Sonochemical synthesis and characterization of zinc tungstate nanoparticles and investigation of its photocatalyst application

Zinc tungstate nanoparticles were synthesized via a sonochemical method based on the reaction between zinc (II) nitrate hexahydrate and sodium tungstate dihydrate in water. The structural, morphological and optical properties of as-obtained products were characterized by techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis, and ultraviolet–visible spectroscopy. The samples indicated a ferromagnetic behavior, as evidenced by using vibrating sample magnetometer at room temperature. To evaluate the catalytic properties of nanocrystalline zinc tungstate, the photocatalytic degradation of methyl orange under ultraviolet light irradiation was carried out.     

Poly (butylene adipate-co-butylene terephthalate) nanoparticles prepared by electrospraying technique for docetaxel delivery in ovarian cancer induced mice

Objective: Ovarian cancer is still a major cause of morbidity and mortality. Docetaxel (DTX) is one of the most notable cytotoxic agents for treatment of ovarian cancer. However, its side effects proposed considerable problems to the patients.

Significance: Polymeric nanoparticles (NPs) of poly (butylene adipate-co-butylene terephthalate) (Ecoflex^®), a biodegradable and biocompatible polymer, were prepared for the first time by the upgradeable electrospraying technique.

Methods: The formulation and procedure variables were optimized using Design Expert software, and effect of each variable on particle size, particle size distribution, drug entrapment efficiency, and drug release of the NPs were evaluated. Then, in vitro cytotoxicity, cellular uptake, X-ray diffraction pattern, and morphological characteristics of the optimized NPs were evaluated. Finally, in vivo efficacy of the DTX-loaded NPs was evaluated on tumor bearing nude mice.

Results: The optimum condition for production of NPs included voltage of 20?kV, 12?cm distance between electrodes, feeding rate of 1?mL/hr, polymer to drug ratio of 3:1, 1 w/v% of Pluronic-F127 and dichloromethane to dimethyl formamide ratio of 2.7:1. Fluorescent microscopy test showed the NPs were successfully up-taken by ovarian cancer cells. In vitro cytotoxicity test confirmed no cytotoxic effect caused by blank NPs, while cell viability of the DTX loaded NPs was significantly lower than the free DTX (p?p?Conclusion: The Ecoflex^® NPs could potentially provide a suitable alternative for currently available formulations of DTX.     

Local behavior of column-tree connections with considering bolt-hole clearance and bolt pretension effects

In this paper, effects of bolt-hole clearance and bolt pretension level on seismic performance of column-tree moment resisting frames with reduced beam section have been investigated. In a typical constructional environment, manufacturing tolerances and field situations cause inappropriate positioning of bolts in their corresponding holes in bolted connections, so bolt-hole diameter increases by incorrect methods like acetylene gas cutting method. On the other hand, nonlinear local behavior of the connection elements and effects of dynamic friction during the process of applying the bolt pretension cause wrong evaluation of bolt pretension level. In order to investigate these problems, models of column-tree connections with various bolt-hole clearances and bolt pretension levels subjected to cyclic loading were developed and analyzed with 3D FEM and their hysteresis curves were obtained and evaluated. Results show that bolt-hole clearance can reduce the flexural capacity of column-tree connections especially along with reduction in the bolt pretension level while interstory drift angle increases during inelastic cycles.     

Monitoring dependent process steps using robust cause‐selecting control charts

Cause‐selecting control charts are believed to be invaluable for monitoring and diagnosing multistage processes where the output quality of some stages is significantly impacted by the output quality of preceding stages. To establish a relationship between input and output variables, a standard procedure uses historical data, which are often prone to hold outliers. The presence of outliers tends to decrease the effectiveness of monitoring procedures because the regression model is distorted and the control limits become stretched. To dampen the negative repercussions of outliers, robust fitting techniques based on M‐estimators are implemented instead of the ordinary least‐squares method and two robust monitoring approaches are presented. An example is given to illustrate the application and performance of the proposed control charts. Furthermore, a simulation‐based study is included to investigate and compare the average run length of robust and non‐robust schemes. The results reveal that the robust procedure far outperforms the non‐robust counterpart due to its prompt detection of out‐of‐control conditions when outliers exist. Copyright © 2009 John Wiley & Sons, Ltd.     

Proteolysis and textural properties of low‐fat ultrafiltered Feta cheese as influenced by maltodextrin

Maltodextrin was used as a fat replacer in low‐fat ultrafiltered cheese. Fat was replaced with 25% maltodextrin milk solution (w/w) in cheese at 15 and 50% (w/w). The chemical, rheological and sensory properties as well as the microstructure of the cheese samples were evaluated after storage for 2 months at 8 °C. Maltodextrin affected the chemical (pH, dry matter, fat, water‐soluble nitrogen to total nitrogen, nonprotein nitrogen to total nitrogen, total free amino acid) and rheological (mean relaxation time) properties, as well as the microstructure. In general, based on textural properties, sensory evaluation and economic aspects, the 50%‐fat‐reduced sample was selected as the best treatment.     

