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15 záznamů v Medvik Filtry

Článek

Polymer scaffolds with no skin-effect for tissue engineering applications fabricated by thermally induced phase separation

Biomedical materials. 2016 ; 11 (1) : 015002. [pub] 20160111

Biomed Mater
ISSN 1748-605X
Medvik
Zdroj

Thermally induced phase separation (TIPS) based methods are widely used for the fabrication of porous scaffolds for tissue engineering and related applications. However, formation of a less-/non-porous layer at the scaffold's outer surface at the air-liquid interface, often known as the skin-effect, restricts the cell infiltration inside the scaffold and therefore limits its efficacy. To this end, we demonstrate a TIPS-based process involving the exposure of the just quenched poly(lactide-co-caprolactone):dioxane phases to the pure dioxane for a short time while still being under the quenching strength, herein after termed as the second quenching (2Q). Scanning electron microscopy, mercury intrusion porosimetry and contact angle analysis revealed a direct correlation between the time of 2Q and the gradual disappearance of the skin, followed by the widening of the outer pores and the formation of the fibrous filaments over the surface, with no effect on the internal pore architecture and the overall porosity of scaffolds. The experiments at various quenching temperatures and polymer concentrations revealed the versatility of 2Q in removing the skin. In addition, the in vitro cell culture studies with the human primary fibroblasts showed that the scaffolds prepared by the TIPS based 2Q process, with the optimal exposure time, resulted in a higher cell seeding and viability in contrast to the scaffolds prepared by the regular TIPS. Thus, TIPS including the 2Q step is a facile, versatile and innovative approach to fabricate the polymer scaffolds with a skin-free and fully open porous surface morphology for achieving a better cell response in tissue engineering and related applications.

Článek

Sucho trápí přírodu i naše zdraví. Šíří se laryngitida a záněty

Causa subita. 2015 ; 18 (5) : 203.

Causa subita (Praha)
ISSN 1212-0197
Medvik
Zdroj

Topná sezóna obvykle startuje ve chvíli, kdy venkovní teplota dlouhodobě klesne pod 13* C. Topení s sebou ovšem přináší další vysušování vzduchu v interiérech a s ním se pojí řada zdravotních problémů. Škrábání v krku, ucpaný nos, pálení očí či chronická onemocnění horních i dolních cest dýchacích. To jsou nejčastější problémy způsobené vzduchem, jehož vlhkost klesá pod 40%. Pomoct přitom může i obyčejné prostěradlo.

Článek

The changing character of household waste in the Czech Republic between 1999 and 2009 as a function of home heating methods

Waste management. 2013 ; 33 (9) : 1950-7.

Waste Manag
ISSN 1879-2456
Medvik
Zdroj

The authors of this paper report on the changing character of household waste, in the Czech Republic between 1999 and 2009 in households differentiated by their heating methods. The data presented are the result of two projects, financed by the Czech Ministry of Environment, which were undertaken during this time period with the aim of focusing on the waste characterisation and complete analysis of the physicochemical properties of the household waste. In the Czech Republic, the composition of household waste varies significantly between different types of households based on the methods of home heating employed. For the purposes of these studies, the types of homes were divided into three categories - urban, mixed and rural. Some of the biggest differences were found in the quantities of certain subsample categories, especially fine residue (matter smaller than 20 mm), between urban households with central heating and rural households that primarily employ solid fuel such coal or wood. The use of these solid fuels increases the fraction of the finer categories because of the higher presence of ash. Heating values of the residual household waste from the three categories varied very significantly, ranging from 6.8 MJ/kg to 14.2 MJ/kg in 1999 and from 6.8 MJ/kg to 10.5 MJ/kg in 2009 depending on the type of household and season. The same factors affect moisture of residual household waste which varied from 23.2% to 33.3%. The chemical parameters also varied significantly, especially in the quantities of Tl, As, Cr, Zn, Fe and Mn, which were higher in rural households. Because knowledge about the properties of household waste, as well as its physicochemical characteristics, is very important not only for future waste management, but also for the prediction of the behaviour and influence of the waste on the environment as the country continues to streamline its legislation to the European Union's solid waste mandates, the results of these studies were employed by the Czech Ministry of Environment to optimise the national waste management strategy.