Effect of bication (Cu-Cr) substitution on the structure and electrochemical performance of LiMn2O4 spinel cathodes at low and high current rates

This report describes the detailed structural and electrochemical characterization of a series of low content (0.01 to 0.05) Cu-Cr bi-metal doped LiMn₂O₄ cathode material synthesized by sol–gel method. The structural and morphological features were described using XRD, SEM, TEM, EDAX and FTIR techniques. The electron transfer and its feasibility were discussed through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The charge–discharge studies were performed to evaluate the capacity fading and rate capability. It was found that the electrochemical performance is very much dependent on the amount of Cu-Cr bi-metal doping and interestingly decreased the capacity fading with high cycleability. The sample with the least amount of dopants (i.e., LiCu_0.01Cr_0.01Mn_1.98O₄) demonstrated much improved capacity, cycleability and high rate capability. The LiCu_0.01Cr_0.01Mn_1.98O₄ cathode exhibited a discharge capacity of 112 mA h g^?1 at very first cycle and retained 93 mA h g^?1 after 100 cycles at a C rate of 0.3. Further, the same material at very high current density (5 C) retained 83% of the initial discharge capacity. The Cu-Cr doping stabilized the spinel structure by suppressing the Jahn-Teller distortion effect and Mn dissolution and the resultant material showed the workability of the cathodes for devices which work at substantially high C-rate of 5C.     

Exploration of genetic diversity among medicinally important genus Epimedium species based on genomic and EST-SSR marker

Epimedium species has gained prime importance due to their medicinal and economic values. Therefore, in this study, 26 genomic SSR and 10 EST-SSR markers were developed for 13 medicinal species of the Epimedium genus and one out-group species Vancouveria hexandra W. J. Hooker to explore the existing genetic diversity. A total of 100 alleles by genomic SSR and 65 by EST-SSR were detected. The genomic SSR markers were presented between 2–7 alleles per locus. The observed heterozygosity (H_o) and expected heterozygosity (H_e) ranged from 0.00 to 4.5 and 0.0254 to 2.8108, respectively. Similarly, for EST-SSR, these values were ranged from 3.00 to 4.00 and 1.9650 to 2.7142. The number of alleles for EST-SSR markers ranged from 3 to 10 with an average of 3.51 per loci. It has been concluded that medicinally important species of the genus Epimedium possesses lower intraspecific genetic variation.     

Development of a Core–Shell Heterojunction TiO2/SrTiO3 Electrolyte with Improved Ionic Conductivity

Lately, semiconductor-membrane fuel cells (SMFCs) have attained significant interest and great attention due to the deliverance of high performance at low operational temperatures, <550 °C. This work has synthesized the nanocomposite core-shell heterostructure (TiO₂−SrTiO₃) electrolyte powder by employing the simple hydrothermal method for the SMFC. The SrTiO₃ was grown in situ on the surface of TiO₂ to form a core-shell structure. A heterojunction mechanism based on the energy band structure is proposed to explain the ion transport pathway and promoted protonic conductivity. The core-shell heterostructure (TiO₂−SrTiO₃) was utilized as an electrolyte to reach the peak power density of 951 mW cm⁻² with an open-circuit voltage of 1.075 V at 550 °C. The formation of core-shell heterostructure among TiO₂ and SrTiO₃ causes redistribution of charges and establishes a depletion region at the interface, which confined the protons′ transport on the surface layer with accelerated ion transport and lower activation energy. The current work reveals novel insights to understand enhanced proton transport and unique methodology to develop low-temperature ceramic fuel cells with high performance.     

Immobilization of ligands with precise control of density to electroactive surfaces

We report a broadly applicable surface chemistry methodology to immobilize ligands, proteins, and cells to an electroactive substrate with precise control of ligand density. This strategy is based on the coupling of soluble aminooxy terminated ligands with an electroactive quinone terminated monolayer. The surface chemistry product oxime is also redox active but at a different potential and therefore allows for real-time monitoring of the immobilization reaction. Only the quinone form of the immobilized redox pair is reactive with soluble aminooxy groups, which allows for the determination of the yield of reaction, the ability to immobilize multiple ligands at controlled densities, and the in-situ modulation of ligand activity. We demonstrate this methodology by using cyclic voltammetry to characterize the kinetics of a model interfacial reaction with aminooxy acetic acid. We also demonstrate the synthetic flexibility and utility of this method for biospecific interactions by installing aminooxy terminated FLAG peptides and characterizing their binding to soluble anti-FLAG with surface plasmon resonance spectroscopy. We further show this methodology is compatible with microarray technology by printing rhodamine-oxyamine in various size spots and characterizing the yield within the spots by cyclic voltammetry. We also show this methodology is compatible with cell culture conditions and fluorescent microscopy technology for cell biological studies. Arraying RGD-oxyamine peptides on these substrates allows for bio-specific adhesion of Swiss 3T3 Fibroblasts.     

Two-dimensional fin with convective base condition

When solving a two-dimensional model of an isolated fin, researchers have mainly concentrated on either a constant or a periodic fin base temperature. It is possible to obtain a numerical solution by a convective boundary condition on the fin base. However, in an analytical solution, one cannot calculate an arbitrary constant because of the convective boundary condition of the separation of variables. Therefore a heat balance is applied here to resolve this difficulty. In addition, a modified solution is presented which does not involve any additional mathematics with respect to the classical approach of solving a one-dimensional model. For different values of the Biot number $B_{22}$, a comparison of one- and two-dimensional solutions is given. Relative errors of the heat flow rates predicted by the classical and modified one-dimensional solutions, and the respective exact two-dimensional solution with respect to an, are computed. It is found that, for large values of $B_{22}$ (say 50.0) modified solution, by using a convective condition at the fin base gives significant accuracy improvements in comparison to the classical one-dimensional technique.     

Potentiometric studies on mixed-ligand complexes of cobalt(II) and nickel(II) with amino acids as primary ligands and imidazole as secondary ligand

Summary The formation constants of mixed-ligand complexes of cobalt(II) and nickel(II) with glycine, DL--alanine and DL-valine as primary ligands and imidazole as secondary ligand have been determined potentiometrically under physiological-like conditions (T=37°C and I=0.15 M KNO₃). The proton association constants of the free ligands and the stability constants for binary systems involving the amino acids and imidazole were also determined under identical conditions, and the experimental pH-titration data were analysed using the computer SUPERQUAD program. The relative stability of the ternary complex as compared to that of the corresponding binary complexes has been quantitatively expressed in terms of log K and log X values.     

Potentiometric studies on mixed-ligand complexes of copper(II) and zinc(II) with some amino acids (glycine,DL-α-alanine and DL-valine) as primary ligands and imidazole as a secondary ligand

Summary Mixed-ligand complexes of Cu^II and Zn^II with glycine(GL), DL--alanine (AL) and DL-valine (VL) as primary ligands and imidazole (IM) as secondary ligand have been studied potentiometrically under physiological conditions (t=37° C and I=0.15 M KNO₃). The experimental pH-titration data were analysed with aid of the SUPERQUAD computer program in order to evaluate formation constants of binary and ternary systems involying amino acids (AA) and IM. The relative stability of each of the ternary complexes was compared with that of corresponding binary complexes in terms of log K and log X values.