Diagnosis on atmospheric pressure plasma jets

In der vorliegenden Arbeit werden zwei Atmosphärendruck-Plasmajets untersucht, die einen hohen Leistungsumsatz von mehreren hundert Watt haben. Zur Prozessoptimierung müssen die Eigenschaften dieser Plasmen und ihre Wechselwirkungen mit Oberflächen bekannt sein. In dieser Arbeit werden die Abhängigkeiten verschiedener Plasmaeigenschaften und Oberflächenwechselwirkungen von den Prozess- und Anlagenparametern identifiziert. Dabei werden die diagnostischen Möglichkeiten zur Untersuchung solcher Atmosphärendruck-Plasmajets durch Anpassung des Designs und der Auswertemethodik um passive kalorimetrische Sonden erweitert. Zum ersten Mal wird zudem das Laserabsorptionsspektroskopie- Systems Q-MACS erfolgreich zur Konzentrationsbestimmung im Effluenten eingesetzt. Außerdem werden optische Emissionsspektroskopie, dynamische Untersuchungen mit einer phasenaufgelösten Kamera und Schichtuntersuchungen durch Rasterelektronenmikroskopie und energiedispersive Röntgenspektroskopie durchgeführt. Die Abhängigkeiten der betrachteten Plasmaeigenschaften und Oberflächenwechselwirkungen von den Parametern werden gezeigt. Die Untersuchungen zeigen unter anderem, dass die Wahl des Düsenkopfes der Plasmajets einen entscheidenden Einfluss auf die Zusammensetzung des Effluenten, den Energieeinstrom und insbesondere dessen Abhängigkeit vom Prozessgasfluss hat. Die Untersuchungen der behandelten Oberflächen ergeben, dass durch den Einsatz des Präkursors Acetylen aus Nanopartikeln zusammengesetzte amorphe Kohlenwasserstoffschichten gebildet werden.Within the present work two atmospheric pressure plasma jets, which exhibit a high power conversion of several hundred watts, are investigated. In order to optimize processes the characteristics of these plasmas and their interactions with surfaces have to be known. Within this work, the dependences of different characteristics and surface interactions on the process and system parameters are identified. At the same time, the diagnostic possibilities for the investigation on this kind of atmospheric pressure plasma jet are extended by passive calorimetric probes through changes in probe design and analysis. For the first time, the laser absorption spectroscopy system Q-MACS is used to measure concentrations in the effluent. Moreover, optical emission spectroscopy, dynamical studies with a phase resolved camera and coating examinations with scanning electron microscopy and energy dispersive X-ray spectroscopy are conducted. The dependences of the examined properties and surface interactions on the parameters are shown. The investigations show, amongst other things, that the choice of the nozzle head of the plasma jets has a significant influence on the composition of the effluent, the energy influx and, in particular, its dependence on the process gas flow. The investigations of treated surfaces reveal that the use of the precursor acetylene yields in the formation of amorphous hydrocarbon coatings composed of nanoparticles

A representação do movimento no português paulista

The aim of this article is to analyze how motion can be organized and represented in Paulista Portuguese (Portuguese spoken in São Paulo), in data taken from several genres of text from the 18th to the 20th centuries. I take into account the patterns proposed by Talmy (2000b), and the representation of path points in motion events. The analysis is qualitative and quantitative, taking into account the discursive properties of the texts in the corpora, based on the Discourse Traditions model.Este trabalho tem como objetivo analisar de que maneira o movimento pode ser organizado e representado no Português Paulista em corpora dos séculos XVIII a XX. Para tanto, analiso os padrões de combinação propostos por Talmy (2000b) e a representação dospontos do percurso num deslocamento no espaço físico. A análise é qualitativa e quantitativa, e nesse caso, levei em conta as propriedades discursivas dos textos que compõem os corpora, à luz do modelo de Tradições Discursivas

