Morphological Evolution in Air-Stable Metallic Iron Nanostructures and Their Magnetic Study

Iron nanostructures with morphology ranging from discrete nanoparticles to nearly monodisperse hierarchical nanostructures have been successfully synthesized using solvated metal atom dispersion (SMAD) method. Such a morphological evolution was realized by tuning the molar ratio of ligand to metal. Surface energy minimization in confluence with strong magnetic interactions and ligand-based stabilization results in the formation of nanospheres of iron. The as-prepared amorphous iron nanostructures exhibit remarkably high coercivity in comparison to the discrete nanoparticles and bulk counterpart. Annealing the as-prepared amorphous Fe nanostructures under anaerobic conditions affords air-stable carbon-encapsulated Fe(0) and Fe3C nanostructures with retention of the morphology. The resulting nanostructures were thoroughly analyzed by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Raman spectroscopy. TGA brought out that Fe3C nanostructures are more robust toward oxidation than those of a-Fe. Finally, detailed magnetic studies were carried out by superconducting quantum interference device (SQUID) magnetometer and it was found that the magnetic properties remain conserved even upon exposure of the annealed samples to ambient conditions for months.

Structural and Magnetic Phase Transformations of Hydroxyapatite-Magnetite Composites under Inert and Ambient Sintering Atmospheres

The present work reports the impact of sintering conditions on the phase stability in hydroxyapatite (HA) magnetite (Fe3O4) bulk composites, which were densified using either pressureless sintering in air or by rapid densification via hot pressing in inert atmosphere. In particular, the phase abundances, structural and magnetic properties of the (1-x)HA-xFe(3)O(4) (x = 5, 10, 20, and 40 wt %) composites were quantified by corroborating results obtained from Rietveld refinement of the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Mossbauer spectroscopy. Post heat treatment phase analysis revealed a major retention of Fe3O4 in argon atmosphere, while it was partially/completely oxidized to hematite (alpha-Fe2O3) in air. Mossbauer results suggest the high-temperature diffusion of Fe3+ into hydroxyapatite lattice, leading to the formation of Fe-doped HA. A preferential occupancy of Fe3+ at the Ca(1) and Ca(2) sites under hot-pressing and conventional sintering conditions, respectively, was observed. The lattice expansion in HA from Rietveld analysis correlated well with the amounts of Fe-doped HA determined from the Mossbauer spectra. Furthermore, hydroxyapatite in the monoliths and composites was delineated to exist in the monoclinic (P2(1)/b) structure as against the widely reported hexagonal (P6(3)/m) crystal lattice. The compositional similarity of iron doping in hydroxyapatite to that of tooth enamel and bone presents HA-Fe3O4 composites as potential orthopedic and dental implant materials.

EXPERIMENTAL STUDIES ON AIR-ASSISTED ATOMIZATION OF JATROPHA PURE PLANT OIL

The present study focuses on exploring air-assisted atomization strategies for effective atomization of high-viscosity biofuels, such as pure plant oils (PPOs). The first part of the study concerns application of a novel air-assisted impinging jet atomization for continuous spray applications, and the second part concerns transient spray applications. The particle/droplet imaging analysis (PDIA) technique along with direct imaging methods are used for the purpose of spray characterization. In the first part, effective atomization of Jatropha PPO is demonstrated at gas-to-liquid ratios (GLRs) on the order 0.1. The effect of liquid and gas flow rates on the spray characteristics is evaluated, and results indicate a Sauter mean diameter (SMD) of 50 mu m is achieved with GLRs as low as 0.05. In the second part of the study, a commercially available air-assisted transient atomizer is evaluated using Jatropha PPO. The effect of the pressure difference across the air injector and ambient gas pressure on liquid spray characteristics is studied. The results indicate that it is possible to achieve the same level of atomization of Jatropha as diesel fuel by operating the atomizer at a higher pressure difference. Specifically, a SMD of 44 mu m is obtained for the Jatropha oil using injection pressures of <1 MPa. A further interesting observation associated with this injector is the near constancy of a nondimensional spray penetration rate for the Jatropha oil spray.

Primary and rechargeable zinc-air batteries using ceramic and highly stable TiCN as an oxygen reduction reaction electrocatalyst

Primary and secondary zinc-air batteries based on ceramic, stable, one dimensional titanium carbonitride (TiCN) nanostructures are reported. The optimized titanium carbonitride composition by density functional theory reveals their good activity towards the oxygen reduction reaction (ORR). Electrochemical measurements show their superior performance for the ORR in alkaline media coupled with favourable kinetics. The nanostructured TiCN lends itself amenable to be used as an air cathode material in primary and rechargeable zinc-air batteries. The battery performance and cyclability are found to be good. Further, we have demonstrated a gel-based electrolyte for rechargeable zinc-air batteries based on a TiCN cathode under ambient, atmospheric conditions without any oxygen supply from a cylinder. The present cell can work at current densities of 10-20 mA cm(2) (app. 10 000 mA g(-1) of TiCN) for several hours (63 h in the case of 10 mA cm(-2)) with a charge retention of 98%. The low cost, noble metal-free, mechanically stable and corrosion resistant TiCN is a very good alternative to Pt for metal-air battery chemistry.

