Cr Concentration Research Articles

Response of oxidative stress and neurotoxicity biomarkers in rainbow trout (Oncorhynchus mykiss) after exposure to six-metal mixtures

ABSTRACT The activity of liver catalase and brain acetylcholinesterase was assessed in rainbow trout (Oncorhynchus mykiss) after 7- and 14-day exposure to a six-metal mixture at the maximum permissible concentrations accepted for inland waters in the EU (2013/39/EU; 2008/105/EC) (Zn − 0.1, Ni − 0.034, Cu − 0.01, Cr − 0.01, Cd − 0.0015 and Pb − 0.014 mg L−1) and to the same six-metal mixtures with tenfold reduced concentration of Cu and Cr ions. A statistically significant increase of up to 26% of catalase and 52% of acetylcholinesterase activity was observed in rainbow trout after 7 days of exposure to the six-metal mixture at the maximum permissible concentrations in comparison to a control group. After 14-day treatment, neither CAT nor AChE showed significant response to all tested metal mixtures. The six-metal mixture with the tenfold reduced concentration of Cr increased brain AChE activity in O. mykiss after 7 days of exposure (35%). Enhancement of catalase activity caused by the mixture of the six metals at the maximum permissible concentrations and the increased acetylcholinesterase activity in response to the same metal mixture and mixture with tenfold reduced Cr concentration after 7 days of exposure indicates the induction of oxidative stress and disturbance of cholinergic system homeostasis respectively.

Pollution Characteristics, Risk Assessment and Source Identification of Heavy Metals in Surface Sediments from the Cage Fish Farm of Poyang Lake, China

ABSTRACT With the development of cage culture, increasing heavy metals concentrations are being taken into sediments. The accumulation of heavy metals in sediments may cause long term environmental issues and pose threat to human health. Fourteen surface sediment samples were collected to assess the contamination status and potential ecological risk of heavy metals, and identify their potential sources from the cage fish farm of Poyang Lake. The concentrations of Cu, Pb, Zn, Cd, Cr, As and Ni in the sediments were measured by ICP-MS. The geo-accumulation index, enrichment factor and potential ecological risk index were implied to evaluate their pollution levels and ecological risk. The principal component analysis was used to identify their potential sources. The results showed that all of the examined heavy metals content exceeded their background values. These heavy metals (except Cd, Cr and As) presented moderately polluted level. Cu showed significant enrichment, Zn, Pb and Ni exhibited moderate enrichment, As and Cd presented minimal enrichment. Cu and Cd posed a moderate ecological risk, and the other heavy metals posed a low ecological risk. The comprehensive potential ecological risk was associated with considerable ecological risk. Cage culture, smelting, mining and agriculture activities were their primary pollution sources.

Risk factors for postoperative hepatic dysfunction in overweight patients with acute type A aortic dissection

BackgroundAcute hepatic dysfunction (AHD) is a common postoperative complication in patients with acute type A aortic dissection. The aim of this study was to identify risk factors for acute hepatic dysfunction after surgery for acute type A aortic dissection.MethodsWe performed a retrospective study from March 1, 2019, to February 28, 2021. The primary endpoints of this study were morbidity due to AHD and risk factors for incidence. Univariate analysis and multivariate logistic regression analysis were used to analyse the related factors, and receiver operating characteristic (ROC) curves were plotted to evaluate their predictive value.ResultsAmong 147 patients, 29 (19.73%) developed postoperative acute hepatic dysfunction, and 9 (6.12%) died. Univariate analysis revealed that the ALT (P = 0.042), Cr (P < 0.001), and BUN (P = 0.008) levels were significantly different between the two groups. Multivariate logistic regression analysis revealed that Cr (OR = 1.013, 95% CI = 1.003–1.023, P = 0.008) was an independent risk factor for postoperative hepatic dysfunction in overweight (BMI > 24) patients with ATAAD. The area under the ROC curve (AUC) for Cr was 0.745 > 0.7, indicating good predictive value.ConclusionA high Cr concentration is an independent risk factor for postoperative AHD in overweight (BMI > 24) patients with ATAAD.

