Geochemical and isotopic composition of Bransfield Basin Lavas collected during SONNE cruise SO155

Bransfield Basin is an actively extending marginal basin separating the inactive South Shetland arc from the northern Antarctic Peninsula. Rift-related volcanism is widespread throughout the central Bransfield Basin, but the wider eastern Bransfield Basin was previously unsampled. Lavas recovered from the eastern subbasin form three distinct groups: (1) Bransfield Group has moderate large-ion lithophile element (LILE) enrichment relative to normal mid-ocean ridge basalt (NMORB), (2) Gibbs Group has strong LILE enrichment and is restricted to a relic seamount interpreted as part of the South Shetland arc, and (3) fresh alkali basalt was recovered from the NE part of the basin near Spanish Rise. The subduction-related component in Bransfield and Gibbs Group lavas is a LILE-rich fluid with radiogenic Sr, Nd, and Pb isotope compositions derived predominantly from subducting sediment. These lavas can be modeled as melts from Pacific MORB source mantle contaminated by up to 5% of the subduction-related component. They further reveal that Pacific mantle, rather than South Atlantic mantle, has underlain Bransfield Basin since 3 Ma. Magma productivity decreases abruptly east of Bridgeman Rise, and lavas with the least subduction component outcrop at that end. Both the eastward decrease in subduction component and occurrence of young alkali basalts require that subduction-modified mantle generated during the lifetime of the South Shetland arc has been progressively removed from NE to SW. This is inconsistent with previous models suggesting continued slow subduction at the South Shetland Trench but instead favors models in which the South Scotia Ridge fault has propagated westward since 3 Ma generating transtension across the basin.

Sedimentology on cores off Filchner Shelf Ice, Weddell Sea, Antarctica

The sediments of 14 box cores and 7 gravity cores, mainly taken directly in front of the Filchner(-Ronne) ice shelf northwest of Berkner Island (Weddell Sea), allowed to distinguish six sediment types. On the one hand,the retreat of the at first grounded and then floated ice from the last glacial maximum is documented. On the other hand,the sediments give an insight into extensive Holocene sediment deposition and remobilization northwest of Berkner Island. The ortho till was deposited directly by the grounded ice sheet and is lacking any marine influence. After floating of the ice shelf, partly very weIl stratified, partly unstratified, non-bioturbated paratill is deposited beneath the ice shelf. Lack of IRD-content in the paratill immediately above the orthotill indicates freezing at the bottom of the ice, at least for a short period after the ice became afloat. The orthotill and paratill contain small amounts of fragmented Tertiary diatoms, which allow the conclusion, that glacial-marine sediments in the accumulation area of the Ronne ice shelf will be eroded and later deposited by ice in the investigation area. Starting of bioturbation and therefore change in sedimentation from paratill to bioturbated paratill,is caused by the retreat of the ice shelf to its actual position. Isostatic uplift of the sea-bed after the Ice Age causes minor water depths with higher current velocities. The fine-fraction is eroding and mean particle-size will increase. Maybe, also isostatic uplift is responsible for repeated great advances of the floated ice shelf as shown in an erosional horizon in some cores containing bioturbated paratill. Postglacial sediment-thicknesses exceed 3 m. Assuming floating of the ice 15.000 YBP, accumulation rates reach nearly 20cm/lOOO years. Following the theories about sediment input in front of wide ice shelves, this was not expected. In the shallower water depths of Berkner Bank, the oscillations of the ice shelf are recorded in the sediments. Sorting and redistribution by high current velocities from beneath the ice up to the calving line, lead to the deposition of the weIl to very weIl sorted sandy till. In front of the calving line the finer fraction will settle down. Remobilization is possible by bioturbation and increasing current-velocity. According to the intensity of mixing of the sandy till with the fine fraction, modified till or muddy till results.

Lasting mantle scars lead to perennial plate tectonics

R.N.P. and P.J.H. are grateful for funding from an NSERC Discovery Grant. Computations were performed on the GPC supercomputer at the SciNet HPC Consortium. SciNet is funded by the Canada Foundation for Innovation under the auspices of Compute Canada, the Government of Ontario, Ontario Research Fund—Research Excellence and the University of Toronto. Numerical calculations were done using a modified version of the SOPALE (2000) software. The SOPALE modelling code was originally developed by Philippe Fullsack at Dalhousie University with Chris Beaumont and his Geodynamics group.

