Silicate Groups Research Articles

Supreme capture of Europium(ΙΙΙ) by silica-hyperbranched poly(ethylene imine) composites from aqueous solutions − A mechanistic study

Two bio-inspired variations of the sol–gel technique produced silica-hyperbranched poly (ethylene imine) (PEI) composite nanoparticles (NP) and xerogels (XG). Both methods are performed in ambient conditions and do not require toxic organic solvents or high temperatures. We have investigated the removal efficiency of trivalent europium by these two hybrid species in near-neutral aqueous solutions. The adsorption kinetics and isotherms, including data fitting with the pseudo-first and second order kinetic, and the Langmuir isotherm model are presented and discussed. Thermodynamic parameters indicate exothermic reaction (–180 kJ/mol for NP and –192 kJ/mol for XG, respectively) In addition, spectroscopic (Fourier Transform Infra-Red FTIR, Fluorescence Spectroscopy FS, X-ray Photoelectron Spectroscopy XPS) and microscopic techniques (Scanning Electron Microscopy SEM coupled with Energy Dispersive X-ray analysis EDX), as well as ζ-potential and Dynamic light scattering (DLS) measurements, have been employed to evaluate the interaction mechanism between the surface active moieties and Eu(III). The extremely high and homogeneous dispersion of the amino and silicate groups of the composites has led to the highest capacity value (22 mmol/g or 3343 mg/g and 14 mol/g or 2128 mg/g for the two distinct forms of the nanoparticles and the xerogels, respectively) reported up to today implying a potential application for lanthanide recovery. The adsorption data along with the spectroscopic and microscopic indicate that the adsorption is well described by the Langmuir isotherm model and is based on the formation of inner- and outer-sphere complexes between Eu(III) the amine and −Si-O− moieties.

How distinctive are ‘Gewürztraminer’ vineyard terroirs in South Tyrol for wine production? A metabolomics-based approach

Vitis vinifera L. ‘Gewürztraminer’ produces distinctive, aromatic wines that are strongly influenced by their terroir. This metabolomic study used a data-driven approach, including Principal Component Analysis (PCA) and Multifactorial Analysis (MFA), to correlate a quali-quantitative multivariate concept of terroir (including soil characteristics, and altitude) with sensory, phenolic, antioxidant, and volatile profiles of wines. The study analyzed wines from seven ‘Gewürztraminer’ vineyards, chosen to minimize the variability due to climate differences. Based on the soil data, the vineyards were clustered into two distinct groups: clay silicate (Group A) and dolomitic (Group B) soils. Group A exhibited lower levels of aromatic compounds such as linalool and higher levels of phenolic compounds such as gallocatechin than Group B. These findings indicate that even small changes in terroir within the same region can significantly impact the chemical, functional (antioxidant), and sensory properties of ‘Gewürztraminer’ wines, highlighting the importance of terroir in wine production. Statistical analyses confirmed the significance of these correlations (p < 0.05), highlighting the need for further research into the intricate relationship between terroir and wine quality.