Temperature dependence on γ/γ' partitioning behaviors of alloying elements and γ/γ' interfacial energy of a Mo-rich Ni based single crystal superalloy

Based on three-dimensional atom probe technique and Ardell method, the influences of temperature (850℃∼1150℃) on microstructure, compositions and solid solution strengths of γ and γ′ phases, γ/γ' partitioning behaviors of alloying elements and γ/γ' interfacial energy of a Mo-rich Ni based single crystal superalloy were investigated. After quenching from 1100℃, microstructure was basically similar as heat-treated state. However, after quenching from 1150℃, γ′ phase obviously re-dissolved, and γ channel obviously widened. Meanwhile, with increasing temperature, Co, Cr, Mo and Re contents in γ phase decreased, while Al and Ta contents in γ phase increased. With increasing temperature, Co, Cr and Re contents in γ′ phase slightly decreased, Mo content in γ′ phase significantly decreased, while Al and Ta contents in γ′ phase increased. Meanwhile, with increasing temperature, solid solution strength of γ phase decreased, while solid solution strength of γ′ phase increased. In addition, with increasing temperature, partitioning ratios of Co, Cr and Re elements decreased, partitioning ratios of Mo and Al elements increased, while partitioning ratio of Ta firstly decreased and then increased. Moreover, both γ/γ′ interfacial width and γ/γ′ interfacial energy decreased with increasing temperature.

Acute Effect of Three Aerobic Exercise Intensities on Glomerular Filtration Rate in Healthy Older Adults.

To assess the immediate effects of three aerobic exercise intensities on the estimated glomerular filtration rate (eGFR) in healthy, sedentary older adults. Eighteen healthy, sedentary older adults (ten men and eight women) voluntarily participated in this study. The participants underwent three standardized aerobic exercise tests (100%, 80%, and 60% of the maximal heart rate) on a bicycle ergometer. Blood samples were collected to determine cholesterol, triacylglycerols, glucose, serum creatinine (Cr), Cystatin C (CysC) concentrations, and eGFR. eGFR and serum concentrations of Cr and CysC were not modified at any exercise intensity. There was a negative correlation between blood total cholesterol vs. eGFR (R = -0.512, R = -0.582, R = -0.531; p < 0.05) at rest, 60%, and 100% of the maximal heart rate, respectively. In addition, a negative correlation existed for age vs. eGFR at 60% of the maximal heart rate (R = -0.516; p < 0.05). Short-duration aerobic exercise of low, moderate, and vigorous intensity did not significantly affect eGFR and is considered safe for kidney function in healthy, sedentary older adults. However, regular monitoring of kidney function in older people engaged in moderate- and high-intensity exercise is advised.

Bioaccumulation and health risks of chromium and cadmium in &lt;em&gt;Basella alba&lt;/em&gt; with emphasis on Urea, muriate of potash and triple super phosphate mixtures

Basella alba is a commonly consumed green leafy vegetable in South Asian countries and it is considered as an economical source of essential vitamins and dietary fibers. Urea, muriate of potash (MOP) and triple super phosphate (TSP) mixture is the most commonly used inexpensive fertilizer mixture in the commercial cultivation of B. alba. This study was conducted to assess the effect of using a mixture of Urea-MOP-TSP on the bioaccumulation potential of cadmium (Cd) and chromium (Cr) by the leaves of B. alba. Pots treated with the Urea-MOP-TSP mixture and compost were maintained in a greenhouse with controlled light and temperature settings. The concentrations of Cd and Cr in the root zone soil, roots and leaves of B. alba were analyzed using an Atomic Absorption Spectrophotometer after acid digestion. The health risk of consuming B. alba was evaluated using the daily intake of metals, health risk index and cancer risk index. The results showed that Cd and Cr can bioaccumulate in the leaves of B. alba. The bioaccumulation potential of Cr was higher than that of Cd. Although the daily intake of Cd and Cr from B. alba were below the maximum values stipulated by the WHO, the cancer risk index indicated potential cancer risks based on Cd intake due to consumption of B. alba cultivated using the Urea-MOP-TSP mixture. Furthermore, the health risks associated with the hyper-accumulation of Cd and Cr in the edible parts of B. alba cultivated using compost were significantly less compared to that of the plants treated with the Urea-MOP-TSP mixture. Therefore, if B. alba is cultivated using chemical fertilizer, it is recommended to regularly monitor the concentrations of Cd and Cr in the cultivation soil, chemical fertilizer and in the edible parts of B. alba to prevent the excessive buildup of Cd and Cr along the food chain. In addition, it is recommended to identify the potential microbial assemblages that can be inoculated to the cultivation soil to reduce the bioavailability of Cd and Cr.

