Secondary Plasma Research Articles

Methods of calibrating standard plasma radiators using an electron synchrotron with an intense magnetic field

Methods of calibrating secondary standard plasma radiators, based on the use of a synchrotron with an intense magnetic field, are developed, which enable problems of both vacuum coupling of the acceleration chamber and the plasma radiator to be solved, and also enable the degree of polarization of the synchronous radiation to be taken into account. It is shown that a comparison of the characteristics of the synchrotron radiation of the storage ring and of the electron synchrotron in the visible region using a telescope and cooled CCD matrix ensures that the relative synchrotron spectrum is absolute.

The expression pattern of small nucleolar and small Cajal body-specific RNAs characterizes distinct molecular subtypes of multiple myeloma

Small nucleolar RNAs (snoRNAs) and small Cajal body-specific RNAs (scaRNAs) are non-coding RNAs involved in the maturation of other RNA molecules and generally located in the introns of host genes. It is now emerging that altered sno/scaRNAs expression may have a pathological role in cancer. This study elucidates the patterns of sno/scaRNAs expression in multiple myeloma (MM) by profiling purified malignant plasma cells from 55 MMs, 8 secondary plasma cell leukemias (sPCLs) and 4 normal controls. Overall, a global sno/scaRNAs downregulation was found in MMs and, even more, in sPCLs compared with normal plasma cells. Whereas SCARNA22 resulted the only sno/scaRNA characterizing the translocation/cyclin D4 (TC4) MM, TC2 group displayed a distinct sno/scaRNA signature overexpressing members of SNORD115 and SNORD116 families located in a region finely regulated by an imprinting center at 15q11, which, however, resulted overall hypomethylated in MMs independently of the SNORD115 and SNORD116 expression levels. Finally, integrative analyses with available gene expression and genome-wide data revealed the occurrence of significant sno/scaRNAs/host genes co-expression and the putative influence of allelic imbalances on specific snoRNAs expression. Our data extend the current view of sno/scaRNAs deregulation in cancer and add novel information to the bio-molecular complexity of plasma cell dyscrasias.

The blood chemical status of Atlantic cod Gadus morhua following capture by jig and demersal longline with differential hook removal methods

Common haematological [haematocrit (Hct)], primary (serum cortisol) and secondary (serum glucose and plasma lactate) analytes were utilized to compare blood biochemical status of Gadus morhua captured rapidly by jig with that of G. morhua captured by commercial demersal longline. In general, the physiological status of G. morhua, despite blind hook times, was significantly more disrupted (pronounced haemo-concentration and significantly elevated concentrations of cortisol, glucose and lactate) following longline capture relative to capture by jig, while no differences were detected among longline-caught fish as a function of dehooking method (or concomitant extent of overt physical trauma). Blood profiles from the more stressed G. morhua, a possible function of more extended longline hook times, were similar to the most stressed values reported for this species. The results also demonstrate that, although acute blood biochemical status is an effective gauge of relative stress, it does not reflect physical injury status, which has been shown to exert a strong influence on delayed mortality in previous studies in this species. Thus, acute blood chemical status alone may not be the most complete predictor of mortality. Future studies should evaluate physiological repercussions from capture-handling against physical trauma during more extended post-release periods for this species.

Microstructure and photocatalytic activity of APS coatings obtained from different TIO2 nanopowders

In recent years, intense research has shown that thermal spray techniques, especially atmospheric plasma spraying (APS), can be used to obtain nanostructured TiO2 coatings with effective photocatalytic activity.This study compares the photocatalytic activity of APS coatings obtained from different powders: two nanostructured TiO2 powders produced by spray-drying of two TiO2 nanosuspensions with different solids contents, one spray-dried powder obtained from a suspension comprising a mixture of submicronic and nanometric TiO2 particles and finally one commercial, nanostructured, TiO2 spray-dried powder. All powders were characterised by XRD, FEG-ESEM, granule size distribution, and a flowability evaluation. Feedstock powders were then deposited on austenitic stainless steel coupons using APS. Hydrogen or helium was used as secondary plasma gas. Coating microstructure and phase composition were characterised using FEG-ESEM and XRD techniques; coating anatase content was quantified by the Rietveld method.A significant amount of anatase to rutile transformation was found to take place during the plasma spraying process. In general, the coatings had a bimodal microstructure characterised by the presence of completely fused areas in addition to non-molten areas consisting of agglomerates of anatase nanoparticles. Results also showed that anatase content and porosity of the coatings largely depend on the secondary plasma gas nature, as well as on the characteristics of the feedstock.Finally the photocatalytic activity of the coatings was determined by measuring the degradation of methylene blue dye in an aqueous solution. A reasonably good fit of a first-order kinetic model to the experimental data was found for all coatings. The values of the kinetic constant were related to feedstock characteristics as well as to plasma spraying conditions.