Toxicity of vapor-gas flows from technogenic substance

The relevance. Vapor-gas flows from technogenic substances (storage wastes of the mining industry), carrying a high amount of potentially toxic elements, are a big problem for the environment and the population, because metals and metalloids in the composition of emanations are in an easily digestible bioavailable forms and are able to easily penetrate into living organisms. The main aim of this study is an assessment of toxicity for living organisms of air mixtures containing gaseous products emitted by a surfaces of mine tailings freely located near settlements and under the influence of climatic factors and microorganisms. Methods. Carrying out experiments with white rats male Wistar, analysis of organs for the content of a wide range of elements by ICP-MS on a NexION 300D mass spectrometer (PerkinElmer, USA) (PNL GGC IShPR TPU). In the experiment, a pooled sample of the waste substance was used. The sample was analyzed for the content of oxides of the silicate group by XRF using X-ray fluorescence spectrometer ARL-9900-XP (Thermo Electron Corporation, Switzerland) at the Laboratory of X-ray Spectral Analysis Methods of the IGM SB RAS; elemental analysis was carried out by ICP-MS using an ELAN-9000 DRC-e instrument Perkin Elmer, USA (HAC Plasma). Results. Under the influence of vapor-gas emanations from the substance of arsenide tailings of the Tuvacobalt plant on a group of rats male Wistar, pathological changes occurred in the experimental group. Small foci of hemorrhages formed in the lungs, the tissues became edematous and inflamed. The liver of all animals increased, the share structure became sharply expressed, the color became light beige. Single hemorrhages were found in the kidneys. The vessels of the meninges are dilated, petechial hemorrhages are observed. The synthetic function of cells and the stability of cellular and intracellular membranes were disrupted, first of all, the endothelium of blood vessels was affected, the physiological functioning of organs and tissues was disrupted with the accumulation of intermediate products of biochemical reactions, determined macroscopically. Also, dystrophy of internal organs was determined, in particular, the liver, lungs, kidneys, and brain. Elemental analysis of animal organs showed the accumulation of toxic elements in comparison with the control group. The most characteristic elements, the excess of which was recorded in most cases, are mercury and arsenic. They were unevenly distributed throughout the organs. Mercury accumulated mainly in the lungs, kidneys and liver, while arsenic accumulated mainly in the liver and brain. This may indicate the entry of mercury and arsenic ions in a biologically available form into the bloodstream by inhalation, and local irritating and toxic effects on the lungs were not prevailing, and the liver was the most damaged organ according to the results of toxicochemical and morphological studies. The homeostasis of micro and macro elements is finely regulated, and any concentration imbalance in the form of a deficiency leads to a progressive decrease and disruption of normal biological function, to severe physiological and clinical outcomes, which we observed from the results of the experiment. The data obtained proved the acute toxic effect of vapor-gas flows on living organisms, and also confirmed the possibility of the removal of many chemical elements in easily accessible and assimilable forms.

Comprehensive characterization of unscientifically disposed municipal solid waste (MSW) in Kashmir Region, India.

Unscientific dumping of municipal solid waste (MSW) is a common practice in Kashmir. To have an environmentally friendly and sustainable waste management system, MSW was collected from nine study locations of this region. They were air-dried, then oven-dried at 105°C for 24h, segregated, and characterized for various components. The overall average organic waste was > 55%, plastic waste about 17%, inert material about 10%, paper 9%, and cloth waste 7%. The calorific value of paper and plastic wastes exhibited was 4910kcal/kg, while organic waste had a calorific value of 1980kcal/kg. The proximate analysis showed that the moisture content ranged from 16 to 29%, volatile matter ranged from 49 to 72%, ash content ranged from 0.03 to 5%, and fixed carbon ranged from 5 to 20%. In S7, the volatile matter content recorded the lowest value at 49.15%, while in S5, the volatile matter content was notably higher at 71.84%, indicating easier ignition. Further, elemental analysis revealed that the major elements in MSW were carbon and oxygen, 53% and 37%, respectively, with small traces of heavy metals with an average of 0.02% cadmium (Cd) and 0.006% lead (Pb). Moreover, field emission scanning electron microscopy (FESEM) micrographs provided confirmation that the majority of components in the MSW exhibited either partial or complete degradation, resulting in a rough surface texture. In addition, the presence of silica and other silicate groups was also detected. Fourier transform infrared spectroscopy (FT-IR) analysis revealed that the main functional groups were alcohol. In the X-ray diffraction (XRD) analysis, all the major mineral phases were detected between 20 and 30° 2θ, except for the peaks at 50-60° 2θ in S3 and S9 where catalysts such as zeolite Y and zeolite X were detected. Overall, the MSW had low moisture content but higher calorific value, making it a viable feedstock.

