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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 1,585 records · Page 88
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Life Cycle Assessment of Switchgrass Cellulosic Ethanol Production in the Wisconsin and Michigan Agricultural Contexts

Spatial variability in yields and greenhouse gas emissions from soils has been identified as a key source of variability in life cycle assessments (LCAs) of agricultural products such as cellulosic ethanol. This study aims to conduct an LCA of cellulosic ethanol production from switchgrass in a way that captures this spatial variability and tests results for sensitivity to using spatially averaged results. The Environment Policy Integrated Climate (EPIC) model was used to calculate switchgrass yields, greenhouse gas (GHG) emissions, and nitrogen and phosphorus emissions from crop production in southern Wisconsin and Michigan at the watershed scale. These data were combined with cellulosic ethanol production data via ammonia fiber expansion and dilute acid pretreatment methods and region-specific electricity production data into an LCA model of eight ethanol production scenarios. Standard deviations from the spatial mean yields and soil emissions were used to test the sensitivity of net energy ratio, global warming potential intensity, and eutrophication and acidification potential metrics to spatial variability. Substantial variation in the eutrophication potential was also observed when nitrogen and phosphorus emissions from soils were varied. This work illustrates the need for spatially explicit agricultural production data in the LCA of biofuels and other agricultural products.

Acidification↗
DOE OSTI2023

A streamlined approach to characterize microalgae strains for biomass productivity under dynamic climate simulation conditions

Screening microalgae strains under static light and temperature flask conditions cannot directly quantify the biomass productivities of algae growing in the dynamically fluctuating light and temperature conditions of outdoor ponds. In this effort, we describe a testing pipeline that screens for productivity under climate simulated conditions. A validated, miniaturized Laboratory Environmental Algae Pond Simulator (mini-LEAPS) photobioreactor was used to determine optimal medium salinities and biomass productivities of cold-tolerant microalgae collected from Arctic, subarctic, Antarctic, and subalpine habitats. Strains characterized in this effort include: Chlorella antarctica UTEX1959, Chlorella sp. UTEXSNO69, Chloromonas rosae UTEXSNO11, Phaeodactylum tricornutum UTEX646, and Stichococcus minutus CCALA727. Observed productivities of the characterized strains ranged from 1.74 ± 0.25 to 8.18 ± 0.81 g m –2 day –1 (as ash-free dry weight). For each strain, a temperature tolerance profile was generated to identify the most appropriate season (s) for cultivation. The two most promising strains, Chlorella sp. UTEX SNO69 and P. tricornutum UTEX646, were tested alongside the DISCOVR winter benchmark strain Monoraphidium minutum 26B-AM in outdoor open ponds at the PNNL Algae Testbed (PAT) in Arizona. Further, under cold-season outdoor pond conditions, Chlorella sp. UTEXSNO69 achieved average areal biomass productivities of 8.21 ± 0.50 g m –2 day –1 , not significantly different from that of the benchmark strain (8.52 ± 0.43 g m –2 day –1 , p > 0.05). Under spring outdoor pond conditions, P. tricornutum UTEX646 achieved average areal biomass productivities 10.34 ± 0.27 g m –2 day –1 , not significantly different from that of the benchmark (10.07 ± 0.50 g m –2 day –1 ) under the tested conditions (p > 0.05). The streamlined pipeline was thus demonstrated to successfully characterize productive microalgae strains for outdoor deployment by weeding out algae strains that were not productive under the tested dynamic light and temperature conditions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Life cycle energy and environmental impacts of hydroprocessed renewable jet fuel production from pennycress

