Cold Plasma Jets

This study aimed to evaluate the effects of micron sized non-thermal atmospheric pressure plasma inside the animal body on breast cancer tumor. The μ-plasma jet consists of micron sized hollow tube in which pure helium gas is ionized by high voltage (4 kV) and high frequency (6 kHz). The efficiency of the plasma treatment in killing cancer cells was first investigated by cell viability measurements of treated 4T1 cells using flow cytometry and cell cycle analysis. For exploration of the in vivo effects of the plasma treatment, the BALB/c mice inoculated by 4T1 cell lines were exposed subcutaneously to plasma for 3 minutes. In addition, H&E staining, TUNEL and Western blotting assays were performed in order to observed the effects of the non-thermal plasma on the tumor cells. The results showed that the efficiency of the plasma in suppression of the tumor growth is comparable to that of a typical chemotherapy drug. Moreover, the results indicated that the plasma induces apoptosis in ...

This work presents the numerical simulation of the melting process of a particle injected in a plasma jet. The plasma process is nowadays applied to produce thin coatings on metal mechanical components with the aim of improving the surface resistance to different phenomena such as corrosion, temperature or wear. In this work we studied the heat transfer including phase-change of a bi-layer particle composed of a metallic iron core coated with ceramic alumina, inside a plasma jet. The model accounted for the environmental conditions along the particle path. The numerical simulation of this problem was performed via a temperature-based phase-change finite element formulation. The results obtained with this methodology satisfactorily described the melting process of the particle. Particularly, the results of the present work illustrate the phase change evolution in a bi-layer particle during its motion in the plasma jet. Moreover, the numerical trends agreed with those previously reported in the literature and computed with a finite volume enthalpy based formulation.

Arrays of atmospheric-pressure plasma jets are being considered as a means to increase the area being treated in surface modification and in plasma medicine in particular. A unique challenge of scaling plasma jet arrays is that individual plasma jets in an array tend to interact with each other, which can lead to quenching of some individual jets. To investigate these potential interactions, a computational study of one-, two-and three-tube arrays of micro-plasma jet arrays was performed. An atmospheric-pressure He/O 2 = 99.8/0.2 mixture was flowed through the tubes into humid room air. We found that the jets interact through electrostatic, hydrodynamic and photolytic means. The hydrodynamic interactions result from the merging of individual He channels emerging from individual tubes as air diffuses into the extended gas jets. Ionization waves (IWs) or plasma bullets, which form the jets on the boundaries of an array, encounter higher mole fractions of air earlier compared with the center jet and so are slower or are quenched earlier. The close proximity of the jets produces electrostatic repulsion, which affects the trajectories of the IWs. If the jets are close enough, photoionizing radiation from their neighbors is an additional form of interaction. These interactions are sensitive to the spacing of the jets.

In this study, a method for experimentally evaluating the plasma parameters in the Argon plasma jet system with varying rates of Argon gas flow from 1 to 5 L/min operating at constant voltage and normal atmospheric pressure. This study is based on optical emission spectroscopy (OES). Spectroscopic diagnostic method using the Boltzmann plot to calculate these parameters measured. Generally, the results show the value of Te ranged from 1.53 to 1.78 (eV) depending on the gas flow rates, electron density ranges from 2.63 to 3.12 Â 10 17 (cm À3). The plasma parameters such as (λ D , N D , and ω p) related to electron temperature and electron density was also measured. The plasma was produced at a different flow rate the impacts on Debye length, plasma frequency, and the number of particles on the surface of Debye, all of which rise with an increase in gas flow rate, are significantly influenced by an increase in gas flow rate on the plasma properties of the density and temperature of an electron.

