The inhibition of the thermal oxidative degradation of polypropylene by various phenanthrols

All isomers of phenanthrol, 1-, 2-, 3-, 4-, and 9-phenanthrol, were prepared and the inhibitory effect of these compounds on the thermal oxidative degradation of isotactic polypropylene was examined by conventional oxygen uptake. The phenanthrols were found to be much more effective antioxidants than commercial 2,6-di-tert-butyl-4-methyl-phenol (abbreviated as BHT), and phenanthrene itself hardly showed any inhibitive effect. The effect of the phenanthrols was largely dependent on the position of the hydroxy group; the order of the effect was as follows: 1- > 4- > 2- > 3- > 9-phenanthrol > BHT. The phenanthrols were also good inhibitors of the radical polymerization of methyl methacrylate, and a fairly good correlation was observed between oxygen uptake and radical polymerization data.     

Anodic synthesis of 8-methylnonanoic acid and 8-methylnon-trans-6-enoic acid. The synthesis of dihydrocapsaicin and capsaicin (author''s transl)]

The author describes a rare case of the torsion of the pregnant fallopian tube with the macerated fetus and simultaneous intrauterine pregnancy. He points out dignostic difficulties in such cases.     

Active-site-directed inactivation of aromatase from human placental microsomes by brominated androgen derivatives

Several brominated androgen derivatives were tested for their ability to inactivate microsomal aromatase from term human placenta. In the experimental protocol, the microsomal homogenate was incubated either with androstenedione or a brominated derivative of androstenedione (16alpha-bromo-6-ketoandrostenedione, 16alpha-bromoandrostenedione, 7alpha-(3'-bromoacetoxypropyl)androstenedione, 6alpha-bromoandrostenedione, or 6beta-bromoandrostenedione) and reduced nicotinamide adenine dinucleotide phosphate in a nitrogen saturated buffer composed of glycerol, ethylenediaminetetraacetic acid, and dithiothreitol in tris(hydroxymethyl)aminomethane hydrochloride (pH 7.4) under nitrogen at 4 degrees C with shaking. After the incubation period, the microsomes were recovered by centrifugation and washed once before determining aromatase specific activity. The brominated androgen derivatives which inactivated aromatase were 7alpha-(3'-bromoacetoxypropyl)androstenedione and 6alpha-bromoandrostenedione. The structures of 6alpha- and 6beta-bromoandrostenedione were unequivocally established by single crystal x-ray diffraction techniques. The extent of the enzyme inactivation by 6alpha-bromoandrostenedione was linearly proportional to the logarithm of its concentration. The evidence that this inactivation occurs at the aromatase active site is that androstenedione, when coincubated with 6alpha-bromoandrostenedione, protected aromatase from this inactivation. Progesterone provided much less protection than androstenedione. Furthermore, both 6alpha- and 6beta-bromoandrostenedione are competitive inhibitors of androstenedione aromatization, as determined by a Lineweaver-Burk plot, and 6alpha-bromoandrostenedione gives the same type I cytochrome P-450 binding spectrum with placental microsomes as androstenedione. These data suggest that 6alpha-bromandrostenedione is effective as an active-site-directed inhibitor of placental microsomal aromatase.     

Degradation in soybean oil,sunflower oil and partially hydrogenated fats after food frying,monitored by conventional and unconventional methods

This paper aims to study discontinuous deep frying of potatoes, milanesas (breaded bovine Semimembranosus muscle) and churros (flour, water, milk, lemon and salt) in soybean oil, sunflower oil and partially hydrogenated fats, monitored by conventional and unconventional methods. With the exception of partially hydrogenated fat after 80.5 h of deep-frying churros, all the oils exceeded 25% of total polar compounds (TPC) and the content of polymeric and dimerized triacylglycerols were higher than 10%, prevailing thermal alterations. For none of the samples the percentage of free fatty acids exceeded 2% of oleic acid. The losses of tocopherols during frying reached 76.0%. Little significant alterations occurred in the fatty acids composition, iodine index calculated, saponification index and formation of trans isomers after frying. The rapid tests used to determine TPC, malondialdehyde and alkenals have proved to be viable alternatives to monitor the quality of frying oils.     

Behaviour of cobalt infiltration and abnormal grain growth during sintering of diamond on cobalt substrate

The infiltration behaviour of molten cobalt into a diamond powder compact was examined when the latter was placed on a cobalt disc and held at high pressure of 5.8 GPa and high temperature of 1350 to 1500° C. The larger the grain size of the starting diamond powder and the higher the holding temperature, the more easily cobalt infiltrated into the diamond compact. The infiltration is considered to occur because of the negative pressure in the voids formed between diamond grains. Although diamond powder was consolidated in this process of cobalt infiltration, abnormal grain growth was also observed in the boundary between cobalt and diamond compact because of the dissolution and precipitation process of the compact into molten cobalt.On leave from Chengdu University of Science and Technology, Chengdu, China.     

Catalytic efficiency of expressed aromatase following site-directed mutagenesis

A solid and cystic tumor (SCT) of the pancreas occurring in a 35-yr-old male is reported. Cut sections of the specimen revealed a solid, ill-defined mass measuring 2.5 x 2.3 x 2.0 cm, without cystic or necrotic changes. Histologically, the solid tumor consisted of small, round acidophilic cells invading the surrounding pancreatic parenchyma. The tumor cells were positive for alpha-1-antitrypsin and neuron-specific-enolase. Ultrastructural studies revealed clear nuclei with no zymogen, but immature secretory granules in the cytoplasm of the tumor cells, which had a junctional complex-like structure. These findings were consistent with the so-called solid and cystic tumor of the pancreas. There was neither a capsule surrounding the tumor nor a papillary structure, known to be characteristic findings of the SCT tumor. The small tumor reported in the present article might represent an early-stage SCT of the pancreas.     

Studies on changes in fatty acid composition and content of endogenous antioxidants during γ irradiation of rice seeds

Accelerated aging effects, induced by y irradiation, were investigated on the fatty acid composition of lipids and on the content of endogenous antioxidants of four Indica and four Japonica rice seeds with and without intact hull. While the linoleic acid content of the phospholipids decreased gradually with the increase in irradiation doses, there was a corresponding increase in the linoleic acid content of the free fatty acids. Such changes were drastic, especially in the case of Japonica rice seeds irradiated without intact hull. However, the neutral lipids were found to be resistant to γ irradiation. The α-tocopherol content was found to decrease (markedly) in rice seeds irradiated with or without hull, especially in the Japonica rice seeds. At a dose of 15 kGy only traces of a-tocopherol could be detected in Japonica and Indica rice seeds irradiated with and without intact hull. Oryzanol, a relatively weaker anti-oxidant, was found to be more resistant to oxidative damage than a-tocopherol. At 15 kGy, the oryzanol content ranged from 59 μg to 170 μg/g lipid in rice seeds irradiated with intact hull, while the corresponding value for rice seeds irradiated without hull was 52 μg to 153 μg/g lipid. The overall susceptibility to oxidative damage was less in Indica rice seeds, indicating that the antioxidative defense system offered better protection in overcoming oxidative stress in Indica rice hull than in Japonica rice hull.