Vinylic Substitution of Chlorine in the Reaction of 2,3,5,6-Tetrachloro-1,4-Benzoquinone with Cyclohexylamine in Acetonitrile Solvent

The reaction of 2,3,5,6-tetrachloro-1,4-benzoquinone with cyclohexylamine in acetonitrile has been studied spectrophotometrically. The mechanism of the reaction is a concerted vinylic substitution of Cl atoms. Kinetics and activation parameters are reported. This revised version was published online in June 2006 with corrections to the Cover Date.     

Experimental investigation on using the piezoelectric and electromagnetic vibration absorbers in milling

The paper presents an active control system that counteracts the development of chatter vibration. The vibration amplitude depends on the dynamic properties of the machine tool, cutting tool and work-piece. In the paper we analyze the case when the loss of machining stability is caused by the work-piece. The proposed active control system employs electromagnet or piezoelectric actuator to suppress vibration during milling. The active control introduces damping into the system, thereby raising the critical depth of cut and reducing forced vibration amplitude. It enables stable cutting under a much wider range of cutting parameters that for the uncontrolled system. Cutting tests are performed on JAFO FYN-50 machine with mill DIN 845 B-25 K-N HSS to demonstrate an effectiveness of the proposed systems.     

ChemInform Abstract: Growth and Characterization of Acentric BaHf(BO3)2 and BaZr(BO3)2.

Single crystals of BaHf(BO₃)₂ are grown on a Pt wire from BaHfO₃ (3.5 mol%) solved in a BaB₄O₇ melt (1050 °C soaking temperature, 1000-940 °C crystallization temperature gradient).