Synthesis and Anticancer Activities of 5-halogeno Pyrimidine

Synthesis and Anticancer Activities of 5-halogeno Pyrimidine SOLID STATE MICROWAVE-ASSISTED SYNTHESIS AND ANTICANCER ACTIVITIES OF N-DERIVATIVES OF 5-HALOGENO SUBSTITUTED PYRIMIDINE 2, 4 DIONE BY TAHIRA SAGHIR ABSTRACT This study will report the synthesis of some substituted 5-halogenated pyrimidine 2,4dione by conventional and solid state microwave assisted methods. Derivitization of 5-halogenated pyrimidine,2,4 dione give predominately N1and N3-subsituted compounds where R may be the alkyl ,aryl, allyl, acyl, cyclohexenyleetc. 5-halogenated pyrimidine 2,4 dione derivatives represent the new group of anticancer and antibacterial agents with potential for development of medicinal application. The application of solid state microwaves to organic synthesis is opening up new opportunities for the synthetic chemist by providing new routes. High consumption of chemicals for prolonged time has adverse effecton environment. This is the key reason to adopt solvent free condition i.e. eco-friendly microwave assisted solid state synthetic routes. Introduction Microwave irradiation has emerged as powerful tool for organic synthesis. In concern with a rapidly expanding applications base, microwave synthesis can be effectively applied to any type of chemistry resulting in faster reaction time from minutes to seconds and improved product yield. The environmental protection has become a global concern and chemical industry is increasingly searching the ways of developing and applying more efficiently and environmentally begins strategies for future sustainable growth. An important part of present effort towards eco friendly synthesis is aimed at reduction of use of solvents as in classical procedures. For this purpose in organic synthesis solid support has made a land mark as the reaction can be performed in dry media or solvent free conditions. Further usage of solid support in conjunction with microwave leads to high yield remarkable reaction rate enhancement high catalytic activity with optimum utilization of energy. The solvent less approach provide an opportunity to conduct selective organic functional group transformation more efficiently and also allows the work to conductin open vessel thus avoiding the risk of high pressure development. 5-halogenated pyrimidine 2,4dione is used as an anticancer agent. A major difference between cancer cells and normal cells are that the cancer cells divide much more rapidly. Rapidly dividing cells require a constant new supply of DNA is the nucleoside,deoxythimidine,which is synthesized in the cell by methylation of uridine. Flouro uracil is administrated to a cancer patient as part of chemotherapy. The body convert it in to flourouridinegreatly decreasing DNA synthesis. A number of pyrimidine bases possess anti viral and anti cancer activities. In addition N1and N3-di substituted 5 halogenated pyrimidine2,4dione also exhibit anticancer , antibacterial and anti fungalactivities. Literature Review Zeng and his coworkersstudied on activity and structure of co-relation which are useful to drug discovery. By modifying the nature and position of substituent or pyrimidine and theirderivatives, a change in biological activity is observed. The synthesis of organic compound and pharmacological evaluation of these compound have been described by them, they have synthesized large number of compound using different reaction condition i.e. liquid phase reaction and solid phase1. Stefeny,PaulaM and their coworkers applied microwave assisted organic synthesis in many formats ranging from traditional solution phase to solvent free reactions2. Verma and Rajender Singh made solvent free synthesis of heterocyclic compounds. They reported that microwave enhanced solvent free synthetic approach has many advantages. These advantages aresimplicity,manipulative ease of the operation and conservation of solvent .A variety of solid state reactions are described that occur rapidly at ambient pressure under solventless conditions and provide ready access to intermediates such as enamines and tosyloxyketones which can be transformed in situ to biologically significant heterocyclic compounds such as isoflav-3-enes, flavones, quinolones, 2-aroylbenzo[b]furans and thiazoles in one-pot operation. Multicomponent reactions under these solvent-free conditions can be adapted for high speed parallel synthesis and are exemplified by assembly of dihydropyrimidine-2(1H)-ones (Biginelli reaction) and imidazo[1,2-a]annulated pyridines, pyrazines and pyrimidines (Ugi reaction) which may have potential in building a library of such compounds3. Verma et al. 2009 found that microwave enhanced solvent free synthatic approach has the features: simplicity manipulative ease of the operation and conservation of solvents as the main advantage. This eco friendly approach is found as an application in facile organic functional group transformation is applied to rapid assembly of hetrocyclic compounds4. Filler and Roberts postulated the importance of fluore containing compounds synthesis in bio and medicinal chemistry e.g. amino acid,anti canceragents,nucleosides, centeral nervous system agents and anesthetic agents5. Sugiyama,H,etal.explained 5 iodo uracil containing DNA-zalpha