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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 109 records · Page 6

Ultrafast Spectroscopy and Dynamics of Photoredox Catalysis

Photoredox catalysis has emerged as a powerful platform for chemical synthesis, utilizing chromophore excited states as selective energy stores to surmount chemical activation barriers toward making desirable products. Developments in this field have pushed synthetic chemists to design and discover new photocatalysts with novel and impactful photoreactivity but also with uncharacterized excited states and only an approximate mechanistic understanding. This review highlights specific instances in which ultrafast spectroscopies dissected the photophysical and photochemical dynamics of new classes of photoredox catalysts and their photochemical reactions. After briefly introducing the photophysical processes and ultrafast spectroscopic methods central to this topic, the review describes selected recent examples that evoke distinct classes of photoredox catalysts with demonstrated synthetic utility and ultrafast spectroscopic characterization. Furthermore, this review cements the significant role of ultrafast spectroscopy in modern photocatalyzed organic transformations and institutionalizes the developing intersection of synthetic organic chemistry and physical chemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Chemical Recommender System: Replacement Suggestions for Small Molecules

The Chemical Recommender System (CRS) is an open-source, high-performance toolkit that enables real-time similarity searches across the complete PubChem database (over 50 million molecules) using commodity hardware. The CRS addresses critical limitations in existing chemical informatics platforms through a novel vector database infrastructure, extensible model integration capabilities, and complete algorithmic transparency. The system implements a vector database deployment with partitioned indexing that achieves a ~60x speedup over traditional approaches. A containerized model integration framework allows researchers to seamlessly incorporate custom predictive models into the full-scale search and scoring pipeline, while complete configurability of search parameters, filtering logic, and scoring functions provides capabilities not available in existing black-box solutions. Beyond structural similarity, the CRS integrates OPERA QSAR models for thermophysical and toxicity predictions, RDKit synthetic accessibility scoring, and user-defined models to compute weighted final replacement scores. The complete system is accessible through an interactive web application supporting real-time progress monitoring, post-processing score re-weighting, automated PDF reporting, and batch processing capabilities.

Nair, Parthiv Anand [Sandia National Laboratories ↗

Reactor with advanced architecture for the electrochemical reaction of CO2, CO, and other chemical compounds

A platform technology that uses a novel membrane electrode assembly including a cathode layer comprising a reduction catalyst and a first anion-and-cation-conducting polymer, an anode layer comprising an oxidation catalyst and a cation-conducting polymer, a membrane layer comprising a cation-conducting polymer, the membrane layer arranged between the cathode layer and the anode layer and conductively connecting the cathode layer and the anode layer, in a COx reduction reactor has been developed. The reactor can be used to synthesize a broad range of carbon-based compounds from carbon dioxide.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Reactor with advanced architecture for the electrochemical reaction of CO2, CO and other chemical compounds

A platform technology that uses a novel membrane electrode assembly, including a cathode layer, an anode layer, a membrane layer arranged between the cathode layer and the anode layer, the membrane conductively connecting the cathode layer and the anode layer, in a COx reduction reactor has been developed. The reactor can be used to synthesize a broad range of carbon-based compounds from carbon dioxide and other gases containing carbon.

Kuhl, Kendra P.↗

Reactor with advanced architecture for the electrochemical reaction of CO2, CO, and other chemical compounds

A platform technology that uses a novel membrane electrode assembly including a cathode layer comprising a reduction catalyst and a first anion-and-cation-conducting polymer, an anode layer comprising an oxidation catalyst and a cation-conducting polymer, a membrane layer comprising a cation-conducting polymer, the membrane layer arranged between the cathode layer and the anode layer and conductively connecting the cathode layer and the anode layer, in a COx reduction reactor has been developed. The reactor can be used to synthesize a broad range of carbon-based compounds from carbon dioxide.

Kuhl, Kendra P.↗

Reactor with advanced architecture for the electrochemical reaction of CO2, CO and other chemical compounds

A platform technology that uses a novel membrane electrode assembly, including a cathode layer, an anode layer, a membrane layer arranged between the cathode layer and the anode layer, the membrane conductively connecting the cathode layer and the anode layer, in a CO x reduction reactor has been developed. The reactor can be used to synthesize a broad range of carbon-based compounds from carbon dioxide and other gases containing carbon.

