Aqueous matrix compositions and pH influence feline calicivirus inactivation by high pressure processing

The individual effects of pH (pH 3 to 8), NaCl (0 to 21%), sucrose (0 to 70%), and whey protein (0 to 2%) on pressure resistance of feline calicivirus (FCV) in Dulbecco's modified Eagle medium with 10% fetal bovine serum were determined. At pH 3 through 8, the virus was more resistant to pressure at a pH of < or = 5.2. For FCV samples with sucrose (up to 40%) or NaCl (up to 12%), the amount of FCV inactivated by pressure was inversely proportional to the sucrose or NaCl concentration. For example, a treatment of 250 MPa at 20 degrees C for 5 min reduced the FCV titer by 5.1 log PFU/ml without added sucrose and by 0.9 log PFU/ml with 40% sucrose. Reduced pressure sensitivity with increasing NaCl and sucrose concentrations was not a simple function of water activity. Different PFU reductions were observed for NaCl and sucrose samples with equivalent water activity. When protein at concentrations up to 2% did not provide a protective effect. The combined effect of NaCl and sucrose at 4 and 20 degrees C on pressure resistance of FCV also was examined. When both NaCl and sucrose were added to the FCV stock, they had an additive effect on increasing the pressure resistance of FCV. The individual (6% NaCl or 20% sucrose) and combined (6% NaCl plus 20% sucrose) resistance effects did not abrogate enhanced inactivation for pressure treatments at 4 degrees C compared with those at 20 degrees C. Aqueous matrix compositions, in particular different concentrations of NaCl and sucrose or different pH values, can substantially alter the efficiency of virus inactivation by high pressure processing.     

Apportionment of primary and secondary organic aerosols in southern California during the 2005 study of organic aerosols in riverside (SOAR-1)

Ambient sampling was conducted in Riverside, California during the 2005 Study of Organic Aerosols in Riverside to characterize the composition and sources of organic aerosol using a variety of state-of-the-art instrumentation and source apportionmenttechniques. The secondary organic aerosol (SOA) mass is estimated by elemental carbon and carbon monoxide tracer methods, water soluble organic carbon content, chemical mass balance of organic molecular markers, and positive matrix factorization of high-resolution aerosol mass spectrometer data. Estimates obtained from each ofthese methods indicate that the organic fraction in ambient aerosol is overwhelmingly secondary in nature during a period of several weeks with moderate ozone concentrations and that SOA is the single largest component of PM1 aerosol in Riverside. Average SOA/OA contributions of 70-90% were observed during midday periods, whereas minimum SOA contributions of approximately 45% were observed during peak morning traffic periods. These results are contraryto previous estimates of SOAthroughout the Los Angeles Basin which reported that, other than during severe photochemical smog episodes, SOA was lower than primary OA. Possible reasons for these differences are discussed.     

Rheological Characterization of Nitrocellulose Gels

Various nitrocellulose, NC, based propellant formulations need to be processed using new and more environmentally friendly solvent combinations on the one hand and using continuous processing methodologies on the other hand. A detailed understanding of the significant changes that take place in the structure and hence the rheological behavior of NC based formulations during manufacture is required to minimize the use of organic solvents and to revert to safer and green solvents. Towards achieving these objectives, experimental methodologies were developed for the first time to enable the accurate characterization and thus fingerprinting of the rheological behavior of NC gels. In these methodologies linear viscoelastic measurements are employed. The concentration of the solvents existing in the gel sample during rheological characterization is concomitantly monitored to allow the documentation of the major source of error associated with the rapid loss of the typical solvents, which generally exhibit relatively high vapor pressures. These measurements have indicated that the source of the NC fibers and the treatment method alter the rheological behavior and can be tracked. The rheological properties of the NC gels can be linked to their manufacturability and such data can be used to pinpoint optimum geometries and processing conditions. The processability of the NC based formulations can also be tailored on the basis of rheological characterization, allowing the manufacturers greater latitude for reducing costs and environmental footprint during manufacture, as well as improving the quality of their NC based energetic formulations.     

CHARACTERIZATION OF OIL SANDS MINERAL COMPONENTS AND CLAY-ORGANIC COMPLEXES

ABSTRACT

Differences in oil sands processability and extraction yields can be dependent upon many factors including the composition of the mineral components and the organic complexes that are associated with certain minerals. These mineral-organic associations help provide the bridge which leads to carry over of bitumen with the tailings as well as carry over of water and mineral matter with the product. The nature of the organic component of clay-organic complexes extracted from various streams in an oil sands recovery process is discussed in relation to the stability of both water-in-oil and oil-in-water emulsions formed. These samples have been studied with nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) as veil as with other techniques such as interfacial tension measurements.     

Hydrogen production through methane–steam cyclic redox processes with iron-based metal oxides

The redox performance of pure iron oxide (Fe₂O₃) and iron oxide modified with ceria (CeO₂) and/or zirconia (ZrO₂) as an oxygen carrier was investigated for hydrogen (H₂) production through a methane-steam redox process. The addition of both CeO₂ and ZrO₂ were found to be a more effective modification of Fe₂O₃ than the addition CeO₂ or ZrO₂ alone. It was found that the reducibility of Fe₂O₃ was enhanced by CeO₂ and the thermal stability of Fe₂O₃ was improved by ZrO₂. These results, therefore, led to the conclusion of the synergistic effect in the Fe₂O₃-CeO₂-ZrO₂ mixed oxide. As a result, both the redox activity and the thermal stability were significantly improved, and increases in H₂ yield and purity could be maintained by the modification. The redox temperature was found to have a significant effect on redox performance. The production of H₂ was considerably improved when the redox temperature was increased from 650 to 750 °C. The ZrO₂ concentration in Fe₂O₃-CeO₂-ZrO₂ mixed oxide samples was also found to influence performance with the highest H₂ yield observed at a ZrO₂ concentration of 75 wt.%. Although all materials tested showed a reduction in surface area in the first redox cycle, the change in surface area in subsequent cycles was found to be smaller and the yield of H₂ could be maintained at a constant level over a longer period for the mixed oxide containing 75 wt.% ZrO₂.     

