Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.521
Filtrar
1.
Curr Microbiol ; 81(5): 109, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38466427

RESUMO

Bacteria producing urea amidohydrolases (UA) and carbonic anhydrases (CA) are of great importance in civil engineering as these enzymes are responsible for microbially induced calcium carbonate precipitation (MICCP). In this investigation, genomic insights of Bacillus paranthracis CT5 and the expression of genes underlying in MICCP were studied. B. paranthracis produced a maximum level of UA (669.3 U/ml) and CA (125 U/ml) on 5th day of incubation and precipitated 197 mg/100 ml CaCO3 after 7 days of incubation. After 28 days of curing, compressive strength of bacterial admixed and bacterial cured (B-B) specimens was 13.7% higher compared to water-mixed and water-cured (W-W) specimens. A significant decrease in water absorption was observed in bacterial-cured specimens compared to water-cured specimens after 28 days of curing. For genome analysis, reads were assembled de novo producing 5,402,771 bp assembly with N50 of 273,050 bp. RAST annotation detected six amidohydrolase and three carbonic anhydrase genes. Among 5700 coding sequences found in genome, COG gene annotation grouped 4360 genes into COG categories with highest number of genes to transcription (435 genes), amino acid transport and metabolism (362 genes) along with cell wall/membrane/envelope biogenesis and ion transport and metabolism. KEGG functional classification predicted 223 pathways consisting of 1,960 genes and the highest number of genes belongs to two-component system (101 genes) and ABC transporter pathways (98 genes) enabling bacteria to sense and respond to environmental signals and actively transport various minerals and organic molecules, which facilitate the active transport of molecules required for MICCP.


Assuntos
Bacillus , Biomineralização , Anidrases Carbônicas , Bactérias/metabolismo , Carbonato de Cálcio/química , Anidrases Carbônicas/genética , Anidrases Carbônicas/metabolismo , Anotação de Sequência Molecular , Água/metabolismo , Urease
2.
J R Soc Interface ; 21(212): 20230597, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38471532

RESUMO

The sponge-like biomineralized calcite materials found in echinoderm skeletons are of interest in terms of both structure formation and biological function. Despite their crystalline atomic structure, they exhibit curved interfaces that have been related to known triply periodic minimal surfaces. Here, we investigate the endoskeleton of the sea urchin Cidaris rugosa that has long been known to form a microstructure related to the Primitive surface. Using X-ray tomography, we find that the endoskeleton is organized as a composite material consisting of domains of bicontinuous microstructures with different structural properties. We describe, for the first time, the co-occurrence of ordered single Primitive and single Diamond structures and of a disordered structure within a single skeletal plate. We show that these structures can be distinguished by structural properties including solid volume fraction, trabeculae width and, to a lesser extent, interface area and mean curvature. In doing so, we present a robust method that extracts interface areas and curvature integrals from voxelized datasets using the Steiner polynomial for parallel body volumes. We discuss these very large-scale bicontinuous structures in the context of their function, formation and evolution.


Assuntos
Carbonato de Cálcio , Ouriços-do-Mar , Animais , Carbonato de Cálcio/química
3.
MedEdPORTAL ; 20: 11385, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38445069

RESUMO

Introduction: Chalk talks are effective teaching tools in the clinical setting. However, data on optimal strategies for teaching medical educators how to develop and deliver them are limited. We designed and implemented two 50-minute workshops to help subspecialty fellows across GME create and deliver a chalk talk. Methods: The first workshop comprised a demonstration of an effective chalk talk and a discussion of best practices for creating chalk talks; the second was a practice session where fellows presented their chalk talks and received feedback from faculty and peers. We evaluated pre- and postworkshop confidence in the ability to create and deliver a chalk talk and develop learning objectives. Secondary outcomes were faculty and peer evaluations of the chalk talks. Results: Eighteen of 33 participants (54% response rate) completed both pre- and postsession surveys. Fellows reported improved confidence in their ability to create a chalk talk (22% vs. 83%, p < .001), deliver a chalk talk (17% vs. 83%, p < .001), and develop well-written learning objectives (11% vs. 83%, p < .001). After the workshop, participants were more likely to correctly identify a chalk talk that made use of an advanced organizer (67% vs. 89%, p < .05). Thirty-eight faculty and peers completed feedback evaluations of participants' chalk talks; most rated fellows' chalk talks highly in domains of content, delivery, design, learning objectives, and engagement. Discussion: The incorporation of these workshop within a course on medical education can effectively develop clinical teaching skills among subspecialty fellows in GME.


