Iron Oxide Content Research Articles

Class classification of glass products based on K-means clustering

The main raw material of glass is quartz sand, due to the high melting point of pure quartz sand, to reduce the melting temperature, it is necessary to add fluxes during refining. Different fluxes are added, and their main chemical composition is also different. To accurately classify high potassium glass and lead-barium glass, this paper establishes a K-means clustering model to classify glass types. High potassium glasses were classified into three subclasses by the content of iron oxide and barium oxide and lead barium glasses were classified into three subclasses by the content of magnesium oxide and barium oxide. Sensitivity analysis was performed on the model and the results remained significantly correlated.

Process Improvement of Biogas Production from Sewage Sludge Applying Iron Oxides-Based Additives

Iron additives are effective in the anaerobic sewage sludge digestion process, but the composition and dosage of these additives are not precisely defined. This research investigates the effects of three iron oxides-based additives on the destruction of volatile solids, the production and quality of biogas, as well as the quality of the supernatant. Additive No 1 contained >41.5% of FeO and >41.5% of Fe2O3, additive No 2 contained ≥86% of Fe3O4, and additive No 3 contained ≥98% of Fe3O4. The best results were obtained by applying an iron oxides-based additive with a higher content of divalent iron oxide. The increase in efficiency of the VSs destruction was not significant and on average 2.2%. The increase in biogas production was on average 20% while the average increase in the content of methane in the biogas was 6.3%. Applying the additive, the reduction in the concentration of ammonium nitrogen in the supernatant was up to 28%, as well as a reduction in the concentration of phosphate phosphorus in the supernatant by up to 3.1 times could be expected compared to the case when the additive was not applied. The dose of additive No 1 was between 7.5 g/kg of dry solids and 15 g/kg of dry solids in the lab-scale test. The dose was specified in the full-scale test, and the recommended dose of the additive was 10 g/kg of dry solids to improve biogas production.

A Study on the History of Advances in Ancient Iron Making Based on Correlation of Oxides in Slag

A lot of slag was produced by ancient production processes such as smelting, melting, and refining. Iron slag has information that can be used to determine the characteristics of the site, the iron-making process and manufacturing date, but there is a limit to reading information through visual observation and nondestructive analysis. Various slag terms have been used depending on the location and characteristics, but it is necessary to use terms that have exact meaning and unity. Although many scientific analyses have been supplemented by archaeological theses, the iron-making trends of each period have not yet been systematically proven. This study reviewed the type of iron-making process used for 100 ancient slags. The slags were analyzed by XRF, revealing when it was formed and some of the detailed processes. XRD analysis was used to define and classify Tap slag, Bloom slag, and Ceramic-rich slag as relative concepts. From the Three Kingdoms Period to the Joseon Dynasty, the amount of temperature variation in the iron-making furnace decreased and the GAS reaction became uniform. It was observed that the amount of iron oxide remaining decreased and the proportion of ceramic-rich slag increased. The change in iron oxide content kept decreasing while the levels of refining, smelting, and melting were maintained, in that order. The results confirmed that advances in ancient iron-making technology can be interpreted based on a comparative review of the relative changes in iron oxide and silicon oxide content in slag.

Goethite affects phytolith dissolution through clay particle aggregation and pH regulation

Formed in plant tissues as fine silica particles, phytoliths are deposited within plant debris in soils where they can dissolve and feed silicon (Si) fluxes to the biosphere and hydrosphere. Yet, soil phytoliths can be protected from dissolution by entrapment in aggregates, and thus be withdrawn from the global silica cycle. Among clay-sized minerals interacting in stable aggregates, goethite and kaolinite are ubiquitous in soils. We analyzed the impact of goethite-mediated aggregation on the release of aqueous Si from phytoliths entrapped in microaggregates containing organic matter and kaolinite, with quartz and goethite at variable concentrations, simulating a soil sequence with increasing contents of clay and iron oxide, as it can commonly occur in terrestrial ecosystems. The microaggregates stored sizable amount of organic carbon, the release of which decreased with increasing goethite concentration. Aqueous Si was assessed through a kinetic extraction with dilute CaCl2, while pH, aluminum (Al) and germanium (Ge) concentrations were measured in the CaCl2 extracts. Our experimental data showed that phytoliths were the source of aqueous Si. They also showed that the process of phytolith dissolution prevailed over Si adsorption on goethite. As mediated by goethite, aggregation protected phytoliths from dissolution at goethite concentrations above 20 g kg−1. Increasing goethite concentration enhanced aggregation on the one hand, but increased pH from 5.5 to 7.5 on the other. Thus, while aggregation significantly reduced the release of aqueous Si by 1.7- to 3-fold at a given pH, the increase in pH enhanced it. Overall, at common soil solution pH (5–6), aggregation reduced Si release by 2–3 times. Thus, preservation of phytoliths in aggregates can be widespread in well-aerated soils and more effective than Si adsorption on secondary oxides in retaining Si.

