Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Mar Pollut Bull ; 203: 116425, 2024 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-38705004

RESUMO

To investigate the interplay between varying anthropogenic activities and sediment dynamics in an urban river (Turag, Bangladesh), this study involved 37-sediment samples from 11 different sections of the river. Neutron activation analysis and atomic absorption spectrometry were utilized to quantify the concentrations of 14 metal(oid)s (Al, Ti, Co, Fe, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn). This study revealed significant toxic metal trends, with Principal coordinate analysis explaining 62.91 % of the variance from upstream to downstream. The largest RSDs for Zn(287 %), Mn(120 %), and Cd(323 %) implies an irregular regional distribution throughout the river. The UNMIX-model and PMF-model were utilized to identify potential sources of metal(oid)s in sediments. ∼63.65-66.7 % of metal(oid)s in sediments originated from anthropogenic sources, while remaining attributed to natural sources in both models. Strikingly, all measured metal(oid)s' concentrations surpassed the threshold effect level, with Zn and Ni exceeding probable effect levels when compared to SQGs.

2.
Heliyon ; 10(3): e25579, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38356523

RESUMO

Pure and manganese-doped titanium dioxide nanoparticles (MnTiO2-NPs) were synthesized by the defect-oriented hydrothermal approach. The synthesized material was then characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), and UV-visible spectroscopy (UV-Vis). The agar well diffusion method assessed the antibacterial efficiency of TiO2 and MnTiO2-NPs against E. coli and S. aureus. Zone of inhibition (ZOI) formed by pure TiO2 was observed as 12 mm and 11.5 mm against E. coli and S. aureus, while for MnTiO2-NPs it was observed as 19 mm (E. coli) and 21 mm (S. aureus). The concentration of synthesized nanoparticles (10 mg/ml, and 20 mg/ml) was used for antibacterial studies. The efficacy of the pure and MnTiO2-NPs as an active photocatalyst for the degradation of methylene blue (MB) dye was also assessed using a UV light. It was observed that the photodegradation efficiency of 1 g of MnTiO2-NPs was higher than the same amount of pure TiO2. The results suggest that the photocatalyst concentration directly impacts the photodegradation of MB dye. The pH value was found to influence the photodegradation of MB dye at higher pH values. Based on the obtained results, MnTiO2-NPs were observed as a promising agent for microbial resistance and water remediation.

3.
Environ Sci Pollut Res Int ; 31(5): 8254-8273, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38175520

RESUMO

Naturally occurring radioactive materials (NORMs: 232Th, 226Ra, 40K) can reach our respiratory system by breathing of road dust which can cause severe health risks. Targeting the pioneering consideration of health risks from the NORMs in road dust, this work reveals the radioactivity abundances of NORMs in road dust from a megacity (Dhaka) of a developing country (Bangladesh). Bulk chemical compositions of U, Th, and K obtained from neutron activation analysis were converted to the equivalent radioactivities. Radioactivity concentrations of 226Ra, 232Th, and 40K in road dust ranged from 60-106, 110-159, and 488-709 Bq kg-1 with an average of 84.4 ± 13.1, 126 ± 11, and 549 ± 48 Bq kg-1, respectively. Estimated 226Ra, 232Th, and 40K radioactivities were, respectively, 1.7-3.0-, 3.7-5.3-, and 1.2-1.8-folds greater than the affiliated world average values. Mechanistic pathway of NORMs' enrichment and fractionation relative to the major origin (pedosphere) were evaluated concerning the water logging, relative solubility-controlled leaching and translocation, climatic conditions, and aerodynamic fractionations (dry and wet atmospheric depositions). Computation of customary radiological risk indices invokes health risks. Noticing the ingress of NOMR-holding dust into the human respiratory system along with the associated ionizing radiations, the computed radiological indices represent only the least probable health hazards. Nevertheless, in real situations, α-particles from the radioactive decay products of 232Th and 238U can create acute radiation damages of respiratory system. Policymakers should emphasize on limiting the dust particle evolution, and public awareness is required to alleviate the health risks.


