Without remorse, fossil fuels have made a huge contribution to global development in all of its forms. However, the recent scientific outlooks are currently shifting as more research is targeted ...towards promoting a carbon-free economy in addition to the use of electric power from renewable sources. While renewable energy sources may be a solution to the anthropogenic greenhouse gas (GHG) emissions from fossil fuel they are yet season-dependent faced with major atmospheric drawbacks which when combined with annually varying, but steady, energy demand, results in renewable energy excesses or deficits. Therefore, it is essential to devise a long-term storage medium to balance their intermittent demand and supply. Hydrogen (H2) as an energy vector has been suggested as a viable method of achieving the objectives of meeting the increasing global energy demand. However, successful implementation of a full-scale H2 economy requires large-scale H2 storage (as H2 is highly compressible). As such, storage of H2 in geological formations has been considered as a potential solution where it can be withdrawn again at the larger stage for utilization. Thus, in this review, we focus on the potential use of geological formations for large-scale underground hydrogen storage (UHS) where both conventional and non-conventional UHS options were examined in depth. Also, insights into some of the probable sites, and the related examined criteria for selection were highlighted. The hydrodynamics of UHS influencing factors (including solid, fluid, and solid–fluid interactions) are summarized exclusively. In addition, the economics and reaction perspectives inherent to UHS have been examined. The findings of this study show that UHS, like other storage systems, is still in its infancy. Further research and development are needed to address the significant hurdles and research gaps found, particularly in replaceable influencing parameters. As a result, this study is a valuable resource for UHS researchers.
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•Comprehensive review of underground hydrogen storage (UHS).•Potential storage sites and criteria.•Hydrodynamics of the multiple influencing parameters affecting UHS.•UHS reactions.•Challenges and open research opportunities for future studies.
This paper investigates the relationship between measures of intellectual capital efficiency and the performance of the listed banks in Bangladesh. We have collected data from the listed bank's ...published annual reports for seven years (2015–2021). We have primarily used standard panel data analysis techniques to assess the static relationships. In addition, to the static models, we have also checked the dynamic models for robustness in the context of Bangladesh. Following the RBV (Resource Based theory), we have found that the MVAIC (Modified Value-Added Intellectual Coefficient) significantly and positively determines firm performance in both static and dynamic methods. However, various components of MVAIC show differing relationships, which indicates that the two-step system GMM (Generalized Method of Moments) is superior to static models. The moderating role of MEETING (Company Meetings) is significant with respect to MVAIC. In addition, the moderating role of corporate governance variables at the component level remained the same in both methods. Our further analysis of the association with respect to the before and during pandemic periods suggests that the relationship remains the same irrespective of the period under study. Future research can use this paper to understand the significance of dynamic modeling while studying IC (Intellectual Capital) in an emerging economy context. This is among a few studies that have applied both static and dynamic models to assess the relationship between IC and firm performance in the context of emerging economies. Policymakers and bank managers in Bangladesh could use the findings of this study to realize that IC is much more valuable than other available tangible assets in creating a sustainable competitive advantage.
•Chitosan-based nanofibers are promising materials for the treatment of wastewater.•Chitosan can be functionalized with various functionalities and therefore can adsorb different pollutants.•In ...nanofibers surface area increase leading to increase adsorption efficiency.•Crosslinking process gives the chitosan-based nanofiber much strength, which is favorable for an adsorbent.•Chitosan-based nanofibers could be transformed into various composites, membranes, films etc. facilitates for wastewater treatment.
Now-a-days water pollution is one of the most concerned problem as it is increasing due to industrialization and human activities. The applications of electrospun nanofibers are increasing day by day due to their special properties such as huge surface-to-volume ratio, possibilities of surface modification and conversion to small mesh mat or membrane etc. Chitosan-based electrospun nanofibers have more avenues due to their additional benefits of non-toxicity, biocompatibility, biodegradability and cost-effectiveness. Although chitosan-based nanofibers have been using in various biomedical fields and reviewed, applications as adsorbents for the removal of heavy metals, dyes and other pollutants are relatively new and not reviewed yet. In this regard, the present review explores various types of chitosan-based nanofibers prepared with pure chitosan, mixed with other materials, surface-modified chitosan, magnetic chitosan etc., their adsorption performance and applications for the removal of heavy metals, dyes, and miscellaneous pollutants.
