Analysis of the plasma transport in numerical simulations of helicon plasma thrusters

The accurate simulation of the plasma transport in helicon sources is a key aspect to improve the design of Helicon Plasma Thrusters (HPTs). Specifically, the 3D-VIRTUS code was proven to provide satisfactory estimations of the propulsive performance of realistic HPTs (difference between measures and numerical estimations of the thrust <30%). Nonetheless, further investigations are needed to deepen the influence that the plasma chemistry model, the formulation of the energy equation, and the definition of the diffusion coefficients have on the results of the simulation. First, a quantitative analysis has been conducted on a simplified configuration of HPT to study each phenomenon separately. Second, the generalized fluid model has been benchmarked against measures of plasma density performed on a helicon source. The radiative decay reactions affect the estimation of the performance (e.g., thrust) up to 40%. The quasi-isotherm formulation of the energy equation affects results (e.g., electron density) up to 30%. Accounting for anomalous transport or defining diffusion coefficients classically does not have a major effect on the simulation (e.g., thrust varies less than 20%). The generalized formulation of the fluid model provides estimations of the plasma density, which are within the uncertainty band of the measures (i.e., differences <20%)

Development of a Global Model for the Analysis of Plasma in an Atmosphere-Breathing Cathode-Less Thruster

This study investigates the preliminary propulsive performances of a cathode-less plasma thruster with air as its propellant. The analysis is carried out through a global model and simulates a thruster over a power range of 0 to 50 W. The developed code considers a set of 177 chemical reactions involving 8 different species and includes empirical equations to account for electronegative effects. The analysis presents the steady-state values of species densities at 10 W, 30 W, and 50 W to gain insights into the key characteristics of plasma dynamics. Moreover, the study estimates the thrust and specific impulse and compares the results to data from models that employ xenon and iodine, aiming to understand the performances of air in low-power thrusters. Lastly, the study examines the effects of varying air inflow concentration on the chemistry, analyzing three different orbit altitudes (i.e., 200, 300, and 400 km)

IDEAL REDUCTION OF CALORIES FOR GREATEST REDUCTION OF BODY FAT AND MAINTENANCE OF LEAN BODY MASS

Objectives: This retrospective clinical study was intended to assess the ideal number of calories in the Mediterranean-style diet (MD) required for maximum weight reduction through a greater decrease in fat mass (FM) and maintenance of fat-free mass (FFM). Methods: We analysed the data of 90 non-smoking subjects (56 females, age = 32.5 ± 9.6 years, BMI = 28.3 ± 5.4 kg/m2, data as mean ± SD). The participants underwent two-month individualised MDs with similar macronutrient composition (55% carbohydrate, 30% fat, 15% protein and fibre > 30 g) but different amounts of energy, which varied daily from 374 kcal to 1305 kcal compared with the total energy expenditure measured by metabolic Holter. The sample was divided into nine groups of 10 subjects in order to establish the amount of energy restriction that was most effective in terms of achieving fat loss and maintaining muscle mass. Results: All subject groups had significant improvements in body composition parameters (weight loss = 2.7 ± 1.8 kg, FM loss = 2.2 ± 1.2 kg and FFM loss = 0.5 ± 1.3 kg). Differences between the nine groups were not significant but higher FM loss was observed in groups one, three, six and eight. Groups one and four had the highest FFM increase and groups two, three and eight had the highest FFM loss. Conclusions: These data suggest that increasing the amount of energy restriction in a low-calorie MD might be useless in terms of obtaining a higher FM loss but a lower restriction could be more effective for maintaining FFM

Triplet vs doublet lenalidomide-containing regimens for the treatment of elderly patients with newly diagnosed multiple myeloma

