ALBERT

Notes: Oxide–sulphide–Fe–Mg–silicate and titanite–ilmenite textures as well as their mineral compositions have been studied in felsic and intermediate orthogneisses across an amphibolite (north) to granulite facies (south) traverse of lower Archean crust, Tamil Nadu, south India. Titanite is limited to the amphibolite facies terrane where it rims ilmenite or occurs as independent grains. Pyrite is widespread throughout the traverse increasing in abundance with increasing metamorphic grade. Pyrrhotite is confined to the high-grade granulites. Ilmenite is widespread throughout the traverse increasing in abundance with increasing metamorphic grade and occurring primarily as hemo-ilmenite in the high-grade granulite facies rocks. Magnetite is widespread throughout the traverse and is commonly associated with ilmenite. It decreases in abundance with increasing metamorphic grade. In the granulite facies zone, reaction rims of magnetite + quartz occur along Fe–Mg silicate grain boundaries. Magnetite also commonly rims or is associated with pyrite. Both types of reaction rims represent an oxidation effect resulting from the partial subsolidus reduction of the hematite component in ilmenite to magnetite. This is confirmed by the presence of composite three oxide grains consisting of hematite, magnetite and ilmenite. Magnetite and magnetite–pyrite micro-veins along silicate grain boundaries formed over a wide range of post-peak metamorphic temperatures and pressures ranging from high-grade SO2 to low-grade H2S-dominated conditions. Oxygen fugacities estimated from the orthopyroxene–magnetite–quartz, orthopyroxene–hematite–quartz, and magnetite–hematite buffers average 2.5 log units above QFM. It is proposed that the trends in mineral assemblages, textures and composition are the result of an external, infiltrating concentrated brine containing an oxidizing component such as CaSO4 during high-grade metamorphism later acted upon by prograde and retrograde mineral reactions that do not involve an externally derived fluid phase.

Notes: Silica-undersaturated, sapphirine-bearing granulites occur in a large number of localities worldwide. Such rocks have historically been under-utilized for estimating P–T evolution histories because of limited experimental work, and a consequent poor understanding of the topology and P–T location of silica-undersaturated mineral equilibria. Here, a calculated P–T projection for sapphirine-bearing, silica-undersaturated metapelitic rock compositions is constructed using THERMOCALC for the FeO-MgO-Al2O3-SiO2 (FMAS) and KFMASH (+K2O + H2O) chemical systems, allowing quantitative analysis of silica-undersaturated mineral assemblages. This study builds on that for KFMASH sapphirine + quartz equilibria [Kelsey et al. (2004) Journal of Metamorphic Geology, vol. 22, pp. 559–578]. FMAS equilibria are significantly displaced in P–T space from silicate melt-bearing KFMASH equilibria. The large number of univariant silica-undersaturated KFMASH equilibria result in a P–T projection that is topologically more complex than could be established on the basis of experiments and/or natural assemblages. Coexisting sapphirine and silicate melt (with or without corundum) occur down to c. 900 °C in KFMASH, some 100 °C lower than in silica-saturated compositions, and from pressures of c.≤1 to ≥12 kbar. Mineral compositions and composition ranges for the calculated phases are consistent with natural examples. Bulk silica has a significant effect on the stability of sapphirine-bearing assemblages at a given P–T, resulting in a wide variety of possible granulite facies assemblages in silica-undersaturated metapelites. Calculated pseudosections are able to reproduce many naturally occurring silica-undersaturated assemblages, either within a single assemblage field or as the product of a P–T trajectory crossing several fields. With an understanding of the importance of bulk composition on sapphirine stability and textural development, silica-undersaturated assemblages may be utilized in a quantitative manner in the detailed metamorphic investigation of high-grade terranes.

Notes: Several petrographic studies have linked accessory monazite growth in pelitic schist to metamorphic reactions involving major rock-forming minerals, but little attention has been paid to the control that bulk composition might have on these reactions. In this study we use chemographic projections and pseudosections to argue that discrepant monazite ages from the Mount Barren Group of the Albany–Fraser Orogen, Western Australia, reflect differing bulk compositions. A new Sensitive High-mass Resolution Ion Microprobe (SHRIMP) U–Pb monazite age of 1027 ± 8 Ma for pelitic schist from the Mount Barren Group contrasts markedly with previously published SHRIMP U–Pb monazite and xenotime ages of c. 1200 Ma for the same area. All dated samples experienced identical metamorphic conditions, but preserve different mineral assemblages due to variable bulk composition. Monazite grains dated at c. 1200 Ma are from relatively magnesian rocks dominated by biotite, kyanite and/or staurolite, whilst c. 1027 Ma grains are from a ferroan rock dominated by garnet and staurolite. The latter monazite population is likely to have grown when staurolite was produced at the expense of garnet and chlorite, but this reaction was not intersected by more magnesian compositions, which are instead dominated by monazite that grew during an earlier, greenschist facies metamorphic event. These results imply that monazite ages from pelitic schist can vary depending on the bulk composition of the host rock. Samples containing both garnet and staurolite are the most likely to yield monazite ages that approximate the timing of peak metamorphism in amphibolite facies terranes. Samples too magnesian to ever grow garnet, or too iron-rich to undergo garnet breakdown, are likely to yield older monazite, and the age difference can be significant in terranes with a polymetamorphic history.

Notes: Fan-shaped polycrystalline staurolite porphyroblasts, 3–4 cm in length and 0.5 cm in width, occur together with centimetre-sized euhedral prismatic staurolite porphyroblasts in pelitic schists of the Littleton Formation on the western overturned limb of the Bolton syncline in eastern Connecticut. The fans consist of intergrown planar splays of [001] elongated prisms, which are crudely radial from a single apex. The apical angles of the radial groupings range up to 70°. The orientations of the individual staurolite prisms are related by a rigid rotation about an axis perpendicular to the fan plane. The zone axes [001] always lie in the plane of the fan. Although the angle between the [100] zone axes of the individual prisms is uniform in each fan, it ranges from +30° to −30° in different fans. Internally, the fans display: (i) remnants of a passively captured Si foliation defined by disc-shaped quartz blebs (type 1 inclusions) and layers of very fine carbonaceous material and tabular ilmenite platelets; (ii) bent staurolite blades and undulose extinction along low-angle (010) subgrain boundaries near the apex of the fans; (iii) wedge-shaped dilatational zones containing equigranular inclusion-free quartz, mica and staurolite, and (iv) growth-related quartz inclusion trails roughly perpendicular to a crystal face (type 2 inclusions). The Si inclusion trails are typically perpendicular to the fan surface, radiate parallel to the blades, and show little to no curvature except at the very edge of the fans where they abruptly curve through nearly 90° into parallelism with an external Se foliation. Careful examination of the three-dimensional geometry of fans based on U-stage measurements, serial sections and two-circle optical goniometric measurements permits a detailed reconstruction of their sequential development. The origin of a fan involves limited intracrystalline deformation and brittle crack dilation, spalling, rotation, and growth of small marginal fragments and of new staurolite along wedge-shaped zones along the Si inclusion surfaces. Fans preferentially develop in porphyroblasts in which Si is subparallel to the 010 cleavage. These internal features reflect the rotation and deformation of a brittle porphyroblast relative to syn-growth shear stresses.

Notes: Detailed microtextural observations and bulk chemical analysis were undertaken on a garnet-pyroxenite nodule within retrograde eclogites from the NE Sulu ultrahigh-pressure metamorphic (UHPM) terrane. The results suggest that the protolith was a cumulate from a gabbroic body. The nodule consists primarily of coarse clinopyroxene grains with a very high content of the Ca-Tschermakite molecule. Microscopic observations and back-scattered electron images (BSE) demonstrate a complicated intergrowth of clinopyroxene, garnet and ilmenite, which represents the peak metamorphic assemblage. The primary clinopyroxene grains are armoured with a thin garnet corona up to 0.5 mm wide that forms an interconnected network. Within the clinopyroxene grains, four sets of garnet lamellae are distributed along crystallographic planes; locally, a vermicular intergrowth of garnet and diopside is developed. Besides the garnet, parallel arrays of ilmenite blebs are common within the clinopyroxene. Hydrous minerals such as amphibole, zoisite and titanite formed at later stages, and replaced diopside, garnet and ilmenite respectively. The P–T conditions determined for the formation of the garnet lamellae indicate that the garnet pyroxenite experienced UHP metamorphism at the same peak P–T condition as its host eclogite. The very high Ca-Tschermakite content (31–34 mol.%) of the primary clinopyroxene indicates crystallization at about 9–17 kbar and 1250–1450 °C, and together with the microtextural observations, suggests that the protolith of the garnet pyroxenite was a cumulate from a former gabbroic body, in which case, the host eclogite might represent the gabbroic body.

Notes: Thermodynamic calculations in petrology are generally performed at pressures and temperatures beyond the standard state conditions. Accurate prediction of mineral equilibria therefore requires knowledge of the heat capacity, thermal expansion and compressibility for the minerals involved. Unfortunately, such data are not always available. In this contribution we present a data set to estimate the heat capacity, thermal expansion and compressibility of mineral end-members from their constituent polyhedra, based on the premise that the thermodynamic properties of minerals can be described by a linear combination of the fractional properties of their constituents. As such, only the crystallography of the phase of interest needs to be known. This approach is especially powerful for hypothetical mineral end-members and for minerals, for which the experimental determination of their thermodynamic properties is difficult. The data set consists of the properties for 35 polyhedra in the system K–Na–Ca–Li–Be–Mg–Mn–Fe–Co–Ni–Zn–Al–Ti–Si–H, determined by multiple linear regression analysis on a data set of 111 published end-member thermodynamic properties. The large number of polyhedra determined allows calculation of a much larger variety of phases than was previously possible, and the choice of constituents together with the large number of thermodynamic input data results in estimates with associated uncertainty of generally 〈5%. The quality of the data appears to be sufficiently accurate for thermodynamic modelling as demonstrated by modelling the stability of margarite in the CASH system and the position of the talc–staurolite–chloritoid–pyrope absent invariant point in the KMASH system. In both cases, our results overlap within error with published equivalents.

Notes: The prograde pressure–temperature (P–T) path for the complexly polydeformed Proterozoic Broken Hill Block (Australia) has been reconstructed through detailed structural analysis in conjunction with calculation of compositionally specific P–T pseudosections of pelitic rock units within a high-temperature shear zone that formed early in the tectonic evolution of the terrane. Whilst the overall P–T path for the Broken Hill Block has been interpreted to be anticlockwise, the prograde portion of this path has been unresolved. Our results have constrained part of this prograde path, showing an early heating event (M1) at P–T conditions of at least c. 600 °C and c. 2.8–4.2 kbar, associated with an elevated geothermal gradient (c. 41–61 °C km−1). This event is interpreted to be the result of rifting at c. 1.69–1.67 Ga, or at c. 1.64–1.61 in the Broken Hill Block. Early rifting was followed by an episode of lithospheric thermal relaxation and burial, during which time sag-phase sediments of the upper Broken Hill stratigraphy (Paragon Group) were deposited. Following sedimentation, a second tectonothermal event (M2/D2) occurred. This event is associated with peak low-pressure granulite facies metamorphism (c. 1.6 Ga) and attained conditions of at least 740 °C at c. 5 kbar. A regionally pervasive, high-temperature fabric (S2) developed during the M2/D2 event, and deformation was accommodated along lithology-parallel, high-temperature shear zones. The larger-scale deformation regime (extensional or shortening) of this event remains unresolved. The M2/D2 event was terminated by intense crustal shortening during the Olarian Orogeny, during which time the first mappable folds within the Broken Hill Block developed.

Notes: A calibration is presented for an activity–composition model for amphiboles in the system Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O–O (NCFMASHO), formulated in terms of an independent set of six end-members: tremolite, tschermakite, pargasite, glaucophane, ferroactinolite and ferritschermakite. The model uses mixing-on-sites for the ideal-mixing activities, and for the activity coefficients, a macroscopic multicomponent van Laar model. This formulation involves 15 pairwise interaction energies and six asymmetry parameters. Calibration of the model is based on the geometrical constraints imposed by the size and shape of amphibole solvi inherent in a data set of 71 coexisting amphibole pairs from rocks, formed over 400–600 °C and 2–18 kbar. The model parameters are calibrated by combining these geometric constraints with qualitative consideration of parameter relationships, given that the data are insufficient to allow all the model parameters to be determined from a regression of the data. Use of coexisting amphiboles means that amphibole activity–composition relationships are calibrated independently of the thermodynamic properties of the end-members. For practical applications, in geothermobarometry and the calculation of phase diagrams, the amphibole activity–composition relationships are placed in the context of the stability of other minerals by evaluating the properties of the end-members in the independent set that are in internally consistent data sets. This has been performed using an extended natural data set for hornblende–garnet–plagioclase–quartz, giving the small adjustments necessary to the enthalpies of formation of tschermakite, pargasite and glaucophane for working with the Holland and Powell data set.

