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1.
J Appl Oral Sci ; 28: e20190516, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32236357

RESUMO

INTRODUCTION: This study investigated the effect of a calcium hydroxide (CH) paste (CleaniCal®) containing N-2-methyl pyrrolidone (NMP) as a vehicle on Enterococcus faecalis (E. faecalis) biofilms compared with other products containing saline (Calasept Plus™) or propylene glycol (PG) (Calcipex II®). METHODOLOGY: Standardized bovine root canal specimens were used. The antibacterial effects were measured by colony-forming unit counting. The thickness of bacterial microcolonies and exopolysaccharides was assessed using confocal laser scanning microscopy. Morphological features of the biofilms were observed using field-emission scanning electron microscopy (FE-SEM). Bovine tooth blocks covered with nail polish were immersed into the vehicles and dispelling was observed. The data were analyzed using one-way analysis of variance and Tukey tests (p<0.05). RESULTS: CleaniCal® showed the highest antibacterial activity, followed by Calcipex II® (p<0.05). Moreover, NMP showed a higher antibacterial effect compared with PG (p<0.05). The thickness of bacteria and EPS in the CleaniCal® group was significantly lower than that of other materials tested (p<0.05). FE-SEM images showed the specimens treated with Calasept Plus™ were covered with biofilms, whereas the specimens treated with other medicaments were not. Notably, the specimen treated with CleaniCal® was cleaner than the one treated with Calcipex II®. Furthermore, the nail polish on the bovine tooth block immersed in NMP was completely dispelled. CONCLUSIONS: CleaniCal® performed better than Calasept Plus™ and Calcipex II® in the removal efficacy of E. faecalis biofilms. The results suggest the effect might be due to the potent dissolving effect of NMP on organic substances.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Hidróxido de Cálcio/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Pirrolidinonas/farmacologia , Irrigantes do Canal Radicular/farmacologia , Análise de Variância , Animais , Cloreto de Cálcio/química , Cloreto de Cálcio/farmacologia , Hidróxido de Cálcio/química , Bovinos , Contagem de Colônia Microbiana , Combinação de Medicamentos , Teste de Materiais , Microscopia Confocal , Microscopia Eletrônica de Varredura , Cloreto de Potássio/química , Cloreto de Potássio/farmacologia , Pirrolidinonas/química , Reprodutibilidade dos Testes , Irrigantes do Canal Radicular/química , Bicarbonato de Sódio/química , Bicarbonato de Sódio/farmacologia , Cloreto de Sódio/química , Cloreto de Sódio/farmacologia , Estatísticas não Paramétricas
2.
Food Chem ; 314: 126206, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31951888

RESUMO

The effects of Ca(OH)2 on the physicochemical, mechanical and microstructural characteristics, intermolecular forces and protein patterns of preserved egg white (PEW) were investigated. Results suggested that Ca(OH)2 (0.1%) reduced the free alkalinity content and turbidity and increased the brightness of PEW. The surface hydrophobicity of PEW protein with added Ca(OH)2 decreased during the pickling period owing to the hydrophobic residues being hidden in the interior of the protein. Total content of sulfhydryl and disulfide bonds in PEW decreased. Non-specific cross-linking, hydrogen bonds and hydrophobic interactions were the primary intermolecular forces. For textural properties, hardness and springiness had obvious prominence. A loose porous and regular network-like microstructure formed as the Ca(OH)2 increased and Ca(OH)2 delayed denaturation of the PEW protein. The physical properties of PEW correlated with molecular interactions and the microenvironment. Ca(OH)2 improved the contribution of surface hydrophobicity, disulfide bonds and hydrophobic interactions to the gelation process.


Assuntos
Hidróxido de Cálcio/química , Clara de Ovo/química , Animais , Proteínas do Ovo/química , Géis/química , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas
3.
Braz Oral Res ; 33: e042, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31508725

RESUMO

This study evaluated the cytotoxicity and biocompatibility of a new bioceramic endodontic sealer (i.e., Sealer Plus BC) in comparison with those of MTA Fillapex and AH Plus. L929 fibroblasts were cultured and Alamar Blue was used to evaluate cell viability of diluted extracts (1:50, 1:100, and 1:200) from each sealer at 24 h. Polyethylene tubes that were filled with material or empty (as a control) were implanted in the subcutaneous tissue of rats. The rats were killed after 7 and 30 d (n = 8), and the tubes were removed for histological analysis. Parametric data was analyzed using a one-way ANOVA test, and nonparametric data was analyzed via the Kruskal-Wallis test followed by the Dunn test (p < 0.05). A reduction in cell viability was observed in the extracts that were more diluted for Sealer Plus BC when compared to that of Control and AH Plus (p < 0.05). However, the 1:50 dilution of the Sealer Plus BC was similar to that of the Control (p > 0.05). Conversely, more diluted extracts of MTA Fillapex (1:200) and AH Plus (1:100 and 1:200) were similar to the Control (p > 0.05). Histological analysis performed at 7 d did not indicate any significant difference between tissue response for all materials, and the fibrous capsule was thick (p > 0.05). At 30 d, Sealer Plus BC was similar to the Control (p > 0.05) and MTA Fillapex and AH Plus exhibited greater inflammation than the Control (p < 0.05). The fibrous capsule was thin for the Control and for most specimens of Sealer Plus BC and AH Plus. Thus, Sealer Plus BC is biocompatible when compared to MTA Fillapex and AH Plus, and it is less cytotoxic when less-diluted extracts are used.


