Metal Mixtures Research Articles

Effect of hydraulic retention time on sulfide production with sludge from hydrothermal vent sediments and its utilization on the removal of Cu, Zn, and Al

The present work aimed to evaluate the production of sulfide through the application of different hydraulic retention times (HRT) and different sulfate loading rates in an up-flow anaerobic sludge blanket (UASB) reactor utilizing acetate-butyrate as electron donors and the coupling of the reactor to a crystallizer to remove metals. The sulfidogenic sludge for the UASB was generated from hydrothermal vent sediments and this was operated at room temperature (18-22 ºC). The sulfate reduction process was linked to the precipitation of Cu2+, Zn2+ and Al3+ in a crystallizer coupled to the UASB reactor (two-stage system) to avoid the toxicity of the metals to the sludge. The concentration of dissolved sulfide increased with the HRT up to 312.9 mg HS–/L at 3 d of HRT. As the sulfate loading rate was increasing, the maximum sulfide concentration obtained was of 376.8 mg HS–/L at 500 mg SO4–2/L/d (1500 mg/L), whereas the concentration of Cu2+, Zn2+ and Al3+ was up to 150, 100, and 100 mg/L, respectively. The removal efficiencies of Cu2+, Zn2+, and Al3+ were higher than 98% when they were fed separately. When a mixture of metals was added, the removal efficiency was close to 80%. Recovery of metals was lower than 57% in all cases. The sulfide production was supported with acetate-butyrate, being the former commonly accumulated because of the oxidation of higher organic compounds; in this case, its utilization sustained sulfate reduction. This process could be controlled by parameters such as HRT and sulfate loading rate to improve the performance of the bioreactor in the treatment of the effluents contaminated with metals in a two-stage system.

Using Bayesian and weighted regression to evaluate the association of idiopathic oligoastenoteratozoospermia with seminal plasma metal mixtures

Idiopathic oligoastenoteratozoospermia (iOAT) affects 30% of infertile men of reproductive age. However, the associations between Cr, Fe, Cu, Se or Co levels and iOAT risk have not been determined. This research aimed to assess the associations between Cr, Fe, Cu, Se and Co levels as well as their mixtures in seminal plasma and the risk of iOAT and severe iOAT. Therefore, a case‒control study including 823 participants (416 iOAT patients and 407 controls) recruited from October 2021 to August 2022 at the reproductive medicine center of the First Affiliated Hospital of Anhui Medical University was conducted in Anhui, China. The concentrations of Cr, Fe, Cu, Se and Co in seminal plasma were detected via inductively coupled plasma‒mass spectrometry. Binary logistic regression models were used to assess the associations between the levels of Cr, Fe, Cu, Se and Co and the risk of iOAT and severe iOAT; additionally, Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regressions were performed to evaluate the joint effect of seminal plasma levels of Cr, Fe, Cu, Se and Co on the risk of iOAT and explore which elements contributed most to the relationship. We found significant associations between the concentrations of Fe, Cu and Se in seminal plasma and iOAT risk after adjusting for covariates (Fe, lowest tertile vs. second tertile: aOR = 1.86, 95% CI = 1.31, 2.64; Cu, lowest tertile vs. second tertile: aOR = 1.95, 95% CI = 1.37, 2.76; Se, lowest tertile vs. second tertile: aOR = 1.65, 95% CI = 1.17, 2.35). A lower Se concentration in seminal plasma (lowest tertile vs. second tertile: aOR = 1.84, 95% CI = 1.10, 3.10) was positively associated with the risk of severe iOAT. Additionally, we also observed an association between the concentration of Cr in seminal plasma and the risk of iOAT before adjusting for covariates (Cr, third tertile vs. lowest tertile: OR=1.44, 95% CI: 1.03, 2.02). According to the BKMR analyses, the risk of iOAT increased when the overall concentrations were less than the 25th percentile. The results from the WQS regression indicated that a negative WQS index was significantly associated with the iOAT risk, while a positive WQS index was not. Se and Fe had significant weights in the negative direction. In conclusion, lower Cu, Fe and Se levels in seminal plasma were positively associated with iOAT risk, while higher Cr levels in seminal plasma were positively associated with iOAT risk according to the single element model, and lower levels of Se were related to a greater risk of severe iOAT; when comprehensively considering all the results from BKMR and WQS regression, Fe, Se and Cr levels contributed most to this relationship.

