Thermodynamics of Dyonic NUT Charged Black Holes with entropy as Noether charge

We investigate the thermodynamic behaviour of Lorentzian Dyonic Taub-NUT Black Hole spacetimes. We consider two possibilities in their description: one in which their entropy is interpreted to be one quarter of the horizon area (the horizon entropy), and another in which the Misner string also contributes to the entropy (the Noether charge entropy). We find that there can be as many as three extremal black holes (or as few as zero) depending on the choice of parameters, and that the dependence of the free energy on temperature — and the resultant phase behaviour — depends very much on which of these situations holds. Some of the phase behaviour we observe holds regardless of which interpretation of the entropy holds. However another class of phase transition structures occurs only if the Noether charge interpretation of the entropy is adopted.

Perturbing the O–H…O Hydrogen Bond in 1-oxo-3-hydroxy-2-propene

Ab initio MP2/aug’-cc-pVTZ calculations have been carried out to identify and characterize equilibrium structures and transition structures on the 1-oxo-3-hydroxy-2-propene: Lewis acid potential energy surfaces, with the acids LiH, LiF, BeH2, and BeF2. Two equilibrium structures, one with the acid interacting with the C=O group and the other with the interaction occurring at the O–H group, exist on all surfaces. These structures are separated by transition structures that present the barriers to the interconversion of the two equilibrium structures. The structures with the acid interacting at the C=O group have the greater binding energies. Since the barriers to convert the structures with interaction occurring at the O–H group are small, only the isomers with interaction occurring at the C=O group could be experimentally observed, even at low temperatures. Charge-transfer energies were computed for equilibrium structures, and EOM-CCSD spin–spin coupling constants 2hJ(O–O), 1hJ(H–O), and 1J(O–H) were computed for equilibrium and transition structures. These coupling constants exhibit a second-order dependence on the corresponding distances, with very high correlation coefficients.

Identifying the true origins of selectivity in chiral phosphoric acid catalyzed N-acyl-azetidine desymmetrizations

The origins of selectivity in azetidine desymmetrizations have been determined computationally. Comparison of structures with model and full catalysts provided key details missed by typical analyses of the stereodetermining transition structures.

Welding of pipes in fixed position with internal anti-corrosion protection of joints

The article reviews the weldability of clad steel used for protection of inner surface of oil-and-gas pipelines from corrosion by different welding materials. It is indicated that during welding of the root pass by stainless electrodes in one pass the transition structures appear on the interface of two dissimelar metals. This process leads to the formaion of cracks. To reduce negative impact of the transition structures on the characteristics of welded joints it is recommended to weld the first two passes with strainless electrodes.

Perylene bisimide cyclophanes as receptors for planar transition structures – Catalysis of stereoinversions by shape-complementarity and noncovalent π–π interactions

Perylene bisimide (PBI) cyclophanes have been shown to form ideal hosts for large aromatic molecules, offering rigid cavities and ideal monomer spacing for π–π stacking interactions between host and guest....

A balanced-to-balanced directional coupler based on branch-slotline coupled structure

In this paper, a balanced-to-balanced (BTB) branch-slotline directional coupler (DC) is firstly presented, which can realize an arbitrary power division ratios (PDRs). The coupler is composed by microstrip-to-slotline (MS) transition structures and branch-slotline coupled structures. The single-ended to balanced-ended conversion is simplified and easy to implemented by the MS transition structures, which intrinsically leads to the differential-mode (DM) transmission and common-mode (CM) suppression. Moreover, the different PDRs which are controlled by the widths of branch-slotlines can be achieved. In order to verify the feasibility of the proposed design method, two prototype circuits of the proposed coupler with different PDRs are fabricated and measured. The return loss and the isolation of two designs are all better than 10 dB. Moreover, the CM suppressions are greater than 35 dB. A good agreement between the simulation and measurement results is observed.