Fabrication of bimetallic Pt/Pd nanoparticles on 2-thiolbenzimidazole functionalized reduced graphene oxide for methanol oxidation

In this study, an electrocatalyst based on 2-thiolbenzimidazole (TBI) functionalized reduced graphene oxide (rGO) with platinum and palladium nanoparticles (Pt-PdNPs) was synthesized. The successful synthesis of nanomaterials and the prepared glassy carbon electrode (GCE) surfaces were confirmed by transmission electron microscope, X-ray photo electron spectroscopy, scanning electron microscope, electrochemical impedance spectroscopy and X-ray diffraction method. The effective surface areas of TBIrGO/GCE, PdNPs/TBIrGO/GCE, PtNPs/TBIrGO/GCE and Pt-PdNPs/TBIrGO/GCE were calculated to be 324, 578, 667 and 1189 cm²/mg, respectively. According to the results, the electrochemical surface area of the Pt-PdNPs/TBIrGO is 3.67, 2.06 and 1.78 times higher than those of TBIrGO, PdNPs/TBIrGO and PtNPs/TBIrGO, respectively. The Pt-PdNPs/TBIrGO/GCE also exhibited higher peak current for methanol oxidation than those of comparable TBIrGO/GCE, PdNPs/TBIrGO/GCE, PtNPs/TBIrGO/GCE modified GCEs, thus providing evidence for its higher electro-catalytic activity.     

Nano-Impact Single-Entity Electrochemistry Enables Plasmon-Enhanced Electrocatalysis**

Plasmon-enhanced electrocatalysis (PEEC), based on a combination of localized surface plasmon resonance excitation and an electrochemical bias applied to a plasmonic material, can result in improved electrical-to-chemical energy conversion compared to conventional electrocatalysis. Here, we demonstrate the advantages of nano-impact single-entity electrochemistry (SEE) for investigating the intrinsic activity of plasmonic catalysts at the single-particle level using glucose electrooxidation and oxygen reduction on gold nanoparticles as model reactions. We show that in conventional ensemble measurements, plasmonic effects have minimal impact on photocurrents. We suggest that this is due to the continuous equilibration of the Fermi level (E_F) of the deposited gold nanoparticles with the E_F of the working electrode, leading to fast neutralization of hot carriers by the measuring circuit. The photocurrents detected in the ensemble measurements are primarily caused by photo-induced heating of the supporting electrode material. In SEE, the E_F of suspended gold nanoparticles is unaffected by the working electrode potential. As a result, plasmonic effects are the dominant source of photocurrents under SEE experimental conditions.     

Genotypic variability for carbon isotope discrimination in the mutant and improved lines of barley

Drought tolerance is an important breeding objective in dry and semi-dry conditions. Carbon isotope discrimination (Delta) is a tool that may be used to improve water-use efficiency (WUE) as an indirect selection criterion. The study investigated the variability for Delta in improved F7 lines and their parents (three cultivars and two mutant lines), which were sampled randomly from an F6 nursery performing well under semi-dry conditions. In total, 40 entries were grown in sand culture, arranged in three-replicated randomized complete block designs in two sets of experiments in Antalya, Turkey. There were statistically significant differences (p<0.01) among genotypes in both sets of experiments for Delta, and Delta values range from 20.14 to 21.86. Low coefficient of variation (C.V.) values, i.e. 2 and 1.65 %, for both data sets revealed efficient control of experimental error for Delta and indicated little effect of environment. Consequently, broad-sense heritability estimates for Delta were 0.63 and 0.74. As Delta showed a considerably high heritability and consistency over the two sets of experiments and low C.V. values, it was concluded that this trait could be used in breeding programmes aimed at developing drought tolerance lines. The early heading mutant, M-K-88, and the cultivar selected from land race, Tokak 157-37, showed lowest Delta values, indicating that they had the best water-use efficiency. Low Delta values of these two genotypes were inheritable.     

Living anionic surface initiated polymerization (LASIP) of isoprene from silica nano- and glass particles

Living anionic surface initiated polymerization (LASIP) of isoprene from initiator modified silica nano- and glass particles is conducted. In order to prepare polyisoprene-silica composites, the surfaces of the particles are modified with three coupling agents, each bearing a diphenyl ethylene (DPE) moiety with different alkyl-spacer lengths, thus separating the DPE moiety in different distance from the particles’ surfaces. Surface initiated polymerization reactions from modified particle surfaces are performed by using n-BuLi to activate the DPE units and benzene as solvent via LASIP. Grafted polyisoprene-silica composites are analyzed via TGA, resulting in grafting densities of the produced inorganic-polymer composites in the range from 0.10 to 0.24 chains/nm². Analysis via GPC reveals polydispersity values ranging from 1.1 to 1.7. The final microstructure of the grafted polyisoprene is investigated via NMR, revealing 15% 1,2, 35% cis-1,4 and 50% trans-1,4, irrespective of the spacer length of the DPE bearing coupling agent.     

