Chelation Of Calcium Ions Research Articles

Impact of Protein Content on the Antioxidants, Anti-Inflammatory Properties and Glycemic Index of Wheat and Wheat Bran.

Conventional wheat milling generates important volumes of wheat bran (WB), which is a concentrated source of polyphenols and insoluble fiber. In terms of health benefits and based on epidemiological and experimental evidence, these compounds contribute to reducing the risk of certain chronic pathologies. Protein concentration is the main quality factor conditioning wheat use in the agroindustry. When turning waste into feasible resources, it is essential to evaluate the variability of the raw material. The aim of this study was the evaluation of the impact of protein content in the valorization of WB based on its antioxidants, anti-inflammatory properties and glycemic index (GI). A significantly (p ≤ 0.05) lower content of phenolic compounds was found in the whole grain (WG) fractions, both free (FP) and bound (BP), as compared to the WB phenolic fractions, differences that ranged from 4- to 6-fold (538 to 561 mg GAE 100 g−1 in WG vs. 1027 to 1236 in WB mg GAE 100 g−1 in FP and 2245 to 2378 vs. 6344 to 7232 mg GAE 100 g−1 in BP). A significant (p ≤ 0.05) effect of the protein content on the resulting phenolic content and antioxidant capacity was observed, especially in WG, but also in WB, although in the latter a significant (p ≤ 0.05) negative correlation was observed, and increasing the protein content resulted in decreasing total phenolic content, antioxidants, and ferric-reducing capacities, probably due to their different types of proteins. The highest protein content in WB produced a significant (p ≤ 0.05) reduction in GI value, probably due to the role of protein structure in protecting starch from gelatinization, along with phytic acid, which may bind to proteins closely associated to starch and chelate calcium ions, required for α-amylase activity. A significant (p ≤ 0.05) effect of the protein content on the GI was also found, which may be explained by the structural effect of the proteins associated with starch, reducing the GI (21.64). The results obtained show the importance of segregation of WB in valorization strategies in order to increase the efficiency of the processes.

Calcium-chelated nanosystem reversing cancer chemoresistance via replenishing intracellular calcium ions

Chemoresistance is the major reason for the failure of chemotherapy, which is a major cause of death in patients with advanced cancer. However, the current approach to reversing cancer chemoresistance is limited. Calcium ions are indispensable for all physiological activities of the body. Because a calcium concentration was reduced in chemoresistant cancer cells, we fabricated calcium-chelated nanoparticles upon self-assembly to replenish intracellular calcium ions in the cells. Through employing an amphipathic polyethylene glycosylated (PEGylated) lipids covalent bonding chelator molecule to bind calcium ions, the chelate calcium ions are used for the first time to reverse the chemoresistance of cancer cells. This nanoparticle released calcium ions more rapidly in a weakly acidic environment than in neutral and weak base conditions, which ensures the effective release of calcium ions in the acidic microenvironment of tumors. As assessed by in vitro and in vivo experiments, this calcium-chelated nanoparticle indeed restored calcium homeostasis and reversed chemoresistance in a variety of chemoresistant cancer cells, whereas calcium chloride solution did not increase the concentration of calcium ions in chemoresistant cancer cells. Furthermore, the mechanism study showed that calcium-chelated nanoparticles affected the expression of chemoresistant genes and promoted cancer cell apoptosis by inhibiting the NF-κB signaling pathway. In conclusion, our data provide direct insight into an effective approach for the reversal of chemoresistance and calcium-chelated nanoparticles may have potential applications for treating chemoresistant patients.

Sustainable Synthesis of Carbon Quantum Dots with Tailored Surface Functional Groups from Pomelo Peel Waste for Inhibiting Scale

