Pb Interactions Research Articles

Interaction of Pb -16Li melt with EUROFER97 under higher temperature and neutron irradiation

The behaviour of ferritic-martensitic steel EUROFER97 was evaluated after its exposure in a liquid Pb-16Li environment under neutron flux simulating the conditions of operating parameters of the HCLL test blanket module using a test train inserted into the LVR 15 research reactor in CV Řež. The interaction of the Pb-16Li alloy with neutron flux results in radioisotope formation due to transmutation reactions. The formation of tritium and polonium was measured and compared with calculated values. The Pb-16Li corrosion effect leads to dissolution of steel matric. Two reaction layers were observed on the exposed EUROFER97 surface. The first continuous surface layer is characterized by uneven thickness, the second subsurface layer confirms that dissolution of the metal matrix takes place along martensitic lath boundaries. The performed examinations proved that the mechanism of corrosion in the liquid melt was volume dissolution of steel.

Lead promotes abnormal angiogenesis induced by CCM3 gene defects via mitochondrial pathway.

Lead is one of the environmental pollutants with cardiovascular toxicity. The embryos are particularly sensitive to lead exposure, because it can move through the blood-placental barrier and the blood-brain barrier easily during embryonic development. Cerebral cavernous malformations 3 (CCM3) gene plays an important role in cardiovascular development, mainly affecting cell proliferation, differentiation and apoptosis. In this study, we established a blood vessel development model of mouse embryos in order to imitate human people with CCM3 genes defects and exposing to environment toxin Pb in utero. We would like to determine the interaction of Pb and CCM3 gene on vascular development, and to explore the mechanisms. We found that the yolk sac of CCM3 heterozygous mice embryo showed abnormal morphology at E11.5 after lead treatment comparing with wild type (WT) mice without lead exposure, meanwhile it showed more angiogenesis and vascular remodeling in the hematoxylin and eosin stained sections of the CCM3+/- yolk sac with lead exposure. We also found that the similar effect of Pb and CCM3 gene on mitochondrial DNA (mtDNA) copy number in vivo and in vitro. Mitochondrial morphology and function also changed in primary human umbilical vein endothelial cells after lead exposure. Besides, it was found that the HIF-1α and TFAM which have close relationship with mtDNA biogenesis showed similarly increasing messenger RNA expression in both human and mouse-derived primary cells with lead treated and CCM3 gene knockout. All of the above results indicated that lead and CCM3 might damage endothelial cells through mitochondria pathway and eventually both affected angiogenesis.

In vitro assessment of the toxicity of lead (Pb2+) to phycocyanin

This work reports the influence of lead (Pb2+) on fluorescence characteristics and protein structure of phycocyanin molecules experimentally in vitro. The fluorescence intensity decreases with the increasing concentration of Pb2+ from 0 to 5 × 10−5 mol L−1, showing the fluorescence quenching of phycocyanin by Pb2+. The quenching process is suggested to be static regarding the calculation results and the experimental results of time-resolved fluorescence decay profiles. The synchronous fluorescence spectra show that the effect of Pb2+ on the Tyr residues of phycocyanin is more significant than the Trp residues. The forming of aggregation by the interaction of Pb2+ with phycocyanin molecules is suggested from the results of resonance light scattering spectra. The UV–Vis spectra of the protein skeleton of phycocyanin have a red-shift of about 10 nm with increasing the Pb2+ concentration from 0 to 5 × 10−5 mol L−1, indicating a change in the protein skeleton and its secondary structure. With the increasing Pb2+ concentration, the two negative peaks (209 nm and 218 nm) on circular dichroism spectra become smaller, showing a decrease of the α-helix structure. These results may give people a deeper understanding of that how the heavy metal (Pb2+) can affect the chemo-physical properties of phycocyanin.

