Effect of acetylene on the γ-radiation-induced polymerization of ethylene

The effects of acetylene on the γ-radiation-induced polymerization of ethylene were studied from the viewpoint of the gaseous products and polymer structure. The experiments were carried out under a pressure of 400 kg/cm²; the temperature was 30°C; the does rate was 1.1 × 10⁵ rad/hr; and the acetylene content was 0–20%. The solid polymer was obtained in the polymerization of ethylene containing 2.2% acetylene, while the monomer containing 19.7% acetylene gave a yellowish viscous oil. The polymer yield and molecular weight decreased remarkably with acetylene content. The main gaseous product was hydrogen, and trace amounts of butane, butene-1, butadiene-1,3, and benzene and its derivatives were also observed. The rate of formation of hydrogen was almost independent of acetylene content and there was no difference in acetylene contents before and after the irradiation was found. The infrared spectra of the polymers showed the presence of vinylidene, trans-vinylene, and terminal vinyl unsaturations, 1,4-disubstituted benzene, and carbonyl groups. The contents of trans-vinylene, terminal vinyl, and methyl groups increased with acetylene content, and that of vinylidene was independent of acetylene content. The monomer reactivity ratios of ethylene and acetylene were evaluated as 45.5 and 66.0, respectively. On the basis of the results, the effects of acetylene on the γ-radiation-induced polymerization of ethylene were discussed.     

SmI2-induced reductive cyclization of optically active β-alkoxyvinyl sulfoxides with aldehyde

SmI₂-induced reductive cyclization of optically active (E)- and (Z)-β-alkoxyvinyl sulfoxides with aldehyde was developed for the construction of several stereoisomers of tetrahydropyran derivatives.     

An analytical method for irinotecan (CPT-11) and its metabolites using a high-performance liquid chromatography: parallel detection with fluorescence and mass spectrometry

Irinotecan or 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) is an anticancer pro-drug used in the treatment of many types of cancer. We describe here the validation of an analytical method for CPT-11 and its metabolites, including an active metabolite, 7-ethyl-10-hydroxycamptothecin (SN-38), its glucuronidated form, SN-38G, and several cytochrome P450 3A-mediated products such as 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]carbonyloxycamptothecin (APC) using a high-performance liquid chromatography connected to parallel fluorescence and mass spectrometry detection systems. This method is characterized as follows: (1) simple extraction of the analytes from biomaterials with perchloric acid/methanol; (2) sensitive quantitation of major metabolites (SN-38G, SN-38 and APC) with a fluorescence detector (FLD), where the limits of quantitation by FLD were 2.5 ng/mL for SN-38G and APC, 5 ng/mL for CPT-11 and 1 ng/mL for SN-38, respectively; (3) parallel selective monitoring of the metabolites including minor metabolites with a mass selected detector (MSD). There was no observed interference by other drugs expected to be co-administered. This method showed its usefulness by identifying a novel metabolite produced in human hepatic microsomes. The results indicate that this combination of FLD and MSD enables a highly selective analysis of CPT-11 and its metabolites, and is useful for studies both in vivo and in vitro.     

Charge carrier transport properties in polymer liquid crystals containing oxadiazole and amine moieties in the same side chain

Steady-state and transient photocurrent measurements were carried out to study the charge carrier transport properties of polymer liquid crystal (LC) containing oxadiazole (OXD) and amine moieties in the same side chain. The steady-state photocurrent measurement with asymmetric electrodes of ITO and Al and a short penetration depth of the illumination light indicated that both electrons and holes can be transported in this film. The transient hole photocurrent observed by time-of-flight (TOF) experiments was dispersive at room temperature. The hole drift mobility significantly depended on temperature and electric field and was determined to be 6.1 x 10(-8) cm2/Vs at a field of 9.1 x 10(5) V/cm. According to the disorder formalism, the Gaussian width of the density of states was determined to be 170 meV for holes. Despite the indication of possible electron transport in this film, we could not determine the electron mobility by TOF experiments due to strong dispersive photocurrent. We discuss the present charge transport properties of the film in relation to a large dipole attributed to an electrical push-pull structure of p-dimethylaminophenyl-substitited OXD moiety in polymer LC and its electroluminescent properties.     

Production of scalar Higgs and pseudoscalar Higgs in multi-Higgs doublet models at \gamma\gamma colliders

We present the effects of heavy CP-even (H) and CP-odd (A) Higgs bosons on the production cross section of the process at the energy around the mass poles of the Higgs bosons. It is found that interference between H and A with small mass gap, as well as the ones between Higgs bosons and continuum, contributes to the cross section, if the photon beams are polarized and if we observe the helicity of the top quarks. It is demonstrated in the framework of the minimal supersymmetric extension of the standard model that the H and A contributions can be sizable at future colliders for small values of . The methods to measure the CP-parity of the Higgs boson are also presented. The statistical significance of detecting the Higgs signals and measuring the Higgs CP-parity is evaluated. Received: 16 December 1999 / Revised version: 30 January 2000 / Published online: 6 April 2000     

A Complete Frequency-Field Chart for the Antiferromagnetic Resonance in MnF2

Antiferromagnetic resonance (AFMR) measurements on a well characterized single crystal sample of MnF₂ have been performed using various kinds of millimeter and submillimeter sources up to 570 GHz and a superconducting magnet up to 20 T. All the AFMR modes predicted from the theory have been observed. We report a complete frequency-field chart for these AFMR modes.     

Synthesis of Hyperbranched Aminopolysaccharides

Sugar dihydroozaxole monomers with two free hydroxyl groups undergo acid-catalyzed polymerization to hyperbranched aminopolysaccharides [Eq. (a)]. Their molecular weights were determined by the light-scattering method to be between 2.3×10⁵ and 7.6×10⁵. The degree of branching determined by ¹H NMR spectroscopy after reaction with [iPr₂Si(Cl)]₂O is close to the ideal value. Ts=MeC₆H₄SO₂, CSA=10-camphorsulfonic acid.     

Preparation of highly oriented poly-diacetylene films with ion beam irradiation

Abstract

Substituting metallic or rare-earth atoms or removing O in the superconductor YBa₂Cu₃O₇ usually has a strong effect on the superconducting properties. We have made extensive XAFS studies on Co, Fe, Ni, Zn, Gd, and Pr substituted materials including some thin film samples. In nearly all cases, significant distortions are found. Although the lattice constant change is small (< 0.05 Å) the local distortions can be significant larger (～ 0.1 to 0.3 Å). The observed large local distortions of the lattice together with a change in the charge distribution at a site indicate that the interior of the unit cell is easily distorted. The correlation of a strong Tc suppression with large local distortions suggests that distortions of the nearby layers must play a significant role in models for superconductivity in high Tc materials.