Group 5 Project - Electron Microsopy

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SEM of Salmonella

Introduction

One of the most important techniques in cell biology – possibly the most important – is microscopy, since the details of cells and their organelles are too small to be seen with the naked eye. Electron microscopes have permitted cell biologists to see cells and cell components with much greater resolution than light microscopes, allowing a much greater understanding of cell structure and function.


How It Works - The Electron Microscope

There are two main types of electron microscope: the Transmission Electron Microscope (TEM) and the Scanning Electron Microscope (SEM), both of which are covered here. Before looking at each individually, a general overview of electron microscopes will be given.


Looking at an electron microscope for the first time, understanding how it works can seem like a daunting task. However, it is easier to grasp the basic concept once one realises that the electron microscope follows the same basic pattern as the light microscope. Consider a typical light microscope. A light microscope:

A transmission electron microscope


1. Has a light source

2. Has a place for the specimen

3. Has lenses to magnify the specimen

4. Displays a magnified image of the specimen[1]


In general, electron microscopes follow the same pattern, but with some differences:


1. A beam of electrons replaces the light source

2. The prepared specimen sits in a vacuum chamber

3. The “lenses” are hoop-like coiled electromagnets that the electron beam passes through

4. The image is displayed on a screen, or as a photograph [2]


A beam of electrons fired from an electron gun is used because a fast-moving electron beam has a much smaller wavelength than light, allowing the electron microscope to have a much higher resolution than the light microscope. Commonly, a tungsten filament is used in the electron gun; a very high voltage (ranging from 50,000 to millions of volts) is passed through the filament, causing electrons to be thrown off. An anode (a positively-charged electrode) is used to accelerate the electron beam, which reduces the wavelength and allows for higher resolution images. [3]


Preparation of specimens is different for transmission and scanning electron microscopy. However, in both transmission and scanning electron microscopy, the electron beam and the specimen must be kept in a vacuum, since electrons can lose their energy to particles in air. Thus, neither TEMs nor SEMs can be used to observe live specimens, as living creatures could not survive the required fixation/preparation process, or being positioned in a vacuum (though there are some exceptions to this rule in the case of SEMs)[4]. [5]


In a light microscope, the lenses concentrate the light into a beam and magnify the image of the specimen by refracting that beam of light. The electromagnetic “lenses” of the electron microscope (coils of wire through which a current of one amp or less is passed) act in a similar way, whereby the magnetic field generated by the lenses bends and focuses the electron beam passing through it. [6]


Finally, the electrons containing information about the specimen are interpreted into an image that can be viewed either as a photograph image or on a cathode-ray TV screen. The way images are formed differs between TEMs and SEMs. [7]


Transmission Electron Microscope

A simplified schematic drawing of a transmission electron microscope

TEMs give us the ability to study the internal structure of cells and organelles. Specimens being prepared for TEMs must be fixed and sliced into very thin sections. Fixation with glutaraldehyde followed by osmium tetroxide (which acts as a fixative and an electron-dense stain) is common in electron microscopy, though there are a range of fixation techniques available, such as fixation with formaldehyde or cryo-fixation – the method of fixation depends on the specimen to be viewed and the view desired. Specimens for electron microscopy must be stained with an electron-dense substance (like lead, osmium or gold) because otherwise the accelerated electron beam can damage the specimen. [8]


A transmission electron micrograph of a human blood cell with internal cell structure visible

Electrons are fired from the electron gun into a vacuum, where the condenser lenses focus the beam of accelerated electrons on the specimen. The electrons interact with and pass through the specimen to reach the objective lens, which produces the first image of the specimen and performs the first focusing and magnification. Next is the intermediate lens which controls magnification of the image, followed by the projector lenses, which project the final image onto an imaging device such as a photographic plate, fluorescent screen or CCD camera. The image is viewed through a leaded window or magnifying binocular eyepieces, or the image is captured by camera and viewed on an external screen. [9]


Areas of the image appearing as bright are less dense, so more electrons were able to pass through, while dark areas indicate dense areas of the specimen where fewer electrons were able to pass through. Images produced by TEMs are two dimensional. TEMs have the highest resolution of any electron microscope, allowing us to see structures 1-2 nanometres in size (1 million times magnification)[10] [11].[12]


