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1.
Chemosphere ; 260: 127668, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758779

RESUMO

A series of pollutants can be removed from soil using a Fenton-like oxidation and biological treatment. As a natural mineral, tourmaline has been used for as a material of Fenton-like reaction. In the present study, the risks of remediation technology tourmaline catalyzed Fenton-like reaction (TCFR) combined with Phanerochaete chrysosporium (TCFR + P) were assessed through measuring soil properties, physiological response of plant, and PBDEs migration from soil to plant. Batch pot experiments showed that the silicon contents, specific surface area and soil pore size of soil in TCFR and 5%TCFR + P groups increased obviously. TCFR and TCFR + P treatments promoted the lettuce growth compared to control. Moreover, chlorophyll content of lettuce in 2%TCFR + P and 5%TCFR + P group increased by 46.74% and 44.57% than that in the CK, respectively. The treatment of 2%TCFR decreased the total concentration of PBDEs in rhizosphere soil and non-rhizosphere soil by 52.0.2% and 64.17%, respectively, after 60 days compared to the soil of CK, and did not prompt the uptake of lower-brominated PBDEs by lettuce. TCFR and TCFR + P can alter the migration of BDE isomers from soil to plant, the ratio of BDE99/BDE100 in lettuce shoots decreased slightly. BDE-99/BDE-100 ratios in the shoots were lower than those in the roots, while BDE153/BDE154 ratios were higher than 1.0 and ratios in shoots were higher than those in roots. Therefore, our findings illustrated that the TCFR could be applied to remediate the agricultural soil, considering the appropriate doses of tourmaline.


Assuntos
Biodegradação Ambiental , Éteres Difenil Halogenados/metabolismo , Silicatos/química , Poluentes do Solo/metabolismo , Catálise , Éteres Difenil Halogenados/análise , Alface , Minerais , Phanerochaete , Raízes de Plantas/química , Bifenil Polibromatos , Rizosfera , Solo , Poluentes do Solo/análise
2.
Niger J Clin Pract ; 23(8): 1068-1072, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32788483

RESUMO

Aims: The aim of this study was to compare the influence of operators on the microhardness and compressive strength of mineral trioxide aggregate (MTA). Materials and Methods: Forty dental specialists were asked to prepare a series of MTA samples. The tested material was ProRoot MTA (DentsplyMaillefer, Switzerland). Each participant prepared one sample to a consistency they considered acceptable for use in practice (improvised group) and another one according to the manufacturer's recommended water-to-powder (WP) ratio (pre-weighed group). The samples were incubated at 37°C and 95% humidity for 4 days. Parameters evaluated in this study were microhardness and compressive strength. Results: Operators mixed MTA samples with varying WP ratios. However, there was no significant difference between the microhardness and compressive strength values of MTA samples between the improvised, the pre-weighed and the control groups. MTA was mixed in a thicker consistency than the manufacturers recommended ratio (0.33) by 62.5% of the operators. Conclusion: According to the results of this study, even though the WP ratios that were utilized in the clinical setting vary, microhardness and compressive strength values of MTA was not significantly affected.


Assuntos
Compostos de Alumínio/química , Compostos de Cálcio/química , Força Compressiva , Teste de Materiais/métodos , Óxidos/química , Materiais Restauradores do Canal Radicular , Silicatos/química , Estudos de Casos e Controles , Combinação de Medicamentos , Dureza , Humanos , Água
3.
Nature ; 583(7815): 242-248, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32641817

RESUMO

Enhanced silicate rock weathering (ERW), deployable with croplands, has potential use for atmospheric carbon dioxide (CO2) removal (CDR), which is now necessary to mitigate anthropogenic climate change1. ERW also has possible co-benefits for improved food and soil security, and reduced ocean acidification2-4. Here we use an integrated performance modelling approach to make an initial techno-economic assessment for 2050, quantifying how CDR potential and costs vary among nations in relation to business-as-usual energy policies and policies consistent with limiting future warming to 2 degrees Celsius5. China, India, the USA and Brazil have great potential to help achieve average global CDR goals of 0.5 to 2 gigatonnes of carbon dioxide (CO2) per year with extraction costs of approximately US$80-180 per tonne of CO2. These goals and costs are robust, regardless of future energy policies. Deployment within existing croplands offers opportunities to align agriculture and climate policy. However, success will depend upon overcoming political and social inertia to develop regulatory and incentive frameworks. We discuss the challenges and opportunities of ERW deployment, including the potential for excess industrial silicate materials (basalt mine overburden, concrete, and iron and steel slag) to obviate the need for new mining, as well as uncertainties in soil weathering rates and land-ocean transfer of weathered products.


