We report the synthesis of two-dimensional (2D) Co3S4 in a nanothickness sheetlike morphology via simple hydrothermal process and its application to electrochemical energy-storage devices. The ...presence of unique mesopores with a combination of core/shell nanoparticles in the nanosheets showed superior electrochemical performances as a negative electrode for a Li-ion battery (LIB) and an electrocatalyst in Li–O2 battery applications. A high discharge capacity of ∼968 mAh g–1 is noted after 60 cycles with excellent cycling stability when evaluated as an anode for a LIB. On the other hand, the first discharge capacity of ∼5917 mAh g–1 is observed with a high reversibility of 95.72% for the Li–O2 battery point of view. This exceptional electrochemical performance in both applications is mainly attributed to the presence of mesoporous with core/shell 2D nanostructure, which translates more catalytic bifunctional (oxygen reduction reaction/oxygen evolution reaction) active sites for Li–O2 and sustains the volume variations that occur in a three-dimensional manner upon the charge–discharge process for LIB applications. Ex situ studies, such as transmission electron microscopy, X-ray photoelectron spectroscopy, and impedance spectroscopy studies, are also conducted to validate the reaction mechanisms.
Li-air batteries attract abundant attention in recent years with superior performance, and have largely replaced traditional methods of energy storage. The main objective of Li–air battery is to ...provide long-range electric-vehicles, while functioning as an environmentally friendly and compact energy storage solution. They offer the highest theoretical energy density (3500 Wh/kg), almost 20% higher than the ordinary Li-ion batteries. Nonetheless, Li-air batteries still face numerous issues, the most serious of which are high overpotential and parasitic reactions. Several redox mediators (RM) have been studied in order to reduce the high overpotential and the influence of side reactions. RM function in the electrolyte as soluble catalysts, limiting the formation of singlet oxygen while promoting the formation of discharge product Li2O2. This research primarily focuses on the optimization of Li-air cells with different redox mediators in conjunction with appropriate electrolyte, as a result reducing overpotential, parasitic byproducts and increasing efficiency. Under standard electrolytic conditions, ruthenocene exhibits high stability by completing 83 cycles, thus outperforming the other mediators being investigated. Further, di-tert-butyl-1,4-benzoquinone is more commonly used for discharge reaction and has been shown to increase the capacity of Li–O2 batteries by 80 times. This study reconfirms lithium bis(trifluoromethylsulfonyl) imide in tetraethyleneglycol dimethylether as the most stable electrolyte.
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•LABs offer high energy density but pose overpotential and parasitic reactions.•Redox mediators or soluble catalysts are studied to reduce overpotential issues.•Ruthenocene is highly stable and outperforms all other mediators.•DBBQ is commonly used for discharge and increases the capacity of LABs 80 times.
The graphene/cubic cobaltite oxide nanosheets (rGO/Co3O4) with a face centered cubic crystalline structure are synthesized and are exploited as effective cathode catalysts in high performance ...Lithium-air batteries. The morphological images enunciate that 220 nm average diameter of Co3O4 nanosheets are effectively anchored over the graphene sheets and the diameter of individual nanoparticles that construct the cubic nanosheets is 5 nm. The growth and composite formation mechanisms of prepared nanostructures are identified from Raman and FT-IR spectroscopic techniques. rGO/Co3O4 composite exhibits a lower voltage, high discharge capacity of 4150 mAh g−1 and displays superior cyclability without any capacity losses, signifying the excellent rechargeability of the fabricated electrodes. The post mortem analysis of electrodes specify the existence of lithium peroxide (Li2O2), lithium oxide (Li2O) and lithium carbonate (Li2CO3) discharge products, revealing the involved electrochemical reaction of Lithium-air batteries. The excellent electrochemical properties of rGO/Co3O4 composite is due to the combination of rapid electrokinetics of electron transport and high electrocatalytic activity toward oxygen reduction reaction given via the synergetic effects of rGO and cubic Co3O4 nanosheets. These findings provide fundamental knowledge on understanding the influence of morphological and structural properties of graphene based nanostructures toward Lithium-air battery performances.
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•Reduction of GO and insitu generation of Co3O4 nanosheets occurred concurrently.•Synergetic interaction between Co3O4 and rGO improved oxygen reduction rate.•Co3O4 centres involved reaction mechanism in Li-air battery is detailed.•rGO/Co3O4 exhibited a higher discharge capacity with an excellent cyclability.•The lithium based discharge products in electrodes are systematically analyzed.
