Calcium Carbonate Crystals Research Articles

Experimental Study on the Crack Concrete Repaired via Enzyme-Induced Calcium Carbonate Precipitation (EICP).

A low-carbon and environmentally friendly EICP method for repairing concrete cracks is presented to prolong the service life of concrete. In this study, we took concrete as the research object and quartz sand as the filling medium and employed the EICP injection method to repair concrete cracks. The internal repair effect of EICP on concrete cracks was evaluated with a combination of ultrasonic and compressive strength tests. The concrete repair mechanism of EICP was identified with a combination of EDS, XRD, and SEM tests. The results indicate that with an increase in the fracture depth, the ultrasonic sound time of the crack specimen increased gradually, and the ultrasonic wave transit time value of the crack specimen decreased significantly after EICP repair. After repair, the compressive strength rose. The highest compressive-strength recovery rate of a 0.3 mm wide specimen is 98.41%. The calcium carbonate crystal formed using EICP is vaterite. The probability density function model of the Laplace distribution was constructed, which showed good applicability and consistency in the ultrasonic sound time and compressive strength measured via experiments. The formed calcium carbonate crystals can be tightly and evenly attached to the cracks with the EICP injection repair method, resulting in a better repair effect.

Isolation and Identification of Carbonoclastic Fungi Causing Damage to Prehistoric Paintings in the Maros-Pangkep Karst Area

The carbonoclastic fungi known as a fungi that can produce calcium carbonate crystals (CaCO3) through the urease enzyme produced to hydrolysis of urea contained in the substrate or growth medium. The presence of carbonoclastic fungi is frequently observed in the karst areas cave wall painting, which are a type of ancient artifact. The destruction to the ancient cave artwork is brought on by the fungus. The purpose of this study was to obtain and determine the types of carbonoclastic fungi that cause damage to cave wall paintings in the Maros-Pangkep karst area. Isolation and selection of carbonoclastic fungi were carried out using Christensen Urea Agar medium. The CaCO3 precipitate potential test was carried out by calculating the mass CaCO3 precipitates formed and analysis of ammonia levels and cell biomass produced during the growth period. Fungi identification was performed using the 18S rRNA gene molecular markers. Twenty four fungi isolates obtained from swab samples in Parewe and Bulu Sipong caves, 7 positive isolated belonged to carbonoclastic fungi. The results of CaCO3 precipitates, namely isolate Ps3 producing precipitates of 80,30 mg with ammonia content value of 701,7064 ppm and cell biomass of 333,80 mg. The identification results showed that Ps3 isolate belongs to Aspergillus sp. strain BW1.

A self-cleaning coating on copper for inhibiting calcium carbonate crystallization and scaling

To address the technical bottleneck of synergistic damage caused by corrosion and scaling after damage to protective coatings on heat exchangers, petrochemical pipelines, and seawater desalination equipment, the surface scaling amount and calcium carbonate crystal morphology of anti-corrosion polymer coating (expressed as ZF,WCA = 95°) and self-cleaning coating (expressed as ZQ,WCA = 120°, WSA = 14°) are compared in a scaling system involving metal ions (Fe2+) generated by corrosion. The anti-scaling effect of the ZQ coating (34.6 %) with ions is 61.7 % higher than that of the ZF coating (21.4 %). As the concentration of Fe2+ increases, the aragonite on the ZQ coating transform from needle shaped crystals to cactus shaped crystals (expressed as C-CaCO3) with their whisker length about 20 μm. Furthermore, Cu2+ is introduced into the system by galvanic corrosion between steel and copper. The crystals on the ZQ coating are honeycomb shaped calcite, which transform to C-CaCO3 with shorter whisker length about 10 μm as the contacting area of steel/copper galvanic couple increases. The C-CaCO3 reduces the adhesive area of crystals on the surface of self-cleaning coatings with low surface energy, making it easier to be removed in dynamic scaling environment. Therefore, a self-cleaning coating on copper for inhibiting CaCO3 crystallization and scaling was prepared, hoping to provide a new method for the crystallization of multiple ions on the surface of self-cleaning coatings in the field of engineering scale prevention.

