Manufacturing of 50 kA superconducting transformer for ITER correction coil conductor test

To meet the specifications of International Thermonuclear Experimental Reactor correction coil (CC) conductor, a 50 kA superconducting transformer has been designed and manufactured to provide the short sample of the CC conductor the current. The transformer consists of two concentric layer-wound superconducting solenoids with the primary inside the secondary coil. In order to test the transformer, the two legs of the secondary coil were directly connected by superconducting cables. A 500 W/4.5 K refrigerator was used to provide the supercritical helium. The maximum current of 56.3 kA in the secondary coil loop was obtained.

Selective inhibition of isoprenylation of 21-26-kDa proteins by the anticarcinogen d-limonene and its metabolites

Limonene has chemotherapeutic activity against chemically induced rat mammary carcinomas, many of which contain activated ras genes. Given the recent discovery of the post-translational modification of p21ras and other cell growth-associated proteins by intermediates in the mevalonic acid pathway, and the common biochemical origins of limonene and these isoprene products, we investigated the effect of limonene on protein isoprenylation. NIH3T3 and human mammary epithelial cells were incubated with lovastatin and [2-14C]mevalonolactone in the absence and presence of limonene. Labeled proteins were then subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography. Limonene inhibited isoprenylation of a class of cellular proteins of 21-26 kDa, including p21ras and possibly other small GTP-binding proteins, in a dose-dependent manner in both cell lines. In contrast, limonene did not affect the isoprenylation of several other proteins, including nuclear lamins. Limonene is metabolized extensively in vivo but not in cultured cells. The two major rat serum metabolites of limonene, perillic acid and dihydroperillic acid, were more potent than limonene in the inhibition of isoprenylation. These results demonstrate that limonene selectively inhibits isoprenylation of 21-26-kDa proteins at a point in the mevalonic acid pathway distal to 3-hydroxy-3-methylglutaryl coenzyme A reductase, and they provide a plausible explanation for its chemotherapeutic activity. Inhibition of isoprenylation of proteins such as p21ras and other small GTP-binding proteins would alter their intracellular localization and, hence, disrupt their biological activity.

Polarization multiplexing applied to a fiber current sensor

The measurement of Faraday rotation can be made insensitive to linear birefringence by time multiplexing of different states of polarization at the input of the fiber. This offers a new possibility of overcoming the linear birefringence effect in fiber current sensors. Experimental results and the measurement accuracy versus the quality of the optical components used are presented.

Temperature dependence of bend- and twist-induced birefringence in a low-birefringence fiber

The temperature dependence of the bend- and twist-induced birefringence in LB600 low-birefringence fiber has been measured at lambda = 0.633 microm. The relative temperature dependence B = (1/beta)dbeta/dT of the bend-induced birefringence beta was found to be (5.7 +/- 0.2) x 10(-4) K(-1) over a temperature range from -5 to 70 degrees C. The relative temperature dependence A = (1/g)dg/dT of the twist-induced birefringence g was found to be (4.95 +/- 0.25) x 10(-4) K(-1) (between 22 and 150 degrees C). The measured values of A and B are in accordance with a relative temperature dependence (1/C)dC/dT of the stress-optic coefficient C equal to (4.2 +/- 0.2) x 10(-4) K(-1).