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Foam composite panels made from hybrid fillers are materials developed to have low density with high mechanical properties. This work focuses on improving the mechanical properties of epoxy-based foam composite panels with hybridized fillers by combining hollow glass microspheres (HGM) and nanoclay. The HGM content was varied from 1 wt.% to 3 wt.% in foam composites panel, while nanoclay content was varied from 1 wt.% to 5 wt.% in each of the HGM-filled series of foam composites panel, these foam composite panels were fabricated using a conventional resin casting method. The mechanical properties such as tensile strength, impact strength, hardness, flexural strength of the prepared hybrid-filled foam composite panels were determined and compared with the neat epoxy. It was found that the hybrid-filled foam composite panels exhibited improved mechanical properties than the neat epoxy. These improved properties were because of excellent interfacial adhesion between the hybrid fillers and the matrix. The improved mechanical properties could suggest that this material may be suitable for application in industries where lightweight materials with good mechanical properties are required. This study showed a new area of synthetic foam development research by enhancing mechanical properties using hybrid-filled. KEYWORDS fillers, foam composite panels, hollow glass microspheres, mechanical properties, Nanoclay, 1 | INTRODUCTION Epoxy-based foam composites are lightweight materials with attractive mechanical properties, hollow structures, very good adhesion, good chemical properties, heat resistance, low shrinkage, corrosion resistance, and excellent electrical [...]

In this article, the 3D printed polyamide12/carbon nanotube (PA12/CNT) nanocomposites were joined using laser welding. The factorial design method was applied to study the effect of laser power, welding velocity, and CNT content on the tensile and impact strengths of welded samples. The differential scanning calorimetry and thermogravimetric analysis were also used to measure the thermal stability and weight loss temperature of the nanocomposite. The results indicated that the increase of CNTs enhanced the thermal stability of the nanocomposite and so increased its melting point and crystallinity percentage. The impact and tensile strengths of the weld enhanced when laser power elevated from 40 to 50 W, but elevation of laser power up to 60 W decreased the impact and tensile strengths due to thermal degradation of the nanocomposite. A rise in welding velocity from 10 to 20 mm/s enhanced the tensile strength, while the impact strength initially enhanced and then decreased. The highest tensile strength obtained at 2 wt% CNT, whereas the addition of CNTs up to 4 wt% led to their agglomeration, which resulted in the reduction of impact and tensile strengths. Finally, the optimal conditions for concurrent increase of impact and tensile strengths include the laser power of 51 W, welding velocity of 12.5 mm/s, and CNT content of 2.3 wt%. KEYWORDS fused filament fabrication, laser welding, mechanical properties, PA12/CNT nanocomposite, thermal properties, 1 | INTRODUCTION Polymer composites have different applications in automotive, airplane, electronic, and packaging industries for enhancing the manufacturing efficiency and reducing the cost of the products. [1-3] In recent [...]

Additive manufacturing (AM) provides a tremendous opportunity to synergistically couple materials, design, and manufacturing strategies. One can strive toward fabricating parts with targeted properties by enabling site-specific metal-metal or metal-ceramic [...]