Advanced Oxidation Technology Using Fe0/H2O2 as an effective treatment for recycling industrial wastewater for irrigation of Lolium perenne crops.

This study focused on developing a new Phenton treatment of water effluent coming from a local industrial estate and staining industry site. Different advanced oxidation technologies (AOTs) such as heterogeneous photocatalysis, Photo-Fenton and UV-Vis/H2O2 using FeSO4, and pure iron were evaluated. To develop this study, water samples were tested before and after each treatment. In general, after AOTs the amount of chlorides, nitrates, hydrocarbons, heavy metals, TOC and bacteria significantly decreased. Photo-Fenton and UV-Vis/H2O2/TiO2 showed the best performance in the treatment of staining industry and industrial wastewater, respectively. Photo-Fenton mineralized 100% of dyes, reduced by 99% total coliforms, eliminated 76% of TOC and 60% of heavy metals tested. Interestingly, use of iron metal in the Photo-Fenton treatment was found to achieve similar results. This means wastewater can be treated with benign chemicals. Treated wastewater was evaluated as a potential water source for the irrigation of Lolium perenne, a conventional crop in animal feed. In general, the physical characteristics of Lolium perenne such as leaf and roof length and width, were not significantly modified after irrigation with treated wastewater. Similar results were obtained using treated tap water as reference. A trace number of metals remaining from treatment was detected in grass and soil. However, the concentration of Cd, Cr, Cu, and Zn was very similar to tap water. Considering these outcomes, use of non-toxic zero valent iron metal and hydrogen peroxide in a Photo-Fenton reaction is a pilot plant scalable alternative oxidating treatment technology for recycling industrial wastewater in agricultural activities.Top of Form

Investigating electronic, linear and nonlinear optical characteristics of Cr-Substituted ZnS materials

The electronic, linear, and nonlinear optical (NLO) characteristics of the Cr-substituted ZnS (ZnCrS) materials are reported within density functional theory (DFT) by using the mBJ potential. The results showed a cubic symmetry with a lattice constant decreasing as the Cr concentration increased, but the bulk modulus showed the opposite tendency. ZnS is a direct wide bandgap semiconductor; however, incorporating 75 % Cr in the ZnCrS materials causes a change in electronic bandgap nature. This change occurs due to Cr-induced defects and structural modifications, leading to new electronic transitions yielding novel optical features. The electronic and optical bandgap energy decreases with Cr content, depicting CrS as a semi-metallic material with significant light absorbance in the near-infrared and visible wavelengths accompanying the enhancement of the NLO response. It is noticed that a decrease in Εopt significantly impacted the NLO response, resulting in a significant change in the value of third-order susceptibility (χ(3)) from 5.862 × 10−11 to 2.074 × 10−9 esu. The NLO refractive index (n2) also follows the same changing trend, varying from 5.113 × 10−11 to 1.735 × 10−8 esu. This Cr-induced nonlinearity depicts strong polarizability and these materials can be significantly employed in near-infrared activated nanophotonic, photovoltaic, and optoelectronic devices.

