Matrix Compositions Research Articles

Improving the High-Performance Inductively Coupled Plasma Optical Emission Spectrometry Methodology through Exact Matching

Exact matching is investigated as a means of improving high-performance inductively coupled plasma optical emission spectrometry (HP-ICP-OES), a technique developed at the National Institute of Standards and Technology (NIST) to enable elemental determinations with relative expanded uncertainty of approximately 0.2% expressed at 95% confidence. "Exact matching" refers to the very careful matching of analyte mass fractions, internal standard mass fractions, and matrix compositions among the calibration and unknown sample solutions prepared for an analysis. Computer spreadsheet modeling results and laboratory data involving 16 pairs of analyte and internal standard wavelengths show that exact matching of analyte and internal standard mass fractions mitigates imprecision and bias that can be caused by even subtle nonlinearity in the ICP-OES instrument response. Laboratory experiments also demonstrate matrix effects caused by small variations in acid composition and by mass fractions of Na less than 4 mg kg(-1), emphasizing the need for exact matching of matrix compositions. HP-ICP-OES analyses performed at NIST with and without exact matching illustrate that exact matching enables relative expanded uncertainties to be halved to approximately 0.1%.

Matrix compositions and the development of breast acini and ducts in 3D cultures

Breast epithelial cells develop into polarized and highly organized acinar and ductal structures in response to stromal cues, including extracellular matrix composition and density, which can in part be reproduced in 3D culture conditions. Here, we present the effects of various 3D in vitro stroma compositions (termed "matrices" or "substrates") on the ability of heterotypic cultures of epithelial and mesenchymal stem cells to organize into acinar and tubular structures. Normal murine mammary gland (NMuMG) cells were cultured, either alone or in combination (30:70) with mouse mesenchymal stem cells (D1), in 3D matrices generated by agarose, collagen, and Matrigel alone or by a combination thereof. After 3-5 d in culture, cell distribution, organization, and the presence of acinus-like and tubule-like structures were determined. The number of acinar structures was significantly higher in cultures grown in combination matrices of agarose with Matrigel or collagen I when compared with cultures grown in Matrigel or collagen I alone (p < 0.05). No tubular structures were formed when agarose was included in the matrix, regardless of the combination. In Matrigel, but not in collagen I/Matrigel microenvironment, the number of tubular structures was significantly increased in NMuMG/D1 coculture when compared with culture of NMuMG cells alone (p < 0.05). By immunohistochemical analysis, NMuMG cells cocultured with D1 cells were shown to form acinar structures with the NMuMG epithelial cells surrounding a lumen composed of dead cells while the D1 cells were mostly peripheral. Immunostaining for laminin indicated the presence of basement membrane when NMuMG cells were grown in Matrigel alone or cocultured with D1 cells in a combination of Matrigel and collagen I. These results indicate that the physical and biochemical properties of the matrix and cellular composition alter the organization of the mammary gland.

Highly Variable Contents of Phenolics in St. John’s Wort Products Affect Their Transport in the Human Intestinal Caco-2 Cell Model: Pharmaceutical and Biopharmaceutical Rationale for Product Standardization

The purposes of this study were to determine content uniformity of phenolics in the St. John's wort (SJW) supplements and to demonstrate how variations in the product matrices affect their absorption and efflux. LC and LC-MS/MS methods were used to determine the phenolic contents of 12 different products purchased locally or from the Internet. Three representative extracts were further submitted to Caco-2 cell transport experiment, and transport of rutin, hyperoside, and isoquercitrin was evaluated. The results indicated that the 12 different products displayed 12 different HPLC fingerprints, but all products contained the following major compounds: rutin, hyperoside, isoquercitrin, quercitrin, quercetin, and amentoflavone. The content uniformity of these major compounds was poor across products, with the smallest difference in the amounts of amentoflavone (3.6-fold) and largest difference in that of isoquercitrin (28.8-fold). The Caco-2 experiments indicated transport of rutin in products was vectorial, with the permeabilities varied about 3.6-fold in both directions of transport. The vectorial permeabilities of hyperoside and isoquercitrin were similarly different. Use of efflux transporter inhibitor studies suggested that MRP2 was involved in isoquercitrin's efflux and the product matrix affected the extent of its efflux. In conclusion, different SJW supplements had highly variable contents of phenolics, and the variability in product matrix and phytochemical compositions affected the permeabilities of key phenolics across the Caco-2 monolayers, which may further affect their bioavailabilities. Therefore, standardization will be necessary to ensure safe and efficacious using of supplements such as SJW.