Contrasting freezeouts in large versus small systems

We study the data on mean hadron yields and contrast the chemical freezeout (CFO) conditions in p+p, p+Pb and Pb+Pb at the Large Hadron Collider energies. We study several schemes for freezeout that mainly differ in the way strangeness is treated: i. Strangeness freezes out along with the non-strange hadrons in complete equilibrium (1CFO), ii. Strangeness freezes out along with non-strange hadrons with an additional parameter accounting for non-equilibrium production of strangeness (1CFO+), and iii. Strangeness freezes out earlier than non-strange hadrons and in thermal equilibrium (2CFO). A comparison of the chisquares of the fits indicate a dependence of the freezeout scheme on the system size. The minimum bias p+p and different centralities of p+Pb and peripheral Pb+Pb data prefer 1CFO with approaching unity as we go from p+p to central p+Pb and peripheral Pb+Pb. On the other hand, the mid-central to central Pb+Pb data prefer 2CFO over 1CFO+. Such system size dependence of the freezeout scheme could be an indication of the additional interaction in Pb+Pb over p+Pb and p+p.

Salicylic acid accumulation as a result of Cu, Zn, Cd and Pb interactions in common reed (Phragmites australis) growing in natural ecosystems

Common reed (Phragmites australis (Cav.) Trin. ex Steud.) plants were harvested from four natural water ecosystems of the Bogdanka river catchment (Poznań, Poland) four times throughout the 2014 vegetative season. Over the year, average metal contents followed different decreasing trends according to the analyzed tissue: Zn > Cu ≈ Pb > Cd (rhizomes) and Zn > Pb > Cu > Cd (leaves), and mean translocation ratios (leaves/rhizomes) were found as follows: 0.93, 0.70, 0.65, 0.40 for Zn, Pb, Cd and Cu, respectively. Metal content increased gradually during the growing season, and in the case of Cu, Cd and Pb exceeded the upper limit of average concentration detected in plants from natural ecosystems. However, the content of salicylic acid did not follow the increase of metal accumulation. In rhizomes, the highest production of the metabolite was observed in May and reached 324 ng g−1 fresh weight (FW) (mean value). Afterwards, a significant drop to 50 ng g−1 FW was observed. Simultaneously, the highest values of total salicylic acid in P. australis leaves were observed in July and accompanied the intensive development of the aboveground biomass of the plant (11.3 µg g−1 FW–mean value). Subsequently, its content in leaves showed a significant decrease down to 2.1 µg g−1 FW in November. Multivariate regression analysis revealed significant interactions between analyzed metals influencing the plant response to metal-derived stress. Cu and Zn showed antagonistic properties considering their uptake and the induction of salicylic acid biosynthesis, whereas non-essential metals (Pb and Cd) acted similarly and stimulated the formation of salicylic acid glucoside.

Rapid adsorption of Pb, Cu and Cd from aqueous solutions by β-cyclodextrin polymers

Removing heavy metals from aqueous solutions has drawn more and more attentions these years because of their serious global health challenge to human society. To develop an adsorbent with low-cost and high-efficiency for removal of heavy metals (HMs), β-cyclodextrin (β-CD) polymers crosslinked with rigid aromatic groups were prepared and used for lead (Pb), copper (Cu) and cadmium (Cd) removal for the first time. The negatively charged β-CD polymers with large BET surface area were suitable to be used in HMs adsorption. The adsorption process completed in 5min was well fit by Freundlich isotherm model and pseudo-second-order model. The intraparticle diffusion model was also appropriate to describe the adsorption of Pb, Cu and Cd on β-CD polymer. The maximum of adsorption capacities at 25°C for Pb, Cu and Cd were 196.42, 164.43 and 136.43mg/g when the initial concentration was 200mg/L. The HMs adsorption process on the surface of β-CD polymer was an endothermic and spontaneous process. Both of the electrostatic interaction and distribution of Pb, Cu and Cd species influenced the adsorption process at different pH values. The order of removal efficiencies in multi-component adsorption for the three metal ions were Pb > Cu > Cd. The adsorption mechanisms were H+ ions on hydroxyl groups exchanged with heavy metal ions and electrostatic interactions. This study indicated that β-CD polymers could be developed into effective adsorbents for rapid removal of heavy metals.

