Addition Of Calcium Research Articles

Impact of Phytase Treatment and Calcium Addition on Gelation of a Protein-Enriched Rapeseed Fraction

Rapeseed press cake was upcycled as a protein-enriched ingredient through dry fractionation. The protein-enriched fraction contained higher amounts of phytic acid compared to press cake, and phytase treatment was applied to decrease the phytic acid content from 6.8 to 0.5%. The effect of phytase treatment leading to the release of cations was also mimicked by extrinsic calcium addition. Both phytase treatment and calcium addition significantly improved the heat-induced gel properties but had a minor effect on protein solubility and dispersion stability at pH 8. Water and protein holding capacities of the gels were the highest for the phytase-treated sample (91 and 97%, respectively), followed by the sample with added calcium (86 and 94%, respectively) and control sample (60 and 86%, respectively). Gel firmness followed the same pattern. Scanning electron microscopy images revealed an interconnected structured network in the phytase-treated gel, while in the control gel, a more rigid and open structure was observed. The improved gelation properties resulting from the phytase treatment suggest that the protein and soluble dietary fibre-enriched rapeseed press cake ingredient serve as a promising raw material for gelled food systems. The positive effect of calcium addition on gel properties proposes that part of the improvement observed after phytase treatment may be caused by cations released from phytate.

Enhancement of separation rate and recovery efficiency of milk whey proteins by addition of calcium and magnesium ions in batch foam separation

The influence of Ca2+ and Mg2+ to milk whey solution at pH 6 on the enhancement of proteins recovery in batch foam separation was investigated. The pH of whey solution produced in cheese production was about pH 6. The separation rate was evaluated by the separation rate constant, k, by fitting to first-order kinetic equation, and the recovery efficiency was evaluated by the fraction of residual concentration of whey proteins. In the comparison of the case without and with the addition at pH 6, in the case with the addition of Ca2+ and Mg2+ in the range over 0.06 mol/L, the k became 4.4-fold and 2.0-fold larger, and the recovery efficiency became 5.3-fold and 1.9-fold larger than those in the case without the addition. The overall equilibrium adsorption constant, K, and the overall saturated adsorption density, Xs, were also affected by the addition of Ca2+ and Mg2+. The variation tendency of K and Xs was quite different. As increasing the concentration of both Ca2+ and Mg2+, mostly K decreased, on the other hand, Xs increased. Judging from these results, the formation of aggregates/complexes of whey proteins by the addition of Ca2+ and Mg2+ was suggested. The addition of Ca2+ and Mg2+ could enhance the separation rate and recovery efficiency.

Catalytic Features and Thermal Adaptation Mechanisms of a Deep Sea Bacterial Cutinase-Type Poly(Ethylene Terephthalate) Hydrolase.

Poly (ethylene terephthalate) (PET) plastic is chemically inert and persistent. Massive quantities of PET waste end up in landfill sites and oceans, posing major global pollution concerns. PET degrading enzymes with high efficiency provide plastic recycling and bioremediation possibilities. Here, we report a novel cutinase, MtCut with distinct catalytic behaviors, derived from the deep sea Nocardiopsaceae family strain. Biochemical analyses showed MtCut efficiently hydrolyzed PET at ambient temperatures and in an exo-type manner. The activity and stability of MtCut were enhanced by the addition of calcium ions. Notably, no hydrolysis products inhibition was observed during PET depolymerization, suggesting MtCut is a better biocatalyst when compared to other PET hydrolases. In addition, structural components associated with thermal adaptation were investigated using molecular dynamic (MD) simulations, and key regions regulating MtCut thermostability were identified. Our biochemical and structural analyses of MtCut deepen the understanding of PET hydrolysis by cutinases, and provide invaluable insights on improvement and performance engineering strategies for PET-degrading biocatalysts.

