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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Development of an Efficient Enzyme Production and Structure-Based Discovery Platform for BACE1 Inhibitors

BACE1 (Beta-site Amyloid Precursor Protein (APP) Cleaving Enzyme 1) is a promising therapeutic target for Alzheimer’s Disease (AD). However, efficient expression, purification, and crystallization systems are not well described or detailed in the literature nor are approaches for treatment of enzyme kinetic data for potent inhibitors well described. As such, we developed a platform for expression and purification of BACE1, including protein refolding from E.coli inclusion bodies, in addition to optimizing a reproducible crystallization procedure of BACE1 bound with inhibitors. We also report a detailed approach to the proper analysis of enzyme kinetic data for compounds that exhibit either rapid-equilibrium or tight-binding mechanisms. Our methods allow for the purification of ~15 mg of BACE1 enzyme from 1 L of culture which is higher than reported yields in the current literature. To evaluate the data analysis approach developed here, a well-known potent inhibitor and two of its derivatives were tested, analyzed, and compared. The inhibitory constants (K i ) obtained from the kinetic studies are in agreement with dissociation constants (K d ) that were also determined using isothermal titration calorimetry (ITC) experiments. The X-ray structures of these three compounds in complex with BACE1 were readily obtained and provide important insight into the structure and thermodynamics of the BACE1-inhibitor interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Enabling high-throughput enzyme discovery and engineering with a low-cost, robot-assisted pipeline

Abstract As genomic databases expand and artificial intelligence tools advance, there is a growing demand for efficient characterization of large numbers of proteins. To this end, here we describe a generalizable pipeline for high-throughput protein purification using small-scale expression in E. coli and an affordable liquid-handling robot. This low-cost platform enables the purification of 96 proteins in parallel with minimal waste and is scalable for processing hundreds of proteins weekly per user. We demonstrate the performance of this method with the expression and purification of the leading poly(ethylene terephthalate) hydrolases reported in the literature. Replicate experiments demonstrated reproducibility and enzyme purity and yields (up to 400 µg) sufficient for comprehensive analyses of both thermostability and activity, generating a standardized benchmark dataset for comparing these plastic-degrading enzymes. The cost-effectiveness and ease of implementation of this platform render it broadly applicable to diverse protein characterization challenges in the biological sciences.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Heat Transfer Salts for Nuclear Reactor Systems - Chemistry Control, Corrosion Mitigation, and Modeling

The concept of a molten salt reactor has existed for nearly sixty years. Previously all work was done during a large collaborative effort at Oak Ridge National Laboratory, culminating in a research reactor which operated for 15,000 hours without major error. This technical success has garnished interest in modern, high temperature, reactor schemes. Research using molten fluoride salts for nuclear applications requires a steady supply of high grade molten salts. There is no bulk supplier of research grade fluoride salts in the world, so a facility which could provide all the salt needed for testing at the University of Wisconsin had to be produced. Two salt purification devices were made for this purpose, a large scale purifier, and a small scale purifier, each designed to clean the salts from impurities and reduce their corrosion potential. As of now, the small scale has performed with flibe salt, hydrogen, and hydrogen fluoride, yielding clean salt. This salt is currently being used in corrosion testing facilities at the Massachusetts Institute of Technology and the University of Wisconsin. Working with the beryllium based salts requires extensive safety measures and health monitoring to prevent the development of acute or chronic beryllium disease, two pulmonary diseases created by an allergic reaction to beryllium in the lungs. Extensive health monitoring, engineering controls, and environment monitoring had to be set up with the University of Wisconsin department of Environment, Health and Safety. The hydrogen fluoride required for purification was also an extreme health hazard requiring thoughtful planning and execution. These dangers have made research a slow and tedious process. Simple processes, such as chemical handling and clean-up, can take large amounts of ingenuity and time. Other work has complemented the experimental research at Wisconsin to advance high temperature reactor goals. Modeling work has been performed in house to re-evaluate thermophysical properties of flibe and flinak. Pacific Northwest National Laboratories has focused on evaluating the fluorinating gas nitrogen trifluoride as a potential salt purification agent. Work there was performed on removing hydroxides and oxides from flinak salt under controlled conditions. Lastly, the University of California Berkeley has spent considerable time designing and simulating reactor components with fluoride salts at high temperatures. Despite the hurdles presented by the innate chemical hazards, considerable progress has been made. The stage has been set to perform new research on salt chemical control which could advance the fluoride salt cooled reactor concept towards commercialization. What were previously thought of as chemical undesirable, but nuclear certified, alloys have been shown to be theoretically compatible with fluoride salts at high temperatures. This preliminary report has been prepared to communicate the construction of the basic infrastructure required for flibe, as well as suggest original research to performed at the University of Wisconsin. Simultaneously, the contents of this report can serve as a detailed, but introductory guide to allow anyone to learn the fundamentals of chemistry, engineering, and safety required to work with flibe salt.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2018

