Sodium Enrichment Research Articles

Desalination-Coupled (photo)Electrocatalysis for Production of Value-Added Chemicals

Water and energy are the most essential elements for a sustainable human society. They are strongly interdependent because energy production requires a significant amount of water, while the production, processing, distribution, and end-use of water requires large energy inputs. Several water-energy nexus technologies have emerged, including PV-electrolysis and microbial desalination. Herein, we propose a hybrid process that is driven by sunlight and boosted by electrodialysis. A sunlit inorganic photoanode initiates the desalination of saline water in the middle cell. As the chloride in the middle cell moves to the anode cell, the wastewater (WW) treatment is boosted by reactive chlorine species (RCS) generated via the reaction with photogenerated holes. An increase in the electrical conductivity in the anode cell further enhances the photoelectrocatalytic (PEC) WW treatment. Upon a potential bias, various value-added chemicals (H2 via water reduction, H2O2 via O2 reduction, and HCOOH via CO2 reduction) are produced in the cathode cell, and the production of the chemical is enhanced as the desalination proceeds because of sodium enrichment (i.e., conductivity increase). The uniqueness and advantages of this hybrid process include its broad range of operating conditions (virtually the entire pH range) and the wide variety of inorganic and organic substrates that can be treated (i.e., aquatic pollutants), while desalination boosts the overall operation and chloride catalyzes the anodic reaction, which in turn facilitates the desalination. Although tested as a proof-of-concept, the present technology opens up a novel field involving a sunlight-water-energy nexus, promising high efficiency desalination and the desalination-boosted remediation of water with simultaneous production of value-added chemicals.

Sodium chloride in the tumor microenvironment enhances T cell metabolic fitness and cytotoxicity

The efficacy of antitumor immunity is associated with the metabolic state of cytotoxic T cells, which is sensitive to the tumor microenvironment. Whether ionic signals affect adaptive antitumor immune responses is unclear. In the present study, we show that there is an enrichment of sodium in solid tumors from patients with breast cancer. Sodium chloride (NaCl) enhances the activation state and effector functions of human CD8+ T cells, which is associated with enhanced metabolic fitness. These NaCl-induced effects translate into increased tumor cell killing in vitro and in vivo. Mechanistically, NaCl-induced changes in CD8+ T cells are linked to sodium-induced upregulation of Na+/K+-ATPase activity, followed by membrane hyperpolarization, which magnifies the electromotive force for T cell receptor (TCR)-induced calcium influx and downstream TCR signaling. We therefore propose that NaCl is a positive regulator of acute antitumor immunity that might be modulated for ex vivo conditioning of therapeutic T cells, such as CAR T cells.

Pedipalp anatomy of the Australian black rock scorpion, Urodacus manicatus, with implications for functional morphology

Pedipalps – chelate ‘pincers’ as the second pair of prosomal appendages – are a striking feature of scorpions and are employed in varied biological functions. Despite the distinctive morphology and ecological importance of these appendages, their anatomy remains underexplored. To rectify this, we examined the pedipalps of the Australian black rock scorpion, Urodacus manicatus, using a multifaceted approach consisting of microcomputed tomography, scanning electron microscopy, energy dispersive X-ray spectroscopy, and live pinch force measurements. In doing so, we document the following aspects of the pedipalps: (1) the musculature in three dimensions; (2) the cuticular microstructure, focusing on the chelae (tibial and tarsal podomeres); (3) the elemental construction of the chelae teeth; and (4) the chelae pinch force. We recognise 25 muscle groups in U. manicatus pedipalps, substantially more than previously documented in scorpions. The cuticular microstructure – endo-, meso-, and exocuticle – of U. manicatus pedipalps is shown to be similar to other scorpions and that mesocuticle reinforces the chelae for predation and burrowing. Elemental mapping of the chelae teeth highlights enrichment in calcium, chlorine, nickel, phosphorus, potassium, sodium, vanadium, and zinc, with a marked lack of carbon. These elements reinforce the teeth, increasing robustness to better enable prey capture and incapacitation. Finally, the pinch force data demonstrate that U. manicatus can exert high pinch forces (4.1 N), further highlighting the application of chelae in subduing prey, as opposed to holding prey for envenomation. We demonstrate that U. manicatus has an array of adaptions for functioning as a sit-and-wait predator that primarily uses highly reinforced chelae to process prey.

