Chemiml Technology, MOSCOW, U.S.S.R.In considering the materials used as adhesives it is easy to note that almost all of them are high polymers. Thermoplastic and thermosetting resins, natural resins, cellulose derivatives, proteins, and rubbers are known to be used for bonding. It is important that only high molecular substances with their long-chain molecules have pronounced adhesive properties.Only such inorganic compounds as cements and solders can be considered as nonpolymeric adhesives. However, the bond formation with cements and solders takes place in accordance with completely specific mechanism (fusion of crystals, welding) which has little in common with the formation of the usual adhesive bond and can only conventionally be considered as bonding. As far as bonding with sodium silicate is concerned, it is established at present that sodium silicate can be considered as an inorganic high molecular substance.The present paper is a discussion of the mechanism of specific adhesion of polymers to each other. This case of adhesion is of great practical importance. The production of tires, confection of rubber products, production of rubber wear by glueing, as well as bonding and welding of plastics, and sizing of paper are all based on polymer-to-polymer adhesion. The technology of most of the aviation materials and of the artificial leather is also entirely based on the process of polymer .to-polymer bonding. Finally, bonding with polymers is widely used in wood processing and plywood manufacture, civil engineering, during the assembly of airplanes, and in a good number of other branches of engineering. Polymer-to-metal adhesion is not discussed here because of a special character of polymer-metal bond, which is probably chemical in most cases. The adhesion of polymers to inorganic glass is not considered here either though glass represents inorganic polymer and the authors of the present paper have some grounds to believe that the mechanism of polymer-to-glass adhesion in some cases is similar to that of polymer-to-polymer adhesion.Attempts at theoretical generalization of the results obtained were made by the first investigators of bonding.2-6 However, the importance of the earlier investigations in the development of a theoretical approach to the bonding of polymers is depreciated by the fact that in most cases bonding of surfaces (wood, metal, glass, etc.) has been studied by means of the layer of i?.5

The diversity of techniques employed in modern sensing nanodevices is crucial for large-scale use of sensors in multifunctional technological cycles. We propose a new concept of selective detection of gases and liquids based on the formation of an original quantum system and registration of its energy states in dynamic mode using dendrite point contacts synthesized electrochemically in the probed medium. The in situ synthesis of nanosized dendrite point contacts is shaped by the cyclic switchover effect which takes place in an electrolyte in contact with the analyzed medium and results in consecutive cycles of the formation and destruction of an electrochemical gapless electrode system. Conductivity of such point contacts demonstrates quantum behavior driven by the shell effect which determines the geometry of their conducting channels. Temporal dependence of dendrite point contact electrical resistance measured in dynamic mode is characterized by a step-like structure which reflects the metastable quantum states of the system whose distribution can be presented in the form of a conductance histogram. The histogram is a unique fingerprint of the probed medium and can thus be used to unambiguously identify it. The dynamic mode scanning of the energy states of point contact quantum systems proposed here makes it possible to develop a universal method for selective detection of many gaseous and liquid media including such hard to detect substances as methane and rare gases. The new approach is expected to prove its efficiency in investigating quantum effects for various sensor applications and stimulate the development of the next generation of highly selective nanodevices. Graphical abstract The new concept of selective detection of gases and liquids is based on the registration of quantum states of nanosized dendrite point contacts synthesized in the probed medium.

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Of all modern nanosensors using the principle of measuring variations in electric conductance, point-contact sensors stand out in having a number of original sensor properties not manifested by their analogues. The nontrivial nature of point-contact sensors is based on the unique properties of Yanson point contacts used as the sensing elements. The quantum properties of Yanson point contacts enable the solution of some of the problems that could not be solved using conventional sensors measuring conductance. In the present paper, we demonstrate this by showing the potential of quantum point-contact sensors to selectively detect components of a gas mixture in real time. To demonstrate the high efficiency of the proposed approach, we analyze the human breath, which is the most complex of the currently known natural gas mixtures with extremely low concentrations of its components. Point-contact sensors allow us to obtain a spectroscopic profile of the mixture. This profile contains information about the complete set of energy interactions occurring in the point contact/breath system when the breath constituents adsorb to and desorb from the surface of the point-contact conduction channel. With this information we can unambiguously characterize the analyzed system, since knowing the energy parameters is key to successfully identifying and modeling the physicochemical properties of various quantum objects. Using the point-contact spectroscopic profile of a complex gas mixture it is possible to get a functional dependence of the concentration of particular breath components on the amplitude of the sensor output signal. To demonstrate the feasibility of the proposed approach, we analyze the point-contact profiles from the breath of several patients and compare them with the concentrations of serotonin and cortisol in the body of each patient. The obtained results demonstrate that the proposed methodology allows one to get an effective calibration function for a non-invasive analysis of the level of serotonin and cortisol in the human body using the point-contact breath test. The present study indicates some necessary prerequisites for the design of fast detection methods using differential sensor analysis in real time, which can be implemented in various areas of science and technology, among which medicine is one of the most important.