Crystal Structure of Phototoxic Orange Fluorescent Proteins with a Tryptophan-Based Chromophore
Abstract not provided
Pletneva, Nadya V.↗
SEARCH · Engineering Papers
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Evaluating kratom alkaloids using PHASE
Kratom is a botanical substance that is marketed and promoted in the US for pharmaceutical opioid indications despite having no US Food and Drug Administration approved uses. Kratom contains over forty alkaloids including two partial agonists at the mu opioid receptor, mitragynine and 7-hydroxymitragynine, that have been subjected to the FDA’s scientific and medical evaluation. However, pharmacological and toxicological data for the remaining alkaloids are limited. Therefore, we applied the Public Health Assessment via Structural Evaluation (PHASE) protocol to generate in silico binding profiles for 25 kratom alkaloids to facilitate the risk evaluation of kratom. PHASE demonstrates that kratom alkaloids share structural features with controlled opioids, indicates that several alkaloids bind to the opioid, adrenergic, and serotonin receptors, and suggests that mitragynine and 7-hydroxymitragynine are the strongest binders at the mu opioid receptor. Subsequently, the in silico binding profiles of a subset of the alkaloids were experimentally verified at the opioid, adrenergic, and serotonin receptors using radioligand binding assays. The verified binding profiles demonstrate the ability of PHASE to identify potential safety signals and provide a tool for prioritizing experimental evaluation of high-risk compounds.
60 APPLIED LIFE SCIENCES↗
Assessment of software methods for estimating protein-protein relative binding affinities
A growing number of computational tools have been developed to accurately and rapidly predict the impact of amino acid mutations on protein-protein relative binding affinities. Such tools have many applications, for example, designing new drugs and studying evolutionary mechanisms. In the search for accuracy, many of these methods employ expensive yet rigorous molecular dynamics simulations. By contrast, non-rigorous methods use less exhaustive statistical mechanics, allowing for more efficient calculations. However, it is unclear if such methods retain enough accuracy to replace rigorous methods in binding affinity calculations. This trade-off between accuracy and computational expense makes it difficult to determine the best method for a particular system or study. Here, eight non-rigorous computational methods were assessed using eight antibody-antigen and eight non-antibody-antigen complexes for their ability to accurately predict relative binding affinities (ΔΔG) for 654 single mutations. In addition to assessing accuracy, we analyzed the CPU cost and performance for each method using a variety of physico-chemical structural features. This allowed us to posit scenarios in which each method may be best utilized. Most methods performed worse when applied to antibody-antigen complexes compared to non-antibody-antigen complexes. Rosetta-based JayZ and EasyE methods classified mutations as destabilizing (ΔΔG < -0.5 kcal/mol) with high (83–98%) accuracy and a relatively low computational cost for non-antibody-antigen complexes. Some of the most accurate results for antibody-antigen systems came from combining molecular dynamics with FoldX with a correlation coefficient (r) of 0.46, but this was also the most computationally expensive method. Overall, our results suggest these methods can be used to quickly and accurately predict stabilizing versus destabilizing mutations but are less accurate at predicting actual binding affinities. This study highlights the need for continued development of reliable, accessible, and reproducible methods for predicting binding affinities in antibody-antigen proteins and provides a recipe for using current methods.
