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Searching RAPRA Polymer Library Using the Controlled Term Thesaurus

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"A rose by any other name may smell as sweet" but could you order one by telephone from a florist if you didn't know what it was called? This may seem a trivial example, but it shows the importance of using the correct terminology.

Searching a database is basically a process of matching your query terms against the words in a document. Simply put, if the terms don't match, then the document will not be retrieved, regardless of how well the subject of the document matches the query. Therefore, one of the greatest barriers to successfully finding relevant information is the difficulty of choosing the correct terminology.

Lists of standardized subject headings, structured thesauri and fielded searching (e.g., title, author, descriptors) were created to alleviate this problem. There are several reasons why these tools were created.

• To ensure that all materials about the same topic were found either on the same shelf (physically storing books in a library) or in an online database.
• To highlight important concepts rather than those merely incidental to the work.
• To ensure that the same information was found for each work, and that it was put in the same place. So that someone searching for papers by an author named John River, for example, would not find them mixed with geographical tracts on the River Severn.

The correct use of indexing vocabularies (thesauri or descriptors) increases the precision of the search and minimizes the chance of false retrievals. Thesauri can also address three language problems that can result in poor relevance, namely: polysemy, synonymy and ambiguity.

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Polysemy

Most words in English -- and in some other languages -- have more than one meaning. For plastics and rubber technology, this is particularly the case for abbreviations. For example, if we are searching on ABS, are we looking for articles on the material "acrylonitrile-butadiene-styrene terpolymers" or are we interested in "anti-braking systems"? Another illustrative abbreviation would be for the chemical polyethylene terephthalate. In the plastics industry this is often known as PET. However, PET can also represent a number of acronyms. For example, the Website Acronym Finder (http://www.acronymfinder.com) lists the following as some of the abbreviations for PET.

PET Performance Evaluation Test

PET Positron Emission Tomography

It also lists the acronym PETE as the acronym or abbreviation for polyethylene terephthalate. Both PET and PETP are given as abbreviations for polyethylene terephthalate on the Abbreviations of chemical compounds (Abkürzungen chemischer Verbindungen) Website (http://www.chemie.fu-berlin.de/cgi-bin/abbscomp).

In the context of the RAPRA (Dialog File 323) database, the approved descriptor abbreviation is PETP. This choice by Rapra removes the ambiguity of the abbreviation PET and also allows the use of "pet" as in the case of a domesticated animal.

Similarly, PC is not an allowed Rapra Descriptor for Polycarbonate as it could equally well stand for Personal Computer. Equally, POM is not an allowed Rapra Descriptor as it could stand for either Polyoxymethylene (also known as Polyacetal) or Polarized Optical Microscopy. Using the Rapra Thesaurus will therefore allow you to discover which abbreviations are allowed and will also tell you (generally speaking) what it represents.

Search Tip — If you are not sure how a term may have been indexed you can always search on that term using free text (i.e., the basic index) and then look at the descriptors given for the first few records found. Using the example above, if we search on "PET" in the basic index, it will find records where PET exists in such fields as the Title or Abstract. Browsing some of the descriptors will then show that PETP or POLYETHYLENE TEREPHTHALATE are the preferred terms.

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Synonymy

Many words represent the same concept, although they may do it with different shades of meaning. Take the words "recyclate," "scrap," and "reclaim," or "X-ray scattering," and "X-ray diffraction." If I look for X-ray diffraction, but the term used is X-ray scattering, I will not retrieve relevant materials I might otherwise have found. A thesaurus will show which is the preferred term or which terms have allowed synonyms and what these synonyms are. It can also show broader and narrower terms. The Rapra Thesaurus lists Descriptors (or Index Terms), Identifiers (or Non-Polymer Terms for chemicals that are not polymeric) and Geographic Locations (countries or geographic regions) and shows allowed terms, preferred terms, broader terms, narrower terms and related terms.

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Ambiguity

If we return to our example of PET (or PETP) or pet, we can see that what differentiates these meanings is their context. If searching for articles discussing the material polyethylene terephthalate, we would not be interested in articles discussing another plastic that is used, say, as the packaging material for pet food. Using the preferred form PETP (or the full name polyethylene terephthalate) ensures that we only retrieve articles on polyethylene terephthalate. Or searching on the word "association" would retrieve both articles on trade association and on molecular association.

A search on wristwatches offers another example. If we search on the word WATCH in the title field, we would find a number of records:

• WEB.WATCH DIRECTORY
• ADHESIVE, AND ADHESIVE-FIXED BODY, ELECTRONIC APPARATUS AND WATCH
• EU WATCH - CONSTRUCTION PRODUCTS DIRECTIVE UPDATE
• NORTH AMERICA WATCH
• EASTMAN CEO ON THE WATCH AS PETP SHAKEOUT TAKES SHAPE
• PRODUCERS TRY FOR MORE PRICE RISES - BUT WATCH FOR RIPPLES FROM THE ASIAN MONEY CRISIS
• GROWTH LOOKS EXCEPTIONAL, BUT WATCH FOR RESIN SHIFT
• PRICE WATCH
• FLAME LAMINATORS WATCH OUT - YOU ARE ON THE LIST!
• PS PRODUCERS WATCH FALLING STYRENE PRICE

Of the ten records above, nine use WATCH as a verb and only the second record is about a wristwatch.

However, if we search on WATCH in the descriptor field, the result is significantly different.

• ALLIANCE, A CENTRE OF EXPERTISE IN APPLICATIONS OF METAL INJECTION MOULDING
• ELECTRIC CURRENTS
• MICRO MIRACLES
• MICRO INNOVATION
• MICRO INNOVATION
• GETTING A DOSE OF MEDICINE
• ADHESIVE, AND ADHESIVE-FIXED BODY, ELECTRONIC APPARATUS AND WATCH
• SUPER MICRO SIZED GEARS
• LEADING EDGE THROUGH NEW TECHNOLOGY
• SMALL BUT PERFECTLY FORMED
• PERFECT FINISH

The titles and records generated using this strategy are all about wristwatches or parts that go into wristwatches, such as gears or watch glass. Hence, using the Rapra Descriptor WATCH enabled us to retrieve relevant records and avoid irrelevant records.

The list of Descriptors that Rapra uses can be found in the Polymer Library (Rapra Abstracts) Thesaurus, which is a collection of terminology used in the rubber and plastics industry. This thesaurus was started in January 1993 and, as mentioned above, contains a list of Descriptors, Identifiers (Non-Polymer Terms for chemicals that are non-polymeric) and Geographic Locations (countries or geographic regions), together with synonyms, broader terms, narrower terms, related terms and classification codes, which can greatly assist in building a search strategy. The Thesaurus is available for free at http://www.polymerlibrary.com/thesaurn.pdf.

For additional information and search tips on the Rapra database, visit the Smithers Polymer Library Website.

For further help in searching the database, please contact the Dialog Knowledge Center at , or 1-800-334-2564 or 00-800-33-34-2564.

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