Direct In Vivo Manipulation and Imaging of Calcium Transients in Neutrophils Identify a Critical Role for Leading-Edge Calcium Flux.

Calcium signaling has long been associated with key events of immunity, including chemotaxis, phagocytosis, and activation. However, imaging and manipulation of calcium flux in motile immune cells in live animals remain challenging. Using light-sheet microscopy for in vivo calcium imaging in zebrafish, we observe characteristic patterns of calcium flux triggered by distinct events, including phagocytosis of pathogenic bacteria and migration of neutrophils toward inflammatory stimuli. In contrast to findings from ex vivo studies, we observe enriched calcium influx at the leading edge of migrating neutrophils. To directly manipulate calcium dynamics in vivo, we have developed transgenic lines with cell-specific expression of the mammalian TRPV1 channel, enabling ligand-gated, reversible, and spatiotemporal control of calcium influx. We find that controlled calcium influx can function to help define the neutrophil's leading edge. Cell-specific TRPV1 expression may have broad utility for precise control of calcium dynamics in other immune cell types and organisms.

An assessment of the influence of the industry distribution chain on the oxygen levels in commercial modified atmosphere packaged cheddar cheese using non-destructive oxygen sensor technology

The establishment and control of oxygen levels in packs of oxygen-sensitive food products such as cheese is imperative in order to maintain product quality over a determined shelf life. Oxygen sensors quantify oxygen concentrations within packaging using a reversible optical measurement process, and this non-destructive nature ensures the entire supply chain can be monitored and can assist in pinpointing negative issues pertaining to product packaging. This study was carried out in a commercial cheese packaging plant and involved the insertion of 768 sensors into 384 flow-wrapped cheese packs (two sensors per pack) that were flushed with 100% carbon dioxide prior to sealing. The cheese blocks were randomly assigned to two different storage groups to assess the effects of package quality, packaging process efficiency, and handling and distribution on package containment. Results demonstrated that oxygen levels increased in both experimental groups examined over the 30-day assessment period. The group subjected to a simulated industrial distribution route and handling procedures of commercial retailed cheese exhibited the highest level of oxygen detected on every day examined and experienced the highest rate of package failure. The study concluded that fluctuating storage conditions, product movement associated with distribution activities, and the possible presence of cheese-derived contaminants such as calcium lactate crystals were chief contributors to package failure.

(Table 2, page 10) Bulk spectroscopic, X-ray fluorescence and colorimetric analyses of samples from the San Pablo ferro-manganese pavement

The Bedford Institute of Oceanography provided ship time on the C.S.S. Hudson during the B.I.0. 1967 Metrology and IODAL Cruise for surveying two separate bottom features in the North Atlantic; the Flemish Cap and the San Pablo Seamount one of the Kelvin Seamounts (also known as the New England Seamounts) about 400 miles SSE of Halifax, Nova Scotia. Underwater photography, dredging, and drilling showed San Pablo seamount to have a very considerable covering of manganese deposit, which may be recoverable by mining. San Pablo Seamount was surveyed and sampled; good hauls were made both on the top and on the slopes, at various depths from 500-1000 fathoms; in all cases samples of an unusual stratified manganese-iron ore were recovered. In the hope of gaining additional information in the immediate sample area, one of the dredges had been previously modified to accommodate underwater photographic equipment. X-ray chemical analyses indicate that the ore contains 20 to 25 per cent MnO2, with similar amounts of Fe2O3. Since bottom photographs indicate that these deposits form a continuous cover 1 foot to 3 feet thick over most of the seamount, it is estimated that there are ore reserves in the order of 10 to 30 M tons above 1,000 fathoms.

