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1.
Chemosphere ; 251: 126382, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32443238

RESUMO

A single metal Pd/γ-Al2O3 catalyst and a bimetallic Pd-Ce/γ-Al2O3 catalyst were prepared by the equal-volume impregnation method to investigate the effect of CeO2 loading on the catalytic oxidation of toluene. The specific surface area, surface morphology, and redox performance of the catalyst were characterized by N2 desorption, scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), H2-TPR, O2-TPD, and electron paramagnetic resonance (EPR). The results showed that bimetal catalysts loaded CeO2 had smaller nano-PdO particles than those of the Pd/γ-Al2O3 catalyst. Compared with the catalyst of 0.2Pd/γ-Al2O3 (percentage of mass, the same as below), the catalyst doped with 0.3CeO2 had a stronger reduction peak, which was shifted to the low-temperature zone by more than 80 °C. The results of XPS and O2-TPD showed that the introduction of CeO2 provided more surface oxygen vacancy for the catalyst and enhanced its catalytic oxidation ability, and the amount of desorbed O2 increased from 3.55 µmol/g to 8.54 µmol/g. The results of EPR were that the addition of CeO2 increased the content of active oxygen species and oxygen vacancies on the surface of the catalysts, which might be due to the supply of electrons to the O2 and PdO during the Ce3+toCe4+ conversion process. That could have accelerated the catalytic reaction process. Compared with the single precious metal catalyst, the T10 and T90 of the Pd-Ce/γ-Al2O3 catalyst were decreased by 22 °C and 40 °C, respectively.


Assuntos
Tolueno/química , Óxido de Alumínio/química , Catálise , Cério/química , Chumbo/química , Oxirredução , Oxigênio/química , Espectroscopia Fotoeletrônica
2.
Chemosphere ; 256: 127077, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32438124

RESUMO

The ultra-deep adsorptive desulfurization (ppb level) of benzene remains a challenging subject with the need to construct efficient adsorbent systems. Herein, a kind of ruthenium-based adsorbent functionalized with bimetallic Ru-Al was rationally designed using Al2O3 as support (denoted as 0.8%Ru-1.2%Al/Al2O3). It was found that the co-anchoring of Ru and Al species endows the Ru-based adsorbent unique adsorption capability, which is able to completely eliminate sulfur compounds in benzene, and exhibiting a much higher breakthrough sulfur capacity than that of the 0.8%Ru/Al2O3. Remarkably, under the industrial experiment conditions, 0.8%Ru-1.2%Al/Al2O3 exhibited excellent long-term stability for more than 1200 h, showing the potential for industrial application. Various characterization techniques, including BET, XRD, SEM, TEM, TPD-MS, TPR and XPS, were used to investigate the correlation between the adsorption performance and the microstructure of the adsorbents. Over 0.8%Ru-1.2%Al/Al2O3, the ultra-thin aluminum additive is beneficial to improve the dispersion of Ru species, which therefore exhibits desirable desulfurization efficiency. Moreover, the enhanced performance is also correlated to the presence of the suitable Ru active centers generated from the selective coverage by Al species. It leads to an optimal exposure of the Ru active centers, which would facilitate the interaction of S-Ru and the improvement of the desulfurization activity.


Assuntos
Benzeno/análise , Rutênio/química , Adsorção , Alumínio , Óxido de Alumínio/química , Espaços Confinados , Enxofre , Compostos de Enxofre
3.
Int J Nanomedicine ; 15: 1021-1035, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32103954

