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In this work, we performed static density functional theory calculations and ab initio metadynamics simulations to systematically investigate the association mechanisms and dynamic structures of four kinds of ion pairs that could be formed before the nucleation of CaCO3. For Ca2+– H C O 3 − and Ca2+– C O 3 2 − pairs, the arrangement of ligands around Ca2+ evolves between the six-coordinated octahedral structure and the seven-coordinated pentagonal bipyramidal structure. The formation of ion pairs follows an associative ligand substitution mechanism. Compared with H C O 3 − , C O 3 2 − exhibits a stronger affinity to Ca2+, leading to the formation of a more stable precursor phase in the prenucleation stage, which promotes the subsequent CaCO3 nucleation. In alkaline environments, excessive OH− ions decrease the coordination preference of Ca2+. In this case, the formation of Ca(OH)+– C O 3 2 − and Ca(OH)2– C O 3 2 − pairs favors the dissociative ligand substitution mechanism. The inhibiting effects of OH− ion on the CaCO3 association can be interpreted from two aspects, i.e., (1) OH− neutralizes positive charges on Ca2+, decreases the electrostatic interactions between Ca2+ and C O 3 2 − , and thus hinders the formation of the CaCO3 monomer, and (2) OH− decreases the capacity of Ca2+ for accommodating O, making it easier to separate Ca2+ and C O 3 2 − ions. Our findings on the ion association behaviors in the initial stage of CaCO3 formation not only help scientists evaluate the impact of ocean acidification on biomineralization but also provide theoretical support for the discovery and development of more effective approaches to manage undesirable scaling issues. [ABSTRACT FROM AUTHOR]

It is significant to investigate the calcium carbonate (CaCO3) precipitation mechanism during the carbon capture process; nevertheless, CaCO3 precipitation is not clearly understood yet. Understanding the carbonation mechanism at the atomic level can contribute to the mineralization capture and utilization of carbon dioxide, as well as the development of new cementitious materials with high-performance. There are many factors, such as temperature and CO2 concentration, that can influence the carbonation reaction. In order to achieve better carbonation efficiency, the reaction conditions of carbonation should be fully verified. Therefore, based on molecular dynamics simulations, this paper investigates the atomic-scale mechanism of carbonation. We investigate the effect of carbonation factors, including temperature and concentration, on the kinetics of carbonation (polymerization rate and activation energy), the early nucleation of calcium carbonate, etc. Then, we analyze the local stresses of atoms to reveal the driving force of early stage carbonate nucleation and the reasons for the evolution of polymerization rate and activation energy. Results show that the higher the calcium concentration or temperature, the higher the polymerization rate of calcium carbonate. In addition, the activation energies of the carbonation reaction increase with the decrease in calcium concentrations. [ABSTRACT FROM AUTHOR]

Mineral-polymer composites found in nature exhibit exceptional structural properties essential to their function, and transferring these attributes to the synthetic design of functional materials holds promise across various sectors. Biomimetic fabrication of nanocomposites introduces new pathways for advanced material design and explores biomineralization strategies. This study presents a novel approach for producing single platelet nanocomposites composed of CaCO3 and biomimetic peptoid (N-substituted glycines) polymers, akin to the bricks found in the brick-and-mortar structure of nacre, the inner layer of certain mollusc shells. The significant aspect of the proposed strategy is the use of organic peptoid nanosheets as the scaffolds for brick formation, along with their controlled mineralization in solution. Here, we employ the B28 peptoid nanosheet as a scaffold, which readily forms free-floating zwitterionic bilayers in aqueous solution. The peptoid nanosheets were mineralized under consistent initial conditions (σcalcite = 1.2, pH 9.00), with variations in mixing conditions and supersaturation profiles over time aimed at controlling the final product. Nanosheets were mineralized in both feedback control experiments, where supersaturation was continuously replenished by titrant addition and in batch experiments without a feedback loop. Complete coverage of the nanosheet surface by amorphous calcium carbonate was achieved under specific conditions with feedback control mineralization, whereas vaterite was the primary CaCO3 phase observed after batch experiments. Thermodynamic calculations suggest that time-dependent supersaturation profiles as well as the spatial distribution of supersaturation are effective controls for tuning the mineralization extent and product. We anticipate that the control strategies outlined in this work can serve as a foundation for the advanced and scalable fabrication of nanocomposites as building blocks for nacre-mimetic and functional materials.

