Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 49
Filtrar
1.
Environ Res ; 258: 119413, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38876422

RESUMO

Frequent detection of terbutaline in wastewater highlights its potential risks to human health associated in the environment. Exposure to terbutaline through contaminated water sources or food chain have adverse effects to human health. This work emphasized on the removal of terbutaline from wastewater using adsorption technology. Mechanochemically synthesized [Cu(INA)2] metal-organic frameworks (MOFs) and its magnetic composite ([Cu(INA)2]-MOF@Fe3O4) are designed with higher specific surface areas and tailored features to accommodate the molecular size and structure of terbutaline. Thus, batch experiment has been conducted using the [Cu(INA)2]-MOF and [Cu(INA)2]-MOF@Fe3O4 for the terbutaline adsorption. The adsorption efficiency achieved by the MOFs was 91.8% and 99.3% for the Cu(INA)2]-MOF and [Cu(INA)2]-MOF@Fe3O4 respectively. The optimum for the adsorption study included terbutaline concentration of 40 mg/L, adsorbent dose of 5 mg/L, pH of 11, temperature of 25 °C and equilibrium time of 40 min. The kinetics and isotherms have been described by pseudo-second order and Langmuir models, while the thermodynamics revealed the exothermic and spontaneous nature of the process. The promising performance of the MOFs is manifested on the ease of regeneration and reusability, achieving adsorption efficiency of 85.0% and 94.7% by the Cu(INA)2]-MOF and [Cu(INA)2]-MOF@Fe3O4, respectively at five consecutive cycles. The higher performance of the MOFs demonstrates their excellent potentialities for the terbutaline adsorption from the aqueous solution.

2.
Environ Res ; 256: 119235, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-38810826

RESUMO

Dyes are the most ubiquitous organic pollutants in industrial effluents. They are highly toxic to both plants and animals; thus, their removal is paramount to the sustainability of ecosystem. However, they have shown resistance to photolysis and various biological, physical, and chemical wastewater remediation processes. Membrane removal technology has been vital for the filtration/separation of the dyes. In comparison to polymeric membranes, inorganic and mixed matrix (MM) membranes have shown potentials to the removal of dyes. The inorganic and MM membranes are particularly effective due to their high porosity, enhanced stability, improved permeability, higher enhanced selectivity and good stability and resistance to harsh chemical and thermal conditions. They have shown prospects in filtration/separation, adsorption, and catalytic degradation of the dyes. This review highlighted the advantages of the inorganic and MM membranes for the various removal techniques for the treatments of the dyes. Methods for the membranes production have been reviewed. Their application for the filtration/separation and adsorption have been critically analyzed. Their application as support for advanced oxidation processes such as persulfate, photo-Fenton and photocatalytic degradations have been highlighted. The mechanisms underscoring the efficiency of the processes have been cited. Lastly, comments were given on the prospects and challenges of both inorganic and MM membranes towards removal of the dyes from industrial effluents.


Assuntos
Corantes , Resíduos Industriais , Membranas Artificiais , Poluentes Químicos da Água , Corantes/química , Corantes/toxicidade , Poluentes Químicos da Água/química , Poluentes Químicos da Água/análise , Resíduos Industriais/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Filtração/métodos , Adsorção
3.
Environ Res ; 252(Pt 3): 119024, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38692419

RESUMO

Environmental pollution has been increasing since last decade due to increasing industrialisation and urbanisation. Various kinds ofenvironmental pollutants including carbon dioxide (CO2), dyes, pharmaceuticals, phenols, heavy metals along with many organic and inorganic species have been discovered in the various environmental compartments which possess harmful impacts tox human health, wildlife, and ecosystems. Thus, various efforts have been made through regulations, technological advancements, and public awareness campaigns to reduce the impact of the pollution. However, finding suitable alternatives to mitigate their impacts remained a challenge. Metal-organic frameworks (MOFs) are one of the advanced materials with unique features such as high porosity and stability which exhibit versatile applications in environmental remediation. Their composites with titanium oxide nanoparticles (TiO2) have been discovered to offer potential feature such as light harvesting capacity and catalytic activity. The composite integration and properties have been confirmed through characterization using surface area analysis, scanning electron/transmission electron microscopy, atomic force microscopy, fourier transformed infrared spectroscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, thermogravimetric analysis, and others. Thus, this work rigorously discussed potential applications of the MOF@TiO2 nanomaterials for the CO2 capture and effective utilization in methanol, ethanol, acetone, acetaldehyde, and other useful products that served as fuel to various industrial processes. Additionally, the work highlights the effective performance of the materials towards photocatalytic degradation of both organic and inorganic pollutants with indepth mechanistic insights. The article will offer significant contribution for the development of sustainable and efficient technologies for the environmental monitoring and pollution mitigation.


