Cross arrangement

For interactions between two quadmpolar molecules which have 0 and 0g of the opposite sign, at a fixed separation r, the angular factor in equation (A1.5.13t leads to a linear stmcture, 0 = 0g = 0, being the most attractive. Linear molecules may also prefer a 2 rectangular or non-planar cross arrangement with 0 = 0g = nil, which allows them to approach closer and increase the radial factor. 

X-ray diffraction reveals that the polypeptide chains in the fibrillar assemblies formed by polyAn, polyAi3, and polyA2o are in the cross-// arrangement, that is, where the //-strands run perpendicular to the fiber direction (Fig. 8) (Shinchuk et al, 2005). The X-ray patterns show broad,... 

A cross-// spine structure consists of two or more flat or twisted //-sheets, composed of parallel (Nelson et al., 2005) or antiparallel (Makin et al., 2005) //-strands, in a cross-/ arrangement. The cross-/ spine model of fibril formation proposes that a short segment of the native protein changes conformation to form one or more //-strands of a cross-/ spine. The seven-residue peptide GNNQQNY, derived from the prion-determining domain... 

This idea was realized using crown ether styryl dyes (CESD) lc,d, 4c (Scheme 1,4). The compounds lc,d, 4c having betaine structures form supramolecular dimers with a crossed arrangement of molecules (a h-head-to-tail) in the presence of ions, due to the intermolecular interaction between the sulfo group of one of the molecules and a ion located in the crown-ether cavity of the other molecule [20,21], It was shown that photoirradiation of solutions of dimer results in stereospecific PCA giving only one of the 11 possible derivatives of cyclobutane, which is expected in conformity with the concerted superficial (s,s) addition of the reactants (Scheme 5) [22,23], It is noteworthy... 

Natural organic sorbents — Natural materials such as peat moss, straw, and sawdust that can be used to recover spilled oil. Natural sorbents generally absorb three to six times their weight in oil by virtue of the criss-cross arrangement of fibres within the material. All natural sorbents absorb water as well as oil, however, and may sink when saturated with water. Indiscriminate used of natural sorbents can add to the problems of oil spill cleanup. Synthetic sorbents are usually favoured due to their greater capacity for oil and relative ease of recovery. (See also Mineral-based sorbents, Synthetic organic sorbents.)... 

This sort of cross arrangement has been used by several workers. Peptides were trapped, separated by CE, and detected by ESI-MS using an arrangement as shown in Figure 27.4b. This paper demonstrated the creation of the online SP(M)E in a PDMS chip. Once every 10 s a 1 s injection was made from the back extraction solution. It appeared that the peptides eluted from the SP(M)E... 

FIGURE 27.4 (a) A cross arrangement for online extraction and back extraction with the extraction medium centered in the cross, (b) Reaction medium in one arm. 

Black CuO is made by heating the elements (equation 22.99) or by thermal decomposition of solid Cu(N03)2 or CUCO3 (equation 22.104). Its structure consists of square planar CUO4 units linked by bridging O atoms into chains these lie in a criss-cross arrangement so that each O atom is in a distorted tetrahedral site. Figure 22.29b shows a... 

A fluorescence spectrum shall be measured with a spectral resolution of 10 nm. The experimenter decides to use a crossed arrangement of grating spectrometer (linear dispersion 5 x 10 nm/mm) and an FPI with coatings of / = 0.98 and A = 0.3%. Estimate the optimum combination of spectrometer slit width and FPI plate separation. 

From the figure it is seen that the data for packings with equal hydraulic diamet lie on one and the same line. It must be mentioned also that the packings with cross arrangement of the expanded metal sheets permit about... 

Fig.4.50. Section of the laser-excited Na2 fluorescence spectrum obtained with the crossed arrangement of F.P.I. and spectrograph, shown in Fig.4.49...

The hoUow-fiber membrane is wound into a bundle with a layered, cross arrangement, as shown in Figure 2.4, and moderately sized. Regular intervals arc left between the hollow fibers to minimize pressure differentials and allow uniform flow and achieve small pressure drop. 

Cross array hot wire method (BS EN 993-14 1998 and ISO 8894-1 1987) — In this method, two wires are welded together and sandwiched between the blocks of the test material. One is a heater, and the other is a thermocouple, and they lie in as cross arrangement. Hence the name. Power is fed to the hot wire for a short time, and the temperature rise measured. The temperature rise is related to the thermal conductivity of the material. This arrangement is more suited to measurement of materials with conductivities up to 2 W/mK. 

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