Trichomonas Vaginalis and HIV in Asymptomatic Pregnant Women

Trichomonas Vaginalis and HIV in Asymptomatic Pregnant Women PREVALENCE OF TRICHOMONAS VAGINALIS AND HIV CO-INFECTION AMONG ASYMPTOMATIC PREGNANT WOMEN IN ZARIA, NORTHERN NIGERIA ABSTRACT Background: Trichomonas vaginalis is the most common curable sexually transmitted infection worldwide. Serious adverse reproductive health outcomes including pregnancy complications, pelvic inflammatory disease, and an increased risk of HIV acquisition have been linked to Trichomonas vaginalis infection. Objective: To determine the prevalence of Trichomonas vaginalis in asymptomatic pregnant women and their HIV status in Ahmadu Bello University Teaching Hospital Zaria, Northern Nigeria. Methodology: A prospective cross-sectional descriptive study, using a proforma to obtain demographic and reproductive health information from consenting pregnant women attending antenatal clinic. Vaginal swab and blood samples was taken and analysed for Trichomonas vaginalis and HIV respectively. Data was analysed using SPSS V17 with p value of significance was set at 0.05. Results: The overall prevalence of Trichomonas vaginalis was 19.2%.There was an inverse relationship between the level of education and acquisition of Trichomonas vaginalis infection in pregnancy; women having no formal education had a higher prevalence of the Trichomonas vaginalis infection (7.5%) as against those who had tertiary education (1.7%). The 26- 30 years age group had the highest prevalence of both HIV infection (5.0%) and Trichomonas vaginalis infection (5.8%); strongly suggesting the possibility of co-infection between the two agents. There was a statistically significant association between Trichomonas vaginalis infection and HIV infection with a P value of 0.0003. The relative risk of acquiring HIV in the presence of Trichomonas vaginalis infection was 4. (RR 4.193 confidence Interval 1.756-10.01). Conclusion: Improvement of the socioeconomic status and education of women especially sexual health; will reduce the prevalence of Trichomonas vaginalis and HIV co-infection. Keywords: Pregnancy, Trichomonas vaginalis, HIV infection INTRODUCTION Trichomonas vaginalis has continued to cause serious adverse reproductive health outcomes including pregnancy complications, pelvic inflammatory disease, and an increased risk of HIV acquisition1 The magnitude of social and economic consequences of sexually transmitted infections (STIs) in developing countries has made it a major public health problem. 2, 3 STIs are also found in pregnant women and the prevalence is higher in Africa causing significant maternal and perinatal morbidity. 3-5 Trichomonas vaginalis is a unicellular flagellate protozoan organisms that cause STI.6 Many STIs including those due to Trichomonas, can be transmitted to the fetus via transplacental spread or by passage through the birth canal and via lactation to the neonate. 6 Sexually Transmitted Infections (STIs) and other Reproductive Tract Infections (RTIs) have been associated with a number of adverse pregnancy outcomes which includes abortion, stillbirth, preterm delivery, low birth weight, postpartum sepsis, neonatal pneumonia, neonatal blindness congenital infection. 2-5, 7 Recent research has shown that having one untreated STI increases the risk of contracting another potentially more dangerous one, like Human Immunodeficiency Virus (HIV) infection if there is exposure. 8, 9Trichomoniasis in pregnancy has been reported to impacts adversely on birth outcomes and is also a co-factor in Human Immunodeficiency Virus (HIV) transmission and acquisition. 10, 11 Clinical infection with Trichomonas vaginalis in the neonate is an unusual occurrence and has been reported in a two weeks old girl child presenting with vaginal discharge with complete resolution to metronidazole treatment.12 Due to high frequency of the infection during pregnancy and the development of metronidazole-resistant isolates, therapeutic alternatives to 5-nitroimidazole are being searched like Triterpenes; which are natural products presenting several biological activities such as anti-protozoal activity.13 The prevalence of Trichomonas vaginalis infections are typically underestimated due to poor sensitivity of diagnostic tests.6 However, the World Health Organization (WHO) quoted the overall prevalence as 3.1%.6, 14 In Nigeria the prevalence observed in an Enugu study was 6.9%; 15 4.7% was seen in Ilorin16 and 29.8% in Lagos.17 In the sub-Saharan Africa, including Nigeria, Trichomoniasis has neither been the focus of intensive study nor of active control programs, and this neglect is likely a function of the relatively mild nature of the disease. 