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In connection with the development of methods for the delivery of lipophilic drugs in a bioavailable form, we have employed an integrated approach to the investigation of the adsorption of an antihypertensive drug, felodipine, at interfaces that simulate the surfaces of different carriers. Isotherms have been plotted for felodipine adsorption from solutions in heptane (C = 2.13 × 10–5 − 4.26 × 10–4 M) at interfaces with water and silver metal, as well as for the compression of drug monolayers formed on a water surface from the heptane solutions. The quantitative characteristics of the studied felodipine layers have been determined, and their phase state and the most probable conformation of adsorbed drug molecules have been analyzed taking into account the data of molecular dynamics simulations. The phase state of the felodipine layers at the heptane/water interface is adequately described by the van Laar equation. A bilayer is formed at the silver surface. A phase transition from a gaseous state to a liquid-expanded state has been revealed for the felodipine layers.

The composition and technology for the preparation of a combined water solution of hydrophobic plant extracts, eucalymine and estifan are developed. The concentration of surfactants (Tween 20 and 80) and soya lecithin that is optimal for obtaining stable miniemulsion systems is determined. The sizes and zeta potential of the obtained dispersed nanoscale particles are established.

Langmuir's method was used to investigate the structures of water/air-boundary monolayers of statistical and gradient copolymers of styrene and acrylic acid. The differences found in the laws governing the formation of monolayers of copolymers of different microstructure enable us to anticipate the technique of transferring these monolayers onto a solid support from an energetically homogeneous moving boundary, combined with variation in the microstructure of the copolymers, to be very promising for the fine control of their adhesion characteristics.

The regularities of the adsorption modification of different solid surfaces with aqueous solutions of amino-acid derivatives of fullerene C60 (ADF) that contain the maleimide and dipeptide addends were studied by the methods of wetting and Quartz Crystal Microbalance (QCM). It was found that, despite the absence of surface activity at the solution-air interface, ADFs are well adsorbed at the solution-solid interface. On high-energy surfaces with different charges in aqueous media, at neutral pH, the studied ADF act as ionic surfactants with polar groups charged opposite to the solid surface. The modification of polymers with AFD solutions results in the hydrophilization of their surfaces as in the case of classical low-molecular surfactants.

It is established that the two-dimensional crystallization of sodium chloride on the surface of a biopolymer film (film of a glycoprotein, mucin), which is used as a template, gives rise to the formation of crystals with unusual morphology—in particular, dendrites. This type of crystallization is observed in two cases—namely, when drying a film formed from a salt-containing mucin dispersion and when drying a salt solution droplet on the surface of a dry mucin film obtained from a salt-free mucin dispersion. Mechanisms leading to unusual salt crystallization are discussed, and the role of specific interactions of sodium chloride with mucin is shown.

The colloidochemical properties of new cationic surfactants synthesized from fatty acids of palm oil and diethylenetriamine are first studied. It is found that, at solution pH below 6.0, the examined surfactants exist mainly as salts formed from protonated surfactant molecules and residues of strong acids, e.g., hydrochloric acid. In the pH range above 7.0, the protonated and nonprotonated forms of the surfactants are at equilibrium, which shifts to the nonprotonated form with an increase in pH. The analysis of interfacial tension isotherms shows that the minimum values of the interfacial tension are achieved at pH 7.0 when the concentrations of the protonated and nonprotonated forms of surfactant molecules are equal. New cationic surfactants are used as emulsifiers in emulsion polymerization of styrene. It is found that stable polystyrene latexes with narrow particle size distributions and high positive ζ potentials (as high as +68.4 mV) can be obtained at styrene concentration in an initial emulsion of 25 vol % and surfactant concentration in an aqueous phase of 2 wt %. A hydrogen peroxide-iron(II) salt redox system is used as an initiator of polymerization at component concentrations equal to 5 and 0.05 wt % of the monomer, respectively.