Modified approach to calculate brittleness index in shale reservoirs

The successful production of unconventional reservoirs through hydraulic fracturing is heavily dependent on the brittleness of the shale's. To precisely evaluate rock brittleness the mineral-based brittleness indices are considered reliable. Initially, only the weight fraction of quartz accounted for mineralogical brittleness, later dolomite was included in the group, further, it was divided into the silicate and carbonate groups. Due to its heterogeneous nature, shales contain some other minerals, however, the impact of these minerals on rock brittleness has yet to be analyzed. The mineral pyrite is commonly found in shales but its impact on rock brittleness is still undefined. In this research, we proposed a modified mineral-based brittleness index including mineral pyrite, and investigated its impact on rock brittleness. The modified index was evaluated using the data from three different shale reservoirs in China. In the next step, the Fracability Index (FI) model of rocks including pyrite mineral is calculated, and finally, the rock physics modeling is performed to evaluate the elastic response of the rock to this mineral. The modified brittleness index was found to be more accurate in predicting rock brittleness than other mineral-based brittleness indices. The correlation between the modified brittleness index and the FI model was higher than the correlation with other mineral-based brittleness indices. Further, rock physics modeling also proved that the rock with high pyrite content has low Poisson's ratio and high Young's modulus.. These properties are associated with brittle rocks, which further supports the inclusion of pyrite as a brittle mineral in the modified brittleness index. Hence, the findings of this research indicate that the modified brittleness index based on minerals is a reliable approach for predicting rock brittleness in shale reservoirs that contain pyrite. This study has an important application for the development and management of shale reservoirs. The modified brittleness index can be used to identify rocks that are more likely to be successfully fractured during hydraulic fracking process. Keywords: shale reservoirs; hydraulic fracturing; mineral brittleness; fracability index.

Weathering as a control on the triple oxygen isotopes of groundwater-associated ferromanganese deposits: lessons from the Grimlock Ni–Co–Mn prospect, Northern Territory, Australia

At the Grimlock laterite deposit (Northern Territory, Australia), Co and Ni mineralization occurs mainly in the Mn-oxide rich layers of the ferromanganese (Fe-Mn) crust overlying ultramafic bedrock. Groundwater-associated Fe-Mn crusts consist of mineral (e.g. Mn-oxide, Fe-oxyhydroxide and silicate) groups suitable for studying triple oxygen isotopes and present unique interpretative challenges (e.g. small Mn-oxide fractions relative to Fe-Mn precipitates from other formation environments and extensive weathering). We evaluate triple oxygen isotopes within the context of changes to properties (i.e. mineralogy, major and trace element geochemistry, and degree of weathering) of a lateritic profile. We use pre-existing mineral-water fractionation factors, meteoric water δ 18 O and temperature data to calculate δ 18 O values of fully altered mineralogical endmembers, then, using mass balance, discuss scenarios to elucidate measured whole-rock δ 18 O values. The δ ′ 18 O (′ denotes linearized notation) and Δ ′ 17 O of near-surface samples (0–8 m) are generally lower (mean of 8.892‰) and higher (mean of −0.141‰), respectively, than the δ ′ 18 O (mean of 12.767‰) and Δ ′ 17 O (mean of −0.176‰) of samples from greater depths (19–22 m). At 16–17 m depth, δ ′ 18 O and Δ ′ 17 O are relatively high (means of 17.509 and −0.118‰, respectively). The measured whole-rock δ 18 O values are explainable by substituting lower δ ′ 18 O values for the Mn-oxide and Fe-oxyhydroxide fractions, and higher δ ′ 18 O values for the aluminosilicate fraction, changes coinciding with greater alteration. These results suggest that mineral weathering is primarily responsible for observed variations in the triple oxygen isotopes of groundwater-associated Fe-Mn crusts, rather than variation in the initial source of oxygen incorporated into Mn-oxide. Supplementary material: Grimlock sample photographs, XRD patterns and supplementary figures and tables are available at https://doi.org/10.6084/m9.figshare.c.7071907

