Knife Design and Cut Types
Generally, knives are characterized by the profile of the knife blade, which falls under the categories of planar concave, wedge shaped or chisel shaped designs.
Planar concave microtome knives are extremely sharp, but are also very delicate and are therefore only used with very soft samples. The wedge profile knives are somewhat more stable and find use in moderately hard materials, such as in epoxy or cryogenic sample cutting. Finally, the chisel profile with its blunt edge, raises the stability of the knife, whilst requiring significantly more force to achieve the cut.
For ultramicrotomes, glass and diamond knives are required, the cut breadth of the blade is therefore on the order of a few millimetres and is therefore significantly smaller than for classical microtome knives. Glass knives are usually manufactured by the fracture of glass bars using special "knife-maker" fracturing devices. Glass knives may be used for initial sample preparations even where diamond knives may be used for final sectioning. Glass knives usually have small troughs, made with plastic tape, which are filled with water to allow the sample to float for later collection. Diamond blades may be built into such an existing trough, allowing for the same collection method.
Read more about this topic: Microtome, Microtome Knives
Famous quotes containing the words knife, design, cut and/or types:
“When she, and though some said she played
I said that she had danced heart’s truth,
Drew a knife to strike him dead,
I could but leave him to his fate;
For, no matter what is said,
They had all that had their hate....”
—William Butler Yeats (1865–1939)
“For I choose that my remembrances of him should be pleasing, affecting, religious. I will love him as a glorified friend, after the free way of friendship, and not pay him a stiff sign of respect, as men do to those whom they fear. A passage read from his discourses, a moving provocation to works like his, any act or meeting which tends to awaken a pure thought, a flow of love, an original design of virtue, I call a worthy, a true commemoration.”
—Ralph Waldo Emerson (1803–1882)
“Becoming more flexible, open-minded, having a capacity to deal with change is a good thing. But it is far from the whole story. Grandparents, in the absence of the social institutions that once demanded civilized behavior, have their work cut out for them. Our grandchildren are hungry for our love and approval, but also for standards being set.”
—Eda Le Shan (20th century)
“Science is intimately integrated with the whole social structure and cultural tradition. They mutually support one other—only in certain types of society can science flourish, and conversely without a continuous and healthy development and application of science such a society cannot function properly.”
—Talcott Parsons (1902–1979)