There is a growing interest in making the overall aviation industry more environmentally-friendly by developing advanced biofuels. In this context, the main driver is establishing feedstocks with lower environmental loads and higher energy use efficiency. The objective of this study was to evaluate the energy requirement and environmental impacts of hydroprocessed renewable jet fuel (HRJ) production from pennycress. The system boundary included pennycress production, logistics, oil extraction and conversion to HRJ, wastewater treatment, and electricity and steam generation. Energy allocation method was used for the analysis. The functional unit was considered to be one GJ of HRJ, and the biorefinery size was considered to be 18.9 million l/yr (5 million gal/yr) HRJ. Energy use efficiency of pennycress-based HRJ production was estimated to be 3.9–5.5 (90% central range), which was higher than that of HRJ from other oilseeds, such as canola. Global warming potential of pennycress-based HRJ (35–49 kgCO 2 eq/GJ of HRJ (90% central range)) was also lower than those of HRJ from similar oilseeds and the commercial jet fuel baseline. Pennycress production was the main contributor to the total energy use and environmental impacts of HRJ production, mainly due to the use of nitrogen fertilizer for production, and fuel combustion for farm operations. Pennycress yield was identified as the most sensitive parameter affecting the energy use efficiency and environmental impacts of HRJ production. Furthermore, the outcomes of this study are useful for identifying the performance targets towards improving energy use efficiency and environmental performance of pennycress-based HRJ production at the commercial scale.

09 BIOMASS FUELS↗
DOE OSTI2015

Anti-fibrotic effects of a novel small compound on the regulation of cytokine production in a mouse model of colorectal fibrosis

Intestinal fibrotic stricture is a major complication of inflammatory bowel disease. Despite its clinical importance, anti-fibrotic therapy has not been implemented. Transforming growth factor-β (TGF-β) is considered to be a major factor contributing to tissue fibrosis. We have previously shown that the administration of a small compound, HSc025, which promotes the nuclear translocation of YB-1 as a downstream effector of IFN-γ and antagonizes TGF-β/Smad signaling, improves fibrosis in several murine tissues. In this study, we evaluated the anti-fibrotic effect of HSc025 on colorectal fibrosis in TNBS-induced murine chronic colitis. Daily oral administration of HSc025 (3, 15 and 75 mg/kg) suppressed collagen production and decreased the severity of colorectal fibrosis in a dose-dependent manner. In addition, the local production of TGF-β was decreased after HSc025 treatment, whereas that of IL-13 and TNF-α was not affected. HSc025 administration maintained the level of IFN-γ production, even at a late stage when IFN-γ production was lost without the drug treatment. These results demonstrate that HSc025 could be a therapeutic candidate for intestinal fibrosis in inflammatory bowel disease that acts by altering the local production of cytokines, as well as by directly suppressing collagen production. - Highlights: • Colorectal fibrosis of TNBS-induced colitis was attenuated by HSc025 administration. • Local production of TGF-b was suppressed by the modulation of TGF-b/IFN-g signaling. • Derepression of IFN-g production was induced by the drug treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Mitigation of ASR by the use of LiNO{sub 3}—Characterization of the reaction products

The influence of the LiNO{sub 3} on the ASR product was studied both in a model system and in mortars. In the model system, the addition of LiNO{sub 3} decreases the dissolution rate and the solubility of silica. Lithium changes the 2-dimensional cross-linked (Q{sub 3} dominated) network of the ASR product into a less structured, Q{sub 2} dominated product, likely by adopting the role of calcium. In the mortar samples the addition of LiNO{sub 3} decreases expansion and significantly influences the chemical composition and the morphology of the reaction product. Lithium decreases the calcium, sodium and potassium content and changes the relatively porous plate-like reaction product into a dense one without texture. The findings in the mortars indicate that the ASR-suppressing effect of lithium is caused by the lower potential of the reaction product to swell. Furthermore, it forms a protective barrier after an initial reaction slowing down ASR. - Highlights: • Detection of lithium in ASR product by ToF-SIMS • Relation between composition of pore solution and ASR product • Identification of ASR suppressing mechanisms of LiNO{sub 3}.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Accounting for forest carbon pool dynamics in product carbon footprints: Challenges and opportunities

