Rationale: Particulate air pollution is associated with cardiovascular morbidity. One hypothesized mechanism involves oxidative stress, systemic inflammation, and endothelial dysfunction.Objectives: To assess an intervention's impact on particle exposures and endothelial function among healthy adults in a woodsmoke-impacted community. We also investigated the underlying role of oxidative stress and inflammation in relation to exposure reductions.Methods: Portable air filters were used in a randomized crossover intervention study of 45 healthy adults exposed to consecutive 7-day periods of filtered and nonfiltered air.Measurements and Main Results: Reactive hyperemia index was measured as an indicator of endothelial function via peripheral artery tonometry, and markers of inflammation (C-reactive protein, interleukin-6, and band cells) and lipid peroxidation (malondialdehyde and 8-iso-prostaglandin F2α) were quantified. Air filters reduced indoor fine particle concentrations by 60%. Filtration was associat...

https://www.atsjournals.org/doi/pdf/10.1164/rccm.201010-1572OC

An Air Filter Intervention Study of Endothelial Function among Healthy Adults in a Woodsmoke-impacted Community

This review explains the potential use of the so-called “green coal” for biofuel production. A comparison between microalgae and other crops is given, and their advantages are highlighted. The production of biofuels from microalgae biomass is described, such as the use of algae extracts (e.g. biodiesel from oil, bioethanol from starch), processing the whole biomass (e.g. biogas from anaerobic digestion, supercritical fluid, bio-oil by pyrolysis, syngas by gasification, biohydrogen, jet fuel), as well as the direct production (e.g. alcohols, alkanes). Microalgal biomass production systems are also mentioned, including production rates and production/processing costs. Algae cultivation strategy and the main culture parameters are point out as well as biomass harvesting technologies and cell disruption. The CO2 sequestration is emphasised due to it’s undoubted interest in cleaning our earth. Life cycle analysis is also discussed. The algal biorefinery strategy, which can integrate several different conversion technologies to produce biofuel is highlighted for a cost-effective and environmentally sustainable production of biofuels. The author explains some of the challenges that need to be overcome to ensure the viability of biofuel production from microalgae. This includes the author’s own research, the use of microorganism fuel cells, genetic modification of microalgae, the use of alternative energies for biomass production, dewatering, drying and processing. The conclusion of the manuscript is the author’s view on the potential of microalgae to produce biofuels; the drawbacks and what should be done in terms of research to solve them; which technologies seem to be more viable to produce energy from algae; and which improvements in terms of microalgae, systems, and technologies should take place to enable the algae to fuels concept a reality.

Microalgae as a Feedstock for Biofuels

Substituting fossil fuels with bioenergy from forests, as well as thinning forests to reduce wildfire emissions, has been proposed as a means of cutting carbon dioxide emissions. A study based on inventory data for US West Coast forests now challenges this proposal, and finds that it could lead to 2–14% higher emissions than current management practices over the next 20 years.

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Regional carbon dioxide implications of forest bioenergy production

Life-cycle analyses, energy analyses, and a range of utilization efficiencies were developed to determine the carbon dioxide (CO2) and fossil fuel (FF) saved by various solid wood products, wood energy, and unharvested forests. Some products proved very efficient in CO2 and FF savings, while others did not. Not considering forest regrowth after harvest or burning if not harvested, efficient products save much more CO2 than the standing forest; but wood used only for energy generally saves slightly less. Avoided emissions (using wood in place of steel and concrete) contributes the most to CO2 and FF savings compared to the product and wood energy contributions. Burning parts of the harvested logs that are not used for products creates an additional CO2 and FF savings. Using wood substitutes could save 14 to 31% of global CO2 emissions and 12 to 19% of global FF consumption by using 34 to 100% of the world’s sustainable wood growth. Maximizing forest CO2 sequestration may not be compatible with biodiversity...