Scanning Electron Microscope

A simplifed schematic drawing of a scanning electron microscope

Since SEMs give us an image of the surface of a specimen, preparation of specimens for scanning electron microscopy differs from that of transmission electron microscopy. Larger specimens can be placed in an SEM than can be placed in a TEM (e.g. whole insects) as the beam does not have to pass through the specimen but over it. Specimens must be coated with a metal that reflects electrons, such as gold; this coating of a conductive substance amplifies the electron signal and also prevents the electrons from charging the specimen. [13]


A scanning electron micrograph of the head of a moth

Electrons are fired from the electron gun into the vacuum and accelerated before they pass through one or two condenser lenses that focus the electron beam. The beam then passes through magnetic coils controlled by a scanning generator that direct it in a predetermined scanning motion over the surface of the specimen. As electrons hit the surface of the specimen they bounce off – these are known as secondary electrons. The secondary electrons are detected by an electron collector which is connected to an amplifier, which processes and amplifies the signal before it is sent to a cathode-ray tube screen where the image can be viewed. The scanning generator also scans the electron beam in the cathode ray tube, and allows magnification of the view displayed on the cathode-ray tube screen by reducing the surface area of the specimen being scanned.[14]


SEMs produce very sharp three-dimensional images of the surfaces of specimens; however, the resolution is less than that of TEMs, with maximum resolution being approximately between 3-20 nanometres, depending on the microscope[15] [16].[17]


Comparing the Two

Transmision Electron Microscope Scanning Electron Microscope
Electron beam passes through specimen Electron beam ‘scans’ over specimen
Specimens must be very thin Specimens can be larger
Very high resolution (1 nanometre, or x1,000,000) Resolution not as high as TEM (about 10 nanometres)
Specimens must be dead Specimens must be dead (but some special exceptions)
All images are black and white
Microscopes are large and expensive
A vacuum is required


History

J.J Thompson (1856 - 1940) - Discovery of the Electron

  • In 1897 during a series of experiments that were set up to study the nature of electric discharge in a high-vacuum cathode ray tube, he discovered the electron. [18]
  • Received the Nobel Prize in Physics, 1906

Louis deBroglie (1892 - 1987) - Wavelength of moving electrons

  • Discovered the wave nature of electrons [19]
  • Awarded the Nobel Prize in Physics in 1929 for his work.

Hans Busch - Magnetic or electric fields act as lenses for electrons (1927) [20]

  • Calculated the electron trajectories in an electron ray bundle and found that a magnetic field of the short coil had the same effect on the electron bundle as a convex glass lens has on a light bundle.

Ernst Ruska (1906 - 1988) and the development of the electron microscope [21]

Ernst Ruska
  • In 1929 he submitted his Student Project Thesis on a method of designing a cathode ray oscillograph on the basis of the experimentally found dependence of the writing spot diameter on the position of the concentrating coil.
  • In 1930 he published a paper on the contribution to geometrical electron optics.
  • In 1931 the first blueprints of the electron microscope were put together by Ernst Ruska and Max Knoll
  • Ernst Ruska and Max Knoll published Das Elektronenmikroskop (The electron microscope) in 1932, announcing the development of the electron microscope to the scientific world.
  • started work with Bodo von Borries in 1932, refining the magnetic converging lens of short field lens needed to obtain a better than light resolution.
  • In 1937 along with Bodo von Borries, began collaborating with Siemens to industrially produce the electron microscope.
  • By 1938 two prototypes with a condenser and polepieces for objective and projectinve as well as airlocks for specimens and photoplates had been completed, with a maximum resolution of 30,000x
  • In 1939 the first serially produced electron microscope was delivered to IG Farbenindustrie, a major representative of the chemical industry, at its works in Hoeschst.
  • In 1986 Ernst Ruska was awarded the Nobel Prize in Physics for his work in electron optics and the design of the first electron microscope.

