Materials Science Forum Vol. 760

Abstract: Ti_0.985Co_0.015O_2-δ thin films are deposited at 0, 0.1, 1 and 300 mTorr oxygen partial pressures by pulsed laser deposition (PLD) technique. Glancing angle x- ray diffraction (GAXRD) and micro-Raman spectroscopy show that the phase changes from rutile to anatase with increasing oxygen partial pressure. From Rutherford backscattering spectroscopic (RBS) technique, O to (Ti+Co) atomic ratio is found to increase with increasing oxygen partial pressure. Further, the simulation of RBS data while reveals non-uniform distribution of Co throughout the film deposited at 0 and 0.1 mTorr oxygen partial pressures, at 1 and 300 mTorr oxygen partial pressure, Co distribution is found to be uniform. Magnetic measurements confirm the room temperature ferromagnetism (RTFM) in all the films independent of the phase. Magnetic force microscopy (MFM) further supports the ferromagnetic nature of the films. We attribute the ferromagnetism in the films to be arisen from defects like oxygen vacancies rather than any contamination or Co clustering.

Abstract: The proposed study was to synthesize silver nanoparticles by using filamentous fungus Penicillium fellutanum. From the ancient period, silver has been used against microorganisms due to its own antibacterial properties. The fungal culture of Penicillium fellutanum was isolated from the soil samples of Sathyabama University, Chennai, Tamil Nadu, India. The fungal isolates were inoculated in culture medium and incubated at room temperature for three days and the culture filtrate was separated and divided into two parts. One part of the culture filtrate was mixed with equal volume of 1mM silver nitrate [AgNO_3,(1 mM)] and agitated at room temperature in dark condition. And the second half was kept as such. In the other hand only 1mM silver nitrate was added into the equal volume of Milli Q water and one half was plain Milli Q water. All the four samples were tested against pathogens like Bacillus cereus, E. coli, Proteus vulgaris, Staphylococcus aureus, Staphylococcus epidermidis and the results were compared. Proteus vulgaris showed the highest zone where E coli showed the least zone of inhibition, in the culture filtrate added with silver nitrate. The cell filtrate on treatment with silver nitrate and prior incubation were observed for change in color and characterized by UV-Vis spectrophotometer which detected AgNPs in the solution. The maximum absorbance 410nm confirmed the formation of silver nanoparticles. Size and morphology of silver nanoparticle were investigated using Atomic Force microscopy (AFM). The silver Nanoparticles after confirmation were checked for its antibacterial activity against selected pathogenic bacteria. The biologically synthesized Nanoparticles from Penicillium fellutanum showed the good inhibitory effect against the selected pathogens, which would be the novel remedy substituent in the place of high dose antibiotics.

Abstract: An efficient and simple synthesis of 17-chalconyl derivatives of pregnenolone and their antibacterial and antifungal evaluation is reported. The scheme involves the transformation of the starting pregnenolone to the corresponding Chalcone derivatives by the well-known Claisen-Schmidt reaction. Determination of Minimum inhibitory concentrations (MICs) is reported on these newly synthesized Chalcone derivatives of pregnenolone. The prediction of molecular properties is also discussed. Compounds showing lower MIC values also followed Lipinski’s rule of 5. The results showed that the activity of the tested agents against each microbe varies due to structural differences between the microorganisms.

Abstract: Thermogravimetric experiments on prereduction of single pellet and multiple pellets were conducted in Muffle furnace at 1500oC. Reduction smelting of Chromite in Fe-C melt in TG setup indicates CR is reduced faster than CG and CB. The reduction mechanism takes the path of first order reaction kinetics. Only 50% Cr metallization could be obtained at 1550oC from the reduction smelting experiments.

Abstract: Silver Nanoparticles (Ag-NPs) have been known to have inhibitory and bactericidal effects. Resistance to antimicrobial agents by pathogenic bacteria has emerged in recent years and is a major health problem. The ability of some microorganisms such as bacteria and fungi to control the synthesis of metallic Nanoparticles should be employed in the search for new materials. The present work is the study of biosynthesis of silver Nanoparticles synthesized from different Penicillium spp. The Penicillium species were identified by employing microscopic methods and laboratory manuals. The Nanoparticles synthesis was done by extracellular and intracellular methods. The silver Nanoparticles formed were characterized by Uv-vis spectrophotometer followed by TEM analysis. The maximum absorbance 410nm confirmed the formation of silver Nanoparticles and TEM revealed the particle size in the range of 30-40nm, which after confirmation was checked for its antibacterial activity against selected microbial pathogens like Bacillus cereus, Proteus vulgaris, Staphylococcus aureus and Staphylococcus epidermidis. The Nanoparticles synthesized by Penicillium species showed a well anti microbial activity that was further compared with different antibiotics to check the Nanoparticles activity which can be substituted in place of high dose antibiotics.

