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1.
Heliyon ; 10(7): e29070, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38623235

RESUMEN

Banana pseudo-stem, often considered as an underutilized plant part was explored as a potential reinforced material to develop an eco-friendly biofilm for food packaging applications. In this study, Microcrystalline cellulose (MCC) was extracted from banana pseudo-stem by alkali and acid hydrolysis treatment. The extracted MCC was used as a reinforced material in different concentrated polyvinyl alcohol (PVA) matrix alone as well as both PVA and Carboxymethyl Cellulose (CMC) matrix to develop biofilm by solvent casting method. The synthesized MCC powder was characterized by scanning electron microscope to ensure its microcrystalline structure and to observe surface morphology. The biofilms composed of MCC, PVA, and CMC were assessed through Fourier-transform infrared spectroscopy (FTIR), mechanical properties, water content, solubility, swelling degree, moisture barrier property (Water Vapor Permeability - WVP), and light barrier property (Light Transmission and Transparency). The FTIR analysis showed the rich bonding between the materials of the biofilms. The film incorporating a combination of PVA, CMC, and MCC (S6) exhibited the highest tensile strength at 26.67 ± 0.152 MPa, making it particularly noteworthy for applications in food packaging. MCC incorporation increased the tensile strength. The WVP content of the films was observed low among the MCC-induced films which is parallel to other findings. The lowest WVP content was showed by 1% concentrated PVA with MCC (S4) (0.223 ± 0.020 10-9 g/Pahm). The WVP content of S6 film was also considerably low. MCC-incorporated films also acted as a good UV barrier. Transmittance of the MCC induced films at UV range were observed on average 38% (S2), 36% (S4) and 6% (S6) which were almost 6% lower than the control films. The S6 film demonstrated the lowest swelling capacity (1.42%) and water content, indicating a significantly low solubility of the film. The film formulated with mixing of PVA, CMC and MCC (S6) was ahead in terms of food packaging characteristics than other films. Also, the outcomes of this study point out that MCC can be a great natural resource for packaging applications and in that regard, banana pseudo-stem proves to be an excellent source for waste utilization.

2.
Ital J Food Saf ; 13(1): 10914, 2024 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-38481766

RESUMEN

Energy drinks and mango juice are popular beverages. Apart from the natural ingredients and some additives present in these drinks, sugar is an important component of both. It has been established that, other than providing sweetness, sugars are potent to bring about health consequences for their consumers. Sweeteners, both artificial (aspartame, sodium cyclamate, and saccharin) and natural (sucrose), were our centers of interest. This study aimed to determine the presence and levels of these sweeteners in energy drinks and mango juice. Spectrophotometric methods were used to determine the concentration of the mentioned sugars. For this purpose, a total of 42 samples of 7 different brands were collected from different locations in Dhaka city, Bangladesh. The methods were found to be linear over the concentration range of 10-26 µg/mL (r2=0.9989), 137-320 µg/mL (r2=0.9891), 2.5-24 µg/mL (r2=0.9915) and 2354-2784 µg/mL (r2=0.9985) for aspartame, sodium cyclamate, saccharin, and sucrose, respectively. Mango juice contained a relatively lower amount of saccharin compared to energy drinks. In the case of aspartame, one brand of energy drinks had the least amount. Moreover, both energy drinks and mango juice had a similar content of sodium cyclamate, but one brand of mango juice had a relatively low content of sodium cyclamate.

3.
Chem Rec ; 24(1): e202300228, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37857549

RESUMEN

Electrocatalytic water splitting is a promising alternative to produce high purity hydrogen gas as the green substitute for renewable energy. Thus, development of electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are vital to improve the efficiency of the water splitting process particularly based on transition metals which has been explored extensively to replace the highly active electrocatalytic activity of the iridium and ruthenium metals-based electrocatalysts. In situ growth of the material on a conductive substrate has also been proven to have the capability to lower down the overpotential value significantly. On top of that, the presence of substrate has given a massive impact on the morphology of the electrocatalyst. Among the conductive substrates that have been widely explored in the field of electrochemistry are the copper based substrates mainly copper foam, copper foil and copper mesh. Copper-based substrates possess unique properties such as low in cost, high tensile strength, excellent conductor of heat and electricity, ultraporous with well-integrated hierarchical structure and non-corrosive in nature. In this review, the recent advancements of HER and OER electrocatalysts grown on copper-based substrates has been critically discussed, focusing on their morphology, design, and preparation methods of the nanoarrays.