Abstract 1001: Effects of matrix compositions on the development of breast acini and ducts in a 3D in-vitro culture model

Abstract Background: Epithelial cells of the breast respond to cues from the stromal components and develop into polarized and highly organized functional acinar and ductal structures. Extracellular matrix components and increased stiffness in particular have been shown to promote breast cancer. The stroma - cell interactions that determine the cellular organization and differentiation are in part reproduced in a 3D environment. Whether alterations of the microenvironment in 3D cultures could mimic phenotypic alterations observed during breast cancer progression remain to be fully determined. Here we present the effects of various stroma physical compositions on the ability of heterotypic 3D cultures of epithelial and mesenchymal stem cells to organize into acinar and tubular structures. Material &amp; Methods: The normal murine mammary gland (NMuMG) cells were cultured either alone or in combination (30:70) with mouse mesenchymal stem cells (D1), in 3D cell culture conditions generated by agarose, collagen and Matrigel® alone or a combination thereof. After 3-5 days in culture, cell distribution, organization and the presence of acinus-like and tubule-like structures were determined. Results: By immunohistochemistry, NMuMG cells co-cultured with D1 cells were shown to form acinar structures with the NMuMG epithelial cells surrounding a lumen composed of dead cells whereas the D1 cells were mostly peripheral. Immuno-staining for laminin indicated the presence of basement membrane when NMuMG cells were grown in Matrigel® alone or co-cultured with D1 cells in a combination of Matrigel® and collagen I. The number of acinar structures was significantly higher in cultures grown in combination of agarose with Matrigel® or collagen I when compared to the cultures grown in Matrigel® or collagen I alone (P&amp;lt;0.05). No tubular structures were formed when agarose was included in the matrix, regardless of the combination. In Matrigel® but not in collagen I/ Matrigel® microenvironment the number of tubular structures was significantly increased in NMuMG /D1 co-culture when compared to culture of NMuMG cells alone (P&amp;lt;0.05). Conclusion: These results indicate that the physical and biochemical properties of the matrix and cellular composition alter the organization of the mammary gland. Furthermore, they underline the likely critical role of the extracellular matrix in breast cancer progression. Supported by grants from the Department of Defense Era of Hope Program and the National Science Foundation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1001.

Crystallization Behavior of a New Transparent Glass-Ceramics

In this article we present a new kind of large grain transparent glass-ceramics obtained by the method of crystal growth from a homogenous glass, the simultaneous variation of the glass matrix and crystalline compositions during the crystallization results in the high transparency of this kind of large grain, high crystalline volume glass-ceramics, which have suitable refractive indexes between respective phases. The nucleation and crystallization behaviors of this kind of glass-ceramics have been investigated. The optimum heat treatment schedule for the glass was determined by means of DSC, XRD and SEM. The desirable optical property, such as laser characteristics etc, of this new kind of glass-ceramics can be further developed by doping with transition metals or rare-earths.

Cold subduction and the formation of lawsonite eclogite – constraints from prograde evolution of eclogitized pillow lava from Corsica