Selective electro-induced reduction using bionic BC@SA-Nafion particle electrodes in 3D systems and phytotoxicity assessment

Three-dimensional electrode technology (3D technology), featuring dispersed particulate electrodes is rapidly advancing in the separation of pollutants. However, in contrast to the electrochemical oxidation performance, the design of particulate electrodes for electrochemical reduction remains relatively underexplored. This study introduced a bionic particle electrode (BC@SA-Nafion) with high reducibility and selectivity, and integrated it into a 3D system. Specifically, the selective electro-induced reduction capacity of BC@SA-Nafion was examined using Cr(Ⅵ) as a model pollutant. The electrochemical reactivity of BC@SA-Nafion was found to be dependent on the amount of biochar (BC) incorporated. Furthermore, the selectivity for Cr(Ⅵ) could be fine-tuned by adjusting the Nafion content, thereby addressing the efficiency decline at lower Cr(Ⅵ) concentrations. In the 3D system, the Cr(Ⅵ) removal rate reached up to 99 % under optimal conditions (pH 2, 2 V cm−1, 30 min). The density functional theory calculations indicated that the selectivity of BC@SA-Nafion for Cr(Ⅵ) was dependent on the presence of fluorine bonds. The reduction of Cr(Ⅵ) mainly relied on direct electron transfer provided, with superoxide (·O- 2) also playing a role. Post-treatment with the 3D technology resulted in negligible phytotoxicity of the wastewater. This study introduced a novel strategy for enhancing the selectivity of particle electrodes, thereby expanding the application of the particle electrode and advancing sustainable water treatment technologies.

Utilizing a medicinal plant and soil assays for heavy metal pollution assessment and its impacts in a Turkish Industrial Zone

Due to the worldwide growth in population, agricultural and industrial activities are expanding quickly, which pollutes the air, water, and soil and leads to the buildup of potentially hazardous substances in medicinal plants. The current study sought to determine the concentrations of various metals in Silybum marianum plants and soils in order to highlight the level of pollution in a Turkish Organized Industrial Zone in Dilovasi District, Kocaeli, and to investigate the effects of these heavy metals on plants. In order to determine the concentrations of elements evaluated within the scope of this study inductively coupled plasma optical emission spectroscopy was employed, due to the benefits of ICP that provides few or no organic molecules, few ionization interferences, as well as the ability to analyze many elements sequentially. Furthermore, in order to evaluate elemental analysis in terms of nutritional values, risk assessments using RDA, EDI, THQ, and HI parameters were conducted. The value of heavy metals in co-located soil samples is relatively high. However, except for Co, Mn, and Ni, it has stayed within the World Health Organization’s permitted limits. The evaluation of the co-located soil samples found that the highest contents (mg kg−1) of Al, Ca, Cd, Cr, Cu, Fe, K, Mn, Na, Ni, Pb, and Zn, were recorded as 7825.10, 4365.86, 4768.59, 2.50, 30.45, 38.49, 8352.00, 17452.26, 1495.82, 1495.82, 163.53, 1452.23, 28.67, 136.55 and 125.45, respectively, belonging to Location 1. These findings are in accordance with the Industrial Status Report since the place specified as Location 1 in the current study is characterized by its pronounced industrial activity and the robust electrical plant station with an industrial facility for generating electric power. Furthermore, the hazard index, the estimated daily intake and target hazard quotient for potentially harmful components and recommended daily allowance values for mineral nutrients were computed. Therefore, even though mineral nutritional values in some areas were found to be higher than Buyukada control location, this should be ignored. Consequently, this study warns against using S. marianum plants as food or medicine collected from current regions. As a result, ongoing inspection is necessary to prevent an excessive buildup of metals in the area and other places with similar human life-related features.

