Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 40
Filtrar
1.
Molecules ; 29(9)2024 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-38731513

RESUMO

The various wastes generated by silkworm silk textiles that are no longer in use are increasing, which is causing considerable waste and contamination. This issue has attracted widespread attention in countries that use a lot of silk. Therefore, enhancing the mechanical properties of regenerated silk fibroin (RSF) and enriching the function of silk are important directions to expand the comprehensive utilization of silk products. In this paper, the preparation of RSF/Al2O3 nanoparticles (NPs) hybrid fiber with different Al2O3 NPs contents by wet spinning and its novel performance are reported. It was found that the RSF/Al2O3 NPs hybrid fiber was a multifunctional fiber material with thermal insulation and UV resistance. Natural light tests showed that the temperature rise rate of RSF/Al2O3 NPs hybrid fibers was slower than that of RSF fibers, and the average temperature rose from 29.1 °C to about 35.4 °C in 15 min, while RSF fibers could rise to about 40.1 °C. UV absorption tests showed that the hybrid fiber was resistant to UV radiation. Furthermore, the addition of Al2O3 NPs may improve the mechanical properties of the hybrid fibers. This was because the blending of Al2O3 NPs promoted the self-assembly of ß-sheets in the RSF reaction mixture in a dose-dependent manner, which was manifested as the RSF/Al2O3 NPs hybrid fibers had more ß-sheets, crystallinity, and a smaller crystal size. In addition, RSF/Al2O3 NPs hybrid fibers had good biocompatibility and durability in micro-alkaline sweat environments. The above performance makes the RSF/Al2O3 NPs hybrid fibers promising candidates for application in heat-insulating and UV-resistant fabrics as well as military clothing.


Assuntos
Óxido de Alumínio , Fibroínas , Nanopartículas , Raios Ultravioleta , Fibroínas/química , Nanopartículas/química , Óxido de Alumínio/química , Animais , Bombyx , Temperatura Alta , Humanos , Seda/química
2.
Molecules ; 29(6)2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38542842

RESUMO

This study concentrates on assessing the insecticidal attributes of the γ-Al2O3 nanoparticles derived from the remnants of Mentha pulegium, which include essential oil, ethanolic extract, and plant waste. The synthesis of the γ-Al2O3 nanoparticles was executed using a direct sol-gel procedure, affirming the crystal structure according to extensive physicochemical analyses such as UV-Vis, XRD, FTIR, and SEM. Evaluation of the insecticidal activity in vitro was conducted against Xylosandrus crassiusculus, a pest that infests carob wood, utilizing strains from diverse forests in the Khenifra region, situated in the Moroccan Middle Atlas. The lethal doses 50 ranged from 40 mg/g to 68 mg/g, indicating moderate effectiveness compared to the commercial insecticide Permethrin. Optimization of the conditions for the efficiency of the γ-Al2O3 nanoparticles was determined using experimental plans, revealing that time, humidity, and temperature were influential factors in the lethal dose 50 of these nanomaterials. Moreover, this study encompasses the establishment of correlations using Principal Component Analysis (PCA) and Ascending Hierarchical Classification (AHC) among various geographic, biological, and physical data, amalgamating geographic altitude and γ-Al2O3 nanoparticle insecticide parameters, as well as the attributes of the mechanical tests conducted on the carob wood affected by insects. The correlations highlight the close connections between the effectiveness of the insecticide, mountain altitude, and the mechanical parameters that were examined. Ultimately, these nanoparticles demonstrate promising potential as alternative insecticides, thus opening up encouraging prospects for safeguarding against carob wood pests.


Assuntos
Besouros , Galactanos , Inseticidas , Mananas , Mentha pulegium , Nanopartículas , Gomas Vegetais , Gorgulhos , Animais , Inseticidas/farmacologia , Inseticidas/química , Mentha pulegium/química
3.
Molecules ; 27(24)2022 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-36558120

