Low Voltage Scanning Electron Microscopy Research Paper

Low Voltage Scanning Electron Microscopy - Research Paper Example Working Principles of Scanning Electron Microscopy (SEM) Scanning electron microscopes (SEMs) are microscopes, which produce sample images by scanning the samples using a beam of focused electrons. The focused beam of electrons interacts with electrons within the sample to produce differing signal strengths that can be detected by a secondary electron detector. The focused electrons hit the sample surface, where they either get reflected as back-scattered electrons (BSE) due to inelastic scattering or cause an emission of electrons from the sample surface as secondary electrons (SE) due to elastic scattering (Lyman, 1990). The SE are emitted from the k-orbitals of the sample once the electrons in the beam hit them in a strong enough way that displaces them from the orbital. Both BSE and SE show different properties of the sample material, which commonly includes composition and topography (Boyes, 2000). The focused beam of electrons is scanned by raster scanning and position of the b eam is combined with the signal from the BSE and SE to develop an image. This type of microscopic observation can attain resolutions that are better than a nanometer. The focused beam used in SEM is produced by thermionic means from an electron gun consisting of a cathode made of tungsten. Tungsten is preferable because of its relatively lower vapor pressure and high melting point. Additionally, it is cost-effective because it is relatively cheap. The produced beam passes through two lenses that focus it onto the specimen. The energy of the beam ranges from 0.2 keV to 40 keV depending on the design of the microscope. The focus offers a spot diameter of approximately 0.4 nanometers to 5 nanometers (Joy & Carolyn, 1996). On reaching the final lenses in the column the beam is deflected by a pair of deflecting plates, which deflect it in two planes (X, Y planes) so as to create a raster scan area that is rectangular over the sample’s surface (Asmar et al., 2004). The interaction of beam electrons and the sample make the electrons lose energy through repeated random scattering, which occurs near the surface or much deeper depending on the projection energy in keV. This interaction volume from which energy is released in form of electrons to create the image is known as the interaction volume. The interaction volume is determined by the landing energy of the electrons from the projected beam as well as density and atomic number of the material under observation as the sample. Technically, the differences between HVEM and LVEM are a result of differences in landing energy determined by the electron accelerating voltage. The acquired signals are detected and amplified to develop images. The differences of detected signals are represented by variations in brightness on the visual display. The resultant image is thus a representative of electron energy emitted from the sample’s surface through inelastic and elastic scattering. The Unique Nature of Low volt age scanning electron microscopy (LVSEM) According to Joy and Carolyn (1996), even prior to practical use of scanning electron microscopes, it had been recognized that scanning at low electron accelerating voltage (

Opinion of reading for Journalism class Assignment

Opinion of reading for Journalism class - Assignment Example It is their job to present facts and that only – of course, having put to mind the ability of knowing the limit of what must be presented or not. During the early parts of the second half of the twentieth century, the media allegedly had not been able to do its rightful job. Disputes between the â€Å"black† and the â€Å"white† Americans were told to be [worsened] by the way the media had presented it to the public. With already prejudiced opinions about the â€Å"blacks,† they – as the Kerner Report found out – â€Å"have failed to communicate† the truth. A breach of confidence over knowing what was true – or not – had evolved. Today’s situation, fortunately, is unlike the past. Although there are still issues between the conflicting â€Å"colors† in America in the present, having elected a â€Å"black† president must now prove that the â€Å"white† Americans have accepted that there is [really] no race superior than the other; and with their ability to influence the public’s idea about something, the media must take serious steps toward realizing that with their â€Å"almost-unlimited† right to free expression, considering the civil right of a person, a society or an organization is one essential idea that must not be put

Charles Messier's Butterfly Cluster Essay Example | Topics and Well Written Essays - 1250 words

