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1.
Sci Rep ; 14(1): 8701, 2024 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-38622193

RESUMO

Honey bees are social insects, and each colony member has unique morphological and physiological traits associated with their social tasks. Previously, we identified a long non-coding RNA from honey bees, termed Nb-1, whose expression in the brain decreases associated with the age-polyethism of workers and is detected in some neurosecretory cells and octopaminergic neurons, suggesting its role in the regulation of worker labor transition. Herein, we investigated its spatially and temporary-regulated/sex-specific expression. Nb-1 was expressed as an abundant maternal RNA during oogenesis and embryogenesis in both sexes. In addition, Nb-1 was expressed preferentially in the proliferating neuroblasts of the mushroom bodies (a higher-order center of the insect brain) in the pupal brains, suggesting its role in embryogenesis and mushroom body development. On the contrary, Nb-1 was expressed in a drone-specific manner in the pupal and adult retina, suggesting its role in the drone visual development and/or sense. Subcellular localization of Nb-1 in the brain during development differed depending on the cell type. Considering that Nb-1 is conserved only in Apidae, our findings suggest that Nb-1 potentially has pleiotropic functions in the expression of multiple developmental, behavioral, and physiological traits, which are closely associated with the honey bee lifecycle.


Assuntos
RNA Longo não Codificante , Feminino , Masculino , Abelhas/genética , Animais , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Nióbio , Encéfalo/fisiologia , Neurônios/fisiologia , Cabeça , Pupa
2.
J Appl Oral Sci ; 32: e20230278, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38537028

RESUMO

OBJECTIVE: The present in vitro study incorporated niobium oxyhydroxide fillers into an experimental high-viscosity bulk-fill resin composite to improve its mechanical performance and provide it a bioactive potential. METHODOLOGY: Scanning electron microscopy synthesized and characterized 0.5% niobium oxyhydroxide fillers, demonstrating a homogeneous morphology that represented a reinforcement for the feature. Fillers were weighed, gradually added to the experimental resin composite, and homogenized for one minute, forming three groups: BF (experimental high-viscosity bulk-fill resin composite; control), BF0.5 (experimental high-viscosity bulk-fill resin composite modified with 0.5% niobium oxyhydroxide fillers), and BFC (commercial bulk-fill resin composite Beautifil Bulk U, Shofu; positive control). In total, 10 specimens/groups (8 × 2 × 2 mm) underwent flexural strength (FS) tests in a universal testing machine (Instron) (500N). Resin composites were also assessed for Knoop hardness (KH), depth of cure (DoC), degree of conversion (DC), elastic modulus (E), and degree of color change (ΔE). The bioactive potential of the developed resin composite was evaluated after immersing the specimens into a simulated body fluid in vitro solution and assessing them using a Fourier-transformed infrared spectroscope with an attenuated total reflectance accessory. One-way ANOVA, followed by the Tukey's test (p<0.05), determined FS, DC, KH, and ΔE. For DoC, ANOVA was performed, which demonstrated no significant difference between groups (p<0.05). CONCLUSIONS: The high-viscosity bulk-fill resin composite with 0.5% niobium oxyhydroxide fillers showed promising outcomes as reinforcement agents and performed well for bioactive potential, although less predictable than the commercial resin composite with Giomer technology.


Assuntos
Resinas Compostas , Nióbio , Viscosidade , Teste de Materiais , Polimerização , Materiais Dentários
3.
Int J Mol Sci ; 25(5)2024 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-38473867

RESUMO

Nb-based catalysts supported on porous silica with different textural properties have been synthesized, characterized, and tested in the one-pot reaction of furfural to obtain valuable chemicals. The catalytic results reveal that the presence of fluoride in the synthesis, which limits the growing of the porous silica, limits diffusional problems of the porous silica, obtaining higher conversion values at shorter reaction times. On the other hand, the incorporation of NbOx species in the porous silica provides Lewis acid sites and a small proportion of Brönsted acid sites, in such a way that the main products are alkyl furfuryl ethers, which can be used as fuel additives.


