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Material Composition (material + composition)

Distribution by Scientific Domains

Polymers and Materials Science	40%
Chemistry	26%
Earth and Environmental Science	13%

Selected Abstracts

Accessing Time,Varying Forces on the Vibrating Tip of the Dynamic Atomic Force Microscope to Map Material Composition

ISRAEL JOURNAL OF CHEMISTRY, Issue 2 2008
Ozgur Sahin
In dynamic atomic force microscopes the primary physical quantities being measured are the amplitude/phase or amplitude/frequency of the vibrating force probe. Topographic images with spatial resolutions down to the atomic scale can be obtained by mapping these measurements across the sample surface under feedback control. During the imaging process the vibrating tip is observing tip,sample interaction potentials (force,distance relationships) at every point on the surface. The interaction potential is a superposition of short- and long,distance interactions of various origins determined by the material compositions of the tip, sample, and the medium of imaging. In principle, measurement of tip,sample interaction potential should allow determination and mapping of material composition of the sample. However, a single measurement of amplitude/phase or amplitude/frequency in dynamic atomic force microscopes is not enough to characterize a complicated tip,sample interaction potential. Recent developments in the understanding of dynamics of the vibrating force probe (cantilever), together with specially designed cantilevers that utilize torsional vibrations in addition to conventional vertical vibrations, enable the recovery of tip,sample interaction potentials at a timescale less than a millisecond. Here, with theory and experiments, we discuss how these cantilevers recover the information about the tip,sample interaction forces and give an example of compositional mapping on a polymeric material system. [source]

Qualitative and quantitative fracture analyses of high-strength ceramics

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2009
Marit Øilo
The aims of this study were to assess the applicability and repeatability of qualitative and quantitative analyses of the fracture patterns of four different high-strength ceramics. Ten bar-shaped specimens of four high-strength ceramics with different material composition and fabrication methods had been fractured by three-point bending in water (n = 40). Commonly used fractographic patterns for brittle materials, such as mirror and mist, were used to characterize and quantify the fractured surfaces of these specimens. The analyses were performed twice, on separate occasions, by the same operator. Assessment of the association between fractographic patterns and fracture stress was carried out, and repeatability assessments of the measurements were performed. The fracture initiator site and the common fractographic markers surrounding this site were found in all specimens. Statistically significant correlations were found between certain fracture patterns and stress at fracture. The repeatability of the measurements of the different fractographic patterns varied among the materials. Fracture analyses seem applicable as a tool to determine the fracture initiation site and to estimate the force vectors involved in the fracture of dental high-strength ceramics. [source]

Using soil knowledge for the evaluation of mid-infrared diffuse reflectance spectroscopy for predicting soil physical and mechanical properties

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2008
B. Minasny
Summary Mid-infrared diffuse reflectance spectroscopy can provide rapid, cheap and relatively accurate predictions for a number of soil properties. Most studies have found that it is possible to estimate chemical properties that are related to surface and solid material composition. This paper focuses on prediction of physical and mechanical properties, with emphasis on the elucidation of possible mechanisms of prediction. Soil physical properties that are based on pore-space relationships such as bulk density, water retention and hydraulic conductivity cannot be predicted well using MIR spectroscopy. Hydraulic conductivity was measured using a tension-disc permeameter, excluding the macropore effect, but MIR spectroscopy did not give a good prediction. Properties based on the soil solid composition and surfaces such as clay content and shrink-swell potential can be predicted reasonably well. Macro-aggregate stability in water can be predicted reasonably as it has a strong correlation with carbon content in the soil. We found that most of the physical and mechanical properties can be related back to the fundamental soil properties such as clay content, carbon content, cation exchange capacity and bulk density. These connections have been explored previously in pedotransfer functions studies. The concept of a spectral soil inference system is reiterated: linking the spectra to basic soil properties and connecting basic soil properties to other functional soil properties via pedotransfer functions. [source]

Net Shape Reaction Bonded Ceramic Micro Parts by Mechanical Microstructuring

ADVANCED ENGINEERING MATERIALS, Issue 10 2006
H.-J. Ritzhaupt-Kleissl
Net shape ceramic micro components can be realized by mechanical microstructuring green blanks consisting of precursor materials followed by reaction bonding. The precursor material is composed of mainly zirconium silicide as reactive precursor material, organosilicon polymer (PMSS) as low loss binder and zirconium oxide as an inert phase. Shaping in the green state can easily be performed by micro milling, even if different cutting strategies are applied. Subsequently the components are thermally processed for ceramization and for sintering them to full density. Dependent on the material composition and on the green density the dimensions of the sintered components are retained unchanged compared to the dimensions of the green parts. [source]

