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DOE OSTI2014

US Woody Crop Yield Potential Database Documentation with Referenced Yield Summary Tables

A woody crop yield potential (WCYP) database was created containing yield results with as much associated information as was available concerning the sites, soils, and experimental treatments. The database summarizes a very broad set of old and new standing biomass data from plantation-grown hardwoods and softwoods established under a wide range of conditions across the United States and Canada. The WCYP database, together with this document, is being published to disseminate information on what is available in the literature with respect to yield evaluations and to inform people that not all yield data in the open literature are suitable for evaluation of “potential” regional yields. It has also been presented with the hope that much more information will be collected and added to the WCYP database. The current set of data in the WCYP database is derived from 41 unique reference sources describing 79 experiments in the United States or southern Canada with a total of 473 different treatments. The database contains several worksheets. The worksheet that reports the complete yield curves contains roughly 1,660 rows of data and 81 columns of parameters reporting yields and associated treatment factors. Separate worksheets, linked by the source publication author and year, describe the sites and soils associated with each experiment; another separate worksheet assembles only the final yields deemed appropriate for yield potential analysis. There are additional worksheets with conversion factors relevant to the database and notes pertaining to decisions made regarding organization of the data. This technical manuscript describes how the information was assembled to create the WCYP database that is simultaneously being published on the US Department of Energy (DOE) Bioenergy Knowledge Discovery Framework website maintained by Oak Ridge National Laboratory (ORNL). A summary table with links to all worksheets in the database can be found at the web address https://www.bioenergykdf.net/WCYP .

09 BIOMASS FUELS↗

DOE OSTI2021

Huntingtin structure is orchestrated by HAP40 and shows a polyglutamine expansion-specific interaction with exon 1

Huntington’s disease results from expansion of a glutamine-coding CAG tract in the huntingtin (HTT) gene, producing an aberrantly functioning form of HTT. Both wildtype and disease-state HTT form a hetero-dimer with HAP40 of unknown functional relevance. Here, we demonstrate in vivo and in cell models that HTT and HAP40 cellular abundance are coupled. Integrating data from a 2.6 Å cryo-electron microscopy structure, cross-linking mass spectrometry, small-angle X-ray scattering, and modeling, we provide a near-atomic-level view of HTT, its molecular interaction surfaces and compacted domain architecture, orchestrated by HAP40. Native mass spectrometry reveals a remarkably stable hetero-dimer, potentially explaining the cellular inter-dependence of HTT and HAP40. The exon 1 region of HTT is dynamic but shows greater conformational variety in the polyglutamine expanded mutant than wildtype exon 1. Our data provide a foundation for future functional and drug discovery studies targeting Huntington’s disease and illuminate the structural consequences of HTT polyglutamine expansion.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2014

Pilot Implementation of a Field Study Design to Evaluate the Impact of Source Control Measures on Indoor Air Quality in High Performance Homes

