Project Design Plan Essay Example for Free

Project Design Plan Essay This experiment is to test the theory that the temperature of water affects the duration of time it takes to water to reach freezing? Hot water freezing faster than cold has been observed for many centuries. The earliest known reference to this effect is by Aristotle, who wrote: The fact that water has previously been warmed contributes to its freezing quickly; for so it cools sooner. Hence many people, when they want to cool hot water quickly, begin by putting it in the sun. . . (Jeng) Literature review 1. According to a study of the Mpemba effect by Monwhea Jeng Many factors impact water as it cools and eventually freezes, evaporation can contribute to a loss of mass, Hot water can hold less dissolved gas than cold water and large amounts of dissolved gas escape upon boiling, convection currents and non-uniform temperature distribution happen as water cools, the environmental of the hot sample also impacts the environment around it. Super cooling may also have an important role in the effect, super cooling occours when water freezes not at 0c but at some lower temperature. (Jeng, The Mpemba effect: When can hot water freeze faster than cold? , 2006) 2. In 1963 a student named Erasto B Mpemba noticed that placing recently a recently boiled mixture of milk and sugar into the refrigerator it froze into ice-cream faster than another students mixture that was not heated. He asked his physics instructor why this had happened and his physics instructor informed him â€Å"you are confused, that cannot happen† this response highlights the need for objectivity in scientific studies. After repeatedly asking various instructors to explain his observations Mpemba took two 50ml beakers and filled one with water from the tap and one from hot water from a boiler and put them into a freezer, after an hour he discovered that their was in fact more ice formation in the sample from the boiler. Dr Osborne visited the school where Mpemba studied and Mpemeba asked him to explain the effect, he could not but unlike previous instructors and peers Dr. Osborne conducted experiments and did infact repeat Mpemba’s discovery (Osborne) Variables The Dependent variable is the starting temperature of the water being placed into the freezer. The Independent variable time elapsed until each sample freezes The Controlled variables are temperature of the freezer, the volume of the water samples and the sample containers. Hypothesis My hypothesis is that the hot water will freeze in a shorter elapsed time than the cold water due to a combination of loss of volume during the heating/cooling process; I arrived at this hypothesis through researching the Mpemba effect and reviewing the results of other experiments. Experimental design After reading multiple possible ways to conduct experiments on the Mpemba effect I chose this design plan because the experiment could be conducted with supplies I had on hand and should be easily reproducible. I will measure the temperature with a common digital kitchen thermometer every fifteen minutes until the water sample has frozen solid enough that the thermometer cannot penetrate the ice to take measurements. The tools I will be using are 1 Plastic measuring cup,1 Thermometer, Two .30 l plastic storage containers,1 Kitchen timer, 1 Clock, 1 Range cook top, 1 Sauce pan. Threat Reduction to Internal Validity To reduce the threats to internal validity I will use the same procedure’s to objectively measure the variables of temperature and volume in my experiment. Each temperature reading will be taken using the same thermometer; each volume measurement will be taken using the same measuring cup. Identical storage containers will be used to store the water samples and they will be placed at the same time into the same freezer on the same bare shelf. Experimental procedure. Step 1 Draw two samples of tap water 250ml each and record initial temperature Step 2 pour one sample into sauce pan heat to boiling; pour other sample into .30 l plastic storage container Step 3 pour boiling  sample into measuring cup and note any loss of volume Step 4 return samples to .30l plastic storage container Step 5 measure temperatures of boiled sample and room temperature sample Step 6 place both .30l plastic storage container into freezer Step 7 measure temperature of both samples every 15 min logging results until both samples are held at or below zero degrees Celsius long enough that the thermometers temperature probe cannot pierce the surface of the sample. . Step 8 Allow both samples to thaw at room temperature and measure for any loss of volume Experiment Results In my investigation the boiled sample of water did in fact freeze faster than the colder tap water sample the greatest temperature differential during my experiment arrived in the first 15 minutes of the boiled sample being introduced to the freezer, the boiled sample entered the freezer at 99.6C and 15 minutes later the temperature was 18.1c this represents a reduction of 81.5 degrees. No notable change of temperature to the environment was recorded. The cold sample also experienced the greatest reduction in temperature in the first 15 minutes of my experiment with a starting temperature of 14.3c and 15 minutes later the temperature was 2 degrees Celsius The hot sample continued to lose heat faster than the cold sample until 120 min into my experiment where both samples reached -0.6c and were too solidly frozen to continue measurements. After both samples were too solid to continue measurements I removed both samples from the freezer and allowed them to thaw once both samples were thawed I measured the remaining water volume the hot sample lost 30% of its volume whereas the cold sample had only lost 10% Conclusion This experiment has proven my hypothesis the hot water sample did in fact freeze in a shorter elapsed time than the cold water. The hot sample also lost 30% of its volume. The experimental design was a key factor in proving my hypothesis as it controlled many of the variables that could impact the outcome of my investigation. To replicate my experiment you will need a thermometer 500ml of water, two identical storage containers and a freezer with a constant temperature of 18 degrees Celsius . I replicated my experiment using the same experimental procedure and achieved the same results with a slight variation in the loss of volume in the hot sample, in my second attempt the hot sample lost 35% of its volume. Because I achieved similar results using the same experimental design I believe my observations are valid. Works Cited Jeng, M. (n.d.). Retrieved from http://math.ucr.edu/home/baez/physics/General/hot_water.html#History Jeng, M. (2006). The Mpemba effect: When can hot water freeze faster than cold? . American Journal of Physics, 514. Kurtus, R. (n.d.). Retrieved from http://www.school-for-champions.com/science/mpemba.htm Osborne, E. M. (n.d.). Retrieved from http://www.rsc.org/images/Cool-Mpemba-Osborne1969_tcm18-222099.pdf

