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New and sustainable food processing platforms are urgently needed to address global food safety and preservation challenges. Nonthermal plasma discharges generated within the food packaging, referred to as the in-package plasma, is a highly promising approach. The in-package plasma technique is very effective for bacterial and sporal sterilization with limited thermal and adverse effects on food quality while requiring low energy inputs and no added potentially hazardous food preservatives. This review provides insights into the fundamental mechanisms of food preservation based on the in-package plasma in diverse processing configurations and packaging gas chemistries. The current and emerging state-of-the-art in-package plasma-based food applications and the prevailing microbiological inactivation mechanisms are critically examined. The potential effects on various nutritional, quality attributes and chemical safety of different food products during shelf life are discussed. In-package plasma technology can be utilized to ensure microbial safety, maintain nutritional quality, and prevent cross-contamination of food products. Studies have shown that the in-package plasma effectively inactivates pathogenic microorganisms and inhibits their growth while preserving the quality of fresh and minimally processed foods during shelf life. To overcome the common limitations of current in-package plasma methods arising due to oxidation of lipids and potential packaging material modification by the reactive species, using oxygen-reduced atmospheres in combination with advanced biopolymer materials for plasma packaging are envisaged. Finally, recommendations and directions for future studies and applications are outlined to address the scientific and engineering challenges of this promising food preservation technology. • Critical analysis of recent progress in in-package plasmas for food preservation. • Fundamental physics and chemistry of cold plasmas within food packages. • Evaluation of plasma reactors and processes for in-package food treatment. • Mechanisms of microbial inactivation and food preservation by plasmas. • Outlook for the development of in-package plasma technology. [ABSTRACT FROM AUTHOR]

The production of ammonia, powered by renewable energy, in a decentralized manner is of key importance in the transition to a more sustainable future. Recent research has explored the integration of non-thermal plasma and electrochemical processes to achieve this goal. However, the success of this hybrid process is contingent on the energy efficiency of the plasma-generated species. Herein, we developed a plasma bubble reactor, driven by nanosecond pulses interfacing plasma directly with water. This reactor can comprehensively probe gas ionization processes, different energy channels, corresponding plasma catalytic reaction mechanisms, and reactive species in gas and liquid phases. By using on-and-off plasma ignition with rapid pulses, we could regulate energy consumption in cycles and achieved the lowest reported energy consumption of 2.7 ± 0.1 kWh mol-1 NO 3 − and 3.2 ± 0.1 kWh mol-1 NH 4 + after electrocatalytic nitrate reduction. This provides a promising pathway to producing green, renewable ammonia from air and water. [Display omitted] • Nanosecond pulsed plasma bubbles coupled with electrocatalysis for sustainable ammonia production. • Energy mapping and reaction pathways compared for DBD and SD modes. • SD achieves higher energy density and efficiency of 2.7 ± 0.1 kWh mol-1 NO 3 − (aq). • SD mode in a bubble interface with water generates high-density NO x(aq). [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) is a green oxidant widely used in various fields, from water treatment to rocket propellant. Currently, H2O2 is predominantly manufactured via the anthraquinone process, which requires large infrastructure investments and high energy consumption. In this study, an argon plasma-catalytic bubble process was designed to generate underwater plasma bubbles for efficient delivery of reactive species for H2O2 synthesis, using only water as a reactant and solar radiation as the renewable energy source. The process demonstrates unprecedented energy efficiency by employing a plasma-bubble catalytic reactor capable of operation in two discharge modes, i.e., glow and spark discharges, and using dual reactors within a single AC-circuit to mitigate energy losses around the ground electrode. The results suggest that the principal route of H2O2 generation is from the combination of dissolved ˙OH radicals at the plasma–liquid interface (PLI) of the forming bubbles. The dissolution of H2O2 formed in the gas phase also contributes to aqueous H2O2 generation, especially when employing humid argon. By employing a secondary reactor to utilise the lost energy around the low-voltage electrode and integrating a strongly interfacial-coupled 2D-TiO2/2D-g-C3N4 photocatalyst in the glow discharge area, the achieved H2O2 production rate and energy efficiency of the system are 164.6 mg h−1 and 9.0 g kW h−1, respectively. This study provides new insights for sustainable and decentralised H2O2 production, and the proposed strategy can be further developed as a stand-alone or auxiliary technology in green and sustainable chemistry. [ABSTRACT FROM AUTHOR]

Novel plasma-based technologies that offer maximum efficiency at minimal environmental costs are expected to further promote the sustainable societal and economic development. Unique transfer of chemical reactivity and energy from gaseous plasmas to water takes place in the absence of any other chemicals, but results in a product with a notable transient broad-spectrum biological activity, referred to as plasma-activated water (PAW). These features make PAW a green prospective solution for a wide range of biotechnology applications, from water purification to biomedicine. Here, we present a succinct review of how novel, efficient methods based on non-equilibrium reactive plasma chemistries can be applied to low-cost natural water sources to produce a prospective product with a wide range of applications while at the same time minimising the process steps and dramatically reducing the use of expensive and/or hazardous reagents. Despite the recent exciting developments in this field, there presently is no topical review which specifically focuses on the underlying physics and chemistry related to plasma-activated water. We focus specifically on the PAW generation, origin of reactive species present in PAW, its related analytical chemistry and potentially different mechanisms that regulate the bio-activities of PAW in different biotech-applications and their roles in determining PAW efficacy and selectivity. We then review recent advances in our understanding of plasma-water interactions, briefly outlining current and proposed applications of PAW in agriculture, food and biomedicine. Finally, we outline future research directions and challenges that may hinder translation of these technologies into real-life applications. Overall, this review will provide much needed insights into the fundamental aspects of PAW chemistry required for optimization of the biochemical activity of PAW and translation of this environment- and human-health-friendly, and energy-efficient strategy into real life applications. [ABSTRACT FROM AUTHOR]

Plasma bubbles are regarded as a promising means of interacting plasma discharges and liquids due to their high efficiency in the generation of reactive species. The discharge mode and characteristics are significant factors that should be considered. In this study, the plasmas are initially generated in the gas phase and then driven by the gas flow to diffuse into the solution through the two holes at the lower part of the quartz tube to form plasma bubbles. The discharge modes, characteristics, and plasma–liquid interactions in two different configurations, i.e., bare electrode and dielectric-coated electrode, are investigated. It is found that the discharge mode induced for the two structures is different, with a hybrid-mode operating in the bare electrode design and a filamentary mode operating in the dielectric design. When the applied voltage is increased, a filamentary-to-spark transition occurs in the bare structure, while the discharge remains relatively stable in the dielectric design. Direct and intense contact between the discharge and the solution in the bare structure greatly promotes the physio-chemical reactions and results in obvious changes in H2O2 concentration, solution pH, conductivity, and temperature. This study provides insights into hybrid gas–liquid discharges and reactor design for plasma bubble generation. [ABSTRACT FROM AUTHOR]

Plasma treated water (PTW), produced by atmospheric-pressure plasma treatment of water, usually contains various reactive oxygen and nitrogen species (RONS). This study aimed at evaluating the effectiveness of different types of PTW on seed germination, seedling growth and microbial sterilization during the germinated mung bean processing. Results showed that air-PTW possessed outstanding abilities in improving seed germination and seedling growth with a germination index of 95.50% and a vigor index of 1146.64, and in microbial decontamination. The physicochemical properties of the PTW were analyzed to better understand the PTW stressed germination. Some physiological parameters like the activity of superoxide dismutase (SOD), the contents of malondialdehyde (MDA) and phytohormone (indole acetic acid (IAA) and abscisic acid (ABA)) during germination were also evaluated. This study suggested that air-PTW treatment could indeed provide a green and effective mean of stimulating seed germination and plant growth, and thus accelerate the growth cycle. Increasing the production of food by using both economical and environmentally friendly means has been deemed as an urgent matter to sustain the food demand of rapidly growing world population. The results of this study suggest that PTW presents a great opportunity to address this need by increasing seedling growth and viability. PTW treatment is an environment-friendly and low-cost mean of stimulating seed germination and plant growth, which possesses the potential of scale up or industrial applications in relevant fields. Unlabelled Image • Plasma-treated water (PTW) was applied into mung bean germination for the first time. • The effects of PTW on seed germination, seedling growth, and sprout sterilization were studied. • Air-PTW has the potential for use as a green and effective mean for improving seed germination. [ABSTRACT FROM AUTHOR]