59 BASIC BIOLOGICAL SCIENCES↗
Physico-chemical properties of lignin fractions from acid pretreated corn stover and their effects on enzymatic hydrolysis of microcrystalline cellulose
Lignin has been shown to be a recalcitrance factor in many biomass conversion studies. To better understand the effects of lignin on cellulose conversion, different lignin fractions were extracted from the same dilute acid pretreated corn stover by three sequential isolation methods, namely ethanol extraction, dioxane extraction, and enzyme purification. The physicochemical properties of each lignin fraction including molecular weight distribution, surface area, surface charge, and other structural features varied, depending on the isolation methods. All three lignin fractions had negative surface charges, and ethanol-extracted lignin carried the highest surface charges, followed by dioxane-extracted lignin and cellulase-purified residual lignin. These physicochemical properties of lignin fractions also resulted in different extent of inhibitory effects on enzymatic hydrolysis of microcrystalline cellulose (MCC). Dioxane-extracted lignin exhibited the highest inhibitory effect on glucose release from MCC, followed by the cellulase-purified residual lignin fraction and ethanol-extracted lignin. Furthermore, lignin fractions with higher contents of syringyl (S) substructure and β-O-4 aryl ether interunit linkages showed a stronger negative effect on cellulase hydrolysis of MCC.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Core-flood Effluent and Shale Surface Chemistries in Predicting Interaction between Shale, Brine, and Reactive Fluid
We report field and laboratory observations to date indicate that the efficiency of hydraulic fracturing, as it relates to hydrocarbon recovery, depends significantly on geochemical alterations to rock surfaces that diminish accessibility by partial or total plugging of the pore and fracture networks. This is caused by mineral scale deposition such as coating of fracture surfaces with precipitates, particle migration, and/or crack closure due to dissolution under stress. In reactive flow-through experiments, mineral reactions in response to acidic fluid injection significantly reduced system porosity and core permeability. The present study focuses on changes to fluid chemistry and shale surfaces (inlet and fracture walls) resulting from shale-fluid interactions and integrating these findings for an improved estimate of transport-related consequences. The reacted shale surfaces were examined by spatially-resolved scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS) analysis. Importantly, inductively coupled plasma - mass spectrometry/optical emission spectroscopy (ICP-MS/OES) was utilized to probe the chemical evolution of the core-flood effluents. The three study cores selected from the Marcellus formation represent different mineralogies and structural features. In flow-through experiments, lab-generated brine and HCl-based fracture fluid (pH=2) were injected sequentially under effective stress (up to 500 psi) at reservoir temperature (80°C). SEM-EDS results confirmed by the ICP concentration trends showed significant Fe hydroxide precipitates in clay- and pyrite-rich outcrop samples due to partial oxidation of Fe-bearing phases in the case of intrusion of low salinity water-based fluids. Porosity reduction in the MSEEL (Marcellus Shale Energy and Environmental Laboratory) carbonate-rich sample is related to compaction of cores under stress due to matrix softening with substantial dissolution, and pore-filling by hydroxides, as well as barite and salts. Despite the same fluid compositions and experimental conditions used for both MSEEL samples, barite precipitation was much more intense in the MSEEL clay-rich sample due to its greater sorption capacity and additional sulfate source as well as fissile nature with multiple lengthwise cracks. ICP tests revealed time-resolved concentration trends in produced brine and reactive fluids that in turn complemented the pre-/post-reaction SEM-EDS observations.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
idpflex: Analysis of Intrinsically Disordered Proteins by Comparing Simulations to Small Angle Scattering Experiments
It is estimated that about 30% of the eucariotic proteome consists of intrinsically dis-ordered proteins (IDP’s), yet their presence in public structural databases is severely underrepresented. IDP’s adopt heterogeneous inter-converting conformations with similar probabilities, preventing resolution of structures with X-Ray diffraction techniques. An alternative technique with wide application on IDP systems is small angle scattering(SAS). SAS can measure average structural features of IDP’s when in vitro solution, or even at conditions mimicking protein concentrations found in the cell’s cytoplasm.
97 MATHEMATICS AND COMPUTING↗
Characterization of the host–guest complex of a curcumin analog with β-cyclodextrin and β-cyclodextrin–gemini surfactant and evaluation of its anticancer activity
Background: Curcumin analogs, including the novel compound NC 2067, are potent cytotoxic agents that suffer from poor solubility, and hence, low bioavailability. Cyclodextrin-based carriers can be used to encapsulate such agents. In order to understand the interaction between the two molecules, the physicochemical properties of the host–guest complexes of NC 2067 with β-cyclodextrin (CD) or β-cyclodextrin–gemini surfactant (CDgemini surfactant) were investigated for the first time. Moreover, possible supramolecular structures were examined in order to aid the development of new drug delivery systems. Furthermore, the in vitro anticancer activity of the complex of NC 2067 with CDgemini surfactant nanoparticles was demonstrated in the A375 melanoma cell line. Methods: Physicochemical properties of the complexes formed of NC 2067 with CD or CDgemini surfactant were investigated by synchrotron-based powder X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. Synchrotron-based small- and wide-angle X-ray scattering and size measurements were employed to assess the supramolecular morphology of the complex formed by NC 2067 with CDgemini surfactant. Lastly, the in vitro cell toxicity of the formulations toward A375 melanoma cells at various drug-to-carrier mole ratios were measured by cell viability assay. Results: Physical mixtures of NC 2067 and CD or CDgemini surfactant showed characteristics of the individual components, whereas the complex of NC 2067 and CD or CDgemini surfactant presented new structural features, supporting the formation of the host–guest complexes. Complexes of NC 2067 with CDgemini surfactants formed nanoparticles having sizes of 100–200 nm. NC 2067 retained its anticancer activity in the complex with CDgemini surfactant for different drug-to-carrier mole ratios, with an IC 50 (half-maximal inhibitory concentration) value comparable to that for NC 2067 without the carrier. Conclusion: The formation of host–guest complexes of NC 2067 with CD or CDgemini surfactant has been confirmed and hence the CDgemini surfactant shows good potential to be used as a delivery system for anticancer agents.