The influence of a nonionic surfactant (polyoxyethylene(20)sorbitan monooleate, Tween 80) on the rheological behavior of concentrated toluene-in-water emulsions stabilized by globular protein (bovine serum albumin, BSA, C = 5 × 10−5 M) at 22 °C have been studied using different methods of shear rheology. The systems under investigation are non-Newtonian liquids while the yield stress is observed at low shear stresses. The dependencies of the yield stress and shear viscoelasticity on the total concentration and surfactant/protein molar ratio were discussed. The increase in concentration of a nonionic surfactant leads to the decrease in viscosity and suppression of emulsion elasticity. A sharp jump in the rheological properties appears at a minimal concentration of the added Tween 80, whereas elasticity practically disappears, viscosity abruptly decreases and emulsions become unstable against coalescence in approaching concentration of the nonionic surfactant to 1 × 10−3 M. The observed effects can be attributed to the gradual displacement of a high-molecular-mass component (protein), which is responsible for the emulsion elasticity, from the stabilizing (interfacial) layers by the nonionic surfactant.

Viscoelastic properties of highly concentrated toluene-in-water emulsions stabilized by mixtures of bovine serum albumin and a nonionic surfactant, polyoxyethylene(20)sorbitan monooleate, are studied by a dynamic method in a wide frequency range. It is shown that an increase in the relative content of the surfactant results in a suppression of the system elasticity and a decrease in the relaxation time. A direct correlation is found between the dynamic and steady rheological characteristics of the systems under examination. The latter fact confirms indirectly that the viscoelasticity of the emulsions is due to the presence of the high-molecular-mass component in interfacial layers.

Mixed monolayers of bovine serum albumin (BSA) with a nonionic surfactant (Tween 80) are obtained by spreading solutions containing both components over the surface of a subphase (water with pH 6) over a wide range of solution compositions. According to compression-expansion isotherms, the mixed monolayers are of the condensed type when the BSA concentrations in the solution are far higher than or equal to the surfactant concentration. Such monolayers mostly consist of BSA-Tween 80 (1: 1) complexes. In contrast, a BSA monolayer is of the expanded type. When Tween 80 in the solution prevails over Tween 80, the monolayers become unstable. The results of this work pertain to the monitoring of the properties of protein-surfactant mixtures and design of Langmuir-Blodgett (LB) films.

Stable black films are prepared for the first time from aqueous solutions of Tween 80-bovine serum albumin mixtures. Conditions for their formation and stabilization factors are studied in a Scheludko-Exerowa cell by microinterferometry. It is found that such films are formed when saturated surface layers consist of surfactant-protein 1: 1 complexes, Tween 80 molecules, or their mixtures. A possible mechanism for the thinning of liquid layers and the stabilization of black films is discussed.

Changes in the rheological properties of a model concentrated oil-in-water emulsion stabilized with globular protein (bovine serum albumin) upon the addition of nonionic surfactant polyoxyethylene (20) sorbitan monooleate (Tween 80) are studied. Non-Newtonian behavior is typical of the emulsions in question; moreover, they are characterized by the existence of yield stress. At stresses above the yield stress, the viscosity drops not immediately but after the intermediate Newtonian region at the flow curve. For all systems studied, the total flow curve is exhibited with the minimum Newtonian viscosity that is adequately described by the Cross formula. An increase in the Tween 80 concentration leads to a decrease in the viscosity of emulsion. Two threshold phenomena on the concentration dependences of rheological properties are revealed: at low concentration of added nonionic surfactant, the yield stress drops abruptly, whereas the viscosity lowers considerably with an increase in surfactant concentration to 1 × 10−3 mol/l and the emulsion becomes unstable. The effects observed can be explained by the gradual displacement of high-molecular-weight stabilizer from interfacial layers and its replacement by nonionic surfactant.

The influence of a chemical modification (hardening) on the behavior of photographic gelatins at an interface has been investigated. It has been established, using the Langmuir monolayer method, that the properties of the surface layers of a modified gelatin change at the water-air interface and the depth of modification influences the surface activity of the gelatin. The surface properties of gelatin gels were investigated by the method of wetting depending on the hardener nature and the gelatin molecular-mass composition. It has been established that the hydrophilicity of gelatin gels increases with increase in the content of α-chains and the surface of gelatin gels is additionally hydrophilized as a result of their modification.

