Method for Evaluating Potential Maximum Shear Strain for a Fine Metal Wire in Torsion Testing

Experimental Techniques - The torsion number of drawn fine high carbon steel wires was measured through torsion testing. The angles between the scratches on the tested wire surface and its...     

Culcitiolides A-D, four new eremophilane-type sesquiterpene derivatives from Senecio culcitioides

Four new eremophilane-type sesquiterpenes, culcitiolides A-D, were isolated from the stem of Senecio culcitioides Sch. Bip (Asteraceae). Their structures were established by detailed 2D NMR spectroscopic and single-crystal X-ray experiments. These compounds were assessed for inhibitory activity against nuclear factor kappaB (NF-kappaB). Culcitiolides C and D at 20 microM showed 97 and 100% inhibition of NF-kappaB activity, respectively.     

CIDEP in radical-singlet molecular oxygen system

Net absorptive CIDEP generation has been demonstrated on singlet molecular oxygen and 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxyl (OTEMPO) radical system in benzene. CIDEP generation was reasonably explained in terms of the radical-triplet pair mechanism of triplet molecular oxygen-OTEMPO pair with doublet precursor. Several excited molecule-OTEMPO systems have been investigated if this CIDEP generation contributes to their CIDEP spectra. Surprisingly strong CIDEP was produced even in the presence of trace amount of dissolved oxygen, which suggests the importance of complete degassing for CIDEP studies in general systems.     

Vibrationally assisted diffusion of H2O and D2O on Pd(1 1 1)

The adsorption and diffusion of isolated H₂O and D₂O molecules on Pd(1 1 1) were studied using scanning tunneling microscopy at low temperature (∼40 K). At low tunneling voltage the diffusion is thermally activated. The diffusion rate is enhanced by several orders of magnitude when the tunneling electron has enough energy to excite the vibrational “scissor” mode of the molecule. An isotope effect was observed in the threshold voltage for electron-assisted diffusion of H₂O and D₂O.     

Rooted tree analysis of the order conditions of row-type scheme for stochastic differential equations

Numerical schemes for initial value problems of stochastic differential equations (SDEs) are considered so as to derive the order conditions of ROW-type schemes in the weak sense. Rooted tree analysis, the well-known useful technique for the counterpart of the ordinary differential equation case, is extended to be applicable to the SDE case. In our analysis, the roots are bi-colored corresponding to the ordinary and stochastic differential terms, whereas the vertices have four kinds of label corresponding to the terms derived from the ROW-schemes. The analysis brings a transparent way for the weak order conditions of the scheme. An example is given for illustration.     

Synthesis and characterization of Ti(IV)-substituted calcium hydroxyapatite particles by forced hydrolysis of Ca(OH)2-Na5P3O10-TiCl4 mixed solution

Ti(IV)-substituted calcium hydroxyapatite (TiHap) particles were prepared by aging Ca(OH)₂, TiCl₄, and sodium triphosphate (sodium tripolyphosphate, Natpp: Na₅P₃O₁₀) mixed solution at 100 °C for 18 h. The ellipsoidal secondary TiHap particles with ca. 100～150 nm in length composing by aggregation of small ellipsoidal primary particles with ca. 20 nm in length were produced at atomic ratio of Ti/(Ca+Ti) [X_Ti]≦0.2. The in situ IR spectra of these TiHap particles exhibited very small bulk OH^? band at 3,570 cm^?1. This result indicated that the TiHap particles were formed by aggregation of fine primary particles and OH^? ions along with c-axis in the primary particles were disordered. The TiHap particles with Ca/P atomic ratio larger than theoretical value of 1.67 did not exhibit surface P–OH groups at 3,659 and 3,682 cm^?1. The diffuse reflectance UV spectra of TiHap particles revealed that these particles have a UV absorption property, especially fabricated at X_Ti?=?0.1. The particles prepared at X_Ti?=?0.6 and 0.8 were amorphous and nanoparticles with 5～10 nm in diameter, but those precipitated at X_Ti?=?1.0 were poorly crystallized anataze-type TiO₂ nanoparticles.     

Encapsulation with the Protrusion of Cruciform 9,10‐Bis(arylethynyl)anthracene Derivatives in a Self‐Assembled Boronic Ester Cavitand Capsule: Photochemical and Photophysical Properties

The self‐assembled boronic ester cavitand capsule 3 quantitatively and tightly encapsulates 2,6‐diacetoxy‐9,10‐bis(arylethynyl)anthracene derivatives 4 a – 4 c as highly fluorescent cruciform guests to form complexes 4 a @ 3 , 4 b @ 3 , and 4 c @( 3 )₂. The structural features of capsule 3 , which possesses two polar bowl‐shaped aromatic cavity ends and four large equatorial windows connected by dynamic boronic ester bonds, made it possible to encapsulate cruciform 4 with protection of the reactive anthracene core inside the capsule and with two protruding arylethynyl groups, the π‐conjugated arms of compound 4 , through two of the equatorial windows of the capsule. Thus, complexes 4 a @ 3 , 4 b @ 3 , and 4 c @( 3 )₂ show greater resistance to photochemical reactions in solution and fluorescence quenching in the powder state compared to free guests 4 . In addition to the improved photostability, restriction of the free rotation of the arylethynyl groups of guests 4 upon encapsulation results in sharpening of the UV/Vis absorption peaks with a red‐shift and a significant increase in some of the two‐photon‐absorption peaks of complexes 4 a @ 3 , 4 b @ 3 , and 4 c @( 3 )₂ compared with free guests 4 .     

The Influence of Defects on the Propagation Light within Polymeric Optical Waveguides Studied by Polarized Near-Field Scanning Optical Microscopy

We have developed a polarization-preserving near-field scanning optical microscopy (NSOM) optical fiber probe and with it observed the influence of defects and weak stresses on a propagation light within polymeric optical waveguides. To characterize the influence, we intentionally printed an indentation in the vicinity of the waveguide and then evaluated the resulting influence using polarized guide-collection-mode NSOM images taken around the indentation. When transverse magnetic polarized light enters a waveguide, the light intensity becomes greater on the near side of the indentation than on the far side, as measured by a linearly polarized component perpendicular to the direction of light propagation. The most probable cause of this phenomenon is microdefects generated by the printing of the indentation. The polarized NSOM technique is useful in searching for small defects or stresses within integrated photonic devices.     

Nuclear Resonant Inelastic and Forward Scattering of Synchrotron Radiation by 40K

We achieved excitation of the first excited state of ⁴⁰K and confirmed both energy and lifetime. Furthermore, we observed nuclear resonant inelastic scattering by ⁴⁰K in a powdered KCl sample at room temperature using a high-resolution monochromator. The time spectrum of the nuclear resonant forward scattering was measured at 50 K. Our observations of nuclear resonant inelastic and forward scattering by ⁴⁰K make electronic and dynamic studies for potassium practical. The measurements of nuclear resonant scattering for the radioactive ⁴⁰K nuclide will enable and lead to further studies of other radioactive nuclides. This revised version was published online in August 2006 with corrections to the Cover Date.