Erosion mode and history of Eastern Adamaoua landscapes (Cameroon): Superimposed lateritic weathering of granites and basalts

Landscapes of eastern Adamaoua highlands have been shaped by successive weathering and erosion processes of Pan-African crystalline rocks and Neogene volcanics cover. Basalts have outpoured through major inherited structural discontinuities mostly in shallow incisions of lateritic pediplains previously shaped on the granitic basement. That has resulted in formation of a singular composite lateritic weathering profile on basalt superimposed to a truncated profile composed of mottled clays and saprolite on granite. The composite profile studied here is little evolved, mostly kaolinised on granite while basalt is weakly to moderately lateritised owing to differences in silica and iron oxide contents of the two contrasted parent rocks. During lateritic weathering, Cu, Ni, and Co are enriched in profile on granite but depleted on basalt, while Zr/Ti is relatively constant. Behavior and fractionation of REE are comparable except higher Eu* and Ce* anomaly on granite profile than on weathered basalt, owing to parent minerals differences, mostly feldspars in granite versus plagioclase and Fe-Mg minerals in basalt. The contrast in Eu* is also linked to differences in the Index Of Laterization (IOL) in weathered horizons of the two parent rocks. Beyond quite classical litho-dependent geochemical differences in the composite profile, persistence of per-humid climate and good drainage over Neogene have sustained rock-weathering and local surface erosion processes upon volcanic outpours and their contact surface with pediplains formed on Pan-African granitoids of Adamaoua highland.

Advanced high-iron coal fly ash zeolites for low-carbon emission catalytic combustion of VOCs

Coal fly ash zeolites (CFAZs) with increased iron oxide content were prepared by double-stage alkaline conversion of high-iron lignite coal ash. Catalysts were modified by applying radiofrequency plasma treatment with trifluoromethane (RF CHF3) to increase their surface activity. Textural, compositional, and structural characterization of the parent and plasma-modified zeolites were performed by N2-physisorption, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FT-IR) spectroscopy. Oxidation state and coordination of iron species were studied by Mössbauer spectroscopy, UV-Vis spectroscopy and temperature-programmed reduction method (TPR). Acidic properties were investigated by FT-IR spectroscopy of adsorbed pyridine. The initial and plasma-modified samples were studied under toluene oxidation, where toluene was used as a model VOC. The plasma-modified iron-enriched zeolite was found to exhibit high catalytic activity for VOC oxidation, reaching a 98% toluene conversion rate at 500 °C. Despite some structural degradation effects, the plasma-treated catalysts outperformed the untreated ones in catalytic activity. Furthermore, CO2 adsorption capacity of the plasma-modified zeolite was investigated under dynamic conditions. Although plasma-treated iron-enriched zeolite showed relatively low specific surface area (194 m2/g), high dynamic carbon capture capacity of 3.8 mmol/g was measured. It significantly exceeded the capacity of CFAZs with higher specific surface area, not to mention the pure zeolite phase.

Magnetically-actuated hydrogel-based achiral planar microswimmers for SERS detection: In situ coprecipitation for continuous loading of iron oxide nanoparticles.

