Mixture Of Cd Research Articles

Alleviative effects of dietary Indian lotus leaves on heavy metals-induced hepato-renal toxicity, oxidative stress, and histopathological alterations in Nile tilapia, Oreochromis niloticus (L.)

Heavy metals (HM) are widespread contaminants of water affecting aquatic organisms and aquatic ecosystems. Indian lotus, Nelumbo nucifera (Gaertn.), is a beneficial medicinal plant that exhibits several pharmacological properties. It is hypothesized that incorporation of Indian lotus leaf (ILL) powder may be able to alleviate toxic effects exerted by a mixture of lead (Pb), cadmium (Cd), mercury (Hg), and zinc (Zn) in Nile tilapia, Oreochromis niloticus (L.). A total of two hundred and forty fish were randomly allocated into eight groups in triplicate, in a bifactorial design (4 ILL levels × 2 HM exposures). The fish in the first four groups were fed on a basal diet (39.9% crude protein) that was enriched with 0.0, 0.1, 0.2, and 0.4% ILL (in G1–G4, respectively), with no HM exposure. In the remaining four groups, fish were fed with the same diets and, in addition, were exposed to 1/20 of the 96 h-LC50 of Pb, Cd, Hg, and Zn mixture (in G5–G8, respectively), for 45 days. The HM exposure significantly elevated the levels of serum alanine and aspartate aminotransferases, creatinine, urea, malondialdehyde, and activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX). The expression level of hepatic metallothionein (MT) was up-regulated as well as high residual levels of HM in fish musculature were recorded in the HM-exposed fish. Two-way ANOVA revealed that all the studied variables were significantly affected by the ILL supplementation, HM exposure, and their interaction. Moreover, levels of MDA, CAT, SOD, and MT showed significant positive correlations with HM concentrations. Moreover, necrosis and degeneration of hepatopancreatic cells with congestion, hyperplasia, and fusion of gills lamellae were observed in HM-exposed fish. Interestingly, ILL supplementation, especially in the fish fed with 0.2 and 0.4% ILL, was observed to reduce the HM concentration in the fish body, resulting in the reduction of its toxic effects on the biochemical and antioxidant activities. These results demonstrated that dietary ILL supplementation could protect Nile tilapia against the toxic effects of HM, and therefore, may serve as a beneficial feed additive for application in the aquaculture industry.

Application of Stabilized Nano Zero Valent Iron Particles for Immobilization of Available Cd2+, Cu2+, Ni2+, and Pb2+ Ions in Soil

The present manuscript studies the effectiveness of commercial nano zero valent iron (nZVI) particles in decreasing the availability of Cd, Cu, Ni, and Pb in spiked soil samples and to remove the same heavy metals from aqueous solutions. The difference of nZVI efficiency between single and multi-metal contamination was evaluated. The application of nZVI in water samples showed higher effectiveness in the cases of single metal contamination. The effectiveness of single- and multi-metal (mixtures of Cu, Ni, Pb and Cd, Cu, Ni, Pb) immobilization in soil using different doses (0%, 0.85%, 1.7%, 2.55%, and 5.1%) of nZVI was determined. Immobilization efficiency was assessed using the leaching procedure and depended on a particular metal and the dose of nZVI. In all cases, it was determined that an increasing amount of nZVI resulted in decrease in the leaching of analysed metals. In cases, where higher nZVI doses were used, higher immobilization efficiency was observed for heavy metals in multi-metal contamination. The application of nZVI significantly reduced leaching of all heavy metals and this strategy can be successfully used for heavy metals stabilization in soils.

Selenium restricts cadmium uptake and improve micronutrients and proline concentration in tomato fruits

Abstract In order to identify the beneficial effects of Selenium (Se) in tomato (Solanum lycopersicum), genotypes MT and hp1, under Cadmium (Cd) toxicity, the following analyses were performed: Cd and Se concentration and translocation index in roots, leaves and fruits as well as the macro and micronutrients quantification, proline concentration, fruits dry weight, chlorophyll and carotenoids concentration in fruits. Se reduced the Cd concentration in roots of both genotypes. The Cd translocation to above ground parts were restricted by Se only in the MT genotype. Fruit proline concentration increased either in genotype hp1 when Se was applied alone or in the MT genotype, by the mixture of Se and Cd. When Se was applied alone the concentration of Mn and Zn in hp1 fruits and Fe in MT fruits were enhanced. The beneficial mechanisms of Se to tomato plants under Cd stress could be partially related to the restriction of Cd uptake and translocation, enhancing proline concentration and micronutrient improvements in fruits.

