Andrei Vasile Nastuta

Atmospheric pressure plasma jet—Living tissue interface: Electrical, optical, and spectral characterization

The atmospheric pressure plasma jet is studied as potential plasma source for medical applications in direct contact with living tissues. Plasma bullets are generated in the region of the high voltage electrode and propagate towards the tissue surface. The presence of a localized plasma structure on tissues, played here by a human fingertip, is experimentally revealed. It was found that this plasma structure is sustained by a current flowing through the tissue, with the magnitude dependent on the distance from the discharge tube. The characteristic time span of the plasma at the interface is up to 20 μs and the diameter up to 5 mm. These parameters were studied using the two independent techniques: ultra-fast imaging and photomultiplier measurements. Generation of supplementary reactive species at the interface, the NO molecules, was proved by optical emission spectroscopy.The atmospheric pressure plasma jet is studied as potential plasma source for medical applications in direct contact with living tissues. Plasma bullets are generated in the region of the high voltage electrode and propagate towards the tissue surface. The presence of a localized plasma structure on tissues, played here by a human fingertip, is experimentally revealed. It was found that this plasma structure is sustained by a current flowing through the tissue, with the magnitude dependent on the distance from the discharge tube. The characteristic time span of the plasma at the interface is up to 20 μs and the diameter up to 5 mm. These parameters were studied using the two independent techniques: ultra-fast imaging and photomultiplier measurements. Generation of supplementary reactive species at the interface, the NO molecules, was proved by optical emission spectroscopy.

On the Discharge Parameters of a Glow-Mode DBD at Medium and Atmospheric Pressure

In this paper, we report on the behavior of a glow-mode pulsed barrier discharge working at different gas pressure (25-760 torr) in helium and helium-oxygen gas mixture. The experimental setup consists of a plane-parallel geometry of a dielectric barrier discharge (DBD) system, excited by positive monopolar voltage pulses. The discharge properties were characterized by electrical measurements and emission spectroscopy. Our investigations showed that the discharge consists of two current pulses, with different polarities, corresponding to each voltage pulse. The main results referred to the effect of pressure and oxygen percentage on the discharge parameters. The time-resolved spectroscopy of the DBD plasma working at different pressure pointed out the differences between the discharge mechanism at medium pressure and that close to atmospheric pressure. Moreover, at medium pressure (25 torr), the oxygen atoms are efficiently created for about 2% of molecular oxygen added to gas mixture.

ICCD Imaging of Atmospheric Pressure Plasma Jet Behavior in Different Electrode Configurations

Nowadays, atmospheric pressure plasma jets using a dielectric-barrier discharge with an axial symmetry configuration attract the interest of many researchers. However, the mechanisms responsible for the generation of atmospheric plasma jets still remain unknown. In this paper, using intensified charge-coupled device images, we present the “bulletlike” structures of a plasma jet traveling at supersonic velocities.

Carbon and Tungsten Sputtering in a Helium Magnetron Discharge

This study reports on carbon and tungsten deposition on a heated silicon substrate under He+ bombardment in a magnetron sputtering device. The discharge was operated at constant pressure of 1.33 Pa for two discharge current intensities (200 mA and 600 mA) and target power density up to 40 Wcm-2. The deposited films were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffractometry (XRD). The topography and cross section reveals the influence of the target power density on the surface roughness, grains size and thickness of the deposited films.

Diagnosis of a short-pulse dielectric barrier discharge at atmospheric pressure in helium with hydrogen-methane admixtures

In this study, we present results from electrical, optical, and spectroscopic diagnosis of a short-pulse (250 ns) high-power impulse (up to 11 kW) dielectric barrier discharge at atmospheric pressure running in a helium/helium-hydrogen/helium-hydrogen-methane gas mixture. This plasma source is able to generate up to 20 cm3 of plasma volume, pulsed in kilohertz range. The plasma spatio-temporal dynamics are found to be developed in three distinct phases. All the experimental observations reveal a similar dynamic to medium power microsecond barrier discharges, although the power per pulse and current density are up to two orders of magnitude higher than the case of microsecond barrier discharges. This might open the possibility for new applications in the field of gas or surface processing, and even life science. These devices can be used in laboratory experiments relevant for molecular astrophysics.

Assessing potential dietary toxicity of heavy metals in lingonberry from Mănăila open-pit area (Suceava, Romania)

In this study, the content of heavy metals was determined in berries and leaves of lingonberry (Vaccinum vitisidaea) by inductively coupled plasma mass spectrometry (ICPMS). Samples of lingonberry plant were collected from surroundings of open pit mining area of metallic sulphides bearing mineralization from Mănăila (Suceava County). On the base of legislative permissible limits, the berries and leaves show that the contamination is minimal for Cu, Zn and Pb, while a special attention should be paid to Mn content. The calculated health risk index is lower than unit for most of the heavy metals, except for Mn. This infers no risk of consumption since the fresh berries are used for a short period of time. If the berries and leaves are used for pharmaceutical extracts, the Mn effect would be diminished by mixing with those from uncontaminated areas. Generally, the lingonberries from Mănăila can be regarded as safety, as long as they are not used in daily dietary.

Monitoring Hand Gesture and Effort Using a Low-Cost Open-Source Microcontroller System Coupled with Force Sensitive Resistors and Electromyography Sensors

In this study, we consider a low-cost open-source environment, where users interact with several computing devices and platforms. Thus, the specific usage of any tool requires a specific configuration process in order to meet the end user’s needs. The aim is to compare the effectiveness of hand gesture recognition using electromyography (EMG) electrodes when using sensors located on the forearm in comparison to force-sensitive resistor (FSR) array located over the fingers of the hand. Our study involves monitoring the movement of the fingers in a single (angular) direction corresponding to gestures of gripping and releasing objects (a single degree of freedom). Our interest is in how the relocation of sensors would affect the classification rates of finger gestures. Our study confirmed that by including EMG along the FSR sensors the classification rate for different kinds of gesture (including all fingers and wrist) increased, providing a better understanding of the complex hand dynamics. These findings can be used in machine learning systems for developing versatile hand prosthesis or in rehabilitation.

On the discharge parameters of a glow mode DBD

In this paper we report on the behavior of a glow mode pulsed barrier discharge working at different gas pressure (25-760 Torr) in He and He+O2. The experimental set-up consists of a plane-parallel geometry of DBD system, excited by positive monopolar voltage pulses. The discharge properties were characterized by electrical measurements and emission spectroscopy. Our investigations showed that the discharge consists of two current pulses, with different polarities, corresponding to each voltage pulse. The main results referred to the effect of pressure and oxygen percentage on the discharge parameters. The temporally resolved spectroscopy of the DBD plasma working at different pressure pointed out the differences between the discharge mechanism at low pressure and that closed to atmospheric pressure. At low pressure (25 Torr), the oxygen atoms are efficiently created for about 2% of oxygen added to gas mixture.