# Yerevan State University

• Yerevan, Armenia
Recent publications
The detailed study of the effect of dimethylsulfoxide (or diethylsulfoxide) on interaction between methylene blue (MB) and calf thymus DNA was performed at 293.15 K using steady-state fluorescence quenching and fluorescence polarization. The combination of steady-state fluorescence quenching and fluorescence polarization reveal the main binding modes at different concentrations of DNA and the effect of sulfoxides on binding mechanism. For comparison, the other polar solvents such as N,N-dimethyl formamide and acetonitrile were used. From Stern–Volmer equation, the values of binding constant and standard Gibbs free energy change were determined. At low concentrations of DNA with addition of various organic cosolvents, the binding constant of DNA–MB complex decreases indicating that hydrogen bonds are predominant, and thus, the main binding mode is groove binding. At high concentrations of DNA, the binding mechanism changes and intercalation becomes the main binding mode in all solutions. Addition of cosolvents distorts the groove binding and, as a result, weakens the intercalation between MB and base pairs of double-stranded DNA.
The article examines the development of Russian-Turkish relations over the past 30 years, the main aspects of geopolitical relations and, in particular, the conﬂicts in the South Caucasus and adjacent regions. The authors believe that the key ones are the two Karabakh wars, the Georgian-Abkhazian conﬂict and the fve-day Georgian-South Ossetian war, as well as the Ukrainian crisis, the Libyan and Syrian conﬂicts, in which Moscow and Ankara have different interests. The new confguration of forces in the South Caucasus will largely depend on the outcome of the resolution of these conﬂicts. The authors identify the main patterns in the development of bilateral Russian-Turkish relations, which are characterized by a combination of confrontation, competition and cooperation. The article was based on the results of a scientifc discussion held at the National Communications Development Research Institution (NIIRC), Moscow, Russia in 2022.
Global warming linked to the industrial emissions of greenhouse gases may be the end of mankind unless it is adequately and timely handled. To prevent irreversible changes to the climate of the Earth, numerous research groups are striving to develop robust CO2 sorbents. Dialkyl carbonates (DACs) and CO2 exhibit obvious chemical similarities in their structure and properties. The degrees of oxidation of all atoms composing DACs and CO2 are identical resulting in very similar nucleophilicities and electrophilicities of all interaction centers. While both compounds possess relatively high partial atomic charges on their polar moieties, the molecular geometries prevent tight binding of the head groups. The computed DAC-DAC binding energies are ∼40 kJ mol-1, whereas the effect of the alkyl chain length is marginal. The phase transition points and shear viscosities of DACs are very low. We herein hypothesize and numerically rationalize that DACs represent noteworthy physical sorbents for CO2 thanks to the similar sorbent-CO2 and sorbent-sorbent interaction energies. By reporting in silico-derived sorption thermodynamics at various conditions, spectral and structural properties, and experimentally derived CO2 capacities and recyclabilities, we highlight the mutual affinity of DACs and CO2. Indeed, the experimentally determined CO2 sorption capacity of 0.88 mol% (diethyl carbonate) at 278.15 K and 30 bar is competitive. The unprecedentedly low DAC-CO2 binding energies, ∼14 kJ mol-1, suggest a low-cost desorption process and outstanding recyclability of the sorbent. We also note that DACs possessing long alkyl chains (butyl, hexyl, octyl) exhibit negligible volatilities, while preserving the liquid aggregate state over a practically important temperature range. The reported results may foster the development of a new class of CO2 scavengers with possibly quite peculiar characteristics.
