Search

A semicombustible plasma generator (SCPG), including a special tubular semicombustible medium, is introduced to improve the discharge property of the plasma generator and enhance the electrothermal–chemical (ETC) launch efficiency. The new structure of SCPG is mixed with both capillary plasma generator (CPG) and discharge rod plasma generator (DRPG). After the design and simulation, the electrical characteristics of this SCPG are discussed with both static test and dynamic tests. Results show that the SCPG is a resistive load with low inductance, which has stable and consistent electrical parameters. With the increase of discharge voltage, the peak current of SCPG is increased and the equivalent resistance of SCPG is decreased. The peak voltage is nearly 1.3 kV and the pulse current bottom width is more than 3.5 ms. Compared with the DRPG, the load characteristics of SCPG are in a stable and consistent trend during the pulsed discharge process as the same as DRPG. Also, the SCPG has longer stable working times and better stable working parameters and performance. This SCPG will promote the interaction between the plasma and propellants in the chamber.

Application of an energetic material (EM) in a liquid or gaseous form to electrothermal (ET) plasma discharge systems can provide an energetic plasma jet that has desirable parameters for launching applications. In this energetic ET concept, the EM is basically injected into the plasma source that is operated in an ablation-free regime. The discharge and EM combustion processes have been simulated using the ETFlowCom code, which is an in-house developed energetic ET plasma model. In this article, the ETFlowCom code is used to predict the energetic plasma jet parameters such as temperature, pressure, heat flux, and exit velocity. Different computational case studies have been conducted using a variety of EM mixtures. The simulation results show that the generated energetic plasma jet has the density on the order of 10271/m3, kinetic pressure on the order of hundreds of MPa, and an exit velocity that can reach up to 6 km/s. These parameters are found to be functions of the EM type and the mixing ratio as well. The jet parameters show strong potential for launching applicability.

This work presents the development of an electrochemical microsystem for antipsychotic clozapine treatment monitoring in schizophrenia patients. In our previous work, we demonstrated clozapine detection directly in spiked whole blood samples of a healthy volunteer using a chitosan–carbon nanotube-modified microelectrode with external counter and reference electrodes. Here we present the miniaturization of our previous clozapine sensing approach and its clinical validation in real samples obtained from 10 schizophrenia patients. We observed a sensitivity of 0.02 ± 2.3 × 10-4 mA/cm2µM and 0.003 ± 2.6 × 10-4 mA/cm2µM and a limit of detection of 0.08 ± 9.2 × 10-4 µM and 0.45 ± 0.04 µM using chitosan–carbon nanotube-modified microelectrodes in a 20 µL volume of spiked capillary plasma and capillary whole blood. Following a calibration curve, which was obtained from spiked samples of patients prior to clozapine therapy administration, clozapine capillary plasma and whole blood levels were recovered from patients’ samples after treatment with clozapine. The developed electrochemical microsystem allows clozapine analysis in a microliter volume of finger-pricked whole blood samples of schizophrenia patients without using any pretreatment steps. By further miniaturization and integration of this sensor into a point-of-care testing device, schizophrenia treatment management can be improved.

Plasma wake-field acceleration experiments are performed at the SPARC_LAB test facility by using a gas-filled capillary plasma source composed of a dielectric capillary. The electron can reach GeV energy in a few centimeters, with an accelerating gradient orders of magnitude larger than provided by conventional techniques. In this acceleration scheme, wake fields produced by passing electron beams through dielectric structures can determine a strong beam instability that represents an important hurdle towards the capability to focus high-current electron beams in the transverse plane. For these reasons, the estimation of the transverse wake-field amplitudes assumes a fundamental role in the implementation of the plasma wake-field acceleration. In this work, it presented a study to investigate which parameters affect the wake-field formation inside a cylindrical dielectric structure, both the capillary dimensions and the beam parameters, and it is introduced a quantitative evaluation of the longitudinal and transverse electric fields.

Optically thick spectral line emssion from plasmas is often difficult to use for the diagnosis of plasma parameters. We demonstrate a technique for temperature measurement using the peak intensity of optically thick lines as their intensities approach a black-body distribution. Recording optical emission in the wavelength range 300–1000 nm from a plasma formed by radio-frequency heating and electrical discharges in a 0.2 m long capillary plasma, we show that the high wavelength Rayleigh-Jeans form of the black-body emission can be fitted to the most intense spectral lines to give a measurement of plasma temperatures in the 1–1.5 eV range. The temperature measurement technique should have wider applicability in diagnosing plasmas with optically thick spectral lines.

The jet expansion behaviors of ablating-capillary plasma used in the liquid propellant electrothermal chemical gun were investigated. A pulsed power system was built up to drive the arc plasma generator by high-voltage discharge in polyethylene capillary. The temporal evolutions of the arc plasma jet in both open air and bulk-loaded liquid were analyzed with high-speed imaging and dynamic pressure measurements. The arc plasma jet exhibited rapid axial expansion and strongly turbulent mixing with the ambient fluids. Experiments conducted with different discharge voltages showed that the voltage had a significant effect on the axial expanding speed of the arc plasma jet. A 2-D magneto-hydrodynamic model, which consisted of several submodels, such as the capillary ablation model, the species ionization model, the high-temperature radiation model, and the turbulent model, was developed to describe the generation and evolution of arc plasma jet. Good agreements between calculations and experiments in the aspects of jet contours and pressure histories indicated that the current model had the capacity to capture the major physical features of the ablating-capillary arc plasma jet.