Redobramento, recursão e verbos de movimento em português

Neste artigo apresento um dos padrões de representação do movimento em português, especificamente quando há redobramento da informação do percurso no verbo e em expressões preposicionadas ou adverbiais. Para tanto, retomo o conceito de redobramento sintático apresentado por Moraes de Castilho (2005, 2011), atrelado ao Princípio de Recursão da Abordagem Multissistêmica (CASTILHO 2015). Com base na Semântica Cognitiva, mais especificamente na proposta de Talmy (1985, 2000b), descrevo dados do português arcaico com alguns verbos de movimento (entrar, sair, subir etc.) em que se observa o redobramento da informação de percurso. Ao final, coloco algumas questões e encaminhamentos para pesquisas futuras

Effect of a Spatially Fluctuating Heating of Particles in a Plasma Spray Process

The work is concerned with the effect of a spatially fluctuating heating of Al2O3 particles with diameters of 5–120 μm during a plasma spray process. A plasma jet is generated in a mixture of Ar (40 NLPM) and H2 (14 NLPM) and in pure Ar at an electric current of 600 A. The tracing of the injected particles in the plume region of the plasma jets is considered in the framework of a three-dimensional model taking into account a turbulent fluid flow. It is shown that the heat source for the injected particles exhibits a well pronounced spatially fluctuating structure due to the enhancement of the thermal conductivity resulting from dissociation and ionization of the molecular gas in the temperature range of 2500–4000 K and 13,000–14,000 K, respectively. During their travel towards the substrate, the particles are therefore repeatedly heated in the gas mixture in contrast to the case of pure argon. Particles injected in the gas mixture reach the substrate with a higher average temperature and velocity

Self-Consistent Cathode–Plasma Coupling and Role of the Fluid Flow Approach in Torch Modeling

A two-dimensional and stationary magnetohydrodynamic model of a plasma spray torch operated with argon is developed to predict the plasma properties in a steady operating mode. The model couples a submodel of a refractory cathode and its non-equilibrium boundary layer to a submodel of the plasma in local thermodynamic equilibrium in a self-consistent manner. The Navier–Stokes equations for a laminar and compressible flow are solved in terms of low and high Mach number numerical approaches. The results show that the Mach number can reach values close to one. Simulations are performed for electric currents of 600 A and 800 A, and gas flow rates of 40, 60, and 80 NLPM. The plasma parameters obtained by the two approaches differ, and the differences become more pronounced for higher currents and gas flow rates. The arc voltage, the electric power, and the thermal efficiency from both the low and high Mach number models of the plasma agree well with experimental findings for a current of 600 A and a flow rate of 40 NLPM. For higher currents and gas flow rates, the results of the low and high Mach number models gradually differ and underline the greater appropriateness of the high Mach number model

Modelling and experimental evidence of the cathode erosion in a plasma spray torch

The lifetime of tungsten cathodes used in plasma spray torches is limited by processes leading to a loss of cathode material. It was reported in the literature that the mechanism of their erosion is the evaporation. A model of the ionization layer of a cathode is developed to study the diffusive transport of evaporated tungsten atoms and tungsten ions produced due to ionization by electron impact in a background argon plasma. It is shown that the Stefan-Maxwell equations do not reduce to Fick law as one could expect for the transport of diluted species, which is due to significant diffusion velocities of argon ions. The ionization of tungsten atoms occurs in a distance of a few micrometers from the cathode surface and leads to a strong sink, which increases the net flux of tungsten atoms far beyond that obtained in absence of tungsten ions. This shows that the tungsten ions are driven by the electric field towards the cathode resulting in no net diffusive flux and no removal of tungsten species from the ionization layer even if convection is accounted for. A possible mechanism of removal is found by extending the model to comprise an anode. The extended model resolves the inter-electrode region and provides the plasma parameters for a current density corresponding to the value at the center of the cathode under typical arc currents of 600 A and 800 A. The presence of the anode causes a reversal of the electric field on the anode side, which pulls the ions away from the ionization layer of the cathode. The net flux of tungsten ions can be further fortified by convection. This model allows one to evaluate the loss of cathode material under realistic operating conditions in a quantitative agreement with measured values

Modelling and experimental evidence of the cathode erosion in a plasma spray torch

