Examine the tensile strength of three specimen of low, medium and high carbon steels is examined

The aim of this laboratory experiment is to examine the tensile strength of three specimen of low, medium and high carbon steels is examined. The microstructure of the specimen is determined and calculations such as tensile strength, yield strength etc were clearly recorded. Also, the background theory was stated, the apparatus and procedure used to achieve the experiment was described. The main part of this lab report is the discussion on the results and how close they've been calculated to the original theoretical values by taking into consideration some external experimental errors. The last part of this report is the conclusion on the whole procedure. INTRODUCTION The main purpose of this lab report is by using a tensile testing machine (Hounsfield tensometer), to determine mechanical properties of three different plain carbon steel materials (low carbon steel, medium carbon steel and high carbon steel). Also, their grain structure is to be examined using a Metallurgical microscope. BACKGROUND The three different materials are the low-carbon, medium-carbon and high carbon steels. Their tensile strength is examined which by definition is explained as the amount of stress that a material can resist when a force pulls it along its length until a complete deformation takes place. A ductile material is a material that contains the properties of plasticity and tenacity and it's able to change its shape when a force acts on it and can keep that changed shape even after that force is removed. (Timings R. 2006) The tensile test is mainly used to specify the strength and ductility of a material. Also the tensile test involves: 1. Material showing a yield point which is the point that an extension takes place without any increase in load 2. Proof stress which is used to determine the amount of plastic deformation. 3. Secant modulus which is used to determine the elasticity of the material. (Timings R. 2006) Plain carbon steels: Ferrous metals are basically a metallic material (iron) and it means that iron is combined with carbon. Iron and carbon, the simplest of the ferrous metals (Latin ferrum=iron), are the main elements of plain carbon steels. Low-carbon steels have a carbon content 0,1-0,3% in addition to impurities. This kind of steels cannot be directly hardened by heat treatment, but they can be readily carburized and case hardened. The type of medium-carbon steels have a carbon content 0,3-0,5%. They can be toughened by heat treatment. All types of high carbon steels (carbon content 0,8-1,0%) are extremely strong and their response to heat treatment is better than the medium-carbon steels. However, because of the high carbon content they can be hardened to a high degree of hardness. (Timings R. 2006) The iron-carbon (Fe-C) diagram in figure1 helps to study and learn more about the microstructure of carbon steels as well as their heat treatment. Figure1. â€Å"The Fe-C phase diagram shows which phases are to be expected.† (1) â€Å"At the low-carbon end of the Fe-C phase diagram, we distinguish ferrite (alpha-iron), which can at most dissolve 0.028 wt. % C at 738 à ¯Ã‚ ¿Ã‚ ½C, and austenite (gamma-iron), which can dissolve 2.08 wt. % C at 1154 à ¯Ã‚ ¿Ã‚ ½C.† (1) EXPERIMENTAL PROCEDURE In order to complete this test, three tensile test specimens, each of different carbon content, are given. Also a tensometer machine is available in order to tense the specimens. The machine works as follows: Firstly, the specimen is placed on the machine and a force pulls it along its length. This force is measured (in kN) on a digital force meter which is connected to the machine. On the top there is a cylinder with a graph paper around it in order to sketch a graph of force against the extension of the specimen. This is done by moving the pointer on the graph paper by 0,5kN respectively and pointing on the graph each time the reading on the digital force meter increases by 0,5kN, for instance, if the reading reaches 1,0kN the pointer has to be pointing at 1,0kN and by the time that the reading is 1,0kN a point is sketched on the graph. (See figure 2 below) Figure 2. Furthermore, measurements of the length and cross-sectional area were taken before and after the test in order to determine the percentages of elongation and the reduction in area. The last part of the experiment is to examine the three micro-specimens given which is the exact same material and condition as the three materials used on the tensile machine and determine the percentage of the carbon content of their grain structure. This is done by using a Metallurgical Microscope. RESULTS The results of the experiment were calculated and recorded on a table as shown below: Test piece material % carbon content Yield strength (N/mm2) Ultimate tensile strength (N/mm2) % elongation % reduction in area Specimen A Low-carbon steel 0,1 315 430 37 66 Specimen D Medium-carbon steel 0,4 475 660 28 62 Specimen N High-carbon steel 0,8 932 960 13 30 All the specimens had normalized treatment conditions. Graphs were plotted for every specimen, which state clearly the points of force and extension. (See Tables below) The ultimate tension strength (uts) was calculated by the following formula: â€Å"† (3) The yield strength (ys) was calculated by the following formula: â€Å"† (4) The elongation percentage (elon.) was calculated by the following formulae: â€Å"† (5) The reduction in cross-sectional area (red.csa) was calculated by the following formula: â€Å"x 100† (6) Microstructure results The following specimens are the result of the experiment. The white region of each specimen is ferrite and the gray region is pearlite. The carbon content is determined using the iron-carbon (Fe-C) phase diagram. SPECIMEN A SPECIMEN D SPECIMEN N DISCUSSION The experiment is now completed and a discussion about the results is made. The values calculated in the experiment are going to meet the theoretical values of the three specimens used. In the table below all the results were recorded: CALCULATED THEORETICAL Low carbon steel UTS (N/mm2) 430 162-3200 YS (N/mm2) 315 140-2400 ELONGATION (%) 37 1-48 REDUCTION A. (%) 66 13-99 Medium carbon steel UTS (N/mm2) 660 450-2290 YS (N/mm2) 475 245-1940 ELONGATION (%) 28 0.6-34.2 REDUCTION A. (%) 62 0.2-71.4 High carbon steel UTS (N/mm2) 960 161-3200 YS (N/mm2) 932 275-2750 ELONGATION (%) 13 1.9-30 REDUCTION A. (%) 30 13.4-75.2 The table above show clearly that the calculated values are close to the theoretical values. This means that the experiment was successful and the calculation were correct. Although, there's always a small percentage error in every experiment. The most common error in every experiment is the human error and this is the main type of error that may took place in this experiment. Also, differences in temperature and the purity of the material used is an important issue. Furthermore, from the examination of determining the grain structure of each material under the microscope the difference between them was very clear. For instance, the different amount of ferrite and pearlite could be identified, high-carbon steel had darker color than low and medium carbon steels which means that the amount of pearlite is almost 100%. Also, from the tables plotted on the tensometer machine the load that every specimen could withstand, the elongation percentage and the reduction in cross-sectional area were different. By considering these values, low-carbon steels have the least amount of load before complete deformation and the most percentage on both reduction in cross-sectional and elongation of the three specimens. This means that low-carbon steels have the least amount of carbon. In addition, low carbon steels can be defined as ductile materials. Medium-carbon and high-carbon steels are less ductile have les percentage of elongation. This means that they are harder and they are applied more load in order for deformation to take place. Finally, the last part of the discussion is about the different yield point of the three specimens. If the graphs are considered, a sudden fall of the load appears to take place on the graphs of low and medium carbon steels during the procedure. This means that the two specimens faced a reduction in cross-sectional area (also known as necking). This doesn't seem to happen to the specimen of high-carbon steel which means that the deformation took place without having any noticeable reduction in cross-sectional area as the load was kept increasing. CONCLUSION In conclusion, the three specimens where tested and results were given. Since the calculated values meet the theoretical values, the experiment was successful. Discussion about the ductility and the main structure of the given specimens was made and also the differences between them were stated.

Team Role Paper

Team Role Paper Learning Team A COM100: Introduction to Communication Jan Bozwell, instructor Team Roles Working in teams can be a tricky task for a good majority of people, but being able to designate roles to each team member can help promote the teams effectiveness, cohesion and advance the project completion. Designating roles for the members of a group can increase effectiveness because it helps cater specific roles to a specific need that supports the team’s collaborative effort. Some roles that help in this effort are the leadership role, the encourager, analyst, and a secretary.Each role has a certain responsibility that can ensure success and effectiveness. The leader is one of the most important roles, the leader helps keep the group on task; he/she maintains the schedule of meetings, and deadlines. The encourager helps guide the discussion to maintain a forward momentum. The analyst is the facts checker; their main responsibility is to make sure that information is correct (Indiana University: Bloomington,  2012). The final role belongs to the secretary, this person’s responsibility is to make sure ideas are recorded and submitted on time.Each designated role plays a major part in the effectiveness of the team’s final project. Effectiveness of a group is paramount in keeping a group on track and maintaining a deadline, but cohesion can be just as important for a team. By assigning roles to individual team members, you’re building cohesion. Individuals possess a variety of strengths and weaknesses which can often complement each other in a team setting. The strengths of one team member may help balance the weaknesses of another. By splitting a project into smaller tasks based on individual strengths, team members are forced to trust and rely on one another to omplete parts of the project. When tasks overlap or are ready to come together, communication between team members helps create unity as the team works toward a comm on goal. Giving roles to members of a team also creates a sense of ownership and pride in the overall project. When individuals are invested in a project, they are naturally drawn closer to others with a similar goal. According to Stahl (2012), â€Å"Working together, each bringing our gifts and not only valuing, but seeking those of others enables us to create the best possible solutions. † (p. 6) When people see the value others are able to provide to the quality of a project, a mutual sense of accomplishment brings them together. Being able to bring team members together on a project they feel pride in, allows for the best possible work to be put forth. But, not only does taking pride help, but effective meetings and an equal share of responsibility helps keep the team on task. Assigning roles and responsibilities in a team is essential for project completion. When a team leader wants to achieve excellence with the group, the selection of tasks will be optimized if they us e all of the member’s experiences and skills.The single most important goal in team success is having effective team meetings. Team meetings create responsibilities for team members so they are up to date on the project deadline. The more communication and the more goal oriented a team is, the better the outcome of the project. Kennedy (2008) says, it is always important to maintain focus and create responsibilities for the task and team. When these responsibilities and roles are established it creates common expectations. A timeline is essential as well, as far as setting date on completing projects and checking in.Successes of projects come with being responsible, and communication within a team. Being able to designate roles can help tremendously, allowing a team to complete their assignment promptly and efficiently. Team members are more engaged when they have a clear outline of the work at hand, and what is expected of them. As well as feeling like they’re part of the finished product, no matter what their role turned out to be. By focusing on individual strengths, sharing the work load and allowing for equal input, you push team cohesion and effectiveness to its limits.References Indiana University: Bloomington. (2012). Teaching and Learning. Retrieved from http://www. teaching. iub. edu/finder/wrapper. php? inc_id=s2_5_group_03_designate. shtml Stahl, M. (2012,  June). Creating Dynamic Teams–The Power of Working Together, Stronger, Bolder!†¦ Dynamics of Critical Care 2012, Vancouver, British Columbia, September 23-25, 2012.. Dynamics, 23(2), 36. Frances Kennedy. (2008). Successful Strategies for Teams. Clemson University. Retrieved from http://www. clemson. edu/OTEI/documents/teamwork-handbook. pdf

Walmart Management Problems Essay Example | Topics and Well Written Essays - 2000 words

Walmart Management Problems - Essay Example This creates the room for misjudging competitors and harming the relationship that the retailer will have with local suppliers. This is not the only problem that Wal-Mart faces the other problems include unions, low wages, sex discrimination, and others that have tarnished the name of the store. Wal-Mart Management Problems Looking at the last two decades will show how the global economy has gone through a radical transformation. Despite the fact that there are different geographic locations around the world separated by oceans and seas, improvement in technology has made the distance shrink completely. Some of the technological innovations that have made this possible are airplanes, satellite broadcasting, computers, fax machines, internet, and others. Technology has made it possible for business to expand internationally and get different suppliers from different parts of the world. Many people will talk about globalization and it simply refers to the worldwide economic activities of free flow of services, goods, knowledge, capital, competition, and open markets. Through globalization, global companies have been able to establish themselves in local markets while local companies have been able to go global. ... This is because it already has stores in Asia, Europe, and South America. Its expansion efforts are still on, as it has plans of putting up more stores both domestically and internationally (About Wal-Mart, 2001). The fact that the store is number one in the US does not guarantee it will be number one in the other countries. This is because of the challenges that lie ahead with the regulations of the country where it will be opening its stores and the local supplier’s willingness to supply the store with products. The culture adopted in the region will tell a lot if the store will be able to achieve its objective of being in business while offering customers with quality products and services. Despite globalization being good news for businesses, it has made competition to increase with the increase in number of competitors. The fact that everyone is currently concerned with the environment and looks for all possible means in which they can conserve the environment makes envir onment friendly businesses have an upper hand in dominating the market. Customers will be attracted to companies that are out to protect our environment that is already destroyed rather than companies that are out to see complete destruction of the little beauty left in our environment. Going green will help in ensuring that you have constant market for your goods and services. The Wal-Mart Culture (2004) explains Wal-Marts three basic beliefs and rules that makes the store different from its competitors. However, Gilman (2004), Jones (1998), and Menzer (2001) give the reasons for the rate at which Wal-Mart is expanding in to the international market. They have a strong belief that Wal-Mart will dominate the US market in the future. A number of

Tax memo Essay Example | Topics and Well Written Essays - 500 words

Tax memo - Essay Example In the case of Acme Corporation and its shareholders, the redemption exercise may imply one or more tests, usually referred to as the three major tests. First is the complete redemption test. Here, there will be an absolute redemption of every stock possessed by the shareholder. Second is the substantially disproportionate test where the vending shareholder must not possess as much as 50 percent of the voting power following the redemption exercise. In addition, the owners voting stock in the company need to be not as much as 80 percent of the company’s aggregate voting stock after the redemption exercise. Third is what has been referred to as the â€Å"not essentially equivalent to a dividend test† (Ronald, 48). Here, the implication is that the redemptions need not be equal to the dividend issued by the company. It is important to note that the shareholder’s constructive, direct and indirect ownership can be considered in the above explained tests. If a shareho lder meets the above tests, the price that the company redeems the ownership will be treated like a normal exchange of sale and this will be recognized as if the owner was only passing this to another person or a third party. If the tests are not met, the company’s redemption price will be taken like the passing was made to another shareholder. Tax cost of a redemption to shareholders does start with if the transaction succeeds for sales or interchanged treatment, also Smith should confirm whether Acme Corporation has accrued return and earnings. If Acme does not have returns and earnings or the company has never acquired another company through merging, which had profit and earnings then the divided treatment cannot come into being from redemption. Normally dividends shared among its shareholders are usually treated as non-taxable return of capital to the point of accustomed foundation of stock, then capital growth from estimated nature of

Familial Hypercholesterolemia Term Paper Example | Topics and Well Written Essays - 2000 words

Familial Hypercholesterolemia - Term Paper Example The remaining cases of FH is caused by a mutation in the gene encoding for apolipoprotein B-100 (ApoB-100), located at the short arm of chromosome 2, which reduces ligand affinity for the normal receptors. As a result, plasma concentration of LDL-C increases (Al-Allaf, et al., 2010). The more common heterozygous FH is diagnosed by an average LDL-C level of greater than 160 mg/dl for two measurements (Jacobson, 2007). It is said that 1: 500 individuals suffer from it, more than those who have homozygous cystic fibrosis and sickle cell anemia. Typically, serum cholesterol is at 250-450 mg/dl (6.5-11.6 mmol/L) and LDL-C is at 200-400 mg/dl (5.2-10.4 mmol/L) (Al-Allaf, et al., 2010). Early intervention only warrants lifestyle changes, while therapeutics are needed in late cases where lifestyle modifications are already ineffective (Jacobson, 2007). On the other hand, the rare homozygous FH is characterized by total serum cholesterol levels of greater than 500 mg/dl (13 mmol/L) and LDL-C levels of greater than 450 mg/dl (11.7 mmol/L). It occurs in 1: 1, 000, 000 individuals. As a result of hypercholesterolemia, xanthoma on the tendons of the distal extremities and premature development of corneal arcus exist among individuals with homozygous FH. In addition, they develop cardiovascular diseases earlier relative to those with heterozygous FH (Al-Allaf, et al., 2010). FH carriers, on the other hand, are much more difficult to detect as they present with a wide variety of signs and symptoms (Broekhuizen et al., 2010). . There is no current treatment for the genetic mutation in FH, since studies on the effectiveness of gene therapy with surgical intervention are still ongoing (Al-Allaf, et al., 2010). However, if the signs and symptoms of FH are ignored, it can lead to premature fatal cardiovascular diseases, stroke and myocardial infarction (Daskalopoulou, Doonan and Mikhailidis, 2010). It increases the risk for hastened arterial plaque development, which normally begi n in early childhood and peak during adolescence (Jacobson, 2007). It is thus important to prevent these cardiovascular changes from happening so that better physical and social outcomes can be achieved and healthcare costs are minimized (Al-Allaf, et al., 2010; Broekhuizen et al., 2010). SUMMARY OF FINDINGS Approach on patient with hypercholesterolemia A person with high lipid levels is worked-up based on the stage of the disease at which presents. Hyperlipidemia in an otherwise healthy patient without family history of early myocardial infarct, stroke or peripheral vascular disease, only warrants basic lifestyle patient education regarding proper diet, exercise, and smoking prevention. Diet diary, food frequency questionnaire, and inquiries on usual food intake during the interview can illicit points at which dietary restrictions can be focused on. Meanwhile, if family history is present, fasting lipid profile is needed to determine whether average LDL-C is greater than 160 mg/dl, in which case the target LDL-C is set at below 130 mg/dl and therapeutic lifestyle changes (TLC) are advised (Jacobson, 2007). Non-pharmacological management In managing patients with FH, it is important to prioritize risk factors and to intervene them in a step-wise manner. In dietary modifications, decreasing intake of sources

Mini ethnography Research Paper Example | Topics and Well Written Essays - 1250 words

Mini ethnography - Research Paper Example Why is Sushi culturally significant to the Japanese community? The main hypothesis is to investigate the essence of Sushi among the people of Japan. According to the Japanese, Sushi is more than just raw fish meal as it also part of their history. The purpose for the research is to identify the traditional significance of sushi. In the investigation, the studying activity needs the use of qualitative information obtained from an interview, personal observation and reading archival information. The study uses a video camera to record the interview carried out, an iPad to record any observations and secondary information read. In order to obtain a more primary view of the key concepts, the anthropological study took place in Hokkaido, which is a town located in Hokkaido Island. Hokkaido Island is one of the four major Japanese islands. In Hokkaido town, there is a famous Japanese sushi restaurant known as Hokkaido Sushi Restaurant, where the Executive Chef, Mr. Thomas Kok was the main interviewee. Firstly, while at the town, especially the restaurant, most people including both locals and tourists, flocked into the hotel; all with the plan of having sushi. Secondly, most people enjoyed the meal especially, how the chefs designed it on the plate. Additionally, customers found it very delicious. Thirdly, the kitchen management consisted of only local citizens of the town; that is, Japanese. The chefs do not have hair on their arms or face. While eating, a person dips the fish into soy sauce before ingesting it. THOMAS KOK: Despite it being a renowned Japanese delicacy, sushi describes and reminds people of the ancient Japanese culture. Most of the ancestors were fishermen even before farming commenced. Therefore, it forms part of the ancient Japanese culture. THOMAS KOK: The hotel receives a large number of customers every day, all with the aim of eating sushi. Locals provide the largest market

Benefits of Video Games Research Paper Example | Topics and Well Written Essays - 2000 words

Benefits of Video Games - Research Paper Example Most institutions have installed computer laboratories to help their students to catch with the technology demanded by the contemporary job environment. Along this technology stands the gaming technology that continues to evolve and to become the favourite of many young students. In the invention of new video gaming technology, it was a mere source of entertainment that people could indulge to spend their luxury time. However, research has revealed that the value of video games in the life of learners has been ignored as these games can have both positive and negative impacts in their learning. Research points out that there is need for reconsideration of the application of video games in the life of learners both in their homes and in the school environment. Understanding the impact of video games on the learners learning will help to develop a strategy on which the negative effects can be eliminated and the positive can be optimized. Specifically, it will be possible to incorporate this technology in the learning environment and enhance the learners’ abilities. In this light, there is need to investigate the best approach to integrate computer aided video games in the curriculum. Video games have both physical and psychological impacts on the life of individual and this may affect their learning behaviour. Obradovic (2002) identifies that video games have had negative impacts on learners owing to the addictive behaviours that comes along their usage. As entertainment tools, video games are attractive and are addictive to their users statistics indicate that over 92% of children aged between 4 and 17 years have access to computer games and are likely to be addicts of playing these games. Addiction is the source of the negative impacts of the learning needs of the students. First, addiction comes about when a student spends

