The low density of the gas hampered many attempts to detect it in the past.

过去许多探测低密度气体的努力都受到了阻碍。

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Scientists predicted that the gas would have a high temperature and so it would primarily emit low-energy X-rays. But its very low density made observation difficult.

科学家们预言气体温度可能很高于是会主要发射出低能的X射线。但是其过低的密度给观测带来困难。

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Membrane separation technology is widely adopted in the gas separation application due to its special separation efficiency, low weight and high pack density.

膜分离技术广泛应用于气体分离是因为它的特殊分离效率、低质量和高填充密度。

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Hyperpolarisation not only compensates for the low density of the gas (the 3He is 10, 000 times more polarised than the hydrogen in water), it also allows images to be taken rapidly enough to avoid any blurring due to a patient's natural tendency to breathe.

ECONOMIST: Medical imaging

In one recent year, the complex boasted an annual production of 1, 785 million pounds of caustic soda, 2, 135 million pounds EDC, 1, 266 million pounds PVC suspension resin, 840 million pounds VCM, 3, 411 million pounds ethylene gas, 1, 484 million pounds High Density Polyethylene, 582 million pounds Linear Low Density Polyethylene, and 1, 495 million pounds polypropylene.

FORBES: The Gluttons of Natural Gas