Assuntos
Agricultura , Dióxido de Carbono/isolamento & purificação , Produtos Agrícolas , Sedimentos Geológicos/química , Aquecimento Global/prevenção & controle , Objetivos , Silicatos/química , Atmosfera/química , Brasil , China , Política Ambiental/economia , Política Ambiental/legislação & jurisprudência , Aquecimento Global/economia , Índia , Ferro/isolamento & purificação , Mineração , Política , Probabilidade , Silicatos/isolamento & purificação , Aço/isolamento & purificação , Temperatura , Fatores de Tempo , Estados Unidos
4.
Proc Natl Acad Sci U S A ; 117(25): 14299-14305, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32513701

RESUMO

The Lower Cretaceous Huajiying Formation of the Sichakou Basin in northern Hebei Province, northern China contains key vertebrate taxa of the early Jehol Biota, e.g., Protopteryx fengningensis, Archaeornithura meemannae, Peipiaosteus fengningensis, and Eoconfuciusornis zhengi This formation arguably documents the second-oldest bird-bearing horizon, producing the oldest fossil records of the two major Mesozoic avian groups Enantiornithes and Ornithuromorpha. Hence, precisely determining the depositional ages of the Huajiying Formation would advance our understanding of the evolutionary history of the Jehol Biota. Here we present secondary ion mass spectrometry (SIMS) U-Pb zircon analysis results of eight interbedded tuff/tuffaceous sandstone samples from the Huajiying Formation. Our findings, combined with previous radiometric dates, suggest that the oldest enantiornithine and ornithuromorph birds in the Jehol Biota are ∼129-131 Ma, and that the Jehol Biota most likely first appeared at ∼135 Ma. This expands the biota's temporal distribution from late Valanginian to middle Aptian with a time span of about 15 My.


Assuntos
Biota , Aves/classificação , Chumbo/química , Silicatos/química , Zircônio/química , Animais , Evolução Biológica , China , Fósseis , Geologia , Filogenia , Espectrometria de Massa de Íon Secundário
5.
Int J Nanomedicine ; 15: 3921-3936, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32581537

RESUMO

Background: Mesoporous calcium-silicate nanoparticles (MCSNs) have good prospects in the medical field due to their great physicochemical characteristics, antibacterial activity and drug delivery capacity. This study was to analyze the antibiofilm activity and mechanisms of silver (Ag) and zinc (Zn) incorporated MCSNs (Ag/Zn-MCSNs) with different percentages of Ag and Zn. Methods: Ag/Zn(1:9, molar ratio)-MCSNs and Ag/Zn(9:1, molar ratio)-MCSNs were prepared and characterized. Endocytosis of nanoparticles by Enterococcus faecalis (E. faecalis) treated with Ag/Zn-MCSNs was observed using TEM to explore the antibacterial mechanisms. The antibiofilm activity of Ag/Zn-MCSNs with different ratios of Ag and Zn was tested by E. faecalis biofilm model in human roots. The human roots pretreated by different Ag/Zn-MCSNs were cultured with E. faecalis. Then, SEM and CLSM were used to observe the survival of E. faecalis on the root canal wall. Cytotoxicity of the nanoparticles was tested by CCK8 kits. Results: The Ag/Zn-MCSNs release Ag+ and destroy the cell membranes to kill bacteria. The MCSNs containing Ag showed antibacterial activity against E. faecalis biofilms in different degrees, and they can adhere to dentin surfaces to get a continuous antibacterial effect. However, MTA, MCSNs and Zn-MCSNs could not disrupt the bacterial biofilms obviously. MCSNs, Ag/Zn(1:1, molar ratio)-MCSNs and Ag/Zn(1:9)-MCSNs showed no obvious cytotoxicity, while Ag-MCSNs and Ag/Zn(9:1)-MCSNs showed cytotoxicity. Zn-MCSNs can slightly promote cell proliferation. Conclusion: Ag/Zn-MCSNs have good antibiofilm activity. They might achieve an appropriate balance between the antibacterial activity and cytotoxicity by adjusting the ratio of Ag and Zn. Ag/Zn-MCSNs are expected to be a new type of root canal disinfectant or sealer for root canal treatment.


Assuntos
Antibacterianos/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Nanopartículas/química , Prata/química , Zinco/química , Animais , Antibacterianos/química , Biofilmes/efeitos dos fármacos , Compostos de Cálcio/química , Cavidade Pulpar/microbiologia , Dentina/efeitos dos fármacos , Endocitose/efeitos dos fármacos , Enterococcus faecalis/fisiologia , Infecções por Bactérias Gram-Positivas/prevenção & controle , Humanos , Camundongos , Osteoblastos/efeitos dos fármacos , Porosidade , Silicatos/química , Prata/farmacologia , Zinco/farmacologia
6.
Chemosphere ; 256: 127043, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32445999

RESUMO

Electrolytic manganese residue (EMR) is characterized by high silicon content, and thus, is an important silicon source. While considerable research has been conducted on bioleaching EMR for silicon recovery, sufficient information is not available on the impact of specific silicate mineral structures in EMR on silicon bioleaching. In the present study, the mineral composition of EMR was determined firstly, and then the leaching effect of Paenibacillus mucilaginosus on these different silicate minerals were investigated by shake flask experiments. Results showed that the silicon in EMR was mainly composed of quartz, sericite, muscovite, biotite, olivine and rhodonite; Paenibacillus mucilaginosus had a significantly different weathering and decomposition effects on different silicate minerals. Among them, sericite, muscovite and biotite with layered structure had the most obvious silicon leaching effect, followed by rhodonite with island structure, while silicon leaching from olivine with chained structure and quartz with frame structure was much more difficult. One can roughly judge the adaptability of bioleaching of silicon in EMR using Paenibacillus mucilaginosus if the main form of silicate minerals in EMR is determined.