Lipids extraction from wet and unbroken microalgae (Chlorella vulgaris) using subcritical water with aid of co-solvents has been investigated. Lipids extraction from wet and unbroken microalgae has a ...crucial role in order to eliminate dewatering and drying steps. Subcritical water is able to extract lipids from feedstock with high water content. This work was conducted to study several factors affecting in subcritical water extraction (SWE) from wet and unbroken microalgae. In this study, effect of co-solvent types (without co-solvent, chloroform, methanol, ethanol, ethyl acetate, and n-hexane) under subcritical water (microalgae = 5g (dry weight), moisture content= 94.12%, T= 160°C, P = 80 bar, t= 30 min), extraction time (15 min, 30 min, 1 h, 3 h, and 5 h), and temperature (160o C, 180o C and 200o C) on yield of lipids were investigated orderly. Yield of lipids obtained without co-solvent (water polarity index = 10.2) and with co-solvents of methanol (PI=5.1), ethanol (PI=5.2), chloroform (PI=4.1), ethyl acetate (PI=4.4), and n-hexane (PI=0.1) were 38.73%, 26.47%, 26.12%, 51.93%, 53.40%, and 25.59%, respectively compared to the yield of lipids extracted using Bligh and Dyer method. Ethyl acetate is solvent with moderate PI, therefore can extract more lipids that is also have moderate polarity. Ethyl acetate shows a good performance to extract lipids from wet and unbroken microalgae because ethyl acetate can extract broader range of lipids including neutral and polar lipids. This study also found that increasing of extraction time and temperature to extract lipids in subcritical water condition can increase yield of lipids.
In the current research work, Ni0.2Co2.8O4 and Ni0.2Co2.8/MWCNTs have been synthesized via facile sol-gel and wet impregnation method. The synthesized materials attained the crystalline structures as ...evident from X-ray diffraction analysis (XRD). The uniform morphology and well dispersion of Ni0.2Co2.8O4 onto MWCNTs was observed via scanning electron microscopy (SEM). The electrochemical investigations for supercapacitor application by cyclic voltammetry (CV), galvanostatic charge discharge (GCD), and electrochemical impedance spectroscopy (EIS) revealed that, among both materials, Ni0.2Co2.8O4/MWCNTs has high specific capacitance (CV; 505.8 Fg-1 at 5 mV/s, GCD; 1598 Fg-1 at 0.5 A/g), greater capacitance retention (85 %) at 1000 cycles and has lower charge transfer resistance (Rct; 3.48 Ω cm2). These findings reflected the potential candidacy of Ni0.2Co2.8O4/MWCNTs to be used as anode material in supercapacitor. Further investigations by CV and linear sweep voltammetry (LSV) for oxygen evolution reaction (OER) activity in 1.0 M KOH showed comparatively low over potential of 340 mV @100 mA/cm2 for the same integrated material. Additionally, the lower Tafel slope (47 mV/dec) and solution resistance authenticated it as an appropriate electrocatalyst for OER in water splitting. The CPE (controlled potential electrolysis) revealed the stability of both materials for OER in water oxidation.
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•Ni0.2Co2.8O4 and integrated Ni0.2Co2.8O4/MWCNTs anode materials.•Synthesis via facile sol-gel and wet impregnation method.•Morphological, and structural characterizations.•Materials' electrochemical performance for super capacitor and OER.•Better anode candidacy of integrated Ni0.2Co2.8O4/MWCNTs for both applications.
To study clinical manifestations and outcome of hyponatremia and hypernatremia in children with diarrhea.
We compared children aged 0-59 months hospitalized from 1 January to 31 December 2013 with ...hyponatremia (serum sodium <130 mmol/l), hypernatremia (serum sodium >150 mmol/l) and normonatremia (serum sodium 135-145 mmol/l).
The case fatality was significantly higher among the children with hypernatremia and hyponatremia than normonatremia. A logistic regression analysis adjusting for potential confounders revealed that children with hyponatremia are more likely to have convulsions, have severe acute malnutrition and be of older age compared with children with normal serum sodium. Children with hypernatremia are more likely to have convulsions and dehydration than normonatremic children (for all p < 0.05).
