Inorganic Mineral Component Research Articles

One-Pot Synthesis of Biochar from Industrial Alkali Lignin with Superior Pb(II) Immobilization Capability.

This study synthesized biochar through a one-pot pyrolysis process using IALG as the raw material. The physicochemical properties of the resulting biochar (IALG-BC) were characterized and compared with those of biochar derived from acid-treated lignin with the ash component removed (A-IALG-BC). This study further investigated the adsorption performances and mechanisms of these two lignin-based biochars for Pb(II). The results revealed that the high ash content in IALG, primarily composed of Na, acts as an effective catalyst during pyrolysis, reducing the activation energy and promoting the development of the pore structure in the resulting biochar (IALG-BC). Moreover, after pyrolysis, Na-related minerals transformed into particulate matter sized between 80 and 150 nm, which served as active adsorption sites for the efficient immobilization of Pb(II). Adsorption results demonstrated that IALG-BC exhibited a significantly superior adsorption performance for Pb(II) compared to that of A-IALG-BC. The theoretical maximum adsorption capacity of IALG-BC for Pb(II), derived from the Langmuir model, was determined to be 809.09 mg/g, approximately 40 times that of A-IALG-BC. Additionally, the adsorption equilibrium for Pb(II) with IALG-BC was reached within approximately 0.5 h, whereas A-IALG-BC required more than 2 h. These findings demonstrate that the presence of inorganic mineral components in IALG plays a crucial role in its resource utilization.

Mechanism of targeted adsorption and specific action of bone char on ionic organic pollutants: An analysis based on differences in physicochemical properties

Adsorption is a widely recognized and effective method for treating high-concentration organic industrial wastewater. Bone char (BC) is a promising adsorbent for removing ionic organic pollutants (IOPs) from printing and dyeing wastewater due to its advantageous adsorption properties. To analyze BC's targeted adsorption and specific action mechanism on IOPs, the author first elucidated the physicochemical properties of BC under different preparation conditions. Subsequently, the study compared the targeted adsorption efficacy of BC on various types and molecular structures of IOPs. Through correlation analysis, feature importance analysis, and consideration of the properties of the target substance, the study investigated the targeted adsorption laws of BC for IOPs. Lastly, for substances with specific adsorption characteristics, range analysis, structure–activity relationship analysis, and quantitative analysis of adsorption mechanisms were employed to elucidate the action mechanism of BC. The results indicate that the differences in physicochemical properties (especially CEC and pH) caused by the inorganic mineral components of BC and the number of conjugated double bonds in the molecular structure of IOPs are key factors determining the adsorption effect. Controlling BC's pore structure and electrical conductivity based on the aggregates' conjugated double bonds and particle size can improve adsorption outcomes. The hierarchy of preparation factors influencing the adsorption performance of BC is pyrolysis temperature > particle size > pyrolysis atmosphere. The adsorption of malachite green (MG) by BC primarily involves chemical reactions, including mineral complexation effect (52.38 %), electrostatic interaction (24.76 %), π-π interaction (8.15 %), metal ion exchange (8.12 %), and physical pore filling (6.59 %). It is speculated that the primary interaction mechanism between BC and MG is through cation-π bonds formed between metal cations dissociated from the inorganic mineral components of BC and MG, facilitated by strong electrostatic interaction. The findings offer a theoretical basis for the practical utilization of BC in adsorbing IOPs.