To improve the indoor air quality in new, high performance homes, a variety of standards and rating programs have been introduced to identify building materials that are designed to have lower emission rates of key contaminants of concern and a number of building materials are being introduced that are certified to these standards. For example, the U.S. Department of Energy (DOE) Zero Energy Ready Home program requires certification under the U.S. Environmental Protection Agency (EPA) Indoor airPLUS (IaP) label, which requires the use of PS1 or PS2 certified plywood and OSB; low-formaldehyde emitting wood products; low- or no-VOC paints and coatings as certified by Green Seal Standard GS-11, GreenGuard, SCS Indoor Advantage Gold Standard, MPI Green Performance Standard, or another third party rating program; and Green Label-certified carpet and carpet cushions. However, little is known regarding the efficacy of the IAP requirements in measurably reducing contaminant exposures in homes. The goal of this project is to develop a robust experimental approach and collect preliminary data to support the evaluation of indoor air quality (IAQ) measures linked to IAP-approved low-emitting materials and finishes in new residential homes. To this end, the research team of Pacific Northwest National Laboratory (PNNL) and Lawrence Berkeley National Laboratory (LBNL) developed a detailed experimental plan to measure IAQ constituents and other parameters, over time, in new homes constructed with materials compliant with IAP’s low-emitting material and ventilation requirements (i.e., section 6.1, 6.2, 6.3, and 7.2) and similar homes constructed to the state building code with conventional materials. The IAQ in IAP and conventional homes of similar age, location, and construction style is quantified as the differences in the speciated VOC and aldehyde concentrations, normalized to dilution rates. The experimental plan consists of methods to evaluate the difference between low-emitting and “conventional” materials as installed in newly constructed residential homes using both (1) highly controlled, short-term active samples to precisely characterize the building-related chemical emissions and building contents and (2) a week-long passive sample designed to capture the impact of occupant behavior and related activities on measured IAQ contaminant levels indoors. The combination of detailed short-term measurements with the home under controlled/consistent conditions during pre- and post-occupancy and the week-long passive sampling data provide the opportunity to begin to separate the different emission sources and help isolate and quantify variability in the monitored homes. Between April and August 2014, the research team performed pre-occupancy and post-occupancy sampling in one conventional home and two homes built with low-emitting materials that were generally consistent with EPA’s Indoor airPLUS guidelines. However, for a number of reasons, the full experimental plan was not implemented. The project was intended to continue for up to three years to asses long-term changes in IAQ but the project was limited to one calendar year. As a result, several of the primary research questions related to seasonal impacts and the long-term trends in IAQ could not be addressed. In addition, there were several unexpected issues related to recruiting, availability of home types, and difficulty coordinating with builders/realtors/homeowners. Several field monitoring issues also came up that provide “lessons learned” that led to improvements to the original monitoring plan. The project produced a good experimental plan that is expected to be be useful for future efforts collecting data to support answering these same or similar research questions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2023

Datasets for DOE 2023 Communities LEAP

This data is aligned to eligibility criteria outlined in the United States Department of Energy (DOE) 2023 Communities LEAP (Local Energy Action Program). Please visit the LEAP website (https://www.energy.gov/communitiesLEAP/communities-leap) to learn more about LEAP and gain additional contextual information for how these data may be used. The data provided approximates how the eligibility criteria apply at the census tract level across the United States. This EDX submission provides access to information pertaining to each of the four eligibility criteria outlined (average energy burden, percent low income, communities with a historic economic dependence on fossil fuel industrial facilities, and disadvantaged communities) for all census tracts within the 50 U.S. States, the District of Columbia (D.C.), and Puerto Rico. This information can be access in a detailed excel spreadsheet or through the linked interactive web application (https://arcgis.netl.doe.gov/portal/apps/experiencebuilder/experience/?id=2a77f443d72b4a4d82474b3ffe33b8cd). Please note that while these data are provided at the census tract level, census tracts do not necessarily have the same physical boundaries as a community but were used as they provide the closest proxy based on publicly available information collected using an empirically robust method. U.S. territories are not listed but are eligible to apply to Communities LEAP. As stated in the Opportunity Announcement, applying communities should describe how they meet the eligibility criteria in their application even if these data do not specifically show that they are eligible.

2023↗

DOE OSTI2021

Conformational dynamics linked to domain closure and substrate binding explain the ERAP1 allosteric regulation mechanism

The endoplasmic-reticulum aminopeptidase ERAP1 processes antigenic peptides for loading on MHC-I proteins and recognition by CD8 T cells as they survey the body for infection and malignancy. Crystal structures have revealed ERAP1 in either open or closed conformations, but whether these occur in solution and are involved in catalysis is not clear. Here, we assess ERAP1 conformational states in solution in the presence of substrates, allosteric activators, and inhibitors by small-angle X-ray scattering. We also characterize changes in protein conformation by X-ray crystallography, and we localize alternate C-terminal binding sites by chemical crosslinking. Structural and enzymatic data suggest that the structural reconfigurations of ERAP1 active site are physically linked to domain closure and are promoted by binding of long peptide substrates. These results clarify steps required for ERAP1 catalysis, demonstrate the importance of conformational dynamics within the catalytic cycle, and provide a mechanism for the observed allosteric regulation and Lys/Arg528 polymorphism disease association.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2019

