Investigation of structural and electrochemical properties of Na2Mn2(SO4)3 cathode for sodium-ion batteries

Journal of Materials Science: Materials in Electronics - Electrode materials with the benefits of high working voltage, low cost, and environmental benign are needed for the realization of...     

Synergistic evaluation of AgO2 nanoparticles with ceftriaxone against CTXM and blaSHV genes positive ESBL producing clinical strains of Uro‐pathogenic E. coli

The silver oxide nanoparticles (AgO₂ ‐NPs) were synthesised using silver foil as a new precursor in wet chemical method. X‐ray diffraction analysis shows crystallographic structures of AgO₂ ‐NPs with crystallite size of 35.54 nm well‐matched with standard cubic structure. Scanning electron microscopy analysis clearly shows the random distribution of spherical‐shaped nanoparticles. Energy dispersive X‐ray analysis confirmed the purity of the samples as it shows no impurity element. Fourier transforms infra‐red analysis confirmed the formation of AgO₂ ‐NPs with the presence of Ag‐O‐Ag stretching bond. All the techniques also confirmed the loading of ceftriaxone drug on the surface of AgO₂ ‐NPs. This study also described the effect of AgO₂ ‐NPs having synergistic activity with β lactam antibiotic i.e. ceftriaxone against ESBL generating Escherichia coli (E. coli). Among isolated strains of E. coli, 60.0% were found to be ESBL producer. The synergistic activities of AgO₂ ‐NPs with ceftriaxone suggest that these combinations are effective against MDR‐ESBL E. coli strains as evident by increase in zone sizes. The present study observed rise in MDR‐ESBL E. coli with polymorphism of blaCTXM and blaSHV causing UTI infections in Pakistani population. The antibiotic and AgO₂ ‐NPs synergistic effect can be used as an efficient approach to combat uro‐pathogenic infections.Inspec keywords: antibacterial activity, nanofabrication, nanomedicine, drugs, nanoparticles, microorganisms, crystallites, scanning electron microscopy, silver compounds, X‐ray diffraction, X‐ray chemical analysis, Fourier transform infrared spectra, organic compounds, geneticsOther keywords: synergistic evaluation, clinical strains, silver oxide nanoparticles, silver foil, wet chemical method, X‐ray diffraction analysis, crystallographic structures, standard cubic structure, spherical‐shaped nanoparticles, energy dispersive X‐ray analysis, ceftriaxone drug, synergistic activity, ESBL producer, scanning electron microscopy, Fourier transform infrared analysis, Escherichia coli, blaSHV gene positive ESBL, crystallite size, random distribution, β lactam antibiotics, MDR‐ESBL E. coli strains, polymorphism, blaCTXM, uro‐pathogenic infections, uro‐pathogenic E. coli, AgO₂      

Correction to: Deposition of bismuth sulfide and aluminum doped bismuth sulfide thin films for photovoltaic applications

Journal of Materials Science: Materials in Electronics -     

Novel Positive Multi-Layer Graph Based Method for Collaborative Filtering Recommender Systems

Recommender systems play an increasingly important role in a wide variety of applications to help users find favorite products. Collaborative filtering has remarkable success in terms of accuracy and becomes one of the most popular recommendation methods. However, these methods have shown unpretentious performance in terms of novelty, diversity, and coverage. We propose a novel graph-based collaborative filtering method, namely Positive Multi-Layer Graph-Based Recommender System (PMLG-RS). PMLG-RS involves a positive multi-layer graph and a path search algorithm to generate recommendations. The positive multi-layer graph consists of two connected layers: the user and item layers. PMLG-RS requires developing a new path search method that finds the shortest path with the highest cost from a source node to every other node. A set of experiments are conducted to compare the PMLG-RS with well-known recommendation methods based on three benchmark datasets, MovieLens-100K, MovieLens-Last, and Film Trust. The results demonstrate the superiority of PMLG-RS and its high capability in making relevant, novel, and diverse recommendations for users.

     

Cellulose acetate (CA) hybrid membrane prepared by phase inversion method combined with chemical reaction with enhanced permeability and good anti-fouling property

The CA hybrid membrane with enhanced anti-fouling property and higher permeability was prepared by nonsolvent induced phase separation method combined with chemical reaction. The impacts of different solvents (N-methyl-2-pyrrolidone, N, N- Dimethylacetamide, Dimethyl sulfoxide and N, N-Dimethylformamide), organic acids (citric acid/fumaric acid) and titanium dioxide (TiO₂) nanoparticles (NPs) on the separation performance and thermal stability of CA hybrid membranes were investigated. Results showed that the introduction of organic acids to membrane matrix caused asymmetry in the membrane structure with more uniform pore size distribution and higher porosity (82.5%). This is attributed to the production of CO₂ bubbles by a reaction between organic acid in the casting solution and salt in the coagulation bath. Meanwhile, a tremendous rise in anti-fouling property (from 89.7% to 94%), pure water flux (from 329.7 to 821.5 L/m² h) and permeation flux (from 265.8 to 546.3 L/m² h) indicates a significant improvement in the hydrophilicity and the permeability of prepared membranes. In addition, a significant improvement in thermal stability (by 90°C) was achieved owing to the formation of dative bonds between TiO₂ NPs and CA polymer. Therefore, this approach can significantly improve the anti-fouling property and the separation performance of the CA membrane.     