Modification and loss of forests due to natural and anthropogenic disturbance contribute an estimated 20% of annual greenhouse gas (GHG) emissions worldwide. Although forest carbon pool modeling rarely suggests a 'carbon neutral' flux profile, the life cycle assessment community and associated product carbon footprint protocols have struggled to account for the GHG emissions associated with forestry, specifically, and land use generally. Principally, this is due to underdeveloped linkages between life cycle inventory (LCI) modeling for wood and forest carbon modeling for a full range of forest types and harvest practices, as well as a lack of transparency in globalized forest supply chains. In this paper, through a comparative study of U.S. and Chinese coated freesheet paper, we develop the initial foundations for a methodology that rescales IPCC methods from the national to the product level, with reference to the approaches in three international product carbon footprint protocols. Due to differences in geographic origin of the wood fiber, the results for two scenarios are highly divergent. This suggests that both wood LCI models and the protocols need further development to capture the range of spatial and temporal dimensions for supply chains (and the associated land use change and modification) for specific product systems. The paper concludes by outlining opportunities to measure and reduce uncertainty in accounting for net emissions of biogenic carbon from forestland, where timber is harvested for consumer products. - Highlights: Black-Right-Pointing-Pointer Typical life cycle assessment practice for consumer products often excludes significant land use change emissions when estimating carbon footprints. Black-Right-Pointing-Pointer The article provides a methodology to rescale IPCC guidelines for product-level carbon footprints. Black-Right-Pointing-Pointer Life cycle inventories and product carbon footprint protocols need more comprehensive land use-related accounting. Black-Right-Pointing-Pointer Interdisciplinary collaboration linking the LCA and forest carbon modeling communities is necessary.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Measurements of 14 C in ancient ice from Taylor Glacier, Antarctica constrain in situ cosmogenic 14 CH 4 and 14 CO production rates

Carbon-14 ( 14 C) is incorporated into glacial ice by trapping of atmospheric gases as well as direct near-surface in situ cosmogenic production. 14 C of trapped methane ( 14 CH 4 ) is a powerful tracer for past CH 4 emissions from “old” carbon sources such as permafrost and marine CH 4 clathrates. 14 C in trapped carbon dioxide ( 14 CO 2 ) can be used for absolute dating of ice cores. In situ produced cosmogenic 14 C in carbon monoxide ( 14 CO) can potentially be used to reconstruct the past cosmic ray flux and past solar activity. Unfortunately, the trapped atmospheric and in situ cosmogenic components of 14 C in glacial ice are difficult to disentangle and a thorough understanding of the in situ cosmogenic component is needed in order to extract useful information from ice core 14 C. Here, we analyzed very large (≈1000 kg) ice samples in the 2.26–19.53 m depth range from the ablation zone of Taylor Glacier, Antarctica, to study in situ cosmogenic production of 14 CH 4 and 14 CO. All sampled ice is >50 ka in age, allowing for the assumption that most of the measured 14 C originates from recent in situ cosmogenic production as ancient ice is brought to the surface via ablation. Our results place the first constraints on cosmogenic 14 CH 4 production rates and improve on prior estimates of 14 CO production rates in ice. We find a constant 14 CH 4 / 14 CO production ratio (0.0076 ± 0.0003) for samples deeper than 3 m, which allows the use of 14 CO for correcting the 14 CH 4 signals for the in situ cosmogenic component. Our results also provide the first unambiguous confirmation of 14 C production by fast muons in a natural setting (ice or rock) and suggest that the 14 C production rates in ice commonly used in the literature may be too high.