Breast cancer exists in multiple subtypes some of which still lack a targeted and effective therapy. Cold atmospheric plasma (CAP) has been proposed as an emerging anti-cancer treatment modality. In this study, we investigated the effects of direct and indirect CAP treatment driven by the advantageous nanosecond pulsed discharge on breast cancer cells of different malignant phenotypes and estrogen receptor (ER) status, a major factor in the prognosis and therapeutic management of breast cancer. The main CAP reactive species in liquid (i.e. H2O2, NO2−/NO3−) and gas phase were determined as a function of plasma operational parameters (i.e. treatment time, pulse voltage and frequency), while pre-treatment with the ROS scavenger NAC revealed the impact of ROS in the treatment. CAP treatment induced intense phenotypic changes and apoptosis in both ER+ and ER- cells, which is associated with the mitochondrial pathway as evidenced by the increased Bax/Bcl-2 ratio and cleavage of PARP-1. In...

The application of cold plasma therapy for the treatment of cancer is one promising field of study. This therapy can target and kill cancer cells while sparing healthy cells. The reactive oxygen species (ROS) and reactive nitrogen species (RNS), produced during plasma treatment is responsible for the cancer cells death. The research on cold plasma therapy is underway and has the potential to enhance current cancer treatments. Breast, lung, and skin cancer have all been treated with excellent success with cold plasma treatment. Cold plasma therapy has been shown to have anti-inflammatory, anti-angiogenic, and immunomodulatory properties in addition to its capacity to target cancer cells specifically, which may further increase its therapeutic potential. Additionally, it has been demonstrated that the efficiency of cold plasma therapy combined with other cancer therapies like chemotherapy, radiation therapy, and immunotherapy enhance the overall success of cancer treatment. Despite th...

Guiera senegalensis (GS) reflects the reduced glucose exposure of erythrocytes over a preceding time frame proportional to erythrocyte survival. GS is thus an anti-diabetic function of the glucose-time curve, an educationally useful concept to aid teaching and clinical judgment. Sixty-one newly diagnosed patients with an average age of 48.2 years and weight of 64.9 kg have participated in the study. Participants were significantly different in their educational, socioeconomic levels, and most of them have no family history of diabetes. To evaluate the hypoglycemic effect of GS, the patients were divided into four groups (G1, G2, G3 and G4) and treated with four different doses of the aqueous extract of the herb ( 0.5, 1, 1.5 and 2 Oz of GS boiled for 10 minutes in 0.5-litre water). The experiment has lasted for five days for each group, and the blood glucose level of the patients was checked using GOD –POD method, at fasting (FBS) and following two hours after the breakfast (RBS). A...

Application of air plasma jet was studied for the materials of light industry (rubber, wood, fabrics). Regulation of temperature of remote plasma was used to apply high energy treatment on thermo-sensitive materials like denim fabric. Air plasma jet with adjusted plasma temperature permitted to realize effective colour fading of denim without heat damaging of denim fabric.

Plasma medicine is an innovative research field combining plasma physics, life science, and clinical medicine. It is mainly focused on the application cold atmospheric plasma (CAP) in therapeutic settings. Based on its ability to inactivate microorganisms but also to stimulate tissue regeneration, current medical applications are focused on the treatment of wounds and skin diseases. Since CAP is also able to inactivate cancer cells, its use in cancer therapy is expected to be the next field of clinical plasma application. Other promising applications are expected in oral medicine and ophthalmology. It is the current state of knowledge that biological CAP effects are mainly based on the action of reactive oxygen and nitrogen species supported by electrical fields and UV radiation. However, continuing basic research is not only essential to improve, optimize, and enlarge the spectrum of medical CAP applications and their safety, but it is also the basis for identification and definiti...

An atmospheric pressure plasma jet (APPJ) using medical-grade argon gas as the carrier gas was developed and used to investigate wound healing in small animals combined with Binahong (Anredera cordifolia) leaf extract treatment. The experiment was divided into 4 treatment groups, control (C), plasma jet (P), Binahong leaf extract (B), and Binahong leaf extract followed by plasma jet (PB). Plasma jet treatment for wounds was applied in different styles based on the treatment day. Both P and PB treatments were contact-style for days 0-4 (5-mm distance for 1-min duration) and noncontact style for days 5-13 (20 mm for 3 min). The total period of wound observation was 14 days. Histological evaluation using hematoxylin-eosin (HE) staining was performed on days 7, 11, and 14 to evaluate wound reepithelialization. Meanwhile, the number of neutrophil cells was counted using a hematology analyzer on days 11 and 14, and malondialdehyde (MDA) levels were examined on days 7 and 14. This research revealed that plasma jet successfully improved wound healing; on the other hand, plasma jet treatment preceded by Binahong leaf extract treatment tended to impede wound healing. It is hypothesized that Binahong may reduce plasma jet effectiveness in wound healing.