Assuntos
Furaldeído , Nióbio , Furaldeído/química , Hidrogenação , Dióxido de Silício/química , Catálise
4.
Int J Mol Sci ; 25(5)2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38474252

RESUMO

Na-V-P-Nb-based materials have gained substantial recognition as cathode materials in high-rate sodium-ion batteries due to their unique properties and compositions, comprising both alkali and transition metal ions, which allow them to exhibit a mixed ionic-polaronic conduction mechanism. In this study, the impact of introducing two transition metal oxides, V2O5 and Nb2O5, on the thermal, (micro)structural, and electrical properties of the 35Na2O-25V2O5-(40 - x)P2O5 - xNb2O5 system is examined. The starting glass shows the highest values of DC conductivity, σDC, reaching 1.45 × 10-8 Ω-1 cm-1 at 303 K, along with a glass transition temperature, Tg, of 371 °C. The incorporation of Nb2O5 influences both σDC and Tg, resulting in non-linear trends, with the lowest values observed for the glass with x = 20 mol%. Electron paramagnetic resonance measurements and vibrational spectroscopy results suggest that the observed non-monotonic trend in σDC arises from a diminishing contribution of polaronic conductivity due to the decrease in the relative number of V4+ ions and the introduction of Nb2O5, which disrupts the predominantly mixed vanadate-phosphate network within the starting glasses, consequently impeding polaronic transport. The mechanism of electrical transport is investigated using the model-free Summerfield scaling procedure, revealing the presence of mixed ionic-polaronic conductivity in glasses where x < 10 mol%, whereas for x ≥ 10 mol%, the ionic conductivity mechanism becomes prominent. To assess the impact of the V2O5 content on the electrical transport mechanism, a comparative analysis of two analogue series with varying V2O5 content (10 and 25 mol%) is conducted to evaluate the extent of its polaronic contribution.


Assuntos
Nióbio , Fosfatos , Fosfatos/química , Vidro/química , Íons , Espectroscopia de Ressonância de Spin Eletrônica , Sódio/química , Cerâmica/química
5.
Dent Mater J ; 43(2): 216-226, 2024 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-38417860

RESUMO

This study aimed to investigate the effects of sandblasting on the physical properties and bond strength of two types of translucent zirconia: niobium-oxide-containing yttria-stabilized tetragonal zirconia polycrystals ((Y, Nb)-TZP) and 5 mol% yttria-partially stabilized zirconia (5Y-PSZ). Fully sintered disc specimens were either sandblasted with 125 µm alumina particles or left as-sintered. Surface roughness, crystal phase compositions, and surface morphology were explored. Biaxial flexural strength (n=10) and shear bond strength (SBS) (n=12) were evaluated, including thermocycling conditions. Results indicated a decrease in flexural strength of 5Y-PSZ from 601 to 303 MPa upon sandblasting, while (Y, Nb)-TZP improved from 458 to 544 MPa. Both materials significantly increased SBS after sandblasting (p<0.001). After thermocycling, (Y, Nb)-TZP maintained superior SBS (14.3 MPa) compared to 5Y-PSZ (11.3 MPa) (p<0.001). The study concludes that (Y, Nb)-TZP is preferable for sandblasting applications, particularly for achieving durable bonding without compromising flexural strength.


Assuntos
Materiais Dentários , Nióbio , Óxidos , Materiais Dentários/química , Teste de Materiais , Propriedades de Superfície , Zircônio/química , Ítrio/química , Óxido de Alumínio , Resistência ao Cisalhamento
6.
Nature ; 627(8002): 80-87, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38418888