Early diagnosis and prompt management of hypo- and hypernatremia by identifying simple clinical predicting factors of these two conditions in diarrheal children <5 years of age is critically important to prevent deaths in such children, especially in resource-limited settings.
Reverse electrowetting-on-dielectric (REWOD) is a novel energy harvesting technique that has been gaining considerable amount of attention owing to its high power output even with the small amount of ...disturbance. To enhance the output power of REWOD, the dielectric layers in the system require a high capacitance. Nevertheless, current leakage is inevitable in such high-k dielectric materials. In this work, the application of a high-k dielectric material TiO2 has been investigated along with a new leakage barrier layer Al2O3 that acts as a lamination, in order to minimize the current leakage and maximize the power output. As expected, the laminated structure with TiO2 and Al2O3 exhibited reduced current leakage and relatively high capacitance compared to the single layer of TiO2 or Al2O3, respectively. As the electrical energy is generated through the interaction of liquid droplets and the multilayered dielectric film, the energy-harvesting performance displayed different behavior about current generation with respect to the top surface material that is in contact with the conductive droplet. Overall, the laminated REWOD energy harvesting system produced an enhanced power density of 15.36 mW cm−2 at a low bias voltage.
We investigate the nonlinear dynamics of a DNA molecule system by using the Peyrard-Bishop model. The PB model brings out the charge transport in DNA with the influence of twisting and we detect the ...regions of instability through the linear stability analysis. There are two regimes where the modulated charge patterns can occur under twisted and also the over twisted conformations. Numerical simulations confirm our analytical predictions. We conclude that, when the DNA molecule is over twisted and in the absence of twisting, the system may lead to the breaking of the hydrogen bond between base pairs.
PKM2 (Pyruvate kinase M2) is the isoform of pyruvate kinase which is known to catalyse the last step of glycolysis that is responsible for energy production. This specific isoform is known to be ...highly expressed in certain cancerous conditions. Considering the role of this protein in various cancer conditions, we used PKM2 as a target protein to identify the potential compounds against this target. In this study, we have examined 96 compounds of Zanthoxylum armatum using an array of computational and in silico tools. The compounds were assessed for toxicity then their anticancer potential was predicted. The virtual screening was done with molecular docking followed by a detailed examination using molecular dynamics simulation. The majority of the compounds showed a higher probability of being antineoplastic. Based on toxicity, predicted anticancer potential, binding affinity, and binding site, three compounds (nevadensin, asarinin, and kaempferol) were selected as hit compounds. The binding energy of these compounds with PKM2 ranged from −7.7 to −8.3 kcal/mol and all hit compounds interact at the active site of the protein. The selected hit compounds formed a stable complex with PKM2 when simulated under physiological conditions. The dynamic analysis showed that these compounds remained attached to the active site till the completion of molecular simulation. MM-PBSA analysis showed that nevadensin exhibited a higher affinity towards PKM2 compared to asarinin and kaempferol. These compounds need to be assessed properties in vivo and in vitro to validate their efficacy.
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•Selection of lead anti-cancer phytocompounds.•Phytocompounds as Potential Inhibitor of Pyruvate Kinase M2 (PKM2).•Protein-protein interactions must be inhibited to prevent tumor cells.•Majority of compounds showed a higher probability of antineoplastic properties.
The choice of electrolyte solvent is expected to play a key role in influencing the lithium-oxygen battery performance. The electrochemical performances of three electrolytes composed of lithium bis ...(trifluoromethane sulfonyl) imide (LiTFSI) salt and different solvents namely, ethylene carbonate/propylene carbonate (EC/PC), tetra ethylene glycol dimethyl ether (TEGDME) and dimethyl sulfoxide (DMSO) are investigated by assembling lithium oxygen cells. The electrolyte composition significantly varied the specific capacity of the battery. The choice of electrolyte also influences the overpotential, cycle life, and rechargeability of the battery. Electrochemical impedance spectra, cyclic voltammetry, and chronoamperometry were utilized to determine the reversible reactions associated with the air cathode.
•The choice of electrolyte solvent influences the lithium/O2 battery performance.•Three solvents; TEGDME, ECPC and DMSO exhibit proper reversible reaction.•TEGDME demonstrate a comparatively suitable electrode – electrolyte combination.
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