M. Knoll - First Scanning Electron Micrograph [22] [23]

  • In 1935, Knoll used a primitive version of a SEM which contained two cathode ray tubes and produced a micrograph of a solid polycrystalline structure which was a piece of steel.

Manfred von Ardenne - 1938 [24] [25]

  • Made ground-breaking research on the physical properties of the Scanning Electron Microscope and beam specimen interactions.
  • He developed a British patent SEM but it was never made into a working model.

Zworykin et al. - first early form of SE Image - 1942 [26] [27]

  • Developed a sealed- off field emission SEM and produced an primative SEM image. However it did not meet up with the swiftly developing Transmission Electron Microscope and so was considered uneventful and further progress was terminated.

Professor Sir Charles Oatley (1904-1996) and his involvement in the development of the Scanning Electron Microscope [28]

  • In the late 1940s, Oatley, a lecturer in engineering became interested in conducting some research in electron optics and decided to persue the SEM to complement the works of fellow colleague - V. E. Cosslett's work on the TEM.
  • In 1948, with one of his students - Dennis McMullan, built their first SEM. With this microscope they could achieve a resolution of 50nm, and were able to produce the first micrographs showing the striking 3D imaging characteristics of the modern-day SEM
  • In 1952, Oatley began work with another student, Ken Smith. Together they continued to make improvements to the electron optical system and increase the efficiency of secondary electron collection. In 1955 they published 'The Scanning Electron Microscope its Fields of Application', which outlined the uses of the SEM.
  • A third research student, O. C. Wells started work with Oatley in 1953. He developed the second SEM which had many improvements on the original SEM. These improvements made the SEM better for experimental work and the configuration was used in all subsequent SEMs.
  • His fourth student, Everhart who started in 1955, worked with Oatley and together they worked on tweaking the SEM to make it more efficient and improve the quality of the images produced.
  • With his fifth student Peter Spreadbury in 1956, they built a simple SEM which utilised CRT as a display unit.
  • Between 1956 and 1960, Oatley supervised a number of other students who further improved the SEM, such as applying ion beam optics, adding a magnetic objective lens which improved resolution, modifying the SEM built by Wells to enable the examination of thermionic emitters at temperatures exceeding 1000K and achieving a resolution of 10nm.
  • The first commercial SEM was developed in the early 1960's.

Current and Future Uses

The electron microscope has many applications unique to itself as it has a stronger magnification power than light microscopy. This allows a better understanding of the phenomenon that occur out of the range of other viewing devices.

Current Applications

Some examples of the current uses of EM include:

Studies of cells providing discoveries in:

  • Cell Morphology and Ultrastructure
EM provides information about surface structures giving insight to the relationship with internal structure, as well as allowing identification of cells based on their surface morphology.[29]. The ultrastructural detail obtained by findings can be applied to for a better understanding of cellular functions and the processes associated. With the use of the TEM, Morinaga et al (2009) were able to show osseointegration does not take place at the surface of bone or the titanium implants, and thus an altered understanding of ultrastructural development of lamellar bone in relation to titanium implants over time [30].
  • Cell-Cell Communication
With the use of electron micrographs we are able to see the arrangement of gap junctions, which facilitate cell-cell communication. The connexins can be seen to take a hexagonal shape and allow small molecules to pass through [31]. Such understanding of gap junctions is only possible by knowing their structure from EM.
  • Phagocytosis
EM helps to display the importance of phagocytosis for the body’s reaction to foreign particles. From the micrographs in Berry and Galle's article (1980), it is clear that the alveolar pneumocytes have phagocytosed glass and clay in an attempt to eliminate the particles from the airways [32]. With the application of the EM, we are able to gain a better understanding of human phagocytes. From EM images, hypotheses have been made about other cellular components that may be invoved in the phagocytic process, for example dense filaments for transports of vacuoles [33], providing leads for further research.
  • Distribution of Ribosomes, Parasites or Proteins in Ultrathin Sections of Cell Tissue
Using TEM, RNA probes and cell hybridisation concurrently, we are able to display the distribution of ribosomes, nucleii, mitochondria, parasites [34] and proteins across a tissue, the sites at which genes are expressed [35], and the effects that viruses have on components [36]. This is important when locating and identifying a desired subject, gaining insight about its origin and effects, and also when verifying results from other methods, such as light microscopy, by comparing consistencies.
  • Strucural Information of Organelles
As electron microscopy improves, so does our knowledge of all cells including their cellular components. Where previous researchers have made assumptions on the indefinite, current researchers can analyse based on EM findings. Often the structure of mitochondria was presented as uniform yet recent research has shown that it is highly variable and that "cristae conformation is a direct consequence of the specialized function of the respective tissue." [37]. This explains the variety of structures of the mitochondria across a range of tissue types. Structures of Golgi Apparatuses have also been shown to differ greatly in different tissues, from small stacks, to large cylindrical shapes [38]. In 1984, Barnes and Blackmore clarified perceptions of the chloroplast, confirming a sharply defined envelope which connected to the inner membranous system in places, and were able to deduce exact sizes of the organelles as well [39].


