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The Splendidus clade is the largest clade in Vibrionaceae, and its members are often related to mortality of marine animals with huge economic losses. The molecular bases of their pathogenicity and virulence, however, remain largely unknown. In particular, the complete genome sequences of the Splendidus clade species are rarely registered, which is one of the obstacles to predict core and/or unique genes responsible for their adaptation and pathogenicity, and to perform a fine scale meta-transcriptome during bacterial infection to their hosts. In this study, we obtained the complete genomes of all type strains in the Splendidus clade and revealed that (1) different genome sizes (4.4-5.9 Mb) with V. lentus the biggest and most of them had several big plasmids, likely because of the different features on mobilome elements; (2) the Splendidus clade consists of 19 species except V. cortegadensis, and 3 sub-clades (SC) were defined with the 15 most closely related members as SC1; (3) different carbohydrate degradation preferences may be the result of environmental adaptation; and (4) a broad prediction of virulence factors (VFs) revealed core and species unique VF genes.

The Hyf-type formate hydrogen lyase (FHL) complex was first proposed based on sequence comparisons in Escherichia coli in 1997 (Andrews et al. in Microbiology 143:3633-3647, 1997). The hydrogenase in the Hyf-type FHL was estimated to be a proton-translocating energy-conserving [NiFe]-hydrogenase. Although the structure of FHL is similar to that of complex I, silent gene expression in E. coli has caused delays in unveiling the genetic and biochemical features of the FHL. The entire set of genes required for Hyf-type FHL synthesis has also been found in the genome sequences of Vibrio tritonius in 2015 (Matsumura et al. in Int J Hydrog Energy 40:9137-9146, 2015), which produces more hydrogen (H

Streamer breakdown of atmospheric air with non-uniform dc electric field in a needle-to-plate electrode configuration is studied using a semi-analytic model and experimental measurements. A high voltage (either positive or negative) is applied to a hollow needle with 0.51 mm outer diameter and 0.25 mm inner diameter separated from a planar ground electrode by a gap distance of 0.1–1.4 cm. Breakdown voltages are recorded for both positive and negative discharge polarities. Empirical relations between the critical avalanche size for streamer breakdown and the gap distance are proposed. Using these empirical relations, a semi-analytic model based on Meek’s criterion for streamer breakdown is developed to accurately predict the measured breakdown voltages. It is found that for 380{\text{ Torr }}\;{\text{cm}}$?> p d > 380 Torr cm (or d $?> > 0.5 cm at one atmosphere) streamer breakdown of ambient air occurs at a lower applied voltage for a positively biased needle compared to that with a negatively biased needle, referred as the polarity effect. For p d < 380 Torr cm breakdown is attained at a lower applied voltage with a negatively biased needle compared to that with a positively biased needle, and breakdown mode transits from the polarity effect to the so called inverted polarity effect.

Plasma, the fourth and most pervasive state of matter in the visible universe, is a fascinating medium that is connected to the beginning of our universe itself. Man-made plasmas are at the core of many technological advances that include the fabrication of semiconductor devices, which enabled the modern computer and communication revolutions. The introduction of low temperature, atmospheric pressure plasmas to the biomedical field has ushered a new revolution in the healthcare arena that promises to introduce plasma-based therapies to combat some thorny and long-standing medical challenges. This article presents an overview of where research is at today and discusses innovative concepts and approaches to overcome present challenges and take the field to the next level. It is written by a team of experts who took an in-depth look at the various applications of plasma in hygiene, decontamination, and medicine, made critical analysis, and proposed ideas and concepts that should help the research community focus their efforts on clear and practical steps necessary to keep the field advancing for decades to come.

