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Connections between magnetic field induced optical activity and chirality have a rich and complicated history. Although the broken inversion symmetry of chiral molecules generates ‘natural’ optical activity, magnetic optical activity is generated by breaking time reversal symmetry. Therefore, molecular chirality is not expected to influence magnetic optical phenomena, such as Faraday rotation. Here we show that the chiral supramolecular assembly of polymers can result in large Faraday effects (Verdet constants = 10 5 °T –1 m –1 ). This strong Faraday rotation, which is amongst the highest value known for organic materials, originates from the so-called Faraday B term. Typically, B term Faraday responses are weak. We demonstrate large amplification through excitonic coupling within the supramolecular assembly, where the chirality of the system controls the assembly formed. These observations provide an alternative means to enhance the Faraday rotation of low symmetry systems and clarify the role of chirality in previous reported materials. The relation between magnetooptical activity and chirality has previously been confused. Chiral polymer films are presented with state-of-the-art Verdet constants, revealing the role of chirality, and a strategy to enhance the magnetooptical B term.

Wall channeling is a phenomena of interest for Pebble Bed Reactors (PBRs) where flow is diverted into high-porosity regions near the wall. This diversion of flow can have a significant impact on maximum fuel temperatures and core bypass flow. Porous media models that are currently used to model PBRs for design scoping and transient simulation are lacking in their capabilities to model the wall channel effect. Recent efforts at Penn State have produced an improved porous media pressure drop equation that is more capable of modeling the velocity variations caused by the wall channel effect in a porous media model. Several pebble beds were divided into concentric rings of \\(0.05D_{peb}\\), and average flow quantities and porosities were extracted for the ring. A correlation between the form loss coefficient and the local ring porosity was found, allowing for the addition of a correction factor to the form loss term of the KTA equation. The developed correlation was purely empirical, and thus a more thorough understanding of the underlying flow phenomena is desired. This study investigates geometric and flow features that can explain the observed correlation between the form coefficient and the local porosity that was used to generate the improved pressure drop equation. The solid surface area to volume ratio \\(S_v\\) along with the production of Turbulent Kinetic Energy (TKE) is analyzed. A relationship between \\(S_v\\) and the local porosity and an inverse relationship between the negative TKE production and the local porosity were found, pointing to the idea that inertial effects caused by different pore geometry in each ring contribute to the variation of the form constant with the local porosity.

Recent interest for the development of high-temperature gas reactors has increased the need for more advanced understanding of flow characteristics in randomly packed pebble beds. A proper understanding of these flow characteristics can provide a better idea of the cooling capabilities of the system in both normal operation and accident scenarios. In order to enhance the accuracy of computationally efficient, intermediate fidelity modeling, high-fidelity simulation may be used to generate correlative data. For this research, NekRS, a GPU-enabled spectral-element computational fluid dynamics code, was used in order to produce the high-fidelity flow data for beds of 1,568 and 45,000 pebbles. Idaho National Lab's Pronghorn porous media code was used as the intermediate fidelity code. The results of the high-fidelity model were separated into multiple concentric regions in order to extract porosity and velocity averages in each region. The porosity values were input into the Pronghorn model and the resulting velocity profile was compared with that from NekRS. Both cases were run with a Reynolds number of 20,000 based on pebble diameter. The Pronghorn results were found to significantly overestimate the velocity in the outermost region indicating that changes in the porosity alone do not cause the difference in fluid velocity. We conclude that further work is necessary to develop a more effective drag coefficient correlation for the near-wall region and improve predictive capabilities of intermediate fidelity models.

Nuclear power is a significant source of electricity in the United States, but the average U.S. nuclear power plant is around 40 years old. Safe management of spent nuclear fuel (SNF) is a crucial aspect of the back end of the nuclear fuel cycle. SNF dry storage systems are increasingly popular as they represent an effective solution in this area, given the absence of a final disposal system. In particular, the spent fuel cask system (dry cask method) provides a feasible solution for maintaining SNF (\\(\\sim\\)60 years) prior to the final disposal. The HI-STORM overpack and MPC-32 canister are the primary components of the HI-STORM 100 dry cask storage system. They remove heat from the system via natural circulation with no human intervention required. This characteristic provides passive heat removal while requiring little maintenance in dry cask storage systems. This project aims to validate and compare the capabilities of a thermal model of HI-STORM overpack developed using the Multiphysics Object-Oriented Simulation Environment (MOOSE) based on the author's previous study. MOOSE is an open-source framework developed by Idaho National Laboratory for multiscale, multiphysics simulations. This study will improve the capabilities of the thermal-hydraulic model of the HI-STORM dry cask storage system by producing high-fidelity results for the air circulation in the overpack. Large Eddy Simulations (LES) are performed using the open-source spectral element code NekRS, developed by Argonne National Laboratory (ANL), for simulating transitional and turbulent flows in complex geometries. NekRS will produce high-fidelity results for the HI-STORM overpack to assess the validity of the current thermal-hydraulic model.

