Investigation of electrical transport in hydrogenated multiwalled carbon nanotubes

Highly disordered multiwalled carbon nanotubes of large outer diameter (∼60 nm) fabricated by means of chemical vapor deposition process inside porous alumina templates exhibit ferromagnetism when annealed in a H₂/Ar atmosphere. In the presence of an applied magnetic field, there is a transition from positive to negative magnetoresistance. The transition may be explained in terms of the Bright model for ordered and disordered carbon structures. Additionally, temperature dependent electrical transport experiments exhibit a zero-bias anomaly at low temperature.     

Spectroscopy and thermochemistry of a jet-cooled open-shell polyene: 1,4-pentadienyl radical

The 1,4-pentadienyl (vinylallyl) radical has been observed for the first time by optical spectroscopy. An excitation spectrum is recorded on m/z 67 by resonant two-color two-photon ionization spectroscopy. Several bands are observed with the origin transition identified at 19 449 cm(-1). The spectrum is assigned by a comparison with ab initio frequencies calculated at the CASPT2/cc-pVTZ level of theory, with an accompanying Franck-Condon calculation of the excitation spectrum, including Dushinsky mixing. The b(1) and a(2) outer C-C bond torsional modes are calculated to halve in frequency upon electronic excitation, bringing about their appearance in the excitation spectrum. This can be readily understood by considering the torsional sensitivity of the frontier molecular orbital energies. High-level quantum chemical calculations of the radical stabilization energy, resulting in a value of nearly 120 kJ mol(-1), provide quantitative confirmation that this radical is highly stabilized.     

Exploitation of detergent thermodynamics in the direct solubilization of myelin membrane proteins for two-dimensional gel electrophoresis for proteomic analysis

Performing 2-DE of lipid-rich multilamellar membranes like myelin is a cumbersome task. However, for understanding its molecular organization and changes during diseases, identification of proteins of myelin is essential. Although the 2-D-proteomic approach of myelin has been employed to understand the myelin proteome, representation of myelin proteins in its entirety is still a challenge. 2-DE profiling of myelin proteins is very important for the detection of immuno-reactivity to myelin proteins from various biological fluids following Western blotting in diseases like multiple sclerosis. Here we developed a novel approach by exploiting the thermodynamic principles behind detergent-mediated solubilization of myelin membranes without any conventional processing of myelin involving precipitation of myelin proteins. We show that the addition of myelin to ASB-14-4 resulted in significant increase in protein representation of myelin in 2-DE compared with the addition of ASB-14-4 to myelin. Moreover, the number and resolution of spots are significantly higher in myelin to ASB-14-4 strategy than other strategies of myelin sample processing such as ASB-14-4 to myelin or ethanol or acetone or methanol-ammonium acetate precipitation of myelin proteins. In addition, the step involves no precipitation that selective removal of any proteins as a result of precipitation is nil and a qualitative representation of myelin proteins in a 2-D gel is achieved.     

Evaluation and solubility improvement of Carvedilol: PSC[n]arene inclusion complexes with acute oral toxicity studies

The aqua phobic molecules that are practically insoluble in aqueous media demonstrate a staggeringly slow intrinsic dissolution rate. In this work, we exemplify the utility of calixarenes as a tool to form inclusion complexes with Carvedilol (CDL). It is poorly water soluble drug. CDL is a Biopharmaceutical Classification System (BCS) Class II drug and it is a nonselective β-adrenegenic blocking agent with α1-blocking activity. It is mainly used in the management of hypertension. The maximum complexation of the drug was accomplished after 48?h of stirring with para sulphonato calix[4]arene (PSC[4]arene) and para sulphonato calix[6]arene (PSC[6]arene) in water and evaporation of water to acquire solid complexes. The study includes characterisation of both the complexes—physical mixtures of drug and PSC[4]arene and PSC[6]arenes by different methods like Fourier-transform infra red spectroscopy, differential scanning calorimetry and powder X-ray diffraction, proton nuclear magnetic resonance. This studies shows that there is electrostatic interaction between drug and PSC[n]arenes. The complexation was determined by phase solubility study. The prepared complexes exhibited improved in vitro dissolution profile and decreased in vivo acute oral toxicity compared to the pure drug.     