This study presents the experimental investigation of the effect of curing conditions on the properties of mortar mixtures made with sodium carbonate activated slag-glass powder as a binder. Slag and glass powder were used at an equal percentage as the aluminosilicate precursor and the binary blend was activated with sodium carbonate. The corresponding compressive strength and ultrasonic pulse velocity of the mixtures cured in different conditions were investigated. The curing conditions used in this study are dry, moist, and submerged curing. Microstructural investigations were also carried out to understand the microstructural properties of the mixtures exposed to these curing conditions. Results from this study showed that moist curing is the most effective curing method for mortar made with sodium carbonate alkali-activated slag-glass powder as a binder. Microstructural evaluations further confirm the strength results as mortar samples cured in a moist condition exhibited a denser microstructure. Key words: alkali-activated binder, slag, glass powder, compressive strength, ultrasonic pulse velocity, microstructural analysis. Cette etude presente la verification experimentale de l'effet des conditions de durcissement sur les proprietes des melanges de mortier faits avec du laitier-poudre de verre a activation au carbonate de sodium comme liant. Le laitier et la poudre de verre ont ete utilises a un pourcentage egal comme precurseur de l'aluminosilicate et le melange binaire a ete active a l'aide de carbonate de sodium. La resistance a la compression et la vitesse d'impulsion ultrasonique correspondantes des melanges durcis dans differentes conditions ont ete etudiees. Les conditions de durcissement aux fins de cette etude sont seches, humides et immergees. Des etudes microstructurales ont egalement ete effectuees pour comprendre les proprietes microstructurales des melanges soumis a ces conditions de durcissement. Les resultats de cette etude ont montre que le durcissement humide est la methode de durcissement la plus efficace pour le mortier fait avec du laitier-poudre de verre a activation au carbonate de sodium comme liant. Les evaluations microstructurales confirment davantage les resultats de la resistance, car les echantillons de mortier durcis en condition humide presentaient une microstructure plus dense. [Traduit par la Redaction] Mots-cles : liant a activation alcaline, laitier, poudre de verre, resistance a la compression, vitesse d'impulsion ultrasonique, analyse microstructurale., Introduction The increasing demand and utilization of portland cement (PC) as a binder for different construction applications has posed an environmental threat in the construction industry. This environmental threat with [...]

The mechanical behaviors of five polyether block amide foams, obtained by mold-opening foam injection process, were investigated with regard to their microstructures. The materials vary in mass ratios of hard versus soft segments, and/or in process packing time. The resulting microstructures have been characterized in terms of cavity size and shape ratios, by analyzing scanning electron microscope images after careful sample preparation. The foam mechanical responses have been characterized in compression at small and large strain. At small strain, the initial linear part of the stress-strain curve is enhanced firstly by the hard segment mass ratio and secondly by the fineness of the microstructure. Similar results have been obtained at large strain. The foam viscoelasticity at large strain has been characterized by stress relaxation and strain recovery tests, relevant for foam applications. Reduced packing time and pressure have been shown to lead to the presence of undesired large cavities. The morphological defects appear to have a negligible impact on the macroscopic mechanical behavior of the foams at infinitesimal strain, but lead to critical inconsistency at large strain. Furthermore, the mechanical behavior of the tested polyether block amide foams is controlled first by hard versus soft segments ratio, and second by the microstructure fineness. KEYWORDS foam, mechanical behavior, microstructure, recovery, shape ratio, 1 | INTRODUCTION Cellular materials like wood, cancellous bone, honeycombs ... act as useful structures in nature. Cellular polymeric materials have been developed inspired by these natural structures. They are [...]

The influence of different shear stresses induced by changing injection molding speeds on molecular chain orientation and lamellar branching of [beta]-nucleated iPP/poly(ethylene terephthalate) (PET) microparts was investigated using two-dimensional wide-angle X-ray diffraction and 2D-small-angle X-ray scattering. Results indicated that the prevailing shear stress can promote the formation of parent-daughter [alpha]-crystal structure and twisted shish-kebab structure in subsequent microparts. The diffraction of (300) plane of [beta]-crystals was also observed at varying injection speeds. Increasing injection speeds can significantly enhance the content of [beta]-crystals from 24 to 41% for [beta]-nucleated iPP microparts. Additionally, the content of [beta]-crystals was further enhanced in P-nucleated iPP/PET microparts with in situ formation of PET microfibrils under intensive shearing conditions. The addition of both PET and P-nucleation agents coupling with high shearing conditions exerts a synergetic effect on the development of [beta]-crystals. However, the orientation degree of crystal lattice decreased with increasing injection speeds for both [beta]-nucleated iPP and iPP/PET microparts. KEYWORDS crystallization, microinjection molding, microstructure, polypropylene, 1 | INTRODUCTION Recently, the development of miniature devices has attracted attention as more and more functions are being integrated into small systems. [1-3] Also, microinjection molding (MIM) has become [...]

