Advanced smoke meter development survey and analysis

Ideal smoke meter characteristics are determined to provide a basis for evaluation of candidate systems. Five promising techniques are analyzed in detail to evaluate compilance with the practical smoke meter requirements. Four of the smoke measurement concepts are optical methods: Modulated Transmission (MODTRAN), Cross Beam Absorption Counter (CBAC), Laser Induced Incandescence (LIN), and Photoacoustic Spectroscopy (PAS). A rapid response filter instrument called a Taper Element Oscillating Microbalance (TEOM) is also evaluated. For each technique, the theoretical principles are described, the expected performance is determined, and the advantages and disadvantages are discussed The expected performance is evaluated against each of the smoke meter specifications, and the key questions for further study are given. The most promising smoke meter technique analyzed was MODTRAN, which is a variation on a direct transmission measurement. The soot-laden gas is passed through a transmission cell, and the gas pressure is modulated by a speaker

Testing (beliefs about) social preferences: evidence from an experimental coordination game

We report experimental results on a simple coordination game in which two players can coordinate either on an equal distribution of payoffs or on a Pareto superior but unequal distribution of payoffs. We find that the higher the difference in individual payoffs, the less likely is a successful coordination on the Pareto superior distribution. While this is well in line with the recent models of inequity aversion, our results are best explained not by a preference for equality per se but rather by the belief that the opponent has such a preference

Managing Access to Biobanks:How Can We Reconcile Privacy and Public Interests in Genetic Research?

This article is concerned with the ultimate objectives of genetic biobanks set up to promote the public interest—being the sharing of samples and data for medical research—and the consequences for personal privacy of realising them. Our aim is to chart the values, interests and principles in play, to consider the challenges of realizing biobanking objectives on a global scale, and to propose viable ways forward that ensure, as far as possible, that access provisions remain fit for purpose throughout the entire life of a biobank, while adequately protecting the privacy interests at stake. It is argued that key features in any robust access model must include mechanisms to (a) maintain participant trust in management of the resource and to measure and respond to participants’ expectations, (b) facilitate and promote the sharing of benefits, and (c) respond timeously and effectively to new challenges

Complexity of fungal polyketide biosynthesis and function

Where does one draw the line between primary and secondary metabolism? The answer depends on the perspective. Microbial secondary metabolites (SMs) were at first believed not to be very important for the producers because they are dispensable for growth under laboratory conditions. However, such compounds become important in natural niches of the organisms, and some are of prime importance for humanity. Polyketides are an important group of SMs with aflatoxin as a well-known and well-characterized example. In Aspergillus spp., all 34 afl genes encoding the enzymes for aflatoxin biosynthesis are located in close vicinity on chromosome III in a so-called gene cluster. This led to the assumption that most genes required for polyketide biosynthesis are organized in gene clusters. Recent research, however, revealed an enormous complexity of the biosynthesis of different polyketides, ranging from individual polyketide synthases to a gene cluster producing several compounds, or to several clusters with additional genes scattered in the genome for the production of one compound. Research of the last decade furthermore revealed a huge potential for SM biosynthesis hidden in fungal genomes, and methods were developed to wake up such sleeping genes. The analysis of organismic interactions starts to reveal some of the ecological functions of polyketides for the producing fungi

Examination of Annular-Electrode Spark Discharges in Flowing Oxygen - An Overview

A parametric study of annular spark gaps, pressures, and spark discharges in flowing oxygen gas was performed with a Champion spark exciter. The range of the pressure-distance product for the experiment is from approximately 50 torr-cm to 2500 torr-cm. Measurements of breakdown voltage qualitatively trend with Paschen's curve. Spark duration remained constant until the pressure-distance product exceeded 200 torr-cm, and then steadily increased. The mean spark energy increases linearly with the pressure-distance on a log-log plot indicating that a definite power relationship exists. The distribution of sparks at low energies and low pressures is not Gaussian and has no dominant peaks. Moderate and high spark energies are bimodal, with the dominant mode near 80 mJ. As pressure increases, dominant and secondary modes approach the same probability

Chemical Kinetic Models for HCCI and Diesel Combustion

Predictive engine simulation models are needed to make rapid progress towards DOE's goals of increasing combustion engine efficiency and reducing pollutant emissions. These engine simulation models require chemical kinetic submodels to allow the prediction of the effect of fuel composition on engine performance and emissions. Chemical kinetic models for conventional and next-generation transportation fuels need to be developed so that engine simulation tools can predict fuel effects. The objectives are to: (1) Develop detailed chemical kinetic models for fuel components used in surrogate fuels for diesel and HCCI engines; (2) Develop surrogate fuel models to represent real fuels and model low temperature combustion strategies in HCCI and diesel engines that lead to low emissions and high efficiency; and (3) Characterize the role of fuel composition on low temperature combustion modes of advanced combustion engines

Examination of Annular-Electrode Spark Discharges in Flowing Oxygen Experimental Nuances

Microsecond sparks and the resulting plume of hot gas/plasma were examined against a parametric pressure-distance matrix. Schlieren imaging is used to capture the spatial and temporal location of spark discharge exhaust for two milliseconds. Low pressure and larger gap widths created the largest size and intensity signal for the spark-affected plumes. Experimental exit-plume velocities trend well with analytic predictions using a mean pressure between the chamber and atmospheric conditions. Due to the quadratic relation of the annulus area and gap width, larger gap width velocities are more accurately represented by analytic predictions using atmospheric pressure as the larger exit area restricts the flow less. The same pressure adjustment, when applied to breakdown voltages, improves data alignment with Paschens Curve

A flow cytometric assay to quantify \u3ci\u3ein vivo\u3c/i\u3e bacterial uptake by alveolar macrophages

Our laboratory has developed a flow cytometric assay to quantify alveolar macrophage (MФ) phagocytosis of bacteria within a live animal. MФs collected by bronchoalveolar lavage from rats infected transtracheally with Syto 9-labeled bacteria are fluorescently labeled for identification and analyzed by flow cytometry to quantify their bacterial uptake

Chemical Kinetic Modeling of Hydrogen Combustion Limits

A detailed chemical kinetic model is used to explore the flammability and detonability of hydrogen mixtures. In the case of flammability, a detailed chemical kinetic mechanism for hydrogen is coupled to the CHEMKIN Premix code to compute premixed, laminar flame speeds. The detailed chemical kinetic model reproduces flame speeds in the literature over a range of equivalence ratios, pressures and reactant temperatures. A series of calculation were performed to assess the key parameters determining the flammability of hydrogen mixtures. Increased reactant temperature was found to greatly increase the flame speed and the flammability of the mixture. The effect of added diluents was assessed. Addition of water and carbon dioxide were found to reduce the flame speed and thus the flammability of a hydrogen mixture approximately equally well and much more than the addition of nitrogen. The detailed chemical kinetic model was used to explore the detonability of hydrogen mixtures. A Zeldovich-von Neumann-Doring (ZND) detonation model coupled with detailed chemical kinetics was used to model the detonation. The effectiveness on different diluents was assessed in reducing the detonability of a hydrogen mixture. Carbon dioxide was found to be most effective in reducing the detonability followed by water and nitrogen. The chemical action of chemical inhibitors on reducing the flammability of hydrogen mixtures is discussed. Bromine and organophosphorus inhibitors act through catalytic cycles that recombine H and OH radicals in the flame. The reduction in H and OH radicals reduces chain branching in the flame through the H + O{sub 2} = OH + O chain branching reaction. The reduction in chain branching and radical production reduces the flame speed and thus the flammability of the hydrogen mixture