Finite size effects on the structural and magnetic properties of sol–gel synthesized NiFe2O4 powders

Nanoparticles of nickel ferrite have been synthesized by the sol–gel method and the effect of grain size on its structural and magnetic properties have been studied in detail. X-ray diffraction (XRD) studies revealed that all the samples are single phasic possessing the inverse spinel structure. Grain size of the sol–gel synthesized powders has been determined from the XRD data and the strain graph. A grain size of 9 nm was observed for the as prepared powders of NiFe₂O₄ obtained through the sol–gel method. It was also observed that strain was induced during the firing process. Magnetization measurements have been carried out on all the samples prepared in the present series. It was found that the specific magnetization of the nanosized NiFe₂O₄ powders was lower than that of the corresponding coarse-grained counterparts and decreased with a decrease in grain size. The coercivity of the sol–gel synthesized NiFe₂O₄ nanoparticles attained a maximum value when the grain size was 15 nm and then decreased as the grain size was increased further.     

Ferromagnetic properties of glucose coated Cu2O nanoparticles

Magnetic properties of glucose coated cuprous oxide nanoparticles of different sizes have been studied. Unlike bulk Cu₂O, which shows diamagnetic behavior, the nanoparticles show superparamagnetic behavior. A superparamagnetic blocking temperature of 21 K is observed for 5 nm particles. A magnetic hysteresis loop with a coercivity of 406 Oe is observed for these particles at 5 K. The magnetization and the coercivity increase with decreasing particle size. The superparamagnetic behavior, along with the increase in magnetization and coercivity with decreasing particle size, is due to the enhanced surface contributions to the magnetism.     

Normal cirulant graphs with noncyclic regular subroups

We prove that any circulant graph of order n with connection set S such that n and the order of ?(S), the subgroup of ? that fixes S set‐wise, are relatively prime, is also a Cayley graph on some noncyclic group, and shows that the converse does not hold in general. In the special case of normal circulants whose order is not divisible by 4, we classify all such graphs that are also Cayley graphs of a noncyclic group, and show that the noncyclic group must be metacyclic, generated by two cyclic groups whose orders are relatively prime. We construct an infinite family of normal circulants whose order is divisible by 4 that are also normal Cayley graphs on dihedral and noncyclic abelian groups. © 2005 Wiley Periodicals, Inc. J Graph Theory     

Studies of the Interaction of Platinum Drugs with DNA Using Oligonucleotide Microarrays

Summary: A novel method for the study of the interaction of the platinum drug cis-diamminedichloroplatinum(II) (cis-DDP or cisplatin) with 50-mer oligonucleotides that were printed in high throughput microarray format is introduced. Our aim has been to identify sequence level differences in the interaction of various drug candidates that may serve to enable rational targeting of drugs to specific genes. A microarray of 26 control genes commonly used in oligonucleotide, Affymetrix and c-DNA microarray platforms were microcontact spotted as amine-terminated 50-mer oligonucleotides onto glycidoxypropyltimethoxy silane (GPMS)-modified glass slides. The generalized study format involved hybridization of probes with 10 fluorescently labeled complements as target followed by confocal imaging to reveal original spot intensities. Microarrays were then incubated at 37 °C with hydrolysed cisplatin while in hybridization cassettes, washed in buffer and then scanned again to reveal secondary intensities. We have investigated the influence of cisplatin to stabilize the relative fluorescence intensity via intrastrand crosslinking by studying the impact of varying drug:probe-DNA mole ratio (0:1 (blank), 1:1, 25:1 and 50:1) and annealing temperatures (36, 46, or 56 °C) on retained intensity. ANOVA revealed that 4 of the 10 genes demonstrated (p < 0.0001) the expected result of increased signal retention with decreased temperature and increased drug concentration.     