Optimization of wastepaper sludge ash (WSA) in robust cementitious systems

Abstract : Wastepaper sludge ash (WSA) is generated by a cogeneration station by burning wastepaper sludge. It mainly consists of amorphous aluminosilicate phase, anhydrite, gehlenite, calcite, lime, C2S, C3A, quartz, anorthite, traces of mayenite. Because of its free lime content (~10%), WSA suspension has a high pH (13). Previous researchers have found that the WSA composition has poor robustness and the variations lead to some unsoundness for Portland cement (PC) blended WSA concrete. This thesis focused on the use of WSA in different types of concrete mixes to avoid the deleterious effect of the expansion due to the WSA hydration. As a result, WSA were used in making alkali-activated materials (AAMs) as a precursor source and as a potential activator in consideration of its amorphous content and the high alkaline nature. Moreover, the autogenous shrinkage behavior of PC concrete at low w/b ratio was used in order to compensate the expansion effect due to WSA. The concrete properties as well as the volume change were investigated for the modified WSA blended concrete. The reaction mechanism and microstructure of newly formed binder were evaluated by X-ray diffraction (XRD), calorimetry, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). When WSA was used as precursor, the results showed incompatible reaction between WSA and alkaline solution. The mixtures were not workable and provided very low compressive strength no matter what kinds of chemical activators were used. This was due to the metallic aluminum in WSA, which releases abundant hydrogen gas when WSA reacts with strong alkaline solution. Besides, the results of this thesis showed that WSA can activate the glassy phase contained in slag, glass powder (GP) and class F fly ash (FFA) with an optimum blended ratio of 50:50. The WSA/slag (mass ratio of 50:50) mortar (w/b of 0.47) attained 46 MPa at 28 days without heat curing assistance. A significant fast setting was noticed for the WSA-activated binder due to the C3A phase, free lime and metallic aluminum contained in the WSA. Adding 5% of gypsum can delay the fast setting, but this greatly increased the potential risk of intern sulfate attack. The XRD, TGA and calorimetry analyses demonstrated the formation of ettringite, C-S-H, portlandite, hydrogarnet and calcium carboaluminate in the hydrated binder. The mechanical performance of different binder was closely related to the microstructure of corresponding binder which was proved by the SEM observation. The hydrated WSA/slag and WSA/FFA binder formed a C-A-S-H type of gel with lower Ca/Si ratio (0.47~1.6). A hybrid gel (i.e. C-N-A-S-H) was observed for the WSA/GP binder with a very low Ca/Si ratio (0.26) and Na/Si ratio (0.03). The SEM/EDX analyses displayed the formation of expansive gel (ettringite and thaumasite) in the gypsum added WSA/slag concrete. The gradual emission of hydrogen gas due to the reaction of WSA with alkaline environment significantly increased the porosity and degraded the microstructure of hydrated matrix after the setting. In the last phase of this research WSA-PC blended binder was tailored to form a high autogenous shrinkage concrete in order to compensate the initial expansion. Different binders were proportioned with PC, WSA, silica fume or slag. The microstructure and mechanical properties of concrete can be improved by decreasing w/b ratios and by incorporating silica fume or slag. The 28-day compressive strength of WSA-blended concrete was above 22 MPa and reached 45 MPa when silica fume was added. The PC concrete incorporating silica fume or slag tended to develop higher autogenous shrinkage at low w/b ratios, and thus the ternary binder with the addition of WSA inhibited the long term shrinkage due to the initial expansion property to WSA. In the restrained shrinkage test, the concrete ring incorporating the ternary binder (PC/WSA/slag) revealed negligible potential to cracking up to 96 days as a result of the offset effect by WSA expansion. The WSA blended regular concrete could be produced for potential applications with reduced expansion, good mechanical property and lower permeability.

Progesterone analogue protects stressed photoreceptors via bFGF-mediated calcium influx.

Retinitis pigmentosa (RP) is a degenerative retinal disease leading to photoreceptor cell loss. In 2011, our group identified the synthetic progesterone ‘Norgestrel’ as a potential treatment for RP. Subsequent research showed Norgestrel to work through progesterone receptor membrane component 1 (PGRMC1) activation and upregulation of neuroprotective basic fibroblast growth factor (bFGF). Using trophic factor deprivation of 661W photoreceptor-like cells, we aimed to further elucidate the mechanism leading to Norgestrel-induced neuroprotection. In the present manuscript, we show by flow cytometry and live-cell immunofluorescence that Norgestrel induces an increase in cytosolic calcium in both healthy and stressed 661Ws over 24h. Specific PGRMC1 inhibition by AG205 (1 μM) showed this rise to be PGRMC1-dependent, primarily utilising calcium from extracellular sources, for blockade of L-type calcium channels by verapamil (50 μM) prevented a Norgestrel-induced calcium influx in stressed cells. Calcium influx was also shown to be bFGF-dependent, for siRNA knock down of bFGF prevented Norgestrel-PGRMC1 induced changes in cytosolic calcium. Notably, we demonstrate PGRMC1-activation is necessary for Norgestrel-induced bFGF upregulation. We propose that Norgestrel protects through the following pathway: binding to and activating PGRMC1 expressed on the surface of photoreceptor cells, PGRMC1 activation drives bFGF upregulation and subsequent calcium influx. Importantly, raised intracellular calcium is critical to Norgestrel's protective efficacy, for extracellular calcium chelation by EGTA abrogates the protective effects of Norgestrel on stressed 661W cells in vitro.

