Black-disk model

In the simple black-disk model described above, nuclear effects of the diffuse nuclear surface and the discrete (i.e., quantum) nature of the allowed nuclear structure have been ignored and it is assumed that nuclear matter is perfectly opaque. The optical model addresses these omissions and is the subject of the next major section. One of the major results of this model is the introduction of f-dependent transmission coefficients, T, where 0 < < 1. The... 

Fig. 5 Experimental diffraction pattern. The radii of the right-hand halves of the open circles are proportional to the experimental structure factors, while the left-hand open circles are calculated from the best model (x2=i.2). Black disks Bragg and CTRs reflections.

BB-SFG, we have investigated CO adsorption on smooth polycrystaHine and singlecrystal electrodes that could be considered model surfaces to those apphed in fuel cell research and development. Representative data are shown in Fig. 12.16 the Pt nanoparticles were about 7 nm of Pt black, and were immobilized on a smooth Au disk. The electrolyte was CO-saturated 0.1 M H2SO4, and the potential was scanned from 0.19 V up to 0.64 V at 1 mV/s. The BB-SFG spectra (Fig. 12.16a) at about 2085 cm at 0.19 V correspond to atop CO [Arenz et al., 2005], with a Stark tuning slope of about 24 cm / V (Fig. 12.16b). Note that the Stark slope is lower than that obtained with Pt(l 11) (Fig. 12.9), for reasons to be further investigated. The shoulder near 2120 cm is associated with CO adsorbed on the Au sites [Bhzanac et al., 2004], and the broad background (seen clearly at 0.64 V) is from nomesonant SFG. The data shown in Figs. 12.4, 12.1 la, and 12.16 represent a hnk between smooth and nanostructure catalyst surfaces, and will be of use in our further studies of fuel cell catalysts in the BB-SFG IR perspective. 

The idea of extracting energy from black holes has been proposed by Penrose thirtyhve years ago and followed by a cascade of energy extraction models. Nowadays it is known that from almost all Active Galactic Nuclei (AGNs) which harbour a supermassive (M > 105 x M ) Kerr black hole, focused jets of hot gas shoot into space at relativistic speed. How much energy can these jets get from the black hole or its accretion disk is a question which arises by itself. 

This model contains the idea that particles get to such high energy in the relativistic jets from black holes. The theory [22 23 24] allows us to estimate the maximum particle energy and also the maximum contributed flux. It is used the well tested concept of shock acceleration in the relativistic jet and its shock waves, including the final hot spot, arising from the inner ring of the accretion disk, very close to a rapidly spinning black hole. 

Figure 16 Illustration of DNA origami (A and B) Folding paths of DNA lead and staple strands (lead strand, black staple strand, colored). ((A) Schematic folding and (B) folding with a simple DNA model). (C) Selected possibilities realizable by DNA origami (from left to right (a) disk with three holes ...

Fig. 8 CPK models of (A) p-structural Ala and (B) a-helical Leu derived from PEPCON. The black atoms present carbonyl carbons. A linear and planar solute such as pentacene provides more effective interaction area with the carbonyl groups one-dimensionally-aligned on the rigid main chain than a disk-like solute such as coronene (A). On the other hand, the carbonyl groups of Leu are covered with their bulky residual groups (B).

Fig. 4.13 (A) Crystal structure of bovine rhodopsin viewed from a perspective approximately normal to the membrane. The polypeptide backbone is represented by a ribbon model (gray) and the retinylidine chromophore by a licorice model (black). The coordinates are Irran Protein Data Bank file IfSS.pdb [69]. Some parts of the protein that protrude from the phosopholipid bilayta- of the membrane are omitted fw clarity. (B) The 11-cfr-retinyUdine chromophore is attached to a lysine residue by a protonated Schiff base linkage. Excitation results in isomerization around the 11-12 bond to give an all-rrfl s structure. (C, D) Schematic depictions of a field of rhodopsin molecules in a rod cell disk membrane, viewed nmmal to the membrane. The short arrows in the shaded ovals represent the transition dipoles of individual rhodopsin molecules. (Each disk in a human retina contains approximately 1,000 rhodopsins.) The transition dipoles lie approximately in the plane of the membrane, but have no preferred orientation in this plane. A polarized excitation flash (horizontal double-headed arrow in C) selectively excites molecules that are oriented with their transition dipoles parallel to the polarization axis, causing some of them to isomerize and changing their absorption spectrum (empty ovals in D). (E) Smoothed records of the absorbance changes at 580 run as a function of time, measured with probe light polarized either parallel or perpendicular to the excitation [14]. The vertical arrow indicates the time of the flash. The absorbance change initially depends on the polarization, but this dependence disappears as rhodopsin molecules rotate in the membrane...

Centrifugal partition chromatography (CPC), a type of CCC that uses discrete partition cells inside a rotor, was used by Renault et al. (1997) to separate anthocyanins from black currant and grape skins. They used two instmments from Sanki Engineering Ltd (Kyoto, Japan) a laboratory model LLB-M and a pilot-scale model LLI-7, both fitted with a stacked disks type rotor. 

Fio. 12. Model of the hemoglobin molecule (according to Perutz). One white chain is removed for the sake of clarity. The lines are drawn in to show the course of the peptide chain (usually in the form of the ot-helix). The light disk in the black chain at right represents the porphyrin ring. 

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