High Concentrations Of Cobalt Research Articles

The metal-binding GTPases CobW2 and CobW3 are at the crossroads of zinc and cobalt homeostasis in Cupriavidus metallidurans.

The metal-resistant beta-proteobacterium Cupriavidus metallidurans is also able to survive conditions of metal starvation. We show that zinc-starved cells can substitute some of the required zinc with cobalt but not with nickel ions. The zinc importer ZupT was necessary for this process but was not essential for either zinc or cobalt import. The cellular cobalt content was also influenced by the two COG0523-family proteins, CobW2 and CobW3. Pulse-chase experiments with radioactive and isotope-enriched zinc demonstrated that both proteins interacted with ZupT to control the cellular flow-equilibrium of zinc, a central process of zinc homeostasis. Moreover, an antagonistic interplay of CobW2 and CobW3 in the presence of added cobalt caused a growth defect in mutant cells devoid of the cobalt efflux system DmeF. Full cobalt resistance also required a synergistic interaction of ZupT and DmeF. Thus, the two transporters along with CobW2 and CobW3 interact to control cobalt homeostasis in a process that depends on zinc availability. Because ZupT, CobW2, and CobW3 also direct zinc homeostasis, this process links the control of cobalt and zinc homeostasis, which subsequently protects C. metallidurans against cadmium stress and general metal starvation.IMPORTANCEIn bacterial cells, zinc ions need to be allocated to zinc-dependent proteins without disturbance of this process by other transition metal cations. Under zinc-starvation conditions, C. metallidurans floods the cell with cobalt ions, which protect the cell against cadmium toxicity, help withstand metal starvation, and provide cobalt to metal-promiscuous paralogs of essential zinc-dependent proteins. The number of cobalt ions needs to be carefully controlled to avoid a toxic cobalt overload. This is accomplished by an interplay of the zinc importer ZupT with the COG0523-family proteins, CobW3, and CobW2. At high external cobalt concentrations, this trio of proteins additionally interacts with the cobalt efflux system, DmeF, so that these four proteins form an inextricable link between zinc and cobalt homeostasis.

Uric acid mediates the relationship between mixed heavy metal exposure and renal function in older adult people

BackgroundPopulation aging is a pivotal trend observed globally, and the exposure to heavy metals can exacerbate the aging process and lead to kidney damage. However, the impact of combined heavy metal exposure on renal function among older individuals remains elusive. Our study employs machine learning techniques to delve into the effects and underlying mechanisms of mixed exposure to heavy metals on the renal function of the aging population.MethodsThis study extracted comprehensive data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2015 and 2020. A total of 3,175 participants aged 60 years and above, with complete information on six metals – lead, cadmium, manganese, cobalt, mercury, and selenium, along with relevant covariates, were included in the study. To assess the impact of single or mixed metal exposure on the renal function of older adult individuals, various statistical techniques were employed: multiple logistic regression, weighted quantitative sum (WQS) regression, Bayesian kernel machine regression (BKMR), and mediation effects analysis.ResultsMultiple logistic regression revealed that selenium and manganese were protective factors for chronic kidney disease (CKD). Cobalt was a risk factor for CKD. High concentrations of lead, cadmium, and cobalt were risk factors for urinary albumin creatinine ratio (ACR). WQS analyses revealed that mixed metal exposure was positively correlated with estimated glomerular filtration rate (eGFR) but negatively correlated with CKD. Selenium and manganese can neutralize the effects of other metals on eGFR. Mixed metal exposure was positively correlated with ACR, with lead and cadmium having a substantial effect. Mediation analysis showed that uric acid (UA) had a mediating effect of 9.7% and −19.7% in the association between mixed metals exposure and proteinuria and CKD, respectively.ConclusionThe impact of heavy metals on renal function in the older adult differs from that of adolescents and adults. This study suggests that elevated levels of mixed metals exposure are linked to proteinuria and CKD, with UA serving as a mediating factor.

