What Happened to Shakespeares Skull

What Happened to Shakespeares Skull An examination of William Shakespeare’s  grave  in March 2016 suggested that the body is missing its head and that Shakespeare’s skull may have been removed by trophy hunters some 200 years ago. However, this is just one interpretation of the evidence found in this excavation. What really happened to Shakespeares skull is still up for debate, but we do now have some important evidence concerning the famous playwrights grave. Shakespeare’s Grave For four centuries, William Shakespeare’s  grave sat undisturbed underneath the chancel floor of Holy Trinity Church in Stratford-upon-Avon. But a new investigation conducted in 2016, the 400th anniversary of Shakespeare’s death, has finally revealed what lies beneath. The church has never allowed an excavation of the grave- despite many appeals from researchers over the centuries- because they wanted to abide by Shakespeare’s wishes. His wishes were made crystal clear in the inscription carved into the ledger stone above his grave: Good friend, for Jesus sake forebeare, To digg the dust enclosed heare; Bleste be the man that spares thes stones, And curst be he that moves my bones. But the curse is not the only unusual thing about Shakespeare’s grave. Two more curious facts have bothered researches for hundreds of years: No name:  Of the family members buried side by side, William Shakespeare’s ledger stone is the only one that doesn’t carry a name.Short grave:  The stone itself is too short for a grave. At less than a meter in length, William’s ledger stone is shorter than the others, including that of his wife, Anne Hathaway. What Lies Beneath Shakespeare’s Tombstone? The year 2016 saw the first archaeological investigation of Shakespeare’s grave using GPR scanning to produce images of what lies beneath the ledger stones without the need to disturb the grave itself. The results have disproved some firmly held beliefs about Shakespeare’s burial. These break down into four areas: Shallow graves: It has long been asserted that the Shakespeare ledger stones covered a family tomb or vault beneath. No such structure exists. Rather there is nothing more than a series of five shallow graves, each aligned with the corresponding ledger stone in the chancel floor of the church.No coffin: Shakespeare was not buried in a coffin. Rather, the family members were buried simply in winding sheets or a similar material.Disruption at the head: Shakespeare’s mysteriously short ledger stone corresponds to a repair that has been made underneath the stone floor to support it. Experts suggest that this is due to disturbance at the head end of the grave which has caused significantly more subsidence  than elsewhere.Interference:  The tests conclusively proved that Shakespeare’s grave is not in its original state. Stealing Shakespeares Skull The findings correspond to a rather incredulous tale first published in an 1879 edition of the Argosy Magazine. In the story, Frank Chambers agrees to steal Shakespeare’s skull for a wealthy collector for the sum of 300 guineas. He hires a gang of grave robbers to assist him. The story has always been disregarded because of the (presumed) inaccurate details of the actual digging of the grave in 1794: The men had dug to the depth of three feet, and I now watched narrowly, for, by the clogging of the darker earth, and that peculiar humid state–small I can hardly call it... I know we were nearing the level where the body had formerly mouldered.No shovels but the hands, I whispered, and feel for a skull.There was a long pause as the fellows, sinking in the loose mould, slid their horny palms over fragments of bone. Presently, I got him, said Cull; but he’s fine and heavy.† In light of the new GPR evidence, the details above suddenly seemed remarkably accurate. The established theory up until 2016 was that Shakespeare was buried in a tomb in a coffin. So the following specifics in this story have piqued the interest of archaeologists: Details of the shallow three-foot graveDetails of the body buried directly in the earth with no coffinDetails of soil disruption at the head end of the grave Where Is Shakespeares Skull Today? So if there is truth in this story, then where is Shakespeare’s skull now? A follow-up story suggests that Chambers panicked and attempted to hide the skull in St. Leonards Church in Beoley. As part of the 2016 investigation, the so-called â€Å"Beoley skull† was examined and â€Å"on the balance of probability† was thought to be the skull of a 70-year old woman. Somewhere out there, the skull of William Shakespeare, if it has actually disappeared, may still exist. But where? With intensified archaeological interest sparked by the 2016 GPR scans, this has become one of the big historical mysteries and the hunt for Shakespeare’s skull is now well and truly on.

Dr. Roberta Bondar Biography

Dr. Roberta Bondar Biography Doctor Roberta Bondar is a neurologist and a researcher of the nervous system. For More than a  decade she was NASAs head of space medicine. She was one of the six original Canadian astronauts selected in 1983. In 1992 Roberta Bondar became the first Canadian woman and the second Canadian astronaut to go into space. She spent eight days in space. After her return from space, Roberta Bondar left the Canadian Space Agency and continued her research. She also developed a new career as a nature photographer. While Chancellor of Trent University from 2003 to 2009, Roberta Bondar demonstrated her commitment to environmental science and life-long learning and was an inspiration to students, alumni, and scientists. She has received over 22 honorary degrees.   Roberta Bondar as a Child As a child, Roberta Bondar was interested in science. She enjoyed animal and science fairs. She even built a lab in her basement with her father. She enjoyed doing scientific experiments there. Her love of science would be evident throughout her life. Roberta Bondar Space Mission Payload Specialist on Space Mission S-42  - Space Shuttle Discovery - January 22-30, 1992 Birth December 4, 1945 in Sault Ste Marie, Ontario Education BSc in Zoology and Agriculture - University of GuelphMSc in Experimental Pathology - University of Western OntarioPhD in Neurobiology - University of TorontoMD - McMaster UniversityInternship in Internal Medicine - Toronto General HospitalPost-graduate medical training at the University of Western Ontario, at Tufts New England Medical Center in Boston and at the Playfair Neuroscience Unit of Toronto Western Hospital Facts About Roberta Bondar, Astronaut Roberta Bondar was one of the first six Canadians astronauts selected in 1983.She began astronaut training at NASA in February 1984.Roberta Bondar became chairperson of the Canadian Life Sciences Subcommittee for the Space Station in 1985.She also served as a member of the Premiers Council on Science and Technology.In 1992 Roberta Bondar flew as a payload specialist on the space shuttle Discovery. During the space mission, she conducted a complex set of microgravity experiments.Roberta Bondar left the Canadian Space Agency in September 1992.For the next 10 years, Roberta Bondar led a research team at NASA studying information from dozens of space missions to analyze the bodys mechanisms for recovering from exposure to space. Roberta Bondar, Photographer, and Author Dr. Roberta Bondar has taken her experience as a scientist, doctor, and astronaut and applied it to landscape and nature photography, sometimes in the most extreme physical locations on earth. Her photographs are displayed in many collections and she has also published four books: Landscape of DreamsPassionate Vision: Discovering Canadas National ParksThe Arid Edge of EarthTouching the Earth

Lesson Planning with SIOP Essay Example | Topics and Well Written Essays - 1250 words

Lesson Planning with SIOP - Essay Example Although, A-Level English learners can use various language materials, cognitive mastering, communicative skills and effective strategies for learning and reading expository texts is incredibly significant for an inclusive understanding of the language. As a result of the ever increasing English language requirements, an A-Level English teacher ought to develop an effective plan for managing the complexity of English skills and content as well as ensuring accessibility of English learning instruction to A-Level English language learners. The essay intends to come up with a practical and instrumental plan for A-level English learners’ students. The essay will as well compare and contrasts two major language acquisition theories and explore the success of the identified lesson plan based on the identified theories. The way in which English learning institutions and states deal with issues of language diversity plays a significant role in the definition of the social status of population segments that use exceptional language in the society. Generally, language forms the central conduit for human communication. English language is used in different ways by different people to communicate personal needs, experiences, and expectations. Different A-Level English scholars have used diverse theories to understand the most helpful process of learning English language by A-Level English language learners in diverse geographical, social, and historical backgrounds. In the 1960s, Chomsky observed language development as genetically predetermined and innate phenomenon. According to this theory, human beings are always born with rational and physical abilities to learn and understand language. This instinctive ability makes human being develop the capability of understanding new sentences and wordings. Chomsky suggested that, people develop their language through Language Acquisition Device (LAD). The Language Acquisition Device is