Study on improving the crack self-healing width and depth based on microbial mineralization modified by Ca–Al bimetallic hydroxides

In-depth research was conducted on the application of an inorganic mineral composite microbiological remediation agent in mortar specimens with varying crack widths. Firstly, the remediation agent's efficacy in repairing cracks was validated through surface observations and macroscopic performance tests, including methods such as crack surface image capture, crack water permeability recovery rate testing, and crack ultrasonic velocity recovery testing. Subsequently, this study investigated whether the inorganic mineral and microbiological components in the remediation agent played a role by examining the repair products within the cracks. Material composition was identified using techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR). The primary minerals identified were layered double hydroxides and calcium carbonate. Furthermore, it was found that CI− and SO42− ions were immobilized within the interlayers of layered double hydroxides, aligning with the expected objectives of the experiment, thus confirming the feasibility of this study. Finally, the self-healing mechanism of cracks in this experiment was elucidated through a schematic diagram, demonstrating that the use of layered double hydroxides as inorganic minerals improved the microenvironment of the crack area, lowered the pH in the crack region, providing a favorable environment for microbial growth and mineralization. Additionally, these minerals could adsorb erosive ions such as CI− and SO42−, thereby enhancing the durability of cement-based materials.

Physicochemical properties of charcoal aerosols derived from biomass pyrolysis affect their ice-nucleating abilities at cirrus and mixed-phase cloud conditions

Abstract. Atmospheric aerosol particles play a key role in air pollution, health, and climate. Particles from biomass burning emissions are an important source of ambient aerosols, have increased over the past few decades, and are projected to further surge in the future as a result of climate and land use changes. Largely as a result of the variety of organic fuel materials and combustion types, particles emitted from biomass burning are often complex mixtures of inorganic and organic materials, with soot, ash, and charcoal having previously been identified as main particle types being emitted. Despite their importance for climate, their ice nucleation activities remain insufficiently understood, in particular for charcoal particles, whose ice nucleation activity has not been reported. Here, we present experiments of the ice nucleation activities of 400 nm size-selected charcoal particles, derived from the pyrolysis of two different biomass fuels, namely a grass charcoal and a wood charcoal. We find that the pyrolysis-derived charcoal types investigated do not contribute to ice formation via immersion freezing in mixed-phase cloud conditions. However, our results reveal considerable heterogeneous ice nucleation activity of both charcoal types at cirrus temperatures. An inspection of the ice nucleation results together with dynamic vapor sorption measurements indicates that cirrus ice formation proceeds via pore condensation and freezing. We find wood charcoal to be more ice-active than grass charcoal at cirrus temperatures. We attribute this to the enhanced porosity and water uptake capacity of the wood compared to the grass charcoal. In support of the results, we found a positive correlation of the ice nucleation activity of the wood charcoal particles and their chemical composition, specifically the presence of (inorganic) mineral components, based on single-particle mass spectrometry measurements. Even though correlational in nature, our results corroborate recent findings that ice-active minerals could largely govern the aerosol–cloud interactions of particles emitted from biomass burning emissions.

Chimeric protein-mediated dual mineral formation on biopolymer: Non-segregated and well-distributed deposition of CaCO3 and silica particles

Incorporation of biogenic or biocompatible synthetic polymers with inorganic mineral components have been suggested for the preparation of more bioactive materials. However, when two different inorganic minerals such as Ca- and Si-based minerals are introduced onto organic polymers, each mineral is deposited in a segregated form. Here, we presented a biomolecule-mediated preparation method for dual mineral-deposited polymer, in which two inorganic minerals were well-deposited on organic polymer with the aid of biological molecules. A chimeric bio-macromolecules, a fusion protein (CA-SFP) of carbonic anhydrase (CA) and silica-forming peptide (SFP), was designed and used. Surface-immobilized CA-SFP enabled the deposition of CaCO3 and silica nanoparticles on biopolymer without any segregated aggregation. SEM, EDS, FTIR, and swelling ratio analysis indicated that in the developed dual mineral-deposited polymer, each mineral was well-distributed across the polymer surfaces. Investigation by MTS assays, fluorescent imaging, and RT-qPCR revealed that the dual mineral-deposited polymer, when used as bone scaffolds, led to better cell proliferation and differentiation without any significant cytotoxicity compared to the counterparts. These results show that our mineral-deposition method mediated by biomolecules not only overcomes mineral-segregation involving multi-mineral formations, but also facilitates the preparation of highly-bioactive composite materials.

