Postfunctionalization of aromatic polyamine by [2+2] cycloaddition of 7,7,8,8-tetracyanoquinodimethane with side chain alkynes

Electron-rich, side chain alkynes of an aromatic polyamine were functionalized by a [2+2] cycloaddition, followed by retro-cyclization with the electron-accepting 7,7,8,8-tetracyanoquinodimethane (TCNQ). ¹H NMR studies were used to optimize the reaction conditions. Mild heating to >50?°C afforded the postfunctionalized aromatic polyamines with the desired acceptor amounts. The quantitative TCNQ addition was demonstrated by the MALDI-TOF mass spectrum and elemental analysis. Introduction of the cyano-based acceptor moieties into the polymer side chains resulted in unusually strong intermolecular interactions. In addition to the ?ШC?? interactions of the extended acceptor moieties, these intermolecular forces were supposed to improve the thermal stability of the aromatic polymers. Furthermore, the donor?Cacceptor chromophores formed by this postfunctionalization displayed low energy charge-transfer bands and redox activities in both the anodic and cathodic directions. The straightforward postfunctionalization technique using the alkyne?CTCNQ addition is useful for the preparation of narrow band gap polymers in one step.     

Synthesis and gas sensing properties of SnO<Subscript>2</Subscript> nanoparticles with different morphologies

The SnO₂ particles with different morphologies of nanorod, nanosheet, nanoparticle and nanodot were synthesized by liquid-phase methods. In addition, Pt was loaded on each prepared SnO₂ by dispersing SnO₂ particles into PtCl₄ ^2? aqueous solutions containing 0.67 vol% methanol, followed by UV light irradiation for 6 h. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller measurement. The gas sensing properties of the synthesized SnO₂ were tested by detecting the change in electric resistivity in flowing aceton and methanol gases with nitrogen base. The gas sensing properties greatly changed depending on not only the specific surface area, but also the exposed crystal plane, i.e., the SnO₂ nanorods exposing (111) planes showed the excellent sensitivity and quick response ability, indicating the excellent gas sensing ability of the (111) plane. Furthermore, the Pt loading exceedingly enhanced the gas sensing properties.     

Small-diameter vascular grafts of Bombyx mori silk fibroin prepared by a combination of electrospinning and sponge coating

The present study aimed to produce small-diameter grafts made of a silk fibroin by electrospinning. In order to reinforce the electrospun silk fibroin graft (ES), the graft was coated with a silk sponge (ESSC). Physical properties such as a diameter of the electrospun silk fibers were influenced by a concentration of fibroin solution. Ultimate tensile strength (UTS) of the ESSC graft was improved compared to the ES graft. However, the ESSC graft was less compliant than the ES graft. Importantly, water permeability of the ESSC graft was within the range of which endothelialization was promoted in previous studies.     

Enhanced CaMKII activity and spatial cognitive function in SAMP6 mice.

Senescence-accelerated mouse prone 6 (SAMP6) mice exhibit increased expression of NMDA receptor NR2B subunit (NR2B) and improved short-term memory compared with senescence-accelerated mouse resistance 1 (SAMR1) mice. The Thr286 phosphorylation of alpha calcium/calmodulin-dependent protein kinase II (CaMKII) has a crucial role in plasticity and learning among multiple downstream signaling pathways linked to the NMDA receptor. To examine the relationship between CaMKII activity and spatial learning in SAMP6, the authors employed western blot analysis and behavioral analyses (object location and delayed spatial win-shift eight-arm radial-maze tests). The levels of Thr286 and Ser831 phosphorylation of CaMKII and AMPA receptor subunit glutamate receptor 1 (CaMKII substrate), respectively, were increased in hippocampus of SAMP6 compared with SAMR1. SAMP6 showed faster hippocampal-dependent spatial memory formation than SAMR1 in both the object location and win-shift eight-arm radial-maze tests. Our results indicate that increased CaMKII activity influences the NR2B/CaMKII signal pathway and cognitive function in SAMP6. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development and single laboratory validation for thermoluminescence detection of irradiated foods using X-ray irradiation

The thermoluminescence (TL) method using X-rays was investigated for the purpose of detection of irradiated food, and the method was validated at a single laboratory level. A small X-ray irradiator was developed as an alternative radiation source for normalization, and X-ray irradiation conditions equivalent to gamma-ray irradiation from (60)Co were established. Gamma-ray irradiated spices were used for the method validation. The detection limits (MDL) and lower limit of integrated TL intensities (MDL×10) for the spices were checked and the separation of silicate minerals from the spices was confirmed to be sufficient for TL analysis. There was no significant difference in TL glow ratio obtained using two sets of X-ray irradiation equipment including the newly developed equipment. Repeatability and intermediate precision showed no influence of analysts, X-ray irradiation equipments, or measurement days on the TL ratios. From these results, this detection method was validated in a single laboratory.     

Obtaining hydrocarbons from ethanol over iron-modified ZSM-5 zeolites

The search for new energy sources has impulsed hydrocarbon production from methanol and ethanol over ZSM-5 zeolites. Iron incorporation by different methods has led to a variety of chemical applications. Thus, hydrocarbon production from ethanol was studied over a ZSM-5 zeolite modified by ion exchange and impregnation with iron. XRD, FTIR, TPR, nitrogen adsorption, Mössbauer and photoacoustic spectroscopies were used for the samples characterization. The highest yield of liquid hydrocarbons was obtained with the low iron-exchanged zeolite, especially co-feeding hydrogen. The calcination procedure led to a migration of the iron species, probably forming iron oxide particles.     

Multicolor emission and thin film transistor properties of 1,8-diethynylcarbazole-based conjugated copolymers

1,8-Carbazole-based conjugated copolymers are synthesized by the Sonogashira polycondensation between the 1,8-diethynylcarbazole derivative and dibromo comonomers. The resulting polymers are fully characterized by GPC, and ¹H NMR and IR spectroscopies, and their high thermal stability with the 5% decomposition temperature exceeding 350 °C by thermogravimetric analyses. The optical properties of the carbazole polymers reveal that the comonomer structures significantly affect the absorption and emission spectra. For example, a bathochromic shift of the spectra is achieved when electron-accepting comonomers are selected, finally leading to the production of additive primaries. The mixtures of three carbazole polymers with red, green, and blue emission colors provide a white light emission both in solutions and in thin solid films. In addition, the thin film transistor properties of the carbazole polymers are investigated. The 1,8-carbazole-based polymers display an intermediate mobility between the 2,7-carbazole and 3,6-carbazole-based counter polymers. All these results suggest the potential application possibilities of the 1,8-carbazole-based conjugated polymers in optoelectronic devices.