Assuntos
Manganês/metabolismo , Paenibacillus/metabolismo , Silício/química , Silicatos de Alumínio , Eletrólitos , Compostos Ferrosos , Íons , Compostos de Ferro , Compostos de Magnésio , Minerais , Silicatos/química , Dióxido de Silício
7.
Phys Med Biol ; 65(13): 135006, 2020 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-32325449

RESUMO

A practical wearable brain PET scanner capable of dynamic neuroimaging during free bodily movement will enable potential breakthrough basic neuroscience studies and help develop imaging-based neurological diagnoses and treatments. Weight, brain coverage, and sensitivity are three fundamental technical obstacles in the development of Fully Wearable High-Performance (FWHP) brain PET scanners. The purpose of this study is to investigate the feasibility of building a FWHP brain PET using a limited volume of lutetium-yttrium oxyorthosilicate (LYSO) scintillator crystals. Six scanners, consisted of the same volume (2.66 kg) of LYSO scintillators with combinations of 2 different crystal pitches (3 mm and 1.5 mm) and 3 different crystal lengths (20 mm, 10 mm, and 5 mm), were simulated. The performances of the six scanners were assessed and compared with Siemen's HRRT brain PET and mCT whole-body PET, in terms of aperture, axial field of views (AFOV), sensitivity, spatial resolution, count rates, and image noise property. The time-of-flight (TOF) information was included in the image reconstruction to improve the effective sensitivity. The effects of the TOF was assessed by scanning a Jaszczak phantom and reconstructing images with the maximum likelihood expectation maximization (MLEM) algorithm with different timing settings (non-TOF, 500 ps, 200 ps, 100 ps and 50 ps Coincidence Time Resolution, CTR). The signal-noise ratio (SNR) of the images were assessed and compared with those of the HRRT scanner and mCT scanner. The results show that it is possible to construct a FWHP brain PET with better spatial resolution than the dedicated HRRT brain PET, comparable effective sensitivity (with 50 ∼ 100 ps CTR), and whole-brain coverage (23.7 cm inner diameter and 13.4 cm axial field of view) using 2.66 kg of LYSO.


Assuntos
Encéfalo/diagnóstico por imagem , Desenho de Equipamento , Neuroimagem/instrumentação , Tomografia por Emissão de Pósitrons/instrumentação , Dispositivos Eletrônicos Vestíveis , Algoritmos , Processamento de Imagem Assistida por Computador , Lutécio/química , Imagens de Fantasmas , Contagem de Cintilação , Silicatos/química , Ítrio/química
8.
Nat Commun ; 11(1): 1735, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32269223

RESUMO

The therapeutic effect of reactive oxygen species (ROS)-involved cancer therapies is significantly limited by shortage of oxy-substrates, such as hypoxia in photodynamic therapy (PDT) and insufficient hydrogen peroxide (H2O2) in chemodynamic therapy (CDT). Here, we report a H2O2/O2 self-supplying nanoagent, (MSNs@CaO2-ICG)@LA, which consists of manganese silicate (MSN)-supported calcium peroxide (CaO2) and indocyanine green (ICG) with further surface modification of phase-change material lauric acid (LA). Under laser irradiation, ICG simultaneously generates singlet oxygen and emits heat to melt the LA. The exposed CaO2 reacts with water to produce O2 and H2O2 for hypoxia-relieved ICG-mediated PDT and H2O2-supplying MSN-based CDT, acting as an open source strategy for ROS production. Additionally, the MSNs-induced glutathione depletion protects ROS from scavenging, termed reduce expenditure. This open source and reduce expenditure strategy is effective in inhibiting tumor growth both in vitro and in vivo, and significantly improves ROS generation efficiency from multi-level for ROS-involved cancer therapies.


