Ex situ electrochemical sodiation/desodiation observation of Co₃O₄ anchored carbon nanotubes: a high performance sodium-ion battery anode produced by pulsed plasma in a liquid

Liquid plasma, produced by nanosecond pulses, provides an efficient and simple way to fabricate a nanocomposite architecture of Co3O4/CNTs from carbon nanotubes (CNTs) and clusters of Co3O4 nanoparticles in deionized water. The crucial feature of the composite's structure is that Co3O4 nanoparticle clusters are uniformly dispersed and anchored to CNT networks in which Co3O4 guarantees high electrochemical reactivity towards sodium, and CNTs provide conductivity and stabilize the anode structure. We demonstrated that the Co3O4/CNT nanocomposite is capable of delivering a stable and high capacity of 403 mA h g(-1) at 50 mA g(-1) after 100 cycles where the sodium uptake/extract is confirmed in the way of reversible conversion reaction by adopting ex situ techniques. The rate capability of the composite is significantly improved and its reversible capacity is measured to be 212 mA h g(-1) at 1.6 A g(-1) and 190 mA h g(-1) at 3.2 A g(-1), respectively. Due to the simple synthesis technique with high electrochemical performance, Co3O4/CNT nanocomposites have great potential as anode materials for sodium-ion batteries.

The influence of unburnt patches and distance from refuges on post-fire bird communities

Predicting the response of faunal communities to fire presents a challenge for land managers worldwide because the post-fire responses of species may vary between locations and fire events. Post-fire recovery can occur via nucleated recovery from in situ surviving populations or by colonization from ex situ populations. Fine-scale spatial patterns in the patchiness of fires and the proximity of burnt sites to source populations may contribute to both the variability in post-fire responses and the processes by which populations recover. We examined the avifauna at recently burnt sites within extensive semi-arid shrublands of south-eastern Australia, including 72 sites < 5 years since fire and 26 sites 10 years since fire. Study sites represented a gradient of increasing distance from ‘unburnt’ vegetation (i.e. > 27 years since fire) and varied in the presence or absence of small (25–900 m2) unburnt patches of vegetation. For sites < 5 years since fire, species richness was higher at sites closer to unburnt vegetation and at sites containing unburnt patches. These patterns were no longer evident at sites of 10 years since fire. The probability of occurrence of three of seven bird species modelled decreased with increasing distance to unburnt vegetation, but this pattern was evident only at sites burnt uniformly. One species was found almost exclusively at patchily burnt sites. These results are consistent with the hypothesis that proximity to unburnt vegetation enhances post-fire occupancy, and that colonization from ex situ populations is an important process for post-fire recovery of avifauna. Additionally, small unburnt patches enhance the rapid recovery of assemblages post-fire. These patterns are important for understanding the dynamics of post-fire population recovery. We recommend that management of fire for ecological purposes should explicitly consider the role that the spatial attributes of fires play in determining the post-fire community.

Large unburnt areas, not small unburnt patches, are needed to conserve avian diversity in fire-prone landscapes

Mitigating the impacts of large-scale fires on biodiversity is becoming increasingly important as their frequency increases. In response, fire managers have engaged with the concept that retaining small unburnt residual areas of vegetation within extensively burnt landscapes may facilitate biodiversity conservation. However, it remains uncertain how the size and isolation of these unburnt residuals influence faunal distributions, persistence and recovery following fire. We used a replicated observation study to test bird responses to the size and isolation of unburnt residuals in a mallee woodland area recently burnt by a 28 000 ha wildfire in southern Australia. The scale of our study provided a rare opportunity to consider the responses of large mobile organisms to fire-induced habitat fragmentation. Within five replicated spatial blocks, we crossed two levels of isolation with large (5-7 ha) and small (1-3 ha) unburnt patches and matrix sites burnt 5 years previously. We compared these site types to six continuous (non-fragmented) unburnt sites. We surveyed each site on eight occasions. Most birds occurred more frequently in unburnt habitat beyond the extent of the fire. Bird responses to the availability and spatial distribution of unburnt remnants within the fire were largely influenced by their ability to use the recently burnt matrix. Occurrence of five species was higher in unburnt residuals when more of the landscape within 500 m was burnt. A fire refuge effect may be likely for two competitive species that occurred more frequently in unburnt residuals than in the burnt matrix or continuous unburnt habitat. For the weebill, recolonization following fire was likely to occur gradually over time from ex situ sources. Synthesis and applications. To maintain avian diversity in fire-prone landscapes, our results suggest a need to shift management focus from creating networks of small unburnt patches towards preserving large, intact areas of habitat. However, five species common to the burnt matrix preferentially selected residual patches when unburnt resources were locally scarce. Therefore, to benefit birds, land managers should limit the extent of applied burns and use narrow burns. When planning large burns, practitioners should consider that a number of species will remain absent from the landscape for several decades.

