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1.
J Colloid Interface Sci ; 630(Pt B): 11-20, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36308804

RESUMO

Natural green algaes (GAs) was treated with NaCl solution to prepare metal- silicates (S-C-FeSi-3 and S-C-CuSi-3) with high electrochemical performance. Then, the as-synthesized samples were soaked in NaOH solution to obtain etched metal silicates (e-S-C-FeSi-3 and e-S-C-CuSi-3). This novel method was used to generate a more porous structure with a higher specific surface area. In the three-electrode system, e-S-C-FeSi-3 and e-S-C-CuSi-3 showed the best electrochemical performance (476 F g-1 and 458 F g-1 at 0.5 A g-1, 96 % and 97% after 10,000 cycles, respectively). The solid-state hybrid supercapacitor (HSC) devices (denoted as e-S-C-FeSi-3//AC and e-S-C-CuSi-3//AC), manufactured by metal- silicates and activated carbon (AC), were tested in a two-electrode system. e-S-C-MSi-3//AC exhibited much better electrochemical properties such as areal specific capacitances (603 and 615 mF cm-2 at 2 mA cm-2), energy densities (4.57 and 4.43 Wh m-2 at the power density of 19.2 and 21.0 W m-2) and cycle performances (74.5 % and 76.3 % after 6,000 cycles) than those of C-MSi-3//AC, e-C-MSi-3//AC and S-C-MSi-3//AC (M = Fe and Cu). This study confirms that supercapacitors with excellent electrochemical performance can be prepared by naturally polluted GAs. Furthermore, treatment with porogens is shown to be an effective method to enhance the electrochemical properties of metal- silicates and to prepare electrode materials applied for high-performance supercapacitors.


Assuntos
Clorófitas , Silicatos , Capacitância Elétrica , Eletrodos , Metais , Carvão Vegetal
2.
J Hazard Mater ; 442: 130032, 2023 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-36166903

RESUMO

Dicalcium silicate (C2S) is known to incorporate potentially hazardous metals (Cr and V) in a belite-rich cementitious system. The effect of the electrovalence nature of V and Cr on C2S polymorphs' (α´, ß, γ) stability under oxidizing and reducing conditions as well as their reactivity are systematically investigated via analyzing oxidation states, phase composition, bonding system, and microstructure as well as oxide composition quantitively. It is shown that C2S can incorporate Cr (VI) and V(V) consequently leading to stabilization of α´, ß-C2S. Instead, Cr (II, III) and V < (V) tend not to substitute in C2S. Despite reactive polymorphs (α´, ß-C2S) stability due to Cr (VI) and V(V) incorporation, the early age (48-72 h) C2S reactivity is drastically reduced due to Cr (VI) and V (V) incorporation. Moreover, one batch leaching test revealed that the V (V) leaching is inversely proportional to aqueous Ca2+ ion at pH > 12 while Cr leaching is sensitive to its oxidation state, and dissolution of C2S. Even though C2S can incorporate Cr (VI) and V (V) ions, the final leaching is governed by the immobilization potential of C-S-H gel, pH as well as types of calcium chromate and vanadate complexes.


Assuntos
Silicatos , Vanadatos , Silicatos/química , Óxidos , Oxirredução , Cromo/química
3.
Braz. j. oral sci ; 21: e223816, jan.-dez. 2022. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1354701

RESUMO

Direct pulp capping induces a local inflammatory process. Several biomaterials have been used for this procedure. The aim of this study was to compare the dentinal bridge thickness using three different pulp capping biomaterials with the conventional technique (high speed diamond bur) or Er-Yag laser, 1 month after pulp effraction. Materials and Methods: Forty two Class V cavities were prepared on the buccal surface of 4 maxillary incisors and 2 mandibular incisors of New Zealand rabbits. Specimens were divided into 6 treatment groups. Teeth were treated with: In Group 1: Er-Yag laser and Biodentine® (Septodont), in Group 2: Er: Yag laser and calcium hydroxide (Dycal® Dentsply), in Group 3: Er: Yag laser and adhesive system (Prime& Bond® NT Dentsply), in Group 4: high speed diamond bur and Biodentine® (Septodont), in Group 5: high speed diamond bur and calcium hydroxide (Dycal® Dentsply), and in Group 6: high speed diamond bur and adhesive system (Prime& Bond® NT Dentsply). The preparation was done with copious irrigation. The animals were sacrificed at 30 days and the teeth were extracted and prepared for histological analysis. Results: In the group of « laser Er-Yag ¼, iatrogenic pulpal wounds treated with Biodentine® were covered with a thick hard tissue barrier after 1 month. The difference was not significant with the groups of Dycal® used with Er: Yag laser and high speed diamond bur. Prime& Bond® NT Dentsply specimens showed a thin dentinal bridge layer. Conclusion: At 1 month, Er-Yag laser proved to be useful with Biodentine® for direct pulp capping procedures