Assuntos
Tratamento Farmacológico , Fotoquimioterapia , Espécies Reativas de Oxigênio/metabolismo , Animais , Circulação Sanguínea , Compostos de Cálcio/química , Linhagem Celular Tumoral , Sobrevivência Celular , Sinergismo Farmacológico , Feminino , Humanos , Peróxido de Hidrogênio/metabolismo , Verde de Indocianina/química , Ácidos Láuricos/sangue , Ácidos Láuricos/química , Imagem por Ressonância Magnética , Manganês/química , Camundongos Endogâmicos BALB C , Nanopartículas/química , Nanopartículas/ultraestrutura , Óxidos/química , Silicatos/química , Superóxidos/metabolismo , Distribuição Tecidual
9.
An Acad Bras Cienc ; 92(2): e20180981, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32187251

RESUMO

The Paraná-Etendeka Magmatic Province is associated with the distensive tectonics that caused the rupture of the Gondwana continent during the Lower Cretaceous and generated an intense volcanism that covers South America and the NW portion of Namibia in Africa. In Brazil, this volcanic sequence is named Serra Geral Group and predominantly consists of basalts and subordinated silicic rocks. The goal of this study is to characterize the geomorphological features observed in the Aparados da Serra region, southern Brazil, and to evaluate the relationship between these structures and the primary silicic volcanic structures. The geomorphological features were first identified using remote sensing and then correlated with flow structures observed in the field, as well as petrographic and geochemical data. AMS data were used to determine magnetic patterns and the direction of magmatic flow of the rocks. Despite the low degree of anisotropy, clear patterns of lineation and foliation were identified in the studied rocks. Our data shows that Units I and II correspond to silicic lava flows linked to effusive fissure eruptions, presenting a dome morphology caused by differential erosion. Unit III rocks may correspond to true volcanic domes, whereas the Unit IV corresponds to the effusive feeder structures.


Assuntos
Silicatos/química , Erupções Vulcânicas/análise , Brasil
10.
Inorg Chem ; 59(5): 2969-2977, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32049497

RESUMO

X-ray radio-luminescence materials have potential application in radiotherapy (RT) and biomedical imaging. Considering that lutecium ions (Lu3+) with high atomic number (Z) have high X-ray attenuation coefficients, Ce3+-doped A-type Lu2SiO5@SiO2 (A-LSO:Ce3+@SiO2) core-shell nanospheres with size in the range of 200-250 nm were prepared through coprecipitation method. The growth mechanism of A-LSO:Ce3+@SiO2 core-shell nanospheres was investigated through determining the phase transition and morphology evolution by XRD, FT-IR, and TEM. The emission spectra, decay profile, and X-ray excited luminescence spectra (XEL) of the obtained samples were collected. The results show that a new type of lutecium silicate core-shell nanospheres A-LSO:Ce3+@SiO2 can be fabricated and exhibit efficient radio-luminescence under X-ray radiation, which has potential application in the diagnosis and therapy of cancer.


Assuntos
Luminescência , Lutécio/química , Nanosferas/química , Silicatos/química , Medições Luminescentes , Teste de Materiais , Tamanho da Partícula , Silicatos/síntese química , Propriedades de Superfície
11.
Mol Biotechnol ; 62(3): 192-199, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32016781

RESUMO

The purpose of this study was to construct a biomimetic urethral repair substitute. The nano-Laponite/polylactic acid-glycolic acid copolymer (PLGA) fiber scaffolds were produced to replicate the natural human urethra tissue microenvironment. PLGA (molar ratio 50:50) and Laponite were used in this study as raw materials. The nano-Laponite/PLGA scaffolds were fabricated via electrospinning technology. After preparing the material, the microstructural and mechanical properties of the nano-Laponite/PLGA scaffold were tested via scanning electron microscopy and electronic universal testing. The effects of different amounts of Laponite on the degradation of the nano-Laponite/PLGA scaffold were studied. Human umbilical vein endothelial cells (HUVECs) were co-cultured with PLGA and nano-Laponite/PLGA scaffolds for 24, 48, or 72 h. Scanning electron microscopy results illustrated that the microstructure of the scaffold fabricated by electrospinning was similar to that of the natural extracellular matrix. When the electrospinning liquid contained 10% Laponite, the nano-Laponite/PLGA stress-strain curve illustrated that the scaffold has strong elastic deformation ability. HUVECs exhibited good growth on the nano-Laponite/PLGA scaffold. When the scaffold contained 1% Laponite, the cell proliferation rate in the CCK-8 test was significantly better than that for the other three materials, displaying good cell culture characteristics. The 1% nano-Laponite/PLGA composite scaffold can be used as a suitable urethral repair material, but its performance requires further development and research.


Assuntos
Células Endoteliais da Veia Umbilical Humana/metabolismo , Nanocompostos/química , Poliésteres/química , Silicatos/química , Engenharia Tecidual , Tecidos Suporte/química , Uretra/metabolismo , Células Endoteliais da Veia Umbilical Humana/citologia , Humanos , Uretra/citologia
12.
BMC Oral Health ; 20(1): 57, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-32070302

