Welcome to http://publicationslist.org/tania_dey Tania Dey comes from a Chemistry background. She earned her PhD in 2002 and since then has worked as a Research Scientist in North America. Her research expertise encompasses various interdisciplinary areas of Colloid/Polymer Science, Advanced Materials and Nanotechnology [http://ca.linkedin.com/pub/dir/Tania/Dey]. She was awarded Marquis Who's Who in America 2009, for her research accomplishments. She also serves as an Associate Editor for a reputed Materials Science journal and as a peer-reviewer for several other scientific journals.
Abstract: Nanotechnology is a highly inter- and multi- disciplinary application oriented research area. Not only does it find its use in nanomedicine, solar cells, sensor development and so on, but can also be effectively utilized to prevent water pollution. Nanostructured materials such as magnetic nanoparticles, carbon nanotubes, silver-impregnated cyclodextrin nanocomposites, nanostructured iron-zeolites, carbo-iron nanomaterials, photocatalytic titania nanoparticles, nanofiltration membranes and functionalized silica nanoparticles can be employed in water treatment to remove heavy metals, sediments, chemical effluents, charged particles, bacteria and other pathogens. This edited book comprises several review-style chapters written by world experts. The chapters are devoted to each of these nanotechnology based approaches: basic principles, practical applications, recent break-through and limitations associated with it. The last chapter covers the environmental risks of applying engineered nanomaterials for water purification. The wealth of information and insight offered in this book will be appealing to scientists and researchers over a wide range of disciplines.
Abstract: This book describes two main categories of adsorption, differences between adsorption and absorption, thermodynamic parameters associated with adsorption, factors affecting the adsorption process, properties of surface films, some application areas, and the assumptions, derivations, limitations and numerical problems related to different kinds of adsorption isotherms, namely Freundlich?s, Langmuir, B.E.T. and Gibb?s adsorption isotherm.
This book is a concise lecture-style study guide, not a textbook. The knowledge and information offered in this study guide will be particularly useful for undergraduate chemistry students (second year) who are already introduced to the topic and are preparing for their exams now, as well as for the advanced level students and instructors in physical chemistry and interdisciplinary areas, who need a refresher.
Abstract: The micellar behavior of Sodium Deoxycholate (NaDC), a bile salt in presence of a neutral water soluble polymer Poly(vinylpyrrolidone) (PVP) has been investigated at four different temperatures (10 C-40 C) using conductometric, tensiometric, viscometric and fluorometric methods. NaDC is found to associate co-operatively with the polymer beyond a critical concentration, saturate the polymer completely and then undergo micellization at a higher concentration. The counter-ion binding capacity to the micelles is considerably reduced in presence of PVP. The thermodynamic properties of micellization and interfacial adsorption depend on the polymer concentration and the entropic contributions are observed to control the complexation process. The NaDC-PVP aggregate exhibits polyelectrolytic behavior. The aggregation number (N) and polarity index (I1/I3) of the NaDC-PVP mixed entities have been explored by pyrene fluorescence probing technique. The values of N and I1/I3 are found to be affected by [PVP] and temperature: the N values decrease with temperature while those of I1/I3 show increasing trend. The dependence of N and I1/I3 values on [PVP] and temperature reveal interesting insights into the NaDC-PVP complexation phenomenon.
Abstract: A sequential combination of thermal oxide growth, photolithography, buffered hydrogen fluoride (BHF) etch, sputter deposition and lift-off process were used to produce square-shaped nano-islands of gold and silica grid patterns on a doped silicon support. This nanofabricated surface was characterized by profilometry, optical microscopy, atomic force microscopy (AFM) and cyclic voltammetry (CV). The height difference between gold and silica was tailored to be ~ 35 nm. This kind of chip can be used as bio-sensors for detecting various metalloproteins grafted on gold islands, as well as caged analyte molecules inside the protein, from their corresponding electrochemical read-out.
Abstract: Teachers can highlight the application and importance of a particular topic, to make courses more meaningful. Polymers are a part of our daily life. This article elucidates why students should take interest in 'polymer viscosity'. Some viscosity based nomenclatures are introduced at the beginning. It is being shown how some practically important parameters such as molecular weight of polymer, average end-to-end distance of polymer and degree of branching in polymer can be derived from the intrinsic viscosity values. Some interesting experiments are suggested at the end, which can nurture curiosity and critical thinking among students and improve correlation between courses and real world things.
