Ca Compounds Research Articles

Theoretical investigation of structural, electronic, mechanical, surface work function and thermodynamic properties of La1-xMxB6 (M = Ba, Sr, Ca) compounds: Potential plasma grid materials in N-NBI system

This study employs first-principles calculations to investigate the structural, electronic, and mechanical properties of La1-xMxB6 (M = Ba, Sr, Ca), focusing on the surface work function, elastic constants, bulk modulus, shear modulus, Young’s modulus, Debye temperature, and melting point. The results indicate that doping generally leads to a reduction in the surface work function, with La0.375Ba0.625B6 achieving a work function as low as 1.27 eV. The influence of doping concentration on the mechanical properties and anisotropy is analyzed, revealing that La1-xMxB6 and La0.5Sr0.5B6 exhibit oscillatory changes related to the layered structure of the dopants. Brittleness is assessed through the B/G ratio and Poisson’s ratio. Thermodynamic analysis shows that the melting points of these compounds exceed 2000 K. These findings provide useful references for choosing cesium-free electrode materials applied for plasma-facing applications in neutral beam injection.

Hydrolytic instability of laser-ablatively deposited CaSi2 coatings in air and neutral water affects the behavior of bone healing-related cell types

Calcium silicide (CaSi2) instability in humid air or pH-neutral water remains unknown, although the topochemical formation of silicene from CaSi2 in various aqueous phases is a well-known process. Here we report on laser ablation of CaSi2 in the vacuum and ethanol, characterize coatings deposited on titanium substrates with electron microscopy, X-ray photoelectron, Raman, and infrared spectroscopy, and examine the instability of the deposited coatings in humid air and neutral water. We further investigate the behavior of human mesenchymal stromal cells (hMSCs), vascular cells (HUVECS, human umbilical vein endothelial cells), and macrophages (derived from THP-1 cell line) in contact with the deposited coatings submerged in cell culture medium. The observed results indicate that the CaSi2 coatings undergo topochemical conversion to silicene, which is accompanied by hydrolytic reactions leading to inorganic Ca compounds and SiO2, and that the response of all cell types in the hydrolyzed CaSi2 surface domain is negatively affected by the nature of the hydrolytic products. In contrast, cells showed a tendency for enhanced biocompatibility towards the CaSi2 particles ablated in the vacuum. The results suggest that coating approaches can significantly influence cell behavior outcomes.

Computational analysis of the X2H3I (X=Ca or Sr) compounds for hydrogen storage: A DFT approach

Computational analysis of the X2H3I (X=Ca or Sr) compounds for hydrogen storage: A DFT approach

Structural stability, optoelectronic, thermoelectric, and elastic characteristics of X2ScBiO6 (X= Mg, Ca, and Ba) double perovskites for energy harvesting: First-principles analysis

Double perovskites have emerged as a potential new material for optoelectronic and thermoelectric applications. We explored structural, electronic, optical, thermoelectric, and elastic properties of double oxides perovskite, X2ScBiO6 (X = Mg, Ca, and Ba) through density functional theory (DFT). The most stable structure, according to the optimized structural parameters, is a cubic Fm3m (225) symmetry with a nonmagnetic (NM) state. We have utilized TB-mBJ to estimate the band structure and density of states. The semiconductor nature is predicted with indirect bandgap values of 1.90 eV, 1.39 eV, and 1.11 eV for Mg2ScBiO6, Ca2ScBiO6, and Ba2ScBiO6, respectively. Notable optical responses such as higher absorption (>105 cm−1) and low reflectivity for X2ScBiO6 suggest appropriate candidates for optoelectronic device applications. The efficient thermoelectric order has been investigated under semiclassical Boltzmann theory and constant relaxation time approximation as implemented in the BoltzTraP (BT) code. Several parameters, such as the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor, and figure of merit, have been calculated. The ductile character of the X2ScBiO6 (X = Mg, Ca, and Ba) compounds is further supported by the elastic properties. Consequently, the results show that the compounds investigated could be good alternatives for thermoelectric and photovoltaic applications.

