Ca Ratios Research Articles

Diversity of life history and population connectivity of threadfin fish Eleutheronema tetradactylum along the coastal waters of Southern China

Understanding the diversity of life history, life stage connectivity and population is essential to determine the spatial scale over which fish populations operate. Otolith microchemistry analysis is a powerful tool to elucidate the life history and population connectivity of fish, providing important insights to the natal origin and population structure. In this study, we used laser ablation inductively coupled plasma mass spectrometry to analyze the chemical composition of otoliths throughout the entire lifetime of endangered fourfinger threadfin species, Eleutheronema tetradactylum. We reconstructed the life history of E. tetradactylum from Southern China collected from different locations over a spatial scale of 1200 km. Sr:Ca and Ba:Ca ratios profiles from otolith core-to-edge analysis suggested two contrasting life history patterns. Based on the differences in early life stages, we identified some fish spending their first year in an estuarine environment with subsequent movement to marine coastal systems, while some fish remaining in the coastal systems throughout their entire early life history stages. The non-metric multi-dimensional scaling showed a strong overlap in otolith core elemental composition, indicating a large-scale connectivity in the life history of E. tetradactylum. The immature fish from different natal origins mixed to a large extent when they fed and overwintered in the extensive offshore waters. Clustering of near core chemistry pointed to three possible sources of nursery for the threadfin fish. This study demonstrated the diversity of life history patterns of E. tetradactylum in Southern Chinese waters. Restoration in egg and larvae densities in coastal waters and estuaries may enhance their population abundances.

Bioactive Carbonate Apatite Cement with Enhanced Compressive Strength via Incorporation of Silica Calcium Phosphate Composites and Calcium Hydroxide.

Carbonate apatite (CO3Ap) is a bioceramic material with excellent properties for bone and dentin regeneration. To enhance its mechanical strength and bioactivity, silica calcium phosphate composites (Si-CaP) and calcium hydroxide (Ca(OH)2) were added to CO3Ap cement. The aim of this study was to investigate the effect of Si-CaP and Ca(OH)2 on the mechanical properties in terms of the compressive strength and biological characteristics of CO3Ap cement, specifically the formation of an apatite layer and the exchange of Ca, P, and Si elements. Five groups were prepared by mixing CO3Ap powder consisting of dicalcium phosphate anhydrous and vaterite powder added by varying ratios of Si-CaP and Ca(OH)2 and 0.2 mol/L Na2HPO4 as a liquid. All groups underwent compressive strength testing, and the group with the highest strength was evaluated for bioactivity by soaking it in simulated body fluid (SBF) for one, seven, 14, and 21 days. The group that added 3% Si-CaP and 7% Ca(OH)2 had the highest compressive strength among the groups. SEM analysis revealed the formation of needle-like apatite crystals from the first day of SBF soaking, and EDS analysis indicated an increase in Ca, P, and Si elements. XRD and FTIR analyses confirmed the presence of apatite. This combination of additives improved the compressive strength and showed the good bioactivity performance of CO3Ap cement, making it a potential biomaterial for bone and dental engineering applications.

Geochemical proxies of sea surface temperature from MIS 5e marine fossils in the Taranto Gulf (Ionian Sea, Southern Italy)

Well preserved fossil specimens of Thetystrombus latus, Spondylus gaederopus, Venus verrucosa, Pinna nobilis and Cladocora caespitosa, all coming from a MIS 5e fossiliferous calcarenite outcropping along the Mar Piccolo of Taranto coastline, were analyzed for trace elements and ∂18O and ∂13C isotopic composition in the carbonates of skeletons; with the aim to estimate the Sea Surface Temperature (SST) using different published equations. The adopted methods gave close values of the mean SST, even if with wide standard deviation values: 21.6 °C and of 21.1 °C, derived respectively from the Mg/Ca ratio of P. nobilis and from the Sr/ Ca ratio of C. caespitosa; 19.6 °C derived from the of C. caespitosa growth rate; 21.0 °C derived from the ∂18O. The similarity of these mean results could indicate that a moderate warming with an average of 2.8 °C, in respect to today, is the most likely climatic scenario of the Mar Piccolo of Taranto during the MIS 5e.