A bioprocess engineering approach for the production of hydrocarbons and fatty acids from green microalga under high cobalt concentration as the feedstock of high-grade biofuels

Botryococcus braunii, a colonial green microalga which is well-known for its capacity to synthesize hydrocarbons, has significant promise as a long-term source of feedstock for the generation of biofuels. However, cultivating and scaling up B. braunii using conventional aqua-suspended cultivation systems remains a challenge. In this study, we optimized medium components and light intensity to enhance lipid and hydrocarbon production in a multi-cultivator airlift photobioreactor. BBM 3N medium with 200 μmol/m2/s light intensity and a 16 h light–8 h dark regimen yielded the highest biomass productivity (110.00 ± 2.88 mg/L/day), as well as the highest lipid and hydrocarbon content. Cultivation in a flat-panel bioreactor resulted in significantly higher biomass productivity (129.11 ± 2.74 mg/L/day), lipid productivity (32.21 ± 1.31 mg/L/day), and hydrocarbon productivity (28.98 ± 2.08 mg/L/day) compared to cultivation in Erlenmeyer flasks and open 20-L raceway pond. It also exhibited 20.15 ± 1.03% of protein content including elevated levels of chlorophyll a, chlorophyll b, and carotenoids. This work is noteworthy since it is the first to describe fatty acid and hydrocarbon profiles of B. braunii during cobalt treatment. The study demonstrated that high cobalt concentrations (up to 5 mg/L of cobalt nitrate) during Botryococcus culture affected hydrocarbon synthesis, resulting in high amounts of n-alkadienes and trienes as well as lipids with elevated monounsaturated fatty acids concentration. Furthermore, pyrolysis experiments on microalgal green biomass and de-oiled biomass revealed the lipid and hydrocarbon compounds generated by the thermal degradation of B. braunii that facilitate extra economical value to this system.

Eco-Friendly Remediation: Tea Leaves and Fibres as Adsorbents for High Cobalt Concentrations; Thermodynamics, Isotherms and Kinetic Studies

Increasing industrialization has produced huge amounts of liquid effluents, which are a key source of ecological unrest in diverse ecosystems. The high toxicity level of cobalt in surface water has drawn a lot ofattention; hence,a low-cost adsorbent made from leaves and fibres of Camellia sinensis has been developed to remove cobalt from wastewater. The kinetics of the pseudo-first and second-order sorption interaction, as well as the physicochemical parameters of the precursor adsorbent, was investigated. There was a linear relationship between Cobalt uptake and biosorbent dosage under ideal conditions; the optimum dosage was 4 g. Between 10 to 40 minutes of contact time, clearance of cobalt was greater than 90 per cent. The Gibb’s free energy (∆Go) at various temperatures ranges from -9980 to -1020, indicating a spontaneous system, viable for both parts of the precursor adsorbent. The entropy change (∆So) was found to be +31.05 and +35.12 for tea leaves and fibre respectively, implying a highly disordered biosorption interface. The enthalpy (∆Ho) was found to be-8.58 and -10.03 for tea leaves and fibres hence, an exothermic system was suggested by the enthalpy with a second order kinetics. Therefore, Camellia sinensis is a suitable adsorbent for the effective removal of high cobalt concentrations in wastewater.

Eco-Friendly Remediation: Tea Leaves and Fibres as Adsorbents for High Cobalt Concentrations; Thermodynamics, Isotherms and Kinetic Studies

Increasing industrialization has produced huge amounts of liquid effluents, which are a key source of ecological unrest in diverse ecosystems. The high toxicity level of cobalt in surface water has drawn a lot ofattention; hence,a low-cost adsorbent made from leaves and fibres of Camellia sinensis has been developed to remove cobalt from wastewater. The kinetics of the pseudo-first and second-order sorption interaction, as well as the physicochemical parameters of the precursor adsorbent, was investigated. There was a linear relationship between Cobalt uptake and biosorbent dosage under ideal conditions; the optimum dosage was 4 g. Between 10 to 40 minutes of contact time, clearance of cobalt was greater than 90 per cent. The Gibb’s free energy (∆Go) at various temperatures ranges from -9980 to -1020, indicating a spontaneous system, viable for both parts of the precursor adsorbent. The entropy change (∆So) was found to be +31.05 and +35.12 for tea leaves and fibre respectively, implying a highly disordered biosorption interface. The enthalpy (∆Ho) was found to be-8.58 and -10.03 for tea leaves and fibres hence, an exothermic system was suggested by the enthalpy with a second order kinetics. Therefore, Camellia sinensis is a suitable adsorbent for the effective removal of high cobalt concentrations in wastewater.

