Filament plasma

Jung, K., Boo, 1., Hong, B. - Synthesis of carbon nanotuhes grown by hot filament plasma enhanced chemical vapor deposition method . Diamond Related Mater. 13 (2004) 299-304... 

Another surface functionalization enhancement created by thin film deposition pertains to the wickability. Textile wickability depends primarily on the capillary effect along and between textile fibers. This property is leveraged today with apparel which rapidly transports sweat from the body. Atmospheric pressure plasma polymerization can increase the hydrophilicity at the fiber surface. Critical to this purpose is the sufficient diffusion of precursor-rich plasma species between and around the filaments. Plasma parameters such as power density and gas/pre-cursor introduction rate will influence the efficiency of the surface activation and deposition. Ultimately, there is an optimal power density and precursor introduction rate which will meet the practical processing requirements of the textile. Likewise, penetration of the active plasma/precursor species will be dependent... 

T.R. Gilbert and K.J. Hildebrand. A graphite filament plasma/echelle spectrometer system. Amer. Lab., 72 (February, 1982). 

Fundamentally, introduction of a gaseous sample is the easiest option for ICP/MS because all of the sample can be passed efficiently along the inlet tube and into the center of the flame. Unfortunately, gases are mainly confined to low-molecular-mass compounds, and many of the samples that need to be examined cannot be vaporized easily. Nevertheless, there are some key analyses that are carried out in this fashion the major one i.s the generation of volatile hydrides. Other methods for volatiles are discussed below. An important method of analysis uses lasers to vaporize nonvolatile samples such as bone or ceramics. With a laser, ablated (vaporized) sample material is swept into the plasma flame before it can condense out again. Similarly, electrically heated filaments or ovens are also used to volatilize solids, the vapor of which is then swept by argon makeup gas into the plasma torch. However, for convenience, the methods of introducing solid samples are discussed fully in Part C (Chapter 17). 

Greater sensitivity is attained if an additional ionization mode is included. This can be in the form of a radioactive source, a heated filament, or a plasma or glow discharge. 

Hot RF and - DC plasma, are discharge, plasma jets Oxy-acetylene flames Low pressure microwave plasma, holt filament. Low pressure DC or RF glow discharge Thermal decomposition... 

Electrothermal vaporization can be used for 5-100 )iL sample solution volumes or for small amounts of some solids. A graphite furnace similar to those used for graphite-furnace atomic absorption spectrometry can be used to vaporize the sample. Other devices including boats, ribbons, rods, and filaments, also can be used. The chosen device is heated in a series of steps to temperatures as high as 3000 K to produce a dry vapor and an aerosol, which are transported into the center of the plasma. A transient signal is produced due to matrix and element-dependent volatilization, so the detection system must be capable of time resolution better than 0.25 s. Concentration detection limits are typically 1-2 orders of magnitude better than those obtained via nebulization. Mass detection limits are typically in the range of tens of pg to ng, with a precision of 10% to 15%. 

A large number of CVD diamond deposition technologies have emerged these can be broadly classified as thermal methods (e.g., hot filament methods) and plasma methods (direct current, radio frequency, and microwave) [79]. Film deposition rates range from less than 0.1 pm-h to 1 mm-h depending upon the method used. The following are essential features of all methods. 

MTs extend from the centrosome throughout the cytoplasm to the plasma membrane, where they are stabilized by caps. Sliding along the MTs, kinesin and dynein motors transport their cargoes between the center and the periphery of the cell. MTs present in the axons of neur ons are extended not only by addition of heterodimers to the plus ends but also by use of short MTs that initiate in the centrosome. Their axonal transport is mediated by dynein motors that are passively moved along actin filaments. Once formed in the axon, MTs serve as tracks for the fast axonal transport, i.e. the movement of membranous organelles and membrane proteins to the nerve ending. 

Fibrin is an elastic filamentous protein elaborated from its precursor, fibrinogen, which is present in plasma at high concentration. Fibrin is formed in response to the actions of thrombin. Thrombin cleaves small peptides from the fibrinogen molecule, forming fibrin monomers that will begin to polymerize and become crosslinked. 

Like synthetic diamond, C-BN is normally obtained by high-pressure processing. Efforts to synthesize it by CVD at low pressure are promising. It is deposited in an electron-cyclotron-resonance (ECR) plasma from a mixture of BF3 and either ammonia or nitrogen at 675°C on an experimental basis.F l Like CVD diamond, it is also deposited by the hot-filament method using diborane and ammonia diluted with hydrogen at 800°C.P 1... 

More than 50 proteins have been discovered in the cytosol of nonmuscle cells that bind to actin and affect the assembly and disassembly of actin filaments or the cross-linking of actin filaments with each other, with other filamentous components of the cytoskeleton, or with the plasma membrane. Collectively, these are known as actin-binding proteins (ABPs). Their mechanisms of actions are complex and are subject to regulation by specific binding affinities to actin and other molecules, cooperation or competition with other ABPs, local changes in the concentrations of ions in the cytosol, and physical forces (Way and Weeds, 1990). Classifications of ABPs have been proposed that are based on their site of binding to actin and on their molecular structure and function (Pollard and Cooper, 1986 Herrmann, 1989 Pollard et al., 1994). These include the following ... 

Stress fibers are parallel bundles of actin filaments that develop in the cytoplasm of fibroblasts from the cortical actin network in response to mechanical tension. These often bind to the plasma membrane at focal contacts and, through transmembrane linker glycoproteins, to the extracellular matrix. Thus, actin filaments of stress fibers indirectly Join to the inner face of the plasma membrane through molecular assemblies of attachment proteins, which include an actin-capping protein, a-actinin, vinculin, and talin (Small, 1988). 

Bundles of parallel actin filaments with uniform polarity. The microvilli of intestinal epithelial cells (enterocytes) are packed with actin filaments that are attached to the overlying plasma membrane through a complex composed of a 110-kD protein and calmodulin. The actin filaments are attached to each other through fimbrin (68 kD) and villin (95 kD). The actin bundles that emerge out of the roots of microvilli disperse horizontally to form a filamentous complex, the terminal web, in which several cytoskeletal proteins, spectrin (fodrin), myosin, actinin, and tropomyosin are present. Actin in the terminal web also forms a peripheral ring, which is associated with the plasma membrane on the lateral surfaces of the enterocyte (see Figure 5, p. 24). 

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