Sharif Digital Repository

The ion exchange process is a promising method for lithium extraction from brine and seawater having low concentrations of this element. To achieve this goal, it is vital to use an effective adsorbent with maximum lithium adsorption potential together with a stable structure during extraction and insertion of the ions. In this study, titanium dioxide and then lithium titanate spinel with nanotube morphology was synthesized via a simple two-step hydrothermal process. The produced Li4Ti5O12 spinel ternary oxide nanotube with about 70 nm diameter was then treated with dilute acidic solution in order to prepare an adsorbent suitable for lithium adsorption from local brine. Morphological and... 

The nature of alumazine⋯M (M = Li+, Na+, K+, Be2+, Mg2+, AND Ca2+) interactions was studied by ab initio calculations. The interaction energies were calculated at MP2/6-311++G(d,p)//B3LYP/6-311++G(d,p) level. The calculations suggest that the size and charge of cation are two important factors that affect the interaction energy, charge transfer values and the variation in aromaticity of alumazine ring upon complexation. The theory of atoms in molecules (AIM) and natural bond orbital (NBO) analyses of complexes indicate that the variation of densities and the extent of charge shifts upon complexation correlate well with the obtained interaction energies. Finally, nucleus independent chemical... 

Gas-phase acidities of nucleosides, combined with the knowledge of deprotonation sites, could improve our understanding of chemical reactions to biological systems. In this paper, we mainly focus our attention on the influence of cation coordination on acidities of multiple sites in cytosine nucleosides. The acidities of multiple sites in M +-L (where L represents cytosine nucleosides and M + is an alkali metal ion, including Li +, Na + and K +) complexes have been investigated theoretically, employing B3LY P6-311++G(d,p) basis sets. The geometrical characters, gas-phase acidities, sugar puckering and electronic properties of non-deprotonated and/or deprotonated complexes have been... 

In this study, copper oxide nano particles were synthesized by batchwise supercritical hydrothermal method. After preparation of CuO nano particles, they were immobilized into the porous matrix of sodium alginate. The drying process formed a very porous structure that is useful for enhancing of adsorption activity. Produced CuO particles were characterized by X-ray diffractometery (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and BET for measuring the surface area. The prepared materials were then used as adsorbent in the removal of toxic metal ions in aqueous solution. To optimize the adsorption system, the effect of various parameters such as adsorbent... 

The geometries of the complexes of Be 2+, Mg 2+, and Ca 2+ metal cations with borazine ring were studied. The complexes were optimized at the B3LYP level and the 6-311++G(d,p) basis set. Then, the interaction energies corrected by basis set super position error were calculated in the same level. The results show that interaction energy is strongly dependent on the charge-to-size ratio of the cation. Therefore, Be 2+ cation has the most interaction energy value with respect to Mg 2+ and Ca 2+ metal cations. Natural bond orbital analysis was performed to calculate the charge transfer and natural population analysis of the complexes. Quantum theory of atoms in molecules was also applied to... 

In this paper, we explore theoretically energetic and structural properties of the possible cations formed via hydride ion abstraction at various sites of sugar part of cytosine nucleosides by employing B3LYP exchange-correlation functional with 6-311++G (d,p) orbital basis sets. In general, the hydride ion abstracted sugar cations of cytosine nucleosides have the following stability sequence: caH2′ > caH1′ > caH3′ > caH4′ > caH5′ for cytidine and caH1′ > caH4′ > caH3′ > caH5′ > caH2′ for deoxycytidine. Furthermore, the effect of solvent environment on the stability order of cations integral equation formalism of the polarized model (IEF-PCM) was employed to model aqueous solution. The... 

The ion exchange process is a promising method for lithium extraction from brine and seawater having low concentrations of this element. To achieve this goal, it is vital to use an effective adsorbent with maximum lithium adsorption potential together with a stable structure during extraction and insertion of the ions. In this study, titanium dioxide and then lithium titanate spinel with nanotube morphology was synthesized via a simple two-step hydrothermal process. The produced Li4Ti5O12 spinel ternary oxide nanotube with about 70 nm diameter was then treated with dilute acidic solution in order to prepare an adsorbent suitable for lithium adsorption from local brine. Morphological and... 

In this article, we use an efficient analytical method called homotopy analysis method (HAM) to derive an approximate solution of nonlinear ion sound waves equation. Actually, we solved Korteweg-de Vries equation arises in a one-dimensional macroscopic plasma model describing the weakly nonlinear evolution of ion sound speed by the HAM. Unlike the perturbation method, the HAM does not require the addition of a small physically parameter to the differential equation. It is applica-ble to strongly and weakly nonlinear problems. Moreover, the HAM involves an auxiliary parameter, which renders the convergence param-eter of series solutions controllable, and increases the convergence, and... 

Uranium (VI) sorption using an anionic exchanger resin, namely Amberlite IRA910, in the presence of sulfate anions was the subject of current study. Batch sorption experiments were carried out to evaluate the influence of operational parameters such as pH, contact time, initial concentration and existence of various anions (including phosphate, sulfate, chloride, fluoride, and nitrate) in the solution on Amberlite IRA910 sorption behavior. Experiments revealed that uranium adsorption was fulfiled at pH>3 and 50 min to amount of 80%. Kinetics study revealed that the pseudo-second-order model showed better curve-fitting regression of the experimental data than the pseudo-first-order one.... 

