Measurement of flow-birefringence using a circularly polarized laser beam

A method of measuring flow-birefringence is reported. In this method, a circularly polarized light wave is transmitted through the flow-birefringent medium. The transmitted elliptically polarized wave is compensated by a Babinet-Soleil plate to convert it back into a circularly polarized wave. The state of circular polarization is confirmed using the rotating-analyser method. Measurements can be carried out with a sample having a fixed azimuth. The minimum detectable optical retardation angle was 5 × 10^-3 degree. This corresponds to a birefringence of Δn = 1 × 10^-10, when the optical path length of the sample cell is 100 mm.     

Study of traditional Chinese animal drugs using FT-IR and 2D-IR correlation spectroscopy

Using FT-IR and 2D-IR correlation spectroscopy, the intensity changes and their sequence of amide I and II bands of four traditional Chinese animal drugs (Cornu Cervi Pantotrichum, Cornu Saigae Tataricae, Scorpio and Hirud) under thermal perturbation are studied, and component of Ca(3)(PO(4))(2) in the drug of Cornu Cervi Pantotrichum and sulfates components in the drug of scorpion are identified. The drug of Cornu Cervi Pantotrichum contains inorganic salt Ca(3)(PO(4))(2) and the drug of Scorpio contains sulfates. It is assigned that the bands of 604 and 561 cm(-1) belong to the component of Ca(3)(PO(4))(2), and the bands of 637 and 615 cm(-1) belong to sulfates. Organic components of these drugs respond to the thermal perturbation far stronger than that of the inorganic components. The intensities of amide I and II bands in the drugs, except for amide II band in drug Scorpio, change strongly. For the drugs of Cornu Cervi Pantotrichum, Cornu Saigae Tataricae and Hirudo, the intensity changes of amide II band occurs prior to that of amide I band. The C-N bond in the product operator(3)(4) conjugative system converts from double bond to single bond, but the C=O bond remains double bond during the heating process. On the other hand, amide II vibrations, which may involve much more of the hydrogen bonded local structures of amide groups in the system compared to the C=O dominated amide I vibration, may undergo thermally induced changes at a temperature much lower than the other mode. The traditional Chinese animal drugs can be identified rapidly and non-separately by using FT-IR and 2D-IR correlation spectroscopy.     

SINGLE AND DOUBLE EDGE INTERFACE CRACK SOLUTIONS FOR ARBITRARY FORMS OF MATERIAL COMBINATION

In this paper interfacial edge crack problems are considered by the application of the finite element method. The stress intensity factors are accurately determined from the ratio of crack-tip-stress value between the target given unknown and reference problems. The reference problem is chosen to produce the singular stress fields proportional to those of the given unknown problem. Here the original proportional method is improved through utilizing very refined meshes and post-processing technique of linear extrapolation. The results for a double-edge interface crack in a bonded strip are newly obtained and compared with those of a single-edge interface crack for different forms of combination of material. It is found that the stress intensity factors should be compared in the three different zones of relative crack lengths. Different from the case of a cracked homogeneous strip, the results for the double edge interface cracks are found to possibly be bigger than those for a single edge interface crack under the same relative crack length.     

Variation of the stress intensity factor along the front of a 3-D rectangular crack subjected to mixed-mode load

Summary  The singular integral equation method is applied to the calculation of the stress intensity factor at the front of a rectangular crack subjected to mixed-mode load. The stress field induced by a body force doublet is used as a fundamental solution. The problem is formulated as a system of integral equations with r ⁻³-singularities. In solving the integral equations, unknown functions of body-force densities are approximated by the product of polynomial and fundamental densities. The fundamental densities are chosen to express two-dimensional cracks in an infinite body for the limiting cases of the aspect ratio of the rectangle. The present method yields rapidly converging numerical results and satisfies boundary conditions all over the crack boundary. A smooth distribution of the stress intensity factor along the crack front is presented for various crack shapes and different Poisson's ratio. Received 5 March 2002; accepted for publication 2 July 2002     

A novel method for the terpene synthesis by the ring-opening reaction of β-methyl-β-propiolactone

A new route for the terpene synthesis is investigated, which undergoes via terpene carboxylic acids as key intermediates obtained by the regiospecific ring opening of β-methyl-β-propiolactone with a cuprate or with a Grignard reagent in the presence of a copper catalyst.     

An M2L4 Molecular Capsule with a Redox Switchable Polyradical Shell

Preparation of molecular nanostructures with polyradical frameworks remains a significant challenge because of the limited synthetic accessibility which is entirely different from that of neutral and ionic ones. Herein we report the quantitative formation of a new M₂L₄ molecular capsule from metal ions and dihydrophenazine‐based ligands. The capsule has a spherical nanocavity (ca. 1 nm in diameter) enclosed by eight redox‐active, dihydrophenazine panels. Electrochemical oxidation of the capsule leads to the generation of multiple radical cations on the shell framework. Moreover, a stable tetra(radical cation) capsule can be reversibly obtained by chemical as well as electrochemical oxidation.