AbstractA new discovery of lawsonite eclogite is presented from the Lancône glaucophanites within the Schistes Lustrés nappe at Défilé du Lancône in Alpine Corsica. The fine‐grained eclogitized pillow lava and inter‐pillow matrix are extremely fresh, showing very little evidence of retrograde alteration. Peak assemblages in both the massive pillows and weakly foliated inter‐pillow matrix consist of zoned idiomorphic Mg‐poor (&lt;0.8 wt% MgO) garnet + omphacite + lawsonite + chlorite + titanite. A local overprint by the lower grade assemblage glaucophane + albite with partial resorption of omphacite and garnet is locally observed. Garnet porphyroblasts in the massive pillows are Mn rich, and show a regular prograde growth‐type zoning with a Mn‐rich core. In the inter‐pillow matrix garnet is less manganiferous, and shows a mutual variation in Ca and Fe with Fe enrichment toward the rim. Some garnet from this rock type shows complex zoning patterns indicating a coalescence of several smaller crystallites. Matrix omphacite in both rock types is zoned with a rimward increase in XJd, locally with cores of relict augite. Numerous inclusions of clinopyroxene, lawsonite, chlorite and titanite are encapsulated within garnet in both rock types, and albite, quartz and hornblende are also found included in garnet from the inter‐pillow matrix. Inclusions of clinopyroxene commonly have augitic cores and omphacitic rims. The inter‐pillow matrix contains cross‐cutting omphacite‐rich veinlets with zoned omphacite, Si‐rich phengite (Si = 3.54 apfu), ferroglaucophane, actinolite and hematite. These veinlets are seen fracturing idiomorphic garnet, apparently without any secondary effects. Pseudosections of matrix compositions for the massive pillows, the inter‐pillow matrix and the cross‐cutting veinlets indicate similar P–T conditions with maximum pressures of 1.9–2.6 GPa at temperatures of 335–420 °C. The inclusion suite found in garnet from the inter‐pillow matrix apparently formed at pressures below 0.6–0.7 GPa. Retrogression during initial decompression of the studied rocks is only very local. Late veinlets of albite + glaucophane, without breakdown of lawsonite, indicate that the rocks remained in a cold environment during exhumation, resulting in a hairpin‐shaped P–T path.

Influence of CuO and B2O3 on sintering and dielectric properties of tungsten bronze type microwave ceramics: a case study in Ba4Nd9.3Ti18O54

The effect of CuO and B2O3 co-doping on the sintering behavior, microstructure and microwave dielectric properties of tungsten bronze type Ba4Nd9.3Ti18O54 (BNT) ceramics has been investigated by means of a traditional solid-state mixed oxide route. On the one hand, it was indicated that the mixture of CuO and B2O3 is an effective sintering aid for BNT matrix compositions owing to the existence of a low-temperature eutectic reaction. On the other hand, it was found that the addition of CuO and B2O3 has an obvious effect on microwave dielectric properties of BNT ceramics, depending on the amount of sintering aids, the sample density and microstructure. The liquid phases from sintering aids can promote densification, but simultaneously induce grain growth which tends to decrease the sintering driving force. BNT ceramics doped with 3 wt% CuO–B2O3 mixture can be well sintered at 950°C for 4 h and still exhibit relatively good microwave dielectric properties.

Matrix and whole-rock fractionations in the Acfer 094 type 3.0 ungrouped carbonaceous chondrite

Abstract– We used the electron microprobe to study matrix in the ungrouped type 3.0 carbonaceous chondrite Acfer 094 using 7 × 7-point, focused-beam arrays; data points attributable to mineral clasts were discarded. The grid areas show resolvable differences in composition, but differences are less pronounced than we observed in studies of CR2 LaPaz Icefield (LAP) 02342 (Wasson and Rubin [2009]) and CO3.0 Allan Hills A77307 (Brearley [1993]). A key question is why Acfer shows an anomalously uniform composition of matrix compared with these other carbonaceous chondrites. Both whole-rock and matrix samples of Acfer 094 show enhancements of Ca and K; it appears that these reflect contamination during hot desert weathering. By contrast, the whole-rock abundance of Na is low. Although weathering effects are responsible for some fractionations, it appears that nebular effects are also resolvable in matrix compositions in Acfer 094. As with LAP 02342, we infer that the observed differences among different areas were inherited from the solar nebula and may have been carried by porous chondrules that experienced low (about 20%) degrees of melting. Acfer 094 has been comminuted by one or more impact events that may also have caused volatile loss. Thus, despite preserving evidence (e.g., an exceptionally high content of presolar SiC) implying a high degree of pristinity, Acfer 094 is far from pristine in other respects. This evidence of comminution and an O-isotopic composition similar to values measured in metamorphosed CM chondrites suggest that Acfer was hydrated before being outgassed by the inferred impact event. Convection within the plume associated with the impact event probably also contributed to the homogenization of the Acfer 094 matrix.

