How Might Synthetic Fuels from Coal Affect Natural Resources and Environment?

Energy self-sufficiency for the U. S. requires substantially increased use of coal. Direct combustion of coal without adequate environmental controls, as would occur if coal were used as a fuel for homes and offices throughout the country, would result in severe air pollution problems„ Synthetic fuels from coal such as methane, low BTU gas, or hydrogen, when utilized by the homes and businesses as gas or as electricity from gas, will contribute a much smaller amount of air pollution. However, to make these synthetic fuels available, it is necessary to mine more coal than would have to be mined for direct combustion, as the conversion processes all have energy losses. It is also necessary to make more extraction equipment, more fuels processing equipment and more distribution equipment which places a heavier burden on mineral resources, with associated added requirements for energy to make the equipment. This paper explores the effects on energy resources, and the environment by carefully- taking account of extra coal needed, extra equipment required, and the associated environmental costs due to all forms of pollution resulting from the mining operation, conversion of coal to synthetic fuels, and the combustion of the synthetic fuels. Resource depletion and environmental impact are compared for the present system and a synthetic gas system which provides all of our electric power

User Experience Evaluation in BCI: Filling the Gap

Brain-computer interface (BCI) systems can improve the user experience (UX) when used in entertainment technologies. Improved UX can enhance user acceptance, improve quality of life and also increase the system performance of a BCI system. Therefore, the evaluation of UX is essential in BCI research. However, BCI systems are generally evaluated according to the system aspect only so there is no methodology to evaluate UX in BCI systems. This paper gives an overview of such methods from the human-computer interaction field and discusses their possible uses in BCI research

In-situ measurement of reactive hydrocarbons at Hohenpeissenberg with comprehensive two-dimensional gas chromatography (GC×GC-FID): use in estimating HO and NO₃

International audienceDuring a field campaign at the Meteorological Observatory Hohenpeissenberg (MOHp) in July 2004, volatile organic compounds (VOCs) were measured using comprehensive two-dimensional gas chromatography (GC×GC). Comparison to routinely made gas chromatography mass spectrometry (GC-MS) measurements showed good agreement for a variety of anthropogenic and biogenic ambient VOCs ranging in concentration from below the detection limit (0.1 pmol mol?1) to 180 pmol mol?1. Pronounced diurnal cycles were found for both the biogenic and anthropogenic compounds, driven for the most part by the daily rise and fall of the boundary layer over the station. For the reactive compounds (lifetimes 6molecules cm?3), which compares well to that measured at the site, 3.2±2.3×106molecules cm?3. The analysis was extended to the night time data to estimate concentrations for NO3 (1.47±0.2×108molecules cm?3), which is not measured at the site. The feasibility of this approach for environments dominated by emissions of short-lived VOCs to estimate ambient levels of radical species is discussed

The Hohenpeissenberg aerosol formation experiment (HAFEX): A long-term study including size-resolved aerosol, H2SO4, OH, and monoterpenes measurements

Ambient aerosol size distributions (>3 nm) and OH, H2SO4, and terpene concentrations were measured from April 1998 to August 2000 at a rural continental site in southern Germany. New particle formation (NPF) events were detected on 18% of all days, typically during midday hours under sunny and dry conditions. The number of newly formed particles correlated significantly with solar irradiance and ambient levels of H2SO4. A pronounced anti-correlatation of NPF events with the pre-existing particle surface area was identified in the cold season, often associated with the advection of dry and relatively clean air masses from southerly directions (Alps). Estimates of the particle formation rate based on observations were around 1 cm-3 s-1, being in agreement with the predictions of ternary homogeneous H2SO4-NH3-H2O nucleation within a few orders of magnitude. The experimentally determined nucleation mode particle growth rates were on average 2.6 nm h-1, with a fraction of 0.7 nm h-1 being attributed to the co-condensation of H2SO4-H2O-NH3. The magnitude of nucleation mode particle growth was neither significantly correlated to H2SO4, nor to the observed particle formation rate. Turn-over rate calculations of measured monoterpenes and aromatic hydrocarbons suggest that especially the oxidation products of monoterpenes have the capacity to contribute to the growth of nucleation mode particles. Although a large number of precursor gases, aerosol and meteorological parameters were measured, the ultimate key factors controlling the occurence of NPF events could not be identified

Seasonal and diurnal variations of particulate nitrate and organic matter at the IfT research station Melpitz

