Thixotropic gel is an inert (nonreacting) synthetic substance in the bottom of certain tubes. When a specimen in a gel tube is centrifuged the gel undergoes a change in viscosity and moves to a position between the cells and the serum or plasma, forming a physical barrier between them. This separation prevents the cells from continuing to metabolize substances such as glucose in the serum or plasma.
Placement of Citations. 1  Place a citation as close to the quoted or paraphrased material as possible without disrupting the sentence. 2  When material from one source and the same page numbers is used throughout a paragraph, use one citation at the end of the paragraph rather than a citation at the end of each sentence.
Citing Articles in APA Style. These examples show how to create citations for articles from different sources. These types of citations would go on References page at the end of a paper or presentation. To see how to cite a source in the body of the paper or presentation, click on the In-Text Citations tab above. Journal article from a database or journal's website. Author Last Name, First Initial.