Chemical composition,oral toxicity and antimicrobial activity of Iranian propolis

Propolis is a resinous natural hive product derived from plant exudates collected by honeybees. Due to biological and pharmacological activities, it has been extensively used in folk medicine. The present study was designed to investigate the chemical composition, subchronic toxicity, antimicrobial activity of Iranian propolis ethanolic extract, which has not been studied previously. One hundred and nine compounds were identified by gas chromatography–mass spectrometry analysis. Forty-five days subchronic toxicity of oral propolis extract was investigated in male rats. During the study no significant behavioral and clinical toxicity has been seen in animals however, hematologic, blood biochemistry and histopathologic data studies exhibited some significant differences between the groups. The ethanolic extract of propolis inhibited the growth of all examined microorganisms including bacteria and fungi with the highest antimicrobial activity against Gram-positive bacteria such as Staphylococcus aureus and Staphylococcus epidermidis.     

Multi-Objective Optimization-Simulation for Reliability-Based Inter-Basin Water Allocation

A simulation-optimization framework is presented for reliability-based optimal sizing, operation, and water allocation in the Bashar-to-Zohreh inter-basin water transfer project. The problem was formulated as a mixed integer nonlinear program (MINLP), for which two solution approaches were tested, including gradient-based nonlinear programming and simulation-optimization (SO). The SO framework linked the water evaluation and planning system (WEAP) simulation module, benefiting from fast, single-period linear programming, to the multi-objective particle swarm optimization (MOPSO) for multiperiod optimization. The objective functions were minimizing the sizes of the project’s infrastructures and maximizing the reliability of supplying water to agricultural lands. The combination of nonlinear programming and the branch-and-bound algorithm was not able to solve the resulting MINLP. The results of the MOPSO-WEAP framework indicated that the project can supply water for land development in the Dehdasht and Choram agricultural plains, located in the less developed Kohgiluye and Boyer-Ahmad Province of Iran at an acceptable reliability level. For example, for one of the Pareto solutions found corresponding to maximum land development (30,000 ha), an average volume of 237 million cubic meter (MCM) is transferred annually at a 73.2% reliability level with average sizes of water transfer and storage elements. Further, design-operation and hydropower scenarios were also evaluated, and the Pareto solutions were obtained.     

Development of ZrO2‐MgO nanocomposite powders by the modified sol‐gel method

The ZrO₂‐MgO nanocomposites were synthesized using a new sol‐gel method with sucrose and tartaric acid as a gel agent. The samples were characterized by thermal analysis (TG/DTA), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray mapping (EDX mapping), and Ultraviolet‐visible spectroscopy (UV‐vis). The results showed that the cubic phase of ZrO₂‐MgO was formed in the presence of both gel agents. The average particle size of the samples synthesized with sucrose was lower (30 nm) than that of tartaric acid (50 nm). Finally, the formation mechanism and the optical properties of zirconia‐magnesia have been discussed.     

In vitro bactericidal effect of ultrasonically sol–gel-coated novel CuO/TiO<Subscript>2</Subscript>/PEG/cotton nanocomposite for wound care

Protection against bacterial contamination remains a demand for healthcare textiles such as wound dressings to reduce or eliminate hospital-acquired infections related to antibiotic-resistant bacteria. We report herein a simple and straightforward in situ approach to deposit copper oxide and titanium oxide nanoparticles onto cotton fabric using a sonochemical-mediated sol–gel method. Modification of the cotton surface was achieved by incorporation of citric acid (CA) and polyethylene glycol (PEG) to improve the attachment of the nanoparticles and reduce the attachment of bacteria to the cotton surface, respectively. The resultant cotton fabric was used against Escherichia coli as a Gram-negative bacterium and Staphylococcus aureus as a Gram-positive bacterium in dark condition as an in vitro model for treatment of bacterial wound infection. The effects of different treatment parameters including duration and frequency of ultrasonic irradiation, surface modification with PEG and/or CA, and cotton chemical composition with different metal oxide molar ratios on the antibacterial activity of the treated cotton fabric were studied. All treated cotton fabrics showed antibacterial activity, with higher efficiency for those coated with CuO or CuO/TiO₂ (1:1 molar ratio) among the single metal oxide and composite-modified cotton fibers, respectively. Our results show that such functionalized cotton fibers could actively fight the spread of bacterial infections by preventing bacterial adhesion, enabling more efficient bonding, and ultrasonically promoting generation of nanoparticles and their strong adhesion to the fabric surface.     