4.
Chem Asian J ; : e202300532, 2023 Aug 06.
Artículo en Inglés | MEDLINE | ID: mdl-37544903

RESUMEN

This study explores a water-splitting activity using a biphasic electrodeposited electrode on nickel foam (NF). The *Ni9 S8 /Cu7 S4 /NF electrode with citric acid reduction exhibits superior OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) performance with reduced overpotential and a steeper Tafel slope. The *Ni9 S8 /Cu7 S4 /NF electrode displays the ultra-low overpotential value of 212 mV for OER and 109 mV for HER at the current density of 10 mA cm-2 . The Tafel slope of 25.4 mV dec-1 for OER and 108 mV dec-1 for HER was found from that electrode. The maximum electrochemical surface area (ECSA), lowest series resistance and lowest charge transfer resistance are found in citric acid reduced electrode, showing increased electrical conductivity and quick charge transfer kinetics. Remarkably, the *Ni9 S8 /Cu7 S4 /NF electrode demonstrated excellent stability for 80 hours in pure water splitting and 20 hours in seawater splitting. The synergistic effect of using bimetallic (Cu&Ni) sulfide and enhanced electrical conductivity of the electrode are caused by reduction of metal sulfide into metallic species resulting in improved water splitting performance.

5.
Materials (Basel) ; 16(15)2023 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-37570124

RESUMEN

Compared to conventional metal oxide nanoparticles, metal oxide nanocomposites have demonstrated significantly enhanced efficiency in various applications. In this study, we aimed to synthesize zinc oxide-copper oxide nanocomposites (ZnO-CuO NCs) using a green synthesis approach. The synthesis involved mixing 4 g of Zn(NO3)2·6H2O with different concentrations of mangosteen (G. mangostana) leaf extract (0.02, 0.03, 0.04 and 0.05 g/mL) and 2 or 4 g of Cu(NO3)2·3H2O, followed by calcination at temperatures of 300, 400 and 500 °C. The synthesized ZnO-CuO NCs were characterized using various techniques, including a UV-Visible spectrometer (UV-Vis), photoluminescence (PL) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) analysis and Field Emission Scanning Electron Microscope (FE-SEM) with an Energy Dispersive X-ray (EDX) analyzer. Based on the results of this study, the optical, structural and morphological properties of ZnO-CuO NCs were found to be influenced by the concentration of the mangosteen leaf extract, the calcination temperature and the amount of Cu(NO3)2·3H2O used. Among the tested conditions, ZnO-CuO NCs derived from 0.05 g/mL of mangosteen leaf extract, 4 g of Zn(NO3)2·6H2O and 2 g of Cu(NO3)2·3H2O, calcinated at 500 °C exhibited the following characteristics: the lowest energy bandgap (2.57 eV), well-defined Zn-O and Cu-O bands, the smallest particle size of 39.10 nm with highest surface area-to-volume ratio and crystalline size of 18.17 nm. In conclusion, we successfully synthesized ZnO-CuO NCs using a green synthesis approach with mangosteen leaf extract. The properties of the nanocomposites were significantly influenced by the concentration of the plant extract, the calcination temperature and the amount of precursor used. These findings provide valuable insights for researchers seeking innovative methods for the production and utilization of nanocomposite materials.

6.
J Healthc Eng ; 2023: 1406545, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37284488

RESUMEN

Lymphoma and leukemia are fatal syndromes of cancer that cause other diseases and affect all types of age groups including male and female, and disastrous and fatal blood cancer causes an increased savvier death ratio. Both lymphoma and leukemia are associated with the damage and rise of immature lymphocytes, monocytes, neutrophils, and eosinophil cells. So, in the health sector, the early prediction and treatment of blood cancer is a major issue for survival rates. Nowadays, there are various manual techniques to analyze and predict blood cancer using the microscopic medical reports of white blood cell images, which is very steady for prediction and causes a major ratio of deaths. Manual prediction and analysis of eosinophils, lymphocytes, monocytes, and neutrophils are very difficult and time-consuming. In previous studies, they used numerous deep learning and machine learning techniques to predict blood cancer, but there are still some limitations in these studies. So, in this article, we propose a model of deep learning empowered with transfer learning and indulge in image processing techniques to improve the prediction results. The proposed transfer learning model empowered with image processing incorporates different levels of prediction, analysis, and learning procedures and employs different learning criteria like learning rate and epochs. The proposed model used numerous transfer learning models with varying parameters for each model and cloud techniques to choose the best prediction model, and the proposed model used an extensive set of performance techniques and procedures to predict the white blood cells which cause cancer to incorporate image processing techniques. So, after extensive procedures of AlexNet, MobileNet, and ResNet with both image processing and without image processing techniques with numerous learning criteria, the stochastic gradient descent momentum incorporated with AlexNet is outperformed with the highest prediction accuracy of 97.3% and the misclassification rate is 2.7% with image processing technique. The proposed model gives good results and can be applied for smart diagnosing of blood cancer using eosinophils, lymphocytes, monocytes, and neutrophils.


