Substrate rotation

Do appreciate that one enzyme will not catalyse all three types of reaction. We need different enzymes to accomplish a particular reaction on a particular substrate. Rotation about the N-C bond positions the vulnerable group for reaction it also positions the R and/or C02 groups so that they can interact and bind to the enzyme, thus providing the specificity. 

In VTE arrival of the individual molecules can be described as ballistic transport, thus the mfp is comparable with the crucible-substrate distance. Consequently the symmetry of the crucible, for example point source, multiple point source or linear source, and the texture of the organic materials loaded, is reflected in the thickness uniformity and layer coverage of the substrate. This explains the shadowing effects observed for structured substrates [12, 40, 44], As a result, coverage of the substrate by VTE is less uniform and may lead to pin-holes and is obviously not as perfect or quantitative as in OVPD. To reduce this disadvantage in VTE and to improve layer uniformity and coverage VTE uses, for example, substrate rotation to randomize the ballistic trajectories. 

A similar technology has also been reported by Maniv et al. [82] using RF biased substrate rotation and larger magnetrons. The lowest resistivity... 

Provide uniform films because of planetary substrate rotation. The rotation tends to smooth out substrate temperature differences and gas flow differences near the substrate surface. 

The physics of the substrate rotation after the solution is dispensed leads to a fluid flow condition where the rotational accelerations are exactly balanced by the viscous drag felt within the solution at each stratum level. This flow condition was first described by Emslie, Bonner, and Peck (hereafter referred to as EBP) and their article has been the foundation for many more recent studies. For most solutions, another important balance is established between viscous outward radial flow of the solution on the surface of the substrate and the evaporation of... 

All the fabrication steps were performed in a dust-free environment and under dim red light. The SC film of all-rra 5-/3-carotene was prepared using a spin-coating apparatus fabricated by us. An aliquot (about 20 /u]) ofa chloroform solution of a ]-trans /3-carotene (0.02 M) was spread onto the glass substrate rotating at 2500 rpm, and the solvent was evaporated in air. The film thus fabricated was immediately subjected to optical measurements. 

Two instances of micron-scale resolution patterning are illustrated by the SEMs in Figure 2.22 (a) Alqj patterns deposited on Si by VTE through Ni meshes at Ppatterns deposited by OVPD at P ep = 2 torr. The vacuum-deposited patterns show the trapezoidal profile discussed in Section 2.5 where p < 1pm, while OVPD patterns have edge dispersion in the order of 1-3 pm. Simulations in... 

Figure 1.15 SEM images of lri2Se3 deposits on thin Cu-coated Mo substrates rotated at (a) 250 and (b) 0 rpm.

Figure 4.18 Results of electrodeposition of sensitized ZnO on ELITEX conductive textiles, (a) Current density during electrodeposition at 70°C from a resting oxygen-saturated aqueous 0.1 M ZnCl2 solution with 50pM eosinY (squares averaged by the dashed line) compared to the current density observed at a planar substrate rotating at 500 rpm under otherwise identical conditions (solid line).

In centrifugal microfluidic systems, the Navier-Stokes equation is most conveniently expressed within the reference frame where the substrate rotating at a frequency m = 2nv... 

Colloidal solution for preparation of tin dioxide films was deposited on glass substrate. Rotational speed of the centrifuge was 3800 rpm. Centrifugation time was 3-5 s. The substrates with the deposited films were dried by an infrared emitter at 80 C for 3-5 min. Low temperature annealing was maintained to prevent the occurrence of cracks on the Sn02 films. Then the sample is placed in a muffle furnace and dried at 400 C for 15 min. The number of deposited layers of Sn02 was 15. The thickness of the deposited film was estimated from the weight of the film and was about 300 nm. 

Figures 5(a) shows a schematic of the experimental setup for the flipping rotation mode in oblique angle sputter deposition. The rotational axis is in the substrate plane and parallel to the substrate plane. The rotational axis is also perpendicular to the incident flux direction. This means the angle between the axis of rotation and the direction of incident flux on the substrate is fixed at 90° The curved arrow represents the rotation direction. Therefore, the incident flux angle a(t) changes as the substrate rotates in a flipping mode. This is in contrast to the conventional setup shown in Fig. 5(b) where the axis of rotation is perpendicular to the substrate plane and the flux incident angle is fixed as the substrate rotates. Two samples can be placed on each side of the substrate holder in the flipping rotation mode whereas only one sample can be placed on the substrate holder in the conventional rotation mode.

In centrifugal microfluidic systems, the Navier-Stokes equation is most conveniently expressed within the reference frame where the substrate rotating at a frequency = 27ri> is at rest (Fig. 1). Due to the non-inertial nature of this frame of reference, the centrifugal force density the Euler force density and the Coriolis force density/c additionally appear in the hydrodynamic equation... 

One could have impression that the centrifugal force and/or viscous drag against it would be the key for the evolution of radiative striations. And, substrate rotation is believed to be needed for formation of radiative striations. However, we have found that striations are formed even when the substrate is stationary, not rotated (Kozuka, 2002c, 2003c). 

On the basis of the experimental facts described in In situ Observation of Striations in Gel Layers Deposited on Stationary Substrates one can assume that the origin of Striations is the same whether the substrate rotation is present or not. Therefore, in situ observation of gel layers deposited on stationary substrates could provide some information. A drop of a titania sol was dispensed on a stationary substrate, and in situ observation was made... 

Spin coating This involves subjecting a drop of the polymer solution taken onto a substrate to high-speed rotation. Drying and atmealing of the films at elevated temperature may also be needed. The film thickness, which is more uniform than in the dropping technique, can be adjusted by changing the solution concentration and the speed of substrate rotation. 

Figure 1. Ultrasonic humidifier-horizontal reactor setup (1) substrate (2) substrate rotation motor (3) furnace (4) spray nozzle (5) carrier gas (6) solution (7) membrane (8) ultrasonic humidifier.

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