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As it ages, white paper turns a distinctive yellow. But why? To find out, scientists artificially aged modern paper to reveal the changes on the molecular level. The research is in the journal Physical Review Letters.
隨著年代的久遠，白紙會明顯發黃。這是為什么呢？為了尋找答案，科學家人為地將現代的白紙老化以揭示其分子水平出現的變化。這項研究成果刊登在《物理評論通訊》上。
For 48 days, three unbleached paper samples aged rapidly in reactors that simulated different environmental conditions. The researchers then compared the artificially aged samples to the real deal: three pieces of paper crafted in 15th century Europe. This technique allowed them to gauge the types and amounts of changes going on.
在48天的時間里，三個原色紙張樣品在三個模擬不同環境條件的反應堆中迅速老化。然后，研究人員比較了人為老化的紙張和三張15世紀歐洲的紙片之間的區別。這種方式可以讓他們判斷出這些紙張在類型和數量上所發生的變化。
About 90 percent of the weight of old paper is cellulose, the sturdy material that makes up plant cell walls. But over time cellulose fibers oxidize. The process modifies parts of various molecules and turns them into what are called chromophores, which absorb light.
舊紙張重量的約90％來自纖維素，這是構成植物細胞壁的堅固材料。但隨著時間的推移，這種纖維素會逐漸氧化。這個過程會讓各種分子發生改性變化并將其轉化成染色體，而染色體會吸收光線。
White paper is white because it reflects all colors of light. Aging paper filled with chromophores reflects wavelengths that make it look yellow. The non-destructive technique used in this study could inform research to preserve and even whiten ancient texts and art. And give paper conservation abrighter outlook.
白紙之所以顯出白色因為它可以反射各種光線。而充滿了染色體的年代久遠的紙張則可以反射那些使它看起來顯示黃色的波長。這項研究中使用的非破壞性技術有助于研究如何保持甚至將古代典籍和作品重新亮白。這對紙張保護而言是一個光明的前景。
注：本文譯文屬可可英語原創，未經允許，請勿轉載。
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