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A recent California proposition led to awareness that lead is a stabilizer in the Polyvinyl Chloride (PVC) jacketing that covers conductors in Christmas lights. The objective of this study is to examine the level of accessible lead in Christmas lights. Following U.S. Environmental Protection Agency (U.S. EPA) Lead Inspectors' procedures, researchers at Cornel University and in Nebraska conducted wipe samples and total lead content samples of newly purchased and older Christmas light sets. Samples were analyzed for lead content. Lead was present in varying amounts on all samples. The amount of lead from the Nebraska samples, normalized to length of strings, was independent of analyzing laboratory, analysis method, age of string, and repeat sampling, both immediately and after extended storage. A later analysis of these same strings by the Cornell team showed diminished quantities. Amounts of surface lead normalized to crude estimates of the area of light string indicated surface concentrations in excess of U.S. EPA clearance level for lead on window sills. Whether exposure to lead in Christmas lights affects blood lead levels in humans is unknown. No standards exist for lead content in this product, and no protocols exist for conducting tests on it. Therefore, consumers may wish to exercise caution to reduce possible exposure., Introduction Humans have had a long relationship with lead. Before 1550 BCE, Egyptians used lead-based compounds for external remedies, which, according to Nriagu (1983), suggests an appreciation for lead's toxic [...]

BACKGROUND: A previously conducted study of prenatal lead exposure and schizophrenia using [delta]-aminolevulinic acid, a biologic marker of Pb exposure, in archived maternal serum samples collected from subjects enrolled in [...]

BACKGROUND: Attention deficit/hyperactivity disorder (ADHD) and lead exposure are high-prevalence conditions among children. OBJECTIVE: Our goal was to investigate the association between ADHD and blood lead levels (BLLs) in Chinese [...]

BACKGROUND: Tactile defensiveness in children is associated with difficult social relations, emotional dysregulation, and inattention. However, there are no studies of lead exposure and tactile defensiveness in children or animals [...]

BACKGROUND: Given the association between iron deficiency and lead absorption, we hypothesized that variants in iron metabolism genes would predict higher blood lead levels in young children. OBJECTIVE: We examined [...]

BACKGROUND: Low-level developmental lead exposure is linked to cognitive and neurological disorders in children. However, the long-term effects of gestational lead exposure (GLE) have received little attention. OBJECTIVES: Our goals [...]

BACKGROUND: Few studies provide data directly relevant to the question of whether blood lead concentrations < 10 [micro]g/dL adversely affect children's cognitive function. OBJECTIVE: We examined the association between blood [...]

Heterolayered Pb([Zr.sub.1-x][Ti.sub.x])[O.sub.3] thin films with different combinations of constituted layers are examined. The wake-up phenomenon is reduced at elevated temperatures, thus leading to fatigue degradation at a relatively lower number of switching cycles.

A study was conducted to determine the effects of varying the [sigma]-electron donor ability of pyridine Lewis-base ligands on the coordination environment of lead(II) in bis-thiolate complexes. The results indicate that lead-nitrogen bond distances is reduced when [sigma]-electron donor ability of the 4-substituted pyridine ligand is increased.

BACKGROUND: It has been established that skeletal growth is stunted in lead-exposed children. Because chondrogenesis is a seminal step during skeletal development, elucidating the impact of Pb on this process is the first step toward understanding the mechanism of Pb toxicity in the skeleton. OBJECTIVES: The aim of this study was to test the hypothesis that Pb alters chondrogenic commitment of mesenchymal cells and to assess the effects of Pb on various signaling pathways. METHODS: We assessed the influence of Pb on chondrogenesis in murine limb bud mesenchymal cells (MSCs) using nodule formation assays and gene analyses. The effects of Pb on transforming growth factor-[beta] (TGF-[beta]) and bone morphogenetic protein (BMP) signaling was studied using luciferase-based reporters and Western analyses, and luciferase-based assays were used to study cyclic adenosine monophosphate response element binding protein (CREB), [beta]-catenin, AP-1, and nuclear factor-kappa B (NF-[kappa]B) signaling. We also used an ectopic bone formation assay to determine how Pb affects chondrogenesis in vivo. RESULTS: Pb-exposed MSCs showed enhanced basal and TGF-[beta]/BMP induction of chondrogenesis, evidenced by enhanced nodule formation and up-regulation of Sox-9, type 2 collagen, and aggrecan, all key markers of chondrogenesis. We observed enhanced chondrogenesis during ectopic bone formation in mice preexposed to Pb via drinking water. In MSCs, Pb enhanced TGF-[beta] but inhibited BMP-2 signaling, as measured by luciferase reporter assays and Western analyses of Smad phosphorylation. Although Pb had no effect on basal CREB or Wnt/[beta]-catenin pathway activity, it induced NF[kappa]B signaling and inhibited AP-1 signaling. CONCLUSIONS: The in vitro and in vivo induction of chondrogenesis by Pb likely involves modulation and integration of multiple signaling pathways including TGF-[beta], BMP, AP-1, and NF[kappa]B. KEY WORDS: BMP signaling, chondrogenesis, lead, mesenchymal stem cells, TGF-[beta] signaling. Environ Health Perspect 115:1276-1282 (2007). doi:10.1289/ehp.10028 available via http://dx.doi.org/ [Online 3 July 2007], In spite of effort to reduce human exposure, lead toxicity continues to be a major environmental health concern in the United States and in other industrial countries. Although recent research [...]