ManiNetCluster: a novel manifold learning approach to reveal the functional links between gene networks

BACKGROUND:The coordination of genomic functions is a critical and complex process across biological systems such as phenotypes or states (e.g., time, disease, organism, environmental perturbation). Understanding how the complexity of genomic function relates to these states remains a challenge. To address this, we have developed a novel computational method, ManiNetCluster, which simultaneously aligns and clusters gene networks (e.g., co-expression) to systematically reveal the links of genomic function between different conditions. Specifically, ManiNetCluster employs manifold learning to uncover and match local and non-linear structures among networks, and identifies cross-network functional links. RESULTS:We demonstrated that ManiNetCluster better aligns the orthologous genes from their developmental expression profiles across model organisms than state-of-the-art methods (p-value <2.2×10-16). This indicates the potential non-linear interactions of evolutionarily conserved genes across species in development. Furthermore, we applied ManiNetCluster to time series transcriptome data measured in the green alga Chlamydomonas reinhardtii to discover the genomic functions linking various metabolic processes between the light and dark periods of a diurnally cycling culture. We identified a number of genes putatively regulating processes across each lighting regime. CONCLUSIONS:ManiNetCluster provides a novel computational tool to uncover the genes linking various functions from different networks, providing new insight on how gene functions coordinate across different conditions. ManiNetCluster is publicly available as an R package at https://github.com/daifengwanglab/ManiNetCluster.

Comparative network analysis↗

DOE OSTI2017

C{sub 60}{sup +} and the Diffuse Interstellar Bands: An Independent Laboratory Check

In 2015, Campbell et al. presented spectroscopic laboratory gas phase data for the fullerene cation, C{sub 60}{sup +}, that coincide with the reported astronomical spectra of two diffuse interstellar band (DIB) features at 9633 and 9578 Å. In the following year, additional laboratory spectra were linked to three other and weaker DIBs at 9428, 9366, and 9349 Å. The laboratory data were obtained using wavelength-dependent photodissociation spectroscopy of small (up to three) He-tagged C{sub 60}{sup +}--He{sub n} ion complexes, yielding rest wavelengths for the bare C{sub 60}{sup +} cation by correcting for the He-induced wavelength shifts. Here we present an alternative approach to derive the rest wavelengths of the four most prominent C{sub 60}{sup +} absorption features, using high-resolution laser dissociation spectroscopy of C{sub 60}{sup +} embedded in ultracold He droplets. Accurate wavelengths of the bare fullerene cation are derived from linear wavelength shifts recorded for He{sub n} C{sub 60}{sup +} species with n up to 32. A careful analysis of all of the available data results in precise rest wavelengths (in air) for the four most prominent C{sub 60}{sup +} bands: 9631.9(1) Å, 9576.7(1) Å, 9427.5(1) Å, and 9364.9(1) Å. The corresponding bandwidths have been derived and the relative band intensity ratios are discussed.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

Design of composite inhibitors targeting glutamate carboxypeptidase II: the importance of effector functionalities

