Effect of Al substitution on the magnetization reversal and complex magnetic properties of NiCr2O4 ceramics.

A series of polycrystalline NiCr2-xAlxO4 (0.1 ≤ x ≤ 0.25) spinel ceramics have been synthesized using a sol-gel method. DC magnetization measurements are carried out at different temperatures and magnetic fields. A novel magnetization reversal has been observed in the field cooling process for the x = 0.2 sample, which can be ascribed to the competition between two magnetic sublattices due to their different temperature dependences. The magnetic interaction evolution, related to the complex magnetic properties, is revealed by exchange constants that have been estimated according to ferrimagnetic Curie-Weiss fitting and mean field theory. The fitting result confirmed the evolution of antiferromagnetic and ferromagnetic components with Al substitution, which is supported by the observations from the isothermal magnetization measurements. The positive and negative values of the magnetic moment can be utilized for storage applications based on the results of magnetic switching effect measurements.

Negative magnetization, complex magnetic ordering and applications of Cr-doped Co2TiO4.

Polycrystalline Co2Ti1-xCrxO4 (0 ≤ x ≤ 0.2) inverse spinel ceramics have been synthesized via a sol-gel technique. The dc magnetization measurement in the field-cooled mode shows that negative magnetization could be observed until x reaches 0.2. The exchange constants are calculated using the ferrimagnetic Curie-Weiss fitting and the mean-field theory. This reveals that the strength of the inter sublattice magnetic interaction presents a non-monotonic trend with the increase in Cr content and reaches the minimum at x = 0.1, giving rise to the highest compensation temperature in the x = 0.1 sample. The applicability of the x = 0.1 sample is investigated in light of two prominent magnetic effects: (i) the stable magnetic switching effect indicates the potential applications in magnetic switching and data storage and (ii) the coexistence of normal and inverse magnetocaloric effects suggests a potential application in a constant temperature bath at 54 K.

Maximum-entropy principle: ecological organization and evolution.

In the present paper, we have first studied the role of the maximum-entropy principle to explain the concept of organization of a physical system in the decreasing law of entropy with the increase of external constraints imposed on the system. We have then considered an open ecosystem (living) and determined a quantitative measure of ecological organization from the consideration of the thermodynamics of irreversible processes. Finally, we have tried to explain the evolution of the ecosystem in the light of Prigogine's principle of "order through fluctuation."

Assessing the uranium DGT-available fraction in model solutions.

The uranium speciation in humic acid (HA) and fulvic acid (FA) model solutions was investigated by diffusive gradients in thin films (DGT). A reference solution was used to normalize the DGT data from different samples. This approach was used to assess uranium DGT-available fraction (FU), which was calculated from experimental data and reflect both the mobility and lability of uranium species. FU decreased with increasing HA or FA concentrations, because more uranium was able to bind the strong binding sites of HA or FA. When copper was spiked, FU increased due to the competition between copper and uranium. In HA model solutions, an increase of ionic strength could increase FU, and when pH was greater than 7, FU increased significantly. The DGT uptake factor (φ), which can be obtained from data fitting, is the ratio of the product of diffusion coefficient and lability degree of the unknown sample to that of the reference solution. In U-HA-NaHCO3 solutions, UO2(CO3)22- had a relatively high φ value and might be the most DGT-available species. This approach allows the comparison of DGT data from different samples, and combining with a data fitting procedure, it can be used to investigate the distribution of metal species.

High prevalence of metabolic syndrome and its correlates in two tribal populations of India and the impact of urbanization.