Assuntos
Animais , Coelhos , Ácidos Polimetacrílicos , Hidróxido de Cálcio , Silicatos , Compostos de Cálcio , Capeamento da Polpa Dentária , Lasers de Estado Sólido
4.
Int J Nanomedicine ; 17: 5187-5205, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36388876

RESUMO

Background: Mesoporous calcium-silicate nanoparticles (MCSNs) are advanced biomaterials that have been used to control drug delivery for many years. Ultrasmall Prussian blue nanoparticles (UPBNPs) showed high peroxidase and catalase-like activities. This study evaluated the antibacterial and antibiofilm properties, mechanism and cytotoxicity of UPBNPs-MCSNs composites synthesized by both as precursors. Methods: UPBNPs-MCSNs were prepared and characterized. The antibacterial effect of UPBNPs-MCSNs was evaluated by the MTT assay and CFU counting method, and their biosafety was tested by CCK8. Then explore the antibacterial mechanism, including TEM observation of bacterial morphology, and detection of bacterial ROS, LPO and GSH levels. The antibiofilm activity of UPBNPs-MCSNs was tested by E. faecalis biofilm model in human roots. The roots were pretreated with materials and cultured with E. faecalis, and the survival of E. faecalis on the root canal wall was observed by SEM and CLSM. Results: The results showed that UPBNPs-MCSNs had potent antibacterial and antibiofilm activities. They can aggregate on the dentin surface and significantly inhibit E. faecalis adhesion and colonization. Their antibacterial activity is as effective as NaClO and calcium hydroxide (CH), can significantly prolong the time of bacterial colonization than CH, but have lower cytotoxicity to normal cells. We found that UPBNPs-MCSNs trigger a like classic ferroptosis pathway in bacteria. UPBNPs-MCSNs can induce bacteria to produce ROS and LPO, and reduce GSH level. Moreover, we observed that the metal ions chelator and the antioxidant could block their antibacterial activity. Conclusion: These results reveal that UPBNPS-MCSNs have high antibacterial and antibiofilm, and can mediate the bacterial redox pathway ROS/GSH like the classical pathway of ferroptosis, providing a theoretical basis for them to develop into a safe and effective novel root canal disinfectant.


Assuntos
Ferroptose , Nanopartículas , Humanos , Enterococcus faecalis , Cálcio/farmacologia , Espécies Reativas de Oxigênio/farmacologia , Silicatos/farmacologia , Antibacterianos/farmacologia , Oxirredução
5.
Soft Matter ; 18(44): 8486-8503, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36321471

RESUMO

Soft, conductive, and stretchable hydrogels offer a broad variety of applications, including skin-interfacing electrodes, biomonitoring patches, and electrostimulation. Despite rapid developments over the last decades, a combination of good electrical and mechanical properties, low-cost fabrication, and biocompatibility is yet to be demonstrated. Also, the current methods for deposition and patterning of these hydrogels are manual, and there is a need toward autonomous and digital fabrication techniques. In this work, we demonstrate a novel Gallium (Ga) embedded sodium-alginate-polyacrylamide-LAPONITE® (Ga-SA-PAAM-La) hydrogel, that is ultra-stretchable (Maximum strain tolerance of∼985%), tough (toughness ∼30 kJ m-3), bio-adhesive (adhesion energy ∼216 J m-2), conductive, and digitally printable. Ga nanoparticles are used as radical initiators. By adjusting the sonication parameters, we control the solution viscosity and curing time, thus allowing us to prepare pre-polymers with the desired properties for casting, or digital printing. These hydrogels benefit from a triple-network structure due to the role of Ga droplets as crosslinkers besides BIS (N,N'-methylene-bis-acrylamide) and LAPONITE®, thus resulting in tough composite hydrogels. The inclusion of LAPONITE® into the hydrogel network improved its electrical conductivity, adhesion, digital printability, and its mechanical properties, (>6× compared to the same hydrogel without LAPONITE®). As electrodes in the electrocardiogram, the signal-to-noise ratio was surprisingly higher than the medical-grade Ag/AgCl electrodes, which are applied for monitoring muscles, heart, respiration, and body joint angle through EMG, ECG, and bioimpedance measurements. The results obtained prove that such digitally printed conductive and tough hydrogels can be used as potential electrodes and sensors in practical applications in the next generation of printed wearable computing devices.