18 This study explored the rate of Trichomonas infection in pregnancy as well as the level of co-infection with HIV with a view to adding to the growing body of literature and suggests control measures. METHODOLOGY This was a cross sectional study which was conducted over a three month period. Questionnaires were used to obtain the socio-demographic and reproductive profile from consenting clients who were attending antenatal clinic for the first time in their current pregnancy at the Ahmadu Bello University Teaching Hospital, Zaria, Northern Nigeria. High vaginal swabs and blood specimens for both Trichomonas vaginalis and HIV were obtained and analysed. The data obtained was analyzed using Statistical Package for Social Science (SPSS) Version 17.0 for windows. The level of significance was considered to be p-value Trichomonas vaginalis and HIV infection was determined using the Epi-Info software. RESULTS A total of 120 women consented for the study. The socio-demographic and obstetric characteristics of the patients are as shown in Table 1.0. The mean age was 28.5 + 2.3years, mean gravidity was 3.5 and 20 weeks was the average gestational age at booking. The overall prevalence of Trichomonas vaginalis was 19.2%. The 26-30 years age groups having a value of 5.8% which was closely followed by age group 21-25years with 5.0%. The lowest prevalence was found at age group 36-40years. Low level of education is shown to have a positive impact on the acquisition of vaginal Trichomonas vaginalis. Clients having low level of education had a higher prevalence of the Trichomonas vaginalis; 7.5% was seen in those with Koranic (non-formal) education. The prevalence was however lowest in those who had tertiary education 1.7%.- The highest prevalence was seen in clients who were housewives (10.5%); students and civil servants had the lowest prevalence of 1.7% and 2.5% respectively. Mutigravidae are more likely than primigravidae to have Trichomonas vaginalis infection (15.0% vs. 4.1%). The prevalence was observed to be highest in the second trimester (10.8%) as compared to the first and third trimester which were 5.0% and 3.3% respectively. The frequency distribution of HIV status in the study population among the consenting client is shown in Table 2.0. Sixteen out of 98 were positive for HIV giving a prevalence of 16.3%. Figure 1.0 shows the percentage distribution of HIV by client’s age group. It was observed that HIV was more prevalent in age group 26-30years (5.0%) and was least prevalent in the older age group of 36-40years (0.8%). The relationship between the occurrence of Trichomonas vaginalis and HIV infection is shown in a two by two table (Table 2.0). DISCUSSION The prevalence of Trichomonas vaginalis found in this study was 19.2%. The World Health Organization quoted a prevalence of between 3.0- 3.1%6, 14, 19, but added that there was under reporting of the infection. Prevalence rates as high as 29.8% was found in Lagos, Nigeria 17 16.0% was seen in Mwanza, Tanzania20 and a lower rate of 4.7% and 6.9% were found in Ilorin, Nigeria 16 and Enugu, Nigeria15 respectively. A prevalence of 3.7% was seen in a study in Togo.21 Our result compares with that of Tanzania. In the age related prevalence, the study showed a steady increase in prevalence between ages of 16 to 30years, with the highest rate of 5.8% occurring in the age group 26-30years. This may suggest an increasing sexual activities along the age line considering the fact that Trichomonas vaginalis is sexually transmitted. This can also probably explain the decline in prevalence in the older age group with lowest rate of 0.8% at age group 35-40years. There is however a slight variation with the Enugu study which found the highest age related prevalence of 3.7% among the age group 20-25years. There was an inverse relationship between the level of education and acquisition of Trichomonas vaginalis infection in pregnancy; women having no formal education had a higher prevalence of the Trichomonas vaginalis infection (7.5%) as against those who had tertiary education (1.7%). This was consistent with findings in Enugu and Ilorin where low level of education was associated with Trichomonas vaginalis infection. Formal education is associated with improvement in personal hygiene and sexual behavior. The prevalence of Trichomonas vaginalis was highest among housewives and least among students; this was unlike the Enugu study that found the highest prevalence to be among the business group. The sociocultural backgrounds of the two environment relatively differs and the lack formal education among housewives in our environment can be a predisposing factor to the acquisition of Trichomonas vaginalis infection. There appears to be a relationship between parity, trimester of pregnancy and infection with Trichomonas vaginalis. Previous pregnancies was recorded in the literature to be a risk factor.10 This study showed a higher prevalence rate among the multigravidae as compared to primigravidae. The prevalence was highest in the second trimester of pregnancy as compared to other trimesters. This findings was similar that of Cotch et al4 in their study of vaginal infections and prematurity; where Trichomonas vaginalis infection was commonest in mid gestation. The mean age at booking was 20 weeks showing that most women were seen in the second trimester when Trichomonas vaginalis infection was more likely to be present. The prevalence of HIV infection in this study was 16.8% which was higher than the national average of 3.4% and Kaduna state average of 9.2%. 