Acylation of 5-amino-3H-1,3,4-thiadiazolin-2-one

Acylation of 5-amino-3H-1,3,4-thiadiazolin-2-one (2) was undertaken selectively at either the 3-NH position or at 5-amino group depending on reaction conditions. The 3-NH is highly acidic and acylation takes place with acid anhydrides at this position in high yields in the presence of pyridine or triethylamine. The diacylation of both the 3-position and the 5-amino group was only possible via the 5-amino-3-acyl-1,3,4-thiadiazolin-2-one intermediates 4 . Under neutral conditions, acylation only occurs at the 5-amino group with acyl chlorides forming 5-acylamino-3H-1,3,4-thiadiazolin-2-ones 5 . 5-Acetylamino-3H-1,3,4-thiadiazolin-2-one can also be synthesized by the thermal transformation of 5-amino-3-acetyl-1,3,4-thiadi-azolin-2-one in acetic acid.     

Bulk heterojunction polymer solar cells based on binary and ternary blend systems

Polymer solar cells (PSCs) were fabricated using a ternary blend film consisting two conjugated polymers and a soluble fullerene derivative as the donor and acceptor materials, respectively. And, to compare ternary blend system, the single‐component copolymers consisting of the repeating units of each of the copolymers, used in ternary blend solar cells, were designed and synthesized for use as the electron donor materials in binary blend solar cells. We systematically investigated the field‐effect carrier mobilities and the optical, electrochemical, and photovoltaic properties of the copolymers. Under optimized conditions, the binary blend polymer systems showed power conversion efficiencies (PCEs) for the PSCs in the range 3.87–4.16% under AM 1.5 illumination (100 mW cm^?2). All polymers exhibited similar PCEs that did not depend on the ratio of repeating units. The binary blend solar cell containing a single‐component copolymer as the electron donor material performed better than the ternary blend solar cell in this work. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Electric detection of target DNA by fabricating gold nanowire bridges on planar nanogap electrodes

For the electrical detection of target DNA (partial avian influenza virus/H1N1/HA sequence) prepared via asymmetric PCR, we fabricated DNA-templated conducting gold nanowire bridges on planar nanogap electrodes using positively charged gold nanoparticles.     

Recent advances in two-photon imaging: technology developments and biomedical applications

In the past two decades, two-photon microscopy (TPM) transforms biomedicalresearch, allowing nondestructive high-resolution fluorescent molecular imaging and label-free imaging in vivo and in real time. Here we review the recent advances of TPM technologyincluding novel laser sources, new image acquisition paradiams, and microendoscopicimaging systems. Then, we survey the capabilities of TPM imagingof biological relevant molecules such as nicotinamideadenine dinucleotide (NADH), flavin adenine dinucleotide (FAD),and reactive oxygen species (ROS). Biomedical applications of TPM in neuroscience and cancer detection are demonstrated.     

Electro-Flocculation Mechanism of Physical Water Treatment for the Mitigation of Mineral Fouling in Heat Exchangers

Abstract

The objective of the present study was to investigate the mechanism of a physical water treatment (PWT) technology used to mitigate mineral fouling in a heat exchanger. The PWT method tested utilized a solenoid coil to produce induced electric fields in a feed pipe prior to the heat exchanger. Fouling experiments were conducted using well water circulated through a laboratory cooling tower over 270 h with no blowdown, and fouling resistances were determined over time. Compared with the fouling resistance for the baseline case, those obtained with the PWT technology showed high efficacy for maintaining a low fouling resistance value. Samples of circulating well water were collected and analyzed using a laser particle counter over time. After 4 days of operation, the total number of particles was approximately 1 million per cc for the untreated case, whereas the case with PWT produced 3.5 million per cc. The present data on the particle counting provide empirical support for the bulk-precipitation hypothesis for the mechanism of PWT generally and electro-flocculation mechanism for solenoid coil techniques in particular.     

Amination of the Baylis–Hillman Acetates in Ethanol

Baylis–Hillman acetates in EtOH were substituted by various nitrogen nucleophiles to give the corresponding trisubstituted alkenes in high yields.     

Kinetic Study of the Polymerization of Alkyl Vinyl Ethers by HI/12 Catalyst

The polymerization of alkyl vinyl ethers initiated by hydrogen iodide and iodine catalyst has been studied in detail. The polymerization showed living behavior in nonpolar solvents at low (-15°) temperatures as reported earlier by others. The observed rate of polymerization under the reaction conditions was linearly dependent on the initial concentration of hydrogen iodide and iodine, respectively. However, the monomer concentration did not influence the rate of polymerization (apparent zero order). From the observed rate equation, two possible reaction schemes were proposed and attempts were made to distinguish them by using UV/visible spectroscopy and ¹³ C-NMR spectroscopy. In both schemes a reversible interaction between monomer and an iodine molecule was postulated as a necessary elemental reaction to fit the observed expression for rate of polymerization. From the spectroscopic analysis results, the interaction between the iodide compound (chain end) and the iodine molecule seems to be very weak compared to the interaction between monomer and the iodine molecule.     

Quantification of Nb and Zr in the irradiated pressure tubes from Wolsong CANDU Unit 1 by neutron activation analysis

When the Wolsong 1st CANDU reactor in Korea is reaching the end of its original lifespan, decommissioning has been one of the largest issues faced by the nuclear industry and the government for the estimation of expense. The radioactive sources in the construction stuffs and components of the reactor such as pressure tubes, steam generators must be evaluated for the estimation of the appropriate expense for the decommissioning. Unfortunately we do not have exact information about the initial composition of the pressure tubes. In this study the elemental contents of Nb and Zr in the activated zircaloy pressure tubes was investigated. Nb is one of the important elements that characterize the physical and mechanical properties of the pressure tube and a major source of high radioactivity. The prepared samples were strongly irradiated again in the vertical irradiation channel at the HANARO research reactor in the Korea Atomic Energy Research Institute (KAERI) and then measured by an HPGe detector.