Ammonium nitrate and several organic compounds such as dicarboxylic acids (e.g. succinic acid, glutaric acid), some Polycyclic Aromatic Hydrocarbon (PAHs) or some n-alkanes are semi-volatile. The transition of these compounds between the gas and particulate phase may significantly change the aerosol particles radiative properties, the heterogeneous chemical properties, and, naturally, the total particulate mass concentration. To better assess these time-dependent effects, three intensive field experiments were conducted in 2008–2009 at the Central European EMEP research station Melpitz (Germany) using an Aerodyne Aerosol Mass Spectrometer (AMS). Data from all seasons highlight organic matter as being the most important particulate fraction of PM1 in summer (59%) while in winter, the nitrate fraction was more prevalent (34.4%). The diurnal variation of nitrate always showed the lowest concentration during the day while its concentration increased during the night. This night increase of nitrate concentration was higher in winter (ΔNO3− = 3.6 μg m−3) than in summer (ΔNO3− = 0.7 μg m−3). The variation in particulate nitrate was inherently linked to the gas-to-particle-phase equilibrium of ammonium nitrate and the dynamics of the atmosphere during day. The results of this study suggest that during summer nights, the condensation of HNO3 and NH3 on pre-existing particles represents the most prevalent source of nitrate, whereas during winter, nighttime chemistry is the predominant source of nitrate. During the summer 2008's campaign, a clear diurnal evolution in the oxidation state of the organic matter became evident (Organic Mass to Organic Carbon ratio (OM/OC) ranging from 1.65 during night to 1.80 during day and carbon oxidation state (OSc) from −0.66 to −0.4), which could be correlated to hydroxyl radical (OH) and ozone concentrations, indicating a photochemical transformation process. In summer, the organic particulate matter seemed to be heavily influenced by regional secondary formation and transformation processes, facilitated by photochemical production processes as well as a diurnal cycling of the substances between the gas and particulate phase. In winter, these processes were obviously less pronounced (OM/OC ranging from 1.60 to 1.67 and OSc from −0.8 to −0.7), so that organic matter apparently originated mainly from aged particles and long range transport

On the Solutions of the Lorentz-Dirac Equation

We discuss the unstable character of the solutions of the Lorentz-Dirac equation and stress the need of methods like order reduction to derive a physically acceptable equation of motion. The discussion is illustrated with the paradigmatic example of the non-relativistic harmonic oscillator with radiation reaction. We also illustrate removal of the noncasual pre-acceleration with the introduction of a small correction in the Lorentz-Dirac equation.Comment: 4 eps figs. to be published in GR

Rural continental aerosol properties and processes observed during the Hohenpeissenberg Aerosol Characterization Experiment (HAZE2002)

International audienceDetailed investigations of the chemical and microphysical properties of rural continental aerosols were performed during the HAZE2002 experiment, which was conducted in May 2002 at the Meteorological Observatory Hohenpeissenberg (DWD) in Southern Germany. Online measurements included: Size-resolved chemical composition of submicron particles; total particle number concentrations and size distributions over the diameter range of 3 nm to 9 ?m; gas-phase concentration of monoterpenes, CO, O3, OH, and H2SO4. Filter sampling and offline analytical techniques were used to determine: Fine particle mass (PM2.5), organic, elemental and total carbon in PM2.5 (OC2.5, EC2.5, TC2.5), and selected organic compounds (dicarboxylic acids, polycyclic aromatic hydrocarbons, proteins). Overall, the non-refractory components of submicron particles detected by aerosol mass spectrometry (PM1, 6.6±5.4 ?g m?3, arithmetic mean and standard deviation) accounted for ~62% of PM2.5 determined by filter gravimetry (10.6±4.7 ?g m?3). The relative proportions of non-refractory submicron particle components were: (23±39)% ammonium nitrate, (27±23)% ammonium sulfate, and (50±40)% organics (OM1). OM1 was closely correlated with PM1 (r2=0.9) indicating a near-constant ratio of non-refractory organics and inorganics. The average ratio of OM1 to OC2.5 was 2.1±1.4, indicating a high proportion of heteroelements in the organic fraction of the sampled rural aerosol. This is consistent with the high ratio of oxygenated organic aerosol (OOA) over hydrocarbon-like organic aerosol (HOA) inferred from the AMS results (4:1), and also with the high abundance of proteins (~3%) indicating a high proportion of primary biological material (~30%) in PM2.5. This finding was confirmed by low abundance of PAHs (?3) and EC (?3) in PM2.5 and detection of several secondary organic aerosol compounds (dicarboxylic acids) and their precursors (monoterpenes). New particle formation was observed almost every day with particle number concentrations exceeding 104 cm?3 (nighttime background level 1000?2000 cm?3). Closer inspection of two major events indicated that the observed nucleation agrees with ternary H2SO4/H2O/NH3 nucleation and that condensation of both organic and inorganic species contributed to particle growth

Negative microbiological results are not mandatory in deep sternal wound infections before wound closure†

OBJECTIVES To define the outcome of treatment for deep sternal wound infections (DSWIs) using direct wound closure (DC) or vacuum-assisted therapy (VAT) based on negative vs. positive microbiological results. METHODS Between 1999 and 2008, 7746 patients underwent median sternotomy for cardiac surgery at our institution. Patients were screened for DSWI and out of the cohort 159 were identified (2%). These patients were treated, either using DC or VAT with delayed wound closure. Outcomes were retrospectively analysed to determine the effect of negative cultures at the time of closure. RESULTS The indication for sternotomy was CABG 51%, isolated valve 18%, CABG/valve 18% and other related cardiovascular procedures 14%. Sixty-five percent of the wound infections was diagnosed during rehabilitation period. One hundred and five (66%) patients were treated with VAT vs. 54 (34%) patients with direct closure. Coagulase negative staphylococci were found in 48% of bacterial cultures. In 75% of the patients, the microbiological results were positive at time of wound closure (69.2% VAT vs. 87.0% direct closure, P=0.014). Out of 159 patients, 5.0% were with positive microbiological results at the time of closure readmitted vs. 5.1% with negative microbiological results (P=1.0). Patients with VAT stayed significantly longer in the hospital (mean 21±16 vs. 13±12, P=0.002). CONCLUSIONS Negative microbiological results are not mandatory before wound closure, as the rate of readmissions for recurrence of infection showed no difference between groups. Our results also suggest that shortening of VAT despite positive microbiological results may be feasibl