Simultaneous IR Material Recognition and Conductivity Mapping by Nanoscale Near-Field Microscopy,

ADVANCED MATERIALS, Issue 17 2007
J. Huber
IR scattering-type near-field microscopy is applied to simultaneously map material composition and conduction properties in cross-sectional samples of industrial bipolar and metal-oxide- semiconductor devices with nanoscale spatial resolution. Within a single mid-IR image, all relevant materials such as metals, Si, Si3N4, and oxides can be identified by material-specific amplitude and phase contrasts. [source]

Accessing Time,Varying Forces on the Vibrating Tip of the Dynamic Atomic Force Microscope to Map Material Composition

Proper Assessment of the JFK Assassination Bullet Lead Evidence from Metallurgical and Statistical Perspectives

JOURNAL OF FORENSIC SCIENCES, Issue 4 2006
Erik Randich Ph.D.
ABSTRACT: The bullet evidence in the JFK assassination investigation was reexamined from metallurgical and statistical standpoints. The questioned specimens are comprised of soft lead, possibly from full-metal-jacketed Mannlicher-Carcano (MC), 6.5-mm ammunition. During lead refining, contaminant elements are removed to specified levels for a desired alloy or composition. Microsegregation of trace and minor elements during lead casting and processing can account for the experimental variabilities measured in various evidentiary and comparison samples by laboratory analysts. Thus, elevated concentrations of antimony and copper at crystallographic grain boundaries, the widely varying sizes of grains in MC bullet lead, and the 5,60 mg bullet samples analyzed for assassination intelligence effectively resulted in operational sampling error for the analyses. This deficiency was not considered in the original data interpretation and resulted in an invalid conclusion in favor of the single-bullet theory of the assassination. Alternate statistical calculations, based on the historic analytical data, incorporating weighted averaging and propagation of experimental uncertainties also considerably weaken support for the single-bullet theory. In effect, this assessment of the material composition of the lead specimens from the assassination concludes that the extant evidence is consistent with any number between two and five rounds fired in Dealey Plaza during the shooting. [source]

Middle school students' beliefs about matter

JOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 5 2005
Mary B. Nakhleh
The objective of this study was to examine middle school students' developing understanding of the nature of matter and to compare middle school students' ideas to those of elementary schools students, as was done by Nakhleh and Samarapungavan [J Res Sci Teach 36(7):777,805, 1999]. Nine middle school students were interviewed using a scripted, semistructured interview. The interview probed students' understanding of the composition and particulate (atomic/molecular) structure of a variety of material substances; the relationship between particulate structure and macroscopic properties such as fluidity and malleability; as well as understanding of processes such as phase transition and dissolving. The results indicate that most of the middle school students interviewed knew that matter was composed of atoms and molecules and some of them were able to use this knowledge to explain some processes such as phase transitions of water. In contrast, almost no elementary students knew that matter was composed of atoms and molecules. However, the middle school students were unable to consistently explain material properties or processes based on their knowledge of material composition. In contrast to elementary school students, who had scientifically inaccurate but relatively consistent (macrocontinuous or macroparticulate) knowledge frameworks, the middle school students could not be classified as having consistent knowledge frameworks because their ideas were very fragmented. The fragmentation of middle school students' ideas about matter probably reflects the difficulty of assimilating the microscopic level scientific knowledge acquired through formal instruction into students' initial macroscopic knowledge frameworks. © 2005 Wiley Periodicals, Inc. [source]

Subcoercive Cyclic Electrical Loading of Lead Zirconate Titanate Ceramics II: Time-Resolved X-Ray Diffraction

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2009
Abhijit Pramanick
Structural changes such as non-180° domain wall motion and lattice strains in Pb(Zr,Ti)O3 ceramics are measured during the application of subcoercive cyclic electric fields using time-resolved high-energy X-ray diffraction with a stroboscopic data collection technique. The contributions to the electric-field-induced strains from non-180° domain wall motion and lattice distortions are determined as a function of material composition and type of dopant. For the different compositions studied, the largest strains due to non-180° domain wall motion are measured for La-doped tetragonal ceramics with a composition close to the morphotropic phase boundary. It is further observed that strain contributions from both non-180° domain wall motion and lattice distortions can be nonlinear with respect to the applied electric field. The correlation between the electric-field-induced structural changes and the macroscopic piezoelectric properties is discussed. [source]