Assuntos
Dióxido de Carbono , Estruturas Metalorgânicas , Titânio , Titânio/química , Dióxido de Carbono/química , Dióxido de Carbono/análise , Estruturas Metalorgânicas/química , Águas Residuárias/química , Recuperação e Remediação Ambiental/métodos , Nanopartículas/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/análise
4.
Environ Geochem Health ; 46(4): 145, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38568460

RESUMO

Frequent detection of sulfonamides (SAs) pharmaceuticals in wastewater has necessitated the discovery of suitable technology for their sustainable remediation. Adsorption has been widely investigated due to its effectiveness, simplicity, and availability of various adsorbent materials from natural and artificial sources. This review highlighted the potentials of carbon-based adsorbents derived from agricultural wastes such as lignocellulose, biochar, activated carbon, carbon nanotubes graphene materials as well as organic polymers such as chitosan, molecularly imprinted polymers, metal, and covalent frameworks for SAs removal from wastewater. The promising features of these materials including higher porosity, rich carbon-content, robustness, good stability as well as ease of modification have been emphasized. Thus, the materials have demonstrated excellent performance towards the SAs removal, attributed to their porous nature that provided sufficient active sites for the adsorption of SAs molecules. The modification of physico-chemical features of the materials have been discussed as efficient means for enhancing their adsorption and reusable performance. The article also proposed various interactive mechanisms for the SAs adsorption. Lastly, the prospects and challenges have been highlighted to expand the knowledge gap on the application of the materials for the sustainable removal of the SAs.


Assuntos
Nanotubos de Carbono , Águas Residuárias , Polímeros , Sulfonamidas , Sulfanilamida , Preparações Farmacêuticas
5.
Sci Rep ; 14(1): 5589, 2024 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-38453990

RESUMO

The utilization of plants for the production of metallic nanoparticles is gaining significant attention in research. In this study, we conducted phytochemical screening of Alstonia scholaris (A. scholaris) leaves extracts using various solvents, including chloroform, ethyl acetate, n-hexane, methanol, and water. Our findings revealed higher proportions of flavonoids and alkaloids in both solvents compared to other phytochemical species. In the methanol, extract proteins, anthraquinone and reducing sugar were not detected. On the other hand, the aqueous extract demonstrated the presence of amino acids, reducing sugar, phenolic compounds, anthraquinone, and saponins. Notably, ethyl acetate and chloroform extracts displayed the highest levels of bioactive compounds among all solvents. Intrigued by these results, we proceeded to investigate the antibacterial properties of the leaf extracts against two major bacterial strains, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). All extracts exhibited significant zones of inhibition against both bacterial isolates, with S. aureus showing higher susceptibility compared to E. coli. Notably, the methanol extract displayed the most potent I hibitory effect against all organisms. Inspired by the bioactivity of the methanol extract, we employed it as a plant-based material for the green synthesis of copper nanoparticles (Cu-NPs). The synthesized Cu-NPs were characterized using Fourier infrared spectroscopy (FT-IR), UV-visible spectroscopic analysis, and scanning electron microscopy (SEM). The observed color changes confirmed the successful formation of Cu-NPs, while the FTIR analysis matched previously reported peaks, further verifying the synthesis. The SEM micrographs indicated the irregular shapes of the surface particles. From the result obtained by energy dispersive X-ray spectroscopic analysis, Cu has the highest relative abundance of 67.41 wt%. Confirming the purity of the Cu-NPs colloid. These findings contribute to the growing field of eco-friendly nanotechnology and emphasize the significance of plant-mediated approaches in nanomaterial synthesis and biomedical applications.


