Source Of Lead Research Articles

Investigation on spectral profiles of white light generated by a smart tuneable LED source at different CCTs for optimized circadian performance

Light plays a critical role in regulating the human circadian system, influencing various physiological and psychological processes. Recently, smart tuneable LED sources have been extensively used, yet insufficient attention is given to their circadian performance, a crucial factor impacting human health and well-being. This study examines the luminous and circadian efficacies of STL white light with varying correlated colour temperatures (CCTs) and compares them to CIE standard light sources. Results show that STL white light exhibit different circadian efficacies than the corresponding spectra of standard light source. In the present article, a theoretical approach is proposed to optimize STL spectra by deconvoluting it into constituent bands and adjusting optical power to mimic the circadian action factor (CAF) values of standard light. The method could be advantageous in achieving tunability in CAF of STL sources and matching circadian performance of standard light sources.

Optimization of deposition time and temperature for high-quality PbS thin films via chemical bath deposition

In this study, lead sulfide (PbS) thin films were synthesized using chemical bath deposition (CBD) on glass substrates, employing lead nitrate and thiourea as source of Lead and Sulfur respectively, and triethanolamine was used as complexing agent. The research systematically examined the impact of two key parameters: deposition time (30-90 minutes) and bath temperature (55-90°C), revealing intricate relationships between deposition conditions and film characteristics. Deposition time analysis demonstrated a non-linear transmittance trend, with values changing from 20% at 30 minutes to 8% at 60 minutes, before recovering to 10% at 90 minutes. Additionally, the band gap changed from 2.00 eV at 30 minutes to 1.63 eV at 60 minutes and then increased to 1.70 eV at 90 minutes. Temperature variations showed a progressive decrease in transmittance from 23.75% at 55°C to 11% at 90°C, accompanied by a corresponding band gap reduction from 1.80 eV to 1.50 eV. The optimal conditions for producing high-quality PbS thin films suitable for p-type solar cell applications were determined to be a deposition time of 45 minutes and a bath temperature of 90°C, which effectively balance transmittance and band gap requirements. These findings provide crucial insights for enhancing PbS thin film performance in solar cell and infrared detection technologies, demonstrating the significance of precise parameter control in chemical bath deposition.

Metal resources and Han immigrants: Lead isotope analysis of metal relics excavated from Heimajing cemetery in Gejiu, Yunnan, China

AbstractThe Heimajing cemetery of the Han Dynasty is in southwestern China's most famous tin‐mining area. Smelting relics, such as tin ore and lead ingots, unearthed from Heimajing cemetery indicated the people were probably involved in mining and smelting. We used chemical composition and lead isotope analyses to study 76 samples from bronze artifacts and metallurgical remains. The results show that Han‐style bronzes, such as bronze hu, pan, ear cups, and other household utensils, as well as coins, are mainly lead–tin bronzes, while Southwest barbarian‐style objects such as spears, ge, and chu are copper or tin–bronze. Lead isotope analysis shows that these bronzes and metallurgical remains were mainly produced locally using the mineral sources of the Gejiu region. Not only are Heimajing bronzes stylistically similar to Han‐style bronzes of the Lingnan region, but also the source of the bronze material in both places is the same, both from the local mine in Gejiu. We speculate that the mining and metallurgical activities of metal mineral resources in Gejiu attracted many people from Lingnan. Then, they transported raw metal materials to the outside world, so Gejiu quickly became a center for supplying lead and tin raw materials during the Han Dynasty. Lead and tin sources from Gejiu have been transported to the Yungui Plateau, Lingnan, and Southeast Asia.