Relationship between the coprecipitation of phosphorus-on-calcite by submerged macrophytes and the phosphorus cycle in water

To assess potential phosphorus removal, we utilized Potamogeton crispus to determine the effects of calcium addition on phosphorus removal. Plastic film was used to block material exchange between the overlying water and the sediment, and we compared the experimental results with long-term monitoring results of Yimeng Lake, which contained a dense population of P. crispus. The results revealed that the first 10–40 days constituted a period of rapid P decrease, as P. crispus could effectively remove the phosphorus in the water through coprecipitation of CaCO3–P. The treatment groups indicated that P. crispus released calcium into the overlying water, and after the addition of calcium ions, P. crispus showed increased phosphorus removal efficiency in the water. Total phosphorus (TP) and P/Ca content increased with increasing pH in the treatment groups, and the TP and pH declined as the calcium content increased in the treatment groups. Long-term field observations showed that the calcium-to-phosphorus ratio in the coprecipitates was dependent on the pH during the crystallization process. Thus, water calcium driven by P. crispus plays an important role in the phosphorus cycle of water, due to P. crispus assisted precipitation. This study revealed the effect of P. crispus on the water purification, the migration and transformation of Ca and P in sediment and overlying water under the condition of sediment calcium addition, so as to provide a theoretical basis for the ecological restoration of shallow lakes eutrophication.

Characterization of Calcium Oxide Treated Lead–Lead Dioxide Vitroceramics from Recycled Automobile Batteries by X-Ray Diffraction, Infrared and Ultraviolet–Visible Spectroscopy, and Voltammetry

Today the number of automobiles is increasing, and hence, the demand for lead-acid batteries is enhanced. Improvements regarding reusable car batteries implies the elimination of disadvantages of the traditional recycling methods. The purpose of this work is: (i) to recycle the spent plates from a car battery with high wear by an eco-innovative method and (ii) to characterize the prepared materials and to characterize their electrochemical performance for new electrodes for batteries. The prepared samples were investigated by X-ray diffraction, infrared and ultraviolet–visible spectroscopy, and cyclic voltammetry and linear sweep voltammetry. The results show that following the addition of calcium ions into the lead–lead dioxide recycled matrix and the formation of Ca3(SO3)2SO4 crystalline phase were evident. These results suggest that no emissions of sulfur oxides into the atmosphere.

Compositional changes of casein micelles induced by calcium or chelatant addition at threefold and natural casein concentration

Milk protein concentrates are gaining importance in dairy products design and manufacture. The effect of adding CaCl2 or trisodium citrate (TSC) at various concentrations to micellar casein concentrate (MCC) with threefold concentrated casein micelles (CM) was assessed and compared with natural casein concentration. CM in MCC and in a skim milk-like system (MLC) were analysed regarding soluble and sedimentable casein, micellar calcium, phosphate, and micelle hydration. We hypothesised that casein micelles in MCC are less affected by these milieu changes. In fact, concentrated CM showed less pronounced compositional changes induced by TSC and CaCl2 addition. CM in MCC were less saturated in calcium and phosphate at higher levels of CaCl2 addition than in MLC. 94.2% of the CM remained intact up to 15 mm TSC addition, but only 41.5% CM in MLC. This study yields a wider understanding of CM if applied in concentrated form and provides options for modifying their functionalities.

Bioremediation of stainless steel pickling sludge through microbially induced carbonate precipitation