Geophagy by a large herbivore (capybara, Hydrochoerus hydrochaeris) driven by a human sodium supply

AbstractReasons for geophagy (soil consumption) by herbivorous animals have long been debated. We provide direct evidence of artificial sodium (Na) enrichment driving geophagy by capybaras (Hydrochoerus hydrochaeris), a large herbivore in western Amazonia.Abstract in Spanish is available with online material.

Distribution, Occurrence and Enrichment Causes of Sodium in Middle Jurassic Coal from Zhundong Coalfield, Xinjiang

The coal found in the Zhundong Coalfield is highly suitable for power generation and gasification. However, the high sodium content within the coal leads to severe boiler slagging and contamination. Additionally, sodium disperses into the gaseous phase to form haze, adversely affecting the local atmospheric environment. This study delved into the distribution and occurrence characteristics and enrichment causes of sodium in the coal, employing sequential extraction experiments and testing methods such as XRF, ICP-OES and SEM-EDS. The findings of this research indicate the following: (1) With the increasing burial depth of coal seams, there is a noticeable decrease in the sodium content within the coal. Sodium is primarily distributed within the coal seam, with higher concentrations observed in the upper portions of the same coal seam. Furthermore, the distribution of sodium within the epipedon, overlying rocks and coal seam also exhibits a decreasing trend. (2) Sodium primarily exists in a water-soluble state within coal seams, with H2O-Na accounting for over 70% of its composition. The ion-exchangeable sodium is higher than that in the roof, floor and gangue. Sodium exists in coal seams in both ionic and hydrated ionic forms. It is worth noting that the minerals within coal are not the primary carriers of sodium. (3) These coal seams were formed in a warm and humid shallow lake peat swamp environment, which is not significantly influenced by terrestrial or marine sources. The enrichment of sodium is primarily influenced by later hydrodynamic conditions.

A multi-species reactive transport model based on gas-ion-solid phase interaction for the carbonation of cement-based materials

This study presents a reactive transport modelling framework for understanding carbonation processes through pore solution composition, phase assemblage changes in cement-based materials, and pore solution composition changes on steel corrosion. The study emphasizes the significance of considering pore structure changes on mass transport and utilizing a surface complexation model for predicting changes in pore solution composition and comprehending its influence on steel corrosion. A clear enrichment in sodium and potassium content in carbonated regions is observed upon carbonation, which leads to a decrease in alkali concentration in the pore solution, and alkali ions are transported toward the carbonated zone. Simultaneously, the opposite behaviour is observed for both the sulphur and chloride content. The increase in the concentration of sulphur and chloride in the pore solution was observed upon the decomposition of the solid phase. Calcium ions are transported to the carbonated zone, further increasing calcite formation near the exposed surface.

New constraints on sodium production in globular clusters from theNa23(He3,d)Mg24reaction

The star-to-star anticorrelation of sodium and oxygen is a defining feature of globular clusters, but, to date, the astrophysical site responsible for this unique chemical signature remains unknown. Sodium enrichment within these clusters depends sensitively on reaction rate of the sodium destroying reactions $^{23}\mathrm{Na}(p,\ensuremath{\gamma})$ and $^{23}\mathrm{Na}(p,\ensuremath{\alpha})$. In this paper, we report the results of a $^{23}\mathrm{Na}{(^{3}\mathrm{He},d)}^{24}\mathrm{Mg}$ transfer reaction carried out at Triangle Universities Nuclear Laboratory using a $21\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}\phantom{\rule{0.16em}{0ex}}^{3}\mathrm{He}$ beam. Astrophysically relevant states in $^{24}\mathrm{Mg}$ between $11<{E}_{x}<12\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ were studied using high-resolution magnetic spectroscopy, thereby allowing the extraction of excitation energies and spectroscopic factors. Bayesian methods are combined with the distorted wave Born approximation to assign statistically meaningful uncertainties to the extracted spectroscopic factors. For the first time, these uncertainties are propagated through to the estimation of proton partial widths. Our experimental data are used to calculate the reaction rate. The impact of the new rates are investigated using asymptotic giant branch star models. It is found that while the astrophysical conditions still dominate the total uncertainty, intramodel variations on sodium production from the $^{23}\mathrm{Na}(p,\ensuremath{\gamma})$ and $^{23}\mathrm{Na}(p,\ensuremath{\alpha})$ reaction channels are a lingering source of uncertainty.