The Efficiency of Calcium Oxide on Microbial Self-Healing Activity in Alkali-Activated Slag (AAS)

Alkali-activated slag (AAS) materials are one of the most promising sustainable construction composites. These novel materials are highly characterized by their improved mechanical and durability properties. Nevertheless, the high shrinkage rate hinders their full-scale applications. The low Ca/Si ratio, complex hydration process, and fine pore microstructure are the main causes of the reported shrinkage behavior. This study introduces Bacillus subtilis culture for healing the cracking behavior. The enzymatic action leads to precipitating calcium carbonate crystals that fill AAS cracks and pores. Incorporating calcium oxide has been recommended in multiple studies. The main purpose of adding calcium oxide is to enhance the engineering properties of AAS and provide more calcium ions for the biochemical reactions induced by the added bacteria. However, inconsistent findings about the influence of calcium oxide have been reported. This research provides further insights into the effect of calcium oxide (CaO) on the performance of microbial self-healing efficiency in AAS composite. The results highlight that incorporating calcium oxide as 7% of the binder partial replacement has an impact on the engineering properties of bio-AAS materials. The study recommends correlating the percentage of free calcium ions within the AAS mixture with the microbial activity.

Ion-doped γ-C2S: Clinker characteristics, carbonation products, and carbonation properties

The γ-crystalline form of dicalcium silicate (γ-C2S) is recognized for its carbonation activity, making it a promising low-carbon binder. This study investigates how impurity ions such as sodium, magnesium, phosphorus, potassium, titanium, nickel, copper, and zinc influence the carbonation characteristics of γ-C2S. Results on the calcined γ-C2S powders indicate that Na, P and K doping hinder the β-γ phase transition. Mg, Ti, Ni and Cu doping have little effect on the crystal form of γ-C2S, but substantially alter their morphology, evident in reduced particle size and increased surface folds. This increases the specific surface area and may facilitate the carbonation reaction. Analysis on carbonation products reveals calcium carbonate content is increasing especially in calcite crystals. The results of carbonation exothermic show the elevation of maximum temperature with the doping level increases. This may be attributable to ion doping promoting the dissociation of Ca2+. The increase in degree of carbonation and compressive strength illustrates the beneficial effects of these ionic doping on mechanical and carbonation properties, in particular, Ti ion doping increased 15.6 % and 75.7 % compared to the blank group, respectively. However, Zn doping is contrary to the results of other four ions and its addition has a negative effect on the properties of γ-C2S. All five ions (Mg, Ti, Ni, Cu, Zn) can be effectively solidified into the calcium carbonate crystals of the carbonation product, which is an important guideline for the future resource utilization of waste and industrialized production. Ion doping provides a reliable reference for future modification of γ-C2S.

Application of fluidized-bed homogeneous crystallization technology to carbon sequestration and recovery from flue gas

The Earth’s energy balance produced by human activity is the main factor in the complex relationship between greenhouse gases and global warming. The Taiwan Environmental Protection Agency reports that carbon dioxide makes up more than 95% of Taiwan’s most recent greenhouse gas emissions. This study used fluidized-bed homogeneous crystallization (FBHC) technology to recover carbonate in a simulated CO2-enriched flue gas. It was specifically designed to determine how carbonate removal and crystallization efficiency were affected by carbonate surface loading, the influence of the source of calcium ions, and interfering substances. Results revealed that the best surface loading at 55 kg m− 2 h− 1 achieved 93% removal and 84% crystallization efficiency. At 50 mg L− 1 of sulfate ions, the presence of more interfering compounds tends to reduce carbonate removal to 97% and 91% crystallization. Regarding X-ray diffraction data, the recovered carbonate crystals resembled calcium carbonate crystals. It has been demonstrated that carbonate can be recovered using FBHC technology as a method of CO2 capture and storage.

