Study suggestions

An analysis of nearly 10,000 collaborative studies suggests that a reasonable estimate for a method s reproducibility is... 

Friedel-Crafts catalysts are electron acceptors, ie, Lewis acids. The alkylating ability of ben2yl chloride was selected to evaluate the relative catalytic activity of a large number of Lewis acid haUdes. The results of this study suggest four categories of catalyst activity (200) (Table 1). 

Immunosuppression induced by sirolimus (36) appears to be mediated by a mechanism distincdy different from that of either cyclosporin or FK-506. Sirolimus markedly suppresses IL-2 or IL-4-driven T-ceU proliferation. The preclinical studies suggest that sirolimus is a potent immunosuppressive agent in transplantation and autoimmune disease models. The clinical potential of this agent depends on its toxicity profile (80). 

Examples of the hydroquinone inclusion compounds (91,93) are those formed with HCl, H2S, SO2, CH OH, HCOOH, CH CN (but not with C2H 0H, CH COOH or any other nitrile), benzene, thiophene, CH, noble gases, and other substances that can fit and remain inside the 0.4 nm cavities of the host crystals. That is, clathration of hydroquinone is essentially physical in nature, not chemical. A less than stoichiometric ratio of the guest may result, indicating that not all void spaces are occupied during formation of the framework. Hydroquinone clathrates are very stable at atmospheric pressure and room temperature. Thermodynamic studies suggest them to be entropic in nature (88). 

The stoichiometric reaction of y -diisopropenylbenzene [3748-13-8] with two moles of j -butyUithium in the presence of triethylamine has been reported to produce a useful, hydrocarbon-soluble dilithium initiator because of the low ceiling temperature of the monomer (78,79) which is analogous in stmcture to a-methylstyrene however, other studies suggest that oligomerization occurs to form initiators with functionahties higher than two (80). 

The lack of independent evidence for dioxetanedione (27) (69) and later results (66,68) have diminished the likelihood that (27) plays any significant role in the chemical excitation process and attention has been redirected to peroxyoxalate (26) and its isomers. More recent studies suggest that more than one intermediate may be required (70) ie, a pool of intermediates has been suggested. 

The above stm study also discovered a facile transport of surface gold atoms in the presence of the Hquid phase, suggesting that the two-step mechanism does not provide a complete picture of the surface reactions, and that adsorption/desorption processes may have an important role in the formation of the final equiHbrium stmcture of the monolayer. Support for the importance of a desorption process comes from atomic absorption studies showing the existence of gold in the alkanethiol solution. The stm studies suggest that this gold comes from terraces, where single-a tomic deep pits are formed (281—283). 

One of the most famous chiral titanium complexes is the Sharpless catalyst (16), based on a diisopropyl tartarate complex. Nmr studies suggest that the complex is dimeric ia nature (146). An excellent summary of chiral titanium complexes is available (147). 

Transition metals have also been inserted into the aziridine ring affording derivatives (295). Stereochemical studies suggest that transfer of a proton is followed by bimolecular attack on the ring with subsequent closure on the carbonyl group (76AG(E)495). 

Recent studies suggest that mercury can cause an instant decrease in the sperm viability of fish at concentrations comparable to those which are permitted in drinking water (1 /rg C ). The bioconcentration of the metal to levels in the testis considerably higher than this from water containing only 1/30 of permitted levels" suggests that current legal limits are much too high. 

Much controversy has arisen regarding the ability of mixtures of weakly estrogenic compounds to act synergistically, notably the synergistic potential of mixtures of PCBs or of the insecticides dieldrin and toxaphene. " Recent studies suggest that the action of mixtures is at least additive. "... 

Blake, C., Serpell, L. Synchrotron x-ray studies suggest that the core of the transthyretin amyloid fibril is a continuous P sheet helix. Structure 4 989-998, 1996. 

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