In recent years, there has been increasing interest in developing green biocomposite for industrial wastewater treatment. In this study, prawn-shell-derived chitosan (CHT) and kaolinite rich modified ...clay (MC) were used to fabricate biocomposite beads with different compositions. Prepared composite beads were characterized by FTIR, and XRD, and SEM. The possible application of the beads was evaluated primarily by measuring the adsorption efficiency in standard models of lead (II) and methylene blue (MB) dye solution, and the results show a promising removal efficiency. In addition, the composites were used to remove Cr (VI), Pb (II), and MB from real industrial effluents. From tannery effluent, 50.90% of chromium and 39.50% of lead ions were removed by composites rich in chitosan and 31.50% of MB was removed from textile effluent by a composite rich in clay. Moreover, the composite beads were found to be activated in both acidic and basic media depending on their composition, which gives a scope to their universal application in dye and heavy metal removal from wastewater from various industries.
The recent pandemic and aftermath debate regarding bank interest margins deserve special attention and have become policy dialogue in emerging economies. However, the previous literature's findings ...were largely inconclusive and ignored influential variables such as the impact of default risk on bank interest margins. Using a two-step system GMM estimation considering 32 Bangladeshi commercial banks from 2000 to 2022, we produce robust evidence that higher regulatory capital restrictions reduce the bank interest margin, while increased default risk induces the bank interest margin. The impact intensity during the COVID pandemic is higher than in the pre-COVID period. Moreover, we find the synergy effect of regulatory capital and default risk assists in reducing the bank interest margin. Bank margin persistently fell during the capital market crash period, whereas it rose in the financial crisis period. We cast several robustness tests to confirm our main findings. These findings could generate important implications for bank stakeholders and policymakers.
This study describes the fabrication of nanocomposites using electrospinning technique from poly lactic acid (PLA) and nano-hydroxyapatite (n-HAp). The prepared electrospun PLA-nHAP nanocomposite is ...intended to be used for drug delivery application. A hydrogen bond in between nHAp and PLA was confirmed by Fourier transform infrared (FT-IR) spectroscopy. Degradation study of the prepared electrospun PLA-nHAp nanocomposite was conducted for 30 days both in phosphate buffer solution (PBS) of pH 7.4 and deionized water. The degradation of the nanocomposite occurred faster in PBS in comparison to water. Cytotoxicity analysis was conducted on both Vero cells and BHK-21 cells and the survival percentage of both cells was found to be more than 95%, which indicates that the prepared nanocomposite is non-toxic and biocompatible. Gentamicin was loaded in the nanocomposite via an encapsulation process and the in vitro drug delivery process was investigated in phosphate buffer solution at different pHs. An initial burst release of the drug was observed from the nanocomposite after 1 to 2 weeks for all pH media. After that, a sustained drug release behavior was observed for the nanocomposite for 8 weeks with a release of 80%, 70% and 50% at pHs 5.5, 6.0 and 7.4, respectively. It can be suggested that the electrospun PLA-nHAp nanocomposite can be used as a potential antibacterial drug carrier for sustained drug release in dental and orthopedic sector.