Serpentine environment prevails over geographic distribution in shaping the genetic diversity of Medicago lupulina L.

Edaphic conditions of serpentine soils, naturally rich in heavy metals, act as a strong selection pressure that shapes specific metal-tolerant ecotypes. Medicago lupulina L. (black medick) is not only a widespread plant species that prefers calcareous and dry soil types but also grows at the borders of serpentine formations. It can also be found in waste and disturbed habitats. This is a species with reported phytoremediation potential, however, there is no published data regarding the impact of the environment on the genetic distribution of this species. The aim of our research was to explore how selection pressure of serpentine soils affects genetic diversity of M. lupulina and to test heavy-metal accumulation capacity of this species. Specimens of 11M. lupulina populations were collected from serpentine outcrops located in Central and Eastern Bosnia as well as from non-serpentine sites. Soil and plant samples were analyzed for the total contents of heavy metals using air-acetylene flame atomic absorption spectroscopy. Genetic diversity was analyzed using AFLP (Amplified Fragment Length Polymorphism) markers. Serpentine soils showed high nickel, cobalt, chromium and iron concentrations. Nickel and manganese concentrations in soil samples and plant material showed statistically significant correlation. Although plants in two populations show the ability to extract Ni, M. lupulina does not show hyperaccumulating properties. Despite severe selective pressure, genetic diversity in serpentine populations is not reduced. Analyses of intrapopulation and interpopulation genetic diversity showed significant genetic differentiation among populations which is not related to their geographic distance. Population from non-metalliferous soil showed clear separation from all other populations. Diversity data suggest that serpentine populations maintain genetic diversity by undetected mechanisms and that edaphic factors rather than geography influence genetic structure analyzed M. lupulina populations.

Cobalt's role in modulating antioxidant systems and semen quality in males.

The present study investigated associations between environmental exposure to cobalt (Co) and the levels of oxidative stress parameters and the antioxidant defense system in the seminal plasma of fertile males. The study population consisted of 117 healthy, non-smoking, fertile men from the southern region of Poland. The study was carried out in 2021–22. Based on the median cobalt levels in seminal plasma, subjects were divided into two groups: those with low (Co-L) and high (Co-H) cobalt concentrations. Semen parameters assessed according to WHO 2021 recommendations. After the analysis of spermiograms, observed reduction in progressive motility after 1hour was found in the Co-H group. Moreover, superoxide dismutase (SOD), glutathione S-transferase (GST) in the Co-H group had lower activity and GR higher activity. The OSI (Oxidative stress index) were higher in the group with high cobalt concentration in semen. The concentrations of redox balance parameters: TOS, TAC and OSI significantly were higher in the Co-high group as well as GR activity. Environmental exposure to cobalt decreases sperm motility in both normal and abnormal semen. The findings from this study affirm that cobalt can induce oxidative stress and alter oxidative stress markers in semen.

Ecotoxicology of Polymetallic Nodule Seabed Mining: The Effects of Cobalt and Nickel on Phytoplankton Growth and Pigment Concentration.

In order to improve the understanding of the environmental impacts of polymetallic nodule mining, ecotoxicological studies were conducted on the growth of model phytoplankton species Skeletonema costatum and Prorocentrum donghaiense using cobalt and nickel. This study evaluated various physiological and ecological indicators, such as cell proliferation, chlorophyll a, pigments, total protein, and antioxidant enzyme markers. The results show that the introduction of low amounts of cobalt or nickel increased the growth rate of phytoplankton. The phytoplankton benefited from low concentrations of cobalt and nickel stress. The increased protein levels and decreased activity of antioxidant enzymes considerably impacted physiological responses during the promotion of cell abundance. High concentrations of cobalt or nickel resulted in decreased light-absorbing pigments, increased photoprotective pigments, an inactive chlorophyll content, decreased total proteins, and maximal antioxidant enzyme activity in phytoplankton. Throughout the experiment, both the phytoplankton protein and enzyme activity declined with prolonged stress, and the cells underwent age-induced damage. Thus, seabed mining's repercussions on phytoplankton could result in both short-term growth promotion and long-term damage. These consequences depend on the impurity concentrations infiltrating the water, their duration, and the organism's physiological responses.

