Cadmium (Cd) is a heavy metal toxic to the gut microbiome. In this study, we cultivated two human gut microbiomes (A and B) in bioreactors with Cd at 0 and 20 ppm for 7 days to investigate effects of ...Cd on the gut microbiome and to isolate Cd-tolerant bacteria autochthonous to the gut. Cd showed profound toxicity, abolishing butyrate production, depleting microbes in microbiome B, and simplifying microbiome A to a small Cd-tolerant community after 2 d of incubation. When spiked into the Cd-sensitive microbiome B, the Cd-tolerant community from microbiome A and isolates from that community worked synergistically with microbiome B to enhance butyrate production and maintained this synergism at Cd concentrations up to 5 ppm. Bacteria isolated from this Cd-tolerant community included Enterococcus faecium, Enterobacter cloacae, Lactococcus lactis, and Lactobacillus taiwanensis species. This work demonstrates a straightforward method for identifying Cd-tolerant bacteria autochthonous to the human gut that synergize with the microbiome to protect against Cd-related loss of butyrate production.
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•Human microbiomes differ in their susceptibility to Cd exposure.•Cd-tolerant bacteria were isolated from a complex microbiome using MiniBioreactors•Cd-tolerant bacteria protected a Cd-sensitive microbiome from Cd-related dysbiosis.
Hydrogen peroxide (H2O2) and heavy metals, which are among the wastes of the industrial sector, become a threat to living things and the environment above certain concentrations. Therefore, the ...detection of both H2O2 and heavy metals with simple, low-cost, and fast analytical methods has gained great importance. The use of nanoparticles in colorimetric sensor technology for the detection of these analytes provides great advantages. In recent years, green synthesis of nanomaterials with products that can be considered biowaste is among the popular topics. In this study, silver/silver chloride nanoparticles (Ag@AgCl NPs) were synthesized using the green synthesis method as an eco-friendly and cheap method, the green algae extract was used as a reducing agent. The characterization of Ag@AgCl nanoparticles and green algae extract was carried out with several techniques such as Transmission Electron Microscopy (TEM), UV–Visible spectrometry (UV–Vis), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction patterns (XRD) methods were used for characterization. According to TEM analysis, the Ag@AgCl NPs typically spherical in form and range in size from 4 to 10 nm, and UV–vis showed the formation of surface plasmon resonance (SPR) of the Ag@AgCl between 400 and 450 nm. In addition, its activity as a colorimetric sensor for hydrogen peroxide (H2O2) and multi-metal detection was evaluated. Interestingly, Ag/AgCl NPs caused different color formations for 3 metals simultaneously in the sensor study for heavy metal detection, and Fe3+, Cu2+, and Cr6+ ions were detected. The R2 values for H2O2, Fe3+, Cu2+, and Cr6+ were 0.9360, 0.9961, 0.9787, and 0.9625 the limit of detection (LOD) was 43.75, 1.69, 3.18, and 5.05 ppb (ng/mL), respectively. It was determined that Ag@AgCl NPs have the potential to be used as a colorimetric sensor for the detection of H2O2 and heavy metals from wastewater.
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•Ag/AgCl NPs was synthesized by green algae extract.•Current sensor detected the ions Cu2+, Cr6+, Fe3+, and H2O2.•With the naked eye, the change color was observed in the determination of Cu2+, Cr6+, and Fe3+ ions.
