Structure static

The first gel that was theorized rigorously using a model by Flory and Stockmayer is the one formed by covalent bonding [2]. In this model. [Pg.123]

In the physical gel (top), the portion with physical bonding forms clusters (crosslink domain) of finite size. [Pg.124]

In the chemical gel (bottom), the crosslink point by covalent bonding can be regarded as having dense and rare parts of crosslink points. [Pg.124]

The cascade theory can also be easily extended to crosslinked systems. The formation of crosslinked gels starts first with crosslinking a linear polymer (primary polymer) by intermolecular covalent bonds and then forming a star polymer with four branches. As the ciosslinking via intermolecular covalent bonding proceeds, the amount of branching [Pg.125]

3 A branch model of primary chain crosslinking and compression into a tree model. [Pg.126]

Salgi P and Rajagopalan R 1993 Polydispersity in colloids—implications to static structure and scattering Adv. Colloid Interface Sc/. 43 169-288... [Pg.2692]

To begin a rn olecular dyri am ics sinuiltitiori from th is static structure, HyperChern assigns velocity values that arc realistic for the molecular system at a designated temperature. [Pg.73]

The coarse-graining approach is commonly used for thermodynamic properties whereas the systematic or random sampling methods are appropriate for static structural properties such as the radial distribution function. [Pg.361]

Biological membranes provide the essential barrier between cells and the organelles of which cells are composed. Cellular membranes are complicated extensive biomolecular sheetlike structures, mostly fonned by lipid molecules held together by cooperative nonco-valent interactions. A membrane is not a static structure, but rather a complex dynamical two-dimensional liquid crystalline fluid mosaic of oriented proteins and lipids. A number of experimental approaches can be used to investigate and characterize biological membranes. However, the complexity of membranes is such that experimental data remain very difficult to interpret at the microscopic level. In recent years, computational studies of membranes based on detailed atomic models, as summarized in Chapter 21, have greatly increased the ability to interpret experimental data, yielding a much-improved picture of the structure and dynamics of lipid bilayers and the relationship of those properties to membrane function [21]. [Pg.3]

Farag, M. M. 1997 Properties Needed for the Design of Static Structures. In ASM International, ASM Handbook No. 20 - Materials Selection and Design, 10th Edition. OH ASM International. [Pg.385]

Chemical shifts and coupling constants reveal the static structure of a molecule relaxation times reflect molecular dynamics. [Pg.10]

Finite temperature being reduced to zero Kelvin, i.e. the use of static structures to represent molecules, rather than treating them as an ensemble of molecules in a distribution of states (translational, rotational and vibrational) corresponding to a (macroscopic) temperature. [Pg.401]

In a previous paper the Car-Parrinello (CP) technique was applied to the equimolar NaSn alloy [6]. In a further publication [7] we extended these investigations to a wide range of compositions ranging from 20% up to 80% of sodium and discussed the static structure factors and the behaviour of the Zintl anions (Sn ) in the molten alloys. [Pg.278]

The obtained static structure factors agree well with the experimental ones [4], all trends of the peak positions are reproduced correctly. There are only small deviations from the experiments (i) due to the pseudopotential (slighly too small bond lengths which correspond to slightly too large peak positions in the reciprocal lattice) and (ii) correct positions but a wrong trend in the heights of the prepeaks. For a detailed description see Ref. [7]. [Pg.279]

If a lead alloy is used as a ship s hull anode, consideration should be given both to the make-up of the water in which the anode is initially passivated and that in which it will normally operate. The same consideration will apply for static structures in estuarine waters. [Pg.181]

However, despite the rather dramatic change in coordination geometry that is observed upon comparing [TpBut Me]CuCl and [TpBut]CuCl (41), only rather minor perturbations are observed in comparing the structures of the Cud) dimers [TpBut]Cu 2 (37) and [TpBut,Me]Cu 2 (22). Thus, both the average Cu-N bond lengths and also the Cu - Cu separations in [TpBut Me]Cu 2 and [TpBut]Cu 2 are very similar. Nevertheless, although the coordination environment about each copper center is similar, the 5-methyl substituent does influence the fluxional nature of the molecule in solution. Thus, whereas [TpBut]Cu 2 is fluxional on the NMR time scale at room temperature, with a static structure that is only observed at -56°C, [TpBut Me]Cu 2 exhibits a static H NMR spectrum at room temperature. Furthermore, a static spectrum for... [Pg.308]

In spite of the problems associated with the static structure, the coarsegrained model for BPA-PC did reproduce the glass transition of this material rather well the self-diffusion constant of the chains follows the Vogel-Fulcher law [187] rather nicely (Fig. 5.10),... [Pg.126]

The present analysis shows that when a thermodynamic gradient is first applied to a system, there is a transient regime in which dynamic order is induced and in which the dynamic order increases over time. The driving force for this is the dissipation of first entropy (i.e., reduction in the gradient), and what opposes it is the cost of the dynamic order. The second entropy provides a quantitative expression for these processes. In the nonlinear regime, the fluxes couple to the static structure, and structural order can be induced as well. The nature of this combined order is to dissipate first entropy, and in the transient regime the rate of dissipation increases with the evolution of the system over time. [Pg.84]

Theoretical Outline—Influence of the Static Structure on the Dynamics... [Pg.90]

Thus, the calculation of 2(Q) requires the knowledge of the partial static structure factors SaP(Q, t) and the elements PaP(Q) of the mobility matrix p(Q), which itself depend on SaP(Q,0). [Pg.92]

Equations (125) and (126) explicitly show that in the initial slope approximation the elements of the generalized mobility matrix can be expressed only in terms of integrals over the corresponding partial static structure factor. Both equations are valid as long as one assumes a Gaussian distance distribution of the distances r between the monomers i on arm a and monomers j on arm p. [Pg.93]

Fig. 47a, b. Structure and dynamics of star-shaped polymers with different functionalities, a Kratky plot of the static structure factor (S(Q, 0) Q2 vs. Q Rg. b Q(Q)/Q3 vs. Q Rg, as derived from Eqs (94) and (123), assuming Rouse dynamics... [Pg.94]

The salient feature of the experimental results is the observation of a pronounced minimum in the Q(Q)/Q3 vs. z plot. It occurs at the same position, where the static structure factor in its Kratky representation exhibits its maximum. Furthermore, the reduced line width scales with the scaling variable z in the same way that the static structure factor does. Thus, the occurrence of the minimum is directly related to peculiarities of the star architecture. [Pg.98]

At higher Q, however, where the static structure factor reveals the asymptotic power law behavior S (Q, 0) Q 1/v, the assumption of ideal conformation clearly fails. In particular, this is evident for the core (sample 1) and shell contrast conditions (sample 2). [Pg.103]

At this position, the reduced relaxation rate Q(Q)/Q3 shows a minimum for stars, where the arms are labelled completely or to 50% at the core site. For these systems the Kratky plot of the static structure exhibits a maximum at the same Q-value... [Pg.108]

After many incorrect assignments, structures 178 and 179 were eventually proposed on the basis of the IR spectrum of the former and on an X-ray structure for the latter. Static structure 178 is correct, but 179 showed equal S-S distances. Also, the H NMR spectrum of 179 showed equivalent methyls and equivalent methines. Moreover, the two S-S distances in the parent l,6,6aA4-trithiapentalene 175 are equal, and the SSS angle is 178°. It was therefore proposed that these molecules are symmetric. [Pg.516]

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