11,208 results match your criteria: "‡National Institute of Standards and Technology[Affiliation]"

Dynamics of residential indoor gas- and particle-phase water-soluble organic carbon: measurements during the CASA experiment.

Environ Sci Process Impacts

October 2024

Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.

Previous time-integrated (2 h to 4 h) measurements show that total gas-phase water-soluble organic carbon (WSOC) is 10 to 20 times higher inside homes compared to outside. However, concentration dynamics of WSOC and total particle phase WSOC (WSOC)-are not well understood. During the Chemical Assessment of Surfaces and Air (CASA) experiment, we measured concentration dynamics of WSOC and WSOC inside a residential test facility in the house background and during scripted activities.

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Proposed experiment to measure nonlinear optical susceptibilities in the saturated regime.

Phys Rev A (Coll Park)

August 2024

Quantum Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8410, USA.

When an optical beam passes through a thin slice of a homogeneous material, the change of its phase and amplitude is characterized by the material's linear and nonlinear susceptibility, the latter also known as the hyperpolarizability. The standard method for measuring the nonlinear susceptibility is the scan. This widely used method is sometimes applied outside of its range of validity, leading to systematic errors.

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A method is described to measure the thermal expansion coefficient of fused quartz glass. The measurement principle is to monitor the change in resonance frequency of a Fabry-Perot cavity as its temperature changes; the Fabry-Perot cavity is made from fused quartz glass. The standard uncertainty in the measurement was less than 0.

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  • Immunoassay test strips for detecting fentanyl and other drugs are widely used in various fields, but there is growing interest in expanding their application to test more substances like xylazine.
  • This study examines the effectiveness of test strips for seven drugs, focusing on their reproducibility, sensitivity, cross-reactivity, and how they perform after long storage at high temperatures.
  • The findings indicate that most strips remain effective and maintain sensitivity even when expired, though cross-reactivity with other compounds signals the need for careful consideration before using them in drug testing.
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With the lack of standardized validation protocols across the forensic chemistry community, validation of instrumentation can be a challenging and time-consuming task. However, this process is crucial to understanding the associated capabilities and limitations, especially for nascent technologies. Rapid GC-MS is one such emerging analytical technique being increasingly implemented in forensic laboratories due to its fast and informative screening capabilities.

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  • Standard information reporting is essential for consistent assay conditions and data, enabling easier comparisons between laboratories.
  • The publication presents the Minimum Information for Reporting on the TEER assay (MIRTA), a key method used to assess cell culture models and toxicity potential.
  • Developed through an international collaboration, the recommendations from the RespTox Collaborative aim to improve data transparency, reproducibility, and quality in both respiratory and other cell systems.
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Photothermal induced resonance (PTIR), also known as atomic force microscopy-infrared (AFM-IR), enables nanoscale IR absorption spectroscopy by transducing the local photothermal expansion and contraction of a sample with the tip of an atomic force microscope. PTIR spectra enable material identification at the nanoscale and can measure sample composition at depths >1 μm. However, implementation of quantitative, multivariate, nanoscale IR analysis requires an improved understanding of PTIR signal transduction and of the intensity dependence on sample characteristics and measurement parameters.

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  • Scientists from 34 labs in 19 countries worked together to measure certain fats (ceramides) in human blood using special techniques.
  • They used both standard methods and their own methods to get very accurate and consistent results.
  • The study helps improve future medical tests and treatments by providing reliable information about these fats in blood samples.
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Objective: This work presents an automated quality control (QC) system within quantitative MRI (qMRI) workflows. By leveraging the ISMRM/NIST quantitative MRI system phantom, we establish an open-source pipeline for rapid, repeatable, and accurate validation and stability tracking of sequence quantification performance across diverse clinical settings.

Materials And Methods: A microservice-based QC system for automated vial segmentation from quantitative maps was developed and tested across various MRF acquisition and protocol designs, with reports generated and returned to the scanner in real time.

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In this work, we extend vcfdist to be the first variant call benchmarking tool to jointly evaluate phased single-nucleotide polymorphisms (SNPs), small insertions/deletions (INDELs), and structural variants (SVs) for the whole genome. First, we find that a joint evaluation of small and structural variants uniformly reduces measured errors for SNPs (- 28.9%), INDELs (- 19.

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  • * The 1000 Genomes Project and Oxford Nanopore Technologies are working together to produce LRS data from at least 800 samples to enhance the identification of genetic variations and better understand human genetic diversity.
  • * Initial analysis of 100 samples shows high accuracy in detecting genetic variants, including structural variants that disrupt gene function, and provides valuable data for the clinical genetics community to advance research on pathogenic variations.
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Quantification Approaches in Non-Target LC/ESI/HRMS Analysis: An Interlaboratory Comparison.

Anal Chem

October 2024

Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16, 11418 Stockholm, Sweden.

Nontargeted screening (NTS) utilizing liquid chromatography electrospray ionization high-resolution mass spectrometry (LC/ESI/HRMS) is increasingly used to identify environmental contaminants. Major differences in the ionization efficiency of compounds in ESI/HRMS result in widely varying responses and complicate quantitative analysis. Despite an increasing number of methods for quantification without authentic standards in NTS, the approaches are evaluated on limited and diverse data sets with varying chemical coverage collected on different instruments, complicating an unbiased comparison.

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Influence of Density and Pressure on Glass Formation in the Kob-Andersen Model.

J Phys Chem B

October 2024

State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China.

