381 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
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Tailoring chitosan/collagen scaffolds for tissue engineering: Effect of composition and different crosslinking agents on scaffold properties.
Chitosan/collagen (Chit/Col) blends have demonstrated great potential for use in tissue engineering (TE) applications. However, there exists a lack of detailed study on the influence of important design parameters (i.e, component ratio or crosslinking methods) on the essential properties of the scaffolds (morphology, mechanical stiffness, swelling, degradation and cytotoxicity). This work entailed a systematic study of these essential properties of three Chit/Col compositions, covering a wide range of component ratios and using different crosslinking methods. Our results showed the possibility of tailoring these properties by changing component ratios, since different interactions occurred between Chit/Col: samples with Chit-enriched compositions showed a hydrogen-bonding type complex (HC), whereas a self-crosslinking phenomenon was induced in Col-enriched scaffolds. Additionally, material and biological properties of the resultant matrices were further adjusted and tuned by changing crosslinking conditions. In such way, we obtained a wide range of scaffolds whose properties were tailored to meet specific needs of TE applications.The authors are grateful to Dr. von Kobbe (Chimera Pharma of Bionostra Group) for the gift of MCF7 cells. The financial support of the Ministerio de Ciencia e Innovación of Spain (FIS PS09/01513), and the FPI grant from UCM to A. Martínez are gratefully acknowledged.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.carbpol.2015.06.08
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
Photoelectric and Spectral Properties of Composite Films based on GCBE-Oligomer with Different Concentrations of Polymethine Dyes
Thin film of composites based on N-epoxypropylcarbazole and n-butylglycidyl ether co-oligomer (GCBE) sensitized by various concentrations of cationic polymethine dyes with different polymethine chain length have been prepared. Their photophysical, electrical, and spectral properties have been investigated. All studied composite films have been shown to exhibited photoconductivity effect. In film composites with high concentration of the dye photovoltaic effect have been detected. The diffusion nature of this effect and its features correlation with electronic properties of PCFs components has been established
Holographic Recording Media based on Electron Donor Oligomers
For optical holographic recording by photothermoplastic technique reversible holographic media based on oligomers with hole type of conductivity are used. New carbazole containing radial tetrasubstituted silanes and germanes are described in the present work
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
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