Pyrrole/N‐p‐toluenepyrrole copolymers in the presence of surfactants: A promising material for glucose sensing

In this study, pyrrole/N‐para‐toluenpyrrole (Py/NptPy) copolymers were synthesized by chemical oxidative polymerization method. The effects of different kinds of (anionic, cationic, and nonionic) surfactants on the properties of copolymer were investigated. The structural, morphological, thermal, and conductivity properties of the copolymers were investigated by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and the four‐probe measurement device respectively. FTIR spectra of copolymers synthesized in different environments that support the formation of copolymer. SEM results show that the morphologies of copolymers synthesized in the presence of surfactant are more homogeneous and the particle sizes are smaller than that of polypyrrole (PPy). TGA results revealed that the thermal stabilities of Py/NptPy‐NaDBS (400°C) and Py/NptPy‐Tween 20 (260°C) copolymers were higher than surfactant free Py/NptPy copolymer (180°C) according to their initial decomposition temperatures. It was determined that the conductivity values of copolymers were higher than PNptPy. Glucose sensor properties of copolymer synthesized in the presence of tetradecylthreemethyl ammonium bromide (TTAB) were investigated with cyclic voltammetry (CV) method. Michaelis–Menten constant of Py/NptPy‐TTAB copolymer modified electrochemical biosensor was calculated as 5.30 mM. POLYM. ENG. SCI. 56:995–1003, 2016. © 2016 Society of Plastics Engineers     

One-step synthesis of hybrid magnetic material based on polyphenoxazine and bimetallic Co–Fe nanoparticles

Polymer Bulletin - A simple method for preparation of hybrid magnetic nanocomposites consisting of bimetallic Co–Fe nanoparticles and polyphenoxazine (PPOA) is described. The nanocomposites...     

A new causal discovery heuristic

Probabilistic methods for causal discovery are based on the detection of patterns of correlation between variables. They are based on statistical theory and have revolutionised the study of causality. However, when correlation itself is unreliable, so are probabilistic methods: unusual data can lead to spurious causal links, while nonmonotonic functional relationships between variables can prevent the detection of causal links. We describe a new heuristic method for inferring causality between two continuous variables, based on randomness and unimodality tests and making few assumptions about the data. We evaluate the method against probabilistic and additive noise algorithms on real and artificial datasets, and show that it performs competitively.     

Pervaporation membrane reactor study for the esterification of acetic acid and isobutanol using polydimethylsiloxane membrane

In this study, isobutyl acetate, a valuable solvent in cosmetics, aroma and paint industries, is produced by pervaporation–esterification equilibrium reaction in a batch pervaporation membrane reactor (PVMR) using homogeneous (sulphuric acid) and heterogeneous (Dowex 50W-X8) catalysts. The effects of catalyst loading, catalyst type, reaction time, membrane thickness, temperature and initial molar ratio of reactants were investigated. A cross-linked polydimethylsiloxane (PDMS) membrane selective to esters was prepared and used in PVMR. Batch reactions were carried out also in a simple batch reactor (SBR) without pervaporation under the same conditions to compare the conversions for the reactions with and without pervaporation. In conclusion, PVMR experiments showed that the PDMS membrane can be used to remove the isobutyl acetate formed selectively with acceptable conversions and pervaporation fluxes.     

Energy inputs and crop yield relationships in greenhouse winter crop tomato production

In this study, energy use patterns and the relationship between energy inputs and yield for single crop (winter) greenhouse tomato production were examined in Antalya province, one of the most important greenhouse centres in Turkey. Data were collected using face-to-face surveys from 85 farms producing winter greenhouse tomatoes. The results indicated that the bulk of energy was consumed in fertilizer (38.22%), electricity (27.09%), manure (17.33%) and diesel-oil (13.65%). Average yield and energy consumption were calculated as 57,905.1 kg/ha and 61,434.5 MJ/ha, respectively. Results also determined an output–input ratio of 0.8 and a respective energy productivity and specific energy of 1.061 MJ/t and 0.94 kg/MJ. In addition, the Cobb Douglas production function was applied to test the relationship among different forms of energy consumption. The findings suggested that single crop tomato producers must optimize their use of indirect energy resources. Single crop producers applied an excess use of chemicals, resulting in an inverse effect on yield as well as imposing risks to natural resources and human health. This research suggested an expansion in energy use training opportunities to greenhouse farmers in the region.     