58 GEOSCIENCES↗
DOE OSTI2020

Numerical study of the effect of propped surface area and fracture conductivity on shale gas production: Application for multi-size proppant pumping schedule design

Hydraulic fracturing is a technique extensively used in the oil and gas industry, where water, proppant (sand) and additives are injected into unconventional reservoirs to enhance the recovery of shale hydrocarbon. Although some previous studies have developed pumping schedules that maximize gas production for a single-size proppant, there are very few studies that consider the effect of varying proppant diameters across pumping stages on shale gas production. Motivated by this, we carried out an extensive sensitivity analysis to determine the effect of different proppant diameters on the average fracture conductivity (FC), average propped surface area (PSA) and cumulative shale gas production volume. We found out that the cumulative shale gas production volume depends on both the average PSA and average FC. We also found out that small-diameter proppant resulted in higher average PSA and lower average FC, whereas large-diameter proppant resulted in lower average PSA and higher average FC. Hence, we designed a multi-size proppant pumping schedule considering both of these parameters into account for simultaneously propagating multiple fractures to maximize shale gas production from unconventional reservoirs. Since the size of injected proppant particles determines the average PSA and average FC for the propped hydraulic fractures, we developed a novel framework called Sequentially Interlinked Modeling Structure (SIMS) to predict the average PSA, average FC and cumulative shale gas production volume at the end of 10 years for a given pumping schedule. Then, we used this SIMS framework to obtain a multi-size proppant pumping schedule that maximizes shale gas production. In closing, we demonstrated that the obtained pumping schedule gives a cumulative shale gas production volume greater than the values obtained from the existing pumping schedules.

03 NATURAL GAS↗
DOE OSTI2024

Measurement of 𝐽∕𝜓and 𝜓(2𝑆)production in 𝑝 +𝑝and 𝑝 +𝑑interactions at 120 GeV

We report the p + p and p + d differential cross sections measured in the SeaQuest experiment for J/psi and psi(2S) production at 120GeV beam energy covering the forward x-Feynman (x(F)) range of 0.5 < x(F) < 0.9. The measured cross sections are in good agreement with theoretical calculations based on the nonrelativistic QCD (NRQCD) using the long-distance matrix elements deduced from a recent global analysis of proton- and pion-induced charmonium production data. The sigma(psi(2S))/sigma(J/psi) cross section ratios are found to increase as x(F) increases, indicating that the q (q) over bar. annihilation process has larger contributions in the psi(2S) production than the J/psi production. The sigma(pd)/2 sigma(pp) cross section ratios are observed to be significantly different for the DrellYan process and J/psi production, reflecting their different production mechanisms. We find that the sigma(pd)/2 sigma(pp) ratios for J/psi production at the forward x(F) region are sensitive to the (d) over bar/(u) over bar flavor asymmetry of the proton sea, analogous to the Drell-Yan process. The transverse momentum (p(T)) distributions for J/psi and psi(2S) production are also presented and compared with data collected at higher center-of-mass energies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Evaluating Multimodel Ensemble Seasonal Climate Forecasts on Rangeland Plant Production in the California Annual Grassland

Seasonal precipitation and temperature directly affect total plant production in the California Annual Grassland (CAG). Technological advances have resulted in skillful seasonal climate forecasts (i.e., significant correlations between actual and forecasted climate), which could be input into plant production models to inform stocking and other rangeland management decisions. This study presents a procedure for forecasting plant production in the CAG ecosystem to predict annual plant production for grazing, restoration, or other rangeland management practices using a combination of historical gridMET climate data and seasonal hindcasts (i.e., retrospective forecasts, from the North American Multi-Model Ensemble program). Further, the results of this study first confirmed high forecast skill, throughout the growing season at all sites. We also identified skillful plant production forecasts across most of the growing season at two sites and in three of the seven forecasting months at one study site. Forecasting climate and end-of-year plant production across the growing season at three CAG sites allowed us to identify the places and times in the growing season when forecasting might be most helpful in informing management decisions. Integrating plant production forecasting into rangeland management practices could significantly improve rangeland management outcomes. These procedures provide a user guide for creating plant production forecasts for any given area of interest and may be applicable across a wide range of other agricultural and rangeland management systems.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Managing weather- and market price-related financial risks in algal biofuel production

