The impact of the exterior painted thin-layer render’s water vapour and liquid water permeability on the moisture state of the wall insulating system

The paper aims at the determination of the possible limits of vapour resistance and liquid water permeability alteration in the case of the exterior painted thin-layer render finish of the building walls from outside insulated with the mineral wool slabs when exploited in the area of cold and humid climate that could guarantee a normal moisture state of the wall insulating system. The moisture testing of the insulating system’s fragments was carried out in the climatic chamber, where the climatic parameters were modelled on the basis of the climatic typical of Lithuania. Thin-layer render was coated with acrylic paints. When the thickness of the paint coating on thin-layer render was increased from 0.08 mm to 0.24 mm, the liquid water absorption coefficient decreased by 59% and vapour resistance increased by 43%. It has also been determined that in the double-layer system paint coating – thin-layer render condensation moisture will be accumulated when the thickness of the air layer s_d equivalent to the material’s water vapour permeability is higher than 0.6 m. Rain will have an impact on the wall’s moisture state, when the liquid water absorption coefficient w of the double-layer system paint coating – thin-layer render is higher than 0.025 kg/(m² h^0.5). The micro-lens discovered in the areas of moisture accumulation by the thermographic analysis should be considered as the rudiments of the defect formation in the exterior insulating system.     

Transformation of Vegetable Oils into Hydrocarbons over Mesoporous-Alumina-Supported CoMo Catalysts

Deoxygenation of triglycerides over organized-mesoporous-alumina-supported CoMo catalysts (CoMo/OMA) has been investigated in this work. CoMo/OMA catalysts exhibited higher activity for deoxygenation of triglycerides than CoMo supported on MCM-41 (silica) and ordinary alumina supports. Two main deoxygenation pathways were found: hydrodeoxygenation and hydrodecarboxylation. Their extent was affected by reaction temperature, pressure and the support used. Hydrodeoxygenation was the main reaction under the studied conditions. The extent of hydrodecarboxylation increased with increasing reaction temperature and decreasing reaction pressure.     

High-alumina porcelain with the addition of a Li2O-bearing fluxing agent

We have studied the influence of increasing the amount of β-spodumene (LiAlSi₂O₆), as a Li₂O-containing flux, on the phase composition, the microstructure evolution and the physical properties of high-alumina porcelain. Quartz reacts with β-spodumene in the temperature range 1150–1250 °C, forming lithium aluminium silicates with a larger amount of SiO₂. The presence of lithium minerals contributes to a lower CTE for the fired bodies. At 1300 °C an improved flexural strength is achieved with compositions containing 1.0 or 1.2 wt.% of Li₂O, as a result of a more uniform microstructure. With increasing amounts of Li₂O the overfiring effect is greatly enhanced. The most favourable characteristics from an industrial perspective with regard to flexural strength and deformation during firing were attained by using a high-alumina porcelain composition containing 1.0 wt.% Li₂O.     

Numerical modeling of TeraHertz electronic devices

We investigate by means of Monte Carlo simulations the physical processes associated with the emission of TeraHertz radiation in different electronic devices. We analyze four alternative and complementary strategies which seem to be promising candidates to obtain the TeraHertz emission: (1) a nitride maser based on the optical-phonon transit-time resonance, (2) the high–order harmonic generation in bulk materials and nanometric Schottky-barrier diodes, (3) the excitation of coherent plasma oscillations in micron and submicron diodes, (4) the current instabilities and plasma oscillations in high electron mobility transistors (HEMT). The numerical results show that several physical mechanisms can be exploited to increase significantly the operating frequency of these devices and the best conditions to optimize the radiation emission in the TeraHertz range are studied in detail.     

A method for reduction of examples in relational learning

Feature selection methods often improve the performance of attribute-value learning. We explore whether also in relational learning, examples in the form of clauses can be reduced in size to speed up learning without affecting the learned hypothesis. To this end, we introduce the notion of safe reduction: a safely reduced example cannot be distinguished from the original example under the given hypothesis language bias. Next, we consider the particular, rather permissive bias of bounded treewidth clauses. We show that under this hypothesis bias, examples of arbitrary treewidth can be reduced efficiently. We evaluate our approach on four data sets with the popular system Aleph and the state-of-the-art relational learner nFOIL. On all four data sets we make learning faster in the case of nFOIL, achieving an order-of-magnitude speed up on one of the data sets, and more accurate in the case of Aleph.     

