Inhibition of Aspergillus VosA protein by lactic acid bacteria metabolites (in silico study)

In this work, we performed an in silico study using 3D structure protein of VosA, and analyzed the protein interaction via molecular docking using PyRx to test the inhibition efficacy of 15 metabolites compounds produced by lactic acid bacteria in conidia germination protein of Aspergillus. The antifungal docking findings revealed that these compounds showed good interactions and binding affinity against the target involved in conidia germination. The highest binding energy (-6.3 kcal/mol) was given by stearic acid. This interaction is due to the residue amines Ser and Phe. Palmitic acid also showed a good binding affinity with -6 kcal/mol. Lactic acid has not the same efficiency as palmitic, and stearic acid, which represented a value of -3.6 kcal/mol, the values recorded by cytidine was from -5 kcal/mol, which was also important compared to oxalic and acetic acid. DOI: http://dx.doi.org/10.5281/zenodo.560999

Orthogonal Signal Correction to Improve Stability Regression Model in Gas Sensor Systems

Metal oxide sensors are the most often used in electronic nose devices because of their high sensitivity, long lifetime, and low cost. However, these sensors suffer from a lack of response stability making the electronic nose systems useless in industrial applications. The sensor instabilities are particularly caused by incomplete recovery process producing gradual drifts in the sensor responses. This paper focuses on a signal processing method combining baseline manipulation and orthogonal signal correction technique in order to reduce effectively the drift impact from the sensor outputs. The proposed signal processing is explored using experimental data obtained from a gas sensor array responding to various concentrations of pine essential oil vapors. Partial Least Square method is then applied on the corrected dataset to establish a regression model for the estimation of gas concentration. In this work, we show essentially how our drift correction approach can help to improve significantly the stability of the regression model, while ensuring good accuracy

Induced Spin-texture at 3dd Transition Metal/Topological Insulator Interfaces

While some of the most elegant applications of topological insulators, such as quantum anomalous Hall effect, require the preservation of Dirac surface states in the presence of time-reversal symmetry breaking, other phenomena such as spin-charge conversion rather rely on the ability for these surface states to imprint their spin texture on adjacent magnetic layers. In this work, we investigate the spin-momentum locking of the surface states of a wide range of monolayer transition metals (3$d$-TM) deposited on top of Bi$_{2}$Se$_{3}$ topological insulators using first principles calculations. We find an anticorrelation between the magnetic moment of the 3$d$-TM and the magnitude of the spin-momentum locking {\em induced} by the Dirac surface states. While the magnetic moment is large in the first half of the 3$d$ series, following Hund's rule, the spin-momentum locking is maximum in the second half of the series. We explain this trend as arising from a compromise between intra-atomic magnetic exchange and covalent bonding between the 3$d$-TM overlayer and the Dirac surface states. As a result, while Cr and Mn overlayers can be used successfully for the observation of quantum anomalous Hall effect or the realization of axion insulators, Co and Ni are substantially more efficient for spin-charge conversion effects, e.g. spin-orbit torque and charge pumping.Comment: 5 pages, 7 figure

The impact of anion elements on the engineering of the electronic and T optical characteristics of the two dimensional monolayer janus MoSSe for nanoelectronic device applications

Two-dimensional (2D) materials have gained prominent attention in the nano-electronics arena, owing to their tunable electronic and optical features. Here, the physical properties of a janus MoSSe monolayer are examined upon the chemically co-doping of S/Se sites by non-metallic and halogen elements (C, Si, N, P, As, and F) employing first-principles calculations. Accordingly, an alteration of both the upper valence and the lower conduction states is revealed for janus MoSSe monolayer upon the replacement of both S and Se anion host atoms by sp-elements (C, Si, N, P, As, and F). A shift in the lowest conduction band underneath the Fermi energy level (EF) occurs in janus MoSSe monolayer when both S and Se elements are replaced by (F, F) atoms. This effectively conducted to a system with an n-type character. In contrast, the highest valence bands moved upward EF owing to the co-doping effect of C, Si, N, P, and As atoms on the janus MoSSe monolayer with p-type nature. The key features of the optical spectra, such as the optical absorption, reflectivity, and electron loss functions of the co-doped janus MoSSe monolayer are inspected. Our results imply a modification in the low-energy photon regime of the co-doped janus MoSSe monolayer at S and Se host atoms by non-metallic sp-elements comparatively to the free-standing monolayer. A reduction in the optical absorption and an increase in the reflectivity at low-energy photon window are detected when the janus MoSSe monolayer is co-doped by (C, Si), (N, P), (P,As), and (F,F) elements, respectively at S and Se chalcogen atoms. The current study infers that the co-doping S and Se sites of janus MoSSe monolayers, with sp- elements, can be beneficial in the future applications of 2D materials for the field-effect transistors and nano-electronic devices

