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1.
J Phys Chem Lett ; 12(25): 5864-5870, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34142554

RESUMO

Over the last 5 years, metal halide perovskites (MHPs) have emerged as promising photocatalysts for CO2 reduction because of their extraodinary visible-light-harvesting capabilities and appropriate band structure. However, the CO2 photoreduction activity of pristine MHPs is still unsatisfactory because of the phase instability, serious radiative recombination, and insufficient surface-active sites. This Perspective summarizes the strategies employed in recent studies for enhancing the photocatalytic CO2 reduction performance of MHPs from the standpoint of structure engineering, which includes composition/dimension regulation, surface modification, and heterostructure construction. The relationship between the structure (composition, dimension, and shape) and photocatalytic performance is established, which is instructive for exploiting highly efficient perovskite-based photocatalysts in artificial photosynthesis applications. Further, some important challenges and future prospects of MHPs in this field are proposed and discussed.


Assuntos
Biomimética , Compostos de Cálcio/química , Halogênios/química , Metais/química , Óxidos/química , Fotossíntese , Titânio/química
2.
ACS Appl Mater Interfaces ; 13(25): 29392-29405, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-34137577

RESUMO

Chemiluminescence immunoassays have been widely employed for diagnosing various diseases. However, because of the extremely low intensity chemiluminescence signals, highly sensitive transducers, such as photomultiplier tubes and image sensors with cooling devices, are required to overcome this drawback. In this study, a hypersensitive photosensor was developed based on cesium lead bromide (CsPbBr3) perovskite quantum dots (QDs) with sufficient high sensitivity for chemiluminescence immunoassays. First, CsPbBr3 QDs with a highly uniform size, that is, 5 nm, were synthesized under thermodynamic control to achieve a high size confinement effect. For the fabrication of the photosensor, MoS2 nanoflakes were used as an electron transfer layer and heat-treated at an optimum temperature. Additionally, a parylene-C film was used as a passivation layer to improve the physical stability and sensitivity of the photosensor. In particular, the trap states on the CsPbBr3 QDs were reduced by the passivation layer, and the sensitivity was increased. Finally, a photosensor based on CsPbBr3 QDs was employed in chemiluminescence immunoassays for the detection of human hepatitis B surface antigen, human immunodeficiency virus antibody, and alpha-fetoprotein (AFP, a cancer biomarker). When compared with the conventionally used equipment, the photosensor was determined to be feasible for application in chemiluminescence immunoassays.


Assuntos
Compostos de Cálcio/química , Imunoensaio/métodos , Chumbo/química , Medições Luminescentes/métodos , Óxidos/química , Pontos Quânticos/química , Titânio/química , Césio/química , Anticorpos Anti-HIV/análise , Antígenos de Superfície da Hepatite B/análise , Humanos , Polímeros/química , Xilenos/química
3.
Molecules ; 26(9)2021 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-34066444

RESUMO

Dental pulp vitality is a desideratum for preserving the health and functionality of the tooth. In certain clinical situations that lead to pulp exposure, bioactive agents are used in direct pulp-capping procedures to stimulate the dentin-pulp complex and activate reparative dentinogenesis. Hydraulic calcium-silicate cements, derived from Portland cement, can induce the formation of a new dentin bridge at the interface between the biomaterial and the dental pulp. Odontoblasts are molecularly activated, and, if necessary, undifferentiated stem cells in the dental pulp can differentiate into odontoblasts. An extensive review of literature was conducted on MedLine/PubMed database to evaluate the histological outcomes of direct pulp capping with hydraulic calcium-silicate cements performed on animal models. Overall, irrespective of their physico-chemical properties and the molecular mechanisms involved in pulp healing, the effects of cements on tertiary dentin formation and pulp vitality preservation were positive. Histological examinations showed different degrees of dental pulp inflammatory response and complete/incomplete dentin bridge formation during the pulp healing process at different follow-up periods. Calcium silicate materials have the ability to induce reparative dentinogenesis when applied over exposed pulps, with different behaviors, as related to the animal model used, pulpal inflammatory responses, and quality of dentin bridges.