The socio-economic, environmental, and health implications of diseases caused by pathogenic microorganisms and their treatment using conventional antimicrobials are significant. The increasing resistance to antibiotics and detrimental biological side effects of many common antibiotics on human health and on the ecosystem have driven the search for new cost-effective and highly-efficient sterilization treatments and agents that are more environmentally benign. Plasma activated water (PAW), a product of cold atmospheric plasma reacting with water, is a promising broad-spectrum biocidal agent whose biochemical activity is attributed to the presence of a rich diversity of highly reactive oxygen and nitrogen species (RONS). The transient activity of PAW, where PAW reverts to water within days of storage and application, suggests that it can become a green alternative to conventional chemical treatment methods, yet the issues of scale up and the not fully understood mechanism of activity remain. In this study, we sought to explore the antibiotic potential of PAW generated from a plasma jet in a continuous flow reactor and determine the individual and combined contribution of thus-generated reactive chemistries in PAW for organism inactivation. Treatment of Escherichia coli with PAW led to more than a 4-log reduction, while exposure to an equivalent single dose of hydrogen peroxide (H2O2), nitrate (NO3−) or nitrite (NO2−) to that found in PAW failed to attain the same level of reduction. Peroxynitrite was identified as a critical bioactive species, particularly under acidic conditions, originating from the synergistic plasma effects (like the reactions of H2O2, NO3−, NO2− and other existing short-lived species like OH radicals in PAW). This research successfully demonstrated the possibility of PAW being an effective environmentally benign disinfectant, the activity of which is closely linked to the generation of peroxynitrite, providing much needed insights into the fundamental aspects of PAW chemistry required for optimisation of the biochemical activity of PAW and translation of this decontamination strategy into real life applications. [ABSTRACT FROM AUTHOR]

Pesticides are widely used in commercial goji Lycium barbarum cultivation to prevent damage of the delicate fruits by insects, potentially leading to insecticide and fungicide residues at levels dangerous to human health. In this study, removal of organophosphorus pesticide (OP) residues (i.e. omethoate and dichlorvos) from the surface of L. barbarum was conducted using a gas phase surface discharge (GPSD) plasma system. ICCD and GC–MS measurements showed that a homogeneous and uniform GPSD glow-like plasma could be achieved and the efficiency of OP residues degradation greatly depended on the applied voltage and plasma exposure time, with 99.55% and 96.83% efficiency recorded for omethoate and dichlorvos (DDVP), respectively after 30 min GPSD plasma exposure at the discharge voltage of 10 kV. FT-IR and chemical analysis of the intermediates produced during GPSD exposure revealed that the omethoate and DDVP molecules could be completely degraded into nontoxic species, at the appropriate dosage of GPSD plasma exposure, without compromising the quality of L. barbarum . Based on the experimental and simulation results, a mechanism of OP degradation attributed to energetic electrons and highly reactive species generated by GPSD plasma was proposed. [ABSTRACT FROM AUTHOR]

The interactions between plasma‐generated excited particles and water play an integral role in sustainable degradation of pharmaceutical compounds, improving aerobic respiration of activated sludge, and efficient removal of microorganisms from water, and are fundamental to the intentional transfer of reactivity from plasmas to biological solutions for such medical applications as cancer treatment and wound healing. The physical and chemical mechanisms that govern this transfer of reactivity are complex, and include concomitant generation and consumption of species in the gas and liquid phases, and at the interface. As such, it is challenging to predict the quantities of biologically‐active radicals and molecules in liquid phase from gas phase measurements alone. Rapid and accurate quantification of reactive species, such as OH radicals and H2O2 molecules within the liquid phase and their link to specific biological effects is therefore critical for medical applications of plasma‐activated solutions. Using a simple, low‐cost method for trapping and stabilization of OH radicals by means of salicylic acid, this work seeks to provide further insights into the physics and chemistry of generation of OH radicals within the liquid phase, and integrate these findings with decontamination outcomes for four commonly used processing gases. [ABSTRACT FROM AUTHOR]

Solution pH is a significant parameter that affects the electrical characteristics of gas–liquid discharges and thus potentially produces different plasma chemistries for different plasma-engineered applications. In this study, the discharge characteristics and long-lived aqueous reactive species under different initial pH conditions were investigated. It was found that the discharge contained three phases in one pulse cycle, which occurred at the pulse rising edge, the falling edge, and between the rising and falling edges. The discharge intensity and average power at an initial solution pH of 7.0 are much lower than those obtained at an initial solution pH of 5.0 and 9.0. In contrast, the density ratio of N2 (C3Πu, v = 1)/N2 (C3Πu, v = 0) is much higher under neutral solution conditions, indicating that the relatively high vibrational energy was obtained in the gas–liquid discharge plasma. Concentrations of aqueous species H2O2, NO2–, and NO3– are higher at the initial pH of 9.0, indicating that different plasma intensities and chemical compositions (H+ and OH–) are involved in their generation and consumption processes. This study provides insights into understanding and controlling the characteristics of the gas–liquid discharge under different solution conditions. [ABSTRACT FROM AUTHOR]

In this study, liquid-phase microplasma technology (LPMPT) was employed to facilitate the liquefaction of bamboo shoot shell (BSS) in polyethylene glycol 400 (PEG 400) and ethylene glycol (EG) mixture. Effects of liquefaction conditions such as liquefaction time, catalyst percentage, solvent/BSS mass ratio, PEG/EG volume ratio on liquefaction were investigated experimentally. The results showed that the introduction of LPMPT significantly shortened the liquefaction time to 3 min without extra heating. The liquefaction yield reached 96.73% under the optimal conditions. The formation of massive reactive species and instantaneous heat accumulation both contributed to the rapid liquefaction of BSS. Thus, LPMPT could be considered as a simple and efficient method for the assistance of biomass fast liquefaction. [ABSTRACT FROM AUTHOR]

Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS). Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma. [ABSTRACT FROM AUTHOR]

In this study, the effect of atmospheric-pressure air surface dielectric barrier discharge (SDBD) on the degradation of Omethoate smeared edible wolfberry was investigated by gas chromatography and mass spectrometry (GC-MS). The degradation efficiency of SDBD on Omethoate is shown to be strongly dependent on the discharge voltage and plasma treatment time. The plasma-induced degradation mechanisms were studied through identification of the intermediates or by-products generated during SDBD plasma treatment. The results show that the degradation efficiency may be higher than 99% under the optimum discharge conditions, i.e., at the applied voltage of 10 kV and the treatment time of 30 min. It is concluded that the atmospheric-pressure SDBD plasma may degrade pesticide residue into nontoxic species (such as PO43−, H2O, SO42−, and CO2) during the plasma treating process. [ABSTRACT FROM AUTHOR]

A self-made microplasma jet array device is used to treat deoxyadenosine (dA) and adenosine (Ado) solutions to avoid the effect of air on genetic materials. Results show that Ado is easily converted into dA through deoxidation reaction. In addition, dA solution is treated with different microplasma arrays (i.e., atmospheric-pressure Ar, N2, air, and O2­) for comparative analysis. The dA molecule is relatively stable within the Ar plasma for 3 min treatment time. This molecule can be modified into different structures with N2, air, and O2 microplasma arrays. The results obtained in this study provide references for the application of plasma in biology and the effect of oxygen-containing free radicals in biological plasma. [ABSTRACT FROM AUTHOR]