Heavy metal pollution in soil has emerged as a major environmental concern. This can be attributed to human activities such as mining, modern agriculture, and industrialization. This study was ...conducted to determine how heavy metals spread from mine tailings to surrounding farmland. Metal absorption and accumulation were also investigated in the root and shoot biomass of tapioca crops grown in those farmlands. Metal concentrations in MTAS1 were 85.3 ± 1.2, 45.8 ± 1.5, 134.8 ± 1.7, 92.4 ± 2.2, and 78.95 ± 1.4 mg kg-1, respectively. Heavy metal concentrations in MTAS2 and MTAS3 were found to be 79.62 ± 1.6, 75.4 ± 1.5, 41.31 ± 1.1, 47.8 ± 1.6, 142.5 ± 2.1, 128.4 ± 1.4, 86.2 ± 1.9, 79.5 ± 1.3, and 83.4 ± 1.2 mg kg-1, respectively. Tapioca crop shoot and root biomass grown at these metal polluted sites absorbed and accumulated significant amounts of Cd, Cu, Zn, Pb, Ni, and Mn. Notably, the metal content of the tapioca crop's root and shoot biomass exceeded national standards.
•Magnesite mine tailings dumped surrounding sites were polluted with heavy metals.•MTAS1, MTAS2, and MTAS3 farmland site was polluted with Cd, Cu, Zn, Pb, Ni, and Mn.•Root and shoot biomass of tapioca absorbed and accumulated these metals from polluted soil.•The metal was transferred from root to shoot of tapioca crop.
The objectives of the present study were to investigate heavy metal accumulation in 22 vegetable species and to assess the human health risks of vegetable consumption. Six vegetable types were ...cultivated on farmland contaminated with heavy metals (Pb, Cd, Cu, Zn, and As). The target hazard quotient (THQ) method was used to assess the human health risks posed by heavy metals through vegetable consumption. Clear differences were found in the concentrations of heavy metals in edible parts of the different vegetables. The concentrations of heavy metals decreased in the sequence as leafy vegetables > stalk vegetables/root vegetables/solanaceous vegetables > legume vegetables/melon vegetables. The ability of leafy vegetables to uptake and accumulate heavy metals was the highest, and that of melon vegetables was the lowest. This indicated that the low accumulators (melon vegetables) were suitable for being planted on contaminated soil, while the high accumulators (leafy vegetables) were unsuitable. In Shizhuyuan area, China, the total THQ values of adults and children through consumption of vegetables were 4.12 and 5.41, respectively, suggesting that the residents may be facing health risks due to vegetable consumption, and that children were vulnerable to the adverse effects of heavy metal ingestion.
Polymer electrolyte membrane (PEM) fuel cells or PEMFCs and PEM electrolysis cells or PEMECs are two closely related electrochemical devices having a similar structure: a PEM with catalyst layers ...(CLs) coated on its surfaces, flow fields, and bipolar plates (BPs). Both systems work at low temperatures (
e.g.
∼60-80 °C) and can operate free of CO
2
emissions. The PEMFC efficiency can reach as high as 65% with water as the only byproduct when using hydrogen as the fuel. PEMFCs have been considered for stationary, transportation, and portable applications. Several PEMFC products are commercially available, including back-up power and fuel cell electric vehicles (FCEVs). As of May 2021, over 10 000 FCEVs were sold or leased in the U.S. and 48 fuel cell electric buses (FCEBs) currently operate in California. More than 3520 FCEVs and 22 FCEBs were sold or leased in Japan up to 2020 and China has more than 6000 FCEVs. The cost and the lack of a hydrogen infrastructure are the two main barriers to the worldwide deployment of PEMFCs. Currently, a PEMFC stack costs about $75 per kW at high volume production and its CLs account for over 40% of the overall cost due to the employment of precious platinum-group metals (PGMs) as catalysts. For FCEVs to be competitive cost-wise, the ultimate goal is $30 per kW for light-duty FCEVs and $60 per kW for heavy-duty FCEVs. Another challenge that prevents FCEVs from widespread application is that only a few hundred hydrogen refueling stations (HRSs) are available in the world. To help overcome this challenge, Japan has set a target of building 320 stations by 2025 and 900 by 2030. Europe has a roadmap of achieving 1500 stations by 2025. China has over 40 HRSs and has been reported to have invested $17 billion dollars in hydrogen infrastructure. PEMECs operate in the reverse process of PEMFCs,
i.e.
