Balaji Subramanian

Characterization of Shrimp Oil from Pandalus borealis by High Performance Liquid Chromatography and High Resolution Mass Spectrometry

Northern shrimp (Pandalus borealis) oil, which is rich in omega-3 fatty acids, was recovered from the cooking water of shrimp processing facilities. The oil contains significant amounts of omega-3 fatty acids in triglyceride form, along with substantial long-chain monounsaturated fatty acids (MUFAs). It also features natural isomeric forms of astaxanthin, a nutritional carotenoid, which gives the oil a brilliant red color. As part of our efforts in developing value added products from waste streams of the seafood processing industry, we present in this paper a comprehensive characterization of the triacylglycerols (TAGs) and astaxanthin esters that predominate in the shrimp oil by using HPLC-HRMS and MS/MS, as well as 13C-NMR. This approach, in combination with FAME analysis, offers direct characterization of fatty acid molecules in their intact forms, including the distribution of regioisomers in TAGs. The information is important for the standardization and quality control, as well as for differentiation of composition features of shrimp oil, which could be sold as an ingredient in health supplements and functional foods.

Crack-free 2D-inverse opal anatase TiO2 films on rigid and flexible transparent conducting substrates: low temperature large area fabrication and electrochromic properties

Two-dimensional (2D) inverse opal (IO) TiO2 films, synthesized by colloidal crystal templating, such as polystyrene (PS) spheres, are particularly interesting because of their potential applications in sensors, solar cells, and electrochromic devices. For these applications, high crystallinity is essential for device performance. Usually, to achieve the IO structure with high crystallinity, the PS opal template is first removed by calcination at a temperature of ∼400 °C, and subsequently to crystallize amorphous TiO2, a temperature higher than 400 °C is needed. This results in cracks and collapse of the macroporous framework. Furthermore, this route is limited to thermally stable substrates, such as glass, which is a significant drawback as the increasing development of technologies and modern electronics requires the design of inexpensive, lightweight, and efficient optoelectronic devices on flexible substrates. In order to circumvent these problems, we developed a ‘dynamic-hard-template’ infiltration strategy for the fabrication of large-area crack-free nanocrystalline (NC) anatase 2D-TiO2 IO films on rigid transparent conducting substrates and on ITO coated flexible polyethyleneterephthalate (ITO/PET) substrates, by using various sizes of PS spheres. According to this strategy, first a dynamic opal 2D film of PS spheres is self-assembled on the surface of water, followed by the infiltration of preformed anatase TiO2 nanoparticle sol from the bottom into the PS opal crystal as the guest material, thus eliminating the need for high temperature crystallization. The obtained floating PS/TiO2 opal composite film is deposited on ITO-coated glass and ITO/PET substrates. An optimized low temperature chemical method is adopted to remove the PS template to yield NC anatase 2D-TiO2 IO films. The films obtained on ITO/PET substrates were successfully used as an active electrode in the fabrication of a flexible electrochromic device.

Implication of Porous TiO2 Nanoparticles in PEDOT:PSS Photovoltaic Devices

Recent developments in the synthesis of mesoporous nanocrystalline titanium oxide (TiO2) have opened up several new opportunities in the construction of efficient photovoltaic (PV) cells. In this chapter, we describe principles involved in the construction of organic photovoltaic cell and the influence of the main parameters for the case of PEDOT:PSS polymers. At the outset different architectures of the PEDOT:PSS photovoltaics are described and later incorporation of the TiO2 nanoparticles in their architectures is carefully considered. A special attention is given to the technique of photovoltaic cell preparation and the basic principles of their functionality. A significant emphasis has been devoted to the current–voltage characteristics of photovoltaic cells, thus constructed with and without nanocrystalline TiO2, as well as to the ways it can be further improved. We also describe the synthesis of mesoporous TiO2 nanoparticles using titanium alkoxides as precursor and polyethylene glycol (PEG) of different molecular mass as templating agent to induce mesoporosity. The interaction of PEG with titanium alkoxides in polar and nonpolar solvents was studied in detail by macro-Raman spectroscopy, solid-state NMR and MALDI-TOF-MS. The removal of PEG as well as the crystallization process was obtained by hot water treatment at low temperature (90 °C). The mesoporosity was retained after further calcination up to 500 °C. Porosity, morphology, and microstructures of the resultant products were characterized by SEM, nitrogen adsorption–desorption measurements, micro-Raman spectroscopy and XRD. The mesostructure of the TiO2 particles facilitates enhanced transport of electrons, resulting in improved photovoltaic efficiency. Influence of TiO2 nanoparticles on the photovoltaic efficiency of the ITO/PEDOT:PSS/fluorine copolymers/polythiophene:TiO2/Al architecture is analyzed. Influence of TiO2 NP on the principal parameters of different PV architecture is discussed. The analysis of the efficiency is performed using both experimental and theoretical quantum chemical approach.