Calcium Compounds Research Articles

Phenomena and mechanism of slagging and corrosion in energy use of coal with a high content of salts

Purpose. Determination of the main mechanisms of slagging and corrosion of heating surfaces when using coal or other raw materials with a high content of alkali and alkaline earth metals. Experimental determination of mineral phases of ash residues of burning composite raw materials with the participation of salty coal and the influence of component composition on the formation of refractory compounds. Methodology. Critical analysis and generalization of achievements in the developed theories of slagging and corrosion of surfaces during the combustion of problematic carbon raw materials (salty coal, biomass, some wastes, etc.). Determination of the main approaches to the problem of using coal with a high pollution factor. Selection of objects of experimental study on composite raw materials, including coal of different degrees of metamorphism and salinity. Identification of minerals of ash residues of individual fuels and their blends using X-ray phase analysis (X-ray diffraction). Semi-quantitative phase analysis of diffractograms was performed using MATCH! software. Findings. Modern views on the causes of slagging and corrosion processes during the combustion of fuel with a high salt content are highlighted. It has been determined that the process of intensive slagging is associated with a certain ratio of sodium, calcium and iron compounds. The composition and features of the mineral phases of ash residues of composite fuel with the participation of salty coal are experimentally established. The influence of the content of components on the formation of certain mineral phases of mixed ash was determined. Originality. For the first time, the prospects of using two-component blended fuel with the participation of Ukrainian salty coal have been studied. The analysis of minerals in ash residues of salty coal and its blends was carried out. It has been determined that the main part of Na in ash of salty coal of the Bohdanivske deposit in the Northern Donbas is in the form of sulfates and silicates. For the first time, the composition and ways of formation of new refractory mineral compounds in the ash formed during the combustion of composite fuel from coal of different metamorphism and salinity have been established. Practical value. Based on the analysis of literary sources and conducted studies, the dependence of the ash composition on the minerals of the initial fuel and on the ratio of various components in the blends was determined. The proposed approach has a predictive power, as it allows predicting the formation of the main refractory ash minerals. The expediency and prospects of involving salty coal in the fuel base of Ukraine as a component of blended fuels are shown.

Selective Epitaxial Growth of Ca2NH and CaNH Thin Films by Reactive Magnetron Sputtering under Hydrogen Partial Pressure Control.

Calcium compounds with N and H are promising catalysts for NH3 conversion, and their epitaxial thin films provide a platform to quantitatively understand the catalytic activities. Here we report the selective epitaxial growth of Ca2NH and CaNH thin films by controlling the hydrogen partial pressure (PH2) during reactive magnetron sputtering. We find that the hydrogen charge states can be tuned by PH2: Ca2NH containing H- is formed at PH2 < 0.04 Pa, while CaNH containing H+ is formed at PH2 > 0.04 Pa. In situ plasma emission spectroscopy reveals that the intensity of the Ca atomic emission (∼422 nm) decreases as PH2 increases, suggesting that Ca reacts with H2 and N2 to form Ca2NH at lower PH2, whereas at higher PH2, CaHx is first formed on the target surface and then sputtered to produce CaNH. This study provides a novel route to control the hydrogen charge states in Ca-N-H epitaxial thin films.

Formation of Calcium Phosphate Apatite in System CaO-P2O5-H2O: Equilibrium at 298 K Under a Nitrogen Atmosphere

Aims: The formation of calcium phosphate apatite (hydroxyapatite, carbonate-containing hydroxyapatite, fluorapatite and carbonate-containing fluorapatite) in aqueous systems has been studied for over a century. Background: However, in the region of low concentrations of liquid phases, the question of the nature, composition and region of existence of apatite compounds remains controversial. Objective: The results of studying the phase equilibrium in the system CaO-P2O5-H2O at 298 K in the isotherm region from the invariant point of dicalcium phosphate and monocalcium phosphate monohydrate to the lowest concentrations of the liquid phase components are presented. Method: Chemical analysis, thermogravimetry, IR spectroscopy and optical microscopy were used for the analysis. Result: Long-term monitoring of the establishment of equilibrium (up to 20 months) resulted in the determination of regions of stable solid phases of calcium orthophosphates, calcium-deficient apatites, hydroxyapatite, and apatite with (Ca/P)at &gt;1.67. Two types of calcium-deficient apatite were identified that differ in the (Ca/P)at ratio: the first type is 1.33 &lt; (Ca/P)at ≤ 1.5; the second one is 1.5 ≤ (Ca/P)at &lt; 1.67. Conclusion: The invariant points of calcium orthophosphates and compounds with the apatite structure were determined. The diagram was constructed using the Miller-Kenrick method based on obtained experimental data, which confirms the established regions and invariant points of stable equilibrium solid phases of the studied ternary system. The data obtained can be useful for understanding the processes of formation and change of compounds with apatite structure.