Assuntos
Monitoramento de Radiação , Radioatividade , Poluentes Radioativos do Solo , Humanos , Poeira/análise , Bangladesh , Poluentes Radioativos do Solo/análise , Tório/análise
4.
Mar Pollut Bull ; 196: 115588, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37806014

RESUMO

This study was carried out on a negligible anthropogenically impacted Indo-Bangla transboundary river basin (Atrai, Bangladesh) to elicit radionuclides' and elemental distributions. Thirty sediment samples were collected from the Bangladesh portion of the river, and instrumental neutron activation analysis and HPGe γ-Spectrometry techniques were used to determine environmental radionuclides (e.g., 232Th, 226Ra, 40K) and associated elemental concentrations, respectively. Metal concentrations (Sc, V, Fe, Eu, Sm, La, Yb, Ce, Lu, Ta, Hf) were determined to comprehend the genesis of greater radioactivity. Recognizing the mean concentration of absorbed gamma dose rate (158.7 hGyh-1) is 2.88-times more than the recommended value (55 hGyh-1) that describes ionizing radiation concerns regarding potential health risks to the surrounding communities and the houses of native residents, which are constructed by Atrai river sediment. This work will assist relevant policymakers in exploring valuable heavy minerals and provide information regarding radiological health risks from a fluvial system.


Assuntos
Exposição à Radiação , Radioatividade , Metais/análise , Rios/química , Radioisótopos/análise , Exposição à Radiação/análise , Monitoramento Ambiental
5.
Environ Pollut ; 338: 122673, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37793543

RESUMO

Tannery-effluent is one of the top-ranked hazardous waste which is generally discharged into the river. To study the fluvial response toward the tannery-effluents and to trace anthropogenic foot-prints in the fluvial-system, a suite of systematically collected sediment and water samples were analyzed for radioactive (226Ra, 232Th, and 40K) and non-radioactive elements (Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg, and Pb). Neutron activation analysis and atomic absorption spectroscopy were used for elemental analysis, whereas HPGe-gamma-detector was used for measuring the primordial-radionuclides. Ranges of Cr-abundances in sediment and water were 63-4373 µg.g-1 and 15.6-52.2 µg.L-1, respectively which were ∼4-14 times higher than the geological background. Radioactivity concentrations of 226Ra, 232Th, and 40K ranged from 17.7-48.5, 36.1-81.6, and 687-1041 Bq.kg-1, respectively which were significantly depleted in effluent discharge point. Hence, primordial-radionuclides were used as natural tracers for tracing anthropogenic foot-prints which were explained in terms of dilution effect, redox environment and differential geo-environmental events/characteristics. From statistical-approaches and geochemical reasoning, elemental sources and responses in fluvial system were explored. Surprisingly, ecological & radiological risks were reduced while sediment quality guideline-based ecotoxicity & water-mediated health risks were increased by the incorporation of tannery effluents. This study describes the sedimentary response toward the received tannery effluents which is particularly explored by the primordial radionuclides.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Monitoramento Ambiental/métodos , Rios/química , Poluentes Químicos da Água/análise , Água/análise , Radioisótopos/análise , Metais Pesados/análise , Sedimentos Geológicos/química
6.
Chemosphere ; 339: 139733, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37544528

RESUMO

This study utilized surface sediments from a potentially less polluted transboundary Himalayan River (Brahmaputra: China-India-Bangladesh) to investigate the abundance of 15 geochemically and ecologically significant elements and to predict their sources and ecological consequences. INAA was applied to determine the elemental concentrations. The average abundances (µg.g-1) of Rb (94.20), Cs (4.49), Th (20.31), & U (2.73) were 1.12-2.26 folds elevated than shale. Environmental indices disclosed a pollution status ranging from "uncontaminated to moderately contaminated," with minimal Rb, U, and Th enrichment in the downstream zone. Consensus-based sediment quality guideline (SQG) threshold values suggested that only Cr (60% samples > TEL) may impose rare biological effects. Ecological risk indices suggested "minor to no" possible eco-toxicological risks for the accounted elements (Cr, Co, Mn, Zn, Sb, & As). The positive matrix factorization (PMF) model predicated the predominance of geogenic or crustal contributions (∼72.69%) for Al, K, Na, Ti, Co, Zn, Ba, Cs, As, Rb, Th, & U derived from elemental fractionations, mineral weathering, and bio-geo-chemical mobilization. The relative contributions of anthropogenic sources (∼27.31%; such as the construction of roads, settlement expansion, litter disposal, municipal waste discharge, mining activities, agricultural encroachment, etc.) on elemental distribution were significantly lower. The abundance of Cr and Mn was mainly influenced by anthropogenic sources. This study demonstrated the effectiveness of utilizing geo-environmental guidelines and receptor models in discriminating the natural & anthropogenic origins of metals in the complex riverine sediments of a less anthropogenically affected river.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Metais Pesados/análise , Monitoramento Ambiental , Sedimentos Geológicos , Poluição Ambiental/análise , Medição de Risco , China , Poluentes Químicos da Água/análise
7.
Saudi Pharm J ; 31(9): 101735, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37638224

