Роль нових форм організації наукових досліджень у підвищенні інноваційного потенціалу НАН України

Здійснено порівняльний аналіз інноваційних розробок учених НАН України, частина яких перевершує показники зарубіжних або не має відповідних аналогів у світі, а також розглянуто значення нових форм організації наукових досліджень. Запропоновано першочергові заходи для підвищення ролі науки в інноваційному розвитку суспільства.Осуществлен сравнительный анализ инновационных разработок ученых НАН Украины, часть которых превосходит показатели зарубежных или не имеет соответствующих аналогов в мире, а также рассмотрено значение новых форм организации научных исследований. Предложены первоочередные меры по повышению роли науки в инновационном развитии общества.The comparative analysis of innovative developments of scientists of NAS of Ukraine, part of which excels foreign indexes or does not have proper analogues in the world is carried out. Value of new forms of scientific researche organization is determined. Primary measures are offered for the increase of science role in innovative development of society

Coverage and Disruption of Phospholipid Membranes by Oxide Nanoparticles

We studied the interactions of silica and titanium dioxide nanoparticles with phospholipid membranes and show how electrostatics plays an important role. For this, we systematically varied the charge density of both the membranes by changing their lipid composition and the oxide particles by changing the pH. For the silica nanoparticles, results from our recently presented fluorescence vesicle leakage assay are combined with data on particle adsorption onto supported lipid bilayers obtained by optical reflectometry. Because of the strong tendency of the TiO₂ nanoparticles to aggregate, the interaction of these particles with the bilayer was studied only in the leakage assay. Self-consistent field (SCF) modeling was applied to interpret the results on a molecular level. At low charge densities of either the silica nanoparticles or the lipid bilayers, no electrostatic barrier to adsorption exists. However, the adsorption rate and adsorbed amounts drop with increasing (negative) charge densities on particles and membranes because of electric double-layer repulsion, which is confirmed by the effect of the ionic strength. SCF calculations show that charged particles change the structure of lipid bilayers by a reorientation of a fraction of the zwitterionic phosphatidylcholine (PC) headgroups. This explains the affinity of the silica particles for pure PC lipid layers, even at relatively high particle charge densities. Particle adsorption does not always lead to the disruption of the membrane integrity, as is clear from a comparison of the leakage and adsorption data for the silica particles. The attraction should be strong enough, and in line with this, we found that for positively charged TiO₂ particles vesicle disruption increases with increasing negative charge density on the membranes. Our results may be extrapolated to a broader range of oxide nanoparticles and ultimately may be used for establishing more accurate nanoparticle toxicity assessments and drug-delivery systems

Interfacial Tension and Wettability in Water–Carbon Dioxide Systems: Experiments and Self-consistent Field Modeling

This paper presents experimental and modeling results on water–CO₂ interfacial tension (IFT) together with wettability studies of water on both hydrophilic and hydrophobic surfaces immersed in CO₂. CO₂–water interfacial tension (IFT) measurements showed that the IFT decreased with increasing pressure and the negative slopes of IFT–pressure isotherms decreased with increasing temperature. Water contact angle on a cellulose surface (hydrophilic) immersed in CO₂ increased with pressure, whereas the water contact angle on a hydrophobic surface such as hexamethyl disilazane (HMDS) coated silicon surface was almost independent of pressure. These experimental findings were augmented by modeling using the self-consistent field theory. The theory applies the lattice discretization scheme of Scheutjens and Fleer, with a discretization length close to the size of the molecules. In line with this we have implemented a primitive molecular model, with just small variations in the molar volume. The theory makes use of the Bragg-Williams approximation and has binary Flory–Huggins interaction parameters (FH) between CO₂, water, and free volume. Using this model, we generated the complete IFT–pressure isotherms at various temperatures, which coincided well with the trends reported in literature, that is, the water–CO₂ interfacial tension decreased with increasing pressure for pressures ≤100 bar and became independent of pressure >100 bar. The transition point occurred at higher pressures with increasing temperature. At three-phase coexistence (water–CO₂–free volume) and at the water–vapor interface (water–free volume), we always found the CO₂ phase in between the water-rich and free volume-rich phases. This means that for the conditions studied, the water–vapor interface is always wet by CO₂ and there are no signs of a nearby wetting transition. Calculation of the water contact angle on a solid surface was based on the computed adsorption isotherms of water from a vapor or from a pressurized CO₂-rich phase and analysis of surface pressures at water–vapor or water–CO₂ coexistence. The results matched reasonably well with the experimental contact angle data. Besides, we also computed the volume fraction profiles of the CO₂, H₂O, and the <i>V</i> phase, from which the preferential adsorption of CO₂ near the hydrophilic surface was deduced