Ca-alginate as a support matrix for Pb(II) biosorption with immobilized biofilm associated extracellular polymeric substances of Pseudomonas aeruginosa N6P6

The contribution of immobilized biofilm associated extracellular polymeric substances (EPS) of a marine bacterium Pseudomonas aeruginosa N6P6 in sequestering Pb(II) was investigated. The interaction between extracellular polymeric substances (EPS) and Pb(II) during the sorption process of Pb(II) was investigated using three-dimensional excitation-emission matrix (3D-EEM) and atomic absorption spectroscopy. 3D-EEM showed that the intensities of protein (PN) like fluorophores decreased during the Pb(II) sorption process. The interaction of Pb(II) and EPS fluorophore occurs spontaneously (ΔG=−13.79kJ/K/mol) at 25°C with a binding constant value of 5.67 lmol−1. Through comparison of Pb(II) sequestration on immobilized live biomass and pristine alginate beads, we found that immobilized biofilm derived EPS contribute significantly to Pb(II) sequestration. The biosorption was studied by varying pH from 3 to 8 and initial Pb(II) concentration from 100 to 600mgl−1 to find out the optimized conditions for maximum Pb(II) removal by various biosorbents. The Pb(II) biosorption capacity of the EPS alginate beads was significantly higher (416.67mgg−1) than that of alginate biomass beads (232.55mgg−1) and pristine alginate beads (120.48mgg−1) (P<0.05; One way ANOVA and Tukey’s HSD test). The maximum adsorption of Pb(II) on all the prepared biosorbents were observed at pH 6. Two equilibrium models, Langmuir and Freundlich, were used for computing the efficiency of Pb(II) binding by the developed biosorbents. The adsorption isotherms, Langmuir and the Freundlich type models were found to exhibit good fit (R2=0.99) to the experimental data. The reusability of the EPS alginate biosorbent was studied by Pb adsorption (68.33%) and desorption (66.8%) from contaminated water after three adsorption/desorption cycle.

Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at [formula omitted] with the CMS experiment

The cross section for coherent J/ψ photoproduction accompanied by at least one neutron on one side of the interaction point and no neutron activity on the other side, Xn0n, is measured with the CMS experiment in ultra-peripheral PbPb collisions at sNN=2.76TeV. The analysis is based on a data sample corresponding to an integrated luminosity of 159μb−1, collected during the 2011 PbPb run. The J/ψ mesons are reconstructed in the dimuon decay channel, while neutrons are detected using zero degree calorimeters. The measured cross section is dσXn0ncoh/dy(J/ψ)=0.36±0.04(stat)±0.04(syst) mb in the rapidity interval 1.8<|y|<2.3. Using a model for the relative rate of coherent photoproduction processes, this Xn0n measurement gives a total coherent photoproduction cross section of dσcoh/dy(J/ψ)=1.82±0.22(stat)±0.20(syst)±0.19(theo) mb. The data strongly disfavor the impulse approximation model prediction, indicating that nuclear effects are needed to describe coherent J/ψ photoproduction in γ+Pb interactions. The data are found to be consistent with the leading twist approximation, which includes nuclear gluon shadowing.

Nuclear modification of light flavour and strangeness at LHC energies with ALICE

Thanks to its unique particle identification capabilities the ALICE detector is able to identify light-flavour, strange and multi-strange hadrons, including π, K, p, , Λ, Ξ and Ω, over a wide range of transverse momentum, from pp and p–Pb interactions up to central Pb–Pb collisions. The latest results on the nuclear modification factor, RAA, as a function of the Pb–Pb collision centrality, is shown for various particle specie at centre-of-mass energy. For each particle specie, the RAA is compared with the nuclear modification factors RpA in p-Pb collisions to asses the presence of hot nuclear matter effects affecting the high-pΤ particle production in Pb–Pb collisions. The results on the RAA of charged hadrons at , the highest energy ever reached in the laboratory for heavy-ion collisions, is also shown.