Evaluation of the properties of the essential oil citronellal nanoencapsulated by cyclodextrins.

In this work we used natural and modified cyclodextrins (β-CD and HP-β-CD) as encapsulating agents to improve citronellal properties. Using fluorimetric techniques, its aggregation behavior was studied for the first time. Its critical micellar concentration was seen to vary with the presence of cyclodextrins, which form 1:1 stoichiometry complexes with citronellal. The encapsulation constants and the scores obtained by Molecular Docking were correlated. Chromatographic (GC-MS) and sensory analysis confirmed that cyclodextrins improve the persistence of the aroma. Finally, the antimicrobial effect of citronellal against Escherichia coli and Bacillus subtilis in the presence and absence of cyclodextrins was studied. A combinatorial effect of citronellal, HP-β-cyclodextrin and Glucobay® as an antimicrobial mixture was observed. The results of this study not only demonstrated the potential of CD mixtures, but also that the growth caused by CD digestion may sometimes be greater that the antimicrobial effect of the agents used in this study.

Interactions of Cd, Cr, Pb, Ni, and Hg in their effects on activated sludge bacteria by using two analytical methods

Since trace metals rarely appear singly in industrial effluents, it is a major challenge to address combined effects of such toxicants on biological units of wastewater treatment plants. The aim of this study was interaction assessment of Cd, Cr, Pb, Ni, and Hg in their effects on activated sludge bacteria using analytical methods. Two mathematical models were used to determine the effect of binary mixtures of Hg, Cd, Cr, Pb, and Ni on activated sludge bacteria using a dehydrogenase enzyme assay. Calculated EC50 values were compared to experimentally observed values of mixtures. Interactive effects were counted to be antagonistic for Hg and Cd, Cd and Pb, Cd and Ni, and Cr and Pb, synergistic for Cd and Cr and Hg and Cr, and additive for other binary mixtures. Maximum toxicity was related to Hg and Cr, Cd and Cr, and Hg and Cd. Physicochemical monitoring of single metals may underestimate hazards arising from these pollutants in environmental samples. Therefore, any possible interaction between metals in such environments should be considered when establishing environmental safety standards.

Effect of Solvent on the Structural Diversity of Quasi-Aromatic Möbius Cadmium(II) Complexes Fabricated from the Bulky N6 Tetradentate Helical Ligand

We present the synthesis and structural and computational characterization of a heteroleptic dinuclear discrete complex [Cd2(μ1,3-NCS)2(NCS)2(LI)2]·4MeOH (1·4MeOH), where LI is the product of hydrolysis of one of the 2-PyC(Ph) groups of the parent ligand 1,2-diphenyl-1,2-bis((phenyl(pyridin-2-yl)methylene)hydrazono)ethane (L), fabricated from a mixture of Cd(NO3)2·4H2O and NH4NCS in methanol. An analogous procedure but in EtOH and iPrOH yielded crystals of the heteroleptic dinuclear discrete complex [Cd2(μ1,3-NCS)2(NCS)2(L)2] (2) and the polymeric complex of the composition [Cd3(NCS)6(L)]n (3). The bulky helical ligand L in the constituting CdII based synthons has been found to exhibit a quasi-aromatic Mobius features as revealed by the electron density of delocalized bonds method as well as the extended transition state coupled with natural orbitals for chemical valence calculations. It means that a transition metal induces π-electron delocalization solely in the ligand’s part; however, the d orbitals of...