Currently, over 190 species in family Vibrionaceae, including not-yet-cultured taxa, have been described and classified into over nine genera, in which the number of species has doubled compared to the previous vibrio evolutionary update (Vibrio Clade 2.0) (Sawabe et al. 2014). In this study, "Vibrio Clade 3.0," the second update of the molecular phylogenetic analysis was performed based on nucleotide sequences of eight housekeeping genes (8-HKGs) retrieved from genome sequences, including 22 newly determined genomes. A total of 51 distinct clades were observed, of which 21 clades are newly described. We further evaluated the delineation powers of the clade classification based on nucleotide sequences of 34 single-copy genes and 11 ribosomal protein genes (11-RPGs) retrieved from core-genome sequences; however, the delineation power of 8-HKGs is still high and that gene set can be reliably used for the classification and identification of Vibrionaceae. Furthermore, the 11-RPGs set proved to be useful in identifying uncultured species among metagenome-assembled genome (MAG) and/or single-cell genome-assembled genome (SAG) pools. This study expands the awareness of the diversity and evolutionary history of the family Vibrionaceae and accelerates the taxonomic applications in classifying as not-yet-cultured taxa among MAGs and SAGs.

Nanosecond Pulsed Electric Fields (nsPEF) have the potential to treat a variety of cancer types including melanoma, pancreatic and lung squamous cancers. Recent studies show that nsPEF-based cancer therapy may be improved further with the assistance of moderate heating of the target. A feedback-looped heating system, utilizing a 980-nm fiber optic laser, was integrated into nsPEF electrodes for tumor ablation. The laser beam profile was determined to be Gaussian using a knife-edge technique. Thermal properties of the biological target were evaluated based on the treatment area, penetration depth and thermal distribution due to laser irradiation with or without nsPEF. Synergistic effects between nsPEF and the moderately elevated temperature at the target was observed, resulting in enhanced overall survival tumor regression up to 50% in the treatment of lung squamous cell cancer in mice.

Nonthermal atmospheric-pressure plasmas produce reactive plasma species including charged particles and reactive oxygen and nitrogen species, which are known to induce oxidative stress in living cells in liquid or tissue. In the meantime, pulsed electric fields have been widely used in reversible or irreversible electropermeabilization for either the delivery of plasmid DNA or inactivation of cancer cells. This work discusses the synergistic effects of nanosecond pulsed plasma jets and pulsed electric field on inactivation of pancreatic cancer cells in vitro and enhancement of plasmid DNA delivery to guinea pig skin in vivo . Higher inactivation rates of the cancer cells in suspension were obtained with combined treatment of 300-ns 50-kV/cm pulsed electric field and a 1-min exposure of a nanosecond pulsed, 250- $\mu \text{m}$ plasma jet. Increased efficiency of gene electrotransfer to skin was also observed after a 3-min treatment of a nanosecond pulsed, 1-mm plasma jet. Application of the plasma alone at the same dosage did not have significant effect on gene delivery. These findings signify the dosage-dependent cell response to both the electric fields and plasma. Importantly, the use of cold plasma to increase the sensitization of the biological cells in response to pulsed electric fields could be an effective approach to enhance the desired effects in electroporation-based applications.

Recently atmospheric pressure pulsed plasma jets (APNPJs) receive great interests due to their applications in various fields including medicine, food processing, bacteria inactivation etc. The generation of repeatable and stable APNPJs is hence important to their efficient applications. Here, we report an experimental study of the streamer initiation and breakdown (i.e streamer to spark transition) of an APNPJ using a ring-to-plate configuration. Using He as the working gas, ~0.26 mm diameter microplasma jet is generated in ambient air when a 0.504 mm outer diameter hollow needle was powered by 200 ns high voltage pulses. The pulsed voltage with respect to the interelectrode gap distance, ranging from 1mm to 11mm, was studied for various pulse width (160 ns – 5 μs), pulse repetition frequency (1 Hz – 10 kHz), and gas flow rates from 35 SCCM to 210 SCCM. While increasing the voltage increases the breakdown probability, longer pulse width and higher repetition rate result in lower hold-off voltage. Moreover, the differences in voltage and current waveforms as well as the UV-visible emissions for the streamer and spark are discussed.