To reveal the effect of DNA- or RNA-specific low-molecular compounds on cellular processes on the molecular level, we have carried out the studies with the application of spectroscopic methods. It is necessary for the understanding of structural-functional properties of nucleic acids in cell. In this work the interaction of DNA-specific thiazine dye methylene blue (MB) with synthetic polynucleotides poly(rA) and poly(rU) was studied. The interaction of MB with synthetic polyribonucleotides poly(rA) and poly(rU) was examined in the solution with high ionic strength in a wide phosphate-to-dye (P/D) range, using the absorption and fluorescence spectroscopies, as well as the fluorescence 2D spectra and 3D spectra analyses were given. Values of the fluorescence quenching constants for the complexes of MB with poly(rA) and poly(rU) were calculated (KSV is the Stern-Volmer quenching constant). Two different modes of MB binding to single-stranded (ss-) poly(rA) and poly(rU) and to their hybrid double-stranded (ds-) structure – poly(rA)-poly(rU) were identified. This ligand binds to ss-poly(rA) and poly(rA)-poly(rU) by semi-intercalation and electrostatic modes, but to ss-poly(rU) the prevailing mode is the electrostatic interaction. Communicated by Ramaswamy H. Sarma
During the last years, giant optical anisotropy has demonstrated its paramount importance for light manipulation. In spite of recent advances in the field, the achievement of continuous tunability of optical anisotropy remains an outstanding challenge. Here, we present a solution to the problem through the chemical alteration of halogen atoms in single-crystal halide perovskites. As a result, we manage to continually modify the optical anisotropy by 0.14. We also discover that the halide perovskite can demonstrate optical anisotropy up to 0.6 in the visible range─the largest value among non-van der Waals materials. Moreover, our results reveal that this anisotropy could be in-plane and out-of-plane depending on perovskite shape─rectangular and square. As a practical demonstration, we have created perovskite anisotropic nanowaveguides and shown a significant impact of anisotropy on high-order guiding modes. These findings pave the way for halide perovskites as a next-generation platform for tunable anisotropic photonics.
This paper examines Azerbaijan’s decision to go to war in Nagorno-Karabakh in 2020. It aims to unveil the lessons Azerbaijan learned from the reaction of major regional actors in the South Caucasus to rising tensions in Armenian–Azerbaijani relations from the mid-2000s to the 2020 July border crisis. The paper argues that the consistent unresponsiveness of the international community emboldened Azerbaijan to proceed with its war preparations. It shows that Azerbaijan perceived the attitude of regional powers as inability and/or reluctance to interfere in the conflict, and this created a permissive environment for an all-out war.
We elucidate grapevine evolution and domestication histories with 3525 cultivated and wild accessions worldwide. In the Pleistocene, harsh climate drove the separation of wild grape ecotypes caused by continuous habitat fragmentation. Then, domestication occurred concurrently about 11,000 years ago in Western Asia and the Caucasus to yield table and wine grapevines. The Western Asia domesticates dispersed into Europe with early farmers, introgressed with ancient wild western ecotypes, and subsequently diversified along human migration trails into muscat and unique western wine grape ancestries by the late Neolithic. Analyses of domestication traits also reveal new insights into selection for berry palatability, hermaphroditism, muscat flavor, and berry skin color. These data demonstrate the role of the grapevines in the early inception of agriculture across Eurasia.
Cancer continues to be a leading cause of death worldwide, making the development of new treatment methods crucial in the fight against it. With cancer incidence rates increasing worldwide, ongoing research must focus on identifying new and effective ways to prevent and treat the disease. The combination of herbal extracts with chemotherapeutic agents has gained much interest as a novel strategy to combat cancer. Rumex obtusifolius L. is a wild plant known for its medicinal properties and is widely distributed worldwide. Our preclinical evaluations suggested that R. obtusifolius seed extracts possessed cancer-inhibiting properties and we also evaluated the beneficial effects of the arginase inhibitor NG-hydroxy-nor-L-arginine and nitric oxide inhibitor NG-nitro-L-arginine methyl ester in the treatment of breast cancer. The current study aimed to combine these observations and evaluate the antioxidant and antitumor properties of R. obtusifolius extracts alone and in combination with the arginase and nitric oxide synthase inhibitors. Metabolic characterization of the plant extract using a liquid chromatography/high-resolution mass spectrometry advanced system revealed the presence of 240 phenolic compounds many of which possess anticancer properties, according to the literature. In vitro studies revealed a significant cytotoxic effect of the R. obtusifolius extracts on the human colon (HT29) and breast cancer (MCF-7) cell lines. Thus, a new treatment approach of combining R. obtusifolius bioactive phytochemicals with the arginase and nitric oxide synthase inhibitors NG-nitro-L-arginine methyl ester and/or NG-hydroxy-nor-L-arginine, respectively, was proposed and could potentially be an effective way to treat breast cancer. Indeed, these combinations showed immunostimulatory, antiproliferative, antioxidant, anti-inflammatory, and antiangiogenic properties in a rat breast cancer model.
