Study on Strength and Self-Healing Behaviour of Bio-Concrete

Micro cracks are very commonly observed in concrete structures. Due to increased permeability through these micro cracks, durability of concrete structures reduces by the entry of chemical through these micro pores particularly in moist environments. In the field, crack repair is labour intensive. It is more advisable to restrict the early age small cracks the moment they appear instead of repairing after large cracks formed. In order to increase the durability of concrete against these commonly observed pores in concrete structures, autogenous pore refinement method can be adopted so that monitoring of the structure against these micro pores can be avoided. By using the principle of Biomineralization, Bacteria forms the Calcium precipitations which is usually called microbial induced calcite precipitation (MIC) .In the present work, the bacteria which will grow in the high alkaline media is chosen since concrete is highly alkaline material and cultured in the controlled medium to get the desired concentration of cells. In the present work, Un-identified and Bacillus sphericus bacterial broth is used for the study. It is observed that these bacteria when mixed with concrete at the concentration of 106 cells per ml, the compressive strength is increased by 36.36 % and 13.63 % and for 107 concentrations of cells, the un-identified bacteria show the increase of compressive strength as 29.56 %. Modulus of elasticity of concrete is increased by 23.78 % and 31 % for both bacteria at the concentration of 106 cells per ml of water and Split tensile strength is increased by 23.5 % and 28.5 % for concentration 106 and 107 cells of Bacillus sphericus. SEM and EDAX analysis reveals the deposition of calcium carbonate Keywords: Self-healing, bio mineralization, strengt

Low Temperature Dielectric and Impedance Studies on Magnetoelectric Pb(Fe0.5Nb0.5) O3 Ceramic

The structural, microstructural, low temperature dielectric and impedance properties of Pb(Fe0.5Nb0.5)O3 (PFN) ceramic prepared by single step solid-state reaction method have been investigated. Processing parameters such as calcination, sintering temperature and sintering durations were optimized to get better dielectric properties. It was found that the above ceramics sintered at 1050 °C for 4 hr exhibited single phase, maximum density and uniform microstructure. X-ray diffraction (XRD) and neutron diffraction (ND) reveals that the system exhibit single phase without any kind of secondary phases at room temperature (RT) with monoclinic crystal structure (Cm). Surface morphology of the compounds was studied by Scanning electron microscope (SEM). Impedance spectroscopy is used to study the electrical behaviour of PFN in the frequency range from 100Hz to 1MHz and in the temperature range from 120 to 293 K. The frequency-dependent electrical data are analyzed by impedance formalisms. The complex impedance shows the relaxation (conduction) mechanism in the sample

Delayed Onset of Mixed Cranial Neuropathies and Cluster Headache After Embolization of Indirect Carotid-Cavernous Fistula

Carotid cavernous fistulas (CCF) often present with diplopia secondary to cranial nerve palsy (CNP). Immediate development of postoperative CNP has been described in the literature. This study described delayed- onset of CNP after complete and reconfirmed obliteration of the CCF and resolution of initial CN