Assessment of the cutaneous wound healing efficiency of acidic,neutral and alkaline bacterial cellulose membrane in rat

Recent research was conducted to evaluate the healing efficiency of bacterial cellulose (BC) as a wound dressing in different pHs and its possibility of being a smart wound dressing that can indicate pHs. BC was produced by environmentally isolated bacterial strains. After washing the best achieved BC, it was floated in normal saline with different pHs with phenol red used as a pH indicator. Finally the wound healing effects of the acidic, neutral and alkaline BC membranes were evaluated in rat cutaneous wounds. Results showed that one of the isolates which its partial 16srRNA genome had 95% similarity with Gluconacetobacter intermedius, had the thickest layer. The microscopic and macroscopic evaluations showed that the acidic BC had the best healing activity. Although the color of the films remained unchanged during the experiments because they were transparent and thin, these changes could not be easily seen. This suggests the use of thicker films such as the ones which are cross linked with some materials (e.g., sterile gauze). In conclusion the pH can affect the healing ability of natural BC and acidic pH had the best wound healing efficiency. In future it is better to use the acidic BC instead of natural one for different wound healing purposes.     

Influences of initiator addition methods in suspension polymerization of vinyl chloride on poly(vinyl chloride) particles properties

Vinyl chloride suspension polymerization was carried out in a pilot‐scale reactor to study the effects of different methods of initiator addition on poly(vinyl chloride) (PVC) resin properties. The experiments used different arrangements for adding the initiator to the reactor, whereas other reaction conditions were the same: (i) initiator was added to the continuous aqueous phase and then monomer was dispersed in it (conventional method); (ii) initiator was predissolved in monomer before dispersing in the continuous aqueous phase; and (iii) suspending agents along with initiator were added to the monomer before polymerization. The PVC resin prepared by method of (i) had a higher monomer conversion and a higher Sauter mean diameter of grains with a narrow particle size distribution comparable to that of PVC resins by other methods. Scanning electron microscopy showed more uniform particles and fused primary particles in the grains, which confirms lower porosity and lower cold plasticizer absorption (CPA) for PVC grains produced by procedure of (ii). The results showed that when the suspending agents were also predispersed in monomer along with initiator (iii), CPA increases dramatically due to internal porosity of the grains. Simultaneously, a marked decrease in Sauter mean diameter was apparent. Scanning electron microscopy micrographs show that primary particles in the interior of PVC grains prepared by the latter method are looser, and there is more free volume between primary particles resulting the high internal porosity and consequently higher CPA. Mercury porosimetry analysis also confirms these results. K value as a molecular weight characteristic for all methods was the same . J. VINYL ADDIT. TECHNOL., 24:116–123, 2018. © 2016 Society of Plastics Engineers     

Anisotropic membranes from electrospun mats of sulfonated/nonsulfonated poly (ether ketone)s containing ion-rich paths as proton exchange membranes

Anisotropic proton exchange membranes composed of five layers with different contents of ionic groups across the membrane were prepared by simultaneous electrospinning of sulfonated and nonsulfonated poly(ether ketone) (PEK)s. To prepare nonporous and defect- free membranes from electrospun mats, nonsulfonated fibers as hydrophobic part of the membrane were melted by hot-pressing so that covered sulfonated fibers (hydrophilic part). Prepared membranes showed better thermal and dimensional stability compared to Nafion 115. Proton conductivity of membranes was comparable with Nafion especially at higher temperatures. Water uptake of prepared membranes and mechanical strength of them were in an acceptable range. The results showed that the difference between sulfonated PEK fibers in surface and center of the membranes affect proton conductivity and mechanical properties of the membranes.     

Detection of axial crack in the bend region of a pipe by high frequency electromagnetic waves

High frequency electromagnetic guided waves are used to detect axial narrow slit or crack in bend-section of the U-shape pipe. In the previous studies performed by the authors, electromagnetic waves (EM-waves) of TM₀₁- and TE₁₁-modes have used to detect circumferential and axial crack in straight section of a pipe, appropriately. In this paper to show potential of this technique for detection of any shape of piping system, especially bend-section of the steam generator (SG) and feeder pipe of pressurized water reactor (PWR), axial crack in bend-section is investigated. Due to axial orientation of the crack, TE₁₁-mode, a suitable mode for detection of axial crack is implied for this purpose. To excite TE₁₁-mode in the test pipe, microwave signals generated by the network analyzer, are sent to the inspected pipe by a coaxial line and a mode converter. Presence of the crack causes change in the reflection coefficient of the reflected signals from the crack. The behavior of the crack characteristic signals as a function of time is studied to estimate time of flight of the reflected wave and consequently crack position. Suitable frequency range is chosen in order to generate only TE₁₁-mode in the test pipe. To show effect of frequency range of the electromagnetic waves to the crack, crack positions are also evaluated for several smaller frequency ranges. Two crack positions were examined and comparisons of measurement results with theoretical calculations indicate that the microwave guided waves technique has high capability to detect defect in bend-section of a piping systems.