Enantioselective Addition of Cyclic Enol Silyl Ethers to 2‐Alkenoyl‐Pyridine‐N‐Oxides Catalysed by CuII–Bis(oxazoline) Complexes

Asymmetric reactions involving (E)‐3‐aryl‐1‐(pyridin‐2‐yl‐N‐oxide)prop‐2‐en‐1‐ones and cyclic enol silyl ethers show good yields and excellent enantioselectivities (up to 99.9 % ee) when catalysed by bis(oxazoline)–Cu^II complexes. Different reaction pathways can be followed by different enol silyl ethers: with 2‐(trimethylsilyloxy)furan, a Mukaiyama–Michael adduct is obtained, whereas a hetero Diels–Alder cycloadduct was formed by using (1,2‐dihydronaphthalen‐4‐yloxy)trimethylsilane. In the latter reaction, the absolute configuration of the product is consistent with a reagent approach to the less hindered Re face of the coordinated substrate in the reactive complex.     

Enantioselective Addition of Cyclic Enol Silyl Ethers to 2-Alkenoyl-Pyridine-N-Oxides Catalysed by Cu(II) -Bis(oxazoline) Complexes

Asymmetric reactions involving (E)-3-aryl-1-(pyridin-2-yl-N-oxide)prop-2-en-1-ones and cyclic enol silyl ethers show good yields and excellent enantioselectivities (up to 99.9?% ee) when catalysed by bis(oxazoline)-Cu(II) complexes. Different reaction pathways can be followed by different enol silyl ethers: with 2-(trimethylsilyloxy)furan, a Mukaiyama-Michael adduct is obtained, whereas a hetero Diels-Alder cycloadduct was formed by using (1,2-dihydronaphthalen-4-yloxy)trimethylsilane. In the latter reaction, the absolute configuration of the product is consistent with a reagent approach to the less hindered Re face of the coordinated substrate in the reactive complex.     

Uncertainty of measurement and conformity assessment: a review

The uncertainty of measurement is the key indicator of the quality of any experimental result. Proper consideration of this uncertainty is imperative when testing a sample against legal/compositional limits. This task can be quite challenging when the entity measured in the investigated sample is so close to the limit that its uncertainty, however estimated, critically affects decision-making. This explains the many literature contributions discussing the problem. Even though some of the most authoritative organisations have issued specific guidelines aimed at assisting the staff involved in such measurements, several aspects of conformity testing are still debated in the literature. In this review, after a short outline of existing information, somewhat more detailed insight is given into the guidelines of ASME, ISO, and Eurachem/CITAC, because they are the most useful tools for operators of testing and calibration laboratories. Some aspects of Council Directive 96/23/EC are also discussed. Insight into the contents of the mentioned documents enables emphasis of analogies and discrepancies.     

Mössbauer studies of phase transformations in iron alloys

Procedures related to the preparation of samples for Mössbauer spectroscopy studies of phase transformations in metals research are discussed in examples of works undertaken by the authors; (i) determination of austempering kinetics of compacted graphite cast irons, (ii) CEMS studies aimed at finding suitable polishing treatments that reproduce the bulk phase proportions, (iii) CEMS investigations on samples polished by spark planing, and (iv) the research of surface processes produced by laser melting treatments.     

Distribution of Mn Atoms in a Substitutional bcc-FeMn Solid Solution

Hyperfine Interactions - We have taken conversion electron Mössbauer spectra to Fe–Mn alloys with 7.5, 10.5 and 13.7 wt.% Mn, that allowed us to obtain the relative fractions of the...     

Preface

Preface

Preface     

Concerning the electroactivity of hydrogen in nitrate melts: A critical discussion in the light of recent hypotheses and suggestions

A critical discussion of the electroactivity of hydrogen in nitrate melts is reported. The consistency of recent alternative models, proposed by other authors, to explain our experimental results has been tested by additional experiments, in part suggested by those authors themselves. Our mechanistic model seems, at present, the only consistent way to interpret the whole of the phenomena related to the known hydrogen systems in nitrate melts.     

Monte Carlo Simulations of Mössbauer Results in Fe–C Austenite

The Mössbauer signal of Fe–C austenite is difficult to interpret because different Fe–C configurations give rise to different hyperfine interactions. Two competing models for the distribution of carbon atoms in the fcc austenite lattice have been proposed to account for Mössbauer spectra. Both models assume a repulsive C–C interaction of different magnitude and different Fe–C configurations. From the Mössbauer spectra, the abundance of the different iron sites could be determined. That abundance may also be calculated with Monte Carlo simulations. In this work, using the two controversial models, we compare the relative fractions of the Fe–C configurations obtained from Mössbauer spectra of vermicular austempered cast iron with Monte Carlo simulation.