Calcium carbonate (CaCO3) is abundant on Earth, is a major component of marine biominerals and thus of sedimentary and metamorphic rocks and it plays a major role in the global carbon cycle by storing atmospheric CO2 into solid biominerals. Six crystalline polymorphs of CaCO3 are known-3 anhydrous: calcite, aragonite, vaterite, and 3 hydrated: ikaite (CaCO3·6H2O), monohydrocalcite (CaCO3·1H2O, MHC), and calcium carbonate hemihydrate (CaCO3·½H2O, CCHH). CCHH was recently discovered and characterized, but exclusively as a synthetic material, not as a naturally occurring mineral. Here, analyzing 200 million spectra with Myriad Mapping (MM) of nanoscale mineral phases, we find CCHH and MHC, along with amorphous precursors, on freshly deposited coral skeleton and nacre surfaces, but not on sea urchin spines. Thus, biomineralization pathways are more complex and diverse than previously understood, opening new questions on isotopes and climate. Crystalline precursors are more accessible than amorphous ones to other spectroscopies and diffraction, in natural and bio-inspired materials.

Hollow vaterite microspheres are important materials for biomedical applications such as drug delivery and regenerative medicine owing to their biocompatibility, high specific surface area, and ability to encapsulate a large number of bioactive molecules and compounds. We demonstrated that hollow vaterite microspheres are produced by an Escherichia coli strain engineered with a urease gene cluster from the ureolytic bacteria Sporosarcina pasteurii in the presence of bovine serum albumin. We characterized the 3D nanoscale morphology of five biogenic hollow vaterite microspheres using 3D high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) tomography. Using automated high-throughput HAADF-STEM imaging across several sample tilt orientations, we show that the microspheres evolved from a smaller more ellipsoidal shape to a larger more spherical shape while the internal hollow core increased in size and remained relatively spherical, indicating that the microspheres produced by this engineered strain likely do not contain the bacteria. The statistical 3D morphology information demonstrates the potential for using biogenic calcium carbonate mineralization to produce hollow vaterite microspheres with controlled morphologies. STATEMENT OF SIGNIFICANCE: The nanoscale 3D structures of biomaterials determine their physical, chemical, and biological properties, however significant efforts are required to obtain a statistical understanding of the internal 3D morphology of materials without damaging the structures. In this study, we developed a non-destructive, automated technique that allows us to understand the nanoscale 3D morphology of many unique hollow vaterite microspheres beyond the spectroscopy methods that lack local information and microscopy methods that cannot interrogate the full 3D structure. The method allowed us to quantitatively correlate the external diameters and aspect ratios of vaterite microspheres with their hollow internal structures at the nanoscale. This work demonstrates the opportunity to use automated transmission electron microscopy to characterize nanoscale 3D morphologies of many biomaterials and validate the chemical and biological functionality of these materials.