Broca's Aphasia Treatment - Response Elaboration Training (RET) Research Paper

Broca's Aphasia Treatment - Response Elaboration Training (RET) - Research Paper Example Damage to the Broca’s area can cause severe aphasia or difficulty in speech. An element through which Broca’s aphasia can be treated is a technique known as the Response elaboration training. This essay would further discuss the etiology of Broca’s aphasia along with its option of treatment in adult patients (Guyton & Hall 2011; Fazio et al 2009). Aphasia generally describes a condition in which an individual has impaired language skills. It can occur due to damage to the regions of the brain which are responsible for language. Broca’s area is a non fluent type of aphasia which occurs in the frontal lobe of the brain. In this type of aphasia the individuals are not able to speak whole words or they have difficulty speaking them. In this type of aphasia some motor movements of the individual are also affected because the frontal lobe is also affected. Commonly aphasia occurs due to accidents which harm the structures in the brain, a tumor in the brain, infection of the brain and dementia. It is because of these problems that the sensory pathways do not transmit the signals properly and hence aphasia occurs (Guyton & Hall 2011; LaPointe 2005). Broca’s aphasia is characterized by problems in speaking or writing language. It is also called motor aphasia, expressive aphasia or non-fluent aphasia. The individuals are not able to speak fluently and hence have difficulties in making up sentences. The individuals face difficulties when speaking up full words. The individuals are not able to make up sense with their sentences. For example individuals would just use two words such as ‘glass, table, where the individual tries to say that the glass is on the table. (Fazio, 2009). At first it was believed that Broca’s aphasia was only associated with language comprehension but recent research suggests that it also affects other portions of cognition through which individuals cannot perform and understand actions properly (Grafton et al 1996;

Introduction to the microbial world history of microbiology Essay Example for Free

Introduction to the microbial world history of microbiology Essay Part A. This letter is in response to your story which was published in your website and broadcasted in your stations regarding Edward Jenner as the most prolific microbiologist that ever lived and have contributed much to the improvement of microbiology and public health. I would like to make a point that several other scientists have contributed much to that of the works of Jenner on eradicating small pox virus by vaccination. He may have started the use of vaccines which led to its eradication years later; however, it should not be mistaken to be the most significant microbiological contribution. Take an example the work of Joseph Lister on 1867 regarding antiseptics (Prescott et al., 2005). Like any other scientist during his time, works on antisepsis was not an overnight job; he worked carefully and tested his theories over and over again, until such time that he perfected it (Roediger, 1990). By thoughtfully thinking of what may cause pus formation in surgical wounds, he experimented with rags and phenol and used it as wound dressings. Sure enough, his patients did not develop gangrene after being dressed with carbolic acid or phenol treated rags. Later on, he improved on excluding bacteria from his operating suite by incorporation of clean environment as a prerequisite in aseptic surgery (Lister, 1909). See more: how to write an academic introduction In modern days, Lister’s work on antiseptic surgery had decreased much of the deaths caused by hospital-acquired infections brought about by practicing of good science (Pasteur and Lister, 1996). By applying his notion of the germ theory via his promotion of environmental cleanliness and sanitation, he inculcated the modern medical practitioners with standards of disease prevention that ultimately lead to reduction of major infections like tuberculosis (Osborn, 1986). Most notably, in his honor, Listerine ® was named after him. In recognition of his efforts, the British Medical Journal recently stated that â€Å"he saved more lives by the introduction of this system than all the wars of the 19th century together had sacrificed† (Nester et al., 2007). To conclude that Lister was more prolific than Jenner, the Jenner Institute of Preventive Medicine in Britain was changed to its current name, the Lister Institute of Preventive Medicine (The Lister Institute). Another notable scientist is in the persona of Dr. John Snow. John Snow, in 1849 published his works entitled, â€Å"On the mode of communication of cholera.† In his research, Snow began to hypothesize that cholera was indeed transmitted by a common source, and sure enough he pin pointed it to a contaminated water pump in Broad Street (Thrusfield, 22007). Though highly criticized and much of his researches were dismissed, he never did falter in seeking out the truth. Despite of these obstacles, he never faltered to show the good qualities of an epidemiologist: good record keeper, determined, dedicated and highly skilled (Stanwell-Smith, 2002). A good record keeper, he was a very keen observer and he never did forgot to take into accounts this minute details that allowed him to solve the mystery of the cholera epidemic in London. Moreover, determined and dedicated to his work even though criticisms were all around him and yet a highly skilled scientist never did show attitudes that will hinder him from succeeding (Prescott et al., 2005). His works have led people to dub him as â€Å"the father of epidemiology.† Sure enough, epidemiology and public health cannot have gone a million step without the initiative of the medical doctor who was once criticized for hypothesizing something at that time which cannot be proven until later years where, the bacteria responsible for the disease was isolated. It may be another story of another scientist, but without Snow, nothing not even the prevention and determination of the occurrence of diseases can progress (Stanwell-Smith, 2002). Sure enough, Jenner may have helped in improving disease prevention by first creating the vaccine and subsequent studies leading to its development, it cannot be disclosed that Lister and Snow, did more achievements in the field of microbiology and public health per se. It may be fitting to say that Jenner may be a great microbiologist, it is only proper to also uphold and acknowledge other note taking efforts of these other microbiologists. Part B. In the summer of 1999, the first human case of West Nile Encephalitis in the western hemisphere was documented. By the end 0f 2002, the WNV epidemic have resulted to at least a total 4,156 human cases (with 2,943 meningoencephalitis case and 284 deaths), 16,741 dead birds, 6,604 infected mosquitoes and 14,571 equine cases. This epidemic was the largest recognized arboviral meningoencephalitis epidemic in the Western Hemisphere (CDC, 2003). The Virus Western equine encephalitis is a member of the Genus Flavivirus under the Family Flaviviridae (Tortora et al., 2007). The virions are spherical and around 50 nm in diameter. It is widely distributed throughout the Americas, especially after the onset of the epidemics in 2002. It is maintained in an endemic cycle involving domestic and passerine birds and Culex sp. serving as the vector host (Murphy et al., 1999 ).   WNV infection in humans produces either asymptomatic infection or mild febrile disease, sometimes accompanied by rash, which should be differentiated from dengue hemorrhagic fever. The human case-fatality rate in the U.S. has  been 7% overall with 10% of patients having neuroinvasive WNV disease (CDC, 2003). The Outbreak Although unknown how or when WNV was introduced into North America, international travel of infected people, importation of infected birds or mosquitoes or migration of infected birds are all possibilities and cannot be ruled out. Overwintering mosquitoes during the winter of 1999 to 2000 have been the mode wherein the virus has propagated throughout New York. It has then undergone several cycles of overwintering and by the end of 2002 has affected 44 states, including the District of Columbia. It has now been proven that the mosquito carry the virus and have traveled initially from New York to nearby states infecting other animals, most notably humans. (CDC, 2003). Control and Prevention Prevention and control of WNV encephalitis was accomplished effectively through a series of comprehensive efforts and programs including integrated pest management. It should be taken into consideration that the priority prevention for this type of disease is destruction of mosquito habitats which serve as the main vector. Likewise, sanitation and water management greatly reduced the total number of cases from that of 2002 to a tolerable one. (CDC, 2003)

Canterbury Tales :: essays research papers

The Canterbury Tales is a collection of accounts about a journey pilgrims made to and from the Canterbury Cathedral, composed by British writer Geoffrey Chaucer in the late 1300’s. â€Å"Chaucer greatly increased the prestige of English as a literary language and extended the range of its poetic vocabulary and meters† (Encarta 1). In the tales, the host offers a contest to the pilgrims which requires them to tell four stories during their trip . Chaucer ingeniously integrates the episodes with one another and also resplendently describes the personality, behavior, and general way of life of a variety of aspects of society in the Medieval Ages. The Canterbury Tales consists of twenty-four tales, two of which are unfinished. One of these unfinished accounts is the Tale of Sir Thopas. The Tale of Sir Thopas begins with the narrator describing a fair and gallant knight who is from the far country of Flanders. It continues on characterizing this knight, Sir Thopas, as a handsome man who was skilled at hunting, horse riding, wrestling, and archery. All of the woman of the land longed for him, but Sir Thopas forsake all of them. Then one day, riding through the forest, the knight hears beautiful birds singing songs of love. Upon hearing this, Sir Thopas hurries to ride away because his heart is sore as there is no woman in the world to his make.   Ã‚  Ã‚  Ã‚  Ã‚  The knight then recalls a dream he had where his darling would be an elf-queen. He continued riding until he found a secret place called the Land of Faery. There he met a great giant whose name was Sir Oliphant. The giant threatened Sir Thopas to leave the land where the Queen of Faery resides or he would be killed. After hearing this Sir Thopas answered that when he has his armor both of them would fight to the death. This scene is an example of how Chaucer â€Å" Gives the Tale of Sir Thopas a hilarious send-up as opposed to other more serious tales that indirectly disparage English literature† (Payne 33).   Ã‚  Ã‚  Ã‚  Ã‚  Sir Thopas returned to his kingdom where he prepared himself for his battle against the giant. His merry men cheered him with tales of old romances, they brought him sweet wine, a royal spicery of ginger bread, and fine linen to cover himself. Then he dressed himself in ornate armor. He had a spear of fine cypress wood, a saddle of rewel bone, and a shield of solid gold.

