Handling and Use


Introduction DiATOME is the leading manufacturer of diamond knives for ultramicrotomy in bio logical and materials research, with many years experience. The expertise obtained in collaboration with our customers enables us to offer you the highest quality knives available in the market today. This manual was written in order to allow you an easy handling and use of our knives. Please contact us, if you should need any assistance or if you have any special requirements in your ultramicrotomy applications. We are only a phone call or an email away and look forward to hearing from you.


Handling A diamond knife is not as fragile as you might think. Taking into account the vast array of soft and hard specimens it cuts successfully, the diamond knife cutting edge is quite durable.


With proper care and handling, a DiATOME knife can withstand a great deal of use. However, in order to avoid any unfortunate mishaps, the following precautions should be taken when receiving the knife:


• Inspect the two securing stickers on the knife box and inform us if they have been cut or damaged.


• Ask your receiving department not to open the box. • When unpacking the knife, care should be taken not to touch the cutting edge.


• Once the knife is unpacked it is ready for use and does not need initial cleaning.


Preparation before sectioning A perfect section ribbon can only be obtained from a well trimmed block. The upper and the lower side of the block must be parallel to the knife edge. The block should not be too wide because this would substantially increase the cutting pressure. This may result in «chatter».


We have found that the best trimming results of biological and materials research samples, at room- and cryo temperatures, are obtained with our diamond trim blades trim 45 (ord. no. DTB45), trim 20 (ord. no. DTB20), and trim 90 (ord. no DTB90). See our knife brochure for more information.


Caution


If trimming is done with a razor blade, always use a fresh, degreased blade of good quality. If the razor blade is old and damaged, it has tendency to leave steel particles on the sample block. Upon sectioning, these particles will cause damage to the diamond knife’s cutting edge. If a sample block is precut with a glass knife, use only a clean new portion of the cutting edge. This will reduce the risk of glass particles sticking on the sample block. Avoid during the entire preparation of the sample blocks the embedding of hard particles from pipettes, razor blades, glass knives, etc.


Sectioning at room temperature


The quality of sections will be determined by a number of factors. The following points should be checked before commencing sectioning:


• Set the clearance angle and the cutting speed as indicated on the guarantee card.


• Tighten all of the screws in the sample block holder, the knife holder, etc.


• Align the block (with the backlight on) parallel to the cutting direction.


• Align the block (with the backlight on) parallel to the cutting edge. • Align the lower side of the block (with the backlight on) parallel to the cutting edge.


The water in the boat should be level with the cutting edge and give a good reflec tion. Exception: For the sectioning of hydrophilic embedding materials we recom mend lowering the water level to a concave shape.


To avoid difficulties during sectioning and extend the life of a diamond knife, the following should be kept in mind:


• The sample block should be fully polymerized. • Do not add solvents (i.e. acetone) to the distilled water in the boat. They may dissolve the sealing material between the knife and the boat. If the adding of solvents is unavoidable, ask us for sealing the knife with an epoxy resin.


• Avoid cutting thicker sections than the limits given for each type (ultra 150nm, cryo 500nm, histo 2µm).


• Exercise care when picking-up sections. Do not touch the cutting edge with any solid objects (grids, loops, tweezers, etc). • Do not allow the sections dry on the cutting edge.


Sectioning at low temperatures Trimming


For successful cryosectioning of biological and materials research specimens trim ming is imperative. Our diamond trim blades trim 45, trim 20, and trim 90 allow you to quickly and easy fulfill your trimming requirements.


For trimming we recommend the same temperatures as set for the sectioning. For trimming it is advisable to use an ionizer. It eliminates section debris sticking to the specimen and on the trim blade.


Sectioning


For dry cryo sectioning the following temperatures are recommended for the cryo chamber, knife and specimen:


• Sucrose infiltrated biological samples: semithin sections – 80°C, ultrathin sections – 110° to – 120°C


• Frozen hydrated biological samples: – 150°C • Polymers, rubber: – 120°C (or below the glass transition temperature) .


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