RESUMO

Integrated microwave photonics (MWP) is an intriguing technology for the generation, transmission and manipulation of microwave signals in chip-scale optical systems1,2. In particular, ultrafast processing of analogue signals in the optical domain with high fidelity and low latency could enable a variety of applications such as MWP filters3-5, microwave signal processing6-9 and image recognition10,11. An ideal integrated MWP processing platform should have both an efficient and high-speed electro-optic modulation block to faithfully perform microwave-optic conversion at low power and also a low-loss functional photonic network to implement various signal-processing tasks. Moreover, large-scale, low-cost manufacturability is required to monolithically integrate the two building blocks on the same chip. Here we demonstrate such an integrated MWP processing engine based on a 4 inch wafer-scale thin-film lithium niobate platform. It can perform multipurpose tasks with processing bandwidths of up to 67 GHz at complementary metal-oxide-semiconductor (CMOS)-compatible voltages. We achieve ultrafast analogue computation, namely temporal integration and differentiation, at sampling rates of up to 256 giga samples per second, and deploy these functions to showcase three proof-of-concept applications: solving ordinary differential equations, generating ultra-wideband signals and detecting edges in images. We further leverage the image edge detector to realize a photonic-assisted image segmentation model that can effectively outline the boundaries of melanoma lesion in medical diagnostic images. Our ultrafast lithium niobate MWP engine could provide compact, low-latency and cost-effective solutions for future wireless communications, high-resolution radar and photonic artificial intelligence.


Assuntos
Micro-Ondas , Nióbio , Óptica e Fotônica , Óxidos , Fótons , Inteligência Artificial , Diagnóstico por Imagem/instrumentação , Diagnóstico por Imagem/métodos , Melanoma/diagnóstico por imagem , Melanoma/patologia , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Radar , Tecnologia sem Fio , Humanos
7.
J Biomed Mater Res B Appl Biomater ; 112(1): e35357, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38247242

RESUMO

To improve the wear resistance of articulating metallic joint endoprostheses, the surfaces can be coated with titanium niobium nitride (TiNbN). Under poor tribological conditions or malalignment, wear can occur on these implant surfaces in situ. This study investigated the biological response of human osteoblasts to wear particles generated from TiNbN-coated hip implants. Abrasive particles were generated in a hip simulator according to ISO 14242-1/-2 and extracted with Proteinase K. Particle characteristics were evaluated by electron microscopy and energy dispersive x-ray spectroscopy (EDS), inductively coupled plasma mass spectrometry (ICP-MS) and dynamic light scattering (DLS) measurements. Human osteoblasts were exposed to different particle dilutions (1:20, 1:50, and 1:100), and cell viability and gene expression levels of osteogenic markers and inflammatory mediators were analyzed after 4 and 7 days. Using ICP-MS, EDS, and DLS measurements, ~70% of the particles were identified as TiNbN, ranging from 39 to 94 nm. The particles exhibited a flat and subangular morphology. Exposure to particles did not influence cell viability and osteoblastic differentiation capacity. Protein levels of collagen type 1, osteoprotegerin, and receptor activator of nuclear factor κB ligand were almost unaffected. Moreover, the pro-inflammatory response via interleukins 6 and 8 was minor induced after particle contact. A high number of TiNbN wear particles only slightly affected osteoblasts' differentiation ability and inflammatory response compared to metallic particles. Nevertheless, further studies should investigate the role of these particles in peri-implant bone tissue, especially concerning other cell types.


Assuntos
Próteses Articulares Metal-Metal , Nióbio , Titânio , Humanos , Metais , Osteoblastos , Osso e Ossos
8.
J Environ Sci Health B ; 59(2): 50-61, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38054847

RESUMO

In this work, a comparison was made between the synthesis of niobium-based materials (Nb2O5), both in terms of material characterization and catalytic performance. The methods used were chemical mixtures: modified sol-gel and Pechini. The materials were calcined at different temperatures (753, 873 and 993K) and characterized by the following techniques: photoacousticspectroscopy (PAS), zero charge point (pHPZC), scanning electron microscopy (SEM/EDS), thermogravimetric analysis (TGA/DTG) and X-ray diffraction (XRD). The photocatalytic process was carried out to evaluate the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under UV radiation (250 W mercury vapor lamp) and different experimental conditions. In addition, to better understand the influence of parameters such as pH, catalyst concentration (0.2, 0.5 and 0.8 g L-1) and calcination temperature, a Design of Experiments (DoE) was used. The results indicated that despite having similar structures and phases in the XRD analysis, the morphology presents two distinct surfaces, due to the preparation method. Differences in the synthesis method affected the catalytic activity in the parameters studied. Although the zero charge point values are close (6.18-6.36), we observed differences in the band gap depending on the calcination temperature. In the optimal condition studied, the catalyst prepared by the sol-gel method obtained the best results.