Enhanced DC electrical resistivity and magnetic properties of transition metal cobalt substituted spinel MgFe2O4 ferrite system

Cobalt-substituted magnesium ferrite materials, denoted as Mg1-xCoxFe2O4 (with × = 0.0, 0.25, 0.5, and 0.75), were synthesized using the solid-state reaction method at 1200 °C. This study aimed to investigate these ferrite systems' morphology, structure, DC electrical resistivity, and magnetic characteristics. Various analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier-transform infrared (FT-IR) spectroscopy, DC electrical resistivity measurements, and vibrating sample magnetometer (VSM), were employed to assess the phase purity, microstructure, elemental composition, functional groups, resistivity, activation energy, and magnetic properties of the ferrite particles. The XRD patterns revealed a spinel cubic structure with the Fd3m space group. SEM images exhibited a few agglomerations and grains with spherical and polyhedral shapes, measuring 1.5 to 2 µm. The FTIR spectrum displayed two wavebands (ν1 and ν2) in the range of 400 cm−1 to 600 cm−1, corresponding to the lattice's tetrahedral and octahedral sites. Activation energies, which increased with higher cobalt concentrations, were calculated from DC electrical resistivity measurements. Furthermore, saturation magnetization and coercivity values gradually increased with rising cobalt concentrations.

Evaluation of Structural, Magnetic, and Electromagnetic Properties of Co2+-Substituted NiCuZn Ferrites.

We report citrate gel-assisted autocombusted spinel-type Co2+-substituted NiCuZn ferrites and their electromagnetic properties. Several complementary techniques were used to investigate the influence of Co on structural and electromagnetic properties of Ni0.25-xCoxCu0.20Zn0.55Fe2O4 with x = 0.00-0.25 (step of 0.05). XRD analysis confirmed the highly crystalline single-phase cubic spinel structure with a prominent peak of the (311) plane. FE-SEM analysis showed the loss of porous gel structure (colloidal backbone) due to addition of cobalt into the present ferrite system. The EDAX analysis confirmed the presence of Ni, Cu, Zn, Co, and O in accordance with the relative stoichiometry of Co-substituted NiCuZn ferrite. The electrical resistivity of ferrites is observed to decrease when Co2+ ions are substituted, regardless of AC and DC. The dielectric properties (ε' and ε″) of ferrites exhibited a consistent decrease as the frequency increased, and this trend persisted even at higher frequencies. VSM analysis showed the normal magnetic hysteresis of the developed ferrite system. At x = 0.05, the saturation magnetization of the ferrite was obtained to be the highest among the other substitution levels of Co. The Curie temperature fell down when there was a higher concentration of cobalt in the ferrite system (x = 0.20). After reaching a specific temperature, the μi values decreased abruptly, with an increase in the temperature. The steady state may be deduced from the fact that the constant real component of the initial permeability, μ', remained unchanged. However, with decreasing frequency, the values of μ″ decreased dramatically. The present NiCuZn ferrite series displays the enhanced dielectric properties suggesting the capability of potential candidates for microwave absorption applications with enhanced electromagnetic properties.

Reflectance spectroscopy as a promising tool for ‘sensing’ metals in hyperaccumulator plants