Assuntos
Cimentos para Ossos/química , Hidróxido de Cálcio/química , Cerâmica/química , Materiais Restauradores do Canal Radicular/química , Compostos de Alumínio/química , Animais , Materiais Biocompatíveis , Cimentos para Ossos/farmacologia , Cimentos para Ossos/toxicidade , Compostos de Cálcio/química , Hidróxido de Cálcio/farmacologia , Hidróxido de Cálcio/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas/efeitos dos fármacos , Combinação de Medicamentos , Resinas Epóxi/química , Fibroblastos/efeitos dos fármacos , Técnicas In Vitro , Inflamação , Masculino , Teste de Materiais , Óxidos/química , Ratos Wistar , Materiais Restauradores do Canal Radicular/toxicidade , Silicatos/química , Tela Subcutânea/patologia
4.
Bioengineered ; 10(1): 397-408, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31526157

RESUMO

Nowadays, there is an increasing concern toward substituting the scarce wood fibers with alternative lignocellulosic fibers that originate from crop residue to reinforce biocomposites. In this paper, the potential application of coffee hull (CH) of the reinforced polyethylene (PE) matrix composites was studied for the first time. Experiments of composite that enhanced with CH on mechanical properties, hydroscopicity, thermogravimetric analysis, fiber treatment, and microstructures were tested in this study. The PE matrix was reinforced with varying volume fractions of CH and was studied. The results show that incorporation of coffee hull markedly improved the mechanical properties of the reinforced high-density polyethylene (HDPE) matrix composites. Micrographs show a strong interfacial adhesion between the CH fiber particles. This property may be the main reason for the stability between composites. At the same time this work investigated the effect of different treatments on the mechanical properties and water absorption behavior of composites. The fiber surface treatments were done using active chemicals such as calcium hydroxide (Ca(OH)2), silane coupling agent (SCA), maleic anhydride grafted polypropylene (MA-g-PP), stearic acid (SA), ethylene bis stearamide (EBS) and the combination (MA-g-PP, SA, EBS). The results show that (Ca(OH)2)treatment is the best way to improve its properties. Probably because attributed to removal of surface active functional groups (-OH) from the CH fiber and induction of hydrophobicity that in turn improved the compatibility with the polymer matrix. As a result, the use of coffee hull in composites could have great significance for the industry.


Assuntos
Café/química , Manufaturas , Plásticos/síntese química , Polietileno/química , Hidróxido de Cálcio/química , Humanos , Interações Hidrofóbicas e Hidrofílicas , Anidridos Maleicos/química , Teste de Materiais , Plásticos/química , Silanos/química , Ácidos Esteáricos/química , Temperatura , Resistência à Tração , Resíduos , Molhabilidade
5.
Microsc Res Tech ; 82(11): 1862-1868, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31368166

RESUMO

OBJECTIVE: The aim of this study was to evaluate the efficacy of different irrigation protocols in removing two tricalcium silicate-based sealers from simulated root canal irregularities and root canal walls. MATERIAL AND METHODS: Root canals of 140 single-rooted teeth were instrumented. In one-half of each root, an apical groove was created. The samples were divided into two main groups (n = 70) based on the sealer used. In group 1, the grooves were filled with MTA Fillapex; in group 2, BioRoot RCS. The reassembled root halves were divided into six experimental and one control groups: 2.5% NaOCl-17% EDTA (Passive ultrasonic irrigation [PUI]), 5% NaOCl/9% DualRinse HEDP (PUI), 2.5% NaOCl-7% Maleic acid (PUI), 2.5% NaOCl-17% EDTA (Er:YAG laser activated irrigation [LAI]), 2.5% NaOCl/9% DualRinse HEDP (LAI), 2.5% NaOCl-7% Maleic acid (LAI), Distilled water (Control). Specimens were scored using SEM. The data were analysed using Kruskal-Wallis and Mann Whitney U tests. RESULTS: Maleic acid and DualRinse HEDP removed higher amounts of MTA Fillapex from the grooves compared to EDTA, when used with both activation methods (p < .001). CONCLUSIONS: Ultrasonically activated maleic acid or DualRinse HEDP can be an effective irrigation regimen in removing tricalcium silicate-based sealers.