RESUMO

BACKGROUND: Intracanal medicaments can be used in various endodontic conditions including multiple visit endodontics after trauma or in regenerative endodontics. These medicaments should be removed from the root canal before the placement of the filling or repair material. The aim of the present study was to evaluate the effect of prior calcium hydroxide (Ca(OH)2) and modified triple antibiotic paste (mTAP) placement on the push-out bond strength of TotalFill BC fast set putty (BC fast set putty) to root dentin when compared to mineral trioxide aggregate (MTA). METHODS: The root canals of 45 extracted mandibular premolars were prepared to a standardized internal diameter (1.5 mm). The specimens were randomly assigned to 3 groups according to the intracanal medicament used: mTAP (a mixture of metronidazole, ciprofloxacin, and cefaclor), Ca(OH)2, and no intracanal medicament. After 1 week, the medicaments were removed, and the middle third of the roots were cut into two transverse sections (2.0 ± 0.05) (n = 90 slices). Thereafter, the specimens were divided into two subgroups (n = 45 each): MTA or BC putty. After 1 week, the push-out test was performed and failure mode was evaluated. The data were statistically analyzed using two-way ANOVA and Tukey's post hoc. RESULTS: The application of the intracanal medicament did not significantly affect the bond strength of BC putty (p > .05). For MTA, the prior application of Ca(OH)2 or mTAP significantly decreased the dislocation resistance (p < .05). Specimens in the MTA subgroups showed an almost equal number of cohesive and mixed types of failure while the majority of the specimens in the BC putty subgroups revealed the cohesive type. CONCLUSIONS: Ca(OH)2 and mTAP promoted lower bond strength of MTA to root dentin compared to the control group. However, the BC fast set putty bond strength to dentin was not affected by prior medication with Ca(OH)2 or mTAP.


Assuntos
Antibacterianos/farmacologia , Compostos de Cálcio/química , Hidróxido de Cálcio/química , Colagem Dentária , Endodontia/métodos , Materiais Restauradores do Canal Radicular/química , Irrigantes do Canal Radicular/química , Silicatos/química , Cálcio , Compostos de Cálcio/farmacologia , Cefaclor , Ciprofloxacino , Humanos , Metronidazol , Silicatos/farmacologia
13.
BMC Oral Health ; 20(1): 37, 2020 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-32013975

RESUMO

BACKGROUND: The present study compares the apical microleakage of three different root-end filling materials in which the retrograde cavity is prepared by two different burs. METHODS: Eighty extracted single rooted maxillary and mandibular premolars were taken. Root canal treatment was completed. Apical 3 mm of all the teeth were resected with diamond disk. The tooth were divided into four groups with two subgroups for each group containing 10 tooth (N = 10) as: Group IA (Negative Control and IB (Positive Control); Group IIA and IIB: Prepared with round carbide bur and round diamond bur respectively, filled with GIC; Group IIIA and IIIB: Prepared with round carbide bur and round diamond bur respectively, filled with MTA; Group IVA and IVB: Prepared with round carbide bur and round diamond bur, filled with Biodentine. After applying two coats of nail varnish leaving apical 3 mm (except for negative control group) all teeth were immersed in 2% methylene blue for 3 days and again in 65% nitric acid for next 3 days for extraction of dye. The obtained solution was then transferred to eppendorf tube and centrifuged in microcentrifuges at 14,000 revolution per minutes (RPM) for 5 min. Optical density or absorbance of the supernatant solution was measured with UV spectrophotometer at 550 nm. RESULTS: The absorbance of the supernatant solution after dye extraction is decreasing in the order of positive control> GIC > MTA > Biodentine> negative control group. The significant difference was observed between GIC and MTA (p = 0.0001) and GIC and Biodentine (p = 0.0001) with two different burs but statistically non-significant difference was observed between MTA and Biodentine with Carbide bur (p = 0.127) and Diamond bur (p = 0.496) respectively. CONCLUSIONS: Within the limitations of the present study, it can be concluded that Biodentine and MTA showed less microleakage as compared to GIC. There is no significant difference between mean microleakage of MTA and Biodentine. However, the mean OD of the Biodentine was least of all evaluated materials. Preparation of the root-end using round carbide bur as well as round diamond burs showed comparable microleakage for all three filling materials.


Assuntos
Compostos de Alumínio/farmacologia , Apicectomia/métodos , Compostos de Cálcio/farmacologia , Cimentos Dentários/química , Infiltração Dentária/prevenção & controle , Óxidos/química , Materiais Restauradores do Canal Radicular/farmacologia , Silicatos/farmacologia , Ápice Dentário/efeitos dos fármacos , Compostos de Alumínio/química , Compostos de Cálcio/química , Infiltração Dentária/diagnóstico , Combinação de Medicamentos , Humanos , Pemetrexede , Materiais Restauradores do Canal Radicular/química , Silicatos/química , Resultado do Tratamento
14.
Mater Sci Eng C Mater Biol Appl ; 108: 110431, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31923972

RESUMO

We successfully synthesized a strontium-doped tricalcium silicate (SrxCa3-xSiO5, Sr = 0 to 2 mol%) bone cement using the sol-gel process. The material properties including crystallinity, setting time, mechanical strength, and hydration products were characterized. Release of ions and pH values of simulated body fluid soaked with the bone cement were measured. In vitro biocompatibility of different concentrations of the material was evaluated by the viability of L929 cells. The setting times of as-prepared slurries were all <70 min. Doping with 0.5 mol% Sr reduced the final setting time by 20 min. After 14 days curing, 0.25 mol% Sr-doped SrxCa3-xSiO5 possessed the highest compressive strength of 45 MPa among all the Sr-doped groups with no statistical difference to Ca3SiO5. The bioactivity of the materials was confirmed with the formation of an apatite layer on the surface of the materials after immersion in simulated body fluid. In addition, the proliferation of L929 cells exposed to 1 mol% Sr was significantly promoted as compared to no Sr doping. SrxCa3-xSiO5 is a novel and advanced material that has the potential to serve as a bone cement in bone restoration with appropriate mechanical strength and favorable biocompatibility.