The Ethylene Propylene Diene Terpolymers Engineering Essay

INTRODUCTION AND OBJECTIVESEthylene-propylene-diene terpolymers ( EPDM ) have been widely used in industrial applications because of their first-class opposition against heat, ozone and weathering, every bit good as their unusual handiness of accepting high burden of fillers [ 1-3 ] . Support in the public presentations of gum elastic compounds, such as tensile strength, resiliency, wear opposition and flex opposition, can be achieved by lading the compounds with particulate fillers. Different classs of C black are the well-known conventional fillers used in EPDM gum elastics compounds [ 4 ] . Increasingly, mineral fillers like silicon oxide and clay have attracted more attending as they cost less and give less wellness jeopardies [ 4 ] . But due to the hapless silica-rubber bonding, the support by silicon oxide has non been to the full exploited [ 4, 5 ] . The handiness of silanised silicon oxide, which is normally obtained by pre-treating silicon oxide with Bi ( 3-triethoxysilylpro pyl ) tetrasulphane ( TESPT ) , a yoke agent, adheres silicon oxide to the gum elastic [ 6 ] . Furthermore, it is attractive that the sulphur-bearing bifunctional organosilane can besides assist to bring forth crosslinks between gum elastic ironss with the presence of gas pedals and activators at elevated temperatures, i.e. 140-240A °C [ 5-12 ] . The presence of TESPT improves the remedy procedure in silanised silica-filled EPDM gum elastics with other common vulcanizing systems. Though many research workers have made attempts to look into different remedy systems for EPDM gum elastics [ 3, 4, 13-17 ] , the inquiry on the efficiency of remedy systems for commercial production remains unfastened. That gives the aim of this undertaking which is as following: Using different remedy systems to crosslink silanised silica-filled EPDM gum elastic ; Assess efficiency of the remedy systems ; Choose the most efficient one for bring arounding the gum elastic. This literature reappraisal foremost introduces the basic background of EPDM gum elastic, including composing, chemical construction and corresponding belongingss and industrial applications in Section 2. Then a brief overview of the preparation of silanised silica-filled EPDM gum elastic compounds is given in Section 3, followed by the elaborate debut of recent plants on fillers and remedy systems for silanised silica-filled EPDM gum elastic in Sections 4, 5 and 6. Finally, the undertaking program will be discussed.BASIC BACKGROUND OF EPDM RUBBERTerpolymerisation of ethene, propene and a non-conjugated diene gives EPDM gum elastic with a concentrated ethylene-propylene anchor and unsaturation site in the side group, introduced by diene monomers [ 17 ] . Generally, ethene and propene monomers are the major constituents in an EPDM, supplying inherently first-class opposition against debasement by heat, visible radiation, O, and, in peculiar, ozone [ 18 ] . The little sum of non-conjug ated diene monomers place the reactive unsaturation sites available for sulphur vulcanization or polymer alteration chemical science, as the dienes are so structured that merely one of the dual bonds will polymerize [ 19 ] . Figure 1 EPDM ternonomers The three co-monomers used in industry are present in Figure 1. Each diene monomer incorporates with a different ability of triping long concatenation ramification or polymer side ironss, hence affect the processing and vulcanization procedure [ 20 ] . The most normally used termononer is ethylidene norborne ( ENB ) as it can integrate easier and has greater responsiveness with sulphur vulcanization [ 19 ] . The chemical construction of EPDM with ENB termonomer is illustrated as follows: Figure 2 Chemical construction of EPDM A general sum-up of belongingss of EPDM gum elastic is listed in Table 1 below. Table 1 Properties of EPDM gum elastics Polymer Properties Mooney Viscosity, ML ( 1+4, 125A °C ) 5 to 200 Ethylene Content ( wt. % ) 45 to 80 Diene Content ( wt. % ) 0 to 15 Specific Gravity ( gm/ml ) 0.855 to 0.88Vulcanisate PropertiesHardness ( Shore A Durometer ) 30 to 95 Tensile Strength ( MPa ) 7 to 21 Compaction Set B, ( % ) 20 to 60 Elongation ( % ) 100 to 600 Useful Temperature Range ( A °C ) -50 to +160 Tear Resistance Fair to Good Abrasion Resistance Good to Excellent Resilience Fair to Good Electrical Properties Excellent EPDM is the fastest turning man-made gum elastic having to its superior ozone and thermic opposition over other diene gum elastics and its burden of fillers and plasticizers to an highly high degree [ 18 ] . EPDM has found widespread applications in [ 18 ] : Automotive applications, such as seals, hosieries and profiles ; Construction applications, such as roof sheeting, profiles, and seals ; Electrical overseas telegrams and jacketing ; Moulded contraption parts ; besides is Blended with other gum elastics and thermoplastics.EPDM RUBBER FORMULATIONFillers for EPDM RubberDue to the non-crystallising nature of EPDM gum elastic, support is required for EPDM gum elastic, since the mechanical belongingss of the unfilled gum elastic are rather hapless. Carbon black is the most widely used filler for reenforcing EPDM gum elastics, but silicon oxide, clay, talc and some other mineral fillers are besides used [ 19 ] . Increasingly, more attending is being paid to silica [ 1, 2, 4, 15, 16, 21-25 ] . To accomplish full development of support by reenforcing fillers in EPDM gum elastics, C black and other fillers must be good dispersed. Good support can give EPDM gum elastics with high tensile strength, good tear opposition and improved scratch opposition. Furthermore, a well-mixed batch besides improves the processability for bulge, calendaring and modeling [ 19 ] . The reenforcing fillers and their effects on EPDM gum elastics will be discussed in item in Sections 4 and 5.Remedy Systems for EPDM RubberAs mentioned before, the incorporation of unsaturation sites allows the sulfur vulcanising of EPDM rubber. Sulphur remedy is the most widely used method, busying about 80 % of EPDM applications [ 17 ] . EPDM gum elastic can besides be vulcanised in a peroxide remedy system. Rubber vulcanised by sulfur remedy system can suit more emphasis and exhibit higher elongation at interruption, while the advantage of peroxide remedy over sulphur remedy is the formation of thermo-stable carbon-carbon bonds alternatively of thermo-labile sulphur-sulphur bonds, as the dissociation temperature and energy of sulphur-sulphur bonds is lower than that of carbon-carbon bonds [ 17, 26 ] . Hence higher effectivity of heat opposition of EPDM gum elastic can be obtained by peroxide remedy systems. The treatment of remedy systems for EPDM gum elastics will be unwrapped in Section 6.Other AdditivesOther normally used additives in EPDM rubber compounds are plasticizers, s ofteners and treating AIDSs. Naphthenic oils have been the most widely used plasticizers as they have the best compatibility with EPDM gum elastic and lowest cost. Paraffinic oils are normally used for elevated-temperature applications or in colored compounds due to the lower volatility and higher UV stableness. Stearic acid, Zn stearic and other internal lubricators are frequently used as processing AIDSs in EPDM rubber compounds. The presence of tackifier or non is dependent on if there is a demand for presenting tack as EPDM gum elastic compounds are inherently non tacky [ 19 ] . Different preparations of EPDM rubber compounds consequence in a assortment of applications. A typical formula for C black-filled EPDM gum elastic for sheeting application is shown in Table 2 below. Tiwari and colleagues [ 27 ] studied consequence of different interventions of silicon oxide on silica-filled EPDM gum elastic belongingss and the basic preparation for silanised silica-filled gum elastic is given in Table 3. Table 2 Typical formula for C black-filled EPDM sheeting [ 19 ] Components Amount ( phr ) EPDM A 100 N – 347 black 120 Talc 30 PARAFFINIC oil type 103B 95 Zinc oxide 5 Stearic acid 1 MBTS 2.2 TMTD 0.65 TETD 0.65 Sulfur 0.75 Table 3 Basic preparation for silanised silica-filled individual EPDM gum elastic Components Amount ( phr ) EPDM 100 Silica 50 ZnO 5 Stearic acid 2.0 Silane ( TESPT ) 4 Sulfur 1.04 N-cyclohexylbenzothiazole-2- sulphonamide ( CBS ) 1.5 Tetramethylthiuram disulphide ( TMTD ) 0.8 Zinc dibenzyldithiocarbamate ( ZBEC ) 1.5Fillers USED IN EPDM RUBBERCarbon Black: A Conventional FillerCarbon inkinesss are the most widely used reenforcing fillers in gum elastic industry since the find of their effectivity of bettering the physical and mechanical belongingss of natural elastomers in 1904 [ 12 ] . Different classs of C black have been used in EPDM gum elastics for industrial applications, such as roof sheeting and automotive profiles and many research workers have studied about the mechanical behavior of C black reinforced EPDM gum elastics. Ghosh and Chakrabarti [ 28 ] reported effects of different sums of C inkinesss on the physical and mechanical belongingss, ageing behavior and conduction of EPDM rubber compounds and the rheological behavior of EPDM gum elastic in bulge processing. Osanaiye [ 29 ] used sinusoidal shear flows to analyze the effects of C black, temperature and shear frequence on dynamic mechanical belongingss of EPDM rubber compounds. The effects of different sums of carry oning C black filler on thaw rheology and relaxation behavior of healing free EPDM gum elastic by cone home base viscosimeter was reported by Ghosh and