An experimental and numerical study of flames in narrow channels with electric fields

The proceeding at: 14th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS 2014). Took at 2014, November, 18-21, in Awaji Island, Hyogo Japan. The event Web site in: http://powermems2014.org/The advancement of microscale combustion has been limited by quenching effects as flames cease to be much smaller than combustors. The long studied sensitivity of flames to electrical effects may provide means to overcome this issue. Here we experimentally and numerically investigate the potential of electric field effects to enhance combustion. The results demonstrate that, under specific conditions, externally electric fields will sustain combustion in structures smaller than the quenching distance. The analysis proposes a reduced mechanism to model this result and provides a study of the governing parameters. We find good qualitative agreement between the model and experiments. Specifically, the model is found to successfully capture the capacity to increase and decrease flame speed according to electric field magnitude and direction. Further, in both experiments and computations the sensitivity to electrical enhancement increases for more energetic mixtures. We do find that the model underpredicts the maximum achievable speed enhancement observed, suggesting that additional phenomena should be included to expand the range of conditions that can be studied.Publicad

The role of non-thermal electrons in flame acceleration

We examine in this work the effect of an external electric field on the propagation velocity of a laminar, one-dimensional and lean premixed flame, with the final goal of clarifying the relative importance of each of the three different mechanisms postulated in the literature to explain the effect of electric fields on flames: ionic wind, kinetic enhancement by non-thermal electrons and ohmic heating. The onedimensional model proposed here expands the four-reactions scheme previously presented by SanchezSanz, et al. (2015) to include the effect of non-thermal electrons and activated neutral molecules on flame acceleration. Two additional reactions are included in the model to complete a minimum set of six elementary reaction capable of qualitatively reproduce the results observed in classical Uaggers, and Von Engel, (1971).) and recent (Volkov et al., 2013; Murphy, et al., 2014,) experiments. The limit of weakly ionized plasmas is used to integrate the Boltzmann equation and to derive an explicit expression for the electron temperature proportional to the square of the electric field. The numerical integration of the conservation equations gives the flame propagation velocity for a given set of parameters. The results reveal the importance of the electric field polarity on flame acceleration, finding faster flames for positive electric fields than for equally intense negative fields. At low-intensity fields, our results indicate that the ionic wind, and the associated redistribution of the charged particles, is the main mechanism inducing flame acceleration. In more intense fields, the combined effect of the ionic wind and the heat transfer from the high-temperature electrons to the background gas induces a significant increase in the temperature field upstream and downstream of the flame front.This work was supported by the Spanish MCINN through projects ENE2012-33213 and ENE2015-65852-C2-1-R

Effect of an external electric field on the propagation velocity of premixed flames

There have been many experimental investigations into the ability of electric fields to enhance combustion by acting upon ion species present in flames. In this work, we examine this phenomenon using a one-dimensional model of a lean premixed flame under the influence of a longitudinal electric field. We expand upon prior two-step chain-branching reaction laminar models with reactions to model the creation and consumption of both a positively-charged radical species and free electrons. Also included are the electromotive force in the conservation equation for ion species and the electrostatic form of the Maxwell equations in order to resolve ion transport by externally applied and internally induced electric fields. The numerical solution of these equations allows us to compute changes in flame speed due to electric fields. Further, the variation of key kinetic and transport parameters modifies the electrical sensitivity of the flame. From changes in flame speed and reactant profiles we are able to gain novel, valuable insight into how and why combustion can be controlled by electric fields.This collaborative research was supported by the Spanish MCINN under Project #ENE2012–33213 and by King Abdullah University of Science and Technology (KAUST), Cooperative Agreement # 025478 entitled, electromagnetically Enhanced Combustion: Electric Flames.Publicad

Observaciones sobre algunos Narcissus L. del occidente de la Península Ibérica

Se dan noticias de tres híbridos en el género Narcissus L. presentes en las montañas del oeste de la P. Ibérica: N. × trevejensis Patino, Urrutia & Valencia, N. × brevitubulosus A. Fern. nothosubsp. jalamensis Patino, Urrutia & Valencia y N. × brevitubulosus A. Fern. nothosubsp. sanabrensis Patino, Urrutia & Valencia. Se realiza una nueva combinación y se propone una síntesis del tratamiento nomenclatural de este último híbrido

Platelet-Rich Plasma for Injured Peripheral Nerves: Biological Repair Process and Clinical Application Guidelines

