The crossover from collective motion to periphery diffusion for 2D adatom-islands on Cu(111)

The diffusion of two dimensional adatom islands (up to 100 atoms) on Cu(111) has been studied, using the self-learning Kinetic Monte Carlo (SLKMC) method [1]. A variety of multiple- and single-atom processes are revealed in the simulations, and the size dependence of the diffusion coefficients and effective diffusion barriers are calculated for each. From the tabulated frequencies of events found in the simulation, we show a crossover from diffusion due to the collective motion of the island to a regime in which the island diffuses through periphery-dominated mass transport. This crossover occurs for island sizes between 13 and 19 atoms. For islands containing 19 to 100 atoms the scaling exponent is 1.5, which is in good agreement with previous work. The diffusion of islands containing 2 to 13 atoms can be explained primarily on the basis of a linear increase of the barrier for the collective motion with the size of the island

Imposed Switching Frequency Direct Torque Control of Induction Machine Using Five Level Flying Capacitors Inverter

The paper proposes a new control structure for sensorless induction motor drive based on a five-level voltage source inverter (VSI). The output voltages of the five-level VSI can be represented by nine groups. Then, the amplitude and the rotating velocity of the flux vector can be controlled freely. Both fast torque and optimal switching logic can be obtained. The selection is based on the value of the stator flux and the torque. This paper investigates a new control structure focused on controlling switching frequency and torque harmonics contents. These strategies, called ISFDTC, indeed combines harmoniously both these factors, without compromising the excellence of the dynamical performances typically conferred to standard DTC strategies. The validity of the proposed control technique is verified by Matlab/Simulink. Simulation results presented in this paper confirm the validity and feasibility of the proposed control approach and can be tested on experimental setup.Peer reviewe

Atomistic studies of thin film growth

We present here a summary of some recent techniques used for atomistic studies of thin film growth and morphological evolution. Specific attention is given to a new kinetic Monte Carlo technique in which the usage of unique labeling schemes of the environment of the diffusing entity allows the development of a closed data base of 49 single atom diffusion processes for periphery motion. The activation energy barriers and diffusion paths are calculated using reliable manybody interatomic potentials. The application of the technique to the diffusion of 2-dimensional Cu clusters on Cu(111) shows interesting trends in the diffusion rate and in the frequencies of the microscopic mechanisms which are responsible for the motion of the clusters, as a function of cluster size and temperature. The results are compared with those obtained from yet another novel kinetic Monte Carlo technique in which an open data base of the energetics and diffusion paths of microscopic processes is continuously updated as needed. Comparisons are made with experimental data where available

Obtaining N-Enriched Mesoporous Carbon-Based by Means of Gamma Radiation

In this paper, we present the results of the gamma irradiation method to obtain N-doped mesoporous activated carbons. Nitrogen-enriched mesoporous carbons were prepared from three chosen commercial activated carbons such as Carbon Black OMCARB C-140, KETJENBLACK EC-600JD and PK 1-3 Norit. HRTEM, SEM, Raman spectra, elemental analysis, XPS studies and widely approved N2 adsorption–desorption measurements allowed us to evaluate the effectiveness of N atom insertion and its influence on the BET surface area and the pore structure of modified carbons. The obtained materials have an exceptionally high N content of up to 3.2 wt.%. Additionally, selected N-doped activated carbons were fully characterized to evaluate their applicability as carbon electrode materials with particular emphasis on Oxygen Reduction Reaction (ORR). The proposed method is a relatively facile, efficient and universal option that can be added to the already known methods of introducing heteroatoms to different carbons.Innovation Incubator 4.0 NCU (Poland) 5/2021 MNISW/2020/331NCU competition Mobility 4 edition project 60/2021/Mobilit

The preclinical and clinical progress of bacteriophages and their lytic enzymes : the parts are easier than the whole

The therapeutic potential of phages has been considered since their first identification more than a century ago. The evident concept of using a natural predator to treat bacterial infections has, however, since then been challenged considerably. Initially, the vast success of antibiotics almost eliminated the study of phages for therapy. Upon the renaissance of phage therapy research, the most provocative and unique properties of phages such as high specificity, self-replication and co-evolution prohibited a rapid preclinical and clinical development. On the one hand, the typical trajectory followed by small molecule antibiotics could not be simply translated into the preclinical analysis of phages, exemplified by the need for complex broad spectrum or personalized phage cocktails of high purity and the more complex pharmacokinetics. On the other hand, there was no fitting regulatory framework to deal with flexible and sustainable phage therapy approaches, including the setup and approval of adequate clinical trials. While significant advances are incrementally made to eliminate these hurdles, phage-inspired antibacterials have progressed in the slipstream of phage therapy, benefiting from the lack of hurdles that are typically associated with phage therapy. Most advanced are phage lytic enzymes that kill bacteria through peptidoglycan degradation and osmotic lysis. Both phages and their lytic enzymes are now widely considered as safe and have now progressed to clinical phase II to show clinical efficacy as pharmaceutical. Yet, more initiatives are needed to fill the clinical pipeline to beat the typical attrition rates of clinical evaluation and to come to a true evaluation of phages and phage lytic enzymes in the clinic