Optimal operation management of fuel cell/wind/photovoltaic power sources connected to distribution networks

In this paper a new multiobjective modified honey bee mating optimization (MHBMO) algorithm is presented to investigate the distribution feeder reconfiguration (DFR) problem considering renewable energy sources (RESs) (photovoltaics, fuel cell and wind energy) connected to the distribution network. The objective functions of the problem to be minimized are the electrical active power losses, the voltage deviations, the total electrical energy costs and the total emissions of RESs and substations. During the optimization process, the proposed algorithm finds a set of non-dominated (Pareto) optimal solutions which are stored in an external memory called repository. Since the objective functions investigated are not the same, a fuzzy clustering algorithm is utilized to handle the size of the repository in the specified limits. Moreover, a fuzzy-based decision maker is adopted to select the ‘best’ compromised solution among the non-dominated optimal solutions of multiobjective optimization problem. In order to see the feasibility and effectiveness of the proposed algorithm, two standard distribution test systems are used as case studies.     

Semiconductor‐assisted self‐cleaning polymeric fibers based on zinc oxide nanoparticles

Self‐cleaning polymeric fibers have been successfully prepared by depositing ZnO nanoparticle onto wool and polyacrylonitrile (PAN) fibers with good compatibility and significant photocatalytic self‐cleaning activity using the sol‐gel process at ambient temperature. scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X‐ray diffraction, Brunauer‐Emmett‐Teller surface area analysis, and thermogravimetric analysis have been adopted as the characterization techniques. Transmission electron microscopy studies revealed presence of zinc oxide nanoparticles with 10–15 nm in size. Brunauer‐Emmett‐Teller measurement showed surface area of 48 m²/g for the ZnO nanoparticles. Photocatalytic activity of the self‐cleaning materials were tested by measuring the photo‐assisted degradation of methylene blue (MB) and eosin yellowish (EY) under ultraviolet‐visible illumination. The results indicate that both of the ZnO‐coated polyacrylonitrile and ZnO‐coated wool fibers acquire photocatalytic activity toward dyes degradation. The photocatalytic activity of the treated fibers is maintained upon several numbers of photodegradation cycles. This facile and cheap preparation technique can be also applied to new polymeric fabrics to produce self‐cleaning materials for industrial application. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

On the mechanism of methanol synthesis and the water-gas shift reaction on ZnO

Zinc oxide catalyses both methanol synthesis and the forward and ‘everse water-gas shift reaction (f- and r- WGSR). Copper also catalyses both reactions, but at lower temperatures than ZnO. Presently the combination of Cu and ZnO stabilized by Al₂O₃ is the preferred catalyst for methanol synthesis and for the f- and r- WGSR. On Cu, the mechanism of methanol synthesis is by hydrogenation of an adsorbed bidentate formate [1] (the most stable adsorbed species in methanol synthesis), while the f- and r- WGSR proceeds by a redox mechanism. The f-WGSR proceeds by H₂O oxidizing the Cu and CO, reducing the adsorbed oxide and the r-WGSR proceeds by CO₂ oxidising the Cu and H₂, reducing it [2–5]. Here we show that the mechanisms of both reactions are subtly different on ZnO. While methanol is shown to be formed on ZnO through a formate intermediate, it is a monodentate formate species which is the intermediate; the f- and r-WGS reactions also proceed through a formate – a bidentate formate - in sharp contrast to the mechanism on Cu.     

Preparation and investigation of structural,magnetic, and microwave absorption properties of aluminum‐doped strontium ferrite/MWCNT/polyaniline nanocomposite at KU‐band frequency

Aluminum‐doped strontium hexaferrite nanoparticle SrAl_1.3Fe_10.7O₁₉ was prepared by sol–gel method and polyaniline (PANi) multiphase magnetic nanocomposite SrAl_1.3Fe_10.7O₁₉/MWCNT/PANi was synthesized through a sonochemical method by in situ polymerization. The morphology, structure, and magnetic properties of the nanocomposites are investigated by field emission scanning electron microscopy, X‐ray powder diffraction, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. The electromagnetic interference shielding efficiency was evaluated in the KU‐band (12.4–18 GHz). The reflection loss (RL) value showed that the composites have an excellent absorbing property in the KU‐band, minimum ?24.93 dB at 16.40 GHz with a bandwidth of 2.81 GHz (shielding effectiveness up to 10 dB) at a matching thickness 6.5 mm. The RL value of the SrAl_1.3Fe_10.7O₁₉/MWCNT nanocomposite was ?15.92 dB at 15.84 GHz with a bandwidth of 1.66 GHz (with a shielding effectiveness up to 10 dB). These results disclose the remarkable microwave shielding ability of SrAl_1.3Fe_10.7O₁₉/MWCNT/PANi in KU‐band due to the interactive effect of the three components. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45135.