Assuntos
Educação Médica , Aprendizagem , Humanos , Carbonato de Cálcio , Competência Clínica , Docentes
4.
Sci Rep ; 14(1): 5649, 2024 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-38454106

RESUMO

The relationship between energy reserves of cold-water corals (CWCs) and their physiological performance remains largely unknown. In addition, it is poorly understood how the energy allocation to different metabolic processes might change with projected decreasing food supply to the deep sea in the future. This study explores the temporal and spatial variations of total energy reserves (proteins, carbohydrates and lipids) of the CWC Desmophyllum dianthus and their correlation with its calcification rate. We took advantage of distinct horizontal and vertical physico-chemical gradients in Comau Fjord (Chile) and examined the changes in energy reserves over one year in an in situ reciprocal transplantation experiment (20 m vs. 300 m and fjord head vs. mouth). Total energy reserves correlated positively with calcification rates. The fast-growing deep corals had higher and less variable energy reserves, while the slower-growing shallow corals showed pronounced seasonal changes in energy reserves. Novel deep corals (transplanted from shallow) were able to quickly increase both their calcification rates and energy reserves to similar levels as native deep corals. Our study shows the importance of energy reserves in sustaining CWC growth in spite of aragonite undersaturated conditions (deep corals) in the present, and potentially also future ocean.


Assuntos
Antozoários , Animais , Antozoários/fisiologia , Estuários , Calcificação Fisiológica/fisiologia , Água , Carbonato de Cálcio , Recifes de Corais
5.
PLoS One ; 19(3): e0296437, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38512878

RESUMO

Microbially induced calcium carbonate precipitation (MICP) is an environmentally friendly technology that improves soil permeability resistance through biocementation. In this study, 2D microscopic analysis and 3D volume reconstruction were performed on river sand after 24 cycles of bio-treatment based on stacked images and computed tomography (CT) scanning data, respectively, to extract biocementation patterns between particles. Based on the mutual validation findings of the two techniques, three patterns in the biocemented sand were identified as G-C-G, G-C, and G-G. Specifically, 2D microscopic analysis showed that G-C-G featured multi-particle encapsulation and bridging, with a pore filling ratio of 81.2%; G-C was characterized by locally coated particle layers, with a pore filling ratio of 19.7%; and the G-G was marked by sporadic filling of interparticle pores, with a pore filling ratio of 11.7%. G-C-G had the best cementation effect and permeability resistance (effective sealing rate of 68.5%), whereas G-C (effective sealing rate of 2.4%) had a relatively minor contribution to pore-filling and flow sealing. 3D volume reconstruction showed that G-C-G had the highest pore filling rate, followed by G-G and G-C. The average filling ratios of area and volume for G-C-G were 83.979% and 77.257%, respectively; for G-G 20.360% and 23.600%; and for G-C 11.545% and 11.250%. The analysis of the representative element volume (REV) was conducted, and the feasibility and reliability of the micro-scale pattern extraction results were confirmed to guide the analysis of macro-scale characteristics. The exploration of the effectiveness of cementation patterns in fluid sealing provides valuable insights into effective biocementation at the pore scale of porous media, which may inspire future research.


Assuntos
Carbonato de Cálcio , Areia , Cimentação , Reprodutibilidade dos Testes , Tomografia Computadorizada por Raios X , Precipitação Química
6.
Surg Radiol Anat ; 46(3): 391-398, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38436731