The paper studies families of two-parameter Bergman type operators Tβ,λ,Sβ,λ,Φβ,δ in mixed norm and Besov spaces on the unit ball of Rn. Motivated by a series of papers by Choe et al., we extend estimation theorems for harmonic reproducing kernels. This enables us to obtain boundedness of operators Tβ,λ,Sβ,λ,Φβ,δ on mixed norm and Besov spaces for appropriate parameters. A necessary and sufficient condition is found for Tβ,λ and Sβ,λ to be bounded on mixed norm spaces L(p,q,α). For non-positive α, Bergman projection Tβ,0 continuously maps mixed norm space L(p,q,α) onto corresponding Besov space. Furthermore, a new operator Φβ,δ of Bergman type is found that projects Besov space of smooth functions onto its harmonic subspace.
We consider a class of two-dimensional integral equations with noncompact monotone Hammerstein operators and concave nonlinearity. We prove a constructive theorem on the existence and uniqueness of a nontrivial nonnegative bounded solution and study the asymptotic behavior of the solution at infinity. Some examples of kernels and nonlinearity are given.
Background: North American bat populations have suffered severe declines over the last decade due to the Pseudogymnoascus destructans fungus infection. The skin disease associated with this causative agent, known as white-nose syndrome (WNS), is specific to bats hibernating in temperate regions. As cultured fungal isolates are required for epidemiological and phylogeographical studies, the purpose of the present work was to compare the efficacy and reliability of different culture approaches based on either skin swabs or wing membrane tissue biopsies for obtaining viable fungal isolates of P. destructans. Results: In total, we collected and analysed 69 fungal and 65 bacterial skin swabs and 51 wing membrane tissue biopsies from three bat species in the Czech Republic, Poland and the Republic of Armenia. From these, we obtained 12 viable P. destructans culture isolates. Conclusions: Our results indicated that the efficacy of cultures based on wing membrane biopsies were significantly higher. Cultivable samples tended to be based on collections from bats with lower body surface temperature and higher counts of UV-visualised lesions. While cultures based on both skin swabs and wing membrane tissue biopsies can be utilised for monitoring and surveillance of P. destructans in bat populations, wing membrane biopsies guided by UV light for skin lesions proved higher efficacy. Interactions between bacteria on the host's skin also appear to play an important role.
The article presents the results of the seven-year study on the state of arable lands and wastewaters in the districts of mining enterprises in Armenia. An assessment of the ecological and toxicological state of wastewaters and contaminated areas was carried out. Methods for their purification are proposed aimed at their further use and obtainment of environmentally safe agricultural products. An area of about 0.5 ha, next to the rural community of Syunik in southern Armenia, has been polluted for many years by mining sludges from the nearest mine watertight cofferdam of the Zangezur copper-molybdenum combine. Activities have been carried out to clean up the soil in this area. After plowing, soil improvers (zeolite, bentonite, and manure) were introduced into the soil. On-site treatments, soil tillage, and the introduction of soil improvers into the soil was implemented in late autumn. Soil and plant samples were taken to determine the content of heavy metals (Cu, Zn, Pb, Co, Mo, Ni). In the following spring, the area was planted with potatoes, eggplant, and peas. A rather high yield was obtained. Analysis of plant samples showed that the content of heavy metals does not exceed the permissible level of the international food safety standard. At the same time, soil studies were carried out in the adjacent areas of the Sotk mine, located to the southeast of Lake Sevan. It was revealed that due to the increase in the volume of the mining industry and the amount of rock dumps, the organoleptic and chemical indicators of the waters of the Sotk and Masrik rivers deteriorated. Compared to the previous decade, the amounts of suspended particles per 1 L of water have increased by 210…317.0%, in the waters of Sotk—by 32.1 mg/L, and in the waters of Masrik—by 13.2 mg/L. The same tendency is observed regarding the amounts of nitrates, sulfates, and hydrogen index, which is mainly due to the chemical composition of rocks. They contain a large amount of Ca, K, Na, Mg, etc. This trend is especially noticeable along the rivers, where intensive agriculture, primarily livestock farming is carried out. The material of the work solves a complex of environmental and economic problems. It is aimed at ensuring environmental safety, improving the ecological and resource properties of soils, increasing the productivity of cultural phytocenoses and the sanitary and hygienic quality of food products.
