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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Impact of Drought Stress on Sorghum bicolor Yield, Deconstruction, and Microbial Conversion Determined in a Feedstocks-to-Fuels Pipeline

Sorghum is an attractive feedstock for biobased fuel and chemical production because it is familiar to farmers, naturally drought tolerant, and versatile as a food, feed, and fuel crop. Although sorghum is a promising feedstock, particularly in regions that experience drought stress, little is known about how drought conditions impact the ease of conversion of sorghum to fuels and products. This study combines agronomic field trials with a high-throughput experimental pipeline to explore the field performance and liquid biofuel (bisabolene) yields resulting from three sorghum types (photosensitive forage sorghum, optimized grain sorghum, and drought-resistant grain sorghum) grown under pre- and postflowering water limitations in two different California locations. Multiple drought treatments are compared to the control, as the timing (preflowering versus postflowering) of drought stress elicits different survival strategies and corresponding impacts on yield and composition. Forage-type sorghum maintained the highest biomass yields across all irrigation conditions and locations. Glucose and xylose yields resulting from ionic liquid pretreatment and enzymatic saccharification were not significantly impacted by irrigation treatments but differed by location and genotype. However, Rhodosporidium toruloides grown on the resulting plant hydrolysates unexpectedly produced higher titers of bisabolene for drought-stressed sorghum samples regardless of genotype.

09 BIOMASS FUELS↗
DOE OSTI2016

Deconstructing Biomass [part of The frontiers of energy]

Great strides have been made over the past century in our ability to harness energy sources, leading to profound transformations — both good and bad — in society. Looking at the energy system of today, it is clear that meeting the energy needs of the world now and in the years to come requires the concerted efforts of many different actors across a range of technologies and approaches. In this Feature, ten leading experts in energy research share their vision of what challenges their respective fields need to address in the coming decades. The issues being faced are diverse and multifaceted, from the search for better materials for fuels, to the design of energy policy and markets for the developing world. However, a common theme emerges: changes to adapt and improve our energy system are greatly needed. As a result, by improving our mutual understanding of the issues faced by each area of energy research, these changes can happen more smoothly, efficiently and rapidly.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2025

Recent advances in enzyme engineering for improved deconstruction of poly(ethylene terephthalate) (PET) plastics

In the last ~20 years, a multitude of natural enzymes have been discovered that can catalyze the breakdown of the common plastic poly(ethylene terephthalate) (PET). While enzymatic PET recycling is an attractive alternative end-of-life route for this waste plastic, the enzymes are not yet optimized for efficient and economical industrial use. Here, we discuss recent advances in engineering these PET-degrading enzymes, which include PET, bis(2-hydroxyethyl) terephthalate (BHET), and 2-hydroxyethyl terephthalic acid (MHET) hydrolases, toward industrially-relevant engineering goals. We place emphasis on trends from past efforts in rational and semi-rational design and emerging areas in directed evolution/high throughput screening and computational design for engineering these enzymes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Synchrotron-based X-ray fluorescence microscopy enables multiscale spatial visualization of ions involved in fungal lignocellulose deconstruction

Ions play an important role in the growth and development of filamentous fungi, particularly in the fungal decay process of lignocellulose materials. The role of ions in wood degradation, and more broadly fungal metabolism, have implications for diverse research disciplines ranging from plant pathology and forest ecology, to wood protection. Despite the importance of ions in both enzymatic and non-enzymatic fungal decay mechanisms, the spatial distribution of ions in wood and fungal hyphae during decay is not known. Here we employ synchrotron based X-ray fluorescence microscopy (XFM) to map physiologically relevant ions, such as K, Ca, Mn, Fe, and Zn, in wood being decayed by the model brown rot fungus Serpula lacrymans . Two-dimensional XFM maps were obtained to study the ion spatial distributions from mm to submicron length scales in wood and hyphae. Three-dimensional ion volume reconstructions with submicron spatial resolution were also acquired of wood cell walls and fungal hyphae, and an estimation of oxalate concentration at the microscale was made. Results show that the fungus actively transports some ions, such as Fe, into the wood and controls the distribution of ions at both the bulk wood and cellular length scales. Within the fungal hyphae, ion volume reconstructions show inhomogeneous ion distributions at the micron length scale and this localization may be indicative of both physiological status and requirements or in some cases, potentially sites associated with the initiation of metal-catalyzed wood degradation. Finally, these measurements illustrate how synchrotron based XFM is uniquely qualified for probing the role of ions in the growth and metabolic processes of filamentous fungi.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Pyrolysis reaction networks for lignin model compounds: unraveling thermal deconstruction of β-O-4 and α-O-4 compounds