complex showed photo reactivity. For the high tendency binding it was observed that NH2 terminusZ-alpha and double strained RNA was very profound respectively. In the absence the incidence of Z-alpha,to relate the structure of Z-DNA induced by Zalpha,were perceived in comparison to that with high salt concentration,than the hydroxylated product was meritoriously produced in it specified by Z-alpha.6 Zhan,etal. have made the solvent and catalyst-free synthesis of dihydropyrimidione in one pot conditions under focused microwave irradiation in 2008.7 Andre Loupy has defined microwave chemistry as â€Å"the science of applying microwave irradiation to chemical reaction’’8.In literature we found that initiallyRichard Gedye and coworkers have described the use of microwave irradiation for organic synthesis.After Richard then number of other scientist in the field of organic chemistry reported in detail about various organic reactions which were performed by using this technology. Various reactions in literatureinclude Alkylation,Esterification,Sponification,Condensation ,Oxidation.Reduction.Cycloaddition,Rearrangments,N-acylations,and Olefination.9 Kidwai and Rastogi reported an eco friendly approach for the synthesis of 2 substituted-4-6-diarylpyrimidines using inorganic solid supports for its catalytic roleas well as energy transfer medium is described.The methodology eliminates the usage of solvents during reaction.Microwave assisted basic alumina catalysed reaction is the best as a catalysis as well as reaction time and yield.10 Gedye and Langahave talked about specific microwave effects.11 Loupy and coworkershave published a number of rewiews on solvent-free reactions.12 Kamal Alannan have reported that substituted uracils especially at 5-position play a key role in many metabolic processes. Uracil reacts with halogens such as,chlorine,Bromine. Iodineflorine to give haogen substituted compounds. From the literature it was found that the halogen substituted uracils are important anticancer drugs.13 Zhang and zhou reported the major advantage of solvent-free, for the green synthesis derivatives of heterocyclic compounds. The major advantages of this method are simple experimental and work-up procedures, solvent-free reaction conditions, small amount of catalyst and short reaction time, high yield, and utilization of an inexpensive and reusable catalyst14 Zhao and co-workers reported the advances in the research of pyrimidine derivatives as antitumor drug according to their action on targets.15 Chowdhury and shanker describe the recent development in solvent-free multi component reactions which was the perfect synergy for eco-compatible organic synthesis. The eco-friendly solvent free approach opens up numerous possibilities for conducting rapid organic sunthesis.16 Khosrou and Ali reported the cytotoxicity of synthesized dinitrophenyl derivatives of 5-fluorouracil under hypotoxic conditions on HT-29 cell line under both aerobic and hypotoxic conditions.17 Objectives Solid state microwaves assisted organic synthesis have an impact on drug discovery. The discovery of compounds with improved biological properties can be made more efficient by using new techniques. The objectives of the present research will be: Synthesis of new bio active compounds. Method development for synthesis of new bioactive compounds. Characterization of all synthesized compounds. Pharmacological evaluation. Plan of work Synthesis of 5 -halogen substituted pyrimidine 2,4 dione. Synthesis of N-derivatives of 5-halogeno substituted pyrmindine-2,4-dione. Structure elucidation will be carried out by a.UV/VIS spectroscopy b.FTIRspectroscopy c.NMR d.Mass spectrometry 4.Pharmacological evaluation(anticanceractivities)of synthesized compounds. METHODOLOGY Microwave- assisted synthesis has been applied in many formats ranging from traditional solution phase to solid phase and solvent free reactions. By using dry conditions, the hazards of volatile organic solvents in microwave oven can be eliminated. The solid state synthesis of N-derivatives of 5-halogen substituted of pyrimidine 2,4 dione is of great interest in present research. PLACE OF WORK 1. Lahore College For Women University, Lahore. 2.University of Veterinary and Animal Sciences Lahore. . References 1.Zeng ,J .pharma, Res.16, 304-309, 1999. 2.Stafani, H.A; Gatti, P.M, Synth.commun.30, 2165-2173,2000. 3.Varma, R.S., JournalofHetrocycle.Chem.36, 1565-1571, 1999. 4.Verma, R. S., Journal of Heterocyclic Chemistry, 36(6), 1565 – 1571, 2009. 5.Filler,ACS.Symp.Ser,60, 616,3793,2000. 6.Oyoshi, T.; Sugiyama, H.Journal of Nucleic Acids Research, (1), 123-4, 2001. 7. Zhan, H.W;Wang, J. X. Journal ofChin.Chem,Lett. 19,1183-1185,2008. 8. Loupy, Micro wave in Organic synthesis, Willey-VCH, Weinhein, 2006. 9. Gedye, N; Smith F.E,Can J. Chem. 66,17, 1887. 10. Kidwai, S.Rastogi, Bul and KoreanChen. Soc., 24, 11- 1575, 2003. 11. Lang,F. org. synth., 4,373-386, 1997. 12. Loupy, A.Synthesis1998. 13. Kamal,A; Venka, P, J.Chem, soc., Daton Trans, 3381-339,2002. 14. Zhang, Y; Zhou, Z, Organic chemistry international, 1, 194784-5, 2012 15. Zhao, P; You W, Acta pharmacentica sinica, 47(5):580-7, 2012 16. Choudhury, S; Shankar, M, RSC Adv.2, 4547-4592, 2012 17. Khosrou, Ali , ISI journal of Bio Chemistry and molecular Biology.27/59, 176/290, 2013