BACKGROUND AND OBJECTIVES: Metabolic syndrome is one of the major causes of morbidity and mortality in the world. The prevalence of this syndrome is high among Asians, including Indians, and is rising, particularly with the adoption of a modernized life style. Whether traditional societies in India have a low prevalence and the extent to which a transition to a modern life style contributes to the increase in prevalence are unknown. To examine the role of environmental and genetic factors in metabolic syndrome we conducted a study in two sub-Himalayan tribal populations with shared ancestry (Toto and Bhutia). The Toto live exclusively in a rural area, whereas a section of the Bhutia has adopted a modern life style. METHODS: Fasting (12 h) blood samples of Toto (n=258); rural Bhutia (n=75) and urban Bhutia (n=230) were collected, with written informed consent. Lipid profile, blood pressures, body fat and other anthropometric parameters were assessed. Criteria suggested by National Cholesterol Education Programme (NCEP) Adult Treatment Panel III (2001) were used for assessment of metabolic syndrome. RESULTS: The prevalence of metabolic syndrome was high (about 30-50%) among the Bhutia, with no significant rural-urban difference. Among the Toto, though the prevalence of metabolic syndrome was low (about 4-9%), their lipid levels were alarmingly adverse (about 37-67% had low HDLcholesterol or high triglyceride levels). There was an additional adverse impact of adoption of urban life-styles (perhaps primarily mediated through dietary changes) on cardiovascular risk factors. INTERPRETATION AND CONCLUSION: Our study suggested that metabolic syndrome and its correlates could be a major health problem even in traditional societies, indicating that this syndrome was not necessarily a result of modernization. Further, our study indicates that genetic factors that adversely affect the levels of such variables have long antiquities in Indian ethnic groups.

Crystallization and preliminary X-ray studies of psophocarpin B1, a chymotrypsin inhibitor from winged bean seeds.

Psophocarpin B1 is a 20,000 Mr protein of winged bean (Psophocarpus tetragonolobus) seeds having chymotrypsin inhibitory activity. Single crystals of this protein suitable for X-ray crystallographic studies have been obtained by the vapour diffusion method using ammonium sulphate. The crystals are hexagonal, space group P6(4)22 or P6(2)22, cell dimensions a = b = 61 A, c = 210 A. They are stable to irradiation with X-rays and diffract to at least 2.6 A resolution.

Effects of L-5-hydroxytryptophan on monoamine and amino acids turnover in the Lesch-Nyhan syndrome.

In a patient with the Lesch-Nyhan syndrome we found decreased spinal fluid 5-hydroxyindole acetic acid (5-HIAA), the major metabolite of serotonin, and decreased homovanillic acid (HVA), the major metabolite of dopamine, indicating a decrease in monoamine metabolism. Administration of 5-hydroxytryptophan and carbidopa produced an increase in spinal fluid 5-HIAA, indicating that it might be possible to correct the serotonin deficiency in this syndrome, but there were no changes in the marked mental retardation and neurological deficits. Self-mutilation appeared to be suppressed by therapy but the effectiveness of the drugs decreased with time. There were also changes in the spinal fluid concentration of amino acids that might affect brain protein synthesis. These changes were corrected during administration of 5-hydroxytryptophan and carbidopa.

Arrhenius plots for activation energy of atomization in graphite-furnace atomic-absorption spectrometry.

Activation energy plots drawn by use of various Arrhenius-type equations for atomization reactions in graphite-furnace atomic-absorption spectrometry (GFAAS) do not give reliable kinetic information about the atomization mechanism of the analyte element beyond a few data-points located near the very beginning of the absorbance signal profile. These plots are non-linear if they are drawn with data points near the maximum of the absorbance signal profile. This paper presents two Arrhenius-type equations which give linear plots over a long range of data-points, and hence reliable values for the activation energy. Also, a simple method is proposed for calculating the activation energy from the data-points anywhere from the initial appearance of the absorbance signal to its maximum. Activation energy values given by these two equations and by the method of calculation are compared with each other and with those given by the commonly used methods. The calculated activation energy values obtained can be used to verify those obtained experimentally. The three proposed methods also provide reliable kinetic information on atom-formation reactions in GFAAS. A mechanism for the atomization of copper, based on the experimentally determined activation energy and reaction order is proposed.

Mechanism of cobalt atomization from different atomizer surfaces in graphite-furnace atomic-absorption spectrometry.

The mechanism of cobalt atomization from different atomizer surfaces in graphite-furnace atomic-absorption spectrometry has been investigated. The atomizer surfaces were pyrolytically coated graphite, uncoated electrographite, and glassy carbon. The activation energy of the rate-determining step in the atomization of cobalt (taken as the nitrate in aqueous solution) in a commercial graphite furnace has been determined from a plot of log k(s) vs. 1/T (for T values greater than the appearance temperature), where k(s) is a first-order rate constant for atom release, and T is the absolute temperature. The activation energy E(a), can be correlated either with the dissociation energy of CoO(g) or with the heat of sublimation of Co(s), formed by carbon reduction of CoO(s), the latter being the product of the thermal decomposition of Co(NO(3))(2). The mechanism for Co atomization seems to be the same for the pyrolytically coated graphite and the uncoated electrographite surfaces, but different for the glassy carbon surface. The suggested mechanisms are consistent with the chemical reactivity of the three atomizer surfaces, and the physical and thermodynamic properties of cobalt and its chemical compounds in the temperature range involved in the charring and atomization cycle of the graphite furnace.