Assuntos
Materiais Biocompatíveis/química , Compostos de Cálcio/química , Capeamento da Polpa Dentária , Dentinogênese/efeitos dos fármacos , Silicatos/química , Compostos de Alumínio , Animais , Cerâmica , Materiais Dentários , Polpa Dentária/efeitos dos fármacos , Dentina/química , Dentina Secundária/efeitos dos fármacos , Cães , Combinação de Medicamentos , Humanos , Inflamação , Modelos Animais , Óxidos/farmacologia
4.
Nat Commun ; 12(1): 3037, 2021 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-34031392

RESUMO

Microbialites accrete where environmental conditions and microbial metabolisms promote lithification, commonly through carbonate cementation. On Little Ambergris Cay, Turks and Caicos Islands, microbial mats occur widely in peritidal environments above ooid sand but do not become lithified or preserved. Sediment cores and porewater geochemistry indicated that aerobic respiration and sulfide oxidation inhibit lithification and dissolve calcium carbonate sand despite widespread aragonite precipitation from platform surface waters. Here, we report that in tidally pumped environments, microbial metabolisms can negate the effects of taphonomically-favorable seawater chemistry on carbonate mineral saturation and microbialite development.


Assuntos
Compostos de Cálcio/química , Ecossistema , Óxidos/química , Areia/química , Areia/microbiologia , Carbonato de Cálcio/metabolismo , Carbonatos , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Microbiota , Minerais , Água do Mar/química , Água do Mar/microbiologia , Índias Ocidentais
5.
Chem Commun (Camb) ; 57(36): 4388-4391, 2021 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-33949477

RESUMO

In this study, cellulose acetate (CA) and calcium oxide was used to manufacture an CA-CaO separator with high thermal stability and was then coated on polypropylene (PP). The high melting point of CaO and the complexation of CaO and carbonyl groups in CA increased the thermal stability of CA. Because PP is known to have a higher mechanical stability than CA, the CA-CaO separator was coated twice on the PP support, increasing the stability of the entire separator. Adhesion was imparted between the CA film and the PP film without a separate adhesive due to the swelling effect of the solvent and the water pressure treatment, and pores were even formed by the pressure. Water flux data showed that cellulose acetate containing CaO coated on polypropylene (CA-CaO on PP) obtained a relatively high flux value of 71.67 L m-2 h-1 (LMH) at a pressure of 8 bar. Through thermogravimetric analysis and Fourier transform infrared data, it was confirmed that the surfaces of two polymers were bonded and the stability was improved.


Assuntos
Compostos de Cálcio/química , Celulose/análogos & derivados , Óxidos/química , Polipropilenos/química , Temperatura , Celulose/química , Tamanho da Partícula , Propriedades de Superfície
6.
Biosci Biotechnol Biochem ; 85(5): 1175-1182, 2021 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-33686392

RESUMO

Ergothioneine (ERGO), a thiohistidine betaine, exists in various fungi, plants, and animals. Humans take in ERGO from their diet. ERGO is a strong biological antioxidant, but there are only a limited number of reports about its redox mechanism. The purpose of this study was to clarify the oxidation mechanism of ERGO. Reactions of ERGO with chemical oxidants were performed. The oxidation products of ERGO were analyzed by nuclear magnetic resonance and liquid chromatography-mass spectrometry (LC-MS). The major product of oxidation of ERGO by hydrogen peroxide in physiological conditions was identified as hercynine (histidine betaine). One molecule of ERGO was able to reduce 2 molecules of hydrogen peroxide. Hercynine was found to react with the more potent oxidant hypochlorite. One unstable decomposition product was detected by LC-MS. As a result, a mechanism of oxidation of ERGO, and hence its physiological antioxidant activity, was developed.