Chakrabarti [ 30 ] . Abd-El Salam and colleagues [ 31 ] used inactive and dynamic analysis to analyze consequence of different vulcanizing systems on the mechanical belongingss of butyl rubber/ EPDM general furnace black. Cavdar, S. et al [ 3 ] reported a comparative survey on mechanical, thermic, viscoelastic and rheological belongingss of cured C black filled EPDM gum elastic. There are many more illustrations of research on other facets of C black reinforced EPDM gum elastics. For illustration, conductive gum elastics have been made by adding conductive C inkinesss into EPDM and its blends by Das, N. C. et Al [ 32 ] . The electrical and mechanical belongingss have been studied.Silica: A Novel FillerRecently, man-made silicon oxide is going more popular as reenforcing filler in EPDM gum elastics because they have proved to be every bit effectual as C inkinesss [ 12 ] . Furthermore, silica offers several advantages over C black: in tyre paces, a higher wear opposition and better wet-grip with a lower turn overing opposition can be obtained by utilizing silicon oxide instead than carbon black [ 1 ] . Besides, silica-filled compounds are really suited for light coloring material applications.Problem and TreatmentsThe support of silicon oxide in EPDM gum elastic has non reached the coveted degree because of the hapless silica-EPDM bonding. The surfaces of sili con oxides have siloxane and silanol groups, which make the filler acidic and polar [ 7 ] while EPDM gum elastic is non-polar. When the polar silicon oxide is assorted with non-polar and olefinic hydrocarbon gum elastics, e.g. EPDM, hydrogen-bond interactions between polar siloxane or silanol groups in agglomerates are more likely to happen than the interactions between silicon oxide and rubber [ 1 ] , ensuing in hapless compatibility of hydrocarbon gum elastics with silicon oxide. Furthermore, the acidic silanol groups interact with the basic gas pedals, spread outing the remedy times to an unacceptable degree and take downing the crosslinking denseness [ 5 ] . The polar surface of silicon oxide will besides be given to absorb wet and this influences remedy and belongingss of the cured gum elastic [ 5 ] . Additionally, the viscousness increases with increasing sum of silicon oxide filler and if the viscousness is excessively high, the processability will be reduced and inordinate w ear and tear of the processing machine will take topographic point [ 5 ] . However, the handiness of specific matching agents makes the usage of silicon oxide in EPDM rubber compounds possible. Bifunctional organosilanes are normally used to better the compatibility between silicon oxide and hydrocarbon gum elastics by modifying the surfaces of silicon oxide [ 1 ] .Silanes and Silanised SilicaBifunctional silanes can be used to chemically associate an organic stuff to an inorganic substrate. The rule purpose of utilizing silanes to respond with silica involves cut downing ablating hydrophilicity of silicon oxide and presenting a new organo – functional groups onto the silicon oxide surfaces [ 1 ] . In the instance of sulphur-cured compounds, sulphur-functional silanes perform best and for peroxide-cured compounds, unsaturated silanes such as vinylsilanes are recommended. In footings of sulphur-cure systems, the usage of Bi ( 3-triethoxysilylpropyl- ) tetrasulphane ( TESPT ) ( Figure 3 ) as a yoke agent is good established, since foremost introduced in 1991 in a practical application in green tyres by Rauline [ 33 ] .. Figure 3 Chemical construction of TESPT TESPT possesses ethoxy groups and tetrasulphane groups. The ethoxy groups react with silanol groups on the silicon oxide surfaces via hydrolysis mechanism [ 33 ] , taking to the strong covalent silica-filler bonding. The tetrasulphane groups are no-good reactive and therefore stable rubber-silica bonding can be achieved via sulfur crosslinking. Bis ( 3-triethoxysilylpropyl ) -disulphane ( TESPD ) was subsequently introduced chiefly to get the better of the pro-scorching job of TESPT, as the sulphur-sulphur dissociation energy of TESPD was lower than that of TESPT [ 33 ] . The silanisation of silicon oxides are normally obtained by two attacks. Silica and silanes are assorted preliminarily at an optimal temperature and reaction clip, or, instead, they can be mixed in situ during the commixture procedure [ 5 ] . The latter is the more normally used method [ 34 ] . A good silanisation is required as it yields best support and reduces compound indurating during storage. A certain sum of H2O can speed up the silanisation. The optimum wet content is suggested to be around 3-6 % [ 34 ] . The chief influences on the in situ silanisation of silica-silane filled compounds are summarised in Figure 4. Furthermore, if silicon oxide is used in a blend with, e.g. , C black, relatively more silane is required as silane is less likely to make the silica surface quantitatively in a given commixture clip [ 34 ] . In these instances, silanised silicon oxide obtained by the pre-treatment is advisable. Optimum silanisation And Short commixture times Release of ethyl alcohol T a† Ã¢â‚¬Ëœand T a† Ã¢â‚¬Ëœ Release of ethyl alcohol Ta† Ã¢â‚¬Ëœand ta† Ã¢â‚¬Ëœ Good silicon oxide scattering I ·a† Ã¢â‚¬Ëœas Ta† Ã¢â‚¬Å" Complete matching reaction Ta† Ã¢â‚¬Ëœ and T a† Ã¢â‚¬Ëœ Avoid pre-crosslinking T a† Ã¢â‚¬Å" and T a† Ã¢â‚¬Å" Fast transit procedures I ·a† Ã¢â‚¬Å"as T a† Ã¢â‚¬Ëœ High mobility of the silane ; little size Best rotor and blending chamber geometry Figure 4 chief influences on the silanisation reaction [ 34 ] Apart from sulphur vulcanization, the add-on of vinylsilanes is normally applied to better the mechanical belongingss of peroxide-cured compounds. The general construction of vinylsilanes is shown in Figure 5. Figure 5 generalized construction of vinylsilanes In contrast to the reasonably high dose of sulphur-functional silanes in merchandises necessitating high mechanical belongingss, a strong support can be achieved by the incorporation of merely 2 parts by weight Si 225 ( VTEO ) per silicon oxide [ 34 ] . Adding more extremist instigator or activators can ensue in higher crosslink densenesss [ 34 ] . However, the applications of silanised silicon oxide are largely focused in natural gum elastic ( NR ) , styrene butadiene gum elastic ( SBR ) , and polybutadiene gum elastic ( BR ) . Very few research works has been published on the effects of silane on EPDM gum elastics, but there are still some. Kim [ 33 ] reported consequence of TESPD on the processability and mechanical belongingss of EPDM rubber. Taikum and Luginsland [ 16 ] studied the function of silane-rubber yoke in sulfur, peroxide and metal oxide bring arounding systems for EPDM gum elastic. Das et al [ 4 ] showed that the presence of TEPST increased the content of bound gum elastic in silica-filled EPDM compounds, which was critical to the mechanical belongingss of the gum elastic.Other TreatmentsOther matching agents Besides silane, several other matching agents have been employed to modify the silica-EPDM bonding. Das et al [ 4 ] usage Bi diisopropyl thiophosphoryl disuli ¬?de ( DIPDIS ) , to modify EPDM rubber alternatively of silicon oxide by two-stage vulcanization technique. The effects of TAC ( Triallyl Cyanorate ) as a yoke agent on hardening and mechanical belongingss of silica-filled EPDM gum elastic were studied by Abtahi and associates [ 1 ] . Others methods Tiwari et al [ 23 ] treated the surfaces of silicon oxide by plasma-polymerisation with acetylene monomer and one twelvemonth subsequently, the comparative survey of plasma-thiophene and -acetylene coated silicon oxide in EPDM support was reported [ 27 ] . Tan and Isayev [ 22 ] treated silicon oxide utilizing a coaxal supersonic extruder and investigated the effects on belongingss of ultrasound-treated silicon oxide on filled EPDM gum elastic.Other fillersIn most instances, C black and silicon oxide are used to reenforce EPDM gum elastics. Some other sorts of fillers have been added to EPDM rubber matrix and their effects been investigated, affecting montmorillonite ( OMMT ) nanofiller [ 35 ] , nano-zinc oxide [ 36 ] , Sm2O3 [ 26 ] , short cyanuramide fibers [ 37 ] , ash/halloysite [ 38 ] and so on.Effects OF FILLERS ON PROPERTIES OF EPDM RUBBEREffectss of Carbon BlackAs mentioned before, research workers have studied a batch about the effects of adding C black on the mechanical belo ngingss of EPDM rubber, demoing that the belongingss were improved significantly [ 3, 28-32 ] . Cavdar and associates [ 3 ] reported that the Young ‘s modulus, Shore A hardness, and compaction force over distortion ranage increased with increasing content of C black, while the elongation at interruption reduced ( Figure 6 ) . Figure 6 Effectss of C black content on ( a ) mechanical belongingss ; and ( B ) rheological belongingss of EPDM rubber [ 3 ] . The Young ‘s modulus was most filler content medium as the value increased aggressively with sum of C black. In footings of rheological belongingss, increasing C black content resulted in higher upper limit torsion and the difference between upper limit and minimal torsion, which corresponded to relative crosslinking denseness. The optimal remedy clip decreased with increasing the filler content. Considerable research has been done to understand the mechanism of support. Two chief features of active inkinesss are their surface country and sum construction, which determine the inactive and dynamic in-rubber belongingss and therefore do it possible to orient the public presentation of gum