In this study, microbial induce carbonate precipitation (MICP) was introduced to immobilize chromium (Cr) in stainless steel pickling sludge (SSPS). Two methods were utilized to conduct the MICP process — Bacteria lysis liquor (BLL)-based MICP and bacteria-based MICP. BLL was obtained by breaking the cell walls with ultrasonic treatment. The urea hydrolyzation test illustrated that the BLL was better than bacteria solution. Both the treatments of bacteria lysis liquor-based MICP and bacteria-based MICP process can effectively entrap the Cr into mineral lattices, that reduce the potential environmental risk of SSPS. With 30 g/L urea and 7 days’ treatment, BLL-based MICP presented better immobilization performance than bacteria-based MICP by lowering the bacteria concentration (OD600) from 0.8 to 0.7. The excellent biosorption of BLL contributed to Cr removal. Nevertheless, the addition of calcium (Ca) significantly enhanced the immobilization performance of bacteria-based MICP process rather than BLL-based MICP process. pH-dependent leaching tests illustrated the leaching of Cr followed an amphoteric pattern, while the leaching of Ni and Ca followed the cation pattern. Geochemical modeling revealed that the leaching of Cr from bio-mineralized products was solubility-controlled by Cr(OH)3 and Cr2O3.

Enhanced Removal of Malachite Green Using Calcium-Functionalized Magnetic Biochar.

To efficiently remove malachite green (MG), a novel calcium-functionalized magnetic biochar (Ca/MBC) was fabricated via a two-step pyrolysis method. Iron-containing oxides endowed the target complexes with magnetic properties, especially the chemotactic binding ability with MG, and the addition of calcium significantly changed the morphology of the material and improved its adsorption performance, especially the chemotactic binding ability with MG, which could be confirmed through FTIR, XPS, and adsorption experiments. Electrostatic adsorption, ligand exchange, and hydrogen bonding acted as essential drivers for an enhanced adsorption process, and the maximum theoretical adsorption capacity was up to 12,187.57 mg/g. Ca/MBC maintained a higher adsorption capacity at pH = 4–12, and after five adsorption–desorption cycles, the adsorption capacity and adsorption rate of MG remained at 1424.2 mg/g and 71.21%, highlighting the advantages of Ca/MBC on adsorbing MG. This study suggests that biochar can be modified by a green synthesis approach to produce calcium-functionalized magnetic biochar with excellent MG removal capacity. The synthetic material can not only remove pollutants from water but also provide an efficient way for soil remediation.

Long term variation of leaf abundance in a northern hardwood forest

Leaf abundance of trees plays a dominant role in energy, water and nutrient flux of forest ecosystems, in defining the habitat structure of entrained biota and in mediating interspecific competition among tree species. We quantified leaf abundance of three dominant tree species (Acer saccharum Marsh.; Fagus grandifolia Ehrh.; Betula alleghaniensis Britt.) for 27 years in mature northern hardwood forest at the Hubbard Brook Experimental Forest, New Hampshire, USA using annual counts of leaves of each species collected in 117 litter traps (0.1 m2, each). We hypothesized that variation in leaf abundance would reflect known disturbance events and canopy dieback episodes. No significant trend in leaf abundance of the three species over 27 years (1993–2019) was observed in seven reference stands despite known canopy dieback of sugar maple and American beech in these stands, indicating that 1) maple decline preceded our sampling interval and 2) expansion of beech understory compensated for canopy dieback caused by beech bark disease. Leaf abundance temporarily declined significantly in response to known disturbances (ice storm, 34 to 47%; late-spring frost, 13 to 16%). Increased leaf abundance, especially for sugar maple (30%), on a watershed where calcium addition restored acidified soils, was probably associated with increased soil pH, Ca availability and decreased Al. The temporal sequence of decline of paper birch at higher elevations following a severe drought in 2002 also was apparent. Leaf abundance based on leaf litterfall in deciduous forests provides a useful indicator of forest ecosystem function and forest health.

Corrosion behavior of AZ31 magnesium alloy with calcium addition

The effect of calcium on microstructure and corrosion characteristics of AZ31 was investigated. Electron probe microanalysis, scanning electron microscopy and electron back-scattered diffraction were employed for microstructural analysis. Corrosion behavior was characterized by open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy in NaCl at different pH levels. Microstructural observations confirmed the formation of (Mg,Al)2Ca in AZ31–0.5Ca. The corrosion rates were 84.21 mpy/ 31.71 mpy and 23.42 mpy/ 9.40 mpy for AZ31 and AZ31–0.5Ca at pH 6 and pH 11, respectively. Improved corrosion resistance was attributed to segregation of aluminum with calcium to form (Mg,Al)2Ca which reduced β-Mg17-Al12 area fraction.

