Development and Characterization of a Multimycotoxin Reference Material

2019 ◽  
Vol 102 (6) ◽  
pp. 1642-1650 ◽  
Author(s):  
Melissa M. Phillips ◽  
Tomás M. López Seal ◽  
Jennifer M. Ness ◽  
Kai Zhang
Keyword(s):  
Interlaboratory Comparison ◽  
Accurate Determination ◽  
Data Sets ◽  
Mass Fractions ◽  
Adequate Quality ◽  
Multiple Sample ◽  
Lc Tandem Ms ◽  
The U.S

Background: Matrix-matched reference materials (RMs) are critical for adequate quality assurance of extraction, digestion, separation, and/or detection processes for analytes of interest in foods and dietary supplements. The accurate determination of mycotoxins in foods is an international concern. While RMs for mycotoxins are available from a variety of RM producers, these mainly address a single mycotoxin or group of mycotoxins and therefore require the use of multiple RMs for multitarget methods. Objective: To address the increasing needs of laboratories moving toward LC-MS-based multimycotoxin analysis, the U.S. National Institute of Standards and Technology (NIST) collaborated with the U.S. Food and Drug Administration (FDA) to produce a naturally incurred RM for multiple mycotoxins in corn. Methods: Homogeneity of the RM has been assessed using a stratified random sampling of the final product based on mycotoxin mass fractions measured by the FDA and NIST. Multiple sample sizes were evaluated to maximize homogeneity in the obtained results. The mycotoxin levels in the final materials have been evaluated via interlaboratory comparison and isotope dilution LC–tandem MS measurements made at the FDA and NIST. The final value assignment combined results from these data sets. Conclusions: The study successfully developed a certified RM, SRM 1565 Mycotoxins in Corn, and a workflow for the future development of multimycotoxin RMs in different matrices.

Development and Characterization of a Multimycotoxin Reference Material

2019 ◽  
Vol 102 (6) ◽  
pp. 1642-1650 ◽  
Author(s):  
Melissa M Phillips ◽  
Tomás M López Seal ◽  
Jennifer M Ness ◽  
Kai Zhang
Keyword(s):  
Interlaboratory Comparison ◽  
Accurate Determination ◽  
Data Sets ◽  
Mass Fractions ◽  
Adequate Quality ◽  
Multiple Sample ◽  
Lc Tandem Ms ◽  
The U.S

Abstract Background: Matrix-matched reference materials (RMs) are critical for adequate quality assurance of extraction, digestion, separation, and/or detection processes for analytes of interest in foods and dietary supplements. The accurate determination of mycotoxins in foods is an international concern. While RMs for mycotoxins are available from a variety of RM producers, these mainly address a single mycotoxin or group of mycotoxins and therefore require the use of multiple RMs for multitarget methods. Objective: To address the increasing needs of laboratories moving toward LC-MS-based multimycotoxin analysis, the U.S. National Institute of Standards and Technology (NIST) collaborated with the U.S. Food and Drug Administration (FDA) to produce a naturally incurred RM for multiple mycotoxins in corn. Methods: Homogeneity of the RM has been assessed using a stratified random sampling of the final product based on mycotoxin mass fractions measured by the FDA and NIST. Multiple sample sizes were evaluated to maximize homogeneity in the obtained results. The mycotoxin levels in the final materials have been evaluated via interlaboratory comparison and isotope dilution LC–tandem MS measurements made at the FDA and NIST. The final value assignment combined results from these data sets. Conclusions: The study successfully developed a certified RM, SRM 1565 Mycotoxins in Corn, and a workflow for the future development of multimycotoxin RMs in different matrices.

scholarly journals Benchmark of Nanoparticle Tracking Analysis on Measuring Nanoparticle Sizing and Concentration