Notes: Integrated petrological and structural investigations of eclogites from the eclogite zone of the Voltri Massif (Ligurian Alps) have been used to reconstruct a complete Alpine P–T deformation path from burial by subduction to subsequent exhumation. The early metamorphic evolution of the eclogites has been unravelled by correlating garnet zonation trends with the chemical variations in inclusions found in the different garnet domains. Garnet in massive eclogites displays typical growth zoning, whereas garnet in foliated eclogites shows rim-ward resorption, likely related to re-equilibration during retrogressive evolution. Garnet inclusions are distinctly different from core to rim, consisting primarily of Ca-, Na/Ca-amphibole, epidote, paragonite and talc in garnet cores and of clinopyroxene ± talc in the outer garnet domains. Quantitative thermobarometry on the inclusion assemblages in the garnet cores defines an initial greenschist-to-amphibolite facies metamorphic stage (M1 stage) at c. 450–500 °C and 5–8 kbar. Coexistence of omphacite + talc + katophorite inclusion assemblage in the outer garnet domains indicate c. 550 °C and 20 kbar, conditions which were considered as minimum P–T estimates for the M2 eclogitic stage. The early phase of retrograde reactions is polyphase and equilibrated under epidote–blueschist facies (M3 stage), characterized by the development of composite reaction textures (garnet necklaces and fluid-assisted Na-amphibole-bearing symplectites) produced at the expense of the primary M2 garnet-clinopyroxene assemblage. The blueschist retrogression is contemporaneous with the development of a penetrative deformation (D3) that resulted in a non-coaxial fabric, with dominant top-to-the-N sense of shear during rock exhumation. All of that is overprinted by a texturally late amphibolite/greenschist facies assemblages (M4 & M5 stages), which are not associated with a penetrative structural fabric. The combined P–T deformation data are consistent with an overall counter-clockwise path, from the greenschist/amphibolite, through the eclogite, the blueschist to the greenschist facies. These new results provide insights into the dynamic evolution of the Tertiary oceanic subduction processes leading to the building up of the Alpine orogen and the mechanisms involved in the exhumation of its high-pressure roots.

Notes: One of the proximate results of forest fragmentation, and a cause of continued microenvironmental change and exacerbation of ecological problems, is increased invasions by weedy plant species. One such example is Alliaria petiolata (Brassicaceae), a serious pest threatening much of eastern North America. Alliaria petiolata impedes mitigation of fragmentation and restoration efforts because it tends to outcompete and possibly extirpate much of the native understory species on localized scales. As part of a strategy to address the problems of fragmented habitats, an experiment was conducted to determine whether Sanguinaria canadensis (Papaveraceae) could outcompete A. petiolata. Using an additive design, I transplanted S. canadensis at densities of 0, 1, 2, 3, 5, 7, 9, 11, 15, and 20 ramets/m2 in 1997 and allowed them to interact with initial A. petiolata densities of 128 seedlings and 31 rosettes/m2. As of 2000, multivariate analyses of variance with repeated measures and simple analyses of variance indicated that initial S. canadensis densities of as little as 5 ramets/m2 suppressed A. petiolata. Initial S. canadensis densities of 9 and 11 ramets/m2 resulted in the lowest numbers of late-spring seedlings, numbers and sizes of year 1 and 2 rosettes, numbers and gross areas of stem leaves, numbers of flowering individuals, number of flowers, number of fruits (siliques), and height at flowering. While it remains to be tested whether this will continue and if the reestablishment of S. canadensis will help reassemble forest ecosystems, the experiments indicated that transplanting S. canadensis was effective at mitigating the spread of A. petiolata.

Notes: Canebrakes are dense stands of Arundinaria gigantea (Walt.) Muhl. that covered large areas of the southeastern North America. With agricultural development, canebrakes were quickly converted to crop and pastureland and now occur only in small, isolated patches. There is growing interest in the use of A. gigantea and other temperate bamboo species in riparian and floodplain revegetation in North America, but lack of detailed information on propagation and management of woody perennial grasses hinders reestablishment activities. Our study assesses the influence of nutrient and woodchip mulch amendments on survival and growth of A. gigantea transplanted as part of a riparian restoration project in central Kentucky. After two growing seasons, culm number (aboveground stems) increased 4-fold and extent of transplanted clumps expanded 26-fold. The survival rate of transplanted cane clumps was 98%. Hardwood chip mulch significantly increased the emergence of new culms, culm height growth, and clump area. Composted manure, applied at a rate that contributed a similar mass of organic matter as the hardwood mulch, also significantly increased new culm number and clump area. Our findings demonstrate that addition of manure or hardwood mulch can significantly enhance aboveground production of A. gigantea transplants. However, survival and initial growth of untreated clumps were also adequate in this study. It appears that careful site selection, transplantation, and site maintenance may be sufficient to ensure A. gigantea establishment on many sites. Practitioners should assess soil drainage, water stress, and fertility along with herbaceous competition and incidence of overbank flooding before determining the necessity of organic amendments to supplement establishment of A. gigantea or other woody grasses for riparian restoration.

Notes: Constraints to grassland and open forest restoration (e.g., poor seed sources, yearly variation in establishment, and the persistence of weeds) necessitate the development of innovative methods to restore bunchgrass communities. We assessed the use of two native bunchgrass transplants, Bluebunch wheatgrass (Pseudoroegneria spicata) and Spreading needlegrass (Achnatherum richardsonii), for restoration within thinned montane forest communities of southeastern British Columbia, Canada. Fall and spring plantings were examined, either with or without glyphosate treatments to Pinegrass (Calamagrostis rubescens) neighbors. Calamagrostis rubescens is abundant in grassland affected by tree encroachment and may limit transplant establishment. Bunchgrass survival was positively associated (p 〈 0.05) with transplant size. Although P. spicata survival was greater (p 〈 0.01) with fall (81%) than with spring (44%) planting, survival of A. richardsonii was greater (p 〈 0.01) when planted in the spring (68 vs. 23%). Reduction of C. rubescens led to a relatively small but significant increase (p 〈 0.05) in bunchgrass survival by 7%. The summer after planting, changes in transplant tiller number varied by bunchgrass species, planting season, and treatment of neighboring C. rubescens. Removal of neighboring C. rubescens generally increased the number of tillers (or reduced tiller loss) but only within fall-planted A. richardsonii and spring-planted P. spicata. Both A. richardsonii and P. spicata transplants have potential for understory restoration within thinned montane forests, particularly using larger individuals, although to maximize survival, these species should be planted in the spring and fall, respectively. Reduction of C. rubescens may also enhance transplant survival and in some cases growth.

Notes: Carolina bays are depression wetlands of high conservation value that occur across the Southeastern Coastal Plain of the United States. Venus flytrap (Dionaea muscipula) is one rare carnivorous plant that grows in open habitats on the rims of Carolina bays. Without frequent burning, vegetation on bay rims becomes dominated by evergreen shrubs and Venus flytrap populations decline. This project examined the utility of mechanical mowing, soil clearing, transplanting, and seeding as an approach to restoring populations of Venus flytraps when fire is precluded. Mowing of patches on bay rims produced open sites with little ground-layer vegetation. After two growing seasons, adult Venus flytraps transplanted to mowed patches showed high survivorship and relatively high leaf number/plant. Suppressed Venus flytraps existing on-site quickly initiated growth in response to mowing. These volunteers and the transplants had higher flowering percentages than plants in reference populations. Seeds of Venus flytraps were scattered in mowed and cleared plots. Seedling establishment was low, but seedlings persisted into the second growing season. Mowing created suitable habitat for growth and flowering of adult Venus flytraps and facilitated establishment of two other carnivorous species, Sundew (Drosera capillaris) and Bladderwort (Utricularia subulata). But, mowing and clearing also facilitated invasion by four species of grasses and rushes; evergreen shrubs resprouted quickly after mowing. Maintaining persistent openings by mowing the rims of Carolina bays will be an ongoing challenge due to availability of potential invaders and rapid regrowth of shrubs.

Notes: Native plant establishment is limited by harsh environmental conditions in areas affected by tephra deposition following volcanic eruptions. Late-successional species might be lacking even decades after the disturbance. We assessed the effectiveness of pine-bark mulch, a by-product of sustainable timber production in the study area, in promoting the establishment and survival of a late-successional species (Pinus pseudostrobus) and a nitrogen-fixing legume (Lupinus elegans). We established a factorial experiment in areas covered with tephra during the eruption of the Paricutín volcano in the state of Michoacán, Mexico. After 1 year, P. pseudostrobus survival was significantly higher (p 〈 0.001) in plots with pine-bark mulching (46.5%) than in plots without mulching (21.8%). After 2 years, surviving pines with mulching were significantly taller (p= 0.03) than pines without mulching (45.3 ± 3.8 cm and 31.2 ± 3.7 cm, respectively). Lupinus elegans plants survived longer when grown in plots with pine-bark mulching than without mulching. Mulching reduced tephra temperatures during the dry season (when temperatures can reach up to 58°C 4 cm below the surface of bare tephra). Lupinus elegans plants were affected by herbivory by small rodents, run-off, and frost at the end of the growing season. Our results suggest that mulching can ameliorate harsh environmental conditions on sites covered with tephra while incorporating a by-product of sustainable forestry into restoration practice.

Notes: Bracken (Pteridium aquilinum) is a major weed of seminatural vegetation in Great Britain, as in many other countries. As a consequence, large areas have been subject to control with the intention of restoring the former vegetation. The use of aerial spraying with asulam, a narrow spectrum, carbamate herbicide, has become a common method of control. However, its long-term efficacy has not been assessed in terms of either controlling the bracken or in producing suitable restored habitats. This study undertook such an assessment by comparing the results of a 2002 survey of the sites subject to bracken control by aerial spraying of asulam with previous (1990/1991 and 1994) surveys of the same sites. This showed that a single application of asulam was effective in eradicating bracken (〈1% cover remaining) on a third of sites. However, on 10% of the sites, the bracken had regenerated completely (cover 〉80%) and on the remainder it was still present in patches (〉20% of quadrats), often at high density. More than half the sprayed sites had seen good recovery of moorland vegetation, the target of the restoration, because they were now classified as having upland heathland vegetation within the National Vegetation Classification. Considerable amounts of bracken control are grant aided as part of agri-environment schemes. These schemes should be adapted to encourage good practice, namely, intensive follow-up treatment by spraying any emerging fronds, and to encourage treatment of previously sprayed areas rather than spraying of new areas in order to protect previous investment of grant aid.

Notes: Invasions of North American grasslands by Spotted knapweed (Centaurea maculosa Lam.) are mediated in part by Spotted knapweed root exudation of (±)-catechin, a potent phytotoxin. Residual soil (±)-catechin may interfere with reestablishment of native grassland species even after Spotted knapweed populations are controlled. Grassland species that are resistant to (±)-catechin may be more successful for restoration of areas infested by Spotted knapweed. We evaluated the (±)-catechin resistance of 23 grassland species by measuring the effects of seven (±)-catechin concentrations (0–4.0 mg/mL) on seed germination, seedling root and shoot elongation, and seedling mortality. (±)-Catechin treatments were chosen to reflect the range of observed Spotted knapweed field soil (±)-catechin concentrations. Inhibition of root elongation was the strongest and most common effect of (±)-catechin treatment. High (±)-catechin concentrations reduced mean root lengths of 5 of the species by more than 75% and another 10 species by more than 55%. Experimentally derived concentrations needed to reduce root length by 50% (EC50), an indicator of (±)-catechin resistance, ranged from 0.43 mg/mL ± 0.30 SE to greater than 4.0 mg/mL among species. Eight species with EC50s greater than 3.0 mg/mL were identified as resistant to (±)-catechin and are likely suitable for revegetation of Spotted knapweed–infested areas. (±)-Catechin resistance was positively correlated with mean seed mass, suggesting that seed carbohydrate reserves may allow seedlings to detoxify (±)-catechin, develop barriers to (±)-catechin exposure, or sustain a positive growth rate, despite (±)-catechin-induced cell death. Future efforts to identify allelochemical-resistant grassland species should focus on large-seeded species.

Notes: In plant conservation, restoration (the augmentation or reestablishment of an extinct population or community) is a valuable tool to mitigate the loss of habitat. However, restoration efforts can result in the introduction of novel genes and genotypes into populations when plant materials used are not of local origin. This movement is potentially important because many plant species are subdivided into populations that are adapted to local environmental conditions. Here we focus on genetic concerns arising from ongoing restoration efforts, where often little is known about “How local is local?” (i.e., the geographic or environmental scale over which plant species are adapted). We review the major issues regarding gene flow and local adaptation in the restoration of natural plant populations. Finally, we offer some practical, commonsense guidelines for the consideration of genetic structure when restoring natural plant populations.