RESUMO

PURPOSE: To investigate the current practices in anatomy teaching at French universities in 2023. METHODS: On January 10, 2023, a questionnaire was sent to all members of the official list of the French Medical College of Professors of Anatomy. Each Anatomy centre was asked to complete this online form only once. The questionnaire covered several key themes, including broad questions, dissections practices, "virtual" dissections, teaching methods and teaching staff. RESULTS: The questionnaire was completed by 26/28 anatomy centres. Access to body donor dissection is reported to be mandatory in 15 of the 26 centers (58%), optional in 10 centers (38%), and "tolerated" in one center (4%). Fifteen of 26 centers (58%) reported having a virtual dissection table for teaching anatomy. Concerning the teaching of anatomy via live ultrasound, 10 out of 26 centers (38%) reported providing it. Regarding the teaching methods used for medical students, chalk and board lectures are the most common method, although the intensity of use varies. Most lectures are given with chalk and board in 42% (11/26) of the centers. In about 73% (19/26) of the centers, tablet lectures are used. Regarding anatomy teachers, it was reported that in 24/26 anatomy centres (92%), more than 50% of the courses for medical students are taught by professors holding the chair of anatomy (21/26 professors (81%), 3/26 associate professors (12%)). CONCLUSION: The present study endeavors to contribute to the existing body of knowledge on anatomy education by offering insights into the current practices in French universities.


Assuntos
Anatomia , Educação de Graduação em Medicina , Estudantes de Medicina , Humanos , Educação de Graduação em Medicina/métodos , Dissecação/educação , Currículo , França , Inquéritos e Questionários , Carbonato de Cálcio , Anatomia/educação , Ensino
7.
Poult Sci ; 103(4): 103558, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38442559

RESUMO

Iron is routinely supplemented in broiler feeds aiming to prevent dietary deficiencies. Limestone and phosphates are very rich in Fe; however, its contribution from these sources have not been thoroughly investigated with chickens. The present research was conducted to evaluate live performance and blood parameters of broilers when using limestone and dicalcium phosphate as sources of Fe. A total of 576 one-day-old male Cobb x Cobb 500 were allocated into a total of 72 battery cages, 6 treatments with 12 replication cages of 8 chicks at placement. Chicks were fed diets formulated with corn, soybean meal (SBM) with laboratory grade calcium carbonate and phosphoric acid (having traces of Fe). All chicks were fed a common prestarter without Fe supplementation (analyzed total 58.2 ± 2.4 mg/kg Fe) from placement to 7 d. Allocation of birds to dietary treatments was completely randomized on day 8. Treatments had increasing Fe derived from commercial limestone and dicalcium phosphate (analyzed Fe 7,218 and 4,783 mg/kg, respectively) progressively replacing calcium carbonate and phosphoric acid to provide graded increases in total Fe (analyzed Fe in the feeds were 57.6 ± 2.1, 92.0 ± 2.3, 124.1 ± 2.7, 159.3 ± 3.1, 187.2 ± 3.2, 223.7 ± 3.6 mg/kg, respectively). There were no effects of dietary Fe on live performance, hematocrit, and hemoglobin the end of the study on day 28 (P > 0.05). Increasing dietary Fe from commercial limestone and dicalcium phosphate led to a linear reduction in the percent ileal digestible Fe. However, linear increments in Fe retention, serum ferritin and liver Fe occurred when compared to feeds without Fe derived from limestone and phosphate dicalcium. It is concluded that Fe from limestone and dicalcium phosphate can be partially utilized by broiler chickens. It was estimated that the Fe retained from limestone and dicalcium phosphate is of 1.9%. Broilers fed corn-soy feeds (58.2 mg/kg Fe) do not require supplemental Fe.


Assuntos
Carbonato de Cálcio , Fosfatos de Cálcio , Galinhas , Ácidos Fosfóricos , Animais , Masculino , Ferro , Dieta/veterinária , Suplementos Nutricionais , Fosfatos , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Digestão
8.
Environ Sci Pollut Res Int ; 31(10): 15716-15732, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38305969

RESUMO

Tongling is a significant non-ferrous metal mining city in China, which produces waste that negatively impacts the area's water environment. It is essential to comprehend the hydrochemical properties and formation processes of groundwater to safeguard and utilize it efficiently. We explored major ions, strontium, and its isotopes in water and river-bottom samples from the northern (i.e., A-A' section) and southern (i.e., B-B' section) areas. The hydrochemical facies show the mining activities have a greater impact on surface water than on groundwater. Groundwater hydrochemical formation results from several factors, with water-rock interaction and ion exchange being primary. Additionally, the dissolution of calcite, dolomite, and feldspar, oxidation of pyrite, and hydrolysis of carbonate minerals also impact the formation of groundwater chemistry. Our analysis of strontium and its isotopes indicates that carbonate dissolution primarily occurred in the recharge area; the runoff from the recharge to the discharge area results in the dissolution of certain silicate rocks; calcite dissolution sources account for > 70% contribution in both surface water and groundwater water-rock interactions, whereas silicate rock dissolution sources and dolomite dissolution sources account for < 30%. Due to changed order of dissolved carbonate and silicate minerals during groundwater flow, the distribution of strontium and its isotopes in the A-A' section is opposite to that in the B-B' section. The findings provide a basis for developing, utilizing, managing, and protecting groundwater resources, especially in similar mining areas.