Utilising Thermodynamic Equilibrium Calculations to Model Potassium Capture by Aluminosilicate Additives in Biomass Combustion Plants

When it comes to the modelling of solid aluminosilicate additive particles, many current attempts are still using a high-level approach, leaving out the mechanistic detail on a particle level to reduce model complexity. This paper shows different ways in which thermodynamic equilibrium calculations can help to understand the processes inside additive particles and to generate sub-models for detailed CFD-calculations. First, the influence of the additive's chemical composition (Al/Si ratio and traces of Ca, Mg, Fe, Ti) on its maximum capture value is investigated. Afterwards, two sub-models for the behaviour of additives in combustion chambers are presented: one model for the calculation of the loss in surface area inside a particle, as well as a model for the in-situ determination of an additive particle's capture ceiling function. The results show that the chemical composition of the additive plays an important role in determining the capture of potassium from flue gases. High Al/Si ratios lead to higher thermal stability of the particles, while simultaneously reducing the amount of potassium that is captured in equilibrium. This knowledge can help improve models of solid additive particles and help optimise their use in thermal power plants.

Sr2+-dependent microstructure regulation of biodegradable Sr-doped hydroxyapatite microspheres with interconnected porosity for sustained drug delivery

The microstructure and compositional tunability of hydroxyapatite (HA) microspheres, as well as their limited biodegradability, have been challenges for their use as carriers in drug delivery systems. In this study, strontium-doped HA (Sr-HA) microspheres with interconnected porosity and pore channels were successfully prepared under the regulation of Sr2+ via a hydrothermal method. The morphologies, scales, constituents, and pore geometries of Sr-HA microspheres were modulated by the concentration of Sr2+. SEM and TEM observations revealed that diverging, dense flower-like, hierarchical porous, and trumpet-shaped macroporous microspheres were obtained as Sr/(Sr + Ca) ratio increased. Correspondingly, the size of the microspheres decreased from approximately 120 μm–15 μm. The introduction of Sr2+ significantly enhanced the biodegradability of the microspheres. Furthermore, the porous Sr-HA microspheres showed superior vancomycin loading capacity (167.5 mg/g) and sustained release properties. This possible microstructure regulation mechanism was discussed based on the experimental results. This study provides a new perspective on material design for various potential applications.

Preparing a Ca-Bi-O System by the Precipitation Method and Studying Its Intermediate Structural Properties for Applications in Water Treatment

This study focuses on the development of a Ca-Bi-O system (CBO) with efficiency in the degradation of Rhodamine B, which is extremely toxic to many organisms and can have long-term negative consequences if not safely removed from the water. The conventional precipitation method was used to create a stable phase of Ca2Bi2O5 with a stoichiometric 1:1 molar ratio of Ca:Bi. Before obtaining the pure phase, the details of the reaction processes were investigated and the various intermediate products were identified using X-ray diffraction followed by Fourier transform infrared, UV-Vis, and Raman spectroscopy. An ab initio calculation evaluated with the HSE06 functional yields a band gap of 3.5 eV, similar to the band gap obtained by diffuse reflectance recorded on Ca2Bi2O5. This newly synthesized compound is addressed to the environmental application by investigating the photocatalytic properties of CBO materials obtained at different calcination temperatures. The investigation of pure Ca2Bi2O5, with characterization techniques and complemented by new first-principles calculations to investigate the photocatalysis provide valuable new insights for this scarcely studied yet potentially interesting compound.