The thermodynamic analysis of GP zones in aged–supersaturated Al–Ag alloys

As the structural cause of hardening, Guinier–Preston (GP) zones in many alloys continue to attract great interest. The energy expressions for GP zones in the Al–Ag binary system, including the ε -state and the η -state ones, are established by combining the essential Gibbs energy for the matrix alloy with the interfacial energy and the strain energy. On the basis of the equilibria between GP zones and their surrounding matrix, the size, the composition and the precipitation sequence of different static GP zones are analyzed quantitatively at the defined matrix compositions and the aging temperatures. The calculated results can be used to explain the experimental results well.

Preparation of geopolymeric materials from sewage sludge slag with special emphasis to the matrix compositions

Solidification of SSS (sewage sludge slag) has been carried out by the geopolymer binder technique at 80°C steam conditions mixed with CFA (coal fly ash). Geopolymer liquor was prepared by mixing Na-disilicate solution of 1.27 S.G. (specific gravity) and 10 M NaOH solution in 3:1 proportion. Obtained monolithic materials were subjected to physical measurements such as 3-point flexural strength, bulk density and expansion-shrinkage. Subsequently, matrix as well as filler chemical compositions were analyzed by SEM-EDX. Results showed SSS is an active filler similar to CFA and maximal strength was reached by blending SSS with CFA in 1:3 proportion. P2O5 and CaO components of SSS strongly contributed to the polycondensation of the geopolymer liquor other than theoretically expected Al2O3 and SiO2 components.

Conditions of Magma Storage, Degassing and Ascent at Stromboli: New Insights into the Volcano Plumbing System with Inferences on the Eruptive Dynamics

Stromboli is known for its persistent degassing and rhythmic strombolian activity occasionally punctuated by paroxysmal eruptions. The basaltic pumice and scoria emitted during paroxysms and strombolian activity, respectively, differ in their textures, crystal contents and glass matrix compositions, which testify to distinct conditions of crystallization, degassing and magma ascent. We present here an extensive dataset on major elements and volatiles (CO2, H2O, S and Cl) in olivine-hosted melt inclusions and embayments from pyroclasts emplaced during explosive eruptions of variable magnitude. Magma saturation pressures were assessed from the dissolved amounts of H2 Oa nd CO2 taking into account the melt composition evolution. Both pressures and melt inclusion compositions indicate that (1) Ca-basaltic melts entrapped in high-Mg olivines (Fo89^90) generate Stromboli basalts through crystal fractionation, and (2) the Stromboli plumbing system can be imaged as a succession of magma ponding zones connected by dikes. The 7^10 km interval, where magmas are stored and differentiate, is periodically recharged by new magma batches, possibly ranging from Ca-basalts to basalts, with a CO2-rich gas phase.These deep recharges promote the formation of bubbly basalt blobs, which are able to intrude the shallow plumbing system (2^4 km), where CO2 gas fluxing enhances H2O loss, crystallization and generation of crystal-rich, dense, degassed magma. Chlorine partitioning into the H2O^CO2-bearing gas phase accounts for its efficient degassing (� 69%) under the open-system conditions of strombolian activity. Paroxysms, however, are generated through predominantly closed-system ascent of basaltic magma batches from the deep storage zone. In this situation crystallization is negligible and sulfur exsolution starts at � 170 MPa. Chlorine remains dissolved in the melt until lower pressures, only 16% being lost upon eruption. Finally, we propose a continuum in explosive eruption energy, from strombolian activity to large paroxysmal events, ultimately controlled by variable pressurization of the deep feeding system associated with magma and gas recharges.

A fast assay of water hardness ions based on alkaline earth metal induced coacervation (HALC)

In this work, a rapid assay of water hardness is presented based on the formation of a coacervate phase made up of multilamellar vesicles and close bilayers produced upon the reaction of alkaline earth metals with a carboxylate anionic surfactant in the presence of a co-surfactant (methanol). The procedure exploits the light scattering abilities of the coacervate phase which can be logarithmically linked to total hardness as CaCO(3) equivalents via spectrophotometric detection at 350 nm. The method, abbreviated as HALC, stemming from hardness by alkaline earth metal coacervation, is straightforwardly applicable overcoming the requirement for regulation of the experimental parameters involved in the determination procedure. In total, 28 water samples with various matrix compositions and hardness contents were analyzed with satisfactory accuracy as evidenced by comparison of the results with EDTA complexometric titration. The method is free from interferences from environmentally significant metal cations and inorganic anions affording detection limits as low as 13.5 mg L(-1) CaCO(3) with the aid of a correction factor, which is determined by the non-linear absorbance properties of the solution mixture, and satisfactory reproducibility (RSD=4.21-8.08%).