The present study aims to optimize Cereplast composite materials' mechanical properties, using vine fibers as a reinforcing filler and calcium carbonate as a non-reinforcing filler. The composite samples were prepared in two steps. The first step involves extruding the different mixtures to obtain the granules. A twin-screw rotary cone extruder was used to make different composite formulations. The second step involves manufacturing the standardized specimens using a plastic injection press. Incorporating 20% and 40% vine fibers in the Cereplast matrix increased Young's modulus by 81.5 and 197.9%, respectively. However, the values obtained with calcium carbonate were much lower than those obtained with vine fibers. The tensile strength decreased with an increasing load content due to poor interfacial interaction between the fillers and matrix. The stiffness and brittleness of the composites increased with the loading rate, which reduced the composites' elasticity and led to lower elongation at break. A cross mixture design containing 13 trials has been set up and explored to study the effect of mixing proportions of polymers, vine fiber, and calcium carbonate on the synthesized composites. A three-component constrained mix design can limit the number of experiments to arrive quickly at the optimal mix design. The results of the mixing plane analysis showed that the second-degree model fits well and has good quality. The model correctly described the variation of Young's modulus with the proportions of the mixtures. Thus, increasing the contents of both fillers increases Young's modulus, but vine fibers' effect is more pronounced than calcium carbonate. [ABSTRACT FROM AUTHOR]

Today, the rise of opportunistic infections and their resistance to current antifungal drugs has led to the inevitable need to produce effective antimicrobials at a reasonable cost. This study aimed at producing a calcium carbonate/cobalt oxide nanocomposite with the most excellent antifungal activity against Candida albicans (C. albicans). Thus, nine experimental designs using the Taguchi technique were utilized to discover the greatest combination of parameters for antifungal activity. The colony‐forming unit (CFU) method was used to test the produced nanocomposites' antifungal properties against C. albicans. The results indicated that the synthesized nanocomposite in optimal conditions (20 mg/mL of calcium carbonate, 3 mg/mL of cobalt oxide, and 90 min of stirring time) could inhibit the growth of C. albicans by more than 74%. Various analyses were applied to determine the structural properties of the calcium carbonate/cobalt oxide nanocomposite, and its constituents revealed the fabricated nanocomposite's desirable properties. In the study, the nanocomposite was an efficient antifungal agent that might be employed in various fields, including medicine, dentistry, and life sciences. [ABSTRACT FROM AUTHOR]

This study shows how bacterial viruses (bacteriophages, phages) interact with calcium carbonate during precipitation from aqueous solution. Using electron microscopy, epifluorescence microscopy, X-ray diffraction, and image analysis, we demonstrate that bacteriophages can strongly influence the formation of the vaterite phase. Importantly, bacteriophages may selectively bind both amorphous calcium carbonate (ACC) and vaterite, and indirectly affect the formation of structural defects in calcite crystallites. Consequently, the surface properties of calcium carbonate phases precipitating in the presence of viruses may exhibit different characteristics. These findings may have significant implications in determining the role of bacterial viruses in modern microbially-rich carbonate sedimentary environments, as well as in biomedical technologies. Finally, the phage-vaterite system, as a biocompatible material, may serve as a basis for the development of promising drug delivery carriers. [ABSTRACT FROM AUTHOR]

In the article by Thomson and colleagues ([1]), the authors identified an error in the description of the calcium dose in the abstract and first paragraph and under Randomization and Interventions in the Methods section. In the abstract and Methods section, the text reads "1000 mg of calcium carbonate (400 mg of elemental calcium)." In the first paragraph, the text reads "(1000 mg of calcium [400 mg of elemental calcium])." It should read "1000 mg of elemental calcium as calcium carbonate." The text has been corrected in all places. [Extracted from the article]