Effects of β-cyclodextrin on phytoremediation of soil co-contaminated with Cd and BDE-209 by arbuscular mycorrhizal amaranth

Pot experiments were conducted to investigate the effects of a series of β-cyclodextrin (β-CD) on phytoremediation of soil co-contaminated with Cd and BDE-209 by amaranth (Amaranthus hypochondriacus L.) inoculated with arbuscular mycorrhizal fungus (AMF) – Rhizophagus intraradices. Results showed that the combination of mycorrhizal amaranth and 0.4% β-CD (RI+β0.4) significantly enhanced Cd concentrations and contents in shoots, total PBDEs concentration in roots, and BDE-209 dissipation in soil. Moreover, the RI+β0.4 treatment exerted the highest removal efficiency of both Cd and BDE-209. On the contrary, the xylem area, shoot Cd and BDE-209 concentrations and contents, and removal efficiency of Cd were markedly reduced in mycorrhizal amaranth with 0.8% or 1.2% β-CD treatments (RI+β0.8, RI+β1.2), compared with single inoculation treatment. The well-organized chloroplast and well-defined root anatomical structure were also observed in the treatment of RI+β0.4. Positive correlation was found between shoot biomass and chlorophyll concentrations. Shoot Cd or BDE-209 concentrations were positively correlated with xylem areas. In conclusion, mycorrhizal amaranth added with 0.4% β-CD could be used for the decontamination of soil polluted with mixture of Cd and BDE-209 due to the higher chlorophyll concentration and the larger xylem area.

Toxic Effect of Acute Cadmium and Lead Exposure in Rat Blood, Liver, and Kidney.

Background: Cadmium and lead are widespread and non-biodegradable pollutants of great concern to human health. In real life scenarios, we are exposed to mixtures of chemicals rather than single chemicals, and it is therefore of paramount importance to assess their toxicity. In this study, we investigated the toxicity of Cd and Pb alone and as a mixture in an animal model of acute exposure. Methods: Experimental groups received a single treatment of aqueous solution of Cd-chloride (15 and 30 mg/kg body weight (b.w.) and Pb-acetate (150 mg/kg b.w.), while the mixture group received 15 mg Cd/kg b.w. and 150 mg Pb/kg b.w. Toxic effects of individual metals and their mixture were investigated on hematological and biochemical parameters, and the redox status in the plasma, liver, and kidneys of treated Wistar rats. Results: Tissue-specific changes were recorded in various parameters of oxidative damage, while the accumulation of metals in tissues accompanied the disturbances of both hematological and biochemical parameters. It was observed that the level of toxic metals in tissues had a different distribution pattern after mixture and single exposure. Conclusions: Comprehensive observations suggest that exposure to Cd and Pb mixtures produces more pronounced effects compared to the response observed after exposure to single metal solutions. However, further research is needed to confirm toxicokinetic or toxicodynamic interactions between these two toxic metals in the organisms.

The essentialness of glutathione reductase GorA for biosynthesis of Se(0)-nanoparticles and GSH for CdSe quantum dot formation in Pseudomonas stutzeri TS44.

Pseudomonas stutzeri TS44 was able to aerobically reduce Se(IV) into SeNPs and transform Se(IV)/Cd(II) mixture into CdSe-QDs. The SeNPs and CdSe-QDs were systematically characterized by surface feature analyses, and the molecular mechanisms of SeNPs and CdSe-QD formation in P. stutzeri TS44 were characterized in detail. In vivo, under 2.5 mmol/L Se(IV) exposure, GorA was essential for catalyzing of Se(IV) reduction rate decreased by 67% when the glutathione reductase gene gorA was disrupted, but it was not decreased in the glutathione synthesis rate-limiting gene gshA mutated strain compared to the wild type. The complemented strains restored the phenotypes. While under low amount of Se(IV) (0.5 mmol/L), GSH played an important role for Se(IV) reduction. In vitro, GorA catalyzed Se(IV) reduction with NADPH as the electron donor (Vmax of 3.947 ± 0.1061 μmol/min/mg protein under pH 7.0 and 28℃). In addition, CdSe-QDs were successfully synthesized by a one-step method in which Se(IV) and Cd(II) were added to bacterial culture simultaneously. GSH rather than GorA is necessary for CdSe-QD formation in vivo and in vitro. In conclusion, the results provide new findings showing that GorA functions as a selenite reductase under high amount Se(IV) and GSH is essential for bacterial CdSe-QD synthesis.