Calcium release-mediated adsorption and lubrication of salivary proteins on resin-based dental composites

The lack of wear resistance is always a challenge for clinical applications of resin-based dental composites (RBDCs). In this study, the role of the calcium release from RBDCs in the adsorption and lubrication of salivary proteins was investigated, aiming to provide useful insights concerning the development of high-performance RBDCs. Three experimental RBDCs with distinct calcium-releasing capabilities were prepared using calcium phosphate particles as inorganic fillers. Salivary protein adsorption and film-forming on RBDC surfaces were characterized by atomic force microscopy, while the mechanical properties and lubricating effect of salivary pellicle were examined using nano-indentation/scratch techniques. Results showed that calcium release from RBDCs plays a crucial role in mediating the electrostatic interaction between salivary proteins and composite surface, thereby promoting the formation of salivary pellicle with a multi-layer structure. The mechanical properties and lubricating effect of the pellicle are positively related to the level of calcium release. In sum, for RBDCs with robust calcium release, saliva provides effective lubrication to resist composite wear. Incorporating calcium compounds is a promising way to improve the wear resistance of RBDCs in the oral cavity.

Preparation of polyvinyl alcohol-calcium sustained-release agent employed to degrade long-chain fatty acids and improve the performance of anaerobic digestion of food waste

Polyvinyl alcohol (PVA) is a biodegradable material that can be degraded under natural conditions. In this study, a sustained-release agent (SRA) was prepared from calcium compounds and PVA (PVA-Ca) to effectively degrade long-chain fatty acids in food waste (FW) and improve the performance of anaerobic digestion (AD). The most appropriate materials and conditions for synthesizing Ca-SRA were chosen according to the characteristics of the sample and changes in the electrical conductivity of a solution of the SRA. The calcium release kinetics were analyzed by curve fitting. Moreover, analytical methods were used to analyze the formation mechanism of PVA-Ca. Finally, the effect of PVA-Ca on the performance of AD was investigated. The results showed that the most suitable materials for preparing the Ca-SRA were Ca(OH)2 powder and PVA1799. The most suitable synthesis conditions were freezing for 24 h at −20 °C and thawing for 24 h with one freeze–thaw cycle. PVA-Ca achieved rapid release during the first 48 h, which corresponded to first-order kinetics (k = 0.0354 h−1). The release of Ca2+ corresponded to changes in pH and the concentration of volatile fatty acids during hydrolysis and acidification of FW. After PVA-Ca was added, the duration of the system lag phase was significantly shortened to 10 days, the methane yield per unit load was increased from 238.2 to 489.3 mL g−1 volatile solids(VS), and the kinetic constant of AD of FW was 0.083 day−1. Adding PVA-Ca could increase the methane yield by 98.82%. Moreover, the value of T90 was reduced to a maximum of about 16 days. PVA-Ca was successfully employed in the AD of FW for the first time.

The Role of Chitosan-Silver Nitrate Nano Gel to improve the Desensitization of Dentine Hypersensitivity