Inhibitors targeting human glutamate carboxypeptidase II (GCPII) typically consist of a P1' glutamate-derived binding module, which warrants the high affinity and specificity, linked to an effector function that is positioned within the entrance funnel of the enzyme. In this paper we present a comprehensive structural and computational study aimed at dissecting the importance of the effector function for GCPII binding and affinity. To this end we determined crystal structures of human GCPII in complex with a series of phosphoramidate-based inhibitors harboring effector functions of diverse physicochemical characteristics. Our data show that higher binding affinities of phosphoramidates, compared to matching phosphonates, are linked to the presence of additional hydrogen bonds between Glu424 and Gly518 of the enzyme and the amide group of the phosphoramidate. While the positioning of the P1' glutamate-derived module within the S1' pocket of GCPII is invariant, interaction interfaces between effector functions and residues lining the entrance funnel are highly varied, with the positively charged arginine patch defined by Arg463, Arg534 and Arg536 being the only ‘hot-spot’ common to several studied complexes. This variability stems in part from the fact that the effector/GCPII interfaces generally encompass isolated areas of nonpolar residues within the entrance funnel and resulting van der Waals contacts lack the directionality typical for hydrogen bonding interactions. The presented data unravel a complexity of binding modes of inhibitors within non-prime site(s) of GCPII and can be exploited for the design of novel GCPII-specific compounds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2013

In situ dehydration behavior of zeolite-like pentagonite: A single-crystal X-ray study

The structural modifications upon heating of pentagonite, Ca(VO)(Si{sub 4}O{sub 10}){center_dot}4H{sub 2}O (space group Ccm2{sub 1}, a=10.3708(2), b=14.0643(2), c=8.97810(10) A, V=1309.53(3) A{sup 3}) were investigated by in situ temperature dependent single-crystal X-ray structure refinements. Diffraction data of a sample from Poona district (India) have been measured in steps of 25 up to 250 Degree-Sign C and in steps of 50 Degree-Sign C between 250 and 400 Degree-Sign C. Pentagonite has a porous framework structure made up by layers of silicate tetrahedra connected by V{sup 4+}O{sub 5} square pyramids. Ca and H{sub 2}O molecules are extraframework occupants. Room temperature diffraction data allowed refinement of H positions. The hydrogen-bond system links the extraframework occupants to the silicate layers and also interconnects the H{sub 2}O molecules located inside the channels. Ca is seven-fold coordinated forming four bonds to O of the tetrahedral framework and three bonds to extraframework H{sub 2}O. The H{sub 2}O molecule at O9 showing a high displacement parameter is not bonded to Ca. The dehydration in pentagonite proceeds in three steps. At 100 Degree-Sign C the H{sub 2}O molecule at O8 was released while O9 moved towards Ca. As a consequence the displacement parameter of H{sub 2}O at O9 halved compared to that at room temperature. The unit-cell volume decreased to 1287.33(3) A{sup 3} leading to a formula with 3H{sub 2}O per formula unit (pfu). Ca remained seven-fold coordinated. At 175 Degree-Sign C Ca(VO)(Si{sub 4}O{sub 10}){center_dot}3H{sub 2}O transformed into a new phase with 1H{sub 2}O molecule pfu characterized by doubling of the c axis and the monoclinic space group Pn. Severe bending of specific T--O--T angles led to contraction of the porous three-dimensional framework. In addition, H{sub 2}O at O9 was expelled while H{sub 2}O at O7 approached a position in the center of the channel. The normalized volume decreased to 1069.44(9) A{sup 3}. The Ca coordination reduced from seven- to six-fold. At 225 Degree-Sign C a new anhydrous phase with space group Pna2{sub 1} but without doubling of c had formed. Release of H{sub 2}O at O7 caused additional contraction of T--O--T angles and volume reduction (V=1036.31(9) A{sup 3}). Ca adopted five-fold coordination. During heating excursion up to 400 Degree-Sign C this anhydrous phase remained preserved. Between room temperature and 225 Degree-Sign C the unit-cell volume decreased by 21% due to dehydration. The dehydration steps compare well with the thermo-gravimetric data reported in the literature. - Graphical abstract: Pentagonite structure at room temperature and at 225 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer We investigate the relationship between the removal of H{sub 2}O molecules and structural modifications of the framework of pentagonite. Black-Right-Pointing-Pointer Pentagonite undergoes phase transitions upon heating. Black-Right-Pointing-Pointer We analyze similarities and differences between pentagonite and related structures.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Is There a Negative Thermal Expansion in Supported Metal Nanoparticles? An in Situ X-ray Absorption Study Coupled with Neural Network Analysis