Assuntos
Água Subterrânea , Magnésio , Poluentes Químicos da Água , Monitoramento Ambiental/métodos , Poluentes Químicos da Água/análise , Carbonato de Cálcio/análise , Água Subterrânea/química , Mineração , Isótopos de Estrôncio/análise , Minerais/análise , Estrôncio/análise , Carbonatos/análise , Isótopos/análise , Silicatos/análise , Água/análise
9.
Commun Biol ; 7(1): 246, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38424314

RESUMO

Coral reefs, the largest bioconstruction on Earth, are formed by calcium carbonate skeletons of corals. Coral skeleton formation commonly referred to as calcification occurs in a specific compartment, the extracellular calcifying medium (ECM), located between the aboral ectoderm and the skeleton. Calcification models often assume a direct link between the surrounding seawater and the ECM. However, the ECM is separated from the seawater by several tissue layers and the cœlenteron, which contains the cœlenteric fluid found in both polyps and cœnosarc (tissue connecting the polyps). Symbiotic dinoflagellate-containing cells line the cœlenteron and their photosynthetic activity contributes to changes in the chemistry of the cœlenteric fluid, particularly with respect to pH. The aim of our study is to compare cœlenteron pH between the cœnosarc and polyps and to compare areas of high or low dinoflagellate density based on tissue coloration. To achieve this, we use liquid ion exchange (LIX) pH microsensors to profile pH in the cœlenteron of polyps and the cœnosarc in different regions of the coral colony in light and darkness. We interpret our results in terms of what light and dark exposure means for proton gradients between the ECM and the coelenteron, and how this could affect calcification.


Assuntos
Antozoários , Calcinose , Animais , Concentração de Íons de Hidrogênio , Carbonato de Cálcio , Recifes de Corais , Água do Mar
10.
Appl Microbiol Biotechnol ; 108(1): 202, 2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38349550

RESUMO

Aureobasidium is omnipresent and can be isolated from air, water bodies, soil, wood, and other plant materials, as well as inorganic materials such as rocks and marble. A total of 32 species of this fungal genus have been identified at the level of DNA, of which Aureobasidium pullulans is best known. Aureobasidium is of interest for a sustainable economy because it can be used to produce a wide variety of compounds, including enzymes, polysaccharides, and biosurfactants. Moreover, it can be used to promote plant growth and protect wood and crops. To this end, Aureobasidium cells adhere to wood or plants by producing extracellular polysaccharides, thereby forming a biofilm. This biofilm provides a sustainable alternative to petrol-based coatings and toxic chemicals. This and the fact that Aureobasidium biofilms have the potential of self-repair make them a potential engineered living material avant la lettre. KEY POINTS: •Aureobasidium produces products of interest to the industry •Aureobasidium can stimulate plant growth and protect crops •Biofinish of A. pullulans is a sustainable alternative to petrol-based coatings •Aureobasidium biofilms have the potential to function as engineered living materials.


Assuntos
Aureobasidium , Biofilmes , Carbonato de Cálcio , Produtos Agrícolas , Gasolina
11.
PLoS One ; 19(2): e0295192, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38330093

