Hardening plasma

In essence, the basic steps of making cell blocks consist of fixation, centrifugation to make cell pellet, transfer the pellet to a labeled tissue cassette which then is processed and embedded in paraffin. The most challenging component of this technique is the methods to harden the cell pellet so it can be easily picked up from the tube without losing precious material. With only a simple sedimentation technique, the cell pellet is usually small and friable. In order to harden the cell pellet, several technical modifications have been reported. The most popular methodology includes plasma-thrombin clot technique, agar technique, and fixation with Bouin s solution. 

Plasma Impulse Coating Vapor Deposition (PICVD) process, 20 53 Plasma nitriding, 16 205 17 208 Plasma nitrocarburizing, case hardening by, 16 211... 

UV exposure (at k < 300 nm) of the AZ resist prior to plasma etching causes polymer cross-linking (167, 168) or decomposition (169) of the resist photosensitizer near the surface. Thus, a hardened shell or case is formed that permits a higher bake temperature without resist flow and also reduces the etch rate due to plasma exposure. Exposure to inert plasma (e.g., N2) causes similar effects (170), possibly because of ion and electron, as well as UV, bombardment of the resist surface. When F-containing discharges are used, fluorination of the resist surface occurs that strengthens the resist (because of the formation of C-F bonds) and minimizes reactivity (171). 

Many changes in the lipid composition of the plasma membrane have been associated with hardening (Lynch Steponkus, 1987). In rye (cv. Puma) an increase of the total lipid content has been measured during hardening (Cloutier, 1987). Free sterols increased while steryl-glycoside and acylated steryl-glycoside decreased. In addition the phospholipid contents of the plasma membrane increased. 

Important data on the structure of the films were obtained in an analysis of electron diffraction patterns recorded directly in the transmission electron microscope. In all cases, the diffraction patterns had the form of diffuse halos, which indicate that nanoparticles are in the amorphous state [30]. The fact that the nanoparticles are amorphous is in all probability due to the exceedingly fast cooling of nanometer drops after the expansion of the plasma cloud. Estimates of the cooling rate of nanodrops at the instant of their hardening give values of up to 107K/sec. 

In the present chapter, we will review the nature of plasma-enhanced CVD (PECVD) films for a variety of applications. We will look at dielectrics (silicon nitride, silicon dioxide), semiconductors (polysilicon, epi silicon) and metals (refractory metals, refractory metal silicides, aluminum). There are many other important films (i.e., amorphous silicon for solar cells and TiN for tool harden-... 

Wahl [33] describes the production of highly wear resistant sieves in soft annealed plates of chromium steel by punching, plasma cutting or mechanical working followed by heating and strain hardening. 

Determination of the temperature distribution induced by laser, electron, or plasma beam sources is relevant in operations such as surface transformation hardening of metals, drilling, cutting, annealing, shaping, and micromachining. Descriptions of beam-generating devices as well as discussions of applications are available [7-15]. 

Fig. 3.7. Laser pyrolysis. 1 = Pulsed laser beam ( laser impacf) 2 = pyrolysis 3 = initiation of plasma 4 = thermal hardening 5 = hardening of plasma 6 = thermal desorption and transport of products 7 = laser beam intensity 8 = plasma torch formation (change in height). From ref. 86.

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