Channeled ions

Ion-beam lithography Ion beam mixing Ion beam processing Ion beams Ion-beam sputtering Ion channels Ion chromatogram Ion chromatography... 

Fig. 7. A shows range distributions for channeled ions implanted along the <100> axis of Si. B shows the Gaussian distribution for incident ions aligned...

Each porin molecule has three channels Ion channels combine ion selectivity with high levels of ion conductance The K+ channel is a tetrameric molecule with one ion pore in the interface between the four subunits... 

Experimental data from Bech Nielsen s study is shown in Fig. 6 and Fig. 7. The data show that implanted 2H is found predominantly in bond-center sites. This qualitative conclusion can be drawn immediately from the raw channeling data, especially the 111 planar scans, and does not depend on the details of the model used to subsequently analyze the data in greater detail. Si—Si bonds run perpendicularly across the 111 planar channel. At zero tilt, a strong flux peak of planar channeled ions is focused on the bond centered site and causes the peak seen in the data at this angle. However, back-bonded sites are hidden in the wall of this channel, which is unusually thick and consists of two planes of atoms close together. Thus, the ion flux near the back-bonded sites is low when the tilt angle is small, hence the dip in nuclear reaction yield calculated for this site. Bech Nielsen (1988) found that this data pointed to there being a minority of the 2H... 

Bech Nielsen et al. (1988) also made a channeling study of the 2H in B-2H complexes that was similar in principle to that just described but differed in details of technique and in some of the conclusions arrived at. Also, they did not investigate the position of the boron atoms. They used Si uniformly doped with a high (1 x 1019 B/cm3) boron concentration, rather than implanted boron. The surface was etched off after hydrogenation, but no SIMS data was presented to confirm the uniform hydrogen concentration assumed. The penetration depth of the H was given as —7000 A. The channeling measurements were performed at 30 K. For analysis of their data Bech Nielsen et al. used the same model, based on the assumption of statistical equilibrium (SE) of the channeled ions, already described in connection with the measurements of implanted deutrium... 

Several types of ion-channeling experiments (see Chapter 9) also give useful information on atomic positions at impurities or impurity complexes. These include both scattering of channeled ions by atoms that disrupt the uniformity of a channel path and the production of nuclear reactions by collision of a channeled ion with an impurity nucleus (e.g., incident 3He colliding with dissolved 2H to give 4He plus a proton, which can be detected). Here again, one can study lattice positions of solute atoms and changes in populations of different sites. 

Nifedipine is a calcium-channel blocker of the dihydropyridine group. It relaxes smooth muscle and dilates both coronary and peripheral arteries by interfering with the inward displacement of calcium-channel ions through the active cell membrane. Unlike verapamil, nifedipine can be given with beta-blockers. Long-acting formulations of nifedipine are preferred in the long-term treatment of hypertension. 

In this chapter, we review the current status of doping of SiC by ion implantation. Section 4.2 examines as-implanted depth profiles with respect to the influence of channeling, ion mass, ion energy, implantation temperature, fluence, flux, and SiC-polytype. Experiments and simulations are compared and the validity of different simulation codes is discussed. Section 4.3 deals with postimplant annealing and reviews different annealing concepts. The influence of diffusion (equilibrium and nonequilibrium) on dopant profiles is discussed, as well as a comprehensive review of defect evolution and electrical activation. Section 4.4 offers conclusions and discusses technology barriers and suggestions for future work. 

Figure 7.2 The cell membrane consists of protein icebergs floating in a sea of Upid. The proteins are a collection of ion channels, ion pumps, and G-proteins. These afford a rich diversity of potential dmg targets.

The cell uses various mechanisms to trigger and regulate the flow of ions through ion channels. Ion flow is subject to the following gating mechanisms, according to the natme of the ion channel ... 

De Waard M, Gumett CA, Campbell KP (1996) Structural and functional diversity of voltage-activated calcium channels. Ion Channels 4 41—87. 

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