An Integrated Supercritical System for Efficient Produced Water Treatment and Power Generation

The main goal of this project was to evaluate the feasibility of an integrated supercritical (SC) water desalination and power generation system for treatment of produced waters from CO 2 sequestration, oil production, and coal-bed methane recovery. This system may offer a transformative approach to generating power from coal or natural gas (NG) and purifying saline water or produced water with high total dissolved solids (TDS) in a zero-liquid discharge plant. The closed-loop steam cycle of conventional power plants was replaced with an open-loop steam cycle that heated the pretreated produced water above the SC point of water (374 °C and 221 bar) to precipitate and separate the salts dissolved in the water. After separation of the precipitated salt, the SC steam required further treatment to reduce the salt content from ~100 mg/L (ppm) to <1 ppm to make it suitable for use in turbines for power generation. A SC membrane distillation unit was used to polish the SC steam, which could be sent through a series of turbines for power generation, and the steam exiting the low-pressure turbine could be condensed by cooling water to produce pure water. Project tasks included a process simulation and a techno-economic evaluation of the integrated system; design and assembly of SC salt precipitation and membrane distillation systems; development and characterization of advanced carbon membranes for SC membrane distillation; and pretreatment, desalination, and purification of different produced water samples with salt concentrations of 30,000–200,000 ppm to a high-purity (<1 ppm) level. Process simulations were performed for 550 MW SC coal-fired or NG baseline cases and various scenarios for the proposed integrated SC system using produced water as the water source and coal or NG as the fuel source. Simulation results indicated that the net plant efficiency loss of the proposed SC cogeneration process would be in the range of <1% to ~4%, in which NG and lower TDS produced water cases would have higher efficiencies. The proposed process for coal-fired cases could provide all water needs for the power generation process and generate additional pure water for beneficial use. A techno-economic analysis was performed to estimate the cost of produced water treatment (dollars /kgal of treated water) by conventional treatment processes compared with the proposed cogeneration process. The cost estimation for the proposed cogeneration system included the cost of pretreatment, the cost of power loss to integrate the water desalination process into the power generation system, and the cost of plant modification or retrofitting. The cost of produced water treatment was calculated by assuming three different scenarios in which converting a baseline power plant to the proposed cogeneration plant would increase the cost of the boiler and feed water system by 10%, 50%, and 100%. Results indicated that the cost of produced water treatment, even with a 100% cost increase, was in the range of $8.6–11.6 dollars per kgal, which is about half of the treatment cost by conventional methods. The cost of produced water treatment by the proposed cogeneration system could be further reduced or a considerable income could be generated if the values of saltwater and freshwater products are considered. Overall, the techno-economic analysis results indicated that the proposed integrated SC system could potentially treat produced water at a cost significantly lower than the cost of produced water treatment by conventional technologies. To evaluate the feasibility of the proposed treatment system at a laboratory scale, a SC salt precipitation and membrane distillation system was designed and fabricated to treat a simulated brine or pretreated produced water by precipitating salts and further polishing the SC steam containing ~100 ppm salts to a high-purity steam. Through baseline tests with NaCl solutions, with concentrations ranging from 30,000 to 200,000 ppm, it was demonstrated that concentrated feed solutions could be treated by precipitating salt at SC conditions to a TDS level of 130 ppm. Produced water samples were collected from a potential CO 2 sequestration site, a coal-bed methane site, and an oilfield in Illinois. Representative samples were characterized for various water quality parameters, including pH; turbidity; conductivity; and concentrations of selected anions, cations, alkalinity, dissolved organic carbon, total suspended solids, TDS, and total petroleum hydrocarbons. The produced water samples were first treated by conventional pretreatment methods to remove residual oil, dissolved organic matter, and scale-forming species. Pretreatment methods included coagulation, sedimentation, filtration, activated carbon adsorption, and ion-exchange adsorption. Pretreated produced waters were treated at SC conditions in which salts were precipitated. Analysis of treated samples revealed that the concentration of Na (the main cation) in produced waters was reduced dramatically from 14,000–47,400 ppm in the feed to 21–80 ppm in treated waters. Concentrations of other main cations (Ca, Mg, Sr, K) also decreased significantly from initial values of ~1,000–22,000 ppm to ~1 ppm or less. However, a significant increase in the concentrations of Fe, Ni, Cu, and Co was observed, mainly caused by leaching of these elements from the system (vessels, filters, tubing), which is manufactured from alloys containing Fe, Ni, Cu, and Co. To polish the SC steam containing a salt content of ~100 ppm to a high-purity level of <1 ppm, a SC membrane distillation treatment using carbon membranes was employed. Different types of self-standing or supported carbon membranes were developed from graphite, graphene, carbon nanotubes, carbon nanofibers, and pyrolytic carbon. Screening tests revealed that only a limited number of developed carbon membranes were suitable for the purification of steam at SC conditions. Membranes that were either fragile and lacked mechanical strength or had large pores and showed limited salt rejection (<20%) were found to be unsuitable for the purification of SC steam. Promising carbon membranes that were successfully tested for purifying SC steam included two graphite membranes (i.e., AF-5, a porous graphite material, and FGS, a flexible graphite sheet) and a carbon nanotube membrane grown on a Hastelloy substrate and then further modified using a proprietary method (i.e., membrane C). The AF-5 membrane exhibited a stable water flux of ~50 kg/m 2 ∙h and ~40% salt rejection. The FGS membrane had a high salt rejection of 95%–98% but a lower water flux of ~15 kg/m 2 ∙h. Membrane C showed an extremely high flux of 200-800 kg/m 2 ∙h, which is one order of magnitude higher than the water flux of conventional membranes. Membrane C also exhibited 87%–93% salt rejection. Overall, a two-stage or multistage polishing treatment by these membranes could lower the salt content of the SC steam from initial values of ~100–200 ppm to the steam quality of <1 ppm or to parts per billion levels required for the power cycle.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2020