Assuntos
Acetatos , Alstonia , Anti-Infecciosos , Nanopartículas Metálicas , Cobre/química , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus , Escherichia coli , Metanol/farmacologia , Clorofórmio/farmacologia , Extratos Vegetais/farmacologia , Extratos Vegetais/química , Anti-Infecciosos/farmacologia , Antibacterianos/química , Nanopartículas Metálicas/química , Compostos Fitoquímicos/farmacologia , Solventes/farmacologia , Açúcares/farmacologia , Antraquinonas/farmacologia , Testes de Sensibilidade Microbiana
6.
Chemosphere ; 351: 141218, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38266876

RESUMO

The widespread consumption of pharmaceutical drugs and their incomplete breakdown in organisms has led to their extensive presence in aquatic environments. The indiscriminate use of antibiotics, such as sulfonamides, has contributed to the development of drug-resistant bacteria and the persistent pollution of water bodies, posing a threat to human health and the safety of the environment. Thus, it is paramount to explore remediation technologies aimed at decomposing and complete elimination of the toxic contaminants from pharmaceutical wastewater. The review aims to explore the utilization of metal-oxide nanoparticles (MONPs) and graphitic carbon nitrides (g-C3N4) in photocatalytic degradation of sulfonamides from wastewater. Recent advances in oxidation techniques such as photocatalytic degradation are being exploited in the elimination of the sulfonamides from wastewater. MONP and g-C3N4 are commonly evolved nano substances with intrinsic properties. They possessed nano-scale structure, considerable porosity semi-conducting properties, responsible for decomposing wide range of water pollutants. They are widely applied for photocatalytic degradation of organic and inorganic substances which continue to evolve due to the low-cost, efficiency, less toxicity, and more environmentally friendliness of the materials. The review focuses on the current advances in the application of these materials, their efficiencies, degradation mechanisms, and recyclability in the context of sulfonamides photocatalytic degradation.


Assuntos
Grafite , Nanopartículas Metálicas , Compostos de Nitrogênio , Óxidos , Humanos , Sulfonamidas , Águas Residuárias , Sulfanilamida , Preparações Farmacêuticas , Catálise
7.
Chemosphere ; 343: 140223, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37734509

RESUMO

Covalent organic frameworks (COFs) are class of porous coordination polymers made up of organic building blocks joined together by covalent bonding through thermodynamic and controlled reversible polymerization reactions. This review discussed versatile applications of COFs for remediation of wastewater containing dyes, emphasizing the advantages of both pristine and modified materials in adsorption, membrane separation, and advanced oxidations processes. The excellent performance of COFs towards adsorption and membrane filtration has been centered to their higher crystallinity and porosity, exhibiting exceptionally high surface area, pore size and pore volumes. Thus, they provide more active sites for trapping the dye molecules. On one hand, the photocatalytic performance of the COFs was attributed to their semiconducting properties, and when coupled with other functional semiconducting materials, they achieve good mechanical and thermal stabilities, positive light response, and narrow band gap, a typical characteristic of excellent photocatalysts. As such, COFs and their composites have demonstrated excellent potentialities for the elimination of the dyes.

8.
Molecules ; 28(8)2023 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-37110697

RESUMO

The increased interest in the transition from liquid to solid polymer electrolytes (SPEs) has driven enormous research in the area polymer electrolyte technology. Solid biopolymer electrolytes (SBEs) are a special class of SPEs that are obtained from natural polymers. Recently, SBEs have been generating much attention because they are simple, inexpensive, and environmentally friendly. In this work, SBEs based on glycerol-plasticized methylcellulose/pectin/potassium phosphate (MC/PC/K3PO4) are investigated for their potential application in an electrochemical double-layer capacitor (EDLC). The structural, electrical, thermal, dielectric, and energy moduli of the SBEs were analyzed via X-ray diffractometry (XRD), Fourier transforms infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS), transference number measurement (TNM), and linear sweep voltammetry (LSV). The plasticizing effect of glycerol in the MC/PC/K3PO4/glycerol system was confirmed by the change in the intensity of the samples' FTIR absorption bands. The broadening of the XRD peaks demonstrates that the amorphous component of SBEs increases with increasing glycerol concentration, while EIS plots demonstrate an increase in ionic conductivity with increasing plasticizer content owing to the formation of charge-transfer complexes and the expansion of amorphous domains in polymer electrolytes (PEs). The sample containing 50% glycerol has a maximal ionic conductivity of about 7.5 × 10-4 scm-1, a broad potential window of 3.99 V, and a cation transference number of 0.959 at room temperature. Using the cyclic voltammetry (CV) test, the EDLC constructed from the sample with the highest conductivity revealed a capacitive characteristic. At 5 mVs-1, a leaf-shaped profile with a specific capacitance of 57.14 Fg-1 was measured based on the CV data.

