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Gerasimos (Gerry) D Danilatos


Environmental Scanning Electron Microscopy (ESEM)

Publications on ESEM


Viscoelasticity (Dynamic Mechanical Properties of Keratin Fibres) - Ph.D. Thesis

Publications from Ph.D. Thesis (viscoelasticity)


Short biography

GERASIMOS (Gerry) D. DANILATOS was born on the Greek island of Cephalonia but in 1953 he and his family moved to the city of Patra after the island was devastated by a strong earthquake. There, he finished his primary and secondary schooling. After two years of national service in the army, he studied at the National and Kapodistrian University of Athens where he received his Physics Degree with distinction, in 1972. Gerry migrated to Australia at the end of 1972 and obtained his Ph.D. from the University of New South Wales (UNSW) in January of 1978. His thesis entitled "Dynamic Mechanical Properties of Keratin Fibres " involved research into the viscoelastic/molecular properties of wool fibres . He married in 1979 and has two children.

Dr. Danilatos is best known for his pioneering work on the environmental scanning electron microscope (ESEM). The establishment of ESEM did not occur overnight and without trouble. It was the tenacity and absolute conviction by Dr. Danilatos in his technology that kept him going for a long time despite meager support and numerous obstacles he had to face during the critical early years of development. He indeed achieved an extraordinary result in an unconventional way : Following an initial investigation at the University of New South Wales at the beginning of 1978 into the prior attempts to introduce gas in electron microscopes, he was supported by an external  grant from the Wool Research Trust Fund at the recommendation of the Australian Wool Corporation (AWC) to apply his work to wool fiber research that allowed him at the same time to develop his microscopical techniques. Not quite understood and supported by his peers in that early phase, in 1983 he had to transfer his entire laboratory to the Commonwealth Scientific and Industrial Research Organization (CSIRO ). There, he could further work on his ESEM undisturbed while applying it to wool research under the continued support by AWC until 1986. By that time the ESEM had reached a high level of development that appeared to fall outside the programs of work in his Organization. Luckily, by that critical time, ElectroScan Corporation in USA was just formed for the purpose of manufacturing a gaseous microscope and the Danilatos publications professed exactly what the manufacturer needed . CSIRO promptly agreed to surrender the old ESEM prototype, and his entire laboratory was transferred to private premises.  Thus the ESEM Research Laboratory was founded, a private research and development unit of electron microscopy that has played a key role in the development of ESEM ever since.  It was initially funded by ElectroScan Corporation and Dr. Danilatos was the Director of his Lab and the Chief Scientific Advisor of ElectroScan until 1993. Danilatos was thus able to completely independently continue his work in his ESEM research in Sydney, while ElectroScan undertook to manufacture the first commercial ESEM under license and assignment of various patents. It has been from this laboratory that some of the most voluminous and best works on ESEM have originated. He has continued to work and produce results until the present day while he endeavors to help manufacturers to produce new generations of commercial ESEMs with new capabilities and attuned to optimum operation. He has developed brand new techniques and methods awaiting their implementation.

Prior to above, he was Senior Research Scientist at CSIRO (1983-1986). Prior to that, he was Project Scientist (1980-1983) and Professional Officer (1978-1979) at the UNSW.  He has served as member of the Scientific Advisory Board of the journal Scanning (1983-1988) and has been a member of the Royal Microscopical Society (1979-1994), of the Microscopical Society of America (1986-1993) and of the Australian Society of Electron Microscopy (1979-2008).

Danilatos further worked for a period of time to help LEO (now Zeiss) enter the ESEM market with a new commercial ESEM that allows the use of secondary electron detection and extended specimen chamber pressure.

He is the senior author on over sixty publications in international refereed journals including three major chapters on ESEM and has obtained ten patents on various aspects of ESEM.

He received the Ernst Abbe Memorial Award by the New York Microscopical Society in 2003 .

