A 90° fair circular waveguide bend.

We propose a synthesis method to design a 90° bent fair circular waveguide TE01 mode transition based on the non-uniform rational B-spline technique. The transition by this method has advantages of small geometry, high transmission with wide band and high profile fairness. An example of design of such a transition is presented. The simulation shows that the transition exhibits a transmission as high as 99.3% at the central frequency 35 GHz and has a bandwidth of 16.7% when keeping the transmission over 95%. Furthermore, the profile is extremely fair, which meets the requirements to decrease the geometry errors between actual device and its design, to reduce the machining difficulty in the machining process. The hot test data indicate that good transmission of the TE01 mode is obtained.

[Study on inhibitive effect of extracts from Scindapsus aureus on alpha-glucosidase and its antioxidant activity].

OBJECTIVE: To study the inhibitive effect of extracts from Scindapsus aureus on alpha-glucosidase and its antioxidant activity. METHODS: The 70% ethanol extracts was extracted by petroleum, ethyl acetate and n-butanol, and the inhibitory activity against alpha-glucosidases and antioxidative effects of each fraction were determined in vitro, and the inhibitory kinetics of ethyl acetate fraction was investigated. RESULTS: The inhibitory activity of ethly acetate fraction against alpha-glucosidase was higher as its IC50 was 43.63 microg/mL. The inhibition kinetics analyzed by Hnewaver-Burk plots showed that ethyl acetate fraction was a competitive type inhibitor, and the inhibition constants for free ennzyme (Ki) was determined to be 21.49 microg/mL. The antioxidative effects of ethly acetate and n-butanol fractions exhibited stronger than that of other fractions, the scavenging ability on DPPH at the concentration of 0.42 mg/mL were 88.5% and 93.6%. Ethly acetate fraction showed scavenging ability on autioxidantor, and the IC50 values was 0.27 mg/mL. CONCLUSION: Ethyld acetate fraction of extract from Scindapsus aureus has potential inhibitroy activity against alpha-glucosidase and antioxidant effects, and n-butanol fraction has great antioxidative effects.

[Inhibition of extracts from Synotis erythropappa on tyrosinase].

OBJECTIVE: To study the inhibition of extracts from Synotis erythropappa on tyrosinase. METHODS: The 70% ethanol extracts were extracted by petroleum benzine, ethyl acetate and n-butanol, and the inhibitory activities against tyrosinase of every fraction were determined in vitro and the inhibitory kinetics of ethyl acetate and n-butanol fractions were investigated. RESULTS: The four fractions extracted all had inhibitory activities on tyrosinase, inhibitory activities of ethyl acetate and n-butanol fraction were higher. Their IC50 were 57.8, 140 microg/ml for monophenol oxidase activity and 41.2, 59.6 microg/ml for diphenol oxidase activity, respectively. The inhibition kinetics analyzed by Hnewaver-Burk plots showed that ethyl acetate fraction was a competitive type inhibitor, and its Ki was determined to be 19.7 microg/ml. n-butanol fraction was an uncompetitive type inhibitor, and its Ki was determined to be 60.7 microg/ml. CONCLUSION: Ethyl acetate and n-butanol fractions of extracts from Synotis erythropappa show potential inhibitory activity on tyrosinase.