Evaluation of solid-state platforms for chromium (VI) potentiometric sensor development

Different platforms based on carbon pastes and composite materials, such as epoxy resin, are used to construct chromium (VI) potentiometric sensors. The materials are modified with diphenylcarbazide as selective agent for chromium (VI) ions. Matrix compositions of each sensor are optimized on the basis of graphite and ionophore amounts. The performance characteristics of all the designed solid-state potentiometric sensors are described. The same linear response range from 1.00 × 10 −6 to 1.00 × 10 −2 mol L −1 and similar detection limits, 6.3 × 10 −7 mol L −1 for graphite-epoxy sensor and 9 × 10 −7 mol L −1 for carbon paste sensor, are obtained. However, the sensor based on graphite-epoxy materials shows better selective responses and lifetime. Both sensors exhibit high selectivity to hexavalent chromium even in presence of trivalent chromium. The sensors are successfully used in direct potentiometric determinations of hexavalent chromium and are also employed as indicator electrodes in potentiometric titrations with successful results.

Phenotypic Re-expression of Near Quiescent Chondrocytes: The Effects of Type II Collagen and Growth Factors

After extensively expanding in monolayer culture, the cultured chondrocytes become quiescent. The aim of this study was to establish the hypothesis that the phenotypic function of extensively expanded primary chondrocytes may be restored with extracellular matrix (ECM) compositions with or without growth factors. The restoring effects of these microenvironmental factors on the near quiescent passage 9 (P9) chondrocyte were investigated. The data showed that exogenous type I collagen and type II collagen at 1:1 ratio stimulate cell proliferation greatly while type II collagen alone was enough to revive most of cartilaginous functions of near quiescent P9 chondrocytes. Exogenous type II collagen by itself was more effective in restoring cell proliferation rate, elevating glycosaminoglycan (GAG) accumulation and promoting the re-expression of type II collagen mRNAs in the near quiescent chondrocytes. The supplement of P9 chondrocytes with type II collagen plus TGF-beta1 and IGF-I appeared essential for the re-expression of aggrecan and type II collagen mRNA in monolayer culture. In 3D type II collagen construct, P9 chondrocytes appeared healthy as chondrocytes and showed clear lacuna. However, in 3D type I collagen matrix, only some P9 chondrocytes exhibited lacuna. The cartilaginous microenvironments are crucial to restoring chondrocyte-phenotypic features of the quiescent or 'dedifferentiated' chondrocytes, implicating the potential of expanding a scarcity of healthy chondrocytes for cartilage repair or regeneration.

A new procedure for separating and measuring radiogenic isotopes (U, Th, Pa, Ra, Sr, Nd, Hf) in ice cores

A new method for the radiogenic isotope (U–Th–Pa–Ra, Sr, Nd, Hf) analysis of the soluble and insoluble components found within ice cores is presented. Melting experiments with rock standards in the presence of EDTA indicate that carbonates, as well as silicates, can be buffered sufficiently to preclude dissolution. The use of EDTA allows adsorbing species, such as Th and Hf, to remain in solution during melting thus fully separating the dust (insoluble) and sea salt (soluble) components of the ice after filtration. A new elemental separation scheme for low sample masses, less than 5 mg solid material, utilizes 4 primary ion exchange columns and two “clean-up” columns to fully isolate U, Th, Pa, Ra, Sr, Nd, and Hf while maintaining high yields. Elution schemes measured for USGS rock standards and a Chinese loess are presented to provide a comparison for variable matrix compositions. Mass spectrometer techniques were modified to measure small aliquots of the standards, equivalent to the amounts found in ice core samples, 10 ng and less. A MC-ICPMS was employed for the measurement of U, Th, Pa, Ra, and Hf; results of the experiments show that with ion yields up to 1%, rock standards have errors for 234U/ 238U of 1%, 230Th/ 232Th of 1.5%, [ 228Ra] of 9%, and 176Hf/ 177Hf of 100 ppm. MC-TIMS measurements of Sr and Nd show similar errors for small sample sizes: 87Sr/ 86Sr of 50 ppm and 143Nd/ 144Nd of 80 ppm. This new analytical method increases the number of possible tracers measured from a single sample, reducing separation times and sample consumption, as well as providing the addition of a radiometric clock, U-series, to the traditional suite of isotopic tracers, Sr, Nd, and Hf.