Canistel seeds are part of the residues of Canistel fruit which can be used as functional foods, such as flour to be processed into various foods. This research was aimed at determining the physicochemical properties of canistel seed flour. Canistel seed was made into flour with two treatments; they were Blanched Canistel Seed Flour (BCSF) (at 80[degrees]C for 10 minutes) and Unblanched Canistel Seed Flour (UCSF). The flour process involves sorting, washing, treatment, stripping the shell and epidermis, washing again, drying, flaking and sieving. Physical analysis carried out included yield (by difference method), white degree of spectrophotometric reflectance method (Chromatometer), starch gelatinization profile using Rapid Visco Analyzer (RVA), the morphology of starch granules using polarization microscopy and Scanning Electron Microscope (SEM). Chemical analysis conducted on the BCSF and UCSF samples included proximate, amylose, amylopectin and starch content. Blanching at 80[degrees]C for 10 minutes had a significant effect on the physical properties of Canistel seed flour; yields were higher (41.6%) and chromatometric (colour) levels were lower (80.61). Pasting properties profile showed that UCSF had higher peak viscosity, breakdown viscosity but lower setback viscosity compared with the BCSF. Scanning Electron Microscope (SEM) and polarized light microscope showed starch granule structure changed due to the blanching. The appearance of starch granules on UCSF shows a tight starch granule. The appearance of starch granules on BCSF shows blanching treatment has changed the shape of the starch granules to be broken or damaged. The unblanched canistel seed flour (UCSF) showed that the starch granule still had birefringence appearance. This shows that the granule structures of the UCSF remained undamaged. Observation of the morphology of starch granules using polarization microscopy on BCSF showed the starch granule was not visible and there was no appearance of birefringence. The loss of birefringence indicates that the starch granules had been damaged due to heating or hydrolysis. Chemical analyses on the samples showed significantly higher amylose content (24.79) but lower amylopectin content (31.39) in BCSF than UCSF. Starch, fat and carbohydrates contents were not significantly different (p>0.05) between BCSF and UCSF. Ash and protein content were significantly higher (p>0.05) in UCSF compared to the BCSF. Blanching of canistel seed flour reduces the swelling power of starch granules, increases retrogradation, accelerates thickening, decreases nutrition content, and changes microstructure of Canistel seed flour. Key words: Blanching, canistel seed flour, physicochemical characteristics, starch granule morphology, proximate, INTRODUCTION Canistel fruit contains nutrients such as fiber, starch, calcium, phosphorus, carotene, thiamine, riboflavin, niacin and vitamin C. The flesh can be frozen or dried and made into flour [1]. [...]

The cooling of polypropylene melts and their solidification is analyzed taking into account the mutual dependency of crystallization and heat transfer. A single equation for the crystallinity is used. This equation also provides information for the ensuing microstructure. No restrictive assumption is necessary when nucleation kinematics and growth rates are known. Crystallization itself has a strong influence on heat transfer and cooling time during processing because all material parameters depend on crystallinity. The theoretical results obtained with these parameters compare favorably with the temperature drop and the increase of crystallinity observed during cooling experiments. The potential of a simple method for evaluating the spherulitic structure at the end of crystallization is demonstrated by comparing the calculated and the measured size distribution of spherulites in a solidified slab. The combined computation of heat transfer and crystallization presented in this study is important for calculating the cooling time of plastics processing operations., INTRODUCTION Semicrystalline polymers such as polypropylene are used by the plastics processing industry as basic materials for numerous products. In general, the processing steps are melting, shaping or molding, and [...]