elastic merchandises.Effectss of SilicaEffectss of silicon oxide on the mechanical belongingss of EPDM gum elasticWithout silanes The effectivity of silicon oxide as reenforcing filler in EPDM gum elastic was confirmed by Ichzo and colleagues [ 2 ] who showed that tensile strength had improved by 500 % , tear strength by 400 % and elongation at interruption at 140 % by adding 20 phr of precipitated silicon oxide. They used silicon oxide with different size and demonstrated that an increasing inclination of tensile strength can be achieved when the size of silica atom decreased. The hardness of EPDM gum elastic increased with the filler burden but it was non particle size dependant. They besides found that silicon oxide sums size distribution affected the mechanical belongingss and it deserved more attending. With silanes Das [ 4 ] indicated that the Young ‘s modulus, tensile strength and crosslinking value of silica-filled EPDM gum elastics increased well when 1-2 phr of TESPT was added, while the elongation at interruption decreased, as illustrated in Figure 7 below. ( B ) ( a ) ( vitamin D ) ( degree Celsius ) ( degree Fahrenheit ) ( vitamin E ) Figure 7 Consequence of TESPT on the mechanical belongingss of EPDM rubber compounds: ( a ) modulus at 100 % elongation ; ( B ) modulus at 300 % elongation ; ( degree Celsius ) tensile strength ; ( vitamin D ) hardness ; ( vitamin E ) elongation at interruption ; ( degree Fahrenheit ) crosslinking value [ 4 ] .Consequence of silicon oxide on treating belongings of EPDM gum elasticAs mentioned earlier, adding silicon oxide to EPDM gum elastic will do the processing more hard as the viscousness increases significantly when a large sum of silicon oxide is involved [ 5 ] . However, the handiness of silanes such as TESPT or TESPD weaken the interaction between silica atoms as the ethoxy groups in silane react with the surfaces of silicon oxide by the silanol groups, taking to a alteration in interfaces between the polymer-polymer, polymer-silica and silica-silica [ 33 ] . Hence, it reduces the viscousness and improves the processability of the gum elastic compounds [ 5 ] . Kim [ 33 ] reported that the add-on of TESPD to silica-filled EPDM gum elastic yielded lower Mooney viscousness, heat coevals and bulge force per unit area build-up through an extruder, which made treating easier.Effectss of silicon oxide on thermic belongings of EPDM gum elasticMadani [ 39 ] studied the thermic belongings of gamma radiation cured silica-filled EPDM via thermohydrometric analysis ( TGA ) and demonstrated that the presence of silicon oxide reduced the rate of debasement and the weight loss of vulcanisates. This was due to the improved adhesion between silicon oxide and EPDM rubber matrix. He besides stated that thermic belongings of silica-filled EPDM gum elastic was determined by the burden of filler, filler size and construction, filler-matrix interactions and processing technique.Consequence of silicon oxide on the ageing belongings of EPDM gum elasticAirplanes et al [ 15, 40 ] used gamma radiation to age unfilled and filled EPDM gum elastics at room temperature and at 80A °C to analyze the influence of silicon oxide on the gum elastic debasement. They evidenced that adding untreated silicon oxide accelerated the polymer stage debasement due to the formation of auxiliary groups triggered by silica irradiation. If silane-treated silicon oxide was presented, the debasement acceleration was delayed.Effectss of silicon oxide on the electrical belongings of EPDM gum elasticRaw EPDM gum elastic is an dielectric with a conduction of about 10-14 S-1 [ 39 ] . It was proved that the add-on of inorganic fillers such as silicon oxide increased the condu ction of polymer [ 39 ] . Madani [ 39 ] investigated the fluctuation of dielectric changeless ( ) of some healed EPDM and silica-filled EPDM gum elastics as a map of frequence and found that was filler content dependant: it increased up to 10 phr, and so decreased with increasing burden. He pointed that the addition was due to the polar groups present on silicon oxide surfaces, and that the lessening was due to the increasing system denseness and the extent of orientation of dipoles.Effectss of scattering of silicon oxide on the belongingss of EPDM gum elasticFiller scattering has a distinguishable consequence on the belongingss of gum elastic compounds. Poor scattering has a negative consequence on gum elastic belongingss by making structural defects [ 5 ] . Polmanteer and Lentz [ 41 ] demonstrated that some belongingss such as tensile strength and tear strength improved as the filler scattering quality increased after they examined consequence of scattering of silicon oxide on the belongingss of some sulphur-cured gum elastics. To obtain a better scattering of fillers in gum elastic compounds, increasing commixture clip is an efficient method, nevertheless, at the cost of take downing the molecular weight of polymer, which leads to the decrease in mechanical belongingss [ 5 ] . The grade of scattering of filler can be examined by microscopy methods, such as negatron microscopy and atomic force microscopy.CURE SYSTEMS FOR EPDM RUBBERSulphur Cure systemsEvery gum elastic merchandise is vulcanised with its ain specific remedy system, ensuing in assorted belongingss. As already mentioned, the incorporation of pendent unsaturation sites enables that EPDM rubber to be vulcanised by sulphur plus gas pedals. Sulphur remedy is the most widely used vulcanising method for bring arounding EPDM gum elastics, representing about 80 % of the EPDM applications [ 17 ] . Compared with peroxide-cured EPDM gum elastics, sulphur-cured gum elastic compounds are able to suit more e mphasis and exhibit higher elongation at interruption. Basically, three types of sulfur crosslinks are used in elastomers, viz. , monosuphfidic ( C-S-C ) , disulphidic ( C-S2-C ) and polysuphidic ( C-Sn-C ) . The crosslink denseness and the value of Ns are chiefly determined by vulcanizing system and procedure conditions such as remedy temperature and clip. Over the old ages three particular types of remedy systems have been established based on the degree of sulfur and the ratio of accelerator-to-sulphur applied. They are: Efficient vulcanization ( EV ) systems, Semi-efficient vulcanization ( SEV ) systems and Conventional vulcanization ( CONV ) systems. EV systems are characterised by a high ratio of accelerator-to-sulphur or even sulphurless, but incorporating sulphur-donor alternatively. They are normally used in vulcanisates which require an highly high heat and reversion opposition [ 42 ] . CONV systems are vulcanisation systems with a low ratio of gas pedals to sulfur and they can supply better flex and dynamic belongingss but worse thermal and reversion opposition. A semi-efficient remedy system has an accelerator-to-sulphur ratio in between those of the CONV and EV vulcanization systems. For SEV systems, optimal degrees of mechanical and dynamic belongingss of vulcanisates with intermediate heat, reversion and flex belongingss can be obtained [ 42 ] . The composings of CONV, SEV and EV systems are shown in Table 4. Table 4 the degrees of gas pedals and sulfur in CONV, SEV and EV systems [ 42 ] Type Sulphur ( phr ) Accelerator ( phr ) A/S ratio CONV 2.0-3.5 1.2-0.4 0.1-0.6 SEV 1.0-1.7 2.5-1.2 0.7-2.5 Electron volt 0.4-0.8 5.0-2.0 2.5-12 Increasing accelerator-to-sulphur ratio consequences in increased sum of shorter mono- and disulphidic crosslinks. As the dissociation energy of C-C bonds are larger than that of S-S bonds. Vulcanisates obtained by EV and SEV systems possess a better heat and reversion opposition than those cured by CONV systems. The general influences of the type of vulcanization systems on the construction and belongingss of the vulcanisates are summarised in Table 5. Table 5 vulcanisate construction and belongingss for different remedy systems Features Remedy systems CONV SEV Electron volt Poly-and disulphidic crosslinks ( % ) 95 50 20 Monosulphidic crosslinks ( % ) 5 50 80 Cyclic sulfide ( conc. ) High Medium Low Non-sulphidic ( conc. ) High Medium Low Reversion opposition Low Medium High Heat ageing opposition Low Medium High Fatigue opposition High Medium Low Heat construct up High Medium Low Tear opposition High Medium Low Compaction set ( % ) High Medium Low Furthermore, nitrosamine free or safe hardening bundles were developed for the replacing of remedy systems which develop nitrosamines during vulcanization. N-nitrosamines formed during vulcanization as condensation merchandises from certain gas pedals and azotic gasses and are carcinogenic [ 43 ] . They are generated from some thiuram and dithiocarbamates gas pedals, which are known as ultra-accelerators and normally used in EPDM gum elastic intensifying [ 43 ] . Traditional ultra-accelerators can be replaced by nitrosamine-free systems, but at disbursal of high costs. About all imaginable combination of bring arounding ingredients for EPDM rubber compounds have been evaluated over the old ages [ 42 ] . Five typical remedy systems are listed in Table 6. The alternate nitrosamine free or safe remedy systems are suggested in Table 7. Table 6 Five remedy systems for EPDM rubber [ 42 ] Systems ( phr ) Advantages Disadvantages System 1 Low cost Blooming S 1.5 TMTD 1.5 2-mercaptobenzothiazole ( MBT ) 0.5 System 2 Excellent physical belongingss and fast remedy Scorchy and expensive S 2.0 MBT 1.5 Tellurium diethyl dithiocarbamate ( TDEC ) 0.8 Dipentamethyl thiuram tetrasulphide ( DPTT ) 0.8 TMTD 0.8 System 3 