RESUMO

Background and Aim: We have previously identified ubiquitinated proteins (UPs) from tumor cell lysates as a promising vaccine for cancer immunotherapy in different mouse tumor models. In this study, we aimed at developing a highly efficient therapeutic adjuvant built-in nanovaccine (α-Al2O3-UPs) by a simple method, in which UPs from tumor cells could be efficiently and conveniently enriched by α-Al2O3 nanoparticles covalently coupled with Vx3 proteins (α-Al2O3-CONH-Vx3). Methods: The α-Al2O3 nanoparticles were modified with 4-hydroxybenzoic acid followed by coupling with ubiquitin-binding protein Vx3. It was then used to enrich UPs from 4T1 cell lysate. The stability and the efficiency for the UPs enrichment of α-Al2O3-CONH-Vx3 were examined. The ability of α-Al2O3-UPs to activate DCs was examined in vitro subsequently. The splenocytes from the vaccinated mice were re-stimulated with inactivated tumor cells, and the IFN-γ secretion was detected by ELISA and flow cytometry. Moreover, the therapeutic efficacy of α-Al2O3-UPs, alone and in combination with chemotherapy, was examined in 4T1 tumor-bearing mice. Results: Our results showed that α-Al2O3-UPs were successfully synthesized and abundant UPs from tumor cell lysate were enriched by the new method. In vitro study showed that compared to the physical mixture of α-Al2O3 nanoparticles and UPs (α-Al2O3+UPs), α-Al2O3-UPs stimulation resulted in higher upregulations of CD80, CD86, MHC class I, and MHC class II on DCs, indicating the higher ability of DC activation. Moreover, α-Al2O3-UPs elicited a more effective immune response in mice, demonstrated by higher IFN-γ secretion than α-Al2O3+UPs. Furthermore, α-Al2O3-UPs also exhibited a more potent effect on tumor growth inhibition and survival prolongation in 4T1 tumor-bearing mice. Notably, when in combination with low dose chemotherapy, the anti-tumor effect was further enhanced, rather than using α-Al2O3-UPs alone. Conclusion: This study presents an adjuvant built-in nanovaccine generated by a new simple method that can be potentially applied to cancer immunotherapy and lays the experimental foundation for future clinical application.


Assuntos
Vacinas Anticâncer/farmacologia , Nanopartículas/química , Proteínas Ubiquitinadas/química , Adjuvantes Imunológicos/farmacologia , Óxido de Alumínio/química , Animais , Vacinas Anticâncer/imunologia , Linhagem Celular Tumoral , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/imunologia , Feminino , Interferon gama/metabolismo , Camundongos Endogâmicos BALB C , Nanopartículas/uso terapêutico , Neoplasias Experimentais/terapia , Parabenos/química , Proteínas Ubiquitinadas/imunologia
4.
J Appl Oral Sci ; 28: e20190371, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049135

RESUMO

OBJECTIVE: This study aims to evaluate the influence of different air-abrasion pressures and subsequent heat treatment on the flexural strength, surface roughness, and crystallographic phases of highly translucent partially stabilized zirconia (Y-PSZ), and on the tensile bond strength of resin cement to Y-PSZ. METHODOLOGY: Fully sintered zirconia specimens were ground with SiC paper (control) and/or air-abraded with 50 µm particles of alumina at 0.1, 0.15, 0.2, or 0.3 MPa or left as-sintered. After air-abrasion at 0.2 MPa (0.2AB), additional specimens were then heated to 1500°C, and held for one hour at this temperature (0.2AB+HT1h). Flexural strength and surface roughness were evaluated. Crystalline phase identification was also carried out using X-ray diffraction. Bonded zirconia specimens with self-adhesive resin cement were stored in distilled water at 37°C for 24 h, either with or without aging (thermal cycling 4-60°C/20000). Results were analyzed statistically by ANOVA and Tukey-Kramer tests. RESULTS: The flexural strength decreased with the increase in air-abrasion pressure, while in contrast, the surface roughness increased. The lowest flexural strength and the highest roughness value were found for the 0.2AB and 0.3AB groups, respectively. All groups contained cubic-, tetragonal ( t )-, and rhombohedral ( r )-ZrO2 phases with the exception of the as-sintered group. Upon increasing the air-abrasion pressure, the relative amount of the r -ZrO2 phase increased, with a significant amount of r -ZrO2 phase being detected for the 0.2AB and 0.3AB groups. The 0.2AB+HT1h group exhibited a similar flexural strength and t -ZrO2 phase content as the as-sintered group. However, the 0.2AB group showed a significantly higher tensile bond strength (p<0.05) than the 0.2AB+HT1h group before and after aging. CONCLUSION: Micromechanical retention by alumina air-abrasion at 0.2 MPa, in combination with chemical bonding of a resin to highly translucent Y-PSZ using a MDP-containing resin cement may enable durable bonding.


