Effect of tides on solute flushing from a strait: imaging flow and transport in the East River with SF6

In June 2003, two injections of approximately 3.9 mol of sulfur hexafluoride (SF6) were made 8 days apart in the East River, a 25 km tidal strait, to observe solute mixing and dissipation. The first injection occurred at slack before flood, and the second at slack before ebb (flood = northward flow). Tidally synchronized surveys of the SF6 tracer patch, supplemented by vertical profiles, were conducted by boat for 6 and 4 days following the flood and ebb injections, respectively. Residence times for the tracer-tagged water mass in the East River were estimated to be 3.3 +/- 0.7 days and 1.7 +/- 0.5 days for the flood and ebb injections, respectively, after correcting SF6 inventories for losses of SF6 from the water column by air-water gas exchange. The data indicate that the majority of East River solutes are transported to New York Harbor and that tidal mixing dominates subtidal circulation with respectto solute transport. Surveys of the adjacent lower Hudson River revealed a northward-moving, intermediate layer of East River water. Our results suggest that tidal phasing of contaminant discharges in the East River could reduce environmental impacts, by increasing flushing rates and directing a greater fraction of material away from Long Island Sound.     

Atmospheric pressure gas-phase H/D exchange of serine octamers

The recently discovered homochiral serine octamer has been a focus of interest because of its possible implications for the origin of homochirality in living systems. Electrospray ionization (ESI) and sonic spray ionization (SSI) tandem mass spectrometry have been used to generate this unusually stable magic number cluster. Several structures have been suggested for the serine octamer, based on tandem mass spectrometry, ion mobility measurements, and quantum mechanical calculations. We now report experimental hydrogen/deuterium (H/D) exchange data, which demonstrate the existence of two different structures for the serine octamer. These forms undergo exchange at significantly different rates. One form may correspond to solution-phase assembled clusters and the other to octamers formed during the ionization process. Experiments done at higher resolution confirm that the experimental observations made here apply to the serine octamer without interference from metaclusters, namely, higher order clusters (Ser(16) + 2H)(+2), etc., the (12)C isotopes of which have mass-to-charge ratios identical to the protonated octamers. H/D exchange of racemic serine shows predominantly the extensively exchanged ion population, as well as providing evidence that racemic serine generates abundant metaclusters. The evidence presented here shows that one type of serine octamer is responsible for the strong chiral effects associated with the formation of these magic number clusters. These slowly exchanging more fragile clusters are the octamers that might have played a role in homochirogenesis.     

Photolytic synthesis of methyl sterculate containing mixture from methyl stearolate and diazomethane

A method for synthesis of a mixture containing methyl sterculate is described. The presence of the cyclopropene compound was verified by Halphen Test, infrared absorption and the effect on fatty acid distribution in egg yolks produced by hens consuming the synthetic product. Journal article No. 1353 of the University of Arizona.     

Draft risk assessment of the public health impact of Escherichia coli O157:H7 in ground beef

An assessment of the risk of illness associated with Escherichia coli O157:H7 in ground beef was drafted in 2001. The exposure assessment considers farm, slaughter, and preparation factors that influence the likelihood of humans consuming ground beef servings containing E. coli O157:H7 and the number of cells in a contaminated serving. Apparent seasonal differences in prevalence of cattle infected with E. coli O157:H7 corresponded to seasonal differences in human exposure. The model predicts that on average 0.018% of servings consumed during June through September and 0.007% of servings consumed during the remainder of the year are contaminated with one or more E. coli O157:H7 cells. This exposure risk is combined with the probability of illness given exposure (i.e., dose response) to estimate a U.S. population risk of illness of nearly one illness in each 1 million (9.6 x 10(-7)) servings of ground beef consumed. Uncertainty about this risk ranges from about 0.33 illness in every 1 million ground beef servings at the 5th percentile to about two illnesses in every 1 million ground beef servings at the 95th percentile.     

Examination of the inflammatory response following implantation of titanium plates coated with phospholipids in rats

Implantation of biomaterials like titanium (Ti) causes inflammatory reactions possibly affecting implant functionality. Surface modifications could improve biocompatibility and functionality of implants. Biomembrane-derived phospholipids might be useful as implant coating due to their biomimetic properties. In vitro studies demonstrated beneficial effects for 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphoethanolamin (POPE) as coating regarding interactions with cells and bacteria. Therefore, this in vivo study aimed at examining local inflammatory reactions after implantation of POPE-coated Ti plates. Ti implants with POPE attached non-covalently or covalent via octadecylphosphonic acid (OPA), with OPA alone and uncoated controls were simultaneously implanted intramuscularly in rats for 7, 14 and 56 days. The peri-implant tissue was quantitatively analyzed by immunohistochemistry for total macrophages, tissue macrophages, T cells, antigen-presenting cells and proliferating cells. Overall, both POPE-coated series were comparable to the controls. Furthermore, no differences were found between POPE coating on a covalently linked OPA monolayer and POPE coating dried from solution. Together with earlier in vitro results, this demonstrates the potential of phospholipids for implant surface modification.     

Transport dynamics in a sheltered estuary and connecting tidal straits: SF6 tracer study in New York Harbor

In July 2002, approximately 0.9 mol of sulfur hexafluoride (SF6) was injected into Newark Bay, NJ, a 14 km2 estuary that forms part of New York Harbor, to investigate circulation, mixing, and the transport and fate of solutes. The SF6 tracer was observed over 11 consecutive days using a high-resolution measurement system. Total tracer mass in the sheltered waters declined quasiexponentially at a rate of 0.29 +/- 0.03 d(-1). Air-water gas exchange was estimated to account for 56% of tracer mass loss, upon the basis of wind speed/gas exchange parametrizations. Large-scale tidal transfer of solutes through the Kill van Kull strait (7 km long) caused net seaward flushing contrary to the apparent residual circulation. Seaward transport via the Arthur Kill strait (20 km long) appeared to depend on longitudinal dispersion, residual circulation, and freshwater discharge and was approximately 1 order of magnitude lower. The loss rate due to flushing alone was 0.13 +/- 0.02 d(-1), indicating a mean residence time for water and solutes in Newark Bay of approximately 8 days (without gas exchange). The experiment provides direct visualization of the transport of a released contaminant, and suggests a relationship between the length and configuration of tidal straits and related transport of solutes.     

Fe-Zeolite as on-Site Regenerable Adsorber for Chlorohydrocarbons in Groundwater – from Laboratory to Pilot Test

This study describes the design and upscaling of an on-site regenerable adsorbent fixed bed of Fe-loaded MFI zeolite for removal of chlorinated hydrocarbons (CHCs) from contaminated groundwater from laboratory studies to pilot scale. The zeolite has an excellent adsorption performance for the hydrophilic CHCs and can be regenerated on-site by flushing with H₂O₂ to degrade adsorbed contaminants by a catalytic Fenton-like reaction. In the pilot test, the Fe-zeolite (30 kg) maintained its performance over treatment of 1470 m³ of groundwater in 12 adsorption/regeneration cycles.