Diversification of von Willebrand Factor A and Chitin-Binding Domains in Pif/BMSPs Among Mollusks

Pif is a shell matrix protein (SMP) identified in the nacreous layer of Pinctada fucata (Pfu) comprised two proteins, Pif97 and Pif 80. Pif97 contains a von Willebrand factor A (VWA) and chitin-binding domains, whereas Pif80 can bind calcium carbonate crystals. The VWA domain is conserved in the SMPs of various mollusk species; however, their phylogenetic relationship remains obscure. Furthermore, although the VWA domain participates in protein–protein interactions, its role in shell formation has not been established. Accordingly, in the current study, we investigate the phylogenetic relationship between PfuPif and other VWA domain-containing proteins in major mollusk species. The shell-related proteins containing VWA domains formed a large clade (the Pif/BMSP family) and were classified into eight subfamilies with unique sequential features, expression patterns, and taxa diversity. Furthermore, a pull-down assay using recombinant proteins containing the VWA domain of PfuPif 97 revealed that the VWA domain interacts with five nacreous layer-related SMPs of P. fucata, including Pif 80 and nacrein. Collectively, these results suggest that the VWA domain is important in the formation of organic complexes and participates in shell mineralisation.

An adjustable bio-sealing method for rock fracture leakage mitigation

This study proposed a repeated adjustable mixture injection strategy (RAM) based microbial induced carbonate precipitation (MICP) for efficient mitigation of rock fracture leakage. Granite fractures with small apertures were investigated, and bio-sealing experiments were conducted using five different cementation solution (CS) concentrations (0.25−2 M). The results showed that the RAM-based bio-sealing method can seal and bond the small aperture rock fractures with high efficiency and uniform precipitation by adjusting the CS concentration. The RAM-based bio-sealing mechanism is attributed to the following four stages: (1) fixation of bacterial flocs onto the fracture surfaces, (2) precipitation of CaCO3 onto the fracture surfaces, (3) growth of pre-precipitated CaCO3 and adhesion of new-suspended CaCO3, and (4) bridging and clogging processes. The optimal CS concentration of 1 M resulted in a fracture filling rate up to 85%, a transmissivity reduction of 4 orders of magnitude, and a shear strength ranging from 512 kPa to 688 kPa. The bio-sealing effect was found to be influenced by the CS concentration on bacterial attachment, calcium carbonate yield and calcium carbonate bulk density. The CS concentration of 1 M promoted bacterial attachment, and increased calcium carbonate yield as well as calcium carbonate bulk density, while concentrations above 1 M had the opposite effect. The bulk density of calcium carbonate played a crucial role in the sealing and bonding performance of bio-sealed fractures, particularly at comparable filling ratios and bridging areas. The bulk density was regulated by the size of calcium carbonate crystals and was determined by Ca2+ concentration in the CS. This study provides valuable insights into the RAM-based bio-sealing method, highlighting its potential for efficient rock fracture leakage mitigation through precise control of CS concentration and understanding the underlying mechanisms.

CO2 sequestration by wet carbonated magnesium slag with high-content aragonite whiskers for improving cement performance as underground filling material

Magnesium slag (MS) is an alkaline waste residue from magnesium smelting processes. This study aimed to utilize the magnesium oxide in MS and adopt MgCl2 as the calcium carbonate crystal modifier to prepare high length-to-diameter ratio aragonite whiskers via wet carbonation, which can achieve high-value recovery of MS while capturing CO2 and enhancing cement as underground filling material. The effects of MgCl2 concentration on the carbonation process, composition, microstructure, and morphology were systematically investigated. With increasing MgCl2 concentration, more aragonite was obtained, reaching 94.9 % at 0.5 M MgCl2. Notably, at 0.1 M MgCl2, high length-to-diameter ratio aragonite whiskers with 16 were achieved. Introducing 1 wt% MS carbonated at optimal 0.1 M MgCl2 into cement increased the 3 d and 28 d compressive strengths by 17.8 % and 22 %, respectively. Moreover, an excellent CO2 sequestration capacity of up to 20.33 g CO2 per 100 g MS was obtained for the carbonated MS. Therefore, wet carbonated MS with high content aragonite whiskers is a promising method for MS high-value utilization while reducing cement usage and CO2 emission, as well as improving cement performance as underground filling material.

