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Westmont, IL, United States

Niemeyer W.D.,McCrone Associates Inc.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

For forensic investigation in the food industry, scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray spectrometry (EDS) is a powerful, often non-destructive, instrumental analysis tool to provide information about: • Identification of inorganic (and some organic) materials found as foreign contaminants in food products returned by consumers or detected during quality control inspections in the production facilities • Identification of wear particles found in production lines • Distribution of materials within a matrix • Corrosion and failure analysis of production equipment The identification of materials by SEM/EDS is accomplished through a combination of morphology by SEM imaging and the elemental composition of the material by EDS. Typically, the EDS analysis provides a qualitative spectrum showing the elements present in the sample. Further analysis can be done to quantify the detected elements in order to further refine the material identification. Metal alloys can often be differentiated even within the same family such as 300 Series stainless steels. Glass types can be identified by the elemental composition where the detected elements are quantified as the oxides of each element. In this way, for example, common window glass is distinguishable from insulation glass used in many ovens. Wear particles or fragments from breakage can find their way into food products. SEM/EDS analysis of the materials is an important resource to utilize when trying to determine the original source. Suspected source materials can then be sampled for comparative analysis. EDS X-ray mapping is another tool that is available to provide information about the distribution of materials within a matrix. For example, the distribution of inorganic ingredients in a dried food helps to provide information about the grind and blend of the materials. © 2015 SPIE.

Karlinsey R.L.,Indiana Nanotech, Llc | Mackey A.C.,Indiana Nanotech, Llc | Dodge L.E.,Indiana Nanotech, Llc | Schwandt C.S.,McCrone Associates Inc.
Journal of Dentistry for Children | Year: 2014

Purpose: Fluoride varnishes are appealing topical fluoride preparations that may provide anticaries benefits. The purpose of this in vitro study was to assess the noncontact remineralization effects of a commercial 5% sodium fluoride varnish on white spot lesions (WSLs). Methods: Three-millimeter diameter enamel cores were extracted from bovine teeth, mounted in acrylic rods, ground and polished, and initially demineralized to create WSLs. Specimens were evaluated for surface microhardness and divided (n=6) into two groups (water control or noncontact 5% sodium fluoride white varnish with tricalcium phosphate, where one 0.50 ml unit dose was applied to acrylic rods instead of directly on WSLs). Groups were cycled in a three-day regimen consisting of two rounds of one-hour treatments and one-hour static immersions in demineralization solution. Between these events, WSLs were immersed in artificial saliva. Remineralization was evaluated using surface and cross-sectional microhardness and high-resolution scanning electron microscopy (SEM). Results: The noncontact varnish treatment produced significantly greater percent surface microhardness recoveries (P<.05) and smaller subsurface lesions compared to the control group (P<.05). SEM revealed comparatively greater WSL porosity reduction for noncontact varnish. Conclusions: Noncontact application of a commercial 5% sodium fluoride varnish reduced white spot lesion porosity and produced significant acid-resistant white spot lesion remineralization.

Niemeyer W.D.,McCrone Associates Inc.
Advanced Materials and Processes | Year: 2012

Identification and characterization of paint deficiencies and foreign contamination causing paint adhesion failures requires specialized analytical microscopy techniques. Adhesion failure of paint on automobiles can take several forms, such as flaking, peeling, and blistering, and can occur at the polymer interface or between paint layers. Once the cause of adhesion failure is determined, appropriate corrective actions can be implemented. Standard light microscopes are used to initially examine an adhesion failure. A polarized light microscope (PLM) equipped with polarizing filters for both transmitted and reflected light illumination provides some contrast enhancement and enables observation of crystalline materials. Fourier transform infrared (FTIR) microscopy is used to analyze, characterize, and identify organic materials isolated from the paint or substrate interface surfaces. A scanning electron microscope with an energy dispersive x-ray spectrometry accessory (SEM/EDS) provides elemental composition of materials and is typically used to identify inorganic materials.

Swider J.R.,McCrone Associates Inc.
Powder Diffraction | Year: 2010

The increasing use of microanalysis techniques to analyze particles has demanded more rapid phase identification methods for samples in the 10 μm size range. The XRD analysis of such particles is routinely accomplished using a Rigaku combination instrument combined with particle handling methods. Several case studies show the variety of material analysis problems that can be solved with this technique including identification of multiple mineral phases, corrosion components, and paint samples. © 2010 International Centre for Diffraction Data.

Schwandt C.S.,McCrone Associates Inc.
American Laboratory | Year: 2014

Materials in the form of particulate or engineered objects are relatively easy to characterize in terms of their composition, shape, size, and size distribution, provided they are larger than 1 ?m in average dimension. It is often assumed that nanometer-scale materials are just smaller versions of larger-sized materials made with the same precursors and procedures, but the chemical and physical interactions of submicrometer- or nanometer-scale materials are in fact different-offering new materials with novel properties. The very small scale of these new materials makes them very difficult to accurately characterize, and because of their unique properties, it is critical for materials scientists and engineers to conduct confirmatory analysis to verify the properties of their materials. Fortunately, advances in analytical instrumentation, especially field emission scanning electron microscopy (FESEM), permit characterization of submicrometer-sized materials. Several challenges need to be addressed in order to successfully accomplish a comprehensive, high-quality material characterization. These include: calibrating the scalar measurement tools of the FESEM, understanding the limitations of sample handling and preparation relative to other methods, the inability to use automated methods either in terms of image analysis software or other optical size distribution methods, and using crystal structural analysis to strengthen elemental analysis when small analysis volumes preclude standards for fully quantitative analysis.

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