Notes: Ecological restoration often relies on the use of expert opinion to make management decisions in the face of uncertainty. The quantification of expert opinion can be difficult, especially when more than one expert is consulted and experts are not in agreement. Decision analysis can provide a framework to systematically deconstruct a complex problem and provide greater objectivity to restoration decisions. We utilized decision analysis techniques to identify restoration objectives and to quantify expert opinions to prioritize restoration activities at 112 prairie openings in the Edge of Appalachia Preserve in southern Ohio, U.S.A. We first created an objectives hierarchy to model how decision-makers decide which prairies to manage. We then determined how to measure each component of the hierarchy and sampled all prairies for percent woody cover, geology, indicator species index (an index of plant species richness), slope, aspect, and distance to nearest prairie. We modeled seven different experts’ preferences for managing prairies with varying values for each of these ecological measures. We then interviewed the same decision-makers to determine relative weights for each component of the objectives hierarchy using trade-off analysis. By combining the weights, preference relationships, and sampling data, we were able to rank each prairie and management unit based on its management priority. Experts had similar preferences except for the measure of distance to nearest prairie. We found that decision-makers gave different weights to each of the different components of the hierarchy. Generally, experts weighted percent woody cover, indicator species index, and geology more highly than slope, aspect, and distance to nearest prairie. Despite these differences, priorities for management, once all factors were weighted and combined, were similar.

Notes: The Karner blue butterfly (KBB) (Lycaeides melissa samuelis), a federally listed species, has historically been a component of barren and savannah ecosystems in the northeastern and midwestern United States. In New York, it now occurs primarily on managed, early-successional sites such as power line corridors (utility rights-of-way) from Albany to Glens Falls. Blue lupine (Lupinus perennis), the exclusive larval food source of the KBB, has been suggested to be the most limiting factor for the butterfly within the eastern portion of its range. Power line corridor management maintains early-successional habitats by suppressing the regrowth of woody species, creating potentially important habitat for the conservation and restoration of the KBB complex. This research compared the effects of several vegetation-clearing methods on Blue lupine populations and associated communities of nectar species for KBB over an 8-year period. Methods evaluated differed in intensity (annual, 4-, or 8-year intervals) and type (herbicide or mechanical). Blue lupine and plant community responses did not significantly differ among the treatment types applied to the power line corridors. However, Blue lupine cover, clump size, and density of stems per clump increased following the application of treatments in general. The number and cover of nectar species, total herbaceous cover, and species richness also responded positively to treatment overall. The percentage of non-native species temporarily increased following treatment but declined to near pre-treatment levels again as woody cover increased. Temporal changes in plant community composition were not related to management methods. The management tools assessed, mowing and herbicide application, will accomplish the goal of halting or reversing succession, maintaining critical habitat for the KBB in a landscape that provides little other suitable habitat.

Notes: Replacement of perennial grasses with non-native annual grasses in California's Central Valley grasslands and foothills has increased deep soil water availability. Yellow starthistle (Centaurea solstitialis), a deep-rooted invasive thistle, can use this water to invade annual grasslands. Native perennial bunchgrasses, such as Purple needlegrass (Nassella pulchra), also use deep soil water, so there is an overlap in resource use between N. pulchra and C. solstitialis. Restoration of N. pulchra to annual grasslands could result in strong competitive interactions between N. pulchra and C. solstitialis, which may reduce survival, growth, and reproduction of the invader. The strength of this competitive interaction can increase as N. pulchra plants mature, increase in size, and develop more extensive root systems. We studied how the size of N. pulchra affected the success of C. solstitialis invasion over 2 years. We allowed C. solstitialis seed to fall naturally into plots containing N. pulchra plants. For each plot, we measured the number of C. solstitialis seedlings and mature plants, as well as C. solstitialis biomass and seedhead production. In both years of the study, C. solstitialis number, biomass, and seedhead production declined significantly as N. pulchra size increased. However, even C. solstitialis grown with the largest N. pulchra plants produced some seed, especially during the higher rainfall year. We conclude that restoration plantings with larger, established N. pulchra plants will be more resistant to invasion by C. solstitialis than young N. pulchra plantings, but site management must continue as long as a C. solstitialis seed source is present.

Notes: A study was conducted to evaluate the long-term effects of biosolids amendment on restoration of disturbed sagebrush steppe habitat in northwestern Colorado. Twenty-four years after biosolids amendment, soil fertility and plant community development were studied in replicated plots receiving various biosolids amendments on two different substrates. The two substrates used were a subsoil, determined to have low initial fertility, and a topsoil over retorted shale substrate, determined to have relatively high initial fertility. Results suggest that biosolids amendments have long-lasting effects on soil fertility and plant community composition, but these effects vary between the two substrates that were utilized. Within the plots established on subsoil, the long-term effect of biosolids was a reduction in plant species diversity and dominance by perennial grasses. On the topsoil substrate, there was a decrease in perennial grasses and an increase in shrub dominance with increasing biosolids. Results demonstrate the importance of considering initial soil conditions, seed mixture, and biosolids application rate when using biosolids for restoration of disturbed sagebrush steppe habitat. The long-term effects of the biosolids treatments at this site demonstrate the need to consider restoration treatment effects over longer and more ecologically meaningful time frames.

Notes: Non-native fish generally cause native fish decline, and once non-natives are established, control or elimination is usually problematic. Because non-native fish colonization has been greatest in anthropogenically altered habitats, restoring habitat similar to predisturbance conditions may offer a viable means of non-native fish control. In this investigation we identified habitats favoring native over non-native fish in a Mojave Desert oasis (Ash Meadows) and used this information to restore one of its major warm water spring systems (Kings Pool Spring). Prior to restoration, native fishes predominated in warm water (25–32°C) stream and spring-pool habitat, whereas non-natives predominated in cool water (≤23°C) spring-pool and marsh/slack water habitat. Native Amargosa pupfish (Cyprinodon nevadensis) and Ash Meadows speckled dace (Rhinichthys osculus nevadensis) inhabited significantly faster mean water column velocities (MWCV) and greater total depth (TD) than non-native Sailfin molly (Poecilia latipinna) and Mosquitofish (Gambusia affinis) in warm water stream habitat, and Ash Meadows speckled dace inhabited significantly faster water than non-natives in cool water stream habitat. Modification of the outflow of Kings Pool Spring from marsh to warm water stream, with MWCV, TD, and temperature favoring native fish, changed the fish composition from predominantly non-native Sailfin molly and Mosquitofish to predominantly Ash Meadows pupfish. This result supports the hypothesis that restoring spring systems to a semblance of predisturbance conditions would promote recolonization of native fishes and deter non-native fish invasion and proliferation.

Notes: Rainforest fragmentation and creek degradation are major problems on the Atherton Tablelands in North Queensland. Lake Barrine and Wooroonooran National Parks are separated by a 1.5-km length of Toohey's Creek which has been cleared except for small remnant rainforest patches. The creek has been fenced and replanted to create a corridor between the two national parks. The aim of this study was to monitor the success of the corridor in providing habitat for rainforest birds. Avian communities were monitored in the corridor and in adjacent rainforest sites using point counts over the period of reestablishment of a continuous rainforest canopy. In terms of bird community composition, within 3 years of planting, the replanted sites were on a trajectory toward the rainforest sites. Although specialist rainforest species were not yet found in the plantings, after 3 years those species which mainly inhabit rainforest but also utilize edges and riparian strips were found in similar numbers in the plantings and in the small remnant patches along the corridor. Frugivorous species were quite abundant even in the youngest plantings. Thus, replanting of rainforest trees along Toohey's Creek has begun to provide habitat for some rainforest birds. It also shows good potential to act as a corridor to connect the previously isolated patches of rainforest for these species and to develop in habitat complexity as the frugivorous birds bring in rainforest plant species from nearby areas.

Notes: Many semiarid rangelands in the Great Basin, U.S.A., are shifting dominance to woody species as a consequence of land degradation including intense livestock grazing and fire suppression. Whereas past rehabilitation efforts in Big sagebrush (Artemisia tridentata) steppes removed the shrub and added introduced forage grasses to successfully shift communities from shrublands to grasslands, current consensus is that native species should be included in restoration projects and that retention of some woody plants is desirable. We examined the potential for interseeding grasses into dense shrub communities as a precursor to thinning shrubs and releasing grasses from shrub interference. We compared seedling establishment of the native grass, Bluebunch wheatgrass (Pseudoroegneria spicata), with that of the Eurasia grass, Crested wheatgrass (Agropyron desertorum), in dense Ar. tridentata stands. Shrubs may play an important role as nurse plants for seedling establishment (reduced solar radiation, “island of fertility” effect) but result in highly contrasting light environments and root interference for seedlings. In experimental plots, we examined effects of Ar. tridentata shade levels (0, 40, 70, and 90% reduction of solar radiation) and initial root exclusion (present/absent) on the establishment and growth of P. spicata and Ag. desertorum seedlings. With this design we evaluated the interference effects of Ar. tridentata on the two grasses and identified the most beneficial microsites for grass restoration in Ar. tridentata–dominated communities. We predicted seedling survival and growth to be greater under moderate shade (40% reduction) and limited root competition than under no or strong shade conditions (0 and 90%) and unrestricted root interactions. Fifty to 85% of the P. spicata and Ag. desertorum seedlings survived the dry summer months of 1995 and 1996 and the intervening winter. Neither shading nor root exclusion from Ar. tridentata affected final seedling survival of either species. Seedling biomass of both grass species was negatively affected by initial root interactions with Ar. tridentata. However, the analysis of seedling biomass variability (coefficient of variation) indicated that in all shade and root-exclusion treatments, some seedlings of both species developed to large individuals to survive in Ar. tridentata–dominated rangelands. Thus, the use of interseeding techniques shows promise for restoring herbaceous species in dense Ar. tridentata stands and should be given further consideration when shrub retention is an important consideration.

Notes: Preventing and controlling exotic plants remains a key challenge in any ecological restoration, and most efforts are currently aimed at local scales. We combined local- and landscape-scale approaches to identify factors that were most closely associated with invasion of riparian forests by exotic shrubs (Amur honeysuckle [Lonicera maackii] and Tatarian honeysuckle [L. tatarica]) in Ohio, U.S.A. Twenty sites were selected in mature riparian forests along a rural–urban gradient (〈1–47% urban land cover). Within each site, we measured percent cover of Lonicera spp. and native trees and shrubs, percent canopy cover, and facing edge aspect. We then developed 10 a priori models based on local- and landscape-level variables that we hypothesized would influence percent cover of Lonicera spp. within 25 m of the forest edge. To determine which of these models best fit the data, we used an information-theoretic approach and Akaike's information criterion. Percent cover of Lonicera was best explained by the proportion of urban land cover within 1 km of riparian forests. In particular, percent cover of Lonicera was greater in forests within more urban landscapes than in forests within rural landscapes. Results suggest that surrounding land uses influence invasion by exotic shrubs, and explicit consideration of land uses may improve our ability to predict or limit invasion. Moreover, identifying land uses that increase the risk of invasion may inform restoration efforts.

Notes: The extent of impairment to some Appalachian watersheds from acid precipitation is so extreme that watershed scale analytical tools are needed to help guide cost-effective management decisions. The objective of this study was to develop a measure of the functional value of streams as potential areas for juvenile Brook trout recruitment. This measure, which we term “weighted potential recruitment area” (WPRA), is a function of the expected Brook trout spawning intensity and juvenile survivorship. Estimates of WPRA for each stream segment were then used to identify restoration priorities and optimal restoration programs in the upper Shavers Fork watershed in West Virginia, U.S.A. Using this approach, we determined that the watershed has lost nearly 80% of its historic juvenile recruitment potential as a result of acid precipitation. We also determined that of the 145 stream segments in the watershed, eight critical stream segments account for nearly 20% of the loss. The costs and ecological benefits of a series of five alternative restoration programs were then assessed using an ArcGIS model (Environmental Systems Research Institute, Redlands, CA, U.S.A.). This approach identified two “optimal” alternatives: (1) a low-cost, moderate-benefit approach that would use existing rail access to treat acidification in three critical headwater locations and (2) a high-cost, high-benefit approach that would use aerial limestone application to treat numerous acidic tributaries near their source. The measure of stream ecological value that we developed was effective in identifying critical restoration priorities and optimal restoration strategies in this watershed. A similar procedure could be used to guide watershed restoration decisions throughout the Appalachian region.

Notes: The effective Young's moduli of co-continuous Al–Al2O3 composites over the 5–97 vol% Al2O3 composition range were experimentally measured and compared with theoretical composite modulus values predicted using the methods of Ravichandran, Tuchinskii, Hashin-Shtrikman, and the effective medium approximation (EMA). The influence of phase morphology and the modulus ratio (E1/E2) of the constituent phases on the resulting experimental and calculated Young's modulus is discussed. For two-phased co-continuous composites with a modulus ratio greater than 5, the EMA, with an appropriate microstructural shape factor, was the most consistent method for approximating the composite Young's modulus over the entire composition range.

Notes: Three different series of porous silicon nitride ceramics with volume fraction porosities in the range 0–0.5 were fabricated using different preparation routes: (i) partial sintering, (ii) the addition of fugitive inclusions, and (iii) partial hot pressing. The use of different sintering additives and firing conditions, depending on the preparation route, gives rise to different materials within a certain porosity range with variations in terms of microstructure and grain boundary phase. Mechanical properties, elastic moduli, and strength have been evaluated separately for each series of materials. Porosity dependences of Young's modulus, shear modulus, Poisson's ratio, and fracture strength have been assessed and a comparison of the different materials is made and discussed in relation to their microstructural features.