High-temperature detoxification strategy based on thermal analysis kinetics for resource utilization of biopharmaceutical waste

High-temperature pyrolytic detoxification reactions based on thermal analysis facilitate the resource reuse of solid waste from the biopharmaceutical industry. This study described thermodynamic parameters, gas by-products, and safety assessment. The most common emissions (H2O, O, NH3) peak at 345–440 °C, accompanied by a shift in the micro-interfacial reaction mechanism, resulting in the largest rate of weight loss and the most significant release of gaseous by-products from the reaction. The peak CO2, SO2, and N2 emissions were dominated by deamination and sodium enrichment reactions, following the Mampel Power law mechanism. The growth trends of protein-nucleated Chlorella indicated the safety of the product at each stage. Compared to sample 375, sample 440 promoted the growth of Chlorella to a certain extent (maximum boost of 0.24 g⋅L-1⋅d-1), indicating non-toxicity and neutral pH, which may be due to a shift in pH to neutral as a result of pyrolytic detoxification, thus increasing safety and facilitating resource recovery. Possible reaction pathways for the pyrolysis of solid products were derived, and the availability of end products that contribute to the safe reuse of final value-added products from biopharmaceutical waste.

Determining the Mobility of some Essential Elements in Saffron (Crocus sativus L.) by the Neutron Activation Analysis

The main purpose of this investigation is to evaluate the concentrations of six essential metals (Na+, Mg2+, K+, Ca2+, Fe2+ and Zn2+) in saffron and a farm soil using the neutron activation analysis (NAA) as a nuclear spectrometry method. The stratified random sampling method was used here. The NAA results showed the well uptake of Mg2+, K+, Ca2+, Fe2+, and Zn2+ in saffron, which is lower than the toxicity range. Based on the contamination factor and geoaccumulation index, soil contamination levels were determined uncontaminated by Zn, moderately contaminated by Na+ and Fe2+, and strongly contaminated by Ca2+, K+, and Mg2+. Results of the contamination degree and pollution load index indicated moderately/strongly soil contamination and a moderate geometric mean of the contamination index. The Na+ enrichment factor (EF) showed a minimal man-made impact on sodium enrichment. Saffron cultivation has likely caused more accumulations of Mg2+, K+, Ca2+, and Fe2+, as well as a considerable deficiency of Zn2+ in the soil, based on EFs. The biological concentration factor showed a significant zinc accumulation by the corm of saffron. There was well translocation from corm to all the aerial tissues for K+. Also, sodium adsorption ratio, exchangeable sodium percentage, pH, and electrical conductivity evaluated the non-salinity level of soil in all saffron farms.

ToF-SIMS of femtosecond laser irradiated muscovite with topography: Evidence of Na and K enrichment near the surface

ToF-SIMS is a sensitive technique for interrogating chemical composition at or near the surface of a material, with an emphasis on detecting elements present in extremely low quantities. Here, it was utilized to determine changes in element distribution at a muscovite surface caused by a single 150 fs laser pulse at 800 nm. Muscovite is a mineral with the standard chemical formula KAl2 (Si3Al) O10(OH)2. As a natural mineral, the composition varies. Several ions were studied including aluminium (Al), potassium (K), sodium (Na), and silicon (Si). The laser-irradiated surface area is microscopic - a few microns in diameter. To achieve spatial resolution of the ions within the laser treated region, a ∼100 nm wide ion beam is used. The laser material interaction produces a non-flat surface morphology that changes as the laser pulse fluence increases. Thus, ToF-SIMS is influenced by the ion beam shadowing effect. After the implications of artefacts linked to this are taken into account, there is a finding of net enrichment of sodium and potassium due to the laser irradiation. ToF-SIMS also shows differences in the elemental makeup of nanoparticulates ejected from the laser treated region and redeposited on the surrounding surface. With careful consideration of surface morphological changes, this study shows that ToF-SIMS can be employed in laser materials processing studies to investigate changes in elemental distribution.

