Controlled radical polymerization of N,N-dimethylaminoethyl methacrylate using triazolinyl as counter radical

Summary The role of the triazolinyl radical as additive for controlled radical polymerisation is investigated for N,N-dimethylaminoethyl methacrylate (DMAEMA) as polar monomer. A linear increase of the molecular weight with conversion and first-order kinetics are observed proving the controlled behaviour of the polymerization. The end-functionalisation of the obtained polymers was proven by both GPC und UV-spectroscopy. Furthermore, various amphiphilic block copolymers were obtained by chain extension with styrene, methyl methacrylate and ethyl methacrylate. In all cases monomodal GPC curves were obtained indicating an almost quantitative reinitiation.     

On the electronic nature of silicon and germanium based oxynitrides and their related mechanical,optical and vibrational properties as obtained from DFT and DFPT

Electronic structure, bonding and optical properties of the orthorhombic oxynitrides Si₂N₂O and Ge₂N₂O are studied using the density function theory as implemented in pseudo-potential plane wave and full-potential (linearized) augmented plane wave plus local orbitals methods. Generalized gradient approximation is employed in order to determine the band gap energy. Indeed, the Si₂N₂O exhibits a large direct gap whereas Ge₂N₂O have an indirect one. Bonding is analyzed via the charge densities and Mulliken population, where the role of oxygen is investigated. The analysis of the elastic constants show the mechanical stability of both oxynitrides. Their bulk and shear modulus are slightly smaller than those reported on nitrides semiconductors due to the oxygen presence. The optical properties, namely the dielectric function, optical reflectivity, refractive index and electron energy loss, are reported for radiation up to 30 eV. The phonon dispersion relation, zone-center optical mode frequency, density of phonon states are calculated using the density functional perturbed theory. Thermodynamic properties of Si₂N₂O and Ge₂N₂O, such as heat capacity and Debye temperature, are given for reference. Our study suggests that Si₂N₂O and Ge₂N₂O could be a promising potential materials for applications in the microelectronics and optoelectronics areas of research.     

X-Ray Diffraction and Mössbauer Studies of Nanostructured Ni40Fe60 Powder: Structure Defects and Hyperfine Structure

Journal of Superconductivity and Novel Magnetism - A nanostructured nickel–iron alloy having the Ni40Fe60 composition was prepared through the mechanical alloying of the elemental powders in...     

Salt effect on phenolics and antioxidant activities of Tunisian and Canadian sweet marjoram (Origanum majorana L.) shoots

BACKGROUND: Two varieties of Origanum majorana (Canadian and Tunisian) were evaluated for their phenolic, flavonoid and tannin contents, individual phenolic compounds and antioxidant activities under NaCl constraint. RESULTS: The results showed a significant variability in phenolic composition and antioxidant behavior between the two varieties under salt stress. The phenolic composition of methanolic extracts was determined by reversed‐phase high‐performance liquid chromatography. Amentoflavone was the predominant flavonoid compound; in addition, trans‐2‐hydrocinnamic acid became the major phenolic acid with salt treatment of the Tunisian variety. In the control, Canadian variety extract was characterized by high levels of gallic acid and amentoflavone. However, under 75 mmol L^?1 NaCl, gallic acid content doubled, whereas amentoflavone content was maintained in the Canadian variety. Stimulation of phenolic acid biosynthesis was observed in these two varieties under salt treatment despite the fact that shoots of the Tunisian variety showed higher antioxidant activities compared to those from the Canadian variety. Tunisian O. majorana might have developed tolerance to salinity and avoided tissue damage by activating enzymes involved in the galactosylation of quercetin into quercetin‐3‐galactoside and quercetin‐3‐rhamnoside. CONCLUSION: Our results confirmed the tolerance of Tunisian O. majorana plants. Copyright © 2012 Society of Chemical Industry     

Application of geothermal energy for heating and fresh water production in a brackish water greenhouse desalination unit: A case study from Algeria

The aim of this paper was to outline a proposed a new brackish water greenhouse desalination unit powered by geothermal energy for the development of arid and relatively cold regions, using Algeria as a case study. Countries which have abundant sea/brackish water resources and good geothermal conditions are ideal candidates for producing fresh water from sea/brackish water. The establishment of human habitats in these arid areas strongly depends on availability of fresh water. The main advantage of using geothermal energy to power brackish water greenhouse desalination units is that this renewable energy source can provide power 24 h a day. This resource is generally invariant with less intermittence problems compared to other renewable resources such as solar or wind energy. Geothermal resources can both be used to heat the greenhouses and to provide fresh water needed for irrigation of the crops cultivated inside the greenhouses. A review of the geothermal potential in the case study country is also outlined.     

