Effect of Adventitious Carbon on Pit Formation of Monolayer MoS2

Forming pits on molybdenum disulfide (MoS₂) monolayers is desirable for (opto)electrical, catalytic, and biological applications. Thermal oxidation is a potentially scalable method to generate pits on monolayer MoS₂, and pits are assumed to preferentially form around undercoordinated sites, such as sulfur vacancies. However, studies on thermal oxidation of MoS₂ monolayers have not considered the effect of adventitious carbon (C) that is ubiquitous and interacts with oxygen at elevated temperatures. Herein, the effect of adventitious C on the pit formation on MoS₂ monolayers during thermal oxidation is studied. The in situ environmental transmission electron microscopy measurements herein show that pit formation is preferentially initiated at the interface between adventitious C nanoparticles and MoS₂, rather than only sulfur vacancies. Density functional theory (DFT) calculations reveal that the C/MoS₂ interface favors the sequential adsorption of oxygen atoms with facile kinetics. These results illustrate the important role of adventitious C on pit formation on monolayer MoS₂.     

Resource Management in a Peer to Peer Cloud Network for IoT

Wireless Personal Communications - Software-Defined Internet of Things (SDIoT) is defined as merging heterogeneous objects in a form of interaction among physical and virtual entities. Large scale...     

Characterization of Extracellular Vesicles from Preconditioned Human Adipose-Derived Stromal/Stem Cells

Cell-free therapy using extracellular vesicles (EVs) from adipose-derived mesenchymal stromal/stem cells (ASCs) seems to be a safe and effective therapeutic option to support tissue and organ regeneration. The application of EVs requires particles with a maximum regenerative capability and hypoxic culture conditions as an in vitro preconditioning regimen has been shown to alter the molecular composition of released EVs. Nevertheless, the EV cargo after hypoxic preconditioning has not yet been comprehensively examined. The aim of the present study was the characterization of EVs from hypoxic preconditioned ASCs. We investigated the EV proteome and their effects on renal tubular epithelial cells in vitro. While no effect of hypoxia was observed on the number of released EVs and their protein content, the cargo of the proteins was altered. Proteomic analysis showed 41 increased or decreased proteins, 11 in a statistically significant manner. Furthermore, the uptake of EVs in epithelial cells and a positive effect on oxidative stress in vitro were observed. In conclusion, culture of ASCs under hypoxic conditions was demonstrated to be a promising in vitro preconditioning regimen, which alters the protein cargo and increases the anti-oxidative potential of EVs. These properties may provide new potential therapeutic options for regenerative medicine.     

Well‐functioned photovoltaics based on nanofibers composed of PBDT‐TIPS‐DTNT‐DT and graphenic precursors thermally modified by polythiophene,polyaniline and polypyrrole

Reduced graphene oxide nanosheets modified by conductive polymers including polythiophene (GPTh), polyaniline (GPANI) and polypyrrole (GPPy) were prepared using the graphene oxide as both substrate and chemical oxidant. UV–visible and Raman analyses confirmed that the graphene oxide simultaneously produced the reduced graphene oxide and polymerized the conjugated polymers. The prepared nanostructures were subsequently electrospun in mixing with poly(3‐hexylthiophene) (P3HT)/phenyl‐C71‐butyric acid methyl ester (PC₇₁BM) and poly[bis(triisopropylsilylethynyl)benzodithiophene‐bis(decyltetradecylthien)naphthobisthiadiazole] (PBDT‐TIPS‐DTNT‐DT)/PC₇₁BM components and embedded in the active layers of photovoltaic devices to improve the charge mobility and efficiency. The GPTh/PBDT‐TIPS‐DTNT‐DT/PC₇₁BM devices demonstrated better photovoltaic features (J_sc = 11.72 mA cm^?2, FF = 61%, V_oc = 0.68 V, PCE = 4.86%, μ_h = 8.7 × 10^?3 cm² V^–1 s^?1 and μ_e = 1.3 × 10^?2 cm² V^–1 s^?1) than the GPPy/PBDT‐TIPS‐DTNT‐DT/PC₇₁BM (J_sc = 10.30 mA cm^?2, FF = 60%, V_oc = 0.66 V, PCE = 4.08%, μ_h = 1.4 × 10^?3 cm² V^–1 s^?1 and μ_e = 8.9 × 10^?3 cm² V^–1 s^?1) and GPANI/PBDT‐TIPS‐DTNT‐DT/PC₇₁BM (J_sc = 10.48 mA cm^?2, FF = 59%, V_oc = 0.65 V, PCE = 4.02%, μ_h = 8.6 × 10^?4 cm² V^–1 s^?1 and μ_e = 7.8 × 10^?3 cm² V^–1 s^?1) systems, assigned to the greater compatibility of PTh in the nano‐hybrids and the thiophenic conjugated polymers in the bulk of the nanofibers and active thin films. Furthermore, the PBDT‐TIPS‐DTNT‐DT polymer chains (3.35%–5.04%) acted better than the P3HT chains (2.01%–3.76%) because of more complicated conductive structures. © 2019 Society of Chemical Industry     

Promising features for poly(vinyl chloride) enriched with Moringa oleifera: Photostability,rheological, mechanical,thermal and antibacterial properties

Poly(vinyl chloride) (PVC) was loaded with various contents of Moringa oleifera (MO) leaves extract. The changes in the structure arising after loading MO into the polymeric matrix were monitored. In addition, their rheological and mechanical properties were investigated. Some thermal analyses techniques were performed to demonstrate any change in the thermal stability of PVC before and after adding MO. PVC/MO exhibited noticeable antibacterial efficiency when evaluated against Gram-positive and Gram-negative bacteria. A favorable antibacterial efficiency of PVC/MO boosted with increasing of MO content from 5% to 25% by weight when introduced into PVC. The photostability of PVC enriched with MO was investigated. The change in the rate of dehydrochlorination for PVC was detected. It was indicated with liberating HCl from the polymeric matrix.     

