Behavior Of Plants In Unventilated Chambers

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142325/1/ajb205503.pd

Observations from a prototype implementation of the Common APSE Interface Set (CAIS)

This paper presents an overview of the Common Ada Programming Support Environment (APSE) Interface Set (CAIS), its purpose, and its history. The paper describes an internal research and development effort at the Mitre Corporation to implement a prototype version of the current CAIS specification and to rehost existing Ada software development tools onto the CAIS prototype. Based on this effort, observations are made on the maturity and functionality of the CAIS. These observations support the government's current policy of publicizing the CAIS specification as a baseline for public review in support of its evolution into a standard which can be mandated for use as Ada is today

THE MURMANSK INITIATIVE - RF: 1994-1999 NEARING THE FINISH LINE.

''The Murmansk Initiative - RF'' is a tri-lateral project developed to support Russia's ability to meet the London Convention's prohibition on ocean disposal of radioactive waste. The Initiative, under a tripartite agreement, has upgraded an existing low-level liquid radioactive waste treatment facility, increasing capacity from 1,200 m{sup 3}/year to 5,000 m{sup 3}/year, and expanded capability to treat liquids containing salt (up to 10 g/L). The three parties to the agreement, the Russian Federation, Norway, and the United States, have all contributed the project. All construction has been provided by Russia. Construction of mechanical systems (piping and valves, pumps, sorbent columns, settling tanks, and surge tanks) is nearing completion, with instrumentation and control (I&C) systems currently being installed. Delays to the I&C installation have occurred because changes in system specifications required additional U.S. supplied computer control equipment to be purchased, and clearance through customs (both U.S. and Russian) has been slow. Start-up testing has been limited to testing of isolated sub-systems because of the delays in the I&C installation. The current state of the Russian economy and completion of a cementation unit, which was not part of the original tri-partite agreement, have hampered final construction activities. Russian regulatory authorities have stated that final licensing for expanded capacity (5,000 m{sup 3}/year) would not be given until the cementation unit was on-line. Completion of the project is now scheduled for August 1999

Electronic structure, phase stability and chemical bonding in Th2_2Al and Th2_2AlH4_4

We present the results of theoretical investigation on the electronic structure, bonding nature and ground state properties of Th$_2$Al and Th$_2$AlH$_4$ using generalized-gradient-corrected first-principles full-potential density-functional calculations. Th$_2$AlH$_4$ has been reported to violate the "2 \AA rule" of H-H separation in hydrides. From our total energy as well as force-minimization calculations, we found a shortest H-H separation of 1.95 {\AA} in accordance with recent high resolution powder neutron diffraction experiments. When the Th$_2$Al matrix is hydrogenated, the volume expansion is highly anisotropic, which is quite opposite to other hydrides having the same crystal structure. The bonding nature of these materials are analyzed from the density of states, crystal-orbital Hamiltonian population and valence-charge-density analyses. Our calculation predicts different nature of bonding for the H atoms along $a$ and $c$. The strongest bonding in Th$_2$AlH$_4$ is between Th and H along $c$ which form dumb-bell shaped H-Th-H subunits. Due to this strong covalent interaction there is very small amount of electrons present between H atoms along $c$ which makes repulsive interaction between the H atoms smaller and this is the precise reason why the 2 {\AA} rule is violated. The large difference in the interatomic distances between the interstitial region where one can accommodate H in the $ac$ and $ab$ planes along with the strong covalent interaction between Th and H are the main reasons for highly anisotropic volume expansion on hydrogenation of Th$_2$Al.Comment: 14 pages, 9 figure