Comparison of prolonged antibacterial activity and release profile of propolis‐incorporated PVA nanofibrous mat,microfibrous mat,and film

Propolis as a natural antibacterial agent was incorporated into the poly(vinyl alcohol) (PVA) in different forms of nanofiber, microfiber, and film. The successful fabrication of uniform nanofibers with 85–314 nm diameters and microfibers with 2.02 μm diameter was proved by scanning electron microscopy. Structural analysis by Fourier transform infrared spectroscopy and X‐ray diffraction and swelling properties confirmed the formation PVA hydrogel and its H‐bonding to the propolis. Evaluation and comparison of antimicrobial properties of produced samples against Staphylococcus aureus strains revealed that nanofiber mat with 19 mm inhibition zone has 11.76 and 26.67% higher efficiency against bacteria than microfiber mat and film with 17 and 15 mm inhibition zone, respectively. Nanofibrous mat showed sustained release during 96 h by maintaining full antibacterial activity up to 51 h which is of great importance in burn wounds. These results confirm the advanced performance of natural propolis in the form of nanofiber substrate as wound dressing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45794.     

Nanosecond streak photography of discharge initiation on ice surfaces

This paper presents an exploratory experimental study of discharge initiation on surface of ice. The phenomena underlying these processes are, as yet, poorly understood. To elucidate the initiation process in particular, ultra high-speed streak photography was used to observe and analyze the first visible discharges and a number of parameters were investigated. It could be shown that ambient temperature, conductivity of ice surface and the presence of imperfections on the ice surface influence not only the critical voltage for discharge initiation, but also the velocity of discharge development. Some parameters could be identified, which should be investigated further. The present paper is the first stage of a long-term research effort in this new field. This study should enable further experimental investigations and mathematical simulations to gain better understanding of ice surface discharges, specifically in the context of electrical insulation integrity of support insulators in power systems operating under severe atmospheric conditions.     

Specific investigations to quantify heavy damage causes on loading resistor modules

In this paper, premature damage to some static inverter loading resistor modules is analyzed. Furthermore, investigations were carried out to determine the origins and causes of this serious damage occurring on the resistor modules in service. Investigations were preformed on the insulating liquid samples as well as new resistor modules. From the results obtained, it seems that the origin of the damage is from a long-standing, free-burning arc between two resistor windings, following mechanical breakdown.     

Characterization and amino acid sequence of the OXY-2 group beta-lactamase of pI 5.7 isolated from aztreonam-resistant Klebsiella oxytoca strain HB60

EPA's Risk Assessment Guidance for Superfund (RAGS) and later documents provide guidance for estimating exposures received from suburban and agricultural activity patterns and lifestyles. However, these methods are not suitable for typical tribal communities whose members pursue, at least in part, traditional lifestyles. These lifestyles are derived from a long association with all of the resources in a particular region. We interviewed 35 members of a Columbia River Basin tribe to develop a lifestyle-based subsistence exposure scenario that represents a midrange exposure that a traditional tribal member would receive. This scenario provides a way to partially satisfy Executive Order 12,898 on environmental justice, which requires a specific evaluation of impacts from federal actions to peoples with subsistence diets. Because a subsistence diet is only a portion of what is important to a traditional lifestyle, we also used information obtained from the interviews to identify parameters for evaluating impacts to environmental and sociocultural quality of life.     

A perturbation and iterative perturbation analysis of linearly chirped grating lenses of medium Q in dielectric waveguides

A perturbation and iterative perturbation analysis of linearly chirped quasi-periodic structures of mediumQfactor in planar dielectric waveguides has been formulated. This analysis can be used to calculate the diffraction efficiency and the angular field of view of a given linearly chirped grating structure, for a specific incident beam including the effect of higher orders of diffractions. The numerical example of aF = 10 , f = 10m.m,Lambda_{min} = 2.06, Lambda_{max} = 4.25and grating groove length = 15 μm is presented.     