RESUMO

Zinc ferrite nanoparticles (ZnFe2O4 NPs) have attracted extensive attention for their diverse applications including sensing, waste-water treatment, and biomedicine. The novelty of the present work is the fabrication of ZnFe2O4/RGO NCs by using a one-step hydrothermal process to assess the influence of RGO doping on the physicochemical properties and anticancer efficacy of ZnFe2O4 NPs. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy-dispersive X-ray(EDX), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), UV-vis spectroscopy, and Photoluminescence (PL) spectroscopy were employed to characterize prepared pure ZnFe2O4 NPs and ZnFe2O4/ RGO NCs. XRD results showed that the synthesized samples have high crystallinity. Furthermore, the average crystal sizes of ZnFe2O4 nanoparticles (NPs) and ZnFe2O4/RGO nanocomposites (NCs) were 51.08 nm and 54.36 nm, respectively. SEM images revealed that pure ZnFe2O4 NPs were spherical in shape with uniformly loaded on the surface of the RGO nanosheet. XPS and EDX analysis confirmed the elemental compositions of ZnFe2O4/RGO NCs. Elemental mapping of SEM shows that the elemental compositions (Zn, Fe, O, and C) were homogeneously distributed in ZnFe2O4/RGO NCs. The intensity of FT-IR spectra depicted that pure ZnFe2O4 NPs were successfully anchored into the RGO nanosheet. An optical study suggested that the band gap energy of ZnFe2O4/RGO NCs (1.61 eV) was lower than that of pure ZnFe2O4 NPs (1.96 eV). PL spectra indicated that the recombination rate of the ZnFe2O4/ RGO NCs was lower than ZnFe2O4 NPs. MTT assay was used to evaluate the anticancer performance of ZnFe2O4 /RGO NCs and pure ZnFe2O4NPs against human cancer cells. In vitro study indicates that ZnFe2O4 /RGO NCs have higher anticancer activity against human breast (MCF-7) and lung (A549) cancer cells as compared to pure form ZnFe2O4 NPs. This work suggests that RGO doping enhances the anticancer activity of ZnFe2O4NPs by tuning its optical behavior. This study warrants future research on potential therapeutic applications of these types of nanocomposites.

8.
ACS Omega ; 8(28): 25020-25033, 2023 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-37483253

RESUMO

Graphene derivatives and metal oxide-based nanocomposites (NCs) are being studied for their diverse applications including gas sensing, environmental remediation, and biomedicine. The aim of the present work was to evaluate the effect of rGO and Bi2O3 integration on photocatalytic and anticancer efficacy. A novel Bi2O3-WO3/rGO NCs was successfully prepared via the precipitation method. X-ray crystallography (XRD) data confirmed the crystallographic structure and the phase composition of the prepared samples. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis confirmed the loading of Bi2O3-doped WO3 NPs on rGO sheets. Energy-dispersive X-ray (EDX) results confirmed that all elements of carbon (C), oxygen (O), tungsten (W), and bismuth (Bi) were present in Bi2O3-WO3/rGO NCs. The oxidation state and presence of elemental compositions in Bi2O3-WO3/rGO NCs were verified by the X-ray photoelectron spectroscopy (XPS) study. Raman spectra indicate a reduction in carbon-oxygen functional groups and an increase in the graphitic carbon percentage of the Bi2O3-WO3/rGO NCs. The functional group present in the prepared samples was examined by Fourier transform infrared (FTIR) spectroscopy. UV analysis showed that the band gap energy of the synthesized samples was slightly decreased with Bi2O3 and rGO doping. Photoluminescence (PL) spectra showed that the recombination rate of the electron-hole pair decreased with the dopants. Degradation of RhB dye under UV light was employed to evaluate photocatalytic performance. The results showed that the Bi2O3-WO3/rGO NCs have high photocatalytic activity with a degradation rate of up to 91%. Cytotoxicity studies showed that Bi2O3 and rGO addition enhance the anticancer activity of WO3 against human lung cancer cells (A549) and colorectal cancer cells (HCT116). Moreover, Bi2O3-WO3/rGO NCs showed improved biocompatibility in human umbilical vein endothelial cells (HUVECs) than pure WO3 NPs. The results of this work showed that Bi2O3-doped WO3 particles decorated on rGO sheets display improved photocatalytic and anticancer activity. The preliminary data warrants further research on such NCs for their applications in the environment and medicine.