Experimental and Numerical Simulation of Water Adsorption and Diffusion in Coals with Inorganic Minerals

The study on the adsorption and micropore filling of water vapor in coal is significant for predicting coalbed methane content in coal seams. The primary purpose of this study is to explain the effects of coal pore structure and its surface chemistry on water vapor monolayer adsorption, micropore filling, and diffusion coefficient. First, X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP) analyzed inorganic mineral components of two kinds of coal samples and pore fissures structures. Then, we divide pores and fissures according to the theory of fractal dimensions. Furthermore, we carried out the water vapor adsorption and desorption experiments on two kinds of coal; in particular, we set 14 points of relative pressure between 0 and 0.2. Guggenheim–Anderson–de Boer (GAB), Frenkel–Halsey–Hill (FHH), and Freundlich models were used to analyze the data of water vapor adsorption to obtain the boundary pressure points of the monolayer, multilayer adsorption, and capillary condensation. Finally, the parameters of the models were obtained by fitting the adsorption data of water vapor according to the combined GAB, Freundlich, DA, and bidisperse adsorption (BDA) models to analyze the interaction mechanism between coal and water. We explain why the strongly adsorbed water minerals, such as pyrite, illite, and nacrite coal, can improve water vapor’s adsorption and diffusion capacity in coal pore fissures.

Effect of Coal Gasification Slag on Improving Physical Properties of Acid Soil

Coal gasification slag (CGS) is a coal-based solid waste formed by the transformation of inorganic mineral components and carbon components in raw coal into slag during coal gasification. To explore its influence on the physical characteristics of acid soil and study the influence mechanism on the water holding capacity of acid soil, the coarse and fine CGS were used as materials to mix with acid soil in different proportions. The volume weight, particle size composition, and water retention performance of the mixed soil were tested, and the changes of soil water characteristic curve were analysed. The results showed that, after mixing the acid soil with CGS, the particle size composition of acid soil was significantly improved, the sand content increased by 13.27–195.46%, the clay and silt content decreased by −2.14–38.62% and 3.22–40.06%, respectively; and the soil bulk density decreased significantly (P < 0.05), with a decrease range of 3.38–28.12%. The soil texture also changed from silty loam to sandy loam, and the water retention performance showed an upward trend, which significantly affected the soil saturated water content, capillary water capacity and field water capacity, with an increase range of 2.87–38.09%, 1.73–27.92% and 4.18–22.27%, respectively. The Van Genuchten (VG) model could fit the soil water characteristic curve well, indicating that the water retention of acid soil was significantly improved by adding CGS. In conclusion, CGS could improve the water physical properties effectively, and improve the water retention and water holding properties of acid soil significantly. This feature is conducive to the environmentally friendly utilization of CGS to improve agricultural acid soil.

Loaded n-Hydroxyapatite/SSG 3D Scaffolds as a Drug Delivery System of Nigella sativa Fractions for the Management of Local Antibacterial Infections.

As a result of their close similarities to the inorganic mineral components of human bone, hydroxyapatite nanoparticles (n-HAp) are widely used in biomedical applications and for the elaboration of biocompatible scaffold drug delivery systems for bone tissue engineering. In this context, a new efficient and economic procedure was used for the consolidation of n-HAp in the presence of various Nigella sativa (NS) fractions at a near-room temperature. The research conducted in the present study focuses on the physicochemical properties of loaded n-HAp 3D scaffolds by NS fractions and the in vitro antibacterial activity against Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 27853), and Gram-positive (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 700603) bacteria. In order to better understand the effect of the inserted fractions on the HAp molecular structure, the elaborated samples were subject to Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopic analyses. In addition, the morphological investigation by scanning electron microscope (SEM) of the loaded n-HAp 3D scaffolds demonstrated the presence of a porous structure, which is generally required in stimulating bone regeneration. Furthermore, the fabricated 3D composites exhibited significant antibacterial activity against all tested bacteria. Indeed, MIC values ranging from 5 mg/mL to 20 mg/mL were found for the HAp-Ethanol fraction (HAp-Et) and HAp-Hexane fraction (HAp-Hex), while the HAp-Aqueous fraction (HAp-Aq) and HAp-Methanol fraction (HAp-Me) showed values between 20 mg/mL and 30 mg/mL on the different strains. These results suggest that the HAp-NS scaffolds were effective as a drug delivery system and have very promising applications in bone tissue engineering.

