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The objective of this project was to examine the ability of a small system to meet new corrosion control operational guidelines in Canada. This study was conducted in three parallel program areas: (a) use of community volunteers, (b) sampling at controlled municipal buildings, and (c) conducting a pilot-scale program. The study site was a community with an approximate population of 7000. The water quality of the treated water had a low alkalinity ( Key words: lead, corrosion control, polyphosphate, orthophosphate, premise plumbing. Ce projet avait comme objectif d'examiner la capacite d'un petit systeme a rencontrer les nouvelles lignes directives operationnelles de protection contre la corrosion au Canada. La presente etude a ete realisee dans trois domaines de programme paralleles : (a) utilisation de benevoles de la communaute, (b) echantillonnage des immeubles municipaux controles et (c) realisation d'un programme en usine-pilote. Le site de l'etude etait une communaute comptant une population d'environ 7000 personnes. La qualite de l'eau traitee presentait une faible alcalinite ( Mots-cles : plomb, prevention de la corrosion, polyphosphate, phosphate, plomberie de residence. [Traduit par la Redaction], Introduction Maintaining an active corrosion control program is critical for managing red water concerns and associated aesthetic parameters (e.g., McNeill and Edwards 2001; Maddison et al. 2001) and for minimizing [...]

Here we present direct observation of a quantum reactivity with respect to the amounts of [O.sub.2] adsorbed and the rates of surface oxidation as a function of film thickness on ultrathin (2-6 nm) Pb mesas by scanning tunneling microscopy. Simultaneous spectroscopic measurements on the electronic structures reveal a quantum oscillation that originates from quantum well states of the mesas, as a generalization of the Fabry--Perot modes of confined electron waves. We expect the quantum reactivity to be a general phenomenon for most ultrathin metal films with broad implications, such as nanostructure tuning of surface reactivities and rational design of heterogeneous catalysts. Pb(111) | quantum size effects | scanning tunneling microscopy | surface reactivity

Abstract -- The possibility of using solid-electrolyte transducers with nonstoichiometric electrodes was studied, and the effect of the material and nonstoichiometry of lead monochalkogenides as measurement electrodes on the work [...]

The synthesis and IR structural investigations of the novel compounds PbCl2.(SCH2CH2NH3), Pb(SCH2CH2NH2)(sub 2).2PbCl(SCH2CH2NH2), and Pb(SCH2CH2NH2)(sub 2) are reported. The ab initio quantum chemical calculations show that the Pb-N bonds are based on a sigma-type n(N)-6p(Pb) interaction, which dominates the pi-type n(sub p)(S)-6p(Pb) interaction and hence determines the molecular conformation.

Byline: A. V. Parchaikin (1), E. F. Radaev (1) Abstract: The concentrations of cadmium, lead, and copper in the water of Amur Bay were determined by anodic stripping voltammetry, and the speciation of these elements in the seawater was calculated. The predominant complexes of cadmium, lead, and copper were determined in the seawater by ion exchange under dynamic conditions. The concentrations of anionic, cationic, and neutral complexes of cadmium, lead, and copper in the seawater were calculated. The ability of seawater components to form complexes with these trace elements was assessed. Author Affiliation: (1) Department of Chemistry, Far East State University, ul. Oktyabr'skaya 27, Vladivostok, 690950, Russia Article History: Registration Date: 06/10/2004

The mechanisms involved in the polarization switching process in soft and hard Pb(Zr53, Ti47)O3 (PZT) bulk ceramics were investigated through the dependency of hysteresis loop on the frequency. The results revealed a strong influence of the kind of defects and their distribution in the ferroelectric matrix on the domain switching dynamics, reflected in the frequency dependence of the coercive field and thDe percentage of back switching.

Is this study it is seen that single-crystal PZN-PT exhibits a stretched exponential type relaxation in the time domain at room temperature. Further work needs to be done to clarify the relation between the polarization relaxation kinetics and differences in the domain structures to clarify the impact of kinetics on the fatigue process.

