The carrageenan from Iridaea undulosa B.; Analysis,fractionation and alkaline treatment

The carrageenan extracted from the seaweed Iridaea undulosa is devoid of a k-fraction and is composed of major amounts of ‘intermediate fractions’ (fractions which precipitate at potassium chloride concentrations higher than 0.125M) and lesser amounts of a ‘soluble fraction’ (soluble in 2.0M potassium chloride). It did not form gels in water or milk. The preparative fractionation of the carrageenan gave eight fractions which precipitated in narrow ranges of potassium chloride concentrations and on ultracentrifugation showed only one sharp peak. Analysis of these fractions, their infrared spectra, and the results of the periodate oxidation analysis permitted the identification of some structural units and suggested others. The alkaline treatment of the carrageenan gave a product comprising a k-fraction and a soluble fraction. The k-fraction, obtained with a high yield (53.6% of the modified polysaccharide), is capable of gelling.     

Combined atomic-scale modelling and experimental studies of nucleation in the solid state

The process of solid-state nucleation in highly supersaturated solid solutions has been investigated on the atomic scale by a combination of three-dimensional atom probe analysis and atomistic modelling using dynamical Ising models. In binary Cu-Co alloys, a simple atom-exchange model with a single thermodynamic parameter derived from phase-diagram data was able to reproduce the atomic-scale microstructures observed in the atom probe, and also match the measured peak precipitate density. Modelling solute effects in complex copper-bearing steels required a more sophisticated model based on a vacancy-hopping mechanism and a larger number of thermodynamic and kinetic parameters derived from independent experimental data and theoretical calculations. The model gave an excellent match to the experimentally observed microstructures, and it reproduced features such as the clustering of Ni and Mn before the precipitation of Cu. The model also allowed time-dependent behaviour to be investigated, and it showed that solute clustering of Ni and Mn occurs during the cooling of the alloy. These clusters then act as heterogeneous nucleation sites for the formation of copper precipitates. Understanding such complex solute interaction effects through combined experiment and modelling is an essential step to controlling nucleation and hence the fine-scale microstructures in advanced engineering alloys.     

Stabilisation of state‐and‐input constrained nonlinear systems via diffeomorphisms: A Sontag's formula approach with an actual application

In this work, we provide a new and constructive outlook for the control of state‐and‐input constrained nonlinear systems. Previously, explicit solutions have been mainly focused on the finding of a barrier‐like Lyapunov function, whereas we propose the construction of a diffeomorphism to map all the trajectories of the constrained dynamics into an unconstrained one. Careful analysis has revealed that only some foundations of differential geometry and a technical assumption are necessary to construct the proposed methodology based on the well‐established theories of control Lyapunov functions and Sontag's universal formulae. Altogether, it allows us to obtain an explicit solution that even includes bounded constraints in the control action, giving the designer a way to decide (to some extent) the trade‐off between control saturations and robustness. Moreover, this approach does not rely on the own structure of the system dynamics, therefore covering a broad class of nonlinear systems. The main advantage of this approach is that the use of a diffeomorphism allows the splitting of the mathematical treatment of the constraint and the Lyapunov controller design. The result has been successfully applied to solve the dynamic positioning of an actual ship, where the nonlinear state constraints describe a strait. This approach enabled us to design a control Lyapunov function and thereby use Sontag's formula to solve the stabilisation problem. Realistic simulations have been executed in a real scenario on the simulator owned by an international shipbuilding company.     

Adjustments of Microwave-Based Measurements on Coal Moisture Using Natural Radioactivity Techniques

The use of nonconventional on-line measurements of moisture and ash content in coal is presented. The background research is briefly reviewed. The possibilities of adjusting microwave-based moisture measurements using natural radioactive techniques, and vice versa, are proposed. The results obtained from the simultaneous analysis of moisture and ash content as well as the correlation improvements are shown.     

First report on the presence of emerging Fusarium mycotoxins enniatins (A,A1, B,B1), beauvericin and fusaproliferin in rice on the Moroccan retail markets

Seventy samples of rice purchased from local markets in six cities from Morocco (Rabat, Casablanca, Kénitra, Mohammadia, Tanger and Errachidia) were analyzed for the presence of six emerging mycotoxins: four enniatins ENs (ENA, ENA₁, ENB and ENB₁), beauvericin (BEA) and fusaproliferin (FUS). Samples were extracted with a mixture of acetonitrile/water (85/15, v/v) by using an ultra-turrax homogenizer. Mycotoxins were then identified and quantified with liquid chromatography (LC) coupled to diode array detector (DAD). Positive samples were confirmed with an LC-MS/MS. Analytical results showed that BEA was present in 75.7% of total analyzed samples. BEA levels varied between 3.8 and 26.3 mg/kg. The frequencies of contamination of samples with total ENs and FUS were 50% and 4.3%, respectively. Among the ENs, ENB was the mycotoxin much more found (30% of total samples), while ENB₁, ENA and ENA₁ were found in 24.6%, 22.8% and 5.7% of total samples, respectively. The high ENs value was registered in a rice sample from kénitra (448.7 mg/kg of ENA₁). This is the first study that describes the presence of emerging Fusarium mycotoxins in rice available in Morocco.     

Statistical analysis of atom probe data: Detecting the early stages of solute clustering and/or co-segregation

Statistical analysis of atom probe data has improved dramatically in the last decade and it is now possible to determine the size, the number density and the composition of individual clusters or precipitates such as those formed in reactor pressure vessel (RPV) steels during irradiation. However, the characterisation of the onset of clustering or co-segregation is more difficult and has traditionally focused on the use of composition frequency distributions (for detecting clustering) and contingency tables (for detecting co-segregation).     

A general method for evaluating the overhead when consolidating servers: performance degradation in virtual machines and containers

The Journal of Supercomputing - Server consolidation is one of the most commonly used techniques for reducing energy consumption in datacenters; however, this results in inherent performance...     

Low rate error modeling of articulated heavy vehicle dynamics and experimental validation

International Journal of Control, Automation and Systems - In the automotive domain, adequate control and diagnosis rely on the use of state observers and parametric identification systems to...     

Electroreduction of quinones under aprotic conditions

The electrochemical reduction of a series of quinones in DMF, acetonitrile and 1,2-dichloroethane under controlled potential conditions and in the presence/absence of benzene diazonium tetrafluoroborate, is presented. It provides an interesting entry to new hydroxycarboxamides, dioxins, cyanomethylated derivatives, and other useful compounds. The electrochemical behaviour of these systems and mechanistic proposals are given.