Synthesis and structures of O-anthrylmethyl-substituted hexahomotrioxacalix[3]arenes

O-Alkylation of 7,15,23-tri-tert-butyl-25,26,27-trihydroxy-2,3,10,11,18,19-hexahomo-3,11,19-trioxacalix[3]arene (1H₃) with 9-chloromethylanthracene 5 was carried out under different reaction conditions. Variation of the number of anthrylmethyl group introduced at the phenolic rim of hexahomotrioxacalix[3]arene 1H₃ was achieved through selective O-alkylation using stoichiometric amounts of 9-chloromethylanthracene 5 in acetone to afford the mono-O-alkylated product 2H₂An, the di-O-alkylated product 3HAn₂ and the tri-O-alkylated product partial-cone-4An₃, respectively. Interestingly, by using an acetone/benzene (1:1 v/v) mixed solvent system, the cone-4An₃ was successfully synthesized. These results suggest that the solvent can also control the conformation of the O-alkylation products. The possible reaction routes of the cone-4An₃ and partial-cone-4An₃ are also discussed

Quantum anomalous vortex and Majorana zero mode in iron-based superconductor Fe(Te,Se)

In topological insulators doped with magnetic ions, spin-orbit coupling and ferromagnetism give rise to the quantum anomalous Hall effect. Here we show that in s-wave superconductors with strong spin-orbit coupling, magnetic impurity ions can generate topological vortices in the absence of external magnetic fields. Such vortices, dubbed quantum anomalous vortices, support robust Majorana zero-energy modes when superconductivity is induced in the topological surface states. We demonstrate that the zero-energy bound states observed in Fe(Te,Se) superconductors are possible realizations of the Majorana zero modes in quantum anomalous vortices produced by the interstitial magnetic Fe. The quantum anomalous vortex matter not only advances fundamental understandings of topological defect excitations of Cooper pairing, but also provides new and advantageous platforms for manipulating Majorana zero modes in quantum computing.Comment: final version, 8 pages, 3 figures + supplemental materia

Interfacial Phonon Scattering and Transmission Loss in >1 um Thick Silicon-on-insulator Thin Films

Scattering of phonons at boundaries of a crystal (grains, surfaces, or solid/solid interfaces) is characterized by the phonon wavelength, the angle of incidence, and the interface roughness, as historically evaluated using a specularity parameter p formulated by Ziman [J. M. Ziman, Electrons and Phonons (Clarendon Press, Oxford, 1960)]. This parameter was initially defined to determine the probability of a phonon specularly reflecting or diffusely scattering from the rough surface of a material. The validity of Ziman's theory as extended to solid/solid interfaces has not been previously validated. To better understand the interfacial scattering of phonons and to test the validity of Ziman's theory, we precisely measured the in-plane thermal conductivity of a series of Si films in silicon-on-insulator (SOI) wafers by time-domain thermoreflectance (TDTR) for a Si film thickness range of 1 - 10 {\mu}m and a temperature range of 100 - 300 K. The Si/SiO2 interface roughness was determined to be 0.11+/-0.04 nm using transmission electron microscopy (TEM). Furthermore, we compared our in-plane thermal conductivity measurements to theoretical calculations that combine first-principles phonon transport with Ziman's theory. Calculations using Ziman's specularity parameter significantly overestimate values from the TDTR measurements. We attribute this discrepancy to phonon transmission through the solid/solid interface into the substrate, which is not accounted for by Ziman's theory for surfaces. We derive a simple expression for the specularity parameter at solid/amorphous interfaces and achieve good agreement between calculations and measurement values.Comment: 4 figures, submitted to PR

The dependence of tidal stripping efficiency on the satellite and host galaxy morphology

In this paper we study the tidal stripping process for satellite galaxies orbiting around a massive host galaxy, and focus on its dependence on the morphology of both satellite and host galaxy. For this purpose, we use three different morphologies for the satellites: pure disc, pure bulge and a mixture bulge+disc. Two morphologies are used for the host galaxies: bulge+disc and pure bulge. We find that while the spheroidal stellar component experiences a constant power-law like mass removal, the disc is exposed to an exponential mass loss when the tidal radius of the satellite is of the same order of the disc scale length. This dramatic mass loss is able to completely remove the stellar component on time scale of 100 Myears. As a consequence two satellites with the same stellar and dark matter masses, on the same orbit could either retain considerable fraction of their stellar mass after 10 Gyrs or being completely destroyed, depending on their initial stellar morphology. We find that there are two characteristic time scales describing the beginning and the end of the disc removal, whose values are related to the size of the disc. This result can be easily incorporated in semi-analytical models. We also find that the host morphology and the orbital parameters also have an effect on the determining the mass removal, but they are of secondary importance with respect to satellite morphology. We conclude that satellite morphology has a very strong effect on the efficiency of stellar stripping and should be taken into account in modeling galaxy formation and evolution.Comment: 11 pages, 9 figures; accepted for publication in MNRA

A computational study of preferential diffusion and scalar transport in nonpremixed hydrogen-air flame

The nonpremixed hydrogen-air reacting flow is simulated using three-dimensional direct numerical simulation coupled with flamelet generated manifolds based on detailed chemical kinetics. From the comparisons between one computational case taking into account preferential diffusion and another case with unity Lewis number assumption, the instantaneous results show that the flow is more vortical in the absence of preferential diffusion. This indicates that preferential diffusion may smooth the flame under certain circumstances when coupled with the intrinsic hydrodynamic instability. The flame compositional structures are also influenced by preferential diffusion in a significant manner. Further, the statistical information suggests that turbulent scalar flux is affected by preferential diffusion. The phenomenon of counter-gradient diffusion of both the conserved and non-conserved scalars can be detected for the two cases. The gradient model for scalar closure is found to be incapable of accurately predicting the scalar transport in nonpremixed hydrogen flames

A coupled thermal and electrochemical study of lithium-ion battery cooled by paraffin/porous-graphite-matrix composite

Lithium-ion (Li-ion) battery cooling using a phase change material (PCM)/compressed expanded natural graphite (CENG) composite is investigated, for a cylindrical battery cell and for a battery module scale. An electrochemistry model (average model) is coupled to the thermal model, with the addition of a one-dimensional model for the solution and solid diffusion using the nodal network method. The analysis of the temperature distribution of the battery module scale has shown that a two-dimensional model is sufficient to describe the transient temperature rise. In consequence, a two-dimensional cell-centred finite volume code for unstructured meshes is developed with additions of the electrochemistry and phase change. This two-dimensional thermal model is used to investigate a new and usual battery module configurations cooled by PCM/CENG at different discharge rates. The comparison of both configurations with a constant source term and heat generation based on the electrochemistry model showed the superiority of the new design. In this study, comparisons between the predictions from different analytical and computational tools as well as open-source packages were carried out, and close agreements have been observed