Recovery of High Purity Rare Earth Elements (REE) from Coal Ash via a Novel Electrowinning Process (Final Report)

The goal of this project was to produce a high purity, separated (>90%) rare earth oxide (REO) product from coal-based sources. This product was achieved using the following three steps: 1. Battelle’s ADP: The ADP process involves pretreatment of ash (milling and caustic leaching), leaching of pretreated ash with nitric acid, roasting of loaded acid solution containing REE, and water leaching of residual from roasting step, resulting in a REE pregnant solution. 2. Solvent Extraction (SX) Upgrading: The SX involves the extraction of REE from a pregnant REE solution using an organic extractant (note after extraction, the aqueous phase was a residual solution and the organic phase contained REE), and stripping of REE from the organic phase product obtained from the extraction using an acid solution (the stripped solution was the final purified product containing REE, organic traces, and traces of other metals for further separation in the electrowinning process). 3. Rare Earth Salts’ (RES) Electrochemical Separation and Purification Process: The staged electrochemical process was separated REO products from the mixed REE solution. Testing by RES was also included in the investigation of options to minimize the solvent extraction steps. This report covers laboratory testing, production of a high purity coal-based REO, process design of the overall REE recovery and purification process, technoeconomic assessment (TEA), and a commercialization plan discussing the overall REE recovery and purification process.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2020