Notes: Monodisperse, spherical, and nonporous zirconia particles ranging from submicrons to microns for use as supports for capillary electrophoresis and chromatography were synthesized by the controlled hydrolysis of zirconium tetra-alkoxides in alcohol solutions in the presence of long-chain organic acids. Particle characteristics varied as a function of water concentration, the chain length of the organic acid, aging time, temperature, and extent of stirring. Changing these experimental parameters affected particle size, particle size distribution, and the degree of particle aggregation. Submicron particles were made by increasing the water concentration and decreasing aging time. Particle size increases as temperature during the aging period increases. Most importantly, large monodisperse particles (4 μm) could be made by extended stirring. In general, we found that particle size increases as the chain length of the organic acid increases. We also found that gentle rotation during the aging period prevented both particle settling and secondary nucleation. This allowed the production of large particles. BET nitrogen adsorption uptake measurements demonstrate that the particles could be sintered, without aggregating them, to remove virtually all internal porosity.

Notes: Fabrication of microstructures has been the subject of considerable attention in recent years. Techniques such as surface silicon micromachining and bulk silicon etch have emerged as practical methods for thin microstructures and processes such as LIGA (an acronym for the German words for lithography, electrodeposition, and molding) are being used to produce high aspect ratio structures from a limited set of electroformable metals and polymers. As microsystem technologies and application prospects continue to grow, it is of interest and much practical value to expand the material choices for LIGA-scale microstructures to ceramics and a broader class of metals. To this end, this paper investigates a new technique for the fabrication of high aspect ratio ceramic or metal microparts. This technique is based on capillary-driven microcasting and curing of an epoxy-based metallic or ceramic nanoparticulate slurry into a sacrificial plastic mold produced by microinjection molding. The cured preform is subsequently heated to remove the organic phase and to sinter the particulate ceramic or metallic phase. The fabrication process is discussed in the paper along with illustration of example microparts produced using the process. A theoretical model of the fluid flow during the microcasting process is developed and validated with experimental data from the fabrication of rectangular rib sections.

Notes: Compression molding of glass aspherical lenses has become a viable manufacturing process for precision optics. The widespread use of this process has been hampered by the lack of its fundamental understanding. This research is a part of the ongoing effort to understand some of the issues related to the process. Simple lens molding experiments were performed on a commercial precision lens molding machine. A finite element method (FEM) program was used to create a simple numerical model and analyze the molding process. Experimental results show that this process is capable of producing precision optical components. A comparison of the experimental results with the predicted results indicates that with a more sophisticated numerical model, it is possible to use FEM as a tool for process analysis.

Notes: A model and numerical framework is developed for piezoelectric materials. The model treats the piezoelectric and electrostrictive effects by incorporating orientation-dependent, single-crystal properties. The method is implemented in Object Oriented Finite Element program, a public domain finite element code, so it can be applied to arbitrary two-dimensional microstructures with crystallographic anisotropy. The model is validated against analytic solutions. Consistency of the method for known cases permits application of the technique to more complicated two-dimensional systems. The piezoelectric and electrostrictive response is determined for a few simple device geometries and provides insight for design and convergence criteria.

Notes: Molecular dynamic simulations of glasses belonging to the anorthite–diopside system have been performed in order to obtain an atomistic description of the material's structure. The structural parameters obtained by the simulations allow to confirm that the glass materials are characterized by a very similar short-range environment. The main differences have been observed in the intermediate-range order of the structure that describe the distribution and the packing of the tetrahedra constituting the three-dimensional networks. It is shown that the glass materials with composition close to the two extremes, corresponding to the pure glass anorthite or pure glass diopside, display the typical structural features of the tectosilicates and inosilicates subclass of minerals, respectively, to which anorthite and diopside crystals belong.

Notes: 3-D ordered macroporous sol–gel bioactive glass particles (3DOM-BG, pore size: 345 nm; molar composition: 75 SiO2–21 CaO–4 P2O5) were converted into nano-crystalline calcium-deficient carbonate apatite after soaking at 37°C in simulated body fluid. The as-formed, flake-like apatite transformed into a coral-like, highly crystalline hydroxyapatite with a minor tri-calcium phosphate phase after heating for 1 h at a temperature of 700°C. Fourier transform infrared results show the loss of carbonate and isolation of hydroxyl during heating. The heat treatment improved the apatite's resistance to dissolution in a buffer solution (pH=5).

Notes: Engineering tests and full-field strain measurements are used to assess the accuracy of predictions made by the Binary Model, a computational tool for textile composites. The test case is a carbon fiber/SiC matrix composite, in which the reinforcement is a three-dimensional angle-interlock weave. The test composites are thin, having been designed for heat exchanger applications. The thinness leads to strong variations in local strains and strong effects of tow waviness upon macroscopic elasticity. The model performs well in predicting both local variations in strain and macroscopic elasticity. The effect of averaging local strains over variable gauge lengths is explored. Strains averaged over an appropriate gauge length have recently been proposed as the preferred measures of strain for use in local failure criteria.

Notes: A temperature-induced gelation method has been developed for the preparation of sialon green bodies composed of Si3N4, AlN, Y2O3, and Al2O3. Using a polyester/polyamine condensation polymer as dispersant, stable suspension containing sialon, precursor powders could be prepared in methyl ethyl keton (MEK)/ethanol (E) solvent mixture with solids loading as high as 60 vol%. The solvency of the dispersant in MEK/E decreased dramatically on cooling. The sedimentation tests showed that the settling behavior changed from slow accumulation at ∼20°C to fast deposition of clusters at −15°C, because of the collapse of dispersant chains adsorbed at the surface of the particles. Steady shear viscosity and oscillatory measurements performed for 60 vol% suspensions as functions of temperature and added amounts of dispersant proved that suspensions were of low viscosity and high stability at room temperature, becoming predominantly very highly viscous and elastic as temperature decreased. The gelation mechanism was mainly based on the coiling up of dissolved dispersant molecules, inducing in situ gelation and the formation of a rigid network bridging the suspended particles. The green bodies showed negligible shrinkage during gelation, a small shrinkage during drying, homogeneous microstructures, narrow pore size distributions, and high relative density. It was possible to achieve dense α-sialon ceramics through pressureless sintering at 1750°C for 2 h.

Notes: Mechanical stress–strain behavior of LaCoO3, La0.8Ca0.2CoO3, and La0.7Ca0.3CoO3 was studied under compression at 25° and 300°C. A hysteresis in the stress–strain relationship due to reorientation of ferroelastic domains (deformation twins) was observed, and a remanent strain is measured after unloading. The cohersive stress, defined as the maximum in effective elastic compliance during first loading, increases with substitution of Ca for La and decreases with increasing temperature. Domain reorientation was confirmed by X-ray diffraction of surfaces parallel and perpendicular to the loading direction. LaCoO3 can be regarded as a soft ferroelastic material while the 30% Ca-substituted material is a hard ferroelastic. The hysteresis of the stress–strain relationship was clearly dependent on both composition and temperature.

Notes: Ceramic laminates exhibiting a threshold strength have been fabricated by dip-coating thick tape-cast Al2O3 layers into slurries containing mixtures of Al2O3 and either unstabilized zirconia (MZ-ZrO2) or mullite to produce thin compressive layers via both a molar volume change and a differential thermal contraction. Porosity was introduced into the thin compressive layers by adding rice starch to the dip-coating slurries, which decomposed during densification of the laminate. As the volume fraction of porosity is increased, the residual compressive stress (σC), as measured by piezospectroscopy, is reduced and approaches zero at approximately 0.65 volume fraction of porosity. The elastic modulus mismatch (E1/E2) between the thin and thick laminate layers accounted for approximately one-half of the threshold strength for volume fractions of porosity ≤0.30 (E1/E2〈0.4). Above 0.40 volume fraction of porosity, the strength significantly increased as did the scatter in strength values, and it was observed that the highly porous layers completely arrested crack extension; these materials no longer exhibited a threshold strength. For these laminates, failure occurred by the independent, sequential failure of one layer after another, followed by catastrophic failure due to delamination.

Notes: Single-phase silicon carbide (SiC) nanotubes were successfully synthesized by the reaction of carbon nanotubes with silicon powder at 1200°C for 100 h. X-ray diffraction patterns indicated that most of the carbon from the carbon nanotubes that were reacted with silicon at 1200°C for 100 h was transformed to SiC. Transmission electron microscopy observations revealed that both single-phase SiC nanotubes and C–SiC coaxial nanotubes, which are carbon nanotubes sheathed with a SiC layer, were synthesized after 100 h of reaction. The ratio of single-phase SiC nanotubes to C–SiC nanotubes increased with heat treatment at 600°C in air for 1 h because the remaining carbon was removed.

Notes: Long crack R-curve of a porous Si3N4 with aligned fibrous grains was investigated, using a chevron-notched beam technique. A crack was constrained to propagate normal to the grain alignment. The crack growth resistance of aligned porous Si3N4 was much larger compared with that of dense Si3N4 ceramics. Microstructure observations showed that pullouts of fibrous grains in aligned porous Si3N4 markedly increased during crack propagation relative to those of dense Si3N4, due to the existence of pores. The efficient grain pullouts in porous Si3N4 increased the bridging stress at the crack wake.

Notes: Hydroxyapatite (HA) is an interesting ceramic material for orthopedic applications, in particular for implant operations and bone regeneration, owing to its bioactivity and biocompatibility with the surrounding tissues. Even if different shaping processes can be used in order to obtain porous ceramic bodies with optimal final properties, the sponge impregnation method with aqueous HA dispersions is particularly suitable to achieve an appropriate macroporosity to bone regeneration. As for conventional slip or tape casting, the rheological behavior of HA suspensions must be properly fitted to process conditions and controlled through a satisfactory stabilization of the disperse phase, i.e., through an appropriate dispersant dosage and an accurate homogenization of dispersed powder. In the present work, HA powders with different crystallinity degree were used to prepare aqueous dispersions with different contents of solids and dispersant (ammonium polyacrylate). The specific surface area of HA powders is very high, and then special attention must be dedicated to the dispersant selection and the dispersion process since the rheology of HA suspensions is strongly influenced by the structural conditions of the disperse phase. Even small differences in dispersant concentration can lead to dramatic changes in the rheological properties also at relatively low values of solids volume concentration. Above a critical concentration, the viscosity drop associated with the apparently plastic behavior is confined within a very narrow stress range, a neat transition is observed in the linear viscoelastic properties, and the time-dependent effects induced by the shear history become quite important and crucial for the experimental characterization.

Notes: Pristine, Si-doped, and Si/Nd-codoped yttrium aluminum garnet (YAG) nanoparticles were synthesized by pyrolysis of complex compounds of aluminum and yttrium with triethanolamine. It was found that the coexistence of Si4+ and Nd3+ increased the solubility of both ions and promoted the formation of YAG phase. Single-phase, nanocrystalline Si/Nd:YAG powders were obtained at calcination temperatures as low as 920°C. The optical behavior of the Si/Nd:YAG nanopowders was similar to that of single-crystal Nd:YAG.

Notes: Alumina bilayers of different relative thicknesses and densities were produced with a strong interface using a modified gel-casting technique. Tolerance to surface damage is examined using biaxial flexure of disks damaged with a single Vickers indentation at various loads. The greatest surface flaw tolerance is seen in bilayers consisting of a thin porous layer on the tensile surface coupled to a thick dense layer. Here, the modulus mismatch causes redistribution of the applied stress, and fracture initiates at the internal porous-dense interface rather than at the surface from the introduced indentation flaw.

Notes: An extensive X-ray study of CeO2–Nd2O3 solid solutions was performed, and the densities of solid solutions containing various concentrations of NdO1.5 were measured using several techniques. Solid solutions containing 0–80 mol% NdO1.5 were synthesized by coprecipitation from Ce(NO3)3 and Nd(NO3)3 aqueous solutions, and the coprecipitated samples were sintered at 1400°C. A fluorite structure was observed for CeO2–NdO1.5 solid solutions with 0–40 mol% NdO1.5, which changed to a rare earth C-type structure at 45–75 mol% NdO1.5. The change in the lattice parameters of CeO2–NdO1.5 solid solutions, when plotted with respect to the NdO1.5 concentration, showed that the lattice parameters followed Vegard's law in both the fluorite and rare earth C-type regions. The maximum solubility limit for NdO1.5 in CeO2 solid solution was approximately 75 mol%. The relationship between the density and the Nd concentration indicated that the defect structure followed the anion vacancy model over the entire range (0–70 mol% NdO1.5) of solid solution.