Byline: Ufuk Celik (1), Sukran Cakli (1), Jorg Oehlenschlager (2) Keywords: Lead; Cadmium; Voltammetry; Plasma asher; Fish Abstract: Lead (Pb) and cadmium (Cd) contents in the edible parts (muscle, fillet) of 68 commercially used fish species from two European regions, the northeastern Atlantic (Tampen, north of the Shetland Islands, Faroe Islands and Copinsay) and the Mediterranean (Izmir Outer Bay, Homa Lagoon/Izmir and Mersin Bay), were determined by means of differential pulse stripping anodic voltammetry. In the sample preparation step, all frozen fish samples were lyophilised, milled in a ball mill and finally decomposed in an oxygen plasma ashing chamber. Among the fishes from northeastern Atlantic waters, the highest average Pb concentration belonged to those from Tampen with 11.25 Aug/kg and the average Cd concentration to fish from Copinsay with 2.23 Aug/kg. For the Mediterranean fishes, the highest average Pb and Cd concentrations belonged to those from Mersin Bay, with 185.39 Aug/kg and 2.12 Aug/kg, respectively. The accuracy of the concentrations determined in this study was checked by measurements of the certified reference material CRM No 422 cod muscle from the Commission of the European Communities, Community Bureau of Reference. All Cd and Pb concentrations observed in species of the eastern Mediterranean and the northeastern Atlantic were below the maximum permitted national Turkish and European levels. Author Affiliation: (1) Faculty of Fisheries, Ege University, 35100 Bornova, Izmir, Turkey (2) Institute of Fishery Technology and Fish Quality, Federal Research Centre for Fisheries, Palmaille 9, 22767, Hamburg, Germany Article History: Registration Date: 19/11/2003 Received Date: 05/08/2003 Online Date: 12/12/2003

The objectives of this work were to evaluate the effects of different parameters (Pb concentration, solution pH, Ca/Mg/Na/K salt concentrations) on Pb uptake by cocoa shells and to study the mechanisms of Pb removal in very acidic conditions. Sorption tests were conducted in shaken flasks with synthetic Pb solutions and 15 g/L cocoa shells. A lead uptake value of 161 mmol/kg was measured during the assay with [[Pb].sub.i] = 3.66 mmol/L in solution at p[H.sub.i] = 2.0 and T= 22[degrees]C. Results show that Pb uptake is very similar (14.5-16.0 mmol/kg) for an initial pH between 2.0 and 4.0, but a moderate decrease (10.8 mmol/kg) occurred when the initial pH=1.5 and the [[Pb].sub.i] = 0.25 mmol/L. High Ca and Mg concentrations (2.35 mol/L) in solution induced a significant decrease in Pb removal by cocoa shells, whereas high K and Na concentrations did not affect Pb uptake by this sorbent. This suggests that Pb uptake by cocoa shells is controlled by ion-exchange reactions with Ca/Mg ions and protons. Finally, chemical tests have shown that carboxyl and amine functional groups play a dominant role in Pb uptake by cocoa shells. DOI: 10.1061/(ASCE)0733-9372(2003)129:8(693) CE Database subject headings: Lead; Abatement and removal; Shells; Metals; Effluents.

ABSTRACT This paper discusses the application of a novel polyacrylate-based ion-exchange material for the removal of Pb ions from water. Preliminary testing includes the establishment of the operating pH range, [...]

Byline: I. Bockelmann (1), E. A. Pfister (1) Abstract: A method for subclinical diagnosis of the consequences of exposure to lead with an example of heart rate analysis is substantiated, and methods for the study of neurotoxic effects on the autonomic nervous system are critically evaluated. Author Affiliation: (1) Institut fur Arbeitsmedizin und Hygiene, Otto-von-Guericke-Universitet Magdeburg, Germany Article History: Registration Date: 16/10/2004

Full structure analyses were undertaken using time-resolved synchronton X-ray powder diffraction and neutron powder diffraction data collected on Pb- and Cd-exchanged RHO to provide information on the structural changes observed in zeolite RHO. Further the results of the temperature, atmosphere and gas loading combined in situ synchronton X-ray and neutron powder diffraction study is reported.