CW performance of an InGaAs-GaAs-AlGaAs laterally-coupleddistributed feedback (LC-DFB) ridge laser diode

Single-mode distributed feedback (DFB) laser diodes typically require a two-step epitaxial growth or use of a corrugated substrate. We demonstrate InGaAs-GaAs-AlGaAs DFB lasers fabricated from a single epitaxial growth using lateral evanescent coupling of the optical field to a surface grating etched along the sides of the ridge. A CW threshold current of 25 mA and external quantum efficiency of 0.48 mW/mA per facet were measured for a 1 mm cavity length device with anti-reflection coated facets. Single-mode output powers as high as 11 mW per facet at 935 nm wavelength were attained. A coupling coefficient of at least 5.8 cm^-1 was calculated from the subthreshold spectrum taking into account the 2% residual facet reflectivity     

An evolutionary game theory–based security model in vehicular ad hoc networks

The word population is growing on a daily basis; consequently, the growth of commute and transport, developing efficient and intelligent transportation systems (ITS), has become one of the most popular requirements and the most significant attempts in modern urban areas containing large population. A key component of intelligent transportation systems is a vehicular ad hoc network. Devising internet‐based practical programs such as awareness of climatic conditions, geographical location, practical programs like on‐line payment services in the vehicular ad hoc network has led to safer driving, prevention of deadly accidents, transportation improvement, more welfare and convenience for passengers, and even offering more commercial opportunities. The special features of vehicular ad hoc network, such as intense activity, constantly‐changing topology, the vehicles' high speed, etc, will lead to challenges in gaining security. Therefore, providing vehicular ad hoc networks with security is of extreme importance in terms of users' anonymity, identification, and data privacy. In this paper, a security model is presented using a method based on evolutionary games. This method, in every vehicle, is applied as a node in the network while interacting with other vehicles; it aims at distinguishing some common attacks and defending against attackers. In this method, defending (honest) vehicles and attacking vehicles take part in an asymmetrical game; each vehicle aims at gaining the most utility and achieving its goals. The proposed method is simulated using various scenarios. The simulation results reveal that the proposed method is efficient and it reaches equilibrium and convergence at the end of the game in each scenario.     

Non-isothermal aging of a high-Zn-containing Al–Zn–Mg–Cu alloy: microstructure and mechanical properties

The non-isothermal aging behaviour of a newly developed Al–Zn–Mg–Cu alloy containing 17?wt-% Zn was investigated. Hardness and shear punch tests demonstrated that during non-isothermal aging, the mechanical properties of the alloy first increased and then decreased. The best properties were obtained in a sample which was non-isothermally aged upto 250°C with heating rate of 20°C?min^?1, due to the presence of η′/η (MgZn₂) phases. This was confirmed by differential scanning calorimetery. After homogenisation, residual eutectic phases remained at triple junctions or in a spherical form. During aging, these phases transformed into rodlike S (Al₂CuMg)-phase at 400°C, with sizes ranging from 50 to 250?nm. The precipitation sequence in this high-Zn alloy was similar to that for conventional Al–Zn–Mg–Cu alloys.     

Electrocatalytic activity of Pt nanoparticles supported on novel functionalized reduced graphene oxide-chitosan for methanol electrooxidation

Here, graphene oxide (GO) was synthesized by a modified Hummers’ method and was functionalized with 1,1′-dimethyl-4,4′-bipyridinium dichloride (MV) accompanied by chitosan (CH) to prepare a novel MV-RGO-CH support. Pt/MV-RGO-CH catalyst was prepared by immobilization of the Pt nanoparticles on MV-RGO-CH support. The microstructure and morphology of the prepared catalyst was characterized by transmission electron microscopy and X-ray powder diffraction analysis. The electrocatalytic activity of Pt/MV-RGO-CH catalyst was investigated for methanol electrooxidation through cyclic voltammetry (CV), CO_ads stripping voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS) techniques. The effects of some experimental factors for methanol electrooxidation such as methanol concentration, scan rate and temperature were studied at the prepared catalyst. Durability of the catalyst was also investigated. Comparing the catalytic activity of the Pt/MV-RGO-CH nanocatalyst with Pt/CH and Pt/MV-RGO catalysts indicated that Pt/MV-RGO-CH has a very good catalytic activity for methanol electrooxidation.     

A New Image Mining Approach for Detecting Micro-Calcification in Digital Mammograms

Although mammography is typically the best method to detect breast cancer, it does not recognize 3–20% of the cancer cases. Mammography has established itself as the most efficient technique for detecting tiny cancerous tumor and micro-calcifications are the most difficult to detect since they are very small (0.1–1.0 mm) and they are almost contrasted against the images background. The main purpose of this paper is to provide a new method for the automatic diagnosis of micro-calcification in digital mammograms. It is based on image mining, and the results show 97.35% accuracy, which is improved than the previous works. Tests are based on the standard images data corpus, MIAS. The practical result of this research is registered as an invention in the Patents and Industrial Property Registration Organization numbered as 83119.