Coaxial injector spray characterization using water/air as simulants

Quantitative information about the atomization of injector sprays is required to improve the accuracy of computational models that predict the performance and stability of liquid propellant rocket engines. An experimental program is being conducted at NASA-Lewis to measure the drop size and velocity distributions in shear coaxial injector sprays. A phase/Doppler interferometer is used to obtain drop size data in water air shear coaxial injector sprays. Droplet sizes and axial component of droplet velocities are measured at different radii for various combinations of water flow rate, air flow rate, injector liquid jet diameter, injector annular gap, and liquid post recess. Sauter mean diameters measured in the spray center 51 mm downstream of the liquid post tip range from 28 to 68 microns, and mean axial drop velocities at the same location range from 37 to 120 m/s. The shear coaxial injector sprays show a high degree of symmetry; the mean drop size and velocity profiles vary with liquid flow rate, post recess, and distance from the injector face. The drop size data can be used to estimate liquid oxygen/hydrogen spray drop sizes by correcting property differences between water-air and liquid oxygen/hydrogen

Qualification Requirements for Foreign Corporations: The Need for a New Definition of Doing Business Based on In-State Sales Volume

Part I of this article examines the mechanics of the present qualification system, paying special attention to the problems created by a multiplicity of vague state standards. Part II discusses the historical justification and purposes of the present system, concluding that only the protection function justifies the continued existence of the system. Finally, Part III proposes that doing business be defined in terms of the annual volume of in-state sales. This solution would remedy the problems which plague the present system while furthering the legitimate protection function of the state qualification requirements

Shells and Stones: A Functional Examination of the Tuamotus Adze Kit.

M.A. Thesis. University of Hawaiʻi at Mānoa 2017

Summary Cultural Competency Initiative in the Greater Kansas City Region 2009-2013

The Cultural Competency Initiative (CCI) was designed and launched by the REACH Healthcare Foundation to increase the understanding and practice of cultural competency within nonprofit health and human service organizations in the foundation's six-county service area, with the ultimate goal of reducing disparities in health among poor and minority populations. This report provide a summary of the CCI and the lessons learned from 2009 through 2013. This summary is based on three formal evaluation reports prepared by the evaluator of the initiative, review of initiative meeting minutes and other documents, and interviews with the evaluator, the technical assistance provider, the funders, Steering Committee members and grantees

Size-and-shape space Gaussian mixture models for structural clustering of molecular dynamics trajectories

Determining the optimal number and identity of structural clusters from an ensemble of molecular configurations continues to be a challenge. Recent structural clustering methods have focused on the use of internal coordinates due to the innate rotational and translational invariance of these features. The vast number of possible internal coordinates necessitates a feature space supervision step to make clustering tractable, but yields a protocol that can be system type specific. Particle positions offer an appealing alternative to internal coordinates, but suffer from a lack of rotational and translational invariance, as well as a perceived insensitivity to regions of structural dissimilarity. Here, we present a method, denoted shape-GMM, that overcomes the shortcomings of particle positions using a weighted maximum likelihood (ML) alignment procedure. This alignment strategy is then built into an expectation maximization Gaussian mixture model (GMM) procedure to capture metastable states in the free energy landscape. The resulting algorithm distinguishes between a variety of different structures, including those indistinguishable by RMSD and pair-wise distances, as demonstrated on several model systems. Shape- GMM results on an extensive simulation of the the fast-folding HP35 Nle/Nle mutant protein support a 4-state folding/unfolding mechanism which is consistent with previous experimental results and provides kinetic detail comparable to previous state of the art clustering approaches, as measured by the VAMP-2 score. Currently, training of shape-GMMs is recommended for systems (or subsystems) that can be represented by . 200 particles and . 100K configurations to estimate high-dimensional covariance matrices and balance computational expense. Once a shape-GMM is trained, it can be used to predict the cluster identities of millions of configurations.Chemistr

Coupling between Voltage Sensors and Activation Gate in Voltage-gated K+ Channels