Nonthermal atmospheric pressure plasma jets (APPJs) have shown effectiveness for the treatment of tumors in vitro. Similarly, nanosecond Pulsed Electric Field (nsPEF) has been investigated as anti-cancer therapy for its ability to permeabilize cells, disrupt electrolytes/ions balance and create oxidative injury. We report here the effects of a nanosecond pulsed APPJ and nsPEF employed alone or in combination on pancreatic cancer cells (Pan02) viability, proliferation and loss of integrity when cells were seeded as a monolayer. Driven by >8 kV, 200 ns pulses at 2 kHz, the APPJ completely inhibited cells proliferation after 1 min treatment when compared to control (p 0.05). Additionally, we confirmed the APPJ’s ability to disrupt cancer "stability" by provoking changes in transepithelial resistance, indicating an irreversible cell injury (p

Transient plasma ignition (TPI) has recently been attracting more attention due to the combination of its much larger volume ignition kernels and the generation of active radicals, which stabilizes the initial stage of the combustion by the enhancement of flame propagation rates compared with conventional spark ignition. In this study, TPI early flame propagation characteristics were investigated for near-atmospheric stoichiometric and lean mixtures of methane and air. Transient plasma was generated by applying nanosecond (pulse duration 10 – 12 ns), high-voltage (6 – 10 kV) pulses between two opposed pin-to-pin configurations with a gap distance of 3 mm residing within a custom-built constant volume combustion vessel. The delay to ignition and peak pressure as a function of voltage, air-fuel mixture rate (ϕ = 0.6 – 1.0), and pulse repetition frequency (PRF) of 1 – 10 kHz were evaluated. The early flame propagation and the discharge streamer phenomena were investigated via high-speed schlieren images as well as examining nanosecond pulses’ voltage-current waveform sequences. It is showed that a leaner mixture could reduce the ignition voltage range. The experiment results showed that higher PRF has potential advantages such as higher peak pressure, shorter ignition delay, faster flame propagation speed, smaller energy consumption, and leaner condition compared to conventional spark ignition.

Nonthermal atmospheric pressure plasma jet (APPJ) is a promising method for medical applications. In particular, it can induce temporary or permanent damage to tissue known as reversible electroporation (RE) and irreversible electroporation (IRE), respectively. RE enables the transfer of genes, drugs and proteins into cells. APPJ generates reactive oxygen and nitrogen species (RONS), which induces oxidative and nitrosative stress to cells. By generating low level of RONS, APPJ may change the sensitization of cells to RE and facilitate plasmid DNA delivery to cells and tissue. In this paper, we report pilot studies where air or helium plasma jets were applied to Guinea pigs for plasmid DNA delivery in vivo. Both devices were based on a dielectric barrier discharge (DBD) configuration. The air plasma jet was powered by a compact DC power supply, while the He plasma jet was driven by 200 ns, 8 kV pulses at 1 kHz. Plasmid encoding luciferase was delivered with each device. Bioluminescence was measured using an IVIS in vivo imager to evaluate expression levels achieved using the different delivery methods including plasma alone and the combination with pulsed electric fields (electroporation). The power consumptions were determined based on voltage and current measurements. RONS production by different plasma jets were evaluated.

Meeks’ criterion established a relationship between the fields around space charges in an electron avalanche and enabled prediction of the breakdown voltage across a gap given its distance and surrounding gas pressure. This criterion is reevaluated in this study for atmospheric pressure with a non-uniform electric field distribution where voltage up to 30 kV is applied to a ring-to-plate electrode configuration. The ring electrode is made of a stainless-steel needle with an inner diameter of 0.25 mm and an outer diameter of 0.51 mm, and is vertically placed above a copper grounding plate for various gap distances ranging from 1 to 14 mm. The breakdown voltage vs. gap distance and the V-I characteristics are obtained for both cathode-directed and anode-directed streamer discharges. The experimental results are found to be in good agreement with analytical predictions based on Meek’s criteria for self-propagating streamer accounting for a non-uniform electric field distribution across the gap. The results are also compared with Paschen’s law. Emergent behavior such as the negative polarity producing breakdown at progressively higher voltage than the positive polarity at gap distances greater than 6mm is discussed. This analysis concludes that Meeks’ criteria held throughout our results, overall, and offers suggestions for further refinements to related models and experiments.

