Cochin University of Science and Technology

About: Cochin University of Science and Technology is a education organization based out in Kochi, Kerala, India. It is known for research contribution in the topics: Thin film & Natural rubber. The organization has 5382 authors who have published 7690 publications receiving 103827 citations. The organization is also known as: CUSAT & Cochin University.

Hydrothermal Synthesis and Characterization of Undoped and Eu-Doped ZnGa2O4 Nanoparticles

Abstract: Nanoparticles of ZnGa2O4 and Eu-doped ZnGa2O4 were hydrothermally synthesized varying the process parameters, such as the volume ratio of the cation precursor solutions, temperature and time of growth, and dopant concentration. The nanoparticles were structurally characterized by X-ray diffraction, high-resolution transmission electron microscopy, and selected-area electron diffraction. The studies confirmed the formation of spherically shaped ZnGa2O4 nanoparticles with the standard spinel structure. Photoluminescence (PL) studies show that Eu-doped ZnGa2O4 nanoparticles exhibits a sharp red luminescence due to the intra-4f transitions of Eu3+ ions at an excitation of 397 nm. Luminescence quenching is observed in the nanoparticles at higher Eu concentration. The room-temperature PL measurements of pure ZnGa2O4 nanocrystals monitored at an excitation wavelength of 254 nm gave a peak-shaped spectrum instead of the normally observed bell-shaped spectrum of bulk ZnGa2O4. The bandgap of the ZnGa2O4 nanoparticles is blueshifted compared to the bulk material due to quantum confinement effects. Incorporation of Eu in the nanoparticles was confirmed by inductively coupled plasma atomic emission spectroscopic studies. (c) 2009 The Electrochemical Society. [DOI: 10.1149/1.3070662] All rights reserved.

Penaeus monodon larvae can be protected from Vibrio harveyi infection by pre-emptive treatment of a rearing system with antagonistic or non-antagonistic bacterial probiotics

Abstract: This study shows that the disease resistance and survival rate of Penaeus monodon in a larval rearing systems can be enhanced by supplementing with antagonistic or non-antagonistic probiotics. The antagonistic mode of action of Pseudomonas MCCB 102 and MCCB 103 against vibrios was demonstrated in larval mesocosm with cultures having sufficient concentration of antagonistic compounds in their culture supernatant. Investigations on the antagonistic properties of Bacillus MCCB 101, Pseudomonas MCCB 102 and MCCB 103 and Arthrobacter MCCB 104 against Vibrio harveyi MCCB 111 under in vitro conditions revealed that Pseudomonas MCCB 102 and MCCB 103 were inhibitory to the pathogen. These inhibitory properties were further confirmed in the larval rearing systems of P. monodon. All these four probionts significantly improved larval survival in long-term treatments as well as when challenged with a pathogenic strain of V. harveyi MCCB 111. We could demonstrate that Pseudomonas MCCB 102 and MCCB 103 accorded disease resistance and a higher survival rate in P. monodon larval rearing systems through active antagonism of vibrios, whereas Bacillus MCCB 101 and Arthrobacter MCCB 104 functioned as probiotics through immunostimulatory and digestive enzyme-supporting modes of action.

Microwave/Persulphate assisted ZnO mediated photocatalysis (MW/PS/UV/ZnO) as an efficient advanced oxidation process for the removal of RhB dye pollutant from water

Abstract: Microwave (MW), ultraviolet (UV) light and MW-UV combination are tested as sources of activation for the ZnO-mediated, persulphate (PS)-assisted (MW/PS/UV/ZnO) degradation/mineralization of the pollutant dye Rhodamine B (RhB) in water. The simultaneous irradiation by MW and UV is more efficient and synergistic for the mineralization of the dye compared to the respective individual energy sources. The degradation is influenced by catalyst dosage, concentration of the dye, pH of the medium, presence of contaminant salts, dissolved oxygen etc. The synergy of the MW/PS/UV/ZnO process in comparison to the respective individual processes (MW/PS and UV/ZnO) is attributed to the ‘nonthermal’ and ‘specific’ effect of MW which induce increased formation of reactive oxygen species (ROS) such as O2-, and OH radicals. Formation of surface defects which inhibits the recombination of photoinduced electrons and holes in ZnO is another major reason for the synergy. MW enhances the degradation/mineralisation of RhB even in systems with less dissolved oxygen because of the efficient transference of oxygen from the bulk of the catalyst to the surface. Another interesting observation is that simultaneous MW + UV irradiation of ZnO suspensions deaerated with N2 results in N-doped ZnO, with extended absorption in the visible range of sunlight. The potential of this simple convenient method without any cumbersome procedure for preparing N-doped ZnO needs further in-depth investigation. The study demonstrated the potential use of the combination process ‘microwave-photocatalysis’ for the efficient decontamination of water from dye pollutants.