The growth and improved magnetoelectric response of strain-modified Aurivillius SrBi4.25La0.75Ti4FeO18 thin films.

In this study, we grew 5-layered SrBi4.25La0.75Ti4FeO18 (SBLFT) polycrystalline thin films (80-330 nm thick) via pulsed-laser deposition to study their ferroelectric and magnetoelectric response. Structural/microstructural analysis confirmed the formation of orthorhombic SBLFT with good crystallinity and randomly oriented Aurivillius phases. Detailed scanning transmission electron microscopy analysis of 120 nm film revealed a predominantly five-layered structure with the coexistence of four-layer stacking. Such stacking defects are found to be pertinent to the high structural flexibility of Bi-rich Aurivillius phases, alleviated by lattice strain. Raman spectral features at ambient temperatures depict the signature of the orthorhombic-tetragonal phase transition. SBLFT films have a strong ferroelectric nature (remanent polarization 2Pr of 35 µC cm-2) with a fatigue endurance up to 1010 cycles and strongly improved, switchable magnetization as opposed to its antiferromagnetic bulk counterpart. The scaling behavior of dynamic hysteresis reveals that ferroelectric domain reversal has good stability and low energy consumption. We observed the presence of SBLFT nanoregions (1-5 nm), distributed across the film, with Bi and Fe-rich compositions and oxygen vacancies that contribute to the weak ferromagnetic behavior mediated by the Dzyaloshinskii-Moriya interactions. Subtle changes in the structural strain and lattice distortions of thin films with varied thicknesses led to distinct ferroic properties. Stronger ferroelectric polarization of 80 nm and 120 nm films compared to that of thicker ones can be due to structural strain and the possible rearrangement of BO6 octahedra. The observation of the improved magnetoelectric coefficient of 50 mV cm-1 Oe-1 for 120 nm film, as compared to that of several Aurivillius oxides, indicates that the structural strain modification in SBLFT is beneficial for the fatigue-free magnetic field switching of ferroelectric polarization. The structural strain of the unit cell as well as the presence of Bi- and ferromagnetic Fe-rich nanoregions was found to be responsible for the improved multiferroic behaviour of the SBLFT films.

Cadmium toxicity-induced proline accumulation is coupled to iron depletion.

Investigations were conducted to elucidate the key factor behind Cd2+-toxicity-induced proline accumulation in Indian mustard (Brassica juncea) by raising seedlings, independently in distilled water (DW) and mineral growth medium (MGM) in the presence of 0-500 µM CdCl2. Invariably, Cd2+-induced toxicity, measured in terms of growth, was significantly more prominent in seedlings raised in DW than those raised in MGM. Cd2+ brought about a significant reduction in growth and photosystem II activity with a concomitant increase in proline levels, in a concentration-dependent manner. Interestingly, the level of iron in shoots of seedlings decreased proportionately with increase in Cd2+ toxicity. Cd2+-promoted proline accumulation was significantly higher in seedlings raised in DW than those raised in MGM. Depletion of essential cations (viz. Ca2+, Mg2+, K+, and Fe2+) from MGM one at a time revealed that depletion of Fe2+ leads to maximal proline accumulation under Cd2+ toxicity. Interestingly, proline level in seedlings raised under Cd2+ toxicity in DW supplemented with Fe2+ was similar to that recorded in seedlings raised in MGM. Our results convincingly demonstrated that Cd2+-induced iron deficiency promotes proline accumulation.

Formulation, characterization and pulmonary deposition of nebulized celecoxib encapsulated nanostructured lipid carriers.

