Preparation of micro- and nanopatterns of polymer chains grafted onto flexible polymer substrates

In this work a simple novel method for preparing micro- and nanoscale patterns of polymer chains grafted onto flexible polymer substrates is described. A combination of the two techniques of radiation grafting and "grafting-from" has been made. This combination makes it possible to prepare grafted structures having micro- or nanoscale lateral dimensions that are determined by the electron beam or X-ray irradiation patterns used. The height of the grafted features can be controlled by the irradiation dose or such grafting reaction conditions as time, temperature, or monomer concentration. Our first results for nanopatterned samples demonstrate resolution comparable to those of other polymer-based lithography processes.     

Minimizing Side Product Formation in Alkyne Functionalization of Ruthenium Complexes by Introduction of Protecting Groups

The synthesis of alkyne functionalized bipyridine ruthenium complexes are reported. The improved synthetic approach through application of stable protecting groups prevents formation of possible side products while facilitating purification. By applying copper-catalysed azide-alkyne cycloaddition reactions (CuAAC) pyrene units with flexible alkyl linkers are introduced at the periphery of the complex, opening up various applications including surface immobilization and DNA intercalation. All complexes are characterized structurally as well as photophysically, especially regarding the influence of the introduced alkyne and triazolyl substituents on their photophysical behavior.     

Investigation of spectroscopic studies and DFT calculations on glucofuranose derivatives of dithiophosphonates

Abstract

2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson’s reagent: LR) was reacted with 1,2:5,6-di-O-cyclohexylidene-α-D-glucofuranose and 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose in toluene and gave rise to crude dithiophosphonic acids. The crude dithiophosphonic acids were treated with excess triethylamine and the triethylammonium salts of dithiophosphonic acids (1) and (2) were isolated by crystallization method. Compounds 1 and 2 were characterized by elemental analysis, IR, and NMR (¹H-, ¹³C- and ³¹P-) spectroscopies and mass spectrometry. In addition, NMR spectra, the electronic properties (the electronic chemical potential, electronegativity, chemical hardness and the global electrophilicity index) and NBO analysis of compound 2 have been calculated by using the Gaussian 16?W program. The electronic properties were calculated using Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies by density functional method (DFT/B3LYP) at 6-31G(d,p) level. The HOMO and LUMO energies are ?5.9 and ?0.72?eV, respectively. The HOMO–LUMO energy difference is 5.18?eV and this value shows that compound 2 has a high stability and low reactivity.     

Synthesis of Some Polymer‐Metal Complexes and Elucidation of their Structures

In this study, the nine coordination polymers of Fe(III), Co(II) and Ni(II) salts have been synthesized using polyacrylamide (PAA), polt(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA) and their structures were characterized by magnetic and conductivity measurements, ultraviolet‐visible (UV‐VIS), FTIR spectroscopy and thermogravimetric analysis (TGA). The structures of Fe(III) complexes in the all coordination polymers were found as tetrahedral. The structures of PAA‐Co(II) coordination polymer was determined as octahedral geometry whereas PEG‐Co(II) and PVA‐Co(II) complexes showed as tetrahedral structure. PAA‐Ni(II) and PEG‐Ni(II) complexes have octahedral geometry, whereas PVA‐Ni(II) has a square planar structure. Besides, the stress‐strain experiments of PVA‐metal coordination polymers obtained rubber‐like structure were carried out and the value of breaking‐strain of PVA‐Ni(II) complex was found to be about 17% of vulcanized natural rubber. The conductivities of the resulting polymer‐metal complexes were measured by four‐probe technique and were found in the range 10^?5?10^?6 Scm^?1. Thus, it was suggested that they can be used in the field potential application of conducting polymers. TGA results revealed that among the complexes PEG‐Fe(III) and PVA‐Fe(III) complexes have the highest thermally stable.     

