Methods crossed filament

Other, similar methods for measuring surface-surface interactions, which come under the generic heading of surface force apparatus, include the crossed-filament method. This utilizes a beam deflection technique similar to that now being used in some AFMs for the measurement of surface displacement [94]. Another technique for displacement measurement used in a similar SFA is that of a capacitance transducer. Both techniques suffer the criticism that separation is not measured at the point of interest, i.e., the gap between the two surfaces as measured in the FECO technique. 

Fig. 11.18. Apparatus for measuring forces of adhesion by the crossed-filament method. 1,2) Platinum filaments 300 i in diameter 3) mirror 4) torsion suspension 5) vessel.

In order to study the adhesion of particles in liquid media, particularly in solutions of electrol5d es and surface-active materials, methods, involving crossed filaments and plane-parallel discs, are often used. 

Malkina and Deryagin [86] used their own method of crossed filaments for equilibrium adhesion in water to obtain a value of A = 1.3 10 erg. However, this value of A cannot be regarded as sufficiently accurate, since the width of the gap separating the contiguous bodies was not measured, but rather assumed to be of the order of 10 cm. The value of A may be determined from Eqs, (1.28) and (1.34). 

In electrolyte solutions (LiCl, NaCl, KCl) adhesion also increases with rising temperature (from 20 to 60°C) this was shown in [46] by the plane-parallel—disc method. A rise in adhesion with increasing temperature was also observed by the crossed-filament... 

Tire Ya.rns, A method to iacrease the strength of viscose yam from the 0.2 N /tex (2.2 gf/den) standard to levels needed ia tires was first patented by Courtaulds ia 1935 (18). By raising the ziac concentration ia the spia bath to 4% the thread could be stretched more by immersing it ia a hot dilute acid bath duting extension. Filament strengths iacreased to about 0.3 N/tex (3.3 gf/den), and the cross section became rounder, with a thicker skin than regular viscose. Pairs of these yams were capable of beiag twisted iato tire cords which outperformed traditional cotton cords. 

To differentiate a filament from a vortex intrusion case, we use a method based on the evolution of the potential vorticity along the cross-section between the OHP station and the vortex center defined from the PV maximum. 

In contrast to the use of large Sf ratios, where attention is focussed on the wall of the tube, Wood and Wise [62, 63] have used short tubes to determine j for the material simulating the end plate. They investigated the recombination efficiency of several metals for H atoms. In the later study [63], their terminal probe was in the form of a heated spiral filament of the metal under investigation. The decrease in energy necessary to maintain the filament at constant temperature was measured and assumed to be proportional to the atom concentration at the cross-section occupied by the filament. The method is preferable to the use of thermocouple probes, whose change in temperature might affect the atom decay profiles. Wood and Wise attribute differences in their results obtained... 

Figure 2.9 Overview of sample introduction methods and hyphenated techniques used in ICP-AES. (A) Pneumatic concentric (sometimes called the Meinhard nebuliser) (B) Babington (C) fritted disc (D) Hildebrand nebuliser (E) cross flow (G) standard ultrasonic nebuliser for aqueous and non-aqueous solvents (H) electro-thermal graphite ( ) electro-thermal carbon cup (K) graphite tip filament (L) laser ablation (M) hydride generation (P) flow injection...

Cut or ground cross-sections of fibres, yams and fabrics are of interest for fibre identification, in fault analysis in primary and secondary spinning and in checking the penetration of dyes into fibres, filaments, yams and fabrics. These methods are also used to investigate hollow and multicomponent fibres, the build-up, adhesion and evenness of coating layers and the analysis of other textile composites. AU of this can be useful for damage analysis. Grieve has written a review on cross-section preparation methods for fibres. 

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