A multiphase Lattice Boltzmann (LB) scheme coupled with a level set interface capturing module is used for the simulation of multiphase flows, and in particular, rising bubbles under moderate and high density and viscosity ratios. We employ a consistent, robust discretization of the pressure forces which enables us to preserve stability and accuracy. The accuracy of the present scheme is shown to be competitive with that of the benchmark data from the finite element solutions in [3].

Plasma medicine is an innovative research field combining plasma physics, life science, and clinical medicine. It is mainly focused on the application cold atmospheric plasma (CAP) in therapeutic settings. Based on its ability to inactivate microorganisms but also to stimulate tissue regeneration, current medical applications are focused on the treatment of wounds and skin diseases. Since CAP is also able to inactivate cancer cells, its use in cancer therapy is expected to be the next field of clinical plasma application. Other promising applications are expected in oral medicine and ophthalmology. It is the current state of knowledge that biological CAP effects are mainly based on the action of reactive oxygen and nitrogen species supported by electrical fields and UV radiation. However, continuing basic research is not only essential to improve, optimize, and enlarge the spectrum of medical CAP applications and their safety, but it is also the basis for identification and definiti...

Low temperature plasmas that can be generated at atmospheric pressure and at temperatures below 40 • C have in the past couple of decades opened up a new frontier in plasma applications: biomedical applications. These plasma sources produce agents, such as reactive species (radicals and non-radicals), charged particles, photons, and electric fields, which have impactful biological effects. Investigators have been busy elucidating the physical and biochemical mechanisms whereby low temperature plasma affects biological cells on macroscopic and microscopic scales. A thorough understanding of these mechanisms is bound to lead to the development of novel plasma-based medical therapies. This mini review introduces the reader to this exciting multidisciplinary field of research.

Using a one-way coupled model of neutral gas flow and plasma dynamics we report a mechanism to explain the ring-shaped emission pattern that has been observed experimentally in plasma bullets at atmospheric pressure. We solve a fluid model with the local field approximation in one-dimensional cylindrical coordinates, corresponding to a cross-section of a plasma bullet. Pulselike uniform electric field is assumed to be applied perpendicular to the simulation domain. Time and spatially resolved spectroscopic measurements support the simulation results.

-L'Université de Limoges dans le cadre de la réhabilitation de ses locaux scientifiques s'est trouvé confrontée à la mise au rebut de biens patrimoniaux irremplaçables dans le contexte « post moderne » ou « post industriel » de notre société industrielle. C'est pourquoi une « Mission Patrimoine scientifique et culturel » a été créée en 2010 afin de sauvegarder le plus possible la mémoire du dernier demi-siècle. Pour des raisons que nous évoquons les plasmas et les arcs électriques ont eu une place importante à cette époque dans l'industrie occidentale et fortuitement particulièrement à Limoges 1.1. La Mission Patrimoine scientifique et culturel de l'Université de Limoges Elle a pour objet de constituer la mémoire de l'université (à l'exclusion des archives de l'administration). Elle se propose donc de :  Collecter et sensibiliser au patrimoine matériel et immatériel,  Sauvegarder et rechercher les moyens de sauvegarde  Valoriser et faire alliance avec des structures de valorisation. Le patrimoine proprement dit est matériel ou immatériel.  Matériel avec les instruments et appareils, les écrits, les documents des chercheurs, tiré-à-part, cahier de labo, images, sons, supports multimédia, etc.  Immatériel avec les pratiques, représentations, expressions, connaissances et savoir-faire, mémoire humaine (« souvenirs » à interroger), etc.

