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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Mass measurement systems and related methods for measuring mass of solids within a liquid

A measurement system includes a vessel for containing a fluid and at least one solid material and a probe assembly for disposing partially into the fluid within the vessel. The probe assembly includes a hollow tube having an open lower longitudinal end and at least one pressure sensor within the hollow tube, the at least one pressure sensor configured to measure pressures of the fluid within the hollow tube at at least two different elevations. A method of measuring a mass of suspended solids within a fluid, the method includes receiving pressure measurements representing two different elevations of the fluid within a hollow tube and substantially free of the suspended solids and based at least partially on the received pressure measurements, determining a mass of the suspended solids.

Galbreth, Gregory G.↗
DOE OSTI2022

Scalable Frontal Oligomerization: Insights from Advanced Mass Analysis

Linear oligomers of dicyclopentadiene (DCPD) are reactive precursors for thermoplastic and thermoset materials. Unlike the foul-smelling parent monomer, oligomers composed of DCPD are odorless. With appropriate modification of the end-group or backbone chemistry, telechelic DCPD oligomers have potential utility as cross-linkers and as macromonomer precursors for block and graft copolymers. Most existing methods to produce oligo-DCPD, however, require solvent, are relatively slow, and necessitate air-free techniques. Here we show that frontal ring-opening metathesis oligomerization (FROMO) of neat DCPD and other norbornene derivatives rapidly generates hundreds of grams of material in minutes with catalyst loadings of 0.5 mM. This energy-efficient catalytic process utilizes the heat generated by the reaction to self-propagate oligomerization throughout the liquid monomer. FROMO employs a terminal olefin (e.g., styrene) in which a cross-metathesis reaction (i.e., chain transfer) competes with ring-opening metathesis (i.e., propagation). Kendrick mass analysis enables rapid identification and assignment of all the chain-end types present and quantifies the degree of branching resulting from the infrequent cyclopentene ring-opening reaction. This analytical technique also detects oligomer species derived from trace impurities in the monomer or chain-transfer agent that are otherwise difficult to observe with other characterization methods. Here, the obtained oligomers possess well-defined chain-ends and molecular weight distributions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

String Theory Bounds on the Cosmological Constant, the Higgs Mass, and the Quark and Lepton Masses

In this paper, we elaborate on the new understanding of the cosmological constant and the gauge hierarchy problems in the context of string theory in its metastring formulation, based on the concepts of modular spacetime and Born geometry. The interplay of phase space (and Born geometry), the Bekenstein bound, the mixing between ultraviolet (UV) and infrared (IR) physics and modular invariance in string theory is emphasized. This new viewpoint is fundamentally rooted in quantum contextuality and not in statistical observer bias (anthropic principle). We also discuss the extension of this point of view to the problem of masses of quarks and leptons and their respective mixing matrices.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Meeting Report on the 3rd Chinese American Society for Mass Spectrometry Conference—Advancing Biological and Pharmaceutical Mass Spectrometry

Following the highly successful Chinese American Society for Mass Spectrometry (CASMS) conferences in the previous 2 years, the 3rd CASMS Conference was held virtually on August 28–31, 2023, using the Gather. Town platform to bring together scientists in the MS field. The conference offered a 4-day agenda with a scientific program consisting of two plenary lectures, and 14 parallel symposia in which a total of 70 speakers presented technological innovations and their applications in proteomics and biological MS and metabo-lipidomics and pharmaceutical MS. In addition, 16 invited speakers/panelists presented at two research-focused and three career development workshops. Moreover, 86 posters, 12 lightning talks, 3 sponsored workshops, and 11 exhibitions were presented, from which 9 poster awards and 2 lightning talk awards were selected. Furthermore, the conference featured four young investigator awardees to highlight early-career achievements in MS from our society. In conclusion, the conference provided a unique scientific platform for young scientists (i.e. graduate students, postdocs, and junior faculty/investigators) to present their research, meet with prominent scientists, learn about career development, and job opportunities (http://casms.org).

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2020

Vacuum Pyrolysis of Hybrid Poplar Milled Wood Lignin with Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry Analysis of Feedstock and Products for the Elucidation of Reaction Mechanisms

The pyrolysis of lignocellulosic materials is a promising technique to produce fuels and chemicals. It is well known that the most abundant products of lignin pyrolysis are oligomeric molecules, known as pyrolytic lignin (PL). The chemical composition of PL has been extensively studied; however, there is still an important debate whether these oligomers are produced directly from the lignin or from the recombination of monomeric pyrolytic products. Existing theories are unable to describe the effect of vacuum on the distribution of pyrolysis products. Hybrid poplar milled wood lignin (MWL) was initially isolated and thoroughly characterized by Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). Chemical formulas were assigned to each oligomeric compound detected. The MWL was also subjected to vacuum pyrolysis in a modified pyroprobe at 250, 750, and 1000 mbar (absolute pressure), and the resulting liquid products were analyzed by FT-ICR MS. A new strategy to assign structural representations to the oligomeric PL products is proposed, based on the plausible pyrolysis reaction mechanisms of depolymerization/fragmentation applied to original MWL oligomer formulas. Our results support the hypothesis that PL is formed from the removal of moieties from primary lignin pyrolysis products with between three and five aromatic rings. This depolymerization/fragmentation allows the oligomers to reduce their molecular weights to the point where they can be removed from the reaction zone by direct vaporization. Furthermore, this phenomenon highlights the importance of pressure on removal mechanisms and their impact on the molecular weight of the resulting products from lignin pyrolysis.