9.
Molecules ; 28(13)2023 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-37446815

RESUMO

The incorporation of graphene with metal oxide has been widely explored in various fields, including energy storage devices, optical applications, biomedical applications, and water remediation. This research aimed to assess the impact of reduced graphene oxide (RGO) doping on the photocatalytic and anticancer properties of In2O3 nanoparticles. Pure and In2O3/RGO nanocomposites were effectively synthesized using the single-step microwave hydrothermal process. XRD, TEM, SEM, EDX, XPS, Raman, UV-Vis, and PL spectroscopy were carefully utilized to characterize the prepared samples. XRD data showed that synthesized In2O3 nanoparticles had high crystallinity with a decreased crystal size after RGO doping. TEM and SEM images revealed that the In2O3 NPs were spherical and uniformly embedded onto the surface of RGO sheets. Elemental analysis of In2O3/RGO NC confirmed the presence of In, O, and C without impurities. Raman analysis indicated the successful fabrication of In2O3 onto the RGO surface. Uv-Vis analysis showed that the band gap energy was changed with RGO addition. Raman spectra confirmed that In2O3 nanoparticles were successfully anchored onto the RGO sheet. PL results indicated that the prepared In2O3/RGO NCs can be applied to enhance photocatalytic activity and biomedical applications. In the degradation experiment, In2O3/RGO NCs exhibited superior photocatalytic activity compared to that of pure In2O3. The degradation efficiency of In2O3/RGO NCs for MB dye was up to 90%. Biological data revealed that the cytotoxicity effect of In2O3/RGO NCs was higher than In2O3 NPs in human colorectal (HCT116) and liver (HepG2) cancer cells. Importantly, the In2O3/RGO NCs exhibited better biocompatibility against human normal peripheral blood mononuclear cells (PBMCs). All the results suggest that RGO addition improves the photocatalytic and anticancer activity of In2O3 NPs. This study highlights the potential of In2O3/RGO NCs as an efficient photocatalyst and therapeutic material for water remediation and biomedicine.


Assuntos
Grafite , Nanocompostos , Humanos , Grafite/farmacologia , Grafite/química , Azul de Metileno/farmacologia , Azul de Metileno/química , Leucócitos Mononucleares , Micro-Ondas , Água , Nanocompostos/química
10.
Environ Sci Pollut Res Int ; 30(3): 6055-6067, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35986850

RESUMO

Indium oxide nanoparticles (In2O3 NPs) are being investigated for a number of applications including gas-sensing, environmental remediation, and biomedicine. We aimed to examine the effect of silver (Ag) doping on photocatalytic and anticancer activity of In2O3 NPs. The Ag-doped (2%, 4%, and 6%weight) In2O3 NPs were synthesized by the photodeposition method. Prepared samples were characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), UV-Vis spectroscopy, and the photoluminescence (PL). XRD data showed that Ag-doping increases the crystallinity of In2O3 NPs. SEM and TEM images indicated that In2O3 NPs have spherical morphology with smooth surfaces, and Ag-doping increases the size without affecting the particle's shape. XPS spectra showed the oxidation state and the presence of Ag in In2O3 NPs. Band gap energy of In2O3 NPs decreases with increasing the concentration of Ag (3.41 eV to 3.12 eV). The peak intensity of PL spectra of In2O3 NPs also reduces with the increment of Ag ions suggesting the hindrance of the recombination rate of e-/h+. The photocatalytic activity was measured by the degradation of Rh B dye under UV irradiation. The degradation efficiency of Ag-doped (6%) In2O3 NPs was 92%. Biochemical data indicated that Ag-doping enhances the anticancer performance of In2O3 NPs against human lung cancer cells (A549). Moreover, Ag-doped In2O3 NPs displayed excellent biocompatibility in normal human lung fibroblasts (IMR90). Overall, this study demonstrated that Ag-doping enhances the photocatalytic activity and anticancer efficacy of In2O3 NPs. This study warrants further investigation on the environmental and biomedical applications of Ag-In2O3 NPs.