Вплив іонно-сольового складу води на якість пива

Minerals dissolved in water have an important effect on the overall chemistry of the brewing process. Ions from these minerals affect the pH of water, its hardness, alkalinity and mineral composition. These parameters are the most important factors in determining the suitability of water for brewing, in particular for the mashing process. For that reason, it is very important to study the ion-salt composition of mash water and its influence on the quality of beer. The method of regulating the ion-salt composition of water, which is necessary for its use in the mashing process in order to obtain high-quality beer is discussed in the article. Prepared water obtained by reverse osmosis is free from ions as much as possible, which enabled to prepare water with the necessary ion-salt composition for rubbing by adding appropriate salts. Using prepared water in the mashing process, beer samples were obtained, which were evaluated according to sensory and physicochemical indicators. The effect of ion-salt composition of mash water on beer quality indicators was studied. It was found that calcium and sodium cation complexes, as well as a mixture of sulfates and chlorides dissolved in the water used for the mashing process, have the most significant impact on beer quality. Concentrations of individual ions in such water do not show any pronounced dependence on beer quality indicators. It was studied that the increase in the ratio of cations Ca2+/Na+ and sulfates and chlorides SO4 2- /Cl in the mash water has a positive effect on the sensory and quality indicators of beer: the ratio of key ions affects hop bitterness to the greatest extent among the quality indicators of beer. In addition, the ratio of Ca2+/Na+ cations has a positive effect on the foam resistance of beer, and the ratio of sulfates and chlorides SO4 2- /Cl leads to an increase in the share of alcohol in the finished drink. According to the tasting evaluation of beer, samples with a higher ratio of key ions have a brighter taste and aroma.

Features of triamyl citrate synthesis

Objectives. To find an effective way for obtaining triamyl citrate, an environmentally friendly, biodegradable citric acid ester used as a plasticizer for PVC-based polymer compositions.Methods. The possibilities of heterogeneous catalysis were analyzed using the case study of three commercial samples of macroporous sulfocationites (Amberlyst™ 15, Amberlyst™ 70, and TULSION® 66). Homogeneous catalysis was studied using the example of orthophosphoric acid (H3PO4), while self-catalysis was investigated during esterification of citric acid with amyl alcohol (ROH). The syntheses were carried out under identical conditions: T = 110 °C, the ratio of CA:ROH = 1:5 (mol) amount of catalyst 1 wt % on the reaction mass in a thermostatically controlled reactor of ideal mixing with continuous distillation of the resulting water.Results. It was found that in all variants (even under self-catalysis conditions), the conversion of citric acid in 180 min reached 94–99%. Triamyl citrate was formed after 9 h with a yield of 90% only when using a homogeneous catalyst (H3PO4) and in the presence of a heterogeneous catalyst sample (Amberlyst ™ 15).Conclusions. The revealed differences in the reactivity of the studied sulfocationites (Amberlyst™ 15, Amberlyst ™ 70, and TULSION® 66) confirm the well-known theoretical positions, according to which the kinetic pseudo-homogeneous model of the esterification process of hydroxy acids in excess of aliphatic alcohols is based on the law of acting masses and depends on the specific surface area of the catalyst, which for Amberlyst ™ 15 is of the greatest importance as compared to Amberlyst ™ 70 and TULSION® 66 (m2/g): 53:36:35, respectively.

Evaluation of the ratio of different major and trace elements in the lens of dogs with cataract.

Understanding the elements that support cataract development and searching for available therapeutic methods is essential for scientific and social interest. For that purpose, the role of trace elements has been investigated in this study to better understand the development of cataracts in dogs. The aim of this study was to evaluate the ratio of the major and trace elements by X-ray fluorescence spectrometry in dog cataract lenses to contribute to diagnostic, non-surgical, and ophthalmological preventive data. A single lens with a cataract from each of a total of 88 dogs (cataract group) and a healthy lens from each of 6 dogs (control group) were evaluated. The elements calcium (Ca), iron (Fe), copper (Cu), zinc (Zn), magnesium (Mg), manganese (Mn), and potassium (K) were analyzed by energy dispersive X-ray fluorescence and X-ray microfluorescence. The results indicated an increase of Ca, Fe, Cu, and Zn, in association with the reabsorption mechanism of hypermature cataracts. The ratio of elements Ca, Fe, Cu, and Zn was different in cataract lenses than in healthy lenses, and our results may support the development of therapeutic strategies for cataracts in dogs. The Ca concentrations were distinct in the cataract development stages, and the Fe concentration was relatively higher in males when compared to females. Finally, this research stands out with a particular contribution to the understanding of both cataract formation and prevention.

