating Peroxydisulfate and Peroxymonosulfate: A Review

2021 ◽  
Vol 18 (7) ◽  
pp. 3344
Author(s):  
Guangfeng Xiao ◽  
Tiantian Xu ◽  
Muhammad Faheem ◽  
Yanxing Xi ◽  
Ting Zhou ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Organic Contaminants ◽  
Advanced Oxidation Processes ◽  
Carbon Materials ◽  
Heterogeneous Systems ◽  
Oh Radicals ◽  
Oxygen Species ◽  
Research Gaps ◽  
Research Attention ◽  
Oxidation Properties

Advanced oxidation processes (AOPs) based on peroxydisulfate (PDS) or peroxymonosulfate (PMS) activation have attracted much research attention in the last decade for the degradation of recalcitrant organic contaminants. Sulfate (SO4•−) and hydroxyl (•OH) radicals are most frequently generated from catalytic PDS/PMS decomposition by thermal, base, irradiation, transition metals and carbon materials. In addition, increasingly more recent studies have reported the involvement of singlet oxygen (1O2) during PDS/PMS-based AOPs. Typically, 1O2 can be produced either along with SO4•− and •OH or discovered as the dominant reactive oxygen species (ROSs) for pollutants degradation. This paper reviews recent advances in 1O2 generation during PDS/PMS activation. First, it introduces the basic chemistry of 1O2, its oxidation properties and detection methodologies. Furthermore, it elaborates different activation strategies/techniques, including homogeneous and heterogeneous systems, and discusses the possible reaction mechanisms to give an overview of the principle of 1O2 production by activating PDS/PMS. Moreover, although 1O2 has shown promising features such as high degradation selectivity and anti-interference capability, its production pathways and mechanisms remain controversial in the present literatures. Therefore, this study identifies the research gaps and proposes future perspectives in the aspects of novel catalysts and related mechanisms.

Investigating the NO-dependent photooxidation of limonene by OH and O3 using the atmosphere simulation chamber SAPHIR

2021 ◽  
Author(s):  
Yat Sing Pang ◽  
Martin Kaminski ◽  
Anna Novelli ◽  
Philip Carlsson ◽  
Ismail-Hakki Acir ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Reaction Pathways ◽  
Oh Radicals ◽  
Oh Radical ◽  
Simulation Experiments ◽  
Master Chemical Mechanism ◽  
Simulation Results ◽  
Atmosphere Simulation Chamber

<p>Limonene is the fourth-most abundant monoterpene in the atmosphere, which upon oxidation leads to the formation of secondary organic aerosol (SOA) and thereby influences climate and air quality.</p><p>In this study, the oxidation of limonene by OH at different atmospherically relevant NO and HO<sub>2</sub> levels (NO: 0.1 – 10 ppb; HO<sub>2</sub>: 20 ppt) was investigated in simulation experiments in the SAPHIR chamber at Forschungszentrum Jülich. The analysis focuses on comparing measured radical concentrations (RO<sub>2</sub>, HO<sub>2</sub>, OH) and OH reactivity (k<sub>OH</sub>) with modeled values calculated using the Master Chemical Mechanism (MCM) version 3.3.1.</p><p>At high and medium NO concentrations, RO<sub>2</sub> is expected to quickly react with NO. An HO<sub>2</sub> radical is produced during the process that can be converted back to an OH radical by another reaction with NO. Consistently, for experiments conducted at medium NO levels (~0.5 ppb, RO<sub>2</sub> lifetime ~10 s), simulated RO<sub>2</sub>, HO<sub>2</sub>, and OH agree with observations within the measurement uncertainties, if the OH reactivity of oxidation products is correctly described.</p><p>At lower NO concentrations, the regeneration of HO<sub>2</sub> in the RO<sub>2</sub> + NO reaction is slow and the reaction of RO<sub>2</sub> with HO<sub>2</sub> gains importance in forming peroxides. However, simulation results show a large discrepancy between calculated radical concentrations and measurements at low NO levels (<0.1 ppb, RO<sub>2</sub> lifetime ~ 100 s). Simulated RO<sub>2</sub> concentrations are found to be overestimated by a factor of three; simulated HO<sub>2</sub> concentrations are underestimated by 50 %; simulated OH concentrations are underestimated by about 35%, even if k<sub>OH</sub> is correctly described. This suggests that there could be additional RO<sub>2</sub> reaction pathways that regenerate HO<sub>2</sub> and OH radicals become important, but they are not taken into account in the MCM model.</p>

scholarly journals Influence of Gas Temperature in Atmospheric Non-Equilibrium Plasma on Bactericidal Effect

