Photoactivated 1,3-dipolar cycloaddition for the rapid preparation of F labelled radiotracers

An ¹⁸F-labelled 2,5-diaryl tetrazole reagent has been prepared and reacted with substituted alkene dipolarophiles through a photoactivated 1,3-dipolar cycloaddition reaction. The radiobioconjugation reaction furnished the desired product in 5 min with radiochemical conversions of 85-95% at room temperature. Remarkably, for the activated dipolarophiles, these results were obtained in highly dilute solutions (10-100 μM).     

A short proof of a characterization of reflexivity of James

A short direct proof is given to a well-known intrinsic characterization of reflexivity due to R. C. James.

     

Adiabatic 1H decoupling scheme for very accurate intensity measurements in 13C NMR

Adiabatic proton decoupling has been optimized in order to obtain accurate quantitative measurements of intensities on 13C NMR spectra. For each offset, the minimum adiabaticity factor (Km) reached during the pulse was computed. This K(m) profile was used to optimize the peak value and the swept frequency range of the adiabatic pulses. With a cosinus amplitude modulation, offset-independent-adiabaticity, and the M4P5-M4P9-M4P5'-M4P9' phase cycle, an accuracy of 2 per thousand for the 13C NMR measurements was reached. An approach using bi-labeled 13C acetic acid and ethanol at 99% allowed a fine experimental determination of the uniformity of the decoupling profile. The comparison with WALTZ-16 highlights the improvements in the uniformity of the proton decoupling.     

Enantioselective oxidation of O-methyl-N-hydroxylamines using monoamine oxidase N as catalyst

Enantioselective oxidation of racemic O-methyl-N-hydroxycyclohexylethylamine, using a variant of monoamine oxidase N (MAO-N) from Aspergillus niger, yields unreacted (R)-enantiomer (e.e. = 99%) together with the oxime exclusively in the (E)-configuration.     

The strong approximation property

We introduce and investigate the strong approximation property of Banach spaces which is strictly stronger than the approximation property and at least formally weaker than the weak bounded approximation property. Among others, we show that the weak bounded approximation property is equivalent to a quantitative strengthening of the strong approximation property. Some recent results on the approximation property of Banach spaces and their dual spaces are improved.     

Wounding-Induced VOC Emissions in Five Tropical Agricultural Species

Leaf mechanical wounding triggers a rapid release—within minutes—of a blend of volatile organic compounds. A wounding-induced VOC blend is mainly composed of oxygenated ubiquitous stress volatiles such as methanol and volatile products of lipoxygenase (LOX) pathway (mainly C5 and C6 alcohols and aldehydes and their derivatives), but also includes multiple minor VOCs that collectively act as infochemicals, inducing defences in non-damaged plant leaves and neighbouring plants and attracting herbivore enemies. At present, the interspecific variability of the rate of induction and magnitude of wounding-induced emissions and the extent to which plant structural traits and physiological activity alter these emissions are poorly known. Particularly scarce is information on the induced emissions in tropical agricultural plant species, despite their economic importance and large area of cultivation at regional and global scales. We chose five tropical crops with varying photosynthetic activity and leaf structural characteristics—Abelmoschus esculentus, Amaranthus cruentus, Amaranthus hybridus, Solanum aethiopicum, and Telfairia occidentalis—to characterize the kinetics and magnitude of wounding-induced emissions, hypothesizing that the induced emission response is greater and faster in physiologically more active species with greater photosynthetic activity than in less active species. Rapid highly repeatable leaf wounds (12 mm cuts) were generated by a within-leaf-chamber cutting knife. Wounding-induced VOC emissions were measured continuously with a proton-transfer reaction time-of-flight mass spectrometer and gas-chromatography mass spectrometry was used to separate isomers. Twenty-three ion VOCs and twelve terpenoid molecule structures were identified, whereas ubiquitous stress volatiles methanol (on average 40% of total emissions), hexenal (24%), and acetaldehyde (11%) were the main compounds across the species. Emissions of low-weight oxygenated compounds (LOC, 70% of total) and LOX products (29%) were positively correlated across species, but minor VOC components, monoterpenoids and benzenoids, were negatively correlated with LOC and LOX, indicating a reverse relationship between signal specificity and strength. There was a large interspecific variability in the rate of induction and emission magnitude, but the hypothesis of a stronger emission response in physiologically more active species was only partly supported. In addition, the overall emission levels were somewhat lower with different emission blend compared to the data reported for wild species, as well as different shares for the VOCs in the blend. The study demonstrates that wounding-dependent emissions from tropical agricultural crops can significantly contribute to atmospheric volatiles, and these emissions cannot be predicted based on current evidence of wild plant model systems.     

A framework for the value of information in inventory replenishment

Technological advances and changes in supply chain management practices have combined to draw attention to the value of information sharing in inventory replenishment. Academic research has produced seemingly conflicting results due to differences in the type of information that is shared, the supply chain structure, and the selection and parameterization of performance goals. This research provides a framework to help explain apparent differences in the extant literature. Our purpose is to understand what determines the value of information. With this specific view, we establish a set of research questions and suggest directions for future research.