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Howard, Jeanie

Publications and source records attributed to Howard, Jeanie.

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Evaluation of Brine Processing Technologies for Spacecraft Wastewater

Brine drying systems may be used in spaceflight. There are several advantages to using brine processing technologies for long-duration human missions including a reduction in resupply requirements and achieving high water recovery ratios. The objective of this project was to evaluate four technologies for the drying of spacecraft water recycling system brine byproducts. The technologies tested were NASA's Forward Osmosis Brine Drying (FOBD), Paragon's Ionomer Water Processor (IWP), NASA's Brine Evaporation Bag (BEB) System, and UMPQUA's Ultrasonic Brine Dewatering System (UBDS). The purpose of this work was to evaluate the hardware using feed streams composed of brines similar to those generated on board the International Space Station (ISS) and future exploration missions. The brine formulations used for testing were the ISS Alternate Pretreatment and Solution 2 (Alt Pretreat). The brines were generated using the Wiped-film Rotating-disk (WFRD) evaporator, which is a vapor compression distillation system that is used to simulate the function of the ISS Urine Processor Assembly (UPA). Each system was evaluated based on the results from testing and Equivalent System Mass (ESM) calculations. A Quality Function Deployment (QFD) matrix was also developed as a method to compare the different technologies based on customer and engineering requirements.

recycling↗
NASA NTRS2004

A Robust and Engineerable Self-Assembling Protein Template for the Synthesis and Patterning of Ordered Nanoparticle Arrays

Self-assembling biomolecules that form highly ordered structures have attracted interest as potential alternatives to conventional lithographic processes for patterning materials. Here we introduce a general technique for patterning materials on the nanoscale using genetically modified protein cage structures called chaperonins that self-assemble into crystalline templates. Constrained chemical synthesis of transition metal nanoparticles is specific to templates genetically functionalized with poly-Histidine sequences. These arrays of materials are ordered by the nanoscale structure of the crystallized protein. This system may be easily adapted to pattern a variety of materials given the rapidly growing list of peptide sequences selected by screening for specificity for inorganic materials.

McMillan, R. Andrew↗
NASA NTRS2003

Intracellular localization of a group II chaperonin indicates a membrane-related function

Chaperonins are protein complexes that are believed to function as part of a protein folding system in the cytoplasm of the cell. We observed, however, that the group II chaperonins known as rosettasomes in the hyperthermophilic archaeon Sulfolobus shibatae, are not cytoplasmic but membrane associated. This association was observed in cultures grown at 60 degrees C and 76 degrees C or heat-shocked at 85 degrees C by using immunofluorescence microscopy and in thick sections of rapidly frozen cells grown at 76 degrees C by using immunogold electron microscopy. We observed that increased abundance of rosettasomes after heat shock correlated with decreased membrane permeability at lethal temperature (92 degrees C). This change in permeability was not seen in cells heat-shocked in the presence of the amino acid analogue azetidine 2-carboxylic acid, indicating functional protein synthesis influences permeability. Azetidine experiments also indicated that observed heat-induced changes in lipid composition in S. shibatae could not account for changes in membrane permeability. Rosettasomes purified from cultures grown at 60 degrees C and 76 degrees C or heat-shocked at 85 degrees C bind to liposomes made from either the bipolar tetraether lipids of Sulfolobus or a variety of artificial lipid mixtures. The presence of rosettasomes did not significantly change the transition temperature of liposomes, as indicated by differential scanning calorimetry, or the proton permeability of liposomes, as indicated by pyranine fluorescence. We propose that these group II chaperonins function as a structural element in the natural membrane based on their intracellular location, the correlation between their functional abundance and membrane permeability, and their potential distribution on the membrane surface.

Cell Membrane/physiology/ultrastructure↗
NASA NTRS2002

Ordered nanoparticle arrays formed on engineered chaperonin protein templates

Traditional methods for fabricating nanoscale arrays are usually based on lithographic techniques. Alternative new approaches rely on the use of nanoscale templates made of synthetic or biological materials. Some proteins, for example, have been used to form ordered two-dimensional arrays. Here, we fabricated nanoscale ordered arrays of metal and semiconductor quantum dots by binding preformed nanoparticles onto crystalline protein templates made from genetically engineered hollow double-ring structures called chaperonins. Using structural information as a guide, a thermostable recombinant chaperonin subunit was modified to assemble into chaperonins with either 3 nm or 9 nm apical pores surrounded by chemically reactive thiols. These engineered chaperonins were crystallized into two-dimensional templates up to 20 microm in diameter. The periodic solvent-exposed thiols within these crystalline templates were used to size-selectively bind and organize either gold (1.4, 5 or 10nm) or CdSe-ZnS semiconductor (4.5 nm) quantum dots into arrays. The order within the arrays was defined by the lattice of the underlying protein crystal. By combining the self-assembling properties of chaperonins with mutations guided by structural modelling, we demonstrate that quantum dots can be manipulated using modified chaperonins and organized into arrays for use in next-generation electronic and photonic devices.

Chaperonins/chemistry/ultrastructure↗
NASA NTRS2000

H2O Adsorption Kinetics on Smectites

The adsorptive equilibration of H2O a with montomorillonite, a smectite clay has been measured. At low temperatures and pressures, equilibration can require many hours, effectively preventing smectites at the martian surface from responding rapidly to diurnal pressure and temperature variations.

Zent, Aaron P.↗