Orientation uniform

Fiber orientation uniformity is also affected by small-scale or timewise variations in polymer viscosity, related to breakage of polymer chains during the extrusion process. The degradation occurs as a result of residual moisture that immediately reacts to break chains, and by thermal degradation that occurs more gradually over time. Different residence times and temperature histories within the laminar flow streamlines lead to different viscosities, and hence different average orientation levels in the different fibers. 

Relative scales of the spinning processes for staple and filament products are depicted in Table 12.1. The industrial filament process is intermediate to the staple and textile filament processes, in terms of both spinning throughput and fiber orientation uniformity (here measured by spun birefringence level). Industrial yarns must be uniform enough to be drawn to much higher tenacity levels than staple yams, but are not dyed and therefore not subject to the more demanding uniformity requirements of textile yams. 

Probably the best means of protein attachment is through highly specific affinity interactions (e.g., streptavidin-biotin or His-tag-nickel-chelates) [111]. Proteins fused with a high-affinity tag, at their amino or carboxyl terminus, are finked to the surface of the chip via this tag, and hence all the attached proteins should orient uniformly away from the surface. Using this method, immobilized proteins are more likely to remain in their native conformation, while the analytes have easier access to the active sites of the proteins. 

The experimental device constructed to orient uniformly thick samples in simple shear is schematically represented in Fig. 3. It is basically a sliding-plate rheometer, the polymer sample being sheared between two temperature-controlled parallel plates. The upper plate is fixed whereas the lower plate can be displaced both horizontally and vertically with two pneumatic jacks. 

NEXAFS data analysis to extract orbital orientation follows simple equations that are trigonometric expansions of the cos 5 relationship described in Section 4.1.3. The typical orientation of interest for organic semiconductors is a surface-relative orientation uniformly distributed about the surface normal. In this case, the azimuth-ally averaged tilt of the orbital can be determined. For a vector orbital, the intensity can be expressed as [31]... 

They may, however, point in any direction perpendicular to it. Accordingly, the nematogens with negative diamagnetic anisotropy do not orient uniformly in a magnetic field, but exhibit a lower order with respect to an external axis than the nematic phases with positive anisotropy. Nevertheless, it is possible to obtain high resolution nmr spectra in liquid crystalline solvents of this type [26]. High resolution nmr spectra have also been observed in the nematic soap solution [13]. 

Very recently Meiboom and Luz [6] have shown that smectic liquid crystals of compounds which exhibit a nematic and a smectic phase may be oriented uniformly by a magnetic field in the following way first the nematic phase is oriented in the magnetic field. Then the sample is slowly cooled below the nematic-to-smectic transition while it is kept in the magnetic field. In this way all three smectic phases A, B, C of terephtal-bis-(4-n-butylaniline) can be ordered uniformly. 

In Abbe s double prism method a thin ho-meotropically oriented nematic film is placed between the hypotenuse faces of two rectangular prisms. Using light polarized parallel and perpendicular to the optical axis, respectively, the principal refractive indices and can be obtained directly from the critical angle of total reflection, provided that the refractive index of the prism is greater than that of the liquid crystal [2, 8-10]. In some cases the director of the nematic phase was oriented uniformly parallel to the prism planes [11-14]. Special variants of the total reflection method have been described [3, 4, 15, 16]. A total reflection refractometer of the Abbe type has also been used to determine n, n and An in the infrared region between 2.5 and 14 p.m [17]. 

The controllable nanospace of PCPs is a competent candidate for the accurately controlled reaction field. In these micropores, guest molecules are strictly arranged and oriented uniformly, and gas molecules are no exception. Guest molecules and reactants approach each other spatially and react regioselectively through excitation by the external stimuli. After the reaction, the products are released outside of the pores because the pores are not suitable for the size and shape of the products and have no affinity for them. The products of this ideal reaction cycle rely heavily on the shape and size of the nanospace. By choosing the pore structure, different products can be obtained from the same reactants. Moreover, this spatial reaction control may produce unparalleled reaction paths and products that cannot be realized in homogeneous systems. 

The effect of the alignment layer that used surfactant and polyvinyl alcohol is disclosed in the patent by the NCR company, filed in 1972. It was tested carefully in the laboratory, but the most important factors for industrialization, orientation uniformity, stability, and high productivity were still unsolved difficult problems. 

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