High Performance Removal of Anionic and Cationic Dye Pollutants with Co<Subscript>3</Subscript>O<Subscript>4</Subscript> Modified Nanoclinoptilolite: Kinetics and Adsorption Equilibrium Studies

In this paper Co₃O₄ doped nanoclinoptilolite was synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX) techniques. The adsorption efficiency for removing of methylene blue was about 95% in 10 min. The effect of some factors such as adsorbent dose, concentration of analyte and pH was investigated for enhancing the removing efficiency. Moreover Freundlich and Langmuir patterns were plotted for this new nanocomposite. Maximum of adsorption capacity was obtained from slope of Langmuir and was about 25 mg/g. The kinetic study for methylene blue shows a second order kinetic with rate constant about 0.02 g/mg/min. The prepared nanocomposite was successfully applied for removing some color compounds such as methylene blue, methyl green, and methyl red and also binary dye mixtures.     

A delicate maneuver on conjugated rod-rod structures composed of poly(3-hexylthiophene) and polyaniline subtending patched-fibrillar,ringed-fibrillar,double-fibrillar and sandwiched configurations

Full-conjugated rod-rod structures comprising patched-fibrillar, ringed-fibrillar, and double-fibrillar configurations were designed from poly(3-hexylthiophene) (homo-P3HT) and polyaniline (PANI) nanorods in chloroform, p-xylene, and amyl acetate dilute solutions, respectively. Solvent quality, seeding effect, and constituent material were focused while characterizing the developed structures. By exacerbating the processing solvent quality from chloroform to p-xylene, a ringed-fibrillar configuration was detected instead of patched-fibrillar structure. In a poor solvent, double-fibrillar structures were acquired from homo-P3HT chains and PANI nanorods. Towards a poorer solvent, P3HT chains were capable of developing their own crystals by less sensing presence of PANI nanorods as seeds. In another experiment, by copolymerization of both P3HT and PANI with crystallizable PEG blocks, sandwiched rod-rod mixed-brush single crystals were developed. Molecular weight of neither P3HT nor PANI was effective on surface patterning of P3HT/PANI mixed-brushes. Via elevating crystallization temperature, PANI dispersed patterns became more delicate and their width decreased from 80 to 160 nm to 12–30 nm. P3HT backbones were tethered with a extended flat-on orientation onto the PEG substrate at either low or high crystallization temperatures. Beside sandwiched single crystals seeded with homo-PEG tiny crystals, slightly and highly curved half-ring crystals were also developed in the PEG-b-P3HT systems.

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Soy protein isolate nanocomposite film enriched with eugenol,an antimicrobial agent: Interactions and properties

Nanocomposites films were designed from soy protein isolates (SPI), clays (Na⁺‐MMT), and eugenol an antimicrobial agent. Interactions between Na⁺‐MMT and eugenol were evidenced by a shift of the d‐spacing by X‐ray diffraction analysis. The addition of Na⁺‐MMT (5 and 7.5% w/w) in SPI solution increased its shear thinning behavior and its consistency. Accordingly, a good exfoliation of clays in SPI films was observed. The glass transition temperature of SPI films was impacted by the clays addition but not the water vapor permeability. In contrast, the addition of eugenol in SPI solution did not affected the consistency but induced a decrease of the SPI film T_g and an increase of the water vapor permeability. The presence of eugenol counterbalanced the effect of clays on consistency of film‐forming solution. The clay intercalation process was facilitated and the water vapor permeability and active agent release were modified. The presence of clay did not affect the antibacterial effect of eugenol/SPI films. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45941.     

Multi-band Tight-Binding Model of MoS 2 Monolayer

In this theoretical study, the band structure of MoS2 monolayer was initially numerically calculated using an 11-band tight-binding Hamiltonian model. Then, the contributions of d and p orbitals on the density of states (DOS), electronic heat capacity (EHC), and Pauli magnetic susceptibility (PMS) of the system were investigated based on the mentioned model and the Green’s function method. Also, the temperature dependence of the EHC and PMS is compared for the d and the p orbitals. An obvious gap was observed in the band structure and DOS of the MoS2 monolayer system, which is in good agreement with previous works. Moreover, due to the orbital overlap, Van Hove singularities appear. Then, as a result of this, a crossover occurs in the curves of PMS, which are divided into a low- and high-temperature region. Further, a Schottky anomaly is observed in the EHC curves. Overall, in this paper, we have introduced a method to investigate the electronic properties of $${{ {MoS}}}_{2}$$ monolayer that can be applied to other monolayer dichalcogenides.     

Design of a Symmetric CPW-Fed Patch Antenna for WLAN/WIMAX Applications Using ANN

The upper bound capacity based on the SINR model is a very important parameter when evaluating the performance of the multi-hop wireless ad hoc networks. In this paper, a new upper bound capacity algorithm is proposed. Firstly, we analyzed the classical physics SINR model over the Rayleigh fading channels to establish the relationship between density of nodes and path outage probability. Then, we developed the closed-form expression of the upper bound transmission capacity based on the Weber model for the random networks. Finally, we evaluated effects of parameters in the communication range, density, SINR threshold and fading factors, and consequently transmission capacity of the network by sensitivity analysis. The numerical simulation showed that the optimum density of nodes was existed to obtain the upper bound transmission capacity. The capacity increased firstly and then decreased over the density of nodes increasing. It affected by channel fading factor and communication range sensitively.