Space-Charge Distribution across Internal Interfaces in Electroceramics Using Electron Holography: II, Doped Grain Boundaries

Transmission high-energy electron holography has been utilized to quantitatively determine the magnitude, sign, and spatial extent of the electrical potential, electric field, as well as the charge and stress field distributions across electrically active grain boundaries (GBs) in polycrystalline SrTiO₃. The polycrystalline compacts utilized were bulk-doped with Fe and GB-doped with Mn, which is diffused into them under a nonequilibrium situation. The holography results reveal negatively charged GBs with associated positive space-charge, indicating that Mn resides as an acceptor dopant on the Ti site, creating a negative bound charge at the GBs. A large heterogeneity in the electrical activity is observed among various GBs; while some GBs show high Schottky barriers, others have very small barriers. The distribution of the bound charge and the compensating free charge, which together contribute to the formation of GB charge and space-charge, has been estimated. The bound charge experiences an outward stress field due to the force of the electric field on either side of the GB. The height of the double Schottky barrier, the Debye length, as well as the spatial extent of the bound charge and space-charge at the GB are derived from these holography results. The results also provide a quantitative measure of the defect densities as well as of the contribution of the electrostatic stress field to the lattice relaxation at the GBs and yield a point defect model for the GB.     

Concretes and mortars recycled with water treatment sludge and construction and demolition rubble

There are about 7500 water treatment plants in Brazil. The wastes these plants generate in their decantation tanks and filters are discharged directly into the same brooks and rivers that supply water for treatment. Another serious environmental problem is the unregulated disposal of construction and demolition rubble, which increases the expenditure of public resources by degrading the urban environment and contributing to aggravate flooding and the proliferation of vectors harmful to public health. In this study, an evaluation was made of the possibility of recycling water treatment sludge in construction and demolition waste recycling plants. The axial compressive strength and water absorption of concretes and mortars produced with the exclusive and joint addition of these two types of waste was also determined. The ecoefficiency of this recycling was evaluated by determining the concentration of aluminum in the leached extract resulting from the solubilization of the recycled products. The production of concretes and mortars with the joint addition of water treatment sludge and recycled concrete rubble aggregates proved to be a viable recycling alternative from the standpoint of axial compression strength, modulus of elasticity, water absorption and tensile strength by the Brazilian test method.     

Obesity among offspring of women with type 1 diabetes

OBJECTIVE: To determine subsequent growth and body composition of children born to women with type 1 diabetes compared with controls. DESIGN: Prospective cohort study. SETTING: Follow-up of offspring born to women with type 1 diabetes and controls from an earlier study of diabetes and lactation. SUBJECTS: Seventeen nondiabetic offspring of women with type 1 diabetes and 18 offspring of control women (age range 5.9 to 9.0 years). OUTCOME MEASURES: Anthropometric measures at follow-up included height, weight, triceps and subscapular skinfold thickness. Information on usual nutrient intakes and physical activity patterns was elicited through questionnaires. Body composition was determined from skinfold thickness measures and bioelectrical impedance analysis. A child was identified as obese if he or she met at least 2 of the following 4 criteria for obesity: (1) weight-for-height equal to or greater than 120% of the National Center for Health Statistics (NCHS) reference median plus triceps skinfold greater than the 85th percentile; (2) body mass index (BMI) greater than the 95th percentile for age and sex; (3) percent body fat (from impedance measures) equal to or greater than 25 for boys and 30 for girls; or (4) percent body fat (from sum of skinfold measures) equal to or greater than 25 for boys and 30 for girls. RESULTS: There were 7 obese children in the type 1 diabetes group and none in the control group (p = 0.007). Obese children did not differ from nonobese children in birth weight, body fat patterning, nutrient intake, physical activity patterns, maternal pregravid weight or blood glucose control during the last trimester of pregnancy. Mothers of obese children, however, had fewer years of education and gained more weight during pregnancy compared with mothers of nonobese children in the type 1 diabetes group (p < 0.05). CONCLUSION: Obesity during childhood is a significant problem among nondiabetic children of women with type 1 diabetes. The association of childhood obesity with lower maternal education and excessive pregnancy weight gain warrants further investigation.     

Aging and immunoglobulin isotype patterns in oral tolerance

The haptic perceptual sybsystem of dynamic touch is prominent in manipulating and transporting objects, providing a nonvisible awareness of their linear dimensions. The hypothesis that perceptions of object width and height by dynamic touch are different functions of the inertia tensor is addressed. In two experiments heights and widths of nonvisible wielded objects were judged separately. Experiment 1 used solid rectangular parallelepipeds of different sizes; Experiment 2 used objects of identical mass and linear dimensions but nonidentical inertia ellipsoids. Width and height perceptions of comparable reliability and accuracy were found to vary as distinct functions of the objects' inertial eigenvalues. Discussion focused on the notion of tangible shape and on the selectivity of attention within dynamic touch.     