School Of Allied Health Science Education Essay

Distance acquisition, sometimes called e-learning is here defined as synergistic acquisition in which the acquisition content is available on-line and provides automatic feedback to the pupil ‘s acquisition activities. Online communicating with existent people may or may non be included, but the focal point of e- acquisition is normally more on the acquisition content than on communicating between scholars and coachs. Distance acquisition and its relationship to emerging computing machine engineerings have together offered many promises to the field of education.A In pattern nevertheless, the combination frequently falls short of what it attempts to accomplish.A Some of the defects are due to jobs with the engineering ; others have more to make with disposal, instructional methods, or students.A Despite the jobs, many users like engineerings such as tight picture and see continued growing in the country. However, distance acquisition is no such advantage is that it is easy, a individual can analyze without go toing categories or talks, while working or making some other class. It is besides a good option for homemakers who are non able to inscribe into classs because they have to take attention of immature kids, merely trade with computing machines and have their ain clip to larn and besides can pass on with coachs and equals via online such as electronic mail, forum and confab. . In distance instruction classs, you would be provided with study stuff and besides would hold to subject assignments on clip. These assignments would be assessed by professors who would direct you feedback. However, if you are be aftering to inscribe into distance acquisition, you need to to cognize about some of the distance larning pros and cons. Like every good thing, even distance acquisition has some disadvantages that can do it look a small inconvenient for people. The job may be due to factors balance between personal and learning jobs. If pupils can non accommodate to the system of distance acquisition, they will confront a different job. In add-on, deficiency of cognition and accomplishments about utilizing engineering and computing machines, linguistic communication accomplishments, particularly English linguistic communication, disorganised manner of larning to blend work jobs, household and survey clip. These are some of the distance acquisition advantages and disadvantages. Before doing a determination, it is of import to weigh the distance larning pros and cons. Though distance acquisition can be termed as a utile and convenient manner to derive cognition and to higher one ‘s making, whether it would profit you would wholly depend upon your personality and attitude. Here we will discourse in more item about the jobs faced by on-line scholars and solutions or suggestions can be followed so that any jobs that arise can be resolved satisfactorily. So it is of import to place the job faced by online scholars because without this cognition, possibly the scholars will lose their focal point and motiveTHREE MAIN PROBLEMS FACED BY BEGINNING ONLINE LEARNERSDespite the promises and obvious advantages to distance acquisition, there are jobs that need to be resolved.A These jobs include equilibrating the combination of work, household and instruction, analyze wonts and deficiency of accomplishments in technology.A Each one of these has an consequence on the overall quality of distance acquisition as a product.A In many ways, each of these issues relates to the others.A This is one of the major job which will do them believe twice earlier decide to progress their survey. The first job faced by on-line distance scholars is in equilibrating the combination of work and instruction. Most of the unfastened and distance scholar normally have many committednesss and duties that they must go to while making their educational ends. Many of them are married, work full clip and of class have kids. If non carried out, all of this can do the pupil bead out from their acquisition. Job duty is already daunting, allow entirely the household and the acquisition, so big scholars have limited clip to make their survey. The undertaking of equilibrating all of the above duty is genuinely disputing for most of them. The 2nd issue is in geting go on-line distance survey wonts. The pupils ‘ mundane environment is really deflecting for most of the pupils. Unlike traditional university pupils who are ever in their acquisition community which supports them most of the clip, on-line distance pupils are non. Distractions such as friends inquiring for dark supper and married woman demanding to travel shopping at the promenade every weekend are among other distractions faced by pupils. Geting some clip in a twenty-four hours to analyze is rather a difficult undertaking to finish. Online distance scholars besides have a difficult clip in being independent and responsible to their ain ego. Most of the clip, there is no 1 about to supervise the pupils larning procedure. The openness of the on-line distance plan gives pupils the freedom to make their acquisition procedure whenever they like but most of the clip, cunctation is the perpetrator. Unfocused position of their acquisition ends besides will