Structure comparison between Th2Zn17-type and TbCu7-type Sm–Fe intermetallic compounds and their nitrides by means of 57Fe-Mössbauer spectroscopy

Samarium–iron intermetallic compounds were prepared by a melt spinning method with low and high wheel speeds, which resulted in a Th₂Zn₁₇-type and a TbCu₇-type structure, respectively. Structure comparison between these types was investigated for Sm–Fe intermetallic compounds and their nitrides by ⁵⁷Fe-Mössbauer spectroscopy.     

A new tomato pregnane glycoside from the overripe fruits

A new pregnane glycoside has been isolated from the overripe fruits of Cherry tomato (Mini tomato), Lycopersicon esculentum var. cerasiforme (DUNAL) ALEF. The structure was determined to be 3-O-beta-lycotetraosyl 3beta-hydroxy-5alpha-pregn-16-en-20-one on the basis of spectroscopic analysis. The seasonal variation of the tomato saponin is discussed.     

A self-consistent cluster theory of amorphous materials

A cluster method for the electronic structure of amorphous materials is presented with an application to amorphous diamond. Eight-atom cluster model gives a pseudogap in the density of states.     

Letter: correlation between phosphorylation ratios by matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis and enzyme kinetics

To identify the correlation between the phosphorylation ratios by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-ToF MS) analysis and enzyme kinetics (K(m), V(max), and V(max)/K(m)) is important to understand whether MALDI-TOF MS can be applied for monitoring the properties of peptides that are substrates of protein kinases. The correlation between phosphorylation ratios and enzyme kinetics was examined using peptides for protein kinase C (PKC) and for 60 kDa phosphoprotein, encoded by the cellular sarcoma gene (c-Src). Phosphorylation ratios, analyzed by MALDI-ToF MS, showed higher correlation coefficient (r = > +0.7) for V(max)/K(m) compared with that (r = < -/+0.6) for K(m) or V(max). For ion modes, a higher correlation coefficient between phosphorylation ratios and V(max)/K(m) was identified in the positive mode (r = > +0.7) compared to that in the negative mode (r = < +0.5). These results suggest that MALDI-ToF MS is a useful tool to evaluate V(max)/K(m) of peptides for protein kinases.     

Defect-Free Synthesis of a Fully π-Conjugated Helical Ladder Polymer and Resolution into a Pair of Enantiomeric Helical Ladders**

Fully π-conjugated ladder polymers with a spiral geometry represent a new class of helical polymers with great potential for organic nanodevices, but there is no precedent for an optically active helical ladder polymer totally composed of achiral units. We now report the defect-free synthesis and resolution of a fully π-conjugated helical ladder polymer with a rigid helical cavity, which has been achieved by quantitative and chemoselective acid-promoted alkyne benzannulations of a rationally designed, random-coil achiral polymer followed by chromatographic enantioseparation. Because of a sufficiently high helix-inversion barrier, the isolated excess one-handed helical ladder polymer with a degree of polymerization of more than 15 showed a strong circular dichroism with a dissymmetry factor of up to 1.7×10⁻² and is thermally stable, maintaining its optical activity in solution even at 100 °C, as well-supported by molecular dynamics simulation.     

Highly selective sorption of small unsaturated hydrocarbons by nonporous flexible framework with silver ion

Ag2[Cr3O(OOCC2H5)6(H2O)3]2[alpha-SiW12O40] [1] is a nonporous flexible ionic crystal composed of 2D-layers of polyoxometalates ([alpha-SiW12O40](4-)) and macrocations ([Cr3O(OOCC2H5)6(H2O)3](+)) stacking along the b-axis. The silver ions are located in the vicinity of the oxygen atoms of the polyoxometalates. The sorption amounts of small unsaturated hydrocarbons such as ethylene, propylene, n-butene, acetylene, and methyl acetylene into 1 are comparable to or larger than 1.0 mol mol(-1) and large hystereses are observed, while those of paraffins and larger unsaturated hydrocarbons are smaller than the adsorption on the external surface (<0.2 mol mol(-1)). Fine crystals of 1 exhibit ethylene/ethane and propylene/propane sorption ratios over 100 at 298 K and 100 kPa, and the values are larger by 1 order of magnitude among those reported. The results of sorption kinetics, in situ IR spectroscopy, single crystal X-ray crystallography, and in situ powder XRD studies show that small unsaturated hydrocarbons penetrate into the solid bulk of 1 through the pi-complexation with Ag(+). The sorption property of 1 is successfully applied to the collection of ethylene from the gas mixture of ethane and ethylene.     

Design of polymeric carriers for cancer-specific gene targeting: utilization of abnormal protein kinase Calpha activation in cancer cells

We succeeded in cancer cell specific gene expression by using a polyplex responsive to protein kinase Calpha, which is activated in various types of cancer cells.     

The pH dependent nuclearity variation of {Mo(154-x)}-type polyoxomolybdates and tectonic effect on their aggregations

The pH dependence of the structures of {Mo(154-x)} mixed-valence oxomolybdate giant clusters were investigated by synchrotron X-ray diffraction of systematically prepared crystals containing [Mo138O410(OH)20(OH2)46](40-) (1), [Mo138O410(OH)20(OH2)38](40-) (2), [Mo138O406(OH)16(OH2)46](28-) (3), [Mo142O400(OH)52(OH2)38](28-) (4), [Mo142O432(OH2)58](40-) (5), [Mo148O436(OH)15(OH2)56](27-) (6), [Mo150O451(OH)5(OH2)61](35-) (7), and both [Mo150O442.5(OH)11.5(OH2)64](24.5-) and [Mo152O446(OH)20(OH2)54](28-) (8). Crystals 1, 4, and 5 contain discrete clusters while intercluster Mo-O-Mo bonds connect the clusters into chains in crystal 7, into two-dimensional networks in crystals 2 and 3, and into a three-dimensional framework structure in crystal 6. Crystal 8 contains both discrete and linearly catenated clusters: discrete {Mo150} are located between the chains of {Mo152}. Direct correlation was observed between the nuclearity of the clusters with the pH of the mother liquor. On the other hand, the geometries of extended structures do not show apparent correlation with the pH. They turned out to be governed by the tectonics of the component clusters. The pH of the mother liquor exerts influence on the extended structure through the structures of the constituent clusters.