Kuhl, Kendra P.↗

Autonomous Flow Electrochemistry for Accelerated Catalyst Discovery

Our objective is to develop an Autonomous Chemical Experimentation (ACE) platform that accelerates discovery of new catalytic transformations and other energy-relevant chemical reactions and processes. We intentionally designed ACE to be highly modular, both with respect to its rapid deployment to different chemistries and experimental workflows as well as incorporation of a wide range of different AI algorithms. In addition to the development of the core software architecture, initial efforts were made to incorporate Large Language Models to provide human-interpretable reasoning of the optimizer’s actions, and to develop a user-friendly graphical interface for experimental researchers. ACE was demonstrated using a flow electrocatalysis platform containing an inline FTIR spectrometer for real-time analysis and quantification of the reaction outcome. Human-in-the-loop experiments were performed in which a human researcher conducted an experiment using electrode potentials suggested by ACE, then fed the spectral data back to ACE for decision making. After confirming the successful function of the optimizer, efforts were next directed to automation of the hardware and performed full autonomy tests using three reactions: catalytic oxidation of formate, catalytic oxidation of cyclohexanol, and oxidation of hydroquinone. These studies confirm that ACE can close the loop between reaction execution, analysis, and optimization. They also reveal that more improved product detection methods will be essential for ACE to make well-informed decisions for reactions with low conversions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Massively parallel quantum chemical density matrix renormalization group method

Here, we present, to the best of our knowledge, the first attempt to exploit the supercomputer platform for quantum chemical density matrix renormalization group (QCDMRG) calculations. We have developed the parallel scheme based on the in-house MPI global memory library, which combines operator and symmetry sector parallelisms, and tested its performance on three different molecules, all typical candidates for QC-DMRG calculations. In case of the largest calculation, which is the nitrogenase FeMo cofactor cluster with the active space comprising 113 electrons in 76 orbitals and bond dimension equal to 6000, our parallel approach scales up to approximately 2000 CPU cores.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Retrobiosynthesis of unnatural lactams via reprogrammed polyketide synthase

Engineered polyketide synthases (PKSs) have great potential as biocatalysts. These unnatural enzymes are capable of synthesizing molecules that are either not amenable to biosynthesis or are extremely challenging to access chemically. PKSs can thus be a powerful platform to expand the chemical landscape beyond the limits of conventional metabolic engineering. Here we employ a retrobiosynthesis approach to design and construct PKSs to produce δ-valerolactam (VL) and three enantiopure α-substituted VL analogues that have no known biosynthetic route. We introduce the engineered PKSs and pathways for various malonyl-CoA derivatives into Pseudomonas putida and use proteomics, metabolomics and culture condition optimization to improve the production of our target compounds. These α-substituted VLs are polymerized into polyamides (nylon-5) or converted into their N-acryloyl derivatives. RAFT polymerization produces bio-derived polymers with potential biomedical applications. Overall, this interdisciplinary effort highlights the versatility and effectiveness of a PKS-based retrobiosynthesis approach in exploring and developing innovative biomaterials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Method for simultaneous characterization and expansion of reference libraries for small molecule identification

A variational autoencoder (VAE) has been developed to learn a continuous numerical, or latent, representation of molecular structure to expand reference libraries for small molecule identification. The VAE has been extended to include a chemical property decoder, trained as a multitask network, to shape the latent representation such that it assembles according to desired chemical properties. The approach is unique in its application to metabolomics and small molecule identification, focused on properties that are obtained from experimental measurements (m/z, CCS) paired with its training paradigm, which involves a cascade of transfer learning iterations. First, molecular representation is learned from a large dataset of structures with m/z labels. Next, in silico property values are used to continue training. Finally, the network is further refined by being trained with the experimental data. The trained network is used to predict chemical properties directly from structure and generate candidate structures with desired chemical properties. The network is extensible to other training data and molecular representations, and for use with other analytical platforms, for both chemical property and feature prediction as well as molecular structure generation.

Colby, Sean M.↗

The Pathway to a Safe and Effective Medication Formulary for Exploration Spaceflight

