Underwater Breathing Apparatus

An independent closed circuit regenerative type of breathing apparatus has been developed for isolating the respiratory tract from the ambient medium for use during breathing by personnel working in underwater or polluted atmosphere. An oxygen reducer is used in the design of this apparatus for catering to the required flows of oxygen for breathing during use of the apparatus and thus avoiding oxygen poisoning. The paper describes some of the salient aspects of the breathing apparatus to be deployed for submariners and other diving personnel of the Indian Navy and its potential usefulness as a life saving equipment

H-1 NMR study of molecular dynamics and phase transitions in (CH3NH3) 2PbBr6 and [N(CH3)(4)](2)SeCl6.

The proton spin-lattice relaxation time (T-1) has been measured in methylammonium hexabromoplumbate, (CH3NH3)(2)PbBr6, in the range 77-450K and tetramethylammonium (TMA) hexachloroselenate, [N(CH3)(4) ](2)SeCl6 in the range 77-430K In (CH3NH3)(2)PbBr6, T-1 shows a slope change at 415K, a minimum at 215K, and a discontinuous jump at 167K In [N(CH3)(4)](2)SeCl6, T-1 shows a slope change at 340K and goes through a narrow symmetric minimum at 194K. Further, it exhibits a shoulder-like structure at 106K and goes through a broad minimum at 85K. Motional parameters such as activation energy and preexponential factor have been evaluated for the reorientational motion of CH3-NH3 groups and the TMA ion in different phases