Assuntos
Antioxidantes/química , Betaína/análogos & derivados , Compostos de Cálcio/química , Ergotioneína/química , Histidina/análogos & derivados , Peróxido de Hidrogênio/química , Oxidantes/química , Betaína/química , Cromatografia Líquida , Histidina/química , Cinética , Oxirredução , Soluções , Espectrometria de Massas em Tandem , Água/química
7.
Molecules ; 26(4)2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33670175

RESUMO

A range of solution-processed organic and hybrid organic-inorganic solar cells, such as dye-sensitized and bulk heterojunction organic solar cells have been intensely developed recently. TiO2 is widely employed as electron transporting material in nanostructured TiO2 perovskite-sensitized solar cells and semiconductor in dye-sensitized solar cells. Understanding the optical and electronic mechanisms that govern charge separation, transport and recombination in these devices will enhance their current conversion efficiencies under illumination to sunlight. In this work, density functional theory with Perdew-Burke Ernzerhof (PBE) functional approach was used to explore the optical and electronic properties of three modeled TiO2 brookite clusters, (TiO2)n=5,8,68. The simulated optical absorption spectra for (TiO2)5 and (TiO2)8 clusters show excitation around 200-400 nm, with (TiO2)8 cluster showing higher absorbance than the corresponding (TiO2)5 cluster. The density of states and the projected density of states of the clusters were computed using Grid-base Projector Augmented Wave (GPAW) and PBE exchange correlation functional in a bid to further understand their electronic structure. The density of states spectra reveal surface valence and conduction bands separated by a band gap of 1.10, 2.31, and 1.37 eV for (TiO2)5, (TiO2)8, and (TiO2)68 clusters, respectively. Adsorption of croconate dyes onto the cluster shifted the absorption peaks to higher wavelengths.


Assuntos
Teoria da Densidade Funcional , Nanoestruturas/química , Energia Solar , Titânio/química , Adsorção , Compostos de Cálcio/química , Fontes de Energia Elétrica , Eletrônica , Elétrons , Óptica e Fotônica/tendências , Óxidos/química , Luz Solar
8.
Carbohydr Polym ; 259: 117710, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33673989

RESUMO

Harmful algal blooms induce severe environmental problems. It is challenging to remove algae by the current available treatments involving complicate process and costly instruments. Here, we developed a CaO2@PEG-loaded water-soluble self-branched chitosan (CP-SBC) system, which can remove algae from water in one-step without additional instrumentation. This approach utilizes a novel flocculant (self-branched chitosan) integrated with flotation function (induced by CaO2@PEG). CP-SBC exhibited better flocculation performance than commercial flocculants, which is attributed to the enhanced bridging and sweeping effect of branched chitosan. CP-SBC demonstrated outstanding biocompatibility, which was verified by zebrafish test and algae activity test. CaO2@PEG-loaded self-branched chitosan can serve as an "Air flotation system" to spontaneous float the flocs after flocculation by sustainably released O2. Furthermore, CP-SBC can improve water quality through minimizing dissolved oxygen depletion and reducing total phosphorus concentrations.


Assuntos
Quitosana/química , Proliferação Nociva de Algas/fisiologia , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Compostos de Cálcio/química , Floculação/efeitos dos fármacos , Proliferação Nociva de Algas/efeitos dos fármacos , Cinética , Larva/efeitos dos fármacos , Óxidos/química , Oxigênio/química , Fósforo/química , Polietilenoglicóis/química , Porosidade , Peixe-Zebra/crescimento & desenvolvimento , Peixe-Zebra/fisiologia
9.
Microb Cell Fact ; 20(1): 41, 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33568151