Background: A considerable challenge in quantification of the antimalarial piperaquine in plasma is carryover of analyte signal between assays. Current intensive pharmacokinetic studies often rely on the merging of venous and capillary sampling. Drug levels in capillary plasma may be different from those in venous plasma, Thus, correlation between capillary and venous drug levels needs to be established.Methods: Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was used to develop the method. Piperaquine was measured in 205 pairs of capillary and venous plasma samples collected simultaneously at ≥24hr post dose in children, pregnant women and non-pregnant women receiving dihydroartemisinin-piperaquine as malaria chemoprevention. Standard three-dose regimen over three days applied to all participants with three 40mg dihydroartemisinin/320mg PQ tablets per dose for adults and weight-based dose for children. Correlation analysis was performed using the program Stata® SE12.1. Linear regression models were built using concentrations or logarithm transformed concentrations and the final models were selected based on maximal coefficient of determination (R2) and visual check.Results: An LC-MS/MS method was developed and validated, utilizing methanol as a protein precipitation agent, a Gemini C18 column (50x2.0mm, 5μm) eluted with basic mobile phase solvents (ammonium hydroxide as the additive), and ESI+ as the ion source. This method had a calibration range of 10-1000 ng/mL and carryover was negligible. Correlation analysis revealed a linear relationship: Ccap = 1.04×Cven+4.20 (R2 = 0.832) without transformation of data, and lnCcap = 1.01×lnCven+0.0125, (R2 = 0.945) with natural logarithm transformation. The mean ratio (±SD) of Ccap/Cven was 1.13±0.42, and median (IQR) was 1.08 (0.917, 1.33).Conclusions: Capillary and venous plasma PQ measures are nearly identical overall, but not readily exchangeable due to large variation. Further correlation study accounting for disposition phases may be necessary.

Serologic testing for SARS-CoV-2 antibodies can be used to confirm diagnosis, estimate seroprevalence, screen convalescent plasma donors, and assess vaccine efficacy. Several logistical and infrastructure challenges limit access to SARS-CoV-2 serologic testing. Dried blood spot (DBS) samples have been used for serology testing of various diseases in resource-limited settings. We examined the use of DBS samples and capillary blood (fingerstick) plasma collected in Microtainer tubes for SARS-CoV-2 testing with the automated Abbott ARCHITECT™ SARS-CoV-2 IgG (List 6R86) and IgM assays and use of venous whole blood with a prototype PANBIO™ rapid point-of-care lateral flow SARS-CoV-2 IgG assay. The ARCHITECT™ SARS-CoV-2 IgG assay was initially optimized for use with DBS, venous and capillary plasma, and venous whole blood collected from patients with symptoms and PCR-confirmed COVID-19 and negative asymptomatic controls. Assay linearity and reproducibility was confirmed with 3 contrived DBS samples, with sample stability and signal recovery after 14 days at room temperature. ARCHITECT™ SARS-CoV-2 IgG and IgM assay results showed high concordance between fingerstick DBS and venous DBS samples, and between fingerstick DBS and venous whole blood samples (n=61). Discordant results were seen in 3 participants (2 IgG, 1 IgM) who were in the process of seroreversion at the time of sample collection and had results near the assay cutoff. Use of fingerstick plasma collected in Microtainer tubes (n=109) showed 100% concordant results (R2=0.997) with matched patient venous plasma on the ARCHITECT™ SARS-CoV-2 IgG assay. High concordance of assay results (92.9% positive, 100% negative) was also observed for the PANBIO™ SARS-CoV-2 IgG assay compared to the ARCHITECT™ SARS-CoV-2 IgG assay run with matched venous plasma (n=61). Fingerstick DBS and plasma samples are easy and inexpensive to collect and, along with the use of rapid point-of-care testing platforms, will expand access to SARS-CoV-2 serology testing, particularly in resource-limited areas.

Electrothermal (ET) plasma discharges have application to mass acceleration technologies relevant to military ballistics and magnetic confinement fusion reactor operation. ET plasma discharges are initiated in capillary geometries by passing large currents (order of tens of kiloamperes) along the capillary axis. A partially ionized plasma then forms and radiates heat to the capillary walls inducing ablation. Ablated particles enter the capillary plasma source and cause a pressure surge that can propel pellets to velocities exceeding 2 km/s. These devices present several advantages over other mass accelerator technologies due to their simple design and ability to achieve high projectile launch frequencies. In order to investigate the operation of ET plasma discharges in more detail than previously possible, a 2-D, multifluid model has been developed to simulate the plasma-fluid dynamics that develop in these devices during operation. In this paper, the 2-D simulation model is used to investigate the effect of source geometry and current density on discharge characteristics. Peak pressure and electric field magnitudes for pulsed discharge operation are shown to scale well with theoretical and empirical scaling laws for steady-state discharge operation. The pulse shape of the source internal pressure is shown to change significantly with increasing source radius. The behavior of other plasma parameters is investigated. In addition, observations of the departure from the ablation-controlled arc regime are presented. This analysis suggests that, for the current pulse length investigated, source radii higher than 4 mm require significantly more current density in order to produce sufficient ablation to stabilize the plasma discharge.