2017 ◽  
Vol 5 (4) ◽  
Author(s):  
Ciarán M. Maguire ◽  
Katherine Sillence ◽  
Matthias Roesslein ◽  
Claire Hannell ◽  
Guillaume Suarez ◽  
...  
Keyword(s):  
Interlaboratory Comparison ◽  
Track Length ◽  
Nanoparticle Tracking Analysis ◽  
Concentration Data ◽  
Liquid Suspension ◽  
Coefficients Of Variation ◽  
Multiple Sample ◽  
Research Facilities

One of the greatest challenges in the manufacturing and development of nanotechnologies is the requirement for robust, reliable, and accurate characterization data. Presented here are the results of an interlaboratory comparison (ILC) brought about through multiple rounds of engagement with NanoSight Malvern and ten pan-European research facilities. Following refinement of the nanoparticle tracking analysis (NTA) technique, the size and concentration characterization of nanoparticles in liquid suspension was proven to be robust and reproducible for multiple sample types in monomodal, binary, or multimodal mixtures. The limits of measurement were shown to exceed the 30–600 nm range (with all system models), with percentage coefficients of variation (% CV) being calculated as sub 5% for monodisperse samples. Particle size distributions were also improved through the incorporation of the finite track length adjustment (FTLA) algorithm, which most noticeably acts to improve the resolution of multimodal sample mixtures. The addition of a software correction to account for variations between instruments also dramatically increased the accuracy and reproducibility of concentration measurements. When combined, the advances brought about during the interlaboratory comparisons allow for the simultaneous determination of accurate and precise nanoparticle sizing and concentration data in one measurement.

scholarly journals Comparison of Elemental Analysis Techniques for the Characterization of Commercial Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 736
Author(s):  
Peter Seidel ◽  
Doreen Ebert ◽  
Robert Schinke ◽  
Robert Möckel ◽  
Simone Raatz ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Analytical Techniques ◽  
Optical Emission ◽  
Breakdown Spectroscopy ◽  
General Evaluation ◽  
Sample Composition ◽  
Laser Induced Breakdown ◽  
Copper Aluminum

Better quality control for alloy manufacturing and sorting of post-consumer scraps relies heavily on the accurate determination of their chemical composition. In recent decades, analytical techniques, such as X-ray fluorescence spectroscopy (XRF), laser-induced breakdown spectroscopy (LIBS), and spark optical emission spectroscopy (spark-OES), found widespread use in the metal industry, though only a few studies were published about the comparison of these techniques for commercially available alloys. Hence, we conducted a study on the evaluation of four analytical techniques (energy-dispersive XRF, wavelength-dispersive XRF, LIBS, and spark-OES) for the determination of metal sample composition. It focuses on the quantitative analysis of nine commercial alloys, representing the three most important alloy classes: copper, aluminum, and steel. First, spark-OES is proven to serve as a validation technique in the use of certified alloy reference samples. Following an examination of the lateral homogeneity by XRF, the results of the techniques are compared, and reasons for deviations are discussed. Finally, a more general evaluation of each technique with its capabilities and limitations is given, taking operation-relevant parameters, such as measurement speed and calibration effort, into account. This study shall serve as a guide for the routine use of these methods in metal producing and recycling industries.

scholarly journals Softening of Shear Elastic Coefficients in Shape Memory Alloys Near the Martensitic Transition: A Study by Laser-Based Resonant Ultrasound Spectroscopy

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1383
Author(s):  
Petr Sedlák ◽  
Michaela Janovská ◽  
Lucie Bodnárová ◽  
Oleg Heczko ◽  
Hanuš Seiner
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Single Crystals ◽  
Accurate Determination ◽  
Martensitic Transition ◽  
Elastic Coefficient ◽  
Resonant Ultrasound Spectroscopy ◽  
Resonant Ultrasound

We discuss the suitability of laser-based resonant ultrasound spectroscopy (RUS) for the characterization of soft shearing modes in single crystals of shape memory alloys that are close to the transition temperatures. We show, using a numerical simulation, that the RUS method enables the accurate determination of the c′ shear elastic coefficient, even for very strong anisotropy, and without being sensitive to misorientations of the used single crystal. Subsequently, we apply the RUS method to single crystals of three typical examples of shape memory alloys (Cu-Al-Ni, Ni-Mn-Ga, and NiTi), and discuss the advantages of using the laser-based contactless RUS arrangement for temperature-resolved measurements of elastic constants.

