455 research outputs found
Principles and Criteria of Phytocenotic Diversity Conservation (Through the Example of European Countries and Russia)
The article presents the review of currently existing views on the problem of phytocoenotic diversity protection in European countries and Russia. The principles and criteria for the identification of rare plant communities in need of protection, used by scientists from different countries are described. The authors had defined already published works of a monographic nature and projects, containing the information on the phytocenotic diversity of Europe in need of protection, and Green Books, published in the Russian Federation. Special attention is paid to the determination process of plant communities. It is noted that nowadays there is no single concept for the creation of Green Books. The phytocenosis protection inventories created in European countries that have a legislative basis, the Russian Green Books include vegetation monitoring data and have no legal basis
Estudio in vitro de la actividad citotóxica de resinas dentales tipo BIS-GMA
Las resinas composites se emplean desde hace varias décadas en distintas aplicaciones
estomatológicas, volviéndose indispensables para lograr una alta calidad en los servicios modernos.
Uno de los monómeros acrílicos más utilizados en estos materiales poliméricos de recubrimiento
es el 2-bis-[p-(2-hidroxi-3-metacriloxipropoxi) fenil] propano, conocido comúnmente como Bis-
GMA. El conocimiento de las interacciones de estos materiales con el sistema biológico es de vital
importancia debido al uso tan difundido de los mismos en la práctica clínica. El comportamiento de
una célula viva en contacto con un material extraño es un problema esencial en las aplicaciones
biomédicas de polímeros sintéticos. Los ensayos in vitro son sistemas muy útiles para la evaluación
de los efectos biológicos de los biomateriales.
En el laboratorio de Inmunofarmacología del INOR se llevó a cabo la evaluación de la
toxicidad de dos resinas dentales tipo Bis-GMA producidas por el Centro de Biomateriales de la
Universidad de La Habana: el Obtudent Fotocurado (FC), resina fotopolimerizable para restauraciones
dentales y el Cubridem Autocurado (AC), sellante dental para fosas y fisuras. Este estudio
forma parte de las evaluaciones preclínicas biológicas de biomateriales y equipos médicos
implantables que se lleva a cabo en Cuba a través de la Red Funcional de Implantología del
Ministerio de Salud Pública. Se aplicó el método de citotoxicidad in vitro descrito por Stanley para
la evaluación toxicológica de materiales dentales. Ambos composites resultaron citotóxicos para
la línea de fibroblastos L929, lo que se corresponde con lo descrito en la literatura para este tipo
de material. Su citotoxicidad se encontró en el rango de la de los análogos comerciales evaluados.Peer Reviewe
Space-borne Observations of Atmospheric Pre-Earthquake Signals in Seismically Active Areas: Case Study for Greece 2008-2009
We are conducting theoretical studies and practical validation of atm osphere/ionosphere phenomena preceding major earthquakes. Our approach is based on monitoring of two physical parameters from space: outgoi ng long-wavelength radiation (OLR) on the top of the atmosphere and e lectron and electron density variations in the ionosphere via GPS Tot al Electron Content (GPS/TEC). We retrospectively analyzed the temporal and spatial variations of OLR an GPS/TEC parameters characterizing the state of the atmosphere and ionosphere several days before four m ajor earthquakes (M>6) in Greece for 2008-2009: M6.9 of 02.12.08, M6. 2 02.20.08; M6.4 of 06.08.08 and M6.4 of 07.01.09.We found anomalous behavior before all of these events (over land and sea) over regions o f maximum stress. We expect that our analysis reveal the underlying p hysics of pre-earthquake signals associated with some of the largest earthquakes in Greece
Structural features of highly stable reproducible C₆₀ fullerene aqueous colloid solution probed by various techniques
The method of preparation of highly stable reproducible C₆₀ fullerene aqueous colloid solution is described. The structural organization of C₆₀ fullerenes in aqueous solution was studied and analyzed in detail using various techniques such as chemical analysis, UV/VIS spectroscopy, atomic force and scanning tunneling microscopy, dynamic light scattering, and zeta potential method
The Intrinsic Dimensionality of Attractiveness: A Study in Face Profiles
The study of human attractiveness with pattern analysis techniques is an emerging research field. One still largely unresolved problem is which are the facial features relevant to attractiveness, how they combine together, and the number of independent parameters required for describing and identifying harmonious faces. In this paper, we present a first study about this problem, applied to face profiles. First, according to several empirical results, we hypothesize the existence of two well separated manifolds of attractive and unattractive face profiles. Then, we analyze with manifold learning techniques their intrinsic dimensionality. Finally, we show that the profile data can be reduced, with various techniques, to the intrinsic dimensions, largely without loosing their ability to discriminate between attractive and unattractive face
Quasiperiodic Patterns in Boundary-Modulated Excitable Waves
We investigate the impact of the domain shape on wave propagation in
excitable media. Channelled domains with sinusoidal boundaries are considered.
Trains of fronts generated periodically at an extreme of the channel are found
to adopt a quasiperiodic spatial configuration stroboscopically frozen in time.
The phenomenon is studied in a model for the photo-sensitive
Belousov-Zabotinsky reaction, but we give a theoretical derivation of the
spatial return maps prescribing the height and position of the successive
fronts that is valid for arbitrary excitable reaction-diffusion systems.Comment: 4 pages (figures included
Destruction of humic substances by pulsed electrical discharge
Currently, the water recourses in the territory of Tomsk region are groundwater which is limited to the high concentration of iron and manganese ions and organic substances. These impurities present in water in different forms such as soluble salts ant the colloid forms. Therefore, the present work is a part of a continuations researcher of the processes in natural waters containing humic substances at the influence of pulsed electrical discharges in a layer of iron pellets. It is shown that the main stage of water purification process of humic substances during treatment by pulsed electric discharge in the layer of iron granules is a difficult process including several stages such as formation of iron oxyhydroxide colloid particles, sorption and coagulation with humic macromolecules substances, growth of particle dispersed phase and precipitation. The reason for the formation and coagulation of the dispersed phase is a different state of charge of the colloid particles (zeta potentials of (Fe (OH)3) is +8 mV, zeta potentials of (Humic substances) is -70 mV. The most intense permanganate oxidation reduction to the maximum permissible concentration occurs at the processing time equal to 10 seconds. The contact time of active erosion products with sodium humate is established and it equals to 1 hour. The value of permanganate oxidation achieves maximum permissible concentration during this time and iron concentration in solution achieves maximum permissible concentration after filtration
- …