Association between blood metals mixture and chronic kidney disease in adults: NHANES 2013-2016

BackgroundThe association between single metal exposure and chronic kidney disease (CKD) has been established. However, there is limited research on the effects of multi-metal mixtures and their potential age-specific associations with kidney injury. This study aimed to examine the relationship between metal mixtures and kidney function in adults, while also exploring the modifying effects of age. MethodsWe included a subset (n = 4250) of a nationally representative adult population in the National Health and Nutrition Examination Survey (NHANES) 2013–2016. Kidney function was assessed using the glomerular filtration rate (eGFR) and creatinine albumin ratio (ACR). The individual and combined effects of lead (Pb), cadmium (Cd), mercury, and manganese on kidney injury and the risk of CKD were evaluated. ResultsPb and Cd were found to be positively associated with decreased kidney function. For a one Ln-unit increase in lead and cadmium, the adjusted ORs of CKD were 1.60 (95% CI: 1.35, 1.90) and 1.41 (95% CI:1.12, 1.77), respectively. We also observed an interaction between lead and cadmium for ACR. We also observed the joint effect between Pb and Cd on eGFR, ACR and CKD. Stratified analysis found a higher risk of decreased kidney function among older individuals. The quantile-g calculation model further showed that metal mixture was associated with decreased kidney function and the risk of CKD (OR = 1.53, 95% CI: 1.22, 1.90). And lead and cadmium were the main contributors. And Pb and Cd were the major components that increased the risk of CKD. ConclusionCo-exposure to metal mixture were associated with reduced kidney function in adults, especially in older. Our findings support co-exposure to lead and cadmium as risk factors of CKD in adults.

The interpretable machine learning model associated with metal mixtures to identify hypertension via EMR mining method.

There are limited data available regarding the connection between hypertension and heavy metal exposure. The authors intend to establish an interpretable machine learning (ML) model with high efficiency and robustness that identifies hypertension based on heavy metal exposure. Our datasets were obtained from the US National Health and Nutrition Examination Survey (NHANES, 2013-2020.3). The authors developed 5 ML models for hypertension identification by heavy metal exposure, and tested them by 10 discrimination characteristics. Further, the authors chose the optimally performing model after parameter adjustment by Genetic Algorithm (GA) for identification. Finally, in order to visualize the model's ability to make decisions, the authors used SHapley Additive exPlanation (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME) algorithm to illustrate the features. The study included 19368 participants in total. A best-performing eXtreme Gradient Boosting (XGB) with GA for hypertension identification by 16 heavy metals was selected (AUC: 0.774; 95% CI: 0.772-0.776; accuracy: 87.7%). According to SHAP values, Barium (0.02), Cadmium (0.017), Lead (0.017), Antimony (0.008), Tin (0.007), Manganese (0.006), Thallium (0.004), Tungsten (0.004) in urine, and Lead (0.048), Mercury (0.035), Selenium (0.05), Manganese (0.007) in blood positively influenced the model, while Cadmium (-0.001) in urine negatively influenced the model. Study participants' hypertension associated with heavy metal exposure was identified by an efficient, robust, and interpretable GA-XGB model with SHAP and LIME. Barium, Cadmium, Lead, Antimony, Tin, Manganese, Thallium, Tungsten in urine, and Lead, Mercury, Selenium, Manganese in blood are positively correlated with hypertension, while Cadmium in blood is negatively correlated with hypertension.

Acute toxicity and bioaccumulation of common urban metals in Bombus impatiens life stages

Metal contamination is ubiquitous in urban areas and represents a risk to arthropod species. Bees are exposed to metals while foraging within contaminated landscapes from multiple sources. Eliminating the risk of bee exposure to metals is complex, and requires an understanding of how bees become contaminated, how metals accumulate within bee bodies, and how this exposure influences their health. We selected Bombus impatiens, the common eastern bumble bee, as our focal species because it is the most frequently encountered bumble bee species in the eastern United States and common within urban greenspaces. The aims of this study were to quantify the lethal concentration exposure limit (LC50) for B. impatiens foragers, assess the bioaccumulation ability of environmentally relevant concentrations of common urban metals in adults, larvae, and pupae, and compare the LC50 values against field relevant concentrations collected by foraging bumble bees within a legacy city. Bumble bees were orally exposed to arsenic oxide, cadmium chloride, or chromium oxide in sucrose solution to encourage consumption. The LC50 for arsenic (As2O3 36.4 mg/L), cadmium (CdCl2 10.3 mg/L), and chromium (CrO3 189.6 mg/L) are 202×, 79×, and 1459× greater than concentrations found within urban bumble bee collected provisions, respectively. Adult bumble bees fed field realistic concentrations of metals accumulate significant amounts of cadmium and lead within their bodies, but do not accumulate chromium and arsenic. Additionally, adults accumulate significantly higher concentrations of metals than brood. While bumble bee foragers are unlikely to encounter lethal metal concentrations while foraging in contaminated landscapes, it is crucial to consider and understand how sublethal concentrations impact overall colony functioning. The results from this study highlight the need to identify hazards and bioaccumulation ability of common metals as bees respond differently to each metal species, as well as the impacts of metal mixtures on bioaccumulation and toxicity.