Notes: Yttrium silicates are promising materials for improved oxidation and erosion protection for carbon fiber-reinforced composites. A two-layer coating system of low-pressure plasma-sprayed yttrium silicate on chemical vapor deposition-SiC-precoated C/C–SiC was tested under atmospheric re-entry conditions simulated within a plasma wind tunnel test facility. The thermal expansion behavior of Y2SiO5 and Y2Si2O7 was investigated. The chemical compatibility with and without increasing oxygen partial pressure at the interface of the two-layer system was calculated by the CALPHAD method. The calculations were compared with experimental results. Furthermore, a thermodynamic explanation is presented to understand and predict the observed coating failure mechanism, identified as blister formation.

Notes: The early stage of phase separation in aluminoborosilicate glass for liquid crystal display substrates was investigated using a scanning electron microscope (SEM) and small-angle X-ray scattering measurement device (SAXS). The phase-separated particles were detected with SAXS in samples in which no particle was observed with SEM. The particle diameter in an as-formed sample was 2 nm. The relationship between the diameter and heat-treatment time indicates that the phase separation proceeds by a diffusion-controlled process. Based on the results of Fourier-transform infrared spectroscopy, fast compositional change may occur in the early stage of phase separation.

Notes: Tin (Sn) substitution for titanium (Ti) was investigated in Ba6−3xNd8+2xTi18O54 (x=1/2, 2/3, and 3/4) ceramics. A small amount (z〈0.1) of Sn substitution resulted in Ba6−3xNd8+2x(Ti1−zSnz)18O54 solid solutions, and some secondary phases were observed with increasing Sn content. A small amount of Sn substitution improved the Qf value significantly, while, due to the formation of secondary phases, the Qf value degraded sharply for larger Sn content. The relative dielectric constant (ɛr) decreased with increasing Sn-content, while the temperature coefficient of resonant frequency (τf) generally decreased, although an obvious fluctuation was observed for x=3/4.

Notes: In this paper we report the synthesis of polygonal single-crystal aluminum borate microtubes by the direct calcination of alumina and boron nitride powders in air. The diameters of the obtained tubes vary between 1 and 15 μm; and the lengths are in the range of tens to hundreds of micrometers. The cross-sections of the microtubes are in the shapes of rectangular, hexagonal, and quasi-circle. A new solid–liquid–solid growth mechanism was proposed to account for the formation of microtubes instead of whiskers.

Notes: Leaf litter is an important source of organic matter as nutrients for aquatic and terrestrial microbial communities. Biogenic decomposition of leaf litter contributes substantially to atmospheric CO2, possibly producing global warming, and comprises an important part of the terrestrial carbon cycle. Small-scale variability in terrestrial protozoan communities may be attributed to localized variations in leaf matter. This study examined the effect of aqueous leaf extracts from four trees (beech, maple, red oak, and white oak) on the abundance and diversity of protozoa in laboratory aquatic and soil cultures. Beech leaf extract was the most productive followed in the descending order by white oak, red oak, and maple in both aquatic and soil microcosm cultures. Dilution experiments indicated that concentration-related inhibitory substance(s) in the maple and red oak leaves contribute to lower productivity. Removal of tannins by treatment with activated charcoal (Norit®) improved productivity especially for red oak leaf extracts, suggesting that tannins may contribute to the inhibition of protozoan standing stock. To determine if the lower productivity was mainly due to the inhibition of protozoan excystment, aliquots of thoroughly dried soil were inoculated into maple and red oak leaf extracts. A comparable growth of protozoa occurred in these treatments as in aliquots from moist soil indicating that inhibition of excystment is not a likely explanation for reduced productivity of the protozoan communities.

Notes: The stalked ciliate, Vorticella convallaria, is a good model system to study mechanochemical motility because its contractile organelles (spasmoneme and myonemes) use a mode of contraction that differs from most other eukaryotic motile systems. Since calcium triggers this contraction, we have undertaken the molecular characterization of the calcium-binding proteins associated with these organelles. We have isolated and identified seven unique centrin-like cDNAs from V. convallaria. Each encodes an acidic protein of approximately 20-kDa, containing a unique N-terminus and four potential calcium-binding domains. We predict that each centrin has a distinct function within the cell. To define these functions, we have initiated immunofluorescence localization studies utilizing various anti-centrin antibodies. Western analysis indicates that each antibody recognizes a distinct protein or subset of proteins in Vorticella. Using these antibodies, we have localized centrin to various structures within the cell; myonemes, spasmoneme, and the oral apparatus. Because each of these antibodies recognizes a different protein on Westerern analysis, we conclude that a number of calcium-binding proteins are associated with the contractile organelles. To further characterize this gene family, we have initiated immunolocalization at the ultrastructural level. This will permit subcellular localization of all Vorticella centrins and enable us to dissect the function of this multi-gene family.

Notes: A previous survey of Euplotes genes available in GenBank indicated that 〉5% required a +1 translational frameshift for expression, much higher than observed in other organisms. Because this sample of sequences was non-random and biased towards highly expressed genes, we have randomly selected and sequenced 25 Euplotes crassus macronuclear DNA molecules to more accurately assess the frequency of frameshifting. Three new +1 frameshift genes were identified, and all have sequence features similar to the previously postulated frameshift sites. The results indicate that the frequency of Euplotes+1 frameshift genes is indeed high, and likely 〉10%. We have also examined the evolution of one of two frameshift sites present in the telomerase reverse transcriptase (TERT) genes of E. crassus. TERT gene segments were isolated from five additional Euplotes species. FS2 was found only in E. crassus and the closely related E. vannus, and phylogenetic analyses indicate that the site arose late in the evolution of the Euplotes group. Moreover, a novel frameshift site (FS3) was identified solely in the TERT gene of E. minuta. These results indicate that frameshift sites have arisen within genes during the recent history of Euplotes, and that it may be an ongoing process. Overall, the data suggest to us that the appearance of a frameshift site in a Euplotes gene is selectively neutral, or near-neutral. This would require an efficient mechanism of frameshifting in Euplotes. A model will be presented linking frequent frameshifting to a second unusual genetic feature of Euplotes, stop codon reassignment.

Notes: Control of protozoal pathogens in water and food destined for human use employs chemical and physical agents for inactivation of trophozoites and cysts. γ radiation, when given in certain doses, damages DNA as well as other cell components. Previously, we characterized damage in irradiated Giardia lamblia trophozoites by using Nomarski interference and scanning electron microscopy. To further examine cellular damage, irradiated trophozoites were viewed with transmission electron microscopy. Degranulation of cytoplasm at higher irradiation doses was observed, however, axonemes, adhesive discs, and peripheral vesicles appeared morphologically similar in treated as well as control cells. In order to determine damage to the DNA, the comet assay was employed. The comet assay is a single cell gel electrophoresis assay that measures the number of single and double strand breaks in DNA. This was achieved by embedment of live cells in low melting point agarose, lysis of cells, and then addition of an alkali solution to allow the DNA to unwind. After ample time for unwinding, the cells were electrophoresed, thus pulling the smaller broken strands away from the supercoiled DNA. We used Sybr GreenR, a DNA specific fluorescent dye, and a signal-enhancing camera to visualize the DNA. Lengths of comet tails (corresponding to number of strand breaks) were measured for quantification of damage.

Notes: Karenia brevis (Davis) is a unicellular dinoflagellate responsible for nearly annual “red tides” in the Gulf of Mexico. Insight into the molecular mechanisms that control growth, toxicity, and adaptive mechanisms in K. brevis is critical to understanding the formation and persistence of these toxic blooms. However, little information is available on the molecular biology K. brevis. Therefore, we constructed a cDNA library from which to gain insight into its expressed genome and to develop tools for studying gene expression. Large-scale sequencing of 9728 clones yielded 7001 high-quality expressed sequence tags (ESTs) for further analysis. The highest expressed gene accounts for only 1% of the total ESTs. Approximately 29% of ESTs were found to have homology to known sequences in other organisms after BLASTx similarity comparisons to the Genbank nonredundant database (p〈10−4). Using a minimum identity of 95% within a 50-bp region of overlap, the 7001 ESTs were assembled into 5054 contigs. Of the 5054 contigs, 4399 contained only a single sequence. Of those containing 〉2 ESTs, approximately 40% displayed single nucleotide polymorphisms, suggesting the presence of multiple gene copies in this haploid organism. Gene-specific 60-mer oligonucleotides were then designed for each of the 5054 contigs using a Parcel clustering package, version 2.2.8 (Agilent). The resulting oligonucleotides and controls were printed on glass slides to yield an 8000 feature array using inkjet printing technology (Agilent). The 8000 features included 5054 unique features and 2946 secondary probes. Validation experiments to assess system noise, reproducibility, log ratio accuracy, and differential gene expression are underway using Agilent Feature Extraction tools and Rosetta Luminator Gene Expression Analysis software.

Notes: Apostome ciliates are exclusively symbionts, typically of crustaceans. Their life cycles are complex, but show remarkable similarities to ophyroglenines and to other symbiotic oligohymenophoreans, particularly those that undergo microstome–macrostome transformations. The highly modified structures around the cytostome—the rosette and x, y, and z kineties—have made the assessment of homologies to other groups of ciliates difficult. A description of the apostome somatic kinetids with well-developed overlapping kinetodesmal fibrils suggested affinities with hymenostomes (Bradbury 1966. J. Protozool., 13:591). Further analysis of the ultrastructural features of the oral region of the tomite of Hyalophysa demonstrated homologies to the paroral and adoral ciliature of hymenostomes, confirming these affinities (Bradbury 1989. J. Protozool., 36:95). To test this hypothesis, we proposed to sequence the small subunit rRNA (SSrRNA) genes of apostomes. Specimens of Gymnodinioides sp. were collected from molts of the amphipod Marinogammarus obtusatus collected off the coast of Eastport, ME. Seawater was decanted from the substrate upon which tomonts had settled, and the dish was flooded with 70% ethanol. The ethanol-fixed ciliates were collected by a micropipette, rinsed with distilled water, and DNA was extracted using the modified Chelex® protocol. The SSrRNA genes were amplified by PCR, and sequences obtained in both directions. Initial BLAST searches of the GenBank databases clearly demonstrated affinities with oligohymenophorean ciliates, particularly scuticociliates. In preliminary phylogenetic analyses which use likelihood, distance and parsimony methods, this relationship was confirmed. However, the apostome sequence diverged basal to the Subclasses Astomatia and Scuticociliatia consistent with the assignment of a Subclass Apostomatia within the Class Oligohymenophorea. We have made collections of Hyalophysa chattoni and anticipate that the SSrRNA gene sequences of this genus will confirm the relationship of apostomes to the oligohymenophoreans.Funded by NSERC Canada Discovery Grant to D. H. L.

Notes: Our laboratory studies how the contractile cytoskeleton contributes to the process of phagocytosis. Because of its larger size and ease of manipulation, we chose the macrostomal cell of Tetrahymena vorax as our model for analysis of the distribution of proteins of prominent filamentous structures within the large oral apparatus (OA). Previous work in our laboratory identified centrin as a component of the fine filamentous reticulum (FFR) and actin and tetrin as colocalizing components of the coarse filamentous reticulum (CFR) and cross-connectives (CC) (J. Eukaryot. Microbiol., 51:253–257). Our new data also show that actin coimmunoprecipitates with tetrin proteins, confirming our actin–tetrin colocalization results. Because of its positioning around the cytostome, the actin-containing CFR/CC is a logical candidate for involvement in phagosome “pinch-off” following prey ingestion. We have analyzed this process by employing an assay that uses the addition of calcium to induce phagosome formation. We show that inhibitors of actin are able to block this event, indicating that actin is necessary for phagosome “pinch-off”. The OA also contains precisely arranged arrays of microtubules. We have examined the spatial relationship of the microtubular arrays to the distribution patterns of centrin, actin and tetrin, and found that tubulin and centrin fluorescences overlap in the region of the undulating membrane (UM). Tubulin fluorescence overlaps with actin and tetrin labeling at the inner edge of the CFR, where the CFR and UM converge. In addition to ciliary and oral rib labeling, tubulin antibodies also recognize the outer microtubule bundle (OMB), which delineates the right and posterior boundary of the OA.

Notes: This mini-review examines the maximum growth rate and threshold levels (the food level where growth rate is zero) of marine planktonic ciliates and heterotrophic dinoflagellates. There are strong indications that ciliates will out-compete dinoflagellates, as they have higher maximum growth rates, lower threshold levels and are able to rapidly exploit both harmful and non-harmful dinoflagellates as prey. I suggest that ciliates are neither the tortoise (slow and steady) nor the hare (fast and foolish), but the best combination of both. To some extent, this argument is raised as a “straw-man” to be knocked down by discussion; the session is intended to serve as a platform for evaluating the relative importance of ciliates and heterotrophic dinoflagellates in marine ecosystems.

