Frog skin active peptides (FSAP) as a highy effective antimicrobial agents

During last ten to fifteen years a considerable scientific attention has been paid to biologically active substances as known as frog skin active peptides (FSAP). These substances are naturally produced by many Amphibian organisms and could be found within skin secretion of most frog families, especially Ranidae. Biomolecules of that class possess extremely valuable properties: show high antimicrobial and antifungal activity - especially effective against multiresistant bacterial infections; act as protease inhibitors and components of an innate immune system; demonstrate relatively weak hemolytic activity. Such a combination makes frog skin active peptides a potential candi dates for drug development with possible application in therapy, traumatology, surgery, etc. In present paper an origin, classification, function as well as methods for determination of FSAP are summarized. It is underlined that Bulgarian region is definitely suitable for extensive FSAP investigations due to the naturally abundance of genus Rana species.Scripta Scientifica Medica 2009; 41(2): 195-200

The use of virtual machines in education institutions

The possibility of virtual machines are wide enough. They address many issues related to application compatibility and operating system, as well as the safe use of a personal computer, which in turn is important for educational institutions due to the rapid pace of development of information technologiesВозможности виртуальных машин достаточно широки. Они решают многие вопросы, связанные с совместимостью приложений и операционной системы, а так же с безопасным использованием персонального компьютера, что, в свою очередь, важно для образовательных учреждений в силу быстрых темпов развития информационных технологи

Didactic principles on the basis of use of virtual machines

This article describes the generally recognized didactic principles, considered the idea of the use of virtual machines in the educational process, as well as didactic principles underlying the use of virtual machinesВ данной статье рассмотрены общепризнанные дидактические принципы, рассмотрена идея о применении виртуальных машин в образовательном процессе, а также дидактические принципы, положенные в основу использования виртуальных маши

Using neural network for simulations to improve the quality of disease diagnosis: Technical aspects

Mathematical models are important for the processes of cognition and decision-making. They provide a concise representation of significant relationships in the description of objects and situations. Adding new relationships leads to narrowing the scope of applicability of the model. The formula is an example of a compressed description of a potentially infinite set of objects and situations. Knowledge processing is based on the use of mathematical methods. In this case, it is the most thorough, at least from the point of view of strict logic and consistent formalization. To process knowledge, we must present it in some form that is convenient for analysis. Thus, when analyzing data and knowledge, we do not use them directly, but their representations. Mathematical models of objects and phenomena are an effective way of representation. This is now the most powerful method of cognition of processes, objects and phenomena. Modeling is a special way of scientific research. A mathematical model of an object is a mathematical structure interpreted within a given domain. © 2020, World Academy of Research in Science and Engineering. All rights reserved

Strontium And Iron Substituted Lanthanum Nickelate As Cathode Material In Solid Oxide Fuel Cells

The MIEC La1.5Sr0.5Ni1-yFeyO4 (y=0.1-0.4) oxides have been studied as cathode materials with La0.88Sr0.12Ga0.82Mg0.18O3-δ (LSGM) electrolyte. Total conductivity, thermal expansion, oxygen nonstoichiometry, and chemical compatibility with LSGM and Ce0.8Sm0.2O1.9 (SDC) were determined. The following fuel cells were tested: La1.5Sr0.5Ni1-yFeyO4 (y=0.1, 0.2, 0.3, 0.4)/SDC/LSGM/Sr2N0.75Mg0.25MoO6 (SNMM) and La1.5Sr0.5Ni0.6Fe0.4O4/SDC/LSGM/SDC/NiO-SDC. For the former, the maximum power densities were 218, 274, 222, and 390 mW/cm2 at 850 °C in case of y equal to 0.1, 0.2, 0.3, and 0.4, respectively. The latter cell showed maximum power density of 341 mW/cm2 at 850°C

Oxygen-ion and proton conductivity in the Ba3InGa2O7.5 complex oxide with incomplete oxygen sublattice

The Ba3InGa2O7.5 complex oxide, possessing the perovskite-related structure with structural oxygen vacancies, was first synthesized by the solid state method. The phase was found to be characterized by monoclinic symmetry (sp. gr. P2/c) with the following unit cell parameters: a = 7.942(1) Å, b = 5.868(5) Å, c = 18.201(6) Å, b = 91.52(9). Comprehensive investigations of electrical properties were carried out; ceramic material based on the complex oxide was shown to be a predominantly ionic conductor in the temperature range 450–900 oC. The conductivity is due to oxygen-ion transfer in dry conditions and oxygen-ion and proton transfer in wet atmosphere. The proton conductivity value is 4.5·10–5 S/cm, and the proton transport number is ~50% at 700 oC in wet air; at lower temperatures, proton transport becomes dominant. Prolonged treatment of the sample in water vapors below 450 oC leads to hydrolysis decomposition

Bulk Oxygen Diffusion and Surface Exchange Limitations in La2−xSrxNi1-yFeyO4+δ

The oxygen permeation flux through dense La1.2Sr0.8Ni0.9Fe0.1O4

Osteointegration Characterization of Additive Manufactured Porous Titanium Scaffold Based on Microhardness and Ca/P Ratio

Additive technologies are getting widely used in orthopedics due to the opportunity of full modelling of complex cellular structures and producing personalized implants. Titanium and its alloys are still the main material used for metallic implants manufacturing. In this study microhardness and Ca/P ratio of bone tissue surrounding the implant were investigated. By means of ABAQUS software titanium porous structure implants were designed. Their biomechanical properties were close to biomechanical properties of trabecular bone tissue. Direct metal laser sintering (DMLS) was used to manufacture implants from Ti-6Al-4V titanium alloy. They were augmented in trabecular bone defects of Chinchilla rabbits for 6, 12 and 25 weeks. The samples were examined by scanning electron microscopy (SEM) in a FEG SEM ZEISS CrossBeam AURIGA and the Ca/P ratio was calculated using the accompanying Oxford Inca software. Vickers hardness test method was performed for microhardness. It was shown that there was a significant increase in both mineral and mechanical properties of bone samples with an increase of observation period. The results found in this study illustrate a distinct relationship between the mineralization parameter of bone tissue and its microhardness (r = 0.808, r2 = 0.65).     Keywords: Scaffold, Microhardness, Titanium, Ca/P ratio, Bone defect, Osteointegration, Additive manufacturin

Synthesis, Crystal Structure, and Properties of NdNi0.5Mn0.5O3−

The crystal structure and properties of NdNi0.5Mn0.5O3

Crystal structure, oxygen non-stoichiometry and conductivity of Nd1-xAxMn0.5Fe0.5O3-δ (A=Ca, Sr, Ba)

This work was financially supported by RFBR (project No. 16-53-45010 IND_а)