Lenalidomide-dexamethasone improved outcome in newly diagnosed elderly multiple myeloma patients. We randomly assigned 662 patients who were age \u202165 years or transplantation-ineligible to receive induction with melphalan-prednisone-lenalidomide (MPR) or cyclophosphamide-prednisone-lenalidomide (CPR) or lenalidomide plus lowdose dexamethasone (Rd). The primary end point was progression-free survival (PFS) in triplet (MPR and CPR) vs doublet (Rd) lenalidomide-containing regimens. After a median follow-up of 39 months, the medianPFSwas22 months for the triplet combinations and 21 months for the doublet (P 5 .284). The median overall survival (OS) was not reached in either arms, and the 4-year OS was 67% for the triplet and 58% for the doublet arms (P 5 .709). By considering the 3 treatment arms separately, no difference in outcome was detected among MPR, CPR, and Rd. The most common grade \u20213 toxicity was neutropenia: 64% in MPR, 29% in CPR, and 25% in Rd patients (P < .0001). Grade \u20213 nonhematologic toxicities were similar among arms and were mainly infections (6.5% to 11%), constitutional (3.5% to 9.5%), and cardiac (4.5% to 6%), with no difference among the arms. In conclusion, in the overall population, the alkylator-containing tripletsMPRandCPRwere not superior to the alkylator-free doublet Rd, which was associated with lower toxicit

Blockade of interleukin-6 signalling with siltuximab enhances melphalan cytotoxicity in preclinical models of multiple myeloma

Signalling through the interleukin (IL)-6 pathway induces proliferation and drug resistance of multiple myeloma cells. We therefore sought to determine whether the IL-6-neutralizing monoclonal antibody siltuximab, formerly CNTO 328, could enhance the activity of melphalan, and to examine some of the mechanisms underlying this interaction. Siltuximab increased the cytotoxicity of melphalan in KAS-6/1, INA-6, ANBL-6, and RPMI 8226 human myeloma cell lines (HMCLs) in an additive-to-synergistic manner, and sensitized resistant RPMI 8226.LR5 cells to melphalan. These anti-proliferative effects were accompanied by enhanced activation of drug-specific apoptosis in HMCLs grown in suspension, and in HMCLs co-cultured with a human-derived stromal cell line. Siltuximab with melphalan enhanced activation of caspase-8, caspase-9, and the downstream effector caspase-3 compared with either of the single agents. This increased induction of cell death occurred in association with enhanced Bak activation. Neutralization of IL-6 also suppressed signalling through the phosphoinositide 3-kinase/Akt pathway, as evidenced by decreased phosphorylation of Akt, p70 S6 kinase and 4E-BP1. Importantly, the siltuximab/melphalan regimen demonstrated enhanced anti-proliferative effects against primary plasma cells derived from patients with myeloma, monoclonal gammopathy of undetermined significance, and amyloidosis. These studies provide a rationale for translation of siltuximab into the clinic in combination with melphalan-based therapies

Inductive Plasma Thruster (IPT) design for an Atmosphere-Breathing Electric Propulsion System (ABEP)

Challenging space missions include those at very low altitudes, where the atmosphere is source of aerodynamic drag on the spacecraft, therefore an efficient propulsion system is required to extend the mission lifetime. One solution is Atmosphere-Breathing Electric Propulsion (ABEP). It collects atmospheric particles to use as propellant for an electric thruster. This would minimize the requirement of limited propellant availability. The system could be applied to any planet with atmosphere, enabling new mission at these altitude ranges for continuous orbiting. Challenging is also the presence of reactive chemical species, such as atomic oxygen in Earth orbit. Such components are erosion source of (not only) propulsion system components, i.e. acceleration grids, electrodes, and discharge channels of conventional EP systems (RIT and HET). IRS is developing within the DISCOVERER project an intake and a thruster for an ABEP system. This paper deals with the design and first operation of the inductive plasma thruster (IPT) developed at IRS. The paper describes its design aided by numerical tools such as HELIC and ADAMANT. Such a device is based on RF electrodeless discharge aided by externally applied static magnetic field. The IPT is composed by a movable injector, to variate the discharge channel length, and a movable electromagnet to variate position and intensity of the magnetic field. By changing these parameters along with a novel antenna design for electric propulsion, the aim is to achieve the highest efficiency for the ionization stage by enabling the formation of helicon-based discharge. Finally, the designed IPT is presented and the feature of the birdcage antenna highlighted