AbstractFruit Shatian pomelo peel is a common solid biological waste. This article reports the environmentally friendly synthesis of carbon quantum dots from Shatian pomelo peel waste by hydrothermal method. The synthesized carbon quantum dots (named PCA‐CQDs) were characterized by transmission electron microscope (TEM), Fourier transform infrared (FT‐IR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), ultraviolet‐visible spectroscopy (UV‐vis) and excitation‐dependent fluorescence emission spectroscopy. The resultant carbon quantum dots were spherical, and the average particle diameter was measured to be 5 nm. The surface of PCA‐CQDs has been successfully modified with functional oxygen‐containing functional groups such as hydroxyl and carboxyl groups. Therefore, PCA‐CQDs exhibit excellent water solubility and calcium ion chelating properties. Most importantly, PCA‐CQDs were used as a new type of green scale inhibitor for inhibiting the CaSO4 and CaCO3 scale for the first time, and the scale inhibition efficiency can reach more than 95 %. By observing the changes of the scale crystals in the SEM image, it is speculated that the mechanism of PCA‐CQDs inhibiting calcium scale may include chelation, dispersion and lattice distortion.

Bioinspired Hydrogel Anchoring 3DP GelMA/HAp Scaffolds Accelerates Bone Reconstruction

Seeking high biological activity and osteoinductive ability has always been an urgent problem for three-dimensional-printed (3DP) bony implants. Here, a 3DP methacrylic anhydride-modified gelatin (GelMA)/hydroxyapatite (HAp) scaffold with a high solid content of 82.5% was prepared and anchored by a functionalized polyphenol hydrogel. The scaffold and hydrogel were organically integrated into a bioinspired bony implant (HGH) by phenolic hydroxyl of hyaluronan derivatives conjugating amino groups of collagen I and GelMA and further chelating calcium ions of HAp. Compared with a simplex 3DP scaffold, this freeze-dried HGH presented better water retention, delayed degradation, and mechanical stability. It could promote migration, proliferation, and osteogenic differentiation of bone marrow stem cells in vitro. One week of implantation showed that it promoted directional migration of endogenous stem cells and early osteogenesis and angiogenesis. After 15 week surgery of rabbit skull defects, the BV/TV value of HGH returned to 73% of the normal group level. This strategy provided a new research idea for bone regeneration.

Bioinspired cellulose‐integrated MXene‐based hydrogels for multifunctional sensing and electromagnetic interference shielding

AbstractBioinspired hydrogels are complex materials with distinctive properties comparable to biological tissues. Their exceptional sensitivity to various external stimuli leads to substantial application potential in wearable smart devices. However, these multifaceted hydrogels are often challenging to be combined with pattern customization, stimulus responsiveness, self‐healing, and biocompatibility. Herein, inspired by mussel secretions, a printable, self‐healing, and biocompatible MXene‐based composite hydrogel was designed and prepared by incorporating Ti3C2Tx MXene nanosheets into the hydrogel framework through the chelation of calcium ions (Ca2+) with polyacrylic acid and cellulose nanofibers at alkaline conditions. The biocompatible conductive hydrogel exhibited sensitivity (gauge factor of 2.16), self‐healing (within 1 s), recognition, and adhesion, distinguishing it as an ideal candidate for wearable multifunctional sensors toward strain sensing, vocal sensing, signature detection, and Morse code transmission. Additionally, the multifunctional hydrogel manifested efficient electromagnetic interference shielding properties (reaching more than 30 dB at a thickness of 2.0 mm), protecting electronics and humans from electromagnetic radiation and pollution. Therefore, the presented work represents a versatile strategy for developing environmentally friendly conductive hydrogels, demonstrating the perspectives of intelligent hydrogels for multifunctional applications.

Enzymatically synthesized γ-[Glu](n≥1)-Gln as novel calcium-binding peptides to deliver calcium with enhanced bioavailability

Novel γ-[Glu](n≥1)-Gln-Ca chelates were prepared by using γ-[Glu](n≥1)-Gln (mixture peptides containg γ-Glu-Gln, γ-Glu-Glu-Gln, γ-Glu-Glu-Glu-Gln, γ-Glu-Glu-Glu-Glu-Gln, γ-Glu-Glu-Glu-Glu-Glu-Gln) which were synthesized by glutaminase. Based on single factor and orthogonal array experiments, the optimal calcium-chelation conditions were as follows: 30 min chelation at 70 °C; peptide concentration, 0.15 g/mL; mixture peptides-to-calcium mass ratio, 25:1. The particle size of chelates was 743.6 ± 64.2 nm and the chelates appeared stable neutral molecular entities with 91.33% of chelation rate and 35.2 mg/g of calcium, also with higher thermostability. Chelated calcium ions might be surrounded by coordination bonds linking to two or more connecting points: oxygen atoms (carboxyl oxygen, hydroxyl oxygen and oxygen of peptide bonds) and nitrogen atoms (amino nitrogen). The chelates could be used for food/nutraceutical applications, as no toxicity at 0.125–10 mg/mL and enhanced efficiency in calcium release (releasing percentage over 85% at pH 8.0), transport and uptake compared with CaCl2 were detected in Caco-2 cells.