Main conclusionThe VNIR reflectance spectra of nickel hyperaccumulator plant leaves have spectral variations due to high nickel concentrations and this property could potentially be used for discovery of these plants. Hyperaccumulator plants accumulate high concentrations of certain metals, including manganese, cobalt, or nickel. Of these metals, the divalent ions of nickel have three absorption bands in the visible to near-infrared region which may cause variations in the spectral reflectance of nickel hyperaccumulator plant leaves, but this has not been investigated previously. In this shortproof-of-concept study, the spectral reflectance of eight different nickel hyperaccumulator plant species leaves were subjected to visible and near-infrared and shortwave infrared (VNIR-SWIR) reflectance spectrum measurements in dehydrated state, and for one species, it was also assessed in hydrated state. Nickel concentrations in the plant leaves were determined with other methods and then correlated to the spectral reflectance data. Spectral variations centred at 1000 ± 150 nm were observed and had R-values varying from 0.46 to 0.96 with nickel concentrations. The extremely high nickel concentrations in nickel hyperaccumulator leaves reshape their spectral reflectance features, and the electronic transition of nickel-ions directly contributes to absorption at ~ 1000 nm. Given that spectral variations are correlated with nickel concentrations it make VNIR-SWIR reflectance spectrometry a potential promising technique for discovery of hyperaccumulator plants, not only in the laboratory or herbarium, but also in the field using drone-based platforms. This is a preliminary study which we hope will instigate further detailed research on this topic to validate the findings and to explore possible applications.

Alleviating the toxic effects of Cd and Co on the seed germination and seedling biochemistry of wheat (Triticum aestivum L.) using Azolla pinnata

One of the most significant environmental challenges in the twenty-first century is heavy metal pollution. The potential use of fresh Azolla pinnata to alleviate the toxic effects of Cd and Co on the germination measurements of wheat seeds (Triticum aestivum L.) and the biochemistry of seedlings was studied. Two concentrations (80 and 100 mg L−1 solutions) of CdNO3 and CoCl2 were used before and after treatment with A. pinnata. The highest removal efficiency (RE) by A. pinnata was obtained on the fifth day, with a Cd RE = 55.9 and 49.9% at 80 and 100 mg L−1, respectively. Cadmium and cobalt solutions reduced the germination percentage, and the measured variables of wheat seeds meanwhile increased the radicle phytotoxicity. In contrast, the presence of A. pinnata in the germination medium increased all the measured variables and decreased radicle phytotoxicity. At 80 and 100 mg L−1, Cd significantly reduced the fresh and dry biomass, and height of wheat seedlings after 21 days of cultivation compared to Co. Cadmium and high concentrations of cobalt increased the contents of H2O2, proline, MDA, phenolic, and flavonoid compounds. The application of treated Cd and Co solutions by A. pinnata showed a decrease in H2O2, proline, phenolic, and flavonoid compounds levels accompanied by a reduction in catalase and peroxidase activities compared to the control. This study showed the positive role of A. pinnata in alleviating the metal impacts, particularly Cd, on the seedling growth of wheat and its germination.

Zinc enrichment and isotopic fractionation in a marine habitat of the c. 2.1 Ga Francevillian Group: A signature of zinc utilization by eukaryotes?

Constraining the timing of eukaryogenesis and the divergence of eukaryotic clades is a major challenge in evolutionary biology. Here, we present trace metal concentration and zinc isotope data for c. 2.1 billion-year-old Francevillian Group pyritized structures, previously described as putative remnants of the first colonial multicellular organisms, and their host black shales. Relative to the host rocks, pyritized structures are strongly enriched in zinc, cobalt and nickel, by at least one order of magnitude, with markedly lighter zinc isotope compositions. A metabolic demand for high concentrations of aqueous zinc, cobalt, and nickel combined with preferential uptake of lighter zinc isotopes may indicate metalloenzyme utilization by eukaryotes in marine habitats c. 2.1 billion years ago. Once confirmed, this would provide a critical calibration point for eukaryogenesis, suggesting that this major evolutionary innovation may have happened contemporaneously with elevated atmospheric oxygen levels during the latter part of the Great Oxidation Event, some 400 million years earlier than is currently widely accepted.

Cobalt-Doped Chalcopyrites CuGaSe2: Synthesis and Magnetic Properties

Two series of cobalt-doped CuGa1 – xCoxSe2 and Cu1 – x/2Ga1 – x/2CoxSe2 chalcopyrites were prepared. Cobalt in part entered the chalcopyrite structure to ensure the appearance of paramagnetic properties, while in part it remained involved in cobalt selenide admixtures. High-temperature quenching forced almost all of the cobalt to enter the crystal structure in the Cu1 – x/2Ga1 – x/2CoxSe2 samples. Significant ferromagnetism appears in the Cu0.9Ga0.9Co0.2Se2 sample, which had the highest cobalt concentration, in particular at room temperature.