Local bond order parameters for accurate determination of crystal structures in two and three dimensions

2018 ◽  
Vol 20 (42) ◽  
pp. 27059-27068 ◽  
Author(s):  
Hossein Eslami ◽  
Parvin Sedaghat ◽  
Florian Müller-Plathe
Keyword(s):  
Crystal Structures ◽  
Bond Order ◽  
Accurate Determination ◽  
Three Dimensional ◽  
Order Parameters ◽  
Three Dimensions ◽  
Local Order ◽  
Crystalline Structures

Local order parameters for the characterization of liquid and different two- and three-dimensional crystalline structures are presented.

Characterization of Matrix-Assisted Laser Desorption Based on Absorption and Acoustic Monitoring

1995 ◽  
Vol 49 (12) ◽  
pp. 1826-1833 ◽  
Author(s):  
Jan Preisler ◽  
Edward S. Yeung
Keyword(s):  
Atmospheric Pressure ◽  
Accurate Determination ◽  
Optimal Conditions ◽  
Plume Velocity ◽  
Ion Laser ◽  
Optical Probing ◽  
Argon Ion ◽  
Reduced Pressures

Conventional methods for studying matrix-assisted desorption-ionization rely on mass spectroscopy. In this study, a 488-nm argon-ion laser beam is deflected by two acoustooptic deflectors to image plumes desorbed at atmospheric pressure via absorption. All species, including neutral molecules, are monitored. Interesting features, e.g., differences between the initial plume and subsequent plumes desorbed from the same spot, or the formation of two plumes from one laser shot, are observed. Total plume absorbance can be correlated with the acoustic signal generated by the desorption event. A model equation for the plume velocity as a function of time is proposed. Optical probing also enables accurate determination of plume velocities at reduced pressures. These results define the optimal conditions for desorbing analytes from matrices, as opposed to achieving a compromise between efficient desorption and efficient ionization as is practiced in mass spectrometry.

scholarly journals Characterization of Self-Heating Process in GaN-Based HEMTs

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1305 ◽  
Author(s):  
Daniel Gryglewski ◽  
Wojciech Wojtasiak ◽  
Eliana Kamińska ◽  
Anna Piotrowska
Keyword(s):  
Communication Systems ◽  
Accurate Determination ◽  
Heating Process ◽  
Equivalent Circuits ◽  
High Electron ◽  
Thermal Impedance ◽  
Self Heating ◽  
Gan Hemt

Thermal characterization of modern microwave power transistors such as high electron-mobility transistors based on gallium nitride (GaN-based HEMTs) is a critical challenge for the development of high-performance new generation wireless communication systems (LTE-A, 5G) and advanced radars (active electronically scanned array (AESA)). This is especially true for systems operating with variable-envelope signals where accurate determination of self-heating effects resulting from strong- and fast-changing power dissipated inside transistor is crucial. In this work, we have developed an advanced measurement system based on DeltaVGS method with implemented software enabling accurate determination of device channel temperature and thermal resistance. The methodology accounts for MIL-STD-750-3 standard but takes into account appropriate specific bias and timing conditions. Three types of GaN-based HEMTs were taken into consideration, namely commercially available GaN-on-SiC (CGH27015F and TGF2023-2-01) and GaN-on-Si (NPT2022) devices, as well as model GaN-on-GaN HEMT (T8). Their characteristics of thermal impedance, thermal time constants and thermal equivalent circuits were presented. Knowledge of thermal equivalent circuits and electro–thermal models can lead to improved design of GaN HEMT high-power amplifiers with account of instantaneous temperature variations for systems using variable-envelope signals. It can also expand their range of application.