Triggered Reversible Reconfiguration of G-Quadruplex-Bridged "Domino"-Type Origami Dimers: Application of the Systems for Programmed Catalysis.

The reversible and switchable reconfiguration of the two-origami-dimer mixture AB plus CD into the dimer mixture DA plus BC and back using the triggered formation of K+-ion-stabilized G-quadruplexes and subsequent treatment with 18-crown-6-ether is presented. The reconfiguration processes are followed by atomic force microscopy imaging of the dimer structures that include tiles marked with 0, 1, 2, and 3 4× hairpin labels. By the functionalization of AB and CD dimers with the Mg2+-ion-dependent DNAzyme subunits, the AB plus CD mixture leads to the cleavage of the fluorophore- and quencher-modified substrate of the DNAzyme and to the activation of the fluorescence of the fluorophore (fluorescein)-modified fragment product. The K+-ion-induced isomerization of the mixture of AB plus CD into the mixture DA plus BC separates the Mg2+-ion-dependent DNAzyme subunits and concomitantly reconfigures the K+-ion-stabilized G-quadruplex associated with the two dimers. After the binding of hemin to the G-quadruplexes, the hemin/G-quadruplex DNAzyme is generated, leading to the catalyzed oxidation of AmplexRed by H2O2 to yield the fluorescent resorufin product. By the cyclic treatment of the AB plus CD mixture with K+ ions to yield the DA plus BC mixture and the subsequent recovery of the AB plus CD mixture by subjecting the DA plus BC mixture to 18-crown-6-ether, the fluorescence output signals of the system are switched on and off between the fluorescence of fluorescein and resorufin, respectively.

The impact of temperature on metal mixture stress: Sublethal effects on the freshwater isopod Asellus aquaticus

Chemical and natural factors have been demonstrated to interact and potentially change the toxicity of the individual stressors. Yet, while there exists a multitude of papers studying the temperature-dependent toxicity of single chemicals, little research exists on the impact of temperature on chemical mixtures. This paper investigates the effect of temperature on environmentally-relevant mixtures of Cd, Cu and Pb. We linked the effects on respiration, growth, feeding rate and activity of Asellus aquaticus to the free ion activities, as a measure for the bioavailability of the metals, and the body concentrations. We observed interactions of temperature and metal body concentrations on all sublethal endpoints, except activity. Mixture effects on accumulation and feeding rate were observed as well and even an interaction between metal body burden, mixture and temperature treatment was revealed for the feeding rate of Pb exposed isopods. This research adds to a growing body of evidence that the current chemical-based monitoring is insufficient to estimate chemical toxicity in aquatic ecosystems and must, therefore, be complemented with effect-based tools.

Cellular alterations in midgut cells of honey bee workers (Apis millefera L.) exposed to sublethal concentrations of CdO or PbO nanoparticles or their binary mixture

Beside many beneficial applications in industry, agriculture and medicine, nanoparticles (NPs) released into the environment might cause adverse effects. In the present study, effects of exposure to sublethal concentrations of PbO and CdO NPs, either separately or in combination on honey bee (A. mellifera) workers were assessed. Honey bee workers were fed sugar syrup contained (20% of LC50) of CdO (0.01 mg ml−1) and PbO (0.65 mg ml−1) NPs either separately or combined for nine days under laboratory conditions. Control bees were fed 1.5 M sucrose syrup without NPs. Effects on histological and cellular structure of mid gut cells were investigated using light and electron microscope. Percentages of incidence of apoptosis or/and necrosis in mid gut cells were also quantified by use of flow cytometry. Rapture of the peritrophic membrane (PM) was among the most observed histopathological alteration in bees fed sugar syrup contained CdO NPs separately or combined with PbO NPs. Common cytological alterations observed in epithelial cells were irregular distribution or/and condensation of nuclear chromatin, mitochondrial swelling and lysis, and rough endoplasmic reticulum (rER) dilation, fragmentation, and vesiculation and were quite similar in all treated groups compared to control. The greatest incidence (%) of necrosis was observed in bees fed the diet that contained CdO NPs alone. The greatest % of both apoptosis and necrosis was observed in bees fed sugar syrup spiked with sublethal concentrations of both metal oxide NPs. Joint action of the binary mixture of Cd and Pb oxide NPs on honey bees was concluded to be antagonistic. Collectively, exposure of honey bees to these metal oxide NPs even at sublethal concentrations will adversely affect viability of the colony and further studies are still required to determine the effects of these metal oxide NPs on behavior and pollination ecology of honeybees.

