Mössbauer investigation of maghemite-based glycolic acid nanocomposite

Transmission electron microscopy, X-ray diffraction and Mössbauer spectroscopy were used in the characterization of a nanocomposite containing magnetic nanoparticles dispersed in a glycolic acid-based template. Maghemite nanoparticles were identified as the iron oxide phase dispersed in the polymeric template. From the low-temperature Mössbauer data the amount of the iron-based, non-magnetic material at the nanoparticle surface was estimated as roughly one monolayer in thickness.     

Study of molecular surface coating on the stability of maghemite nanoparticles

In this study γ-Fe₂O₃ nanoparticle, surface-coated with increasing amount of oleic acid, have been prepared while the stability against particle degradation under laser excitation intensity was investigated. Maghemite nanoparticle was obtained via oxidation of magnetite nanoparticle, the latter synthesized by co-precipitation of Fe (II) and Fe (III) ions in alkaline medium. By varying the experimental conditions of surface-coating maghemite nanoparticles with oleic acid, samples with different grafting coefficient were obtained and investigated using X-ray diffraction and different spectroscopic techniques, namely Raman, Mössbauer, and infrared. The amount of oleic acid adsorbed on the maghemite surface was estimated via the carbon content obtained from elemental analysis.     

Polycyclic aromatic hydrocarbons in C8 isomer aromatic feed: analysis by GC, GC/MS, and GC/FTIR techniques

Polycyclic aromatic hydrocarbons (PAHs), apart from their carcinogenic and mutagenic nature, create many problems in the petrochemical industry due to their tendency toward carbonization. Compounds in C8 aromatic isomer feed are analyzed by means of sample concentration, followed by separation of individual compounds by gas chromatography on a stainless steel OV-101 phase capillary column and identification by gas chromatography/mass spectrometry and gas chromatography/Fourier transform infrared spectroscopy. Various compounds belonging to different classes (mainly monocyclic, dicyclic, and tricyclic aromatics), oxygenated aromatics, and aliphatic saturates are quantified in the concentrated hydrocarbon residue of C8 isomer feed. Both unsubstituted and alkyl substituted ring type compounds are present. Concentrations obtained for PAH compounds in the C8 isomer feed range from 0.2 to 0.42 micrograms/mL.     

Completeness properties of the pseudocompact-open topology on <Emphasis Type="Italic">C</Emphasis>(<Emphasis Type="Italic">X</Emphasis>)

This is a study of the completeness properties of the space C _ps (X) of continuous real-valued functions on a Tychonoff space X, where the function space has the pseudocompact-open topology. The properties range from complete metrizability to the Baire space property. Dedicated to Professor Robert A. McCoy     

Lifetime measurements in Pt and the shape coexistence picture

Lifetimes for levels in the yrast band of ¹⁸⁴Pt have been measured up to spin 16⁺ using the recoil distance technique. The B(E2) values exhibit a marked increase in going from spin 2 to 10, consistent with a proposal that two bands of different deformations are mixing at low spin. This provides further support for shape coexistence occuring at low excitation energies in this region.     

Stable and tunable phosphorescent neutral cyclometalated Au(III) diaryl complexes

A series of novel luminescent cyclometalated Au(III) neutral complexes of the type cis-[(N(∧)C)AuL] [N(∧)C = 2-phenylpyridine (ppy), L = 1,1'-biphenyl (1)] and cis-[(N(∧)C)AuL(2)] [N(∧)C = 2-phenylpyridine (ppy), L = C(6)H(5) (2), C(6)F(5) (3), C(6)H(4)-CF(3)-p (4), 2-C(4)H(3)S (5)]; [N(∧)C = 2-(2-thienyl)pyridine (thpy), L = C(6)H(5) (6), C(6)F(5) (7)]; [N(∧)C = 2-(5-methyl-2-thienyl)pyridine (5 m-thpy), L = C(6)F(5) (8)] were successfully synthesized. The X-ray crystal structures of all compounds except 3 have been determined. These complexes were found to show long-lived emission in solution at room temperature. The emission origins of the complexes have been tentatively assigned to be derived from triplet states predominantly bearing intraligand (IL) character with some perturbation from the metal center. Density functional theory (DFT) calculations were performed to evaluate the stability associated with the complexes and TD-DFT calculations to ascertain the nature of the excited state. Variation of the cyclometalated ligands in the complexes readily leads to the tuning of the nature of the lower energy emissive states.     

