Coevaporation phosphorus doping in Si grown by molecular beam epitaxy

Phosphorus-doped Si epilayers with bulk-like mobilities were grown by molecular beam epitaxy (Si-MBE) by coevaporation of phosphorus from a tin phosphide source. The behaviour of P doping as a function of growth parameters and of potential enhanced doping indicates a non-unity, almost growth-temperature independent incorporation efficiency with negligible surface segregation -a unique combination among coevaporated dopants in Si-MBE.     

Simultaneous determination of itraconazole and hydroxyitraconazole in human plasma by high-performance liquid chromatography

The development and validation of a high-performance liquid chromatography (HPLC) method for the simultaneous determination of itraconazole and its metabolite, hydroxyitraconazole, in human plasma is described. The method involved liquid-phase extraction of itraconazole and hydroxyitraconazole using a hexane-dichloromethane (70:30) mixture, after addition of loratidine as an internal standard (IS). Separation was achieved with a reversed-phase C18 column (250 mm x 4.6 mm) employing fluorescence detection (excitation: 264 nm, emission: 380 nm). The mobile phase consisted of [0.01% triethylamine solution adjusted to pH 2.8 with orthophosphoric acid-acetonitrile (46:54)]-isopropanol (90:10, v/v) at a flow rate of 1.0 ml/min. For both the drug and metabolite, the standard curve was linear from 5.0 to 500 ng/ml with goodness of fit (r2) greater than 0.98 observed with four precision and accuracy batches during validation. An observed recovery was more than 70% for drug, metabolite and internal standard. The applicability of this method to pharmacokinetic studies was established after successful application during 35 subjects bioavailibity study. The method was found to be precise, accurate and specific during the study.     

Study of the mesomorphism of benzoates and cinnamates

Two ester homologous series of carboxy (-COO-) and ethylene-carboxy (-CH=CH-COO-) mesogens, viz. α-4-[4’-n-alkoxybenzoyloxy] phenyl β-4’’-methoxy benzoyl ethylenes (1) and α-4-[4’-n-alkoxy cinnamoyloxy phenyl β-4’’-methoxy benzoyl ethylenes (2)] are discussed. Series (1) and (2) differ at their central linking group. Mesophase are observed at four and five number members in both homologue series. Enantiotropic nematogenic property is observed in both series (1) and (2), while some smectic property is exhibited in series (2). Thermal stability of nematic-isotropic in series (1) is relatively low as compared to (2), smectogenic property is totally absent in series (2). In phase diagram, solid-nematic, solid-isotropic, and nematic-isotropic curve follow zigzag path rising and falling. Transition temperatures are observed through hot stage polarizing microscope. Analytical data supports the structure of molecules. Threaded, Schlieren-type textures of homologues are observed through microscope.     

Preparation,characterisation, and crystal structure analysis of (2<Emphasis Type="Italic">E</Emphasis>,2′<Emphasis Type="Italic">E</Emphasis>)-3,3′-(1,4-phenylene)bis(1-(2-aminophenyl)prop-2-en-1-one

A novel bis-chalcone, (2E,2′E)-3,3′-(1,4-phenylene)bis(1-(2-aminophenyl)prop-2-en-1-one) is synthesized through a base catalyzed Claisen-Schmidt condensation reaction of terephthalaldehyde with 2-aminoacetophenone. Its structure (sp. gr. P\(\bar 1\), Z = 2) is determined from single crystal X-ray diffraction data. There are two independent centrosymmetric molecules with no significant differences in bond lengths and angles between them. The NMR, IR, HRMS, and UV spectral data of the prepared bis-chalcone are presented.     

Regioselective 5‐endo‐dig Electrophilic Iodocyclization of Enediynes: A Convenient Route to Iodo‐substituted Indenes and Cyclopenta‐Fused Arenes

An efficient iodine‐mediated regioselective tandem approach for the synthesis of symmetric and asymmetric iodo‐substituted indenes and stereoselective cyclopenta [b]pyridine/thiophenes from easily accessible enediynes that proceeds by in situ formation of an iodonium intermediate followed by a regioselective 5‐endo‐dig cyclization has been described. The intramolecular electrophilic iodocyclization was selectively triggered by a distribution of electronic density along the alkyne bond. Subsequently, the iodo‐substituted indenes were diversified by employing palladium‐catalyzed cross‐coupling reactions and the coupled products were further confirmed by X‐ray crystallographic studies.     

A system of non-local parabolic PDE and application to option pricing

This article includes a proof of well posedness of an initial-boundary value problem involving a system of non-local parabolic partial differential equation (PDE), which naturally arises in the study of derivative pricing in a generalized market model, which is known as a semi-Markov modulated geometric Brownian motion (GBM) model We study the well posedness of the problem via a Volterra integral equation of second kind. A probabilistic approach, in particular the method of conditioning on stopping times is used for showing the uniqueness.