RESUMO

BACKGROUND: Microbes are present in almost every environment on Earth, even in those with extreme environmental conditions such as Antarctica, where rocks may represent the main refuge for life. Lithobiontic communities are composed of microorganisms capable of colonizing rocks and, as it is a not so well studied bacterial community, they may represent a very interesting source of diversity and functional traits with potential for biotechnological applications. In this work we analyzed the ability of Antarctic lithobiontic bacterium to synthesize cadmium sulfide quantum dots (CdS QDs) and their potential application in solar cells. RESULTS: A basaltic andesite rock sample was collected from Fildes Peninsula, King George Island, Antarctica, and processed in order to isolate lithobiontic bacterial strains. Out of the 11 selected isolates, strain UYP1, identified as Pedobacter, was chosen for further characterization and analysis due to its high cadmium tolerance. A protocol for the biosynthesis of CdS QDs was developed and optimized for this strain. After 20 and 80 min of synthesis, yellow-green and orange-red fluorescent emissions were observed under UV light, respectively. QDs were characterized through spectroscopic techniques, dynamic light scattering analysis, high-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy. Nanostructures of 3.07 nm, composed of 51.1% cadmium and 48.9% sulfide were obtained and further used as photosensitizer material in solar cells. These solar cells were able to conduct electrons and displayed an open circuit voltage of 162 mV, a short circuit current density of 0.0110 mA cm-2, and had an efficiency of conversion up to 0.0016%, which is comparable with data previously reported for solar cells sensitized with biologically produced quantum dots. CONCLUSIONS: We report a cheap, rapid and eco-friendly protocol for the production of CdS QDs by an Antarctic lithobiontic bacterium, Pedobacter, a genus that was not previously reported as a quantum dot producer. The application of the biosynthesized QDs as sensitizer material in solar cells was validated.


Assuntos
Compostos de Cálcio/química , Pedobacter/química , Pontos Quânticos/química , Energia Solar , Sulfetos/química , Regiões Antárticas
10.
Angew Chem Int Ed Engl ; 60(16): 8905-8912, 2021 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-33527642

RESUMO

The local electron density of an atom is one key factor that determines its chemical properties. Regulating electron density can promote the atom's reactivity and so reduce the reaction activation energy, which is highly desired in many chemical applications. Herein, we report an intra-crystalline electron lever strategy, which can regulate the electron density of reaction centre atoms via manipulating ambient lattice states, for Fenton activity improvement. Typically, with the assistance of ultrasound, the Mn4+ -O-Fe3+ bond in BiFe0.97 Mn0.03 O3 perovskite nanocrystals can drive valence electrons and free electrons to accumulate on Fe atoms by a polarization electric field originated from the designed lattice strain. The increase of electron density significantly improves the catalytic activity of Fe, decreasing the activation energy of BiFe0.97 Mn0.03 O3 -mediated Fenton reaction by 52.55 %, and increasing the . OH yield by 9.21-fold. This study provides a new way to understand the sono-Fenton chemistry, and the increased . OH production enables a highly effective chemodynamic therapy.


Assuntos
Antineoplásicos/farmacologia , Compostos de Cálcio/química , Elétrons , Nanopartículas/química , Neoplasias/tratamento farmacológico , Óxidos/química , Terapia Fototérmica , Titânio/química , Antineoplásicos/química , Compostos de Cálcio/metabolismo , Humanos , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Neoplasias/metabolismo , Óxidos/metabolismo , Tamanho da Partícula , Espécies Reativas de Oxigênio/metabolismo , Titânio/metabolismo
11.
Molecules ; 26(4)2021 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-33572201

RESUMO

We synthesized and subsequently rationalized the formation of a series of 3D hierarchical metal oxide spherical motifs. Specifically, we varied the chemical composition within a family of ATiO3 (wherein "A" = Ca, Sr, and Ba) perovskites, using a two-step, surfactant-free synthesis procedure to generate structures with average diameters of ~3 microns. In terms of demonstrating the practicality of these perovskite materials, we have explored their use as supports for the methanol oxidation reaction (MOR) as a function of their size, morphology, and chemical composition. The MOR activity of our target systems was found to increase with decreasing ionic radius of the "A" site cation, in order of Pt/CaTiO3 (CTO) > Pt/SrTiO3 (STO) > Pt/BaTiO3 (BTO). With respect to morphology, we observed an MOR enhancement of our 3D spherical motifs, as compared with either ultra-small or cubic control samples. Moreover, the Pt/CTO sample yielded not only improved mass and specific activity values but also a greater stability and durability, as compared with both commercial TiO2 nanoparticle standards and precursor TiO2 templates.


