Self‐Assembled Multilayer‐Stabilized Nickel Nanoparticle Catalyst for Ligand‐Free Cross‐Coupling Reactions: in situ Metal Nanoparticle and Nanospace Simultaneous Organization

We have developed a conceptually and methodologically novel self‐assembled multilayer nickel nanoparticle (NP) catalyst – sulfur‐modified gold‐supported Ni NPs (SANi) – for organic synthesis. The SANi catalyst was easily prepared through a three‐step procedure involving simultaneous in situ metal NP and nanospace organization. This unique method does not require any conventional preformed template for immobilizing and stabilizing NPs. SANi catalyzes carbon‐carbon bond‐forming cross‐coupling, Kumada coupling, and Negishi coupling reactions under ligand‐free conditions and can be used repeatedly for these reactions. Physical analysis of SANi showed that the active species in these reactions are self‐assembled multilayer zerovalent Ni NPs with a size of ∼3 nm.

     

Condensation reactions of phenolic resins. VI. Dependence of the molecular association of 2,4,6‐trihydroxymethylphenol on the concentration in an aqueous alkaline medium

The concentration dependence of the molecular association of 2,4,6‐trihydroxymethylphenol (THMP) as a model compound for phenol–formaldehyde resin was studied. ¹³C‐NMR spin–lattice relaxation time (T₁) measurements indicated that the molecular interactions were influenced by the concentration of THMP. Plots of T₁ versus the concentration revealed an inflection point around 1.2 mol/L. Molecular orbital calculations of the THMP molecules implied the following features of the molecular interactions: in the concentration range below 1.0 mol/L, THMP existed as a single molecule, and then at a higher concentration, self‐association started. At concentrations higher than 1.5mol/L, almost all the THMP molecules were bimolecularly associated, and the formation of larger clusters was initiated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2849–2854, 2007     

Biosynthetic Machinery of Diterpene Pleuromutilin Isolated from Basidiomycete Fungi

The diterpene pleuromutilin is a ribosome‐targeting antibiotic isolated from basidiomycete fungi, such as Clitopilus pseudo‐pinsitus. The functional characterization of all biosynthetic enzymes involved in pleuromutilin biosynthesis is reported and a biosynthetic pathway proposed. In vitro enzymatic reactions and mutational analysis revealed that a labdane‐related diterpene synthase, Ple3, catalyzed two rounds of cyclization from geranylgeranyl diphosphate to premutilin possessing a characteristic 5–6–8‐tricyclic carbon skeleton. Biotransformation experiments utilizing Aspergillus oryzae transformants possessing modification enzyme genes allowed the biosynthetic pathway from premutilin to pleuromutilin to be proposed. The present study sets the stage for the enzymatic synthesis of natural products isolated from basidiomycete fungi, which are a prolific source of structurally diverse and biologically active terpenoids.     

Synthesis and polymerization of methacrylate bearing a phosphorylcholine, analogous moiety

Summary A new type of methacrylate bearing a phosphorylcholine analogous moiety, 2-[2'-(trimethylammonium)-1-methylethyl-phosphoryl]ethyl methacrylate (TMPM) was synthesized. TMPM was radically homopolymerized and copolymerized with BMA to obtain the polymers. The critical micelle concentration (CMC) of TMPM was 4.9 × 10⁻² mol/l according to the fluorescent probe method. Received: 11 June 2001/Revised version: 30 July 2001/Accepted: 31 July 2001     

Chromium Oxycarbide Thin Films Prepared by Inductively Coupled Radio-Frequency Plasma-Assisted Magnetron Sputtering

Chromium oxycarbide films were prepared on SUS 304 stainless steel at temperatures of ∼673 K using the inductively coupled radio-frequency plasma-assisted magnetron-sputtering technique. An inductively coupled 13.56 MHz electromagnetic field with a power of 40 W was supplied to excite the glow discharge, and a direct-current power of 700 W was supplied to sputter a 99.9% chromium target in an Ar/CO₂/CH₄ mixture and in Ar/CO mixture. Electron probe microanalysis revealed that the film contained chromium, oxygen, and carbon. Vickers microhardness of the film was determined to be >1.96 × 10¹⁰ Pa. X-ray diffractometry measurements revealed that the film structure was cubic, and the lattice constant was a ₀= 0.42 nm. This structure was almost the same as that of chromium oxycarbide, Cr₂CO, (rock-salt structure, lattice constant of 0.413 nm). The corrosion resistance of the SUS 304 stainless steel to 1 kmol/m³ H₂SO₄ at 293 K was improved by coating it with a Cr(C,O) film to a thickness of 5.92 μm.     

