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Sayem Alam M.,CSIR - Central Leather Research Institute | Sayem Alam M.,Academy of Scientific | Mandal A.B.,CSIR - Central Leather Research Institute
Journal of Molecular Liquids | Year: 2015

In this investigation, we have studied the micellization of non-ionic surfactant, Triton X-114 (by surface tension measurement) and cationic gemini surfactant, pentanediyl-1,5-bis(dimethylcetylammonium bromide) (16-5-16) by surface tension, conductivity and dye solubilization methods and the clouding phenomena of mixed surfactant (non-ionic Triton X-114 + cationic gemini 16-5-16) system in aqueous solution. The critical micelle concentration (CMC) of Triton X-114 and 16-5-16 were measured and their surface properties and thermodynamics were evaluated. In aqueous solution, non-ionic surfactant, Triton X-114 undergoes phase separation or cloud point (CP). Herein, we also report the influence of additives (e.g., electrolytes, sugars, amino acids, etc.) on the CP of Triton X-114 in aqueous solutions. The CP showed a concentration dependent variation in the absence of any added compound (additives). With the addition of additives, the CP values were found to decrease and increase. It is found that the CP of pure Triton X-114 is concentration dependent; and the presence of gemini surfactant (16-5-16) increases the CP. However, all additives in the presence of the gemini surfactant (i.e., Triton X-114 + 16-5-16 system) decrease the CP. The results are discussed by taking into consideration the nature of the additives. The thermodynamic parameters are also evaluated at CP. © 2015 Elsevier B.V. All rights reserved.

Pasupuleti S.B.,Flemish Institute for Technological Research | Pasupuleti S.B.,Indian Institute of Chemical Technology | Pasupuleti S.B.,Academy of Scientific | Srikanth S.,Flemish Institute for Technological Research | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2015

Three microbial fuel cells (MFC) with dual gas diffusion cathode design were operated individually in different operation modes, viz., batch (MFC-BM), semi-continuous (MFC-SCM) and continuous (MFC-CM), using dark fermentation effluent (DFE). MFC-BM depicted lower power density (PD, 1.31 ± 1.75 mW/m2) due to the electron losses and mass transfer limitations, while, MFC-SCM (19.06 ± 2.01 mW/m2) and MFC-CM (15.53 ± 2.51 mW/m2) depicted higher PD. Though MFC-SCM showed higher power output, the energy conversion efficiency (ECE) was higher during MFC-CM (9.85 ± 1.02%) operation over MFC-BM and MFC-SCM operations. Henceforth, the stacking approach was carried out in continuous mode operation using DFE which showed a very good power output along with treatment efficiency. Stack mode operation was carried out at decreasing external loads to increase the overall power output as well as the electron delivering ability of the biocatalyst. Stack MFC depicted its maximum PD (3163 mW/m3; 19.79 mW/m2), across 2 kω of external resistance (Rex) along with the treatment efficiency of 80 ± 2%. Further decrement in Rex to 1 kω has resulted in lower and unstable PD, due to the inability of the biocatalyst to meet the electron requirement by the circuit. A detailed understanding of the stack MFC was made in terms of electrogenesis, electron discharge, coulombic and energy conversion efficiencies as well as the bioprocess parameters. © 2015 Hydrogen Energy Publications, LLC.

Dwivedi V.,CSIR - Central Electrochemical Research Institute | Hari Babu M.,CSIR - Central Electrochemical Research Institute | Kant R.,CSIR - Central Electrochemical Research Institute | Sridhar Reddy M.,CSIR - Central Electrochemical Research Institute | Sridhar Reddy M.,Academy of Scientific
Chemical Communications | Year: 2015

A highly general palladium catalysed regioselective hydroalkynylation of ynamides for versatile enamide building blocks with an alkyne tether is achieved with an N-substitution dependent stereoselectivity switch under very mild reaction conditions. © 2015 The Royal Society of Chemistry.

Chudasama N.A.,Indian Central Salt and Marine Chemicals Research Institute | Siddhanta A.K.,Indian Central Salt and Marine Chemicals Research Institute | Siddhanta A.K.,Academy of Scientific
Carbohydrate Research | Year: 2015

In a facile synthesis agarose was amphoterically functionalized to afford nano-sized agarose amino acids, aminoagarose succinate half-esters (AAE) containing one pendant carboxyl group. Nano-sized AAEs (<10nm; DLS) were characterized and they had three various degrees of substitution [overall DSs 0.88, 0.89 and 0.96], both the amino and half-ester groups were placed on C-6 positions of the 1,3 beta-d-galactopyranose moieties of agarose backbone (13C NMR). AAEs performed like large protein molecules exhibiting pH-responsive structural variations (optical rotatory dispersion), presenting a mixed solubility pattern like random coil (soluble) and aggregate (precipitation) formations. Circular dichroism studies showed their pH-dependent associative interactions with bovine serum albumin, which indicated complexation at acidic and basic pHs, and decomplexation at pH6.8 with AAE (DS 0.96). Thus, these nano-sized AAE based systems may be of potential utility in the domains demanding the merits of preferential protein bindings e.g. pH-responsive cationic/anionic drug carrier, separations or chiral sensing applications. © 2015 Elsevier Ltd. All rights reserved.

Hussain N.,CSIR - Central Electrochemical Research Institute | Hussain N.,Academy of Scientific | Borah A.,Academy of Scientific | Borah A.,CSIR - Central Electrochemical Research Institute | And 9 more authors.
New Journal of Chemistry | Year: 2015

A new strategy for in situ synthesis of palladium nanoparticles (Pd NPs) decorated on reduced graphene oxide (rGO) nanosheets with controlled size and shape is reported. This strategy was designed as three processes in one pot, namely, (a) reduction of graphene oxide, (b) formation of Pd NPs on the rGO nanosheets and (c) simultaneous reduction of olefin. In this synthesis process, a hydrogen atmosphere was used to develop the Pd NPs-rGO nanocatalyst, which is reusable and easily separable. The influence of the size and morphology of the Pd-rGO-H2 catalyst on the catalytic activity in the Suzuki cross-coupling reaction was investigated by comparing with other catalysts, Pd-rGO-As and Pd-rGO-Gl, and they were synthesized by different reducing agents, ascorbic acid and glucose, respectively. The catalysts were characterized by electron microscopy (HRTEM, SEM), FT-IR, XRD and XPS. The Pd-rGO-H2 catalyst was found to possess excellent catalytic activity and recyclability in the Suzuki cross-coupling reaction under mild reaction conditions. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015.

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