Particulate matter emission during municipal solid waste combustion: Submicron particulates formation mechanism

This paper presents an information on size distribution, inorganic composition and formation mechanism of submicron particles generated from MSW combustion. The XRD and CCSEM analysis results clearly showed that NaCl, KCl, K3Na(SO4)2, and SiO2 are the major inorganic mineral components in submicron particles. Submicron particles are mainly composed of organic components, alkali chlorides, alkali sulfates, and refractory inorganic minerals, but they account for different proportions in PM0.2 and PM0.2-1. There are five formation modes of submicron particles in MSW combustion: “condensation”, “nucleation”, “accumulation”, “crystallization” and “fragmentation”. The “condensation” mechanism mainly seen in PM0.2 composed of gas components, the “crystallization” and “fragmentation” modes formed by alkali salts and char particles are mainly present in PM0.2-1, the “nucleation” and “accumulation” modes coexist in PM0.2 and PM0.2-1. As the combustion temperature increased, the alkali chlorides and sulfates in the “crystallization” form decreased, and the inorganic mineral components in the “nucleation” form increased, which results in the variation of size distribution of submicron particles. In addition, volatile alkali salt nucleation experiments show that when alkali chloride and sulfate coexist in high-temperature flue gas, heterogeneous nucleation and agglomeration can significantly enhance the accumulation of particles in the range of 0.2–0.5 μm.

Synthesis and Characterization of Hydroxyapatite from Duck Eggshell by Wet Precipitation Process

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is the most stable form of calcium phosphate and widely used in various medical applications, mainly in orthopedics and dentistry due to its close similarities with the inorganic mineral component of bone and teeth. This study aims to synthesize hydroxyapatite from duck eggshell using the precipitation method. The duck eggshell was calcined, hydrated (slaking) and underwent carbonation to form Precipitated Calcium Carbonate (PCC). Afterwards, (NH4)2HPO4 was added to produce HAp by varying the molar ratio of Ca/P by 1.67, 1.77 and 1.87 and stirring speed by 200, 250, 300rpm under basic condition (pH 10 – 11). The best results were obtained at a molar ratio of 1.77 with 200rpm stirring speed. Furthermore, the X-ray Diffraction (XRD) analysis showed that its crystals were hexagonal with sizes of 23.062nm, in the absence of other crystalline phases. Therefore, the hydroxyapatite was obtained in the agglomerates form with a specific surface area of ??55.929m2/g.

Effect of organic minerals and alpha-ketoglutarate in pheasant diet on performance, hatchability and the composition of eggs

This study determined the effect of supplementation of the pheasant diet with mineral components (Ca, Fe, Zn and Cu) from organic sources with or without the addition of alpha-ketoglutarate (AKG) on productivity, hatchability parameters, nutrients and mineral content in pheasant eggs. Studies were performed on three groups of laying pheasants, which were kept in aviaries and received a standard mixture (Group I, the control group), a mixture with Ca, Fe, Zn, and Cu glycinates which replaced 50% of the mineral components in inorganic form (Group II), or a mixture with chelates and a 200 mg alpha-ketoglutarate supplement (Group III). Supplementation of the diet with chelates raised the content level of the mineral components in the whole egg and yolk, mainly the contents of calcium, zinc and iron. The addition of 200 mg of alpha-ketoglutarate to the diet with calcium, zinc, iron and copper chelates of glycine (50% of the supplemented elements) resulted in improved laying capacity and rates of reproduction and rearing of chicks, with a slight decrease in the size and weight of eggs. The eggshell was thinner, and the albumen and the Haugh Unit score were higher. Inorganic mineral components can be replaced by glycine chelates at up to 50%, especially with the addition of 200 mg of AKG, in the pheasant diet in commercial breeding.

