Preparation and Kinetic Considerations for the Dissolution of Cr‐substituted Iron Oxides in Reductive‐complexing Formulations

The dissolution rate coefficients of Cr‐substituted (0‐20 at.% Cr) iron oxides viz. hematite and magnetite were determined by using an inverse cubic rate (ICR) law applicable for spherical particles as well as by a general kinetic equation (GKE) applicable for polydispersed particles. An attempt is made to compare both the treatments for different kinds of dissolution profiles obtained by employing oxides with narrow particle size distribution in V(II)‐EDTA and citric acid‐EDTA‐ascorbic acid formulations at 353±5K. The dissolution profiles could be classified into three types based on the nature of oxide and formulations. It is observed that both ICR and GKE treat the dissolution course as a function of decrease in fraction of undissolved mass, m/m₀. The dissolution rate coefficients determined by ICR and GKE have shown the similar trend of decrease with increasing Cr content of the oxides and was ascribed to lattice stabilization.     

Analysis of unsteady flow of blood conveying iron oxide nanoparticles on melting surface due to free convection using Casson model

Iron oxide nanoparticles have great importance in future biomedical applications because of their intrinsic properties, such as low toxicity, colloidal stability, and surface engineering capability. So, blood containing iron oxide nanoparticles are used in biomedical sciences as contrast agents following intravenous administration. The current problem deals with an analysis of the melting heat transfer of blood consisting iron nanoparticles in the existence of free convection. The principal equations of the problem are extremely nonlinear partial differential equations which transmute into a set of nonlinear ordinary differential equations by applying proper similarity transformations. The acquired similarity equalities are then solved numerically by Runge‐Kutta Felhsberg 45th‐order method. The results acquired are on the same level with past available results. Some noteworthy findings of the study are: the rate of heat transfer increases as the Casson parameter increases and also found that the temperature of the blood can be controlled by increasing or decreasing the Prandtl number. Hence, we conclude that flow and heat transfer of blood have significant clinical importance during the stages where the blood flow needs to be checked (surgery) and the heat transfer rate must be controlled (therapy).     

Structural,electrical and electrochemical behaviours of LiNi0·4 M 0·1Mn1·5O4 (M = Al,Bi) as cathode material for Li-ion batteries

In order to improve the cycling performance of LiMn₂O₄ based cathode materials, we have synthesized a new composition, LiNi_0·4 M _0·1Mn_1·5O₄ (M = Al, Bi), by the sol–gel method. The formation of solid solutions is confirmed by structural characterization using TG/DTA, XRD, FT–IR, EPR, SEM and EPR. A.c.-impedance (Nyquist plot) showed a high frequency semicircle and a sloping line in the low-frequency region. The semicircle is ascribed to the Li-ion migration through the interface from the surface layer of the particles to the electrolyte. Cyclic voltammogram (between 3·5 and 4·9 V) for these materials using CR2032 coin-type cell shows two pairs of redox peaks corresponding to two-step reversible intercalation process, wherein Li-ions occupy two different tetragonal 8a sites in spinel Li _x Mn₂O₄ (x < 1) lattice. The galvanostatic charge/discharge curves for M = Al (77 mAh g^–1) showed reasonably good capacity retention than that of M = Bi (11 mAh g^–1) at the end of 17th cycle.     

Coastal geomorphological and land‐use and land‐cover study of Sagar Island,Bay of Bengal (India) using remotely sensed data

Morphological changes on Sagar Island are occurring at an alarming rate due to both natural and anthropogenic activities. The eastern part of the island is rapidly eroding due to destabilization and growth of tidal flats in the Muriganga estuary and the gradual shifting of water current towards the island. Over the last four years (1996–1999), the rate of coastal erosion has been much higher (11.35 km²) than accretion (2.65 km²), compared with the conditions prior to 1996. Coastal places like Dublat, Basantpur, Gobindapur, Collectorganj, and Sumatinagar have become the critical zones of erosion. The shorelines along the eastern and south‐western sides are receding. The extent of coverage of the paddy field, sandy beaches, and land vegetation has decreased from 1996 to 1999 by 15.7, 1.1, and 3.5 km², respectively. An integrated database of the island was generated using spatial and non‐spatial data collected through field survey, satellite images of IRS‐1C LISS III, and topomaps. Spatial data include coastal geomorphological landforms, land‐use and land cover, shoreline change, sandy beaches, coastal erosion sites, agricultural fields, aquaculture sites, and coastal riparian vegetations. Non‐spatial data include the demography and evolution of the island. The main critical environmental issues of the island are: (1) degradation of mangrove forests and coastal erosion; (2) overpopulation and over‐exploitation of living resources; and (3) destruction of seawalls. Further degradation may lead to extinction of a variety of species and scarcity of marine food unless properly managed and regulated.     