Carbon, Fossil Fuel, and Biodiversity Mitigation With Wood and Forests

The biogeochemical liabilities of grain-based crop production for bioenergy are no different from those of grain-based food production: excessive nitrate leakage, soil carbon and phosphorus loss, nitrous oxide production, and attenuated methane uptake. Contingent problems are well known, increasingly well documented, and recalcitrant: freshwater and coastal marine eutrophication, groundwater pollution, soil organic matter loss, and a warming atmosphere. The conversion of marginal lands not now farmed to annual grain production, including the repatriation of Conservation Reserve Program (CRP) and other conservation set-aside lands, will further exacerbate the biogeochemical imbalance of these landscapes, as could pressure to further simplify crop rotations. The expected emergence of biorefinery and combustion facilities that accept cellulosic materials offers an alternative outcome: agricultural landscapes that accumulate soil carbon, that conserve nitrogen and phosphorus, and that emit relatively small amounts of nitrous oxide to the atmosphere. Fields in these landscapes are planted to perennial crops that require less fertilizer, that retain sediments and nutrients that could otherwise be transported to groundwater and streams, and that accumulate carbon in both soil organic matter and roots. If mixed-species assemblages, they additionally provide biodiversity services. Biogeochemical responses of these systems fall chiefly into two areas: carbon neutrality and water and nutrient conservation. Fluxes must be measured and understood in proposed cropping systems sufficient to inform models that will predict biogeochemical behavior at field, landscape, and regional scales. Because tradeoffs are inherent to these systems, a systems approach is imperative, and because potential biofuel cropping systems and their environmental contexts are complex and cannot be exhaustively tested, modeling will be instructive. Modeling alternative biofuel cropping systems converted from different starting points, for example, suggests that converting CRP to corn ethanol production under conventional tillage results in substantially increased net greenhouse gas (GHG) emissions that can be only partly mitigated with no-till management. Alternatively, conversion of existing cropland or prairie to switchgrass production results in a net GHG sink. Outcomes and policy must be informed by science that adequately quantifies the true biogeochemical costs and advantages of alternative systems.

The biogeochemistry of bioenergy landscapes: carbon, nitrogen, and water considerations.

/pdf/wood-energy-in-america-277sq8tl7z.pdf

Wood Energy in America

Analysis of Tilting Pad Journal Bearings With Heat Transfer Effects

An approximate solution method for multilobe journal bearings that includes thermal effect is presented. The method is based on the assumption of an axial pressure distribution in the form of a polynomial, which allows the solution of Reynolds' equation by a one-dimensional finite element routine with little loss in accuracy from two-dimensional methods. A first order form of the energy equation for an adiabatic film is used to predict temperatures within the bearing, and the viscosity is determined as an exponential function of temperature. Comparison of solutions obtained by the variable viscosity method to effective viscosity solutions after Lund and Thomsen illustrates discrepancies in operating eccentricity and stiffness coefficients between the two approaches. Good correlation was obtained between the variable viscosity solutions and experimental measurements reported by Tonnesen and Hansen of eccentricity, pressures, and temperatures in a two-axial groove bearing. Presented as an American Society o...

An Approximate Solution Technique for Multilobe Journal Bearings Including Thermal Effects, with Comparison to Experiment

This paper describes the result of a study into the dynamic behavior of a magnetic bearing system. The research focuses attention on the influence of nonlinearities on the forced response of a two-degree-of-freedom rotating mass suspended by magnetic bearings and subject to rotating unbalance and feedback control. Geometric coupling between the degrees of freedom leads to a pair of nonlinear ordinary differential equations, which are then solve using both numerical simulation and approximate analytical techniques. The system exhibits a variety of interesting and somewhat unexpected phenomena including various amplitude driven bifurcational events, sensitivity to initial conditions, and the complete loss of stability associated with the escape from the potential well in which the system can be thought to be oscillating. An approximate criterion to avoid this last possibility is developed based on concepts of limiting the response of the system. The present paper may be considered as an extension to an earlier study by the same authors, which described the practical context of the work, free vibration, control aspects, and derivation of the mathematical model.

/pdf/nonlinear-behavior-of-a-magnetic-bearing-system-2oqb63o1km.pdf

J. D. Knight

Papers

Wood Energy in America

Analysis of Tilting Pad Journal Bearings With Heat Transfer Effects

An Approximate Solution Technique for Multilobe Journal Bearings Including Thermal Effects, with Comparison to Experiment

Nonlinear Behavior of a Magnetic Bearing System

Effects of Two Film Rupture Models on the Thermal Analysis of a Journal Bearing