Object slide

The coefficient of friction between two unlubricated solids is generally in the range of 0.5-1.0, and it has therefore been a matter of considerable interest that very low values, around 0.03, pertain to objects sliding on ice or snow. The first explanation, proposed by Reynolds in 1901, was that the local pressure caused melting, so that a thin film of water was present. Qualitatively, this explanation is supported by the observation that the coefficient of friction rises rapidly as the remperarure falls, especially below about -10°C, if the sliding speed is small. Moreover, there is little doubt that formation of a water film is actually involved [3,4]. 

For macroscopic objects the adhesion force is often small compared to the load. For microscopic bodies this can be different. The reason is simple the weight of an object sliding over a surface usually decreases with the third power of its diameter (or another length characterizing its size). The decrease of the actual contact area and hence the adhesion force follows a weaker dependence. For this reason, friction between microbodies is often dominated by adhesion while in the macroscopic world we can often neglect adhesion. 

Never lift the slide from the stage, but, after raising the objective, slide it off the stage without upward movement. 

The classical laws of friction were noted in the works of da Vinci [69, 70], Amontons [71], Coulomb [72], and Euler [73]. In simplest terms friction is the resistance to motion which occurs whenever an object slides across another surface. The laws of sliding friction may be summarized as ... 

An object sliding on a solid surface experiences a frictional force that is constant and in the opposite direction to the velocity if the particle is moving, and is zero it is not moving. Find the position of the particle as a function of time if it moves only in the x direction and the initial position is x(0) = 0 and the initial velocity is U c(0) = i>o = constant. Proceed as though the constant force were present at all times and then cut the solution off at the point at which the velocity vanishes. That is, just say that the particle is fixed after this time. 

To keep an object sliding at a constant speed over a flat surface, one needs to apply a force that is equal to the friction force F, which acts parallel to the surface, in... 

The results presented in this paper were achieved by a system where every analyzed particle resting on an object slide, was definitely oriented by special holders and viewed under a microscope. Fig. 1 shows in principle the utilized coordinate system in relation to a system aligned to the object slide. The particle can be imagined to rest in the origin of a three dimensional, Cartesian coordinate system, oriented in the depicted manner. The angle a has a value of approximately 27°. 

Carefully wash an object slide with water and then 70 % ethanol and let it dry. Cut a reinforcement ring into two halves, and stick them some distance apart onto the object slide wearing gloves as shown in Fig. la. The reinforcement ring acts as a spacer that... 

Fig.1 Useful tools for dissection and immunostaining. (a) Conventional reinforcement rings are glued to an object slide or coverslip and serve as cheap and easy-to-use spacers to prevent the tissue from squeezing by the coverslip. (b) A custom-sharpened Dumont 5 forceps. The rather fhick shanks and the rather blunt tip prevent easy deformation, give stability when holding small tissues, and allow re-sharpening the tip easily. Note the tight grip at the tip. (c) Petri dishes of different diameters filled with a silicon polymer without left) and with rightj added charcoal, (d) Mesh baskets can be made from cut plastic tubes of appropriate size which are closed on one side with fine nylon mesh (e.g., as used for offset-printing see insert) and are useful to wash tissue or vibratome sections in a well plate...

Alternatively it is possible to use two coverslips separated by a reinforcement ring as spacer instead of an object slide plus cover-slip, as this method allows scanning from both sides. This might be necessary especially for the adult brain if too much IF signal intensity is lost when scanning the deeper parts that are further away from the objective see A). 

Transfer the preparations with a pipette to an object slide or coverslip with spacer see Sect. 2.2.2). Slowly remove the PBS and add 80 % glycerol to cover the tissue see Note 19). Let stand for 1 min, and then remove the glycerol carefully, not to get rid of the now transparent preparations. Add 60 pL 80 % glycerol, and add a coverslip. Make sure that the glycerol will not reach the reinforcement ring as it would suck up the specimen. Then seal the coverslip with nail polish see Note 20). Such specimens can be stored in darkness at 4 °C up to several months. 

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