K-value predictions for the methane-ethane-propane system

Vapour-liquid equilibrium distribution coefficients at widely ranging pressures, temperatures, and compositions are essential data for process engineering calculations in the natural gas separation and petroleum processing industries. Computational methods for the accurate prediction of these data using only pure component properties are presented in this paper. The validity of the method has been tested for the system methane-ethane-propane at low temperatures and high pressures. The agreement between the predicted values and the corresponding experimental data taken from the literature illustrates the accuracy of the prediction method and justifies its applicability to working separation systems.     

Development of novel gastroretentive drug delivery system of gliclazide: hollow beads

Aim: The current communication deals with the development of hollow floating beads of gliclazide. The primary effect of this drug is to potentiate glucose-stimulated insulin release from pancreatic islet-β-cells by induction of a decrease in potassium efflux from these cells. Because of the poor aqueous solubility, its absorption is limited. Thus, an attempt was made to improve its release profile.

Methods: The hollow drug-loaded alginate beads in combination with low methoxyl pectin and hydroxypropylmethylcellulose (HPMC) were prepared by a simple ionotropic gelation method. The beads were evaluated for particle size and morphology using optical microscopy and scanning electron microscopy (SEM), respectively. Mucoadhesion test was done using goat stomach mucosal membrane. Release characteristics of the gliclazide-loaded hollow beads were studied in 0.1?N HCl (pH 1.2) and phosphate buffer (pH 5.8).

Results: The developed beads were spherical in shape with hollow internal structure and had a particle size in the range of 0.730?±?0.05 to 0.890?±?0.03?mm. The incorporation efficiency of alginate -pectin beads was higher than alginate -HPMC beads. The Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction analysis showed stable character of drug in the drug-loaded hollow beads and revealed the absence of any drug -polymer interactions. The beads remained buoyant for more than 12?h. The drug release from beads followed Fickian diffusion with swelling.

Conclusion: The preliminary results of this study suggest that the developed beads containing gliclazide could enhance drug entrapment efficiency, reduce the initial burst release and modulate the drug release.     

Magnetic-nanoparticle-doped carbogenic nanocomposite: an effective magnetic resonance/fluorescence multimodal imaging probe

A novel and facile approach is developed to synthesize a magnetic nanoparticle (iron oxide)-doped carbogenic nanocomposite (IO-CNC) for magnetic resonance (MR)/fluorescence imaging applications. IO-CNC is synthesized by thermal decomposition of organic precursors in the presence of Fe(3) O(4) nanoparticles with an average size of 6 nm. IO-CNC shows wavelength-tunable fluorescence properties with high quantum yield. Magnetic studies confirm the superparamagnetic nature of IO-CNC at room temperature. IO-CNC shows MR contrast behavior by affecting the proton relaxation phenomena. The measured longitudinal (r(1) ) and transverse (r(2) ) relaxivity values are 4.52 and 34.75 mM(-1) s(-1) , respectively. No apparent cytotoxicity is observed and the nanocomposite shows a biocompatible nature. In vivo MR studies show both T(1) and T(2) * contrast behavior of the nanocomposite. Fluorescence imaging indicates selective uptake of IO-CNC by macrophages in spleen.     

Behavior of dual ion beam sputtered MgZnO thin films for different oxygen partial pressure

Mg-doped ZnO (MgZnO) films were grown on p-Si (001) substrates by dual ion beam sputtering deposition system at a constant growth temperature of 600 °C for different oxygen partial pressure. The impact of oxygen partial pressure on the structural, electrical, elemental and morphological properties was thoroughly investigated. X-ray diffraction (XRD) spectra revealed that the deposited MgZnO films were polycrystalline in nature with preferred (002) crystal orientation. The peak of MgZnO (101) plane was reduced significantly as oxygen partial pressure was increased and disappeared completely at 80 and 100 % O₂. The maximum electron concentration was evaluated to be 5.79 × 10¹⁸ cm^?3 with resistivity of 0.116 Ω cm and electron mobility of 9.306 cm²/V s at room temperature, for MgZnO film grown with 20 % O₂. Raman spectra shows a broad peak at 434 cm^?1 corresponded to E ₂ ^high phonons mode of MgZnO wurtzite structure. The peak at 560 cm^?1 corresponded to the E₁ (LO) mode and was associated with oxygen deficiency in MgZnO films. Raman intensity at 560 cm^?1 reduced, on increasing oxygen partial pressure. A correlation between structural, electrical, elemental and morphological properties with oxygen partial pressure was also established.     

On mean residence times in flow systems

A widely accepted result of residence time theory namely mean residence time is equal to the system volume divided by the flow rate was first offered by Danckwerts[l] and later extended by Buffham[21 and Gibilaro[3] to more general cases. Taking a two section system it is argued and experimentally demonstrated that the above theoretical result is not universal. A possible implication of this result is that even for a single section system the above result may not hold in all the cases. This is also supported by experimental data on a single section system.     

Accurate CAD-Model Analysis of Multilayer Microstrip Line on Anisotropic Substrate

Computationally efficient equivalent isotropic relative permittivity of the multilayer microstrip line on the uniaxial anisotropic substrate for 0 < w/h ≤ 10, anisotropic ratio0.5 ≤ n ≤ 3.0. Model has accuracy 0.5% against the full-wave method. It computes effective relative permittivity and characteristic impedance of microstrip on composite anisotropic substrates with deviation 4.5% respectively against the EM- software HFSS. Dispersion in multilayer anisotropic substrate microstrip up to mm wave range with high accuracy against the results of HFSS. The proposed models could be incorporated in the computer aided design for development of the components on the uniaxial anisotropic substrates.     

Electrochemical hydrogen evolution and storage studies on bismuth nano hexagons

Bismuth nano hexagons were synthesized using potentiostatic electrodeposition and studied for their performance towards electrochemical hydrogen storage and evolution. Regular hexagons with edge length ≈ 500 nm and thickness ≈ 80 nm were observed in scanning electron microscopy (SEM). X-ray diffraction (XRD) pattern indicates the presence of poly-crystalline bismuth and bismuth oxide in rhombohedral and cubic phases respectively. X-ray photoelectron spectroscopy (XPS) studies further confirm the presence of two phases of bismuth i.e. elemental bismuth and bismuth (III) oxide. Results indicate that these nano hexagons show good hydrogen ion (H⁺) storage and successive hydrogen gas (H₂) evolution characteristics.     

Selective deposition of Pd nanoparticles in porous PET membrane for hydrogen separation

Hydrogen purification based on Pd deposition in porous polymeric membranes show promising results for hydrogen permeability and selectivity. It is due to high absorption property of Pd nanoparticles. In this work, gas permeability of carboxylic group functionalized Polyethylene terephthalate (PET) membranes with different time of functionalization have been examined. It has been found that PET membrane having more –COOH group shows higher selectivity for Hydrogen (H₂). Further to improve the selectivity, these carboxylated PET membranes dipped in Pd nanoparticles solution for 6 h and found more selective for H₂ in comparison to Carbon dioxide (CO₂) and Nitrogen (N₂). As the carboxylation increases selectivity of H₂ improves drastically in the beginning and nearly get saturated after 24 h. Similar trend has been observed for these membranes after Pd nanoparticles deposition. Fourier transform infrared spectroscopy (FTIR) spectra of these membranes revealed that intensity of peaks related to –COOH group at 2968 cm^?1 & 1716 cm^?1 increases with functionalization time. Field Emission Scanning Electron Microscopy (FESEM) was used to study the surface morphology of membranes.