Detailed Optimization of Polycondensation Reaction via Direct C–H Arylation of Ethylenedioxythiophene

The polycondensation reaction of 3,4‐ethylenedioxythiophene with 2,7‐dibromo‐9,9‐dioctylfluorene via Pd‐catalyzed direct arylation gives poly[(3,4‐ethylenedioxythiophene‐2,5‐diyl)‐(9,9‐dioctylfluorene‐2,7‐diyl)]. The reaction conditions are optimized in terms of the Pd precatalysts, reaction time, and carboxylic acid additives. The combination of 1 mol% Pd(OAc)₂ and 1‐adamantanecarboxylic acid as an additive is the optimized catalytic system, and it yields the corresponding polymer with a molecular weight of 39 400 in 89% yield. The polycondensation reaction, followed by an end‐capping reaction, effectively provides a linear polymer without Br terminals.     

Study of Neutron-Rich Hypernuclei by the (π −, K +) Reaction at J-PARC

We are planning to perform an experiment at J-PARC and produce new neutron-rich Λ hypernuclei by using the (π ^?, K ⁺) reaction (J-PARC E10). As the first step, we are planning to produce ${^6_{\Lambda}{\rm H}}$ hypernuclei with a ⁶Li target. To conduct this experiment, we are developing new detectors, those are scintillating fiber tracker, and silicon strip detector, for high rate operation to aim at increasing beam intensity up to 10⁷/spill. As a result of beam test in Jun 2012, we are going to use high-rate beam at least 10⁷/spill.     

Search for Θ + via the Pion Induced Reaction at J-PARC: J-PARC E19

The Θ ⁺ pentaquark baryon was searched for via the π ^? p → K ^? X reaction at J-PARC. π ^? meson beams were irradiated on the liquid hydrogen target with the beam momentum of 1.92 GeV/c. In the missing mass spectrum, no peak structure corresponding to Θ ⁺ mass was observed. The preliminary upper limit of the differential cross section averaged over the scattering angle of 2° to 15° at the laboratory frame was less than 0.3 μb/sr at the 90 % confidence level in the missing mass region over 1.51 to 1.55 GeV/c ².     

Voltammetric investigation of avidin-biotin complex formation using an electroactive bisbiotinyl compound

Formation of avidin-biotin complex was investigated using bisbiotinyl thionine (BBT) by means of voltammetric techniques. Thionine is an electroactive compound and has two amino groups that are necessary for the reaction with a biotinylation reagent. The biotinylation of thionine produces a new reagent with two biotin moieties at each end of thionine. Three BBTs of different lengths of the spacer that connects the biotin moiety to the thionine moiety were prepared. The avidin-biotin binding assay was achieved by measuring the electrode response of the thionine moiety in BBT. The binding affinity and the conformation of complex, which depended on the length of spacer, are discussed. BBT in which the spacer is shortest (BBT-S, distance between carbonyl group of the two biotin moieties: 11 Å) binds with only one avidin molecule. BBT with medium length of spacer (BBT-M, 28.8 Å) forms the complex with two avidin molecules. BBT with the longest spacer (BBT-L, 46.6 Å) allows binding with two avidin molecules as well as intramolecular binding within one avidin molecule. The affinity constants of BBT-S, BBT-M and BBT-L for avidin were estimated to be 7.0 × 10¹² M⁻¹, 3.2 × 10¹² M⁻¹ and 4.0 × 10¹² M⁻¹, respectively.     

Measurement of Gamma-Rays from 11ΛB and 12ΛC

From the ^12 C（π^＋,K^＋）^12 AC reaction the γ -rays of 261.6±0.24 ke V（7/2^＋ →5/2^＋）and 1481.7±0.7 ke V（1/2^＋ →5/2^＋） of ^11 A B,and 2667.3±2.8 keV（1^- 2 → 2^- 1）of ^12 A C hypernuclei have been identified using a large germanium detector array Hyperball2 at K6 beam line of KEK. The observed energies of the transitions 1481.7keV and 261.6 keV are significantly different from the values predicted by the shell model using the △ and SN parameters determined from the ^7 △ Li data.     

Effects of hyperons in binary neutron star mergers

Numerical simulations for the merger of binary neutron stars are performed in full general relativity incorporating both nucleonic and hyperonic finite-temperature equations of state (EOS) and neutrino cooling. It is found that even for the hyperonic EOS, a hypermassive neutron star is first formed after the merger for the typical total mass ≈2.7M(⊙), and subsequently collapses to a black hole (BH). It is shown that hyperons play a substantial role in the postmerger dynamics, torus formation around the BH, and emission of gravitational waves (GWs). In particular, the existence of hyperons is imprinted in GWs. Therefore, GW observations will provide a potential opportunity to explore the composition of neutron star matter.     

Sarcospan: ultrastructural localization and its relation to the sarcoglycan subcomplex

Sarcospan is a 25 kDa transmembrane component of dystrophin-associated glycoprotein. We generated a rabbit polyclonal antibody against synthetic peptide of the N-terminal domain of human sarcospan. Using this antibody we investigated the localization of sarcospan and its spacial relation to the components of sarcoglycan subcomplex in normal human skeletal myofibers by immunofluorescent microscopy and immunogold electron microscopy. In immunofluorescence the reaction was observed continuously at the myofiber surface. Ultrastructurally the gold signals of rabbit anti sarcospan antibody were present along the muscle plasma membrane, mainly at its inside surface. The triple immunogold labeled muscle samples showed that the signals of rabbit or sheep polyclonal anti alpha-, beta-, gamma- and delta-sarcoglycan antibodies and/or mouse monoclonal anti beta-, gamma- and delta-sarcoglycan antibodies were located along the muscle plasma membrane, and the cluster formation of different two or three sarcoglycan molecules was observed. The triple immunogold labeling also revealed that the signal of sarcospan molecules are present frequently in doublets and/or triplets with the components of sarcoglycan subcomplex, resulting in the cluster formation of signals of sarcoglycan and sarcospan molecules. The result of this study showed that sarcospan was expressed at the myofiber surface and that sarcospan was present in close association with alpha-, beta-, gamma- and delta-sarcoglycans and formed a functional unit with sarcoglycan subcomplex.     

Ecosystems perspective on financial networks: Diagnostic tools

The world economy consists of highly interconnected and interdependent commercial and financial networks. Here, we develop temporal and structural network tools to analyze the state of the economy and the financial markets. Our analysis indicates that a strong clustering can be a warning sign. Reduction in diversity, which was an essential aspect of the dynamics surrounding the financial markets crisis of 2008, is seen as a key emergent feature arising naturally from the evolutionary and adaptive dynamics inherent to the financial markets. Similarly, collusion amongst construction firms in a number of regions in Japan in the 2000s can be identified with the formation of clusters of anomalous highly connected companies. © 2013 Wiley Periodicals, Inc. Complexity 19: 22–36, 2013