Assuntos
Herbicidas , Nióbio/química , Raios Ultravioleta , Microscopia Eletrônica de Varredura , Ácido 2,4-Diclorofenoxiacético
9.
Nat Prod Res ; 38(1): 103-111, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-35929965

RESUMO

ABSTACTA chemical investigation of the endophyte Penicillium sp. Nb 19, isolated from leaves of the traditionally medical plant Baphicacanthus cusia (Nees) Bremek., yielded one new indole diterpenoid, 7-methoxy-13-dehydroxypaxilline (1) together with seven known metabolites (2-8). The obtained structure of compound 1 was elucidated by its spectroscopic data. In addition, the absolute configuration of compound 6 was confirmed by ECD for the first time. Compounds 1-6 were evaluated for antitumor activity against MCF-7, HepG2, and HCCC-9810 cell lines.


Assuntos
Diterpenos , Penicillium , Nióbio/metabolismo , Diterpenos/química , Fungos , Indóis/química , Penicillium/química , Estrutura Molecular
10.
J Environ Sci (China) ; 138: 450-457, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38135410

RESUMO

Hydrothermal stability is crucial for the practical application of deNOx catalyst on diesel vehicles, for the selective catalytic reduction of NOx with NH3 (NH3-SCR). SnO2-based materials possess superior hydrothermal stability, which is attractive for the development of NH3-SCR catalyst. In this work, a series of Ce-Nb/SnO2 catalysts, with Ce and Nb loading on SnO2 support, were prepared by impregnation method. It was found that, the NH3-SCR activities and hydrothermal stabilities of the Ce-Nb/SnO2 catalysts significantly varied with the impregnation sequences, and the Ce-Nb(f)/SnO2 catalyst that firstly impregnated Nb and then impregnated Ce exhibited the best performance. The characterization results revealed that Ce-Nb(f)/SnO2 possessed appropriate acidity and redox capability. Furthermore, the strong synergistic effect between Nb and Sn species stabilized the structure and maintained the dispersion of acid sites. This study may provide a new understanding for the effect of impregnation sequence on activity and hydrothermal stability and a new environmental-friendly NH3-SCR catalyst with potential applications for NOx removal from diesel and hydrogen-fueled engines.


Assuntos
Amônia , Nióbio , Amônia/química , Oxirredução , Hidrogênio , Catálise
11.
J Hematol Oncol ; 16(1): 115, 2023 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-38031188

RESUMO

BACKGROUND: T cell engagers (TCEs) have been established as an emerging modality for hematologic malignancies, but solid tumors remain refractory. However, the upregulation of programmed cell death 1 (PD-1) is correlated with T cell dysfunction that confer tumor-mediated immunosuppression. Developing a novel nanobody-based trispecific T cell engager (Nb-TriTE) would be a potential strategy to improve therapeutic efficacy. METHODS: Given the therapeutic potential of nanobodies (Nbs), we first screened Nb targeting fibroblast activation protein (FAP) and successfully generated a Nb-based bispecific T cell engager (Nb-BiTE) targeting FAP. Then, we developed a Nb-TriTE by fusing an anti-PD-1 Nb to the Nb-BiTE. The biological activity and antitumor efficacy of the Nb-TriTE were evaluated in vitro and in both cell line-derived and patient-derived xenograft mouse models. RESULTS: We had for the first time successfully selected a FAP Nb for the generation of novel Nb-BiTE and Nb-TriTE, which showed good binding ability to their targets. Nb-TriTE not only induced robust tumor antigen-specific killing, potent T cell activation and enhanced T cell function in vitro, but also suppressed tumor growth, improved survival and mediated more T cell infiltration than Nb-BiTE in mouse models of different solid tumors without toxicity. CONCLUSIONS: This novel Nb-TriTE provides a promising and universal platform to overcome tumor-mediated immunosuppression and improve patient outcomes in the future.


