ULTRA SONIC

 

Dear customer,

 For many years Diatome diamond knives    have been used successfully for a wide range of room- and low temperature sectioning applications.

Major advances in immunocytochemistry, the sectioning of frozen hydrated specimens, semithin sectioning for optical microscopy, as well as the sectioning of hard industrial samples have been realised using Diatome diamond knives


The development of the Static Line II ionizer enabled dry ultramicrotomy of Lowicryls and a considerable improvement in cryosectioning

Despite these innovations, until now, one major obstacle remained, preventing us from achieving perfect ultrathin sections: „compression” (we define compression as the shortening of the section compared to the sample height).

The amount of compression depends on various factors including:

The wedge angle of the knife.

The hardness of the sample.

The interaction diamond surface / section surface.

The section thickness.
The most critical factor is the wedge angle of the knife. It was shown that reducing the wedge angle results in a reduction of compression, hence better preservation of ultrastructure which allows a higher achievable resolution.

However, the wedge angle may not be reduced ad infinitum. A further reduction results in a lower cutting edge quality and a considerably shorter life span.

In cryo-ultramicrotomy, compression, expressed as a percentage, was found almost equal to the wedge angle in degrees:

45° knife 40-50%

35° knife 30-40%.
An oscillating knife for low temperature applications is in preparation.


The oscillating
diamond knife,
exclusively from Diatome!

diatome sonic (17k)
  • Thinner sections
  • No compression
  • Better structural preservation


    Pat. Pending





  • In room temperature ultramicrotomy, we have found the following compression factors (section thickess 50nm):

    10-20% for Epon, Araldite, EM-Bed,
    and other epoxi resins.

    12-24% for Lowicryl K4M.

    10-17% for Spurr’s (hard grade).

    8-13% for LR White (hard grade).
    These limitations have stimulated our efforts to develop the oscillating knife.

    It has been shown that compression in frozen-hydrated sections is the limiting factor for successful electron tomographic analysis (Ref 10, 11). Cryo sections from vitrified samples without compression were achieved by A. Al-Amoudi, LAU, University of Lausanne (Ref 12).
     
     
    Here we proudly

    introduce the DiATOME ultra sonic, the oscillating diamond knife for room temperature ultramicrotomy. It was developed in collaboration with Dr Daniel Studer, Lab. of Anatomy, University of Berne.

    A piezo actuator produces an oscillation of the knife at a desired frequency and amplitude, parallel with the cutting edge. A depression in the foot of the knife allows the oscillation parallel to the cutting edge. The depression is rigid in the north/south direction and guarantees stability in the cutting direction.

    The new knife produces ultrathin sections almost free of compression.

    The sections become thinner at the same thickness setting: since the volume of the section remains the same, the increased length leads to a decrease in thickness.

    The theoretical considerations and first results of this invention were presented in the Journal of Microscopy (Ref 13)

    Results with polymers using the oscillating knife were shown at the M&M 2002 meeting in Quebec (Ref 14).

    We have tested the oscillating knife with the following samples:

    Biological samples in Epon, Araldite,
    EM Bed, etc.

    Biological samples in acrylic resins
    (Lowicryls, LR White).

    Rigid polymers such as PS, PMMA,
    ABS, HIPS, modified PP, etc.


     
    Peripheral nerv (rat).
     
    Heart (rat).


    Human keratinocyte.

     
    ABS.


    Impact modified PP

       
     
    Ordering Literature
     
     
    Specifications.

    Knife

    Knife angle: 35º

    Cutting range: 10-80nm

    Cutting edge length: 3.0mm

    Order number: DUS3530


    Control unit

    Frequency: 25-45kHz, or automatic
    setting of the resonance

    Amplitude: variable (Voltage 0-30V)

    Mains voltage: 230V, 110V

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