In March this year, the scientific community celebrates the 90th anniversary of the birth of Ivan Petrovych Dzyub, a well-known Ukrainian theoretical physicist, the first chairman of the Higher Attestation Commission of independent Ukraine, a diplomat, a well-known interpreter and public figure, a member of the National Union of Writers of Ukraine, the laureate of the State Prize of the Ukrainian SSR in science and engineering, the laureate of the Maksym Rylskyi Prize, and a knight of the Order of the Rising Sun, Gold Rays with Rosette (Japan).

The atomic structure, stoichiometry and electron work function of Ce + O films co-adsorbed on Mo(112) were studied by low-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and contact potential difference (CPD) methods. The films with a significant predominance of one major species show the structure characteristic of the main component, which remains stable up to 15−50% of the minor species content. We report the c(4 × 4) and c(2 × 6) superstructures for Ce + O films with single layer Ce coverage as well as c(4 × 6) and (2 × 2) for double layer Ce coverage. They are exclusively specific to the (Ce + O)/Mo(112) system and have not been previously observed neither for cerium oxides nor pure cerium/pure oxygen adfilms. No noticeable electron work function change was detected due to oxygen addition to the Ce/Mo(112) films. Both oxygen-enriched and oxygen-depleted (Ce + O) films show similar typical electropositive properties.

Показано, що високовпорядковані моношарові плівки гексадецилборної кислоти CH3–(CH2)15–B(OH)2 можуть бути отриманіна базисній площині високоорієнтованого піролітичного графіту шляхом нанесення розчину кислоти в n-тетрадекані n-C14H30 при кімнатній температурі. За допомогою сканувального тунельного мікроскопа (СТМ) встановлено, що моношари мають ламелеподібну структуру, в якій кожна ламель сформована парами (димерами) молекул гексадецилборної кислоти. Асоціація молекул у димери здійснюється завдяки взаємодії між B(OH)2-групами. Виявлено також, що молекули розчинника n-C14H30, перебуваючи при температурі, значно вищій, ніж температура поверхневої кристалізації моношару тетрадекану на графіті, можуть адсорбуватись спільно з молекулами кислоти. Співадсорбцію молекул розчинника можна пояснити специфікою взаємної геометрії поверхні підкладки і димерів гексадецилборної кислоти.

•A set of ordered structures are found in submonolayer Ce/Mo(112) films doped by O.•Self-ordering of the p(2 × 1) Ce/Mo(112) film into wide periodic stripes is detected.•Mesoscopic self-ordering in the adlayer is activated by annealing at T > 1200 K.Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), contact potential difference (CPD) measurements and density functional theory (DFT) calculations have been used to study submonolayer adsorption of Ce on the molybdenum (112) surface. Oxygen impurities ranging from 1 to 25 atomic % within different Ce deposits were detected by AES in our work. Depositing various amounts of Ce (below and above a single monolayer) on Mo(112) at room temperature produced only a highly defective adlayer with a p(2  ×  1) structure, which is specific of coverage θ = 0.5. However, the DFT simulations of a pure Ce/Mo(112) system clearly pointed to a c(2  ×  2) adlayer structure as energetically preferable at θ = 0.5. This discrepancy has been attributed to the presence of oxygen in the Ce deposit, which substantially affects the properties of the Ce-Mo(112) system. Annealing the samples at temperatures Ta ≤ 1450 K improved the degree of ordering in the p(2  ×  1) adlayer, but also led to significant surface structure changes. In particular, incommensurate c(8  ×  4) and c(1.44  ×  2) structures were found at coverages of 0.63 and 0.7, respectively. In a broad coverage range of θ = 0.1−0.45, annealing at Ta ≥ 1200 K gave rise to complex LEED patterns which correspond to p(2  ×  1) and (n  ×  1) structures, with n ≥ 24 being coverage dependent. This has been ascribed to the formation of p(2  ×  1) striped Ce domains arranged with a mesoscopic 1D periodicity amounting to dozens of substrate lattice spacings along the [111̅] direction (about 65 Ǻ at n =24). The self-organization of such domains is discussed in terms of strain-induced and electrostatic (contact potential) driving forces.