Assuntos
Abrasão Dental por Ar/métodos , Óxido de Alumínio/química , Colagem Dentária/métodos , Cimentos de Resina/química , Zircônio/química , Análise de Variância , Resistência à Flexão , Temperatura Alta , Teste de Materiais , Microscopia Confocal/métodos , Valores de Referência , Reprodutibilidade dos Testes , Propriedades de Superfície , Resistência à Tração , Difração de Raios X/métodos
5.
Chemosphere ; 247: 125863, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31972485

RESUMO

Plasma-catalysis technologies (PCTs) have the potential to control the emissions of volatile organic compounds, although their low-energy efficiency is a bottleneck for their practical applications. A plasma-catalyst reactor filled with a CeO2/γ-Al2O3 catalyst was developed to decompose toluene with a high-energy efficiency enhanced by the elevating reaction temperature. When the reaction temperature was raised from 50 °C to 250 °C, toluene conversion dramatically increased from 45.3% to 95.5% and the energy efficiency increased from 53.5 g/kWh to 113.0 g/kWh. Conversely, the toluene conversion using a thermal catalysis technology (TCT) exhibited a maximum of 16.7%. The activation energy of toluene decomposition using PCTs is 14.0 kJ/mol, which is far lower than those of toluene decomposition using TCTs, which implies that toluene decomposition using PCT differs from that using TCT. The experimental results revealed that the Ce3+/Ce4+ ratio decreased and Oads/Olatt ratio increased after the 40-h evaluation experiment, suggesting that CeO2 promoted the formation of the reactive oxygen species that is beneficial for toluene decomposition.


Assuntos
Poluentes Atmosféricos/análise , Gases em Plasma/química , Tolueno/análise , Compostos Orgânicos Voláteis/análise , Óxido de Alumínio/química , Catálise , Cério/química , Temperatura Alta , Modelos Teóricos , Oxirredução
6.
Chemosphere ; 242: 125244, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896184

RESUMO

Efficient wastewater restoration depends on the robustness and capability of the catalyst to promote sophisticated decontamination technologies. In this study, Co3Fe7-CoFe2O4 nanoparticles (NPs) prepared by facile pyrolysis were completely characterized and used to decompose 2,4-dichlorophenol (2,4-DCP). Furthermore, the catalytic performance and relevant mechanisms involved in the activation of peroxymonosulfate (PMS) were also investigated. The optimal conditions were achieved at the catalyst loading of 0.05 g L-1, PMS dosage of 1.26 g L-1, and pH of 7.7 through the response surface methodology by using the Box-Behnken design model. Under optimal conditions, 97.1% efficiency of 2,4-DCP removal was obtained within 30 min. Moreover, the quenching experiments and electron paramagnetic resonance result indicated that sulfate (SO4•-) and hydroxyl (HO•) radicals were considered as the dominant reactive oxygen species, which resulted in the effective removal of 2,4-DCP in the Co3Fe7-CoFe2O4/PMS system. Moreover, Co3Fe7-CoFe2O4 showed efficient catalytic performance in continuous five runs and exhibited less metal leaching of 0.052 and 0.036 mg L-1 for Co and Fe species, respectively. Furthermore, no considerable change was observed in the structural characteristics of the fresh and used Co3Fe7-CoFe2O4 catalytic system. The above-mentioned results indicated that the synergistic effects between Co3Fe7 alloy and CoFe2O4 spinel not only significantly improved the activity and long-term durability of the catalyst, but also accelerated the Co3+/Co2+ and Fe3+/Fe2+ redox cycles. Overall, the Co3Fe7-CoFe2O4/PMS system provides a novel advanced oxidation approach to further develop multifunctional transition metal-based nanomaterials responsible for producing surface-bound radicals and enhancing the remediation of refractory pollutants in the environmental application.


Assuntos
Óxido de Alumínio/química , Clorofenóis/química , Óxido de Magnésio/química , Peróxidos/química , Eliminação de Resíduos Líquidos/métodos , Ligas , Catálise , Nanopartículas/química , Oxirredução , Fenóis , Águas Residuárias
7.
Chemosphere ; 247: 125876, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31978652

