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Miller, Lance Lee

Publications and source records attributed to Miller, Lance Lee.

13 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Evaluation of High Temperature Plastics as a Ceramic Replacement

This report describes the 2015-2017 fiscal year research efforts to evaluate high temperature plastics as replacement materials for ceramics in electrical contact assemblies. The main objective of this work was to assess the feasibility of replacing existing high-price ceramic inserts with a polymeric material. Current ceramic parts are expensive due to machining costs and can suffer brittle failure. Therefore, replacing the ceramic with a more cost-effective material — in this case a plastic — is highly desirable. Not only are plastics easier to process, but they can also eliminate final tooling and are less brittle than ceramics. This effort used a three-phase approach: selection of appropriate materials determined by a comprehensive literature review, performance of an initial thermal stability screening, understanding of aging behavior under normal and off-normal conditions, and evaluation of performance at elevated temperatures. Two polymers were determined to meet the desired criteria: polybenzimidazole, and Vespel® SP-1 polyimide. Polymer derived ceramics may also be useful but will require further development of molding capabilities that were beyond the scope of this program.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Isomer-sensitive deboronation in reductive aminations of aryl boronic acids

Deboronation is observed during the reductive amination of formylphenylboronic acid (FPBA) to the amine termini and side chains of peptides. This deboronation is sensitive to the isomerism of the boronic acid (BA), with ortho -FPBA yielding complete deboronation in the preparation of an N-terminally-modified dipeptide. The observed behavior is also clearly mediated by the chemical identity of the amine substrate. These results reveal a previously undocumented subtlety of BA functionalization and highlight the importance of thorough spectroscopic characterization in the preparation of peptide and small molecule BAs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

A multi-stimuli responive, self-assembling, boronic acid dipeptide

Modification of the dipeptide of phenylalanine, FF, with a boronic acid (BA) functionality imparts unique aqueous self-assembly behavior that responds to multiple stimuli. Changes in pH and ionic strength are used to trigger hydrogelation via the formation of nanoribbon networks. Thus, we show for the first time that the binding of polyols to the BA functionality can modulate a peptide between its assembled and disassembled states.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