Assuntos
Hidrogéis , Silicatos , Hidrogéis/química , Condutividade Elétrica , Silicatos/química , Polímeros/química
6.
Int J Mol Sci ; 23(22)2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36430393

RESUMO

The aim of the study was to analyze the chemical-physical properties and bioactivity (apatite-forming ability) of three recently introduced premixed bioceramic root canal sealers containing varied amounts of different calcium silicates (CaSi): a dicalcium and tricalcium silicate (1-10% and 20-30%)-containing sealer with zirconium dioxide and tricalcium aluminate (CERASEAL); a tricalcium silicate (5-15%)-containing sealer with zirconium dioxide, dimethyl sulfoxide and lithium carbonate (AH PLUS BIOCERAMIC) and a dicalcium and tricalcium silicate (10% and 25%)-containing sealer with calcium aluminate, tricalcium aluminate and tantalite (NEOSEALER FLO). An epoxy resin-based sealer (AH PLUS) was used as control. The initial and final setting times, radiopacity, flowability, film thickness, open pore volume, water absorption, solubility, calcium release and alkalizing activity were tested. The nucleation of calcium phosphates and/or apatite after 28 days aging in Hanks balanced salt solution (HBSS) was evaluated by ESEM-EDX, vibrational IR and micro-Raman spectroscopy. The analyses showed for NeoSealer Flo and AH Plus the longest final setting times (1344 ± 60 and 1300 ± 60 min, respectively), while shorter times for AH Plus Bioceramic and Ceraseal (660 ± 60 and 720 ± 60 min, respectively). Radiopacity, flowability and film thickness complied with ISO 6876/12 for all tested materials. A significantly higher open pore volume was observed for NeoSealer Flo, AH Plus Bioceramic and Ceraseal when compared to AH Plus (p < 0.05), significantly higher values were observed for NeoSealer Flo and AH Plus Bioceramic (p < 0.05). Ceraseal and AH Plus revealed the lowest solubility. All CaSi-containing sealers released calcium and alkalized the soaking water. After 28 days immersion in HBSS, ESEM-EDX analyses revealed the formation of a mineral layer that covered the surface of all bioceramic sealers, with a lower detection of radiopacifiers (Zirconium for Ceraseal and AH Plus Bioceramic, Tantalum for NeoSealer Flo) and an increase in calcium, phosphorous and carbon. The calcium phosphate (CaP) layer was more evident on NeoSealer Flo and AH Plus Bioceramic. IR and micro-Raman revealed the formation of calcium carbonate on the surface of all set materials. A thin layer of a CaP phase was detected only on AH Plus Bioceramic and NeoSealer Flo. Ceraseal did not show CaP deposit despite its highest calcium release among all the tested CaSi-containing sealers. In conclusion, CaSi-containing sealers met the required chemical and physical standards and released biologically relevant ions. Slight/limited apatite nucleation was observed in relation to the high carbonation processes.


Assuntos
Materiais Restauradores do Canal Radicular , Materiais Restauradores do Canal Radicular/química , Cálcio/química , Cavidade Pulpar , Silicatos/química , Água/química , Apatitas
7.
Cells ; 11(22)2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36429050

RESUMO

Silicon (Si) is gaining widespread attention due to its prophylactic activity to protect plants under stress conditions. Despite Si's abundance in the earth's crust, most soils do not have enough soluble Si for plants to absorb. In the present study, a silicate-solubilizing bacterium, Enterobacter sp. LR6, was isolated from the rhizospheric soil of rice and subsequently characterized through whole-genome sequencing. The size of the LR6 genome is 5.2 Mb with a GC content of 54.9% and 5182 protein-coding genes. In taxogenomic terms, it is similar to E. hormaechei subsp. xiangfangensis based on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH). LR6 genomic data provided insight into potential genes involved in stress response, secondary metabolite production, and growth promotion. The LR6 genome contains two aquaporins, of which the aquaglyceroporin (GlpF) is responsible for the uptake of metalloids including arsenic (As) and antimony (Sb). The yeast survivability assay confirmed the metalloid transport activity of GlpF. As a biofertilizer, LR6 isolate has a great deal of tolerance to high temperatures (45 °C), salinity (7%), and acidic environments (pH 9). Most importantly, the present study provides an understanding of plant-growth-promoting activity of the silicate-solubilizing bacterium, its adaptation to various stresses, and its uptake of different metalloids including As, Ge, and Si.