RESUMO

Aluminium oxide nanoparticles (Al2O3 NPs) potentially cause health hazards after their release into the environment. The crystalline phase of Al2O3 NPs determines their surface structure and the number of functional groups. The adsorption of natural organic matter (NOM) or biomolecules on the surface Al2O3 NPs also alters their surface properties and subsequent interactions with organisms. In this study, the roles of the Al2O3 crystalline phase and the surface coating of the nanoparticles on the membrane integrity and fluidity were investigated. Giant and small unilamellar vesicles (GUVs and SUVs) were prepared as model cell membranes to detect membrane disruption after exposure to Al2O3 NPs. Due to amorphous structure and high surface activity of γ-Al2O3 NPs, they had a stronger affinity with the membrane and caused more serious membrane rupture than that of α-Al2O3 NPs. The deposition of Al2O3 NPs on the membrane and the induced membrane disruption were monitored by a quartz crystal microbalance with dissipation (QCM-D) method. HA-coated Al2O3 NPs disrupted the SUV layer on the QCM-D sensor, while BSA-coated Al2O3 NPs only adhered to the membrane and induced unremarkable vesicle disruption. In addition, untreated γ-Al2O3 NPs induced remarkable gelation of a negatively charged membrane, but other types of Al2O3 NPs caused negligible membrane phase changes. The outcomes of this study demonstrate that the crystalline phase of the Al2O3 NPs affects the integrity and fluidity of cell membranes. The protein coatings on the NPs weaken the NP-membrane interaction, while HA coatings increase the damage of the NP-induced interaction.


Assuntos
Óxido de Alumínio/química , Modelos Químicos , Nanopartículas/química , Adsorção , Membrana Celular , Coloides , Excipientes , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície
8.
Artigo em Inglês | MEDLINE | ID: mdl-31674277

RESUMO

1,1-Dimethylhydrazine (UDMH) and its by-products were considered carcinogenic toxins and represent a serious health hazard to the population once present in water under natural conditions without treatment. The conventional degradation method suffers from incomplete removal of intermediate products (especially N-nitrosodimethylamine (NDMA)), the powdery catalysis being difficult to recover and results in high energy consumption. In this study, a series of Bi2O3/TiO2/Al2O3 (BTA) photocatalysts have been successfully synthesized by a simple dry mixing method with powder material followed by their immobilization. It was evaluated by the photocatalytic degradation of UDMH present in wastewater, which can be recovered by rapid filtration and utilizes only solar energy. The catalyst exhibited markedly enhanced photocatalytic activity for the degradation of UDMH wastewater compared with conventional TiO2/Al2O3 (TA) catalysts under UV, visible and solar irradiation. Besides, the intermediate NDMA was gradually completely degraded. The photocatalysts were extensively characterized using scanning electron microscopy, energy dispersive spectrometry, specific surface area (BET), X-ray diffraction, X-ray photoelectron spectroscopy, UV-visible diffuse reflectance spectroscopy and photo-electrochemical I-t curves evaluation. The results revealed that all the BTA composites exhibited high stability and stronger absorbance in visible light. In addition, the BTA exhibited a reversible photochromic property that can effectively expand the range of light absorption and enhance the photocatalytic activity. The reversible photochromic properties of BTA explained in the proposed mechanism model are expected to be useful for detecting and sensing UDMH or other organic contaminants.


Assuntos
Óxido de Alumínio/química , Bismuto/química , Dimetilidrazinas/isolamento & purificação , Titânio/química , Poluentes Químicos da Água/isolamento & purificação , Catálise , Dimetilidrazinas/química , Dimetilnitrosamina/química , Dimetilnitrosamina/isolamento & purificação , Fotólise , Propriedades de Superfície , Poluentes Químicos da Água/química , Purificação da Água/métodos
9.
J Chromatogr A ; 1612: 460614, 2020 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-31668869

RESUMO

High radioactive concentration of 131I in the form of 131I[NaI] solution is essential for preparation of large-dose therapeutic capsules used in the management of thyroid cancer. In this communication, we report the synthesis of mesoporous alumina sorbent (surface area = 292 ±â€¯28 m2/g, mean pore diameter = 6.8 ±â€¯0.7 nm) by a novel solid state mechanochemical approach and its utilization in post-processing concentration of 131I. The overall yield of 131I after the concentration procedure was >90% and 131I[NaI] solution could be obtained with appreciably high (1.7 TBq/mL) radioactive concentration, suitable for use in nuclear medicine. The promising results obtained in this study would stimulate greater utilization of this new class of sorbents in sample preparations by solid phase extraction procedures for societal benefits.


