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Arthur Bradley,1 Renfeng Xu,1,2 Huachun Wang,2 Matt Jaskulski,1 Xin Hong,3 Nicolette Brink,3 Stephen Van Noy3 1School of Optometry, Indiana University, Bloomington, IN 47405, USA; 2Department of Ophthalmology and Vision Science, University of Nebraska Medical Center, Omaha, NE 68198, USA; 3Alcon Research Laboratories, Fort Worth, TX 76134-2001, USACorrespondence: Arthur BradleyIndiana University, 800 E Atwater Ave, Bloomington, IN 47405, USATel +1 812-855-2465Fax +1 812-855-7045Email bradley@indiana.eduPurpose: The human eye exhibits large amounts (2.5 diopters) of longitudinal chromatic aberration (LCA). Its impact on polychromatic image quality, however, has been shown experimentally and by computer modeling to be small or absent. We hypothesized that modest changes in pseudophakic LCA created by higher and lower Abbe number materials will have little or no impact on polychromatic image quality in pseudophakic eyes.Materials and Methods: Using published chromatic and monochromatic aberration data from pseudophakic eyes and higher and lower Abbe number materials (37 and 55), we computed monochromatic point spread functions for 21 wavelengths across the visible spectrum. After weighting by either the RGB spectra of a liquid crystal display or by a flat white spectrum, they were weighted by the human spectral sensitivity function (Vλ) before being added to generate polychromatic PSFs.Results: In the absence of monochromatic aberrations, the reduced LCA due to higher Abbe number intraocular lens (IOL) materials resulted in a reduction of 0.08 diopters in the mean defocus generated by LCA. At the retinal plane, the higher Abbe number pseudophakic model produced improvements in polychromatic modulation transfer functions (MTFs) similar to those generated by a 0.05 diopter reduction in spherical defocus. When monochromatic aberrations were added to make the model more representative of actual pseudophakic eyes, the differences in image quality became sub-threshold for human vision or disappeared completely.Conclusion: The anticipated gains in polychromatic image quality from employing higher Abbe number IOL materials with reduced LCA do not materialize in plausible aberrated models of pseudophakic eyes.Keywords: Abbe number, chromatic aberrations, IOL, image quality

The paper presents a research monitoring platform implemented for the Sulejow dam reservoir located in Central Poland; the goal was to assess the quality status of the reservoir’s waters during the vegetation season of 2015. Article presents the results of mobile field measurements together with laboratory analyses of biogenic parameters, in order to provide a broad picture of changes in water quality during the analysed period. Changes in water quality were evaluated based on the following parameters: chlorophyll a, ammonium ions, pH, water temperature, blue-green algae concentration, conductivity and dissolved oxygen. Analysis was complemented by laboratory measurements of the chemical parameters: nitrates, phosphates, 5-d biochemical oxygen demand, chemical oxygen demand and total organic carbon. Extensive mobile experiments enabled the mapping of the distribution of contaminants in the lake (ArcGIS). Chlorophyll a exceeded allowable values during the entire vegetation season; furthermore, the high water temperatures, high concentrations of dissolved oxygen and low concentrations of biogenic compounds illustrate the advanced eutrophication of the reservoir. Present conditions prevent any recreational use of the reservoir and generates not only environmental but also economic losses. [ABSTRACT FROM AUTHOR]

In this work, a novel methodology for the development of a high-accuracy computational fluid dynamics (CFD) model for the spray-drying process is described. Starting point is an own spatially resolving model of droplet/particle drying, which was developed and validated on the basis of a series of single droplet drying (SDD) experiments. This sophisticated model is transformed to a much simpler version: the characteristic drying curve approach, after running the full SDD model in a wide range of operating conditions. Then, the obtained reduced model is implemented into the CFD solver. The CFD spray-drying model takes into account the hydrodynamics of the continuous phase, particle drying kinetics, changes in the particle diameter, and the heat loss from the drying chamber to the environment. Validation of the entire procedure is provided by data obtained from drying experiments performed in a co-current laboratory spray tower. High accuracy of the developed CFD model of skim milk spray drying has been found for both phases, for the mean outlet temperature of the continuous phase (air) and for the change in average particle moisture content along the spray tower (discrete phase). [ABSTRACT FROM PUBLISHER]

Single-droplet drying experiments were conducted with solutions of dairy materials in water (skim milk and its constituents, namely lactose, whey protein, and a lactose–whey mixture) at both moderate and elevated temperatures, at which inflation/deflation phenomena are observed. The experimental data were used to obtain parameters of a spatially resolving single-droplet drying model, which was extended to empirically account for inflation/deflation. Inflation/deflation parameters and conditions for crust formation at the transition from the first to the second drying stage were clearly solute dependent, and respective correlations with drying conditions were developed for the investigated dairy materials. The parametrized model was shown to satisfactorily describe measured data in respect to drying curve, drying time, and the diameter of product particles. [ABSTRACT FROM PUBLISHER]

A 3D CFD model of the agglomeration of droplets and particles in a counter-current spray-drying process was developed and verified. An original discrete phase model was elaborated, with an agglomeration module taking into account hydrodynamic segregation of particles, droplet coalescence, and droplet shrinkage for accurate calculations of mass balance of the discrete phase. The characteristic drying curves were applied to the model of particle moisture evaporation, which included the coupling of particle agglomeration with heat, mass, and momentum transfer between the discrete and continuous phases. Two agglomeration zones were observed in the tower: wet particle agglomeration in the atomization zone, and “dry agglomeration” above the air inlets, due to the intensive mixing of particle streams. A comparison of the calculated particle size distributions and experimental data obtained from particle dynamics analysis (PDA) measurements proves the accuracy of the developed methodology. The elaborated model allows the final PSD of the powder in the spray towers to be predicted. [ABSTRACT FROM AUTHOR]