This article aims to address the issue of simulating plasma-jet by using an innovative computational approach namely the Lattice Boltzmann Method (LBM) from the point of view of extending the applications to simulating flows with temperature-dependent physical parameters. The work focuses on the phenomena occurring in plasma-jet that define the link between LBM lattice and physical lattice. High temperature dependence of the plasma parameters is considered. Argon characteristics fall into this category. This gas is one of the most ones used in plasma spraying. Complex thermal plasma jet phenomena and basis of classical methods in CFD (discretisation, stability condition, modeling…), in one side, and the simple scheme of the Boltzmann equation which is particularly adopted for simulating gases flows, in the other side, give us the possibility of taking out the dynamic and thermal characteristics of this complex flow. An important section on validation of this model includes details o...

This study aims to analyse axisymmetric turbulent argon plasma jet charged with particle/droplet stream and its impact characteristics during atmospheric spraying process. The governing partial differential equations are solved using a double population lattice Boltzmann (LB) numerical model (D2Q9eD2Q4) coupled LES turbulence model. The powder dynamics and heating were modeled using a Lagrangian plasmaeparticles interaction model. A validation of the developed LB model on argon plasma jet was done, leading to credible results and the focus was thus mainly made on the plasmaeparticle exchanges during the powder journey in argon plasma. The effects of injection conditions on the spray stream of molten particles and the particles impacting conditions (velocity, temperature, melting rate, …) are carried out for four selected operating parameters, i.e. particle diameter, injection velocity, injection position (along injector section) and the injection angle at the injector exit. It has been observed that the LB method is a powerful tool for investigating plasma jet flows. It was concluded through the tracking model of the micro-sized particles that the present LB-based results agree well with the FD-based results and that the spray stream depends strongly on the studied injections conditions. Besides, the splashing phenomenon is found to be a rule governing particle/droplet impact behaviors.

In the present study, we investigate a PSP using the Jets&Poudres soft. The plasma gas understanding is given to highlight the effects of gas mixtures proportions on diffusion parameters. An overview on the process complexities at main subsystems is given with focus on Argon plasma and optimal mixing; the powder acceleration and heat-up modeling are also presented. Under literature conditions and for HeAr -H 2 65-30-5% gas, it was found that the droplet's primary way is to coat. The used ternary mixture gives superior efficiency compared to the pure Argon which shows a prior way to rebound. Moreover, medium particles (d p E 45 mm) present the high deposited rate among the splashed mass, a 100% molten ratio is observed for the small powder and only particles of size below 40.3 mm have evaporated, particles of initial diameter between 40.3 and 49 mm are fully molten and all particles above 71.9 mm are fully solid. The coat formed by the deposited mass will transfer a large amount of heat to the substrate (9-58 MW/m 2). The crushed particle's rate is about 4% from the investigated number and the average fully molten particle's rate is about 72% and the rest of particles arrive in solid sate.

This study aims to investigate turbulent plasma flow over spheroidal particles using the lattice Boltzmann (LB) method. A double population model D2Q9-D2Q4 is employed to calculate the plasma velocity and temperature fields. Along with the calculation process a conversion procedure is made between the LB and the physical unit systems, so that thermo-physical properties variation is fully accounted for and the convergence is checked in physical space. The configuration domain and the boundary condition treatment are selected based on the most cited studies in order to illustrate a realistic situation. The jet morphology analysis gives credible results by comparison with commonly published works. A second Lagrangian model has been developed to investigate the plasma-particles exchange during its in-flight. The tracking of the μ-sized particles allows concluding that our results are in sufficient agreement with those of the Jets&Poudres code and that the LB method account well for plasma jet physics which affects directly the particles in-flights.

