When to cite

Technical Citations: Chemical Engineering

 Proper citation of source material serves two purposes: it makes clear the authorship of the information and ideas, and it aids the reader in locating original material in case they wish to investigate the cited information further.  It is also a professional responsibility. Furthermore, failure to do so is plagiarism.  Listed below are the three most common lapses.

Case 1. Paraphrasing information and conclusions that are derived from elsewhere What is paraphrasing?  The definition from The Merriam Webster Dictionary states “a restatement of a text giving the meaning in different words”[1].  Please note that “different words” does not imply that simply switching the sequence of words in a quote is sufficient to be a paraphrase.  That is still essentially a direct quotation and must be attributed as such.  What follows in an example of  (example taken from “Supervisory Control System Development for Research Fermentation Process at Glaxo SmithKline”, Phase 4 report”, CHE 451, Sp 2001)

During aerobic respiration of E. coli, glucose is metabolized into acetic acid, lowering the pH within the fermentor. After depletion of the glucose, the bacteria begin to catabolize amino acids for energy and carbon and give off the nitrogen as ammonia.⁷ This step is signaled by a rapid increase in DO, as cellular respiration activity slows down, and an increase in pH, as ammonia levels increase. As a result, nutrient feeding can be regulated through feed-back control of changing values of pH during the fermentation run. ⁸ Glucose is substituted for acid in the acid reservoir; therefore, as the pH increases above 7.2, the controller signals to begin acid flow into the fermentor. Instead of acid, glucose is fed into the fermentor, and the cells receive the nutrients they need in order to continue normal cellular respiration.

Please note that the citations are sprinkled throughout the paragraph, not collected at the end of the paragraph.  Unless otherwise stated, a citation at the end of a sentence or paragraph only applies to that sentence.

Case 2.  Using data derived from elsewhere

Table 1 lists the cost of the raw materials required for this process.  As is indicated, the dominant raw material cost comes from process sulfuric acid ($2,102,536) due to its high unit cost.  Other significant contributors to the total raw material cost include cane molasses and calcium carbonate.  However, the total raw material costs may vary due to the both fluctuation and varied price of cane molasses since the cost of cane molasses varies depending on providers and is heavily dependent on the climatic conditions.

Table 1—Raw Material Costs[2]

Please note that the table contains no references whatsoever, even though it is clear that the authors did not generate the raw material costs themselves.  A more appropriately cited table follows:

Table 2: Strains used in this study[3]

Bacterial strain	Genotype/Phenotypea	Source or reference
E. coli DH5	supE44, lacU169(80lacZM15), hsdR17, recA1, endA1, gyrA96, thi-1, relA1	Stratagene
E. coli S17-1pir	recA, thi, pro, hsdR, M+, RP4:2-TcR:Mu:KmR,Tn7TpRSmR, pir lysogen	[deLorenzo, 1993 ]
P. putida KT2440	hsdR	[Franklin, 1981 ]
P. putida EM2839	hsdR, Pob–	This work
P. putida EM2840	hsdR, Pob–, mini-Tn5 aphA lacIq Ptrc pchCF phbz	This work
P. putida EM2878	hsdR, Pob–, mini-Tn5 aphA lacIq Ptrc pchCF phbz, mini- Tn5 tet nahR Psal tmoABCDE	This work

 

The important point here is that the source of each datum (and in this case, each strain) is referenced. In the raw material costs table, it would have been appropriate to refer to the source for the unit cost of each raw material.

Case 3.  Direct quotation

There are times when the use of direct quotation is useful and appropriate.

Ethical considerations are infrequently included in engineering curricula, so it should not be surprising that students are uncertain how to proceed when confronted with an ethical dilemma, or even to recognize such situations.  It is suggested that any discussion of engineering ethics begin with the relevant code of ethics for the profession.  Chemical engineering practice, for example, is governed by the code of ethics set forth by the American Institute of Chemical Engineers, which states that

Members of the American Institute of Chemical Engineers shall uphold and advance the integrity, honor, and dignity of the engineering profession by: being honest and impartial and serving with fidelity their employers, their clients, and the public; striving to increase the competence and prestige of the engineering profession; and using their knowledge and skill for the enhancement of human welfare. [4]

The direct quotation is sufficiently lengthy so that italics and indentation are used to set it off from the rest of the document.  The preamble is my own, so there is no additional reference required.

The technical literature is another indication of the standards and expectations of the engineering community regarding proper citation practice.  Again, if you are unsure of how to handle certain information, Dr. Bullard is available to help.

[1] The Merriam Webster Dictionary, (1974), page 506

[2] Taken from “Citric Acid Plant Design: Phase III”, CHE 451, Spring 2001

[3] Miller, E. S. and S. W. Peretti, “Toluene bioconversion to p-hydroxybenzoate by fed-batch cultures of recombinant Pseudomonas putida”, Biotechnol. Bioeng. 77, (2002) 340 – 351

[4] http://www.aiche.org/about/ethicscode.htm