In this paper, we investigate the problem of band gaps for flexural waves in a beam with periodically attached piezoelectric patches and internal hinges for the purpose of vibration energy harvesting. Based on Euler–Bernoulli beam theory, general solutions of the finite length periodic beam for two topological systems (beam with patches, beam with patches and internal hinges) are obtained using the transfer matrix method. By applying the Floquet theory, the explicit expressions are derived defining the band gap structure. The corresponding band gap dispersion curves are plotted. The innovation of this paper is the results concerning widening of the resonant bandwidth of a piezoelectric harvester based on phononic band gaps generated by internal hinges, not by patches.
In the twenty-first century, changing global power equations are impacting the dynamics of foreign and security policy choices of small states, as they seek to develop alliances and partnerships to offset their geopolitical and geo-economic vulnerabilities. In this context, Armenia’s security orientation is largely seen as consistently intertwined with Russia even after independence. Armenia has also attempted to develop a “normative alliance” with the European Union, relying mostly on its special relations with France. In recent years, various factors including domestic politics, deficit of security, and Russian dominance have led to a gradual re-orientation in the Armenian alliance trajectory towards more multilateral partnerships indicating a tendency towards “hedging” alliances. Conceptualizing from a theoretical foundation relating to small-state alliance options, this paper presents a case for Armenia-India strategic partnerships, given the historical and cultural ties between the two nations and the rapid growth of India as an emergent giant in the multipolar world. In this context of strategic analysis, the Georgia-Armenia-Iran corridor has a potential of vital geo-economic and geopolitical axis for India as well as for Russia, the EU, and China. The position of Armenia with its “both… and” integration approach, approximation with the EU, and strategic partnership with Russia has proved to be insufficient in security issues; however, the friendly disposition of a rising power, such as India, leaves Armenia with the capacity to diversify its security as a local civilizational and geo-economic connector.
Установлено, что если $\{f_n(t)\}_{n=-m+2}^{\infty }$ - ортонормированная в $L^2[0,1]$ система, состоящая из сплайнов порядка $m$ с двоично-рациональными узлами и $f(t)$ - п.в. конечная измеримая функция, то, во-первых, существует ряд по этой системе, который п.в. абсолютно сходится к этой функции, и, во-вторых, для любого $\varepsilon >0$ функцию $f(t)$ можно изменить на множестве меры меньше $\varepsilon$ так, чтобы вновь полученная функция имела равномерно абсолютно сходящийся ряд Фурье по этой системе.
LARES 2, successfully launched on July 13, 2022, is a new generation laser-ranged satellite. LARES is an acronym for LAser RElativity Satellite. The first LARES satellite was successfully launched on February 13, 2012 with the ESA-ASI-AVIO launch vehicle VEGA. LARES 2 was injected with extremely high precision onto a high-altitude orbit at about 5900 km altitude with the new ESA-ASI-AVIO launch vehicle VEGA C. Laser-ranged satellites have many applications, including to test Einstein’s theory of general relativity. The main general relativistic phenomenon that LARES 2 will test with high accuracy is the dragging of inertial frames, or frame-dragging. It will also test other aspects and principles of fundamental physics and general relativity, such as the weak equivalence principle at the foundation of viable gravitational theories. Frame-dragging is the name Einstein himself gave in 1913 to an intriguing phenomenon of general relativity which implies that a current of mass-energy, such as the rotation of a body, will generate spacetime curvature. Frame-dragging has a key role in high energy astrophysics, e.g., in the generation of gravitational waves by the collision of two black holes to form a rotating black hole. Frame-dragging by the rotating Earth was measured to a few percent accuracy by combining the data of the satellites LARES, LAGEOS and LAGEOS 2 (Ciufolini et al. in Eur Phys J C 79:872, 2019). LARES 2, thanks to its extremely high injection precision, is projected to improve the test of frame-dragging by at least an order of magnitude. LARES 2 has also relevant applications in space geodesy and geodynamics, e.g., in the study of the shape of the Earth and in the determination of the International Terrestrial Reference Frame (ITRF) by improving the determination of the Earth center of mass and by contributing to a better determination of its rotation axis.
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• Chair of Applied electrodynamics end modeling
• Faculty of Physics
• Department of Biochemistry Microbiology and Biotechnology
• Faculty of Informatics and Applied Mathematics