22 This may be explained by the fact that most of the clients were in their reproductive years and the Ahmadu Bello University Teaching Hospital, Zaria was a major referral center for the Prevention of Mother To Child Transmission (PMTCT) of HIV in Northern Nigeria. Both HIV and Trichomonas vaginalis infection were highest in the age group 26-30 years; this was strongly suggestive of the possibility of co-infection between the two agents. There was a statistically significant association between Trichomonas vaginalis infection and HIV infection with a P value of 0.0003. There was a four times relative risk of acquiring HIV in the presence of Trichomonas vaginalis infection (RR 4.193 confidence Interval 1.756-10.01). CONCLUSION AND RECOMMENDATIONS Routine screening for STIs like Trichomonas vaginalis during antenatal period should be the standard of care because of its proven benefits on the outcome of pregnancy. Metronidazole which is the treatment option when found, is a cheap, readily available and safe in pregnancy. Additionally, screening for HIV co-infection will add value to healthcare services in the antenatal clinic. Improvement of the socioeconomic status and formal education in women especially sexual health and lifestyle modification is likely to reduce the prevalence of Trichomonas vaginalis and HIV co infection. REFERENCE: Coleman JS, Gaydos CA, Witter F. Trichomonas vaginalis Vaginitis in Obstetrics and Gynecology Practice: New Concepts and Controversies. Obstet Gynecol Surv. Jan 2013; 68(1): 43–50. doi: 10.1097/OGX.0b013e318279fb7d Begum A, Nilufar S, Akther K, Rahman A, Khatun F, Rahman M. Prevalence of selected reproductive tract infections among pregnant women attending an urban maternal and childcare unit in Dhaka, Bangladesh. J Health Popul Nutr 2003; 21: 112-6. Muelen J, Mgaya HN, Chang-Claude J, et al. Risk factors for HIV infection in gynaecological inpatients in Dar Es Salaam, Tanzania, 1988-1990. East Afr Med J 1992; 69: 688-92. Cotch MF, Pastorek JG, Nugent RP: Trichomonas vaginalis associated with low birth weight and preterm delivery.The Vaginal Infections and Prematurity Study Group. Sex Transm Dis 1997 Jul; 24(6): 353-60 Shuter J, Bell D, Graham D, Holbrook KA, Bellin EY. Rates of and risk factors for trichomoniasis among pregnant inmates in New York City. Sex Transm Dis 1998; 25: 303-7. Richard Gentry Wilkerson, et al. Trichomoniasis via http/eMedicine emergency medicine>infectious disease. Accessed March 20 2008, 1430hrs. Sebitloane HM, Moodley J, Esterhuizen TM. Pathogenic lower genital tract organisms in HIV-infected and uninfected women, and their association with postpartum infectious morbidity. S Afr Med J. 2011 Jun 27; 101(7):466-9. Ament, L. A. and E. Whalen (1996). â€Å"Sexually transmitted diseases in pregnancy: diagnosis, impact, and intervention.† J Obstet Gynecol Neonatal Nurs 25(8): 657-66. Borchardt, K. A. (1994). â€Å"Trichomoniasis: its clinical significance and diagnostic challenges.† Am Clin Lab 13(9): 20-1. Laga M, Manoka A, Kivuvu M, et al. Non- ulcerative sexually transmitted diseases as risk factors for HIV-1 transmission in women: results from a cohort study. AIDS 1993; 7: 95-102. Sorvillo F, Smith L., Kerndt P, et al. Trichomonas vaginalis, HIV and African-Americans. Emerg Infect Dis 2001; 7:927-32 (Medline). Irving S D, James M S et al; Neonatal T. Vaginalis infection. Journal of Emergency Medicine; vol 13 issue 1 Jan – Feb 1995. 51-54 Innocente AM, Vieira PB, Frasson AP, Casanova BB, Gosmann G, Gnoatto SC, Tasca T. Anti-Trichomonas vaginalis activity from triterpenoid derivatives. Parasitol Res. 2014 Aug; 113(8):2933-40. doi: 10.1007/s00436-014-3955-0. Madeline S et al Trichomoniasis highly prevalent in US black women clin infec dis 2007; 45:1319-1325 Chigozie J. U, Cletus D. C. U., Ali, Mirian A. Trichomonas vaginalis infection in pregnant women in South – Eastern Nigeria; a public health importance. The internet Journal of obstetrics and gynecology accessed 20th April 2008. Aboyeji AP, Nwabuisi C. Prevalence of sexually transmitted diseases among pregnant women in Ilorin, Nigeria. J Obstet Gynaecol 2003; 23: 637-9. Oladele TO et al, Reliance on microscopy in T. Vaginalis Diagnosis and prevalence in female presenting with vaginal discharge in Lagos Nigeria.eMedicine on pubmed accessed 20 August 2008 2100Hrs Ogunjobi BO, Osola AO; Trichomonal Vagintis in Nigerian Women; Tropical Geographic Medicine 1984 36(1): 67-70. WHO: Trichomoniasis. Available at: http://www.who.int. Mayaud P, Uledi E, Cornelissen J, et al. Risk scores to detect cervical infections in urban antenatal clinic attenders in Mwanza, Tanzania. Sex Transm Infect 1998; 74 Suppl 1: S139-46. Tchelougou DI, Karou DS, Kpotsra A, Balaka A, Assih M, Bamoke M, Katawa G, Anani K, Simpore J, de Souza C. Vaginal infections in pregnant women at the Regional Hospital of Sokode (Togo) in 2010 and 2011. Med Sante Trop. 2013 Jan-Mar;23 (1):49-54. doi: 10.1684/mst.2013.0142. Federal Ministry of Health [Nigeria] (2013). National HIV AIDS and Reproductive Health Survey, 2012 (NARHS Plus). Federal Ministry of Health Abuja, Nigeria. Pp 40-42. 1