Remediation strategies which target reducing the solubility and toxicity of lead (Pb(II)) are being developed because of environmental worries over Pb(II) contamination in aquatic settings, soils and sediments. This study used kinetic, thermodynamic and spectroscopic investigations to evaluate the reactivity of lead (Pb(II)) on naturally occurring manganese (Mn(III,IV)) (oxyhydr)oxide minerals. The results from the study have a major impact on Pn partitioning in soil environments containing solid-phase Mn(III,IV) (oxyhdr)oxides.

The heats of adsorption of Pb on a MgO(100) film is calorimetrically measured as a function of coverage at 190K by using a removable pyroelectric polyme ribbon as the heat-detecting element. The heat of absorption grows much more slowly with coverage toward the bulk heat of sublimation, consistent with a larger Pb island density at low temperature.

Lead zinc niobate was studied to determine translational and orientational order, using optical and Raman measurements.

Researchers from Dartmouth College, NH, investigated the bioaccumulation of arsenic and lead from water samples collected from the Aberjona Watershed in Upper Mystic Lake, MA.

Researchers from the University of California, Davis suggested the evidence of historical deposition of atmospheric lead and mercury in Lake Tahoe.

Research into four reactions of ground state lead atoms in a high-temperature fast-flow reactor is presented. It was established that the Pb/O2 system seems to be dominated by heterogeneous processes.

Antimony (Sb) doping and its effects on the luminescence of lead tungstate single crystals were investigated.

An X-bran spectrometer was used to study the electron paramagnetic resonance of Eu2+ ions in a lead tungstate single crystal.

The structure of the binary lead phosphate glasses has been investigated. The use of the double quantum NMR is discussed.

Research is presented demonstrating evidence of a bimolecular dehydration reaction, which is promoted when N is smaller or equal than 3, by observing the mass spectra of mixed methanol/lead cluster ions.

Research was conducted to examine Pb2+ binding to structural zinc-binding domains determined directly by monitoring lead-thiolate charge-transfer bands. It was shown that lead-thiolate charge-transfer bands can be used to monitor lead binding to cysteine-rich sites in protein and that the use of the technique can determine the thermodynamics of lead binding to a series of structural zinc-binding domains. Results demonstrate that Pb2+ should be able to compete effectively with Zn2+ for Cys4 sites under physiological conditions.

A study was conducted to analyze the sonochemical reactions of lead tetracarboxylates with styrene. The experiments were performed in the dark under an argon atmosphere. Potassium acetate and proponaote were dried before use. Experimental results indicated that carboxylate anions significantly affects the reaction associated with the conversion of styrene. Findings also showed a sonochemical effect in homogeneous solutions.

The diffusion of the implanted radium and lead in the gallium arsenide (GaAs) semiconductor wafers was investigated through the alpha-particle energy degradation method. The alpha-particle spectra were determined using a standard silicon detector, support electronics and analysis software. It was revealed that in the GaAs wafers, the group IV elements such as tin and lead diffused through vacancies of either arsenic or gallium sites and that there was no shift in the average energy and activity of radium.

Simultaneous speciation of lead, mercury, and selenium was carried out by capillary electrophoresis. The method used a polyaminocarboxylic acid, triethylenetetraminehexaacetic acid (TTHA), as an off-column complexing agent to form UV-absorbing complexes with the analytes for direct UV detection. TTHA was also added to the background electrolyte for the on-column complexations of the analytes, as well as for improving resolution and detection. To describe the migration behavior of the complexes, a theoretical model, considerating pH value and the concentrations of TTHA and SDS, was proposed. The parameters in the model were calculated on the basis of the experimental data, by nonlinear regression. The results were in good agreement with those from the literature. The model can be used for the prediction of migration behavior and for the optimization of the separation conditions. Field-amplified stacking injection was performed because the complexes were charged. Up to 1500-fold on-line enrichment and down to sub-nanogram-per-milliliter detection limits were obtained for the analytes under the optimal stacking conditions. Finally, the applicability of the method was evaluated on seawater samples.