Nutritional Analysis of Red-Purple and White-Fleshed Pitaya (Hylocereus) Species

Pitaya is one of the most preferred and produced tropical fruit species recently introduced to the Mediterrranean region in Turkey. Due to its nutritional fruits with high economic value, the popularity of pitaya increases steadily in Turkey as an alternative crop. No detailed nutritional analysis has been undertaken in Turkey so far on fruits of the pitaya species. In this study, we determined and compared some nutritional parameters in fruit flesh of two pitaya (dragon fruit) species (Hylocereus polyrhizus: Siyam and Hylocereus undatus: Vietnam Jaina) grown in the Adana province located in the eastern Mediterranean region in Turkey. The individual sugars, antioxidant activity, total phenolic content, phenolic compounds and volatiles were determined for the first time in Turkey on two pitaya species. The results showed that total phenol content and antioxidant capacity are notably higher in red-fleshed fruits than white-fleshed ones and the predominant phenolic compound in fruits of both species was quercetin. The total sugar content and most of the phenolic compounds in fruits of two pitaya species were similar. A total of 51 volatile compounds were detected by using two Solid Phase Micro Extraction (SPME) fibers, coupled with Gas Chromatography Mass Spectrometry (GC-MS) techniques, and more volatile compounds were presented in the white-fleshed species. Total phenolic content (TPC) of the red-fleshed and white-fleshed pitaya species were 16.66 and 17.11 mg GAE/100 g FW (fresh weight). This study provides a first look at the biochemical comparison of red-fleshed and white-fleshed pitaya species introduced and cultivated in Turkey. The results also showed, for the first time, the biochemical content and the potential health benefit of Hylocereus grown in different agroecological conditions, providing important information for pitaya researchers and application perspective.     

Synthesis,characterization, and application of silver nanoparticle‐thiophenol nanocomposite film on the glassy carbon surface

In this study, 4‐thiophenol modified glassy carbon electrode was prepared by the reduction of 4‐diazothiophenol tetrafluoroborate salt. Silver nanoparticles were attached to the thiophenol modified surface to prepare a thiophenol‐silver nanoparticle composite film. 4‐Aminothiopenol molecules were deposited by self‐assembling technique to form multi‐layered nanofilms of TP/SNP/PhNH₂ on glassy carbon substrate. These surfaces were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, X‐ray photoelectron spectroscopy, reflectance‐absorption infrared spectroscopy, and ellipsometry at each multilayer film growth process. Atomic force microscopic images of GC/TP/SNP/PhNH₂ surfaces were also acquired. The characterization methods show that the amine group containing surface permits the subsequent modification by a variety of coupling reactions for the immobilization of more complex systems. An application of the electrode modification for the determination of uric acid with a significantly lower detection limit is described. Copyright © 2013 John Wiley & Sons, Ltd.     

Structural and Optical Properties of Zinc Nitride Films Prepared by Pulsed Filtered Cathodic Vacuum Arc Deposition

Polycrystalline zinc nitride films are deposited on Coming 7059 glass substrates by pulsed filtered cathodic vacuum arc deposition （PFCVAD）. The crystallographic structure is studied by means of x-ray diffraction. These measurements show that all the films are crystallized in the cubic structure, in a preferred orientation along the （332） and （631） directions. Weak XRD signal shows small crystallites distributed in an amorphous tissue. A small improvement of crystallinity is observed with annealing. Optical parameters such as absorption, energy band gap, Urbach tail, extinction coefficients have been determined. The Urbach tail energy is decreased with annealing at 500℃ for one hour. Energy band gap values are found to be increased by annealing.     

Stochastic models for strategic resource allocation in nonprofit foreclosed housing acquisitions

Increased rates of mortgage foreclosures in the U.S. have had devastating social and economic impacts during and after the 2008 financial crisis. As part of the response to this problem, nonprofit organizations such as community development corporations (CDCs) have been trying to mitigate the negative impacts of mortgage foreclosures by acquiring and redeveloping foreclosed properties. We consider the strategic resource allocation decisions for these organizations which involve budget allocations to different neighborhoods under cost and return uncertainty. Based on interactions with a CDC, we develop stochastic integer programming based frameworks for this decision problem, and assess the practical value of the models by using real-world data. Both policy-related and computational analyses are performed, and several insights such as the trade-offs between different objectives, and the efficiency of different solution approaches are presented.