Inferring habitat use of the Pacific White Shark using vertebral chemistry

The conservation and management of highly migratory sharks relies on understanding age-related movements and nursery habitat utilization. We reconstructed the habitat use and migratory history of young White Sharks (Carcharodon carcharias), a highly protected species, by utilizing natural chemical tracers (element:Ca ratios and stable isotope analysis, SIA) in vertebral cartilage growth bands. Two nursery areas in the northeastern Pacific are known, but migration patterns of immature White Sharks within the Gulf of California (GC) and natal philopatry are poorly understood. Vertebrae from coastal Mexican artisanal fisheries off central Baja California in the Pacific (12 neonates and juveniles; 139-280 cm total length) and the GC (3 subadults; 289-355 cm TL) were analyzed to characterize (1) trophic histories from collagen δ13C and δ15N values, and (2) in utero patterns and post-birth environmental histories from element:Ca time-series. Mean δ15N values from vertebral edges of GC sharks, representing the most recent feeding, was +5‰ higher than in the Pacific, reflecting the intense denitrification that permeates the regional food web and supporting SIA as tracers of migration between regions. A subadult from the GC likely resided within the system throughout its life, and two subadults migrated into the GC. Most neonate and juvenile sharks caught in the Pacific had SIA that did not overlap with those of the GC, but a single subadult likely migrated to the GC. Element:Ca ratios displayed ontogenetic trends, with Li:Ca, Zn:Ca, and Ba:Ca significantly higher before the birth mark in sharks captured in the GC. Edge values were significantly higher in Zn:Ca and Ba:Ca in the GC compared to the Pacific, suggesting elemental ratios may serve as tracers of migration between regions. Subadult sharks collected from GC displayed elevated maternal Zn:Ca and Ba:Ca, suggesting mothers may have resided in the GC for an extensive period pre-birth. Some White Sharks may reside within the GC from birth until at least the subadult stage (ca. 3 m TL), and there may be an unidentified nursery. Chemical tracers, coupled with genomic and tagging studies, should improve understanding of the importance of the GC to White Shark populations in the northeast Pacific.

Effect of gamma irradiation on structural, morphological, optical and thermal properties of Ca doped CuO nanostructure thin films

Semiconductor optoelectronic and photonic devices are used in many harsh environment applications such as space and nuclear reactor etc. Gamma radiation in such environments significantly interacts with the semiconductor materials used in these devices, changing their structural, optical, morphological and thermal properties. Therefore, it is vital to investigate the gamma radiation effect of the material to be exposed to radiation in terms of the performance and lifetime of the application. In this study, nanostructured thin films were produced by doping different ratios (0, 0.3, 1.25, 2.5 and 5 mg/mL) of Ca to the copper oxide (CuO) is a semiconductor used in optoelectronic and photonic devices. The thin films produced were deposited on the glass substrate by the spin coating method. The effects of gamma rays on the structural, morphological, optical and thermal properties of the films were investigated by irradiating with different doses (1, 5, 15, 50, 100 and 150 kGy) used a Cobalt-60 gamma radiation source. The structural, morphological, optical and thermal properties of Ca doped CuO nanostructured thin films were investigated by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), atomic force microscope (AFM), mechanical profilometer, UV-Vis spectrophotometry (UV-Vis) and thermogravimetric differential thermal analyzer (TG/DTA). The band gap of thin films were been calculated using Tauc’s plot. The obtained results showed that high-dose gamma radiation caused defects in undoped and Ca doped CuO nanostructured thin films and affected their structural, morphological, thermal and optical properties. Despite the resulting defects, Ca doped CuO nanostructured thin films showed higher absorption intensity and thermal stability against gamma rays. These results showed that Ca doped CuO nanostructured thin films are suitable for many harsh environment applications such as space and nuclear reactors.