Study of the physical properties of the half-heusler XBrH with (X= sr, Ca and mg) compounds

Half-Heusler alloys are among the most promising thermoelectric materials for medium- and high-temperature waste heat recovery applications. This study investigates the physical properties of Half-Heusler compounds XBrH, with X = Sr, Ca, and Mg. We explored the structural, electronic, optical, and thermoelectric properties of these compounds using density functional theory (DFT) as implemented in the Wien2k package. The Generalized Gradient Approximation (GGA) as proposed by Perdew-Burke-Ernzerhof (PBE) and the modified Becke-Johnson (mBJ) functional were employed to calculate the exchange-correlation interactions. After doing structural optimization for a range of parameters, we discovered that the SrBrH compound is more stable than the CaBrH and MgBrH compounds. Our results show that the density of state calculations indicate semiconductor behavior for the XBrH with (X = Sr, Ca, and Mg) compounds. We also evaluated the real and imaginary parts of the dielectric tensor, the refractive index, the absorption coefficient, the electron energy loss, and the real and imaginary components of the optical conductivity, among other optical parameters. Additionally, we investigated the figure of merit (ZT), electronic and lattice thermal conductivity, Seebeck coefficient, and electrical conductivity. The MgBrH, CaBrH and SrBrH compounds showed p-type behavior, with positive values for the Seebeck coefficient and the greatest value of ≈180 μV/K, according to the thermoelectric data. At 1000 K, the ZT reach their highest values for CaBrH, SrBrH, and MgBrH, respectively, at 2.9, 2.8, and 0.9. The physical properties of the XBrH with (X = Sr, Ca, and Mg) compounds have been studied in detail.

Pre-harvest foliar spraying of calcium and zinc preserves berries quality and mitigates chilling injury of grape during cold storage

The current study was conducted to elucidate the effect of single and combined post-veraison sprays of calcium nitrate (Ca, 2 %) and zinc sulfate (Zn, 1 %) on post-harvest quality attributes of ‘Sahebi’ grapes during cold storage. Grapes foliar-sprayed with combination of Ca and Zn showed higher flavonols (28 % myricetin, 4 % quercetin, and 15 % kaempferol), flavanols (6 % catechin, 29 % epicatechin, and 10 % epi‑gallocatechin) and anthocyanins (21 % malvidin, 16 % cyaniding and 13 % peonidin, 22 % petunidin) than controls. Moreover, Ca and Zn foliar application was also effective in preserving the levels of trans-resveratrol and phenolic acids in grape berries. The higher amount of phenolic compounds in Ca + Zn-treated grapes was accompanied with higher activity of antioxidant enzymes, lower activity of polyphenol oxidase, and lower incidence of fungal decay. In general, post veraison spray of Ca and Zn is promising viticultural operation for preserving berries bioactive compound and mitigating chilling injury of grape during cold storage.

Bee pollen as a food and feed supplement and a therapeutic remedy: recent trends in nanotechnology.

Pollen grains are the male reproductive part of the flowering plants. It is collected by forager honey bees and mixed with their salivary secretions, enzymes, and nectar, which form fermented pollen or "bee bread" which is stored in cells of wax honeycombs. Bee pollen (BP) is a valuable apitherapeutic product and is considered a nutritional healthy food appreciated by natural medicine from ancient times. Recently, BP has been considered a beneficial food supplement and a value-added product that contains approximately 250 different bioactive components. It contains numerous beneficial elements such as Mg, Ca, Mn, K, and phenolic compounds. BP possesses strong antioxidant, anti-inflammatory, antimicrobial, antiviral, analgesic, immunostimulant, neuroprotective, anti-cancer, and hepatoprotective properties. It is used for different purposes for the welfare of mankind. Additionally, there is a growing interest in honey bee products harvesting and utilizing for many purposes as a natural remedy and nutritive function. In this review, the impacts of BP on different organisms in different ways by highlighting its apitherapeutic efficacy are described.