Temperature-sensitively dissolving of GGBS in neutral and alkali media

The sensitivity of temperature on the decomposition/polymerisation of ground granulated blast-furnace slag (GGBS) was investigated through the dissolution experiments at high water to solid ratio under controlled temperatures (5, 20, and 40 °C). The aqueous compositions during the dissolution in neutral and alkali media were determined by ICP-OES (Inductively coupled plasma-optical emission spectrometry) and the saturation conditions with respect to the possible precipitations were estimated by thermodynamic modelling. The depolymerisation of silicate groups and the chemically combined water in the residual GGBS was examined by FTIR/SEM (Fourier Transform Infrared spectroscopy/Scanning Electron Microscopy) and TG (Thermogravimetric) analysis respectively. The results demonstrated that the effect of temperature on the dissolution of GGBS is more pronounced from 5 °C to 20 °C than that from 20 °C to 40 °C. The extremely low temperature (∼ 5 °C) restricts the hydration of GGBS even in a high pH environment. The temperature does not affect the depolymerising sequences of silicate groups in GGBS in a neutral environment but changes the overall dissolution rate. The major silicate spices (Q0 to Q3) in GGBS tend to dissolve evenly in DI water, whereas the Q2 tends to depolymerise faster than others in the NaOH solution. The decreasing Ca concentration in the NaOH solution corresponds to the formation of ∼ 50 nm needle-like precipitates regardless of temperature. Based on the results collected, the dissolving potential and the temperature sensitivity of the major components in GGBS can be divided into three batches: the easiest/most sensitive group: Na-Ox; intermediate group: K-Ox, Si-Ox, Ca-Ox, Al-Ox; the hardest/least sensitive group: Mg-Ox. The intermediate batch required an initial activation energy of ∼ 15 kJ/mol in DI water. The relevant data could be considered as experimental evidence in the thermodynamic modelling of the hydration of GGBSs.

Silica Based Material as a Potential Adsorbent in Reducing Sterol Glucoside Level in Palm Oil Biodiesel

In recent years, biodiesel has emerged as a popular alternative to fossil fuels due to its superior properties. However, the presence of bioactive compounds, known as sterol glucosides (SGs), in crop-based biodiesel has posed a challenge for producers, as they act as crystal seeds and can cause gel formation or precipitation in cold temperatures. This can lead to issues with the quality of biodiesel during storage or use in vehicle engines. To address this issue, a study was conducted to explore the use of silica-based materials as an adsorbent to reduce SGs concentration in palm oil biodiesel. Natural resources silica material with a size of less than 100 µm was used in the process. The results showed that the use of silica gel led to the removal of 63.09 % of SGs in palm-based biodiesel due to its high surface area (556 m2/g) and porosity (0.79 cm3/g). Fourier transform infrared spectroscopy (FTIR) analysis indicated that the silicate and hydroxyl groups on the adsorbent’s surface were responsible for SGs adsorption. Importantly, the quality of the biodiesel before and after the adsorption treatment met all the specifications of the EN 61214 standard. This research suggests that the use of silica-based materials could be a promising solution for reducing SGs concentration in crop-based biodiesel, and could potentially improve its overall quality.

Understanding the setting behaviours of alkali-activated slag from the dissolution-precipitation point of view

Ground granulated blast-furnace slag (GGBS) is widely used as supplementary cementitious material of interest for adjusting the performance of concrete. Unlike standard commercial products, characteristics of GGBS from different iron manufacturers vary significantly and assessment of its reactivity, especially at an early age, is not well-established despite numerous parameters specified in current standard systems. Three GGBSs with different setting features during the alkali-activated process were dissolved in either deionised (DI) water or NaOH solution in this study. To illustrate the fundamental processes of reaction kinetic, the dissolved ion concentrations, glassy structural changes, and chemically bound water were measured using ICP-OES, FTIR, and TG respectively. Meanwhile, thermodynamic calculations were carried out to estimate the precipitation of C–S–H gels, which is directly linked with setting behaviours. The results clearly show the differences in the dissolution of the three GGBSs, which could be used to indicate the activity of GGBS. The GGBS with higher activity (i.e. faster setting during alkali activation) tends to dissolve evenly in DI water, whilst those with lower activity show that the silicate groups with lower polymerisation dissolved faster. The chemically bound water determined by TG analysis and the effective saturation index (ESI) are promising parameters for reflecting the activity of GGBS during dissolution in the alkali media. Although this study demonstrated the dissolution rate of higher polymerised silicate groups in GGBS should be the root for the differences in its activity, more structural information on the glassy phase and the interactions of alkali with the surface of GGBS still require further understanding. It is speculated that the ratio of Al[IV]/Al[V] plays an important role in the activity of GGBS. This finding may shape a certain basic understanding of how GGBSs dissolve in neutral and high pH solutions and highlight a re-evaluation of assumptions in thermodynamic simulation under different conditions.