Electron micrograph of a negatively stained human papilloma virus which occurs in human warts

Virus Identification

In 1947, electron microscopy was used to distinguish chickenpox from smallpox as they sizes of the cells are smaller and sparse[40]. The detail acquired of such small particles and their structures, makes it possible to differentiate a wide variety of contagious agents. One downfall of the electron microscope for detecting viruses is that the images can be ambiguous, and thus the analyst must find multiple cells of the same morphology before identifying the virus and initial photographs must be kept to verify the identification[41].


Environmental Forensic Microscopy Investigations

In environmental forensic investigations, EM as applied to assess hygiene and monitor the environment providing information about contaminants that are present. Dust, lead and asbestos particles, hairs, fibers and mineral grains are analysed by EM and may be can be connected to causes of poor hygeine and can also be used as evidence in criminal cases, linking suspects to crime scenes [42].


Semiconductors Analysis

TEM is highly useful in the semiconductor industry for obtaining precise measurements of devices (nanometrology) and the analysis of faults that develop when manufactured (failure analysis). The semiconductors are so small that such detail can only be acquired by EM. The devices are evaluated, providing feedback about certain materials used, the effectiveness of the semiconductor and a failure analysis.[43].


Materials and Chemical Research

The application of TEM to materials research, such as crystallography, presents feedback that allows for improvements in the composition of a substance and analysis of the behaviour of a material in a given situation [44], particularly nanosized materials.


Cryo-electron microscopy

This procedure was developed as the existing fixation techniques lead to altered structures of some specimens due to varied levels of dehydration. The alternative fixation was freezing the hydrated specimens. This made it possible to view a fully hydrated subject, without separation from the vacuum chamber, which greatly reduces the resolution [45] [46]. Cryo-electron microscopy is particularly effective for structures that only exist under the forces of liquid water, and thus cant be viewed in a dehydrated form [47].

Future Applications

Apart from developing applications that are currently in use, there are some areas where little research has been undertaken, and thus a greater focus in these areas may lead to future uses.

Fixation


Diagnosis of cancer

A breast cancer cell seen through an electron microscope

Where the use of routine techniques, such as light microscopy, may lead to an incorrect diagnosis of a difficult tumour, the additional ultrastructural detail obtained from EM would increase the likelihood of an accurate diagnosis. Cell-cell communication between malignant and normal cells could be monitored, as well as the location of cancerous cells via immunogold labeling. Although there is not much research in this area appears to be promising in the future, as it could prove to be more cost effective than current procedures. [48]


Rapid detection of infectious agents

EM must remain as one of the primary tools of rapid diagnostic virology, as it can be used to identify unexpected agents quickly such that they can be treated. An example of this is quick response and identification of B. anthracis in the biological terrorist letter attack on the U.S. [49].


Environmental Scanning Electron Microscopy (ESEM)

This electron microscope does not require a vacuum and can be operated at warmer temperatures, allowing more similar conditions to the specimen's normal environment. This would offer a greater insight into specimens and their functions [50][51].

Uses At UNSW

The University of New South Wales has its' own Electron Microscope Unit (UNSW Analytical Centre, 2010). It is located in the Basement of the Chemical Science Building on the main campus.