60 APPLIED LIFE SCIENCES↗
Business Case Analysis of Real Green Building Systems, LLC Technologies
Real Green Building Systems, LLC offers environmentally friendly home designs with five synergistic systems: plumbing-based fire protection, solar thermal heating and domestic hot water, solar electricity, and recycled water. This home design fits with the green construction movement in the United States that has developed to the point where 20 percent of all newly built homes last year were “green,” with an overall $25B market value. The market is expected to grow to between 29% and 38% of new U.S. homes by 2016. Generally, materials and construction costs are somewhat higher (five to ten percent) for green homes, but some localities offer rebates form the state or utility to help offset this. Structural features that are typical include tightly insulated walls to prevent air escape, insulated foundations, and windows designed to capture heat. Other add-on systems include solar or geothermal heating or cooling, and solar electric. A mechanical air exchange system may be needed to ensure good air quality given the tight nature of the house. A green home is desirable to buyers who are looking to save utility bills or reduce dependence on the grid. Often buyers are at or nearing retirement, and such a home can reduce volatility of energy costs long term. Owners may need education on the systems to feel comfortable with the relatively novel active technologies. Passive systems such as thick walls with better insulation need no maintenance or training, and can be quiet, medically safer, and more comfortable. The resale value of a green home appears to be somewhat higher than conventional homes. California data suggest a premium of about nine percent on green home sales prices. One of the key differences in RGBS homes is the fully insulated, fire-protected multi-purpose room instead of a garage. A “garage” in normal houses is not suitable for uses other than storage and parking vehicles. But RGBS designs this area to be conditioned floor space, equivalent to the rest of the home with the only difference being an overhead door. In fact, most home owners do not use a garage to store their car—a recent study showed that about 75 percent of garages are used for other purposes. This is explicitly recognized in the RGBS design, with the conditioned space made fully functional for all uses. A key benefit of this is also that the space can be counted as living space for appraisal purposes, which leads to a lower cost per square foot for the home in addition to increased functionality.
14 SOLAR ENERGY↗
New Carbon-Based Porous Materials with Increased Heats of Adsorption for Hydrogen Storage
Hydrogen fuel cell vehicles are a promising alternative to internal combustion engines that burn gasoline. A significant challenge in developing fuel cell vehicles is to store enough hydrogen on-board to allow the same driving range as current vehicles. One option for storing hydrogen on vehicles is to use tanks filled with porous materials that act as “sponges” to take up large quantities of hydrogen without the need for extremely high pressures. The materials must meet many requirements to make this possible. This project aimed to develop two related classes of porous materials to meet these requirements. All materials were synthesized from molecular constituents in a building-block approach, which allows for the creation of an incredibly wide variety of materials in a tailorable fashion. The materials have extremely high surface areas, to provide many locations for hydrogen to adsorb. In addition, they were designed to contain cations that create large electric fields to bind hydrogen strongly but not too strongly. Molecular modeling played a key role as a guide to experiment throughout the project. A major accomplishment of the project was the development of a material with record hydrogen uptake at cryogenic temperatures. Although the ultimate goal was materials that adsorb large quantities of hydrogen at room temperature, this achievement at cryogenic temperatures is an important step in the right direction. In addition, there is significant interest in applications at these temperatures. The hydrogen uptake, measured independently at NREL was 8.0 wt %. This is, to the best of our knowledge, the highest validated excess hydrogen uptake reported to date at 77 K. This material was originally sketched on paper based on a hypothesis that extended framework struts would yield materials with excellent hydrogen storage properties. However, before starting the synthesis, we used molecular modeling to assess the performance of the material for hydrogen uptake. Only after modeling suggested record-breaking hydrogen uptake at 77 K did we proceed to synthesize, characterize, and test the material, ultimately yielding experimental results that agreed closely with predictions that were made before the material was synthesized. We also synthesized, characterized, and computationally simulated the behavior of two new materials displaying the highest experimental Brunauer$-$Emmett$-$Teller (BET) surface areas of any porous materials reported to date (~7000 m 2 /g). Key to evacuating the initially solvent-filled materials without pore collapse, and thereby