Efficient gene delivery and expression in the skin can be a promising minimally invasive technique for therapeutic clinical applications for immunotherapy, vaccinations, wound healing, cancer, and peripheral artery disease. One of the challenges for efficient gene electrotransfer (GET) to skin in vivo is confinement of expression to the epithelium. Another challenge involves tissue damage. Optimizing gene expression profiles, while minimizing tissue damage are necessary for therapeutic applications. Previously, we established that heating pretreatment to 43 °C enhances GET in vitro. We observed a similar trend in vivo, with an IR-pretreatment for skin heating prior to GET. Currently, we tested a range of GET conditions in vivo in guinea pigs with and without preheating the skin to ~43 °C. IR-laser heating and conduction heating were tested in conjunction with GET. In vivo electrotransfer to the skin by moderately elevating tissue temperature can lead to enhanced gene expression, as well as achieve gene transfer in epidermal, dermal, hypodermal and muscle tissue layers.

Nanosecond pulsed electric field (nsPEF) causes the permeabilization of the cell membrane and has been used to non-thermally treat cancerous tissues. As increased permeabilization in membranes were reported to be accompanied by impedance changes, the ablation effect of nsPEF on tissues can be monitored via the changes in tissue conductivity. In this study, effects of nsPEF on biological tissues were evaluated by determining the conductivities of potato and 4 T1-luc breast tumor tissues ex vivo from a murine model subjected to multiple 100-ns, 1–10 kV pulses. Using a four-needle electrode system with a calibrated electrode constant of 1.1 ± 0.1 cm, the conductivities of tissues was determined from both the network-analyzer measurement, before and after treatment, and voltage-current measurement in real-time. The conductivity of the potato tissue was measured for a frequency range of 0.1–3 MHz, and it increased with increasing pulse number and voltage amplitude. The conductivity of the tumor tissue was also observed to increase with pulse number and pulse voltage over a similar frequency range. In addition, the linear correlation between the ablation area in a treated potato tissue and the conductivity change in the tissue suggests that conductivity analysis of biological tissue under treatment could be a fast and sensitive approach to evaluate the effectiveness of a nsPEF treatment.

Bipolar cancellation refers to a phenomenon when applying a second electric pulse reduces (“cancels”) cell membrane damage by a preceding electric pulse of the opposite polarity. Bipolar cancellation is a reason why bipolar nanosecond electric pulses (nsEP) cause weaker electroporation than just a single unipolar phase of the same pulse. This study was undertaken to explore the dependence of bipolar cancellation on nsEP parameters, with emphasis on the amplitude ratio of two opposite polarity phases of a bipolar pulse. Individual cells (CHO, U937, or adult mouse ventricular cardiomyocytes (VCM)) were exposed to either uni- or bipolar trapezoidal nsEP, or to nanosecond electric field oscillations (NEFO). The membrane injury was evaluated by time-lapse confocal imaging of the uptake of propidium (Pr) or YO-PRO-1 (YP) dyes and by phosphatidylserine (PS) externalization. Within studied limits, bipolar cancellation showed little or no dependence on the electric field intensity, pulse repetition rate, chosen endpoint, or cell type. However, cancellation could increase for larger pulse numbers and/or for longer pulses. The sole most critical parameter which determines bipolar cancellation was the phase ratio: maximum cancellation was observed with the 2(nd) phase of about 50% of the first one, whereas a larger 2(nd) phase could add a damaging effect of its own. “Swapping” the two phases, i.e., delivering the smaller phase before the larger one, reduced or eliminated cancellation. These findings are discussed in the context of hypothetical mechanisms of bipolar cancellation and electroporation by nsEP.