Phosphorus recovery from pig manure: Dissolution of struvite and formation of calcium phosphate granules during anaerobic digestion with calcium addition

Phosphorus is an essential but finite and scarce element, which is used extensively in pig farming. For recovering phosphorus from pig manure, we hypothesize that calcium addition during anaerobic treatment can trigger calcium phosphate granulation and enable efficient phosphorus recovery. In this study, we tested the recovery of phosphorus from pig manure by adding calcium during anaerobic treatment. Size–separated (<200 µm) pig manure was treated in two identical up-flow anaerobic sludge blanket reactors for 456 days. Calcium was supplied to one of the reactors to study calcium phosphate granulation.Calcium addition showed a positive effect on treatment stability and efficiency, increasing chemical oxygen demand and phosphorus removal. Phosphorus removal increased from 60% without calcium addition to 74% with calcium addition. The addition of calcium increased the phosphorus concentration in significantly larger particles, calcium phosphate granules, (79% >0.4 mm compared with 11% without calcium addition) in the reactor with calcium addition, which enables separation and a transport reduction of 85% for the recovered phosphorus. The main phosphorus phase in the reactor sludge bed changed from struvite to calcium phosphate with calcium addition. The Mg:P molar ratio was 0.09 with calcium addition and 0.88 without calcium addition in particles >2.5 mm. Thus, calcium addition enhances the treatment of pig manure and enables phosphate recovery as calcium phosphate granules.

The effects of calcium hydroxide and activator chemistry on alkali-activated metakaolin pastes exposed to high temperatures

Having a detailed understanding of the high temperature behavior of alkali-activated metakaolin (AAMK) is important for use of this material in fire resistance applications. Here, we assess the impact of a small amount of calcium hydroxide (10 wt% replacement for metakaolin) on the phase formation, pore structure and microstructure of AAMK exposed to temperatures of up to 900 °C. 5 and 10 M NaOH-activated pastes, and equivalent molarity Na2SiO3-activated pastes, with and without calcium hydroxide are characterized using Fourier transform infrared spectroscopy and X-ray diffraction to identify the crystalline phases that form on heating and the likely location of calcium within the material. Mercury intrusion porosimetry and scanning electron microscopy provide a detailed understanding of the evolution of the pore network on heating and degree of densification of the samples. It is found that the calcium addition enhances the formation of nepheline on heating and reduces the concentration-dependent differences seen between the 5 and 10 M Na2SiO3-activated systems.

Anodized titanium with calcium and phosphorus surface enhancements for dental and orthopedic implant applications

Titanium anodization in mixed-acid electrolytes containing phosphoric acid has been shown to result in phosphorus (P)-doped amorphous or crystalline titanium oxide layers. Recently, aqueous hydrothermal soak treatments have been shown to further enhance the bioactivity of titanium and titanium oxide through the addition of calcium (Ca) to the specimen surfaces. For the present study, a combination of mixed-acid electrolyte anodization and subsequent calcium nitrate tetrahydrate (Ca(NO3)2) hydrothermal treatments were used to create optimized titanium specimens with favorable Ca/P surface ratios. Commercially pure titanium specimens were anodized in two mixed-acid electrolytes to final forming voltages of 72 V, 108 V, or 180 V. Three specimens per group were subsequently soaked for 72 h at 80°C in 1.2 M Ca(NO3)2 solution. Energy dispersive spectroscopy revealed the Ca(NO3)2-soaked specimens anodized to 108 V in each electrolyte exhibited favorable surface Ca/P ratios averaging of 2.27 and 1.67. Bioactivity testing revealed increased apatite formation on 108 V Ca(NO3)2-soaked specimens compared to their un-soaked counterparts. Pre-osteoblast cell culture studies showed similar cellular proliferation and differentiation but increased mineralization on Ca(NO3)2-soaked specimens. This two-step combination of anodization and subsequent Ca(NO3)2 hydrothermal treatments shows great promise for future biomaterials applications.

