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Marines have a new tool to chart the course of their careers. Training and Education Command recently developed an overall 'roadmap' for a Marine's career--whether that career lasts four years, [...]

The Marine Corps Professional Reading Program got a booster shot Feb. 9 in what the Corps' top leader calls the first step toward reinvigoration of a key element of Marine [...]

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B1-type tantalum nitride (polycrystalline bulk state) was synthesized by shock compression. Shock-compression recovery experiments of the porous sample of tantalum nitride with a hexagonal structure (CoSn-type) were performed in the impact-velocity range up to 1.5kms-1. The instrumental chemical analysis, X-ray and electron diffraction experiments were carried out on the recovered tantalum nitride sample and the combustion-synthesized B1-type sample for comparison. The recovery rate of the B1 -type phase increased with increasing porosity, impact velocity and impactor thickness; among these above all the effect of porosity was most remarkable. Almost 100% recovery rate was achieved for the powder of 70% porosity impacted by a 2 mm thick tungsten plate with velocities above 1.4 kms-1. It was confirmed by chemical analysis that the nitrogen content did not change by shock compression. The chemical formulae of the shock-synthesized and combustioned-synthesized B1-type phases were estimated to be TaN0.96–0.99 and TaN1.13–1.16, 1.27–1.30, respectively. The lattice parameter of the shock-synthesized B1 -type (Fm3m) phase was ao=0.43363- + (1) nm. The results of X-ray and electron diffraction experiments also supported that the shock-synthesized B1-type tantalum nitride has a good stoichiometry compared with the combustion-synthesized ones.

Ozone resistance of highly saturated nitrile rubber (HNBR) has been studied; the effect of hydrogenation progress of HNBR was evaluated at various ozone test conditions such as static, dynamic, and sequential condi tions.Dependence of its hydrogenation progress on ozone resistance is discussed by using parameters of Ii,Iodine value which enhanced ozone resistance of base NBR, Io,Iodine value which demonstrates no cracks for 1000 hours, and Δ, the slope of ozone crack initiation time against Iodine value.Ozone resistance of HNBR was compared with that of typical specialty elastomers. Fully saturated HNBR exhibits excellent ozone resistance.

One of the most characteristic cell functions in plants is totipotency. Somatic embryogenesis can be regarded as a model system for the investigation of mechanisms of totipotency, because a high frequency and synchronous embryogenic system from single somatic cells has been established in carrot suspension cultures. Four phases are recognized in this process, and several molecular markers, viz. polypeptides, mRNAs, antigens against monoclonal antibodies, can be detected during the expression of totipotency, but they disappear during its loss. Four organ-specific genes have been isolated from hypocotyls and roots by differential screening. They were expressed preferentially after the globular-heart stages of embryogenesis, and were strongly suppressed by auxin. A CEM 1 gene was isolated by differential screening of embryogenic cell clusters. This gene was expressed strongly and transiently during the proglobular and globular stages. The sequence of CEM 1 was found to encode a polypeptide showing high homology to the elongation factor isolated from eucaryotic cells. Thus good progress is being made in understanding the basic mechanisms of somatic embryogenesis.

The benzocyclobutene (I) is used as a common material for the synthesis of the ester (VIII) and the pyran (XVI).