do the pupils act irresponsibly towards their acquisition. The 3rd issue is on-line distance scholars besides face jobs in acknowledging and get the hanging strengths and accomplishments in Information Technology ( IT ) . In on-line distance acquisition, engineering is the chief conduit which information and communicating flow. A computing machine with internet entree is normally needed for this procedure and its application will necessitate the user to get the hang certain degree of skill. Some of these jobs arise from a deficiency of preparation, some from the teacher ‘s attitudes about utilizing the engineering, and still others by hardware problems.A It seems to be self apparent that teachers need to be trained to utilize distance larning engineering, but excessively frequently they are not.A The pupil will besides necessitate to hold some basic authorship accomplishments and travel on-line distance bid of English linguistic communication. Unfortunately, non all of the pupils possess the above accomplishments.3.0 THREE LOGICAL AND PRACTICAL SUGGESTION ON WAY TO REDUCE OR ELIMINATE THE PROBLEMS FACED BY BEGINNING ONLINE LEARNERSAdults pupils largely do non hold the luxury of go toing college on a full clip footing because of their work and household duties. They frequently experience jobs which, if non overcome, can ensue in the derailing of their educational ends. There are things that they can make though to assist get the better of the typical jobs that arise. The first solution is scholars must pull off and be after themselves efficaciously in order to equilibrating work, household and survey. They have to use smart clip direction. Avoiding stalling a must. They must be more responsible and have a focussed position towards larning. They must besides larn to better themselves in countries they are missing ( such as composing accomplishments, computing machine accomplishments, note taking accomplishments and English linguistic communication accomplishments ) because non all accomplishments will be taught by the coach. They need to actuate their ain ego by puting accomplishable ends and have a positive attitude. The 2nd solutions are start with less demanding class. There tends to be some ambitious classs that must be completed by pupils, there is seldom a demand that these should be the first 1s studied. Therefore, get down with less disputing 1s that you find more gratifying ab initio so as to construct assurance. This assists in acquiring used to the college atmosphere and the demands of class work once more. Furthermore, every pupil make a survey calender to detailing scrutiny day of the months and assignment due day of the months on a dedicated calender helps to avoid the rushing of assignments at the last proceedingss or exam cram Sessionss. Proper readying leads to good classs, while unequal planning consequences in failure. The 3rd solutions are make certain that internet entree is readily available. Study today is dependent on the cyberspace, forum, e-mail and etc as intermediate communicating. The ability to entree library databases and complete research online is the footing of wining. Besides, electronic entree eliminates the demand of passing many hours working on campus, you can analyze from place alternatively. The practical suggestion on manner to cut down job faced by online scholars are job work outing accomplishments. It gives the chance to develop other utile larning accomplishments such as like pattern specific processs and set theoretical usage when develop concluding abilities and creativeness in happening replies. Other method besides like develop scholars understanding of implicit in rules and do research subject in item. Deciding a survey job may travel through the undermentioned phases as like reappraisal of information. Define job, relate available information to the job with design a work program and methodological analysis and proctor results. Promote them to do a scheme for developing their job work outing accomplishments, which could include reexamining their ain effectivity in this country, placing the chief stairss of the job work outing procedure, placing the standards against which to judge the criterion or quality of results, looking at the job in different ways, simplifying it, doing comparings with researching information and confer withing people to set up critical thought, taking and utilizing methods to undertake the job and taking into history factors that may impact job work outing programs entering information in utile manner.4.0 DecisionThe job faced by get downing on-line scholars is such as like is in equilibrating the combination of work and instruction. Most of the unfastened and distance instruction pupils are older, have occupations and households, so they are should cognize how to pull off clip decently and which one are the precedence. The 2nd issue is in geting go on-line distance survey wonts. The pupils ‘ mundane environment is really deflecting for most of the pupils. Unlike traditional university pupils who are ever in their acquisition community which supports them most of the clip, on-line distance pupils are non, so they must should do a survey calender so that proper readying leads to good classs, while unequal planning can acquire failure consequence. Online