Pollution of Heavy Metals in Topsoil of Remote Mountainous Areas in Western Yunnan-Guizhou Plateau

Heavy metals from anthropogenic emissions have had a negative impact on the ecological environment in remote regions. A total of 69 topsoil samples were collected from 13 remote mountainous areas in the western Yunnan-Guizhou Plateau at altitudes of 2 563-4 037 m, and the concentrations of ten heavy metals in the samples were determined. Enrichment characteristics and pollution sources of heavy metals in topsoil were discussed by referencing the enrichment factor （EF）, positive matrix factorization （PMF）, and Pb isotopes. The results showed that the average concentrations of Al, Fe, Cu, V, and Zn in the topsoil were lower than the soil background values in Yunnan Province； the average concentrations of Ni and Pb were similar to the background values； and the average concentrations of Cd, Cr, and Hg were 1.8-3.6 times higher than the background values. The average EF values of Pb, Cr, and Ni were 3.8, 3.4, and 2.3, respectively, showing moderate enrichment according to the EF classification criteria； the average EF values of Cd and Hg were 15.2 and 10.0, reflecting significant enrichment； and the average EF values of the other metals ranged from 1.1 to 1.9, displaying none-weak enrichment. Combining the comparisons of heavy metal concentrations and ratios in topsoil and bedrock and the EF and PMF results, Al, Fe, V, Cr, Cu, Ni, and Zn in topsoil were considered primarily from detrital sources, and the spatial concentration variations of the metals should have been mainly regulated by the parent material. Cadmium, Hg, and Pb were obviously polluted by anthropogenic emissions, and the main sources were non-ferrous metal smelting and coal combustion. The areas with relatively high Cd, Hg, and Pb pollution were mainly distributed in the Jiaozi snow mountain, Bitahai watershed, Luoji Mountain, and Laojun Mountain areas. Anthropogenic emissions contributed 23.8% of the accumulation of heavy metals in the topsoil.

Characteristics, Source Apportionment, and Health Risk of Heavy Metals in the Soils of Peri-urban Shanghai Chongming Island.

Heavy metals resulting from human activities pose significant threats to human health and the soil ecosystem. In the current study, 917 soil samples from Chongming Island in Shanghai, China, were examined for eight heavy metals. The sources of contamination were identified by using a Positive Matrix Factorization (PMF) model. Meanwhile, spatial interpolation and Moran's I index were applied to validate the model in terms of spatial linkages. The results revealed that the average concentrations of As, Cd, Hg, Pb, Cr, Cu, Zn, and Ni in the soil were 8.87, 0.19, 0.06, 28.75, 76.01, 37.74, 88.93, and 30.33 mg kg-1, respectively. The PMF analysis proved that heavy metals in the soil of the study area are mainly influenced by traffic sources (Cr and Pb), industrial sources (Zn, Cd, and Cu), station sources (Hg), and natural sources (As and Ni), with contribution rates of 22.23, 26.25, 36.38, and 15.14%, respectively. The combination of Moran's index and the spatial analysis method not only verified the analytical results of the receptor model on the one hand but also served as a supplementary explanation for the sources of heavy metals in the soil. The health risk assessment indicated that noncarcinogenic values were below the threshold values. The total carcinogenic risk (R T) of different heavy metals has a descending order of Cr > As > Ni > Cd. The R T values of multiple heavy metals for children and adults were 5.28 × 10-04 and 4.10 × 10-05, respectively, which were close to the risk threshold. Therefore, attention should be paid to the health risks, especially for children's skin contact, which is the main exposure pathway.

Spatial and temporal mush heterogeneity during eruptions recorded in clinopyroxene from the 2021 paroxysms at Mt. Etna, Italy

Textural and compositional zoning of volcanic minerals archives pre-eruptive magma processes. Crystals erupted simultaneously may be sampled from different regions of the plumbing system and hence record variable histories due to complex magma dynamics. In addition, crystals erupted throughout the course of an eruption may record temporal variations in the plumbing system. To resolve mush variability on both spatial and temporal scales, we investigate clinopyroxene erupted during a series of paroxysmal episodes between February–April 2021 at Mt. Etna, Italy. Using a combination of high-resolution geochemical techniques, we observe that Cr enrichments in clinopyroxene mantle zones, grown upon eruption-triggering mafic rejuvenation, exhibit both temporal and spatial (sample-scale) variability. Temporal variability correlates with changes in glass compositions, attesting to the ability of clinopyroxene to track magma maficity throughout an eruption. Spatial variability, indicated by the scatter of Cr concentrations, is greatest for the first event and lowest for the final paroxysm. In conjunction with core textures, degree of sector enrichment and thermobarometry, our data suggest that the onset of the paroxysms was preceded by the remobilisation of a mid-crustal clinopyroxene mush (534 ± 46 MPa) by hot, mafic magma causing variable resorption of mush-derived crystal cores. Towards the end of the eruption, waning magma supply led to less efficient mush remobolisation and mixing, resulting in homogenous crystal populations. Our results highlight that clinopyroxene Cr contents and sector enrichment can be used to track mafic rejuvenation and magma evolution throughout eruptions, while also reflecting spatial heterogeneities within the plumbing system.

