A variational principle for doubly nonlinear evolution

The weighted energy-dissipation principle stands as a novel variational tool for the study of dissipative evolution and has already been applied to rate-independent systems and gradient flows. We provide here an example of its application to a specific yet critical doubly nonlinear equation featuring a super-quadratic dissipation.     

A practical synthesis of L-ribose

L-Ribose was synthesized by a simple four-step method with overall yield of 76.3% from a protected L-arabinose derivative, which is a compatible intermediate for the synthesis of L-deoxyribose. The key step of this strategy is the Swern oxidation and subsequent stereoselective reduction accompanied by inversion of the 2-hydroxy group of protected L-arabinose.     

Fullerene sensors based on calix[5]arene

A new class of fullerene sensors based on calix[5]arenes has produced the highly sensitive detection of C60 and C70.     

Metal-induced regulation of fullerene complexation with double-calix[5]arene

The metal-induced regulation of fullerene complexation with double-calix[5]arene is described. The receptor shows strong binding to C70 only in the presence of Cu+.     

Chamaechromone,a novel rearranged biflavonoid from Stellera chamaejasme L.

A novel biflavonoid, chamaechromone was isolated from $\text{Stellera chamaejasme}$ L. (Thymelaeaceae) and its structure elucidated by spectroscopic and chemical methods.     

[3]Parycyclo− and [3]metacyclo[3](3,7)-p-tropoquinonophanes

The title phanes were synthesized. Examination of their physical properties including X-ray crystallography disclosed that 1) the p-tropoquinone ring is still bent in both compounds though to a lesser extent than in the corresponding [2.2]phanes, 2) the metacyclo compound prefers syn conformation in solution, and 3) the intramolecular CT interaction is very similar in two compounds.     

Structures of xantholides A and B,two new guaianolides from xanthium canadense mill.

The structures of xantholides A and B were deduced on the basis of IR and NMR spectra, and confirmed by X-ray analysis. Xantholide A inhibited the larval growth of Drosophila melanogaster.     

Mössbauer study of the fraction of non-bridging oxygens in potassium borate glasses

A Mössbauer study was performed to find the fraction of non-bridging oxygens in potassium borate glasses containing a small amount of iron. The borate glasses with alkali contents of 15, 20, 25, 30 and 40 mol% were irradiated with ⁶⁰Co-γ rays at room temperature in a nitrogen atmosphere. The Mössbauer absorption area for the irradiation-induced Fe²⁺ increased with the total γ-ray dose in the range of 1 × 10⁶ ?2 × 10⁸ R, and became constant after irradiation ranging from 2 × 10⁸ R ? 1 × 10⁹ R. The absorption area for the Fe²⁺ at the saturated region was correlated with the difference in the glass structure, i.e., the fraction of the non-bridging oxygens was estimated from the increased absorption area for the Fe²⁺ as a function of the alkali content of the glasses. The fraction of the non-bridging oxygen increased with the alkali content of the glasses in the alkali region above 20 mol%, and about 14% of the fraction was obtained for an alkali content of 40 mol%.