Characterisation of Atmospheric Particulate Matter from Opencast Coal Mining Activities and Adjacent Communities

Standard source apportionment techniques for atmospheric particulate (PM) collected near opencast coal mines provide less accurate results, as the inorganic mineral components in the overburden and at adjacent residential locations are similar. This study explores the use of the stable carbon (C) and nitrogen (N) isotope ratios (13C/12C and 15N/14N) and thermal optical methods to differentiate sources of carbonaceous material in the atmospheric PM samples from the opencast coal mines and adjacent communities. Both techniques allow a clear distinction between atmospheric PM samples from the opencast coal mines and communities to be made, although distinguishing between the contributions of coal combustion, liquid fuel combustion and the domestic use of biomass for requires further analysis.

MgCl2 promotes mouse mesenchymal stem cell osteogenic differentiation by activating the p38/Osx/Runx2 signaling pathway.

Magnesium, an important inorganic mineral component in bones, enhances osteoblast adhesion and osteogenic gene expression. Mg2+-containing hydroxyapatite promotes mouse mesenchymal stem cell (MMSC) osteogenic differentiation. In the present study, MMSCs were cultured in media containing different concentrations of MgCl2 (0 and 20 mM) for different time periods. Western blotting and reverse transcription-quantitative PCR were performed to determine the expression levels of phosphorylated (p)-p38 mitogen-activated protein kinase (MAPK), the osteoblast-specific transcription factor Osterix (Osx), runt-related transcription factor 2 (Runx2), and p38 downstream genes, such as 27 kDa heat shock protein (hsp27), activating transcription factor 4 (Atf4), myocyte enhancer factor 2C (Mef2c) and CCAAT/enhancer-binding protein homologous protein (Ddit3). The facilitatory effect of MgCl2 on MMSC osteogenic differentiation was assessed via Alizarin Red staining. The results suggested that MgCl2 increased p38 phosphorylation compared with the control group. Downstream genes of the p38 signaling pathway, including Osx and Runx2, as well as several osteogenesis-associated downstream target genes, including Hsp27, Atf4, Ddit3 and Mef2c, were significantly upregulated in the Mg2+-treated group compared with the control group. The increased osteogenic differentiation in the Mg2+-treated group was significantly attenuated in MMSCs treated with SB203580, a specific inhibitor of the p38 signaling pathway. The results suggested that appropriate concentrations of MgCl2 promoted MMSC osteogenic differentiation via regulation of the p38/Osx/Runx2 signaling pathway.

The effect of carbon nanotubes on osteogenic functions of adipose-derived mesenchymal stem cells in vitro and bone formation in vivo compared with that of nano-hydroxyapatite and the possible mechanism

It has been well recognized that the development and use of artificial materials with high osteogenic ability is one of the most promising means to replace bone grafting that has exhibited various negative effects. The biomimetic features and unique physiochemical properties of nanomaterials play important roles in stimulating cellular functions and guiding tissue regeneration. But efficacy degree of some nanomaterials to promote specific tissue formation is still not clear. We hereby comparatively studied the osteogenic ability of our treated multi-walled carbon nanotubes (MCNTs) and the main inorganic mineral component of natural bone, nano-hydroxyapatite (nHA) in the same system, and tried to tell the related mechanism. In vitro culture of human adipose-derived mesenchymal stem cells (HASCs) on the MCNTs and nHA demonstrated that although there was no significant difference in the cell adhesion amount between on the MCNTs and nHA, the cell attachment strength and proliferation on the MCNTs were better. Most importantly, the MCNTs could induce osteogenic differentiation of the HASCs better than the nHA, the possible mechanism of which was found to be that the MCNTs could activate Notch involved signaling pathways by concentrating more proteins, including specific bone-inducing ones. Moreover, the MCNTs could induce ectopic bone formation in vivo while the nHA could not, which might be because MCNTs could stimulate inducible cells in tissues to form inductive bone better than nHA by concentrating more proteins including specific bone-inducing ones secreted from M2 macrophages. Therefore, MCNTs might be more effective materials for accelerating bone formation even than nHA.

