英语听力文摘 English Digest 254、无霜冷冻

　　Frost-free Freeze Physics
昇華是指一种物质从固态不经过液态直接转化为气态的过程，是物质在温度和气压低于三相点的时候发生的一种物态变化。与昇華相反的过程称做凝華，指物质从气态直接变成固态。這樣的例子有結霜。昇華是吸熱的反應，所需的熵是汽化熱和熔化热之和。
Frost-free freeze physics--it's more than a tongue-twister(绕口令).
“Sublimation¹” is when ice turns into a gas without passing through the usual intermediary liquid state. If you leave your ice cubes in back of the freezer for a month or so, you might notice they start to shrink. That’s because they are sublimating²: the ice is turning to water vapor³ even though it never melted.
But I tried this experiment myself and my ice cubes never shrunk! All I got was a cold head! Then, physicist⁴ John Carini explained to me that it only works if you have a frost-free freezer.

　　Why is that?It’s in the nature of sublimation. When we say that ice can turn into water vapor, what we mean is that (1)fast-moving water molecules⁵ can actually (2)fling themselves off the surface of the ice cube and into the surrounding air. That’s what evaporation⁶ means. The more molecules that can free themselves of the ice this way, the more the ice has turned into vapor.
But wait!In order to do that, the air around the ice cube can’t (3)be saturated⁷ with water already. If it is, there’s no room for more molecules and evaporation can’t take place. Frost-free freezers keep the air from becoming saturated so that it won’t freeze on the walls. But that also means ice-cubes can sublimate⁸ nonstop!
Notes:
(1)fast-moving adj.移动迅速的
Candy as a fast-moving consumer goods, products price is not high, still attracts the public consumption.
糖果作为快速消费品，公司产品单价也不高，仍然吸引着大众消费。
(2)fling off发出；甩掉；挫败
It's good to fling off heavy clothing now that spring is here.
春天来了，脱掉厚厚的棉衣是适时的。
(3)be saturated with 被…所饱和；充满着
Permit this entire period of time to be saturated with BLUE LIGHT.
这段期间，让蓝色之光充满你的整个存在。

1 sublimation   

n.升华，升华物，高尚化

参考例句：

• Presently, entrepreneurship, innovation and excellence-creating are the sublimation of the spirit. 在新的历史条件下，“创业创新创优”的三创精神是新时期江苏人文精神的升华。 来自互联网
• Luleng deems that public will is a sublimation of human's free volitions. 摘要卢梭认为，公意就是人类自由意志的升华。 来自互联网

2 sublimating   

v.（使某物质）升华( sublimate的现在分词 )；使净化；纯化

参考例句：

3 vapor   

n.蒸汽，雾气

参考例句：

• The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
• This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。

4 physicist   

n.物理学家，研究物理学的人

参考例句：

• He is a physicist of the first rank.他是一流的物理学家。
• The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

5 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

6 evaporation   

n.蒸发，消失

参考例句：

• Be careful not to lose too much liquid by evaporation.小心不要因蒸发失去太多水分。
• Our bodies can sweat,thereby losing heat by evaporation.我们的身体能出汗，由此可以蒸发散热。

7 saturated   

a.饱和的，充满的

参考例句：

• The continuous rain had saturated the soil. 连绵不断的雨把土地淋了个透。
• a saturated solution of sodium chloride 氯化钠饱和溶液

8 sublimate   

v.(使)升华，净化

参考例句：

• We need sublimate water for our experiment.我们的实验需要纯净化的水。
• Her sublimate future husband will be tall,dark,and handsome.她理想化的未来丈夫将是身材高大，皮肤浅黑，相貌英俊。