Quantification of blood levels of antipsychotic drugs may be useful for managing medication therapy. This open‐label, parallel‐group study was performed to compare finger‐stick‐based capillary with corresponding venous plasma concentrations for risperidone, paliperidone, quetiapine, olanzapine, and aripiprazole and their major metabolites after repeated dosing in patients with schizophrenia or related illnesses. Finger‐stick‐based capillary and venous blood samples were collected at various times within a dosing interval. All drug concentration measurements in the derived plasma samples were performed with validated liquid chromatography–tandem mass spectrometry methods. Finger‐stick‐based capillary and venous plasma drug concentrations after repeated dosing were generally similar. Olanzapine capillary plasma concentrations, however, were on average approximately 20% higher than venous concentrations, with a trend for a relatively greater difference occurring shortly after dosing. In addition, smaller capillary–venous differences were observed for extended‐release and long‐acting intramuscular formulations and for aripiprazole, a drug with a long half‐life, compared with drugs administered as an immediate‐release formulation (risperidone, olanzapine). After repeated dosing, plasma derived from finger‐stick‐based blood was observed to be predictive of the venous concentrations. Capillary sampling may be an appropriate alternative to venous sampling to readily evaluate systemic drug concentrations.

Background An automated multiplex platform using capillary blood can promote greater throughput and more comprehensive studies in celiac disease (CD). Diagnostic accuracy should be improved using likelihood ratios for the post-test probability of ruling-in disease. Methods The Ig_plex™ Celiac Disease Panel on the sqidlite™ automated platform measured IgA and IgG antibodies to tTG and DGP in n = 224 CD serum or plasma samples. Diagnostic accuracy metrics were applied to the combined multiplex test results for several CD populations and compared to conventional single antibody ELISA tests. Results With multiple positive antibody results, the post-test probability for ruling-in untreated and treated CD increased to over 90%. The number of samples positive for more than one antibody also increased in untreated CD to ≥90%. Measurement of all four CD antibodies generate cut-off dependent accuracy profiles that can monitor response to treatment with the gluten-free diet (GFD). Higher positive tTG and DGP antibodies are seen more frequently in confirmed CD without (81%–94%) than with GFD treatment (44%–64%). In CD lacking biopsy confirmation, overall agreement of plasma to serum was ≥98% for all antibodies, and 100% for venous to capillary plasma. Conclusions The Ig_plex Celiac Disease Panel increases the likelihood of confirming CD based on the post-test probability of disease results for multi-reactive markers. Specific positivity profiles and cut-off intervals can be used to monitor GFD treatment and likely disease progression. Using serum, venous and capillary plasma yield comparable and accurate results.

The concept of tapered capillary is introduced as a method of injecting focused plasma jet into the breach of bulk-loaded electrothermal-chemical (ETC) launcher. Tapered capillaries will operate in the confined controlled arc regime, and they can provide the advantage of producing focused hyper plasma jets useful for ignition of ETC systems at controlled plasma temperatures and pressures. The concept is also useful for focused implantation of plasma ions on substrates with desired patterns. Such tapered capillaries can inject plasmas at peak kinetic temperatures in the range of 14000-21000 K (~1.2-1.8 eV) and considerable jet pressures of 10-70 MPa for an input discharge current of 20-30 kA over a short pulselength of 100-150 μs. A tapered geometry made of Lexan polycarbonate with 16.8-mm inlet and 8.8-mm outlet radii produces a plasma jet with a plasma temperature of 14253 K (1.23 eV) at a peak bulk velocity of 4.027 km/s with a 10.38-MPa exit pressure, and a total ablated mass of 10.56 mg. Reducing the tapering to 12.6-mm inlet and 6.6-mm outlet radii produces a plasma jet with a plasma temperature of 16382-K (1.411 eV) at a bulk velocity of 4.34 km/s and a total of 23.27-mg ablated mass. Further reduction in the tapering to 8.4-mm inlet and 4.4-mm outlet radii produces a plasma jet with a plasma temperature of 20954 K (1.8 eV) at a bulk velocity of 4.89 km/s with a 70.78-MPa exit pressure, and a total ablated mass of 15.09 mg. The preliminary study shows that the narrow tapering angle produces higher pressure, temperature, velocity, and more ablated mass. Radiant heat flux at the taper exit varies from 2.2 GW/m 2 for the wider tapers to 6.24 GW/m 2 for the narrower ones.

Previous published results of closed vessel investigations indicated that classical primers (electric or percussion with black powder bedding) when used with LOVA propellants cause unstable burning, deflagration or even lack of ignition. Capillary Plasma Generator is one of the most reliable ignition sources which make possible a reduction of temperature gradient effect and control combustion process. Comparable tests of black powder and plasma ignition in closed vessel with conventional NC propellant were done. Shorter ignition time while using plasma was achieved.

Atmospheric-pressure discharge in the tubular capillary plasma jet was studied to reveal the possibility to accelerate anodization of aluminum foils and fabricate alumina nanoparticles in liquid acids. Two different positions of the atmospheric pressure plasma jet relatively to the acid electrolyte and aluminum electrode were studied. Whereas at larger distances, only slight oxidation was obtained, the nanoporous surface and alumina nanoparticles were produced at closer (3–5 mm) distances. The mode with arcing (sparking) resulted in the film of alumina nanoparticles. The obtained results could be useful for the cheap and convenient synthesis of nanoparticles and nanostructured surfaces for various applications, including medical, biological, energy conversion, and nanoelectronic devices.