Although lignin is one of the main components of biomass, its pyrolysis chemistry is not well understood due to complex heterogeneity. To gain insights into this chemistry, the pyrolysis of seven lignin model compounds (five ..beta..-O-4 and two ..alpha..-O-4 linked molecules) was investigated in a micropyrolyzer connected to GC-MS/FID. According to quantitative product mole balance for the reaction networks, concerted retro-ene fragmentation and homolytic dissociation were strongly suggested as the initial reaction step for ..beta..-O-4 compounds and ..alpha..-O-4 compounds, respectively. The difference in reaction pathway between compounds with different linkages was believed to result from thermodynamics of the radical initiation. The rate constants for the different reaction pathways were predicted from ab initio density functional theory calculations and pre-exponential literature values. The computational findings were consistent with the experiment results, further supporting the different pyrolysis mechanisms for the ..beta..-ether linked and ..alpha..-ether linked compounds. A combination of the two pathways from the dimeric model compounds was able to describe qualitatively the pyrolysis of a trimeric lignin model compound containing both ..beta..-O-4 and ..alpha..-O-4 linkages.

09 BIOMASS FUELS↗
DOE OSTI2020

Ammonia-salt solvent promotes cellulosic biomass deconstruction under ambient pretreatment conditions to enable rapid soluble sugar production at ultra-low enzyme loadings

In this paper, we report a novel ammonia : ammonium salt solvent based pretreatment process that can rapidly dissolve crystalline cellulose into solution and eventually produce highly amorphous cellulose under near-ambient conditions. Pre-activating the cellulose I allomorph to its ammonia–cellulose swollen complex (or cellulose III allomorph) at ambient temperatures facilitated rapid dissolution of the pre-activated cellulose in the ammonia-salt solvent ( i.e. , ammonium thiocyanate salt dissolved in liquid ammonia) at ambient pressures. For the first time in reported literature, we used time-resolved in situ neutron scattering methods to characterize the cellulose polymorphs structural modification and understand the mechanism of crystalline cellulose dissolution into a ‘molecular’ solution in real-time using ammonia-salt solvents. We also used molecular dynamics simulations to provide insight into solvent interactions that non-covalently disrupted the cellulose hydrogen-bonding network and understand how such solvents are able to rapidly and fully dissolve pre-activated cellulose III. Importantly, the regenerated amorphous cellulose recovered after pretreatment was shown to require nearly ~50-fold lesser cellulolytic enzyme usage compared to native crystalline cellulose I allomorph for achieving near-complete hydrolytic conversion into soluble sugars. Lastly, we provide proof-of-concept results to further showcase how such ammonia-salt solvents can pretreat and fractionate lignocellulosic biomass like corn stover under ambient processing conditions, while selectively co-extracting ~80–85% of total lignin, to produce a highly digestible polysaccharide-enriched feedstock for biorefinery applications. Unlike conventional ammonia-based pretreatment processes ( e.g. , Ammonia Fiber Expansion or Extractive Ammonia pretreatments), the proposed ammonia-salt process can operate at near-ambient conditions to greatly reduce the pressure/temperature severity necessary for conducting effective ammonia-based pretreatments on lignocellulose.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Nanomechanics of cellulose deformation reveal molecular defects that facilitate natural deconstruction

Significance Cellulose plays an important role as a structural polymer for natural material applications and as a source of sugars for production of renewable fuels and chemicals. Previously, kink defects have been observed in isolated cellulose nanofibrils. In this work, we provide direct evidence that these defects can be induced by mechanical deformation and are often accompanied by molecular-level bond breakages that are exploited by cellulase enzymes as initiation sites for processive hydrolysis. This relationship between mechanical stress and molecular defect formation has likely played a role in the evolution of both plants and natural cellulolytic enzyme systems. An improved understanding of these principles provides insight for the development of advanced cellulose utilization and processing technologies.