Assuntos
Nanopartículas Metálicas , Nanopartículas , Humanos , Prata/farmacologia , Prata/química , Raios Ultravioleta , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Nanopartículas Metálicas/química
11.
Radiat Prot Dosimetry ; 198(17): 1322-1327, 2022 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-35942666

RESUMO

This study aimed to investigate the radiation risks in terms of effective dose and the cancer risk probability resulting from computed tomography (CT) scans of the head for traumatic patients and determine how often traumatic abnormalities occur. Data were collected retrospectively for 138 traumatic patients from the picture archiving and communication system, including exposure parameters and clinical findings. The mean values of the dose length product, CT dose index volume and effective dose for the CT head examinations were 787 ± 67.7 mGy•cm, 40.1 ± 1.33 mGy and 1.47 ± 0.12 mSv, respectively. Of the total cases of CT scans of the head, 57.2% (n = 79) exhibited positive findings. The cancer risk probability for the patients was 6.04 × 10-5 per procedure, with no statistically significant differences between positive and negative findings (p = 0.345). Taking into consideration the justification of the examination, the risk of missing positive findings and the radiation risks, the immediate benefit of head CT for trauma patients for guiding medical decisions outweighs the radiation risk that will probably manifest later.


Assuntos
Neoplasias , Tomografia Computadorizada por Raios X , Cabeça/diagnóstico por imagem , Humanos , Doses de Radiação , Estudos Retrospectivos , Tomografia Computadorizada por Raios X/efeitos adversos , Tomografia Computadorizada por Raios X/métodos
12.
Front Chem ; 10: 930620, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35903193

RESUMO

The use of Phyllanthus emblica (gooseberry) leaf extract to synthesize Boron-doped zinc oxide nanosheets (B-doped ZnO-NSs) is deliberated in this article. Scanning electron microscopy (SEM) shows a network of synthesized nanosheets randomly aligned side by side in a B-doped ZnO (15 wt% B) sample. The thickness of B-doped ZnO-NSs is in the range of 20-80 nm. B-doped ZnO-NSs were tested against both gram-positive and gram-negative bacterial strains including Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, and Escherichia coli. Against gram-negative bacterium (K. pneumonia and E. coli), B-doped ZnO displays enhanced antibacterial activity with 26 and 24 mm of inhibition zone, respectively. The mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), mean free path (MFP), half-value layer (HVL), and tenth value layer (TVL) of B-doped ZnO were investigated as aspects linked to radiation shielding. These observations were carried out by using a PTW® electron detector and VARIAN® irradiation with 6 MeV electrons. The results of these experiments can be used to learn more about the radiation shielding properties of B-doped ZnO nanostructures.

13.
Polymers (Basel) ; 14(10)2022 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-35631918

RESUMO

Metal oxide and graphene derivative-based nanocomposites (NCs) are attractive to the fields of environmental remediation, optics, and cancer therapy owing to their remarkable physicochemical characteristics. There is limited information on the environmental and biomedical applications of tin oxide-reduced graphene oxide nanocomposites (SnO2-rGO NCs). The goal of this work was to explore the photocatalytic activity and anticancer efficacy of SnO2-rGO NCs. Pure SnO2 NPs and SnO2-rGO NCs were prepared using the one-pot hydrothermal method. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), UV-Vis spectrometry, photoluminescence (PL), and Raman scattering microscopy were applied to characterize the synthesized samples. The crystallite size of the SnO2 NPs slightly increased after rGO doping. TEM and SEM images show that the SnO2 NPs were tightly anchored onto the rGO sheets. The XPS and EDX data confirmed the chemical state and elemental composition of the SnO2-rGO NCs. Optical data suggest that the bandgap energy of the SnO2-rGO NCs was slightly lower than for the pure SnO2 NPs. In comparison to pure SnO2 NPs, the intensity of the PL spectra of the SnO2-rGO NCs was lower, indicating the decrement of the recombination rate of the surfaces charges (e-/h+) after rGO doping. Hence, the degradation efficiency of methylene blue (MB) dye by SnO2-rGO NCs (93%) was almost 2-fold higher than for pure SnO2 NPs (54%). The anticancer efficacy of SnO2-rGO NCs was also almost 1.5-fold higher against human liver cancer (HepG2) and human lung cancer (A549) cells compared to the SnO2 NPs. This study suggests a unique method to improve the photocatalytic activity and anticancer efficacy of SnO2 NPs by fusion with graphene derivatives.

