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The synthesis of zeolites from local resources has been an attractive route to address the demand for more economical means in the production of zeolites for commercial applications. In particular, Philippine bentonite -- a local clay material --has been used as a raw ingredient to synthesize zeolites, faujasite-type (FAU), and analcime-type (ANA) via hydrothermal synthesis. The silicon-aluminum ratio (SAR) and crystallization temperature were varied to investigate the conditions in the synthesis of pure FAU and ANA-type zeolites. X-ray diffraction allowed the identification of zeolite phases upon comparison to reference patterns from the International Zeolite Association database. The sample with the highest degree of crystallinity of 98% (ANA-type) was prepared at a temperature of 150 °C and an initial SAR of 1.18. This sample also exhibited the largest particle size of 29.1 µm in diameter. Scanning electron micrographs showed octahedral, spherical, and cross morphologies of the products, with average particle size ranging from 1.24 (± 0.13) to 29.1 (± 1.66) µm. The transformation of Philippine bentonite to different types of zeolites demonstrates the viability of local clays as raw resource material for hydrothermal synthesis of a wide range of zeolite frameworks. [ABSTRACT FROM AUTHOR]

This work presents a facile approach for controlling the optical and electrical parameters of a biopolymeric matrix for optoelectronics. Vanadium oxide (V2O5) and chromium oxide (Cr2O3) nanoparticles (NPs) were prepared and incorporated into the carboxymethylcellulose/polyethylene glycol (CMC/PEG) blend by simple chemical techniques. Transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD) data showed that V2O5 and Cr2O3 exhibited spherical shapes with sizes in the range of 40–50 nm and 10–20 nm, respectively. In addition, the blend's degree of crystallinity was sensitive to the V2O5 and Cr2O3 doping ratios. The scanning electron microscopy (FE-SEM) and the elemental chemical analysis (EDAX) used to study the filler distribution inside the blend, and confirmed the existence of both V and Cr in the matrix. Fourier transform infrared (FTIR) spectroscopy showed that the dopants significantly affected the blend reactive (C–O–C, OH, and C=O) groups. The stress–strain curves illustrated the reinforcing effect of the dopants up to 1.0 wt\% Cr2O3/V. The transmittance and absorption index spectra in the visible-IR wavelengths decreased with increasing filler content. Utilizing Tauc's relation and (optical) dielectric loss, the direct (indirect) band gap narrowed from 5.6 (4.5) eV to 4.7 (3.05) eV at 1.0 wt\% Cr2O3/V. All films have an index of refraction in the range of 1.93–2.17. AC conductivity was improved with increasing filler content and temperature. The energy density at 50 °C is in the range of 1–3 J/m3. The influence of V2O5 and Cr2O3 content on the optical conductivity, dielectric constant, loss, and dielectric modulus of CMC/PEG was reported. These enhancements in electrical and optical properties, along with the potential for band gap engineering, offer promising prospects for advanced applications in optoelectronics and energy-related fields. [ABSTRACT FROM AUTHOR]

Introduction: The microbial-induced restoration of ferruginous crusts (canga), which partially cover iron deposits and host unique ecosystems, is a promising alternative for reducing the environmental impacts of the iron mining industry. Methods: To investigate the potential of microbial action to accelerate the reduction and oxidation of iron in substrates rich in hematite and goethite, four different microbial treatments (water only as a control - W; culture medium only - MO; medium + microbial consortium - MI; medium + microbial consortium + soluble iron - MIC) were periodically applied to induce iron dissolution and subsequent precipitation. Except for W, all the treatments resulted in the formation of biocemented blocks. Results: MO and MI treatments resulted in significant goethite dissolution, followed by precipitation of iron oxyhydroxides and an iron sulfate phase, due to iron oxidation, in addition to the preservation of microfossils. In the MIC treatment, biofilms were identified, but with few mineralogical changes in the iron-rich particles, indicating less iron cycling compared to the MO or MI treatment. Regarding microbial diversity, iron-reducing families, such as Enterobacteriaceae, were found in all microbially treated substrates. Discussion: However, the presence of Bacillaceae indicates the importance of fermentative bacteria in accelerating the dissolution of iron minerals. The acceleration of iron cycling was also promoted by microorganisms that couple nitrate reduction with Fe(II) oxidation. These findings demonstrate a sustainable and streamlined opportunity for restoration in mining areas. [ABSTRACT FROM AUTHOR]

Using polyaspartic acid (PAsp) and bentonite (BT) as the main raw materials, a new type of degradable soil water retaining agent (PAsp-AA/BT) was synthesized by microwave radiation. The optimum synthesis conditions and comprehensive properties of PAsp-AA/BT were discussed and the structure and surface characteristics of PAspsp-AA/BT were characterized by FTIR, SEM, XRD and TGA in the paper. The results showed that the optimum synthesis conditions of PAsp-AA/BT were as follows: the dosages of polyaspartic acid (PAsp), bentonite (BT), initiator potassium persulfate, crosslinking agent N,N′-methylene bisacrylamide was 5, 3, 0.3, 0.03%, respectively, the neutralization degree of acrylic acid was 75%, and the microwave power was 490W. Under this condition, the absorption ratio of the synthesized PAspsp-AA/BT in deionized water and 0.9% NaCl solution was 953 and 164 g/g, respectively. The synthesized PAsp-AA/BT had a high water absorption rate, good water retention and repeated water absorption, and the degradation rate in soil within 30 days reached 32.75%, with good degradation effect. The analysis of SEM, FT-IR, XRD and TGA showed that: the surface of PAsp-AA/BT was rough and had obvious pore structure, which was conducive to the diffusion of water molecules; polyaspartic acid, bentonite and acrylic acid were polymerized; the cross-linking structure was formed between polyaspartic acid, bentonite and acrylic acid; the product of PASP-AA/BT had good thermal stability. This study provides a new soil water retaining agent, which is helpful for the better development of soil water retaining agent research. [ABSTRACT FROM AUTHOR]

The 2024-1.5 wt%CNTs@Ni (Nickel-coated carbon nanotubes) composite were subjected to equal channel angle pressing (ECAP) deformation treatment and the microstructure, hardness distribution and tensile properties were investigated and discussed. The quasi-in-situ corrosion observation and COMSOL corrosion simulation were used to analyze and reveal its corrosion behavior. The results showed that the stress and microstrain are mainly concentrated in the area near the inside corner, and the closer the inside corner, the finer the grain size and the more dispersed the second phase and CNTs@Ni. The average hardness of the ECAP-treated composite was about 136.54 HV, which was 44.41% higher than that of the as-cast composite (94.55 HV). The properties of the ECAP-treated composite were all higher than the as-cast composite, with the yield strength, tensile strength and elongation increasing to 283.49 MPa, 399.18 MPa and 11.69%, respectively, which were about 44.99%, 45.97% and 344.49% higher than the as-cast composite. The electrochemical properties of the ECAP-treated composite were better than the as-cast composite, with a corrosion current density of 88.319 μA∙cm2, which was 12.33% lower than that of the as-cast composite. The COMSOL simulation results indicated that the ECAP-treated composite required a longer time when the electrolyte was immersed to the same depth. [ABSTRACT FROM AUTHOR]

