Status of heavy element research using a gas-filled recoil separator at RIKEN

A gas-filled type of recoil separator for heavy element research was installed at an experimental hall of RIKEN Linear Accelerator facility to realize getting higher intensity of primary beam and long beam time. Performance of the separator was studied using target recoils and various nuclear reactions. The results show the high performance of the separator for heave element research. As an application of the GARIS, production and identification of an isotope of the 110th element ²⁷¹[110] have been performed using the ²⁰⁸Pb(⁶⁴Ni,1n)²⁷¹[110] reaction. Three decay chains coincide well both in decay times and energies with the ones reported by the group of SHIP experiment at GSI, Germany. Our results provide a confirmation of the synthesis of an isotope ²⁷¹[110] of element 110.     

Ethylene polymerization by chromium complexes with phosphorous‐bridged bisphenoxy ligand

Chromium catalysts combined with phosphorous‐bridged bisphenoxy ligands were found to be highly active for ethylene polymerization. The most efficient catalyst precursor among them, generated by combining bis[3‐tert‐butyl‐5‐methyl‐2‐hydroxyphenyl](phenyl)phosphine hydrochloride ( 1a ) and CrCl₃(THF)₃, was characterized. X‐ray analysis of (3‐tert‐butyl‐5‐methyl‐2‐phenoxy)(3‐tert‐butyl‐5‐methyl‐ 2‐hydroxyphenyl)(phenyl)phosphine bis(tetrahydrofuran)chromium dichloride ( 6 ), obtained by the reaction of 1a and CrCl₃(THF)₃ in the presence of NaH, revealed a unique structure in which one phenol moiety of the bisphenol did not coordinate to the chromium center. Complex 6 showed higher activities than those observed in the in situ catalyst system. Polyethylene of various molecular weights was obtained with differing activators. The highest activity (113.5 kg mmol (cat)^?1 h^?1) was observed when TIBA/TB was used as a cocatalyst. A medium molecular weight polymer with narrow molecular weight distribution (M_w = 128,700, M_w/M_n = 1.8) was obtained using a 6 ‐TIBA/B(C₆F₅)₃ system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3668–3676, 2007     

Self-assembled lipid nanotube hosts: The dimension control for encapsulation of nanometer-scale guest substances

Supramolecular nanotube hosts with precisely controlled inner or outer diameters have been synthesized by self-assembly of unsymmetrical bolaamphiphilic monomers or glucopyranosylamide lipids, respectively. Time-resolved fluorescent measurement using 8-anilinonaphthalene-1-sulfonate (ANS) as a probe revealed that the water confined in a cardanyl-β-D -glucopyranoside lipid nanotube has relatively lower solvent polarity corresponding to that of propanol than bulk water. Extensively developed hydrogen bond networks also characterize the confined water in comparison to the case in bulk water. Encapsulation ability of the glucopyranosylamide lipid nanotube has been examined by filling the lyophilized LNTs with gold or silver nanoparticles, ferritin, or magnetic crystals. Filling the unsymmetrical bolaamphiphile nanotube possessing positively charged inner surfaces with negatively charged polymer beads or ferritin proved to be successful without depending on capillary action. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5137–5152, 2006     

Hydration Structure Around the Carboxyl Group Studied by Neutron Diffraction with 12C/13C and H/D Isotopic Substitution Methods

Time-of-Flight (TOF) neutron diffraction measurements have been carried out on aqueous 8 mol% sodium acetate solutions in D₂O. Scattering cross sections that were observed for sample solutions involving ¹²C/¹³C and H/D isotopically substituted acetate ions were used to derive the first-order difference functions, Δ_H(Q) and Δ_C(Q), and corresponding distribution functions, G _H(r;r) and G _C(r;r), which describe the environmental structure around the methyl and the carboxyl groups within the acetate ion, respectively. Structural parameters concerning the first hydration shell of the carboxyl group within the acetate ion were obtained through the least squares fit to the observed intermolecular difference function, Δ_C ^inter(Q). The nearest neighbor C _O...D _W1 (C_O: carboxyl carbon atom, D_W1: water deuterium atom) distance, r(C _O...D _W1 ), and the angle, ∠ C _O ...D _W1 -O _W (O _W : water oxygen atom), were determined to be 2.63(1) Å and 120(1)°, respectively. The coordination number, n(C _O ...D _W1 ), was obtained to be 4.0(1). These results are consistent with the hydration structure in which water molecules in the first hydration shell of the carboxyl group are hydrogen-bonded with oxygen atoms of the carboxyl group.     

Studies on analgesic oligopeptides. VI. Further studies of synthesis and biological properties of tripeptide alkylamides, Tyr-D-Arg-Phe-X

Nine analogs based on a structure of Tyr-D-Arg-Phe-X (X = alkylamides or alkylhydrazide containing electron-withdrawing atoms or groups) were newly synthesized and their biological properties were examined by the opioid receptor binding properties of mu-, delta- and kappa-receptors, guinea-pig ileum (GPI) assay and analgesic activity in the tail pinch test after subcutaneous administration in mice. Analogs with X = NHCF2CF3, Sar-ol, or NH(CH2)2CN showed potent activities in the GPI and analgesic assays and high affinity for mu-receptor. An analog with X = taurinamide was found to possess 4-fold higher mu-receptor selectivity than that of [D-Ala2, MePhe4, Gly-ol5]enkephalin (DAGO). The receptor binding properties of previously reported analogs [Chem. Pharm. Bull., 33, 1528 (1985); ibid., 33, 4865 (1985); ibid., 36, 4834 (1988)] were also examined for overall discussion of the structure-activity relationships of this series of tripeptide amides.     