Evaluation of a carbon-rod atomizer for routine determination of trace metals by atomic-absorption spectroscopy applications to analysis of lubricating oil and crude oil.

A carbon-rod atomizer (CRA) fitted with a 'mini-Massmann' carbon rod was evaluated for routine analysis of petroleum and petroleum products for trace metal content by atomic-absorption spectroscopy. Aspects investigated included sensitivity, detection limit, effect of solvent type, and interferences. The results of analysis of oil samples with this technique were compared with those obtained by other techniques. Metals studied were silver, copper, iron, nickel, and lead. Sensitivity and detection limit values obtained with the CRA were similar to those obtained with the carbon-filament atomizer. Strong 'solvent effects' were observed as well as interference by cations. On the basis of this study, design changes for the CRA are suggested, with the object of minimizing 'solvent effects' and interferences, increasing the atomization efficiency, and increasing the residence time of the atomic vapour in the optical path of the instrumental system.

Some aspects of "chemical" interferences in atomic-absorption spectroscopy.

Studies on the mutual chemical interferences in the atomic-absorption spectroscopy of Ca, Mg, Ba, Sr, Ti, Zr, Hf, Fe, as simple salts and metallocenes, show that the results can be interpreted in terms of formation of mixed oxides of two elements, non-volatility of the mixed oxide compound, and the crystal structure of the mixed oxide compound.

Studies on the stability of dithiocarbamic acids.

The influence of the substituent on the nitrogen atom with respect to the rate and pattern of decomposition of N,N-disubstituted dithiocarbamie acids has been studied. The rates of decomposition with respect to such variables as pH, temperature (activation parameters) and heavy water medium (solvent isotope effect), have been determined, and a mechanism to accommodate the observed results has been proposed.

Studies of atomization from a graphite platform in graphite-furnace atomic-absorption spectrometry.

A theoretical model has been proposed for the transient characteristics of an atomic-absorption pulse generated by atomization from a graphite platform in a pulse-heated graphite-furnace atomic-absorption spectrometer. The model has been used (with the aid of a computer program) to predict the effects of various factors on analyte atom populations as a function of time. The various factors studied were heating rate, initial temperature of the graphite tube wall, platform mass and thickness, and activation energy for the rate-determining step in the reaction sequence leading to atom formation. The results predicted by the model are in reasonable agreement with the experimental results obtained by using lead as the analyte element.

Schizonts, merozoites, and phagocytosis in falciparum malaria.

Two Nigerian siblings, ages 10 and 4 years, respectively, were infected with Plasmodium falciparum and were admitted to the hospital on the same day. The younger child died on the day of admission, but the older child survived. The peripheral blood smears of the younger patient showed the ring forms, schizonts, free merozoites, and phagocytosis of malarial parasites by both monocytes and polymorphonuclear leukocytes, whereas the smear from the older patient revealed only ring forms. The prognostic significance of this unusual observation and the host factors that affect the survival of the patients are discussed. This is the first documented case in which phagocytosis of malarial parasites by polymorphonuclear leukocytes is observed.

A digit-serial architecture for gray-scale morphological filtering.

We present a digit-serial architecture for gray-scale morphological operations that operate on radix-2 redundant numbers. We present new implementations for a redundant number adder and a maximum unit that are used in the morphological dilation unit. These new designs have areas comparable to 2's complement implementations but have significantly smaller latencies.

Effects of irrigation with raw and differentially diluted sewage and application of primary settled sewage-sludge on wheat plant growth, crop yield, enxymatic changes and trace element uptake.