Antibiotics have been extensively used as pharmaceuticals for diverse applications. However, their overuse and indiscriminate discharge to water systems have led to increased antibiotic levels in our aquatic environments, which poses risks to human and livestock health. Non-thermal plasma water. However, the issues of process scalability and the mechanisms towards understanding the plasma-induced degradation remain. This study addresses these issues by coupling a non-thermal plasma jet with a continuous flow reactor to reveal the effective mechanisms of amoxicillin degradation. Four industry-relevant feeding gases (nitrogen, air, argon, and oxygen), discharge voltages, and frequencies were assessed. Amoxicillin degradation efficiencies achieved using nitrogen and air were much higher compared to argon and oxygen and further improved by increasing the applied voltage and frequency. The efficiency of plasma-induced degradation depended on the interplay of hydrogen peroxide (H 2 O 2) and nitrite (NO 2 −), validated by mimicked chemical solutions tests. Insights into prevailing degradation pathways were elucidated through the detection of intermediate products by advanced liquid chromatography-mass spectrometry. [Display omitted] • New amoxicillin degradation method using nitrogen, argon, air, and oxygen plasmas. • First-time revealed order of degradation efficiency: nitrogen＞air＞argon＞oxygen. • New mechanism of amoxicillin degradation based on plasma reactive nitrogen species. • Advanced mass spectrometry related intermediates to degradation pathways. • Scalable approach for plasma deactivation of amoxicillin in wastewater. [ABSTRACT FROM AUTHOR]

Antibiotics have been extensively used as pharmaceuticals for diverse applications. However, their overuse and indiscriminate discharge to water systems have led to increased antibiotic levels in our aquatic environments, which poses risks to human and livestock health. Non-thermal plasma water. However, the issues of process scalability and the mechanisms towards understanding the plasma-induced degradation remain. This study addresses these issues by coupling a non-thermal plasma jet with a continuous flow reactor to reveal the effective mechanisms of amoxicillin degradation. Four industry-relevant feeding gases (nitrogen, air, argon, and oxygen), discharge voltages, and frequencies were assessed. Amoxicillin degradation efficiencies achieved using nitrogen and air were much higher compared to argon and oxygen and further improved by increasing the applied voltage and frequency. The efficiency of plasma-induced degradation depended on the interplay of hydrogen peroxide (H 2 O 2) and nitrite (NO 2 −), validated by mimicked chemical solutions tests. Insights into prevailing degradation pathways were elucidated through the detection of intermediate products by advanced liquid chromatography-mass spectrometry. [Display omitted] • New amoxicillin degradation method using nitrogen, argon, air, and oxygen plasmas. • First-time revealed order of degradation efficiency: nitrogen＞air＞argon＞oxygen. • New mechanism of amoxicillin degradation based on plasma reactive nitrogen species. • Advanced mass spectrometry related intermediates to degradation pathways. • Scalable approach for plasma deactivation of amoxicillin in wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Underwater plasma bubbles were used to degrade cefixime in water. • Complete cefixime degradation with high-energy yield of 1.5 g/kWh. • Degradation of cefixime was conducted by reactive species, especially short-lived OH radicals. • Degradation pathways of cefixime were proposed by intermediates identified by LCMS. • Plasma treatment leads to the loss of antibacterial activity and cytotoxicity of cefixime. Excessive use and indiscriminate discharge of antibiotics inevitably lead to their accumulation in the environment, posing significant ecological and physiological risks. Non-thermal plasma (NTP) is receiving increasing attention as a sustainable technology for the efficient breakdown of these antibiotics as well as other contaminants. However, implementation of NTP technology still faces several hurdles, particularly the maximization of the reactive plasma effects and the practical scaling approaches. In this study, we generated NTP inside forming bubbles with enlarged gas-liquid interfacial areas for efficient delivery of reactive plasma species to target cefixime antibiotic molecules in aqueous solution. The degradation of cefixime was largely dependent on the different number of microholes, air flow rate, discharge power, plasma exposure time and solution properties. Results show that a high-performance degradation was achieved in the 10-microhole reactor with an energy yield of 1.5 g/kWh, after 30 min of plasma treatment. Based on LC-MS analysis, an NTP-initiated cefixime degradation pathway was proposed. Cytotoxicity studies demonstrated that the antibiotic activity of cefixime was effectively and wholly deactivated by the plasma process, and that no toxic effects of the 30 min-treated water were observed toward human cell lines. Furthermore, considering that air was employed as the inducer gas, which results in the formation of reactive nitrogen species in the water, the treated water was able to enhance seedling growth, further contributing to the societal and economic benefits of this plasma-based antibiotic degradation strategy. [ABSTRACT FROM AUTHOR]

• The current state-of-the-art of plasma-enabled ammonia synthesis is summarized. • The fundamental physio-chemistry of plasma activation of feedstocks is provided. • The mechanisms for the reaction dynamics of reactive species are concluded. • Opportunities and challenges for the plasma-ammonia industry are outlined. Ammonia is one of our most important industrial chemicals supporting the global food supply as the major crop fertilizer. Moreover, it is increasingly being promoted as a promising carbon-free fuel source, and an energy storage and transportation medium. However, the current approach for ammonia synthesis, known as the Haber-Bosch process, requires large-scale infrastructure preventing the designs of decentralization. The process consumes a large fossil fuel input leading it to be a major source of CO 2 emissions. Plasma-enabled ammonia synthesis provides a clean, sustainable and flexible alternative, where the process is driven by the use of plasmas that activate the source gas(es). However, atmospheric plasmas are complex due to their highly reactive environment (energetic electrons, reactive oxygen and nitrogen species, UV photons, electric field effects, and others), resulting in a challenging scientific issue for both plasma researchers and chemical engineers. The review summarizes the current state-of-the-art of plasma-enabled ammonia synthesis, and provides insights into the fundamental physio-chemistry of plasma activation, including the excitation, dissociation and ionization of feedstocks, as well as the underlying mechanisms for the reaction dynamics of reactive species in the highly-reactive plasma environment. Finally, the opportunities and challenges for this plasma-enabled technology are outlined to approach a sustainable and flexible ammonia industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Underwater plasma bubbles were used to degrade cefixime in water. • Complete cefixime degradation with high-energy yield of 1.5 g/kWh. • Degradation of cefixime was conducted by reactive species, especially short-lived OH radicals. • Degradation pathways of cefixime were proposed by intermediates identified by LCMS. • Plasma treatment leads to the loss of antibacterial activity and cytotoxicity of cefixime. Excessive use and indiscriminate discharge of antibiotics inevitably lead to their accumulation in the environment, posing significant ecological and physiological risks. Non-thermal plasma (NTP) is receiving increasing attention as a sustainable technology for the efficient breakdown of these antibiotics as well as other contaminants. However, implementation of NTP technology still faces several hurdles, particularly the maximization of the reactive plasma effects and the practical scaling approaches. In this study, we generated NTP inside forming bubbles with enlarged gas-liquid interfacial areas for efficient delivery of reactive plasma species to target cefixime antibiotic molecules in aqueous solution. The degradation of cefixime was largely dependent on the different number of microholes, air flow rate, discharge power, plasma exposure time and solution properties. Results show that a high-performance degradation was achieved in the 10-microhole reactor with an energy yield of 1.5 g/kWh, after 30 min of plasma treatment. Based on LC-MS analysis, an NTP-initiated cefixime degradation pathway was proposed. Cytotoxicity studies demonstrated that the antibiotic activity of cefixime was effectively and wholly deactivated by the plasma process, and that no toxic effects of the 30 min-treated water were observed toward human cell lines. Furthermore, considering that air was employed as the inducer gas, which results in the formation of reactive nitrogen species in the water, the treated water was able to enhance seedling growth, further contributing to the societal and economic benefits of this plasma-based antibiotic degradation strategy. [ABSTRACT FROM AUTHOR]