Ultraviolet lithography is a very promising technology used for the batch fabrication of biomedical microswimmers. However, creating microswimmers that can swim at low Reynolds number using biocompatible materials while retaining strong magnetic properties and excellent biomedical functionality is a great challenge. Most of the previously reported biomedical microswimmers possess either strong magnetic properties by using non-biocompatible nickel coating or good biocompatibility by using iron oxide particle-embedded hydrogel with weak magnetism, but not both. Alternatively, iron oxide nanoparticles can be coated on the surface of microswimmers to improve magnetic properties; however, this method limited the usability of the microswimmers' surfaces. To address these shortcomings, this work utilized an in situ synthesis technique to generate high magnetic content inside hydrogel-based achiral planar microswimmers while leaving their surfaces free to be functionalized for SERS detection. The hydrogel matrices of the magnetically actuated hydrogel-based microswimmers were first prepared by ultraviolet lithography. Then, the high concentration of iron oxide was achieved through multiple continuous in situ coprecipitation cycles. Finally, the SERS detection capability of magnetically actuated hydrogel-based microswimmers was enabled by uniformly growing silver nanoparticles on the surface of the microswimmers. In the motion control tests, the microswimmers showed a high swimming efficiency, high step-out frequency, and consistent synchronized motion. Furthermore, the magnetically actuated hydrogel-based microswimmers were able to improve the detection efficiency of analytes under magnetic guidance.

A semi-analytical radiative transfer model for explaining soil spectral features

Spectral techniques play a key role in the estimation of large-scale soil parameters, but most of the current estimation models are data-driven models lacking a physical basis. Therefore, in this study, we developed a novel radiative transfer model named the soil multifactor radiative transfer (SMRT) model that predicts the soil spectra as a function of the soil organic matter (SOM), particle size distribution (PSD), and iron oxide content. The SMRT model explains the soil spectral features commonly used in the data-driven estimation models and can be used to explore the mechanisms by which soil-related parameters affect soil spectra according to the model parameters. A total of 79 soil profile datasets were used in the experiments conducted in this study. The reflectance of the soil after air-drying can ignore the effect of moisture, thereby ensuring that the main influences on the soil spectra are the SOM, iron oxide content, and PSD. The SMRT model performed very well in the spectral simulation (R2 = 0.9681, RMSE = 0.0266, MAE = 0.0160). The absorption and scattering coefficients of the SMRT model explain the radiative transfer mechanism for the color representation of black soil and laterite soil. The spectral features around 1910 nm and 2210 nm are caused by not only the soil moisture (SM) and clay mineral content, but several other factors, including the SOM, iron oxide content, and PSD. Overall, these findings show that the SMRT model has a superior ability to describe the soil radiative transfer processes. However, as the coefficients in the SMRT model are dependent on the soil properties, the coefficients should be calibrated by an optimization algorithm and cannot be constants, which leads to the requirement for soil samples to calibrate the coefficients in practical applications.

Synergistic effects and mechanism of the ternary flux system Fe2O3-CaO-MgO on the coal ash slag fluidity

Basic oxides are usually widespread in low-rank coals and cause many ash-related problems in gasification applications. In this paper, the synergistic effects of the ternary flux system of Fe2O3-CaO-MgO in lowering the ash fusion temperature and improving the viscosity-temperature characteristics were verified by testing the properties of samples with different Fe2O3/(CaO + MgO) ratios. The flow temperatures and temperatures of the critical viscosity decreased and then increased with the decrease of Fe2O3/(CaO + MgO) ratio and reached the lowest point when the iron oxide and alkaline earth metal oxide (CaO, MgO) contents were close to each other. From the perspective of mineral transformation, the formation of low melting point ferroan spinel and the eutectic between anorthite and ferroan spinel are the main mechanisms of synergism. No severe crystallization was observed in the iron-rich slags because Fe2+ could reduce the crystallization tendency. As CaO and MgO dominated the basic oxides, a CaO/MgO ratio of 4:6 effectively limited the crystallization and lower the temperature of critical viscosity (TCV). Thus, when regulating the coal ash fluidity, the content of iron oxide and the ratio between CaO and MgO should be consciously balanced to meet the requirements of the gasifier for slag removal.