Polyols were used as model ligands for Mg2+, Ca2+, and Zn2+ complexes to study the role of the hydrogen bond network on the metal binding affinity and modulation of successive pKa values using density functional theory. The results confirm that the acidity of polyols dramatically increases upon metal complexation in the order Zn2+ > Mg2+ > Ca2+. For example, the three H-site positions in the hydroxyl groups of the heptaol, bound to Zn2+, are 11.2, 29.9, and 30.9 pKa units (in methanol) more acidic than those of pure heptaol. This acidity enhancement leads to making polyols as good ligands toward complexation. For instance, the formation constants of the heptaol in the presence of Zn2+, Mg2+,... 

Inverted perovskite solar cells (PSCs) have been introduced as better candidate for roll-to-roll printing and scale-up than their conventional configuration counterparts, while their fabrication is technically more demanding. The common light absorbing layer in inverted PSCs is the single cation methylammonium lead iodide (MAPbI3) perovskite, whereas mixed-ion perovskites are chemically more stable. In mixed-ion perovskites, where FA (formamidinium) is the main replacement for MA, the electron affinity is larger than in MAPbI3 perovskites, leading to possible barriers against photoelectron collection by the electron transporting layer (ETL). In this paper we report on a mixed-ion... 

Today, Li-ion batteries (LIBs) are the most common rechargeable batteries used in electronic devices. SnO2 with theoretical specific capacity of 782 mAh/g is among the best anode materials for LIBs. In this report, Threedimensional SnO2 nanowires (NWs) on carbon nanotube (CNT) thin film (SnO2 / CNT) is fabricated using a combination of vacuum filtration and thermal evaporation techniques. The resulting 3D heterostructure SnO2/CNT was characterized by X-ray diffraction, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). This fabricated SnO2/CNT electrode has been tested as a flexible and binderfree anode for LIB, which exhibits high initial discharge/charge... 

In this paper we introduce a Simplified Single Particle Model (SSPM), which is obtained from the general mathematical formulation of Li-ion batteries. The model is validated by using different commercial graphite/LiFePO4 cells, and results show agreement with more complicated models and experimental data for low operating currents of less than 1C. A maximum relative error of less than 2% can be observed to estimate cell voltage in the plateau region of the charge/discharge curves. Therefore, the proposed model is suitable in the case of stand-alone renewable energy systems, where battery current is typically lower than C/10. By increasing the current, the SSPM deviates from more accurate... 

The coordination geometries, electronic features, absolute metal ion affinities, geometrical multiplicity and binding strength for the complexes formed by Mg2+, Ca2+, Zn2+ and Cu+ with cytidine and deoxycytidine have been determined theoretically employing the hybrid B3LYP exchange-correlation functional and using 6-311++G(d,p) orbital basis sets. Our study shows that the most stable coordination modes of cytosine nucleosides with these cations are rather similar. In the isolated state, the most stable form corresponds to a tridentate complex in which the cation interacts with three oxygen atoms: one from the carbonyl oxygen of cytosine moiety and two from the sugar unit (i.e., O5′ and O4′).... 

The main process in lithium-ion batteries is insertion/extraction of lithium into/from active electrode particles. Some active material of lithium-ion battery electrodes experiences a large volume change due to changes in lithium concentration. Since the failure of the electrode might be caused by large stresses, the mechanical phenomena in the electrode which are associated with the insertion and extraction of lithium, are of particular importance. This paper establishes an integrated framework of balance laws and thermodynamically consistent equations which couples lithium diffusion with a small elastic deformation. We investigate the effect of hydrostatic stress on lithium diffusion and... 

Xanthene dyes, such as fluorescein and rhodamine, have played crucial rules in biological sciences especially covalent attachment of these organic compounds to biomolecules. 3-O-methylfluorescein and 3,6-O-dimethylfluorescein were synthesized and purified using a facile procedure. 3,6-O-dimethylfluorescein, which lacks fluorescence, was treated with sodium hydroxide and sulfuric acid solutions, giving rise to yellow and green fluorescent compounds, respectively. In both basic and acidic conditions, donor-acceptor structures were formed. The reaction of 3,6-O-dimethylfluorescein with acids, in a reversible manner, emitted green fluorescence, whereas its reaction with hydroxide ion,... 

In Li-ion batteries, application of active materials can enhance the kinetics of the charge-discharge process, reduce the costs and improve the safety of the system. In this work, the effect of nickel content and lithium excess in Li1+x (Ni0.4-xMn0.5Co0.1) O2 compounds on the electrochemical performance of the lithium-ion battery cathode have been studies. For this purpose, three compounds of NMC in the stoichiometric state were synthesized via co-precipitation as the cathode active material. XRF and EDS analyses indicate that precursors and oxide compounds are well synthesized. The final compound of synthesized cathodes was obtained by ICP analysis. XRD results also suggest that the... 

Development of visual detection methods regarding water pollutants can effectively facilitate water resource monitoring programs. A wide color-varying ratiometric approach has been developed for sensitive determination of sulfide by mixing orange emissive glutathione stabilized gold nanoclusters (AuNCs) and blue emissive urea stabilized carbon dots (CDs) in an appropriate ratio. Under a single excitation wavelength of 365 nm, the ratiometric fluorescence (RF) probe exhibited two distinct emission bands at 452 and 607 nm corresponding to CDs and AuNCs, respectively. Owing to the high affinity of sulfide ions to AuNCs in alkaline medium, the fluorescence (FL) of AuNCs was turned-off while the...