Sustainable ammonia synthesis under mild conditions that relies on renewable energy sources and feedstocks is globally sought to replace the current Haber–Bosch process. Electricity-driven plasma catalysis is receiving increasing attention as a sustainable technology for the efficient synthesis of ammonia. However, the current implementation of nonthermal plasma technology still faces several hurdles, particularly the extensive usage of energy-intensive H2, low energy efficiency and the lack of understanding of the underlying mechanisms of the plasma catalysis process. Here we propose a green chemical pathway of plasma catalysis from nitrogen and water for sustainable ammonia production. In order to understand the different characteristics of the N2/H2O plasma system and seek further improvements in ammonia synthesis, detailed plasma kinetics modelling is presented in comparison with the N2/H2 system at atmospheric pressure. The model includes both electron and vibrational kinetics and updated surface reactions adapted from DFT calculation results on the SiO2 surface. The facile dissociative adsorption of H2O and the Eley–Rideal mechanisms are demonstrated to be important to enable efficient NH3 production as the experimental observation. The model reproduced the measured trends of ammonia production on the different concentrations of H2O input and power density with reasonable accuracy and provided an explanation of the critical influence of temperature and catalyst packing in the N2/H2O system in comparison to the N2/H2 system in relation to the quenching effect of H2O by vibrational–translational relaxation. [ABSTRACT FROM AUTHOR]

Atmospheric pressure plasma jet arrays can expand the treatment dimension of a single jet to large scales effectively, and the arrays with a good downstream uniformity have a great potential for applications in the materials surface treatment and biomedicine. In this paper, a linear-field jet array with a ring-ring electrode structure in Ar is excited by alternating current (AC) and nanosecond (ns) pulse voltage, and the characteristics and downstream uniformity of the array and their dependence on the applied voltage and gas flow rate are investigated and compared through optical, electrical, and Schlieren diagnosis. The electrical and hydrodynamic interactions between the jets in the array are analyzed and discussed. The results show that the ns pulse excited jet arrays can generate relatively large-scale plasma with better uniformity, longer plumes, and higher intensity active species with a higher energy efficiency than the AC excited ones. No visible deviation of the plume and gas flow trajectories in the light emission and Schlieren images is observed for the ns pulse excited arrays. On the other hand, deviation of plume trajectories is shown to depend on the applied voltage and the gas flow rate for the AC excited arrays. The shorter duration of the interaction of the ns pulse excited jet arrays compared with that of the AC excited jet arrays results in the weaker effects of the Coulomb repellence force and the gas heating, which helps to maintain the uniformity of jet arrays. The reported results can help to design controllable and scalable plasma jet arrays in the economic Ar with good uniformity and higher energy efficiency for material surface and biomedical treatments. [ABSTRACT FROM AUTHOR]

Simple Summary: Cold atmospheric plasma (CAP) and plasma-activated medium (PAM) are known to selectively kill cancer cells, however the efficacy of CAP in cancer cells following epithelial-mesenchymal transition (EMT), a process which endows cancer cells with increased stemness, metastatic potential, and resistance to conventional therapies, has not been previously examined. We have used several established models of EMT to show that PAM is significantly more active in cancer cells exhibiting EMT than their epithelial counterparts. We further show that this enhancement correlated with increased levels of reactive oxygen species (ROS) in the mesenchymally-shifted cell lines. Cold atmospheric plasma (CAP) has emerged as a highly selective anticancer agent, most recently in the form of plasma-activated medium (PAM). Since epithelial–mesenchymal transition (EMT) has been implicated in resistance to various cancer therapies, we assessed whether EMT status is associated with PAM response. Mesenchymal breast cancer cell lines, as well as the mesenchymal variant in an isogenic EMT/MET human breast cancer cell system (PMC42-ET/LA), were more sensitive to PAM treatment than their epithelial counterparts, contrary to their responses to other therapies. The same trend was seen in luminal muscle-invasive bladder cancer model (TSU-Pr1/B1/B2) and the non-muscle-invasive basal 5637 bladder cancer cell line. Three-dimensional spheroid cultures of the bladder cancer cell lines were less sensitive to the PAM treatment compared to their two-dimensional counterparts; however, incrementally better responses were again seen in more mesenchymally-shifted cell lines. This study provides evidence that PAM preferentially inhibits mesenchymally-shifted carcinoma cells, which have been associated with resistance to other therapies. Thus, PAM may represent a novel treatment that can selectively inhibit triple-negative breast cancers and a subset of aggressive bladder cancers, which tend to be more mesenchymal. Our approach may potentially be utilized for other aggressive cancers exhibiting EMT and opens new opportunities for CAP and PAM as a promising new onco-therapy. [ABSTRACT FROM AUTHOR]

Non-thermal plasma coupling with photocatalyst is recognized as a promising technology for the degradation of antibiotics, and improving the photocatalyst performance is one of the most significant strategies to improve the efficiency of plasma-catalytic systems. This study employed a nanosecond pulsed gas–liquid discharge coupled with plasma-functionalized TiO2 to achieve a high efficiency of tetracycline degradation and clarify the synergistic mechanism of nanosecond pulse discharge coupling with functionalized TiO2. Results showed that the degradation efficiency with functionalized TiO2 increased by 20% compared to the untreated TiO2 for 4 min-plasma treatment. It is also suggested that the effect of photogenerated holes and electrons can be promoted in the functionalized TiO2, as evidenced by the radical quenching experiments. The plasma-modified TiO2 catalysts were proven to have a good stability and recyclability. This study provides a new sustainable approach to enhance the performance of photocatalysts in the plasma system for environmental remediation. [ABSTRACT FROM AUTHOR]

Complete degradation of mixtures of organic pollutants is a major challenge due to their diverse degradation pathways. In this work, a novel microplasma bubble (MPB) reactor was developed to generate plasma discharges inside small forming bubbles as an effective mean of delivering reactive species for the degradation of the target organic contaminants. The results show that the integration of plasma and bubbles resulted in efficient degradation for all azo, heterocyclic, and cationic dyes, evidenced by the outstanding energy efficiency of 13.0, 18.1 and 22.1 g/kWh with 3 min of processing, in degrading alizarin yellow (AY), orange II (Orng-II) and methylene blue (MB), individually. The MPB treatment also effectively and simultaneously degraded the dyes in their mixtures such as AY + Orng-II, AY + MB and AY + Orng-II + MB. Scavenger assays revealed that the short-lived reactive species, including the hydroxyl (OH) and superoxide anion (O 2 −) radicals, played the dominant role in the degradation of the pollutants. Possible degradation pathways were proposed based on the intermediate products detected during the degradation process. The feasibility of this proposed strategy was further evaluated using other common water pollutants. Reduced toxicity was confirmed by the observed increases in human cell viability for the treated water. This work could support the future development of high performance- and energy-efficient wastewater abatement technologies. Unlabelled Image • A plasma bubble column was developed for pollutant degradation. • Underwater microplasma bubbles facilitated mass transfer of reactive species. • Efficient and simultaneous degradation of dye mixtures was demonstrated. • Outstanding energy efficiency for pollutant degradation was obtained. [ABSTRACT FROM AUTHOR]

