Impact of Biofuel Blends on Black Carbon Emissions from a Gas Turbine Engine.

Presented here is an overview of non-volatile particulate matter (nvPM) emissions, i.e. "soot" as assessed by TEM analyses of samples collected after the exhaust of a J-85 turbojet fueled with Jet-A as well as with blends of Jet-A and Camelina biofuel. A unifying explanation is provided to illustrate the combustion dynamics of biofuel and Jet-A fuel. The variation of primary particle size, aggregate size and nanostructure are analyzed as a function of biofuel blend across a range of engine thrust levels. The postulate is based on where fuels start along the soot formation pathway. Increasing biofuel content lowers aromatic concentration while placing increasing dependence upon fuel pyrolysis reactions to form the requisite concentration of aromatics for particle inception and growth. The required "kinetic" time for pyrolysis reactions to produce benzene and multi-ring PAHs allows increased fuel-air mixing by turbulence, diluting the fuel-rich soot-forming regions, effectively lowering their equivalence ratio. With a lower precursor concentration, particle inception is slowed, the resulting concentration of primary particles is lowered and smaller aggregates were measured. The lower equivalence ratio also results in smaller primary particles because of the lower concentration of growth species.

Temporal trends in the relative cost of dying: evidence from Canada.

OBJECTIVE: To measure change over time in the relationship between health care expenditures for individuals that die in a given year and age matched survivors. METHODS: Administrative data covered government-funded hospital, physician, prescription drug, and continuing care services for the entire population aged 65 and over in the province of British Columbia between 1991 and 2001. Individuals were separated according to age group and decedent/survivor status. The average utilization cost was estimated for each age group and survivor status in each year from 1991 to 2001. Time trends in decedent and survivor costs, and the ratio between the two, were analyzed for each service category. RESULTS: Inflation-adjusted decedent costs rose by almost 10% between 1991 and 2001, while survivor costs fell slightly. The ratio of decedent to survivor costs increased for all age groups, and was greatest for hospital and continuing care costs. Although the study population mortality rate fell over the study period, the proportion of health care costs allocated to decedents grew by 8%. CONCLUSIONS: If mortality rates continue to fall, lower survivor costs and higher decedent costs will lower future growth in health expenditures due to aging.

Counting backward to health care's future: using time-to-death modeling to identify changes in end-of-life morbidity and the impact of aging on health care expenditures.

In most developed countries, as the largest population cohorts approach the age of sixty-five, the impact of population aging on health care expenditures has become a topic of growing interest. This articles examines trends in elderly disability and end-of-life morbidity, estimations of the cost of dying, and models of expenditures as a function of both age and time-to-death and finds broad improvement in mortality and morbidity among the elderly in the developed world. Reduced mortality and low growth in the costs associated with dying could reduce forecasted expenditures, but high growth in expenditures for those not close to death and for nonhospital services could create new economic pressures on health care systems.

Evaluation and comparison of portable emissions measurement systems and federal reference methods for emissions from a back-up generator and a diesel truck operated on a chassis dynamometer.

There is considerable interest in portable emissions measurement systems (PEMS) for emission inventory and regulatory applications. For this study, four commercial PEMS were compared with a Federal Reference Method (FRM) for measuring emissions from a back-up generator (BUG) over steady-state loads and a diesel truck on transient and steady-state chassis dynamometer tests. The agreement between the PEMS and the FRM varied depending on the pollutant and the particular PEMS tested for both the BUG and chassis dynamometer testing. The best performing PEMS for both the BUG and chassis testing was within approximately 12% for NOx of the FRM. For the BUG testing, several PEMS showed agreement with the FRM within approximately 5% for CO2. For the chassis dynamometer testing, the best PEMS showed agreement typically within approximately 5% for CO2. PM measurements for the BUG testing were low compared to the FRM, with the best measurements approximately 20% lower. For the chassis testing, two PM PEMS showed a good correlation but a high bias, while the correlation was worse for the other two PEMS. For each emissions component, some PEMS under different test conditions showed considerably larger deviations than those for the best performing PEMS.