Influence of Transition Metals on the Development of Semiconducting and Low Thermal Expansion TiO2-Borosilicate Glasses and Glass Ceramics

This current investigation represents as well as discusses in detail the characterization of the thermal, mechanical, as well as electrical characteristics of titanium-based borosilicate glasses doped transition metal ions (3d) in addition to their corresponding glass–ceramics. The building structural units of the as-prepared glasses together with their glass – ceramic were characterized by the FTIR technique. FTIR spectra reveal characteristic silicate and borate groups vibrations, some of the TiO4 units are formed beside (TiO6) groups. The progressive enhancement in microhardness and thermal expansion values was recorded for glass – ceramic state that occurred as a result of the crystallization of nano-sized crystals throughout the glass matrix. The estimated electrical parameters which include permittivity (ε'), dielectric loss (ε''), AC conductivity (σac) capacitance (C), and dielectric loss demonstrated a distinctive variation in their values in accordance with the type of transition metal and /or the applied frequency. The prepared glass–ceramic was found to be suitable for use in electronics and solar cell applications based on its overall thermal and electrical properties.

Role of Gd3+ ions in alumino borosilicate glasses studied through structural, optical and thermoluminescence characteristics for gamma dosimetry applications

This paper reports the structural, optical and thermoluminescence properties of Gd3+ ions incorporated alumino-borosilicate glasses, prepared through the melt-quench technique. The amorphous nature of the glasses is confirmed through XRD study. Network vibrations of borate and silicate groups, vibrations of hydrogen bonding and hydroxyl groups are realized via FTIR study. The Gd3+ transition peaks are absent in the near ultraviolet, visible and NIR regions, and the indirect bandgap values were determined through UV–Visible–NIR study. Photoluminescence measurements showed a concentration quenching in the glasses beyond 1.5 mol % of Gd3+ ions. Based on the thermoluminescence (TL) data, the 2 mol % of Gd2O3 doped glass (BSGD5) was chosen as optimum sample because of the presence of maximum TL intensity. The BSGD5 glass displayed TL response linearity in 0.25–1 kGy dose region giving a high signal sensitivity of 220,068 counts. g−1 kGy−1 in this region. With nearer tissue equivalence and a minimum detectable dose of 0.02 Gy, the suitability of BSGD5 glass for gamma dosimetry application was deducted. Electron spin resonance (ESR) study validated the presence of intrinsic defects in Gd3+ glasses which are responsible for changes in the intensity and shape of TL glow curves. Hence, from the obtained results Gd3+ doped alumino borosilicate glasses can be considered as potential candidates for gamma dosimetry application.

Multifunctional bioactive coating on biomedical β-Ti12Mo6Zr2Fe alloy to improve corrosion protection and bioactivity properties

The present work presents and discusses the results of a comprehensive electrochemical study of the laser-textured β-Ti12Mo6Zr2Fe (TMZF) alloy coated with a bioactive layer (TMZF-BL), which was strategically designed to produce an improvement in corrosion resistance and impart bioactive properties to the TMZF alloy. The bioactivation of the laser-textured TMZF alloy was performed using a simple and innovative strategy that effectively coated the metal surface with a bioactive layer structured with bioactive glass (BG) particles functionalized with silicate and phosphate groups, acting as chemical anchoring agents. The electrochemical corrosion behavior of the bare and coated TMZF was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in Simulated Body Fluid (SBF) at 37 °C. Our results showed that the presence of the bioactive layer in the TMZF-BL samples shifted the corrosion potential (Ecorr) towards more noble values compared to polished TMZF (TMZF-P), and increased EIS modulus, suggesting that the corrosion resistance improved. The chemical stability of the bioactive coating was confirmed by the high polarization resistance and low capacitance values. Various analysis techniques surveyed the apatite-forming ability and growth on the surface of TMZF-P and TMZF-BL alloys as a function of soaking time in SBF. The bone-like apatite formation rate depended on the homogeneity of the bioactive layer covering the surface of the TMZF-BL alloy. Taken together, our results confirm the success of the experimental strategy designed to bioactivate the TMZF alloy and reinforce the potential of this approach for the development of highly stable bioactive implants, in addition to protecting the alloy surface against corrosion in the physiological environment.

