Elemental imaging of leaves from the metal hyperaccumulating plant Noccaea caerulescens shows different spatial distribution of Ni, Zn and Cd

Elemental imaging using laser ablation inductively coupled plasma mass spectrometry was performed on whole leaves of the hyperaccumulating plant Noccaea caerulescens after treatments with either Ni, Zn or Cd. These detailed elemental images reveal differences in the spatial distribution of these three elements across the leaf and provide new insights in the metal ion homeostasis within hyperaccumulating plants. In the Zn treated plants, Zn accumulated in the leaf tip while Mn was co-localised with Zn suggesting similar storage mechanisms for these two metals. These data show a Zn concentration difference of up to 13-fold higher in the distal part of the leaf. Also, there was no correlation between the S and Zn concentrations providing further evidence against S-binding ligands. In contrast, Ni was more evenly distributed while a more heterogeneous distribution of Cd was present with some high levels on leaf edges, suggesting that different storage and transport mechanisms are used for the hyperaccumulation of these two metals. These results show the importance of correct sampling when carrying out subcellular localisation studies as the hyperaccumulated elements are not necessarily homogenously distributed over the entire leaf area. The results also have great implications for biotechnological applications of N. caerulescens showing that it may be possible to use the mechanisms employed by N. caerulescens to increase the Zn concentration in nutrient poor crops without increasing the risk of accumulating other toxic elements such as Ni and Cd.

Influence of calcium ion deposition on apatite-inducing ability of porous titanium for biomedical applications

In the present study, the influence of calcium ion deposition on the apatite-inducing ability of porous titanium(Ti) was investigated in a modified simulated body fluid (m-SBF). Calcium hydroxide (Ca(OH)₂) solutions with five degrees of saturation were used to hydrothermally deposit Ca ions on porous Ti with a porosity of 80%. Apatite-inducing ability of the Ca-ion-deposited porous Ti was evaluated by soaking them in m-SBF for up to 14 days. Scanning electron microscopy (SEM) and X-ray diffractometry (XRD) confirmed that a thin layer of calcium titanate (CaTiO₃)/calcium oxide (CaO) mixture with a nanostructured porous network was produced on porous Ti substrates after hydrothermal treatment at 200 °C for 8 h. X-ray photoelectron spectroscopy results demonstrated that the content of the Ca ions deposited on Ti and the thickness of the CaTiO₃/CaO layer increased with increasing saturation degree of the Ca(OH)₂ solution. The thickest (over 10 nm) CaTiO₃/CaO layer with the highest Ca content was achieved on the Ti treated in an oversaturated Ca(OH)₂ solution (0.2 M). SEM, XRD, transmission electron microscopy and Fourier transformed infrared spectroscopy analysis indicated that the porous Ti samples deposited with the highest content of Ca ions exhibited the best apatite-inducing ability, producing a dense and complete carbonated apatite coating after a 14 day soaking in m-SBF. The present study illustrated the validity of using Ca ion deposition as a pre-treatment to endow desirable apatite-inducing ability of porous Ti for bone tissue engineering applications.

The enhancement of lithium ion dissociation in polyelectrolyte gels on the addition of ceramic nano-fillers

Nano-particle oxide fillers including TiO₂, SiO₂ and Al₂O₃ have previously been shown to have a significant affect on the properties of both polymer and polymer gel electrolytes. In some cases, conductivity increases of one order of magnitude have been reported in crystalline PEO–base complexes. In this work, we report the effects of TiO₂ and SiO₂ on a poly(Li-AMPS)-based gel polyelectrolyte. Impedance spectroscopy and pfg-NMR spectroscopy indicates an increase in the number of available charge carriers with the addition of filler. An ideal amount of ceramic filler has been identified, with additional filler only saturating the system and reducing the conductivity below that of the pristine polyelectrolyte system. SEM micrographs suggest a model whereby the filler interacts readily with the sulfonate group; the surface area of the filler being an important factor.

A comparative study of secondary Ion emission from water ice under Ion bombardment by Au+, Au3+, and C60+

Secondary ion emission from water ice has been studied using Au⁺, Au₃⁺, and C₆₀⁺ primary ions. In contrast to the gas phase in which the spectra are dominated by the (H₂O)_nH⁺ series of ions, the spectra from ice using all three primary ions are principally composed of two series of cluster ions (H₂O)_nH⁺ and (H₂O)_n⁺. Dependent on the conditions, the unprotonated series can dominate the spectra. Since in the gas phase (H₂O)_n⁺ is unstable with respect to the formation of the protonated ion series, the presence of the solid must provide a means to stabilize their formation. The cluster ion yields under Au⁺ bombardment are very low and can be understood in terms of sputtering on the borderline between linear cascade and thermal spike behavior. There is a 10⁴ increase in yield across the whole spectrum compared to Au⁺ when Au₃⁺ and C₆₀⁺ species are used as primary ions. The character of the spectra differed between these two primary ions, but insights into the mechanism of secondary ion emission for both is discussed within an energy deposition framework provided by the fluid flow-based mesoscale energy deposition footprint (MEDF) model that predicts a cone-shaped zone of activation and emission. C₆₀⁺ differs from Au^₃+ in that it delivers its energy closer to the surface, and it is argued this has consequences for the cluster ion distribution and yield. Increasing the ion dose by sputtering suppresses the yield of (H₂O)_n⁺ and increases the yield of the protonated ions in the small cluster region, whereas the yield in the large cluster regime is suppressed significantly. The three primary ions show rather different behavior, and this is discussed in the light of the sputtering models. Finally, negative ion spectra including cluster ions have been observed for the first time. C₆₀⁺ delivers the highest yields, but these are less than 10 times the positive ion yields, probably because the O and OH fragment ions on which the clusters are based are easily neutralized by protons.

