Key-lock mechanism

The strong decrease in catalytic activity is not in line with the moderate increase of overall Si/Al ratio determined with A1 MAS NMR (Tablel). The activity of the overgrown MTT t3ipe zeolites rather reflects the aluminum content on the surface of the crystals such as determined by XPS on the 75/25 sample. The 75/25 sample wi its surface Si/Al ratio of 244 is ca. 10 times less active than core material having a surface Si/Al ratio of 38. The synthesized MTT tj e zeolites become less active in hydroisomerization with increasing shell thickness. This is a logical evolution since the acid sites necessary for pore mouth and key lock mechanisms are to be located on the zeolites surface [14]. 

Just thread the wire through the lock, tighten the key locking mechanism and snap it off. 

Sorbent offers specially formed adsorphon sites provided for example by organic molecules impregnating an activated carbon. These anchor molecules only accept (biochemical) admolecules having an appropriate complementary atomic group (key-lock-mechanism). 

The key and lock mechanism is widely accepted as a principle of molecular recognition. This concept is based on steric and electronic complementarity between... 

Latch- A beveled metal tongue operated by a spring-loaded knob or lever. The tongue s bevel lets you close the door and engage the locking mechanism, if any, without using a key. Contrasts with dead bolt. 

Figure T.S. (a) Key and lock mechanism cannot operate at the molecular level because (b) the key adheres to the lock prematurely.

The use of plastics in steering wheels is discussed in Chapter 4. In steering mechanisms plastics have a key role. Nylon is widely used for the housings of the lock mechanism at the top of the steering column, and for the stone... 

Fig. 2. Principle mechanisms of formation of a receptor—substrate complex (a) Fischer s rigid "lock-and-key" model (b) "induced fit" model showing...

Affinity Chromatography. This technique involves the use of a bioselective stationary phase placed in contact with the material to be purified, the ligate. Because of its rather selective interaction, sometimes called a lock-and-key mechanism, this method is more selective than other lc systems based on differential solubiHty. Affinity chromatography is sometimes called bioselective adsorption. 

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