PURPOSE: Exploration space missions pose several challenges to providing a comprehensive medication formulary designed to accommodate the size and space limitations of the spacecraft; while addressing the individual medications needs and preferences of the Crew; the negative outcome of a degrading inventory over time, the inability to resupply before expiration dates; and the need to properly forecast the best possible medication candidates to treat conditions that will occur in the future. METHODS: The Pharmacotherapeutics Discipline has partnered with the Exploration Medical Capabilities (ExMC) Element to develop and propose a research pathway that is comprehensively focused on evidence-based models and theories, as well as on new diagnostic tools and treatments or preventive measures aimed at closure of the Med02 “Pharmacy” Gap; defined in the Human Research Program’s (HRP) risk-based research strategy. The Med02 Gap promotes the challenge to identify a strategy to ensure that medications used to treat medical conditions during exploration space missions are available, safe, and effective. It is abundantly clear that pharmaceutical intervention is an essential component of risk management planning for astronaut healthcare during exploration space. However, the quandary still remains of how to assemble a formulary that is comprehensive enough to prevent or treat anticipated medical events; and is also chemically stable, safe, and robust enough to have sufficient potency to last for the duration of an exploration space mission. In cases where that is not possible, addressing this Gap requires exploration of novel drug development techniques, dosage forms, and dosage delivery platforms that enhance chemical stability as well as therapeutic effectiveness. RESULTS: The proposed research pathway outlines the steps, processes, procedures, and a research portfolio aimed at identifying a capability that will provide a safe and effective pharmacy for any specific exploration Design Reference Mission (DRM). The proposed approach to building this research portfolio is to seek research projects that concentrate on four major focus areas; (1) Formulary selection, (2) Formulary potency and shelf life, (3) Formulary safety and toxicity, and (4) Novel technology and innovation such as portable real-time chemical analysis innovative drug therapies and dosage and delivery platforms. CONCLUSION: The research pathway has been completed and presented to the HRP. In spring 2017, it is scheduled to be reviewed by a panel of pharmaceutical and clinical experts that will evaluate the scientific merit and operational feasibility of the research pathway, as well as make suggestions for any warranted additions or improvements. Once finalized, the ExMC Element will proceed with the execution of this research pathway with the goal of gathering as much data, and learning as much as possible, to provide a safe and effective pharmaceutical formulary for use during exploration missions.

Daniels, V. R.↗

Chemically Recyclable and Tunable Polyolefin-Like Multiblock Copolymer Adhesives

Adhesives are important in creating multilayer products, such as in packaging and construction. Most current hot-melt adhesives such as poly(ethylene-co-vinyl acetate) (EVA) and polyurethanes lack chemical recyclability and do not easily de-bond, complicating recycling. Here, we achieved tunable adhesive properties of chemically recyclable polyolefin-like multiblock copolymers through regulating the incorporation of crystalline hard blocks, amorphous soft blocks, and ester content highlighted by adhesive strengths up to 6.80 MPa. We further demonstrated applications of these adhesives in multi-layer films and showed that the adhesives can be readily de-bonded, recovered, and chemically recycled. Overall, this study into structure-property relationships, including effects of crystallinity, soft-block incorporation, and ester content of the multiblock copolymers on adhesive properties, has resulted in a modular hot-melt adhesive platform that exhibits chemical recyclability for virgin-quality adhesive re-generation, reprocessability for repeated reuse of the recovered adhesive, and tunability for designing adhesives with a wide range of low to high (up to ~80% stronger than EVA) adhesion strengths.

36 MATERIALS SCIENCE↗

Advanced Algal Biofoundries for the Production of Polyurethane Precursors (CRADA Final Report)

The primary goal of the BEEPs project was to develop a process that could accelerate the development of algae as bioproduction platforms, from initial chemical product concept to an economically viable market supply. Under this program we elected to develop strains of algae that could generate polyurethane precursors, while simultaneously developing basic genetic tools to enable improved algal production systems. This program was specifically designed to incorporate National Laboratories as a means to utilize the expertise and facilities for new bioproduction platforms.

09 BIOMASS FUELS↗

Advanced Algal Biofoundries for the Production of Polyurethane Precursors

The primary goal of the BEEPs project was to develop a process that could accelerate the development of algae as bioproduction platforms, from initial chemical product concept to an economically viable market supply. Under this program we elected to develop strains of algae that could generate polyurethane precursors, while simultaneously developing basic genetic tools to enable improved algal production systems. This program was specifically designed to incorporate National Laboratories as a means to utilize the expertise and facilities for new bio-production platforms. To that end, we designed a program to collaborate with the Agile BioFoundry at Lawrence Berkeley National Laboratory (LBNL) and computational platforms at Pacific Northwest National Laboratory (PNNL). In addition to these National Laboratory partners, we also had academic partners from UC Davis and Georgia Tech, as well as commercial partners Algenesis Materials and BASF. To achieve these goals, we initially focused on developing the genetic tools and high throughput screening technologies necessary to generate and assess production of polymer precursors (succinic acid) in algae and cyanobacteria, including advanced promoters and biosensors. In parallel, we computationally identified potential production bottlenecks and then used the developed genetic tools to increase production rates and yields. Constant feedback of data was used in conjunction with machine learning, high-throughput cell sorting, and synthetic biology, for additional targeted metabolic engineering. Multiple rounds of tool design, building, testing, and learning were supplied to partners at PNNL and LBNL to develop new models and tools that could expedite bioproduction platform development and increase yield performance. We targeted, and achieved, the FOA requirement yield metric of 20 g/L, as a milestone and deliverable from at least one of our engineered strains for the production of succinic acid.

09 BIOMASS FUELS↗