• We investigate the synthesis of Mn2Zn0.25Ni0.75O4 (MZN) thin films by radio frequency (RF) sputtering method at different sputtering powers. The variation of the film morphology, the crystalline structure, the cationic distributions and the optical properties are reported and explained by the variation of the film growth rate. Scanning electron microscopy results indicate that a too fast growth rate of the film results in dense surface defects or the degradation of the film crystallinity. X-ray photoelectron spectroscopy analysis suggests that oxygen defects are almost inevitable in such thin films deposited by RF sputtering. At a moderate (120 W) sputtering power the Mn2+ content increases 10–20% and the Mn4+ content is accordingly reduced. The detailed cationic configuration is proposed, where Zn2+ ions occupy both the tetrahedral site and the octahedral site. Raman and spectroscopic results allows asserting the relation between Mn valence states and the sputtering power.

A single needle-electrode helium microplasma jet powered by 5- or 164-ns 8-kV pulses at 500 Hz is investigated to elucidate the impact of nanosecond pulse rising rate and pulse duration on emission behaviors of plasmas. For the 5-ns pulsed plasma, the energy per pulse was measured to be 83 $\mu \text{J}$ , and it is 1.3 times of the 164-ns pulsed plasma. Time-integrated, spatially resolved emissions revealed that the shorter pulsed plasma generated higher production of excited $N_{2}^{+}$ (by a factor of 1.3) but less excited $N_{2}$ , He, O, and OH productions. In addition, all of these species maintained their maximal emissions near the needle nozzle, implying the importance of direct electron impact on generation of these excited species. Temporally resolved emissions showed that comparable or more excited species were produced by the 5-ns pulsed plasma for the first 100 ns, and the additional productions of excited species by the longer pulsed plasma occurred during the failing phase of the 164-ns voltage pulse. These findings suggested that rising and falling rates (≥ 1011 V/s) of a voltage pulse may not only play important roles in energy deposition during the plasma initiation but also influence the plasma chemistry that is associated with the production of excited species. The voltage pulse duration became important for the streamer development and charge transfer, which critically contributed to the total production of the reactive plasma species.

An array of nonthermal atmospheric-pressure helium plasma jets, in the shape of a brush, was generated in air when a rectangular, 0.1 mm thick anode was powered by 150 ns, 9.5 kV pulses at 2 kHz. With helium as the working gas at 1 slpm, each of the 11 jets of the plasma brush was 1 mm in width, and up to 1 cm long. The jets were spaced 4 mm apart, resulting in a lateral length of 51 mm. The bactericidal effect of the plasma brush was studied against Acinetobacter baumannii and Staphylococcus aureus inoculated on surfaces, including agar and laminate. The impact of humidity in the working gas, substrate type (agar versus laminate), and surface condition (wet versus dry) on the plasma-induced bactericidal effect was evaluated. In a humid discharge, bacterial inactivation was maximized at 0.6 log (75%), whereas adding water to the laminate surface before treatment yielded a 4 log (99.99%) reduction in bacterial viability. In addition, reactive plasma species, including excited O, NO, and OH were evaluated using optical emission spectroscopy for all plasma treatment conditions on laminate.

Series of negative temperature coefficient Mn–Co–Ni–O spinel oxide thin films were successfully prepared on thermally oxidized SiO2/Si (100) substrates by RF sputtering a Mn–Co–Ni metal alloy target with the sputtering gas of different Ar:O2 partial pressure ratios. The crystallinity of the spinel films was improved as O2 contents increased. The film conductivity was reduced. The minute variation in an optical absorption peak at around 1.7 eV by spectroscopic ellipsometry may be ascribed to the different charge transfer mechanism between Co2+ in tetragonal and Co3+ in octahedral or between O2− and Mn4+ in octahedral sites. Raman and XPS results provided further evidences.