Halide-mediated endogenous ZnO domain-confined etching strategy: Realizing superior potassium storage in carbon anode

Coupling sites of nitrogen-dopants and intrinsic carbon defects (N/DC) are highly attractive to improve potassium-storage capacity and cycling stability, yet it is hard to effectively construct them. Herein, a novel strategy is proposed to establish abundant N/DC sites in N-doped carbon (ZIF8/NaBr-1-900) by pyrolyzing the mixture of metal–organic framework (ZIF8)/sodium bromide (NaBr). Systematic investigations disclose that the introduced NaBr can promote the full conversion of Zn-N4 moieties into zinc oxide (ZnO) via a “bait and switch” mechanism. Such formed endogenous ZnO can etch the carbon matrix of the confined domains around the N dopants during pyrolysis process, and meanwhile the released N-atoms from Zn-N4 moieties can largely form edge-N. As such, these N/DC coupling sites enable the resultant carbon to have a more significant capacitive behavior related to fast K-ion migration and high structural stability, leading to 255.3 mAh/g at 2 A/g with a prolonged cycle lifespan over 2000 cycles. Moreover, the assembled K-full battery presents a high energy density of 171.2 Wh kg−1 and excellent cyclability over 5000 cycles. This NaBr-mediated endogenous ZnO domain-confined etching strategy provides a new insight into the exploration of advanced carbon anode.

Association between urinary multiple metals and platelet-related parameters: A cross-sectional study in a metal-contaminated area of China.

Previous works have shown that hematological system can be affected by exposure to lead; however, the effects of multiple metals on platelets remain elusive within the population from metal-contaminated areas. Hence, the study enrolled 609 participants, with 396 from a metal-exposed area and 213 from a control area. Platelet count (PLT), mean platelet volume (MPV), thrombocytocrit (PCT), platelet to large cell ratio (P-LCR), and platelet distribution width (PDW) were selected to evaluate platelet function. Stepwise regression and Lasso regression were utilized to identify the most influential metals. Moreover, the generalized linear model (GLM), Bayesian kernel machine regression (BKMR) models, and quantile g-computation were employed to estimate the individual or combined effects associations between 12 urinary metals and platelet indices. The results revealed all metals except vanadium, copper, strontium, and molybdenum were significantly higher in the exposed group. The GLM models indicated that urinary metals, including lead, antimony, and arsenic, exhibited associations with PLT, MPV, P-LCR, and PDW. Quantile g-computation and BKMR demonstrated negative correlations between metal mixtures and MPV as well as PDW. In conclusion, the study highlights the associations between multiple metal exposures and platelet indices, suggesting that elevated levels of the metal mixture may impede platelet activation in the population in metal-contaminated areas.

Influence of basalt fiber in ultra-high-performance concrete in hybrid mode: a comprehensive study on mechanical properties and microstructure

