Tandem Baeyer–Villiger/Wittig/oxa-Michael addition: One-step to 5-substituted γ-lactones

The results reported in this study provide a practical protocol for the construction, in one single step of synthetically important γ-lactones in good yields starting from α-hydroxy cyclobutanone, H2O2 and several stabilized phosphonium ylides. Our synthetic strategy relies on a tandem Baeyer–Villiger oxidation/Wittig reaction/oxa-Michael addition

Growth of monolayer graphene on 8deg off-axis 4H-SiC (000-1) substrates with application to quantum transport devices

Using high temperature annealing conditions with a graphite cap covering the C-face of an 8deg off-axis 4H-SiC sample, large and homogeneous single epitaxial graphene layers have been grown. Raman spectroscopy shows evidence of the almost free-standing character of these monolayer graphene sheets, which was confirmed by magneto-transport measurements. We find a moderate p-type doping, high carrier mobility and half integer Quantum Hall effect typical of high quality graphene samples. This opens the way to a fully compatible integration of graphene with SiC devices on the wafers that constitute the standard in today's SiC industry.Comment: 11 pages, 4 figures , Submitted in AP

Metabolomics and lipid profile analysis of Coccomyxa melkonianii SCCA 048

With an unsupervised GC–MS metabolomics approach, polar metabolite changes of the microalgae Coccomyxa melkonianii SCCA 048 grown under standard conditions for seven weeks were studied. C. melkonianii was sampled at the Rio Irvi River, in the mining site of Montevecchio-Ingurtosu (Sardinia, Italy), which is severely contaminated by heavy metals and shows high concentrations of sulfates. The partial-least-square (PLS) analysis of the GC–MS data indicated that growth of C. melkonianii was characterized by an increase of the levels of threonic acid, myo-inositol, malic acid, and fumaric acid. Furthermore, at the sixth week of exponential phase the lipid fingerprint of C. melkonianii was studied by LC-QTOF-MS. C. melkonianii lipid extract characterized through an iterative MS/MS analysis showed the following percent levels: 61.34 ± 0.60% for triacylglycerols (TAG); 11.55 ± 0.09% for diacylglyceryltrimethyl homoserines (DGTS), 11.34 ± 0.10% for sulfoquinovosyldiacylglycerols (SQDG) and, 5.29 ± 0.04% for lysodiacylglyceryltrimethyl homoserines (LDGTS). Noteworthy, we were able to annotate different fatty acid ester of hydroxyl fatty acid, such as FAHFA (18:1_20:3), FAHFA (18:2_20:4), FAHFA (18:0_20:2), and FAHFA (18:1_18:0), with relevant biological activity. These approaches can be useful to study the biochemistry of this extremophile algae in the view of its potential exploitation in the phycoremediation of polluted mining areas

Mechanochemistry Frees Thiourea Dioxide (TDO) from the ‘Veils’ of Solvent, Exposing All Its Reactivity

The synthesis of nitrogen-based heterocycles has always been considered essential in developing pharmaceuticals in medicine and agriculture. This explains why various synthetic approaches have been proposed in recent decades. However performing as methods, they often imply harsh conditions or the employment of toxic solvents and dangerous reagents. Mechanochemistry is undoubtedly one of the most promising technologies currently used for reducing any possible environmental impact, addressing the worldwide interest in counteracting environmental pollution. Following this line, we propose a new mechanochemical protocol for synthesizing various heterocyclic classes by exploiting thiourea dioxide (TDO)'s reducing proprieties and electrophilic nature. Simultaneously exploiting the low cost of a component of the textile industry such as TDO and all the advantages brought by a green technique such as mechanochemistry, we plot a route towards a more sustainable and eco-friendly methodology for preparing heterocyclic moieties

Aerodynamic analysis of Ampyx’s airborne wind energy system

Besides classical horizontal and vertical axis wind turbines, alternative ways to harvest wind energy are currently being explored. One promising concept is represented by airborne wind energy systems. Different airborne wind energy concepts have been ideated and investigated over the past few decades. The work reported here focuses on the concept being developed by Ampyx Power that basically generates power using a tethered airplane which drives a generator on the ground. The aim of the work reported here is to develop and compare design calculations for such a power plane. In this study a comparison was made between steady and unsteady RANS CFD calculations from SU2 and OpenFOAM. Subsequently, using the data from the CFD calculation two different power prediction models were developed and compared, one using 2D CFD data with the free vortex code AWSM and the other using the same data with a nonlinear lifting line approach to model the power plane in its figure eight flying trajectory. Overall, comparisons show that for all practical angles of attack, as well as a range of flap angles, that 2D CFD results agree extremely well between both solvers. The 3D CFD results show <20% differences on the computed total forces, despite achieving good agreement on the relative force contributions across the power plane. A very good agreement has also been established between the power prediction models

New diagnostic possibilities in systemic neonatal infections: metabolomics

Systemic neonatal infection is a serious complication in preterm and term infants and is defined as a complex clinical syndrome caused by bacteria, fungi and virus. Sepsis remains among the leading causes of death in both developed and underdeveloped countries above all in the neonatal period. Earlier diagnosis may offer the ability to initiate treatment to prevent adverse outcomes. There have been many studies on various diagnostic haematological markers like acute phase reactants, C-reactive protein, procalcitonin, interleukins and presepsin. However, there is still no single test that satisfies the criteria as being the ideal marker for the early diagnosis of neonatal sepsis. In this regard, metabolomic analysis seems to be a promising method for determining metabolic variations correlated with systemic neonatal infection

Solvent-Free Synthesis of Quaternary Oxazolidine-2-thione β3-Amino Ester Analogs

A solvent-free organocatalyzed intermolecular cyclization reaction starting from β-substituted γ-hydroxy-α,β-unsaturated esters and aryl isothiocyanates proceeds via an aza-Michael addition to provide previously unknown quaternary oxazolidine-2-thione β3 amino ester analogs. A panel of diversely-substituted esters was investigated, including β,γ-disubstituted examples which provided the target molecules with very high cis diastereoselectivity