Note: Sample below may appear distorted but all corresponding word document files contain proper formattingExcerpt from Term Paper:
Surface irregularities are often seen when using the scanning electron microscope, but these are absent using the AFM. One such analysis is described below:
Occasionally, the cartilage surface exhibits local discontinuities where an underlying fibrous network is distinguishable. Digestion of the cartilage surface with chondroitinase AC exposes this fibrous network more systematically so that the individual fibers are visualized with great clarity by AFM. When imaged at higher magnification, these distinct fibers exhibit a 60nm repeat, indicating that they are assembled from collagen fibrils. (Miller, Aebi, and Engel para. 4)
The AFM has been shown to be valuable in similar analyses of biological materials and processes. While AFM images also offer a view of the atomic detail of solids, the process is not useful for analyzing biomolecules such as proteins because they are designed to undergo conformational changes and form flexible supermolecular assemblies, meaning they are mechanically "soft" so that the surface cannot be probed for atomic detail. However, as Miller, Aebi, and Engel note, "state-of-the-art specimen preparation and instrumentation now allow the surface topography of native proteins to be imaged at subnanometer resolution" (para. 5).
A recent example of biological research using the AFM comes from Santa Barbara, California, where researchers used the AFM to discern unique properties of bone:
Collagen, the most abundant protein in the human body -- serving as a structural component of a variety of tissues including bone, tendon and skin -- reveals special properties which allow it to "bounce back" when pulled or stressed in laboratory experiments. The AFM operates by tapping and pulling with a tiny needle. ("Bone Strength Probed by Scientists" para. 1)
This research shows that the collagen in bone contains sacrificial bonds that rupture as the collagen is stretched, and these ruptures then heal. The purpose of these bonds is to provide a means for dissipating mechanical energy in collagen molecules (("Bone Strength Probed by Scientists" para. 2).
AFMs constitute a subset within the larger group known as scanning-probe microscopes, which can utilize many different types of tips to measure electrical, mechanical, or magnetic properties. Tips exist that can perform simultaneous dimensional and electrical measurements. It is when a scanning-probe microscope uses a tip that can discern properties at the atomic level that the instrument becomes an atomic-force microscope. Such devices can measure features within a few Angstroms and do so without harming the sample. As on scientist notes, "Manufacturers need to perform nondestructive measurements in all three dimensions to ensure their device geometries fall within ever-smaller tolerances" (Titus para. 4). Another company uses AFM to detect flaws in surface-acoustic-wave devices, defects that cannot be seen with an optical microscope. The same company uses AFM to check the results of steps in photolithograpy (Titus paras 5-6).
Kevin Kjoller considers how to measure the true resolving power of an atomic force microscope, noting first that resolution means the same as it does for an optical microscope, meaning the minimum distance between two adjacent objects that a microscope can identify as separate. Kjoller complains that most manufacturers substitute some meaningless term for resolution and ignore the reality. Several issues need to be considered, such as the size of the probe and three types of limiting noise, electical, mechanical, and acoustic. Kjoller defines electtical noise as "the sum of the thermal and operating noise from all components inside the AFM electronics, including any noise due to cross-talk and less-than-optimal grouping" (Kjoller para. 7). Mechanical noise can be particularly harmful and may derive from the mechanical path length between the probe and the sample. Acoustic noise means that the system generates noise, and this can be eliminated with a well-designed and well-implemented acoustic isolation environment" (Kjoller paras. 8-9).
The accuracy of the AFM depends on the state of the tip, and a worn tip can produce blurred images ("V-shaped Tips Blur Microscopy" paras. 1-7). Efforts to control for this include the recent development of an automatic tip evaluation system showing when the tip needs to be replaced ("Automatic Tip Evaluation Broadens AFM Applications" para. 1).
More and more applications for the AFM are developed all the time. Scientists have found many ways to make use of the unique capabilities of this system to analyze different substances down to the atomic level.
Automatic Tip Evaluation Broadens AFM Applications." R & D (1 July 1998). September 15, 2005. http://www.highbeam.com/library/doc3.asp?DOCID=1G1:21007984&num=31&ctrlInfo=Round17%3AProd%3ASR%3AResult&ao=&FreePremium=BOTH.
Atomic Force Microscopy." 2005. September 16, 2005. www.swan.ac.uk/chemeng/afm.htm.
Ball, Philip. Molecules. Oxford: Oxford University Press, 2003.
Baselt, David. "How AFM Works." Atomic Force Microscopy. 1993. September 16, 2005. http://stm2.nrl.navy.mil/how-afm/how-afm.html#General%20concept.
Bone Strength Probed by Scientists: Atomic Force Microscope Reveals 'Sacrificial Bonds' in Bone Collagen." Ascribe Higher Education News Service (12 Dec 2001).
September 16, 2005. http://www.highbeam.com/library/doc3.asp?DOCID=1G1:80759635&num=27&ctrlInfo=Round17%3AProd%3ASR%3AResult&ao=&FreePremium=BOTH.