Assuntos
Compostos de Cálcio/química , Cavidade Pulpar/química , Irrigantes do Canal Radicular/química , Silicatos/química , Irrigação Terapêutica/métodos , Hidróxido de Cálcio/química , Ácido Edético/química , Ácido Etidrônico/química , Humanos , Maleatos/química , Agentes de Capeamento da Polpa Dentária e Pulpectomia/química , Preparo de Canal Radicular/métodos , Tratamento do Canal Radicular/métodos , Dente/cirurgia
6.
Chemosphere ; 237: 124286, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31349960

RESUMO

It is cost effective and thermodynamically feasible to recover EDTA and remove potential toxic elements (PTEs) with sulfide precipitation from soil-washing wastewater produced from EDTA washing PTEs-contaminated soil. However, poor solid-liquid separation and EDTA recovery restrict its application due to a large number of fine particles formed during the precipitation process. This study investigated the effect of single factor on PTEs (Cu, Pb, Cd, and Zn) removal and solid-liquid separation from wastewater. The results showed that Zn was the most difficult to remove compared with Cu, Pb, and Cd; with the aid of Ca(OH)2, Zn removal efficiency was improved from 22.16% to 92.45%, and over 70.98 min, its average rate was 4.2 times that obtained without Ca(OH)2 dosage; undissolved Ca(OH)2 adsorbed suspended particles, acted as condensation nucleus, and promoted similar flocculation effect (self-flocculation); dissolved Ca(OH)2 modified the charge on the surface of suspended particles by changing the zeta potential from -36.77 ±â€¯1.2 mV to -25.39 ±â€¯3.06 mV and weakened the electrostatic repulsion between the suspended particles, and promoted their adsorption and flocculation precipitation, thereby improving the solid-liquid separation. The acid-recovered EDTA was analyzed in the protonated form (H4EDTA) using Fourier transform infrared (FT-IR) spectroscopy, and it maintained the same ability to extract PTEs from the soil as that of fresh EDTA over several cycles. This indicates that Ca(OH)2-enhanced sulfide precipitation can effectively treat soil-washing wastewater and recover EDTA and potentially reduce the cost of remediation techniques for PTEs-contaminated soil with EDTA-enhanced soil washing.


Assuntos
Ácido Edético/isolamento & purificação , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/isolamento & purificação , Sulfetos/química , Águas Residuárias/química , Hidróxido de Cálcio/química , Precipitação Química , Ácido Edético/química , Metais Pesados/isolamento & purificação , Reciclagem , Poluentes do Solo/análise , Eletricidade Estática , Purificação da Água/métodos
7.
Biomed Res Int ; 2019: 4676354, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31211137

RESUMO

The incorporation of nanoparticles into endodontic sealers aims at increasing antimicrobial activity of the original material. Aim. The aim of this study is to incorporate the nanostructured silver vanadate decorated with silver nanoparticles (AgVO3, at 2.5%, 5%, and 10%) into three endodontic sealers and evaluate the antibacterial activity of freshly sealers, surface topography and chemical composition, and setting time. Material and Methods. The AgVO3 was incorporated into AH Plus, Sealer 26, and Endomethasone N at concentrations 0%, 2.5%, 5%, and 10% (in mass). The antibacterial activity of freshly sealers was assessed by direct contact with Enterococcus faecalis and CFU/mL count (n=10), surface topography, and chemical composition were measured by SEM/EDS, and the setting time was measured by Gillmore needle (n=10). The Kruskal-Wallis and Dunn statistical tests were applied (α=0.05). Results. All groups of sealers evaluated inhibited E. faecalis (p>0.05). The incorporation of AgVO3 altered the atomic proportions between components of the endodontic sealers, and the percentage of silver (Ag) and vanadium (V) increased proportionally to the concentrations of AgVO3. Topography analysis showed differences in components distribution on the surface of the specimens. The sealers incorporated with AgVO3 of AH Plus presented a lower setting time than the control group (p<0.05). For Sealer 26 and Endomethasone N, the incorporation of AgVO3 increased the setting time in relation to control group (p<0.05). Conclusions. The modification of endodontic sealers by AgVO3 increased the atomic percentage of Ag and V proportionally to the concentration of the nanomaterial and changed the atomic percentage of the sealer components and setting times. It cannot be affirmed that the AgVO3 promote differences in the antimicrobial activity of freshly sealers, and further investigations of the antimicrobial activity of the set sealers should be carried out.