Wood/plastic composites co-extruded with multi-walled carbon nanotube-filled rigid poly(vinyl chloride) cap layer

POLYMER INTERNATIONAL, Issue 5 2010
Shan Jin
Abstract Wood/plastic composites (WPCs) can absorb moisture in a humid environment due to the hydrophilic nature of the wood in the composites, making products susceptible to microbial growth and loss of mechanical properties. Co-extruding a poly(vinyl chloride) (PVC)-rich cap layer on a WPC significantly reduces the moisture uptake rate, increases the flexural strength but, most importantly, decreases the flexural modulus compared to uncapped WPCs. A two-level factorial design was used to develop regression models evaluating the statistical effects of material compositions and a processing condition on the flexural properties of co-extruded rigid PVC/wood flour composites with the ultimate goal of producing co-extruded composites with better flexural properties than uncapped WPCs. Material composition variables included wood flour content in the core layer and carbon nanotube (CNT) content in the cap layer of the co-extruded composites, with the processing temperature profile for the core layer as the only processing condition variable. Fusion tests were carried out to understand the effects of the material compositions and processing condition on the flexural properties. Regression models indicated all main effects and two powerful interaction effects (processing temperature/wood flour content and wood flour content/CNT content interactions) as statistically significant. Factors leading to a fast fusion of the PVC/wood flour composites in the core layer, i.e. low wood flour content and high processing temperature, were effective material composition and processing condition parameters for improving the flexural properties of co-extruded composites. Reinforcing the cap layer with CNTs also produced a significant improvement in the flexural properties of the co-extruded composites, insensitive to the core layer composition and the processing temperature condition. Copyright © 2009 Society of Chemical Industry [source]

Identification of Five Stages of Dike Swarms in the Shanxi-Hebei-Inner Mongolia Border Area and Its Tectonic Implications

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2004
SHAO Ji'an
Abstract Dike swarms are generally ascribed to intrusion of mantle-source magma result from extension. Basic dike swarms around the Shanxi-Hebei-Inner Mogolia borders in the northern peripheral area of the North China Craton can be divided into five age groups according to isotopic dating: 1800,1700 Ma, 800,700 Ma, 230 Ma, 140,120 Ma, and 50,40 Ma. Geological, petrological and isotope geochemical features of the five groups is investigated in order to explore the variation of the mantle material composition in the concerned area with time. And the various extensional activities reflected by the five groups of dike swarms are compared with some important tectonic events within the North China Craton as well as around the world during the same period. [source]

Functionally Graded Layers Prepared by Atmospheric Plasma Spraying for Solid Oxide Fuel Cells,

ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009
W. S. Xia
Two functionally graded layers between the electrolyte and adjacent electrodes were prepared by atmospheric plasma spraying (APS) for solid oxide fuel cells (SOFCs). Both the porosity and material compositions gradually vary in the two graded layers. The SOFC with the graded layers has higher electronic conductivity and far lower interface resistance than that without graded layers. [source]

Accessing Time,Varying Forces on the Vibrating Tip of the Dynamic Atomic Force Microscope to Map Material Composition

Wood/plastic composites co-extruded with multi-walled carbon nanotube-filled rigid poly(vinyl chloride) cap layer

Reliable hot-spot classification in 10,ms using ultra-fast lock-in thermography

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2009
Martin Kasemann
Abstract We propose and demonstrate a reliable and non-destructive spatially resolved measurement technique for ultra-fast hot-spot classification of solar cells. The method can deliver quantitative images of the local heat dissipation in hot-spots in measurement times below 10,ms. The high accuracy and sensitivity allow for reliable hot-spot testing and provide the basis for a reliable classification of solar cells into different hot-spot categories. The method can be applied to wafer-based silicon solar cells and in principle also to thin-film solar cells of all material compositions. This paper explains the measurement principle, gives a detailed step-by-step description of viable automated evaluation procedures, and assesses the sensitivity and accuracy of the method. Copyright © 2009 John Wiley & Sons, Ltd. [source]