Structural bifurcation of microwave-sustained jet discharge at atmospheric gas pressure was found to produce a stable helium plasma jet, which may open the possibility of a new type of high-flux test plasma beam for plasmawall interactions in fusion devices. The fundamental discharge properties are presented including hysteresis characteristics, imaging of discharge emissive structure, and stable ignition parameter area.

and plasma, we developed a radio-frequency glow microdischarge along a miniature water flow that was surrounded by a coaxial helium gas flow in a quartz tube under atmospheric pressure. The de-ionized water was supplied through a nozzle electrode that had a counter needle electrode. The discharge developed at the edge of nozzle electrode, the triple point including gas, water, and metal. The stable microdischarges were obtained without the formation of water droplets. Glow to spark transition appeared at high input rf power. Thanks to the quartz tube, the discharges were not affected by ambient air including nitrogen and oxygen molecules. Optical emission spectroscopy was conducted to examine the effect of water flow on the discharges. OH and HeI lines with significant intensities were observed. The microplasma structure enhances the surface interaction between the glow discharge and the water flow, which assists physical and chemical reactions. This was verified by observing the emission of intense OH lines.

The study of the effects of operating parameters on cellular changes in plasma-cell interaction is an important research issue for successful biomedical application of atmospheric pressure plasmas. The control parameters of atmospheric pressure plasma jet include applied voltage, driving frequency, pulse duty ratio, gas flow rate and additive oxygen gas. The effects of these parameters on the plasma-cell interaction are investigated. A plasma jet is driven by pulsed dc voltage with low frequency and human bladder cancer cells (EJ) is employed as a living tissue. The plasma-cell interaction in EJ cells triggers typical apoptosis. Especially, helium plasma with additive oxygen gas was found to be effective in the apoptosis. Reactive oxygen species (ROS) which causes damage to cell membranes and leads to DNA fragmentation in cells is generated by plasma jet. It plays an important role in apoptosis induction. To identify the correlation between the apoptosis rate and the amount of ROS in plasma jet, staining assay analysis and the measurement of extracellular ROS are compared. The apoptotic changes in cell with plasma treatment are detected by fluorescence microscopy and flow cytometry. Fluorescence microscopy could be used by DAPI staining and TUNEL assay to confirm morphological changes and DNA fragmentation characteristics of cells undergoing apoptosis. Flow cytometry could be used by Annexin-V/PI staining to quantify the percentage of apoptotic cells present in a cell population. Also, the extracellular ROS was measured by optical emission spectroscopy (OES). A portion of EJ cells was observed to undergo apoptosis in plasma treatment clearly. The number of apoptotic cells increased with applied voltage, repetition frequency, gas flow rate, and additive oxygen gas, while they decreased with working media and pulse duty ratio. And the variation of apoptosis rates was similar to that of ROS intensities. The result indicated that the apoptosis rate correlated well with the level of extracellular ROS.

In this community white paper, we describe an approach to achieving fusion which employs a hybrid of elements from the traditional magnetic and inertial fusion concepts, called magneto-inertial fusion (MIF). The status of MIF research in North America at multiple institutions is summarized including recent progress, research opportunities, and future plans.

Dielectric-barrier-discharge (DBD) plasma jets provide viable state-of-the-art nonthermal processes for a wide range of nanomaterials including particle transport and deposition. We report the interaction of argon and helium plasma jets with the particle aerosol, produced by ns laser ablation of a silver target and subsequently their transport for deposition on a distant substrate. The nanofeatures and functionality of the nanoparticles, entrained and deposited with the two plasma jets were compared using high-resolution electron microscopy, helium ion microscopy, scanning electron microscopy, ultraviolet–visible spectroscopy, and in terms of the SERS effect. The plasma jet facilitates the transport of the particle aerosol under the upshot of plasma ionic wind, caused by the high electric field in the plasma. Compared to the helium plasma jet, the argon plasma jet leads to a relatively large particle deposition and promotes the formation of aggregates. The helium plasma jet enabled ...

Cold atmospheric plasma (CAP) is a promising tool to overcome certain cancerous and precancerous conditions in dermatology. A scheme of transferred CAP was first developed to treat melanoma (B16F10) skin cancer cells as well as non-malignant (L929) cells in vitro. CAP was transferred using a silicone tube with a jet system that was developed and was assessed as to whether it could generate reactive oxygen and nitrogen species (RONS) at near-room temperature. The transferred CAP was characterized electrically and spectroscopically. Biological data showed that the transferred CAP killed cancer cells but not non-malignant (L929) cells. Plasma treatment was effective with a time duration of 30 s, whereas non-malignant (L929) cells were less damaged during plasma treatment. In addition, catalase (CAT) enzyme was applied to neutralize and detoxify the RONS generated by the transferred CAP. These findings suggest that transferred CAP can be considered a melanoma cancer therapy.