Abstract: This paper reports the fabrication of a photonic crystal made of hydrogel-coated colloidal nanoparticles, which can act as an optical sensor in visible and nearinfrared region triggered by temperature. The synthetic scheme involves silanization of silica nanoparticles followed by radical-initiated precipitation polymerization forming a thermoresponsive polymer coating. These core-shell nanostructures self-assemble to produce colloidal crystalline array (CCA). The main advantages of selfassembly approach are experimental simplicity, possibility of 3D assembly and inexpensive mass production. Photon correlation spectroscopy results revealed a very interesting new phenomenon of showing a distinct break near the lower critical solution temperature along with a set of twostep curves, in the plot of mean hydrodynamic radius vs. temperature, which can be attributed to the breakage of two different types of hydrogen-bonding. The lattice parameters of these CCAs and hence their sensor properties can be effectively tuned by varying the core-size and temperature, which in turn changes the composite particle size as well as shape and hence volume fraction. In Reflectance measurements, the position of the stop-band was found to be directly proportional to the core-size, whereas the appearance of a second diffraction peak was correlated to the nonspherical nature of the nanocomposites supported by atomic force microscope images and possibly due to the existence of a second phase. The occurrence of such highorder multiple Braggâs diffraction peak certainly opens a new door towards nanophotonic sensor devices.
Abstract: Platinum nanoparticles prepared by the interaction of Chloroplatinic acid (H2PtCl6). H2O and hydrazine hydrateà (N2H4.H2O) in water-in-oil microemulsion [Polyoxyethylene-4-dodecylether (C12E4) + Cyclohexaneà (C6H12) + Water (H2O)] in the absence and presence of poly(N-vinylpyrrolidone) (PVP) and Polyethylene Glycol (PEG) have been characterized using X-Ray diffraction (XRD), electron diffraction and transmission Electron Microscopy (TEM) techniques. Platinum nanoparticles adsorbed on alumina converted CO to CO2 at much lower temperature (245°C) compared to 325°C when pure alumina was used as catalyst. The catalytic activity of the synthesized nanoparticles in microemulsion containing PVP, examined in terms of CO to CO2 conversion reaction as a function of temperature exhibit higher catalytic efficiency compared with those synthesized in the microemulsion without PVP and microemulsion-PEG systems.
Abstract: This paper reports the formulation of a low-cost vinyl ester-based composite resin suitable for liquid
molding, which has significantly lower volatile organic compound emission associated with it. Methacrylated fatty
acid comonomers were used to replace the conventional yet environmentally hazardous reactive diluent, styrene.
The chain length of these fatty acids played a key role in obtaining better viscosity, as it was proved to affect
two interplaying factors: intermolecular friction and hydrogen bonding. The thermomechanical performance was
greatly affected by the chain length of the fatty acids as well as the crosslink density of the polymer networks. A
carbon number of 6 to 8 was good enough in optimizing the viscosity parameter suitable for handling; the dynamic mechanical analysis values, namely glass transition temperature and storagemodulus, were in the range 66â121 â¦C and 0.97â2.8GPa, respectively, as the carbon number was varied from 4 to 16, making the material suitable for various applications. Microstructures obtained from scanning electron microscopy results were correlated with polymer properties to obtain a better insight into these polymer networks.
Abstract: ATRP (atom transfer radical polymerization) approach was employed to synthesis polymer-coated
magnetite nanoparticles. These particles had an average diameter of 7.1 nm and a narrow size
distribution. Characterization was performed using various techniques like Transmission Electron
Microscopy (TEM), Ultraviolet-Visible spectroscopy (UV-vis), Fourier Transform Infrared spectroscopy
(FTIR), Atomic Force Microscopy (AFM), and Vibrating Sample Magnetometry (VSM). The
challenge was to obtain a thin shell and discrete particles in an unagglomerated state. Several
factors like presence/choice of solvent, monomer-to-initiator concentration and structure of initiator
were found to play a key role in this study. Attempts have been made to tailor the polymer shells
by end-functionalization. This work has an enormous biomedical application potential.
Abstract: The methods of microcalorimetry and tensiometry have been employed for the assessment of the thermodynamics of micellization and surface chemical behavior of the nonionic surfactant, p-tert-octylphenoxypolyoxyethylene ether (TritonX-100) in aqueous medium. The critical micellar concentration (CMC) obtained at different temperatures by both the methods have been compared. The energetic parameters (Gibbs free energy, enthalpy, entropy and heat capacity) of micellization have been evaluated from the results along with the interfacial adsorption parameters according to physicochemical concepts and relations. The steady state fluorescence quenching method has been employed for the determination of the aggregation number at different temperatures.
Abstract: The micellar properties of sodium glycodeoxycholate (NaGDC), polyoxyethylene tert-octyl phenyl ether (Triton X-100) and their aqueous binary combinations have been studied using different experimental techniques, e.g. tensiometry, conductometry and calorimetry. The experimental results have yielded critical micelle concentration (CMC) and counter-ion binding values. The CMC's of the mixed aggregates are observed to be lower than those of the ideal values after Clint's equation. A titration calorimeter is used to obtain the thermodynamic properties of the process of micelle formation. Entropic contributions are found to be the predominant factor in micellization. Interfacial adsorption properties such as surface excess, minimum area occupied by the head group per molecule, etc. are evaluated from the analysis of Gibb's adsorption equation. The adsorption phenomenon is observed to be more favorable compared to the micelle formation in the bulk. The CMC's of the mixed micelles and the composition of the mixed aggregates in the bulk and interfacial films have been calculated on the basis of the experimental results following the approaches of Rubingh, Motomura et al. and Rosen. An idea of the synergistic behavior of the micelles as well as the surface films is obtained from the theoretical treatments.
