@article { ISI:000299291900033, title = {Nanocomposite silica surfactant microcapsules by evaporation induced self assembly: tuning the morphological buckling by modifying viscosity and surface charge}, journal = {Soft Matter}, volume = {8}, number = {6}, year = {2012}, month = {DEC}, pages = {1955-1963}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Nanocomposite microcapsules of silica and surfactants have been synthesized using evaporation induced self-assembly through spray drying. It was established using electron microscopy and small-angle neutron/X-ray scattering experiments that the viscosity of the virgin dispersion and surface charge of colloidal components play a significant role in the buckling of spray droplets during drying. Hollow spherical grains are realized at relatively low viscosity and higher surface charge while mushroom like grains manifest at higher viscosity and lower surface charge. In the intermediate conditions, deformed doughnut shaped microcapsules are obtained. Scattering experiments establish the presence of the organization of micelle like aggregates of surfactants in the dried grains and also corroborate with the observations from electron microscopy. A plausible mechanism regarding the chronological pathways of morphological transformation is illustrated. Computer simulation, based on buckling of an elastic shell using a surface evolver, has been attempted in order to corroborate the experimental results.

}, issn = {1744-683X}, doi = {10.1039/c1sm06964k}, author = {Sen, D. and Bahadur, Jitendra and Mazumder, S. and Verma, G. and Hassan, P. A. and Bhattacharya, S. and Vijai, K. and Doshi, Pankaj} } @article { ISI:000355702900052, title = {Mesoporous TUD-1 supported indium oxide nanoparticles for epoxidation of styrene using molecular O-2}, journal = {RSC Advances}, volume = {5}, number = {58}, year = {2015}, month = {MAY}, pages = {46850-46860}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Activation of molecular O-2 by metal or metal oxide nanoparticles is an area of recent research interest. In this work, for the first time, we report that indium oxide nanoparticles of \<3 nm size dispersed on mesoporous silica (TUD-1) can activate molecular O-2 and produce styrene epoxide with a selectivity of 60\% and styrene conversion around 25\% under mild conditions. It is found that neither indium oxide nor TUD-1 themselves respond to the styrene epoxidation reaction. The computational studies provide evidence that an oxygen molecule is highly polarized when it is located near the interface of both surfaces. The kinetic study shows that the reaction is of pseudo-first order and that the activation energy for styrene conversion is 12.138 kJ mol(-1). The catalysts are recyclable for up to four regeneration steps, with the styrene conversion and styrene epoxide selectivity almost unchanged.

}, issn = {2046-2069}, doi = {10.1039/c5ra03400k}, author = {Rahman, Sumbul and Farooqui, Saleem A. and Rai, Aditya and Kumar, Rawesh and Santra, Chiranjit and Prabhakaran, Vinod C. and Bhadu, Gopala Ram and Sen, Debasis and Mazumder, S. and Maity, Sudip and Sinha, Anil K. and Chowdhury, Biswajit} } @article { ISI:000365602800014, title = {Study on fused/cast AZS refractories for deployment in vitrification of radioactive waste effluents}, journal = {Journal of Nuclear Materials}, volume = {467}, number = {1}, year = {2015}, month = {DEC}, pages = {144-154}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Fused/cast Al2O3-ZrO2-SiO2 (FC-AZS){\textquoteright} is being considered as {\textquoteleft}glass contact refractory{\textquoteright} within ceramic melters, to be used for nuclear waste immobilization. Microstructural analyses reveal random distributions of baddeleyite (ZrO2) within aluminosilicate (Al2SiO5) matrix. Al-27 and Si-29 NMR data suggest that within aluminosilicate matrix Al occurs in both 4- and 6-fold co-ordinations whereas Si prefers a 4-fold environment. Polydispersity of pores has been studied with small-angle neutron scattering (SANS) technique. Corrosion rates of FC-AZS within 6 M HNO3, simulated wastes (500 h exposure), and borosilicate melt (975 degrees C, 800 h exposure) are found to be 0.38 x 10(3) mu my(-1), 0.13 x 10(3) mu my(-1) and 4.75 x 10(3) mu my(-1) respectively. A comparison of chemical interaction data clearly suggests that FC-AZS exhibits better chemical durability than AZC refractory (Al2O3-ZrO2-Cr2O3, also used for similar purpose). Thermal cycling studies indicate that FC-AZS retains structural integrity (including compressive strength and density) even up to 20 cycles. (C) 2015 Elsevier B.V. All rights reserved.

