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1

Kinetics and mechanism of electron transfer to pyridinium chlorochromate (VI) from sulfur containing amino acid, L-cysteine in aqueous and micellar media

Senapati S., Das S., Mohanty P., Patnaik A.K.

Polish Journal of Chemical Technology

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2011

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Vol. 13, nr 2

6-10

EN

The electron transfer reaction of L-cysteine (RSH) with pyridinium chlorochromate (PCC) has been studied spectrophotometrically over the range 2.0 ≤ 10^3 [RSH] ≤ 6.0; 0.01 ≤ [H+] ≤ 0.2; 298 ≤ T ≤ 318 K and I = 0.3 mol dm-3 (NaClO4). The electron transfer reaction has also been carried out in the presence of anionic, cationic and neutral micelle. The reaction in acid medium is strongly catalyzed by changing [SDS]T (sodium dodecyl sulfate) up to 3 × 10-2 mol dm-3, beyond this concentration of SDS, the rate is retarded. The cationic and neutral micelle has a small effect on the rate. ΔH≠ (kJ mol-1) and ΔS≠ (JK-1 mol-1) values for the k1 and k2 paths are 30.20 ± 0.25, -159.65 ± 0.83 and 29.60 ± 0.62, -127.09 ± 2.17, respectively. The negative activation entropy is indicative of the ordered transition state for the electron transfer reaction. Formation of 2-amino-3-(2-amino-2-carboxy-ethyl) disulfanyl-propanoic acid as product is strongly supported by IR spectra.

2

Kinetics and Mechanism of Complex Formation between O-Bonded Pentaammine(valinato/prolinato)cobalt(III) Ions and Nickel(II) in Aqueous Medium

Dash A., Brahma G., Mohanty P., Das R.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 7

987-995

EN

The kinetics of reversible complexation of Ni(OH2)6 2+ with oxygen-bonded valinato/prolinatocobalt( III) substrates, (NH3)5Co(val/pro)3+ have been investigated by stopped flow technique at 25_C, 6.1_ pH_6.70 and I = 0.3 mol dm-3. The formation of binuclear species, [(NH3)5Co(val/pro)Ni]4+, occured via the reaction of Ni(OH2)6 2+ with deprotonated (amine and imine functions of valine and proline, respectively) form of the cobalt(III) substrates, (NH3)5Co(val/pro)2+. The results indicate the formation of mono-bonded binuclear species through entry of the imine/amine functions into the coordination sphere of Ni(II) with Ni-OH2 bond dissociation is limiting (Id mechanism). The binuclear species exist in dynamic equilibrium involving the mono-dentate and chelated forms with chelated forms predominating. The small values of dissociation rate constants, despite the intrinsic electrostatic repulsion between the like charge centers, also support the chelate nature of the binuclear species.

3

Kinetics and Mechanism of Complex Formation between Pentamminesuccinatocobalt(III) and Gallium(III)

Gouri S., Mohanty P.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 10

1221-1228

4

Application of tomographic reconstruction techniques to synthetic cross-hole seismic data

Mohanty P., Siddique F.

Acta Geophysica Polonica

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2002

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Vol. 50, nr 3

381-393

EN

Three reconstruction techniques are applied to synthetic travel time data using cross-hole geometry in order to image the velocity structure. Algebraic Reconstruction Technique (ART), Simultaneous Interactive Reconstruction Technique (SIRT) and Ray Projection Technique (RAYPT) have been applied to three different geological models. The reconstructed images of these models provide comparative match with the delineation of anomalous zone with some background noise. However, because of limited coverage in viewing angle, a few reconstructed images do not provide reliable velocity structure. Out of these three techniques, the RAYPT provides reasonably good images of the synthetic cross-hole data.

5

Seismic resolution over coal seams: a numerical study

Mohanty P., Phadke S., Bhattacharya B.

Acta Geophysica Polonica

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2000

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Vol. 48, nr 2

215-222

EN

Processing tool like migration is rarely applied to high resolution shallow coal seismic data. The improvement of stacked section by using migration is so far only marginal. In addition, it takes tong computing time to perform migration on PC based system commonly used for day-to-day shallow high resolution seismic data processing. With the advent of powerful and inexpensive workstation, migration is carried out on post stack as well as pre stack data. The present study is an example of migration technique applied to zero-offset time sections generated for three different geological models. The geological models incorporate coalseam discontinuities like fault, fold and feeder dyke commonly encountered in the coal bearing formations of eastern India. In order to select a suitable migration scheme, both finite-difference depth migration and frequency wavenumber (f-k) phase shift time-migration are applied to the zero-offset data generated for these models. Depth migration scheme has significantly improved the imaging conditions compared to the f-k phase shift time-migration. Besides, the depth migration restored the lateral continuity of the fault and delineated the small scale structural features clearly in the case of feeder dyke and fold.