Hollow fiber membrane governed microjet flow regime for confined crystallization of large‐sized crystal aggregates

AbstractConfined crystallization can realize controllable nucleation and growth of crystals with targeted morphologies in a restricted region. Here, we achieved confined reactive crystallization within a novel micro columnar jet flow regime constructed by the hollow fiber membrane. The interface of the jet flow corresponds as the restricted region for reactive crystallization, and the large‐sized calcium carbonate (CaCO3) crystals aggregates with millimeter length can ordered and self‐assembly grow along the boundary of this region. Formation mechanism of the jet flow was systematically investigated by real‐time observation and force analysis. The detected detachment‐regrowth cycle during the experiments furtherly uncovered the potential for continuous operation. Linear (diameter: 0.12–0.3 mm; length: 1.5–3.1 mm) and lamellar crystals (thickness of 200–300 nm and average area of 0.21 mm2) were obtained by effectively manipulating the diameter and effective length of jet flow.

Diagnostic Accuracy of Raman Spectroscopy Integrated With Polarized Light Microscopy for Calcium Pyrophosphate-Associated Arthritis.

We studied the performance of integrated Raman polarized light microscopy (iRPolM) for the identification of calcium pyrophosphate (CPP)-associated arthritis (CPPD). This is a diagnostic accuracy study including 400 consecutive synovial fluid samples from a single hospital in the Netherlands. Accuracy measures were calculated against polarized light microscopy (PLM) and the 2023 American College of Rheumatology (ACR)/EULAR criteria set for CPPD. The interrater reliability between iRPolM and the 2023 ACR/EULAR criteria set for CPPD was strong (κ = 0.88). The diagnostic performance of iRPolM compared to the 2023 ACR/EULAR criteria set was sensitivity 86.0% (95% confidence interval [CI] 73.3-94.2), specificity 99.1% (95% CI 97.5-99.8), positive likelihood ratio 100.33 (95% CI 32.3-311.3), negative likelihood ratio 0.14 (95% CI 0.07-0.28), positive predictive value 93.5% (95% CI 82.2-97.8), negative predictive value 98.0% (95% CI 82.2-97.8), and accuracy 97.5% (95% CI 95.5-98.8). We allowed rheumatologists to rate the certainty of their microscopic identification of CPP and found a large correspondence between iRPolM and a certain identification (κ = 0.87), whereas only 10% of the uncertain CPP identifications could be confirmed with iRPolM. We identified several novel particle types in synovial fluid analysis, including calcium carbonate crystals, deposited carotenoids, microplastics, and three types of Maltese cross birefringent objects. iRPolM can easily identify CPP crystals with a strong diagnostic performance. PLM alone is not specific enough to reliably resolve complicated cases, and the implementation of Raman spectroscopy in rheumatology practice can be of benefit to patients with suspected CPPD.

Влияние факторов водной среды на минерализацию цианобактерий и зеленых водорослей (Республика Коми)