Nanosecond pulsed non-thermal atmospheric-pressure plasmas are promising for numerous applications including air and water purification, ozone synthesis, surface sterilization, material processing, and biomedical care. However, the high cost of the nanosecond pulsed power sources has hindered adaptation of the plasma-based technologies for clinical and industrial use. This paper presents a low cost ( 10 kV, a 3 ns rise time (10 to 90 %), and a 10 ns pulse duration (full width at half maximum) at a pulse repetition rate of up to 500 Hz were achieved in the present study. It has been successfully tested to power three different plasma reactors to form pulsed corona discharges, dielectric barrier discharges, and sliding discharges. The energy efficiency of such a nanosecond pulsed sliding discharge system was assessed in the context of ozone synthesis using air or oxygen as the feed gas, and was found comparable to a previously reported non-thermal plasma system that used commercial high voltage pulsed power sources. This study demonstrated that this low-cost nanosecond pulsed power source can prove to be an energy efficient and simple supply to drive various non-thermal atmospheric-pressure plasma reactors for environmental, medical and other applications.

Non-thermal atmospheric-pressure plasma jets are of interest to various biomedical applications including bacterial inactivation, surface modification and sterilization, wound healing and tumor apoptosis. The electric field and charge near the bio-substrates were considered important agents influencing the plasma-induced biomedical effects due to the possible electroporation and chemical processes. This work investigated the charges and electric field in the bio-substrates with the plasma jet impinging on the substrate. Ultrapure water, PBS (phosphate buffered saline) solution and pig skin were used as the substrates. The plasma jet was based on a dielectric barrier discharge (DBD) configuration, powered by 180 ns, 6 kV pulses at 1 kHz and with helium flow of 985 sccm (standard cubic centimeters per minute). The charges delivered to the substrates are evaluated by jet current and compared. There is an optimal gap distance of 5mm for water and 10mm for PBS solution and pig skin. Pig skin consumes the most energy. The electrical field is evaluated by measuring the potential difference in water, which shows that there exists electric field remaining after plasma jet strikes on the water surface. Applying higher voltage can get higher electric field in water.

Combustion efficiency and rate of ignition were shown to be improved when fuel-air ignition was initiated with highly non-equilibrium plasmas generated by highvoltage, nanosecond pulses, also known as transient plasma ignition (TPI). In order to optimize the pulse power parameters for plasma ignition for combustion, detailed experimental investigations of the effect of risetime and pulse repetition frequency (PRF) were conducted for atmospheric pressure static methane/air ignitions. Plasmas driven by 10 ns, 12 kV pulses at a range of PRF from 1 kHz to 10kHz were generated for combustion ignition with a conventional spark plug electrode configuration. Experiments revealed that a different mode in the plasma was initiated when the fuel/air mixture was ignited. At constant pulse duration and PRF, this plasma occurred earlier for the faster rise time (e.g. 4 ns) compared to the longer one (e.g. 8 ns) [1]. In addition, faster PRF favored the earlier plasma mode change or earlier ignition. Importantly, the kinetics of reactive plasma species that were generated during the TPI and combustion were investigated using optical emission spectroscopy (OES). Filtered high speed imaging in combination with electrical measurements are to help understand the plasma rotational temperature related to combustion that is initiated with different pulse rise times and PRFs at a constant pulse width of 10 ns. Gas temperature of the repetitively pulsed plasma ignition for combustion is discussed by measuring the rotational temperature of the second positive systems of nitrogen N2 (C-B).

According to the adaptability of electronic equipment in complex electromagnetic environment, this paper establishes an analytical model based on the experimental samples collected, and completes the adaptability analysis of the electronic equipment to the complex electromagnetic environment. Firstly, the zero phase component analysis (ZCA) is used to process the experimental data to remove the data correlation. On this basis, the problem is regarded as unsupervised learning. The hierarchical clustering method is used to classify the electromagnetic environment, and the optimal adaptability of the equipment under different environmental classification is analyzed. And gives the range of the system parameters that can make the equipment achieve the best adaptability. The validity of the model is verified by simulation experiments.

Joint estimation of delay and angle in multipath environments is a key link in wireless positioning. A joint delay and angle estimation at low complexity based on propagator method of the extended subspace is presented. The propagator method is used to estimate the extended noise subspace of the received signal, and the parameters are automatically paired. The algorithm not only effectively reduces the computational complexity, but also accomplishes the high precision estimation when the number of paths exceeds the number of antennas. The validity and feasibility of the proposed algorithm are verified by simulation.