Assuntos
Compostos de Cálcio/química , Metanol/química , Óxidos/química , Platina/química , Tensoativos/química , Titânio/química , Catálise , Oxirredução
12.
J Vis Exp ; (168)2021 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-33616110

RESUMO

Organic-inorganic perovskites have an impressive potential for the design of next generation solar cells and are currently considered for upscaling and commercialization. Currently, perovskite solar cells rely on spin-coating which is neither practical for large areas nor environmentally friendly. Indeed, one of the conventional and most effective lab-scale methods to induce perovskite crystallization, the antisolvent method, requires an amount of toxic solvent that is difficult to apply on larger surfaces. To solve this problem, an antisolvent-free and rapid thermal annealing process called flash infrared annealing (FIRA) can be used to produce highly crystalline perovskite films. The FIRA oven is composed of an array of near-infrared halogen lamps with an illumination power of 3,000 kW/m2. A hollow aluminum body enables an effective water-cooling system. The FIRA method allows the synthesis of perovskite films in less than 2 s, achieving efficiencies >20%. FIRA has a unique potential for the industry because it can be adapted to continuous processing, is antisolvent-free, and does not require lengthy, hour-long annealing steps.


Assuntos
Compostos de Cálcio/química , Raios Infravermelhos , Óxidos/química , Energia Solar , Solventes/química , Titânio/química , Cristalização
13.
Molecules ; 26(3)2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-33573292

RESUMO

Carbon fiber dispersion has a substantial influence on the properties of amorphous calcium silicate hydrate-based contact-hardening composites. In this study, a mixture of carbon fiber and calcium silicate hydrate powder was compressed into solid composites at 40 MPa for one minute. The mechanical properties and electrical resistivity of the solid materials were measured, and the dispersion of carbon fibers was quantitatively evaluated by digital image processing technology. The Taipalu model was used to build the correlation between the electrical resistivity of the composites and the carbon fiber dispersion. The results of the electrical resistivity showed that the down threshold of carbon fiber content in the contact-hardening composites was 1.0 wt.% and the electrical resistivity was 30,000 Ω·cm. As the fiber content increased to 2.0 wt.%, the electrical resistivity dropped to 2550 Ω·cm, which was attributed to the increase in fiber dispersion uniformity in the solid composites, and the value of the fiber distribution coefficient reached a maximum value of 0.743. A subsequent decrease in the uniformity of the fiber dispersion was observed at a high fiber content. In addition, the carbon fiber content showed a slight influence on the fiber orientation in the contact-hardening composites.


Assuntos
Compostos de Cálcio/química , Fibra de Carbono/química , Teste de Materiais , Pós/química , Silicatos/química , Eletricidade , Processamento de Imagem Assistida por Computador/métodos , Propriedades de Superfície
14.
Molecules ; 26(3)2021 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-33572957

RESUMO

Lead halide perovskites are currently widely investigated as active materials in photonic and optoelectronic devices. While the lack of long term stability actually limits their application to commercial devices, several experiments demonstrated that beyond the irreversible variation of the material properties due to degradation, several possibilities exist to reversibly modulate the perovskite characteristics by acting on the environmental conditions. These results clear the way to possible applications of lead halide perovskites to resistive and optical sensors. In this review we will describe the current state of the art of the comprehension of the environmental effects on the optical and electronic properties of lead halide perovskites, and of the exploitation of these results for the development of perovskite-based sensors.