Response of soil iron oxides in freshwater marsh to different tidal hydrology in the Yellow River Estuary wetland, China

Iron cycles is essential for the transition of matter and energy in wetland ecosystems. The tidal hydrology is a critical factor controlling soil iron biogeochemistry in estuarine wetland, but it remains unclear how iron oxides response to tidal hydrologic regime. A field experiment was manipulated in the Yellow River Estuary wetland for 23 months to differentiate change in iron oxides of freshwater marsh soil under different tidal hydrologic regimes. In June 2019, soil cores were collected in the freshwater marsh on the supratidal zone (FPA), and translocated to be cultured in the tidal salt marshes on the intertidal zone (SPA, TC and SS). Over 23 months, tidal hydrologic regime had obviously affected soil properties and iron oxides. Under the tidal regime, there was an increase in soil pH and electric conductivity (EC), and a decrease in soil water content (SWC), total nitrogen (TN), total phosphorus (TP) and total organic carbon (TOC). A total decrease was found in the contents of soil iron (FeT), iron oxides (Fep, complexed iron; Feo, amorphous iron; Fed, free iron) and their ratios (Fep/Fed, Feo/Fed and Fed/FeT). The duration of tidal hydrology affected the contents of iron oxides and their ratios, i.e., FeT and Fed decreased with culture time in all sites while Fep, Feo and the ratios increased in the supratidal site. Iron oxides and their ratios were positively correlated to redox potential, organic carbon and nutrients, and negatively correlated to soil pH and salinity. The results indicate that tidal hydrologic regime could decrease the contents of soil iron oxides and their activation when freshwater marsh exposed to tide events.

Analysis and Prediction of Chemical Composition of Ancient Glass Relics

Glass was introduced into China long ago via the Silk Road. After the ancient glass was buried, its internal elements would change under the influence of the environment. It is of great significance for archaeological work to study the changes of these chemical components. In this paper, the chemical composition of ancient glass products is analyzed and predicted by using R-type clustering, BP neural network, multiple linear regression and other models.First, after using SPSS statistical data, Pearson chi square test was conducted to draw a conclusion that the category, decoration and color were not related to whether the surface of the cultural relics was weathered. Then, descriptive statistics are made on the data. Finally, the multiple linear regression model is used to predict the unknown type of cultural relics. The results show that after the weathering of cultural relics, the content of potassium oxide, calcium oxide, aluminum oxide and magnesium oxide decreases compared with that before weathering, while the content of iron oxide increases.The main chemical components of high potassium glass relics and lead barium glass relics are calculated by entropy method. Compared with silicon dioxide and aluminum oxide, they have less influence on other chemical components. Therefore, these two chemical components are eliminated to classify cultural relics. Then, the R-type clustering model is established to classify the cultural relics, and the high potassium weathering type is obtained: 22 cultural relics sampling points form a category, and the other cultural relics form a category.

The Correlation of Colour and Iron Oxides in Yellow Seal Stones from Northern Laos

The yellow seal stone from northern Laos is one possible substitute for the Tianhuang Stone, the most famous Chinese seal stone, because of its similar yellow to orange-yellow appearance and the same main mineral composition. The colour causation of the yellow seal stone from northern Laos was studied. The samples’ phase, micro-morphology and chemical components were studied by Raman spectroscopy, and scanning electron microscopy (SEM) with energy disperse spectroscopy (EDS), respectively. The yellow seal stone from northern Laos is mainly composed of dickite, occasionally with minor impurity minerals, such as hematite, anatase, barite, diaspore and pyrite. Micro- to nano-sized iron oxides/hydroxides were observed and detected by SEM and EDS in the yellow to orange-yellow part of the samples. Moreover, these iron oxides/hydroxides were suggested to cause the yellow to orange-yellow in the seal stone from northern Laos. The UV-Vis spectrum and its second derivative, the Kubelka-Munk spectra, were used to identify and quantify hematite and goethite. The samples’ colour parameters were obtained with the Commission Internationale de l’Eclairage (CIE) 1931 standard space. According to the observation of the samples and the results obtained from experiments and calculations, the colour of the yellow parts (L* = 33.56~47.99, a* = 0.35~3.65, b* = 4.55~9.89) correlated with goethite (goethite is about 0.175~0.671 g/kg, the content of hematite was too low to be figured out in the yellow parts). In contrast, the colour of the orange-yellow parts (L* = 33.99~46.27, a* = 3.98~12.39, b* = 8.04~22.14) was more closely related with the content of hematite (goethite is about 0.096~0.691 g/kg, hematite is about 0.258~2.383 g/kg). The results of correlation analysis also support that the contents of iron oxides or hydroxides influence the samples’ colour. Therefore, it is suggested that micro- to nano-scaled hematite and goethite caused the colour of yellow and orange-yellow in the studied seal stone. Hematite can strengthen the red hue and change the colour from yellow to orange-yellow.