Ecological risk assessment of heavy metals contaminated mining sites of eastern india using soil and moss.

The blooming industrialization and urbanization is leading to increased mining operations. These intensified mining activities emit heavy metals into the environment, posing serious threats to ecosystems. Hence, this study focused on assessing heavy metal pollution in mining soil, utilizing mosses as bioindicators. The ecological risk, geo-accumulation factor, and contamination factor have been calculated to know the harmful effect of heavy metals on ecosystem. The study covered three distinct mining sites of eastern India within Odisha: Jajpur's Sukinda Valley (SP1, Cr), Keonjhar's Joda-Barbil (SP2, Fe and Mn), and Sundargarh's Koira-Joda (SP3, Fe). The collection of 48 soil samples through random sampling revealed significant variations in heavy metal concentrations. SP1 recorded Cr concentration of 6572 ± 445mg/kg and Ni of 8042.47 ± 501.38mg/kg, surpassing eco-toxicological levels. The storage site in SP2 exhibited the highest Fe concentration at 9872 ± 502mg/kg, and Mn levels in SP3 were at 7884 ± 432mg/kg. Storage areas in all three regions held the highest concentrations of heavy metals. Mosses in studied area demonstrated as potential bioindicators for monitoring heavy metal pollution. EF and Igeo assessments showed Cd, Pb, Hg, and other heavy metal contamination compared to earlier investigations. This study indicated higher ecological risks for Pb, As, Cu, Ni, and Zn. The Hyophila involuta accumulates Mn, Cr, Cd, Pb, Fe, and Hg, while Barbula arcuata accumulates Mn, As, and Cu in SP1. Hyophila involuta and Trematodon longicollis accumulate Mn, Cr, Cd, Pb, Fe, Hg, and Zn in SP2. Trematodon ambiguous accumulates Cd, Fe, and Ni, while Fissidens diversifolius accumulates Mn, Cr, Hg, As, Cu, and Zn in SP3. These findings emphasize the necessity of monitoring heavy metal pollution in contaminated zones using moss as a potential bioindicator.

Harnessing Moringa oleifera root powder (MORP) for the sustainable remediation of heavy metal contaminated water.

Heavy metal environmental pollution is rapidly increasing due to the increase in industrialization and urbanization. Industrial processes, such as paint production, mining, and raw materials producing industries release effluents rich in heavy metals, like Pb2+, Cd2+, Cu2+, and Cr3+. These heavy metals are dangerous because they persist in nature, are non-biodegradable and they have high tendency to accumulate in the environment and in living organisms who are exposed to them. This work studied the removal of heavy metals (Cu, Pb, Cr, and Cd) from aqueous solution using Moringa oleifera root powder (MORP) as the adsorbent. The MORP was characterized by SEM, FTIR, BET, and XRD. Batch adsorption experiments carried out investigated the effects of adsorbate concentration, adsorbent dosage, agitation time, pH and temperature on adsorption. The optimum parameters are: contact time (90 min); pH (9); adsorbent dose (0.6); metal ion concentration (30 mg L-1) for Cr and 40 mg L-1 for the rest; and temperature (50 °C) for Cu and Pb, and 70 °C for Cr and Cd. These experimental data were analyzed with 5 isotherm models (Temkin, Flory-Huggins, Langmuir, D-R and Freundlich). The result obtained fitted best to Temkin isotherm in comparison to others. Kinetic studies revealed that the pseudo-second order kinetic model best described the adsorption (with high R2 values ranging from 0.9810-0.9976) compared to pseudo-first order and intra-particle diffusion kinetics model. Results of the thermodynamic study showed that the sorption process was endothermic for Cu and Pb, but exothermic for Cd and Cr. The adsorbent showed good adsorptive tendencies toward the ions studied, and could be applied on an industrial scale for the remediation of metal contaminated water.

