Stability of oxygen anions and hydrogen abstraction from methane on reduced SnO2 (110) surface

The stability of oxygen anions and the hydrogen abstraction from methane on a reduced SnO₂ (110) crystal surface have been studied theoretically using a point-charge model. The geometric and electronic structures for the present molecules are calculated by means of a hybrid Hartree–Fock/density functional method at the B3LYP/6-311+G(3df, 3pd) level of theory. The calculations of the energies on the point-charge model are performed using these optimized geometries. It is found that a low concentration of the active oxygen species O⁻ and O₂⁻ is expected on the reduced SnO₂ surface. The activation energies for the abstraction of hydrogen atom from methane on the reduced SnO₂ surface are obtained: 12 kcal/mol for O⁻ species and more than 48 kcal/mol for O₂⁻ species, indicating that O⁻ species on the surface is the main active center for the dissociation of a C(SINGLE BOND)H bond of methane, which is in agreement with the other oxide catalysts. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 669–678, 1998     

Thermal and ionic‐conductive behaviors of liquid crystalline polymers with alkali metal salt

In order to investigate the relationship between ionic conductivity and liquid crystallinity, we prepared the main‐chain type polyester having 1,4‐bisstyrylbenzene units and ethyleneoxide chain in the repeating unit. The main‐chain type polyester with lithium salt at the ratio of 0.04 per polymer repeating unit exhibited a smectic phase. However, the polyester with lithium salt (0.11) showed a nematic phase. The ionic conductivity of the polyester with lithium salt increased with increasing lithium salt concentration. The trans‐type polyester exhibited a liquid crystalline phase, while the cis‐type polyester did not show any mesophase. We found that the ionic conductivity of the trans‐type polyester with lithium salt (0.11) was larger than that of the cis‐type polyester with lithium salt (0.11). However, a liquid crystalline phase was found in the side‐chain type polyether with alkoxy chain length of below 12. A smectic phase was induced for the non‐mesomorphic polyethers with lithium salt. The layer spacing of the smectic A phase for the non‐mesomorphic polyether with lithium salt decreased from 55 to 41 Å with increasing temperature. The ionic conductivity of the polyether with lithium salt increased with decreasing the layer spacing. Copyright © 2001 John Wiley & Sons, Ltd.     

An intrinsic characterization of isometric pluriharmonic immersions with codimension one

We give an intrinsic characterization of isometric pluriharmonic immersions of Kähler manifolds into semi-Euclidean spaces with real codimension one, which is a generalization of the Ricci-Curbastro theorem.Research partly supported by the Grants-in-Aid for Encouragement of Young Scientists, The Ministry of Education, Science and Culture, Japan.     

Development of Rapid and Facile Solid-Phase Synthesis of PROTACs via a Variety of Binding Styles

Optimizing linker design is important for ensuring efficient degradation activity of proteolysis-targeting chimeras (PROTACs). Therefore, developing a straightforward synthetic approach that combines the protein-of-interest ligand (POI ligand) and the ligand for E3 ubiquitin ligase (E3 ligand) in various binding styles through a linker is essential for rapid PROTAC syntheses. Herein, a solid-phase approach for convenient PROTAC synthesis is presented. We designed azide intermediates with different linker lengths to which the E3 ligand, pomalidomide, is attached and performed facile PROTACs synthesis by forming triazole, amide, and urea bonds from the intermediates.     

Effect of soft segment component on moisture‐permeable polyurethane films

The effect of soft segment component and molecular weight combination on moisture‐permeable polyurethane films was studied. Moreover, water sorption phenomenon in films was observed with infrared analysis. As for soft segment components, PTMG/PEG and PTMG/PPG were used and molecular weight combinations were changed. Different tendency appeared in the experimental results corresponding to PEG system and PPG system. Moisture permeability P in PEG system increased with increasing PEG content, but P changed little in the case of PPG system. Both hydrogen‐bonded concentration by infrared measurement and the higher order term Δh of Mooney–Rivlin plot by stress–strain relationships indicate the existence of aggregate structure of hard segment. It is considered that ether group in PEG is more active than that in PPG. Therefore, small size of aggregate structure indicated as Δh appears in PEG system owing to inhibition of aggregate structure growth. Whereas, ether group in PPG system does not inhibit hydrogen bond in urethane group and large size of aggregate structure appears. From water affinity relationship analysis, hydrophilicity of samples with PTMG/PEG = 2000/2000 increased with increasing PEG content. Consequently, it is suggested that not only size but also hydrogen‐bonded concentration of urethane group in aggregate structure affects moisture permeability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 573–583, 2006     