The direct application of cold atmospheric plasma (CAP) is the main scope of plasma medicine in or on the organism for curative purposes. Cold plasma is both effective in disrupting a wide range of microorganisms including multiple drug resistant ones (MDRs) and to stimulate proliferation of mammalian cells. It has obtained by Floating Electrode Dielectric Barrier Discharge (FE-DBD) system. The present study aimed to show the effected of cold plasma on the fertility hormones LH, Prolactin, Estrogen, and Testosterone hormones for healthy adult female rats (Albino) / bulb c). There are divided into many groups according to time exposure of plasma (15, 30, 60, and 90 second) and a reference group (without plasma exposure), with different time intervals after exposure (1, 2, 3, 7, 14, 28 days). The concentration of hormones was measured using Enzyme Linked Immunosorbent Assay (ELISA). The results showed that, the CAP effected slightly on the Luteinizing Hormone (LH) and Estradiol Hormon...

Despite recent advances in therapy, cancer still is a devastating and life-threatening disease, motivating novel research lines in oncology. Cold physical plasma, a partially ionized gas, is a new modality in cancer research. Physical plasma produces various physicochemical factors, primarily reactive oxygen and nitrogen species (ROS/RNS), causing cancer cell death when supplied at supraphysiological concentrations. This review outlines the biomedical consequences of plasma treatment in experimental cancer therapy, including cell death modalities. It also summarizes current knowledge on intracellular signaling pathways triggered by plasma treatment to induce cancer cell death. Besides the inactivation of tumor cells, an equally important aspect is the inflammatory context in which cell death occurs to suppress or promote the responses of immune cells. This is mainly governed by the release of damage-associated molecular patterns (DAMPs) to provoke immunogenic cancer cell death (ICD)...

Low-temperature, high-pressure plasma jets have an extensive use in medical and biological applications. Much work has been devoted to study these applications while comparatively fewer studies appear to be directed to the discharge itself. In this work, in order to better understand the kind of electrical discharge and the plasma states existing in those devices, a study of the electrical characteristics of a typical plasma jet, operated at atmospheric pressure, using either air or argon, is reported. It is found that the experimentally determined electrical characteristics are consistent with the model of a thermal arc discharge, with a highly collisional cathode sheet. The only exception is the case of argon at the smallest electrode separation studied, around 1 mm in which case the discharge is better modeled as either a non-thermal arc or a high-pressure glow. Also, variations of the electrical behavior at different gas flow rates are interpreted, consistently with the arc model, in terms of the development of fluid turbulence in the external jet. V

Low-temperature, high-pressure plasma jets have an extensive use in medical and biological applications. Much work has been devoted to study these applications while comparatively fewer studies appear to be directed to the discharge itself. In this work, in order to better understand the kind of electrical discharge and the plasma states existing in those devices, a study of the electrical characteristics of a typical plasma jet, operated at atmospheric pressure, using either air or argon, is reported. It is found that the experimentally determined electrical characteristics are consistent with the model of a thermal arc discharge, with a highly collisional cathode sheet. The only exception is the case of argon at the smallest electrode separation studied, around 1 mm in which case the discharge is better modeled as either a non-thermal arc or a high-pressure glow. Also, variations of the electrical behavior at different gas flow rates are interpreted, consistently with the arc model, in terms of the development of fluid turbulence in the external jet. V

