Effect of particle size distribution on magnetic behavior of nanoparticles with uniaxial anisotropy

The effect of particle size distribution on the field and temperature dependence of the hysteresis loop features like coercivity(H_C), remanence(M_R), and blocking temperature(T_B) is simulated for an ensemble of single domain ferromagnetic nanoparticles with uniaxial anisotropy. Our simulations are based on the two-state model for T T_B and the metropolis Monte-Carlo method for T T_B. It is found that the increase in the grain size significantly enhances H_C and T_B. The presence of interparticle exchange interaction in the system suppresses H_C but causes MRto significantly increase.Our results show that the parameters associated with the particle size distribution(D_(d,δ)) such as the mean particle size d and standard-deviation δ play key roles in the magnetic behavior of the system.     

6-Hydroxyhexyl 4-(E)-4-alkoxy/halostyryl)benzoates: synthesis,characterisation and study of mesomorphic and fluorescent properties

Hydroxyhexyl esters of alkoxy and halostilbene carboxylic acids were prepared and studied for thermal, liquid crystalline and fluorescent properties. The decomposition temperatures were determined thermogravimetrically and the compounds were found stable at least up to 200°C. Differential scanning calorimetry (DSC) indicated two mesophases in alkoxystilbene caboxylates. The smectic nature of the liquid crystal (LC) compounds was identified from the optical textures and confirmed through X-ray diffraction (XRD) measurements, where SmA, SmB and CrE mesophases were observed. The compounds 3a-g and 3h-k show single absorption maxima in UV-visible spectra at around 338 and 322 nm, respectively. All the alkoxy compounds emit blue light in solution and in solid state in the wavelength range of 422–425 nm.     

Microbial Transformations of (+)-Isomenthol by Fusarium lini and Rhizopus stolonifer

Microbial transformation of (+)-isomenthol (1) by various strains of fungi was investigated. Fusarium lini has successfully converted compound 1 into a new metabolite, 5α-hydroxyisomenthol (2), and a known metabolite, 1α-hydroxyisomenthol (3), whereas incubation with Rhizopus stolonifer only yielded metabolite 3. The transformed metabolites were structurally characterized on the basis of their spectral data.     

Novel Ferrocenyl Linked Pyrazoline Analogs as Potent Antiamoebic Agents

Some novel ferrocenyl linked pyrazoline analogs were synthesized, well characterized, and evaluated for in vitro antiamoebic activity against HM1 : IMSS strain of Entamoeba histolytica. Most of the compounds exhibited higher antiamoebic activity with the IC₅₀ value in the range of 0.12–1.20 μM, than the reference drug metronidazole, (IC₅₀ value of 1.78 μM). Compound 9 showed the most promising antiamoebic activity (IC₅₀ = 0.12 μM), concluding that these compounds hold immense potential to be employed as new antiamoebic agents. Also, being novel, they can be a solution to the increasing resistance that has posed a major problem globally.     

Isolation of three sesquiterpene lactones from the roots of Cichorium glandulosum Boiss. et Huet. by high-speed counter-current chromatography

Because of the skeletal complexity and similarity of the polarity, little research was reported on the isolation of sesquiterpene lactones by high-speed counter-current chromatography (HSCCC). Herein, three sesquiterpene lactones were successfully purified from the ethyl acetate extract of the roots of the traditional Uyghur medicinal plant Cichorium glandulosum Boiss. et Huet. by HSCCC. The separation was performed in two steps with two solvent systems: n-hexane-ethyl acetate-methanol-water (1.5:5:2.75:5, v/v/v/v) and ethyl acetate-methanol-water (20:1:20, v/v/v). From 166 mg of the ethyl acetate extract, 19 mg of lactucopicrin was isolated with the first solvent system and 10 mg of 11beta,13-dihydrolactucin and 16 mg of lactucin were obtained with the second solvent system. All purified compounds were over 94% purity as determined by HPLC analysis, and these chemical structures were confirmed by (1)H NMR and (13)C NMR.