Impact of Macromolecular Architecture on Bending Rigidity of Dendronized Surfaces

Nanomechanical properties of natural and artificial nanomembranes can be strongly affected by anchored or tethered macromolecules. The intermolecular interactions in polymeric layers give rise to so-called induced bending rigidity which complements the bare rigidity of the membrane. Using analytical mean-field theory, we explore how macromolecular architecture of tethered polymers affects the bending rigidities of the polymer-decorated membranes. The developed theory enables us to consider explicitly various polymer architectures including regular dendrons, Ψ-shaped, star- and comblike macromolecules as well as macrocycles. Numerical self-consistent field computations for selected (regular dendritic) topology complement the analytical theory and support its predictions. We consider both cases of (i) quenched symmetric distribution of tethered molecules on both sides of the membrane and (ii) annealing distribution in which the tethered polymers can relocate from the concave to the convex side of the membrane upon bending. We demonstrate that at a given surface coverage an increase in the degree of branching or cyclization leads to the decrease in the induced bending rigidity. Relocation of the tethered molecules from concave to convex surfaces leads to the additional decrease in polymer contribution to the membrane bending rigidity. In the latter case, a decrease in configurational entropy due to this redistributions substantially contributes to the bending rigidity

Adhesion and Friction Properties of Polymer Brushes: Fluoro versus Nonfluoro Polymer Brushes at Varying Thickness

A series of different thicknesses of fluoro poly­(2,2,2-trifluoroethyl methacrylate) and its analogous nonfluoro poly­(ethyl methacrylate) polymer brushes were prepared via surface-initiated ATRP (SI-ATRP) on Si(111) surfaces. The thiol-yne click reaction was used to immobilize the SI-ATRP initiator with a high surface coverage, in order to achieve denser polymer brushes (grafting density from ∼0.1 to 0.8 chains/nm²). All polymer brushes were characterized by static water contact angle measurements, infrared absorption reflection spectroscopy, and X-ray photoelectron spectroscopy. Adhesion and friction force measurements were conducted with silica colloidal probe atomic force microscopy (CP-AFM) under ambient and dry (argon) conditions. The fluoro poly­(2,2,2-trifluoroethyl methacrylate) polymer showed a decrease in adhesion and friction with increasing thickness. The analogous nonfluoro poly­(ethyl methacrylate) polymer brushes showed high adhesion and friction under ambient conditions. Friction coefficients down to 0.0057 (ambient conditions) and 0.0031 (dry argon) were obtained for poly­(2,2,2-trifluoroethyl methacrylate) polymer brushes with 140 nm thickness, which are the lowest among these types of polymer brushes

Impact of Macromolecular Architecture on Bending Rigidity of Dendronized Surfaces

Nanomechanical properties of natural and artificial nanomembranes can be strongly affected by anchored or tethered macromolecules. The intermolecular interactions in polymeric layers give rise to so-called induced bending rigidity which complements the bare rigidity of the membrane. Using analytical mean-field theory, we explore how macromolecular architecture of tethered polymers affects the bending rigidities of the polymer-decorated membranes. The developed theory enables us to consider explicitly various polymer architectures including regular dendrons, Ψ-shaped, star- and comblike macromolecules as well as macrocycles. Numerical self-consistent field computations for selected (regular dendritic) topology complement the analytical theory and support its predictions. We consider both cases of (i) quenched symmetric distribution of tethered molecules on both sides of the membrane and (ii) annealing distribution in which the tethered polymers can relocate from the concave to the convex side of the membrane upon bending. We demonstrate that at a given surface coverage an increase in the degree of branching or cyclization leads to the decrease in the induced bending rigidity. Relocation of the tethered molecules from concave to convex surfaces leads to the additional decrease in polymer contribution to the membrane bending rigidity. In the latter case, a decrease in configurational entropy due to this redistributions substantially contributes to the bending rigidity