Nickel Base Super Alloys For Aerospace Materials Engineering Essay

A ace metal, high public presentation metal is an metal which exhibits first-class mechanical strength and weirdo opposition and besides have good corrosion and oxidization opposition. Super metal typical have a matrix with face centered three-dimensional crystal construction. A Ace metal base debasing component is nickel, Co, or nickel-iron. In Earlier 1950 ‘s unstained steel is used as a ace metal. Super metal growing that has quickly improved both on chemical and processing of that which led to rapid growing in aerospace, industrial gas turbine and marine turbine industry. In which nickel base ace metal are used in the readying of the turbine blades which can defy long clip at the elevated temperatures for the betterment of the public presentation of the turbine. Desirable features of high temperature ace metals: 1. Nickel basal metal should hold ability to defy lading at an operating temperatures near to the thaw point. 2. It has significant opposition to mechanical debasement over the drawn-out period of clip ( immune to crawl ) . 3. It should digest terrible runing environments ( immune to corrosive atmosphere ) .Chemical composing and Microstructure of Nickel base super alloys.Earlier Ni-based ace metal was derived from metals incorporating add-ons of chromium, copper, carbon monoxide and fe.With belongingss superior to that of chromium steel steels as these individual stage Ni-base metal exhibits good high temperature strength and corrosion opposition. As rigorous demands of the quickly developing aerospace industry. To better the above desirable features of the ace alloys aluminium add-ons to be added to individual stage nickel base super alloys to bring forth two stage microstructure to organize ordered ?1 matrix distributed within a broken ? matrix. In the stage diagram as the Al degrees typically at about 18 atomic % and staying 70-80 % as Ni. As the big emphasiss are required for the disruption of the ?1precipitates to boot shearing of the precipitates the ordination of the ?1 precipitates requires the formation of the anti stage boundary. As the big emphasis required for orowan obeisance and the shearing of the precipitates. So, these cubelike crystals of the secondary stage are highly effectual in suppressing the mobility of the disruptions. And besides improves the weirdo belongingss at the temperatures from 700-10000c.As the high temperature belongingss of Ni-base super metals are: Ni has a face centered three-dimensional crystal construction with high thaw temperature which makes it malleable and tough.Ni is stable in Fcc crystal construction from room temperature to its runing point. so there is no stage alteration and diffusion rates in Ni are low which improves microstructure stableness at elevated temperatures. As the misfit between the ? and ?1 precipitates will alter the microstructure under the influence of th e emphasis as this is controlled by changing the chemical composings and treating conditions. As in the Ni base ? – ?1 precipitates the strength and weirdo opposition has been increased by developing some technology solutions to get the better of the restrictions. The major debasing elements that should be added to Ni base metals are Al, Ni, Ti and Nb as the add-on of these tend to divider of preferentially to intermetallic ?1 precipitates. Co add-on provides solid solution beef uping but is chiefly added to modify the ?1 solvus temperatures. And other debasing add-ons are Re, W, Mo, V, Cr and Pt group metals are added to beef up to both solid ? and ?1 precipitates at elevated temperatures. As the Al and Cr both are added to beef up the Ni-base metals but depending upon the belongingss required should be added for one peculiar set of belongingss. The minor debasing elements such as B, C, Zr and Hf, were added ensuing in the formation of the carbides and on occasion borides at the grain boundary. As the C atoms exhibit high affinity for the elements such as Hf, Zr, Ta and Ti, Nb, tungsten, Mo, V and Cr, the bulk of carbides in Ni-base metal is metal atom carbides may precipitate from liquid during hardening. As the carbides may impact the weariness belongingss of the stuff the presence of the distinct carbide at the grain boundary inhibits the sliding and harm during the weirdo.Creep behavior of Ni-based metals:Creep is the distortion under the influence of emphasiss at elevated temperature. Creep is the clip dependent, inelastic and irrerecoverable distortion. Creep is more terrible in stuffs subjected to heat for a long periods. As creep ever increases with temperature. The rate of distortion of the stuff depends upon the stuff belongingss, clip, temperature and applied emphasis. See the blades of the turbines as the weirdo of the blade is to reach the shell, ensuing in the failure of the blade. Creep does non happen all of a sudden like brickle stuffs as it is a clip dependent distortion. The phases of the weirdo are in the primary phase strain rate is comparatively high, but slows with increasing strain this is due to work hardening, in the secondary phase the strain rate finally reaches minimal and becomes changeless and in the concluding phase strain additions quickly because of the necking phenomena. General creep equations: d?