Separation of 4-substituted 5-methylpiracetam stereoisomers on polysaccharide-based chiral stationary phases

Monitoring of stereoisomer content in samples containing chiral compounds with multiple chiral centers is an important and challenging task in chiral liquid chromatography. 4-Phenyl-5-methylpiracetam, containing two chiral centers, was used as model compound to explore the stereorecognition ability of polysaccharide-based chiral selectors. Initially, the chromatographic behavior of racemic 4-phenyl-5-methylpiracetam on nineteen commercially available polysaccharide-based chiral columns was tested with a mobile phase, consisting of a mixture of ethanol and n-hexane. The obtained results were analysed, and nine chiral phases were selected for further investigation of seven newly synthesized 4-substituted 5-methylpiracetam chiral separations. Our subsequent studies showed that chiral stationary phases based on amylose tris(5-chloro-2-methylphenylcarbamate) and amylose tris[(S)-α-methylbenzylcarbamate] posess higher ability for chiral recognition of stereoisomers of the studied analytes

Increased Temperature and Intensification of the Urban Heat Island: Implications for Human Comfort and Urban Design

The predicted rise in air temperatures due to climate change is exacerbated in urban areas by the heat island effect, which is also predicted to increase. The combined effect, in a temperate climate, will have some benefits in the cooler seasons but in the summertime will increase heat stress and the energy used for cooling. This paper refers to research results showing how changes to urban design can improve thermal comfort. It also shows how changing the albedo of the surfaces of the buildings can reduce the impact of solar radiation by reducing the radiant temperature of the environment. The benefits of increased vegetation within the urban environment are shown from measurements in the context of the urban London environment