14.
Nanomaterials (Basel) ; 11(11)2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-34835679

RESUMO

Due to unique physicochemical properties, magnesium oxide nanoparticles (MgO NPs) have shown great potential for various applications, including biomedical and environmental remediation. Moreover, the physiochemical properties of MgO NPs can be tailored by metal ion doping that can be utilized in photocatalytic performance and in the biomedical field. There is limited study on the photocatalytic activity and biocompatibility of silver (Ag)-doped MgO NPs. This study was planned for facile synthesis, characterization, and photocatalytic activity of pure and silver (Ag)-doped MgO NPs. In addition, cytotoxicity of pure and Ag-doped MgO NPs was assessed in human normal umbilical vein endothelial cells (HUVECs). Pure MgO NPs and Ag-doped (1, 2, 5, and 7.5 mol%) MgO NPs were prepared via a simple sol-gel procedure. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared samples. XRD results showed the preparation of highly crystalline NPs with no impurity peaks. TEM and SEM studies indicate smooth surfaces with almost spherical morphology of MgO NPs, and Ag-doping did not change the morphology. Elemental composition study suggested that Ag is uniformly distributed in MgO particles. Intensity of the PL spectra of MgO NPs decreased with increasing the concentration of Ag dopants. In comparison to pure MgO NPs, Ag-MgO NPs showed higher degradation of methylene blue (MB) dye under UV irradiation. The improved photocatalytic activity of Ag-MgO NPs was related to the effect of dopant concentration on reducing the recombination between electrons and holes. Cytotoxicity studies showed good biocompatibility of pure and Ag-doped MgO NPs with human normal umbilical vein endothelial cells (HUVECs). These results highlighted the potential of Ag-doped MgO NPs in environmental remediation.

15.
Nanomaterials (Basel) ; 11(11)2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-34835680

RESUMO

A model is proposed to calculate the melting points of nanoparticles based on the Lennard-Jones (L-J) potential function. The effects of the size, the shape, and the atomic volume and surface packing of the nanoparticles are considered in the model. The model, based on the L-J potential function for spherical nanoparticles, agrees with the experimental values of gold (Au) and lead (Pb) nanoparticles. The model, based on the L-J potential function, is consistent with Qi and Wang's model that predicts the Gibbs-Thompson relation. Moreover, the model based on the non-integer L-J potential function can be used to predict the melting points Tm of nanoparticles.

16.
Front Oncol ; 5: 270, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26697405

RESUMO

The properties of a 50 mm × 50 mm × 30 mm monolithic LaBr3:Ce scintillator crystal coupled to a position-sensitive multi-anode photomultiplier (PMT, Hamamatsu H9500), representing the absorbing detector of a Compton camera under study for online ion (proton) beam range verification in hadron therapy, was evaluated in combination with either absorptive or reflective crystal surface coating. This study covered an assessment of the energy and position-dependent energy resolution, exhibiting a factor of 2.5-3.5 improvement for the reflectively wrapped crystal at 662 keV. The spatial dependency was investigated using a collimated (137)Cs source, showing a steep degradation of the energy resolution at the edges and corners of the absorptively wrapped crystal. Furthermore, the time resolution was determined to be 273 ps (FWHM) and 536 ps (FWHM) with reflective and absorptive coating, respectively, using a (60)Co source. In contrast, the light spread function (LSF) of the light amplitude distribution on the PMT segments improved for the absorptively wrapped detector. Both wrapping modalities showed almost no differences in the energy-dependent photopeak detection efficiency.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...