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The lattice Boltzmann method (LBM) is an alternative method to the conventional computational fluid dynamic (CFD) methods. It gained popularity due to its simplicity in coding and dealing with a complex fluid flow such as the multiphase flow. The method is based on the kinetic theory, which is mesoscopic scale. Hence, applying the LBM method for macroscopic problems requires a proper conversion from the physical scale (conventional units) to the mesoscopic scale (lattice units) and vice versa. The Buckingham π theorem and the principle of corresponding states are the popular methods used for data reductions and unit conversion processes in the LBM. Nevertheless, those methods have some issues, such as difficulty in converting specific quantities, such as thermo-physical properties. The current work uses a novel dimensional analysis method systematically for mapping properties' units between scales. Moreover, the approach has the flexibility in selecting parameters to ensure the stability of the method of solution. Several benchmark examples are used to evaluate the feasibility and accuracy of the proposed approach. In conclusion, the proposed approach showed the flexibility of the mapping between meso-scale to macro-scales and vice versa on solid bases rather than ad-hoc methods.

Rich in reactive oxygen and nitrogen species, cold atmospheric plasma has been shown to effectively control events critical to cancer progression; selectively inducing apoptosis, reducing tumor volume and vasculature, and halting metastasis by taking advantage of, e.g., synergies between hydrogen peroxide and nitrites. This paper discusses the efficacy, safety and administration of cold atmospheric plasma treatment as a potential tool against cancers, with a focus on the mechanisms by which cold atmospheric plasma may affect critical transitional switches that govern tumorigenesis: the life/death control, tumor angiogenesis and epithelial–mesenchymal transition, and drug sensitivity spectrum. We introduce the possibility of modeling cell transitions between the normal and cancerous states using cold atmospheric plasma as a novel research avenue to enhance our understanding of plasma-aided control of oncogenesis.

Properties of nitrogen cluster plasmas produced by an intense, ultrashort laser pulse have been investigated numerically and experimentally. The classical dynamics simulations show that on increasing the cluster size a plasma with residual electron energy above 1 keV can be created due to collisional heating, which is considerably higher than the value obtained with a conventional low-density gas target. Experimentally, nitrogen gas jets created by two types of nozzles were irradiated with a laser pulse of 55 fs, up to 1.2ϫ 10 17 W/cm 2. A seeded gas jet consisting of nitrogen and helium was also employed to promote the production of large clusters. The influences of the shape of nozzle, the seeded gas, and the gas jet stagnation pressure on the properties of plasmas were examined by spectroscopic observations. K-shell emissions showed that for the gas jet using the conical nozzle the electrons underwent intense collisional heating within the large clusters, resulting in the production of highly charged ions. In contrast, the emissions observed with the capillary nozzle exhibited the characteristics of a cold plasma without suffering substantial electron heating, indicating the absence of large clusters. That is, the differences between the two types of nozzles in the efficiency of electron heating and subsequent residual energies after the passage of the laser pulse, which are strongly dependent upon the cluster size, drastically changed the properties of the produced plasmas. The reason that for the capillary gas jet the plasma density deduced from the recombination spectra was significantly higher than the value obtained using the conical nozzle is also given by the difference in residual electron energy.

As a new field of oxidative stress-based therapy, cold physical plasma is a promising tool for several biomedical applications due to its potential to create a broad diversity of reactive oxygen and nitrogen species (RONS). Although proposed, the impact of plasma-derived RONS on the cell membrane lipids and properties is not fully understood. For this purpose, the changes in the lipid bilayer functionality under oxidative stress generated by an argon plasma jet (kINPen) were investigated by electrochemical techniques. In addition, liquid chromatography-tandem mass spectrometry was employed to analyze the plasma-induced modifications on the model lipids. Various asymmetric bilayers mimicking the structure and properties of the erythrocyte cell membrane were transferred onto a gold electrode surface by Langmuir-Blodgett/Langmuir-Schaefer deposition techniques. A strong impact of cholesterol on membrane permeabilization by plasma-derived species was revealed. Moreover, the maintenance ...