Effect of strontium ranelate and cerium oxide addition in the diet on egg production and eggshell quality in laying hen

Minerals are used widely as feed additives in the diets of poultry to enhance bone and egg quality and productivity. Therefore, the current study aimed to evaluate the impact of strontium ranelate and cerium oxide addition in the diet on egg production and eggshell quality in laying hens. In this experiment, a total of 240 laying hens at the age of 44 weeks old, were divided into six treatments, with four replicates per treatment (10 hens per replicate). The hens were fed a standard diet for five weeks as an introductory period of preparation. The design of the dietary treatments was formulated as: control (T1) basal diet, Strontium ranelate (SrR) 400 and 800 mg/kg in basal diet (T2 and T3), Cerium oxide (CeO) 250 and 500 mg/kg in basal diet (T4 and T5) and their combination 400 mg/kg of Strontium ranelate + 250 mg/kg of Cerium oxide (T6) in the basal diet. Laying hen’s performance and, egg quality (eggshell strength, eggshell thickness, eggshell percentage, minerals in eggshell, yolk index and Haugh unit), were analyzed. The results showed that the addition of SrR and CeO did not affect performance, yolk index, Haugh unit, ratio of Ca, P, and Ce in the eggshell. However, supplementing 800 mg/kg SrR significantly increased eggshell strength, thickness, percentage, Sr in the eggshell compared to the control, while supplementing 250 or 500 mg/kg CeO significantly increased eggshell strength and thickness. The combination of SrR and CeO significantly increased eggshell strength compared to the control group. In conclusion, supplementing SrR (800 mg/kg) and CeO significantly improved the quality of the eggshell.

Genesis of the Xianghualing tin-polymetallic deposit in southern Hunan, South China: Constraints from chemical and boron isotopic compositions of tourmaline

The Xianghualing skarn Sn polymetallic deposit (Nanling Range), with ca. 0.25 Mt Sn metal, 0.85 Mt Pb + Zn metal, and 22 Kt (Ta, Nb)2O5, is a Late Jurassic biotite granite-related Sn-Pb-Zn-Nb-Ta deposit. However, our understanding of how magmatic-hydrothermal processes contributed to its mineralization remains poor. Tourmaline has the capacity to retain primary elemental and isotopic information throughout the tin-related ore-formation process, allowing us to use the in-situ major, trace elemental, and boron isotopic compositions of tourmaline to research the origin of tin-bearing fluids and to trace the magmatic-hydrothermal evolution associated with tin mineralization. Five types of tourmaline are recognized based on petrography: i) late-magmatic tourmaline (Tur-I) disseminated in the biotite granites; ii) hydrothermal tourmaline (Tur-II) in massive schorl-fluorite association from the endoskarn zone; iii) hydrothermal tourmaline (Tur-III) with long columnar crystals in massive schorl-epidote association from the exoskarn zone, is related to Sn-Pb-Zn mineralization; iv) hydrothermal tourmaline (Tur-IV) from tourmaline-fluorite veins in exoskarn within the marble; and v) hydrothermal tourmaline (Tur-V) from cassiterite-sulfide-tourmaline-fluorite-topaz veins hosted by quartz sandstone, and is directly related to Sn-Pb-Zn mineralization.Tourmaline from the Xianghualing tin-polymetallic deposit dominates the alkali group and the schorl-dravite solid-solution series. Distinct Fe/(Fe + Mg) and Na/(Na + Ca) ratios of Tur-II to Tur-IV reveal different degrees of B-rich fluid-rock (granite or carbonate) interaction. Trace element variations in tourmaline are principally governed by local fluid-rock interactions and melt/fluid compositions in a low fO2 environment. Late-magmatic tourmaline (Tur-I) and hydrothermal tourmaline (Tur-V) related to vein-type Sn-Pb-Zn mineralization have similar Ca, Na, Al, Mg, Fe, and REE + Y contents, indicating that magmatic-hydrothermal exsolution controls Sn-Pb-Zn enrichment. This process occurs in a reducing environment without significant water–rock reactions, demonstrating that high fO2 or acid-consuming reactions are unnecessary for cassiterite precipitation. Variations in water–rock reactions between magmatic fluids and the carbonates cause differences in tourmaline elemental concentrations (e.g., Ca, Al, and Pb) between the magmatic and skarn phases. There are two main paths of tin mineralization in the Xianghualing deposit: (1) fluorine- and boron-rich fluid exsolution at the magmatic-hydrothermal transition stage is crucial for releasing tin and forming cassiterite during the direct cooling process; (2) fluid-rock interaction between tin-bearing magmatic fluids and carbonates facilitates the precipitation of cassiterite. The small variation in δ11B values for all types of tourmaline (-14.8 to −11.6 ‰) suggests that B-rich fluids are mainly derived from magmatic differentiation and fluid exsolution, with insignificant B isotopic fractionation. Magmatic-hydrothermal evolution at the Xianghualing Sn-polymetallic deposit can be unraveled by using the element and B-isotope fingerprints of tourmaline, which might be used as a prospecting aid for Sn-polymetallic deposits.