Transformation of chalcopyrite in the roasting process of copper concentrate in fluidized bed reactor

This work presents the results of investigation process of copper concentrate roasting in fluidized bed reactor with the aim of studying the transformations of copper concentrate minerals as well as to check the accordance with theoretical predictions. The roasted samples were examined using chemical analysis, x-ray diffraction, and mineral microscopy.     

Dependence of efficiency of pressure compaction on the cement type used

The results of the study on the properties of the pastes, with w/c ratio 0.20–0.10, compacted in the fresh state by the pressures between 27 and 82 MPa are given. The comparison of their properties with those found at the reference non-pressured cement pastes prepared with w/c ratio 0.30 showed the significantly increased compressive strength. Two effects were the cause: the significant decrease of the initial porosity due to the extremely low w/c ratios and the mechanical compaction of the fresh pastes. It has been found a significant increase of the effectiveness of the pressuring by the cement quality decrease. The long-term development of the properties of the pressured cement pastes is similar to the non-pressured cement pastes. At the conservation of the properties differences in the benefit of the pressured materials.     

Green tea preparation and its influence on the content of bioactive compounds

The effect of different extraction conditions and storage time of prepared infusions on the content of bioactive compounds of green teas and their antioxidant capacity were investigated. The content of total phenols, total flavonoids and total non-flavonoids in green teas was determined spectrophotometrically, while 7 flavan-3-ols, 6 phenolic acids and 3 methylxanthines were identified and quantified by using high performance liquid chromatography (HPLC–PDA). Among the tested green teas bagged green tea Twinings of London was recognized as the richest source of phenolic compounds (3585 mg/L GAE of total phenols). The most abundant phenolic constituents of green tea were flavan-3-ols, of which EGCG was prevailing in all teas (94.54–357.07 mg/L). The highest content of caffeine, as the most abundant methylxanthine, was determined in powdered green tea. The findings of this investigation suggest that extraction efficiency of studied bioactive compounds from green tea depends on the extraction conditions and that maximum extraction efficiency is achieved during aqueous extraction at 80 °C, for 5′ (powder), 15′ (bagged) and 30′ (loose leaf). In order to determine the antioxidant capacity of teas the DPPH, ABTS and FRAP assays were applied. Regardless of the extraction conditions all green teas exhibited significant antioxidant capacity in vitro, which was in correlation with their phenolic content, confirming that green tea is one of the best dietary sources of antioxidants.     

Comparative Gas Chromatographic–Mass Spectrometric Evaluation of Hop (Humulus lupulus L.) Essential Oils and Extracts Obtained Using Different Sample Preparation Methods

The main aim of investigations was to identify chemotypes and determine differences between some domestic hop varieties and wild hops, which were collected from some regions of Lithuania and cultivated at the same edafoclimatic conditions in hops collection of Kaunas Botanical Garden of Vytautas Magnus University. One of objectives was to compare essential oils of hops (2 years harvest) by the evaluation of volatiles content. Among the main components of hop essential oils monoterpenes (β-myrcene) and sesquiterpenes (α-humulene and β-caryophyllene) were determined using gas chromatography coupled with mass spectrometry (GC-MS). Retention parameters (t _R, calculated retention index, and Kovats retention index) and m/z value of molecular ion for selected compounds from hop essential oils were determined. Samples were prepared by applying solid phase microextraction (SPME), supercritical fluid extraction (SFE) and accelerated solvent extraction (ASE). The steam distillation was used to obtain hop essential oils. The chemometric comparison of domestic and wild hops based on GC-MS analysis data was carried out. The obtained statistical results allow us to classify the investigated wild forms and domestic varieties of hops according to the similarities of their chemotypes. The concentration of β-myrcene, α-humulene in hop essential oils obtained from cones 2 years harvests is much higher than other volatile organic compounds (15.2–23.7 % in total contribution). In analysed essential oils β-farnesene is a constituent in higher quantity of hop essential oils obtained from cones from second time harvest than from cones from first harvest. This can be explained by the year-to-year vegetation conditions difference.