Characterization of Air-Water Two-Phase Vertical Flow by Using Electrical Resistance Imaging

The characterization of air-water two-phase vertical flow in a 12 m flow loop with 1.5 m of vertical section is studied by using electrical resistance tomography (ERT). By applying a fast data collection to a dual-plane ERT sensor and an iterative image reconstruction algorithm, relevant information is gathered for implementation of flow characteristics, particularly for flow regime recognition. A cross-correlation method is also used to interpret the velocity distribution of the gas phase on the cross section. The paper demonstrates that ERT can now be deployed routinely for velocity measurements and this capability will increase as faster measurement systems evolve.

Florida's ground water quality monitoring program: background hydrogeochemistry

The purpose of this report is to present the results of the initial quantification of background water quality in each of the state's major potable aquifer systems. Results are presented and interpreted in light of the influencing factors which locally and regionally affect ambient ground-water quality. This initial data will serve as a baseline from which future sampling results can be compared. Future sampling of the Network will indicate the extent to which Florida's regional ground-water resources are improving or declining in quality. (Document has 378 pages.)

Tension and Ampacity Monitoring System for Overhead Lines

Real time monitoring allows the determination of the line state and the calculation of the actual rating value. The real time monitoring systems measure sag, conductor tension, conductor temperature or weather related magnitudes. In this paper, a new ampacity monitoring system for overhead lines, based on the conductor tension, the ambient temperature, the solar radiation and the current intensity, is presented. The measurements are transmitted via GPRS to a control center where a software program calculates the ampacity value. The system takes into account the creep deformation experienced by the conductors during their lifetime and calibrates the tension-temperature reference and the maximum allowable temperature in order to obtain the ampacity. The system includes both hardware implementation and remote control software.

M/V ELPIS Coral Reef Restoration Monitoring Report Monitoring Events 2004-2007 Florida Keys National Marine Sanctuary, Monroe County, Florida

This document presents the results of the first three monitoring events to track the recovery of a repaired coral reef injured by the M/V Elpis vessel grounding incident of November 11, 1989. This grounding occurred within the boundaries of what at the time was designated the Key Largo National Marine Sanctuary (NMS), now designated the Key Largo NMS Existing Management Area within the Florida Keys National Marine Sanctuary (FKNMS). Pursuant to the National Marine Sanctuaries Act (NMSA) 16 U.S.C. 1431 et seq., and the Florida Keys National Marine Sanctuary and Protection Act (FKNMSPA) of 1990, NOAA is the federal trustee for the natural and cultural resources of the FKNMS. Under Section 312 of the NMSA, NOAA has the authority to recover monetary damages for injury, destruction, or loss of Sanctuary resources, and to use the recovered monies to restore injured or lost sanctuary resources within the FKNMS. The restoration monitoring program tracks patterns of biological recovery, determines the success of restoration measures, and assesses the resiliency to environmental and anthropogenic disturbances of the site over time. To evaluate restoration success, reference habitats adjacent to the restoration site are concurrently monitored to compare the condition of restored reef areas with natural coral reef areas unimpacted by the vessel grounding. Restoration of the site was completed September 1995, and thus far three monitoring events have occurred; one in the summer of 2004, one in the summer of 2005, and the latest in the summer of 2007. The monitoring in 2004 was in the nature of a “pilot project,” or proof of concept. Only the quantitative results of the 2005 and 2007 monitoring are presented and discussed. Monitoring has consisted of assessment of the structural stability of limestone boulders used in the restoration and comparison of the coral communities on the boulders and reference areas. Corals are divided into Gorgonians, Milleporans, and Scleractinians. Coral densities at the Restored and Reference areas for the 2005 and 2007 events are compared, and it is shown that the densities of all taxa in the Restored area are greater by 2007, though not significantly so. For the Scleractinians, number and percentage of colonies by species, as well as several common biodiversity indices are provided. The greater biodiversity of the Restored area is evidenced. Also, size-class frequency distributions for Agaricia spp. (Scleractinia) are presented. These demonstrate the approaching convergence of the Restored and Reference areas in this regard. An inter-annual comparison of densities, within both areas, for all three Orders, is presented. The most noteworthy finding was the relative consistency across time for all taxa in each area. Finally, certain anomalies regarding species settlement patterns are presented. (PDF contains 48 pages.)