09 BIOMASS FUELS↗
DOE OSTI2022

Simultaneous Insight into Dissolution and Aggregation of Metal Sulfide Nanoparticles through Single-Particle Inductively Coupled Plasma Mass Spectrometry

Nanoparticles (NPs) and their colloidal aggregates are ubiquitous and play important roles in the transport and release of metals. Knowledge of their dissolution rates and aggregation behavior in solution are crucial for better prediction of their fate in biogeochemical cycling, ecotoxicity, and environmental remediation. There are however significant technical challenges to accurately obtain such information as a result of the heterogeneity and highly dynamic transformation exhibited by NPs, particularly at relatively low particle concentrations in aqueous systems. Here, we quantitatively examine the simultaneous dissolution and aggregation behavior of metal sulfide NPs using single-particle inductively coupled plasma mass spectrometry (spICP–MS). We focus on nickel sulfide (NiS), with additional data presented for copper sulfide (CuS) and cobalt sulfide (CoS). The kinetics of metal release (dissolution and disaggregation) of NiS was fastest under strongly oxidizing conditions (from 0.04 to >3 min –1 with H 2 O 2 ) and were slower under near-neutral (HEPES buffer/H 2 O) and acidic (1 mM HNO 3 ) conditions (≤0.006 min –1 ). Metal release kinetics in HNO 3 was not faster than in H 2 O or HEPES, suggesting that the solution pH has an influence over both the dissolution kinetics of individual particles and the NP aggregation states, which in combination affect metal release rates over time. Between different metal sulfides, the measured metal release rates were largely consistent with predictions based on the crystallinity, solubility products, and specific surface areas of the NPs, following an order of CoS > NiS > CuS. Here, the spICP–MS approach described here can be easily applied to the characterization of metal release and aggregation of other NPs at low concentrations (~10 5 particles/mL) typically found in natural environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Predator mass mortality events restructure food webs through trophic decoupling

Predators have a key role in structuring ecosystems. However, predator loss is accelerating globally, and predator mass-mortality events (MMEs)—rapid large-scale die-offs—are now emblematic of the Anthropocene epoch. Owing to their rare and unpredictable nature, we lack an understanding of how MMEs immediately impact ecosystems. Past predator-removal studies may be insufficient to understand the ecological consequences of MMEs because, in nature, dead predators decompose in situ and generate a resource pulse, which could alter ensuing ecosystem dynamics by temporarily enhancing productivity. Here we experimentally induce MMEs in tritrophic, freshwater lake food webs and report ecological dynamics that are distinct from predator losses or resource pulses alone, but that can be predicted from theory. MMEs led to the proliferation of diverse consumer and producer communities resulting from weakened top-down predator control and stronger bottom-up effects through predator decomposition. In contrast to predator removals alone, enhanced primary production after MMEs dampened the consumer community response. As a consequence, MMEs generated biomass dynamics that were most similar to those of undisturbed systems, indicating that they may be cryptic disturbances in nature. These biomass dynamics led to trophic decoupling, whereby the indirect beneficial effects of predators on primary producers are lost and later materialize as direct bottom-up effects that stimulate primary production amid intensified herbivory. Furthermore, these results reveal ecological signatures of MMEs and demonstrate the feasibility of forecasting novel ecological dynamics arising with intensifying global change.

Food webs↗
DOE OSTI2026

No Quantum Utility from Hadron Masses? No, Quantum Utility from Hadron Masses!

Is there a quantum utility in establishing the masses of hadrons? Here we show that the best response is that of Farrés, Capó, and Davis: perhaps, perhaps, perhaps. This is interesting given the general case that particle physics demands quantum computers. For stable hadrons, classical LQCD has achieved sub-percent precision with no sign problem, and quantum computers offer no advantage. For resonances, the Maiani-Testa theorem is an obstruction that quantum simulation is immune to. For nuclei, Wick contractions and signal-to-noise are genuine classical barriers. Underlying these cases is a unified picture connecting the sign problem to Wigner negativity and T gate cost. This manuscript was drafted from extensive interaction with \textsc{Claude}.

Lamm, Henry [Fermilab] (ORCID:0000000330330791)↗
DOE OSTI2023

2023 American Society for Mass Spectrometry (ASMS) 71st Annual Conference on Mass Spectrometry and Allied Topics

Title (20 words): The investigation of the mechanism for the water splitting by holmium oxide nitrate complex in gas-phase Introduction (120 words): The studies for hydrogen from water splitting is important for clean energy economy as molecular hydrogen is a potential energy carrier. Therefore, understanding the fundamental chemistry of water splitting is essential. The water splitting activated by [Ho(NO3)4]- was previously studied. The suggested mechanism was to first eliminate •NO2 from [Ho(NO3)4]- to make [HoO(NO3)3]-. Then, water was added to form [HoO(NO3)3(H2O)]-, followed by eliminating the •OH to form [HoOH(NO3)3]-. However, we proposed a new mechanism with the formation of [Ho(NO3)3]- prior to the water addition. Once water is added to this intermediate to make [Ho(NO3)3(H2O)]-, the •H is eliminated to form [HoOH(NO3)3]-. Here we have used a labeled experiments with 18-O nitrates. The results to support the new mechanism are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