Charles Messier's Butterfly Cluster - Essay Example He actually searched for comets and to avoid confusion between comets and Messier objects, he and his colleagues compiled them in a list in 1771. It was a remarkable achievement. The list is known as the Messier Catalog or Messier Object List. The list contains a total of 110 objects. The list contains nebulae, galaxies and star clusters. Body During the process of these observations, the first object they observed was the Crab Nebula (M1). A total of 103 objects were listed by Messier and his colleagues (Burnham 73). The Crab Nebula is a ball of gas left over from a supernova explosion. M2 is a globular cluster of stars in Aquarius, M3 is located in Canes Venatici, and Messier 4 to Messier 7 are located in the constellation of Scorpius. The Butterfly Cluster is Messier 6. This object can be seen by telescope clearly, and in the grayish color by naked eye. The Butterfly Cluster existence was first noticed by Giovanni Battista Hoderna in 1654. Ptolemy discovered it while he was observ ing M7, and declared it as a part of M7. After that, Phillips Loys de Cheseaux (1945-1946) observed it and recognized it as â€Å"a very fine star cluster.† And finally it was catalogued by Charles Messier in 1764 in the list of Messier objects (The Griffith Observer 259). The Butterfly Cluster is an open cluster of stars in the constellation of Scorpius known as Messier 6 or the Butterfly Cluster as it resembles a flying butterfly with open wings and antennae. The stars of the cluster twinkle, and it looks very beautiful in the sky. It is visually a very rewarding object; the butterfly pattern is very visible and obvious. It has been placed in the 6th position in the list of Messier objects. Scorpio is located in the Milky Way and contains many massive objects other than M6 and Messier 7. The Butterfly Cluster has a magnitude of 4.2, an angular diameter of 25 arc minutes, and lies at a distance of 1,600 light years with a luminosity of 8,300 suns. The Butterfly Cluster is ab out 50 million years old and can be seen in summer nights clearly with binoculars. The objects (M6 and M7) are the summer’s finest and brightest clusters. Different astronomers have different opinions about M6’s age. According to Burnham, it is 100 million years old; WEBDA estimates its age to be around 95 million years, and 51 million years according to the Sky Catalogue 2000.0. Messier objects of the â€Å"Messier Summer Chart† are clearly visible on summer nights. Messier objects help astronomers to adjust the distance scale of the universe. The above image shows the view of M6 (outcropped). The image was taken through the Astrograph, Takahashi E-180. How Can It Be Seen? It can be seen about 3/ 1-2 degrees northwest of M7 which is located near the tail of Scorpius. It appears as a hazy patch in the dark sky but it should not be confused with Messier 7. Messier 7 is brighter than Messier 6. M7 is seen in between and the Butterfly Cluster is on its lower side. Messier 6 contains many other Messier objects such as M21, M23, NGC 6167, and NGC 6193. Its magnitude is fainter than M7, and fills the field of 25 angular diameter. One of the ways to find the Butterfly Cluster is to identify the two well-known asterisms of Scorpios and Sagittarius. It has two irregular loops of blue and white stars on both wings and at 40-50x, it has three bright stars in the butterfly’s body. The Butterfly Cluster contains almost 80 stars (Plotner 400) with B type blue (hottest) and K type orange stars (BM Scorpii, HD 160371). The brightest K type orange star is a semi-regular

Reflection on research interview schedule Essay Example | Topics and Well Written Essays - 750 words

Reflection on research interview schedule - Essay Example I felt comfortable dealing with a semi-structured interview because it gives one freedom to modify questions to suit different contexts. In a structured interview, all respondents are strictly asked the same questions. Structured interviews are convenient when researching on highly professional research topics. The Gibbs reflection model was utilized to reflect on the interview (Van Audenhove, 2007). The research topic seemed to be very specific. The target population was limited to students pursuing the health promotion top-up degree. Proper preparation and implementation were essential for the successful conduction of this interview. Developing a good interview schedule was the main challenge. An appropriate manner was used in conducting the interview. Proper implementation of the interview was key to making the respondents comfortable. The use of prompts like ‘tell me more’ helped rip more information from the respondents. Interviewers projected a warm, kind and easy to talk to the character to the interviewees. Creating a conducive environment to conduct the interview contributed to the successful conduction of this interview (Seidman, 2012).   Creating the overall questions is the first step in designing an interview. The interviewer should ask him/herself, why am I doing this research? What are the students’ experiences on the health promotion top up degree? Then list the questions that cover the topic of study. After choosing the relevant questions, the interviewer can finally select an appropriate question format. When choosing a question format, it is important to ask open questions first. Starting an interview with personal questions can make the respondent feel uncomfortable and nervous. This way the respondent will not give accurate information (Carter and Mankoff, 2005). The results in terms of information derived from the respondents were

How self-concept, perception, and emotion impact interpersonal Essay

How self-concept, perception, and emotion impact interpersonal communication - Essay Example a brief overview of the theories that are relevant in interpersonal communication, analyze how these theories are relevant in producing effective interpersonal communication, and how interpersonal communication as a process can be manipulated to produce better communication outcomes. Interpersonal communication is the process of interacting between two different individuals, which can be done either face-to-face or through other forms of mediation. It can be studied in four different perspectives: relational or qualitative; situational or contextual; quantitative; and functional or strategic. In the relational perspective, interpersonal communication is seen as a shared process between the sender and the receiver. There is simultaneous interaction between the sender and the receiver, with the aim of creating meaning. In the situational or contextual perspective, interpersonal communication is viewed as part of the specific context to which the sender and the receiver belong. The quantitative perspective is unique from the other perspectives in that it also encompasses not only dyadic interactions as is but also impersonal communication. Functional or strategic perspective emphasizes interpersonal communication as a process to achieve a certain purpose, particula rly, to achieve interpersonal goals (Honors, 2001). Interpersonal communication has four basic elements: the sender—the person from whom the message comes from; the message—the information being sent by the sender to the receiver; the receiver—the person to whom the message is being sent to from the sender; and the feedback or the response of the receiver to the message sent by the sender. Emotion is a complex concept that refers to the mental state that provokes a physiological response, positive or negative (Emotion, 2003). It is differentiated from feeling in that emotions are physiological responses and does not arise from any conscious effort. Theories on Interpersonal Communication usually