Notes: A modified Pechini method was used to prepare undoped and doped La0.67Ca0.33MnO3 (LCMO) with homogeneous compositions and uniform fine powders. The variations of the lattice parameters and cell volumes of doped LCMO are attributed to the effect of ionic size and the creation of the oxygen vacancy. The effect of Ba2+ on the magnetic and conduction properties of LCMO is mainly related to the enhancement of the Mn3+–O–Mn4+ bond angle. The occupation of Al ions in Mn sites and the creation of the oxygen vacancies lead to an increase of the resistivity and a decrease of Tc and Ms. The variable-range hopping model with p=1/4 and ρ0 independent of temperature was found to be the best fit for undoped and doped LCMO, shown in 〈link href="#f4"/〉. It is suggested that T0 is mainly the measure of the extent of the disorder. For Al3+-doped LCMO, the small-polaron mechanism was found to be dominant in the temperature range from 300 to 350 K, and the evaluated values of the activation energy are about 0.22 eV and independent of the Al concentration. Low-field magnetoresistance (LFMR) was found to be enhanced by Ba doping but diminished by Al doping. The segregation of Al ions to the grain-boundary region may play a significant role in the intent to form a one-slope field-dependent MR response. The mechanisms of MR response of doped LCMO were suggested. 〈figure xml:id="f4"〉4〈mediaResource alt="image" href="urn:x-wiley:00027820:JACE00610:JACE_00610_f4"/〉 Resistivity as a function of temperature showing that the best fit was the variable-range hopping model with p=1/4 and ρ0 independent of temperature for (a) La0.67(Ca1−xBax)0.33MnO3 in the temperature range from 300 to 430 K, (b) La0.67Ca0.33(Mn1−yAly)O3 in the temperature range from 260 K to Tc, and the small-polaron mechanism (ρ=CT exp (Ea/kT) for (c) La0.67Ca0.33(Mn1−yAly)O3, in the temperature range from 300 to 350 K.

Notes: Transparent glass ceramics containing CaF2 nano-crystals co-doped with Er–Yb were developed by heat treatment of glasses in the system SiO2–Al2O3–CaF2–LnF3 (Ln=Er, Yb). The crystal size of CaF2 increased with increasing heat-treatment temperature. Upconversion emission intensities at 660 and 540 nm increased dramatically with increasing heat-treatment temperature. The cathode luminescence mapping indicates that the visible Er-luminescence arises mainly from the precipitated CaF2 nano-crystals with a phonon energy lower than that of a silicate matrix. It is concluded that both Er and Yb were concentrated in the CaF2 nano-crystals, and the quantum efficiency of Er3+-luminescence and the energy transfer efficiency from Yb3+ were considerably improved after ceramization.

Notes: Titania microtube arrays were fabricated by replication of human hair. The microtube is nanoporous in its wall and has nanoporous platelets on its outer surface, which were derived from cuticle cells on hair surface. The wall thickness of titania microtubes could be controlled by adjusting the number of sol–gel cycles applied. The nanopores acted as an effective nanoreactor where Au nanoparticles were in situ synthesized. The microchannels, nanopores, and noble metal nanoparticles may provide a unique combination that would be attractive in such applications as catalysis, adsorption, and separation.

Notes: Tantalum(V) nitride, prepared by nitridation of nanosized Ta2O5 at 800°C for 8 h under ammonia flow, was thermally decomposed to cubic nanocrystalline TaN at a temperature of 1000°C for 3 h under argon atmosphere. The resulting powders have been characterized using X-ray diffraction (XRD) and transmission electron microscopy. XRD-pure cubic TaN nanoparticles with a diameter of 50–100 nm can be obtained by the process. The decomposition process was found to depend on the temperature. Mechanisms that account for the decomposition of Tantalum(V) nitride are discussed. The results indicate that the method can permit formation of cubic-phase Tantalum(III) nitride under ambient pressure and moderate temperatures.

Notes: E-glass fibers were coated with a 15CaO–15BaO–20SiO2–50TiO2 thin film by the sol–gel method. Mechanical and chemical tests were performed on coated and uncoated fibers in cement and cement extract solutions to investigate the interactions between cement and gel-glass film. The results show that the resistance of E-glass fibers to the alkali cement medium is enhanced by the 15CaO–15BaO–20SiO2–50TiO2 coating. The significant roles of TiO2, CaO, and BaO in the protection fibers from the alkaline attack of cement are described. Some evidence is presented that the alkali corrosion of the coated fibers results in the formation of a thick and compact Ti film that suppresses further corrosion reaction.

Notes: The sinterabilities of fine zirconia powders including 5 mass% Y2O3 were investigated, with emphasis on the effect of Al2O3 at the initial sintering stage. The shrinkage of powder compact was measured under constant rates of heating (CRH). The powder compact including a small amount of Al2O3 increased the densification rate with elevating temperature. The activation energies at the initial stage of sintering were determined by analyzing the densification curves. The activation energy of powder compact including Al2O3 was lower than that of a powder compact without Al2O3. The diffusion mechanisms at the initial sintering stage were determined using the new analytical equation applied for CRH techniques. This analysis exhibited that Al2O3 included in a powder compact changed the diffusion mechanism from grain boundary to volume diffusions (VD). Therefore, it is concluded that the effect of Al2O3 enhanced the densification rate because of decrease in the activation energy of VD at the initial sintering stage.

Notes: Crack-healing behavior of silicon carbide ceramics sintered with AlN and Sc2O3 has been studied as a function of heat-treatment temperature and applied stress. Results showed that heat treatment in air could significantly increase the indentation strength whether a stress is applied or not. After heat treatment with no applied stress at 1300°C for 1 h in air, the indentation strength of the specimen with an indentation crack of ∼100 μm (≈2c) recovered its strength fully at room temperature. In addition, a simple heat treatment at 1200°C for 5 h under an applied stress of 200 MPa in air resulted in a complete recovery of the unindented strength at the healing temperature. However, higher applied stress led to fracture of the specimens during heat treatment. The static fatigue limit of the specimens crack healed at 1200°C for 5 h under 200 MPa was ∼450 MPa at the healing temperature. The ratio of the static fatigue limit of the crack-healed specimen to the unindented strength was ∼80%.

Notes: Tetracalcium phosphate (TTCP) Ca4(PO4)2O is one of the major powder components of self-setting orthopedic and dental cements. Traditionally, TTCP powders are produced by a solid-state process by soaking Ca- and P-containing precursors between 1350° and 1500°C. Such procedures require expensive high-temperature furnaces and subsequent grinding of sintered particulates. Grinding not only introduces contamination but alters the structure of TTCP, thereby reducing its bioactivity. The present paper offers a lower temperature synthesis process for TTCP with several interesting features. First, the synthesis procedure used Ca(CH3COO)2·H2O and NH4H2PO4 as separate sources for Ca and P, respectively. Second, the reactants underwent multiple melting and decomposition stages, thus increasing the reactivity of the synthesis process. NH4H2PO4 melted at 190°C and engulfed the calcium acetate particles. The Ca-acetate component decomposed into CaCO3 at around 400°C while still surrounded by the molten phosphate liquid and an amorphous Ca-metaphosphate phase. Hydroxyapatite, Ca10(PO4)6(OH)2 (HA), and β-Ca3(PO4)2 crystallized upon heating the powder mixture to 700°C. Slightly above 1200°C, the TTCP phase was formed. This sequence of reactions led to a process temperature of 1230°C, the lowest temperature ever reported for the synthesis of TTCP. Third, the resulting powders required much less grinding, which itself is advantageous. Fourth, the resulting powders were in situ seeded with HA. HA-seeded TTCP powders were tested for their apatite-inducing ability by soaking them in synthetic body fluid at 37°C. TTCP powders of this study were readily covered with carbonated apatitic calcium phosphates within the first 72 h.

Notes: The effect of microstructure on the sliding-wear properties has been studied in two types of pressureless liquid-phase-sintered (LPS) SiC ceramics, one with coarse, in situ-grown elongated grains and the other with fine, equiaxed grains. Elongated-grain LPS SiC has been found to have dramatically improved sliding-wear properties over equiaxed-grain LPS SiC, which has been attributed to the interlocking network of elongated SiC grains. The introduction of an interlocking network of elongated grains represents a new guideline for the microstructural design of polycrystalline ceramics that are both sliding-wear resistant and toughened.

Notes: Microwave dielectric properties of polycrystalline Ca5Ta2TiO12 ceramics have been tailored using different glass additives. Several glasses such as B2O3, SiO2, B2O3–SiO2, ZnO–B2O3, Al2O3–SiO2, Al2O3–B2O3–SiO2, BaO–B2O3–SiO2, MgO–B2O3–SiO2, ZnO–B2O3–SiO2, PbO–B2O3–SiO2, and 2MgO–Al2O3–5SiO2 were added to calcined Ca5Ta2TiO12 powder in different weight percentages. Among these glasses, addition of 0.1 wt% of SiO2, Al2O3–SiO2, Al2O3–B2O3–SiO2, MgO–B2O3–SiO2, and 2MgO–Al2O3–5SiO2 improved the microwave dielectric properties. Fluxing of Ca5Ta2TiO12 with 0.1 wt% of 2MgO–Al2O3–5SiO2 glass has ɛr=39, Qu×f〉40 000 at 5 GHz and τf=+8 ppm/°C. Near-zero τf was obtained with the addition of glasses like Al2O3–SiO2, Al2O3–B2O3–SiO2, MgO–B2O3–SiO2, and 2MgO–Al2O3–5SiO2. Addition of all the glasses except BaO–B2O3–SiO2 reduced the τf of Ca5Ta2TiO12 ceramics. Two weight percent glass addition to Ca5Ta2TiO12 ceramics reduced their sintering temperature down to 1450°C from 1625°C and τf close to zero but deteriorated the ɛr and unloaded quality factor. The effects of glass content on the structure and microstructure of Ca5Ta2TiO12 ceramics were studied by X-ray diffraction and scanning electron microscopic techniques.

Notes: Neutron diffraction data of α-sialon and complementary phases were collected on the neutron powder diffraction (NPD) diffractometer installed in the NFL Studsvik, at a wavelength of 1.470 Å. Calculations were carried out by using the FullProf 2000 utilizing the crystal structure of the yttrium α-sialon phase. Selected profile and structure parameters were refined in the calculations. The calculated data showed that either La or Nd were also present in the α-sialon crystal structure in the presence of Y. The comparison of the present phases' weight contents, which were determined by the qualitative phase analysis between NPD and X-ray diffraction data, was carried out.

Notes: A series of [0.8Pb(Ni1/3Nb2/3)O3–0.2PbTiO3]/[(Ni0.2Cu0.2 Zn0.6)Fe2O4] (PNNT/NiCuZn) ferroelectric–ferromagnetic composites were prepared by the conventional solid-state route. The composites show good co-firing behaviors. X-ray diffraction and scanning electron microscope studies confirmed the coexistence of ferroelectric PNNT phase and ferromagnetic NiCuZn phase in the composites. No significant chemical interaction has occurred between PNNT phase and NiCuZn phase. All sintered samples exhibit typical magnetic hysteresis loops at room temperature. The saturation magnetization of composites rises linearly with the increase in NiCuZn content. Frequency dependence of initial permeability was also measured. With an increase in NiCuZn, the initial permeability increases and the cutoff frequency tends to decrease. The Maxwell–Garnett (MG) effective medium theory was used to model the magnetic properties of composites. Although the MG equation cannot give an accurate prediction for the initial permeability of composites because of the oversimplified assumption, it gives upper and lower limits for the initial permeability of compositions.

Notes: Bioresorbable and functionally graded apatites (fg-HAp) ceramics, which are characterized by gradations in crystallinity and the grain size of hydroxyapatite (HAp:Ca10(PO4)6(OH)2), were designed using bovine bone by the calcination and partial dissolution–precipitation method. The fg-HAp ceramics had macropores of 100–600 μm originated from spongy bone, and micropores of 10–160 nm. Fg-HAp ceramics loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2/fg-HAp) were implanted into the subcutaneous tissue of rats. Eight weeks after the implantation, the surface and bulk degradations of the fg-HAp-containing body fluid occured, and small pieces of fg-HAp were incorporated into the induced bone and fatty marrow, suggesting that osteoinduction occurred in conjunction with bone remodeling. The rhBMP-2/fg-HAp ceramics developed could become a resorbable biomimetic material with fast bioresorption and osteoinduction characteristics.

Notes: A hydrothermally treated zirconia colloid was introduced during the precipitation of hydroxyapatite (HAP) to achieve an HAP–zirconia nanocomposite. High dispersion of zirconia was achieved at zirconia loadings below 8 wt%. Vickers hardness was optimized with a 1.5 wt% loading of zirconia. A low loading (1.5 wt%) of tetragonal zirconia was able to increase the bending strength of nanocrystalline HAP from 183 to 243 MPa. This HAP–zirconia nanocomposite was sintered to full density by 1000°C under an applied load of 50 MPa. The average grain sizes of HAP and zirconia were maintained at ≤100 nm. With the high strength and low loading of secondary phase, these HAP-based nanocomposites should be attractive for orthopedic and dental implant applications.