Slip during tension testing of Mg-3A1-1Zn sheet

The activation of slip and twinning deformation modes in Mg-3Al-1Zn alloy was investigated by means of both in-situ and ex-situ methods at ambient temperature using electron back scattering diffraction (EBSD). The results confirm the importance of non-basal slip and c-axis compression double twinning. During tensile deformation of rolled sheet, 63% of the observed slip traces were ascribed to prismatic slip, 33% to basal slip and 4% to <c+a> slip. Prismatic slip was frequently observed in grain interiors. The density of twinning was quantified in samples tested along transverse, extrusion and rolling directions at failure. The values in the range of 0.02-0.18 twins per square micron were found depending on sample orientation. The results show the effect of twinning on failure.

Self-assembly and film stability of a micelle of a single-chain quaternary ammonium amphiphile containing azobenzene on mica

The self-assembling behavior of a single-chain quaternary ammonium amphiphile bearing azobenzene (C₁₂AzoC₆N⁺) on freshly cleaved mica sheet has been investigated by atomic force microscopy (AFM) method. Confocal microscopic Raman spectra confirm the adsorption of the self-assembled monolayer structure. Ex-situ AFM reveals that C₁₂AzoC₆N⁺ forms branch-like stripes indicating the fusion and reorganization of the micelles during drying in air as the in-situ AFM has revealed that surfactant forms spherical micelles on the mica surface. The nano-sized surface structure is strongly dependent on the change of molecular structure, which resulted from photo-induced isomerization. The nano-sized stripe is quite stable even being annealed at 90 °C for 4 h.

The miscibility of poly(d,l-lactide-co-glycolide) with amphiphilic molecules and the interaction of their mixtures with DNA at air/water interface

The miscibility of poly(d,l-lactide-co-glycolide) (PLG) with three amphiphilic molecules and the interaction of the PLG/surfactant mixtures with DNA at air/water interface are investigated by π-A isotherms, Brewster angle microscopy (BAM) and atomic force microscopy (AFM) techniques. The π-A isotherms of the PLG mixtures with cationic C12AzoC6PyBr, and C12AzoC6N(CH3)3Br, are quite different from the π-A isotherm of pure PLG on water subphase. In contrast to the case, the π-A isotherm of PLG mixed with nonionic C12AzoC6OPy is almost identical to the pure PLG except some increasing of molecular area. Similar phenomena are observed on DNA subphase. The in situ BAM and ex situ AFM observations demonstrate that the dispersion of PLG at air/water interface becomes good when it mixes with the two cationic surfactants, whereas quite poor due to the phase separation when it mixes with the nonionic amphiphilic molecule. Based on these results we conclude that the cationic surfactants can affect the conformation change of PLG at air/water interface and figure a well miscibility with polymer whereas the nonionic amphiphilic molecule presents poor miscibility. In addition, the even mixing of the PLG and the cationic surfactants is favorable for the adsorption to DNA more effectively.

Monolayer behavior of a pyridyl head-group-containing amphiphile and its miscibility with poly(D,L-lactide-co-glycolide) on different pH subphase

In this paper, we investigated the Langmuir film and Langmuir–Blodgett (LB) monolayer film of a nonionic amphiphilic molecule, 4-(6-p-pyridyloxyl)hexyloxyl-4′-dodecyloxylazobenzene (C12AzoC6Py) and its mixture with poly(d,l-lactide-co-glycolide) (PLG) at different subphase pH values (2.0, 2.6, 3.3, 4.4, and 6.5, respectively) by surface pressure–area (π–A) isotherms, in situ interface Brewster angle microscopy (BAM), and ex situ atomic force microscopy (AFM). For pure C12AzoC6Py, its π–A isotherms display a plateau when the subphase pH value is lower than 3.0. The pressure of the plateau increases with the decrease of pH until 2.0. Over the plateau, the π–A isotherms become almost identical to the one under neutral conditions. The appearance of such a plateau can be explained as the coexistence of protonation and unprotonation of pyridyl head groups of the employed amphiphile. In contrast to the homogeneous surface morphology of pure C12AzoC6Py near the plateau by BAM observation, the surface in the case of its mixing with PLG exhibits a dendritic crystalline state under low surface pressure at subphase pH lower than 3.0. The crystalline state becomes soft and gradually melts into homogeneous aggregates with surface pressure increasing to a higher value than that of the plateau. Meanwhile, the hydrolysis of PLG in the mixture system at the interface has been affirmed to be restrained to a very large extent. And the PLG was believed to be compelled to the up layer of the LB film due to the phase separation, which is examined by AFM. Based on the experimental results, the corresponding discussion was also performed.