• Underwater plasma bubbles facilitated mass transfer of highly reactive species. • Plasma catalytic bubbles using CeO 2 enhanced the AP removal efficiency. • Catalytic performance and durability of CeO 2 were improved by plasma activation. • Degradation mechanisms of AP were proposed by intermediates identified by LCMS. Interactions between effects generated by non-thermal plasma (NTP) and catalysts are increasingly investigated, ranging from energy conversion and material synthesis to pollutant degradation (e.g. volatile organic compounds, VOCs) and water purification. To make the water ecosystem more environmentally and economically sustainable, green and efficient wastewater treatment technologies are urgently required. In this study, a plasmacatalytic bubble column reactor was designed to generate underwater plasma bubbles (PBs) for efficient delivery of plasma-produced gaseous reactive oxidative species to the liquid phase for subsequent applications. This system shows great potential for degrading a stubborn water contaminant azophloxine (AP), which was further enhanced with an addition of CeO 2 catalysts, resulting in the catalytic oxidation of the azo dyes. Moreover, the performances and durability of CeO 2 were further improved via plasma pre-activation. The plasma-treated CeO 2 (CeO 2 -P) displayed a combination of favourable properties, such as a higher concentration of oxygen vacancies and Ce3+ (observed by XPS), a narrowed energy bandgap, and an increased specific surface area (by 41.39%). Compared with the sole PBs and PBs/CeO 2 systems, the highest removal efficiency and kinetic constant up to 99.5% and 0.907 min−1, respectively, were achieved in the PBs/CeO 2 -P system. Reactive species trapping corroborated that ·OH and ·O 2 – played an integral part in AP degradation. Finally, intermediates in the process of AP degradation were identified and a degradation pathway was proposed. This research would offer a promising remediation methodology for water purification via the integration of underwater plasma bubbles and CeO 2 catalysts. [ABSTRACT FROM AUTHOR]

Microbial food contamination can be caused by bacteria, viruses or protozoa at different stages during food processing and storage. The resulting foodborne disease in humans are common and can be severe, especially in children, the elderly or immunocompromised persons. Several viruses have been recognised to account for a large proportion of foodborne illnesses, including human norovirus (HNoV) and hepatitis A virus (HAV). Disinfection methods are needed in all areas of the food processing environment and cold atmospheric plasma (CAP) has emerged as a new technology with antimicrobial activity. CAP is generated by applying an electric field to a gas causing the formation of many active species including reactive oxygen and nitrogen species. This review evaluates the available data on CAP as a potential use for the inactivation of foodborne viruses, including studies using surrogates. We demonstrate the different types of CAP delivery for virus inactivation, including direct and indirect treatments using dielectric barrier discharges (DBD), atmospheric pressure plasma jets (APPJ) and plasma-activated water (PAW). The effect of particular CAP species and the resulting mode of action is also discussed. CAP can successfully inactivate foodborne viruses and its potential as a non-toxic, residue-free sanitation system for fresh foods makes it highly attractive to the industry. However, the lack of standard devices or protocols makes it difficult to meaningfully translate findings. Thus, we propose future research steps that are necessary for upscaling, dose standardisation and following translation to the industry in the near future. • Cold atmospheric plasma (CAP) can successfully inactivate foodborne viruses. • Reactive oxygen and nitrogen species are important for viral inactivation. • Non-toxic, residue-free sanitation system is highly attractive to the food industry. • Standardisation of devices and treatment protocols is necessary for upscaling. [ABSTRACT FROM AUTHOR]

• New effective approach for lignin depolymerisation into renewable chemicals. • Energy-efficient, scalable biomass conversion enabled by low-temperature plasmas. • Fenton reaction assisted high conversion yield under industry relevant conditions. • Chemical industry-sought product rich in aromatics and dicarboxylic acids. Lignin valorisation into renewable fuels and platform chemicals is desirable but still encounters major challenges due to lignin's recalcitrant structure, and the lack of cost-, energy-, and material efficient conversion processes. Herein, we report a low-temperature plasma-based route to lignin depolymerisation at mild conditions. The discharge over ethanol surface locally creating a high-energy and reactive environment rich in free electrons, energetic H radicals, and other reactive species, is well suited for lignin depolymerisation. Furthermore, assisted with a Fenton reaction (by adding Fe 2 O 3 and H 2 O 2) to sustain a more oxidative environment, the lignin conversion yield increases from 42.6% to 66.0%. Thus-obtained renewable chemicals are rich in aromatics and dicarboxylic acid derivatives. The proposed strategy on intensifying reactive chemistry by high-power plasmas enables an effective power-to-chemicals conversion of lignin and may provide useful guidelines for modern biorefineries. [ABSTRACT FROM AUTHOR]

• New approach for clean hydrogen energy and smart nano-carbons production. • Effective bioresource conversion using new pulsed plasma modes. • Catalyst-free, plasma conversion of ethanol at near-room temperature. • Towards full bioresource utilization: carbon for carbon, hydrogen for hydrogen. Selective conversion of bio-renewable ethanol under mild conditions especially at room temperature remains a major challenge for sustainable production of hydrogen and valuable carbon-based materials. In this study, adaptive non-thermal plasma is applied to deliver pulsed energy to rapidly and selectively reform ethanol in the absence of a catalyst. Importantly, the carbon atoms in ethanol that would otherwise be released into the environment in the form of CO or CO 2 are effectively captured in the form of carbon dots (CDs). Three modes of non-thermal spark plasma discharges, i.e. single spark mode (SSM), multiple spark mode (MSM) and gliding spark mode (GSM), provide additional flexibility in ethanol reforming by controlling the processes of energy transfer and distribution, thereby affecting the flow rate, gas content, and energy consumption in H 2 production. A favourable combination of low temperature (<40 °C), attractive conversion rate (gas flow rate of ~120 mL/min), high hydrogen yield (H 2 content >90%), low energy consumption (~0.96 kWh/m3 H 2) and the effective generation of photoluminescent CDs (which are applicable for bioimaging or biolabelling) in the MSM indicate that the proposed strategy may offer a new carbon-negative avenue for comprehensive utilization of alcohols and mitigating the increasingly severe energy and environmental issues. [ABSTRACT FROM AUTHOR]

A plasma's working gas is a significant factor affecting their discharge characteristics and the induced chemistries during plasma–water interactions. However, the effects on the discharge mode and discharge stability have not been fully investigated. This study focuses on the discharge mode transition and stability with nitrogen and oxygen gases. Compared with the oxygen discharge, the nitrogen discharge remained stable over a larger voltage range and long duration time. A diffuse mode discharge had better stability and lower plasma activity for both nitrogen and oxygen gases, whereas a transient spark mode in nitrogen and filament mode in oxygen had lower stability but a higher plasma activity. This study improves the understanding of the physicochemical processes of plasma–water interactions. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate that atmospheric air plasma bubbles are an effective, energy‐efficient, residue‐free alternative to current decontamination techniques. Five to fifteen minutes of plasma‐bubble treatments of inoculated chicken skin led to a significant reduction in colony‐forming units (CFUs). We show that the activation efficiency is dependent on the plasma discharge frequency, with a higher one (2,000 Hz) leading to a higher CFU reduction (1.4 log) as compared with a lower (0.3 log) reduction at 1,000 Hz. Scanning electron microscopy pictures of treated bacteria reveal damage to the cells. An evaluation of the physicochemical properties of the generated plasma‐activated water revealed an increase in conductivity and in ozone, nitrite, nitrate, hydroxyl, and peroxide concentrations with higher frequencies, all contributing to the observed antimicrobial effect. [ABSTRACT FROM AUTHOR]

Plasma‐activated solutions (PAS) are attracting attention in biomedicine, however their complexity necessitates a greater understanding of both the plasma activation process and the selected starting solution. Here, five solutions, including deionized water, saline, PB, PBS, and RPMI 1640, were treated to investigate the physicochemical properties and anticancer effects. The findings show that the different solutions largely affected the gas–liquid interaction reactions and the color penetration distribution of H2O2 and NO2−. The anticancer effects are in the order of DI > PB≈saline> PBS > RPMI 1640, attributed to the important role of H2O2 and NO2− in inactivating cancer cells. This study provides insights into designing and applying PAS in practical anticancer therapy. [ABSTRACT FROM AUTHOR]