09 BIOMASS FUELS↗
DOE OSTI2023

Deconstructing magnetization noise: Degeneracies, phases, and mobile fractionalized excitations in tetris artificial spin ice

Direct detection of spontaneous spin fluctuations, or “magnetization noise,” is emerging as a powerful means of revealing and studying magnetic excitations in both natural and artificial frustrated magnets. Depending on the lattice and nature of the frustration, these excitations can often be described as fractionalized quasiparticles possessing an effective magnetic charge. Here, by combining ultrasensitive optical detection of thermodynamic magnetization noise with Monte Carlo simulations, we reveal emergent regimes of magnetic excitations in artificial “tetris ice.” A marked increase of the intrinsic noise at certain applied magnetic fields heralds the spontaneous proliferation of fractionalized excitations, which can diffuse independently, without cost in energy, along specific quasi-1D spin chains in the tetris ice lattice.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Deconstructing dynamics of symmetry breaking

The Kibble–Zurek mechanism (KZM) successfully predicts the density of topological defects deposited by the phase transitions, but it is not clear why. Its key conjecture is that, near the critical point of the second-order phase transition, critical slowing down will result in a period when the system is too sluggish to follow the potential that is changing faster than its reaction time. The correlation length at the freeze-out instant $\hat{t}$ when the order parameter catches up with the posttransition broken symmetry configuration is then decisive, determining when the mosaic of broken symmetry domains locks in topological defects. To understand why the KZM works so well, we analyze the Landau–Ginzburg model and show why temporal evolution of the order parameter plays such a key role. In conclusion, the analytical solutions we obtain suggest experimentally accessible observables that can shed light on symmetry-breaking dynamics while testing the conjecture on which the KZM is based.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

DECONSTRUCTING THERMAL SUNYAEV–ZEL’DOVICH—GRAVITATIONAL LENSING CROSS-CORRELATIONS: IMPLICATIONS FOR THE INTRACLUSTER MEDIUM

Recent first detections of the cross-correlation of the thermal Sunyaev–Zel’dovich (tSZ) signal in Planck cosmic microwave background (CMB) temperature maps with gravitational lensing maps inferred from the Planck CMB data and the CFHTLenS galaxy survey provide new probes of the relationship between baryons and dark matter. Using cosmological hydrodynamics simulations, we show that these cross-correlation signals are dominated by contributions from hot gas in the intracluster medium (ICM), rather than diffuse, unbound gas located beyond the virial radius (the “missing baryons”). Thus, these cross-correlations offer a tool with which to study the ICM over a wide range of halo masses and redshifts. In particular, we show that the tSZ—CMB lensing cross-correlation is more sensitive to gas in lower-mass, higher-redshift halos and gas at larger cluster-centric radii than the tSZ—galaxy lensing cross-correlation. Combining these measurements with primary CMB data will constrain feedback models through their signatures in the ICM pressure profile. We forecast the ability of ongoing and future experiments to constrain the parameters of a phenomenological ICM model, including the mean amplitude of the pressure–mass relation, the redshift evolution of this amplitude, and the mean outer logarithmic slope of the pressure profile. The results are promising, with ≈5%–20% precision constraints achievable with upcoming experiments, even after marginalizing over cosmological parameters.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Deconstructing laws of accessibility and facility distribution in cities

The era of the automobile has seriously degraded the quality of urban life through costly travel and visible environmental effects. A new urban planning paradigm must be at the heart of our road map for the years to come, the one where, within minutes, inhabitants can access their basic living needs by bike or by foot. In this work, we present novel insights of the interplay between the distributions of facilities and population that maximize accessibility over the existing road networks. Results in six cities reveal that travel costs could be reduced in half through redistributing facilities. In the optimal scenario, the average travel distance can be modeled as a functional form of the number of facilities and the population density. As an application of this finding, it is possible to estimate the number of facilities needed for reaching a desired average travel distance given the population distribution in a city.

42 ENGINEERING↗
DOE OSTI2025

Confocal Raman Microscopy as a Probe of Material Deconstruction in Processed Low-Density Polyethylene Particles