Skin sodium is increased in male patients with multiple sclerosis and related animal models

Novel MRI techniques allow a noninvasive quantification of tissue sodium and reveal the skin as a prominent compartment of sodium storage in health and disease. Since multiple sclerosis (MS) immunopathology is initiated in the periphery and increased sodium concentrations induce proinflammatory immune cells, the skin represents a promising compartment linking high sodium concentrations and MS immunopathology. We used a 7-T sodium MRI (23Na-MRI) and inductively coupled plasma mass spectrometry to investigate the skin sodium content in two mouse models of MS. We additionally performed 3-T 23Na-MRI of calf skin and muscles in 29 male relapsing-remitting MS (RRMS) patients and 29 matched healthy controls. Demographic and clinical information was collected from interviews, and disease activity was assessed by expanded disability status scale scoring. 23Na-MRI and chemical analysis demonstrated a significantly increased sodium content in the skin during experimental autoimmune encephalomyelitis independent of active immunization. In male patients with RRMS, 23Na-MRI demonstrated a higher sodium signal in the area of the skin compared to age- and biological sex-matched healthy controls with higher sodium, predicting future disease activity in cranial MRI. In both studies, the sodium enrichment was specific to the skin, as we found no alterations of sodium signals in the muscle or other tissues. Our data add to the recently identified importance of the skin as a storage compartment of sodium and may further represent an important organ for future investigations on salt as a proinflammatory agent driving autoimmune neuroinflammation such as that in MS.

Permanganate release from silica-based hollow mesoporous coagulant combined with UV for spatiotemporal enrichment and degradation of diclofenac sodium

In this work, the novel hollow mesoporous coagulant was prepared by chitosan-polydopamine coating and permanganate loading into silica nanoparticles for investigating the simultaneous enrichment and degradation of diclofenac sodium (DCFS) combined with ultraviolet irradiation. The enrichment kinetic of DCFS was explained well with pseudo-second-order model, indicating the exist of hydrogen bonding. Based on the correlation coefficients, the enriched isotherms were fitted by models which accorded with the BET > Freundlich > Langmuir sequence. The result showed that, in addition to the coagulant and DCFS, there were aromatic stackings among DCFS molecules. Due to both effects of which, the DCFS enrichment could be realized significantly in the range of pH 4.0–9.0. It was degraded at the copresence of ultraviolet and permanganate released from coagulant in acidic aqueous medium. The release mechanism was simulated through Korsmayer-Peppas model, implying case-II transport and Fickian diffusion. Additionally, Mn (V) and •OH radicals were vital in the DCFS degradation process. The coagulant could be reloaded at least ten times and that from each cycle was used directly for DCFS removal for six times without rinse process, which provided a potential application in environmental remediation.

Salt reduction in bread via enrichment of dietary fiber containing sodium and calcium

The high intake of sodium and low intake of dietary fiber are two major dietary risk factors for preventable deaths worldwide, highlighting the need and implementations for developing health foods with low-salt/high-dietary fibers. Bread as a staple food contributes about 25% to the daily intake of sodium in many countries, and salt reduction in bread still remains a great technical challenge. In this study, we developed a simple method to reformulate the white bread in terms of reducing salt contents via dietary fiber fortification, while maintaining the taste and texture qualities. Low molecular weight water-extractable arabinoxylans (LMW-WEAX) as a soluble dietary fiber was first hydrated in salt water before dough mixing, leading to an inhomogeneous spatial distribution of sodium in bread and accelerating the release of sodium ions from crumbs, allowing 20% salt reduction in bread without impacting the salt perception. Data from the moisture content, crumb structure, water distribution, dough rheology and bread texture properties suggest that the pre-hydrated incorporation of LMW-WEAX mitigates the detrimental effect of dietary fiber on the dough and bread quality. The modulation of Ca2+ on the permeability of Na+ through the mucus layer and implication in salt enhancement of the bread were investigated. Results show that the pre-hydrated incorporation of WEAX containing Na+ and Ca2+ (1.0%) makes it possible to reduce 30% salt content in breads, which have implications in the large-scale production of low-salt/high-dietary fiber bread.