Bandwidth allocation under end‐to‐end percentile delay bounds

We describe an efficient and accurate approximation method for calculating the bandwidth that should be allocated on each link along the path of a point‐to‐point Multiprotocol Label Switching connection, so that the end‐to‐end delay D is less than or equal to a given value T with a probability γ, that is, P(D ≤ T) = γ. We model a connection by a tandem queuing network of infinite capacity queues. The arrival process of packets to the connection is assumed to be bursty and correlated and it is depicted by a two‐stage Markov‐Modulated Poisson Process. The service times are exponentially distributed. The proposed method uses only the first queue of the tandem queuing network to construct an upper and lower bound of the required bandwidth so that P(D ≤ T) = γ. Subsequently, we estimate the required bandwidth using a simple interpolation function between the two bounds. Extensive comparisons with simulation showed that the results obtained have an average relative error of 1.25%. Copyright © 2011 John Wiley & Sons, Ltd.     

Discovering Non-Cooperating Nodes by Means of Learning Automata in the Internet of Things

Internet of Things (IoT) refers to a set of things that are wirelessly connected. The lack of cooperation of nodes, which is due to the reduction of energy level, leads to non-cooperating nodes. Discovering non-cooperating nodes is regarded as one of the main challenges of IoT. In this paper, we addressed this issue by using learning automata where misbehavior of non-cooperating nodes is identified and removed from the network. Simulation results of the proposed method were compared with those of previous works and methods; it was found that the proposed method optimized the other methods in terms of power consumption, throughput, the precision of discovering non-cooperating nodes, and false-positive rate.

     

A study of the influence of crystallite size on the electrical and magnetic properties of CuFe2O4

An attempt has been made to clarify the fundamental assumption that the properties of materials change as the crystallite size of the material is reduced below 100 nm. CuFe₂O₄ samples of different crystallite sizes were prepared by the sol–gel and combustion methods and then analyzed by X-ray diffraction (XRD), thermal analyses (TGA/DTG) and scanning electron microscopy (SEM) techniques. The magnetic properties were studied by measuring the AC magnetic susceptibility (χ) and the Mössbauer spectroscopy. The DC electrical resistivity, dielectric constant, dielectric loss tangent, Curie temperature and hyperfine splitting of the samples change with the crystallite size. The change in the electrical properties is attributed to the formation of discrete energy levels instead of the bands. However, the magnetic parameters change due to the existence of non magnetic surface layers. The isomer shift and the hyperfine splitting show gradual increase with the increase in crystallite sizes.     

Thermal evaporation and condensation synthesis of metallic Zn layered polyhedral microparticles

Metallic zinc layered polyhedral microparticles have been fabricated by thermal evaporation and condensation technique using zinc as precursor at 750 °C for 120 min and NH₃ as a carrier gas. The zinc polyhedral microparticles with oblate spherical shape are observed to be 2-9 μm in diameter along major axes and 1-7 μm in thickness along minor axes. The structural, compositional and morphological characterizations were performed by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). A vapour-solid (VS) mechanism based growth model has been proposed for the formation of Zn microparticles. Room temperature photoluminescence (PL) emission spectrum of the product exhibited a strong emission band at 369 nm attributed to the radiative recombination of electrons in the s, p conduction band near Fermi surface and the holes in the d bands generated by the optical excitation.     

Solvo-solid preparation of Zn3N2 hollow structures; their PL yellow emission and hydrogen absorption characteristics

Zinc nitride (Zn₃N₂) hollow structures with 10-25 μm size have been prepared by solvo-solid approach using aqueous ammonia treated Zn precursor at reaction temperature of 600 °C for reaction time of 240 min under ammonia gas flow. The structural, compositional and morphological characterizations of the as-obtained product were performed by XRD, EDS and SEM. Room temperature photoluminescence (PL) spectrum of zinc nitride hollow structures (ZNHSs) exhibited UV emission band at 384 nm and a defect related yellow emission band at 605 nm. The first ever studies on hydrogen absorption characteristics of ZNHSs performed at 373 K showed an absorption capacity of 1.29 wt.%. Growth mechanism proposed for the formation of ZNHSs is also discussed briefly.