Alzheimer's Disease Research Paper Example | Topics and Well Written Essays - 2000 words

Alzheimer's Disease - Research Paper Example Alzheimer is mostly seen in individuals who are above the age of forty five and it principally develops into dementia in its latter stages. It is characterized by loss of cognitive abilities which occurs due to the loss of normal brain functions. In the latter stages of Alzheimer Disease the sufferer becomes totally disoriented and shows memory loss such that he is not able to recognize his very close family members. (Evans et al, 1989; Gao et al, 1999). The primary feature of Alzheimer Disease is the atrophy of the cortex. But in some cases it is seen that neuritic processes may accumulate, abnormalities in cerebral nucleus may occur or amyloid angiopathy may be seen. It is seen that Alzhemier Disease does not show any symptoms early at age but after a person reaches 50 the symptoms become obvious. As an individual ages the chances of the disease increase even more often reaching to a level of 40% in individuals who are in their eighties ((Evans et al, 1989; Gao et al, 1999; Strauss et al 1999 ). Studies on the disease have shown that cortical atrophy is the major cause of the disease. The cerebral sulci become more prominent in the temporal, frontal and parietal lobes. To cover up for this atrophy usually the ventricle in the brain enlarges. Microscopic studies have shown that neuritic plaques and neurofibrillary tangles accumulate along with amyloid angiopathy. Neuritic plaques are spherical neuritic processes which surround the central amyloid core in Alzheimer. Neurofibrillary tangles are a group of filaments which are found in the cytoplasm of the neurons that usually surround the nucleus. Amyloid angiopathy is a sign of Alzhemier Disease bu t it can also be found in other diseases. It is believed that Alzheimer later progresses to dementia in individuals because of loss of choline accetyltransferase, synaptophysin immunoreactivity and loss of synaptic transmission. It is believed that Alzheimer is primarily caused by a protein known as AÃŽ ². AÃŽ ² is

Technical definition and description Essay Example | Topics and Well Written Essays - 750 words

Technical definition and description - Essay Example According to a brief definition suggested by Chen, Hassan, and Yu; â€Å"a fuel cell is an electrochemical cell that converts chemical energy from a fuel into electrical energy† (58). A fuel cell generates electricity through chemical reactions between a fuel and an oxidant in the presence of an electrolyte. A notable feature of the fuel cell is that it can operate continuously as long as proper reactant and oxidant flows are maintained. Fuel cells generate nonpolluting power, and they perform outstandingly in terms of efficiency. Since fuel cell have no moving parts, they product little noise. Fuel cells have been serving the energy needs of spacecrafts since 1960s on the strength of its ability to operate uninterruptedly. In spite of the recent advancements in the technology, fuel cells are still increasingly used in power generating plants and exhaust-free automobiles. The major difference between a batter and a fuel cell is that the former has a fixed supply of energy whereas the latter can generate energy continuously as long as the fuel is supplied. Like a battery, a fuel cell is made up of a large number of individual cells that are collectively called a fuel cell stack. All these individual cells are comprised of an anode, a cathode, and an electrolyte. In a fuel cell, anode is generally made of platinum because it can better catalyze the reaction ionizing the gas. When a hydrogen-rich fuel like renewable biogas or clean natural gas is supplied to the fuel cell stack, ‘it reacts with oxygen electrochemically to produce electric power, heat, and water’ (How do fuel cells work). Although different types of fuel cells operate a bit differently, basically they all work based on the same process. In a fuel cell, hydrogen atoms enter the anode where their electrons are stripped off through a chemical reaction. Thus, the hydrogen atoms become ionized, and resultantly they carry a positive charge. At the same time, the negatively