Excellent compaction set and good heat ageing opposition Bloom and really high cost S 0.5 Zinc dibutyldithiocarbamate ( ZDBC ) 3.0 Zinc dimethyldithiocarbamate ( ZDMC ) 3.0 4,4'dithiodimorpholine ( DTDM ) 2.0 TMTD 3.0 System 4 Non-blooming Cure comparatively slow and worse compaction set S 2.0 2,2†²-dithiobenzothiaole ( MBTS ) ZDBC 2.5 TMTD 0.8 System 5 Zinc O, O-dibutylphosphorodithioate ( ZBPD ) 2.0 TMTD 1.0 N-butylbenzothiazole-2-sulfenamide ( TBBS ) 2.0 S 1.0 Fast remedy and good physical belongingss Blooming Table 7 Some NA free options for the remedy systems above [ 42 ] Systems NA free optionsSystem 1S 1.5 S 1.3 MBT 0.5 MBT 0.75 TMTD 1.5 CBS 3.8System 2S 2.0 S 1.5 MBT 1.5 ZMBT 2.0 TDEC 0.8 ZBEC 0.5 DPTT 0.8 ZBPD 2.0System 5ZBPD 2.0 ZBPD 2.5 TMTD 1.0 0 TBBS 2.0 TBBS 2.0 S 1.0 S 1.2 Besides, an activator, such as Zn oxide, is normally needed in EPDM remedy systems to maximize the efficiency of gas pedals and chemical adhesion between the filler and gum elastic.Silanised Silica: a â€Å" Crosslinking Filler †An of import issue must be considered sing the sulphur remedy systems for silanised silica-filled EPDM gum elastic is the fact that the usage of sulphur-functional silanes such as TESPT combine silicon oxide with sulfur into one individual merchandise known as a â€Å" crosslinking filler † [ 6 ] , such as silanised silicon oxide. It can non merely better the mechanical belongingss of gum elastic, but besides can bring forth crosslinks between the gum elastic ironss at elevated temperatures in the presence of gas pedals due to the sulphur-containing groups. Therefore, the vulcanization procedure can be achieved without elemental sulfur being present [ 6 ] . Research has shown that the mechanical belongingss of some vulcanisates improved signific antly in malice of the decrease in the usage of the hardening chemicals [ 6 ] . It was demonstrated that during the vulcanization procedure the formation of both rubber matrix crosslinking web and silica-rubber yoke web occurred at the same time and did non separate. In the presence of elemental sulfur, the two different crosslinking reactions compete for the added sulfur as the sulphur-functional silanes like TESPT are sulphur acceptor [ 34 ] . Therefore the crosslinking construction and the support are determined by the sums of silane and sulfur. The influence of adding different sums of sulfur and silane on the matrix and silica-rubber yoke webs is shown in Figure 8. Figure 8 consequence of the sum of ( a ) added sulfur and ( B ) silane ( TSEPT ) on the crosslinking densenesss of matrix and silica-rubber yoke [ 34 ] It is apparent that increased sum of sulfur enhances the efficiency of the silica-rubber yoke until all the silane is activated. Initially, a little grade of addition in the matrix crosslink denseness is observed, due to the ingestion of free sulfur by the activation of silane. After the full activation of silane, the matrix crosslink denseness additions much faster. With regard to the increasing sum of silane at a changeless sum of sulfur, the entire figure of silica-rubber bonds additions while the degree of the matrix crosslink denseness reduces, owing to the incorporation of sulfur by the silane [ 34 ] . Furthermore, in the instance of TESPD, a disulphide silane, the consequence is more important. Therefore it can be concluded that altering the sum of elemental sulfur and silane consequences in different ratios of the matrix and silica-rubber webs [ 34 ] . Furthermore, mechanical belongingss of silanised silica-filled gum elastic can be predicted because silica-rubber yoke domina tes the modulus and hydrophobation lowers hardness values. Some elaborate effects of silane on the mechanical public presentation of silica-filled EPDM gum elastic have been presented in Section 5.2.1.Peroxide Cure systemsOverviewCrosslinking with peroxides was foremost introduced in 1915, but did n't pull excessively much attending until the development of to the full saturated ethylene-propylene copolymers ( EPM ) [ 42 ] . Many sorts of elastomers can be vulcanised by peroxide remedy systems expeditiously, including NR, SBR, EPDM, BR, nitrile gum elastic, Silicones and fluorocarbon elastomers [ 42 ] . The unsaturation can better the efficiency of peroxide vulcanization [ 17 ] , due to the higher concentration of allylic Hs [ 42 ] . The comparative efficiency of peroxide crosslinking for different elastomers is: BR & gt ; NR and SBR & gt ; NBR & gt ; CR & gt ; EPDM The advantages and disadvantages of peroxide remedy compared to sulfur vulcanization are listed in Table 8 [ 42 ] : Table 8 Advantages and disadvantage of peroxide remedy compared with sulphur remedy Advantages Disadvantages Thermo-stable C-C bonds alternatively of thermo-labile S-S bonds, Scorch free storage of compounds, Simple compound preparation, Low compaction set even at high remedy temperature, It is possible to bring around at high temperatures without reversion, Good electrical belongingss of healed gum elastic, No stain of compounds. Low intensifying flexibleness ; Lack of flexibleness in modulating singe and optimal remedy clip Inferior tensile, tear and flex public presentation, Inferior scratch opposition Higher cost, Sensitivity to oxygen during vulcanization, Smells of peroxide decomposition merchandises.Peroxide remedy of EPDMPeroxide-cured EPDM gum elastics are being widely used for many old ages. They are normally used in window seals, automotive hosieries, roof sheeting, tanking liner, electrical insularities, steam hosieries, roll coverings moldings and so on [ 42 ] .Mechanism of peroxide remedy of EPDM gum elasticThe mechanism of peroxide remedy of EPDM gum elastic and the subsequent practical effects have been reviewed by new wave Duin and colleagues [ 17, 44, 45 ] . In the by and large accepted mechanism of peroxide remedy of EPDM, the major stairss are illustrated in Figure 9. Figure 9 Mechanism for peroxide remedy of EPDM [ 17, 44, 45 ] Thermal debasement of the peroxide initiated by procedure triggered a concatenation of free-radical reactions, taking to the formation of primary alkoxy ( ROaˆ? ) or secondary alkyl groups ( Raˆ? ) . Then the abstraction of H-atoms from the EPDM polymer outputs EPDM macro-radicals ( EPDMaˆ? ) . The following measure is the combination of two EPDM macro-radicals, or the incorporation of a macro-radical to an EPDM unsaturation. If a yoke agent, such as vinylsilanes mentioned in Section 4.2.1.1 ( TAC, trimethylolpropane or m-phenylenbis ( maleimide ) ) , is present, the peroxide remedy efficiency can be increased, as they can heighten the H-atoms abstraction and the undermentioned reactions are repressed [ 1, 17 ] : EPDMaˆ? + ROaˆ? a† Ã¢â‚¬â„¢ EPDM – RO ( No crosslinking ) EPDMaˆ? a† Ã¢â‚¬â„¢EPDMaˆ? ‘ + ( I?-Scission ) The issues of the elaborate mechanism of peroxide vulcanization of EPDM gum elastic remain unfastened, chiefly having to the complexness of the system. Several surveies have been conducted to see farther apprehension of the chemical mechanism of peroxide remedy of EPDM [ 46, 47 ] .Matching agents for peroxide remedy of silica-filled EPDM gum elasticAs antecedently stated, vinylsilanes are normally incorporated in peroxide remedy systems for silica-filled EPDM gum elastic to better vulcanization efficiency and mechanical public presentation of vulcanisates. The effectivity of TAC as a yoke agent for peroxide vulcanization of silica-filled EPDM gum elastic was investigated by Abtahi et al [ 1 ] and concluded that TAC matching agent improved some belongingss such as tensile strength, scratch and resiliency opposition with a proper preparation. They besides used SEM to hold a deep penetration in the interaction between silica filler and gum elastic in the presence of TAC and found that t he grade of support was chiefly affected by the grade of wettability.New DevelopmentsReducing the sulfur content consequences in vulcanisates with better thermal opposition throughout service life, nevertheless, this is at the disbursal of decrease in mechanical public presentations such as dynamic weariness opposition and tear opposition. This via media can be eliminated by utilizing two additives, viz. hexamethylene-1, 6-bisthiosulphate ( HTS ) , a station vulcanization stabilizer and 1, 3-bis ( citraconimidomethyl ) benzine, an anti-reversion agent [ 42 ] . Vulcanization techniques have effects on EPDM gum elastics. Das [ 4 ] studied the efficiency of one-stage and two-stage sulfur vulcanization techniques of silica- filled EPDM gum elastics and reported that alteration of EPDM gum elastic by two-stage vulcanization technique enhanced the interactions between EPDM rubber and silicon oxide. Furthermore, assorted remedy systems can besides be employed to heighten the public presentation of vulcanisates.Undertaking PlanThe overall purpose of this undertaking is to prove some sulfur and peroxide remedy systems to bring around silanised silica-filled EPDM gum elastic to bring forth a gum elastic with good mechanical belongingss utilizing a suited hardening system. The undertaking programs are: Prepare silanised silica-filled EPDM gum elastic compounds with peroxide and bring around the gum elastic with gas pedal and activator via the sulfur in the silane ; Use C black and silanised silicon oxide nanofillers in EPDM gum elastic to measure their effects on the mechanical belongingss of the gum elastic ; Remedy and step the mechanical belongingss of filled EPDM gum elastic to set up consequence of the bring arounding systems and fillers on the gum elastic belongingss.