1,2-Benzoquinones in Diels-Alder reactions, dipolar cycloadditions, nucleophilic additions, multicomponent reactions and more

A brief account of the recent developments in the chemistry of 1,2-benzoquinones is presented in this tutorial review. The title compounds exhibit commendable versatility in both Diels-Alder and dipolar cycloaddition reactions. They have also been employed as electrophilic reaction partners in nucleophile-triggered catalytic processes and related multicomponent reactions. These, along with other reactions described here, lead to the synthesis of densely functionalised carbocyclic and heterocyclic frameworks that are otherwise difficult to access.     

Essential oil composition of two unique ginger (Zingiber officinale Roscoe) cultivars from Sikkim

Volatile oils from two most popular cultivars from Sikkim namely, Bhaisa and Majulay, were isolated, characterised by analytical GC and GC-MS. Sixty constituents accounting for 94.9% and 92.6% of the Bhaisa and Majulay oils were identified. The major compounds of Bhaisa oil were geranyl acetate (18.8%), zingiberene (16.3%) and geranial (8.2%) and those of Majulay oil were zingiberene (19.8%) and geranial (16.5%). Compared to other ginger cultivar oils, the Bhaisa oil had higher content of oxygenated compounds (43.1%). This is the first report on the essential oils from Sikkim ginger cultivars.     

Synthesis and Mesomorphic Characterisation of Chiral Homologues

Abstract

Chiral liquid crystals have attracted considerable interest as they exhibit a good variety of modulated phases. We have synthesised a homologous series viz., 4-(4^!-n-alkoxy benzoyloxy) benzylidene-4^!!?1-(s)-methyl propoxy anilines, incorporating a terminal chiral centre, inorder to obtain better understanding of the relationship between molecular structure and appearance of SmC* phase in the molecules. It is observed that, in the present series the lower members upto butyl are pure nematogens, while pentyl to hexadecyl derivatives exhibit classical smectic as well as nematic mesophases. An additional smectic C* phase is observed in the middle octyl to dodecyl homologues. The homologues have been characterised by IR, NMR and DSC. Their mesomorphic properties have been compared with structurally related homologous series.     

Preparation and TSL studies in Tb activated LiMgPO4 phosphor

LiMgPO₄:Tb³⁺ phosphor was synthesized by solid state reaction. The thermally stimulated luminescence (TSL) glow curve of Tb doped LiMgPO₄ exhibits a main TSL peak at 170 °C with shoulders at 100 and 260 °C on either side of this peak. The TSL sensitivity of the phosphor was found to be about 2.5 times that of CaSO₄:Dy phosphor. TSL emission and photoluminescence (PL) studies show that Tb³⁺ ion acts as luminescence centre in this phosphor. The kinetic parameters, namely activation energy (E) and frequency factor (s) associated with the main glow peak have been determined using peak shape method. The activation energy and frequency factor obtained are 1.35 ± 0.03 eV and (6.53 ± 0.43) × 10¹⁴ s^?1 respectively. The paper discusses the dosimetric characteristics like dose response, fading, energy response and minimum detectable dose and results thereof.     

The compressible hybrid RANS/LES formulation using an additive operator

In this work, the compressible governing equations for the hybrid Reynolds-averaged/large-eddy simulations are formally derived by applying a hybrid filter to the Navier–Stokes equations. This filter is constructed by linearly combining the Reynolds-average (RANS) and large-eddy simulation (LES) operators with a continuous blending function. The derived hybrid equations include additional terms that represent the interactions between RANS and LES formulations. The relevance of these terms is investigated in flat-plate turbulent boundary layer simulations and indicate that these additional terms play a fundamental role in compensating for the turbulence that is neither modeled nor resolved in the transition region between RANS and LES. Results also show that when the additional terms are included, the calculations are not very sensitive to the blending function implemented in the hybrid filter. In the contrary, when these terms are neglected and a step function is implemented in the hybrid filter, nonphysical discontinuities are predicted in the flow statistics.