Armenian National Academy of Sciences

About: Armenian National Academy of Sciences is a government organization based out in Yerevan, Armenia. It is known for research contribution in the topics: Population & Laser. The organization has 4090 authors who have published 4042 publications receiving 40828 citations. The organization is also known as: Armenian National Academy of Sciences & NAS RA.

Optimum Nutrition for Biosynthesis of Pharmaceutical Compounds in Celandine and Catmint Under Outside Hydroponic Conditions

Abstract: Several experiments were performed to improve the management of biosynthesis of some pharmaceutical compounds (alkaloids, essential oil, tannins, and vitamin C) of medicinal plants celandine poppy (Chelidonium majus L.) and lemon catmint (Nepeta cataria L. f. citriodora) under outside hydroponics of Ararat Valley of Armenia. It was found that growing media and nutrient solutions that differed in concentrations and ratios of nitrogen (N), phosphorus (P), and potassium (K) influenced various pharmaceutical compounds of these herbs. Celandine under hydroponics conditions (with high N at a ratio of N70P15K15 atom%) had an alkaloid content up to 1.53% (calculated in dry raw material), while under soil the content was no higher than 1.22%. The content of tannins in celandine was up to 7.58% in hydroponics and 5.76% in soil. The content of vitamin C was up to 131.67 mg/% when grown in hydroponics and 94.92 mg/% when grown in soil (based on fresh raw material). In catmint, the maximum content and yield o...

About the Aerothermoelastic Stability of Panels in Supersonic Flows

Abstract: This article provides new insights into the aerothermoelastic stability of thin plates. Particularly, the issue of loss of stability of an isotropic plate-strip of constant thickness immersed in a supersonic flow field and subjected to a variable temperature field through the thickness is examined. Using the basic principles of the theory of aerothermoelasticity of isotropic bodies, the theories of flexible panels, and the linear law of temperature field through the thickness of the panel, the stability equations and associated boundary conditions are obtained. As expected, the coefficients of the aerothermoelastic governing equations depend on the thermal load, and consequently the panel-flutter critical speed depends on temperature. The model takes into account quadratic and cubic aerodynamic non-linearities as well as cubic geometric non-linearities. Due to the inhomogeneity of the temperature field distribution across the thickness plate buckling instability occurs. This instability accounts for the d...

Collectins and host defence.

Abstract: The collectins are a small family of soluble oligomeric proteins containing collagenous regions and C-type lectin domains. They are related in structure and function to complement protein C1q, and to H-, L- and M-ficolins. In humans, the collectins mannose-binding lectin (MBL) and surfactant proteins A and D (SP-A, SP-D) have important roles in innate immunity. MBL occurs mainly in blood plasma and in the upper respiratory tract. It binds to neutral sugar arrays on microorganisms and acts as an opsonin either directly (by binding to cell-surface calreticulin) or indirectly by activating complement. MBL circulates in complex with any of three proteases, named MBL-associated serine proteases (MASPs)-1, -2 and -3. MBL-MASP-2 complexes activate complement, but the role of MBL-MASP-1 and MBL-MASP-3 complexes is not yet known. MBL deficiency occurs at high frequency, and is associated with susceptibility to infection, particularly in infants. SP-A and SP-D are most abundant in the lungs, and also bind to microorganisms and inhaled particulates, mainly by lectin-sugar interactions. They do not activate complement, but act as opsonins and agglutinators, and have additional effects on cellular regulation. Mice deficient in SP-A or SP-D are susceptible to lung infections, and SP-D-deficient mice develop an emphysema-like condition.

Quantum superposition states in third-harmonic generation

Abstract: We investigate numerically the distribution functions of photon number and phase in third-harmonic generation in the region of instability. It is shown that in this system the quantum superposition states for the third harmonic and fundamental mode can appear.

Photorefractivity of hafnium-doped congruent lithium-niobate crystals

Abstract: In this work we present an investigation principally aimed at determining the threshold in HfO/sub 2/ concentration above which no further reduction of photorefraction is obtained. The measurements are made by inducing photorefraction with a 532-nm laser beam on a set of congruent LN crystals doped with increasing HfO/sub 2/ concentration.