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Aim Genomic alterations and somatic mutations have been widely identified in hematologic malignancies. Recent studies have described mutations in different HLA genes of these patients. These mutations are identified when high resolution typing is needed for patients and potential donors. An African American patient treated for myeloma, received an autologous stem cell transplant in 2010. During 2011 he was diagnosed with a secondary plasma cell leukemia, becoming a candidate for an allogeneic stem cell transplant. Methods HR HLA typing was performed by Sequence Based Typing (SBT) methodology and a single base mismatch on one of his HLA-DQB1 allele was identified in exon 2, codon 13, leading to an amino acid substitution (Glycine to Valine). Three siblings, considered potential donors, had HLA typing performed and the same HLA-DQB1 ∗ 06:XX was identified in two of them. To investigate the HLA-DQB1 novel allele segregation and its origin within the family, their mother was typed. Results One of the HLA-DQB1 alleles identified did not match with DQB1 alleles from HLA database 3.6.0, used for the SBT data analysis. Their mother HLA typing identified HLA-DQB1∗06:02:01 and DQB1 ∗ 06:XX. The alleles DQB1 ∗ 06:XX and DQB1 ∗ 06:02:01 differ by 1 nucleotide mismatch in exon 2, which caused us to question what genetic alterations that may have occurred in her DQB1 genes. Conclusions Our findings demonstrate that the hematological malignancy is not always the cause for HLA genes alterations, which reinforces the value of family studies to explain gene segregation. Beyond the implications of obtaining an accurate HLA typing and donor selection, these genetic alterations on HLA genes may allow some mechanisms of immune surveillance to fail when associated with other complications caused by hematological malignancies affecting bone marrow transplant candidates. The allele in question was also identified by another HLA laboratory, and is included in the most recent IMGT HLA alleles update, it was named HLA-DQB1 ∗ 06:49.

Whole-genome sequencing of multiple myeloma from diagnosis to plasma cell leukemia reveals genomic initiating events, evolution, and clonal tides

AbstractThe longitudinal evolution of a myeloma genome from diagnosis to plasma cell leukemia has not previously been reported. We used whole-genome sequencing (WGS) on 4 purified tumor samples and patient germline DNA drawn over a 5-year period in a t(4;14) multiple myeloma patient. Tumor samples were acquired at diagnosis, first relapse, second relapse, and end-stage secondary plasma cell leukemia (sPCL). In addition to the t(4;14), all tumor time points also shared 10 common single-nucleotide variants (SNVs) on WGS comprising shared initiating events. Interestingly, we observed genomic sequence variants that waxed and waned with time in progressive tumors, suggesting the presence of multiple independent, yet related, clones at diagnosis that rose and fell in dominance. Five newly acquired SNVs, including truncating mutations of RB1 and ZKSCAN3, were observed only in the final sPCL sample suggesting leukemic transformation events. This longitudinal WGS characterization of the natural history of a high-risk myeloma patient demonstrated tumor heterogeneity at diagnosis with shifting dominance of tumor clones over time and has also identified potential mutations contributing to myelomagenesis as well as transformation from myeloma to overt extramedullary disease such as sPCL.