Chemisorbed and physisorbed Structures for 1,10-Phenanthroline and Dipyrido[3,2-a:2',3'-c]phenazine on Au(111)

Scanning tunneling microscopy (STM) images of 1,10-phenanthroline (PHEN) and dipyrido[3,2-a:2‘,3‘-c]phenazine (DPPZ) on Au(111) are recorded using both in situ and ex situ techniques. The images of PHEN depict regimes of physisorption and chemisorption, whereas DPPZ is only physisorbed. All physisorbed structures are not pitted and fluctuate dynamically, involving aligned (4 × 4) surface domains with short-range (ca. 20 molecules) order for PHEN but unaligned chains with medium-range (ca. 100 molecules) order for DPPZ. In contrast, the chemisorbed PHEN monolayers remain stable for days, are associated with surface pitting, and form a (4 × √13)R46° lattice with long-range order. The density of pitted atoms on large gold terraces is shown to match the density of chemisorbed molecules, suggesting that gold adatoms link PHEN to the surface. For PHEN, chemisorbed and physisorbed adsorbate structures are optimized using plane-wave density-functional theory (DFT) calculations for the surface structure. Realistic binding energies are then obtained adding dispersive corrections determined using complete-active-space self-consistent field calculations using second-order perturbation theory (CASPT2) applied to cluster-interaction models. A fine balance between the large adsorbate−adsorbate dispersive forces, adsorbate−surface dispersive forces, gold ligation energy, and surface mining energy is shown to dictate the observed phenomena, leading to high surface mobility and substrate/surface lattice incommensurability. Increasing the magnitude of the dispersive forces through use of DPPZ, rather than PHEN, to disturb this balance produced physisorbed monolayers without pits and/or surface registration but with much longer-range order. Analogies are drawn with similar but poorly understood processes involved in the binding of thiols to Au(111).

Phosphorus-carbon nanocomposite anodes for lithium-ion and sodium-ion batteries

With the expected theoretical capacity of 2596 mA h g-1, phosphorus is considered to be the highest capacity anode material for sodium-ion batteries and one of the most attractive anode materials for lithium-ion systems. This work presents a comprehensive study of phosphorus-carbon nanocomposite anodes for both lithium-ion and sodium-ion batteries. The composite electrodes are able to display high initial capacities of approximately 1700 and 1300 mA h g-1 in lithium and sodium half-cells, respectively, when the cells are tested within a larger potential windows of 2.0-0.01 V vs. Li/Li+ and Na/Na+. The level of demonstrated capacity is underpinned by the storage mechanism, based on the transformation of phosphorus to Li3P phase for lithium cells and an incomplete transformation to Na3P phase for sodium cells. The capacity deteriorates upon cycling, which is shown to originate from disintegration of electrodes and their delamination from current collectors by post-cycling ex situ electron microscopy. Stable cyclic performance at the level of ∼700 and ∼350-400 mA h g-1 can be achieved if the potential windows are restricted to 2.0-0.67 V vs. Li/Li+ for lithium and 2-0.33 vs. Na/Na+ for sodium half-cells. The results are critically discussed in light of existing literature reports

Understanding structure-function relationship in hybrid Co3O4-Fe2O3/C lithium-ion battery electrodes

A range of high-capacity Li-ion anode materials (conversion reactions with lithium) suffer from poor cycling stability and limited high-rate performance. These issues can be addressed through hybridization of multiple nanostructured components in an electrode. Using a Co3O4-Fe2O3/C system as an example, we demonstrate that the cycling stability and rate performance are improved in a hybrid electrode. The hybrid Co3O4-Fe2O3/C electrode exhibits long-term cycling stability (300 cycles) at a moderate current rate with a retained capacity of approximately 700 mAh g(-1). The reversible capacity of the Co3O4-Fe2O3/C electrode is still about 400 mAh g(-1) (above the theoretical capacity of graphite) at a high current rate of ca. 3 A g(-1), whereas Co3O4-Fe2O3, Fe2O3/C, and Co3O4/C electrodes (used as controls) are unable to operate as effectively under identical testing conditions. To understand the structure-function relationship in the hybrid electrode and the reasons for the enhanced cycling stability, we employed a combination of ex situ and in situ techniques. Our results indicate that the improvements in the hybrid electrode originate from the combination of sequential electrochemical activity of the transition metal oxides with an enhanced electronic conductivity provided by percolating carbon chains.

