Synthesis and characterization of conducting copolymer of (<Emphasis Type="Italic">N</Emphasis><Superscript>1</Superscript>,<Emphasis Type="Italic">N</Emphasis><Superscript>3</Superscript>-bis(thiophene-3-ylmethylene)benzene-1,3-diamine-co-3,4-ethylenedioxythiophene)

Electrochemical copolymerization of N ¹,N ³-bis(thiophene-3-ylmethylene)benzene-1,3-diamine (TMBA) with 3,4-ethylenedioxythiophene (EDOT) was carried out in a CH₃CN/LiClO₄ (0.1 M) solvent-electrolyte via potentiodynamic electrolysis. Chemical structure of the monomer was determined by nuclear magnetic resonance (¹H NMR) and Fourier transform infrared (FTIR) spectroscopy. The resulting copolymer was characterized by cyclic voltammetry (CV), FTIR, scanning electron microscopy (SEM), and thermogravimetry analyses (TGA). Conductivity measurements of the copolymer and PEDOT (poly(3,4-ethylenedioxythiophene)) were carried out by the four-probe technique.     

Synthesis and characterization of poly{2-[3-(1H-pyrrol-2-yl)phenyl]-1H-pyrrole} and its copolymer with EDOT

A pyrrole-functionalized monomer 2-[3-(1H-pyrrol-2-yl)phenyl]-1H-pyrrole (PyPhPy) was synthesized. The structure of monomer was investigated by Nuclear Magnetic Resonance (¹H NMR) and Fourier Transform Infrared (FTIR) spectroscopy. The chemical polymerization of PyPhPy (CPyPhPy) was realized using FeCl₃ as the oxidant. The electrochemical oxidative polymerization of polymer P(PyPhPy) and its copolymer with 3,4-ethylenedioxythiophene poly(2-[3-(1H-pyrrol-2-yl)phenyl]-1H-pyrrole-co-3,4-ethylenedioxythiophene) [P(PyPhPy-co-EDOT)] were achieved via potentiodynamic method by using NaClO₄/LiClO₄ as the supporting electrolyte in CH₃CN. Characterizations of the resulting polymers were performed by cyclic voltammetry (CV), FTIR, scanning electron microscopy (SEM), UV-Visible spectrophotometry (UV-Vis) and thermogravimetry analyses (TGA). Electrical conductivity of CPyPhPy, P(PyPhPy), and P(PyPhPyco-EDOT) were measured by four-probe technique.     

High-Density and Thermally Stable Palladium Single-Atom Catalysts for Chemoselective Hydrogenations

Single-atom catalysts (SACs) have shown superior activity and/or selectivity for many energy- and environment-related reactions, but their stability at high site density and under reducing atmosphere remains unresolved. Herein, we elucidate the intrinsic driving force of a Pd single atom with high site density (up to 5 wt %) under reducing atmosphere, and its unique catalytic performance for hydrogenation reactions. In situ experiments and calculations reveal that Pd atoms tend to migrate into the surface vacancy-enriched MoC surface during the carburization process by transferring oxide crystals to carbide crystals, leading to the surface enrichment of atomic Pd instead of formation of particles. The Pd₁/α-MoC catalyst exhibits high activity and excellent selectivity for liquid-phase hydrogenation of substituted nitroaromatics (>99 %) and gas-phase hydrogenation of CO₂ to CO (>98 %). The Pd₁/α-MoC catalyst could endure up to 400 °C without any observable aggregation of single atoms.     

General issues connecting flavor symmetry and supersymmetry

We motivate and construct supersymmetric theories with continuous flavor symmetry, under which the electroweak Higgs doublets transform non-trivially. Flavor symmetry is spontaneously broken at a large mass scale in a sector of gauge-singlet fields; the light Higgs multiplets naturally emerge as special linear combinations that avoid acquiring the generic large mass. Couplings of the light Higgs doublets to light moduli fields from the singlet sector could lead to important effects in the phenomenology of the Higgs sector.     

Connection of silicon nanocrystals (Si-nc) with multi-walled carbon nanotubes

During the last decade silicon nanocrystals (Si-nc) have received widespread interest because of their high quantum efficiency for light emission at room temperature. However, the challenge still ahead is to study and apply these to single Si-ncoptoelectronics, i.e., solving problems linked with connection and manipulation. In this letter we report on connecting (wiring) single Si-nc with conducting multi-walled carbon nanotubes (MWNTs). We have been able to establish a strong mechanical connection by direct growth of MWNTs on Si-nc used as support of iron nanoparticles, by catalytic chemical vapor deposition (CCVD). To monitor the initial stage of the MWNTs growth process, we used a tapered element oscillating microbalance (TEOM). We compared the growth process on Si-nc coated by iron (Fe/Si-nc) to the standard process of growing MWNTs on alumina as support for iron (Fe/Al). The results showed that in the case of Fe/Si-nc catalyst, we obtained three times larger diameter of multi-walled CNTs compared to Fe/Al. This was mainly due to the Si-nc size. The diameter of the CNTs only depended on the size of the Si-nc particles that rested stuck on the tip of the MWNTs. The connected Si-nc kept their photoluminescence properties at room temperature. The present findings open new opportunities in the development of nanodevices for the optoelectronic application field. PACS 81.07.Bc; 81.07.Lk; 81.07.De     

Adsorption of Strontium on Illite

Adsorption of strontium on illite type clay has been studied as a function of shaking time, the ratio of solution volume to weight of clay and the concentration of adsorbate, using ⁹⁰Sr as a tracer. The adsorption experiments were carried out using the batch method and initial Sr²⁺ ion concentrations ranged from 10^–6 to 10^–1 M. The influence of Ca²⁺ and Ba²⁺ cations on Sr adsorption were also studied. These effects are correlated with the ionic radii of alkaline earth ions present in the solution. The Freundlich and Dubinin Radushkevich (D-R) isotherm have been applied to the data and the parameters of the isotherm equations were calculated. The mean energy of adsorption, E was also calculated from the adsorption energy constant, K and maximum capacity X _m values were determined from linearized D-R equation. From empirical Freundlich parameters a site distribution function was calculated.     

Volume transfer constant (K) maps from dynamic contrast enhanced MRI as potential guidance for MR-guided high intensity focused ultrasound treatment of hypervascular uterine fibroids

Higher perfusion of uterine fibroids at baseline is recognized as cause for poor efficacy of MR-guided high intensity focused ultrasound (HIFU) ablation, and higher acoustic power has been suggested for the treatment of high-perfused areas inside uterine fibroids. However, considering the heterogeneously vascular distribution inside the uterine fibroids especially with hyper vascularity, it is not easy to choose the correct therapy acoustic power for every part inside fibroids. In our study, we presented two cases of fibroids with hyper vascularity, to show the differences between them with different outcomes. Selecting higher therapy acoustic powers to ablate high-perfused areas efficiently inside fibroids might help achieving good ablation results. Volume transfer constant (K^trans) maps from dynamic contrast-enhanced (DCE) imaging at baseline helps visualizing perfusion state inside the fibroids and locating areas with higher-perfusion. In addition, with the help of K^trans maps, appropriate therapy acoustic power could be selected by the result of initial test and therapy sonications at different areas with significantly different perfusion state inside fibroids.