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Search results 181 - 190 of 1458 matching essays
- 181: How Batteries Work
- ... which can be recharged by reversing the chemical reaction, was invented in 1859 by the French physicist Gaston Plante. This invention was very crucial because it would revolutionize cars. Instead of crank starts the lead-acid battery was used. The lead-acid, which Plante invented is still the same basic design today. The battery consists of six cells connected in a series, and is used in automobiles. Its chief advantage is that it can deliver a strong ... of grids containing pockets. The positive plates pockets are filled with a paste of lead dioxide (PbO2). The negative plates are filled with spongy lead (Pb). Both plates are immersed in a solution of sulfuric acid, this acts as the electrolyte. When the battery is in use, the lead atoms in the negative plates lose electrons and become lead ions (Pb++). These ions combine with the electrolyte to form a ...
- 182: The Grasslands
- ... of most continents. The worlds grasslands are vast areas covered with grass and leafy plants. They generally have a dry climate, little vegetation, and most grasslands receive only about twenty to thirty inches of rain each year, with most of it coming in the same season. Some grasslands may even receive up to thirty to forty inches of rain a year! For example, since the grasslands of the United States have hot summers and mild winters, most of the rain comes from the summer thunderstorms. With this limited amount of rain, only grasses and shrubs can grow. But some grassland areas have enough rain to support some trees such as cottonwood. With this kind ...
- 183: Mutations
- ... accidents in the replication of genetic material) or induced by external factors (e.g., electromagnetic radiation and certain chemicals). Mutations take place in the genes, which are found in the long, chainlike molecules of deoxyribonucleic acid (DNA). The backbone of the DNA chain is composed of alternating sugar and phosphate groups. Protruding from each sugar group is one of four nitrogenous bases: adenine (A), guanine (G), thymine (T), or cytosine (C ... of the bases determines the genetic code of an organism. This code directs the synthesis of proteins at the cellular level. It is written in units called codons, each of which specifies a particular amino acid. (Proteins are composed of amino acids.) A codon consists of a sequence of three bases--for example, GAG or TCA. The four bases can be assembled into 64 possible codons. Because proteins are built from ... and in most cases the effect is minimal. One reason is the redundancy of the genetic code mentioned above. Because many codons mean the same thing, the altered codon might still specify the same amino acid. Furthermore, even if a mutation causes a wrong amino acid to be inserted into a protein, the change might be harmless. Most proteins consist of scores of amino acids; a change in one of ...
- 184: How Weather Affects The Qualit
- ... this causes cars to go very slowly which in turn causes traffic jams. Some people do drive fast though and a lot of these people get into car accidents. Sometimes, but rarely, there is freezing rain, this causes ice to from on the roads making driving almost impossible. During these snowstorms or freezing rain storms the roads are so poor that school buses cannot travel or sometimes even start in the morning, because of the cold. Because of this school children cannot attend classes and miss school, much to ... bright and green and the grass is starting to grow. The kids have plenty of time to play in the beautiful weather, and have a grand time. It sometimes rains during the Spring, but the rain is soft, gentle and swift. It passes quickly refreshing and cleaning everything, leaving it smelling beautifully. During the fall on the other hand all the flowers have bloomed long ago and have lost their ...
- 185: The Life of Ernest Hemingway
- ... pleasure, and maybe he wanted to think that he was like Henry who was a nicer person. In the book, Twentieth Century Interpretations of A Farewell to Arms, Malcolm Cowley focuses on the symbolism of rain. He sees rain, a frequent occurrence in the book, as symbolizing disaster. He points out that, at the beginning of A Farewell to Arms, Henry talks about how "things went very badly" and how this is connected to "At the start of the winter came permanent rain". Later on in the book we see Miss Barkley afraid of rain. She says, "Sometimes I see me dead in it", referring to the rain. It is raining the entire time Miss Barkley is ...
