Optimistic Selection of Cluster Heads Based on Facility Location Problem in Cluster-Based Routing Protocols

Cluster-based routing protocols are one of the most favorable approaches for energy management in wireless sensor networks. The selection of the best cluster heads (CHs), as well as the formation of optimal clusters, is an NP-hard problem. The present study proposes an optimal solution for CHs selection to generate a network topology with optimized network performance. The problem is formulated as facility location problem and a linear programming model is used to solve the optimization problem. Results of analysis o the network simulator (NS2) indicate that applying this method in cluster-based routing protocols prolongs 16 % of the network lifetime, increases 15.5 % of data transmission and improves 5.5 % of throughput, as compared to the results of current heuristic methods such as LEACH, DEEC and EDFCM protocols.     

Elastomeric Fibrous Hybrid Scaffold Supports In Vitro and In Vivo Tissue Formation

Biomimetic materials with biomechanical properties resembling those of native tissues while providing an environment for cell growth and tissue formation, are vital for tissue engineering (TE). Mechanical anisotropy is an important property of native cardiovascular tissues and directly influences tissue function. This study reports fabrication of anisotropic cell‐seeded constructs while retaining control over the construct's architecture and distribution of cells. Newly synthesized poly‐4‐hydroxybutyrate (P4HB) is fabricated with a dry spinning technique to create anelastomeric fibrous scaffold that allows control of fiber diameter, porosity, and rate ofdegradation. To allow cell and tissue ingrowth, hybrid scaffolds with mesenchymalstem cells (MSCs) encapsulated in a photocrosslinkable hydrogel were developed. Culturing the cellularized scaffolds in a cyclic stretch/flexure bioreactor resulted in tissue formation and confirmed the scaffold's performance under mechanical stimulation. In vivo experiments showed that the hybrid scaffold is capable of withstanding physiological pressures when implanted as a patch in the pulmonary artery. Aligned tissue formation occurred on the scaffold luminal surface without macroscopic thrombus formation. This combination of a novel, anisotropic fibrous scaffold and a tunable native‐like hydrogel for cellular encapsulation promoted formation of 3D tissue and provides a biologically functional composite scaffold for soft‐tissue engineering applications.     

Evaluation of antioxidant activities of Iranian sumac (R. coriaria L.) fruit and spice extracts with different solvents

The antioxidant capacity and phenolic content of three sumac (Rhus coriaria L.) samples, including brown sumac fruit, brown sumac powder and red sumac powder were investigated in the present study. Methanol, ethanol, distilled water, and a mixture of methanol and ethanol (1:1) were used as solvent systems. Antioxidant activities of extracts were screened using 1,1-diphenyl-2-picrylhydrazyl DPPH radical scavenging method. Phenolic content was determined through Folin–Ciocaltaeu procedure. The efficiency of the solvents used to extract phenols from the samples varied considerably. The phenolic content of brown sumac powder ranged from 2.906 to 2.997 gallic acid equivalents/100 g (GAE/100 g), while that of the brown sumac fruit was 2.438–2.529 GAE/100 g, and that of the red sumac powder was 2.172–2.263 GAE/100 g. Findings indicated that water extracts of sumac have effective antioxidant and radical scavenging activities as compared to other extracts.     

Numerical simulation of transient heat transfer for tomato paste in semi rigid aluminum container

In this study, numerical model of heat transfer for tomato paste in semi-rigid aluminum container was developed by Fluent software 6.3.26. Grid independence was recognized. The impact of head space (air and water -vapor) and buoyancy force on heat transfer were investigated. Simulation results showed slowest heating zone (SHZ) located in (?11.676?<?X?<??10.738, 0.183?<?Y?<?1.269 and 4.417?<?Z?<?5.560) for model with air head space and in (?11.166?<?X?<??11.370, 0.762?<?Y?<?1.21 and 5.480?<?Z?<?5.506) for model with water–vapor head space in Cartesian system coordinate. A thermocouple was connected to container at (0, 0, 10 cartesian system coordinate) to get experimental data during process. Comparing temperatures of experimental model and predicted model (with head space) illustrated no significant difference (p?<?0.05).     

Hydrogen desorption properties of MgH2-TiCr1.2Fe0.6 nanocomposite prepared by high-energy mechanical alloying

In the present work, high-energy mechanical alloying (MA) was employed to synthesize a nanostructured magnesium-based composite for hydrogen storage. The preparation of the composite material with composition of MgH₂-5 at% (TiCr_1.2Fe_0.6) was performed by co-milling of commercial available MgH₂ powder with the body-centered cubic (bcc) alloy either in the form of Ti-Cr-Fe powder mixture with the proper mass fraction (sample A) or prealloyed TiCr_1.2Fe_0.6 powder (sample B). The prealloyed powder with an average crystallite size of 14 nm and particle size of 384 nm was prepared by the mechanical alloying process. It is shown that the addition of the Ti-based bcc alloy to magnesium hydride yields a finer particle size and grain structure after mechanical alloying. As a result, the desorption temperature of mechanically activated MgH₂ for 4 h decreased from 327 °C to 262 °C for sample A and 241 °C for sample B. A high dehydrogenation capacity (∼5 wt%) at 300 °C is also obtained. The effect of the Ti-based alloy on improvement of the dehydrogenation is discussed.     

