Electrocatalytic Reduction of Nitrogen to Ammonia Using Tiara-like Phenylethanethiolated Nickel Cluster

The fixing of N₂ to NH₃ is challenging due to the inertness of the N≡N bond. Commercially, ammonia production depends on the energy-consuming Haber-Bosch (H−B) process, which emits CO₂ while using fossil fuels as the sources of hydrogen and energy. An alternative method for NH₃ production is the electrochemical nitrogen reduction reaction (NRR) process as it is powered by renewable energy sources. Here, we report a tiara-like nickel-thiolate cluster, [Ni₆(PET)₁₂] (where, PET=2-phenylethanethiol)] as an efficient electro-catalyst for the electrochemical NRR at ambient conditions. Ammonia (NH₃: 16.2±0.8 μg h⁻¹ cm⁻²) was the only nitrogenous product over the potential of −2.3 V vs. F_c⁺/F_c with a Faradaic efficiency of 25%±1.7. Based on theoretical calculations, NRR by [Ni₆(PET)₁₂] proceeds through both the distal and alternating pathways with an onset potential of −1.84 V vs. RHE (i.e., −2.46 V vs. F_c⁺/F_c) which corroborates with the experimental findings.     

Calculations find that tunneling plays a major role in the reductive elimination of methane from hydridomethylbis(trimethylphosphine)platinum: how to confirm this computational prediction experimentally

DFT calculations, including the effects of small curvature tunneling, have been performed on the reductive elimination of methane from hydridomethylbis(trimethylphosphine)platinum (1d). The calculations find that at 250 K tunneling results in an increase in the rate constant for reductive elimination by a factor of 4, a lowering of Ea by 1.7 kcal/mol, and a decrease in A by a factor of nearly 10. Tunneling is also calculated to increase the primary H/D kinetic isotope effect (KIE) from k(1d)/k(1f) = 2.26 to k(1d)/k(1f) = 4.12 and to result in a large secondary KIE of k(1d)/k(1e) = 1.35. In addition, tunneling is predicted to result in a violation of the rule of the geometric mean, so that the secondary KIE for reductive elimination of methane-d1 from 1f is calculated to be k(1f)/k(1g) = 1.06, which is much smaller than the secondary KIE of k(1d)/k(1e) = 1.35 for reductive elimination of methane from 1d. Comparison of the measured values of k(1d)/k(1e) and k(1f)/k(1g) is therefore proposed as an experimental test of the prediction that tunneling plays an important role in the reductive elimination of methane from 1d.     

Multi-Party Quantum Private Comparison Protocol with an Almost-Dishonest Third Party using GHZ States

This article proposes an innovative quantum private comparison (QPC) protocol for n users using GHZ states, where an almost-dishonest third party (TP) is introduced to assist the participants for comparing their secrets. It is argued that as compared to the existing QPC protocols our proposed scheme has some considerable advantages. First, in the existing QPC protocols, the TP can only to determine whether all participants’ secrets are equal or not. Instead of that, in our proposed scheme a TP can even compare the secrets between any subsects of users. Second, since our proposed scheme is based on GHZ state; hence it can ensure higher efficiency as compared to other existing multi-party QPC protocols on d-dimension photons.     

Electron and hole mobilities in polymorphs of benzene and naphthalene: role of intermolecular interactions

The hole and electron mobilities of the polymorphs of benzene and naphthalene crystals are estimated through quantum chemical calculations. The reorganization energy (lambda) and the charge-transfer matrix elements (Hmn) calculated for the two molecules reveal that these crystals can be used for dual applications, for both hole and electron conductance. The electron mobilities are five to eight times more than the hole mobilities for benzene while for naphthalene, the hole mobilities are almost an order magnitude more than the electron mobilities. The transfer matrices for both hole and electron conductance decrease monotonically with increase in the intermolecular distances. Calculations for various unique stacked dimers as determined from the radial distribution functions in both the crystals for the two molecules show strong dependence on the orientations of the rings and for similar intermolecular separations; Hmnhole is larger than Hmnelectron. The crystal mobilities are calculated from the weighted average over all the unique pair of molecules. The overall preference in a crystal for hole or electron mobility depends on the mutual competition of lambdahole/lambdaelectron and Hmnhole/Hmnelectron. From our microscopic understanding of essential parameters, specific dimers are identified from the crystalline solids of the two polymorphs and experimental strategies are suggested to enrich such pairs in aggregates for enhancing mobilities for these organic solids.     

Chaos in the delay logistic equation with discontinuous delays

This paper analyzes a delay logistic equation which models a feedback control problem. Interval map associated to the system is derived. By calculating Lyapunov exponent, we indicate stable orbit and chaotic phenomenon respectively. The results are verified through computer simulation. We identify the parameter which controls the dynamics.     

Relativistic compact stars with charged anisotropic matter

In this article, we perform a detailed theoretical analysis of new exact solutions with anisotropic fluid distribution of matter for compact objects subject to hydrostatic equilibrium. We present a family solution to the Einstein-Maxwell equations describing a spherically symmetric, static distribution of a fluid with pressure anisotropy. We implement an embedding class one condition to obtain a relation between the metric functions. We generalize the properties of a spherical star with hydrostatic equilibrium using the generalised Tolman-Oppenheimer-Volkoff (TOV) equation. We match the interior solution to an exterior Reissner-Nordström one, and study the energy conditions, speed of sound, and mass-radius relation of the star. We also show that the obtained solutions are compatible with observational data for the compact object Her X-1. Regarding our results, the physical behaviour of the present model may serve for the modeling of ultra compact objects.     

Noncommutative Wormholes in f(R) Gravity with Lorentzian Distribution

In this paper, we derive some new exact solutions of static wormholes in f(R) gravity supported by the matter possesses Lorentzian density distribution of a particle-like gravitational source. We derive the wormhole’s solutions in two possible schemes for a given Lorentzian distribution: assuming an astrophysically viable F(R) function such as a power-law form and discuss several solutions corresponding to different values of the exponent (here $F =\frac{df}{dR}$ ). In the second scheme, we consider particular form of two shape functions and have reconstructed f(R) in both cases. We have discussed all the solutions with graphical point of view.     

Effect of External Electric Field on H‐Bonding and π‐Stacking Interactions in Guanine Aggregates

The structure and electronic properties of guanine oligomers and π stacks of guanine quartets (G‐quartets) with circulene are investigated under an external field through first‐principles calculations. An electric field induces nonplanarity in the guanine aggregates and also leads to an increase in the H‐bond distances. The calculations reveal that the binding energy of the circulenes with G‐quartets increases on application of an electric field along the stacking direction. The HOMO–LUMO gap decreases substantially under the influence of an external field. The contribution of a simple dipole–dipole interaction to the stability of the stacked system is also analyzed. The electric field along the perpendicular axis increases the dipole moments of the guanine dimer, trimer, and quartet. Such an increase in the dipole moment facilitates stacking with circulenes. The stability of G‐quartet–circulene π stacks depends on the phase of the dipole moment (in‐phase or out‐of‐phase) induced by an external electric field. The stability of stacks of bowl‐shaped circulenes with G‐quartets depends on the direction of the applied field.     

Miniature Non-thermal Plasma Induced Cell Cycle Arrest and Apoptosis in Lung Carcinoma Cells

Plasma Chemistry and Plasma Processing - Non-thermal plasma has been a promising new cancer treatment modality in plasma oncology field. It generates extracellular and intracellular reactive...