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Pine pollen grains in coastal waters of the Baltic Sea

100%

Pawlik M. , Ficek D.

2016

tom Vol. 45, No. 1

35--41

Measurements relating to a yellow deposit covering large areas of the Baltic Sea in spring are reported. Analysis of water samples showed it to be of terrestrial origin and to consist mainly of pine pollen grains. The equivalent spherical diameter (ESD) of these grains ranged from 29.1 to 78.4 μm, with a maximum between 47.7 and 56.3 μm. Surface water concentrations of pollen in the coastal zone near Ustka showed that its proportion in the total suspended particulate matter (SPM) might be as high as 30-40%. Such high surface water concentrations of hitherto neglected substances critical to water color formation can give rise to serious errors in remote measurements of water composition and properties.

Predictive analysis on the influence of AL2o3 and CuO nanoparticles on the thermal conductivity of R1234yf-based refrigerants

84%

Bibin B. S. , Bhramara P. , Mystkowski A. , Gundabattini E.

tom Vol. 18, no. 3

474--482

Nano-enhanced refrigerants are substances in which the nanoparticles are suspended in the refrigerantatthe desired concentration. They have the potential to improve the performance of refrigeration and air-conditioning systems that use vapour compression. This study focuses on the thermal conductivity of alumina (Al2O3) and cupric oxide (CuO) nanoparticles immersed in 2,3,3,3-tetrafluoropropene (R1234yf). The thermal conductivity of nano-refrigerants was investigated using appropriate models from earlier studies where the volume concentration of particles and temperatures were varied from 1% to 5% and from 273 K to 323K, respectively. The acquired results are supported by prior experimental investigations on R134a-based nano-refrigerants undertaken by the researchers. The main investigation results indicate that the thermal conductivity of Al2O3/R1234yf and CuO/R1234yf is enhanced with the particle concentrations, interfacial layer thickness, and temperature. Also, the thermal conductivity of Al2O3/R1234yf and CuO/R1234yf decreases with particle size. The thermal conductivity of Al2O3/R1234yf and CuO/R1234yf nano-refrigerants become enhanced with a volume concentration of nano-sized particles by 41.2% and 148.1% respectively at 5% volume concentration and 323K temperature. The thermal conductivity of Al2O3/R1234yf reduces with temperature, by upto 3% of nanoparticle addition and after that, it enhances. Meanwhile, it declines with temperature, by upto 1% of CuO nanoparticle inclusion for CuO/R1234yf. CuO/R1234yf has a thermal conductivity of 16.69% greater than Al2O3/R1234yf at a 5% volume concentration. This paper also concludes that, among the models for thermal conductivity study, Stiprasert’s model is the most accurate and advanced.