Crystal structures and magnetic properties of fluorite-related oxides Ln3NbO7 (Ln=lanthanides)

Crystal structures and magnetic properties of the ternary oxides Ln₃NbO₇ (Ln=La, Pr, Nd, Sm-Lu) are reported. Their powder X-ray diffraction measurements and Rietveld analyzes show that they have the fluorite-related structures with space group Pnma (Ln=La, Pr, Nd), C222₁ (Ln=Sm-Tb), or Fm-3m (Ln=Dy-Lu). Magnetic susceptibility measurements were carried out from 1.8 to 400 K. The Ln₃NbO₇ compounds for Ln=Pr, Gd, Dy-Yb show Curie-Weiss paramagnetic behavior, and Sm₃NbO₇ and Eu₃NbO₇ show van Vleck paramagnetism. On the other hand, two magnetic anomalies were observed for both Nd₃NbO₇ (0.6 and 2.7 K) and Tb₃NbO₇ (2.0 and 3.2 K). From the results of specific heat measurements, it was found that these anomalies are due to the antiferromagnetic ordering of Ln ions in two different crystallographic sites (the 8-coordinated and 7-coordinated sites).     

Isothermal phase equilibria and structural phase transition in the carbon dioxide + cyclopropane mixed-gas hydrate system

The isothermal phase equilibria of the carbon dioxide + cyclopropane mixed-gas hydrate system were investigated by means of static temperature measurement and Raman spectroscopic analysis. Raman spectra indicated that the crystal structure of the carbon dioxide + cyclopropane mixed-gas hydrate changes from structure-I to structure-II and back to structure-I with an increase of the equilibrium carbon dioxide composition at 279.15 K, while each simple gas hydrate belongs to structure-I at the temperature. Whereas, unlike 279.15 K, no structural phase transition occurs along the isothermal stability boundary at 284.15 K.     

Stability of travelling wave solutions to a semilinear hyperbolic system with relaxation

We study a semilinear hyperbolic system with relaxation and investigate the asymptotic stability of travelling wave solutions with shock profile. It is shown that the travelling wave solution is asymptotically stable, provided the initial disturbance is suitably small. Moreover, we show that the time convergence rate is polynomially (resp. exponentially) fast as t→∞ if the initial disturbance decays polynomially (resp. exponentially) for x→∞. Our proofs are based on the space–time weighted energy method. Copyright © 2008 John Wiley & Sons, Ltd.     

3-dynamic coloring of planar triangulations

An $r$-dynamic $k$-coloring of a graph $G$ is a proper $k$-coloring such that any vertex $v$ has at least $min\{r,{deg}_G\left(v\right)\}$ distinct colors in $N_G\left(v\right)$. The $r$-dynamic chromatic number${\chi }_r^d\left(G\right)$ of a graph $G$ is the least $k$ such that there exists an $r$-dynamic $k$-coloring of $G$.Loeb et al. (2018) showed that if $G$ is a planar graph, then ${\chi }_3^d\left(G\right)\le 10$, and there is a planar graph $G$ with ${\chi }_3^d\left(G\right)=7$. Thus, finding an optimal upper bound on ${\chi }_3^d\left(G\right)$ for a planar graph $G$ is a natural interesting problem. In this paper, we show that ${\chi }_3^d\left(G\right)\le 5$ if $G$ is a planar triangulation. The upper bound is sharp.     

Optimal decay estimates of a regularity-loss type system with constraint condition

In the paper [14], the authors formulated a new structural condition which includes the Kawashima–Shizuta condition, and analyzed the weak dissipative structure called the regularity-loss type for general systems which contain the Timoshenko system and the Euler–Maxwell system. However, this new structural condition can not cover all of dissipative systems. Indeed we introduce a dissipative system which does not satisfy the new condition and analyze the weaker dissipative structure in this paper. Precisely we first derive the $L^2$ decay estimate of solutions and discuss the type of the corresponding regularity-loss structure. Moreover, in order to show the optimality of the decay estimate, we analyze the expansion for the corresponding eigenvalue of our problem and derive that the solution approaches the diffusion wave as time tends to infinity.     

ChemInform Abstract: Crystal Structures and Magnetic Properties of Fluorite‐Related Oxides Ln3NbO7 (Ln = Lanthanides).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Identification of Glycyrrhiza species by direct analysis in real time mass spectrometry

DART (Direct Analysis in Real Time)-MS is a novel mass spectrometric ion source, and allows the analysis of most compounds at ambient pressure and ground potential by producing [M+H]+ molecular ion species. Using this method, we examined the compounds characteristic of several kinds of licorices. For the analysis of Glycyrrhiza inflata Batalin, the peak at m/z 339 originates mainly from [M+H]+ of licochalcone A (LA), a species-specific compound. This peak was hardly detected in G. glabra Linné and G. uralensis Fischer. These results indicate that G. inflata can be differentiated from the other two species by detection of LA peaks using DART-MS analysis.     

Solvent-induced morphological diversification in poly(l-lactide-b-?-caprolactone) block copolymer thin films

Biodegradable block copolymer of poly(l-lactide-b-?-caprolactone) (P(LA-b-CL)) was dissolved in various solvents with different solubility as well as volatility, and spin-cast on a highly oriented pyrolytic graphite (HOPG) to prepare thin films. The surface morphologies were observed by using atomic force microscopy (AFM) in a dynamic force (tapping) mode. Particle like morphology was found in the thin films prepared form the dichloromethane and acetone. Higher volatility of dichloromethane and acetone resulted in the reflection of the particle like objects in the solution to HOPG substrate. In contrast, the P(LA-b-CL)s in toluene and 1,4-dioxane exhibited different morphologies compared to those in dichloromethane and acetone. Lower volatility of toluene and 1,4-dioxane assisted the epitaxial crystallization of PCL component along the HOPG lattice, that was revealed by enzymatic degradation of PLLA component by proteinase K. Thus, adjusting the solubility and solvent volatility for the film formation provided morphological divergence of the P(LA-b-CL) block copolymer, and this technique would be applicable for the surface patterning of biodegradable polymers.     

Structure and photoelectrochemical properties of phthalocyanine and perylene diimide composite clusters deposited electrophoretically on nanostructured SnO2 electrodes

Clusters of phthalocyanine and phthalocyanine-perylene diimide have been prepared and electrophoretically deposited on nanostructured SnO2 electrodes. The structure and photoelectrochemical properties of the clusters have been investigated by using UV-visible absorption, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM), and photoelectrochemical and photodynamical measurements. Enhancement of the photocurrent generation efficiency in the composite system has been achieved relative to that in the phthalocyanine reference system without the perylene diimide. Such information will be valuable for the design of molecular photoelectrochemical devices that exhibit efficient photocurrent generation.