ANP application for evaluating Turkish mobile communication operators

The proposed decision model, based on Analytic Network Process (ANP), has been developed in order to determine the dynamics of the Global System for Mobile Communications (GSM) market. In accordance with the sequence of ANP, first of all, the problem was structured and modeled. At the next step, a quantitative analysis was conducted with the customers in order to assess the importance of the related factors and forecast the market shares of the Turkish mobile communication operators. The forecasted market share values were compared with actual ones for the validation of the decision model. The assessed importance of the factors in a valid model would be a potential competitive advantage for the mobile operators.     

On the stability and properties of the polyacrylate/Na-MMT nanocomposite obtained by seeded emulsion polymerization

For high performance waterborne coatings usually polymer latexes with low emulsifier content are more preferred. Although polymer/clay nanocomposites offer improved properties, it is difficult to produce clay based nanocomposite latexes containing low emulsifier due to the stabilization problems especially caused by organoclays. Present study deals with the preparation of a tBA/BA/MAA ternary copolymer/clay nanocomposite containing 3 wt.% sodium montmorillonite (Na⁺-MMT) via seeded emulsion polymerization. Experimentally it was observed that even the usage of hydrophilic clay caused stabilization problem and a certain amount of emulsifier (>1 wt.%) was necessary to obtain stable latexes. In addition, the usage of a low molecular weight water soluble polymer as steric barrier was found to increase the stability of system. Obtained nanocomposite latex showed fine particle size diameter (127 nm) and very narrow size distribution (PDI = 0.06). The WAXD and TEM investigations indicated that a mostly exfoliated nanocomposite was obtained. Thermal analyses (DSC, DMTA and TGA) showed that there was no change at T_g of the copolymer while very high improvement was obtained for elastic modulus and a slight increase in thermal stability. According to the rheological measurements, the nanocomposite latex showed a higher low shear viscosity, a stronger shear thinning behavior and an improved physical stability in comparison to the reference latex.     

Selective syntheses of vinylenedithiathiophenes (VDTTs) and dithieno[2,3-b;2′,3′-d]thiophenes (DTTs); building blocks for π-conjugated systems

Selective syntheses of 3,4-vinylenedithiathiophenes (VDTTs) and dithieno[2,3-b;2′,3′-d]thiophenes (DTTs), having Ph, 4-CH₃OC₆H₄, 4-BrC₆H₄, 4-NO₂C₆H₄ and 4-(CH₃)₂NC₆H₄ groups, were achieved through the reaction of 1,8-diketone with phosphorus decasulfide (P₄S₁₀). The reaction could be shifted between VDTT and DTT by adding base (sodium bicarbonate) or acid (para-toluenesulfonic acid), respectively, to the reaction mixture. While the VDTTs were obtained in moderate yields, an important achievement has been made with the syntheses of the DTTs, obtaining them in higher yields compared with the previous report. Polymers of the VDTTs, which are the analogues of ethylenedioxythiophene, EDOT, were prepared using FeCl₃. Unfortunately, all attempts for their electropolymerization failed. Spin density calculations revealed that none of the VDTTs had a significant positive spin density at the ‘α’ carbon atoms of the thiophene ring. Considering their solubility and functional groups, which could be further derivatized, they are useful building blocks for the preparation of new organic materials.     

An adaptive large neighborhood search algorithm for a selective and periodic inventory routing problem

We study a selective and periodic inventory routing problem (SPIRP) and develop an Adaptive Large Neighborhood Search (ALNS) algorithm for its solution. The problem concerns a biodiesel production facility collecting used vegetable oil from sources, such as restaurants, catering companies and hotels that produce waste vegetable oil in considerable amounts. The facility reuses the collected waste oil as raw material to produce biodiesel. It has to meet certain raw material requirements either from daily collection, or from its inventory, or by purchasing virgin oil. SPIRP involves decisions about which of the present source nodes to include in the collection program, and which periodic (weekly) routing schedule to repeat over an infinite planning horizon. The objective is to minimize the total collection, inventory and purchasing costs while meeting the raw material requirements and operational constraints. A single-commodity flow-based mixed integer linear programming (MILP) model was proposed for this problem in an earlier study. The model was solved with 25 source nodes on a 7-day cyclic planning horizon. In order to tackle larger instances, we develop an ALNS algorithm that is based on a rich neighborhood structure with 11 distinct moves tailored to this problem. We demonstrate the performance of the ALNS, and compare it with the MILP model on test instances containing up to 100 source nodes.