Поверхні — всюдисущі межі поділу різних середовищ

Atomic force microscopy (AFM) is widely used for structural characterization of 2D materials. We report here on the appearance of linear pseudo-structures of subnanometer height ('nanotracks'), observed in AFM images of 2D-nanoparticles of graphene, MoS2, WS2, BN, synthesized by the mechanochemical technique and deposited from dispersions on the mica surface. It is stated that the nanotracks appear as a result of nanoparticle displacement on the surface under the influence of the AFM tip during scanning. The appearance of the nanotracks is caused by a high relative concentration of monolayer nanoparticles in the prepared dispersions; their bulk aggregation; subsequent destruction of the aggregates by the AFM probe with formation of the nanoparticles weakly bound to the substrate. A method is proposed how to distinguish monolithic particles from granulated aggregates, as well as a technique to prevent their displacement during measurements. The possibility is considered of using AFM to develop effective nanolubricants and provide their precise nanoscale deposition on the specified surface areas.

Cisplatin (Cis-Pt) is the cytotoxic agent widely used against tumors of various origin, but its therapeutic efficiency is substantially limited by a non-selective effect and high toxicity. Conjugation of Cis-Pt with nanocarriers is thought to be one option to enable drug targeting. The aim of this study was to estimate toxic effects of the nanocomplex formed by noncovalent interaction of C60 fullerene with Cis-Pt against Lewis lung carcinoma (LLC) cells in comparison with free drug. Scanning tunneling microscopy showed that the minimum size of C60–Cis-Pt nanoparticles in aqueous colloid solution was 1.1 nm whereas that of C60 fullerene was 0.72 nm, thus confirming formation of the nanocomplex. The cytotoxic effect of C60–Cis-Pt nanocomplex against LLC cells was shown to be higher with IC50 values 3.3 and 4.5 times lower at 48 h and 72 h, respectively, as compared to the free drug. 12.5 µM Cis-Pt had no effect on LLC cell viability and morphology while C60–Cis-Pt nanocomplex in Cis-Pt-equivalent concentration substantially decreased the cell viability, impaired their shape and adhesion, inhibited migration and induced accumulation in proapoptotic subG1 phase. Apoptosis induced by the C60–Cis-Pt nanocomplex was confirmed by caspase 3/7 activation and externalization of phosphatidylserine on the outer surface of LLC cells with the double Annexin V-FITC/PI staining. We assume that C60 fullerene as a component of the C60–Cis-Pt nanocomplex promoted Cis-Pt entry and intracellular accumulation thus contributing to intensification of the drug’s toxic effect against lung cancer cells.

Introduction. The establishment of regularities of the microcontact interaction in the friction interface formed by two moving bodies is an important step towards the creation of new classes of materials with predefined physicochemical properties. The relative motion of interacting surfaces inevitably results in wearing contact areas (microcontacts) of these surfaces, i.e. leads to the formation of fragments caused by destruction of more elastic material. Problem Statement. The destruction of the interface decreases significantly by applying lubricant films to the contact area. In the case of dry friction (no lubricant), the description of the contact area is a practically solved problem (the Hertz and the Johnson-Kendal-Roberts contact theories), while the presence of lubricant complicates significantly this problem, because one shall consider the theological component of friction and the interaction of interfaces. In addition, the overwhelming majority of tribological studies were carried out using imperfect (rough) surfaces and lubricant films with uncertain component composition, thickness, and structure. Purpose. To establish the influence of the structure of self-assembling n-alkanes monolayers on their tribological properties in the frictional interface. Materials and Methods. The atomically flat surface of gold and one-component monolayer films of n-alkanes (C-n/(2n)(+2) n = 14, 16, 48, 50, 60). are used as materials. The scanning tunneling microscopy method is used to establish the structure of self-assembled monolayers on the gold surface as well as to control their destruction before and after the tribological measurements. The kinetic coefficient of friction mu(ko) of interfaces have been studied using a magnetic levitation tribometer. Results. The nonmonotonic dependence of kinetic friction coefficient mu(ko) on the length of n-alkane molecule has been experimentally established. Conclusions. The kinetic friction coefficient mu(ko) has been established to abnormally decrease for the n-alkanes with "magic length" (n times 16).