Dentine hypersensitivity is a short and sharp pain from exposed dentine in response to thermal changes, tactile stimulation, osmotic and chemical stimulation. Chitosan is reportedly capable of closing the dentinal tubules to prevent hypersensitivity resulting from pain stimulation. The study aimed to evaluate the ability of nano chitosan silver nitrate in the desensitization of dentinal tubular hypersensitivity. A total of 24 odontectomy third molars were divided into three groups: control, nano chitosan-silver nitrate, and varnish gel (5% sodium fluoride -tricalcium phosphate). Next, the dentinal tubules are examined by SEM, and EDS analyzes the chemical elements. The three test materials' ionic properties were reviewed with a conductivity meter, while the viscosity used a viscometer. Chitosan-silver nitrate gel showed a better ability to close dentine tubules than varnish gel at intervals of 24 and 48 hours (p&gt;0.05). Chitosan can increase calcium compounds in closing dentine tubules than varnish gel, particularly at 48 hours. Furthermore, both chitosan's conductivity and oxygen solubility values were higher than the varnish gel.: Chitosan has a high intensity in closing the dentinal tubules in in-vitro studies of dentine hypersensitivity, which correlates with increased calcium on dentine's surface by showing better solubility ionic conductivity and oxygen dissolves.

Effects of Nutrient Elements on Growth and Expression of Insect-Defense Response Genes in Zanthoxylum bungeanum Maxim

In China, Zanthoxylum bungeanum Maxim, known as “Huajiao,” has a pleasant, fragrant flavor and several therapeutic properties. The nutritional content of plants is necessary for their defense response to insects. In this study, we analyzed the effects of soil fertilization treatments such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and special compound fertilizer for pepper (HZ) on the different growth parameters and expression of insect-defense-response genes in Z. bungeanum. The results show that the height and weight of prickly ash significantly differed after the application of fertilizers with different concentrations. Additionally, seedlings that were treated with low concentrations of nutrient fertilizers (N1, P1, K1, Ca1, and HZ1) were significantly higher, and they were selected for transcriptome analysis. According to transcriptomic analysis, a total of 65,566 unigenes were discovered, among which 61,379 corresponded to annotated protein-coding genes and 4187 to transcripts of novel protein-coding genes. A total of 294 unigenes were detected as candidate genes for regulating the defense response to insects, including 204 protease inhibitors, 29 plant lectins, and 61 other defense response genes. Additionally, trypsin inhibitors, cystatin, phytepsin, metalloproteinase, MMP, caffeic acid, resveratrol, and thiol proteinase inhibitors, ACA, TDC, and 28 BES1 were enriched in Z. bungeanum. Specifically, the leaves of Z. bungeanum that were treated with Ca and HZ fertilizations were dominated by the protease inhibitors. In addition, the type of fertilizer significantly affects gene expression in plants. The functional annotations were predicted by the number of differentially expressed genes and classified by GO and KEGG ontology enrichment analysis. Moreover, according to the GO database, biological processes were the largest group and contained a high frequency of differentially expressed genes. According to KEGG pathway results, significantly enriched genes belonged to the biosynthesis of secondary metabolisms, amino acid metabolism, and folding, sorting, and degradation. Overall, it was found that the type of fertilizer with low concentrations had an effect on Z. bungeanum’s primary and secondary metabolism, and these findings provided grounds for further research in forest protection science.

Application of Calcium Citrate in the Manufacture of Acid Rennet Cheese Produced from High-Heat-Treated Goat's Milk from Spring and Autumn Season.

The stability of milk proteins is affected by changes in the pH value of milk, the heating temperature, and the addition of calcium compounds or chelating agents, which can cause alterations in calcium distribution. The purpose of this study was to determine the potential of the use of calcium citrate to manufacture fresh acid rennet cheese from high-temperature-pasteurized goat’s milk (90 °C, 15 s) from the spring and autumn season and the effect of the calcium dose used on the physicochemical and organoleptic properties of the cheese. Autumn milk was found to be a richer source of total solids, confirming the effect of the production season on milk quality. The applied doses of calcium did not cause the denaturation of goat milk proteins and allowed pasteurization to take place at 90 °C for 15 s. The addition of calcium citrate resulted in a significant increase in the pH value of milk and cheese compared to the control sample. Adding 15 and 20 mg of Ca 100 g−1 to milk as citrate had the most beneficial effect on increasing protein retention in cheese in both seasons, showing a rise from 1.33% to 2.40%. The production season significantly influenced the cheese yield. The control goat cheese from the autumn season showed a 6.85% higher yield compared to the spring cheese. An increase in cheese yield was also observed as the calcium dose of milk increased. The content of micro- and microelements in cheese was affected by the production season. The addition of calcium citrate to milk resulted in a significant increase in the calcium content of cheese—from 120.83 to 147.45 mg 100 g−1 in the spring season and from 130.66 to 151.21 mg 100 g−1 in the autumn season. Increasing the dose of calcium increased the hardness of cheese samples by 1.37 N in the spring and 0.90 N in the autumn. The organoleptic evaluation showed that adding calcium to milk did not significantly affect the organoleptic characteristics of goat cheese.