The properties of photographic gelatins in the aqueous phase were studied as influenced by hardeners of various types. The effect of molecular-weight distribution of gelatins, reagent ratios, and temperature on hardening was analyzed.

The behavior of gelatin chemically modified with N-hydroxysuccinimide ester of caprylic acid at the aqueous (NH4)2SO4 solution–air interface is studied. The compression isotherms of gelatin monolayers whose pattern is dependent on the degree of gelatin modification are obtained. It is established that the area corresponding to the beginning of isotherm rise, two-dimensional pressure of completely compressed monolayer, and the modulus of monolayer surface elasticity increase with the degree of gelatin hydrophobization. The surface (“adsorption”) activity of gelatin with the modification degree of 85% is approximately threefold higher than for the initial gelatin.

Aqueous dextran solutions, polyhexamethyleneguanidine hydrochloride and Sovidone and their mixtures with taurine were used to form stable ultrathin protective films for ophthalmological use. Addition of taurine to dextran and polyhexamethyleneguanidine solutions induced an association between polymer macromolecules in the two-dimensional film and a decrease in the surface activity of the solution. Addition of taurine to Sovidone solutions altered the conformation of macromolecular globules and increased the surface activity of the solution. Use of these solutions as the bases for eye drops did not harm the lipid layer of the tear film, and that rapidly formed polymer films could successfully be replaced by natural lipids via natural processes during recovery of the functions of the tear glands.

We present a phenomenological model which describes the formation of a Centauro fireball in the baryon-rich projectile fragmentation region in nucleus-nucleus interactions in the upper atmosphere and at the LHC, and its decay to non-strange baryons and Strangelets. Strangelets are assimilated to the "strongly penetrating component" frequently observed accompanying hadron-rich cosmic ray events. We describe the CASTOR subdetector for the ALICE experiment at the LHC. CASTOR will probe, in an event-by-event mode, the very forward, baryon-rich phase space 5.6 ≤ η ≤ 7.2 in 5.5 × A TeV central Pb + Pb collisions. It will look for events with pronounced imbalance between hadronic and photonic content and for deeply penetrating objects. We present results of simulations for the response of the CASTOR calorimeter to the passage of Strangelets. © 2001 Elsevier Science B.V.

We present a phenomenological model for the formation and decay of a cosmic ray Centauro fireball in the baryon-rich projectile fragmentation rapidity region in nucleus-nucleus interactions. Our model naturally incorporates the possibility of Strangelet formation, Strangelets being conjectured to be the “strongly penetrating component” observed in hadron-rich cosmic ray events. Based on this model we have performed Monte-Carlo simulations to study the Centauro and Strangelet dynamic and kinematic characteristics in central Pb+Pb collisions at LHC energies, as well as their identification by the detector system CASTOR. CASTOR is being developed for the ALICE heavy ion experiment at the LHC and will probe the very forward pseudorapidity region 5.6 less than or equal to eta less than or equal to 7.2, characterized by very high baryon density. CASTOR is optimised to search for Centauro signatures and long penetrating objects. Simulations show that CASTOR is well able to distinguish events with abnormal values of E(em)/E(had) or N(gamma)/N(ch). In addition simulations of the transition curves of Strangelets traversing the CASTOR calorimeter show long penetration and many-maxima structure such as observed in cosmic ray events.

Rheological properties of the interfacial layers of gelatins chemically modified with N-hydroxysuccinimide ester of caprylic acid (the degree of modification is 10, 30, and 85%) are studied. Interfacial layers are spontaneously formed at the aqueous gelatin solution–toluene interface. Rheological characteristics (yield strength, modulus of elastic deformation, Schwedoff and Bingham viscosities) increase in proportion to the degree of modification (hydrophobization) of gelatin.