Synthesis of hydroxyapatite by hydrothermal and microwave irradiation methods from biogenic calcium source varying pH and synthesis time

Hydroxyapatite is the main bones and teeth inorganic mineral component. This material has been an object of research aiming its use in biomaterials as bone replacement option for biomedical applications. In this investigation, the synthesis of hydroxyapatite was studied by the Hydrothermal (HT) and Microwave Irradiation (MW) methods. Here, parameters such as pH (9 and 11) and synthesis time were varied, and residue of chicken eggshell was used as calcium precursor. The obtained powders were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Dispersive Energy X-ray Spectroscopy (EDS), and Transmission Electron Microscopy (TEM). The results showed that the material synthesized when the pH reached the value of 9 which generated less carbonated powders than those with pH of 11. The Hydrothermal method presented more satisfactory morphological results according to the TEM analysis. This procedure was considered more suitable as a route to obtain hydroxyapatite as biomaterial.

Characterization of Cu distribution in clay-sized soil aggregates by NanoSIMS and micro-XRF

Aggregates are the basic structural units of soils. Fine soil aggregates are crucial pools for the retention of heavy metals. In this study, we evaluated the accumulation characteristics of exogenous Cu in the <2 μm aggregate fractions from a Histosol for an aging of 28 months by nano-scale secondary ion mass spectrometry (NanoSIMS) and synchrotron micro-X-ray fluorescence (micro-XRF). Results showed that the correlations between Cu and Fe/Al/Mn increased from 0.10–0.17 to 0.55–0.63, while those between Cu and C decreased sharply from 0.61 to 0.10 and then increased to 0.36, indicating that exogenous Cu tended to accumulate on inorganic mineral components. The carbon NEXAFS data suggested that the relative content of aromatic and carboxyl carbon decreased from 8.1% and 30.8% to 3.6% and 17.8% at month 12, and increased to 5.9% and 26.0% at month 28, respectively. However, an opposite trend was found for alkyl and carbonyl carbon which showed an increase at month 12 followed by a decrease afterwards. The consistency for the correlations between Cu and C with the changes of aromatic and carboxyl carbon indicated their key roles in the binding of Cu on the organic components in the <2 μm aggregates of Histosol. These direct observations offer a better understanding on the interactions of heavy metals with various soil components which is critical for the risk assessment and fate evaluation of exogenous Cu in soil ecosystems.

Numerical study on flow dynamics characteristics of supercritical water transporting particles under transcritical temperature conditions driven by pressure difference

Supercritical water gasification (SCWG) is famous for achieving complete conversion of raw organic matter with the temperature below its ash melting point. Inorganic mineral components associated with raw organic matter will form solid slag particles after the reaction of SCWG is completed. Discharge of the slag particles from reactor is a supercritical water (SCW) transporting particles process under transcritical temperature conditions driven by pressure difference. A comprehensive three-dimensional two-fluid model (TFM) is firstly developed in this study to research the flow dynamics characteristics during the particle transport process. The effect of transport pressure difference (ΔP) and particle outlet position (ΔH) on particle transport are investigated. Results show that the particles can be transported out the reactor smoothly under the action of ΔP, and the solid-containing ratio, sr, can reach to 78.27% with ΔP of 5 MPa and ΔH of 55 mm. Large ΔP can enhance particle transport efficiency, but it may cause fluid overheating in the cooler. When the particle outlet is close to the reactor inlet, a large amount of SCW from reactor inlet will enter the particle outlet, which will decrease the particle transport efficiency. The current model can reasonably describe the flow dynamics characteristics of particle transport process, which may provide theoretical guidance for the design and optimization of slag-discharge system.