Anti-ulcer activity of Smithia conferta in various animal

Smithia conferta Sm. (Leguminasae), is a commonly used plant in Indian traditional medicine. In the current study anti-ulcer activity of its petroleum ether, alcohol and aqueous extracts of leaves were investigated using different animal models. All extracts were also subjected to phytochemical analysis and their toxic potential. Petroleum ether extract was found to contain steroids; alcohol extract revealed the presence of isoflavonoids, alkaloids and carbohydrates; while aqueous extract was found to contain amino acids, carbohydrates and flavonoids. S. conferta aqueous and alcoholic extracts were found to be non-toxic up to 5000 mg/kg dose level while petroleum ether extract was safe only up to a dose of 2000 mg/kg after single dose administration of the extracts.During confirmation of the claimed anti-ulcer activity, treatment with aqueous and alcoholic extracts showed significant reduction in ulcer index, free acidity as well as total acidity in pylorus ligated rats. However, petroleum ether extract showed relatively less profound reduction in all these indices. The anti-ulcer activity observed in aqueous extract treatment group was nearly equivalent to the standard group.     

Preparation and characterization of hydroxypropyl-β-cyclodextrin inclusion complex of eugenol: differential pulse voltammetry and (1)H-NMR

The objective of present investigation was to improve the solubility of Eugenol by preparing the inclusion complex of Eugenol with hydroxypropyl-β-cyclodextrin (Hp-β-CD) and characterize the prepared complex by using NMR and differential pulse voltammetry (DPV). Phase solubility curve was plotted using Hp-β-CD in ranging from 0-40 mM of Hp-β-CD and found to be linear. Therefore, inclusion complex was prepared in equimolar ratio of Eugenol and Hp-β-CD by lyophilization method. Fourier transform infrared spectroscopy (FT-IR), (1)H-NMR and DPV were performed for Eugenol, Hp-β-CD and prepared inclusion complex of Eugenol. 2D (two dimensional) NMR was also performed for prepared inclusion complex. The proton of phenol moiety of Eugenol experienced a pronounced chemical shift variation in (1)H-NMR. The positive sign of the variation for proton in (1)H-NMR indicated that the proton was located near to an oxygen atom in the Hp-β-CD cavity and its magnitude showed a strong interaction between -OH proton of Eugenol and Hp-β-CD. 2D NMR confirms the interaction between phenolic group and hydrogen atoms of Hp-β-CD. A well defined anodic peak current corresponding to oxidation of Eugenol in non-encapsulated and Hp-β-CD-Eugenol inclusion complex in phosphate buffer (pH 6.8) was obtained at about 0.35 V and 0.40 V, respectively. The positive shift in oxidation potential indicated the formation of complex via hydrophobic interactions. The oxidant power of Eugenol was retained in complex form as indicated by DPV results. Thus, its oxidation dependent pharmacological property such as antimicrobial activity is not affected after complexation with Hp-β-CD. Thus, (1)H-NMR, 2D-NMR and DPV techniques can be used as valuable tools to determine the mechanism of complexation and state of electrochemical active drug in inclusion complex.     

Role of disorder and anharmonicity in the thermal conductivity of silicon-germanium alloys: a first-principles study

The thermal conductivity of disordered silicon-germanium alloys is computed from density-functional perturbation theory and with relaxation times that include both harmonic and anharmonic scattering terms. We show that this approach yields an excellent agreement at all compositions with experimental results and provides clear design rules for the engineering of nanostructured thermoelectrics. For Si(x)Ge(1-x), more than 50% of the heat is carried at room temperature by phonons of mean free path greater than 1 μm, and an addition of as little as 12% Ge is sufficient to reduce the thermal conductivity to the minimum value achievable through alloying. Intriguingly, mass disorder is found to increase the anharmonic scattering of phonons through a modification of their vibration eigenmodes, resulting in an increase of 15% in thermal resistivity.