Applied Theory of Economics Essay Example | Topics and Well Written Essays - 1000 words

Applied Theory of Economics - Essay Example China and India have progressed exponentially, with current estimates clearly showing how they would be the worlds biggest economies in sheer volume by 2050.Countries like South Korea, Taiwan & Singapore, once minor shipping ports are now among the economic elites of the world, on par with any developed nation today. These spectacular developments have been due to the great flexibility the capitalist system has demonstrated in granting everyone a stake in this brave new world. But with all that being said it also has a dark side attached to it as well. Poor nations with poor legislation on labor rights, wages, health & safety, poor government monitoring and manipulation by many rogue corporations over the ages have put into question the humanitarian aspect of trade. Arguing that corporations shifting production capacities elsewhere are susceptible to exploit the labor and other available resources of their host countries. In my humble opinion ,with the exception of a few highly publi cized cases, the net result of free trade for the developing world has been beneficial .It has alleviated poverty on national levels, led to transfer of modes of technology & made the world more cosmopolitan and integrated . Below are some of the arguments that in my opinion reflect very favorably on the effect of free trade on the developing world. Free trade is not just an economic practice it's a way of life, a political philosophy. "A major source of objection to a free economy is precisely that it [...] gives people what they want instead of what a particular group thinks they ought to want." (Friedman, n.p.) Below are in my opinion some points that argue favorably in the case of free trade for the developing world. Free Trades Alleviates Poverty More cannot be said of free trades vitality in increasing the fortunes of developing world. With the every specific shift of a production capacity in that particular or municipality a steady stream of labor is required. By gaining employments workers get means for their livelihoods and purchasing power. The cumulative effect is on a national scale. One can look no further than the birth of middle class in China & India. They alone have been a major factor in stimulating their local economies with their spending patterns. Free Trade Removes Likeliness of War it's no secret that all commerce flourishes in peaceful times. Especially in this integrated world when there are vested interests in another countries well being. Although the incidence of war hasn't been totally eliminated, by and large majority of the world the developing world has enjoyed prosperity over the decades. In fact, so many nations have entered into regional pacts to gain access to each others markets, to remove import quotas & for freer flow of resources in between their borders. All of these points which are the cornerstone of the Free Trade phenomenon. And in turn Organizations geared towards the free market ideal such as NAFTA (North American Free Trade Organization), EU (European Union) & WTO (World Trade Organization) have shown resounding success since the time of their

Bio-ethical debate Research Paper Example | Topics and Well Written Essays - 1500 words

Bio-ethical debate - Research Paper Example ern is that the very nature of the traditional family is in danger of evolving in a strange, unknown and undesirable direction and that the cloning of animals puts society on the slippery ethical slope towards human cloning. Advocates of cloning practices say that it may, among other things, serve society as an effective alternative treatment for infertility. Cloning is the creation of an embryo by the method of human somatic cell nuclear transfer. This procedure involves implanting DNA cells from an organism into an egg whose DNA nucleus has been removed then chemically treated so that the egg begins to behave as though fertilization has occurred. This results in the creation of embryonic growth of another organism that contains the complete genetic code of the original organism. Through this process, the cloning of mammals has resulted in, to date, hundreds of cloned organisms born. In some of these contexts, cloning refers to established technologies that have been part of agricultural practice for a very long time and currently form an important part of the foundations of modern biological research† (Nussbaum & Sunstein, 1998, p. 1). Though this process has produced many live successes, it has proved considerably less likely to produce successful pregnancies than those conceived through sexual reproduction. In addition, the maj ority of cloned animals have experienced some type of birth defect. Replication of an organism’s DNA identity does not occur naturally within mammals; only plants produce offspring through replication from one generation to the next. â€Å"The prospect of such replication for humans has resulted in the most controversial debate about reproduction ever to be taken up in western civilization† (McGee, 2001). Research regarding the cloning of animals may supply data that will be useful in the biotechnological and medical sciences. Some of the goals of this research are: â€Å"to generate groups of genetically identical animals for