Assuntos
Enterobacter , Genômica , Enterobacter/genética , Silicatos , Silício , Plantas/genética , DNA
8.
Molecules ; 27(21)2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36364361

RESUMO

A topological index is a numerical parameter that is derived mathematically from a graph structure. In chemical graph theory, these indices are used to quantify the chemical properties of chemical compounds. We compute the first and second temperature, hyper temperature indices, the sum connectivity temperature index, the product connectivity temperature index, the reciprocal product connectivity temperature index and the F temperature index of a molecular graph silicate network and silicate chain network. Furthermore, a QSPR study of the key topological indices is provided, and it is demonstrated that these topological indices are substantially linked with the physicochemical features of COVID-19 medicines. This theoretical method to find the temperature indices may help chemists and others in the pharmaceutical industry forecast the properties of silicate networks and silicate chain networks before trying.


Assuntos
COVID-19 , Humanos , Temperatura , Silicatos
9.
Shanghai Kou Qiang Yi Xue ; 31(3): 318-321, 2022 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-36204965

RESUMO

PURPOSE: To compare the curative effect of microscopic revascularization and apexification in the treatment of pulp necrosis of permanent teeth. METHODS: Seventy-five cases of pulp necrosis in young permanent teeth were divided into two groups according to different treatment methods. Group A (n=30) underwent revascularization under microscope, while group B (n=45) underwent apexification. The treatment effect and pain improvement of the two groups were compared. The changes of the wall thickness and root canal length of the affected teeth before and after treatment were observed, and the bone-like deposition rate after treatment was recorded. SPSS 23.0 software package was used for statistical analysis. RESULTS: There was no significant difference in the length of root canal between the two groups before treatment (P>0.05); there was no significant difference in the length of root canal in group B before and after treatment (P>0.05); the length of root canal in group A was significantly longer than that in group B 6 months after treatment(P<0.05). There was no significant change in the thickness of root canal wall in group B before and after treatment (P>0.05). The thickness of root canal in group A was significantly higher than that in group A 6 months after treatment (P<0.05). Bone-like deposition rate of group A was significantly higher than that of group B 1 month and 6 months after treatment (P<0.05). The total effective rate of group A and B was 90.00% and 84.44%, the difference was not statistically significant (P>0.05). The cure rate of group A was 70.00%, which was significantly higher than that of group B (48.89%, P<0.05). COCLUSIONS: Microscopic revascularization for pulp necrosis of young permanent teeth can effectively promote root development, lengthen root canal and increase the thickness of canal wall, which is better than apexification.


Assuntos
Apexificação , Materiais Restauradores do Canal Radicular , Apexificação/métodos , Necrose da Polpa Dentária/terapia , Humanos , Óxidos , Tratamento do Canal Radicular/efeitos adversos , Tratamento do Canal Radicular/métodos , Silicatos , Ápice Dentário
10.
Indian J Dent Res ; 33(2): 223-226, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36254966

RESUMO

Introduction: This case report presents the diagnosis and management of extensive internal root resorption (IRR) in a 17-year-old male patient, with a 9-year-old history of trauma. Method: The affected tooth 21 was associated with vertical root fracture (VRF) and incomplete apex closure with a substantial loss of tooth structure, including dentin and cementum. Encouraged by a healthy periodontal condition, the choice was made to use mineral trioxide aggregate (MTA) to reconstruct and reinforce the resorptive defect and the fractured segment. A composite veneer was placed to enhance the aesthetics. Result: A follow-up of the patient after 2 years revealed healing with a resolution of the lesion. Conclusion: This case report highlights the use of MTA as a lone-standing filling material for the treatment of IRR with VRF in a non-vital immature tooth.