Unraveling the intrinsic mechanism behind the retention of arsenic in the co-gasification of coal and sewage sludge: Focus on the role of Ca and Fe compounds

Minimizing the emission of arsenic (As) is one of the urgent problems during co-gasification of Shenmu coal (SM) and sewage sludge (SS). The intrinsic mechanism of As retention was obtained by analyzing the effect of different SM addition ratios on the As form transformation during co-gasification at 1000 °C under CO2 atmosphere. The results showed that the addition of SM effectively promoted the enrichment of As in the co-gasified residues. Especially, the best As retention rate of 65.71% was achieved with the 70 wt% addition ratio of SM. The addition of SM promoted the adsorption and chemical oxidation of As(III) to the less toxic As(V) through the coupling of Ca and Fe compounds in the co-gasified residues. XRD and XPS results indicated that Fe2O3 adsorbed As2O3(g) after partial conversion to Fe3O4 by the Boudouard reaction, while part of As2O3 was oxidized to As2O5 by lattice oxygen. Finally, the generated As2O5 was successively trapped by CaO and Fe2O3 to form stable Ca3(AsO4)2 and FeAsO4. HRTEM and TEM analysis comprehensively proved that As(III) was stabilized by the lattice cage of CaAl2Si2O8. In conclusion, the co-oxidation of Ca and Fe compounds and lattice stabilization simultaneously played a crucial role in the retention of As2O3(g) during co-gasification.

Insight into the physical properties of lead-free Chloroperovskites GaXCl3 (X = Be, Ca) compounds: probed by DFT

Insight into the physical properties of lead-free Chloroperovskites GaXCl3 (X = Be, Ca) compounds: probed by DFT

Effect of different metal oxides on the Radiation shielding features of borate glasses

Three zinc barium-borate glasses were produced in the current work, incorporating different metal oxides (MO) (CaO, TiO2, and CuO) via the melt quenching technique under a 1100 °C melting temperature for 60 min. The fabricated samples' density is 4.112 g/cm3, 4.157 g/cm3, and 4.261 g/cm3 for glasses dopped with CaO, TiO2, and CuO, respectively. Additionally, the Makishima-Mackenzie model was employed to evaluate the effect of metal oxides on the fabricated glasses' mechanical properties. The study shows that the glasses with TiO2 have the highest mechanical moduli and microhardness which reach 4.67 GPa. The gamma-ray shielding properties in the 0.033–2.506 MeV energy interval were estimated by applying Monte Carlo simulation. The study demonstrates that the glass samples containing CuO exhibit the highest linear attenuation coefficient (LAC) when compared to the glasses containing Ca and TiO2 compounds. The LAC of the CuO-doped glasses varied between 28.367 cm−1 and 0.163 cm−1 when the photon energy was raised between 0.033 MeV and 2.506 MeV. Also, the study shows good shielding parameters (half-value layer, lead's equivalent thickness, and radiation protection efficiency) for the glasses doped CuO compared to glasses doped Ca and TiO2.

Influence of strontium and donor ion substitution on the dielectric, optical, and nonlinear characteristics of (Ca0.9Sr0.1)0.95A0.033Cu3Ti4O12 ceramics

This study expands on a previous investigation by substituting lanthanum with various trivalent ions in the compound (Ca0.9Sr0.1)0.95A0.033Cu3Ti4O12 (A = La3+, Sm3+, Sc3+, Gd3+, Y3+ and Bi3+) through solid-state synthesis. The analysis includes microstructures, optical, dielectric, and nonlinear properties. Sr2+/A3+-doped CCTO exhibits a significant reduction in grain size. The doped samples display a band gap ranging from 3.22 eV to 3.36 eV, with high dielectric permittivity (ε'≈4.51 × 103-5.37 × 104). Additionally, Sr2+/A3+ doping enhances the thermal stability compared to pure CCTO ceramic. Specifically, Sr2+/Sc3+-doped compound shows low loss tangent (tanδ≈0.04) at 60 °C, with the dielectric loss remaining below 0.1 over a temperature range from 50 °C to 160 °C. Furthermore, there is a significant improvement in breakdown voltage (Eb = 8420 V/cm), which is 23 times higher than CCTO (362.5 V/cm), and the coefficient α increases from 3.28 to 12.76. These enhancements are attributed to inhibiting the formation of Ti3+ and reducing oxygen vacancies.