This article describes crystallization formed in the exogenous mucous sheath of phototrophic microorganisms living in the surface waters of the south area of the Komi Republic. The mineralization of colonies of cyanobacteria of the Gloeotrichia sp. and green algae Chaetophora elegans was studied. The waters of rivers in the Northern Dvina basin have been studied as habitats for the microorganisms. They have a different composition: HCO3 Ca–Mg, typical for the taiga zone of a temperate continental climate; SO4–HCO3 Ca–Mg and Cl–Na (in the zone of technogenic pollution). Using the example of these neutral — weakly alkaline ultrafresh — salty (0.2—2.8 g/L) waters, it is shown that the geochemistry of the aquatic environment is one of the most important factors influencing the minerogenesis. Calcite, vaterite, quartz and halite were identified in dried colonies of microorganisms within the extracellular polymeric substance using the methods of X-ray diffractometry, electron microscopy, microprobe analysis and IR spectroscopy. The morphological features of microminerals are presented depending on the type of microorganisms. Calcium carbonate crystals and aggregates are formed within the exogenous mucous sheath of algae and cyanophytes. The carbon isotope composition of carbonates (13C –7.5 and –3.8 ‰ PDB) indicates their organic nature. The formation of minerals, morphological features of crystals and the degree of biomineralisation of colonies of phototrophic microorganisms are conditioned by the physicochemical parameters of the aquatic environment. The possibilities of chemogenic precipitation of carbonates from the studied natural waters were assessed.

Study on the Mechanism of Wellbore Blockage and Scaling Trend Prediction of Keshen Block

Located in the Kuqa foreland basin, Tarim Basin, the Xinkeshen gas field is a rare ultra-deep and ultra-high-pressure fractured tight sandstone gas reservoir. During the development process, the fluid in the well migrates from the bottom hole to the ground. Due to the huge temperature drop and pressure drop in the wellbore, salting-out and scale-out occur in the well to destroy the oil and gas flow channel, resulting in a decrease in gas production in the well and seriously affecting the normal production of the oil field. Aiming at the problem of wellbore scaling and blockage in the Keshen gas field, this paper takes the wellbore of the Keshen block as the research object. After analyzing the composition of produced water and scale in the wellbore, the solution of ‘fixing scale, clarifying mechanism, early prediction, and fine treatment’ is formulated, and the analysis and evaluation technology of the scale formation process and the prediction model of the gas well model are formed. The wellbore blockage in Keshen block is composed of iron oxide, calcium carbonate crystal, calcite crystal, and wellbore steel falling off due to electrochemical corrosion. It is indicated that the scale attached to the steel sheet causes electrochemical corrosion of the steel sheet, resulting in ‘hydrogen embrittlement’, resulting in the bubbling and falling off of the wellbore steel. Through simulation, it is found that the amount of fouling increases with the increase in wellbore depth, and the amount of fouling is 1.97 kg/d at 6800 m, which is in good agreement with the actual situation. Based on the temperature and pressure curves in the wellbore, the simulation results show that the corrosion rate reaches the highest value of 6.37 mm/yr at the depth of 3400 m. Because of the above problems, a polyaspartic acid scale inhibitor with a scale inhibition rate of 98.9% for wells in Keshen block was synthesized. It has important guidance and reference significance for the accurate treatment of scaling problems in the Keshen gas well.

Preparation and scale inhibition performance of modified polyaspartic acid (M-PASP)

Modified polyaspartic acid (M-PASP) was synthesized by modifying ammonia- polysuccinimide (ammonia-PSI) through a ring-opening reaction using a modifier derived from ethylenediamine, maleic anhydride, and NaOH. In addition to M-PASP, conventional polyaspartic acid (PASP) was also synthesized for comparison. The structure of conventional PASP and M-PASP were characterized by FT-IR and 1H NMR. The influence of raw materials ratio, reaction temperature and reaction time on the intrinsic viscosity of M-PASP were investigated in detail. The static scale inhibition method was used to evaluate the scale inhibition performance. The results showed that M-PASP exhibited significantly superior scale inhibition performance against CaCO3 compared to conventional PASP. Additionally, it was observed that the scale inhibition rate of M-PASP on CaCO3 increased with increasing intrinsic viscosity. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to examine the surface morphology and structure of CaCO3 crystals, respectively. The results revealed that the addition of M-PASP led to a reduction in the grain size of CaCO3 crystals and disruption of their surface morphology. In addition, molecular dynamics (MD) simulation was utilized to analyze the interaction mechanism between the polymers and calcium carbonate crystals. Based on the findings, it was postulated that the scale inhibition mechanism of M-PASP against CaCO3 involves a comprehensive interplay of several factors, including chelation solubilization, dispersion aggregation and lattice distortion.

