Stress Spider

Numbers in the columns refer to corresponding numbered curves in the Stress Spider ViN simply means any input voltage is appropriate ViN 50 is input voltage at which D = 0.5 ... 

The spinning of silk monofilaments from a concentrated aqueous solution (>20% protein) of recombinant spider silk protein might be the best way to generate stress-... 

Knight, D. P., Knight, M. M., and Vollrath, F. (2000). Beta transition and stress-induced phase separation in the spinning of spider dragline silk. Int. J. Biol. Macromol. 27, 205-210. 

The next example of the mechanical properties of a standard polypeptide structure is that of silk, which is composed of extended (1 sheets. The stress-strain curve for drag silk of the spider (Figure 6.3) shows an ultimate tensile strength (UTS) of about 800MPa, a modulus of about 7.0 GPa, and a strain at failure of about 30%.The value of the UTS and modulus appears to be higher than that of collagen as we show in Chapter 7 after correction for orientation effects and other complications the values for collagen are... 

Weld lines (also known as knit lines) are a potential source of weakness in molded and extruded plastic products. These occur when separate polymer melt flows meet and weld more or less into each other. Knit lines arise from flows around barriers, as in double or multigating and use of inserts in injection molding. The primary source of weld lines in extrusion is flow around spiders (multiarmed devices that hold the extrusion die). The melt temperature and melt elasticity (which is mentioned in the next section of this chapter) have major influences on the mechanical properties of weld lines. The tensile and impact strength of plastics that fail without appreciable yielding may be reduced considerably by in doublegated moldings, compared to that of samples without weld lines. Polystryrene and SAN copolymers are typical of such materials. The effects of weld lines is relatively minor with ductile amorphous plastics like ABS and polycarbonate and with semicrystalline polymers such as polyoxymethylene. Tliis is because these materials can reduce stress concentrations by yielding [22]. 

Recent physico-chemical investigations of such materials are somewhat contradictory. Japanese workers, with a strong tradition in such work, suggest that certain silkworm fibroins are branched, whereas different workers, stress the liquid-crystalline nature of other materials, such as spider silks, and the parallels vwth linear synthetic liquid-crystalline polymers. Perhaps it is fair to say, as in other areas discussed in this article, that there is still a severe shortage of basic information. 

Cause Spider mites. Mites feeding on leaves remove plant nutrients fine webbing may appear on foliage. Use strong sprays of water when first symptoms appear. Mites multiply quickly and prefer drought-stressed, dusty plants. Keep gladiolus well-watered and healthy. Treat severe infestations of spider mites with avermectins, citrus oils, insecticidal soap, neem, or pyrethrin. Remove and destroy badly infested plants. 

Argiope The spider will bite if stressed or provoked. Initial symptoms include sharp pain and swelling. Induration with a surrounding erythema can occur. The bite may cause a necrotic lesion, but no systemic symptoms expected. 

Specific phobias are perhaps the most familiar of the anxiety disorders, and are char-, acterized by a disproportionate fear of an object (e.g., spider, snake) or situation (e.g., flying, receiving an injection). When the stimulus is confronted it elicits an intense anxiety reaction, which the sufferer recognizes to be excessive but is unable to moderate. Prophylactic use of anxiolytics for predictably stressful situations is helpful, but in the longterm, medication is less successful than behavioral therapy in the treatment of specific phobias. 

Spider lines are usually visible to the naked eyes as linear surface depressions. They are stress concentrators. Figures 15.8-15.11 show the development of an oxidative crumbling of a composite deck board with clearly visible cracks along spider lines, and Figure 15.12 shows a catastrophic failure of WPC board due to oxidative decomposition. 

Fig. 5. Spider-plot display of geochemical data corresponding to typical light and heavy oils that have thermal maturity significance. The averaged values with abbreviations are reported in Table 3. These results show that despite the difference in physical properties, the oils were generated at similar levels of thermal stress.

Table 1 Mechanical properties silkworm and spider silks. Values are in engineering stress and strain. All spider silk data is measured from Argiope argentata silks.

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