/dt = C?m/db e-q/kt Where ? is the weirdo strain, C is changeless dependant on the stuff, ? is the applied emphasis, m and B are the advocates depend on weirdo is the grain size, K is Boltzmann ‘s invariable. There are 3 types of weirdo:Dislocation weirdo:Dislocation weirdo of the stuff is the motion of the disruptions through the crystal lattice. It causes fictile distortion of the single crystals at the terminal of the stuff. d?/dt = A?ne-q/ktNabarro-herring weirdo:Nabarro-herring weirdo is a signifier of diffusion weirdo in which atoms migrate within the grain boundary to stretch grain along the emphasis axis. At higher temperatures the diffusivity additions due to the direct temperature dependance of the equation, the addition in the vacancy through defect formation, an addition in the mean energy of the atoms in the stuff.Coble weirdo:Coble weirdo is besides one of the diffusion controlled weirdo as the atoms diffuse along the grain boundary which produces a net flow of the stuff and a sliding of the grain boundaries.Defects in crystals:a – interstitial dross atom in the crystal lattice b – Edge disruption in the crystal c – Self interstitial atom of the stuff d – Vacancy in the lattice construction e – Precipitate of dross atoms f – Vacancy disruption of the cringle g – Interstitial disruption in the cringle h – Substitution dross atom in the stuffDislocations:Dislocation is a 1-D defect as the lattice is merely disturbed along the disruption line. The disruption of the crystal may be generated due to some vacancies, point defects, interstitial drosss in the crystal lattice.Edge Dislocation:The motion of the disruption moves the crystal from one side relation to the other. In the figure below the left figure shows the shutting of the disruption crystal. And the right figure shows same concatenation of base vectors in a perfect mention lattice and the circuit does non shut the vector which closes the circuit is called Burgers vector which represents the disruption of the crystal.Screw disruption:The atomic representation of the screw disruption is complicated and still Burgers vector is possible to stand for the disruption. If we move on the circuit of the disruption it will travel in a handbill like a prison guard. So, this is called as prison guard disruption as the Burgers vector does non alterations in both the disruptions but there is a alteration in the mark convention depending upon the clockwise and anti clock rotary motion of the vectors along the circuit.Defects in the gamma premier stage:The defects in the gamma premier stage undergo 3 types of defects they are 1. Planar defects 2. Line defects 3. Point defects As the defects the Ni and Al atoms, when bonded together an interface boundary known as the anti-phase boundary offprints Ni-Ni and Al-Al bonds as the figure of Ni-Al bonds near the APB is well reduced. In the line defects the stage dissociate into partial disruptions. In the point defects as the compositional scope of Al is 23 to 27 % .Thus, merely little divergences causes the point defects.Strengthening in nickel base metals:The mechanical belongingss of the Ni based alloys depend on the province of microstructure, chemical composing and processing conditions. As the disruptions of the stuff is reduced by some beef uping mechanisms to increase the hardness and strength. Work hardening: Solid solution strengthening/alloying: In this mechanism the solute atoms of one component are added to another, ensuing in either significant or interstitial point defects. The solute atoms cause lattice deformations that impede disruption gesture. The emphasis required to travel disruptions in the stuff is: ? = Gbc1/2?3/2 Where degree Celsius is the solute concentration and ? is the strain on the stuff caused by solutePrecipitation Hardening:In most metals, 2nd stage can be precipitated from matrix in solid province. The atoms that compose the 2nd stage precipitates act as traping points in a similar mode to solutes. The disruptions in a stuff can interact with the precipitate atoms in one of two ways. If the precipitate atoms are little, the disruptions would cut through them. If larger precipitate atoms, looping or obeisance of the disruptions would happen. For atom looping/bowing ? = Gb/L-2r For atom film editing ? = r/bLGrain boundary strengthening:In metals grain size has enormous influence on the mechanical belongingss. Because grains normally have changing crystallographic orientations, grain boundary arises. The emphasis required to travel a disruption from one grain to another