Carbohydrate-derived iminium salt organocatalysts for the asymmetric epoxidation of alkenes

A new family of carbohydrate-based dihydroisoquinolinium salts has been prepared and tested for potential as asymmetric catalysts for the epoxidation of unfunctionalized alkene substrates, providing up to 57% ee in the product epoxides

Modeling what we sample and sampling what we model: challenges for zooplankton model assessment

Zooplankton are the intermediate trophic level between phytoplankton and fish, and are an important component of carbon and nutrient cycles, accounting for a large proportion of the energy transfer to pelagic fishes and the deep ocean. Given zooplankton's importance, models need to adequately represent zooplankton dynamics. A major obstacle, though, is the lack of model assessment. Here we try and stimulate the assessment of zooplankton in models by filling three gaps. The first is that many zooplankton observationalists are unfamiliar with the biogeochemical, ecosystem, size-based and individual-based models that have zooplankton functional groups, so we describe their primary uses and how each typically represents zooplankton. The second gap is that many modelers are unaware of the zooplankton data that are available, and are unaccustomed to the different zooplankton sampling systems, so we describe the main sampling platforms and discuss their strengths and weaknesses for model assessment. Filling these gaps in our understanding of models and observations provides the necessary context to address the last gap—a blueprint for model assessment of zooplankton. We detail two ways that zooplankton biomass/abundance observations can be used to assess models: data wrangling that transforms observations to be more similar to model output; and observation models that transform model outputs to be more like observations. We hope that this review will encourage greater assessment of zooplankton in models and ultimately improve the representation of their dynamics

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

The belief in a just world and distress at school

This article investigates the relationship between the belief in a just world (BJW) and distress at school. On the basis of just world theory, the authors argue that strong student BJW should be associated with low school distress. Two questionnaire studies with German secondary school students attending grades 7–13 are reported. Both studies found strong BJW to be associated with less distress at school, better grades, and the evaluation of grades and teachers as more just. Moreover, the relationship between strong BJW and low school distress persisted when controlled for grades, justice of grades, and teacher justice. This relationship held for all students, independently of their school track, grade level, or gender. Overall, the pattern of results reveals school distress to have a unique association with BJW and school-specific justice cognitions

Novel biphenyl organocatalysts for iminium ion-catalyzed asymmetric epoxidation

Two novel chiral biphenyl iminium salts derived from l-acetonamine, containing electron-withdrawing 3,3'-substituents on the biphenyl unit, have been prepared and tested as asymmetric catalysts for epoxidation of prochiral alkenes. The results are compared with those achieved using the corresponding unsubstituted system

Facile asymmetric construction of a functionalized dodecahydrobenz[a]indolo[3,2-h]quinolizine template

We report a highly diastereoselective approach for the synthesis of a functionalized dodecahydrobenz[a]indolo[3,2-h]quinolizine ring system that is present as the heterocyclic core of the manadomanzamine alkaloids. We have achieved complete control over the relative and absolute stereochemistries at the three contiguous stereocentres at ring positions 1, 10 and 24 in only two linear synthetic steps. The introduction of useful functionality to the heterocyclic skeleton is significant as this may allow for future derivatization, and application of this route in an asymmetric synthesis of the manadomanzamine natural products