A Quality Analysis of Bony Specimens for Optimal Ethylenediaminetetraacetic Acid (EDTA) Decalcification.

Introduction: Weak acids, such as etheylenediaminetetraacetic acid (EDTA), chelate calcium ions from the surface of tissues, decalcifying slowly but preserving molecular structures for ancillary testing. There is a need for optimization of EDTA protocols for specimen decalcification. We studied the effects of EDTA on different types of bony specimens for quality assurance. Methods: Specimens included: proximal femur curettage (0.7 g), fibula shave (1 mm thick, 0.5 g), tibia shave (2 mm thick, 0.9 g), and femur 11-gauge core biopsies. Curettage and shave specimens were placed in formalin then EDTA (Newcomersupply, Middleton, WI, USA) with continuous stirring. Specimens were removed at 24, 48, 72, 96, and 120 hours. Core biopsies were processed in EDTA with heat at 4, 8, 12, and 16 hours. X-ray imaging (Kubtec Xpert 40, Stratford, CT, USA) was obtained. Histological processing was attempted and H&E slides compared to radiologic imaging. Results: Fibula and tibia sections showed appropriate radiolucency at 120 hours and 7 days, respectively. Curettage specimens showed radiolucency of medullary bone at 48 hours. Curettage and fibula sections showed quality histology at 96 hours and 120 hours, respectively. Quality tibia sections were obtained at 7 days, requiring one hour of additional block surface decalcification with 1% HCL solution. Medullary and cortical core biopsies showed quality histology at 12 and 16 hours with heat, respectively. Conclusion: Imaging can determine appropriate decalcification of bony specimens. Medullary bone undergoes more rapid decalcification in EDTA than cortical bone. EDTA decalcification is best used for curettage and core biopsy specimens.

Effect of protein peptides with different molecular weights on the setting and hydration process of gypsum

A series of protein retarders were prepared by hydrolyzing gelatin (Gel: Mw = 68020 g/mol; Gel-3: Mw = 40777 g/mol; Gel-6: Mw = 11951 g/mol and Gel-9: Mw = 7785 g/mol), and then the effects of these protein retarders on the setting and hydration process of gypsum were investigated in this paper. With the decreasing molecular weight of the protein retarder, the retarding effect on gypsum increased, while the negative impact on the strength and crystal morphology was more significant. The presence of a low-molecular-weight protein retarder more effectively delayed the increase in hydration degree of gypsum. FTIR and XRD analysis indicated that the formation of hydration product (gypsum dihydrate) was inhibited due to the addition of protein retarder. Moreover, this inhibition was more remarkable when a protein retarder with a lower molecular weight was introduced. Furthermore, we discovered that low-molecular-weight protein retarder with more carboxyl groups more easily chelated calcium ions in the gypsum paste, thereby more effectively inhibiting the hydration reaction of gypsum hemihydrate. In general, the molecular weight of the protein retarder plays an important role in gypsum retardation.

Apatite Formation Induced by Chitosan/Gelatin Hydrogel Coating Anchored on Poly(aryl ether nitrile ketone) Substrates to Promote Osteoblastic Differentiation.