Catalytic Removal of Oxygen and Pollutants in Exhaust Gases from Pressurized Oxy-Combustors

The primary goal of this project was to develop and validate advanced catalytic materials and systems for purifying the flue gas generated from pressurized oxy-combustors in an effort to achieve the purity specifications of carbon dioxide (CO 2 ) streams required by the U.S. Department of Energy (USDOE) for application in enhanced oil recovery. The technology has shown great potential for improving energy efficiency, simplifying process complexity, and lowering costs compared with current state-of-the-art oxy-combustion flue gas purification technologies. Laboratory studies were conducted for the development, characterization, and screening of metal catalysts for residual oxygen (O 2 ) reduction with methane (CH 4 ) and multifunctional carbon catalysts for combined nitrogen oxides (NO x ), sulfur oxides (SO x ), and mercury (Hg) removal. A bench-scale reverse-flow fixed-bed (RFFB) reactor and a trickle-bed direct-contact cooler (DCC) reactor capable of treating 15 standard liters per min of pressurized oxy-combustion flue gas were fabricated and tested with both a simulated flue gas in the laboratory and a slipstream of actual flue gas at a 100 kW th Staged, Pressurized Oxy-Combustion (SPOC) pilot facility. Process simulation and techno-economic studies were performed to evaluate the energy efficiency and cost of the developed catalytic flue gas purification process integrated into a conceptual 550-MWe SPOC power plant. The goal and objectives of the project have been successfully accomplished. A cobalt-manganese (CoMn) oxide catalyst was developed and demonstrated in the bench-scale RFFB reactor in either a reverse-flow or one-direction flow mode of operation that met the success criterion of performance for residual O 2 reduction. A carbon catalyst was developed and demonstrated in the bench-scale DCC reactor that met the success criterion of performance for combined NO x /SO x /Hg removal. Slipstream testing of the integrated DCC-RFFB system at the SPOC pilot facility demonstrated stable operation and verified the superior performance obtained in the laboratory. The techno-economic analysis showed that a 550-MWe SPOC plant integrated with the catalytic flue gas purification process would result in costs of electricity of $\$$96.94/MWh and $\$$80.27/MWh in two assessed cases compared with $\$$91.07/MWh reported for the USDOE’s Current Technology Case, which generated only a partially pure CO 2 stream. On the basis of the results and findings from this project, scale-up studies of materials production and system demonstration and optimization studies of reactors and processes are recommended at the next stage of technology development.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2023

CHALLENGES IN THE DEVELOPMENT OF THE ELECTROREFINING PROCESS AT Y-12

In order to ensure future capabilities of the Y-12 site as older buildings retire, a new process was developed, the Metal Purification Process. The purpose of this new process is to provide a simpler and more efficient uranium metal purification that the previous multi-staged, complex chemical processes. The basis for this technology currently exists in the US DOE complex, but it has not been utilized on a large scale for uranium at higher enrichments. The system requires larger-geometry vessels and furnaces in order to meet the through-put requirements. The crux of the process is the electrorefining cell, consisting of several concentric liners and an unfavorable geometry cylindrical crucible. Within the crucible, a molten Li-CL-KCL-UCL3 salt electrolyte is present. ‘Dirty’ metal is placed into a loading basket and loaded into an electrorefining cell. Here, the metal reacts into the molten salt within the cell to form UCL3, while ‘clean’ metal simultaneously plates out from the salt electrolyte in the form of metal dendrites. These dendrites are then collected and removed from the cell. After removal from the cell, the dendrites are taken to a furnace to remove adhered salts. Then, the salt-free dendrites are moved to a separate furnace for consolidation into the final product form. The development of the Criticality Safety Evaluation for this complex system brought with it many NCS Challenges and lessons learned. These challenges include: design decisions for ensuring subcriticalty in the electrorefining cell during abnormal conditions, the interface of the main glovebox system with auxiliary systems such as the purification system and designated storage, implementation of mass tracking, and concerns from production and operation regarding the movement of material within the system.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Ion separations with membranes