Interactions with their support, adsorbates, and unique structural motifs are responsible for many intriguing properties and potential applications of supported metal nanoparticles (NPs). At the same time, they complicate the interpretation of experimental data. In fact, the methods and approaches that work well for the ex situ analysis of bulk materials may be inaccurate or introduce artifacts in the in situ analysis of nanomaterials. Here, we revisit the controversial topic of negative thermal expansion and anomalies in the Debye temperature reported for oxide-supported metal NPs. In situ X-ray absorption experimental data collected for Pt NPs in ultrahigh vacuum and an advanced data analysis approach based on an artificial neural network demonstrate that Pt NPs do not exhibit intrinsic negative thermal expansion. Similarly, as for bulk materials, in the absence of adsorbates and strong particle-support interaction, the bond lengths in metal NPs increase with temperature. Lastly, the previously reported anomalies in particle-size-dependent Debye temperatures can also be linked to the artifacts in the interpretation of conventional X-ray absorption data of disordered materials such as NPs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Visualizing Solution Structure at Solid-Liquid Interfaces using Three-Dimensional Fast Force Mapping

Amongst the challenges for a variety of research fields are the visualization of solid-liquid interfaces and understanding how they are affected by the solution conditions such as ion concentrations, pH, ligands, and trace additives, as well as the underlying crystallography and chemistry. Here, in this context, three-dimensional fast force mapping (3D FFM) has emerged as a promising tool for investigating solution structure at interfaces. This capability is based on atomic force microscopy (AFM) and allows the direct visualization of interfacial regions in three spatial dimensions with sub-nanometer resolution. Here we provide a detailed description of the experimental protocol for acquiring 3D FFM data. The main considerations for optimizing the operating parameters depending on the sample and application are discussed. Moreover, the basic methods for data processing and analysis are discussed, including the transformation of the measured instrument observables into tip-sample force maps that can be linked to the local solution structure. Finally, we shed light on some of the outstanding questions related to 3D FFM data interpretation and how this technique can become a central tool in the repertoire of surface science.

Nakouzi, Elias↗

DOE OSTI2016

Constructing Networks of Organelle Functional Modules in Arabidopsis

With the rapid accumulation of gene expression data, gene functional module identification has become a widely used approach in functional analysis. However, tools to identify organelle functional modules and analyze their relationships are still missing. We present a soft thresholding approach to construct networks of functional modules using gene expression datasets, in which nodes are strongly co-expressed genes that encode proteins residing in the same subcellular localization, and links represent strong inter-module connections. Our algorithm has three steps. First, we identify functional modules by analyzing gene expression data. Next, we use a self-adaptive approach to construct a mixed network of functional modules and genes. Finally, we link functional modules that are tightly connected in the mixed network. Analysis of experimental data from Arabidopsis demonstrates that our approach is effective in improving the interpretability of high-throughput transcriptomic data and inferring function of unknown genes.

Arabidopsis thaliana↗

DOE OSTI2019

Probing the Cys-Tyr Cofactor Biogenesis in Cysteine Dioxygenase by the Genetic Incorporation of Fluorotyrosine

