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Current Topics in Biophysics

The Journal of Adam Mickiewicz University

Open access

International Agrophysics

The Journal of Institute of Agrophysics of Polish Academy of Sciences

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Open access

Germán Ayala, Rubén A. Vargas and Ana C. Agudelo

Abstract

Effects of temperature and glycerol concentration on rheological properties of potato starch solutions were investigated. The flow behaviour (shear stress against shear rate) was fitted to various models: power law, Herschel-Bulkley, Bingham, modified Bingham and Casson models. However, it was found that the Herschel-Bulkley model describes better the flow behaviour observed at various temperatures and glycerol concentrations, for flow behaviour index values between 0.44 and 0.78, typical of pseudoplastic solutions. The effect of glycerol concentration on each of the fitting parameters for Herschel-Bulkley model was well modelled by a second-degree polynomial at various temperatures. The simultaneous influence of glycerol concentration and temperature on shear stress could be represented empirically by a second-degree polynomial function that includes linear coupling between concentration and temperature. Finally, the variation of the consistency coefficient with both temperature and glycerol concentration was well described by an exponential expression, with an activation energy value of 2.78 kJ mol-1. The results indicate that both glycerol content and temperature have the effect of diluting potato starch solutions.

Open access

Leidy M. Chacua, Germán Ayala, Hernán Rojas and Ana C. Agudelo

Abstract

The rheological behaviour of vinasses derived from sugar cane was studied as a function of time (0 and 600 s), soluble solids content (44 and 60 °Brix), temperature (10 and 50°C), and shear rate (0.33 and 1.0 s−1). The results indicated that vinasses were time-independent at 25°C, where shear stress values ranged between 0.01 and 0.08 Pa. Flow curves showed a shear-thinning rheological behaviour in vinasses with a flow behaviour index between 0.69 and 0.89, for temperature between 10 and 20°C. With increasing temperature, the flow behaviour index was modified, reaching values close to 1.0. The Arrhenius model described well the thermal activation of shear stress and the consistency coefficient as a function of temperature. Activation energy from the Arrhenius model ranged between 31 and 45 kJ mol−1. Finally, the consistency coefficient as a function of the soluble solids content and temperature was well fitted using an exponential model (R2 = 0.951), showing that the soluble solids content and temperature have an opposite effect on consistency coefficient values.

Open access

Steffen Beck-Broichsitter, Heiner Fleige and Rainer Horn

.C., Searle P.L., and Daly B.K., 1987. Methods for chemical analysis of soils. New Zealand Soil Bureau Science Report 80. Beck-Broichsitter S., Fleige H., and Horn R., 2016. Schrump-frissgefährdung einer temporären mineralischen Oberflächenabdeckung. Deponietechnik, Januar 27-28, Hamburg, Germany. Beck Broichsitter S., Fleige H., and Horn R., 2017. Waste capping systems processes and consequences for the longterm impermeability. In: Soils within Cities (Eds M. Levin, H.J. Kim, J.L. Morel, W. Burghardt, P. Charzynski, R.K. Shaw). Catena Soil Sciences

Open access

Małgorzata Murat, Iwona Malinowska, Holger Hoffmann and Piotr Baranowski

Abstract

Meteorological time series are used in modelling agrophysical processes of the soil-plant-atmosphere system which determine plant growth and yield. Additionally, long-term meteorological series are used in climate change scenarios. Such studies often require forecasting or projection of meteorological variables, eg the projection of occurrence of the extreme events. The aim of the article was to determine the most suitable exponential smoothing models to generate forecast using data on air temperature, wind speed, and precipitation time series in Jokioinen (Finland), Dikopshof (Germany), Lleida (Spain), and Lublin (Poland). These series exhibit regular additive seasonality or non-seasonality without any trend, which is confirmed by their autocorrelation functions and partial autocorrelation functions. The most suitable models were indicated by the smallest mean absolute error and the smallest root mean squared error.

Open access

Pradyuman Barnwal, Ashish M. Mohite, Krishna K. Singh and Pankaj Kumar

Abstract

In this communication, selected physicomechanical characteristics of ground turmeric (cv. Prabha) were investigated for cryogenic and ambient grinding conditions of turmeric at different moisture contents (4, 6, 8 and 10% w.b.). A cryogenic grinder (Model: 100 UPZ, Hosokawa Alpine, Germany) and a micro pulverizer (hammer mill) were used for cryogenic and ambient grinding, respectively. The ground turmeric was graded in three grades viz. Gr-I, Gr-II and Gr-III with a sieve shaker using BSS Nos. 40, 85 and pan, respectively. Tap densities for cryogenic and ambient ground turmeric decreased from 678.7 (Gr-I) to 546.7 kgm-3 (Gr-III) and from 642.3 (Gr-I) to 468.6 kgm-3 (Gr-III), respectively, with the moisture increase. The angle of repose for cryogenic and ambient ground turmeric increased linearly from 26.85 (Gr-I) to 34.0° (Gr-III) and from 23.10 (Gr-I) to 28.06° (Gr-III), respectively with the increase in moisture content. The static coefficient of friction was the highest on plywood surface followed by mild steel sheet and galvanized iron sheet. The cryoground samples were found better in colour. Thermal conductivity of cryo-ground samples was higher than that of ambient ground samples. These physico-mechanical characteristics of cryogenic and ambient ground turmeric will be helpful for packaging, handling, and storage.

Open access

K. Miegel, K. Bohne and G. Wessolek

References Allen R.G., Wright M.E., and Burman R.D., 1989. Operational estimates of evapotranspiration. Agron. J., 81, 650-662. Bohne K., 2005. An Introduction into Applied Soil Hydrology. Catena Verlag Reiskirchen, Germany. Bonta J. and Müller M., 1999. Evaluation of the Glugla method for estimating evapotranspiration and groundwater recharge. Hydrol. Sci., 44(5), 743-761. Glugla G., Jankiewicz P., Rachinow C., Lojek K., and Richter K., 2003. BAGLUVA- Wasserhaushaltsverfahren zur

Open access

Justyna Lalak, Agnieszka Kasprzycka, Ewelina M. Paprota, Jerzy Tys and Aleksandra Murat

pre-treatment in biogas yield. Waste Manage, 30, 1780-1789. Cybulska J., Zdunek A., Sitkiewicz I., Galus S., Janiszewska E., Łaba S., and Nowacka M., 2013. Opportunities of use the pomace and other waste products from fruit and vegetable industry (in Polish). Fermentation, Fruits Vegetable Industry, 9, 22-24. DIN 38414-8, 1985. German standard methods for the examination of water, wastewater and sludge. Sludge and sediments (group S); determination of amenability to anaerobic digestion (S4) (in German). Beuth Verlag, Berlin. Germany. Dohanyos M