Styrene butadiene co-polymer based conducting polymer composite as an effective corrosion protective coating

Electroactive conducting polymer composite coatings of polyaniline (PANI) are electrosynthesized on styrene–butadiene rubber (SBR) coated stainless steel electrode by potentiostatic method using aqueous H₂SO₄ as supporting electrolyte. The protective behaviour of these coatings in different corrosion media (3.5% NaCl and 0.5 M HCl) is investigated using Tafel polarization curves, open circuit potential measurements and electrochemical impedance spectroscopy. The results reveal that SBR/PANI composite coating is much better in corrosion protection than simple PANI coating. The corrosion potential of composite films shifts to more noble values indicating that SBR/PANI composite coating act as an effective corrosion protective layer.     

Effect of Tio2 Nanoparticles on the Antibacterial and Physical Properties of Low-Density Polyethylene Film

In this study, TiO₂ nanoparticles were incorporated into low-density polyethylene by melt blending. Morphological properties and dispersion behavior of TiO₂ nanocomposite were characterized through field emission scanning electron microscope, X-ray diffraction, and Fourier transform infrared spectroscopy. Thermal stability of the nanocomposites was determined by thermogravimetric analysis. Moreover, the mechanical properties of nanocomposites were determined. Antimicrobial activity of TiO₂ nanocomposites was investigated by in vitro test. Dispersion of the nanoparticles was good in nanocomposites_. According to thermogravimetric analysis, incorporation of TiO₂ nanoparticles into low-density polyethylene enhanced the thermal stability. Mechanical properties of nanocomposites were improved by TiO₂ nanoparticles. Results showed that the antibacterial effect of low-density polyethylene –TiO₂ nanocomposite was significantly enhanced by TiO₂nanoparticles (p?2 nanoparticles not only can improve the properties of low-density polyethylene but they also have the potential to be used as an active food packaging film.     

Synthesis,Characterization and Antibacterial Properties of Nano-Porous Zn3(BTC)2·12H2O upon Silk Yarn Under Ultrasound Irradiation

A porous coordination polymer, Zn₃(BTC)₂·12H₂O (Zn-BTC) upon silk yarn, has been synthesized under ultrasound irradiation of identical reaction mixtures of Zn(II) and H₃BTC (BTC = 1,3,5-benzenetricarboxylate). Effects of temperature, sequential dipping steps and sonication on the growth of Zn-BTC upon silk yarn were investigated. These systems depicted a decrease in the particles size accompanying a decrease in the sequential dipping steps. Results showed a decrease in the particles size as decreasing frequency of ultrasound irradiation. The antimicrobial activity of Zn-BTC upon fiber was tested against the Gram positive strain Micrococcus sp. and Gram negative bacterial strain Escherichia coli. The samples were characterized with X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy spectra and scanning electron microscopy. XRPD analyses indicated that the prepared Zn-BTC nanostructures on silk fibers were crystalline.     

User cooperation to mitigate the jamming in OFDMA networks

In this paper, jamming and anti-jamming in a time slotted orthogonal frequency division multiple access (OFDMA) are investigated. The users of the network cooperate to mitigate the jamming effect. Interactions among the network users and the jammer are modeled by a mixed integer non-cooperative generalized game which is a NP-hard problem. To relax the problem, a new algorithm is proposed based on channel state information (CSI) to determine the transmission channels and the partners of users in the network. To solve the proposed game, an optimization problem is solved for each player considering the best response of the other player. Another generalized game is proposed to model the cooperation among users of the network. The latter game is transformed to an equivalent Quasi Variational Inequality (QVI). Then, a new gradient based algorithm is proposed by utilizing the Karush-Kuhn-Tucker (KKT) conditions to find the solution of the equivalent QVI. Then, solving the latter game and substituting the best related response, the solution of the former generalized game is also obtained. The convergence of the proposed algorithms, and the uniqueness related to the solution of the both generalized games are proven. Finally, the simulation results confirm the effectiveness of the proposed approach.