RESUMO

The traditional method of obtaining fresh water for drinking is by burning fossil fuels, emitting greenhouse gases into the atmosphere. However, renewable energy is gaining more traction since it is available free of cost for producing fresh water. In this study, Al2O3 nanoparticles were distributed in a phase change material (paraffin wax) that had been fixed at a hemispherical distiller water basin. Three scenarios with three hemispherical distillers were examined. A conventional hemispherical distiller (CHD), a conventional hemispherical distiller with paraffin wax as a phase change material (CHD-PCM), and a conventional hemispherical distiller with PCM partially filled with Al2O3 nanoparticles (CHD-N-PCM) were tested under the same climatic conditions. The experimental results showed that CHD gave a daily yield of 4.85 L/m2/day, while CHD-PCM increased the yield to up to 6.2 L/m2/day with a 27.84% daily yield enhancement. The addition of Al2O3 nanoparticles to paraffin wax CHD-N-PCM improved hemispherical distillate yield up to 8.3 L/m2/day with a 71.13% increase over CHD yield.


Assuntos
Nanopartículas , Parafina , Atmosfera , Combustíveis Fósseis , Água Doce
4.
J Appl Toxicol ; 41(8): 1316-1329, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33269475

RESUMO

Little is known about the uptake, biodistribution, and biological responses of nanoparticles (NPs) and their toxicity in developing animals. Here, male and female juvenile Sprague-Dawley rats received four consecutive daily doses of 10 mg/kg Al2 O3 NP (diameter: 24 nm [transmission electron microscope], hydrodynamic diameter: 148 nm) or vehicle control (water) by gavage between postnatal days (PNDs) 17-20. Basic neurobehavioral and cardiac assessments were performed on PND 20. Animals were sacrificed on PND 21, and selected tissues were collected, weighed, and processed for histopathology or neurotransmitter analysis. The biodistribution of Al2 O3 NP in tissue sections of the intestine, liver, spleen, kidney, and lymph nodes were evaluated using enhanced dark-field microscopy (EDM) and hyperspectral imaging (HSI). Liver-to-body weight ratio was significantly increased for male pups administered Al2 O3 NP compared with control. HSI suggested that Al2 O3 NP was more abundant in the duodenum and ileum tissue of the female pups compared with the male pups, whereas the abundance of NP was similar for males and females in the other tissues. The abundance of NP was higher in the liver compared with spleen, lymph nodes, and kidney. Homovanillic acid and norepinephrine concentrations in brain were significantly decreased following Al2 O3 NP administration in female and male pups, whereas 5-hydroxyindoleacetic acid was significantly increased in male pups. EDM/HSI indicates intestinal uptake of Al2 O3 NP following oral administration. Al2 O3 NP altered neurotransmitter/metabolite concentrations in juvenile rats' brain tissues. Together, these data suggest that orally administered Al2 O3 NP interferes with the brain biochemistry in both female and male pups.


Assuntos
Óxido de Alumínio/toxicidade , Coração/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Neurotransmissores/metabolismo , Administração Oral , Óxido de Alumínio/administração & dosagem , Animais , Encéfalo/metabolismo , Eletrocardiografia/efeitos dos fármacos , Feminino , Masculino , Nanopartículas Metálicas/administração & dosagem , Atividade Motora/efeitos dos fármacos , Neurotransmissores/análise , Ratos , Ratos Sprague-Dawley , Teste de Desempenho do Rota-Rod , Distribuição Tecidual
5.
Molecules ; 25(9)2020 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-32380658

RESUMO

The flow of nanofluid over a curved Riga surface is a topic of interest in the field of fluid dynamics. A literature survey revealed that the impacts of freezing temperature and the diameter of nanoparticles on the heat transfer over a curved Riga surface have not been examined so far. Therefore, the flow of nanoparticles, which comprises the influences of freezing temperature and nanoparticle diameter in the energy equation, was modeled over a curved Riga surface. The model was reduced successfully in the nondimensional version by implementing the feasible similarity transformations and effective models of nanofluids. The coupled nonlinear model was then examined numerically and highlighted the impacts of various flow quantities in the flow regimes and heat transfer, with graphical aid. It was examined that nanofluid velocity dropped by increasing the flow parameters γ and S, and an abrupt decrement occurred at the surface of the Riga sheet. The boundary layer region enhances for larger γ. The temperature distribution was enhanced for a more magnetized nanofluid, and the thermal boundary layer increased with a larger R parameter. The volume fraction of the nanoparticles favors the effective density and dynamic viscosity of the nanofluids. A maximum amount of heat transfer at the surface was observed for a more magnetized nanofluid.


