http://195.117.226.27:8080/xmlui/handle/123456789/116 Tue, 14 Apr 2026 16:10:09 GMT 2026-04-14T16:10:09Z http://195.117.226.27:8080/xmlui/handle/123456789/525 Modelling effective thermal conductivity coeficient of Salix viminalis L. dried pieces Słomka-Polonis, Karolina; Łapczyńska-Kordon, Bogusława; Francik, Sławomir; Francik, Renata The effective thermal conductivity coefficient (λef) of willow Salix Viminalis L. dried pieces was studied by drying the willow at various temperatures. The willow was acquired from the energy crop plantation of the University of Agriculture in Krakow. The dried pieces of willow were covered with insulating coating and then heated in thermal chamber with constant drying agent (air) velocity under various conditions of drying air temperature: 313.15-343.15 K (40-70 °C). The experiment set up caused the longitudinal direction of the heat flow. Single piece of willow was heated in 15 minutes period. With the use of two thermocouples the temperature of single sample was measured in the two points: on the surface and at half-height in the middle. The specific density and porosity of the willow particles were measured with AccuPyc II 1340 and GeoPyc 1360 pycnometers. On basis of the Fourier equation of heat transfer and concept of reverse problem formulation the thermal conductivity coefficient (λ) was calculated. The effective thermal conductivity coefficient (λef) was determined using a general model, in which porosity and density of the willow pieces were covered. The effect of the drying agent temperature on the (λef) coefficient was investigated. The rise in the air temperature led to an increase in the (λef) coefficient rate in the experiments. At the 15th minute the (λef) coefficient varied from 0.038 (W⋅m-1⋅K-1) at 313.15 K (40 °C) temperature and 0.086 (W⋅m-1⋅K-1) at 343.15 K (70 °C). The performance of the model was evaluated by comparing the correlation coefficient (R2), root mean square error (RMSE), mean absolute percentage error (MAPE) and the chi-square (χ2) between the observed and the predicted effective thermal conductivity coefficient (λef) ratios. The calculated statistical parameters varied over the studied temperature range: RMSE was below 0.014, MAPE ranged from 6 to 17 %, R2 ranged from 0.91 to 0.97, χ2 below 0.019 showed good model adjustment to the experimental data. Mon, 01 Jan 2018 00:00:00 GMT http://195.117.226.27:8080/xmlui/handle/123456789/525 2018-01-01T00:00:00Z http://195.117.226.27:8080/xmlui/handle/123456789/524 Oil from seeds of various grape cultivars grown in Southern Poland and its antioxidant properties Francik, Renata; Krośniak, Mirosław; Gastol, Maciej; Kondratowicz-Pietruszka, Elżbieta In Poland seeds from grape are a waste product that is not used as a source of valuable substances for humans. The main aim of this study was to obtain and analyze the oil from the seeds of seven grape cultivars from the Garlicki Lamus vineyard located in Garlica Murowana (near Krakow, Poland, coordinates: 19º56’E, 50º08’N). Our work is presenting estimation of the percentage content of oil and fatty acid composition derived from cultivars of grape seed (Leon Millot, Jutrzenka, Bianca, Regent, Seyval Blanc, Marechal Foch, Sibera). In samples the following fatty acids have been determined: C18:2 from 76.69 % (Bianca) to 81.33 % (Marechal Foch), C18:1 from 10.67 % (Marechal Foch) to 14.15 % (Sibera), C16:0 – from 5.05 % (Seyval Blanc) to 7.40 % (Bianca), C18:0 (stearic acid) from 2.10 % (Sibera) to 3.16 % (Seyval Blanc). On the other hand, the lowest concentration was found for C18:3, the presence of which in measurable amounts was found in four of the seven analyzed vine varieties (Bianca, Regent, Seyval Blanc, Sibera). Also the percentage of the oil obtained from the seeds of the analyzed samples was measured. The maximal concentration of oil was obtained for Sibera (12.70 ± 0.88 %) cultivar and the smallest for Marechal Foch (6.48 ± 0.49 %). Seeds obtained from grape pomace can provide excellent raw material for the oil, which can be used in many branches of industry. Extracts from the oil were tested for the content of total polyphenols level from 34.7mg·l-1 (Marechal Foch) to 85.1 mg·l-1 (Seyval Blanc) and total antioxidant status, which was determined by the FRAP (Ferric Reducing Antioxidant Power) method from 19.72 μmolFe2+·l-1 (Marechal Foch) to 817.64 μmolFe2+·l-1 (Sibera). In addition, antioxidant capacity was measured, using the method of reduction of DPPH radical reduction. The lowest activity was measured for Regent (4.65 %) and the highest for Marechal Foch (11.62 %). There has also been strong antioxidant potential for two of the seven studied grape seed cultivars – Seyval Blanc and Sibera. Mon, 01 Jan 2018 00:00:00 GMT http://195.117.226.27:8080/xmlui/handle/123456789/524 2018-01-01T00:00:00Z