     

A study of the potential of using the Earth to air heat exchanger for cooling and heating of residential buildings in Iraq

The Earth to air heat exchanger (EAHE) is an effective passive cooling and heating system for buildings. This paper studied numerically the potential for reduction in energy consumption for cooling and heating loads for a residence equipped with an EAHE system in the climate of Nasiriya city, which is located in southern Iraq and at 31.7°N and 45.8°E, latitude and longitude, respectively. Also, this paper presents a study about the thermal performance of three types of EAHE systems, system 1, consisting of one layer of EAHE and buried at an available area of house garden with 3‐m depth, system 2, at the same site of system 1, but with two layers of EAHE at two depths, 3 and 4 m, and finally, system 3, buried along the area of the house at a depth of 3 m. First, the built numerical model was validated against experimental results, and the results of the comparison showed good agreement. The electricity consumption for cooling and heating of the house is calculated with and without the EAHE system. The results showed that with using EAHE, there is a considerable saving in energy and saving in the cost of electricity consumption, which reached 376 329 IQD ($301.11) over 1 year for system 2.     

Design of a novel microstrip four-channel diplexer for multi-channel telecommunication systems

Telecommunication Systems - This paper presents a novel microstrip quad-channel diplexer. The introduced diplexer operates at close resonance frequencies of 1.68 GHz, 1.9 GHz,...     

Effects of lead toxicity on the total chlorophyll content and growth changes of the aquatic plant Ceratophyllum demersum L.

This paper reports results of a laboratory-scale experiment conducted to determine the effects of different initial concentrations of a toxic heavy trace metal (lead) on the total chlorophyll (a + b) content of aquatic plant tissues Ceratophyllum demersum L., and also to monitor the visible growth changes during the experiment under different lead concentrations (2, 4 and 6 mg/L), as well as in control plants (without any addition of lead nitrate solution). Lead concentrations in water and plant samples were determined using AAS, where the total chlorophyll content in plant leaf tissues was measured every 15 days during the experimental period using a UV/VIS Spectrophotometer, Model 160A, Shimadzu, with wavelengths of 665 and 649 nm. The results showed that the content of total chlorophyll decreased noticeably, with increasing initial concentrations of lead throughout the exposure time. Decreases in total chlorophyll content in the tissues of C. demersum over the period of the experiment were accompanied by different morphological changes in the plants, depending on the initial lead concentration and exposure duration. These changes in morphology and growth affected the number and length of branches, the number of leaves and the number of leaflets.     

A Systematic Molecular Dynamics Investigation on the Graphene Polymer Nanocomposites for Bulletproofing

In modern physics and fabrication technology, simulation of projectile and target collision is vital to improve design in some critical applications, like; bulletproofing and medical applications. Graphene, the most prominent member of two dimensional materials presents ultrahigh tensile strength and stiffness. Moreover, polydimethylsiloxane (PDMS) is one of the most important elastomeric materials with a high extensive application area, ranging from medical, fabric, and interface material. In this work we considered graphene/PDMS structures to explore the bullet resistance of resulting nanocomposites. To this aim, extensive molecular dynamic simulations were carried out to identify the penetration of bullet through the graphene and PDMS composite structures. In this paper, we simulate the impact of a diamond bullet with different velocities on the composites made of single- or bi-layer graphene placed in different positions of PDMS polymers. The underlying mechanism concerning how the PDMS improves the resistance of graphene against impact loading is discussed. We discuss that with the same content of graphene, placing the graphene in between the PDMS result in enhanced bullet resistance. This work comparatively examines the enhancement in design of polymer nanocomposites to improve their bulletproofing response and the obtained results may serve as valuable guide for future experimental and theoretical studies.     

Integrated Freestanding Two‐dimensional Transition Metal Dichalcogenides

This paper reports on the integration of freestanding transition metal dichalcogenides (TMDs). Monolayer (1‐L) MoS₂, WS₂, and WSe₂ as representative TMDs are transferred on ZnO nanorods (NRs), used here as nanostructured substrates. The photoluminescence (PL) spectra of 1‐L TMDs on NRs show a giant PL intensity enhancement, compared with those of 1‐L TMDs on SiO₂. The strong increases in Raman and PL intensities, along with the characteristic peak shifts, confirm the absence of stress in the TMDs on NRs. In depth analysis of the PL emission also reveals that the ratio between the exciton and trion peak intensity is almost not modified after transfer. The latter shows that the effect of charge transfer between the 1‐L TMDs and ZnO NRs is here negligible. Furthermore, confocal PL and Raman spectroscopy reveal a fairly consistent distribution of PL and Raman intensities. These observations are in agreement with a very limited points contact between the support and the 1‐L TMDs. The entire process reported here is scalable and may pave the way for the development of very efficient ultrathin optoelectronics.