Mineralogical analysis and firing temperature of the ancient potteries of Tamil Nadu using spectroscopic techniques

Our curiosity about archaeological artefacts leads us to discover details about the lifestyles of our ancestors. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDX), and thermogravimetry differential thermal analysis (TG-DTA) techniques have been used to characterize the ancient potteries unearthed at the recently excavated archaeological site of Palayanur, Tamil Nadu. Minerals such as quartz (silicate group), feldspar, clay minerals (illite), calcite, hematite, magnetite, and organic carbon were identified from FT-IR analysis. Quartz had been detected in all of the samples, as evidenced by the significant absorption peaks at 794 cm−1, 795 cm−1, 779 cm−1, 780 cm−1, 781 cm−1, and 695 cm−1. The obtained 2θ values from the XRD spectrum validated the mineral’s presence as well as the pottery’s firing condition and temperature. The presence of calcite indicates that these samples were fired below 850 ℃, and the presence of hematite in the potteries indicates that they were fired in an oxidizing atmosphere. The elemental concentration and microstructure of collected pottery samples were determined by the SEM-EDX technique to elucidate the nature of the raw material used for making pottery samples.

Investigations on the polymorphism of K4CaSi6O15 at elevated temperatures.

In the present study, single crystals and polycrystalline material of K4CaSi6O15 were prepared from solid-state reactions between stoichiometric mixtures of the corresponding oxides/carbonates. Heat capacity (C p) measurements above room temperature using a differential scanning calorimeter indicated that two thermal effects occurred at approximately T 1=462 K and T 2=667 K, indicating the presence of structural phase transitions. The standard third-law entropy of K4CaSi6O15 was determined from low-temperature C p's measured by relaxation calorimetry using a Physical Properties Measurement System and amounts to S°(298K)=524.3±3.7 J·mol-1·K-1. For the 1st transition, the enthalpy change ΔH tr1=1.48kJ·mol and the entropy change ΔS tr1=3.25 J·mol-1·K-1, whereas ΔH tr2=3.33kJ·mol-1 and ΔS tr2=5.23 J·mol-1·K-1 were determined for the 2nd transition. The compound was further characterized by in-situ single-crystal X-ray diffraction between ambient temperature and 1063 K. At 773 K, the high-temperature phase stable above T 2 has the following basic crystallographic data: monoclinic symmetry, space group P21/c, a=6.9469(4) Å, b=9.2340(5) Å, c=12.2954(6) Å, β=93.639(3)°, V=787.13(7) Å3, Z=2. It belongs to the group of interrupted framework silicates and is based on tertiary (Q3-type) [SiO4]-tetrahedra. Together with the octahedrally coordinated Ca-cations, a three-dimensional mixed polyhedral network structure is formed, in which the remaining K-ions provide charge balance by occupying voids within the net. The intermediate temperature modification stable between T 1 and T 2 shows a (3+2)-dimensional incommensurately modulated structure that is characterized by the following q-vectors: q1=(0.057, 0.172, 0.379), q2=(-0.057, 0.172, -0.379). The crystal structures of the high- and the previously studied ambient temperature polymorph (space group Pc) are topologically equivalent and show a group-subgroup relationship. The index of the low- in the high-symmetry group is six and involves both, losses in translation as well as point group symmetry. The distortion is based on shifts of the different atom species and tilts of the 4- and 6-fold coordination polyhedra. Actually, for some of the oxygen atoms, the displacements exceed 0.5 Å. A more detailed analysis of the distortions relating to both structures has been performed using mode analysis, which revealed that the primary distortion mode transforms according to the Λ1 irreducible representation of P21/c. However, other modes with smaller distortion amplitudes are also involved.

Four-dimensional characterization of a PFOA-contaminated fractured rock aquifer (FRA) in Bennington, Vermont, U.S.A