Fermentations of pectin-rich biomass with recombinant bacteria to produce fuel ethanol

Pectin-rich residues from sugar beet processing contain significant carbohydrates and insignificant amounts of lignin. Beet pulp was evaluated for conversion toethanol using recombinant bacteria as biocatalysts. Hydrolysis of pectin-rich residues followed by ethanolic fermentations by yeasts has not been productive because galacturonic acid and arabinose are not ferm entable toethanol by these organisms. The three recombinant bacteria evaluated in this study, Escherichia coli strain KO11, Klebsiella oxytoca strain P2, and Erwinia chrysanthemi EC 16 pLOI 555, ferment carbohydrates in beet pulp with varying efficiencies. E. coli KO11 is able to convert pure galactu ronic acid to ethanol with minimal acetate production. Using an enzyme loading of 10.5 filter paper un its of cellulase, 120.4 polygalactu ronase units of pectinase, and 6.4 g of cellobiase (per gram of dry wt sugar beet pulp), with substrate addition after 24 h of fermentation, 40 g of ethanol/L was produced. Other recombinants exhibited lower ethanol yields with increases in acetate and succinate production.     

A rapid approach for the copper,amine, and ligand-free Sonogashira coupling of 4-methyl-7-nonafluorobutylsulfonyloxy coumarins under microwave irradiation

A rapid, efficient, and reliable access for the synthesis of an assortment of 4-methyl-7-alkyl/aryl/heteroaryl alkynyl coumarins has been developed by the copper, amine, and ligand-free Sonogashira cross-coupling reaction of 4-methyl-7-nonafluorobutylsulfonyloxy coumarin with various terminal alkynes under microwave irradiation. In the presence of a suitable catalyst, base, and solvent, the coupling reaction proceeded smoothly to give the diaryl alkynes in satisfactory to exceptional yields. Nonaflates coupled more efficiently than the corresponding triflates which yielded the detriflated product as well as the hydrolyzed product as competing side products along with the required product. The utilization of TBAF·3H₂O as a mild base as well as a solvating agent was the key for success of the reaction.     

Vocal characteristics of pygmy blue whales and their change over time

Vocal characteristics of pygmy blue whales of the eastern Indian Ocean population were analyzed using data from a hydroacoustic station deployed off Cape Leeuwin in Western Australia as part of the Comprehensive Nuclear-Test-Ban Treaty monitoring network, from two acoustic observatories of the Australian Integrated Marine Observing System, and from individual sea noise loggers deployed in the Perth Canyon. These data have been collected from 2002 to 2010, inclusively. It is shown that the themes of pygmy blue whale songs consist of ether three or two repeating tonal sounds with harmonics. The most intense sound of the tonal theme was estimated to correspond to a source level of 179 ± 2 dB re 1 μPa at 1 m measured for 120 calls from seven different animals. Short-duration calls of impulsive downswept sound from pygmy blue whales were weaker with the source level estimated to vary between 168 to 176 dB. A gradual decrease in the call frequency with a mean rate estimated to be 0.35 ± 0.3 Hz/year was observed over nine years in the frequency of the third harmonic of tonal sound 2 in the whale song theme, which corresponds to a negative trend of about 0.12 Hz/year in the call fundamental frequency.     

First report of anti-inflammatory chromenyl derivatives from the spineless cuttlefish Sepiella inermis

Abstract

The spineless cuttlefish Sepiella inermis encompasses a major share in the marine fisheries sector, and represents as a culinary delicacy in many cultures. Bioactivity-guided fractionation of methanol:ethyl acetate (MeOH:EtOAc, 1:1) extract of the edible parts of the species ensued in identification of two hexahydro chromenyl analogues namely, methyl 7-ethyl-hexahydro-8a-methyl-2H-chromene-4-carboxylate (1) and methyl 1-acetoxy-hexahydro-3-methyl-3-propyl-1H-isochromene-4-carboxylate (2). The isolated metabolites were checked for their radical scavenging and anti-inflammatory potentials by selective in vitro models. The isochromenyl derivative exhibited potential 2,2-diphenyl-1-picryl-hydrazil and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (IC₅₀?<?0.45?mg mL^?1) radical-scavenging capacities along with pro-inflammatory cyclooxygenase-2 (COX-2) (IC₅₀ 0.75?mg mL^?1) and 5-lipoxygenase (5-LOX) (IC₅₀ 0.77?mg mL^?1) inhibitory activities. The titled compounds displayed the selectivity indices (IC₅₀ anti-COX-1/IC₅₀ anti-COX-2) greater than 1.25, in comparison with synthetic anti-inflammatory drug ibuprofen (0.44), which attributed to their greater selectivity towards inducible pro-inflammatory enzyme COX-2.