Cover Feature: Synthesis, Structure, and Spectroscopic Properties of Calcium Thiophenecarboxylate Polymers. Structural Comparison with Analogous Lead Complexes (Eur. J. Inorg. Chem. 29/2022)

The Cover Feature shows a fragment of the selected calcium(II) thiophene-2-carboxylate coordination polymer (CaCPs) against the background of the obtained monocrystals. The selected polymer has a one-dimensional crystal structure described by the (4,4)(0,2) topology. Changing the position of the carboxylate group in the thiophene ring as well as extending the linker by −CH2 in the ligand do not change the dimensionality and topology of the obtained calcium polymers. Interestingly, the change of ligand affects the luminescence properties of the calcium polymers. The calcium compound was compared with the lead(II) polymer (PbCPs) to highlight similarities and differences of the two polymers and thus the coordination preferences of both ions. This part of the work demonstrates the possibility of substituting lead ions by calcium ions in biological systems based on structural comparison. More information can be found in the Research Article by J. Masternak and co-workers.

The Effect of a New N-hetero Cycle Derivative on Behavior and Inflammation against the Background of Ischemic Stroke.

Ischemic stroke triggers a whole cascade of pathological changes in the brain, one of which is postischemic inflammation. Since in such cases thrombolytic therapy is often not possible, methods that modulate inflammation and affect microglia become particularly interesting. We synthesized 3-(2-oxo-4-phenylpyrrolidin-1-yl)propane-1-sulfonate calcium(II) (Compound 4) and studied its anti-inflammatory activity in in vitro and in vivo models of inflammation and ischemia. Macrophage cell line RAW 264.7 was treated with lipopolysaccharides (LPS) and Compound 4 at various dosages to study the cytokine profile using real-time PCR and cytometric bead array (CBA). Stroke in rats was simulated by the middle cerebral artery occlusion method (MCAO). Several tests were performed to characterize the neurological deficit and locomotor activity of the rats, and afterwards, postmortem, the number of astrocytes was counted using immunohistochemistry. Compound 4 in in vitro tests dose-dependently reduced the expression of interleukin-1β (IL1β), and inducible nitric oxide synthase (iNOS) genes in cell culture and increased the concentration of cytokines: interleukin-2, 4, 6 (IL-2, IL-4, and IL-6). In vivo Compound 4 increased the orienting-exploratory behavior, and reduced neurological and motor deficit. The number of astrocytes that promote and support inflammation was lower in the group treated with Compound 4. The stroke volume measured by magnetic resonance imaging (MRI) showed no difference. We have shown that Compound 4 demonstrates anti-inflammatory activity by increasing the synthesis of anti-inflammatory and reducing pro-inflammatory cytokines, and positively affects the neurological deficit in rats. Thus, Compound 4 has a high therapeutic potential in the management of patients after a stroke and requires further study of its neuroprotective properties.

MAIN TRENDS AND DIFFERENCES IN THE COMPLEX FORMATION OF AMINO ACIDS WITH CALCIUM(II) AND MAGNESIUM(II) IONS ACCORDING TO OPTICAL SPECTROSCOPY DATA

The thermodynamic stability constants of coordination compounds of calcium(II) and magnesium(II) ions with amino acids in aqueous solutions at 298 K were calculated by spectrophotometry using the mathematical processing of experimental data. The main principles and approaches of mathematical processing are shown. Differences of calcium(II) and magnesium(II) ions as complexing amino acids as ligands are indicated, a regularity in the complex formation of amino acids of various structures is established.

