Abstract: There is provided a process of effectively separating pentafluorethane (HFC-125) out of a mixture of HFC and chloropentafluoroethane (CFC-115). When the mixture of HFC-125 and CFC-115 is subjected to extractive distillation so as to obtain concentrated HFC-125, methanol, ethanol, butanol, propyl alcohol, pentafluoropropanol, tetrafluoropropanol or acetone is used as an extractant, whereby CFC-115 is obtained as a distillate product and a mixture of HFC-125 and the extractant is separated from HFC-125 by distilling the mixture and re-used in the extractive distillation.

Abstract: The purification of pentafluoroethane (HFC-125) which is composed of a process A, in which an unpurified mixture (1), containing at least chloropentafluoroethane (CFC-115) and pentafluoroethane (HFC-125) is reacted with hydrogen (4) in the presence of a catalyst in gas phase to reduce the said chloropentafluoroethane (CFC-115); and a process B, in which a reaction mixture produced by the preceding reaction is separated into a first mixture (3) composed mainly of hydrogen and a second mixture (2), composed mainly of pentafluoroethane (HFC-125). In this method, purification is performed by adding the said first mixture (3) to the said unpurified mixture (1) in a state that the hydrogen chloride is removed from the first mixture (3) in process B until the level of hydrogen chloride drops to 0.

Abstract: An MR imaging method uses NMR phenomenon, and includes a number of steps. These steps include emitting an excitation RF pulse and a plurality of refocus RF pulses to an object to generate a plurality of spin echo signals successively, and applying slice selecting gradient field pulses simultaneously with the RF pulses, respectively, for selecting slice planes. A polarity of reading gradient field pulses is switched a plurality of times to generate a plurality of gradient echo signals. A phase-encoding gradient field pulse, providing a different integrated phase encode amount, is applied to each of a plurality of echo signals generated after each of the spin echo signals is generated. The reading gradient field pulses are applied in timed relationship with generation of the spin echo signals. A pulse sequence consisting of the above steps is repeated while varying the integrated phase encode amount.

Abstract: A new 3,3-dichloro-1,1,1,2,2,4,4,5,5,5-decafluoropentane as a precursor of alternatives of refrigerants, etc.A method to obtain the target products at high yield and high selectivity by reacting tetrafluoroethylene and difluorodichloromethane under the Lewis acid catalyst to produce the new compound and an economical method in a continuous reaction state.A production method of 1,1,1,2,2,4,4,5,5,5-decafluoropentane at high yield by reducing 3,3-dichloro-1,1,1,2,2,4,4,5,5,5-decafluoropentane.

Abstract: An MR imaging apparatus using NMR phenomenon includes a main magnet for generating a uniform static magnetic field in an imaging space, a first to a third gradient field coils, an RF coil for emitting an excitation RF pulse and a plurality of refocus RF pulses and detecting echo signals, an RF emitter for modulating and emitting the excitation RF pulse and refocus RF pulses with predetermined timing through the RF coil, and a slice-selecting gradient field pulse generator. A phase-encoding gradient field pules generator and a reading gradient field pulse generator are provided, along with a data collector for detecting, with a predetermined frequency (reference frequency), the echo signals detected by the RF coil, and collecting data therefrom. A phase detector determines phase differences of echo peaks in the echo signals with respect to the reference frequency, respectively.

Abstract: An MR imaging apparatus using NMR phenomenon includes a main magnet, a first to a third gradient field coils, a RF coil, a RF emitter, a slice-selecting gradient field pulse generator, a reading gradient field pulse generator, a phase-encoding gradient field pulse generator and a data processor. The phase-encoding gradient field pulse generator effects phase-encoding, such that phase-encoding gradient field pulses have varied strengths to vary integrated phase encode amounts of spin echo signals from a positive (or negative) value through zero to a negative (or positive) value according to an order of generation; to vary, in a reversed direction, integrated phase encode amounts of each group of gradient echo signals having the same place in an order of generation thereof within respective pulse intervals; and to give the integrated phase encode amounts of each group of gradient echo signals greater absolute values than the integrated phase encode amounts of the spin echo signals.

Abstract: A magnetic resonance imaging method for emitting a single excitation RF pulse and then a plurality of refocusing RF pulses to an examinee to generate echo signals successively.

Abstract: A novel monohalogenotrifluorooxetane of the formula: ##STR1## (wherein X is chlorine, bromine or iodine) which is prepared by reacting monohalogenotrifluoroethylene of the formula:CF.sub.2 .dbd.CFX (III)(wherein X is the same as defined above)with a compound having a --(CH.sub.2 O)-- unit.

Abstract: 2,2,3-trifluoropropionyl fluoride is prepared by opening the ring of tetrafluorooxetane in the presence of a catalyst. Analogously, a novel 2,2-difluoropropionic acid derivative of the formula:XCH.sub.2 CF.sub.2 COY (I)wherein X is chlorine, bromine, iodine, a group of the formula:R.sub.1 O-- (II)orR.sub.2 COO-- (III)wherein R.sub.1 R.sub.2 are each an aliphaic or halogenated aliphatic hydrocarbon group having 1 to 8 carbon atoms or an aromatic hydrocarbon group having 6 to 8 carbon atoms optionally bearing at least one substituent, or a group of the formula:X'CH.sub.2 CF.sub.2 CF.sub.2 O-- (IV)wherein X' is fluorine, chlorine, bromine, iodine, the group of the formula: R.sub.1 O--or R.sub.2 COO--; and Y is fluorine or a group of the formula:--OR.sub.3 (V)wherein R.sub.