Economic analysis of hydrogen production through a bio-ethanol steam reforming process: Sensitivity analyses and cost estimations

In this study, the hydrogen selling price from ethanol steam reforming has been estimated for two different production scenarios in the United States, i.e. central production (150,000 kg H₂/day) and distributed (forecourt) production (1500 kg H₂/day), based on a process flowchart generated by Aspen Plus^® including downstream purification steps and economic analysis model template published by the U.S Department of Energy (DOE) [1]. The effect of several processing parameters as well as catalyst properties on the hydrogen selling price has been evaluated. $2.69/kg is estimated as the selling price for a central production process of 150,000 kg H₂/day and $4.27/kg for a distributed hydrogen production process at a scale of 1500 kg H₂/day. Among the parameters investigated through sensitivity analyses, ethanol feedstock cost, catalyst cost, and catalytic performance are found to play a significant role on determining the final hydrogen selling price.     

Three-dimensional alumina nanotemplate

Cylindrically and pentagonally shaped three-dimensional (3-D) alumina nanotemplates were fabricated by electrochemical anodization of high purity aluminum. Crack-free 3-D nanotemplates were achieved by anodizing various aluminum pre-formed structures through their concave surfaces. A critical parameter for obtaining crack-free 3-D nanotemplates was manipulating the stress at the aluminum/aluminum-oxide interface, because tensile stress at this interface can cause radial cracks. Two different cathode configurations were used to produce 3-D nanotemplates: inner and outer cathode configuration. The outer cathode configuration allowed fabrication of 3-D alumina templates with smaller diameters (<500 μm) and the inner cathode configuration allowed fabrication of 3-D alumina templates with larger diameters (>500 μm). A larger pore density was observed at the inner surface of 3-D template than at the outer surface due to the curvature of the template. The pore diameter of alumina nanotemplate was strongly depended on the applied current density. No defect was observed independent of anodizing solutions and applied current density. This cost-effective and manufacturable method can be utilized for preparation of hierarchical nanostructures.     

Ni-625 Superalloy Foam Processed by Powder Space-Holder Technique

In this work, porous Ni-625 superalloys were produced by use of a water soluble pore forming agent prior to sintering. Carbamide particles were used as the space-holder materials. After mixing and compaction, the space-holder particles were extracted using warm water leaching over a range of temperatures. The porous green parts were subsequently thermally debinding to remove the paraffin wax under a pure Argon atmosphere, and subsequently sintered at high vacuum. The effects of volume fraction of space-holder particles on density, porosity, and elastic modulus were investigated. Microstructures were captured using optical and scanning electron microscopy. Pore size was quantified using image analysis software integral to the scanning electron microscopy. In addition, compression tests were conducted on the sintered samples.     

Non‐Invasive High‐Throughput Metrology of Functionalized Graphene Sheets

The utilization of fluorescence quenching microscopy (FQM) for quick visualization of chemical functionalization in relatively large regions of graphene, grown via chemical vapor deposition (CVD), is discussed. Through reactive ion plasma etching, patterns of p‐type CVD‐grown graphene functionalized with fluorine are generated. 4‐(dicyanomethylene)‐2‐methyl‐6‐(4‐dimethylaminostyryl)‐4H‐pyran (DCM) is used as the fluorescent agent. The emission of DCM is quenched to a different extent by fluorinated and pristine graphene, which provides the fluorescence‐imaging contrast essential for this metrology. To probe the functionalized surface patterns with DCM, the dye is dispersed in polymethylmethacrylate (PMMA) then the graphene surface is coated, forming a 30‐nm‐thick DCM‐PMMA layer. Fluorescence images of dye‐coated graphene distinctly reveal the difference between the chemically treated and as‐grown regions. The pristine graphene quenches the DCM emission more efficiently than the fluorinated graphene. Therefore, the regions with pristine graphene appear darker on the fluorescence images than the regions with fluorinated graphene, enabling large‐scale mapping of the functionalized regions in CVD grown graphene sheets Due to its simplicity and consistent results, FQM is now poised for widespread adoption by graphene manufacturers as a basis for facile and high throughput metrology of large‐scale graphene sheets.