Nitrate accumulation and mineral nutrition of lettuce under varied light emitting diode lighting

This study aims to investigate strategies to minimize nitrate accumulation in lettuce to mitigate its potential harmful effects on human health. Lettuce cultivation under light-emitting diode lighting (LED) is becoming increasingly popular, and determining the effects of different LED sources on lettuce nutrition and nitrate accumulation is an important topic. The effects of different nitrate levels in the nutrient solution and different LED sources on lettuce nutrition and nitrate accumulation have been investigated under controlled conditions. Lettuce plants were grown for 48 days under White (W), Blue (B), Blue + Far Red (B + FR), Red (R), Red + Blue (R + B), Red + Far Red (R + FR), Red + Blue + Far Red (R + B + FR) LED lights using nutrient solutions containing 20, 24, and 28 mM nitrate. The highest marketable yield was obtained under B lighting, followed by R, R + B, R + FR, and R + B + FR. To reduce nitrate accumulation, lighting setups using W, R + B + FR, R + B, and R have proven to be advantageous. In these treatments, nitrate levels were determined to be 1039, 1118, 1167, and 1170 mg kg−1, which were lower compared to the other treatments. The concentrations of measured nutrients in plants were highest under B + FR, R + FR, and R + B lighting. The total chlorophyll concentration increased with the N dose, with the highest levels observed in the B, B + RF, and R + B + FR treatments. In conclusion, LED lighting influences lettuce nutrition and nitrate accumulation, with W, R + B + FR, R + B, and R treatments most effective in reducing nitrate levels. These findings should be validated in commercial greenhouse conditions to assess their practical applicability for large-scale production.

Advancing Public Health Interventions: A Novel Surveillance System for Hazardous Consumer Products.

Lead poisoning remains a significant public health concern with preventable exposure from different sources, including certain traditional consumer products. To address the concern of product-related lead exposures, the New York City Department of Health and Mental Hygiene has developed the Non-Paint Sample Database (NPSD). NPSD systematically tracks information about hazardous consumer products collected during New York City case investigations and store surveys. NPSD has enabled identification of new products-related lead sources and populations at risk of lead exposure and has guided risk communication, regulatory activities, and policy initiatives. Since 2007, approximately 8000 consumer products have been tracked by NPSD. NPSD demonstrates the potential for consumer product surveillance to enable source identification, monitor lead exposure trends, and facilitate effective educational and enforcement activities, which advances lead exposure prevention strategies.

Fast and Facile Synthesis of Cobalt-Doped ZIF-8 and Fe3O4/MCC/Cobalt-Doped ZIF-8 for the Photodegradation of Organic Dyes under Visible Light.

Co-doped ZIF-8 as a water-stable visible light photocatalyst was prepared by using a one-pot, fast, cost-effective, and environmentally friendly method. The band structure of ZIF-8 was tuned through the incorporation of different percentages of cobalt to attain an optimal band gap (E g) that enables the activation of ZIF-8 under visible light and minimizes the recombination of photogenerated charge carriers. A magnetic composite of Co-doped ZIF-8 was also synthesized to facilitate catalyst recycling and reusability through the application of an external magnetic field. Surface modification of magnetic Fe3O4 nanoparticles with microcrystalline cellulose (MCC) was used to reduce the level of agglomeration. The photocatalytic activities of Co-doped ZIF-8 (Co-ZIF-8) and Fe3O4/MCC/Co-ZIF-8 were evaluated for the photodegradation of methylene blue (MB) under visible light irradiation from a 20 W LED source. Co-ZIF-8 showed considerably higher photocatalytic activity than pure ZIF-8, confirming the success of the doping strategy. Both Co20%-ZIF-8 and Fe3O4/MCC/Co20%-ZIF-8 exhibited similar and remarkable photocatalytic activity under visible light (achieving 97% MB removal). The mechanism of photodegradation of MB by Fe3O4/MCC/Co20%-ZIF-8 was studied, revealing a first-order degradation kinetics (k = 13.78 × 10-3 min-1), with peroxide and hole species as the predominant active reagents. The magnetic composite successfully displayed recyclability and reusability over multiple cycles with negligible reduction in MB photodegradation efficiency.

Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA

Great Salt Lake is a critical habitat for migratory birds that is threatened by elevated metal concentrations, including mercury (Hg) and lead (Pb), and is subject to severe hydrologic changes, such as declining lake level. When assessing metal profiles recorded in Great Salt Lake sediment, a large data gap exists regarding the sources of metals within the system, which is complicated by various source inputs to the lake and complex biogeochemistry. Here, we leverage Hg and Pb stable isotopes to track relative changes in metal source contributions to Great Salt Lake over time. Mercury and Pb concentrations increase in sediments deposited after 1920 and peak between 1965 and 1995, following closure of several local smelters and the onset of increased emission controls. The nominal associations above are confirmed via Hg stable isotopes in pre-1920 background sediments, which reflect atmospheric inputs from regional and global origin, whereas Hg and Pb stable isotopes together indicate that elevated metal concentrations in mid-late 20th century sediments reflect increased mining/smelting inputs. The observed minimal rebound towards pre-1920 Pb isotope signatures in 21st century sediments indicates that mining/smelting inputs, though reduced, remain a primary source of Pb to Great Salt Lake. In contrast, the more pronounced rebound of Hg stable isotope signatures to pre-1920 values indicate a greater contribution of atmospheric inputs of regional/global origin to current Hg inputs, though Hg concentrations are ~10 times greater than pre-1920 background values due to global increases in atmospheric Hg concentrations or possibly slow recovery from local contamination. The importance of regional/global Hg sources to the system suggests that reductions in Hg bioaccumulation in the open water food webs of Great Salt Lake are more dependent on national and global reductions in Hg emissions and management strategies to limit methylmercury production within system. This work highlights the utility of using coupled Hg and Pb stable isotope values to assess trace metal pollution sources and pathways in aquatic systems.

Utilizing lead isotopes in airborne particulates and soils to trace lead sources: A case study from southern Taiwan

Utilizing lead isotopes in airborne particulates and soils to trace lead sources: A case study from southern Taiwan

Application of Fine-Grain Carbon Materials in the Process of Smelting Lead from Battery Paste.

The recycling of used lead-acid batteries is currently the main source of lead in the world. More than 50% of the weight of a used lead-acid battery is battery paste, in which lead occurs in compounds with oxygen and sulfur. In pyrometallurgical processes of battery paste, coke or coke breeze is used as a traditional additive acting as a fuel/reducer. Due to the constantly high prices of these materials, research is being carried out to find alternative (equally efficient but cheaper) carbon-bearing materials. Those materials can be technological replacements for coke or coke breeze in pyrometallurgical processes. The aim of the presented work was to check the possibility of using fine-grained carbon-bearing materials, in the form of anthracite dust and coal flotation concentrate, for battery paste processing, as replacements for traditionally used coke and coke breeze. As part of the presented work, the following tests were carried out: thermogravimetric tests using battery paste, processes of smelting battery paste in a pit furnace, and processes of smelting battery paste in a rotary furnace. The research results indicate that fine-grained carbon-bearing materials, in the form of anthracite dust and coal flotation concentrate, can be successfully used as a replacement for traditionally used fuels/reducers.

Optoelectronic oscillator using visible LEDs and plastic optical fibers.

This paper describes an optoelectronic oscillator (OEO) capable of accepting CW light as input and providing radio-frequency (RF) carriers as output. To the best of our knowledge, we are the first to describe an easy-to-assemble and low-cost OEO that uses visible LED sources with a standard 1mm diameter plastic optical fiber as part of the oscillation ring. The gain is solely provided by a transimpedance pre-amplifier integrated with a photodetector. Self-oscillations occurred. Fundamental frequencies in the 7.7-26.5MHz range were generated, since the length of the fiber and the bias current feeding the LED are both correctly tuned. A comprehensive approach is used to explain the operation of the OEO. The proposed OEO may be didactically useful for use in research or teaching laboratories by untrained people.