The crystal growth and infrared spectroscopic properties of Nd doped lead chloride (Nd:Pb[Cl.sub.2]) which were obtained by a self-seeded Bridgman technique is described. The findings from the spectroscopic properties reveal that (Nd:Pb[Cl.sub.2]) could be used as a promising low-phonon energy material for solid-state laser application at near-IR and mid-IR wavelengths.

La Isabela, the first European town in the New World, was established in 1494 by the second expedition of Christopher Columbus but was abandoned by 1498. The main motive for settlement was to find and exploit deposits of precious metals. Archaeological evidence of silver extraction at La Isabela seemed to indicate that the expedition had located and tested deposits of silver-bearing lead ore in the Caribbean. Lead isotope analysis refutes this hypothesis but provides new evidence of the desperation of the inhabitants of La Isabela just before its abandonment. archaeological science | historical metallurgy | La Isabela | lead isotopes

A study of PbS nanoparticles having a fairly narrow size distribution (10 -12 %) prepared in situ within a sulfonated polystyrene random ionomer is reported. Photoluminescence (PL) analysis showed that the nanocomposites emit in both the visible and near-infrared regions, with the infrared PL size-tunable in the range 1100-1500 nm.

Because of the broad interest in high energy and nuclear physics community, mass production capacities of lead tungstate crystals have been established. The optical and scintillation properties of lead tungstate crystals, 20 each from two major vendors, were evaluated. The transmittance, emission and excitation spectra, light output and light response uniformity of these samples were measured. The degradations of these properties under irradiation, and the emission weighted radiation induced absorption coefficient (EW RI AC) were also studied. It was found that currently mass-produced lead tungstate crystals are radiation hard enough for radiation environments where expected dose rates do not exceed a few hundred rad/h. Index Terms--Crystal, emission, lead tungstate, light output, radiation damage, scintillator, transmission.

It has been proved that doubly charged lead monohydrate can be synthesized may be in low yields, from ligand exchange resulting in energized collisions, between three hydrated ions. These ions are stable against any dissociative charge transfer.

Ten pieces of Y-Ba-Cu-O bulk current leads are fabricated and transport properties in liquid nitrogen at an applied magnetic field of 0.5 T is investigated. A transport model of this type of current leads for predicting the I - V characteristics and the critical current, and confirmed that the predicted behavior agrees well with the experimental results.

Studies of prokaryotic tolerance and resistance to soluble lead have revealed an efflux mechanism as well as precipitation of lead in an insoluble form and three pleitropic vibrio harveyi mutants were observed for precipitate soluble Pb2+ as an insoluble compound. One of the V-harveyi mutants showed little or no response to intercellular signals from other V-harveyi inocular and it is suggested that V-harveyi carries at least one quorum sensor that is dedicated to receiving cross-species communication.

The effect of the imprint on the operation of ferroelectric random access memory (FeRAM) is estimated. A quansitheoretical model is used that includes the hysteresis shift along the voltage axis and the depolarization induced by the hysteresis shift.

Research describing the the mechanical damping effect of lead metaniobate is presented. For the research, an instrument for determining viscoelastic measurements in bending and torsion was used.

A new study describes the radiolytic reduction of lead ions in aqueous solution and investigates the interaction of lead nanoparticles with various oxidizing solutes.

