[化学論文のための英語講座] 第3回：受動態 Part2

(English version is here.)

前回に引き続き、受動態について説明を続けます。
受動態で動作主をはっきりさせる場合には前置詞が必要になり、「by」を用いることが多いです（それ以外の場合もあります）。前置詞の使い分けには、感覚的に掴んでいく部分が含まれています。理詰めで納得する方法より、直感的に感じたことを大事にしてください。

(1) 動作主が人間の時は「by」を使います。
The absolute stereochemistry was elucidated by Moore and coworkers in 1983.

(2) 動作主が手法または操作のような、動作を表す名詞（action noun）の場合にも「by」を用います。一方、動作主が機械または物質（object）であれば、「with」または動名詞である「using」をよく使います。「with」「using」には、「誰かが意図・目的をもって利用する」という意味合いが含まれておりますので、動作主である機械・物質が自ら意志を持っているわけではありません。

The extracts were analyzed by UV-vis spectrometry.
The extracts were analyzed with a UV-vis spectrometer.
spectrometry: 分光法（手法）、spectrometer: 分光光度計（装置（機械））

The reaction was quenched by addition of water.
The reaction was quenched with water.
addition of water: 水を加える（操作）、water: 水（物質）

以下に幾つか例文を示します。

a) The structure was determined by single crystal X-ray diffraction.
single crystal X-ray diffractionは、単結晶X線回折法という「手法」を意味するので、byが用いられます。

b) The compound was further purified by flash chromatography.
flash chromatographyは、フラッシュクロマトグラフィーという「分離手法」の１つですので、byが用いられます。

c) Compounds were purified using a high-performance liquid chromatography system.
動名詞である「using」を使う場合に前置詞は必要ありません。

(3) 動作主が物質（object）であっても、動作主である物質が自ら意志を持っている（自ら作用する）場合には「by」を用います。

a) 11-cis-Retinal is isomerized to all-trans-retinal by visible light.

b) Cyanoacrylate polymerization is typically initiated by atmospheric water.
この例文では、人間の意図がない、普遍的事実について述べています。Atmospheric waterが人間の意図とは関係なく作用するので、Atmospheric water は独立動作主です。

以上で受動態の科目は終了です。次回は「ミニコーナー」です。

Passive voice

When the actor is explicitly stated while using the passive voice a preposition is necessary. "By" is frequently used, but there are other cases as well. Grasping the use of prepositions is in part intuitive. Rather than just reasoning, keep intuition in mind as well.

(1) When the actor is a person, "by" is used.
The absolute stereochemistry was elucidated by Moore and coworkers in 1983.

(2) When the actor is a technique or operation, i.e., an action noun, "by" is used. On the other hand, if the actor is a machine or material, "with" or "using" are often used. "With" or "using" imply that someone possessing intention is behind the action, and the machine or material is not acting out of will or intent.

The extracts were analysed by UV-vis spectrometry.
(Spectrometry is an action noun.)
The extracts were analysed with a UV-vis spectrometer.
(A UV-vis spectrometer is a machine.)

The reaction was quenched by addition of water.
(Addition is an action noun.)
The reaction was quenched with water.
(Water is an object.)

Below are a few example sentences.

a) The structure was determined by single crystal X-ray diffraction.

b) The compound was further purified by flash chromatography.

c) Compounds were purified using a high-performance liquid chromatography system.

(3) In the case of the gerund "using", a preposition is unnecessary. Even if the actor is a material, if it is acting independently "by" is used. The following two examples function the same way.

a) 11-cis-Retinal is isomerised to all-trans-retinal by visible light.

b) Cyanoacrylate polymerisation is typically initiated by atmospheric water.

This completes the passive voice. We will post mini corner at next time.