Copper recovery from model chloride solution using polymer inclusion membranes with 1-decyl-2,4-dimethylimidazle

The recovery of Cu(II) ions from chloride solutions by the transport of a binary Cu(II)-Zn(II) and Cu(II)-Cd(II), and a ternary Cu(II)-Zn(II)-Cd(II) mixture ions through inclusion membranes doped with 1-decyl-2,4-dimethylimidazole (DDMI) was studied (cM(II) = 0.001 M; pH 5.5). The efficiency of metal ions separation by DDMI increased as: Cu(II) > Zn(II) > Cd(II). Selectivity coefficients Cu(II)/Zn(II) and Cu(II)/Cd(II) were equal 1.5 and 13.5, respectively for binary solutions and 1.6 and 27.7 for ternary solution. The step limiting the rate of transport of metal ions by PIM doped with DDMI may be membrane diffusion coefficients of cation complexes with DDMI. The recovery factor of Cu(II), Zn(II), and Cd(II) ions during transport across PIMs from an equimolar mixture of cations after 24 hrs was above 96%, 60% and 3.5% for Cu(II), Zn(II) and Cd(II), respectively. PIM containing DDMI are stable for 120 hrs.

Multi-component mathematical model based on mass transfer coefficients for prediction of the Zn and Cd ions biosorption data by E. densa in a continuous system

The objective of this study was to evaluate the biosorption dynamics of heavy metals by the dead macrophyte Egeria densa in fixed bed column. Experiments were conducted with mono- and bi-component solutions of Cd(II) and Zn(II) at pH 4.0, temperature of 30 °C and volumetric flow rate range between 2 and 6 cm3 min−1. A mass transfer mathematical model was applied for describing the mono-component biosorption dynamics. In this model, the equilibrium was represented by the batch Langmuir isotherm, and intraparticle diffusion was considered as the rate-limiting step for the mass transfer. The mass transfer coefficient (KS) was estimated by the downhill simplex optimization method for each volumetric flow tested, while the axial dispersion coefficient was calculated by empirical correlations. The KS coefficients and the equilibrium parameters obtained in a mono-component batch system were validated using data from the breakthrough curves of the Cd(II) and Zn(II) binary mixture obtained for different volumetric flows and initial concentrations of each metal ion.

Comparative effects of cadmium, zinc, arsenic and chromium on olfactory-mediated neurobehavior and gene expression in larval zebrafish (Danio rerio)