Ion separations are important for resource recovery, water treatment, and energy production and storage. Techniques such as chemical precipitation, selective adsorption, and solvent extraction are effective, but membranes may separate ions continuously with less waste and lower energy costs. Separation of monovalent and multivalent ions with nanofiltration or electrodialysis membranes already enables water softening and edible salt purification. Similar membranes are attractive as separators in vanadium redox flow batteries. Selective partitioning of divalent counter-ions into ion-exchange membranes even allows transport of these ions against their concentration gradients in salt mixtures. However, separations of ions with the same charge is more challenging. Recent research demonstrated highly selective ion “sieving” at small scales. Here, separations using electrical potentials and differences in ion electrophoretic mobilities are promising, but relatively unexplored. Carrier-mediated transport affords high selectivity in liquid membranes, but these systems are not very stable, and selective transport via hopping between anchored carriers has proven elusive. Finally, this paper discusses how concentration polarization decreases selectivities in many membrane processes. Although development of selective, inexpensive ion-separation membranes is a work in progress, successes in water softening and edible salt purification suggests that future selective membranes will serve as complementary methods to traditional purification techniques.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Mechanically robust hydrophobized double network hydrogels and their fundamental salt transport properties

Abstract Water swollen polymer networks are attractive for applications ranging from tissue regeneration to water purification. For water purification, charged polymers provide excellent ion separation properties. However, many ion exchange membranes (IEMs) are brittle, necessitating the use of thick support materials that ultimately decrease throughput. To this end, novel double network hydrogels (DNHs) with variable water content are prepared and characterized in terms of mechanical and ion transport properties to evaluate their potential utility as tough membrane materials. The first network contains fixed anionic charges, while the other is comprised of a copolymer with varied ratios of hydrophobic ethyl acrylate (EA) and hydrophilic dimethyl acrylamide (DMA) repeat units. Characterization of freestanding DNH films reveals a reduction in water content from 88 to 53 wt% and a simultaneous increase in ultimate stress and strain by ~3.5× and ~4.5×, respectively, for 95%/5% EA/DMA, relative to 100% DMA. Fundamental salt transport properties relevant to water purification, including permeability, solubility, and diffusivity, are measured and systematically compared with conventional membrane materials to inform the development of DNHs for membrane applications. The ability to simultaneously reduce water content and increase mechanical integrity highlights the potential of DNHs as a synthetic platform for future membrane applications.

Allen, Marshall J.↗
DOE OSTI2017

The Plasmodium falciparum exported protein PF3D7_0402000 binds to erythrocyte ankyrin and band 4.1

Plasmodium proteins are exported to the erythrocyte cytoplasm to create an environment that supports parasite replication. Although hundreds of proteins are predicted to be exported through PEXEL-dependent and -independent mechanisms, the functions of exported proteins are largely uncharacterized. In this study, we used a biochemical screening approach to identify exported P. falciparum proteins that bound to inside-out vesicles prepared from erythrocytes. Out of 70 exported P. falciparum proteins tested, 18 bound to IOVs in 2 or more independent assays. Using co-affinity purifications followed by mass spectrometry, pairwise co-purification experiments and the split-luciferase assay, we identified 31 putative protein-protein interactions between erythrocyte cytoskeletal proteins and exported P. falciparum proteins. We further showed that PF3D7_1401600 binds to the spectrin-binding domain of erythrocyte ankyrin via its MESA erythrocyte cytoskeleton binding (MEC) motif and to the N-terminal domains of ankyrin and 4.1R through a fragment that required an intact PHIST domain. Introduction of PF3D7_1401600 into erythrocyte ghosts increased retention in the microsphiltration assay, consistent with previous data that reported a reduction of rigidity in red blood cells infected with PF3D7_1401600-deficient parasites. Finally, we found that PfEPF3 proteins bound to erythrocyte GAPDH, providing a potential link between Maurer’s clefts and the erythrocyte cytoskeleton early during infection.