Assuntos
Óxido de Alumínio/química , Nanopartículas/química , Temperatura Baixa , Simulação por Computador , Congelamento , Temperatura Alta , Hidrodinâmica , Dinâmica não Linear , Condutividade Térmica , Viscosidade
6.
Molecules ; 25(8)2020 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-32294974

RESUMO

The flow of nanofluid between infinite parallel plates suspended by micro-cantilever sensors is significant. The analysis of such flows is a rich research area due to the variety of applications it has in chemical, biological and medical sciences. Micro-cantilever sensors play a significant role in accurately sensing different diseases, and they can be used to detect many hazardous and bio-warfare agents. Therefore, flow water and ethylene glycol (EG) composed by γ-nanoparticles is used. Firstly, the governing nanofluid model is transformed into two self-similar nanofluid models on the basis of their effective models. Then, a numerical method is adopted for solution purposes, and both the nanofluid models are solved. To enhance the heat transfer characteristics of the models, the effective Prandtl model is ingrained in the energy equation. The velocity F'(η) decreases with respect to the suction of the fluid, because more fluid particles drags on the surface for suction, leading to an abrupt decrement in F'(η). The velocity F'(η) increases for injection of the fluid from the upper end, and therefore the momentum boundary layer region is prolonged. A high volume fraction factor is responsible for the denser characteristics of the nanofluids, due to which the fluids become more viscous, and the velocity F'(η) drops abruptly, with the magnetic parameters favoring velocity F'(η). An increase in temperature ß ( η ) of Al2O3-H2O and γAl2O3-C2H6O2 nanofluids was reported at higher fraction factors with permeable parameter effects. Finally, a comparative analysis is presented by restricting the flow parameters, which shows the reliability of the study.


Assuntos
Nanopartículas/química , Nanotecnologia/instrumentação , Nanotecnologia/métodos , Óxido de Alumínio/química , Simulação por Computador , Etilenoglicol/química , Temperatura Alta , Hidrodinâmica , Magnetismo , Modelos Teóricos , Reprodutibilidade dos Testes , Temperatura , Viscosidade , Água/química
7.
Toxicol Mech Methods ; 30(7): 546-554, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32580614

RESUMO

Manufactured nanoparticles (NPs) can potentially cause negative effects on molecular (proteins and nucleic acids), subcellular, cellular, tissue, organ, and organism due to their unusual physicochemical characteristics. Ionizable NPs in water (e.g., Al2O3-NPs) may create toxic effects on aquatic animals. The present research determined the influences of Al2O3-NPs and appropriate concentrations of ionizing Al(III) using water-soluble AlCl3 in zebrafish larvae (72 h post-fertilization, Danio rerio) by analyzing transcriptional alterations of stress-associated genes (rad51, p53, mt2) with quantitative real-time PCR (qRT-PCR). In addition, genotoxic effects of Al(III) and Al2O3-NPs were evaluated. The lethal concentrations that cause death of 50% (LC50) of zebrafish larvae when exposed to 0-50 mg/l Al(III) and 0-500 mg/l Al2O3-NPs were 3.26 ± 0.38 and 130.19 ± 5.59 mg/l, respectively, for 96 h. A concentration-dependent increase was observed in the genotoxicity in cells of larvae exposed to Al(III) and Al2O3-NPs for 96 h. DNA damage was more severe in larvae exposed to Al(III) (41.0% tail) than that of Al2O3-NPs (21.8% tail). A complex induction of stress-associated genes was observed in fish and this induction was not directly related to the concentrations of Al(III) and Al2O3-NPs, although a significant induction was detected in mt2 gene of larvae exposed to Al(III) and Al2O3-NPs relative to control group. The induction levels of mt2 were 4.13 ± 0.1 and 2.13 ± 0.1-fold change (mean ± S.E.M.) in larvae at 15 mg/l of Al(III) and 100 mg/l of Al2O3-NP concentrations, respectively.