Large-scale algae production has garnered interest due to its potential as a biofuel feedstock. Previous research assessing the profitability of algae products has been mostly based on values averaged over time, but algae production and resulting financial returns exhibit significant variability due to weather and fluctuations in selling prices for algae-based products. In other sectors, producers often reduce weather- and market price-related financial risk with financial instruments such as insurance, but little research has been performed on the design of insurance products to protect algae producers. Furthermore, this study develops a novel index-based insurance instrument that pays-out during unfavorable weather and market conditions, then explores the instrument's effectiveness, combined with a cash reserve, in reducing revenue stream variability for an algae producer. Results indicate that a biophysically based index-insurance product tailored to the specific financial risks in algae production can reduce variability in net revenues and can do so at a lower cost than relying solely on cash reserves, the most common financial risk management tool. Assessing the performance of index-insurance in algae production is particularly timely given the passage of the 2018 Farm Bill, which newly opens opportunities for the USDA to provide crop insurance to algae producers.

09 BIOMASS FUELS↗
DOE OSTI2022

Decoupling of greenness and gross primary productivity as aridity decreases

Ecosystem primary productivity is a key ecological process influencing many ecosystem services, including carbon storage. Thus, clarifying how primary productivity in terrestrial ecosystems responds to climatic variability can reveal key mechanisms that will drive future changes in the global carbon budget. Satellite products of canopy greenness are widely used as proxies for vegetation productivity to evaluate how ecosystems respond to climate variability. However, to what degree inter-annual variations in productivity are consistent with greenness and how this relationship varies spatially remains unclear. Here we investigated the strength of the coupling between inter-annual variations in leaf area index (LAI, a measure of greenness) and ecosystem gross primary productivity (GPP) derived from eddy covariance towers, i.e., the r2 of the LAI-GPP relationship. Overall, inter-annual GPP and LAI were highly coupled (i.e., high r2) in arid grasslands, but were fully decoupled in mesic evergreen broadleaf forests, indicating that this relationship varies strongly along aridity gradients. A possible mechanism of the spatial variation in the LAI-GPP relationship is that the tradeoff between ecosystem structure (LAI) and physiology (photosynthesis per unit leaf area) becomes stronger in more humid climates. Land models overestimated the r2 of LAI-GPP correlation for most ecosystem types and failed to capture the spatial pattern along aridity gradients. We conclude that relying on greenness products for evaluating inter-annual changes in vegetation productivity may bias assessments, especially in tropical rainforest ecosystems. Our findings may also reconcile observed disparities between responses in greenness and GPP during drought in Amazon forests.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Methods to estimate the transfer of contaminants into recycling products – A case study from Austria

Highlights: • Recycling of waste materials includes the risk of recycling hazardous substances. • Comparison of contaminants in recycling products to primary products and check of compliance with limit values. • Evaluation matrix to quickly scan the environmental and health risks of wastes for recycling. • Optimised sorting and quality control systems prevent transfer of contaminants into product cycles. - Abstract: Recycling of waste materials is desirable to reduce the consumption of limited primary resources, but also includes the risk of recycling unwanted, hazardous substances. In Austria, the legal framework demands secondary products must not present a higher risk than comparable products derived from primary resources. However, the act provides no definition on how to assess this risk potential. This paper describes the development of different quantitative and qualitative methods to estimate the transfer of contaminants in recycling processes. The quantitative methods comprise the comparison of concentrations of harmful substances in recycling products to corresponding primary products and to existing limit values. The developed evaluation matrix, which considers further aspects, allows for the assessment of the qualitative risk potential. The results show that, depending on the assessed waste fraction, particular contaminants can be critical. Their concentrations were higher than in comparable primary materials and did not comply with existing limit values. On the other hand, the results show that a long-term, well-established quality control system can assure compliance with the limit values. The results of the qualitative assessment obtained with the evaluation matrix support the results of the quantitative assessment. Therefore, the evaluation matrix can be suitable to quickly screen waste streams used for recycling to estimate their potential environmental and health risks. To prevent the transfer of contaminants into product cycles, improved data of relevant substances in secondary resources are necessary. In addition, regulations for material recycling are required to assure adequate quality control measures, including limit values.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

