Vertical stabilisation

Interactions between 7t-systems have long been observed in crystal structures of aromatic molecules and, for example, play a role in stabilising DNA through vertical base-pair interactions. They are also involved in the intercalation of drugs into the grooves of DNA. Such interactions have also been exploited in many synthetic host-guest systems. Previous rationales for the occurrence of k-k interactions have included explanations based on solvophobic,electron donor-acceptor as... 

That it is this group exclusively which migrates, may reflect vertical charge stabilisation by the donating effect of the Si-Si ff-electrons to the vacant p-orbitals of the silylcarbenes. 

Fig. 1 Qualitative cross section through the potential energy surface, along JT active vibration Qa, Definition of the JT parameters - the JT stabilisation energy, Eji, the warping barrier, A, the JT radius, iJjx, the energy of the vertical Frank-Condon transition, fc...

Turning to Table I it is obvious that by far the largest share (75% according to Woodwell et al. 1978) in the global marine net primary production comes from the open oceans and hence from the phytoplankton in that system. It is at the same time remarkable that this production is out of proportion in relation to the phytoplankton biomass 26% of the total aquatic marine plant mass could be estimated in the open ocean. It should be realised that the distribution of phytoplankton in the sea is rarely uniform and frequently extremely patchy. Horizontally, patches are usually elliptical and vary in size from a few metres to hundreds of kilometres across. Long narrow bands or streaks, a few metres in width, are common and may form a pattern superimposed on that of the patches. Under conditions of strong mixing, vertical distribution of phytoplankton may be uniform, but if the water column becomes stabilised, non-motile forms denser than water will... 

Once the temperature has stabilised, the sample is hydrated at constant volume through the bottom face with deionised water injected at a pressure of 0.6 MPa, while the upper outlet remains open to atmosphere. At the same time, the swelling pressure exerted by the clay is measured by a load cell installed in the loading frame and the vertical deformation of the specimen is measured by two LVDT s. The values of load, strain and water exchange are automatically recorded. The final density may differ slightly from the nominal one due to the small displacement allowed by the equipment. 

The rates of thinning of vertically-supported, thin liquid films of polyol solutions of various silicone surfactants have been measured [37]. It was found that the rate for films stabilised by a trimethylsilyl-capped polysilicate (TCP a highly branched silicone not containing polyethers), was much lower than that for the films stabilised by common silicone polyether copolymer surfactants. The retardation of drainage rate was correlated with an increase in surface viscosity. Furthermore, it was noted that PU foams prepared using TCP were significantly more stable than those containing the commercial surfactants. 

As reported in the literature, interference fringes in many vertical aqueous films are horizontal with little curvature. These films also displayed mobile surfaces, rapid and extensive surface flows and rapid rates of drainage [22, 28-30]. These features were all linked to the presence of a low surface viscosity. Based on our experimental observations, the PU films stabilised by DABCO DC 198 have low surface viscosities. This conclusion is supported by reports of measurements of low surface viscosities in polyol solutions containing silicone polyether surfactants [12, 15, 38]. 

We can answer the last question if consider a constraction of the so-called surface stabilised ferroelectric liquid crystal cell or simply SSFLC ceU [9]. Such SSFLC cell is only few micrometers thin and, due to anchoring of the director at the surfaces, the intrinsic helical stmcture of the SmC is unwound by boundaries but a high value of the spontaneous polarisation is conserved. The cell is con-stracted in a way to realise two stable states of the smectic C liquid crystal using its interaction with the surfaces of electrodes, see Fig. 13.6a. First of all, in the SSFLC cell, the so-called bookshelf geometry is assumed the smectic layers are vertical (like books) with their normal h parallel the z-axis. Then the director is free to rotate along the conical surface about the h axis as shown in Fig. 13.6b (Goldstone mode). It is important that, to have a bistability, the director should be properly... 

Universiti Tun Hussein Onn Malaysia (UTHM) sits on deep deposit of soft marine clay with low strength and high compressibility. Pre-treatment of the soil by ground improvement is necessary before construction works can commence on these grounds. Various ground improvement techniques are available in the market, such as vertical drains with surcharge, stone columns, mass replacement, stabilisation, etc. 

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