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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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Biolayer Interferometry Assay for Cyclin-Dependent Kinase-Cyclin Association Reveals Diverse Effects of Cdk2 Inhibitors on Cyclin Binding Kinetics
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A Fluorescence Polarization Assay for Macrodomains Facilitates the Identification of Potent Inhibitors of the SARS-CoV-2 Macrodomain
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Natural diversity screening, assay development, and characterization of nylon-6 enzymatic depolymerization
Successes in biocatalytic polyester recycling have raised the possibility of deconstructing alternative polymers enzymatically, with polyamide (PA) being a logical target due to the array of amide-cleaving enzymes present in nature. Here, we screen 40 potential natural and engineered nylon-hydrolyzing enzymes (nylonases), using mass spectrometry to quantify eight compounds resulting from enzymatic nylon-6 (PA6) hydrolysis. Comparative time-course reactions incubated at 40-70 °C showcase enzyme-dependent variations in product distributions and extent of PA6 film depolymerization, with significant nylon deconstruction activity appearing rare. The most active nylonase, a NylC K variant we rationally thermostabilized (an N-terminal nucleophile (Ntn) hydrolase, NylC K -TS, T m = 87.4 °C, 16.4 °C higher than the wild-type), hydrolyzes 0.67 wt% of a PA6 film. Reactions fail to restart after fresh enzyme addition, indicating that substrate-based limitations, such as restricted enzyme access to hydrolysable bonds, prohibit more extensive deconstruction. Overall, this study expands our understanding of nylonase activity distribution, indicates that Ntn hydrolases may have the greatest potential for further development, and identifies key targets for progressing PA6 enzymatic depolymerization, including improving enzyme activity, product selectivity, and enhancing polymer accessibility.
Learning protein fitness models from evolutionary and assay-labeled data
Machine learning-based models of protein fitness typically learn from either unlabeled, evolutionarily related sequences or variant sequences with experimentally measured labels. For regimes where only limited experimental data are available, recent work has suggested methods for combining both sources of information. Toward that goal, we propose a simple combination approach that is competitive with, and on average outperforms more sophisticated methods. Our approach uses ridge regression on site-specific amino acid features combined with one probability density feature from modeling the evolutionary data. Within this approach, we find that a variational autoencoder-based probability density model showed the best overall performance, although any evolutionary density model can be used. Moreover, our analysis highlights the importance of systematic evaluations and sufficient baselines.
The effects of osmolytes on in vitro kinesin-microtubule motility assays
Kinesin-driven motility was shown to be adversely affected in a concentration dependent manner by the addition of osmolytes: glycerol, polyethylene glycol, and trimethylamine N -oxide.
Profiling rhythmicity of bile salt hydrolase activity in the gut lumen with a rapid fluorescence assay
24-hour rhythmicity in bile salt hydrolase activity levels is influenced by feeding patterns, providing a pathway for the gut microbiome to affect host peripheral circadian rhythmicity.
Gain-of-Signal Assays for Probing Inhibition of SARS-CoV-2 M[superscript pro]/3CL[superscript pro] i
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Nuclide Inventory Validation: Radiochemical Assay Data Quality and Modeling Challenges in Benchmark Models Development
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Isotope-selective radiography and material assay using high-brilliance, quasi-monochromatic, high-energy photons
We demonstrate the possibility to directly detect microgram amounts of the isotope 7 Li using a quasi-monochromatic high-energy photon beam. The isotope selective detection is based on a witness scatterer absorbing and re-emitting photons via nuclear resonance fluorescence. This enables the detection of isotopes with microgram accuracy at long distances from the actual sample. Further, we demonstrate that the technique can deliver quantitative information without specific knowledge of the photon flux and no spectral capabilities or knowledge of the resonance fluorescence cross section. Detection of low-atomic-weight isotopes screened by heavy shielding is also shown. The techniques described are applicable to all next-generation, ultrahigh brilliance, laser-Compton light sources currently under construction.
Nondestructive Assay for Nuclear Safeguards [Slides]
The objective of safeguards is the timely detection of diversion of significant quantities of nuclear material from peaceful nuclear activities to the manufacture of nuclear weapons. Currently, the IAEA is working to achieve universal acceptance of the AP, safeguards-by-design, unattended monitoring & data integration, and state-level concept/approach. We are trying to verify special nuclear material (SNM) is where it should be, and in the proper amount.
Nuclear Safeguards and Nondestructive Assay
Abstract not provided.
Nondestructive Assay for Nuclear Safeguards
Abstract not provided.
Lateral flow assay for detection of Yesinia pestis
The goal for this project is to create an accurate, deployable, and selective diagnostic tool for Yersinia pestis. Yersinia pestis is the causative agent of bubonic plague. One aspect of the pathogenic nature of Yersinia pestis comes from the F1 antigen. A major concern with Yersinia pestis is the ability to develop antibiotic resistance and become a deadly biothreat. A diagnostic tool for Yersinia pestis is imperative for national safety.
VITAL-Viral InhibiTors from ALgae: Generating Extracts for Antiviral Activity Assays
Algae from marine and extreme environments may provide novel compounds with antiviral activity for use in therapeutic drug development. We established a first effort combining experience and cultures used in biofuel research and from the Culture Collection of Microbes from Extreme Environments at PNNL. We generated a novel library of fractionated, algae-derived compounds for guiding research on small molecules in the environment and for the treatment of SARS-CoV-2 and other infectious diseases.
Destructive and Non-destructive Assay of Special Nuclear Material [Slides]
Abstract not provided.
Nondestructive Assay for Nuclear Safeguards [Slides]
Abstract not provided.
Nuclear Safeguards and Nondestructive Assay
What can we do? Encourage/ensure peaceful nuclear uses; Secure, safeguard, and/or dispose of dangerous nuclear and radiological material; Detect and control the proliferation of related WMD technology and expertise.