Understanding the roles of Na2S and Pb(II)in the flotation of hemimorphite

The mechanisms involved in hemimorphite flotation using the “Na2S-Pb(II)-xanthate” process, including pre-sulfurization using sodium sulfide, activation by lead cations and subsequent flotation using a butyl xanthate collector, were studied. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS), and X-ray diffraction (XRD) characterization were conducted to identify the mechanism of interaction of Na2S and Pb(II) with hemimorphite particles. The results indicated that the “Na2S-Pb(II)-xanthate” process is an effective method for the flotation of hemimorphite, and the maximum recovery of the hemimorphite concentrate increased from 40% to 90%. Hydrosulfide ions were chemisorbed or participated on the hemimorphite ore surface, and a layer of ZnS was formed. The XRD results indicated that the ZnS layer was amorphous or poorly crystallized. PbS was generated by the interaction of Pb(II) with ZnS through an ion-exchange mechanism, which was verified by XPS, SEM-EDS and XRD. The XRD study indicated that the new PbS phase formed on the hemimorphite ore surface was well-crystallized “synthetic galena” with good floatability, which is critical for the potential application of hemimorphite flotation using the “Na2S-Pb(II)-xanthate” process.

The modification of rectorite with carbon layers and trisodium trimetaphosphate for the removal of Pb2 +

At the presence of rectorite (Rec), starch was treated with hydrothermal carbonization to fabricate carbon layer with many oxygen containing groups on the surface of Rec layer, which were further reacted with trisodium trimetaphosphate (STMP) to introduce phosphate ester groups on Rec. The obtained RecCPN were used to remove heavy metal ions from aqueous solution. The adsorption kinetics and isotherms could be described with the pseudo- second-order model and the Langmuir model. The maximum monolayer adsorption capacities could reach 258.40mg/g for RecCPN at pH5 and 303K, in which the Pb2+ adsorption processes was spontaneous. The positive values of ΔH0 indicated that the interaction of Pb2+ with phosphate ester groups was endothermic. RecCPN still exhibited the good adsorption capacity in the adsorption-desorption cycles. In addition, RecCPN showed advantageous selectivity towards Pb2+ over other metal ions (Cu2+, Ni2+, Co2+ and Cd2+) and still removed above 90% Pb2+ at the initial trace Pb2+ concentration (0.5mg/L).

Synthesis of molybdenum disulfide/reduced graphene oxide composites for effective removal of Pb(II) from aqueous solutions

In this work, a facile method was adopted to synthesize molybdenum disulfide/reduced graphene oxide (MoS2/rGO) composites through an l-cysteine-assisted hydrothermal technique. The as-prepared MoS2/rGO composites were firstly applied as adsorbents for efficient elimination of Pb(II) ions. Batch adsorption experiments showed that the adsorption of Pb(II) on MoS2/rGO followed pseudo-second-order kinetic model well. The adsorption of Pb(II) was intensely pH-dependent, ionic strength-dependent at pH < 9.0 and ionic strength-independent at pH > 9.0. The presence of humic acid (HA) enhanced Pb(II) adsorption obviously. The MoS2/rGO composites exhibited excellent adsorption capacity of 384.16mgg−1 at pH 5.0 and T=298.15K, which was superior to MoS2 (279.93mgg−1) and many other adsorbents. The thermodynamic parameters suggested that the adsorption process of Pb(II) on MoS2/rGO composites was spontaneous (ΔGθ<0) and endothermic (ΔHθ>0). The interaction of Pb(II) and MoS2/rGO was mainly dominated by electrostatic attraction and surface complexation between Pb(II) and oxygen-containing functional groups of MoS2/rGO. This work highlighted the application of MoS2/rGO as novel and promising materials in the efficient elimination of Pb(II) from contaminated water and industrial effluents in environmental pollution management.

Transverse momentum distribution of primary charged particles in p–Pb interactions at forward pseudorapidity at LHC energies