Assuntos
Anticorpos Biespecíficos , Neoplasias , Humanos , Camundongos , Animais , Nióbio/metabolismo , Neoplasias/terapia , Terapia de Imunossupressão , Linfócitos T , Tolerância Imunológica , Anticorpos Biespecíficos/farmacologia , Anticorpos Biespecíficos/uso terapêutico , Anticorpos Biespecíficos/metabolismo
12.
Environ Sci Pollut Res Int ; 30(58): 122458-122469, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37973783

RESUMO

Polyethyleneimine (PEI) capping agent-cum-template-mediated synthesis of niobium oxide nanoparticles is reported to explore its impact on the resultant morphology, porosity, crystallinity, phase complexation, and thus on the photocatalytic activity. The resultant niobium oxides calcined at 800°C and 1000°C crystallized into highly ordered nano-rod/tripod nanostructure with inter-rod angle <120° having orthorhombic phase and heavily agglomerated rod-like nanostructures having monoclinic crystal phase, respectively. Contrary to the expectations, the nano-rod/tripods showed superior photocatalytic degradation kinetics and high adsorption of methylene blue dye in the hydrocolloid than formerly reported monoclinic nanoparticles. The best adsorption capability and photocatalytic activity are observed for the sample calcined at 800°C, resulting in a combined degradation efficiency of 98.8% of methylene blue dye. The adsorption characteristics, stability of the hydrocolloid system, the existence of oxygen vacancies, and the distinct morphology of the photocatalytic nano-rod/tripods are mainly responsible for this behavior. The process and the performance of unique nanostructure over others presents a superior alternative.


Assuntos
Azul de Metileno , Nióbio , Azul de Metileno/química , Polietilenoimina , Óxidos/química , Coloides
13.
Environ Sci Technol ; 57(43): 16685-16694, 2023 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-37864569

RESUMO

Selective catalytic reduction of NOx by NH3 (NH3-SCR) for diesel emission control at low temperatures is still a great challenge due to the limit of the urea injection threshold and inferior SCR activity of state-of-the-art catalyst systems below 200 °C. Fabricating bifunctional catalysts with both low temperature NOx adsorption-storage capacity and medium-high temperature NOx reduction activity is an effective strategy to solve the issues mentioned above but is rarely investigated. Herein, the WO3/Ce0.68Zr0.32Ox (W/CZ) catalyst containing the κ-Ce2Zr2O8 pyrochlore structure was successfully developed by a simple H2 reduction method, not only showing superior NOx adsorption-storage ability below 180 °C but also exhibiting excellent NH3-SCR activity above 180 °C. The presence of the pyrochlore structure effectively increased the oxygen vacancies on the κ-Ce2Zr2O8-containing W/CZ catalyst with enhanced redox property, which significantly promoted the NOx adsorption-storage as active nitrate species below 180 °C. Upon NH3 introduction above 180 °C, the κ-Ce2Zr2O8-containing W/CZ catalyst showed greatly improved NOx reduction performance, suggesting that the pyrochlore structure played a vital role in improving the NOx adsorption-selective catalytic reduction (AdSCR) performance. This work provides a new perspective for designing bifunctional CeZrOx-based catalysts to efficiently control the NOx emissions from diesel engines during the cold-start process.


Assuntos
Amônia , Nióbio , Adsorção , Amônia/química , Oxirredução , Catálise
14.
Biosens Bioelectron ; 242: 115725, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-37837938

RESUMO

Rapid and accurate on-site detection of aflatoxin B1 (AFB1) is of great significance for ensuring food safety. This work developed a dual mode aptasensor and a dual channel artificial neural network (ANN) intelligent sensor detection platform for simple and convenient quantitative detection of AFB1 in food. This sensor was prepared by encoding manganese ion (Mn2+) mediated surface concave niobium carbide MXene nanomaterials (Nb2C-MNs) using fluorescent group labeled aptamers (ssDNA-FAM). Mn2+-mediated Nb2C-MNs exhibited better peroxidase-like and fluorescence quenching properties. Moreover, ssDNA-FAM as a fluorescent probe for the sensor also significantly enhanced the enzyme activity of Nb2C-MNs. When AFB1 existed, ssDNA-FAM preferentially bonded to AFB1, resulting in fluorescence signal recovery and colorimetric signal weakening. Consequently, the multimodal biosensor could achieve fluorescence/colorimetric detection without the need for material and reagent replacement. In on-site detection, both ratio fluorescence and colorimetric signals could be collected using smartphones and analyzed and modeled on the developed ANN platform, achieving visual intelligent sensing. This multimodal biosensor had a detection line as low as 0.0950 ng/mL under optimal conditions, and also had the advantages of simple operation, fast and sensitive, and high specificity, which can meet the real-time on-site detection needs of AFB1 in remote areas.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Técnicas Biossensoriais/métodos , Nióbio , Corantes Fluorescentes , Aflatoxina B1/análise , DNA de Cadeia Simples , Limite de Detecção
16.
Environ Sci Pollut Res Int ; 30(47): 103731-103742, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37688700