Model predictive control for continuous lactide ring‐opening polymerization processes

Polylactic acid (PLA) is an attractive environment‐friendly thermoplastic that is bio‐sourced and biodegradable. PLA is industrially produced by the ring‐opening polymerization of lactide. This reaction is sensitive to drifts in the operating conditions and impurities in the raw materials that may affect the reaction rate as well as the polymer properties, which can be very costly in continuous processes. It is therefore crucial to employ a control strategy that allows recovering the nominal conditions and maintaining the desired properties and conversion level in case of drift. Three control strategies are discussed in this paper: proportional‐integral (PI) controller, dynamic optimization, and model predictive control (MPC). The proposed approaches are validated by simulation of a continuous PLA process constituted of three cascade reactors including one loop reactor in the middle. Besides the coupling of inputs and outputs, the process model is highly nonlinear, and the control is done only on the boundaries. The results show that the open‐loop optimization strategy provides better performance compared to the PI controller if the disturbance is assumed to be measured. The MPC also shows superior performances provided that the disturbance is first estimated. A polynomial model is developed to predict the nonmeasured disturbance based on the measured outputs.     

Leveraging multiuser diversity for adaptive hybrid satellite‐LTE downlink scheduler (H‐MUDoS) in emerging 5G‐satellite network

In order to achieve ubiquitous coverage and service continuity in future 5G network, satellite‐based access is the best solution to complement the terrestrial LTE‐A. In light of this, we introduce a channel‐aware hybrid scheduling technique on the basis of satellite‐LTE spectrum sharing. According to the user‐experienced channel, base stations (eNodeB) and the satellite will work cooperatively. The eNodeB mainly provides service in urban area for high density population. Meanwhile, the satellite will perform either offloading, providing service for under‐served users, or extra coverage for users in rural and remote areas having no coverage of eNodeB. Leveraging the multiuser diversity, we implement a new metrics computation method for hybrid satellite‐LTE downlink scheduler (H‐MUDoS). Compared with other existing schedulers, simulation results clearly demonstrate the high performance of H‐MUDoS in terms of spectral efficiency in addition to improvement of the quality‐of‐service requirements and capacity maximization.     

A generic tool to federate WAN servers

On a Wide Area Network (WAN), services are more efficient if they are supported by several servers located near their respective clients. In this article, we present a generic tool which facilitates the federation of servers over a WAN. This tool is in charge of both dynamically managing the federation and propagating requests to all the federation’s servers. It may be applied to any kind of widely available service. As far as we know, there is no generic tool that can be used by WAN services to federate their servers. We present the benefits these services could derive from our federation tool. The federation adapts dynamically in case of server addition, server failure and network topology modification. Each server has a global view of the federation which is used especially to propagate requests to the federation. We present the general model and the design of the tool. The tool is built upon group communication objects. And we present some implementation issues in a CORBA (Common Object Request Broker Architecture) environment. The tool is generic in that it may be applied to any service. In this paper we show how a specific service may use the generic federation tool especially to propagate typed requests. Finally, we present an application of this tool for federating CORBA traders.     

Direct observation of the surface structure of French fries by UV–VIS confocal laser scanning microscopy

Observations of raw, fried and air-dried potato parenchyma samples were made with a UV–VIS confocal laser scanning microscope in reflective and fluorescence modes. Distinction between oil and cells was made possible by the addition of a fluorescent probe in the frying oil and the use of the natural fluorescence of cells. Observations were recorded at different depths and were treated to make volumetric reconstructions at different product scales. The results showed that after frying, the cellular structures were well conserved in terms of shape and size. Oil was shown to be mainly located in the first cell layer occupying around 50% of its volume. Oil remained in the cut cells emptied during the washing or the frying operation or in the damaged cells partially filled with starch. Cell detachment, because of starch swelling and dehydration, seemed to be the preferential connection between cell layers. The positive effect of air-drying toward oil uptake reduction could be the restriction of these connections.     

Effect of energy transfer conditions on the chemical degradation of frying oil

The effects of temperature, heating time (continuous or discontinuous mode), and water steam on sunflower oil deterioration have been investigated. Oil was heated at three temperatures, 120, 150, and 190 °C, during a total period of 60 h to achieve a wide range of degradation degrees. At 190 °C, 9 h of discontinuous heating were achieved, and oil degradation was compared to the previous treatment. Water steam treatment was investigated at two oil temperatures, 120 and 150 °C, by frying food model samples that provided a vapor flow of 1.2 g/min during about 30 h. Energy consumptions of the fryers have been measured for each experiment. Thermooxidative degradation of heated oils was evaluated by the measurement of conjugated dienes, viscosity and total polar compounds. All these indicators showed that for the same heating time, oil degradation was more important at 190 °C, and most of all for an intermittent heating. However, the results showed a good correlation between oil degradation and the fryer energy consumption for all the heating experiments, continuous or discontinuous. The presence of water seemed to modify this correlation. These results highlight the complexity of oil degradation during frying, depending on oil temperature, heating mode and presence of water, which can be expressed in energy consumption.