Bone-like apatite is a promising coating of poly(ether ether ketone) (PEEK) for bone implantation. Poly(aryl ether nitrile ketone) containing phthalazinone moiety (PPENK) is a novel alternative for its easy synthesis. Here, chitosan/gelatin hybrid hydrogel coating is applied to induce the formation of apatite on the surface of PPENK substrate through biomineralization to improve its biocompatibility and osteogenic property. PPENK possessing allyl groups (PPENK-d) are synthesized and spin-coated on PPENK substrate to impart reactive groups. The hydrogel coating is prepared by the ultraviolet crosslinking of gelatin methacrylate (GelMA) and chitosan methacrylate (CSMA) on PPENK substrate. PPENK-d, GelMA, and CSMA are characterized by 1 H-NMR to confirm the designed structures. The presence of chitosan increases the chelation of calcium ions and thus induces the nucleation of apatite. The microstructural and compositional results reveal that the chitosan-containing hydrogel coating induced apatite coating yields a higher apatite quantity compared to the gelatin hydrogel coating. The apatite coatings on PPENK substrate promote the cytocompatibility and osteogenesis of MC3T3-E1 preosteoblasts in vitro.

Intracellular oxidative stress induced by calcium influx initiates the activation of phagocytosis in keratinocytes accumulating at S-phase of the cell cycle after UVB irradiation

BackgroundPhagocytosis is an essential process that maintains cellular homeostasis. In the epidermis, the phagocytosis of melanosomes into keratinocytes is important to protect their DNA against damage from ultraviolet B (UVB) radiation. Furthermore, it is considered that UVB activates the phagocytosis by keratinocytes but the detailed mechanism involved is not fully understood. ObjectiveTo clarify the mechanism of UVB-enhanced phagocytosis in keratinocytes, we investigated the relationship between the phagocytic ability of keratinocytes and the cell cycle stage of keratinocytes. MethodsThe phagocytic ability of keratinocytes was evaluated using the incorporation of fluorescent beads after exposure to UVB or oxidative stress. S-phase was evaluated by BrdU incorporation and immunostaining of cyclin D1. Intracellular calcium levels of keratinocytes were measured using the probe Fluo-4AM. ResultsThe phagocytosis of fluorescent beads into keratinocytes was enhanced by UVB and also by oxidative stress. We found that keratinocytes exposed to UVB or oxidative stress were at S-phase of the cell cycle. Furthermore, keratinocytes synchronized to S-phase showed a higher phagocytic ability according to the increased intracellular ROS level. The UVB-enhanced phagocytosis and entrance into S-phase of keratinocytes was abolished by ascorbic acid, a typical antioxidant. Keratinocytes synchronized to S-phase and exposed to UVB or oxidative stress had increased levels of intracellular calcium and their enhanced phagocytic abilities were diminished by the calcium ion chelator BAPTA-AM. ConclusionTaken together, intracellular oxidative stress induced by intracellular calcium influx mediates the UVB-enhanced phagocytic ability of keratinocytes accumulating at S-phase of the cell cycle.

Caffeine increased progressive motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples and enhanced activity of seminal creatine kinase.

Even though the effect of caffeine on humans' health has been revealed in various research studies, its effect on semen quality has yet to be well explained. Here, we measured the effect of caffeine at 1, 5, 10 and 20mM on motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples, level of seminal nitric oxide, chelation of seminal calcium ions and activity of seminal creatine kinase. Fifty-one normozoospermic and ten asthenozoospermic semen samples were recruited in this study. Sperm motility was evaluated by Makler counter, and seminal nitric oxide, seminal-free calcium and activity of seminal creatine kinase were measured spectrophotometrically. Caffeine at 10mM significantly (p<.05) increased progressive motility of spermatozoa in both tested groups. Also, caffeine significantly increased (p<.05) activity of creatine kinase and insignificantly (p>.05) altered nitric oxide and free calcium levels in seminal plasma. In conclusion, progressive motility of human spermatozoa was found to be higher in the presence of caffeine at 10mM in normozoospermic and asthenozoospermic semen samples; this increase, albeit partially, could be due to increased activity of seminal creatine kinase, but not to increased production of nitric oxide or chelation of free calcium ions.

