Bucharest, Romania
Bucharest, Romania

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Jipa S.,University Valahia of Targoviste | Gorghiu L.M.,University Valahia of Targoviste | Dumitrescu C.,University Valahia of Targoviste | Zaharescu T.,INCDIEICPE CA | Mantsch A.,INCDIEICPE CA
Revista de Chimie | Year: 2011

The thermoluminescence (TL) technique was utilized to study sand samples from Romania (Valea Cernei) batches for radiation dosimetry. The sand samples have been studied in relation to the main dosimetric properties, such as: glow curve structure, linear dose response (3+104 Gy), low thermal fading. These features provide a useful means of using the present sand samples as gamma dosimeter.

Emandi A.,University of Bucharest | Vasiliu C.I.,Romanian National Institute for Optoelectronics | Budrugeac P.,INCDIEICPE CA | Stamatin I.,University of Bucharest
Cellulose Chemistry and Technology | Year: 2011

A non-invasive integrated method for assessing cellulose and hemicelluloses/lignin ratio in different wooden pieces was developed by coupling infrared spectroscopy (FTIR-ATR) with thermo-gravimetric analysis (TGA). The method could be helpful for a precise assessment of the cellulose and hemicelluloses/lignin ratio necessary for the characterization of wooden artefacts. Thirteen wood species of hardwood lime (Tilia cordata), oak (Quercus robur), beech (Fagus sylvatica L.), poplar (Populus), maple (Acer palmatum), cherry tree (Prunus avium), horn beam (Carpinus betulus), walnut (Juglans regia L.), balsa, sycamore maple (Acer pseudo platanus), African pole (Pyrus communis), and two wood species of softwood fir (Abies), pine (Pinus silvestris) were investigated in fresh and dried state. The ratio between the normalized peak area A 1370(corresponding to the mass loss of cellulose and hemicelluloses) and A 1505(corresponding to the mass loss of lignin) was determined - from the FTIR spectra - as A 1370/A 1505 = R FTIR. From TGA data, the ratio between the mass loss of cellulose and hemicelluloses (Δm Hc) and the mass loss of lignin was calculated: Am L as Δm Hc/Δm L = R TG . A good correlation was obtained, with a small variation between the difference in the two parameters, AR = R FTIR - R TG, related to the nature of wood (+0.015 in fresh softwood and +0.065 in fresh hardwood), (+0.265 in dried softwood and +0.18 in dried hardwood). The results obtained show that TGA (a quantitative and invasive method) may be successfully used as a complementary tool of FT-IR analysis (a qualitative and non-invasive method) for the rapid assessments required by the restoration processes as to the degradation stage of wooden artefacts.

Mandrea L.,Polytechnic University of Bucharest | Babutanu C.A.,Polytechnic University of Bucharest | Baran G.,Polytechnic University of Bucharest | Oprina G.,INCDIEICPE CA | Bunea R.,INCDIEICPE CA
Revista de Chimie | Year: 2010

The efficiency of a suspension homogenizationlmixing reactor is evaluated by a uniform concentration of the suspension and low specific energy consumption (kW/m3). For a reactor with given geometry and volume, free or intubated impellers are used for the mixing of the suspension. In this work is studied the influence of the draft tube length. The streamlines corresponding to the flow of water are obtained through the numerical integration of Navier-Stokes equations. The increasing of the draft tube length modifles the flow, leading to the reduction of the number and intensity of the vortices inside the reactor (outside the draft tube). These vortices can lead to suspensions agglomeration, facilitating the sedimentation and thus increasing the energy consumption of the homogenization process.

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