Enhanced electrical transport properties of polycrystalline La0.67Sr Ca0.23-K0.1MnO3 ceramics through A-site multielement co-doping

Current research on perovskite materials is mainly focused on how to achieve a high temperature coefficient of resistivity (TCR) in anticipation of application in infrared detection. In this study, we report the superior electrical transport properties of polycrystalline La0.67SrxCa0.23-xK0.1MnO3 (LSCKMO) (0.03 ≤ x ≤ 0.13) ceramics produced through the sol-gel process using different Sr doping contents. Based on previous studies, polycrystalline manganite ceramics with a higher TCR at room temperature were obtained by optimising the composition ratio of Sr or Ca. In the process of continuous doping, the crystal structure of the polycrystalline LSCKMO ceramics changed significantly from Pnma to R 3‾ c. The final polycrystalline La0.67Sr0.10Ca0.13K0.1MnO3 ceramic material was obtained with a TCR of 17.16% K-1 and peak TCR temperature of 289.42 K, demonstrating that suitable candidates can be obtained for infrared detection technology.

Effect of organic solvents on calcium minodronate crystal morphology in aqueous solution: an experimental and theoretical study.

The influence of nine organic solvents on the crystal morphology of calcium minodronate (Ca(Min)2) was investigated by experimental investigations and molecular simulations. Hirshfeld analysis was used to reveal the intermolecular interactions, and the modified attachment energy (AE) model was applied to constructing the Ca(Min)2-organic-water model in different organic-water solvents. The surface structure and the mass density profile were demonstrated and analyzed. The results showed that there were different adsorption conditions in different organic-water solvents. Furthermore, it was found that the (2 0 0)/(1 1 0) side ratio of Ca(Min)2 crystal had a linear relationship with the volume of organic solvent and had a certain correlation with some solvent properties. It is believed that the research developed in this work could have a promising application in prediction of Ca(Min)2 crystal morphology and could give guidance in the selection of organic solvents to control the desirable crystal morphology.