accessing the ultrahigh areas, was the use of a supercritical CO 2 activation technique developed by our team. In our efforts to increase the hydrogen binding energy, we developed the first examples of “zwitterionic” metal-organic frameworks (MOFs). The two structures feature zwitterionic characteristics arising from N-heterocyclic azolium groups in the linkers and negatively charged Zn 2 (CO 2 ) 5 nodes. These groups interact strongly with the H 2 quadrupole. High initial isosteric heats of adsorption for hydrogen were measured at low H 2 loading. Simulations were used to determine the H 2 binding sites, and results were compared with inelastic neutron scattering. In addition to MOFs, the project produced a variety of related materials known as porous organic frameworks (POFs), including robust catechol-functionalized POFs with tunable porosities and degrees of functionalization. Post-synthesis metalation was readily carried out with a wide range of metal precursors (Cu II , Mg II , and Mn II salts and complexes), resulting in metalated POFs with enhanced heats of hydrogen adsorption compared to the starting nonmetalated materials. Isosteric heats of adsorption as high as 9.6 kJ/mol were observed, compared to typical values around 5 kJ/mol in unfunctionalized MOFs and POFs. Modeling played an important role throughout the project. For example, we used molecular simulations to determine that the optimal isosteric heat of adsorption (Q st ) for maximum hydrogen delivery using MOFs is approximately 20 kJ/mol. If the heat of adsorption is too low, little hydrogen is adsorbed. If the heat of adsorption is too high, it is difficult to recover the hydrogen at the desorption pressure. The results supported the major premise of this project that increasing Q st for MOFs with large surface areas is required to attain current hydrogen storage targets in terms of deliverable capacity.
08 HYDROGEN↗
Spectroscopy of Charge Carriers and Traps in Field-Doped Single Crystal Organic Semiconductors
The proposed research aims to achieve quantitative, molecular level understanding of charge carriers and traps in field-doped crystalline organic semiconductors via in situ linear and nonlinear optical spectroscopy, in conjunction with transport measurements and molecular/crystal engineering. Organic semiconductors are emerging as viable materials for low-cost electronics and optoelectronics, such as organic photovoltaics (OPV), organic field effect transistors (OFETs), and organic light emitting diodes (OLEDs). Despite extensive studies spanning many decades, a clear understanding of the nature of charge carriers in organic semiconductors is still lacking. It is generally appreciated that polaron formation and charge carrier trapping are two hallmarks associated with electrical transport in organic semiconductors; the former results from the low dielectric constants and weak intermolecular electronic overlap while the latter can be attributed to the prevalence of structural disorder. These properties have lead to the common observation of low charge carrier mobilities, e.g., in the range of 10-5 - 10-3 cm2/Vs, particularly at low carrier concentrations. However, there is also growing evidence that charge carrier mobility approaching those of inorganic semiconductors and metals can exist in some crystalline organic semiconductors, such as pentacene, tetracene and rubrene. A particularly striking example is single crystal rubrene (Figure 1), in which hole mobilities well above 10 cm2/Vs have been observed in OFETs operating at room temperature. Temperature dependent transport and spectroscopic measurements both revealed evidence of free carriers in rubrene. Outstanding questions are: what are the structural features and physical properties that make rubrene so unique? How do we establish fundamental design principles for the development of other organic semiconductors of high mobility? These questions are critically important but not comprehensive, as the nature of charge carriers is known to evolve as the carrier concentration increases, due to the presence of intrinsic disorder in organic semiconductors. Thus, a complementary question is: how does the nature of charge transport change as a function of carrier concentration?
36 MATERIALS SCIENCE↗
Bioenergetics of halophiles
In the last grant period we explored the Na+ binding site of the recently discovered light-driven sodium ion pump. The rationale was that comparison of this novel system to the similar proton pumps and chloride ion pumps would reveal the amazingly (and unexpectedly) wide variety of structural features that govern conversion of light-energy into biologically useful transmembrane gradients and thus production of biomass. A thorough description of this system would establish the basis for continuing our funded research on these proteins.
59 BASIC BIOLOGICAL SCIENCES↗
Capturing the Complexity of Additively Manufactured Microstructures
The underlying mechanisms and kinetics controlling damage nucleation and growth as a function of material microstructure and loading paths are discussed. These experiments indicate that structural features such as grain boundaries, grain size distribution, grain morphology crystallographic texture are all factors that influence mechanical behavior.