Induced spin textures at 3\u3ci\u3ed\u3c/i\u3e transition metal–topological insulator interfaces

While some of the most elegant applications of topological insulators, such as the quantum anomalous Hall effect, require the preservation of Dirac surface states in the presence of time-reversal symmetry breaking, other phenomena such as spin-charge conversion rather rely on the ability for these surface states to imprint their spin texture on adjacent magnetic layers. In this Rapid Communication, we investigate the spin-momentum locking of the surface states of a wide range of monolayer transition metals (3d-TM) deposited on top of Bi2Se3 topological insulators using first-principles calculations. We find an anticorrelation between the magnetic moment of the 3d-TM and the magnitude of the spin-momentum locking induced by the Dirac surface states. While the magnetic moment is large in the first half of the 3d series, following Hund’s rule, the spin-momentum locking is maximum in the second half of the series. We explain this trend as arising from a compromise between intra-atomic magnetic exchange and covalent bonding between the 3d-TM overlayer and the Dirac surface states. As a result, while Cr and Mn overlayers can be used successfully for the observation of the quantum anomalous Hall effect or the realization of axion insulators, Co and Ni are substantially more efficient for spin-charge conversion effects, e.g., spin-orbit torque and charge pumping

Structural and optical behaviors of 2D-layered molybdenum disulfide thin film:Experimental and ab-initio insights

The two-dimensional (2D) layered molybdenum disulfide (MoS2) material represents a nominee potent for optoelectronic devices application. In this research work, the experimental characterizations of 2D- MoS2 thin films are reported in terms of various microscopic and spectroscopic techniques. The synthesized MoS2 thin films are grown by employing the pulsed laser deposition (PLD) procedure on SiO2/Si substrates. In order to monitor the deposition rates of ablated films, the buffer argon-gas pressures are varied during the pulsed laser deposition at substrate temperature of 700 °C. The field emission scanning electron microscopy and atomic force microscopy analyzes revealed a change in the surface morphology of MoS2 films when the buffer Ar-gas pressure is varied between 0 and 100 mTorr. For all samples, a 2H-phase is revealed from X-ray diffraction patterns, indicating a reflection (2θ) around 14.85°. By varying the deposition pressure of laser-ablated MoS2 films, the X-ray photoelectron spectroscopy divulged the chemical compositional elements and valence states of Mo and S on the surface of MS2 films with low density of defects. Analysis of the photoluminescence spectroscopy illustrated emission bands spanning from the visible (Vis) to near-infrared (NIR) regimes in the deposition pressures range ~ 0–100 mTorr. This is mainly owing to the change in the recombination of electron–hole pairs and charge transfer between the deposited MoS2 films and SiO2 substrate surface under various buffer gas pressures. Additionally, first-principles electronic structure calculations are performed to qualitatively examine the effect of native point-defect species (sulfur-monovacancy and sulfur-divacancy defects) on the electronic structure and optical properties of 2D- MoS2 sheets. It is unveiled that the variation of compositional sulfur-vacancy defect in MoS2 monolayer creates an in–gap defect levels above the valence states, leading to an acceptor character. Importantly, the enhancement in the optical absorption spectra divulged a shift in the optical gap from Vis-NIR window with the increase of sulfur vacancy contents in MoS2 single-layer. The identification of intrinsic point defects may be beneficial for photovoltaic energy conversion at higher wavelengths by designing next generation 2D-semiconductors, which could be of vital significance for growing 2D layers and multilayers into practical technologies

Electronic structures and magnetic properties of RB4 (R=Yb,Pr,Gd,Tb,Dy)

Most rare-earth tetraborides RB4 have antiferromagnetic ground states except for YbB4 and PrB4. We have investigated the electronic structures and magnetic properties of RB4 (R=Yb, Pr, Gd, Tb, Dy) employing the first-principles total energy band method. It is found that YbB4 has the paramagnetic ground state, while the other tetraborides are in the magnetic ground state, which is in agreement with experiments. We have obtained the spin and orbital magnetic moments and discussed the importance of the spin-orbit interaction and the on-site Coulomb repulsion (U) in these systems. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3058707]ope