RESUMO

The development of effective photocatalytic materials is essential for removing emerging pollutants from aqueous media, such as the hormone 17ß-estradiol (E2). In this study, a novel photocatalyst based on niobium pentoxide (Nb2O5) functionalized with nickel (Ni) and copper (Cu) was synthesized for E2 removal. The NiCu/Nb2O5 photocatalyst was prepared using a facile wet impregnation method and characterized by various techniques. The incorporation of Ni and Cu into Nb2O5 reduced the band gap energy from 3.3 to 2.8 eV, enabling efficient utilization of visible light. Moreover, NiCu/Nb2O5 exhibited the highest E2 removal efficiency (82%) under UV-A-assisted conditions at a concentration of 1.5 g L-1. The reaction kinetics were found to follow a second-order model with a rate constant of k = 0.0020 L g-1 min-1, and a plausible reaction mechanism was proposed. Through the study of radical elimination, it was proven that the radical oxidation reaction mechanism predominated in the reaction. The results of the toxicity assays, combined with the TOC parameter, demonstrated the efficacy of photocatalytic degradation in reducing E2. These findings demonstrate the great potential of the NiCu/Nb2O5 photocatalyst for removing persistent pollutants.


Assuntos
Poluentes Químicos da Água , Água , Nióbio , Oxirredução , Luz , Catálise , Níquel
17.
Chemosphere ; 341: 140006, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37683948

RESUMO

Biochar-based supported denitration catalysts have shown tremendous potential in reducing NOx, while improving low-temperature NH3-SCR catalytic activity and SO2 tolerance still faces great challenges. In this work, Mn7-Cu3/BCN and Mn7-Cu3-Nbx/BCN catalysts were prepared by one-step wet impregnation. The enhanced effect of Nb doping on the catalytic performance and SO2 tolerance over the Mn7-Cu3/BCN catalyst was evaluated in the temperature range of 75-275 °C. The denitrification activity test showed that the introduction of an appropriate amount of Nb increased the catalytic activity and N2 selectivity of the catalyst. The NO conversion of Mn7-Cu3-Nb0.05/BCN with an optimum doping ratio of 0.05 wt% Nb was higher than 94% at 150-275 °C. The characterization results indicated that the introduction of Nb enhanced the interaction between the active components MnOx and CuOx, accelerated the electron transfer between elements, and thus improved the Mn4+/Mnn+ and Oα/(Oα+Oß+Oγ) proportions and redox performance. On the other hand, Nb modification increased the number of weakly acidic sites, which was beneficial for the adsorption and activation of the reducing agent NH3 under low-temperature conditions. Meanwhile, Nb could significantly improve the SO2 poisoning resistance of the Mn7-Cu3/BCN-S catalyst when SO2 was added to the reaction system. The NO conversion of Mn7-Cu3-Nb0.05/BCN remained above 75% after a 13.5 h reaction under 100 ppm SO2 and 5 vol% H2O at 225 °C. By combining experimental characterization results with DFT calculation results, we effectively confirmed that Mn7-Cu3-Nb0.05/BCN had good sulfur resistance, mainly because Nb could effectively inhibit the formation of manganese sulfate and promote the decomposition of ammonium bisulfate.


