Based on increasing polarity, petroleum ether, chloroform, acetone, and water were used to extract the cut tobacco (Yunnan, China) components by extraction pot (RTN-6.0, Henan, China). The acetone ...

Polar Petroleum Corp., an exploration stage company, focuses on the exploration, development, and production of oil and natural gas in the United States. It owns interests in 29 oil and gas land ...

There's something about polar bears that's always puzzled the people who study them. How do they seem to repel snow? The animals spend their lives in cold climates, sometimes rolling around in ...

The system, known as a polar vortex, is forecast to bring subzero temperatures to the Midwest, Mid-Atlantic and deep into the South. And it looks as if we may get more arctic blasts in the coming ...

The first is the polar jet stream, a huge current of air that circles the globe between 50 and 60 degrees north latitude within the low-altitude troposphere, the same layer of atmosphere where ...

The polar vortex, a swirling mass of cold air located over the polar regions, is responsible for the cold. It's bringing extreme cold as far as the Deep South. Overnight lows will be well below ...

However, a deep freeze, thanks to the polar vortex dipping down from Siberia, is bringing an even harsher arctic blast to million Americans this week. Maps show what to expect as the cold front ...

What’s shaping up to be the most expansive polar vortex in over a decade is about to plunge much of North America, including nearly all of Canada, into the coldest temperatures the country has ...

Most of the US will enjoy milder temperatures on Thursday, but the warmup will be brief as a polar vortex will send temperatures tumbling below freezing for most of the nation starting this ...

A lobe of the polar vortex, a stormy ring that typically keeps the coldest air locked up near the North Pole, will dip southward into the United States this weekend into next week. Polar air ...