Confocal Raman microscopy was applied to detect structural change within individual particles of low-density polyethylene (LDPE) following chemical and electrochemical processing steps that aimed to facilitate material decomposition. A high numerical aperture (NA) oil-immersion objective enabled depth-profiling through the near surface region (20 μm–40 μm) of irregularly shaped particles with an axial spatial resolution < 2 μm estimated from measurements of instrument detection efficiency profiles. Changes in vibrational bands sensitive to polyethylene crystallinity were evident following treatments and linked to the release of low molecular weight compounds present as additives and products of processing. Effects of processing were probed by monitoring the rise of Raman scattering intensity in vibrational modes associated with polyethylene chains in a zig-zag (trans) conformation near 1128 cm –1 , 1294 cm –1 , and 1418 cm –1 , signaling chain clustering and development of organized, crystalline-like assemblies. Pristine LDPE particles displayed a uniform structure across the near surface region, while particles treated initially with chemical extractant and then further processed displayed increasingly enhanced crystallinity up to the maximum depth probed (40 μm). As a step toward measurements on ensembles of particles, least squares modeling was adapted to derive pure component spectra reflecting crystallinity change within spectral datasets. The work demonstrates high spatial resolution Raman depth-profiling for the characterization of processed polymers using a high NA immersion objective to overcome the limitations of air-objectives often used for confocal Raman microscopy.

Wahiduzzaman, Md. [Department of Chemistry and Bio↗
DOE OSTI2014

Deletion of Caldicellulosiruptor bescii CelA reveals its crucial role in the deconstruction of lignocellulosic biomass

Background: Members of the bacterial genus Caldicellulosiruptor are the most thermophilic cellulolytic organisms described to date, and have the ability to grow on lignocellulosic biomass without conventional pretreatment. Different species vary in their abilities to degrade cellulose, and the presence of CelA, a bifunctional glycoside hydrolase that contains a Family 48 and a Family 9 catalytic domain, correlates well with cellulolytic ability in members of this genus. For example, C. hydrothermalis, which does not contain a CelA homolog, or a GH48 Family or GH9 Family glycoside hydrolase, is the least cellulolytic of the Caldicellulosiruptor species so far described. C. bescii, which contains CelA and expresses it constitutively, is among the most cellulolytic. In fact, CelA is the most abundant extracellular protein produced in C. bescii. The enzyme contains two catalytic units, a Family 9A-CBM3c processive endoglucanase and a Family 48 exoglucanase, joined by two Family 3b carbohydrate-binding domains. Although there are two non-reducing end-specific Family 9 and three reducing end-specific Family 48 glycoside hydrolases (producing primarily glucose and cellobiose; and cellobiose and cellotriose, respectively) in C. bescii, CelA is the only protein that combines both enzymatic activities. Results: A deletion of the celA gene resulted in a dramatic reduction in the microorganism’s ability to grow on crystalline cellulose (Avicel) and diminished growth on lignocellulosic biomass. A comparison of the overall endoglucanase and exoglucanase activities of the mutant compared with the wild-type suggests that the loss of the endoglucanase activity provided by the GH9 family domain is perhaps compensated for by other enzymes produced by the cell. In contrast, it appears that no other enzymes in the C. bescii secretome can compensate for the loss of exoglucanase activity. The change in enzymatic activity in the celA mutant resulted in a 15-fold decrease in sugar release on Avicel compared with the parent and wild-type strains. In conclusion: The exoglucanase activity of the GH48 domain of CelA plays a major role in biomass degradation within the suite of C. bescii biomass-degrading enzymes.

09 BIOMASS FUELS↗
DOE OSTI2015

Expression of the Acidothermus cellulolyticus E1 endoglucanase in Caldicellulosiruptor bescii enhances its ability to deconstruct crystalline cellulose

The Caldicellulosiruptor bescii genome encodes a potent set of carbohydrate-active enzymes (CAZymes), found primarily as multi-domain enzymes that exhibit high cellulolytic and hemicellulolytic activity on and allow utilization of a broad range of substrates, including plant biomass without conventional pretreatment. CelA, the most abundant cellulase in the C. bescii secretome, uniquely combines a GH9 endoglucanase and a GH48 exoglucanase in one protein. The most effective commercial enzyme cocktails used in vitro to pretreat biomass are derived from fungal cellulases (cellobiohydrolases, endoglucanases and a β-d-glucosidases) that act synergistically to release sugars for microbial conversion. The C. bescii genome contains six GH5 domains in five different open reading frames. Four exist in multi-domain proteins and two as single catalytic domains. E1 is a GH5 endoglucanase reported to have high specific activity and simple architecture and is active at the growth temperature of C. bescii . E1 is an endo-1,4-β-glucanase linked to a family 2 carbohydrate-binding module shown to bind primarily to cellulosic substrates. As a result, we tested if the addition of this protein to the C. bescii secretome would improve its cellulolytic activity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