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Based on data collected in 20 A-level high-rise commercial concrete buildings in Hong Kong, the research successfully established a probability density function model, which is used to describe the carbon emissions profile of a commercial building. Results indicate that the superstructure of a commercial building, on average, had a footprint of 226.65 kg CO2/m2 and 10.6 kg CO2/m2 separately in the material use stage and transportation stages. It also evaluates the carbon emissions of various building elements and divides them into three levels according to the magnitude of their contribution. The results show that upper floor construction and external wall in Tier 1 contribute nearly 80% of emissions and should be of great concern. In addition to the probability density function model, a regression model was also successfully established in the study to predict carbon emissions. Research has shown that building layers and gross floor area can predict carbon emissions per unit area, and there is a positive relationship between the independent variable and the dependent variable. The regression model can help building designers determine design options to reduce carbon emissions in the early stages of design.

We report on a method for the determination of twelve herbicides using solid–liquid–solid dispersive extraction (SLSDE), followed by dispersive liquid-liquid micro-extraction (DLLME) and quantitation by gas chromatography with triple quadrupole mass spectrometric detection. SLSDE was applied to the extraction of herbicides from tobacco samples using multi-walled carbon nanotubes (MWCNTs) as clean-up adsorbents. The effect of the quantity of MWCNTs on SLSDE, and of type and volume of extraction and disperser solvents and of salt effect on DLLME were optimized. Good linearity is obtained in the 5.0 - 500 μg kg−1 concentration range, with regression coefficients of >0.99. Intra-day and inter-day repeatability, expressed as relative standard deviations, are between 3 and 9 %. The recoveries in case of herbicide-spiked tobacco at concentration levels of 20.0, 50.0 and 100.0 g kg−1 ranged from 79 to 105 %, and LODs are between 1.5 and 6.1 μg kg−1. All the tobacco samples were found to contain butralin and pendimethalin at levels ranging from 15.8 to 500.0 μg kg−1.