Growth of V2O5 nanorods from ball-milled powders and their performance in cathodes and anodes of lithium-ion batteries

The two-stage procedure of ball milling and annealing in air represents a prospective method of preparing nanorods of V₂O₅ with electrochemical properties suitable for the application in lithium-ion batteries. Commercially purchased V₂O₅ powder is milled in a ball mill as the first step of the synthesis. The as-milled precursor is subsequently annealed in air to produce the morphology of nanorods via solid-state recrystallization. We have recently investigated intermediate stages of the formation of nanorods, and this paper summarizes the synthesis method including the description of the current understanding of the growth mechanism. The obtained V₂O₅ nanorods have been assessed as an electrode material for both anodes and cathodes of lithium-ion batteries. When used in cathodes, the nanorods demonstrate a better retention of capacity upon cycling than that of the commercially available powder of V₂O₅. When used in anodes, the performances of nanorods and the reference V₂O₅ powder are similar to a large extent, which is related to a different operating mechanism of V₂O₅ in anodes. The experimentally observed capacity of V₂O₅ nanorods in an anode has stabilized at the level of about 450 mAh/g after few cycles.

Two-photon endomicroscopy for 3D imaging of cancer cells labelled with gold nanorods

Biofunctional nanorods are developed to specifically target cancer cells. The cervical cancer cells, HeLa cells, are labeled by these biofunctional gold nanorods. Those cancer cells can be detected by a multi-photon-excited photoluminescence endomicroscope, which proves that the cancers can be in vivo diagnosed by using biofunctional gold nanorods with nonlinear endomicroscopy.

Fabrication and biofunctionalization of selenium-polypyrrole core-shell nanoparticles for targeting and imaging of cancer cells

Selenium-polypyrrole core-shell nanoparticles are fabricated by an in-situ polymerization process and functionalized with transferrin for targeting and imaging of human cervical cancer cells. The shell thickness and chemical composition of the as-synthesized particles can be manipulated by controlling the precursor concentration. The presence of the polymer layer can greatly increase the thermal stability of the selenium nanoparticles. The presence of transferrin molecules on the surface of the core-shell nanoparticles can significantly enhance their cellular uptake. The tranferrin-conjugated core-shell nanoparticles can be potentially used for the targeting and imaging of cancer cells.

Trapping and imaging of embryonic organisms using dielectrophoresis

Development of dielectrophoretic (DEP) arrays for real-time imaging of embryonic organisms is described. Microelectrode arrays were used for trapping both embryonated eggs and larval stages of Antarctic nematode Panagrolaimus davidi. Ellipsoid single-shell model was also applied to study the interactions between DEP fields and developing multicellular organisms. This work provides proof-of-concept application of chip-based technologies for the analysis of individual embryos trapped under DEP force.

Trapping and imaging of micron-sized embryos using dielectrophoresis

Development of dielectrophoretic (DEP) arrays for real-time imaging of embryonic organisms is described. Microelectrode arrays were used for trapping both embryonated eggs and larval stages of Antarctic nematode Panagrolaimus davidi. Ellipsoid single-shell model was also applied to study the interactions between DEP fields and developing multicellular organisms. This work provides proof-of-concept application of chip-based technologies for the analysis of individual embryos trapped under DEP force.

Enactive research : transversal possibilities for expanding the imaging of science

This paper explores the notion of the expanded image as a transdisciplinary interaction between people and environments. In support of this proposition, images and imaging will be discussed through a series of transformative steps: from the diagram to the biogram and from the biogram to biotopology. Two research projects, exemplary of a transdisciplinary approach, inform the move to biotopology (the continuous surface of interactions tied to imaging practices): first, theories of enaction in cognitive science foreground co-selective processes and the precariousness of self- organizing systems and supply new ways of imaging body-environment relationships (Stewart et al 2010; Thompson 2007; and Varela et al 1993); and second, the procedural architecture of artist- turned-architects Arakawa and Gins foregrounds the reconfigurability of the co-selective process that becomes an enactive practice. These approaches suggest that if the image were expanded to include the intersection of the human organism’s behaviors, artifacts (such as images) and built- environments, then the ‘person’ whose myriad surfaces flicker towards future action, might become the best description of an expanded form of imaging, always in process and flickering towards future action. The many and non-locatable surfaces of person would defy disciplinary boundaries and interfere with habitual patterns of imaging. Ultimately, the aim of expanding imaging practices is to expand an embodied capacity to configure and reconfigure conceptual and material realms.

A fresh look at the validity of diffusion equations for modelling phosphorescence imaging of biological tissue

Phosphorescence lifetime imaging has become a widely used technique for tomographic oxygen imaging. The conventional model used to characterize photon transport in phosphorescence imaging is two coupled diffusion equations. On the premise that the total energy of excitation and phosphorescence photon flows must be conserved, we derive the diffusion equations in phosphorescence imaging and show that there must be an additional term to account for the transport of phosphorescent photons. This additional term accounts for the transport of phosphorescence photon energy density due to its gradients. The significance of this term in modelling phosphorescence in biological tissue is assessed.

The application of Cd Se/ZnS quantum dots and confocal laser scanning microscopy for three-dimensional imaging of nanfibrous structures

This paper reports a fast, accurate, and non-destructive three-dimensional imaging approach based on using quantum dots and confocal laser scanning microscopy to get three-dimensional images of internal pore structure of the nanofibrous materials. A practical method of making the fiber fluorescent using quantum dots was applied before three-dimensional imaging by confocal laser scanning microscopy. Fibrous scaffolds with different porosity parameters produced by electrospinning and their three-dimensional pore structure was evaluated by this approach. Furthermore, the introduced approach can be used to measure the pore interconnectivity of the scaffold