In The EMU, there are two TEMs and five SEMs available to use, all of which are used for a different type of analysis. They also have a variety of equipment that are used for the preparation of both organic and inorganic specimens as well as equipment that prepare specimens for use in SEM and TEM examinations.

The EMU is used for research services, training and programs. It provides microscopy services to researchers from the UNSW community as well as other universities and other research bodies. The EMU is used in the collection of data for over 300 peer-reviewed papers per year. This unit educates researchers and academics through seminars, training courses and workshops as well as hands on practical experience.[52]

To access the EMU at UNSW web site click on the link: | EMU at UNSW

References

  1. Woodford, Chris. (2009) How Electron Microscopes Work Explain That Stuff. Accessed 21/4/2010 <http://www.explainthatstuff.com/electronmicroscopes.html>
  2. Woodford, Chris. (2009) How Electron Microscopes Work Explain That Stuff. Accessed 21/4/2010 <http://www.explainthatstuff.com/electronmicroscopes.html>
  3. Hunter, Elaine. (1993) Practical Electron Microscopy: A Beginner's Illustrated Guide (2nd ed.) New York and Oakleigh: Cambridge University Press. pp 114-115. isbn= 0-521-38539-3
  4. Hunter, Elaine. (1993) Practical Electron Microscopy: A Beginner's Illustrated Guide (2nd ed.) New York and Oakleigh: Cambridge University Press. p 107. isbn= 0-521-38539-3
  5. Nixon, W.C (1971). The General Principles of Scanning Electron Microscopy in Huxley, H.E and Klug, A. New Developments in Electron Microscopy. London: The Royal Society. pp. 45-50.
  6. Weakly, Brenda S. (1972) A Beginner's Handbook in Biological Electron Microscopy Edinburgh: Churchill Livingstone. pp. 4-7. ISBN 0443009082
  7. Nixon, W.C (1971). The General Principles of Scanning Electron Microscopy in Huxley, H.E and Klug, A. New Developments in Electron Microscopy. London: The Royal Society. pp. 45-50.
  8. Hunter, Elaine. (1993) Practical Electron Microscopy: A Beginner's Illustrated Guide (2nd ed.) New York and Oakleigh: Cambridge University Press. pp 3-7. isbn= 0-521-38539-3
  9. Hunter, Elaine. (1993) Practical Electron Microscopy: A Beginner's Illustrated Guide (2nd ed.) New York and Oakleigh: Cambridge University Press. pp 103-107, 114-112. isbn= 0-521-38539-3
  10. Alberts, B et al. (2009) Essential Cell Biology (3rd ed.) New York and Milton Park:Garland Science. p7.
  11. Woodford, Chris. (2009) How Electron Microscopes Work Explain That Stuff. Accessed 21/4/2010 <http://www.explainthatstuff.com/electronmicroscopes.html>
  12. Hunter, Elaine. (1993) Practical Electron Microscopy: A Beginner's Illustrated Guide (2nd ed.) New York and Oakleigh: Cambridge University Press. pp 122-130. isbn= 0-521-38539-3
  13. Nixon, W.C (1971). The General Principles of Scanning Electron Microscopy in Huxley, H.E and Klug, A. New Developments in Electron Microscopy. London: The Royal Society. pp. 45-50.
  14. Nixon, W.C (1971). The General Principles of Scanning Electron Microscopy in Huxley, H.E and Klug, A. New Developments in Electron Microscopy. London: The Royal Society. pp. 45-50.
  15. Alberts, B et al. (2009) Essential Cell Biology (3rd ed.) New York and Milton Park:Garland Science. p7.
  16. Woodford, Chris. (2009) How Electron Microscopes Work Explain That Stuff. Accessed 21/4/2010 <http://www.explainthatstuff.com/electronmicroscopes.html>
  17. Nixon, W.C (1971). The General Principles of Scanning Electron Microscopy in Huxley, H.E and Klug, A. New Developments in Electron Microscopy. London: The Royal Society. pp. 45-50.