Asunto(s)
Neoplasias Hematológicas , Leucemia , Neoplasias , Humanos , Masculino , Femenino , Leucocitos , Aprendizaje Automático , Neoplasias/diagnóstico , Leucemia/diagnóstico , Procesamiento de Imagen Asistido por Computador/métodos
7.
RSC Adv ; 13(28): 19130-19139, 2023 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-37362330

RESUMEN

This study represents a green synthesis method for fabricating an oxygen evolution reaction (OER) electrode by depositing two-dimensional CuFeOx on nickel foam (NF). Two-dimensional CuFeOx was deposited on NF using in situ hydrothermal synthesis in the presence of Aloe vera extract. This phytochemical-assisted synthesis of CuFeOx resulted in a unique nano-rose-like morphology (petal diameter 30-70 nm), which significantly improved the electrochemical surface area of the electrode. The synthesized electrode was analyzed for its OER electrocatalytic activity and it was observed that using 75% Aloe vera extract in the phytochemical-assisted synthesis of CuFeOx resulted in improved OER electrocatalytic performance by attaining an overpotential of 310 mV for 50 mA cm-2 and 410 mV for 100 mA cm-2. The electrode also sustained robust stability throughout the 50 h of chronopotentiometry studies under alkaline electrolyte conditions, demonstrating its potential as an efficient OER electrode material. This study highlights the promising use of Aloe vera extract as a green and cost-effective way to synthesize efficient OER electrode materials.

8.
Med Dosim ; 48(4): 211-215, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37188547

RESUMEN

To investigate the feasibility of volumetric modulated arc therapy (VMAT) delivery for whole breast irradiation with a 5-fraction regimen according to the FAST-Forward trial. Recently, we treated 10 patients with carcinoma of the left breast after breast conserving surgery. The dose prescription to the PTV was 26 Gy in 5 fractions. Treatment plans were produced using a VMAT technique with the Eclipse treatment planning system for 6 MV flattening filter (FF) and FF free (FFF) beams. Dose volume histograms (DVHs) for the PTV and the organs at risk (OARs), the ipsilateral lung and heart, were compared with the dose constraints specified in the FAST-Forward trial (PTV, D95 > 95%, D5 < 105%, D2 < 107% and Dmax < 110%; ipsilateral lung, D15 < 8Gy; Heart, D30 < 1.5Gy and D5 < 7Gy). Furthermore, conformity index (CI), homogeneity index (HI) and dose to the heart, contralateral lung, contralateral breast, and left anterior descending artery (LAD), were also assessed. Mean ± SD D95(%), D5(%), D2(%), and Dmax (%) for PTV were 97.75 ± 1.12, 105.2 ± 0.82, 105.90 ± 0.89, 109.36 ± 1.00 (FF) and 96.46 ± 0.75, 103.97 ± 0.97, 104.70 ± 1.09, 108.58 ± 1.33 (FFF) respectively. The mean ± SD CI was 1.07 ± 0.05 (FF), 1.048 ± 0.06 (FFF) and HI was 0.11 ± 0.02 (FF), 0.10 ± 0.02 (FFF). Dose constraints for OARs were met for both treatment techniques. However, D15 (Gy) for ipsilateral lung was 3.0% lower with FFF beams. In contrast, D5 (Gy) for heart was 9.0% higher with FFF beams. The dose difference between FF and FFF beams for other OARs such as contralateral lung-D10 (Gy) contralateral breast-D5 (Gy) and LAD was up to 6.0%. Both FF and FFF methods met the acceptable criteria. However, the treatment plans with FFF mode were more conformal and provided greater target homogeneity.