In the present study, the undrained cyclic behaviour of biotreated sands using microbial and enzyme-induced carbonate precipitation was investigated for a wide range of initial void ratio after consolidation ( e 0 ), initial effective normal stress ( σ N 0 ′ ) and calcium carbonate content (CC) under direct simple shear (DSS) testing conditions. The critical state soil mechanics framework for untreated sand was first established using a series of drained and undrained (constant volume) tests, which served as a benchmark for evaluating the undrained cyclic liquefaction behaviour of untreated and biotreated sands. The results indicated that the modified initial state parameter ( ψ m 0 ) in DSS condition showed a good correlation with instability states and phase transformation under monotonic shearing. In undrained cyclic DSS loading condition, samples displayed cyclic mobility indicated by an abrupt accumulation of large strain or σ N 0 ′ transiently reaching zero or a sudden build-up of excess pore water pressure. The linkage between static and cyclic liquefaction was established for untreated and biotreated sand specimens based on the equivalence of characteristic soil states. The number of cycles before liquefaction (NL) for the biotreated sand specimens was mainly controlled by the cyclic stress ratio, e 0 , σ N 0 ′ and CC. For a similar initial state prior to undrained cyclic loading, the biotreated specimens required a larger NL compared to the untreated sand. The cyclic resistance ratio at NL = 15 (CRR15) increased with decreasing ψ m 0 for the untreated sand, while the CRR15 for biotreated sand increased with increasing CC and decreasing σ N 0 ′ . [ABSTRACT FROM AUTHOR]

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Objectives: Our aim was to predict the prevalence of osteopenia and osteoporosis and their associated risk factors among postmenopausal women from Jordan. Methodology: In this cross‐sectional study, a total of 368 postmenopausal women were recruited from King Abdullah University Hospital (KAUH) in the North of Jordan between September 2022 and April 2023. Bone mineral density (BMD) was measured using a dual‐energy X‐ray absorptiometry scan. T‐score was used for osteoporosis diagnosis in accordance with the International Society for Clinical Densitometry (ISCD) guidelines. Data about sociodemographic and lifestyle variables were collected using face‐to‐face interviews. Medical records were used to retrieve participants' BMD information. Predictors of osteoporosis were identified using logistic regression. Results: Prevalence of osteoporosis was 40.5%, while 44.6% of participants were diagnosed with osteopenia. The lumbar spine had the highest frequency of osteoporosis (30.4%), while the left femoral neck had the highest prevalence of osteopenia (46.3%). Postmenopausal women's age (p‐value =.024), and history of chronic diseases (p‐value =.038) were significant factors associated with increased osteoporosis risk. Conclusions: Postmenopausal women from Jordan had high prevalence of osteoporosis and osteopenia. It is therefore necessary to target risk factors leading to osteoporosis and to improve patients' lifestyles through patient education. Healthcare systems should consider early screening approaches for osteoporosis at the age of menopause and thereafter. Supplements of calcium and vitamin D may be routinely considered for this age group depending on their serum levels. [ABSTRACT FROM AUTHOR]

In this paper, a new gram scale experiment with well characterised boundary conditions is proposed for pyrolysis experiments. The set-up consists of a tube furnace, based on ISO19700, with a newly designed concept for a balance within the oven, allowing for online mass loss measurements. Samples with a length up to 50 cm can be investigated in this apparatus. The oven allows for experiments at fixed temperatures or at fixed heating rates, under controlled atmosphere, w.r.t. gas composition and flow rate. A thorough characterisation of the set-up is presented, including aspects like reproducibility of the heating rate or the precision of the balance. The functionality of the balance has been demonstrated with calcium carbonate (CaCO 3 ) experiments. This material was chosen because it decomposes in a single reaction, which only releases CO 2 . This allows for comparison between the mass loss rate of the balance and the CO 2 production rate, measured by a gas analyser. Results for two different heating rates: 3 K/min and 5 K/min and for different masses (25 g and 8.5 g) are presented. The two measurement methods are in excellent agreement. Finally, the data obtained from the new experimental set-up is compared to results from thermogravimetric analyser (TGA) experiments. [ABSTRACT FROM AUTHOR]