PM10 Resuspension of Road Dust in Different Types of Parking Lots: Emissions, Chemical Characterisation and Ecotoxicity

The thoracic fraction of road dust (PM10) was measured for the first time in Portugal in parking areas, both outdoors and indoors, with the aim of completing existing studies carried out in active lanes of various roads. An in situ resuspension chamber was used to collect a total of 23 samples in three parking areas of Aveiro, whilst the laboratory procedures included determination of carbonaceous content (OC and EC) by a thermo-optical technique, elemental composition by ICP-MS and ICP-OES after acid digestion, and the Aliivribrio fisherii bioluminescent bacteria ecotoxicity bioassay. Dust loadings (DL10) obtained were 18.5 ± 9.8 mg PM10 m−2, in outdoor parking, and 1.8–23.7 mg PM10 m−2 for indoor parking, corresponding to emission factors of 476 and 75–589 mg veh−1 km−1, respectively. OC represented 9–30 % of PM10 for the indoor parking areas. However, for the outdoor samples, the high iron oxide content jeopardised the OC-EC separation. In those samples, carbonates accounted for 10.0 ± 3.3% of the PM10 mass. The analysis of elemental components focused on major elements (Al, Ca, Fe, K, and Mg) as well as minor elements. The total mass fraction of element oxides accounted for 27.1% (outdoor) and 23.6–34.3% (indoor). ΣPAH calculated for all parking areas accounted for 8.38–36.9 μg g−1 PM10. The ecotoxicological bioassay showed that all aqueous solutions were toxic to bioluminescent bacteria, whereas no clear correlations could be made with specific component groups, with the exception of ΣPAH and EC50.

Study of the Effects of Solution Types on Concentration of Iron Oxide by Pulsed Laser Ablation in Liquid

In this work, the development of nanosystems by Pulsed Laser Ablation in Liquid (PLAIL) is of considerable importance to expand their biomedical applications, such as drug delivery. In the present study, we focus on the conditions of the preparation Nd: YAG laser wavelength 266 nm and two different laser fluency (10,28) J/cm2 to control the concentration and size stability of superparamagnetic iron oxide nanoparticles (SPION) prepared by PLAIL. The characteristics of SPION are investigated by energy-dispersive X-ray spectroscopy (EDX) spectra which showed strong peaks of Fe and O. Magnetic characteristics of iron oxide nanoparticles indicated superparamagnetic properties of SPION and suitable physical stability. Optical and chemical properties of SPION were investigated using UV-visible spectra (UV) and infrared Fourier transformed spectroscopy (FTIR). . Scanning electron microscopy (SEM) was used to obtain surface morphological studies of SPION.. Results showed that SPION is the only cubic shape, the peak absorption shifted toward short wavelengths with optimum concentration to the SPION in double deionized water (DDW) and in Acetone (0.75,0.33) mg/ml respectively, at high laser fluence 28 J/cm2, and this enhancement of value is due to particle size and color resultant in a solution. Eventually,, this product has the optimal SPION specialty ratio of SPION in the DDW solution at 53.89%, and the size is very suitable for drug delivery applications.

An experimental investigation of factors controlling the oxygen content of sulphide melts in the Earth’s upper mantle

To determine the factors that control the oxygen content of sulphide melts in the upper mantle, mono-sulphides were equilibrated with mantle peridotite assemblages, with varying FeO and NiO contents, between 3 and 13 GPa and 1300 to 1819 °C. Carbonates were added as a flux and the use of graphite capsules allowed oxygen fugacities (fo2) to be estimated for most of the experiments. Sulphide melt O concentrations were in the range 0.2–3.7 wt. %, coexisting with silicate assemblages with olivine Fe/(Fe + Mg) ratios between 0.04 and 0.25. Except in Ni-bearing experiments, variations in the sulphur/metal cation ratio did not affect the sulphide melt O contents, which also appeared to be independent of fo2. The silicate FeO contents, temperature and pressure were found to be the main controls on O contents. Nickel lowers the O content, although all Ni-bearing experiments produced sulphides with lower sulphur/metal ratios, making it difficult to categorically separate the effect of Ni alone. A preliminary geothermometer expression was developed based on the O content of the sulphide melts and the iron oxide concentrations of coexisting olivine and orthopyroxene. With this expression, the experimental temperatures are reproduced to within 74 K for Ni-free experiments and within 135 K for Ni-bearing samples. Using measurements of the O contents of sulphide inclusions of peridotite affinity in diamonds from the Lac de Gras kimberlite field, a plausible average entrapment temperature of 1318 ± 48 °C is calculated. Mantle peridotite assemblages would be expected to contain sulphide melts with approximately 0.4–0.6 wt. % O along a typical mantle adiabat down to 200 km depth.