9.
Molecules ; 28(4)2023 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-36838770

RESUMO

Presently, the rising concerns about the fossil fuel crisis and ecological deterioration have greatly affected the world economy and hence have attracted attention to the utilization of renewable energies. Among the renewable energy being developed, supercapacitors hold great promise in broad applications such as electric vehicles. Presently, the main challenge facing supercapacitors is the amount of energy stored. This, however, does not satisfy the increasing demand for higher energy storage devices, and therefore, intensive research is being undertaken to overcome the challenges of low energy density. The purpose of this review is to report on solid polymer electrolytes (SPEs) based on polyvinyl alcohol (PVA). The review discussed the PVA as a host polymer in SPEs followed by a discussion on the influence of conducting salts. The formation of SPEs as well as the ion transport mechanism in PVA SPEs were discussed. The application and development of PVA-based polymer electrolytes on supercapacitors and other energy storage devices were elucidated. The fundamentals of electrochemical characterization for analyzing the mechanism of supercapacitor applications, such as EIS, LSV and dielectric constant, are highlighted. Similarly, thermodynamic transport models of ions and their mechanism about temperature based on Arrhenius and Vogel-Tammann-Fulcher (VTF) are analyzed. Methods for enhancing the electrochemical performance of PVA-based SPEs were reported. Likely challenges facing the current electrolytes are well discussed. Finally, research directions to overcome the present challenges in producing SPEs are proposed. Therefore, this review is expected to be source material for other researchers concerned with the development of PVA-based SPE material.


Assuntos
Polímeros , Álcool de Polivinil , Etanol , Eletrólitos , Sais
10.
PLoS One ; 18(1): e0277331, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36638108

RESUMO

Most silicon carbide (SiC) MOSFET models are application-specific. These are already defined by the manufacturers and their parameters are mostly partially accessible due to restrictions. The desired characteristic of any SiC model becomes highly important if an individual wants to visualize the impact of changing intrinsic parameters as well. Also, it requires a model prior knowledge to vary these parameters accordingly. This paper proposes the parameter extraction and its selection for Silicon Carbide (SiC) power N-MOSFET model in a unique way. The extracted parameters are verified through practical implementation with a small-scale high power DC-DC 5 to 2.5 output voltage buck converter using both hardware and software emphasis. The parameters extracted using the proposed method are also tested to verify the static and dynamic characteristics of SiC MOSFET. These parameters include intrinsic, junction and overlapping capacitance. The parameters thus extracted for the SiC MOSFET are analyzed by device performance. This includes input, output transfer characteristics and transient delays under different temperature conditions and loading capabilities. The simulation and experimental results show that the parameters are highly accurate. With its development, researchers will be able to simulate and test any change in intrinsic parameters along with circuit emphasis.


Assuntos
Fontes de Energia Elétrica , Software , Simulação por Computador , Compostos Inorgânicos de Carbono
11.
Nanomaterials (Basel) ; 13(2)2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36678106

RESUMO

The applications of silver nanowires (AgNWs) are clearly relevant to their purity and morphology. Therefore, the synthesis parameters should be precisely adjusted in order to obtain AgNWs with a high aspect ratio. Consequently, controlling the reaction time versus the reaction temperature of the AgNWs is crucial to synthesize AgNWs with a high crystallinity and is important in fabricating optoelectronic devices. In this work, we tracked the morphological alterations of AgNWs during the growth process in order to determine the optimal reaction time and temperature. Thus, here, the UV-Vis absorption spectra were used to investigate how the reaction time varies with the temperature. The reaction was conducted at five different temperatures, 140-180 °C. As a result, an equation was developed to describe the relationship between them and to calculate the reaction time at any given reaction temperature. It was observed that the average diameter of the NWs was temperature-dependent and had a minimum value of 23 nm at a reaction temperature of 150 °C. A significant purification technique was conducted for the final product at a reaction temperature of 150 °C with two different speeds in the centrifuge to remove the heavy and light by-products. Based on these qualities, a AgNWs-based porous Si (AgNWs/P-Si) device was fabricated, and current-time pulsing was achieved using an ultra-violet (UV) irradiation of a 375 nm wavelength at four bias voltages of 1 V, 2 V, 3 V, and 4 V. We obtained a high level of sensitivity and detectivity with the values of 2247.49% and 2.89 × 1012 Jones, respectively. The photocurrent increased from the µA range in the P-Si to the mA range in the AgNWs/P-Si photodetector due to the featured surface plasmon resonance of the AgNWs compared to the other metals.