To realize the harmless treatment of various wastes and develop alternative fertilizers, fly ash and slags were soaked in waste acid liquid from desulfurization and denitrification to extract N, P, K, and other nutrient elements for fertilizer preparation. The experiments had shown that both slags with special porous structure and unburned biochar derived from biomass fly ash had good adsorption performance for crystalline salt, while the fine particles existing in biomass fly ash had significant agglomeration effects on crystalline salt. The coupling among the three substances above formed the multi-dimensional cross-scale structure carriers with sizes in the nanometer to millimeter range, which had good adsorption capacities for crystalline salt and effectively improved the slow-release performance of the self-prepared solid fertilizer. The microwave irradiation further enhanced the slow-release performance of the self-prepared solid fertilizer by promoting the coupling effects among various raw materials. Lastly, aiming the self-prepared solid fertilizer, the increments of plant height, leaf width, leaf length, and expansion diameter of chlorophytum were 5.10%, 77.19%, 47.37%, and 4.05%, respectively, higher than those with commercial solid fertilizer. These desirable slow-release characteristics and positive effects on chlorophytum growth highlighted the self-prepared fertilizer potential to improve plant growth. [ABSTRACT FROM AUTHOR]

The objective in this study was to use sandblasting waste (SW) and liquid crystal display waste glass (LWG) in the synthesis of eco-humidity control zeolite (E-HCZ) for use in the construction industry. Synthesis involved alkali fusion and hydrothermal processing, wherein the processing parameters ((SiO2)/(Al2O3) molar ratio, reaction temperature, reaction duration) were optimized using the reaction surface method in conjunction with Box–Behnken experiment design. An F value of 108.46 indicated the efficacy of the model. The important model terms included linear factors (A. (SiO2)/(Al2O3) molar ratio, B. reaction temperature, and C. reaction duration), square factors (A2, B2, and C2), and sympathetic factor AB. The model achieved a verification coefficient R2 of 0.9949, and the data obtained in experiments was consistent with the regression results. The adequacy of the regression model was confirmed by strong agreement between the predicted R2 (0.9149) and the adjusted R2 (0.9857), while the sufficiency of the signal was confirmed by a high signal-to-noise ratio (36.889). The results also indicate strong correspondence between actual vs. predicted probability plots. The high moisture adsorption capacity of the proposed zeolite (58.58 g/m2) demonstrates that LWG and SW can indeed be used to synthesize low-cost humidity control materials. [ABSTRACT FROM AUTHOR]

This study aimed to assess the efficacy of phototherapy with an Er, Cr:YSGG laser on the bond strength of dentin using two different adhesive systems after chlorhexidine (CHX) application. Twenty-four non-carious human molar teeth were separated into three main groups: negative control Group A (Group A), CHX and phototherapy with an Er, Cr:YSGG laser (Group PC), and CHX with conventional diamond bur (no phototherapy) (Group C). These groups were divided into two subgroups based on adhesives: Clearfil Universal Quick Bond and Clearfil SE Bond. To evaluate the microtensile bond strength, the occlusal enamel surfaces of the teeth were removed with a low-speed, water-cooled diamond bur to expose hard dentin tissue. The teeth within Group PC were treated with Er, Cr:YSGG phototherapy. The surfaces were then disinfected with 0.2% chlorhexidine gluconate. Subgroups were applied according to the manufacturer's instructions using the adhesive systems mentioned above. Following adhesive application, the teeth were restored with composite resin. A microtensile bond strength test was performed on the test sticks obtained from the teeth using a universal test device. Data were analyzed using variance analysis (ANOVA) at a significance level of p < 0.05. Among all groups, the highest bond strength was achieved with Clearfil SE Bond with CHX + phototherapy (45.6 ± 4.2), while the lowest was achieved with Clearfil Universal Quick Bond without phototherapy (control group) (27.0 ± 6.7) (p < 0.05). Phototherapy with Er, Cr: YSGG following chlorhexidine application enhanced the bond strength of both the bond systems (p < 0.05). [ABSTRACT FROM AUTHOR]

Objective: To evaluate the correlation between the dental crown's color and the pulse oximeter result in healthy teeth before and after 30 days of the end bleaching procedures. Material and methods: The dental crown's color of 70 healthy maxillary central incisors were evaluated using a spectrophotometer and the oxygen saturation level of the pulp was recorded using a pulse oximeter. The bleaching was performed using the combined technique, with 35% hydrogen peroxide bleaching gel, in the office stage, and 10% carbamide peroxide, in the at-home, for 16 days. The variables symmetry was verified by the Kolmogorov Smirnov test, and the quantitative variables described by mean and standard deviation. The correlation between quantitative variables was established using Pearson's correlation coefficient. The significance level considered was 5%. Results: A significant change was observed between values recorded by the pulse oximeter before (85.0% ± 4.1) and after (86.4% ± 2.3) 30 days of the end. Thirty days after the end of the bleaching procedures, the dental crowns were lighter with the difference between L*s equal to 1.4, more greenish with a difference between a*s equal to 1.3, and more bluish with a difference between b*s equal to -7.2. There was no correlation between the values of coordinates L*, a* and b* and the results recorded by the pulse oximeter in the initial period, respectively, or 30 days after the bleaching procedures, respectively. Conclusion: Changes in pulse oximeter recordings did not correlate with the change in the dental crown's color promoted by bleaching procedures. [ABSTRACT FROM AUTHOR]

Purpose: Riverine sediments are an important component of the aquatic environment as they play an essential role in influencing its eco-environmental functions. Sediments may serve as both the source and sink of heavy metals (HM). The Astore River basin is located in the Himalayas, northern Pakistan. The area is frequented by a high number of tourists and is characterized by a fragile biophysical system. This study aimed to assess the occurrence, spatial patterns, and potential sources of HM in the sediments of the Astore River network. Methods: Thirty-nine samples from the Astore River and its tributaries were collected and analyzed for nine HM (Fe, Mn, Cu, Zn, Cd, Cu, Co, Pb, and Ni) using atomic absorption spectrometry. Various modified indices, i.e., modified ecological risk index (mERI) and modified sediments pollution index (mSPI), were utilized to assess the sediment ecological and pollution risks. The data were subjected to compositional data analysis (Coda) using the R program for the source characterization of HM. Results: The results indicated that among the HM, Fe and Cd had the highest and lowest concentrations, respectively. Mn contributed the most to the pollution of the sediments, while Cd has the highest potential ecological impact. The mSPI indicated that the sediments were either in their natural state or showed low to moderate contamination, while only 2.5% were classified as extremely polluted. At the same time, 12.8% of the samples were categorized in the high pollution class. The ecological risk, however, showed more profound and negative bearings on the sediment quality as 33.3% and 2.5% of the samples showed considerable to high ecological risks. The spatial distribution of HM and the modified indices indicated Deosai valley as the zone of concern for management and abatement options. Conclusion: Overall, this study concluded that the major contribution to HM concentration in the area was from natural sources. However, in the case of Cd and Zn, an amplification in concentration due to anthropic factors was noted. Mn and Cd stood out as the major contaminants posing profound ecological risks. A differential spatial pattern of HM contamination in valleys suggested the need for targeted and specific management plans for prevention. [ABSTRACT FROM AUTHOR]