Unraveling lead sources in a tropical urban Swamp Forest: Insights and challenges

We investigate the contributions of natural (geogenic) and anthropogenic sources of lead (Pb) to the Nee Soon Swamp Forest, a relatively undisturbed catchment in Singapore. Using a Bayesian statistical source tracking approach with Pb isotopes preserved in sediment sections, our findings reveal a predominance of geogenic Pb in contemporary sediments, despite the significant presence of anthropogenic Pb in aerosols from local and distant sources. However, the geogenic Pb isotope signatures of the two main soil types in the catchment overlap with those of anthropogenic sources, introducing considerable uncertainty in using Pb isotopes as tracers within this catchment and potentially across larger areas. This uncertainty raises concerns about past interpretations of Pb contamination in both terrestrial and aquatic environments in Singapore and the broader region. To address these challenges, we emphasize the importance of accurately determining the signatures of all natural sources before using Pb isotopes as tracers in future studies. We also suggest that incorporating additional Pb isotope ratios or other stable isotope ratios (e.g., Ba, Cu, Sr, Zn) could enhance our ability to distinguish between natural and anthropogenic Pb sources. Ultimately, our study highlights the complexity of Pb sources in the environment and underscores the need for more comprehensive approaches to assessing their impacts. SynopsisThis paper highlights insights and challenges in lead (Pb) source tracing studies conducted in urban catchments. These challenges primarily stem from the inadequate identification of all Pb isotope sources. We address these challenges by employing a Bayesian statistical approach to effectively identify, discriminate, and quantify Pb sources within a wetland ecosystem in Singapore.

Spectral Dependence of Inhibitory Effect of Blue Light on Cancer Cells and Efficacy of Light-Induced Intracellular Generation of Reactive Oxygen Species In vitro

A quarter of a century after establishment of inhibitory effect of blue light on growth of cancer cells, many aspects of mechanism of photophysical and photochemical processes underlying the effect of above physical factor have been quite well studied. However, the most controversial question remains about molecules-acceptors of optical radiation. Important information about possible participation of particular endogenous compound in the implementation of photobiomodulation effect can be obtained from comparison of its absorption spectrum and spectrum of action of optical radiation on cells. In this regard, we studied the spectral dependence of light-induced changes in metabolic activity of HeLa cells as well as the dependence of ROS level formation in cells when exposed to radiation from LED sources, peaking at λmax = 395, 405, 415, 445,465 nm, in the energy dose range of 1.5-15.0 J/cm2. It has been shown for the first time that inhibitory effect of blue light as well as the level of light-induced ROS formation decrease with increasing wavelength of applied radiation. A new pattern has been established, consisting of change in the contribution of various types of ROS to photobiological effects recorded at different time intervals after the cessation of cell irradiation.

NOR Gate Based LED Inverter

In this paper, the design and simulation of the LED inverter circuit using NOR gate in Proteus software is described. The aim of the practical is to show that simple digital inverter can be created with the NOR gate which is the universal gate and the LED will be used to show that the logic circuit is working. Incidentally, to turn the NOR gate into an inverter, it simply involves linking both inputs together and that simplifies all the layout. The simulation of the circuit was done using proteus software and as the input of the NOR gate-based inverter is changed the output LED source is also changed, and the functionality of the circuit is proved. The paper includes information about control Nor Gate in inverter configuration, the significance of digital logic circuit in basic electronics, and the utility of the Proteus software within learning and prototyping settings. The outcome supports that a NOR gate can invert depicted input indication and can power an LED in a straightforward, low-priced circuit, which forms the basis of more complicated digital set of rules circuits

Exploring circulation dynamics in Han Dynasty China: insights from isotopic analysis of lead glazed pottery