Effect of metals on the regulation of acidogenic metabolism enhancing biohydrogen and carboxylic acids production from brewery spent grains: Microbial dynamics and biochemical analysis.

The present study reports the mixed culture acidogenic production of biohydrogen and carboxylic acids (CA) from brewery spent grains (BSG) in the presence of high concentrations of cobalt, iron, nickel, and zinc. The metals enhanced biohydrogen output by 2.39 times along with CA biosynthesis by 1.73 times. Cobalt and iron promoted the acetate and butyrate pathways, leading to the accumulation of 5.14 gCOD/L of acetic and 11.36 gCOD/L of butyric acid. The production of solvents (ethanol + butanol) was higher with zinc (4.68 gCOD/L) and cobalt (4.45 gCOD/L). A combination of all four metals further enhanced CA accumulation to 42.98 gCOD/L, thus surpassing the benefits accrued from supplementation with individual metals. Additionally, 0.36 and 0.31 mol green ammonium were obtained from protein‐rich brewery spent grain upon supplementation with iron and cobalt, respectively. Metagenomic analysis revealed the high relative abundance of Firmicutes (>90%), of which 85.02% were Clostridium, in mixed metal‐containing reactors. Finally, a significant correlation of dehydrogenase activity with CA and biohydrogen evolution was observed upon metal addition.

Willow leaves as a cobalt supplement for weaned lambs

Cobalt is an essential trace element in sheep for the synthesis of vitamin B12 in the rumen to support growth and prevent clinical deficiencies (Pine). Willow (Salix spp.) leaves contain a high concentration of cobalt (∼6 times the requirement of lambs). The aim of this study was to determine the efficacy of supplementary willow leaves in improving plasma vitamin B12 status of sheep. Weaned lambs (n=24) on ad libitum grass were randomly allocated to one of three groups: Willow (offered up to 300 g of fresh willow leaves per lamb each day); Drench (2.8mg oral cobalt sulphate heptahydrate drench on day 0); Control (received no treatment). Plasma B12 concentration was evaluated for all lambs using blood samples taken on days 0 and 14. Values for plasma B12 concentration were log transformed prior to statistical analysis. At day 14 the mean (± s.d.) concentrations, on the log10 scale, were 3.00 (±0.155) pmol/L, 2.61 (±0.146) pmol/L and 2.55 (±0.214) pmol/L for Willow, Drench and Control, respectively. The corresponding back transformed means were 990 pmol/L, 407 pmol/L, 351 pmol/L, respectively. The value for the Willow treatment was significantly higher than each of the other treatments, which did not differ significantly. Supplementary willow can be used by producers to improve vitamin B12 status in lambs.

Recovery of rare earth elements from spent NiMH batteries using subcritical water extraction with citric acid

Spent nickel-metal hydride (NiMH) batteries contain high concentrations of rare earth elements (REEs), nickel (Ni), and cobalt (Co). Subcritical water extraction (SWE) process with citric acid as the leaching reagent was applied to spent NiMH batteries. The effects of acid concentration, solid to liquid ratio (S/L), reaction time, and reaction temperature were examined. Leaching efficiency increased with increasing acid concentration, reaction time and temperature, and decreased as S/L increased. Total of 90.85% of lanthanum (La), 88.84% of cerium (Ce), 90.85% of neodymium (Nd), 90.70% of Ni, and 91.62% of Co were leached out using 2.0 N of citric acid, S/L of 10 g/L, at 150 °C in 5 min. Selective precipitation of REEs was induced by the addition of diluted waste phosphoric acid (H3PO4) to the leaching solutions. At [H3PO4]:[REEs] of 10:1, pH 2.0, and 65 °C, 99.3% of La, 98.8% of Ce, and 99.0% of Nd were precipitated, which correspond to overall recovery of 90.2% of La, 87.8% of Ce, and 89.8% of Nd. The results showed that SWE using citric acid followed by selective precipitation with H3PO4 could effectively recover REEs from spent NiMH batteries.

