Synthesis of chiral 1-substituted tetrahydroisoquinolines by the intramolecular 1,3-chirality transfer reaction catalyzed by Bi(OTf)3

The intramolecular 1,3-chirality transfer reaction of chiral amino alcohols 1 with 99% ee was developed to construct chiral 1-substituted tetrahydroisoquinoline 2. Bi(OTf)(3) (10 mol %)-catalyzed cyclization of 1 (R = H) afforded (S)-1-(E)-propenyl tetrahydroisoquinoline 2 (R = H) in 83% yield with a ratio of 98:2. The stereochemistry at the newly formed chiral center was produced by a syn S(N)2'-type process. In this reaction, the substituent on the benzene ring of 1 significantly affected the reactivities and selectivities. A plausible reaction mechanism was proposed.     

Metallic transport in a monatomic layer of in on a silicon surface

We have succeeded in detecting metallic transport in a monatomic layer of In on an Si(111) surface, Si(111)-sqrt[7]×sqrt[3]-In surface reconstruction, using the micro-four-point probe method. The In layer exhibited conductivity higher than the minimum metallic conductivity (the Ioffe-Regel criterion) and kept the metallic temperature dependence of resistivity down to 10?K. This is the first example of a monatomic layer, with the exception of graphene, showing metallic transport without carrier localization at cryogenic temperatures. By introducing defects on this surface, a metal-insulator transition occurred due to Anderson localization, showing hopping conduction.     

Combination of two fat saturation pulses improves detectability of glucose signals in carbon-13 MR spectroscopy

In order to improve the fat suppression performance of in vivo (13)C-MRS operating at 3.0 Tesla, a phantom model study was conducted using a combination of two fat suppression techniques; a set of pulses for frequency (chemical shift) selective suppression (CHESS), and spatial saturation (SAT). By optimizing the slab thickness for SAT and the irradiation bandwidth for CHESS, the signals of the -(13)CH(3) peak at 49 ppm and the -(13)CH(2)- peak at 26 ppm simulating fat components were suppressed to 5% and 19%, respectively. Combination of these two fat suppression pulses achieved a 53% increase of the height ratio of the glucose C1β peak compared with the sum of all other peaks, indicating better sensitivity for glucose signal detection. This method will be applicable for in vivo (13)C-MRS by additional adjustment with the in vivo relaxation times of the metabolites.     

Correlation of antithrombogenicity and heat treatment for layer-by-layer self-assembled polyelectrolyte films

Antithrombogenic films with high durability were fabricated in a wet process. Antithrombogenicity was achieved with polyelectrolyte multilayer thin film prepared from poly(vinyl alcohol)-poly(acrylic acid) (PVA-PAA) blends, deposited in alternate layers with poly(allylamine hydrochloride) (PAH). Film durability, assessed by abrasion resistance and water resistance, was enhanced by forming cross-links via amide bonds induced by heat treatment of the film. The film was found to be resistant to protein adsorption, as measured by the amount of fibrinogen adsorbed from an aqueous solution. The antithrombogenic efficacy was assessed in ex vivo experiments by the ability of stainless steel mesh, coated with the polyelectrolyte and inserted into a pig blood vessel, to inhibit thrombus formation. Mesh coated with the polyelectrolyte did not reduce blood flow over a period of 15 min, whereas with uncoated mesh blood flow stopped within 6 min because of blood vessel blockage by thrombus formation.     

Synthesis and characterization of polydimethylsiloxane-cyanopropyltriethoxysilane-derived hybrid coating for stir bar sorptive extraction

New inorganic–organic hybrid materials were synthesized by hydrolysis and condensation of cyanopropyltriethoxysilane (CNPrTEOS) and polydimethylsiloxane (PDMS) in the presence of hydrochloric acid, HCl catalyst and methyl trimethylmethoxysilane as precursor via sol–gel method and coated on glass encased stir bar for use in stir bar sorptive extraction (SBSE). The cyano part provides polar moiety, which may improve the extraction of polar analytes. The physico-chemical properties and extraction ability of PDMS-CNPrTEOS-derived hybrid coatings can be fine tuned via manipulation of solvents (tetrahydrofuran (THF)-based and dichloromethane (DCM)-based) and PDMS-CNPrTEOS molar concentrations during the sol synthesis. Clear, homogeneous PDMS-CNPrTEOS-derived hybrid sols were obtained using THF and DCM at optimized molar ratios. The optimized molar ratios of THF:CNPrTEOS and THF:PDMS were 5:1 and 25:1, respectively. The optimized molar ratios of DCM:CNPrTEOS and DCM:PDMS were 10:1 and 70:1, respectively. FTIR spectrum showed that the intensity of the CN peak increased with increasing content of CNPrTEOS in the PDMS;CNPrTEOS-derived hybrid. The Field Emission Scanning Electron micrographs of prepared coatings revealed smooth, homogenous surfaces and crack-free coatings with film thickness of 200 nm to 2.5 μm attributing to different solvent types. All coatings prepared were thermally stable at temperature higher than 200 °C. The DCM-based PDMS-CNPrTEOS-derived coating shows more advantages in terms of physical characteristics and extraction ability compared to THF-based PDMS-CNPrTEOS-derived coatings due to higher cyano part content and its thicker coating. The PDMS-CNPrTEOS-derived hybrid coatings can be used as extraction sorbent for analysis of non steroidal anti-inflammatory drugs namely ketoprofen and diclofenac sodium in SBSE.     