The effect of ionic Co presence on the structural, optical and photocatalytic properties of modified cobalt–titanate nanotubes

With the aim of producing materials with enhanced optical and photocatalytic properties, titanate nanotubes (TNTs) modified by cobalt doping (Co-TNT) and by Na+ -> Co ion-exchange (TNT/Co) were successfully prepared by a hydrothermal method. The influence of the doping level and of the cobalt position in the TNT crystalline structure was studied. Although no perceptible influence of the cobalt ion position on the morphology of the prepared titanate nanotubes was observed, the optical behaviour of the cobalt modified samples is clearly dependent on the cobalt ions either substituting the Ti4+ ions in the TiO6 octahedra building blocks of the TNT structure (doped samples) or replacing the Na+ ions between the TiO6 interlayers (ion-exchange samples). The catalytic ability of these materials on pollutant photodegradation was investigated. First, the evaluation of hydroxyl radical formation using the terephthalic acid as a probe was performed. Afterwards, phenol, naphthol yellow S and brilliant green were used as model pollutants. Anticipating real world situations, photocatalytic experiments were performed using solutions combining these pollutants. The results show that the Co modified TNT materials (Co-TNT and TNT/Co) are good catalysts, the photocatalytic performance being dependent on the Co/Ti ratio and on the structural metal location. The Co(1%)-TNT doped sample was the best photocatalyst for all the degradation processes studied.

Functional alkali tantalate 2D structures for microelectronics and related applications