Electrolytic manganese residue (EMR) is a solid waste produced in the process of electrolytic manganese metal (EMM) production. In recent years, the accumulation of EMR has caused increasingly serious environmental problems. To better understand the state of EMR recycling in recent years, this paper used a comprehensive literature database to conduct a statistical analysis of EMR-related publications from 2010 to 2022 from two perspectives: harmless green treatment and resource utilization. The results showed that the research on the comprehensive utilization of EMR mainly focused on the fields of chemical hazard-free treatment and manufacturing building materials. The related studies of EMR in the fields of biological harmlessness, applied electric field harmlessness, manganese series materials, adsorbents, geopolymers, glass–ceramics, catalysts, and agriculture were also reported. Finally, we put forward some suggestions to solve the EMR problem, hoping that this work could provide a reference for the clean disposal and efficient utilization of EMR. [ABSTRACT FROM AUTHOR]

Aim: The study evaluated the influence of tucupi on enamel surface roughness, microhardness, ultramorphology, and mass variation. Materials and Methods: Ninety healthy bovine incisors were divided into three experimental groups, according to the acidic challenge adopted, being: G1- tucupi, G2- cola-based soft drink, G3-distilled water. The enamel properties (surface roughness, microhardness, ultramorphology and mass variation) of all specimens were evaluated at times T0 (before any intervention), T10 (10 days after the proposed treatments), T20 (20 days after the proposed treatments) and T30 (30 days after the proposed treatments). After confirming the normality of the data (Shapiro–Wilk test), a two-way ANOVA (α = 5%) was performed, followed by Sidak post-test, with results described as mean and standard deviation. Results: The roughness means increased for all tested groups, with no statistical difference only in G3 for all evaluated times. Microhardness of all groups showed a significant decrease over the time, with the lowest average observed in G1 in T30. Considering enamel mass variation, the lowest average was in G2 at time T3, with no statistical difference only in G3 (distilled water) over the time. Regarding ultramorphology (scanning electron microscopy – SEM), only groups G1 and G2, that were exposed to acidic challenges, showed disorganization of the enamel surface layer. Conclusion: It was possible to conclude that tucupi has low pH and high titratable total acidity, being able to gradually decrease enamel microhardness, increasing surface roughness and causing loss of dental enamel. [ABSTRACT FROM AUTHOR]

This work aimed to explore the effect of high pressures at room temperature on the vibrational modes and the thermal properties and stability of barium disilicate glass (BaO‐2SiO2) (BS2). The BS2 was prepared through the conventional melting route at atmospheric pressure. After being submitted to different pressure values (2.5 GPa, 4.0 GPa, and 7.7 GPa) and room temperature, the samples were characterized ex situ by Raman spectroscopy and differential thermal analysis. With this, it is possible to see that the pressure modifies the Raman vibrational modes of the glass, in the region associated with the Si‐O‐Si symmetrical bending modes. The Si‐O symmetrical stretching vibrational modes (Qn) remain unchanged, however there are changes on values of glass transition and decrease crystallization temperature, as well as the parameters of thermal stability of the glass. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to evaluate the remineralizing potential of prepared solutions of eggshell powder (ESP) and nano-hydroxyapatite (nHA) on the surface roughness and microhardness of bleached enamel. Materials and Methods: Fifty bovine anterior teeth were selected and cleaned then bleached using a chemically activated in-office bleaching agent then the teeth were randomly allocated into five groups (n = 10) according to the tested remineralizing agents (10% ESP solution, 10% nHA solution, and MI Paste Plus) into; control, bleached, bleached + ESP solution, bleached + nHA solution, and bleached + MI Paste Plus groups. Then, the teeth were tested for surface roughness and microhardness of the bleached enamel, respectively. Results: There was a statistically significant difference in the surface roughness and microhardness values of the tested groups. The highest surface roughness mean value was found in bleached enamel group, while the least mean value was found in the control group. The highest mean microhardness value was found in the bleached enamel + ESP solution group, while the least mean value was found in the bleached enamel group. Conclusions: The application of the tested remineralizing agents following the bleaching procedure had improved the surface roughness and microhardness of the bleached enamel. ESP and nHA present promising and potent remineralizing agents. [ABSTRACT FROM AUTHOR]

The low molecular weight organogels are interesting carriers for pharmaceutical compounds. However, their uses are limited due to the toxicity burden of the organic solvent used. Hence, this study aimed to prepare organogel using folic acid (FA) in different concentrations as a gelator for propylene glycol (PG) biocompatible solvent. The simple mixing method followed by incubation in a water bath at 90 °C was used to prepare organogels. Then, formulations were assessed using different methods including differential scanning calorimetry (DSC), dropping method, attenuated total reflectance – Fourier transform infrared spectroscopy (ATR-FTIR), oscillatory rheology studies, scanning electron microscopy (SEM), and in vitro dissolution study. Gel formation and its consistency were highly depending on FA concentration. The results showed that increasing the concentration of FA in the organogel led to accelerating the gelation process, and the least amount of FA that could gel the PG was 0.25% w/w. However, higher concentrations were needed to create an organogel with excellent properties. The DSC and dropping studies revealed stable organogels formulations at body temperature. The ATR-FTIR showed interactions between the pteridine ring of FA and PG. The strain amplitude and frequency sweep tests demonstrated an increase in storage modulus values as the concentration of FA increased at 37 °C, which were frequency independent at high frequencies. In addition, the SEM exposed the fabrics like the structure of these organogels. Furthermore, the in vitro dissolution of organogel was pH-dependent, with a high possibility of taking place in the large intestine. FA/PG organogel formulation is a promising carrier for drug and nutraceuticals compound for the oral delivery system. [ABSTRACT FROM AUTHOR]

High-grade calcium aluminate cement (CAC) has been successfully synthesized from municipal alumina waste and limestone under mild reaction conditions. Mineralogical composition and microstructure of the sintered mixes were investigated using X-ray diffraction and FESEM; valuable cementing phases such as CA, CA2, and C12A7 were observed in addition to the C3A phase that was detected in the mixes with high CaCO3 content. Mix CA60 containing 60 wt% alumina waste has achieved the best sinterability (less than 1 vol% porosity) and the highest densification (~ 2.65 g/cm3 bulk density) at 1450 °C. Densification, cold-crushing strength (CCS), and microstructure of the hydrated cement samples (From Mix CA60) were investigated. The cast cement specimens revealed better density and CCS characteristics (63.1 and 74 MPa at 7 and 28 days, respectively) in comparison with the commercial cement. Conventional castables (5 × 5 × 5 cm3) were prepared from mixtures composed of 15 wt% cement and 85 wt% aggregates (40% Al2O3), where CA60 and commercial cement were used to compare the effect of the manufactured CA60 cement with the commercial one. The castables prepared with CA60 cement have shown a higher strength at 110 °C with 4.5 MPa when compared to the commercial CAC at the same temperature (1.8 MPa). Accordingly, this study contributes not only to preserving the environment from the accumulation of industrial wastes but also to valorizing and adding value to these wastes. [ABSTRACT FROM AUTHOR]

The kinetics and mechanism of the development of nepheline (NaAlSiO4) through thermal transformation of sodalite (Na4Al3Si3O12Cl) was studied by means of differential thermal analysis at different heating rates (10°C min−1 to 50°C min−1) to control the evolution of the crystallization fraction. The conversion of sodalite (cubic crystal) to pure nepheline (hexagonal crystal) took place in the 800°C–900°C interval. The activation energy for nepheline crystallization from sodalite was determined by isothermal and non‐isothermal methods. The ratio t0.75/t0.25, together with the Avrami exponent (n) and the numerical factor of the dimensionality of crystal growth (m) parameters indicated that dominant crystallization mechanism in nepheline development is bulk crystallization mechanism controlled by interface reaction. [ABSTRACT FROM AUTHOR]