36 MATERIALS SCIENCE↗
Experimental and Computational Investigation of High Entropy Alloys for Elevated-Temperature Applications
To create and design novel structural materials with enhanced creep-resistance, fundamental studies have been conducted on high-entropy alloys (HEAs), using (1) thermodynamic calculations, (2) mechanical tests, (3) neutron diffraction, (4) characterization techniques, and (5) crystal-plasticity finite-element modeling (CPFEM), to explore future candidates for next-generation power plants. All the constituent binary and ternary systems of the Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr-Fe-Ni systems were thermodynamically modeled within the whole composition range. Comparisons between the calculated phase diagrams and literature data are in good agreement. Seven types of HEAs were fabricated from Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr-Fe-Ni systems. The Al x CrCuFeMnNi HEAs have disordered [face-centered cubic (FCC) + body-centered cubic (BCC)] crystal structures, not FCC or BCC single structure. Excessive alloying of the Al element results in the change of both microstructural and mechanical properties in Al x CoCrFeNi HEAs. There are mainly three structural features in Al x CoCrFeNi: (1) the morphology, (2) the volume fractions of the constitute phases, and (3) existing temperatures of all six phases. After homogenization, the Al 0.3 CoCrFeNi material is a pure FCC solid solution. After aging at 700 °C for 500 hours, the optimal microstructure combinations, the FCC matrix, needle-like B2 phase within grains, and granular σ phase along grain boundary, is achieved for Al 0.3 CoCrFeNi. The cold-rolling process is utilized to reduce the grain size of Al 0.1 CoCrFeNi and Al 0.3 CoCrFeNi. The chemical elemental partitioning of FCC, BCC, B2, and σphases at different temperatures, before and after mechanical tests, in Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr-Fe-Ni systems are quantitatively characterized by both synchrotron X-ray diffraction, neutron diffraction with levitation, scanning electron microscopy (SEM), advanced atom probe tomography (APT), and transmission electron microscopy (TEM). In-situ neutron diffraction experiments were conducted to study the strengthening effect of B2 phase on tensile properties of Al 0.3 CoCrFeNi HEAs directly. The results shows the creep behavior of Al 0.3 CoCrFeNi is superior to conventional alloys, and the heat treatment introduces secondary B2 phase into the FCC matrix, which increase the yielding strength, decrease the ductility, diminish the serrated flow during compression tests at high temperatures. In summary, the outcomes of the development of the HEAs with creep resistance include: (1) Suitable candidates, for the application to boilers and steam and gas turbines at temperatures above 760 °C and a stress of 35 MPa. (2) Fundamental understanding on the precipitate stability and deformation mechanisms of both single-phase and precipitate-strengthened alloys at room and elevated temperatures, and (3) The demonstration of an integrated approach, coupling modeling [thermodynamic calculations and crystal-plasticity finite-element modeling (CPFEM)] and focused experiments, to identify HEAs that outperform conventional alloys for high-temperature applications, which will be applicable for the discovery and development of other high-temperature materials in the power-generating industry.
36 MATERIALS SCIENCE↗
New approaches for metabolomics by mass spectrometry
Small molecules constitute a large part of the world around us, including fossil and some renewable energy sources. Solar energy harvested by plants and bacteria is converted into energy rich small molecules on a massive scale. Some of the worst contaminants of the environment and compounds of interest for national security also fall in the category of small molecules. The development of large scale metabolomic analysis methods lags behind the state of the art established for genomics and proteomics. This is commonly attributed to the diversity of molecular classes included in a metabolome. Unlike nucleic acids and proteins, metabolites do not have standard building blocks, and, as a result, their molecular properties exhibit a wide spectrum. This impedes the development of dedicated separation and spectroscopic methods. Mass spectrometry (MS) is a strong contender in the quest for a quantitative analytical tool with extensive metabolite coverage. Although various MS-based techniques are emerging for metabolomics, many of these approaches include extensive sample preparation that make large scale studies resource intensive and slow. New ionization methods are redefining the range of analytical problems that can be solved using MS. This project developed new approaches for the direct analysis of small molecules in unprocessed samples, as well as pushed the limits of ultratrace analysis in volume limited complex samples. The projects resulted in techniques that enabled