Assuntos
Cloreto de Alumínio/toxicidade , Óxido de Alumínio/toxicidade , Dano ao DNA , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Transcriptoma/efeitos dos fármacos , Proteínas de Peixe-Zebra/genética , Peixe-Zebra/genética , Animais , Relação Dose-Resposta a Droga , Solubilidade , Peixe-Zebra/embriologia , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/metabolismo
8.
Ecotoxicol Environ Saf ; 165: 423-433, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30218965

RESUMO

Wide use of Al2O3 nanoparticles (NPs) leading to their possible escape into environment and their interaction with living organisms demands immediate attention. We evaluated impact of nanoparticulate (Al2O3-NPs) and ionic (Al3+) forms of aluminium on early seedling growth of Vigna radiata. While Al3+ inhibited growth of seedlings, Al2O3-NPs did not affect it negatively. Unlike enhancement in proline, malondialdehyde and H2O2 levels in roots and shoots induced by Al3+, these stress markers remained unaltered by Al2O3-NPs. No signs of membrane damage were recorded in roots of seedlings raised in presence of Al2O3-NPs; this was witnessed from insignificant electrolyte leakage and Evans blue uptake. Activities of antioxidant enzymes, i.e., superoxide dismustase, catalase, guaiacol peroxidase in root and shoot were enhanced by Al3+. However, they were unaffected by Al2O3-NPs. Al3+ enhanced levels of non-protein thiols, phenolics and ascorbate, with no alterations induced by Al2O3-NPs. These findings revealed that, Al2O3-NPs did not induce oxidative stress in seedlings. Seedlings raised in Al3+ showed higher uptake of Al than those grown in Al2O3-NPs; Al content was higher in roots. Al was not detected in shoots of seedlings grown in Al2O3-NPs. Lower translocation of Al in seedlings raised in Al2O3-NPs was due to adsorption/restriction of Al2O3-NPs on root surface. Al3+ caused ruptures on root epidermis of seedlings and inhibited root-hair formation, whereas no structural damage was caused by Al2O3-NPs. Our findings revealed that while ionic Al is highly toxic, nanoparticulate form of Al is non-toxic to growth of V. radiata.


Assuntos
Óxido de Alumínio/toxicidade , Alumínio/toxicidade , Poluentes Ambientais , Nanopartículas/toxicidade , Plântula/crescimento & desenvolvimento , Vigna/efeitos dos fármacos , Alumínio/metabolismo , Ácido Ascórbico/metabolismo , Catalase/metabolismo , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Peroxidase/metabolismo , Fenóis/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Brotos de Planta/metabolismo , Prolina/metabolismo , Plântula/efeitos dos fármacos , Compostos de Sulfidrila/metabolismo , Superóxido Dismutase/metabolismo , Vigna/crescimento & desenvolvimento , Vigna/metabolismo
9.
Entropy (Basel) ; 20(4)2018 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-33265333

RESUMO

During the last decade, second law analysis via entropy generation has become important in terms of entropy generation minimization (EGM), thermal engineering system design, irreversibility, and energy saving. In this study, heat transfer and entropy generation characteristics of flows of multi-walled carbon nanotube-based nanofluids were investigated in horizontal minitubes with outer and inner diameters of ~1067 and ~889 µm, respectively. Carbon nanotubes (CNTs) with outer diameter of 10-20 nm and length of 1-2 µm were used for nanofluid preparation, and water was considered as the base fluid. The entropy generation based on the experimental data, a significant parameter in thermal design system, was examined for CNTs/water nanofluids. The change in the entropy generation was only seen at low mass fractions (0.25 wt.% and 0.5 wt.%). Moreover, to have more insight on the entropy generation of nanofluids based on the experimental data, a further analysis was performed on Al2O3 and TiO2 nanoparticles/water nanofluids from the experimental database of the previous study of the authors. The corresponding results disclosed a remarkable increase in the entropy generation rate when Al2O3 and TiO2 nanoparticles were added to the base fluid.