The present study attempts to investigate physicochemical features and evaluate quality of collected ground water samples from benchmark locations in Fazilka district, southwestern (SW) side of the Punjab. The samples of groundwater (GW) as well as soil were collected from different locations and examined for pH, electrical conductivity (EC), carbonates (CO32), bicarbonates (HCO3−), chlorides (Cl−), magnesium (Mg2+), calcium (Ca2+), sodium (Na+), sulfate (SO42−) and potassium (K+). The appropriateness of water for drinking was checked using water quality index (WQI), while indices like soluble sodium percentage (SSP), sodium adsorption ratio (SAR), residual sodium carbonate, magnesium hazard, permeability index and Kelly's ratio were investigated for appraisal of irrigation water quality. Samples are statistically tested using two-way ANOVA and principal component analysis (PCA) to extract correlation between water parameters. Most of the samples were under high to low (C3S1), high to medium (C3S2) and very high to high (C4S3) based on US Salinity Laboratory (USSL). On the base of RSC, samples were under safe to unsuitable category. For hydrochemistry analysis, the piper diagram indicates that water samples were mixed type and Ca-Mg-HCO3 type. Study indicated that water with high salinity was used for irrigation of crops and it has adverse effects on the soil quality and crop yield is of concern for future. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this in situ study was to evaluate different dentifrices on enamel after bleaching under normal and hyposalivatory conditions. Materials and methods: Twenty-four participants were assigned of which 12 had normal and 12 had low salivary flow. The study was conducted in 6 in situ experimental phases of 24 h duration: placebo, NaF, SnF2, F/Sn/Chitosan, F/Arginine, and F/Bioactive Glass. The specimens were previously bleached in vitro. Microhardness (SMH), roughness (Ra), and color analyses (CIELAB and ΔE00) were performed at baseline (T1), after bleaching (T2) and after in situ phase (T3). Scanning electron microscopy (SEM) and the elemental levels (wt%) of Ca, P, and Na and the proportion between Ca and P were determined using an energy-dispersive X-ray spectrometer (EDS) in T3. The SMH and Ra were analyzed by mixed models for repeated measures and Tukey Kramer. The color and Na% were analyzed by split-plot ANOVA and Tukey test. The EDS were analyzed by Mann's Whitney nonparametric, Friedman, and Nemenyi tests (p<0.05). Results: The dentifrices placebo and NaF in the low flow presented lower SMH and higher Ra in T3 and lower Ca% compared to the same dentifrices in normal flow. For normal flow, SnF2 resulted in greater SMH. For low flow, SnF2, F/Sn/Chitosan, and F/Bioactive Glass resulted in higher SMH in T3 and did not differ from T1. F/Bioactive Glass showed lower Ra among the dentifrices evaluated for both salivary flows, whereas SnF2 showed the highest. F/Bioactive Glass showed a statistically significant difference from placebo for Ca%, P%, Na%. For ΔE*ab and ΔE00 (T1×T3), no differences were found for the dentifrices and salivary flows. Conclusion: The low salivary flow had less capacity for remineralization of bleached enamel compared to normal flow. Overall, the dentifrice with bioactive glass had the best performance in bleached enamel under low and normal salivary flow condition. Clinical relevance: It is recommended to use a bioactive glass-based dentifrice after bleaching to promote tooth enamel recovery for patients with or without impaired salivary flow. [ABSTRACT FROM AUTHOR]

A series of CeO2 nanoparticles was synthesized by precipitation in reverse microemulsions in the presence of mixed aqueous–alcoholic solutions at variable and constant medium pH. It is shown that these methods promote the formation of non-agglomerated CeO2 particles with a size less than 15 nm. TEM and XPS methods showed that the ratio of Ce3+ /Ce4+ ions increases on the surface when the size of CeO2 nanoparticles is decreased. The synthesized CeO2 nanoparticles show high stability in aqueous suspensions without using additional stabilizers (휁 > +35 mV), which is important for medical and biological application. [ABSTRACT FROM AUTHOR]

Retrofitting thermal insulation to solid masonry walls alters their hygrothermal behaviour, which can be modelled by hygrothermal simulation software. However, such software needs values of key material properties to ensure satisfactory results and until now data has not been available for Scottish masonry buildings. This work aims to contribute to a Scotland-specific dataset of material properties for use by designers working on such buildings. Thermal conductivity, water vapour permeability, sorptivity, water absorption coefficient, hygroscopic sorption, density and porosity were all determined experimentally for selected historic and contemporary masonry materials. Within the range of materials tested three groups of materials properties emerge. Natural hydraulic lime mortars, hot-mixed quicklime mortar and earth mortar all show comparatively low density, high porosity, low thermal conductivity, high water vapour permeability and variable but generally high hygroscopic sorption. Craigleith, Hailes and Giffnock sandstones, no longer available but obtained from conservation works on historic buildings, and Locharbriggs and Hazeldean sandstones, obtained from current production, all show intermediate values of these properties. Crathes granodiorite and Scottish whinstone (from current production) show high density, low porosity, high thermal conductivity, low water vapour permeability and low hygroscopic sorption. It is shown that these materials are all relevant to Scottish buildings constructed in traditional masonry and this paper presents the first comprehensive set of hygrothermal property data for them. [ABSTRACT FROM AUTHOR]

Analcime is nowadays an important component in dental porcelain systems, in heterogeneous catalysis, in the nanoelectronic field, in selective adsorption and in stomatology (dental filling and prosthesis). Analcime synthesis from an impure, silica-rich kaolinite rock coming from Romana (Sassari, Italy) is here presented. A synthesis protocol is proposed that aims to make an improvement of synthesis conditions compared to the past. The hydrothermal treatment is in fact here achieved without aging times and without the use of sodium silicate or other additional silica source reported in the literature. Lower calcination temperature, synthesis temperature and crystallization time are verified in this work. The kaolin is subjected to calcination at the temperature of 650 °C and then mixed with NaOH. The experiment is performed at ambient pressure and 170 ± 0.1 °C. The degree of purity of analcime is calculated in 97.57% at 10 h. Analcime is characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, inductively coupled plasma optical emission spectrometry and thermal analysis. Density is also calculated. Cell parameters and the amount of amorphous phase in the synthesis powders is estimated with quantitative phase analysis using the combined Rietveld and reference intensity ratio methods. The experimental conditions make the synthesis protocol particularly attractive from an economic point of view. Also this work does not use a commercial kaolin but silica-rich impure kaolinitic rock from a disused quarry. This further reduces the costs of the experimental protocol. It also gives the protocol an added value, as the synthesis of a useful mineral is obtained through the valorization of an otherwise unused georesource. Both chemical and physical characterization of analcime is satisfactory making the experimental protocol very promising for an industrial transfer. [ABSTRACT FROM AUTHOR]