RESUMO

This study presents a comprehensive analysis of rock properties for a selected group of six carbonate reservoir rock samples revealing complex structures at various length scales. Experimental laboratory methods as well as image analysis techniques were conducted in this study to characterize the macro- and micro-pores in mud- and grain-dominated limestones samples from the Upper Jurassic Arab Formation (Arab D member). Mercury Injection Capillary Pressure (MICP), porosimeter, and permeameter lab measurements were employed to assess the pore network heterogeneity and complexity. In addition, a multiscale rock imaging approach was implemented to detect grain and pore phases at several length scales using Thin Sections (TS), Scanning Electron Microscopy (SEM), Focused Ion Beam Scanning Electron Microscopy (FIB-SEM), as well as 3D X-ray Computed Tomography (CT), and micro-computed tomography images (MCT). Furthermore, the multifractal analysis method was applied on the MICP and FIB-SEM to characterize quantitatively the heterogeneity of the pores in the studied samples. Heterogeneous samples 3R, 4M, 5W, and 6M display the highest non-uniformity degree Δα values, falling within the range of [1.21, 1.39] based on FIB-SEM images. Samples 1G, 2R, 3R, and 5W exhibit more heterogeneous pore structure, with Δα values ranging from 0.73 to 1.49 based on the MICP experiments. The results and findings confirm the effectiveness of multifractal parameters Δα and the asymmetry degree in the vertical axis Δf(α) in quantifying and characterizing rock heterogeneity.


Assuntos
Carbonato de Cálcio , Carbonatos , Microtomografia por Raio-X/métodos , Emirados Árabes Unidos , Microscopia Eletrônica de Varredura
12.
Sci Rep ; 14(1): 4356, 2024 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-38388732

RESUMO

While microbial biogeochemical activities such as those involving denitrification and sulfate reduction have been considered to play important roles in material cycling in various aquatic ecosystems, our current understanding of the microbial community in groundwater ecosystems is remarkably insufficient. To assess the groundwater in the Ryukyu limestone aquifer of Okinawa Island, which is located in the southernmost region of Japan, we performed metagenomic analysis on the microbial communities at the three sites and screened for functional genes associated with nitrogen metabolism. 16S rRNA amplicon analysis showed that bacteria accounted for 94-98% of the microbial communities, which included archaea at all three sites. The bacterial communities associated with nitrogen metabolism shifted by month at each site, indicating that this metabolism was accomplished by the bacterial community as a whole. Interestingly, site 3 contained much higher levels of the denitrification genes such as narG and napA than the other two sites. This site was thought to have undergone denitrification that was driven by high quantities of dissolved organic carbon (DOC). In contrast, site 2 was characterized by a high nitrate-nitrogen (NO3-N) content and a low amount of DOC, and this site yielded a moderate amount of denitrification genes. Site 1 showed markedly low amounts of all nitrogen metabolism genes. Overall, nitrogen metabolism in the Ryukyu limestone aquifer was found to change based on environmental factors.


Assuntos
Água Subterrânea , Microbiota , Carbonato de Cálcio/metabolismo , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Bactérias , Água Subterrânea/química , Nitrogênio/metabolismo , Desnitrificação , Nitratos/metabolismo
13.
Environ Sci Pollut Res Int ; 31(11): 16583-16600, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38321279

RESUMO

The exploitation of coal resources has disturbed the equilibrium of the original groundwater system, resulting in a perturbation of the deep groundwater dynamic conditions and hydrochemical properties. Exploring the formation of mine water chemistry under the conditions of deep coal seam mining in the Ordos Basin provides a theoretical basis for the identification of sources of mine water intrusion and the development and utilization of water resources. This paper takes Longwanggou Coal Mine as the research area, collects a total of 106 groups of water samples from the main water-filled aquifers, comprehensively uses Piper trilinear diagram, Gibbs diagram, ion correlation, ion ratio coefficient and mineral saturation index analysis, and carries out inverse geochemical modeling with PHREEQC software, so as to analyze the hydrochemical characteristics and causes of the main water-filled aquifers in deep-buried coal seams in the research area. The results show that the main hydrochemical processes in the study area are leaching and cation exchange, and the groundwater is affected by carbonate (calcite, dolomite), silicate (gypsum) and evaporite. Calculations of mineral saturation indices and PHREEQC simulations have led to the conclusion that the dissolution of rock salt and gypsum in groundwater accounts for most of the ionic action. Na+, Cl- and SO42- are mainly derived from the dissolution of rock salt and gypsum minerals, while Ca2+ and Mg2+ are mostly derived from the dissolution of dolomite and calcite. The results of the inverse geochemical modeling are consistent with the theoretical analysis.