He now plans to bring his work to its logical conclusion by further research and new publications on ESEM to be used by the scientific and manufacturing communities. His works constitute an introduction and the basis in the understanding and use of ESEM. It is certainly no exaggeration that Dr. Danilatos alone and single-handedly, despite numerous difficulties and obstacles, pioneered, invented and developed this unique ESEM instrument to a point where the rest of the scientific and manufacturing world can further develop, expand, apply, use, benefit and enjoy.




The complex modulus of single keratin fibres has been studied at various extensions or times as well as at different relative humidities, temperatures and frequencies. Two parameters of the complex modulus were measured, namely, the dynamic modulus and the loss angle.

To carry out measurements for the above studies, a dynamic mechanical tester was designed and constructed. By using a piezo-electric element, the apparatus allows for measurements to be taken in the frequency range 6 Hz to 1500 Hz, while with an environment conditioning chamber the full range of relative humidities and the range of -100 to +50 0C for temperatures can be covered. Fine fibre samples can be extended in the apparatus and tested at each extension. Considerable precautions were taken in the apparatus to reduce noise because of the small values of the signals detected.

By using the above equipment, it was found that the modulus of wool fibres decreases with strain up to intermediate extensions of about 20% and then increases with higher extensions. The loss angle variation with extension is inverse to the modulus changes. The complex modulus was also measured while fibres were extension cycled or relaxed at fixed strains. More measurements were taken under other specific conditions of strain. All of these results, it was shown, could be explained by the application of a two-phase structure model of keratin: one crystalline phase C being relatively impenetrable to water and possessing elastic properties at all extensions, and the other phase M being water penetrable and acting mechanically as a viscoelastic solid.

Measurements on fibres were carried out during abrupt relative humidity changes at a constant frequency and temperature. For an abrupt relative humidity increase, it was found that the loss angle vs. time exhibits an overshoot at the time when the absorption is nearly completed, while the modulus curve is changing markedly at the same time. This result was compatible with the suggestion that the structural mobility of the keratin fibre reaches a maximum at the time when absorption is almost complete.

The complex modulus of wet keratin fibres was measured in the frequency range of 6-1500 Hz, at different temperatures between 0.2-45 0C. Some measurements were taken at different relative humidities. These results together with results of other workers indicated the presence of a characteristic transition process in keratin dependent strongly on the water content. This process was attributed to the main chain motion in the M phase.

Detailed description of these works is given in the literature below.



Publications from Ph.D. Thesis on viscoelasticity


  1. Danilatos GD (1977) Dynamic Mechanical Properties of Keratin Fibres. Ph.D. Thesis, University of NSW, Sydney, Australia.

  2. Danilatos G and Feughelman M (1976) The internal dynamic mechanical properties of a -keratin fibers during moisture sorption. Tex. Res. J. 46:845-846.

  3. Danilatos G and Feughelman M (1979) Dynamic mechanical properties of a -keratin fibres during extension. J. Macromol. Sci.-Phys. B16(4):581-602.

  4. Danilatos G and Feughelman M (1980) The microfibril-matrix relationships in the mechanical properties of keratin fibers. Text. Res. J. 50:568-574.

  5. Danilatos GD (1980) Design of a fibre viscoelastometer. J. Phys. E: Sci. Instrum. 13:1093-1098.

  6. Danilatos GD and Postle R (1981a) Dynamic mechanical properties of keratin fibres during water absorption and desorption. J. Appl. Pol Sci. 26:193-200.

  7. Danilatos GD and Postle R (1981b) Low-strain dynamic mechanical properties of keratin fibres during water absorption. J. Macromol. Sci.-Phys. B19(1):153-165.

  8. Danilatos G and Postle R (1981c) Dynamic mechanical measurements on some man-made fibres. J. Text. Inst. 72:90-92.

  9. Danilatos GD and Postle R (1983) The time-temperature dependence of the complex modulus of keratin fibres. J. Appl. Pol. Sci. 28:1221-1234.

  10. Feughelman M, Danilatos GD and Dubro D (1980) Observations on the mechanical properties of microfibrils and matrix in a -keratins. Fibrous Proteins: Scientific, Industrial and Medical Aspects, edited by Parry DAD and Creamer LK, Vol. 2, Academic Press, London.


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