Osteodystrophies of jaws

Bone is a dense, semi rigid, porous, calcified connective tissue forming the major portion of the skeleton of most vertebrates. It consists of a dense organic matrix and an inorganic mineral component. Bone remodelling is a complex process by which old bone is continuously replaced by new tissue, which requires interaction between different cell phenotypes and is regulated by a variety of biochemical and mechanical factors. In a homeostatic equilibrium, the process of resorption and formation are balanced so that old bone is continuously replaced by new tissue and it adapts to mechanical load and strain. Several local and systematic factors which cause disturbances in bone resorption and deposition leads to abnormal or defective development of bone commonly termed as osteodystrophy - A defective ossification of bone usually is associated with disturbed calcium and phosphorus metabolism. The better understanding of molecular cellular biology and pathogenic mechanism aids to define the abnormalities in osteoblastic and osteoclastic lineages and to develop new therapeutic approaches.

Measuring Changes in Electrical Impedance During Cell-Mediated Mineralization.

Background: The fundamental electrical properties of bone have been attributed to the organic collagen and the inorganic mineral component; however, contributions of individual components within bone tissue toward the measured electrical properties are not known. In our study, we investigated the electrical properties of cell-mediated mineral deposition process and compared our results with cell-free mineralization. Materials and Methods: Saos-2 cells encapsulated within gelatin methacrylate (GelMA) hydrogels were chemically stimulated in osteogenic medium for a period of 4 weeks. The morphology, composition, and mechanical properties of the mineralized constructs were characterized using bright-field imaging, scanning electron microscopy (SEM) energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy (FITR), nuclear magnetic resonance spectroscopy (NMR), micro-CT, immunostaining, and mechanical compression tests. In parallel, a custom-made device was used to measure the electrical impedance of mineralized constructs. All results were compared with cell-free GelMA hydrogels mineralized through the simulated body fluid approach. Results: Results demonstrate a decrease in the electrical impedance of deposited mineral in both cell-mineralized and cell-free mineralized samples. Conclusions: This study establishes a model system to investigate in vivo and in vitro mineralization processes.

An experimental study on oxidizer treatment used to improve the seepage capacity of coal reservoirs

It is difficult to stimulate coal reservoirs in physical approaches, and the recovery factor of coalbed methane (CBM) can be enhanced by applying strong oxidizers through oxidation to stimulate coal reservoirs. At present, however, there have been very few studies on the oxidation of CBM and fewer experimental studies for systematically evaluating the effect of oxidation on the seepage capacity of coal reservoirs. In this paper, the coal samples taken from coal seams of the Jurassic Xishanyao Formation in the Heishan Coal Mine, Toksun, Xinjiang, were selected as the study objects. Hydrogen peroxide solution immersion experiments were carried out on columnar and powdered coal samples, respectively to measure the permeability of columnar coal samples, the dissolution rate of powdered coal samples and the property parameters of hydrogen peroxide solution. Then, the reaction mechanisms between coal samples and hydrogen peroxide and the mechanisms to improve the seepage capacity of coal reservoirs were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectrum and wetting angle measurement. Finally, the stimulation effect of oxidation was compared with that of acidification. The following research results were obtained. (1) The permeability of coal samples is increased significantly after oxidation to 1.4–3.2 times the original permeability. (2) A large number of micro-fractures and dissolved pores are formed in the coal samples after oxidation, and consequently pore connectivity is improved greatly. Thus, the amount of associative hydroxyl and carboxyl functional groups on the surface of the coal samples increases, and the water wettability on the surface reduces. (3) Organic matters and pyrites are oxidized and consumed easily, and the generated H+ and micro-molecular aliphatic acids further dissolve inorganic mineral components. (4) Oxidation also has the advantage of acidification for dissolving inorganic mineral components, so there is a low and controllable probability of generating coal powder. In conclusion, applying strong oxidizers has the potential to become a new technology for coal reservoir stimulation.