Assuntos
Óxido de Alumínio/síntese química , Radioisótopos do Iodo/isolamento & purificação , Óxido de Alumínio/química , Humanos , Radioisótopos do Iodo/uso terapêutico , Extração em Fase Sólida/métodos , Neoplasias da Glândula Tireoide/radioterapia
10.
Sci Total Environ ; 704: 135414, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31810693

RESUMO

Efficient conversion of food waste to value-added products necessitates the development of high-performance heterogeneous catalysts. This study evaluated the use of Al2O3 as a low-cost and abundant support material for fabricating Lewis acid catalysts, i.e., through the in-situ doping of Cu, Ni, Co, and Zr into Al2O3 followed by calcination. The characterisation results show that all catalysts were mainly amorphous. In particular, adding the transition metals to the Al2O3 matrix resulted in the increase of acidity and meso-/micro-pores. The catalysts were evaluated in the conversion of glucose, which can be easily derived from starch-rich food waste (e.g., bread waste) via hydrolysis, to fructose in biorefinery. The results indicate that the Ni-doped Al2O3 (Al-Ni-C) achieved the highest fructose yield (19 mol%) and selectivity (59 mol%) under heating at 170 °C for 20 min, of which the performance falls into the range reported in literature. In contrast, the Zr-doped Al2O3 (Al-Zr-C) presented the lowest fructose selectivity despite the highest glucose conversion, meaning that the catalyst was relatively active towards the side reactions of glucose and intermediates. The porosity and acidity, modified via metal impregnation, were deduced as the determinants of the catalytic performance. It is noteworthy that the importance of these parameters may vary in a relative sense and the limiting factor could shift from one parameter to another. Therefore, evaluating physicochemical properties as a whole, instead of the unilateral improvement of a single parameter, is encouraged to leverage each functionality for cost-effectiveness. This study provides insights into the structure-performance relationships to promote advance in catalyst design serving a sustainable food waste biorefinery.


Assuntos
Óxido de Alumínio/química , Alimentos , Eliminação de Resíduos/métodos , Resíduos , Glucose , Concentração de Íons de Hidrogênio , Hidrólise , Metais/química , Porosidade
11.
Mater Sci Eng C Mater Biol Appl ; 107: 110314, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31761184

RESUMO

This review focuses on the biomedical applications and toxicity of spinel ferrite nanoparticles (SFNPs) with more emphasis on the recently published work. A critical review is provided on recent advances of SFNPs applications in biomedical areas. The novelty of SFNPs in addressing the bottleneck problems encountered in the areas of health; in particular, for diagnosis and treatment of tumour cells are well reviewed. Furthermore, research gaps, toxicity of SFNPs and areas which still need more attention are highlighted. Based on the result of this review, the SFNPs have unlimited capacity in cancer treatment, disease diagnosis, magnetic resonance imaging, drug delivery and release. Overall, stepping out of the conventional way of treatment is difficult but also essential in bringing long lasting solution for cancer and other diseases treatment. In fact, the toxicity study and commercialisation of the SFNPs based cancer treatment options are the main challenges and need further study, in order to reduce unforeseen consequences.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Hipertermia Induzida/métodos , Nanocompostos/química , Nanocompostos/uso terapêutico , Nanopartículas/química , Nanopartículas/uso terapêutico , Óxido de Alumínio/química , Animais , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/uso terapêutico , Compostos Férricos/química , Humanos , Óxido de Magnésio/química , Nanocompostos/toxicidade , Nanopartículas/toxicidade , Neoplasias/diagnóstico
12.
Colloids Surf B Biointerfaces ; 185: 110591, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31704606

RESUMO

Aluminium doped phosphate based bioglasses have potential applications in the field of bone tissue engineering, because of their excellent bioactivity and biocompatibility along with high mechanical strength and controlled dissolution. In the present study, 8ZnO-22Na2O-(24-x)CaO-46P2O5-xAl2O3 (where x = 0, 2, 4, 6, 8 and 10 mol%) glass system was synthesized and investigated by means of XRD, FTIR, SEM and EDS before and after immersion in SBF for 3, 7, 14 and 21days, the physic-chemical properties of the samples, including density and microhardness, evaluation of pH and weight loss of glasses in physiological fluid and cell cultural studies like cell viability, cytocompatability and cell proliferation by seeding rMSCs cells on the glass samples in order to throw some light on their structural properties. The results showed that, the density and Vickers hardness found to be increased with the increase in content of alumina due to the slight increase in the number of octahedrally coordinated Al3+ ions and stronger ionic cross linkages due to insertion of Al3+ ions between phosphate networks. The initial rise in pH and controlled solubility in SBF strongly supports the apatite layer development. The growth of the rMSCs cells on all samples showing good cytocompatability and proliferation up to 6 mol% Al2O3 after that decreases slightly with an increase in alumina content due to network forming action of Al3+ ions in zinc phosphate based glasses. The results confirmed the suitability of these glasses for clinical trials towards bone repair and regeneration resorbable implants.