Study of a-Si:H / c-Si Heterojunctions for PV Applications

1996 ◽  
Vol 420 ◽  
Author(s):  
F. Zignani ◽  
R. Galloni ◽  
R. Rizzoli ◽  
M. Ruth ◽  
C. Summonte ◽  
...  
Keyword(s):  
Gas Phase ◽  
Open Circuit Voltage ◽  
Accurate Determination ◽  
Electrical Characterization ◽  
Silicon Layer ◽  
Open Circuit ◽  
Hydrogen Dilution ◽  
Intrinsic Efficiency

Abstracta-Si:H / c-Si heterojunction diodes were produced by PECVD with varying amorphous silicon layer thickness and hydrogen dilution of the gas phase. An accurate determination of the growth rate also in the initial stages of the deposition was made possible by an original chemical method based on the dissolution of the films followed by spectroscopical analysis of the obtained solution.The electrical characterization of the diodes confirms the generation - recombination - multitunneling nature of the transport. Although H2 dilution is important, however, beyond a certain level it is detrimental for the junction quality, probably due to the transition to a microcrystalline phase deposition. Solar cells were also produced, the best results being an open circuit voltage of 610 mV and an intrinsic efficiency of 14.2%.

Direct Optical Estimation of Deformation Gradient Tensors Using Lucas-Kanade Digital Image Warping

2013 ◽  
Author(s):  
John J. Boyle ◽  
Guy M. Genin ◽  
Maiko Kume ◽  
Robert B. Pless ◽  
Stavros Thomopoulos
Keyword(s):  
Digital Image ◽  
Accurate Determination ◽  
Deformation Gradient ◽  
Biological Tissues ◽  
Magnetic Resonance Images ◽  
Image Correlation ◽  
Strain Fields ◽  
Established Technique

Mechanical characterization of inhomogeneous and/or geometrically complex biological tissues requires precise and accurate determination of strain fields. Digital image correlation is a well established technique for determining strain fields on the surfaces of deforming materials. The technique involves matching patterns between pairs of images to estimate the displacement of certain regions or features on a sample. 2 Image correlation has also been used to track deformations in dynamic magnetic resonance images of heart and brain. 3

scholarly journals A Street Graph-Based Morphometric Characterization of Two Large Urban Areas

2021 ◽  
Vol 13 (3) ◽  
pp. 1025
Author(s):  
Luca Salvadori ◽  
Maria Grazia Badas ◽  
Annalisa Di Bernardino ◽  
Giorgio Querzoli ◽  
Simone Ferrari
Keyword(s):  
Aspect Ratio ◽  
Urban Areas ◽  
Accurate Determination ◽  
Geometrical Parameters ◽  
Urban Microclimate ◽  
Area Index ◽  
Planar Area ◽  
Morphometric Characterization

Urban microclimate modelling, both numerical and in the laboratory, has strong implications in many relevant health and life-style management issues e.g., in studies for assessment and forecast of air quality (for both outdoor and, as boundary conditions, indoor investigations), for thermometric trend analysis in urban zones, in cultural heritage preservation, etc. Moreover, the study of urban microclimate modelling is largely promoted and encouraged by international institutions for its implication in human health protection. In the present work, we propose and discuss an adaptive street graph-based method aimed at automatically computing the geometrical parameters adopted in atmospheric turbulent flow modelling. This method has been applied to two real cases, the Italian cities of Rome and Cagliari, and its results has been compared with the ones from traditional methods based on regular grids. Results show that the proposed method leads to a more accurate determination of the urban canyon parameters (Canyon Aspect Ratio and Building Aspect Ratio) and morphometric parameters (Planar Area Index and Frontal Area Index) compared to traditional regular grid-based methods, at least for the tested cases. Further investigations on a larger number of different urban contexts are planned to thoroughly test and validate the proposed algorithm.

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