In order to conserve natural resources and prevent waste generation, effective utilization of industrial wastes and/or by-products for beneficial engineering applications becomes inevitable. In order to accomplish this, extensive research studies, exploring properties and new applications of waste materials in a sustainable and environmentally friendly manner, have been initiated worldwide. Red mud (RM, also known as bauxite residue) is one of the wastes generated by the aluminium industry and its disposal and utilization have been traditionally hindered due to the extreme alkalinity (pH about 10.5–13.5). To date, no comprehensive review on various properties of RM of different origin and associated challenges in using it as a beneficial engineering material has been performed. The objective of this study is first to critically appraise the current understanding of properties of RM through a comprehensive literature review and detailed laboratory investigations conducted on Indian RM by the authors, to assess and identify the potential engineering applications, and to finally discuss associated challenges in using it in practical applications. Physical, chemical, mineralogical and geotechnical properties of RMs of different origin and production processes are reviewed. Mechanisms behind the pozzolanic reaction of RM under different chemical and mineralogical compositional conditions are discussed. Environmental concerns associated with the use of RM are also raised. Studies relevant to leachability characteristics reveal that most of the measured chemical concentrations are within the permissible regulatory limits. Overall, the review shows that RM disposal and reuse is complicated by its extreme alkalinity, which is also noticed to be influencing multiple engineering properties. But with selected pH amendments, the treated RM is found to have significant potential to be used as an effective and sustainable geomaterial. The assessment is majorly based on the characteristics of Indian RMs; hence the adaptation of the findings to other RMs should be assessed on a case-by-case basis. Moreover, field studies demonstrating the performance of RM in various engineering applications are warranted. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the bleaching effectiveness and mineral alterations following the use of experimental bleaching gels that included 6% hydrogen peroxide (HP), titanium dioxide (TiO2) and/or chitosan in comparison with the routinely used 35% HP bleaching gel. Thirty-six maxillary anterior teeth were divided into three groups according to bleaching agent as follows: Group 1: 6% HP + TiO2, Group 2: 6% HP + TiO2 + chitosan, Group 3: 35% HP. Tooth colour was measured with a spectrophotometer before bleaching and after sessions one and two on days 14 and 30, respectively. Colour changes were assessed with the CIEDE2000 and CIELab formulas. Mineral analysis was performed with a scanning electron microscopy–energy dispersive X-ray (SEM–EDX) device before and 14 days after application. The enamel surfaces of randomly selected samples from each group were analysed by SEM. Two-way ANOVA was used to compare differences between groups. All tested materials resulted in significantly increased bleaching compared to the initial colour values (p < 0.05). Group 3 showed significantly more whitening compared to the other groups after the first and second sessions (p < 0.05). However, Group 2 presented prolonged whitening efficiency and reached a bleaching level similar to the 35% HP treatment after 14 and 30 days. The results of the CIEDE2000 and CIELab formulas were found to be correlated (r > 0.6). The increases in Ca were similar in Groups 2 and 3 (p > 0.05) and were significantly higher than that in Group 1 (p < 0.05). p was similarly decreased among all groups (p > 0.05). The combination of 6% HP, chitosan and TiO2 appears to constitute a promising material for tooth whitening, showing good bleaching efficiency and acceptable mineral alterations. [ABSTRACT FROM AUTHOR]

Background: Tooth whitening is one of the most requested dental treatments, but it still presents some side effects. Indeed, the bleaching agent can generate patients' discomfort and dental hard tissue damages, not achieving an efficient and long-lasting treatment with optimum whitening effect. To overcome these limitations, the bleaching agents containing nano-hydroxyapatite can represent a reliable solution to avoid these detrimental effects. Methods: In this study, human third molars were treated with commercial bleaching agents, containing nano-hydroxyapatite (nHA) and 6% (at-home treatment), 12% and 18% (in-office treatments) of hydrogen peroxide (HP), named respectively G1, G2 and G3. The results were evaluated descriptively and analytically using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATRFTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDS), comparing the treated groups with a commercial gel containing 10% carbamide peroxide (CONV) and with a non-treated control group (CTRL). Results: ATR-FTIR analysis revealed a similar composition in carbonates and phosphates for CTRL, G1 and G2 groups, which showed no significant differences in their spectral profiles; an increased amount of organic matter was found in G3, while CONV displayed an intermediate behavior. SEM analysis did not highlight significant changes in the enamel microstructure of G1 and CONV when compared to CTRL; the pattern observed in G2 presented a slight increase of enamel irregularities, while G3 displayed a partial removal of the aprismatic layer and microporosities. No evident effects due to nHA were observed in the structure of the hydroxyapatite component of G1, G2 and CONV, if compared to CTRL, while G3 showed a slight loss of crystallinity. In all groups, EDS identified slight changes in the concentration of chemical elements O and Ca, while the Ca/P ratio was similar when compared to CTRL. Conclusion: The obtained results suggest that the application of the tested commercial bleaching agents, with a concentration of HP up to 12%, does not alter the morphological and chemical composition of the enamel surface and maintains its crystallinity. [ABSTRACT FROM AUTHOR]

The main goal of this work was to demonstrate a broad range of starch applications in ceramic powder synthesis, and to point out that starch and its derivatives can successfully replace polyvinyl derivatives commonly used in ceramic formulations, as they are water-soluble saccharides, burn out more easily, reduce the exothermicity of the combustion reaction, and allow to receive fine and uniform ceramic powders. Starch is an eco-friendly and easily transformable natural carbohydrate polymer that is found in a variety of applications in ceramics and materials science. In this paper, we review the influence of starch on the physicochemical properties of the ceramic powders obtained by means of various synthesis methods (sol–gel method, combustion process, combined methods, and hydrothermal synthesis). Starch plays a differentiated role in each of these methods, i.e., it is a polymerizing agent in sol–gel method, a fuel in combustion process, and a substrate for carbon spheres in hydrothermal synthesis. Highlights: Starch can replace polyvinyl derivatives used in ceramic formulations. Starch helps to control particle size of the powders and prevents agglomeration. Starch helps to create a more compact and porous structure in the sol–gel method. Starch is a highly energetic fuel that provides energy during combustion. [ABSTRACT FROM AUTHOR]

The occurrence and bioaccessibility of potentially toxic elements (PTEs) in soils and sediments are investigated by many studies, especially in territories exploited by mining and ore-processing activities, nearby agriculture-driven rural cities. Accordingly, the present study aimed at evaluating the geochemical properties, potential bioavailability, and risks for environment and human health of the most concerning PTEs of study area (Gafsa mining basin, Tunisia) such as Cd, Cr, and Zn in selected soil, sediment, and mining waste samples. The extraction of these solid matrixes by modified EU-BCR sequential extraction revealed that the most easily extractable fractions of each PTE were very low (first 2 steps, < 10%), Cd was mainly associated with the oxidizable phase (likely organic matter), and Cr and Zn were mostly found in residual mineral fraction (likely occluded in non-siliceous mineral phase). The total cumulative concentration of each metal was found to be higher in soil/sediment profiles and ore-processing wastes than in phosphate rocks, indicating a metal enrichment due to mining activities. The aqua regia extraction of representative sediment samples revealed that Cd, Cr, and Zn concentrations were higher than non-polluted sediment standards. In contrast, other elements as Cu, Mn, and Pb essentially arose from natural bedrocks. The Unified BARGE method was applied to assess the risk of ingestion by human beings and wild/domestic animals of contaminated sediment particulate prone to wind erosion and air dispersion in the arid conditions of study area. An higher oral bioaccessibility was found for Cd than Zn and Cr, most concerning in acid gastric phase than in sub-neutral intestinal environment. [ABSTRACT FROM AUTHOR]