The dry deposition fluxes and atmospheric size distributions of anthropogenic metals such as Pb, Cu and Zn were investigated in southern Lake Michigan. The investigation was part of the Atmospheric Exchange Over Lakes and Oceans Study, which sought to determine the effects of coastal urban atmosphere contaminated with hazardous air pollutants on atmospheric deposition to adjacent Great Lakes. Results revealed that the flux of Pb, Cu, and Zn were significantly higher in Chicago than both South Haven and Lake Michigan.

The mobilization and movement of Cd and Pb from a polluted soil are examined with both experimental column percolations of ethylenediaminetetraacetic acid (EDTA) and mathematical modeling. Results reveal that only a few pulse injection experiments are required to understand the transport and complexation and solubilization processes. The simple transport model has removed the need to determine the chelate concentration at the outlet of the column to obtain the complexation rate over long elution times.

The extended X-ray absorption fine structure (EXAFS) spectroscopy proves useful in determining the binding mechanisms of Zn and Pb to Penicillium chrysogenum cell walls. Results revealed that Zn and Pb bind to the predominant phosphoryl and minor carboxyl groups with a reversed affinity. The differences in Pb and Zn isotherms can be explained by the difference in complexation affinity by reactive PO4 and COOH groups seen through EXAFS spectroscopy.

The various binding modes of lead in its divalent and tetravalent oxidation states are described. An analysis of high-resolution, high-precision crystal structures and ab initio molecular orbital optimizations of several gas-phase lead complexes were conducted. Objectives of the study include the identification of the conditions influencing the stereochemical activity of the lone pair of of Pb(II) electrons and to analyze conditions related to coordination numbers and preferred ligands. Results indicate that the lone pair orbital has little or no p character when the geometry is holodirected.

Research was conducted to examine the mechanistic aspects of the electrocatalytic oxidative cleavage of 1,2-diols by electrogenerated Pb(IV). Voltammetric data derived by both channel flow cell and rotating disk electrode experiments are examined using numerical simulation. Results reveal the importance of the structural features of the diols in modifying the ligand sphere of the intermediate Pb(IV) metal complex, thereby shifting the sensitive preequilibria for this highly fluxional system.

Rf magnetron sputtering of lead-rich targets was performed to prepare perovskite lead scandium tantalate (PST) thin films. The results indicate that the lattice dimensions of the films were significantly larger than that for bulk PST of the same composition. Moreover, large amounts of excess lead were found in the perovskite grains. The excess lead occupies the B sites in the perovskite structure as Pb4+.

A study was conducted on the influence of lead vacancies on the R-nFe transition in a Pb(B'1/3B'2/3)O3 compound. The results indicate that both the relaxor behavior and the phase transition are strongly dependent on the lead vacancies content. Moreover, a change in the polar clusters size resulting from lead vacancies formation weakens the dipolar interactions and inhibits the spontaneous relaxor to ferroelectric phase transition.

Studies reveal that early large-scale atmospheric pollution of lead from 600 BC to 300 AD as evidenced by the high concentration of lead from Carthaginian and Roman Spanish mines in ancient Greenland ice. A depression in 206Pb/207 Pb ratio between the two time periods with lead concentration of as low as 0.9 pg/g was measured.