THE VERY HIGH ENERGY EMISSION FROM PULSARS: A CASE FOR INVERSE COMPTON SCATTERING

The observations of gamma-ray emission from pulsars with the Fermi-LAT detector and the detection of the Crab pulsar with the VERITAS array of Cherenkov telescopes at energies above 100 GeV make it unlikely that curvature radiation is the main source of photons above GeV energies in the Crab and many other pulsars. We outline a model in which the broad UV-X-ray component and the very high energy \gamma-ray emission of pulsars are explained within the Synchrotron-Self-Compton (SSC) framework. We argue that the bulk of the observed radiation is generated by the secondary plasma, which is produced in cascades in the outer gaps of the magnetosphere. We find that the inverse-Compton (IC) scattering occurs in the Klein-Nishina regime, which favors synchrotron photons in the UV band as target field for the scattering process. The primary beam is accelerated in a modest electric field, with a field strength that is of the order of a few percent of the magnetic field near the light cylinder. Overall, in the Klein-Nishina regime of the IC scattering the particle distribution in the gap does not evolve towards a stationary distribution and thus is intrinsically time-dependent. We point out that in a radiation reaction-limited regime of particle acceleration the gamma-ray luminosity L_{\gamma} scales linearly with the pulsar spin-down power \dot{E}, L_\gamma ~ \dot{E}, and not proportional to \sqrt{\dot{E}} as expected from potential-limited acceleration.

Time-Resolved Spectroscopy of Electrostatic Discharge and Secondary Arc Plasma on Spacecraft Solar Array

Primary electrostatic discharges (ESD) and secondary arcs on spacecraft solar panels are simulated experimentally by introducing a needle trigger and investigated with a time-resolved emission spectroscopy method. The total spectral domain investigated ranges from 220 to 750 nm. An innovative active method has been developed in order to initiate ESD at a controllable time and location on triple-junction solar cells. It permits one to detect important steps of the discharge evolution, in particular the transition between primary ESDs and secondary arcs. In this experimental setup, the discharge begins on the triple-junction solar cell absorber, with gallium and germanium being detected from the very beginning. That indicates that the obtained ESDs are triggered on the solar cell edge close to the cover glass. The transition between primary ESDs and secondary arcs is accompanied by molecular material vaporization. It is thought that the glue or the underlying polyimide is evaporated mainly during secondary arcs, sometimes during primary ESDs. Once the secondary arcing is triggered, the complete edge of the solar cell assembly is impacted. That confirms that ESDs may significantly damage the solar cell assemblies.

Efficacy of bortezomib, lenalidomide and dexamethasone (VRD) in secondary plasma cell leukaemia

Efficacy of bortezomib, lenalidomide and dexamethasone (VRD) in secondary plasma cell leukaemia

Genome-Based Reconstruction of the Protein Import Machinery in the Secondary Plastid of a Chlorarachniophyte Alga

Most plastid proteins are encoded by their nuclear genomes and need to be targeted across multiple envelope membranes. In vascular plants, the translocons at the outer and inner envelope membranes of chloroplasts (TOC and TIC, respectively) facilitate transport across the two plastid membranes. In contrast, several algal groups harbor more complex plastids, the so-called secondary plastids, which are surrounded by three or four membranes, but the plastid protein import machinery (in particular, how proteins cross the membrane corresponding to the secondary endosymbiont plasma membrane) remains unexplored in many of these algae. To reconstruct the putative protein import machinery of a secondary plastid, we used the chlorarachniophyte alga Bigelowiella natans, whose plastid is bounded by four membranes and still possesses a relict nucleus of a green algal endosymbiont (the nucleomorph) in the intermembrane space. We identified nine homologs of plant-like TOC/TIC components in the recently sequenced B. natans nuclear genome, adding to the two that remain in the nucleomorph genome (B. natans TOC75 [BnTOC75] and BnTIC20). All of these proteins were predicted to be localized to the plastid and might function in the inner two membranes. We also show that the homologs of a protein, Der1, that is known to mediate transport across the second membrane in the several lineages with secondary plastids of red algal origin is not associated with plastid protein targeting in B. natans. How plastid proteins cross this membrane remains a mystery, but it is clear that the protein transport machinery of chlorarachniophyte plastids differs from that of red algal secondary plastids.

Model for a transformer-coupled toroidal plasma source

A two-dimensional fluid plasma model for a transformer-coupled toroidal plasma source is described. Ferrites are used in this device to improve the electromagnetic coupling between the primary coils carrying radio frequency (rf) current and a secondary plasma loop. Appropriate components of the Maxwell equations are solved to determine the electromagnetic fields and electron power deposition in the model. The effect of gas flow on species transport is also considered. The model is applied to 1 Torr Ar/NH3 plasma in this article. Rf electric field lines form a loop in the vacuum chamber and generate a plasma ring. Due to rapid dissociation of NH3, NHx+ ions are more prevalent near the gas inlet and Ar+ ions are the dominant ions farther downstream. NH3 and its by-products rapidly dissociate into small fragments as the gas flows through the plasma. With increasing source power, NH3 dissociates more readily and NHx+ ions are more tightly confined near the gas inlet. Gas flow rate significantly influences the plasma characteristics. With increasing gas flow rate, NH3 dissociation occurs farther from the gas inlet in regions with higher electron density. Consequently, more NH4+ ions are produced and dissociation by-products have higher concentrations near the outlet.