An increase in the concentration of Cu, Zn, Cr and Mn, and a decrease in the activities of aspartate amino transferase, alanine amino transferase and peroxidase were observed in the different fractions of wheat plants, following raw and differentially diluted (66% and 50%) sewage irrigation and dry primary settled sewage-sludge amendments of soils. The grain enrichment efficiencies for Cu, Zn and Mn were significantly low under all experimental conditions. On the other hand, the grain enrichment efficiency for Cr was low under all sewage irrigation conditions only. Except in the earheads of wheat plants from sludge-amended soil, catalase activities were significantly low in roots, stems and earheads of wheat plants, under all other treatment conditions investigated. The decrease in the proteinase activity was statistically significant in roots and earheads of sewage-irrigated plants; the activity in the stem was low following irrigation with raw and 66% sewage only. Proteinase activity was also significantly low in all fractions of wheat plants harvested from soil amended with 20 tonnes of sludge per hectare. The observed results appear to be due to an overall decrease in the metabolic status of the plants following sewage irrigation and sludge amendment of soils. Grain yields, however, were not reduced despite this metabolic effect.

Differential C-heterochromatin distribution in two species of freshwater fish, Anabas testudineus (Bloch.) and Puntius sarana (Hamilton.).

Anabas testudineus (2n = 46) had the more conserved pattern of its C-heterochromatin distributed mainly in the centromeric region, whereas Puntius sarana (2n = 50) exhibited a rather unorthodox pattern, many chromosomes showing interstitial, some telomeric and a few chromosomes showing centromeric C-band localization. Further, lateral asymmetry in distribution of heterochromatin was also noted in two pairs of chromosomes in P. sarana. The possible implications of the differential distribution noted in these two species has been discussed.

Effects of jambolan seed treatment on blood sugar, lipids and urea in streptozotocin induced diabetes in rabbits.

In New Zealand rabbits a single intravenous injection of streptozotocin (STZ 65 mg/kg) elevated the levels of blood sugar to 340 mg percent, which was associated with glycolysis, ureamia, hypercholesterolemia, hypertriglyceridemia and loss of body weight. Oral administration of jambolan seed (1 g/kg) in casein diet significantly lowered the elevated postmeal (1 1/2 hr after) values of blood sugar, cholesterol, FFA and triglyceride down to levels comparable to phenformin. Jambolan seed treatment failed to check ureamia. Weight loss was checked by phenformin and jambolan seed but the gain was not equivalent to that recorded in nondiabetic control. Like phenformin, jambolan seed too failed to control glycogenolysis in STZ-induced diabetes.

Changes in the activity of some hepatic enzymes during organophosphorus insecticide-acephate (orthene) treatment in albino rats.

Acephate, an organophosphorus insecticide (60 mg/day/rat) disturbed the carbohydrate metabolism in albino rats (wt. between 100-150 gms). Changes in the enzyme activities in the liver were estimated in the rats after oral administration of Acephate. The specific activities of succinic dehydrogenase was decreased in experimental rats than control. A gradual decrease in blood and liver glutathione was also observed. Increase in total lactate dehydrogenase was also noted. It has been observed that in the liver homogenate of treated rats, the isoenzymes LDH4+5 were increased, LDH1+2 were decreased while LDH3 remain unchanged with respect to control value.

Effect of acephate (orthene) on tissue levels of thiamine, pyruvic acid, lactic acid, glycogen and blood sugar.

Effect of Acephate, an organophosphorus insecticide, on tissue levels of thiamine, pyruvic acid, lactic acid, glycogen and blood sugar, has been studied. The albino rats, injected subcutaneously with Acephate (25 mg/10 gm body wt./day) for 4 weeks and 8 weeks, showed appreciable depletion of thiamine in liver, heart, kidney, brain and blood. The depletion of thiamine was found to be more after 8 weeks of Acephate injection. There was concomitant increase in pyruvic acid and lactic acid in various tissues. There was enormous depletion of glycogen in liver and slight rise in blood sugar concentration. The animals injected thiamine (120 micrograms/100 gm body wt./day) along with Acephate, showed more or less normal levels of thiamine, pyruvic acid, lactic acid, liver glycogen and blood sugar. The increase in pyruvic acid and lactic acid in tissues has been attributed to depletion of thiamine which is required of pyruvic acid oxidation. The increase in blood sugar has been attributed to the excess breakdown of glycogen.