Study of Structural and Electrical Properties of Conventional Furnace and Microwave-Sintered BaZr0.10Ti0.90O3 Ceramics

Structural, dielectric, piezoelectric, and ferroelectric properties of Zirconium-doped barium titanate (BaZr_0.10Ti_0.90O₃) ceramics prepared by microwave (MWS) and conventional (CS) sintering process are compared. X-ray diffraction and Raman spectroscopy indicate clearly the structural changes and confirm the effective diffusion of zirconium with the MWS technique to form BZT. Scanning electron microscopy reveals a fine grain, and a dense microstructure in the MWS ceramics processed under 4 h of cycle time (including heating, cooling, and holding time) in comparison with CS requiring 22 h. At room temperature the microwave sintered samples exhibit improved electrical properties exhibiting higher resistivity, higher dielectric constant, a lower dielectric loss, and a reduced dependence on frequency. Impedance and electric modulus spectroscopy analysis in the frequency range (40 Hz–1 MHz) and high-temperature range (573–873 K) suggests two relaxation processes attributed to bulk and grain boundary effects in the impedance plots for the both MWS and CS ceramics. The microwave-sintered BZT ceramics are found to be more attractive for room temperature device applications with improved properties, however, at higher temperatures they tend to degrade in comparison with the CS ceramics.     

Studies on optimization of parameters for dewatering of ground calcite-rich ore

This paper deals with filtration of very-fine size ground brecciated calcitic limestone ore slurry using flocculant chemicals. Screening of flocculants was carried out using capillary suction time (CST). Optimization of the neutral slurry filtration behaviour was carried out using a commercial non-ionic type polyacrylamide based synthetic flocculant. Response surface methodology and central composite rotatable design was used for model development and optimization of the filtration process. Critical filtration parameters such as applied vacuum, cake thickness and flocculant dosage were optimized. A correlation coefficient of 0.97 was obtained both for filtration rate and percent cake moisture. The analysis of variance of the determined model indicated that linear effects, interaction effects, quadratic effects, linear terms of all the three variables and some interaction among them are more significant for the filtration rate and cake moisture percent. The optimum filtration rate of 742 kg/(h m²) was obtained at the optimum conditions with cake moisture of 22.3%.     

Mapping and monitoring of degraded lands in part of Jaunpur district of Uttar Pradesh using temporal spaceborne multispectral data

Apart from soil erosion by wind and water, the major land degradation processes operating in irrigated commands in arid and semi-arid regions are waterlogging and subsequent salinization/alkalinization. Remote sensing data have been used successfully in studies of the spatial extent, magnitude and temporal behaviour of lands affected by such processes. In this work we interpreted Landsat Multispectral Scanner images acquired during 1975 and Landsat Thematic Mapper data acquired during 1993, in conjunction with ancillary information and adequate ground data, to derive information on the extent and spatial distribution of various degraded lands, namely salt-affected soils, waterlogged areas and eroded lands in part of the Jaunpur district of Uttar Pradesh. The results indicate a significant shrinkage in the spatial extent of salt-affected soils (of the order of 49.76%) over the period 1975 to 1993. A similar trend was observed in the temporal behaviour of waterlogged areas, but an increase (6.45%) was found in the spatial extent of eroded lands. The methodology employed and the observations made are described here in detail.     

Image transforms as a tool for the study of soil salinity and alkalinity dynamics

Principal components analysis (PCA), ratioing, image differencing and intensity-hue-saturation (IHS) transformation have been widely used in monitoring various natural resources and environmental hazards. In our study, the temporal behaviour of salt-affected soils in the Indo-Gangetic alluvial plains of Uttar Pradesh has been studied using Landsat MSS data for 1975 and 1992. Apart from routine digital classification of temporal MSS data using Guassian maximum likelihood algorithm, PCA, image differencing, and ratioing were also evaluated for their potential in bringing out temporal changes in salt-affected soils, if any. The results indicate that the third principle component, image differencing, and ratioing of the first two MSS bands for two periods have brought out substantial information associated with the temporal behaviour of saltaffected soils.     

Process parametric study for the recovery of very-fine size uranium values on super-conducting high gradient magnetic separator

This paper discusses the application of super-conducting high gradient magnetic separator for the recovery of very-fine size uranium bearing mineral values present in the flotation tailings of an Indian copper ore. The U₃O₈ content of the tailings is 0.009%. The focus of this study is centered on determining the effect of various process variables like applied magnetic field, wool filling factor in the canister, wool diameter, loading capacity of the matrix, feed flow-rate and slurry pH on the recovery of uranium values in the magnetized matrix. The results indicate significant improvement in the recovery of <10 μm size uranium bearing particles, to the extent of 60–65% in SCHGMS as against mere 20% in other high intensity magnetic separators. The enrichment ratio of U₃O₈ values in the magnetic fraction was in the range of 2.2–2.5 only due to interference from other magnetic minerals.     