Geochemistry, Depositional Environment, and Provenance of the Cretaceous Radiolarian Chert in Northeastern Kurdistan, Iraq

The radiolarian chert rocks are one of the most important indications of the existence of ophiolites because they are a source of silica supply. These rocks have been studied to refute and reject the idea that ophiolites do not existed. The Si/(Si+Al+Fe+Ca) ratio in the radiolarian chert indicates that the silica is of biogenic origin and adds SiO2 from the shale fraction through diagenetic processes. The high values of Fe2O3 content indicate the hydrothermal effect during precipitation. This effect is controlled by the distance between the sediments and the mid-oceanic ridge or sea floor metamorphism. The phosphorus could be a direct result of volcanic activity associated with ophiolitic rocks, whereas, the negative correlation coefficient of phosphorous with calcium (r = -0.53) supports the idea that the source of phosphorous is volcanic activity that is not related to the carbonate fluorapatite mineral. REEs shows a basic difference as a positive cerium anomaly in section Q2 and a negative cerium anomaly in section Q1. The Al-Fe-Mn diagram shows that all samples fall into the field I non-hydrothermal zone, but in the SiO2 vs Al2O3 diagram the samples of the Q1 section fall into the hydrothermal field, and samples of the Q2 section fall into the non-hydrothermal field. The input materials in Qulqula radiolarian chert come from terrigenous sediments in both sections. On the other hand, the Al/(Al+Fe+Mn) ratio range, (between 0.61 to 0.70), is very close to the average shale composite value, (0.6.19), which may reflect the contribution from continental and non-hydrothermal sediments, while the lower values of this ratio reflect hydrothermal source input. The MnO2 /TiO2 ratios ranged between 0.06 to 2.37 in section Q1 which represents typical characteristics of the deep ocean, trenches, and basaltic plateau sediments.

Cations-Base Application in Rubber Plantation: The Change of Calcium, Magnesium, and Potassium Status in the Soil and Leaves and Its Relation to Latex Yield

Nutrient balance in the soil support plant growth and yield. The objective of this study was aimed to obtain doses of calcium, magnesium, and potassium fertilizers in relation to the ratio of cations-base (Ca2+, Mg2+, K+) to increase latex yield in rubber plants. The study was conducted on a rubber plantation in Dolok Masihul Sub-district, Serdang Bedagai District, North Sumatra, Indonesia, from January to August 2019. The treatment was used with three factors, including the first factor was CaCO3 (0; 1 500 g/tree/year), the second factor of MgSO4.H2O (0; 1 500; 3 000; 4 500 g/tree/year), and the third factor by KCl (0; 500; 1 000; 1 500 g/tree/year) in a Randomized Block Design (RBD) within three replicates. Results showed that the calcium of 1 500 g/tree/year increased the Mg-latex and latex yield by 160.70 g/tree/tapping. An increase in the three cations-base in soil, leaves, latex, and latex yield was also observed after the application of magnesium ranged by 1 500 to 4 500 g/tree/year. The potassium 500 - 1 500 g/tree/year increased the cations-base in soil, latex, and Ca-leaves. The interaction of calcium 1 500 + magnesium 1 500 - 4 500 and potassium 0-1 500 g/tree/year increased the exchange-K, Mg-latex, and also Mg- and K-leaves. The ratio of Ca:Mg:K in soil, leaves, and latex were 2: 1: 2 (optimum), 5: 1: 11 (high), and 1: 11: 32. The Ca, Mg, K in leaves and K-latex positively correlates and increases latex yield due to the three fertilizations.

Purification of Si–Ti alloys via vacuum evaporation: A thermodynamic and kinetic study of Ca impurity removal

Vacuum refining is a green technology for separating Ca from Si–Ti alloys. This study investigated the kinetics of Ca evaporation from Si–Ti melts in vacuum refining, including the effect of holding time and melt temperature and composition. Although the Ca activity in Si–Ti melts is an essential thermodynamic property that affects the Ca evaporation kinetics, it has not been measured to date. Consequently, another objective of this study was to determine the Ca activity using a chemical equilibration technique and investigate its effect on Ca evaporation. The results show that the activity of Ca in the Si–Ti melt decreased gradually with increasing Ti content in the melt, which reduced the Ca removal ratio. The removal ratio of Ca increased with the temperature and holding time. The apparent evaporation rate of Ca was consistent with the first-order law, and the apparent evaporation rate constants of Ca in 15%Si–Ti melt at 1673 and 1773 K were 2.1 × 10−6 and 2.8 × 10−6 m/s, respectively. The apparent activation energy for Ca evaporation from Si–15 wt%Ti melt was determined to be 68.2 kJ/mol, and the rate-determining step to be Ca mass transfer at the melt boundary layer.

