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Bratislava, Slovakia

Surina I.,Slovak University of Technology in Bratislava | Jablonsky M.,Slovak University of Technology in Bratislava | Haz A.,Slovak University of Technology in Bratislava | Sladkova A.,Slovak University of Technology in Bratislava | And 3 more authors.
BioResources | Year: 2015

Lignin is an attractive, renewable raw material provided by all types of agricultural and silvicultural vegetation. The precipitation of lignin fractions through acidification of the black liquor was performed and the products characterized for the following parameters: C, H, N, and S elemental composition; zeta potential; electrophoretic mobility; heating value; molecular weight; content of non-conjugated, conjugated, and total phenolic hydroxyl groups; and total yield of oxidation products. Lignin was isolated from black liquor by adding sulphuric acid at four levels of concentration (5, 25, 50, and 72 wt%) and subsequently adjusting the pH to 5. A comparison study of the physico-chemical and surface properties was also performed. The acid concentration influenced the yield of precipitated lignin and had an effect on the properties of precipitated lignin and the content of non-conjugated, conjugated, and total amount of phenolic hydroxyl groups. However, the concentration of acid had no relevant effect on the heating value, molecular weight, polydispersity, total yield of oxidation products, or the elemental composition of isolated lignin. Source

We prove that every orthocomplete homogeneous effect algebra is sharply dominating. Let us denote the greatest sharp element below x by x↓. For every element x of an orthocomplete homogeneous effect algebra and for every block B with x ∈ B, the interval [x↓, x] is a subset of B. For every meager element (thatmeans, an element x with x↓ = 0), the interval [0, x] is a complete MV-effect algebra. As a consequence, the set of all meager elements of an orthocomplete homogeneous effect algebra forms a commutative BCK-algebra with the relative cancellation property. We prove that a complete lattice ordered effect algebra E is completely determined by the complete orthomodular lattice S(E) of sharp elements, the BCKalgebra M(E) of meager elements and a mapping h: S(E) → 2M(E) given by h(a) = [0, a] ∩ M(E). © Springer Science + Business Media B.V. 2009. Source

Prokopcak L.,Radlinskeho
Advanced Materials Research | Year: 2014

The objective of any construction work is defined as the optimal use of resources, it is focused on building efficiency, so as to ensure quality in reaching the minimum construction costs and ensure environmental protection, safety at work. The building production is affected by many factors. With some we can count, but we cannot predict some for certain in advance. The essential precondition for successful implementation of a construction is thorough and timely preparation of pre-production and production engineering (technology designing), which provides for the effective implementation of the works. © (2014) Trans Tech Publications, Switzerland. Source

Prokopcakova K.,Radlinskeho
Advanced Materials Research | Year: 2014

Environment is becoming a significant development potential of a country and the effort dwells in minimizing the negative impacts affecting its quality. Researches show that in the branches of industry in the EU construction is the third largest polluter of the environment. Requirements of securing the environmental protection are more demanding when it comes to qualitative properties of construction materials, building machines, technological building processes, etc. Due to this it is necessary to derive from the confrontation of the current status with requirements of securing maximum effectiveness of the building production process at minimizing negative impacts on the environment. © (2014) Trans Tech Publications, Switzerland. Source

Cavajda V.,Comenius University | Uhlik P.,Comenius University | Derkowski A.,Polish Academy of Sciences | Caplovicova M.,Comenius University | And 4 more authors.
Clays and Clay Minerals | Year: 2015

Talc is an important industrial mineral with a broad range of applications. Particle size and crystal structure have a significant influence on the potential uses. The present study examined the influence of grinding and ultrasound treatment on talc from a new deposit, Gemerská Poloma, in Slovakia. The general knowledge that grinding produces progressive structural disorder leading to amorphization, whereas sonication has a negligible effect on the talc crystal structure, was confirmed by X-ray diffraction (XRD), infrared (IR) spectroscopy, and transmission electron microscopy (TEM). Partial reduction of particle size along with delamination was observed by XRD after sonication, low-angle laser light scattering (LALLS), scanning electron microscopy (SEM), and TEM. The specific surface area (SSA) increased slightly after prolonged sonication, but grinding initially caused a rapid increase in SSA followed by a drastic decrease after prolonged grinding time of up to 120 min which was attributed to the aggregation of amorphized talc. Sonication and grinding had different influences on the thermal behavior of the talc studied. Sonication decreased slightly the dehydroxylation temperature, whereas grinding added a significant mass loss at low temperature, arising from the dehydration of hydrated Mg cations released from the talc structure during amorphization. The initial high whiteness value of talc decreased slightly after grinding or sonication. Thermogravimetry was suggested as a useful tool to track and predict changes in the talc structure upon sonication and grinding. © 2015, Clay Minerals Society. All rights reserved. Source

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