Synthesis and characterization of new thermally stable poly(ester‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic dihydroxy compounds

A series of new alternating aromatic poly(ester‐imide)s were prepared by the polycondensation of the preformed imide ring‐containing diacids, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A model compound (3) was also prepared by the reaction of 2b with phenol, its synthesis permitting an optimization of polymerization conditions. Poly(ester‐imides) were fully characterized by FTIR, UV‐vis and NMR spectroscopy. Both biphenylene‐ and binaphthylene‐based poly(ester‐imide)s exhibited excellent solubility in common organic solvents such as tetrahydrofuran, m‐cresol, pyridine and dichloromethane. However, binaphthylene‐based poly(ester‐imide)s were more soluble than those of biphenylene‐based polymers in highly polar organic solvents, including N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 261 and 315 °C. Thermal behaviour of the polymers obtained was characterized by thermogravimetric analysis, and the 10 % weight loss temperatures of the poly(ester‐imide)s was in the range 449–491 °C in nitrogen. Furthermore, crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resultant poly(ester‐imide)s exhibited nearly an amorphous nature, except poly(ester‐imide)s derived from hydroquinone and 4,4′‐dihydroxybiphenyl. In general, polymers containing binaphthyl units showed higher thermal stability but lower crystallinity than polymers containing biphenyl units. Copyright © 2005 Society of Chemical Industry     

Simple preparation and characterization of molecularly imprinted nylon 6 nanofibers for the extraction of bisphenol A from wastewater

Nylon 6 nanofibers incorporated with molecularly imprinted polymers (MIPs) were successfully fabricated by electrospinning with fiber diameters in the range 80–145 nm. Then, they were used as a new material for the extraction of selected bisphenol A (BPA) in water samples. Field emission scanning electron microscopy images revealed that the nanofibers had a smooth morphology with a good incorporation of MIPs. The Fourier transform infrared and energy-dispersive X-ray spectroscopy results also confirmed the formation of the MIPs in the nanofibers. Furthermore, Raman spectroscopy showed that the crystalline structure of the pristine nylon 6 nanofiber was a kind of α form, and the incorporation of MIPs led to a γ-form structure in the nanofibers; this proved the interactions between nylon 6 and the MIPs. Adsorption studies also confirmed that the adsorption efficiency of BPA onto the molecularly imprinted polymer nanofibers (MIP-NFs; 83.5%) was much greater than that onto nonimprinted polymer nanofibers (NIP-NFs; 36.8%). Also, the imprinting factor was 3.4; this strongly implied the successful formation of molecularly imprinted cavities on the MIP-NFs with a strong affinity to BPA. The maximum adsorption capacity of the MIP-NFs was 103.8 mg/g. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47112.     

The release rate and antimicrobial activity of calcium-alginate films containing self-microemulsifying Thymus vulgaris essential oil against Escherichia coli and Staphylococcus aureus

The aim of this study was to fabricate antimicrobial calcium-alginate-based films containing the self-microemulsifying thyme essential oil (TEO) formulations using Tween 80 as the surfactant, and acetic (AA) or propionic (PA) acids as the cosurfactants. A Ca-alginate film containing nano-emulsified TEO as well as a neat Ca-alginate film were considered as the controls. The scanning electron microscopy micrographs showed a highly porous texture for SME films, which resulted in an increase in water vapor permeability and water absorption capacity of these films. The SME films released the TEO completely within 155 min and inhibited the growth of S. aureus and E. coli in in vitro antimicrobial tests. The population of S. aureus and E. coli reduced significantly in ground beef covered with SME films. The results of this study showed that self-microemulsifying TEO films could effectively increase the shelf life of ground beef by controlling its microbial population.     

Selective molecularly imprinted polymer nanofiber sorbent for the extraction of bisphenol A in a water sample

Novel molecularly imprinted polymer nanofibers (MIP‐NFs) were prepared for the adsorption of bisphenol A (BPA) in a water sample using the sol–gel process and the electrospinning technique. The effects of a number of synthesis parameters on the adsorption efficiency were investigated. The successful removal of BPA from MIP‐NFs was studied using UV–visible spectroscopy. The prepared MIP‐NFs were characterized by Fourier transform infrared, field emission SEM, TEM and energy dispersive X‐ray analysis. The results showed that the required molar ratio of 3‐aminopropyltriethoxysilane (APTES) to BPA was 15:1, which indicates a good performance in the rebinding test. Likewise, the molar ratio of APTES:acid:water was 1:2:9. The nylon 6 polymer solution, with a concentration of 12 wt%, showed a maximum adsorption capacity for BPA due to a decrease in the nanofiber diameter and an increase in the accessible sites. Furthermore, the maximum adsorption capacity of BPA was achieved at pH 7. Concerning the binding of BPA on MIP‐NFs, the experimental data matched well with the pseudo‐second‐order kinetics data and the Sips isotherm model. The saturated binding capacity for MIP‐NFs was predicted to be 115.1 mg g^?1, which was more than twice as high as that for non‐imprinted polymer nanofibers (46.82 mg g^?1). The results obtained in this study confirmed that the prepared MIP‐NFs showed considerable binding specificity for BPA in comparison with similar structural compounds such as phenol, naphthol and Naphthol AS, in aqueous solution. The binding capacity of MIP‐NFs remained almost constant after five cycles of reuse. The real sample analysis indicated that MIP‐NFs could be utilized as a useful sorbent material for the extraction of BPA from a water sample.     