IL-1β directly inhibits milk lipid production in lactating mammary epithelial cells concurrently with enlargement of cytoplasmic lipid droplets

Highlights: • IL-1β inhibits milk lipid production concurrently with enlargement of lipid droplets. • IL-1β, IL-6, and TNF-α affect milk lipid production in different manners. • IL-1β rapidly induced activation of STAT3 concurrently with inactivation of STAT5. • IL-1β activates the mRNA expression of IL-6 and TNF-α in mammary epithelial cells. Mammary epithelial cells (MECs) in lactating mammary glands produce milk lipid, which provides a large percentage of calories and bioactive lipids for appropriate infant growth. However, secreted milk lipid is often reduced concurrently with increases in IL-1β, IL-6, and TNF-α in mammary glands with mastitis. In this study, we investigated whether those cytokines directly influenced lipid production and secretion. A lactating MEC culture model with high lipid production ability was prepared by culture with oleic acid. TNF-α, IL-1β, and IL-6 differentially affected lipid production and secretion in lactating MECs. In particular, IL-1β treatment significantly reduced amounts of secreted triglycerides by 97% compared with the control concurrently with enlargement of cytoplasmic lipid droplets in MECs. IL-1β also decreased mRNA expression of Fabp3 and Srebp1 and the amount of aquaporin 3, GLUT-1 and adipophilin in the milk lipid production pathway. Furthermore, IL-1β inactivated STAT5 and glucocorticoid signaling to induce milk production in MECs, whereas STAT3 and NFκB signaling was activated. IL-1β induced mRNA expression of IL-6 and TNF-α in MECs. Therefore, we suggest that IL-1β is a key inhibitor of lipid production and secretion in lactating MECs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Fluctuating pH for efficient photomixotrophic succinate production

Cyanobacteria are attracting increasing attention as a photosynthetic chassis organism for diverse biochemical production, however, photoautotrophic production remains inefficient. Photomixotrophy, a method where sugar is used to supplement baseline autotrophic metabolism in photosynthetic hosts, is becoming increasingly popular for enhancing sustainable bioproduction with multiple input energy streams. In this study, the commercially relevant diacid, succinate, was produced photomixotrophically. Succinate is an important industrial chemical that can be used for the production of a wide array of products, from pharmaceuticals to biopolymers. In this system, the substrate, glucose, is transported by a proton symporter and the product, succinate, is hypothesized to be transported by another proton symporter, but in the opposite direction. Thus, low pH is required for the import of glucose and high pH is required for the export of succinate. Succinate production was initiated in a pH 7 medium containing bicarbonate. Glucose was efficiently imported at around neutral pH. Utilization of bicarbonate by CO 2 fixation raised the pH of the medium. As succinate, a diacid, was produced, the pH of the medium dropped. By repeating this cycle with additional pH adjustment, those contradictory requirements for transport were overcome. pH affects a variety of biological factors and by cycling from high pH to neutral pH processes such as CO 2 fixation rates and CO 2 solubility can vary. In this study the engineered strains produced succinate during fluctuating pH conditions, achieving a titer of 5.0gL -1 after 10 days under shake flask conditions. Finally, these results demonstrate the potential for photomixotrophic production as a viable option for the large-scale production of succinate.