Article Synopsis
  • The study investigates glass formation in the Kob-Andersen model across various densities and pressures, comparing it with recent research on polymeric glass-forming liquids to assess the "universality" of glass formation.
  • Key characteristics analyzed include structural relaxation time, self-diffusion coefficient, viscosity, characteristic temperatures, and fragility, aiming to identify material-specific features versus universal properties.
  • Findings suggest that the glassy dynamics of the Kob-Andersen model reflect significant trends also seen in polymeric liquids, indicating a notable "universality" in glass formation behaviors.
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The frequency stability of a laser locked to an optical reference cavity is fundamentally limited by thermal noise in the cavity length. These fluctuations are linked to material dissipation, which depends on both the temperature of the optical components and the material properties. Here, the design and experimental characterization of a sapphire optical cavity operated at 10 K with crystalline coatings at 1069 nm is presented.

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  • The Genome in a Bottle Consortium (GIAB) is creating matched tumor-normal samples that are publicly consented for sharing genomic data and cell lines, focusing on pancreatic ductal adenocarcinoma (PDAC).
  • They provide a comprehensive genomic dataset from the first individual, combining high-depth DNA from tumor and normal cells using advanced whole genome sequencing technologies.
  • This open-access resource aims to help develop benchmarks for detecting genetic variants in cancer, fostering innovation in genome measurement and analysis tools.
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Background: The citri red mite, Panonychus citri (McGregor), is an important citrus pest worldwide, causing enormous economic losses to citrus production. Bifenazate is a widely used acaricide for controlling P. citri.

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This study investigates the potential of antimicrobial peptides (AMPs) as alternatives to combat antibiotic resistance, with a focus on two AMPs containing unnatural amino acids (UAAs), E2-53R (16 AAs) and LE-54R (14 AAs). In both peptides, valine is replaced by norvaline (Nva), and tryptophan is replaced by 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic). Microbiological studies reveal their potent activity against both Gram-negative (G(-)) and Gram-positive (G(+)) bacteria without any toxicity to eukaryotic cells at test concentrations up to 32 μM.

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  • High-crystal-quality nanoferrites with short ligands, like oleic acid, have been found to improve sensitivity and spatial resolution in magnetic particle imaging (MPI) due to their ability to form uniaxial assemblies.
  • A one-pot thermal decomposition method was developed to create magnetic nano-objects (MNOs) that show strong magnetic interactions and reproducibility, with sizes ranging from 12 to 27 nm, affecting their response and chain formation capabilities.
  • The study revealed that these ferrite MNOs significantly enhance signal and spatial resolution compared to existing MPI tracers, with results indicating the importance of optimizing the frequency and field amplitude for effective imaging and thermal performance.
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Background: In previous publications, the Task Force on Reference Measurement System Implementation proposed a procedural approach combining a critical review of entries available in the Joint Committee on Traceability in Laboratory Medicine (JCTLM) database with a comparison of this information against analytical performance specifications for measurement uncertainty (MU) and applied it to a group of 13 measurands.

Content: Here we applied this approach to 17 additional measurands, of which measurements are frequently requested. The aims of the study were (a) to describe the main characteristics for implementing traceability and the potential to fulfill the maximum allowable MU (MAU) at the clinical sample level of certified reference materials and reference measurement procedures listed in the JCTLM database; (b) to discuss limitations and obstacles, if any, to the achievement of the required quality of laboratory measurements; and (c) to provide a gap analysis by highlighting what is still missing in the database.

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Superconducting transition-edge sensors (TES) have emerged as fascinating devices to detect broadband electromagnetic radiation with low thermal noise. The advent of metallic transition metal dichalcogenides, such as NbSe, has also created an impetus to understand their low-temperature properties, including superconductivity. Interestingly, NbSe-based sensor within the TES framework remains unexplored.

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On-Chip Synthesis of Quasi-2D Semimetals from Multi-Layer Chalcogenides.

Adv Mater

November 2024

Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA.

Reducing the dimensions of materials from three to two, or quasi-two, provides a fertile platform for exploring emergent quantum phenomena and developing next-generation electronic devices. However, growing high-quality, ultrathin, quasi2D materials in a templated fashion on an arbitrary substrate is challenging. Here, the study demonstrates a simple and reproducible on-chip approach for synthesizing non-layered, nanometer-thick, quasi-2D semimetals.

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Topological insulators (TI) and magnetic topological insulators (MTI) can apply highly efficient spin-orbit torque (SOT) and manipulate the magnetization with their unique topological surface states (TSS) with ultrahigh efficiency. Here, efficient SOT switching of a hard MTI, V-doped (Bi,Sb)Te (VBST), with a large coercive field that can prevent the influence of an external magnetic field, is demonstrated. A giant switched anomalous Hall resistance of 9.

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Metal-organic frameworks (MOFs) have shown promise in both capturing CO under flue gas conditions and converting it into valuable chemicals. However, the development of a single MOF capable of capturing and selectively converting CO has remained elusive due to a lack of a harmonious combination of selectivity, water stability, and reactivity. For example, Cu(I)-based MOFs are particularly effective for CO conversion, but they do not typically exhibit selective CO adsorption and often suffer from instability in the presence of air and moisture.

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Comment on "Cellular aggregation dictates universal spreading behaviour of a whole-blood drop on a paper strip".

J Colloid Interface Sci

January 2025

Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States; Department of Physics and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057, United States. Electronic address:

Laha et al. studied the diffusive behavior of a whole-blood drop on filter paper using the generalized capillary bundle model. However, some model parameters should be further refined to accurately reflect the physics involved in this diffusion process.

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Article Synopsis
  • Polymer-based dielectrics are facing challenges in meeting modern electronics demands, which has led to increased interest in new materials and processes, particularly polyelectrolyte complexes (PECs).
  • PECs offer strong dielectric insulation but previously faced processing limitations, restricting them to thin conformal films.
  • Recent advancements in vat photopolymerization have enabled the manufacturing of PECs in various shapes, leading to dielectrics with high breakdown strengths and customizable properties through different resin formulations and post-processing techniques.
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