Abstract: Hydroxyapatite is a bioceramic which has a wide range of medical application for bone diseases. To enhance its usage, we have prepared ciprofloxacin loaded nanohydroxyapatite (HA) composite with a natural polymer, alginate, using wet chemical method at low temperature. The prepared composites were analyzed by various physicochemical methods. The results show that the nanoHA crystallites are well intact with the alginate macromolecules. For the composite system FT-IR study is done. The drug is pre-adsorbed onto the ceramic particle before the formation of composite. The thermal behavior of composite has been studied using thermo gravimetric analysis (TGA). This paper communicated the Influence of Polymer concentration on the Controlled drug release from hydroxyapatite Nanocomposites

Abstract: Microscopy is the characterization of objects smaller than what can be seen with the naked human eye, and from its inception, optical microscopy has played a seminal role in the development of science. In the 1660s, Robert Hooke first resolved cork cells and thereby discovered the cellular nature of life. Robert Browns 1827 observation of the seemingly random movement of pollen grains [ led to the understanding of the motion that still bears his name, and ultimately to the formulation of statistical mechanics. The contributions of optical microscopy continue into the present, even as the systems of interest approach nanometer size. What makes optical microscopy so useful is the relatively low energy of visible light: in general, it does not irreversibly alter the electronic or atomic structure of the matter with which it interacts, allowing observation of natural processes in situ. Moreover, light is cheap, abundant, and can be manipulated with common and relatively inexpensive laboratory hardware.Science and technology ever seek to build structures of progressively smaller size. This effort at miniaturization has finally reached the point where structures and materials can be built through atom-by-atom engineering. Typical chemical bonds separate atoms by a fraction of a nanometer (109 m), and the term nanotechnology has been coined for this emerging area of development. By manipulating the arrangements and bonding of atoms, materials can be designed with a far vaster range of physical, chemical and biological properties than has been previously conceived. But how to characterize the relationship between starting composition, which can be controlled, with the resulting structure and properties of a nanoscale-designed material that has superior and unique performance Microscopy is essential to the development of nanotechnology, serving as its eyes and hands.

Abstract: Prevalence of airborne fungal spores with their seasonal periodicity in the extra and intramural environments of a saw mill of Pondicherry region was carried out by gravitation method from January 2011 to December 2011. Composition and concentration of fungal spores considerably varied from indoors to outdoors as well as from season to season. Indoor air harbored maximum fungal spores (61%) in comparison to outdoor air (39%). Occurrence of fungal species was predominated with more number of propagules during mid winter (December) and early rainy (July) periods in comparison to other months. Quantitatively, Cladosporium was found with the highest frequency and had four members i.e., C. cladosporioides, C. herbarum, C. resinae, C. sphaerospermum but qualitatively, Penicilli and aspegilii were isolated highest in its contribution to total CFUs. Out of the 32 isolated fungal taxa, Aspergillus fumigatus, A. niger, Rhizopus stolonifer and Alternaria alternata were the predominant aeroallergens which cause different types of respiratory/lung diseases in atopic human beings were isolated. In seasonal periodicity, winter contributed the maximum spore load (41%) followed by rainy (33%), summer was found with the least (26%) in harboring the spore mass in the indoors and outdoors. Alternaria alternata, which is accounted as a human allergen for sporosis inducer and an agent for hay fever and other pathologies, was also intermittently recorded. A few plant pathogenic fungi like Helmithosporium sp. & Fusarium spp, saprophytic, field and storage fungi were also recorded during the study period. Effect of meteorological parameters on the fungal spores in the saw mill atmosphere was significantly assessed by Pearsons correlation coefficient analysis.

Abstract: An aero-allergenic fungus in the indoor environments has been associated with adverse respiratory symptoms leads to different allergenic diseases viz., allergic asthma, bronchitis, rhinitis, and hay fever in the atopic human beings. Moreover, fungal assessment and exposure has traditionally relied upon questionnaires for health issues especially to children. The present study is an attempt to record the incidence and seasonal periodicity of airborne fungal spores in indoors and outdoors of an industrial city house, Hosur, Tamilnadu by Petri-plate settlement method. In qualitative and quantitative way, fungal spores considerably varied from indoors to outdoors as well as from season to season. Apart from fungal growth on culture plates and spore counts, new immunoassays for extracellular polysaccharides (EPS) have enabled quantisation of fungal agents in house dust in a more timely and cost-effective manner, possibly providing a better measure of fungal exposure. The present data investigated outdoor air harbored maximum fungal spores (53%) in comparison to indoor air (47%). Incidence of fungal species was predominated with more number of propagules during mid winter (December) and early rainy (July) periods in comparison to other months. Qualitatively, Aspergillus was found with the highest frequency and had eleven members i.e., A. awamori, A. fumigatus, A. niger, A. flavus, A. flavipes, A. nidulans, A. ochraceous, A. japonicus, A. terreus, A. versicolor and A. wentii, but quantitatively, Penicillium was isolated highest in its contribution to total CFUs followed by Aspergillus. Out of the 32 isolated fungal taxa, Aspergillus fumigatus, A. awamori, A. niger, Rhizopus stolonifer and Alternaria alternata were the predominant aeroallergens, which cause different types of respiratory/lung diseases among atopic human beings. Samples were sieved and fine dust was analyzed for EPS from Aspergillus and Penicillium spp., though they are considered as more allergenic. In seasonal periodicity, winter contributed the maximum spore load followed by rainy. Summer was found with the least in harboring the spore mass in the indoors and outdoors. Alternaria alternata, which is accounted as a human allergen for sporosis inducer and an agent for hay fever and other pathologies, was also intermittently recorded. The extracellular polysaccharide (EPS) collected was further treated against the human pathogen to check its antimicrobial activity, which can be used as a good replacement of antibiotics.