A new approach for extracting fat from tannery fleshing wastes (TFW) was established by hydrolyzing in water using a crude neutral protease enzyme. The bacterial strain for protease preparation was ...isolated from the waste dumping site of Institute of Leather Engineering and Technology of the University of Dhaka. The crude enzyme thus obtained was found highly active at 55 °C and pH 8.0, with a substrate concentration of 2%. Several reaction parameters, such as enzyme concentration, hydrolysis temperature and duration, were optimized using response surface methodology (RSM). The detailed analysis data by RSM showed 31.33% enzyme to dry weight of fleshing, 2.874 h of hydrolysis, and at 65.23 °C temperature to be the optimum for maximum theoretical fat yield of 38.46%. The laboratory experiments under optimum conditions resulted 34.9% fat yield with an error of 10.17%. The fleshing fat was transesterified in methanol into biodiesel using a recyclable magnetic nano catalyst with a 98% conversion and glycerol as a byproduct. The FT-IR spectroscopic results demonstrated an absorption of CO stretching at 1740 cm−1 for α, β-unsaturated esters in the biodiesel and its fatty acid ethyl ester. The 1H-NMR spectroscopy revealed a singlet peak of methoxy protons at 3.65 ppm and a triplet at 2.26–2.30 ppm for α-CH2 protons that confirmed the presence of unsaturated fatty acids with a carbonyl hydrogen double bond peak at 2.00–2.01 ppm. The GC-MS data of the biodiesel comprises of ethyl E−11-hexa-decanoate, ethyl myristate, palmitate, stearate, and decanoate. The results of various fuel parameters of the biodiesel were measured and compared with standard biodiesel EN14214 which revealed that it has comparable fuel properties to the standard. The higher calorific value (38.5 MJ kg−1) and flash point (152 °C) of the biodiesel than the standard, indicating its high potential and ease of storage stability than standard biodiesel.
The fleshing waste from tannery was used to produce biodiesel by sustainable crude protease enzymatic hydrolysis process. The residue after fat extraction can be used for biofertilizer preparation with other wastes. This is an important sources of renewable energy generation which can valorized waste. The enzymatic process extracted extremely enhanced amount fat from the wastes which is about 34.9% of the dry weight of wastes. Display omitted
In the aftermath of the global financial crisis of 2007–2009, the Basel III based capital regulation has been emphasized to ensure financial stability. Critics, however, argue that stringent capital ...requirements may force banks to increase the cost of financial intermediation. In addition, banks may adjust capital ratios and portfolio risk upward simultaneously increasing the overall financial fragility. In this backdrop, we investigate the impact of capital regulation on the cost of financial intermediation and bank risk-taking behavior using a panel data-set of 32 Bangladeshi commercial banks over the period of 2000–2014. We find that bank capital adequacy ratios have a positive association with the cost of financial intermediation, whereas a negative association with bank risk-taking variables. Results remain same when we use equity to total assets ratio as an alternative measure of bank capital. We also observe that an increase in bank income diversification and management efficiency decreases the cost of financial intermediation. Surprisingly, the banking market structure and GDP growth have no measurable impact on the cost of financial intermediation and bank risk-taking behavior. Finally, we draw important implications for bank regulators in general, and for the Central Bank of Bangladesh in particular.
Chitosan-based nanoparticles have demonstrated a growing potential for use in the drug delivery systems due to their remarkable versatility. To enhance the effectiveness of chitosan-based ...nanoparticles for stimulus-responsive anticancer drug delivery, a novel pH-sensitive semi-interpenetrating networks (semi-IPN) of chitosan-poly(1-vinyl imidazole) (CS-PVIm) and Chitosan-poly(methacrylic-acid) (CS-PMAA) nanoparticles were synthesized through free radical polymerization. The semi-IPN nanoparticles were analyzed to evaluate their suitability as drug carrier. The SEM analysis revealed that the nanoparticles were spherical and within the nanoscale size range. The average particle size measured by DLS for CS-PMAA nanoparticles was 107.9 nm without the drug and 175.2 nm after the drug encapsulation. CS-PVIm-nanoparticles had an average size of 138.32 nm, which was increased to 165.84 nm after the drug loading. ATR-FTIR confirmed the formation of CS-PVIm and CS-PMAA nanoparticles. Cytotoxicity analysis showed that the nanoparticles are biocompatible, with over 95 % of cell survival for the HeLa cell lines. Further, Doxorubicin-hydrochloride (Dox) loaded nanoparticles exhibited sustained drug release caused by the protonation and deprotonation of their functional groups based on pH change. The CS-PVIm-nanoparticles showed encapsulation efficiency (EE) of 57 %, whereas EE of CS-PMAA-nanoparticles were 52 %, respectively. This research presents a straightforward method for producing intelligent pH-responsive semi-IPN-nanoparticles tailored for anticancer drug delivery.
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