Enhancement in thermoelectric performance of hydrothermally synthesized Ca and Sb co-doped Bi2Te3 nanostructures

−Ca & Sb co-doped Bi2Te3 compounds have been prepared by hydrothermal method at 210 °C for 24 h and investigated their thermoelectric properties. Phase purity and crystallinity were analyzed by XRD. All the prepared samples have rhombohedral crystal structure with space group R-3m. The hexagonal nanoplate-like morphology was examined by FESEM. Elemental analysis was done with EDX. Band gap energy of prepared samples has values in the range of ∼0.40–0.65 eV, obtained by Tauc plot. The Raman shift was obtained at a lower frequency with doping. Carrier concentration increased with doping from 3.18 × 1020 cm−1 to 9.34 × 1020 cm−1. The high value of power factor (PF) of ∼10.8 × 10–4 Wm−1K−2 was obtained due to high carrier concentration. An ultralow lattice thermal conductivity of ∼0.28 and ∼0.63 W mK−1 at 420 K, was obtained for Ca0.06Bi1.88Sb0.06Te3 and pure Bi2Te3, respectively. A maximum ZT of ∼0.78 at 386 K was obtained for Ca0.03Bi1.94Sb0.03Te3. The value of ZT thus obtained is about ∼ 51% higher than the ZT of pure Bi2Te3 (∼0.39 at 386 K).

Evaluation of the influence of surface and subsurface acidity correction methodologies on soil compaction in agropastoral systems under no‐till

AbstractSurface and subsurface acidity and soil compaction restrict root exploration and impair crop yields in agropastoral systems under no‐till. To support the development of surface and subsurface acidity correction methodologies that can decrease soil compaction in agropastoral systems under no‐till, this study tested the following hypotheses: (a) the incorporation of limestone with plowing and harrowing (conventional tillage) for surface and subsurface acidity correction decreases soil compaction in agropastoral systems under no‐till, (b) the subsurface application of hydrated lime with a shank subsoiler‐fertilizer (minimum tillage) for surface and subsurface acidity correction decreases soil compaction in agropastoral systems under no‐till, and (c) the surface application of Ca compounds (no tillage) for surface and subsurface acidity correction increases soil compaction in agropastoral systems under no‐till. In a field experiment in an agropastoral system under no‐till in an Arenic Hapludalf in Brazil, the abilities of three application management methodologies (no tillage, conventional tillage, and minimum tillage) for three Ca compounds (limestone, phosphogypsum, and hydrated lime) to ameliorate acidity in the surface and subsurface layers and decrease soil compaction were evaluated. The experimental design was a randomized complete block with four replications. The results support the following conclusions: (a) the incorporation of limestone with plowing and harrowing does not decrease soil compaction in agropastoral systems under no‐till; (b) the subsurface application of hydrated lime with a shank subsoiler‐fertilizer does not decrease soil compaction in agropastoral systems under no‐till; and (c) the surface application of limestone does not increase soil compaction in agropastoral systems under no‐till.

