MATHEMATICAL MODELLING OF A ROTARY SWIRL CYCLONE SCRUBBER

A Rotary Swirl Cyclone Scrubber (RSCS) is a device designed to remove SO₂ and ash from the combustion products of an entrained-flow gasifier. It uses a combination of highly swirling flow and water sprays to produce high heat and mass transfer rates. In order to develop a better understanding of the operation of this device, modelling has been performed using an extended version of CFX-F3D. Simulations have been performed to examine the flowfield in the device and to determine SO₂ and ash capture efficiencies. The simulations show that the water jets used to remove the SO₂ from the gas completely change the direction or swirl in the device, resulting in a highly turbulent flow. The experimental SO₂ capture efficiency and the outlet temperature are well reproduced using a water droplet size of 60 μm, with this value being determined via fitting to a particular experiment. Predictions of ash particle capture are found to be in good agreement with the experimental data.     

Sequence Similarity and Cross-Reactivity of a Diels–Alder Catalyst and an Anti-Progesterone Antibody

Antibody 1E9 catalyzes the bimolecular Diels–Alder reaction between tetrachlorothiophene dioxide and N-ethylmaleimide with high catalytic efficiency. The genes encoding the heavy and light chains were cloned, sequenced, and expressed as a mouse/human chimera in a murine hybridoma. Comparison with the closely related and structurally characterized anti-progesterone antibody DB3 has permitted identification of the residues that are likely to line the binding cavity. In addition to confirming the expectation of a highly hydrophobic active site, modeling results suggest that shape complementarity, achieved mainly through van der Waals rather than hydrogen bonding or electrostatic interactions, is likely to be the dominant factor in achieving effective preorganization of the substrates for catalysis. These conclusions can now be investigated through targeted mutagenesis of the putative active site residues exploiting the mammalian expression system.     

Introduction to the special section on chaos theory and psychological assessment.

The premise of the articles in this special section is that the goals of psychological assessment, and the explanations and predictions made on the basis of it, can be advanced by assimilating several concepts from nonlinear dynamical modeling and chaos theory—concepts and mathematical models that have been discussed most frequently in economics, ecology, biology, and physics. The concepts presented in the two articles by Heiby (1995a, 1995b, in this issue) and the article by Haynes, Blaine, and Meyer (1995, in this issue) are brief introductions to a small set of ideas from much larger domains (e.g., Burton, 1994). More extensive discussions of nonlinear dynamics and chaos can be found in several recently published books (Baker & Gollub, 1990; ?ambel, 1993; Haynes, 1992; Vallacher & Nowak, 1994; von Eye, 1990; Wei, 1990). These three articles borrow ideas that have been useful in other disciplines to address several phenomena that have been problematic in psychological assessment: (a) Behavior and causal variables often change rapidly in magnitude, rate, and form over time—they are dynamic; (b) these changes are often unpredictable, nonlinear, and discontinuous; and (c) it is often difficult to establish causal relationships for behavior change. The articles suggest several measurement strategies to increase our abilities to predict and explain the dynamical, nonstationary, and nonlinear phenomena that are often the targets of psychological assessment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An application example of the NBS robot control system

The National Bureau of Standards, Industrial Systems Division, has designed The Robot Control System where high level goals are decomposed through a succession of levels, each producing strings of simpler commands to the next lower level. The bottom level generates the drive signals to the robot, gripper, and other actuators. Each control level is a separate process with a limited scope of responsibility, independent of the details at other levels, thus providing a foundation for future modular, “plug compatible” hardware and software for robotics and other real-time sensory interactive control applications.To aid in specifying the required task decomposition and task processing, a programming language and program developing environment have been implemented. Programs at each control level are expressed as state tables, and the programming environment permits the generation, editing, emulation, and evaluation of these state tables. The control system is completely interactive, allowing the system to run freely, or be single-stepped to any level of detail.This paper describes the first application of The NBS Robotol Control System in a realistic factory environment, fully integrated with a workstation control system, database system, safety computer, gripper control system, vision system, and network.     

Effect of oestrogen receptor status and time on the intra-tumoural accumulation of tamoxifen and N-desmethyltamoxifen following short-term therapy in human primary breast cancer

Chronic in utero methamphetamine treatment, throughout gestation in rats, resulted in alterations in both behavior and brain monoamine function in the adult offspring. The higher dose of methamphetamine (10 mg/kg/b.i.d.) caused a significant decrease in square crossing and rearing in an open field, as well as a regional increase of serotonin and dopamine uptake sites. In contrast, the lower dose of in utero methamphetamine (2 mg/kg/b.i.d.) resulted in a significant decrease in regional densities of serotonin and dopamine uptake sites, and only decreased rearing behavior. Across treatment groups, there were significant correlations between open-field square crossing activity and the number of uptake sites in specific brain areas. Other measured behaviors, such as the neonate righting reflex and the adult Morris water maze performance, were unaffected by either in utero drug regimen. These results are discussed in terms of the known neurotoxicity of amphetamines and the ability of the immature nervous system to compensate for fetal exposure to methamphetamine.     

Assessing retirement satisfaction and perceptions of retirement experiences.

A 2-part investigation developed a measure of retirement as a life transition. Study 1 generated items from interviews with retirees (n?=?40) and service providers. Item analysis with recent retirees (n?=?86) produced a 51-item Retirement Satisfaction Inventory assessing 6 areas: preretirement work functioning, adjustment and change, reasons for retirement, satisfaction with life in retirement, current sources of enjoyment, and leisure and physical activities. Study 2 examined a heterogeneous sample of men (n?=?159) and women (n?=?243) retirees. Factor analyses produced internally consistent subscales. Moderate, but acceptable, test–retest reliability was demonstrated. Satisfaction scores correlated with concurrent measures and, together with pre- and postretirement experiences, discriminated 4 groups of voluntary and involuntary retirees. Few effects related to gender, SES, length of retirement, and part-time employment were found. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dose-rate effects in silicon-implanted gallium arsenide from low to high doses

For implantation of silicon dopant into gallium arsenide, sheet resistance and damage increase as the ion dose rate increases in the high-dose regime (>5.0 × 10¹³ cm⁻²). But, in the low-dose regime (<5.0 × 10¹² cm⁻²), although damage still increases with dose rate, the sheet resistance decreases. This qualitative difference implies that there must be a crossover point between the low- and high-dose regimes in the effect of damage and defect formation on dopant activation. This paper describes experiments in which damage and silicon dose were independently varied through the crossover point. Thermal wave, ion channeling, Hall effect measurements, and transmission electron microscopy were used to characterize structural and electrical changes that occur near the crossover. In GaAs implanted with silicon (²⁹Si⁺) at doses between 3 × 10¹² and 6 × 10¹³cm⁻², it is shown that electrical activation for low dose rates first begins to exceed that for high dose rates at a dose of 2 × 10¹³ cm⁻². Rapid growth of Type I dislocations also begins near this same dose, suggesting that there may be a link between defect formation and the crossover to negative dose-rate effects in the high-dose regime.