Formal synthesis of tubelactomicins via a transannular Diels-Alder approach

A formal synthesis of the antimicrobial tricyclic macrolides, tubelactomicins A and E, featured by a transannular Diels-Alder (TADA) approach, has been explored. The key issue for the transannular cyclization was the synthesis of a 24-membered macrolactone equipped with all the requisite functionalities, which has been achieved using an intramolecular Hiyama cross-coupling strategy. The Hiyama coupling reaction spontaneously triggered off the TADA reaction. From the endo-TADA adduct, formal syntheses of tubelactomicins A and E were achieved. The 24-membered macrolactone formation was also achieved via an intramolecular ring-closing metathesis approach.     

Stereospecific polymerization of isobutyl vinyl ether catalyzed by calcined iron sulfate

The polymerization of isobutyl vinyl ether was studied in a heterogeneous system using iron (II) sulfate calcined in air at various temperatures as a catalyst. The maximum activity was shown by the catalyst calcined at 700°C, which effected the polymerization at room temperature in a few seconds, while the sulfate treated at 750°C was totally inactive. Poly(vinyl ethyl ether) was also obtained by the FeSO₄ (700°C) catalyst at room temperature. This catalyst formed the crystalline polymer (melting temperature 135–138°C) when the reaction was performed in toluene as solvent at room temperature. Poisoning experiments with Hammett indicators were carried out with the FeSO₄ (700°C) catalyst. The treatment with n-butylamine rendered it inactive in the reaction of isobutyl vinyl ether, while its catalytic activity was little affected by dicinnamalacetone. On the basis of the observed results, the nature of active sites of catalyst is discussed.     

Synthesis and reactivity of dimeric Ar'TlTlAr' and trimeric (Ar"T1)3 (Ar', Ar" = bulky terphenyl group) thallium(I) derivatives: Tl(I)-Tl(I) bonding in species ligated by monodentate ligands

The synthesis and characterization of three new organothallium(I) compounds are reported. Reaction of (Ar'Li)(2) (Ar' = C(6)H(3)-2,6-(C(6)H(3)-2,6-Pr(i)(2))(2)) and Ar"Li (Ar" = C(6)H(3)-2,6-(C(6)H(3)-2,6-Me(2))(2)) with TlCl in Et(2)O afforded (Ar'Tl)(2) (1) and (Ar' 'Tl)(3) (2). The "dithallene" 1 is the heaviest group 13 dimetallene and features a planar, trans-bent structure with Ar'Tl-Tl = 119.74(14) degrees and Tl-Tl = 3.0936(8) A. Compound 2 is the first structurally characterized neutral, three-membered ring species of formula c-(MR)(3) (M = Al-Tl; R = organo group). The Tl(3) ring has Tl-Tl distances in the range ca. 3.21-3.37 A as well as pyramidal Tl geometries. The Tl-Tl bonds in 1 and 2 are outside the range (2.88-2.97 A) of Tl-Tl single bonds in R(2)TlTlR(2) compounds. The weak Tl-Tl bonding in 1 and 2 leads to their dissociation into Ar'Tl and Ar' 'Tl monomers in hexane. The Ar'Tl monomer behaves as a Lewis base and readily forms a 1:1 donor-acceptor complex with B(C(6)F(5))(3) to give Ar'TlB(C(6)F(5))(3), 3. Adduct 3 features an almost linear thallium C(ipso)-Tl-B angle of 174.358(7) degrees and a Tl-B distance of 2.311(2) A, which indicates strong association. Treatment of 1 with a variety of reagents resulted in no reactions. The lower reactivity of 1 is in accord with the reluctance of Tl(I) to undergo oxidation to Tl(III) due to the unreactive character of the 6s(2) electrons.     

Singular value decomposition applied to the compression of T3 amplitude for the coupled cluster method

We apply the singular value decomposition to compress the degrees of freedom of T3 amplitude for the CCSDT-1 method (compressed CCSDT-1). This method enables us to make the number of the T3 amplitudes less than that of the T2 amplitudes, making CCSDT-1 calculations much less expensive without losing accuracy. We perform test calculations on some atoms and molecules to investigate the applicability of this method. Computational results for the electronic energies as well as timings of these calculations are presented.     

Formulation design of ointment base suitable for healing of lesions in treatment of bedsores

We intended to develop a desired ointment base suitable for treatment of bedsores including the proliferation of granulation and epidermis. The main bedsore bacteria detected in our hospital were S. aureus in gram-positive coccus and P. aeruginosa in gram-negative bacillus. As the macrogol ointment (MO) was found to have bactericidal effects on these bacteria, MO was adopted as the base for the objective ointment. To improve the properties of the ointment base such as regulating the humidity of the exudation and controlling the release of antibiotics formulated in the ointment, co-formulating effects of various additives to MO were evaluated. The sustained release function of the ointment base was obtained by adding hydrophilic petrolatum (HP) to MO. However, the resultant ointment was found to have a poor humidity regulating property. On the other hand, MO containing 5% of hydroxypropyl cellulose (HPC) showed both the humidity regulating and the controlled drug releasing properties. It was considered that HPC particles dispersed in the ointment could be swelled by absorbing water to form a gel network. The curd tension meter tests for the ointments prepared with the various polymers showed that the MO-HPC base, which showed the highest sustained drug releasing property, was found to have the highest hardness. This result means that HPC formulated into the base forms the most rigid gel structure to resist the erosion of the ointment and to control the drug release.