stochastic; tissue; molecular crystals; polarity; bi-polar state; scanning pyroelectric microscopy; phase sensitive second harmonic microscopy
Hulliger Jürg, Ravi H. K., Simona F., Cascella M. (2012), Molecular Origin of Piezo- and Pyroelectric Properties in Collagen Investigated by Molecular Dynamics Simulations, in J. Phys. Chem.
, B2012(116), 1901-1907.
Hulliger Jürg, Wübbenhorst M., Putzeys T., Burgener Matthias (2011), Observation of Permanent Polarization Distributions in Bioorganic Materials Using a Highly Sensitive Scanning Pyroelectric Microscope, in IEEE, 14th International Symposium on Electrets (ISE)
, 2011, 187-188.
Aboufadl Hanane, Hulliger Jürg (2011), One-hundered eighty degree domain detection by surface phase sensitive second harmonic generation microscopy of polar materials, in Cryst Growth Des.
, 11(2011), 3045-3048.
Makowski T, Berger Ricarda, Aboulfadl Hanane, Hulliger Jürg, Tracz A (2011), Aligment of PHTP-DNAA inclusion crystals by zone casting, in Optical Mater
, 33(2011), 1464-1468.
Hulliger Jürg, Wüst Thomas, Brahimi Khadidja, Burgener Matthias, Aboulfadl Hanane, A stochastic principle behind polar properties of condensed molecular matter, in New J. Chem.
Hulliger Jürg, Wüst Thomas, Brahimi Khadija, Martinez Garcia Julio Cesar, Can mono domain polar molecular crystals exist?, in Cryst. Growth Des.
Hulliger Jürg, Aboulfadl H., Burgener Matthias, Benedict J., Kahr B, Polar alignment of dye molecules in sectors of host lattices reveled by phase sensitive second harmonic generation and scanning pyroelectric microscopy, in CrystEngComm
, 2012(14), 4391-4395.
Polar symmetry of real objects, molecules and crystals is a fundamental property for establishing complex functions. In the world of crystals, there are two essentially different ways to generate a polar structure : (i)by nucleation and replication, or (ii)by a Markov-type process involving polarity by growth - irrespective of the symmetry created by nucleation.This completely new concept (ii) for developing / understanding materials by a Markov chain mechanism was independently discovered by Harris et al. and Hulliger et al. in 1997. Since then the group in Berne has elaborated basic theoretical and experimental means to investigate this phenomenon covering all kind of materials: macroscopic heap formation, crystals of low molecular weight and long chain proteins forming tissues. In 2003, the applicant presented a first theoretical model explaining experimentally known pyroelectric effects in collagenous tissues. Nowadays, new scanning probe techniques reveal more and more of the fine structure of growth induced polarity in tissues.In view of basic features associated with stochastic polarity formation being elaborated in detail, there are still basic issues which merit full understanding and experimental demonstration.The present proposal will thus focus on the following main issues :1) Stochastic theory predicts for natively polar molecular crystals a fundamental process of dipole inversion along only one of the directions of the unique axis. Here, a full theoretical elaboration of the phenomenon along with experimental confirmation by crystallization is attempted. This would establish a general mechanism expressed for a polar space group of dipolar compounds.2) Monte Carlo simulations and analytical theory have shown that forming solid solutions is an approach yielding polar materials by high probability. Here, specific molecular examples will be investigated to confirm basic features of polar solid solutions. Examples are e.g. mixtures of natively non polar crystals of dipolar components which by solid solution formation become polar.3) The number of investigated single component crystals featuring grown-in polarity is still small, although preliminary tests on most materials have revealed such an effect. Here, prime examples for further studies are to be found.4) Phase sensitive second harmonic generation will be applied to thin cuts of tissues to establish maps of bi-polarity distributions at micrometer resolution. Theoretical and experimental work will attempt to determine the absolute sign of tissue polarity, this to verify / disproof theoretical predictions made by the applicant (2003). Polarity maps may serve as diagnostic tool and knowledge on tissue polarity is a base to understand regenerative healing of tissues by treatment with ultra sound.In essence, this proposal attempts to investigate polarity formation where ever it appears in nature, along with basic theoretical modeling and application of advanced experimental techniques for investigation.