Atmospheric-pressure plasma and TiO2 photocatalysis have been widely investigated separately for the management and reduction of microorganisms in aqueous solutions. In this paper, the two methods were combined in order to achieve a more profound understanding of their interactions in disinfection of water contaminated by Escherichia coli. Under water discharges carried out by microplasma jet arrays can result in a rapid inactivation of E. coli cells. The inactivation efficiency is largely dependent on the feed gases used, the plasma treatment time, and the discharge power. Compared to atmospheric-pressure N2, He and air microplasma arrays, O2 microplasma had the highest activity against E. coli cells in aqueous solution, and showed >99.9% bacterial inactivation efficiency within 4 min. Addition of TiO2 photocatalytic film to the plasma discharge reactor significantly enhanced the inactivation efficiency of the O2 microplasma system, decreasing the time required to achieve 99.9% killing of E. coli cells to 1 min. This may be attributed to the enhancement of ROS generation due to high catalytic activity and stability of the TiO2 photocatalyst in the combined plasma-TiO2 systems. Present work demonstrated the synergistic effect of the two agents, which can be correlated in order to maximize treatment efficiency. [ABSTRACT FROM AUTHOR]

Uniform and stable reactivity of atmospheric pressure plasmas is a prerequisite for most applications in fields ranging from materials' surface processing, environment protection, to energy conversion. Dielectric barrier discharges (DBDs) are among the most promising plasmas to satisfy these requirements. However, the unpredictable and uncontrollable transitions between discharge modes, the limited understanding of the DBD ignition and extinction processes, and the complexity of plasma chemistries and reactions with admixture gases restrict their adoption in industry. Here, we report a practically relevant and elegant solution based on using customized nanosecond (ns) pulse excitation and precise addition of oxygen to an Ar flow. The effects of ns pulses and oxygen on the uniformity and reactivity of the DBD are investigated via quantifying the gap voltage Ug and the discharge current Ig from the current–voltage measurements and quantitative discharge imaging. The electron density, ne, is estimated with Ug and Ig. With increasing Ug, more electron avalanches are ignited and overlap, which facilitate ne, Te, and discharge uniformity, while high Ug induces excessive electrons generated with high ionization rates, resulting in the distortion of the space electric field and reduced stability and uniformity. A small amount of added oxygen favors the production of electrons. Overdosed oxygen molecules capture electrons causing a drop in ne and Te and couple with the effect of the electrical field resulting in the filamentary discharges or complete plasma extinction. The mechanism of the effects of ns pulses and oxygen addition on the uniformity and reactivity of plasmas is based on the electrical measurements and discharge image analysis and is cross-validated by optical emission spectra measurements and the ratio of the Ar intensities' calculations as indicators of the variation in ne and Te. The results in this work contribute to the realization and controllability of uniform, stable, and reactive plasmas at atmospheric pressure. [ABSTRACT FROM AUTHOR]

Graphical abstract The PEL process ((a) sawdust and cellulose, (b) corn cob and holocellulose, (c) corn stalk and lignin, (d) rice straw, (e) brief schematic diagram of PEL experimental apparatus, (f) gas product, (g) liquid product, (h) solid residue). Highlights • Discharge characteristics and catalytic efficiency of four catalysts were compared. • The liquefaction yield of sawdust reached 97.20% in 2 min. • A high liquefaction yield was obtained in the presence of a salt catalyst. • Cellulose, holocellulose, and lignin were extracted and liquefied successfully. • Plasma electrolytic technology could successfully liquefy lignocellulosic biomass. Abstract In this research, we compared the discharge characteristics and catalytic efficiency of sulfuric acid, p-toluenesulfonic acid, and their respective sodium salts (sodium sulfate and sodium p-toluenesulfonate) in sawdust liquefaction and found that sulfuric acid was the optimal catalyst when glycerol was used as solvent during the plasma electrolytic liquefaction (PEL) process. When sodium p-toluenesulfonate was used as the only catalyst, the liquefaction yield reached 83.51% after 25 min. This yield was higher than that obtained using sodium sulfate as the catalyst (60.63%) because different concentrations of H ions were produced in PEL. Cellulose, lignin, and holocellulose were extracted from sawdust and successfully liquefied in PEL, illustrating the universality of PEL. The optical emission spectra of the different biomass during the PEL process were similar, indicating that the kinds of free radicals produced were similar, which can accelerate the liquefaction of sawdust. [ABSTRACT FROM AUTHOR]

Plasma-activated hydrogels have promising application prospects in the field of transdermal penetration therapy, such as subcutaneous tumours, due to their long-lasting, slow-release properties and ability to be easily applied to skin. In this study, surface air plasma was used to prepare plasma-activated Aristoflex AVC hydrogel (PAH) and plasma-activated water (PAW) by irradiation. The characteristics of PAH and PAW were further studied in terms of reactive oxygen species (ROS) storage, transdermal permeation, and in vitro anticancer effects in an artificial skin model. The experimental results showed that PAH had a prolonged storage time of ROS and more transdermal permeation of ROS through artificial skin in Franz diffusion cell after 30 h compared to PAW, which means PAH could be superior to PAW for long-term applications on the skin surface. The in vitro anticancer effects of PAH in an artificial skin model were also better than those of PAW, reducing the viability of A375 cells without causing damage to HaCaT cells. Our study shows that PAH is superior to PAW in body-surface coating applications and can be used for subcutaneous anticancer applications. [ABSTRACT FROM AUTHOR]

A continuous risk from microbial infections poses a major environmental and public health challenge. As an emerging strategy for inhibiting bacterial infections, plasma‐activated water (PAW) has proved to be highly effective, environmental‐friendly, and non‐drug resistant to a broad range of microorganisms. However, the relatively short lifetime of reactive oxygen and nitrogen species (RONS) and the high spreadability of liquid PAW inevitably limit its real‐life applications. In this study, plasma‐activated hydrogel (PAH) is developed to act as reactive species carrier that allow good storage and controlled slow‐release of RONS to achieve long‐term antibacterial effects. Three hydrogel materials, including hydroxyethyl cellulose (HEC), carbomer 940 (Carbomer), and acryloyldimethylammonium taurate/VP copolymer (AVC) are selected, and their antibacterial performances under different plasma activation conditions are investigated. It is shown that the composition of the gels plays the key role in determining their biochemical functions after the plasma activation. The antimicrobial performance of AVC is much better than that of PAW and the other two hydrogels, along with the excellent stability to maintain the antimicrobial activity for more than 14 days. The revealed mechanism of the antibacterial ability of the PAH identifies the unique combination of short‐lived species (1O2, ∙OH, ONOO− and O2−) stored in hydrogels. Overall, this study demonstrates the efficacy and reveals the mechanisms of the PAH as an effective and long‐term disinfectant capable of delivering and preserving antibacterial chemistries for biomedical applications. [ABSTRACT FROM AUTHOR]

