新疆紫草细胞培养产生紫草宁衍生物的代谢调控

本文对新疆紫草培养细胞的生长及紫革宁衍生物形成的调节与控制进行了研究．结果表朗：在不同时期照射白光、蓝光，对紫草培养细胞生长及紫草宁衍生物的积累均有明显的抑制作用;而第三周照红光一天、第二周以及整个培养过程均照远红光、第19天照紫外光等，都对生产培养基中紫草宁衍生物的积累有促进作用;其中，远红光与紫外光的最佳照射时间长度都为30分钟，且细胞内苯丙氨酸解氨酶的活性与紫草宁衍生物的含量有明显的正相关性．研究了不同照光条件下，紫草培养细胞生长，紫草宁衍生物积累以及苯丙氨酸解氨酶活性变化的动态，基本上找出了它们的变化规律以及它们之间的相互关系． 通过试验发现，紫草细胞培养的适宜温度为25℃，适宜pH值为5.3—5.8：在培养基中加入O,l%-0.30%的活性炭、用磁水器处理培养基等，对紫草宁衍生物的积累有良好的促进作用。 提高培养基中的Cu2+，Mg2+，Zn2+．K+浓度，有利于紫草宁衍生物的积累，而在生产培养基中加入NH：，则显著抑制了紫草宁衍生物的产生;培养基中蔗糖浓度为50g／L时，对紫草细胞生长及紫草宁衍生物的积累最有利，而生产培养基中不加IAA，KT对紫草宁衍生物的积累有利．以密环菌为诱导子，促进了紫草细脆生长及紫草宁衍生物的积累。 此外，对Cu2+、密环菌发酵液处理条件下，紫革宁衍生物积累与苯丙氨 酸解氨酶活性的关系以及不同蔗糖浓度条件下，生长培养基中紫草细胞生长、 紫草宁衍生物的积累，细胞内可溶性糖含量变化的动态进行了研究．

SUB-BAND CODING TECHNIQUES FOR ROBUST 4. 8 TO 8 kb/s SPEECH CODERS.

This paper describes a speech coding technique that has been developed in order to provide a method of digitising speech at bit rates in the range 4. 8 to 8 kb/s, that is insensitive to the effects of acoustic background noise and bit errors on the digital link. The main aim has been to develop a coding scheme which provides speech quality and robustness against noise and errors that is similar to a 16000 b/s continuously variable slope delta (CVSD) coder, but which operates at half its data rate or less. A desirable aim was to keep the complexity of the coding scheme within the scope of what could reasonably be handled by current signal processing chips or by a single custom integrated circuit. Applications areas include mobile radio and small Satcomms terminals.

Synthesis and properties of a new series of low-molar-mass organo-siloxane derivatives

Two series of ferroelectric liquid crystalline organo-siloxanes containing a laterally attached halogen on the phenyl ring have been synthesised and characterised to determine the impact of the siloxane group and the halogen on the mesomorphism and electro-optic switching properties. Both monomesogenic and bimesogenic compounds have been studied. The monomesogenic derivatives were found to be ferroelectric with high tilt and Ps. The tilt angle of 45° and the Ps of 95nC/cm2 are almost temperature independent. The bimesogenic bromo substituted derivatives showed mainly ferroelectric phases about 60°C wide. Maximum values for the spontaneous polarisation and the tilt angle were only slightly influenced by the length of the siloxane spacer. Altering the halogen to a fluorine shifted the liquid cystalline phase slightly to higher temperatures whilst maintaining the mesophase range of 60°C.

Ferroelectric liquid crystal mixtures containing chiral ether and ester compounds with the 2-arylidene-p-menthan-3-one skeleton

Some 1R,4R-2-(4-phenylbenzylidene)-p-menthane-3-one derivatives containing the ether or ester linking group between benzene rings of the arylidene fragment have been studied as chiral dopants in ferroelectric liquid crystal systems based on the eutectic mixture (1:1) of two phenylbenzoate derivatives CmH2m+1OC6H4COOC6 H4OCnH2n+1 (n = 6; m = 8, 10). The ferroelectric properties of these compositions (spontaneous polarization, rotation viscosity, smectic tilt angle as well as quantitative characteristics of their concentration dependences) were compared with those for systems including chiral dopants containing no linking group. Ferroelectric parameters of the induced ferroelectric compositions studied have been shown to depend essentially on the presence of the linking group between benzene rings and its nature as well as on the number of the benzene rings in the rigid molecular core of the chiral dopants used. For all ferroelectric liquid crystal systems studied, the influence of the chiral dopants on the thermal stability of N*, SmA and SmC* mesophases has been quantified. The influence of the linking group nature in the dopant molecules on the characteristics of the systems studied is discussed taking into account results of the conformational analysis carried out by the semi-empirical AM1 and PM3 methods.