Assuntos
Técnicas Biossensoriais , Compostos de Cálcio/química , Chumbo/química , Óptica e Fotônica/métodos , Óxidos/química , Titânio/química , Clima , Eletrônica , Monitoramento Ambiental , Humanos , Compostos Inorgânicos/química , Compostos Inorgânicos/isolamento & purificação , Chumbo/isolamento & purificação
15.
Chem Commun (Camb) ; 57(8): 994-997, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33399596

RESUMO

Hydroxyapatite nanoparticles (HAP NPs) are blended with TiO2 NPs to prepare mixed mesoporous scaffolds which are used to prepare high efficiency perovskite solar cells (PSCs) with a best power conversion efficiency (PCE) of 20.98%. HAP not only increases the PCE but also limits the concentration of Pb released in water from intentionally broken PSCs by ion sequestration thereby potentially offering a promising in-device fail-safe system.


Assuntos
Compostos de Cálcio/química , Fontes de Energia Elétrica , Chumbo/química , Óxidos/química , Energia Solar , Titânio/química , Durapatita , Microscopia Eletrônica de Varredura , Estrutura Molecular , Nanopartículas
16.
Sci Rep ; 11(1): 99, 2021 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-33420110

RESUMO

Calotropis gigantea (C. gigantea) extract with an ecofriendly nanotechnology approach could provide promising antimicrobial activity against skin pathogens. This study investigates the antimicrobial capability of green synthesized binary ZnO-CuO nanocomposites from C. gigantea against non-MDR (Staphylococcus aureus and Escherichia coli) and MDR (Klebsiella pneumoniae, Pseudomonas aeruginosa and methicillin-resistant S. aureus) skin pathogens. Scanning electron microscopy and transmission electron microscopy revealed the size and shape of B3Z1C sample. Results of X-ray powder diffraction, energy-dispersive spectroscopy, FTIR and UV-Vis spectroscopy analyses confirmed the presence of mixed nanoparticles (i.e., zinc oxide, copper oxide, carbon and calcium) and the stabilising phytochemical agents of plant (i.e., phenol and carbonyl). Antimicrobial results showed that carbon and calcium decorated binary ZnO-CuO nanocomposites with compositions of 75 wt% of ZnO and 25 wt% CuO (B3Z1C) was a strong bactericidal agent with the MBC/MIC ratio of ≤ 4 and ≤ 2 for non-MDR and MDR pathogens, respectively. A significant non-MDR zone of inhibitions were observed for BZC by Kirby-Bauer disc-diffusion test. Further time-kill observation revealed significant fourfold reduction in non-MDR pathogen viable count after 12 h study period. Further molecular studies are needed to explain the biocidal mechanism underlying B3Z1C potential.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Compostos de Cálcio/química , Compostos de Cálcio/farmacologia , Calotropis/química , Óxidos/química , Óxidos/farmacologia , Extratos Vegetais/farmacologia , Óxido de Zinco/química , Óxido de Zinco/farmacologia , Composição de Medicamentos , Avaliação Pré-Clínica de Medicamentos , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Química Verde , Humanos , Nanocompostos/química , Extratos Vegetais/química , Dermatopatias/tratamento farmacológico , Dermatopatias/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
17.
Sci Rep ; 11(1): 834, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33437013