Soil development in weathering pits of a granitic dome (Enchanted Rock) in central Texas

Weathering pits form on various rock types worldwide and often contain unique ecosystems in periodically flooded or desiccated depressions. However, little is known about soil formation in such pits. Here, we investigated two weathering pits (WP1 and WP2) on the summit of Enchanted Rock, a granitic exfoliation dome in central Texas. We aimed at unravelling the origin of the parent material, evaluating evidence for dating the soil development, and identifying the major soil forming processes. We sampled five soil profile cores in each pit and analyzed diverse soil properties, such as C and N contents, pH, exchangeable cations, texture, and iron oxides. In addition, we performed energy dispersive X-ray spectroscopy and applied optically stimulated luminescence (OSL) and 14C dating analyses. Both pits were affected by redoximorphic features and organic matter accumulation (2.5 ± 1.4% C in the topsoil). WP1 revealed Na accumulation in the subsoil and pronounced translocation of clay minerals, which accumulated at the bottom (up to 50% clay in the subsoil, 13–34% in topsoil). Such processes were absent in WP2, in which clay contents and their variations were comparatively small (16–25%). Here, acidic and nutrient poor soil horizons (pH 4.0–4.4, 0.5–1.5% C, 4.1–4.6 mg kg−1P) alternated several times with nutrient rich and neutral soil horizons (pH 5.1–5.6, 2.0–2.5% C, 23–33 mg kg−1P). This phenomenon was observed down to the bottom of the pit. We conclude that the parent material for soil development consists of three sources: autochthonous material from in-situ weathering of the solid rock, granitic grus particles from upslope positions, and eolian sediments from the area surrounding Enchanted Rock. Phases of sedimentation may have alternated with phases of stability and topsoil formation, resulting in buried former topsoils. OSL dating revealed that sedimentation began not later than 5110 years ago in 42 cm depth of WP1 and 2290 years ago in 26 cm depth of WP2. Due to contamination by younger carbon, 14C dates underestimate the beginning of soil development. The intensity of post sedimentary soil forming processes (clay mineral translocation, sodium enrichment, ferrolysis, organic matter accumulation) depends on the age of the pit and on its morphology, i.e. on the possibility of water and dissolved substances running off.

Magnetic Template Anion Polyacrylamide-Polydopamine-Fe3O4 Combined with Ultraviolet/H2O2 for the Rapid Enrichment and Degradation of Diclofenac Sodium from Aqueous Environment.

In this study, a novel system was set up by preparing a magnetic flocculant combining with ultraviolet/H2O2 to realize the rapid enrichment and degradation of diclofenac sodium (DCFS). For the magnetic flocculant, template anion polyacrylamide (TAPAM) with anion micro-block structure was prepared. Thereafter, polydopamine was used to modify TAPAM, Fe3O4 nanoparticles was grafted to the modified TAPAM by chelation, named template anion polyacrylamide-polydopamine-Fe3O4 (TAPAM-PDA-Fe3O4). Furthermore, the TAPAM-PDA-Fe3O4 preparation protocol was optimized by the response surface method (RSM). In the DCFS enrichment section, the rapid separation of flocs from water was realized by an external magnetic field and it indicated that the π–π stacking effect was dominant in neutral/alkaline condition, whereas charge neutralization was favored in acidic conditions. Meanwhile, a DCFS enrichment kinetic curve was much fitted by the pseudo-second-order kinetic model and DCFS enrichment isothermal curve was close to the Freundlich isothermal model, indicating the dependence of DCFS quantity enriched by TAPAM-PDA-Fe3O4 and a multilayer heterogeneous enrichment process. The degradation experiment confirmed that DCFS was effectively degraded by ultraviolet/H2O2/TAPAM-PDA-Fe3O4 and the maximum value of DCFS degradation efficiency reached 98.1%. Furthermore, the regeneration experiment showed that the enrichment and degradation efficiency of DCFS could maintain a relatively high level in the initial three recycles.