2018 ◽  
Vol 23 (4) ◽  
pp. 167-175 ◽  
Author(s):  
HIROAKI KAWANO ◽  
TOSHIHIRO TAKAMATSU ◽  
YURIKO MATSUMURA ◽  
HIDEKAZU MIYAHARA ◽  
ATSUO IWASAWA ◽  
...  
Keyword(s):  
Bactericidal Effect ◽  
Gas Temperature ◽  
Equilibrium Plasma ◽  
Non Equilibrium

Power Ultrasound Treatment of Listeria monocytogenes in Apple Cider

2005 ◽  
Vol 68 (11) ◽  
pp. 2333-2340 ◽  
Author(s):  
ADAM R. BAUMANN ◽  
SCOTT E. MARTIN ◽  
HAO FENG
Keyword(s):  
Listeria Monocytogenes ◽  
Saline Solution ◽  
Bactericidal Effect ◽  
Solution Ph ◽  
Power Ultrasound ◽  
Apple Cider ◽  
Log Reduction ◽  
Lethal Temperatures ◽  
First Order Kinetics ◽  
Effects Of Temperature

Inactivation experiments with Listeria monocytogenes 10403S, an ultrasound-resistant strain, were conducted at sublethal (20, 30, and 40°C) and lethal (50, 55, and 60°C) temperatures in saline solution (pH 7.0), acidified saline solution (pH 3.4), and apple cider (pH 3.4) with and without application of ultrasound (20 kHz, 457 mW·ml−1). The survival of recoverable L. monocytogenes 10403S in apple cider was evaluated, and the effects of temperature, ultrasound, pH, and food matrix on inactivation were studied. Application of ultrasound increased the inactivation rate at both sublethal and lethal temperatures. Additional death of L. monocytogenes 10403S was due to low acidity at the lethal temperatures. The reduction in surviving L. monocytogenes 10403S followed first order kinetics at sublethal temperatures, but at lethal temperatures, a two-section linear model described the inactivation behavior. The bactericidal effect of thermosonication was additive in apple cider. The survival tests of L. monocytogenes 10403S in apple cider indicated the possibility of using a mild treatment condition in combination with ultrasound to achieve a 5-log reduction in number of listerial cells.

Boundary Layer Temperature Profile in Diamond CVD System Using Laser-Induced Fluorescence

1995 ◽  
Vol 416 ◽  
Author(s):  
Qingyu Wang ◽  
Jon L. Lindsay ◽  
David L. Hofeldt
Keyword(s):  
Boundary Layer ◽  
Temperature Profile ◽  
Population Distribution ◽  
Substrate Surface ◽  
Plasma Jet ◽  
Laser Induced Fluorescence ◽  
Diamond Growth ◽  
Oh Radicals ◽  
Measured Temperature ◽  
Gas Temperature

ABSTRACTThe gas temperature of a radio-frequency thermal plasma has been measured by laser-induced fluorescence along the axis of the plasma jet near the substrate surface. The temperature was determined from the rotational population distribution of OH radicals. From the measured temperature profile, the freestream temperature was found to be about 3400 K and the boundary layer thickness was determined to be about 1 mm. A numerical model including carbonhydrogen- argon kinetics was used to predict species concentrations near the surface of the substrate. The results indicate that all CHa radical concentrations increase with freestream temperature for temperatures between 2500-4000 K. Of the C1 radicals, methyl has the highest concentration in this range in our system, which is consistent with other reports that methyl is an important diamond growth species.

The new method for the generation of singlet oxygen from water: Bactericidal effect

2012 ◽  
Vol 53 ◽  
pp. S146
Author(s):  
A. Iwasawa⁎ ◽  
Y. Matsumrua ◽  
T. Kamachi ◽  
T. Ozawa ◽  
M. Kohno
Keyword(s):  
Singlet Oxygen ◽  
Bactericidal Effect ◽  
New Method
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