calcium carbonate (Cimascal / Cimascal D Forte)

Spatiotemporal patterns and environmental controls of dissolved carbon and water-air CO₂ fluxes in Southwest China's alpine canyon rivers.

Wu Zihan Z, Wang Hongwei H, Li Yong Y, Yang Xiaobo X

Mountain rivers remain insufficiently understood within regional and global carbon cycles, particularly high-slope systems that are highly sensitive to anthropogenic disturbance and climate change. We investigated a high-slope alpine gorge river in southwestern China (Upper Min River) through five seasonal surveys in 2023, quantifying dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and water-air CO2 flux (FCO₂) and assessing their controls. DIC (8.28-58.97 mg/L; mean 32.61 mg/L) decreased from carbonate headwaters to downstream non-carbonate reaches, indicating strong carbonate-weathering control and providing the main inorganic substrate sustaining CO2 supersaturation. DOC (0.01-8.21 mg/L; mean 1.53 mg/L) was enriched near urban and agricultural sections, and its wet-season association with ammonia nitrogen suggests that storm runoff mobilizes anthropogenic organic matter. Yet DOC showed little relationship with FCO2, implying that rapid downstream export in steep channels limits in-stream DOC mineralization. FCO2 ranged from -1.90 to 227.78 mmol/(m²·d) (mean 24.05 mmol/(m²·d)) and was positive in >95 % of measurements, evidencing persistent CO2 evasion driven by inorganic carbon supply, turbulence, and reduced atmospheric pressure at high elevation. Carbonate-underlain turbulent reaches acted as outgassing hotspots, whereas retentive reaches exhibited reduced efflux or short-lived CO2 uptake during periods of high primary productivity. Overall, carbonate weathering, anthropogenic DOC inputs, and hydrodynamic conditions jointly regulate dissolved carbon and CO2 outgassing in alpine gorge rivers, underscoring their role in regional carbon budget assessments.

From organic waste compost to stable foams: pH-shifting and calcium ion synergy modulating protein interfacial behavior.

Sheng Qian Q, Fan Jinhong J, Dong Bin B, Xu Zuxin Z

Protein-based foaming agents exhibit potential for exceptional foaming capacity with broad industrial applicability, yet their high production costs drive the need for cost-effective and sustainable alternatives. This study unveils a novel synergistic strategy combining pH-shifting and calcium ion addition to transform organic waste compost protein (CP) into a high-performance foaming agent. Our approach utilizes pH-driven conformational adjustments to expose latent binding sites for calcium, enabling targeted interfacial reinforcement. The foaming capacity (FC) of the resulting CP was exceptional (>480 %). While untreated CP exhibited limited foam stability (FS, 58.86 %), 0.1 mol/L Ca2+ alone boosted FS to 81.31 %, and pH-shifting alone achieved 70.21 %. The dual treatment synergized these effects, reaching 85.02 % FS while fully retaining FC. Advanced characterization revealed two mechanisms: (1) calcium-specific interfacial pattern, evidenced by SEM-EDS showing calcium enrichment at bubble surfaces (21.67 % vs. 5.39 % in controls), and (2) protein restructuring, where Ca2+ coordinated with carboxyl/amino groups to compact CP's secondary structure with an increase of α-helix content from 5.46 % to 6.96 % and (α-helix/(β-sheet+random coil) ratio increased by 32 %. Crucially, pH-shifting further amplified protein adsorption at air-water interfaces by 113 % (from 12.2 % to 26.06 %), creating viscoelastic films resistant to coalescence. The synergy between molecular-level structural changes and interfacial calcium-protein complexes accounts for the markedly enhanced FS. This study provides a theoretical foundation and a technical pathway for producing cost-effective, eco-friendly foaming agents derived from organic waste compost protein, thereby facilitating its high-value valorization.

pH- and calcium-dependent solution-phase free fluoride in dental desensitizing gels: a preliminary in vitro study.

Piszko Paweł J PJ, Kulus Michał J MJ, Piszko Aleksandra A, Kiryk Jan J et al.

Dental hypersensitivity (DH) is a common clinical condition characterized by brief, intense pain. This condition is treated with fluoride-containing specialized dental gels. The effect of calcium ions present in saliva and pH of the oral cavity are indicated as factors affecting their clinical performance. In the presented study, two dental desensitizing gels were evaluated. Fourier Transform Infrared Spectroscopy (FTIR) spectra of the gels were registered and analyzed. Measurement of concentration of measurable free fluoride ions and pH in vitro assessment was performed using selective electrodes. Measurement with addition of TISAB witch CDTA was performed to evaluate the amount of fluoride bound within the gel matrix. Univariate and multifactorial ANOVA tests were used to analyze acquired results of measurable free fluoride in twelve distinct incubation solutions. The highest values of free, measurable fluoride were obtained after addition of TISAB with CDTA. However, in physiological study without ionic strength adjuster and chelator, the highest free, measurable fluoride observed in the artificial saliva solutions was 1,043 ppm for the SensiKIN desensitizing gel at pH 4.5 in the solution without calcium ion addition. The lowest value (658 ppm) was denoted for the Teeth Desensitiser TD gel at pH 7.0 with calcium ion addition. The presented amounts of fluoride pertain to measurable free fluoride in solution. It has been shown that the presence of calcium in saliva reduces the concentration of measurable free fluoride in solution (by as much as 137 ppm). Although the effect of presence of Ca2+ is pronounced, the initial pH remains the most significant variable. Observed levels of measurable free fluoride in solution might reflect initial and preliminary bioavailability under static in vitro conditions. Measurable free fluoride may serve as an indirect analytical proxy for potentially available fluoride under the tested in vitro conditions. However, it does not represent direct biological or clinical bioavailability. The evaluated desensitizing gels showed maximal free, measurable fluoride concentration under acidic conditions. For studies incorporating TISAB/CDTA, the most profound effect on F- concentration was gel composition. Future formulation studies could investigate whether calcium- complexing or buffering components influence measurable solution-phase free fluoride under standardized in vitro conditions.

Intravascular lithotripsy in chronic total occlusion PCI: expanding the calcium modification armamentarium with cautious optimism.

Vijayvergiya Rajesh R, Mukherjee Anirudh A