Channeling studies

Vitkavage D J, Dale C J, Chu W K, Finstad T G and Mayer T M 1986 Ion channeling studies of low energy ion bombardment induced crystal damage in silicon Nucl. Instrum. Methods B 13 313-18... 

The L-type Ca channels have the richest pharmacology of all Ca channels studied to date. Many different types of drugs have been demonstrated to bind to L-type Ca channels and modify their ability to open [4,14,15]. Most of these drugs block Ca channels and are referred to by many as channel antago-... 

Screening of process conditions was one driver for performing polyethylene synthesis [1]. Thus, test-throughput frequency, the number of possible samples per day, is a target value. Also, flexibility with regard to temperature and pressure at low sample consumption is a major issue. In addition to fastness and flexibility, the quality of the information and the insight obtained is seen as a motivation for micro-channel studies. 

Martin, R.J., Robertson, A.P., Bjorn, H. and Sangster, N.C. (1997) Heterogeneous levamisole receptors a single-channels study of nictotinic acetylcholine receptors from Oesophagostomum dentatum. European Journal of Pharmacology 322, 249-257. 

Fig. 8. SIMS profiles of 2H and nB in plasma-passivated B-implanted and annealed samples used in channeling studies of B—H complexes by Marwick et al. (1988). 1000 angstroms was etched off the surface of this sample to eliminate a layer containing a large excess of hydrogen. Nevertheless, some excess over the boron concentration remains at shallow depths. The histogram shows the deuterium profile used to analyze the data using calculated flux profiles.

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... 

Recent channeling studies have been interpreted to indicate H—B pairs with hydrogen distributed between both the BC and Si—AB sites, with a preference for the BC site at low temperatures. (Marwick et al., 1987, 1988 Bech Nielsen et al., 1988). The boron is estimated to be off the substitutional site by roughly 0.2-0.3 A. This is consistent with the PAC measurements of the similar H—In pair, where the Si—AB site is favored at higher temperatures (T > 150 K), but the BC site is favored at lower temperatures (Wichert et al., 1987, 1988 Wichert, 1988). Also from the PAC studies, the H—In defect is found to anneal with a dissociation barrier estimated to be about 1.3 eV (Wichert et al., 1987). 

ZhuGe R, Fogarty KE, Tuft RA, Lifshitz LM, Sayar K, Walsh JV 2000 Dynamics of signaling between Ca2+ sparks and Ca2+-activated K+ channels studied with a novel image-based method for direct intracellular measurement of ryanodine receptor Ca2+ current. J Gen... 

Peng F, Mellor IR, Williamson MS, Davies TG, Field LM, Usherwood PN (2009) Single channel study of deltamethrin interactions with wild-type and mutated rat Nav1.2 sodium channels expressed in Xenopus oocytes. Neurotoxicology 30 358-367... 

Channeling studies of impurity-defect interactions in Si show that under helium ion bombardment the trapping efficiency of impurities for radiation-produced defects is very low, near 30 K (19). Vacancies are not mobile in Si below this temperature, whereas interstitials still are. This observation implies that the impurity-defect interactions involve vacancies. 

Franco-Obregon and Lansman, 1994) several other properties are also different, including increased activity with depolarization in Lansman (and other studies of canonical MS channels) but decreased activity with depolarization in Vandebrouck. Finally, McBride and Hamill (1992) observed stretch-activated channels with no clear evidence for stretch-inactivated channels in dystrophic muscle, although the number of channels studied might not have been sufficient to observe such channels. 

Igarashi, A. and Toshima, N. (1994). Hyperspherical coupled-channel study of positronium formation. Phys. Rev. A 50 232-239. 

It is possible that the water-filled a-LTX channel, which is relatively wide ( 10A at its narrowest (Krasilnikov and Sabirov 1992 Orlova et al. 2000), can pass small molecules. Indeed, a-LTX channels inserted in the membranes of synaptosomes, NMJ nerve terminals, and receptor-transfected COS7 cells appear to pass fluorescein (Stokes-Einstein radius, Re = 4.5 A) and norepinephrine (Re < 4 A) (Davletov et al. 1998 Rahman et al. 1999 Volynski et al. 2000), shown in Figure 2 for comparison with 8-hydrated calcium ion (Rc = 4.2 A) and the toxin channel. Analysis of impermeant cations commonly used in channel studies reveals that a-LTX channels are poorly permeable (Hurlbut et al. 1994) to glucosamine H+(Re = 4.6 A) and not significantly permeable (Tse and Tse 1999) to N-methyl-D-glucamine (Re = 5.2 A), thus limiting the pore diameter by 10 A. 

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