in order to plastically deform a stuff depends on the grain size. The mean figure of disruptions per grain lessenings with mean grain size.Processing of individual crystal Nickel based metals:Hardening theory:Equations for growing:Hardening is a physical alteration from liquid province to solid province of the stuff. As the heat transportation from the system to the milieus. In general, the composing of solid should be different from that of the liquid with an impure stuff will besides necessitate conveyance of solute. The regulating equations for the diffusion of heat and solute is I = S for solid and L for liquid, Ci =solute concentration in stage I, Ti = temperature in stage I, Di= solute diffusion coefficient in stage I, ? = Thermal diffusion coefficient, At the interface between solid and liquid Ts1 = TL1 = TI TI = Temperature of solid/liquid interface. CsI = kCL1 K = distribution coefficientSolute under chilling:This is the equation under chilling due to the presence of the solute in the stuff. The composing of the liquid at the interface, CL1 will in general will be different from the majority composing. If the stuff is pure ( ?Ts = 0 )Curvature under chilling, ?T?T? = ?â€Å" ( 1/R1+1/R2 ) â€Å" = Gibbs Thomson coefficient. R1, R2 = rule radii of curvature As the Gibbs Thomson consequence arise due to the extra energy associated with the formation of a solid/liquid interface.Kinetic under chilling ?Tk:Growth of stage is a non equilibrium procedure during the procedure atoms gain energy between liquid and solid and a net transportation of atom will merely happen. As the drive force through the under chilling is known as kinetic under chilling.Interface construction:The interface construction is dependent on the solid/liquid interface bonding. The growing of the interface may be of two types.1. Faceted growing:In faceted growing the crystals are bonded by angular surfaces turning to crystallographic plane. As the substances exhibit complex crystal construction and way bonding.2. Non-Faceted growing:There is similarity between constructions, denseness and bonding in the solid and liquid interface. The dynamicss is independent of crystal orientation and the interface between the two stages will be more gradual and it becomes automatically unsmooth.Hardening of pure stuffs:For pure stuffs the above solute equations are non important. As in the under chilling for the pure stuffs ?Ts = 0.There stableness of the solid/liquid interface for pure stuffs will be dependent on the conditions of growing. There are two methods1. Columnar ( or ) directional hardening:In the directional hardening heat is extracted through the solid in the opposite way to the growing way.2. Equiaxed hardening:The heat extracted through the under cooled liquid into which the free crystals are turning. As the disturbance in the hardening forms spherical interface. Heat rejected is more the spherical interface will ever be unstable.Hardening of Binary metals:Directional hardening of binary metals for two-dimensional interface:The growing produced by easy traveling liquid specimen from a furnace. It is known as directional hardening. For two-dimensional interface, ?Tr =0 and the equilibrium at the interface ?Tk =0.Therfore the under chilling and compos ings at the interface will be given equilibrium. For the hardening of the metal three instances are to be considered. A Typical stage diagram of a two component metal.1. Complete commixture in liquid, none in solid:This is practically merely possible when either the specimen length is really little or if a convective commixture in the liquid. The solute rejected by each little volume of the solid to organize distributed equally throughout the staying liquid.2. No convection diffusion in liquid, none in solid:This state of affairs occurs in thin specimen, gravitation stabilised or infinite experiment. Hardening begins with an initial transient during which an enriched solute boundary bed builds up in front of the solid/liquid interface.3. Partial commixture by convection in liquid:In this method presume a dead boundary bed of width in front of the solid/liquid interface in which conveyance occurs by diffusion merely. Outside this bed there is a complete commixture in the liquid.Columnar and Equiaxed grain construction:Equiaxed grain construction: The heat is extracted through the under chilling liqui d. The temperature at the tip of the dendrite is negative. This is besides known as stray growing or unconstrained growing. The commanding parametric quantity for the growing speed is merely the under chilling Columnar grain construction: The heat is extracted through the solid in the opposite way to the growing way. The temperature at the tip of the dendrites is positive. It has constrained growing because the speed is fixed.Investing casting for individual crystal turbine blades:Investing casting is besides known as low wax casting. This procedure is one of the oldest fabrication procedures. It can be used to do the parts that can non be produced by normal fabricating