2020年经济学人司法鉴定(2)（打印版）

The chains are held together by bonds between the carbon atoms.

碳链是由碳原子间的键连接在一起的。

These are of two varieties, known as single and double bonds.

化学键有两种，单键和双键。

Single bonds are, in chemistry-speak, saturated, and double bonds unsaturated.

用化学术语讲，单键是饱和的，双键是不饱和的。

By extension, molecules with one or more double bonds in them are also referred to as unsaturated,

由此引申义，含有一个或多个双键的分子也被称为不饱和分子，

while those with only single bonds are called saturated.

而只有单键的分子被称为饱和分子。

Unsaturated bonds are more reactive, and it is here that ozonolysis does its work.

不饱和键反应性更强，这就是臭氧分解的作用。

Ozone breaks up triglycerides at their double bonds, with one or more of the ozone's oxygen atoms

臭氧分解甘油三脂的双键，一个或多个臭氧氧原子附着在碳链上，

becoming attached to the carbon chain, to create new chemical species.

形成新的化学物质。

In principle, this should result in a gradual loss of unsaturated triglycerides

原则上，这将导致不饱和甘油三脂的逐渐损失

and a concomitant rise in the reaction products of ozonolysis.

以及臭氧分解反应产物的增加。

And that, in practice, is what Dr Hinners and Dr Lee found.

而这正是Hinners博士和Lee博士所发现的。

They asked three volunteers to leave their prints on a number of glass slides. They then tested some of those slides immediately,

他们请三名志愿者在一些载玻片上留下他们的指纹。然后他们立刻对其中一些进行检测，

using a sensitive analytical technique called matrix-assisted laser desorption/ionisation (MALDI)

他们使用一种称为基质辅助激光解吸/电离（MALDI）的灵敏分析技术

to produce a spectrum of the prints' chemical contents.

来产生指纹的化学成分光谱。

The other slides they left exposed to the air for between one and seven days, testing them at regular intervals.

他们将其他剩下的载玻片暴露在空气中1到7天，每隔一段时间测试一次。

As they suspected, as time progressed the ratio of saturated to unsaturated triglycerides in a sample rose,

正如他们猜想的那样，随着时间的推移，样品中饱和甘油三脂与不饱和甘油三脂的比率上升，

and so did the quantities of two characteristic products of ozonolysis—aldehydes and Criegee ions.

臭氧溶解的两种典型产物——醛类和Criegee离子的数量也是如此。

On the basis of what is, admittedly, a small sample, Dr Hinners and Dr Lee therefore think

诚然，Hinners博士和Lee博士因此认为

that MALDI analysis of fingerprint residues should prove accurate enough to date to within 24 hours

MALDI对指纹残留物的分析应该足够准确，

when a fingerprint under a week old was made—and thus whether it is associated with a crime temporally, as well as spatially.

可以在24小时内对一周以内的指纹进行分析——以及它是否因而与犯罪在时间上和空间上都有联系。