hydrogen production through water splitting using electrical energy, and provide a promising source of renewable hydrogen to supply the fueling infrastructure. They have been successfully commercialized with power varying from a few kW to multiple MW and efficiency around 60-80%. As of 2019, over 14 MW of PEMECs have been installed or are underway across the U.S. The cost of producing hydrogen
via
PEMECs, which is currently at about $4-6 per kg, has been a limiting factor that prevents large-scale deployment and application. The U.S. DOE has recently set a target to achieve $1 per kg within one decade through the Hydrogen Shot initiative. The objectives of this review are three-fold: (1) to present the current status of PEMFC and PEMEC technologies and their ongoing development, along with the hydrogen infrastructure, (2) to describe the similarities and differences in PEMFC and PEMEC structures, materials, and fundamentals, and (3) to outline the major challenges and opportunities in the widespread deployment of PEMFCs and PEMECs and hydrogen infrastructure development.
This review presents the current status of PEM fuel cell & electrolysis cell technologies, along with the H
2
infrastructure, describes their similarities & differences in structures, materials, and fundamentals, and outlines challenges/opportunities.
Background and aims Cadmium (Cd) is a heavy metal that is highly toxic to organisms. Studies have shown that an increasing Fe supply decreases Cd accumulation in plants. In this study, we ...investigated the mechanism underlying the effect of Fe on Cd uptake. Methods We compared the effects of Fe application on Cd levels in wild-type Arabidopsis thaliana Col-0 and IRT1-null mutant irt1 (loss in function of Fe2+ uptake). Results In the Fe-Cd alternative rotation treatment, which ensured asynchronous uptake of Fe2+ and Cd2+, the irt1 mutants had a lower Cd level than the Col-0 plants. In addition, an increase in the Fe supply decreased the Cd level in Col-0 plants, accompanied by an inhibition of IRT1 expression in roots. Furthermore, both Col-0 and irt1 plants grown in Fe-Cd alternative rotation treatment, showed higher Cd uptake than those grown in another rotation treatment, which allowed synchronous uptake of Fe2+ and Cd2+. Nevertheless, the differences in Cd uptake between the two rotation treatments were greater in Col-0 plants than in irt1 mutants. Conclusions Inhibition of IRT1-mediated Cd uptake and enhancement of antagonism between Fe and Cd uptake are two mechanisms involved in the inhibition of Cd uptake by Fe supply
Facing the ever-growing demand for data storage will most probably require a new paradigm. Nanoscale magnetic skyrmions are anticipated to solve this issue as they are arguably the smallest spin ...textures in magnetic thin films in nature. We designed cobalt-based multilayered thin films in which the cobalt layer is sandwiched between two heavy metals and so provides additive interfacial Dzyaloshinskii-Moriya interactions (DMIs), which reach a value close to 2 mJ m(-2) in the case of the Ir|Co|Pt asymmetric multilayers. Using a magnetization-sensitive scanning X-ray transmission microscopy technique, we imaged small magnetic domains at very low fields in these multilayers. The study of their behaviour in a perpendicular magnetic field allows us to conclude that they are actually magnetic skyrmions stabilized by the large DMI. This discovery of stable sub-100 nm individual skyrmions at room temperature in a technologically relevant material opens the way for device applications in the near future.
Products used for hair care by humans are essential for cleaning, protection, perfuming, and beautification. These are applied directly on the skin and can be a potential factor for dermal exposure ...to toxic metals. The present research deals with the assessment of heavy metals in the hair care products available in the local markets of Karachi, Pakistan. A total of 20 brands of shampoo and 05 brands of conditioners were collected in triplicate and analyzed for 10 heavy metals (Fe, Mn, Cr, Ni, Cu, Co, Pb, Cd, Zn, and Hg) by atomic absorption spectrophotometer. Toxic metals were found to be higher in conditioner than in shampoo of respective color and brand. Ni and Zn concentrations have exceeded the maximum permissible limits. Consumers belonging to the lower class are more vulnerable to heavy metals exposure because of the high metal content in low-cost products. These results suggested that hair care products should also be considered as one of the sources of heavy metals exposure.