Analytica Chimica Acta, 1030, ISSN:0003-2670, ISSN:1873-4324

Background Lumefantrine is a long-acting antimalarial drug with an elimination half-life of over 3 days and protein binding of 99 percent. Correlation of lumefantrine concentrations from capillary plasma via fingerprick (Cc) versus venous plasma (Cv) remains to be defined. Methods Venous and capillary plasma samples were collected simultaneously from children, pregnant women, and non-pregnant adults at 2, 24, 120hr post last dose of a standard 3-day artemether-lumefantrine regimen they received for uncomplicated malaria. Some of the enrolled children and pregnant women were also HIV-infected. Samples were analyzed via liquid chromatography tandem mass spectrometry. Linear regression analysis was performed using the program Stata® SE12.1. Results In children, the linear regression equations for Cc vs Cv at 2, 24, and 120hr (day 7) post dose are [Cc] = 1.05*[Cv]+95.0 (n = 142, R2 = 0.977), [Cc] = 0.995*[Cv]+56.7 (n = 147, R2 = 0.990) and [Cc] = 0.958*[Cv]+18.6 (n = 139, R2 = 0.994), respectively. For pregnant women, the equations are [Cc] = 1.04*[Cv]+68.1 (n = 43, R2 = 0.990), [Cc] = 0.997*[Cv]+37.3 (n = 43, R2 = 0.993) and [Cc] = 0.941*[Cv]+11.1 (n = 41, R2 = 0.941), respectively. For non-pregnant adults, the equations are [Cc] = 1.05*[Cv]-117 (n = 32, R2 = 0.958), [Cc] = 0.962*[Cv]+9.21 (n = 32, R2 = 0.964) and [Cc] = 1.04*[Cv]-40.1 (n = 32, R2 = 0.988), respectively. In summary, a linear relationship with a slope of ~1 was found for capillary and venous lumefantrine levels in children, pregnant women and non-pregnant adults at 2hr, 24hr and 120hr post last dose, representing absorption, distribution, and elimination phases. Conclusions Capillary and venous plasma concentration of lumefantrine can be used interchangeably at 1:1 ratio. Capillary sampling method via finger prick is a suitable alternative for sample collection in clinical studies.

To investigate the kinetics of cell-free DNA (cfDNA) due to exercise, we established a direct real-time PCR for the quantification of cfDNA from unpurified capillary plasma by amplification of a 90- and a 222-bp multilocus L1PA2 sequence. Twenty-six male athletes performed an incremental treadmill test. For cfDNA measurement, capillary samples were collected serially from the fingertip preexercise, during, and several times postexercise. Venous blood was drawn before and immediately after exercise to compare capillary and venous cfDNA values. To elucidate the strongest association of cfDNA accumulations with either cardiorespiratory or metabolic function during exercise, capillary cfDNA values were correlated with standard measures like heart rate, oxygen consumption, or lactate concentrations. The venous cfDNA concentrations were significantly higher compared with the capillary plasma, but in both fractions cfDNA increased 9.8-fold and the values correlated significantly ( r = 0.796). During incremental treadmill running, the capillary cfDNA concentrations increased nearly parallel to the lactate values. The values correlated best with heart rate and energy expenditure, followed by oxygen consumption, Borg values, and lactate levels (0.710 ≤ r ≥ 0.808). With this article, we present a sensitive procedure for the direct quantification of cfDNA in unpurified capillary plasma instead of purified venous plasma. Further studies should investigate the differences between capillary and venous cfDNA that might mirror different physiological mechanisms. Enhanced cardiorespiratory function during exercise might lead to the accumulation of cfDNA via the release of stress hormones that already increase at intensities below the anaerobic threshold. Furthermore, cfDNA might be released by neutrophil extracellular traps.

Plasma viscosity (PV) and erythrocyte sedimentation rate (ESR) are tests which can be used as inflammation and tissue injury markers [2, 11]. ESR usage is more extended than PV in clinical laboratories. However ESR may be haematocrit (Ht) dependent and is related with red blood cell (RBC) rheological properties [1], whereas RBC are not involved in PV. We aimed to evaluate retrospectively the impact of Ht on ESR as an inflammatory marker and compare the results with those of PV in 333 outand in-patients at our hospital. Our study is a human non-interventional retrospective review and written consent is not required for human non-interventional studies. We evaluated both markers in two patient groups of i.e., the first one did not present other inflammatory components measured as C-reactive protein (CRP) below 10 mg/L and fibrinogen below 450 mg/dL (n= 211). The second one presented CRP over 10 mg/L and/or fibrinogen values higher than 450 mg/dL (n= 122). PV and ESR were determined in a capillary plasma viscosimeter (Fresenius GmbH, Germany) at 37◦C and using a Ves matic 30 Plus Analyzer (Diesse Diagnostica Senese, Siena, Italy), respectively. CRP was determined by immunoturbidity in an AU5430 autoanalyzer (Beckman Coulter, Lexington, KY, USA) and fibrinogen analysis was performed in an ACL-TOP 700 autoanalyzer (Instrumentation Laboratory, Bedford, MA, USA).

This paper presents a zero-dimension model of a capillary plasma pulse jet generator governed by wall ablation feed of plasma. Experiments are made and electrical measurements compared with model simulations. Spectral measurements are performed to validate the assumption of radiation from black body radiation with a gray factor.