Freeze-thaw action is considered to be one of the most destructive actions that can induce significant damage in stabilized subgrades in seasonally frozen loess areas. Laboratory tests including frost heave--thaw shrinkage and microstructure change during freeze-thaw cycles were conducted to evaluate the volume change rate of loess stabilized with cement, lime, and fly ash under the impact of cyclic freeze-thaw conditions. The loess specimens collapsed after eight freeze-thaw cycles (192 h), but most stabilized loess specimens had no visible damage after all freeze-thaw cycles were completed. All of the stabilized loess samples underwent a much smaller volume change than the loess alone after the freeze-thaw cycles. Although surface porosity and equivalent diameter of stabilized loess samples increased, the stabilized loess can retain its microstructure during freezethaw cycles when the cement content was less than 6%. To ensure freeze-thaw resistance of stabilized loess subgrades, the mix proportions of the three additives was recommended to be 4 to 5% cement, 6% lime, and 10% fly ash. Key words: stabilized loess, freeze-thaw cycle, frost heaving, thaw shrinkage, microstructure, cement, lime, fly ash. On considere l'action du gel et du degel comme etant une des actions les plus destructives pouvant causer des dommages importants des sols de fondation stabilises dans les zones de loess ayant subi un gel saisonnier. Les essais en laboratoire comprennent le soulevement par le gel et le retrait du au degel alors qu'on a mene des changements de microstructure au cours des cycles de gel-degel afin d'evaluer le taux de changement du volume du loess stabilise au moyen du ciment, de la chaux et de la cendre volante sous l'effet des conditions de gel-degel. Les specimens de loess se sont effondres apres huit cycles de gel-degel (192 h), mais la plupart des specimens de loess stabilise n'avaient aucun dommage visible apres que tous les cycles de gel-degel furent completes. Tous les echantillons de loess stabilise ont subi un changement de volume bien moindre que le loess seul apres les cycles de gel-degel. Bien que la porosite de surface et le diametre equivalent des echantillons de loess stabilise aient augmente, le loess stabilise peut garder sa microstructure pendant les cycles de gel-degel lorsque le contenu en ciment etait moins de 6 %. Afin d'assurer la resistance au gel-degel des sols de fondation de loess, on a recommande que les proportions des melanges des trois adjuvants soient de 4 a 5 % ciment, de 6 % chaux et de 10 % de cendre volante. [Traduit par la Redaction] Mots-cles: loess stabilize, cycle de gel-degel, soulevement par le gel, retrait du au degel, microstructure, ciment, chaux, cendre volante., Introduction Loess is a collapsible soil covering approximately 10% of the Earth's surface, it appears in vast areas from Western Europe to China (Qian et al. 1985), across North America, [...]

This article studied the demolding of an array of injection molded micro-structures based on a design of experiments (DOE) method. The demolding force ([F.sub.d]) to eject an array of 4 x 5 micro-ridges from the cavity of a mold was calculated indirectly. It was found that mold temperature had a significant effect on the demolding force: the demolding force decreased as mold temperature increased and as the part substrate thickness also increased. The demolding force is a combination of the adhesion force and friction force that exist between a molded feature and the micro-cavities of a mold. When the processing parameters were optimized to minimize the demolding force during the ejection process, it was found that the adhesion force had a bigger influence than the friction force. POLYM. ENG. SCI., 56:810-816, 2016. © 2016 Society of Plastics Engineers, INTRODUCTION Microfluidic technologies have found many applications in fields such as medical diagnostics, biotechnology and microchemistry [1], Many of the devices used in these fields contain various micro-sized features which [...]

