Gradient generator

Figure 7.22 The principle of creating a two-dimensional NMR image. A number of profiles of the sample are obtained in different orientations in the presence of magnetic field gradients pointing in different directions (designated by arrows). The x -gradient yields an x -profile, and a /gradient generates a y -profile. A combination of these profiles produces a two-dimensional image.

Abott et al. demonstrated that the flow in a microfluidic channel can be controlled by using the wetting gradient generated by electrochemical reactions ofthe surfactant... 

Fig. 5. Pulse sequence for MR detection of vibration using a radiofrequency field gradient. A binomial 1331 radiofrequency pulse (pulse length D, interpulse delay r) is applied in-phase with the mechanical wave. Thus the vibration period 7V is equal to 4(D + r). The number of cycles can be increased to ensure a better frequency selectivity. The constant RF field gradient generated by a dedicated RF coil allows space encoding without using conventional static field gradients (from Ref. 16 with permission from Elsevier).

This expression applies to the case where there is no mean scalar gradient. Adding a uniform mean scalar gradient generates an additional source term on the right-hand side involving the scalar-flux energy spectrum. 

Collecting duct The duct has selective permeability to water, which is controlled by ADH. In the presence of ADH, water moves into the interstitium down the concentration gradient generated by the loop of Henle. 

Cappiello, A., Eamiglini, G., Eiorucci, C., Mangani, R, Palma, P, and Siviero, A., Variable-gradient generator for micro- and nano-HPLC, Analytical Chemistry 75(5), 1173-1179, 2003. 

Le Bihan, T., Pinto, D., and Eigeys, D., Nanoflow gradient generator coupled with mu-LC-ESI-MS/MS for protein identification. Analytical Chemistry 73(6), 1307-1315, 2001. 

Deguchi, K., Ito, S., Yoshioka, S., Ogata, I., and Takeda, A., Nanoflow gradient generator for capillary high-performance liquid chromatography, Awa/yficaZ Chemistry 16(5), 1524—1528, 2004. 

We also describe the spreading of a thin surfactant laden aqueous film on a hydrophilic solid, i.e., one in which the dynamic contact angle is small. In such a case, the osmotic pressure gradient generated by the nonuniform distribution of surfactant micelles in the liquid film can drive fhe spreading process. The mofivation for this study comes from the need to understand the detergent action involved in the removal of an oily soil from a soiled surface. This paper presents an overview of our recent work. 

---