The Ni-doped Ca2Al2SiO7 glass systems were prepared by flame synthesis. Solid-state reaction was used to prepare the powder precursors. The concentration of Ni was 0.5, 1 and 3 mol%. Polydisperse systems were prepared with diameters between 5 and 140 μm. Detailed examination of morphology of the glass microbeads by SEM revealed no features indicating the presence of crystalline phases. However, X-ray diffraction analysis showed that the samples GNi0.5 (0.5 mol% of Ni) and GNi1.0 (1.0 mol% of Ni) contained traces of crystalline gehlenite. HT-XRD was used to determine the temperature dependence of phase composition. For all prepared compositions, only one crystalline phase (Ca2Al2SiO7) was observed. DSC measurements in the temperature range 30–1200 °C at five different heating rates were carried out to study the thermal behavior. The DSC curves of all glasses contained one exothermic peak, which was attributed to crystallization of the gehlenite. The maximum of the peak decreased with increasing Ni content in the microspheres. The kinetic parameters (frequency factor A, apparent activation energy Eapp and the Avrami coefficient m) of the crystallization were determined using the Johnson–Mehl–Avrami–Kolgomorov model. In case of GNi0.5 and GNi1.0 glasses, the nucleation's rate had linear temperature dependence, the crystal growth interface is controlled by chemical boundary and the crystal growth is one-dimensional. The rate of nucleation is linear, the crystal interface growth is controlled by diffusion and one-dimensional crystal growth prevails in crystallization of the GNi3.0 (3.0 mol% of Ni). [ABSTRACT FROM AUTHOR]

The natural layered clay-based materials offer a sustainable approach for removal of emerging pollutants from the environment. Their low-capacity and poor-selectivity for pollutants often limit their uses. This limitation is addressed in this study with the help of Al-oxide pillaring approach. Here microporous aluminum-pillared clay (Al-PILC) was prepared from locally available Smectite clay (montmorillonite, MMT), by intercalation of Al-oxide pillars into the interlayer structure. The method increased the surface area of natural clay to 258 m2 g−1 and its porosity to 0.16 cm3 g−1. The adsorptive removal properties of prepared Al-PILC was evaluated on two selected pharmaceuticals and personal care products (PPCPs) viz. amoxicillin (AMOX) and imipramine (IMP). The results of the removal of these PPCPs were compared as a function of contact time (0–180 min), solution pH (2–12), initial concentration (0–100 mg L−1), and temperature (298–318 K). The Al-PILC adsorbs 332% more IMP and 681% more AMOX as compared to natural clay, and the maximum adsorption amounts on Al-PILC follows the order IMP > AMOX with 59.8 and 7.7 mg g−1, respectively. The kinetics of adsorption of both AMOX and IMP follow pseudo-second-order model, with intraparticle diffusion as rate-determining step. The incorporated acidic sites in clay (in form of Al2O3 pillars) enhanced its adsorption properties. These sites interacted with protonated amine and –OH groups of AMOX and the tertiary amine group of IMP. The Al-PILC exhibit effective regeneration and was reused up to three consecutive adsorption/desorption cycles. All in all, this study is expected to expand the application of Al-PILC on the adsorptive removal of the emerging pollutant from contaminated water. [ABSTRACT FROM AUTHOR]

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Abstract: Sediments serve as an indicator of the state of the environment, as they reveal, anthropogenic influences (e.g. industry) over time. The knowledge about the composition of sediments, in particular by the speciation, helps in the assessment of the environmental situation. The speciation of mercury in sediments is still being discussed and continues to pose a great challenge for analytical chemists. Despite a broad number of publications in this area, there is no gold-standard about the speciation of mercury in sediments. The reason for this is the growing interest in new, better methods for the speciation of mercury, which increases the number of publications and the uncertainty among the analysts. Therefore, the methodology of mercury speciation in sediments requires improvement and would benefit from a standardized approach. The goal of this review is to give an overview of the existing methods and to discuss the issues of methodology. Discussed parts in this review article include: (1) available reference material, (2) the methodology of extraction, (3) enrichment procedures, (4) separation and (5) detection.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Interactions of arsenic with essential trace elements may result in disturbances on body homeostasis. In the present study, we aimed to investigate the effects of different arsenic compounds on micromineral content and antioxidant enzyme activities in rat liver. Male Wistar rats were randomly divided into five groups and exposed to sodium arsenite and sodium arsenate at 0.01 and 10 mg/L for 8 weeks in drinking water. The concentration of arsenic increased in the liver of all arsenic-exposed animals. The proportion of zinc and copper increased in animals exposed to 0.01 mg/L sodium arsenite. In addition, these animals presented a reduction in magnesium and sodium content. Superoxide dismutase activity decreased mainly in arsenite-exposed animals, whereas catalase activity decreased in animals exposed to 10 mg/L sodium arsenate. Further, exposure to sodium arsenate at 10 mg/L altered copper and magnesium content in the liver, and reduced total protein levels. Overall, both arsenic compounds altered the liver histology, with reduction in the proportion of cytoplasm and hepatocyte, and increased the percentage of sinusoidal capillaries and macrophages. In conclusion, our findings showed that oral exposure to arsenic compounds disturbs the trace elements balance in the liver, especially at low concentration, altering enzymatic and stereological parameters. We concluded that despite the increase in trace elements content, the antioxidant enzyme activities were downregulated and did not prevent morphological alterations in the liver of animals exposed to both arsenic compounds. [ABSTRACT FROM AUTHOR]

Gamma-ray irradiation assisted polyacrylamide gel route was used to prepare CoAl2O4 nanoblue pigments. In this route, citric acid was used as a carboxyl and hydroxyl type chelating agent. The phase purity, morphology, and optical and fluorescence properties of as-prepared samples were analyzed via X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometer, transmission electron microscopy (TEM), UV-Visible spectrophotometer, and a confocal Raman system. XRD analysis indicates that the xerogel sintered at relatively low temperature (500 °C) to obtain single phase CoAl2O4 nanopowders. The primary crystal of CoAl2O4 nanoblue pigment is only 28 nm characterized by TEM, which is more likely to be realized with high uniformity than that the CoAl2O4 nanopowders prepared by conventional polyacrylamide gel route. Optical properties of CoAl2O4 nanoblue pigment shows that the optical energy gap (Eg) of nanoblue pigment increases with the decrease of crystallite size. The CIE parameter of CoAl2O4 nanoblue pigment indicates that a different sintering temperature causes a variation in the color of nanoparticles. The fluorescence spectra show that a major blue emission band around 400 nm and a weaker side band located at 430 nm are observed when the excitation wavelength is 325 nm. The chelation mechanism and fluorescence mechanism of the CoAl2O4 nanoblue pigment have been analyzed based on the experimental results.A cubic nano-CoAl2O4 pigments were synthesized by γ-ray irradiation assisted polyacrylamide gel route. The nano-CoAl2O4 pigments with high uniformity than that the CoAl2O4 nanopowders prepared by conventional polyacrylamide gel route. The SAED pattern revealed that the CoAl2O4 nanoparticles possess interplanar spacing of 2.8651, 2.4434, 2.0258, 1.5586, 1.4327, 1.3657, and 1.1549 Å corresponding to the (220), (311), (400), (511), (440), (531), and (444) planes, respectively. The UV-Vis absorption spectrum shows three obvious absorption peaks at 551, 590, and 628 nm and the CIE parameter is consistent with the real photos. [ABSTRACT FROM AUTHOR]

