Defects and Calcium Diffusion in Wollastonite

Wollastonite (CaSiO3) is an important mineral that is widely used in ceramics and polymer industries. Defect energetics, diffusion of Ca ions and a solution of dopants are studied using atomistic-scale simulation based on the classical pair potentials. The energetically favourable defect process is calculated to be the Ca-Si anti-site defect cluster in which both Ca and Si swap their atomic positions simultaneously. It is calculated that the Ca ion migrates in the ab plane with an activation energy of 1.59 eV, inferring its slow diffusion. Favourable isovalent dopants on the Ca and Si sites are Sr2+ and Ge4+, respectively. Subvalent doping by Al on the Si site is a favourable process to incorporate additional Ca in the form of interstitials in CaSiO3. This engineering strategy would increase the capacity of this material.

Approximation of Calcium Diffusion in Alzheimeric Cell

Alzheimer’s disease (AD) is the most common form of dementia prevailing worldwide. It has been found that the higher level of cytosolic calcium leads to the pathological symptoms of AD and the two cytoplasmic calcium binding buffers have their roles in sustaining this dementia. However, the area of their functioning and working is found to be different. Calmodulin is found in CA1-hippocampus neurons, whereas calbindin-D28k is found in basal forebrain cholinergic neurons. Based on this physiology, in this research paper an attempt has been made to delineate the physiological phenomenon of calcium diffusion at cytosolic level. Taking into consideration the physiology of the neuron, a two-dimensional mathematical model is used and is solved using finite element method (FEM). The appropriate initial and boundary conditions are assumed in presence of suitable diffusion coefficient of calcium and association rate of the buffer. The approximate geometries for both the neurons are taken into consideration to get a better insight about the pathology behind calcium diffusion taking place in AD. The desired results are shown graphically for Alzheimeric and non-Alzheimeric cells. Thus, the obtained results clearly show the significant impact of buffers on cytosolic calcium which affect the normal condition of the cell and maintain the cell calcium.