Chain shape, controlling

How Shape Controls Function The Single Chain (3 Phase. 300... 

On the scientific side, considerable progress has been made on two fronts learning how the catalysts operate to make stereoregular polymers and learning how the properties of the polymers are controlled by chain shape, chain length, and, particularly, crystal habit. 

The ability of long alkyl chain amines to induce a shape control of ruthenium nanostructures from ruthenium complexes has been explored by other groups and significant advances have recently been described. Different protocols in organic medium leading to monodisperse nanoparticles such as stars, urchins, and hourglass, from Ru(acac)2 [71] and Ru3(CO)i2 [72], have been reported. These syntheses require the presence of an amine or a mixture of an amine plus a carboxylic acid which play a crucial role in controlling the shape of ruthenium nanocrystals... 

The general concept of the optimal dynamic discrimination (ODD) has been recently proposed by Rabitz and Wolf et al. [60,61]. The idea of the ODD relies on a theoretical analysis which has shown that quantum systems differing even infinitesimally may be distinguished by means of their dynamics when a suitably shaped ultrafast control field is applied. In the case of the two similar flavins (differing only by replacement of H by PO(OH)2 in the side chain) the controlled depletion of the fluorescence signal has been used as a discriminating observable... 

The living polymerization process offers enormous flexibiUty in the design of polymers (40). It is possible to control terminal functional groups, pendant groups, monomer sequencing along the main chain (including the order of addition and blockiness), steric stmcture, and spatial shape. 

After the wood particles are coated with resia, the particles are uniformly distributed iato a board by an air laid process. The art of the process is ia controlling and getting a uniform distribution of the wood particles by blowiag them out onto a collection chain. After forming the board shape it is moved to hot presses where the wood particles are consoHdated and the resia cured. From the hot presses the boards move to trim saws where the boards are cut square to their fiaal size. Ia some cases, the boards are sanded to final thickness and surface smoothness. 

CP-1 was assembled in an approximately spherical shape with the purest graphite in the center. About 6 tons of luanium metal fuel was used, in addition to approximately 40.5 tons of uranium oxide fuel. The lowest point of the reactor rested on the floor and the periphery was supported on a wooden structure. The whole pile was surrounded by a tent of mbberized balloon fabric so that neutron absorbing air could be evacuated. About 75 layers of 10.48-cm (4.125-in.) graphite bricks would have been required to complete the 790-cm diameter sphere. However, criticality was achieved at layer 56 without the need to evacuate the air, and assembly was discontinued at layer 57. The core then had an ellipsoidal cross section, with a polar radius of 209 cm and an equatorial radius of309 cm [20]. CP-1 was operated at low power (0.5 W) for several days. Fortuitously, it was found that the nuclear chain reaction could be controlled with cadmium strips which were inserted into the reactor to absorb neutrons and hence reduce the value of k to considerably less than 1. The pile was then disassembled and rebuilt at what is now the site of Argonne National Laboratory, U.S.A, with a concrete biological shield. Designated CP-2, the pile eventually reached a power level of 100 kW [22]. 

The secondary structure of a protein is the shape adopted by the polypeptide chain—in particular, how it coils or forms sheets. The order of the amino acids in the chain controls the secondary structure, because their intermolecular forces hold the chains together. The most common secondary structure in animal proteins is the a helix, a helical conformation of a polypeptide chain held in place by hydrogen bonds between residues (Fig. 19.19). One alternative secondary structure is the P sheet, which is characteristic of the protein that we know as silk. In silk, protein... 

Amino acids, the building blocks of giant protein molecules have a carboxyl group and an amino group attached to the same carbon atom. A protein is a linear polymer of amino acids combined by pepfide linkages. Twenfy different amino acids are common in proteins. Their side chains, which have a variety of chemical properties, control the shapes and functions of proteins. Some of these side chains are hydrophobic, others are hydrophilic, and still others occur either on the surface or the interiors of proteins. 

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