}, keywords = {Interaction between refractory material and hazardous liquid, Nuclear waste immobilization, Vitrification melter}, issn = {0022-3115}, doi = {10.1016/j.jnucmat.2015.09.019}, author = {Sengupta, Pranesh and Mishra, Raman K. and Soudamini, N. and Sen, D. and Mazumder, S. and Kaushik, Chetan P. and Ajithkumar, Thalasseril G. and Banerjee, K.} } @article {45637, title = {Highly stable In-SBA-15 catalyst for vapor phase Beckmann rearrangement reaction}, journal = {Microporous and Mesoporous Materials}, volume = {234}, year = {2016}, month = {NOV }, pages = {293-302}, type = {Article}, abstract = {

The Indium doped SBA-15 material was prepared by sol-gel method and tested for vapor phase Beckman rearrangement reaction. Among three indium loading, In/Si ratio of 2/100 was found as an optimum composition in terms of caprolactam selectivity (100\%) and cyclohexanone oxime conversion (100\%). The catalysts were characterized by N-2 adsorption, small-angle X-rays/neutron scattering (SAXS/SANS), XRD, FESEM, HRTEM, EDX, UV, FTIR and NH3-TPD techniques. In-situ SANS experiment was performed on the adsorption of CO2 to detect the micropores in the mesopore wall. All catalysts samples have highly ordered hexagonal structure with well dispersed indium in the silica matrix. The fine tuning of weak and strong acid sites were found in indium doped SBA-15 (In/Si = 2/100) catalyst. The same catalyst showed optimum catalytic performance, high space time yield 114.4 mol/h/g(cat) and high stability till 6 h of reaction without deactivation. The micro-kinetic analysis showed that there were no external and internal diffusion limitations in the SBA-15 catalyst. The reaction mechanism of Beckmann rearrangement over In-SBA-15 has been elucidated. (C) 2016 Elsevier Inc. All rights reserved.

}, keywords = {e-Caprolactam, In-situ SANS, indium, SAXS, SBA-15}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2016.07.024}, author = {Kumar, Rawesh and Shah, Sneha and Bahadur, Jitendra and Melnichenko, Yuri B. and Sen, Debasis and Mazumder, S. and Vinod, Chathakudath P. and Chowdhury, Biswajit} } @article {45675, title = {Structure and short time degradation studies of sodium zirconium phosphate ceramics loaded with simulated fast breeder (FBR) waste}, journal = {Journal of Nuclear Materials}, volume = {487 }, year = {2017}, month = {APR}, pages = {5-12}, type = {Article}, abstract = {Sodium zirconium phosphate (NZP) ceramics have been prepared using conventional sintering and hot isostatic pressing (HIP) routes. The structure of NZP ceramics, prepared using the HIP route, has been compared with conventionally sintered NZP using a combination of X-ray diffraction (XRD) and (P-31 and Na-23) nuclear magnetic resonance (NMR) spectroscopy techniques. It is observed that NZP with no waste loading is aggressive toward the steel HIP -can during hot isostatic compaction and significant fraction of cations from the steel enter the ceramic material. Waste loaded NZP samples (10 wt\% simulated FBR waste) show significantly low can -interaction and primary NZP phase is evident in this material. Upon exposure of can -interacted and waste loaded NZP to boiling water and steam, P-31 NMR does not detect any major modifications in the network structure. However, the Na-23 NMR spectra indicate migration of Na+ ions from the surface and possible re -crystallization. This is corroborated by Small -Angle Neutron Scattering (SANS) data and Scanning Electron Microscopy (SEM) measurements carried out on these samples.}, doi = {10.1016/j.jnucmat.2017.01.054}, author = {Ananthanarayanan, A. and Ambashta, R. D. and Sudarsan, V. and Ajithkumar, T. and Sen, D. and Mazumder, S. and Wattal, P. K.} }