Production of surface-active sophorolipid biosurfactant and crude oil degradability by novel Rhodotorula mucilaginosa strain SKF2

Biosurfactants are produced by important types of microorganisms such as bacteria, yeast, and filamentous fungi and have been used in a variety of industries. Among the 15 crude oil-degrading fungi, the two molds and one yeast were identified by 18S rDNA sequences as Mucor circinelloides strain SKMC, Fusarium fujikuroi strain DB2, and Rhodotorula mucilaginosa strain SKF2. These strains were isolated from crude oil–contaminated soil, diesel oil–contaminated soil, and activated sludge in the Oil Refinery Plant in Isfahan, Iran, respectively. The yeast strain was identified as a novel crude oil–degrading and biosurfactant-producing fungi in the presence of (1% v/v) Iranian light crude oil in the minimal salt medium (MSM). The highest amount of the dry weight of produced biosurfactant was measured at 6.2 g L⁻¹. Chemical nature of produced biosurfactant was determined as a surface-active sophorolipid biosurfactant compound by thin-layer chromatography, Fourier transform infra-red spectroscopy, and gas chromatography–mass spectrometry (GC–MS) analysis. The residual hydrocarbons in the MSM were analyzed by GC–MS, and it was shown that octadecane and docosane were eliminated by this novel strain completely.     

Electroactive polythiophene/polystyrene bottlebrushes as morphology compatibilizers in photovoltaic systems

Poly(3‐thiophene ethanol) (P3ThEt)‐graft‐polystyrene (PSt) bottlebrushes were synthesized and applied in active layers of poly(3‐hexylthiophene) (P3HT):phenyl‐C71‐butyric acid methyl ester (PC71BM) solar cells as morphology compatibilizers. In the presence of 15 wt% of P3ThEt‐graft‐PSt bottlebrush compatibilizers, the P3HT crystallite dimensions (D₍₁₀₀₎ = 45.67 nm and D₍₀₂₀₎ = 30.12 nm) and R_mean (38.96 nm) of PCBM clusters were the largest and the layer spacings were all the smallest (d₍₁₀₀₎ = 1.054 nm, d₍₀₂₀₎ = 0.301 nm and d_(PCBM) = 0.406 nm). These dimensional properties led to better hole (1.9 × 10^?3 cm² V^?1 s^?1) and electron (1.2 × 10^?2 cm² V^?1 s^?1) mobilities. The content of bottlebrushes was optimized at 15 wt%, and thereby the best photovoltaic results including the maximum cell efficiency of 5.37% were obtained for this turning point (12.75 mA cm^?2, 61%, 0.69 V). On exceeding the optimum weight percentage, all photovoltaic parameters decreased markedly and reached even less than that of pristine devices (1.92% versus 2.24%). After an optimum weight percentage of compatibilizers, further enhancement in bottlebrush content in active layers saturated and finally oversaturated the system and, consequently, the cell parameters significantly decreased. Accumulation of bottlebrushes in interfaces and donor/acceptor phases ruined the system function even with large and packed P3HT crystallites and PC71BM clusters. © 2019 Society of Chemical Industry     

Investigation of Magnesium Incorporation within Gelatin/Calcium Phosphate Nanocomposite Scaffold for Bone Tissue Engineering

In this study, diffusional method was used to prepare a calcium phosphate/gelatin nanocomposite as a scaffold for bone tissue repair. Incorporation of magnesium (Mg) into mineral phase of the scaffold was also investigated. Addition of Mg ions to the synthesis process caused formation of magnesium phosphate (MgP) and hydroxyapatite (HAp). However, analyses data for the sample lacking Mg showed that the mineral formed within GEL had a low crystalline nature, consisting of HAp and octacalcium phosphate (OCP). With addition of Mg within the structure of precipitated minerals, morphology of minerals was dramatically changed toward being irregular and less ordered.     

Colloidal synthesis of copper nanoparticles in a two-phase liquid-liquid system

Synthesis of copper nanoparticles in a two-phase, toluene-water system was investigated. The synthesis involves a transfer of metal cations from the aqueous phase to the toluene phase through the use of tetraoctylammonium bromide, a phase transfer reagent. Subsequently, the metal cations were reduced using sodium borohydride in the presence of oleylamine, a stabilizing ligand. Due to the high tendency of copper to oxidize in air, the syntheses and post-synthesis treatments were carried out in an inert atmosphere, N₂. Non-agglomerated, generally spherical, copper nanoparticles with a mean size of 6.06 nm were successfully made using the technique. By analyzing the lattice d spacing of HRTEM images, the crystal structure of the particles was found to be FCC. The expected plasmon resonance peak for copper, 570 nm, was missing from UV/Vis spectroscopy analysis; this has been attributed to quenching due to residual CuBr.