Alkali tantalates and niobates, including K(Ta / Nb)O3, Li(Ta / Nb)O3 and Na(Ta / Nb)O3, are a very promising ferroic family of lead-free compounds with perovskite-like structures. Their versatile properties make them potentially interesting for current and future application in microelectronics, photocatalysis, energy and biomedics. Among them potassium tantalate, KTaO3 (KTO), has been raising interest as an alternative for the well-known strontium titanate, SrTiO3 (STO). KTO is a perovskite oxide with a quantum paraelectric behaviour when electrically stimulated and a highly polarizable lattice, giving opportunity to tailor its properties via external or internal stimuli. However problems related with the fabrication of either bulk or 2D nanostructures makes KTO not yet a viable alternative to STO. Within this context and to contribute scientifically to the leverage tantalate based compounds applications, the main goals of this thesis are: i) to produce and characterise thin films of alkali tantalates by chemical solution deposition on rigid Si based substrates, at reduced temperatures to be compatible with Si technology, ii) to fulfil scientific knowledge gaps in these relevant functional materials related to their energetics and ii) to exploit alternative applications for alkali tantalates, as photocatalysis. In what concerns the synthesis attention was given to the understanding of the phase formation in potassium tantalate synthesized via distinct routes, to control the crystallization of desired perovskite structure and to avoid low temperature pyrochlore or K-deficient phases. The phase formation process in alkali tantalates is far from being deeply analysed, as in the case of Pb-containing perovskites, therefore the work was initially focused on the process-phase relationship to identify the driving forces responsible to regulate the synthesis. Comparison of phase formation paths in conventional solid-state reaction and sol-gel method was conducted. The structural analyses revealed that intermediate pyrochlore K2Ta2O6 structure is not formed at any stage of the reaction using conventional solid-state reaction. On the other hand in the solution based processes, as alkoxide-based route, the crystallization of the perovskite occurs through the intermediate pyrochlore phase; at low temperatures pyrochlore is dominant and it is transformed to perovskite at >800 °C. The kinetic analysis carried out by using Johnson-MehlAvrami-Kolmogorow model and quantitative X-ray diffraction (XRD) demonstrated that in sol-gel derived powders the crystallization occurs in two stages: i) at early stage of the reaction dominated by primary nucleation, the mechanism is phase-boundary controlled, and ii) at the second stage the low value of Avrami exponent, n ~ 0.3, does not follow any reported category, thus not permitting an easy identification of the mechanism. Then, in collaboration with Prof. Alexandra Navrotsky group from the University of California at Davis (USA), thermodynamic studies were conducted, using high temperature oxide melt solution calorimetry. The enthalpies of formation of three structures: pyrochlore, perovskite and tetragonal tungsten bronze K6Ta10.8O30 (TTB) were calculated. The enthalpies of formation from corresponding oxides, ∆Hfox, for KTaO3, KTa2.2O6 and K6Ta10.8O30 are -203.63 ± 2.84 kJ/mol, - 358.02 ± 3.74 kJ/mol, and -1252.34 ± 10.10 kJ/mol, respectively, whereas from elements, ∆Hfel, for KTaO3, KTa2.2O6 and K6Ta10.8O30 are -1408.96 ± 3.73 kJ/mol, -2790.82 ± 6.06 kJ/mol, and -13393.04 ± 31.15 kJ/mol, respectively. The possible decomposition reactions of K-deficient KTa2.2O6 pyrochlore to KTaO3 perovskite and Ta2O5 (reaction 1) or to TTB K6Ta10.8O30 and Ta2O5 (reaction 2) were proposed, and the enthalpies were calculated to be 308.79 ± 4.41 kJ/mol and 895.79 ± 8.64 kJ/mol for reaction 1 and reaction 2, respectively. The reactions are strongly endothermic, indicating that these decompositions are energetically unfavourable, since it is unlikely that any entropy term could override such a large positive enthalpy. The energetic studies prove that pyrochlore is energetically more stable phase than perovskite at low temperature. Thus, the local order of the amorphous precipitates drives the crystallization into the most favourable structure that is the pyrochlore one with similar local organization; the distance between nearest neighbours in the amorphous or short-range ordered phase is very close to that in pyrochlore. Taking into account the stoichiometric deviation in KTO system, the selection of the most appropriate fabrication / deposition technique in thin films technology is a key issue, especially concerning complex ferroelectric oxides. Chemical solution deposition has been widely reported as a processing method to growth KTO thin films, but classical alkoxide route allows to crystallize perovskite phase at temperatures >800 °C, while the temperature endurance of platinized Si wafers is ~700 °C. Therefore, alternative diol-based routes, with distinct potassium carboxylate precursors, was developed aiming to stabilize the precursor solution, to avoid using toxic solvents and to decrease the crystallization temperature of the perovskite phase. Studies on powders revealed that in the case of KTOac (solution based on potassium acetate), a mixture of perovskite and pyrochlore phases is detected at temperature as low as 450 °C, and gradual transformation into monophasic perovskite structure occurs as temperature increases up to 750 °C, however the desired monophasic KTaO3 perovskite phase is not achieved. In the case of KTOacac (solution with potassium acetylacetonate), a broad peak is detected at temperatures <650 °C, characteristic of amorphous structures, while at higher temperatures diffraction lines from pyrochlore and perovskite phases are visible and a monophasic perovskite KTaO3 is formed at >700 °C. Infrared analysis indicated that the differences are due to a strong deformation of the carbonate-based structures upon heating. A series of thin films of alkali tantalates were spin-coated onto Si-based substrates using diol-based routes. Interestingly, monophasic perovskite KTaO3 films deposited using KTOacac solution were obtained at temperature as low as 650 °C; films were annealed in rapid thermal furnace in oxygen atmosphere for 5 min with heating rate 30 °C/sec. Other compositions of the tantalum based system as LiTaO3 (LTO) and NaTaO3 (NTO), were successfully derived as well, onto Si substrates at 650 °C as well. The ferroelectric character of LTO at room temperature was proved. Some of dielectric properties of KTO could not be measured in parallel capacitor configuration due to either substrate-film or filmelectrode interfaces. Thus, further studies have to be conducted to overcome this issue. Application-oriented studies have also been conducted; two case studies: i) photocatalytic activity of alkali tantalates and niobates for decomposition of pollutant, and ii) bioactivity of alkali tantalate ferroelectric films as functional coatings for bone regeneration. Much attention has been recently paid to develop new type of photocatalytic materials, and tantalum and niobium oxide based compositions have demonstrated to be active photocatalysts for water splitting due to high potential of the conduction bands. Thus, various powders of alkali tantalates and niobates families were tested as catalysts for methylene blue degradation. Results showed promising activities for some of the tested compounds, and KNbO3 is the most active among them, reaching over 50 % degradation of the dye after 7 h under UVA exposure. However further modifications of powders can improve the performance. In the context of bone regeneration, it is important to have platforms that with appropriate stimuli can support the attachment and direct the growth, proliferation and differentiation of the cells. In lieu of this here we exploited an alternative strategy for bone implants or repairs, based on charged mediating signals for bone regeneration. This strategy includes coating metallic 316L-type stainless steel (316L-SST) substrates with charged, functionalized via electrical charging or UV-light irradiation, ferroelectric LiTaO3 layers. It was demonstrated that the formation of surface calcium phosphates and protein adsorption is considerably enhanced for 316L-SST functionalized ferroelectric coatings. Our approach can be viewed as a set of guidelines for the development of platforms electrically functionalized that can stimulate tissue regeneration promoting direct integration of the implant in the host tissue by bone ingrowth and, hence contributing ultimately to reduce implant failure.