36 MATERIALS SCIENCE↗
DOE OSTI2015

UV Photodissociation Dynamics of the CH 3 CHOO Criegee Intermediate: Action Spectroscopy and Velocity Map Imaging of O-Atom Products

We report that UV excitation of jet-cooled CH 3 CHOO on the B 1 A'–X 1 A' transition results in dissociation to two spin-allowed product channels: CH 3 CHO X 1 A' + O 1 D and CH 3 CHO a 3 A" + O 3 P. The O 1 D and O 3 P products are detected using 2 + 1 REMPI at 205 and 226 nm, respectively, for action spectroscopy and velocity map imaging studies. The O 1 D action spectrum closely follows the previously reported UV absorption spectrum for jet-cooled CH 3 CHOO [ Beames et al. J. Chem. Phys. 2013 , 138 , 244307]. Velocity map images of the O 1 D products following excitation of CH 3 CHOO at 305, 320, and 350 nm exhibit anisotropic angular distributions indicative of rapid (ps) dissociation, along with broad and unstructured total kinetic energy (TKER) distributions that reflect the internal energy distribution of the CH 3 CHO X 1 A' coproducts. The O 3 P action spectrum turns on near the peak of the UV absorption spectrum (ca. 324 nm) and extends to higher energy with steadily increasing O 3 P yield. Excitation of CH 3 CHOO at 305 nm, attributed to absorption of the more stable syn -conformer, also results in an anisotropic angular distribution of O 3 P products arising from rapid (ps) dissociation, but a narrower TKER distribution since less energy is available to the CH 3 CHO a 3 A" + O 3 P products. The threshold for the higher energy CH 3 CHO a 3 A" + O 3 P product channel is determined to be ca. 88.4 kcal mol –1 from the termination of the TKER distribution and the onset of the O 3 P action spectrum. This threshold is combined with the singlet-triplet spacings of O atoms and acetaldehyde to establish the dissociation energy for syn -CH 3 HOO X 1 A' to the lowest spin-allowed product channel, CH 3 CHO X 1 A' + O 1 D, of ≤55.9 ± 0.4 kcal mol –1 . Lastly, a harmonic normal-mode analysis is utilized to identify the vibrational modes of CH 3 CHO likely to be excited upon dissociation into the two product channels.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Trade-offs between microbiome diversity and productivity in a stratified microbial mat

Productivity is a major determinant of ecosystem diversity. Microbial ecosystems are the most diverse on the planet yet very few relationships between diversity and productivity have been reported as compared to macro-ecological studies. Here we evaluated the spatial relationships of productivity and microbiome diversity in a laboratory-cultivated photosynthetic mat. The goal was to determine how spatial diversification of microorganisms drives localized carbon and energy acquisition rates. We measured sub-millimeter depth profiles of net primary-productivity and gross oxygenic photosynthesis in the context of the localized microenvironment and community structure and observed negative correlations between species richness and productivity within the energy-replete, photic zone. Variations between localized community structures were associated with distinct taxa as well as environmental profiles describing a continuum of biological niches. Spatial regions corresponding to high primary productivity and photosynthesis rates had relatively low species richness and high evenness. Hence, this system exhibited negative species-productivity and species–energy relationships. These negative relationships may be indicative of photosynthetically-driven, light-controlled mat ecosystems that are able to be the most productive with a relatively smaller, even distributions of species that specialize within the highly-oxic, photic zones.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Isobutanol production freed from biological limits using synthetic biochemistry

Cost competitive conversion of biomass-derived sugars into biofuel will require high yields, high volumetric productivities and high titers. Suitable production parameters are hard to achieve in cell-based systems because of the need to maintain life processes. As a result, next-generation biofuel production in engineered microbes has yet to match the stringent cost targets set by petroleum fuels. Removing the constraints imposed by having to maintain cell viability might facilitate improved production metrics. Here, we report a cell-free system in a bioreactor with continuous product removal that produces isobutanol from glucose at a maximum productivity of 4 g L –1 h –1 , a titer of 275 g L –1 and 95% yield over the course of nearly 5 days. These production metrics exceed even the highly developed ethanol fermentation process. Our results suggest that moving beyond cells has the potential to expand what is possible for bio-based chemical production.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