Chemical Constituents of Rhododendron lepidotum
Two new coumarin glycosides, 7-O-β-D-glucopyranosyl-8-methoxybenzopyranone (1) and 7-hydroxy-8-O-β-glycosylbenzopyranone ((2), are reported along with the isolation of 7,8-dihydroxy coumarin (daphnetin) from Rhododendron lepidotum (aerial part).
Triterpene and flavanone glycoside from Rhododendron simsii.
Antioxidative substances were isolated from the leaves of Rhododendron simsii. These were a triterpene and flavanone glycoside, together with the known matteucinol and two known benzoic acid derivatives. Their structures were characterized as 19,24-dihydroxyurs-12-en-3-one-28-oic acid and 7-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranosylmatteucinol by spectroscopic analysis.
Transformation from availability expression to failure frequency expression
The problem of computing the system's Failure Frequency is reduced to the problem of computing its Availability. This is performed by a transformation operator. However, the existing transformation operator is not practical because its transformation time increases exponentially with system size. To overcome this difficulty, this paper proposes a new method of transforming the Availability expression of a system into the corresponding Failure Frequency expression of the system. This method is based on a matrix approach using a 2 /spl times/ 2 matrix consisting of 0, Availability, and Failure Frequency in an appropriate manner. This transformation also enables algorithms for computing the Availability of a system to be transformed into algorithms for computing its Failure Frequency by replacing parameters and operations with matrix parameters and operations. The computation time after transformation is linear with respect to the original Availability algorithm. This implies that the problems of computing other well-known reliability measures including, Availability, Unavailability, MTBF, MTTR, MCT, Failure Rate, Failure Rate, and Failure Frequency, are reduced to only the Availability computation problem.