Assuntos
Antibacterianos , Bismuto , Hidróxido de Cálcio , Enterococcus faecalis/crescimento & desenvolvimento , Nanoestruturas/química , Materiais Restauradores do Canal Radicular , Compostos de Prata , Vanadatos , Antibacterianos/farmacologia , Bismuto/química , Bismuto/farmacologia , Hidróxido de Cálcio/química , Hidróxido de Cálcio/farmacologia , Dexametasona/química , Dexametasona/farmacologia , Combinação de Medicamentos , Formaldeído/química , Formaldeído/farmacologia , Humanos , Hidrocortisona/química , Hidrocortisona/farmacologia , Materiais Restauradores do Canal Radicular/química , Materiais Restauradores do Canal Radicular/farmacologia , Compostos de Prata/química , Compostos de Prata/farmacologia , Timol/análogos & derivados , Timol/química , Timol/farmacologia , Vanadatos/química , Vanadatos/farmacologia
8.
J Appl Oral Sci ; 27: e20180030, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-31116277

RESUMO

OBJECTIVES: To evaluate the effect of calcium hydroxide (CH) associated with two different vehicles as a capping material for pulp tissue in primary molars, compared with mineral trioxide aggregate (MTA). METHODOLOGY: Forty-five primary mandibular molars with dental caries were treated by conventional pulpotomy using one of the following materials: MTA only (MTA group), CH with saline (CH+saline group) and CH with polyethylene glycol (CH+PEG group) (15 teeth/group). Clinical and periapical radiographic examinations of the pulpotomized teeth were performed 3, 6, and 12 months after treatment. Data were tested by chi-squared analysis and a multiple comparison post-test. RESULTS: The MTA group showed both clinical and radiographic treatment success in 14/14 teeth (100%), at all follow-up appointments. By clinical evaluation, no teeth in the CH+saline and CH+PEG groups had signs of mobility, fistula, swelling or inflammation of the surrounding gingival tissue. However, in the CH+saline group, radiographic analysis detected internal resorption in up to 9/15 teeth (67%), and inter-radicular bone resorption and furcation radiolucency in up to 5/15 teeth (36%), from 3 to 12 months of follow-up. In the CH+PEG group, 2/11 teeth (18%) had internal resorption and 1/11 teeth (9%) presented bone resorption and furcation radiolucency at all follow-up appointments. CONCLUSION: CH with PEG performed better than CH with saline as capping material for pulpotomy of primary teeth. However, both combinations yielded clinical and radiographic results inferior to those of MTA alone.


Assuntos
Compostos de Alumínio/uso terapêutico , Compostos de Cálcio/uso terapêutico , Hidróxido de Cálcio/uso terapêutico , Óxidos/uso terapêutico , Agentes de Capeamento da Polpa Dentária e Pulpectomia/uso terapêutico , Pulpotomia/métodos , Silicatos/uso terapêutico , Dente Decíduo/cirurgia , Hidróxido de Cálcio/química , Criança , Pré-Escolar , Combinação de Medicamentos , Seguimentos , Humanos , Estudos Prospectivos , Agentes de Capeamento da Polpa Dentária e Pulpectomia/química , Radiografia Dentária , Solução Salina/química , Solução Salina/uso terapêutico , Fatores de Tempo , Dente Decíduo/diagnóstico por imagem , Resultado do Tratamento
9.
Chemosphere ; 231: 134-139, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31129393

RESUMO

In this work, the removal of arsenic from aqueous solution by using FeSO4 with CaCO3 was investigated. Arsenic removal was significantly improved in the presence of CaCO3, compared with Ca(OH)2, giving an arsenic removal rate of 99.64% with the Fe/As molar ratio of 2:1 and Ca/Fe molar ratio of 1.5:1. With both FeSO4+Ca(OH)2 (FSCH) and FeSO4+CaCO3 (FSCC), several analytical methods including SEM-EDS, XRD, FTIR, and TG-DSC etc. were performed to characterize the sediments. The sediment from FSCC has much larger particle size, six time faster filtration speed and only one-third volume compared with that from traditional FSCH, allowing a very easy handling of the precipitate sludge, another clear advantage of using CaCO3. Moreover, much less fine and sticky CaSO4 was generated in the FSCC sludge than that from FSCH.


Assuntos
Arsênico/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Arsênico/análise , Carbonato de Cálcio/química , Hidróxido de Cálcio/química , Compostos Férricos/química , Filtração , Esgotos , Água , Poluentes Químicos da Água/análise
10.
Environ Sci Pollut Res Int ; 26(19): 19320-19326, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31073839

RESUMO

As a commonly used surfactant, sodium dodecyl sulfate (SDS) usually coexists with inorganic anions in the industrial wastewater. These anions have a significant influence on SDS removal, indirectly threatening the environment. It is important to understand the relationship between the adsorption of SDS and inorganic anions. In this study, calcium-based layered double hydroxide (CaAl-LDH-Cl) as an efficient adsorbent was synthesized for investigating the effect of SO42- on SDS removal. The SDS adsorption capacities were enhanced to 3.21 and 4.21 mmol g-1 in the presence of SO42- with low/high SDS concentration, respectively. The phenomenon and mechanism were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Scanning electron microscopy (SEM). Anionic exchange played a dominant role in the adsorption of SDS onto CaAl-LDH-Cl at DS-/SO42- < 2, while both anion exchange and precipitation occurred when DS-/SO42- exceeded 2. Moreover, the thermal analysis (TG-DTA) was employed to further reveal the interaction mechanism. The results showed the highest total mass loss and the lowest loss temperature of interlayer water in the sulfate coexist system, confirming the enhancement of SDS adsorption amount in the presence of SO42-.