Corrosion effects of glass on YSZ electrolytes

This work reports on the microstructure and electrical properties of different yttria stabilized zirconia (YSZ) based cells using: (i) intimate mixtures of YSZ and a commercial soda-lime glass (up to 20 wt%), sintered at different temperatures; (ii) YSZ disks covered with a layer of glass on one side and fired in a clean laboratory furnace for two hours at different temperatures (1250–1350 °C); (iii) YSZ pellets exposed to the exhaust gases of one (industrial) glass melting furnace, at temperatures around 1300 °C. Microstructural observations and impedance spectroscopy measurements were used to demonstrate the potential of the latter technique in monitoring the electrolyte corrosion. The high-and intermediate-frequency impedance arcs showed a significant and coherent dependence on the progress of corrosion, due to the formation of glass–ceramic composites with large glass/ceramic interfaces. Similar results were obtained with laboratory scale and industrial experiments. EDS analysis showed an higher concentration of Y₂O₃ in the intergrain region and a corresponding concentration decrease in the electrolyte grains.     

The validity of verbal autopsies for assessing the causes of institutional maternal death

We investigated the patterns of degenerative changes of indoleamine-accumulating cells (IACs) induced by 5,7-dihydroxytryptamine (5,7-DHT, 100 microg), and the glial reaction to the neurodegenerative changes of IACs in the cat retina by using light-and electron-microscopy. The neurons accumulating 5,7-DHT in the cat retina were a few ganglion cells and displaced amacrine cells located in the ganglion cell layer (GCL), and some amacrine cells in the inner nuclear layer (INL). The cell density (per unit area, 1 mm2) of the 5,7-DHT accumulating cells in the GCL and INL was 910 and 134 cells, respectively. Most 5,7-DHT accumulating cells showed dark degeneration characterized by widening of the cellular organelles at early stage, and by darkening of the cytoplasm at a late stage. In addition, amacrine cells, showing a typical filamentous degeneration, were observed in a few cases. The degenerated neurons were phagocytosed by microglial cells and astrocytes. The immunoreactivity for glial fibrillary acidic protein (GFAP) in Muller cells was increased at early stage, but thereafter abruptly decreased. In a few cases, severe degenerative changes were observed in Miller cells. These results indicate that 5,7-DHT induces severe dark degeneration of IACs, and most degenerated cells could be eliminated by microglial cells and astrocytes in the cat retina.     

Synthesis and characterization of manganese oxide-doped dicalcium silicates obtained from rice hull ash

This work describes the synthesis and hydration behavior of dicalcium silicates doped with manganese. The syntheses were performed using silica obtained from rice hull ash. The solids (SiO₂, CaO and MnO) were weighed in stoichiometric proportions to prepare silicates having a ratio (Ca + Mn)/Si = 2. Insertion of manganese varied from 1 to 10% (mol). Solids were grounded and water was added rendering aqueous suspensions. The suspensions were sonicated for 60 min in an ultrasonic bath. After drying, the resulting solids were grounded and burned at 800 °C. The preparation of calcium silicates containing up to 10% of manganese oxide was observed.Hydration degree of a dicalcium silicate and calcium silicate containing 5% of manganese was determined by thermal analysis. Both materials present similar behavior. Hydration degree reaches approximately 70% after 60 days.     

Linear driving force approximation in cyclic adsorption processes: Simple results from system dynamics based on frequency response analysis

The linear driving force (LDF) approximation for cyclic adsorptive processes is discussed on the basis of model equivalence with the homogeneous diffusion model (HDM), the pore diffusion model (PDM) and the intraparticle diffusion and convection model (IDCM). Model equivalence is based on the frequency response of the adsorbent particle, namely on the equality of the amplitude ratio and the phase-lag functions. The analysis of the continuous stirred tank adsorber (CSTA) and of the plug flow adsorber (PFA) is addressed.     

Plasters and renders for salt laden substrates

The EU project COMPASS, Compatibility of Plasters and renders with Salt loaded Substrates in historic buildings, aimed at improving the maintenance of monuments by means of a better understanding of the working principles of the plasters and the damage mechanisms induced by salt crystallisation. Salt damage was effectively studied modelling the moisture and salt transport and degradation (irreversible dilation) and a fast and efficacious salt crystallisation test developed. Practical results were the assessment of the requirements for plasters to be used on salt loaded substrates and guidelines for selecting plasters suitable for different situations. The dissemination of the results was also entrusted to the expert system MDDS.