Adsorption Study for Chromium (VI) on Iraqi Bentonite

The subject of this research involves studying adsorption to remove hexavalent chromium Cr(VI) from aqueous solutions. Adsorption process on bentonite clay as adsorbent was used in the Cr(VI) concentration range (10-100) ppm at different temperatures (298, 303, 308 and 313)K, for different periods of time. The adsorption isotherms were obtained by obeying Langmuir and Freundlich adsorption isotherm with R2 (0.9921-0.9060) and (0.994-0.9998), respectively. The thermodynamic parameters were calculated by using the adsorption process at four different temperatures the values of ?H, ?G and ?S was [(+6.582 ? +6.547) kJ.mol-1, (-284.560 ? -343.070) kJ.mol-1 and (+0.977 ? +1.117) kJ.K-1.mol-1] respectively. This data indicates the spontaneous sorption process. The kinetic study of adsorption process was studied depending on three kinetic equations: 1- Lagergren equation 2- Morris-Weber equation 3- Reichenberg equation

Effect of Cr content on the high temperature oxidation behavior of FeCoNiMnCrx porous high-entropy alloys

FeCoNiMnCr porous high-entropy alloys were prepared using the activation reaction sintering method with Fe, Co, Ni, Mn, and Cr as raw materials. The oxidation behaviors of FeCoNiMnCrx porous high-entropy alloys with different Cr contents, such as pore structure, the surface oxide film phase composition, structure, and morphology, were characterized by X-ray diffraction (XRD), electron probe micro analysis (EPMA), energy dispersive X-ray spectroscopy (EDS), and pore tester after high-temperature oxidation at 800–1000 °C. The results indicate that the initial porous high-entropy alloy comprises a single FCC solid solution phase. With the increase in Cr content, the average pore diameter, average porosity, and air permeability of the porous high-entropy alloy also increase. The oxidation kinetics of the porous high-entropy alloy after exposure to temperatures between 800 °C and 1000 °C follows a single-stage parabolic evolution law. At the same oxidation temperature, With the increase of Cr content, the oxidation gains gradually increased, at the same Cr content at different temperatures, the antioxidant performance of 1000 °C was the weakest, followed by 800 °C, and 900 °C showed excellent antioxidant performance. The oxidation products are mainly Mn2O3, Mn3O4, (Mn, Cr)3O4, Cr2O3and Fe2O3.

Development of a novel method based on extraction mediated by a semipermeable membrane to determine Cd and Cr in sugar by graphite furnace atomic absorption spectrometry

This work proposes a novel method to determine the Cd(II) and Cr(III) content in commercial sugar samples. It is based on the extraction of the analytes (as ammonium pyrrolidine dithiocarbamate complexes) into a semipermeable membrane device (SPMD) filled with CHCl3. After extraction, the SPMD was deployed and opened, and the analytes were recovered from the organic phase by back extraction with a 4.2 mol L−1 HNO3 solution. The analytes present in the acid extract were measured with graphite furnace atomic absorption spectrometry. Under optimized conditions, the limit of quantification of the method was 1.2 and 3.1 ng g−1 for Cd(II) and Cr(III), respectively. Twelve samples of different types of sugar were analyzed. In addition, a recovery test was performed to evaluate the accuracy of the method. The recovery percentage was 90 %–102 % for Cd(II) and 85.2 %–103 % for Cr(III).

