The Influence of Controller Parameters on the Quality of the Train Converter Current

This paper presents a stability analysis of train converters in order to evaluate how the controller parameters affect the absorbed current. The new dynamic model presented in this paper is capable of considering the time-variant nature of the system for the correct tuning of the feedback proportional-integral PI controller, applying a current controlled modulation technique never used in high-power traction converters. The reduction of the harmonic content of the current absorbed by a converter employed at the input stage onboard high-speed trains is really important, considering the interaction with the signaling system set up for traffic control. A computer model of the converter, considering both the power and the control structure, has also been implemented in order to deliver a validated tool for the developed theoretical analysis

Lipase-Mediated Synthesis of Oleoyl Ethanolamide Starting from High-Oleic Sunflower Oil Soapstock

This work describes the lipase-mediated synthesis of oleoyl ethanolamide, a dietary supplement for body weight loss recently approved by FDA. The target compound is prepared by conversion of the oleic acid contained in a mixture of fatty acids recovered by enzymatic hydrolysis of soapstock, a side-product of high oleic sunflower oil refinement. The use of a packed-bed reactor (a glass column loaded with the commercial lipase Lipozyme 435) in continuous flow mode improves the space-time yield of the reaction and the catalyst productivity. The nontoxic, bioderived, and renewable solvent limonene is used in the reaction medium. The process has been run for more than 157 h of continuous operation, demonstrating the stability and efficiency of the biocatalyst. Additionally, at the end of the reaction, only oleoyl ethanolamide crystallizes from the reaction mixture, thus, it is collected by simple filtration of the outlet solution in 53% isolation yield, showing 99% chemical purity, while all the byproducts of the reaction are left behind in the mother liquors

A New Theoretical Approach of Studying Resonances in Single Finline Transitions

In this article an innovative method of studying and removing the resonances, inherently exhibit by some waveguide to microstrip transitions, is presented. By modeling an equivalent circuit, this new approach allows to obtain the constructive parameters of a finline to microstrip transition, only using the values of the resistance and capacitance components of the equivalent circuit. This procedure will allow small microwave design Companies to realize these transitions only implementing circuit analysis software, and not having to afford electromagnetic analysis software, which are very expensive and time-consuming. A full 3D electromagnetic analysis confirms that the simulation results are in excellent agreement with the results obtained by the new equations discussed in this work

Giant Quadrupole Resonances in 208Pb, the nuclear symmetry energy and the neutron skin thickness

Recent improvements in the experimental determination of properties of the Isovector Giant Quadrupole Resonance (IVGQR), as demonstrated in the A=208 mass region, may be instrumental for characterizing the isovector channel of the effective nuclear interaction. We analyze properties of the IVGQR in 208Pb, using both macroscopic and microscopic approaches. The microscopic method is based on families of non-relativistic and covariant Energy Density Functionals (EDF), characterized by a systematic variation of isoscalar and isovector properties of the corresponding nuclear matter equations of state. The macroscopic approach yields an explicit dependence of the nuclear symmetry energy at some subsaturation density, for instance S(\rho=0.1 fm^{-3}), or the neutron skin thickness \Delta r_{np} of a heavy nucleus, on the excitation energies of isoscalar and isovector GQRs. Using available data it is found that S(\rho=0.1 fm{}^{-3})=23.3 +/- 0.6 MeV. Results obtained with the microscopic framework confirm the correlation of the \Delta r_{np} to the isoscalar and isovector GQR energies, as predicted by the macroscopic model. By exploiting this correlation together with the experimental values for the isoscalar and isovector GQR energies, we estimate \Delta r_{np} = 0.14 +/- 0.03 fm for 208Pb, and the slope parameter of the symmetry energy: L = 37 +/- 18 MeV

Los procesos intervenientes en la configuración de las identidades

Fil: López, Humberto. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Rodríguez, Cecilia Inés. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Hasan, Alma F.. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y SocialesFil: Brenna, Ana. Universidad Nacional de Cuyo. Facultad de Ciencias Políticas y Sociale

Stereoselective synthesis of whisky lactone isomers catalyzed by bacteria in the genus Rhodococcus