Despite extensive works have been devoted to study the scale inhibition behavior, the performance of inhibitors is still not fully understood. In this paper, we present a laboratory study to elucidate the impact of water composition on the performance of some commonly used phosphonate and polymeric calcium carbonate scale inhibitors, in highly supersaturated brines at high temperature. Calcium tolerance inhibitor chemicals with various molecular structures are studied using dynamic scale loop test method at 150 °C. Brine composition is varied by changing the non-stoichiometry of scaling lattice ions, e.g., ( Ca 2 + ) / ( CO 3 2 − ) ratio, over a wide range. Test results indicate that the effectiveness of inhibitors can be significantly changed by the scaling ion ratio. In general, the efficacy of inhibitors decreases significantly with calcium concentration in the test brine even at constant supersaturation state and temperature, and also the performance ranking of the different inhibitor chemistries can be changed with brine composition. This could be caused by the alternations of interactions between inhibitor molecules and the surface of calcium carbonate scale crystals. Findings from this study suggest that the effect of scaling ion ratio must be considered in scaling risk assessment and for the optimization of inhibitor treatment programs. [ABSTRACT FROM AUTHOR]

Calcium hydroxide was used as a swelling agent and grinding aid to grind together with cellulose raw materials to prepare microfibrillated cellulose (MFC). Carbon dioxide was introduced to obtain MFC coated with calcium carbonate (CMFC). The effect of calcium hydroxide dosage on the fibrillation process of cellulose materials and the characteristics of MFCs and CMFCs were studied. Results show that when the dosage of calcium hydroxide was 5 % (based on cellulose materials), calcium hydroxide could be completely dissolved in water and had a swelling effect on cellulose materials. When the dosage reached 10 %, undissolved calcium hydroxide particles could serve as grinding media to assist in the fibrillation of cellulose materials. When the dosage exceeded 50 %, the auxiliary grinding effect of calcium hydroxide was more obvious. After accelerated carbonation, the generated calcium carbonate nanoparticles were coated on the surface of MFC, which increased its viscosity and decreased water retention value. The presence of calcium carbonate also facilitated the concentration, redispersion, and drying of MFC. The pretreatment, mechanical fibrillation, and accelerated carbonation were carried out in the same equipment without the need for heating or washing. Therefore, this study provides a in situ and one step method for the preparation of MFC. [ABSTRACT FROM AUTHOR]

In vitro biomineralization, carried out under laboratory conditions, provides scope for highly controlled crystallization events, at different stages of the formation reaction. This crystallization control is exerted using foreign substances or additives, which are usually organic compounds. Here, we have shown how with the use of homeopathic medicine Symphytum Q, the morphology of calcium carbonate is changed from its rhombohedral, the most stable morphology to spherical morphology, while the phase remains the same. A study has also been done on the formation of gypsum with varying parameters. [ABSTRACT FROM AUTHOR]

Several strategies can be used to treat skin injuries, among which the use of hydrogel-based dressings stands out due to its wet wound healing process. In this class, chitosan-based hydrogels stand out due to the good characteristics of this matrix, which include its high biocompatibility, antimicrobial activity, and ability to act as a carrier for local delivery of actives. Therefore, the objective of this work was to obtain chitosan hydrogel (CS) crosslinked with tripolyphosphate (TPP), containing calcium carbonate (CaCO3) from chicken eggshell and/or collagen tripeptide (Tcol) for regeneration of skin. To obtain the systems, the CS concentration was fixed at 1% m/m in relation to the acetic acid solution, and 1 and 2% m/m of (CaCO3) and/or 5% m/m of Tcol were used, both in relation to CS mass. The obtained systems were characterized in terms of physicochemical properties of the systems, Tcol release and cytocompatibility and cellular adhesion of L929 fibroblasts. The results indicated that there is no formation of chemical bonds and/or strong chemical interactions between the actives and the CS matrix. Furthermore, it was observed that the systems do not generate cytotoxicity to the L929 fibroblast lineage and have an average porosity of around 70% with pore sizes between 200 and 500 μm. The Tcol release profile of the systems showed an initial burst effect in the first two hours followed by a Tcol release for up to 20 h. The addition of Tcol did not change the degree of porosity, swelling and cytocompatibility of the gels, but it increased the cell adhesion of fibroblasts to the scaffold. CaCO3, in turn, tended to slightly reduce the porosity and swelling of the gels and generated a reduction in the Tcol release rate, without altering the biological properties of the hydrogels. Regarding the compressive strength of the systems, the presence of the Tcol active ingredient did not significantly alter the strength of the systems; however, calcium carbonate tended to increase the compressive strength of the evaluated systems by 7–11%. Based on the results obtained, chitosan-based gels containing CaCO3, and Tcol shows promise for application in skin wound regeneration. [ABSTRACT FROM AUTHOR]