Dyson, Freeman J. The Sun, the Genome & the Internet: Tools of Scientific Revolutions. New York: Oxford University Press, 1999.
Hong-Quiang Li. "Introduction." Atomic Force Microscopy Student Module. 1997. September 15, 2005. http://www.chembio.uoguelph.ca/educmat/chm729/afm/introdn.htm.
Kjoller, Kevin. "Judging AFM Performance." R & D (1 Aug 2000). http://www.highbeam.com/library/doc3.asp?DOCID=1G1:65189799&num=24&ctrlInfo=Round17%3AProd%3ASR%3AResult&ao=&FreePremium=BOTH.
Kooyman, Brian P. Understanding Stone Tools and Archaeological Sites. Calgary, Alberta: University of Calgary Press, 2000.
Muller, Daniel J., Ueli Aebi, and Andreas Engel. "Imaging,
Measuring and Manipulating Native Biomolecular Systems with the Atomic Force Microscope." 1996. September 16, 2005. http://www.mih.unibas.ch/Booklet/Booklet96/Chapter3/Chapter3.html.
Perez-Murano, Francesc. "Nanolithography of PMMA Using Atomic Force Microscopy." (4 July 2005). September 16, 2005. http://nanotechweb.org/articles/journal/4/7/1/1.
Ravenoff, Ruth. "Portrait of a Genome." Art Journal, 55(1)(1996), 37.
Titus, Jon. "AFMs Pinpoint Surface Defects: When Optical Inspection Fails to Uncover Defects, You Can Turn to an Atomic Force Microscope to Scan a Sample's Surface." Test & Measurement World (2004, March 1). September 17, 2005. http://www.highbeam.com/library/doc3.asp?DOCID=1G1:118793765&num=2&ctrlInfo=Round17%3AProd%3ASR%3AResult&ao=&FreePremium=BOTH.
Uldrich, Jack. "Why Nanotechnology Will Arrive Sooner Than Expected." The Futurist.36(2)(March-April 2002). September 16, 2005. http://www.questia.com/PM.qst?a=o&d=5000698146.
V-shaped Tips Blur Microscopy." Chemistry and Industry (17 March 2003). September 15, 2005. http://www.highbeam.com/library/doc3.asp?DOCID=1G1:99773234&num=37&ctrlInfo=Round17%3AProd%3ASR%3AResult&ao=&FreePremium=BOTH.
What is an Atomic Force Microscope?" The University of Toledo College of Engineering (2005). September 16, 2005. http://www.che.utoledo.edu/nadarajah/webpages/whatsafm.html.[continue]
"Atomic Force Microscope Operates At" (2005, September 18) Retrieved December 7, 2016, from http://www.paperdue.com/essay/atomic-force-microscope-operates-at-67140
"Atomic Force Microscope Operates At" 18 September 2005. Web.7 December. 2016. <http://www.paperdue.com/essay/atomic-force-microscope-operates-at-67140>
"Atomic Force Microscope Operates At", 18 September 2005, Accessed.7 December. 2016, http://www.paperdue.com/essay/atomic-force-microscope-operates-at-67140
From a materials development perspective, this is the important part: "The significance of this advance is this: if a material as expensive and rare as a diamond can be turned into a 'commodity,' then the applications of a variety of other materials, including everything from copper and ceramics to steel, can also be improved and utilized in different ways" (Uldrich, 2006, p. 17). From a pragmatic perspective, these developments
Feynman (MLA Citation) Plenty Room at Bottom There's Plenty of Room at the Bottom At the dawn of the 1960's the world was entering a new age of great technological advancements which Richard P. Feynman discussed in a speech that has been immortalized in print ever since. In "There's Plenty of Room at the Bottom," Feynman, a physicist, discussed a simple question, how small can one go? In other words, he pondered the
Technology Evolution Many of the electric gadgets we use today like the cell phones and the home computers were invented in the 80s. Many multinational corporations came into existence in the 80s this spur the growth to a record 3.2% per year (Bellis, 2012). This was the highest nine-year rate in American history. This was occasioned by a number of factors some of which were economic, financial, legislative, and regulatory frameworks.
Nanomachines The Science of molecular size machines and its engineering designs and constructions until late 1980s were not considered practicable. Nanotechnology, according to the leading exponents of that time were neither feasible nor viable, due to the fact of total structural difference of the constituent of nano-molecular device i.e. Atoms from the mechanical objects of every day life. The essential components of engineering mechanics i.e. cogwheels, gears or motors could not
So increased voltage results in a drop in current. As the voltage continues to increase the junction begins to function as a normal diode as electrons travel by conduction through the p-n junction and no longer tunnel through it. Therefore the most important region for operation in a tunnel diode is the negative resistance area. Used in reverse direction Esaki diodes are called back diodes and act as very fast
Add to this confusion the growing prevalence of telecommuters and the issues of the FLSA become even more complicated. Of course some telecommuting positions fall into the exempt category, and therefore are not subject to overtime pay, however some do. Due to the freedom to engage in 'private pursuits', employers may monitor when a virtual employee logs onto his or her computer and may require that he or she get