Richard N. Biagioni

Monovalent K, Cs, Tl, and Ag nitrosodicyanomethanides: completely different 3D networks with useful properties of luminescent materials and nonelectric sensors for gases.

Four K, Cs, Ag(I), and Tl(I) compounds with a nitrosodicyanomethanide ONC(CN)(2)(-) anion have been obtained and characterized using IR spectroscopy; UV-visible spectroscopy; room temperature, solid-state photoluminescence; and solutions electrical conductivity measurements. Cesium and thallium(I) complexes were obtained for the first time, and crystal structures were determined for Cs{ONC(CN)(2)}, Ag{ONC(CN)(2)}, and Tl{ONC(CN)(2)}. These structures indicate the formation of completely different 3D polymeric networks in which the anion acts as a bridging ligand of different capacity. The cyanoxime ligand in all complexes studied is in the nitroso form and adopts a planar configuration. The structure of the cesium salt is ionic. The structure of Ag{ONC(CN)(2)} represents a 3D coordination polymer where the anion acts as a tetradentate ligand with all four bonds between Ag(I) and donor atoms (three N and one O) significantly shorter than the sum of the ionic radii for these elements. The silver(I) atom in this compound has a distorted tetrahedral surrounding. Additionally, Ag{ONC(CN)(2)} is remarkably UV- and visible-light-insensitive. However, after exposure of the solid complex to gases such as H(2), CO, NO, C(2)H(2), and C(2)H(4), the surface of the compound becomes visible-light-sensitive and changes color with significant darkening, which indicates reduction of the metal. This is reflected in a dramatic decrease of intensity of the photoluminescence of Ag[ONC(CN)(2)] in the presence of these gases, which might be utilized for nonelectric sensor applications. The Tl[ONC(CN)(2)] complex represents a transitional species between ionic (Cs) and covalent (Ag) compounds. The thallium(I) center has four shorter bonds than the sum of the ionic radii bonds (three with N and one with O atoms) and three longer electrostatic (ionic) contacts with the anion. The 6s(2) lone pair is stereoactive, and the coordination polyhedron is best described as a distorted square pyramid. Room temperature diffusion reflectance spectra of solid K{ONC(CN)(2)}, Ag{ONC(CN)(2)}, and Tl{ONC(CN)(2)} demonstrated a bathochromic shift of the bands lambda(max) depending on the atomic number of the metal center, indicating a significant role of metal centers in electronic transitions in these compounds. This phenomenon was observed for the first time. The latter complex at 293 K exhibited structured metal-based red photoluminescence in the range of 690-800 nm that depends on the excitation wavelengths.

Relationship between soil lead and airborne lead concentrations at Springfield, Missouri, USA

This study tests whether lead deposited to soil from automobiles during past years in a medium-sized US city (population 150,000) may present a current health risk. It examines the relationship between current soil lead concentrations at nine locations within the city of Springfield, Missouri, and airborne lead levels measured at the same locations during years (1975-1981) when lead emissions from automobiles were much greater than at present. A strong, significant correlation is found between soil and airborne lead levels at eight of the sites (r = 0.91, P < 0.005 for soil lead vs. 1979 airborne lead), in low-traffic areas as well as in areas adjacent to heavy traffic flow. Residual lead concentrations in these soils are relatively low, even for the high-traffic sites, as expected for a medium sized city.

System and method for assessing breathing and vocal tract sound production of a user

A system and method for assessing breathing and vocal tract sound production of a user. The system comprises a first sensor generating a vocal tract sound signal representing vocal tract sounds produced by the user, a second sensor generating a breathing signal representing breathing movement of the user, and a signal processing unit for processing the vocal tract sound and breathing signals. The method comprises the steps of sensing vocal tract sounds produced by the user and providing a vocal tract sound signal representative thereof, sensing breathing movement of the user and providing a breathing signal representative thereof, receiving the signals via an analog input for processing the signals, generating a combined signal by superimposing the vocal tract sound and breathing signals, and displaying the combined signal to the user.