Engineering a near-infrared nanosensor based on supramolecular self-assembly for Ca2+ detection and imaging in living cells and mice

Calcium ion (Ca2+) has proven to be the second messenger that is directly related to diverse normal biochemical functions and pathological processes. Thus, understanding the critical functions and dynamics of endogenous Ca2+ at cellular and animal levels is highly demanded. However, reliable fluorescence detecting and imaging strategies are usually challenging to achieve with high sensitivity, low background signal, and high imaging resolution for Ca2+ detecting and imaging analysis in vivo. Inspired by supramolecular self-assembly strategy, we herein report a novel supramolecular near-infrared (NIR) fluorescent nanosensor (NIRCD-Ca) for Ca2+ detecting and imaging analysis in vitro and in vivo with three parts: a guest NIR-fluorophore was labeled an adamantane moiety, a host supramolecular equipped with β-CD polymers, and a calcium ion chelating site of O,O'-Bis(2-aminophenyl)ethyleneglycol-N,N,N',N'-tetraacetic acid (BAPTA) as a fluorescence quenching moiety by photoinduce electron transfer effect (PET-effect). In the present work, NIRCD-Ca exhibits excellent water solubility and biocompatibility, very low background fluorescence with a significant ∼18-fold fluorescence intensity enhancement in the presence of Ca2+, superb resolution for mice imaging by NIR-emission, as well as extreme low detection line as low as 9.7 nM. All these features are favorable for detecting of Ca2+ in complex biological samples and applying for NIR imaging of Ca2+ in mouse model directly with satisfactory sensitivity, suggesting that the NIRCD-Ca is an ideal effective nanosensor for Ca2+ detecting and imaging analysis in biosystems. Furthermore, the nanosensor NIRCD-Ca has potentiality to become an essential detection technique for the investigation of signaling pathways involving Ca2+ in biosystems.

Fraxetin Suppresses Cell Proliferation and Induces Apoptosis through Mitochondria Dysfunction in Human Hepatocellular Carcinoma Cell Lines Huh7 and Hep3B.

Fraxetin is a coumarin scaffold compound extracted from Fraxinus rhynchophylla. It has antioxidant, anti-inflammatory, hepatoprotective, and antifibrotic effects. Furthermore, fraxetin has anticancer effects in breast and lung cancer. We aimed to evaluate whether fraxetin has anticancer activity in hepatocellular carcinoma (HCC) cells and its underlying mechanism. We demonstrated the anticancer effects of fraxetin in the HCC cell lines Huh7 and Hep3B. We confirmed that fraxetin inhibited cell proliferation (42% ± 10% Huh7; 52% ± 7% Hep3B) by arresting the cell cycle and inducing apoptosis in both cell lines. Moreover, fraxetin increased reactive oxygen species production (221% ± 55% Huh7; 460% ± 73% Hep3B), depolarized the mitochondrial membranes (ΔΨm) (345% ± 160% Huh7; 462% ± 140% Hep3B), and disrupted calcium homeostasis in both HCC cell lines. Chelating calcium ions with BAPTA-AM restored proliferation in fraxetin-treated Huh7 cells but not in Hep3B cells. Fraxetin did not affect the phosphorylation of extracellular-signal-regulated kinase 1/2, whereas it decreased JNK and phosphoinositide 3-kinase signaling. Furthermore, fraxetin and mitogen-activated protein kinase pharmacological inhibitors had synergistic antiproliferative effects on HCC cells. Although our study was limited to in vitro data that require validation, we suggest that fraxetin is a potential therapeutic agent against HCC progression.

Controlling the adsorption of mineral porous particles by chelation

Problem formulating. To increase the sorption capacity of calcium carbonate microparticles used as core for the development of targeted drug delivery, EDTA chelation of calcium ions was used to form a developed active surface of the particles. Goal. Is in modification of the surface of micron and submicron calcium carbonate vaterite particles using EDTA chelation of calcium ions and studying the effect of particle processing on their sorption capacity. Result. It was shown using scanning electron microscopy that EDTA treatment of the CaCO3 surface leads to an increase on the surface roughness of the particles, as well as an increase on their sorption capacity according to spectrophotometric data. Practical meaning. Use of adsorption to encapsulate the active substance inside the carriers. It is shown that an increase in the sorption capacity of particles leads to an increase in the amount of a substance inside its volume.

Calcium Ion Chelation Preserves Platelet Function During Cold Storage.