The end, in view of the research, is to effectively utilize natural fiber (basalt) to reinstate the mechanical strength lost by the ultra-high-performance concrete (UHPC) matrix when the metallic steel fibers are quantitatively curtailed. Also, the river sand is fractionally ousted from the mixture, and manufactured sand is substituted. In addition to the preliminary constituents of UHPC, nano silica was adopted for the adequate packing of the matrix, which aids in strength-gaining reaction as well. To induce sustainability and implement waste utilization, two different proportions using M-Sand were made with 30% and 4% replacement levels, and for each proportion of M-Sand, five different mixes were made for varying fiber incorporation. Including the control mix made without any fiber, a total of 12 mixes were made. Among the fibrous mixes, two were metallic fibrous mixtures, and the rest were hybrid fibrous mixtures, and inter-comparisons were done accordingly. The metallic fibers were added in 1% and 2%, and natural fibers were incorporated in 1%, 2%, and 3% in volumetric fractions. From the trial mixes it was identified that the inclusion of Basalt fibers of more than 3% resulted in reduced workability, and so the addition of basalt fibers was restricted to 3%. The water-to-binder ratio of the UHPC matrix ranged between 0.15 and 0.17, depending upon the dosage of fibers. High range water reducer (HRWR) was mixed with water during casting, to develop the workability. The specimens were tested for compressive strength, split tensile strength, and impact energy resistance. It was identified that the annexation of 1% steel and 3% basalt fibers with 30% M-Sand was effective as they showed better compressive strength and impact resistance than the other combinations. Further Scanning Electron Microscopic (SEM) imaging and Thermogravimetric Analysis (TGA), which were conducted, also validated the inference from the experimental investigations.The end, in view of the research, is to effectively utilize natural fiber (basalt) to reinstate the mechanical strength lost by the ultra-high-performance concrete (UHPC) matrix when the metallic steel fibers are quantitatively curtailed. Also, the river sand is fractionally ousted from the mixture, and manufactured sand is substituted. In addition to the preliminary constituents of UHPC, nano silica was adopted for the adequate packing of the matrix, which aids in strength-gaining reaction as well. To induce sustainability and implement waste utilization, two different proportions using M-Sand were made with 30% and 4% replacement levels, and for each proportion of M-Sand, five different mixes were made for varying fiber incorporation. Including the control mix made without any fiber, a total of 12 mixes were made. Among the fibrous mixes, two were metallic fibrous mixtures, and the rest were hybrid fibrous mixtures, and inter-comparisons were done accordingly. The metallic fibers were added in 1% and 2%, and natural fibers were incorporated in 1%, 2%, and 3% in volumetric fractions. From the trial mixes it was identified that the inclusion of Basalt fibers of more than 3% resulted in reduced workability, and so the addition of basalt fibers was restricted to 3%. The water-to-binder ratio of the UHPC matrix ranged between 0.15 and 0.17, depending upon the dosage of fibers. High range water reducer (HRWR) was mixed with water during casting, to develop the workability. The specimens were tested for compressive strength, split tensile strength, and impact energy resistance. It was identified that the annexation of 1% steel and 3% basalt fibers with 30% M-Sand was effective as they showed better compressive strength and impact resistance than the other combinations. Further Scanning Electron Microscopic (SEM) imaging and Thermogravimetric Analysis (TGA), which were conducted, also validated the inference from the experimental investigations.

Coaxial burner system for solid-sample flame emission spectroscopy.

We present a burner system to analyze solid, inflammable samples by flame emission spectroscopy without requiring any sample preparation procedures. An acetylene-nitrous oxide burner was designed to efficiently introduce solid particles into the flame through active injection, enabling real-time elemental analysis. Computational fluid dynamics (CFD) simulations were employed to study particle transport dynamics within the burner system. The emission was characterized through spectral analysis of the flame emission from copper- and iron-metal powder mixtures, demonstrating its ability to determine elemental compositions without prior sample treatment. An artificial neural network (ANN) was implemented to analyze spectral data obtained from binary Cu/Fe metal mixtures, enabling rapid and reliable identification of constituent elements with an uncertainty of σ = 2.7 mol%. The blackbody temperature could be determined in the range of 2200-2600 K with an accuracy of 7 K.

Prenatal Metal Exposures and Child Social Responsiveness Scale Scores in 2 Prospective Studies.

Prenatal exposure to metals is hypothesized to be associated with child autism. We aim to investigate the joint and individual effects of prenatal exposure to urine metals including lead (Pb), mercury (Hg), manganese (Mn), and selenium (Se) on child Social Responsiveness Scale (SRS) scores. We used data from 2 cohorts enriched for likelihood of autism spectrum disorder (ASD): Early Autism Risk Longitudinal Investigation (EARLI) and the Markers of Autism Risk in Babies-Learning Early Signs (MARBLES) studies. Metal concentrations were measured in urine collected during pregnancy. We used Bayesian Kernel Machine Regression and linear regression models to investigate both joint and independent associations of metals with SRS Z-scores in each cohort. We adjusted for maternal age at delivery, interpregnancy interval, maternal education, child race/ethnicity, child sex, and/or study site. The final analytic sample consisted of 251 mother-child pairs. When Pb, Hg, Se, and Mn were at their 75th percentiles, there was a 0.03 increase (95% credible interval [CI]: -0.11, 0.17) in EARLI and 0.07 decrease (95% CI: -0.29, 0.15) in MARBLES in childhood SRS Z-scores, compared to when all 4 metals were at their 50th percentiles. In both cohorts, increasing concentrations of Pb were associated with increasing values of SRS Z-scores, fixing the other metals to their 50th percentiles. However, all the 95% credible intervals contained the null. There were no clear monotonic associations between the overall prenatal metal mixture in pregnancy and childhood SRS Z-scores at 36 months. There were also no clear associations between individual metals within this mixture and childhood SRS Z-scores at 36 months. The overall effects of the metal mixture and the individual effects of each metal within this mixture on offspring SRS Z-scores might be heterogeneous across child sex and cohort. Further studies with larger sample sizes are warranted.