Calculations of the (super)207 Pb and (super)183 W NMR chemical shifts have been performed by means of Pauli spin-orbit Hamiltonian and the relativistic zero order regular approximation (ZORA). Results indicate that ZORA's chemical shift is in better agreement with the experiment than that of Pauli spin-orbit scheme.

The annealing of PbWO4 crystals, conducted at temperatures over 740 degrees Celsius in air, is shown to be an effective technique of washing out the intrinsic color centers. This leads to the development of a 350 nm optical absorption band and the improved radiation hardness of the PbWO4 crystals. The conversions of the intrinsic 350 nm color centers into temporary 410 nm color centers were also evident during the radiation procedure conducted during the experiment.

PbTiO3 films of 21, 64, 128, 210, 310 and 420 nm thicknesses were produced on (0001) sapphire through the sol-gel technique. Raman scattering and x-ray diffraction methods were employed to investigate the correlation between the film thickness and the structural changes on these films. The Raman and x-ray intensities in 21 nm films were too weak to show any structural data, while all other films showed tetragonal structure. At room temperature, the variation of lowest E(1TO) phonon mode frequency with film thickness was observed due to compressive stresses in the films.

Research was conducted to examine the microstructural and nonlinear optical properties of silica-titania sol-gel film doped with PbS quantum dots. X-ray diffraction, high-resolution transmission electron microscopy and Rutherford backscattering spectrometry were used for the analysis of structural characteristics while the nonlinear m-line method and degenerate four-wave mixing were used for the study of the resonant nonlinear optical characteristics. It was found that sol-gel is a well-adapted method for the production of semiconductor doped thin glass films.

Thin films of Pb(Zr(sub x)Ti(sub 1-x))O(sub 3) (Me = Al, Nb) (PZT) were produced by spincoating of material synthesized by a sol-gel technique. The S(100)/SiO2/Ti/Pt layer sequence was used as substrate, applying the usual arrangement for ferroelectric random access memories. Macrostresses and microstresses were determined. Findings showed that the macrostress behavior of the PZT thin films is not related to the doping species, while the microstress behavior is strongly related to doping species aluminum or niobium and the dopant concentration.

The investigation performed up to now on single crystals of PbW[O.sub.4] (PWO) provides the evidence of the possibility to optimise the optical properties of an intrinsic scintillator such as PWO: the control of essential requirements in the crystal preparation (raw material purity, growing methods and post-growth annealing) as well as the introduction of selected dopants at suitable concentrations (particularly trivalent and pentavalent ions) were found to be very successful in lowering the concentration of point defects in the lattice which strongly affect scintillation properties and radiation hardness. The optical transmission as well as light yield before and after irradiation was measured. The systematic investigation effort to better understand the scintillation characteristics and to improve the quality of PWO crystals is due to their use for the CMS electromagnetic calorimeter.

A study was conducted to analyze ab initio computations utilizing density functional theory within the local density approximation on PbO during the alpha-phase and idealized CsCl structure. An interactive matrix diagonalization technique was utilized to solve Kohn-Sham equations. Results indicated that the stabilization of the alpha-PbO structure over the CsCl structure correlated with the mixing of lead 6p states into the filled antibonding O 2p and Pb 6s states.

A study was conducted to analyze the domain structure of epitaxial PbTiO3 thin films on LaAlO3(100) prepared by metal organic chemical vapor deposition. The deposition of the thin films were performed in a low-pressure cold-wall horizontal quartz reactor. Experimental results indicated that growth of the epitaxial films on the single crystalline substrate led to an alternating a/c/a/c domain structure in the surface.

Radium analysis is carried out by batch adsorption from natural waters on basic lead rhodizonate supported on charcoal, LERHO, starting from 2-L samples. 133Ba is added to allow the measurement of the overall chemical yield by [Gamma] counting. Radium is recovered with a few milliliters of 1.5 M HCl, and lead is removed by a chromatographic column filled with Dowex 2 x 8. Finally 50 [[micro]gram] of barium carrier is added, and the radium is coprecipitated as sulfate on a preformed bed of barium sulfate, to prepare a sample suitable for [Alpha] and [Gamma] counting. The detection limit of the proposed method is 0.002 Bq/L 226Ra. This value is far beyond the radium activity admissible for drinking waters. Due to lack of appropriate samples, the procedure was tested using mineral waters spiked with 226Ra and two commercially available mineral waters with very low radium contents.