A new high strength Al–Mg–Sc alloy for laser powder bed fusion with calcium addition to effectively prevent magnesium evaporation

A precise control of the Mg content in Al–Mg alloys is essential to obtain predictable mechanical properties but the processing of Al–Mg alloys often suffers Mg losses due to Mg evaporation and oxidation. A new high strength Al–Mg–Sc alloy designed for LPBF (laser powder bed fusion) processing has been developed here, where Mg losses are effectively prevented by the addition of a low amount of calcium. A LPBF processing window which results in built parts with a 99.7% relative density and no detectable loss of Mg has been identified. The as-built microstructure of the new Calciscal® alloy, studied by transmission electron microscopy, is found to comprise areas of fine equiaxed grains and areas of coarser grains, with many Al 4 Ca precipitates present at the grain boundaries and within the coarser grains. After a subsequent ageing of 1 h at 375 °C, the tensile strength of Calciscal® is increased by 44% compared to the as-built condition and reaches 522 ± 2 MPa. The increase in strength observed in the heat-treated condition comes from the additional precipitation of numerous finely dispersed Sc-rich precipitates. This high strength, combined with a good ductility, makes Calciscal® competitive to other Al alloys and suitable for structural applications. Moreover, Calciscal® shows very reproducible tensile properties thanks to the Ca addition which leads to a better control and less variations of the Mg content in the alloy.

Effect of ion-exchangeable calcium on carbonaceous particulate matter formation during coal pyrolysis

This work investigated the effect of ion-exchangeable calcium on the mass yield, size distribution and structural properties of carbonaceous particulate matter from coal pyrolysis. The raw, acid washed and calcium-exchanged coal samples were pyrolyzed in a flat-flame burner at 1600 K. The particulate matter was collected with a three-stage dilution sampler. Then, the particle size distributions were measured by a low pressure impactor (DLPI+) and a scan mobility particle sizer (SMPS). The results show that, with the addition of ion-exchangeable calcium, the soot yield reduces, and the size growth of soot particles is inhibited. Transmission electron microscopy (TEM) analysis shows that ion-exchangeable calcium diminishes the sizes of disordered cores in soot primary particles, accelerates the graphitization of soot and makes the soot aggregates more compact. The chemical structures derived from Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) indicate that the graphitization degree of the soot is first enhanced and then inhibited with increasing calcium loading amount. Additionally, the inorganic species in the size-segregated soot particles were characterized. The fractions of calcium and sodium in soot show opposite trend with particle size. Unlike Na, which nucleates before soot inception, Ca tends to participate in both the soot nucleation and surface growth processes, and is enriched at larger particle size.

Structural and rheological properties of mung bean protein emulsion as a liquid egg substitute: The effect of pH shifting and calcium

The objective of this study was to develop functional egg substitutes using mung bean protein (MBP) through pH12-shifting modification and calcium addition. The influence of pH12-shifting and Ca2+ ions on emulsion stability and the physical properties of MBP-based emulsion gels were elucidated in a neutral (pH 7) composite system (7.2% MBP and 10% canola oil). Results showed that the pH12-treated MBP emulsions were stable even after 5-day storage at 25 °C. The pH12-shifting significantly decreased the average emulsion droplet size from 524 nm in emulsion of native MBP to 422 nm. The emulsion samples were further heated at 95 °C to induce the formation of gels. With the calcium addition of 0 or 5 mM, the pH12 MBP emulsion did not form self-supporting gels. In the presence of 10–20 mM Ca2+, emulsion gels prepared with pH12-treated MBP exhibited a uniform and compact network structure. The gel hardness, water-holding capacity, and water distribution of pH12-treated MBP emulsion gels were superior to that of the native MBP samples. This study demonstrated MBP-based emulsion gels can be improved by pH12-shifting treatment in combination with calcium addition, resulting in a similar texture to egg, hence, the potential to develop MBP-based egg substitutes.

