No abstract available

[en] A hypothetical magnetic drug targeting system, utilizing high gradient magnetic separation (HGMS) principles, was studied theoretically using FEMLAB simulations. This new approach uses a ferromagnetic wire placed at a bifurcation point inside a blood vessel and an externally applied magnetic field, to magnetically guide magnetic drug carrier particles (MDCP) through the circulatory system and then to magnetically retain them at a target site. Wire collection (CE) and diversion (DE) efficiencies were defined and used to evaluate the system performance. CE and DE both increase as the strength of the applied magnetic field (0.3-2.0 T), the amount of ferromagnetic material (iron) in the MDCP (20-100%) and the size of the MDCP (1-10 μm radius) increase, and as the average inlet velocity (0.1-0.8 m s^-1), the size of the wire (50-250 μm radius) and the ratio (4-10) of the parent vessel radius (0.25-1.25 mm radius) to wire radius decrease. The effect of the applied magnetic field direction (0 deg. and 90 deg. ) on CE and DE was minimal. Under these plausible conditions, CEs as high as 70% were obtained, with DEs reaching only 30%; however, when the MDCPs were allowed to agglomerate (4-10 μm radius), CEs and DEs of 100% were indeed achieved. These results reveal that this new magnetic drug targeting approach for magnetically collecting MDCPs at a target site, even in arteries with very high velocities, is feasible and very promising; this new approach for magnetically guiding MDCPs through the circulatory system is also feasible but more limited. Overall, this study shows that magnetic drug targeting, based on HGMS principles, has considerable promise as an effective drug targeting tool with many potential applications

[en] Space systems can be made to survive and operate in Earth's radiation belts. But to make them survive and operate, one has to understand them as systems, not just as a collection of individual piece parts. Whereas individual parts may upset or degrade in gain or even, in extreme cases, burn out, the system (properly designed) may continue to survive and operate. Space systems must, of course, be designed to survive and operate in the worst-case radiation environment in which they will be used. Achieving survivability for a space system is an iterative process. From the specified environment, simple, worst-case calculations of the dose in the electronics are made. Worst case means calculations made, often with many simplifying assumptions, that result in answers that are accurate or too high but not too low. A critical technique for achieving survivability is the selection of hardened parts. Parts are hardened for total ionizing dose, displacement damage, single-event upset/latchup, and dose rate effects. No space system hardening process can be considered to be complete without a significant amount of validation testing. Testing can be done at several different levels: piece part, circuit, box, and at the whole space system level

[en] This document summarizes the results of the phase 3 acceptance test of the 241-SY-101 Flexible Receiver System (FRS). The purpose of this acceptance test is to verify the sealing integrity of the FRS to ensure that the release of waste and aerosols will be minimized during the removal of the test mixer pump from Tank 241-SY-101. The FRS is one of six major components of the Equipment Removal System, which has been designed to retrieve, transport, and store the mixer pump. This acceptance test was performed at the 306E Facility in the 300 area from January 10, 1995 to January 17, 1995. The Phase 3 test consisted of two parts. Part one was a water leak test of the seal between the blast shield and mock load distribution frame (LDF) to ensure that significant contamination of the pump pit and waste interaction with the aluminum impact-limiting material under the LDF are prevented during the pump removal operation. The second part of this acceptance test was an air leak test of the assembled flexible receiver system. The purpose of this test was to verify that the release of hazardous aerosols will be minimized if the tank dome pressure becomes slightly positive during the decontamination of the mixer pump

[en] This Acceptance Test Procedure is for the 241-SY-101 Flexible Receiver System. The procedure will test the strength of the containment bag assembly by subjecting the bag assembly to a load test

[en] Quantum fluctuations developing in low dimensional S=1/2 magnetic systems have been a major research area in condensed matter physics in recent years. The 2D frustrated antiferromagnetic square lattice J₁-J₂ model has been intensively studied by theorists and a phase diagram where long range ordered regions are separated by so-called quantum spin liquid regions was proposed. Unluckily no examples of real compounds falling into the non ordered regions were found as the famous spin gap compounds SrCu₂(BO₃)₂ and CaV₄O₉ were shown to have the Shastry-Sutherland respectively the 1/5 depleted square lattice topology. Therefore much attention was paid to the new compound CuClLaNb₂O₇ which not only possesses a spin gap at low temperatures but which was believed to provide through its tetragonal symmetry a perfect square lattice for Cu²⁺ S=1/2 spins. CuClLaNb₂O₇ is part of the Dion-Jacobson family of layered compounds (CuX)A_n-1B_nO3_n+1 where e.g. X=Cl^-, Br^-, A=La³⁺, Ca²⁺, Sr²⁺, B=Nb⁵⁺, Ta⁵⁺ and n=2, 3, 4. Common structure elements of the series are Cu-halide layers separated by nonmagnetic perovskite like slabs build out of BO₆ octahedra. The possibility to influence the magnetic interactions by replacing the halide or more subtly by replacing one of the nonmagnetic cations was quickly realized to offer opportunities to study the magnetic phase diagram of the supposed square lattice. I will present recent results of neutron diffraction on the detailed structure and the magnetic behavior of four different compounds of this Dion-Jacobson series. It will be shown that the real symmetry of the n=1 compounds CuClLaNb₂O₇, CuClLaTa₂O₇ and CuBrLaNb₂O₇ is orthorhombic leading to a strong 4^th neighbor super-exchange coupling Cu-X-X-Cu which in the case of CuClLaNb₂O₇ leads to the formation of a dimer and the creation of a spin gap while increased interdimer couplings lead to the establishment of long range magnetic order in the other two compounds. The n=2 compound CuBrSr₂Nb₃O₁₀ does not show any orthorhombic distortion but split positions for Br- and for one oxygen site reflecting a local perturbation of the tetragonal symmetry. The helical magnetic order found at low temperature does not conform to the J₁-J₂ model but calls for the existence of a third coupling J₃. First results of a field dependent neutron diffraction study on this compound presenting a 1/3 magnetization plateau will be presented. (author)

