Nuclear Magnetic Resonance Spectroscopy. Structure and Dynamic Character of Allylic Grignard Reagents

Studies have been made of the nuclear magnetic resonance spectra of several allylic Grignard reagents. The Grignard reagent prepared from γ,γ-dimethylallyl bromide appears best formulated as an equilibrium mixture of γ,γ-dimethylallylmagnesium bromide and α,α-dimethylallylmagnesium bromide, in which the former is the major component. The rate of interconversion of the allylic isomers is rapid on the n.m.r. time scale at room temperature, but slow at -40°

Nuclear Magnetic Resonance Spectra. Allylmagnesium Bromide

The proton nuclear magnetic resonance (n.m.r.) spectrum of allylmagnesium bromide (I, Fig. 1) Fig. 1.-Proton magnetic resonance spectra of allylmagnesium bromide in diethyl ether solution (upper) and allylbenzene (lower). The spectra were taken with a Varian Associates High Resolution Spectrometer (V-4300) at 60 Mc. with a 12-inch magnet equipped with a Super-stabilizer. Chemical shifts are in C.P.S. from benzene (external reference) and were measured by the audio-oscillator sideband superposition method. The signals designated C_6H_(10) in the allylmagnesium bromide spectrum are due to diallyl formed by coupling during preparation of the Grignard reagent, as verified by the spectrum of a sample to which diallyl had been added deliberately

A pattern based, robust approach to cyclic master surgery scheduling

The Master Surgery Scheduling problem consists of finding a suitable allocation of operating resources to surgical groups. A myriad of variants of the problem has been addressed in literature. Here we focus on two major variants, arising during a cooperation with Sykehuset Asker og B'rum HF, a large hospital in the city of Oslo. The first variant asks for balancing patient queue lengths among different specialties, whereas the second for minimizing resort to overtime. To cope with these problems we introduce a new mixed integer linear formulation and show its beneficial properties. Both problems require the estimation of demand levels. As such estimation is affected by uncertainty, we also develop a light robustness approach to the second variant. Finally we present computational results on a number of real-world instances provided by our reference hospital

Maintaining Constraint-based Applications

Many knowledge-based applications require knowledge maintenance to keep the application functional throughout its lifecycle. In this paper we present iCAM, a constraintbased knowledge maintenance system that operates in a hospital’s material management domain. iCAM uses consistency algorithms to assist users in placing orders and making order corrections, and to ensure that maintenance activities are consistent with the department’s ordering environment. This approach allows iCAM to interact with the user to revise orders and/or to update the knowledge base. For the user, there is not much distinction between these two tasks. This is one of iCAM’s greatest strengths; order corrections and knowledge maintenance are carried out in a similar manner, since both are based on inconsistencies with respect to the existing knowledge base. iCAM has various constraint types that support physical and policy restrictions. It also allows maintenance to be done by a number of users while maintaining the integrity of the knowledge base by a system of role restrictions

Nuclear Magnetic Resonance Spectroscopy. γ,γ-Dimethylallylmagnesium Bromide

The nuclear magnetic resonance (n.m.r.) spectrum of allylmagnesium bromide is characterized by a simplicity inconsistent with any single classical structure; notably, the α and γ protons occupy magnetically equivalent positions

Nuclear Magnetic Resonance Spectroscopy. The Structure of Butenylmagnesium Bromide

Crotyl bromide and α-methylallyl bromide each react with magnesium in ether to yield the same butenyl Grignard reagent, which conceivably could be crotylmagnesium bromide (I), α-methylallyl-magnesium bromide (II), a more or less mobile equilibrium mixture of I and II, or an intermediate, bridged structure such as III

Small-Ring Compounds. XXVIII. Isotope-Position Rearrangements of Allylcarbinyl Grignard Reagents

We have observed a remarkable rearrangement while attempting to prepare 4-penten-2-ylarnine (I) through the reaction of the Grignard reagent derived from 4-penten-2-yl chloride (II) with methoxylamine, in that part of the amine formed appeared to be 2-methyl-3-butenylamine (III)

Photoluminescence of Gold Nanorods: Purcell Effect Enhanced Emission from Hot Carriers

We demonstrate, experimentally and theoretically, that the photon emission from gold nanorods can be viewed as a Purcell effect enhanced radiative recombination of hot carriers. By correlating the single-particle photoluminescence spectra and quantum yields of gold nanorods measured for five different excitation wavelengths and varied excitation powers, we illustrate the effects of hot carrier distributions evolving through interband and intraband transitions and the photonic density of states on the nanorod photoluminescence. Our model, using only one fixed input parameter, describes quantitatively both emission from interband recombination and the main photoluminescence peak coinciding with the longitudinal surface plasmon resonance