A viable hydrothermal technique has been explored for the synthesis of copper doped Zinc oxide nanoparticles (Cu-doped ZnO-NPs) based on the precursor's mixture of Copper-II chloride dihydrate ...(CuCl2.2H2O), Zinc chloride (ZnCl2), and potassium hydroxide (KOH). X-ray diffraction (XRD) reported the hexagonal wurtzite structure of the synthesized Cu-doped ZnO-NPs. The surface morphology is checked via field emission scanning electron microscopy (FE-SEM), whereas, the elemental compositions of the samples were confirmed by Raman, and X-ray photoelectron spectroscopy (XPS), respectively. The as-obtained ZnO-NPs and Cu-doped ZnO-NPs were then tested for their antibacterial activity against clinical isolates of Gram-positive (Staphylococcus aureus, Streptococcus pyogenes) and Gram-negative (Escherichia coli, Klebsiella pneumonia) bacteria via agar well diffusion method. The zone of inhibition (ZOI) for Cu-doped ZnO-NPs was found to be 24 and 19 mm against S. Aureus and S. pyogenes, and 18 and 11 mm against E. coli and K. pneumoniae, respectively. The synthesized Cu-doped ZnO-NPs can thus be found as a potential nano antibiotic against Gram-positive multi-drug resistant bacterial strains.
This study adds to the inconclusive debate on safe-haven properties of cryptocurrencies during Covid-19 by analyzing the use of wavelet coherence framework on the global Covid-19 fear index, ...cryptocurrency implied volatility index (VCRIX), and cryptocurrency returns. Our findings show that a non-financial market-based proxy of market stress that represents fear of households and retail investors reveals cryptocurrencies as safe-haven assets; however, a financial market-based proxy of market turbulence exposes that cryptocurrencies behave like traditional assets during the times of Covid-19 pandemic. Our findings support that long-term investors can invest in the cryptocurrency market to hedge the risks during Covid-19 pandemic.
Are ESG stocks safe-haven during COVID-19? Rubbaniy, Ghulame; Khalid, Ali Awais; Rizwan, Muhammad Faisal ...
Studies in economics and finance (Charlotte, N.C.),
02/2022, Letnik:
39, Številka:
2
Journal Article
Recenzirano
Purpose
The purpose of this study is to investigate safe-haven properties of environmental, social and governance (ESG) stocks in global and emerging ESG stock markets during the times of COVID-19 so ...that portfolio managers and equity market investors could decide to use ESG stocks in their portfolio hedging strategies during times of health and market crisis similar to COVID-19 pandemic.
Design/methodology/approach
The study uses a wavelet coherence framework on four major ESG stock indices from global and emerging stock markets, and two proxies of COVID-19 fear over the period from 5 February 2020 to 18 March 2021.
Findings
The results of the study show a positive co-movement of the global COVID-19 fear index (GFI) with ESG stock indices on the frequency band of 32 to 64 days, which confirms hedging and safe-haven properties of ESG stocks using the health fear proxy of COVID-19. However, the relationship between all indices and GFI is mixed and inconclusive on a frequency of 0–8 days. Further, the findings do not support the safe-haven characteristics of ESG indices using the market fear proxy (IDEMV index) of COVID-19. The robustness analysis using the CBOE VIX as a proxy of market fear supports that ESG indices do not possess safe-haven properties. The results of the study conclude that the safe-haven properties of ESG indices during the ongoing COVID-19 pandemic is contingent upon the proxy of COVID-19 fear.
Practical implications
The findings have important implications for the equity investors and assetty managers to improve their portfolio performance by including ESG stocks in their portfolio choice during the COVID-19 pandemic and similar health crisis. However, their investment decisions could be affected by the choice of COVID-19 proxy.
Originality/value
The authors believe in the originality of the paper due to following reasons. First, to the best of the knowledge, this is the first study investigating the safe-haven properties of ESG stocks. Second, the authors use both health fear (GFI) and market fear (IDEMV index) proxies of COVID-19 to compare whether safe-haven properties are characterized by health fear or market fear due to COVID-19. Finally, the authors use the wavelet coherency framework, which not only takes both time and frequency dimensions of the data into account but also remains unaffected by data stationarity and size issues.
