Reflection shielding effectiveness

Then, the total shielding effectiveness (EM SE) and reflective shielding effectiveness (EM SER) were obtained as ... 

It can be seen that, in all cases, relaxation rates are directly proportional to (Aa). Because Aa reflects the anisotropy of the shielding tensor and because the chemical shift originates from the shielding effect, the terminology Chemical Shift Anisotropy is used for denoting this relaxation mechanism. Dispersion may be disconcerting because of the presence of Bq (proportional to cOq) in the numerator of and R2 (Eq. (49)). Imagine that molecular reorientation is sufficiently slow so that coo 1 for all considered values of coo from (49), it can be seen that R is constant whereas R2 increases when Bq increases, a somewhat unusual behavior. 

Electromagnetic interference shielding effectiveness of about 18 dB was achieved with 10 vol% MWCNT-PMMA film which was found to be primarily an EMI absorbing composite material. Figure 7.15 shows the variation of EMI shielding effectiveness due to reflection... 

Yuen et al. 2008 (43) MWCNT CVD CNT Company, Incheon, Korea As-received In situ method Ex situ method CNT Loading levels 0.25 to 4.76 wt% Film Bulk Film Bulk Electrical Conductivity Percolation threshold 0.25 wt% for in situ prepared composites Percolation threshold 0.74 wt% for ex situ prepared composites EMI SE (2-18 GHz) 32.06 dB at 2.18 GHz for bulk composite prepared by in situ method 58.73 dB at 14.84 GHz for 10 layers of stacked composite film prepared by in situ method Higher EMI shielding effectiveness of layered composite attributed to energy loss by multi-reflections in the layered composites... 

A small, but resolvable splitting of the resonance line for the tris-chelate complexes of iron(II) is observed (235, 261). In the case of Fe(II)(bipy)3Cl2 AEq (0.34 mm sec ) has been shown to be independent of temperature (29S°-145°K) to within experimental error, although for the series Fe(II)(phen)gX2 AEq was shown to vary slightly with the anion X (207). The small quadrupole splitting presumably reflects the symmetry of the cations (261). Epstein (235) has compared the spectra of Fe(bipy) +, Fe(phen) +, and Fe(phen-R) + where R = 5-nitro, 5-chloro, 5,6-dimethyl, or 3,4,7,8-tetramethyl. Since in such a closely related series the d-electron shielding effects should be similar, it was considered that the isomer shift (8) should be a measure of covalent bond strength. The... 

For high-temperature systems, radiative heat loss can be very significant. In conventional systems, reflective shields or radiation mirrors and low-emissivity material are commonly used to mitigate radiative heat loss. It is expected that similar approaches would be effective in microreactors as well. ... 

Even more interesting is the shielding effect on H-2 and H-4 these chemical shifts are shifted upfield. This must reflect the other side of oxygen s personality, the donation of electron density through a resonance effect. Drawing the resonance forms clearly shows that the electron density at H-2 and H-4 (and presumably H-6) increases through this donation by resonance, in perfect agreement with the NTMR results. As we will see in Chapter 17, in most cases, resonance effect trumps inductive effect. 

A somewhat different aspect of the hydrophobic shielding effect of alkyl substituents was reflected in the relative hydrophilicity of aliphatic amine-cured resins. A standard room temperature-curing polyamine, triethylenetetramine (TETA), was used to cure a series of resins at room temperature. The... 

The absence of CIDNP resulting from pairs R -MgX speaks against -MgX as an intermediate in solution [511. The observed CIDNP reflects multiple effects front [R- R- pairs only. (R- -MgX would have a non-/m> value of Ag and would give rise to net effects, which arc mu seen. However, it is conceivable that R- -MgX pairs do not generate C lDNP Ag eould be so large that CIDNP is attenuated. or -MgX eould remain at the surface where a metallic shielding effect prevents CIDNP, etc. 

In early nineties nice correlation was found between the particle size and the enantioselectivity, i.e., the larger the particle size of Pt the higher the enantioselec-tivity [5]. This correlation suggested that relatively large number of Pt sites has to be involved in the enantio-differentiation step. This view is reflected in model I. Contrary to that in the shielding effect model (model II), as it has been discussed above, there is no preference with respect to the size of the Pt nanoclusters, as in principle, the site requirement to hydrogenate the formed supramolecule (i.e., the substrate-modifier complex) is relatively small [8-10]. 

Compounds. Estimations of the degree of protonation of phosphine oxides vary, depending on whether conclusions are drawn from n.m.r. or n.m.r. spectra. A comparison of six oxides indicates that 8p reflects direct protonation to a greater extent than Sh, which depends also on the state of the molecule as a whole.A comparison of the shielding effects of oxides and sulphides (11 X = O or S) showed that the deshielding... 

Dramatic downfield shifts accompany the cleavage of P-substituents with formation of phospholide ions. These shifts are considerably further downfield than those for simpler phosphide ions, and have been taken to be a reflection of strong electron delocalization in the phospholide ion (see Section 2.15.2). Data are collected in Table 6, where it will be seen that typical shifts fall in the region -t-70 to -t-100. Once again the 3,4-dimethyl shielding effect is present and indeed is of the largest size (A 21.4 ppm) of all families examined. Phospholide ions with this substitution have shifts in the range -t- 50 to -t- 60. 

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