The biological effects induced by cold atmospheric plasmas (CAPs) on human tissues are mainly due to the production of reactive oxygen and nitrogen species (RONS). Some RONS are also responsible for pH lowering of the treated medium. The CAP-induced acidification has beneficial effect on biological tissues, contributing to the anti-bacterial effect and to the healing improvement observed in treated wound. In this work we investigated the local acidification induced by a helium CAP treatment using tissue models made of agarose gels with adjusted pH around 7.4 to mimic generic organs or around 5.5 to simulate skin surface pH. Using fluorescein as a pH-sensitive fluorescent marker, we developed a useful technique to visualize and quantify the local acidification induced by CAP exposure of tissue surface. The different capillaries used to produce the plasma jet, the treatment time, the initial pH of the surface and the buffer capacity of the tissue model were shown to modulate both the size of the impacted surface and the intensity of the pH decrease. The proposed technique can be advantageous to study the acidifying effect induced by plasma. This method can help to plan safe and controlled plasma treatments in order to avoid hyper-acidification of the tissue, especially when a localized treatment is administered.

The aim of this work presents the characterization of a plasma jet powered by Tesla coil. Tesla coil can be used for generation cold plasma from Dielectric Barrier Discharge (DBD). Tesla coil has been designed and constructed at Egyptian Atomic Energy Authority for multipurpose. The electrical characteristic of non-equilibrium plasma jet using rare gases (argon and helium) at atmospheric pressure has been studied. An atmospheric-pressure cold plasma jet generated by Tesla coil in a single-electrode configuration is characterized based on optical and electrical measurements.

Space and time resolved concentrations of Ar (3 P 2) metastable atoms at the exit of an atmospheric pressure radio-frequency micro-plasma jet were measured using tunable diode laser absorption spectroscopy. The discharge features a coaxial geometry with a hollow capillary as an inner electrode and a ceramic tube with metal ring as outer electrode. Absorption profiles of metastable atoms as well as optical emission measurements reveal the dynamics and the filamentary structure of the discharge. The average spatial distribution of Ar metastables is characterized with and without a target in front of the jet, showing that the target potential and therewith the electric field distribution substantially changes the filaments' expansion. Together with the detailed analysis of the ignition phase and the discharge's behavior under pulsed operation, the results give an insight into the excitation and de-excitation mechanisms.

Glioma is the most common type of brain cancer. Chemotherapy combination with surgery and radiotherapy is a standard treatment for patients. Although there are many advances in glioma therapy, the prognosis of glioma patients has not significantly been improved over the past decades. Hence, there is still an urgent need to develop a new therapy to treat glioma. Cell viability was assessed by CellTiter Blue assay; flow cytometry (FCM) was used for detecting cell apoptosis; ROS detection was detected by ROS Assay; H2O2 detection was performed by hydrogen peroxide detection kits; real-time PCR and WB were used to determine gene expression. Using the glioma cell line U251 and U87, we investigated a possible combination inhibitory effect includes metformin and cold atmospheric plasma (CAP). The combination treatment showed a synergistic inhibitory effect on cell viability, significantly inducing cell apoptosis. Furthermore, we also found H2O2 produced by CAP has an important role in the synergistic inhibitory effect, eliminating H2O2 with catalase reversed the synergistic inhibitory effect. In addition, the transcript and protein levels of c-FOS were robustly increased after co-treated with metformin and CAP. Taken together, we propose that pre-treatment of glioma cells with metformin sensitize tumor cells to CAP, which may serve as a potential therapeutic strategy for glioma.

This work presents the numerical simulation of the melting process of a particle injected in a plasma jet. The plasma process is nowadays applied to produce thin coatings on metal mechanical components with the aim of improving the surface resistance to different phenomena such as corrosion, temperature or wear. In this work we studied the heat transfer including phase-change of a bi-layer particle composed of a metallic iron core coated with ceramic alumina, inside a plasma jet. The model accounted for the environmental conditions along the particle path. The numerical simulation of this problem was performed via a temperature-based phase-change finite element formulation. The results obtained with this methodology satisfactorily described the melting process of the particle. Particularly, the results of the present work illustrate the phase change evolution in a bi-layer particle during its motion in the plasma jet. Moreover, the numerical trends agreed with those previously reported in the literature and computed with a finite volume enthalpy based formulation.