Effect of citric acid erosion on enamel and dentin and possible protection by a novel bioactive borate adhesive system

ObjectivesThis study examined the ability of a borate adhesive to protect enamel/dentin surfaces from acidic erosion and its effect on the shear bond strength (SBS) of enamel/dentin to resin composite. Materials and methods180 human enamel/dentin specimens were utilized. Enamel buccal surfaces were etched with phosphoric-acid then divided into: (EBG) borate glass adhesive group; (ERS) resin-adhesive system group; (EF) fluoride gel 1.23% group, and enamel control (EC) group; followed by bonding to orthodontic-buttons. The dentin specimens were conditioned by EDTA (Ethylene-diamine-tetra-acetic acid) and divided into: (DBG) borate glass resin, (DRS) resin adhesive; (DDA) group had a dentin-desensitizing agent VivaSens (VivaDent, Liechtenstein) and (DC) control group. The treated enamel/dentin specimens had their SBS to composite. The enamel/dentin specimens were exposed to 1% citric acid (18 min). Enamel/dentin specimens were examined by (SEM/EDS) scanning-electron-microscope equipped with electron-dispersive-spectroscopy and (FTIR/ATR). Analysis-of-Variance (ANOVA) was used to compare the SBS and Wilcoxon-signed-rank test was used to compare the enamel/dentin areas protected by the applied agents before/after erosion (p = 0.05). ResultsThere was no significance difference in SBS among all groups except for (DDA) group that showed significant decrease p < 0.05. (EBG) and (DBG) groups were the only groups significantly protected enamel and dentin from erosion p < 0.05. FTIR/ATR showed that erosion altered the chemical structure of (DRS), (DDA), and (DC) groups but did not affect the other enamel/dentin groups. Degree of conversion of the borate-adhesive system was acceptable. ConclusionThe Borate adhesive system released calcium and phosphate compounds that decreased the erosive activity of the citric acid resulting in protecting simulated dentin-hypersensitive areas and enamel from erosion without affecting the SBS to resin-composite. Clinical significanceA Borate adhesive system can be adopted as a therapeutic agent in a fully integrated program for protecting dentin-hypersensitive areas and in enamel next to orthodontic fixed appliances.

Kajian penambahan serbuk pegagan (Centella asiatica) terhadap mutu cookies tepung mocaf (modified cassava flour)

Cookies are a type of biscuit made from wheat flour with a soft dough, high fat content, relatively crunchy, and dense texture. To increase the nutritional value and functional properties of cookies, it is necessary to add other ingredients such as pegagan plant. The pegagan plant contains chemical components that are good for human health such as calcium, ascorbic acid, and bioactive compounds such as triterpenoids and asiaticoside which have antioxidant activity. The purpose of this study was to determine the effect of the addition of pegagan powder on the quality of mocaf flour cookies and determine the percentage of addition of pegagan powder that was appropriate and preferred by the panelists. The method used in this study was an experimental method arranged in a completely randomized design with the addition of pegagan powder in the manufacture of cookies consisting of five treatments: P0 (100% mocaf flour/control), P1 (2.5% pegagan powder), P2 (5% pegagan powder), P3 (7.5% pegagan powder) and P4 (10% pegagan powder). The results of the measurement of chemical properties and organoleptic tests were analyzed using a further test of Honest Significant Difference at 5% level. Based on the results of the study, it was found that the addition of pegagan powder had a significant effect on all tested chemical properties (moisture content, ash content, vitamin C, and antioxidant activity) and also on taste, aroma, and color scores, but had no significant effect on cookies texture scores. In which, the higher the concentration of pegagan powder added, the water content, ash content, vitamin C content, and antioxidant activity increased, while the scores for aroma, taste and color tended to decrease. The best treatment favored by panelists was P3, with preferred taste, slightly favorable aroma, green appearance color, and slightly soft texture. The values of water content, ash content, vitamin C content, and P3 antioxidant activity were 8.36%; 3.08%; 0.38%; and 94.45%, respectively.