Assuntos
Cimentos para Ossos , Compostos de Cálcio , Proliferação de Células/efeitos dos fármacos , Teste de Materiais , Silicatos , Estrôncio , Animais , Cimentos para Ossos/síntese química , Cimentos para Ossos/química , Cimentos para Ossos/farmacologia , Compostos de Cálcio/síntese química , Compostos de Cálcio/química , Compostos de Cálcio/farmacologia , Linhagem Celular , Camundongos , Transição de Fase , Silicatos/síntese química , Silicatos/química , Silicatos/farmacologia , Estrôncio/química , Estrôncio/farmacologia
15.
Rev. bras. odontol ; 77(1): 1-5, jan. 2020.
Artigo em Inglês | LILACS | ID: biblio-1103252

RESUMO

Objetivo: comparar a capacidade de adesão do cimento biocerâmico EndoSequence BC e do cimento resinoso AH Plus através de uma revisão integrativa. Material e Métodos: os bancos de dados online Medline/PubMed, Scopus, Web of Science e BVS foram utilizados para a revisão da literatura. Os critérios de elegibilidade incluíram artigos disponíveis na íntegra nas bases de dados pesquisadas, em inglês, e o conteúdo referente à adesão do cimento Endosequence BC sealer em comparação ao AH Plus. Resultados: foram encontrados 45 artigos. Após a remoção duplicada, 22 artigos foram selecionados. Após a leitura dos resumos, textos completos e aplicação dos critérios de inclusão, foram incluídos no total oito artigos. Em relação à capacidade de adesão dos cimentos testados, o AH Plus apresentou melhor adesão do que o cimento BC sealer em três artigos e menor adesão em dois artigos. Força de adesão semelhante foi observada entre os grupos em três estudos. Conclusões: com base nos estudos incluídos, o AH Plus apresenta maior resistência de união quando comparado ao BC Sealer


Aim: To compare the adhesion capacity of the bioceramic EndoSequence BC sealer and the AH Plus sealer through an integrative review. Methodology: The Medline/PubMed, Scopus, Web of Science and VHL online databases were used for the literature review. Eligibility criteria comprised articles available in full on the researched databases, in English, and content addressing Endosequence BC sealer adhesion compared to AH Plus sealer. Results: A total of 45 articles were found. After duplicate removal, 22 articles were selected. After reading the abstracts, full texts and applying the inclusion criteria, eight articles in total were included in the present study. Concerning the adhesion capacity of the tested cements, the AH Plus was reported as presenting better adhesion than the BC sealer in three articles, and less adhesion in two articles. Similar adherence strength was observed between groups in three studies. Conclusions: Based on the included studies, the AH Plus displays greater bond strength when compared to the BC Sealer.


Assuntos
Materiais Restauradores do Canal Radicular , Cimentos de Resina , Cimentos Dentários , Cavidade Pulpar , Endodontia , Silicatos/química
16.
J Colloid Interface Sci ; 564: 155-169, 2020 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-31911221

RESUMO

Hemostatic adhesive hydrogels as sealants for surgical operations are one of the focus of the researches in the field of injectable materials. Herein, we evaluated the potential application of a mechanically robust nanocomposite hydrogel with significant adhesion strength and shorter blood clotting time. This hydrogel was composed of thiolated gelatin (Gel-SH) and gelatin methacrylate (GelMA) as the main matrix to support cell viability and proliferation, while polydopamine functionalized Laponite® (PD-LAP) were introduced to the structure to improve the mechanical properties, adhesion strength, and blood clotting. This hydrogel formed via Michael reaction between Gel-SH and GelMA, and covalent interaction between PD-LAP and hydrogel. Results revealed that presence of PD-LAP significantly controlled the swelling ratio, biodegradability, and mechanical properties of nanocomposite hydrogels. Tensile and compressive strength of nanocomposite hydrogels were measured in the range of 22-84 kPa and 54-153 kPa, respectively. Furthermore, nanocomposite hydrogels revealed excellent recovery ability, strong tissue adhesiveness and significantly less blood clotting time than Gel-SH/GelMA hydrogel (2.25 min). In the culture with L929 fibroblasts cells, viability more than 97% and high proliferation after 5 days of culture was estimated. The simplicity, low-cost, tunable mechanical properties, short blood clotting time, and cytocompatibility of the hydrogels composed of Gel-SH, GelMA, and PD-LAP highlight its potential as hemostat sealants.