Asunto(s)
Neoplasias Pulmonares , Radioterapia de Intensidad Modulada , Humanos , Radioterapia de Intensidad Modulada/métodos , Planificación de la Radioterapia Asistida por Computador/métodos , Dosificación Radioterapéutica , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/patología , Pulmón
9.
RSC Adv ; 13(19): 12781-12791, 2023 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-37124018

RESUMEN

NiO x as a hole transport layer (HTL) has gained a lot of research interest in perovskite solar cells (PSCs), owing to its high optical transmittance, high power conversion efficiency, wide band-gap and ease of fabrication. In this work, four different nickel based-metal organic frameworks (MOFs) using 1,3,5-benzenetricarboxylic acid (BTC), terephthalic acid (TPA), 2-aminoterephthalic acid (ATPA), and 2,5-dihydroxyterephthalic acid (DHTPA) ligands respectively, have been employed as precursors to synthesize NiO x NPs. The employment of different ligands was found to result in NiO x NPs with different structural, optical and morphological properties. The impact of calcination temperatures of the MOFs was also studied and according to field emission scanning electron microscopy (FESEM), all MOF-derived NiO x NPs exhibited lower particle size at lower calcination temperature. Upon optimization, Ni-TPA MOF derived NiO x NPs calcined at 600 °C were identified to be the best for hole transport layer application. To explore the photovoltaic performance, these NiO x NPs have been fabricated as a thin film and its structural, optical and electrical characteristics were analyzed. According to the findings, the band energy gap (E g) of the fabricated thin film has been found to be 3.25 eV and the carrier concentration, hole mobility and resistivity were also measured to be 6.8 × 1014 cm-3; 4.7 × 1014 Ω cm and 2.0 cm2 V-1 s-1, respectively. Finally, a numerical simulation was conducted using SCAPS-1D incorporating the optical and electrical parameters from the thin film analysis. FTO/TiO2/CsPbBr3/NiO x /C has been utilized as the device configuration which recorded an efficiency of 13.9% with V oc of 1.89 V, J sc of 11.07 mA cm-2, and FF of 66.6%.

10.
Heliyon ; 9(3): e14438, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36950573

RESUMEN

Transition metal di-chalcogenides (TMCDs)-Tungsten disulfide (WS2) exhibit excellent optoelectronic properties such as suitable bandgap, high absorption coefficient, good conductivity, high carrier mobility, etc. to be used as a photovoltaic material for thin-film solar cells. In the present work, we have replaced the traditional buffer CdS and ITO/ZnO window layer in CdTe solar cells with the non-toxic, earth-abundant WS2 buffer and SnO2 window layer, respectively. The SCAPS-1D solar simulator is used to investigate the potentiality of WS2 as buffer material in CdTe solar cells. This numerical study provides a comparison of the performances between the proposed structure: SnO2/WS2/CdTe/Au and the baseline structure: ITO/ZnO/CdS/CdTe/Au. The impacts of the charge carrier generation rate, spectral response, current-voltage characteristics, bulk defect density, defect density at buffer/absorber interface, operating temperature, and capacitance-voltage characteristics on the solar cell performance parameters have also been analyzed. The tolerance level of defect density in WS2 bulk and WS2/CdTe interface are found to be 1017 cm-3 and 1012 cm-3, respectively. The temperature study reveals the poor structural robustness and thermal stability of the proposed cell. The conversion efficiency of the proposed cell has found to be 20.55% at the optimized device structure. Nevertheles, these findings may provide an insight to fabricate viable, environment friendly, and inexpensive CdTe thin-film solar cells.

11.
Heliyon ; 8(11): e11719, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36425430

RESUMEN

In this work, an ultra-thin (0.815 µm) lead-free all-inorganic novel PV cell structure consisting of solid-state layers with the configuration SnO2/ZnOS/CsGeI3/CZTSe/Au has been optimized using SCAPS-1D simulator. ZnOS electron transport layer (ETL) has been deployed and various hole transport layer (HTL) material candidates have been considered to find the most suitable one in order to get the maximum possible power conversion efficiency (PCE). The simulation begins with the optimization of the thickness of the ZnOS buffer layer, followed by an analysis of HTL and ETL doping concentrations, thickness and bandgap optimization of absorber layer. The maximum permissible defect density at the ZnOS/CsGeI3 interface and the bulk defect density of the absorber layer (CsGeI3) are also investigated. It is also found that when the temperature rises, short circuit current density (J sc ) rises by 1.43 mA/K and open-circuit voltage (V oc ) degrades by 2 mV/K. The optimized structure results in a PCE of 26.893% with J sc , V oc , and fill factor (FF) of 28.172 mA cm-2, 1.0834 V, and 88.107% respectively. The cell performance parameters outperform those found in the recent literature. The simulated results of the proposed configuration are expected to be a helpful reference for the future implementation of a cost-effective and efficient all-inorganic perovskite PV cell.