The collapse potential, mineralogy, microstructure, and particle morphology of a loess from the Loess Plateau, China, were characterized by double oedometer testing, X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and image analysis to elucidate the origin of its collapse behavior. Results show that the loess is highly collapsible with a maximum collapse index of 6.7% at a vertical stress of ~200 kPa. The deposit contains both nonclay (i.e., quartz, albite, muscovite, and calcite) and clay (i.e., two chlorites) minerals. Microstructural, chemical, and image analyses indicate that interparticle calcite and clay cementation and silt particle morphology render the intact soil a metastable structure. Wetting-induced collapse is attributed to both primary and secondary microstructure features. The former is the abundance of weakly cemented, unsaturated, porous pure clay and clay-silt mixture aggregates whose slaking upon wetting initiates the overall structural collapse, while the latter consists of high porosity, unstable particle contacts, and clay coating on silt particles that act synergistically to augment the collapse. A conceptual microstructural model of a four-tiered hierarchy (i.e., primary clay and silt particles, clay aggregates and clay-coated silt particles, clay-silt mixture aggregates, and cemented aggregate matrix) is proposed to represent its structural characteristics and to account for its high collapsibility. Key words: collapsibility, loess, microstructure, mineralogy, particle morphology, silt. Le potentiel d'affaissement, la structure mineralogique, la microstructure et la morphologie particulaire d'un loess provenant du Plateau de Loess, en Chine, ont ete caracterises a l'aide d'essais a l'oedometre double, par diffraction des rayons X, au moyen de la microscopie electronique a balayage associee a la spectroscopie a rayons X a dispersion d'energie et par analyse d'images, afin de connaitre l'origine de l'affaissement du loess etudie. Les resultats obtenus montrent que ce dernier est fortement susceptible de s'affaisser, son indice maximal d'affaissement etant egal a 6,7 % pour une contrainte verticale d'environ 200 kPa. Le depot de loess contient a la fois des mineraux non argileux (c.-a-d. du quartz, de l'albite, de la muscovite et de la calcite) et argileux (c.-a-d. deux chlorites). Des analyses microstructurales, chimiques et d'images montrent que la cimentation interparticulaire de la calcite et de l'argile et la morphologie des particules de limon transforment le sol intact en structure metastable. L'affaissement du a l'humification s'explique par les caracteristiques des microstructures primaires et secondaires. La microstructure primaire est caracterisee par l'abondance d'agregats faiblement cimentes, non satures et poreux d'argile pure et de limon argileux dont le ramollissement du a l'humidification amorce l'affaissement structural, alors que la microstructure secondaire consiste en des particules de limon instable et fortement poreux en contact les unes avec les autres et en une couche d'argile recouvrant ces dernieres, l'ensemble contribuant a accentuer le phenomene d'affaissement. Un modele microstructural conceptuel a quatre niveaux (soit les particules primaires d'argile et de limon, les agregats d'argile et les particules de limon recouvertes d'argile, les agregats de limon argileux et la matrice formee par les agregats cimentes) est propose pour illustrer les caracteristiques structurales du loess etudie et pour expliquer sa forte tendance a s'affaisser. [Traduit par la Redaction] Mots-cles: tendance a l'affaissement, loess, microstructure, mineralogie, morphologie particulaire, limon., Introduction Loess, an aeolian, nonstratified deposit, is composed of primarily silt-sized particles with small fractions of clay and sand particles. It occurs widely around the world, including Asia, Africa, central [...]

During conventional cone penetration testing in silt, the soil will normally be partially drained. If the penetration rate varies, time for drainage is altered and therefore the measured cone resistance and pore pressure will change. This paper studies the change in soil microstructure around the probe during cone penetration carried out at different penetration rates to investigate the failure mechanism and the processes controlling drainage in silt. Backscattered electron images of polished thin sections prepared from frozen samples at the end of penetration were used. Making use of advanced image-processing techniques, the statistical distribution of particle orientations and the local porosity were investigated for zones around the cone tip and shaft. The spatial distribution of the measured microscale parameters in the region near the probe indicates that the soil deformation during a piezometric cone penetration test (CPTU) in silt leads to the formation of both contractive and dilative zones. The macro response of the material, presented by the pore pressure and cone penetration resistance measured during the test, results from the competition between these zones during penetration, which is shown to be dependent on the penetration rate. Key words: silts, site investigation, fabric-structure of soils, microscopy, cone penetration test. Durant un essai au penetrometre statique dans du limon, le sol est en principe partiellement draine. Si la vitesse de penetration varie, le temps de drainage et donc la resistance du cone et la pression interstitielle varient egalement. Le present article s'interesse aux variations de la microstructure du sol autour de la sonde durant la penetration du cone dans le sol pour differentes vitesses de penetration, avec l'objectif d'etudier le mecanisme de rupture et les processus qui influent sur le drainage de l'eau dans le limon. Dans le cadre de la presente etude, on a utilise des images, obtenues a l'aide d'un microanalyseur a faisceau electronique, de fines sections d'echantillons de limon congeles preparees apres penetration du cone. A l'aide de techniques avancees de traitement d'image, la distribution statistique de l'orientation des particules et la porosite locale dans les zones avoisinant la pointe du cone et la tige du penetrometre ont ete analysees. La distribution spatiale des parametres mesures a l'echelle microscopique a proximite de la sonde montre que la deformation du sol durant l'essai au penetrometre statique (CPTU) realise sur le limon entraine la formation de zones de contraction et de dilatation. La reponse macroscopique du materiau, representee par la pression interstitielle et par la resistance a la penetration du cone, toutes deux mesurees durant les essais, est causee par la competition entre ces zones lors de la penetration, competition qui semble dependre de la vitesse de penetration. [Traduit par la Redaction] Mots-cles: limon, etude sur le terrain, structure et microstructure des sols, microscopie, essai au penetrometre statique., Introduction A cone penetration test (CPT) consists of pushing a cone tip at the end of a cylindrical probe of 35.7 mm diameter (standard size) into the ground at a [...]

