Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement

The Grignard reaction of 2,3-O-isopropylidene-alpha-D-lyxo-pentodialdo-1,4-furanoside and benzylmagnesium chloride (or bromide) afforded a non-separable mixture of diastereomeric benzyl carbinols and diastereomeric o-tolyl carbinols. The latter resulted from an unexpected benzyl to o-tolyl rearrangement. The proportion of benzyl versus o-tolyl derivatives depended on the reaction conditions. Benzylmagnesium chloride afforded predominantly o-tolyl carbinols while the application of benzylmagnesium bromide led preferably to the o-tolyl carbinols only when used in excess or at higher temperatures. The structures of the benzyl and o-tolyl derivatives were confirmed unambiguously by NMR spectral data and X-ray crystallographic analysis of their 5-ketone analogues obtained by oxidation of the corresponding mixture of diastereomeric carbinols. A possible mechanism for the Grignard reaction leading to the benzyl -> o-tolyl rearrangement is also proposed

Consumer Behavior in respect of milk in The Netherlands

In this paper, consumer behaviour in the Netherlands in respect of milk is investigated using a model based on the EKB model, a so-called integrated model of consumer behaviour. The objectives of the study are: to gain insight into the factors that influence buying and consumption behaviour with respect to milk and into the applicability of integrated models to consumer behaviour regarding generic products, such as liquid milk. It was established that liquid milk was perceived as a neutral drink: not ordinary or luxury, as a food not a drink for pleasure, and not as being refreshing. Liquid milk was perceived differently at varying times of consumption during the day. The most important socioeconomic variables explaining individual differences in consumer beliefs regarding milk are: age, level of education, and residential area. These and other conclusions from the analysis are useful for market segmentation. The results suggest that empirical models of the EKB type can contribute to the understanding of consumer behaviour in respect of generic food products. The specific extensions of the general EKB model made in this study may be relevant for the analysis of consumer behaviour in regard to other food products

Analysis of food quality perception processes

A model of the quality perception process of the consumer with respect to food products has been developed. The model integrates a number of quality-related concepts. An empirical study was carried out to examine the relationships between the concepts. It appears that the various concepts can be meaningfully related to the quality perception of different food products. Key words: quality perception, consumer behaviour, food products, agricultural products, quality indicators, quality attributes, quality risk

Resonances in rotationally inelastic scattering of OH(X2ΠX^2\Pi) with helium and neon

We present detailed calculations on resonances in rotationally and spin-orbit inelastic scattering of OH (X\,^2\Pi, j=3/2, F_1, f) radicals with He and Ne atoms. We calculate new \emph{ab initio} potential energy surfaces for OH-He, and the cross sections derived from these surfaces compare favorably with the recent crossed beam scattering experiment of Kirste \emph{et al.} [Phys. Rev. A \textbf{82}, 042717 (2010)]. We identify both shape and Feshbach resonances in the integral and differential state-to-state scattering cross sections, and we discuss the prospects for experimentally observing scattering resonances using Stark decelerated beams of OH radicals.Comment: 14 pages, 15 Figure

Measurement of Length and Position with Frequency Combs

We show two different absolute distance measurement methods with micrometer accuracy based on frequency combs, and we discuss possible applications. Using a mode- locked laser and MEMS-based tracking optics, we measure the 3D position of a retroreflector within 10 ms and with a 24 μm volumetric accuracy. We also investigate modulator-based combs and show that they enable highly sensitive surface topography measurements with microsecond acquisition times and micrometer precision. Moreover, the potential for photonic integration of frequency comb sources is explored

Scattering resonances in slow NH3{}_3-He collisions

We theoretically study slow collisions of NH$_3$ molecules with He atoms, where we focus in particular on the observation of scattering resonances. We calculate state-to-state integral and differential cross sections for collision energies ranging from 10${}^{-4}$ cm$^{-1}$ to 130 cm$^{-1}$, using fully converged quantum close-coupling calculations. To describe the interaction between the NH${}_3$ molecules and the He atoms, we present a four-dimensional potential energy surface, based on an accurate fit of 4180 {\it ab initio} points. Prior to collision, we consider the ammonia molecules to be in their antisymmetric umbrella state with angular momentum $j=1$ and projection $k=1$, which is a suitable state for Stark deceleration. We find pronounced shape and Feshbach resonances, especially for inelastic collisions into the symmetric umbrella state with $j=k=1$. We analyze the observed resonant structures in detail by looking at scattering wavefunctions, phase shifts, and lifetimes. Finally, we discuss the prospects for observing the predicted scattering resonances in future crossed molecular beam experiments with a Stark-decelerated NH$_3$ beam.Comment: 17 pages, 12 figure