Crystal sediment profile in the urine of public transportation drivers on route 2 in Kupang city

Background: Drivers have a profession that requires prolonged sitting, leading to the release of bone calcium into the bloodstream, which can trigger the formation of urinary stones or nephrolithiasis. Urinary stone (nephrolithiasis) is a condition where stones form in the urinary tract. Objectives: The aim of this study was to describe the crystal sediment profile in the urine of public transportation drivers on Route 2 in Kupang City. Materials and Methods: This descriptive study involved 16 public transportation drivers on Route 2 in Kupang City as research subjects. Data were collected through interviews. Results: The results showed the presence of various crystals in the urine sediment, including Calcium Oxalate crystals (25%), Calcium Carbonate crystals (18.75%), Uric Acid crystals (12.5%), and Amorphous crystals (6.25%). Conclusions: Based on the characteristics and habits of the respondents, it was found that frequent urinary retention, drinking less than 1 liter of water per day, and consuming supplemented or carbonated drinks were the three main factors affecting urine sedimentation in public transportation drivers on Route 2 in Kupang City.

Carbonation curing of belite-rich cement: The role of fly ash and strengthening mechanism

Belite-rich cement (BRC) has gained increased attention in recent years due to its low energy consumption and high long-term performance. However, the carbonation behavior of the binder formed by its combination with fly ash (FA) has been scarcely revealed. This study investigated the influence of carbonation curing and FA replacement level on the carbon capture and mechanical properties of BRC. The carbon uptake, phase composition, microstructure, and micromorphology of BRC-FA composites after carbonation curing were characterized through quantitative XRD, TG, FT-IR, MIP, and SEM-EDS. The results indicated that carbonation curing significantly increased the compressive strength by up to 81.6% of BRC compared to standard curing due to the high reactivity of belite phase with CO2, whilst the hydration products of BRC gradually disappeared, and calcite and amorphous silica became the main phase accompanied with pore refinement behavior. Moderate addition of FA increased the degree of carbonation and compressive strength of BRC-FA composites, however excessive addition (45%) of FA results in adverse effect. Additionally, FA accelerated the phase recombination but coarsened the pore structure. The rapidly formed calcium carbonate crystals stacked and squeezed together, its blend with amorphous silica gel, and the pore structure rapidly densified explain the carbonation strength growth of BRC-FA composites.

Study on Reducing Water Absorption of Recycled Aggregates (RAs) by Microbial Mineralization.

Crushing waste concrete and using it directly as RAs has the disadvantages of high porosity and high water absorption. To achieve the reuse of resources, the researchers use microbial mineralization methods to further reinforce RAs. In this paper, the effect of the microbial carbonic anhydrase mineralization method on the water absorption of RAs was investigated, and the macroscopic analysis was performed by determining the indexes of water absorption and apparent density of RAs before and after the modification, and the microscopic analysis of RAs by using the methods of SEM, XRD, DSC, and EDS as well. According to the microscopic analysis, the mineralization products of microorganisms are calcium carbonate crystals, and with the increase in microbial liquid concentration, the water absorption rate of RAs shows a trend of decreasing and then increasing, and it can be found through the microscopic morphology that abundant mineralization products attached to the surface of the aggregate lead to the surface of the aggregate becoming rougher and more porous. The method of soaking the RAs in 3% bacterial solution and 0.1 mol/L calcium acetate solution followed by carbonation with 20% CO2 resulted in a 4.85% reduction in water absorption.

Structural and Compositional Changes in Two Marine Shell Traditional Chinese Medicines: A Comparative Analysis Pre- and Post-Calcination.

