A New Synthesis of Benzofurans from Phenols via Claisen Rearrangement and Ring‐Closing Metathesis

Based on Claisen rearrangement, the double bond isomerization of O‐allyl function together with the formation of O‐vinyl function in one pot, and ring‐closing metathesis (RCM), various phenols were transformed into various benzofurans in good yields.     

Long-Period Gratings in Planar Optical Waveguides

Our progress in the study of long-period gratings (LPGs) in planar optical waveguides is reviewed. In particular,experimental LPGs in glass and polymer waveguides are presented to demonstrate the potential of LPG-based waveguide devices.     

关于3连通图的容错直径和宽直径

容错直径和宽直径是度量网络可靠性和有效性的重要参数．对任意k连通图，它的容错直径Dk不超过宽直径dk,本证明：当D2=2时，d3≤max{D， l，2D3-2}；当D2≥3时，d3≤(D2-1)[2(D2-1)(D3-1)-D2-2] 1．     

Design and analysis of coplanar waveguide optical modulator using finite element method

An analysis is given on the finite element method (FEM) for calculating the various parameters of optical modulators and a computer program is written to solve the finite element equation. Based on this method, a Mach-Zehnder type electro-optic modulator with coplanar waveguide (CPW) electrode is designed and fabricated. When compared with the Fourier series method, small differences on the 3-dB bandwidth, characteristic impedance and half-wave voltage, etc. are obtained.     

An ion-selective electrode for methylamine

A simple electrode is described for the assay of methylamine in the concentration range 10^-5–10^-2 M. The electrode is based on the air-gap sensor principle. In the range of linear response, the relative standard deviation is about 1.4 % when the measurement time is 24 min, and about 5 % when the equilibration time is 12 min. Some interference is noted from dimethylamine and ammonium chloride.     

Structural properties of inner amenable groups

For infinite discrete groups, Effros introduced the notion of inner amenability which gives a new classification of discrete groups. The inner amenability is a considerably weaker condition than amenability, but closely related to the quite deep property Γ of groups. In this paper the author investigates the structures of inner amenable groups by theoretical set theory. A sequence of characterizations of inner amenable groups is given here by developing the well-known Folner's conditions for amenable locally compact groups. This work is partly supported by the National Science Foundation of China.     

An artificial intelligence system for computer-aided mass spectra interpretation of saturated aliphatic monohydric alcohols

The mass spectra of saturated monohydric alcohols are used in structure elucidation by means of computer programs of the artificial intelligence type. The structure generator is constrained by a structure predictor to show the sub-group structure in a fairly definite area, and spectral characteristics are also predicted. According to the commands of the structure predictor, sub-groups conforming to the mass spectra studied are then combined into molecular structures which are ranked for output. The system was tested for 218 mass spectra of 115 alcohols from different laboratories: all the correct answers were included in the 6 highest scores, with 78% for the highest score and 91% for the highest 2 scores.     

Mg-Benzophenonketyl als Initiator für die anionische Polymerisation von Methylmethacrylat

Ohne Zusammenfassung     

A specific enzyme electrode for L-phenylalanine

A specific enzyme electrode procedure is described for the rapid assay of L-phenyl- alanine. The enzyme L-phenylalanine ammonia lyase is used, which cleaves L-phenyl-alanine to ammonia. The ammonia liberated is measured with an air-gap electrode. The procedure is specific; L-tyrosine and other amino acids do not interfere, nor do Na⁺ or K⁺ ions. As little as 5 · 10^-5 M L-phenylalanine can be determined.