Cysteine dioxygenase (CDO) is a nonheme iron enzyme that adds two oxygen atoms from dioxygen to the sulfur atom of L -cysteine. Adjacent to the iron site of mammalian CDO, there is a post-translationally generated Cys-Tyr cofactor, whose presence substantially enhances the oxygenase activity. The formation of the Cys-Tyr cofactor in CDO is an autocatalytic process, and it is challenging to study by traditional techniques because the cross-linking reaction is a side, uncoupled, single-turnover oxidation buried among multiple turnovers of L -cysteine oxygenation. Here, we take advantage of our recent success in obtaining a purely uncross-linked human CDO due to site-specific incorporation of 3,5-difluoro- L -tyrosine (F 2 -Tyr) at the cross-linking site through the genetic code expansion strategy. Using EPR spectroscopy, we show that nitric oxide ( • NO), an oxygen surrogate, similarly binds to uncross-linked F 2 -Tyr157 CDO as in wild-type human CDO. Additionally, we determined X-ray crystal structures of uncross-linked F 2 -Tyr157 CDO and mature wild-type CDO in complex with both L -cysteine and • NO. These structural data reveal that the active site cysteine (Cys93 in the human enzyme), rather than the generally expected tyrosine (i.e., Tyr157), is well-aligned to be oxidized should the normal oxidation reaction uncouple. This structure-based understanding is further supported by a computational study with models built on the uncross-linked ternary complex structure. Together, these results strongly suggest that the first target to oxidize during the iron-assisted Cys-Tyr cofactor biogenesis is Cys93. Based on these data, a plausible reaction mechanism implementing a cysteine radical involved in the cross-link formation is proposed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

ftmsRanalysis: An R package for exploratory data analysis and interactive visualization of FT-MS data

The high-resolution and mass accuracy of Fourier transform mass spectrometry (FT-MS) has made it an increasingly popular technique for discerning the composition of soil, plant and aquatic samples containing complex mixtures of proteins, carbohydrates, lipids, lignins, hydrocarbons, phytochemicals and other compounds. Thus, there is a growing demand for informatics tools to analyze FT-MS data that will aid investigators seeking to understand the availability of carbon compounds to biotic and abiotic oxidation and to compare fundamental chemical properties of complex samples across groups. We present ftmsRanalysis, an R package which provides an extensive collection of data formatting and processing, filtering, visualization, and sample and group comparison functionalities. The package provides a suite of plotting methods and enables expedient, flexible and interactive visualization of complex datasets through functions which link to a powerful and interactive visualization user interface, Trelliscope. Example analysis using FT-MS data from a soil microbiology study demonstrates the core functionality of the package and highlights the capabilities for producing interactive visualizations.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2025

Tailoring a 3D Covalent Organic Framework Toward Facile Functionalization

Three-dimensional covalent organic frameworks (3D COFs) are notably crystalline and stable, but their architectures and monomer structures make them difficult to functionalize. Here, a new strategy is presented to render COF-300 and other imine-linked frameworks amenable to facile functionalization in the last step of synthesis. By reducing the imine linkages to secondary amines and appending them with acetyl halide groups, the linkages are converted to electrophiles that can be readily reacted with nucleophilic guests. This route yields eight new COF-300 derivatives, bearing chloroacetyl, bromoacetyl, azide, cyano, amino, hydroxyl, methoxy, or thiomethyl groups appended to the inter-monomer linkages. The new materials are characterized through solid-state NMR, infrared spectroscopy, and powder X-ray diffraction, among other techniques, finding that the reported linkage transformations proceed to complete conversion while retaining the crystallinity of the materials. Microcrystal electron diffraction (microED) data are used to solve the evacuated structure of the amine-linked framework COF-300-AR for the first time, providing conclusive evidence of this framework's guest-induced phase change, along with the structure of the new framework COF-300-NH 2 . Finally, COF-300-NH 2 is shown to have significantly improved adsorption capacity for CO 2 and perfluoroalkyl substances (PFAS), highlighting the benefits of this synthetic strategy for the generation of customized adsorbents.

