All Clear

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Figure 8.25 shows the AXn,m. ii,iii Auger spectrum of a gaseous mixture of SFe, SO2 and OCS, all clearly resolved. The three intense peaks are due to sulphur in a >2 core state, but there are three weak peaks due to a core state also. The S 2p X-ray photoelectron spectrum of a mixture of the same gases is shown for comparison, each of the three doublets being due to sulphur in a 1/2 or 3/2 core state. 

A small isotope effect has been observed in nitration of benzene by nitronium borofluoride in tetramethylene sulphone at 30 °C (kH/kD = 0.86) and this has been attributed to a secondary effect of the change in hybridisation from sp2 to sp3 of the ring carbon during the course of the reaction109. However, naphthalene gives an isotope effect of 1.15 under the same conditions, and anthracene a value of 2.6115. It does not seem at all clear why these relatively unhindered and normally more reactive molecules should give rise to an isotope effect when benzene does not. 

Questions such as, for example, whether sphalerite contains Zn++ and S= ions or has a covalent structure similar to that of diamond, and whether ionic or covalent bonds are present in complexes such as [FeF% —, [Fe(CN)e]=, etc., have been extensively discussed it has, indeed, until recently not been at all clear whether or not they could be definitely... 

The superstructure of smooth muscle actin filaments is differentiated from those of striated muscle by the absence of the troponins and the lateral organization by association of the filaments with dense bodies instead of with the Z-line. How these differences are encoded is again not at all clear. However, the myofibrillar structure and the alignment of the alternating actin and myosin filaments is apparently due primarily to dense bodies and the actin-actinin macrostructures. As the bent dumbbell shaped actins assemble into filaments they are all oriented in the same direction. The S-1 fragments of myosin will bind to actin filaments in vitro and in... 

In the sarcoplasm of smooth muscle cells there is a membrane bound compartment usually referred to as the SR by analogy with skeletal muscle. However, it is not at all clear that the interior of these membrane-bound regions are continuous as they are in skeletal muscle. The primary properties of this system seem to be quite similar to those of the endoplasmic reticulum of many other cell types. In general, calcium is concentrated into the membrane-bound reticulum and then released to initiate the characteristic action of the cell. 

The functions of these different phases of sleep are not at all clear but chronic sleep deprivation does eventually lead to death. It seems to be the slow-wave component of sleep (SWS) that is vital and it is thought to serve a restorative purpose. This would be consistent with its greater occurrence during the early stages of the sleep cycle when hormone secretion supports anabolic metabolism. If subjects are wakened every time they enter a period of REM sleep (evidenced by the EEG) there appears to be no overt harmful effect on their behaviour. In fact, REM sleep deprivation has even been used, with some claims of success, as a treatment for minor depression. However, there is an unproven belief that REM sleep is important for memory consolidation. 

Of course, it is not at all clear how one should select the weighting matrices Q i=l,...,N, even for cases where a constant weighting matrix Q is used. Practical guidelines for the selection of Q can be derived from Maximum Likelihood (ML) considerations. 

Pecora noticed that the phase information of C is lost in the original constraints [i.e. P2 = P Tr P = N], but found it not at all clear . Here, we showed in which way one might take into account the loss of the phase information in C when calculating the number of conditions to uniquely determine C one has to impose, over and above the constraints arising from fixing the projector, the conditions to determine a particular unitary transformation in the TV-dimensional subspace, apart from the phases of the basis functions which are physically meaningless in the context of Quantum Mechanics. 

The signaling complex formed around the TCR and the branching pathways that emanate from it resemble the mechanisms used by the growth factors. However, the destinations of these pathways are not all clear. The PLC-y pathway (DAG, IP3, and elevation of intracellular free Ca2+) leads to activation of the phosphatase calcineurin, which activates the transcription factor NF-AT (nuclear factor of activated T cells). This is essential for clonal expansion of T cells because of its pivotal role in the induction of IL-2 expression. NF-AT requires the assistance of the activator protein 1 (AP-1) complex in order to drive expression of IL-2. 