Assuntos
Materiais Restauradores do Canal Radicular , Reabsorção da Raiz , Adolescente , Compostos de Alumínio/uso terapêutico , Compostos de Cálcio/uso terapêutico , Criança , Combinação de Medicamentos , Humanos , Masculino , Óxidos/uso terapêutico , Pemetrexede , Materiais Restauradores do Canal Radicular/uso terapêutico , Reabsorção da Raiz/diagnóstico por imagem , Reabsorção da Raiz/terapia , Silicatos/uso terapêutico
11.
Dent Mater ; 38(11): 1763-1776, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36182549

RESUMO

OBJECTIVES: This study aimed to develop and characterize different formulations of porous chitosan scaffolds (SCH) associated with calcium silicate (CaSi) and evaluate their chemotactic and bioactive potential on human dental pulp cells (hDPCs). METHODS: Different concentrations of CaSi suspensions (0.5%, 1.0%, and 2.0%, w/v) were incorporated (1:5; v/v) /or not, into 2% chitosan solution, giving rise to the following groups: SCH (control); SCH+ 0.5CaSi; SCH+ 1.0CaSi; SCH+ 2.0 CaSi. The resulting solutions were submitted to thermally induced phase separation followed by freeze-drying procedures to obtain porous scaffolds. The topography, pH, and calcium release kinetics of the scaffolds were assessed. Next, the study evaluated the influence of these scaffolds on cell migration (MG), viability (VB), proliferation (PL), adhesion and spreading (A&S), and on total protein synthesis (TP), alkaline phosphatase (ALP) activity, mineralized matrix deposition (MMD), and gene expression (GE) of odontogenic differentiation markers (ALP, DSPP, and DMP-1). The data were analyzed with ANOVA complemented with the Tukey post-hoc test (α = 5%). RESULTS: Incorporation of the CaSi suspension into the chitosan scaffold formulation increased pore diameter when compared with control. Increased amounts of CaSi in the CH scaffold resulted in higher pH values and Ca release. In Groups SCH+ 1.0CaSi and SCH+ 2.0CaSi, increased VB, PF, A&S, GE of DSPP/DMP-1 and MMD values were shown. However, Group SCH+ 2.0CaSi was the only formulation capable of enhancing MG and showed the highest increase in TP, MMD, and GE of DMP-1 and DSPP values. SIGNIFICANCE: SCH+ 2.0CaSi formulation had the highest chemotactic and bioactive potential on hDPCs and may be considered a potential biomaterial for pulp-dentin complex regeneration.


Assuntos
Quitosana , Fosfatase Alcalina/metabolismo , Materiais Biocompatíveis/química , Cálcio , Compostos de Cálcio , Diferenciação Celular , Proliferação de Células , Quitosana/farmacologia , Polpa Dentária , Capeamento da Polpa Dentária , Humanos , Porosidade , Silicatos , Engenharia Tecidual , Tecidos Suporte/química
12.
Braz Dent J ; 33(5): 18-25, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36287495

RESUMO

Calcium silicate-based root canal sealers have been developed in powder/liquid or premixed ready-to-use forms. The evaluation of the physico-chemical properties of a prototype powder/liquid MTApex Sealer (Ultradent) in comparison to a ready-to-use material EndoSequence BC Sealer (Brasseler) was performed. The paste/paste epoxy resin-based AH Plus (Dentsply) served as control for comparisons. The sealers were evaluated (n = 6) regarding setting time (in dry and moist environments), flow and radiopacity, following the ISO-6876/2012 standard. Also, the pH was assessed. Material's surface and chemical characterization was evaluated using scanning-electron-microscopy (SEM) and energy-dispersive-spectrometry (EDS). Mixed ANOVA, Shapiro-Wilk, Levene, and post-hoc analysis with Bonferroni correction were performed at a significance level of 5%. MTApex Sealer exhibited the highest flow and EndoSequence BC Sealer had a significantly longer setting time in dry compared to the moist environment; however, for MTApex Sealer and AH Plus no significant changes occurred when additional moisture was provided. All materials exceeded 7 mm Al of radiopacity and showed a decreasing alkalinity over the 21 day-analysis. SEM/EDS evaluation resulted in peaks of calcium, silicon, and the respective radiopacifier. The prototype powder/liquid MTApex Sealer had the highest flow and similar setting time in both dry and moist environments; opposingly, EndoSequence BC Sealer was crucially influenced by external moisture. This suggests that the powder/liquid materials' setting seems to be more predictable.