Shakya, Bikash↗
DOE OSTI2017

Characterization of natural organic matter in low-carbon sediments: Extraction and analytical approaches

Sediment-associated natural organic matter (NOM) is a complex assemblage of organic molecules with a wide range of sizes, functional groups, and structures, which is intricately associated with mineral particles. Organic carbon (OC) concentrations in subsurface sediments are typically 10 to 200 times lower than in surface soils, posing a distinct challenge for characterization. A range of chemical extractions were evaluated for extraction of NOM, and a NOM extraction scheme was developed using a combination of sequential extraction with water (MQ) and sodium pyrophosphate at pH 10 (PP), and purification by dialysis and solid phase extraction in order to isolate different fractions of sediment-associated NOM. Analysis of these different NOM fractions was then carried out by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The OC extraction efficiency of the tested extractions followed the order PP>NaOH>HCl=hydroxylamine hydrochloride>dithionite. Greater concentrations of OC in PP vs NaOH extracts suggest that metal complexation and/or ligand exchange plays an important role in OC stabilization. Characterization of different pools of extraction NOM by FITR shows that the water soluble fraction has a higher fraction of aliphatic and carboxylic groups, while the PP fractions have higher C=C groups. This trend from aliphatic to more aromatic is also supported by the UV-Vis and ESI-FTICR-MS data.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2024

Downstream Separation of Formic Acid with Anion-Exchange Resin from Electrocatalytic Carbon Dioxide (CO 2 ) Conversion: Adsorption, Kinetics, and Equilibrium Modeling

The electrocatalytic carbon dioxide reduction reaction (CO 2 RR) that produces liquid formic acid (FA) is one potential route to minimize the CO 2 concentration in the atmosphere by utilizing CO 2 as a feedstock. However, one of the main disadvantages of this route is the high energy demand required for purification through conventional distillation. This method of purification has been shown to result in a large carbon footprint in life-cycle analysis (LCA). Therefore, finding an alternative purification technique that can integrate with an electrochemical CO 2 RR process with the potential to lower the carbon footprint would be of great interest. Under the experimental conditions of the CO 2 RR, FA remains in its basic form as the formate anion in the catholyte. Anion exchange resins with their basic properties can separate the formate anion from the catholyte mixture as an alternative to energy intensive distillation. In this work, three anion exchange resins with increasing basicity order: Amberlite IRA-96 < Amberlite IRA-910 < Ambersep 900 are tested to separate FA in the presence of aqueous solution of potassium bicarbonate catholyte with varying levels of resin and FA. Kinetics and equilibrium studies data for the FA adsorption are interpreted using several kinetics and isotherm models. The kinetics data fit well with a pseudo-first-order model at high initial FA concentrations and a pseudo-second-order model at low initial FA concentrations. The experimental data can be best explained with the Freundlich isotherm model. The fitted results show that strongly basic Ambersep 900 is more effective at separating FA, with a maximum adsorption capacity of 336.7 mg/g compared to Amberlite IRA-96 (275.2 mg/g) and Amberlite IRA-910 (209.2 mg/g) in neutral water. However, weakly basic Amberlite IRA-96 (110.8 mg/g) can separate FA more efficiently from potassium bicarbonate catholyte than Amberlite IRA-910 (99.9 mg/g) and Ambersep 900 (40.0 mg/g). As a result, competitive adsorption occurs in the presence of potassium bicarbonate catholyte, but the formic acid adsorption capacity is still sufficient for adequate separation.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2026

Modeling Flow and Mass Transfer within Hollow Fiber Packaging for Gas Separation

Hollow fiber membrane modules are used for gas purification by their selective permeation properties. Intensification of the process to minimize the retentate loss and gas pressure involves optimization at various scales. In this work, we outline a numerical investigation of the gas separation performance at the scale of fiber bundles and its impact on module performance. Flow channeling and anisotropy govern the mass-transfer coefficient in axial and cross-flow configurations. These effects are quantified in terms of a permeability tensor or an anisotropy ratio and the effective mass-transfer coefficient or the Sherwood number. The results show a trade-off between purification and recovery. While smaller fibers offer a large specific surface area to enable high purification, it comes at a huge penalty on the separation performance due to reduced penetration within bundles. Optimum performance indicators are emphasized.