Plasma Wakefield Accelerators are based on the excitation of large amplitude plasma waves excited by either a laser or a particle driver beam. The amplitude of the waves, as well as their spatial dimensions and the consequent accelerating gradient depend strongly on the background electron density along the path of the accelerated particles. The process needs stable and reliable plasma sources, whose density profile must be controlled and properly engineered to ensure the appropriate accelerating mechanism. Plasma confinement inside gas filled capillaries have been studied in the past since this technique allows to control the evolution of the plasma, ensuring a stable and repeatable plasma density distribution during the interaction with the drivers. Moreover, in a gas filled capillary plasma can be pre-ionized by a current discharge to avoid ionization losses. Different capillary geometries have been studied to allow the proper temporal and spatial evolution of the plasma along the acceleration length. Results of this analysis obtained by varying the length and the number of gas inlets will be presented., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Objective The aim of this study was to develop, validate and apply a high performance liquid chromatography (HPLC) assay for analysis of paracetamol, paracetamol glucuronide and paracetamol sulfate in plasma (venous and capillary) and saliva to study paracetamol pharmacokinetics in healthy volunteers. Methods Samples were prepared using protein precipitation and analysed using reverse phase HPLC with UV detection. This assay was applied to venous and capillary plasma and saliva samples from 20 healthy volunteers after paracetamol 1 g four times daily for three days. Key findings The HPLC assay for paracetamol and its metabolites was found to be sensitive and selective in plasma and saliva samples over the range 0.05–50 mg/l with an inter- and intraday precision and accuracy within 11.2% and 11.1%, respectively. Mean recoveries for all analytes were > 88%. A study of paracetamol pharmacokinetics in healthy volunteers found close agreement between the sampling matrices for paracetamol and metabolites (metabolites were not detected in saliva). The value for area under the concentration–time curve over the 6 h dosing interval of venous plasma (45.3 ± 12.9 mg/l.h) was significantly higher than that observed for capillary plasma (33.8 ± 12.9 mg/l.h) or saliva (35.1 ± 9.4 mg/l.h; P > 0.01). Conclusions Capillary blood and saliva collection were found to be reliable sampling matrices for the evaluation of paracetamol pharmacokinetics, although paracetamol metabolites were not detected in saliva.

A gas-filled capillary plasma source for potential use in conjunction with laser wakefield acceleration is developed, and its discharge characteristics are presented here. In the capillary, helium or hydrogen gas (~150 torr in pressure) is injected, and a pulsed high voltage (~25 kV) is applied for electrical discharge and plasma production. The discharge properties of the helium and hydrogen gases are compared. The plasma densities inside the capillary hole are measured with a Mach-Zehnder interferometer and are obtained separately by a simple analysis using the diffusion equation and measured current profiles.

Capillary plasma electrode discharge (CPED), which we have used to obtain high electron density nonequilibrium plasma, is a novel concept to suppress the glow-to-arc transition by stabilizing the cathode fall region of the discharge. The characteristic properties of CPED configuration have been investigated and compared to the dielectric barrier discharge (DBD) structure. Breakdown voltages and - characteristics of the DBD and the CPED structures have been studied for various gas pressure of helium.

Based on a simple circuit model, the global properties of the electrical discharge in a capillary discharge system are investigated by analyzing the breakdown electron temperature in terms of the applied voltage. The electrical charge and current flowing through the capillary hole are calculated from a theoretical model and compared with experimental observations, providing valuable information pertaining to system inductance, discharge-plasma resistivity in terms of the applied voltage, the breakdown temperature of electrons, and the time-averaged plasma density. The response time of the electrical breakdown in the capillary hole is expressed in terms of the electron temperature and the applied voltage.

Wall ablation is a critical physical process in the capillary plasma generator for electrothermal-chemical (ETC) guns, and its characteristics directly determine the generator's performance. In this paper, three different ablation models for the capillary discharge are studied. First, based on a recently developed two-layer kinetic model that takes into account the structure of the sheath in the plasma-wall transition region, ablation characteristics of two typical materials used in the ETC gun plasma generator, polytetrafluoroethylene and polyethylene, are calculated. These data are required for magnetohydrodynamic (MHD) plasma modeling, and for analysis of the characteristics of different materials from the viewpoint of capillary material selection. Then, using discharge parameters of a typical ETC plasma generator working cycle, three widely used ablation models are compared and analyzed. These models are the two-layer kinetic model (model-K), a model based on the Langmuir law (model-L) and a simplified arc-wall interaction model (model-E). The time dependence of the ablation rate and total ablated mass are calculated with each method, and then the features of the different ablation models are discussed. It demonstrates that the model-K is the most reliable model in terms of predictions accuracy, while its computational efficiency is poorer when applied in MHD simulations compared with the model-E.

Capacitively coupled capillary Ar and He plasmas have been generated in a quartz tube with the inner/outer diameters of 1.0/3.0 mm at the RF (13.56 MHz) powers of 3-7 W using the externally attached parallel-plate electrodes. Plasma expansion along a tube axis was a maximum at a gas pressure of 10-20 kPa, in which Vpp was a minimum and so Paschen's minimum condition was satisfied. The capillary plasma was magnetized by a strong magnetic field of 0.4 T to sustain the plasma at a low pressure, since the plasma did not ignite at the gas pressure below 2-4 kPa. The optical emission spectrum analysis revealed that atomic excitation temperature increased with decreasing gas pressure. Furthermore, it was found that the metastable atoms play an important role in the plasma sustenance at a high gas pressure.

The characteristic properties of microscale capillary plasma electrode structures were experimentally investigated and compared to the dielectric barrier discharge (DBD) structure. The vacuum ultraviolet (VUV) emission from the capillary plasma electrode discharges (CPEDs) was more intense and more efficient than the one from the DBD. Based on VUV emission characteristics, it is confirmed that the CPED-based plasma display could be a possible candidate to find the breakthrough in the luminance and luminous efficiency of plasma display.