Relationship between channel and sorption properties in coordination polymers with interdigitated structures

Porous coordination polymers constructed from Zn²⁺ and isophthalate with linear bipyridyl‐type ligands were synthesized. [Zn(ip)(bpb)]_n (CID‐21; ip=isophthalate, bpb=1,4‐bis(4‐pyridyl)benzene), [Zn(ip)(bpt)]_n (CID‐22; bpt=3,6‐bis(4‐pyridyl)‐1,2,4,5‐tetrazine), and [Zn(ip)(bpa)]_n (CID‐23; bpa=1,4‐bis(4‐pyridyl)acetylene) all have interdigitated structures of layers and similar void volumes (≈27 %). In these compounds, 1D bottleneck‐type channels run along the perpendicular direction of the layer stacking and their properties are strongly dominated by the dipyridyl linker ligands. Because of the difference in packing of 2D layers, CID‐21 and CID‐22 have relatively rigid porous structures, whereas CID‐23 has greater flexibility, as indicated by the results of powder X‐ray diffraction studies. The micropores of CID‐22 surrounded by tetrazine moieties adsorb polar molecules, such as methanol and water. The higher affinity of CID‐22 for water than CID‐21 is supported by a theoretical study. The 1D channel of CID‐23 is wider than that of the other two compounds, which enables the incorporation of aromatic molecules. This is because the shape of the bpa linker ligand generates a wider pore diameter (8.6 Å). Only CID‐23 can adsorb a benzene molecule and the isotherm of benzene has a gate‐opening‐type profile. This offers proof of the guest accommodation process through large structural transformation from a nonporous to a porous structure. The flexibility and restricted pore space of CID‐23, at 298 K, allows only benzene, but not cyclohexane, to enter the channels. The porous structure exhibits clear selectivity for these similar guests. The incorporation of an elongated dipyridyl linker ligand in the 2D coordination layers provides a strategy for the design of microporous compounds with different flexibilities, microporous environments, and separation abilities.     

Direct Measurement of 12C+4He Fusion Cross Section at E cm = 1.5 MeV at KUTL

¹²C+⁴He fusion reaction at E _cm  = 0.3 MeV is one of the main reaction in ⁴He-burning in stars, and is very important in nuclear synthesis. However the fusion cross section has not been determined yet in spite of 40 years efforts in the world. Recently we succeeded in the measurement at 1.5 MeV. We have a plan to make direct measurement of the total fusion cross section down to 0.7 MeV at Kyushu University Tandem accelerator Laboratory (KUTL), and to determine the cross section at 0.3 MeV by extrapolation.     

Measurement of 4He(12C,16 O)γ Reaction in Inverse Kinematics

A cross section measurement employing a direct ¹⁶O detection method for the reaction energies from E _cm = 2.4 to 0.7 MeV is planned at Kyushu University Tandem Laboratory. To perform this experiment and to obtain quantitative information about the cross section to within an error of 10%, we have developed several instruments, including a blow-in type windowless gas target and a ionization chamber. A target thickness of 24 × 3.9 Torr cm was achieved using the developed gas target. The particle identification was successfully performed by using the energy deposit in the ionization chamber. Experiments were performed at E _cm = 2.4 and 1.5 MeV using the developed instruments and the cross sections were obtained.     

Abilities of Antioxidants to Eliminate the Peroxyl Radical Derived from 2,2′-Azobis(2-Amidinopropane) Dihydrochloride (AAPH)

Electron spin resonance (ESR) of 5-(2,2-dimethyl-1,3-propoxy cyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO) spin adducts of free radicals derived from the UV irradiation of 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) under rapid scanning condition was examined. The ESR signal obtained was the superposition of two spectra, the spin adduct of the alkoxyl radical [CYPMPO-ORa, Ra = C(CH₃)₂-C(⁺NH₂Cl^?)NH₂] and the peroxyl radical (CYPMPO-OORa). The decay rate of CYPMPO-OORa was 8,400 times that of CYPMPO-ORa. The order of the k _SB/k _ST values (the slope of the Stern–Volmer’s plot) for the peroxyl radical (RaOO·) was l-ascorbic acid > caffeic acid > rutin ~ Trolox ~ (+)-catechin ~ glutathione (reduced), which was almost the same order as that for the alkoxyl radical (RaO·). Though the k _SB/k _ST value of each antioxidant for the peroxyl radical was about half of that for the alkoxyl radical, the ratios of the values of antioxidants to that of trolox (the relative ORAC values) were almost the same between the peroxyl and alkoxyl radicals. The relative oxygen radical absorbance capacity (ORAC) values of polyphenols estimated by the ORAC-ESR assay using both peroxyl and alkoxyl radicals were smaller than those by the ORAC-FL assay.     

Measurement and simulation of the cross sections for nuclide production in natW and 181Ta targets irradiated with 0.04- to 2.6-GeV protons

The cross sections for nuclide production in thin ^natWand ¹⁸¹Ta targets irradiated by 0.04–2.6-GeV protons have been measured by direct γ spectrometry using two γ spectrometers with the resolutions of 1.8 and 1.7 keV in the ⁶⁰Co 1332-keV γ line. As a result, 1895 yields of radioactive residual product nuclei have been obtained. The ²⁷Al(p, x)²²Na reaction has been used as a monitor reaction. The experimental data have been compared with the MCNPX (BERTINI, ISABEL), CEM03.02, INCL4.2, INCL4.5, PHITS, and CASCADE07 calculations.