Geometric and electronic properties of 3,4-ethylenedioxythiophene (EDOT), styrene sulfonate (SS), and EDOT: SS oligomers up to 10 repeating units were studied by the self-consistent charge density functional tight-binding (SCC-DFTB) method. An application of PEDOT:PSS for ammonia (NH) detection was highlighted and investigated both experimentally and theoretically. The results showed an important role of H-bonds in EDOT:SS oligomers complex conformation. Electrical conductivity of EDOT increased with increasing oligomers and doping SS due to enhancement of π conjugation. Printed PEDOT:PSS gas sensor exhibited relatively high response and selectivity to NH. The SCC-DFTB calculation suggested domination of direct charge transfer process in changing of PEDOT:PSS conductivity upon NH exposure at room temperature. The NH molecules preferred to bind with PEDOT:PSS via physisorption. The most favorable adsorption site for PEDOT:PSS-NH interaction was found to be at the nitrogen atom of NH and hydrogen atoms of SS with an average optimal binding distance of 2.00 Å. [ABSTRACT FROM AUTHOR]

There is growing global interest in maximising the re-use and recycling of waste, to minimise the environmental impacts associated with waste treatment and disposal. Use of high-volume wastes in the production of blended or novel cements (including alkali-activated cements) is well known as a key pathway by which these wastes can be re-used. This paper presents a critical overview of the urban, agricultural, mining and industrial wastes that have been identified as potential precursors for the production of alkali-activated cement materials, or that can be effectively stabilised/solidified via alkali activation, to assure their safe disposal. The central aim of this review is to elucidate the potential advantages and pitfalls associated with the application of alkali-activation technology to a wide variety of wastes that have been claimed to be suitable for the production of construction materials. A brief overview of the generation and characteristics of each waste is reported, accompanied by identification of opportunities for the use of alkali-activation technology for their valorisation and/or management. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Policy-making in social-ecological systems increasingly looks to iterative, evolutionary approaches that can address the inherent complexity of interactions between human wellbeing, provision of goods, and the maintenance of ecosystem services. Here, we show how the analysis of available time-series in tropical delta regions over past decades can provide important insight into the social-ecological system dynamics in deltaic regions. The paper provides an exploratory analysis of the recent changes that have occurred in the major elements of three tropical deltaic social-ecological systems, such as demography, economy, health, climate, food, and water. Time-series data from official statistics, monitoring programmes, and Earth observation data are analysed to explore possible trends, slow and fast variables, and observed drivers of change in the Amazon, Ganges-Brahmaputra-Meghna and Mekong deltas. In the Ganges-Brahmaputra-Meghna delta zone, increasing gross domestic product and per capita income levels since the 1980s mirror rising levels of food and inland fish production. In contrast, non-food ecosystem services, such as water availability, water quality, and land stability appear to be deteriorating. In the Amazon delta, natural and anthropogenic perturbations are continuously degrading key ecosystem services, such as carbon storage in biomass and soils, the regulation of water balance, and the modulation of regional climate patterns. In the Mekong delta, rapid economic development, changing land-use practices, and salinity intrusion are progressively putting more pressure on the delivery of important provisioning services, such as rice and inland aquaculture production, which are key sources of staple food, farm incomes, and export revenue. Observed changes in many key indicators of ecosystem services point to a changing dynamic state and increased probability of systemic threshold transformations in the near future. [ABSTRACT FROM AUTHOR]

The main source of environmental arsenic exposure in most countries of the world is drinking water in which inorganic forms of arsenic predominate. The present study was aimed to test the impact of two different compounds of inorganic arsenic in histomorphometric and enzymatic parameters in the testes by oral exposition. Adult Wistar male rats were exposed to sodium arsenite and arsenate in drinking water, testing for each chemical form the concentrations of 0.01 and 10 mg/L per 56 days. The animals intoxicated with arsenic, mainly sodium arsenite, showed reduction in the percentage of seminiferous epithelium and in proportion and volume of Leydig cells. Moreover, there was an increase in the percentage of tunica propria, lumen, lymphatic space, blood vessels, and macrophages. The activity of superoxide dismutase (SOD) did not change among the groups. However, the activity of catalase (CAT) decreased in animals exposed to both arsenic compounds. In addition, the higher concentration of arsenic, mainly as sodium arsenite, caused vacuolization in the seminiferous epithelium. The body and testes weight as well as testosterone concentration remained unchanged among the groups. In conclusion, exposition to arsenic, mainly as sodium arsenite, caused alteration in histomorphometric parameters and antioxidant defense system in the testes. [ABSTRACT FROM AUTHOR]

This study focuses on the thermoformability of biopolymer films derived from corn starch and filled with montmorillonite-based nanoclay fillers. Biopolymer films with nanoclay concentrations from 0 to 5 wt% were prepared by solution casting and followed by thermoforming. The result shows that nanoclay addition improves the formability (dimensional stability and plugging property) of thermoformed specimen and also depends on the nanocomposite structure and clay concentration. Improved product stability with optimized properties was observed at 2–3 wt% nanoclay concentration due to exfoliated structure and better nanoclay particle dispersion in the polymeric matrix. Thermogravimetric analysis and dynamic mechanical analysis show maximum of 27℃ increased decomposition temperature, 12% increased storage modulus and 4℃ increased Tg at 5 wt% nanoclay-filled biopolymer film. Tensile result shows 13% increased strength, two-fold increased modulus and 29% reduced elongation for 3 wt% nanoclay-filled biopolymer series. [ABSTRACT FROM AUTHOR]

The esterification reaction between glycerol and lauric acid was conducted in the presence of commercial Amberlyst IR-120 and synthesized silicotungstic acid (STA)/SBA-15 at 393, 413 and 433 K. The results indicated that STA/SBA-15 was more convenient than Amberlyst IR-120 by means of monoglyceride production. Higher selectivity to monoglyceride obtained in the presence of STA/SBA-15 was due to its mesoporous structure, which induced shape selectivity in favor of monoglyceride. Reaction experiments in the presence of recovered catalysts showed an increase of monoglyceride selectivity, which was due to adsorbed lauric acid inside the mesopores. The selectivity was shown to be altered towards monoglyceride by simply changing the feed ratio and applying washing procedure on the catalyst. Characterization studies conducted on recovered catalysts validated the preservation of catalyst structure and the stability of the catalyst even after utilization for 7 days. [ABSTRACT FROM AUTHOR]

Gold mining is known to generate important economic products but also to produce several types of contamination/pollution. We report here the first data about Hg concentrations in the soils of the Yacuambi River in the Ecuadorian Amazon. We analyzed soil samples to assess the extent of contamination caused by gold placer mining in this area. Hg concentrations in soils exceeded the local background concentrations. High concentrations of Mn, As, Pb, Cr, Cu, Fe and Zn in some soil samples were probably derived from the geology of the site, which is rich in polysulfides and metamorphic rocks. Placer mining may accelerate the natural release of these elements to the environment by the exposure of the bedrock to the atmosphere. Accumulation of Hg in the river soils may be a potential source of toxicity for aquatic life and a risk to human health in the future. [ABSTRACT FROM AUTHOR]

After the detection of arsenic (As) toxicity in sheep from Ebrahim-abad and Babanazar villages in Kurdistan province, the concentration of this element in drinking water, cultivated soil, alfalfa hay, wool, and blood samples was evaluated. Total As concentrations ranged from 119 to 310 μg/L in drinking water, 46.70-819.20 mg/kg in soil 1.90-6.90 mg/kg in vegetation 1.56-10.79 mg/kg in sheep's wool, and 86.30-656 μg/L in blood samples. These very high As contents, in all parts of the biogeochemical cycle, exceed the recommended normal range for this element compared with a control area. Results indicate that As has moved through all compartments of the biogeochemical cycle by way of direct or indirect pathways. The present investigation illustrated decreased packed cell volume and hemoglobin in sheep from the As-contaminated zone. It was concluded that sheep from the contaminated areas suffer from anemia. Chronic As exposure of the liver was determined by liver function tests. For this purpose, blood aspartate transaminase (AST) and alanine transaminase (ALT) were measured. The results show that serum ALT and AST activities are increased significantly ( p < 0.01) in the sheep population exposed to As in the contaminated zone. Moreover, chronic As exposure causes injury to hepatocytes and damages the liver. [ABSTRACT FROM AUTHOR]