technique such as turbine blades and high temperature aerospace stuffs. The cast is made up of form utilizing wax or some other stuff that can be melted off. This wax form is dipped in the furnace lining slurry, which coats the wax. This is dried and the procedure of dunking in the slurry and drying is repeated until a robust thickness is achieved. After the full form is placed in the oven and the wax is melted off. The stuff used for the slurry dwelling of binder and a mixture of aluminum oxide, ziricon and silicon oxide followed by stuccoing. The mold therefore produced can be used straight for the light casting. A conventional diagram of investing casting procedure Grain boundary picker:Growth of individual crystal metal utilizing grain picker:The blades of individual grain construction is achieved by directional hardening combined with a coiling grain picker with cylindrical base seed as in projecting metalworkss, the block is placed at the underside of the mold. The mold is withdrawn from the furnace to turn the blade. Several grains nucleated with the starter block can turn into a coiling transition manner and most of them will be eliminated and merely one grain survives during the growing. If the hardening in the organic structure starts from a individual crystal. As the grain orientation optimisation and a coiling grain picker easing dendrite ramification to guarantee that merely individual grain finally survives at the top of the seedDirectional hardening in investing casting:In the directional hardening to turn columnar grains the heat should be extracted through the solid, in the opposite way to the growing way. For Ni-base metals, the most rapid dendrite growing way is selected as the long axis for the blades.

Bluebells of Scotland

Bluebells of Scotland â€Å"Bluebells of Scotland† is a piece written and composed in the late romantic era around 1899 by Arthur Pryor. The piece was composed from a traditional Scottish folk song for the trombone and orchestral accompaniment. In the late 1800s the trombone was not viewed as an instrument that could perform particularly difficult pieces. Compelled by society’s negative opinion of the trombone, Pryor composed â€Å"Bluebells of Scotland† in order to display the capabilities of the trombone and to emphasize that it could play very difficult pieces.This piece is a little more upbeat and physical than other pieces of the same time period, but what makes this piece particularly unique is that it is the only piece with a high level of difficulty for trombone that was composed in the time of its conception. The piece is intended to be accompanied by an orchestra but can be played with piano accompaniment as well. The characteristics of this piece are v ery dynamic and free. The expressivity of the piece is left up to the interpretation of the performer which allows for a large amount of freedom and creativity.There are quite a few cadences that allow the performer to take control of tempo and dynamics. â€Å"Bluebells of Scotland† includes both very slow and lyrical passages as well as many very quick and difficult runs, double-tonguing, octave jumps, lips slurs, and a vast amount of high register notes. The introduction of the piece begins with a triumphant cadence peaking at a high register C, which slowly decays into a very lyrical melodic sequence that takes the shape of the original lyrics, which read: â€Å"Oh where, tell me where, is your highland laddie gone?Oh where, tell me where, is your highland laddie gone? He's gone with streaming banners where noble deeds are done. And it's oh! in my heart I wish him safe at home. † The piece then moves into a much more difficult technical variation of the original mel ody and progressively builds in speed until the also very triumphant ending. Around the time the then eighteen or nineteen year old Arthur Pryor composed â€Å"Blue Bells of Scotland†, he had only been playing the slide trombone for three to four years.Pryor was given the slide trombone as a payment to a debt and taught himself to play it fairly quickly. Amazingly, Pryor wrote the piece with the knowledge of only a few slide positions and would use false tones and alternate positions for notes in the fifth, sixth, and seventh positions. Despite this, â€Å"Blue Bells of Scotland† is still one of Pryor’s most memorable pieces and is still widely known today. A few years after composing â€Å"Bluebells of Scotland† he arrived in New York by invitation of John Philip Sousa.After arriving to be in Sousa’s new concert band, Pryor was offered by Frank Holton the position of principle chair trombonist. When Holton left the position, Pryor became the featu red soloist of over 10,000 solos as principle trombonist for Sousa’s band. â€Å"Blue Bells of Scotland† serves as a constant reminder of the trombone’s capabilities as a very lyrical instrument and its ability for technical prowess as well. Arthur Pryor inspired interest in the trombone with his virtuoso playing, and â€Å"Bluebells of Scotland† in particular has been a standard of trombone literature for decades and a favorite challenge for advanced players†(Kleiner). The piece will always have a special place in the hearts of all trombonists, both past and future. Works Cited http://www. celticscores. com/sheet-music/628_Blue_Bells_of_Scotland http://bluebellstrilogy. com/blog/2010/05/arthur-pryor-blue-bells-and-trombone/