Transverse momentum distributions of primary charged particles have been studied using simulated data from the HIJING 1.0 event generator in the minimum bias p–Pb collisions at [Formula: see text] = 0.9, 1.8, 2.76 and 5.02[Formula: see text], in the two forward pseudorapidity ([Formula: see text]) regions: [Formula: see text] and [Formula: see text] and in the transverse momentum range of [Formula: see text]. The simulated data in the pseudorapidity region of [Formula: see text] at 5.02[Formula: see text] depicts some differences in the region of [Formula: see text] [Formula: see text] 2[Formula: see text] when compared with CMS data. Model shows systematically higher values than the experimental measurements pointing out absorption effect for the experimental data. It is also observed that with increasing rapidity interval from [Formula: see text] to [Formula: see text] observed differences for the behavior of the transverse momentum distributions are shifted to high transverse momentum region. The nuclear modification factor as a function of transverse momentum is constructed using the HIJING 1.0 code. With incident energy, the values of nuclear modification factor increase, for 0.9 and 1.8 [Formula: see text], the distributions seem to increase, but for 2.76 and 5.02 [Formula: see text], the distributions look flat. Numerically, the value of nuclear modification factor increases with the increase in the number of jets. This result shows that for the considered more forward pseudorapidiry area, the influence of the incident energy dominates and this is the reason that main results in the areas are connected with the leading particles.

Effects of carbon nanotube and biochar on bioavailability of Pb, Cu and Sb in multi-metal contaminated soil.

This study examined the effects of carbon nanotube and biochar on the bioavailability of Pb, Cu and Sb in the shooting range soils for developing low-cost remediation technology. Commercially available multi-walled carbon nanotube (MWCNT) and biochar pyrolyzed from soybean stover at 300°C (BC) at 0.5, 1 and 2.5% (w w-1) were used to remediate the contaminated soil in an incubation experiment. Both DTPA (bioavailable) and TCLP (leaching) extraction procedures were used to compare the metal/loid availability and leaching by the amendments in soil. The addition of BC was more effective in immobilizing mobile Pb and Cu in the soil than that in MWCNT. The BC reduced the concentrations of Pb and Cu in the soil by 17.6 and 16.2%, respectively. However, both MWCNTs and BC increased Sb bioavailability by 1.4-fold and 1.6-fold, respectively, in DTPA extraction, compared to the control. The toxicity characteristic leaching procedure (TCLP) test showed that the leachability of Pb in the soil amended with 2.5% MWCNT was 1.3-fold higher than that the unamended soil, whereas the BC at 2.5% decreased the TCLP-extractable Pb by 19.2%. Precipitation and adsorption via electrostatic and π-π electron donor-acceptor interactions were postulated to be involved in the interactions of Pb and Cu with surfaces of the BC in the amended soils, whereas ion exchange mechanisms might be involved in the immobilization of Cu in the MWCNT-amended soils. The application of BC derived from soybean stover can be a low-cost technology for simultaneously immobilizing bioavailable Pb and Cu in the shooting range soils; however, neither of amendments was effective in Sb immobilization.

In situ reactive zone with modified Mg(OH)2 for remediation of heavy metal polluted groundwater: Immobilization and interaction of Cr(III), Pb(II) and Cd(II)

Mg(OH)2 dissolves slowly and can provide a long-term source of alkalinity, thus a promising alternative reagent for the in situ remediation of heavy metal polluted groundwater. However, the application of Mg(OH)2 on in situ reactive zone (IRZ) for heavy metal polluted groundwater has never been investigated. In this study, the behaviors of heavy metals in a Mg(OH)2 IRZ were monitored for 45d. The heavy metals show a sequential precipitation by modified Mg(OH)2 due to the difference of Ksp. Column tests were conducted to investigate the temporal and spatial distribution of heavy metals in Mg(OH)2 IRZ and evaluate the stabilization effect for multi-heavy metal polluted groundwater. Experimental results indicate that there exist interactions between different heavy metals, and their zoning distribution is attributed either to the competitive adsorption onto porous media (control column) or to the sequential precipitation of heavy metal ions (IRZ column). In contrast with the control column, heavy metal contaminated area in Mg(OH)2 IRZ significantly shrinks. According to the chemical speciation analysis, when water containing Pb(II), Cd(II) and Cr(III) flows through Mg(OH)2 IRZ, exchangeable fraction of total concentration significantly reduce and the proportion of carbonate and Fe/Mn oxides fraction increase, indicating the decrease of their mobility and toxicity.

Morphological Evolution of Block Copolymer Particles: Effect of Solvent Evaporation Rate on Particle Shape and Morphology.