Evaluation of the influence of chromium and zinc ions on the collagenolysis process in solutions by the method of dynamic light scattering

Using the method of dynamic light scattering, it was found that the rate of collagen cleavage under the influence of bacterial collagenase decreases by almost 4 times when protein molecules are doped with Cr3+ ions, and when the enzyme activator of Zn2+ ions is added, it increases by 1.3 times. Based on the experimental data, the reaction rate constants k1 were calculated. It was found that when collagen molecules are tanned with a chromium salt, it becomes more resistant to degradation in solutions containing zinc ions than in solutions with the addition of calcium ions, as we described in earlier works. Keywords: collagen type 1, bacterial collagenase, chromium chloride, zinc chloride, dynamic light scattering method, translational diffusion coefficient, hydrodynamic radius, reaction rate constant, collagenolysis, Clostridium histolyticum.

Оценка влияния ионов хрома и цинка на процесс коллагенолиза в растворах методом динамического рассеяния света

Using the method of dynamic light scattering, it was found that the rate of collagen cleavage under the influence of bacterial collagenase decreases by almost 4 times when protein molecules are doped with Cr3+ ions, and when the enzyme activator of Zn2+ ions is added, it increases by 1.3 times. Based on the experimental data, the reaction rate constants k1 were calculated. It was found that when collagen molecules are tanned with a chromium salt, it becomes more resistant to degradation in solutions containing zinc ions than in solutions with the addition of calcium ions, as we described in earlier works.

Characterization of Sodium and Calcium Addition on Immediate Aqueous Interactions of Binary Borate Glasses by Dynamic Vapour Sorption with In-Situ Raman

Characterization of Sodium and Calcium Addition on Immediate Aqueous Interactions of Binary Borate Glasses by Dynamic Vapour Sorption with In-Situ Raman

Tailoring the phosphorus release from biochar-based fertilizers: role of magnesium or calcium addition during co-pyrolysis.

The presence of magnesium (Mg) and calcium (Ca) in biochar-based fertilizers is linked to the slow release of phosphorus (P), but these alkali metals have not been systematically compared under identical conditions. In this study, sugarcane filter cake was treated with H3PO4 and MgO or CaO followed by pyrolysis at 600 °C to produce a Mg/P-rich biochar (MgPA-BC) and a Ca/P-rich biochar (CaPA-BC), respectively. The P-loaded biochars were studied by extraction and kinetic release in water over 240 hours to assess the potential P availability. X-ray diffraction and Fourier-transform infrared (FTIR) spectroscopy were used to characterize the pristine and post-kinetics biochars to identify the responsible phases for phosphate release. Additionally, the dissolved P concentrations in the kinetic release experiment were compared to thermodynamic solubility calculations of common Mg and Ca phosphates. Both MgPA-BC and CaPA-BC had P loadings of 73-74 g kg-1 but showed distinctly different release behaviors. Phosphate dissolution from MgPA-BC was gradual and reached 10 g P per kg biochar after 240 hours, with rate-determining phases being Mg2P2O7 (Mg pyrophosphate), MgNH4PO4·6H2O (struvite), and Mg3(PO4)2·22H2O (cattiite). In contrast, CaPA-BC only released 1.2 g P per kg biochar. Phosphate release from CaPA-BC was limited by the low solubility of Ca2P2O7 (Ca pyrophosphate) and (Ca,Mg)3(PO4)2 (whitlockite). Co-pyrolysis with MgO retained P in a more soluble and available form than CaO, making MgO a preferential additive over CaO to immobilize phytoavailable P in biochar-based fertilizers with higher fertilizer effectiveness.