A herbal alkaloid Berberine (Ber), used for centuries in Ayurvedic, Chinese, Middle-Eastern, and native American folk medicines, is nowadays proved to function as a safe anticancer agent. Yet, its poor water solubility, stability, and bioavailability hinder clinical application. In this study, we have explored a nanosized carbon nanoparticle-C60 fullerene (C60)-for optimized Ber delivery into leukemic cells. Water dispersions of noncovalent C60-Ber nanocomplexes in the 1:2, 1:1, and 2:1 molar ratios were prepared. UV-Vis spectroscopy, dynamic light scattering (DLS), and atomic force microscopy (AFM) evidenced a complexation of the Ber cation with the negatively charged C60 molecule. The computer simulation showed that π-stacking dominates in Ber and C60 binding in an aqueous solution. Complexation with C60 was found to promote Ber intracellular uptake. By increasing C60 concentration, the C60-Ber nanocomplexes exhibited higher antiproliferative potential towards CCRF-CEM cells, in accordance with the following order: free Ber < 1:2 < 1:1 < 2:1 (the most toxic). The activation of caspase 3/7 and accumulation in the sub-G1 phase of CCRF-CEM cells treated with C60-Ber nanocomplexes evidenced apoptosis induction. Thus, this study indicates that the fast and easy noncovalent complexation of alkaloid Ber with C60 improved its in vitro efficiency against cancer cells.

•Kinetics of oxygen adsorption and Be oxidation on the Be/Mo(1 1 2) surface was studied.•2D honeycomb structures of BeO monolayer and nanoribbons on Mo(1 1 2) have been obtained.•Adsorbed BeO monolayers on Be/Mo(1 1 2) and Mo(1 1 2) decrease the work function.We have used Auger electron spectroscopy, low-energy electron diffraction, contact potential difference measurements and the density functional theory calculations to study oxygen adsorption on the supermonolayer Be/Mo(1 1 2) films as well as their composition and structure transformations under annealing. Adsorption of oxygen on Be–Mo(1 1 2) results in the synthesis of BeO at room temperature, and the film becomes a two-component system consisting of oxidized and non-oxidized Be. Under annealing in the temperature range 1100–1250 K, the non-oxidized Be desorbs and only BeO remains on the surface up to 1500−1600 K. Desorption of non-oxidized Be results in BeO ordering to a commensurate structure (1 × 1) identified as a 2D honeycomb nanosheet. Formation of overlayers depleted of Be and O is observed during desorption of BeO. A model of honeycomb nanoribbons is suggested for their structure. Adsorbed BeO monolayers were found to reduce the work function of the Mo(1 1 2) and Be/Mo(1 1 2) surfaces.

We developed a new magnetic levitation tribometer (MLT) to study point-contact friction via pendulum method. The device allows us to carry out fast and accurate point-contact measurement of friction between a pair of materials. The MTL parameters were found with the help of test experiments with the steel ball / glass plate pair. The friction coefficient values are coherent with the results known in the literature (Serway and Beichner in Physics for scientists and engineers, 5th edn, Saunders College Publishing, Orlando, 2000). The proposed MLT technique at loads lower than \(10^{-3}\) N is very promising for non-destructive investigation of frictional properties of organic monolayers.

