Electrical and optical properties of diketopyrrolopyrrole-based copolymer interfaces in thin film devices

Two donor-acceptor diketopyrrolopyrrole (DPP)-based copolymers (PDPP-BBT and TDPP-BBT) have been synthesized for their application in organic devices such as metal-insulator semiconductor (MIS) diodes and field-effect transistors (FETs). The semiconductor-dielectric interface was characterized by capacitance-voltage and conductance-voltage methods. These measurements yield an interface trap density of 4.2 × 10(12) eV?1 cm?2 in TDPP-BBT and 3.5 × 1012 eV?1 cm?2 in PDPP-BBT at the flat-band voltage. The FETs based on these spincoated DPP copolymers display p-channel behavior with hole mobilities of the order 10?3 cm2/(Vs). Light scattering studies from PDPP-BBT FETs show almost no change in the Raman spectrum after the devices are allowed to operate at a gate voltage, indicating that the FETs suffer minimal damage due to the metal-polymer contact or the application of an electric field. As a comparison Raman intensity profile from the channel-Au contact layer in pentacene FETs are presented, which show a distinct change before and after biasing.     

Modification of bean starch by γ-irradiation: Effect on functional and morphological properties

Starches isolated from Red, White, Yellow and Black Kidney beans were treated by γ-irradiation doses of 5, 10 and 20 kGy. Physicochemical, morphological and pasting properties of irradiated bean starches were investigated. Microscopic observation under scanning electron microscope (SEM) showed that some of the bean starch granules were destroyed by γ-irradiation and the breakage was greater at a higher dose (20 kGy). Physicochemical properties differed significantly and showed strong dose-dependent relationship. Carboxyl content, solubility, water absorption capacity and transmittance increased, whereas swelling power, apparent amylose content, syneresis and pasting properties decreased upon the irradiation of kidney bean starch. Radiation doses were positively correlated with water absorption capacity and solubility index and negatively correlated with swelling index, peak viscosity, trough viscosity, breakdown and final viscosity. There were high positive correlations between pasting properties. X-ray diffraction pattern remained same upon irradiation but a decrease in crystallinity was observed with increasing irradiation dose.     

System identification of a class of Wiener systems with hysteretic nonlinearities

Existing works on Wiener system identification have essentially been focused on the case where the output nonlinearity is memoryless. When memory nonlinearities have been considered, the focus has been restricted to backlash like nonlinearities. In this paper, we are considering Wiener systems where the output nonlinearity is a general hysteresis operator captured by the well‐known Bouc–Wen model. The Wiener system identification problem is addressed by making use of a steady‐state property, obtained in periodic regime, referred to as ‘hysteretic loop assumption’. The complexity of this problem comes from the system nonlinearity as well as its unknown parameters that enter in a non‐affine way in the model. It is shown that the linear part of the system is accurately identified using a frequency method. Then, the nonlinear hysteretic subsystem is identified, on the basis of a parameterized representation, using a prediction‐error approach. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of Neutron Flux,Frequency and Temperature on the Dielectric Loss of Nano SiO<Subscript>2</Subscript> Particles

In the present work, nano SiO₂ has been irradiated by a 2 × 10¹³ n ?cm^?2s^?1 neutron flux at different times up to 20 h. It has been comparatively analyzed for the frequency dependencies of dielectric loss of the nanomaterial at the initial state and after neutron irradiation. From the analysis results, it is seen that under the influence of neutron flux the dielectric loss of nano SiO₂ decreases with increase of neutron flux. Simultaneously, at all temperatures within f(tgδ) = f(f) dependencies there are peaks of more or less extent. The obtained peaks and the mechanism of other effects are identified.     

