New constraints on granulite facies metamorphism and melt production in the Lewisian Complex, northwest Scotland

In this study, we investigate the metamorphic history of the Assynt and Gruinard blocks of the Archean Lewisian Complex, northwest Scotland, which are considered by some to represent discrete crustal terranes. For samples of mafic and intermediate rocks, phase diagrams were constructed in the Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O2(NCKFMASHTO) system using whole-rock compositions. Our results indicate that all samples equilibrated at similar peak metamorphic conditions of ~8–10 kbar and ~900–1,000°C, consistent with field evidence for in situ partial melting and the classic interpretation of the central region of the Lewisian Complex as representing a single crustal block. Melt-reintegration modelling was employed in order to estimate probable protolith compositions. Phase equilibria calculated for these modelled undepleted precursors match well with those determined for a subsolidus amphibolite from Gairloch in the southern region of the Lewisian Complex. Both subsolidus lithologies exhibit similar phase relations and potential melt fertility, with both expected to produce orthopyroxene-bearing hornblende granulites, with or without garnet, at the conditions inferred for the Badcallian metamorphic peak. For fully hydrated protoliths, prograde melting is predicted to first occur at ~620°C and ~9.5 kbar, with up to 45% partial melt predicted to form at peak conditions in a closed-system environment. Partial melts calculated for both compositions between 610 and 1,050°C are mostly trondhjemitic. Although the melt-reintegrated granulite is predicted to produce more potassic (granitic) melts at ~700–900°C, the modelled melts are consistent with the measured compositions of felsic sheets from the central region Lewisian Complex

The Dataring intelligent tide gauge system remote site

Dataring is a computer based Logging and processing system which can be interrogated remotely by any 300 baud full duplex modem and terminal to transmit back data from up to seven sensors

A computational study of order-disorder phenomena in Mg2TiO4 spinel (qandilite)

We have used a combination of classical and quantum-mechanical atomistic calculations, together with Monte Carlo simulations, to study order-disorder phenomena in the spinel mineral qandilite, Mg2TiO4. Using an interatomic potential model akin to those previously used for 2-3 spinels yielded a general increase in energy E as a function of inversion parameter x, and thus incorrectly predicted a normal-spinel ground state, whereas the E(x) behavior as modeled by density-functional theory exhibited a maximum at an intermediate degree of inversion and correctly predicted an inverse-spinel ground state. We therefore used the quantum-mechanical simulations to derive pair interaction parameters (for nearest-neighbor tetrahedral-tetrahedral, octahedral-octahedral, and tetrahedral-octahedral interactions) and chemical potential to use in Monte Carlo simulations of order-disorder in qandilite. The simulated cation distributions compared favorably with those obtained experimentally, although the long-range ordering transition to the tetragonal P4122 phase was not observed when using only nearest-neighbor interactions. However, this transition could be observed following the addition of two extra parameters to the model. The simulations were used to calculate the effect of short- and long-range cation order on the configurational entropy of qandilite as a function of temperature. The calculated entropy of the high-temperature cubic phase was in very good agreement with the experimental value recently determined, supporting the suggestion that there is considerable short-range order in qandilite

Metasomatism of the continental crust and its impact on surface uplift: Insights from reactive‐transport modelling

High-elevation, low-relief continental plateaus are major topographic features and profoundly influence atmospheric circulation, sediment transport and storage, and biodiversity. Although orogenic surface-uplift mechanisms for modern continental plateaus near known plate margins like Tibet are well-characterized, they cannot account for examples in intracontinental settings like the Colorado Plateau. In contrast to canonical plate-tectonic uplift mechanisms, broad-scale hydration-induced metasomatism of the lower crust has been suggested to reduce its density and increase its buoyancy sufficiently to contribute to isostatic uplift. However, the relationships between key petrophysical properties in these environments are not fully quantified, which limits application of this model. Here, we develop a series of petrological models that describe the petrological and topographic effects of fluid–rock interaction in non-deforming continental crust of varying composition. We apply an open-system petrological modelling framework that utilizes reactive-transport calculations to determine the spatial and temporal scales over which mineralogic transformations take place compared with the magnitude of infiltration of aqueous fluids derived from devolatilization of subducting oceanic lithosphere. The buoyancy effect of hydration-induced de-densification is most significant for metabasic lower crust, intermediate for metapelitic crust, and minimal for granodioritic crust. We apply these results to a case study of the ~2 km-high Colorado Plateau and demonstrate that under ideal conditions, hydration of its lower–middle crust by infiltrating aqueous fluids released by the Farallon slab during Cenozoic low-angle subduction could have uplifted the plateau surface by a maximum of ~1 km over 16 Myr. However, realistically, although hydration likely has a measurable effect on surface tectonics, the uplift of orogenic plateaus is likely dominantly controlled by other factors, such as lithospheric delamination

