Stiffness “persistence

In real pol3uners the bonds cannot assume arbitrary directions but there are fixed valence angles between them. In addition, rotation about bonds is not entirely free, because the potential energy shows minima and maxima as a function of the rotation angle. To account for these effects, the above equations may be modified with a rigidity constant which depends on the architecture of the chain. If we introduce a stiffness ["persistence ) parameter p, we may write... 

Adverse effects of immunoglobulin vary with the route of administration. Following IMIG, pain, tenderness, and muscle stiffness persisting for hours or days are common. Repeat courses may cause sensitization with resulting allergic reactions. With IVIG, adverse... 

As discussed in the last 3 years, polysaccharides behave in solution under a worm like chain [26] the local stiffness of the chain is characterized by a persistance length (Ip) the larger Ip is, the larger the chain deviates from the gaussian behaviour in the usual molecular weight range of these natural polymers [27], This makes difficult to use the relations given in litterature for synthetic... 

Increase of Persistence Length and Parallel Orientation of Stiff Segments (PET)... 

Region I here the molecular chains partly assume helical (stiff) conformation from random coils where the persistence length gradually increases. 

Joint stiffness typically is worse in the morning, usually exceeds 30 minutes, and may persist all day. 

In this part, two series of 44 copolymers with coiled main-chain structures and 45 copolymers with stiff main-chain conformations were described. It was concluded that both optically inactive 42 and 43 adopt helical conformations with an equal proportion of P and M screw senses by means of UV and CD spectra as well as molecular mechanics calculations. A marked positive cooperative induction effect of the preferential screw sense in 44 and 45 copolymers was found. However, there is a marked difference in the helical cooperativity between 44 and 45, probably because of the differences in their global and local conformations. This difference can be related to the persistence of the helical conformation against defects allowing change of... 

Note 1 The persistence length is a characteristic of the stiffness of a chain in the limit of infinite chain length. 

The lethal oral dose in humans is probably around 100, but doses as low as 16 mg have reportedly been fatal whereas doses of 2 000 mg have been survived. After ingestion, effects usually occur within 10-30 minutes and include stiffness of the face and neck muscles and increased reflex excitability. Strychnine acts by altering nerve impulses in the spinal cord, resulting in a decreased threshold for stimulation, and, hence, a hyperexcitable state. Any sensory stimulus may produce a violent motor response that, in the early stages of intoxication, tends to be a coordinated extensor thrust and, in later stages, may be a tetanic convulsion with opisthotonos anoxia and cyanosis develop rapidly. Between convulsions, muscular relaxation is complete, breathing is resumed, and cyanosis lessens. Because sensation is unaffected, the convulsions are painful and lead to overwhelming fear. As many as 10 convulsions separated by intervals of 10-15 minutes may be experienced, but death often occurs after the second to fifth convulsion, and even the first convulsion may be fatal if sustained death is commonly due to asphyxia.If recovery occurs, it is remarkably prompt and complete despite the violence of the illness muscle soreness may persist for a number of days. ... 

In patients who have persistent night pain or morning stiffness, giving a large portion, up to a maximum of 100 mg of the total daily dose at bedtime, may help to relieve pain. The total daily dose should not exceed 200 mg. 

The analysis described above is useful for modelling colligative properties but does not address polyelectrolyte conformations. Polyelectrolyte conformations in dilute solution have been calculated using the worm-like chain model [103,104], Here, the polymer conformation is characterized by a persistence length (a measure of the local chain stiffness) [96]. One consequence of the... 

Since Robinson [1] discovered cholesteric liquid-crystal phases in concentrated a-helical polypeptide solutions, lyotropic liquid crystallinity has been reported for such polymers as aromatic polyamides, heterocyclic polymers, DNA, cellulose and its derivatives, and some helical polysaccharides. These polymers have a structural feature in common, which is elongated (or asymmetric) shape or chain stiffness characterized by a relatively large persistence length. The minimum persistence length required for lyotropic liquid crystallinity is several nanometers1. 

Table 1. Persistence length q and molar mass per unit contour length ML for liquid-crystalline stiff-chain polymers...

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