GCSE English Coursework Essay Example for Free

GCSE English Coursework Essay My room was dark, you could barely see the hands reaching out to grab you in your dreams, all you heard were the screams echoing down the hallway, the fury behind them, and the angered blood lust churning to be free from its mortal outer-shell. Then it all changed, he came for you after that, his sodden pitch black trench coat and his face so pale he looked as if he was a ghost; his eyes so red from all the built up torment. Then there were his teeth, he looked like a demon, yet his teeth were immaculate, a pristine definition of some good that was left in his heart, but from ones soul there is always something, lurking, slunk down in the hidden depths that is waiting there to turn evil. He seemed to enjoy his job, the chaotic screams of his victims bellowing, throughout, he endured fatalities, he loved to see them although the only thing he wouldnt let you do, was die, he expected you to live through your curse until you were freed. The only problem was, you could never leave, once you made an agreement with the brotherhood they expected payment and if you didnt, you end up being taken to this place; there they would extract their blood money. My name My name no longer exists; the brotherhood snatches everything you have to keep, including your identity. I have always been prisoner 101, sometimes I do wish I could go home though, see my family again, enjoy the holidays, and have a life. I expect you are wondering how I got here, well, it all started when I was 14, my friends and I were having a laugh and decided to explore this run-down windmill by the old orchard, that was supposedly haunted and apparently home to a witch. Being kids, this is something you believed and you would dare each other to go up to it. I had to go into the windmill and find some proof that there was something that there, and there it began, I slowly opened the door and clambered in, unaware of what was to come, I began to climb the winding staircase and as I reached the top there was something Something strange and peculiar; a girl, just standing there, looking over the edge, past the rotating blades and beyond the field, as if there was something to see in the blackness. As she turned round to look at me I saw nothingness in her gaze, no emotion, not a feeling, she looked right through me. She didnt look much older then me, she had long, dark hair and a pasty white face, she had a blank sense about her, it seemed she didnt know where she was or who she was, I asked her, her name but she didnt reply, she just kept on swaying from side and humming , she looked like the dead, she smelt like it too, I kept on asking her questions so I could get a response from her but finally she answered to me, she shouted at the top of her voice, it had a frightened feel to it as she was stuttering and trembling. They are coming. She said I was trying to say to her Who was coming? and Why are you crying? She just kept on saying it but getting more shaky and slower, until suddenly She stopped; petrified with horror, her eyes began to fix and then I began to feel something was wrong, I saw her eyes begin to slowly move until they were fixed on something forming a shape behind me. I knew from that point on there was something materialising behind me. I sensed its darkened gaze looking at me and its breath beating on my head, and thats when I saw him for the first time. As I turned to look behind me, there he was, looking down on me, his sodden, black trench coat, his eyes looking deep inside me and his sharp white teeth glinting at me in a murderously smile that sent shivers down my spine. I started walking backwards to stand next to the girl to have some company, but he kept coming closer towards me, the stench about him made me want to throw up, he slowly lifted his arm and stretched out his crocked finger and pointed at me, You have a debt to pay Said he. As I came up to the girl she looked at me once, then began to turn away again and look over the fields, she began to hum again a tune of which I never heard, this mysterious figure placed his cold hands on my shoulder, and then I saw something appear behind him, he grasped his hands onto me and threw me into the shape, both figures following behind me until I landed onto a cold flag stone, it was slimy to the touch and smelt vile, when I got a beam on moonlight shine down upon me, I realised I landed into a pit, the coagulated blood filled my sinuses with the stench of death and the ever-staring eyes watching me all over

La-Mg-Ni Based Alloys

La-Mg-Ni Based Alloys Abstract: Degradation behaviors of La2MgNi9, La1.5Mg0.5Ni7 and La4MgNi19 alloys were studied. The results indicate that severe pulverization and corrosion are important factors leading to the capacity deterioration. However, it is puzzled that corrosion of the electrochemical cycled alloys is aggravated, which is inconsistent with the result that La2MgNi9 present poor cycling stability andalso the assumption that alloy with high Mg content is easy to be corroded. Then, the intrinsic anti-corrosion and anti-pulverization characteristics were mainly focused in the first part of this work. Immersion experiments demonstrate that the Mg-rich phases are more easily to be corroded. The intrinsic anti-corrosion resistance of the three alloys presents an improved trend which is inversely proportional to the abundance of the Mg-rich phases. However, the intrinsic anti-pulverization ability just presents an inverse trend, which is closely related to mechanical property of the phase structures. LaNi5 with the highest hardness is easy to crack, but the soft (La,Mg)Ni2 is more resistant to crack formation and spreading, suggesting a possibility to improve the anti-pulverization ability by adjusting the phase constitution. In general, the weaker corroded extent of La2MgNi9 in the electrochemical test is attributed to its better intrinsic anti-pulverization capability though the intrinsic anti-corrosion of La2MgNi9 is worse. As to La4MgNi19 which possesses excellent intrinsic anti-corrosion resistant, enhancement of the anti-pulverization ability is the key issue to improve the cycling stability. 