НАЦІОНАЛЬНОЇ АКАДЕМІЇ НАУК УКРАЇНИ ФІЗИКАПлоща контакту двох поверхонь, їх шорсткість та шар змащувального матеріалу між ними відіграють ключову роль у визначенні трибологічних параметрів досліджуваної системи.Широкий спектр експериментальних методів дає змогу досліджувати вплив одного або декількох факторів на процес тертя.Фрикційна, сканувальна і атомно-силова мікроскопії дозволяють ідентифікувати дефекти інтерфейсів тертя на атомарному рівні [1][2][3].У той час як методи похилої площини або поєднання похилої площини і маятника дозволяють вико

Amyloid fibrils are insoluble protein aggregates whose accumulation in cells and tissues is connected with a range of pathological diseases. We studied the impact of 2 metal complexes (axially coordinated Hf phthalocyanine and iron (II) clathrochelate) on aggregation of insulin and lysozyme. For both proteins, the host-guest interaction with these compounds changes the kinetics of fibrillization and affects the morphology of final aggregates. The Hf phthalocyanine is a very efficient inhibitor of insulin fibrillization; in its presence, only very low amounts of fibrils with the diameters of 0.8 to 5nm and spherical aggregates were found. Effective concentration of fibrillization inhibition (IC50) was estimated to be 0.110.04M. The clathrochelate induced the formation of thin fibrils with the diameters of 0.8 to 2.5nm; IC50 was estimated as 20 +/- 9M. The lysozyme fibrillization remained quite intensive in the presence of the studied compounds; they induced the formation of long filaments (the length up to 2.5m, the diameters of 1.5-3.5nm). These fibrils noticeably differed from those of free lysozyme short linear species (the diameters of 3-5nm, the length up to 0.6m). Thinning and elongation of fibrils suggest that the metal complexes bind mainly to the grooves of protofilaments; this hinders the stacking of early aggregates or protofilaments together but does not hinder their growth. The image of the fibril separated into 2 protofilaments allows suggesting that the fibril formation occurs via the growth of the parallel protofilaments with their subsequent twisting in the fibril. The changes of the lysozyme intrinsic fluorescence indicate that both metal complexes interact with the protein during the stage of the fibrillar seeds formation.

We analyzed the Ge/Si(100) phase composition based on existing literature data and results obtained with high-resolution electron microscopy method. The research confirms formation of solid solutions Ge(Si) in the Ge film and the Si(Ge) in the Si (100) substrate, which are separated by a thin pseudomorphic layer. This conclusion can correctly interpret the phase composition of the heterostructure based on Ge and Si. An array of tips developing on the interface with the tip density of the order 10(14) m(-2) was visualized. The emission properties of the tips were studied, including electric field strength near their peaks reaching 10(9) V/m, which causes cold emission.

Using the scanning tunneling microscopy, it is found that the structural organization of n-alkane molecules n-CnH2n+2 (n = 10 divided by 50) on the reconstructed Au(111) surface varies nonmonotonically, as the length of a molecule changes. The nonmonotonic character of the adsorption reveals itself in the alternation of packing types, dependence of the monolayer stability on.., and modification of surface properties. In the framework of the proposed one-dimensional model, it is shown that the correlation between the structure of adsorbed monolayers and the length of molecules is caused by a mismatch between the periods of the alkyl chain and the Au(111) surface along the < 110 > direction. The one-end functionalization of n-alkane molecules due to the chemically active -SH (n-alkanethiols) or -COOH (n-acids) group is demonstrated to result in the formation of a brush-like structure with "vertical" geometry of the adsorption, in which the anchoring of molecules at the surface occurs owing to the formation of covalent bonds.

The electropositive (alkali, alkaline-earth, and rare-earth) atoms have low ionization energies and form strongly polar adsorption bonds with substrates that consist of elements from other groups of the periodic table. A substantial part of the electron density of their valence shells is transferred to the substrate, and the resulting dipole moment of the bond determines the peculiar characteristics of such adsorption systems. In particular, the electropositive atoms strongly modify surface properties, such as the work function, catalytic activity, surface band bending, plasmonic excitations, and so on. These properties can be controllably tailored by changing the concentration of adatoms within the first monolayer. The variety of 2D structures formed by electropositive adatoms allows exploration of phase transitions specific of low-dimensional systems, in particular their correlation with surface physicochemical processes.