Climatic and anthropogenic impact on groundwater quality of agriculture dominated areas of southern and central Gujarat, India

Globally natural and human interference is affecting aquifer recharge and quality of ground water. This study focuses on changes in groundwater hydrochemistry in south and central part of Gujarat state in India to identify vulnerable hotspots under seasonal variations and anthropogenic activities. Forty-five groundwater and soil samples were collected over three seasons from random locations of south and central Gujarat. The samples were analyzed for physico-chemical characteristics. Dominance of cations and anions during post-monsoon was in higher to lower order of Na, Mg, Ca, K and Cl−, SO42−, HCO3− in groundwater. The Piper classification for hydrogeochemical facies indicates all monsoon samples were of Ca–Cl type. Residual sodium carbonate values revealed that 46% samples were not suitable for irrigation purposes in pre-monsoon. Samples collected during post-monsoon from Vyara and Ukai and during pre-monsoon from Central Gujarat were of doubtful to unsuitable category as per Wilcox's diagram. During the post-monsoon season, moderate and bad quality water rose owing to the enrichment of sodium and electrical conductivity. The groundwater quality in post-monsoon for all constituents were higher at some places due to dissolution of surface pollutants and infiltration after flooding with percolation of rainwater. None of the samples from pre-monsoon fell under Class-I category (Permeability index >75%) due to leaching of ions through industrial, agricultural or domestic discharges. Soil permeability index varied from monsoon to post- and pre-monsoon. Groundwater quality of Vadodara, Bharuch, and Tapi districts were affected by geological and anthropogenic activities while ground water in Vansda and Ahwa were less affected due to limited industrialization as well as geographical location. The cumulative hydrochemistry during post- and pre-monsoon was found to be higher than permissible limits due to leaching of contaminants. Judicious management of efficient irrigation, industrial waste treatment, modern agricultural practices, rainwater harvesting to conserve groundwater quality of study area are critical.

The Late-Paleoarchean Ultra-Depleted Commondale Komatiites: Earth's Hottest Lavas and Consequences for Eruption

Abstract The c.3·3 Ga Commondale komatiites located south of the Barberton greenstone belt in the Kaapvaal Craton are different from other komatiites, possessing compositional and textural features unique to this occurrence. Unlike almost all other known komatiite occurrences, they are not associated with komatiitic basalts or basalts. The komatiite flows are 0·5–25 m thick and are made up of a marginal zone of spinifex-textured and fine-grained aphyric rocks (low-Mg group) and an inner zone of olivine cumulates (high-Mg group), arranged in such a way to give highly symmetrical compositional profiles for many flows. Olivine is the dominant phase in all rocks, but orthopyroxene occurs as spinifex and elongate laths in the marginal zone. Clinopyroxene and plagioclase are entirely absent. The olivine cumulates formed from Mg-rich magma (36·1% MgO, 6·8% FeO) which caused inflation of the thicker flows. The maximum observed olivine composition in cores (Fo 96·6) is the highest recorded for any komatiite worldwide. The high-Mg magma would have erupted at a temperature close to 1670°C, the highest inferred temperature for an anhydrous terrestrial lava. The marginal zone is enriched in incompatible elements compared with the inner zone and formed by fractionation of the parental melt. However, all rock-types in the marginal zone are depleted in FeO (some as low as 3·5%) which could not have been derived by any primary magmatic process. The marginal zone rocks were modified by assimilation and/or alteration by seawater (or brine) components causing migration of iron and strong enrichment of sodium (up to 1·6 wt % Na2O) and chlorine (up to 2400 ppm). Zirconium has an identical distribution to sodium, with both elements greatly enriched above what would result from fractional crystallization, and may result from speciation of these elements at high temperature followed by post-crystallization alteration. Rare earth elements, Y and Nb have contents commensurate with fractionation of the primitive parental magma. Dendritic-textured olivine-rich rocks with orthopyroxene spinifex spatially and compositionally transitional between the marginal zone and the olivine cumulates resulted from interaction of the high temperature parental magma in the centre of the flows with the fractionated melt at the flow margins. A further manifestation of this association is the development of highly regular fine-scale (5–15 cm) layering (up to 45 layers) of alternating olivine cumulate and spinifex near the base of thick flows. This is overlain by olivine cumulates in which the melt/crystal-mush became arranged into a 3-dimensional network controlled by re-distribution of the trapped melt manifest by a spectacular knobbly texture in outcrop. Over 200 flow units are recognized and detailed chemical and mineralogical studies were carried out on drill cores intersecting 375 m of stratigraphy. The parental magma was highly depleted (in ppm Nb 0·017, Zr 1·18, total REE 1·7 and Gd/YbN=0·3, La/YbN=0·038) and although generally regarded to fall into the rare category of Al-enriched komatiites (AEKs), it is considered that these lavas are a unique class of their own of ultra-depleted komatiites. Relative to other AEKs the Commondale komatiites are both enriched in Al as well as being markedly depleted in Ti (390 ppm), giving rise to the extremely high Al2O3/TiO2 (81). The high temperature and low viscosity of the magma resulted in emplacement processes previously unrecognized in komatiites. The primary melt was derived by melting of mantle peridotite in equilibrium with olivine and orthopyroxene. The initial source was depleted in incompatible elements by small degrees of melting (3–4%) followed by high degrees of partial melting (70%) of the subsequent refractory source at 5 GPa (∼150 km).