Assuntos
Hidróxido de Cálcio/química , Dodecilsulfato de Sódio/análise , Sulfatos/química , Tensoativos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Propriedades de Superfície , Águas Residuárias/química
11.
PLoS One ; 14(4): e0215677, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31026294

RESUMO

This study aims at evaluating the effect of ultrafine granulated copper slag (UGCS) on hydration development of blended cement and mechanical properties of mortars. The UGCS with the median particle size of 4.78 µm and BET surface area of 1.31 m2/g was used as a cement replacement to prepare blended cements. Hydration heat emission of blended cement and mechanical performance of mortars were investigated by using isothermal calorimetry and strength tests, respectively. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were applied to the analysis of pozzolanic reaction and hydration products. The results illustrate that UGCS has influence on the hydration heat evolution of blended cement due to its filler effect and pozzolanic reaction. The cumulative hydration heat of blended cement is reduced by partial cement replacement with UGCS. The test mortar prepared by using blended cements with 30 wt. % UGCS shows a retardation of strength development with a low value at early ages (7 days) and a rapid growth at later ages (28 days). The 90-day compressive strength of test mortar is 45.0 MPa close to that of the control mortar (49.5 MPa). The obtained results from XRD and TGA analysis exhibit an increase in calcium hydroxide (CH) consumption and calcium silicate hydrates (C-S-H) formation in blended cement pastes with curing time. The cement replacement with UGCS induces changes in microstructure of blended cement paste and chemical composition of hydration products.


Assuntos
Compostos de Cálcio/química , Materiais de Construção , Cobre/química , Teste de Materiais , Silicatos/química , Hidróxido de Cálcio/química , Calorimetria , Força Compressiva , Indústria da Construção/métodos , Tamanho da Partícula , Difração de Raios X
12.
Sci Total Environ ; 670: 1133-1139, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31018429

RESUMO

The primary biological treatment method for organic sludge is composting and/or anaerobic digestion, but their product (compost or biogas) is of little economic benefit; therefore, an improved process to produce a high-value product is required to make sludge management more sustainable. Maximizing NH3 gas recovery during composting processes has the potential benefit of producing high-value microalgal biomass. However, the majority of produced ammonia does not evaporate as NH3 gas but retains as NH4+-N in the compost after fermentation. The present study investigates the effects of the timing of Ca(OH)2 dosing (on days 2, 5, and 9), and the Ca(OH)2 dose (1.1-2.6 mmol/batch), on lab-scale thermophilic composting of anaerobic sludge. The effects on NH3 recovery, organic matter degradability, and microbial activity are evaluated. Ca(OH)2 dosing immediately improved the emission of NH3, with yields 50-69% higher than those under control conditions. The timing of the dosing did not influence NH3 recovery or organic matter degradability. Higher Ca(OH)2 doses resulted in higher NH3 recovery, while microbial activity was temporarily and marginally inhibited. The pH of the compost reached 10-11.5 but quickly dropped to 8-8.5 within a day, probably because of neutralization of Ca(OH)2 by the emitted CO2 and release of NH3, which maintained the microbial activity. The present study indicated that Ca(OH)2 dosing would be useful to apply during thermophilic composting for NH3 recovery to cultivate high-value microalgal biomass, which enables this process to obtain a more economic benefit.


Assuntos
Amônia/análise , Hidróxido de Cálcio/química , Compostagem , Esgotos/análise , Anaerobiose , Relação Dose-Resposta a Droga
13.
Diving Hyperb Med ; 49(1): 48-56, 2019 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-30856667

