Hydrocarbon group type analysis of petroleum heavy fractions using the TLC-FID technique

Hydrocarbon group type analysis is important in all conversion processes and in preparation of feed for these conversion processes so as to learn the selectivity of the different type of catalysts for product yield and quality. The use of the Mark 5 Iatroscan detector and the method reported here allowed for a rapid and quantitative hydrocarbon group type analysis of petroleum residues without prior separation of asphaltenes. SARA type analyses of petroleum residues have been performed by a three stage development using n-hexane, toluene and DCM (95%):MeOH (5%). The standard deviation and coefficient of variation in repeated measurements by this method were as low as 0.65 wt% or less and 3.5 wt% or less, respectively. The time required for analysis of 10 samples could be as short as 90 min.     

Hydrotropic Enhancement of Rate of Ninhydrin‐α‐Amino Acid Reaction: A Kinetic Study

The kinetics of ninhydrin‐α‐amino acid (alanine, phenylalanine, and valine) reaction have been studied in the absence and in the presence of a common hydrotrope, sodiumbenzoate. A strong enhancement in the rate of reaction has been observed in the presence of the hydrotrope above its minimal hydrotrope concentration (MHC). The order of reaction in ninhydrin was always found to be unity while that in amino acid decreases from unity to zero at higher [Aminoacid]. A mechanism consistent with kinetic data and involving the formation of a mixed aggregation assemblies between amino acid and hydrotrope has been proposed.     

On shadowing property for inverse limit spaces

We study here the G-shadowing property of the shift map σ on the inverse limit space X _f, generated by an equivariant self-map f on a metric G-space X.      

Design,optimization and critical analysis of graphene based surface plasmon resonance sensor for DNA hybridization

Optical and Quantum Electronics - We have investigated the potential of using the E-field induced birefringence for improving the sensitivity of uniaxial anisotropic slab waveguide sensor based on...     

Field-induced microwave absorption in Fe3O4 nanoparticles and Fe3O4/polyaniline composites synthesized by different methods

Three kinds of nanoscale powders containing Fe₃O₄ nanoparticles (NPs) have been studied by ferromagnetic resonance (FMR): (i) Fe₃O₄ NPs grown and then covered with polyaniline (PANI), (ii) unclad Fe₃O₄ NPs, and (iii) Fe₃O₄ NPs grown “in situ” with the PANI. In every case, there is no low field microwave absorption, rather a single FMR line is observed. However, the half-power widths are of order of 1 kOe presumably due to a distribution of internal fields. For type I particles with a low concentration (below 40%) of Fe₃O₄, the observed resonance fields (H_r) are close to those expected for spheres with negligible magnetocrystalline anisotropy. For all other cases, H_r values are significantly lower. Such shortfalls can be roughly understood by invoking dipolar interactions between the grains, stresses frozen in grains during manufacture (method III), as well as anisotropy fields when the specimens are prepared in an aligning field.     

On the use of ferromagnetic resonance to determine the ferromagnetic-spin glass transition line —Temperature dependence of linewidths

We report temperature dependence of FMR linewidths (Γ) for a set of amorphous Fe_yNi_80?yP₁₄B₆ alloys. The linewidths show maxima as a function of T. However, the temperatures (T_m) corresponding to the maxima not only differ from the low field freezing temperatures reported earlier but also depend on microwave frequency. We contend that the T_m ′s should not be used to identify the zero-field ferromagnetic-spin glass transition line.     

Low-field microwave magnetoabsorption in the cuprate superconductors

We review results on the low-field microwave magnetoabsorption (LFMMA) in granular samples of YBCO and BSCCO. First, we show that the virgin response (increase in absorption on first application ofH) obeys a universal form (ΔP/α)=(1+H ₀/H)^?1. Interpreting this in conjunction with de magnetization isotherms on the same samples, we demonstrate that the data support a model in which the LFMMA arises from field dependent reduction in the critical currents of the weak links in the sample surface. Next, we present examples of the variety of hysteresis loops obtained on subsequent field cycling and interpret them in terms of the universal form provided thatH is replaced by an effective valueH _eff. Attempts are made to delineate the various terms appearing inH _eff.     

The impact of unbounded swings of the forcing term on the asymptotic behavior of functional equations

Necessary and sufficient conditions have been found to force all solutions of the equation

In vitro antimicrobial evaluation,effects of halide concentration and hemolysis study of silver-N-heterocyclic carbene complexes

Research on Chemical Intermediates - The morpholine containing silver complexes were screened for the zone of inhibition, MIC determination, and longevity studies against bacterial growth. The most...     

Correlation of size and oxygen bonding at the interface of Si nanocrystal in Si–SiO2 nanocomposite: A Raman mapping study

Raman spectroscopy/mapping is used to investigate the variation of Si phonon wavenumbers, i.e., lower wavenumber (LW ~ 495–510 cm⁻¹) and higher wavenumber (HW ~ 515–519 cm⁻¹) phonons, observed in Si–SiO₂ multilayer nanocomposite (NCp) grown using pulsed laser deposition. Sensitivity of Raman spectroscopy as a local probe to surface/interface is effectively used to show that LW and HW phonons originate at surface (Si–SiO₂ interface) and core of Si nanocrystals, respectively. The consistent picture of this understanding is developed using Raman spectroscopy monitored laser heating/annealing and cooling experiment at the site of the desired wavenumber, chosen with the help of Raman mapping. Raman spectra calculations for Si₄₁ cluster with oxygen and hydrogen termination show strong mode at 512 cm⁻¹ for oxygen terminated cluster corresponding to the vibration of surface Si atoms. This supports our attribution of LW phonons to be originating at the Si–SiO₂ surface/interface. These results along with XPS show that nature of interface (oxygen bonding) in turn depends on the size of nanocrystals and LW phonons originate at the surface of smaller Si nanocrystals. The understanding developed can conclude the ongoing debate on large variation in Si phonon wavenumbers of Si–SiO₂ NCps in the literature. Copyright © 2015 John Wiley & Sons, Ltd.