Cobalt (Co) doped zinc oxide (ZnO) microcrystals (MCs) are prepared by using the hydrothermal method from the precursor's mixture of zinc chloride (ZnCl
), cobalt-II chloride hexahydrate (CoCl
·6H
...O), and potassium hydroxide (KOH). The smooth round cylindrical morphologies of the synthesized microcrystals of Co-doped ZnO show an increase in absorption with the cobalt doping. The antibacterial activity of the as-obtained Co-doped ZnO-MCs was tested against the bacterial strains of gram-negative (
,
) and gram-positive bacteria (
,
) via the agar well diffusion method. The zones of inhibition (ZOI) for Co-doped ZnO-MCs against
and
were found to be 17 and 19 mm, and 15 and 16 mm against
and
, respectively. The prepared Co-doped ZnO-MCs were thus established as a probable antibacterial agent against gram-negative bacterial strains.
In this study, successful synthesis of ZnO nanoparticles (NPs), CuO NPs, and ZnO/CuO nanocomposite through an eco-friendly method using Corriandrum sativum leaf extract as a capping agent is ...reported. Using XRD, FTIR, UV-Vis, and SEM techniques, the synthesized materials were characterized for structural analysis, functional groups identification, spectroscopic measurements, and morphological analysis. The percentage composition and purity of the samples were determined by using Energy Dispersive X-ray (EDX), which showed the synthesis of materials. Morphological analysis was done by Scanning Electron Microscopy (SEM) which reflected that the CuO NPs, ZnO NPs and ZnO/CuO nanocomposite were spherical, and the average size calculated by using Image J software was around 25 nm, 55 nm, and 11 nm, respectively. FTIR and UV-Vis analyses were used for synthetic confirmation through characteristic peaks of materials. The synthesized (ZnO, CuO, and CuO/ZnO) nanomaterials were evaluated for photocatalytic activity using methylene blue (MB) dye. Among all three photocatalysts, the composite showed maximum photodegradation compared to the other two materials. The present work could lead to a pathway for the decontamination of harmful dyes of wastewater released from different industries.
Water salinity causes less production of agricultural productivity, low economic returns, soil destructions, less sustainability, and reduction in the germination rate. The current study was aimed to ...understand the combined potential of halophilic bacteria and rice husk in treating water salinity. In total, 10 halophilic bacterial isolates were isolated from Khewra Mines, Pakistan. Bacterial isolates were characterized by biochemical tests. 16S rRNA gene sequencing identified the isolate SO 1 as Bacillus safensis (accession number ON203008) being the promising halophilic bacteria tolerating upto 3 M NaCl concentration. Next, rice husk was used as carbon source for bacterial biofilm formation, growth and propagation. For saline water treatment, the experimental setting comprising glass wool, rice husk and artificial sea water (3 M) was set. B. safensis biofilm was developed in test samples to desaline the saline water containing 3 M NaCl concentration. Following NaCl decline, flame photometric analysis was used to check the desalination extent of treated saline water. Results showed decreased sodium level in sea water in the presence of rice husk and glass wool. The eluted water used for the germination of Zea mays seeds showed improved growth performance. Also, decreased photosynthetic pigments (chlorophyll “a” = 18.99, and chlorophyll “b” = 10.65), sugar contents (0.7593), and increased carotenoid (1526.91), protein contents (0.4521) were noted compared to control. This eco‐friendly approach for bioremediation of salt‐affected soils to optimize crop yields under stress through halophilic bacteria and rice husk may overcome the problem of the reduced yield of cash crops/agriculture and water shortage by salinity.
