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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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DOE OSTI2025

Trinuclear gold chains and octanuclear copper gyrobifastigia stabilized using a fluorinated pyridyl ligand

The fluorinated pyridyl ligand [6-(CF 3 )-2-Py] − with gold( I ) affords trinuclear Au 3 assemblies that further organize into a supramolecular helical column through aurophilic interactions. Its chemistry with copper( I ) is even more remarkable, leading to an unprecedented octanuclear copper–pyridyl cluster complex featuring a central Cu 8 core with an approximate gyrobifastigium geometry. Solid powders of compounds {(6-(CF 3 )-2-Py)Au} 3 and {(6-(CF 3 )-2-Py)Cu} 8 exhibit intense photoluminescence at room temperature, displaying green and yellow colors to the naked eye, respectively. Here, the octanuclear copper complex is also an effective catalyst for azide–alkyne cycloaddition, producing triazoles. Detailed computational analyses confirm the preference for experimental geometries and provide insights into the observed luminescence.

Phan, Vo Quang Huy [University of Texas at Arlingt↗

DOE OSTI2024

Shadow of a laser beam

Light, being massless, casts no shadow; under ordinary circumstances, photons pass right through each other unimpeded. Here, we demonstrate a laser beam acting like an object — the beam casts a shadow upon a surface when the beam is illuminated by another light source. We observe a regular shadow in the sense it can be seen by the naked eye, it follows the contours of the surface it falls on, and it follows the position and shape of the object (the laser beam). Specifically, we use a nonlinear optical process involving four atomic levels of ruby. We are able to control the intensity of a transmitted laser beam by applying another perpendicular laser beam. We experimentally measure the dependence of the contrast of the shadow on the power of the laser beam, finding a maximum of approximately 22%, similar to that of a shadow of a tree on a sunny day. We provide a theoretical model that predicts the contrast of the shadow. This work opens new possibilities for fabrication, imaging, and illumination.

47 OTHER INSTRUMENTATION↗

DOE OSTI2024

Exabiome: Advancing Microbial Science through Exascale Computing

The Exabiome project seeks to improve the understanding of microbiomes through the development of methods for accelerating metagenomic science using exascale computing. This article gives an overview of scientific impact of the three components of the project: metagenome assembly, protein family detection, and comparative analysis of metagenomes. Exabiome developed MetaHipMer, the only metagenome assembler capable of scaling to full exascale systems. MetaHipMer has enabled ground-breaking assemblies on the Frontier supercomputer, with many scientific benefits, such as the discovery of rare species and viral genomes. To investigate protein families, Exabiome developed two exascale tools, PASTIS and HipMCL. Together, these can utilize exascale resources to understand the functional diversity of billions of dark matter proteins and novel protein families. For comparative analysis, Exabiome developed kmerprof, a tool that can be used to compare huge metagenomes for many different scientific purposes, for example, grouping human microbiomes according to body location.

59 BASIC BIOLOGICAL SCIENCES↗