Study of a single line of sight gamma ray diagnostics for measurements of the absolute gamma ray emission from JET

The fusion power produced in a DT thermonuclear reactor is currently determined by measuring the absolute 14 MeV neutron yield of the D(T, α)n fusion reaction. Measurements of 17 MeV gamma rays born from the much less probable D(T, 5He)γ reaction (branching ratio of ∼10−5) have been proposed as an alternative independent method to validate the neutron counting method and also to fulfill the requests of the nuclear regulator for licensing ITER DT operations. However, the development of absolute 17 MeV gamma ray emission measurements entails a number of requirements, such as: (i) knowledge of the 17 MeV gamma ray to 14 MeV neutron emission branching ratio; (ii) the simulation of the gamma ray transport from the extended plasma source to the gamma ray detectors; (iii) a careful determination of the absolute efficiency of previously calibrated gamma ray spectrometers. In this work, we have studied the possibility to infer the global gamma ray emission rate from measurements made with a 3″ × 6″ LaBr3 spectrometer installed at the end of a collimated tangential line of sight at the JET tokamak and using the neutron emission from deuterium plasmas of the most recent experimental campaigns. Results show that 17 MeV gamma ray fluxes at the end of this tangential line of sight have a weak dependence (less than 5%) on the plasma profile and can therefore be used to infer the total emission from the plasma.

Reteplase Fc-fusions produced in N. benthamiana are able to dissolve blood clots ex vivo

Thrombolytic and fibrinolytic therapies are effective treatments to dissolve blood clots in stroke therapy. Thrombolytic drugs activate plasminogen to its cleaved form plasmin, a proteolytic enzyme that breaks the crosslinks between fibrin molecules. The FDA-approved human tissue plasminogen activator Reteplase (rPA) is a non-glycosylated protein produced in E. coli. rPA is a deletion mutant of the wild-type Alteplase that benefits from an extended plasma half-life, reduced fibrin specificity and the ability to better penetrate into blood clots. Different methods have been proposed to improve the production of rPA. Here we show for the first time the transient expression in Nicotiana benthamiana of rPA fused to the immunoglobulin fragment crystallizable (Fc) domain on an IgG1, a strategy commonly used to improve the stability of therapeutic proteins. Despite our success on the expression and purification of dimeric rPA-Fc fusions, protein instability results in high amounts of Fc-derived degradation products. We hypothesize that the “Y”- shape of dimeric Fc fusions cause steric hindrance between protein domains and leads to physical instability. Indeed, mutations of critical residues in the Fc dimerization interface allowed the expression of fully stable rPA monomeric Fc-fusions. The ability of rPA-Fc to convert plasminogen into plasmin was demonstrated by plasminogen zymography and clot lysis assay shows that rPA-Fc is able to dissolve blood clots ex vivo. Finally, we addressed concerns with the plant-specific glycosylation by modulating rPA-Fc glycosylation towards serum-like structures including α2,6-sialylated and α1,6-core fucosylated N-glycans completely devoid of plant core fucose and xylose residues.

Effect of Laser Radiation on the Dynamics of Active Brownian Macroparticles in an Extended Plasma-Dust Monolayer

Using the modified method of Brownian dynamics, the dynamics of macroparticles with a uniform metal coating in a plasma-dust monolayer under the action of laser radiation was simulated. The time dependences of the root-mean-square and average linear displacements of particles were calculated for different initial effective parameters of nonideality and different intensities of laser radiation. A relationship was established that connects the effective parameter of nonideality of the dusty plasma system of active particles with the maximum value of the mean linear displacement of particles.

An Effective and Safe Enkephalin Analog for Antinociception

Opioids account for 69,000 overdose deaths per annum worldwide and cause serious side effects. Safer analgesics are urgently needed. The endogenous opioid peptide Leu-Enkephalin (Leu-ENK) is ineffective when introduced peripherally due to poor stability and limited membrane permeability. We developed a focused library of Leu-ENK analogs containing small hydrophobic modifications. N-pivaloyl analog KK-103 showed the highest binding affinity to the delta opioid receptor (68% relative to Leu-ENK) and an extended plasma half-life of 37 h. In the murine hot-plate model, subcutaneous KK-103 showed 10-fold improved anticonception (142%MPE·h) compared to Leu-ENK (14%MPE·h). In the formalin model, KK-103 reduced the licking and biting time to ~50% relative to the vehicle group. KK-103 was shown to act through the opioid receptors in the central nervous system. In contrast to morphine, KK-103 was longer-lasting and did not induce breathing depression, physical dependence, and tolerance, showing potential as a safe and effective analgesic.

