32 Science Research Writing mechanism only vaguely or empirically defi ned, and provide little mechanistic insight. Th e purpose of this paper is to provide a framework for defi ning 'charge-transfer' and 'non-charge-transfer' processes, and to illustrate how they are diff erent. We investigate why charge-transfer models have diffi culty modelling non-charge- transfer eff ects, and walk through several examples including the ALS model for oxygen reduction on a porous mixed-conducting oxygen electrode. We then review a recent study of linear AC polarization of La1-x Srx CoO3-5 (LSCO) electrodes on ceria that corroborates the ALS model, and demonstrates the importance of O2 surface exchange and diff usion. Th is study shows that the electrode reaction extends up to 20 microns beyond the electrode/ electrolyte interface, implying that electrode polarization is better described by macroscopic thermodynamic gradients than as an 'overpotential'. Now do the same for the Introductions of your target articles. You should fi nd that most Introductions begin with item 1, that the order of the model components is usually fairly reliable (although items 2 and 3 can occur more than once) and that almost all Introductions fi nish with number 4. We have, therefore, answered the three questions we set at the beginning of this unit: • How do I start the Introduction? What type of sentence should I begin with? • What type of information should be in my Introduction, and in what order? • How do I end the Introduction? 1.4 Vocabulary You now need to collect vocabulary for each part of the Introduction model. Th e vocabulary in this section is taken from over 600 research articles in diff erent fi elds, all of which were written by native speakers and published in science journals. Only words/phrases which appear frequently have been
Introduction — Vocabulary 33 included; this means that the vocabulary lists contain words and phrases which are considered normal and acceptable by both writers and editors. We will look at vocabulary for the following areas of the model: 1. ESTABLISHING SIGNIFICANCE Th is includes phrases such as Much research in recent years. A good list of commonly used words and expressions will encourage you to include this in your fi rst sentences. 2. PREVIOUS AND/OR CURRENT RESEARCH AND CONTRIBUTIONS Th is includes all past tense verbs describing what researchers did, i.e. calculated, monitored, etc. Instead of just using did, showed and found, you oft en need to be more specifi c about what a researcher actually 'did'! 3. GAP/PROBLEM/QUESTION/PREDICTION Th is includes ways to say exactly how previous and/or current research is not yet complete or has not addressed the problem your paper deals with, e.g. However, few studies have focused on... 4. THE PRESENT WORK Th is may include your purpose, your strategy and the design of your paper, using language such as the aims of the present work are as follows: VOCABULARY TASK Look through the Introductions in this unit and the Introductions of your target articles. Underline or highlight all the words and phrases that you think could be used in each of the four areas given above. A full list of useful language can be found on the following pages. Th is includes all the appropriate words and phrases from the Introductions in this unit, together with some other common ones which you may have seen in your target articles. Underneath each list you will fi nd examples of how they are used. Read through the list and check the meaning of any you don't know in the dictionary. Th is list will be useful for many years.