Broad beam sources of fast molecules with segmented cold cathodes and emissive grids

Experimental study of fast neutral atom and molecule beam sources with rectangular and circular cross-section of the beam up to 0.8 m2 is carried out and the study results are presented. The fast particles are produced as a result of charge exchange collisions between gas molecules and ions accelerated by potential drop between the plasma emitter of the beam source and the secondary plasma inside the processing vacuum chamber. As the emitter is used a glow discharge plasma, whose electrons are confined in an electrostatic trap formed by a cold hollow cathode and an emissive grid, which is negative both to the cathode and to the chamber. In order to prevent from breakdowns between the emitter and the cathode at a current in the cathode circuit up to 10 A as well as between the emitter and the grid at a voltage between them up to 10 kV the cathode and the grid are composed of isolated from each other segments, which are connected to power supplies through resistors. When resistance of the resistorR > U/I0, where U is the power supply voltage and I0 is the minimal current of stable vacuum arc for a given segment material, then transition from the glow discharge to the steady-state vacuum arc is totally excluded in spite of numerous breakdowns of microsecond duration due to contamination of the source electrodes during its operation with dielectric films and other stimulants of the arc.

Structural Control of Carbon Nickel Thin Films Without Substrate Heating

ABSTRACTA variety of characterization techniques have been employed to study the growth and structure of nickel carbon thin films fabricated by ionized magnetron sputter deposition. A two target magnetron system is used along with an RF powered coil, to create a secondary plasma, with a DC bias applied at the substrate. By varying the bias it is possible to control the energy of the depositing species as well as a range of other plasma properties and therefore the resulting film microstructure. It has been observed that a change from the metastable hexagonal nickel carbide phase to the stable face centered cubic structure of nickel can be induced. This change in metal crystallinity was accompanied by a change in carbon ordering. The ability to control the film structure and morphology without the need for substrate heating opens up the possibility of depositing a range of structures onto polymers.

Wave and transport studies utilizing dense plasma filaments generated with a lanthanum hexaboride cathode

A portable lanthanum hexaboride (LaB6) cathode has been developed for use in the LArge Plasma Device (LAPD) at UCLA. The LaB6 cathode can be used as a tool for many different studies in experimental plasma physics. To date, the cathode has been used as a source of a plasma with a hot dense core for transport studies and diagnostics development, as a source of gradient driven modes, as a source of shear Alfvén waves, and as a source of interacting current channels in reconnection experiments. The LaB6 cathode is capable of higher discharge current densities than the main barium oxide coated LAPD cathode and is therefore able to produce plasmas of higher densities and higher electron temperatures. The 8.25 cm diameter cathode can be introduced into the LAPD at different axial locations without the need to break vacuum. The cathode can be scaled up or down for use as a portable secondary plasma source in other machines.

Two-Dimensional LCIF Images of Electron Density and Temperature Within an ECR Plasma Cathode

Two-dimensional mappings of electron density and temperature within an electron cyclotron resonance (ECR) plasma cathode are presented. As electron current is extracted, a secondary plasma is formed on the upstream side of the extraction aperture, and the spatial distribution of the ECR plasma is affected. The aperture plasma is surrounded by a region of “hot” electrons, suggesting the possibility of a double layer near the aperture.

Plasma Plume Ignited by Plasma Plume at Atmospheric Pressure

In this paper, a plasma jet device is used to study the propagation of plasma plumes at atmospheric pressure. It is found that a primary plasma plume can ignite a secondary plasma plume, which can further ignite a tertiary plasma plume. Each plume is separated from another by a single tube. High-speed photographs show that the secondary plasma plume is ignited after the primary plasma plume is extinguished. Likewise, the tertiary plasma plume is ignited after the secondary plasma plume disappears.