Shape and morphology of polymeric particles are of great importance in controlling their optical properties or self-assembly into unusual superstructures. Confinement of block copolymers (BCPs) in evaporative emulsions affords particles with diverse structures, including prolate ellipsoids, onion-like spheres, oblate ellipsoids, and others. Herein, we report that the evaporation rate of solvent from emulsions encapsulating symmetric polystyrene-b-polybutadiene (PS-b-PB) determines the shape and internal nanostructure of micron-sized BCP particles. A distinct morphological transition from the ellipsoids with striped lamellae to the onion-like spheres was observed with decreasing evaporation rate. Experiments and dissipative particle dynamics (DPD) simulations showed that the evaporation rate affected the organization of BCPs at the particle surface, which determined the final shape and internal nanostructure of the particles. Differences in the solvent diffusion rates in PS and PB at rapid evaporation rates induced alignment of both domains perpendicular to the particle surface, resulting in ellipsoids with axial lamellar stripes. Slower evaporation rates provided sufficient time for BCP organization into onion-like structures with PB as the outermost layer, owing to the preferential interaction of PB with the surroundings. BCP molecular weight was found to influence the critical evaporation rate corresponding to the morphological transition from ellipsoid to onion-like particles, as well as the ellipsoid aspect ratio. DPD simulations produced morphologies similar to those obtained from experiments and thus elucidated the mechanism and driving forces responsible for the evaporation-induced assembly of BCPs into particles with well-defined shapes and morphologies.

Toxic Metal Ions Promote Self-Association and Replace Structural Zinc Ions in the Regulatory Region of Protein Kinase C

Protein Kinase C (PKC) isoenzymes are a family of kinases that control cell proliferation, migration, and apoptosis. The hallmark of PKC activation is their translocation to lipid membranes that occurs in response to Ca2+ and diacylglycerol. Previous studies have shown that PKC activity is modulated by toxic metal ions such as Pb2+ and Cd2+. Our objective was to understand the effect of these metal ions on the structure and function of the membrane-binding regulatory region of PKC. Our efforts focused on the PKCα region that consists of two peripheral membrane-binding domains, C1B and C2. Using a combination of biophysical techniques, we demonstrate that interactions of Pb2+ and Cd2+ with C1B-C2 have profound and distinct consequences for the biophysical and functional properties of this region. While both Cd2+ and Pb2+ can spontaneously replace structural Zn2+ ions in C1B, NMR spectroscopy revealed that only Cd2+ was able to support the proper fold and ligand-binding function of the protein. In addition, Cd2+ promotes the formation of well-defined C1B-C2 oligomers that we were able to detect and characterize using small-angle X-ray scattering experiments and negative-stain electron microscopy. In contrast to Cd2+, Pb2+ cannot support the proper fold of C1B but acts successfully as a functional surrogate of Ca2+ in driving protein-membrane association. Our work demonstrates the potential diversity of responses of signaling proteins to toxic metal ions and suggests that molecular mechanisms of Pb2+ and Cd2+ toxicity are distinct. This work was supported by Welch Foundation grant A-1784, NSF CAREER award CHE-1151435, and NIH grant R01 GM108998.

Control of electro‐osmotic flow by mixed polymer brushes: Molecular dynamics simulations

Molecular dynamics simulations of electro‐osmotic flow through a channel coated by a mixed polymer brush reveal the modulation of electro‐osmotic flow. The mixed polymer brush consists of two types of neutral chains, denoted as PA and PB chains, respectively. The effect of the interaction strength between PA and PB monomers on fluid transport is studied. It was found that the PA‐PB interaction plays an important role in controlling the flow. The mixed polymer brush adopts a layered structure owing to the difference in solvent‐polymer interactions. Stronger shear force from the solvent flow leads to larger extension of polymer chains on the top layer (or PA chains). Such layering structure also causes different coupling between polymer conformational dynamics and fluid dynamics. At high grafting densities, there are remarkable differences in the velocity profiles for different PA‐PB interactions. For repulsive and attractive interactions, the increase of grafting density leads to reduced fluid transport. However, when the attraction between PA and PB interactions becomes stronger, the flow behavior is more complicated depending on the grafting density. Our simulation results indicate the change of ionic distribution induced by the conformational transition due to the PA‐PB interaction has significant contributions to the flow controlling. POLYM. ENG. SCI., 57:1293–1300, 2017. © 2017 Society of Plastics Engineers

Germination, Physiological Responses and Gene Expression of Tall Fescue (Festuca arundinacea Schreb.) Growing under Pb and Cd.

