Showing papers by "Indonesian Institute of Sciences published in 1993"

Selligueain A, a novel highly sweet proanthocyanidin from the rhizomes of Selliguea feei.

Abstract: Selligueain A, a novel sweet trimeric proanthocyanidin with a doubly linked A unit, has been isolated from the rhizomes of Selliguea feei collected in Indonesia. The structure of this substance was established as epiafzelechin-(4 beta-->8, 2 beta-->O-->7)-epiafzelechin-(4 beta-->8)-afzelechin [1], on the basis of a combination of spectral and chemical methods. The compound was not acutely toxic for mice and not mutagenic in a forward mutation assay utilizing Salmonella typhimurium strain TM677. Selligueain A [1] was rated by a taste panel as exhibiting about 35 times the sweetness intensity of a 2% w/v aqueous sucrose solution, and at a concentration of 0.5% w/v in H2O was perceived as pleasant-tasting rather than astringent.

Cytotoxic constituents of the roots of the indonesian medicinal plant Fibraurea chloroleuca

Abstract: Three protoberberine alkaloids, berberine chloride, berberrubine chloride and thalifendine chloride were isolated from the roots of Fibraurea chloroleuca Miers, and found to show significant cytotoxic activity with one or more human cancer cell-lines and cultured P-388 cells. A phytoecdysteroid, 20-hydroxyecdysone, was also isolated as a noncytotoxic compound. Based on comparison with previous investigations, different collections of F. chloroleuca roots appear to exhibit considerable variation in their alkaloidal profiles.

Recovering errors from measurements involving solid angle

Abstract: Very little attention has been paid to errors in solid angle measurements and their effects on measurements such as those on light intensity or acoustical pressure. This paper concerns possible errors in solid angle having cone geometry. A mathematical technique is proposed as a method for determining the value of solid angle, and three methods of approach are also described. Error compensation in measurements of light intensity on the basis of the proposed method is discussed as a case study.

Steam-Injection Pressing Technology

Abstract: In order to establish the optimum steam-injection pressing technology, the characteristics of curing adhesives under high steam pressure, the temperature behavior in the particle mat core during steam-injection pressing, and the length of pressing time were investigated. A semi-continuous steam-injection press of test-plant scale was then developed and applied to the production of thick, low-density particleboard. The duration and pressure of steam injection with urea formaldehyde (UF) and urea-melamine formaldehyde (UMF) adhesives needed to be carefully determined for particleboard production by high-temperature steam-injection pressing, too-high steam temperatures resulting in a poor internal bond strength. On the other hand, the internal bond strength of those boards bonded with other resins was not perceptibly influenced by the steam temperature. The temperature in the middle layer of a particle mat with a thickness of 20 or 40 mm reached more than 100°C at the moment of steam injection, whereas it takes 4 and 11 minutes, respectively, in the case of hot pressing. The computer simulation predicts that only a few seconds of steam injection is required for a mat thickness within 100 mm to reach 100°C in the mat core. Isocyanate bonded particleboards with a thickness of 20 mm could be produced with a press time of around one minute. This corresponds to only about one-fifth of the press time of a conventional hot-platen press, and this effect of steam-injection pressing on shortening the press time would be greater for thicker board production. The newly developed semi-continuous, steam-injection press worked satisfactorily, and 100 mm thick low-density particleboards bonded with an isocyanate resin could be manufactured with a 90-second press cycle.