metabolomics investigations with enhanced molecular coverage, as well as the study of cellular response to stimuli on a single cell level. Effectively individual cells became reaction vessels, where we followed the response of a complex biological system to external perturbation. We established two new analytical platforms for the direct study of metabolic changes in cells and tissues following external perturbation. For this purpose we developed a novel technique, laser ablation electrospray ionization (LAESI), for metabolite profiling of functioning cells and tissues. The technique was based on microscopic sampling of biological specimens by mid-infrared laser ablation followed by electrospray ionization of the plume and MS analysis. The two main shortcomings of this technique had been limited specificity due to the lack of a separation step, and limited molecular coverage, especially for nonpolar chemical species. To improve specificity and the coverage of the metabolome, we implemented the LAESI ion source on a mass spectrometer with ion mobility separation (IMS). In this system, the gas phase ions produced by the LAESI source were first sorted according to their collisional cross sections in a mobility cell. These separated ion packets were then subjected to MS analysis. By combining the atmospheric pressure ionization with IMS, we improved the metabolite coverage. Further enhancement of the non-polar metabolite coverage resulted from the combination of laser ablation with vacuum UV irradiation of the ablation plume. Our results indicated that this new ionization modality provided improved detection for neutral and non-polar compounds. Based on rapid progress in photonics, we had introduced another novel ion source that utilized the interaction of a laser pulse with silicon nanopost arrays (NAPA). In these nanophotonic ion sources, the structural features were commensurate with the wavelength of the laser light. The enhanced interaction resulted in high ion yields. This ultrasensitive analytical platform enabled the MS analysis of single yeast cells. We extended these NAPA studies from yeast to other microorganisms, including green algae (Chlamydomonas reinhardtii) that captured energy from sunlight on a massive scale. Combining cellular perturbations, e.g., through environmental changes, with the newly developed single cell analysis methods enabled us to follow dynamic changes induced in the cells. In effect, we were able to use individual cells as a “laboratory,” and approached the long-standing goal of establishing a “lab-in-a-cell.” Model systems for these studies included cells of cyanobacteria (Anabaena), yeast (Saccharomyces cerevisiae), green algae (C. reinhardtii) and Arabidopsis thaliana.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Magnetostrictive Cold Spray Sensor Feasibility Assessment
Ultrasound sensors and inspection systems are frequently used to generate acoustic waves in metal structures capable of detecting and characterizing cracks, pits, erosion, inclusions, weld anomalies, and other material and structural features. One significant problem with piezoelectric transducers is the difficulty to achieve good coupling between the transducer and the surface being examined. This is particularly true in harsh conditions with high temperatures, cyclical hot and cold temperatures, highly radioactive fields found near nuclear reactors or spent nuclear fuel, caustic or corrosive fluids, and other extreme environmental conditions, as well as in long-term monitoring applications where repair or replacement of the sensor is difficult or expensive. Typically, coupling between the surface and the transducer is achieved with water, gel, grease, viscous shear coupling material, or pressure, which might not be possible or appropriate for long-term applications in which the impedance -matching materials wear away, evaporate, or simply stop functioning due to changes in surface conditions. Fluid couplings can evaporate or drain away from the transducer-substrate interface; glue- based couplings may foul or fail and are notoriously unreliable at high temperatures and in radioactive environments. This work explores the behavior of a magnetostrictive cold-spray patch that is metallurgically bonded to a stainless steel inspection target surface, and compares it to the performance of a standard adhesively-bonded ferrous-cobalt magnetostrictive strip solution. Cold-spray is a coating process where 10 –100 micron diameter powdered metal is accelerated to Mach 2 to Mach 3 (2–3 × speed of sound) and impacted on the surface to be coated. Each powder particle forms a kinetic bond with the substrate or other coating particles to produce a metallurgically bonded layer. If the powder is nickel or cobalt with high magnetostrictive coefficients, this surface can serve as the base of a magnetostrictive sensor suitable for crack or pitting-damage inspection and monitoring that is not subject to temporal or environmental degradation.