Electrochemical impedance spectroscopy as a tool to measure cathodic disbondment on coated steel surfaces: capabilities and limitations

The disbondment of protective organic coatings under excessive cathodic protection potentials is a widely reported coating failure mechanism. Traditional methods of evaluating cathodic disbondment are based on ex situ visual inspection of coated metal surfaces after being exposed to standard cathodic disbondment testing conditions for a long period of time. Although electrochemical impedance spectroscopy (EIS) has been employed as an effective means of evaluating various anti-corrosion properties of organic coatings; its application for assessing the cathodic disbondment resistance of coatings has not been sufficiently exploited. This paper reports an experimental study aimed at developing EIS into a tool for in situ measurement and monitoring of cathodic disbondment of coatings. A clear correlation between EIS parameters and the disbonded coating areas has been confirmed upon short term exposure of epoxy-coated steel electrodes to cathodic disbondment conditions; however the degree of this correlation was found to decrease with the extension of exposure duration. This observation suggests that EIS loses its sensitivity with the propagation of coating disbondment, and that in order to achieve quantitative determination of the coating cathodic disbondment localized EIS measurements are required to measure the parameters related to local disbonded areas.

Use of optical interferometry to measure gold nanoparticle adsorption on silica

Adsorption of metal nanoparticles is at the heart of many chemical and biosensor techniques, but there are few approaches that can provide quantitative characterisation of individual nanoparticle films fabricated at different times and/or under different conditions. Using synthesised gold nanoparticles (Au NPs) as a model, the nanoparticle films were investigated using an optical interferometry technique known as fringes of equal chromatic order (FECO), which was further systematically validated against both in situ quartz crystal microbalance (QCM) and ex situ atomic force microscopy (AFM) measurements. The results indicate that the FECO wavelengths has a quantifiable red shift with increasing particle densities, making it possible to quantify the degree of surface coverage via the analysis of the fringe shift at a fixed fringe order. Moreover, the calculated formula between the FECO shifts and the surface coverage allows quantitative analysis of the whole adsorption kinetics investigated. Particularly, the as-proposed FECO technique can successfully monitor the Au NP adsorption in situ, which could be a new versatile technology platform for “online” monitoring method, for example in biosensor applications using Au NP-tagged analytes.

On-site determination of Pb2+ and Cd2+ in seawater by double stripping voltammetry with bismuth-modified working electrodes

To meet the urgent requirement of determining trace Pb2+ and Cd2+ in seawater on site, herein we developed a simple but novel electrochemical method, named as double stripping voltammetry, using only a portable heavy metal analyzer. The proposed method consisted of three steps: First, the targeted heavy metal ions in bulk solution were concentrated onto an ionic liquid-graphite-based paste working electrode (ILGPE), which exhibits a dramatic ability of accumulation, by electrodeposition in the presence of Bi3+. Second, the three-electrode arrangement, including the ILGPE loaded with the reduced products, was transferred into 1.0mL acetate buffer solution, followed by a stripping procedure. Third, the measurement was performed with the other stripping voltammetry procedure by using a glassy carbon electrode as working electrode. Under optimum conditions, the linear range values for Pb2+ and Cd2+ in seawater were 0.2-3.2 μg/L and 0.1-3.2 μg/L, respectively. The concentrations of Pb2+ and Cd2+ in five real samples collected from coastal sites of Qingdao City were determined on site, and the results were in good agreement with that obtained with the atomic absorption spectroscopy method. In addition, the analytical performance of working electrode modified with Bi film by in situ mode was investigated in comparison with that by ex situ mode. The results showed that the in situ mode was much better than the ex situ one.

The importance and significance of heritage conservation of ex-tin mining landscape in Perak, the Abode of Grace

The thematic history of tin mining in Perak reveals the evolution of tin production, technology, infrastructure, transportation, social and the state economic development. The mining expansion that spread from Larut district to Kinta at the end of nineteenth century has distinctively impact on it's landscape. The surviving evidences that spread over Kinta demonstrates the importance and significance of conservation of ex-tin mining places. These surviving evidences are testimony of the past history and legacy for the present and future generations.

A review of the conservation ecology of round-leaf Pomaderris Pomaderris vacciniifolia F. Muell. ex Reissek (Rhamnaceae)

Round-leaf Pomaderris Pomaderris vacciniifolia F. Muell. ex Reissek (Rhamnaceae) is a Victorian endemic shrub listed as threatened under the Flora and Fauna Guarantee Act 1988 and critically endangeredunder the Environment Protection and Biodiversity Conservation Act 1999. A review of the available literature for P. vacciniifolia indicated most information is anecdotal or found in unpublished works. Better understanding of the ecology of P. vacciniifolia may help explain why it is vulnerable, and enhance future management. Future research should focus towards better understanding of P. vacciniifolia habitat, reproductive ecology, seed dispersal mechanisms and competitive ability and how these compare with more common sympatric congeners, to determine whether any differences could explain the relative success of these species. Targeted searches for this species on public and private land are warranted to reveal additional populations and fully appreciate the distribution of this species. (The Victorian Naturalist 131 (2) 2014, 44-51).