Writing a paper, materials and methods – day 1: the passive voice and linking wordsFree Preview
Whichever language you would normally write up your research in, it is probably best to start with materials and methods. Today the Journal will look at two aspects of writing:
- Writing in the passive voice / tense
- Linking words for writing a process
FIrst, we will look at the passage below.
2. Material and methods
2.1. Materials and reagents
Paper mill sludge (PMS) samples were collected from two different local paper mill plants of Bangladesh as calcium-containing source materials. Hydrochloric acid (37%) and sodium hydroxide (CAS: 1310-73-2, Purity approx. 98.0%) were purchased from Merck, Germany and DAEJUNG, Korea, respectively. Distilled water was used throughout the work as needed. All chemicals were utilized without further purification.
2.2. Synthesis methods
First of all, the collected PMS was mixed with distilled water to prepare a homogeneous mixture which was then filtered by a suction pump. After filtration, the mixture was dried in an electric oven at 60–65°C for 2 h in air until complete removal of water. Then it was crushed manually by using a ceramic mortar/pestle. Afterwards, a certain amount of dry-solid sludge was taken in a beaker, mixed with distilled water, and then stirred for 45 min. Meanwhile, 1.0 M HCl was added in solution to dissolve all the calcium contents in the aqueous medium, where pH of the sludge solution was maintained in the range of 2.25–2.50. After filtering the acidic solution, the filtrate part (very clear) was taken under base treatment by NaOH, maintaining a pH above 13.0 and the product formation/precipitation was seen to start within few minutes. The raw and synthesized samples were safely stored into the sample vials for various characterizations(a representative photograph of these samples is shown in electronic supplementary material, figure S1).
This extract is taken from: Molla MR et al. 2022 Facile extraction and characterization of calcium hydroxide from paper mill waste sludge of Bangladesh. R. Soc. Open Sci.9: 220681.https://doi.org/10.1098/rsos.220681
The passive voice
Writing in the passive voice is common in science to avoid putting the authors at the centre of the study. Instead the subject of the experiment becomes the focus.
Writing in the passive means the subject is acted upon; it, he or she receives the action expressed by the verb. The agent performing the action may appear later or may be omitted. When writing for science the agent will be omitted altogether. It is assumed that the actions are being done by the authors.
I took my dog for a walk.
The dog was taken for a walk.
Either the present or the past tense can be used when writing in the passive form, but as authors will normally be describing an experiment they carried out in the past, then the past tense will be used.
When writing in the passive voice the sentence is normally flipped in order, with the subject appearing at the start of the sentence, and being acted upon.
We know from the above text that in the recent past the authors carried out an experiment on paper mill sludge samples. We know that the authors went to two different sites to collect the samples. They wrote:
Paper mill sludge (PMS) samples were collected from two different local….
The samples become the focus and have the action done to them. Look at other examples in the first paragraph of writing in the passive form:
Hydrochloric acid (37%) and sodium hydroxide (CAS: 1310-73-2, Purity approx. 98.0%) were purchased from Merck, Germany…
Distilled water was used throughout…
All chemicals were utilized without…
Have a look through the second paragraph of the extract and see if you can identify the rest of the examples of the passive form.
Linking words for describing processes
When describing a process it is necessary to describe the order in which things happened. For this we can use linking words. For example:
- First, second, third, etc.
- Firstly, secondly, thirdly, etc.
- First of all, initially, at the beginning
- Then, next, after this, subsequently,
- Prior to this, before this
Have a look through the second paragraph of the extract to see how the linking words for describing the process are used: First of all, After filtration, Then it, Afterwards, Meanwhile, etc.
Further study for this week
Try using the advice that comes with the Journal this week to write up a materials and methods section from a recent piece of research you have been involved with. And please try today’s quiz below to test your understanding.