Platelet transfusion is a life-saving therapy to prevent or treat bleeding in patients with thrombocytopenia or platelet dysfunction. However, for >6 decades, safe and effective strategies for platelet storage have been an impediment to widespread use of platelet transfusion. Refrigerated platelets are cleared rapidly from circulation, precluding cold storage of platelets for transfusion. Consequently, platelets are stored at room temperature with an upper limit of 5 days due to risks of bacterial contamination and loss of platelet function. This practice severely limits platelet availability for transfusion. This study is to identify the mechanism of platelet clearance after cold storage and develop a method for platelet cold storage. Approach and Results: We found that rapid clearance of cold-stored platelets was largely due to integrin activation and apoptosis. Deficiency of integrin β3 or caspase-3 prolonged cold-stored platelets in circulation. Pretreatment of platelets with EGTA, a cell impermeable calcium ion chelator, reversely inhibited cold storage-induced platelet activation and consequently prolonged circulation of cold-stored platelets. Moreover, transfusion of EGTA-treated, cold-stored platelets, but not room temperature-stored platelets, into the mice deficient in glycoprotein Ibα significantly shortened tail-bleeding times and diminished blood loss. Integrin activation and apoptosis is the underlying mechanism of rapid clearance of platelets after cold storage. Addition of a cell impermeable calcium ion chelator to platelet products is potentially a simple and effective method to enable cold storage of platelets for transfusion.

Investigation of migration and self-healing ability of ion chelator in cement-based materials by a novel method

Ion chelator can chelate calcium ions and migrate in cement-based materials to promote self-healing of cracks. This paper investigated the migration and self-healing abilities of ion chelator in cement-based materials by a novel method. In this method, control mortar without ion chelator and self-healing mortar with ion chelator are poured into the same mold, cracks at different locations of the two kinds of mortars are prefabricated, and the migration of ion chelator from self-healing mortar to the control mortar is assessed by observing the self-healing process of crack in control mortar. Meanwhile, the microstructure and chemical component of self-healing product in cracks at different locations of the control mortar was characterized through scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the self-healing ability of control mortar is closely related to the migration distance of ion chelator. When the migration distance of the ion chelator was 2 cm, the crack with a width of 0.37 mm can be sealed after curing for 7 d. When the migration distance of the ion chelator was 5 cm, the crack with a width of 0.26 mm can also be repaired after curing for 7 d. Through SEM observation and XRD analysis, it can be found that the ion chelator promotes the formation of a large number of calcite crystals for sealing the cracks in the control mortar. However, the calcite crystals at the crack will become loose with the increase of the migration distance of the ion chelator.

Influence of calcium ions on physical chemical characteristics of semiconductor quantum dots encapsulated by amphiphilic polymer and their efficiency of cellular uptake

Here, we studied the effect of calcium ions on the physicochemical properties and cellular uptake of CdSe/ZnS quantum dots encapsulated with poly(maleic anhydride-alt-1-tetradecene), modified to a varying extent by quaternary ammonium groups. It was shown that quantum dots carrying negatively charged carboxyl groups in the polymer shell change their physicochemical and optical characteristics in the presence of Ca2+ and Ba2+ ions. As the negatively charged carboxyl groups in the shell are completely replaced by positively charged quaternary ammonium groups, these effects gradually decrease. A change in the physicochemical properties of nanoparticles leads to a change in their cellular uptake in the presence of calcium ions. Nanoparticles carrying only negatively charged groups in the shell in the presence of Ca2+ agglomerate and form conglomerates of nanoparticles and cells. The positively charged quaternary ammonium groups in the polymer shell of the nanoparticles increase their aggregative stability in the presence of Ca2+ and contribute to their uptake by cells. The mechanisms of uptake depend on nanoparticle’s charge. Nanoparticles with a positive ζ potential are absorbed by calcium-dependent mechanisms, which are suppressed by inhibition of the calcium-dependent enzyme dynamin or in the presence of calcium chelator EGTA. The uptake of nanoparticles with a negative ζ potential, in contrast, is enhanced by the chelation of calcium ions. This indicates the different role of cellular calcium-dependent mechanisms in the uptake of positively and negatively charged nanoparticles.