Ap World Dbq

Jacob Gonzalez AP World 11/29/10 DBQ Even though the economic affects of the flow of silver from middle Sixteenth century to the beginning of the Eighteenth century seem to play out nearly the same in the different countries, the social affects are way more custom based on the source’s pov. Documents 4 & 5 show that silver was the preferred way of pay even though the sources weren't from the same points of views (British and Ming respectfully), however; documents 2 ; 7 show that Spanish ; Chinese have different views on their homeland affects.These documents that are in terms of economy prove to be limited such as document 4 which has an outsider’s view from Britain who is anallyzing the Portuguese use of silver for Chinese goods. In document 5, the Ming writter portrays a statement that in previous years, a simple trade for dyed cloth would suffice, but since the economy is becoming more desiring for silver, comon shops are begining to complicate things with good payme nts of silver. For the Spanish view point, the priest states strait facts saying that according to official records, there was a crazy amount of silver going around.A document that would add to the understanding of the economical effects would be a report from an official document-keeper in Manila that has the ratio between the silver going out vs. the amount of goods from China in order to show who has the advantage in the trade to show something that has a professional view. By contrast to the non opinionated economic affects, the social affects of the silver going around differs thoughts that represent each society involved. Taking a look through the Ming Dynasty’s point of view, they beleive that the greed involved in the silver is corrupting their lives.Interesting enough, all of the documents that are considered â€Å"Social Chinese†, they all are from the Ming officials. In document 1 the Ming official is arguing that if you become too obsessed with silver, you develop a undeniable desire for the silver and you will keep on needing more and more. He is trying to limit the amount of silver the common man will recieve because that same man will be over run by sgreed. In document 3, also by a Ming official, he reports that the respectable olders are blaming the government for the poor amounts of wheat and grain.This document is a little less biased than document one because it shows equal representation of the people to the ruler. The last Ming official document (7) is stating that they should allow foreign trade because the Spanish are making a huge profit selling the Chinese products in the Philippines. His request shows that they would rather have money instead of the country’s pride. For the Spanish, document 2 is from a scholar. This man is whining about the government’s spending. He is saying that the government is spending way too much silver for the Chinese goods: soo much that it is ruining Spain.Finally, document eight is from an British scholar. This scholar is in essence on the same boat as the Spaniard. He is saying that Europe has become too involved in the Asian commodities as well. The difference in his argument is that they are giving away money for worthless, small materials that basically have no point to Europe when it matters. Also, he states that the money that the government is putting into this indulgence will never be refunded to Europe causing them to be in debt.An additional document that would help the best for this is a journal of a traveler that went to the Americas. Because they is from a different society, they would be impartial to the situation, they would be able to give an accurate analysis of the social effects from the silver thrading. Based on the given documents, the economic affects of the silver flow look to be evaluated primarily the same in the accounts from the different societies included, where in social tense; the vantages are different depending on the place they are from and the position of the source in the social heirarchy.