distance scholars besides have a difficult clip in being independent and responsible to their ain ego. All the pupil online scholars have to work out all this job with their ain manner and besides have to take more duty on their survey. The 3rd issue is jobs in acknowledging and get the hanging strengths and accomplishments. They must besides larn to better themselves in countries they are missing such as composing accomplishments, computing machine accomplishments, English linguistic communication accomplishments because non all accomplishments will be taught by coach. So pupils should happen their ain opt ions to heighten the accomplishments. If you know if this full job can non decide possibly something might go on in the hereafter. For illustration, on-line scholars possibly will neglect with their survey or acquire bad consequence and blow their money and clip to analyze. As pupil online scholars we should hold purpose for success in our survey. Our ends are for every class participant to win, go forth the class looking at the environing universe with the position of a scientist, experience confident utilizing scientific discipline in his or her ain acquisition, and cognize how to back up inquiry-based acquisition in his or her ain schoolroom.5.0 APPENDIX 1Distance Learning With the history of distance larning embracing so many different larning environments, we need to happen a definition that fits in all situations.A There have been many definitions put frontward in modern literature.A Greenberg ( 1998 ) defines modern-day distance acquisition as â€Å" a planned teaching/learning experience that uses a broad spectrum of engineerings to make scholars at a distance and is designed to promote learner interaction and enfranchisement of larning † .A Teaster and Blieszner ( 1999 ) say â€Å" the term distance acquisition has been applied to many instructional methods: nevertheless, its primary differentiation is that the instructor and the scholar are separate in infinite and perchance clip † .A Desmond Keegan ( 1995 ) gives the most thorough definition.A He says that distance instruction and developing consequence from the technological separation of instructor and scholar which frees the pupil from the necessity of going to â€Å" a fixed topographic point, at a fixed clip, to run into a fixed individual, in order to be trained † .A From these definitions we can see that the pupil and instructor are separated by infinite, but non needfully by clip. This would include tight picture, which is delivered in existent clip. As stated before, this type of unrecorded picture direction is the fastest turning agencies of distance acquisition today.A Because of this, much of the treatment here will be dedicated to the promises and jobs of this engineering.5.1 APPENDIX 2The Reality of Adult Learners OnlineI was slightly concerned about the pupils and the deficiency of personal attending they would be having through my on-line class. Since I did non cognize them, I did n't cognize their learning manners or cultural differences. Adult scholars in peculiar have different acquisition manners and cultural backgrounds, and they may experience they are being left out of larning activities ( Baloglu, 2007 ) . Therefore, distance acquisition may do a psychological, every bit good as a physical, spread ( Durrington, Berryhill, & A ; Swafford, 2006 ) . Students may experience lonely, and a deficiency of face-to-face communicating and competition can impact their motive. Barriers for grownup scholars are categorized as situational, institutional, and dispositional. A individual ‘s fortunes in life at any given clip are considered possible situational barriers. Different policies and patterns may do class engagement more hard are considered institutional barriers. Students ‘ attitudes about their ain abilities to win are considered dispositional barriers. These barriers present extra obstructions for grownup scholars who attempt to obtain an advanced grade ( Spellman, 2007 ) . I found these grownup scholars, who were instructors, to be motivated and really seasonably in turning in their assignments and posting on Blackboard. Having them complete assignments that benefited their theses made them even more enthusiastic about finishing the work. They all asked inquiries and sought elucidation about things they did n't understand. They besides did an first-class occupation noticing on the other pupils ‘ stations. By the terminal of the class, I could see a definite betterment in the content of their article ratings. I think they were larning from one another. The grownup scholars I taught were clearly autonomous and able to be independent. They had life cognition and were goal-oriented. It seems they wanted to see the relevancy and application of their instruction, were practical, needful regard, needed feedback, and had to be interested in the capable affair ( Council for Adult and Experiential Learning, 2000 ; Henick, 1994 ) . The grounds adult scholars obtain a post-secondary grade tend to differ from those of traditional pupils. Adult scholars typically want to progress in an organisation. An extra grade besides makes them more marketable and competitory in the occupation market and allows them to alter callings ( Milheim, 2005 ) .

