Some general results concerning the critical exponents of percolation processes

Summary In this paper we will give some results concerning the critical exponents of percolation processes which are valid for any model. These results show that in several respects the behavior which occurs for percolation on the binary tree provides bounds on one side for what happens in general. These results and their proofs are closely related to their analogues for the Ising model.Alfred P. Sloan Fellow. This work partially supported by NSF grant MCS 80-02732.     

The application of C-N.M.R. spectroscopy to the determination of the stereochemistry of Diels-Alder adducts

Long-range (³J) ¹³C-H coupling is a reliable probe to evaluate the stereochemistry of cycloaddition products. The method is best applied to carbonyl containing adducts but not restricted to them. Several structures have been revised and new ones evaluated.     

Absolute Konfiguration von Picrocrocin

By correlation with (?)-3-methoxy-β-jonone picrocrocin has been shown to have R-configuration.     

Caged Thiophosphotyrosine Peptides

No Abstract     

Oxygen isotope corrections for online delta(34)S analysis

Elemental analyzers have been successfully coupled to stable-isotope-ratio mass spectrometers for online measurements of the delta(34)S isotopic composition of plants, animals and soils. We found that the online technology for automated delta(34)S isotopic determinations did not yield reproducible oxygen isotopic compositions in the SO(2) produced, and as a result calculated delta(34)S values were often 1-3 per thousand too high versus their correct values, particularly for plant and animal samples with high C/S ratio. Here we provide empirical and analytical methods for correcting the S isotope values for oxygen isotope variations, and further detail a new SO(2)-SiO(2) buffering method that minimizes detrimental oxygen isotope variations in SO(2).     

Selective nitrogen protection of hydroxyalkylbenzimidazoles using 2,2,2-trichloroethylchloroformate

A method for selective N-protection of hydroxyalkylbenzimidazoles using 2,2,2-trichloroethylchloroformate (Troc-Cl) applicable to various alkyl chain lengths has been developed. In the specific case of 5-(1-[2,2,2-trichloroethyl formyl]-benzimidazol-2-yl)-propan-1-ol, migration of Troc from the benzimidazole to the primary alcohol occurs in the presence of triethylamine, allowing the choice of selective N-Troc or O-Troc protection.