Bolivian natural zeolite as a low-cost adsorbent for the adsorption of cadmium: Isotherms and kinetics

Population growth in recent years has led to increased wastewater production and pollution of water resources. This situation also heavily affects Bolivia, so wastewater treatment methods and materials suitable for Bolivian society should be explored. This study investigated the natural Bolivian Zeolite (BZ) and its NaCl-modified structure (NaBZ) as adsorbents for cadmium removal from water. The natural BZ and the modified form NaBZ were investigated by different physicochemical characterization techniques. Furthermore, XPS and FT-IR techniques were used to investigate the adsorption mechanisms. The cadmium adsorption on BZ and NaBZ was analyzed using various mathematical models, and the Langmuir model provided a better description of the experimental adsorption data with cadmium adsorption capacities of 20.2 and 25.6 mg/g for BZ and NaBZ, respectively. The adsorption followed the pseudo-second order kinetics. The effect of different parameters, such as initial cadmium concentration and pH on the adsorption was studied. In addition, the results of the regeneration test indicated that both BZ and NaBZ can be regenerated by using hydrochloric acid (HCl). Finally, the adsorption experiment of BZ and NaBZ on a real water sample (brine from Salar de Uyuni salt flat) containing a mixture of different heavy metals was carried out. The results obtained in this study demonstrate the effectiveness of natural BZ and modified NaBZ in the removal of heavy metals from wastewater.

Heavy metals and trace elements in maternal blood and prevalence of congenital limb abnormalities among newborns: the Japan Environment and Children's Study.

Heavy metals such as lead (Pb) and cadmium (Cd) have been associated with adverse pregnancy and developmental outcomes, including congenital abnormalities. This study investigated the association between exposure to heavy metals and trace elements during fetal life and congenital limb abnormalities in infants. This study is based on a prospective ongoing nationwide birth cohort from the Japan Environment and Children's Study (JECS). The concentrations of Cd, Pb, mercury (Hg), selenium (Se), and manganese (Mn) were measured in maternal blood collected during the mid-late trimesters. Inclusion criteria were available from questionnaires filled in during pregnancy, including information about congenital limb abnormalities at birth or at one month. To examine the associations with limb anomalies and individual chemicals, logistic regression models were applied following log-transformation or division into quartiles of Cd, Pb, Hg, Se, and Mn concentrations. To assess the associations with the heavy metals and trace elements mixture, quantile g-computation was employed. All models were adjusted for age, maternal smoking history, maternal alcohol intake, history of smoking, and infant sex. Data from 90,163 participants were included in the analysis, of whom 369 had congenital limb abnormalities in any of the collected information, and 89,794 had none. Among the 369 cases of congenital limb abnormalities, there were 185 and 142 cases of polydactyly and syndactyly, respectively. The median concentrations of Pb, Cd, Hg, Se, and Mn were 5.85, 0.66, 3.64, 168, and 15.3 ng/g, respectively. There were no associations between maternal blood concentrations of Pb [adjusted odd ratio = 0.83; 95% confidence interval = 0.61, 1.11], Cd [0.87; 0.68, 1.10], Hg [0.88; 0.73, 1.07], Se [1.07; 0.44, 2.59], and Mn [0.91; 0.64, 1.30] with congenital limb abnormalities. No significant association was observed between the mixture of heavy metals and trace elements [0.85; 0.72, 1.02] and any congenital limb abnormalities. Moreover, there was no association with all polydactylies and all syndactylies, or any type of abnormality as a subdivision. At the maternal exposure levels of Cd, Pb, Hg, Se, and Mn assessed in the present study, no association was identified with the risk of developing congenital limb abnormalities in children.

Precursor- and waste-free synthesis of spark-ablated nanoparticles with enhanced photocatalytic activity and stability towards airborne organic pollutant degradation.

Photocatalyst synthesis typically involves multiple steps, expensive precursors, and solvents. In contrast, spark ablation offers a simple process of electrical discharges in a gap between two electrodes made from a desirable material. This enables a precursor- and waste-free generation of pure metal oxide nanoparticles or mixtures of various compositions. This study presents a two-step method for the production of photocatalytic filters with deposited airborne MnOx, TiO2, and ZnO nanoparticles using spark ablation and calcination processes. The resulting MnOx and TiO2 filters demonstrated almost twice the activity with outstanding performance stability, as compared to sol-gel MnO2 and commercial TiO2. The introduced method is not only simple, precursor- and waste-free, and leads to superior performance for the case studied, but it also has future potential due to its versatility. It can easily produce mixed and doped materials with further improved properties, making it an interesting avenue for future research.

Room temperature cost-effective synthesis of carbon quantum dots for fluorescence pattern recognition of metal ions.

