Direct polarity machining

An active cathode (direct polarity machining) or active anode (reverse polarity machining) [63] can be used as a tool, of which the use of the former is most popular. As the discharge activity, and especially the discharge mechanism, differs for an active cathode and anode, the machining performances will also be different. 

Paper made on a paper machine exhibits quite different properties in the x and y directions (the machine and cross machine directions), an example of which is a difference in stiffness which can be demonstrated by plotting the specific elastic stiffness in the x-y plane as a function of the machine direction and cross machine direction co-ordinates in the form of a polar diagram (Figure 4.7). 

Fig. 9. Polar diagrams of elongation to break in uniaxially and biaxially stretched films, (a) Uniaxially stretched, free transverse direction, 3.0 x 10 (b) uniaxially stretched, fixed transverse direction, 3.0 x 1.0 and (c), simultaneous, biaxially stretched, transverse direction, 3.0 X 3.0. ND = normal direction, MD = machine direction, and TD = transverse direction. Courtesy of Journal of Applied Polymer Science.

Flexible polyethylene separators have facilitated a novel cell construction the separator material, supplied in roll form, is wound so that it meanders around electrodes of alternating polarity (Fig. 23), requiring ribs in the cross-machine direction such profiles are available commercially [60],... 

Normal incidence transmission IRLD measurements are used to study thin films (typically 100 pm thickness and less, depending on the molar extinction coefficient of the bands) with in-plane uniaxial orientation. Two spectra are recorded sequentially with the radiation polarized parallel (p) and perpendicular (s) to the principal (machine) direction of the sample. The order parameter of the transition moment of the studied vibration is calculated from either the dichroic ratio (R — Ap/As) or the dichroic difference (AA = Ap—As) as ... 

Fig. 10.28. Sequence of snapshots of martensitic microstructnre corresponding to different load levels (courtesy of R. James and C. Chu) as obtained using polarized hght. Different shades correspond to different variants of the Cu-Al-Ni martensite. Biaxial stress state applied using machine shown in fig. 10.27, with stresses applied along (Oil) and (Oil) directions (a) =...

Fig. 14.7. ID static C NMR spectra for a biaxially drawn PET film with its machine direction (MD) parallel to the receiver coil axis. Spectra (a) and (b) were obtained after cross-polarization and a Hahn spin echo. Spectra (c) and (d) were obtained with single-pulse excitation using a 1-s recycle delay, which selects for the most highly mobile segments. Little orientation dependence is observed for the mobile components.

The multivalent phosphates, already significantly limited in hydration, can be expected to reach out substantially further than carboxylates in their search for adequate hydration. This effect becomes enhanced when phosphate access to water is limited. When the phosphate occurs at the base of a cleft, the direction for access of water becomes severely limited and the thirst for hydration can be directed by the cleft to target sites of hydrophobic association. In other words, the cleft functions as a conduit to direct the thirst for hydration. By means of the cleft, the capacity for disrupting hydrophobic hydration to target sites can be boosted by effecting separation of ion pairs enroute, which boost the polar species capacity to disrupt hydrophobic hydration. Accordingly, the use of structure to direct the forces of apolar-polar repulsion becomes a useful design feature in certain ATP-driven protein-based machines, such as the myosin II motor. 

Figure 5.20. Optical micrographs under crossed polars obtained at Tm= 80°C, for PP containing the needle nucleating agent (N,N -dicyclohexyl-2,6-naphthalenedicaiboxamide). MD (machine direction) represents the flow direction and TD denotes the transversal direction. [Adapted, by permission, from Yamaguchi, M Irie, Y Phulkerd, P Hagihara, H Hirayama, S Sasaki, Polymer, 51, 5983-9, 2010.]...

Both the Doppler slice and the ion TOP measurement are essentially in the centre-of-mass system. Therefore the measurement directly maps out the desired 3D centre-of-mass distribution, i.e. d aj v dv dO = I 6,v) v in Cartesian velocity coordinates (d (r/diVx dvy dv ). Thus, the double differential cross-section I 6,v) is obtained by multiplying the measured density distribution in the centre-of-mass velocity space by and then transforming from the Cartesian to the polar coordinate system. This procedure has to be contrasted against the conventional neutral TOP technique (either in the universal machine or by the Rydberg-tagging method), for which the laboratory to centre-of-mass transformation must be performed, or against the 2D ionimaging technique, which involves 2D to 3D back transformation. 

In different experiments film specimens were stretched in the machine direction at constant rate of elongation (85 % strain per minute) at 300 K and 343 K and 10-scan spectra (resolution 4 cm ) were taken in about 11 %-strain intervals with radiation polarized alternately parallel and perpendicular to the direction of stretch and unpolarized radiation. In Fig. 13 the FTIR spectra recorded during elongation at 300 K in the 690-750 cm wavenumber region are shown separately for the parallel and perpendicular polarization directions alongside the corresponding stress-strain diagrams for 300 K and 343 K. The reduction of intermolecular forces in the polymer at elevated temperature is readily reflected by the considerably lower stress level of the 343 K experiment. 

The first extensive SEM investigation of PA6/PET-based MFCs and their precursors performed by Evstatiev et al. [82] undoubtedly showed the fibrillar structure of the PET reinforcements preserved after the PA6 matrix isotropization. Since then, electron microscopy has been used to visualize the orientation and morphology of the matrix and reinforcing components in almost every report on MFCs. It is worth noting some more recent studies on MFCs comprising LDPE and PET as matrix and reinforcement, respectively [30,31]. Several microscopic techniques were used, e.g., SEM, polarizing light microscopy (PLM) and TEM. Thus, by SEM it was demonstrated that the isotropic LDPE matrix embedded PET microfibrils with random orientation. Thin slices of PLM and TEM showed the orientation in the machine direction. The latter method also revealed the formation of transcrystalline layers of LDPE on the oriented PET microfibrils. 

Besides the parameters discussed above, some other factors can also be used to optimize chiral resolution by CE. These parameters include the reversal of polarity, the volume of sample injected, the use of EOF modifiers and pre-derivatization of the chiral pollutants with a suitable reagent. In the normal CE machine, the anode (+) and cathode (—) are always at the inlet and outlet ends, respectively. In this modality, the EOF always tends to travel towards the cathode (detector). On the other hand, in the reverse mode, the direction of the EOF is away from the detector, and hence only negatively charged diastereomeric complexes with an electrophoretic mobility greater than the EOF will pass the detector. This format is typically used with capillaries that are coated with substances that reverse the net charge of the... 

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