Comparing The Lottery and Hills Like White Elephants...

Comparing â€Å"The Lottery† and â€Å"Hills Like White Elephants† â€Å"The Lottery† written by Shirley Jackson is a story based off of its point of view, the story would not be told or understood in the same way if it was written in a different point of view. This story keeps the interest of its readers because it has a point of view where only the people in the story know whats going to happen and know more information than the readers do. If this story was written in first person the readers would know what the lottery was from the beginning of the story and that would make the story not have the surprise ending that confuses the audience. â€Å"Hills Like White Elephants† written by Ernest Hemingway is also written in third person point of view.†¦show more content†¦If either of these stories were written in first person point of view the entire plot and conflict of the story would change and the audience would have a different outlook on th e overall story. In â€Å"The Lottery†, if the audience would have known it was a negative lottery it would have changed the effect the ending had on the audience. However, â€Å"Hills Like White Elephants†, would have more of an effect on the audience if it was written in first person point of view. This way the audience would be able to know the main conflict the couple is arguing about throughout the entire story, but the conclusion of the story would change the effect on the readers. Although both stories are wrote in the same point of view, each author interrupts their own personal effects to the stories in which they wrote. Jackson gives her audience clues and hints about the ending, such as the boys piling rocks in the corner of the room, that could be the first signs that the lottery was not what the audience expected it to be. Hemingway however does not take the same approach that Jackson did and did not give his readers clues in the actual text about the info rmation that is being with held from them. The titles of these two stories differ as well, â€Å"The Lottery† is a basic title for the overall story plot, but â€Å"Hills Like White Elephants† is a more complicated title that does not give a general over view of the story. The title is supposed to indicate important informationShow MoreRelatedSummary Of Hills Like White Elephants 909 Words   |  4 Pages2015 Essay Responses to Short Stories Discuss possible symbolic representations in â€Å"Hills Like White Elephants†? In the story â€Å"Hills Like White Elephants† the white elephant symbolizes a negative thing. No person would want anything to do with this. For example, the girl’s unborn child. In the beginning of the story the girl made a comment, and she said that the surrounding hills resemble white elephants. You may think the comment wasn’t unusual, but it really leads towards her talking aboutRead MoreLogical Reasoning189930 Words   |  760 PagesCalifornia USA in 1993 with ISBN number 0-534-17688-7. When Wadsworth decided no longer to print the book, they returned their publishing rights to the original author, Bradley Dowden. The current version has been significantly revised. If you would like to suggest changes to the text, the author would appreciate your writing to him at dowden@csus.edu. iv Praise Comments on the earlier 1993 edition, published by Wadsworth Publishing Company, which is owned by Cengage Learning: There isRead MoreStephen P. Robbins Timothy A. Judge (2011) Organizational Behaviour 15th Edition New Jersey: Prentice Hall393164 Words   |  1573 PagesLoyalty Is an Outdated Concept 87 Questions for Review 88 Experiential Exercise What Factors Are Most Important to Your Job Satisfaction? 89 Ethical Dilemma Bounty Hunters 89 Case Incident 1 Long Hours, Hundreds of E-Mails, and No Sleep: Does This Sound Like a Satisfying Job? 90 Case Incident 2 Crafting a Better Job 91 4 Emotions and Moods 97 What Are Emotions and Moods? 98 The Basic Emotions 100 †¢ The Basic Moods: Positive and Negative Affect 100 †¢ The Function of Emotions 102 †¢ Sources ofRead MoreStrategic Marketing Management337596 Words   |  1351 PagesHallam University and Visiting Professor, Northumbria University AMSTERDAM †¢ BOSTON †¢ HEIDELBERG †¢ LONDON †¢ NEW YORK †¢ OXFORD PARIS †¢ SAN DIEGO †¢ SAN FRANCISCO †¢ SINGAPORE †¢ SYDNEY †¢ TOKYO Elsevier Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 200 Wheeler Road, Burlington, MA 01803 First published 1992 Second edition 1997 Reprinted 1998, 1999, 2001, 2003 Third edition 2005 Copyright  © 1992, 1997, 2005, Richard M.S. Wilson and Colin Gilligan. All rights reserved The rightRead MoreMerger and Acquisition: Current Issues115629 Words   |  463 PagesChinese MA: A Look at Lenovo’s Acquisition of IBM PC Margaret Wang 16.1 16.2 16.3 16.4 16.5 Index Introduction History of Lenovo Lenovo’s acquisition of IBM PC After the merger Conclusion 249 249 249 250 253 255 259 Acknowledgments We would like to thank Stephen Rutt, Alexandra Dawe and Lisa von Fircks at Palgrave Macmillan for guiding us through the process. We also thank Keith Povey Editorial Services and his staff for the excellent work in editing this manuscript, and thanks also to a handful

