<Emphasis Type="Italic">In Situ</Emphasis> Synthesis of Field-responsive Nanocrystalline BaTiO<Subscript>3</Subscript> Particles Modified with Functional Organics

Nanocrystalline BaTiO₃ particles modified with polarizable ligands were synthesized through hydrolysis of modified metal–organics below 100°C. BaTiO₃ precursor was synthesized from barium metal, titanium isopropoxide and polarizable ligands in a mixture of ethanol and 2-ethoxyethanol. The modified Ba–Ti complex alkoxide was hydrolyzed yielding BaTiO₃ particles modified with organics. The crystallinty of nanometer-sized particles was dependent upon the hydrolysis conditions, and increased with increasing water amount and time. The nanocrystalline particles were identified to be BaTiO₃ by X-ray diffraction (XRD) and electron diffraction. A fluid consisting of modified BaTiO₃ particles and silicone oil revealed a typical electrorheological (ER) behavior on applying DC field. The ER behavior was found to depend upon the kind of ligand. 4-Fluorobenzyloxy modifier revealed the highest yield stress in the ER measurement among 4-substitued benzyloxy ligands examined.     

Animation of fiber fuse damage, demonstrating periodic void formation

A series of optical micrographs showing the front region of fiber fuse damage were obtained to reveal the periodic void formation process. They were collected from a number of samples and were sorted in order of increasing distance between the top of the first large void and the top of the first regular void. The micrographs clearly show that the first large void sheds its tail, which shrinks to form a regular void. This mechanism leads to the formation of bullet-shaped regular voids as the result of the balance between the internal pressure of the optical discharge and the increasing viscosity of the surrounding glass that occurs during pinching off.     

Eigenvalue asymptotics for the Schrödinger operators on the hyperbolic plane

In this paper we consider the Schrödinger operator on the hyperbolic plane , where is the hyperbolic Laplacian and V is a scalar potential on . It is proven that, under an appropriate condition on V at ‘infinity’, the number of eigenvalues of H_V less than λ is asymptotically equal to the canonical volume of the quasi-classically allowed region as λ→∞. Our proof is based on the probabilistic methods and the standard Tauberian argument as in the proof of Theorem 10.5 in Simon (Functional Integration and Quantum Physics, Academic Press, New York, 1979).     

Ni-catalyzed, ZnCl(2)-assisted domino coupling of enones, alkynes, and alkenes

A Ni(0)/ZnCl(2) system effectively promotes the coupling of enones and alkene-tethered alkynes. In the reaction with 1,6-enynes, the oxidative cyclization of Ni(0) species on enones across the alkyne part followed by ZnCl(2)-promoted cleavage generates alkenylnickel intermediates. Subsequent migratory insertion of the tethered alkene occurs with 5-exo-cyclization. When the resulting sigma-alkylnickel intermediates have beta-hydrogen atoms, the reaction terminates by beta-hydrogen elimination to provide cyclopentane derivatives. On the other hand, a sigma-alkylnickel intermediate that does not have beta-hydrogen atoms undergoes the insertion of a second alkene unit to cause a domino effect via a three-fold C-C bond formation process with and without the cleavage of one C-C bond.     

Crystalline inclusion compounds constructed through self-assembly of isonicotinic acid and thiocyanato coordination bridges

The synthesis, crystal structures, inclusion ability, and structural robustness of novel crystalline inclusion compounds of [Ni(SCN)2(isoH)2].xG (isoH = isonicotinic acid; G = aromatic guest) are described. The inclusion compounds are constructed by stacking identical 2D host layers that consist of SCN-, isoH, and Ni2+ with van der Waals contact separation. In the layer, two types of rectangular cavities (A-type and B-type) are formed, and the guests are included in the former cavity. The inclusion compounds were categorized into four stacking modes according to the difference in the stacking mode of the layers. A systematic investigation of the crystal structures of the 21 inclusion compounds clarified the close relationship between the molecular structure of the guest and the resultant stacking mode of the layers.     

Adsorption and structure of methyl mercaptoacetate on Cu(1 1 1) surface by XPS and NEXAFS spectroscopy

Methyl mercaptoacetate (MA) on Cu(1 1 1) surface was investigated using synchrotron radiation-based X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. MA adsorbs on the surface via thiolate formation and weak interaction of the carbonyl group with the surface. Two different adsorption states previously reported for methanethiolate and ethanethiolate were confirmed, besides atomic sulfur. NEXAFS measurements support gauche-type conformation of MA whose skeleton lies on the surface.     

Pd/CZ三效催化剂中钯的团聚现象研究

通过浸渍法制备了一系列负载0.5%（重量百分比）Pd的氧化铈-氧化锆（NDK-84,由日本新日本电工株式会社提供）催化剂材料,并通过全面的表征手段,包括扫描电子显微镜（SEM）、透射电子显微镜（TEM）、高分辨透射电子显微镜（HR-TEM）、元素分布、X-射线衍射（XRD）,氮气吸脱附测试与比表面积和孔径分布分析（BET）、X射线光电子能谱（XPS）等,研究了不同Pd前驱体和不同热老化处理条件、H₂还原条件对Pd在铈锆固溶体上的分散、生长与烧结行为的影响,并评估了它们的三效催化活性.结果表明,热老化处理过程与还原过程显著影响了Pd在氧化物载体表面上的分散,因此导致不同的催化活性.     

Harmonicity of totally geodesic maps into nonpositively curved metric spaces

We prove the harmonicity of totally geodesic maps from a Riemannian manifold to a nonpositively curved metric space in the sense of Alexandrov for both Korevaar-Schoen-type and Cheeger-type energies. This enables us to make many examples of harmonic maps of an unknown type. We also construct an example of totally geodesic map between CAT(0)-spaces which is not harmonic.Mathematics Subject Classification (2000): 53C22, 53C43, 58E20     

Molar enthalpies of transfer of divalent transition metal lons and their chloro complexes from N,N-dimethylformamide to N,N-dimethylacetamide

The molar enthalpies of transfer _t H ^° of some divalent metal ions (M-Mn, Co, Ni and Zn) and their chloro complexes from N,N-dimethyl-for-mamide (DMF) to N,N-dimethylacetamide (DMA) have been determined using the tetraphenylarsonium-tetraphenylborate (TATB) assumption at 25°C. Although physicochemical properties of DMF and DMA as solvent are similar, the _t H ^°(M ²⁺) value increased significantly in the order Mnt H ^° values for the mono-and dichloro complexes showed also a strong metal dependence, while those for the triand tetrachloro complexes practically do not. These results can be reasonably explained in terms of steric hindrance upon solvation of the metal ions and complexes in DMA.