buy custom Scanning Electron Microscopy essay

buy custom Scanning Electron Microscopy essay Scanning Electron Microscopy is a category of the electron microscope, which uses highly focused beams of strong or high-energy electrons in order to generate diverse types of signals on the entire surface of the solid specimens. The high-energy electrons interact actively with the solid specimen atoms thus producing clear signals containing detailed information of the sample such as chemical composition, texture (morphology), orientation of sample materials, electrical conductivity of the sample, and crystalline structure. SEM produces many types of electron signals such as characteristics X-rays, secondary electrons, cathodoluminescence (light), back-scattered (BSE) electrons, transmitted electrons, and specimen current, which result from, active interactions of electrons beams with specimen atoms near or at the sample surface (Joseph Linda 2003). SEM technology, especially the secondary electrons imaging (SEI), is highly effective as it can be able to produce extremely high-resol ution specimen images revealing extremely small details even of size lower than 1 nanometer (nm). In addition, SEM is even capable of analyzing selected points on the sample an approach extremely useful in semi-quantitatively or qualitatively analysis. In order to understand Scanning Electron Microscopy (SEM), its concepts such as the basics of SEM as well as the Structure and Working of SEM are carefully analyzed. The SEM uses focused beams of many electrons to create the specimen image and gain information regarding its composition and structure. The most basic steps involved in the SEM are: A unique stream of strong electrons are produced by the electron guns in the high-vacuum chamber, the stream with positive electrical potentials, is then accelerated towards a solid specimen while being focused and confined using magnetic lenses and metal apertures into a very thin, highly focused, and monochromatic beam. The solid sample is highly irradiated by this beam and interactions quickly occur inside this highly irradiated sample thus affecting the beam of electrons. These effects and unique interactions are detected and quickly transformed into the specimen image. The structure of SEM comprises many parts, which work together, to achieve the overall objectives of this machine. The first and most basic part of SEM structure is the Electron Gun. This part is paramount as it is the only source of the electrons in SEM. In most cases, Electron Gun is a unique v-shaped filament manufactured using tungsten or LAB6 (lanthanum hexaboride) cathodes that are perfectly wreathed with the Wehnelt cap also referred to as Wehnelt electrode (Patrick 2009). The other part of the SEM structure is the condenser lenses. It has two-condenser lenses referred to as first and second condenser lens respectively, which are used to condense the electron beams flowing from the electron gun. In addition, it has deflection coils, which are used to deflect the electron beams flowing from the electron gun. Objective lenses are also found in the SEM structure. In addition, it has electron detectors that are used to detect various types of signals such as X-ray detectors, and B ackscatter electron detectors. It also has a vacuum pump which is used to create a vacuum in the SEM. Vacuum in the specimens chamber creation is crucial because it aids in the only specimens pretreatments necessary for this process which is the metal coating of the specimens. This unique procedure is only done in a complete vacuum evaporator and lasts for approximately 15 minutes. The standard working of SEM is unique and intriguing. A finely and highly-focused beam of electrons scanned across the entire sample surface results in generation of back-scattered electrons, characteristic X-rays, and secondary electrons. These electron signals are thoroughly collected by electron detectors in order to form clear images of the specimen displayed on the screens made of cathode ray tubes (Goldstein, Newbury, Lifshin, 1981). All the features obtained from the SEM images are then analyzed to determine their elemental compositions and other features. Data output in SEM is carefully generated in the real time on the Cathode Ray Tube (CRT) monitor. The spectra and images obtained in the screen scan be easily printed, recorded, or even emailed. Buy custom Scanning Electron Microscopy essay