Objective To assess red blood cell velocity in finger nail-fold capillaries using video capillaroscopy in patients with SSc and other collagen diseases. Methods This study included 127 patients with SSc as well as patients with SLE (n = 33), DM/PM (n = 21), RA (n = 13) and APS (n = 12), and 20 healthy subjects. Red blood cell velocity was evaluated using frame-to-frame determination of the position of capillary plasma gaps. Results The mean red blood cell velocity was significantly decreased in patients with SSc compared to healthy controls (63.0% reduction) and patients with other conditions. Mean blood velocity was similar between patients with dcSSc and lcSSc. Importantly, even SSc patients with normal or non-specific nail-fold video capillaroscopic (NVC) patterns or a scleroderma early NVC pattern exhibited a significantly lower red blood cell velocity compared to healthy controls (51.7 and 61.4% reduction, respectively) or patients with other conditions, despite normal or mild capillary changes. Patients with the scleroderma active and late NVC pattern showed a more decreased blood velocity (65.5 and 66.2% reduction, respectively). This reduced blood velocity was significantly associated with NVC findings, including capillary ramification and capillary loss. Although remarkably reduced velocity was observed in SSc patients with intractable digital ulcers (72.1% reduction), it was significantly improved by lipo-prostaglandin E(1) (lipo-PGE(1)) infusion. Conclusion Our results suggest that reduced blood velocity is a hallmark of SSc. Furthermore, measurement of red blood cell velocity may be useful in evaluating therapeutic effects on microcirculation.

We report the generation of variable plasma densities up to 1019 cm-3 in hydrogen-filled hollow cathode capillary discharges and consider their applications as a practical plasma source for particle-beam-driven plasma wakefield accelerators. The capillary consists of a transparent cylindrical borosilicate glass tube. The plasma density is determined as a function of time, using Stark broadening of the Halpha line, with a resolution of 50 ns, and is found to decay exponentially with a typical time constant of several hundreds of nanoseconds. The time delay between the discharge and the drive electron beam can therefore be tuned to reach the density appropriate for the maximum acceleration gradient. The dependence of the plasma density on the capillary geometry and gas pressure is discussed, and the results of optical studies of the discharge channel formation process are presented. The implications of the results for beam-driven plasma accelerators araree discussed.

This work expands upon previous research into developing a numerical model of a capillary plasma source for application to electrothermal chemical guns. The capillary model is comprised of a kinetic model simulating polyethylene ablation coupled to a one dimensional time-dependent hydrodynamic model to determine the capillary outflow parameters. As input the simulation requires the capillary internal radius, length, and applied electrical current. Previous work found that best agreement with experimentally measured ablated mass could be achieved with the application of a backflux parameter, representing the percentage of the ablated material that was allowed to return to the polyethylene surface and form a film. Using the model, a parameter study is conducted to determine the effects that varying the peak electrical current, internal capillary radius and backflux parameter have on the plasma temperature, peak outflow pressure, and total ablated mass. A sinusoidal electrical current is assumed in the present work, with the peak current and discharge time taken over a range typically encountered in electrothermal chemical gun application. Analysis of the dependence of total ablated mass and peak capillary pressure on the deposited electrical energy yield insight into non- linearities in the capillary energy equation.

Electrothermal-chemical (ETC) propulsion with the control of a combustion process yet requires large electrical energies for an appreciable effect. Referring to the changed tendency of focusing ETC researches on the early ignition phase, the Agency for Defense Development (ADD), Korea, has been studying an electrothermal ignition for a 120-mm gun using a capillary plasma injector. Under the condition of a limited capillary geometry, design efforts with various liner materials have been done to achieve robust capillary discharges capable of transferring energies around 100 kJ. Electrical properties were estimated with the help of plasma theories and compared with experimental results. Experiments using a closed vessel and a gun-chamber simulator have been done to investigate the burning behaviors and the early phase of an electrothermal ignition, respectively. The closed vessel was designed for both a plasma and a conventional ignition. The burning rates could be obtained up to 70 MPa. The gun-chamber simulator was designed in the shape of the chamber of a 120-mm gun except for an acrylic chamber wall withstanding up to 30 MPa. Through prior tests using the closed vessel and the gun-chamber simulator, appropriate electrical energies and propellant have been selected. Firings of the full-scale 120-mm gun have been done using JA2 propellant. Electrical pulses of 1-2.5-ms duration in the energy from 20 to 120 kJ were applied. Aside from ignition capability, the results showed a possibility of a control on the peak pressure. Currently, ADD, Korea, continues the research to enhance the efficiency of the plasma injector, to compact the pulse forming network, and to investigate the electrothermal ignition properties of LOVA propellant.

Plasma density represents a very important parameter for both laser wakefield and plasma wakefield acceleration, which use a gas-filled capillary plasma source. Several techniques can be used to measure the plasma density within a capillary discharge, which are mainly based on optical diagnostic methods, as for example the well-known spectroscopic method using the Stark broadening effect. In this work, we introduce a preliminary study on an alternative way to detect the plasma density, based on the shock waves produced by gas discharge in a capillary. Firstly, the measurements of the acoustic spectral content relative to the laser-induced plasmas by a solid target allowed us to understand the main properties of the acoustic waves produced during this kind of plasma generation; afterwards, we have extended such acoustic technique to the capillary plasma source in order to calibrate it by comparison with the stark broadening method.