[en] Hydrogen generation data obtained from IDMS runs PX4 and PX5 will be used to determine a bases for a deflagration/detonation simulation in the DWPF CPC. This simulation is necessary due to the new chemistry associated with the Late Wash/ Nitric Acid flowsheet and process modifications associated with the presence of H₂ in the offgas. The simulation will be performed by Professor Van Brunt from the University of South Carolina. The scenario which leads up to the deflagration/detonation simulation will be chosen such that the following conditions apply. The SRAT is filled to its maximum operating level with 9,600 gal of sludge, which corresponds to the minimum vapor space above the sludge. The SRAT is at the boiling point, producing H₂ at a very low rate (about 10 % of the peak) and 15 scfm of air inleakage is entering the SRAT. Then, the H₂ generation rate will be allowed to increase exponentially (catalyst activation) until it readies the peak H₂ generation rate of the IDMS run, after which the H₂ generation rate will be allowed to decay exponentially (catalyst deactivation) until the total amount of H2 produced is between 85 and 100% of that produced during the IDMS run

[en] This engineering task plan identifies the activities required for developing an ultra high pressure water drill system for installation of a saltwell screen in Tank BY-105. A water drill system is needed to bore through the hard waste material in this tank because of the addition of Portland cement in the 1960s and/or 1970s. The activities identified in this plan include the design, procurement, and qualification testing of the water drill along with readiness preparations including developing operating procedures, training Operations personnel, and conducting an assessment of readiness

[en] The Tank Waste Remediation System (TWRS) pretreatment facility project W-236B, known as the Initial Pretreatment Module (IPM), requires samples of supernatants and sludges from 200 Area tank farms for planned hot testing work in support of IPM design. The IPM project has proposed the development of several new sampler systems. These systems include a 0.5-l supernatant sampler, 3-l and 25-l supernatant and sludge samplers, and a 4,000-l sampler system. The 0.5-l sampler will support IPM sampling needs in the 1 to 3 l range starting in late fiscal year 1995. This sampler is intended to be used in conjunction with the existing 100 ml bottle-on-a-string. The 3-l and 25-l systems will be based on the Savannah River Site's sampler system and will support IPM sampling needs in the 3 to 100 liter range. Most of the hot testing required for design of the IPM must be accomplished in the next 3 years. This work plan defines the tasks associated with the development of a 0.5-l sampler system. This system will be referred to as the Half-Liter Supernatant Sampler System (HLSSS). Specifically, this work plan will define the scope of work, identify organizational responsibilities, identify major technical requirements, describe configuration control and verification requirements, and provide estimated costs and schedule. The sampler system will be fully operational, including trained staff and operating procedures, upon completion of this task

[en] Single particle inclusive experiments, and experiments that additionally measure a few correlations like the associated multiplicity, have provided the main contribution to our present understanding of high energy heavy ion collisions. The results from those experiments are in overall agreement with calculations of the cascade and hydrodynamical models. In the cascade model the collision of two nuclei is simulated as a cascade of nucleon-nucleon collisions using measured N-N cross sections. The hydrodynamical model, on the other hand, describes the nuclear collision as that of two fluids and makes use of a nuclear equation of state relating thermal and compressional energy densities to pressure. The pressure field dominates the expansion phase and leads to collective flow of the reaction products in a preferred direction. The observation of such effects in inclusive experiments is not well established. Collective effects that manifest themselves in the shape of the event in phase space are expected to be seen best in the new complete event detectors that measure the final state as exclusively as presently possible by measuring most of the charged particles emitted in the reaction. In addition, those detectors are well suited to test macroscopic concepts such as equilibrium and temperature. Global methods like the sphericity or thrust analysis take into account all the correlations measured in the event and are specially designed to determine the shape of an event in phase space and thus to define a reaction plane. Recent data from the Plastic Ball and the streamer chamber experiments, the first complete event detectors in use at the Bevalac, are presented in this report