Studies have shown that olfactory-mediated behaviors that are critical to survival can be disrupted by exposure to certain metals. Polluted waterways often contain elevated levels of metals, yet only a subset have been characterized for their potential to cause olfactory toxicity. A larval zebrafish behavioral assay was developed to characterize concentration-response curves for zinc (Zn), hexavalent chromium (Cr), and arsenate (As) olfaction inhibition. Cadmium (Cd), an established olfactory toxicant, was used as a positive control. As expected, following a 24-hour exposure to Cd, we observed a reduced response to taurocholic acid (TCA), a substrate for ciliated olfactory sensory neurons (OSNs), thus validating the behavioral assay. Zn exposure similarly decreased the olfactory response toward TCA, (IC50: 36 μg/L and 76 μg/L, for Cd and Zn, respectively). The response towards a secondary odorant L-cysteine (Cys), a substrate for ciliated and microvillous OSNs, was significantly altered by both Cd and Zn exposure, although the response to Cys was not completely removed in Zn treated larvae, suggesting preferential toxicity towards ciliated OSNs. No significant changes in olfactory responses were observed following Cr and As exposures. Exposures to binary mixtures of Cd and Zn indicated that Zn had a protective effect against Cd toxicity at low Zn concentrations. QuantiGene (QDP) RNA analysis revealed Cd to be a potent inducer of metallothionein 2 (mt2) mRNA in zebrafish larvae, and Zn to be a weak mt2 inducer, suggesting a protective role of mt2 in Cd and Zn olfactory injury. By contrast, QDP analysis of eight other genes important in mitigating the effects of oxidative stress suggested an antioxidant response to Cd, but not Zn, As, and Cr suggesting that oxidative stress was not a primary mechanism of Zn-induced olfactory dysfunction. In summary, our study indicates that Zn inhibits zebrafish olfaction at environmental concentrations and may potentially mitigate Cd induced olfactory dysfunction when present in mixtures. The zebrafish behavioral trough assay incorporating the odorants L-cysteine and TCA is an effective assay to assess the effects of metals on olfactory function.

Effects of cadmium and copper mixtures to carrot and pakchoi under greenhouse cultivation condition

A pot experiment was undertaken to investigate the effects of Cd and Cu mixtures to growth and nutrients (sugar, carotene or vitamin C) of carrot and pakchoi under greenhouse cultivation condition. The study included: (a) physical-chemical properties of soil and soil animals in response to Cd and Cu stress; (b) bioaccumulation of heavy metals, length, biomass, contents of sugar and carotene (vitamin C) of carrot and pakchoi; (c) estimation the effects of Cd and Cu mixtures by multivariate regression analysis. The results implied that heavy metals impacted negative influence on soil animals’ abundance. The metals contents in plants increased obviously with Cd and Cu contamination in soil. The biomass production and nutrients declined with Cd and Cu contents increasing. Cd (20 mg kg−1) treatment caused maximum reduction of sugar content (45.29%) in carrot root; maximum reduction in carotene content (75.73%) in carrot, 75.1% sugar content reduction and 70.58% vitamin C content reduction in pakchoi shoots were observed with addition of Cd (20 mg kg−1) and Cu (400 mg kg−1) mixture. The results of multivariate regression analysis indicated that combination of Cd and Cu exerts negative effects to both carrot and pakchoi, and both growth and nutrients were negatively correlated with metals concentrations. It is concluded that the Cd and Cu mixtures caused toxic damage to vegetable plants as Cd and Cu gradient concentrations increased.

Growth and characterization of Cd1-xZnxTe (0 \leq x \leq 1) nanolayers grown by isothermal closed space atomic layer deposition on GaSb and GaAs

In this work are presented the results obtained from the deposition of Cd1-xZnxTe nanolayers using as precursor the vapours of the elements Zn, Te, and a mixture of Cd and Zn on GaAs and GaSb (001) substrates by Atomic Layer Deposition technique (ALD), which allows the deposition of layers of nanometric dimensions. At each exposure of the growth surface to the of cation or anion precursors vapours, this surface is saturated. Therefore, it is considered that the process is self-regulated. The ZnTe layers were grown in a wide range of temperatures; however, ZnTe nanolayers with a shiny mirror-like surface could be grown at temperatures between 370 and 410oC. Temperatures higher than 400oC were necessary for the CdTe growth. The layers of the Cd1-xZnxTe ternary alloy were deposited at temperature range of 400 and 425oC. The grown nanofilms were characterized by Raman spectroscopy and high-resolution X-ray diffraction. The Raman spectrum shows the peak corresponding to LO-ZnTe at 208 cm-1, which is weak and is slightly redshifted in comparison with the reported for the bulk ZnTe. For the case of the CdTe nanolayers, Raman spectrum presents the LO-CdTe peak, which is indicative of the successfully growth of the nanolayers, its weakness and its slight redshifted in comparison with the reported for the bulk CdTe can be related with the nanometric characteristic of this layer. The performed high resolution X-ray diffraction measurements allowed to study some important characteristics, as the crystallinity of the grown layers. Additionally, the performed HR-XRD measurements suggest that the crystalline quality have dependence with the growth temperature.

