Novel phthalocyanines containing substituted salicyclic hydrazone-1,3-thiazole moieties: Microwave-assisted synthesis, spectroscopic characterization, X-ray structure and thermal characterization

Novel, metal-free and metallo(Cu, Co, Ni, Zn, Pb and Mn)phthalocyanine compounds were synthesized by exposure to microwave irradiation and the products purified. The newly prepared compounds were characterized using elemental analyses, IR, ¹H/¹³C NMR, ¹H–¹H COSY measurements, MS, UV–vis spectroscopy and DTA/TG analysis. The electronic spectra exhibited an intense π → π* transition with characteristic Q and B bands of the phthalocyanine core, as expected. All decomposition products obtained from DTA/TG analysis were identified; it was found that the thermal stability of each phthalocyanine compound followed the order: MnPc < Metal-free < ZnPc < PbPc < CuPc < CoPc < NiPc.     

Effect of industrial juice concentrate processing on phenolic profile and antioxidant capacity of black carrots

Black carrot concentrate has gained increasing interest in recent years as a natural colourant due to its substantial content of bioactive compounds, especially anthocyanins. Black carrot concentrate production includes several steps, some of which are milling, mashing, pressing, pasteurisation and concentration. In this study, every step of black carrot concentrate processing was investigated to elucidate both the quantitative and qualitative changes in antioxidative compounds using spectrophotometric, HPLC‐based and LC‐QTOF‐MS‐based analyses. The results obtained indicated that processing the raw black carrot material into its concentrate led to an overall reduction of 70%, 73% and 44% in total phenolic, total flavonoid and total monomeric anthocyanin contents on a dry weight basis, respectively. Moreover, concentrate processing resulted in 67% and 71% decreases in total antioxidant capacity, determined using DPPH and CUPRAC methods, respectively, on dry weight basis. Untargeted LC‐MS‐based metabolomics analysis enabled the identification of ten phenolic components including seven anthocyanins and three phenolic acids. HPLC‐based quantification of individual anthocyanins revealed cyanidin‐3‐xylosyl (feruloylglucosyl)galactoside as the major anthocyanin component.     

Effect of absorbed water on oxygen transport in EVOH matrices. A molecular dynamics study

We performed molecular dynamics simulations on oxygen transport in dry and hydrated (with 3 and 13 wt% water content) amorphous ethylene-vinyl alcohol (EVOH) copolymers. As the water content increases, the intermolecular hydrogen bonding in the matrix decreases and the cavity sizes increase, which result in increased diffusion coefficients. The local chain mobility increases significantly only at 13% water content. The predicted glass transition temperatures fall into reported experimental ranges. The solubility coefficients of oxygen slightly decrease with increasing water content, which indicates that the excessive increase in permeability mainly results from increased diffusion rates.     

Molecular simulations of small gas diffusion and solubility in copolymers of styrene

The objective of this study is to investigate the relationship between gas permeability and the chemical structure and conformational properties for copolymers of styrene and its homopolymer. The diffusion and the solubility coefficients of small gas molecules (He, H₂, Ne, O₂, N₂, CH₄, Ar, CO₂) in amorphous structures of poly (styrene-alt-maleic anhydride) copolymer (SMA), poly (styrene-stat-butadiene) rubber (SBR), and atactic polystyrene (PS) are investigated by the transition state approach. Simulation results are found to be in good agreement with the experimentally measured values. The transport behavior of H₂O molecules is also studied in the same bulk structures by fully atomistic molecular dynamics simulations. In general, the diffusion coefficients of the gases in these matrices decrease in the following order: SBR>PS>SMA, whereas the solubility coefficients follow the reverse order. The differences in the mobility of the matrices seem to be the dominant determining factor for diffusion. And the solubility coefficients depend on the free volume distribution of the matrices.     