Assuntos
Resinas Epóxi , Materiais Restauradores do Canal Radicular , Resinas Epóxi/química , Materiais Restauradores do Canal Radicular/química , Pós , Silício , Cálcio , Teste de Materiais , Compostos de Cálcio/química , Silicatos/química
13.
Braz Dent J ; 33(5): 9-17, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36287503

RESUMO

This study assessed the cell viability, cytokine production, and mineralization potential of human dental pulp cells (hDPCs) after exposure to lipopolysaccharide (LPS) and application of calcium silicate-based materials (CSBM). Characterization of the CSBM was performed by infrared spectroscopy (n = 3). Extracts of Bio-C Repair, Biodentine, Cimmo HD, and MTA Repair HP were prepared and diluted (1:1, 1:4, and 1:16). Culture of hDPCs was established and treated or not with 1 µg/mL of LPS from Escherichia coli for 7 days. MTT assay was used to assess cell viability at 24, 48, and 72 h (n = 6). Alkaline phosphatase (ALP) activity was assayed on day 7 (n = 4). Il-10 and TNF-α were quantified by ELISA at 24 h (n = 6). Data were analyzed by ANOVA and Tukey's test (α = 0.05). Cell viability of LPS-activated hPDCs was higher than untreated control in 48 and 72 h (p < 0.05). Differences between non-treated and LPS-activated hPDCs were observed for Biodentine and Cimmo HP (p < 0.05). The CSBM influenced the cell viability (p < 0.05). ALP activity was higher in LPS-activated hDPCs (p < 0.05). No changes in the concentration of TNF-α were observed between groups (p > 0.05). The CSBM increased the Il-10 production (p < 0.05). LPS-activated hDPCs presented increased cell viability and ALP activity. The CSBM showed mild toxicity and was able to enhance the cell viability and mineralization potential of untreated and LPS-activated hDPCs. The CSBM also induced anti-inflammatory mechanisms without compromising pro-inflammatory ones.


Assuntos
Interleucina-10 , Lipopolissacarídeos , Humanos , Lipopolissacarídeos/farmacologia , Polpa Dentária , Fosfatase Alcalina , Fator de Necrose Tumoral alfa , Pemetrexede , Diferenciação Celular , Compostos de Cálcio/farmacologia , Silicatos/farmacologia , Células Cultivadas
14.
Ann Afr Med ; 21(3): 198-203, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36204903

RESUMO

Aim: This study aims to compare the fracture resistance of simulated immature teeth after using different thicknesses of Mineral Trioxide Aggregate (MTA) and Biodentine apical plug. Materials and Methods: Forty human maxillary anterior teeth were selected. Teeth were randomly divided into eight groups of five teeth in each group. Positive control group = 5 teeth; prepared without access cavity preparation. Access cavities of the remaining 35 teeth were prepared, and instrumented with Peeso reamers. Negative control = 5 teeth; filled with calcium hydroxide. Thirty teeth divided into Groups 1 and 2 of MTA (MTA-Angelus, Londrina, Brazil) and Biodentine (Septodant, Saint Maur des Fosses, France) and each group divided into three subgroups: subgroup A - 3 mm apical plug; subgroup B - 6 mm apical plug; and subgroup C: full canal length. The rest of the canals in subgroups A and B were filled with gutta-percha and AH Plus sealer. After the required storage period, all the samples were subjected to fracture testing under universal testing machine and fracture strength was recorded. Data were analyzed using 1-way analysis of variance with the Tukey post hoc test for multiple comparisons. Results: The negative control group showed the lowest fracture resistance compared with the other groups (P < 0.0001). The 6-mm apical plug subgroup of biodentine showed the highest fracture resistance. Conclusion: Within the limitations of this study, MTA and Biodentine can be used as an apical plug instead of root canal filling material to increase the fracture resistance of immature teeth.