47 OTHER INSTRUMENTATION↗
Mid-Atlantic U.S. Offshore Carbon Storage Resource Assessment Project (Final Technical Report)
The greatest potential for carbon storage in the northeastern United States lies in the offshore geologic formations comprising the outer continental shelf (Monteverde et al., 2011). Offshore storage can be linked to large point-sources of carbon dioxide (CO 2 ) while avoiding many of the logistical difficulties and potential risks encountered when siting onshore projects, especially in densely populated areas of the East Coast. Offshore CO 2 storage assessment and research in the United States is underway to address uncertainty in potential storage resources, particularly in the mid- and north-Atlantic offshore area. Given the current knowledge base and access to publicly available data, the objectives of the Mid-Atlantic U.S. Offshore Carbon Storage Resource Assessment Project (MAOCSRAP) were fourfold: (1) complete a systematic carbon storage resource assessment of the mid-Atlantic offshore coastal region from the Georges Bank Basin (GBB) through the Long Island Platform (LIP) to the southern Baltimore Canyon Trough (BCT); (2) define key input parameters to reduce uncertainty for offshore storage resource and efficiency estimates; (3) perform a preliminary assessment of risk factors, uncertainties, and data gaps; and (4) engage industry and regulatory stakeholders through development of a Road Map to assist future project planning and implementation. The MAOCSRAP project has compiled, inventoried, and assimilated various publicly available data sets to provide a strong technical basis on which future carbon storage studies and applications can be built. The knowledge infrastructure necessary to support the development of full-scale offshore carbon storage include: Defining the geologic characteristics of candidate storage sites (Chapter 2). Using existing seismic data to better define the continuity of the storage zones and seals (Chapter 3). Cataloguing the hydrogeologic properties of mid-Atlantic offshore storage sites (Chapter 4). Calculating prospective CO 2 storage resources using net effective pore volumes and fluid displacement properties specific to offshore lithologies (Chapter 5). Examining risk factors related to offshore storage (Chapter 6). Communicating with industry and other stakeholders about the future prospects for offshore storage (Chapter 7). Ensuring technology transfer to industry and other stakeholders (Chapter 8). Led by Battelle, this project was conducted by public and private entities with expertise in offshore geology and resources for the study region, including state geological surveys of Delaware, Maryland, and Pennsylvania; United States Geological Survey-Woods Hole Coastal and Marine Science Center and Haifa University; Rutgers University; Harvard University; and Lamont-Doherty Earth Observatory (LDEO) at Columbia University. The storage resource assessment was completed for a broad region offshore of the U.S. East Coast, from Massachusetts to Virginia. The results include high-level storage resource estimates for areas not previously characterized and improved storage resource estimates for geographically expansive portions of offshore geologic units. Results of the project provide a foundation for developing CO 2 storage along offshore areas of the mid-Atlantic United States. A combination of information was used to provide confidence in project results. Key findings of the major project tasks are summarized as follows. Subsurface Data Analysis: Legacy seismic, well-log, core, and biostratigraphic data were digitized, reprocessed, and analyzed using modern techniques, augmenting previous characterization efforts. The sequence stratigraphic framework for the Cretaceous and Jurassic strata was developed by correlating well-log depositional sequences to seismic reflectors identified in the BCT, LIP, and GBB. The integration of well-log stratigraphy with seismic stratigraphy and petrophysical analysis helped to identify and map potential storage zones within sequences of the Logan Canyon (LC), Missisauga, and Mohawk formations, as well as the regionally extensive caprock comprised of the Dawson Canyon shale. Approximately 4,000 kilometers (km) of seismic data was reprocessed to create a structural framework that was used to tie together all available well data, constrain sequence stratigraphic interpretations, and make regional assessments of offshore carbon storage resources. Prospective storage resource estimates were 150 to 1136 megatons (Mt) for the combined storage zones. This suggests mid-Atlantic U.S. offshore formations can store decades of CO 2 from industrial sources in the region. Preliminary local reservoir simulations suggest that injection rates of 1 Mt CO 2 /year may be sustained for 30 years in single injection wells in the BCT. Advanced geologic modeling and new data acquisition are needed to address data gaps and advance carbon capture and storage (CCS) in key offshore areas selected for further investigation. Offshore Risk Factors: Offshore geologic risk factors include soft sediment deformation, unit continuity, sedimentological and structural features, seismicity and hydrates. CO 2 storage risks include inadequate seals, migration/leakage, and chemical interactions leading to decreased storage. Sensitive habitats, environmental impacts, disturbance to seafloor, and other risks need to be identified in advance of project activities and integrated into detailed mitigation plans for all project phases. Stakeholder Engagement: Input and participation from government, industry, and environmental groups provided input into the Road Map and address next steps needed for project deployment. Early engagement and ongoing communication, as well as policy framework development, is key to large-scale deployment of CCS. Next Steps: This project represents an important first step by completing a high-level CO 2 storage resource assessment and building the knowledge infrastructure necessary to improve quantitative storage resource estimates. The data sets that have been curated under this project provide an opportunity to conduct research and development (R&D) needed to address data gaps and reduce risk and uncertainty. Offshore characterization and validation strategies that are systematically designed to provide data and infrastructure that can be upscaled to meet commercial requirements could be developed off of this foundation.