Characterization of Serpentine Soils from Eastern and Southern Rhodope Mountains (Bulgaria)

This work aims to characterize serpentine soils in Bulgaria and examine the biogeochemistry of pedogenic Ni and its relation to Ni available forms. Soils were collected from serpentine soils of the Eastern and Southern Rhodopes (Bulgaria). The chemical composition of serpentine soils is similar to serpentine soils from the Balkan Peninsula and is characterized by high contents of Ni (919.9–2397.2 mg.kg–1). The soils had a neutral to slightly alkaline reaction (pH 6.4 to 7.6) and a medium to high organic matter content. Of the primary minerals, those of the serpentine group (antigorite and lizardite), the talc group (willemseite), the amphibole group (riebeckite), the feldspar group (albite) and quartz are mainly present in the soil samples. The secondary minerals present in the samples include calcite and dolomite, and also representatives of the clay minerals, clinochlore and montmorillonite. The contents of free iron oxides (Fed), amorphous iron oxides (Feo), well-crystallized iron oxides (Fecr) (Fed-Feo) and activity index (Feo/Fed) showed significant differences (p<0.05) among soils from different locations. In the soils from Dobromirtsi, Parvenets, and Golyamo Kamenyane Ni bound to Fe oxides were evenly distributed between the well-crystallized and amorphous phases. In the soils from Kardzhali, Chernichevo and Dyulitsa more than half of the Ni bound to Fe oxides were bound to or occluded in amorphous Fe oxides, while in the soils from Kazak were bound to well-crystallized Fe oxides. Pedogenesis, weathering intensity, and Fe geochemistry influence Ni availability in serpentine soils.

Structure and redox ratio of soda‐lime‐silica glasses with high iron oxide concentrations

AbstractThe high temperature synthesis of glasses in the system (100‐x)(0.16Na2O/0.10CaO/0.74SiO2)/xFe2O3, x = 5 ÷ 20 mol% is reported. For Fe2O3 concentrations ≤15 mol%, glasses are formed while the sample with 20 mol% crystallizes during cooling the melt. X‐ray diffraction shows the crystallization of magnetite. The microstructure of the glass‐crystalline sample is investigated by optical microscopy and scanning electron microscopy and two types of iron‐rich crystals corresponding to magnetite and hematite are detected. The refractive indices as determined by the Becke line method are in the 1.567 ‐ 1.639 range and. increase with increasing Fe2O3 concentration. The structure is characterized using Infra‐red spectroscopy. The presence of symmetric stretching, asymmetric stretching and bending vibrations of Si‐O‐Si is detected and attributed to the occurrence of SiO4 tetrahedral units with varying numbers of nonbridging oxygens. Also, the increasing Fe2O3 concentration results in occurrence of Fe‐O‐Si bonds indicating the glass network depolymerization due to Fe2O3 addition. In all samples, the presence of Fe3+ and Fe2+ and the existence of iron ions in tetrahedral and octahedral coordination, as well as a very small amount of Fe0 and the precipitation of hematite and magnetite in the glass‐crystalline sample is revealed by Mössbauer spectroscopy.