Use of NIR spectroscopy for estimation of FA composition of soy flour

The feasibility of NIR spectroscopy for the determination of FA composition in soy flour was examined. NIR spectra were obtained for a small amount of soybean powder (about 8 mg) in a modified single-grain cup using an NIR instrument by scanning the wavelengths from 1100 to 2500 nm at 2-nm intervals. The relationship between the NIR spectral patterns of soybean powder and the FA compositions was examined: As the linoleic acid ratio increased, the NIR absorbance at 1708 nm, where the linoleic acid moiety has an absorption band, became stronger downward in the second-derivative NIR spectra. The correlation coefficients between the standardized NIR readings at 1708 nm and the linoleic acid ratio or the oleic acid ratio in the FA composition of soy flour were −0.853 and 0.877, respectively. A rough estimation of the linoleic acid moiety or oleic acid moiety in soy flour could be successfully carried out with even a very small amount of soy flour according to the NIR spectral pattern due to the wavelength assignments of moieties.     

Formation of Silicalite-1 in Channels of Novel SiO2–ZrO2 Porous Glass Tubes Used as Both a Silica Source and a Substrate

Silicalite-1 has been prepared using a novel SiO₂–ZrO₂ porous glass tube as both a silica source and a substrate. The SiO₂–ZrO₂ glass tube was found to possess sufficient physical strength to enable practical use as a separation and catalytic membrane after silicate-1 deposition within its channel. This is in contrast to porous SiO₂ glass which cannot be used to synthesize a silicalite-1 deposited membrane with enough physical strength to perform gas permeance measurements.     

Microstructure and mechanical properties of Al_3Ti-based alloys in Al-Ti-Mo-X quaternary systems

A part of Al-Ti-Mo-Cr quaternary phase diagram is constructed for the microstructure control of D022-Al3Ti or its derivative, L12-(Al,Cr)3Ti, -based alloys. It was found that quaternary bcc phase equilibrates with either D022-Al3Ti or L12-(Al,Cr)3Ti, or both, exist in large compositional areas. The mechanical properties is strongly affected by precipitates appearing, and presumably alloy microstructures.     

An evaluation tool for FKBP12-dependent and -independent mTOR inhibitors using a combination of FKBP-mTOR fusion protein, DSC and NMR

Mammalian target of rapamycin (mTOR), a large multidomain protein kinase, regulates cell growth and metabolism in response to environmental signals. The FKBP rapamycin-binding (FRB) domain of mTOR is a validated therapeutic target for the development of immunosuppressant and anticancer drugs but is labile and insoluble. Here we designed a fusion protein between FKBP12 and the FRB domain of mTOR. The fusion protein was successfully expressed in Escherichia coli as a soluble form, and was purified by a simple two-step chromatographic procedure. The fusion protein exhibited increased solubility and stability compared with the isolated FRB domain, and facilitated the analysis of rapamycin and FK506 binding using differential scanning calorimetry (DSC) and solution nuclear magnetic resonance (NMR). DSC enabled the rapid observation of protein-drug interactions at the domain level, while NMR gave insights into the protein-drug interactions at the residue level. The use of the FKBP12-FRB fusion protein combined with DSC and NMR provides a useful tool for the efficient screening of FKBP12-dependent as well as -independent inhibitors of the mTOR FRB domain.     

Synthetic caged DAG-lactones for photochemically controlled activation of protein kinase C

Switching on kinases: Synthetic caged DAG-lactones have been developed and showed decreases of two orders of magnitude, relative to the corresponding parent compounds, in their binding affinities towards PKC. The caged compounds had no effect on the translocation of PKC until after photoactivation. This approach is a potentially powerful tool for probing the PKC signaling cascade.