1 Introduction Superlattice La-Mg-Ni based hydrogen storage alloys have received substantial attentions over the last decade because the excellent electrochemical performances used in nickel/metal hydride (Ni/MH) battery [1-5]. Up to now, A2B7 type alloys have been successful developed for the practical use [3]. However, AB2 and AB3 type alloys present poor cycling stability though the theoretical discharge capacities are higher than A2B7 type alloys [6-8]. In addition, A5B19 type alloys have been reported to possess good electrochemical performances, but they still need improvement to meet the practical application, especially on the cycling stability in the long-term reversible cycles [9-10]. It is well accepted that electrochemical capacity decrease of the metal hydride electrodes is caused by both the physical and chemical degradation [11-12]. In La-Mg-Ni system, factors affecting the capacity degradation were emphasized on pulverization and corrosion during the charge/discharge cyclings [13-17]. Corrosion leads to damage and disappearance of the phases which possess considerable hydrogen storage capacity. It has been reported that La-Mg-Ni alloys are easily to be corroded into La(OH)3 and Mg(OH)2 [13-15]. And these kinds of corrosion products are loose and passive which cannot protect the matrix for further corrosion [15-16]. Severe pulverization of La-Mg-Ni alloys during cycling had also been reported in many works [13-17]. Pulverization makes fresh surface of the electrodes alloys continuously exposed to the electrolyte and dramatically improves development of corrosion. Liu et al. classified the degradation process of the La-Mg-Ni-Co alloy into three stages: the pul verization and Mg oxidation stage, the Mg and La oxidation stage and the oxidation and passivation stage [14]. In addition, capacity degradation of the metal hydrides is closely related to the structural changes during absorption/desorption cycling. Our previous works demonstrated that transformation from crystallinity to amorphous viz. hydrogen induced amorphization (HIA) of La-Mg-Ni alloys occurred during the hydrogenation cycles and remarkably worsens both the gas-solid and electrochemical storage performances [18-19]. Understanding of the degradation mechanisms is the precondition for improvement of the cycling stability of the La-Mg-Ni based alloys. Several compounds including AB2, AB3, A2B7 and A5B19 type phase exist in this system, and the alloys usually present multi-phase microstructure. Though quiet a number of efforts have been applied on the degradation characters of the La-Mg-Ni based alloys, these works mainly focused on the overall capacity deterioration behaviors of the alloys. Diversity of the degradation characteristics of various compounds in this system is also lacking. In the present study, degradation mechanisms of three typical La-Mg-Ni alloys: La2MgNi9, La1.5Mg0.5Ni7 and La4MgNi19 have been systematically investigated. In the first part of this work, corrosion and pulverization behaviors of the alloys, especially the intrinsic characteristics of the AB3, A2B7 and A5B19 type La-Mg-Ni phases during absorption/desorption cycling were generated. In a following paper, HIA and its in fluence on the hydrogen storage properties are discussed. 2 Experimental materials and methods 2.1 Alloy preparation The as-cast La2MgNi9, La1.5Mg0.5Ni7 and La4MgNi19 alloy was prepared by induction levitation melting under argon atmosphere. The as-cast alloys were remelted twice for homogeneity. Appropriate excess of Mg was added in order to compensate for the evaporative loss of Mg during melting. Then the as-cast La2MgNi9, La1.5Mg0.5Ni7 and La4MgNi19 alloys were annealed at 1143, 1173 and 1193 K respectively for 6 h protected in argon atmosphere. 2.2 Characterization The sample was fine polished and then etched using a mixed etchant (including water, ethanol, acetic acid, picric acid, nitric acid and hydrochloric acid) at 343K. Then metallographic microstructure of the alloys was observed using a laser scanning confocal microscope (LSCM: Olympus-OLS4000). Phase constitution of the alloys was also characterized by a scanning electron microscopy (SEM: FEI-Qanta 400) under backscatter electron mode (BSE) applied on the unetched samples. The chemical composition of various phases was studied by energy dispersive spectroscopy (EDS) equipped in the SEM. Crystal structures of the alloys were measured by an X-ray diffractometer (XRD: Bruker-D8 Advance) with Cu KÃŽÂ ±1 radiation. Micro-morphologies and selected area electron diffraction (SAED) were applied by means of a transmission electron microscopy (TEM: JEOL-2100 and FEI-F20) to examine the microstructural and crystallographic information. TEM samples were firstly crushed the bulk into fine powder , and then ultrasonic dispersion was performed in ethanol for 1800 s. Several drops of the mixed liquid were laid on a carbon membrane support on the copper grid, and dried in a vacuum oven. Particle size of the cycled alloys was tested by a laser particle size analyzer (Malvern-Mastersizer 3000) where the alloy particles were dispersed by absolute alcohol. Oxygen content of the electrochemical cycled and immersed alloys was performed on a nitrogen/oxygen tester (NCS-ON3000). Before the oxygen test, samples were immersed in deionized water for 24 h, then washed using absolute alcohol twice to remove the residual KOH, and dried in a vacuum drying oven. 2.3 Hydrogen storage properties Gas-solid cycling and PCT isotherm measurement were carried out by Suzuki -2SDWIN PCT system at 303K (Sieverts type). Before the PCT analysis, sample was activated as follow: evacuated at 473 K for 2 h, placed to 303K, hydrogenated under 3Mpa H2 (Purity 99.999%) pressure for 5 h, evacuated at 573 K for 2 h again. Each cycle consists of absorption at 2MPa for 600s and desorption by evacuating at 298K for 1200 s. For the electrochemical measurement, the alloy particles (40-50 µm) were mixed with carbonyl nickel powder in a weight ratio of 1:5 and cold pressed to form a pellet