Interactions of cold atmospheric‐pressure plasma jets (APPJs) and water are important for water purification, chemical synthesis, medicine, and biotechnology. However, the reactivity and bactericidal effects of water activated with jets of different ionized gases remain unclear, especially in the commonly used helium (He)‐ and argon (Ar)‐APPJ systems. Here, He and Ar are used as working gases to produce APPJ for comparing the plasma‐induced aqueous reactive species and bacteria inactivation effects in solutions. Experimental results indicate that the Ar plasma jet shows a quicker propagation velocity and higher concentrations of gaseous reactive species, and the gas and electron temperature are different for the He and Ar plasma. Moreover, the higher concentration of aqueous reactive species, such as ∙OH, ∙O2−/ONOOH, H2O2, NO2−, and NO3−, and better bacterial inactivation effects are achieved by the Ar plasma treatment. Water deformation induced from plasma water is found as the reason for the different reactivity and bactericidal effects. Further validation experiments using a film with different pore diameters confirm that the molecular weight of the working gas influences the shape and stability of the cavity induced by the gas flow in the plasma jet, and plays a vital role in the production of aqueous reactive species with variable concentrations. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide solutions are often utilized in logistics sterilization by misting, although their sterilizing capacity is diminished. To meet the high‐efficient and long‐term sterilization requirements of logistics, the reactivity and bactericidal efficiency are improved with plasma‐activated H2O2 solutions mist (PAHM). PAHM promotes an approximately double increase in the concentration of reactive nitrogen species, four times increase in the O3 concentration, and 36.2 times increase in H2O2 compared with water mist activation. Escherichia coli and Staphylococcus aureus are selected as the model microorganisms to evaluate the bactericidal activity. Results show that PAHM can reduce the numbers of both bacteria by two orders of magnitude after 3 min of treatment, similar to inactivated H2O2 for 10 min of treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • A transient spark gas–liquid discharge combined with TiO 2 was employed for the degradation of tetracycline in water. • A degradation rate of 90.2% was achieved by plamsa-TiO 2 system for 10 min treatment. • The catalyst TiO 2 exhibits a high efficiency at a lower pulse voltage. • Possible pathways of tetracycline degradation were deduced based on the analysis of intermediate by LC/MS. • The treated solution was proved to be harmless for the seed germination and plant growth. Water pollution driven by the increasing antibiotic abuse leads to serious ecological impacts and risks to human health. Non-thermal plasma, a sustainable advanced oxidation process, is considered as a promising approach for antibiotic degradation. In this study, a transient spark gas–liquid discharge was developed for the degradation of tetracycline in water and coupled with a photocatalyst (TiO 2) to further improve the degradation efficiency. Results show that the discharge was accompanied by intense UV light of up to 28 μW/cm2. The tetracycline degradation performance was strongly dependent on the pulse voltage, working gas, initial concentrations of tetracycline and the catalyst addition. The best degradation performance was achieved in the plasma-TiO 2 system with a degradation rate of 90.2% after 10 min treatment. The catalyst exhibits a high efficiency at lower pulse voltages, with the synergetic intensity of plasma and TiO 2 showing a decreasing trend with increasing pulse voltage. Radical quenching experiments suggest that hydroxyl radical (∙OH) plays a key role in the tetracycline degradation process. A pathway for tetracycline degradation by the plasma-TiO 2 process is deduced according to the analysis of the degradation intermediates. Further, seed germination and plant growth tests for the treated water demonstrated the feasibility of discharging the treated water to irrigate agricultural crops. [ABSTRACT FROM AUTHOR]

• New plasma-enhanced electrolytic oxidizing water sterilization method. • Decoupling anodic and cathodic reactions using an ion-exchange membrane. • Effective control of free chlorine and other reactive species by the plasma polarity. • Green, efficient, and stable plasma-electrified multipurpose water treatment approach. Pathogenic microorganisms pose a global threat to public health and environment. Common antibacterial chemicals produce toxic residues, inevitably harming the environment. Electrolyzed oxidizing water (EOW), a promising environment-friendly alternative disinfectant, still lacks effective production processes, sufficient bactericidal efficacy and stability, while the enabling physico-chemical mechanisms remain unclear. Here, we report, for the first time, an effective hybrid plasma electrochemical EOW production process and reveal the mechanisms by combining nonthermal plasmas and a two-chamber electrochemical cell separated by a cation exchange membrane (CEM) for decoupling the chemical reactions during the plasma treatment of water. Experimental results demonstrate that combined chlorine (chloramine) was the main chlorine product in the plasma-enhanced EOW (P-EOW) without a membrane, owing to the consumption of free chlorine (Cl 2 , HOCl, ClO−) by plasma-generated reactive nitrogen species. With a CEM in the plasma electrolysis system and through controlling the plasma discharge polarity, the production of free chlorine and other reactive species can be selectively controlled, with the highest concentration of free chlorine obtained in the negative plasma-enhanced EOW (NP-EOW). According to the transportation of cations by the CEM, the high concentrations of free chlorine may be attributed to the higher consuptions of H+ in cathode cell of negative plasma. The study of antibacterial ability of EOW produced under different conditions revealed that Staphylococcus aureus cells were best inactivated by the NP-EOW with CEM, which is mainly attributed to the higher concentration of free chlorine. This study demonstrates the feasibility of plasma-enhanced microbial electrolytic disinfection and offers new insights into the fundamental aspects of P-EOW chemistries for the future development of sustainable, efficient, and cost-effective multipurpose sustainable chemical technologies for water research and treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

Plasma-activated water (PAW) is considered to be an effective anticancer agent due to the diverse aqueous reactive oxygen and nitrogen species (RONS: ROS and RNS), but the drawback of low dose and short duration of RONS in acidified PAW limits their clinical application. Herein, this Letter presents an innovative therapeutic avenue for cancer treatment with highly-effective alkaline PAW prepared by air surface plasma. This anticancer alkaline formulation is comprised of a rich mixture of highly chemical RONS and exhibited a prolonged half-life compared to acidified PAW. The H2O2, NO2−, and ONOO−/O2− concentrations in the alkaline PAW can reach up to 18-, 16-, and 14-fold higher than that in acidic PAW, and the half-life of these species was extended over 8-, 10-, and 26-fold, respectively. The synergistic potent redox action between these RONS with alkaline pH was shown to be more potent than acidic PAW for cancer cell inhibition in vitro. Furthermore, the alkaline PAW injection treatment also significantly inhibited tumor growth in tumor-bearing mice. The possible reasons are that the alkaline PAW would disturb the acid extracellular milieu leading to the inhibition of tumor growth and progression; moreover, the efficient and durable RONS with alkaline pH could induce significant cell apoptosis by altering cell biomolecules and participating apoptosis-related signaling pathways. These findings offer promising applications for developing a strategy with real potential for tumor treatment in clinical applications. [ABSTRACT FROM AUTHOR]

In this study, a microbubble‐enabled plasma reactor driven by a nanosecond‐pulsed generator was developed to provide an effective means for transferring highly reactive plasma species into liquids for plasma‐activated water (PAW) production. The physicochemical characteristics of PAW at different temperatures were evaluated, and the corresponding antimicrobial effects of PAW against Escherichia coli cells were investigated. Results show that the microbubble‐enabled PAW at a lower temperature (10°C) had the highest antimicrobial activity, resulting in a 2.43 ± 1.02‐log10 reduction of E. coli in PAW. The excellent energy efficiency of the total reactive oxygen and nitrogen species production in PAW is 10.37 g kW−1 h−1. Overall, this study provides much‐needed insights into the microbubble‐enabled plasma chemistries for optimizing the biochemical activity of PAW. [ABSTRACT FROM AUTHOR]

Aims: This study aimed to compare the efficacy of plasma‐activated water (PAW) generated by two novel plasma reactors against pathogenic foodborne illness organisms. Methods and results: The antimicrobial efficacy of PAW produced by a bubble spark discharge (BSD) reactor and a dielectric barrier discharge‐diffuser (DBDD) reactor operating at atmospheric conditions with air, multiple discharge frequencies and Milli‐Q and tap water, was investigated with model organisms Listeria innocua and Escherichia coli in situ. Optimal conditions were subsequently employed for pathogenic bacteria Listeria monocytogenes, E. coli and Salmonella enterica. DBDD‐PAW reduced more than 6‐log of bacteria within 1 min. The BSD‐PAW, while attaining high log reduction, was less effective. Analysis of physicochemical properties revealed that BSD‐PAW had a greater variety of reactive species than DBDD‐PAW. Scavenger assays designed to specifically sequester reactive species demonstrated a critical role of superoxide, particularly in DBDD‐PAW. Conclusions: DBDD‐PAW demonstrated rapid antimicrobial activity against pathogenic bacteria, with superoxide the critical reactive species. Significance and impact of study: This study demonstrates the potential of DBDD‐PAW produced using tap water and air as a feasible and cost‐effective option for antimicrobial applications, including food safety. [ABSTRACT FROM AUTHOR]