Although matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis is an important tool for analyzing and characterizing biomolecules of varying complexity, the sensitivity of MALDITOFMS is dependent on proper preparation of the sample, a process that is oftentimes problematic and requires considerable expertise. In this study, we have developed a radiate microstructure chip on which samples can be concentrated for analysis by MALDI-TOFMS. The sample/ matrix mixture was deposited onto the central space of the well on the chip and allowed to dry. Microscopic analysis confirmed that the applied samples were confined to the central zone. Sample spots focused on the chip were much smaller than those on an unmodified plate with the same total volume. Optimizing processes of several preparation factors were also performed to ensure matrix homogeneity in our chip. Analysis of the samples with MALDI-TOFMS showed that the signals from samples on our chip were significantly greater than those on the unmodified plate. The feasibility of using this chip to detect peptides and phosphopeptides was also demonstrated. 10.1021/ac101426n

The perforant path (PP) undergoes synaptic changes in the course of aging and dementia. Previous studies attempting to assess the integrity of the PP in humans using diffusion tensor imaging (DTI) were limited by low resolution and the inability to identify PP fibers specifically. Here we present an application of DTI at ultrahigh submillimeter resolution that has allowed us to successfully identify diffusion signals unique to the PP and compare the intensity of these signals in a sample of young adults and older adults. We report direct evidence of age-related PP degradation in humans in vivo. We find no evidence of such loss in a control pathway, the alveus, suggesting that these findings are not evidence for a global decline. We also find no evidence for specific entorhinal gray matter atrophy. The extent of PP degradation correlated with performance on a word-list learning task sensitive to hippocampal deficits. We also show evidence for gray matter diffusion signals consistent with pyramidal dendrite orientation in the hippocampus and cerebral cortex. Ultrahigh-resolution microstructural DTI is a unique biomarker that can be used in combination with traditional structural and functional neuroimaging methods to enhance detection of AIzheimer disease in its earliest stages, test the effectiveness of new therapies, and monitor disease progression. aging | hippocampus | DTI | entorhinal | dentate doi/10.1073/pnas.1002113107

The strong dependence of separation behavior on ultrathin-layer chromatography (UTLC) stationary phase microstructure motivates continued UTLC plate design optimization efforts. We fabricated 4.6-5.3 [micro]m thick normal phase silica UTLC stationary phases with several types of in-plane macropore anisotropies using the glancing angle deposition (GLAD) approach to engineering nanostructured thin films. The separation behaviors of two new media, isotropic vertical posts and anisotropic bladelike films, were compared to that of anisotropic chevron media. Channel-like structures within the anisetropic media introduced preferential mobile phase flow directions that could be exploited to give separation tracks diagonal to the development direction. Extraction of chromatograms from these angled tracks required the development of a now analytical approach that involved a commercial flatbed film scanner and custom numerical image analysis software. GLAD stationary phase performance was quantified using the Dimethyl Yellow dye separated from a lipophilic dye mixture over migration distances leas than ~10 mm. The limits of detection were 10 [+ or -] 4 ng for the vertical pests and 11 [+ or -] 3 ng for the bladelike media. We obtained theoretical plate heights that varied with film microstructure between 12 and 28 [micro]m. Unoptimized separation performance was comparable to that of other planar chromatography media. Macropore anisotropies engineered by GLAD may expand the capabilities of future UTLC stationary phases. 10.1021/ac101004b