Supermassive Black Holes Galactic Behemoths

Theres a supermassive black hole  at the center of our galaxy. It cant be seen directly through telescopes or with our eyes, but astronomers know its there.  In fact, there are supermassive black holes at the hearts of many galaxies.  How do astronomers know these monsters lurk in the galactic cores? They use a variety of methods to study light as it passes by a black hole and they also study the region around a black hole to understand how it affects nearby clouds of gas, dust, and even stars.  Currently, the supermassive black hole in the Milky Way, called Sagittarius A*, is a fairly quiet one, and astronomers monitor it in many wavelengths of light to understand its actions. Why The Fascination with Black Holes? Black holes are a favorite in science fiction stories and media. Sometimes theyre used as a plot device to enable some kind of  interstellar travel  trick. Or, they get featured in  time travel or some other important element of a story. As fascinating as such tales are, the reality behind these weird behemoths is more intriguing than writers can imagine. What are the facts surrounding supermassive black holes? Is there any science behind the science fiction  depictions of supermassive black holes? Lets find out. What Are Supermassive Black Holes? Generally, supermassive black holes are just what their name says: really, really massive black holes. They measure in the hundreds of thousands of solar masses (one solar mass equals the mass of the Sun) up to billions of solar masses. They possess immense power and wield incredible influence over their galaxies. Gravitational pull of suspected black hole forms a frisbee-like disk of cool gas, at the core of a galaxy. Later Hubble observations another galaxy confirmed the reality of monstrous black holes gravitational sink holes that trap everything, even light. L. Ferrarese (Johns Hopkins University) and NASA Most supermassive black holes exist in the cores of galaxies. That central location allows them to (at least partially) help hold galaxies together. Their gravity is so immense, because of their incredible mass, that even stars hundreds of thousands of light years away are bound in orbit around them and the galaxy cores they inhabit. Black Holes and Their Incredible Densities Whenever astronomers talk about black holes, the main property they use that sets black holes apart other normal objects in the universe is density. This is the amount of stuff packed into the volume of a black hole. The density at the cores of black holes is so high that it essentially becomes infinite. Specifically, the volume (the amount of space a black hole and its hidden mass takes up) approaches zero. That means its little more than a tiny pinpoint in space, but that tiny dot, called a singularity, contains an incredible amount of mass. That makes it incredibly dense. That density is spread out throughout the entire region of the black hole, from the singularity to the event horizon (which is the point where the gravity of the black hole is too strong for anything to resist.   A model of a black hole surrounded by heated ionized) material. This may be what the black hole in the Milky Way looks like. Brandon DeFrise Carter, CC0, Wikimedia.  Ã‚  Ã‚   That sounds as if the interior of the black hole (beyond the event horizon) could be incredibly crushed, with no room. Interestingly, theres a thought experiment that says the average density of supermassive black holes can actually be less than the very air humans breathe. In fact, the greater the mass, the less dense the supermassive black hole is, if one considers the whole volume of the area from the singularity to the event horizon. The mass would be distributed through that region, with more mass at the singularity than in the outskirts.   If thats true, then it would not only be possible to approach a supermassive black hole, one could theoretically fall into a supermassive black hole and survive for quite some time until getting close to the singularity. However, theres one big problem: gravity. Its so strong that anything swooping past the event horizon would be torn apart by the extreme gravitational pull. So much for wormhole travel!   How Do Supermassive Black Holes Form? The formation of supermassive black holes is still one of the mysteries of astrophysics. Normal black holes are the core remnants left behind from the supernova explosion of a massive star. The more massive the star, the more massive the black hole left behind. One could, therefore, assume that supermassive black holes are created from the collapse of a supermassive star. The problem is that few such stars have been detected. Moreover, physics tells us that they shouldnt even exist in the first place. However, they do. The most massive stars are dozens to a hundred times the mass of the Sun. A few rare hypergiants may be up to 300 stellar masses. Still, even these monsters are a far cry from the types of masses that would be needed to create a supermassive black hole. To put it bluntly: a LOT more mass is needed to make a supermassive black hole than is contained in even the most supermassive stars.   