B-277 Detectable Levels of Toxic Metals in Children's Playgrounds

Abstract Background Metal-contaminated soil poses significant health risks to kids because they are more sensitive to heavy metal exposure in the environment. Studies have shown that continuous exposure to metals can increase the risk of metal accumulation in blood and various body organs. This study determines the levels of some toxic metals in various playgrounds in our community. Methods We determined the levels of lead (Pb), chromium (Cr), cadmium (Cd), and copper (Cu) in six playgrounds (parks) (T-RP, T-GP, T-TX, L-HH, L-WH, L-SPLX) using graphite furnace atomic absorption spectrophotometry (GF-AAS) technique. Soil samples were collected at least one foot below the soil surface, and metal was extracted using ultra-pure nitric before analysis using GF-AAS. Data were analyzed using analysis of variance (ANOVA). Results The results showed significant detectable levels of the metals in all playgrounds evaluated in this study. L-WH Park in League City has the highest detectable levels of Pb (12.43 ± 46 mg/Kg, P&amp;lt;0.05) compared to other children playgrounds examined in this study (T-RP (3.93 ± 3.97 mg/Kg), T-GP (7.09 ± 2.79 mg/Kg), T-TX (6.05 ± 1.92 mg/Kg), L-HH (4.68 ± 0.76 mg/Kg), L-SPLX (2.64 ± 1.63 mg/Kg). The concentration of detectable cadmium in T-RP park (0.16 ± 0.11 mg/Kg) was significantly higher than all the other five children's playgrounds studied L-WH (0.02 ± 0.01 ), T-GP (0.05 ± 0.04 mg/Kg), T-TX (0.02 ± 0.01 mg/Kg), L-HH (0.04 ± 0.01 mg/Kg), L-SPLX (0.09 ± 0.04 mg/Kg) (P&amp;lt;0.05). Conclusions The playgrounds contain detectable toxic metals that might pose health risks to children in the community. Though the lead levels are below the CDC-recommended lead soil concentration in urban areas, they still pose health risks to children in the environment when continuously exposed to the playground. The concentrations of Cu and Cr were not statistically different among the playgrounds. The detection of Pb and Cd highlights the potential health risks to children. Overall, this study shows that metal levels in playgrounds should be public information available to parents.

Variation of the Passive Film on Compositionally Concentrated Dual-Phase Al0.3Cr0.5Fe2Mn0.25Mo0.15Ni1.5Ti0.3 and Implications for Corrosion

AbstractThe passive film on a dual-phase Al0.3Cr0.5Fe2Mn0.25Mo0.15Ni1.5Ti0.3 FCC + Heusler (L21) compositionally concentrated alloy formed during extended exposure to an applied potential in the passive range in dilute chloride solution was characterized. Each phase, with its own distinct composition of passivating elements, formed unique passive films separated by a heterophase interface. High-resolution, surface sensitive characterization enabled chemical analysis of the passive film formed over individual phases. The film formed over the L21 phase had a higher concentration of Al, Ni, and Ti, while the film formed over FCC phase was of similar thickness but contained comparatively higher Cr, Fe, and Mo concentrations, consistent with the differences in bulk microstructure composition. The passive film was continuous across phase boundaries and the distribution of passivating elements (Al, Cr, and Ti) indicated both phases were independently passivated. Spatially resolved analysis of the surface chemistry of the dual-phase CCA revealed that the cation with the highest composition in passive film formed on the FCC phase was Cr (52.4 at. pct) and for the L21 phase was Ti (53.1 at. pct) despite the bulk concentration of each element being below 20 at. pct in their respective phases. Al, Cr, and Ti were enriched in both phases within the passive film relative to their respective bulk compositions. In parallel studies, single-phase alloys with compositions representative of the FCC and L21 phases were synthesized to evaluate the corrosion behavior of each phase in isolation. The corrosion behavior of the dual-phase alloy showed passivity evidenced by a pitting potential of 0.615 VSCE in 0.01 M NaCl. The pitting potential and other electrochemical parameters suggested a combination of behaviors of both single-phase samples, suggesting that the global corrosion behavior may be represented by a composite theory applied to phases, their area fractions, and interphase length. However, the interphase in the dual-phase CCA was a local corrosion initiation site and may limit localized corrosion protectiveness. The alloy design implications for optimization of second phase structure and morphology are discussed.