The transformation of magnetite to hematite is described and analyzed in three natural samples of banded iron formation, from Quadrilatero Ferrifero, Brazil. In each sample, a particular microstructure related to the transformation process is described. In the first, magnetite crystals are large and euhedral, and they display the beginning of the transformation into hematite. In the second sample, a relict crystal of magnetite was found and the fabric of the transformed hematite was evaluated. In the last sample, the foliation was the main observed structure and the correlations of magnetite and hematite lattices were measured. All the microstructures were analyzed in a scanning electron microscope equipped with a detector for electron backscatter diffraction allowing the complete analysis of crystallographic orientations of hematite and magnetite on a local scale. The results show that the orientations of the basal planes of hematite coincide with the orientations of the octahedral planes of magnetite, indicating that the hematite crystals are a direct product from the magnetite transformation. Keyword: Magnetite, hematite, mineral transformation, electron backscatter diffraction (EBSD), banded iron formation (BIF) DOI: 10.2138/am.2010.3201

In this paper, the effects of carbonation on pore structure of blended pozzolan cement pastes were investigated. Ordinary Portland cement (OPC) was partially replaced with ground palm oil fuel ash (POA), ground rice husk ash (RHA) and classified fine fly ash (FA). The strength, total porosity, specific surface area, and pore size distribution were tested. In general, incorporation of pozzolans increased the total porosity of blended cement pastes in comparison to that of OPC paste. Carbonation of pastes under 5% C[O.sub.2] and 50% relative humidity (RH) for 28 days resulted in filling of the pore voids and possible attack on calcium silicate hydrate (CSH) depending on the type of pozzolan used. After carbonation, total porosity decreased and specific surface areas of the blended pozzolan cement pastes reduced indicating the infilling of voids. Pore size distributions of POA and RHA pastes were different to those of FA pastes. Large pores of the POA and RHA pastes were increased indicating coarsening of pores owing to possible attack on CSH. It is possible that POA and RHA were highly reactive and hence their uses resulting in severe carbonation compared to use of FA. DOI: 10.1061/(ASCE)0899-1561(2009)21:11(666) CE Database subject headings: Fly ash: Microstructures; Cement; Portland cement: Carbonation.

The build up of scale inside autoclaves during high-pressure acid leaching of nickel laterite ore currently represents a significant industrial problem in processing plants. In this study, the crystallographic microstructure of natrojarosite scale developed on stirring rods inside a high-pressure acid leach autoclave are investigated using electron backscatter diffraction (EBSD). Backscatter electron imaging shows compositional layering of natrojarosite with dispersed minor iron oxide crystals and regularly spaced, parallel layer micro-porosity. Analysis of the scale by EBSD reveals that natrojarosite forms elongate grains with strong (000l) crystallographic preferred orientation with c axes aligned within the plane of the agitator substrate, consistent with unitaxial precipitation from a fluid. The natrojarosite grains contain a complex internal substructure of low-angle ( Keywords: Scale, microstructure, defects, mineral, growth, jarosite

The microstructure of nearly 200 common gem opal-A and opal-CT samples from worldwide localities was investigated using scanning electron microscopy (SEM). These opals do not show play-of-color, but are valued in the gem market for their intrinsic body color. Common opal-AG and opal-CT are primarily built from nanograins that average ~25 nm in diameter. Only opal-AN has a texture similar to that of glass. In opal-AG, nanograins arrange into spheres that have successive concentric layers, or in some cases, radial structures. Common opal does not diffract light because its spheres exhibit a range of sizes, are imperfectly shaped, are too large or too small, or are not well ordered. Opal-AG spheres are typically cemented by non-ordered nanograins, which likely result from late stage fluid deposition. In opal-CT, nanograins have different degrees of ordering, ranging from none (aggregation of individual nanograins), to an intermediate stage in which they form tablets or platelets, to the formation of lepispheres. When the structure is built of lepispheres, they are generally cemented by non-ordered nanograins. The degree of nanograin ordering may depend on the growth or deposition rate imposed by the properties of the gel from which opal settles, presumably, fast for non-ordered nanograin structures in opal-CT to slow for the concentric arrangement of nanograins in the spheres of opal-AG. Keywords: Opal-A, opal-CT, common opal, structure, SEM, nanograin