Abstract: Micellar properties of the binary and ternary surfactant combinations of sodium dodecyl benzene sulfonate,
polyoxyethylene sorbitan monolaurate, and polyoxyethylene lauryl ether have been investigated in detail
by employing tensiometric, fluorometric, and conductometric techniques in aqueous medium. The critical
micelle concentrations, counterion binding, interfacial adsorption, energetics of micellization as well as
adsorption, micropolarity, aggregation number, composition of the micellar species,andmolecular interaction
parameters in the mixed micelles have been evaluated. The physicochemical properties of the systems are
observed to depend on the solution composition. We have estimated the characteristics of the micellar
aggregates such as composition, activity coefficients, critical micelle concentration, and synergism of the
binary and ternary surfactant systems following the treatments of Clint, Rubingh, Motomura, et al. and
Rubingh and Holland.
Abstract: Hydrogel-coated refractive nanoparticles can self-assemble to form perfect colloidal crystalline array (CCA), which can act as a photonic sensor in visible and near-infrared region triggered by temperature. The aim of this study was to tune the lattice parameters of these CCAs made of poly-(N-isopropylacrylamide) coated silica nanoparticles and hence their sensor properties by varying various factors. The synthetic scheme of this work involves surface modification of silica nanoparticles followed by radical polymerization to obtain polymeric nanocomposites. Photon correlation spectroscopy (PCS) was used to measure the particle size of these nanocomposites with temperature variation and a sharp decrease from 1094.8 nm to 506.8 nm at the LCST (lower critical solution temperature) region was observed, which can be attributed to volume-phase transition. Atomic Force Microscopy (AFM) images complemented these results. Reflectance measurements were performed to obtain the position of photonic stop-bands as a function of temperature as well as core particle size, which can be explained with the help of Bragg's diffraction equation. With temperature increase the stop band shifted towards lower wavelength due to hydrogel collapse at elevated temperature, whereas the core particle size was directly proportional to the position of the stop band. In conclusion, self-assembly was proven to be a very simple and cost-effective approach for making photonic sensors made of polymeric nanocomposites and their sensor properties can be effectively tuned by varying certain factors.
Abstract: ATRP approach was employed to synthesis polymer-coated magnetite nanoparticles and was therefore characterized by various methods. The challenge was to obtain a thin shell and particles in an unagglomerated state. Several factors were found to play a key role in this study. This work has a remarkable biomedical application potential.
Abstract: Structuring oils can offer an alternative towards âbadâ fat usage. This can be achieved by enhancing the gelling capability of oils, which in turn also affects the texture, firmness and stability of food products. Our non-aqueous system comprises three components â oil, polymer and surfactant â each having its typical and specific role. While polymers form cross-linked network in gel, surfactants act as a plasticizer and oils behave like a solvent. A wide variety of non-ionic polymers, surfactants and oils were used in this study. Our best chosen polymer was Ethyl Cellulose with different viscosities. Cellulosic gels are known to contain ether-linked polymer strands laterally cross-linked by H-bonding (Physical Gel). Structure-wise the surfactants were varied by choosing different chain-length, head group, unsaturation, side-chains, concentration and hydrophilic lipophilic balance (HLB) values. The edible oils under study had various types of fatty acid content. Based on system composition, soft as well as firm gels were made. Differential Scanning Calorimetry (DSC), Rheometry and Scanning Electron Microscopy (SEM) as well as swelling, binding and Infra-Red (IR) studies were employed to characterize these gels. Clearing temperature was observed to be composition-dependent, whereas gelation temperature was oil-specific. It was interesting to note the existence of an exotherm during gel melting by DSC, which can be attributed to gel re-organization to a more close-packed structure. The nature of the surfactant side chain was found to modify these DSC exotherms. Attempts were made to correlate visco-elastic results of gels with polymer size, surfactant structure and oil composition. Cryo-SEM images offered further insight into the gel structure, particularly mesh-size. Percentage swelling and binding data complemented these results. In general, the interaction was found to be mostly dependent on structure and formulation of the components.
Abstract: Employing different experimental methods (tensiometric, conductometric, microcalorimetric, fluorimetric), the interfacial and bulk properties such as critical micelle concentration (CMC), counterion binding, surface excess and minimum area occupied by the head group per molecule, thermodynamics of micellization and adsorption, micropolarity in the immediate vicinity of micellar species and aggregation number (by fluorescence probing technique) were investigated. Composition of mixed entities and intermicellar interaction was also estimated from theoretical stand point.
Abstract: âNanotechnology for Water Purification' is the newest addition to academic books in the area of nanotechnology. This book explores how different kind of nanomaterials and nanostructures can be used for water treatment. Each chapter carries in-depth research-based knowledge and review of state-of-art progress.