Fibers↗
DOE OSTI2015

Results from KamLAND-Zen

KamLAND-Zen reports on a preliminary search for neutrinoless double-beta decay with 136 Xe based on 114.8 live-days after the purification of the xenon loaded liquid scintillator. In this data, the problematic 110m Ag background peak identified in previous searches is reduced by more than a factor of 10. By combining the KamLAND-Zen pre- and post-purification data, we obtain a preliminary lower limit on the 0νββ decay half-life of T 0ν 1/2 > 2.6×10 25 yr at 90% C.L. The search sensitivity will be enhanced with additional low background data after the purification. As a result, prospects for further improvements with future KamLAND-Zen upgrades are also presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Impurity-induced deep centers in Tl 6 SI 4

Tl 6 SI 4 is a promising material for room-temperature semiconductor radiation detection applications. The history of the development of semiconductor radiation detection materials has demonstrated that impurities strongly affect the carrier transport and that material purification is a critically important step in improving the carrier transport and thereby the detector performance. Here, we report combined experimental and theoretical studies of impurities in Tl 6 SI 4 . Impurity concentrations in Tl 6 SI 4 were analyzed by glow discharge mass spectrometry. Purification of the raw material by multi-pass vertical narrow zone refining was found to be effective in reducing the concentrations of most impurities. Density functional theory calculations were also performed to study the trapping levels introduced by the main impurities detected in experiments. We show that, among dozens of detected impurities, most are either electrically inactive or shallow. In the purified Tl 6 SI 4 sample, only Bi has a significant concentration (0.2 ppm wt) and introduces deep electron trapping levels in the band gap. Lastly, improvement of the purification processes is expected to further reduce the impurity concentrations and their impact on carrier transport in Tl 6 SI 4 , leading to improved detector performance.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Status of LBNF/DUNE near site liquid argon proximity and external cryogenics systems development.

The Deep Underground Neutrino Experiment (DUNE) near site located at Fermilab will host the neutrino beam complex. It includes a high voltage liquid argon time projection chamber located 60-meter underground used as beamline instrumentation. The LAr cryogenic system provided by the Long-Baseline Neutrino Facility (LBNF) regulates thermohydraulic conditions of the membrane cryostat hosting the detector with 285 Ton purified LAr. The purification system uses molecular sieve and copper oxide pellets to manage the argon contamination below 100 ppt (parts per trillion) oxygen equivalent. The detector and its cryogenics are capable to move a stroke of 30 meters on/off beam. The cryogenic system modes of operation include the cryostat pressure test, purge in open loop, detector cooldown, cryostat fill, closed loop purification, liquid empty, and purification system activation/regeneration process. The system design status and schedule, and technical details such as operating modes and interfaces are reported in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Protein stability: a crystallographer’s perspective

An understanding of protein stability is essential for optimizing the expression, purification and crystallization of proteins. In this review, discussion will focus on factors affecting protein stability on a somewhat practical level, particularly from the view of a protein crystallographer. Protein stability is a topic of major interest for the biotechnology, pharmaceutical and food industries, in addition to being a daily consideration for academic researchers studying proteins. An understanding of protein stability is essential for optimizing the expression, purification, formulation, storage and structural studies of proteins. In this review, discussion will focus on factors affecting protein stability, on a somewhat practical level, particularly from the view of a protein crystallographer. The differences between protein conformational stability and protein compositional stability will be discussed, along with a brief introduction to key methods useful for analyzing protein stability. Finally, tactics for addressing protein-stability issues during protein expression, purification and crystallization will be discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Isolation of 163 Ho from dysprosium target material by HPLC for neutrino mass measurements

The rare earth isotope 163 Ho is of interest for neutrino mass measurements. This report describes the isolation of 163 Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, 163 Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm –3 α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized by MC-ICP-MS to determine the 163 Ho/ 165 Ho ratio, 163 Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4E5 for Dy. As a result, the isolated Ho fraction contained 24.8 ±1.3 ng of 163 Ho corresponding to holmium recovery of 72 ± 3%.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