RESUMO

INTRODUCTION: Diving rebreathers use canisters containing soda lime to remove carbon dioxide (CO2) from expired gas. Soda lime has a finite ability to absorb CO2. Temperature sticks monitor the exothermic reaction between CO2 and soda lime to predict remaining absorptive capacity. The accuracy of these predictions was investigated in two rebreathers that utilise temperature sticks. METHODS: Inspiration and rEvo rebreathers filled with new soda lime were immersed in water at 19°C and operated on mechanical circuits whose ventilation and CO2-addition parameters simulated dives involving either moderate exercise (6 MET) throughout (mod-ex), or 90 minutes of 6 MET exercise followed by 2 MET exercise (low-ex) until breakthrough (inspired PCO2 [PiCO2] = 1 kPa). Simulated dives were conducted at surface pressure (sea-level) (low-ex: Inspiration, n = 5; rEvo, n = 5; mod-ex: Inspiration, n = 7, rEvo, n = 5) and at 3-6 metres' sea water (msw) depth (mod-ex protocol only: Inspiration, n = 8; rEvo, n = 5). RESULTS: Operated at surface pressure, both rebreathers warned appropriately in four of five low-ex tests but failed to do so in the 12 mod-ex tests. At 3-6 msw depth, warnings preceded breakthrough in 11 of 13 mod-ex tests. The rEvo warned conservatively in all five tests (approximately 60 minutes prior). Inspiration warnings immediately preceded breakthrough in six of eight tests, but were marginally late in one test and 13 minutes late in another. CONCLUSION: When operated at even shallow depth, temperature sticks provided timely warning of significant CO2 breakthrough in the scenarios examined. They are much less accurate during simulated exercise at surface pressure.


Assuntos
Dióxido de Carbono , Mergulho , Hidróxido de Sódio , Compostos de Cálcio/química , Hidróxido de Cálcio/química , Dióxido de Carbono/química , Humanos , Respiração , Hidróxido de Sódio/química , Temperatura , Água
14.
Ecotoxicol Environ Saf ; 174: 305-314, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30849650

RESUMO

As soil cadmium (Cd) contamination becomes a serious concern and one of the significant environmental pollution issues all over the world, knowledge of the basic chemistry, origin, inputs, sources, quantity, chemical forms, reactions, as well as the fate and transport of Cd in different types of soil is crucial for better understanding Cd bioavailability, health risks and remedial options. This study aimed to increase the current knowledge on the complex interdependence between the factors affecting behavior, transport and fate of Cd in the soil and to test and compare the performance of the stabilization agents in different soil types. Soils demonstrated various sorption affinity and capacity for Cd accumulation, which proved to be positively correlated with soil pH and the cation exchange capacity (CEC). With increasing levels of contamination, sequential extraction analysis showed the highest increase of relative Cd amounts in the exchangeable fraction regardless of the soil properties, suggesting that added Cd is principally associated with the easily accessible and mobile fraction. For different initial Cd concentrations and soil types, Cd sorption reached the quasi-equilibrium within 24 h of contact. Prolonged aging (two months) influenced the natural stabilization of Cd in all types of soil, but only at low contamination level. The application of both, conventional (slaked lime Ca(OH)2) and alternative phosphate-rich (annealed bovine bones B400) amendments, resulted in Cd relocation and reduction of exchangeable Cd content. Although the effect was smaller when apatite amendment was utilized, observed re-distribution of Cd to more stable soil fractions is preferable for achieving long-term stabilization. Cd concentrations extracted in exchangeable and acid soluble fractions after the treatments of contaminated soil samples suggest that the practical applicability of in situ immobilization depends on the soil properties and the level of contamination, as well as that effect, should be monitored for the possible re-mobilization of Cd.


Assuntos
Cádmio/análise , Hidróxido de Cálcio/química , Fertilizantes/análise , Fosfatos/análise , Poluentes do Solo/análise , Solo/química , Animais , Disponibilidade Biológica , Recuperação e Remediação Ambiental , Fatores de Tempo
15.
J Appl Oral Sci ; 27: e20180291, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30810637

RESUMO

OBJECTIVE: The aim of this study was to investigate the cytotoxic effects of modified triple antibiotic paste and an experimental composition using calcium hydroxide on lipoteichoic acid (LTA)-primed apical papilla cells (APC). MATERIAL AND METHODS: Human APC were tested for in vitro cytotoxicity of modified Triple Antibiotic Paste (mTAP - Ciprofloxacin, Metronidazole and Cefaclor at 1:1:1) and of a paste of Ciprofloxacin, Metronidazole and Calcium hydroxide (CMC - 1:1:2) and modified CMC (mCMC - 2:2:1) by using MTT assay. The substances were reconstituted in DMEM at 1,000 µg/mL and » serially diluted before being kept in contact with cells for 1, 3, 5 and 7 days. Further, cells were primed with 1 µg/mL of Enterococcus faecalis LTA for 7 days prior to the viability test with 1,000 µg/mL of each substance. Statistical analysis was performed using one-way analysis of variance (ANOVA) and two-way ANOVA respectively followed by Tukey's post-test. Significance levels were set at p<0.05. RESULTS: In the first assay, the higher cytotoxic rates were reached by mTAP for all experimental periods. CMC was found toxic for APC at 5 and 7 days, whereas mCMC did not affect the cell viability. Only CMC and mCMC were able to induce some cellular proliferation. In the second assay, when considering the condition with medium only, LTA-primed cells significantly proliferated in comparison to LTA-untreated ones. At this context, mTAP and CMC showed similar cytotoxicity than the observed for LTA-untreated cells, while mCMC was shown cytotoxic at 7 days only for LTA-primed APC. Comparing the medications, mTAP was more cytotoxic than CMC and mCMC. CONCLUSION: mTAP showed higher cytotoxicity than CMC and mCMC and the effect of topic antimicrobials might differ when tested against apical papilla cells under physiological or activated conditions.