Assuntos
Óxido de Alumínio/química , Materiais Biocompatíveis/farmacologia , Osso e Ossos/citologia , Cerâmica/química , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Fosfatos/química , Compostos de Zinco/química , Animais , Materiais Biocompatíveis/química , Osso e Ossos/efeitos dos fármacos , Sobrevivência Celular , Células Cultivadas , Células-Tronco Mesenquimais/efeitos dos fármacos , Ratos , Engenharia Tecidual
13.
Food Chem ; 307: 125528, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31648181

RESUMO

Simple, rapid, convenient, and economical surface enhanced Raman scattering (SERS) substrate is developed for on-site evaluation of Aflatoxin B1 (AFB1) in food matrix using handheld Raman Spectrometer. Self-assembly of gold nanobipyramids (Au NBPs) into the nanoholes of anodic aluminum oxide (AAO) template/pattern using 'drop-dry' approach provides a reliable pathway for the rapid fabrication of highly active and uniform SERS substrate. It shows enhanced and reproducible SERS signals towards the probe molecule, 4-aminothiophenol (4-ATP) with a relative standard deviation (RSD) of less than 10% and an average enhancement factor (EF) of 1 × 108. For practical application, the proposed method is demonstrated for the detection of aflatoxin B1 (AFB1) in peanut extracts. The results show that the AFB1 in peanut extracts can be identified within 1 min, with a limit of detection of 0.5 µg/L. Compared with conventional ELISA based AFB1 analysis, our method is much more efficient (1 min versus >30 min).


Assuntos
Aflatoxina B1/análise , Arachis/química , Nanoestruturas/química , Extratos Vegetais/química , Análise Espectral Raman/métodos , Óxido de Alumínio/química , Arachis/metabolismo , Ouro/química , Limite de Detecção
14.
Biosens Bioelectron ; 149: 111828, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31726275

RESUMO

The determination of cytochrome c in the human serum sample is a regular medical investigation performed to assess cancer diseases. Herein, we used interferometric reflectance spectroscopy (IRS) based biosensor for the determination of cytochrome c. For this purpose first, the nanoporous anodic alumina (NAA) was fabricated. Then, the NAA pore walls were functionalized with 3-aminopropyl trimethoxy silane (NAA-NH2). Subsequently, the trypsin enzyme was immobilized on the NAA pore walls. The sensing principle of proposed IRS sensor to cytochrome c is based on a change in the intensity of the reflected light to a charge-coupled device (CCD) detector after digesting of cytochrome c by immobilized trypsin enzymes on NAA-NH2 into the heme-peptide fragment. The heme-peptide fragment then oxidized 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) to green color ABTS·- anion radical in the presence of hydrogen peroxide. The generated green color ABTS·- anion radical solution adsorbed the white light and therefore the intensity of the reflected light from NAA to the CCD decreased. The decrease in the intensity of the white light had a logarithmic relationship with the concentration of the cytochrome c in the range of 1-100 nM. The limit of detections (LOD) for cytochrome c was 0.5 nM. The proposed biosensor exhibited high selectivity, sensitivity, and good stability.


Assuntos
Técnicas Biossensoriais , Citocromos c/isolamento & purificação , Neoplasias/sangue , Tripsina/química , Óxido de Alumínio/química , Benzotiazóis/química , Citocromos c/sangue , Humanos , Peróxido de Hidrogênio/química , Interferometria , Nanoporos , Neoplasias/diagnóstico , Análise Espectral , Ácidos Sulfônicos/química
15.
Chemosphere ; 245: 125560, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31864065