Résumé Objectif: Cette étude vise à comparer la résistance à la fracture de dents immatures simulées après utilisation de différentes épaisseurs de trioxyde minéral Agrégat (MTA) et bouchon apical Biodentine. Matériel et Méthodes: Quarante dents antérieures maxillaires humaines ont été sélectionnées. Les dents étaient divisé au hasard en huit groupes de cinq dents dans chaque groupe. Groupe témoin positif = 5 dents; préparé sans préparation de la cavité d'accès. Les cavités d'accès des 35 dents restantes ont été préparées et instrumentées avec des alésoirs Peeso. Contrôle négatif = 5 dents; rempli de calcium hydroxyde. Trente dents réparties en groupes 1 et 2 de MTA (MTA-Angelus, Londrina, Brésil) et Biodentine (Septodant, Saint Maur des Fosses, France) et chaque groupe divisé en trois sous-groupes: sous-groupe A - bouchon apical de 3 mm; sous-groupe B - bouchon apical de 6 mm; et sous-groupe C: longueur totale du canal. Les autres canaux des sous-groupes A et B étaient remplis de gutta-percha et de scellant AH Plus. Après le stockage requis période, tous les échantillons ont été soumis à des essais de fracture sous une machine d'essai universelle et la résistance à la rupture a été enregistrée. Les données étaient analysé à l'aide d'une analyse de variance unidirectionnelle avec le test post hoc de Tukey pour des comparaisons multiples. Résultats: le groupe témoin négatif a montré la résistance à la fracture la plus faible par rapport aux autres groupes (p <0,0001). Le sous-groupe du bouchon apical de 6 mm de la biodentine a montré le plus résistance à la fracture. Conclusion: Dans les limites de cette étude, le MTA et la Biodentine peuvent être utilisés comme bouchon apical au lieu de canal radiculaire matériau de remplissage pour augmenter la résistance à la fracture des dents immatures. Mots-clés: bouchon apical, biodentine, résistance à la fracture, agrégat de trioxyde minéral.


Assuntos
Materiais Restauradores do Canal Radicular , Fraturas dos Dentes , Compostos de Alumínio , Compostos de Cálcio , Hidróxido de Cálcio , Combinação de Medicamentos , Guta-Percha , Humanos , Óxidos , Pemetrexede , Silicatos
16.
Sci Rep ; 12(1): 16470, 2022 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-36183044

RESUMO

The search for Terrestrial Analogues is essential for the development of future permanent or semi-permanent lunar bases. Terrestrial Analogues are zones where it is possible to probe not only scientific instruments, but also other astronaut capabilities in an environment that is similar to the geological context, geomorphology, mineralogy, geochemistry, etc. that we can find on Mars, the Moon and even asteroids. This work has focused on a multi-analytical characterization of Peñas de Tao geosite basalts in Lanzarote (Canary Islands, Spain). This characterization starts from a field campaign in which 3000 g of basalt rocks were selected. Subsequently, they were analysed by different techniques to determine their composition at a mineralogical and geochemical level, and the results were compared with data from other lunar simulants and from the Apollo 14 mission. After that, a set of petrophysical tests was carried out in order to determine its physical properties and evaluate its capacity as an analogous material for use in situ as a resource for further geological and astrobiological (future lunar habitability) essays.


Assuntos
Lua , Solo , Silicatos , Solo/química , Espanha
17.
Nat Commun ; 13(1): 5965, 2022 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-36216953

RESUMO

The western maria of lunar near-side are widely covered with late-stage mare basalts. Due to the lack of returned samples, the mineralogy of the late-stage basalts was previously speculated as having high abundance of olivine based on remote sensing observation. However, here we show that Chang'E-5 (CE-5) lunar soil samples, the ground truth from past unsampled lunar late-stage mare region, give a different interpretation. Our laboratory spectroscopic and X-ray diffraction (XRD) analyses of the CE-5 soil samples demonstrate that their special spectral signatures are representative of iron-rich high-Ca pyroxene rather than olivine. Considering the spectral and compositional similarities between CE-5 soil samples and lunar late-stage basalts, the mineralogy and petrology of CE-5 samples may be able to be generalized to entire lunar late-stage basalts. Our study would provide a constraint on the thermal evolution of the Moon, especially the young lunar volcanism.