Transition metal modified bulk BiFeO3 with improved magnetization and linear magneto-electric coupling

At present BiFeO₃ (BFO) is the most attractive and sole example, which possesses low magnetization value, high leakage current and low polarization in ceramic form. Single-phase room temperature multiferroics are rare in nature. This paper deals with the improved magnetic and observed linear magneto-electric coupling in Co and Sm co-doped BiFeO₃ ceramics synthesized by sol-gel process at low temperature ∼600 °C. As synthesized Bi_0.9Sm_0.10Fe_0.95Co_0.05O₃ (BSFCO) showed high impurities phases (20%) over wide range of calcination temperatures. Impurity phases reduced drastically from 20% to 5% after leaching with nitric acid. However the electrical and the magnetic properties were almost the same for both phases. Well-defined magnetic hysteresis with high magnetic moment was found at room temperature. Ferroelectric polarization studies demonstrated similar values and shape as reported in literature for the pure bulk BFO. Linear magneto-electric (ME) coupling and weak ME coefficient (α) ∼ 0.6 e−10 s m⁻¹ were observed in the co-doped BFO. The origin of the strong ferromagnetic property in our samples may be due to the presence of rare earth and transition metal ions at the lattice sites of BFO or due to impurity phase, since we have not seen any change in magnetization with reduction of impurity phase the later effect is more unlikely.     

Spontaneous hemobilia in a hemophiliac treated by factor VIII replacement and nasobiliary drainage

We report a case of spontaneous hemobilia in a hemophilia patient presenting with classical Sandblom's triad of symptoms. Endoscopic retrograde cholangiography was helpful in establishing the diagnosis. Hemobilia subsided with factor VIII replacement and endoscopic nasobiliary drainage. Endoscopic nasobiliary drainage resulted in lysis of the clots in the biliary tree and relief of obstructive jaundice.     

Thermal Compatibility and Durability of Wearing Surfaces on GFRP Bridge Decks

The paper investigates thermal compatibility between wearing surface (WS) materials and glass fiber reinforced polymer (GFRP) bridge decks, and proposes a more durable hybrid WS system for GFRP decks. Wearing surface delamination problems observed on many existing GFRP bridge decks motivated the investigation and the search for a durable WS material that could alleviate the problems. Several WS materials were bonded to GFRP panels, with and without surface preparation, and tested under various environmental conditions. In addition to the standard ASTM C884 method, the testing program included two new methods for thermal compatibility testing to reflect the in-service conditions of WSs on GFRP bridge decks. The proposed methods were developed to account for the influence of freeze–thaw–heat and submerge–freeze cycles on thermal compatibility and durability. The investigation concluded that a hybrid WS system, consisting of two-layered WS materials, has the best bond quality. Applied directly on top of a GFRP deck, the top layer of the hybrid WS system had the best tire resistance, forming a nonskid riding surface.     

Ritz-Based Static Analysis Method for Fiber Reinforced Plastic Rib Core Skew Bridge Superstructure

A Ritz-based static analysis procedure is described for fiber-reinforced plastic, skew bridge superstructure, or deck, with a parallel grid core. This is a simplified analysis method based on a transformed plate formulation and the classical Ritz method. The rib core bridge superstructure, or deck, is idealized as a homogeneous, orthotropic skew plate to which the Ritz method is applied to discretize the resultant, equivalent orthotropic skew plate. Three laminated skew plate examples are presented; the results are compared with finite-element solution to verify the validity of the simplified method. A practical demonstration of a rib core skew bridge superstructure is investigated using the simplified method. The procedure provides a useful analysis tool that can be used in the preliminary design stage without the use of finite-element analysis.     

Primary Neuron/Astrocyte Co‐Culture on Polyelectrolyte Multilayer Films: A Template for Studying Astrocyte‐Mediated Oxidative Stress in Neurons

We engineered patterned co‐cultures of primary neurons and astrocytes on polyelectrolyte multilayer (PEM) films without the aid of adhesive proteins/ligands to study the oxidative stress mediated by astrocytes on neuronal cells. A number of studies have explored engineering co‐culture of neurons and astrocytes predominantly using cell lines rather than primary cells owing to the difficulties involved in attaching primary cells onto synthetic surfaces. To our knowledge this is the first demonstration of patterned co‐culture of primary neurons and astrocytes for studying neuronal metabolism. In our study, we used synthetic polymers, namely poly(diallyldimethylammoniumchloride) (PDAC) and sulfonated poly(styrene) (SPS) as the polycation and polyanion, respectively, to build the multilayers. Primary neurons attached and spread preferentially on SPS surfaces, while primary astrocytes attached to both SPS and PDAC surfaces. SPS patterns were formed on PEM surfaces, either by microcontact printing SPS onto PDAC surfaces or vice‐versa, to obtain patterns of primary neurons and patterned co‐cultures of primary neurons and astrocytes. We further used the patterned co‐culture system to study the neuronal response to elevated levels of free fatty acids as compared to the response in separated monoculture by measuring the level of reactive oxygen species (ROS; a widely accepted marker of oxidative stress). The elevation in the ROS levels was observed to occur earlier in the patterned co‐culture system than in the separated monoculture system. The results suggest that this technique may provide a useful tool for engineering neuronal co‐culture systems, that may more accurately capture neuronal function and metabolism, and thus could be used to obtain valuable insights into neuronal cell function and perhaps even the pathogenesis of neurodegenerative diseases.