Receptors, sparks and waves in a fire-diffuse-fire framework for calcium release

Calcium ions are an important second messenger in living cells. Indeed calcium signals in the form of waves have been the subject of much recent experimental interest. It is now well established that these waves are composed of elementary stochastic release events (calcium puffs or sparks) from spatially localised calcium stores. The aim of this paper is to analyse how the stochastic nature of individual receptors within these stores combines to create stochastic behaviour on long timescales that may ultimately lead to waves of activity in a spatially extended cell model. Techniques from asymptotic analysis and stochastic phase-plane analysis are used to show that a large cluster of receptor channels leads to a release probability with a sigmoidal dependence on calcium density. This release probability is incorporated into a computationally inexpensive model of calcium release based upon a stochastic generalization of the Fire-Diffuse-Fire (FDF) threshold model. Numerical simulations of the model in one and two dimensions (with stores arranged on both regular and disordered lattices) illustrate that stochastic calcium release leads to the spontaneous production of calcium sparks that may merge to form saltatory waves. Illustrations of spreading circular waves, spirals and more irregular waves are presented. Furthermore, receptor noise is shown to generate a form of array enhanced coherence resonance whereby all calcium stores release periodically and simultaneously.

I. Quantal effects in biochemical cooperativity and a proposed mechanism for the differentiation of calcium signaling in synaptic plasticity. II. Evolutionary algorithms for the optimization of methods in computational chemistry

In Part 1 of this thesis, we propose that biochemical cooperativity is a fundamentally non-ideal process. We show quantal effects underlying biochemical cooperativity and highlight apparent ergodic breaking at small volumes. The apparent ergodic breaking manifests itself in a divergence of deterministic and stochastic models. We further predict that this divergence of deterministic and stochastic results is a failure of the deterministic methods rather than an issue of stochastic simulations.

Ergodic breaking at small volumes may allow these molecular complexes to function as switches to a greater degree than has previously been shown. We propose that this ergodic breaking is a phenomenon that the synapse might exploit to differentiate Ca$^{2+}$ signaling that would lead to either the strengthening or weakening of a synapse. Techniques such as lattice-based statistics and rule-based modeling are tools that allow us to directly confront this non-ideality. A natural next step to understanding the chemical physics that underlies these processes is to consider \textit{in silico} specifically atomistic simulation methods that might augment our modeling efforts.

In the second part of this thesis, we use evolutionary algorithms to optimize \textit{in silico} methods that might be used to describe biochemical processes at the subcellular and molecular levels. While we have applied evolutionary algorithms to several methods, this thesis will focus on the optimization of charge equilibration methods. Accurate charges are essential to understanding the electrostatic interactions that are involved in ligand binding, as frequently discussed in the first part of this thesis.