RESUMO

Bauxite residue is the by-product of the aluminium industry with an annual output of more than 200 million metric tons in China. Its treatment is still a big problem because more than 96% of that is stockpiled on land causing environmental pollution and threatening the human health. This study used bauxite residue to remove Cr (Ⅲ) from aqueous solution and analyzed the removal mechanism. The removal time was dependent on the initial concentrations of Cr (Ⅲ) and different active components acted on different reaction period. Reaction time increased from <5 min to >2 h with an increase of Cr (Ⅲ) concentration from 5 to 100 and 170 mg/L. The existing forms of adsorbed-Cr were iron oxide-bound Cr (40.80%-87.85%), sulfide-bound Cr (4.04%-20.28%) and residue (6.60%-33.72%). All the components started to react as soon as bauxite residue was added. Cr did not precipitate in the presence of high alkalinity bauxite residue due to the slow release of alkalinity maintaining pH < 6, thus producing Cr(OH)2+, Cr2(OH)24+ and Cr3(OH)45+ by hydrolysis without precipitation. Fe2O3 and Al-containing components were the main active phases for Cr (Ⅲ) removal, with the reaction time lasting more than 2 h and producing Ca6Al4Cr2O15, AlCr2, (Si, Al)2O4, Fe(Cr, Al)2O4, FeCr2Si3O12, MgCr0·1Fe1·9O4 and MgCr0·4Fe1·6O4. Finally, bauxite residue was granulated and used for column tests. Cr (Ⅲ) wastewater (1 and 50 mg/L) was treated and the effluent can meet the first level of the Shanghai standard (0.1 mg/L) defined by Integrated Wastewater Discharge Standard (DB 31/199-2009).


Assuntos
Óxido de Alumínio/química , Cromo/química , Poluentes Químicos da Água/química , Adsorção , Alumínio/química , China , Poluição Ambiental , Compostos Férricos , Modelos Químicos , Purificação da Água/métodos
16.
Molecules ; 25(1)2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31878339

RESUMO

In situ formation of intermetallic/ceramic composites composed of molybdenum silicides (Mo5Si3 and Mo3Si) and magnesium aluminate spinel (MgAl2O4) was conducted by combustion synthesis with reducing stages in the mode of self-propagating high-temperature synthesis (SHS). The SHS process combined intermetallic combustion between Mo and Si with metallothermic reduction of MoO3 by Al in the presence of MgO. Experimental evidence showed that combustion velocity and temperature decreased with increasing molar content of Mo5Si3 and Mo3Si, and therefore, the flammability limit determined for the reaction at Mo5Si3 or Mo3Si/MgAl2O4 = 2.0. Based upon combustion wave kinetics, the activation energies, Ea = 68.8 and 63.8 kJ/mol, were deduced for the solid-state SHS reactions producing Mo5Si3- and Mo3Si-MgAl2O4 composites, respectively. Phase conversion was almost complete after combustion, with the exception of trivial unreacted Mo existing in both composites and a minor amount of Mo3Si in the Mo5Si3-MgAl2O4 composite. Both composites display a dense morphology formed by connecting MgAl2O4 crystals, within which micro-sized molybdenum silicide grains were embedded. For equimolar Mo5Si3- and Mo3Si-MgAl2O4 composites, the hardness and fracture toughness are 14.6 GPa and 6.28 MPa m1/2, and 13.9 GPa and 5.98 MPa m1/2, respectively.


Assuntos
Óxido de Alumínio/síntese química , Temperatura Alta , Óxido de Magnésio/síntese química , Molibdênio/química , Compostos de Silício/química , Óxido de Alumínio/química , Processamento de Imagem Assistida por Computador , Cinética , Óxido de Magnésio/química , Espectrometria por Raios X , Difração de Raios X
17.
Nanoscale ; 11(46): 22369-22377, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31729502

RESUMO

Atomic layer deposited (ALD) ultra-thin alumina film is proposed to control the operational lifetimes of fully biodegradable (FB-) surface sensitive surface acoustic wave (SAW) devices. SAW devices encapsulated with conventional thick organic materials fail to function effectively, while devices with an ultra-thin alumina encapsulation layer (AEL) function normally with high performance. After being subjected to degradation in water, a FB-SAW device with no AEL starts to degrade immediately and fails within 8 h, due to dissolution of the tungsten electrode and piezoelectric material (ZnO). The coating of an ultra-thin AEL on the surfaces prevents SAW devices from undergoing degradation in water and enables SAW devices to perform normally before the AEL is dissolved. The stable operation lifetimes of SAW devices are linearly dependent on the AEL thickness, thus allowing for the design of devices with precisely controlled operational lifetimes and degradation times. The results show that all the materials used could be degraded; also, in vitro cytotoxicity tests indicate that the encapsulated FB-SAW devices are biocompatible, and cells can adhere and proliferate on them normally, demonstrating great potential for broader biodegradable electronic device applications.