Reasons to Be Pretty, a Play by Neil LaBute

Reasons to Be Pretty is a hard-edged comedy written by Neil LaBute. It is the third and final installment of a trilogy (The Shape of Things, Fat Pig, and Reasons to Be Pretty). The trio of plays are connected not by characters or plot but by the recurring theme of body image within American society. Reasons to Be Pretty premiered on Broadway in 2008. It was nominated for three Tony Awards (Best Play, Best Leading Actress, and Best Leading Actor). Meet the Characters Steph is the central argument of the play. Throughout the story, she is furious. She feels emotionally wounded by her boyfriend—who believes that her face is regular (which she views as a way of saying that she is not beautiful). Greg, the protagonist, spends most of his life trying to explain his misunderstood intentions to others. Like other leading men in Neil LaBute plays, he is far more affable than the male supporting characters (who are always foul-mouthed jerks). In spite of his low-key, eager-to-remain-calm personality, Greg somehow evokes anger from the rest of the characters. Kent is the obnoxious jerk character we were just talking about. He is crude, down-to-earth, and believes that his life is better than perfect. He not only has a good-looking wife, but hes also tangled in a work-related affair. Carly is the wife of Kent and the best friend of Stephanie. She sets the conflict in motion, spreading gossip about Gregs supposedly true feelings. Reasons to Be Pretty Plot Summary of Act One Scene One In Scene One, Steph is very angry because her boyfriend Greg supposedly said something derogatory about her physical appearance. After a heated argument, Greg explains he and his friend Kent had a conversation in Kents garage. Kent had mentioned that the newly hired woman at their workplace was hot. According to Greg, he replied: Maybe Steph hasnt got a face like that girls. Maybe Stephs face is just regular. But I wouldnt trade her for a million bucks. After his admission, Steph storms out of the room. Scene Two Greg hangs out with Kent, recounting his fight with Stephanie. During their conversation, Kent chastises him about eating an energy bar directly after a meal, claiming that Greg will get fat. Kent goes into the bathroom. Kents wife Carly arrives. Carly is in law enforcement. She is the one who gossiped to Steph about Gregs conversation, regarding her regular face. Carly harshly criticizes Greg, detailing how upset Steph has become, reacting to his insensitive words. Greg argues that he was trying to say something complimentary about Steph. Carly states that his communication skills suck. When Kent finally returns from the bathroom, he defuses the argument, kisses Carly, and advises Greg to treat women nicely to keep the relationship happy. Ironically, whenever Carly is not around, Kent is far more demeaning and derogatory than Greg. Scene Three Steph meets Greg in neutral territory: a restaurant at lunchtime. He has brought her flowers, but she remains intent on moving out and ending their four-year relationship. She wants to be with someone who sees her as beautiful. After unleashing more of her anger and rebuking Gregs attempts at reconciliation, Steph demands the keys so she can remove all of her items from their home. Greg finally fights back (verbally) and says that he doesnt want to see her stupid face anymore. That makes Stephanie snap! Steph makes him sit back down at the table. She then pulls out a letter from her purse. She has written down everything about Greg that she dislikes. Her letter is a vicious (yet amusing) tirade, detailing all of his physical and sexual flaws, from head to toe. After reading the hateful letter, she admits that she wrote all of those things to hurt him. However, she says that his comment about her face represents his true beliefs, and can therefore never be forgotten or taken back. Scene Four Kent and Carly sit together, complaining about work and money. Carly criticizes her husbands lack of maturity. Just as they start to makeup, Greg arrives to hang out and read a book. Carly leaves, annoyed because she blames Greg for making Steph move away. Kent reluctantly confides in Greg, admitting that he is having an affair with the hot girl at work. He goes through a long list of positive details about her physique. (In many ways it is the opposite of Stephs angry letter monologue.) At the end of the scene, Kent makes Greg promise not to reveal the affair to anyone (especially Steph or Carly). Kent claims that men must stick together because they are like buffalo. Act One of Reasons to Be Pretty concludes with Gregs realization that his relationship is not the only one that has fallen apart.