Between 2016 and 2019, the Vermont Department of Environmental Conservation discovered that groundwater from over 50% (355/628) of wells and springs in the Bennington area had perfluorooctanoic acid (PFOA) concentrations &amp;gt; 20 parts/trillion (ppt) (Vermont action level). The distribution of contaminated wells was complex, with very different PFOA concentrations in closely-spaced wells (&amp;lt;100 m apart). PFOA was introduced into the environment by a factory that produced Teflon™-coated fabrics from about 1978–2002. Manufacturing involved PFOA expulsion from smokestacks followed by atmospheric transport, deposition, and downward leaching to the aquifer system. The fractured rock aquifer was characterized through physical components (geologic mapping, spatial analysis of wells, and geophysical logging) to build a Three-dimensional conceptual model and then map the spatial distribution of chemical groundwater tracers (PFOA, major and trace elements, stable isotopes, and and recharge ages), adding a fourth temporal dimension. The field area consists of four imbricated metamorphic rock slices bounded by thrust faults. The dominant fracture sets that overprint these slices control the N-S and E-W topographic “grain.” Geophysical logging divided wells into those completed internal to or on the margins of thrust slices. Major and trace element analysis shows that groundwater can be spatially discriminated into carbonate (TDS, Ca, Mg, HCO3), shaly (Sr, U, SO4), and siliceous (K, Si) groups. Depleted H2O stable isotope signatures characterize the siliceous group. Recharge-ages determined from CFC11, 12, and 113 and tritium correlate with geochemical groups and were divided into “older” (~1953–73) and “younger” (1963–88), which predate and are synchronous with factory operation, respectively. Our conceptual model shows recharge from highlands to the west and east flowing toward the Bennington valley where it is locally tapped by wells along thrust faults or fracture zones. This water has older recharge ages and anomalously low PFOA concentrations (&amp;lt;6.7 ppt in 12 of 15 samples, mean = 7.9 ppt) compared to the majority of wells in this region, which are completed in the internal portions of thrust slices. These wells contain groundwater with younger recharge ages and high PFOA concentrations (mean = 290 ppt) and occurrence (&amp;gt;20 ppt in 28/36 samples), indicating mixing of younger and older waters.

Thermal Stability of Iron- and Silicon-Substituted Hydroxyapatite Prepared by Mechanochemical Method

In this study, hydroxyapatite with the substitution of calcium cations by iron and phosphate by silicate groups was synthesized via a mechanochemical method. The as-prepared compounds have the general formula Ca10−xFex(PO4)6−x(SiO4)x(OH)2−xOx/2 with x = 0–1.5. The thermal stability of the as-prepared compounds was studied by ex situ annealing of powders in a furnace. It has been established that, at 800 °C for x ≤ 0.5, a partial decomposition of the substituted apatites occurs with the formation of the β–Ca3(PO4)2 phase. At high “x” values, the formation of this phase starts at the lower temperature of 700 °C, followed by the formation of Fe2O3 at 900 °C. The introduction of iron and silicate ions into the hydroxyapatite lattice was shown to decrease its thermal stability.

Histopathological, biochemical and molecular studies on a model of systemic autoimmune disease induced by sodium silicate in non-genetically prone rats

Sodium silicate (Na2SiO3) is an inorganic silica salt used in many products. Few studies reported autoimmune diseases (AIDs) due to Na2SiO3 exposure. This study investigates the role of Na2SiO3 exposure by different routes and doses in AID development in rats. We assigned 40 female rats to four groups: G1 control group, G2 rats were subcutaneously injected with 5 mg Na2SiO3 suspension, and G3 and G4 rats were orally administered 5 mg and 7 mg Na2SiO3 suspension, respectively. Na2SiO3 was administered weekly for 20 weeks. Serum anti-nuclear antibodies (ANA) detection, histopathology of kidney, brain, lung, liver, and heart, oxidative stress biomarkers (MDA and GSH) in tissues, Matrix metalloproteinase activity in serum, TNF-α, and Bcl-2 expression in tissues were performed. ANA was significantly increased in silicate groups, especially G2. Creatinine was significantly increased in silicate groups. Histopathology revealed vasculitis and fibrinoid degeneration of blood vessels, a picture of immune-mediated glomerulonephritis in the kidneys, and chronic interstitial pneumonia with medial hypertrophy of pulmonary blood vessels. The activity of gelatinases (MMP-2 and MMP-9) and collagenase (MMP-13), which play role in inflammation, remodeling, and immune complex degradation, were significantly increased in the silicate-exposed groups. Bcl-2 was significantly decreased, indicating apoptosis. Therefore, oral administration and subcutaneous injection of Na2SiO3 induced immune-mediated glomerulonephritis with elevated ANA levels and overexpression of TNF-α in rats.