Herein, a type of low-consuming carbon quantum dot (CD) has been synthesized at room temperature in just 45 minutes via Schiff base reaction between o-phthalaldehyde (OPA) and polyethyleneimine (PEI). These CDs are pH-dependent, so a novel label-free florescent sensor array can be constructed by utilizing buffers with various pH levels, which leads to distinctive fluorescence response patterns upon being challenged with metal ions for their pattern recognition. The results demonstrate that large-scale detection of metal ions can be achieved with as little as 3 types of sensors. Additionally, the sensors are able to discriminate between various metal ion concentrations and mixtures of different metal ions. The technique demonstrates potential uses in water quality monitoring by promising straightforward, quick, sensitive, and potent discrimination of metal ions.

Magnetic and injectable Fe-doped liquid metals for controlled movement and photothermal/electromagnetic therapy.

As a multifunctional material, gallium-based liquid metal (LM) mixtures with metal particles dispersed in the LM environment display many excellent and intriguing properties. In this study, biomaterials were prepared by mixing Fe particles with LM for easily manageable photothermal or electromagnetic therapy and evaluated. Clinically, the fabricated 5%Fe/LM sample was injectable and radiopaque, which allowed its smooth delivery through a syringe to the target tissues, where it could help achieve clear imaging under CT. Meanwhile, because of the loading of Fe particles, the 5%Fe/LM possessed a magnetic property, implying a high manipulation capability. According to the experiments, the capsule containing 5%Fe/LM when placed in an isolated pig large intestine could move as desired to the designated position through an external magnet. Further, the biosafety and low toxicity of the 5%Fe/LM were confirmed by cytotoxicity tests in vitro, and the temperature changes at the interface between the 5%Fe/LM and intestinal tissue after near-infrared (NIR) laser irradiation were determined through theoretical modeling and numerical simulation data analysis. Due to the excellent photothermal and magnetothermal effects of LM, the temperature of the 5%Fe/LM injected into the rabbit abdominal cavity could significantly increase under NIR laser or alternating magnetic field (AMF) administration. As a novel functional biomaterial, the 5%Fe/LM exhibited promising potential for designated position movement and photothermal or magnetothermal therapy in the near future.

Prosopis africana exerts neuroprotective activity against quaternary metal mixture-induced memory impairment mediated by oxido-inflammatory response via Nrf2 pathway.

The beneficial effects of Prosopis africana (PA) on human health have been demonstrated; however, its protective effects against heavy metals (HM) are not yet understood. This study evaluated the potential neuroprotective effects of PA in the cerebral cortex and cerebellum. To accomplish this, we divided 35 albino Sprague Dawley rats into five groups. Group I did not receive either heavy metal mixture (HMM) or PA. Group II received a HMM of PbCl2 (20 mg/kg), CdCl2 (1.61 mg/kg), HgCl2 (0.40 mg/kg), and NaAsO3 (10 mg/kg) orally for a period of two months. Groups III, IV, and V received HMM along with PA at doses of 500, 1000, and 1500 mg/kg, respectively. PA caused decreased levels of HM accumulation in the cerebral cortex and cerebellum and improved performance in the Barnes maze and rotarod tests. PA significantly reduced levels of IL-6 and TNF-α. PA increased concentrations of SOD, CAT, GSH, and Hmox-1 and decreased the activities of AChE and Nrf2. In addition, levels of MDA and NO decreased in groups III, IV, and V, along with an increase in the number of live neurons. In conclusion, PA demonstrates a complex neuroprotective effect with the potential to alleviate various aspects of HM-induced neurotoxicity.

Joint associations among non-essential heavy metal mixtures and nutritional factors on glucose metabolism indexes in US adults: evidence from the NHANES 2011-2016.

Dietary intake can modify the impact of metals on human health, and is also closely related to glucose metabolism in human bodies. However, research on their interaction is limited. We used data based on 1738 adults aged ≥20 years from the National Health and Nutrition Examination Survey 2011-2016. We combined linear regression and restricted cubic splines with Bayesian kernel machine regression (BKMR) to identify metals associated with each glucose metabolism index (P < 0.05 and the posterior inclusion probabilities of BKMR >0.5) in eight non-essential heavy metals (barium, cadmium, antimony, tungsten, uranium, arsenic, lead, and thallium) and glucose metabolism indexes [fasting plasma glucose (FPG), blood hemoglobin A1c (HbA1c) and homeostatic model assessment of insulin resistance (HOMA-IR)]. We identified two pairs of metals associated with glucose metabolism indexes: cadmium and tungsten to HbA1c and barium and thallium to HOMA-IR. Then, the cross-validated kernel ensemble (CVEK) approach was applied to identify the specific nutrient group (nutrients) that interacted with the association. By using the CVEK model, we identified significant interactions between the energy-adjusted diet inflammatory index (E-DII) and cadmium, tungsten and barium (all P < 0.05); macro-nutrients and cadmium, tungsten and barium (all P < 0.05); minerals and cadmium, tungsten, barium and thallium (all P < 0.05); and A vitamins and thallium (P = 0.043). Furthermore, a lower E-DII, a lower intake of carbohydrates and phosphorus, and a higher consumption of magnesium seem to attenuate the positive association between metals and glucose metabolism indexes. Our finding identifying the nutrients that interact with non-essential heavy metals could provide a feasible nutritional guideline for the general population to protect against the adverse effects of non-essential heavy metals on glucose metabolism.