In this study, zinc-oxide (ZnO) nanoparticles (NPs) doped with cobalt (Co) were synthesized using a simple coprecipitation technique. The concentration of Co was varied to investigate its effect on ...the structural, morphological, optical, and dielectric properties of the NPs. X-ray diffraction (XRD) analysis confirmed the hexagonal wurtzite structure of both undoped and Co-doped ZnO-NPs. Scanning electron microscopy (SEM) was used to examine the morphology of the synthesized NPs, while energy-dispersive X-ray spectroscopy (EDX) was used to verify their purity. The band gap of the NPs was evaluated using UV-visible spectroscopy, which revealed a decrease in the energy gap as the concentration of Co2+ increased in the ZnO matrix. The dielectric constants and AC conductivity of the NPs were measured using an LCR meter. The dielectric constant of the Co-doped ZnO-NPs continuously increased from 4.0 x 10.sup.-9 to 2.25 x 10.sup.-8, while the dielectric loss decreased from 4.0 x 10.sup.-8 to 1.7 x 10.sup.-7 as the Co content increased from 0.01 to 0.07%. The a.c. conductivity also increased with increasing applied frequency. The findings suggest that the synthesized Co-doped ZnO-NPs possess enhanced dielectric properties and reduced energy gap, making them promising candidates for low-frequency devices such as UV photodetectors, optoelectronics, and spintronics applications. The use of a cost-effective and scalable synthesis method, coupled with detailed material characterization, makes this work significant in the field of nanomaterials and device engineering.
Environmental problems with chemical and biological water pollution have become a major concern for society. Providing people with safe and affordable water is a grand challenge of the 21st century. ...The study investigates the photocatalytic degradation capabilities of hydrothermally prepared pure and Cu-doped ZnO nanoparticles (NPs) for the elimination of dye pollutants. A simple, cost-effective hydrothermal process is employed to synthesize the Cu-doped ZnO NPs. The photocatalytic dye degradation activity of the synthesized Cu-doped ZnO NPs is tested by using methylene blue (MB) dye. In addition, the parameters that affect photodegradation efficiency, such as catalyst concentration, starting potential of hydrogen (pH), and dye concentration, were also assessed. The dye degradation is found to be directly proportional to the irradiation time, as 94% of the MB dye is degraded in 2 hrs. Similarly, the dye degradation shows an inverse relation to the MB dye concentration, as the degradation reduced from 94% to 20% when the MB concentration increases from 5 ppm to 80 ppm. The synthesized cost-effective and environmentally friendly Cu-doped ZnO NPs exhibit improved photocatalytic activity against MB dye and can therefore be employed in wastewater treatment materials.
In this study Fe-Cu supported on Alginate-limestone (Fe-Cu/Alg-LS) was prepared. The increase in surface area was the main motivation for the synthesis of ternary composites. Scanning electronic ...microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used to examine the surface morphology, particle size, percentage of crystallinity, and elemental content of the resultant composite. Fe-Cu/Alg-LS was used as an adsorbent for the removal of drugs such as ciprofloxacin (CIP) and levofloxacin (LEV)from contaminated medium. The adsorption parameters were computed using kinetic and isotherm models. The maximum removal efficiency of CIP (20 ppm) and LEV (10 ppm) was found to be 97.3% and 100%, respectively. The optimal conditions were pH 6 and 7 for CIP and LEV, optimum contact time 45, 40 min for CIP and LEV, and temperature of 303 K. The pseudo-second-order model, which confirmed the chemisorption properties of the process, was the most appropriate kinetic model among the ones used, and the Langmuir model, which was the most appropriate isotherm model. Moreover, the parameters of thermodynamics were also assessed. The results imply that the synthesized nanocomposites can be used to remove hazard materials from aqueous solutions.
Using a panel smooth transition regression framework on a new proxy of the business cycle (BC) index and quarterly data of US bank holding companies from 1993Q1 to 2020Q1, our results provide ...empirical support for the theory that the BC has a nonlinear effect on liquidity creation. We find a positive and highly significant nonlinear effect of the BC on liquidity creation, which not only supports the pro‐cyclicality of liquidity creation but also improves the liquidity creation estimation compared to previous studies. The results are robust to different proxies of the BC and model specifications. We also document that US bank holding companies create liquidity more during the expansion phase (normal times) than during the recession phase (crisis times) of the BC, suggesting an asymmetrical effect of BC changes on liquidity creation. Our findings have important implications for financial market participants by suggesting that banks should keep alternative sources of funding on hand during the BC recession phase. Insights from our study also provide policy implications for central banks and prudent supervisors to consider when incentivizing banks, for instance, by lowering regulatory requirements, adjusting the policy rate, or implementing any other quantitative easing policy during the BC recession phase to keep the financial system efficient.
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