Assuntos
Ferro , Silicatos , Animais , Feminino , Cavalos , Compostos de Ferro , Compostos de Magnésio , Solo/química
18.
PLoS One ; 17(10): e0276260, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36269773

RESUMO

This study demonstrates the vertical and horizontal distribution of nutrients and the seasonal response of nutrients to upwelling in the Arabian Gulf and the Sea of Oman. Thus, monthly data on nitrate, phosphate, and silicate are obtained from the World Ocean Atlas 2018 (WOA), as well as estimates of coastal and curl driven upwelling in both regions. The results of the study indicate that the Sea of Oman's surface and deep waters contained higher concentrations of nutrients than the Arabian Gulf by 80%. In addition, both regions have exhibited a general increase in the vertical distribution of nutrients as the depth increases. Among the aforementioned nutrients, nitrate is found to be a more limiting nutrient for phytoplankton growth than phosphate as the nitrate-to-phosphate ratios (N:P) in surface waters are lower (≤ 4.6:1) than the Redfield ratio (16:1). As for the upwelling, curl-driven upwelling accounts for more than half of the total upwelling in both regions, and both play an important role in nutrient transport. Thus, nutrients are upwelled from the subsurface to the mixed layer at a rate of 50% in the Oman Sea from 140 m to 20 m during the summer and to 40 m during the winter. Similarly, the Arabian Gulf shows 50% transport for nitrates, but 32% for phosphates, from 20 m to 5-10 m. However, due to the abundance of diatoms at the surface of the Arabian Gulf, the surface silicate content is 30% higher than that of the deeper waters.


Assuntos
Nitratos , Fitoplâncton , Omã , Fitoplâncton/fisiologia , Estações do Ano , Nutrientes , Fosfatos , Silicatos , Água do Mar
19.
Environ Sci Technol ; 56(22): 15261-15272, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36269897

RESUMO

Enhanced weathering (EW) is one of the most promising negative emissions technologies urgently needed to limit global warming to at least below 2 °C, a goal recently reaffirmed at the UN Global Climate Change conference (i.e., COP26). EW relies on the accelerated dissolution of crushed silicate rocks applied to soils and is considered a sustainable solution requiring limited technology. While EW has a high theoretical potential of sequestering CO2, research is still needed to provide accurate estimates of carbon (C) sequestration when applying different silicate materials across distinct climates and major soil types in combination with a variety of plants. Here we elaborate on fundamental advances that must be addressed before EW can be extensively adopted. These include identifying the most suitable environmental conditions, improving estimates of field dissolution rates and efficacy of CO2 removal, and identifying alternative sources of silicate materials to meet future EW demands. We conclude with considerations on the necessity of integrated modeling-experimental approaches to better coordinate future field experiments and measurements of CO2 removal, as well as on the importance of seamlessly coordinating EW with cropland and forest management.


Assuntos
Dióxido de Carbono , Tempo (Meteorologia) , Dióxido de Carbono/análise , Mudança Climática , Solo , Silicatos , Sequestro de Carbono
20.
Eur Endod J ; 7(3): 203-209, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36217642

RESUMO

OBJECTIVE: To compare, in vitro, the bioceramic materials (MTA and BC RRM-fast set putty) capacity to prevent microleakage of Enterococcus faecalis over time. METHODS: An experimental design was made with forty extracted human teeth, coronally cut, and prepared to be placed in a leakage system under sterile conditions. They were randomly divided into two experimental groups: thirty teeth (fifteen for each of retrograde filling material MTA and BC RRM-fast set putty) and a control group: ten teeth (five positive control, five negative control). The 3 mm root-ends were submerged in a brain-heart infusion broth with a red phenol indicator. The coronal access of each sample was inoculated with E. faecalis every seven days to maintain bacterial viability. The lower chamber was evaluated daily for 30 days to observe the turbidity of the culture medium and establish the presence and day of the filtration. Calculation of the colony-forming units (CFU) was performed for each leaked sample. Fisher's Exact Test was used to verify the association between the presence or absence of leakage of the samples by type of bioceramic material used and the Mann-Whitney U test to verify the existence of a difference between the average of CFU by type of bioceramic material used. The significance level used was α=0.05 and a 95% confidence level, as a decision rule for rejecting the null hypothesis. RESULTS: Of the total samples prepared for each group, leakage was found in 60.0% (9/15) of the MTA group and 40.0% (6/15) of the BC RRM-fast set putty group. All positive controls filtered on the first day of evaluation, while 20% (1/5) of the negative control leaked in the second week. There was no significant difference in leakege between the two groups, nor concerning the bacterial count (P=0.101) and the type of cement used (P=1.000). CONCLUSION: BC RRM-fast set putty was comparable to MTA in resisting bacterial microleakage during the observation time.


Assuntos
Materiais Restauradores do Canal Radicular , Compostos de Alumínio , Compostos de Cálcio , Humanos , Óxidos , Pemetrexede , Fenóis , Silicatos
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