We present a comparison of common electron microscopy sample preparation methods for studying crystallisation processes from solution using both scanning and transmission electron microscopy (SEM and TEM). We focus on two widely studied inorganic systems: calcium sulphate, gypsum (CaSO4·2H2O) and calcium carbonate (CaCO3). We find significant differences in crystallisation kinetics and polymorph selection between the different sample preparation methods, which indicate that drying and chemical quenching can induce severe artefacts that are capable of masking the true native state of the crystallising solution. Overall, these results highlight the importance of cryogenic (cryo)‐quenching crystallising solutions and the use of full cryo‐TEM as the most reliable method for studying the early stages of crystallisation. [ABSTRACT FROM AUTHOR]

Amidst the increasing significance of innovative solutions for bioremediation of heavy metal removal, this paper offers a thorough bibliometric analysis of microbial-induced carbonate precipitation (MICP) for heavy metal removal, as a promising technology to tackle this urgent environmental issue. This study focused on articles published from 1999 to 2022 in the Scopus database. It assesses trends, participation, and key players within the MICP for heavy metal sequestration. Among the 930 identified articles, 74 countries participated in the field, with China being the most productive. Varenyam Achal, the Chinese Academy of Sciences, and Chemosphere are leaders in the research landscape. Using VOSviewer and R-Studio, keyword hotspots like "MICP", "urease", and "heavy metals" underscore the interdisciplinary nature of MICP research and its focus on addressing a wide array of environmental and soil-related challenges. VOSviewer emphasises essential terms like "calcium carbonate crystal", while R-Studio highlights ongoing themes such as "soil" and "organic" aspects. These analyses further showcase the interdisciplinary nature of MICP research, addressing a wide range of environmental challenges and indicating evolving trends in the field. This review also discusses the literature concerning the potential of MICP to immobilise contaminants, the evolution of the research outcome in the last two decades, MICP treatment techniques for heavy metal removal, and critical challenges when scaling from laboratory to field. Readers will find this analysis beneficial in gaining valuable insights into the evolving field and providing a solid foundation for future research and practical implementation. [ABSTRACT FROM AUTHOR]

Microcellular foamed plant fiber composites have the advantages of low density, low cost, and biodegradability, so it has great development potential in the industry. Nevertheless, the existence of cellular structures diminishes the mechanical performance of plant fiber composites. To overcome this problem, in this study, nano‐CaCO3 was used to enhance the microcellular foamed plant fiber composites, and the three‐phase thermoplastic composites, comprised of nano‐CaCO3, rice‐husk fiber, and polypropylene (PP), were fabricated using a chemical foaming injection molding technique. The study analyzed how the nano‐CaCO3 concentration affected the melt viscosity, crystallization characteristics, mechanical properties, and cellular structure of the composites. According to the findings, the mechanical characteristics of microcellular foamed three‐phase thermoplastic composites were enhanced initially and subsequently diminished as the nano‐CaCO3 content was augmented, and obtained optimal value at 2 wt% nano‐CaCO3 content. By observing the cells of microcellular foamed three‐phase thermoplastic composites in vertical and parallel melt flow directions, it was found that the nano‐CaCO3 content of 2 wt% three‐phase thermoplastic composite had the best cellular structure. Highlights: The role of nano‐CaCO3 in plant fiber composite materials was explored.The relationship between the content of nano‐CaCO3 and the various properties of tri‐phasic plant fiber composite materials was demonstrated.The mechanisms by which nano‐CaCO3 enhances plant fiber composite materials were analyzed at both macroscopic and microscopic levels. [ABSTRACT FROM AUTHOR]