12.
Nanomaterials (Basel) ; 12(19)2022 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-36234594

RESUMEN

Tungsten oxide (WOx) thin films were synthesized through the RF magnetron sputtering method by varying the sputtering power from 30 W to 80 W. Different investigations have been conducted to evaluate the variation in different morphological, optical, and dielectric properties with the sputtering power and prove the possibility of using WOx in optoelectronic applications. An Energy Dispersive X-ray (EDX), stylus profilometer, and atomic force microscope (AFM) have been used to investigate the dependency of morphological properties on sputtering power. Transmittance, absorbance, and reflectance of the films, investigated by Ultraviolet-Visible (UV-Vis) spectroscopy, have allowed for further determination of some necessary parameters, such as absorption coefficient, penetration depth, optical band energy gap, refractive index, extinction coefficient, dielectric parameters, a few types of loss parameters, etc. Variations in these parameters with the incident light spectrum have been closely analyzed. Some important parameters such as transmittance (above 80%), optical band energy gap (~3.7 eV), and refractive index (~2) ensure that as-grown WOx films can be used in some optoelectronic applications, mainly in photovoltaic research. Furthermore, strong dependencies of all evaluated parameters on the sputtering power were found, which are to be of great use for developing the films with the required properties.

13.
Nanomaterials (Basel) ; 12(20)2022 Oct 13.
Artículo en Inglés | MEDLINE | ID: mdl-36296778

RESUMEN

Synthesis of copper oxide (CuO) nanostructures via biological approach has gained attention to reduce the harmful effects of chemical synthesis. The CuO nanostructures were synthesized through a green approach using the Garcinia mangostana L. leaf extract and copper (II) nitrate trihydrate as a precursor at varying calcination temperatures (200-600 °C). The effect of calcination temperatures on the structural, morphological and optical properties of CuO nanostructures was studied. The red shifting of the green-synthesized CuO nanoparticles' absorption peak was observed in UV-visible spectrum, and the optical energy bandgap was found to decrease from 3.41 eV to 3.19 eV as the calcination temperatures increased. The PL analysis shown that synthesized CuO NPs calcinated at 500 °C has the maximum charge carriers separation. A peak located at 504-536 cm-1 was shown in FTIR spectrum that indicated the presence of a copper-oxygen vibration band and become sharper and more intense when increasing the calcination temperature. The XRD studies revealed that the CuO nanoparticles' crystalline size was found to increase from 12.78 nm to 28.17 nm, and dislocation density decreased from 61.26 × 1014 cm-1 to 12.60 × 1014 cm-1, while micro strain decreased from 3.40 × 10-4 to 1.26 × 10-4. From the XPS measurement, only CuO single phase without impurities was detected for the green-mediated NPs calcinated at 500 °C. The morphologies of CuO nanostructures were examined using FESEM and became more spherical in shape at elevated calcination temperature. More or less spherical nanostructure of green-mediated CuO calcinated at 500 °C were also observed using TEM. The purity of the green-synthesized CuO nanoparticles was evaluated by EDX analysis, and results showed that increasing calcination temperature increases the purity of CuO nanoparticles.

14.
J Behav Exp Finance ; 36: 100747, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36065258

RESUMEN

The paper examines how various COVID-19 COVID-19 news sentiments differentially impact the behaviour of cryptocurrency returns. We used a nonlinear technique of transfer entropy to investigate the relationship between the top 30 cryptocurrencies by market capitalisation and COVID-19 COVID-19 news sentiment. Results show that COVID-19 COVID-19 news sentiment influences cryptocurrency returns. The nexus is unidirectional from news sentiment to cryptocurrency returns, in contrast to past findings. These results have practical implications for policymakers and market participants in understanding cryptocurrency market dynamics under extremely stressful market conditions. .

15.
Nanomaterials (Basel) ; 12(11)2022 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-35683787

RESUMEN

In this study, lead sulfide (PbS) nanoparticles were synthesized by the chemical precipitation method using Aloe Vera extract with PbCl2 and Thiourea (H2N-CS-NH2). The synthesized nanoparticles have been investigated using x-ray diffraction (XRD), UV-Vis, energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD and TEM results confirm that the films are in the cubic phase. The crystallite size, lattice constant, micro-strain, dislocation density, optical bandgap, etc. have been determined using XRD and UV-Vis for investigating the quality of prepared nanoparticles. The possible application of these synthesized nanoparticles in the solar cells was investigated by fabricating the thin films on an FTO-coated and bare glass substrate. The properties of nanoparticles were found to be nearly retained in the film state as well. The experimentally found properties of thin films have been implemented for perovskite solar cell simulation and current-voltage and capacitance-voltage characteristics have been investigated. The simulation results showed that PbS nanoparticles could be a potential hole transport layer for high-efficiency perovskite solar cell applications.