M/V WELLWOOD Coral Reef Restoration Monitoring Report, Monitoring Events 2004-2006. Florida Keys National Marine Sanctuary Monroe County, Florida

This document presents the results of the first two monitoring events to track the recovery of a repaired coral reef injured by the M/V Wellwood vessel grounding incident of August 4, 1984. This grounding occurred within the boundaries of what at the time was designated the Key Largo National Marine Sanctuary (NMS), now designated the Key Largo NMS Existing Management Area within the Florida Keys National Marine Sanctuary (FKNMS). Pursuant to the National Marine Sanctuaries Act (NMSA) 16 U.S.C. 1431 et seq., and the Florida Keys National Marine Sanctuary and Protection Act (FKNMSPA) of 1990, NOAA is the federal trustee for the natural and cultural resources of the FKNMS. Under Section 312 of the NMSA, NOAA has the authority to recover monetary damages for injury, destruction, or loss of Sanctuary resources, and to use the recovered monies to restore injured or lost sanctuary resources within the FKNMS. The restoration monitoring program tracks patterns of biological recovery, determines the success of restoration measures, and assesses the resiliency to environmental and anthropogenic disturbances of the site over time. To evaluate restoration success, reference habitats adjacent to the restoration site are concurrently monitored to compare the condition of restored reef areas with “natural” coral reef areas unimpacted by the vessel grounding or other injury. Restoration of the site was completed on July 22, 2002, and thus far two monitoring events have occurred; one in the Fall of 2004, and one in the Summer/Fall of 2006. The monitoring has consisted of: assessment of the structural stability of restoration modules and comparison of the coral recruitment conditions of the modules and reference sites. Corals are divided into Gorgonians, Milleporans, and Scleractinians and (except where noted) recruits are defined as follows: Gorgonians—maximum size (height) 150 mm at first monitoring event, 270 mm at second; Milleporans—maximum size (height) 65 mm at first event, 125 mm at second; Scleractinians—maximum size (greatest diameter) 50 mm at second event (only one species was size-classed at first event, at smaller size). Recruit densities at the restored and reference areas for each event are compared, as are size-class frequency distributions. For the Scleractinians, number and percentage of recruits by species, as well as several common biodiversity indices are provided. Finally, a qualitative comparison of recruit substrate settlement preference is indicated. Generally, results indicate that restored areas are converging on reference areas, based on almost all parameters examined, with one noted exception. Further monitoring is planned and the trends are anticipated to continue; close attention will be paid to the indicated anomaly. (PDF contains 63 pages.)

Evaluating approaches and technologies for monitoring organic contaminants in the aquatic environment, Ann Arbor, MI, July 21-23, 2006: workshop proceedings

The Alliance for Coastal Technologies (ACT) convened a workshop on Evaluating Approaches and Technologies for Monitoring Organic Contaminants in the Aquatic Environment in Ann Arbor, MI on July 21-23, 2006. The primary objectives of this workshop were to: 1) identify the priority management information needs relative to organic contaminant loading; 2) explore the most appropriate approaches to estimating mass loading; and 3) evaluate the current status of the sensor technology. To meet these objectives, a mixture of leading research scientists, resource managers, and industry representatives were brought together for a focused two-day workshop. The workshop featured four plenary talks followed by breakout sessions in which arranged groups of participants where charged to respond to a series of focused discussion questions. At present, there are major concerns about the inadequacies in approaches and technologies for quantifying mass emissions and detection of organic contaminants for protecting municipal water supplies and receiving waters. Managers use estimates of land-based contaminant loadings to rivers, lakes, and oceans to assess relative risk among various contaminant sources, determine compliance with regulatory standards, and define progress in source reduction. However, accurately quantifying contaminant loading remains a major challenge. Loading occurs over a range of hydrologic conditions, requiring measurement technologies that can accommodate a broad range of ambient conditions. In addition, in situ chemical sensors that provide a means for acquiring continuous concentration measurements are still under development, particularly for organic contaminants that typically occur at low concentrations. Better approaches and strategies for estimating contaminant loading, including evaluations of both sampling design and sensor technologies, need to be identified. The following general recommendations were made in an effort to advance future organic contaminant monitoring: 1. Improve the understanding of material balance in aquatic systems and the relationship between potential surrogate measures (e.g., DOC, chlorophyll, particle size distribution) and target constituents. 2. Develop continuous real-time sensors to be used by managers as screening measures and triggers for more intensive monitoring. 3. Pursue surrogate measures and indicators of organic pollutant contamination, such as CDOM, turbidity, or non-equilibrium partitioning. 4. Develop continuous field-deployable sensors for PCBs, PAHs, pyrethroids, and emerging contaminants of concern and develop strategies that couple sampling approaches with tools that incorporate sensor synergy (i.e., measure appropriate surrogates along with the dissolved organics to allow full mass emission estimation).[PDF contains 20 pages]