Transient plasma ignition (TPI) employs highly non-equilibrium plasmas driven by nanosecond high-voltage pulses for combustion ignition. The effects of rise time and pulse repetition frequency (PRF) on combustion ignition are evaluated when transient plasmas, powered by 10-ns, kilovolt pulses, are employed to initiate combustion of lean, stoichiometric, or rich methane-dry air mixtures at atmospheric pressure. It was found that the plasmas driven by high voltage pulses with a faster rise time and PRF between 6–10 kHz enhanced combustion with higher peak pressure and/or shorter ignition delay. A mode transition in the plasma, corresponding to the combustion initiation, was observed based on voltage and current waveforms of four consecutive pulsed plasmas driven by a pulse burst at kilohertz PRFs. Although benefits in combustion ignition from a shorter rise time and optimal PRF were observed for all three equivalence mixture ratios, the highest peak pressure and shortest ignition delay were associated with the stoichiometric mixtures. In addition, the gas temperature of the transient plasma was measured by determining the rotational temperature of the 2nd positive system of nitrogen to be ∼1000 K for the first pulse and increased up to 2000 K after the application of the 4th pulse in a four-pulse burst TPI.

Bacillus pumilus SWU7-1 was isolated from strontium ion (Sr(II))-uncontaminated soil, its biosorption potential was evaluated, and the effect of γ-ray radiation treatment on its biosorption was discussed. Domesticated under Sr(II) stress promoted the biosorption ability of B. pumilus to Sr(II), and the biosorption efficiency increased from 46.09% to 94.69%. At a lower initial concentration, the living bacteria had the ability to resist the biosorption of Sr(II). The optimal initial concentration range was 54–130 mg/L. The biosorption profile was better matched by Langmuir than Freundlich model, showing that the biosorption process of Sr(II) by the experimental strain was closer to the surface adsorption. According to Langmuir model, the maximum biosorption capacity of B. pumilus on Sr (II) was 299.4 mg/g. During the bacterial growth in the biosorption process, the changes in biosorption capacity and efficiency can be divided into two phases, and a pseudo-second-order model is followed in each phase. There was no significant difference in the biosorption efficiency of bacteria with different culture time after γ-ray radiation, and all of them were above 90%, which showed that B. pumilus had significant radiation resistance under experimental conditions. This study emphasized the potential application of B. pumilus in the treatment of radioactive Sr(II) pollution by biosorption.

Dosage control of reactive oxygen and nitrogen species (RONS) is critical to low-temperature plasma applications in cancer therapy. Production of RONS by atmospheric pressure, nonequilibrium plasmas in contact with liquid may be modulated via plasma conditions including plasma treatment time and pulse voltage and repetition frequency. In this study, a terephthalic acid-based probe was used to measure hydroxyl radicals [OH(aq)] in water exposed to plasma and to demonstrate that the OH(aq) concentration increases linearly with treatment time. Fluorometric measurements of hydrogen peroxide concentration in plasma-activated water show a linear relationship between the H2O2 production rate and the pulse repetition frequency of the plasma. In vitro plasma treatment of cancer cells shows that pancreatic (Pan02) and breast (4T1-Luc) cancer cells have different sensitivities to plasma exposure. The dependence of Pan02 cell viability on plasma treatment time or pulse voltage is nonlinear. The system described here for generation and delivery of reactive oxygen species from a nanosecond pulsed plasma jet represents a promising alternative approach to cancer therapy.