RESUMO

To evaluate the effectiveness of a calcium silicate/phosphate fluoridated tooth paste and a serum compared with a toothpaste containing hydroxyapatite on protecting the enamel after interproximal reduction against demineralization. 3 sets of eleven incisors were created. The teeth underwent interproximal enamel reduction (IER) of 0.5 mm. Each set was allocated to one of three groups: (1) Brushing without toothpaste (control group); (2) Vitis toothpaste + Remin Pro; (3) Regenerate toothpaste + Regenerate Serum. The agents were applied three times a day and specimens subjected to demineralization cycles for 30 days. The weight percentages of calcium (Ca) and phosphorous (P) were quantified by X-ray microfluorescence spectroscopy. Surface microhardness measurements and electron scanning microscopy (SEM) observations were made. Ca data and the Ca/P ratio were significantly higher in Group 3 than the other groups (p < 0.017), while P was significantly lower in Group 3 (p < 0.017). No significant differences were found between Groups 1 and 2 (p > 0.017). Group 3 showed significantly higher microhardness values (p < 0.05) than Group 1. No significant differences were found for other comparisons between groups (p < 0.05). SEM images showed less demineralization in Group 3. The application of a calcium silicate/phosphate fluoridated tooth paste (Regenerate advance) and a dual serum (Regenerate advance enamel serum) protect the enamel with interproximal reduction against demineralization. Therefore, this treatment could be used to prevent the dissolution of hydroxyapatite after IER.


Assuntos
Compostos de Cálcio/administração & dosagem , Esmalte Dentário/efeitos dos fármacos , Silicatos/administração & dosagem , Desmineralização do Dente/tratamento farmacológico , Erosão Dentária/prevenção & controle , Remineralização Dentária/métodos , Cremes Dentais/administração & dosagem , Compostos de Cálcio/química , Fosfatos de Cálcio/análise , Cariostáticos/administração & dosagem , Esmalte Dentário/fisiologia , Dentifrícios/administração & dosagem , Fluoretos/administração & dosagem , Humanos , Microscopia Eletrônica de Varredura/métodos , Silicatos/química , Desmineralização do Dente/metabolismo , Desmineralização do Dente/patologia
18.
Molecules ; 26(2)2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33435543

RESUMO

Perovskite-type lithium ionic conductors were explored in the (LixLa1-x/3)ScO3 system following their syntheses via a high-pressure solid-state reaction. Phase identification indicated that a solid solution with a perovskite-type structure was formed in the range 0 ≤ x < 0.6. When x = 0.45, (Li0.45La0.85)ScO3 exhibited the highest ionic conductivity and a low activation energy. Increasing the loading of lithium as an ionic diffusion carrier expanded the unit cell volume and contributed to the higher ionic conductivity and lower activation energy. Cations with higher oxidation numbers were introduced into the A/B sites to improve the ionic conductivity. Ce4+ and Zr4+ or Nb5+ dopants partially substituted the A-site (La/Li) and B-site Sc, respectively. Although B-site doping produced a lower ionic conductivity, A-site Ce4+ doping improved the conductive properties. A perovskite-type single phase was obtained for (Li0.45La0.78Ce0.05)ScO3 upon Ce4+ doping, providing a higher ionic conductivity than (Li0.45La0.85)ScO3. Compositional analysis and crystal-structure refinement of (Li0.45La0.85)ScO3 and (Li0.45La0.78Ce0.05)ScO3 revealed increased lithium contents and expansion of the unit cell upon Ce4+ co-doping. The highest ionic conductivity of 1.1 × 10-3 S cm-1 at 623 K was confirmed for (Li0.4Ce0.15La0.67)ScO3, which is more than one order of magnitude higher than that of the (LixLa1-x/3)ScO3 system.


Assuntos
Compostos de Cálcio/química , Eletrodos , Eletrônica/instrumentação , Lantânio/química , Lítio/química , Óxidos/química , Escândio/química , Titânio/química , Condutividade Elétrica
19.
J Photochem Photobiol B ; 216: 112126, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33516151