Assuntos
Água Subterrânea , Magnésio , Poluentes Químicos da Água , Monitoramento Ambiental/métodos , Sulfato de Cálcio/análise , Poluentes Químicos da Água/análise , Água Subterrânea/química , Carbonato de Cálcio/análise , Água/análise , Carvão Mineral/análise
14.
Environ Sci Pollut Res Int ; 31(11): 16206-16215, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38334921

RESUMO

This paper has presented a mini review of previously published articles dealing with bio-cement production using enzyme-induced calcite precipitation (EICP) technique. EICP is a biological, sustainable, and natural way of producing calcite without the direct involvement of microorganisms from urea and calcium chloride using urease enzyme in water-based solution with minimum energy consumption and eco-friendly. Calcite is a renewable bio-material that acts as a binder to improve the mechanical properties of soils like strength, stiffness, and water permeability. EICP has many real applications such as fugitive duct control with low cost comparing with water application or pouring, self-healing cracked concretes, and upgrade or change the low-volume road surfaces that are difficult for road constructions. The crystal structure of finally produced calcium carbonate (CaCO3), calcite is affected by the source of calcium ion; the calcite produced from calcium chloride has a rhombohedral crystal structure. The urease enzyme used for EICP applications could be produced in a laboratory-scale from different plant species, bacteria, some yeasts, fungi, tissues of humans, and invertebrates. Nevertheless, urease enzyme produced from jack beans has showed urease enzyme activity around 2700-3500U/g, and the tendency to replace the urease enzyme found in the global market. All urease enzymes have 12-nm size, and this smaller size makes EICP preferable for all types of soil or sands including fine and silt sands.


Assuntos
Carbonato de Cálcio , Areia , Humanos , Carbonato de Cálcio/química , Urease , Cloreto de Cálcio , Solo , Água
15.
Environ Sci Pollut Res Int ; 31(11): 17052-17063, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38334929

RESUMO

Improving the adsorption performance of wetland fillers is of great significance for enhancing pollutant removal in constructed wetlands. Currently, limited by complex preparation processes and high costs, large numbers of high adsorption fillers studied in lab are difficult to be applied in practical engineering. In this study, a newly low-cost and efficient phosphorus removal composite wetland filler (CFB) is prepared by using industrial and agriculture waste (steel slag and oyster shells) and natural ore (volcanic rock) as raw materials. The results show that phosphorus removal efficiency was largely enhanced by synergistic effects of steel slag, oyster shells, and volcanic rock, and it was mainly influenced by the proportion of each component of CFB. Based on the fitting of the classical isothermal equation, the adsorption capacity of CFB is 18.339 mg/g. The adsorption of phosphorus by CFB is endothermic and spontaneous, and there are heterogeneous surfaces and multi-layer adsorption processes, as well as pH value and temperature, are free from the influence on CFB phosphorus removal. During the practical wastewater application experiments, the phosphorus removal rate of the CFB-filled constructed wetland apparatus (CW-A) can reach 94.89% and is free from the influence on the removal of other pollutants (COD, TN, and NH3-N) by the system. Overall, the prepared CFB is of excellent decontamination effect, an extremely simple preparation process, low cost, and sound practical engineering application potential, providing new ideas and approaches for enhancing the phosphorus removal capacity and waste resource utilization of constructed wetland systems.


Assuntos
Poluentes Ambientais , Eliminação de Resíduos Líquidos , Eliminação de Resíduos Líquidos/métodos , Áreas Alagadas , Fósforo , Águas Residuárias , Excipientes , Carbonato de Cálcio , Aço , Nitrogênio/análise
16.
Sci Total Environ ; 921: 171060, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38378057