In this study, indigo carmine (IC)-calcium carbonate lakes with different crystalline forms of calcium carbonate were prepared through co-precipitation methods, and the properties of these lakes and their formation mechanisms were investigated. The results showed that amorphous calcium carbonate (ACC) exhibited the smallest particle size and the largest specific surface area, resulting in the highest adsorption efficiency. Vaterite, calcite, and aragonite followed after ACC in decreasing order of adsorption efficiency. Kinetic analysis and isothermal analysis revealed the occurrence of chemisorption and multilayer adsorption during formation of the lakes. The FTIR and Raman spectra suggested participation of sulfonic acid groups in chemisorption. Appearance of IC significantly altered TGA curves by changing weight loss rate before decomposition of calcium carbonate. EDS analysis revealed the adsorption of IC predominantly happened on the surface of calcium carbonate particles rather than the interior. [ABSTRACT FROM AUTHOR]

A series of microbial-induced carbonate precipitation (MICP) experiments were conducted using Sporosarcina pasteurii to reinforce coastal soft clay in Zhejiang. By analyzing the physical and mechanical parameters of samples of varying ages, specifically focusing on each sample's unconfined compressive strength, triaxial shear strength, and permeability coefficient, it was revealed that MICP technology can be used effectively to reinforce coastal clay. The unconfined compressive strength of treated soil increased by 23% compared to untreated soil, while the permeability coefficient decreased by 75%. The internal friction angle of the clay remained almost constant, whereas cohesion significantly increased by approximately 53%. One-dimensional compression experiments were also performed, yielding consolidation parameters such as the compression coefficient, compression index, and consolidation coefficient. The results indicated a notable decrease in the soil compression index. Furthermore, microscopic analysis revealed that clay particles were cemented by calcium carbonate, whose precipitation was induced by the bacteria. Our XRD results also indicated that the bacteria facilitated the conversion of Ca2+ present in the soil into calcium carbonate. [ABSTRACT FROM AUTHOR]

Globally, scale deposition in water supply pipelines is one of the major problems faced by water utilities. This research aimed to determine the causes and effects of scale deposition in the water supply pipelines in Surakarta City, Indonesia. The total dissolved solids (TDS), hardness, manganese, and alkalinity in groundwater were higher than those in the surface water and spring water; thus, the supply areas from groundwater were identified using TDS at the taps. The three scaling indicators, i.e., the Langelier saturation index (LSI), the Ryznar stability index (RSI), and the Puckorius scaling index (PSI), indicated moderate calcium carbonate scaling. However, elemental analysis of eight scale samples using X-ray fluorescence (XRF) revealed that the major components of scale were either manganese (50.1–80.8%) or iron (45.6–63.8%), whereas calcium (3.0–7.8%) was a minor component. Because only five of twenty groundwater sources were chlorinated before distribution, it is estimated that dissolved manganese is oxidized by manganese-oxidizing bacteria. The manganese deposition rate in the networks was estimated to be 1660 kg/year using the manganese concentration at groundwater sources and in customers' taps. These results suggest the importance of the elemental analysis of scale and avoidance of overreliance on scale indicators. [ABSTRACT FROM AUTHOR]

A nano-immunomodulator modified with N-acetylgalactosamine (GalNAc) on calcium carbonate (CaCO3) was prepared for targeted and responsive immunotherapy. And the immunologic adjuvant (CpG ODNs) and doxorubicin (DOX) were released to synergistically improve immune response for treating orthotopic liver cancer. [ABSTRACT FROM AUTHOR]