Current through voltage-gated K+ channels underlies the action potential encoding the electrical signal in excitable cells. The four subunits of a voltage-gated K+ channel each have six transmembrane segments (S1–S6), whereas some other K+ channels, such as eukaryotic inward rectifier K+ channels and the prokaryotic KcsA channel, have only two transmembrane segments (M1 and M2). A voltage-gated K+ channel is formed by an ion-pore module (S5–S6, equivalent to M1–M2) and the surrounding voltage-sensing modules. The S4 segments are the primary voltage sensors while the intracellular activation gate is located near the COOH-terminal end of S6, although the coupling mechanism between them remains unknown. In the present study, we found that two short, complementary sequences in voltage-gated K+ channels are essential for coupling the voltage sensors to the intracellular activation gate. One sequence is the so called S4–S5 linker distal to the voltage-sensing S4, while the other is around the COOH-terminal end of S6, a region containing the actual gate-forming residues

Giant supercurrent states in a superconductor-InAs/GaSb-superconductor junction

Superconductivity in topological materials has attracted a great deal of interest in both electron physics and material sciences since the theoretical predictions that Majorana fermions can be realized in topological superconductors [1-4]. Topological superconductivity could be realized in a type II, band-inverted, InAs/GaSb quantum well if it is in proximity to a conventional superconductor. Here we report observations of the proximity effect induced giant supercurrent states in an InAs/GaSb bilayer system that is sandwiched between two superconducting tantalum electrodes to form a superconductor-InAs/GaSb-superconductor junction. Electron transport results show that the supercurrent states can be preserved in a surprisingly large temperature-magnetic field (T-H) parameter space. In addition, the evolution of differential resistance in T and H reveals an interesting superconducting gap structure

Mechanism of Rectification in Inward-rectifier K+ Channels

Rectification in inward-rectifier K+ channels is caused by the binding of intracellular cations to their inner pore. The extreme sharpness of this rectification reflects strong voltage dependence (apparent valence is ∼5) of channel block by long polyamines. To understand the mechanism by which polyamines cause rectification, we examined IRK1 (Kir2.1) block by a series of bis-alkyl-amines (bis-amines) and mono-alkyl-amines (mono-amines) of varying length. The apparent affinity of channel block by both types of alkylamines increases with chain length. Mutation D172N in the second transmembrane segment reduces the channel's affinity significantly for long bis-amines, but only slightly for short ones (or for mono-amines of any length), whereas a double COOH-terminal mutation (E224G and E299S) moderately reduces the affinity for all bis-amines. The apparent valence of channel block increases from ∼2 for short amines to saturate at ∼5 for long bis-amines or at ∼4 for long mono-amines. On the basis of these and other observations, we propose that to block the channel pore one amine group in all alkylamines tested binds near the same internal locus formed by the COOH terminus, while the other amine group of bis-amines, or the alkyl tail of mono-amines, “crawls” toward residue D172 and “pushes” up to 4 or 5 K+ ions outwardly across the narrow K+ selectivity filter. The strong voltage dependence of channel block therefore reflects the movement of charges carried across the transmembrane electrical field primarily by K+ ions, not by the amine molecule itself, as K+ ions and the amine blocker displace each other during block and unblock of the pore. This simple displacement model readily accounts for the classical observation that, at a given concentration of intracellular K+, rectification is apparently related to the difference between the membrane potential and the equilibrium potential for K+ ions rather than to the membrane potential itself

A Successful Infusion Process for Enabling Lunar Exploration Technologies

The NASA Vision for Space Exploration begins with a more reliable flight capability to the International Space Station and ends with sending humans to Mars. An important stepping stone on the path to Mars encompasses human missions to the Moon. There is little doubt throughout the stakeholder community that new technologies will be required to enable this Vision. However, there are many factors that influence the ability to successfully infuse any technology including the technical risk, requirement and development schedule maturity, and, funds available. This paper focuses on effective infusion processes that have been used recently for the technologies in development for the lunar exploration flight program, Constellation. Recent successes with Constellation customers are highlighted for the Exploration Technology Development Program (ETDP) Projects managed by NASA Glenn Research Center (GRC). Following an overview of the technical context of both the flight program and the technology capability mapping, the process is described for how to effectively build an integrated technology infusion plan. The process starts with a sound risk development plan and is completed with an integrated project plan, including content, schedule and cost. In reality, the available resources for this development are going to change over time, necessitating some level of iteration in the planning. However, the driving process is based on the initial risk assessment, which changes only when the overall architecture changes, enabling some level of stability in the process