Assuntos
Antibacterianos/toxicidade , Papila Dentária/citologia , Enterococcus faecalis/química , Lipopolissacarídeos/toxicidade , Ácidos Teicoicos/toxicidade , Ápice Dentário/citologia , Adolescente , Análise de Variância , Antibacterianos/química , Hidróxido de Cálcio/química , Hidróxido de Cálcio/toxicidade , Cefaclor/química , Cefaclor/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Ciprofloxacino/química , Ciprofloxacino/toxicidade , Papila Dentária/efeitos dos fármacos , Feminino , Humanos , Masculino , Metronidazol/química , Metronidazol/toxicidade , Reprodutibilidade dos Testes , Irrigantes do Canal Radicular/toxicidade , Fatores de Tempo , Ápice Dentário/efeitos dos fármacos
16.
Braz Oral Res ; 33: e005, 2019 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-30758405

RESUMO

The objective of this study was to assess the influence of chlorhexidine (liquid and gel) and zinc oxide in calcium hydroxide (CH) pastes on root pH in simulated external resorption. One hundred human anterior teeth with a single root canal were selected. After decoronation and root canal instrumentation, the specimens were divided into 4 experimental groups and 1 control group (without intracanal paste): CH + saline (CH+S), CH + 2% chlorhexidine liquid (CH+ CHX), CH + 2% chlorhexidine gel (CH+ CHXg), and CH + 2% chlorhexidine gel + zinc oxide (CH+ CHXg+ZnO). pH was measured using a microelectrode at 3 and 24 h, and 1, 2, 3, and 4 weeks after inserting intracanal pastes. Data were analyzed statistically using an ANOVA and Tukey's test (p < 0.05). The CH+CHXg+ZnO group had the highest pH values throughout (p<0.05). The CH+S and CH+ CHX groups had the highest pH values after 1 week and the CH+ CHXg group after 2 weeks. CH+ CHXg maintained the highest pH until the fourth week compared with CH+ CHX (p < 0.05). The control group remained at a neutral pH at all evaluated times. It can be concluded that chlorhexidine solution or gel maintained the alkaline pH of CH, and chlorhexidine gel allowed a slower decrease in pH over time. CH+ CHXg+ZnO showed the highest pH values and was an effective intracanal medication for maintaining alkaline root pH in the area of resorption.


Assuntos
Hidróxido de Cálcio/química , Clorexidina/química , Irrigantes do Canal Radicular/química , Raiz Dentária/efeitos dos fármacos , Óxido de Zinco/química , Análise de Variância , Géis , Humanos , Concentração de Íons de Hidrogênio , Teste de Materiais , Pomadas , Valores de Referência , Reprodutibilidade dos Testes , Reabsorção da Raiz/tratamento farmacológico , Estatísticas não Paramétricas , Propriedades de Superfície/efeitos dos fármacos , Fatores de Tempo
17.
Int J Biol Macromol ; 128: 994-1001, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30769043

RESUMO

Recently, calcium hydroxide and magnesium hydroxide nanoparticles have attracted a lot of research interest in different sectors: food, packaging, health, automotive construction and food application. In the present study, we report development of bio-material calcium hydroxide nanoparticles (Ceg-Ca(OH)2), obtained from chicken eggshell collected from the food industries as well as magnesium hydroxide nanoparticles obtained from seawater (Seaw-Mg(OH)2). The flame-retardant behavior of Ethylene-Vinyl Acetate copolymer (EVA) containing different blends of Ceg-Ca(OH)2 and Seaw-Mg(OH)2 nanoparticles has been evaluated using cone calorimeter. Our results showed the interest of combining both nanoparticles. In fact, the partial substitution of small Seaw-Mg(OH)2 content (10 wt%) by Ceg-Ca(OH)2 enables further reduction of pHRR from 251 to 206 kW/m2 without any reduction of the composite time to ignition (52 s). Furthermore, the partial substitution of 40 wt% Seaw-Mg(OH)2 nanoparticles by Ceg-Ca(OH)2 enables high flame retardant effect as well as the generation of cohesive residue.