Ureteral fibroepithelial polyps in children

Fibroepithelial polyps of the ureter presenting as pelviureteric junction (PUJ) obstruction in two boys are reported. These neoplasms are uncommon, especially in children. Surgical excision of the PUJ with the polyp and dismembered pyeloplasty was performed in each case. Postoperative recoveries were uneventful.     

Morphological and impedance studies on electropolymerized 3,4-(2,2-dibenzylpropylenedioxy)thiophene nanostructures on micron sized single carbon fiber

Micron sized single carbon fibers were cyclovoltammetrically coated with poly[3,4-(2,2-dibenzylpropylenedioxy)thiophene] resulting in a nanofiber network at the surface. The method provides conjugated polymer nanostructures covalently and uniformly bound to micron sized substrates. When the electropolymerization is carried out with different electrolytes in acetonitrile the dopant influences the structure of the coating layer what is proved by electrochemical impedance spectroscopy and electron microscopy. Electrodes based on poly[3,4-(2,2-dibenzylpropylenedioxy)thiophene] on single carbon fiber microelectrodes (SCFMEs) prepared in Bu₄NPF₆/ACN show the best capacitance performance due to their higher surface area. The improvement is attributed to the formed nanofiber network structure which results in a more efficient charge transport and collection.     

A hierarchical solution approach for a multicommodity distribution problem under a special cost structure

Motivated by the spare parts distribution system of a major automotive manufacturer in Turkey, we consider a multicommodity distribution problem from a central depot to a number of geographically dispersed demand points. The distribution of the items is carried out by a set of identical vehicles. The demand of each demand point can be satisfied by several vehicles and a single vehicle is allowed to serve multiple demand points. For a given vehicle, the cost structure is dictated by the farthest demand point from the depot among all demand points served by that vehicle. The objective is to satisfy the demand of each demand point with the minimum total distribution cost. We present a novel integer linear programming formulation of the problem as a variant of the network design problem. The resulting optimization problem becomes computationally infeasible for real-life problems due to the large number of integer variables. In an attempt to circumvent this disadvantage of using the direct formulation especially for larger problems, we propose a Hierarchical Approach that is aimed at solving the problem in two stages using partial demand aggregation followed by a disaggregation scheme. We study the properties of the solution returned by the Hierarchical Approach. We perform computational studies on a data set adapted from a major automotive manufacturer in Turkey. Our results reveal that the Hierarchical Approach significantly outperforms the direct formulation approach in terms of both the running time and the quality of the resulting solution especially on large instances.     

A dynamic model of controlling invasive species

A dynamic model of controlling invasive weeds is first developed which is a large scale, nonlinear 0-1 integer programming problem. This model is then applied for the case of control of the invasive grass, Pennisetum ciliare (buffelgrass), in the Arizona desert. The large size of the problem makes the application of direct optimization methods impossible, instead the most frequently suggested strategies were analyzed and their consequences compared. The model is more advanced and complex than those examined in earlier studies.     

Molecular simulations of gas transport in nitrile rubber and styrene butadiene rubber

Nitrile rubber (NBR, 39:61 wt% of acrylonitrile:butadiene) and styrene butadiene rubber (SBR, 50:50 wt% of styrene:butadiene) matrices have been equilibrated by molecular dynamics (MD) simulations. Transition-state approach is used to calculate the diffusion and solubility coefficients of small penetrants in these matrices, indicating quite low values in NBR and reasonable agreement with experimental results. MD simulations have been performed to analyze water diffusion in these matrices. Aggregation of water molecules is observed in the hydrophobic matrix SBR. MD simulations with fictitious nonpolar water molecules inhibit aggregation and lead to enhanced diffusion in SBR. In NBR there is a slight increase in diffusion for fictitious water molecules. The lower diffusion constants in NBR result from slower local relaxation of the matrix due to tighter intermolecular packing and higher cohesive energy density. The free volume distribution that affects solubility coefficients is not a major determining factor for the diffusion coefficients in these matrices.