RESUMO

Prolonged exposure to Ultra Violet Radiation (UVR) adversely alters the functions of many skin cell types causing skin cancer and photoaging, which had led to increase in demand for more safe and natural sunscreens against UVR. The present study focuses on production, structural characterization and evaluation of photoprotective nature of melanin pigment derived from lime dwelling Pseudomonas sp. Melanin was characterized by solubility, UV-Vis, FT-IR, 13C-CPMAS, ESI-MS spectroscopy, including particle size, melting point and elemental analyses. In vitro cytotoxicity and photo-protective effect of Pseudomonas derived melanin (Mel-P) against UV-B (Broad Band-BB) radiations were assessed on mouse fibroblasts NIH 3 T3 cell lines. Reactive Oxygen Species (ROS) generated in NIH 3 T3 cells upon UV-B (BB) exposure was determined and quantified by Fluorescent microscopic and Flow cytometric analyses. A natural melanin obtained from Pseudomonas sp. contains 5,6- dihydroxy indole 2-carboxyic acid (DHICA) as its basic constituent and possess typical properties of eumelanin as revealed by the characterization studies. Mel-P has shown cell viability of 61.33 ± 6.58% at the concentration of 500 µg/mL proving its non-cytotoxic effect. Owing to its anti-oxidant property, melanin efficiently protected the mouse fibroblast cells from UV-B (BB) irradiation in a dose dependant manner demonstrating its potential as an active photoprotective agent.


Assuntos
Compostos de Cálcio/química , Melaninas/química , Óxidos/química , Substâncias Protetoras/química , Pseudomonas/efeitos da radiação , Neoplasias Cutâneas/prevenção & controle , Protetores Solares/química , Células 3T3 , Animais , Antioxidantes/química , Antioxidantes/metabolismo , Compostos de Cálcio/metabolismo , Fibroblastos/citologia , Fibroblastos/efeitos da radiação , Humanos , Melaninas/metabolismo , Melaninas/farmacologia , Camundongos , Óxidos/metabolismo , Substâncias Protetoras/farmacologia , Pseudomonas/metabolismo , Espécies Reativas de Oxigênio/química , Espécies Reativas de Oxigênio/metabolismo , Pele , Solubilidade , Protetores Solares/metabolismo , Raios Ultravioleta
20.
Environ Geochem Health ; 43(5): 2065-2080, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33392897

RESUMO

This paper attempts to evaluate the mineralogical and chemical composition of sedimentary limestone mine waste alongside its mineral carbonation potential. The limestone mine wastes were recovered as the waste materials after mining and crushing processes and were analyzed for mineral, major and trace metal elements. The major mineral composition discovered was calcite (CaCO3) and dolomite [CaMg(CO3)2], alongside other minerals such as bustamite [(Ca,Mn)SiO3] and akermanite (Ca2MgSi2O7). Calcium oxide constituted the greatest composition of major oxide components of between 72 and 82%. The presence of CaO facilitated the transformation of carbon dioxide into carbonate form, suggesting potential mineral carbonation of the mine waste material. Geochemical assessment indicated that mean metal(loid) concentrations were found in the order of Al > Fe > Sr > Pb > Mn > Zn > As > Cd > Cu > Ni > Cr > Co in which Cd, Pb and As exceeded some regulatory guideline values. Ecological risk assessment demonstrated that the mine wastes were majorly influenced by Cd as being classified having moderate risk. Geochemical indices depicted that Cd was moderately accumulated and highly enriched in some of the mine waste deposited areas. In conclusion, the limestone mine waste material has the potential for sequestering CO2; however, the presence of some trace metals could be another important aspect that needs to be considered. Therefore, it has been shown that limestone mine waste can be regarded as a valuable feedstock for mineral carbonation process. Despite this, the presence of metal(loid) elements should be of another concern to minimize potential ecological implication due to recovery of this waste material.


Assuntos
Carbonato de Cálcio , Resíduos Industriais/análise , Mineração , Carbonato de Cálcio/análise , Compostos de Cálcio/análise , Compostos de Cálcio/química , Dióxido de Carbono/química , Carbonatos/análise , Carbonatos/química , Monitoramento Ambiental , Poluição Ambiental , Magnésio/análise , Malásia , Metais Pesados/análise , Minerais/análise , Óxidos/análise , Óxidos/química , Oligoelementos/análise
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