This work is focused on the development and evaluation of completely natural anti-aging creams, with the aid of the experimental design. Model formulations, differing in the content of emollients (10%/15%/20%) and emulsifier (1%/2%/3%) and containing the Acmella oleracea extract as a model anti-aging active were prepared by the cold process and evaluated regarding rheological behavior (con-tinuous rotational and oscillatory tests) and physical stability (dynamic-mechanical thermoanalysis-DMTA test). To study the influence of varied formulation parameters and their interaction on the critical rheological characteristics of the developed creams, a D-optimal design within the response surface method was applied. The data acquired from rheological characterization revealed favorized pseudoplastic (shear-thinning) flow behavior with the yield point, and dominating elastic behavior (storage modulus G' > loss modulus G") in both, amplitude and frequency sweeps, which together with a rather small and constant structural change obtained in the DMTA test indicated satisfying overall physical stability of formulated creams. The results of D-optimal design showed a significant individual, as well as a mutual effect of the tested formulation factors (emollient concentration, emulsifier concentration) affecting critical quality attributes (apparent viscosity, yield point, flow point, G', G", structural change) of developed anti-aging creams. Based on optimization results, the model formulation containing 20% of the emollient mixture and 2% of the emulsifier was selected as preferred in terms of required rheological properties and, thus, desired stability and quality, and it could be considered as a promising candidate worth exploring further for efficacy and in vivo skin performances.

The objective of this paper is to point out the significance of the natural lignite resources in the region of Kosovo and Metohija and to consider their influence on the environment of the said part of the territory of the Republic of Serbia. The region of Kosovo and Metohija is extremely rich in lignite. It makes up 76% of the total coal reserves in Serbia and it is the third biggest region in Europe regarding the coal reserves. Lignite is burned in the existing thermal power plants in Kosovo and Metohija, and the construction of the additional blocks is being planned at the moment. Lignite reserves are so immense that on one hand they enable the energy independence, but on the other hand the overall negative impact of reliance on lignite must be taken into account, especially since the existing thermal power plants operate according to the outdated environmental standards, producing large emissions of air pollutants (harmful gases resulting from lignite combustion in thermal power plants) that have negative impact on health. In order to reduce the environmental pollution that such thermal power plants create, operating of the said power plants needs to be adjusted to the stricter standards in compliance with the legal requirements and the Industrial Emissions Directive of the European Union.