Considering the increasing demand for fertilizers to support the global food supply, as well as the high-energy consumption and environmental concerns caused by industrial nitrogen fixation (i.e., Haber–Bosch process), there is a critical need to develop and integrate more sustainable, green-chemistry-based processes of nitrogen fixation. As a prominently electrified Power-to-X (where X stands for chemicals, fuels, and other high-value products) approach, non-thermal plasmas generated by the spark and gliding arc discharges are highly promising to meet the required criteria, especially when the power and the electrified chemical reactions are precisely dosed and timed using nanosecond repetitively pulsed plasmas. However, the underlying mechanism for NOx formation in plasmas is a stumbling block for further green chemistry process developments. Here, a nanosecond pulsed spark discharge based on a plate-to-plate configuration was developed for sustainable nitrogen fixation at ambient conditions. Outstanding energy efficiency of 4–11 g kW h−1 and a concentration of 960–10 900 ppm for NOx formation were obtained with the varied airflow rates ranging from 40 to 340 mL min−1. Using the optical emission spectroscopy and the chemical kinetics model, we found that the key intermediate species involved in NOx reaction pathways strongly depend on the plasma parameters and species residence time in spark discharges. It is revealed that more than 50% of the generated NO originate from the chain reactions of O and N radicals with vibrationally excited N2 and O2 molecules (O + N2(υ) → NO + N and N + O2(υ) → NO + O). Most NO2 molecules are formed by further oxidation of NO species (NO + O → NO2). The presence of O and N spectral lines at the post-discharge stage further confirmed the important role of free-radical-chain reactions. These results provide new insights into sustainable and decentralized NOx production, and deeper understanding of the plasma-based green chemistry will guide the optimization and practical applications of the plasma-based power-to-chemical nitrogen fixation. [ABSTRACT FROM AUTHOR]

[Display omitted] • New heavy oil processing approach through liquid-phase methane bubble discharge. • A competitive mechanism for radical hydrogenation and recombination is proposed. • High H density in CH 4 plasma contributes to the hydrogenation of aromatic rings. • The H density can be tuned by changing the bubble properties. Hydrogenation, an alternative to conventional cracking, is poised to revolutionize heavy oil upgrading by raising the hydrogen-to-carbon ratio at lower process pressures and temperatures. The emerging low-temperature plasma-enabled hydrogenation is an effective, fast, and environment-friendly process; however, the conversion rate and energy efficiency are still insufficient. To address these limitations, here we propose an innovative bubble-assisted methane plasma-liquid process for heavy oil processing (using ethylbenzene as a model compound) and offer new insights into radical-assisted hydrogenation. Results from the plasma kinetics modeling and density functional theory calculations indicate that ·H and ·CH 3 radicals generated by CH 4 plasma are two main drivers for ethylbenzene hydrogenation, and their chemical reaction rates with ethylbenzene molecules strongly depend on their spatial distribution in bubbles, which further govern the reaction direction towards ethylbenzene hydrogenation or free radical recombination. Moreover, it is found that by controlling the bubble numbers and plasma parameters, the H density can increase by an order of magnitude from 1.4 × 1020 to 3.88 × 1021 m−3, while the number of hydrogenated aromatic rings increases by ∼ 58%, which further confirms the excellences of the proposed plasma-bubble technology in chemical regulation and feasible processing. In addition, the feasibility of the plasma-enabled hydrogenation has been verified by the experiment, which highlighted the competition between the radical recombination and radical-aromatic ring interactions. Overall, the revealed interaction mechanisms between the plasma-generated radicals and ethylbenzene provide new insights and guiding principles for the future upgrading of heavy oils and other industrial hydrocarbon products. [ABSTRACT FROM AUTHOR]

Enhancing virus multiplication could assist in the rapid production of vaccines against viral diseases. Cold atmospheric plasma (CAP), a physical approach relying on reactive oxygen species to achieve the desirable cellular outcome, was shown to be effective in enhancing virus propagation, where bovine rhinotrachieitis virus and Madin-Darby Bovine Kidney cells were used as the modeling virus and cell line, respectively. CAP was shown to create synergies with virus infection in arresting host cells at the G2/M stage, decreasing cell membrane potential, increasing intracellular calcium level, and inducing selective autophagy. In addition, CAP was demonstrated to suppress virus-triggered immunogenic signaling as evaluated by IRF7 expression. We presented evidences on CAP-triggered maximization of host resources toward virus multiplication that is advantageous for viral vaccine production, and opened a novel regime for applying CAP in the sector of medical care and health. [ABSTRACT FROM AUTHOR]

Peroxynitrite is an important chemical in the human immune system, which has high biocidal activity and can resist the invasion of pathogens. Currently, in vitro generation of peroxynitrite faces major technological challenges, especially for gas‐phase production, which requires low‐pressure conditions. Here, we report the method of how to generate gas‐phase peroxynitrite at atmospheric pressure using dielectric barrier discharge. Results show that the peroxynitrite concentration positively correlates with energy density. Moreover, Penicillium digitatum, a common fungus contaminant greatly affecting food and fruit preservation, was used as a microbial pathogen model to confirm the biocidal effects of ozone‐free nitrogen oxides under different discharge conditions. The germination inhibition efficiency of P. digitatum is highly likely attributed to the synergistic effect of gaseous peroxynitrite and NO. [ABSTRACT FROM AUTHOR]

• Electrocatalytic CO 2 reduction to formate over mesoporous indium nanocrystals was carried out. • A facile solution method was designed for mesoporous indium (mp -In) synthesis. • The mp -In consisted of nanobelts with a high surface area and active sites for CO 2 RR. • A high formate selectivity with an FE of >90% was achieved over a broad potential window. • The current density was maintained at 20 mA cm−2 after 24 h of electrocatalytic CO 2 RR. Selective electrocatalytic reduction of CO 2 to formate has received increasing interest for CO 2 conversion and utilization. Yet, the CO 2 reduction process still faces major challenges, partly due to the lack of cost-effective, highly active, selective and stable electrocatalysts. Here, we report a mesoporous indium (mp -In) electrocatalyst composed of nanobelts synthesized via a simple solution-based approach for selective CO 2 reduction to formate. The mp -In nanocrystals provide enlarged surface areas, abundant surface active sites and edge/low-coordinated sites. Such advantages afford the mp -In with an outstanding electrocatalytic performance for the CO 2 -to-formate conversion. A high formate selectivity, with a Faradaic efficiency (FE) of >90% was achieved over a potential of −0.95 V to −1.1 V (vs V RHE). The mp -In catalyst showed excellent durability, reflected by the stable formate selectivity and current density over a 24 h reaction period. Density functional theory (DFT) calculations reveal that the stabilization of the intermediate OCHO* on the In-plane surfaces is energetically feasible, further elucidating the origin of its enhanced CO 2 -to-formate activity and selectivity. This work may offer valuable insights for the facile fabrication of porous hierarchical nanostructures for electrocatalytic and selective reduction of CO 2. [ABSTRACT FROM AUTHOR]

Plasma-activated water (PAW) represents a promising green antibacterial agent for biomedical and agricultural applications. In this study, a novel AC multi-needle-to-water discharge device was developed to investigate the effects of gas flow on the generation and chemical composition of PAW. It is shown that the concentrations of and N(III) (and) in the PAW both increased with an extension of the plasma-processing time and a reduction of the gas-flow rate. The absorption of gas-phase products carried by the gas flow from the discharge chamber was found to be beneficial for the generation of both and N(III) in the PAW at a gas flow rate of 20–60 L h−1, yet their concentrations were still lower than those without any feeding gas. As opposed to or N(III), the concentration in the plasma-activated phosphate buffer solution (PAPBS) increased under stronger gas flows and was almost unaffected by absorption in PAPBS. The pH value of PAW increased at higher gas flow rates. A comparison of the N(III) in PAW and PAPBS reflects the effects of the reactions of and in the two different working liquids. To quantify the effects of gas flow on the discharge characteristics, gas temperatures were calculated from the optical emission spectra and were proven to be flow-independent near the discharge channel. Fourier transform infrared (FTIR) measurements of the gaseous products during the discharge, and further analysis of possible reaction pathways indicated that by controlling the gas flow in the multi-needle-to-water discharge system, the concentration of long-lived species in PAW could be tuned, which might favor the generation of These findings contribute to a better understanding of effective electric discharge-related mechanisms for enhancing the biochemical and chemical activities of PAW. [ABSTRACT FROM AUTHOR]