12.
Polymers (Basel) ; 15(2)2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36679278

RESUMO

Corrosion prevention has been a global phenomenon, particularly in metallic and construction engineering. Most inhibitors are expensive and toxic. Therefore, developing nontoxic and cheap corrosion inhibitors has been a way forward. In this work, L-arginine was successfully grafted on chitosan by the thermal technique using a reflux condenser. This copolymer was characterized by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The corrosion inhibition performance of the composite polymer was tested on mild steel in 0.5M HCl by electrochemical methods. The potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) results were consistent. The inhibition efficiency at optimum concentration rose to 91.4%. The quantum chemical calculation parameters show good properties of the material as a corrosion inhibitor. The molecular structure of the inhibitor was subjected to density functional theory (DFT) to understand its theoretical properties, and the results confirmed the inhibition efficiency of the grafted polymer for corrosion prevention.

13.
Molecules ; 27(21)2022 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-36364404

RESUMO

Leishmaniasis is one of the most neglected tropical diseases that present areal public health problems worldwide. Chemotherapy has several limitations such as toxic side effects, high costs, frequent relapses, the development of resistance, and the requirement for long-term treatment. Effective vaccines or drugs to prevent or cure the disease are not available yet. Therefore, it is important to dissect antileishmanial molecules that present selective efficacy and tolerable safety. Several studies revealed the antileishmanial activity of medicinal plants. Several organic extracts/essential oils and isolated natural compounds have been tested for their antileishmanial activities. Therefore, the aim of this review is to update and summarize the investigations that have been undertaken on the antileishmanial activity of medicinal plants and natural compounds derived, rom plants from January 2015 to December 2021. In this review, 94 plant species distributed in 39 families have been identified with antileishmanial activities. The leaves were the most commonly used plant part (49.5%) followed by stem bark, root, and whole plant (21.9%, 6.6%, and 5.4%, respectively). Other plant parts contributed less (<5%). The activity was reported against amastigotes and/or promastigotes of different species (L. infantum, L. tropica, L. major, L. amazonensis, L. aethiopica, L. donovani, L. braziliensis, L. panamensis, L. guyanensis, and L. mexicana). Most studies (84.2%) were carried out in vitro, and the others (15.8%) were performed in vivo. The IC50 values of 103 plant extracts determined in vitro were in a range of 0.88 µg/mL (polar fraction of dichloromethane extract of Boswellia serrata) to 98 µg/mL (petroleum ether extract of Murraya koenigii). Among the 15 plant extracts studied in vivo, the hydroalcoholic leaf extract of Solanum havanense reduced parasites by 93.6% in cutaneous leishmaniasis. Voacamine extracted from Tabernaemontana divaricata reduced hepatic parasitism by ≈30 times and splenic parasitism by ≈15 times in visceral leishmaniasis. Regarding cytotoxicity, 32.4% of the tested plant extracts against various Leishmania species have a selectivity index higher than 10. For isolated compounds, 49 natural compounds have been reported with anti-Leishmania activities against amastigotes and/or promastigotes of different species (L. infantum, L. major, L. amazonensis, L. donovani and L. braziliensis). The IC50 values were in a range of 0.2 µg/mL (colchicoside against promastigotes of L. major) to 42.4 µg/mL (dehydrodieuginol against promastigotes of L. amazonensis). In conclusion, there are numerous medicinal plants and natural compounds with strong effects (IC50 < 100 µg/mL) against different Leishmania species under in vitro and in vivo conditions with good selectivity indices (SI > 10). These plants and compounds may be promising sources for the development of new drugs against leishmaniasis and should be investigated in randomized clinical trials.