  18. Harre R. Great Scientific Experiments: Twenty Experiments that Changed our View of the World 2002,p171, Dover Publications, USA, accessed on the 19/04/2010, <http://books.google.com.au/books?id=yTqoV1aJWtkC&pg=RA1-PA171&dq=jj+thomson+discovery+of+the+electron&client=firefox-a&cd=2#v=onepage&q=jj%20thomson%20discovery%20of%20the%20electron&f=false>
  19. de Broglie, L ,1929, The Wave Nature of the Electron: Nobel Lecture, December 12, 1929, Nobel Lectures, Physics 1922-1941, Elsevier Publishing Company, Amsterdam, 1965 Accessed at <http://nobelprize.org/nobel_prizes/physics/laureates/1929/broglie-lecture.html>
  20. Ruska, E 1987, The Development of the Electron Microscope and of Electron Microscopy, Reviews of Modern Physics, Vol 59 Issue 3 pp 627-638
  21. Ruska, E 1987, The Development of the Electron Microscope and of Electron Microscopy, Reviews of Modern Physics, Vol 59 Issue 3 pp 627-638
  22. Wells OC. and Joy DC.The early history and future of the SEM, Surface and Interface Analysis 200b, Vol38 Issue 12-13 pp 1738-1742,
  23. Breton, B 2009, The Early History and Development of The Scanning Electron Microscope, Scientific Imaging Group at Cambridge University Engineering Department, Accessed 18/04/2010, <http://www2.eng.cam.ac.uk/~bcb/history.htm>
  24. Wells OC. and Joy DC.The early history and future of the SEM, Surface and Interface Analysis 200b, Vol38 Issue 12-13 pp 1738-1742,
  25. Breton, B 2009, The Early History and Development of The Scanning Electron Microscope, Scientific Imaging Group at Cambridge University Engineering Department, Accessed 18/04/2010, <http://www2.eng.cam.ac.uk/~bcb/history.htm>
  26. Wells OC. and Joy DC.The early history and future of the SEM, Surface and Interface Analysis 200b, Vol38 Issue 12-13 pp 1738-1742,
  27. Breton, B 2009, The Early History and Development of The Scanning Electron Microscope, Scientific Imaging Group at Cambridge University Engineering Department, Accessed 18/04/2010, <http://www2.eng.cam.ac.uk/~bcb/history.htm>
  28. Breton, B 2009, The Early History and Development of The Scanning Electron Microscope, Scientific Imaging Group at Cambridge University Engineering Department, Accessed 18/04/2010, <http://www2.eng.cam.ac.uk/~bcb/history.htm>
  29. Pluk, H., Stokes D.J., Lich, B., Wieringa, B.,& Fransen, J.: " Advantages of indium–tin oxide-coated glass slides in correlative scanning electron microscopy applications of uncoated cultured cells ', page 353. Journal of Microscopy, 2008.
  30. Morinaga, K., Kido, H., Sato, A., Watazu, A. & Matsuura, M.: "Chronological Changes in the Ultrastructure of Titanium-Bone Interfaces: Analysis by Light Microscopy, Transmission Electron Microscopy, and Micro-Computed Tomography', page 59. Clinical Implant Dentistry and Related Research, 2009.
  31. http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=stryer&part=A1835
  32. Berry, J.P. & Galle, P.: " Phagocytosis by Alveolar Cells Studied by Electron Microscopy and Microanalysis: Comparison of Two Types of Particles', page 247. ENVIRONMENTAL RESEARCH, 1980.
  33. Glick, A.D., Getnick, R.A. & Cole, R.M.: "Electron Microscopy of Group A Streptococci After Phagocytosis by Human Monocytes', page 772. INFECTION AND IMMUNITY, 1971.
  34. Lherminier, J., Bonfiglioli, R.G., Daire, X., Symons, R.H., Boudon-Padieu, E.: "Oligodeoxynucleotides as probes for in situ hybridization with transmission electron microscopy to specifically localize phytoplasma in plant cells', page 41. Molecular and Cellular Probes, 1999.
