Satellite Propellant Pump Research

NASA Glenn initiated a satellite propellant pump technology demonstration program. The goal was to demonstrate the technologies for a 60 percent efficient pump at 1 gpm flow rate and 500 psia pressure rise. The pump design and analysis used the in-house developed computer codes named PUMPA and HPUMP3D. The requirements lead to a 4-stage impeller type pump design with a tip diameter of 0.54 inches and a rotational speed of 57,000 rpm. Analyses indicated that flow cavitation was not a problem in the design. Since the flow was incompressible, the stages were identical. Only the 2-stage pump was designed, fabricated, assembled, and tested for demonstration. Water was selected as the surrogate fluid for hydrazine in this program. Complete mechanical design including stress and dynamic analyses were conducted. The pump was driven by an electric motor directly coupled to the impellers. Runs up to 57,000 rpm were conducted, where a pressure rise of 200 psia at a flow rate of 0.8 gpm was measured to validate the design effort

Heteropterys sericea

Angiosperm

Active Remembering, Selective Forgetting, and Collective Identity: The Case of Bloody Sunday

Bloody Sunday. Derry, Northern Ireland, January 30, 1972, in which 13 Catholic civilians were shot dead by the British army has evoked two contesting memories - an 'official' or elite memory and a folk memory among the Nationalist community that, it is argued, has been omitted from dominant memory discourses. The official memory of this life- destroying historical event is encoded in the report of the Widgery Tribunal established by the British government in the aftermath of bloody Sunday. A second popular memory has emerged in resistance to this that carries the remembrances of the victims'families and of the wider Nationalist community in Northern Ireland. I explore the mediums through which this unofficial memory has been established and maintained, the meanings associated with it, and how and why these have changed over time. Traditionally, it has been invested with a negative meaning associated with sectarianism, colonialism, and victimization. In recent times, the folk memory has been framed within a broader global context with a focus on its healing and reconciliation potential, which, together with institutional statements such as the Dowling Street Declaration and the Good Friday Agreement, points to the emergence of a more inclusivist understanding of collective identity-formation in Northern Ireland

Aproximation of continuous media models for granular systems using cellular automata

In this paper a new cellular automata model suitable for granular systems simulation is presented. The proposed model is shown to be equivalent to a particularization of the well known BCRE model of granular systems and a correspondence between the parameters of the presented model and the BCRE model is also set, allowing to fit these parameters for a given system. The model has the advantage over other cellular automata models of being more realistic in the behavior of the surface of heaps and slopes. The dynamics of the CA is analyzed in order to confirm that it also has one of the most important features of these systems, 1/f noise

Comparison of adipose particle size on autologous fat graft retention in a rodent model

Aim: Unpredictable retention outcomes remain a significant issue in autologous fat grafting procedures. Liposuction cannula variation leads to variability in fat particle size. Recent data suggest that the size of fat particles is closely related to graft healing outcomes; however, this remains a point of contention due to potential confounding variables such as tissue trauma with harvest. The aim of this study was to compare autologous fat grafting outcomes with variable fat particle sizes in an animal model which isolated fat particle size as the primary experimental variable. The overall goal of this work was to determine if reducing fat particle size is an effective method for enhancing graft retention in autologous fat grafting.Methods: The range of fat particle diameter harvested by four common liposuction cannulas was quantified to define relevant small and large particle target diameters. To determine if particle size impacted nutrient and oxygen permeability, small and large particles were incubated in vitro in a spinner flask with an abundance of culture media and vascular endothelial growth factor secretion was measured with enzyme-linked immunosorbent assay. Finally, small and large fat grafts were prepared from subcutaneous mouse fat pads and grafted in syngeneic Balb/CJ mice. Weight and volume retention were evaluated at 1, 4, 8, and 12 weeks. Histological analysis with Masson’s trichrome and perilipin immunofluorescent staining was performed. Real-time quantitative polymerase chain reaction was performed for adipogenic, inflammatory and apoptotic genes.Results: The range of fat particle diameters harvested with four commonly used cannulas was 2-7 mm. In vitro studies showed that 5-7-mm particles had significantly increased VEGF secretion normalized to weight, indicating increased tissue hypoxia in these particles compared to 2-4-mm particles. Surprisingly, in vivo comparison in two unique studies showed 2-4-mm and 5-7-mm fat particles had comparable graft retention (P = 0.5329). Masson’s trichrome staining revealed increased extracellular matrix and fibrosis in the 5-7-mm particle group (P = 0.0115). Adipocyte survival with perilipin demonstrated comparable viability. Gene expression showed large particles experienced increased inflammation and apoptosis at one week after grafting, but overall there were no significant differences between groups.Conclusion: The ideal fat particle size should be large enough to contain adequate mesenchyme while not so thick as to preclude imbibition. This study suggests that, despite changes in hypoxia and VEGF levels, differing fat particles (2-4-mm and 5-7-mm) can achieve similar graft retention