Concerning the incorporation of potassium in the crystal structure of combeite (Na2Ca2Si3O9)

Potassium incorporation in the structure of combeite has been studied in detail. Since natural combeites are known to contain only small amounts of potassium focus was laid on the Na-rich part of a hypothetical solid-solution series with composition Na2-xKxCa2Si3O9. Samples were prepared from mixtures of silica and the corresponding carbonates for nominal compositions with x = 0.2, 0.3 and 0.5, heated from ambient temperature to 1350 °C and slowly cooled to 1000 °C. After disintegration of the carbonates, the platinum capsules used as sample containers were welded shut in order to avoid losses of the volatile K2O and Na2O components. From all three batches potassium containing combeite crystals could be retrieved. Single-crystal diffraction experiments revealed the following compositions: Na2.10(1)K0.11(1)Ca1.90(1)Si3O9, Na2.09(1)K0.18(1)Ca1.91(1)Si3O9 and Na2.13(1)K0.18(1)Ca1.87(1)Si3O9. Consistently, the trigonal crystals (space group P 31 2 1) contained (i) (K + Na):Ca ratios larger than 1:1 and (ii) potassium concentrations lower than those in the starting mixtures. Since the K-contents of the samples obtained from the runs with x = 0.3 and 0.5 were almost identical, the solid-solution seems to be rather limited with an upper boundary of about one potassium atom per unit cell. The structure of the K-containing combeites is very close to the K-free structures reported in the literature. It can be described as a mixed tetrahedral-octahedral network in which additional K, Na and Ca cations are incorporated for charge compensation. A detailed analysis of the topological features of the net is presented. From the six observed extra-framework sites only the M22 position showing a coordination environment with ten next oxygen neighbours is involved in the K-substitution. Potassium uptake is also reflected in increasing values for the lattice parameters a and c as well as the unit-cell volumes. Actually, the c-axis is more affected from the incorporation of the comparatively large K+-cations.

Calcium-based composites directly irradiated by solar spectrum for thermochemical energy storage

The optical absorptance of calcium-based composites used in direct solar-driven calcium-looping thermochemical energy storage systems should be improved. Experimental data obtained by thermogravimetric analyzer (TGA) cannot adequately describe the realistic performance of such calcium-based composites. In this work, calcium-based composites filled in a fixed bed reactor were directly irradiated by concentrated sunlight to examine the performance of thermochemical energy storage under different light illumination conditions. The effects of doping content and concentration ratio of sunlight on the cycling performance of the modified calcium-based composites were investigated under direct solar-driven conditions. The Cr/Mn co-doped CaCO3-based materials with a molar ratio of Ca: Cr: Mn = 100:4:8 could be efficiently operated under direct sunlight irradiation conditions because of a high optical absorption of 73.22 %, achieving gravimetric energy densities of 1090 and 818 kJ/kg in the 1st and 10th cycles, respectively. The cycling performance of the calcium-based composites under different light illumination conditions was compared with that using the TGA device. By comparing the optimal performance in two operating modes, the cycling stability of the calcium-based composites attenuated faster in the solar-driven fixed bed reactor than in the TGA device, which was ascribed to the uneven temperature distribution in the solar-driven reactor. By preventing surface overheating or localized hot spots in a direct solar-driven reactor, cycling stability of the calcium-based composites can be enhanced. Based on this principle, we propose some improvement methods for ensuring uniform temperature distribution in CaCO3-based composites during the direct solar-driven calcination process.