Notes: The effect of iron and iron/yttrium codoping on the densification and grain growth of ultra high-purity (99.995%) fine-grained alumina has been studied. The experiments were carried out under both oxidizing (flowing air) and reducing conditions (N2/H2 mixture, pO2∼5.1 × 10−14). For studies carried out in air, relative to undoped alumina, the addition of 1000 ppm Fe was found to reduce the densification rate by a factor of 5 and also retard the grain growth rate. This result, which was consistent with tensile creep data obtained in a separate study, was attributed to the retardation of grain-boundary diffusive processes by segregating Fe(III) ions. In contrast, under reducing conditions the 1000 ppm Fe- doped samples exhibited an increase in the densification rate of 2.5 orders of magnitude over that of the undoped samples. In the case of the codoped compositions (1000 ppm Fe/1000 ppm Y), for heat treatment in air, the densification behavior did not differ significantly from that of samples singly doped with Y (1000 ppm). However, under reducing conditions, the presence of the Fe2+ in the samples appeared to compensate for the retarding effect of the yttrium, such that the densification rate of the codoped samples was comparable with that of the undoped material. A mechanism based on compensating point defects is invoked to rationalize the more rapid kinetics under reducing conditions.

Notes: The phase composition, microstructure, and electrical resistivity of hot-pressed AlN ceramics with 0–4.8 wt% Sm2O3 additive were investigated. The phase composition was approximately consistent with that estimated from the Sm2O3–Al2O3 phase diagram using the amount of added Sm2O3 and oxygen content of the AlN raw material. When sintered at more than 1800°C, the AlN ceramics with 1.0–2.9 wt% Sm2O3 additive contained an Sm-β-alumina phase wetting the grain boundaries, and their electrical resistivity considerably decreased to 1010–1012Ω·cm. This resistivity decrease was caused by the continuity of the Sm-β-alumina phase with a resistivity lower than that of bulk AlN.

Notes: Thin fibrils (usually 20–100 nm in diameter) of ferroelectric PbZr0.52Ti0.48O3 have a preferred nucleation and growth in the [001] direction in small particles. X-ray diffraction with the X-ray beam facing the fibril surfaces, which lie along the [001] direction, thus involves reflections of manifested intensity from (100) and (010) planes. No reflection occurs from the perpendicular planes to the [001] fibrils. A transmission electron micrograph with the corresponding electron diffraction from fibrils confers the results of the preferred growth. The fibrils have a modified orthorhombic crystal structure of lattice parameters a=0.4038 nm, b=0.4017 nm, and c=04148 nm, with an enhanced 8.033 g/cm3 density over 8.006 g/cm3 in the usual tetragonal structure of a=0.4036 nm and c=04146 nm. Surface anisotropy in a fibril that imposes (and drives) a shear stress over growing crystallites (within the fibril) along the [001] surface favors this specific crystal structure in them according to the precursor structure. A single-phase sample is obtained in 2 h by heating of an amorphous template of precursor (of the metal cations with a polymer of polyvinyl alcohol and sucrose) at 500°–800°C in air.

Notes: The reaction-bonded aluminum oxide (RBAO) process utilizes the oxidation of intensely milled aluminum/alumina powder compacts that are heat treated in air to make alumina-based ceramics. RBAO samples are typically oxidized in a furnace which is heated at 1°C/min to 1100°C. Heat-treating samples with a characteristic dimension 〉1 mm, without adjusting the furnace temperature program, usually results in a cracked ceramic. Cracking is caused by the excessive thermal and chemical stresses that result from steep temperature gradients (〉30°C/mm) and compositional gradients (〉5000 mol·(m3·mm)−1), which develop under the deleterious ignition and shrinking core reaction regimes. While adjustments to the furnace temperature program based on continuum models have had some success, the use of feedback-controlled firing is investigated as a means to avoid the furnace temperature program design step and to decrease the firing time. Feedback-controlled firing is shown to improve yields and significantly reduce the time required to completely oxidize the aluminum. For example, a 16 g sample with a characteristic dimension of 7.56 mm, which previously took 〉100 h to oxidize completely, was successfully oxidized crack free in 18.3 h using feedback control. Using the typical heat-treatment cycle, a 1 mm sample was fired in 18 h. With feedback-controlled firing, the same sized sample was fired in only 5 h.

Notes: Qualitative residual stresses in current environmental barrier coatings (EBCs) were inferred from the curvature of EBC-coated SiC wafers, and the effects of EBC stresses on the durability of EBC-coated SiC were evaluated. The magnitude of substrate curvature correlated fairly well with the EBC–SiC coefficient of thermal expansion (CTE) mismatch, EBC modulus, and thermally induced physical changes in EBC. BSAS (1−xBaO·xSrO·Al2O3·2SiO2, 0≤x≤1) components in the current EBCs, i.e., Si/mullite or mullite+BSAS/BSAS or yttria-stabilized zirconia (YSZ: ZrO2–8 wt% Y2O3), were the most beneficial for reducing the EBC stress in as-sprayed as well as in post-exposure EBCs. The reduced stress was attributed to the low modulus of BSAS. The addition of a YSZ top coat significantly increased the substrate curvature because of its high CTE and sintering in thermal exposures. There were clear correlations between the wafer curvature and the EBC durability. The Si/mullite+20 wt% BSAS/BSAS EBC maintained excellent adherence, protecting the SiC substrate from oxidation, while the Si/mullite+20 wt% BSAS/YSZ EBC suffered delamination, leading to severe oxidation of the SiC substrate, after a 100 h −1300°C exposure in a high-pressure burner rig.

Notes: In endemic areas, clinical manifestations of Plasmodium falciparum infection range from asymptomatic parasitaemia to life-threatening severe syndromes. Immune differences that could account for this disparity are poorly understood. Using tight criteria to classify patients into non-overlapping clinical categories, we showed that cerebral malaria and severe anaemia were distinct immunological syndromes and that a proper quantitative description of cytokine profiles in the various clinical groups is essential to the understanding of the activation of immunocompetent cells.Due to the limited size of paediatric blood samples, we chose to measure cytokine mRNA using real-time RT-PCR. We showed that RT efficiency displayed intra-and intergenic variations that have to be taken into consideration for reliable absolute RNA quantification when comparing clinical cases. We thus developed a SYBR Green I-based real-time RT-PCR method using synthetic external RNA standards specific for each gene. Absolute RNA quantification is achieved by reverse transcribing known copy numbers of this RNA standard in parallel with cellular RNA. Strictly specific primers were designed to allow the quantification of any RNA in the same thermocycling parameters for future automation. Our method gave similar results for a lower cost when compared with TaqMan, and led to reproducible and reliable absolute RNA quantification. We validated it in vitro on naïve PBMC stimulated by LPS and ex vivo on PBMC from malaria patients. This new method raises the unprecedented possibility to compare cytokine mRNA levels between different clinical groups and is a powerful tool to further study the inflammation processes associated to malaria.

Notes: Intestinal microsporidiosis caused by Enterocytozoon bieneusi and Encephalitozoon intestinalis are opportunistic infections occurring in severely immuno-depressed patients, and may cause severe chronic diarrhea. Due to the extent of the HIV pandemic, microsporidia could pose a serious threat to public health in Africa. This study was conducted in Libreville, Gabon, central Africa, among HIV-positive patients between September 2002 and December 2003. Criteria for inclusion were being HIV positive (HIV1 and/or HIV2), regardless of the CD4 cell count, stage of the disease or gastrointestinal symptoms. Nine hundred and ninety-tree stool samples from 836 patients (mean age 38 years, range 18 months-74 years) were screened for microsporidia by immunofluorescence using species-specific monoclonal antibodies and confirmed by PCR. Twenty seven cases of E. bieneusi infection were found in the cohort, a prevalence of 2.7%. These patients were in the most severely immuno-depressed group, 84% had a CD4 cell count below 200/mm3 compared to 57% of the cohort (mean=55 CD4+cells/mm3 compared to a mean of 88/mm3 for the microsporidia negative patients with less than 200 CD4/mm3).The ribosomal DNA ITS sequence has been determined for several E. bieneusi isolates. A very high diversity of genotypes wasfound: eight different sequences were found from only 12 samples. This is surprisingly high since in previous studies conducted in Europe and America only 15 of the 49 E. bieneusi genotypes described have been found to infect humans. Only three genotypes from our samples have already been described: type K (two specimens). previously reported in human and cat, type D (one specimen) in human, pig and rhesus monkey, type E (1 specimen) in man, pig, racoon and muskrat. The five other genotypes are new and have been named Gabon-1 to 5. The phylogenetic analysis of the sequences shows that genotypes Gabon-1,2,3 and 4 (one specimen each) are close to types E, WL12, D and K, respectively, which belong to a group comprising most genotypes described so far. However, the Gabon-5 genotype (four specimens) is only distantly related to this group and is most apparent to the group of genotypes (WL1-3) recently described from racoons in North America. It was thus suggested that this group could represent another species or subspecies of E. bieneusi which are host-adapted and do not infect humans. However, the finding of genotype Gabon-5 shows that even distantly related genotypes infect severely immuno-depressed humans.This work was supported by the French National Agency for AIDS Research (ANRS-1264).

Notes: While the Plasmodium falciparum fully annotated genome has now been released, functional analysis of its expected about 5300 genes remains to be carried out to understand their roles during the parasite development, in particular for about 60% of genes devoid of significant similarities in other species. Here, a suppression subtractive hybridisation (SSH) screen was used to identify genes coding for proteins expressed during merozoite morphogenesis. The resulting library yielded clones with cDNA inserts ranging from a few hundreds to about a thousand base pairs. We report here the analysis of 50 independent cDNA clones and of the corresponding 40 P. falciparum genes. While 27.5% of them turned out to be previously described genes, all known to code for proteins expressed in schizont/merozoite stages (EBA-175, MSP-1, MSP-3, MSP-6, ABRA/MSP-9, coronin, myosin A and the CLAG/RhopH1 protein), the remaining 72.5% were “putative” and “hypothetical” genes, coding for a variety of proteins among which we found several protease orthologs and orthologs of cytoskeleton-associated and/or actin-interacting proteins such as dynamin and formin-2 as well as other rhoptry proteins. In addition to providing experimental evidence for their expression in schizont/merozoite stages, we discuss how these genes represent original candidates to investigate the molecular events required to elaborate infective merozoites.

Notes: This paper reports on the analysis of the microstructure of precursor-derived ceramics by plasma etching and field emission scanning electron microscopy. By applying this technique, the nano-crystals in Si–C–N-based ceramics and composites can be clearly observed without difficulty.

Notes: Approximately 85 million gallons of high-level waste (HLW) is currently stored in underground tanks at the Hanford Reservation and the Savannah River Site (SRS). The waste consists of a hydroxide-rich precipitate (sludge) and a sodium-rich supernate. The supernate is a NaOH rich solution containing lesser amounts of NaNO3 and NaNO2 and small amounts of soluble fission products, cladding materials, and organics (volatile organics and semi-volatile organics known as VOCs and SVOCs). The Department of Energy (DOE) has chosen glass as its waste form for both sludge and sodium-rich supernate. However, because of the volume of the supernate, alternatives to vitrification are being sought for some of this waste. One alternative is to remove 137Cs and 90Sr from the supernate. Decontaminating the waste in this way allows the waste to be designated as low-activity waste (LAW) and as such the waste now becomes eligible for solidification and disposal on site. SRS is solidifying its LAW with a blended Portland cement forming Saltstone. Hanford has been considering a bulk vitrification process in which the LAW will be mixed with Hanford soil and vitrified in place in a disposable carbon-arc powered glass melter/waste container. Both waste forms can then be buried on site in appropriate vaults or low-level waste land fills. A hydroceramic is an alternative waste form designed to solidify and stabilize LAW that is made from metakaolin plus NaOH and/or NaOH rich LAW supernate. In addition to NaOH, LAW can contain a wide range of sodium nitrate and sodium nitrite concentrations. Although a hydroceramic waste form can be made directly from some types of decontaminated waste, e.g., those that are highly alkaline (8–12M NaOH) and contain less than 25 mol% of NOx (NOx is used as the short-note for nitrates and nitrites in this article.) relative to the total Na in the waste, by simply mixing the LAW with metakaolin and curing the resulting paste at 90°C, the remaining LAW, especially that stored at Hanford must be pretreated in some way before it can be similarly solidified; the relative molar proportion of NOx/Na must be reduced to 25% or less. In this paper calcination is evaluated as a potential pretreatment method for Hanford AN-107 (AN-107 is a waste storage tank on Hanford site) LAW, but in choosing this method it is necessary to divide the preparation of the hydroceramic waste form into two steps: denitration/denitrition of the liquid waste stream to produce a granular calcine followed by solidification using a metakaolin plus 4M NaOH binder. A simulated Hanford AN-107 LAW was calcined at 375°, 450°, 525°, 600°, and 675°C in the presence of sucrose and metakaolin added as a calcination aid. It was shown that the leachability of the calcines decreased as calcination temperature increased, i.e., the waste form became more crystalline. In the second step, each of the granular calcines was mixed with additional metakaolin and just enough 4M NaOH to form a thick paste. The paste was precured at 40°C and then autoclaved at 90°C to form a monolith. X-ray diffraction and scanning electron microscopy characterization showed that the calcines themselves contained an amorphous phase and crystalline hydroxysodalite, and that the hydroceramics made from these calcines plus additional metakaolin/NaOH binder consisted predominantly of zeolite A and hydroxysodalite. The temperature used to prepare the calcines not only affected the properties of the calcines, but those of the monolithic hydroceramics as well. Experimental results demonstrated that 525°C represented the optimal temperature for producing the most suitable calcine for subsequent solidification with metakaolin and 4M NaOH. The resulting hydroceramic nuclear waste form was strong and had the lowest overall leachability. The leachability of the hydroceramic is normally lower than that of the corresponding calcines up to ∼600°C. The product consistency test (PCT) determined normalized release rate NRNa for the hydroceramic (0.14 g/m2·day) was comparable to similar leach rates determined for Hanford's low-activity waste reference material glass (0.08 g/m2·day) and a steam reformed calcine made with Hanford's AN-107 tank waste (0.25 g/m2·day).