Assuntos
Antiprotozoários , Leishmaniose Cutânea , Plantas Medicinais , Humanos , Animais , Camundongos , Antiprotozoários/farmacologia , Antiprotozoários/uso terapêutico , Leishmaniose Cutânea/tratamento farmacológico , Compostos Fitoquímicos/farmacologia , Compostos Fitoquímicos/uso terapêutico , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Extratos Vegetais/química , Camundongos Endogâmicos BALB C
14.
PeerJ ; 10: e14075, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36275454

RESUMO

One of the largest and least documented populations of dugongs (Dugong dugon) resides in the coastal waters of the United Arab Emirates, and waters surrounding Saudi Arabia, Bahrain, and Qatar. The archaeological record of dugongs in the Gulf Region is abundant, but little is known about their fossil record in the region. Here we report an isolated sirenian rib fragment from the Futaisi Member of the Fuwayrit Formation near the town of Al Ruwais, in northern Qatar. The Fuwayrit Formation is a marine Pleistocene deposit exposed onshore in Qatar and the United Arab Emirates. Based on the correlative dating of the basal Futaisi Member with other onshore platforms, the rib fragment is approximately 125 ka. We propose that this isolated rib (likely the first rib from the right side) belongs to Dugongidae, with strong similarities to extant Dugong. We cannot, however, eliminate the possibility that it belongs to an extinct taxon, especially given its similarities with other fossil dugongid material from both Qatar and elsewhere in the world. Aside from reflecting the presence of Gulf seagrass communities in the Pleistocene, this occurrence also suggests that different (and potentially multiple) lineages of sirenians inhabited the Gulf Region in the geologic past.


Assuntos
Dugong , Fósseis , Animais , Feminino , Barein , Catar , Sirênios
15.
Molecules ; 27(17)2022 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-36080295

RESUMO

In this study, a solution casting method was used to prepare solid polymer electrolytes (SPEs) based on a polymer blend comprising polyvinyl alcohol (PVA), cellulose acetate (CA), and potassium carbonate (K2CO3) as a conducting salt, and zinc oxide nanoparticles (ZnO-NPs) as a nanofiller. The prepared electrolytes were physicochemically and electrochemically characterized, and their semi-crystalline nature was established using XRD and FESEM. The addition of ZnO to the polymer-salt combination resulted in a substantial increase in ionic conductivity, which was investigated using impedance analysis. The size of the semicircles in the Cole-Cole plots shrank as the amount of nanofiller increased, showing a decrease in bulk resistance that might be ascribed to an increase in ions due to the strong action of the ZnO-NPs. The sample with 10 wt % ZnO-NPs was found to produce the highest ionic conductivity, potential window, and lowest activation energy (Ea) of 3.70 × 10-3 Scm-1, 3.24 V, and 6.08 × 10-4 eV, respectively. The temperature-frequency dependence of conductivity was found to approximately follow the Arrhenius model, which established that the electrolytes in this study are thermally activated. Hence, it can be concluded that, based on the improved conductivity observed, SPEs based on a PVA-CA-K2CO3/ZnO-NPs composite could be applicable in all-solid-state energy storage devices.

16.
Expert Syst Appl ; 200: 116834, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-36034050

RESUMO

Classification accuracy achieved by a machine learning technique depends on the feature set used in the learning process. However, it is often found that all the features extracted by some means for a particular task do not contribute to the classification process. Feature selection (FS) is an imperative and challenging pre-processing technique that helps to discard the unnecessary and irrelevant features while reducing the computational time and space requirement and increasing the classification accuracy. Generalized Normal Distribution Optimizer (GNDO), a recently proposed meta-heuristic algorithm, can be used to solve any optimization problem. In this paper, a hybrid version of GNDO with Simulated Annealing (SA) called Binary Simulated Normal Distribution Optimizer (BSNDO) is proposed which uses SA as a local search to achieve higher classification accuracy. The proposed method is evaluated on 18 well-known UCI datasets and compared with its predecessor as well as some popular FS methods. Moreover, this method is tested on high dimensional microarray datasets to prove its worth in real-life datasets. On top of that, it is also applied to a COVID-19 dataset for classification purposes. The obtained results prove the usefulness of BSNDO as a FS method. The source code of this work is publicly available at https://github.com/ahmed-shameem/Feature_selection.