Assuntos
Materiais Biocompatíveis , Gelatina , Hidrogéis , Metacrilatos , Nanocompostos/química , Silicatos , Adesivos Teciduais , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Linhagem Celular , Gelatina/química , Gelatina/farmacologia , Humanos , Hidrogéis/química , Hidrogéis/farmacologia , Teste de Materiais , Metacrilatos/farmacologia , Camundongos , Silicatos/química , Silicatos/farmacologia , Adesivos Teciduais/química , Adesivos Teciduais/farmacologia
17.
Clin Oral Investig ; 24(3): 1333-1338, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31309344

RESUMO

OBJECTIVE: The aim of this study was to evaluate the fracture resistance of simulated immature roots using Biodentine (BD) and fiber post (FP) compared with different root canal-filling materials under aging conditions. MATERIALS AND METHODS: One hundred and forty maxillary central anterior teeth were randomly divided into seven groups (n = 20/group). Negative control received no treatment. In the other groups, the root canals were prepared to simulate immature teeth. The root canals were filled with a 4-mm apical plug of BD and restored intraradicular with BD, BD + FP, composite resin (CR), CR + FP, and gutta-percha (GP). Positive controls were instrumented but without restoration. Teeth were subjected to thermocycling and received cyclic loading before fracture resistance test. Fracture resistance was conducted using a universal testing machine with a crosshead speed of 0.5 mm/min until fracture. Load to fracture was recorded in newtons (N). Data were statistically analyzed using one-way analysis of variance and Tukey's test at P < 0.05. RESULTS: Root canals restored intraradicular with BD + FP and CR + FP showed the highest fracture resistance compared with the other experimental groups (P < 0.001). There was no significant difference in the fracture resistance between CR and BD groups (P = 0.998). GP and positive control groups were significantly lower resistance to fracture than the other groups (P < 0.001). CONCLUSIONS: Intraradicular reinforcement with BD + FP and CR + FP enhanced the fracture resistance of simulated immature teeth than the other experimental groups. CLINICAL RELEVANCE: Biodentine or composite resin combined with fiber post could be used to reinforce immature teeth with an apical Biodentine plug.


Assuntos
Compostos de Cálcio/química , Análise do Estresse Dentário , Teste de Materiais , Materiais Restauradores do Canal Radicular/química , Silicatos/química , Fraturas dos Dentes/prevenção & controle , Resinas Compostas/química , Guta-Percha/química , Humanos , Técnicas In Vitro , Distribuição Aleatória , Fatores de Tempo
18.
J Appl Oral Sci ; 28: e20190105, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31800873

RESUMO

Calcium aluminate cement (CAC) has been highlighted as a promising alternative for endodontic use aiming at periapical tissue repair. However, its effects on dental pulp cells have been poorly explored. OBJECTIVE: This study assessed the impact of calcium chloride (CaCl2) and bismuth oxide (Bi2O3) or zinc oxide (ZnO) additives on odontoblast cell response to CAC. METHODOLOGY: MDPC-23 cells were exposed for up to 14 d: 1) CAC with 2.8% CaCl2 and 25% ZnO (CACz); 2) CAC with 2.8% CaCl2 and 25% Bi2O3 (CACb); 3) CAC with 10% CaCl2 and 25% Bi2O3 (CACb+); or 4) mineral trioxide aggregate (MTA), placed on inserts. Non-exposed cultures served as control. Cell morphology, cell viability, gene expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), and dentin matrix protein 1 (DMP-1), ALP activity, and extracellular matrix mineralization were evaluated. Data were compared using ANOVA (α=5%). RESULTS: Lower cell density was detected only for MTA and CACb+ compared with Control, with areas showing reduced cell spreading. Cell viability was similar among groups at days one and three (p>0.05). CACb+ and MTA showed the lowest cell viability values at day seven (p>0.05). CACb and CACb+ promoted higher ALP and BSP expression compared with CACz (p<0.05); despite that, all cements supported ALP activity. Matrix mineralization were enhanced in CACb+ and MTA. CONCLUSION: In conclusion, CAC with Bi2O3, but not with ZnO, supported the expression of odontoblastic phenotype, but only the composition with 10% CaCl2 promoted mineralized matrix formation, rendering it suitable for dentin-pulp complex repair.