10.
Biotechnol Appl Biochem ; 63(3): 320-7, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-25779086

RESUMO

Aluminum oxide nanoparticles (Al2 O3 -NPs) are important ceramic materials that have been used in a variety of commercial and industrial applications. However, the impact of acute and chronic exposure to Al2 O3 -NPs on the environment and on human health has not been well studied. In this investigation, we evaluated the cytotoxic effects of Al2 O3 -NPs on human mesenchymal stem cells (hMSCs) by using a cell viability assay and observing cellular morphological changes, analyzing cell cycle progression, and monitoring the expression of cell cycle response genes (PCNA, EGR1, E2F1, CCND1, CCNC, CCNG1, and CYCD3). The Al2 O3 -NPs reduced hMSC viability in a dose- and time-dependent manner. Nuclear condensation and fragmentation, chromosomal DNA fragmentation, and cytoplasmic vacuolization were observed in Al2 O3 -NP-exposed cells. The nuclear morphological changes indicated that Al2 O3 -NPs alter cell cycle progression and gene expression. The cell cycle distribution revealed that Al2 O3 -NPs cause cell cycle arrest in the sub-G0-G1 phase, and this is associated with a reduction in the cell population in the G2/M and G0/G1 phases. Moreover, Al2 O3 -NPs induced the upregulation of cell cycle response genes, including EGR1, E2F1, and CCND1. Our results suggested that exposure to Al2 O3 -NPs could cause acute cytotoxic effects in hMSCs through cell cycle regulatory genes.


Assuntos
Óxido de Alumínio/toxicidade , Ciclo Celular/efeitos dos fármacos , Ciclina D1/genética , Proteína 1 de Resposta de Crescimento Precoce/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos dos fármacos , Nanopartículas/química , Óxido de Alumínio/química , Transporte Biológico/efeitos dos fármacos , Biomarcadores/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo
11.
Sci Rep ; 14(1): 16957, 2024 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-39043797

RESUMO

The presence of methylene blue (MB) dye in wastewater has raised concern about human health and environmental ecology due to potential carcinogenic, and mutagenic effects. Therefore, this work aims to remove MB dye from wastewater using γ-Al2O3 nanoparticles synthesized from aluminum scrap via simple electrolytic method. The successful synthesis of the adsorbent was confirmed by a range of spectroscopy and microscopy techniques, including XRD, SEM, FTIR, and BET. The central composite design (CCD) of the response surface methodology (RSM) method was used to optimize the processing parameters such as solution pH, contact time, initial MB concentration, and adsorbent dose. The ANOVA results clearly shows that the quadratic model (p < 0.0001) was sufficient to the best predicting of the removal performance of MB dye (R2 = 0.9862). The optimum condition for the maximum MB dye removal (98.91%) was achieved at solution pH of 8.298, initial MB concentration of 31.657 mg/L, adsorbent dose of 0.387 g/L, and contact time of 46.728 min. Nano-γ-Al2O3 was shown to have a good surface area of 59 mg2/g by BET analysis. The adsorption kinetics follows the pseudo-second-order model (R2 = 0.997). With a maximum adsorption capacity of 137.17 mg/g, the Langmuir isotherm model (R2 = 984) provides the best fit to the adsorption isotherm data, indicating a monolayer adsorption process. Furthermore, thermodynamic analysis demonstrated that the adsorption of MB dye was an endothermic and spontaneous process. The reusability study showed that γ-Al2O3 nano-adsorbent retained 85.08% of its original removal efficiency after five cycles. According to the findings of the study, MB dye molecules were taken up by γ-Al2O3 nano-adsorbent via hydrogen bond formation, Van der Waals interaction, and electrostatic attraction. Therefore, γ-Al2O3 nanoparticles can be used as a potentially eco-friendly and low-cost adsorbent for the removal of MB dye from aqueous solutions.

12.
Environ Sci Pollut Res Int ; 30(49): 106838-106859, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36809619

RESUMO

Photovoltaic (PV) technology is considered one of the most effective and promising renewable sources of energy. The PV system's efficiency strongly depends on its operating temperature, which acts as a defect to the electrical efficiency by increasing over 25 °C. In this work, a comparison was performed between three traditional polycrystalline solar panels simultaneously at the same time and under the same weather conditions. The electrical and thermal performances of the photovoltaic thermal (PVT) system integrated with a serpentine coil configured sheet with a plate thermal absorber setup are evaluated using water and aluminum oxide nanofluid. For higher mass flow rates and nanoparticle concentrations, an improvement in the PV modules short-circuit current (Isc) and open-circuit voltage (Voc) yield and electrical conversion efficiency is achieved. The enhancement in the PVT electrical conversion efficiency is 15.5%. For 0.05% volume concentration of Al2O3 and flow rate of 0.07 kg/s, an enhancement of 22.83% of the temperature of PVT panels' surface over the reference panel has been obtained. An uncooled PVT system reached a maximum panel temperature of 75.5 °C at noontime and obtained an average electrical efficiency of 12.156%. Water and nanofluid cooling reduce the panel temperature by 10.0 °C and 20.0 °C at noontime, respectively.