The Interaction Between SrFeCo0.5O x Ceramic Membranes and Pt/CeZrO2 During Syngas Production from Methane

Non-porous ceramic membranes with mixed ionic and electronic conductivity have received significant interest as membrane reactor systems for the conversion of methane to higher value products. In this work, the role of the membrane in the conversion of methane and the interaction with a Pt/CeZrO₂ catalyst has been studied. Pulse studies of reactants and products over physical mixtures of crushed membrane material and catalyst have clearly demonstrated that a synergy exists between the membrane and the catalyst under reaction conditions. The degree of catalyst/membrane interaction strongly impacts the conversion of methane and the catalyst performance.     

Soluble soybean polysaccharide/TiO2 nanocomposites: Biological activity,release behavior,biodegradability, and biosafety

This study aimed to produce and characterize eco-friendly SSPS nanocomposites incorporated with various concentrations of TiO₂ nanoparticles (NPs) (1%, 3%, and 7%). The antimicrobial activity of the nanocomposite films against five strains of pathogenic bacteria was examined. Salmonella typhi PTCC 1609 was the most sensitive species to TiO₂ NPs at concentrations equal to the synthetic antibiotic. The migration of TiO₂ to ethanol and acetic acid, as two food simulants increased when the initial nano-TiO₂ content increased. The release profiles for TiO₂ in two simulants of ethanol and acetic acid indicated a non-Fickian release, and the release kinetics were concentration-dependent. SSPS/TiO₂ nanocomposites degraded easily and thus have the potential to be applied as an eco-friendly packaging system. Oral administration of doses of 1, 12.5, 25, 50, and 75 mg/kg TiO₂ revealed that the dose of 50 and 75 mg/kg increased malondialdehyde (p < .001) concentration in the liver tissue. In addition, it decreased glutathione (p < .001) concentration in the liver tissue.     

Quality Evaluation of Groundwater Resources using Geostatistical Methods (Case Study: Central Lorestan Plain,Iran)

In this research, based on the qualitative data of 40 wells, variations of water quality parameters of the Central Plain Aquifer were evaluated using kriging and IDW (Inverse Distance Weighting) methods. Owing to the normal distribution of the studied parameters (except Na⁺, SO₄^2?, and TH: total hardness), ordinary kriging was used for modeling. The analysis of the data trends indicated that all the variables were influenced by in two general trends, i.e., NW–SE and NE–SW. In fact, these trends were a result of the effect of the structural conditions on aquifer properties such as transmissivity and flow direction. Variogram analysis (based on C₀ near zero and C₀/σ² ratio between 0.0–0.5) showed that the Na⁺, TDS (total dissolved solids), Ca²⁺, and TH variables have a good spatial structure and the BOD (biochemical oxygen demand), COD (chemical oxygen demand), NO₃^?, and EC variables have poor spatial structure. The BOD, COD, NO₃^?, and EC (electrical conductivity) variables have the smallest range and isotropic distribution. On the other hand, the Ca²⁺, Mg²⁺, Na⁺, SO₄^2?, Cl^?, HCO₃^?, pH, TDS, TH and Alk (alkalinity) parameters are characterized by anisotropic distributions. The Na⁺, TDS, Ca²⁺, and TH variables have the largest range. The results showed that both the IDW and kriging methods have close estimates to one another. The pH variable decreases toward the outlet whereas the EC and TDS variables increase along the direction of water flow and toward the outlet. The distributions of the BOD and COD variables do not perfectly match with the aggregation of industrial activities in the central part as well as the agricultural activities in the southeastern and central parts of the aquifer. The distributions of the Ca²⁺, Mg²⁺, and Alk variables completely follow the geology condition and regional spread of carbonate formations. The Na⁺ concentration increases from the center toward the outlet. The concentration of the Cl^? variable is the highest in the central part of the plain due to the concentration of agricultural and industrial activities. The distribution of the SO₄^2? variable is influenced by a natural factor (lithology), especially in the southeastern parts and the outlet as well as artificial factors (agricultural and industrial activities) in the central and southeastern parts of the aquifer. The NO₃^? variable, which is directly influenced by agricultural and livestock-farming activities, has its maximum concentration in the southeastern areas.     

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.     

Student’s perceptions towards using e-learning via Facebook

Research on utilising social networks for teaching and learning is relatively scarce in the context of information systems. There is far more emphasis on studying the usage of social networks towards fulfilling individuals’ basic social needs. This study uses the unified theory of acceptance and use of technology (UTAUT2) to analyse students’ intention to use and use of e-learning via Facebook. It incorporates playfulness into the UTAUT2 model and categorises the determinants of intention to use e-learning via Facebook into three categories, namely, hedonic values, utilitarian values, and communication values. The data were collected in a two-stage survey from 170 undergraduate students, and the model was tested using structural equation modelling. We found that hedonic motivation, perceived playfulness, and performance expectancy were strong determinants of students’ intention to use e-learning, while habit and facilitating conditions all positively affected students’ use of e-learning via Facebook. The results of this study report new knowledge that academic institutions can utilise to create appropriate e-learning environments for teaching and learning. A number of theoretical and managerial implications for universities’ implementation technologies were also identified.