Subcriticality control elements in a reactor system with an extended plasma source of neutrons with regard for temperature

Materials have been selected for the shim rods and burnable absorbers to compensate for the excessive reactivity of the facility’s blanket part and to provide for the possibility of reactivity control in conjunction with a plasma source of neutrons. Burnable absorber is a layer of zirconium diboride (ZrB2) with a thickness of 100 μm applied to the surface of fuel compacts. Boron carbide (B4C) rods installed in the helium flow channels and used to bring the entire system into a state with keff = 0.95 have been selected as the shim rod material. Throughout its operating cycle, the facility is subcritical and is controlled using the neutron flux from the plasma source. Verified codes, WIMS-D5B (ENDF/B-VII.0) and MCU5TPU (MCUDВ50), as well as a modern system of constants were used for the calculations. The facility’s neutronic performance was simulated with regard for the changes in the inner structure and temperature of the microencapsulated fuel and fuel compact materials caused by long-term irradiation and by the migration of fission fragments and gaseous chemical compounds.

A Linear Microwave Plasma Source Using a Circular Waveguide Filled with a Relatively High-Permittivity Dielectric: Comparison with a Conventional Quasi-Coaxial Line Waveguide

For a conventional linear microwave plasma source (LMPS) with a quasi-coaxial line transverse electromagnetic (TEM) waveguide, a linearly extended plasma is sustained by the surface wave outside the tube. Due to the characteristics of the quasi-coaxial line MPS, it is easy to generate a uniform plasma with radially omnidirectional surfaces, but it is difficult to maximize the electron density in a curved selected region. For the purpose of concentrating the plasma density in the deposition area, a novel LMPS which is suitable for curved structure deposition has been developed and compared with the conventional LMPS. As the shape of a circular waveguide, it is filled with relatively high-permittivity dielectric instead of a quasi-coaxial line waveguide. Microwave power at 2.45 GHz is transferred to the plasma through the continuous cylindrical-slotted line antenna, and the radiated electric field in the radial direction is made almost parallel to the tangential plane of the window surface. This research includes the advanced 3D numerical analysis and compares the results with the experiment. It shows that the electron density in the deposition area is higher than that of the conventional quasi-coaxial line plasma MPS.

Hybrid “Fusion-Fission” Reactor Facility on Thorium Fuel with a Source of Additional Thermonuclear Neutrons

The results of full-scale numerical experiments of a hybrid thorium-containing fuel cell facility operating in a close-to-critical state due to a controlled source of fusion neutrons are discussed in this work. The facility under study was a complex consisting of two blocks. The first block was based on the concept of a high-temperature gas-cooled thorium reactor core. The second block was an axially symmetrical extended plasma generator of additional neutrons that was placed in the near-axial zone of the facility blanket. The calculated models of the blanket and the plasma generator of D-T neutrons created within the work allowed for research of the neutronic parameters of the facility in stationary and pulse-periodic operation modes. This research will make it possible to construct a safe facility and investigate the properties of thorium fuel, which can be continuously used in the epithermal spectrum of the considered hybrid fusion-fission reactor.

Imaging spectropolarimetry for magnetic field diagnostics in solar prominences

Context. Narrowband imaging spectropolarimetry is one of the most powerful tools available to infer information about the intensity and topology of the magnetic fields present in extended plasma structures in the solar atmosphere. Aims. We describe the instrumental set-up and the observing procedure that we have developed and optimized at the Istituto Ricerche Solari Locarno in order to perform imaging spectropolarimetry. A measurement that highlights the potential of the ensuing observations for magnetic field diagnostics in solar prominences is presented. Methods. Monochromatic images of solar prominences were obtained by combining a tunable narrowband filter, based on two Fabry-Perot etalons, with a Czerny-Turner spectrograph. Linear and circular polarization were measured at every pixel of the monochromatic image with the Zurich Imaging Polarimeter, ZIMPOL. A wavelength scan was performed across the profile of the considered spectral line. The HAZEL inversion code was applied to the observed Stokes profiles to infer a series of physical properties of the observed structure. Results. We carried out a spectropolarimetric observation of a prominence, consisting of a set of quasi-monochromatic images across the He I D3 line at 5876 Å in the four Stokes parameters. The map of observed Stokes profiles was inverted with HAZEL, finding magnetic fields with intensities between 15 and 30 G and directed along the spine of the prominence, which is in agreement with the results of previous works.