Cross-sectional and prospective associations of early childhood circulating metals with early and mid-childhood cognition in the Project Viva cohort

BackgroundRelatively little is known about the immediate and prospective neurodevelopmental impacts of joint exposure to multiple metals (i.e., metal mixtures) in early childhood. ObjectivesTo estimate associations of early childhood (∼3 years of age) blood metal concentrations with cognitive test scores at early and mid-childhood (∼8 years of age). MethodsWe studied children from the Project Viva cohort. We measured erythrocyte concentrations of seven essential (Co, Cu, Mg, Mn, Mo, Se, and Zn) and eight non-essential metals (As, Ba, Cd, Cs, Hg, Pb, Sn, and Sr) in early childhood blood samples. Trained research assistants administered cognitive tests assessing vocabulary, visual-motor ability, memory, and general intelligence (standard deviations: ∼10 points), in early and mid-childhood. We employed multivariable linear regression to examine associations of individual metals with test scores adjusting for confounders, other concurrently measured metals, and first-trimester maternal blood metals. We also estimated joint associations and explored interaction between metals in mixture analyses. ResultsWe analyzed 349 children (median whole blood Pb ∼1 μg/dL). In cross-sectional analyses, each doubling of Pb was associated with lower visual-motor function (mean difference: −2.43 points, 95% confidence interval (CI): −4.01, −0.86) and receptive vocabulary, i.e., words understood (−1.45 points, 95% CI: −3.26, 0.36). Associations of Pb with mid-childhood cognition were weaker and less precise by comparison. Mg was positively associated with cognition in cross-sectional but not prospective analyses, and cross-sectional associations were attenuated in a sensitivity analysis removing adjustment for concurrent metals. We did not observe joint associations nor interactions. DiscussionIn this cohort with low blood Pb levels, increased blood Pb was robustly associated with lower cognitive ability in cross-sectional analyses, even after adjustment for prenatal Pb exposure, and regardless of adjustment for metal co-exposures. However, associations with mid-childhood cognition were attenuated and imprecise, suggesting some buffering of Pb neurotoxicity in early life. What this study addsRelatively few studies have comprehensively separated the effects of neurotoxic metals such as lead (Pb) from pre- and postnatal co-occurring metals, nor examined persistence of associations across childhood. In a cohort of middle-class children, we found higher early childhood (∼3 y) blood Pb was associated with lower scores on cognitive tests, independent of other metals and prenatal blood Pb. However, early childhood Pb was only weakly associated with cognition in mid-childhood (∼8 y). Our results suggest the effects of low-level Pb exposure may attenuate over time in some populations, implying the presence of factors that may buffer Pb neurotoxicity in early life.

(Invited) Enhanced Material Durability of Transition Metal-Antimony X-Ide Nanoparticles in Oxygen Reduction Electrocatalysis