Synthesis of (η6-C13H10)Mn(CO)2LPF6 and (η6-C13Hg9)Mn(CO)2L complexes (L = phosphines and phosphites) and kinetic studies of η6 to η5 ring slippage reactions

Abstract This report describes the syntheses and characterizations of (η 6 -C 13 H 10 )Mn(CO) 2 LPF 6 and (η 6 -C 13 H 9 )Mn(CO) 2 L complexes (L = P(OEt) 3 , PPh 3 , PEt 3 , and η 1 -(diphos) (diphos = 1,2-bis(diphenylphosphino)ethane), and kinetic studies of (η 6 -C 13 H 9 )Mn(CO),L→(η 5 -C 13 H 9 )Mn(CO) 2 L ring slippage reactions. Δ H ‡ values for the η 6 → η 5 slippage reactions of the P(OEt) 3 (26.4 kcal/mol), PPh 3 (23.1 kcal mol −1 ), and PEt 3 (25.6 kcal/mol −1 ) complexes are similar to values previously reported for CO and P(n-Bu) 3 complexes. The unusually low value of Δ H ‡ = 19.9 kcal/mol for the η 1 -diphos complex is attributed to an intermediate stabilized by an intramolecular nucleophilic attack of the free end of the diphos ligand on the metal center.

An overview of nitrate sources and operating processes in arid and semiarid aquifer systems

Nitrate concentration in most aquifers in arid and semi-arid areas has increased in the past several decades as a result of human activities. Under the predominantly oxic conditions of these aquifers, denitrification is inhibited, allowing nitrate, a soluble and stable form of nitrogen (N), to accumulate. Because of its close association with municipal and agricultural wastes, nitrate is commonly used as an indicator of anthropogenic contamination. Aquifers affected by agricultural waste may contain salts from irrigation returns and herbicides in addition to nitrates. Preventing leakage from soil to deeper parts of the aquifer is thus a priority in the sustainable management of aquifers in arid and semiarid areas. Studies report a wide range of nitrate concentrations distributed non-uniformly within the aquifer, with roughly 40% and 20% of sampled wells exceeding 50mg/L nitrate in shallow and deep parts of the aquifer respectively. In aquifers at risk of becoming contaminated, nitrate isotopes (δ15N, δ18O, Δ17O) can be used to identify the source of nitrogen as mineral or organic fertilizer, sewage, or atmospheric deposition. A variety of mathematical models (crop, hydrological, geochemical, or a combination of them) have been successful in identifying best practices that minimize N leakage without negatively affecting crop yield. In addition, field research in crop management, e.g., conservation agriculture, has yielded promising results in determining the adequate dosage and time of application of fertilizers to reduce N losses. Examples of key dryland aquifers impacted by nitrate are discussed, and some of the most pressing challenges to achieve sustainability are presented.

Monitoring and Numerical Modeling of Shallow CO{sub 2} Injection, Greene County, Missouri

The project titled Monitoring and Numerical Modeling of Shallow CO{sub 2} Injection, Greene County, Missouri provided training for three graduate students in areas related to carbon capture and storage. Numerical modeling of CO{sub 2} injection into the St. Francois aquifer at the Southwest Power Plant Site in Greene County, Missouri indicates that up to 4.1 x 10{sup 5} metric tons of CO{sub 2} per year could be injected for 30 years without exceeding a 3 MPa differential injection pressure. The injected CO{sub 2} would remain sequestered below the top of the overlying caprock (St. Francois confining unit) for more than 1000 years. Geochemical modeling indicates that portions of the injected CO{sub 2} will react rapidly with trace minerals in the aquifer to form various solid carbonate mineral phases. These minerals would store significant portions of injected CO{sub 2} over geologic time scales. Finally, a GIS data base on the pore-fluid chemistry of the overlying aquifer system in Missouri, the Ozark aquifer, was compiled from many sources. This data base could become useful in monitoring for leakage from future CO{sub 2} sequestration sites.

222Rn emanation from uranium-glazed ceramics

Orange-red uranium-glazed dinnerware was found to emanate 222Rn to produce an average of less than 0.1 Bq 222Rn decay per piece, which should have no associated health risks. Comparison of 222Rn emanation to 226Ra in glazes (measured by alpha spectrometry) indicated inefficient emanation (<5%) of 222Rn, consistent with the low radon levels observed and with the presence of 222Rn progeny in glazes. These studies also showed that reagent grade uranium compounds may emanate measurable 222Rn.