The aim of the current study was to encapsulate celecoxib (Cxb) in the nanostructured lipid carrier (Cxb-NLC) nanoparticles and evaluate the lung disposition of nanoparticles following nebulization in Balb/c mice. Cxb-NLC nanoparticles were prepared with Cxb, Compritol, Miglyol and sodium taurocholate using high-pressure homogenization. Cxb-NLC nanoparticles were characterized for physical and aerosol properties. In-vitro cytotoxicity studies were performed with A549 cells. The lung deposition and pharmacokinetic parameters of Cxb-NLC and Cxb solution (Cxb-Soln) formulations were determined using the Inexpose system and Pari LC star jet nebulizer. The particle size and entrapment efficiency of the Cxb-NLC formulation were 217+/-20nm and >90%, respectively. The Cxb-NLC released the drug in controlled fashion, and in-vitro aerosolization of Cxb-NLC formulation showed an FPF of 75.6+/-4.6%, MMAD of 1.6+/-0.13microm and a GSD of 1.2+/-0.21. Cxb-NLC showed dose and time dependent cytotoxicity against A549 cells. Nebulization of Cxb-NLC demonstrated 4 fold higher AUC(t)/D in lung tissues compared to the Cxb-Soln. The systemic clearance of Cxb-NLC was slower (0.93l/h) compared to the Cxb-Soln (20.03l/h). Cxb encapsulated NLC were found to be stable and aerodynamic properties were within the respirable limits. Aerosolization of Cxb-NLC improved the Cxb pulmonary bioavailability compared to solution formulation which will potentially lead to better patient compliance with minimal dosing intervals.

Gaseous oxygen uptake in porous media at different moisture contents and airflow velocities.

The presence and distribution of water in the pore space is a critical factor for flow and transport of gases through unsaturated porous media. The water content also affects the biological activity necessary for treatment of polluted gas streams in biofilters. In this research, microbial activity and quantity of inactive volume in a porous medium as a function of moisture content and gas flow rate were investigated. Yard waste compost was used as a test medium, and oxygen uptake rate measurements were used to quantify microbial activity and effective active compost volume using batch and column flow-through systems. Compost water contents were varied from air-dry to field capacity and gas flows ranged from 0.2 to 2 L x min(-1). The results showed that overall microbial activity and the relative fraction of active compost medium volume increased with airflow velocity for all levels of water content up to a certain flow rate above which the oxygen uptake rate assumed a constant value independent of gas flow. The actual value of the maximum oxygen uptake rate was controlled by the water content. The oxygen uptake rate also increased with increasing water content and reached a maximum between 42 and 48% volumetric water content, above which it decreased, again likely because of formation of inactive zones in the compost medium. Overall, maximum possible oxygen uptake rate as a function of gas flow rate across all water contents and gas flows could be approximated by a linear expression. The relative fraction of active volume also increased with gas flow rate and reached approximately 80% for the highest gas flows used.

Pharmacokinetics of gadoversetamide injection, a gadolinium-based contrast agent, in pediatric patients.

OBJECTIVE: The pharmacokinetics of gadoversetamide were examined in pediatric patients scheduled to undergo contrast-enhanced MRI of the central nervous system. MATERIALS AND METHODS: One hundred patients received an intravenous injection of gadoversetamide at a dose of 0.1 mmol/kg for a contrast-enhanced MRI procedure. A subpopulation of 30 patients were enrolled to evaluate the pharmacokinetics of gadoversetamide in patients 2-11 and 12-18 years of age. Serial blood and urine samples were collected before and after the administration of gadoversetamide. RESULTS: The terminal half-life, initial concentration and area under the curve assessments for gadoversetamide showed no significant (P>.05) differences between the age groups or the sexes. Although no sex-related differences occurred in the volume of distribution or clearance, significant (P<.05) age-related differences were found, but once corrected for body mass or surface area the differences were no longer significant. CONCLUSIONS: The pharmacokinetic behavior of gadoversetamide was not significantly altered by differences in age or sex in pediatric patients from 2 to 18 years of age. Although significant differences in volumes of distribution, and clearance occurred between the age groups, these differences appeared to depend on body size rather than on age in pediatric patients between 2 and 18 years of age.

Cholesterol-lowering effect of organosulphur compounds from garlic: a possible mechanism of action.