If, for example, the reaction at pH 7 between pyruvate anion (70) and hydroxylamine, NH2OH, is followed by monitoring the infra-red spectrum of the reaction mixture, then the absorption characteristic of C=0 (vmax 1710 cm-1)—in the starting material (70)—is found to disappear completely before any absorption characteristic of C=N (vmax 1400 cm-1)—in the product oxime (71)—appears at all. Clearly an intermediate must thus be formed, and it seems probable that this is a carbinolamine (72 such a species has actually been detected by n.m.r. spectroscopy, in the reaction of MeCHO with NH2OH) ... 

It seems obvious that groups attached to the ends of a silicon-carbon double can scramble under a variety of conditions, but the limited observations to date vary so widely in experimental conditions required that it is not at all clear what the specific requirements are for this process to occur. 

In Table 22 however only the assignments for groups A and A" are listed since for the other two groups the precise correspondences are not at all clear. 

But here is what Philip Brown did He took a different tack on the question. He set up and performed an experiment wherein he took different sugars (fructose, glucose, and sucrose) and made up solutions by dissolving them in water, each at five different concentration levels, and made solutions using all combinations of concentrations. That gave an experimental design with 125 samples. He then measured the spectra of all of those samples. Since the samples were all clear solutions there were no extraneous effects due to optical scatter. 

Commonly, it is asserted that upward transitions from the lower adiabat to the upper one should be less likely than downward transitions because of the funneling property of the intersection [144,145]. This is clearly seen in the usual model conical intersection—as seen, for example, in Fig. 1 of Ref. 146, where there is (a) a well, or funnel, in the upper adiabat which guides the wavepacket to the intersection and (b) a peak on the lower adiabat which tends to guide the wavepacket away from the intersection. The potential energy surfaces shown in Fig. 7 differ from this canonical picture, and in particular it is not at all clear that the wavepacket on the lower adiabatic state will be funneled away from the intersection. For the conditions chosen in our calculations, we... 

With regard to the testing and regulation of new chemicals, it is not at all clear that, with the exception of the most fundamental goal of protecting man and the environment from certain chemical risks, the major parties involved in these issues have reached an accord on fundamentals. In fact, experience to date indicates that real "harmonization" often neither reflects nor... 

Some obscurities. Each of the reactions mentioned has been identified in at least one system, but there are very many obscurities to be cleared up. For example, transfer by methyl vinyl ether, phenyl vinyl ether, vinyl acetate and some of the corresponding polymers in the polymerization of styrene by stannic chloride has been studied, but the mechanism is not at all clear [124]. 

Although this work is still incomplete, it shows that some tertiary oxonium ions are formed in the reaction, but that by far the greater part of the active species are secondary oxonium ions. The origin of the tertiary oxonium ions, which yield the involatile phenyl ether by reaction with C6H5CT, is not at all clear at present. Some may be formed from an impurity in the monomer and others may arise from a slow side-reaction. 

The first use of supercritical fluid extraction (SFE) as an extraction technique was reported by Zosel [379]. Since then there have been many reports on the use of SFE to extract PCBs, phenols, PAHs, and other organic compounds from particulate matter, soils and sediments [362, 363, 380-389]. The attraction of SFE as an extraction technique is directly related to the unique properties of the supercritical fluid [390]. Supercritical fluids, which have been used, have low viscosities, high diffusion coefficients, and low flammabilities, which are all clearly superior to the organic solvents normally used. Carbon dioxide (C02, [362,363]) is the most common supercritical fluid used for SFE, since it is inexpensive and has a low critical temperature (31.3 °C) and pressure (72.2 bar). Other less commonly used fluids include nitrous oxide (N20), ammonia, fluoro-form, methane, pentane, methanol, ethanol, sulfur hexafluoride (SF6), and dichlorofluoromethane [362, 363, 391]. Most of these fluids are clearly less attractive as solvents in terms of toxicity or as environmentally benign chemicals. Commercial SFE systems are available, but some workers have also made inexpensive modular systems [390]. 

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