This study investigates lead provenance and circulation patterns in Han Dynasty (202BC-220AD) China through the analysis of lead glazed pottery. Four objects were studied using a combination of typological study, elemental chemistry and lead isotope ratio analysis. The results for each object were compared with databases of ‘lead mining districts’ (lead deposits) and ‘lead usage districts’ (lead-containing artifacts unearthed in different spatial and temporal ranges) to assess the lead sources used for each sample and offers a spatial-temporal range of the use of these lead resources. Three distinct groups of lead and their possible circulating spatial-temporal scales are identified across six samples in this study. A possible change in lead supply networks between the Western Han Dynasty (202BC-9AD) and the Eastern Han Dynasty (25AD-220AD) is proposed. This study also highlights the probable changes in the movement of lead resources from the Western Han Dynasty to the Tang Dynasty (618AD-690AD), suggesting improvements in long-distance transport capabilities, and the development of economic divisions and exchange connections in ancient Chinese society. Our findings contribute to a deeper understanding of the economic and political dynamics during the Han Dynasty and emphasize the significance of lead isotope analysis of glazed pottery in exploring resource movement.

Lead‐based ammunition is a threat to the endangered New Zealand Kea (Nestor notabilis)

AbstractLead (Pb) poisoning is a significant threat to Aotearoa New Zealand's endangered kea (Nestor notabilis), an avian species important to Māori. Historically, exposure was thought to be from lead‐containing building materials; however, recent field observations suggest lead‐based ammunition as an additional source. We used stable lead isotopes to investigate the sources of lead to kea. Comparing 207 Pb/206 Pb ratios in kea blood (n = 91) to both ammunition and building materials, we found approximately one‐third of exposed kea (blood lead > 10 µg/dL) had lead isotope ratios consistent with exposure to lead‐based ammunition. As lead ammunition is still used, including in government‐sponsored culling programs, our data indicate an urgent need to shift toward non‐lead ammunition use to prevent further poisoning and aid conservation efforts. Collaborating with tangata whenua/Māori guardians, we advocate for immediate policy changes to eliminate lead‐based ammunition in kea habitat to safeguard this endangered culturally treasured species from extinction.

Risk assessment and source tracing of heavy metals in major rice-producing provinces of Yangtze River Basin

Heavy metal contamination in rice constitutes a global concern, its migration is influenced by environmental factors as well as socioeconomic activities. However, tracing its origins within complex context remains a significant challenge. The concentrations of five heavy metals (HMs) in 1754 samples from major rice-producing provinces were analyzed, and their pollution characteristics, associated health risks and temporal-spatial variations were discussed. Potential sources were classified by positive matrix factorization (PMF) models, considering correlations with human activities, climatic conditions, and interaction within ecosystems. The results showed that cadmium (Cd) and arsenic (As) were the primary contributors to pollution risk, with the borders between Hunan and central Jiangxi, as well as northeast Jiangxi and northwest Anhui, identified as critical areas for risk management. PMF serves as an effective methodology for identifying the sources of HMs in rice. Industrial activities, particularly mining and transportation, represent the predominant sources of Cd and lead (Pb), accounting for 75.6 % of the total pollution. Conversely, agricultural practices and natural factors constitute the primary sources of As, contributing to the remaining 24.4 %. It is noteworthy that the rapid industrial development has facilitated the expansion of the freight industry, consequently increasing the risk associated with Pb. Furthermore, effective governmental policy management can mitigate the risks related to HMs. Our research highlights the influence of industrial development on HMs risk in various regions and the moderating role of policy formulation. SynopsisMinimal research exists on the impact of regional economic development on heavy metals in rice. This study reports mining and transportation activities increase carcinogenic risks caused by Cd and Pb in rice during industrialization.

Multi-omics inhalation toxicity assessment of urban soil dusts contaminated by multiple legacy sources of lead (Pb)

Although animal studies have evaluated lead (Pb) toxicity, they are limited to soluble forms, such as Pb-acetate, which do not reflect the range found in the exposome. Recent studies on Pb speciation of residential soils in urban areas revealed that the initial Pb sources are not persistent and are extensively repartitioned into adsorbed forms of Pb rather than insoluble phosphates. We investigated the inhalation and neurological toxicity of dusts generated from a surficial soil sample collected from a residential site with an exposomic mixture of various Pb species, both adsorbed phases (Fe and Mn oxide, humate bound Pb) and mineral phases (Pb hydroxycarbonate, pyromorphite, galena). Mice inhaled East Chicago dust (ECD) generated from a composite soil sample for 4 h/day, 7 days/week, for 4 weeks. Mice were necropsied immediately, 1, 14 and 30 days post exposure to evaluate both toxicity and recovery. Exposure to ECD caused changes in memory and spatial learning in the Morris Water Maze test. RNAseq analysis of the hippocampus region revealed multiple differentially expressed genes and impacts on pathways involved in ion channel complexes, and neuron-to-neuron synapse. Metabolomics analysis of plasma highlighted significant alterations in metabolic processes immediately after exposure that resolved after 14 days of rest.