  35. Binder, M., Tourmente, S., Roth, J., Renaud, M.,Gehring, W.J.: "In situ hybridization at the electron microscope level: localization of transcripts on ultrathin sections of Lowicryl', page 1646. The Journal of Cell Biology, 1986.
  36. Besse, S., Puvion-Dutilleul F.: "Distribution of ribosomal genes in nucleoli of herpes simplex virus type 1 infected cells', page 33. The European Journal of Cell Biology, 1996.
  37. Perkins, G.A. & Frey, T.G.: "Recent structural insight into mitochondria gained by microscopy', page 97. Micron 31, 2000.
  38. Koga, D. & Ushiki, T.: "Three-dimensional ultrastructure of the Golgi apparatus in different cells: high-resolution scanning electron microscopy of osmium-macerated tissues', page 357. Archives of Histology and Cytology, 2006.
  39. Barnes, S.H. & Blackmore, S.: "Scanning Electron-Microscopy of Chloroplast Ultrastructure', page 187. MICRON AND MICROSCOPICA ACTA, 1984.
  40. Nagler, FPO & Rake G: The Use of the Electron Microscope in Diagnosis of Variola, Vaccinia, and Varicella ', page 45. Journal of Bacteriology, 1945.
  41. Hazelton, P.R. & Gelderblom, H.R.: Electron Microscopy for Rapid Diagnosis of Infectious Agents in Emergent Situations', page 294. Emerging Infectious Diseases, 2003.
  42. Millette, J.R., Brown, R.S. & Hill, W.B.: Using environmental forensic microscopy in exposure science', page 20. JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY, 2008.
  43. Rai, R.S. & Subramanian, S.: Role of transmission electron microscopy in the semiconductor industry for process development and failure analysis', page 63. PROGRESS IN CRYSTAL GROWTH AND CHARACTERIZATION OF MATERIALS, 2009.
  44. Pyo, S.G. & Kim, N.J.: Role of interface boundaries in the deformation behavior of TiAl polysynthetically twinned crystal: In situ transmission electron microscopy deformation study', page 1888. JOURNAL OF MATERIALS RESEARCH, 2005.
  45. Dubochet, J., Adrian, M., Chang, J.J., Homo, J.C., Lepault, J., Mcdowall, A.W., Schultz, P.: CRYO-ELECTRON MICROSCOPY OF VITRIFIED SPECIMENS', page 129-228. QUARTERLY REVIEWS OF BIOPHYSICS, 1988.
  46. http://www.bbc.co.uk/dna/hub/A914302
  47. Dubochet, J., Adrian, M., Chang, J.J., Homo, J.C., Lepault, J., Mcdowall, A.W., Schultz, P.: CRYO-ELECTRON MICROSCOPY OF VITRIFIED SPECIMENS', page 129-228. QUARTERLY REVIEWS OF BIOPHYSICS, 1988.
  48. King, J.A.: "Role of transmission electron microscopy in cancer diagnosis and research', page 20. MICROSCOPY AND MICROANALYSIS , 2007.
  49. Hazelton, P.R. & Gelderblom, H.R.: Electron Microscopy for Rapid Diagnosis of Infectious Agents in Emergent Situations', page 294. Emerging Infectious Diseases, 2003
  50. Pluk, H., Stokes D.J., Lich, B., Wieringa, B.,& Fransen, J.: " Advantages of indium–tin oxide-coated glass slides in correlative scanning electron microscopy applications of uncoated cultured cells ', page 353. Journal of Microscopy, 2008
  51. Stokes, D.J.; "Recent advances in electron imaging, image interpretation and applications: environmental scanning electron microscopy', page 2771. Philosophical Transactions of the Royal Society London A, 2003
  52. UNSW Analytical Centre 2010, Homepage of Electron Microscope Unit UNSW Analytical Centre, UNSW. Accessed 22/4/2010 <http://srv.emunit.unsw.edu.au/Index.htm>


2010 Projects

Fluorescent-PCR | RNA Interference | Immunohistochemistry | Cell Culture | Electron Microsopy | Confocal Microscopy | Monoclonal Antibodies | Microarray | Fluorescent Proteins | Somatic Cell Nuclear Transfer