The lifetime of tungsten cathodes used in plasma spray torches is limited by processes leading to a loss of cathode material. It was reported in the literature that the mechanism of their erosion is the evaporation. A model of the ionization layer of a cathode is developed to study the diffusive transport of evaporated tungsten atoms and tungsten ions produced due to ionization by electron impact in a background argon plasma. It is shown that the Stefan–Maxwell equations do not reduce to Fick law as one could expect for the transport of diluted species, which is due to significant diffusion velocities of argon ions. The ionization of tungsten atoms occurs in a distance of a few micrometers from the cathode surface and leads to a strong sink, which increases the net flux of tungsten atoms far beyond that obtained in absence of tungsten ions. This shows that the tungsten ions are driven by the electric field towards the cathode resulting in no net diffusive flux and no removal of tungsten species from the ionization layer even if convection is accounted for. A possible mechanism of removal is found by extending the model to comprise an anode. The extended model resolves the inter-electrode region and provides the plasma parameters for a current density corresponding to the value at the center of the cathode under typical arc currents of 600 A and 800 A. The presence of the anode causes a reversal of the electric field on the anode side, which pulls the ions away from the ionization layer of the cathode. The net flux of tungsten ions can be further fortified by convection. This model allows one to evaluate the loss of cathode material under realistic operating conditions in a quantitative agreement with measured values.info:eu-repo/semantics/publishedVersio

Energy Flux Characterisation of Atmospheric Pressure Plasma Spray Torches with Passive Thermal Probes

Passive thermal probes were applied on two different plasma spraying devices to gain a detailed understanding of the energy flux towards the substrate under atmospheric pressure. The challenge of very high thermal load was solved by using an advanced time-resolved measuring and evaluation technique. The combination with a controlled movement of the jets allowed to obtain insightful radial profiles. The energy flux to the substrate changes linearly to the electrical input power. When adding diatomic gases (H2/N2) to the gas mixture the energy flux increases significantly, suggesting a more efficient energy transport. For increasing the axial distance, the energy flux shows a quadratic reduction. The obtained radial profiles are exemplarily utilized to show the inhomogeneous effect of powder injection on the energy flux distribution

A Phase I Dose Escalation Study of the Triple Angiokinase Inhibitor Nintedanib Combined with Low-Dose Cytarabine in Elderly Patients with Acute Myeloid Leukemia

Nintedanib (BIBF 1120), a potent multikinase inhibitor of VEGFR-1/-2/-3, FGFR-1/-2/-3 and PDGFR-α/-β, exerts growth inhibitory and pro-apoptotic effects in myeloid leukemic cells, especially when used in combination with cytarabine. This phase I study evaluated nintedanib in combination with low-dose cytarabine (LDAC) in elderly patients with untreated or relapsed/refractory acute myeloid leukemia (AML) ineligible for intensive chemotherapy in a 3+3 design. Nintedanib (dose levels 100, 150, and 200 mg orally twice daily) and LDAC (20 mg subcutaneous injection twice daily for 10 days) were administered in 28-day cycles. Dose-limiting toxicity (DLT) was defined as non-hematological severe adverse reaction CTC grade ≥ 4 with possible or definite relationship to nintedanib. Between April 2012 and October 2013, 13 patients (median age 73 [range: 62–86] years) were enrolled. One patient did not receive study medication and was replaced. Nine (69%) patients had relapsed or refractory disease and 6 (46%) patients had unfavorable cytogenetics. The most frequently reported treatment-related adverse events (AE) were gastrointestinal events. Twelve SAEs irrespective of relatedness were reported. Two SUSARs were observed, one fatal hypercalcemia and one fatal gastrointestinal infection. Two patients (17%) with relapsed AML achieved a complete remission (one CR, one CRi) and bone marrow blast reductions without fulfilling PR criteria were observed in 3 patients (25%). One-year overall survival was 33%. Nintedanib combined with LDAC shows an adequate safety profile and survival data are promising in a difficult-to-treat patient population. Continuation of this trial with a phase II recommended dose of 2 x 200 mg nintedanib in a randomized, placebo-controlled phase II study is planned. The trial is registered to EudraCT as 2011-001086-41