17.
Polymers (Basel) ; 14(15)2022 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-35956570

RESUMO

In this research, innovative green and sustainable solid polymer electrolytes (SPEs) based on plasticized methylcellulose/polyvinyl pyrrolidone/potassium carbonate (MC/PVP/K2CO3) were examined. The MC/PVP/K2CO3 SPE system with five distinct ethylene carbonate (EC) concentrations as a plasticizer was successfully designed. Frequency-dependent conductivity plots were used to investigate the conduction mechanism of the SPEs. Electrochemical potential window stability and the cation transfer number of the SPEs were studied via linear sweep voltammetry (LSV) and transference number measurement (TNM), respectively. Additionally, the structural behavior of the SPEs was analyzed using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD), and differential scanning calorimetry (DSC) techniques. The SPE film complexed with 15 wt.% EC measured a maximum conductivity of 3.88 × 10-4 Scm-1. According to the results of the transference number examination, cations that record a transference number of 0.949 are the primary charge carriers. An EDLC was fabricated based on the highest conducting sample that recorded a specific capacitance of 54.936 Fg-1 at 5 mVs-1.

18.
Heliyon ; 8(7): e09959, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35874070

RESUMO

This paper reports the structures, morphologies, optical properties, and photoconversion efficiency (η%) of the In2S3/ZnO core-shell heterostructures nanorod arrays (IZCSHNRAs) produced via the controlled successive ionic layer absorption and reaction (SILAR) cycles. As-produced samples were characterized using XRD, FESEM, TEM, UV-Vis, PL, XPS and FTIR techniques. The proposed IZCSHNRAs revealed nearly double photocurrent density and η% values compared to the pure ZnO nanorod arrays (ZNRAs). In addition, the light absorption, crystallinity and microstructures of the specimens were appreciably improved with the increase of the SILAR cycles. The deposited nanoparticles of In2S3 (ISNPs) on the ZNRAs surface was responsible for the improvement in the heterostructures, light absorption and photogenerated electron-hole pairs separation, thus enhancing the photoconversion performance. It is established that a simple SILAR approach can be very useful to produce good quality IZCSHNRAs-based photoelectrodes required for the future development of high performance photoelectrochemical cells (PECs).

19.
Molecules ; 27(15)2022 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-35897923

RESUMO

Successful synthesis of ZnO-chitosan nanocomposites was conducted for the removal of methylene blue from an aqueous medium. Remarkable performance of the nanocomposites was demonstrated for the effective uptake of the dye, thereby achieving 83.77, 93.78 and 97.93 mg g-1 for the chitosan, 5 wt.% ZnO-Chitosan and 10 wt.% ZnO-Chitosan, respectively. The corresponding adsorption efficiency was 88.77, 93.78 and 97.95 for the chitosan, 5 wt.% ZnO-Chitosan and 10 wt.% ZnO-Chitosan, respectively. Upon regeneration, good reusability of the nanocomposites was manifested for the continuous removal of the dye up to six consecutive cycles. The adsorption process was kinetically described by a pseudo-first order model, while the isotherms were best fitted by the Langmuir model.


Assuntos
Quitosana , Nanocompostos , Poluentes Químicos da Água , Óxido de Zinco , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Azul de Metileno , Águas Residuárias
20.
Polymers (Basel) ; 14(13)2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35808756

RESUMO

A mode-mismatched thermal lens spectrometry (TLS) technique, in a pump-probe two-laser-beam configuration, was employed for the experimental determination of the thermal properties of four selected well-characterized polyolefin homopolymer films. We investigated the thermal diffusivity (D) and thermal conductivity (κ) of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and polypropylene. We also measured the structural properties (i.e., average molecular weight, polydispersity index, branching number), along with the rheological and thermal properties (i.e., melting point, specific heat capacity Cp, degree of crystallinity) of samples by high-temperature gel permeation chromatography (HT-GPC), rheometric mechanical spectrometry (RMS), differential scanning calorimetry (DSC), and densitometry. The relationship between microstructural properties such as degree of crystallinity, D, and κ was investigated. The results show that there is good correlation between the degree of crystallinity and D. The TL technique enables measurement of D in semitransparent thin films within an uncertainty of 4%.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...