Synergy of elemental Fe and Ti promoting low temperature hydrogen sorption cycling of magnesium

We studied the catalytic effects of Titanium, Iron and FeTi intermetallic on the desorption kinetics of magnesium hydride. In order to separate the catalytic effects of each element from additional synergistic and alloying effects, Mg-Ti and Mg-Fe mixtures were studied as a baseline for Mg-Fe-Ti elemental and Mg-(FeTi) intermetallic composites. Sub-micron dimensions for MgH₂ particles and excellent nanoscale catalyst dispersion was achieved by high-energy ball-milling as confirmed by analytical electron microscopy techniques. The composites containing Fe shows desorption temperature of 170 K lower than as-received MgH₂ powder, which makes it suitable to be cycled at relatively low temperature of 523 K. Furthermore, the low cycling temperature prevents the formation of Mg₂FeH₆. In sorption cycling tests, Mg-10% Ti and Mg-10% (FeTi), after about 5 activation cycles, show fast desorption kinetics initially, but the kinetics also degrade faster than for all other composites, eventually slowing down by a factor of 7 and 4, respectively. The ternary Mg-Fe-Ti composite shows best performance. With the highest BET surface area of 40 m²/g, it also shows much less degradation during cycling. This is attributed to titanium hydride acting as a size control agent preventing agglomeration of particles; while Fe works as a very strong catalyst with uniform and nanoscale dispersion on the surface of MgH₂ particles.     

A new modeling approach of pressure waves at the inlet of internal combustion engines

This paper presents a new model used to describe the propagation of pressure waves at the inlet systems of internal combustion engine. In the first part, an analogy is made between the compressible air in a pipe and a mechanical ideal mass damper spring system. A new model is then presented and the parameters of this model are determined by the use of an experimental setup (shock tube test bench). With this model, a transfer function is defined in order to link directly the pressure and the air mass flow rate. In the second part, the model is included into an internal combustion engine simulation code. The results obtained with this code are compared to experimental ones which are measured on a one-cylinder engine test bench. This last one is driven by an electric motor in order to study only the effect of the pressure waves on the engine behavior. A good agreement is obtained between the experimental results and the numerical ones and the new approach is an alternative method for modeling the pressure wave phenomena in an internal combustion engine manifold.     

Introduction to the Asian Energy Security project: Project organization and methodologies

The spectacular recent economic growth in the Asia-Pacific region in general, and in many of the economies of Northeast Asia in particular, has spurred a vast expansion in the need for energy services, and an expansion in the demand for the fuels that help to supply these services. Future projections suggest that the growth of fossil fuel use in Northeast Asia, especially in China, will have major consequences for financial and fuel markets and pollution both regionally and globally. Before the project described in this paper was initiated, there was no ongoing forum for energy experts from all of the countries of the region to meet, informally and in an unofficial capacity, to discuss openly and in a targeted fashion the energy situations in their countries, and to work together to evaluate the energy efficiency costs and benefits of different ways of meeting regional demand. The Asian Energy Security (AES) project provides such a forum, and as such constitutes a unique resource in the engagement of the countries of Northeast Asia on the topic of energy security.     

Energy security and sustainability in Northeast Asia

“Energy Security” has typically, to those involved in making energy policy, meant mostly securing access to oil and other fossil fuels. With increasingly global, diverse energy markets, however, and increasingly transnational problems resulting from energy transformation and use, old energy security rationales are less salient, and other issues, including climate change and other environmental, economic, and international considerations are becoming increasingly important. As a consequence, a more comprehensive operating definition of “Energy Security” is needed, along with a workable framework for analysis of which future energy paths or scenarios are likely to yield greater Energy Security in a broader, more comprehensive sense. Work done as a part of the Nautilus Institute's “Pacific Asia Regional Energy Security” (PARES) project developed a broader definition of Energy Security, and described an analytical framework designed to help to compare the energy security characteristics – both positive and negative – of different quantitative energy paths as developed using software tools such as the LEAP (Long-range Energy Alternatives Planning) system.     

Implications of local lifecycle analyses and low carbon fuel standard design on gasohol transportation fuels

State and regional policies, such as low carbon fuel standards (LCFSs), increasingly mandate that transportation fuels be examined according to their greenhouse gas (GHG) emissions. We investigate whether such policies benefit from determining fuel carbon intensities (FCIs) locally to account for variations in fuel production and to stimulate improvements in FCI. In this study, we examine the FCI of transportation fuels on a lifecycle basis within a specific state, Minnesota, and compare the results to FCIs using national averages. Using data compiled from 18 refineries over an 11-year period, we find that ethanol production is highly variable, resulting in a 42% difference between carbon intensities. Historical data suggests that lower FCIs are possible through incremental improvements in refining efficiency and the use of biomass for processing heat. Stochastic modeling of the corn ethanol FCI shows that gains in certainty due to knowledge of specific refinery inputs are overwhelmed by uncertainty in parameters external to the refiner, including impacts of fertilization and land use change. The LCA results are incorporated into multiple policy scenarios to demonstrate the effect of policy configurations on the use of alternative fuels. These results provide a contrast between volumetric mandates and LCFSs.