The development of nuclear reactors that utilize pebble fuel has drastically increased the demand for improving the capabilities to simulate the packed beds found in these reactors. The complex flow fields found in a pebble bed make computational fluid dynamics (CFD) simulations time consuming and costly. Intermediate fidelity porous media models, however, are capable of approximating these flow fields in a much more computationally efficient manner. These models require the use of closures to capture the effects of complex flow phenomena without modeling them explicitly. This research employs data obtained from high-fidelity CFD simulations of a pebble bed to improve the drag closures used in porous media models in the near-wall region of the bed. Specifically, NekRS, a GPU-enabled spectral element CFD code, was used to simulate a bed of 1,568 pebbles at multiple Reynolds numbers. The case was divided into five concentric subdomains to extract radial profiles of the average porosity, velocity, and wall shear in each subdomain. A model consistent with the high-fidelity model was created in Idaho National Laboratory's Pronghorn porous media code and the KTA correlation was chosen as the drag closure of comparison. It was found that the KTA correlation overestimates the velocity in the near-wall region. An investigation of the drag coefficients between the two codes revealed that the KTA correlation underestimated the form factor in the outermost region while overestimating it in the inner four regions. This analysis in this work has revealed the underlying inaccuracy in the near-wall region of the KTA correlation and has set up the process for using high-fidelity simulation to predict more accurate drag coefficients a priori, rather than with a manual velocity-matching approach. This process will allow for the development of an improved drag closure for use in porous media models.

If the Orange Unified School District board majority is really so very interested in giving people freedom of choice, then I challenge the board to eliminate the practice of electing board members at-large.

Any advertising hack can tell you that the best way to sell a product to young people is to package it with hip music. Yet, at its convention a few weeks ago, the Republican Party lured young voters to its message with the sounds of Travis Tritt and four senators singing \"You're a Grand Old Flag.\" How's that for cool? In 1984, Neil Young spoke out in favor of Ronald Reagan and proclaimed he was voting Republican. This year the GOP should phone the \"Godfather of Grunge\" and find out how he plans to vote. After all, his song catalog is chock full of tunes perfect for Dole-Kemp campaign ads. For example: Back To School Jam with Keith Sweat, Bone Thugs-N-Harmony, Jodeci and SWV, Friday at the Rosemont Horizon: Headliner and New Jack [Kemp] Swing pioneer Keith Sweat has spent the last decade re-shaping the sound of contemporary R&B. His new, self-titled album purrs with velvety, satin-toned slow-jams. Bone Thugs-N-Harmony come to town with a hit record showcasing their ear-bending blend of noire soul and lilting rap polyphony. The four homeys of Jodeci deliver a guided tour of the libido via their slinky, slack funk. And SWV (Sisters With Voices) covers the pop end of the spectrum with old-school harmonizing and seductive street grooves. 6920 Mannheim Rd., Rosemont. 312-559-1212.

Over the last half century, Jamaican music and American R&B have traded ideas and innovations back and forth in a playful game of musical tag that has profoundly altered pop music in both countries. In the '60s and '70s, Jamaican dancehall emerged -- a style in which DJs talked, or \"toasted,\" over reggae rhythm tracks. This eventually provided the model for American rap. Maxi Priest's new album, \"The Man With the Fun,\" covers the usual gamut of straight pop, lovers rock and R&B balladry with slick, lushly arranged songs that dabble in modern dancehall with guest toasters like Shaggy and Buju Banton.

`We've been described as the Cranberries with boots on,\" remarks Scheer lead singer Audrey Gallagher in a distinctive Northern Irish brogue. \"But that's just a lazy comparison. You know: We're from Ireland, there's a girl singer and the rest of the band is boys.\" But while the comparison to the Cranberries is sloppy, just the phrase \"Cranberries with boots on\" does kind of suggest Scheer's fine blend of lilting pop hooks and abrasive guitar riffage. It's that tension between melody and turmoil that makes Scheer's \"Infliction\" album one of the year's better debuts. \"A lot of people notice that tension,\" agrees Gallagher. \"All five of us have different musical backgrounds, and there is a constant but unconscious pull between heaviness and lightness. . . . Everyone wants their corner in the music. As long as the results are good, that tension is good.\"

The RockCity Hamburg Showcase comes to the Double Door Saturday as part of a cultural exchange program between Chicago and its sister city Hamburg, Germany. The program, which will send several to-be-named local bands to Hamburg later this year, is sponsored by RockCity Hamburg, a pop music organization in Germany, and coordinated by the Goethe Institute here in Chicago. \"This is the first exchange of rock musicians as part of the sister city program,\" explains Angela Greiner, program coordinator at the Goethe Institute. \"Hamburg has a very vibrant rock music scene. So we are very excited about the project and fully supportive of it.\"