Combined effects of metal mixtures and predator stress on the freshwater isopod Asellus aquaticus

Biotic stressors have been demonstrated to change the toxicity of pollutants. While the combined effects of predator cues and pesticides are well documented, the interaction of predator stress with metals is a topic that has remained largely unexplored. In this laboratory experiment, the freshwater isopod Asellus aquaticus is exposed to predator cues and metal mixtures of Cd, Cu and Pb. We examined the effects on growth, respiration and, as behavioral parameters, feeding rate and activity. These were linked to the free ion activities (FIAs) in the water and the metal body concentrations. The findings reveal that Cu accumulation significantly influenced the growth rate, the feeding rate and the activity of isopods exposed to predator stress. Furthermore, we found a concentration-dependent interaction of the Cd + Pb mixtures on the feeding rate and a lower feeding rate for Cd and Pb predator exposed asellids. As several interactions were found between metals and predator stress, it demonstrates the importance of investigating how organisms and whole ecosystems respond to multiple stressors. A better understanding of these interactions will undoubtedly improve risk assessment and management.

Valorization of Adenanthera pavonina seeds as a potential biosorbent for lead and cadmium removal from single and binary contaminated system

This study investigated the biosorption of Pb (II) and Cd (II) on powdered seeds of Adenanthera pavonina from single and binary heavy metal solutions. The adsorption capacity of the metal ions was studied as a function of pH, adsorbent dose, initial metal ion concentration, and contact time. In the single heavy metal system, maximum removal of Pb (II) and Cd (II) were achieved at pH 4 and 6, respectively, while the equilibrium was attained at a contact duration of 35 min at a constant dose of 5 g L−1 was maintained for both Pb (II) and Cd (II). Further, the kinetic study revealed that the biosorption process was best described by the second-order kinetic model. In the competitive biosorption of binary mixtures of Pb (II) and Cd (II) were studied in terms of percentage removal of metal ions, adsorption capacity and equilibrium sorption isotherm. The percentage removal of metal ions in binary solutions was suppressed in presence of the other competitive metal ion. Field emission scanning electron microscopy integrated with energy dispersive X-ray spectroscopy of the biomass before (control) and after (metal loaded biomass) the biosoption process, confirmed the presence of respective heavy metal on to the biomass. Fourier transmission infrared spectroscopy spectra supported the activity of hydroxyl, amines, amides, and carboxyl groups in uptake of both heavy metal ions.

Switchable Triggered Interconversion and Reconfiguration of DNA Origami Dimers and Their Use for Programmed Catalysis.

The switchable reconfiguration of a mixture of two dimers of DNA origami tiles, AB and CD, into a mixture of two DNA origami dimers composed of AD and CB, using a collection of fuel and antifuel strands, is presented. The reversible reconfiguration of the mixture of dimers AB and CD into AD and CB, is followed by labeling each of the tiles with 0, 1, 2, and 3 4× hairpins labels and by imaging the dimer structures by atomic force microscopy. Subjecting the reconfigurable dimer mixtures to a collection of Mg2+-ion-dependent DNAzyme subunits and the substrates consisting of the ROX/BHQ2-modified substrate and the FAM/BHQ1-modified substrate leads to the triggered and programmed switchable operation, in the presence of appropriate fuel and antifuel strands. In the presence of the AB and CD mixture, the DNAzyme subunits cleaving the ROX/BHQ2-modified substrate is switched on, leading to the fluorescence of ROX. The reconfiguration of the AB and CD dimer mixture to the AD and CB dimer mixture leads to the assembly of the DNAzyme subunits that switches on the cleavage of the FAM/BHQ1-modified substrate and to the fluorescence of FAM. By the cyclic and reversible reconfiguration of the AB and CD dimer mixture to the AD and CB dimer mixture, in the presence of the appropriate fuel and antifuel strands, the switchable catalytic operation of two Mg2+-ion-dependent DNAzymes, leading to the fluorescence of ROX or FAM, is demonstrated.