Vegetation Sampling

Vegetation Sampling Abstract Previous studies have revealed quite an interesting phenomenon that occurs in the semi arid lands in western United States. Sagebrush steppe (Artemisia tridentata) is a foundation plant in the Great basin of USA (Inouye 606). This species is ill adapted to the environment is usually vulnerable to environmental effects such as wild fires and other human activities. The destruction of this species often leads to alteration in the ecosystem thus facilitating the proliferation of exotic species.Advertising We will write a custom research paper sample on Vegetation Sampling Barton Road specifically for you for only $16.05 $11/page Learn More This study sought to determine how the removal of herbs and increase in nitrogen affects the abundance herbaceous vegetation. The study was carried out in a designated area that had earlier been divided into different plots that were subjected to different treatments as follows; low nitrogen, high nitrogen, no sage brush and a control plot whose conditions were not altered. The results indicate that the removal of brush and increase in nitrogen deposition leads to increased herbaceous vegetation. Introduction Sagebrush steppe is traditionally associated with western United States (Bechtold and Inouye 74). However, change in the vegetation in those areas has been influence by growing of crops and grazing activities. In addition, the presence and movement of domestic livestock has increased the spread of plant species that were introduced to this area (Inouye 606). Cheatgrass (Bromus tectorium) is one of the annual grass species that were introduced and has now spread to vast areas of the intermountain west (Baker 179). This annual grass species spreads easily because of its ability to complete its â€Å"vegetative growth stage early in the summer, leaving behind dry materials that burn easily† (Baker 179, par. 2). Thus cheatgrass is significantly associated with the cases of wildfires as its litter provides fuel for the wildfires. Several species of shrubs that are found in the sage brush steppe communities and more specifically sagebrush (Artemisia Tridentata) are ill adapted to fire breakouts (Inouye 607 ). Usually after wildfire incidences, sagebrush often disappears leaving behind a plant community that is predominantly composed of herbaceous species (Inouye 607). Studies have indicated that in various plant communities there is always one or a few species that have more access to water or nutrient cycling compared to other species (Rein and Berendse 64). This species of plants are often referred to as foundation species. Some studies have assessed how the foundation species interfere with other plant species in the community (Prevey, Germino and Huntly 39). It is usually observed that if the foundation species is removed from a given ecosystem then more nutrients are made available to the other species. The increase in resource availability has been implicated as a mechanism for the invasion and persistence of the exotic species (Prevey, Germino and Huntly 39). The sagebrush (Artemisia tridentanta) is foundation plant is found in the â€Å"shrub steppe, cold-desert ecosystems of the Great Basin, USA† (Prevey, Germino and Huntly 39, par. 3).Advertising Looking for research paper on ecology? Let's see if we can help you! Get your first paper with 15% OFF Learn More Wildfires and other effects that result directly from human activities have cleared vast traditional habitats of this foundation species. This has caused the exotic herbs to increase in those areas. In direct evidence has suggested that incidences of extensive wildfires may have occurred at intervals of between 30 to longer than 200 years in the sagebrush steppe before the arrival of European settlers (Baker 179). Currently, outbreaks of wildfires occur more frequently at intervals of approximately five years. Human activities have also impacted ne gatively on vegetation cover through increased nitrogen output. This nitrogen mostly results from industrial processes such as the burning of fossil fuels, have released large amounts of nitrogen into the atmosphere (Inouye 607). Normally, nitrogen is often a restraining resource in most terrestrial plant communities that includes those found in arid land (Inouye 607). An increase in the output of nitrogen may lead to an increase in â€Å"plant biomass, shifts in the relative abundance of plant species, changes in plant species richness and it may result in a prolonged period during which annual species dominate disturbed sage-steppe vegetation† (Baker 180, par.4). Rothamsted Experimental station that is located in the UK has for a long time conducted researches on nitrogen cycling in the Ecosystems. Recent data from the station indicate that there is a larger concentration of nitrogen in the atmosphere during winter as compared to summer. This is attributed to the use of cen tral heating systems and to the variations in the direction of wind. This study sought to identify how the removal of shrubs influences the abundance of herbaceous vegetation and the community structure of a sagebrush steppe community. It also sought to determine what changes may occur in the sagebrush steppe community under the influence of increase deposition of nitrogen. Thus the study was carried out in a designated area that was divided into different plots subject to different treatments. This was both a field and lab exercise in which a relationship was to be drawn between the treatment and the effect observed on the plants. Hypothesis Null hypothesis: The removal of shrubs and increase in nitrogen deposition increases the abundance of herbaceous vegetation.Advertising We will write a custom research paper sample on Vegetation Sampling Barton Road specifically for you for only $16.05 $11/page Learn More Alternative Hypothesis: The removal of shrubs and increase in nitrogen deposition does not increase the abundance of herbaceous vegetation Methods Study area The study was carried out on a designated area on Barton road. The area had previously been divided into thirteen plots which were fenced to minimize human and other forms of interference. The study site is located in Bannock county, area that is semi arid with cold winters, moist springs, and warm dry summers. The study area was used as a grazing ground prior to 1990 and was acquired for research purposes n 1996. The area is dominated the Shrub Artemisia tridentata which is mainly responsible for the sagebrush-steppe ecosystem. Experimental design The study site was previously divided into 13 plots and four treatments assigned randomly to the plots. Control (no treatment) plots # 1,5,7 and 11( N=4) Shrub removal. Plots # 4,9 and 13 (N=3) Low nitrogen addition (6Kg/ha/yr). Plots number 2,8 and 12 (N=3) High nitrogen (12 Kg/ha/yr) plots # 3, 6 and 10 (N=3) The plots used in this experiment measured 20 by 20 meters. Field procedures The Tragopogon dubius plants were located in the plots. The maximum height for each flowering stock was measured by a meter ruler and recorded for all the flowering plants plus the number of flowering heads that were present. Any other thing that is unusual and by be relevant to the study was also recorded. For instance, the presence of aphids, whether the plant has been browsed by any herbivore and the appearance of any disease condition. In the same plots that Tragopogon was sampled, the above ground herbaceous biomass was sampled. Two suitable clipping areas were identified on each plot and a pair of scissors used to cut at ground level all herbaceous (no-woody) plant material that was rooted inside the clipping area. Plants that had their roots outside the clipping frame were not clipped. Four sampling sections measuring 1 by 12 meters were created on the outer part of each plot leaving the center intact. The clippin g strips measured 15 x 100 cm and the grass and forbs that had their roots located inside the strip were clipped off at the ground level. Shrubs, mosses, cacti or lichens were not clipped. The grass was then placed in one bag and forbs in the other and then labeled appropriately with the following information; date, plot #, group members and the type of plants. The bags were then transported to the lab, the plants sorted out, the weights measured using a scale and the results recorded in grams. Results The results for the different parameters were measured and tabulated as follows. The results forbs biomass and number of tragopogon plants from same plot were entered in one table as shown. Table 1: Control plots Plot Number # of tragopogon plants Average forb biomass 1 97 0 5 71 0.253 7 79 1.23 11 40 0.04 Average 71.75 0.38075 Table 2: Low Nitrogen PlotsAdvertising Looking for research paper on ecology? Let's see if we can help you! Get your first paper with 15% OFF Learn More Plot Number # of tragopogon plants Average forb biomass 2 39 0 8 51 0.472 12 282 2.86 Average 124 1.111 Table 3: High nitrogen plots PlotNumber # of tragopogon plants Average forb biomass 4 632 3.003 9 399 1.825 13 751 3.048 Average 594 2.625 Table4: No brush plots Plot Number # of tragopogon plants Average forb biomass 3 115 0.243 6 120 0.851 10 102 0.47 Average 112.333 0.521 A bar graph showing the average number of Tragopogon plants in the different plots that received different treatments. A bar graph showing the average levels of forbs biomass in the different plots that received different treatments Height of stalks and the Number of flowering heads The tragopogon stalk height and the number of flowering heads were measured randomly in one section of the different plots and the results tabulated in a table that is not shown due to its length. The data was subjected to statistical analysis to determine whether the height of the stalks influenced the number of flowering heads. According to the p-value there is a significant linear relationship between the number of flowering heads and plant height. R2=0.113915, p value= 3.74E-10, slope= 0.029369, n=327. As plant height increases the number of flowering heads increases due to the increasing regression line. The association between the numbering of flowering heads and plant height is weak based on the multiple R value of 0.338. Only 11% of the variation in the number of flowering heads is explained by plant height. Discussion The results obtained from the above study indicate that indeed the nitrogen deposition and shrub removal have led to the increase in the abundance of herbaceous vegetation. The results showed that forbs clipped from plots that had low nitrogen tended to have lower biomass values as compared to those from plots that had high nitrogen. The number of tragopogon plants is also higher in plots that were treated with high nitrogen as compared to tho se with low nitrogen. This shows the increased nitrogen deposition as a direct result of human activities such as industrial processes is partly responsible for the increase in herbaceous vegetation. Plots that had no brush also indicated higher number of tragopogon plants compared to those whose sagebrush was left intact. For instance, the control plots had an average of 71 tragopogon plants while those with no brush had an average of 112 tragopogon plants. This shows that the removal of brush, which is a foundation plant, altered the ecosystem and thus making more nutrients to be available for the tragopogon. The removal of sagebrush (Artemisia tridentata) and increase in nitrogen deposition are phenomena that occur together and thus can be used to explain the colonization of traditional sagebrush steppe areas with exotic herbs. Measurement of stalk lengths versus the number of flowering heads showed that the increase in plant height leads to an increase in the number of flowering heads. The reason may be that a plant with a long stalk has an advantage over others in terms of access to light for food manufacture. In this study it was revealed that there was more vegetation abundance in the plots that had high nitrogen rates. This reiterates the claim that increased nitrogen deposition resulting from human activities actually affects the ecosystems. Increased human activities have modified the nitrogen cycle through increased fixation by legumes, by energy and fertilizer production, and by the mobilization of nitrogen from long –term storage pools (Rein and Berendse 65). The extra reactive nitrogen is readily transported through the environment, and there is increasing evidence that ecosystems are changing due to eutrophication and acidification (Baker 179). Baker, William. Fire and restoration of sage ecosystems. Wildl Soc Bulletin (2006): 34:177-185. Web. Bechtold, Harry and Richard Inouye. Distribution of carbon and nitrogen after six years of nitr ogen addition and shrub removal. J Arid Environ (2007): 71:122 – 132. 7th December 2010. Inouye, Richard. Effects of Shrub removal and nitrogen addition on soil moisture in sagebrush. Journal of Arid Environments (2006): 65: 604-618. 7th December 2010. Prevey, Janet, et al. Exotic plants increase and native plants decrease with loss of foundation species in sagebrush steppe. Plant Ecol (2010): 207:39–51. 7th  December 2010. Rein, Aerts and Frank Berendse. The effects of Increased Nutrient Availability on Vegetation Dynamics in Wet Heathlands . Vegetation (1998): 1: 63-76. Print.

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