29 ENERGY PLANNING, POLICY, AND ECONOMY↗
Molecule Origins of Dipolar Character in Excited Electronic States
The molecular level origins for symmetry breaking in the excited state of symmetrical quadrupolar molecules, particularly in polar solvents, was investigated using time-dependent density functional theory approaches. Molecules of the form ADA (A/D electron accepting/donating respectively), have been shown to break their symmetry upon excitation, producing an intramolecular charge transfer event and permanent dipole. Current research indicates that polar solvents stabilize the charge transfer event thereby producing asymmetrical solvent dynamics on opposite ends of the molecules. In this work key structural features of the molecule were identified including (1) incorporation of cyano groups, (2) rotation of grafted phenyl rings, and (3) the length of the conjugated R group chain. More specifically, incorporation of cyano groups appears to decrease the magnitude of the dipole in the excited state, thereby indicating that solvent interactions at these groups do not stabilize the charge transfer. While the rotation of the phenyl groups appears to be necessary to break the symmetry of the excited state in the molecule.
36 MATERIALS SCIENCE↗
Pahute Mesa-Oasis Valley Hydrostratigraphic Framework Model for Corrective Action Units 101 and 102: Central and Western Pahute Mesa, Nye County, Nevada (Rev. 0)
A new, revised three-dimensional (3-D) hydrostratigraphic framework model (HFM) for the Central and Western Pahute Mesa Corrective Action Units 101 and 102 was completed in 2019. The initial (Phase I) model was completed in 2002 and was documented in A Hydrostratigraphic Model and Alternatives for the Groundwater Flow and Contaminant Transport Model of Corrective Action Units 101 and 102: Central and Western Pahute Mesa, Nye County, Nevada (BN, 2002). Subsequent flow and transport modeling revealed the need to collect additional data to reduce uncertainties. The Phase II data collection and characterization effort included extensive well drilling and testing activities, and rebuilding of the Phase I 3-D HFM, resulting in the Phase II HFM (NSTec, 2014). Further drilling (Well ER-20-12), data collection, and interpretive work (e.g., Thirsty Canyon Lineament [Wurtz and Day, 2018]) were incorporated into the Pahute Mesa-Oasis Valley (PM-OV) HFM. The PM-OV HFM incorporates the area of interest from the Phase II HFM and adds additional areas, primarily to the north and west with minor additions to the south and east. The new, expanded area matches the PM-OV groundwater basin as defined in Fenelon et al. (2016) and includes Pahute Mesa, a former nuclear testing area at the Nevada National Security Site; and Oasis Valley, a groundwater discharge area downgradient from contaminant source areas on Pahute Mesa. The data and information necessary to build the PM-OV HFM are provided in Navarro (2019). The PM-OV HFM will be used by hydrologic modelers who are tasked with developing a model to determine how contaminants are transported by groundwater flow in an area of complex geology. The model area is large (more than 6,250 square kilometers) and geologically complex, including Paleozoic- to Mesozoic-age structures (e.g., thrust faults, Thirsty Canyon Lineament), at least seven Tertiary-age calderas, several intrusive bodies, and many relatively recent basin-and-range normal faults. Investigators from the U.S. Geological Survey; National Security Technologies, LLC; National Laboratories; and U.S. Department of Energy contractors have organized the more than 300 volcanic units and other rocks in the model area into 77 hydrostratigraphic units (HSUs). The volcanic rocks are subdivided into 42 aquifers, 11 confining units, and 9 composite units (containing both aquifer and confining unit rocks). The underlying pre-Tertiary rocks were divided into 5 HSUs, comprising 2 aquifers and 3 confining units. The model also includes 1 alluvial aquifer unit, 8 intrusive confining units, and 1 granite confining unit. The model depicts the thickness, extent, and geometric relationships of these HSUs (“layers” in the model) along with all the major structural features that control them, including calderas and faults. The most substantive differences between the Phase II HFM and the PM-OVHFM include (1) addition of the new data and resulting revised interpretations from the additional area encompassed by the PM-OV groundwater basin; (2) incorporation of 16 new faults; (3) 12 boreholes from the northern extension; (4) 2 additional caldera-collapse collars; and (5) correlation of the simulated faulting and hydrostratigraphy in the eastern part of the model domain with the delineations represented in the neighboring Rainier Mesa-Shoshone Mountain HFM-Prime and Yucca Flat-Climax Mine HFM. All PM-OV HFM delineations were based on published and unpublished data from geophysical investigations, surface geologic maps, and drill-hole records. Phase II approached model uncertainty using the model-building software to test model configurations and hydrologic consequences using a range of values for parameters such as fault offset amounts and HSU elevations. The PM-OV HFM expands on this approach to encompass the entire PM-OV groundwater basin.
54 ENVIRONMENTAL SCIENCES↗