Limestone pseudoconglomerates in the Late Cambrian Gushan and Chaomidian Formations (Shandong Province, China): soft‐sediment deformation induced by storm‐wave loading

AbstractThis paper focuses on the formative processes of limestone pseudoconglomerates in the Gushan and Chaomidian Formations (Late Cambrian) of the North China Platform, Shandong Province, China. The Gushan and Chaomidian Formations consist mainly of limestone and shale (marlstone) interlayers, wackestone to packstone, grainstone and microbialite as well as numerous limestone conglomerates. Seventy‐three beds of limestone pseudoconglomerate in the Gushan and Chaomidian Formations were analysed based on clast and matrix compositions, internal fabric, sedimentary structures and bed geometry. These pseudoconglomerates are characterized by oligomictic to polymictic limestone clasts of various shapes (i.e. flat to undulatory disc, blade and sheet), marlstone and/or grainstone matrix and various internal fabrics (i.e. intact, thrusted, edgewise and disorganized), as well as transitional boundaries. Limestone pseudoconglomerates formed as a result of soft‐sediment deformation of carbonate and argillaceous interlayers at a shallow burial depth. Differential early cementation of carbonate and argillaceous sediments provided the requisite conditions for the formation of pseudoconglomerates. Initial deformation (i.e. burial fragmentation, liquefaction and injection) and subsequent mobilization and disruption of fragmented clasts are two important processes for the formation of pseudoconglomerates. Burial fragmentation resulted from mechanical rupture of cohesive carbonate mud, whereas subsequent mobilization of fragmented clasts was due to the injection of fluid materials (liquefied carbonate sand and water‐saturated argillaceous mud) under increased stress. Storm‐wave loading was the most probable deformation mechanism, as an external triggering force. Subsequent re‐orientation and rounding of clasts were probably prolonged under normal compactional stress. Eventually, disrupted clasts, along with matrix materials, were transformed into pseudoconglomerates by progressive lithification. Soft‐sediment deformation is prevalent in alternate layers of limestone and mud(marl)stone and/or grainstone, regardless of their depositional environments.

Multi-element quantification of ancient/historic glasses by laser ablation inductively coupled plasma mass spectrometry using sum normalization calibration

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for quantitative analysis of ancient/historic glasses is subject to calibration issues which have been addressed in this work. Since ancient/historic glasses have widely ranging matrix compositions, a complementary analysis by an alternative method is generally employed to determine at least one major element which can be used as an internal standard. We demonstrate that such a complementary analysis is unnecessary using a so-called sum normalization calibration technique (mathematically formulated) by simultaneous measurement of 54 elements and normalizing them to 100% [w/w] based on their corresponding oxide concentrations. The crux of this approach is that by assuming a random internal standard concentration of a particular major oxide, e.g. SiO 2, the normalization algorithm varies the internal standard concentration until the cumulated concentrations of all 54 elemental oxides reach 100% [w/w]. The fact that 54 elements are measured simultaneously predetermines the laser ablation mode to rastering. Nine glass standards, some replicating historic compositions, were used for calibration. The linearity of the calibration graphs (forced through the origin) represented by the relative standard deviations in the slope were between 0.1 and 6.6% using SiO 2 as an internal standard. This allows high-accuracy determination of elemental oxides as confirmed by good agreement between found and reported values for major and minor elemental oxides in some synthetic glasses with typical medieval composition (European Science Foundation 151 and 158). Also for trace elemental concentrations of lanthanides in a reference glass (P&H Developments Ltd. DLH7, a base glass composition with nominally 75 μg g −1 elements added) accurate data were obtained. Interferences from polyatomic species and doubly charged species on the masses of trace elements are possible, depending on the base composition of the glass, with Ba and Sb glasses showing potential interferences on some lanthanides. We showed that they may be reduced to a great extent by using an Octopole Reaction System although the overall sensitivity decreases which may be a problem for some low-level determinations.