Synthesis of hyperbranched poly(ether nitrile)s by one‐step polycondensation of an AB2 monomer

Hyperbranched poly(ether nitrile)s were prepared from a novel AB₂ type monomer, 2‐chloro‐4‐(3,5‐dihydroxyphenoxy)benzonitrile, via nucleophilic aromatic substitution. Soluble and low‐viscous hyperbranched polymers with molecular weights upto 233,600 (M_w) were isolated. According to the ¹H NMR and GPC data, the unique polymerization behavior was observed, which implies that the weight average molecular weight increased after the number average molecular weight reached plateau region. Model compounds were prepared to characterize the branching structure. Spectroscopic measurements of the model compounds and the resulting polymers, such as ¹H, DEPT ¹³C NMR, and MS, strongly suggest that the ether exchange reaction and cyclization are involved in the propagation reaction. The side reactions would affect the unique polymerization behavior. The resulting polymers showed a good solubility in organic solvents similar to other hyperbranched aromatic polymers. The hydroxy‐terminated polymer was even soluble in basic water. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5835–5844, 2009     

Synthesis of polyester having pendent hydroxyl groups via regioselective dehydration polycondensations of dicarboxylic acids and diols by low temperature polycondensation

In this article, we describe the one‐step synthesis of polyesters having pendent hydroxyl groups by Lewis acid‐catalyzed, regioselective, dehydration polycondensations of diols (glycerol and sorbitol) and dicarboxylic acids [tartaric acid (TA) and malic acid (MA)] containing pendent hydroxyl groups, using low temperature polycondensation technique. Direct polycondensations of TA or MA and 1,9‐nonanediol catalyzed by scandium trifluoromethanesulfonate [Sc(OTf)₃] successfully yielded linear polyesters having hydroxyl functionality (M_n = ca. 1.0 × 10⁴). To demonstrate the reactivity of the pendent hydroxyl group, a glycosidation was performed. Poly(nonamethylene L ‐malate) showed significant higher biodegradability, compared with poly(nonamethylene L ‐tartrate) or poly(nonamethylene succinate). Stable poly(nonamethylene L ‐tartrate) emulsion could be prepared using poly(vinyl alcohol) as the surfactant, although emulsions consisting of poly(nonamethylene succinate) were unstable and phase‐separated within a few days. Furthermore, direct polycondensations of TA and diethylene glycol (DEG) or triethylene glycol (TEG) successfully produced water‐soluble polyesters having hydroxyl groups. This new polycondensation system may be extremely effective not only for advanced material design using functional monomers but also for effective utilization of biomass resources as chemical substances. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5747–5759, 2009     

Phosphorimetric microassay for succinyltrialanyl-p-nitroanilide-hydrolyzing enzyme activity in human serum

A phosphorimetric assay of succinyltrialanyl-p-nitroanilide-hydrolyzing enzyme activity in human serum is described. p-Nitroaniline formed enzymatically is extracted with ether and determined phosphorimetrically in an ether/ethanol glass. The method is precise and very sensitive, requiring as little as 5 μl of human serum. The limit of detection is 10 pmol.     

Designable formation of metal nanoparticle array with the deposition of negatively charged nanoparticles

Ultrafine gold and platinum nanoparticles (NPs) were fabricated by pulsed laser ablation in helium gas and the NPs 2-15 nm in diameter were selectively classified by an electrostatic size-selection technique employing a low-pressure differential mobility analyzer (LP-DMA). The spherical NPs obtained showed a narrower distribution of diameters of anionic NPs over cationic NPs. With this knowledge, the anionic NPs were deposited onto silicon substrates designed by electron beam lithography processing, and designable patterns of arrayed NPs were produced by removing the photoresist layer.     

High-efficiency longitudinally-pumped miniature Nd:YVO4 laser

We report on fundamental and intracavity frequency-doubled emission in a miniature Nd:YVO₄ (3×3×1 mm) laser. A maximum slope efficiency of η_s=58.6%, with optical efficiency of η₀=53.0% at 780 mW pump power was realized in a TEM₀₀ output beam. To obtain the optimum pump-beam focusing conditions we applied a new formalism in which the pump-beam propagation in the active medium was described by its M² factor. A good agreement between theoretical predictions and experimental results was observed. In second-harmonic regime, obtained by a KTP crystal, 230 mW green power that corresponds to 54% nonlinear conversion efficiency was reached.