Study of the effect of matrix components of natural mineral water on the determination of dissolved forms of silicon by high-resolution electrothermal atomic absorption spectrometry with a continuous spectrum source

The influence of the mineral composition of water on the results of silicon determination by high-resolution atomic absorption spectrometry with a continuous spectrum source (HR-CS-ETAAS) and electrothermal atomization technique using a contrAA 700 spectrometer has been studied. The study was conducted using samples of natural water from different regions of the Russian Federation and model solutions. A low degree of silicon atomization was recorded when analyzing samples with a complex matrix against the background of a strong absorption signal of matrix components. The reason for the non-selective absorption of the sample matrix by chemical compounds has been demonstrated using a water sample with the most complex composition and a total hardness of about 2000 °dH. The effect of soluble salts of Ca (II) and Mg (II) in the presence of macrocomponents — alkali metal ions K (I) and Na(I) — on the determination of silicon in water has been proved. It is shown that at the values of the total stiffness less than 15 °dH there is no dependence of the analytical signal on the content of matrix components. An assumption is made about the strong influence of calcium compounds on the determination of the analyte due to the formation of a carbide coating on the surface of a graphite furnace, the appearance of a «memory effect» and an increase in the background signal during subsequent atomization cycles. The best results of the silicon determination were obtained with tungsten, iron, magnesium, and palladium present as chemical modifiers. A method of diluting the sample solution was used to reduce the level of background absorption during electrothermal atomization of mineral water. Conditions for eliminating the influence of matrix components for real samples of mineral water and calibration solutions are proposed. A method for determination of the dissolved forms of silicon in water samples with a complex matrix has been developed. The correctness of the results of silicon determination in the samples of natural underground water in the case of a strong matrix effect was confirmed by an independent method of analysis. The results of the study reveal the entirely new prospects of using the method of high-resolution electrothermal atomic absorption spectrometry with a continuous spectrum source for the determination of silicon in natural water.

Behaviour of strain hardening geopolymer composites at elevated temperatures

Strain hardening geopolymer composite (SHGC) is a sustainable fibre-reinforced material that exhibits superior strain-hardening and multiple cracking behaviour under tension. The geopolymer binder synthesised through alkali-activation of aluminosilicate precursors sourced from industrial by-products is chemically stable at elevated temperatures. This paper presents a systematic experimental study on behaviour of fly ash-slag based SHGC reinforced with polyvinyl alcohol (PVA) fibres exposed to elevated temperatures up to 800 °C through weight loss, uniaxial compressive, ultrasonic pulse velocity (UPV) and uniaxial tensile tests as well as thermal analysis using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and derivative thermogravimetry (DTG), X-ray diffraction (XRD), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP). Results indicate that the compressive strength of SHGC is increased until exposure to 250 °C, followed by a decline up to 600 °C and a regain at 800 °C. The strength gain mechanisms include further geopolymerisation that refines the microstructure, fibre bridging action and sintering that densifies the binder gels, while the strength reduction can be attributed to the damage induced by internal moisture removals and evaporation of fibres, decomposition of calcium compounds, and empty channels introduced by vanished fibres. Besides, the SHGC specimens exposed up to 250 °C exhibit high ductility performance with saturated microcracks when subjected to uniaxial tension, whilst those at 105 °C demonstrate the best strain-hardening degree because of the desired fibre-matrix interaction and enhanced matrix strength. Moreover, no spalling can be observed in SHGC due to its relatively porous structure.

Surface Modification of Synthetic Zeolites with Ca and HDTMA Compounds with Determination of Their Phytoavailability and Comparison of CEC and AEC Parameters.

Zeolites obtained from fly ash are characterized by very good anion- and cation-exchange properties and a developed porous structure. This paper presents the results of surface modification studies of synthetic zeolites obtained from calcined coal shale (clay materials). Calcium compounds and hexadecyltrimethylammonium bromide (HDTMA) were used as modifying substances. The characteristics of the raw material and the zeolite obtained as a result of its synthesis are presented. The surface modification method is described. Furthermore, the results of sorption and desorption of NO3, PO4, and SO4 from raw and modified samples are presented. The results of anion- and cation-exchange capacities for other zeolite types were also compared. Modification of the materials with Ca ions and HDTMA surfactant only improved the sorption of sulfates. The 90% desorption of nitrates, phosphates, and sulphates from the zeolite material without modification indicates a good release capacity of these compounds and their potential use as fertilizer additives.

Too much of a good thing: A case series of rare yet pertinent causes of hypercalcaemia and acute kidney injury.