Platelet-rich plasma (PRP) is a biological therapy that uses the patient’s own blood to obtain products with a higher platelet concentration than in blood. It provides a transient fibrin scaffold as a controlled drug delivery system of growth factors suitable for regenerative medicine. PRP has been used as medical strategy to treat diverse types of injuries in the field of orthopedics, including peripheral nerve lesions. In vitro and in vivo studies showed the neuroprotective, neurogenic and neuroinflammatory modulator effect of PRP. In addition, it has been demonstrated clinically that PRP infiltrations improve clinical symptoms and enhance the sensory and motor functional nerve muscle unit recovery. Potential effects of PRP could be applied in treatments for neuropathies, as conservative treatment by means of nerve ultrasound-guided infiltrations or as biological adjuvant during surgery

PRP Injections in Orthopaedic Surgery: Why, When and How to Use PRP Dynamic Liquid Scaffold Injections in Orthopaedic Surgery

Platelet-rich plasma (PRP) products can be described as any autologous blood platelet concentrate within a plasma suspension. PRP products include plasma and twofold or greater increases in platelet concentrations above baseline levels. The injection of activated PRP in its liquid formulation delivers growth factors locally and simultaneously mimics and amplifies the spontaneous healing response in injured areas and in special cell niches, which would otherwise be inaccessible. This in situ generated transient three-dimensional scaffold will gradually release growth factors and maintain their concentration at the site of the scaffold formation. The combination of liquid PRP with surgical techniques in orthopaedic surgery allows a wide range of therapeutic strategies in the management of injuries in the field of orthopaedics and sports medicine. The use of different therapeutic elements, including PRP as biological stimuli and rehabilitation and physiotherapy treatments as mechanical stimuli, provides extremely favourable synergies that will help fulfil the physician’s objective, to stop the progression of disease and to improve function in the shortest period of tim

Dos nuevos narcisos híbridos en el occidente de la península ibérica

Narcissus ×villasrubiensis González, Patino, Solís & Urrutia [N. triandrus L. subsp. pallidulus (Graells)] Rivas Goday × N. vitekii P. Escobar] and Narcissus × galaicus González, Patino, Solís & Urrutia (N. cyclamineus DC. × N. triandrus L. subsp. triandrus) are described

Nitric Oxide prevents aortic neointimal hyperplasia by controlling macrophage polarization.

Objective— Nitric oxide synthase 3 (NOS3) prevents neointima hyperplasia by still unknown mechanisms. To demonstrate the significance of endothelial nitric oxide in the polarization of infiltrated macrophages through the expression of matrix metalloproteinase (MMP)-13 in neointima formation. Approach and Results— After aortic endothelial denudation, NOS3 null mice show elevated neointima formation, detecting increased mobilization of LSK (lineage-negative [Lin]-stem-cell antigen 1 [SCA1]+KIT+) progenitor cells, and high ratios of M1 (proinflammatory) to M2 (resolving) macrophages, accompanied by high expression of interleukin-5, interleukin-6, MCP-1 (monocyte chemoattractant protein), VEGF (vascular endothelial growth factor), GM-CSF (granulocyte-macrophage colony stimulating factor), interleukin-1β, and interferon-γ. In conditional c-Myc knockout mice, in which M2 polarization is defective, denuded aortas showed extensive wall thickening as well. Conditioned medium from NOS3-deficient endothelium induced extensive repolarization of M2 macrophages to an M1 phenotype, and vascular smooth muscle cells proliferated and migrated faster in conditioned medium from M1 macrophages. Among the different proteins participating in cell migration, MMP-13 was preferentially expressed by M1 macrophages. M1-mediated vascular smooth muscle cell migration was inhibited when macrophages were isolated from MMP-13–deficient mice, whereas exogenous administration of MMP-13 to vascular smooth muscle cell fully restored migration. Excess vessel wall thickening in mice lacking NOS3 was partially reversed by simultaneous deletion of MMP-13, indicating that NOS3 prevents neointimal hyperplasia by preventing MMP-13 activity. An excess of M1-polarized macrophages that coexpress MMP-13 was also detected in human carotid samples from endarterectomized patients. Conclusions— These findings indicate that at least M1 macrophage-mediated expression of MMP-13 in NOS3 null mice induces neointima formation after vascular injury, suggesting that MMP-13 may represent a new promising target in vascular disease.pre-print262 K

Narcissus × andujarensis, una especie híbrida nueva

T: A new nothoespecies N. × andujarensis Hervás, Patino, Solis & Urrutia (N. bulbocodium subsp. bulbocodium × N. fernandesii) is described