- 186: Ernest Hemmingway
- ... pleasure, and maybe he wanted to think that he was like Henry who was a nicer person. In the book, Twentieth Century Interpretations of A Farewell to Arms, Malcolm Cowley focuses on the symbolism of rain. He sees rain, a frequent occurrence in the book, as symbolizing disaster. He points out that, at the beginning of A Farewell to Arms, Henry talks about how "things went very badly" and how this is connected to "At the start of the winter came permanent rain". Later on in the book we see Miss Barkley afraid of rain. She says, "Sometimes I see me dead in it", referring to the rain. It is raining the entire time Miss Barkley is ...
- 187: Living Theater
- ... drugs which helped encourage the police to chase the Living Theater out of New York. While traveling around Europe they continued to interact with artists that supported their thoughts and ways, and provided them with acid and cannabis (Acid Dreams 1). The thirty or so members of the Living Theater often tripped on acid together and sometimes performed while tripping. Beck put it this way, We were willing to experiment with anything that would set out minds free. We were practicing anarchists, and we were talking about freedom ...
- 188: Dangers and Destructions of Floods and Hurricanes
- ... 1970 a major storm in the Bay of Bengal produced heavy seas that flooded regions of East Pakistan, killing about 200,000 people.3 River flooding can happen a number of ways. The causes are rain, snowmelt, and ice jams. Soil can not absorb as much water with continuos moistening. The longer that precipitation lasts the more water flows into streams as runoff. Cloudburst floods only last for a couple hours ... large amount of rainfall. This usually only happens in mountainous areas. They are called flash floods. Floods occurring from snowmelt and ice jams do not have to be preceded by heavy rains. Moderate amounts of rain can make things even worse because the ground does not absorb it. Floods can result in the failure dams, aqueducts, weirs, landfills, paving, construction, and storm sewers. They are artificial causes. In 1993 when rainfall ... Dakota, Nebraska, and Kansas, it covered about 16 billion acres.4 Many deaths and $10 billion in damage was the result flood level records.5 In March of 1936 snowmelt equaling 10-30 in. of rain occurred in New England.6107 people died and $270 million in damage was done.7 In 1972 at Logan County, West Va. a dam collapsed following three days of rain. In less than four ...
- 189: Discovering Sicke Cell Anemia
- ... from a disc shape to a sickled shape. In hemoglobin, there are four chains of amino acids. Two are know as alpha chains, and two are called beta chains. In a normal hemoglobin, the amino acid in the sixth position on the beta chain is known as glutamic acid (refer to diagram 1.1 on page 6). During sickle cell anemia, the glutamic acid is pushed out of its place and replaced with another amino acid called vialine(refer to diagram 1.2 on page 6). This simple substitution has devastating consequences. Hemoglobin molecules that contain the beta ...
- 190: Prolonged Preservation of the Heart Prior to Transplantation
- ... that lacked pyruvate had a significantly lower rate of contractile function once they were transplanted. The superior preservation of the hearts with pyruvate most likely resulted from the hearts use of pyruvate through the citric acid cycle for the production of energy through direct ATP synthesis (from the reaction of succinyl-CoA to succinate via the enzyme succinyl CoA synthetase) as well as through the production of NADH + H+ for use ... to produce energy. After providing a preservation media that contained pyruvate, a better recovery of the heart tissue occurred. Most of the pyruvate consumed during preservation was probably oxidized by the myocardium in the citric acid cycle. Only a small amount of excess lactate was detected by the assays of the preservation media discharged by the heart. The lactate represented only 15% of the pyruvate consumed. If the major metabolic route taken by pyruvate during preservation had been to form lactate dehydrogenase for regeneration of NAD+ for continued anaerobic glycolysis, rather than by the aerobic citric acid cycle (pyruvate oxidation), then a higher ratio of excess lactate produced to pyruvate consumed would have been observed. Hearts given a glucose substrate did not transport or consume that substrate, even when it was ...
Search results 181 - 190 of 1458 matching essays
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