The limitations associated with conventional cancer treatment modalities, particularly for breast cancer, underscore the imperative for developing safer and more productive drug delivery systems. A promising strategy that has emerged is the combination of chemotherapy with gas therapy. We synthesized curcumin-loaded amorphous calcium carbonate nanoparticles (Cur-CaCO3) via a gas diffusion reaction in the present study. Subsequently, a "one-step" ethanol injection method was employed to fabricate lipid-coated calcium carbonate nanoparticles (Cur-CaCO3@LA-Lip) loaded with L-arginine, aimed at harnessing the synergistic effects of chemotherapy and nitric oxide to enhance antitumor efficacy. Transmission electron microscopy analysis revealed that Cur-CaCO3@LA-Lip nanoparticles were subspherical with a distinct lipid layer encapsulating the periphery. Fourier transform infrared spectroscopy, X-ray powder diffraction, and differential scanning calorimetry results confirmed the successful synthesis of Cur-CaCO3@LA-Lip. The nanoparticles exhibited significant drug loading capacities of 8.89% for curcumin and 3.1% for L-arginine. In vitro and in vivo assessments demonstrated that Cur-CaCO3@LA-Lip nanoparticles facilitated sustained release of curcumin and exhibited high cellular uptake, substantial tumor accumulation, and excellent biocompatibility. Additionally, the nanoparticles showed robust cytotoxicity and potent antitumor efficacy, suggesting their potential as a formidable candidate for breast cancer therapy. [ABSTRACT FROM AUTHOR]

Mineral weathering played a critical role in removing highly concentrated carbon dioxide (CO2) from the Precambrian atmosphere. Currently, it plays an important role in biogeochemical cycles and soil formation in terrestrial ecosystems. We aimed to fix CO2 by crystallizing carbonated minerals obtained from weathered rocks into calcium carbonate (CaCO3). In this study, we isolated a new Enterobacter bacteria (UT18) species from soil containing many rocks and plants by comparing the ability of the isolated bacteria to decrease pH. In combination with the results of high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS), we demonstrated that UT18 participates in mineral weathering by secreting gluconic acid and acetic acid. These organic acids can release Ca, Al, and Si from anorthite. Traces of weathering on the anorthite surface were observed using scanning electron microscopy (SEM). The released Ca ions can be recrystallized by the addition of Na2CO3 into the formation of CaCO3 in the form of aragonite. Our study describes a new characteristic of acid production in UT18 and demonstrates an example of an H+-releasing pattern in microbial mineral weathering. This study will help elucidate the mechanism of microbial mineral weathering and can be applied to soil improvement and greenhouse effect mitigation. [ABSTRACT FROM AUTHOR]

Bio-cementation of weathered soils of hilly regions using native ureolytic bacteria is a practical approach to improve soil strength. This study aimed to isolate and characterize native urease-producing bacterial strains from different slope failure regions of Uttarakhand, India, through multi-step screening, and showcased their potential in soil improvement. A total of 80 bacterial strains were isolated from thirteen landslide-prone sites to screen for potent native urease-producing strains. Interestingly, nine native strains exhibited high calcium carbonate precipitation (158–187 mg/10 ml) and urease activity (657–3495 µM/mL) compared to Sporosarcina pasteurii (NCIM 2477), a potent bacterium commonly used for bio-cementation. These strains belonged to various genera, including Lysinibacillus sp., Sporosarcina sp., Pseudochrobactrum sp., and Cytobacillus sp. Cohesionless soil samples treated with the native strains exhibited high unconfined compressive strength values ranging from 0.1 MPa to 1 MPa, whereas those treated with S. pasteurii were 0.15 MPa. The urease-producing bacterial strains with CaCO3 precipitation activity influenced the soil strength and failure patterns. FESEM, XRD, and acid-washing tests revealed that native bacterial strains precipitated CaCO3 more than S. pasteurii strain. The study explores, for the first time, the potential of native ureolytic bacteria from different regions of Uttarakhand, India, for soil strength enhancement. [ABSTRACT FROM AUTHOR]