Cadmium (Cd) and lead (Pb) are recognized as the most toxic metal ions due to their detrimental effects not only to plants, but also to humans. The objective of this study was to investigate the effects of Cd and Pb treatments on seed germination, plant growth, and physiological response in tall fescue (Festuca arundinacea Schreb.). We employed six treatments: CK (nutrient solution as control), T1 (1000 mg L-1 Pb), T2 (50 mg L-1 Cd), T3 (150 mg L-1 Cd), T4 (1000 mg L-1 Pb+50 mg L-1 Cd), T5 (1000 mg L-1 Pb+150 mg L-1 Cd). Antagonistic and synergistic actions were observed in tall fescue under Pb and Cd combined treatments. Under low Cd, plants exhibited higher relative germination rate, germ length, VSGR, catalase (CAT) and peroxidase (POD) activities. Additionally, in the shoots, the gene expression level of Cu/Zn SOD, FeSOD, POD, GPX, translocation factors, MDA, EL, and soluble protein contents were reduced under Pb stress. Conversely, under high Cd level, there was a decline in NRT, Pb content in shoots, Pb translocation factors, CAT activity; and an increase in VSGR, Pb content in roots, gene expression level of Cu/ZnSOD and POD in tall fescue exposed to Pb2+ regimes. On the other hand, tall fescue plants treated with low Cd exhibited lower relative germination rate, germination index, germ length, NRT, Cd content in roots. On the other hand there was higher Cd content, Cd translocation factor, CAT and POD activities, and gene expression level of Cu/Zn SOD, FeSOD, POD, GPX under Pb treatment compared with single Cd2+ treatment in the shoots. However, after high Cd exposure, plants displayed lower NRT, Cd content, CAT activity, and exhibited higher Cd contents, Cd translocation factor, MDA content, gene expression level of Cu/ZnSOD and GPX with the presence of Pb2+ relative to single Cd2+ treatment. These findings lead to a conclusion that the presence of low Cd level impacted positively towards tall fescue growth under Pb stress, while high level of Cd impacted negatively. In summary, antioxidant enzymes responded to Cd and Pb interaction at an early stage of exposure, and their gene expression profiles provided more details of the activation of those systems.

Predicting Yield and Stability Analysis of Wheat under Different Crop Management Systems across Agro-Ecosystems in India

The objectives of the study were as follows: 1) to evaluate the GxExM for wheat genotypes; 2) to predict yield performance and identify high stable wheat genotypes in different management practices; and 3) to make genotype-specific management and high performing genotype recommendations within and across agro-ecological regions. A diverse set of twenty-one genotypes was evaluated over three years (2012, 2013 and 2014) under two levels of crop management practices (CT and ZT) across three agro-ecological regions (BR, MP and PB) of India in replicated trials. Data were analyzed with SASGxE and RGxE programs using SAS and R programming languages, respectively. Across and within a location(s), the pattern of GxExM and GxMxY interactions (respectively) among univariate and multivariate stability statistics, grouping of genotypes in divisive clusters and estimates (with a prediction interval) of genotype varied in management practice CT and ZT. Across locations, the genotypes “Munal” and “HD-2967” were the best performers and high stable in CT and ZT, respectively. Genotypes “HD-2824” and “DPW-621-50”, and “Munal” may serve as diverse parents for developing high quality, climate smart, locally adapted genotypes for BR in CT and ZT, respectively. Genotypes “HD-2932”, “BAZ” and “JW-3288”, and “GW-322” and “HD-2967” are suitable for developing locally adapted stress tolerant genotypes for MP in management practices CT and ZT, respectively. Relatively small GxM and GxExM interactions in PB preclude in making definitive conclusions.