ИЗУЧЕНИЕ ВОЗМОЖНОСТИ ИСПОЛЬЗОВАНИЯ РАЗЛИЧНЫХ КАРБОНАТНЫХ ПОРОД ПРИ СИНТЕЗЕ КАЛЬЦИЕВО-АЛЮМОФЕРРИТОВОГО КЛИНКЕРА

The article considers the possibility of using carbonate rocks of limestone, marl and chalk in the synthesis of calcium-aluminoferrite clinker (CAFC). The analysis of the structure of carbonate rocks, as well as their influence on the physico-chemical processes occurring during the synthesis of calcium-aluminoferrite clinker, is given. Phase formation has been studied in the temperature ranges 900-1000 °C and 1100-1200 °C with an isothermal exposure of 20 minutes. The heat treatment mode has been selected to obtain the basic phase composition of calcium-aluminoferrite clinker. The dynamics of changes in the qualitative phase composition of firing products at various temperatures, ranging from 900 °C to the clinker sintering temperature of 1200 ° C, as well as quantitative characteristics of the intensity of formation of the main clinker phases are presented. It was found that during the firing of CAFC in the temperature range of 900-1000 °C, raw materials mixtures gradually undergo a number of physico–chemical transformations, the main of which are thermal dissociation of CaCO3, the formation of intermediate phases (CS, CF, Al2O3•4SiO2, Al2O3•SiO2), as a result of decomposition of accompanying minerals and solid-phase interactions, as well as the beginning of the formation of clinker compounds CA, C2AS and C2F. It is proposed to use for the limestone-bauxite composition a temperature of 1150 °C with an exposure of 40-60 minutes, marl-bauxite - 1100 °C with an exposure of 30-40 minutes and chalk-bauxite- 1100 °C with an exposure of 30-40 minutes.

Cinnamaldehyde Acts as a Fungistat by Disrupting the Integrity of Fusarium oxysporum Fox-1 Cell Membranes

To counter the harmful impacts of agricultural chemicals on the environment and human health, there is an increasing demand for safe, eco-friendly, and potent plant-based biopesticides. In this study, we aimed to investigate the antimicrobial effects of ginger essential oil and selected volatile compounds (linalool, eugenol, citral, and cinnamaldehyde [CA]) against Fusarium oxysporum FOX-1. Minimum inhibitory concentrations (MICs) were determined using the mycelium growth inhibition method. The compound CA exhibited the most potent antifungal effect against F. oxysporum FOX-1 and was selected for further investigation. After treatment with CA at 1/2 MIC or MIC, the spore germination of F. oxysporum FOX-1 was significantly inhibited at 12 h. Furthermore, microscopic observation revealed that CA treatment resulted in the morphological degradation of F. oxysporum FOX-1. CA destroyed the cell membrane integrity of F. oxysporum FOX-1, increasing the relative conductivity and the leakage of intracellular protein, nucleic acids, and malondialdehyde, affecting the integrity and metabolism of the cell membrane. The effects were positively related to CA concentration. Additionally, in vivo experiments with rhizome sections showed that CA significantly reduced the pathogenicity of F. oxysporum FOX-1. Overall, these findings provide evidence for the potential of using ginger essential oil components as fungicides, offering a basis for future research to develop robust and eco-friendly plant-derived fungicides that serve as a sustainable means to reduce fungus-driven agricultural losses.

Revealing the structural influence mechanism of intrinsic potassium/calcium elements on bio-waste-derived hard carbon for sodium-ion batteries.

Waste gourd shells enriched with ash-forming elements are selected as raw materials in this paper, discovering that the K and Ca compounds in the precursor not only exhibit the ability of self-forming pores, but also demonstrate catalytic graphitization of the hard carbon during the pyrolysis procedure.

Origin of positive/negative effects on pressure-dependent thermal conductivity: the role of bond strength and anharmonicity

The critical influence of atom size and chemical bonds on the thermal and thermoelectric properties of XSe (X = Be, Mg, Ca) compounds, considering pressure- and element-dependent anharmonicity in rocksalt and zinc blende configurations.

Integrated Project Based Learning (PjBL) with STEM and Field Study in Elemental Chemistry Learning

This research investigates the effectiveness of a project-based learning (PjBL) model integrated with Science, Technology, Engineering, and Mathematics (STEM) in enhancing students critical thinking and field study skills in Elemental Chemistry. The study aims to assess how this integrated approach influences student learning activities, including engagement with scientific literature, teamwork, cognitive skills enhancement, and the development of teaching materials for independent discovery. A mixed-methods approach was used, combining statistical analysis of quantitative data with qualitative insights from observation sheets, interviews, and student worksheets. The curriculum included soft skill training in sampling teak sawdust (Tectona grandis) and synthesizing oxalic acid, Ca, Ba, and Mg-oxalic compounds in the lab. Results showed significant improvement in student grades in the Elemental Chemistry course, with average scores in the good category ranging from 71.05% to 79.55%, indicating the PjBL model is effective. Furthermore, the development of an Elemental Chemistry learning kit specifically designed for the PjBL approach effectively enhanced student thinking skills, as evidenced by their achievements in STEM-related tasks, highlighting the potential of integrated learning method in improving educational outcomes in higher education chemistry courses.