Radial differentiation of chemical composition of cryogenic soils in the Chara river valley, north of Transbaikalia

The subject of the study is the content of iron compounds and their radial differentiation in the profiles of cryogenic soils of the Chara River valley (Transbaikalia). The studied soils belong to post-pyrogenic permafrost gleyzems, the depths of the seasonal active&amp;#8208;layer of these soils are from 34 to 44 cm. Macronutrient concentrations, with the exception of Si, rarely exceed 5.0%, while the silicon content reaches 24.3%. Si is also characterized by removal from the upper part of soil profiles and accumulation in permafrost soil horizons. The highest concentrations are characteristic in the O horizons (Mg – 4.8 and Ca – 1.5 mg/kg) for a significant part of the macroelements. The trace elements, Sr and Zr are distributed vary contrastingly (from 5.0 to 29.7 and from 5.6 to 47.1 mg/kg). Values of the R coefficient from 0.3 to 0.9 indicate the initial stage of post-pyrogenic restoration of soil properties, and the active accumulation of Mg, Ca, Ti, Fe, Sr, and other elements in the upper part of oxidized-gley permafrost gleyzem observed in the profile is a sign of active restoration. The soils contain about 3.4% iron, which more than 60–75% is the silicate group of compounds (Feс). The moisture content of soils and the prevailing reducing environmental conditions contribute to the formation of monotonous distributions in their profiles, and in soils without signs of stable hydromorphism, permafrost horizons contain almost 2 times more Feox and Feextr.

Preparation and characterization of mesoporous Lanthanum-doped bioactive glass nanoparticles

In this study, novel compositions of mesoporous Bioglass (BG) and Lanthanum-doped BG (La-BG) were prepared using the sol-gel method. Microstructure analysis of the produced composites was performed using XRD, FESEM, FTIR, TGA, and BET techniques. The XRD patterns of BG and La-BG show a good match with the combeite phase. The silicate and phosphate groups in the BG and La-BG lattice were detected in FTIR spectra. The BG particles were spherical, with a surface area of 11.54 m2 /g, a pore volume of 0.02491cc/g, and a pore size of 31.35Å. With the addition of La, the BG structure revealed (i) increased crystallinity of diffraction peaks, (ii) the particles changed from a spherical to a petal-like shape with an expansion in surface area and pore volume, and (iii) increased thermal stability of the BG structure. In conclusion, BG's physiochemical characteristics were greatly enhanced by adding La.

A comparative evaluation of light cure calcium silicate and resin-modified glass ionomer as indirect pulp capping agent in primary molars: A randomized clinical trial.

Minimally invasive techniques should be employed to maintain pulp vitality without affecting physiological tooth resorption for pediatric patients. This study aims to evaluate clinical and radiographic success of light cure calcium silicate and resin-modified glass ionomer (RMGI) as indirect pulp-capping agent in primary molars in children between 5 and 9 years. In this randomized clinical trial study, 40 primary molars with the International Caries Detection and Assessment System criteria 4-6 score were divided randomly into two groups after computerized randomization method. After caries excavation by minimally invasive dentistry principle, affected dentin was lined by either light cure calcium silicate (Group I) or RMGI (Group II) liner followed by composite restoration. Clinical success was determined with the absence of symptoms and bitewing radiographs were taken at baseline, 3, and 6 months' interval to measure increase in dentin increment using ImageJ software. Statistical analysis for intergroup comparison was done using Paired t-test, and Independent t-test was used for intragroup comparison. The level of statistical significance was set at P < 0.05. Change in dentin increment seen from baseline to 6 months in Group I was 0.19 mm and in Group II was 0.20 mm (P = 0.924). Intragroup increment was statistically significant during all follow-up intervals for both the groups (Group I - P ≤ 0.001, Group II - P = 0.009). For baseline remaining dentin thickness >1.5 mm, statistically significant increase was observed in the dentin increment at 3 months' interval between both the groups. Both TheraCal LC and Vitrebond show acceptable clinical and radiographic results when used in primary molars as indirect pulp treatment agents. Both the liners are equivalent to each other in terms of feasibility and cost-effectiveness but TheraCal LC can be preferred due to better handling and avoiding the manipulation step thereby reducing treatment time.