Objectives: To compare transcutaneous bilirubin measurements made using Bilicheck equipment with assays of capillary plasma using the Unistat bilirubinometer (Leica). Methods:Two hundred concomitant assays were performed (transcutaneous and in plasma), and the correlation and level of agreement between them was calculated. An assessment was also made of the influence of birth weight, skin color, gestational age, postnatal age and phototherapy. Results: The linear correlation coefficient was 0.92, and the mean difference between assays was 0.72 (±1.57) mg/dL, with a 95% confidence interval from -2.42 to +3.86. The best of a series of ROC curves demonstrated that transcutaneous assays at 14 mg/dL offer the best sensitivity (88.2%) and specificity (97.8%), with a positive predictive value of 78.9%, negative predictive value of 98.9 and are below the curve of 0.98. Conclusions: Assays performed using Bilicheck can be substituted for capillary plasma assays up to 14 mg/dL. Above this level the device should only be used for screening for patients whose bilirubin should be assayed in blood.

OBJETIVOS: Comparar dosagens transcutâneas de bilirrubina pelo Bilicheck com a dosagem plasmática capilar pelo bilirrubinômetro Unistat (Leica). MÉTODOS: Foram realizadas 200 dosagens concomitantes (transcutânea e plasmática), calculadas a correlação e concordância entre elas e feita avaliação da influência do peso de nascimento, raça, idade gestacional, idade pós-natal e uso de fototerapia. RESULTADOS: A correlação linear foi de 0,92, e a média da diferença entre as dosagens foi de 0,72 (±1,57) mg/dL, com intervalo de confiança em 95% de -2,42 a +3,86. A curva ROC realizada com a dosagem transcutânea em 14 mg/dL demonstrou melhor sensibilidade (88,2%) e especificidade (97,8%), com valor preditivo positivo de 78,9%, valor preditivo negativo de 98,9 e área abaixo da curva de 0,98. CONCLUSÃO: A dosagem realizada pelo Bilicheck pode substituir a dosagem plasmática capilar até o valor de 14 mg/dL. Acima deste nível, deve ser considerada apenas como rastreador na seleção de pacientes que devem ser submetidos a dosagem sangüínea. OBJECTIVES: To compare transcutaneous bilirubin measurements made using Bilicheck equipment with assays of capillary plasma using the Unistat bilirubinometer (Leica). METHODS: Two hundred concomitant assays were performed (transcutaneous and in plasma), and the correlation and level of agreement between them was calculated. An assessment was also made of the influence of birth weight, skin color, gestational age, postnatal age and phototherapy. RESULTS: The linear correlation coefficient was 0.92, and the mean difference between assays was 0.72 (±1.57) mg/dL, with a 95% confidence interval from -2.42 to +3.86. The best of a series of ROC curves demonstrated that transcutaneous assays at 14 mg/dL offer the best sensitivity (88.2%) and specificity (97.8%), with a positive predictive value of 78.9%, negative predictive value of 98.9 and are below the curve of 0.98. CONCLUSIONS: Assays performed using Bilicheck can be substituted for capillary plasma assays up to 14 mg/dL. Above this level the device should only be used for screening for patients whose bilirubin should be assayed in blood.

Electrothermal-chemical ignition systems have been demonstrated in gun systems to provide desirable characteristics including reproducible shorter ignition delays. We present a combined theoretical and experimental study of the capillary discharge with an aim to develop a capillary plasma source with efficient energy conversion. The major emphasis in the present capillary discharge model is the ablation phenomenon. Consideration is given to different characteristic subregions near the ablated surface: namely, a space-charge sheath, a Knudsen layer, and a hydrodynamic layer. A kinetic approach is used to determine the parameters at the interface between the kinetic Knudsen layer and the hydrodynamic layer. Coupling the solution of the nonequilibrium Knudsen layer with the hydrodynamic layer provides a self-consistent solution for the ablation rate. According to the model predictions, the peak electron temperature is about 1.4 eV, the polyethylene surface temperature is about 700 K, and the pressure is about 10 MPa in the case of a 0.6 kJ discharge. In parallel, a parametric experimental study of the capillary ablation process is conducted. The ablation rates are measured for capillary tubes made of polyethylene and Teflon. Both experimental measurements and simulations indicate that the ablated mass increases with the peak discharge current and that a smaller diameter capillary yields a larger ablated mass. It is found that model predictions agree well with experimental measurements

This paper presents the results of temporal measurements of the soft X-ray radiation intensity in the spectral range of 10-40 eV emitted from the capillary plasma under discharge with a current pulse of 26 kA amplitude and rising rate of about 1012 A/s. The experiments were carried out on a pulsed-power facility SIGNAL with ceramic capillaries of 0.3 cm inner diameter and 15.7 cm length, which are filled with argon up to pressures in the range of 0.25-0.5 torr. To interpret the experimental results, a sequence of numerical calculations simulating gas dynamics and level-by-level ionic kinetics of argon plasma was used. The effect of X-ray lasing in the Ne-like line was found to be generated with a quanta energy of 26.4 eV, which lasted for approximately 1-2 ns, at a moment of about 33 ns after the current pulse start

Pulsed plasma discharge in the interior region of electrothermal–chemical gun is numerically investigated with the one-dimensional time-dependent mathematical modeling that includes the Joule heating of plasma column and the mass ablation of bore wall. Sonic boundary condition is utilized because flow is expected to be choked at the bore exit. In the evaluation of thermodynamic and transport properties, plasma state is assumed to be in local thermal equilibrium due to high pressure and is found to be weakly nonideal. The computational results show that capillary plasma flow at the bore exit is partially ionized high temperature and high pressure discharge. Many predicted data including arc resistance, energy deposition, and bore wall mass ablation are favorably compared with the measurements on total 8 shots of gun firings with different levels of energy deposition ranging from 5.3 to 47 kJ. Temporal evolution of pressure shows transient effect in the calculations but the effect is minimal compared to the significant transient effect in the pressure measurements. However, maximum pressure is in good agreement with measured data.