16.
J Int Dev ; 34(4): 898-918, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35571228

RESUMEN

This study provides new evidence on how risk spillovers occur from the United States to developing economies in Africa during the COVID-19 pandemic. The results show that downside risk exposures of African markets, financial firms and banks particularly increased during Phase I (30 January to 30 April 2020). The nature and magnitude of downside risk exposures of African financial markets were similar to those of the United States. Our results also reveal that the United States is a net transmitter of risk spillovers while Nigeria, South Africa, Egypt and Morocco are net recipients. Our conclusions offer guidance to risk managers, policymakers and investors.

17.
Financ Res Lett ; 47: 102787, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35291226

RESUMEN

We use the Conditional Value-at-Risk (CoVaR) model to develop the systemic contagion index (SCI) for cryptocurrencies and examine their spillover effects. The SCI exhibits the highest value during the COVID-19 period, indicating evidence of pandemic-driven contagion channels. Similarly, cryptocurrency systemic networks show that the COVID-19 period induced increased interconnections, highlighting a higher number of systemic contagion channels. Our study has practical implications for investors to identify the systemic vulnerability of each cryptocurrency and make informed decisions during the crisis and non-crisis periods.

18.
Financ Res Lett ; 45: 102170, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-35221818

RESUMEN

This study examines the dynamic connectedness between COVID-19 media coverage index (MCI) and ESG leader indices. Our findings provide evidence that MCI plays a role in facilitating the transmission of contagion to advanced and emerging equity markets during the pandemic. The connectedness between MCI and ESG leader indices is more pronounced around March and April 2020 at the peak of the pandemic. The US is a net receiver of shocks reaffirming that it was the most affected country during the pandemic. Our results provide implications for investors, portfolio managers, and policymakers in mitigating financial risks during the pandemic.

19.
Nanomaterials (Basel) ; 11(12)2021 Dec 20.
Artículo en Inglés | MEDLINE | ID: mdl-34947812

RESUMEN

Perovskite solar cells (PSCs) have already achieved efficiencies of over 25%; however, their instability and degradation in the operational environment have prevented them from becoming commercially viable. Understanding the degradation mechanism, as well as improving the fabrication technique for achieving high-quality perovskite films, is crucial to overcoming these shortcomings. In this study, we investigated details in the changes of physical properties associated with the degradation and/or decomposition of perovskite films and solar cells using XRD, FESEM, EDX, UV-Vis, Hall-effect, and current-voltage (I-V) measurement techniques. The dissociation, as well as the intensity of perovskite peaks, have been observed as an impact of film degradation by humidity. The decomposition rate of perovskite film has been estimated from the structural and optical changes. The performance degradation of novel planner structure PSCs has been investigated in detail. The PSCs were fabricated in-room ambient using candle soot carbon and screen-printed Ag electrode. It was found that until the perovskite film decomposed by 30%, the film properties and cell efficiency remained stable.

20.
Polymers (Basel) ; 13(21)2021 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-34771242

RESUMEN

This study explores the possibility of transforming lignocellulose-rich agricultural waste materials into value-added products. Cellulose was extracted from an empty fruit bunch of oil palm and further modified into carboxymethyl cellulose (CMC), a water-soluble cellulose derivative. The CMC was then employed as the polymeric content in fabrication of solid polymer electrolyte (SPE) films incorporated with lithium iodide. To enhance the ionic conductivity of the solid polymer electrolytes, the compositions were optimized with different amounts of glycerol as a plasticizing agent. The chemical and physical effects of plasticizer content on the film composition were studied by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. FTIR and XRD analysis confirmed the interaction plasticizer with the polymer matrix and the amorphous nature of fabricated SPEs. The highest ionic conductivity of 6.26 × 10-2 S/cm was obtained with the addition of 25 wt % of glycerol. By fabricating solid polymer electrolytes from oil palm waste-derived cellulose, the sustainability of the materials can be retained while reducing the dependence on fossil fuel-derived materials in electrochemical devices.

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