about 1g firstly. The pellets were then packed in a Ni foam substrate spot-welded with a Ni strip. The simulated three-electrode cell including a working electrode (metal hydride), a counter electrode (NiOOH/Ni(OH)2) and a reference electrode (Hg/HgO) was installed. Before electrochemical test, the alloy metal hydride electrode was immersed in 6 M KOH aqueous solution for 1d. The measurement to get the maximum capacity and cycling stability was to charge at current density of 105 mA/g for 4h followed by a rest of 10min, then discharged at the same current density to the cut-off voltage of -0.6 V. 3 Results and discussions 3.1 Microstructure and hydrogen storage performances LSCM and BSE micrographs of the three alloys are shown in Fig.1. Four contrasts can be detected in the La2MgNi9 alloy. The chemical quantitations of various contrast from EDS analysis are listed in Table 1, from which the four phases are speculated to be (La,Mg)Ni2, (La,Mg)Ni3, (La,Mg)2Ni7 and LaNi5. Five crystal structures including CaCu5-type, MgCu4Sn-type, PuNi3-type, Ce2Ni7-type and Gd2Co7-type are identified in XRD profile of the La2MgNi9 alloy, as shown in Fig.2. The structural parameters and phase abundance are refined and listed in Table 2. The results are in consistent with the metallographic observation that the main phase is (La,Mg)Ni3, then (La,Mg)Ni2and (La,Mg)2Ni7, but content of LaNi5 is rare. In case of the La1.5Mg0.5Ni7 and La4MgNi19 alloy, metallographic and XRD characterization indicate that (La,Mg)Ni2disappears, (La,Mg)5Ni19 emerges and LaNi5 increases with elevation of the B-side stoichiometry. The main phase of the La1.5Mg0.5Ni7 and La4MgNi19 alloy is (La,Mg)2Ni7 and (La,Mg)5Ni19 respectively, and the structural parameters and phase abundance are also listed in Table 2. Fig.3 displays P-C-Tcurves of the alloys, and the detailed data are given in Table 3. Theoretically, hydrogenation capability increases with reduction of the B-side stoichiometry in the La-Mg-Ni based alloys. However, the maximum hydrogen absorption content of the La2MgNi9 alloy is slightly lower than the La1.5Mg0.5Ni7 alloy. It is ascribed to the fact that some (La,Mg)Ni2 which can hardly absorb and desorb hydrogen at room temperature [8], existing in the La2MgNi9 alloy. The three alloys have analogic hydrogen absorption plateau. But both the desorption pressure and the reversible hydrogen capacity elevate with increase of the B-side stoichiometry of the three alloys. Reversible hydrogen capacity of the AB3-typed La2MgNi9 alloy is only 1.15 wt%, and the hysteresis effect is more evident than the other alloys. Electrochemical discharge curves and performances of the alloys are shown in Fig.4 and Table 3 respectively. Discharge capacities of the La2MgNi9 and La4MgNi19 alloy are lower than the La1.5Mg0.5Ni7 alloy. The lower discharge capacity of La2MgNi9 is due to the weak reversible hydrogen storage capacity. As to the La4MgNi19 alloy, it is attributed to high abundance of LaNi5 which is unsuited for the electrochemical application without alloying [20]. Furthermore, La1.5Mg0.5Ni7 presents better cycling stability than the other two alloys. Capacity retention after 100 cycles of the La2MgNi9 alloy is similar with that of the La4MgNi19 alloy. 3.2 Degradation characteristics after electrochemical cycling From morphology and EDS results of the alloys, it is clear that pulverization and corrosion have occurred after electrochemical cycling by 100 times (only La2MgNi9 alloy presents in Fig.5). XRD analysis shows that La(OH)3, Mg(OH)2 and La2O3 appear in the cycled alloys, as displayed in Fig.6. Likewise, morphology and SAED analysis of TEM confirm existence of La(OH)3 combined with La2O3 (stick-like), Mg(OH)2 (needle-like) and MgO (particles), which are marked with 1, 2 and 3 respectively as illustrated in Fig.7. The results are in consistent with the other literature studied on the corrosion products of a La1.5Mg0.5Ni7 alloy [21]. Detailed determinations of TEM are provided in the supplementary information (Fig.S1-S3). In addition, size and amount of La(OH)3 and La2O3 are obvious than that of Mg(OH)2 and MgO, indicating that corrosion of La is significant in the electrochemical environment. Mg(OH)2 and MgO are close to the alloy surface but very loose. It agrees well with the previous works that corrosion products of Mg are gel-type and cannot form a solid protection layer for further corrosion [15-16]. Compared among the three alloys, it is noteworthy that corrosion productions of the La2MgNi9alloy are less than the other alloys (see in Fig.6). Identically, oxygen contents of the electrochemical cycled alloys follow the order that La2MgNi9 1.5Mg0.5Ni7 4MgNi19, indicating that the corroded extent are aggravated (see in Fig.8). It is puzzled that the result is inconsistent with the electrochemical performances that La2MgNi9 possesses poor cycling stability. It also disagrees with the consideration that high Mg content is harmful to the corrosion resistance in La-Mg-Ni based alloys [22-24]. In order to comprehend this fact further, the intrinsic anti-corrosion resistance of the three alloys was investigated next. 3.3 The intrinsic anti-corrosion properties To avoid impacts of pulverization on the corrosion behaviors, the alloy particles with the same diameter (around 40 ÃŽÂ ¼m) were immersed in KOH solution at 60  °C for 15 d. Then the morphology, phase structure and oxygen content were measured for characterization of the intrinsic corrosion behaviors. SEM micrographs and EDS analysis of the alloy particles illustrate that severe corrosion occurred after immersion, the typical results are shown in Fig.9 (only La2MgNi9 alloy particles are given here). Compared to the electrochemical cycled alloys, the stick-like products which have been confirmed as composite of La(OH)3 and La2O3, are remarkable in the immersed samples which is due to aggravated corrosion at higher temperature. XRD profiles identify that the corrosion products are mainly La(OH)3, but La2O3 cannot be detected in the immersed alloys, as shown in Fig.10. Coincidently, SAED by TEM found that the stick-shaped phase is single-phase La(OH)3, as shown in Fig.11. The result suggests that La2O3 transforms to La(OH)3 during evolution of the corrosion process. Besides, Mg(OH)2 and MgO are also found existing in the immersed samples, and their morphologies are same with that in the electrochemical cycled alloys. However, Mg(OH)2can only be