On-line carbon-in-ash monitors: Survey and demonstration

Fly ash unburned carbon (UBC) level is an important consideration for combustion efficiency as well as ash marketing. The presence of unburned carbon in fly ash has been shown to be a function of furnace design, coal quality, the ability of the pulverizer to grind the coal, and heat release rate. Boilers are designed to take these factors into consideration. However, the Clean Air Act Amendments of 1990 drove many utilities to switch coal supplies and install low NO{sub x} burners. Higher carbon-in-ash levels have been the result of these changes in coal quality and the staged combustion characteristics associated with low NO{sub x} burners. Over the past few years, several instruments for the on-line determination and monitoring of the unburned carbon content of ash samples have been developed. However, to date they have not been deployed widely in the U.S. despite potential uses for combustion optimization and as an aid in fly ash marketing. Based on the lack of publicly available performance and operation data available for the current CIAM (carbon-in-ash monitor) commercial offerings, Southern Company initiated a demonstration of several commercial technologies on its coal-fired units. As part of a DOE Clean Coal Project demonstrating advanced wall-fired combustion techniques for the reduction on NO{sub x} emissions from coal-fired boilers, the CAM, SEKAM and FOCUS systems were installed at Georgia Power Company`s Plant Hammond Unit 4. CAM and M&W instruments were also placed at Alabama Power Company`s Plant Gaston Unit 4. The testing of the instruments was conducted from November 1995 through August 1996

A Two-Chain Path Integral Model Of Positronium

We have used a path integral Monte Carlo technique to simulate positronium (Ps) in a cavity. The primitive propagator is used, with a pair of interacting chains representing the positron and electron. We calculate the energy and radial distribution function for Ps enclosed in a hard, spherical cavity, and the polarizability of the model Ps in the presence of an electrostatic field. We find that the positron distribution near the hard wall differs significantly from that for a single particle in a hard cavity. This leads to systematic deviations from predictions of free-volume models which treat Ps as an effective, single particle. A virial-type estimator is used to calculate the kinetic energy of the particle in the presence of hard walls. This estimator is found to be superior to a kinetic-type estimator given the interaction potentials, cavity sizes, and chain lengths considered in the current study. (C) 2000 American Institute of Physics. [S0021-9606(00)50447-4]

Comparison of two non-primitive methods for path integral simulations: Higher-order corrections vs. an effective propagator approach

Two methods are compared that are used in path integral simulations. Both methods aim to achieve faster convergence to the quantum limit than the so-called primitive algorithm (PA). One method, originally proposed by Takahashi and Imada, is based on a higher-order approximation (HOA) of the quantum mechanical density operator. The other method is based upon an effective propagator (EPr). This propagator is constructed such that it produces correctly one and two-particle imaginary time correlation functions in the limit of small densities even for finite Trotter numbers P. We discuss the conceptual differences between both methods and compare the convergence rate of both approaches. While the HOA method converges faster than the EPr approach, EPr gives surprisingly good estimates of thermal quantities already for P = 1. Despite a significant improvement with respect to PA, neither HOA nor EPr overcomes the need to increase P linearly with inverse temperature. We also derive the proper estimator for radial distribution functions for HOA based path integral simulations.Comment: 17 pages, latex, 6 postscript figure

Graphene transistors are insensitive to pH changes in solution

We observe very small gate-voltage shifts in the transfer characteristic of as-prepared graphene field-effect transistors (GFETs) when the pH of the buffer is changed. This observation is in strong contrast to Si-based ion-sensitive FETs. The low gate-shift of a GFET can be further reduced if the graphene surface is covered with a hydrophobic fluorobenzene layer. If a thin Al-oxide layer is applied instead, the opposite happens. This suggests that clean graphene does not sense the chemical potential of protons. A GFET can therefore be used as a reference electrode in an aqueous electrolyte. Our finding sheds light on the large variety of pH-induced gate shifts that have been published for GFETs in the recent literature

Lending Crowdfunding : Principles and Market Development

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Queer Touch Between Holy Women: Julian of Norwich, Margery Kempe, Birgitta of Sweden, and the Visitation

Under embargo until: 2021-12-17This essay takes a new approach to the well-known meeting between two late-medieval English visionary women, Margery Kempe and the anchoress Julian of Norwich, as described in The Book of Margery Kempe. In this analysis their conversation subtly evokes a long history of women concentrating their subversive power through intimate, spiritual exchange, a history reaching back to the Biblical Visitation scene and expressed in its medieval artistic and literary instantiations. A queer reading illuminates the way that such female same-sex relationships challenge patriarchal systems by offering a privileged access to God outside clerical supervision. By examining Margery and Julian’s encounter, Luke’s Visitation passage, its depiction in a late-medieval Book of Hours, and comparing two different Middle English translations of a Visitation vision in Birgitta of Sweden’s Revelations, the full transgressive effect of queer touch between women—or even its unspoken possibility—emerges.acceptedVersio

How Common is Common Human Reason?:The Plurality of Moral Perspectives and Kant’s Ethics

In his practical philosophy, Kant aims to systematize and ground a conception of morality that every human being already in some form is supposedly committed to in virtue of her common human reason. While Kantians especially in the last few years have explicitly acknowledged the central role of common human reason for a correct understanding of Kant’s ethics, there has been very little detailed critical discussion of the very notion of a common human reason as Kant envisages it. Sticker critically discusses in what ways Kant is committed to the notion that there are certain rational insights and rational capacities that all humans share, and thus investigates critically how Kant thinks moral normativity appears to the common human being, the rational agent who did not enjoy special education or philosophical training

Anti-Cancer Effect of HIV-1 Viral Protein R on Doxorubicin Resistant Neuroblastoma

Several unique biological features of HIV-1 Vpr make it a potentially powerful agent for anti-cancer therapy. First, Vpr inhibits cell proliferation by induction of cell cycle G2 arrest. Second, it induces apoptosis through multiple mechanisms, which could be significant as it may be able to overcome apoptotic resistance exhibited by many cancerous cells, and, finally, Vpr selectively kills fast growing cells in a p53-independent manner. To demonstrate the potential utility of Vpr as an anti-cancer agent, we carried out proof-of-concept studies in vitro and in vivo. Results of our preliminary studies demonstrated that Vpr induces cell cycle G2 arrest and apoptosis in a variety of cancer types. Moreover, the same Vpr effects could also be detected in some cancer cells that are resistant to anti-cancer drugs such as doxorubicin (DOX). To further illustrate the potential value of Vpr in tumor growth inhibition, we adopted a DOX-resistant neuroblastoma model by injecting SK-N-SH cells into C57BL/6N and C57BL/6J-scid/scid mice. We hypothesized that Vpr is able to block cell proliferation and induce apoptosis regardless of the drug resistance status of the tumors. Indeed, production of Vpr via adenoviral delivery to neuroblastoma cells caused G2 arrest and apoptosis in both drug naïve and DOX-resistant cells. In addition, pre-infection or intratumoral injection of vpr-expressing adenoviral particles into neuroblastoma tumors in SCID mice markedly inhibited tumor growth. Therefore, Vpr could possibly be used as a supplemental viral therapeutic agent for selective inhibition of tumor growth in anti-cancer therapy especially when other therapies stop working