Absorption of gamma-ray photons in a vacuum neutron star magnetosphere: II. The formation of “lightnings”

The absorption of a high-energy photon from the external cosmic gamma-ray background in the inner neutron star magnetosphere triggers the generation of a secondary electron-positron plasma and gives rise to a lightning - a lengthening and simultaneously expanding plasma tube. It propagates along magnetic fields lines with a velocity close to the speed of light. The high electron-positron plasma generation rate leads to dynamical screening of the longitudinal electric field that is provided not by charge separation but by electric current growth in the lightning. The lightning radius is comparable to the polar cap radius of a radio pulsar. The number of electron-positron pairs produced in the lightning in its lifetime reaches 10^28. The density of the forming plasma is comparable to or even higher than that in the polar cap regions of ordinary pulsars. This suggests that the radio emission from individual lightnings can be observed. Since the formation time of the radio emission is limited by the lightning lifetime, the possible single short radio bursts may be associated with rotating radio transients (RRATs).

Value assignment of the WHO 6th International Standard for blood coagulation factor VIII and von Willebrand factor in plasma (07/316).

Value assignment of the WHO 6th International Standard for blood coagulation factor VIII and von Willebrand factor in plasma (07/316).

Influence of the Configuration of the Plasma Chamber on the Surface Modification of Synthetic Vulcanized Rubber Treated with Low‐pressure Oxygen RF Plasma

AbstractThree different configurations of RF low‐pressure oxygen plasmas were used to modify the surface of vulcanized styrene–butadiene rubber. Direct, etching and downstream oxygen plasma treatments of the rubber were carried out for length of treatment between 1 and 10 min. The oxygen plasma treated rubber surfaces were characterized by ethylene glycol contact angle measurements, ATR‐IR and XPS spectroscopy and scanning electron microscopy (SEM). Adhesion of the oxygen plasma treated rubber to polyurethane adhesive was carried out by means of T‐peel test and the loci of failure of the joints were characterized by means of ATR‐IR spectroscopy. Three different oxygen plasma configurations obtained by changing the position of the rubber sample in the plasma chamber and by changing the shelves (power, ground, floating) were used to modify the extent of surface modification and the temperature reached on rubber surface. The direct oxygen plasma was the most aggressive treatment and the secondary downstream plasma the less one. The increase in the length of the oxygen plasma treatment allowed the most efficient removal of antiozonant paraffin wax from the as‐received rubber. Furthermore, the oxygen plasma treatments created CO moieties on the rubber surface. On the other hand, only 1 min treatment time was sufficient to decrease noticeably the contact angle value on the rubber surface, irrespective of the oxygen plasma chamber configuration and the length of treatment. Oxygen plasma treatment caused surface oxidation and ablation on the rubber surface, as well as an increase of the temperature that also determined the extent of paraffin wax migration, the migration was favoured for temperature higher than 45 °C. Finally, the migration of paraffin wax was produced for at least 24 h after oxygen plasma treatment and poor adhesion to polyurethane adhesive was obtained, due to the creation of a weak boundary layer of paraffin wax at the rubber–polyurethane interface. The migration of paraffin wax caused during plasma treatment was the dominant factor in decreasing the adhesion of rubber to polyurethane adhesive.magnified image

Modelling and Simulation of the Advanced Plasma Source

Plasma ion assisted-deposition (PIAD) is a combination of conventional thermal evaporation deposition and plasma-beam surface modification; it serves as a well-established technology for the creation of high quality coatings on mirrors, lenses, and other optical devices. It is closely related to ion-assisted deposition to the extent that electrons preserve quasineutrality of the ion beam. This paper investigates the Advanced Plasma Source (APS), a plasma beam source employed for PIAD. A field enhanced glow discharge generates a radially expanding plasma flow with an ion energy of about 80-120 eV. Charge exchange collisions with the neutral background gas (pressure 0.1 Pa and below) produce a cold secondary plasma, which expands as well. A model is developed which describes the primary ions by a simplified Boltzmann equation, the secondary ions by the equations of continuity and momentum balance, and the electrons by the condition of Boltzmann equilibrium. Additionally, quasineutrality is assumed. The model can be reduced to a single nonlinear differential equation for the velocity of the secondary ions, which has several removable singularities and one essential singularity, identified as the Bohm singularity. Solving the model yields macroscopic plasma features, such as fluxes, densities, and the electrical field. An add-on Monte-Carlo simulation is employed to calculate the ion energy distribution function at the substrate. All results compare well to experiments conducted at a commercial APS system.