Arcae concha and Meretricis concha cyclinae concha are two marine shellfish herbs with similar composition and efficacy, which are usually calcined and used clinically. This study investigated variations in the inorganic and organic components of Arcae concha and Meretricis concha cyclinae concha from different production regions, both Arcae concha and Meretricis concha cyclinae concha. The aim was to enhance the understanding of these two types of marine shell traditional Chinese medicine (msTCM) and provide a foundation for their future development and application. Spectroscopic techniques, including infrared spectroscopy, X-ray spectroscopy, and X-ray fluorescence spectroscopy, were used to analyze the calcium carbonate (CaCO3) crystal and trace elements. Thermogravimetric analysis was used to investigate the decomposition process during heating. The proteins were quantified using the BCA protein assay kit. Principal component analysis (PCA) was used to classify inorganic elements in the two marine shellfish traditional Chinese medicines. No significant differences were found among the various production regions. The crystal structure of CaCO3 in the raw products was aragonite, but it transformed into calcite after calcination. The contents of Ca, Na, Sr, and other inorganic elements were highest. The protein content was significantly reduced after calcination. Therefore, these factors cannot accurately reflect the internal quality of TCM, rendering qualitative identification challenging. CaCO3 dissolution in the decoction of Arcae concha and Meretricis concha cyclinae concha increased after calcination, aligning with the clinical application of calcined shell TCM. PCA revealed the inorganic elements in them, indicating that the variation in trace element composition among different drugs leads to differences in their therapeutic focus, which should be considered during usage. This study clarifies the composition and structure changes of corrugated and clam shell before and after calcining, and it lays the foundation for the comprehensive utilization of marine traditional Chinese medicine. These technical representations reveal the differences between raw materials and processed products, which will provide support for the quality control of other shellfish TCM.

The First High-Quality Genome Assembly of Freshwater Pearl Mussel Sinohyriopsis cumingii: New Insights into Pearl Biomineralization.

China leads the world in freshwater pearl production, an industry in which the triangle sail mussel (Sinohyriopsis cumingii) plays a pivotal role. In this paper, we report a high-quality chromosome-level genome assembly of S. cumingii with a size of 2.90 Gb-the largest yet reported among bivalves-and 89.92% anchorage onto 19 linkage groups. The assembled genome has 37,696 protein-coding genes and 50.86% repeat elements. A comparative genomic analysis revealed expansions of 752 gene families, mostly associated with biomineralization, and 237 genes under strong positive selection. Notably, the fibrillin gene family exhibited gene family expansion and positive selection simultaneously, and it also exhibited multiple high expressions after mantle implantation by transcriptome analysis. Furthermore, RNA silencing and an in vitro calcium carbonate crystallization assay highlighted the pivotal role played by one fibrillin gene in calcium carbonate deposition and aragonite transformation. This study provides a valuable genomic resource and offers new insights into the mechanism of pearl biomineralization.

A new bioslurry-induced restoration method via biomineralization for fragmented ceramic cultural relics

This study presents a new restoration method for fragmented ceramic cultural relics using bioslurry-induced biocementation via a microbially induced calcium carbonate precipitation (MICP) process. Bioslurry is highly urease active calcium carbonate crystals, which serve as filling and cementitious material with newly induced calcite precipitation when supplying cementation solution (urea and calcium source). With the pre-filling of bioslurry and newly induced calcite crystals, the fragmented ceramic can be connected and the gap along the fracture surface can be sealed. Due to the high urease active bacteria cells embedded in bioslurry, the ceramic restoration can be completed in 24 h with the optimal concentration of cementation solution of 1.6 M. Taking the advantage of bonding effect gained from newly induced calcite precipitation, the tensile strength was improved up to 0.92 MPa through a customized tensile strength test. This is satisfactory to ensure the stability and integrity of fragmented ceramic after bioslurry-induced restoration. A demonstrative restoration has been completed on fragmented ceramics from Ming Dynasty. With the good bonding strength and high stability of bioslurry-induced calcite precipitation, the proposed bioslurry-induced restoration method contributes valuable insights to the conservation of ceramic cultural relics. Other prospective applications include the restoration of masonry relics and bone relics.