Assuntos
Temperatura Baixa , Energia Solar , Temperatura , Transição de Fase , Tempo (Meteorologia) , Água
13.
Micron ; 168: 103443, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36905753

RESUMO

An Al-15 Al2O3 alloy was added into Al-12Si melt to investigate the nano-treating effect of Al2O3 nanoparticles on eutectic Si crystals. It was found that Al2O3 clusters may be partly swallowed by eutectic Si or distribute surrounding them. As a result, the flake-like eutectic Si in Al-12Si alloy can transform to granular or worm-like morphologies, attributing to the influence of Al2O3 nanoparticles on the growth behavior of eutectic Si crystals. The orientation relationship between Si and Al2O3 was identified, and the possible modifying mechanisms were discussed.

14.
Sci Bull (Beijing) ; 68(18): 2054-2062, 2023 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-37599177

RESUMO

Due to the huge energy consumption of traditional cooling- and heating-based electricity, passive radiative cooling and solar heating with a minimum carbon footprint using the outer space and Sun as natural thermodynamic resources have attracted much attention. However, most passive devices are static and monofunctional, and cannot meet the practical requirements of dynamic cooling and heating under various conditions. Here, we demonstrate a smart thermal-gated (STG) bilayer membrane that enables fully automatic and temperature-adaptive radiative cooling and solar heating. Specifically, this device can switch from reflective to absorptive (white to black) in the solar wavelength with the reduction in optical scattering upon ambient temperature, corresponding to a sunlight reflectivity change from 0.962 to 0.059 when the temperature drops below ∼30 °C, whereas its mid-infrared emissivity remains at ∼0.95. Consequently, this STG membrane achieves a temperature of ∼5 °C below ambient (a key signature of radiative cooling) under direct sunlight (peak solar irradiance >900 W m-2) in summer and a solar heating power of ∼550 W m-2 in winter. Theoretical analysis reveals the substantial advantage of this switchable cooling/heating device in potential energy saving compared with cooling-only and heating-only strategies when widely used in different climates. It is expected that this work will pave a new pathway for designing temperature-adaptive devices with zero energy consumption and provide an innovative way to achieve sustainable energy.

15.
Int J Mol Sci ; 13(9): 11941-11953, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23109893

RESUMO

Colloidal Cu@CuAlO(2)-Al(2)O(3) bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a (60)Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO(2)-Al(2)O(3) nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO(2)-Al(2)O(3) nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation.


Assuntos
Compostos de Alumínio/síntese química , Cobre/química , Raios gama , Nanopartículas/química , 2-Propanol/química , Compostos de Alumínio/química , Coloides/síntese química , Coloides/química , Povidona/química
16.
Materials (Basel) ; 15(13)2022 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-35806552

RESUMO

The output of the latent heat storage devices (LHSDs), based on some phase change materials (PCMs), depends upon the thermophysical properties of the phase change material used. In this study, a paraffin-based nanofluid, blended with aluminum oxide (Al2O3) nanoparticles, is used as PCM for performance evaluation. A three-dimensional (3D) numerical model of regenerative type shell-and-tube LHSD is prepared using COMSOL Multiphysics® 4.3a software to estimate the percentage of melt and the average temperature of the analyzed nanofluids. The results of this study are in close agreement with those reported in the literature, thereby ensuring the validation of the numerically predicted results. The effects of adding the nanoparticles on the rate of melting, as well as solidification and rate of stored/liberated energy, are studied. The results revealed that, by adding 10% nanoparticles of Al2O3, the melting rate of pure-paraffin-based LHSD improved by about 2.25 times. In addition, the rate of solidification was enhanced by 1.8 times. On the other hand, the heat of fusion and specific heat capacities were reduced, which, in turn, reduced the latent and sensible heat-storing capabilities. From the outcomes of the present research, it can be inferred that combining LHSD with a solar water heater may be used in technologies such as biogas generation.