detected in La2MgNi9 from the identifications of XRD, indicating that corrosion of Mg is violent in La2MgNi9. Fig.12 is the oxygen contents of the immersed alloys, from which severity of corrosion of the three alloys are La2MgNi9 > La1.5Mg0.5Ni7 > La4MgNi19. To provide detailed information of the relationship between the corrosion behaviors and phase constitution, immersion test applied on the massive samples has also been studied (the condition is same with that of the powder samples). Fig.13 shows the SEM-BSE micrographs of the immersed samples (only La1.5Mg0.5Ni7 alloy are present here). Obviously, the corroded extent is inhomogeneous which is considered to be caused by differences of the anti-corrosion capabilities of the various phases. EDS analysis on two regions with diverse corrosion grades (as marked with 1 and 2 in Fig.13) shows no Mg but less O existing in region 1. Whereas, more Mg and O are detected in region 2 with severe corroded extent than region 1. Likewise, EDS-mapping indicates that the region possessing more Mg presents richer O, as shown in Fig.14. Similar result is more evident in the as-cast alloys, which is attributed to the inhomogeneous chemical composition and microstructure of the as-cast alloy, details can b e seen in the supplementary (Fig. S4 and S5). The aforementioned results demonstrate that the Mg-rich phases are easy to be corroded in the alkaline solution. It has been well demonstrated that Mg solubility in La-Mg-Ni alloys follows the order that (La,Mg)Ni2> (La,Mg)Ni3 > (La,Mg)2Ni7 > (La,Mg)5Ni19 > LaNi5 [25]. Thus the intrinsic anti-corrosion resistances of various phases in the La-Mg-Ni system are considered to be according with the inverse trend. This result is in agreement with several works where AB2and AB3 type La-Mg-Ni alloys have suffered serious corrosion after electrochemical experiments [8, 23-24]. The tendency is also exactly identical with that the anti-corrosion resistance is inversely proportional to the abundance of the Mg-rich phases. La2MgNi9 presents worse anti-corrosion capability because contents of the Mg-rich (La,Mg)Ni2and(La,Mg)Ni3 arehigher thanthe other two alloys. However, trend of the intrinsic anti-corrosion resistance is opposite to the corrosion extent of the three alloys after electrochemical cyclings. Concern to the fact that corrosion extent of the electrode alloys is also closely related to severity of pulverization during the electrochemical charge/discharge process, the pulverization properties of the alloys are carefully characterized then. 3.4 The intrinsic anti-pulverization properties In order to avoid influence of the additives in the electrochemical test on characterization of the intrinsic pulverization behaviors, the alloys are gaseous hydrogenated and dehydrogenated for 30 cycles. Morphology observation indicates that remarkable pulverization has occurred where decrease of the particle size and emergence of cracks can be seen clearly in the cycled alloys, as shown in Fig.15 (only La2MgNi9 alloy are present here). Then the particles sizes before (Sb) and after (Sa) cycling are measured and the size retention is calculated by Sb/Sa. It (Fig.16) shows that severity of pulverization for the three alloys are La2MgNi9 1.5Mg0.5Ni7 4MgNi19, which is just contrary to the tendency of the corrosion extent after the immersion experiment. Combined with the results of the intrinsic anti-corrosion and pulverization characterization, we can conclude that the weaker corrosion extent of La2MgNi9 in the electrochemical test is attributed to its better intrinsic anti-pulverization capability though the intrinsic anti-corrosion of La2MgNi9 is worse. It has been well accepted that pulverization is induced by the cell volume expansion upon hydrogen absorption [11-12]. Thus, large volume change leads to severe pulverization. Unfortunately, exact measurement of the volume expansion in the present work is difficult due to the multi-phase microstructure. Instead, we summarize the volume changes according to other experimental works where microstructures of these alloys are all sing-phase to ensure the accuracy as far as possible. Based on the data as listed in Table 4, there is no regular trend for the volume changes among the various structures in La-Mg-Ni system. And, no special relationship between the reported volume expansion data and the pulverization performances in the present work can be found. Besides, pulverization is believed to depend on the mechanical properties of the alloys [11-12]. Alloys with the more ductile character are more resistant to pulverization than the brittle materials. Usually, hydrogen storage alloys ar e hard and brittle, thus measuring ductility directly is difficult. Alternatively, Vickers hardness has been used to evaluate the preference of pulverization for the hydrogen storage alloys. And, previous works have found an almost inverse relationship between Vickers hardness and the pulverization rate [11-12, 30], suggesting the availability of Vickers hardness measurement on characterization of the anti-pulverization ability. Fig.17 gives indentations of the various phases in La2MgNi9 and La1.5Mg0.5Ni7 alloy. Evolution of Vickers hardness can be seen in Fig.18. It presents a linear relation between the Vickers hardness and B-side stoichiometry of the structures, which also agrees well with the pulverization behaviors of the alloys. Obviously, the mechanical property is an important factor affecting the anti-pulverization ability in the La-Mg-Ni phases. It is found that hardness differences of the AB3, A2B7 and A5B19 type phase are small. Under low loading of the hardness test, micro-cracks can hardly be observed in all the above three phases. Since the test force increase, micro-cracks can be seen in all these phases, but there is no obvious difference between them. Differently, LaNi5 is the hard phase, but hardness of (La,Mg)Ni2 is far more lower than the other phases. To comprehend more understanding on the crack formation of various phases, a massive sample with a polished surface was partial charged by electrochemical method, and the morphology and distribution of crack was observed. To highlight character of the hard and soft phase, the as-cast La2MgNi9 alloy was selected for the high abundance of LaNi5 and (La,Mg)Ni2. Microstructure characteristics of the as-cast La2MgNi9 alloy are given in the supplementary (Fig.S6-S7). As shown in Fig.19, quite a number of cracks can be observed in the sample which is only charged for 10 min. Most of the cracks exist in LaNi5 with the darkest contrast in the BSE image. One reason is that LaNi5 is the catalytic phase that primarily charged in the La-Mg-Ni system [31-32]. More importantly, it also ascribes to the brittle character of LaNi5 which agrees well with the above result that the hard phase is easy to crack formation. It is noteworthy that cracks are often stopped in front of (La,Mg)Ni2. Obviously, the soft phase is more resistant to crack formation and able to prevent the crack spreading. Similar result has been reported in other literatures where ductile secondary phases are believed to be beneficial to the cycling stability [33]. According to the above results, we can conclude that La4MgNi19 alloy is easy to pulverization as the high abundance of the hard phases LaNi5 and (La,Mg)5Ni19. As to La2MgNi9, little LaNi5 but existence of the soft (La,Mg)Ni2 and (La,Mg)Ni3 make it more resistant to crack emergence. These findings enlighten a way to improve the anti-pulverization ability by introduction appropriate abundance and distribution of soft secondary phases. 4 Conclusions In the present study, corrosion and pulverization behaviors of three typical La-Mg-Ni alloys: La2MgNi9, La1.5Mg0.5Ni7 and La4MgNi19 have been systematically investigated. All the alloys present multi-phase microstructure with (La,Mg)Ni3, (La,Mg)2Ni7and (La,Mg)5Ni19 as the main phase respectively. La1.5Mg0.5Ni7 possesses better electrochemical properties among the three alloys. It is found that pulverization and corrosion with the main product La(OH)3, combined with La2O3, Mg(OH)2 and MgO, have occurred after the electrochemical cycling. The overall corrosion extent of the electrochemical cycled alloys follow the order that La2MgNi9 1.5Mg0.5Ni7 4MgNi19. Immersion test demonstrate that the Mg-rich phases are easy to be corroded in the alkaline solution. The intrinsic anti-corrosion resistance are found to be La2MgNi9 1.5Mg0.5Ni7 4MgNi19, which is inversely proportional to the abundance of the Mg-rich phases. However, the intrinsic anti-pulverization ability just presents an inverse tre nd that La2MgNi9 > La1.5Mg0.5Ni7 > La4MgNi19. It is found that the mechanical property is an important factor affecting the anti-pulverization ability. Vickers hardness elevates with increase of the B-side stoichiometry of the various phases, which agrees well with the pulverization behaviors of the alloys. Furthermore, LaNi5 with the highest hardness is found to be easy to crack formation, but the soft (La,Mg)Ni2 is more resistant to crack formation and able to prevent the crack spreading. The weaker corrosion extent of La2MgNi9 in the electrochemical test is attributed to its better intrinsic anti-pulverization capability though the intrinsic anti-corrosion of La2MgNi9 is worse. Acknowledgments The authors are grateful to the Natural Science Foundation of China (NO. 51371094) and Natural Science Foundation Application of Inner Mongolia (NO.2014MS0526) for financial support. References [1]J Chen, N Kuriyama, H T Takeshita, H Tanaka, T Sakai, M Haruta. Hydrogen storage alloys with PuNi3-type structure as metal hydride electrodes. Electrochemical and Solid State Letters, 2000, 3: 249-252. [2]T Kohno, H Yoshida, F Kawashima, T Inaba, I Sakai, M Yamamoto, M Kanda. Hydrogen storage properties of new ternary system alloys: La2MgNi9, La5Mg2Ni23, La3MgNi14. Journal of Alloys and Compounds, 2000, 311: L5-L7. [3]S Yasuoka, Y Magari, T Murata, T Tadayoshi, J Ishida, H Nakamura, T Nohma, K Masaru. Development of high-capacity nickel-metal hydride batteries using superlattice hydrogen-absorbing alloys. Journal of Power Sources, 2006, 156: 662-666. [4]Y F Liu, Y H Cao, L Huang, M X Gao, H G Pan. Rare earth-Mg-Ni-based hydrogen storage alloys as negative electrode materials for Ni/MH batteries. Journal of Alloys and Compounds, 2011,509: 675-686. [5]J J Liu, S M Han, Y Li, L Zhang, Y M Zhao, S Q Yang, B Z Liu. Phase structure and electrochemical properties of La-Mg-Ni-based hydrogen storage alloys with superlattice structure. International Journal of Hydrogen Energy, 2016, 41: 20261-20275. [6]J Guo, D Huang, G X Li, S Y Ma, W L Wei. Effect of La/Mg on the hydrogen storage capacities and electrochemical performances of La-Mg-Ni alloys. Materials Science and Engineering B, 2006, 131: 169-172. [7]B Liao, Y Q Lei, G L Lu, L X Chen, H G Pan, Q D Wang. The electrochemical properties of LaxMg2-xNi9 (x=1.0-2.0) hydrogen storage alloys. Journal of Alloys and Compounds, 2003, 356-357: 746-749. [8]T Yang, T T Zhai, Z M Yuan, W G Bu, S Xu, Y H Zhang. Hydrogen storage properties of LaMgNi3.6M0.4 (M=Ni, Co, Mn, Cu, Al) alloys. Journal of Alloys and Compounds, 2014, 617: 29-33. [9]A Fà ©rey, F Cuevas, M Latroche, B Knosp, P Bernar. Elaboration and characterization of magnesium-substituted La5Ni19 hydride forming alloys as active materials for negative electrode in Ni-MH battery. Electrochimica Acta, 2009: 54: 1710-1714. [10]Z Y Liu, X L Yan, N Wang, Y J Chai, D L Hou. Cyclic stability and high rate discharge performance of (La,Mg)5Ni19 multiphase alloy[J]. International Journal of Hydrogen Energy, 2011, 36: 4370-4374. [11]T Sakai, K Oguro, H Miyamura, N Kuriyama, A Kato, H Ishikawa. Some factors affectin the cyble lives of LaNi5-based alloy electrodes of hydrogen batteries. Journal of Less-Common Metals, 1990, 161: 193-202. [12]D Chartouni, F Meli, A Zà ¼ttel, K Gross, L Schlapbach. The influence of cobalt on the electrochemical cycling stability of LaNi5-based hydride forming alloys. Journal of Alloys and Compounds, 1996, 241: 160-166. [13]B Liao, Y Q Lei, L X Chen, G L Lu, H G Pan, Q D Wang. Effect of the La/Mg ratio on the structure and electrochemical properties of LaxMg3à ¢Ã‹â€ Ã¢â‚¬â„¢xNi9 (x=1.6-2.2) hydrogen storage electrode alloys for nickel-metal hydride batteries. Journal of Power Sources, 2004, 129: 358-367. [14]Y F Liu, H G Pan, Y J Yue, X F Wu, N Chen, Y Q Lei. Cycling durability and degradation behavior of La-Mg-Ni-Co-type metal hydride electrodes. Journal of Alloys and Compounds, 2005, 395: 291-299. [15]X Z Sun, H G Pan, M X Gao, R Li, Y Lin, S Ma. Cycling stability of La-Mg-Ni-Co type hydride electrode with Al. Transaction of Nonferrous Metal Society of China, 2006, 16: 8-12. [16]P Zhang, Y N Liu, J W Zhu, X D Wei, G Yu. Effect of Al and W substitution for Ni on the microstructure and electrochemical properties of La1.3CaMg0.7Ni9-x(Al0.5W0.5)x hydrogen storage alloys. International Journal of Hydrogen Energy, 2007, 32: 2488-2493. [17]Y H Zhang, D L Zhao, B W Li, H P Ren, X P Dong, X L Wang. Cycle stability of La0.7Mg0.3Ni2.55-xCo0.45Cux(x=0-0.4) electrode alloys. Transaction of Nonferrous Metal Society of China, 2007, 17: 816-822. [18]Y M Li, H W Zhang, Y H Zhang, H P Ren. Changes of the crystal struc

Captain Ahab and Moby Dick Essay -- essays research papers

Captain Ahab and Moby Dick: Literary critics point to a variety of themes and juxtapositions when analyzing Herman Melville's â€Å"Moby Dick†. Some see the land opposed to the sea or Fate opposed to free will. Most mention man versus nature or good versus evil. A perspective that seems overlooked though is the perspective of the self and the other. The self and other is when one discovers the other (something not us) within oneself, when one realizes that one is not a single being alien to anything that is not them. There are many such relationships throughout the book, such as that of Ishmael and Queequeg and Ahab and Starbuck. However, this paper will focus on the essential relationship, which is of Ahab and Moby-Dick. By recognizing the other within ourselves, we are saved from hating the other in itself. Captain Ahab struggled to see Moby-Dick within himself, in this began the book's main problem of the self and the other. Before I get to this problem lets track the character of Ahab’s development up to that point. Chapters early in the book describe Ahab as having lost his leg to Moby-Dick. This character development suggests that Ahab is the victim of an attack by a vicious animal. However, by chapter 36 â€Å"The Quarter Deck", Ahab is described as a man infatuated with destroying a great white whale, named Moby-Dick. By chapter 37 â€Å"Sunset", it is obvious that Ahab is mad and in chapter 44 â€Å"The Chart", the reader is made aware of Ahab's "monomaniac thought of his soul." He was so obsessed with Moby-Dick that he couldn’t sleep. Ahab must have had some cause for his feelings toward the whale. It seems that Ahab and many other sailors have been exposed to the story of Jonah, which may have established man and whale as enemies. Also, is chapter 54 â€Å"The Town-Ho's Story" Melville tells of an account of Moby-Dick's capabilities. In this story, Moby-Dick snatches Radney from his ship and takes him below the ocean’s surface. However, for some reason Ahab does not hear this story. Melville may be showing the reader that the whale can be violent, and by not allowing Ahab to hear this story he (or the reader) won’t be able to use this information as an excuse for Ahab’s madness. By telling only the reader of the Town Ho's story, both the characters of Ahab and Moby-Dick are developed further. The character of the whale is set up as a dan... ...k this way Ahab created himself. Just like a master and slave relationship the self and the other are linked. There can be no slave without a master and there can be no master without a slave. When a master defeats and creates a slave, the master creates a role as "master" for himself or herself as well. In Melville's book, Ahab played the role of hunter and Moby-Dick became the hunted. The self/other relationship can be far more complicated than what has been offered here. Many racists, sexists and those who cannot tolerate homosexuality do not always follow the standards. Ahab and Moby-Dick are a special case of the relationship, and they are one that deserves consideration. Once again when I say self/other I am referring to a type of linkage of two separate beings. It is when one (the self) discovers the other (something not us) within oneself, when one realizes that one is not a single being alien to anything that is not them. The main point of this paper is the main problem of the self and the other which is that Captain Ahab struggled to see Moby-Dick within himself. Since he could not see this he hated and became obsessed with Moby Dick and thus apart of himself.

Personality and the Workplace :: Workplace Essays

Personality and the workplace 1 Individual Assignment on Personality and the Workplace PSY 250 – Psychology of Personality Personality and the workplace 2 There are many situations that can be mentioned when we get into the subject about interpersonal situations at my workplace, but on in particular pops out to my attention, respect. Respect is the one thing that the military was built up on. Well, during the next few pages you will read about how it has changed throughout the years in the military or at least in my career field, how it has been dealt with, how it got this way, what can be done to change it and who is responsible for making the changes. Not only will you read about respect, you will also read about how higher promotion rates have motivated many of the newer supervisors into trying to make the career field a better one for everyone. Through the use of creativity, involvement and implementation these new supervisors are trying to make a change in our military discipline that is so greatly needed. Since I have returned to my current career field, after managing three dorms, I noticed that the level of respect has changed from when I was there 2 and a half years prior. We have acquired many new very young troops who don’t want to do what they are told, not only are the younger troops acting this way, but many of the non commissioned officers (NCOs) or should I say lower ranking supervisors are acting this way as well. Things aren’t how they use to be when I first came into the military, back then you were told to do something and you did it no questions asked. It got done simply because someone who out ranked you told you to do it. Now days the troops want an explanation to why they are asked to do something, they don’t do it or they do it wrong or carelessly. Personality and the workplace 3 Due to the diversity of the personalities in our workplace it becomes very difficult to try and pin point a specific personality trait for the cause of our problems. It varies based on each individual; sometimes it is due to the fact that we as supervisors allow our subordinates to get away with murder. In the case of the military we strive on discipline and respect, and when we allow a troop to disrespect any of us or just let them cross over the line once, they forget that they are in the armed forces and tend to lower their standards.

Free Euthanasia and Doctor-Assisted Suicide Essay - Assisted Suicide :: Euthanasia Physician Assisted Suicide

Euthanasia The purpose of this essay is to inform readers clearly and coherently enoughof the terms and issues in the euthanasia debate that they can make sense of the euthanasia question. Descriptions are in relatively simple, non-technical language to facilitate learning. The definition of euthanasia is simple: "Easy, painless death." But the concept of euthanasia proposed by adherents of the euthanasia movement is complex and has profound consequences for all. Because the subject involves the discipline of medicine (diagnosis, treatment, prognosis, medical ethics and so on) as well as the discipline of law, the general public will have difficulty understanding it without some knowledge of these matters. We begin with the definition of terms: * Euthanasia: traditionally, an easy, painless death. Now used to mean "mercy killing," "assisted suicide," or "involuntary euthanasia." * Voluntary euthanasia: death administered to one who asks for it. In practice, truly voluntary euthanasia requests may be very rare, since the patient rarely gives informed consent because the alleged consent is influenced by depression, improperly treated pain or other factors that are not controlled but could be controlled. * Involuntary euthanasia: death administered without the recipient's consent, commonly known as "mercy killing," as in the case of children or incompetent adults. * Active, direct or positive euthanasia: direct killing of the patient by administering lethal drugs or other direct means of ending life, or by withholding or withdrawing ordinary means of sustaining life such as food and water, protection from exposure and so on. * Passive, indirect or negative euthanasia: ambiguous. Can be the decision by patient, parent or guardian and physician to withhold or withdraw extraordinary means of sustaining or prolonging life, such as deciding against high-risk surgery for a patient dying of cancer or kidney failure. When the intent is not to cause death but rather to reject extraordinary treatment, this results in the acceptance of death or continued life, whichever occurs, but it is not true euthanasia. The terms "passive," "indirect" or "negative euthanasia" should not be used since they play into the hands of euthanasia advocates by confusing legitimate actions with euthanasia, thereby desensitizing people to the fact that euthanasia is killing. More importantly, passive euthanasia is sometimes defined by others as the withholding of lifesaving treatment with the intention and result of causing the patient's death. This is the equivalent to active, direct euthanasia.

Unmistakably Racist

Miami is a state of America and so thus Michigan. These two states are both progressive like any other states in America. But when one tackles about the racism that is happening in those two states, there are some things that are surprisingly odd.After reading the article written by William Booth entitled â€Å"A White Migration North from Miami,† I easily got the gist of the article which says â€Å"There is a racism that is happening in Miami.† And from that very point of the fact that racism is present there, Michigan is no doubt a good comparison with that of Miami.On my own understanding of racism, I define it as a discrimination of a superior race over the inferior ones. In the article of Booth, he cited many instances wherein the Americans feel that they are being discriminated because of the fact that their population is clearly a minority in the state.It seems that wherever they go, even in malls, food chains or government institutions, the people are Spanish s peakers. They really feel that the place is not theirs anymore because of the massive invasion of the Spanish speaking people. To make the racism clear enough, I want to conclude from what Booth says in the article, that whoever holds the most population, they are the ones who are more likely rule the place just like what happened in Miami.It is true that there is a reverse racism in Miami. Americans usually think that they are the superior race. But in the case of Miami, Spanish speaking people become the superior class because of their increasing numbers. In Michigan, Americans still reign the seat of superior class.Tracing back the history, the White Americans were discriminating the Black Americans. One good example of it was the way the students were treated. According to Zbrozek of The Daily Michigan, blacks, unlike the whites, were not allowed to attend dance classes and to use swimming pools.He also said that blacks were also not enjoying the rights of white students to join political activities in school. The discrimination of whites towards the blacks is very evident.Nowadays, there was still some racism that is happening in Michigan but not that bad like before just like what   Monique Luse said because as what Isaac Curtis in the article written by Jeff Barr that a good man is no doubt a good man no matter what his color and race. And Black Americans have already proven their worth in the society.I think my point is now clear enough. Booth is right. The majority wins over the minority and in this case, it is not an exemption. Are you the one who is discriminating someone or the one who is being discriminated? If you are the racist one, have you ever wondered if discriminating people are good habit to do?What if you go to a place where you and your class are being discriminated because of the apparent fact that you are a minority group of people in that particular place? Do you think you will feel good? Come to think of it as early as now. You wil l never know what will be the twist of fate do unto you.Works CitedBooth, William. A White Migration North from Miami. The World is a Text.Sliverman , Jonathan. Rader, Dean. 9 November 1998. Washington Post Staff Writer.  Ã‚   28   June 2008.< http://www.fiu.edu/~fcf-whiteflight.html>Zbrozek, Chris. Confronting the racism in Michigan’s history. The Michigan Daily.11 April  Ã‚  Ã‚   2007.Barr, Jeff.   Society taught lessons of racism. Michigan News. 14 February 2008. Luse, Monique. Telephone Interview. 2 January 2002.