Quantitative microstructural analysis of zircon using electron backscatter diffraction (EBSD) requires a comparison of empirically collected electron backscatter patterns with theoretical patterns or 'match units' derived from known crystallographic parameters. There are 23 possible crystallographic data sets for zircon, and associated match units, derived from natural and synthetic zircon and from theoretical calculations over a range of pressures and different rare earth element (REE) compositions. A systematic assessment of these match units has been undertaken by EBSD analysis of each of four zircons from a range of geological environments combined with principal components analysis and self-organizing map networks. Comparison of the different match units shows a systematic relationship across all samples that are related to changes in unit-cell dimensions associated with pressure and compositional variations. Systematic variations in the data generated from 96 EBSD maps, each comprising 10 000 electron backscatter patterns, indicate that match units associated with increasing pressure or REE dopants yield poorer quality EBSD data. The match units from low-pressure, undoped, natural zircon consistently yield the best EBSD results and are recommended for natural zircon EBSD studies irrespective of the zircon source or U content. The results provide a clear strategy for optimizing the acquisition and analysis of EBSD data from zircon from both crustal and mantle sources. In addition, the developed approach to match unit analysis may be applied to all other crystalline materials, potentially optimizing EBSD analyses from a range of materials. Keywords: EBSD, microstructure, zircon, reflector file, match unit, REE, pressure, rare earth element

In this part of the work, the Eshelby tensors of a finite spherical domain are applied to various homogenization procedures estimating the effective material properties of multiphase composites. The Eshelby tensors of a finite domain can capture the boundary, effect of a representative volume element as well as the size effect of the different phases. Therefore their application to homogenization does not only improve the accuracy of classical homogenization methods, but also leads to some novel homogenization theories. This paper highlights a few of them: a refined dilute suspension method and a modified Mori-Tanaka method, the exterior eigenstrain method, the dual-eigenstrain method, which is a generalized self-consistency method, a shell model, and new variational bounds depending on the different boundary conditions. To the best of the authors' knowledge, this is the first time that a multishell model is used to evaluate the Hashin-Shtrikman bounds for a multiple phase composite (n [greater than or equal to] 3), which can distinguish some of the subtleties of different microstructures. [DOI: 10.1115/1.2711228]

The use of plastic materials with added fillers has become a potential alternative due their versatility and the ease of batch fabrication. Recently, micromolding has become a new branch of injection molding. One mold can be used to produce multiparts that weigh no more than a few milligrams and whose precision in terms of dimension is on the order of a few microns. This work investigates the shrinkage and accuracy of multiparts in one mold used in microinjection molding. In addition, the wear and mechanical properties of polymer composites with added fillers are systematically studied. Experiments showed that microparts with a 1.5 mm outer diameter were well duplicated, with clear structural definition. The average deviation in dimension was less than 20 [micro]m. The resulting composites with 20-25 wt% glass particles exhibited significant improvement in shrinkage, wear resistance, and mechanical strength. In addition, wear loss was minor, and lubrication was not needed when the roughness of the wearing surface was less than 0.064 [micro]m. POLYM. ENG. SCI., 45:1471-1478, 2005. [c] 2005 Society of Plastics Engineers, INTRODUCTION The development of microsystem technology on a vast scale is dependent on manufacturing systems that can reliably and economically produce microcomponents. The microinjection molding process, which permits cost-effective mass [...]

Byline: Laura Otero (1), Maria T. Solas (2), P. D. Sanz (1), Carlos de Elvira (1), Juan A. Carrasco (1) Keywords: Key wordsaHigh pressure; Freezing; Eggplant Abstract: aDamage to the microstructure of eggplants frozen by conventional air-freezing methods and by a high-pressure-assisted freezing method is compared in this paper. When conventional air-freezing techniques are employed, damage to the microstructure is enhanced as the freezing rate diminishes and the sample volume increases. However, when high-pressure-assisted freezing is applied, bulk nucleation occurs simultaneously in the whole sample, and the observed damage is less dependent on the volume of the sample. Author Affiliation: (1) Instituto del Frio (CSIC), Ciudad Universitaria, E-28040 Madrid, Spain, ES (2) Departamento de Biologia Celular, Universidad Complutense, E-28040 Madrid, Spain, ES Article note: Received: 8 April 1997 / Revised version: 24 November 1997