The collision of two black holes holes—a tremendously powerful event detected for the first time ever by the Laser Interferometer Gravitational-Wave Observatory, or LIGO—is seen in this still from a computer simulation. LIGO detected gravitational waves, or ripples in space and time generated as the black holes spiraled in toward each other, collided, and merged. This simulation shows how the merger would appear to our eyes if we could somehow travel in a spaceship for a closer look. It was created by solving equations from Albert Einsteins general theory of relativity using the LIGO data. LIGO/CalTech So, if these objects arent created in the traditional fashion of other black holes, where do the  monster black holes come from? The leading idea is that they formed as much-smaller black holes to build big ones. Eventually, the build-up of mass would lead to the creation of a supermassive black hole. That is a hierarchical theory of building a supermassive black hole. There are some problems with that theory because it requires the study of intermediate mass supermassive black holes. They would be the in b between step from smaller black holes to the supermassive monsters. Astronomers are starting to detect more of these and study their particular characteristics to fill in the gaps in the hierarchical theory.   Black Holes, the Big Bang,  and Mergers Another leading theory about the creation of supermassive black holes is that they formed in the first moments following the Big Bang. Of course, not everything is completely understood about the conditions during that time  in order to figure out how black holes played a role and what spurred their formation.   Observations of the known supermassive and intermediate-mass black holes suggest that the merger theory is likely the simplest explanation. Examination of the oldest, most distant and massive supermassive black holes,  quasars specifically, shows there is evidence that  the merger of many galaxies  played a role. When galaxies merge, it appears their black holes do, too.  Mergers play a role in shaping the galaxies we see today, and so it makes sense that their central black holes may come along for the ride and grow along with the galaxies. Interestingly, when those black holes merge, they send out a lot of energy. The action also emits gravitational waves, which astronomers are just now able to measure. If mergers are the answer, then they supply a partial solution to the intermediate black hole problem. In either case, the answer is not clear, yet. Much more work needs to be done to observe and characterize galaxies and their black holes. Science in the Science Fiction Getting back to science fiction and black holes, there are properties that completely bend the mind that writers have used. Stories of faster than light travel, interstellar travel and time travel pervade science fiction novels. There are even theories that black holes are gateways to alternative universes. Two spaceships enter a wormhole in outer space to get to a universe in another part of the galaxy. Corey Ford/Stocktrek Images So is any evidence to support any of these ideas? Actually, yes, although only in very extreme circumstances. The idea of using black holes as wormholes that somehow connect us with the other side of the universe has been around for decades. Its a great and fanciful fantasy that probably wont become reality anytime soon. The possibilities have even been calculated using serious physics and general relativity. So, theoretically, these things could happen, as was shown in the 2014 movie Interstellar. The physicist who worked with the filmmakers came up with some theoretical ideas that supported the film and worked scientifically. However, the technology required is still not available and a variety of special conditions need to be satisfied.  But who knows —  much of the technology that humans use for flight today was also once thought impossible.   Fast Facts Supermassive black holes exist at the hearts of many galaxies, including the Milky Way.Some galaxies, such as the Andromeda Galaxy, may have more than one of these monsters.When galaxies merge, their black holes can merge, too.Supermassive black holes can have up to billions of stellar masses hidden inside.Our own Milky Way has a supermassive black hole called Sagittarius A* Sources Mohon, Lee. â€Å"Supermassive Black Holes Are Outgrowing Their Galaxies.†Ã‚  NASA, NASA, 15 Feb. 2018, www.nasa.gov/mission_pages/chandra/news/supermassive-black-holes-are-outgrowing-their-galaxies.html.Saplakoglu, Yasemin. â€Å"Zeroing In on How Supermassive Black Holes Formed.†Ã‚  Scientific American, 29 Sept. 2017, www.scientificamerican.com/article/zeroing-in-on-how-supermassive-black-holes-formed1/.â€Å"Supermassive Black Hole | COSMOS.†Ã‚  Centre for Astrophysics and Supercomputing, astronomy.swin.edu.au/cosmos/s/supermassive black hole. Edited and updated by Carolyn Collins Petersen.