Assuntos
Óxido de Alumínio/química , Eletrônica , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Humanos , Hidrólise , Óxidos/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Tungstênio/química , Óxido de Zinco/química
18.
Environ Sci Pollut Res Int ; 26(34): 35121-35130, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31679140

RESUMO

The study was initiated to evaluate constructed wetland technology as a method for treating alkaline (pH 8.0-8.6) drainage high in Al, Mo, V, As and Ga originating from bauxite residue storage areas. Pilot-scale horizontal flow constructed wetlands were operated over a 40-week period using three filter materials (granitic gravel, bauxite and alum water treatment sludge), and half of the wetlands were planted with Phragmites australis and the other half left unplanted. Gravel was the least effective medium for removing the target elements, while of the two active media, water treatment sludge was more effective than bauxite. Plants removed only small amounts of elements into their above- and below-ground dry matter (0.4-4.9% of that added). Nonetheless, the presence of plants greatly increased the effectiveness of all three media since their presence decreased effluent pH values by 0.5-1.3 pH units and that of the filter media by 0.4 pH units. Removal of elements followed the order Al > Ga > V > As > Mo. For planted wetlands, total elemental removal ranged from 18 to 98% for gravel, 80 to 99% for bauxite, and 93 to 99% for water treatment sludge. The lowest removal was for Mo (ranging from 18% for gravel to 93% for water treatment sludge) and the highest for Al (ranging from 98% in gravel to 99% in water treatment sludge). A sequential fractionation scheme for As, V and Mo on filter material at the end of the experiment showed that for bauxite and water treatment sludge, V and As were concentrated in the NaOH extractable fraction while Mo was concentrated in the less strongly adsorbed NaHCO3 extractable fraction. It was concluded that a constructed wetland with water treatment sludge as an active filter material is an effective technology for removal of the target elements from the alkali drainage.


Assuntos
Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Áreas Alagadas , Adsorção , Compostos de Alúmen , Óxido de Alumínio/química , Poaceae , Esgotos/química , Águas Residuárias/química , Purificação da Água/métodos
19.
Molecules ; 24(22)2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31739418

RESUMO

Two routes of preparation of mesoporous Ni-alumina materials favoring the intermediate formation of nanostructured nickel-aluminate are presented. The first one involves an aluminum containing MOF precursor used as sacrificial template to deposit nickel while the second is based on a one-pot synthesis combined to an EISA method. As shown by a set of complementary techniques, the nickel-aluminate nanospecies formed after calcination are homogeneously distributed within the developed mesoporous alumina matrices whose porous characteristics vary depending on the preparation method. A special attention is paid to electron-microscopy observations using especially STEM imaging with high chemical sensitivity and EDS elemental mapping modes that help visualizing the extremely high nickel dispersion and highlight the strong metal anchoring to the support that persists after reduction. This leads to active nickel nanoparticles particularly stable in the reaction of dry reforming of methane.


Assuntos
Óxido de Alumínio/química , Dióxido de Carbono/química , Nanopartículas Metálicas/química , Metano/química , Catálise , Nanoestruturas/química , Porosidade , Propriedades de Superfície
20.
PLoS One ; 14(10): e0224208, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31634370

RESUMO

Multi-metallic alloy nanoparticles (MNPs) can offer valuable opportunities to meet the various demands of applications. MNPs consist of various noble metallic elements can combine diverse electronic, optical and catalytic properties in a single NP configuration, thus taking the advantage of each element. In this paper, the fabrication of tri- and quad- metallic alloy NPs with noble elements (Ag, Au, Pd and Pt) and the corresponding localized surface plasmon resonance (LPSR) properties are systematically demonstrated. Tri- and quad-metallic alloy NPs come in various size and configurations by the solid-state dewetting of Ag/Au/Pd/Pt quad-layers on sapphire (0001). Tri-metallic AuPdPt NPs are demonstrated by the systematic control of growth temperature along with the significant Ag atom sublimation. Strongly enhanced and tunable LPSR is exerted in the UV-VIS regions depending upon the size, configuration, spacing and elemental composition of the MNPs. The size dependent LSPR response of MNPs is discussed based on the absorption and scattering along with the excitation of dipolar, quadrupolar, high order and multipolar resonance modes. The MNPs exhibit much stronger and dynamic LSPR bands as compared with the monometallic Pt and Pd NPs with the comparable size and configurations.


Assuntos
Óxido de Alumínio/química , Ouro/química , Nanopartículas Metálicas/química , Paládio/química , Platina/química , Prata/química , Catálise , Propriedades de Superfície
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