Final Review Assignment Example | Topics and Well Written Essays - 1000 words

Final Review - Assignment Example Crime is mostly viewed as an endurance alternative in the range of poverty (Pogrebin, 23). In contradiction to these expectations, some poor communities experiencing low levels of crime because behavior is restricted by unofficial social and cultural values. Unemployment is a vital issue related to the rates of crime and violence among most young people. From the World Bank research, people between the age of fifteen and 24 are not employed. This clearly suggests that the unemployed youths are probably more likely to be the beginners and victims of crime and violence. An abundance of universal information proposes that crime and violence are firmly connected with the development and extent of young populace and, particularly, youthful guys. Cross-national examination utilizing information on 44 nations from 1950 to 2000 uncovers the rate of youthful individuals in the populace and their level of flourishing are together more critical in illustrating the variability of crime. The incr ease in the number of youths is clearly evident in the story of the killer Louis Wagner was executed on June 25, 1875. This is as a result of the increased love affairs within the young people. In March of that year on the Isles of Shoals (Smuttynose, particularly), two adolescent Norwegian ladies were clubbed to passing. Wagner, a 28-year old Prussian worker, appeared to have no true rational in murdering the two ladies. In spite of the fact that commentators have addressed her observer account, it was Maren who recognized the executioner as Louis Wagner (Capote, 317). A neighborhood angler considered his dory lost from Pickering Wharf close-by at 8 p.m. also it is presently expected Louis obtained it. His eleven hour nonattendance furnishes adequate time for the excursion under existing quiet climate conditions (Pogrebin 39). The tide was in his support the moon was bright and the White Island beacon plainly indicated the way. Maren affirmed that a passing angle had conveyed her s pouse's message maxim he might return extremely late. The trail of blood persuaded the jury that the executioner was acquainted with the Hontvet house. Not long after his capture, in a statement, Louis Wagner had dissented that he was so acquainted with the Hontvet house that, if he truly need to burglarize them, he could have completed it effortlessly and without discovery. Indeed Louis Wagner's passing is wrapped in false impressions. Either way this was a violent action and a crime. Unemployment can lead to human beings carrying out extremely violent and criminal acts as shown in the True Crime: An American Anthology. The high minded man is substance to dream what a devilish man truly does." I considered this entertaining, for no other excuse for why than Schechter appeared to be possibly on the edge, which is a position that any correct crime spectator will in the long run end up enclosed. You take it that individuals will ask you for what reason you would at any point need to r ead such shocking things the Crime. In this segment, the crime is depicted. This could be carried out in two ways (Schechter 339). To begin with, the crime could be depicted as a story. Then again, and this is more common, you can portray the crime scene, then loop once again to the genuine crime as a flashback later in the book as Capote does with Perry Smith's extremely popular jailhouse admission. Chase for the executioners.

Women Essay Example for Free

Women Essay In the persuasive paper, the issue of abortion through a Feminist perspective and ethical lens will be looked into. Much controversy surrounds the issue but looking at feminist theory, more specifically, radical feminist theory, the decision for a woman to abort should be available if needed. Not only that, but the decision should be left up to the pregnant woman and the pregnant woman only, as this is seen as a form of escaping male dominance in society. The main arguments that will be used within the paper are: most importantly the feminist perspective of abortion, a feminist perspective of a woman’s control over her sexuality and how this relates to abortion, birth control, and lastly the reasoning behind why women may choose to abort. The writing style the persuasive paper will follow is APA style, and the following are a list of scholarly sources that will be used: 1.Himmelweit, S. (1980). Abortion: Individual choice and social control. Feminist Review, 5(1), 65-68. doi: http://dx.doi.org/10.1057/fr.1980.13 is one of the sources that will be used in the persuasive paper. The journal informs and a report on original research, as well as it provides an analysis of issues specific to the discipline. These two reasons demonstrate a purpose of publication which clearly indicates that this is indeed a scholarly source. 2. Zampas, C., Gher, J. M. (2008). Abortion as a human right—international and regional standards. Oxford Journals, 8(2), 269-294. doi: 10.1093/hrlr/ngn008 is another source chosen to be used within the paper. Frequency of publication is often a good indication that a source is in fact scholarly. Often quarterly is a good forewarning of a scholarly source, which Oxford Journals is credible for. 3. Bridgeman, J. (2011). Wise women in community: building on everyday radical feminism for social change. Interface, 3(2), 288-293. Retrieved from http://www.interfacejournal.net/wordpress/wp-content/uploads/2011/12/Interfac