Assuntos
Compostos de Alumínio/química , Compostos de Alumínio/farmacologia , Compostos de Cálcio/química , Compostos de Cálcio/farmacologia , Cimentos Dentários/química , Cimentos Dentários/farmacologia , Polpa Dentária/citologia , Polpa Dentária/efeitos dos fármacos , Fosfatase Alcalina/análise , Fosfatase Alcalina/efeitos dos fármacos , Animais , Bismuto/química , Bismuto/farmacologia , Cloreto de Cálcio/química , Cloreto de Cálcio/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Combinação de Medicamentos , Expressão Gênica/efeitos dos fármacos , Teste de Materiais , Camundongos , Odontoblastos/efeitos dos fármacos , Óxidos/química , Óxidos/farmacologia , Reprodutibilidade dos Testes , Silicatos/química , Silicatos/farmacologia , Fatores de Tempo , Óxido de Zinco/química , Óxido de Zinco/farmacologia
19.
Chemosphere ; 239: 124738, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31494316

RESUMO

Stabilization/Solidification (S/S) has been widely used in soil remediation to both improve physical properties and immobilize extensive contaminants. GGBS (granulated ground blast furnace slag)-MgO-CaO (GMCs) was used to treat Pb/Zn contaminated soil. The physical and microstructural characteristics of stabilized/solidified contaminated soil were investigated in this study. Microstructural analysis showed that the main hydration products of GMC treated contaminated soil were C-S-H and hydrotalcite like gels (Ht), which dominated the physical strength of S/S soil. The unconfined compressive strength (UCS) and the leachability of GMC treated contaminated soil were improved with the increase in GMC proportion (5%-15%), curing time (7 days and 28 days) and temperature (5 °C, 21 °C and 45 °C) due to the enhanced hydration. The compressive strengths of the majority mixes met the US EPA criterion (0.35 MPa). The strength of S/S soils was less affected by the increase of curing temperature after a longer curing period (28 days). According to the XRD and SEM results, both Pb and Zn in S/S contaminated soil could be immobilized by the precipitation and the adsorption on the surface of calcium silicate hydrate (C-S-H). Zn can also be incorporated into the structure of C-S-H and Ht. The addition of Pb/Zn decreased the physical strength in the order of: Pb(5000 mg/kg)>Pb(10000 mg/kg)>Zn/Pb(5000 mg/kg)>Pb(20000 mg/kg).


Assuntos
Recuperação e Remediação Ambiental/métodos , Chumbo/química , Poluentes do Solo/química , Solo/química , Zinco/química , Hidróxido de Alumínio/química , Compostos de Cálcio/química , China , Hidróxido de Magnésio/química , Óxido de Magnésio/química , Microscopia Eletrônica de Varredura , Óxidos/química , Silicatos/química , Temperatura , Difração de Raios X
20.
Phys Med Biol ; 65(3): 035012, 2020 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-31855854

RESUMO

Time-of-flight (TOF) is now a standard technology for positron emission tomography (PET), but its effective use for small diameter PET systems has not been studied well. In this paper, we simulated a brain-dedicated TOF-PET system with a hemispherical detector arrangement. We modeled a Hamamatsu TOF-PET module (C13500-4075LC-12) with 280 ps coincidence resolving time (CRT), in which a 12 × 12 array of multi pixel photon counters (MPPCs) is connected to a lutetium fine silicate (LFS) crystal array of 4.1 × 4.1 mm2 cross section each, based on one-to-one coupling. On the other hand, spatial resolution degradation due to the parallax error should be carefully addressed for the small diameter PET systems. The ideal PET detector would have both depth-of-interaction (DOI) and TOF capabilities, but typical DOI detectors that are based on light sharing tend to degrade TOF performance. Therefore, in this work, we investigated non-DOI detectors with an appropriate crystal length, which was a compromise between suppressed parallax error and decreased sensitivity. Using GEANT4, we compared two TOF detectors, a 20 mm long non-DOI and a 10 mm long non-DOI, with a non-TOF, 4-layer DOI detector with a total length of 20 mm (i.e. 5 × 4 mm). We simulated a contrast phantom and evaluated the relationship between the contrast recovery coefficient (CRC) and the noise level (the coefficient of variation, COV) for reconstructed images. The 10 mm long non-DOI, which reduces the parallax error at the cost of sensitivity loss, showed better imaging quality than the 20 mm long non-DOI. For example, the CRC value of a 10 mm hot sphere at COV = 20% was 72% for the 10 mm long non-DOI, which was 1.2 times higher than that of the 20 mm long non-DOI. The converged CRC values for the 10 mm long non-DOI were almost equivalent to those of the non-TOF 4-layer DOI, and the 10 mm long non-DOI converged faster than the non-TOF 4-layer DOI did. Based on the simulation results, we evaluated a one-pair prototype system of the TOF-PET detectors with 10 mm crystal length, which yielded the CRT of 250 ± 8 ps. In summary, we demonstrated support for feasibility of the brain-dedicated TOF-PET system with the hemispherical detector arrangement.


Assuntos
Encéfalo/diagnóstico por imagem , Imagens de Fantasmas , Fótons , Tomografia por Emissão de Pósitrons/instrumentação , Tomografia por Emissão de Pósitrons/métodos , Desenho de Equipamento , Humanos , Processamento de Imagem Assistida por Computador/métodos , Lutécio/química , Método de Monte Carlo , Projetos de Pesquisa , Silicatos/química
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