Enhanced dissolution of hematite in reductive-complexing formulation under regenerative mode

The citric acid-EDTA-ascorbic acid (CEA) formulation used for the dissolution of hematite (α-Fe₂O₃) powder results in a major portion of the dissolved iron as Fe(III)-EDTA (∼80%). Since Fe(III)-EDTA does not dissociate on the cation-exchange resin due to its high stability, the on-line regeneration of EDTA during the dissolution process becomes difficult. The results reported in this study show how, in such a situation, regeneration of EDTA is made possible by introducing carbon steel coupons of known surface area in the dissolution formulation. In these powder dissolution studies, we demonstrate the enhanced dissolution of α-Fe₂O₃ (more than the stoichiometric amount) in dilute CEA formulation by adopting a regenerative mode of dissolution. The powder dissolution study reported in this work is to simulate the application of dilute chemical formulation for the chemical decontamination of a system wherein the base metal (stainless-steel)-aided dissolution is absent e.g., primary system of BWRs/PWRs. A typical case study evaluation is carried out to estimate the approximate surface area of carbon steel required to be exposed in the real system application.     

Synthesis,structural, magnetic and NO2 gas sensing property of CuO nanoparticles

Cupric oxide (CuO) nanoparticles are synthesized by the oxidation of Cu/Cu₂O, which is obtained by the chemical reduction of Cu²⁺ ions with ascorbic acid. XRD pattern confirmed the formation of CuO, and FE-SEM image shows the clusters consisting of 25–30 nm sized particles. The band gap energy (3.7 eV) from optical absorption spectra is blue shifted to that of bulk values. The Néel temperature, T_N ≈ 230 K for paramagnetic to antiferromagnetic transition was clearly seen. The magnetic hysteresis loops at 5 K showed weak ferromagnetic behavior. Based on the dc electrical conductivity (300–500 K), the apparent activation energy was 0.36 eV. The NO₂ gas sensing property of CuO was reasonably good in the temperature range of 200–300 °C, and the sensitivity increased with an increase in gas concentration but the effect of temperature is marginal.     

Functional characteristics of gelatin extracted from skin and bone of Tiger-toothed croaker (Otolithes ruber) and Pink perch (Nemipterus japonicus)

The utilization of waste from fish processing industry for production of value added products has attracted substantial attention. Tiger-toothed croaker (Otolithes ruber) and Pink perch (Nemipterus japonicus) are used for surimi production and have the potential of abundant supply of raw skins and bones. In order to evaluate the waste from Tiger-toothed croaker and Pink perch as a source of gelatin, the gelatin was extracted from skin and bones and its rheological and functional properties were examined. The skins of Tiger-toothed croaker and Pink perch yielded 7.56% and 5.57% gelatin, whereas their bones yielded 4.57% and 3.55% respectively indicating skin as an important source for gelatin production. The gel strength of gelatins from the skins and bones of Tiger-toothed croaker (170 g and 140 g respectively) were found higher than Pink perch skin and bone gelatins (150 g and 130 g respectively). Similarly, the viscosity, melting point, emulsifying capacity and stability, foaming capacity and stability, and water holding capacity of gelatin extracted from Tiger-toothed croaker were in general greater than those of the gelatin from Pink perch and the values of skin gelatin were higher compared to bone gelatin in both the species. Hydroxyproline contents in skin and bone of Tiger-toothed croaker were 7.77 and 7.51 mg/g and in Pink perch they were 7.63 and 7.41 mg/g respectively. It can be concluded from the present study that Tiger-toothed croaker skin is a prospective source to produce gelatin in good yield with desirable functional properties comparable to commercially available mammalian gelatins.     

Rubber Seed Oil - The Untapped Potential Source in Karnataka,India

Rubber seeds constitute 25 to 30 per cent good fatty oil which is used as a major raw material in the manufacture of soaps. Karnataka with 7000 hectares of rubber plantation area and about 13 lakh trees is so far untapped for its seeds. It is expected to yield 660 tons of seeds during the current year and 1290 tons by 1984–85. The seeds collected from various rubber plantation divisions were extracted for oil and the oils were analysed for their fatty acid composition by gas liquid chromatography.     

Scalable multirobot planning for informed spatial sampling

This paper presents a distributed scalable multi-robot planning algorithm for informed sampling of quasistatic spatials fields. We address the problem of efficient data collection using multiple autonomous vehicles and consider the effects of communication between multiple robots, acting independently, on the overall sampling performance of the team. We focus on the distributed sampling problem where the robots operate independent of their teammates, but have the ability to communicate their current state to other neighbors within a fixed communication range. Our proposed approach is scalable and adaptive to various environmental scenarios, changing robot team configurations, and runs in real-time, which are important features for many real-world applications. We compare the performance of our proposed algorithm to baseline strategies through simulated experiments that utilize models derived from both synthetic and field deployment data. The results show that our sampling algorithm is efficient even when robots in the team are operating with a limited communication range, thus demonstrating the scalability of our method in sampling large-scale environments.

     

Synthesis and magnetic studies of nano-crystalline GdFeO3

Nano-crystalline GdFeO₃ was synthesized by three different soft-chemical routes viz. hydrothermal, co-precipitation and combustion. The hydrothermal and co-precipitation methods resulted in amorphous powder which on further heating resulted in GdFeO₃. The combustion method produced phase pure GdFeO₃ in a single step. The particle size was in the range of 50-70 nm as calculated by Scherrer's formula. The transmission electron micrographs (TEM) showed the presence of fairly regular particles. Magnetic studies revealed a paramagnetic behavior. The magnetic susceptibility (in emu/g-Oe) of GdFeO₃ samples as synthesized by hydrothermal, co-precipitation and combustion routes was found to be 9.6 × 10^− 5, 6.7 × 10^− 5 and 4.4 × 10^− 5 respectively.