Soft hydrogels obtained by photothermal curing of poly(vinylpyrrolidone)/gold nanoparticles dispersions showing anisotropic swelling and photo-activated antimicrobial properties

Poly(vinylpyrrolidone) (PVP) hydrogels were obtained by green light irradiation of aqueous PVP/ammonium persulfate solutions modified with gold nanoparticles (AuNPs). The increase in temperature produced through the activation of the photothermal effect of AuNPs triggers the decomposition of ammonium persulfate producing radicals that, by attacking the polymer main chain and generating macro-radicals, induce the crosslinking of the polymer via recombination paths. Irradiation from the top of the solutions in an open configuration produced water evaporation and a concomitant increase in temperature during curing, giving rise to dry materials with high aspect ratio and moderate swelling anisotropy. Pads that reversibly adhere to different substrates, including human skin, were produced by simple contact of the final materials with water. Impregnation of gauze wound dressings with PVP-Au-ammonium persulfate dispersions, followed by direct “in situ” photothermal crosslinking, enabled the fabrication of supported functional pads with potential applications as reversible adhesive skin wound dressings. Infusion of the hydrogels with Rose Bengal (RB) provides the materials with photosensitizing properties useful for the photodynamic inactivation of Staphylococcus aureus. A decrease in cell viability of 99.9% was attained after 30 min of irradiation with a low-power green LED source, which demonstrates the efficient singlet oxygen production by RB in the hydrogels and paves the way towards the design of new stimulus-activated bactericidal supplies for biomedical uses.

The spectral mismatch correction factor estimation using broadband photometer measurements and catalog parameters for tested white LED sources

Using a modeled look-up chart developed in this work, we show that accurate photometric measurements of characteristics like illuminance or luminous intensity of test LED sources can be measured in one step. This is a simple broadband measurement that may substitute for complicated and costly spectral measurements currently in place. To develop the look-up chart, the typical minimum and maximum of the Spectral Mismatch Correction Factor (SMCF) for a given photometers was estimated in relation to catalog parameters of the LEDs such as correlated color temperature (CCT) and melanopic daylight efficacy ratio (mDER). This research was based on the unique and large dataset of real photometers spectral response srel(λ) collected and measured at accredited laboratories located at America, Asia and Europe and modeled LED's spectral power distribution (SPD) data. Independent look-up tables were developed for color-mixed LEDs (cm-LEDs) and white phosphor-converted LEDs (pc-LEDs), two common LED types.

Sources of lead in a Tibetan glacier since the Stone Age

The Tibetan Plateau glaciers, among the world’s most remote and pristine places, provide water to millions and play a vital environmental role. We measured the lead isotopic composition in a dusty ice core from the Guliya ice cap in northwest Tibet, from approximately 36 thousand years Before Present (Stone Age) to 2015, to determine the onset and sources of anthropogenic lead. Despite the dust-laden nature of the core, a clear change in the lead isotope signature to below Stone Age levels started in 1949 followed by a rapid decrease in 1960 and an even more rapid decrease in 1974 indicating the first emergence of anthropogenic lead. Accurate isotopic lead measurements allowed us to better, and more sensitively, quantify sources using a Bayesian mixing model. Chinese gasoline was the primary anthropogenic source surpassing natural contributions in the 2000s until 2007 when emissions from leaded gasoline decreased and those from coal and lead-zinc ores increased.