Application of the Monkman–Grant law to the creep fracture of nodular cast irons with various matrix compositions and structures

Creep behaviour of nodular cast irons with three different matrix compositions and microstructures has been investigated up to fracture in the elastic regime for temperatures between 650 °C and 900 °C. The elastic stress levels were chosen taking into account the non-linear dependence between elastic stresses and corresponding strains. Results show that austenitic cast irons are more creep resistant than ferritic ones. However, all materials obey to a single Monkman–Grant law. Fracture of samples with short life times is dominated by the plastic straining of the matrix independently of their metallurgical state. Creep fracture of long life time samples is controlled by diffusion mechanisms like cavity nucleation on the grain boundaries. It is shown that the damage growth in secondary and tertiary creep regimes can be represented by a single parameter whatever the creep mechanisms and the metallurgical properties of nodular cast irons.

Effect of alloying additions on the structure and mechanical properties of Fe3Al -1C intermetallic alloy

Effect of titanium and nickel on the structure and properties of Fe3Al intermetallic alloy containing about 1.0wt.% C have been investigated. The composition of the alloying element was substituted for Iron. The alloys were prepared by melting commercial grade raw materials iron, aluminum, titanium or nickel in air induction furnace with flux cover (AIMFC). Further these ingots were refined by electroslag refining (ESR) process. These ingots could be successfully hot-worked using conventional hot-forging and hot-rolling techniques. The hot-worked material was sound and free from cracks. ESR hot-rolled alloys were examined using optical microscopy, X-ray diffraction (XRD), scanning electron micrograph (SEM) to understand the microstructure of these alloys. The electron probe micro analysis (EPMA) studies were carried out to determine the matrix and precipitate compositions and to identify the phases present in the alloys. The base alloy and the alloy containing Ni exhibited a two-phase microstructure of Fe3AlC0.5 precipitates in Fe3Al matrix. The alloy containing Ti exhibits three-phase microstructure, the additional phase being TiC precipitate. Ti addition resulted in no improvement in strength at room temperature and at 873 K whereas Ni addition has resulted in greater improvement in strength at room temperature and at 873 K and also improved the creep life significantly from 66 hrs to 111 hrs.

Determination of hydrogen content in geological samples using elastic recoil detection analysis (ERDA)

The present study illustrates the interest of using the elastic recoil detection analysis (ERDA) method to characterize any geological sample matrix with respect to hydrogen. ERDA is combined with Rutherford back scattering (RBS) and particle induced X-ray emission (PIXE), allowing the simultaneous characterization of the matrix with respect to major and trace elements ( Z > 15). Analyses are performed by mapping of a 4 × 16 μm 2 incident beam of 4He + on large areas (50 × 200 μm 2). The method is almost not destructive and requires no calibration with respect to well known hydrous samples. Hydrous and nominally anhydrous phases in contact with each other in the same sample may both be characterized. The depth of the analyses is limited to several μm beneath the surface, allowing tiny samples to be investigated, provided their sizes are larger than the incident beam. Our setup has been improved in order to allow H determination on a micrometric scale with a 5–15% relative uncertainty and a detection limit of 94 wt ppm H 2O. We present multi-elemental mappings on a large panel of samples: (1) natural and analogue synthetic glasses from Stromboli volcano (0.44–4.59 wt% H 2O), natural rhyolitic glasses (1466–1616 wt ppm H 2O); (2) magmatic rhyolitic melt inclusions from Guadeloupe Island (4.37–5.47 wt% H 2O) and their quartz host crystal (2020 ± 230 wt ppm H 2O); (3) nominally anhydrous natural (82–260 wt ppm H 2O) and experimentally hydrated (240–790 wt ppm H 2O) olivines; natural clinopyroxenes (159–716 wt ppm H 2O); natural orthopyroxenes (201–452 wt ppm H 2O); a natural garnet (90 wt ppm H 2O). Results show that ERDA is a strong and accurate reference method that can be used to characterize geological sample from various matrix compositions from high to low water contents. It can be used to calibrate other methods of microanalysis such as Fourier Transform Infrared Spectroscopy (FTIR) or secondary ion mass spectrometry (SIMS).