Preparation of unsymmetrical ketones from tosylhydrazones and aromatic aldehydes via formyl C–H bond insertion

Preparation of ketones by insertion of diazo compounds into the formyl C−H bond of an aldehyde is an attractive procedure, but use of structurally diverse diazo compounds is hampered by preparation and safety issues. A convenient procedure for the synthesis of unsymmetrical ketones from bench-stable tosylhydrazones and aryl aldehydes is reported. The procedure can be performed in one pot from the parent carbonyl compound and needs only a base, with no additional promoters being required

Interest of Raman spectroscopy for the study of dental material: The zirconia material example

2 - RevueThe mechanical properties, the biocompatibility and the aesthetic aspect make of zirconia a material of interest for orthopaedics and dental prosthetics. This ceramic presents a transformation of phase ability, which is responsible for its high mechanical resistance and fracture toughness. In biomedical applications, tetragonal metastable zirconia is used. Under mechanical stresses, zirconia grains experience a transformation towards a monoclinic structure. This phenomenon exists also under hydrothermal stresses and is known as low temperature degradation, it is well described for yttria partially stabilised zirconia, 3Y-TZP. Kinetics of transformation is usually studied using X-ray diffraction or AFM. The aim of this article is to present Raman spectroscopy as an alternative and non-destructive method to study the transformation of zirconia. After a presentation of Raman scattering, examples of tetragonal, cubic and monoclinic zirconia Raman spectra are presented. The calibration procedure to assess the penetration of the laser probe in the material is detailed and found to reach 70 [mu]m. The quantitative measurement of monoclinic zirconia volume is explained. An example illustrates the decrease of the transformation from 12 at the material subsurface to 2% in a 70 [mu]m depth

Commercial Reformulation: An Economic and Environmentally Neutral Means of Managing Explosives and Solid Propellants

The reformulation of military explosives and solid propellants into commercial explosives offers a unique solution to the problem of disposing of high energy materials with essentially zero environmental impact at a low cost and with a salable product. Studies using the insensitive PBX, PBXN-4 have been completed through the pilot plant stage and have been successfully tested as a mining explosive. A number of other military explosives have been examined and their VOD\u27s (velocity on detonation) and heats of explosions determined and in some instances tested in \u27field\u27 operations. The equipment and unit operations required for reformulation are simple and inexpensive. The total market potential is far larger than the available supply of PBX\u27s and other military explosives. The extension of the reformulation approach to 1.1 solid rocket propellants is in progress. Initial studies indicate that the method is viable. The quantities involved have the potential of impacting less than 1% of the very large US explosives market. The products available from reformulation are in part a function of the means of removal of the 1.1 propellants from the cases. With dry methods, a range of products from \u27super\u27 blasting gelatins to materials comparable to ANFO are available in the form of dry or slurried explosives. With wet methods, the range is narrower with VOD\u27s of approximately 4 km/sec and heats of explosion of approximately 1000 cal/g at a density of 1.25 g/cc being easily attainable in the form of slurries. With both HE and 1.1 propellant streams it is possible to tailor the power of the resultant explosives to reach a desired set of properties. This permits the handling of a variable stream of redundant materials and the furnishing of a \u27constant\u27 product to the customer. The technology involved has essentially no waste stream and very closely meets the goals of the US Resource Conservation and Recovery Act (RCRA)

Script concordance tests: A call for action in dental education

The Script Concordance Test (SCT) is an educational tool that aims to assess the ability to interpret medical information under conditions of uncertainty. It is widely used and validated in health education, but almost unknown in dentistry. Based on authentic clinical problem-solving situations, it allows to assess clinical reasoning that experienced health workers develop over the years. A specific scoring system, dedicated to SCT, considers the variability of responses of practitioners in the same clinical situations. Finally, the scores generated by SCT reflect the respondents? ability to interpret clinical data compared to experienced clinicians. This article aims to familiarise the dental educators? community with SCT construction, optimisation and its possible applications.Scopu

Corrigendum to “Clinical Behavior of Second-Generation Zirconia Monolithic Posterior Restorations: Two-year Results of a Prospective Study with Ex Vivo Analyses including Patients with Clinical Signs of Bruxism” [J. Dent. 91 (2019) 103229] (Journal of Dentistry (2019) 91, (S0300571219302313), (10.1016/j.jdent.2019.103229))

peer reviewedThe authors regret that a mistake occurred in the abstract of the article. In the following sentence: "Monolithic zirconia FPDs are promising but the failure rate of single-unit restorations was not as high as expected in this sample including patients with bruxism clinical signs", “failure” needs to be replaced by “success”. The authors would like to apologise for any inconvenience caused