Olivomycin and related antibiotics XXVIII. Monomeric composition of aureolic acid and proof that the antibiotics LA-7017 and mithramycin are identical to it
Summary1. It has been shown that aureolic acid, antibiotic LA-7017, and mithramycin are identical.2. It has been established that aureolic acid is a glycoside of chromomycinone (I) and contains the monosaccharides D-olivose (II), D-oliose (III), and D-mycarose (IV) in a ratio of 3 : 1 : 1.
Aureolic Acid Group of Anti-tumour Antibiotics
SINCE 1953 several antibiotics of similar biological and physico-chemical properties have been described. These are aureolic acid1, aburamycin2, LA-7017 (ref. 3), M5-18903 (ref. 4), chromomycin5, antibiotic 2410 (ref. 6), NSC A-649 (ref. 7), olivomycin8, mithramycin9 and antibiotics 232, 3014, 7193, 11296 (ref. 10) and SK-229 (ref. 11). Two members of this group, olivomycin and chromomycin, were subjected to extensive chemical research which resulted in the isolation and structural elucidation of their components, olivomycins A, B, C, D (ref. 12) and chromomycins A2, A3, A4 (ref. 13). The other members of the group, however, have been only scantily investigated.
Characterization of a tube-in-shell thermosyphon heat exchanger for solar water heating
Performance of a double-wall, natural convection, two-pass, tube-in-shell heat exchanger designed for use in a solar water heating system is measured. The heat exchanger is mounted along the length of a solar water storage tank. Flow of cold water on the shell side of the heat exchanger is driven solely by buoyancy forces. Hot side fluid is pumped. Flow rate, pressure drop and temperature data needed for a semi-empirical model of the heat exchanger are obtained. Performance is measured for forced convection, hot side volumetric flow rates of 0.016, 0.032 and 0.079 l/s. Temperature difference between hot and cold fluid at the inlets is varied from 0 to 75 degC. Measured values include thermosyphon and forced flow rates, temperature differences across the beat exchanger, vertical temperature distribution in the storage tank, and pressure drop due to shear on the thermosyphon side of the heat exchanger. Heat exchanger effectiveness and overall heat transfer area product (UA) are calculated. Thermosyphon mass flow rates are on the order of 0.01 kg/s. Although the low flow rates create thermal stratification of the water storage tank, they restrict energy transfer in the heat exchanger.