Using EDTA-2Na to inhibit sulfate attack in slag cement mortar under steam curing

This paper explored a novel method to inhibit sulfate attack in slag cement mortar under steam curing, by using ethylenediaminetetraacetic acid disodium (EDTA-2Na) to chelate calcium ions. 0.5 and 1% EDTA-2Na were used in slag cement mortars to evaluate the inhibition effect in sulfate solution (7.5% Na2SO4 and MgSO4 solution) for 360 days. The weight variation, compressive strength, along with FT-IR spectroscopy, XRD and DTG, were conducted to analyze the sulfate degradation. Additionally, the isothermal calorimetry was measured to study the effect of EDTA-2Na on the hydration of cement. Results indicated that 1% EDTA-2Na retarded the cement hydration distinctly. The EDTA-2Na enhanced the resistance of steam-cured slag mortar against sulfate attack. For the Na2SO4 attack, the enhancing effect of 1% EDTA-2Na was higher than that of 0.5% EDTA-2Na. For the MgSO4 attack, 0.5 and 1% EDTA-2Na was both beneficial. The EDTA-2Na decreased the amount of calcium hydroxide due to the chelation, retarding the formation of gypsum and secondary ettringite.

Sandstone Acidizing Using a Low-Reaction Acid System

Abstract Sandstone acidizing is the process of removing the damage from sandstone reservoirs to restore the well productivity/injectivity to its original or expected rates. It differs from carbonate acidizing in which a substantial portion of the rock is dissolved. Stimulating sandstone with mud acid HF/HCl may cause many problems as sandstone is a clastic sedimentary rock that consists mainly of quartz, silica minerals, feldspars, clays, and minor quantities of zeolite and chlorites. When conventional mud acid reacts with rock some sensitive components of sandstone get cemented by silica, calcite, or iron oxides. This happens due to the different precipitation reactions that take place and form fluosilicates, calcium fluorides, silica-gel filming, and even colloidal silica-gel compounds. In this work, two chelating agents, hydroxyethylenediaminetetraacetic acid (HEDTA) and diethylenetriaminepentaacetic acid (DTPA), were used to stimulate Berea sandstone cores. Berea sandstone cores were scanned using the XRD to quantify their mineralogical composition. Different pore volumes of 0.6M HEDTA and 0.6M DTPA were used as a preflush followed by different concentrations of HF as a main flush. For the post-flush stage, ammonium chloride was used to flow back the cores and measure their permeability. The levels of calcium, magnesium, aluminum, and iron ions in the effluent samples were measured using inductively coupled plasma (ICP) to assess the ability of each chemical to leach these different ions. Both HEDTA and DTPA showed a strong capability of chelating calcium, iron, and magnesium ions from the sandstone cores while the amounts of chelated aluminum ions were quite small. Once starting the injection of the used chelating agents, the permeability of the core got enhanced gradually. The higher amounts of the chelating agents resulted in better the cores permeability. However, DTPA showed a better permeability enhancement than HEDTA due to its stronger ability to chelate the calcium, iron, magnesium, and aluminum ions. Adding HF as the main flush initiates different reactions with the clay and silica minerals of the Berea sandstone cores. This caused a reduction in the permeability due to the formation of some precipitates such as fluosilicates and calcium fluorides. Therefore, it is recommended to use a very low concentration of HF while treating the Berea sandstone.

Effect of Microwave Irradiation Nonuniformity on the Digestion and Allergenicity of the Glycated Ovalbumin

The glycated OVA by microwave irradiation was digested by different methods (gastric digestion, intestinal digestion, and two-step digestion). Digestibility properties change of glycated OVA after digestion were evaluated in this work. The results showed that the samples were mainly digested in the stomach and they were hardly hydrolyzed by trypsin. Glycated OVA digested in stomach or in intestines produced more free amino groups than that by two-step digestion. Calcium ion chelating ability of glycated OVA was much higher than OVA when digested in stomach and intestines; glycated OVA had stronger ferrous ion chelating abilities by intestinal digestion. Glycated OVA after being digested hold the better antioxidant activity than the digested OVA, especially the Sample 3. IgG and IgE binding of all samples after intestinal digestion and two-step digestion were lower than that by gastric digestion. The IgG binding of glycated OVAs were lower than OVA, the result of the IgE binding was the opposite.