Hydrogen fuel cells (FCs) are key energy devices that can accelerate our transition away from non-renewable, carbon-intensive fuels especially in the grid-scale storage and transportation sectors. FC cathodes perform the oxygen reduction reaction (ORR), and despite decades of progress towards higher performance electrocatalysts, the ORR remains kinetically sluggish and limits the efficiency of assembled FC devices. Modern, commercially available FC cathodes typically contain platinum (Pt)-based catalysts that can cause the overall FC to become prohibitively expensive for some applications so identifying alternate non-platinum group ORR catalyst formulations could increase deployment of FCs. Physics-based calculations with density functional theory (DFT) have predicted many first-row transition metal oxides (MOx, M = Mn, Fe, Cr, Ni, Co) as having favorable ORR performance trends. Additionally, there is experimental validation of nanoscale ternary and quaternary transition metal oxide systems with a mixture of transition metals used for catalyzing the ORR where relatively modest activity enhancements are reported. Despite this progress, an important limitation is present in the low material stability of non-precious transition metal oxides especially in acidic environments such as those encountered in proton exchange membrane FCs. Using synthetic material strategies to overcome such stability limitations in a variety of FC operating conditions will provide a deeper understanding of the relationship between structure, activity, and degradation.In this work, we employ two simultaneous strategies to work towards enhancing the activity and stability of transition metal oxides: (1) addition of antimony (Sb) as a ligand and (2) functionalization with nitrogen or sulfur. We utilized a previously reported colloidal synthesis for uniform ~ 50 nm oxide nanoparticles for manganese, nickel, cobalt, and iron to produce four sets of nanoparticles based on each of these metals. By using a colloidal synthesis that concurrently introduces Sb with the secondary metal and drying the particles afterwards, we incorporate Sb evenly throughout the polycrystalline structure of the of these nanoparticle catalysts. A high temperature surface modification reaction with reactive gas such as air, ammonia, or hydrogen sulfide was used to convert any remaining transition metal antimonate into an oxide, nitride, or sulfide, respectively. In total, twelve materials are used in this study: the oxide, nitride, and sulfide (collectively “X-ides”) of each of the four transition metal containing, antimony incorporated nanoparticles. We optimize this material synthesis and evaluate the nanoparticle catalyst’s ability to enhance electrochemical ORR activity in both acidic (pH 1) and alkaline (pH 13) conditions which are simulating operating conditions of proton-exchange membrane and anion-exchange membrane FCs, respectively. In addition to activity modulation, we measure the ORR selectivity change towards hydrogen peroxide formation for each material and note the role of nitrogen and sulfur modification in suppressing hydrogen peroxide formation in alkaline environments. In addition to electrochemical characterization, we employed a vast array of bulk and surface characterization techniques to understand catalyst dynamics and contextualize observed activity trends. Transmission electron microscopy (TEM) enabled determination of particle sizes and morphologies alongside electron diffraction patterns to validate the catalyst synthesis. X-ray diffraction (XRD) then provided further information about crystallinity that connected bulk-level insights to the local information from TEM. X-ray photoelectron spectroscopy (XPS) enabled determination of oxidation state changes in the transition metal and in Sb that serve as important descriptors for estimating the activity of these catalysts. We also employed in situ/operando techniques to probe catalyst dynamics and stability under various conditions. Using manganese K-edge synchrotron x-ray absorption spectroscopy (XAS) on the manganese antimony X-ides, we find significant changes to oxidation state and coordination of manganese in the nitride and sulfide as a function of potential indicating processes that displace nitrogen and sulfur in the lattice under certain conditions. Lastly, we use an in situ electrochemical flow cell coupled to inductively coupled plasma-mass spectrometry (ICP-MS) to measure corrosion as a function of ORR current density, potential sweeping, and electrolyte gas saturation to determine degradation patterns. Insights from all these techniques provide a fascinating perspective on what factors in a material and its environment are responsible for enhanced activity, selectivity, and stability. We perform DFT modeling of these systems to further elucidate material properties that are principally responsible for achieving key metrics in activity and stability especially as non-precious catalysts are evaluated for their performance in assembled device conditions. Combining electrochemical experiments, physics-based modeling, and material characterization to better understand structure-performance relationships is a promising path towards accelerating the process of materials discovery for eventual deployment in critical energy applications for the future.

Association of multiple blood metals and systemic atherosclerosis: A cross-sectional study in the CAD population

BackgroundCoronary atherosclerotic disease (CAD) is often accompanied by peripheral atherosclerosis, resulting in a higher risk of ischemia and cardiovascular death. Exposure to metals is associated with atherosclerotic plaques at specific sites. However, less is known about the effects of mixed metals on systemic atherosclerotic burden in CAD patients. ObjectivesTo investigate the association of metal mixtures with systemic atherosclerotic burden in a CAD population. MethodsA cross-sectional study including 1562 CAD patients from Southwest China was conducted. The levels of 10 blood metals were measured via inductively coupled plasma spectrometry. More than one vessel with a stenosis ≥50% vessel diameter was defined as CAD. Carotid and lower limb atherosclerosis was assessed by using ultrasound, and coronary atherosclerosis was quantified via arterial angiography. Systemic atherosclerosis was scored according to the presence or absence of lesions at the three sites and the total number of lesions. To investigate the combined impacts and interaction effects of metals, Bayesian kernel machine regression was used. Weighted quantile regression was used to identify the contributions of the metals. ResultsSignificant overall associations of mixed metals with systemic atherosclerotic burden were found. These positive overall associations were mainly driven by Cd, Cu and Pb in systemic atherosclerosis. The main contributing factors were As and Cu for coronary atherosclerosis as well as Cd, Cu and Pb for carotid and lower limb atherosclerosis. Cd and Pb or Cr can interact, and Pb interacts with age, sex and alcohol. ConclusionsIn CAD patients, exposure to combinations of metals was highly positively associated with systemic atherosclerotic burden. These significant trends were more pronounced in the peripheral arteries and carotid arteries. Controlling environmental metal exposure can contribute to reducing systemic atherosclerosis in CAD patients.