Assuntos
Temperatura Baixa , Nióbio , Temperatura , Adsorção , Catálise
18.
Sci Rep ; 13(1): 16045, 2023 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-37749260

RESUMO

NiTi is a class of metallic biomaterials, benefit from superelastic behavior, high biocompatibility, and favorable mechanical properties close to that of bone. However, the Ni ion leaching, poor bioactivity, and antibacterial activity limit its clinical applications. In this study, HAp-Nb2O5 composite layers were PC electrodeposited from aqueous electrolytes containing different concentrations of the Nb2O5 particles, i.e., 0-1 g/L, to evaluate the influence of the applied surface engineering strategy on in vitro immersion behavior, Ni2+ ion leaching level, and antibacterial activity of the bare NiTi. Surface characteristics of the electrodeposited layers were analyzed using SEM, TEM, XPS, and AFM. The immersion behavior of the samples was comprehensively investigated through SBF and long-term PBS soaking. Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) infective reference bacteria were employed to address the antibacterial activity of the samples. The results illustrated that the included particles led to more compact and smoother layers. Unlike bare NiTi, composite layers stimulated apatite formation upon immersion in both SBF and PBS media. The concentration of the released Ni2+ ion from the composite layer, containing 0.50 g/L Nb2O5 was ≈ 60% less than that of bare NiTi within 30 days of immersion in the corrosive PBS solution. The Nb2O5-reinforced layers exhibited high anti-adhesive activity against both types of pathogenic bacteria. The hybrid metallic-ceramic system comprising HAp-Nb2O5-coated NiTi offers the prospect of a potential solution for clinical challenges facing the orthopedic application of NiTi.


Assuntos
Materiais Biocompatíveis , Escherichia coli , Materiais Biocompatíveis/farmacologia , Staphylococcus aureus , Imersão , Nióbio , Antibacterianos/farmacologia , Propriedades de Superfície , Titânio/farmacologia , Teste de Materiais
19.
Biomater Adv ; 153: 213581, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37572598

RESUMO

Two-dimensional (2D) transition metal carbides/nitrides (MXenes) are potential antibacterial agents. However, their activity against microorganisms is not fully understood. It could relate to MXenes' surface which further influences their biocidal action. Herein, we report no continuous biocidal activity for delaminated 2D niobium-based MXenes (Nbn+1XnTx) such as Nb2CTx and Nb4C3Tx prepared with HF/TMAOH protocol. Biocidal activity towards Bacillus subtilis and Staphylococcus aureus microorganisms was achieved by surface-functionalization with lysozyme macromolecule. MXenes' engineering with lysozyme changed MXene's surface charge from negative into positive thus enabling the elimination of bacteria cells during 48 h of incubation. In contrast, Nb4C3Tx functionalized with collagen stimulated the growth of Bacillus subtilis by 225 %, showing MXene's biocompatibility towards this particular strain. Altogether, our results show that MXenes are incredibly bio-tunable. Opposing bio-effects such as antimicrobial or growth-stimulating can be achieved towards various microorganisms with rational surface engineering.


Assuntos
Muramidase , Nióbio , Antibacterianos/farmacologia , Bacillus subtilis
20.
Molecules ; 28(13)2023 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-37446574

RESUMO

The reactions between catechol (H2cat) and niobium(V) or tantalum(V) precursors in basic aqueous solutions lead to the formation of catecholate complexes of different natures. The following complexes were isolated and characterized by single-crystal X-ray diffraction (SCXRD): (1) (NH4)3[NbO(cat)3]∙4H2O; (2) K2[Nb(cat)3(Hcat)]·2H2cat·2H2O; (3) Cs3[NbO(cat)3]·H2O; (4) (NH4)4[Ta2O(cat)6]·3H2O; (5) Cs2[Ta(cat)3(Hcat)]·H2cat; (6) Cs4[Ta2O(cat)6]·7H2O. The isolated crystalline products were characterized by elemental analysis, X-ray powder diffraction (XRPD), FTIR, and TGA. The structural features of these complexes, such as {Ta2O} unit geometry, Cs-π interactions, and crystal packing effects, are discussed.


Assuntos
Nióbio , Tantálio , Nióbio/química , Tantálio/química , Cristalografia por Raios X
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