Environmentally Sustainable Solvent-based Process Chemistry for Metals in Printed Circuit Boards

This chapter describes the development of several new processes relating to the fabrication, characterisation and recycling of printed circuit board (PCB) metal assemblies in alternative, sustainable solvent technologies based on an emergent class of liquids know as deep eutectic solvents (DES). It has been demonstrated that in many cases, the use of DES technologies can be disruptive to current process thinking and in principle can deliver benefits including increased efficiency,lower costs and better process control. These technologies offer the opportunity to incorporate new ideas into PCB fabrication and assembly that facilitate downstream, end-of-life recovery and separation consistent with a circular economy model. Current PCB manufacturing is carried out using many complex metal deposition processes involving aqueous solutions of toxic metal salts, strong inorganic acids, precious and expensive noble metals, and requires careful process control and monitoring. As a result, these processes are often costly to operate and inefficient. DES-based technologies can: (1) improve the economic and efficient use of essential metals; (2) reduce or eliminate use of precious and expensive metals; (3) reduce the use of complex and difficult to maintain process chemistry; (4) reduce reliance on toxic and noxious materials; and (5) improve recovery, recycling and reuse of PCB metals

Minimally invasive management of vital teeth requiring root canal therapy

The present study aimed to investigate the possible use of a non-instrumentation technique including blue light irradiation for root canal cleaning. Extracted human single rooted teeth were selected. Nine different groups included distilled water, NaOCl, intra-canal heated NaOCl, and NaOCl + EDTA irrigation after either instrumentation or non-instrumentation, and a laser application group following non-instrumentation technique. The chemical assessment of the root canal dentine was evaluated using EDS and FT-IR. Surface microstructural analyses were performed by using SEM. The antimicrobial efficacy of different preparation techniques was evaluated using microbial tests. Laser application didn’t change the Ca/P, carbonate/phosphate and amide I/phosphate ratios of the root canal dentin the root canal dentin preserved its original form after light application. The instrumentation decreased the carbonate/phosphate and amide I/phosphate ratios of the root canal dentin regardless of the irrigation solution or technique (p < 0.05). According to the microbiological tests, the light application could not provide antibacterial efficacy as much as NaOCl irrigation. The NaOCl irrigation both in the non-instrumentation and instrumentation groups significantly reduced the number of bacteria (p < 0,05). Minimally invasive root canal preparation techniques where the root canal is not instrumented and is disinfected by laser irradiation followed by obturation with a hydraulic cement sealer may be an attractive treatment option for management of vital teeth needing root canal therapy and does not have any detrimental effects on the chemical structure of dentin

Design and development of a new flowable and photocurable lactide and caprolactone-based polymer for bone repair and augmentation

With a global aging population, there is a high demand for new biomaterials that provide regenerative or fixation modalities following a bone injury. Here, the design and development of newly synthesised poly(l-lactic acid)-dimethacrylate (PLLA-DM) and poly(caprolactone-co-fumarate)-dimethacrylate (PCF-DM) monomer systems serves to address some of the main medical challenges and requirements of surgeons during application and better postoperative outcomes of new bone-healing biomaterials. Synthesis of PLLA-DM and PCF-DM via ring opening polymerisation (ROP) and polycondensation routes led to low MW ‘flowable’ and resorbable monomers that polymerise in-situ at up to 6 mm curing depth. Tensile testing of photocured PLLA-DM/PCF-DM formulations at strain rate 0.05 s−1, revealed elastic moduli of 4.4 ± 0.5 to 11.7 ± 2.5 (SD) GPa, with ultimate tensile strength ranging between 29.7 ± 4.9 to 76.1 ± 13.5 (SD) MPa. Resazurin-based metabolic activity studies via an indirect contact method involving Saos-2 osteoblast-like cell lines revealed enhanced cytocompatibility with metabolic activity of treated Saos-2 cells increasing by up to 20% compared with respective untreated control groups. Attachment of Saos-2 cells on PLLA-DM/PCF-DM specimen surfaces revealed cellular structures such as filopodia extending beyond lamellipodia, indicative of remarkable cell adhesion and favouring colonization. The initial development of the polymer chemistry presented here provides the potential for the design and further development towards a new resorbable biomaterial with enhanced mechanical properties for bone repair and augmentation involving both orthopaedic (bone cement) and restorative dentistry applications