Folded plate structures

There are different techniques that have been used for over a century to increase the modulus of elasticity of plastics. Orientation or the use of fillers and/or reinforcements such as RPs can modify the plastic. There is also the popular and extensively used approach of using geometrical design shapes that makes the best use of materials to improve stiffness even though it has a low modulus. Structural shapes that are applicable to all materials include shells, sandwich structures, and folded plate structures (Fig. 3-8). These widely used shapes employed include other shapes such as dimple sheet surfaces. They improve the flexural stiffness in one or more directions. 

The methods of analysis and design presented for beams can be applied to the more-complex products such as folded plate structures, which range from bottles to roofing to... 

In the previous chapters we covered the use of material modification such as orientation and the use of fillers to increase the modulus of elasticity of plastics. This chapter is concerned with geometrical design which makes the best use of materials to improve stiffness. Structural shapes which are applicable to all materials are discussed such as sandwich structures, shells, and folded plate structures. In the case of plastics, emphasis is on the way plastics can be used in these structures and why they are preferred over other materials. In many cases plastics can lend themselves to a particular field of application only in the form of a sophisticated lightweight stiff structure and the requirements are such that the structure must be of plastics, e.g., in a radome. In other instances, the economics of fabrication and erection of a plastics lightweight structure and the intrinsic appearance and other desirable properties make it preferable to other materials. ... 

The use of folded plates to form stiff structures has become one of the most important developments in architecture, as much because of the variety of interesting enclosures and support shapes possible as the efficient use of materials to impart stiffness. Benjamin gives a large number of examples of folded plate structures using FRP materials. They are one of the preferred materials for this type of construction because they can be readily fabricated into the required complex geometries. 

Folded plate structures — stripes of plate jointed at the edges — are not really shells at all, but in functioning and in the way they can be treated are quite close to cylindrical shells. The edges of the dome shell of the reactor vessel will, sometimes, develop the shape of the folded plates. 

In the design and construction of a catilever folded plate structure in Nanjing gym. SFRC was also used to reduce the crack width and the deformation. The steel fibre contents used were lOOkg/m and 150kg/m, which improved the bending... 

FIGURE 27. (A) Crystal structure (1VR3) of house mouse adreductone dioxygenase showing a cupin fold (Plate LI). (B) The active site showing a bound Ni(II) and two coordinated water molecules (red sphere, Plate LII)... 

The stresses in some folded structures can be determined with acceptable accuracy by applying elementary beam theory to the overall cross-sections of the plate assemblies. When assemblies are plates whose lengths are large relative to their cross-sectional dimensions (thin-wall beam sections, ribbed panels, and so on) and are in large plates... 

According to Hosemann-Bonart s model8), an oriented polymeric material consists of plate-like more or less curved folded lamellae extended mostly in the direction normal to that of the sample orientation so that the chain orientation in these crystalline formations coincides with the stretching direction. These lamellae are connected with each other by some amount of tie chains, but most chains emerge from the crystal bend and return to the same crystal-forming folds. If this model adequately describes the structure of oriented systems, the mechanical properties in the longitudinal direction are expected to be mainly determined by the number and properties of tie chains in the amorphous regions that are the weak spots of the oriented system (as compared to the crystallite)9). 

Figure 1. Hierarchical model of chromosome structure, (a) In interphase cells, DNA is packed in a nucleus as forming nucleosome and chromatin, (b) DNA forms nucleosome structure together with core histone octamer, which is then folded up into 30nm fiber with a help of linker histone HI. This 30 nm fiber is further folded into 80 nm fiber and 300 nm loop structures in a nucleus. In mitosis, chromosome is highly condensed. Proteins which are involved in each folding step are indicated above and non-protein factors are indicated below, (c) The amino acid sequences of histone tails (H2A, H2B, H3 and H4) are shown to indicate acetylation, methylation and phosphorylation sites. (See Colour Plate 1.)...

Plate 27. Large-scale image of the Au(lll)-22X-y/F recc truction. The Au(lll) surface reconstructs at room temperature to form a 22Xy/3 structure, which has a two-fold symmetry. On a large scale, three equivalent orientations for this reconstruction coexist on the surface. Furthermore, on an intermediate scale, a herring-bone pattern is formed. See Barth et al. (1990) for details. Original image be courtesy of J. V. Barth. 

First identified in 1986 as the catalytic active element in the replication cycle of certain viruses, the hammerhead ribozymes (HHRz) are the smallest known, naturally occurring RNA endonucleases They consist of a single RNA motif which catalyzes a reversible, site-specific cleavage of one of its own phosphodiester bonds . Truncation of this motif allowed a minimal HHRz to be constructed which was the very first ribozyme to be crystallized. HHRz minimal motifs are characterized by a core of eleven conserved nucleotides (bold font in Figure 20) from which three helices of variable length radiate. Selective mutation of any of these conserved residues results in a substantial loss of activity. In the absence of metal ions the structure is relaxed ( extended ), but upon addition of Mg +, hammerhead ribozymes spontaneously fold into a Y-shaped conformation (Figure 20 Color Plate 3). ... 

A display of every atom in a protein is often forbidding and incomprehensible. Viewers are interested in some particular aspect of the structure, such as the active site or the path of the backbone chain, and may want to delete irrelevant parts of the model from the display. Display commands allow viewers to turn atoms on and off. Atoms not on display continue to be affected by rotation and translation, so they are in their proper places when redisplayed. Viewers might eliminate specific atoms by pointing to them and clicking a mouse, or they might eliminate whole blocks of sequence by entering residue numbers. They may display only alpha carbons to show the folding of the protein backbone (refer to Plate 5), or only the backbone and certain side chains to pinpoint specific types of interactions. 

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