SEARCH THEORY IN NATURAL RESOURCE MODELING

The role of search theory in the exploitation of natural resources is discussed in this paper. After a brief history and taxonomy of search problems, the mathematics of search is discussed. This includes underlying probability distributions, the differential equations of search, Bayesian use of search information and optimization problems in search theory. The theory is illustrated by applications in fisheries, pest control, animal foraging, and oil and mineral exploration.     

Template synthesis in the nickel(II)–thiocarbohydrazide–propanone triple system

The complexing process proceeding in the Ni^II–thiocarbohydrazide (H₂N–H–NC(=S)–NH–NH₂)–propanone triple system in EtOH solution and nickel(II)hexacyanoferrate(II) gelatin-immobilized matrix has been studied. It has been found that in the first case, template synthesis leading, as a minimum, to formation of three coordination compounds of Ni^II with (N,N,S,S)-donor tetradentate ligands having NiL¹, NiL² and NiL³compositions where L¹ is 4,6,6-trimethyl-2,3,7,8-tetraazanonen-3-di(thiohydrazide)-1,9, L² is 4,6,6,12-tetrametyl-1,9-dithio-2,3,7,8,10,11-hexaazatridekadien-3,11-hydrazide-1 and L³ is 2,8,10,10,16-pentamethyl-5,13-dithio-3,4,6,7,11,12,14,15-octaazaheptadekatrien-2,7,15 is observed, whereas in the gelatin-immobilized matrix, a complexing process in the system considered does not occur.     

Oligomérisation anionique de l'ethylène. I. Etude cinétique

A kinetic study of ethylene oligomerization in hexane, in the presence of n-BuLi–TMEDA complexes, allowed us to suggest a new mechanism for anionic ethylene oligomerization. n-BuLi and n-Bu(CH₂CH₂)Li species have the same reactivity. The RLi–TMEDA complex in a 1-to-1 stoichiometry is the active species. The following kinetic equation has been established: It reflects the intervention of associated species (n-BuLi–TMEDA)₂ as well as the influence of the concentration of the complexing agent on the kinetics of oligomerization.     

Chemische Vitamin D<Subscript>3</Subscript>-Bestimmung in Lebertran

The different aspects of Vitamin D₃ determination and the data reported in the literature are discussed. The spectrophotometric determination of Vitamin D₃ in cod-liver oil is carried out after the alkaline saponification, extraction of unsaponified parts, precipitation of accompanying sterols and the column- and thin-layer chromatographic purification and separation of vitamin D₃ on 40 cm plates from other vitamins. The dyestuff α-naphtholbenzein is suited well as standard substance for the better location and identification of vitamin D₃ zone on the thin-layer plate. The results obtained from the chemical method were checked through the simultaneous biological determination.     

Efficient and practical Ag-catalyzed cycloadditions between arylimines and the Danishefsky diene

An efficient Ag-catalyzed method for asymmetric addition of the Danishefsky diene to various aryl imines to afford cycloadducts in > or =89% ee and > or =85% isolated yield is reported. Reactions are effected with 0.1-1 mol % catalyst (4 degrees C), and the chiral ligand is readily prepared from commercially available materials, including the inexpensive i-Leu. These catalytic asymmetric cycloadditions can be carried out without the use of solvent or with undistilled THF in air. A first generation supported chiral catalyst that effectively promotes the cycloaddition reaction and can be recycled (five cycles) is described.     

Stereoelective polymerization of D,L-lactide using N-heterocyclic carbene based compounds

A new Zn alkoxide catalyst supported by an N-heterocyclic carbene rapidly polymerizes D,L-lactide (D,L-LA) to heterotactic enriched poly(lactide)(PLA), while the free carbene and analogs instead yield highly isotactic enriched PLA.     

Stoichiometric and catalytic deuterium and tritium labeling of "unactivated" organic substrates with cationic Ir(III) complexes

[reaction: see text] Ir(III) complex [Cp(PMe(3))IrMe(CH(2)Cl(2))][BAr(f)] (1) was used to introduce deuterium stoichiometrically into substituted naphthalene/benzene templates and several "drug-like" entities. The exchange process is tolerant of a wide array of functional groups. Labeling of warfarin using subatmospheric pressures of T(2) led to specific activities and total activities rivaling current functional group directed tritium labeling methods. When paired with the appropriate deuterium donor, Cp(PMe(3))Ir(H(3))OTf (4) was found to deuterate a number of organic compounds catalytically.     

The type of group measure space von Neumann algebras

LetG be a countable discrete group acting by measure-preserving automorphisms of a finite measure space (M, ) and let (G,M) be the corresponding group measure space von Neumann algebra, which will be a finite von Neumann algebra. Necessary and sufficient conditions are given for (G,M) to have a non-zero type I part, and the projection on the type I part is explicitly described.This research was supported in part by National Science Foundation Grant MCS 74-19876.     

Preparation of Neutral Ionophores for Alkali and Alkaline Earth Metal Cations and their application in ion selective membrane electrodes

The preparation of a series of non-cyclic, uncharged ligands able to selectively complex alkali and alkaline earth metal cations is described. These molecules are designed to be used as carriers for cations through membranes. Some of the compounds show high Ca²⁺ and Na⁺ selectivity, respectively, in liquid membrane electrodes.