Calcium compounds and vitamin D supplements are readily available as over-the-counter preparations. Whilst integral in maintaining calcium homeostasis in certain patients, excess exogenous intake of these preparations can have deleterious effects, particularly in terms of renal function. We look at the cases of two patients, aged 52 and 34, who were referred into hospital with hypercalcaemia and acute kidney injury (AKI). Both individuals reported regular and prolonged self-medication with unregulated over-the-counter supplements containing calcium carbonate and vitamin D, respectively. Prompt investigation and treatment enabled an element of reversibility of the AKI in both the cases, with further improvement in renal function over time. We emphasise the importance of recognising the overuse of exogenous vitamin D supplements and calcium compounds as rare yet treatable causes of AKI associated with hypercalcaemia and discuss how raising public awareness into the risks posed by self-medication of over-the-counter medicines is paramount.

Aceh Local Dolomite Modified by Alkali Metals as a Low-Cost Solid Inorganic Catalyst for Biodiesel Synthesis

Solid inorganic-based catalyst which mainly contains calcium oxide and magnesium oxide has been successfully prepared from local Aceh dolomite minerals. The calcination process of dolomite particles (150 μm) in the air environment for 4 hours changed those calcium and magnesium carbonates compounds into their oxide form, which are subsequently referred to as inorganic oxides. Furthermore, the calcined local dolomite has been chemically modified using alkaline metal precursors (lithium, sodium and cesium precursors). Physicochemical investigation on the modified dolomite indicated that introduction of lithium metal on modified dolomite surface has a positive impact on increasing the number and strength of basic sites on the catalyst. The modified catalyst had proved its catalytic activity for biodiesel synthesis with the yield values of 82;78;51 respectively.

Characterization and comparison of gasification and incineration fly ashes generated from municipal solid waste in Singapore

Slagging-gasification has received increasing attention as a municipal solid waste treatment technology. Compared with incineration, slagging-gasification can produce valuable syngas and generates by-products that can be easier reusable in different applications in some cases. Among these by-products, the gasification fly ash (GFA) is the only hazardous solid residue to be landfilled. To explore its potential recycling methods and maximize its recycling efficiency, the detailed physicochemical properties of GFA are crucial. This study conducted a comprehensive characterization of six GFA samples and the results were compared with one incineration fly ash (IFA) sample and available data of IFA collected in Singapore in literature. X-ray fluorescence (XRF), and microwave acid digestion (MAD) followed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectroscopy (ICP-MS) were carried out to determine the physicochemical composition of ashes. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were applied to identify their mineralogical composition. The hazard of the material was assessed through one-stage batch leaching tests. The results showed that the GFAs and IFA were both mainly composed of calcium compounds and chloride salts. However, GFA contained higher amounts of heavy metals especially lead (Pb) and zinc (Zn) than IFA. Zn contents in tested GFA samples were in a range of 1.4–3.0%, indicating the potential to recover Zn. The Ca(OH)2 content in GFA samples was up to 24.1%, which could be recovered as a low-grade lime. Based on the characteristics of GFA, a reusing method combining civil engineering utilization and resource recovery was suggested.

Management of Tomato Yellow Leaf Curl Virus (TYLCV) Infecting Tomato by using Calcium Rich Compounds

Bemisia tabaci (whitefly) transferred Tomato yellow leaf curl virus (TYLCV) disease is a significant constraint on tomato productivity. One technique for managing the condition is to spray calcium compounds (calcium carbonate, calcium chloride, calcium nitrate) onto tomatoes. According to the research findings, the incidence of TYLCV was lower in calcium compound sprayed plants than in control plants. The control group had the greatest TYLCV prevalence. Calcium carbonate-treated plants had the lowest TYLCV, followed by calcium nitrate-treated plants. Temperature and relative humidity were shown to be strongly linked with the population of whiteflies, the TYLCV vector in the tomato field. The expansion of TYLCV in tomatoes and the growth in whitefly populations were shown to have positive and substantial connections. In terms of plant height, fresh shoot weight, dried shoot weight, and root length, the three calcium compounds outperformed the others. Furthermore, the number of fruit/plants in the calcium carbonate spray was shown to be higher than in the control. With a few exceptions, calcium carbonate and calcium nitrate treatments were shown to be superior to calcium chloride treatments in terms of increasing growth and yield, contributing to character as well as yield.