17.
J Appl Biomater Funct Mater ; 20: 22808000221136483, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36540943

RESUMO

APPLICATIONS: The interaction of nanoparticles and base solvents of different nature attained much interest of the researchers in the recent time. These use in medication, detection of cancer cells, applied thermal engineering, and electrical and mechanical engineering. Among the broad range of applications, investigation of nanofluid through converging/diverging channel is important which is of much interest in the field of medical sciences. PURPOSE AND METHODOLOGY: The core purpose of this study is to introduce a new heat transfer model for two natures of nanofluids with bi host solvents. The model in hand achieved through nanofluid expressions, similarity equations and induction of novel dissipation effects. At later stage, numerical treatment is performed to explore the actual behaviour of nanofluids inside the oblique walls which is very important. CORE FINDINGS: From the drawn results, it is found that the motion could be controlled by expanding the channel walls (α=5o) and high Re and in Al2O3-H2O it is optimum. The nanofluids based on Al2O3 and C2H6O2 have much ability to transmit heat than the other nanofluids. Moreover, dissipation effects (Ec=0.1,0.2,0.3,0.4) played significant role and boosted the temperature while keeping Re=70,α=5o and α=-5o, respectively. Also, the study is validated and achieved good agreement between existing and the current study.


Assuntos
Nanopartículas , Nanoestruturas , Temperatura Alta , Solventes , Temperatura
18.
Environ Sci Pollut Res Int ; 29(19): 28115-28126, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34984620

RESUMO

The problem of potable water shortage all over the world made the scientists seek for solutions to overcome this problem. Solar distiller is one of the introduced solutions, but it demerited by the low freshwater output. In this proposed paper, a design modification includes the use of a convex dish absorber instead of the flat absorber liner. The modified solar distiller is nominated by dish solar distiller. The base of dish solar distiller was circular. In addition, a cotton wick was used as a wetting material for facilitating the evaporation process inside the distiller. Besides, the effect of different water heights in the clearance around the dish dome was investigated for 1, 3, 5, 7, 9, and 12 cm. Finally, the space under the dish absorber is filled with a phase change material of paraffin wax mixed with aluminum oxide nanoparticles. Experimental results revealed that the best dish height that provided the highest freshwater productivity was 9 cm, where the average daily yields of dish solar distiller (at 9 cm) and conventional distillers were reported as 4500 and 3000 mL/m2.day, respectively. Then, the productivity of dish solar distiller was improved by around 50% over that of the conventional distiller. In addition, when using the phase change material, the average daily distillate of dish solar distiller was improved by approximately 95% compared to that of the conventional solar still, where the distillate of conventional still and dish solar distiller with phase change material at 9 cm water depth was 3580 and 6980 mL/m2.day, respectively. Besides, the maximum thermal efficiency of dish solar distiller was obtained when using phase change material at 9 cm water depth, where it was 62.4% compared to 30% for the conventional distiller.


Assuntos
Água Potável , Nanopartículas , Purificação da Água , Água Doce , Luz Solar , Água
19.
J Colloid Interface Sci ; 606(Pt 1): 434-443, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34411826

RESUMO

HYPOTHESIS: Even a small fraction of nanoparticles in fluids affects the splashing behavior of a droplet upon impact on a smooth surface. EXPERIMENTS: Nanofluid drop impact onto a smooth sapphire substrate is experimentally investigated over wide ranges of Reynolds (102

20.
Food Chem ; 370: 131059, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34649018

RESUMO

A novel surface-enhanced Raman spectroscopy (SERS) method for the determination of nitrofurazone was developed using AuNPs/γ-Al2O3 nanoparticles protected by ß-cyclodextrin (ß-CD) as substrate prepared in our lab. The optimum experimental conditions were obtained from single factor procedure and response surface modeling. A linear relationship (ISERS = 508.96c + 31987.87, c: nmol L-1, R2 = 0.996) between SERS intensity and the concentration of nitrofurazone in the range of 3.3 - 667.0 nmol L-1 was established, the limit of detection (LOD) was found at nmol L-1 level (0.37 nmol L-1 by 3S0/S). The selectivity for the method was studied by the influences of foreign substances on the determination. The recoveries and RSD (n = 5) for the six meat samples were 95.1 % - 104.5% and 2.4 % - 4.8% respectively, which suggesting that the new SERS method was successfully to detecting nitrofurazone.


Assuntos
Nanopartículas Metálicas , beta-Ciclodextrinas , Ouro , Nitrofurazona , Análise Espectral Raman
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa