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.     

Virgin response of field induced microwave absorption in the high Tc ceramic superconductor BSCCO — RSJ model

Field induced microwave absorption is recorded at low fields (<20mT) in a high T_c ceramic superconductor (Bi,Pb)---Sr---Ca---Cu---O, after cooling in zero field to 54,77 and 90 K at 9.9 GHz and to 77K at 36.4 GHz. The results are discussed in conjunction with the dc magnetization data obtained on the same sample. It is argued that the observed features do not follow the predictions of the flux flow model while they give qualitative evidence in support of the resistively shunted Josephson junction model.     

Ferromagnetic resonance in amorphous systems: Dependence of the relaxation parameter on temperature (magnetization)

We have studied the uniform mode ferromagnetic resonance in the amorphous systems Metglass 28226A, 2826B, 2826 over the temperature range 77–430 K. The data have been analysed in terms of the Gilbert Equation. The g-values are very similar to those of crystalline permalloy. The relaxation parameters λ, are of the order of 10⁸ s^?1 and exhibit an interesting temperature dependence. In particular, for $\text{T}\text{T}{}_{\mathrm{c}}\text{?0.5, λ}$ is simply proportional to the static saturation magnetization M_s. The present results are compared with those obtained on crystalline samples of the 3-d transition metals and their alloys.     

Hall effect in amorphous magnetic materials — METGLAS 2826 and 2826B

Hall effect measurements on the ferromagnetic amorphous materials, Metglas 2826 and 2826B, indicate that they are rather similar to crystalline soft magnetic materials. The extra-ordinary Hall coefficient R_s is found to be 1.4 × 10⁴?² (m³/As), where, ?, is the electrical resistivity, and is in reasonable agreement with the predictions of theory. On the other hand, though unexpected, the ordinary Hall coefficient in all the amorphous alloys we have studied turns out to be of the order of 7 × 10^?10 (m³/As).     

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.     

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...     

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.