RESUMO

Bioremediation based on microbial-induced carbonate precipitation (MICP) was conducted in cadmium and lead contaminated soil to investigate the effects of MICP on Cd and Pb in soil. In this study, soil indigenous nitrogen was shown to induce MICP to stabilize heavy metals without inputting exogenous urea. The results showed that applying Bacillus pasteurii coupled with CaCl2 reduced Cd and Pb bioavailability, which could be clarified through the proportion of exchangeable Cd and Pb in soil decreasing by 23.65 % and 12.76 %, respectively. Moreover, B. pasteurii was combined separately with hydroxyapatite (HAP), eggshells (ES), and oyster shells (OS) to investigate their effects on soil heavy metals' chemical fractions, toxicity characteristic leaching procedure (TCLP)-extractable Cd and Pb as well as enzymatic activity. Results showed that applying B. pasteurii in soil significantly decreased the heavy metals in the exchangeable fraction and increased them in the carbonate phase fraction. When B. pasteurii was combined with ES and OS, the content of carbonate-bound Cd increased by 114.72 % and 118.81 %, respectively, significantly higher than when B. pasteurii was combined with HAP, wherein the fraction of carbonate-bound Cd increased by 86 %. The combination of B. pasteurii and biogenic calcium effectively reduced the leached contents of Cd and Pb in soil, and the TCLP-extractable Cd and Pb fractions decreased by 43.88 % and 30.66 %, respectively, in the BP + ES group and by 52.60 % and 41.77 %, respectively, in the BP + OS group. This proved that MICP reduced heavy metal bioavailability in the soil. Meanwhile, applying B. pasteurii and calcium materials significantly increased the soil urease enzyme activity. The microstructure and chemical composition of the soil samples were studied, and the results from scanning electron microscope, Fourier transform infra-red spectroscopy, and X-ray diffraction demonstrated the MICP process and identified the formation of CaCO3, Ca0.67Cd0.33CO3, and PbCO3 in heavy metal-contaminated soil.


Assuntos
Metais Pesados , Poluentes do Solo , Sporosarcina , Cádmio/análise , Cálcio , Chumbo , Solo/química , Metais Pesados/análise , Bactérias , Carbonato de Cálcio , Biodegradação Ambiental , Carbonatos , Poluentes do Solo/análise
17.
Biomed Mater ; 19(3)2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38422521

RESUMO

Calcium carbonate (CaCO3), which exhibits excellent biocompatibility and bioactivity, is a well-established bone filling material for bone defects. Here, we synthesized CaCO3microspheres (CMs) to use as an intelligent carrier to load bone morphogenetic protein-2 (BMP-2). Subsequently, drug-loaded CMs and catalase (CAT) were added to methacrylated gelatin (GelMA) hydrogels to prepare a composite hydrogel for differential release of the drugs. CAT inside hydrogels was released with a fast rate to eliminate H2O2and generate oxygen. Constant BMP-2 release from CMs induced rapid osteogenesis. Resultsin vitroindicated that the composite hydrogels efficiently reduced the level of intracellular reactive oxygen species, preventing cells from being injured by oxidative stress, promoting cell survival and proliferation, and enhancing osteogenesis. Furthermore, animal experiments demonstrated that the composite hydrogels were able to inhibit the inflammatory response, regulate macrophage polarization, and facilitate the healing of bone defects. These findings indicate that a multi-pronged strategy is greatly expected to promote the bone healing by modulating pathological microenvironments.


Assuntos
Hidrogéis , Osteogênese , Animais , Hidrogéis/farmacologia , Osso e Ossos , Gelatina , Carbonato de Cálcio , Regeneração Óssea
18.
Geobiology ; 22(1): e12586, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38385602

RESUMO

The formation of skeletal structures composed of different calcium carbonate polymorphs (e.g. aragonite and calcite) appears to be both biologically and environmentally regulated. Among environmental factors influencing aragonite and calcite precipitation, changes in seawater conditions-primarily in the molar ratio of magnesium and calcium during so-called 'Calcite' (mMg:mCa below 2) or 'Aragonite' seas (mMg:mCa above 2)-have had profound impacts on the distribution and performance of marine calcifiers throughout Earth's history. Nonetheless, the fossil record shows that some species appear to have counteracted such changes and kept their skeleton polymorph unaltered. Here, the aragonitic octocoral Heliopora coerulea and the aragonitic scleractinian Montipora digitata were exposed to Calcite Sea-like mMg:mCa with various levels of magnesium and calcium concentration, and changes in both the mineralogy (i.e. CaCO3 polymorph) and gene expression were monitored. Both species maintained aragonite deposition at lower mMg:mCa ratios, while concurrent calcite presence was only detected in M. digitata. Despite a strong variability between independent experimental replicates for both species, the expression for a set of putative calcification-related genes, including known components of the M. digitata skeleton organic matrix (SkOM), was found to consistently change at lower mMg:mCa. These results support the previously proposed involvements of the SkOM in counteracting decreases in seawater mMg:mCa. Although no consistent expression changes in calcium and magnesium transporters were observed, down-regulation calcium channels in H. coerulea in one experimental replicate and at an mMg:mCa of 2.5, pointing to a possible active calcium uptake regulation by the corals under altered mMg:mCa.