Binary CoOx–SiO2 Porous Nanostructures for Catalytic CO Oxidation

Via integrative chemistry, the first CoOx–SiO2(HIPE) self-standing monoliths of cobalt nano-oxides embedded within silica macro–mesocellular hosts have been prepared. These binary CoOx–SiO2 porous nanostructure (MUB-100(x)) materials present an average of 95% porosity. We found out that high cobalt concentration maintains the hexagonal-2D organization of the mesoscopic voids when applying the thermal treatment at 700 °C. Their specific surface areas fall between 400 and 500 m2 g–1 when assessed by Ar physisorption measurements. At the microscopic length scale, as revealed through magnetic investigations, the low cobalt content foams MUB-100(1) and MUB-100(2) are made of the amorphous β-Co(OH)2 phase coexisting with the silica network, whereas increasing the cobalt concentration during the one-pot syntheses (MUB-100(3) and MUB-(4) materials) favors the formation of the spinel Co3O4 and olivine Co2SiO4 crystalline nanoparticles embedded within silica. When considering the CO oxidation catalytic performance, the MUB-100(4) is able to totally convert the CO flow before 200 °C (starting at 125 °C) while achieving 50% conversion for a light-off temperature (T50) of 145 °C, revealing the good efficiency of the MUB-100(4) in CO oxidation with which up to 4 catalytic cycles have been performed without disrupting drastically the catalytic performance and reaching thermodynamic stability from cycle 2 to cycle 4.

Optical and magnetic properties of cobalt doped TiN thin films grown by RF/DC magnetron sputtering

Here we report the study of cobalt doped titanium nitride thin films grown by reactive co-sputtering of cobalt and titanium targets in the presence of argon and nitrogen gases. Thin films were grown with different cobalt concentrations and analyzed by atomic force microscopy, spectrophotometry, X-ray photoelectron spectroscopy, X-ray reflectometry and vibrating sample magnetometry. We have found that the films readily oxidize after exposure to the atmosphere and form a cobalt doped titanium oxynitride. The variable cobalt concentration in the films affects the optical, chemical and magnetic properties. The bandgap of the films generally becomes narrower at higher cobalt concentrations. Cobalt is found to be in a mixture of the high spin + 2 and low spin + 3 oxidation states. At the lower cobalt concentrations, the magnetization is low and it is temperature-independent. Whereas at higher cobalt concentrations, the magnetic response becomes temperature-dependent with a mix of paramagnetism and superparamagnetism at 3–5 K.

IMPACT OF AIR POLLUTION ON LEVEL OF ESSENTIAL MINERAL CONTENT AND HEAVY METAL OF PLANT SPECIES FROM CHEMBUR INDUSTRIAL AREA OF MUMBAI, INDIA

The rapid development in urban and industrial areas has risen the air pollution problem for a few decades. Plants leaves can maintain their essential mineral content even under the air pollution stress and can survive for a longer period. Aiming at the current issue of air pollution, the present study was carried out to determine heavy metal and essential element concentration present in twelve landscape plant species collected from the Chembur industrial area of Mumbai. Heavy metal accumulation in leaves exhibits an impact on plant metabolic processes. The highest cobalt concentration (3.07 ppm) was reported by Prosopis juliflora (Sw.) DC. in the rainy season. The highest chromium concentration was reported by Calotropis gigantea (L.) Dryand (11.38 ppm) in the summer season. Calcium mineral content was found to be maximum for Leucaena leucocephala (Lam.) de wit (60472 ppm) in the summer season. The highest potassium mineral content was observed for Polyalthia longifolia (27738 ppm) in the rainy season. Apluda mutica L. has reported the highest magnesium content (8475 ppm) in the summer season and Calotropis gigantea (L.) Dryand has reported the highest sodium content (10028 ppm) in the summer season. Raised heavy metal load of plant leaves reduces the essential mineral content of plant species. Leucaena leucocephala (Lam.) de wit, Polyalthia longifolia, Apluda mutica L., Calotropis gigantea (L.) Dryand could maintain the mineral content necessary for metabolic processes and can survive for a longer duration even under pollution stress. Also, these plant species exhibited cobalt and chromium concentration in normal limits as well as have certain medicinal values. Hence these plant species can be planted in large numbers around the industrial area to develop green zone and for their medicinal uses.