Djuro Koruga

Further results on the stability of linear nonautonomous systems with delayed state defined over finite time interval

This paper extends some basic results from the area of finite time and practical stability to linear, continuous, time invariant nonautonomous time-delay systems. Sufficient conditions of this kind of stability, for particular class of time-delay systems, are derived.

Direct observation of microtubules with the scanning tunneling microscope.

To observe surface topography of microtubules, we have applied scanning tunneling microscopy (STM), which can image metal and semiconductive surfaces with atomic resolution. Isolated microtubules fixed in 0.1% glutaraldehyde in reassembly buffer containing 0.8 M glycerol were imaged in air on a graphite substrate. The presence of microtubules in solution was verified by electron microscopy. At atmospheric pressure and room temperature, STM probing of both freeze‐dried and hydrated microtubules reveals structures approximately 25 nm in width, consisting of longitudinal filaments about 4 nm in width. These structures match electron microscopy images of microtubules and their component protofilaments. Microtubules imaged by STM frequently appear buckled and semiflattened. Top‐view shaded scans show what appear to be individual tubulin subunits within protofilaments. We believe these results represent the first direct STM observation of protein assemblies in which components can be identified. Although the microtubule image resolution described here is no better than that presently obtainable by other techniques (e.g., electron microscopy with freeze‐drying, shadowing, and/or negative staining), it is significant that suitably prepared biomolecules may be sufficiently conductive and stable for STM imaging, which is ultimately capable of atomic resolution. Further development of STM technology, computer‐enhanced image processing, and elucidation of optimal STM sample preparation indicate that STM and related applications will offer unique opportunities for the study of biomolecular surfaces.—Simić‐Krstić, Y.; Kelly, M.; Schneiker, C.; Krasovich, M.; McCuskey, R.; Koruga, D.; Hameroff, S. Direct observation of microtubules with the scanning tunneling microscope. FASEB J. 3: 2184‐2188; 1989.

Imaging Fullerene C60 with Atomic Resolution Using a Scanning Tunnelling Microscope

Abstract C60 was purified and imaged utilizing scanning tunnelling microscopy (STM) in a constant current mode. By fixing the Fullerenes on the substrate (“frozen state” - no movement or rotation), direct imaging of C60 with atomic resolution was possible, showing one pentagon and one hexagon carbon ring of C60.

Molecular networks as a sub-neural factor of neural networks

We describe a new approach in the research of neural networks. This research is based on molecular networks in the neuron. If we use molecular networks as a sub-neuron factor of neural networks, it is a more realistic approach than todays concepts in this new computer technology field, because the artificial neural activity profile is similar to the profile of the action potential in the natural neuron. The molecular networks approach can be used in three technologies: neurocomputer, neurochip and molecular chip. This means that molecular networks open new fields of science and engineering called molecular-like machines and molecular machines.

Microtubular screw symmetry: packing of spheres as a latent bioinformation code.

Oh (6/4) symmetry group describes face-centered-cubic sphere packing and derives informatkn coding laws.3 Hexagonal packing of protein monomers independent of the Oh (6/4) symmetry group has been used to explain the form patterns of viruses, flagella, and MT! Because hexagonal packing and face-centered-cubic packing of spheres have equal density, I use both to explain M T organization. Hexagonal packing may be used by fixing conditions. This is possible if tke centers of spheres lie on the surface of a cylinder (with radius equal to the Oh (6/4) unit sphere) and if (and only if) the sphere values in the axial direction (lattice) of the cylinder by order of sphere packing is the same as in the dimension in which the face-centered-cubic packing is done. Because 6-fold symmetry axis of Oh group is inverse, there must be two kinds of spheres (white and black) on the cylinder surface, but linked such that they have the dimension value in which the face-centered-cubic packing is done. This packing on the cylinder surface leads to “screw symmetry” (FIGURE 1). From coding theory, the symmetry laws of aand P-tubulin subunits lead to the conclusion that 13 protofilaments passes one of the best known binary error-correcting codes [K, (13, 26, S)] with 64 code words. Symmetry theory further suggests that on the surface of a circular cylinder in axial direction there must be a code of length of 24 monomer subunits. If the coding efficiency is used as a criterion of transmission, then 6-binary dimers of K, code should be coded to give a 4-dimer ternary sequence of Kz [24, 34, 131 code. This code may result from interaction between 24 tubulin monomers and high molecular weight proteins. Under the influence of Ca2+-calmodulin, binary dimers of K1 code give dimer ternary sequence of-K, code. In this way, KI and K2 codes, which result from the property of the Oh (6/4) symmetry group, lead a K (B6T4) transmission bioinforma-

Surface characterisation of Pb1−xMnxTe alloy by atomic force microscopy and magnetic force mode

Abstract In this paper the authors present the results of surface characterisation of a lead telluride alloy conducted by atomic force microscopy and magnetic force microscopy. Relationship between surface morphology, in the range of several nanometres, and the magnetic properties allows precise determination of nanomagnetic particles size with their distribution within a scanned area. This method allows the characterisation of nanoparticles in dimensional and magnetic sense since the paramagnetic and diamagnetic range can be examined.

Molecular electronics and neural networks: significance of ionic structure

The structure of a low-dielectric-strength, weakly ionized gaseous medium is considered and its ionic concentration is estimated. The significance of the results for understanding the role of ULF brain waves in psychological information processing is considered, starting with the assumption that consciousness is associated with the electromagnetic component of brain waves. Implications for brainlike neural networks are discussed.<<ETX>>

Classical and Quantum Information Processing in DNA-Protein Coding

In scientific fields, it is crucially important to understand how internal structure relates to the external form. The internal molecular structure of DNA is the key to understand how it works, but it is too far to be fully understood. Biomolecules are complex nanosystems, in which structure, energy, and information are coupled in non-conventional way.

Fibonacci Nanostructures for Novel Nanotherapeutical Approach

Abstract In this chapter the investigation of a new type of nanomaterial, nanoharmonized substance (NHS) whose composition of matter follows a harmonized form (Fibonacci law: Φ/ϕ) is presented. Conducting its vibrations to water molecules in near surroundings could force biomolecules to recover its natural vibration mode. The discovery of fullerene material brought new possibilities in science and technology. However, it is toxic in concentrations higher than 10 ppb. To overcome this problem, a water stabilizing belt has been made around carbon hydroxyl molecule and in the range of 106−109 ppb it becomes nontoxic. Energetically stabilized nanoharmonized substance could be considered biomimetic nanomaterial, which mostly in its symmetrical and energetically properties resembles clathrin—a protein with the most important process of intracellular transportation. To investigate properties and efficiency of nanoharmonized substance (NHS), Aquaphotomics is used alongside gold standard biopsy and tissue examination.

Molecular Control Network

Multicellular organisms are composed of biological units — cells, which are highly organized. Cells cannot act independently, but they possess their own regulatory mechanisms which provide their functions. Centrioles are the main sensory and controlling systems in cells.