18 research outputs found
Optimization of a Nafion Membrane-Based System for Removal of Chloride and Fluoride from Lunar Regolith-Derived Water
A long-term human presence in space will require self-sustaining systems capable of producing oxygen and potable water from extraterrestrial sources. Oxygen can be extracted from lunar regolith, and water contaminated with hydrochloric and hydrofluoric acids is produced as an intermediate in this process. We investigated the ability of Nafion proton exchange membranes to remove hydrochloric and hydrofluoric acids from water. The effect of membrane thickness, product stream flow rate, and acid solution temperature and concentration on water flux, acid rejection, and water and acid activity were studied. The conditions that maximized water transport and acid rejection while minimizing resource usage were determined by calculating a figure of merit. Water permeation is highest at high solution temperature and product stream flow rate across thin membranes, while chloride and fluoride permeation are lowest at low acid solution temperature and concentration across thin membranes. The figure of merit varies depending on the starting acid concentration; at low concentration, the figure of merit is highest across a thin membrane, while at high concentration, the figure of merit is highest at low solution temperature. In all cases, the figure of merit increases with increasing product stream flow rate
Contaminant Removal from Oxygen Production Systems for In Situ Resource Utilization
The In Situ Resource Utilization (ISRU) project has been developing technologies to produce oxygen from lunar regolith to provide consumables to a lunar outpost. The processes developed reduce metal oxides in the regolith to produce water, which is then electrolyzed to produce oxygen. Hydrochloic and hydrofluoric acids are byproducts of the reduction processes, as halide minerals are also reduced at oxide reduction conditions. Because of the stringent water quality requirements for electrolysis, there is a need for a contaminant removal process. The Contaminant Removal from Oxygen Production Systems (CROPS) team has been developing a separation process to remove these contaminants in the gas and liquid phase that eliminates the need for consumables. CROPS has been using Nafion, a highly water selective polymeric proton exchange membrane, to recover pure water from the contaminated solution. Membrane thickness, product stream flow rate, and acid solution temperature and concentration were varied with the goal of maximizing water permeation and acid rejection. The results show that water permeation increases with increasing solution temperature and product stream flow rate, while acid rejection increases with decreasing solution temperature and concentration. Thinner membranes allowed for higher water flux and acid rejection than thicker ones. These results were used in the development of the hardware built for the most recent Mars ISRU demonstration project
A microfluidic-based protein crystallization method in 10 micrometer-sized crystallization space
Protein crystallization and subsequent X-ray diffraction analysis of the three-dimensional structure are necessary for elucidation of the biological functions of proteins and effective rational drug design. Therefore, controlling protein crystallization is important to obtain high resolution X-ray diffraction data. Here, a simple microfluidic method using chips with 10 and 50 μm high crystallization chambers to selectively form suitable single protein crystals for X-ray analysis is demonstrated. As proof of concept, three different types of proteins: lysozyme, glucokinase from Pseudoalteromonas sp. AS-131 (PsGK), and NADPH-cytochrome P450 oxidoreductase–heme oxygenase complex were crystallized. We demonstrate that the crystal growth orientation depends on the height of the crystallization chamber regardless of the protein type. Our results suggest that the confined micro space induces the protein molecules to adhere to a specific crystal face and affects the growth kinetics of each crystal face. The present microfluidic-based protein crystallization method can reform a suitable single protein crystal for X-ray analysis from aggregates of needle-shaped protein crystals
X‑ray Transparent Microfluidic Chip for Mesophase-Based Crystallization of Membrane Proteins and On-Chip Structure Determination
Crystallization
from lipidic mesophase matrices is a promising
route to diffraction-quality crystals and structures of membrane proteins.
The microfluidic approach reported here eliminates two bottlenecks
of the standard mesophase-based crystallization protocols: (i) manual
preparation of viscous mesophases and (ii) manual harvesting of often
small and fragile protein crystals. In the approach reported here,
protein-loaded mesophases are formulated in an X-ray transparent microfluidic
chip using only 60 nL of the protein solution per crystallization
trial. The X-ray transparency of the chip enables diffraction data
collection from multiple crystals residing in microfluidic wells,
eliminating the normally required manual harvesting and mounting of
individual crystals. We validated our approach by on-chip crystallization
of photosynthetic reaction center, a membrane protein from <i>Rhodobacter sphaeroides</i>, followed by solving its structure
to a resolution of 2.5 Å using X-ray diffraction data collected
on-chip under ambient conditions. A moderate conformational change
in hydrophilic chains of the protein was observed when comparing the
on-chip, room temperature structure with known structures for which
data were acquired under cryogenic conditions
A microfluidic-based protein crystallization method in 10 micrometer-sized crystallization space
A microfluidic-based protein crystallization method in 10 micrometer-sized crystallization space
Chemical Analysis of Drug Biocrystals: A Role for Counterion Transport Pathways in Intracellular Drug Disposition
In mammals, highly lipophilic small
molecule chemical agents can
accumulate as inclusions within resident tissue macrophages. In this
context, we characterized the biodistribution, chemical composition,
and structure of crystal-like drug inclusions (CLDIs) formed by clofazimine
(CFZ), a weakly basic lipophilic drug. With prolonged oral dosing,
CFZ exhibited a significant partitioning with respect to serum and
fat due to massive bioaccumulation and crystallization in the liver
and spleen. The NMR, Raman, and powder X-ray diffraction (p-XRD) spectra
of CLDIs isolated from the spleens of CFZ-treated mice matched the
spectra of pure, CFZ hydrochloride crystals (CFZ-HCl). Elemental analysis
revealed a 237-fold increase in chlorine content in CLDIs compared
to untreated tissue samples and a 5-fold increase in chlorine content
compared to CFZ-HCl, suggesting that the formation of CLDIs occurs
through a chloride mediated crystallization mechanism. Single crystal
analysis revealed that CFZ-HCl crystals had a densely packed orthorhombic
lattice configuration. <i>In vitro</i>, CFZ-HCl formed at
a pH of 4–5 only if chloride ions were present at sufficiently
high concentrations (>50:1 Cl<sup>–</sup>/CFZ), indicating
that intracellular chloride transport mechanisms play a key role in
the formation of CLDIs. While microscopy and pharmacokinetic analyses
clearly revealed crystallization and intracellular accumulation of
the drug <i>in vivo</i>, the chemical and structural characterization
of CLDIs implicates a concentrative, chloride transport mechanism,
paralleling and thermodynamically stabilizing the massive bioaccumulation
of a weakly basic drug