Insights into phase and mineral matter of metallurgical coke in cohesive zone

A series of coke samples collected from cohesive zone were examined by SEM/EDS. The forsterite, octahedral spinel crystal and silicon reduced from quartz particles were found in coke. Besides the coke, the alkalis aluminosilicate minerals were also distributed in the slag, iron and iron oxide layer. Many spinel crystalline phases presented in the slag will increase the slag viscosity and affect slag flow through the coke bed. The coexistence of sodium enrichment and graphite precipitated from iron phase implies key clues for the formation of intercalation compounds with micro graphite crystals of coke, probably providing an additional degradation mechanism for the coke in cohesive zone. Iron sulfides, iron phosphides, reduced silicon and the crystalline phases rich in Ca-Al were expected to affect the coke carbon-dissolution reaction.

Bulk, surface structures and properties of sodium borosilicate and boroaluminosilicate nuclear waste glasses from molecular dynamics simulations

The bulk and surface structures, as well as physical properties such as ionic diffusion and mechanical moduli, of sodium borosilicate and boroaluminosilicate model nuclear waste glasses with composition similar to the international simplified glass (ISG) have been studied using molecular dynamics simulations with the recently developed partial charge composition dependent potentials. Short and medium range structures of these glasses were analyzed and it was found that, for glass former cations, silicon ion is all four-fold coordinated by oxygen, aluminum is also mainly four-fold coordinated, while boron exists in a mixture of 3- and 4-fold coordination, with the fraction of 4-fold coordinated B (N4 value) close to but slightly higher than the experimental and theoretical values. The medium range structure features such as network former cation oxygen polyhedral connectivity, sodium distribution around the network formers, and network ring size distribution were characterized. The surface structure was generated from the simulated bulk glass structures and showed sodium enrichment on the glass surface. Addition of alumina to borosilicate glasses increased B N4 value and overall glass network connectivity that led to improved mechanical properties. Ion diffusion properties, mechanical properties as well as surface characteristics for the simplified ISG have also been investigated with simulations and compared with available experimental data. This detailed atomic structure information provides insight of the physical properties of these glasses and a step further in understanding the chemical durability and dissolution behaviors.

Groundwater chemistry characterization using multi-criteria approach: The upper Samalá River basin (SW Guatemala)

Improving understanding on groundwater chemistry is a key priority for water supply from groundwater resources, especially in developing countries. A hydrochemical study was performed in an area of SW Guatemala (Samalà River basin), where water supply to population is groundwater-based and no systematic studies on its groundwater resources have been performed so far. Traditional hydrochemical analyses on major ions and some trace elements metals coupled with chemometric approach were performed, including principal component analysis and hierarchical clustering analysis. Results evidence that chemical differentiation is linked to the spatial distribution of sampled waters. The most common hydrochemical facies, bicarbonate calcium and magnesium, is linked to infiltration of meteoric waters in recharge areas represented by highlands surrounding Xela caldera, a wide plateau where most of population is concentrated. This trend undergoes chemical evolution in proximity of active volcanic complexes in the southern area, with enrichment in sulphate, chloride and magnesium. Chemical evolution also occurs towards the centre of Xela caldera due to slow circulation in aquifer and consequent sodium enrichment due to ion exchange with the porous medium. Water quality did not reveal severe concerns, even though some sources of contamination could be identified; in particular, agriculture and urban wastewater could be responsible for observed threshold exceedances in nitrate and lead.This integrated multi-approach to hydrochemical data interpretation yielded to the achievement of important information that poses the basis for future groundwater protection in an area where main water features were almost unknown.