Generalization of five q-series identities of Ramanujan and unexplored weighted partition identities

The Ramanujan Journal - Ramanujan recorded five interesting q-series identities in a section that is not as systematically arranged as the other chapters of his second notebook. These five...     

Ternary-material lithium-ion battery SOC estimation under various ambient temperature

Ambient temperature produces great effects on battery state-of-charge (SOC) estimation, due to the unstable estimation algorithm, the weakened traceability of battery model, and variable model parameters at various temperatures, especially lower temperatures. The widely used method based on the equivalent circuit model (ECM) offline in using different algorithm, like current integral, the extended Kalman filter (EKF), or the unscented Kalman filter (UKF), can obtain an accurate SOC estimation at room temperature, but it is difficult to guarantee the high precision at lower temperatures. To address this problem, the battery model is investigated at different temperature, and an offset item is proposed to develop the observer equation in the estimated model. Then, the square root of the Sigma points Kalman filter (SR-UKF) is applied, and on the basis of the individual model parameter-temperature table and the developed model, the high accuracy of SOC estimation is achieved. Additionally, considering the burden of original parameter modification (all model parameters modified) at various temperature which will increase the product cost and computational complexity of the battery management system (BMS), the relationship between individual model parameter and the error of SOC estimation is built, which is helpful for the simplification of parameter modification. The results indicate that the proposed method based on the developed estimated model and the simplified parameter modification can achieve an accurate, stable, and efficient SOC estimation.     

Revisiting the ‘cis-effect’ in 1,2-difluoro derivatives of ethylene and diazene using ab initio multireference methods

The relative stabilities of cis- and trans- isomers of 1,2-difluoroethylene and 1,2-difluorodiazene have been studied via the state-specific multireference coupled cluster (SS-MRCC) method and its perturbative counterpart through the computation of the optimised structures and corresponding energies. Despite the existence of several cis-destabilising mechanisms, present calculations reveal the energetic preference of the cis- isomer (the cis-effect) for the systems considered here. Differences in structural parameters and vibrational frequencies among cis- and trans- isomers have been discussed. Very good agreement of our estimates has been found with the benchmark theoretical and experimental results. The SS-MRCC methods produce a smooth and consistent behaviour across the entire torsional surface for the cis–trans isomerisation indicating that the method has sufficient flexibility to model large changes in electronic structure that accompany chemical changes.     

Palladium(II)‐Catalyzed meta‐C?H Olefination: Constructing Multisubstituted Arenes through Homo‐Diolefination and Sequential Hetero‐Diolefination

Divinylbenzene derivatives represent an important class of molecular building blocks in organic chemistry and materials science. Reported herein is the palladium‐catalyzed synthesis of divinylbenzenes by meta‐C H olefination of sulfone‐based arenes. Successful sequential olefinations in a position‐selective manner provided a novel route for the synthesis of hetero‐dialkenylated products, which are difficult to access using conventional methods. Additionally, 1,3,5‐trialkenylated compounds can be generated upon successful removal of the directing group.     

Supercontinuum generation in ultra-flat near zero dispersion PCF with selective liquid infiltration

We present a new design study of ultra-flat near zero dispersion PCF with selectively liquid infiltration with all uniform air-holes in the cladding. The dependence of the individual parameters upon dispersion has been presented in detail. The study establishes that varying Λ influences the total dispersion, whereas d has the desired effect of modifying the dispersion slope, and varying n_L modifies both. With the above study we could achieve near zero ultra-flat dispersion as small as 0 ± 0.41 ps/nm/km for broad wavelength range of 452 nm. The optimized near zero ultra-flat dispersion PCF has been targeted for smooth and flat broadband spectrum supercontinuum generation (SCG) for near Infrared (IR) applications. Broadband SC generations corresponding to three different designs of ultra-flat dispersion fiber have been carried out by using picoseconds pulse laser around the first zero dispersion wavelengths (ZDW). The numerical results show that FWHM of around 400 nm with less than a meter long fiber can be achieved with these fibers that cover most of the communication wavelength bands. The proposed design study will be applicable for applications in the field of tomography, Dense Wavelength Division Multiplexing (DWDM) system, spectroscopy, etc.     

Enhancement of uranyl fluorescence using trimesic acid: Ligand sensitization and co-fluorescence

Trimesic acid (TMA) was shown to sensitize and enhance uranyl fluorescence in aqueous medium, with the enhancement being a maximum at pH 5.0. Fluorescence spectra and lifetime data together suggest that TMA complexes with uranyl . The fluorescence of UO₂2+ in its acid complex is further enhanced by more than two orders of magnitude following the addition of Y³⁺; a process referred to as co-fluorescence, leading to the possibility of detecting uranium at sub ng/mL level. The present study demonstrates, for the first time, fluorescence enhancement of the uranyl species due to co-fluorescence.     

An alternative optical method of determining the unknown microwave frequency by the use of electro-optic materials and semiconductor optical amplifier

There are found different established methods for measuring the frequency of an unknown microwave signal. Several resonating and electronic methods are found where the frequency of a microwave is measured with good performances, where each method has its own advantage. Here in this communication the authors propose a new concept of measuring the frequency of unknown microwave with the joint uses of reflecting semiconductor optical amplifier (RSOA) and electro-optic Pockel cell. To measure the frequency a known microwave source of variable and calibrated frequency is also required. Then with the help of a RSOA and electro-optic material one can find the unknown microwave frequency more accurately than that of any conventional mechanism. This method can extend a high degree of accuracy as optics is used to measure the unknown microwave frequency. As optical signal has million time greater frequency than that of microwave signal therefore a high degree of accuracy of frequency measurement is achieved. The electro-optic material takes the role of phase modulation for splitting an optical wave into several frequencies.     

Nickel(II)‐Mediated Reversible Thiolate/Disulfide Conversion as a Mimic for a Key Step of the Catalytic Cycle of Methyl‐Coenzyme M Reductase

According to the well‐accepted mechanism, methyl‐coenzyme M reductase (MCR) involves Ni‐mediated thiolate‐to‐disulfide conversion that sustains its catalytic cycle of methane formation in the energy saving pathways of methanotrophic microbes. Model complexes that illustrate Ni‐ion mediated reversible thiolate/disulfide transformation are unknown. In this paper we report the synthesis, crystal structure, spectroscopic properties and redox interconversions of a set of Ni^II complexes comprising a tridentate N₂S donor thiol and its analogous N₄S₂ donor disulfide ligands. These complexes demonstrate reversible Ni^II‐thiolate/Ni^II‐disulfide (both bound and unbound disulfide‐S to Ni^II) transformations via thiyl and disulfide monoradical anions that resemble a primary step of MCR's catalytic cycle.