► Thiol-groups are successfully grafted on the surface of CNTs/Fe3O4 nanocomposites. ► Thiol-functionalized CNTs/Fe3O4 nanocomposites exhibit superparamagnetic property. ► A synthetic procedure for ...thiol-functionalized CNTs/Fe3O4 nanocomposites is proposed. ► The adsorption kinetics can be best described using pseudo-first-order kinetic equation. ► The adsorption isotherms match well with Langmuir model.
Thiol-functionalized multiwall carbon nanotube/magnetite nanocomposites (CNTs/Fe3O4) were synthesized, and were investigated by power X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometer, Fourier transform infrared spectroscopy, thermogravimetric analyses, BET analysis and physical properties measurement system. The results showed that the 3-mercaptopropyltriethoxysilane (MPTS) was successfully grafted on the surface of CNTs/Fe3O4 nanocomposites. The as-synthesized thiol-functionalized CNTs/Fe3O4 (MPTS-CNTs/Fe3O4) nanocomposites exhibited superparamagnetic property and higher specific surface area than that of CNTs/Fe3O4 nanocomposites at room temperature. The adsorption properties of Hg2+ and Pb2+ as a function of contact time, pH value and initial metal concentration were characterized by an inductively coupled plasma optical emission spectroscopy (ICP-OES). The pseudo-first-order kinetic equation could better than that of pseudo-second-order kinetic equation to describe the adsorption kinetics of the before and after thiol-functionalized nanocopmposites. The removal efficiency of CNTs/Fe3O4 nanocomposites and MPTS-CNTs/Fe3O4 nanocomposites was highly pH dependent and the optimal pH value for adsorption was 6.5. The adsorption isotherms of Hg2+ and Pb2+ by MPTS-CNTs/Fe3O4 nanocomposites matched well with the Langmuir model with the maximum adsorption capacities of 65.52 and 65.40mg/g, respectively.
Metakaolin based geopolymer (MKG) was investigated as an adsorbent to remove Zn(II) and Ni(II) ions from aqueous solution. The parameters of initial pH, adsorbent amount, time of contact and initial ...metal ion concentration on the metal removal performance of MKG were studied using a batch method at 25°C. The amount of Zn(II) and Ni(II) ions adsorbed onto MKG increased with increasing contact time with an adsorption equilibrium being reached within 40min and 50min for Zn(II) and Ni(II), respectively. The optimum values of initial pH were 6.39 for Zn(II) and 7.25 for Ni(II). The uptake of Zn(II) and Ni(II) ions by MKG was observed to decrease by increasing the adsorbent amount. The Langmuir isotherm described the adsorption data very well and the maximum monolayer adsorption capacities determined from the Langmuir adsorption isotherm were found to be 1.14×10−3 and 7.26×10−4molg−1 for Zn(II) and Ni(II), respectively. The kinetic studies showed that adsorption followed the pseudo-second-order kinetic model. The continuous mode adsorption studies showed the optimum flow rates were 2.0mLmin−1 for Zn(II) and 1.0mLmin−1 for Ni(II). The breakthrough points were observed at 150 and 280min for Zn(II) and Ni(II), respectively. It is concluded that Zn(II) and Ni(II) ions in aqueous solutions are efficiently removed by MKG which could be employed as a low-cost and excellent alternative for wastewater treatment.
•MKG displayed excellent good adsorption performance for Zn(II) and Ni(II).•Adsorption of Zn(II) and Ni(II) well fitted by the pseudo-second-order kinetics.•Adsorption of Zn(II) and Ni(II) takes place on the homogeneous surface of MKG.•MKG effectively removed Zn(II) and Ni(II) in continuous system.
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