Whisky lactone is a naturally occurring fragrance compound in oak wood and is widely used as a sensory additive in food products. However, safe and efficient methods for the production of its individual enantiomers for applications in the food industry are lacking. The aim of this study was to develop an efficient and highly stereoselective process for the synthesis of individual enanti omeric forms of whisky lactones. The proposed three-step method involves (1) column chromatography separation of a diastereo isomeric mixture of whisky lactone, (2) chemical reduction of cis-and trans -whisky lactones to corresponding syn-and anti -diols, and (3) microbial oxidation of racemic diols to individual enantiomers of whisky lactone. Among various bacteria in the genera Dietzia , Gordonia , Micrococcus , Rhodococcus, and Streptomyces , R. erythropolis DSM44534 and R. erythropolis PCM2150 effectively oxidized anti-and syn -3-methyl-octane-1,4-diols (1a-b) to corresponding enantiomerically pure cis-and trans -whisky lactones, indicating high alcohol dehydrogenase activity. Bio-oxidation catalyzed by whole cells of these strains yielded enantiom erically pure isomers of trans -(+)-(4S ,5R ) (2a), trans -(-)-(4R ,5S ) (2b), and cis -(+)-(4R ,5R ) (2d) whisky lactones. The optical density of bacterial cultures and the impact of the use of acetone powders as catalysts on the course of the reaction were also evaluated. Finally, the application of R. erythropolis DSM44534 in the form of an acetone powder generated the enantiom erically enriched cis -(-)-(4S ,5S )- isomer (2c) from the corresponding syn -diol (1b). The newly developed method provides an improved approach for the synthesis of chiral whisky lactones

Effetto dell’intermittenza della corrente di protezione nei sistemi di protezione catodica dell’acciaio

The paper reports the results of a preliminary research study on the effects of protection current intermittence on the cathodic protection conditions of buried or immersed pipelines. It is well known that cathodic protection has chemical and electrochemical beneficial effects on carbon steel, which do not disappear instantly in correspondence to the current interruption. According to this premise, laboratory tests of intermittent cathodic protection in which the current has been interrupted cyclically were carried out on carbon steel specimens in soil-simulating solution. The effects of the duration of the current-off time, the number of on-off cycles, and of the applied current density have been studied. Potential has been monitored weekly and the residual corrosion rate was calculated by means of a simple electrochemical model

One-pot multi-enzymatic synthesis of the four stereoisomers of 4-methylheptan-3-ol

The use of pheromones in the integrated pest management of insects is currently considered a sustainable and environmentally benign alternative to hazardous insecticides. 4-Methylheptan-3-ol is an interesting example of an insect pheromone, because its stereoisomers are active towards different species. All four possible stereoisomers of this compd. were prepd. from 4-methylhept-4-en-3-one by a one-pot procedure in which the two stereogenic centers were created during two sequential redns. catalyzed by an ene-reductase (ER) and an alc. dehydrogenase (ADH), resp

TiO2 Microparticles Incorporation in Coatings Produced by Plasma Electrolytic Oxidation (PEO) on Titanium

This research describes the influence of two types of particles, namely rutile and anatase microparticles (average d < 5 μm), on the morphology, structure, and anticorrosive properties of PEO coatings on titanium produced in an alkaline solution based on NaOH and sodium metasilicates. The paper reports the experimental results relating to the study of the influence of the electrical regime and working frequency of the anodizing treatment on the interaction between the particles, the substrate, and the oxide to determine the optimal conditions that favour the incorporation of the particles and the production of a thick oxide. PEO coatings are characterized by using a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) analysis, and X-ray diffraction (XRD) testing. The electrochemical behaviour is evaluated by free corrosion potential monitoring and electrochemical impedance spectroscopy analysis (EIS) performed in a sulphuric acid solution. The particles are successfully incorporated into the coating under any electrical condition and at any frequency. However, only treatments carried out at 1000 Hz allow the production of coatings that combine a large thickness (up to 50 μm) and improved anticorrosion behaviour. In contrast, oxide layers produced at 20 Hz and in DC show a quite damaged structure, affecting their anticorrosion behaviour and resulting in lower corrosion potential and impedance values