Identifying Bacteria Essay Example for Free

Identifying Bacteria Essay Bacteria identification is accomplished in a number of ways. Two common tools microbiologists use to identify unknown bacteria include dichotomous key and biochemical tests. The dichotomous key is useful when a microbiologist only needs to know which group an unknown microbe belongs to on a general level. When a microbiologist needs to identify a specific bacterium, biochemical tests are used. PART ONE: GENERAL BACTERIA IDENTIFICATION Review the dichotomous key in Figure A, the bacterial shapes in Figure B, and the Gram stain information below. You will use all three to determine to which major group unknown bacteria belong. Gram Stain Results: Purple = Gram positive Red = Gram negative Neither purple nor red = No cell wall (neither Gram positive nor Gram negative) Review Figure C on the following page. Use Figure C to identify the type of arrangement displayed by the unknown bacteria. Read through the Sample Identification on the following page for an example of how to identify bacterial groups and arrangements using Figures A, B, C, and the Gram stain results. Sample Identification After performing a Gram stain, you observe the following under a microscope: (Cells are stained red.) Begin with item 1 on the dichotomous key (Figure A). Because the organisms  are red, they are not Gram-positive. According to the key, continue to item 3. Because the organism is red (not clear or another color), it is indeed Gram-negative according to item 3. The key directs you to item 5. Consider the shape of individual cells for item 5. According to Figure B, the shape type is closest to spherical. (Note: spherical is circular.) The bacteria belong to the Gram-negative cocci group. Now use Figure C to describe arrangement of bacteria. (The bacteria are not rod- or club-shaped, so focus on the cocci arrangements.) Identify the arrangement that is most prominent. The bacteria are arranged in a diplo- fashion. Enter the group and arrangement in the table. Application Use Figures A, B, C, and Gram stain results to identify group and arrangement of bacteria. Continue to Part Two after completing the table. View from Microscope Group of Bacteria Arrangement (stained red) Gram-negative cocci Diplo- (stained purple) (stained purple) (stained red) (stained red) (stained purple) (stained purple) PART TWO: CAse study scenario: identify specific bacteria through biochemical testing To gain an understanding of the processes involved with identifying bacteria through biochemical tests, access Chapter 6 of the text in WileyPlus located on the Week One course page. Once in WileyPlus (Chapter 6), select the â€Å"Bacterial Identification by API† link located under the heading, Take Another Look. Once selected, review the information and watch the Flash-animated movie (animation) located within this link. Then, review the following scenario and answer the questions that follow. Case Study A recent outbreak of food poisoning has occurred in a community. One possible source of contamination may be the produce that is grown and distributed locally at a farmer’s market. A test sample of some of the produce revealed evidence of bacterial contamination. The bacteria sample was tested in a microbiology lab and showed the results that follow. The laboratory also performed a Gram stain of the isolated bacteria and ran a number of biochemical tests to aid identification. The biochemical tests were assayed using the Analytical Profile Index (API) 20E system for identification of Enterobacteriaceae and other gram-negative bacteria. Figure 1. Microbiology laboratory results – Unknown bacteria present on produce (API Results) Figure 2. API Results of Unknown Bacteria in Text Format Gram stain: Gram-negative Based on Gram stain results and the knowledge that this bacterium caused food poisoning, the laboratory is able to narrow down the possibilities to three bacterial strains. Figure 3 shows the API results: Figure 3. API Results of Known Bacterial Strains in Text Format Gram stain Application Compare the API biochemical test results in Figure 2 (unknown bacteria from  produce) with API test results in Figure 3 (known bacterial strains identified in the gray boxes on the left). The bacterial strain in Figure 3 that matches Figure 2 will identify the bacterial strain causing illness. Based upon your observations, which of the bacteria in Figure 3 is the most likely cause of the food poisoning outbreak?