Porous dye affinity beads for albumin separation from human plasma

Porous polymeric beads were obtained by the suspension polymerization of 2‐hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA). Poly(HEMA–EGDMA) beads were characterized by surfacearea measurements, swelling studies, FTIR, scanning electron microscopy (SEM), and elemental analysis. Poly (HEMA–EGDMA) beads had a specific surface area of 56 m²/g. SEM observations showed that the poly(HEMA–EGDMA) beads abounded macropores. Poly(HEMA–EGDMA) beads with a swelling ratio of 55%, and containing different amounts of Reactive Red 120 (9.2–39.8 μmol/g) were used in the adsorption/desorption of human serum albumin (HSA) from aqueous solutions and human plasma. The nonspecific adsorption of HSA was very low (0.2 mg/g). The maximum HSA adsorption amount from aqueous solution in phosphate buffer was 60.1 mg/g at pH 5.0. Higher HSA adsorption value was obtained from human plasma (up to 95.7 mg/g) with a purity of 88%. The equilibrium monolayer adsorption amount, Q_max was determined as 172.4 mg/g. The dimensionless separation factor (R_L) value shows that the adsorption behavior of HSA onto the Reactive Red 120 attached poly(HEMA–EGDMA) beads was favorable (0 < R_L < 1). Desorption of HSA from Reactive Red 120 attached poly (HEMA–EGDMA) beads was performed using 0.1M Tris/HCl buffer containing 0.5M NaCl. It was observed that HSA could be repeatedly adsorbed and desorbed with Reactive Red 120‐attached poly(HEMA–EGDMA) beads without significant loss in the adsorption amount. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Metal‐chelating properties of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) membranes

Metal‐chelating membranes have advantages as adsorbents in comparison with conventional beads because they are not compressible and they eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) [poly(HEMA–MAH)] membranes for the removal of three toxic heavy‐metal ions—Cd(II), Pb(II), and Hg(II)—from aquatic systems. The poly(HEMA–MAH) membranes were characterized with scanning electron microscopy and ¹H‐NMR spectroscopy. The adsorption capacity of the poly(HEMA–MAH) membranes for the selected heavy‐metal ions from aqueous media containing different amounts of these ions (30–500 mg/L) and at different pH values (3.0–7.0) was investigated. The adsorption capacity of the membranes increased with time during the first 60 min and then leveled off toward the equilibrium adsorption. The maximum amounts of the heavy‐metal ions adsorbed were 8.2, 31.5, and 23.2 mg/g for Cd(II), Pb(II), and Hg(II), respectively. The competitive adsorption of the metal ions was also studied. When the metal ions competed, the adsorbed amounts were 2.9 mg of Cd(II)/g, 14.8 mg of Pb(II)/g, and 9.4 mg of Hg(II)/g. The poly(HEMA–MAH) membranes could be regenerated via washing with a solution of nitric acid (0.01M). The desorption ratio was as high as 97%. These membranes were suitable for repeated use for more than three adsorption/desorption cycles with negligible loss in the adsorption capacity. The stability constants for the metal‐ion/2‐methacryloylamidohistidine complexes were calculated to be 3.47 × 10⁶, 7.75 × 10⁷, and 2.01 × 10⁷ L/mol for Cd(II), Pb(II), and Hg(II) ions, respectively, with the Ruzic method. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1213–1219, 2005     

Synthesis, Characterization and Biological Studies of Oil Based Tin Polymer

The antimicrobial activity of a newly prepared vegetable oil based organotin polymer by the condensation reaction between fattyamide diol (N, N¹-bis 2 hydroxy ethyl castor oil fatty amide) and butyltin chloride dihydroxide has been studied against the bacterial species E. coli, S. typhi (Gram-negative), S. subtillis, S. aureus (Gram-positive) and three fungal strains (Candida albicans ATCC-10261, Candida glabrata ATCC-90030, Candida tropicalis ATCC-750). The antifouling property of this polymer has also been investigated. The conventional spectroscopic techniques such as FTIR, ¹H-NMR and ¹³C-NMR have been used to establish the structure of the polymer. The physicochemical characteristics like acid value, hydroxyl value, saponification value, iodine value, specific gravity and viscosity were determined by standard laboratory methods. In addition the thermal stability was analysed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The polymer was found fairly active against the tested microbial species and showed antifouling property.     

N‐acetyl‐D‐galactosamine‐specific lectin isolation from soyflour with poly(HPMA‐GMA) beads

Soybean lectin was purified from seeds of Glycine max L.Merrill SA88. Poly(hydroxypropyl methacrylate‐glycidyl methacrylate) [poly(HPMA‐GMA)] beads were used as an affinity matrix and N‐acetyl‐D ‐galactosamine (GalNAc) was used as an affinity ligand. Soybean lectin adsorption with GalNAc attached poly(HPMA‐GMA) beads from soybean lectin solution (in phosphate buffered saline) was 5.0 mg/g. Maximum adsorption capacity for soybean lectin from the soy flour extract was 26.0 mg/g. Elution of soybean lectin from adsorbent was accomplished by 0.5M galactose solution. Purity of soybean lectin was determined by SDS‐PAGE. It was observed that soybean lectin could be repeatedly adsorbed and desorbed with GalNAc‐attached poly(HPMA‐GMA) beads. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009