The Nanosystems

These new methods of nonequihbrium statistical mechanics can be applied to understand the fluctuating properties of out-of-equilibrium nanosystems. Today, nanosystems are studied not only for their structure but also for their functional properties. These properties are concerned by the time evolution of the nanosystems and are studied in nonequilibrium statistical mechanics. These properties range from the electronic and mechanical properties of single molecules to the kinetics of molecular motors. Because of their small size, nanosystems and their properties such as the currents are affected by the fluctuations which can be described by the new methods. 

Acknowledgments This work was supported by the Nanosystems Initiative Munich (NIM) and the Center for Integrated Protein Science Munich (CiPSM) and the SFB 749. 

Let us consider a simple situation, when the nanosystem is coupled only to the end site of the ID lead (Fig. 3). From (26) we obtain the matrix elements of the self-energy... 

After all, we want again to calculate the current through the nanosystem. We assume, as before, that the contacts are equilibrium, and there is the voltage V applied between the left and right contacts. The calculation of the... 

The physical sense of this expressions is quite transparent, they describe the quantum amplitudes of the scattering processes. Three functions scattering state in the Landauer-Biittiker theory. Note, that G here is the full GF of the nanosystem including the lead self-energies. 

Assume that a noninteracting nanosystem is coupled weakly to a thermal bath (in addition to the leads). The effect of the thermal bath is to break phase coherence of the electron inside the system during some time Tph, called decoherence or phase-breaking time. rph is an important time-scale in the theory, it should be compared with the so-called tunneling time - the characteristic time for the electron to go from the nanosystem to the lead, which can be estimated as an inverse level-width function / 1. So that the criteria of sequential tunneling is... 

To proceed, we introduce the following Hamiltonian, describing single electron tunneling and charging of the nanosystem state... 

The current from the left (i = L) or right (i = R) contact to the nanosystem is determined by (note, that we consider e as the charge of the electron (negative) or the hole (positive))... 

There is clear evidence from Table 2 that some of the nanosystems indicated are based on conventional colloidal chemistry, and their characteristics are well established and understood. The descriptions below deal mainly with systems deemed nonconventional and cover some of the key novel properties derived from or utilized as part of their construction. 

Two obvious routes of human contact with nanoparticulates are the skin and via inhalation. Given the size of the particles, there may be a propensity for absorption into the systemic circulation. In some cases the nanosystems are engineered to achieve enhanced systemic absorption. The established methodology for toxicological assessment of new materials should be adhered to, and the discussion below is intended only to touch upon some of the immediate safety concerns that should be understood and addressed when dealing with nanomaterials. 

Figure 22.2 Fates of nanoparticulates after i.v. injection and local administration to the target tissue. After i.v. injection, the particles should avoid aggregation and embolization to avoid entrapment into the lung capillaries. Kuppfer cells of the liver phagocytose major part of the nanoparticulate dose (illustrated on the right), but this may be slowed down by nanoparticulate surface modifications. Inthetargettissue (on the left), the nanosystem should enter the vascular endothelial cells, if they are the target cells, like in the case of neovascularization. Otherwise, they should escape from the vasculature, dock to the...

It is important to realize that in the first and second option, the local concentration of the free drug is increased by the nanosystems. The drug may be absorbed by passive diffusion or active transport, but it is not specifically carried by the nanoparticulates. 

This work was supported in part by the Nanosystems, nanomaterials and nanotechnologies Program of the National Academy of Sciences of Ukraine. 

When the evolution of the nanosystem as whole (including the processes of ordering and self-organization of the nanostructure nanoelements) is investigated, the movement of each system nanoelement is considered as the movement of a single whole. In this case, the translational motion of the... 

Vakhrouchev, A.V Modeling of the nanosystems formation by the molecular dynamics, mesodynamics and continuum mechanics methods. Multidiscipline Modeling in Material and Structures. 2009, 5(2), 99-118. 

Polymers have become essential in all areas of health, from the solid materials used, for example, for prostheses, catheters and blood bags to the nanosystems developed for the vectorization of active substances and for diagnostics [GAU 03]. Among all these devices, some are single use (syringes, infusion sets, etc.), while others are introduced into the body for a period which is a priori indefinite (articular prostheses, vascular substitutes, artificial crystalline lenses, stitches thread, etc.). 

In present work processes of dissolutions are considered for stable platinum nanoclusters and binary nanocluster PtMe (Me is the transition metals, namely Cr, Fe, Co, Ni, Ru) with core-shell stmctuie and n = 42,m = 13 atoms, as well as their surface interaction with particles of environment, i.e., H/), O, OH, H/F, Cf. So, we need examine reaction ability of binary nanoclusters in such environment, including prediction of the nanosystem properties. Evidently, to solve such task one must possess data about potentials of all particle interaction in a chosen system. 

In order to estimate the prospects of the nanosystems developed for practical use, preclinical investigations were started. It was shown (MTT-test) that the magnetic fluids Fe304/Na ol. and FeaO /Na oL/PEG (Figure 10.23) with magnetite content C = 10—50 pg/ml show practically no cytotoxic activity in vitro upon the cells of breast cancer line MCF-7. 

Overall, for the moment we remain with the fact electronegativity and chemical hardness Zmay be worth combined to produce an energy that is better and better representing the pi-electionic systems with the increasing complexity of the system on focus the way in which this depend on the carbon containing system, alone or in combinatimi with heteroatoms or for the nanosystems systems without carbon. 

Fig. 4.21 Dependences of the linear ME coefficient on the nanosystem characteristic size (film thickness hla, wire or spherical particle diameter 2R/a). The I i near ME coupling is regarded absent in the bulk material...

Among different (like flexoelectric, flexomagnetic etc.) flexoeffects, the influence of flexoelectric effect on the nanosystem properties had been studied in most details. One can conclude that even rather moderate flexoelectric effect significantly renormalizes all the polar, piezoelectric and dielectric properties and the correlation radius in particular. The effect also suppresses the size-induced phase transition from ferroelectric to paraelectric phase and thus stabilizes the ordered phase in ferroic nanoparticles. 

Today the relevance of thermodynamic formalism and applicability of statistical physics are questionable when the nanosystems, the systems far from equilibrium and the systems with strong interactions begin to be studied. First of all the problems appear for the definition of the temperature that is the key concept in the formalism of thermodynamics and statistical physics. The assumptions used to define the temperature have to be treated very carefully in the cases of nanosystems, systems with strong interactions and other complex systems. ... 

The particles have to be delivered specifically to cancer cells without damaging healthy tissues following NIR irradiation. Specific targeting agents can be attached to the nanoparticles, such as FA or antibodies. The PS should not leak from the nanosystem in the biological environment. 

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