The problems with non-degradable materials in different applications have led to an interest in materials based on bionanocomposites. In this study, polymer-montmorillonite nanocomposites based on natural polymers (chitosan, alginate, gelatin and starch) and montmorillonite (MMT) were prepared using solution intercalation method. Then hybrid nanocomposites were synthesized by chemical oxidative polymerization of aniline in the presence of polymer-MMT nanocomposites. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) were employed to characterize the nanocomposites. FT-IR confirmed the successful preparation of hybrid nanocomposites. From the XRD results, intercalation of the MMT platelets in the matrix of polymers was examined. Further investigation by TEM images showed a mixed intercalated and flocculated structure for nanocomposites. Moreover, the TGA results showed improved thermal stability for the nanocomposites. The results presented in this study showed the feasibility of using these hybrid nanocomposites with improved properties in wide range of applications. [ABSTRACT FROM AUTHOR]

Following the appearance of symptoms of arsenic toxicity in the inhabitants of villages in the Muteh gold mining region, central Iran, the concentration of this element in various parts of biogeochemical cycle is investigated. For this purpose, rock, groundwater, soil, plant, livestock hair and wool, and human hair samples are collected and analysed. Total arsenic content ranges from 23 to 2,500 mg/kg in rock samples, 7-1,061 μg/l in water, 12-232 mg/kg in soil, 0.5-16 mg/kg in plant samples, 4.10-5.69 mg/kg in livestock hair and wool, and 0.64-5.82 mg/kg in human hair. Arsenic concentration in various parts of biogeochemical cycle near the gold deposit in a metamorphic complex, and also close to the gold-processing plant, is very high and decreases exponentially with increasing distance from them. Arsenic concentration in water from a well close to the Muteh gold mine is above 1 mg/L. Arsenic in hair samples taken from local inhabitants is above the recommended levels, and the control samples in Shahre-Kord city. Arsenic concentration is higher in male population and correlates positively with age. It is suggested that arsenic resulting from the decomposition of ore mineral such as orpiment (AsS), realgar (AsS) and arsenopyrite (FeAsS) is responsible for polluting natural resources and the human intake via drinking water and the food chain. Gold mining and processing has undoubtedly enhanced the release of arsenic and intensified the observed adverse effects in Muteh area. [ABSTRACT FROM AUTHOR]

In vivo estimations of Pb particle bioavailability are costly and variable, because of the nature of animal assays. The most feasible alternative for increasing the number of investigations carried out on Pb particle bioavailability is in vitro testing. This testing method requires calibration using in vivo data on an adapted animal model, so that the results will be valid for childhood exposure assessment. Also, the test results must be reproducible within and between laboratories. The Relative Bioaccessibility Leaching Procedure, which is calibrated with in vivo data on soils, presents the highest degree of validation and simplicity. This method could be applied to Pb particles, including those in paint and dust, and those in drinking water systems, which although relevant, have been poorly investigated up to now for childhood exposure assessment. [ABSTRACT FROM AUTHOR]

This review discusses and summarizes the latest reports regarding the agronomic utilization and potential environmental effects of different types of phosphate (P) fertilizers that vary in solubility. The agronomic effectiveness of P fertilizer can be influenced by the following factors: (1) water and citrate solubility; (2) chemical composition of solid water-soluble P (WSP) fertilizers; (3) fluid and solid forms of WSP fertilizers; and (4) chemical reactions of P fertilizers in soils. Non-conventional P fertilizers are compared with WSP fertilizers in terms of P use efficiency in crop production. Non-conventional P fertilizers include directly applied phosphate rock (PR), partially acidulated PR (PAPR), and compacted mixtures of PR and WSP. The potential impacts of the use of P fertilizers from both conventional (fully acidulated) and non-conventional sources are discussed in terms of (1) contamination of soils and plants with toxic heavy metals, such as cadmium (Cd), and (2) the contribution of P runoff to eutrophication. Best practices of integrated nutrient management should be implemented when applying P fertilizers to different cropping systems. The ideal management system will use appropriate sources, application rates, timing, and placement in consideration of soil properties. The goal of P fertilizer use should be to optimize crop production without causing environmental problems. [ABSTRACT FROM AUTHOR]

This study aims to apply the virtual reality–geography information system (VR-GIS) to the construction of the stratigraphic structure model in the mining area, so as to provide important reference value for the mining and exploration of coal resources, and information management of the geological data. The processing and reconstruction of geological data, the analysis and comparison of geological data interpolation method, and the 3D stratigraphic model method based on digital elevation model (DEM) are analyzed and explored. The results show that stratification and numbering of borehole data histogram can improve the efficiency of database establishment and stratum information extraction; the data of drilling point are encrypted by different spatial interpolation methods, and the analysis and comparison of the four spatial interpolation methods using sample test error method shows that the relative error value and absolute error value of Kriging spatial interpolation algorithm are smaller than those of the other three methods, among which the relative error is controlled within 2%. The irregular triangle network (TIN) algorithm is used to transform raster data into curved 3D layer when establishing 3D stratigraphic model based on DEM. Finally, the 3D stratigraphic space model is obtained by VC++ and DirectX. In conclusion, the borehole histogram is used as the geological data source, the data of borehole points are interpolated and encrypted to obtain raster data by kriging spatial interpolation algorithm, the high-precision 3D stratigraphic model is obtained by TIN algorithm based on DEM, and the 3D stratigraphic spatial model of mining area is visualized by VC ++ and DirectX. [ABSTRACT FROM AUTHOR]

Atmospheric mercury sink in Amazonian rainforest was tested in this work. Forest soil was analyzed for 11 soil profiles at depths of 0-40 cm in the northern portion of the Tapajos National Forest, Brazilian Amazon. Major oxides and Hg contents in soil and rock were determined by XRF and by Zeeman AAS, respectively. A mercury content of 146 μg kg−1 was found in the bedrock, whereas the mercury content in soil averaged 240 μg kg−1. The soil pH varied from 4.4 to 5.2 and the organic matter contents varied from 1.4 to 7.5%. Enrichment factors of Hg for soil were calculated in relation to the parental bedrock assuming aluminum as immobile element. The lower soil layers presented mercury enrichment of 29-98% in comparison to the bedrock. The upper soil layers showed mercury enrichment of 4-24% in comparison to lower soil layers. Mercury in soil was highly correlated with Al, Fe, and Ti; however, no significant correlation was observed between Hg and organic matter contents. All results pointed to mercury retention in forest soils as a result of the combined action of rock weathering processes and continuous input of metal from the atmosphere, estimated to be between 31 and 46% of the total Hg in the upper soil layers. These results are consistent with the hypothesis that the Amazon rainforest is a sink for atmospheric Hg and they also highlight the role of rainforest as a barrier for a number of substances associated with suspended atmospheric particulate. [ABSTRACT FROM AUTHOR]