The development of a method for the Pd(ii)-catalyzed denitrogenative coupling of arylhydrazines to give functionalized biaryls in good yield, using aryl bromides or aryl iodides as convenient and inexpensive aryl sources, is reported. High functional group tolerance is demonstrated for electronically distinct arylhydrazines as well as aryl halides. The desired products were isolated in good to excellent yields for 58 examples. Control experiments and mechanism studies revealed that the transformation undergoes a base-promoted Pd-catalyzed process.

Plain concrete is susceptible to cracking under aggressive environment such as in freezing shaft. And addition of steel fibres in plain high strength concrete is proved to be effective in cracking resistance and brittleness improvement, etc. This paper presents results of experimental investigation carried out to study the mechanical properties of steel fibre-reinforced concrete having volume fractions of 0.38%, 0.51% and 0.64% for two types of fibres respectively. The results of this study revealed that there is an increase for all the mechanical properties such as compressive strength, split tensile strength, modulus of elasticity and flexural strength. Enhancement for split tensile strength and flexural strength is more evident than compressive strength.

According to the special construction environment and curing conditions of the freezing shaft inner and outer shaft lining in deep alluvium, first,configuration principle of high strength high performance concrete of freezing shaft in deep alluvium is proposed; Then raw materials are selected according to the preparation approach, and preparation experimental study of high strength high performance concrete is conducted with C60, C65, C70and C75 , and the optimum mixture ratio is obtained, and applied to the engineering practice, achieving remarkable effect.

For the economic and reasonable application of high strength composite shaft lining of steel and concrete, the mechanical characteristic of this kind of structure were studied. First of all, according to the similarity theory, the shaft lining model is designed, then making the specimen and the loading test are put into effect. The results show that the combined action of inner and outer steel tube and middle concrete improves their respective performance. In shaft lining structure the stability of steel tube would be enhanced and the brittleness of high strength concrete would be improved also, so shaft lining structure shows fairly plastic feature when it is destroyed. Moreover, because of the restraint function of double-layer plate, the concrete in shaft lining structure completely is in triaxial compression stress state, the compressive strength can improve 1.53 ~ 1.90 times more than the concrete under uniaxial compression. The bearing capacity of shaft lining also increased greatly. Therefore, it is proposed that the improvement coefficient of the concrete’s compressive strength should be considered in the strength calculation of high composite shaft lining structure of steel and concrete.