COF-300↗

DOE OSTI2013

Framework for assessing impacts of pile-driving noise from offshore wind farm construction on a harbour seal population

Offshore wind farm developments may impact protected marine mammal populations, requiring appropriate assessment under the EU Habitats Directive. We describe a framework developed to assess population level impacts of disturbance from piling noise on a protected harbour seal population in the vicinity of proposed wind farm developments in NE Scotland. Spatial patterns of seal distribution and received noise levels are integrated with available data on the potential impacts of noise to predict how many individuals are displaced or experience auditory injury. Expert judgement is used to link these impacts to changes in vital rates and applied to population models that compare population changes under baseline and construction scenarios over a 25 year period. We use published data and hypothetical piling scenarios to illustrate how the assessment framework has been used to support environmental assessments, explore the sensitivity of the framework to key assumptions, and discuss its potential application to other populations of marine mammals. -- Highlights: • We develop a framework to support Appropriate Assessment for harbour seal populations. • We assessed potential impacts of wind farm construction noise. • Data on distribution of seals and noise were used to predict effects on individuals. • Expert judgement linked these impacts to vital rates to model population change. • We explore the sensitivity of the framework to key assumptions and uncertainties.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

Galaxy zoo builder: Morphological dependence of spiral galaxy pitch angle

ABSTRACT Spiral structure is ubiquitous in the Universe, and the pitch angle of arms in spiral galaxies provide an important observable in efforts to discriminate between different mechanisms of spiral arm formation and evolution. In this paper, we present a hierarchical Bayesian approach to galaxy pitch angle determination, using spiral arm data obtained through the Galaxy Builder citizen science project. We present a new approach to deal with the large variations in pitch angle between different arms in a single galaxy, which obtains full posterior distributions on parameters. We make use of our pitch angles to examine previously reported links between bulge and bar strength and pitch angle, finding no correlation in our data (with a caveat that we use observational proxies for both bulge size and bar strength which differ from other work). We test a recent model for spiral arm winding, which predicts uniformity of the cotangent of pitch angle between some unknown upper and lower limits, finding our observations are consistent with this model of transient and recurrent spiral pitch angle as long as the pitch angle at which most winding spirals dissipate or disappear is larger than 10°.

Lingard, Timothy↗

DOE OSTI2026

Hydrazinoacetic acid is a biosynthetic precursor of the bacterially produced nitramine, N -nitroglycine

Nitramines [R(R′)N–NO 2 ; R,R′=H or alkyl] are valuable synthetic products, but knowledge of the biosynthetic processes that generate these compounds is limited. This work sought to elucidate the biosynthesis of a nitramine natural product, N-nitroglycine (NNG) by Streptomyces noursei . Stable isotope studies showed that S. noursei cells supplemented with L-(ε- 15 N)lysine, ( 15 N)glycine, or ( 13 C)hydrazinoacetic acid (HAA) incorporated 67%, 88%, and 67% of the isotope label into NNG, respectively, indicating that these compounds are biosynthetic precursors of NNG. Liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) of 15 N-Lys-labeled NNG confirmed that the nitro nitrogen of NNG originates from Lys. Bioinformatics analysis of the S. noursei genome showed evidence for a biosynthetic gene cluster (BGC) that contained machinery for HAA biosynthesis ( nngKLM ), consistent with the results of the isotope labeling. In vitro reconstitution of the gene products produced HAA. The borders of this BGC were defined by cross-referencing the predicted BGC with previously published differential proteomics data. Furthermore, we show that azaserine is produced alongside NNG in S. noursei cultures, linking the two biosynthetic pathways via a proposed nitrosamine biosynthetic intermediate. Finally, the oxygen balance for NNG is −20.2% for the formation of carbon dioxide (CO 2 ), which is comparable to that of hexahydro-1,3,5- trinitro-1,3,5-triazene (common name: RDX; −21.6%). Crystal structure data of NNG indicate that the unit crystalizes as a pure material, not a hydrate, suggesting a favorable energetic crystallization phase. The combined results suggest a route that, with further development, could lead to sustainable production of energetic nitramines via synthetic biology or biocatalytic approaches.

biosynthesis↗