Fluid-to-fluid modeling of supercritical water loops for stability analysis

The use of supercritical water as coolant/moderator may induce oscillations in the supercritical light water reactor similar to the density wave oscillations observed in boiling water reactors (BWRs). In order to experimentally investigate the stability of supercritical reactors, a fluid-to-fluid downscaled facility is proposed. It is found that with an appropriate mixture of refrigerants R-125 and R-32, the dimensionless enthalpy and density of the supercritical water can be accurately matched for all relevant operational conditions of the reactor. Moreover, the inertia distribution, the friction factor distribution and the heat transfer mechanism are taken into account in the modeling. As a result of the proposed downscaling, the operational pressure, temperature and power are considerably smaller than those of a water-based system, which in turn helps reducing the construction and operational costs of a test facility. Finally, it is found that the often used modeling fluid supercritical CO₂ cannot accurately represent supercritical water at reactor conditions.     

Dichlorvos space treatment for protection of packaged flour against insect infestation

Dichlorvos vapor was applied weekly from dichlorvos-impregnated resin pellets into 42·5 m³ (1500 ft³) chambers. The chambers contained insect-free flour packaged in cotton sheeting, and in multiwall paper bags stacked at various distances from similar bags of infested flour. The dichlorvos concentration attained in the chambers from the weekly application of vapor was about 3 μg/1. After 5 months of storage, the number of insects found in the flour indicated that the dichlorvos applications retarded the infestation of flour in cotton bags and prevented the infestation of flour in the multiwall paper bags. Chemical analysis showed that dichlorvos residues were less than 0·1 ppm in the flour and, in general, less than 1·1 μg/dm² (10 μg/ft²) on the packaging materials.     

Pathophysiological changes after traumatic brain injury: comparison of two experimental animal models by means of MRI

In an experimental study MRI was used to compare the pathophysiological changes of brain tissue after lateral fluid percussion injury (FPI) versus cold injury (CI) as models of traumatic brain injury (TBI). Two groups of Sprague-Dawley rats (n = 23) were subjected to mild FPI, respectively, CI localized over the right parietal cortex. MRI was performed at different time points including Tlw, T2w and Tlw-CE (Gd-DTPA 0.2 mmol/kg BW) sequences as well as perfusion-weighted imaging with calculation of regional cerebral blood volume (rCBV) and regional cerebral blood flow (rCBF). T2w and Tlw-CE images showed hyperintense areas in the traumatised cortex demonstrating brain edema and blood-brain barrier (BBB)-breakdown increasing up to 12 h. Perfusion-weighted imaging demonstrated a significant decrease of rCBV and rCBF in the ipsilateral cortex of CI animals compared with the contralateral hemisphere. In contrast, rats of the FPI group showed only slight differences in rCBF and rCBV comparing the left and right cortex. The results of our study confirm that both mild FPI and CI produced focal brain edema with concomitant breakdown of the BBB as a model of TBI. Since differences regarding perfusion are much more pronounced in CI our results suggest that, this model more likely seems to reflect pathophysiological changes of brain ischemia, whereas FPI seems to be better suited to model the pathophysiological characteristics of TBI.     

Oberflächenwellen‐Strukturen in Cu‐Damaszentechnologie

Application of the Copper Damascene Technology to Surface Acoustic Wave Structures A novel fabrication technology for power SAW devices with embedded interdigital transducers of a copper thin film system (copper damascene technology) is described. Such SAW structures have a significantly higher power durability and lifetime compared to usual Al‐based transducers. These properties denote that they become attractive for new applications where high SAW amplitudes and a flat surface of the device are required for these applications.     

Investigating the ESBWR stability with experimental and numerical tools: A comparative study

In this work, the stability of the Economic Simplified Boiling Water Reactor (ESBWR) has been studied by using a Freon-134a based experimental facility (GENESIS) and two system codes, being ATHLET 2.0a and (to a lesser extent) TRACG. During setting up the GENESIS facility and the numerical calculations, a great effort has been made to approximate the ESBWR system as accurate as possible.In general, it was found that a sufficient margin to instability exists regarding the ESBWRs nominal point. In addition, a comparison was made between the numerical and experimental results for both the thermal-hydraulic system and the reactor system. Deviations were found between the numerical and experimental results, in spite of the close similarity between the GENESIS facility and the definition of the ESBWR system in the system code. This result shows that predictions regarding real nuclear reactors, based on modeled systems, should be taken with care.     

Urban anglers' perception of risk from contaminated fish.

The Newark Bay Complex includes the Newark Bay, tidal portions of the Hackensack River, Passaic River, Arthur Kill, and Kill van Kull. It is a highly industrialized urban area including five counties and more than 20 local governments with a large racially-mixed population of more than 3 million people. In 1982, research conducted by the New Jersey Department of Environmental Protection (NJDEP) showed elevated levels of chemical contaminants in five species of fish and one type of crab in the Newark Bay Complex. Subsequently, the State of New Jersey adopted advisories to guide citizens on safe consumption practices for fish and crabs. Since then, fish consumption advisories have been issued primarily through the Fish and Game Digest, a publication distributed by the state to licensed anglers. However, anglers in the Complex are not required to have a fishing license because the waters are marine. Therefore, most anglers in this area do not receive advisory information. To gain greater insight into the information sources and risk perceptions of urban anglers, a survey was conducted of 300 anglers at 26 fishing and crabbing locations in the Newark Bay Complex during the summer and early fall of 1995. The objectives of the study were to learn anglers': (1) knowledge of fish consumption advisories; (2) belief in the advisories; (3) perception of how safe fish are to eat; (4) sources for information about fish and fishing; and (5) sources for information on fish consumption advisories. The study concluded that while 60% had heard about advisories, they either did not believe or were unconcerned about health effects from eating contaminated species. In addition, the most used source for information about fish and fishing was other fishermen, while newspapers were selected as a source for information about community news, health, and food safety.     

Dissolution of platinum in methoxy propionitrile containing LiI/I2

The stability of vapour deposited Pt and Pd as electrocatalysts on fluorine doped, tin oxide coated glass for the use as counter electrodes in dye senzitized electrochemical solar cells has been investigated. The electrocatalytically active layers did not seem to be chemically stable in an electrolyte consisting of LiI and I₂ dissolved in methoxy propionitrile. Thermodynamical calculations suggest the dissolution of Pt and Pd from the electrode surface to be caused by the formation of PtI₄ and PdI₆. Formation of complex species as PtI²⁻₄ and PdI²⁻₄ is less thermodynamically favoured, but PtI²⁻₄ may also be present in the solution.