Assuntos
Antozoários , Carbonato de Cálcio , Animais , Carbonato de Cálcio/análise , Cálcio/metabolismo , Antozoários/química , Antozoários/metabolismo , Magnésio/análise , Oceanos e Mares
19.
Sci Rep ; 14(1): 2710, 2024 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-38302670

RESUMO

Extensive research has provided a wealth of data on prokaryotes in caves and their role in biogeochemical cycles. Ice caves in carbonate rocks, however, remain enigmatic environments with limited knowledge of their microbial taxonomic composition. In this study, bacterial and archaeal communities of the Obstans Ice Cave (Carnic Alps, Southern Austria) were analyzed by next-generation amplicon sequencing and by cultivation of bacterial strains at 10 °C and studying their metabolism. The most abundant bacterial taxa were uncultured Burkholderiaceae and Brevundimonas spp. in the drip water, Flavobacterium, Alkanindiges and Polaromonas spp. in the ice, Pseudonocardia, Blastocatella spp., uncultured Pyrinomonadaceae and Sphingomonadaceae in carbonate precipitates, and uncultured Gemmatimonadaceae and Longimicrobiaceae in clastic cave sediments. These taxa are psychrotolerant/psychrophilic and chemoorganotrophic bacteria. On a medium with Mg2+/Ca2+ = 1 at 21 °C and 10 °C, 65% and 35% of the cultivated strains precipitated carbonates, respectively. The first ~ 200 µm-size crystals appeared 2 and 6 weeks after the start of the cultivation experiments at 21 °C and 10 °C, respectively. The crystal structure of these microbially induced carbonate precipitates and their Mg-content are strongly influenced by the Mg2+/Ca2+ ratio of the culture medium. These results suggest that the high diversity of prokaryotic communities detected in cryogenic subsurface environments actively contributes to carbonate precipitation, despite living at the physical limit of the presence of liquid water.


Assuntos
Bactérias , Carbonato de Cálcio , Gelo , Archaea/classificação , Bactérias/classificação , Carbonato de Cálcio/metabolismo , Filogenia , Extremófilos/classificação
20.
Sci Total Environ ; 922: 171245, 2024 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-38408656

RESUMO

Cadmium (Cd) and arsenic (As) are precedence-controlled contaminants in paddy soils, that can easily accumulate in rice grains. Limestone and sepiolite (LS) compound passivator can obviously reduce Cd uptake in rice, whereas Si fertilizer can effectively decrease rice As uptake. Here, the synergistic effects of the LS compound passivator coupled with Si fertilizer (LSCS) on the soil pH and availability of Si, Cd, and As, as well as rice grain Cd and As accumulation and its health risk were studied based on a 3-year consecutive field experiment. The results showed that the LSCS performed the best in terms of synchronously decreasing soil Cd and As availability and rice Cd and As uptake. In the LSCS treatments, soil pH gradually decreased with the rice-planting season, while soil available Cd and As contents gradually increased, suggesting that the influence of LSCS on Cd and As availability gradually weakened with rice cultivation. Nonetheless, the contents of Cd and inorganic As (i-As) in rice grains treated with LSCS were slightly affected by cultivation but were significantly lower than the single treatments of LS compound passivator or Si fertilizer. According to the Cd and As limit standards in food (GB2762-2022), the Cd and i-As content in rice grains can be lowered below the standard by using the 4500 kg/hm2 LS compound passivator coupled with 90 kg/hm2 Si fertilizer in soil and spraying 0.4 g/L Si fertilizer on rice leaves for at least three years. Furthermore, health risk evaluation revealed that LSCS treatments significantly reduced the estimated daily intake, annual excess lifetime cancer risk, and hazard quotient of Cd and i-As in rice grains. These findings suggest that LSCS could be a viable approach for reducing Cd and As accumulation in rice grains and lowering the potential health risks associated with rice.


Assuntos
Arsênio , Silicatos de Magnésio , Oryza , Poluentes do Solo , Cádmio/análise , Arsênio/análise , Oryza/química , Silício/química , Fertilizantes/análise , Poluentes do Solo/análise , Solo/química , Carbonato de Cálcio
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...