Goethite-adsorbed lead (Pb) plays a key role in the in situ bioremediation of soil Pb. The interaction between goethite-adsorbed Pb and labile soil Pb species results to the reduction of the bioavailability of adsorbed Pb into insignificant levels. The study utilized a synthetic geothite and synthetic hydroxyapatite to represent adsorbed Pb and soluble phosphate, respectively. Results indicated that the adsorption and desorption of Pb is influenced by hydrogen-ion concentration or pH and that the sorbed Pb is equilibrated with free Pb2+ ion in the solution.

The gas phase concentration of lead oxide decreases and the homogenous nucleation of lead species is inhibited when the silicon precursor is oxidized to produce silica particles in the high temperatures, followed by the spectroscopy of PbO(g). The injection of gas phase silica sorbent precursors yielded larger lead particles that are immobilized and confined within a silica matrix.

Sublethal exposure to lead elicits changes in behavior, particularly learning. Previously, we had shown that bullfrog tadpoles exposed to 1 mg Pb/liter for 7 days exhibit learning deficits in a discriminate avoidance learning assay. The precise mechanisms involved in these lead-induced learning deficits are not understood, but CNS monoamine neurotransmitter systems have been implicated in the learning process. In the present study, we exposed bullfrog tadpoles to 1.7 [+ or -] 0.2 mg Pb/liter for 7 days and then compared concentrations of neurotransmitters from whole brain samples with those of controls. Serotonin or 5-hydroxytryptamine (5-HT) was significantly decreased in the lead exposed group while the serotonin metabolite, 5-hydroxyindoleacetic acid, (5-HIAA) was similar to controls. No changes were observed in the catecholamines epinephrine and norepinephrine following lead exposure. The ratio of 5-HIAA/5-HT was significantly increased in lead exposed animals as a result of the decrease in 5-HT, suggesting a decrease in 5-HT biosynthesis rather than an increase in 5-HT metabolism. These findings are the first to suggest that lead exposure in bullfrog tadpoles affects the monoamine neurotransmitters that are implicated in the learning process. The results of the present study, in conjunction with previous evidence of learning deficits following lead exposure, offer the possibility of correlating lead exposure with learning deficits and alterations in CNS neurotransmitters in bullfrog tadpoles. The use of this tadpole model shows promise as a means to examine and understand the mechanisms involved in lead neurotoxicity.

The lead (Pb) isotopic compositions of airborne particulate matter reported in France and the UK underscore their importance in the European Union's (EU) efforts to protect the environment. The ratios of (super206)Pb and (super207)Pb in gasoline were found to range from 1.061 to 1.094 with France and the UK having an average value of 1.084 and 1.067, respectively. The significance of gasoline-derived Pb as a tool in anthropogenic processes has decreased following the recent EU rule that limits concentrations of Pb in gasoline.

The blast-furnace waste generated in steel plants has been converted into a low-cost adsorbent. The resulting activated slag has been characterized and used for the removal of lead and chromium. The effect of pH, sorbent dosage, adsorbate concentrations, presence of other metal ions, temperature, and contact time on the sorption of lead and chromium were studied in batch experiments. Kinetic studies were undertaken to have an idea of the mechanistic aspects of the process. The uptake of lead is found to be greater than that of chromium. Adsorption on activated slag follows both Freundlich and Langmuir models. In addition, a series of fixed-bed experiments were performed in an attempt to simulate industrial conditions. The bed-depth-service-time (BDST) model proposed by Hutchins was successfully applied to the sorptive removal of lead. Some experiments were also performed with a view to recover [Pb.sup.2+] and chemically regenerate the spent slag columns in situ.