Color changes in yardang strata sediment in the Dunhuang Yardang National Geopark, Northwest China: Controlling factors and significance for sedimentary environments

Introduction: Yardang stratum is the basic material unit of yardang landforms. Due to their protracted age and complex sedimentary structure, formative yardang stratum mechanisms remain poorly understood. Color, being one of the most intuitive, easily accessible, and important lithological indicators, can be used to identify yardang strata sedimentary environments. However, the lack of quantitative analysis and systematic research have limited how chromatic environmental proxies can be extracted and interpreted.Materials and methods: The Dunhuang Yardang National Geopark was selected for this experiment. Based on chromaticity, grain-size, chemical element, organic matter, and carbonate content measurements of yardang strata sediment samples, this study used correlation analysis and chromaticity proxy extraction to quantitatively characterize associated color changes, controlling factors, and sedimentary environments.Results and discussion: Results found significant cyclic changes in chromaticity parameter curves were observed in the profiles, which is likely indicative of a dry/wet evolutionary process that occurred during different stages of the yardang sedimentary environment. Organic matter content was the main factor affecting changes in brightness, while iron oxide content directly affected yardang sediment redness and yellowness values. Due to its low value, effects of carbonate content on brightness were obscured. The grain-size characteristics indirectly affect the brightness value through the content of quartz, feldspar and organic matter. Moreover, based on modern analogy method, the brightness and redness values are proved to be effective proxies for distinguishing the yardang sedimentary environment. Accordingly, it is concluded that the sedimentary environment of Dunhuang yardang landforms is composed of sedimentation that derived from lacustrine, aeolian, and alluvial environments, and that the chromaticity parameter range and characteristic color for sedimentary environments are extracted and quantified. Findings from this study not only rectify the lack of quantitative research on yardang sediment color theory but also provide an important theoretical basis for identifying sedimentary environments in the field.

Prediction of Phosphorus Sorption Index and Availability by NIR and MIR in Soils in Madagascar

The development of techniques for the rapid, inexpensive, and accurate determination of the phosphorus (P) availability and sorption index (PSI) in soils is important for P management in highly weathered tropical soils. The applicability of near- and mid-infrared reflectance spectroscopy (NIR and MIR) as tools for estimating P availability and PSI was assessed over a wide range of highly weathered soils in Madagascar. The predictions were based on chemometric methods using multivariate calibration models with partial least squares (PLS) regressions, and pedotransfer functions (PTFs). Chemometric methods failed to predict available P (Presin). However, a P sorption index, determined as the P remaining in solution (Prem), was estimated with acceptable accuracy with both NIR and MIR (R2cv = 0.70 − 0.73; R2v = 0.65 − 0.77; SEP(c) = 5.5 − 4.6 mg kg−1). The PTFs showed that the PSI was well explained by iron oxide, gibbsite, and sand contents, all of these compounds being well predicted by NIR or MIR (R2v > 0.70). These results indicate that NIR and MIR can be helpful for a rapid estimate of PSI of highly weathered ferralitic soils.

Assessment of sol-gel derived iron oxide substituted 45S5 bioglass-ceramics for biomedical applications.

Magnetic bioactive glass-ceramic (MGC) powders with nominal compositions of (45 - x)SiO224.5CaO24.5Na2O6P2O5xFe2O3 (x = 2, 4, 6, 8, 10, and 15 wt%) have been synthesized by a sol-gel route by systematically substituting silicon dioxide with iron oxide in Hench's 45S5 glass composition. Powder X-ray diffraction studies revealed a variation in the percentage of combeite (Ca2Na2Si3O9), magnetite (Fe3O4), and hematite (Fe2O3) nanocrystalline phases in MGC powders as a function of composition. Zeta potential measurements showed that MGC containing up to 10 wt% iron oxide formed stable suspensions. The saturation magnetization and heat generation capacity of MGC fluids increased with an increase in iron oxide content. Degradation of MGC powders was investigated in phosphate buffered saline (PBS). The in vitro bioactivity of the MGC powders taken in pellet form was confirmed by observing the pH variation as well as hydroxyapatite layer (HAp) formation upon soaking in modified simulated body fluid. These studies showed a decrement in the overall bioactivity in samples with high iron oxide content due to the proportional decrease in the silanol group. Monitoring the proliferation of MG-63 osteoblast cells in Dulbecco's Modified Eagle Medium (DMEM) revealed that MGC with up to 10 wt% iron oxide exhibited acceptable viability. The systematic study revealed that the MGC with 10 wt% iron oxide exhibited optimal cell viability, magnetic properties and induction heating capacity, which were better than those of FluidMag-CT, which is used for hyperthermia treatment.