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How Does Moisturizer Work
保濕霜是怎樣發揮作用的
It’s the dead of winter. And… well, you know what that means: curling up with some hot cocoa,watching friends on Netflix and staring at your dry, cracked skin.
又要到數九寒冬了。你知道這意味著什么：蜷縮在被子里，端著一杯熱可可，瀏覽朋友圈，以及盯著自己干燥皴裂的皮膚頭疼。
Wait, what? When temperatures drop and heaters kick on, indoor air gets drier.
等等，你說什么？當氣溫下降，打開暖氣的時候，室內空氣會變得更加干燥。
That sends many of us scrambling for a moisturizer to ease the unsightly and irritating effects of dry skin.But what do these products actually do?
這讓我們許多人拿起保濕霜，緩解干燥皮膚的不適和刺激。但是這些保濕產品是怎樣發揮作用的呢？
As the name suggests, their job is to make your skin more moist. Skin dries out by a normal process with a fancy scientific name: transepidermal water loss.
就像它的名字，保濕霜的作用就是讓你的皮膚更加濕潤。皮膚正常的干燥過程有一個科學術語描述：經表皮水份丟失。
Or, if you like funny-sounding abbreviations, tewl.
或者，如果你喜歡發音風趣的縮寫tewl。
Blood vessels only supply moisture to the middle layer of skin, the dermis.From there, water moves outward through to the epidermis before it evaporates.
血管只為皮膚的中間層——真皮保濕。水分從真皮向外滲透到表皮，然后蒸發。
A moisturizer’s job is to trap or replenish the moisture in the epidermal layer.
保濕霜的作用就是將水分鎖在皮膚表層。
Moisturizers come in three varieties: occlusives, emollients and humectants.Most products you buy have a combination of some or all of these.
保濕霜共有三種：閉塞劑，潤膚劑和保濕劑。你購買的大部分保濕霜都含有其中兩種或三種成分。
Occlusives are the old school moisturizers,and they work in the simplest way possible.
閉塞劑是舊式保濕霜，以最簡單的方法發揮作用。
They form a barrier over the skin that water can’t penetrate, stopping evaporation and keeping your skin moist.
它們在皮膚上形成一層水不能穿過的壁壘，防止水分蒸發，保濕皮膚濕潤。
The best in the biz is petroleum jelly, sold as vaseline.It cuts tewl by 98 percent.The long carbon chains of the molecules that make up occlusives repulse water.
其中最有效的產品或許是凡士林。可以減少98%的水分流失。閉塞劑分子中的長碳鏈不親水。
The only problem? You don’t really want to walk around covered in vaseline.
唯一的問題？你不想涂著凡士林走來走去。
More popular these days are the emollients.
現在流行的大部分保濕霜是潤膚劑。
Instead of coating the skin, these are designed to penetrate, making skin feel softer and more flexible.
潤膚劑不是在皮膚表層形成一層保護膜，而是通過滲透讓皮膚更柔軟，更有彈性。
They are made from similar chemicals as occlusives: molecules with long fatty carbon chains like stearates and castor oil.
它們是用類似閉塞劑的化學物質制成的：有著長長的脂肪碳鏈的分子，就像硬脂酸鹽和蓖麻油一樣。
But they work differently.The outermost layer of your skin has a‘brick-and-mortar’ structure where the bricks are dead cells, called corneocytes, and the mortar is made of fatty layers of lipids. Corneocytes are linked by proteins that form a strong barrier between your body and the bacteria,microbes and toxins in the outside world.
但是它們的作用方式不同。皮膚的外層有一個“磚瓦加水泥”的結構，其中磚瓦就是死細胞，叫做角化細胞。水泥是由多層脂質組成的。角化細胞由蛋白質連接起來，在身體和外界的細菌，微生物以及毒素之間形成一層壁壘。
The ‘brick-and-mortar’ stacks are thicker in places like your palms, but thinner on softer skin like your face.
“磚瓦加水泥”結構在手掌等地方更厚，在膝蓋等柔軟的皮膚部位更薄。
When the moisture level in the air goes down,the protein links break apart and fractures develop between groups of corneocytes.
當空氣濕度下降的時候，蛋白質鏈接就會破裂，角化細胞之間就會出現皴裂。
Emollients get beneath the skin’s surface and fill in these gaps, keeping tewl under control and helping your skin feel smooth.
潤膚劑滲透到皮膚表層一下，填補這些空缺，控制皮膚失水，讓皮膚感覺光滑。
The third kind of moisturizers are humectants.
第三種保濕霜是保濕劑。
Broadly, these molecules help attract and retain moisture in the epidermis.
概括地說，這些分子幫助表皮吸收和保持水分。
Humectants help get the younger, moist cells towards the outer layer of skin, as well as reduce the flakiness of dry skin.
保濕劑可以讓更年輕，更濕潤的細胞到達皮膚外層，并減少干燥皮膚的成片脫落。
Humectants also stimulate the body’s natural production of ceramides,waxy molecules that reduce tewl.
保濕劑還可以刺激皮膚自然生成磷脂質，可以減少皮膚水分流失的蠟質分子。
So don’t leave your skin out to dry this winter.Grab some lotion and stay hydrated.Your corneocytes will thank you.
所以，這個冬季不要讓你的皮膚失水了。涂抹一些潤膚露來保濕。你的角化細胞會感謝你的。
