H-T placement

The glass transition temperature of H-H PS is 97°C. while that of H-T atactic H-T PS is 98°C. and that of isotactic H-T PS is 92°C. The theta temperature of H-H PS is 19°C. in cyclohexane, 16°C. lower than the theta temperature of H-T PS. The Mark-Houwink parameter a of H-H PS was found to be 0.61, the same as that for isotactic PS but somewhat lower than the 0.71 obtained for atactic H-T PSg(50). The nonperturbed dimension of H-H PS is 805 x 10" A as compared tOgthe 780 x 10" A for the isotactic H-T PS and 660 X 10" A for H-T PS, all those numbers indicate that there is a decreased flexibility of the chain when the phenyl substituents are in 1,2-position (H-H placement) but at the same time the polymer with H-H placement is more soluble as compared to the polymer with H-T placements. 

This type of arrangement (III) is usually referred to as a head-to-tail (H-T) or 1,3-placement of monomer units. An inversion of this mode of addition by the polymer chain propagating alternately via Eqs. 3-9 and 3-8 would lead to a polymer structure with a 1,2-placement of substituents at one or more places in the final polymer chain. 1,2-Placement is usually... 

It should be noticed that in the previous considerations we write x and x for the placement of the material particle and its velocity independent of the dimension of the body, that is, whether the body is three-dimensional. This kind of notation will be used later as well except when one-dimensional or two-dimensional continuum is observed. It is the case, for instance, when the material surface is contained in three-dimensional body. In that case x and x are quantities which are related to two-dimensional body. With = (H, t) we denote the position of the material particle of three-dimensional material body. Also with... 

Multiple impellers are recommended if H/T 1.2 or if Ap > 150 kg/m. Assuming a less dense dispersed phase, the second or top impeller often is a hydrofoil placed midway between the RDT and the surface of the liquid. This impeller produces high flow at low power, provides excellent circulation, and complements the flow pattern produced by the RDT. The diameter of the second impeller is usually greater than the RDT, typically D/T > 0.45. A good practice is to distribute the total power to f 20% for the hydrofoil and f 80% for the RDT. Since the power number, Np, is known for each turbine, setting the power distribution enables the diameter of the hydrofoil to be determined. The vertical position of the upper turbine must ensure that fluid reaches the lower impeller, but must avoid gas entrainment that could occur if placement is too close to the hquid surface. Flow from a PBT does not complement that from a RDT and is therefore not recommended. Power requirements are discussed in Section 12-7.3. Table 12-6 lists equipment options for different drop sizing objectives (desired result). If ds2 must be less than 30 tim, the use of a stirred tank is not recommended, so other devices are also included in the table. 

F.J.T. Burke, S.W. Cheung, I.A. Mjor, N.H.F. Wilson, Restoration longevity and analysis of reasons for the placement and replacement of restorations provided by vocational dental practitioners and their trainees in the United Kingdom, Quintessence Int. 30 (1999) 234-242. 

The signal a of methyl protons consists of two doublet resonances. The weak doublet resonance (d, 8 1.98, JH H = 6.8 Hz) at lower field is related to the erythro (isotactic) placement of the last propylene unit (4-e), whereas the strong doublet resonance (d, 8 1.95, JH H = 6.8 Hz) at higher field is related to the threo (syndiotactic) placement of the same unit (4-t),... 

Dao, T.H. (1995). Subsurface mobility of metribuzin as affected by crop residue placement and tillage method. J. Environ. Qual., 24 1193-1198. 

Xu, K., He, F.-X., Zhang, H.-G., Zhang, X.-T., Han, M.-J., Wang, C.-R., Kaneko, M., T ahashi, M., Okawada, T. Budd-Chiari syndrome caused by obstruction of the hepatic inferior vena cava immediate and 2-year treatment results of transluminal angioplasty and metalHc stent placement. Cardiovasc. Intervent. Radiol. 1996 19 32—36... 

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