An ethnobotanical survey of spontaneous plants used in traditional medicine in the region of Aures, Algeria

This study carried out in the Aures region (Algeria) between September 2018 and March 2019, allowed us to identify spontaneous plants used in the region and gather all the information concerning the therapeutic practices of the local population. Based on a series of ethnobotanical surveys, we have identified 112 medicinal species belonging to 49 families, of which Asteraceae, Poaceae, Lamiaceae, Fabaceae, Amaranthaceae and Cupressaceae are the most represented. The leaves were the most used plant parts (28.86%), and the decoction (37.68%) represents the most frequently used mode of preparation. In addition, the remedies were prepared essentially from single species (81.15%) and were used mainly in the treatment of digestive disorders (23.99%). The study has also shown that women, married people, the elderly and illiterates people had the better knowledge of the use of medicinal plants. These results indicate that local population has a fairly deep empirical and traditional knowledge of phytotherapy. However, this knowledge is endangered mainly because of the mode of transmission which is based on oral tradition and an urgent transcription is needed to avoid the loss of this heritage

Unveiling the structural transformations of the PW11Co@ZIF-67 nanocomposite induced by thermal treatment

A guest@host POM@ZIF nanocomposite—PW11Co@ZIF-67—has been synthesized using an in situ strategy. This new nanocomposite exhibits (i) individually ZIF-67-cage-confined POM units, (ii) structural defects in the ZIF-67 host induced by the POM, and (iii) charge transfer from the ZIF-67 to the confined POM. In addition, it has served as a template to produce a set of derived samples by applying thermal treatment at various temperatures (200, 400, 500, 600, and 950 °C) under a N2 flow. We have used multiple characterization techniques, ICP-OES, CHNS analysis, XPS, ATR-IR, PXRD, Raman spectroscopy, N2/ CO2 adsorption analysis, CV, and TEM/EDS, to fully assess the thermally-induced variation tendencies. The first two derivatives—D200 and D400—show the same nanoarrangement as the PW11Co@ZIF-67 precursor, although with incipient signs of both POM and ZIF-67 structural decompositions. The following samples—D500, D600, and D950—exhibit a carbonaceous nature consisting of C-embedded compositionally complex nanoparticles that involve Co and W present as diverse species, metallic/oxide/phosphate/ phosphide. D500 presents the best intrinsic electrochemistry, probably due to the high proportion of pyridinic N moieties doping its C matrix combined with small-sized and highly dispersed Co-enriched nanoparticles. This study focuses on the need for a thorough physicochemical characterization of this class of highly nanostructured materials with a view to exploring their application in electrocatalysis.Portuguese Foundation for Science and Technology POCI-01-0145-FEDER-016422European CommissionPortuguese Foundation for Science and TechnologyEuropean Commission UIDB/50006/2020 UIDP/50006/2020 2021.00771.CEECIND/CP1662/CT0007 CEECIND/03877/2018 CEECIND/00793/201

Network current quality enhancement under nonlinear and unbalanced load conditions using a four-wire inverter-based active shunt filter

The flow of a large current in the neutral conductor of a transmission system is one of the major problems caused by harmonic pollution. This current can assume excessive values and even exceed the current flowing in the phases which can be extremely dangerous both for the equipment and the safety of the personnel. Currently, the parallel or shunt active filter (SAF) or parallel active filter is considered as the most effective solution to mitigate harmonic pollution and restore a sinusoidal current waveform in electrical distribution networks. The SAF can be used to compensate for harmonic currents, as well as that of the reactive power. This paper proposes a SAF circuit based on a four-arm inverter topology. The designed SAF is shown to lead to better harmonic compensation with a reduced THD (Total Harmonic Distortion) level in the presence of nonlinear and unbalanced loads in the network. The other goal of this study is to eliminate the neutral current caused by the unbalance in the polluting loads connected to the distribution network, achieve a near-sinusoidal current waveform and protect the electric network equipment

Self-learning Kinetic Monte-Carlo method: application to Cu(111)

We present a novel way of performing kinetic Monte Carlo simulations which does not require an {\it a priori} list of diffusion processes and their associated energetics and reaction rates. Rather, at any time during the simulation, energetics for all possible (single or multi-atom) processes, within a specific interaction range, are either computed accurately using a saddle point search procedure, or retrieved from a database in which previously encountered processes are stored. This self-learning procedure enhances the speed of the simulations along with a substantial gain in reliability because of the inclusion of many-particle processes. Accompanying results from the application of the method to the case of two-dimensional Cu adatom-cluster diffusion and coalescence on Cu(111) with detailed statistics of involved atomistic processes and contributing diffusion coefficients attest to the suitability of the method for the purpose.Comment: 18 pages, 9 figure