The search for novel leads is a critical step in the drug discovery process. Computational approaches to identify new lead molecules have focused on discovering complete ligands by evaluating the binding affinity of a large number of candidates, a task of considerable complexity. A new computational method is introduced in this work based on the premise that the primary molecular recognition event in the protein binding site may be accomplished by small core fragments that serve as molecular anchors, providing a structurally stable platform that can be subsequently tailored into complete ligands. To fulfill its role, we show that an effective molecular anchor must meet both the thermodynamic requirement of relative energetic stability of a single binding mode and its consistent kinetic accessibility, which may be measured by the structural consensus of multiple docking simulations. From a large number of candidates, this technique is able to identify known core fragments responsible for primary recognition by the FK506 binding protein (FKBP-12), along with a diverse repertoire of novel molecular cores. By contrast, absolute energetic criteria for selecting molecular anchors are found to be promiscuous. A relationship between a minimum frustration principle of binding energy landscapes and receptor-specific molecular anchors in their role as 'recognition nuclei' is established, thereby unraveling a mechanism of lead discovery and providing a practical route to receptor-biased computational combinatorial chemistry.

The anthropogenic nuclide 137Cs is widely used to measure soil movement. However, changes in 137Cs areal concentrations may not result from soil redistribution alone. There can be considerable variability in 137Cs fallout due to rain shadowing and small-scale runon-runoff processes at the time of deposition. Fallout 210Pb is also affected by these processes and thus areal concentrations of the two should be correlated. The ratio of fallout 210Pb to 137Cs reduces variability by up to a factor of two in undisturbed control forest sites at St. Helens, Tasmania. In addition, these two nuclides penetrate to different depths, thereby producing a varying activity ratio with depth, and this gives rise to a new method for determining soil loss. The average inventory ratios of fallout 210Pb to 137Cs from plots adjacent to the controls were measured; these had undergone 'normal' and 'minimal impact' logging procedures. The average core inventory ratio at the control locations was 2.24 [+ or -] 0.14 (n = 18), compared with means of 0.74 [+ or -] 0.09 (n = 10) and 1.73 [+ or -] 0.29 (n = 10) from the normal and minimal impact sites. The average depth of soil removed from the logged sites was then calculated by comparing these ratios with the inventory activity ratio curve from their respective control sites (40 [+ or -] 6 mm, normal site; 17 [+ or -] 5 mm, minimal site). We concluded that, compared with areal concentrations alone, ratios of fallout nuclides are likely to provide a less randomly variable (and thus more sensitive) method for investigating surface erosion in landscapes where vertical soil mixing is not sufficiently recent to be of concern.

Humic substances enhance binding of metal complexes to organic matter in natural waters. Potentiometric and voltammetric experiments show that there is competition in complexation of organic matter in the presence of the metals aluminum (Al3+) and lead (Pb2+). The competition between Al3+ and Pb2+ for the complexing groups of humic matter is influenced by the electrostatic nature of aluminum, which affects the charges of the complexing sites of the molecule. Complexation is also influenced by aluminum and humic matter concentrations.

Lead solid-phase speciation and release kinetics of separates less than 250 micrometers were investigated to determine potential bioaccessibility of lead from mining and smelting impacted solids. A set of 66 soil and 19 waste samples gathered from a town in Colorado were analyzed. Data indicated the presence of at least two lead pools reacting at different rates during two simultaneous first-order reactions. Mine waste impacted solids were found to readily emit lead under simulated gastric conditions.

A model based on the use of genetic algorithms to combinatorial/multiple synthesis was constructed to guide the chemical synthesis for structure optimization of active leads. It involves synthesis of the compounds in smaller sets, which are assayed, and the results of biological evaluation are used as information source to determine the specificity, selectivity and other important properties of the compounds. Synthesis and biological evaluation of several generations of the substrates led to the identification of Ser(OBn) as the optimal and most selective residue for stromelysin.

The salts of the plumbite anions, nido-Pb(sub 9)(super 4-) and closo-Pb(sub 9)(super 3-) are isolated and characterized structurally. Isolation of the anions is done by extracting KPb(sub 2.05) in ethylenediamine. The anions have monocapped square antiprismatic and Teller distorted tricapped trigonal prismatic geometries. The study shows that for Pb(sub 9)(super 4-) and Pb(sub 9)(super 3-), the C(sub 4v) and C(sub 2v) symmetries are in correlation with experimentally determined structures.