Effects of temperature on nitric oxide (NO) production and on byproduct nitrogen dioxide (NO2) and ozone (O3) in a non-equilibrium sliding discharge in atmospheric pressure air are described. Heating the electrodes/dielectric surfaces in contact with the discharge plasma from 20 °C to 420 °C caused an increase in energy per pulse by more than an order of magnitude. More importantly, heating to a few hundred degrees above room temperature caused the destruction of ozone (O3) and the reduction of nitrogen dioxide (NO2) but promoted NO formation. At 20 °C, 400–4500 ppm O3 with an energy cost of 2–4 MJ/mol, and 12–180 ppm NO2 with an energy cost of 75–140 MJ/mol were generated from dry air flowing at 1 lpm. At 220 °C, however, NO and NO2 were produced in about equal proportion while O3 was below detection limits. The efficiency of NO generation increased with an increase of temperature. At the maximum temperature used in this study, i.e., 420 °C, 160–1040 ppm NO was produced from dry air at an energy cost of 24–67 MJ/mol, with a NO/NO2 ratio of more than 4 and free of O3.

A Pancreatic cancer is a notorious malignant neoplasm with an extremely poor prognosis. Current standard of care is rarely effective against late-stage pancreatic cancer. In this study, we assessed nanopulse stimulation (NPS) as a local treatment for pancreatic cancer in a syngeneic mouse Pan02 pancreatic cancer model and characterized corresponding changes in the immune profile. A single NPS treatment either achieved complete tumor regression or prolonged overall survival in animals with partial tumor regression. While this is very encouraging, we also explored if this local ablation effect could also result in immune stimulation, as was observed when NPS led to the induction of immune-mediated protection from a second tumor challenge in orthotopic mouse breast and rat liver cancer models. In the Pan02 model, there were insufficient abscopal effects (1/10) and vaccine-like protective effects (1/15) suggesting that NPS-induced immune mechanisms in this model were limited. To evaluate this further, the immune landscape was analyzed. The numbers of both T regulatory cells (Tregs) and myeloid derived suppressor cells (MDSCs) in blood were significantly reduced, but memory (CD44+) T-cells were absent. Furthermore, the numbers of Tregs and MDSCs did not reduce in spleens compared to tumor-bearing mice. Very few T-cells, but large numbers of MDSCs were present in the NPS treated tumor microenvironment (TME). The number of dendritic cells in the TME was increased and multiple activation markers were upregulated following NPS treatment. Overall, NPS treatments used here are effective for pancreatic tumor ablation, but require further optimization for induction of immunity or the need to include effective combinational NPS therapeutic strategy for pancreatic cancer.

Plasma-produced reactive oxygen species (ROS), such as hydroxyl radicals (OH), have a wide variety of applications, including sterilization of surfaces, food processing and even optimization of plasma ignition efficiency for combustion. Generation of these species is heavily dependent on the pulse parameters, including pulse width, pulse rise time and the energy per pulse. It has been reported that the majority of OH is generated during the rising and falling time of the pulse [1]. When using longer pulse durations (>200-ns), these events can be seen as separate OH generation events. But when a much shorter pulse duration is used (~ 10-ns), these events happen so close together that they overlap, affecting the plasma chemistry and energy deposition [2]. It is currently unknown if the pulse rise time has an effect on the production of OH at shorter pulse durations. Using a single needle electrode, a helium plasma jet was generated in air using a 10-ns pulse width and a rise time of either 3-ns or 9-ns. The spatially and temporally resolved OH production by 10-ns pulse helium plasma jets in ambient air were measured using laser induced fluorescence. The effect of the pulse rise time on OH production is discussed.

Non-invasive laser diagnostics such as Thomson scattering and Two-Photon Absorption Laser Induced Fluorescence (TALIF) are powerful tools to measure electron properties and to probe the plasma chemistry with high spatial and temporal resolutions. Using laser Thomson scattering, the electron density and electron temperature of a 140-ns pulsed helium plasma jet were resolved in distributions of bell-shaped profiles with lower values in the center and higher at the outer edge of the 1-mm diameter helium flow column. Laser energy dependence studies were performed to validate the quantitative measurements. Absolute atomic oxygen measurements for the same plasma jet using TALIF, however, revealed a Gaussian-shaped distribution of the O-density. Dependence of the electron properties and atomic oxygen generation on the peak voltage of the applied nanosecond pulses and the oxygen concentration in helium are discussed.