Profile of Tantalus, Mortal Son of Zeus

Profile of Tantalus, Mortal Son of Zeus Favored by the gods, Tantalus was allowed to dine with them. Taking advantage of this position, he either made a meal for the gods of his son Pelops or he told other mortals the secrets of the gods which he had learned at their table. When Tantalus served Pelops to the gods, all except Demeter recognized the food for what it was and refused to eat, but Demeter, grieving for her lost daughter, was distracted and ate the shoulder. When the gods restored Pelops, he was given an ivory replacement. Consequences Tantalus is known primarily for the punishment he endured. Tantalus is shown in Tartarus in the Underworld eternally trying to do the impossible. On earth, he was punished either by having a stone hang forever over his head or by being driven from his kingdom. Punishment The punishment of Tantalus in Tartarus is to stand knee deep in water but be unable to slake his thirst because whenever he bends down, the water vanishes. Over his head hangs fruit, but whenever he reaches for it, it goes just beyond his reach. From this punishment, Tantalus is familiar to us in the word tantalize. The Family of Origin Zeus was the father of Tantalus and his mother was Pluto, daughter of Himas. Marriage and Children Tantalus was married to a daughter of Atlas, Dione. Their children were Niobe, Broteas, and Pelops. Position Tantalus was king of Sipylos in Asia Minor. Others say he was king of Paphlagonia also in Asia Minor. Sources Ancient sources for Tantalus include Apollodorus, Diodorus Siculus, Euripides, Homer, Hyginus, Antoninus Liberalis, Nonnius, Ovid, Pausanias, Plato, and Plutarch. Tantalus and the House of Atreus After Tantalus betrayed the trust of the gods his family started to suffer. His daughter Niobe was turned to stone. His grandson was the first husband of Clytemnestra and was killed by Agamemnon. Another grandson, through ivory-shouldered Pelops, was Atreus, father of Agamemnon and Menelaus. Atreus and Thyestes were brothers and rivals who wound up destroying each other. They had fallen under a curse uttered by Hermes son Myrtilus against Pelops and all his family. Atreus further defied the gods by promising Artemis a golden lamb and then failing to deliver it. After a series of tricks and treacheries between the brothers, Atreus served up a dish to his brother of three of Thyestes children.

Theology College Essay Example | Topics and Well Written Essays - 1000 words

Theology College - Essay Example It must, thus, be completely disregarded as a possible option. The starting point for any consideration of abortion as a solution to a problematic and unwanted pregnancy must be the acknowledgement of God as both the giver and the taker of life. None can, and none should attempt to usurp this role. Indeed, as Bonhoeffer wrote, Destruction of the embryo in the mother's womb is a violation of the right to live which God has bestowed upon this nascent life. To raise the question whether we are here concerned already with a human being or not is merely to confuse the issue. The simple fact is that God certainly intended to create a human being and that this nascent human being has been deliberately deprived of his life. And that is nothing but murder.1 As a pastor, however, and as briefly touched upon in the preceding, it need be acknowledge that the young girl must be going through a period of guilt, compounded with despair. These two are probably at the heart of her evident, although unexpressed, partiality towards abortion as a solution. ... Had she or her family been in a position to afford the pregnancy and the child, her situation may not be as problematic as it currently is. This is a fact that I cannot ignore and which I should express sympathetic understanding of. Sympathies and personal sentiments aside, however, theological doctrine cannot be altered or tailored to suit our immediate purposes but need be consistently applied and adhered to, irrespective of circumstances. Theological doctrine asserts the right to life. As Bonhoeffer affirms, "God gives before He demands."3 The implication is clear: the right to life predominates over, and precedes the responsibilities of life. The foetus has a right to life and the responsibilities associate with that life are, although of critically important concern, secondary to the affirmed right. Accordingly, rather than be influenced by the economic and social considerations and concerns that the foetus, as a life, will bring with him/her, the primary influence, and the determinant of any decision made with respect to this case, should be the right to life. The right to life, the value of life, is an integral part of Christian theological doctrine and is affirmed through Soteriology, Christ's Physical Resurrection, and Ecclesiastology. The salvic purpose of Christ's death is an affirmation of life and the right to life; the Christ's Physical Resurrection is a testament to the eternal nature of life, on the one hand, and to the value which Christianity places on bodily life; the teachings of the Church, those being the teaching of Jesus Christ and, the Church's mission, that being the affirmation of Christ's teachings and