We report the results of parametric and kinetic studies of the plasmochemical degradation of volatile organic compounds (VOCs) present in respirable atmospheres using a nonthermal ambient-pressure plasma generated in a pin-to-plate capillary plasma electrode (CPE) discharge reactor. Parameters studied included the reactor volume, contaminant residence time, energy density, and influent contaminant concentration. A kinetic model was developed based on a plug-flow regime and a second-order kinetic expression with respect to the reactive plasma species and contaminant concentration. Experimental data were fitted to the proposed model using nonlinear regression techniques, and plasmochemical degradation rate constants were determined for toluene, ethylbenzene, and m-xylene as model compounds.

The capillary plasma device is a relatively new technology for producing plasma vapor after ablating the capillary bore wall using high-magnitude pulsed electric power. Time-dependent behavior of the plasma flow in the capillary plasma device is investigated numerically by solving the radially averaged one-dimensional inviscid conservative equations of gas dynamics using LCPFCT gas dynamics code, which utilizes flux corrected transport (FCT) in solving generalized continuity equations. Joule heating and the mass ablation from the bore wall are incorporated in the numerical modeling. The thermodynamic and transport properties of the plasma are evaluated based on the assumption of local thermodynamic equilibrium and weakly nonideal plasma. At the bore exit, the sonic boundary condition is applied due to the thermally choked flow. The computational results yield the details of the plasma discharge behavior in the capillary bore including high-pressure and high-temperature plasma conditions at the bore exit. The plasma composition at the bore exit shows the significant ionization of the polycarbonate atomic species to the first ionization level, but the second ionization is found to be negligible. Computed mass ablation from the bore wall agrees well with the experimentally determined mass loss, but the assumption of blackbody radiation from the bulk plasma yields the overprediction in mass ablation.

It is important to understand the physical processes contributed by the plasma injector in the development of an electrothermal-chemical (ETC) gun. To investigate basic properties of a capillary discharge, an injector was discharged in open air. Comparing the measured and the calculated plasma resistivities, the state of power balance was investigated. The capillary plasma discharged in open air showed large ejection of plasma without power-balancing, while the capillary plasma produced in the ETC gun experiment reaches near balanced steady-state as the pressure of the combustion chamber becomes appreciable. The ejected flames were monitored with a high-speed camera. Typically the observed flames were about 50 cm /spl sim/1 m long and 25 cm wide. To estimate temperature and density, a preliminary measurement of time-resolved spectra in the visible wavelength region was done.

A new type of capillary with closing switch properties is proposed as a realistic alternative to the conventional capillary in electrothermal (ET) launchers. This capillary is designed as a plasma switch with a trigger electrode (TE) in place of an exploding wire. The capillary plasma switch (CPS) has dual functions of plasma generator or ignition for chemical medium, plus as a switch for the charged circuit, which considerably simplifies the power supply system and meets the requirements of a compact system. The conventional closing switches in the power system for ET launchers can be eliminated. In our work up to now, the special emphasis for CPS has been on the design of the TE. Experiments were carried out to investigate the electrical characteristics of CPS. This paper describes details of experimental testing of devices under a wide range of operating conditions and example waveforms are illustrated. The experiments proved that the CPS was suitable for ET launchers and can offer several advantages over the conventional capillary such as repetitive operation and compactness.

We report the results of experiments aimed at the investigation of the destruction of spore-forming bacteria, which are believed to be among the most resistant micro-organisms, using a novel atmospheric-pressure capillary plasma electrode discharge plasma. Various well-characterized cultures of Bacillus Subtilis were prepared, subjected to atmospheric-pressure plasma jets emanating from a plasma-shower reactor operated either in He or in air (N/sub 2//O/sub 2/ mixture) at various power levels and exposure times, and analyzed after plasma treatment. Reductions in colony-forming units ranged from 10/sup 4/ (He plasma) to 10/sup 8/ (air plasma) for plasma exposure times of less than 10 min.

Background and objective: A mini volume loading test (mVLT) was proposed for estimating hydration status and interstitial fluid accumulation during stepwise infusion of crystalloids. The method is based on both the transcapillary reflux model and the hypothesis that when subjects are dehydrated, venous plasma dilution induced by a fluid challenge is higher than in the capillaries, and that difference is diminished when the fluid challenge is given to more hydrated individuals. Our objective was to test that hypothesis by evaluating the veno-capillary dilution difference during mVLT in subjects with different hydration status. Materials and methods: In a prospective randomized crossover study, three mini fluid challenges were given to 12 healthy volunteers on two occasions. The subjects were either dehydrated or hydrated before the experiments. Results: In dehydrated subjects only, capillary plasma dilution was significantly lower than venous (P = 0.015, 0.005 and 0.006) after each mini fluid challenge. Conclusions: Veno-capillary dilution difference during mVLT depends on the hydration status. The mVLT method could possibly discriminate between the different states of hydration.