Enhancement in the optoelectronic and thermoelectric properties of the NaASb (A= Ca, Sr and Ba) Sodium Antimonides via switching from P4/nmm to P62 m symmetry

Structural, opto-electronic and thermoelectric properties of square and butterfly like structured NaASb (A = Ca, Sr and Ba) Sodium Antimonides in tetragonal and hexagonal symmetries (P4/nmm and P62 m) are investigated using of density functional theory (DFT). Structural properties are in good agreement with the reported outcomes. Cohesive energy per atom (−8.233 to −26.1004 for P4/nmm and −8.522 to −28.7306 for P62 m symmetry) and enthalpy of formation per atom (−0.9468 to −2.6800 for P4/nmm and −1.1721 to −2.8034 for P62 m symmetry) for these compounds reveals that these compounds are stable in both P4/nmm and P62 m symmetries and are more stable in P62 m space group as compare to P4/nmm symmetry. Electronic properties show that the transition from indirect to direct band gap nature occurs by replacement of Ca/Sr by Ba in P4/nmm symmetry while P62 m symmetry all the NaASb (A = Ca, Sr and Ba) compounds are direct bandgap semiconductors. The band gap values lie in the range of 0–1.393 in P4/nmm symmetry and 0.542 to 1.547, respectively, in P62 m symmetry. Electrical conductivity also reveals the semiconducting characteristics of these compounds. The study shows that the replacement of Ca by Sr and Ba reduces the band gap and the reduction in bandgap values is greater in P4/nmm symmetry as compared to P62 m. The outcome demonstrates that these compounds NaASb (A = Ca, Sr and Ba) are implicitly active optically in the infrared region and are capable of serving as the primary applicant for optoelectronic devices. Thermoelectric properties like Seebeck coefficient (−138.5 to 154.7 μV/K in P4/nmm, −36.5 to −125.3 μV/K in P62 m at 500 K), Power factor (1.33–3.05 GW/mK2s in P4/nmm, 0.152–0.322 GW/mK2s in P62 m at 500 K) and thermoelectric figure of merit ranges from 0.495 to 0.946 in P4/nmm and 0.016 to 0.260 in P62 m at 500 K shows that these compounds are potential candidates for thermoelectric application in P4/nmm symmetry.

Lattice Thermal Conductivity in XMg2Sb2(X = Ca or Mg) Compounds: Temperature and High-Order Anharmonicity Effect

The binary compound Mg3Sb2 (also written as MgMg2Sb2) exhibits a much lower lattice thermal conductivity (κL) than its ternary analog CaMg2Sb2, despite its relatively low mass density and simple crystalline structure. Here, we perform a comparative first-principles study of the lattice dynamics in MgMg2Sb2 and CaMg2Sb2 based on the density functional theory, together with the self-consistent phonon theory and the Boltzmann transport theory. We show that the modest anharmonicity of CaMg2Sb2 renders the three-phonon processes dominant, and the temperature dependence of κL approximately follows the T−1 relationship. In contrast, the strong quartic anharmonicity of MgMg2Sb2 leads to the ultralow κL and weak temperature dependence, in agreement with the experimental observations. A comprehensive analysis reveals that the κLs in the two compounds are mainly carried by the acoustic phonons associated with the Sb atoms, and the different behaviors of κL result from the chemical bond changes around Sb atoms, which bond more covalently with the Mg atoms than the Ca atoms and thus lead to high-order anharmonicity in MgMg2Sb2. These results give us insights into the understanding of the anomalous thermal transport in thermoelectric materials.