OBJECTIVES: Hyperlipidemia constitutes a major etiopathological factor for atherosclerosis. The medicinal value of garlic is best known for its lipid lowering effects and antiatherogenic effects. The mechanism by which lipid soluble organosulphur compounds from garlic reduce plasma lipids has not been fully investigated. The author had previously shown that the hepatic activity of beta-hydroxy-beta-methylglutaryl-CoA (HMG-CoA) reductase, the rate limiting enzyme in cholesterol biosynthesis and the incorporation of radiolabeled (1, 2 14C), acetate into hepatic free and esterified cholesterol was significantly decreased in rat treated with garlic derived organosulphur compounds. We hypothesised that the antiatherogenic effect of the organosulphur compounds may be attributed to the formation of protein internal disulphide and thus inactivation of thiol (-SH) group enzymes such as HMG-CoA reductase and the multienzyme complex of fatty acid synthesis. The objective of the present study is to elucidate the inhibitory mechanism by in vitro studies. METHOD: Lipid soluble organosulphur compounds from garlic were treated in vitro with Luke's cysteine reagent (representing the thiol (-SH) group of enzymes) and the interaction products were separated by paper chromatography. RESULT: The result indicated that the organosulphur compounds were capable of interacting with the thiol (-SH) group of cysteine and thus forming cysteine derivatives. CONCLUSION: The antiatherogenic effects of these organosulphur compounds can be attributed to such reactions that inhibit HMG-CoA reductase and other lipogenic enzymes. The anticarcinogenic effects of these compounds may also be due to inhibitory reactions on enzymes that activate carcinogens.

Quantitative echocardiographic image texture: normal contraction-related variability.

Myocardial tissue characterization using ultrasound is a growing area of investigation which attempts to evaluate the structure of the myocardium by analysis of ultrasound signals. Our laboratory has been exploring the use of texture analysis for the determination of myocardial tissue properties from two-dimensional echocardiographic images. In the present study, we tested the hypothesis that echocardiographic image texture varies with cardiac contraction in normal human subjects. In 17 subjects, we obtained long-and short-axis images at end diastole and end systole. Echo image texture was assessed using three classes of quantitative texture measures: run length, gray level difference, and busyness statistics. These statistics measure various attributes of image texture. We found significant contraction-related changes in image texture for the left ventricular posterior wall. This observation is important in that future applications of texture analysis to echocardiographic image data will require that texture be measured at a consistent point in the cardiac cycle. Moreover, it is possible that alteration in the normal variation of texture with cardiac contraction may be a sensitive indicator of abnormal myocardium.

Variation of left ventricular myocardial gray level on two-dimensional echocardiograms as a result of cardiac contraction.

Integrated ultrasonic backscatter from normal myocardium has been shown to vary with the phase of cardiac contraction (decreasing from end-diastole to end-systole) in previous studies of open-chest dogs. If confirmed, this finding would have important implications for clinical application of ultrasonic tissue characterization. Our hypothesis was that a cardiac cycle-dependent variation in regional average gray level would be detected on analysis of digitized two-dimensional echocardiograms. We analyzed echocardiographic images from 16 subjects in whom normal, technically good studies were obtained with a commercial phased-array scanner and a 2.25 MHz transducer. Images from six subjects were digitized from stop-frame photographs and those from 10 subjects were obtained directly in digital format from the scanner. Average gray level was measured in a portion of the left ventricular posterior wall in parasternal long-axis images obtained at end-diastole and end-systole by both photographic and digital-image acquisition. In seven of the subjects from whom digital images were acquired, left ventricular posterior wall gray level and ventricular septal gray level were also evaluated on parasternal short-axis images. In images digitized by the photographic technique, mean posterior wall gray level decreased significantly from end-diastole (175 +/- 5.8 SEM) to end-systole (167 +/- 5.1, p less than .05). Similarly, in images digitized directly, mean posterior wall gray level in the long-axis view decreased from end-diastole (71 +/- 3.4) to end-systole (59 +/- 2.5, p less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)