Notes: Electrical conduction properties of undoped and 1 mol% Sr-doped LaP3O9 glasses and glass–ceramics were investigated over the temperature range of 673–1123 K. Both the materials showed relatively low conductivities in the glassy state. However, the conductivity of the Sr-doped LaP3O9 glass significantly increased with a heat treatment above the crystallization temperature, while the conductivity of the undoped LaP3O9 glass did not improve even after the heat treatment. It was concluded that crystallization of the Sr-doped LaP3O9 glass induced protonic conduction and thus enhanced the conductivity. Electrical conduction properties of the Sr-doped LaP3O9 glass–ceramic fundamentally resembled those of the sintered crystalline Sr-doped LaP3O9.

Notes: The phases formed in the ternary system (Na1/2Bi1/2)TiO3–Bi4Ti3O12–BaTiO3 (NBT–BTO–BT) were studied at 1150°C in air. A very accurate picture of the ternary phase diagram was obtained examining almost 90 different compositions, exploiting low-angle XRD analyses to study the layer compounds. New compounds with five perovskite blocks (m=5) were discovered deep in the phase diagram. No compounds with m〉5 were found. It was also established that pure perovskite compounds can be obtained only at compositions very close to the NBT–BT line. The relationships between the phases is discussed and it is hypothesized that the number of perovskite blocks in the system is determined by charged sites being created by the progressive substitution of Bi3+ in the A site of the perovskite blocks of BTO with the A cations of the perovskite end-member.

Notes: Channeled yttria-stabilized cubic phase of the zirconia (Ni–YSZ) cermets are produced by reduction of laser-assisted directionally solidified NiO–YSZ lamellar eutectics. The material is formed by ∼400 nm wide alternating lamellae of 40% porous Ni and YSZ, which serve as parallel channels for gas flow and electronic transport and for oxygen ion diffusion. The low-energy interfaces formed between the metallic Ni particles and the YSZ prevent particle coarsening and impart long-term stability to the anode at operating temperatures. The electrical conductivity and the pore size distribution present no degradation after 300 h at 900°C under a H2/N2 atmosphere. This stability is indicative of an improvement in comparison with conventional Ni–YSZ anodes for solid oxide fuel cells.

Notes: A sol–gel synthesis method based on the diol route is reported here for the fabrication of strontium bismuth tantalate (SBT, SrBi2Ta2O9) ferroelectric thin films. A tantalum penta-glycolate (TPG)-based sol is synthesized, which is air stable and has low toxicity. The structure of the TPG compound is studied by nuclear magnetic resonance (NMR) spectrometry, and the results show that TPG contains a tantalum cation bonded to five diol groups. The molecular association of the TPG derivatives in the sol, through the terminal hydroxyl groups of the diol ligands, is responsible for its transformation into a gel. Other metal compounds can be easily added to the TPG-based sols for the preparation of air-stable and precipitate-free multicomponent solutions. These solutions are precursors of complex oxide materials. In this paper, SBT thin films have been prepared by this sol–gel method. These films develop a layered perovskite structure after crystallization. The films have a remanent polarization of Pr∼10 μC/cm2, a coercive field of Ec∼65 kV/cm, and are fatigue free up to ∼1010 cycles.

Notes: Dy-α-sialon and β-Si3N4 materials containing Dy-oxynitride glass were hot pressed at 1800°C for 1 h. The luminescence spectra of Dy3+ in these samples were compared when excited at 350 nm. The results showed that two strong emission bands in the region 470–500 nm and 570-600 nm, associated with the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+ ions, were observed in Dy-α-sialon. However, no emission peak was detected from the β-Si3N4 sample, despite it containing the same amount of Dy3+ cations. This proved that only the Dy3+ cations in the α-sialon structure, not those in the oxynitride glass, produce the luminescence spectrum.

Notes: By lamination of silicon nitride tapes, components with complex geometries can be produced. Unstructured tapes can be laminated by common thermal compression. Structured tapes, however, have to be joined by pressureless processes using e.g. pastes as lamination aids because deformation of the structures would occur. These pastes usually contain a binder for maintaining the mechanical contact between the tapes during processing. To prevent the high mass loss of typical organic binders during burnout, pre-ceramic polymers were used in this work. These ceramic precursors convert partly into an inorganic material during heat treatment with a significant reduced mass loss compared with common organic binders. Thus, the porosity in the interlayer of a laminated stack is strongly decreased, which should be favorable for the mechanical and thermal properties. This work discusses the resulting microstructure, strength, and thermal diffusivity data of stacks laminated with pastes containing various precursor contents. These results are compared with those obtained by samples prepared by compression of green tapes. It is found that except for some large pores, the microstructure of the precursor-derived interlayers is qualitatively the same as in the tape material. For stacks made by both lamination methods, strength measurements reveal that the properties parallel and perpendicular to the layers are different. It is shown that the same strength level can be obtained both by using the pressureless route and by the compression method. Unlike the strength, the thermal conductivity does not change with the direction of measurement.

Notes: A method based on the use of four piezoelectric resonances for three sample geometries that allows obtaining the full set of linear electric, mechanical, and electromechanical coefficients, and all related losses of a piezoelectric ceramic has been applied to Mn-doped 0.655Pb(Mg1/3Nb2/3)O3–0.345PbTiO3 at the morphotropic phase boundary (MPB PMN–PT). Length-poled MPB PMN–PT ceramic plates presented piezoelectric shear double resonances associated with a thickness gradient of tetragonal and rhombohedral (or monoclinic) phases that originated during poling. The versatility of the method still allowed addressing these double resonances and obtaining all the linear coefficients and losses of the well-poled material. These are given for MPB PMN–PT and compared with those of a Navy type II Pb(Zr,Ti)O3 (PZT) ceramic. MPB PMN–PT presents piezoelectric coefficients as high as soft PZT but significantly lower losses, and so less overheating and hysteresis under high driving fields. Its thermal stability has been studied up to 100°C, and the temperature dependence of a number of linear coefficients and of the thickness and planar coupling factors and frequency constants of disks has been obtained. The latter thickness parameters hardly changed with temperature, while planar ones showed a relative variation of 10%.

Notes: Nanocrystalline titanium nitride (TiN) particles were directly synthesized in an atmospheric microwave plasma torch, using gas-phase titanium tetrachloride (TiCl4), with N2 and H2 as reactants. The gas-phase TiCl4 was injected with H2 gas into the microwave plasma-torch flame generated by N2 swirl gas, and then the dark blue powders were deposited on the inner wall of the quartz tube. The synthesized powder samples were analyzed by scanning electron microscopy (SEM), SEM-EDX, X-ray diffractometer (XRD), transmission electron microscopy, and FT-Raman. The average crystallite sizes of TiN measured from XRD patterns decreased from 15.5 to 11.6 nm, as the flow rate of H2 injected into the microwave plasma torch increased from 0.03 to 0.3 liters per minute.

Notes: Addition of fructose has been shown to reduce the viscosity of aqueous suspensions of nanometric alumina powders. Highly concentrated and flowable aqueous nanometric alumina suspensions were achieved by fructose addition. Oxygen-17 nuclear magnetic resonance spectroscopy was used to investigate the relaxation time and the molecular mobility of water in the suspensions with and without fructose. It was found that a significant fraction of water is bound to the surface with lower mobility. Average water mobility increases and the viscosity of the suspension decreases with fructose addition, both of which are because of displacement of water from the alumina surface by fructose molecules. The results were related to rheological behavior of the suspensions.

Notes: Cracks situated parallel to, and very near, the interface in layered, ductile-brittle composite specimens were investigated with finite-element analysis. Elastic, plastic and thermal properties previously obtained from experiments were utilized in the model. A routine was employed for automatic crack extension and remeshing, enabling simulation of incremental crack propagation. The elastic, thermal and plastic contributions to crack propagation behavior were investigated, along with the variation of these with crack length and crack-tip position. Thermal residual stresses are shown to have a large influence on crack path, although this is mitigated to some extent by plasticity. The implications on the inherent reliability of joints and layered materials containing brittle constituents are discussed.

Notes: Processing effects on the dielectric properties of sol–gel-derived PbZrO3–PbTiO3 (PZT) films integrated onto Pt/Ti/SiO2//Si substrates are reported. Sol–gel synthesis and deposition conditions were designed to produce films of varying thickness (95–500 nm) with consistent chemical composition (Pb (Zr0.53Ti0.47)O3), phase content (perovskite), grain size (∼110 nm), crystallographic orientation (nominally (111) fiber textured), and measured residual stress. The Stoney method, using laser reflectance to determine wafer curvature, derived biaxial tensile stress values of 150 and 180 MPa for PZT films after a baseline correction for electrode interactions during thermal processing was employed. The PZT films were of high dielectric quality, with low losses and negligible dispersion. Calculated values of dielectric constant (K̄′) were found to decrease from 960 to 600 with decreasing film thickness. A series-capacitor model successfully recovered a room-temperature K1′ for the PZT (1,170) in good agreement with bulk reports but was unable to reproduce the expected dielectric anomaly near 380°C. This discrepancy and the resulting diffuse phase transformation were attributed to the biaxial tensile stress present in the PZT films.

Notes: The piezoelectric effect in ferroelectric single crystals and ceramics is investigated considering intrinsic (lattice), and extrinsic (originating mainly from displacement of domain walls) contributions. The focus of the study of intrinsic properties is on piezoelectric anisotropy, which was examined using the Landau–Ginsburg–Devonshire phenomenological theory. It is shown that the enhanced piezoelectric response along nonpolar directions, observed in many perovskite systems, is a consequence of the flattening of the Gibbs free energy profile. This flattening is common for temperature-, composition-, and external field-induced enhancement of the piezoelectric properties along nonpolar axes. A brief review of recent advances in understanding the origins of the piezoelectric nonlinearity, hysteresis, and frequency dispersion is also given.

Notes: Carbon nanotube (CNT)-dispersed Si3N4 ceramics with electrical conductivity were developed based on the lower temperature densification technique, in which the key point is the addition of both TiO2 and AlN as well as Y2O3 and Al2O3 as sintering aids. This new ceramic with a small amount of CNTs exhibits very high electrical conductivity in addition to high strength and toughness. Since Si3N4 ceramics with Y2O3–Al2O3–TiO2–AlN were originally used as a wear material, electrically conductive Si3N4 ceramics are expected to be applied for high-performance static-electricity-free bearings for aerospace and other high-performance components.

Notes: Monotonic and cyclic fatigue behavior of single fibers or fiber fabrics are of significant interest, since fiber assemblies or fiber-reinforced composite materials in structural applications are often subjected to cyclic loading. Studying the cyclic fatigue behavior of fibers is particularly difficult because of their small diameter (∼10 μm) and high aspect ratio. In this paper, we report results of monotonic tension and tension–tension fatigue behavior of two sol–gel-derived ceramic fibers: Al2O3–SiO2–B2O3 (Nextel 312) and Al2O3 (Nextel 610). Nextel 312 exhibited a great deal of variability in tensile strength, reflected by a Weibull modulus of 4.6, versus Nextel 610, which had a Weibull modulus of 10.5. Our experiments showed clearly that cyclic loading was more damaging than static loading and, thus, resulted in a lower cyclic fatigue life compared with static loading. The fracture behavior under fatigue loading was distinctly different from that under monotonic loading. It is believed that processing-induced flaws acted as crack initiation sites, and that the cyclic loading induced subcritical cracking, followed by coalescence of cracks immediately prior to failure.

Notes: This paper presents the applicability of a simple and novel technique based on capillary suction time (CST) to characterize the dispersibility of suspension. The method is simple, rapid, and requires little experience. It has been shown to be extremely useful for comparing the dispersibility during preparation of a stable suspension of ceramic powder with high solids loading. The method has also been found to be suitable for obtaining homogeneous suspensions of maximum stability. The dispersibility of particles in any suspension has been assessed with respect to the condition at point of zero charge (pHpzc). A quantitative measure of the dispersibility has been proposed in term of a dispersion ratio (DR). According to this proposition, the suspension is in a state of dispersion when the value of DR is more than unity, whereas it is in a flocculated state when the value of DR is less than unity.