Angiogenic Effects and Crosstalk of Adipose-Derived Mesenchymal Stem/Stromal Cells and Their Extracellular Vesicles with Endothelial Cells

Adipose-derived mesenchymal stem/stromal cells (ASCs) are an adult stem cell population able to self-renew and differentiate into numerous cell lineages. ASCs provide a promising future for therapeutic angiogenesis due to their ability to promote blood vessel formation. Specifically, their ability to differentiate into endothelial cells (ECs) and pericyte-like cells and to secrete angiogenesis-promoting growth factors and extracellular vesicles (EVs) makes them an ideal option in cell therapy and in regenerative medicine in conditions including tissue ischemia. In recent angiogenesis research, ASCs have often been co-cultured with an endothelial cell (EC) type in order to form mature vessel-like networks in specific culture conditions. In this review, we introduce co-culture systems and co-transplantation studies between ASCs and ECs. In co-cultures, the cells communicate via direct cell–cell contact or via paracrine signaling. Most often, ASCs are found in the perivascular niche lining the vessels, where they stabilize the vascular structures and express common pericyte surface proteins. In co-cultures, ASCs modulate endothelial cells and induce angiogenesis by promoting tube formation, partly via secretion of EVs. In vivo co-transplantation of ASCs and ECs showed improved formation of functional vessels over a single cell type transplantation. Adipose tissue as a cell source for both mesenchymal stem cells and ECs for co-transplantation serves as a prominent option for therapeutic angiogenesis and blood perfusion in vivo.     

Asymmetric versus symmetric pulses for cortical microstimulation

Intracortical microstimulation (ICMS), which has shown promise in the visual, auditory and somatosensory systems as a platform for sensory prostheses, typically relies on charged balanced, symmetric, biphasic stimulation. However, neural stimulation models as well as experiments conducted in cochlear implant users have suggested that charge balanced asymmetric pulses could generate lower detection thresholds for stimulation in terms of charge per phase. For this study, rats were chronically implanted with microelectrode arrays unilaterally in their right auditory cortex and then trained to detect ICMS delivered through a single electrode site in order to determine their behavioral threshold. This model was used in two experiments. The first experiment addressed the effect of lead phase direction, asymmetry, and phase duration on detection threshold. The second experiment fixed the cathode phase duration at 123 μs and varied only the phase asymmetry and lead phase direction. Taken together, the results of these experiments suggest that, for ICMS, the primary determinant of threshold level is cathode phase duration, and that asymmetry provides no significant advantage when compared to symmetric, cathode leading pulses. However, symmetric anode leading pulses of less than or equal to 205 μs per phase consistently showed higher thresholds when compared to all other pulses of equal cathode phase duration.     

Intrinsic and extrinsic mechanisms of vortex formation in superfluid3He-B

We report on the first comprehensive measurements of critical superflow velocities in³He-B which allow different mechanisms of vortex formation to be identified. As a function of temperatureT and pressureP, we measure the critical angular velocity Ω_c(T, P) at which vortices start to form in slowly accelerating rotation in a cylindrical container filled with³He-B. Owing to the long coherence length ξ(T, P)∼10–100 nm, either trapped remanent vorticity or intrinsic nucleation may dominate vortex formation, depending on the roughness of the container wall and the presence of loaded traps. NMR measurement with a resolution of one single vortex line allows us to distinguish between different processes: (1) Three extrinsic mechanisms of vortex formation have been observed. One of them is the vortex mill, a continuous periodic source which is activated in a rough-walled container well below the limit for intrinsic nucleation. (2) In a closed smooth-walled container intrinsic nucleation is the only mechanism available, with a critical velocity v_c(T, P)=Ω_c(T, P), whereR is the radius of the container. We findv _c (T, P) to be related to the calculated intrinsic stability limitv _ch (T, P) of homogeneous superflow. The existence of this connection in the form of a scaling law implies that nucleation takes place at an instability, rather than by thermal activation or quantum tunneling which become impossible because of an inaccessibly high energy barrier.     

A computational technique for the design of a specific optimal controller

For a linear plant, the optimization of a performance index of integral type, which is quadratic in states and control, results in a control law. This ideal controller, however, must often be replaced by an approximate controller; e.g., due to inaccessible state variables. The input-output relation of such a controller may be specified within some parameters in advance. A specific optimal controller (SOC) is obtained when the parameters are chosen in an optimal manner so as to minimize a performance criterion; for example, the degradation of a performance index. Since these parameters depend on the initial state, the SOC is designed in regard to the worst initial state resulting in the maximum deterioration, which is then minimized by the best parameters. A computational procedure for this design is proposed. An algorithm is constructed and applied to this min-max problem.     

3He NMR with a 100 μm Planar Nb Coil

A superconducting 100 m planar coil has been tested for low field cw NMR. The nine-turn 5 nH coil is connected via a planar 1:8 step-up transformer to an external parallel capacitor and resonated at 0.8 MHz to give a Q of 350. The tank circuit voltage is measured with a liquid He temperature GaAs MESFET preamplifier. Test experiments have been conducted by immersing the Si chip with the planar pick-up coil in liquid and solid ³ He to measure their cw NMR absorptions in the temperature range 0.05 – 0.5 K.     

Modeling of ferric sulfate decomposition and sulfation of potassium chloride during grate‐firing of biomass

Ferric sulfate is used as an additive in biomass combustion to convert the released potassium chloride to the less harmful potassium sulfate. The decomposition of ferric sulfate is studied in a fast heating rate thermogravimetric analyzer and a volumetric reaction model is proposed to describe the process. The yields of sulfur oxides from ferric sulfate decomposition under boiler conditions are investigated experimentally, revealing a distribution of approximately 40% SO₃ and 60% SO₂. The ferric sulfate decomposition model is combined with a detailed kinetic model of gas‐phase KCl sulfation and a model of K₂SO₄ condensation to simulate the sulfation of KCl by ferric sulfate addition. The simulation results show good agreements with experiments conducted in a biomass grate‐firing reactor. The results indicate that the SO₃ released from ferric sulfate decomposition is the main contributor to KCl sulfation and that the effectiveness of ferric sulfate addition is sensitive to the applied temperature conditions. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4314–4324, 2013     

Bromine as an ash forming element in a fluidised bed boiler combusting solid recovered fuel

Plastic materials are the main sources of chlorine in solid recovered fuels (SRF). Chlorine is attributed to be the main initiator of slagging, fouling and corrosion in biomass and waste combustion as it lowers the melting point of ash forming matter and reacts chemically with the heat transfer surface steels. SRF may also contain sources of bromine in the form of brominated flame retardants (BFRs) applied in many plastics and textiles. Results presented in this paper from an experimental campaign at an 80 MW_th bubbling fluidised bed (BFB) boiler show that bromine is behaving in a similar manner as chlorine: bromine was found at the corrosion front in boiler membrane wall tubes, and as water soluble salts in aerosol samples collected from the furnace and electrostatic precipitator (ESP) ash. It is evident from these results and the data in the literature that most of the salts of bromine are, by both their fate and physical and chemical properties, similar to those of chlorine. It can be concluded that it if there is a source of bromine in the fuel corrosive high vapour pressure bromides can be formed analogously to chlorides.