Assuntos
Hidróxido de Cálcio/química , Retardadores de Chama , Hidróxido de Magnésio/química , Nanopartículas/química , Polivinil/química , Água do Mar/química , Resíduos , Animais , Casca de Ovo/química , Teste de Materiais , Temperatura
18.
Food Chem ; 283: 83-91, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30722929

RESUMO

This work focused in the study of the changes on the physicochemical properties of isolated jícama starch (IJS), and IJS added with 0.15, 0.20, 0.30% Ca(OH)2 w/w. including: the structural, morphological, chemical, vibrational, pasting, rheological, and thermal characteristics. K, Ca, Na, and P were found in IJS. X-ray patterns, which showed that nanocrystals form the IJS according to the PDF-4 simulation. The functional properties were affected by the Ca inclusion, which originated electrostatic interactions. The gelatinization temperatures shifted to high values and exhibited an unfolding. The calculation of the IR absorption coefficient (ß) of the gelatinized samples as a function of the Ca2+ for the C-OH showed that the Van der Waals interaction causes the changes in the rheological-mechanical properties. The SEM images demonstrated that starch without alkali exhibited a porous network structure, while the starch with lime exhibited flakes and porous network. The gels of Jicama starch with Ca(OH)2 showed a viscoelastic behavior (G' > G″) with a reduction of their elastic module.


Assuntos
Hidróxido de Cálcio/química , Pachyrhizus/metabolismo , Amido/química , Amilose/metabolismo , Microscopia Eletrônica de Varredura , Nanopartículas/química , Reologia , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Temperatura , Viscosidade , Difração de Raios X
19.
J Mater Sci Mater Med ; 30(2): 17, 2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30671677

RESUMO

Enterococcus faecalis (E. faecalis), a Gram-positive facultative anaerobe, is reported to take responsibility for a large portion of refractory root canal infections and root canal re-infections of human teeth. Chlorhexidine is a strong bactericide against E. faecalis but cannot infiltrate into dentinal tubules. On the other hand, a common negative effect of root canal medicaments is the decrease of dentin microhardness. In this study, poly(D,L-lactic-co-glycolide) (PLGA) submicron particles were applied as delivery carriers to load and release the chlorhexidine as well as calcium and phosphorus. The release profiles, antibacterial ability against E. faecalis, infiltration ability into dentinal tubules, biocompatibility and effects on dentin microhardness of these particles were investigated. Results revealed that encapsulated chemicals could be released in a sustained manner from the particles. The particles also exhibited excellent biocompatibility on MC3T3-E1 cells and significant antimicrobial property against E. faecalis. On dentin slices, the particles could be driven into dentinal tubules by ultrasonic activiation and inhibit E. faecalis colonization. Besides, dentin slices medicated with the particles displayed an increase in microhardness. In conclusion, PLGA submicron particles carrying chlorhexidine, calcium and phosphorus could be developed into a new intra-canal disinfectant for dental treatments.


Assuntos
Cálcio/química , Clorexidina/administração & dosagem , Dentina/química , Enterococcus faecalis/efeitos dos fármacos , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Fósforo/química , Células 3T3 , Animais , Antibacterianos , Hidróxido de Cálcio/química , Doenças da Polpa Dentária/tratamento farmacológico , Dentina/efeitos dos fármacos , Portadores de Fármacos , Dureza , Humanos , Camundongos , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Irrigantes do Canal Radicular/farmacologia , Dente/efeitos dos fármacos
20.
Int J Biol Macromol ; 127: 440-449, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30659881

RESUMO

Swelling, mechanical strength, flexibility, and toughness are important parameters in hydrogel preparation for application in the human body. Herein, composite hydrogels were prepared using a mix of Konjac glucomannan (KGM), sodium alginate (SA), and polyvinyl alcohol (PVA) cross-linked by calcium hydroxide. The PVA/KGM/SA composite hydrogel showed a suitable swelling ratio and rate, as well as elasticity and flexibility. In addition, the elongation at break was 660.3%, with a breaking strength of 87.25 kPa and a compression modulus of 1.660 MPa. Rheological studies showed that the composite hydrogel was composed of a multiply cross-linked network involving chemical and physical interactions, thereby affecting the elasticity and flexibility of the gel. Interestingly, the composite gel network was reformed when the temperature decreased. In rabbit models of dry eye, the hydrogel effectively maintained the normal tear meniscus height and increased the low tear meniscus area. The results therefore showed that the PVA/KGM/SA gels not only provide a simple, effective, and safe method for the preparation of hydrogels, but also have potential applications in the treatment of dry eye syndrome.


Assuntos
Hidrogéis , Aparelho Lacrimal , Plug Lacrimal , Alginatos/química , Animais , Hidróxido de Cálcio/química , Reagentes para Ligações Cruzadas/química , Hidrogéis/síntese química , Hidrogéis/química , Hidrogéis/farmacologia , Mananas/química , Mananas/farmacologia , Álcool de Polivinil/química , Álcool de Polivinil/farmacologia , Coelhos
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